Comparative studies on the analysis of glycoproteins and lipopolysaccharides by the gel-based microchip and SDS-PAGE

In order to determine time efficiency between the gel-based microchip (LabChip) and traditional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), glycoproteins and lipopolysaccharides were analyzed in this study. After 90 min of gel electrophoresis, glycoproteins (bovine serum albumin, lysozyme, ovalbumin, and apo-transferrin) and fluorescent lipopolysaccharides (LPS-O and LPS-S) under reducing conditions could be analyzed by SDS-PAGE, and it would take (including imaging and analyzing) more than 3 h. The same sample could also be assayed on a Bioanalyzer in combination with the LabChip, and it would only need 30 min from start to finish. The assay software automatically calculated the size and concentration of each separated peak and displayed the results in real time, thus eliminating time-consuming procedures such as imaging and analyzing. Compared to the traditional reducing SDS-PAGE, LabChip has a faster turnaround time.     

国家科技计划及项目管理中的二八现象和长尾理论的影响浅析

二八定律对科技管理有很大的影响,使科技计划管理和科技项目管理中普遍存在二八现象.长尾理论是网络时代兴起的一种新理论,它强调的是要重视小主体的作用和影响.分析我国科技管理中二八现象和长尾效应,思考长尾效应对我国科技管理的影响,提出二八定律和长尾理论下我国科技计划管理工作的有关建议,将有助于构建基于全生命周期的科技计划管理模式,完善科技计划管理体系.     

Density-dependent separation of encapsulated cells in a microfluidic channel by using a standing surface acoustic wave

This study presents a method for density-based separation of monodisperse encapsulated cells using a standing surface acoustic wave (SSAW) in a microchannel. Even though monodisperse polymer beads can be generated by the state-of-the-art technology in microfluidics, the quantity of encapsulated cells cannot be controlled precisely. In the present study, mono-disperse alginate beads in a laminar flow can be separated based on their density using acoustophoresis. A mixture of beads of equal sizes but dissimilar densities was hydrodynamically focused at the entrance and then actively driven toward the sidewalls by a SSAW. The lateral displacement of a bead is proportional to the density of the bead, i.e., the number of encapsulated cells in an alginate bead. Under optimized conditions, the recovery rate of a target bead group (large-cell-quantity alginate beads) reached up to 97% at a rate of 2300 beads per minute. A cell viability test also confirmed that the encapsulated cells were hardly damaged by the acoustic force. Moreover, cell-encapsulating beads that were cultured for 1 day were separated in a similar manner. In conclusion, this study demonstrated that a SSAW can successfully separate monodisperse particles by their density. With the present technique for separating cell-encapsulating beads, the current cell engineering technology can be significantly advanced.     

Blood viscoelasticity measurement using steady and transient flow controls of blood in a microfluidic analogue of Wheastone-bridge channel

Accurate measurement of blood viscoelasticity including viscosity and elasticity is essential in estimating blood flows in arteries, arterials, and capillaries and in investigating sub-lethal damage of RBCs. Furthermore, the blood viscoelasticity could be clinically used as key indices in monitoring patients with cardiovascular diseases. In this study, we propose a new method to simultaneously measure the viscosity and elasticity of blood by simply controlling the steady and transient blood flows in a microfluidic analogue of Wheastone-bridge channel, without fully integrated sensors and labelling operations. The microfluidic device is designed to have two inlets and outlets, two side channels, and one bridge channel connecting the two side channels. Blood and PBS solution are simultaneously delivered into the microfluidic device as test fluid and reference fluid, respectively. Using a fluidic-circuit model for the microfluidic device, the analytical formula is derived by applying the linear viscoelasticity model for rheological representation of blood. First, in the steady blood flow, the relationship between the viscosity of blood and that of PBS solution (μ_Blood/μ_PBS) is obtained by monitoring the reverse flows in the bridge channel at a specific flow-rate rate (Q_PBS^SS/Q_Blood^L). Next, in the transient blood flow, a sudden increase in the blood flow-rate induces the transient behaviors of the blood flow in the bridge channel. Here, the elasticity (or characteristic time) of blood can be quantitatively measured by analyzing the dynamic movement of blood in the bridge channel. The regression formula (A_Blood (t) = A_α + A_β exp [−(t − t₀)/λ_Blood]) is selected based on the pressure difference (ΔP = P_A − P_B) at each junction (A, B) of both side channels. The characteristic time of blood (λ_Blood) is measured by analyzing the area (A_Blood) filled with blood in the bridge channel by selecting an appropriate detection window in the microscopic images captured by a high-speed camera (frame rate = 200 Hz, total measurement time = 7 s). The elasticity of blood (G_Blood) is identified using the relationship between the characteristic time and the viscosity of blood. For practical demonstrations, the proposed method is successfully applied to evaluate the variations in viscosity and elasticity of various blood samples: (a) various hematocrits form 20% to 50%, (b) thermal-induced treatment (50 °C for 30 min), (c) flow-induced shear stress (53 ± 0.5 mL/h for 120 min), and (d) normal rat versus spontaneously hypertensive rat. Based on these experimental demonstrations, the proposed method can be effectively used to monitor variations in viscosity and elasticity of bloods, even with the absence of fully integrated sensors, tedious labeling and calibrations.     

Discrimination between the human prostate normal cell and cancer cell by using a novel electrical impedance spectroscopy controlling the cross-sectional area of a microfluidic channel

The prostate biopsy method shows a high false negative result because the suspicious tissue considered as cancer is not confirmed during tissue sampling. Thus, repeated biopsy procedures and diagnostic errors in relation to prostate cancer frequently occur. The purpose of this research is to enhance the prostate cancer detection rate by using microfluidic electrical impedance spectroscopy (μEIS), which allows real-time measurement of the electrical impedance of a single human prostate normal cell and cancer cell. The μEIS was equipped with a movable flexible membrane, which is operated by pneumatic pressure to capture the single cell on the surface of sensing electrodes. The forced tight contact between the cell and electrodes makes it possible to measure the electrical characteristics of the cell with a high sensitivity. The μEIS discriminates well between normal human prostate cells (RWPE-1) and cancer cells (PC-3) at 8.7 kHz based on the electrical signal responses of the cells. The average difference rates of admittance magnitude and susceptance are 54.55% and 54.59%, respectively. The developed μEIS also shows high repeatability, which was verified by a deionized water test conducted before and after each cell assay; the maximum variance of both the impedance and admittance at 8.7 kHz was as small as 9.48%.     

流动人口归属感、社会支持对主观幸福感的作用机制研究——以北京市为例

流动人口的产生是我国城镇化发展的必然结果。作为一个游离在城市市民边缘的特殊群体,一直备受社会关注,如何使流动人口更好的融入城市,将成为城市建设与构建和谐社会的重要议题。研究对流动人口的归属感、社会支持和主观幸福感进行了分析。研究结果显示,社会支持对主观幸福感有显著性影响;另外,验证了流动人口的归属感在社会支持和主观幸福感之间的中介作用,结果为提升流动人口主观幸福感提供了理论参考。     

The effects of different syringe volume, needle size and sample volume on blood gas analysis in syringes washed with heparin

Introductıon:

We evaluated the effect of different syringe volume, needle size and sample volume on blood gas analysis in syringes washed with heparin.

Materials and methods:

In this multi-step experimental study, percent dilution ratios (PDRs) and final heparin concentrations (FHCs) were calculated by gravimetric method for determining the effect of syringe volume (1, 2, 5 and 10 mL), needle size (20, 21, 22, 25 and 26 G) and sample volume (0.5, 1, 2, 5 and 10 mL). The effect of different PDRs and FHCs on blood gas and electrolyte parameters were determined. The erroneous results from nonstandardized sampling were evaluated according to RiliBAK’s TEa.

Results:

The increase of PDRs and FHCs was associated with the decrease of syringe volume, the increase of needle size and the decrease of sample volume: from 2.0% and 100 IU/mL in 10 mL-syringe to 7.0% and 351 IU/mL in 1 mL-syringe; from 4.9% and 245 IU/mL in 26G to 7.6% and 380 IU/mL in 20 G with combined 1 mL syringe; from 2.0% and 100 IU/mL in full-filled sample to 34% and 1675 IU/mL in 0.5 mL suctioned sample into 10 mL-syringe. There was no statistical difference in pH; but the percent decreasing in pCO₂, K⁺, iCa²⁺, iMg²⁺; the percent increasing in pO₂ and Na⁺ were statistical significance compared to samples full-filled in syringes. The all changes in pH and pO₂ were acceptable; but the changes in pCO₂, Na⁺, K⁺ and iCa²⁺ were unacceptable according to TEa limits except fullfilled-syringes.

Conclusions:

The changes in PDRs and FHCs due nonstandardized sampling in syringe washed with liquid heparin give rise to erroneous test results for pCO₂ and electrolytes.     

Increased density and coverage uniformity of viruses on a sensor surface by using U-type, T-type, and W-type microfluidic devices

Microorganisms, molecules, or viruses in the fluidic environment are usually at considerably low Reynolds numbers because of small diameters. The viscous forces of molecules and viruses dominate at considerably low Reynolds numbers. This study developed three microfluidic devices, that is, T type, U type, and W type devices, to control the flow movement, which can increase the adhesion density of viruses on the surface of the sensor. The linker 11-mercaptoundecanoic acid (11-MUA) and Turnip yellow mosaic virus (TYMV) were used in this study and measured by a confocal microscope. Fluorescent intensity and coverage of 11-MUA and TYMV were used to identify the adhesion density quantitatively. Results indicate that 11-MUA layers and TYMV disperse randomly by the dipping method. Attachment tests for T-, U-, and W-type devices demonstrated average fluorescence intensities of 1.56, 2.18, and 2.67, respectively, and average fluorescence coverage of 1.31, 1.87, and 2.55 times those of dipping techniques, respectively. The T-type device produced the lowest fluorescence coverage uniformity (10%-80%), whereas the W-type device produced the highest fluorescence coverage uniformity (80%-90%). Fluorescence intensity correlates positively with flow within a specified flow range; however, the exact relationship between fluorescence intensity and flow requires further study. Attachment tests for TYMV virus samples indicated that the W-type device produced an average fluorescence intensity of 3.59 and average fluorescence coverage of 19.13 times greater than those achieved through dipping techniques. Traditional immersion methods achieved fluorescence coverage of 0%-10%, whereas that of the W-type device reached 70%-90%.     

我国OLED产业专利战略研究

OLED是20世纪中期发展起来的一种新型显示技术,在新兴的平板显示领域,OLED将是未来显示行业的明星,有着巨大的市场发展潜力和空间。本文分析了OLED基础专利的许可态势,并在此基础上研究了我国OLED行业专利工作存在的问题以及专利发展的策略。     

The effect of red blood cell aggregation on velocity and cell-depleted layer characteristics of blood in a bifurcating microchannel

Red blood cell (RBC) aggregation is a multifaceted phenomenon, and whether it is generally beneficial or deleterious remains unclear. In order to better understand its effect on microvascular blood flow, the phenomenon must be studied in complex geometries, as it is strongly dependent on time, flow, and geometry. The cell-depleted layer (CDL) which forms at the walls of microvessels has been observed to be enhanced by aggregation; however, details of the characteristics of the CDL in complex regions, such as bifurcations, require further investigation. In the present study, a microchannel with a T-junction was used to analyze the influence of aggregation on the flow field and the CDL. Micro-PIV using RBCs as tracers provided high resolution cell velocity data. CDL characteristics were measured from the same data using a newly developed technique based on motion detection. Skewed and sharpened velocity profiles in the daughter branches were observed, contrary to the behavior of a continuous Newtonian fluid. RBC aggregation was observed to increase the skewness, but decrease the sharpening, of the velocity profiles in the daughter branches. The CDL width was found to be significantly greater, with a wider distribution, in the presence of aggregation and the mean width increased proportionally with the reciprocal of the fraction of flow entering the daughter branch. Aggregation also significantly increased the roughness of the interface between the CDL and the RBC core. The present results provide further insight into how RBC aggregation may affect the flow in complex geometries, which is of importance in both understanding its functions invivo, and utilizing it as a tool in microfluidic devices.     

In-vitro effect of a diabetic serum factor on the generation of superoxide free radical,it’s quenching ability and lysosomal degranulation in normal polymorpho nuclear leucocytes

Normal polymorpho nuclear leucocytes (PMNL) when assaulted with diabetic serum factorin-vitro, recorded enhanced generation of oxygen free radical, and lysosomal degranulation. It also caused a decrease in the cytosolic superoxide dismutase activity. Time-plot studies revealed PMNL susceptibility to diabetic serum factor for oxidative injury and concomitant decrease in SOD, consequential for lysosomal degranulation.