Structural optimization and performance trade-off strategies for semi-crystalline sulfonated poly(arylene ether ketone) membranes in high-concentration direct methanol fuel cells

Direct methanol fuel cells(DMFCs) have attracted extensive attention as promising next-generation energy conversion devices. However, commercialized proton exchange membranes(PEMs) hardly fulfill the demand of methanol tolerance for DMFCs employing high-concentration methanol solutions.Herein, we report a series of semi-crystalline poly(arylene ether ketone) PEMs with ultra-densely sulfonic-acid-functionalized pendants linked by flexible alkyl chains, namely, SL-SPEK-x(where x represents the molar ratio of the novel monomer containing multiple phenyl side chain to the bisfluoride monomers). The delicate structural design rendered SL-SPEK-x membranes with high crystallinity and well-defined nanoscale phase separation between hydrophilic and hydrophobic phases. The reinforcement from poly(ether ketone) crystals enabled membranes with inhibited dimensional variation and methanol penetration. Furthermore, microphase separation significantly enhanced proton conductivity. The SL-SPEK-12.5 membrane achieved the optimum trade-off between proton conductivity(0.182 S cm^(-1), 80 ℃), water swelling(13.6%, 80 ℃), and methanol permeability(1.6 × 10^(-7)cm~2 s^(-1)). The DMFC assembled by the SL-SPEK-12.5 membrane operated smoothly with a 10 M methanol solution, outputting a maximum power density of 158.3 mW cm^(-2), nearly twice that of Nafion 117(94.2 mW cm^(-2)). Overall, the novel structural optimization strategy provides the possibility of PEMs surviving in high-concentration methanol solutions, thus facilitating the miniaturization and portability of DMFC devices.

Preparation of ZIF-8@PEBAX/PVDF nanocomposite membrane by the combination of self-assembly and in-situ growth for removing thiophene from the model gasoline

Metal-organic frameworks(MOFs)have gained attention in the development of MOFs/polymer hybrid membranes for pervaporation.However,the agglomeration of MOFs particles and interfacial defects limit its further application.In this study,we present a novel approach to fabricate a ZIF-8@PEBAX/PVDF nanocomposite membrane for removing thiophene from the model gasoline by combination of selfassembly and in-situ growth.Firstly,a PVDF supporting membrane was modified to have a negative charge.Next,positively charged zinc ions were attracted onto the negatively charged PVDF supporting membrane through electrostatic interaction.Afterwards,the Zinc ions deposited PVDF membrane was immersed into dimethylimidazole solution to form a uniform ZIF-8 layer.Finally,the ZIF-8 layer was coated with poly(ether-block-amide)(PEBAX)using the pouring method.Experimental results showed that the separating efficiency of the ZIF-8@PEBAX/PVDF nanocomposite membrane was improved significantly compared to that of pristine PEBAX membrane.The optimal permeation flux and enrichment factor of membrane were 27.80 kg(m^(2)h)^(-1)and 6.9,respectively.

Amino-functionalized UiO-66-doped mixed matrix membranes with high permeation performance and fouling resistance

For the reduction of bovine serum proteins from wastewater,a novel mixed matrix membrane was prepared by functionalizing the substrate material polyaryletherketone(PAEK),followed by carboxyl groups(C-SPAEKS),and then adding amino-functionalized UiO-66-NH_(2)(Am-UiO-66-NH_(2)).Aminofunctionalization of UiO-66 was accomplished by melamine,followed by an amidation reaction to immobilize Am-UiO-66-NH_(2),which was immobilized on the surface of the membrane as well as in the pore channels,which enhanced the hydrophilicity of the membrane surface while increasing the negative potential of the membrane surface.This nanoparticle-loaded ultrafiltration membrane has good permeation performance,with a pure water flux of up to 482.3 L·m^(-2)·h^(-1) for C-SPAEKS/AmUiO-66-NH_(2) and a retention rate of up to 98.7%for bovine serum albumin(BSA)-contaminated solutions.Meanwhile,after several hydrophilic modifications,the flux recovery of BSA contaminants by this series of membranes increased from 56.2%to 80.55%of pure membranes.The results of ultra-filtration flux time tests performed at room temperature showed that the series of ultrafiltration membranes remained relatively stable over a test time of 300 min.Thus,the newly developed mixed matrix membrane showed potential for high efficiency and stability in wastewater treatment containing bovine serum proteins.

Effects of Topographical and Edaphic Factors on the Distribution of Plant Communities in two Subtropical Karst Forests,Southwestern China

Relationships between topography,soil properties and the distribution of plant communities on two different rocky hillsides are examined in two subtropical karst forests in the Maolan National Natural Reserve,southwestern China.Surveys of two 1-ha permanent plots at each forest,and measurements of four topographic and thirteen edaphic factors on the slopes were performed.Twoway Indicator Species Analysis(TWINSPAN) and Detrended Canonical Correspondence Analysis(DCCA) were used for the classification of plant communities and for vegetation ordination with environmental variables.One hundred 10m×10m quadrats in each plot were classified into four plant community types.A clear altitudinal gradient suggested that elevation was important in community differentiation.The topography and soil explained 51.06% and 54.69% of the variability of the distribution of plant species in the two forest plots,respectively,indicating both topographic factors(eg.elevation,slope and rock-bareness rate) and edaphic factors(e.g.total P,K and exchangeable Ca) were the important drivers of the distribution of woody plant species in subtropical karst forest.However,our results suggested that topographical factors were more important than edaphic ones in affecting local plant distribution on steep slopes with extensive rock outcrops,while edaphic factors were more influential on gentle slope and relatively thick soil over rock in subtropical karst forest.Understanding relationships between vegetation and environmental factors in karst forest ecosystems would enable us to apply these findings in vegetation management strategies and restoration of forest communities.

Biodistribution and Toxicity Assessment of Superparamagnetic Iron Oxide Nanoparticles In Vitro and In Vivo

Biodistribution and toxicity assessment are critical for safe clinical use of newly developed medicines.Superparamagnetic iron oxide nanoparticles (SPION)are effective carriers for targeted drug delivery.This study aimed to examine the toxicity and biodistribution of SPION coated with polyethylenimine (PEI)(SPION-PEI)designed for small interfering RNA (siRNA) delivery both in vitro and in vivo.SPION-PEI/siRNA complexes were prepared at different weight ratios.Cytotoxic effects of SPION-PEI/siRNA on HSC-T6 cell viability were determined by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT).Rats were divided into three groups:a control group,a normal-saline group and a SPION-PEI/siRNA group.After a single intravenous injection,in vivo nanoparticle biodistribution and accumulation were evaluated by Prussian blue staining in the heart,liver,spleen,lung and kidney 8 h,24 h,and 7 days after the injection.Their distribution was histologically studied at the three time points by measuring ironpositive areas (μm2)in organ sections stained with Prussian blue.The same organs were analyzed by H&E staining for any possible histopathological changes.Furthermore,biochemical indexes such as alanine amino transaminase (ALT),aspartate transaminase (AST),blood urea nitrogen (BUN)and creatinine (CREA)were also assessed at all experimental time points.Electrophoresis exhibited that the SPION-PEI could retard siRNA altogether at weight ratios above 4.MTT assay showed that SPION-PEI loaded with siRNA had low cytotoxicity.In vivo study revealed that the liver and spleen were the major sites of SPION-PEI/siRNA deposition.The iron content was significantly increased in the liver and spleen,peaking 24 h after intravenous injection and then declining gradually.No evidence was found of irreversible histopathological damage to any of the organs tested.These results suggested that most SPION-PEI/siRNA complexes were distributed in the liver and spleen,which might be the target organs of SPION-PEI/siRNA complexes.SPION- PEI/siRNA may serve as in vivo carrier for biomedical medicines.

Effect of cobalt loading on reducibility, dispersion and crystallite size of Co/Al_2O_3 Fischer-Tropsch catalyst

Co/Al2O3 Fischer-Tropsch synthesis catalysts with different cobalt loadings were prepared using incipient wetness impregnation method. The effects of cobalt loading on the properties of catalysts were studied by means of X-ray diffraction （XRD）, temperature programmed reduction （TPR）, hydrogen temperature programmed desorption （H2-TPD） and O2 titration. Co-support compound formation can be detected in catalyst system by XRD. For the Co/Al2O3 catalysts with low cobalt loading, CoAl2O4 phase appears visibly. Two different reduction regions can be presented for Co/Al2O3 catalysts, which belong to Co3O4 crystallites （reduction at 320 ℃） and cobalt oxide-alumina interaction species （reduction at above 400 ℃）. Increasing Co loading results in the increase of Co3O4 crystallite size. The reduced Co/Al2O3 catalysts have two adsorption sites, and cobalt loading greatly influences the adsorption behavior. With the increase of cobalt loading, the amount of low temperature adsorption is increased, the amount of high temperature adsorption is decreased, and the percentage reduction and cobalt crystallite size are increased.

Seasonal and population differences in migration of Whimbrels in the East Asian–Australasian Flyway

Background:Conserving migratory birds is challenging due to their reliance on multiple distant sites at different stages of their annual life cycle.The concept of“flyway”,which refers to all areas covered by the breeding,nonbreeding,and migrating of birds,provides a framework for international cooperation for conservation.In the same flyway,however,the migratory activities of the same species can differ substantially between seasons and populations.Clarifying the seasonal and population differences in migration is helpful for understanding migration ecology and for identifying conservation gaps.Methods:Using satellite‑tracking we tracked the migration of Whimbrels(Numenius phaeopus variegatus)from nonbreeding sites at Moreton Bay(MB)and Roebuck Bay(RB)in Australia in the East Asian-Australasian Flyway.Mantel tests were used to analyze the strength of migration connectivity between the nonbreeding and breeding sites of MB and RB populations.Welch’s t test was used to compare the migration activities between the two populations and between northward and southward migration.Results:During northward migration,migration distance and duration were longer for the MB population than for the RB population.The distance and duration of the first leg flight during northward migration were longer for the MB population than for the RB population,suggesting that MB individuals deposited more fuel before departing from nonbreeding sites to support their longer nonstop flight.The RB population exhibited weaker migration connectivity(breeding sites dispersing over a range of 60 longitudes)than the MB population(breeding sites concentrating in a range of 5 longitudes in Far Eastern Russia).Compared with MB population,RB population was more dependent on the stopover sites in the Yellow Sea and the coastal regions in China,where tidal habitat has suffered dramatic loss.However,RB population increased while MB population decreased over the past decades,suggesting that loss of tidal habitat at stopover sites had less impact on the Whimbrel populations,which can use diverse habitat types.Different trends between the populations might be due to the different degrees of hunting pressure in their breeding grounds.Conclusions:This study highlights that conservation measures can be improved by understanding the full annual life cycle of movements of multiple populations of Whimbrels and probably other migratory birds.

Application of network pharmacology in the prevention and treatment of COVID-19 by traditional Chinese medicine

Network pharmacology is an emerging technology based on systems biology and computer information technology,with the help of databases and related auxiliary software,to carry out new drug development and the screening analysis of drug active ingredients and targets.At present,the network pharmacology has been used widely in the research of prevention and treatment drugs for coronavirus disease 2019(COVID-19).This paper reviews the research methods of network pharmacology in the field of prevention and treatment of COVID-19 by traditional Chinese medicine(TCM)and the development of its specific drugs and further explores the concrete application ideas of this technology.The necessary databases and tools of necessary for screening the active components and targets to molecular docking are summarized.In addition,the practical application of network pharmacology in the study of several potential TCM and active components against COVID-19 is reviewed,mainly including the screening of active components,the discovery of target,and the elucidation of action mechanism.The diversification of research ideas of network pharmacology in the field of TCM was realized,in particular,with two specific ideas in the study of active ingredients of TCM.Finally,the difference of control effect among several TCM and Western medicines on COVID-19 and the limitation and challenge of network pharmacology in TCM,i.e.,the insufficient integrity and accuracy of the database,the uncertain complexity of components analysis,the unclear mechanism of component-target action,and some new challenges due to the characteristics of TCM,are discussed.In view of the importance of TCM in the field of control of COVID-19,the combination of TCM and network pharmacology will continue to play an important role in the development of specific drugs of COVID-19 in the future,in particular,to save time and reduce the workload of drug developers,which is also a direction of TCM development.This study provides theoretical reference and methodological basis for the prevention and treatment of COVID-19 by TCM.

PREPARATION AND CHARACTERIZATION OF DOXORUBICIN-LOADED MAGNETIC ANTICANCER NANOPARTICLES

Doxorubicin(ADM)-loaded magnetic anticancer nanoparticles,using Fe3O4 as core, doxorubicin as model drug and polyvinylpyrrolidone (PVP) as matrix, were prepared by inverse emulsion polymerization. The experimental results showed that the average diameter of Fe3O4 particles was 19.8nm. The X-ray diffraction indicated that the prepared Fe3O4 particle was pure cubic Fe3O4. The results obtained by SEM showed the magnetic nanoparticles under optimal operating condition had a smooth spherical surface , LLS showed an average size of 78.7nm. And IR results demonstrated that they consisted of ADM, PVP and Fe3O4.

Modulating the p-band center of carbon nanofibers derived from Co spin state as anode for high-power sodium storage

Carbon nanofibers(CNFs)have received extensive and in-depth studied as anodes for sodium-ion batteries(SIBs),and yet their initial Coulombic efficiency and rate capability remain enormous challenge at practical level.Herein,CNFs anchored with cobalt nanocluster(CNFs-Co)were prepared using chemical vapor deposition and thermal reduction methods.The as-prepared CNFs-Co shows a high initial Coulombic efficiency of 91%and a high specific discharge capacity of 246 mAh/g at 0.1 A/g after 200 cycles as anode for SIBs.Meanwhile,the CNFs-Co anode still delivers a high cycling stability with 108 mAh/g after 1000 cycles at 10 A/g.These excellent electrochemical properties could be attributed to the involved spin state Co,which endows CNFs with large interplanar spacing(0.39 nm)and abundant vacancy defects.Importantly,the spin state Co downshifts the p-band center of carbon and strengthens the Na+adsorption energy from-2.33 eV to-2.64 eV based on density functional theory calculation.This novel strategy of modulating the carbon electronic structure by the spin state of magnetic metals provides a reference for the development of high-performance carbon-based anode materials.

Metallaphotoredox-Catalyzed Three-Component Couplings for Practical Synthesis of Ureas and Carbamates

Ureas are widely used in drugs,materials and catalysts because of their diamide structure,which can form strong hydrogen bonds.Therefore,it is of great scientific significance to develop efficient and green methods for the synthesis of urea compounds,especially unsymmetrical ureas.Here,we have disclosed novel and highly efficient three-component coupling reactions of organic halides,sodium cyanate and amines enabled by nickel/photoredox dual catalysis for the preparation of unsymmetrical ureas.The reaction features simple and safe operations,broad substrate scopes,and product diversities.It allows the facile synthesis of N-aryl/vinyl ureas from readily available,user-friendly feedstocks under mild conditions(27 examples,36%—98%yields).In addition,this method is further derived to alcohols as nucleophiles to synthesize a series of carbamates(15 examples,40%—95%yields).The mechanism experiment shows that the isocyanate produced by the coupling of halide and sodium cyanate may be the key intermediate in this reaction.

A New Species of the Genus Trimeresurus from Southwest China(Squamata:Viperidae)

Species from the Trimeresurus popeiorum complex(Subgenus: Popeia) is a very complex group. T. popeiorum is the only Popeia species known from China. During the past two years, five adult Popeia specimens(4 males, 1 female) were collected from Yingjiang County, Southern Yunnan, China. Molecular, morphological and ecological data show distinct differences from known species, herein we describe these specimens as a new species Trimeresurus yingjiangensis sp. nov Chen, Ding, Shi and Zhang, 2018. Morphologically, the new species distinct from other Popeia species by a combination of following characters:(1) dorsal body olive drab,without cross bands on the scales;(2) a conspicuous bicolor ventrolateral stripe present on each side of males, first row of dorsal scales firebrick with a white ellipse dot on posterior upper part in male, these strips absent in females;(3) eyes firebrick in both gender;(4) suboculars separated from 3rd upper labial by one scale on each side;(5) ventrals 164–168(n = 5);(6) MSR 21.

An Improved Approach for Rapidly Identifying Different Types of Gram-Negative Bacterial Secreted Proteins

Protein secretion plays an important role in bacterial lifestyles. In Gram-negative bacteria, a wide range of proteins are secreted to modulate the interactions of bacteria with their environments and other bacteria via various secretion systems. These proteins are essential for the virulence of bacteria, so it is crucial to study them for the pathogenesis of diseases and the development of drugs. Using amino acid composition (AAC), position-specific scoring matrix (PSSM) and N-terminal signal peptides, two different substitution models are firstly constructed to transform protein sequences into numerical vectors. Then, based on support vector machine (SVM) and the “one to one”?algorithm, a hybrid multi-classifier named SecretP v.2.2 is proposed to rapidly and accurately?distinguish different types of Gram-negative?bacterial secreted proteins. When performed on the same test set for a comparison with other methods, SecretP v.2.2 gets the highest total sensitivity of 93.60%. A public independent dataset is used to further test the power of SecretP v.2.2 for predicting NCSPs, it also yields satisfactory results.

Ten new aurovertins from cultures of the basidiomycete Albatrellus confluens

Aurovertins J-S(1-10),together with four known metabolites,aurovertins B,C,E,and I(11-14),were isolated from cultures of the basidiomycete Albatrellus confluens.The structures of compounds 1-10 were elucidated on the basis of extensive spectroscopic analysis.All compounds were evaluated for their cytotoxic activities on five tumor cell lines.

Theoretical Calculation about the High Energy Density Molecules of Nitrate Ester Substitution Derivatives of Prismane

The nitrate ester substitution derivatives of prismane were studied at the B3LYP/6-311G＊＊ level. The sublimation enthalpies and heats of formation in gas phase and solid state were calculated. The detonation performances were also predicted by using the famous Kamlet-Jacbos equation. Our calculated results show that introducing nitrate ester group into prismane is helpful to enhance its detonation properties. Stabilities were evaluated through the bond dissociation energies, bond order, characteristic heights（H50） and band gap calculations. The trigger bonds in the pyrolysis process of prismane derivatives were confirmed as O–ON2 bond. The BDEs of all compounds were large, so these prismane derivatives have excellent stability consistent with the results of H50 and band gap.

A New Europium Coordination Compound Supported by 4,6-Dibenzoylisophthalic Acid Ligands

A unique metal-organic framework（MOF） [Eu_2（L）_3（phen）_2]_n（1, H_2L = 4,6-dibenzoylisophthalic acid, phen = 1,10-phenanthroline） has been synthesized under hydrothermal conditions and characterized by single-crystal X-ray analysis, elemental analyses, powder X-ray diffraction, TGA measurement as well as IR spectra. The crystal is of triclinic system, space group P1, C_（90）H_（52）Eu_2N_4O_（18）, M_r = 1781.32, a = 9.8697（4）, b = 16.7466（6）, c = 22.2556（10） A, α = 87.113（3）, β = 77.575（5）, γ = 89.458（3）°, V = 3587.8（3） A^3, Z = 2, D_c = 1.649 g/cm^3, F（000） = 1780, μ（MoKα） = 1.813 mm^（-1）, Rint = 0.0181, R = 0.0260 and wR = 0.0592 for 14000 observed reflections with I 〉 2σ（I）. X-ray analysis shows that the title compound exhibits a 2D layer structure linked by L ligands with two coordination modes and two distinguished conformations, and further linked into a 3D supramolecular architecture through C-H···O weak interactions between hydrogen of phen phenyl ring and the carboxylate oxygen atom of adjacent sheets. In addition, the luminescence property of 1 was investigated.

A New 3D Metal-organic Framework with Tetranuclear Cadmium(II) Clusters: Synthesis, Structure, and Luminescent Property

A unique metal-organic framework [Cd2（L）1.5（μ3-OH）（H2 O）2 ]·2H2 O（1, H2 L = 2,5-dibenzoylterephthalic acid） has been synthesized under hydrothermal conditions, and characterized by single-crystal X-ray diffractions, elemental analyses, IR spectra and fluorescence spectrum. The compound is of triclinic system, space group P1, C33 H27 CdO14, Mr = 870.33, a = 12.2939（17）, b = 12.5135（9）, c = 13.2046（10）, α = 115.3190（10）, β = 96.9140（10）, γ = 109.7950（10）°, V = 1641.6（3）3, Z = 2, Dc = 1.761 g/cm3, F（000） = 862, μ（MoK） = 1.366 mm-1, Rint = 0.0148, R = 0.0240 and wR = 0.0639 for 5995 observed reflections with I 〉 2σ（I）. X-ray analysis shows that the title complex exhibits a 3D framework with（412·63） topology, in which the tetra-nuclear [Cd4（μ3-OH）2 ] clusters act as 6-connected nodes, and the L ligands can be simplified to be linear connectors. Moreover, the thermal stability and fluorescence have been studied in detail.

Liquid Chromatography-Electrospray Ionization Mass Spectrometry Method for Determination of Protopanaxadiol in Rat Plasma

A simple, rapid and sensitive method for the determination of protopanaxadiol in rat plasma with ginsenoside Rh2 as internal standard was developed and validated. The analyte and internal standard were extracted from plasma with ether-dichloromethane（3：2, volume ratio） and then were analyzed by reversed-phase HPLC on a short Zorbax Extend C18 column（50 mm×2.1 mm, 3.5 μm i. d.） eluted with a mobile phase consisting of acetonitrile/methanol 0.10 mmol/L ammonium acetate（45：45：10, volume ratio） at 0.4 mL/min. Detection was performed on an Applied Biosystems Sciex API 4000 mass spectrometer set at unit resolution in the multiple reaction monitoring mode. Electrospray ionization was used for ion production. The assay method shows linear over a range of 5-2000 ng/mL and intra- and inter-day precisions over this range were 〈10.0% with accuracy ranged from 86.3% to 114.1%. The limit of detection was 500 pg/mL in the plasma. The method was successfully applied to a preclinical pharmacokinetic study of protopanaxadiol（17.5 mg/kg） administered as a single oral dose.

Effects of Cadmium Stress on the Quality of Rice Seeds

Germination and hydroponic experiments are performed on rice seeds growing in soils treated with Cd stress,with rice seeds of the same variety that is not treated with Cd stress as a control,to study the effects of Cd stress on quality of rice seeds.The results have shown that:(1)Cd stress reduces the thousand grain weight of rice seeds,and higher Cd content means lower thousand grain weight;(2)The germination vigor and germination percentage of rice seeds under Cd stress as well as theirα-amylase activity andβ-amylase activity are all lower than those of the control.They decreases as the Cd stress increases;(3)For rice seeds under Cd stress,the height,fresh and dry weight of seedlings,as well as the chlorophyll content,photosynthetic rate and content of soluble protein of their leaves are all lower than those of the control.This indicates that Cd stress has certain effects on the germination and growth of the rice seeds.