Enhancement Of Reaction Rate Research Articles

Promotion of the catalytic polymerization of hydroquinone towards humic-like substances by graphitic carbon nitride

The utilization of graphitic carbon nitride (C3N4) to enhance the oxidative polymerization of hydroquinone (HQ) within manganese dioxide (MnO2) systems was investigated. C3N4, a Lewis base enriched with nitrogen, acted as a bridge through π − π interactions between metal oxides and polyphenols. These interactions increased the affinity of the reactants, resulting in an enhanced reaction rate of six-fold, accelerated browning, and improved complex stability of C3N4. HQ.MnO2 complex. As a result, a humic-like substance (HS) was rapidly formed with improved surface morphology and larger particle sizes. Electron transfer of HQ.MnO2 promoted by C3N4 played a crucial role in HQ oxidation, expanding atomic distance and composite morphology. Theoretical calculations supported the experimental results, indicating strong affinity and higher binding energies in the C3N4. HQ.MnO2 complex. The complex had a more stable structure with a narrower HOMO-LUMO gap, facilitating HS formation. 13C and 1H NMR spectra confirmed the experimental-theoretical agreement.

Numerical study on hydrogen heterogeneous reaction characteristic in a micro catalytic combustor with blunt body

A numerical investigation has been conducted to explore the effect of an inserted blunt body on the heterogeneous reaction (HTR) characteristics in a micro-catalytic combustor operating with premixed hydrogen/air. The two-dimensional numerical model incorporates a comprehensive heterogeneous reaction mechanism of hydrogen employed by experimental verification. The influences of blockage ratio at various inlet velocities have been investigated to obtain optimized design parameters of the combustor. The findings of this research highlight analysis of the positive influence of an inserted blunt body within the combustor, including enhancement of chemical reaction rate and hydrogen conversion ratio. Numerical results shows that the gaseous mixture between the blunt body and catalytic surface noticed a considerable velocity increase, leading to a greater adsorption–desorption of bulk species on the catalytic surface. At the same inlet velocity, the hydrogen conversion ratio gradually increases with higher blockage ratios. When the blockage ratio is less than or equal to 0.6, the average inner wall temperature is positively affected by the increased blockage ratio. However, the effect becomes negative at higher blockage ratios (0.8). The Pr (Prandtl number) number near the gas–solid interface adjacent to the blunt body initially decreases and then increases, while Nu/Nu0 (Nusselt number) and Pe (Peclet number) exhibit an initial increase followed by a decrease. The presence of the blunt body leads to a reduction in the cross-sectional area of the channel, causing an acceleration in fluid velocity near the blunt body and exerting an impact on the boundary layer near the gas–solid interface. This indicates that the addition of the blunt body reduces the boundary layer thickness and enhances the mass and heat transfer characteristics in the region. The study reveal that as the blockage ratio increases, the overall field synergy of the combustor initially increases and then decreases. The peak field synergy is attained at an optimal blocking ratio of 0.6. The findings of this study have important implications for the design of micro-scale combustors.

Impact of Pycnonuclear Fusion Uncertainties on the Cooling of Accreting Neutron Star Crusts

The observation of X-rays during quiescence from transiently accreting neutron stars provides unique clues about the nature of dense matter. This, however, requires extensive modeling of the crusts and matching the results to observations. The pycnonuclear fusion reaction rates implemented in these models are theoretically calculated by extending phenomenological expressions and have large uncertainties spanning many orders of magnitude. We present the first sensitivity studies of these pycnonuclear fusion reactions in realistic network calculations. We also couple the reaction network with the thermal evolution code dStar to further study their impact on the neutron star cooling curves in quiescence. Varying the pycnonuclear fusion reaction rates alters the depth at which nuclear heat is deposited although the total heating remains constant. The enhancement of the pycnonuclear fusion reaction rates leads to an overall shallower deposition of nuclear heat. The impurity factors are also altered depending on the type of ashes deposited on the crust. These total changes correspond to a variation of up to 9 eV in the modeled cooling curves. While this is not sufficient to explain the shallow heat source, it is comparable to the observational uncertainties and can still be important for modeling the neutron star crust.

Conventional Versus Microwave Induced Synthesis and Biological Evolution of Coumarin Substituted Thioaryl Pyrazolyl Pyrazoline

Aim: This is a comparative study of some new coumarin substituted thioaryl pyrazolyl pyrazoline. Methods: The target compounds were synthesized using both conventional as well as microwave irradiation by reaction of coumarin chalcones with different substituted hydrazine hydrates and aryl hydrazines to give the resultant pyrazoline derivatives. Microwave reaction, enhanced or-ganic reactions, and reduced reaction time led to better yields and selectivity than conventional methods. Results: The obtained compounds were characterized by different spectroscopic analysis includ-ing IR, 1H-NMR, 13C-NMR, mass spectroscopy and elemental-analysis and evaluated for their antimicrobial screening against a representative panel of bacteria (Bacillus subtilis, Staphylococ-cus aureus, Escherichia coli, Salmonella typhi) and fungi (Aspergillus niger, Candida albicans). Conclusion: In the present study, we have synthesized coumarin pyrazoline derivatives clubbed with benzofuran pyrazole via both conventional and microwave irradiation and also subjected to antibacterial and antifungal studies. Synthesis of target compounds by the microwave irradiation enhanced reaction rate and reduced reaction time led to better yields and selectivity than conven-tional methods. The study of antibacterial and antifungal activities revealed that all the com-pounds exhibited reasonable to excellent activities against the pathogenic strains.

Accelerating DNA computing via freeze-thaw cycling.

DNA computing harnesses the immense potential of DNA molecules to enable sophisticated and transformative computational processes but is hindered by low computing speed. Here, we propose freeze-thaw cycling as a simple yet powerful method for high-speed DNA computing without complex procedures. Through iterative cycles, we achieve a substantial 20-fold speed enhancement in basic strand displacement reactions. This acceleration arises from the utilization of eutectic ice phase as a medium, temporarily increasing the effective local concentration of molecules during each cycle. In addition, the acceleration effect follows the Hofmeister series, where kosmotropic anions such as sulfate (SO42-) reduce eutectic phase volume, leading to a more notable enhancement in strand displacement reaction rates. Leveraging this phenomenon, freeze-thaw cycling demonstrates its generalizability for high-speed DNA computing across various circuit sizes, achieving up to a remarkable 120-fold enhancement in reaction rates. We envision its potential to revolutionize molecular computing and expand computational applications in diverse fields.

Impact of hydrodynamic dispersion on mixing-induced reactions under radial flows

Mixing-induced reaction fronts play a key role in a range of subsurface processes. In many applications, reactive fronts develop under radial flows, where a reactant is injected and displaces another. Analytical solutions for reactive front dynamics under radial flows have been derived under the assumption of a constant diffusion coefficient. However, the impact of mechanical dispersion still remains unexplored. We investigate this question here by deriving approximate analytical expressions for the reaction front properties as a function of time, dispersion length and Péclet/Damköhler number, as well as from corresponding numerical simulations. Our results indicate that mechanical dispersion leads to a more advanced front and enhanced reaction rate, compared to the dispersion-free scenario. This leads to new scaling laws for the front position, width and reaction rate. We discuss the implications of these findings for field conditions over a range of temporal and spatial scales. Under most realistic scenarios, dispersion is expected to be dominant over diffusion, suggesting a broad relevance of these results.

Copper and Silver Catalysis in the (3 + 2) Cycloaddition of Neutral Three-Atom Components with Terminal Alkynes.

The introduction of the copper-catalyzed azide-alkyne coupling (CuAAC) to 1,3-dipolar cycloadditions was pivotal to their popularization in synthetic chemistry and to their application to multiple other domains of science. The reaction rate enhancement observed when coinage metal acetylide intermediates are involved in the cyclization process greatly expanded the structural and conditional range in which (3 + 2) cycloadditions may take place with terminal alkynes. Herein, we report that comparable rate enhancements, in nature and level, are induced by copper and silver catalysts in the intramolecular (3 + 2) cycloaddition of terminal alkynes with "neutral" three-atom components (TACs), specifically alkynyl sulfides. Through careful observations amidst reaction optimization, experimental, and DFT mechanistic studies, a pathway involving a proton-coupled cyclometallation key step is proposed. The sets of catalytic conditions that have been developed allow us to overcome several scope limitations previously presented by the thermally promoted (3 + 2) cycloaddition of "neutral" TACs, thus expanding their synthetic and applicative potential.

Enhanced Mixing and Reaction in Converging Flows: Theory and Pore‐Scale Imaging

AbstractMixing fronts at the interface of opposing flows are compressed at a constant rate. The resulting exponential stretching of fluid elements leads to enhanced chemical gradients and biogeochemical processes. This process is similar as what occurs in the pore space of 3D chaotic flows. However, it is so far not known how such fluid compression controls the amplitude of mixing and reaction rates in porous media. Here we derive analytical predictions for the mixing width, the maximum reaction rate and the reaction intensity in compressed mixing fronts as a function of the Péclet and Damköhler numbers. We developed an experimental setup providing pore scale measurements of mixing and reaction rates in mixing fronts at the interface of converging flows. The theory accurately predicts the scaling of mixing and reaction with the Péclet number both in porous micromodels and simple Hele‐Shaw cells. Additionally, we found that the presence of pore scale heterogeneities in the porous micromodels enhances reaction rates by a factor of 4 compared to the Hele‐Shaw cells. Using numerical simulations of pore scale velocity fields, we attributed this phenomenon to the enhancement of pore‐scale compression due to the presence of grains in accelerating flows. These findings provide new insights into the dynamics of mixing‐induced reactions in porous media.

A polysaccharide utilization locus from Chitinophaga pinensis simultaneously targets chitin and β-glucans found in fungal cell walls.

In nature, complex carbohydrates are rarely found as pure isolated polysaccharides. Instead, bacteria in competitive environments are presented with glycans embedded in heterogeneous matrices such as plant or microbial cell walls. Members of the Bacteroidota phylum thrive in such ecosystems because they are efficient at extracting nutrients from complex substrates, secreting consortia of synergistic enzymes to release metabolizable sugars. Carbohydrate-binding modules (CBMs) are used to target enzymes to substrates, enhancing reaction rate and product release. Additionally, genome organizational tools like polysaccharide utilization loci (PULs) ensure that the appropriate set of enzymes is produced when needed. In this study, we show that the soil bacterium Chitinophaga pinensis uses a PUL and several CBMs to coordinate the activities of enzymes targeting two distinct polysaccharides found in fungal cell walls. We describe the enzymatic activities and carbohydrate-binding behaviors of components of the fungal cell wall utilization locus (FCWUL), which uses multiple chitinases and one β-1,3-glucanase to hydrolyze two different substrates. Unusually, one of the chitinases is appended to a β-glucan-binding CBM, implying targeting to a bulk cell wall substrate rather than to the specific polysaccharide being hydrolyzed. Based on our characterization of the PUL's outer membrane sensor protein, we suggest that the FCWUL is activated by β-1,3-glucans, even though most of its enzymes are chitin-degrading. Our data showcase the complexity of polysaccharide deconstruction in nature and highlight an elegant solution for how multiple different glycans can be accessed using one enzymatic cascade. IMPORTANCE We report that the genome of the soil bacterium Chitinophaga pinensis encodes three multi-modular carbohydrate-active enzymes that work together to hydrolyze the major polysaccharide components found in fungal cell walls (FCWs). The enzymes are all encoded by one polysaccharide utilization locus and are co-expressed, potentially induced in the presence of β-1,3-glucans. We present biochemical characterization of each enzyme, including the appended carbohydrate-binding modules that likely tether the enzymes to a FCW substrate. Finally, we propose a model for how this so-called fungal cell wall utilization locus might enable C. pinensis to metabolize both chitin and β-1,3-glucans found in complex biomass in the soil.

Study on Oxy-Methane Flame Stability in a Cylindrical Porous Medium Burner

Combustion in a porous medium can be beneficial for enhancing reaction rate and temperature uniformity. Therefore, considering the combination with oxy-fuel combustion can address some shortcomings in oxy-fuel burners, a cylindrical two-layer porous burner model is established based on OpenFOAM in this paper. A two-temperature equation model is adopted for the simulation of the heat transfer process. The CH4 skeletal kinetic mechanism is adopted for complex chemistry integration based on OpenSMOKE++. Corresponding experimental methods were used for complementary studies. The walls of the burner are wrapped with three types of thermal insulation materials to present different levels of heat loss. The results show that considering the convection and radiative heat loss of the burner wall, the temperature near the wall is reduced by more than 300 K compared to the adiabatic condition. As a result, the flame propagation speed and CO oxidation rate slowed down. The stable range will be destructively narrowed by more than 50%, and CO emissions will increase by more than 10 times. These defects will be aggravated by increasing the diameter of the burner. It is observed that when the diameter of the burner increases from the initial 5 cm to 10 cm, the effect of heat loss on the stable range is insignificant.

A Numerical Study on Premixed Turbulent Planar Ammonia/Air and Ammonia/Hydrogen/Air Flames: An Analysis on Flame Displacement Speed and Burning Velocity

The economic storage and transportation of ammonia (NH3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {NH}_3$$\\end{document}), and its capability to be thermally decomposed to hydrogen (H2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {H}_2$$\\end{document}) make it a potential carbon-free synthetic fuel for the future. To comprehend the fundamental characteristics of NH3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {NH}_3$$\\end{document} as a primary fuel enriched with H2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {H}_2$$\\end{document} under low turbulent premixed flame conditions, three quasi direct numerical simulations (quasi-DNS) with detailed chemistry and the mixture-averaged transport model are conducted under decaying turbulence herein. The Karlovitz number is fixed to 4.28 for all the test conditions. The blending ratio (α\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\alpha$$\\end{document}), specifying the hydrogen concentration in the ammonia/hydrogen mixture, varies from 0.0 to 0.6. The results reveal that the mean value of the density-weighted flame displacement speed (Sd∗\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$S_{\ extrm{d}}^{*}$$\\end{document}) is similar to (higher than) the unstrained premixed laminar burning velocity (SL0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$S_{\ extrm{L}}^{0}$$\\end{document}) for NH3/\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {NH}_3/$$\\end{document}air flame (NH3/H2/\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {NH}_3/\\hbox {H}_2/$$\\end{document}air flames). Furthermore, the performance of two extrapolation relations for estimating Sd∗\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$S_{\ extrm{d}}^{*}$$\\end{document} as linear and non-linear functions of flame front curvature is discussed thoroughly. The performances of both models are almost similar when evaluating the data near the leading edge of the flame. However, the non-linear one offers more accurate results near the trailing edge of the flame. The results show that the mean flame stretch factor increases with increasing the blending ratio, suggesting that the mean flamelet consumption velocity deviates from SL0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$S_{\ extrm{L}}^{0}$$\\end{document} by enriching the mixture with H2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {H}_2$$\\end{document}. The mean value of the local equivalence ratio (ϕ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\phi$$\\end{document}) for the turbulent NH3/\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {NH}_3/$$\\end{document}air flame is almost equal to its laminar counterpart, while it deviates significantly for NH3/H2/\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {NH}_3/\\hbox {H}_2/$$\\end{document}air flames. In addition, the local equivalence ratio for the flame front with positive curvature values is higher than the negatively curved regions for NH3/H2/\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {NH}_3/\\hbox {H}_2/$$\\end{document}air flames due to H2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {H}_2$$\\end{document} preferential diffusion. Furthermore, the results indicate that hydrogen is consumed faster in positively curved regions compared to the negatively curved zones due to enhanced reaction rates of specific chemical reactions.

Direct electron transfer kinetics of histamine dehydrogenase at air plasma-treated graphite nanofibers

As histamine is one of the important mediators for allergic reactions, its efficient detection methods and real-time monitoring systems are required for food analyses and drug discoveries to suppress allergic reactions. Although histamine dehydrogenase (HmDH) is a promising candidate for developing enzyme-based electrochemical biosensors, some electron mediators are frequently employed to observe electrocatalytic currents for histamine oxidation. Here, direct electrochemistry of HmDH was studied at the surface of graphite nanofibers (GNFs), which provide active reaction sites for redox species. Air plasma-treated GNFs were used for constructing a three-dimensional network that works both as an electrical nanowire and an enzyme support. Even though the amount of oxygen-containing functional groups didn’t significantly increase at the GNF surface with increase in the air plasma treatment time, direct electron transfer from reduced HmDH by histamine to the GNFs was improved probably due to capped and curvature of the graphite edge sites with oxygen-containing functional groups, which were generated by the air plasma treatment. The air plasma-treated GNFs also allowed enhancement of the complex-formation reaction rate of HmDH with histamine, as the air plasma treatment time increased.

Synthesis of Imidazole-Based Molecules under Ultrasonic Irradiation Approaches.

Imidazole-based compounds are a series of heterocyclic compounds that exhibit a wide range of biological and pharmaceutical activities. However, those extant syntheses using conventional protocols can be time-costly, require harsh conditions, and result in low yields. As a novel and green technique, sonochemistry has emerged as a promising method for organic synthesis with several advantages over conventional methods, including enhancing reaction rates, improving yields, and reducing the use of hazardous solvents. Contemporarily, a growing body of ultrasound-assisted reactions have been applied in the preparation of imidazole derivatives, which demonstrated greater benefits and provided a new strategy. Herein, we introduce the brief history of sonochemistry and focus on the discussion of the multifarious approaches for the synthesis of imidazole-based compounds under ultrasonic irradiation and its advantages in comparison with conventional protocols, including typical name-reactions and various sorts of catalysts in those reactions.

The Influence of Nonlocal Metal-Dielectric Environments on Physical and Chemical Processes.

ConspectusPlasmonic nanolayers and laminar metallic/dielectric multilayers were originally developed for optical cloaking applications and lensing applications that could potentially image objects whose size was below the diffraction limit. These assemblies were initially formed from gold or silver nanorods grown within an alumina mesh. However, more recently, assemblies with similar properties have also been prepared by sequential thin-layer deposition of alternating layers of gold and magnesium fluoride (MgF2). These metal/dielectric composite materials enable control of the dielectric constant in the directions perpendicular to the layers and balance the real and imaginary dielectric constants of the assembly such that the speed and the amplitude of the waves traveling through the assembly are not attenuated.In this Account, we will also focus on a few of the applications ranging from surface wetting to fluorescence quenching to enhancement of photochemical reactions. First, we will share an introduction to processes used to create these materials, which are combinations of low refractive index metals and transparent higher index materials arranged in a scalable repeating fashion. Two fabrication methods were employed: an electrochemical deposition of Ag nanorods into an anodized alumina matrix which produced materials with an anisotropic negative refractive index material within the plane of the film and lamellar metal/dielectric layers in which the negative index perpendicular to the growth direction. These alternating layers of plasmonic metals and dielectric materials were ultimately chosen to prepare films for further testing, because of their relative ease of fabrication. We will continue with a discussion of a few of the applications of both of these nonlocal dielectric composite materials including more specialized plasmonic, composite, and hyperbolic metamaterials including fluorescence quenching, photochemical reactions, and surface wetting. In each of these applications, the unique response caused by the enhancement of the electric field and the interface between hyperbolic materials and plasmonic materials as they interact photophysically with their near neighbors is presented. In each of the applications, the enhanced electric field extends from the composite substrate layer to interact with its near neighbors and beyond. The presence of this extended interaction can be observed in the form of decreased emission lifetime, enhancement of photochemical reaction rates, and changes in the surface energies measured by contact angle goniometry. In this Account, all of these situations will be addressed. Finally, we will conclude with a summary and vision for the future as well as a discussion of the unique challenges and opportunities available as research active faculty at an HBCU.

Synergistic influence of vanadium pentoxide-coupled graphitic carbon nitride composite for photocatalytic degradation of organic pollutant: Stability and involved Z-scheme mechanism

The removal of dyes from wastewater by photocatalytic technologies has received substantial attention in recent years. In the present study, novel Z-scheme V2O5/g-C3N4 photocatalytic composites were organized via simple hydrothermal processes and a sequence of several characterization aspects. The degradation results showed that the optimum Z-scheme GVO2 heterostructure composite photocatalysts (PCs) had a better efficiency (90.1%) and an apparent rate (0.0136 min−1) for the methylene blue (MB) aqueous organic dye degradation, which was about 6.18-fold higher than that of pristine GCN catalyst. Meanwhile, the GVO2 heterostructured PCs showed better recycling stability after five consecutive tests. Moreover, the free radical trapping tests established that •O2− and h+ species were the prime reactive species in the photocatalytic MB degradation process in the heterostructured PCs. The photocatalytic enhanced activity was primarily recognized as the synergistic interfacial construction of the Z-scheme heterojunctions among V2O5 and GCN, which improved the separation/transfer, lower recombination rate, extended visible-light utilization ability, and enhanced reaction rate. Therefore, the existing study affords a simple tactic for the development of a direct Z-scheme for photocatalytic heterojunction nanomaterials for potential environmental remediation applications.

Multienzyme‐Mimetic Activity of Gold/Cerium Oxide Nanozyme

AbstractRedox‐active nanozymes offer low‐cost controlled synthesis, high stability, and tunable catalytic properties over natural enzymes, which have attracted wide attention in the field of disease diagnosis and treatment. However, the improvement of catalytic activity remains an important challenge for nanozymes. Herein, the Au/CeO2 nanozymes is developed to achieve enhanced multiple enzyme‐mimetic activity. The Au/CeO2 nanozymes at 5% doping possess best peroxidase‐like activity with threefold higher catalytic rate than CeO2. For catalase‐mimic catalysis, the Au/CeO2 nanozymes at 5% doping also exhibited a 1.5‐fold enhanced reaction rate higher than pure CeO2. The superoxide dismutase (SOD)‐like capacity of Au/CeO2 nanozymes is proportional to Au content. The Au/CeO2 nanozymes at 10% doping show optimal SOD‐like capacity of 60.2 U mg−1. In vitro experiments validate the regulation ability of intracellular oxidative stress and inflammation. Au/CeO2 nanozymes can reduce lipopolysaccharide‐ or H2O2‐induced oxidative damage by scavenging excess ROS in nerve cell. Therefore, Au/CeO2 can be used as a promising antioxidant in disease treatment, and the study offers general guidelines for achieving enhanced biocatalytic property through atomic doping.

Tuning the Interfacial Electrical Field of Bipolar Membranes with Temperature and Electrolyte Concentration for Enhanced Water Dissociation

A coupled experimental and numerical study was performed for a fundamental understanding of the impact of operating conditions, i.e., temperature and electrolyte concentration, as well as interfacial abruptness, on the bipolar membrane (BPM) performance. A comprehensive multiphysics-based model was developed to optimize the operation condition and interfacial properties of BPM, and the model was used to guide the design and engineering of high-performing BPMs. The origin of the enhanced BPM performance at a high temperature was identified, which was attributed to the intrinsic reaction rate enhancement as well as the increase in electrolyte ionic conductivity. The experimentally demonstrated current density–voltage characteristics of BPMs clearly exhibited three distinctive regions of operation: ion-crossover region, water dissociation region, and water-limiting region, which agreed well with the multiphysics simulation results. In addition, the model revealed that a sharper interfacial abruptness led to improved BPM performance due to the enhanced interfacial electric field at the water dissociation region. The decrease of the electrolyte concentration, which increased the dielectric constant of the electrolyte, enhanced the interfacial electric field, leading to improved electrochemical performances. The present study offers an in-depth perspective to understand the species transport as well as water dissociation mechanism under various operation conditions and membrane designs, providing the optimal operation conditions and membrane designs for maximizing the BPM performance at high current densities.

Electric‐Field‐Induced Organic Transformations

AbstractExperiments showed that the existence of electric fields in non‐redox processes may alter the catalytic activity, rate enhancement, and selection of organic reactions. It is expected that the interaction between electric fields and chemical reactions will create new avenues for producing materials with desired properties in several chemical disciplines, including synthetic organic chemistry, catalysis, nanotechnology, membrane technology, and enzyme catalysis. Specifically, in this review, we discuss the elegant experimental investigations carried out using the scanning tunneling microscope, the interfacial electric field, and designed local electric fields. The results of these studies are remarkable, leading to new information on the function of electric fields in controlling chemical reactivity and selectivity in different reactions and offering a glimpse of the great potential of electrostatic fields. This article not only presents the core concepts of field‐induced chemical transformations but also illustrates the potential use of electric field catalysis in chemistry and other fields.

13C NMR and Mass Spectral Analysis of 2, 5-Diarylamino-3, 6-Dichloro-1, 4-Benzoquinones Synthesized By Microwave Irradiation

Abstract: The substituted p-benzoquinones are potentially bioactive and they represent a class of compound with wide spectrum of biological activity. The microwave synthesis has received attention as new strategy for the organic synthesis due to the fact that many reactions seem to proceed with much alacrity under such conditions as opposed to thermal-assisted reactions. Apart from the enhanced reaction rate and higher yield, solvent free MWI method provided several advantages such as safe, clean and green reaction conditions, opportunity to work with open vessel, possibility to upscale the synthesis to multi-gram amount, reproducibility and convenient work-up. The characterization was done by 13C NMR and mass Spectral analysis.

Family 92 carbohydrate-binding modules specific for β-1,6-glucans increase the thermostability of a bacterial chitinase

In biomass-processing industries there is a need for enzymes that can withstand high temperatures. Extensive research efforts have been dedicated to finding new thermostable enzymes as well as developing new means of stabilising existing enzymes. The attachment of a stable non-catalytic domain to an enzyme can, in some instances, protect a biocatalyst from thermal denaturation. Carbohydrate-binding modules (CBMs) are non-catalytic domains typically found appended to biomass-degrading or modifying enzymes, such as glycoside hydrolases (GHs). Most often, CBMs interact with the same polysaccharide as their enzyme partners, leading to an enhanced reaction rate via the promotion of enzyme-substrate interactions. Contradictory to this general concept, we show an example of a chitin-degrading enzyme from GH family 18 that is appended to two CBM domains from family 92, both of which bind preferentially to the non-substrate polysaccharide β-1,6-glucan. During chitin hydrolysis, the CBMs do not contribute to enzyme-substrate interactions but instead confer a 10–15 °C increase in enzyme thermal stability. We propose that CBM92 domains may have a natural enzyme stabilisation role in some cases, which may be relevant to enzyme design for high-temperature applications in biorefinery.