房地产开发应与城市规划协调发展

分析我国房地产开发过程中存在的问题,阐述了协调城市规划与房地产开发的原则和措施.     

Morphology‐dependent electrocatalytic activity of nanostructured Pt/C particles from hybrid aerosol–colloid process

An optimum nanostructure and pore size of catalyst supports is very important in achieving high catalytic performances. In this instance, we evaluated the effects of various carbon nanostructures on the catalytic performances of carbon‐supported platinum (Pt/C) electrocatalysts experimentally and numerically. The Pt/C catalysts were prepared using a hybrid method involving the preparation of dense, hollow, and porous nanostructured carbon particle via aerosol spray pyrolysis followed by microwave‐assisted Pt deposition. Electrochemical characterization of the catalysts showed that the porous Pt/C catalyst gave the best performance; its electrochemical surface area was much higher, more than twice than those of hollow or dense Pt/C. The effects of pore size on electrocatalysis were also studied. The results showed the importance of a balance between mesopores and macropores for effective catalysis with a high charge transfer rate. A fluid flow model showed that good oxygen transport contributed to the catalytic activity. © 2015 American Institute of Chemical Engineers AIChE J, 62: 440–450, 2016     

Temperature gradients drive radial fluid flow in petri dishes and multiwell plates

Liquid in a Petri dish spontaneously circulates in a radial pattern, even when the dish is at rest. These fluid flows have been observed and utilized for biological research, but their origins have not been well‐studied. Here, particle‐tracking to measure velocities of radial fluid flows, which are shown to be linked to evaporation, is used. Infrared thermal imaging was used to identify thermal gradients at the air‐liquid interface and at the bottom of the dish. Two‐color ratiometric fluorescence confocal imaging was used to measure thermal gradients in the vertical direction within the fluid. A finite‐element model of the fluid, incorporating the measured temperature profiles, shows that buoyancy forces are sufficient to produce flows consistent with the measured particle velocity results. Such flows may arise in other dish or plate formats, and may impact biological research in positive or negative ways. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2227–2233, 2016     

质子交换膜燃料电池内电荷传递的数值模拟

为深入研究质子交换膜燃料电池内电荷传递的规律,发展了一个三维的单相流、非等温数学模型,模型考虑了电子在催化层和扩散层、质子在催化层和质子交换膜中的传递。通过计算得到了电池内电位和电流密度的空间分布,分析了不同电极结构参数下电流密度的分布和最终造成的性能差异。结果表明,欧姆电位的下降主要发生在膜相电位,而碳相电位的下降几乎可以忽略不计;电流密度在流道与集电极交界处出现＂火焰形＂累积效应;改变电池的结构对电池性能影响不大,应结合加工成本和电流密度分布综合考虑。     

对我省水路客运发展的分析

正确估计和评价陕西水路客运在综合运输网中的地位和作用，是制定陕西船运发展远景目标的客观要求。本文对陕西水路客运的现状及其特点进行了分析和评价，在此基础上，就解决陕西水路客运今后发展方向、发展措施等方面的问题提出了建议。     

Internal Mass Transfer during Isothermal Drying of a Porous Solid Containing Multicomponent Liquid Mixtures

Abstract

Internal mass transfer in a porous solid partially saturated with multicomponent liquids has been experimentally and theoretically studied. Isothermal drying experiments were performed using a jacketed wind tunnel where the transient composition profiles and total liquid content of a cylindrical sample were determined. Sand samples wetted with the ternary liquid mixtures water-methanol-ethanol and 2-propanol-methanol-ethanol were dried at two different initial compositions and temperatures. A mathematical model including mass transfer by capillary movement of the liquid and interactive diffusion in both gas and liquid phase was developed. To simulate the capillary movement of liquid mixtures, parameters experimentally determined for single liquids where weighed according to liquid composition. A fairly good agreement between theoretical and experimental liquid composition profiles was obtained provided that axial dispersion is included in the model.     

Theoretical study of electron transport properties of SimCn /Cn clusters tethered on graphene nanoribbon

Electron transport properties of optimized typical Si_mC_n/C_n clusters, including Si₄C, Si₈C₅, Si₉C₆, C₆, C₁₂ and C₁₃, connected to zigzag graphene nanoribbon (ZGNR) electrodes are theoretically studied through first-principles density functional theory (DFT). As for Si₄C, Si₈C₅, Si₉C₆ clusters, the transmission values at the fermi level show a decreasing tendency with the increase in the number of carbon and silicon atoms. Interestingly, Si₉C₆ cluster with ring structure (C₆) has poor electron transport properties in spite of C₆ showing good electron transport properties. Although C₁₂ cluster shows smaller transmission values at the fermi level, when adding an atom to it, - C₁₃ shows excellent electron transport properties. The electrode coupling of ZGNR-C₁₂ is the strongest compared with ZGNR-C₆ and ZGNR-C₁₃ because it forms sp³ orbital which has stronger bond. Our findings may pave a new path for the exploration of nano electronics.     

Crown ether-thiourea conjugates as ion transporters

Na⁺,Cl^?and K⁺are the most abundant electrolytes present in biological fluids that are essential to the regulation of pH homeostasis,membrane potential and cell volume in living organisms.Herein,we report synthetic crown ether-thiourea conjugates as a cation/anion symporter,which can transport both Na+and Cl^–across lipid bilayers with relatively high transport activity.Surprisingly,the ion transport activities were diminished when high concentrations of K+ions were present outside the vesicles.This unusual behavior resulted from the strong affinity of the transporters for K⁺ions,which led to predominant partitioning of the transporters as the K⁺complexes in the aqueous phase preventing the transporter incorporation into the membrane.Synthetic membrane transporters with Na⁺,Cl^?and K⁺transport capabilities may have potential biological and medicinal applications.     

THE EFFECT OF TEMPERATURE TREATMENT ON PENETRANT TRANSPORT IN COAL

The macromolecular structure of coals thermally treated at 35^°C, 100^°C and 150^°C was investigated by dynamic penetrant transport in thin coal sections. The effects of temperature, carbon content in coal, and penetrant type on the transport mechanism were investigated. Dynamic swelling studies showed that penetrant transport into coal is a function of the average molecular weight between crosslinks, M_c. The penetrant transport mechanism at low activity is Fickian diffusion. The transport mechanism deviates from Fickian diffusion to anomalous transport, when the carbon content in coal and penetrant activity increase. Variations of the diffusion coefficients and relaxation constants were determined using a diffusion/relaxation coupled model.