Childhood trauma and the use of opioids and other prescription analgesics in adolescence and young adulthood: The HUNT Study

ABSTRACT

Opioid and nonopioid analgesics are commonly prescribed to young people to alleviate pain. Even short-term prescriptions increase the risk of persistent use and future misuse of potent analgesics, such as opioids. Childhood trauma exposure has been found to be related to pain conditions and to using more prescription analgesics. This large, prospective cohort study aimed to investigate the association of a broad range of childhood trauma exposures with prescription rates for opioid and nonopioid analgesics in adolescence and young adulthood. Self-reported data on childhood trauma exposures from adolescents (aged 13-19 years) who participated in the Young-HUNT3 Study (2006-2008, n = 8199) were linked to data from the Norwegian Prescription Database (NorPD, 2004-2021). We found that exposure to childhood trauma was consistently associated with higher prescription rates for opioids throughout adolescence and young adulthood. The highest incidence rate ratio (IRR) in adolescence was observed for sexual abuse (IRR 1.63, confidence interval [CI] 1.19-2.23). In young adulthood, the highest IRR was observed for physical violence (2.66, CI 2.27-3.12). The same overall pattern was observed for nonopioid analgesics. The more frequent prescriptions of opioid and nonopioid analgesics to participants exposed to childhood trauma suggests a higher symptom load of pain causing them to seek professional help with pain relief. Receiving potent analgesics is not without risk, and the likelihood of misuse may be elevated among trauma-exposed individuals. A trauma-informed approach to pain could be vital for guiding clinicians to the most effective and least harmful treatment for each patient.

Hydrogen Embrittlement as a Conspicuous Material Challenge─Comprehensive Review and Future Directions

Hydrogen is considered a clean and efficient energy carrier crucial for shaping the net-zero future. Large-scale production, transportation, storage, and use of green hydrogen are expected to be undertaken in the coming decades. As the smallest element in the universe, however, hydrogen can adsorb on, diffuse into, and interact with many metallic materials, degrading their mechanical properties. This multifaceted phenomenon is generically categorized as hydrogen embrittlement (HE). HE is one of the most complex material problems that arises as an outcome of the intricate interplay across specific spatial and temporal scales between the mechanical driving force and the material resistance fingerprinted by the microstructures and subsequently weakened by the presence of hydrogen. Based on recent developments in the field as well as our collective understanding, this Review is devoted to treating HE as a whole and providing a constructive and systematic discussion on hydrogen entry, diffusion, trapping, hydrogen-microstructure interaction mechanisms, and consequences of HE in steels, nickel alloys, and aluminum alloys used for energy transport and storage. HE in emerging material systems, such as high entropy alloys and additively manufactured materials, is also discussed. Priority has been particularly given to these less understood aspects. Combining perspectives of materials chemistry, materials science, mechanics, and artificial intelligence, this Review aspires to present a comprehensive and impartial viewpoint on the existing knowledge and conclude with our forecasts of various paths forward meant to fuel the exploration of future research regarding hydrogen-induced material challenges.

Beyond the Surface: A Methodological Exploration of Enzyme Impact along the Cellulose Fiber Cross-Section

Despite the wide range of analytical tools available for the characterization of cellulose, the in-depth characterization of inhomogeneous, layered cellulose fiber structures remains a challenge. When treating fibers or spinning man-made fibers, the question always arises as to whether the changes in the fiber structure affect only the surface or the entire fiber. Here, we developed an analysis tool based on the sequential limited dissolution of cellulose fiber layers. The method can reveal potential differences in fiber properties along the cross-sectional profile of natural or man-made cellulose fibers. In this analytical approach, carbonyl groups are labeled with a carbonyl selective fluorescence label (CCOA), after which thin fiber layers are sequentially dissolved with the solvent system DMAc/LiCl (9% w/v) and analyzed with size exclusion chromatography coupled with light scattering and fluorescence detection. The analysis of these fractions allowed for the recording of the changes in the chemical structure across the layers, resulting in a detailed cross-sectional profile of the different functionalities and molecular weight distributions. The method was optimized and tested in practice with LPMO (lytic polysaccharide monooxygenase)-treated cotton fibers, where it revealed the depth of fiber modification by the enzyme.

Inverse Hypercorroles

Ground-state and time-dependent density functional theory (TDDFT) calculations with the long-range-corrected, Coulomb-attenuating CAMY-B3LYP exchange-correlation functional and large, all-electron STO-TZ2P basis sets have been used to examine the potential "inverse hypercorrole" character of meso-p-nitrophenyl-appended dicyanidocobalt(III) corrole dianions. The effect is most dramatic for 5,15-bis(p-nitrophenyl) derivatives, where it manifests itself in intense NIR absorptions. The 10-aryl groups in these complexes play a modulatory role, as evinced by experimental UV-visible spectroscopic and electrochemical data for a series of 5,15-bis(p-nitrophenyl) dicyanidocobalt(III) corroles. TDDFT (CAMY-B3LYP) calculations ascribe these features clearly to a transition from the corrole's a2u-like HOMO (retaining the D4h irrep used for metalloporphyrins) to a nitrophenyl-based LUMO. The outward nature of this transition contrasts with the usual phenyl-to-macrocycle direction of charge transfer transitions in many hyperporphyrins and hypercorroles; thus, the complexes studied are aptly described as inverse hypercorroles.

Origins and Importance of Intragranular Cracking in Layered Lithium Transition Metal Oxide Cathodes

Li-ion batteries have a pivotal role in the transition toward electric transportation. Ni-rich layered transition metal oxide (LTMO) cathode materials promise high specific capacity and lower cost but exhibit faster degradation compared with lower Ni alternatives. Here, we employ high-resolution electron microscopy and spectroscopy techniques to investigate the nanoscale origins and impact on performance of intragranular cracking (within primary crystals) in Ni-rich LTMOs. We find that intragranular cracking is widespread in charged specimens early in cycle life but uncommon in discharged samples even after cycling. The distribution of intragranular cracking is highly inhomogeneous. We conclude that intragranular cracking is caused by local stresses that can have several independent sources: neighboring particle anisotropic expansion/contraction, Li- and TM-inhomogeneities at the primary and secondary particle levels, and interfacing of electrochemically active and inactive phases. Our results suggest that intragranular cracks can manifest at different points of life of the cathode and can potentially lead to capacity fade and impedance rise of LTMO cathodes through plane gliding and particle detachment that lead to exposure of additional surfaces to the electrolyte and loss of electrical contact.

Gaussians for Electronic and Rovibrational Quantum Dynamics

The assumptions underpinning the adiabatic Born-Oppenheimer (BO) approximation are broken for molecules interacting with attosecond laser pulses, which generate complicated coupled electronic-nuclear wave packets that generally will have components of electronic and dissociation continua as well as bound-state contributions. The conceptually most straightforward way to overcome this challenge is to treat the electronic and nuclear degrees of freedom on equal quantum-mechanical footing by not invoking the BO approximation at all. Explicitly correlated Gaussian (ECG) basis functions have proved successful for non-BO calculations of stationary molecular states and energies, reproducing rovibrational absorption spectra with very high accuracy. In this Article, we present a proof-of-principle study of the ability of fully flexible ECGs (FFECGs) to capture the intricate electronic and rovibrational dynamics generated by short, high-intensity laser pulses. By fitting linear combinations of FFECGs to accurate wave function histories obtained on a large real-space grid for a regularized 2D model of the hydrogen atom and for the 2D Morse potential, we demonstrate that FFECGs provide a very compact description of laser-driven electronic and rovibrational dynamics.

Experimental and Theoretical Study of the OH-Initiated Degradation of Piperidine under Simulated Atmospheric Conditions

The OH-initiated photo-oxidation of piperidine and the photolysis of 1-nitrosopiperidine were investigated in a large atmospheric simulation chamber and in theoretical calculations based on CCSD(T*)-F12a/aug-cc-pVTZ//M062X/aug-cc-pVTZ quantum chemistry results and master equation modeling of the pivotal reaction steps. The rate coefficient for the reaction of piperidine with OH radicals was determined by the relative rate method to be kOH-piperidine = (1.19 ± 0.27) × 10-10 cm3 molecule-1 s-1 at 304 ± 2 K and 1014 ± 2 hPa. Product studies show the piperidine + OH reaction to proceed via H-abstraction from both CH2 and NH groups, resulting in the formation of the corresponding imine (2,3,4,5-tetrahydropyridine) as the major product and in the nitramine (1-nitropiperidine) and nitrosamine (1-nitrosopiperidine) as minor products. Analysis of 1-nitrosopiperidine photolysis experiments under natural sunlight conditions gave the relative rates jrel = j1-nitrosoperidine/jNO2 = 0.342 ± 0.007, k3/k4a = 0.53 ± 0.05 and k2/k4a = (7.66 ± 0.18) × 10-8 that were subsequently employed in modeling the piperidine photo-oxidation experiments, from which the initial branchings between H-abstraction from the NH and CH2 groups, kN-H/ktot = 0.38 ± 0.08 and kC2-H/ktot = 0.49 ± 0.19, were derived. All photo-oxidation experiments were accompanied by particle formation that was initiated by the acid-base reaction of piperidine with nitric acid. Primary photo-oxidation products including both 1-nitrosopiperidine and 1-nitropiperidine were detected in the particles formed. Quantum chemistry calculations on the OH initiated atmospheric photo-oxidation of piperidine suggest the branching in the initial H-abstraction routes to be ∼35% N1, ∼50% C2, ∼13% C3, and ∼2% C4. The theoretical study produced an atmospheric photo-oxidation mechanism, according to which H-abstraction from the C2 position predominantly leads to 2,3,4,5-tetrahydropyridine and H-abstraction from the C3 position results in ring opening followed by a complex autoxidation, of which the first few steps are mapped in detail. H-abstraction from the C4 position is shown to result mainly in the formation of piperidin-4-one and 2,3,4,5-tetrahydropyridin-4-ol, whereas H-abstraction from N1 under atmospheric conditions primarily leads to 2,3,4,5-tetrahydropyridine and in minor amounts of 1-nitrosopiperidine and 1-nitropiperidine. The calculated rate coefficient for the piperidine + OH reaction agrees with the experimental value within 35%, and aligning the theoretical numbers to the experimental value results in k(T) = 2.46 × 10-12 × exp(486 K/T) cm3 molecule-1 s-1 (200-400 K).

Low-Dose Aspirin and Prevention of Colorectal Cancer: Evidence From a Nationwide Registry-Based Cohort in Norway

INTRODUCTION

To examine the association between low-dose aspirin use and risk of colorectal cancer (CRC).

METHODS

In this nationwide cohort study, we identified individuals aged 50 years or older residing for 6 months or more in Norway in 2004-2018 and obtained data from national registers on drug prescriptions, cancer occurrence, and sociodemographic factors. Multivariable Cox regression models were used to estimate the association between low-dose aspirin use and CRC risk. In addition, we calculated the number of CRC potentially averted by low-dose aspirin use.

RESULTS

We included 2,186,390 individuals. During the median follow-up of 10.9 years, 579,196 (26.5%) used low-dose aspirin, and 38,577 (1.8%) were diagnosed with CRC. Current use of aspirin vs never use was associated with lower CRC risk (hazard ratio [HR] 0.87, 95% confidence interval [CI] 0.84-0.90). The association was more pronounced for metastatic CRC (HR 0.79; 95% CI 0.74-0.84) than regionally advanced (HR 0.89; 95% CI 0.85-0.92) and localized CRC (HR 0.93; 95% CI 0.87-1.00; P heterogeneity = 0.001). A significant trend was found between duration of current use and CRC risk: HR 0.91 (95% CI 0.86-0.95) for <3 years, HR 0.85 (0.80-0.91) for ≥3 and <5 years, and HR 0.84 (0.80-0.88) for ≥5 years of use vs never use ( P trend < 0.001). For past use, HR were 0.89 (95% CI 0.84-0.94) for <3 years, 0.90 (0.83-0.99) for ≥3 and <5 years, and 0.98 (0.91-1.06) for ≥5 years since last use vs never use ( P -trend < 0.001). We estimated that aspirin use averted 1,073 cases of CRC (95% CI 818-1,338) in the study period.

DISCUSSION

In this nationwide cohort, use of low-dose aspirin was associated with a lower risk of CRC.

Aqueous Phase Reforming over Platinum Catalysts on Doped Carbon Supports: Exploring Platinum-Heteroatom Interactions

A series of platinum catalysts supported on carbon nanofibers with various heteroatom dopings were synthesized to investigate the effect of the local platinum environment on the catalytic activity and selectivity in aqueous phase reforming (APR) of ethylene glycol (EG). Typical carbon dopants such as oxygen, nitrogen, sulfur, phosphorus, and boron were chosen based on their ability to bring acidic or basic functional groups to the carbon surface. In situ X-ray absorption spectroscopy (XAS) was used to identify the platinum oxidation state and platinum species formed during APR of EG through multivariate curve resolution alternating least-squares analysis, observing differences in activity, selectivity, and platinum local environment among the catalysts. The platinum-based catalyst on the nitrogen-doped carbon support demonstrated the most favorable properties for H2 production due to high Pt dispersion and basicity (H2 site time yield 22.7 h-1). Direct Pt-N-O coordination was identified by XAS in this catalyst. The sulfur-doped catalyst presented Pt-S contributions with the lowest EG conversion rate and minimal production of the gas phase components. Boron and phosphorus-doped catalysts showed moderate activity, which was affected by low platinum dispersion on the carbon support. The phosphorus-doped catalyst showed preferential selectivity to alcohols in the liquid phase, associated with the presence of acid sites and Pt-P contributions observed under APR conditions.

Unraveling the (De)sodiation Mechanisms of BiFeO3 at a High Rate with Operando XRD

Development of new anode materials for Na-ion batteries strongly depends on a detailed understanding of their cycling mechanism. Due to instrumental limitations, the majority of mechanistic studies focus on operando materials' characterization at low cycling rates. In this work, we evaluate and compare the (de)sodiation mechanisms of BiFeO3 in Na-ion batteries at different current densities using operando X-ray diffraction (XRD) and ex situ X-ray absorption spectroscopy (XAS). BiFeO3 is a conversion-alloying anode material with a high initial sodiation capacity of ∼600 mAh g-1, when cycled at 0.1 A g-1. It does not change its performance or cycling mechanism, except for minor losses in capacity, when the current density is increased to 1 A g-1. In addition, operando XRD characterization carried out over multiple cycles shows that the Bi ⇋ NaBi (de)alloying reaction and the oxidation of Bi at the interface with the Na-Fe-O matrix are detrimental for cycling stability. The isolated NaBi ⇋ Na3Bi reaction is less damaging to the cycling stability of the material.

Theoretical Photoelectron Spectroscopy of Quadruple-Bonded Dimolybdenum(II,II) and Ditungsten(II,II) Paddlewheel Complexes: Performance of Common Density Functional Theory Methods

We have revisited the gas-phase photoelectron spectra of quadruple-bonded dimolybdenum(II,II) and ditungsten(II,II) paddlewheel complexes with modern density functional theory methods and obtained valuable calibration of four well-known exchange-correlation functionals, namely, BP86, OLYP, B3LYP*, and B3LYP. All four functionals were found to perform comparably, with discrepancies between calculated and experimental ionization potentials ranging from <0.1 to ∼0.5 eV, with the lowest errors observed for the classic pure functional BP86. All four functionals were found to reproduce differences in ionization potentials (IPs) between analogous Mo2 and W2 complexes, as well as large, experimentally observed ligand field effects on the IPs, with near-quantitative accuracy. The calculations help us interpret a number of differences between analogous Mo2 and W2 complexes through the lens of relativistic effects. Thus, relativity results in not only significantly lower IPs for the W2 complexes but also smaller HOMO-LUMO gaps and different triplet states relative to their Mo2 counterparts.

Using Vibrio natriegens for High-Yield Production of Challenging Expression Targets and for Protein Perdeuteration

Production of soluble proteins is essential for structure/function studies; however, this usually requires milligram amounts of protein, which can be difficult to obtain with traditional expression systems. Recently, the Gram-negative bacterium Vibrio natriegens emerged as a novel and alternative host platform for production of proteins in high yields. Here, we used a commercial strain derived from V. natriegens (Vmax X2) to produce soluble bacterial and fungal proteins in milligram scale, which we struggled to achieve in Escherichia coli. These proteins include the cholera toxin (CT) and N-acetyl glucosamine-binding protein A (GbpA) from Vibrio cholerae, the heat-labile enterotoxin (LT) from E. coli and the fungal nematotoxin CCTX2 from Coprinopsis cinerea. CT, GbpA, and LT are secreted by the Type II secretion system in their natural hosts. When these three proteins were produced in Vmax, they were also secreted and could be recovered from the growth media. This simplified the downstream purification procedure and resulted in considerably higher protein yields compared to production in E. coli (6- to 26-fold increase). We also tested Vmax for protein perdeuteration using deuterated minimal media with deuterium oxide as solvent and achieved a 3-fold increase in yield compared to the equivalent protocol in E. coli. This is good news, since isotopic labeling is expensive and often ineffective but represents a necessary prerequisite for some structural biology techniques. Thus, Vmax represents a promising host for production of challenging expression targets and for protein perdeuteration in amounts suitable for structural biology studies.

Particle-Breaking Unrestricted Hartree-Fock Theory for Open Molecular Systems

We recently introduced the particle-breaking restricted Hartree-Fock (PBRHF) model, a mean-field approach to address the fractional charging of molecules when they interact with an electronic environment. In this paper, we present an extension of the model referred to as particle-breaking unrestricted Hartree-Fock (PBUHF). The unrestricted formulation contains odd-electron states necessary for a realistic description of fractional charging. Within the PBUHF parametrization, we use two-body operators as they yield convenient operator transformations. However, two-body operators can change only the particle number by two. Therefore, we include noninteracting zero-energy bath orbitals to generate a linear combination of even and odd electron states. Depending on whether the occupied or virtual orbitals of a molecule interact with the environment, the average number of electrons is either decreased or increased. Without interaction, PBUHF reduces to the unrestricted Hartree-Fock wave function.

Transitioning from Methanol to Olefins (MTO) toward a Tandem CO2 Hydrogenation Process: On the Role and Fate of Heteroatoms (Mg, Si) in MAPO-18 Zeotypes

The tandem CO2 hydrogenation to hydrocarbons over mixed metal oxide/zeolite catalysts (OXZEO) is an efficient way of producing value-added hydrocarbons (platform chemicals and fuels) directly from CO2via methanol intermediate in a single reactor. In this contribution, two MAPO-18 zeotypes (M = Mg, Si) were tested and their performance was compared under methanol-to-olefins (MTO) conditions (350 °C, PCH3OH = 0.04 bar, 6.5 gCH3OH h-1 g-1), methanol/CO/H2 cofeed conditions (350 °C, PCH3OH/PCO/PH2 = 1:7.3:21.7 bar, 2.5 gCH3OH h-1 g-1), and tandem CO2 hydrogenation-to-olefin conditions (350 °C, PCO2/PH2 = 7.5:22.5 bar, 1.4-12.0 gMAPO-18 h molCO2-1). In the latter case, the zeotypes were mixed with a fixed amount of ZnO:ZrO2 catalyst, well-known for the conversion of CO2/H2 to methanol. Focus was set on the methanol conversion activity, product selectivity, and performance stability with time-on-stream. In situ and ex situ Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), solid-state nuclear magnetic resonance (NMR), sorption experiments, and ab initio molecular dynamics (AIMD) calculations were performed to correlate material performance with material characteristics. The catalytic tests demonstrated the better performance of MgAPO-18 versus SAPO-18 at MTO conditions, the much superior performance of MgAPO-18 under methanol/CO/H2 cofeeds, and yet the increasingly similar performance of the two materials under tandem conditions upon increasing the zeotype-to-oxide ratio in the tandem catalyst bed. In situ FT-IR measurements coupled with AIMD calculations revealed differences in the MTO initiation mechanism between the two materials. SAPO-18 promoted initial CO2 formation, indicative of a formaldehyde-based decarboxylation mechanism, while CO and ketene were the main constituents of the initiation pool in MgAPO-18, suggesting a decarbonylation mechanism. Under tandem CO2 hydrogenation conditions, the presence of high water concentrations and low methanol partial pressure in the reaction medium led to lower, and increasingly similar, methanol turnover frequencies for the zeotypes. Despite both MAPO-18 zeotypes showing signs of activity loss upon storage due to the interaction of the sites with ambient humidity, they presented a remarkable stability after reaching steady state under tandem reaction conditions and after steaming and regeneration cycles at high temperatures. Water adsorption experiments at room temperature confirmed this observation. The faster activity loss observed in the Mg version is assigned to its harder Mg2+-ion character and the higher concentration of CHA defects in the AEI structure, identified by solid-state NMR and XRD. The low stability of a MgAPO-34 zeotype (CHA structure) upon storage corroborated the relationship between CHA defects and instability.

Preventing E. coli Biofilm Formation with Antimicrobial Peptide-Functionalized Surface Coatings: Recognizing the Dependence on the Bacterial Binding Mode Using Live-Cell Microscopy

Antimicrobial peptides (AMPs) can kill bacteria by destabilizing their membranes, yet translating these molecules' properties into a covalently attached antibacterial coating is challenging. Rational design efforts are obstructed by the fact that standard microbiology methods are ill-designed for the evaluation of coatings, disclosing few details about why grafted AMPs function or do not function. It is particularly difficult to distinguish the influence of the AMP's molecular structure from other factors controlling the total exposure, including which type of bonds are formed between bacteria and the coating and how persistent these contacts are. Here, we combine label-free live-cell microscopy, microfluidics, and automated image analysis to study the response of surface-bound Escherichia coli challenged by the same small AMP either in solution or grafted to the surface through click chemistry. Initially after binding, the grafted AMPs inhibited bacterial growth more efficiently than did AMPs in solution. Yet, after 1 h, E. coli on the coated surfaces increased their expression of type-1 fimbriae, leading to a change in their binding mode, which diminished the coating's impact. The wealth of information obtained from continuously monitoring the growth, shape, and movements of single bacterial cells allowed us to elucidate and quantify the different factors determining the antibacterial efficacy of the grafted AMPs. We expect this approach to aid the design of elaborate antibacterial material coatings working by specific and selective actions, not limited to contact-killing. This technology is needed to support health care and food production in the postantibiotic era.

Investigating Polypharmacology through Targeting Known Human Neutrophil Elastase Inhibitors to Proteinase 3

Using a combination of multisite λ-dynamics (MSλD) together with in vitro IC50 assays, we evaluated the polypharmacological potential of a scaffold currently in clinical trials for inhibition of human neutrophil elastase (HNE), targeting cardiopulmonary disease, for efficacious inhibition of Proteinase 3 (PR3), a related neutrophil serine proteinase. The affinities we observe suggest that the dihydropyrimidinone scaffold can serve as a suitable starting point for the establishment of polypharmacologically targeting both enzymes and enhancing the potential for treatments addressing diseases like chronic obstructive pulmonary disease.

Performance and Sensitivity of [99mTc]Tc-sestamibi Compared with Positron Emission Tomography Radiotracers to Measure P-glycoprotein Function in the Kidneys and Liver

P-glycoprotein (P-gp, encoded in humans by the ABCB1 gene and in rodents by the Abcb1a/b genes) is a membrane transporter that can restrict the intestinal absorption and tissue distribution of many drugs and may also contribute to renal and hepatobiliary drug excretion. The aim of this study was to compare the performance and sensitivity of currently available radiolabeled P-gp substrates for positron emission tomography (PET) with the single-photon emission computed tomography (SPECT) radiotracer [99mTc]Tc-sestamibi for measuring the P-gp function in the kidneys and liver. Wild-type, heterozygous (Abcb1a/b(+/-)), and homozygous (Abcb1a/b(-/-)) Abcb1a/b knockout mice were used as models of different P-gp abundance in excretory organs. Animals underwent either dynamic PET scans after intravenous injection of [11C]N-desmethyl-loperamide, (R)-[11C]verapamil, or [11C]metoclopramide or consecutive static SPECT scans after intravenous injection of [99mTc]Tc-sestamibi. P-gp in the kidneys and liver of the mouse models was analyzed with immunofluorescence labeling and Western blotting. In the kidneys, Abcb1a/b() mice had intermediate P-gp abundance compared with wild-type and Abcb1a/b(-/-) mice. Among the four tested radiotracers, renal clearance of radioactivity (CLurine,kidney) was significantly reduced (-83%) in Abcb1a/b(-/-) mice only for [99mTc]Tc-sestamibi. Biliary clearance of radioactivity (CLbile,liver) was significantly reduced in Abcb1a/b(-/-) mice for [11C]N-desmethyl-loperamide (-47%), [11C]metoclopramide (-25%), and [99mTc]Tc-sestamibi (-79%). However, in Abcb1a/b(+/-) mice, CLbile,liver was significantly reduced (-47%) only for [99mTc]Tc-sestamibi. Among the tested radiotracers, [99mTc]Tc-sestamibi performed best in measuring the P-gp function in the kidneys and liver. Owing to its widespread clinical availability, [99mTc]Tc-sestamibi represents a promising probe substrate to assess systemic P-gp-mediated drug-drug interactions and to measure renal and hepatic P-gp function under different (patho-)physiological conditions.

Ultrafast Polarization Switching in BaTiO3 Nanomaterials: Combined Density Functional Theory and Coupled Oscillator Study

The challenge of achieving ultrafast switching of electric polarization in ferroelectric materials remains unsolved as there is no experimental evidence of such switching to date. In this study, we developed an enhanced model that describes switching within a two-dimensional space of generalized coordinates at THz pulses. Our findings indicate that stable switching in barium titanate cannot be achieved through a single linearly polarized pulse. When the intensity of the linearly polarized pulse reaches a certain threshold, the sample experiences depolarization but not stable switching. Our study also reveals that phonon friction plays a minor role in the switching dynamics and provides an estimate of the optimal parameters for the perturbing pulse with the lowest intensity that results in the depolarization of an initially polarized sample.

Integrated, Selective, Simultaneous Multigas Sensing Based on Nondispersive Infrared Spectroscopy-Type Photoacoustic Spectroscopy

Most chemical sensing scenarios require the selective and simultaneous determination of the concentrations of multiple gas species. In order to enable large-scale monitoring, reliability, robustness, and the potential for integration and miniaturization are key parameters that next-generation sensing technologies must comply with. Due to their superior sensitivity and selectivity as compared to standard NDIR-type systems, photoacoustic NDIR-approaches offer a means for selective detection at much reduced system dimensions such that microintegration becomes feasible. This contribution presents an acoustic frequency multiplexing method to integrate sensing capabilities for the parallel analysis of multiple gases in a single device without loss in selectivity via sound frequency separation. The approach is demonstrated using mid-infrared light emitting diodes and a multigas photoacoustic detector to monitor some of the most important greenhouse gases: carbon dioxide and methane. The number of gas species the sensor concept is able to detect simultaneously can be expanded without increasing the size of the system or its complexity. Additionally, the results demonstrate that the integrated device features the same selectivity and sensitivity as the currently used single gas photoacoustic NDIR systems. Furthermore, the possibility of an extension to any number of gas species is argued.

Quantum Definition of Molecular Structure

Molecular structure, a key concept of chemistry, has remained elusive from the perspective of all-particle quantum mechanics, despite many efforts. Viewing molecular structure as a manifestation of strong statistical correlation between nuclear positions, we propose a practical method based on Markov chain Monte Carlo sampling and unsupervised machine learning. Application to the D3+ molecule unambiguously shows that it possesses an equilateral triangular structure. These results provide a major step forward in our understanding of the molecular structure from fundamental quantum principles.

Kinetically-Controlled Ni-Catalyzed Direct Carboxylation of Unactivated Secondary Alkyl Bromides without Chain Walking

Herein, we report the direct carboxylation of unactivated secondary alkyl bromides enabled by the merger of photoredox and nickel catalysis, a previously inaccessible endeavor in the carboxylation arena. Site-selectivity is dictated by a kinetically controlled insertion of CO2 at the initial C(sp3)-Br site by the rapid formation of Ni(I)-alkyl species, thus avoiding undesired β-hydride elimination and chain-walking processes. Preliminary mechanistic experiments reveal the subtleties of stereoelectronic effects for guiding the reactivity and site-selectivity.

Scalar Relativistic Effects with Multiwavelets: Implementation and Benchmark

The importance of relativistic effects in quantum chemistry is widely recognized, not only for heavier elements but throughout the periodic table. At the same time, relativistic effects are strongest in the nuclear region, where the description of electrons through a linear combination of atomic orbitals becomes more challenging. Furthermore, the choice of basis sets for heavier elements is limited compared with lighter elements where precise basis sets are available. Thanks to the framework of multiresolution analysis, multiwavelets provide an appealing alternative to overcoming this challenge: they lead to robust error control and adaptive algorithms that automatically refine the basis set description until the desired precision is reached. This allows one to achieve a proper description of the nuclear region. In this work, we extended the multiwavelet-based code MRChem to the scalar zero-order regular approximation framework. We validated our implementation by comparing the total energies for a small set of elements and molecules. To confirm the validity of our implementation, we compared both against a radial numerical code for atoms and the plane-wave-based code EXCITING.

Full Breit Hamiltonian in the Multiwavelets Framework

New techniques in core-electron spectroscopy are necessary to resolve the structures of oxides of f-elements and other strongly correlated materials that are present only as powders and not as single crystals. Thus, accurate quantum chemical methods must be developed to calculate core spectroscopic properties in such materials. In this contribution, we present an important development in this direction, extending our fully adaptive real-space multiwavelet basis framework to tackle the four-component Dirac-Coulomb-Breit Hamiltonian. We show that multiwavelets can reproduce one-dimensional grid-based approaches. They are however a fully three-dimensional approach which can later be extended to molecules and materials. Our multiwavelet implementation attained precise results irrespective of the chosen nuclear model, provided that the error threshold is tight enough and that the chosen polynomial basis is sufficiently large. Furthermore, our results confirmed that in two-electron species, the magnetic and Gauge contributions from s-orbitals are identical in magnitude and can account for the experimental evidence from K and L edges.

Accurate Computation of Thermodynamic Activation Parameters in the Chorismate Mutase Reaction from Empirical Valence Bond Simulations

Chorismate mutase (CM) enzymes have long served as model systems for benchmarking new methods and tools in computational chemistry. Despite the enzymes' prominence in the literature, the extent of the roles that activation enthalpy and entropy play in catalyzing the conversion of chorismate to prephenate is still subject to debate. Knowledge of these parameters is a key piece in fully understanding the mechanism of chorismate mutases. Within this study, we utilize EVB/MD free energy perturbation calculations at a range of temperatures, allowing us to extract activation enthalpies and entropies from an Arrhenius plot of activation free energies of the reaction catalyzed by a monofunctional Bacillus subtilis CM and the promiscuous enzyme isochorismate pyruvate lyase of Pseudomonas aeruginosa. In comparison to the uncatalyzed reaction, our results show that both enzyme-catalyzed reactions exhibit a substantial reduction in activation enthalpy, while the effect on activation entropy is relatively minor, demonstrating that enzyme-catalyzed CM reactions are enthalpically driven. Furthermore, we observe that the monofunctional CM from B. subtilis more efficiently catalyzes this reaction than its promiscuous counterpart. This is supported by a structural analysis of the reaction pathway at the transition state, from which we identified key residues explaining the enthalpically driven nature of the reactions and also the difference in efficiencies between the two enzymes.

QSym2: A Quantum Symbolic Symmetry Analysis Program for Electronic Structure

Symmetry provides a powerful machinery to classify, interpret, and understand quantum-mechanical theories and results. However, most contemporary quantum chemistry packages lack the ability to handle degeneracy and symmetry breaking effects, especially in non-Abelian groups, and they are not able to characterize symmetry in the presence of external magnetic or electric fields. In this article, a program written in Rust entitled QSym2 that makes use of group and representation theories to provide symmetry analysis for a wide range of quantum-chemical calculations is introduced. With its ability to generate character tables symbolically on-the-fly and by making use of a generic symmetry-orbit-based representation analysis method formulated in this work, QSym2 is able to address all of these shortcomings. To illustrate these capabilities of QSym2, four sets of case studies are examined in detail in this article: (i) high-symmetry C84H64, C60, and B9- to demonstrate the analysis of degenerate molecular orbitals (MOs); (ii) octahedral Fe(CN)63- to demonstrate the analysis of symmetry-broken determinants and MOs; (iii) linear hydrogen fluoride in a magnetic field to demonstrate the analysis of magnetic symmetry; and (iv) equilateral H3+ to demonstrate the analysis of density symmetries.

Well-Separated Photoinduced Charge Carriers on Hydrogen Production Using NiS2/TiO2 Nanocomposites

Photocatalytic hydrogen production is a sustainable and greenhouse-gas-free method that requires an efficient and abundant photocatalyst, which minimizes energy consumption. Currently, interests in transition metal chalcogenide materials have been utilized in different applications due to their quantum confinement effect and low band gaps. In this study, different wt % of NiS2-embedded TiO2 nanocomposites were synthesized by a facile hydrothermal method and utilized for photocatalytic hydrogen production under extended solar irradiation. Among the materials studied, the highest amount (4.185 mmol g-1) of hydrogen production was observed with 15 wt % of the NiS2/TiO2 nanocomposite. The highest photocatalytic activity may be due to the well separation of photoinduced charge carriers on the catalyst, which was confirmed by the electrochemical studies. Thus, we believe that these photocatalysts are promising candidates for future applications.

10-Valence-Electron C≡O and the 14-VE C≡Pt: Two Triple-Bonded Isoelectronic Families Differing by a dδ4 Ring

10-VE A≡A' Diatomics, such as N≡N, C≡O, etc., have a strong σ2π4 triple bond plus a lone pair at each end. In our studies on 14-VE A≡B systems, such as C≡Pt, we find a similar bonding system plus a (5dδ)4 ring. Here, the A atom belongs to groups 13-17 and the B atom to groups 7-11. Also the BB' combinations, triatomics, such as PtCO or DsCO or uranyl, and longer chains, such as AuCN and [NC-Au-CN]-, are discussed. The δ ring directly contributes to nuclear quadrupole coupling constants, and DFT calculations using the BH and H or mPW1K functionals reproduce the experimental trends of the NQCC.

Sub-ppm Methane Detection with Mid-Infrared Slot Waveguides

Hybrid integration of photonic chips with electronic and micromechanical circuits is projected to bring about miniature, but still highly accurate and reliable, laser spectroscopic sensors for both climate research and industrial applications. However, the sensitivity of chip-scale devices has been limited by immature and lossy photonic waveguides, weak light-analyte interaction, and etalon effects from chip facets and defects. Addressing these challenges, we present a nanophotonic waveguide for methane detection at 3270.4 nm delivering a limit of detection of 0.3 ppm, over 2 orders of magnitude lower than the state-of-the-art of on-chip spectroscopy. We achieved this result with a Si slot waveguide designed to maximize the light-analyte interaction, while special double-tip fork couplers at waveguide facets suppress spurious etalon fringes. We also study and discuss the effect of adsorbed humidity on the performance of mid-infrared waveguides around 3 μm, which has been repeatedly overlooked in previous reports.

Cyclometalated (N,C) Au(III) Complexes: The Impact of Trans Effects on Their Synthesis, Structure, and Reactivity

ConspectusThe early years of gold catalysis were dominated by Au(I) complexes and inorganic Au(III) salts. Thanks to the development of chelating ligands, more sophisticated Au(III) complexes can now be easily prepared and handled. The choice of the ancillary ligand has great consequences for the synthesis, properties, and reactivity of the Au(III) complex in question. Among the major factors controlling reactivity are the "trans effect" and the "trans influence" that a ligand imparts at the ligand trans to itself. The kinetic trans effect manifests itself with an increased labilization of the ligand trans to a given ligand and arises from an interplay between ground-state and transition-state effects. The term trans influence, on the other hand, is a ground-state effect only, describing the tendency of a given ligand to weaken the metal-ligand bond trans to itself. Herein, we will use the term "trans effect" to describe both the kinetic and the thermodynamic properties, whereas the term "trans influence" will refer only to thermodynamic properties. We will describe how these trans effects strongly impact the chemistry of the commonly encountered cyclometalated (N,C) Au(III) complexes, a class of complexes we have studied for more than a decade. We found that the outcome of reactions like alkylation, arylation, and alkynylation as well as halide metathesis are dictated by the different trans influence of the two termini of the chelating tpy ligand in (tpy)Au(OAcF)2 (tpy = 2-(p-tolyl)pyridine, OAcF = OCOCF3, tpy-C > tpy-N). There is a strong preference for high trans influence ligands to end up trans to tpy-N, whereas the lower trans influence ligands end up trans to tpy-C. Taking advantage of these preferences, tailor-made (N,C)Au(III) complexes could be prepared. For the functionalization of alkenes at (tpy)Au(OAcF)2, the higher trans effect of tpy-C would suggest that the coordination site trans to tpy-C would be kinetically more available than the one trans to tpy-N. However, due to the thermodynamic preference of having the σ-bonded ligand, resulting from the nucleophilic addition to alkenes, trans to tpy-N, functionalization of alkenes was only observed trans to tpy-N. However, for a catalytic process, the reaction should happen trans to tpy-C, as was observed for the trifluoroacetoxylation of acetylene. When functionalizing acetylene in the coordination site trans to tpy-N, protolytic cleavage of the Au-C(vinyl) bond to release the product did not occur at all, whereas trans to tpy-C protolytic cleavage of the Au-C(vinyl) bond occurred readily, in agreement with the higher trans influence of tpy-C over tpy-N. The large impact of the trans effects in Au(III) complexes is finally exemplified with the synthesis of [(tpy)Au(π-allyl)]+[NTf2]-, which resulted in a highly asymmetric π + σ bonding of the allyl moiety. Here, the bonding is such that the most thermodynamically favorable situation is achieved, with the carbon trans to tpy-N bonded in a σ-fashion and the π-allyl double bond being coordinated trans to tpy-C.

Repurposing Azoles to Resolve Serotogenic Toxicity Associated with Linezolid to Combat Multidrug-Resistant Tuberculosis

Serotogenic toxicity is a major hurdle associated with Linezolid in the treatment of drug-resistant tuberculosis (TB) due to the inhibition of monoamine oxidase (MAO) enzymes. Azole compounds demonstrate structural similarities to the recognized anti-TB drug Linezolid, making them intriguing candidates for repurposing. Therefore, we have repurposed azoles (Posaconazole, Itraconazole, Miconazole, and Clotrimazole) for the treatment of drug-resistant TB with the anticipation of their selectivity in sparing the MAO enzyme. The results of repurposing revealed that Clotrimazole showed equipotent activity against the Mycobacterium tuberculosis (Mtb) H37Rv strain compared to Linezolid, with a minimal inhibitory concentration (MIC) of 2.26 μM. Additionally, Clotrimazole exhibited reasonable MIC50 values of 0.17 μM, 1.72 μM, 1.53 μM, and 5.07 μM against the inhA promoter+, katG+, rpoB+, and MDR clinical Mtb isolates, respectively, compared to Linezolid. Clotrimazole also exhibited 3.90-fold less inhibition of MAO-A and 50.35-fold less inhibition of MAO-B compared to Linezolid, suggesting a reduced serotonergic toxicity burden.

Triplet Excited States with Multilevel Coupled Cluster Theory

We extend the multilevel coupled cluster framework with triplet excitation energies at the singles and perturbative doubles (MLCC2) and singles and doubles (MLCCSD) levels of theory. In multilevel coupled cluster theory, we partition the orbitals and restrict the higher-order excitations in the cluster operator to a set of active orbitals. With an appropriate choice of these orbitals, the multilevel approach can give significant computational savings while maintaining the high accuracy of standard coupled cluster theory. In this work, we generated active orbitals from approximate correlated natural transition orbitals (CNTOs). The CNTOs form a compact orbital space specifically tailored to describe the triplet excited states of interest. We compare the performance of MLCCSD and MLCC2, in terms of cost and accuracy, to those of their standard coupled cluster counterparts (CC2 and CCSD) and finally show proof-of-concept calculations of the singlet-triplet gaps of molecules that are of interest for their potential use in organic light-emitting diodes.

The Structure of the Density-Potential Mapping. Part II: Including Magnetic Fields

The Hohenberg-Kohn theorem of density-functional theory (DFT) is broadly considered the conceptual basis for a full characterization of an electronic system in its ground state by just one-body particle density. In this Part II of a series of two articles, we aim at clarifying the status of this theorem within different extensions of DFT including magnetic fields. We will in particular discuss current-density-functional theory (CDFT) and review the different formulations known in the literature, including the conventional paramagnetic CDFT and some nonstandard alternatives. For the former, it is known that the Hohenberg-Kohn theorem is no longer valid due to counterexamples. Nonetheless, paramagnetic CDFT has the mathematical framework closest to standard DFT and, just like in standard DFT, nondifferentiability of the density functional can be mitigated through Moreau-Yosida regularization. Interesting insights can be drawn from both Maxwell-Schrödinger DFT and quantum-electrodynamic DFT, which are also discussed here.

Novel Calcium-Binding Motif Stabilizes and Increases the Activity of Aspergillus fumigatus Ecto-NADase

Nicotinamide adenine dinucleotide (NAD) is an essential molecule in all kingdoms of life, mediating energy metabolism and cellular signaling. Recently, a new class of highly active fungal surface NADases was discovered. The enzyme from the opportunistic human pathogen Aspergillus fumigatus was thoroughly characterized. It harbors a catalytic domain that resembles that of the tuberculosis necrotizing toxin from Mycobacterium tuberculosis, which efficiently cleaves NAD+ to nicotinamide and ADP-ribose, thereby depleting the dinucleotide pool. Of note, the A. fumigatus NADase has an additional Ca2+-binding motif at the C-terminus of the protein. Despite the presence of NADases in several fungal divisions, the Ca2+-binding motif is uniquely found in the Eurotiales order, which contains species that have immense health and economic impacts on humans. To identify the potential roles of the metal ion-binding site in catalysis or protein stability, we generated and characterized A. fumigatus NADase variants lacking the ability to bind calcium. X-ray crystallographic analyses revealed that the mutation causes a drastic and dynamic structural rearrangement of the homodimer, resulting in decreased thermal stability. Even though the calcium-binding site is at a long distance from the catalytic center, the structural reorganization upon the loss of calcium binding allosterically alters the active site, thereby negatively affecting NAD-glycohydrolase activity. Together, these findings reveal that this unique calcium-binding site affects the protein fold, stabilizing the dimeric structure, but also mediates long-range effects resulting in an increased catalytic rate.

Cost-Efficient High-Resolution Linear Absorption Spectra through Extrapolating the Dipole Moment from Real-Time Time-Dependent Electronic-Structure Theory

We present a novel function fitting method for approximating the propagation of the time-dependent electric dipole moment from real-time electronic structure calculations. Real-time calculations of the electronic absorption spectrum require discrete Fourier transforms of the electric dipole moment. The spectral resolution is determined by the total propagation time, i.e., the trajectory length of the dipole moment, causing a high computational cost. Our developed method uses function fitting on shorter trajectories of the dipole moment, achieving arbitrary spectral resolution through extrapolation. Numerical testing shows that the fitting method can reproduce high-resolution spectra by using short dipole trajectories. The method converges with as little as 100 a.u. dipole trajectories for some systems, though the difficulty converging increases with the spectral density. We also introduce an error estimate of the fit, reliably assessing its convergence and hence the quality of the approximated spectrum.

Coupled Cluster Simulation of Impulsive Stimulated X-ray Raman Scattering

Time-dependent equation-of-motion coupled cluster (TD-EOM-CC) is used to simulate impulsive stimulated X-ray Raman scattering (ISXRS) of ultrashort laser pulses by neon, carbon monoxide, pyrrole, and p-aminophenol. The TD-EOM-CC equations are expressed in the basis of field-free EOM-CC states, where the calculation of the core-excited states is simplified through the use of the core-valence separation (CVS) approximation. The transfer of electronic population from the ground state to the core- and valence-excited states is calculated for different numbers of included core- and valence-excited states, as well as for electric field pulses with different polarizations and carrier frequencies. The results indicate that Gaussian pulses can transfer significant electronic populations to the valence states through the Raman process. The sensitivity of this population transfer to the model parameters is analyzed. The time-dependent electronic density for p-aminophenol is also showcased, supporting the interpretation that ISXRS involves localized core excitations and can be used to rapidly generate valence wavepackets.

Electronic Properties of Zn2V(1-x)NbxN3 Alloys to Model Novel Materials for Light-Emitting Diodes

We propose the Zn2V(1-x)NbxN3 alloy as a new promising material for optoelectronic applications, in particular for light-emitting diodes (LEDs). We perform accurate electronic-structure calculations of the alloy for several concentrations x using density-functional theory with meta-GGA exchange-correlation functional TB09. The band gap is found to vary between 2.2 and 2.9 eV with varying V/Nb concentration. This range is suitable for developing bright LEDs with tunable band gap as potential replacements for the more expensive Ga(1-x)In(x)N systems. Effects of configurational disorder are taken into account by explicitly considering all possible distributions of the metal ions within the metal sublattice for the chosen supercells. We have evaluated the band gap's nonlinear behavior (bowing) with variation of V/Nb concentration for two possible scenarios: (i) only the structure with the lowest total energy is present at each concentration and (ii) the structure with minimum band gap is present at each concentration, which corresponds to experimental conditions when also metastable structures are presents. We found that the bowing is about twice larger in the latter case. However, in both cases, the bowing parameter is found to be lower than 1 eV, which is about twice smaller than that in the widely used Ga(1-x)In(x)N alloy. Furthermore, we found that both crystal volume changes due to alloying and local effects (atomic relaxation and the V-N/Nb-N bonding difference) have important contributions to the band gap bowing in Zn2V(1-x)NbxN3.

Molecular van der Waals Fluids in Cavity Quantum Electrodynamics

Intermolecular van der Waals interactions are central to chemical and physical phenomena ranging from biomolecule binding to soft-matter phase transitions. In this work, we demonstrate that strong light-matter coupling can be used to control the thermodynamic properties of many-molecule systems. Our analyses reveal orientation dependent single molecule energies and interaction energies for van der Waals molecules. For example, we find intermolecular interactions that depend on the distance between the molecules R as R-3 and R0. Moreover, we employ ab initio cavity quantum electrodynamics calculations to develop machine-learning-based interaction potentials for molecules inside optical cavities. By simulating systems ranging from 12 H2 to 144 H2 molecules, we observe varying degrees of orientational order because of cavity-modified interactions, and we explain how quantum nuclear effects, light-matter coupling strengths, number of cavity modes, molecular anisotropies, and system size all impact the extent of orientational order.

Low-Cost Particulate Matter Sensors for Monitoring Residential Wood Burning

Conventional monitoring systems for air quality, such as reference stations, provide reliable pollution data in urban settings but only at relatively low spatial density. This study explores the potential of low-cost sensor systems (LCSs) deployed at homes of residents to enhance the monitoring of urban air pollution caused by residential wood burning. We established a network of 28 Airly (Airly-GSM-1, SP. Z o.o., Poland) LCSs in Kristiansand, Norway, over two winters (2021-2022). To assess performance, a gravimetric Kleinfiltergerät measured the fine particle mass concentration (PM2.5) in the garden of one participant's house for 4 weeks. Results showed a sensor-to-reference correlation equal to 0.86 for raw PM2.5 measurements at daily resolution (bias/RMSE: 9.45/11.65 μg m-3). High-resolution air quality maps at a 100 m resolution were produced by combining the output of an air quality model (uEMEP) using data assimilation techniques with the network data that were corrected and calibrated by using a proposed five-step network data processing scheme. Leave-one-out cross-validation demonstrated that data assimilation reduced the model's RMSE, MAE, and bias by 44-56, 38-48, and 41-52%, respectively.

Systematic Study of Wettability Alteration of Glass Surfaces by Dichlorooctamethyltetrasiloxane Silanization-A Guide for Contact Angle Modification

To investigate the effects of wettability on multiphase flow in porous media, glass bead packs or micromodels are commonly used. Their wettability can be altered by the surface treatment method-silanization. Although silanization is widely used for glass wettability modification, comparable systematic approaches over a large range of geometries, treatment conditions, and measurement systems are scarce. In this work, dichlorooctamethyltetrasiloxane (Surfasil) treatment was systematically investigated, resulting in a guide for achieving a wide range of contact angles. Initially, the influence of the Surfasil solvent, treatment time, and Surfasil-to-solvent ratio was investigated on glass plates using the sessile drop method. By varying these variables, it was possible to achieve a wide range of comparable, repeatable, and stable contact angles, from approximately 20-95° for air-water systems. Due to the linear increase of contact angle with larger Surfasil exposure, either due to the time or concentration, contact angle tuning is possible until the critical point. Beyond the critical point of exposure, a system-specific plateau value is reached, independent of the approach. After establishing a clear relationship between the parameters and contact angles, the same treatment parameters were applied to single beads, micromodels, and beadpacks with heptane as the chosen solvent. Optical image analysis was used for the microchips, and micro CT data analysis was used for the bead packs. The treatment appeared to be transferable to all geometries, resulting in similar wetting conditions within the limitations of the measurements. It is concluded that a glass plate can be used as an analogue for obtaining the contact angle alteration trends for more complex porous media with similar compositions. Data analysis methods and surface roughness could have an effect on the obtained contact angle spread.

Synergistic Gas Hydrate and Corrosion Inhibition Using Maleic Anhydride: N-Isopropylmethacrylamide Copolymer and Small Thiols

Kinetic gas hydrate inhibitors (KHIs) are often used in combination with film-forming corrosion inhibitors (CIs) in oilfield production flow lines. However, CIs can be antagonistic to KHI performance. In this study, maleic anhydride-co-N-isopropylmethacrylamide copolymer (MA:NIPMAM) and its derivatives were successfully synthesized and tested for gas hydrate and corrosion inhibition. KHI slow constant cooling (1 °C/h) screening tests in high-pressure rocking cells with synthetic natural gas and CO2 corrosion bubble tests in brine were performed in this study. The results revealed that underivatized MA:NIPMAM in water (as maleic acid:NIPMAM copolymer) showed poor KHI performance, probably due to internal hydrogen bonding. However, derivatization of MA:NIPMAM with 3-(dibutylamino)-1-propylamine (DBAPA) to give MA:NIPMAM-DBAPA gave excellent gas hydrate inhibition performance but only weak corrosion inhibition performance. Unlike some KHI polymers, MA:NIPMAM-DBAPA was compatible with a classic fatty acid imidazoline CI, such that neither the KHI polymer performance nor the corrosion inhibition of the imidazoline was affected. Furthermore, excellent dual gas hydrate and corrosion inhibition was also achieved in blends of MA:NIPMAM-DBAPA with small thiol-based molecules. In particular, the addition of butyl thioglycolate not only gave excellent corrosion inhibition efficiency, better than adding the fatty imidazoline, but also enhanced the overall gas hydrate inhibition performance.

Retention Time and Fragmentation Predictors Increase Confidence in Identification of Common Variant Peptides

Precision medicine focuses on adapting care to the individual profile of patients, for example, accounting for their unique genetic makeup. Being able to account for the effect of genetic variation on the proteome holds great promise toward this goal. However, identifying the protein products of genetic variation using mass spectrometry has proven very challenging. Here we show that the identification of variant peptides can be improved by the integration of retention time and fragmentation predictors into a unified proteogenomic pipeline. By combining these intrinsic peptide characteristics using the search-engine post-processor Percolator, we demonstrate improved discrimination power between correct and incorrect peptide-spectrum matches. Our results demonstrate that the drop in performance that is induced when expanding a protein sequence database can be compensated, hence enabling efficient identification of genetic variation products in proteomics data. We anticipate that this enhancement of proteogenomic pipelines can provide a more refined picture of the unique proteome of patients and thereby contribute to improving patient care.

Influence of Fluorinated Substituents on the Near-Infrared Phosphorescence of 5d Metallocorroles

The influence of fluorinated substituents on the luminescent properties of rhenium-oxo, osmium-nitrido, and gold triarylcorroles was studied via a comparison of four ligands: triphenylcorrole (TPC), tris(p-trifluoromethylphenyl)corrole (TpCF3PC), tris{3,5-bis(trifluoromethyl)phenyl}corrole (T3,5-CF3PC), and tris(pentafluorophenyl)corrole (TPFPC). For each metal series examined, fluorinated substituents were found to enhance the luminescent properties, with the phosphorescence quantum yields and triplet decay times increasing in the order TPC < TpCF3PC < T3,5-CF3PC < TPFPC. Among the 11 complexes examined, the highest phosphorescence quantum yield, 2.2%, was recorded for Re[TPFPC](O).

Free-Base Corrole Anion

Free-base corroles have long been known to be acidic, readily undergoing deprotonation by mild bases and in polar solvents. The conjugate base, however, has not been structurally characterized until now. Presented here is a first crystal structure of a free-base corrole anion, derived from tris(p-cyanophenyl)corrole, as the tetrabuylammonium salt. The low-temperature (100 K) structure reveals localized hydrogens on a pair of opposite pyrrole nitrogens. DFT calculations identify such a structure as the global minimum but also point to two cis tautomers only 4-7 kcal/mol above the ground state. In terms of free energy, however, the cis tautomers are above or essentially flush with the trans-to-cis barrier so the cis tautomers are unlikely to exist or be observed as true intermediates. Thus, the hydrogen bond within each dipyrrin unit on either side of the molecular pseudo-C2 axis through C10 (i.e., between pyrrole rings A and B or between C and D) qualifies as or closely approaches a low-barrier hydrogen bond. Proton migration across the pseudo-C2 axis entails much higher activation energies >20 kcal/mol, reflecting the relative rigidity of the molecule along the C1-C19 pyrrole-pyrrole linkage.

The Role of Chloride ion in the Silicate Condensation Reaction from ab Initio Molecular Dynamics Simulations

The comprehension of silicate oligomer formation during the initial stage of zeolite synthesis is of significant importance. In this study, we investigated the effect of chloride ions (Cl-) on silicate oligomerization using ab initio molecular dynamics simulations with explicit water molecules. The results show that the presence of Cl- increases the free energy barriers of all reactions compared to the case without the anion. The formation of the 4-ring structure has the lowest free energy barrier (73 kJ/mol), while the formation of the 3-ring structure has the highest barrier (98 kJ/mol) in the presence of Cl-. These findings suggest that Cl- suppresses the formation of 3-rings and favors the formation of larger oligomers in the process of zeolite synthesis. Our study provides important insights into the directing role of Cl- in silicate oligomerization by regulating thermodynamic and kinetic parameters. An important point to consider is the impact of the anion on aqueous reactions, particularly in altering the hydrogen bond network around reactive species. These results also provide a basis for further studies of the formations of larger silicate oligomers in solution.

Oxidation Kinetics of Nanocrystalline Hexagonal RMn1-xTixO3 (R = Ho, Dy)

Hexagonal manganites, RMnO3 (R = Sc, Y, Ho-Lu), are potential oxygen storage materials for air separation due to their reversible oxygen storage and release properties. Their outstanding ability to absorb and release oxygen at relatively low temperatures of 250-400 °C holds promise of saving energy compared to current industrial methods. Unfortunately, the low temperature of operation also implies slow kinetics of oxygen exchange in these materials, which would make them inefficient in applications such as chemical looping air separation. Here, we show that the oxidation kinetics of RMnO3 can be improved through Ti4+-doping as well as by increasing the rare earth cation size. The rate of oxygen absorption of nanocrystalline RMn1-xTixO3 (R = Ho, Dy; x = 0, 0.15) was investigated by thermogravimetric analysis, X-ray absorption near-edge structure, and high-temperature X-ray diffraction (HT-XRD) with in situ switching of atmosphere from N2 to O2. The kinetics of oxidation increases for larger R and even more with Ti4+ donor doping, as both induce expansion of the ab-plane, which reduces the electrostatic repulsion between oxygen in the lattice upon oxygen ion migration. Surface exchange rates and activation energies of oxidation were determined from changes in lattice parameters observed through HT-XRD upon in situ switching of atmosphere.

The Transition from Unfolded to Folded G-Quadruplex DNA Analyzed and Interpreted by Two-Dimensional Infrared Spectroscopy

A class of DNA folds/structures known collectively as G-quadruplexes (G4) commonly forms in guanine-rich areas of genomes. G4-DNA is thought to have a functional role in the regulation of gene transcription and telomerase-mediated telomere maintenance and, therefore, is a target for drugs. The details of the molecular interactions that cause stacking of the guanine-tetrads are not well-understood, which limits a rational approach to the drugability of G4 sequences. To explore these interactions, we employed electron-vibration-vibration two-dimensional infrared (EVV 2DIR) spectroscopy to measure extended vibrational coupling spectra for a parallel-stranded G4-DNA formed by the Myc2345 nucleotide sequence. We also tracked the structural changes associated with G4-folding as a function of K+-ion concentration. To classify the structural elements that the folding process generates in terms of vibrational coupling characteristics, we used quantum-chemical calculations utilizing density functional theory to predict the coupling spectra associated with given structures, which are compared against the experimental data. Overall, 102 coupling peaks are experimentally identified and followed during the folding process. Several phenomena are noted and associated with formation of the folded form. This includes frequency shifting, changes in cross-peak intensity, and the appearance of new coupling peaks. We used these observations to propose a folding sequence for this particular type of G4 under our experimental conditions. Overall, the combination of experimental 2DIR data and DFT calculations suggests that guanine-quartets may already be present before the addition of K+-ions, but that these quartets are unstacked until K+-ions are added, at which point the full G4 structure is formed.

Cleaning Up without Messing Up: Maximizing the Benefits of Plastic Clean-Up Technologies through New Regulatory Approaches

As the global plastics crisis grows, numerous technologies have been invented and implemented to recover plastic pollution from the environment. Although laudable, unregulated clean-up technologies may be inefficient and have unintended negative consequences on ecosystems, for example, through bycatch or removal of organic matter important for ecosystem functions. Despite these concerns, plastic clean-up technologies can play an important role in reducing litter in the environment. As the United Nations Environment Assembly is moving toward an international, legally binding treaty to address plastic pollution by 2024, the implementation of plastic clean-up technologies should be regulated to secure their net benefits and avoid unintended damages. Regulation can require environmental impact assessments and life cycle analysis to be conducted predeployment on a case-by-case basis to determine their effectiveness and impact and secure environmentally sound management. During operations catch-efficiency and bycatch of nonlitter items, as well as waste management of recovered litter, should be documented. Data collection for monitoring, research, and outreach to mitigate plastic pollution is recommended as added value of implementation of clean-up technologies.

Probing Catalyst Degradation in Metathesis of Internal Olefins: Expanding Access to Amine-Tagged ROMP Polymers

Ruthenium-promoted ring-opening metathesis polymerization (ROMP) offers potentially powerful routes to amine-functionalized polymers with antimicrobial, adhesive, and self-healing properties. However, amines readily degrade the methylidene and unsubstituted ruthenacyclobutane intermediates formed in metathesis of terminal olefins. Examined herein is the relevance of these decomposition pathways to ROMP (i.e., metathesis of internal olefins) by the third-generation Grubbs catalyst. Primary alkylamines rapidly quench polymerization via fast adduct formation, followed by nucleophilic abstraction of the propagating alkylidene. Bulkier, Brønsted-basic amines are less aggressive: attack competes only for slow polymerization or strong bases (e.g., DBU). Added HCl limits degradation, as demonstrated by the successful ROMP of an otherwise intractable methylamine monomer.

SANS Spectra with PLUMED: Implementation and Application to Metainference

Using small-angle scattering with either X-ray or neutron sources has become common in the investigation of soft-matter systems. These experiments provide information about the coarse shape of the scattered objects, but obtaining more-detailed information can usually only be achieved with the aid of molecular simulations. In this Application Note, we report the implementation of an extension in PLUMED to compute the small-angle neutron scattering (SANS), which can be used for data processing as well for enhanced sampling, in particular with the metainference method to bias simulations and sample structures with a resulting spectrum in agreement with an experimental reference. Our implementation includes a resolution function that can be used to smear the SANS intensities according to beamline error sources and is compatible with both all-atom and coarse-grained simulations. Scripts to aid in the calculation of the scattering lengths when the system is coarse-grained and to aid in preparing the inputs are provided. We illustrate the use of the implementation with metainference by performing coarse-grained simulations of beta-octylglucoside and dodecylphosphocholine micelles in water. With different software and different Hamiltonians, we show that the metainference SANS bias can drive micelles to be split and to change shapes to achieve a better agreement with the experimental reference.

Design, Synthesis, and Evaluation of Novel Δ2-Thiazolino 2-Pyridone Derivatives That Potentiate Isoniazid Activity in an Isoniazid-Resistant Mycobacterium tuberculosis Mutant

Mycobacterium tuberculosis (Mtb) drug resistance poses an alarming threat to global tuberculosis control. We previously reported that C10, a ring-fused thiazolo-2-pyridone, inhibits Mtb respiration, blocks biofilm formation, and restores the activity of the antibiotic isoniazid (INH) in INH-resistant Mtb isolates. This discovery revealed a new strategy to address INH resistance. Expanding upon this strategy, we identified C10 analogues with improved potency and drug-like properties. By exploring three heterocycle spacers (oxadiazole, 1,2,3-triazole, and isoxazole) on the ring-fused thiazolo-2-pyridone scaffold, we identified two novel isoxazoles, 17h and 17j. 17h and 17j inhibited Mtb respiration and biofilm formation more potently with a broader therapeutic window, were better potentiators of INH-mediated inhibition of an INH-resistant Mtb mutant, and more effectively inhibited intracellular Mtb replication than C10. The (-)17j enantiomer showed further enhanced activity compared to its enantiomer and the 17j racemic mixture. Our potent second-generation C10 analogues offer promise for therapeutic development against drug-resistant Mtb.