Electrostatic Analysis Research Articles

C···S Tetrel Bond Favored in the Phenyl Isothiocyanate-CO2 Complex: A Rotational Study.

The rotational spectrum of the phenyl isothiocyanate-CO2 complex was investigated by pulsed-jet Fourier transform microwave spectroscopy complemented by quantum chemical calculations. Only one isomer, with CO2 almost in the plane of phenyl isothiocyanate, has been detected in the pulsed jet, of which the spectrum displays a quadrupole coupling hyperfine structure due to the presence of a 14N nucleus (I = 1). This structure is nearly equal to the lowest energy geometry obtained by B3LYP-D3(BJ)/6-311++G(d,p), which has been dominated by a C···S tetrel bond (n → π* interaction) and one secondary C-H···O hydrogen bond (n → σ* interaction). Molecular electrostatic potential and natural bond orbital analysis were used to characterize the noncovalent interactions of the complex. The results from this study would lay the groundwork for the design and advancement of materials that exhibit high efficiency in capturing CO2.

Chitosan-alginate sponge with multiple cross-linking networks for adsorption of anionic dyes: Preparation, property evaluation, mechanism exploration, and application

A chitosan-alginate sponge (CAS) with multiple cross-linking networks was developed using chitosan, sodium alginate, polyvinyl alcohol, and glutaraldehyde to adsorb and enrich the anionic dyes form the food samples. The multiple networks in CAS refer to the electrostatic cross-linking network, hydrogen bonding cross-linking network, and covalent cross-linking network. Compared with pure chitosan and alginate sponges, the CAS showed better three-dimensional network structure, mechanical behavior, and stability, which is benefit by multiple cross-linking networks. The physical and chemical properties of CAS were systematically studied by a series of characterizations. The adsorption performance of CAS on anionic dyes was inspected with different dye concentration, time, temperature, and pH conditions. CAS exhibited a good and stable adsorption property to amaranth, carmine, and sunset yellow with the saturation adsorption capacity of 94.34, 111.5, and 80.05 mg∙g–1, respectively. Furthermore, CAS performed outstanding selectivity to anionic dyes with the selectivity factor up to 16.99. Through electrostatic potential analysis, it is inferred that CAS mainly adsorbs anionic dyes through electrostatic interactions. CAS showed satisfactory reusability, maintaining 97 %–99 % of adsorption performance after six cycles of recycling. Finally, CAS was combined with high-performance liquid chromatography for the enrichment and detection of anionic dyes in candy and cocktail samples, achieving the enrichment factor up to 84.77.

Unraveling pnicogen bonding cooperativity: Insights from molecular electrostatic potential analysis.

A theoretical investigation on the cooperativity of a series of binary, ternary, and quaternary complexes interconnected by pnicogen bonds has been conducted using calculations at the M06-2X/aug-cc-pVTZ level of density functional theory. By measuring changes in the molecular electrostatic potential (MESP) at the nucleus of interacting atoms in all of the complexes, it is possible to quantify the substantial reorganization of the electron density triggered by the formation of pnicogen bonds. The positive change in MESP, indicating a loss of electron density from the donor molecule in a dimer, facilitates the acceptance of electron density from a third molecule, resulting in the formation of a ternary complex with a stronger pnicogen bond compared to the one present in the binary complex. Similarly, the acceptor molecule in a dimer with a negative change in MESP showed an enhanced tendency to donate electron density to an electron-deficient third molecule. The MESP analysis provided valuable insights into the donor/acceptor characteristics of pnicogen bonds within the quaternary complexes. The proposed MESP hypotheses are consistent with the positive cooperativity observed in the pnicogen-bonded clusters. To quantify the changes in MESP, both at the donor atom (ΔVdonor ) and the acceptor atom (ΔVacceptor ), for all pnicogen bonds in the cluster, the total change in MESP (ΔΔVn ) was measured as ΔΔVn = ∑(ΔVdonor )-∑(ΔVacceptor ). Remarkably, ΔΔVn exhibited a strong linear relationship with the sum of the bond energies of the pnicogen bonds in the cluster. This establishes the MESP analysis as a robust approach for understanding the strength and cooperative behavior of pnicogen-bonded clusters. Additionally, the MESP features provided clear evidence of pnicogen bond formation, further supporting the reliability of this approach.

Cloning, computational analysis and expression profiling of steroid 5 alpha-reductase 1 (SRD5A1) gene during reproductive phases and ovatide stimulation in endangered catfish, Clarias magur

The cloning and characterization of the complete coding sequence of the Clarias magur SRD5A1 (CmSRD5A1) gene, which encodes an enzyme responsible for regulating steroid levels by converting testosterone into 5α-dihydrotestosterone (DHT), have been successfully achieved. DHT plays a vital role in enabling the complete expression of testosterone's actions in neuroendocrine tissues. The ORF of the full-length cDNA sequence of SRD5A1 was 795 bp, translating into 265 amino acids, with a total length of 836 bp including UTRs. Like other vertebrates, the signal peptide analysis revealed that SRD5A1 is a non-secretory protein, and hydropathy profiles indicated that it is hydrophobic in nature. The 3D structure of CmSRD5A1 sequence generated above was predicted using highly accurate AlphaFold 2 in Google Colab online platform. CmSRD5A1 contains seven transmembrane helices connected by six loops, with the N-termini located on the periplasmic side and C-termini on the cytosolic side. Structural superimposition with known bacterial and human SRD5As showed very high structural similarity. The electrostatic potential calculation and surface analysis of CmSRD5A1 revealed the presence of a large cavity with two openings one highly electropositive towards the cytosolic side and another relatively neutral towards the transmembrane region. The structural comparison revealed that the electropositive side of the cavity should bind to NADPH and the steroid hormone in the hydrophobic environment. Polar residues binding to NADPH are highly conserved and the same as known strictures. The conserved residues involved in hydrogen bonding with the ketone group at C-3 in the steroids hence fevering Δ4 double-bond reduction are identified as E66 and Y101. Our findings showed that SRD5A1 expression was lower during the spawning phase than the preparatory phase in female fish, while the administration of Ovatide (a GnRH analogue) resulted in up-regulation of expression after 6 h of injection in the ovary. In males, the lowest expression was observed during the preparatory phase and peaked at 16 h post- Ovatide injection in the testis. The expression of SRD5A1 in the brain of female fish was slightly higher during the Ovatide stimulation phase than the spawning phase. This study represents the first report on the cloning and characterization of the full-length cDNA of SRD5A1 in Indian catfish.

Novel Stator Slot Opening to Reduce Electrical Machine Bearing Currents

Ball bearings are largely used in electrical machines, where the high frequency common mode currents affect their lifetime. This document presents a novel Zig-Zag stator slot opening geometry to reduce the winding-to-rotor capacitance <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C_wr</i> with the consequent reduction of Bearing Voltage Ratio and electrical discharge machining bearing currents. An improved analytical model to permit the calculation of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C_wr</i> for unusual slot opening geometries is implemented. Electrostatic and electromagnetic Finite Element Analysis comparisons between the Zig-Zag, oblique and original (classical slot opening configuration) machines are performed. These comparisons suggest that the Zig-Zag model presents the best performance in terms of Bearing Voltage Ratio reduction, while keeping torque performance close to the original machine. An additional comparison between the novel Zig-Zag model and the classical one with reduced slot opening to have the same <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C_wr</i> values is proposed, showing an higher degradation in terms of torque performance for the latter. The study shows that the Zig-Zag model could be a good candidate to reduce effectively electrical machine bearing currents. A validation test is proposed on two motorette prototypes having classical and Zig-Zag slot opening configurations, respectively. Moreover, the improved analytical method can be helpful for engineers and researchers to calculate <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C_wr</i> with a good accuracy for unusual slot opening geometries.

Crystal structures of QseE and QseG: elements of a three-component system from Escherichia coli.

Bacteria regulate virulence by using two-component systems (TCSs) composed of a histidine kinase (HK) and a response regulator (RR). TCSs respond to environmental signals and change gene-expression levels. The HK QseE and the RR QseF regulate the virulence of Enterobacteriaceae bacteria such as enterohemorrhagic Escherichia coli. The operon encoding QseE/QseF also contains a gene encoding an outer membrane lipoprotein, qseG. The protein product QseG interacts with QseE in the periplasmic space to control the activity of QseE and constitutes a unique QseE/F/G three-component system. However, the structural bases of their functions are unknown. Here, crystal structures of the periplasmic regions of QseE and QseG were determined with the help of AlphaFold models. The periplasmic region of QseE has a helix-bundle structure as found in some HKs. The QseG structure is composed of an N-terminal globular domain and a long C-terminal helix forming a coiled-coil-like structure that contributes to dimerization. Comparison of QseG structures obtained from several crystallization conditions shows that QseG has structural polymorphisms at the C-terminus of the coiled-coil structure, indicating that the C-terminus is flexible. The C-terminal flexibility is derived from conserved hydrophilic residues that reduce the hydrophobic interaction at the coiled-coil interface. Electrostatic surface analysis suggests that the C-terminal coiled-coil region can interact with QseE. The observed structural fluctuation of the C-terminus of QseG is probably important for interaction with QseE.

In-Silico Aided Screening and Characterization Results in Stability Enhanced Novel Roxadustat Co-Crystal

Roxadustat (RXD) is an approved drug substances for the treatment of renal anemia. It has poor aqueous solubility and photochemical stability. This study employs a comprehensive approach to enhance the stability and physicochemical properties RXD through coformer selection and characterization. The investigation integrates delta pKa analysis, molecular complementary assessment, molecular electrostatic potential surface analysis, and machine learning techniques to predict potential co-crystal formation and binding interactions between drug molecules and coformers. The co-crystal screening which lead to in a novel RXD-nicotinamide co-crystal (RXD-NA). Experimental characterization underscores the physical and chemical stability of the co-crystals. To elucidate the supramolecular synthons and understand the intermolecular interactions in the RXD-NA co-crystal, Hirshfeld surfaces analysis, quantum theory of atoms in molecules (QTAIM) analysis and non-covalent interaction (NCI) analysis were performed. Computational analysis of photo-isomer formation aligns with experimental observations, further enhancing our understanding of RXD-coformer interactions. RXD-NA co-crystal was found photo-chemically stable as compared to free base API drug substance. This integrated methodology provides a systematic framework for informed co-crystal design, holding promise for optimizing RXD formulations based on molecular interactions and stability considerations. Consequently, this study contributes valuable insights to the field of rational drug design and formulation optimization.

Quantum computations of non-steroidal anti-inflammatory drug molecules using Density Functional Theory

This paper addresses the electronic states and physicochemical properties of non-steroidal anti-inflammatory drug (NSAID) namely: Ibuprofen, Ketoprofen and Flufenamic acid. The molecular structures are quantum chemically treated and geometrically optimised using density functional theory (DFT). The computed geometrical parameters are compared with the experimental data. The Mulliken charge analysis is accomplished to understand the partial charge distribution in molecules. The molecular electrostatic potential analysis has been used to identify the appropriate location for an electrophilic and nucleophilic attacking site. Frontier molecular orbitals of the molecules are estimated and analysed. The HOMO-LUMO energy gaps have been used to estimate the different global reactivity descriptors of the selected molecules under investigation. The FT-IR spectra of molecules are recorded experimentally and are computed using DFT. The potential energy distribution (PED) assignment for the computed vibrations is carried out. The NBO analysis has been used to find the most intensive interaction in molecules based on the Fock-matrix sta3bilization energy. The NLO parameters have been computed for molecules to check their suitability towards NLO based applications. The UV-absorption spectra and ADME parameters for titled molecules are also simulated.

A pilot scale test study with theoretical justification of reaction mechanism for the recovery of chromium(VI) based on solvent extraction using novel centrifugal extractors

As a strategic resource and hazardous substance, the purification and recovery of chromium(VI) from the aqueous phase have attracted attention. In this study, the centrifugal extractor was used to treat the leach liquor of sodium roasting chromite on a pilot scale. The extraction performance and equilibrium distribution of chromium in countercurrent extraction were investigated. Meanwhile, the scrubbing effect of impurities was carefully studied, and the stripping and regeneration effects of the organic phase were tested. Under the selected process parameters, the pilot scale test results, including extraction efficiency of chromium, scrubbing efficiency of impurities, and regeneration performance of the organic phase, were excellent. The qualified (NH4)2Cr2O7 and Cr2O3 products were prepared using the strip liquor, and several physical properties of the products were tested. In addition, the molecular electrostatic potential surface maps, HOMO-LUMO orbitals, Fukui functions, and single point energy of the molecules involved were calculated by Quantum Chemistry. The molecular electrostatic potential analysis, frontiers molecular orbital analysis, Fukui function analysis and interaction energy analysis were applied to investigate the mechanism of separation of chromic acid from impurities in the extraction system.

Microwave-assisted solvent-free synthesis, Hirshfeld surface analysis and DFT studies of 1-(hydroxymethyl)-pyrazoles

A facile high-yield, solvent-free approach for the synthesis of a series of 1-(hydroxymethyl)-pyrazoles under microwave irradiation was developed for the first time. The structures of four pyrazoles compounds were characterised by a single-crystal X-ray diffraction, and showed interesting intermolecular O‒H∙∙∙N hydrogen bonding linking two pyrazoles molecules to form R22(10) dimer architectures. In additional, the intermolecular interactions in the crystal were investigated through the Hirshfeld surface analysis to understand the characteristics of the close contacts, and the 2D-fingerprint plot data exposed that a significant contributions to the crystal packing are from N∙∙∙H/H∙∙∙N contacts. The geometry optimization, electronic properties and energies level of HOMO, LUMO were performed by Density functional theory (DFT) calculations. Quantitative electrostatic potential analysis (ESP) and independent gradient model based on Hirshfeld partition (IGMH) explained the active hydrogen bonding sites in four pyrazoles compounds and confirmed the hydrogen bonding modes in their crystal structure.

Molecularly imprinted polymer based on magnetic porous cellulose for specific adsorption of tetracyclines: Preparation, characterization, property evaluation, and application

A magnetic porous cellulose molecularly imprinted polymer (MPCMIP) based on tetracyclines was prepared with Fe3O4 as the magnetic core and porous cellulose as the carrier. The appearance, characteristic chemical bonds, crystal structure, thermal stability, and magnetism of MPCMIP were systematically characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and vibrating sample magnetometry. The adsorption performance of MPCMIP to tetracycline, demeclocycline, and minocycline were comprehensively investigated by static adsorption, dynamic adsorption, and adsorption experiments under different temperature and pH conditions. MPCMIP performed good adsorption performance and fast adsorption rate for tetracyclines, and adsorption quantity and efficiency of MPCMIP were four times and twice that of traditional molecularly imprinted polymer (MIP), respectively. It can be seen that the introduction of magnetic porous cellulose effectively improved the adsorption performance of the MIP. Moreover, MPCMIP showed good adsorption stability under different temperature. The adsorption properties of MPCMIP under neutral and alkaline conditions were better than those under acidic conditions. Selective experiment was conducted with the amoxicillin and levofloxacin as the coexisting interfering compounds for the three tetracyclines. The results showed that MPCMIP possessed good imprinting effect with the impact factor values for tetracycline, demeclocycline, and minocycline of 1.49, 1.66, and 3.14, respectively. Compared with interfering compounds, MPCMIP showed excellent selectivity to tetracyclines with the selectivity factor up to 36.9. Moreover, MPCMIP exhibited better selectivity towards tetracyclines than traditional MIP according to the higher imprinting and selectivity factors of MPCMIP. The simulation of hydrogen bonding interaction and electrostatic potential analysis determined that MPCMIP mainly adsorbed TCs through the hydrogen bonding and electrostatic interactions. The results of adsorption/desorption cycling experiments indicated that MPCMIP had good reusability with 95.5% of adsorption performance after four cycles. Finally, MPCMIP combined with high-performance liquid chromatography were triumphantly used to adsorb and detect the tetracycline, demeclocycline, and minocycline in river, beef, and milk samples. Furthermore, the MPCMIP method exhibited higher sensitivity, accuracy, and selectivity than the traditional method.

Sulfur Centered Hydrogen Bonding in Thioglycolic Acid and Its Clusters: A Computational Exploration.

The conformational landscape of thioglycolic acid (TGA) was investigated by using the CCSD/cc-pVTZ level of theory. The GGC conformer was identified as the global minimum, followed by the GAC conformer. The calculated rotational constant for the GGC conformer exhibited good agreement with the previously reported experimental results. Subsequently, the study delved into the exploration of sulfur-centered hydrogen bonding in TGA's dimer and trimer clusters, employing the CCSD/cc-pVDZ level of theory. These clusters revealed the participation of both oxygen and sulfur atoms in noncovalent H-bonding, contributing to their stability. The presence of these noncovalent interactions in TGA clusters was elucidated through Atoms in Molecule (AIM), reduced density gradient (RDG), and natural bond order (NBO) analysis, while electrostatic potential (ESP) charge and vibrational mode analysis further supported these findings.

Investigational, computational explorations on betanin, lycopene, cyanidin, and peonidin organic photo sensitizers for green energy harvesting

In keeping green energy harvesting as a prime priority and lowering the cost per watt, three potential red-colored organic photosensitizers were separated and employed for proficient titanium dioxide (TiO2) photoanodes. In a prime attempt, Rivina Humilis fruit extract (Betanin) was used for natural dye-sensitized solar cells (NDSSCs). The Prunus cerasus fruits and Solanum lycopersicum fruits (Lycopene) extracts were also successfully employed to fabricate NDSSCs. Cyanidin, Peonidin, and Lycopene are the prominent colorants existent in Prunus cerasus, and their optimized molecular structure was premeditated via Density functional theory. Their thermochemistry and associated physical parameters, Frontier molecular orbitals (FMOs) analyses, theoretical ultraviolet (UV) – visible exploration, and molecular electrostatic potential reactivity analysis were studied. Microwave-assisted sol–gel practice has yielded pure anatase TiO2 nanoparticles (NPs). The pure, red dye-sensitized TiO2 NPs endured needed studies. Environment-friendly, cost-per-watt effective NDSSCs were accomplished by expanding three red-colored organic photoanodes. Among three photosensitizers, Rivina Humilis fruits showed 1.35%, followed by Prunus cerasus at 1.27 % and slightest by Solanum lycopersicum at 0.82%. And, owing to the above performances, these NDSSCs have the potential to be employed in low-power indoor energy harvesting.

Effect of resolution enhancement using metal ion assisted strategy based on electrospray ionization-ion mobility spectrometry: A case study of carbendazim and thiabendazole in fruits

A method for the rapid and simultaneous determination of carbendazim and thiabendazole residues by electrospray ionization-ion mobility spectrometry (ESI-IMS) combined with a metal ion-assisted technique was developed and validated in different fruit matrices. The metal ion assisted strategy was performed instead of tedious pre-separation procedures to overcome the limitation of low resolution of IMS. Four transition metal cations, Co(II), Ni(II), Cu(II), and Zn(II), were screened and their interactions with carbendazim and thiabendazole were investigated. The injection flow rate and metal ion concentration were optimized. The Cu(II) assisted approach helped to achieve well-separated peaks with a peak-to-peak resolution of 3.61. This method was then applied to detect carbendazim and thiabendazole simultaneously in apples, pears, bananas, and mangoes. The limit of detection (LOD) were 0.03 mg kg−1 and 0.13 mg kg−1 for carbendazim and thiabendazole, respectively, while spiked recoveries were 61.5–122.0% and 83.5–119.8%, respectively, with RSDs less than 13.9%. These satisfactory evaluation parameters indicated that the approach was capable of performing quantitative analysis of multi-pesticide residues. In addition, the feasibility of using metal ion assisted-ESI-IMS for the simultaneous detection also was theoretically demonstrated through molecular electrostatic potential analysis and binding energy calculation based on density functional theory (DFT). Both experimental and theoretical results revealed the effectiveness of the metal ion assisted strategy in improving the resolution of ESI-IMS.

Ag‐based bimetallic clusters as catalysts for p‐nitrophenol reduction by glycerol: A DFT investigation

AbstractReducing p‐nitrophenol (PNP) to p‐aminophenol is an industrially relevant synthesis. Nevertheless, only a few heterogeneous catalysts have been evaluated for the reduction of PNP by glycerol. Appropriate quantum computational studies can screen potential catalysts for this crucial green reaction. The present research investigates the catalytic activities of Pd@Ag and Ni@Ag core‐shell nanogeometries toward PNP reduction by glycerol through density functional theory (DFT) calculations. The central atom of a geometry‐optimized 13‐atom Ag cluster was replaced by Pd and Ni atoms to create the core‐shell morphologies. The interaction energies of PNP and glycerol with each of the (metal/bimetallic) clusters were evaluated by DFT calculations to find the best PNP and glycerol molecule orientation with the respective bimetallic cluster. Electrostatic potential surface and natural bond orbital analyses were performed to study the charge distribution and transfer between atomic orbitals. The frequencies of vibrational modes in isolated PNP/glycerol structures were compared to those when these molecules were in the presence of the different metal clusters to infer the effect of the interactions. All performed analyses indicated improved catalytic activity toward PNP reduction by glycerol upon Ni‐doping of the Ag13 cluster.

Sigma-Hole and Lone-Pair-Hole Site-Based Interactions of Seesaw Tetravalent Chalcogen-Bearing Molecules with Lewis Bases.

For the first time, sigma (σ)- and lone-pair (lp)-hole site-based interactions of SF4 and SeF4 molecules in seesaw geometry with NH3 and FH Lewis bases were herein comparatively investigated. The obtained findings from the electrostatic potential analysis outlined the emergence of sundry holes on the molecular entity of the SF4 and SeF4 molecules, dubbed the σ- and lp-holes. The energetic viewpoint announced splendid negative binding energy values for σ-hole site-based interactions succeeded by lp-hole analogues, which were found to be -9.21 and -0.50 kcal/mol, respectively, for SeF4···NH3 complex as a case study. Conspicuously, a proper concurrence between the strength of chalcogen σ-hole site-based interactions and the chalcogen's atomic size was obtained, whereas a reverse pattern was proclaimed for the lp-hole counterparts. Further, a higher preference for the YF4···NH3 complexes with elevated negative binding energy was promulgated over the YF4···FH ones, indicating the eminent role of Lewis basicity. The indications of the quantum theory of atoms in molecules generally asserted the closed-shell nature of all the considered interactions. The observation of symmetry-adapted perturbation theory revealed the substantial contributing role of the electrostatic forces beyond the occurrence of σ-hole site-based interactions. In comparison, the dispersion forces were specified to govern the lp-hole counterparts. Such emerging findings would be a gate for the fruitful forthcoming applications of chalcogen bonding interactions in crystal engineering and biological systems.

Tutorial: Electrodynamic balance methods for single particle levitation and the physicochemical analysis of aerosol

Single particle levitation methods are a powerful subset of aerosol instrumentation that allow a wide range of particle properties and processes to be explored. One of the most common forms of single particle levitation uses electric fields and is generally referred to as an electrodynamic balance (EDB). There are many different kinds of EDB's that have been designed with different applications in mind, and a corresponding array of analytical tools have been developed to characterize particles held in these traps. In this tutorial, we review the design and development of the EDB and discuss a range of analytical methods, including electrostatic analysis, light scattering, spectroscopy, and imaging, that allow for measurements of hygroscopic growth, volatility, surface tension and viscosity, diffusion, and phase and morphology. We go on to review recent advanced analytical methods using mass spectrometry to probe particle composition. This review is intended to provide readers with the basic knowledge to set up an EDB platform, design measurement protocols based on the available analytical tools, and run experiments to probe the fundamental properties of aerosol particles relevant to their role in the atmosphere, impacts on clouds and climate, effects on air quality, role in health and disease, and applications in industrial processes.

A DFT and QTAIM insight into ethylene oxide adsorption on the surfaces of pure and metal-decorated inorganic fullerene-like nanoclusters

In this industrial era, the use of low-dimensional nanomaterials as gas sensors for environmental monitoring has received enormous interest. To develop an effective sensing method for ethylene oxide (EO), DFT computations are conducted using method ωB97X-D and B3LYP with 6-31G(d,p) basis set to evaluate the adsorption behavior of ethylene oxide gas on the surfaces of pristine, as well as Scandium and Titanium decorated B12N12, Al12N12, and Al12P12 nanocages. Several properties like structural, physical, and electronic are studied methodically to better understand the sensing behavior. Scandium-decorated aluminum phosphate and boron nitride nanocages were shown to perform better in terms of adsorption properties. The short recovery time observed in this study is beneficial for the repetitive use of the gas sensor. The Natural Bond Orbital and molecular electrostatic potential analysis demonstrated a substantial quantity of charge transfer from adsorbate to adsorbents. The bandgap alternation after adsorption shows an influence of adsorption on electronic properties. The interactions of adsorbate and adsorbents are further studied using the ultraviolet–visible predicted spectrum, and quantum theory of atoms in molecules all of which yielded promising findings.

In vitro and in silico perspectives on the activation of antioxidant responsive element by citrus-derived flavonoids.

Oxidative stress plays an essential role in the pathogenesis of chronic diseases. Disrupting the Keap1-Nrf2 pathway by binding Keap1 is identified as a potential strategy to prevent oxidative stress-related chronic diseases. Therefore, of special interest is the utilization of dietary antioxidations from citrus, including narirutin, naringenin, hesperetin, hesperidin, naringin, neohesperidin dihydrochalcone, neohesperidin, and nobiletin, has been exploited as a prospective way to treat or prevent several human pathologies as Keap1-Nrf2 inhibitors for modulation of antioxidant properties. To probe into the structural foundation of the molecular identification of citrus-derived antioxidations, we calculated the antioxidant responsive element activation ability of citrus-derived flavonoids after binding with Keap1. Also, the quantum chemistry properties and binding mode were performed theoretically with frontier molecular orbitals, molecular electrostatic potential analysis, molecular docking, and absorption, distribution, metabolism, excretion (ADME) calculation. Experimental findings combining computational assays revealed that the tested citrus-derived flavonoids can be grouped into strong agonists and weak agonists. The citrus-derived antioxidations were well housed in the bound zone of Keap1 via stable hydrogen bonding and hydrophobic interaction. Eventually, three of eight antioxidations were identified after ADME and physicochemical evaluations. The citrus-derived flavonoids were identified as potential dietary antioxidants of the Keap1-Nrf2 interaction, and can be used to improve oxidative stress-related chronic diseases.

A novel salt- and organic solvent-tolerant phosphite dehydrogenase from Cyanothece sp. ATCC 51142.

Phosphite dehydrogenase (PtxD) is a promising enzyme for NAD(P)H regeneration. To expand the usability of PtxD, we cloned, expressed, and analyzed PtxD from the marine cyanobacterium Cyanothece sp. ATCC 51142 (Ct-PtxD). Ct-PtxD exhibited maximum activity at pH 9.0°C and 50°C and high stability over a wide pH range of 6.0-10.0. Compared to previously reported PtxDs, Ct-PtxD showed increased resistance to salt ions such as Na+, K+, and NH4 +. It also exhibited high tolerance to organic solvents such as ethanol, dimethylformamide, and methanol when bound to its preferred cofactor, NAD+. Remarkably, these organic solvents enhanced the Ct-PtxD activity while inhibiting the PtxD activity of Ralstonia sp. 4506 (Rs-PtxD) at concentrations ranging from 10% to 30%. Molecular electrostatic potential analysis showed that the NAD+-binding site of Ct-PtxD was rich in positively charged residues, which may attract the negatively charged pyrophosphate group of NAD+ under high-salt conditions. Amino acid composition analysis revealed that Ct-PtxD contained fewer hydrophobic amino acids than other PtxD enzymes, which reduced the hydrophobicity and increased the hydration of protein surface under low water activity. We also demonstrated that the NADH regeneration system using Ct-PtxD is useful for the coupled chiral conversion of trimethylpyruvic acid into L-tert-leucine using leucine dehydrogenase under high ammonium conditions, which is less supported by the Rs-PtxD enzyme. These results imply that Ct-PtxD might be a potential candidate for NAD(P)H regeneration in industrial applications under the reaction conditions containing salt and organic solvent.