An enzyme-linked immunosorbent assay on a centrifugal platform using magnetic beads

An automated, disk-based, enzyme-linked immunosorbent assay (ELISA) system is presented in this work. Magnetic beads were used as the antibody carriers to improve the assay sensitivity and shorten the reaction time. The magnetic module integrated on the system is capable of controlling the magnetic beads to either move in the incubation stage or immobilize at a specific location during washing stage. This controlling mechanism utilizes a passive controlling approach so that it can be performed through disk spinning without the need of active control from external devices. The movement of the magnetic beads was investigated and the optimal rotational speed was found to be related to the ratio of the processing time to the cycle time of the magnetic beads. Comparing to ELISA conducted on microtiter plates, similar test results could be achieved by the disk-based ELISA but the entire protocol can be finished automatically within 45 min with much less reagent consumption.     

Experimental validation of numerical study on thermoelectric-based heating in an integrated centrifugal microfluidic platform for polymerase chain reaction amplification

A comprehensive study involving numerical analysis and experimental validation of temperature transients within a microchamber was performed for thermocycling operation in an integrated centrifugal microfluidic platform for polymerase chain reaction (PCR) amplification. Controlled heating and cooling of biological samples are essential processes in many sample preparation and detection steps for micro-total analysis systems. Specifically, the PCR process relies on highly controllable and uniform heating of nucleic acid samples for successful and efficient amplification. In these miniaturized systems, the heating process is often performed more rapidly, making the temperature control more difficult, and adding complexity to the integrated hardware system. To gain further insight into the complex temperature profiles within the PCR microchamber, numerical simulations using computational fluid dynamics and computational heat transfer were performed. The designed integrated centrifugal microfluidics platform utilizes thermoelectrics for ice-valving and thermocycling for PCR amplification. Embedded micro-thermocouples were used to record the static and dynamic thermal responses in the experiments. The data collected was subsequently used for computational validation of the numerical predictions for the system response during thermocycling, and these simulations were found to be in agreement with the experimental data to within ∼97%. When thermal contact resistance values were incorporated in the simulations, the numerical predictions were found to be in agreement with the experimental data to within ∼99.9%. This in-depth numerical modeling and experimental validation of a complex single-sided heating platform provide insights into hardware and system design for multi-layered polymer microfluidic systems. In addition, the biological capability along with the practical feasibility of the integrated system is demonstrated by successfully performing PCR amplification of a Group B Streptococcus gene.     

MLTC 上清对同种肿瘤细胞的杀伤作用

为探讨淋巴细胞与肿瘤细胞混合培养中淋巴细胞分泌的细胞毒因子,采用＾３Ｈ－ＴｄＲ掺入试验,测定淋巴细胞和肿瘤细胞混合培养（ＭＬＴＣ）的上清液对艾氏腹水癌细胞（ＥＡＣ）的细胞毒作用以及胸腺素对它的影响。结果表明：混合培养时间不同的ＭＬＴＣ上清对不同瘤龄的ＥＡＣ均具有明显的杀伤作用（Ｐ〈０．０１）;胸腺素能够显著增强ＭＬＴＣ上清对ＥＡＣ的细胞毒效应（Ｐ〈０．０１）。说明在ＭＬＴＣ中,肿瘤细胞能剌激淋巴细     

The centrifugal viscometer

In this study, a viscometer, which can measure the viscosity of low-volume liquids (25 μl) within 30 s, was developed on a centrifugal platform. The centrifugal viscometer consists of a disk platform and a motor. Under disk rotation, centrifugal, Coriolis, and viscosity-induced drag forces result in deflection of liquid flow. The viscosity of the liquid sample is determined by the deflection angle of the liquid, which can be examined through image analysis or visual inspection. The viscosities of a series of Newtonian model fluids were tested by the centrifugal viscometer and the results showed good agreement with the ones tested by a conventional rotational viscometer. Since the centrifugal viscometer only requires a motor to function, the microfluidic disk can be produced in large quantities at a low cost through injection molding, and the deflection angle can be detected through visual inspection, it provides an inexpensive, easy to operate, and portable approach to measure low-volume liquid viscosity.     

基金会需要一个公共平台

<正>作为民间组织的基金会,对于今天的中国社会来说,已经不是什么新鲜事物了。与西方社会那些基金会的百年老店相比,我国大陆的绝大多数基金会是在改革开放以后成立的,虽然它们还年轻,但在总体上已经有了近30年的     

离心泵节能技术探讨

文章根据离心泵现阶段存在的各项问题,从优化节能设计、合理选型、变频调节、合理布置管路、加强维护及保养等方面对离心泵的节能技术措施进行了深入探讨。以期能在离心泵的节能技术工作中有所借鉴,为生产企业、研究学者及用户提供参考。     

基于全球比较的中国汽车产业科技协同创新平台改革建议研究

汽车产业是典型的复杂产业,其发展需要多学科、多领域协同创新平台的支撑。本研究聚焦汽车产业科技协同创新平台,首先从组织架构、科技计划、项目管理三方面剖析了中国原有科技创新体系存在的主要问题;然后对美国、德国、日本等发达国家汽车产业科技创新体系进行了对比研究;最后针对中国汽车产业的发展现状,借鉴发达国家成功经验,从优化组织架构、设计创新链条、建立协同机制等方面提出中国汽车产业科技协同创新平台顶层设计和机制改革建议。     

The role of pre-innovation platform activity for diffusion success: Evidence from consumer innovations on a 3D printing platform

Digital platforms are becoming increasingly important for household sector innovators that seek support for the innovation process and that want to make innovations available to large audiences. Innovation development and diffusion is especially challenging for first-time innovators as they cannot build on experiences from prior innovations. We argue that first-time innovators can increase the diffusion success of their innovations by engaging in pre-innovation platform activities. We use the context of the 3D printing platform Thingiverse to show that a consumer's pre-innovation platform activity increases innovation diffusion success and that frequency, quality and relatedness of a consumer's pre-innovation platform activity promotes this effect. We find support that innovation quality, the use of recombinant innovations, and innovation documentation are three mechanisms through which pre-innovation platform activities translate into higher diffusion success of consumers’ first innovation.     

Building a cross-border e-commerce talent training platform based on logistic regression model

Student success is crucial to the process of building a Cross-border e-commerce (CBEC) talent development platform. Analysis of the important aspects impacting performance and performance prediction are carried out with the goal of enhancing students' academic outcomes. To better forecast student outcomes, a logistic regression model is used for factor analysis, and a penalty function is implemented. Parameters are reconciled using K-fold cross-validation, and then estimated using the coordinate descent technique. Model performance validation findings indicated that the Area Under the curve (AUC) for the minimax concave penalty (MCP) and smoothlyclippedabsolutedeviation(SCAD) penalized logistic regression models were 0.772 and 0.771, respectively. Both the MCP and SCAD penalized logistic regression models have overall accuracies of 0.738 and 0.739, respectively. Researchers found that for MCP, the correlation coefficient was 0.99949, and for SCAD, it was 0.99958, between the projected value and the anticipated value of students' performance. Due to their superior prediction accuracy, the MCP and SCAD penalized logistic regression models may be used as analytical tools in the development of the CBEC talent training platform.     

离心力场对氯酸钠不对称结晶的影响

研究了外在的离心力场对氯酸钠溶液结晶的影响,使用偏光显微镜考察了离心机的不同转速下,氯酸钠结晶过程中手性对称性破缺的统计结果.实验表明,作为一个物理因素,外在的离心力场能明显诱导氯酸钠溶液结晶的手性分布.当离心机转速较大时(如6000r/min),饱和溶液的结晶趋向于仅有一种构型——L型或D型,即能导致氯酸钠结晶的完全手性对称性破缺,且顺时针离心力场中D型晶体数量明显大于L型,而在逆时针离心力场中L型晶体数量却明显大于D型,并均随外力增大而效应增大.这些结果表明,外在离心力场可方向性地对氯酸钠溶液的不对称结晶过程产生重要影响.     

积极打造国际合作大平台

生物物理研究所是我国从事生命科学基础研究的机构。长期以来,我所作为在国际同行中具有重要影响的研究所,在国际交流与合作中一直非常活跃。特别是实施知识创新工程试点工作后,我所与国际著名研究机构和大学开展了更为广泛的合作与交流,并逐步由一般性的学术交流向战略性合作转移,取得了丰硕的成果。近期,我所为实现成为世界上著名的生命科学研究中心之一的新时期发展目标,在新一届领导班子的共同努力下,利用自身的发展优势,创造条件,力图借助多方面的力量,提高我所的国际化水平。为此,我所在原有的工作基础上对国际合作进行了新的构想,采…     

基于SERVQUAL模型科技金融平台服务质量评测——以P2P网贷平台为例

《“十三五”国家科技创新规划》大力支持科技金融服务业发展。以“XK网贷平台”为例,开展200份问卷调查、分析137份有效样本数据,基于SERVQUAL模型、服务期望值和感知值的差距分析,以乘积标度法等工具计算服务质量评价指标及其五个服务维度的权重值,对服务质量进行量化测量及对服务质量差距作分析,最后从五个维度分析该平台服务质量问题,并对P2P网贷及科技金融服务平台的发展提出三个对策建议。     

Black silicon as a platform for bacterial detection

Surface-enhanced Raman scattering (SERS) shows promise for identifying single bacteria, but the short range nature of the effect makes it most sensitive to the cell membrane, which provides limited information for species-level identification. Here, we show that a substrate based on black silicon can be used to impale bacteria on nanoscale SERS-active spikes, thereby producing spectra that convey information about the internal composition of the bacterial capsule. This approach holds great potential for the development of microfluidic devices for the removal and identification of single bacteria in important clinical diagnostics and environmental monitoring applications.Plasma etching of silicon can be used to produce inexpensive, large surface area, nano-textured surfaces known as black silicon. Recently, it has been shown that black silicon nano-needles can impale bacteria¹ and that it can be used as a sensor in microfluidic devices.² When coated by a plasmonic metal, such as gold, the nano-textured surface of black silicon is ideal for use as a surface-enhanced Raman scattering (SERS) sensing platform.³ This work aims to investigate whether gold-coated black silicon nano-needles can be used to both impale bacteria and identify them by SERS. This combination of properties would promote the development of microfluidic devices for the removal and monitoring of bacteria in a wide range of medical, environmental, and industrial applications.⁴Black silicon was fabricated by a reactive ion etching technique,⁵ resulting in pyramidal-shaped spikes of height 185 ± 30 nm, full width at half height of 54 ± 10 nm, and 10 ± 2.4 nm radius of curvature at the tip. Samples were then magnetron sputter coated with 200 nm of gold, as this coating thickness was found to provide a suitable compromise between SERS enhancement and impalement efficiency. E. coli (ATCC 25922) from −80 °C stock was isolated on a nutrient agar plate (Difco nutrient broth, Becton Dickinson) for approximately 12 h. A single E. coli colony was then inoculated from the plate into 20 ml of nutrient broth media and incubated overnight at 37 °C with orbital shaking at 200 rpm. The total biomass of overnight culture was adjusted to an optical density of 0.3 at λ = 600 nm by adding fresh sterile nutrient broth (Cary 50 spectrophotometer, Agilent). The E. coli planktonic cells were washed three times by centrifugation at 12 000 rpm (Centrifuge 5804 R, Eppendorf) for 2 min. The washed cells were then re-suspended in a low strength minimum medium (Dulbecco A, phosphate buffered saline). A volume of 100 μl of solution was pipetted onto substrates and left to incubate for 1 h on the bench. Separate sets of samples were created for scanning electron microscope (SEM) imaging, live/dead staining, and SERS. Three sets were needed as each of these measurements altered the samples and left them unsuitable for further analysis.The first set of samples was washed three times with milliQ water after incubation, allowed to dry and then immediately sputter coated with gold using the Emitech K975x (operating current 35 mA, sputter time 32 s, stage rotation 138 rpm, and vacuum of 1 × 10⁻² mbar). SEM imaging was performed with a Zeiss Supra 40VP in high vacuum mode with a working distance of 5 mm and an accelerating voltage of 3 kV. Figure ​Figure11 shows an example of the different levels of impalement that occurred on the black silicon surface. All cells showed signs of damage, but in some cases, the damage was limited to the perimeter of the cell and the main body appeared whole. In other cases, the entire cell had collapsed onto the spikes.Open in a separate windowFIG. 1.A typical SEM image showing E. coli cells with different levels of impalement on gold-coated black silicon.The second set of samples was used for live/dead staining (Invitrogen BacLight Bacterial Viability Kit L7012) with 3.34 mM SYTO 9 (green fluorescence) and 20 mM propidium iodide (red fluorescence). Equal volumes of both dyes were mixed thoroughly in a tube and added to the sample in a ratio of 3 μl of mixed dye to 1 ml of bacterial suspension. After mixing, a volume of 100 μl of the solution was pipetted onto the substrates, which were then incubated at room temperature in the dark for 15 min, before the staining solution was removed by pipetting. The substrates were then washed three times with milliQ water and mounted on a microscope slide for fluorescence imaging. The substrates were not allowed to dry and were stored in phosphate buffered saline at 4 °C when not in use. An epifluorescence microscope (Olympus IX71) with a mercury lamp source and a 60× water immersion objective was used to collect live/dead images from the substrates. Two filter blocks were used to collect the images: U-MNIBA2 blue excitation narrow band delivered green emission (live) and U-MWIG2 green excitation wide band provided red emission (dead).The live/dead image in Figure ​Figure22 shows a mix of both live and dead cells on the black silicon sample. The prevalence of live cells could be due to the incomplete impalement seen under SEM for some cells. It can also be explained by the sample still being wet during live/dead staining. The cells are dried prior to imaging in the SEM and this could weaken the cell wall and allow capillary forces to draw the cells onto the spikes for impalement. This hypothesis is supported by the large number of cells on the stained sample and the presence of cell groupings and cells imaged during mid-division. If the cells were immediately impaled, then such activity would not have been visible and a greater proportion of red cells would be expected.Open in a separate windowFIG. 2.Epifluorescence image showing live (green) and dead (red) E. coli cells after incubation on gold-coated black silicon.The third set of samples was washed three times with milliQ water after incubation and allowed to dry prior to spectral analysis. SERS spectra were collected with a Renishaw inVia Raman spectrometer operating at 785 nm with a 1200 l/mm grating. Power at the sample was 150 mW focused with a 100 × /0.85 NA objective to obtain a diffraction limited laser spot. The resulting spot size (≤2 μm in diameter) is well matched to the size of the bacterial cells. Spectra were collected with three accumulations of 10 s. Data were background subtracted⁶ and normalised to unity for ease of plotting. A great deal of variability was observed in the resulting spectra, as shown in Figure ​Figure33.Open in a separate windowFIG. 3.SERS spectra of E. coli after incubation on a gold-coated black silicon substrate. The spectrum numbers represent single cells at different locations and different levels of impalement.It should be noted that E. coli SERS is known to produce a high level of variability,^7–12 depending on the experimental setup.¹³ However, the variability seen in the SERS spectra of Fig. ​Fig.33 is unusual for measurements performed under consistent experimental conditions. This increased level of variability may be related to the different levels of impalement seen in Fig. ​Fig.1,1, which results in the probing of different internal components. SERS is a surface sensitive technique, with the signal primarily arising within 2 nm of the metal surface.¹⁴ Note that unlike apertureless nanoprobes¹⁵ or conical plasmonic nanotips,¹⁶ the SERS signal in black silicon arises primarily from “hot spots” between the spikes, where the plasmon resonance field is particularly strong.¹⁷ Therefore, depending on the depth and location of impalement, different biomolecules are expected to be excited by this novel substrate.Some peaks occur in the same position for multiple spectra (e.g., peak positions 420, 893, 1001, 1285, and 1307 cm⁻¹), but there are also a lot of unique peaks. The vertical lines in Fig. ​Fig.33 indicate peaks which have appeared in the literature for SERS of E. coli.^7–12 Spectrum 3 has a high proportion of peaks matching published values. This is also the case for spectrum 5, which shares a few peak positions with spectrum 3. Preliminary peak allocations have identified carbohydrates¹¹ (420 cm⁻¹), tyrosine¹¹ (650 cm⁻¹), adenine^10,11 (706 and 735 cm⁻¹), hypoxanthine⁷ (722 and1373 cm⁻¹), phenylalanine⁹ (1001 cm⁻¹), amide III (Ref. ¹⁰) (1285 cm⁻¹), CH₂ deformation¹² (1556 cm⁻¹), and C=C¹⁰ (1587 cm⁻¹).Given the varying levels of impalement observed in the SEM, it appears that the spike shape and Au coating should be further optimized to ensure that the entire cell is consistently pierced and the internal biomolecules are more comprehensively probed. In this way, it may be possible to obtain a more reproducible SERS spectrum of the internal biomolecular constituents of single bacterial cells, thereby providing rapid identification for medical and environmental diagnostic applications. Given that SERS is insensitive to water,⁴ future work should aim to achieve impalement in an aqueous environment, so that the full capability of microfluidics can be used to separate and concentrate suspended bacteria before presenting them to the substrate for rapid analysis.⁴ This suggests a broad range of potential applications in the detection, monitoring, and control of bacterial contamination.     

基于可信计算平台的电子现金技术

基于可信计算平台提出了一种新的离线电子现金方案,该方案将电子现金、用户身份、平台身份三者有机绑定在一起,利用可信计算平台的认证技术和存储保护功能,极大地增强了电子现金的安全性,同时还具有支付起源非否认、电子现金有限流通期限等特点.该方案对于电子现金的备份,电子现金的盗用和丢失,都提供了良好的保护,并对所提出的电子现金协议进行了详细的安全性分析.     

Pulmonary monoclonal antibody delivery via a portable microfluidic nebulization platform

Nebulizers have considerable advantages over conventional inhalers for pulmonary drug administration, particularly because they do not require coordinated breath actuation to generate and deliver the aerosols. Nevertheless, besides being less amenable to miniaturization and hence portability, some nebulizers are prone to denature macromolecular drugs due to the large forces generated during aerosolization. Here, we demonstrate a novel portable acoustomicrofluidic device capable of nebulizing epidermal growth factor receptor (EGFR) monoclonal antibodies into a fine aerosol mist with a mass median aerodynamic diameter of approximately 1.1 μm, optimal for deep lung deposition via inhalation. The nebulized monoclonal antibodies were tested for their stability, immunoactivity, and pharmacological properties, which confirmed that nebulization did not cause significant degradation of the antibody. In particular, flow cytometry demonstrated that the antigen binding capability of the antibody is retained and able to reduce phosphorylation in cells overexpressing the EGFR, indicating that the aerosols generated by the device were loaded with stable and active monoclonal antibodies. The delivery of antibodies via inhalation, particularly for the treatment of lung cancer, is thus expected to enhance the efficacy of this protein therapeutic by increasing the local concentration where they are needed.     

数字化功能、平台策略与市场绩效的关系研究北大核心CSCDCSSCI

随着数字经济的不断渗透与数字平台的大量涌现,平台模式成为经济发展的重要引擎。虽然现有平台采用了相似的发展策略,但是不同平台的市场绩效存在较大差异,究其原因,平台层特征之一,即平台数字化功能在其中扮演了至关重要的作用。为了深入探究平台数字化功能如何影响平台策略与平台市场绩效之间的关系,本研究基于277份问卷调查数据进行了实证检验。结果发现:(1)平台规模策略、平台排他策略与平台市场绩效之间的关系均受到平台数字化功能的影响;(2)平台规模策略在社群支持功能的影响下,对平台市场绩效的影响更大;(3)平台排他策略在数据赋能功能的影响下,对平台市场绩效的影响更大。本研究从参与者层面和平台层面共同剖析了不同平台市场绩效差异的核心动因,并量化了数字化功能对平台绩效提升的作用效果,贡献于平台绩效管理与数字化功能的相关研究领域。     

基于JQuery Mobile的国际漫游自助服务平台设计与实现

随着移动互联网技术的快速发展,JQuery Mobile框架以其成本低廉、兼容性强、跨平台、使用简单等特性越来越受到移动开发人员的欢迎。文章结合移动用户投诉国际漫游中遇到的实际问题,基于JQuery Mobile技术设计开发了国际漫游自助服务平台。通过使用该平台,有效降低了用户国际漫游相关问题处理时长,提升了用户满意度。