ANALYSIS OF STRUCTURE EVOLUTION AND ENVIRONMENTAL CONDITIONS OF TROPICAL CYCLONES OVER THE WESTERN NORTH PACIFIC DURING EXTRATROPICAL TRANSITION

Fifty-eight extratropical transition(ET) cases in the years 2000-2008, including 2,021 observations(at 6-hour intervals), over the western North Pacific are analyzed using the cyclone phase space(CPS) method, in an effort to get the characteristics of the structure evolution and environmental conditions of tropical cyclones(TCs) during ET over this area. Cluster analysis of the CPS dataset shows that strong TCs are more likely to undergo ET. ET begins with the increment of thermal asymmetry in TCs, along with the generation and intensification of an upper-level cold core, and ends with the occurrence of a lower-level cold core. ET lasts an average duration of about 28 hours. Dynamic composite analysis of the environmental field of different clusters shows that, in general, when TCs move northward,they are gradually embedded in the westerlies and gradually transform into extratropical cyclones under the influence of the mid-and higher-latitude baroclinic systems. As for those TCs which complete ET, there is always much greater potential vorticity gradient in the northwest of them and obvious water vapor transport channels in the environment.

Computational screening and design of nanoporous membranes for efficient carbon isotope separation

Stable isotopes have been routinely used in chemical sciences,medical treatment and agricultural research.Conventional technologies to produce high-purity isotopes entail lengthy separation processes that often suffer from low selectivity and poor energy efficiency.Recent advances in nanoporous materials open up new opportunities for more efficient isotope enrichment and separation as the pore size and local chemical environment of such materials can be engineered with atomic precision.In this work,we demonstrate the unique capability of nanoporous membranes for the separation of stable carbon isotopes by computational screening a materials database consisting of 12,478 computation-ready,experimental metal-organic frameworks(MOFs).Nanoporous materials with the highest selectivity and membrane performance scores have been identified for separation of^(12)CH_4/^(13)CH_4 at the ambient condition(300 K).Analyzing the structural features and metal sites of the promising MOF candidates offers useful insights into membrane design to further improve the performance.An upper limit of the efficiency has been identified for the separation of^(12)CH_4/^(13)CH_4 with the existing MOFs and those variations by replacement of the metal sites.

Recent progress in enzymatic functionalization of carbon-hydrogen bonds for the green synthesis of chemicals

Enzymatic reactions take place with high chemo-, regio-, and stereo-selectivity, appealing for the direct functionalization of abundant and inexpensive compounds with C-H bonds to make fine chemicals such as high-value intermediates and pharmaceuticals. This review summarizes recent progress in the enzymatic functionalization of C-H bonds with an emphasis on heme enzymes such as cytochrome P450 s, chloroperoxidase and unspecific peroxygenases. Specific examples are discussed to elucidate the applications of the molecular and process engineering approaches to overcome the challenges hindering enzymatic C-H functionalization. Also discussed is the recent development of the chemo-enzymatic cascade as an effective way to integrate the power of metal catalysis and enzymatic catalysis for C-H functionalization.

Ionic Distribution, Electrostatic Potential and Zeta Potential at Electrochemical Interfaces

Density functional theory is applied to predicting the structures and electrostatic potentials of planar electrochemical surfaces within the framework of the restricted primitive model where small ions are represented by charged hard spheres of equal diameter and the solvent is assumed to be a continuous dielectric medium. The hard-sphere contribution to the excess Helmholtz energy functional is evaluated using the modified fundamentalmeasure theory and the electrostatic contribution is obtained from the quadratic functional Taylor expansion using the second-order direct correlation function from the mean-spherical approximation. Numerical results for the ionic density profiles and the mean electrostatic potentials near a planar surface of various charge densities are in excellent agreement with molecular simulations. In contrast to the modified Gouy-Chapman theory, the present density functional theory correctly predicts the second layer formation and charge inversion of charged surfaces as observed in simulations and in experiments. The theory has also been tested with the zeta potentials of positively charged polystyrene particles in aqueous solutions of KBr. Good agreement is achieved between the calculated and experimental results.

Low‐temperature synthesis of graphitic carbon‐coated silicon anode materials

We report the synthesis of a high‐performance graphitic carbon‐coated silicon(Si@GC)composite material for lithium‐ion batteries via a scalable production route.Porous Si is produced from the magnesiothermic reduction of commercial silica(SiO2)precursor followed by low‐temperature graphitic carbon coating using glucose as the precursor.The obtained Si@GC composite achieves an excellent reversible specific capacity of 1195 mAh g−1 and outstanding cycle stability.The thick Si@GC anode(3.4 mg cm^−2)in full cells with commercial lithium iron phosphate cathode delivers a remarkable performance of 800 mAh g^−1 specific capacity and 2.7 mAh cm^−2 areal capacity as well as 93.6%capacity retention after 200 cycles.

An improved theoretical procedure for the pore-size analysis of activated carbon by gas adsorption

Amorphous carbon materials play a vital role in adsorbed natural gas(ANG) storage. One of the key issues in the more prevalent use of ANG is the limited adsorption capacity, which is primarily determined by the porosity and surface characteristics of porous materials. To identify suitable adsorbents, we need a reliable computational tool for pore characterization and, subsequently, quantitative prediction of the adsorption behavior. Within the framework of adsorption integral equation(AIE), the pore-size distribution(PSD) is sensitive to the adopted theoretical models and numerical algorithms through isotherm fitting. In recent years, the classical density functional theory(DFT) has emerged as a common choice to describe adsorption isotherms for AIE kernel construction. However,rarely considered is the accuracy of the mean-field approximation(MFA) commonly used in commercial software. In this work, we calibrate four versions of DFT methods with grand canonical Monte Carlo(GCMC) molecular simulation for the adsorption of CH_4 and CO_2 gas in slit pores at 298 K with the pore width varying from 0.65 to 5.00 nm and pressure from 0.2 to 2.0 MPa. It is found that a weighted-density approximation proposed by Yu(WDA-Yu) is more accurate than MFA and other non-local DFT methods. In combination with the trapezoid discretization of AIE, the WDA-Yu method provides a faithful representation of experimental data, with the accuracy and stability improved by 90.0% and 91.2%, respectively, in comparison with the corresponding results from MFA for fitting CO_2 isotherms. In particular, those distributions in the feature pore width range(FPWR)are proved more representative for the pore-size analysis. The new theoretical procedure for pore characterization has also been tested with the methane adsorption capacity in seven activated carbon samples.

Using probe molecule FTIR spectroscopy to identify and characterize Pt-group metal based single atom catalysts

单原子催化是提高贵金属利用率的有效手段,而表征单原子催化剂是理解单原子催化的基础.探针分子红外光谱可用于识别和定量催化剂样品中孤立的Pt族金属物种的浓度,从而得到负载的孤立的Pt族金属物种的局部几何形状、稳定性、活性及其分散性.本文讨论了该技术用于识别和表征含负载型孤立的Pt族金属原子催化剂的效能、应用、以及未来的发展方向.

Highly antibacterial rGO/Cu2O nanocomposite from a biomass precursor:Synthesis,performance,and mechanism

Reduced graphene oxide(rGO)has been widely used to fabricate electronics,sensors,photodetectors,and in other applications.However,the antibacterial performance of pristine rGO is relatively weak.The application of rGO in biomedical devices,smart food packaging,and water desalination membranes requires further improvement of rGO’s antibacterial abilities.Copper(I)oxide(Cu2O)is an effective antibacterial agent,which denatures protein and enhances the permeability of cell membranes.In this work,we report a simple method of synthesizing a highly antibacterial rGO/Cu2O nanocomposite from cellulose acetate,a derivative of abundant natural cellulose.The synthesized rGO/Cu2O nanocomposite was thoroughly characterized by Raman spectroscopy,X-ray powder diffraction(XRD),X-ray photoelectron spectroscopy(XPS),atomic force microscopy(AFM),scanning electron microscopy(SEM),high-resolution transmission electron microscopy(HRTEM),and scanning transmission electron microscopy(STEM).Then,the antibacterial abilities of rGO/Cu2O nanocomposite were evaluated and a bactericidal mechanism was revealed from the molecular biology perspective.Results indicate that our synthesized rGO/Cu2O nanocomposite owns strong antibacterial activity,mainly stemming from the uniformly incorporated Cu2O nanocrystals with a lateral size of 5–40 nm.

Electrochemical Biosensor for Rapid Detection of Viable Bacteria and Antibiotic Screening

We have developed a biosensor for the detection of live/viable bacteria based on the response of the conductive polymer 4-(3-pyrrolyl)butyric acid to glucose-induced metabolites.The polymer was electrochemically deposited and then functionalized with lectin through EDC/NHS chemistry to capture cells near the sensor surface and introduce selectivity for analytes.The addition of glucose to a three-electrode electrochemical cell containing 10 mM phosphate buffer and the bacteria-immobilized sensor produced an increase in the potential.When the bound bacteria were treated with antibiotics,the addition of glucose produced a notably reduced signal exhibiting the sensor’s potential to screen for the most effective antibiotic treatment.This biosensor having real-time responses,minimal sample preparation,and the ability to screen antibiotics demonstrates the speed,ease,and suitability essential for application in point-of-care services.The detection range was determined to be 6.0×10^(3)-9.2×10^(7)CFU/mL.

The First Attempt for Accounts of Environmental Chemistry and Technology Research

In the field of environmental chemical science and technology,researchers have been publishing high-quality research articles on a specific discovery as well as comprehensive reviews on a broader area.After multiple years of research and publication of individual reports,they are looking for a new venue for scientific communication,which will not only summarize a series of their past achievements but also further extend the discussion without including a comprehensive review of 200+articles.

A Dynamic Organic Structuring-Directing Agent for Pure-Silica-Zeolite AST and LTA Syntheses

Pure-silica-zeolite (PSZ ) 著名计算机生产厂商和 LTA 被使用一样的指导结构的代理人(SDA ) 成功地综合分子，但是在不同集中。动态器官的 SDA 被建议讨论在著名计算机生产厂商和 LTA 之间的阶段辨别的机制。数据建议进在不同集中由的更暗淡或更整齐的建筑群自我装配的 SDA 分子罐头 - 相互作用，和这些差别能被利用有选择地综合 PSZ 著名计算机生产厂商或 LTA。从 Liebau 的规则的这些偏差显示在在溶液的 SDA 化学，结构，和顺序的小面值硬币能在沸石合成的结构选择上有大影响。

Effects of continuously regenerating diesel particulate filters on regulated emissions and number-size distribution of particles emitted from a diesel engine

The effects of continuously regenerating diesel particulate filter （CRDPF） systems on regulated gaseous emissions, and number-size distribution and mass of particles emanated from a diesel engine have been investigated in this study. Two CRDPF units （CRDPF-1 and CRDPF-2） with different specifications were separately retrofitted to the engine running with European steady-state cycle （ESC）. An electrical low pressure impactor （ELPI） was used for particle number-size distribution measurement and mass estimation. The conversion/reduction rate （RcR） of hydrocarbons （HC） and carbon monoxide （CO） across CRDPF-1 was 83% and 96.3%, respectively. Similarly, the RCR of HC and CO and across CRDPF-2 was 91.8% and 99.1%, respectively. The number concentration of particles and their concentration peaks; nuclei mode, accumulation mode and total particles; and particle mass were highly reduced with the CRDPF units. The nuclei mode particles at downstream of CRDPF-1 and CRDPF-2 decreased by 99.9% to 100% and 97.8% to 99.8% respectively; and the particle mass reduced by 73% to 92.2% and 35.3% to 72.4%, respectively, depending on the engine conditions. In addition, nuclei mode particles increased with the increasing of engine speed due to the heterogeneous nucleation initiated by the higher exhaust temperature, while accumulation mode particles were higher at higher loads due to the decrease in the air-to-fuel ratio （A/F） at higher loads.

Application of electrochemical depassivation in PRB systems to recovery Fe^0 reactivity

Permeable reactive barriers （PRBs） show remarkable Cr（VI） removal performance. However, the diminished removal rate because of mineral fouling over time is the bottleneck for application of PRBs. The present study demonstrated that electrochemical depassivation was effective for recovering the Fe^0 reactivity, and minerals can be cleaned layer by layer with no secondary ion contamination and no transformation from Cr（III） to Cr（VI）. The removal recovery rate increased with increasing electrolysis voltage before reaching the optimal electrolysis voltage, and then decreased as the electrolysis voltage further increased. The recovery effect at electrolysis voltages of 5, 10, and 15 V show the same trend as a function of electrolysis time, where recovery rate first increased and then decreased after reaching the optimal electrolysis time. The Cr（VI） removal rate significantly decreased with increasing electrolysis distance. Furthermore, Fe^0 brush meshes electrode, Fe^0 fillings, and polyvinyl chloride （PVC） meshes separators were combined to create an Electro-PRB configuration for the caisson excavation construction technique, which lays the foundation for establishment of promising Electro-PRB systems to treat Cr（VI）-contaminated groundwater.

Alumina-coated Ag nanocrystal monolayers as surfaceenhanced Raman spectroscopy platforms for the direct spectroscopic detection of water splitting reaction intermediates

A novel Ag-alumina hybrid surface-enhanced Raman spectroscopy （SERS） platform has been designed for the spectroscopic detection of surface reactions in the steady state. Single crystalline and faceted silver （Ag） nanoparticles with strong light scattering were prepared in large quantity, which enables their reproducible self-assembly into large scale monolayers of Raman sensor arrays by the Langrnuir-Blodgett technique. The close packed sensor film contains high density of sub-nm gaps between sharp edges of Ag nanoparticles, which created large local electromagnetic fields that serve as ＂hot spots＂ for SERS enhancement. The SERS substrate was then coated with a thin layer of alumina by atomic layer deposition to prevent charge transfer between Ag and the reaction system. The photocatalytic water splitting reaction on a monolayer of anatase TiO2 nanoplates decorated with Pt co-catalyst nanoparticles was employed as a model reaction system. Reaction intermediates of water photooxidation were observed at the TiO2/solution interface under UV irradiation. The surface-enhanced Raman vibrations corresponding to peroxo, hydroperoxo and hydroxo surface intermediate species were observed on the TiO2 surface, suggesting that the photo-oxidation of water on these anatase TiO2 nanosheets may be initiated by a nucleophilic attack mechanism.

Development of flexible Li-ion batteries for flexible electronics

We provide a critical review on the recent development of flexible lithium-ion batteries(FLIBs)for flexible electronic devices.The innovative designs of cell configuration for bendable and stretchable FLIBs,selection of active materials,and evaluation methods for FLIBs are discussed.The grand challenges for FLIBs are energy density and scale-up fabrication as demonstrated in the review.Furthermore,the lack of quantitative evaluation methods for FLIBs'performance and nondestructive tools to probe the mechanical degradation may significantly hinder the development of FLIB technologies.Perspectives for future research directions,based on the current state of progress,are discussed.

Molecular dynamics for the charging behavior of nanostructured electric double layer capacitors containing room temperature ionic liquids

The charging kinetics of electric double layers （EDLs） is closely related to the performance of a wide variety of nanostructured devices including supercapacitors, electro-actuators, and electrolyte-gated transistors. While room temperature ionic liquids （RTIL） are often used as the charge carrier in these new applications, the theoretical analyses are mostly based on conventional electrokinetic theories suitable for macroscopic electrochemical phenomena in aqueous solutions. In this work, we study the charging behavior of RTIL-EDLs using a coarse-grained molecular model and constant-potential molecular dynamics （MD） simulations. In stark contrast to the predictions of conventional theories, the MD results show oscillatory variations of ionic distributions and electrochemical properties in response to the separation between electrodes. The rate of EDL charging exhibits non-monotonic behavior revealing strong electrostatic correlations in RTIL under confinement.

Curvature effects on electric-double-layer capacitance

Understanding the microscopic structure and thermodynamic properties of electrode/electrolyte interfaces is central to the rational design of electric-double-layer capacitors(EDLCs).Whereas practical applications often entail electrodes with complicated pore structures,theoretical studies are mostly restricted to EDLCs of simple geometry such as planar or slit pores ignoring the curvature effects of the electrode surface.Significant gaps exist regarding the EDLC performance and the interfacial structure.Herein the classical density functional theory(CDFT)is used to study the capacitance and interfacial behavior of spherical electric double layers within a coarse-grained model.The capacitive performance is associated with electrode curvature,surface potential,and electrolyte concentration and can be correlated with a regression-tree(RT)model.The combination of CDFT with machine-learning methods provides a promising quantitative framework useful for the computational screening of porous electrodes and novel electrolytes.

Inverse design of metal-organic frameworks for C_(2)H_(4)/C_(2)H_(6)separation

Efficient separation of C_(2)H_(4)/C_(2)H_(6)mixtures is of paramount importance in the petrochemical industry.Nanoporous materials,especially metal-organic frameworks(MOFs),may serve the purpose owing to their tailorable structures and pore geometries.In this work,we propose a computational framework for high-throughput screening and inverse design of high-performance MOFs for adsorption and membrane processes.High-throughput screening of the computational-ready,experimental(CoRE 2019)MOF database leads to materials with exceptionally high ethane-selective adsorption selectivity(LUDLAZ:7.68)and ethene-selective membrane selectivity(EBINUA02:2167.3).Moreover,the inverse design enables the exploration of broader chemical space and identification of MOF structures with even higher membrane selectivity and permeability.In addition,a relative membrane performance score(rMPS)has been formulated to evaluate the overall membrane performance relative to the Robeson boundary.The computational framework offers guidelines for the design of MOFs and is generically applicable to materials discovery for gas storage and separation.

The potential of plant proteins as antifungal agents for agricultural applications

Fungal pathogens induce a variety of diseases in both plants and post-harvest food crops,resulting in significant crop losses for the agricultural industry.Although the usage of chemical-based fungicides is the most common way to control these diseases,they damage the environment,have the potential to harm human and animal life,and may lead to resistant fungal strains.Accordingly,there is an urgent need for diverse and effective agricultural fungicides that are environmentally-and eco-friendly.Plants have evolved various mechanisms in their innate immune system to defend against fungal pathogens,including soluble proteins secreted from plants with antifungal activities.These proteins can inhibit fungal growth and infection through a variety of mechanisms while exhibiting diverse functionality in addition to antifungal activity.In this mini review,we summarize and discuss the potential of using plant antifungal proteins for future agricultural applications from the perspective of bioengineering and biotechnology.

Enhancing photodynamic inactivation via tunning spatial constraint on photosensitizer

The critical factor of spatial constraint,provided by the external confinement(e.g.,matrix),is often overlooked during photodynamic inactivation,despite playing a crucial role in determining the molecular photophysical process and subsequent antipathogen performance.Here,as a proof-of-concept model,we employed two types of polymers with varying interaction energies with dopants to investigate the intrinsic relationship between spatial constraint and the essential excited-state behaviors of doped photosensitizer(4-(2-(5-(4-(diphenylamino)phenyl)thiophen-2-yl)ethyl)-1-methylquinolin-1-ium iodine,TPP).Through experimental investigation and theoretical calculations,we found that TPP tends to remain in the excited state for a shorter dwell time under weaker spatial constraints due to less restricted molecular motion in polyurethane(PU) nanofibers.Consequently,the singlet oxygen(^(1)O_(2)) generated from doped-TPP shows a 9.23-fold enhancement in PU than in the polyvinylchloride(PVC) matrix.Under light irradiation,the PU@TPP nanofiber can efficiently eliminate the coronavirus MHV-A59(≥99.9997%) at a 220,000-fold higher concentration than the infected space.Its antibacterial efficacy has also been demonstrated,with a killing rate of ≥99%.