开式向心涡轮背部间隙流动特性的研究

对开式向心涡轮背部间隙流动特性进行计算分析,计算结果和实验符合较好。分析结果表明:背部间隙泄漏流量远小于叶顶间隙泄漏流量,但两者损失大小相当,可见背部间隙与叶顶间隙虽然在形式上相似,但流动特性及损失机理有所不同;背部机匣刮削效应增强了展向二次流强度,在吸力面附近出现较大的高熵区,同时背部间隙泄漏流在展向二次流的带动下源源不断向叶顶方向运动,与主流形成较强的掺混;相比之下,叶顶机匣刮削流和展向二次流相互抵消,叶顶间隙泄漏流被展向二次流限制在叶顶壁角附近,掺混损失相对较小。     

A Renal‐Clearable Macromolecular Reporter for Near‐Infrared Fluorescence Imaging of Bladder Cancer

Bladder cancer (BC) is a prevalent disease with high morbidity and mortality; however, in vivo optical imaging of BC remains challenging because of the lack of cancer‐specific optical agents with high renal clearance. Herein, a macromolecular reporter (CyP1) was synthesized for real‐time near‐infrared fluorescence (NIRF) imaging and urinalysis of BC in living mice. Because of the high renal clearance (ca. 94 % of the injection dosage at 24 h post‐injection) and its cancer biomarker (APN=aminopeptidase N) specificity, CyP1 can be efficiently transported to the bladder and specially turn on its NIRF signal to report the detection of BC in living mice. Moreover, CyP1 can be used for optical urinalysis, permitting the ex vivo tracking of tumor progression for therapeutic evaluation and easy translation of CyP2 as an in vitro diagnostic assay. This study not only provides new opportunities for non‐invasive diagnosis of BC, but also reveals useful guidelines for the development of molecular reporters for the detection of bladder diseases.     

交叉口黄色信号灯和全红时间的改进计算

在道路交叉口正确设置左转车辆的黄色信号灯和全红(所有方向信号灯均为红色，在必要时设置)的时间长度，能够提高交叉口的效率和安全．本文分析了影响2种信号周期设置的各种因素，以及2种信号时间的计算机理，在计算模型中引入了更多的影响因素，使得模型更加合理和符合交叉口的实际情况．同时，对于一些难以量化的人为因素，例如驾驶员的驾驶特性，引入了3个参数，并且根据大量实验数据，给出了这些参数在各种交叉口环境下的参考值．经过这些研究，黄色信号灯和全红时长的计算模型得到了改进，提高了交叉口交通的通行效率和安全．     

High-Performance Liquid Chromatographic Determination of Cefepime and Cefazolin in Human Plasma and Dialysate

A simple high-performance liquid chromatographic (HPLC) method was developed for the simultaneous determination of cefepime and cefazolin in human plasma and dialysate. For component separation, the method utilized a C₁₈ column with an aqueous mobile phase of dibasic potassium hydrogen phosphate (pH 7.0) and methanol gradient at a flow rate of 1 mL min⁻¹. The method demonstrated linearity from 2.0 to 100.0 μg mL⁻¹ (r > 0.999) with detection limit of 1 μg mL⁻¹ for both cefepime and cefazolin. The method was utilized for evaluation of plasma and dialysate samples in a clinical study evaluating the dialyzer clearance of cefepime and cefazolin using high-flux hemodialysis with varying blood flow rates in chronic kidney failure patients undergoing hemodialysis and peritoneal dialysis treatment.     

Characterization of a biopharmaceutical protein and evaluation of its purification process using automated capillary Western blot

This paper describes the application of an automated size‐based capillary Western blot system (Sally instrument) from ProteinSimple, Inc., for biopharmaceutical fusion‐Fc protein characterization and evaluation of its purification process. The fusion‐Fc protein column purification from an excess of single chain Fc polypeptide and removal of an enzyme coexpressed for protein maturation have been demonstrated using an automated capillary Western system. The clearance of a selected host cell protein (HCP) present in cell culture of fusion‐Fc protein was also quantitatively monitored throughout the protein purification process. Additionally, the low levels of fusion‐Fc product‐related impurities detected by traditional slab gel Western blot were confirmed by the automated capillary Western system. Compared to the manual approach, the automated capillary Western blot provides the advantages of ease of operation, higher sample throughput, greater linearity range, and higher precision for protein quantitation.     

含分流叶片的离心压缩机级内三维流场数值分析

使用Fine/Turbo三维粘性计算程序对含分流叶片半开式叶轮的离心压缩机级内三维粘性流场进行数值分析.该程序应用Jameson的中心差分格式结合Yang&Shih k-ε湍流模型,使用时间推进法求解雷诺平均N-S方程,用四阶显式Runge-Kutta法进行时间推进.计算中CFL数取2.5,残差收敛至10-4数量级、计算域进出口质量流量误差小于0.05%时认为收敛.并为进一步的产品优化设计及改进研究打下基础.计算结果表明该模级的数值模拟曲线与实验值吻合良好;叶轮出口截面上两个通道的速度分布极不均匀,右通道的速度比左通道的变化剧烈.为了加快收敛,计算时采用了隐式残差平均法及完全多重网格技术.     

Experimental and numerical investigations of tip injection on tip clearance flow in an axial turbine cascade

This investigation presents detailed experimental measurements of an active tip-clearance control method based on tip injection in a high-turning axial turbine cascade. Besides that, numerical investigations are also conducted to study phenomena which are not easily measured in the experiments. It aims to study the influence of tip injection on tip clearance flow, with emphasis on the effects of injection locations. Detailed flow field measurements were made downstream of the cascade using a three-hole probe. Static pressure distributions were also measured on the blade surface at 50% and 97.5% span, respectively. The results suggest that tip injection can weaken tip clearance flow, reducing the tip clearance mass flow and its associated losses. Meanwhile, the heat transfer condition on the blade tip surface can be also improved significantly. It also can be found that injection chordwise location plays an important role in the redistribution of secondary flow within the cascade passage. When the same number of injection holes and injection mass flow are applied, holes located in the aft part of blade can perform much better than that in the front part.     

衍射透镜在多普勒叶尖间隙检测系统中的应用

提出了用折衍混合单透镜代替多普勒叶尖间距检测系统中的双胶合消色差透镜组.对折衍混合单透镜与双胶合消色差透镜的初级像差进行了分析,设计的折衍混合单透镜与双胶合消色差透镜组相比,像差明显减小,光斑位于艾里斑内;光斑半径的均方根达到0.127.从而大大地降低了系统的尺寸和重量,实现了系统的小型化要求.     

Astrocytic energy metabolism and glutamate formation--relevance for 13C-NMR spectroscopy and importance of cytosolic/mitochondrial trafficking

Glutamate plays a double role in ¹³C-nuclear magnetic resonance (NMR) spectroscopic determination of glucose metabolism in the brain. Bidirectional exchange between initially unlabeled glutamate and labeled α-ketoglutarate, formed from pyruvate via pyruvate dehydrogenase (PDH), indicates the rate of energy metabolism in the tricarboxylic acid (V_TCA) cycle in neurons (V_{PDH, n}) and, with additional computation, also in astrocytes (V_{PDH, g}), as confirmed using the astrocyte-specific substrate [¹³C]acetate. Formation of new molecules of glutamate during increased glutamatergic activity occurs only in astrocytes by combined pyruvate carboxylase (V_PC) and astrocytic PDH activity. V_{PDH, g} accounts for ∼15% of total pyruvate metabolism in the brain cortex, and V_PC accounts for another ∼10%. Since both PDH-generated and PC-generated pyruvates are needed for glutamate synthesis, ∼20/25 (80%) of astrocytic pyruvate metabolism proceed via glutamate formation. Net transmitter glutamate [γ-aminobutyric acid (GABA)] formation requires transfer of newly synthesized α-ketoglutarate to the astrocytic cytosol, α-ketoglutarate transamination to glutamate, amidation to glutamine, glutamine transfer to neurons, its hydrolysis to glutamate and glutamate release (or GABA formation). Glutamate-glutamine cycling, measured as glutamine synthesis rate (V_cycle), also transfers previously released glutamate/GABA to neurons after an initial astrocytic accumulation and measures predominantly glutamate signaling. An empirically established ∼1/1 ratio between glucose metabolism and V_cycle may reflect glucose utilization associated with oxidation/reduction processes during glutamate production, which together with associated transamination processes are balanced by subsequent glutamate oxidation after cessation of increased signaling activity. Astrocytic glutamate formation and subsequent oxidative metabolism provide large amounts of adenosine triphosphate used for accumulation from extracellular clefts of neuronally released K⁺ and glutamate and for cytosolic Ca²⁺ homeostasis.     

多体系统动力学中关节效应模型的研究进展

在一般的多体系统动力学研究中认为运动关节是理想运动副. 然而,实际中的运动关节不仅含有间隙与摩擦,还有间隙引起的关节元素之间的接触碰撞、局部变形和磨损. 多体系统动力学中的关节效应不仅引起了系统的振动和噪声,减小了系统的可靠性和寿命,而且损失了系统的精度和稳定性. 为此,对近十几年多体系统动力学中关节效应的研究进行了详细分析,总结了关节效应中间隙运动学模型、接触力模型与磨损模型在多体系统动力学中的建模过程. 其中,着重分析了多体系统动力学中关节磨损效应的研究进展,并对常用的Reye'shypothesis 和Archard 磨损模型进行了比较,详细地分析了Archard 磨损模型的演变形式以及主要磨损参数(接触应力,接触面积和滑移距离),特别分析了关键磨损参数接触应力的建模方法,解释了基于Winkler 弹性基础理论在求解接触应力时遇到的困难. 另外,介绍了4 种间隙运动副(转动副、移动副、圆柱副和球面副) 的运动学模型. 分析了考虑关节磨损多体系统动力学模型的一般建模方法,并以平面五杆机构为例说明了其建模过程.最后,简要地展望了多体系统动力学中关节效应模型的发展趋势以及应用前景.