Facile, Direct Reaction of Benzaldehydes to 3-Arylprop-2-Enoic Acids and 3-Arylprop-2-Ynoic Acids in Aqueous Medium

Wittig reactions of benzaldehydes, alkanals, and cycloalkanals as well as of acetophenones are carried out with alkoxycarbonyl methylidenetriphenylphosphoranes in 10 w% aqueous NaOH, where the cinnamates and alkenoates produced are hydrolysed in situ and the corresponding acids are obtained after mostly simple extractive work-up, often without employing organic solvents. Under the same conditions, benzaldehydes are reacted with alkoxycarbonyl bromomethy-lidenephosphorane to produce 3-arylprop-2-ynoic acids (arylpropiolic acids).

Ball-milling MoS_2/carbon black hybrid material for catalyzing hydrogen evolution reaction in acidic medium

Replacing platinum for catalyzing hydrogen evolution reaction （HER） in acidic medium remains great chal- lenges. Herein, we prepared few-layered MoS2 by ball milling as an efficient catalyst for HER in acidic medium, The activity of as-prepared MoS2 had a strong dependence on the ball milling time, Furthermore, Ketjen Black EC 300J was added into the ball-milled MoS2 followed by a second ball milling, and the resultant MoS2/carbon black hybrid material showed a much higher HER activity than MoS2 and carbon black alone. The enhanced activity of the MoS2/carbon black hybrid material was attributed to the increased abundance of catalytic edge sites of MoS） and excellent electrical coupling to the underlving carbon network.

Heat and Mass Transfer in MHD Visco-Elastic Fluid Flow through a Porous Medium over a Stretching Sheet with Chemical Reaction

This paper presents the study of convective heat and mass transfer characteristics of an incompressible MHD visco-elastic fluid flow immersed in a porous medium over a stretching sheet with chemical reaction and thermal stratification effects. The resultant governing boundary layer equations are highly non-linear and coupled form of partial differential equations, and they have been solved by using fourth order Runge-Kutta integration scheme with Newton Raphson shooting method. Numerical computations are carried out for the non-dimensional physical parameters. Here a numerical has been carried out to study the effect of different physical parameters such as visco-elasticity, permeability of the porous medium, magnetic field, Grashof number, Schmidt number, heat source parameter and chemical reaction parameter on the flow, heat and mass transfer characteristics.

Mechanism of the Interfacial Reaction of AI_2O_3/Medium Mn Steel Containing Nb

The mechanism of the interfacial reaction of Al_2O_3/medium Mn steel containing Nb was studied by means of the observation on the interfacial reaction phenomenon of Al_2O_3/medium Mn steel,and the analyses on the interracial phases.The results show that when T≥1550℃,the interfacial reac- tion of Al_2O_3/medium Mn steel containing Nb happened.In the medium Mn steel matrix,Nb exists in the form of NbC.NbC are the nucleating base of CO gas bubbles.

MHD Heat and Mass Transfer of an Oscillatory Flow over a Vertical Permeable Plate in a Porous Medium with Chemical Reaction

The problem of magneto-hydro-dynamic (MHD) mass and heat transfer of an oscillatory fluid in two-dimensional viscous, electrically conducting over an infinite vertical permeable moving plate in a saturated porous medium with the presence of a transverse magnetic field and chemical reaction is analytically presented. The governing equations, momentum, energy, and concentration are solved. Various flow parameters effects on velocity, temperature and concentration fields are discussed. It is found that, the fluid velocity increases with increasing both the permeability and chemical reaction parameters. While, it increases with decreasing the magnetic field parameter. Furthermore, the concentration increases with increasing chemical reaction parameters.

镍铁矿热炉中多物理场和还原反应的数值模拟

为了研究36 MW镍铁矿热炉的冶炼过程,建立了一种耦合还原反应的三维瞬态多物理场模型.该模型利用用户自定义函数(UDF)编译了电热转换、电磁感应、磁场扰动和还原反应的输运方程,对炉内物质的流动、质量的转化、热量的传递过程进行模拟,分析了不同时刻多物理场的变化规律和金属氧化物的还原过程.结果表明:交流电弧受电磁和高频电流的影响,出现了明显的趋肤效应和邻近效应;当冶炼时间由10 min增至40 min时,电弧底部最大焦耳热由2.38 MW/m^(3)增至10.32 MW/m^(3),磁场强度最大值由0.00379 T增至0.01397 T;当冶炼40 min时,电弧下方的氧化镍基本被还原,氧化铁被部分还原,氧化铁的质量分数由25.2%降至12.6%,且镍铁氧化物的还原速率随冶炼温度的升高呈非线性增大.

碘对比剂全程化药学服务共识

目的探讨碘对比剂全程化药学服务模式,促进碘对比剂的临床合理使用。方法中国医药教育协会临床合理用药专业委员会和广东省药学会用药评价与临床科研专家委员会组织国内专家,成立《碘对比剂全程化药学服务共识》工作组,针对碘对比剂的发展历程、适应证、禁忌证、不良反应、药物相互作用、特殊人群用药、药学服务等进行文献检索、循证分析和研讨,梳理全程化药学服务的内容与流程,最终形成共识。结果制定的碘对比剂全程化药学服务共识包括检查前对患者、肾功能、合并用药和水化方案的评估,检查中有无发生对比剂外渗或发生(可疑)急性不良反应,检查后的观察时间点和随访等内容,以药学服务流程图展示各阶段的具体工作,并形成用药监护记录表用以记录工作情况。结论本共识构建了碘对比剂全程化药学服务体系,为临床医生、护理人员合理使用该类特殊药品提供了科学依据,也为药师进行相关药学服务提供了参考。

Logistic回归与决策树模型在碘造影剂不良反应预测中的应用

目的采用Logistic回归与决策树模型分析碘造影剂(iodinated contrast medium,ICM)不良反应影响因素。方法不良反应组为2019年1月至2023年8月期间在云南省阜外心血管病医院行CT检查使用ICM并出现不良反应的患者129例,对照组为同期使用ICM未发生不良反应的患者135例,将单因素分析中有统计学意义的变量纳入多因素Logistic回归和决策树模型,提取引起不良反应的影响因素并进行分析。结果Logistic回归结果显示BMI、过敏史和肾功能不全是发生ICM不良反应的影响因素(P<0.05),预测模型为Lggit(P)=0.123×BMI+1.684×过敏史+2.551×肾功能不全-3.652;决策树分析筛选出3个风险变量,包括过敏史、肾功能不全和ICM种类,其中过敏史是最主要的影响因素。结论通过运用Logistic回归和决策树模型预测不良反应的影响因素并将研究转变为了避免不良反应发生的主动预测,对患者安全用药有参考价值。

间充质干细胞治疗皮瓣缺血再灌注损伤的作用机制及优势

背景:间充质干细胞因具有抗氧化、抑制炎症反应和诱导血管新生等作用而被用于皮瓣缺血再灌注损伤中。目的:综述间充质干细胞在治疗皮瓣缺血再灌注损伤方面的作用机制和最新进展,为其进一步理论研究和临床合理应用提供依据。方法:检索CNKI中国期刊全文数据库、万方数据库和PubMed数据库收录的相关文献。中文检索词为“间充质干细胞;皮瓣缺血再灌注损伤;条件培养基;外泌体;氧化应激;炎症反应;血管新生”。英文检索词为“mesenchymal stem cells;flap ischemia reperfusion injury;Conditioned medium;exosomes;Oxidative stress;Inflammatory reaction;Angiogenesis”。检索2010年以来相关文献,通过阅读文章剔除研究内容与文章主题关系不大、质量较差及内容陈旧文献,最终纳入74篇文献进行归纳总结。结果与结论:①间充质干细胞在抗氧化、抑制炎性反应及诱导血管新生等方面作用显著,在治疗皮瓣缺血再灌注损伤中蕴含着巨大潜力。②然而,间充质干细胞自身的缺陷及近年来治疗效果的下降使间充质干细胞的发展和应用陷入了瓶颈期,间充质干细胞条件培养基及其外泌体和间充质干细胞可塑性研究应运而生,且治疗效果明显优于单纯使用间充质干细胞。③因此,更全面地了解间充质干细胞治疗皮瓣缺血再灌注损伤的作用机制和最新治疗进展,对于间充质干细胞的研究和皮瓣缺血再灌注损伤的治疗都具有非常重要的意义。

孔隙—裂缝型岩溶热储热——流—化多场耦合作用机理

岩溶型热储开采过程中,储层孔隙内水岩反应会导致流动通道变形,忽略这一反应过程将导致热储产能预测偏差较大。为了揭示水岩作用下岩溶型热储孔隙和裂缝形态的演化特征,综合考虑了孔隙和裂缝内的水岩反应过程,搭建了孔隙—裂缝双重介质热—流—化多场耦合模型并验证了其准确性,进而分析了热—流—化多物理场与孔隙—裂缝形态的分布特征,探究了孔隙—裂缝内水岩反应对孔、缝变形和系统取热性能的影响。研究结果表明:(1)欠饱和注入条件下,注入井处发生溶解反应,生产30年时,裂缝开度增大了0.32%,孔隙度增大了75.76%;(2)生产30年时,考虑孔隙—裂缝内水岩反应案例的裂缝平均开度降低了0.05%,考虑裂缝而不考虑孔隙内水岩反应案例的裂缝平均开度增大了17.12%,二者呈现相反的变化趋势;(3)考虑孔隙—裂缝内水岩反应案例相比于仅考虑裂缝而不考虑孔隙内水岩反应的案例,生产30年时,生产温度相差不大,系统注采压差增大了1.57倍。结论认为:(1)岩溶型热储孔隙内水岩反应对孔、缝变形和取热性能影响显著,其改变了水岩反应对裂缝开度的作用机理,影响系统注采压差;(2)孔隙内的水岩反应不容忽视,在进行岩溶型热储产能的精确预测和经济评价时必须予以充分考虑;(3)该认识可为岩溶型热储开发方案设计和产能预测方面提供理论和技术参考。

钯催化环加成反应构建中环化合物的研究进展

中环化合物(7—11元环)广泛存在于许多天然产物及药物等功能分子之中,这些分子因具有优异的生物活性及特殊的骨架结构等优点,展现出极其重要的药用价值,如常见的抗癌药物紫杉醇、抗菌药物Spiroxin A等。同时,这类化合物也对化学、医药以及材料等诸多领域产生了深远的影响。但受动力学和热力学因素影响,中环化合物的高效构建依然是一个严峻的挑战。在科研工作者们的不懈努力下,近年来发展出多个新型环加成反应催化体系,其中钯催化环加成反应凭借高效、高选择性和原子经济性等优点在该领域得到了迅猛发展。本文详细介绍了近五年国内外有关钯催化环加成反应构建中环化合物研究的最新进展,旨在为该领域的发展提供一定的帮助。

电针联合中频电治疗对颞颌关节紊乱症患者不良反应及效果的影响

目的探析颞颌关节紊乱症患者应用电针联合中频电治疗所取效果,评估对患者不良反应产生的影响。方法随机选取2022年1月—2023年8月联勤保障部队第九一〇医院收治的60例经临床检查确诊为颞颌关节紊乱症的患者为研究对象,利用随机数表法分为对照组和观察组,各30例。对照组患者应用封闭治疗,观察组应用电针联合中频电治疗仪,对比临床效果,评估指标包含临床治疗有效率、疼痛评分、Helkimo功能障碍指数以及不良反应发生率。结果观察组临床治疗有效率为96.67%,明显高于对照组80.00%,差异有统计学意义(χ^(2)=4.043,P<0.05)。治疗前,两组患者视觉模拟量表(Visual Analogue Scale,VAS)评分比较,差异无统计学意义(P>0.05);治疗后,观察组VAS评分明显低于对照组,差异有统计学意义(P<0.05);观察组Helkimo功能障碍指数测定结果低于对照组,差异有统计学意义(P<0.05)。观察组不良反应发生率(13.33%)低于对照组(23.33%),但差异无统计学意义(χ^(2)=1.002,P>0.05)。结论颞颌关节紊乱症患者应用电针联合中频电治疗具有较高的安全性、有效性,可有效改善患者临床症状,促进功能恢复。

Density Functional Study on the Mechanism of Amadori Rearrangement Reaction

The reaction mechanism of amadori rearrangement in the initial stage of Maillard reaction has been investigated by means of density functional theory calculations in the gaseous phase and aqueous solution.Cyclic ribose and glycine were taken as the model in the amadori rearrangement.Reaction mechanisms have been proposed,and possibility for the formation of different compounds has been evaluated through calculating the relative energy changes for different steps of the reaction by following the total mass balance.The calculations reveal that the amadori rearrangement initialized via the intramolecular rearrangement,transferring one proton from N（3） to O（4） atom.In the next step,the second proton is also transferred from N（3） to O（4） atom,corresponding to the cleavage of C（4）-O（4） bond and the release of one water molecule.Then another proton is transferred from N（3） to C（5） atom via TS3 with the reaction barrier of 58.3 kcal·mol-1 after tunneling the effect correction calculated at the B3LYP/6-31＋G（d） level of theory,and this step is rate limiting for the whole catalytic cycle.Ultimately,the product is generated via keto-enolic tautomerization.Present calculation could provide insights into the reaction mechanism of Maillard reaction since experimental evaluation of the role of intermediates in the Maillard reaction is quite complicated.

Chemical reaction effects on unsteady MHD flow past semi-infinite vertical porous plate with viscous dissipation

The chemical reaction effect on an unsteady magnetohydrodynamic （MHD） flow past a semi-infinite vertical porous plate with viscous dissipation is analyzed. The governing equations of motion, energy, and species are transformed into ordinary differential equations （ODEs） using the time dependent similarity parameter. The resultant ODEs are then solved numerically by a finite element method. The effects of various parameters on the velocity, temperature, and concentration profiles are presented graphically, and the values of the skin-friction, Nusselt number, and Sherwood number for various values of physical parameters are presented through tables.

Structure and Performance of Fe-N_x-C Catalyst for Oxygen Reduction Reaction Prepared by Vacuum Casting Method and the Second Pyrolysis

Affordable non-precious metal（NPM） catalysts played a vital role in the wide application of polymer electrolyte membrane fuel cells（PEMFC）. In current work, a facile vacuum casting reacting method based on vacuum casting was introduced to prepare Fe-N_x-C oxygen reduction reaction（ORR） catalysts with high efficient in acid medium. The catalysts were prepared with ammonium ferrous sulfate hexahydrate（AFS） and 1,10-phenanthroline monohydrate utilizing homemade mesoporous silica template. The heat treatment and its influence on structure and performance were systematically evaluated to achieve superior ORR performance and some clues were found. And 850 ℃ was found to be the best temperature for the first and second pyrolysis. The linear sweep voltammetry（LSV） results showed that there were only 18 mV slightly negative shifts of half-wave potential（E_（1/2）） of the optimal catalyst（749 mV） compared with the commercial Pt/C（20 μg·Pt·cm^-2）. Besides, I850 R also showed better electrochemical stability and methanol-tolerance than that of Pt/C. All evidences proved that our vacuum casting reacting strategy and heat treatment process were prospective for the future R＆D of high performance Fe-N_x-C ORR catalysts.

N/S co-doped 3D carbon framework prepared by a facile morphology-controlled solid-state pyrolysis method for oxygen reduction reaction in both acidic and alkaline media

Developing high-performance non-precious metal electrocatalysts for oxygen reduction reaction(ORR)is crucial for the commercialization of fuel cells and metal-air batteries.However,doped carbon-based materials only show good ORR activity in alkaline medium,and become less effective in acidic environment.We believe that an appropriate combination of both ionic and electronic transport path,and well dopant distribution of doped carbon-based materials would help to realize high ORR performance un-der both acidic and alkaline cond让ions.Accordingly,a nitrogen and sulfur co-doped carbon framework with hierarchical through-hole structure is fabricated by morphology-controlled solid-state pyrolysis of poly(aniline-co-2-ami no thiophenol)foam.The uniform high concentrations of nitrogen and sulfur,high intrinsic conductivity,and integrated three dimensional ionic and electronic transfer passageways of the 3D porous structure lead to synergistic effects in catalyzing ORR.As a result,the limiting current density of the carbonized poly(aniline-co-2-aminothiophenol)foam is equivalent to commercial Pt/C in acidic environment,and twice the latter in alkaline medium.

Influence of Low-Frequency Sonolysis on the Stability of Reactions Involving Associates

The influence of low-frequency sonolysis on the kinetics bimolecular liquid-phase reactions was studied with due regard for the association (dimers and trimers) of starting reagents. The mathematical modeling of chemical reactions that were described by nonlinear differential equations is performed. The steady states, the singular points characteristics, the nature of concentration oscillations in the reaction system are described. With increasing frequency and amplitude of low-frequency sonic waves (up to some critical value), we observed the cessation of the reaction. This observation offers an additional tool for controlling reaction rate by the external action of low-frequency vibrations. The conclusions of the work are obtained under certain assumptions. The exact determination of the critical conditions for changes in dynamics is beyond the scope of the problem.

基于EMMS-1M曳力模型的空气反应器气固流动及化学反应特性数值分析

针对传统曳力模型难以准确预测气固相间曳力的问题,考虑到计算精度和模型通用性,选用经过介尺度修正的EMMS-1M曳力模型耦合双流体模型,模拟了颗粒直径和进口气速对空气反应器冷态流化和热态化学反应的影响。结果表明:颗粒直径减小和进口气速增加,使床层气体压力分布更加均匀,床层轴向颗粒体积分数降低,床层颗粒返混现象减弱,颗粒轴向速度增加,温度升高促进反应正向进行,氧气转化率升高;进口气速增加,使颗粒在床层分布均匀,气固混合彻底,促进了化学反应,但进口气速过高,会携带出大量的颗粒,且在床层的停留时间减少,不利于气固化学反应的发生。

Joule Heating and Thermal Radiation Effects on MHD Boundary Layer Flow of a Nanofluid over an Exponentially Stretching Sheet in a Porous Medium

A numerical study on boundary layer flow behaviour, heat and mass transfer characteristics of a nanofluid over an exponentially stretching sheet in a porous medium is presented in this paper. The sheet is assumed to be permeable. The governing partial differential equations are transformed into coupled nonlinear ordinary differential equations by using suitable similarity transformations. The transformed equations are then solved numerically using the well known explicit finite difference scheme known as the Keller Box method. A detailed parametric study is performed to access the influence of the physical parameters on longitudinal velocity, temperature and nanoparticle volume fraction profiles as well as the local skin-friction coefficient, local Nusselt number and the local Sherwood number and then, the results are presented in both graphical and tabular forms.