A transient model integrating the nanoconfinement effect and pore structure characteristics of oil transport through nanopores

Understanding the integrated transport behavior of oil in shale nanopores is critical to efficient shale oil development. In this paper, based on the time-dependent Poiseuille flow momentum equation, we present a novel transient model to describe oil transport in unsteady and steady states. The model incorporates the effect of the critical shift density, apparent viscosity, slip length, and alkane property, as well as pore tortuosity and surface roughness. We evaluated our model through a comparison with other models, experiments, and molecular dynamics simulations. The results show that the development rates of the volume flows of C_(6)–C_(12) alkane confined in inorganic nanopores and C_(12) alkane confined in organic nanopores were faster than that of the corresponding bulk alkane. In addition, the critical drift density positively promoted the volume flow development rate in the unsteady state and negatively inhibited the mass flow rate in the steady state. This effect was clearest in pores with a smaller radius and lower-energy wall and in alkane with shorter chain lengths. Furthermore, both the nanoconfinement effect and pore structure determined whether the volume flow enhancement rate was greater than or less than 1. The rate increased or decreased with time and was controlled mainly by the nanoconfinement effect. Moreover, as the wall energy increased, the flow inhibition effect increased;as the carbon number of alkane increased, the flow promotion effect increased. The results indicate that the proposed model can accurately describe oil transport in shale nanopores.

水产动物TGF-β超家族基因系统进化及生物学功能研究进展

转化生长因子-β(Transforming growth factor-β,TGF-β)超家族是一类普遍存在于真核生物中的调控型细胞因子,其家族成员众多,按照其序列结构特征和生物学功能的不同,主要分为TGF-β亚家族、DVR(Decapentaplegic/vg-1-related)亚家族、激活素(Activin)/抑制素(Inhibin)亚家族及其他亚家族等。大量研究显示,TGF-β蛋白超家族成员可调控细胞外基质合成、胚胎发育、器官形成、骨骼再生、组织损伤修复、机体免疫及肿瘤发生等多种生理生化过程。近年来,TGF-β超家族成员在调控水产动物细胞分化、胚胎发育、骨骼形成及免疫应答等生理生化过程中的作用受到人们的广泛关注,本文中综述了近年来水产动物TGF-β超家族成员的系统进化及生物学功能研究进展,为全面系统地了解和掌握该家族成员在水产动物繁殖、发育、生理生化及病理响应等过程中的作用提供线索和参考资料。

Development Potentials and Benefit Analysis of Efficient Water-saving Irrigation in Lixin County

On the basis of analyzing water resources,crop planning structure,and irrigation mode in Lixin County,potentials and benefits of developing efficient water-saving irrigation in the county were explored to provide references for its future water-saving irrigation.

Helicobacter pylori inhibits the cleavage of TRAF1 via a Cag A-dependent mechanism

AIM To study the impact on cleavage of tumor necrosis factor receptor-associated factor 1(TRAF1) regulated by Helicobacter pylori(H. pylori).METHODS Cleavage of TRAF1 was detected by western blotting in the human gastric cancer cell line AGS following treatment with an apoptosis inducer. Cleavage of TRAF1 mediated by caspase was examined in vitro using specific caspase inhibitors. The effect of the COOH-terminal TRAF1 fragment on gastric cell apoptosis during H. pylori infection was measured using flow cytometry. The impact of H. pylori infection on TRAF1 cleavage was detected in the presence of apoptosis inducer. The roles of H. pylori virulence factors that may regulate TRAF1 cleavage were analyzed using isogenic cag A-, vac A- and cag E- null mutants.RESULTS TRAF1 was found to be cleaved in AGS cells treated with the apoptosis inducer, and caspase-8 was the major caspase involved in the cleavage of TRAF1. The COOH-terminal TRAF1 fragment significantly induced cell apoptosis(P < 0.05) as well as promoted H. pylori-induced cell apoptosis(P < 0.05). H. pylori infection was found to significantly inhibit the cleavage of TRAF1 and to inhibit the activation of caspase-8 in thepresence of the apoptosis inducer at specific infection times and different cell/bacteria ratios. We also found that the effects of cag E- and cag A- null mutants on the inhibition of TRAF1 cleavage and activation of caspase-8 were significantly attenuated, compared with wild-type H. pylori, in the presence of the apoptosis inducer, showing that the virulence factor Cag A was mainly involved in the inhibition of TRAF1 cleavage.CONCLUSION H. pylori infection significantly inhibits the cleavage of TRAF1 via a CagA-dependent mechanism, which would increase the relative amounts of full-length TRAF1 and exert an antiapoptotic effect on H. pylori-infected cells.

Two-Dimensional Electron Gas with High Mobility Forming at BaO/SrTiO_(3) Interface

Two-dimensional electron gas(2DEG)with high electron mobility is highly desired to study the emergent properties and to enhance future device performance.Here we report the formation of 2DEG with high mobility at the interface between rock-salt Ba O and perovskite Sr Ti O_(3).The interface consists of the ionically compensated Ba O_(1-δ) layer and the electronically compensated Ti O_(2) layer,which is demonstrated as a perfect interface without lattice mismatch.The so-formed interface features metallic conductivity with ultralow square resistance of7.3×10^(-4)Ω/□at 2 K and high residual resistance ratios R_(300 K)/R_(2 K) up to 4200.The electron mobility reaches69000 cm^(2)·V^(-1)·s^(-1)at 2 K,leading to Shubnikov–de Haas oscillations of resistance.Density functional theory calculations reveal that the effective charge transfers from Ba O to the Ti 3d_(xy) orbital occur at the interface,leading to the conducting Ti O_(2) layer.Our work unravels that Ba O can adapt itself by removing oxygen to minimize the lattice mismatch and to provide substantial carriers to Sr Ti O_(3),which is the key to forming 2DEGs with high mobility at the interfaces.

Study on stability of permafrost slopes during thawing

A numerical simulation platform that analyzes the variation of the slope factor of safety with time instantaneously is proposed based on heat conduction theory to study the law of stability development of permafrost slopes during thawing.This platform considers ice-water phase change,elastoplastic constitutive behavior and strength reduction in thawing permafrost and can evaluate the factor of safety of permafrost slopes with different slope angles and water contents.Results indicate that under different slope angles and water contents,the evolution of the factor of safety with time displays two stages:nonlinearly decreasing at first and then essentially remaining constant.During the decreasing stage,the plastic slip line overlaps with the thawing front.In this stage,the selfweight of the post-thawed permafrost layer increases continuously while the shear strength of the frozen-thaw interface keeps unchanged.This is the main reason leading to the decrease in the factor of safety.In the second stage,the thawing depth increases continuously while the position of the plastic slip line remains unchanged,resulting in a constant safety factor stage.

室温克级构筑Cu@CuO及其在法拉第葡萄糖电氧化过程中的动力学提升机制

在临床应用中,一次性条形血糖传感器可以日常监测和维持糖尿病患者的血糖水平,以预防和避免危及生命的并发症.本文采用室温可控原位氧化商业铜的工艺制备了Cu@CuO材料.将具有电催化性能的Cu@CuO丝网印刷到一次性银碳工作电极上,制备了条形无酶葡萄糖传感器.该传感器对葡萄糖的电催化氧化表现出优异的性能:高灵敏度(0.03μA mmol^(-1)L cm^(-2))、低检测限(1.3μmol L^(-1))、宽线性范围(0.0013-2.5 mmol L^(-1))、良好的选择性、重复性(20个电极的相对标准偏差为4.28%),以及在室温下超过3周的稳定性.计算结果表明,铜组分提高了Cu@CuO的导电性和对葡萄糖的吸附能力,从而改善了其在葡萄糖法拉第催化过程中的动力学性能.更重要的是,Cu@CuO的批量制备及其在临床型电极中的应用为其在无酶血糖传感方面的应用提供了一个参考方案.

Fiber orientation effects on grinding characteristics and removal mechanism of 2.5D C_(f)/SiC composites

Carbon fiber reinforced silicon carbide(C_(f)/SiC)composites are widely used in aerospace for their excellent mechanical properties.However,the quality of the machined surface is poor and unpredictable due to the material heterogeneity induced by complex removal mechanism.To clarify the effects of fiber orientation on the grinding characteristics and removal mechanism,single grit scratch experiments under different fiber orientations are conducted and a three-phase numerical modelling method for 2.5D C_(f)/SiC composites is proposed.Three fiber cutting modes i.e.,transverse,normal and longitudinal,are defined by fiber orientation and three machining directions i.e.,MA(longitudinal and normal),MB(longitudinal and transverse)and MC(normal and transverse),are selected to investigate the effect of fiber orientation on grinding force and micro-morphology.Besides,a three-phase cutting model of 2.5D C_(f)/SiC composites considering the mechanical properties of the matrix,fiber and interface is developed.Corresponding simulations are performed to reveal the micro-mechanism of crack initiation and extension as well as the material removal mechanism under different fiber orientations.The results indicate that the scratching forces fluctuate periodically,and the order of mean forces is MA>MC>MB.Cracks tend to grow along the fiber axis,which results in the largest damage layer for transverse fibers and the smallest for longitudinal fibers.The removal modes of transverse fibers are worn,fracture and peel-off,in which normal fibers are pullout and outcrop and the longitudinal fibers are worn and push-off.Under the stable cutting condition,the change of contact area between fiber and grit leads to different removal modes of fiber in the same cutting mode,and the increase of contact area results in the aggravation of fiber fracture.

Association between semen collection time and semen parameters:an observational study

The process of semen collection plays a key role in the quality of semen specimens.However,the association between semen collection time and semen quality is still unclear.In this study,ejaculates by masturbation from 746 subfertile men or healthy men who underwent semen analysis were examined.The median(interquartile range)semen collection time for all participants was 7.0(5.0-11.0)min,and the median time taken for semen collection was lower in healthy men than that in subfertile men(6.0 min vs 7.0 min).An increase in the time required to produce semen samples was associated with poorer semen quality.Among those undergoing assisted reproductive technology(ART),the miscarriage rate was positively correlated with the semen collection time.After adjusting for confounders,the highest quartile(Q4)of collection time was negatively associated with semen volume and sperm concentration.A longer time to produce semen samples(Q3 and Q4)was negatively correlated with progressive and total sperm motility.In addition,there was a significant negative linear association between the semen collection time and the sperm morphology.Higher risks of asthenozoospermia(adjusted odds ratio[OR]=2.06,95%confidence interval[CI]:1.31-3.25,P=0.002)and teratozoospermia(adjusted OR=1.98,95%CI:1.10-3.55,P=0.02)were observed in Q3 than those in Q1.Our results indicate that a higher risk of abnormal semen parameter values was associated with an increase in time for semen collection,which may be related to male fertility through its association with semen quality.

光棘球海胆TGFBR2基因的克隆及其对海水酸化的响应

为了探究光棘球海胆(Mesocentrotus nudus)转化生长因子-βⅡ型受体(Transforming growth factor-βreceptor typeⅡ,TGFBR2)基因的序列信息及其响应海水酸化的模式和规律。本研究利用同源克隆和cDNA末端快速扩增技术(RACE)首次获得光棘球海胆TGFBR2基因(MnTGFBR2)的cDNA全长序列。结果显示:该基因全长为2260 bp,其中5’非编码区长度为227 bp,3’非编码区长度为254 bp,开放阅读框长度为1776 bp,编码一个含592个氨基酸的多肽。MnTGFBR2蛋白理论分子量为66.11 kD,理论等电点为5.30。同源性及系统进化分析显示,Mn TGFBR2蛋白与紫球海胆(Strongylocentrotus purpuratus)TGFBR2蛋白聚为最近的一支,二者序列一致性高达95.97%。实时荧光定量PCR(qRT-PCR)结果显示,MnTGFBR2在管足、围口膜、体腔液、肠和性腺5种组织中均有表达,其相对表达量从高到低依次为:管足>围口膜>体腔液>肠>性腺。海水酸化处理实验发现,随着酸化时间的延长,与自然海水组相比,当海水pH值下降0.3个单位时,光棘球海胆性腺组织和肠组织中MnTGFBR2的相对表达均呈先极显著降低(p<0.01)后升高的趋势;当海水pH值下降0.4个单位时,光棘球海胆性腺组织中MnTGFBR2的相对表达呈先极显著降低(p<0.01)后升高再降低的趋势,而肠组织中MnTGFBR2的相对表达则一直呈现极显著降低趋势(p<0.01);当海水pH值下降0.5个单位时,光棘球海胆性腺组织中MnTGFBR2的相对表达呈先极显著降低(p<0.01)再升高的趋势,而肠组织中MnTGFBR2的相对表达则呈显著降低(p<0.05)的趋势。

Synthesis of Ladder-like Polyphenylsilsesquioxanes with Fairly High Regularity Using 1,2-Ethylenediamine as Endo-template

Ladder-like polyphenylsilsesquioxanes with fairly high regularity were synthesized using an endo-template 1,2-ethylenediamine at mild temperature via direct co-hydrolysis and condensation reactions in the presence of acid catalysts in the mixture of 1,4-dioxane/H2 O. The features for synthesis of ladder-like polyphenylsilsesquioxanes were investigated in detail. The products obtained were characterized by FTIR, SEC, XRD and NMR.

Highly pathogenic coronavirus N protein aggravates inflammation by MASP-2-mediated lectin complement pathway overactivation

Excessive inflammatory responses contribute to the pathogenesis and lethality of highly pathogenic human coronaviruses,but the underlying mechanism remains unclear.In this study,the N proteins of highly pathogenic human coronaviruses,including severe acute respiratory syndrome coronavirus(SARS-CoV),middle east respiratory syndrome coronavirus(MERS-CoV)and severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),were found to bind MASP-2,a key serine protease in the lectin pathway of complement activation,resulting in excessive complement activation by potentiating MBL-dependent MASP-2 activation,and the deposition of MASP-2,C4b,activated C3 and C5b-9.Aggravated inflammatory lung injury was observed in mice infected with adenovirus expressing the N protein.Complement hyperactivation was also observed in SARS-CoV-2-infected patients.Either blocking the N protein:MASP-2 interaction,MASP-2 depletion or suppressing complement activation can significantly alleviate N protein-induced complement hyperactivation and lung injury in vitro and in vivo.Altogether,these data suggested that complement suppression may represent a novel therapeutic approach for pneumonia induced by these highly pathogenic coronaviruses.

Preconditioned gridless methods for solving three-dimensional Euler equations at low Mach numbers

In this paper,preconditioned gridless methods are developed for solving the threedimensional(3D)Euler equations at low Mach numbers.The preconditioned system is obtained by multiplying a preconditioning matrix of the type of Weiss and Smith to the time derivative of the 3D Euler equations,which are discretized under the clouds of points distributed in the computational domain by using a gridless technique.The implementations of the preconditioned gridless methods are mainly based on the frame of the traditional gridless method without preconditioning,which may fail to have convergence for flow simulations at low Mach numbers,therefore the modifications corresponding to the affected terms of preconditioning are mainly addressed in the paper.An explicit four-stage Runge–Kutta scheme is first applied for time integration,and the lower-upper symmetric Gauss-Seidel(LU-SGS)algorithm is then introduced to form the implicit counterpart to have the further speed up of the convergence.Both the resulting explicit and implicit preconditioned gridless methods are validated by simulating flows over two academic bodies like sphere or hemispherical headform,and transonic and nearly incompressible flows over one aerodynamic ONERA M6 wing.The gridless clouds of both regular and irregular points are used in the simulations,which demonstrates the ability of the method presented for coping with flows over complicated aerodynamic geometries.Numerical results of surface pressure distributions agree well with available experimental data or simulated solutions in the literature.The numerical results also show that the preconditioned gridless methods presented still functions for compressible transonic flow simulations and additionally,for nearly incompressible flow simulations at low Mach numbers as well.The convergence of the implicit preconditioned gridless method,as expected,is much faster than its explicit counterpart.

Protection against malaria by immunization with plasmid DNA encoding cholera toxin B subunit and Plasmodium falciparum epitopes

Cholera toxin B subunit is a good carrier protein and an effective adjuvant which can boost both cellular and humoral immunity. DNA fragments encoding B cell, Th cell and CTL epitopes of P. falciparum CS, MSA-1, MSA-2 and RESA antigens were cloned down-stream of cholera toxin B subunit gene in the same reading frame. Another modification using IL2 as adjuvant was also made. High titer of anti-malaria epitopes antibodies and strong cellular immunogenicity were elicited after Balb/c mice were immunized three times with 100 μg recombinant plasmid DNA dissolved in 100 μL PBS. 200 vaccinees were challenged with mouse Plasmodium yoelli to investigate if cross protection existed. The protective efficacy was about 50%. And it is found that the protective efficacy is correlated with CTL activity which was considered to be the primary effects of anti-sporozoite protective immunity. Better results might be expected when the DNA vaccine candidates were applied to primates.

Construction of ternary PEG200-based DESs lubrication systems via tailoring tribo-chemistry

Designing novel lubricants with easily customized structures,devisable compositions,and simple and economic synthesis over traditional lubricants is critical to fulfilling complex applications,prolonging machine lifetime,and saving energy.Deep eutectic solvents(DESs),which show tunable composition,adjustable structure,easy fabrication,and environmental friendliness,are promising candidates for variable and complicated lubricants applications.To promote the use of DESs as lubricants,a series of PEG200-based DESs with active heteroatoms were fabricated to tailor the tribological performance via tribo-chemistry.Thereinto,PEG200/boric acid(BA)DES shows optimal lubrication performance by forming tribo-chemical reaction film composited of B2O3,iron oxides,and FeOOH,and PEG200/thiourea(TU)DES displays abrasive wear-reducing property by producing FeS tribo-chemical film.Given the excellent abrasive wear-resistance of PEG200/TU DES and friction reduction of PEG200/BA DES,ternary PEG200/BA/TU DESs,composited of PEG200/TU DES and PEG200/BA DES,are first exploited.The ternary DESs possess superior wettability and thermal stability,which render them potential lubricants.Tribological tests of the ternary DESs demonstrate that synergistic lubrication is achieved by forming a transfer film consisting of FexBy,BN,B2O3,and FeS.Wherein FexBy,BN,and B2O3 increase load bearing of the film,and FeS mitigates severe abrasive wear.The proposed design philosophy of novel DESs as lubricants opens up a unique realm that is unattainable by traditional DESs lubrication mechanisms and provides a platform to design next-generation DESs lubrication systems.