In situ fast self-assembled preparation of dandelion-like Cu(OH)2@Cu3(HHTP)2 with core-shell heterostructure arrays for electrochemical sensing of formaldehyde in food samples

Formaldehyde is known to harm the respiratory, nervous, and digestive systems of people. In this paper, a novel dandelion-like electrocatalyst with core-shell heterostructure arrays were fast self-assembled prepared in situ using copper foam (CF) as support substrate and 2,3,6,7,10,11 hexahydroxy-triphenyl (HHTP) as ligand (Cu(OH)2@Cu3(HHTP)2/CF) by a simple two-step hydrothermal reaction. The 1D Cu(OH)2 nanorods "core" and the 2D π-conjugated conducting metal-organic frameworks (Cu3(HHTP)2cMOF) "shell" with remote delocalized electrons give the dandelion-like heterogeneous catalysts excellent electrochemical activity such as a large specific surface area, high conductivity and a fast electron transfer rate. The Cu(OH)2@Cu3(HHTP)2/CF exhibited excellent electrocatalytic performance for formaldehyde under alkaline conditions with a linear range of 0.2 μmol/L - 125 μmol/L and 125 μmol/L - 8 mmol/L, a detection limit as low as 15.9 nmol/L (S/N = 3), as well as good accuracy, consistency, and durability, and it effectively identified FA in food.

The 2.5th generation enzymatic sensors based on the construction of quasi-direct electron transfer type NAD(P)-Dependent dehydrogenases

We introduce a versatile method to convert NAD+ or NADP+ -dependent dehydrogenases into quasi-direct electron transfer (quasi-DET)-type dehydrogenases, by modifying with a mediator on the enzyme surface toward the development of 2.5th generation enzymatic sensors. In this study, we use β-hydroxybutyrate (BHB) dehydrogenase (BHBDh) from Alcaligenes faecalis (AfBHBDh) as a representative NAD+ or NADP+ -dependent dehydrogenase. BHBDhs are important in ketone monitoring, especially for the diagnosis of diabetic ketoacidosis. We modified AfBHBDh with a thiol-reactive phenazine ethosulfate (trPES). We designed, constructed, and modified mutant BHBDhs harboring cysteine residues within 20 Å from the C4 nicotinamide in NAD+/NADH. Mutants Ser65Cys, Thr96Cys, and Lys106Cys showed indistinguishable catalytic activities from the wild-type enzyme, even after trPES modification. These trPES-modified mutants were immobilized on gold disk electrodes via amine coupling with succinimide-groups of dithiobis (succinimidyl hexanoate) self-assembled monolayers for electrochemical measurements. Considering there is a wide range of BHB concentrations, we exploited the linear regression in log scales. The linear range for the sensors with trPES-modified BHBDh mutants Ser65Cys, Thr96Cys, and Lys106Cys were 0.1-4.0 mM in both buffer solution and artificial interstitial fluid (ISF). They have limits of detection of 0.047 mM for Ser65Cys, 0.15 mM for Thr96Cys, and 0.060 mM for Lys106Cys in buffer solution, and 0.12 mM, 0.089 mM, and 0.044 mM in artificial ISF, respectively. These results indicate that redox mediator modification of NAD(P)-dependent dehydrogenases converts them into quasi-DET-type dehydrogenases, thereby enabling their utilization in 2.5th generation enzymatic sensors, which will facilitate the construction of enzymatic sensors suitable for continuous monitoring systems.

Tumour microenvironment-responded Fe-doped carbon dots-sensitized cubic Cu2O for Z-scheme heterojunction-enhanced sono-chemodynamic synergistic tumor therapy

The efficacy of electron-hole separation in a single sonosensitizer and the complexities of the tumor microenvironment (TME) present significant challenges to the effectiveness of sonodynamic therapy (SDT). Designing efficient sonosensitizers to enhance electron-hole separation and alleviate TME resistance is crucial yet challenging. Herein, we introduce a novel Z-scheme heterojunctions (HJs) sonosensitizer using Fe-doped carbon dots (CDs) as auxiliary semiconductors to sensitize cubic Cu2O (Fe-CDs@Cu2O) for the first time. Fe-CDs@Cu2O demonstrated enhanced SDT effects due to improved electron-hole separation. Additionally, the introduction of Fe ions in CDs synergistically enhances Fenton-like reactions with Cu ions in Cu2O, resulting in enhanced chemodynamic therapy (CDT) effects. Moreover, Fe-CDs@Cu2O exhibited rapid glutathione (GSH) depletion, effectively mitigating TME resistance. With high rates of 1O2 and OH generated by Fe-CDs@Cu2O, coupled with strong GSH depletion, single drug injection and ultrasound (US) irradiation effectively eliminate tumors. This innovative heterojunction sonosensitizer offers a promising pathway for clinical anti-tumor treatment.

Development of closed bipolar electrode based L-lactate sensor employing quasi-direct electron transfer type enzyme with cyclic voltammetry

Herein, we present a proof-of-concept of an enzyme sensor combining closed bipolar electrode system with quasi-direct electron transfer (DET) type enzyme. The closed bipolar electrode system was tested using cyclic voltammetry, with L-lactate as a model substrate. L-Lactate was detected through measurement of the change in junction potential across the bipolar electrode. This change in junction potential was caused by reduction of amino reactive phenazine ethosulfate conjugated to Aerococcus vilidans derived engineered L-lactate oxidase (AvLOx) which shows a quasi-DET signal. Using the closed bipolar electrode system allowed simultaneous measuring using cyclic voltammetry and open circuit potential (OCP) and achieved a limit of detection of 400 μM and 76.2 μM lactate respectively. The sensor was then demonstrated to perform with equivalent sensitivity using OCP across varying surface areas. To the best of our knowledge this is the first time a closed bipolar electrode system has been used with an enzyme which is capable of quasi-direct or direct electron transfer. This work can be expanded further to other enzymes capable of directly altering the junction potential of an electrode surface.

Conductive and capacitive network for enriching the exoelectrogens and enhancing the extracellular electron transfer in microbial fuel cells

Although lots of nanomaterials modified anodes have been reported to improve the bacterial attachment and extracellular electron transfer (EET) in microbial fuel cells (MFCs), the lack of a three dimensional (3D) conductive and capacitive network severely limited MFCs performance. In this work, 3D conductive networks derived from mucor mycelia were grown on carbon cloth (CC), and capacitive FeMn phosphides/oxides were further anchored on these 3D networks by electrochemical deposition (denoted as FeMn/CMM@CC) to simultaneously address the above challenges. As a result, the multivalent metal active sites were evenly distributed on 3D conductive network, which favored the enrichment of exoelectrogens, mass transport and EET. Consequently, the as-prepared FeMn/CMM@CC anode displayed accumulated charge of 131.4C/m2, higher than bare CC. Meanwhile, FeMn/CMM@CC anode substantially promoted flavin excretion and the amounts of nano conduits. The abundance of Geobacter was 63 % on bare CC, and greatly increased to 83 % on FeMn/CMM@CC. MFCs equipped by FeMn/CMM@CC anode presented the power density of 3.06 W/m2 and coulombic efficiency (29.9 %), evidently higher than bare CC (1.29 W/m2, 7.3 %), and the daily chemical oxygen demand (COD) removal amount also increased to 92.6 mg/L/d. This work developed a facile method to optimize the abiotic-biotic interface by introducing 3D conductive and capacitive network, which was proved to be a promising strategy to modify macro-porous electrodes.

An electron density clustering based adaptive segmentation method for protein Raman spectrum calculation

Raman spectroscopy is a powerful technique for protein detection, but the calculation of Raman spectrum is a longstanding challenging problem due to the large sizes and complex structures of protein molecules. Dividing proteins into fragments can greatly accelerate the calculation, but this usually introduces large errors originating from ignored interactions between fragments into obtained spectra. In this paper, we proposed a new adaptive segmentation method based on the strength of interactions and molecular shapes and structures, i.e., electron density clustering, to divide proteins. It can reduce errors of obtained Raman spectra by about 20% compared to the uniform segmentation method without a significant increase in computational cost. This method can facilitate the validation and analysis of detected Raman spectra of proteins and promote the application of Raman spectroscopy in biological detection.

Exploring phenazine electron transfer interaction with elements of the respiratory pathways of Pseudomonas putida and Pseudomonas aeruginosa

Pseudomonas aeruginosa phenazines contribute to survival under microaerobic and anaerobic conditions by extracellular electron discharge to regulate cellular redox balances. This electron discharge is also attractive to be used for bioelectrochemical applications. However, elements of the respiratory pathways that interact with phenazines are not well understood. Five terminal oxidases are involved in the aerobic electron transport chain (ETC) of Pseudomonas putida and P. aeruginosa. The latter bacterium also includes four reductases that allow for denitrification. Here, we explored if phenazine-1-carboxylic acid interacts with those elements to enhance anodic electron discharge and drive bacterial growth in oxygen-limited conditions. Bioelectrochemical evaluations of terminal oxidase-deficient mutants of both Pseudomonas strains and P. aeruginosa with stimulated denitrification pathways indicated no direct beneficial interaction of phenazines with ETC elements for extracellular electron discharge. However, the single usage of the Cbb3-2 oxidase increased phenazine production, electron discharge, and cell growth. Assays with purified periplasmic cytochromes NirM and NirS indicated that pyocyanin acts as their electron donor. We conclude that phenazines play an important role in electron transfer to, between, and from terminal oxidases under oxygen-limiting conditions and their modulation might enhance EET. However, the phenazine-anode interaction cannot replace oxygen respiration to deliver energy for biomass formation.

Electrochemical biosensor using direct electron transfer and an antibody-aptamer hybrid sandwich for target detection in complex biological samples

Direct electron transfer (DET) between an electrode and redox labels is feasible in electrochemical biosensors using small aptamer-aptamer sandwiches; however, its application is limited in biosensors that rely on larger antibody-antibody sandwiches. The development of sandwich-type biosensors utilizing DET is challenged by the scarcity of aptamer-aptamer sandwich pairs with high affinity in complex biological samples. Here, we introduce an electrochemical biosensor using an antibody-aptamer hybrid sandwich for detecting thrombin in human serum. The biosensor enables rapid DET through an antibody-aptamer hybrid configuration comprising (i) an antibody capture probe that provides high and specific affinity to the target in human serum, (ii) the target thrombin, and (iii) an aptamer detection probe that facilitates convenient terminal conjugation with long flexible spacer DNA and polylinker peptide containing multiple amine-reactive phenazine ethosulfate (arPES) redox labels, allowing the conjugated labels to easily approach the electrode. Rapid repeated DET using arPES-catalyzed NADH oxidation strongly enhanced the electrochemical signals. Properly sized spacer and polylinker provided low nonspecific adsorption of the aptamer probe conjugated with multiple arPESs and low interference with the binding of the aptamer probe. Methods for immobilizing thiol-terminated antibodies on Au electrodes were compared and optimized. The developed biosensor using the antibody-aptamer hybrid sandwich exhibited high sensitivity and selectivity in detecting thrombin, surpassing the limitations of an aptamer-aptamer sandwich owing to the low affinity of thrombin aptamers in human serum. The calculated detection limit of the biosensor was ∼1.5 pM in buffer and ∼2.7 nM in human serum.

Tuning the optoelectronic properties of selenophene-diketopyrrolopyrrole-based non-fullerene acceptor to obtain efficient organic solar cells through end-capped modification

With the goal of developing a high-performance organic solar cell, nine molecules of A2-D-A1-D-A2 type are originated in the current investigation. The optoelectronic properties of all the proposed compounds are examined by employing the DFT approach and the B3LYP functional with a 6-31G (d, p) basis set. By substituting the terminal moieties of reference molecule with newly proposed acceptor groups, several optoelectronic and photovoltaic characteristics of OSCs have been studied, which are improved to a significant level when compared with reference molecule, i.e., absorption properties, excitation energy, exciton binding energy, band gap, oscillator strength, electrostatic potential, light-harvesting efficiency, transition density matrix, open-circuit voltage, fill factor, density of states and interaction coefficient. All the newly developed molecules (P1-P9) have improved λmax, small band gap, high oscillator strengths, and low excitation energies compared to the reference molecule. Among all the studied compounds, P9 possesses the least binding energy (0.24 eV), P8 has high interaction coefficient (0.70842), P3 has improved electron mobility due to the least electron reorganization energy (λe = 0.009182 eV), and P5 illustrates high light-harvesting efficiency (0.7180). P8 and P9 displayed better Voc results (1.32 eV and 1.33 eV, respectively) and FF (0.9049 and 0.9055, respectively). Likewise, the phenomenon of charge transfer in the PTB7-Th/P1 blend seems to be a marvelous attempt to introduce them in organic photovoltaics. Consequently, the outcomes of these parameters demonstrate that adding new acceptors to reference molecule is substantial for the breakthrough development of organic solar cells (OSCs).

Structure and properties of the acellular porcine cornea irradiated with 60Co-γ and electron beam and its histocompatibility

Acellular porcine cornea (APC) has been used in corneal transplantation and treatment of the corneal diseases. Sterilization is a key step before the application of graft, and irradiation is one of the most commonly used methods. In this paper, APC was prepared by the physical freeze-thawing combined with biological enzymes, and the effects of the electron beam (E-beam) and cobalt 60 (60Co-γ) at the dose of 15 kGy on the physicochemical properties, structure, immunogenicity, and biocompatibility of the APC were investigated. After decellularization, the residual DNA was 20.86 ± 1.02 ng/mg, and the α-Gal clearance rate was more than 99%. Irradiation, especially the 60Co-γ, reduced the cornea's transmittance, elastic modulus, enzymatic hydrolysis rate, swelling ratio, and cross-linking degree. Meanwhile, the diameter and spacing of the collagen fibers increased. In the rat subcutaneous implantation, many inflammatory cells appeared in the unirradiated APC, while the irradiated had good histocompatibility, but the degradation was faster. The lamellar keratoplasty in rabbits indicated that compared to the E-beam, the 60Co-γ damaged the chemical bond of collagen to a larger extent, reduced the content of GAGs, and prolonged the complete epithelization of the grafts. The corneal edema was more serious within 1 month after the surgery. After 2 months, the thickness of the APC with the two irradiation methods tended to be stable, but that in the 60Co-γ group became thinner. The pathological results showed that the collagen structure was looser and the pores were larger, indicating the 60Co-γ had a more extensive effect on the APC than the E-beam at 15 kGy.

Enhanced corrosion of 2205 duplex stainless steel by Acetobacter aceti through synergistic electron transfer and organic acids acceleration

Acetobacter aceti is a microbe that produces corrosive organic acids, causing severe corrosion of industrial equipment. Previous studies have focused on the organic acid corrosion of A. aceti, but neglected the possibility that it has electron transfer corrosion. This study found that electron transfer and organic acids can synergistically promote the corrosion of 2205 duplex stainless steel (DSS). Electrochemical measurement results showed that corrosion of 2205 DSS was more severe in the presence of A. aceti. Surface analysis indicated a thick biofilm formed on the steel surface, with low pH and dissolved oxygen concentrations under the biofilm. Corrosion intensified when A. aceti lacked a carbon source, suggesting that A. aceti can corrode metals by using metallic substrates as electron donors, in addition to its acidic by-products.

Electronic, optical, and thermoelectric characteristics of (Ae)xFBiS2 (Ae=Sr, Ba, and x=1.7) layered materials useful in optical modulator devices

The recent discovery of superconductivity behavior in the mother BiS2-layered compounds has captivated the attention of several physicists. The crystal structure of superconductors with alternate layers of BiS2 is homologous to that of cuprates and Fe-based superconductors. The full-potential linearized augmented plane-wave (FP-LAPW) technique was utilized to investigate the electronic structures and density of states in the vicinity of the Fermi energy of SrFBiS2 and BaFBiS2 compounds under the electron carriers doping. The introduction of electron doping (carries doping) reveals that the host compounds SrFBiS2 and BaFBiS2 exhibit features indicative of superconductivity. This carrier doping of SrFBiS2 and BaFBiS2 compounds (electron-doped) has a significant impact on the lowest conduction states near the Fermi level for the emergence of the superconducting aspect. The electron doping modifies and induces changes in the electronic structures with superconducting behavior in (Ae)1.7FBiS2(Ae=Sr,Ba) compounds. A Fermi surface nesting occurred under the modification of electrons (carriers) doping in the host compounds SrFBiS2 and BaFBiS2. Furthermore, the optical characteristics of the carrier-doped SrFBiS2 and BaFBiS2 compounds are simulated. Due to the anisotropic behavior, the optical properties of these materials based on BiS2 demonstrate a pronounced polarization dependency. The starting point at zero photon energy in the infrared region is elucidated by considering the Drude features in the optical conductivity spectra of SrFBiS2 and BaFBiS2 compounds, when the electron carriers doping is applied. It was clearly noticed that the spin-orbit coupling (SOC) influences the electronic band structures, density of states, Femi surface, and optical features because of the heavy Bismuth atom, which may disclose fascinating aspects. Further, we conducted simulations to assess the thermoelectric properties of these mother compounds. The two BiS2-layered compounds could be suitable for practical thermoelectric purposes and are highlighted through assessment of electrical conductivity, thermal conductivity, Seebeck coefficient, and power factor. As a result, we propose that the mechanisms of superconducting behavior in BiS2 family may pave new avenues for investigating the field of unconventional superconductivity. It may also provide new insights into the origin of high-Tc superconductivity nature.

Constructing extrinsic oxygen vacancy on the surface of photocatalyst as CO2 and electrons reservoirs to improve photocatalytic CO2 reduction activity

Constructing own oxygen vacancies in the photocatalysts is a very promising method to improve their photocatalytic CO2 reduction activity. However, some catalysts have excellent stabilities, making it difficult for them to construct their own oxygen vacancies. To simplify the above difficulty of stable photocatalysts, constructing extrinsic oxygen vacancies on their surface as a novel idea is proposed. Here, a stable TiO2 nanosheet is chosen as a research object, we uniformly deposited BiOCl quantum dots on their surface via a simple adsorption-deposition method. It is found that BiOCl quantum dots are able to simultaneously self-transform into defective BiOCl with many oxygen vacancies when the photocatalyst is performed photocatalytic CO2 reduction. These extrinsic oxygen vacancies can act as "CO2 and photo-generated electrons reservoirs" to improve CO2 capture and accelerate the separation of photogenerated electrons and holes. For the above reasons, the modified TiO2 showed obvious enhancement of photocatalytic CO2 reduction compared to pristine TiO2 and BiOCl. This work may open a new avenue to broaden the use of oxygen vacancies in the process of photocatalytic CO2 reduction.

Structural modification of A-C-A configured X-PCIC acceptor molecule for efficient photovoltaic properties with low energy loss in organic solar cells

Modification of terminal acceptors of non-fullerene organic solar cell molecule with different terminal acceptors can help in screening of molecules to develop organic photovoltaic cells with improved performance. Thus, in this work, seven new molecules with an unfused core have been designed and thoroughly investigated. DFT/TD-DFT simulations were performed on studied molecules to explore the ground and excited state characteristics. UV-Visible analysis revealed the red shift in the absorption spectrum (reaching 781 nm) owing to their smaller energy gap up to 1.94 eV. Furthermore, transition density matrix analysis demonstrated that peripheral acceptors extract the electron density from the core effectively. The effectiveness of our investigated molecules as materials for high-performing organic photovoltaic cells has been shown by an examination of their electron and hole mobilities for fast charge transfer. When combined with PTB7-Th, all molecules displayed high open circuit voltage. XP5 molecule exhibited highest open circuit voltage (1.70 eV) and lowest energy loss of 0.30 eV. All designed molecules exhibit the improved aforementioned parameters, which shows that these molecules can be used to develop competent solar devices in future.

Understanding of the stability of acyclic nitronic acids in the light of molecular electron density theory

In the present work, the electronic structure and stability of acyclic nitronic acids were studied. Depending on the different substituents, the analyzed compounds can be classified as pseudo(mono)radical or zwitterionic nitronic acids. ELF topological analysis of the electron density of nitronic acids containing in their structure EWG substituent (-NO2 (1); -COOCH3 (2); -NO2, -CH3 (5); -COOCH3, -OCH3 (6); -NO2, -H (7); -COOH3, -H (8)) permits establishing a pseudo(mono)radical electronic structure with a pseudoradical centers at the C1 carbon atom. In turn, ELF analysis of the compounds 3, 4, 9 and 10 containing substituent belonging to the EGD group (-CH3 (3); -OCH3 (4); -CH3, -H (9); -COH3, -H (10)) and based on the presence of C1-N2 double bond and absence of pseudoradical centre allows for the classification of these compounds as a zwitterionic nitronic acids. Nitronic acids containing EDG substituents in their structure are the most stable among the analyzed nitronic acids. In turn, nitronic acids containing EWG groups are characterized by higher reactivity in chemical reactions compared to other analyzed nitronic acids.

Concomitant investigation of crustacean amphipods lipidome and metabolome during the molting cycle by Zeno SWATH data-independent acquisition coupled with electron activated dissociation and machine learning

BACKGROUND

DIA (Data-Independent Acquisition) is a powerful technique in Liquid Chromatography coupled with high-resolution tandem Mass Spectrometry (LC-MS/MS) initially developed for proteomics studies and recently emerging in metabolomics and lipidomics. It provides a comprehensive and unbiased coverage of molecules with improved reproducibility and quantitative accuracy compared to Data-Dependent Acquisition (DDA). Combined with the Zeno trap and Electron-Activated Dissociation (EAD), DIA enhances data quality and structural elucidation compared to conventional fragmentation under CID. These tools were applied to study the lipidome and metabolome of the freshwater amphipod Gammarus fossarum, successfully discriminating stages and highlighting significant biological features. Despite being underused, DIA, along with the Zeno trap and EAD, holds great potential for advancing research in the omics field.

RESULTS

DIA combined with the Zeno trap enhances detection reproducibility compared to conventional DDA, improving fragmentation spectra quality and putative identifications. LC coupled with Zeno-SWATH-DIA methods were used to characterize molecular changes in reproductive cycle of female gammarids. Multivariate data analysis including Principal Component Analysis and Partial Least Square Discriminant Analysis successfully identified significant features. EAD fragmentation helped to identify unknown features and to confirm their molecular structure using fragmentation spectra database annotation or machine learning. EAD database matching accurately annotated five glycerophospholipids, including the position of double bonds on fatty acid chain moieties. SIRIUS database predicted structures of unknown features based on experimental fragmentation spectra to compensate for database incompleteness.

SIGNIFICANCE

Reproducible detection of features and confident identification of putative compounds are pivotal stages within analytical pipelines. The DIA approach combined with Zeno pulsing enhances detection sensitivity and targeted fragmentation with EAD in positive polarity provides orthogonal fragmentation information. In our study, Zeno-DIA and EAD thereby facilitated a comprehensive and insightful exploration of pertinent biological molecules associated with the reproductive cycle of gammarids. The developed methodology holds great promises for identifying informative biomarkers on the health status of an environmental sentinel species.

Conductive magnetic nanowires accelerated electron transfer between C1020 carbon steel and Desulfovibrio vulgaris biofilm

Microbial biofilms are behind microbiologically influenced corrosion (MIC). Sessile cells in biofilms are many times more concentrated volumetrically than planktonic cells in the bulk fluids, thus providing locally high concentrations of chemicals. More importantly, "electroactive" sessile cells in biofilms are capable of utilizing extracellularly supplied electrons (e.g., from elemental Fe) for intracellular reduction of an oxidant such as sulfate in energy metabolism. MIC directly caused by anaerobic biofilms is classified into two main types based on their mechanisms: extracellular electron transfer MIC (EET-MIC) and metabolite MIC (M-MIC). Sulfate-reducing bacteria (SRB) are notorious for their corrosivity. They can cause EET-MIC in carbon steel, but they can also secrete biogenic H2S to corrode other metals such as Cu directly via M-MIC. This study investigated the use of conductive magnetic nanowires as electron mediators to accelerate and thus identify EET-MIC of C1020 by Desulfovibrio vulgaris. The presence of 40 ppm (w/w) nanowires in ATCC 1249 culture medium at 37 °C resulted in 45 % higher weight loss and 57 % deeper corrosion pits after 7-day incubation. Electrochemical tests using linear polarization resistance and potentiodynamic polarization supported the weight loss data trend. These findings suggest that conductive magnetic nanowires can be employed to identify EET-MIC. The use of insoluble 2 μm long nanowires proved that the extracellular section of the electron transfer process is a bottleneck in SRB MIC of carbon steel.

Elucidating the impacts of cobalt (II) ions on extracellular electron transfer and pollutant degradation by anodic biofilms in bioelectrochemical systems during industrial wastewater treatment

Electrogenic biofilms in bioelectrochemical systems (BES) are critical in wastewater treatment. Industrial effluents often contain cobalt (Co2+); however, its impact on biofilms is unknown. This study investigated how increasing Co2+ concentrations (0-30 mg/L) affect BES biofilm community dynamics, extracellular polymeric substances, microbial metabolism, electron transfer gene expression, and electrochemical performance. The research revealed that as Co2+ concentrations increased, power generation progressively declined, from 345.43 ± 4.07 mW/m2 at 0 mg/L to 160.51 ± 0.86 mW/m2 at 30 mg/L Co2+. However, 5 mg/L Co2+ had less effect. The Co2+ removal efficiency in the reactors fed with 5 and 10 mg/L concentrations exceeded 99% and 94%, respectively. However, at 20 and 30 mg/L, the removal efficiency decreased substantially, likely because of reduced biofilm viability. FTIR indicated the participation of biofilm functional groups in Co2+ uptake. XPS revealed Co2+ presence in biofilms as CoO and Co(OH)2, indicating precipitation also aided removal. Cyclic voltammetry and electrochemical impedance spectroscopy tests revealed that 5 mg/L Co2+ had little impact on the electrocatalytic activity, while higher concentrations impaired it. Furthermore, at a concentration of 5 mg/L Co2+, there was an increase in the proportion of the genus Anaeromusa-Anaeroarcus, while the genus Geobacter declined at all tested Co2+ concentrations. Additionally, higher concentrations of Co2+ suppressed the expression of extracellular electron transfer genes but increased the expression of Co2+-resistance genes. Overall, this study establishes how Co2+ impacts electrogenic biofilm composition, function, and treatment efficacy, laying the groundwork for the optimized application of BES in remediating Co2+-contaminated wastewater.

Efficient nitrate and Cr(VI) removal by denitrifier: The mechanism of S. oneidensis MR-1 promoting electron production, transportation and consumption

When Cr(VI) and nitrate coexist, the efficiency of both bio-denitrification and Cr(VI) bio-reduction is poor because chromate hinders bacterial normal functions (i.e., electron production, transportation and consumption). Moreover, under anaerobic condition, the method about efficient nitrate and Cr(VI) removal remained unclear. In this paper, the addition of Shewanella oneidensis MR-1 to promote the electron production, transportation and consumption of denitrifier and cause an increase in the removal of nitrate and Cr(VI). The efficiency of nitrate and Cr(VI) removal accomplished by P. denitrificans as a used model denitrifier increased respectively from 51.3% to 96.1% and 34.3% to 99.8% after S. oneidensis MR-1 addition. The mechanism investigations revealed that P. denitrificans provided S. oneidensis MR-1 with lactate, which was utilized to secreted riboflavin and phenazine by S. oneidensis MR-1. The riboflavin served as coenzymes of cellular reductants (i.e., thioredoxin and glutathione) in P. denitrificans, which created favorable intracellular microenvironment conditions for electron generation. Meanwhile, phenazine promoted biofilm formation, which increased the adsorption of Cr(VI) on the cell surface and accelerated the Cr(VI) reduction by membrane bound chromate reductases thereby reducing damage to other enzymes respectively. Overall, this strategy reduced the negative effect of chromate, thus improved the generation, transportation, and consumption of electrons. SYNOPSIS: The presence of S. oneidensis MR-1 facilitated nitrate and Cr(VI) removal by P. denitrificans through decreasing the negative effect of chromate due to the metabolites' secretion.

Fulvic acid more facilitated the soil electron transfer than humic acid

Humus substances (HSs) participate in extracellular electron transfer (EET), which is unclear in heterogeneous soil. Here, a microbial electrochemical system (MES) was constructed to determine the effect of HSs, including humic acid, humin and fulvic acid, on soil electron transfer. The results showed that fulvic acid led to the optimal electron transfer efficiency in soil, as evidenced by the highest accumulated charges and removal of total petroleum hydrocarbons after 140 days, with increases of 161% and 30%, respectively, compared with those of the control. However, the performance of MES with the addition of humic acid and humin was comparable to that of the control. Fulvic acid amendment enhanced the carboxyl content and oxidative state of dissolved organic matter, endowing a better electron transfer capacity. Additionally, the presence of fulvic acid induced an increase in the abundance of electroactive bacteria and organic degraders, extracellular polymeric substances and functional enzymes such as cytochrome c and NADH synthesis, and the expression of m tr C gene, which is responsible for EET enhancement in soil. Overall, this study reveals the mechanism by which HSs stimulate soil electron transfer at the physicochemical and biological levels and provides basic support for the application of bioelectrochemical technology in soil.

Unlocking the power of activated carbon-mediated peracetic acid activation for efficient antibiotics abatement in groundwater: Coupling the processes of electron transfer, radical production, and adsorption

The activation of peracetic acid (PAA) by activated carbon (AC) is a promising approach for reducing micropollutants in groundwater. However, to harness the PAA/AC system's potential and achieve sustainable and low-impact groundwater remediation, it is crucial to quantify the individual contributions of active species. In this study, we developed a combined degradation kinetic and adsorption mass transfer model to elucidate the roles of free radicals, electron transfer processes (ETP), and adsorption on the degradation of antibiotics by PAA in groundwater. Our findings reveal that ETP predominantly facilitated the activation of PAA by modified activated carbon (AC600), contributing to ∼61% of the overall degradation of sulfamethoxazole (SMX). The carbonyl group (CO) on the surface of AC600 was identified as a probable site for the ETP. Free radicals contributed to ∼39% of the degradation, while adsorption was negligible. Thermodynamic and activation energy analyses indicate that the degradation of SMX within the PAA/AC600 system requires a relatively low energy input (27.66 kJ/mol), which is within the lower range of various heterogeneous Fenton-like reactions, thus making it easily achievable. These novel insights enhance our understanding of the AC600-mediated PAA activation mechanism and lay the groundwork for developing efficient and sustainable technologies for mitigating groundwater pollution. ENVIRONMENTAL IMPLICATION: The antibiotics in groundwater raises alarming environmental concerns. As groundwater serves as a primary source of drinking water for nearly half the global population, the development of eco-friendly technologies for antibiotic-contaminated groundwater remediation becomes imperative. The innovative PAA/AC600 system demonstrates significant efficacy in degrading micropollutants, particularly sulfonamide antibiotics. By integrating degradation kinetics and adsorption mass transfer models, this study sheds light on the intricate mechanisms involved, emphasizing the potential of carbon materials as sustainable tools in the ongoing battle for clean and safe groundwater.

Fenton-like membrane reactor assembled by electron polarization and defect engineering modifying Co3O4 spinel for flow-through removal of organic contaminants

The application of Fenton-like membrane reactors for water purification offers a promising solution to overcome technical challenges associated with catalyst recovery, reaction efficiency, and mass transfer typically encountered in heterogeneous batch reaction modes. This study presents a dual-modification strategy encompassing electron polarization and defect engineering to synthesize Al-doped and oxygen vacancies (OV)-enriched Co3O4 spinel catalysts (ACO-OV). This modification empowered ACO-OV with exceptional performance in activating peroxymonosulfate (PMS) for the removal of organic contaminants. Moreover, the ACO-OV@polyethersulfone (PES) membrane/PMS system achieved organic contaminant removal through filtration (with a reaction kinetic constant of 0.085 ms-1), demonstrating outstanding resistance to environmental interference and high operational stability. Mechanistic investigations revealed that the exceptional catalytic performance of this Fenton-like membrane reactor stemmed from the enrichment of reactants, exposure of reactive sites, and enhanced mass transfer within the confined space, leading to a higher availability of reactive species. Theoretical calculations were conducted to validate the beneficial intrinsic effects of electron polarization, defect engineering, and the confined space within the membrane reactor on PMS activation and organic contaminant removal. Notably, the ACO-OV@PES membrane/PMS system not only mineralized the targeted organic contaminants but also effectively mitigated their potential environmental risks. Overall, this work underscores the significant potential of the dual-modification strategy in designing spinel catalysts and Fenton-like membrane reactors for efficient organic contaminant removal.

Low-interference and sensitive electrochemical detection of glucose and lactate using boron-doped diamond electrode and electron mediator menadione

To minimize background interference in electrochemical enzymatic biosensors employing electron mediators, it is essential for the electrochemical oxidation of electroactive interfering species (ISs), such as ascorbic acid (AA), to proceed slowly, and for the redox reactions between electron mediators and ISs to occur at a low rate. In this study, we introduce a novel combination of a working electrode and an electron mediator that effectively mitigates interference effects. Compared to commonly used electrodes such as Au, glassy carbon, and indium tin oxide (ITO), boron-doped diamond (BDD) electrodes demonstrate significantly lower anodic current (i.e., lower background levels) in the presence of AA. Additionally, menadione (MD) exhibits notably slower reactivity with AA compared to other electron mediators such as Ru(NH3)63+, 4-amino-1-naphthol, and 1,4-naphthoquinone, primarily due to the lower formal potential of MD compared to AA. This synergistic combination of BDD electrode and MD is effectively applied in three biosensors: (i) glucose detection using electrochemical-enzymatic (EN) redox cycling, (ii) glucose detection using electrochemical-enzymatic-enzymatic (ENN) redox cycling, and (iii) lactate detection using ENN redox cycling. Our developed approach significantly outperforms the combination of ITO electrode and MD in minimizing IS interference. Glucose in artificial serum can be detected with detection limits of ~ 20 μM and ~ 3 μM in EN and ENN redox cycling, respectively. Furthermore, lactate in human serum can be detected with a detection limit of ~ 30 μM. This study demonstrates sensitive glucose and lactate detection with minimal interference, eliminating the need for (bio)chemical agents to remove interfering species.

Improving Calculations of Electron Eye-lens Operational Dose Coefficients Using the Monte Carlo Codes PENELOPE and MCNP6.2

ABSTRACT

After considering epidemiological studies on the induction of cataracts in individuals exposed to radiation, the International Commission on Radiological Protection recommended, in 2012, a reduction in the annual eye-dose limit of occupationally exposed workers. This imposed higher performance demands on existing dosimetry systems and the development of new dosimetry technologies. The operational quantity to be measured is Hp(3), the personal dose equivalent at a depth of 3 mm in an ICRU 4-element tissue cylinder 20 cm in height and 20 cm in diameter. The conversion coefficients per unit incident fluence, Hp(3)/Φ, were calculated using Monte Carlo simulation codes. In the case of incident electrons, the literature shows that the resulting coefficients depend on the electron transport options selected for the Monte Carlo simulations as well as the tally zone thickness. In this study, electron operational eye-lens dose coefficients were calculated using MCNP6.2 in its default settings and by invoking the single-event feature. The results were compared to those from PENELOPE, a well-known code for its enhanced accuracy in handling low-energy electron transport. The results are in agreement for the entire energy range for these two series of simulations, but differences are found with previously published dose coefficients in the literature. This impacts the calibration of dosimeters for electrons and may require a change in the commonly accepted dose coefficients.

Fe2+-NTA synergized UV254 photolytic defluorination of perfluorooctane sulfonate (PFOS): Enhancing through intramolecular electron density perturbation via electron acquisition

Perfluorooctane sulfonate (PFOS) is a persistent organic pollutant posing a risk in environmental persistence, bioaccumulation and biotoxicity. This study was to reach a comprehensive and deeper understanding of PFOS elimination in a UV254 photolytic treatment with the co-presence of Fe2+ and nitrilotriacetic acid trisodium salt (NTA). PFOS defluorination was noticeably enhanced in the UV/Fe2+-NTA treatment compared with UV/NTA, UV/Fe2+ and our previously studied UV/Fe3+ treatments. UV-vis, FTIR, and UPLC/MS-MS results indicated the formation of PFOS-Fe2+-NTA complex in PFOS, Fe2+ and NTA mixture. The transition energy gap of PFOS-Fe2+-NTA decreased below the excitation energy supplied by UV254 irradiation, corresponding with red shift appearing in UV-vis scanning spectrum. This favored intramolecular electron transfer from Fe2+-NTA to PFOS under UV254 irradiation to form electron-accepting PFOS. Molecular electrostatic potential and atom charge distribution analyses suggested electron density rearrangement and perturbation in the perfluorinated carbon chain of electron-accepting PFOS, leading to the decrease in bond dissociation energies. Intermediate products detection suggested the parallel defluorination pathways of PFOS desulfonation, middle carbon chain scission and direct C-F cleavage. NTA exhibited crucial functions in the UV/Fe2+-NTA treatment by holding Fe2+/Fe3+ in soluble form as a chelant and favoring water activation to generate hydrated electrons (eaq-) under UV irradiation as a photosensitizer. Fe2+ acting as the conduit for electron transfer and the bridge of PFOS anion and NTA was thought functioning best at 200 µM in this study. The degree of UV/Fe2+-NTA -synergized PFOS defluorination also depended on eaq- yield and UV254 photon flux. The structure dependence on the electron transfer process of PFOS and PFOA was explored incorporating molecular structure descriptors. Because of possessing greater potential to acquire electrons or less likeliness to donate its electrons than PFOA, PFOS exhibited faster defluorination kinetics in the published "reduction treatments" than "oxidation" ones. Whereas, PFOA defluorination kinetics were at similar level in both "reduction" and "oxidation" treatments.

Fine molecular structure and digestibility changes of potato starch irradiated with electron beam and X-ray

The change of digestibility of starch irradiated with different types from the perspective of fine structure is not well understood. In this work, the change of internal structure, molecular weight and chain-length distribution, helical structure, lamellar structure, fractal structure and digestibility of native and treated potato starch with electron beam and X-ray was analyzed. Two irradiations caused the destruction of internal structure, the disappearance of growth rings and increase of pores. Irradiation degraded starch to produce short chains and to decrease molecular weight. Irradiation increased double helical content and the thickness and peak area of lamellar structure, resulting in the reorganization of amylopectin and increase of structure order degree. The protected glycosidic linkages increased starch resistance to hydrolase attack, thereby enhancing the anti-digestibility of irradiated starch. Pearson correlation matrix also verified the above-mentioned results. Moreover, X-ray more increased the anti-digestibility of starch by enhancing ability to change fine structure.

Application of electron beam technology to decompose per- and polyfluoroalkyl substances in water

The widespread detection of per- and polyfluoroalkyl substances (PFAS) in environmental compartments across the globe has raised several health concerns. Destructive technologies that aim to transform these recalcitrant PFAS into less toxic, more manageable products, are gaining impetus to address this problem. In this study, a 9 MeV electron beam accelerator was utilized to treat a suite of PFAS (perfluoroalkyl carboxylates: PFCAs, perfluoroalkyl sulfonates, and 6:2 fluorotelomer sulfonate: FTS) at environmentally relevant levels in water under different operating and water quality conditions. Although perfluorooctanoic acid and perfluorooctane sulfonic acid showed >90% degradation at <500 kGy dose at optimized conditions, a fluoride mass balance revealed that complete defluorination occurred only at/or near 1000 kGy. Non-target and suspect screening revealed additional degradation pathways differing from previously reported mechanisms. Treatment of PFAS mixtures in deionized water and groundwater matrices showed that FTS was preferentially degraded (∼90%), followed by partial degradation of long-chain PFAS (∼15-60%) and a simultaneous increase of short-chain PFAS (up to 20%) with increasing doses. The increase was much higher (up to 3.5X) in groundwaters compared to deionized water due to the presence of PFAS precursors as confirmed by total oxidizable precursor (TOP) assay. TOP assay of e-beam treated samples did not show any increase in PFCAs, confirming that e-beam was effective in also degrading precursors. This study provides an improved understanding of the mechanism of PFAS degradation and revealed that short-chain PFAS are more resistant to defluorination and their levels and regulation in the environment will determine the operating conditions of e-beam and other PFAS treatment technologies.

Light and electron microscopic observations on retinal neurons of red-tail shark (Epalzeorhynchos bicolor H. M. Smith, 1931)

The structure of photoreceptors (PR) and the arrangement of neurons in the retina of red-tail shark were investigated using light and electron microscopy. The PR showed a mosaic arrangement and included double cones, single cones (SC), and single rods. Most cones occur as SC. The ratio between the number of cones and rods was 3:1.39 (±0.29). The rods were tall that reached the pigmented epithelium. The outer plexiform layer (OPL) showed a complex synaptic connection between the horizontal and photoreceptor terminals that were surrounded by Müller cell processes. Electron microscopy showed that the OPL possessed both cone pedicles and rod spherules. Each rod spherule consisted of a single synaptic ribbon within the invaginating terminal endings of the horizontal cell (hc) processes. In contrast, the cone pedicles possessed many synaptic ribbons within their junctional complexes. The inner nuclear layer consisted of bipolar, amacrine, Müller cells, and hc. Müller cells possessed intermediate filaments and cell processes that can reach the outer limiting membrane and form connections with each other by desmosomes. The ganglion cells were large multipolar cells with a spherical nucleus and Nissl' bodies in their cytoplasm. The presence of different types of cones arranged in a mosaic pattern in the retina of this species favors the spatial resolution of visual objects. RESEARCH HIGHLIGHTS: This is the first study demonstrating the structure and arrangement of retinal neurons of red-tail shark using light and electron microscopy. The current study showed the presence of different types of cones arranged in a mosaic pattern that may favor the spatial resolution of visual objects in this species. The bipolar, amacrine, Müller, and horizontal cells could be demonstrated.

Noncontrast Myocardial Characterization in Acute Myocardial Infarction Using Electron Density Imaging

PURPOSE

Spectral computed tomography (CT) enables improved tissue characterization, although virtually all research has focused on contrast-enhanced examinations. We hypothesized that changes in myocardial tissue related to acute myocardial infarction (AMI) might potentially be identified without the need for contrast administration using electron density (ED) imaging.

PATIENTS AND METHODS

This retrospective observational study involved a small series (n = 15) of patients admitted to our institution with a first AMI without signs of hemodynamic instability and identification of a culprit vessel with invasive coronary angiography during the same admission, who also underwent a noncontrast, low-dose chest CT using a dual-layer spectral CT scanner. Images were assessed in search of dark areas with low density on ED imaging, and the mean percentage ED relative to water (%EDW) was calculated.

RESULTS

Using a qualitative approach, ED assessment enabled the identification of 11/15 (73%) affected coronary territories, with a sensitivity of 73% (95% CI: 45; 92%) and a specificity of 87% (95% CI: 69; 96%). AMI segments showed significantly lower ED values than the remote myocardium (103.8 ± 0.8 vs 104.3 ± 0.6 %EDW, P < 0.0001), and a threshold below 103.9 %EDW had a sensitivity of 66% and specificity of 79% for the identification of AMI. In a control group of patients without a history of cardiovascular disease, none had areas with focal reduction of ED following the shape of the myocardial wall.

CONCLUSIONS

In our preliminary series, ED imaging showed the potential to enable the identification of myocardial tissue changes related to AMI without iodinated contrast requirement.

Scanning electron microscopic exploration of intricate pollen morphology and antimicrobial potentials of gourd family

This study employs scanning electron microscopy (SEM) to delve into the intricate pollen morphology of Cucurbitaceae (Gourd Family) species, unraveling the nuanced details of their structural features. Concurrently, the research investigates the antimicrobial potentials encoded within these pollen grains, shedding light on their possible applications in the realm of natural antimicrobial agents. Cucurbitaceae plants showcases significant antibacterial and antifungal potentials, underscoring its potential as a source for novel antimicrobial compounds. This research endeavors to provide a comprehensive analysis of pollen morphometry in 12 Cucurbitaceous species, with the primary goal of identifying pollen morpho-types to enrich the taxonomic understanding of the Cucurbitaceae. Following the Erdtman protocol, the study involved processing, measuring, and capturing pollen grains using SEM techniques. Qualitative data were analyzed to evaluate the variations in pollen types, size, and exine stratified sculptured layering. The pollen grains exhibit characteristics of being monads, ranging in size from medium to very large, with the prevailing shape being prolate-spheroidal in six species. Notably, the maximum polar axis diameter was recorded for Cucurbita pepo (106.3 μm), while the minimum was observed in Zehneria anomala (32.6 μm). The grains of Cucurbitaceae exhibit diverse surface patterns, including reticulate columellae, reticulate, verrucate-scabrate, verrucate-gemmate, echinate baculate, reticulate-perforate, and micro-reticulate. This SEM investigation illuminates the intricacies of Cucurbitaceae pollen morphology while concurrently highlighting their noteworthy antimicrobial potentials. HIGHLIGHTS: High-resolution imaging reveals complex pollen morphology. Identification of unique antimicrobial structures on Cucurbitaceae pollen (gourd family). Exploring medicinal potential: Antimicrobial properties of cucurbitaceae species.

Proposed mechanisms of electron uptake in metal-corroding methanogens and their potential for CO2 bioconversion applications

Some methanogens are electrotrophic bio-corroding microbes that can acquire electrons from solid surfaces including metals. In the laboratory, pure cultures of methanogenic cells oxidize iron-based materials including carbon steel, stainless steel, and Fe0. For buried or immersed pipelines or other metallic structures, methanogens are often major components of corroding biofilms with complex interspecies relationships. Models explaining how these microbes acquire electrons from solid donors are multifaceted and include electron transfer via redox mediators such as H2 or by direct contact through membrane proteins. Understanding the electron uptake (EU) routes employed by corroding methanogens is essential to develop efficient strategies for corrosion prevention. It is also beneficial for the development of bioenergy applications relying on methanogenic EU from solid donors such as bioelectromethanogenesis, hybrid photosynthesis, and the acceleration of anaerobic digestion with electroconductive particles. Many methanogenic species carrying out biocorrosion are the same ones forming the extensive abiotic-biological interfaces at the core of these bio-applications. This review will discuss the interactions between corrosive methanogens and metals and how the EU capability of these microbes can be harnessed for different sustainable biotechnologies.

Characterization of ferredoxins involved in electron transfer pathways for nitrogen fixation implicates differences in electronic structure in tuning 2[4Fe4S] Fd activity

Ferredoxins (Fds) are small proteins which shuttle electrons to pathways like biological nitrogen fixation. Physical properties tune the reactivity of Fds with different pathways, but knowledge on how these properties can be manipulated to engineer new electron transfer pathways is lacking. Recently, we showed that an evolved strain of Rhodopseudomonas palustris uses a new electron transfer pathway for nitrogen fixation. This pathway involves a variant of the primary Fd of nitrogen fixation in R. palustris, Fer1, in which threonine at position 11 is substituted for isoleucine (Fer1T11I). To understand why this substitution in Fer1 enables more efficient electron transfer, we used in vivo and in vitro methods to characterize Fer1 and Fer1T11I. Electrochemical characterization revealed both Fer1 and Fer1T11I have similar redox transitions (-480 mV and - 550 mV), indicating the reduction potential was unaffected despite the proximity of T11 to an iron‑sulfur (FeS) cluster of Fer1. Additionally, disruption of hydrogen bonding around an FeS cluster in Fer1 by substituting threonine with alanine (T11A) or valine (T11V) did not increase nitrogenase activity, indicating that disruption of hydrogen bonding does not explain the difference in activity observed for Fer1T11I. Electron paramagnetic resonance spectroscopy studies revealed key differences in the electronic structure of Fer1 and Fer1T11I, which indicate changes to the high spin states and/or spin-spin coupling between the FeS clusters of Fer1. Our data implicates these electronic structure differences in facilitating electron flow and sets a foundation for further investigations to understand the connection between these properties and intermolecular electron transfer.

Identification of fourth-instar larvae of Aedes albopictus (Skuse) (Diptera: Culicidae) employing scanning electron microscopic tool

Aedes albopictus is a vector of numerous viruses in tropical and subtropical regions worldwide, including encephalitis and dengue fever. Although the identification keys depend exclusively on the characteristics of the fourth larval instar, the studies were carried out using scanning electron microscopy (SEM) on the morphology of Ae. albopictus are still insufficient, and more research is required. Therefore, the purpose of this study was to present a comprehensive description of Ae. albopictus mosquitoes based on the morphological features of their fourth-instar larvae to distinguish them from other mosquito species. Antennae, feeding mouth brushes, mandibles, maxillae, labia, comb scales, anal papillae, siphon, respiratory spiracles, and pecten teeth were among the morphological features specifically described using SEM. The sensilla trichoidea and the sensilla basiconica are the sensory spicules found on the antennal integument. The labrum is a tessellated membrane with two movable brushes on the sides and one middle brush. The mandibles have four sellar setae on the anterolateral side, and the maxillae, which have a thumb-like structure and a palp located laterally and about four-fifths of the way from the maxillary brush base to the maxillary notch, are the articulating appendages. On the apex of the palp, there are five sensilla. The eighth abdominal segment is a tiny pentagonal structure with 12 comb scales laterally and a respiratory siphon dorsally. The siphon has two rows of pectin teeth, with 12 teeth per row. Four pairs of siphonal tufts and five perispiracular lobes surround the respiratory spiracles. The anal segment has four anal papillae, a ventral brush, a dorsal brush, and an incomplete saddle. The findings demonstrate that the fourth-instar larvae of Ae. albopictus have distinctive morphological features, which are crucial for understanding their key characteristics and identifying them, preventing inaccurate identification, and facilitating the control of diseases transmitted by the mosquito vector. RESEARCH HIGHLIGHTS: A detailed description of various taxonomical interest structures for the fourth-instar larvae of Aedes albopictus is included in this study. Scanning electron microscopy is considered a helpful technique for identifying Ae. albopictus larvae in their fourth instar.

Progress and Perspective in harnessing MXene-carbon-based composites (0-3D): Synthesis, performance, and applications

MXene is recognized as a promising catalyst for versatile applications due to its abundant metal sites, physicochemical properties, and structural formation. This comprehensive review offers an in-depth analysis of the incorporation of carbon into MXene, resulting in the formation of MXene-carbon-based composites (MCCs). Pristine MXene exhibits numerous outstanding characteristics, such as its atomically thin 2D structure, hydrophilic surface nature, metallic electrical conductivity, and substantial specific surface area. The introduction of carbon guides the assembly of MCCs through electrostatic self-assembly, pairing positively charged carbon with negatively charged MXene. These interactions result in increased interlayer spacing, reduced ion/electron transport distances, and enhanced surface hydrophilicity. Subsequent sections delve into the synthesis methods for MCCs, focusing on MXene integrated with various carbon structures, including 0D, 1D, 2D, and 3D carbon. Comprehensive discussions explore the distinctive properties of MCCs and the unique advantages they offer in each application domain, emphasizing the contributions and advancements they bring to specific fields. Furthermore, this comprehensive review addresses the challenges encountered by MCCs across different applications. Through these analyses, the review promotes a deeper understanding of exceptional characteristics and potential applications of MCCs. Insights derived from this review can serve as guidance for future research and development efforts, promoting the widespread utilization of MCCs across a broad spectrum of disciplines and spurring future innovations.

NO3- as an electron acceptor elevates antibiotic resistance gene and human bacterial pathogen risks in managed aquifer recharge (MAR): A comparison with O2

Managed aquifer recharge (MAR) stands out as a promising strategy for ensuring water resource sustainability. This study delves into the comparative impact of nitrate (NO3-) and oxygen (O2) as electron acceptors in MAR on water quality and safety. Notably, NO3-, acting as an electron acceptor, has the potential to enrich denitrifying bacteria, serving as hosts for antibiotic resistance genes (ARGs) and enriching human bacterial pathogens (HBPs) compared to O2. However, a direct comparison between NO3- and O2 remains unexplored. This study assessed risks in MAR effluent induced by NO3- and O2, alongside the presence of the typical refractory antibiotic sulfamethoxazole. Key findings reveal that NO3- as an electron acceptor resulted in a 2 times reduction in dissolved organic carbon content compared to O2, primarily due to a decrease in soluble microbial product production. Furthermore, NO3- significantly enriched denitrifying bacteria, the primary hosts of major ARGs, by 747%, resulting in a 66% increase in the overall abundance of ARGs in the effluent of NO3- MAR compared to O2. This escalation was predominantly attributed to horizontal gene transfer mechanisms, as evidenced by a notable 78% increase in the relative abundance of mobile ARGs, alongside a minor 27% rise in chromosomal ARGs. Additionally, the numerous denitrifying bacteria enriched under NO3- influence also belong to the HBP category, resulting in a significant 114% increase in the abundance of all HBPs. The co-occurrence of ARGs and HBPs was also observed to intensify under NO3- influence. Thus, NO3- as an electron acceptor in MAR elevates ARG and HBP risks compared to O2, potentially compromising groundwater quality and safety.

Jianpi-Yangxue-Jiedu decoction improves the energy metabolism of psoriasis mice by regulating the electron transfer of oxidative phosphorylation

ETHNOPHARMACOLOGICAL RELEVANCE

The inflammatory skin condition psoriasis is immune-related. The decoction of Jianpi-Yangxue-Jiiedu (JPYX) is a useful medication for psoriasis. However, the underlying mechanics of JPYX have not yet been clarified.

AIM OF THE STUDY

The objective of this study was to investigate the mechanism underlying the efficacy of JPYX in the treatment of psoriasis in the context of a high-fat diet.

MATERIALS AND METHODS

This work generated a high-fat feeding model of imiquimod (IMQ)-induced psoriasis-like lesion mice. The blood composition of JPYX was examined using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The mechanism of JPYX decoction for treating psoriasis was predicted using methods of network pharmacology, metabolomics, and transcriptomics.

RESULTS

JPYX prevented the release of inflammatory cytokines, decreased keratinocyte proliferation, enhanced the percentage of Treg cells in the skin, lymph nodes, and thymus, and greatly alleviated psoriatic lesions. Network pharmacology predicted that IL-1β, TNF, STAT3, and EGFR may be potential targets, and KEGG results showed that PI3K-AKT-mTOR may be a potential mechanism of action. Verification of experimental data demonstrated that the JPYX decoction dramatically decreased mTOR and AKT phosphorylation. According to metabolomics analysis, amino acids and their metabolites, benzene and its substitutes, aldehyde ketone esters, heterocyclic compounds, etc. were the primary metabolites regulated by JPYX. KEGG enrichment analysis of differential metabolites was performed. Fatty acid biosynthesis, Type I polyketide structures, Steroid hormone biosynthesis, Biosynthesis of unsaturated fatty acid, etc. Transcriptomic results showed that JPYX significantly regulated skin development, keratinocyte differentiation, and oxidative phosphorylation. Further experimental data verification showed that JPYX decoction significantly reduced the mRNA levels of mt-Nd4, mt-Nd5, mt-Nd1, Ifi205, Ifi211, and mt-Atp8.

CONCLUSIONS

JPYX may improve psoriasis by regulating the metabolic pathways of fatty acids and electron transport of oxidative phosphorylation.

External Electrons Directly Stimulate Escherichia coli for Enhancing Biological Hydrogen Production

External electric field has the potential to influence metabolic processes such as biological hydrogen production in microorganisms. Based on this concept, we designed and constructed an electroactive hybrid system for microbial biohydrogen production under an electric field comprised of polydopamine (PDA)-modified Escherichia coli (E. coli) and Ni foam (NF). In this system, electrons generated from NF directly migrate into E. coli cells to promote highly efficient biocatalytic hydrogen production. Compared to that generated in the absence of electric field stimulation, biohydrogen production by the PDA-modified E. coli-based system is significantly enhanced. This investigation has demonstrated the mechanism for electron transfer in a biohybrid system and gives insight into precise basis for the enhancement of hydrogen production by using the multifield coupling technology.

miRNA and DNA analysis by negative ion electron transfer dissociation and infrared multiple-photon dissociation mass spectrometry

BACKGROUND

The use of simple and hybrid fragmentation techniques for the identification of molecules in tandem mass spectrometry provides different and complementary information on the structure of molecules. Nevertheless, these techniques have not been as widely explored for oligonucleotides as for peptides or proteins. The analysis of microRNAs (miRNAs) warrants special attention, given their regulatory role and their relationship with several diseases. The application of different fragmentation techniques will be very interesting for their identification.

RESULTS

Four synthetic miRNAs and a DNA sequence were fragmented in an ESI-FT-ICR mass spectrometer using both simple and hybrid fragmentation techniques: CID, nETD followed by CID, IRMPD, and, for the first time, nETD in combination with IRMPD. The main fragmentation channel was base loss. The use of nETD-IRMPD resulted in d/z, a/w, and c/y ions at higher intensities. Moreover, nETD-IRMPD provided high sequence coverage and low internal fragmentation. Native MS analysis revealed that only miR159 and the DNA sequence formed stable dimers under physiological ionic strength. The use of organic co-solvents or additives resulted in a lower sequence coverage due to lesser overall ionization efficiency.

NOVELTY

This work demonstrates that the combination of nETD and IRMPD for miRNA fragmentation constitutes a suitable alternative to common fragmentation methods. This strategy resulted in efficient fragmentation of [miRNA]5- using low irradiation times and fewer internal fragments while ensuring a high sequence coverage. Moreover, given that such low charge states predominate upon spraying in physiological-like conditions, native MS can be applied for obtaining structural information at the same time.

Autobench V1.0: Benchmarking Automation for Electronic Structure Calculations

This work reports on new software for automatic conformer energy benchmarking calculations for flexible molecules. The software workflow consists of four parts: conformational search, preoptimization, optimization, and frequency calculations at a higher level and last calculations using several theoretical levels. The software was written to be user-friendly and versatile to be used by nonexperts in computational chemistry. Any theoretical levels available in either Gaussian 16 or ORCA 5 may be applied in the benchmarking study. The workflow will automatically run conformational search calculations and deal with conformers that converge to the same minimum and those that show a negative frequency. At the end of the workflow, the user will have the mean absolute deviations and the most accurate method/DFT functional and basis set in comparison to the benchmark to be applied for the molecular system of interest. Case examples are given at the end of the paper that may help users to get insight into the software's main features.

Nonbonded Force Field Parameters from MBIS Partitioning of the Molecular Electron Density Improve Binding Affinity Predictions of the T4-Lysozyme Double Mutant

The use of computer simulation for binding affinity prediction is growing in drug discovery. However, its wider use is constrained by the accuracy of the free energy calculations. The key sources of error are the force fields used to depict molecular interactions and insufficient sampling of the configurational space. To improve the quality of the force field, we developed a Python-based computational workflow. The workflow described here uses the minimal basis iterative stockholder (MBIS) method to determine atomic charges and Lennard-Jones parameters from the polarized molecular density. This is done by performing electronic structure calculations on various configurations of the ligand when it is both bound and unbound. In addition, we validated a simulation procedure that accounts for the protein and ligand degrees of freedom to precisely calculate binding free energies. This was achieved by comparing the self-adjusted mixture sampling and nonequilibrium thermodynamic integration methods using various protein and ligand conformations. The accuracy of predicting binding affinity is improved by using MBIS-derived force field parameters and a validated simulation procedure. This improvement surpasses the chemical precision for the eight aromatic ligands, reaching a root-mean-square error of 0.7 kcal/mol.

State-of-the-art silicon carbide diode dosimeters for ultra-high dose-per-pulse radiation at FLASH radiotherapy

Objective.The successful implementation of FLASH radiotherapy in clinical settings, with typical dose rates >40 Gy s-1, requires accurate real-time dosimetry.Approach.Silicon carbide (SiC) p-n diode dosimeters designed for the stringent requirements of FLASH radiotherapy have been fabricated and characterized in an ultra-high pulse dose rate electron beam. The circular SiC PiN diodes were fabricated at IMB-CNM (CSIC) in 3μm epitaxial 4H-SiC. Their characterization was performed in PTB's ultra-high pulse dose rate reference electron beam. The SiC diode was operated without external bias voltage. The linearity of the diode response was investigated up to doses per pulse (DPP) of 11 Gy and pulse durations ranging from 3 to 0.5μs. Percentage depth dose measurements were performed in ultra-high dose per pulse conditions. The effect of the total accumulated dose of 20 MeV electrons in the SiC diode sensitivity was evaluated. The temperature dependence of the response of the SiC diode was measured in the range 19 °C-38 °C. The temporal response of the diode was compared to the time-resolved beam current during each electron beam pulse. A diamond prototype detector (flashDiamond) and Alanine measurements were used for reference dosimetry.Main results.The SiC diode response was independent both of DPP and of pulse dose rate up to at least 11 Gy per pulse and 4 MGy s-1, respectively, with tolerable deviation for relative dosimetry (<3%). When measuring the percentage depth dose under ultra-high dose rate conditions, the SiC diode performed comparably well to the reference flashDiamond. The sensitivity reduction after 100 kGy accumulated dose was <2%. The SiC diode was able to follow the temporal structure of the 20 MeV electron beam even for irregular pulse estructures. The measured temperature coefficient was (-0.079 ± 0.005)%/°C.Significance.The results of this study demonstrate for the first time the suitability of silicon carbide diodes for relative dosimetry in ultra-high dose rate pulsed electron beams up to a DPP of 11 Gy per pulse.

Electron videography of a lipid-protein tango

Biological phenomena, from enzymatic catalysis to synaptic transmission, originate in the structural transformations of biomolecules and biomolecular assemblies in liquid water. However, directly imaging these nanoscopic dynamics without probes or labels has been a fundamental methodological challenge. Here, we developed an approach for "electron videography"-combining liquid phase electron microscopy with molecular modeling-with which we filmed the nanoscale structural fluctuations of individual, suspended, and unlabeled membrane protein nanodiscs in liquid. Systematic comparisons with biochemical data and simulation indicate the graphene encapsulation involved can afford sufficiently reduced effects of the illuminating electron beam for these observations to yield quantitative fingerprints of nanoscale lipid-protein interactions. Our results suggest that lipid-protein interactions delineate dynamically modified membrane domains across unexpectedly long ranges. Moreover, they contribute to the molecular mechanics of the nanodisc as a whole in a manner specific to the protein within. Overall, this work illustrates an experimental approach to film, quantify, and understand biomolecular dynamics at the nanometer scale.

A complementary method with PFBBr-derivatization based on a GC-EI-MS platform for the simultaneous quantitation of short-, medium- and long-chain fatty acids in murine plasma and feces samples

Fatty acids (FAs) are essential molecules in all organisms and are involved in various physiological and pathophysiological processes. Pentafluorobenzyl bromide (PFBBr) is commonly used for FA derivatization for gas chromatography-mass spectrometry (GC-MS) quantification by chemical ionization (CI). While CI is the conventional ionization mode for PFBBr derivatization, the electron ionization (EI) source has also demonstrated efficacy in achieving satisfactory analytical performance for the analysis of PFB esters. In this study, we present a novel approach utilizing PFBBr-derivatization on a GC-EI-MS platform to quantitatively analyze a comprehensive range of 44 fatty acids (FAs) spanning from C2 to C24. The method's sensitivity, precision, accuracy, linearity, recovery, and matrix effect were rigorously validated against predetermined acceptance criteria. In comparison to the conventional CI ionization mode, the utilization of PFBBr-derivatization in GC-EI-MS exhibits a wider range of applications and achieves comparable sensitivity levels to the conventional CI platform. By using this method, we successfully quantified 44 FAs in plasma and feces samples from the mice with deoxynivalenol (DON)-induced kidney injury. Among these, the levels of most FA species were increased in the DON-exposure group compared with the control group. The orthogonal partial least squares discriminant analysis (OPLS-DA) of all the tested FAs showed a visual separation of the two groups, indicating DON exposure resulted in a disturbance of the FA profile in mice. These results indicate that the established method by integration of GC-MS with PFBBr derivatization is an efficient approach to quantify the comprehensive FA profile, which includes short-, medium- and long-chain FAs. In addition, our study provides new insights into the mechanism underlying DON exposure-induced kidney injury.

Electron plasma diagnostics in ELTRAP by electron cyclotron resonance heating method

Electron cyclotron resonance heating method of Particle-in-Cell code was used to analyze heating phenomena, axial kinetic energy, and self-consistent electric field of confined electron plasma in ELTRAP device by hydrogen and helium background gases. The electromagnetic simulations were performed at a constant power of 3.8 V for different RF drives (0.5 GHz- 8 GHz), as well as for 1 GHz constant frequency at these varying amplitudes (1 V-3.8 V). The impacts of axial and radial temperatures were found maximum at 1.8 V and 5 GHz as compared to other amplitudes and frequencies for both background gases. These effects are higher at varying radio frequencies due to more ionization and secondary electrons production and maximum recorded radial temperature for hydrogen background gas was 170.41 eV. The axial kinetic energy impacts were found more effective in the outer radial part (between 0.03 and 0.04 meters) of the ELTRAP device due to applied VRF through C8 electrode. The self-consistent electric field was found higher for helium background gas at 5 GHz RF than other amplitudes and radio frequencies. The excitation and ionization rates were found to be higher along the radial direction (r-axis) than the axial direction (z-axis) in helium background gas as compared to hydrogen background gas. The current studies are advantageous for nuclear physics applications, beam physics, microelectronics, coherent radiation devices and also in magnetrons.

MmcA is an electron conduit that facilitates both intracellular and extracellular electron transport in Methanosarcina acetivorans

Methanogens are a diverse group of Archaea that obligately couple energy conservation to the production of methane. Some methanogens encode alternate pathways for energy conservation, like anaerobic respiration, but the biochemical details of this process are unknown. We show that a multiheme c-type cytochrome called MmcA from Methanosarcina acetivorans is important for intracellular electron transport during methanogenesis and can also reduce extracellular electron acceptors like soluble Fe3+ and anthraquinone-2,6-disulfonate. Consistent with these observations, MmcA displays reversible redox features ranging from -100 to -450 mV versus SHE. Additionally, mutants lacking mmcA have significantly slower Fe3+ reduction rates. The mmcA locus is prevalent in members of the Order Methanosarcinales and is a part of a distinct clade of multiheme cytochromes that are closely related to octaheme tetrathionate reductases. Taken together, MmcA might act as an electron conduit that can potentially support a variety of energy conservation strategies that extend beyond methanogenesis.

Enhancing AsH3 Detoxification via Electron-Deficient [NiIII-OH (μ-O)] in a Nickel-Modified NaY Zeolite: A Pathway toward As0 Products

The transformation of toxic arsine (AsH3) gas into valuable elemental arsenic (As0) from industrial exhaust gases is important for achieving sustainable development goals. Although advanced arsenic removal catalysts can improve the removal efficiency of AsH3, toxic arsenic oxides generated during this process have not received adequate attention. In light of this, a novel approach for obtaining stable As0 products was proposed by performing controlled moderate oxidation. We designed a tailored Ni-based catalyst through an acid etching approach to alter interactions between Ni and NaY. As a result, the 1Ni/NaY-H catalyst yielded an unprecedented proportion of As0 as the major product (65%), which is superior to those of other reported catalysts that only produced arsenic oxides. Density functional theory calculations clarified that Ni species changed the electronic structure of oxygen atoms, and the formed [NiIII-OH (μ-O)] active centers facilitated the adsorption of AsH2*, AsH*, and As* reaction intermediates for As-H bond cleavage, thereby decreasing the direct reactivity of oxygen with the arsenic intermediates. This work presents pioneering insights into inhibiting excessive oxidation during AsH3 removal, demonstrating potential environmental applications for recovery of As0 from toxic AsH3.

A genetic engineering strategy to enhance outer membrane vesicle-mediated extracellular electron transfer of Geobacter sulfurreducens

Bioelectrochemical systems (BESs) are unique devices that harness the metabolic activity of electroactive microorganisms (EAMs) to convert chemical energy stored in organic substrates into electrical energy. Enhancing electron transfer efficiency between EAMs and electrodes is the key to practical implementation of BESs. Considering the role of outer membrane vesicles (OMVs) in mediating electron transfer of EAMs, a genetic engineering strategy to achieve OMVs overproduction was explored to enhance electron transfer efficiency and the underlying mechanisms were investigated. This study constructed a mutant strain of Geobacter sulfurreducens that lacked the ompA gene encoding an outer membrane protein. Experimental results showed that the mutant strain produced more OMVs and possessed higher electron transfer efficiency in Fe(III) reduction, dye degradation and current generation in BESs than the wild-type strain. More cargoes such as c-type cytochromes, functional proteins, eDNA, polysaccharides and signaling molecules that might be favorable for electron transfer and biofilm formation were found in OMVs produced by ompA-deficient anodic biofilm, which possibly contributed to the improved electron transfer efficiency of ompA-deficient biofilm. The results indicate that overproduction of OMVs in EAMs might be a potential strategy to enhance BESs performance.

All-solid-state Z-scheme ZnFe-LDH/rGO/g-C3N5 heterojunction for enhanced sonophotocatalytic degradation of ciprofloxacin: Performance and mechanistic insights

The fabrication of all-solid-state Z-scheme sonophotocatalysts is vital for improving the transfer rate of photogenerated electrons to remove antibiotics present in wastewater. Herein, a novel indirect Z-scheme ZnFe-layered double hydroxide (LDH)/reduced graphene oxide (rGO)/graphitic carbon nitride (g-C3N5) heterojunction was synthesized using a simple strategy. The ZnFe-LDH/rGO/g-C3N5 (ZF@rGCN) ternary composites were systematically characterized using different techniques. Results revealed that the 15%ZF@rGCN catalyst achieved a ciprofloxacin (CIP) degradation efficiency of 95% via the synergistic effect of sonocatalysis and photocatalysis. The improved sonophotocatalytic performance of the ZF@rGCN heterojunction was attributed to an increase in the number of active sites, a Z-scheme charge-transfer channel in ZF@rGCN, and an extended visible light response range. The introduction of rGO further enhanced the charge-transfer rate and preserved the reductive and oxidative sites of the ZF@rGCN system, thereby affording additional reactive species to participate in CIP removal. In addition, owing to its unique properties, rGO possibly increased the absorption of incident light and served as an electronic bridge in the as-formed ZF@rGCN catalyst. Finally, the possible CIP degradation pathways and the sonophotocatalytic Z-scheme charge-migration route of ZF@rGCN were proposed. This study presents a new approach for fabricating highly efficient Z-scheme sonophotocatalysts for environmental remediation.

Phase Identification and Discovery of an Elusive Polymorph of Drug-Polymer Inclusion Complex Using Automated 3D Electron Diffraction

3D electron diffraction (3D ED) has shown great potential in crystal structure determination in materials, small organic molecules, and macromolecules. In this work, an automated, low-dose and low-bias 3D ED protocol has been implemented to identify six phases from a multiple-phase melt-crystallisation product of an active pharmaceutical ingredient, griseofulvin (GSF). Batch data collection under low-dose conditions using a widely available commercial software was combined with automated data analysis to collect and process over 230 datasets in three days. Accurate unit cell parameters obtained from 3D ED data allowed direct phase identification of GSF Forms III, I and the known GSF inclusion complex (IC) with polyethylene glycol (PEG) (GSF-PEG IC-I), as well as three minor phases, namely GSF Forms II, V and an elusive new phase, GSF-PEG IC-II. Their structures were then directly determined by 3D ED. Furthermore, we reveal how the stabilities of the two GSF-PEG IC polymorphs are closely related to their crystal structures. These results demonstrate the power of automated 3D ED for accurate phase identification and direct structure determination of complex, beam-sensitive crystallisation products, which is significant for drug development where solid form screening is crucial for the overall efficacy of the drug product.

Magnetite alleviating calcification of anaerobic granular sludge (AnGS): Electron transfer enhancement and ion competition

Calcification accompanied by deactivation of anaerobic granular sludge (AnGS) is a continuing challenge for high calcium wastewater treatment. The interaction between Ca2+ and extracellular polymeric substances (EPS) is a precondition for this problem. In this study, magnetite for activity recovery and calcification alleviation simultaneously of AnGS under high calcium stress was investigated. The results showed that, in the presence of magnetite, the relative biogas production increased by 13.2 % with the higher activities of key enzymes involved in methanogenesis. Methanosarcina turned into the dominant methanogens, and syntrophic bacteria such as Chloroflexi, Synergistota were enriched, which indicated the enhancement of electron transfer by magnetite, supported by an 18 % increase of the electron transfer system (ETS) activity. Further characterizations of AnGS suggested that the granule calcification was alleviated with a final decrease of 13-40 % calcium content of AnGS with particle size of 1-2.5 mm. Besides, calcium was partially substituted by iron in the EPS, and the secretion of EPS especially proteins decreased. Batch tests demonstrated the competition between Fe2+ dissolved from magnetite and Ca2+, which interfered the interaction between Ca2+ and EPS, so the granule calcification was prevented. Therefore, magnetite played a pluripotent role in the alleviation of granule calcification and deactivation in situ via (1) enhancing electron transfer, and (2) blocking the complex between Ca2+ and EPS. This study provides a novel insight into the application of conductive metal materials in biological wastewater treatment systems suffering from high calcium attack.