Molecular Simulation of CO2/H2 Mixture Separation in Metal-organic Frameworks： Effect of Catenation and Electrostatic Interactions

In this work grand canonical Monte Carlo simulations were performed to study gas separation in three pairs of isoreticular metal-organic frameworks (IRMOFs) with and without catenation at room temperature.Mixture composed of CO2 and H2 was selected as the model system to separate.The results show that CO2 selectivity in catenated MOFs with multi-porous frameworks is much higher than their non-catenated counterparts.The simulations also show that the electrostatic interactions are very important for the selectivity,and the contributions of different electrostatic interactions are different,depending on pore size,pressure and mixture composition.In fact,changing the electrostatic interactions can even qualitatively change the adsorption behavior.A general conclusion is that the electrostatic interactions between adsorbate molecules and the framework atoms play a dominant role at low pressures,and these interactions in catenated MOFs have much more pronounced effects than those in their non-catenated counterparts,while the electrostatic interactions between adsorbate molecules become evident with increasing pressure,and eventually dominant.

Enhancing sintering resistance of atomically dispersed catalysts in reducing environments with organic monolayers

Atomically dispersed precious metal catalysts maximize atom efficiency and exhibit unique reactivity.However,they are susceptible to sintering.Catalytic reactions occurring in reducing environments tend to result in atomically dispersed metals sintering at lower temperatures than in oxidative or inert atmospheres due to the formation of mobile metal-H or metal-CO complexes.Here,we develop a new approach to mitigate sintering of oxide supported atomically dispersed metals in a reducing atmosphere using organophosphonate self-assembled monolayers(SAMs).We demonstrate this for the case of atomically dispersed Rh on Al_(2)O_(3) and TiO_(2) using a combination of CO probe molecule FTIR,temperature programmed desorption,and alkene hydrogenation rate measurements.Evidence suggests that SAM functionalization of the oxide provides physical diffusion barriers for the metal and weakens the interactions between the reducing gas and metal,thereby discouraging the adsorbate-promoted diffusion of metal atoms on oxide supports.Our results show that support functionalization by organic species can provide improved resistance to sintering of atomically dispersed metals with maintained catalytic reactivity.

The Effects of Coil Current Distribution in a Cylindrical Electron Cyclotron Resonance Reactor

Using a 2-D hybrid model,the authors have found that external currents play an important role in the plasma parameters in the reactor.The plasma density,temperature and electrostatic potential would be significantly influenced by the applied external currents.

四配位Ti掺杂有机杂化介孔分子筛的直接合成与表征

以三嵌段共聚物P123为模板剂,NaCl为助剂,1,2-二(三乙氧基甲硅烷基)乙烷为硅源,在水热合成过程中引入钛源,原位一步合成了四配位Ti掺杂在骨架内的SBA-15型有机杂化介孔分子筛(Ti-PMO).利用小角X射线衍射、透射电子显微镜以及低温N2物理吸附等手段表征了Ti-PMO的晶体结构和织构性能,并利用紫外-可见漫反射光谱考察了钛源种类、钛源预水解时间、溶液酸性以及Si/Ti摩尔比对Ti存在形态的影响.研究结果表明,通过精确调控Ti-PMO的合成条件,可使钛源水解产生的低聚中间体与硅源水解产生的低聚中间体充分接触并发生共缩聚,引入的Ti原子能够最终随着水解的氧化硅物种自组装生成有序介孔结构的SBA-15型分子筛,并以四配位形式均匀分布于PMO骨架中.以Cl2TiCp2为钛源,盐酸浓度为0.18mol/L时,钛源预水解6h后加入硅源,在Si/Ti摩尔比大于20时可以得到骨架内四配位Ti掺杂的高度有序介孔结构有机杂化分子筛,其具有良好的热稳定性及水热稳定性.

担载Ir_4原子簇的CO配体与催化性能关系研究

在25～300℃和氦气条件下,制备了具有不同脱羰基程度的[Ir_4(CO)_((11)-x)]^-/MgO(x=1～11)样品,甲苯加氢催化反应的反应速率(TOF)随着脱羰基程度的增加而减小,反应活化能随着脱羰基程度的增加而增大,这些结果表明在Ir_4原子簇上的CO配体促进了甲苯加氢催化反应。

Recent progress in methane dehydroaromatization: From laboratory curiosities to promising technology

Direct conversion of methane to benzene or other valuable chemicals is a very promising process for the efficient application of natural gas. Compared with conversion processes that require oxidants, non-oxidative direct conversion is more attractive due to high selectivity to the target product. In this paper, an alternative route for methane dehydrogenation and selective conversion to benzene and hydrogen without the participation of oxygen is discussed. A brief review of the catalysts used in methane dehydroaromatization （MDA） is first given, followed by our current understanding of the location and the active phase of Mo species, the reaction mechanism, the mechanism of carbonaceous deposit and the deactivation of Mo/zeolite catalysts are systematically discussed. Ways to improve the catalytic activity and stability are described in detail based on catalyst and reaction as well as reactor design. Future prospects for methane dehydroaromatization process are also presented.

Effect of interface on mid-infrared photothermal response of MoS2 thin film grown by pulsed laser deposition

This study reports on the mid-infrared （mid-IR） photothermal response of multilayer MoS2 thin films grown on crystalline （p-type silicon and c-axis- oriented single crystal sapphire） and amorphous （Si/SiO2 and Si/SiN） substrates by pulsed laser deposition （PLD）. The photothermal response of the MoS2 films is measured as the changes in the resistance of the MoS2 films when irradiated with a mid-IR （7 to 8.2 μm） source. We show that enhancing the temperature coefficient of resistance （TCR） of the MoS2 thin films is possible by controlling the film-substrate interface through a proper choice of substrate and growth conditions. The thin films grown by PLD are characterized using X-ray diffraction, Raman, atomic force microscopy, X-ray photoelectron microscopy, and transmission electron microscopy. The high-resolution transmission electron microscopy （HRTEM） images show that the MoS2 films grow on sapphire substrates in a layer-by-layer manner with misfit dislocations. The layer growth morphology is disrupted when the films are grown on substrates with a diamond cubic structure （e.g., silicon） because of twin growth formation. The growth morphology on amorphous substrates, such as Si/SiO2 or Si/SiN, is very different. The PLD-grown MoS2 films on silicon show higher TCR （-2.9% K^-1 at 296 K）, higher mid-IR sensitivity （△R/R = 5.2%）, and higher responsivity （8.7 V·W^-1） compared to both the PLD-grown films on other substrates and the mechanically exfoliated MoS2 flakes transferred to different substrates.

Single-Molecule Kinetics of Nanoparticle Catalysis

Owing to their structural dispersion,the catalytic properties of nanoparticles are challenging to characterize in ensemble-averaged measurements.The single-molecule approach enables studying the catalysis of nanoparticles at the single-particle level with real-time single-turnover resolution.This article reviews our single-molecule fluorescence studies of single Au-nanoparticle catalysis,focusing on the theoretical formulations for extracting quantitative reaction kinetics from the single-turnover resolution catalysis trajectories.We discuss the single-molecule kinetic formulism of the Langmuir-Hinshelwood mechanism for heterogeneous catalysis,as well as of the two-pathway model for product dissociation reactions.This formulism enables the quantitative evaluation of the heterogeneous reactivity and the differential selectivity of individual nanoparticles that are usually hidden in ensemble measurements.Extension of this formulism to single-molecule catalytic kinetics of oligomeric enzymes is also discussed.

An overview of photocatalytic materials

Photocatalysis is an emerging technology that enables a wide variety of applications,including degradation of organics and dyes,antibacterial action,and fuel generation through water splitting and carbon dioxide reduction.Numerous inorganic semiconducting materials have been explored as photocatalysts,and the versatility of these materials and reactions has been expanded in recent years.Understanding the relationship between the physicochemical properties of photocatalytic materials and their performances as well as the fundamentals in catalytic processes is important to design and synthesis of photocatalytic materials.

Multifunctional stimuli responsive polymer-gated iron and gold-embedded silica nano golf balls:Nanoshuttles for targeted on-demand theranostics

Multi-functional nanoshuttles for remotely targeted and on-demand delivery of therapeutic molecules and imaging to defined tissues and organs hold great potentials in personalized medicine, including precise early diagnosis, efficient prevention and therapy without toxicity. Yet, in spite of 25 years of research, there are still no such shuttles available. To this end, we have designed magnetic and gold nanoparticles （NP）-embedded silica nanoshuttles （MGNSs） with nanopores on their surface. Fluorescently labeled Doxombicin （DOX）, a cancer drug, was loaded in the MGNSs as a payload. DOX loaded MGNSs were encapsulated in heat and pH sensitive polymer P（NIPAM-co- MAA） to enable controlled release of the payload. Magnetically-guided transport of MGNSs was examined in： （a） a glass capillary tube to simulate their delivery via blood vessels; and （b） porous hydrogels to simulate their transport in composite human tissues, including bone, cartilage, tendon, muscles and blood-brain barrier {BBB）. The viscoelastic properties of hydrogels were examined by atomic force microscopy （AFM）. Cellular uptake of DOX- loaded MGNSs and the subsequent pH and temperature-mediated release were demonstrated in differentiated human neurons derived from induced pluripotent stem cells （iPSCs） as well as epithelial HeLa cells. The presence of embedded iron and gold NPs in silica shells and polymer-coating are supported by SEM and TEM. Fluorescence spectroscopy and microscopy documented DOX loading in the MGNSs. Time-dependent transport of MGNSs guided by an external magnetic field was observed in both glass capillary tubes and in the porous hydrogel. AFM results affirmed that the stiffness of the hydrogels model the rigidity range from soft tissues to bone. pH and temperature-dependent drug release analysis showed stimuli responsive and gradual drug release. Cells＇ viability MTT assays showed that MGNSs are non-toxic. The cell death from on-demand DOX release was observed in both neurons and epithelial cells even though the drug release efficiency was higher in neurons. Therefore, development of smart nanoshuttles have significant translational potential for controlled delivery of theranostics＇ payloads and precisely guided transport in specified tissues and organs （for example, bone, cartilage, tendon, bone marrow, heart, lung, liver, kidney, and brain） for highly efficient personalized medicine applications.

CONTINUOUS THERMODYNAMICS FOR POLYMER SOLUTIONS Ⅱ.LATTICE-FLUID MODEL

Using lattice-fluid model,a continuous thermodynamic framework is presented forphase-equilibrium calculations for binary solutions with a polydisperse polymer solute.A two-stepprocess is deslgned to form a real polymer solution containing a solvent and a polydisperse polymersolute occupying a volume at fixed temperature and pressure.In the first step,close-packed purecomponents including solvent and polymers with different molar masses or different chain lengths aremixed to form a closed-packed polymer solution.In the second step,the close-packed mixture,con-sidered to be a pseudo-pure substance is mixed with holes to form a real polymer solution with a vol-ume dependent on temperature and pressure.Revised Freed’s model developed previously is adoptedfor both steps.Besides pure-component parameters,a binary size parameter cr and a binary energyparameter ε12 are used.They are all temperature dependent.The discrete-multicomponent approach isadopted to derive expressions for chemical potentials。

CONTINUOUS THERMODYNAMICS FOR POLYMER SOLUTIONS I.CLOSE-PACKED LATTICE MODEL

using close-packed lattice models,a continuous thermodynamic framework is presented forphase-equilibrium calculations for binary solutions with a polydisperse polymer solute.An expressionfor the Helmholtz function of mixing is based on the revised Freed model developed previously.Asize parameter c_r and an energy parameter ε are used;the former can be temperature dependent,while the latter can depend on both temperature and chain-length of the polymer.The discretemulticomponent approach is adopted to derive expressions for chemical potentials,spinodals and criti-cal points.The continuous distribution function is then used in calculations of moments occurring inthose expressions.Computation programs are established for cloud-point-curve,shadow-curve,spinodal and critical-point calculations for polymer solutions with standard distribution or arbitrarydistribution of polymer.In the latter case,the derivative method developed previously is applied.lllustrations for phase-equilibrium calculations are

fficient and universal characterization of atomic structures through a topological graph order parameter

A graph-based order parameter,based on the topology of the graph itself,is introduced for the characterization of atomistic structures.The order parameter is universal to any material/chemical system and is transferable to all structural geometries.Four sets of data are used to validate both the generalizability and accuracy of the algorithm:(1)liquid lithium configurations spanning up to 300 GPa,(2)condensed phases of carbon along with nanotubes and buckyballs at ambient and high temperature,(3)a diverse set of aluminum configurations including surfaces,compressed and expanded lattices,point defects,grain boundaries,liquids,nanoparticles,all at nonzero temperatures,and(4)eleven niobium oxide crystal phases generated with ab initio molecular dynamics.We compare our proposed method to existing,state-of-the-art methods for the cases of aluminum and niobium oxide.Our order parameter uniquely classifies every configuration and outperforms all studied existing methods,opening the door for its use in a multitude of complex application spaces that can require fine structure-level characterization of atomistic graphs.

MoS2-wrapped silicon nanowires for photoelectro- chemical water reduction

铝二硫化物的集成(瞬间 < 潜水艇 class= “ a-plus-plus ” > 2 ) 高度被需要到高表面区域光阴极上为太阳动力的氢进化反应最小化过电位(她的) 。因为他们到 decouple 光吸收和少数搬运人的运输的大电气化学地可得到的表面区域和固有的能力，半导体 nanowires (NW ) 为在 photoelectrochemistry 的使用是有益的。这里，硅(Si ) NW 数组为瞬间作为一个模型光阴极系统被采用 < 潜水艇 class= “ a-plus-plus ” > 2 包装纸，并且他们的太阳开车她的活动被评估。光阴极由组成一明确的瞬间<潜水艇class=“ a-plus-plus ”> 2 /TiO 2 /Si 同轴的 NW heterostructure ，它产出光电流密度依赖 15 妈/厘米<啜class=“ a-plus-plus ”> 2 (在 0 V 对可逆的氢电极( RHE ))与在采用的操作条件下面的好稳定性。这个工作表明地球丰富的 electrocatalysts 结合了电极能提供的高表面区域 NW 比得上为 photocathodic 氢的高贵金属催化剂的性能进化。

Nested Metal Catalysts:Metal Atoms and Clusters Stabilized by Confinement with Accessibility on Supports

Supported catalysts that are important in technology prominently include atomically dispersed metals and metal clusters.When the metals are noble,they are typically unstablesusceptible to sinteringespecially under reducing conditions.Embedding the metals in supports such as organic polymers,metal oxides,and zeolites confers stability on the metals but at the cost of catalytic activity associated with the lack of accessibility of metal bonding sites to reactants.An approach to stabilizing noble metal catalysts while maintaining their accessibility involves anchoring them in molecular-scale nests that are in or on supports.The nests include zeolite pore mouths,zeolite surface cups(half-cages),raft-like islands of oxophilic metals bonded to metal oxide supports,clusters of non-noble metals(e.g.,hosting noble metals as single-atom alloys),and nanoscale metal oxide islands that selectively bond to the catalytic metals,isolating them from the support.These examples illustrate a trend toward precision in the synthesis of solid catalysts,and the latter two classes of nested catalysts offer realistic prospects for economical large-scale application.

介观催化材料的制备、表征和催化性能

研究担载是4个和6个Ir原子簇的催化性能,发现两者有很大的差别,也和常规催化剂有很大的区别。

NANOPARTICLE AEROSOL SCIENCE AND TECHNOLOGY:AN OVERVIEW

As a new scientific discipline, nanoparticle aerosol science and technology （NAST） deals with the formation, properties and behavior of nanoparticles in gases. Driven by its practical applications in many different fields, NAST has been undergoing rapid development. A conceptual framework of the discipline, with its own basic principles, experimental methods and computational techniques, is now taking shape. This paper presents an overview of the current status and research needs of the new discipline. The presentation begins with a discourse on the relationship among various particle systems, which occur frequently in nature and industry. The properties and behavior of nanoparticle aerosols are then discussed, with emphasis on the key roles played by particle size and morphology. Similar to fluid dynamics, NAST is an enabling discipline in the sense that it has provided the concepts and methodology needed for the development of many other fields. Applications of nanoparticle aerosol science and technology are highlighted in three important areas： （1） aerosol processes for synthesis of nanoparticles, （2） atmospheric nanoparticles and global climate, and （3） dosimetry of inhaled nanoparticles. These fields have features in common insofar as nanoparticie aerosols follow the same basic laws of physics and chemistry.

Designing chimeric enzymes inspired by fungal cellulosomes

Cellulosomes are synthesized by anaerobic bacteria and fungi to degrade lignocellulose via synergistic action of multiple enzymes fused to a protein scaffold.Through templating key protein domains(cohesin and dockerin),designer cellulosomes have been engineered from bacterial motifs to alter the activity,stability,and degradation efficiency of enzyme complexes.Recently a parts list for fungal cellulosomes from the anaerobic fungi(Neocallimastigomycota)was determined,which revealed sequence divergent fungal cohesin,dockerin,and scaffoldin domains that could be used to expand the available toolbox to synthesize designer cellulosomes.In this work,multi-domain carbohydrate active enzymes(CAZymes)from 3 cellulosome-producing fungi were analyzed to inform the design of chimeric proteins for synthetic cellulosomes inspired by anaerobic fungi.In particular,Piromyces finnis was used as a structural template for chimeric carbohydrate active enzymes.Recombinant enzymes with retained properties were engineered by combining thermophilic glycosyl hydrolase domains from Thermotoga maritima with dockerin domains from Piromyces finnis.By preserving the protein domain order from P.finnis,chimeric enzymes retained catalytic activity at temperatures over 80°C and were able to associate with cellulosomes purified from anaerobic fungi.Fungal cellulosomes harbor a wide diversity of glycoside hydrolases,each representing templates for the design of chimeric enzymes.By conserving dockerin domain position within the primary structure of each protein,the activity of both the catalytic domain and dockerin domain was retained in enzyme chimeras.Taken further,the domain positioning inferred from native fungal cellulosome proteins can be used to engineer multi-domain proteins with non-native favorable properties,such as thermostability.

Microwave Assisted Hydrothermal Way Towards Highly Crystalized N-Doped Carbon Quantum Dots and Their Oxygen Reduction Performance

We proposed a green microwave-assisted hydrothermal way to synthesize highly crystalized N-doped carbon quantum dots(N-CQDs).The N-CQDs obtained by this microwave method have good crystalline degree(ID/IG=0.6)and a high molar ratio of N/C(11.1%)comparing with those obtained from traditional top-down method.The experimental results show that glycerine plays a key role ill the fonnation of highly crystalized N-CQDs.The as-prepared N-CQDs have good luminescent property and may be utilized as fluorescent probe to detect ions or mark cells.As the majority of N atoms in the N-CQDs were pyridinic type(64.8%),the as-prepared N-CQDs were used as a catalyst for the oxygen reduction reaction(ORR)electrocatalysis in the anode of the fuel cell(the onset potential is-0.121V),which was a 4e-transfer procedure and the catalyst showed good stability after 100 cycles.

Fungal diversity notes 253-366:taxonomic and phylogenetic contributions to fungal taxa

Notes on 113 fungal taxa are compiled in this paper,including 11 new genera,89 new species,one new subspecies,three new combinations and seven reference specimens.Awide geographic and taxonomic range of fungal taxa are detailed.In the Ascomycota the new genera Angustospora(Testudinaceae),Camporesia(Xylariaceae),Clematidis,Crassiparies(Pleosporales genera incertae sedis),Farasanispora,Longiostiolum(Pleosporales genera incertae sedis),Multilocularia(Parabambusicolaceae),Neophaeocryptopus(Dothideaceae),Parameliola(Pleosporales genera incertae sedis),and Towyspora(Lentitheciaceae)are introduced.Newly introduced species are Angustospora nilensis,Aniptodera aquibella,Annulohypoxylon albidiscum,Astrocystis thailandica,Camporesia sambuci,Clematidis italica,Colletotrichum menispermi,C.quinquefoliae,Comoclathris pimpinellae,Crassiparies quadrisporus,Cytospora salicicola,Diatrype thailandica,Dothiorella rhamni,Durotheca macrostroma,Farasanispora avicenniae,Halorosellinia rhizophorae,Humicola koreana,Hypoxylon lilloi,Kirschsteiniothelia tectonae,Lindgomyces okinawaensis,Longiostiolum tectonae,Lophiostoma pseudoarmatisporum,Moelleriella phukhiaoensis,M.pongdueatensis,Mucoharknessia anthoxanthi,Multilocularia bambusae,Multiseptospora thysanolaenae,Neophaeocryptopus cytisi,Ocellularia arachchigei,O.ratnapurensis,Ochronectria thailandica,Ophiocordyceps karstii,Parameliola acaciae,P.dimocarpi,Parastagonospora cumpignensis,Pseudodidymosphaeria phlei,Polyplosphaeria thailandica,Pseudolachnella brevifusiformis,Psiloglonium macrosporum,Rhabdodiscus albodenticulatus,Rosellinia chiangmaiensis,Saccothecium rubi,Seimatosporium pseudocornii,S.pseudorosae,Sigarispora ononidis and Towyspora aestuari.New combinations are provided for Eutiarosporella dactylidis(sexual morph described and illus trated)and Pseudocamarosporium pini.Descriptions,illustrations and/or reference specimens are designated for Aposphaeria corallinolutea,Cryptovalsa ampelina,Dothiorella vidmadera,Ophiocordyceps formosana,Petrakia echinata,Phragmoporthe conformis and Pseudocamarosporium pini.The new species of Basidiomycota are Agaricus coccyginus,A.luteofibrillosus,Amanita atrobrunnea,A.digitosa,A.gleocystidiosa,A.pyriformis,A.strobilipes,Bondarzewia tibetica,Cortinarius albosericeus,C.badioflavidus,C.dentigratus,C.duboisensis,C.fragrantissimus,C.roseobasilis,C.vinaceobrunneus,C.vinaceogrisescens,C.wahkiacus,Cyanoboletus hymenoglutinosus,Fomitiporia atlantica,F.subtilissima,Ganoderma wuzhishanensis,Inonotus shoreicola,Lactifluus armeniacus,L.ramipilosus,Leccinum indoaurantiacum,Musumecia alpina,M.sardoa,Russula amethystina subp.tengii and R.wangii are introduced.Descriptions,illustrations,notes and/or reference specimens are designated for Clarkeinda trachodes,Dentocorticium ussuricum,Galzinia longibasidia,Lentinus stuppeus and Leptocorticium tenellum.The other new genera,species new combinations are Anaeromyces robustus,Neocallimastix californiae and Piromyces finnis from Neocallimastigomycota,Phytophthora estuarina,P.rhizophorae,Salispina,S.intermedia,S.lobata and S.spinosa from Oomycota,and Absidia stercoraria,Gongronella orasabula,Mortierella calciphila,Mucor caatinguensis,M.koreanus,M.merdicola and Rhizopus koreanus in Zygomycota.