Modified Donor End Caps for Binary-to-Ternary WORM Memory Conversion in N-Heteroaromatic Systems

A series of novel A-π-D type organic small molecules have been designed, synthesized, and demonstrated for non-volatile resistive switching WORM memory application. The electron-deficient phenazine and quinoxaline units were coupled with various functionalized triphenylamine end caps to explore the structure-property correlations. The photophysical investigations displayed considerable intramolecular charge transfer, and the electrochemical analysis revealed an optimum band gap of 2.44 to 2.83 eV. These factors and the thin film morphological studies suggest the feasibility of the compounds as better resistive memory devices. All the compounds indicated potent non-volatile resistive switching memory capabilities with ON/OFF ratios ranging from 103 to 104, and the lowest threshold voltage recorded stands at -0.74 V. A longer retention time of 103 s marks the substantial stability of the devices. The phenazine-based compounds outperformed the others in terms of memory performance. Exceptionally, the compound with -CHO substituted triphenylamine exhibited ternary memory performance owing to its multiple traps. The resistive switching mechanism for the devices was validated using density functional theory calculations, which revealed that the integrated effect of charge transfer and charge trapping contributes significantly to the resistive switching phenomena.

Tweaking the Non-Volatile Write-Once-Read-Many-Times (WORM) Memory using Donor-Acceptor Architecture with Isatin as Core Acceptor

Organic memory devices have attracted attention because they promise flexible electronics, low manufacturing costs, and compatibility with large-scale integration. A series of new D-A architectures were synthesized employing different donor groups and the isatin moiety as the acceptor through Suzuki-Miyaura coupling reactions. Strong intramolecular interactions were observed in the synthesized compounds, further corroborated by an optimal bandgap. The SEM investigation confirmed good molecular ordering and superior thin film surface coverage. All the compounds demonstrated notable binary Write-Once-Read-Many-Times (WORM) memory behaviour. The threshold switching voltage for these D-A systems ranged from -0.79 to -2.37 V, with the compound having isobutyl substituent showing the lowest threshold voltage and maximum ON/OFF ratio of 102, thus outperforming others. The combined effects of charge transfer and charge trapping are responsible for the resistive switching mechanism prevailing in these systems. The alterations in D-A molecules that affect molecular packing, thin film morphology, and, finally, the memory performance of the active layer are highlighted in this work.

Inherent D-A Architecture in Indoloquinoxalines with an Array of Substituents for Non-Volatile Memory Device Applications

Donor-acceptor (D-A)-based architecture has been the key to increase storage capability efficiency through the enhanced charge transportation in the fabricated device. We have designed and synthesized a series of functionalized indoloquinoxalines (IQ) for non-volatile organic memory devices. The investigation on UV-visible spectra reveals the absorption maxima of the compounds around 420 nm, attributed to the intramolecular charge transfer between indole and quinoxaline moiety. The irreversible anodic peak in the 1.0 to 1.5 V range indicates the indole moiety's oxidation ability. Besides, the cathodic peak in the range of -0.5 to -1.0 V, contributed to the stability of the reduced quinoxaline unit. All the compounds exhibited uniformly covered thin film in SEM analysis, potentially facilitating the seamless charge carrier migration between adjacent molecules. The methoxyphenyl substituted compound exhibited the binary write-once read-many (WORM) memory behavior with the lowest threshold voltage of -0.81 V. The molecular simulations displayed the efficient intramolecular charge transfer, providing the fabricated device's distinctive conductive states. Except for the tert-butylphenyl compound, which showed volatile dynamic random-access memory (DRAM) behavior, all the other compounds exhibited non-volatile WORM memory behavior, suggesting IQs potential as an intrinsic D-A molecule in organic memory devices on further structural refinement.

Efficient ternary WORM memory devices from quinoline-based D-A systems by varying the redox behavior of ferrocene

The design and synthesis of ferrocene-functionalized organic small molecules using quinoline cores are rendered to achieve a ternary write-once-read-many (WORM) memory device. Introducing an electron-withdrawing group into the ferrocene system changes the compounds' photophysical, electrochemical, and memory behavior. The compounds were synthesized with and without an acetylene bridge between the ferrocene unit and quinoline. The electrochemical studies proved the oxidation behavior with a slightly less intense reduction peak of the ferrocene unit, demonstrating that quinolines have more reducing properties than ferrocene with bandgaps ranging from 2.67-2.75 eV. The single crystal analysis of the compounds also revealed good interactive interactions, ensuring good molecular packing. This further leads to a ternary WORM memory with oxidation of the ferrocene units and charge transfer in the compounds. The devices exhibit on/off ratios of 104 and very low threshold voltages of -0.58/-1.02 V with stabilities of 103 s and 100 cycles of all the states through retention and endurance tests.

Tailoring the Resistive Switching WORM Memory Behavior of Functionalized Bis(triphenylamine)

To better understand the structure-property relationship and the significance of the donor-acceptor (D-A) system in resistive memory devices, a series of new organic small molecules with A-π-D-π-A- and D-π-D-π-D-based architecture comprising a bis(triphenylamine) core unit and ethynyl-linked electron donor/acceptor arms were designed and synthesized. The devices with A-π-D-π-A structures exhibited write-once-read-many memory behavior with a good retention time of 1000 s while those based on D-π-D-π-D molecules presented only conductor property. The compound with nitrophenyl substitution resulted in a higher ON/OFF current ratio of 10⁴, and the fluorophenyl substitution exhibited the lowest threshold voltage of -1.19 V. Solubility of the compounds in common organic solvents suggests that they are promising candidates for economic solution-processable techniques. Density functional theory calculations were used to envision the frontier molecular orbitals and to support the proposed resistive switching mechanisms. It is inferred that the presence of donor/acceptor substituents has a significant impact on the highest occupied molecular orbital-lowest unoccupied molecular orbital energy levels of the molecules, which affects their memory-switching behavior and thus suggests that a D-A architecture is ideal for memory device resistance switching characteristics.

Enhancing the Resistive Switching Behavior of WORM Memory Devices Using D-π-A Based Ester-Flanked Quinolines

Donor-Acceptor systems are highly appreciated in the field of organic memory devices due to their efficient charge transport within the systems. In this work, we have designed and synthesized a D-π-A system constituting ester-flanked quinolines and functionalized triarylamines (TAA) through a single-step cross-coupling reaction to fabricate memory devices via Write-Once Read-Many times (WORM) non-volatile memory. Structure-property relationships are reconnoitered for these conjugated D-π-A systems through a series of UV, fluorescence, XRD, DFT, and memory characterizations. The UV and CV data show efficient charge transfer with intramolecular charge transfer occurring at 407-417 nm and a short band gap of 2.56-2.65 eV. An enhancement in the resistive switching behavior of the memory devices is observed for the compounds with simple TAA-quinoline and tert-butylphenyl substituted TAA and fluorophenyl substituted quinoline due to balanced charge distribution in the compounds. This enhanced switching induces an on/off ratio of 10³ by generating a highly ordered arrangement in the thin films. The HOMO, LUMO levels, and the ESP images together estimate a charge transfer and charge trapping as the plausible mechanism for the solution-processable WORM memory devices. The longer retention time (10³  s) and lower threshold voltages (-1.21--2.12 V) of the devices makes them intriguing compounds for memory applications.

High-Performance Organic Field-effect Transistors from Functionalized Zinc Meso-Porphyrins

A series of new zinc porphyrins were synthesized, and their charge transport property was tuned by introducing various groups. Triarylamine was introduced to the porphyrin moiety at the meso-position as an electron donor, enhancing the charge carrier mobility. All the synthesized zinc porphyrins are thermally stable with a decomposition temperature over 178 °C. High frontier molecular orbitals levels of these compounds make them stable donor materials. SEM analysis of zinc porphyrins fabricated by spin-coating resulted in diversely self-assembled films. Field-effect transistors were fabricated using bottom-gate/top-contact architecture (BGTC) by solution-processable technique. The higher charge carrier mobility of 5.17 cm² /Vs with on/off of 10⁶ was obtained for trifluoromethyl substituted compound due to better molecular packing. In addition, GIXRD analysis revealed zinc porphyrins films crystalline nature, which supports its better charge carrier mobility. The present investigation has validated that zinc porphyrin building blocks are an attractive candidate for p-channel OFET devices.

High mobility and ON/OFF ratio of solution-processable p-channel OFETs from arylacetylene end-capped alkoxyphenanthrenes

New arylacetylene end-capped alkoxyphenanthrenes were synthesized and demonstrated as the best active layer for solution-processable p -channel organic field-effect transistors. The alkoxy chain embedded compounds exhibited enhanced solubility and induced non-covalent interactions resulting in effective molecular packing. The 'Lewis soft' heteroatoms direct the most stable conformation with dihedral angles possible for molecular interactions, and energy levels. DFT studies supported the finetuning of FMOs, with high HOMO levels ~-5.2 eV ensuring a low barrier for charge injection. OFET devices exhibited a maximum charge carrier mobility up to 1.30 cm 2 /Vs with the highest ON/OFF ratio of 10 7 . The strong π-π interactions and the crystallinity of the films are well supported by GIXRD and SEM analysis.

Biofilm-Associated Agr and Sar Quorum Sensing Systems of Staphylococcus aureus Are Inhibited by 3-Hydroxybenzoic Acid Derived from Illicium verum

Biofilm-producing Staphylococcus aureus (S. aureus) is less sensitive to conventional antibiotics than free-living planktonic cells. Here, we evaluated the antibiofilm activity of Illicium verum (I. verum) and one of its constituent compounds 3-hydroxybenzoic acid (3-HBA) against multi-drug-resistant S. aureus. We performed gas chromatography-mass spectroscopy (GC-MS) to identify the major constituents in the methanolic extract of I. verum. Ligand-receptor interactions were studied by molecular docking, and in vitro investigations were performed using crystal violet assay, spreading assay, hemolysis, proteolytic activity, and growth curve analysis. The methanolic extract of I. verum inhibited S. aureus at 4.8 mg/mL, and GC-MS analysis revealed anethole, m-methoxybenzaldehyde, and 3-HBA as the major constituents. Molecular docking attributed the antibiofilm activity to an active ligand present in 3-HBA, which strongly interacted with the active site residues of AgrA and SarA of S. aureus. At a subinhibitory concentration of 2.4 mg/mL, the extract showed biofilm inhibition. Similarly, 3-HBA inhibited biofilm activity at 25 μg/mL (90.34%), 12.5 μg/mL (77.21%), and 6.25 μg/mL (62.69%) concentrations. Marked attrition in bacterial spreading was observed at 2.4 mg/mL (crude extract) and 25 μg/mL (3-HBA) concentrations. The methanol extract of I. verum and 3-HBA markedly inhibited β-hemolytic and proteolytic activities of S. aureus. At the lowest concentration, the I. verum extract (2.4 mg/mL) and 3-HBA (25 μg/mL) did not inhibit bacterial growth. Optical microscopy and SEM analysis confirmed that I. verum and 3-HBA significantly reduced biofilm dispersion without disturbing bacterial growth. Together, we found that the antibiofilm activity of I. verum and 3-HBA strongly targeted the Agr and Sar systems of S. aureus.

An Intelligent Telugu Handwritten Character Recognition using Multi-Objective Mayfly Optimization with Deep Learning Based DenseNet Model

Handwritten character recognition process has gained significant attention among research communities due to the application in assistive technologies for visually impaired people, human robot interaction, automated registry for business document, and so on. Handwritten character recognition of Telugu language is hard owing to the absence of massive dataset and trained convolution neural network (CNN). Therefore, this paper introduces an intelligent Telugu character recognition using multi-objective mayfly optimization with deep learning (MOMFO-DL) model. The proposed MOMFO-DL technique involves DenseNet-169 model as a feature extractor to generate a useful set of feature vectors. Moreover, functional link neural network (FLNN) is used as a classification model to recognize and classify the printer characters. The design of MOMFO technique for the parameter optimization of DenseNet model and FLNN model shows the novelty of the work. The use of MOMFO technique helps to optimally tune the parameters in such a way that the overall performance can be improved. The extensive experimental analysis takes place on benchmark datasets and the outcomes are examined with respect to different measures. The experimental results pointed out the supremacy of the MOMFO technique over the recent state of art methods.

Functionalized D/A–A–D quinolines for application in solution-processable p-channel organic field-effect transistors

New functionalized quinolines with a D/A–A–D architecture and pi-end-groups at terminals were designed and synthesized. OFETs fabricated from compounds with a D–A–D architecture exhibited p-channel transistor characteristics with high hole mobilities.

'Practical management of suspected hypersensitivity reactions to anti-tuberculosis drugs.'

Tuberculosis (TB) is the commonest cause of death by a single infectious agent globally and ranks amongst the top ten causes of global mortality. The incidence of TB is highest in Low-Middle Income countries (LMICs). Prompt institution of, and compliance with, therapy are cornerstones for a favourable outcome in TB and to mitigate the risk of multiple drug resistant (MDR)-TB, which is challenging to treat. There is some evidence that adverse drug reactions (ADRs) and hypersensitivity reactions (HSRs) to anti-TB drugs occur in over 60% and 3-4% of patients respectively. Both ADRs and HSRs represent significant barriers to treatment adherence and are recognised risk factors for MDR-TB. HSRs to anti-TB drugs are usually cutaneous and benign, occur within few weeks after commencement of therapy and are likely to be T-cell mediated. Severe and systemic T-cell mediated HSRs and IgE mediated anaphylaxis to anti-TB drugs are relatively rare, but important to recognise and treat promptly. T-cell mediated HSRs are more frequent amongst patients with co-existing HIV infection. Some patients develop multiple sensitisation to anti-TB drugs. Whilst skin tests, patch tests and in vitro diagnostics have been used in the investigation of HSRs to anti-TB drugs, their predictive value is not established, they are onerous, require specialist input of an allergist and are resource-dependent. This is compounded by the global, unmet demand for allergy specialists, particularly in low income countries (LICs) / LMICs and now the challenging circumstances of the SARS-CoV-2 pandemic. This narrative review provides a critical analysis of the limited published evidence on this topic and proposes a cautious and pragmatic approach to optimise and standardise the management of HSRs to anti-TB drugs. This includes clinical risk stratification and a dual strategy involving sequential re-challenge and rapid drug desensitisation. Furthermore, a concerted international effort is needed to generate real-time data on ADRs, HSRs, safety and clinical outcomes of these interventions.

Influence of π-Endcaps on the Performance of Functionalized Quinolines for p-Channel OFETs

This study investigates the influence of aryl and ethynyl linkers as well the effect of various pi-end-groups on the performance of the quinoline-based organic field-effect transistors. A series of new functionalized quinolines with D-π-A-π-D and A-π-A-π-A architectures are designed and synthesized via the Sonagashira cross-coupling reaction. All the new compounds are well characterized and their photophysical properties are studied. The bottom gate-top contact-organic field-effect transistors devices are fabricated using the spin-coating technique. By employing the pre and post-annealing technique, films with uniform surface coverage are obtained. The variation in the end-groups results in versatile packing arrangements which determine their good charge transport properties. The p-channel transistor behavior is observed for all the new compounds. Among the molecules studied, methoxyphenyl and thiophen-2-yl terminal functionalized with D-π-A-π-D architecture exhibit the higher p-channel transistor characteristics with hole mobilities of 1.39 and 1.33 cm² V^-1 s^-1 , respectively. The good charge carrier mobilities are supported by an electron-donating methoxy group and thiophene as the end-groups with high highest occupied molecular orbitals (HOMO) and lowest unoccupied molecular orbitals (LUMO) levels, extensive π-conjugation, and better self-assembly.

Butterfly-Like Triarylamines with High Hole Mobility and On/Off Ratio in Bottom-Gated OFETs

Highly π-extended butterfly-shaped triarylamine dyads with aryleneethynylene spacer were constructed using an efficient synthetic route. These aryleneethynylene-bridged dyads are highly fluorescent and exhibited high HOMO levels, and low bandgaps, which are suitable for high-performance p-type OFETs. The field-effect transistors were fabricated through a solution-processable method and exhibited promising p-type performance with field-effect mobility up to 4.3 cm² /Vs and high I_on/off of 10⁸ under ambient conditions.

Hexaarylbenzene based high-performance p-channel molecules for electronic applications

Hexaarylbenzene-based molecules find potential applications in organic electronics due to wider energy gap, high HOMO level, higher photoconductivity, electron-rich nature, and high hole-transporting property. Due to the unique propeller structure, these molecules show low susceptibility towards self-aggregation. This property can be tailored by proper molecular engineering by the incorporation of appropriate groups. Therefore, hexaarylbenzene chromophores are widely used as the materials for high-efficiency light-emitting materials, charge transport materials, host materials, redox materials, photochemical switches, and molecular receptors. This review highlights the diverse structural modification techniques used for the synthesis of symmetrical and unsymmetrical structures. Also, the potential applications of these molecules in organic light-emitting diodes, organic field-effect transistors, organic photovoltaics, organic memory devices, and logic circuits are discussed.

Experimental infection and pathology of two highly pathogenic avian influenza H5N1 viruses isolated from crow and chicken in house crows (Corvus splendens)

We investigated the experimental infection of two highly pathogenic avian influenza H5N1 viruses isolated from crow (A/crow/Assam/142119/2008) and chicken (A/chicken/Sikkim/151466/2009) in house crows (Corvus splendens). Both viruses caused infection in crows, where four out of six and three out of six crows succumbed to H5N1 infection within 11 days post challenge by crow and chicken viruses, respectively. The major clinical signs in crows were wing paralysis, circling and torticollis. The virus shedding detected from swabs was not persistent in both crow nor chicken viruses. Both viruses were isolated more frequently from oral swabs than from cloacal swabs. Both virus strains were isolated from brain, lungs, heart, liver, pancreas, spleen, large intestines of crows that succumbed to H5N1 infection. The surviving birds seroconverted in response to H5N1 virus infection. Microscopically, both viruses caused coagulative necrosis in pancreas and kidneys. Brain showed gliosis and neuronal degeneration. This experimental study highlights that crows could be infected with H5N1 viruses from different hosts with minor differences in pathogenicity. Therefore, it is imperative to carry out surveillance of highly pathogenic avian influenza H5N1 virus in synanthropic birds along with biosecurity measures to mitigate the H5N1 spread in poultry population. Keywords: chicken virus; crow virus; highly pathogenic avian influenza; house crows.

Picene and PTCDI based solution processable ambipolar OFETs

Facile and efficient solution-processed bottom gate top contact organic field-effect transistor was fabricated by employing the active layer of picene (donor, D) and N,N'-di(dodecyl)-perylene-3,4,9,10-tetracarboxylic diimide (acceptor, A). Balanced hole (0.12 cm2/Vs) and electron (0.10 cm2/Vs) mobility with Ion/off of 104 ratio were obtained for 1:1 ratio of D/A blend. On increasing the ratio of either D or A, the charge carrier mobility and Ion/off ratio improved than that of the pristine molecules. Maximum hole (µmax,h) and electron mobilities (µmax,e) were achieved up to 0.44 cm2/Vs for 3:1 and 0.25 cm2/Vs for 1:3, (D/A) respectively. This improvement is due to the donor phase function as the trap center for minority holes and decreased trap density of the dielectric layer, and vice versa. High ionization potential (- 5.71 eV) of 3:1 and lower electron affinity of (- 3.09 eV) of 1:3 supports the fine tuning of frontier molecular orbitals in the blend. The additional peak formed for the blends at high negative potential of - 1.3 V in cyclic voltammetry supports the molecular level electronic interactions of D and A. Thermal studies supported the high thermal stability of D/A blends and SEM analysis of thin films indicated their efficient molecular packing. Quasi-π-π stacking owing to the large π conjugated plane and the crystallinity of the films are well proved by GIXRD. DFT calculations also supported the electronic distribution of the molecules. The electron density of states (DOS) of pristine D and A molecules specifies the non-negligible interaction coupling among the molecules. This D/A pair has unlimited prospective for plentiful electronic applications in non-volatile memory devices, inverters and logic circuits.

Inhibition of Quorum Sensing and Biofilm Formation in Chromobacterium violaceum by Fruit Extracts of Passiflora edulis

Chromobacterium violaceum (C. violaceum) is a Gram-negative, rod-shaped facultatively anaerobic bacterium implicated with recalcitrant human infections. Here, we evaluated the anti-QS and antibiofilm activities of ethyl acetate extracts of Passiflora edulis (P. edulis) on the likely inactivation of acyl-homoserine lactone (AHL)-regulated molecules in C. violaceum both by in vitro and in silico analyses. Our investigations showed that the sub-MIC levels were 2, 1, and 0.5 mg/mL, and the concentrations showed a marked reduction in violacein pigment production by 75.8, 64.6, and 35.2%. AHL quantification showed 72.5, 52.2, and 35.9% inhibitions, inhibitions of EPS production (72.8, 36.5, and 25.9%), and reductions in biofilm formation (90.7, 69.4, and 51.8%) as compared to a control. Light microscopy and CLSM analysis revealed dramatic reduction in the treated biofilm group as compared to the control. GC-MS analysis showed 20 major peaks whose chemical structures were docked as the CviR ligand. The highest docking score was observed for hexadecanoic acid, 2-hydroxy-1-(hydroxymethyl) ethyl ester bonds in the active site of CviR with a binding energy of -8.825 kcal/mol. Together, we found that hexadecanoic acid, 2-hydroxy-1-(hydroxymethyl) ethyl ester remarkably interacted with CviR to inhibit the QS system. Hence, we concluded that hexadecanoic acid, 2-hydroxy-1-(hydroxymethyl) ethyl ester of P. edulis could likely be evaluated for treating C. violaceum infections.

High performance p-channel and ambipolar OFETs based on imidazo[4,5-f]-1,10-phenanthroline-triarylamines

A series of phenanthroline functionalized triarylamines (TAA) has been designed and synthesised to evaluate their OFET characteristics. Solution processed OFET devices have exhibited p-channel/ambipolar behaviour with respect to the substituents, in particular methoxyphenyl substitution resulted with highest mobility (μ h) up to 1.1 cm2 V-1 s-1 with good I on/off (106) ratio. These compounds can be potentially utilized for the fabrication of electronic devices.

One-pot Synthesis of 2-Hydroxy-1,4-Naphthoquinone (Lawsone)

Aims and Scope: The 2-hydroxy-1,4-naphthoquinone (lawsone) and 2,5-dihydroxy-1, 4-naphthoquninone (5-hydroxylawsone) are synthesized by one step process. The process involves an inexpensive catalyst urea hydrogen peroxide and a base (t-BuOK) in alcohol for the transformation of 1-naphthol or 2,5-dihydroxynaphthalene to lawsone or its derivatives in the presences of oxygen. The process is further directed to produce lawsone or its derivatives, with no extraneous heating to make it energetically efficient. The synthesized compounds are analyzed by FT-IR, 1H and 13C NMR spectral studies.

MATERIALS AND METHODS

All the raw materials were purchased from commercial suppliers and used as such without further purification. The infrared spectra were recorded on a Thermo Nicolet-Avatar-330 FT-IR spectrophotometer using KBr (pellets) and noteworthy absorption values (cm-1) are obtained. 1H and 13C NMR spectra are recorded at 293K on BRUKER AMX-400 Spectrometer operating with the frequencies of 300 MHz and 75, 125 MHz respectively using DMSO-d6 as solvent.

RESULTS

The 2-hydroxy-1,4-naphthoquinone (lawsone) and 2,5-dihydroxy-1,4-naphthoquninone (5- hydroxylawsone) are synthesised from 1-naphthol and 1,5-dihydorxynaphalene with urea-hydrogen peroxide as the catalyst in basic medium and oxygen as the oxidizing agent. After purification, the formed products are analysed by IR and NMR spectroscopy. The yield is 82% and the purity of the products is > 95%.

CONCLUSION

The present study highlights the process for the manufacturing of lawsone and its derivatives which is efficient in terms of energy needed for the activation of products from reactants. The advantages include its cost-effective nature in terms of simple inexpensive catalyst required for the process and high yield. The mild reaction conditions employed and the harmless by product obtained further confirm the usefulness of this synthetic process.

Label-free peptide nucleic acid biosensor for visual detection of multiple strains of influenza A virus suitable for field applications

Accurate and rapid diagnosis of Influenza A viruses (IAVs) is challenging because of multiple strains circulating in humans and animal populations, and the emergence of new strains. In this study, we demonstrate a simple and rapid strategy for visual detection of multiple strains of IAVs (H1 to H16 subtypes) using peptide nucleic acid (PNA) as a biosensor and unmodified gold nanoparticles (AuNPs) as a reporter. The design principle of the assay is based on the color change on account of free PNA-induced aggregation of AuNPs in the presence of non-complementary viral RNA sequence and vice-versa. The assay could detect IAV RNA with a visual limit of detection of 2.3 ng. The quantification of RNA with a considerable accuracy on a simple spectrophotometer was achieved on plotting the PNA-induced colorimetric changes (absorption ratio of A₆₄₀/A₅₂₀) in the presence of a varying concentration of complementary RNA. As a proof-of-concept, the visual assay was validated on 419 avian clinical samples and receiver operating characteristic (ROC) curve analysis showed a high diagnostic specificity (96.46%, 95% CI = 93.8 to 98.2) and sensitivity (82.41%, 95% CI = 73.9 to 89.1) when RT-qPCR was used as reference test. Hence, the simplicity, rapidity, and universality of this strategy make it a potential candidate visual assay for clinical diagnosis and surveillance of IAVs, especially in the resource-limited settings. The proposed strategy establishes new avenues for developing a simple and rapid diagnostic system for viral infections and biomolecules.

Design, Synthesis, DNA/HSA Binding, and Cytotoxic Activity of Half-Sandwich Ru(II)-Arene Complexes Containing Triarylamine-Thiosemicarbazone Hybrids

Organoruthenium complexes are potent alternatives for platinum-based complexes because of their superior anticancer activity. In this investigation, a series of new Ru(II)-arene complexes with triarylamine-thiosemicarbazone hybrid ligands with higher anticancer activity than cisplatin are reported. The molecular structure of the ligands and complexes was confirmed spectroscopically and supported by single-crystal X-ray crystallography. These complexes adopted a three-leg piano stool geometry. All the Ru(II)-arene complexes were systematically investigated for their in vitro cytotoxicity against human cervical (HeLa S3), lung (A549) cancer, and human normal lung (IMR-90) cell lines using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Interestingly, a pyrrolidine-attached Ru(II)-benzene complex exhibited superior activity against cancer cells with low IC₅₀ values, and colony formation study showed complete inhibition at 5 and 10 μM concentration. Furthermore, morphological changes assessed by acridine orange and propidium iodide staining revealed that the cell death occurred by apoptosis. In addition, the interaction between synthesized Ru(II)-arene complexes and DNA/protein was explored by absorption and emission spectroscopy methods. These synthesized new organoruthenium complexes can be used for developing new metal-based anticancer drugs.

Kinetics and mechanism of the oxidation of alkenes by chromium(VI) in the presence of complexing agents

The catalytic activities of 2,2′-bipyridyl (bipy) and oxalic acid (Oxa) in the HCrO4– oxidation of some substituted trans-cinnamic acids have been investigated in acidic solutions. The Cr(VI)–bipy and Cr(VI)–Oxa complexes are believed to be the probable reactive electrophiles in this redox process. The kinetic data reveal that electron-releasing groups enhance the reactivity to a significant extent while the electron-withdrawing ones reduce the rate marginally. It appears that the mechanism of bipy/Oxa catalysed chromium(VI) oxidation of unsaturated systems to the corresponding cleavage products involves an electrophilic attack of the reactive complex at the C–C double bond. The formation of a ternary complex as an intermediate is envisaged to describe the redox process. In this paper, we also report on the kinetic form of the oxidation of trans-stilbene to methyl 3-hydroxy-2,3-diphenylpropanoate. The mechanistic pathway has been determined based on the kinetic behaviour and the product assignment.

Ag-doped ZnO nanorods embedded reduced graphene oxide nanocomposite for photo-electrochemical applications

In this paper, the Ag-doped zinc oxide nanorods embedded reduced graphene oxide (ZnO:Ag/rGO) nanocomposite was synthesized for photocatalytic degradation of methyl orange (MO) in the water. The microstructural results confirmed the successful decoration of Ag-doped ZnO nanorods on rGO matrix. The photocatalytic properties, including photocatalytic degradation, charge transfer kinetics and photocurrent generation, are systematically investigated using electrochemical impedance spectroscopy (EIS), photocurrent transient response (PCTR) and open circuit voltage decay (OCVD). The results of photocatalytic dye degradation measurements indicated that ZnO:Ag/rGO nanocomposite is more effective than pristine ZnO to degrade the MO dye, and the degradation rate reached 40.6% in 30 min. The decomposition of MO with ZnO:Ag/rGO nanostructure followed first-order reaction kinetics with a reaction rate constant (K a) of 0.01746 min-1. The EIS, PCTR and OCVD measurements revealed that the Ag doping and incorporation of rGO could suppress the recombination probability in ZnO by the separation of photo-generated electron-hole pairs, which leads to the enhanced photocurrent generation and photocatalytic activity. The photocurrent density of ZnO:Ag/rGO, ZnO/rGO and pristine ZnO are 206, 121.4 and 88.8 nA cm-2, respectively.

Three-dimensional hydrogen bonding between Landers and planar molecules facilitated by electrostatic interactions with Ni adatoms

Using a combination of UHV-STM and molecular mechanics calculations, we investigate the surface self-assembly of a complex multi-component metal-molecule system with synergistic non-covalent interactions. Hydrogen bonding between three-dimensional Lander-DAT molecules and planar PTCDI molecules, adsorbed closer to the surface, is found to be facilitated by electrostatic interactions between co-adsorbed Ni adatoms and the flexible molecular DAT groups.

Norfloxacin salts of carboxylic acids curtail planktonic and biofilm mode of growth in ESKAPE pathogens

AIMS

To enhance the antimicrobial and antibiofilm activity of norfloxacin against the planktonic and biofilm mode of growth in ESKAPE pathogens using chemically modified norfloxacin salts.

METHODS AND RESULTS

Antimicrobial testing, synergy testing and time-kill curve analysis were performed to evaluate antibacterial effect of norfloxacin carboxylic acid salts against ESKAPE pathogens. In vivo efficacy to reduce bacterial bioburden was evaluated in zebrafish infection model. Crystal violet assay and live-dead staining were performed to discern antibiofilm effect. Membrane permeability, integrity and molecular docking studies were carried out to ascertain the mechanism of action. The carboxylic acid salts, relative to parent molecule norfloxacin, displayed two- to fourfold reduction in minimum inhibitory concentration against Staphylococcus aureus and Pseudomonas aeruginosa, in addition to displaying potent bacteriostatic effect against certain members of ESKAPE pathogens. In vivo treatments revealed that norfloxacin tartrate (SRIN2) reduced MRSA bioburden by greater than 1 log fold relative to parent molecule in the muscle tissue. In silico docking with gyrA of S. aureus showed increased affinity of SRIN2 towards DNA gyrase. The enhanced antibacterial effect of norfloxacin salts could be partially accounted by altered membrane permeability in S. aureus and perturbed membrane integrity in P. aeruginosa. Antibiofilm studies revealed that SRIN2 (norfloxacin tartrate) and SRIN3 (norfloxacin benzoate) exerted potent antibiofilm effect particularly against Gram-negative ESKAPE pathogens. The impaired colonization of both S. aureus and P. aeruginosa due to improved norfloxacin salts was further supported by live-dead imaging.

CONCLUSION

Norfloxacin carboxylic acid salts can act as potential alternatives in terms of drug resensitization and reuse.

SIGNIFICANCE AND IMPACT OF THE STUDY

Our study shows that carboxylic acid salts of norfloxacin could be effectively employed to treat both planktonic- and biofilm-based infections caused by select members of ESKAPE pathogens.

Organic semiconductor/graphene oxide composites as a photo-anode for photo-electrochemical applications

An intimate physical mixture of graphene oxide (GO) and semiconducting organic molecules like bromophenathrene (BrPh) and bromopyrene (BrPy) was prepared by using a ball milling technique. The structural, microstructural, physical and chemical properties of the mixtures (20 wt% of GO) were analyzed by X-ray diffraction, SEM, FT-IR, TGA and TCSPC studies. Furthermore, the electrochemical properties like AC electrical conductivity, transient photocurrent response (PCTR) and open circuit voltage (OCVD) of the samples were analyzed. It has been observed from TCSPC and OCVD measurements that 20 wt% of GO in the semiconductor composite leads to an enhanced life-time of photo-generated charge carriers. The physical mixture composites exhibit a higher photocurrent than pure BrPh and BrPy.

New organic materials with longer life-times of the charge carrier and enhancement of photocurrent generation were developed.

Aryl fluoride functionalized graphene oxides for excellent room temperature ammonia sensitivity/selectivity

Herein, we report the covalent functionalization of graphene oxide (GO) through ‘‘click’’ reaction and its applications towards ammonia sensing. This inimitable method of covalent functionalization involves linking GO with azide moiety and click coupling of different derivatives of aryl propargyl ether, which enhances the sensitivity towards ammonia. The functionalized GO were characterized using NMR, XRD, SEM, FT-IR, Raman, UV-Vis, TGA and DSC. Compared to pristine GO, the GO functionalized with Ar samples (GO-Ar) exhibit excellent room temperature ammonia sensing properties with good response/recovery characteristics. It has been observed that 2,3-difluoro and 2,3,4-trifluoro substituted aryl propargyl ether functionalized GO (GO-Ar2 and GO-Ar3) shows superior ammonia sensing with response/recovery of 63%/∼90% and 60%/100%, respectively at 20 ppm. The GO-Ar3 exhibits high sensitivity towards ammonia at 20–100 ppm. Computational studies supports the high sensitivity of GO-Ar towards ammonia due to its high adsorption energy.

Covalent functionalization of graphene oxide (GO) through ‘‘click’’ reaction and its applications towards ammonia sensing has been demonstrated.

Survivability of low pathogenic (H9N2) avian influenza virus in water in the presence of Atyopsis moluccensis (Bamboo shrimp)

Low pathogenic avian influenza virus (LPAIV) exhibits an ecological climax with the aquatic ecosystem. The most widely prevalent subtype of LPAIV is H9N2. Wild aquatic birds being the natural reservoirs and ducks, the "Trojan horses" for Avian Influenza Virus (AIV), can contaminate the natural water bodies inhabited by them. The virus can persist in the contaminated water from days to years depending upon the environmental conditions. Various aquatic species other than ducks can promote the persistence and transmission of AIV; however, studies on the role of aquatic fauna in persistence and transmission of avian influenza virus are scarce. This experiment was designed to evaluate the survivability of H9N2 LPAIV in water with and without Atyopsis moluccensis (bamboo shrimp) for a period of 12 days. The infectivity and amount of virus in water were calculated and were found to be significantly higher in water with A. moluccensis than in water without A. moluccensis. The study also showed that A. moluccensis can accumulate the virus mechanically which can infect chicken eggs up to 11 days. The virus transmission potential of A. moluccensis requires further studies.

Infectious dose-dependent accumulation of live highly pathogenic avian influenza H5N1 virus in chicken skeletal muscle-implications for public health

Highly pathogenic avian influenza viruses (HPAIV) of H5N1 subtype are a major global threat to poultry and public health. Export of poultry products, such as chicken and duck meat, is a known source for the cross-boundary spread of HPAI H5N1 viruses. Humans get infected with HPAI H5N1 viruses either by close contact with infected poultry or through consumption of fresh/undercooked poultry meat. Skeletal muscle is the largest soft tissue in chicken that has been shown to contain virus during systemic HPAIV infection and supports productive virus infection. However, the time between infection of a chicken with H5N1 virus and presence of virus in muscle tissue is not yet known. Further, it is also not clear whether chicken infected with low doses of H5N1 virus that cause non-fatal subclinical infections continue to accumulate virus in skeletal muscle. We investigated the amount and duration of virus detection in skeletal muscle of chicken experimentally infected with different doses (10² , 10³ and 10⁴ EID₅₀ ) of a HPAI H5N1 virus. Influenza viral antigen could be detected as early as 6 hr after infection and live virus was recovered from 48 hr after infection. Notably, chicken infected with lower levels of HPAI H5N1 virus (i.e., 10² EID₅₀ ) did not die acutely, but continued to accumulate high levels of H5N1 virus in skeletal muscle until 6 days post-infection. Our data suggest that there is a potential risk of human exposure to H5N1 virus through meat from clinically healthy chicken infected with a low dose of virus. Our results highlight the need to implement rigorous monitoring systems to screen poultry meat from H5N1 endemic countries to limit the global spread of H5N1 viruses.

Quantitative imaging of anti-phase domains by polarity sensitive orientation mapping using electron backscatter diffraction

Advanced structural characterisation techniques which are rapid to use, non-destructive and structurally definitive on the nanoscale are in demand, especially for a detailed understanding of extended-defects and their influence on the properties of materials. We have applied the electron backscatter diffraction (EBSD) technique in a scanning electron microscope to non-destructively characterise and quantify antiphase domains (APDs) in GaP thin films grown on different (001) Si substrates with different offcuts. We were able to image and quantify APDs by relating the asymmetrical intensity distributions observed in the EBSD patterns acquired experimentally and comparing the same with the dynamical electron diffraction simulations. Additionally mean angular error maps were also plotted using automated cross-correlation based approaches to image APDs. Samples grown on substrates with a 4° offcut from the [110] do not show any APDs, whereas samples grown on the exactly oriented substrates contain APDs. The procedures described in our work can be adopted for characterising a wide range of other material systems possessing non-centrosymmetric point groups.

A giant testicular mixed germ cell tumour

We present a case that we believe to be the largest mixed germ cell testicular tumour reported in the United Kingdom. A 23-year-old male was admitted to our urology department with a large scrotal swelling. The patient was found to have a giant left testicular tumour and a solitary lung metastasis at presentation. He underwent an emergency radical orchidectomy and subsequently received four cycles of bleomycin, etoposide and cisplatin chemotherapy. Four months after starting treatment, the tumour markers had normalised and a repeat staging computed tomography showed no active disease. The tumour reached that size because of the patient's failure to seek medical attention due to fear and embarrassment.