基于LabVIEW平台的双脉冲电流法在气-液两相环状流壁面剪切力测量中的应用

建立了液膜厚度与壁面剪切力的模型,通过双脉冲电流法测量出气-液两相流环状流的壁面液膜厚度,进而计算出壁面剪切力值。优化设计了电导式纵向四电极传感器,采用环形电极进行电流激励与电压信号获取。整套系统的数据采集、公式换算都以LabVIEW为平台并结合Matlab完成。     

Morphology Evolution of the Microcellular Polymethyl Methacrylate with Supercritical CO2: Effects of Shear Stress and Orthogonal Vibration

This study presents a foaming system that was developed to generate shear stress as well as oscillatory mechanical vibration in an orthogonal direction. The microcellular processes of PMMA specimens blown with ScCO₂ have been conducted to find the optimal processing parameters under the static conditions as well as dynamic conditions. It is evident that the cells are drawn into elliptical geometries sheared circumferential by the rotor rotation in isolation. However, the orthogonal pulsatile axial vibration superimposed on the polymer melt synchronously drives the oriented and elongated cells to isotropy as well as a more homogenous cells distribution and planar structure.     

Investigation of Wall Shear Stress in Cardiovascular Research and in Clinical Practice—From Bench to Bedside

In the 1900s, researchers established animal models experimentally to induce atherosclerosis by feeding them with a cholesterol-rich diet. It is now accepted that high circulating cholesterol is one of the main causes of atherosclerosis; however, plaque localization cannot be explained solely by hyperlipidemia. A tremendous amount of studies has demonstrated that hemodynamic forces modify endothelial athero-susceptibility phenotypes. Endothelial cells possess mechanosensors on the apical surface to detect a blood stream-induced force on the vessel wall, known as “wall shear stress (WSS)”, and induce cellular and molecular responses. Investigations to elucidate the mechanisms of this process are on-going: on the one hand, hemodynamics in complex vessel systems have been described in detail, owing to the recent progress in imaging and computational techniques. On the other hand, investigations using unique in vitro chamber systems with various flow applications have enhanced the understanding of WSS-induced changes in endothelial cell function and the involvement of the glycocalyx, the apical surface layer of endothelial cells, in this process. In the clinical setting, attempts have been made to measure WSS and/or glycocalyx degradation non-invasively, for the purpose of their diagnostic utilization. An increasing body of evidence shows that WSS, as well as serum glycocalyx components, can serve as a predicting factor for atherosclerosis development and, most importantly, for the rupture of plaques in patients with high risk of coronary heart disease.     

应用微地震法进行地应力及压裂缝方向监测研究

XC油区的主力油层属于低渗-超低渗储层,通过压裂作业来提高储层的渗透能力,是生产中的一个至关重要的环节.压裂效果的好坏能够直接影响到油田的后续产量.而对压裂裂缝进行监测,获取压裂裂缝的基本参数,是评价压裂效果的基础之一.本文采用最常用的人工裂缝监测技术-微地震法,对XC油区5口压裂井压裂缝进行了监测和分析研究,确定了地应力的方向,对该地区的后续压裂方案制定及井网部署具有一定的参考意义.     

Tribological Design by Molecular Dynamics Simulation: Influence of the Molecular Structure on Wall Slip and Bulk Shear

The tribological properties of a complex branched-hydrocarbon oil under shear in a gap between smooth iron atom surfaces were studied by large-scale molecular dynamics (MD) simulation. The liquid was a nonpolar lubricant, i.e. a polyalphaolefin (PAO) oil mixture of 1-decane dimer, trimer, and tetramer molecules. The rheological characteristics of the lubricant, including the shear stress and viscosity as well as the relaxation time of the liquid molecule, were calculated. The results show that, as the number of branches of the liquid molecule increases, the shear stresses and the wall slip increase. However, for a mixture fluid containing three different branched molecules, the wall slip decreases in comparison to a liquid consisting of only one kind of branched molecule.     

用户满意度指数测评方法及其在石化行业应用前景探讨

简单介绍了用户满意度指数测评方法及国内外应用情况，并对其在石化行业的应用提出了一些建议。     

A comparison of local phosphorescence detection and fluid dynamic gauging methods for studying the removal of cohesive fouling layers: Effect of layer roughness

The performance of industrial cleaning in place (CIP) procedures is critically important for food manufacture. CIP has yet to be optimised for many processes, in part since the mechanisms involved in cleaning are not fully understood. Laboratory tests have an important role in guiding industrial trials, and this paper introduces and compares two experimental techniques developed for studying CIP mechanisms: local phosphorescence detection (LPD), and scanning fluid dynamic gauging (sFDG).To illustrate the comparison, each technique is used to investigate the influence of soil topology on the cleaning of pre-gelatinised starch-based layers from stainless steel (SS 316) substrates by aqueous NaOH solutions at ambient temperature. The roughness of the soil surface is varied by incorporating zinc sulphide particles with different particle size distributions (range 1–80 μm) into the starch suspensions. The soil roughness increased with the use of larger particles, increasing the 3D arithmetic mean roughness (S_a) of the dry layers (range 0.37–3.33 μm). Rough layers were cleaned more readily than those containing small inclusions, with a good correlation between the cleaning rates observed during LPD and FDG measurements. The LPD technique, which is an instrumented CIP test, gives a better indication of the cleaning time, while sFDG measurements provide further insight into the removal mechanisms.     

Molecular dynamics modeling of the structure, dynamics and energetics of mineral-water interfaces: Application to cement materials

This paper reviews molecular modeling studies of water structure in nano-confinement and at fluid-solid interfaces and presents new molecular dynamics (MD) modeling results for water on the surface of tobermorite. MD modeling provides detailed information about the structure, dynamics and energetics of water at solid surfaces and in confinement that can add significant additional molecular scale insight to experimental results. For the tobermorite (001) surface the results show strong structuring of water in the channels between the drietkette silicate chains and above the surface due to the development of an integrated H-bond network involving the water and the surface sites. Calculated diffusion coefficients for the surface-associated water are in good agreement with published experimental results.     

Acceleration and quantitative evaluation of degradation for corrosion protective coatings on buried pipeline: Part II. Application to the evaluation of polyethylene and coal-tar enamel coatings

The pulsed potentiostatic polarization technique proposed previously has been applied to evaluate the electrochemical degradation of polyethylene and coal-tar enamel coated SS400 for buried pipeline. The degradation of coated systems was accelerated and evaluated using electrochemical techniques (pulsed potentiostatic polarization test, electrochemical impedance spectroscopy) and surface analyses (scanning electron microscopy and energy dispersive X-ray spectroscopy). It was found that polyethylene coating had better protective performance than coal-tar enamel coating due to its low porosity. It was confirmed that the electrochemically accelerated test is an effective technique in the evaluation of coating performance.     

Structural and Computational Studies of the SARS-CoV-2 Spike Protein Binding Mechanisms with Nanobodies: From Structure and Dynamics to Avidity-Driven Nanobody Engineering

Nanobodies provide important advantages over traditional antibodies, including their smaller size and robust biochemical properties such as high thermal stability, high solubility, and the ability to be bioengineered into novel multivalent, multi-specific, and high-affinity molecules, making them a class of emerging powerful therapies against SARS-CoV-2. Recent research efforts on the design, protein engineering, and structure-functional characterization of nanobodies and their binding with SARS-CoV-2 S proteins reflected a growing realization that nanobody combinations can exploit distinct binding epitopes and leverage the intrinsic plasticity of the conformational landscape for the SARS-CoV-2 S protein to produce efficient neutralizing and mutation resistant characteristics. Structural and computational studies have also been instrumental in quantifying the structure, dynamics, and energetics of the SARS-CoV-2 spike protein binding with nanobodies. In this review, a comprehensive analysis of the current structural, biophysical, and computational biology investigations of SARS-CoV-2 S proteins and their complexes with distinct classes of nanobodies targeting different binding sites is presented. The analysis of computational studies is supplemented by an in-depth examination of mutational scanning simulations and identification of binding energy hotspots for distinct nanobody classes. The review is focused on the analysis of mechanisms underlying synergistic binding of multivalent nanobodies that can be superior to single nanobodies and conventional nanobody cocktails in combating escape mutations by effectively leveraging binding avidity and allosteric cooperativity. We discuss how structural insights and protein engineering approaches together with computational biology tools can aid in the rational design of synergistic combinations that exhibit superior binding and neutralization characteristics owing to avidity-mediated mechanisms.     

Preparation of Mesoporous Ni–alumina Catalyst by One-step Sol–gel Method: Control of Textural Properties and Catalytic Application to the Hydrodechlorination of o-dichlorobenzene

Mesoporous Ni–alumina catalysts (Ni–alumina-pre and Ni–alumina-post) were synthesized by one-step sol–gel method using micelle complex comprising lauric acid and nickel ion as a template with metal source and using aluminum sec-butoxide as an aluminum source. The Ni–alumina catalysts showed relatively high surface areas (303 m²/g for Ni–alumina-pre and 331 m²/g for Ni–alumina-post) and narrow pore size distributions centered at ca. 4 nm. Highly dispersed Ni particles were observed in the Ni–alumina catalysts (ca. 5.2 nm for Ni–alumina-pre and ca. 6.8 nm for Ni–alumina-post) after reduction at 550 °C, while a catalyst prepared without a template (NiAl-comp) exhibited inferior porosity with large metal particles (ca. 12.3 nm). Mesoporous Ni–alumina catalysts with different porosity were obtained by employing different hydrolysis step of aluminum source. When aluminum source was hydrolyzed under the presence of micelle complex, a supported Ni catalyst with highly developed framework mesoporosity was obtained (Ni–alumina-post). On the other hand, when aluminum source was pre-hydrolyzed followed by mixing with micelle solution, the resulting catalyst (Ni–alumina-pre) retained high portion of textural porosity. It was revealed that the hydrolysis method employed in this research affected not only textural properties but also metal-support interaction in the Ni–alumina catalysts. It was also found that the Ni–alumina-pre catalyst exhibited weaker interaction between nickel and alumina than the Ni–alumina-post, leading to higher degree of reduction in the Ni–alumina-pre catalyst. In the hydrodechlorination of o-dichlorobenzene, the Ni–alumina catalysts exhibited better catalytic performance than the NiAl-comp catalyst, which was attributed to higher metal dispersion in the Ni–alumina catalysts. In particular, the Ni–alumina-pre catalyst showing 1.5 times higher degree of reduction and larger amounts of o-dichlorobenzene adsorption exhibited better catalytic performance than the Ni–alumina-post catalyst.     

Comparing the Osteogenic Potential and Bone Regeneration Capacities of Dedifferentiated Fat Cells and Adipose-Derived Stem Cells In Vitro and In Vivo: Application of DFAT Cells Isolated by a Mesh Method

Background: We investigated and compared the osteogenic potential and bone regeneration capacities of dedifferentiated fat cells (DFAT cells) and adipose-derived stem cells (ASCs). Method: We isolated DFAT cells and ASCs from GFP mice. DFAT cells were established by a new culture method using a mesh culture instead of a ceiling culture. The isolated DFAT cells and ASCs were incubated in osteogenic medium, then alizarin red staining, alkaline phosphatase (ALP) assays, and RT-PCR (for RUNX2, osteopontin, DLX5, osterix, and osteocalcin) were performed to evaluate the osteoblastic differentiation ability of both cell types in vitro. In vivo, the DFAT cells and ASCs were incubated in osteogenic medium for four weeks and seeded on collagen composite scaffolds, then implanted subcutaneously into the backs of mice. We then performed hematoxylin and eosin staining and immunostaining for GFP and osteocalcin. Results: The alizarin red-stained areas in DFAT cells showed weak calcification ability at two weeks, but high calcification ability at three weeks, similar to ASCs. The ALP levels of ASCs increased earlier than in DFAT cells and showed a significant difference (p < 0.05) at 6 and 9 days. The ALP levels of DFATs were higher than those of ASCs after 12 days. The expression levels of osteoblast marker genes (osterix and osteocalcin) of DFAT cells and ASCs were higher after osteogenic differentiation culture. Conclusion: DFAT cells are easily isolated from a small amount of adipose tissue and are readily expanded with high purity; thus, DFAT cells are applicable to many tissue-engineering strategies and cell-based therapies.     

A Desymmetrization Approach to the Enantiopure syn/anti‐1,5‐Diols via Hydrolytic Kinetic Resolution (HKR) of Functionalized meso‐Bis‐Epoxides: Further Elaboration to syn/syn‐1,3,5‐Triols and Application to the Formal Synthesis of Cryptocarya Diacetate

A new approach has been developed for the synthesis of enantiopure syn/anti‐1,5‐diols by desymmetrization of functionalized meso‐bis‐epoxides using hydrolytic kinetic resolution (HKR). The usage of this protocol was demonstrated by converting syn‐1,5‐diols into syn/syn‐1,3,5‐triols and its subseqent application to the formal synthesis of cryptocarya diacetate.