China's first low-temperature superconducting iron remover

In cooperation with engineers from Shandong Huate Magnet Technology Co.,Ltd, scientists and technicians from the CAS Institute of High Energy Physics (IHEP) have developed China's first     

Optofluidic tweezer on a chip

A novel method to realize an optical tweezer involving optofluidic operation in a microchannel is proposed. To manipulate the optical tweezer, light from an optical fiber is passed through both PDMS (polydimethylsiloxane)-air surface lenses and an optofluidic region, which is located in a control channel. Two liquids with different refractive indices (RIs) are introduced into the control channel to form two different flow patterns (i.e., laminar and segmented flows), depending on the liquid compositions, the channel geometry, and the flow rates. By altering the shapes of the interface of the two liquids in the optofluidic region, we can continuously or intermittently control the optical paths of the light. To demonstrate the functionality of the proposed method, optical tweezer operations on a chip are performed. Changing the flow pattern of two liquids with different RIs in the optofluidic region results in successful trapping of a 25 μm diameter microsphere and its displacement by 15 μm.     

CAS inaugurates China's first national energy laboratory

The first state-level lab in China’s energy sector, Dalian National Laboratory for Clean Energy was officially inaugurated at the Dalian Institute of Chemical Physics (DICP) on October 10, 2011. It will focus on the study of the clean conversion and use of fossil fuels, clean and renewable energy technologies as well as strategic planning to address national     

China’s first Australian Garden opens in Guangzhou

The opening for the Australian Garden was jointly held by the BHP Billiton China and the CAS South China Botanical Garden (SCBG) in Guangzhou, capital of south China's Guangdong Province on 18 January. Those present at the ceremony included Prof. Andrew Smith and Prof. Sue Serjeantson from the Australian Academy of Science, Prof. Dave Paterson from the Royal Botanic Garden in Edinburgh, and representatives from the CAS Headquarters, CAS Guangzhou Branch, PHB Billiton China and SCBG.     

China’s first large-scale MA production unit operational in Shanxi

A brainchild of researchers of the CAS Institute of Coal Chemistry, a production unit capable of turning out 20,000 tons of maleic anhydride (MA) per year, the largest of its kind in China, has come into operation recently at the Shanxi Regent Taiming Chemical Co Ltd in Taiyuan, capital of north China's Shanxi Province.     

China’s first successful recovery of ice core in Mongolia

In collaboration with their colleagues from the ROK and Mongolia, CAS scientists achieved their first success in obtaining a 40.18m ice core in a drilling operation from 5 to 20 June in an expedition to the (Hovd) Tsambagarav glacier in Altay Mountains of Mongolia.     

China's first ZnO nanorod field-effect transistor developed at CAS

Recently,an zinc oxide (ZnO) nanorod field-effect transistor (FET), the first of its kind as a nano-device in China, was successfully fabricated by scientists with the CAS Institute     

Crucial control measures to contain China's first Delta variant outbreak

The SARS-CoV-2 B.1.617.2 (Delta) variant flared up in late May in Guangzhou, China. Transmission characteristics of Delta variant were analysed for 153 confirmed cases and two complete transmission chains with seven generations were fully presented. A rapid transmission occurred in five generations within 10 days. The basic reproduction number (R₀) was 3.60 (95% confidence interval: 2.50–5.30). After redefining the concept of close contact, the proportion of confirmed cases discovered from close contacts increased from 43% to 100%. With the usage of a yellow health code, the potential exposed individuals were self-motivated to take a nucleic acid test and regained public access with a negative testing result. Facing the massive requirement of screening, novel facilities like makeshift inflatable laboratories were promptly set up as a vital supplement and 17 cases were found, with 1 pre-symptomatic. The dynamic adjustment of these three interventions resulted in the decline of Rt from 5.00 to 1.00 within 9 days. By breaking the transmission chain and eliminating the transmission source through extending the scope of the close-contact tracing, health-code usage and mass testing, the Guangzhou Delta epidemic was effectively contained.     

Sub-nanomolar detection of thrombin activity on a microfluidic chip

Bioluminescence resonance energy transfer (BRET) is a form of Förster resonance energy transfer. BRET has been shown to support lower limits of detection than fluorescence resonance energy transfer (FRET) but, unlike FRET, has not been widely implemented on microfluidic devices for bioanalytical sensing. We recently reported a microscope-based microfluidic system for BRET-based biosensing, using a hybrid, high quantum-efficiency, form of BRET chemistry. This paper reports the first optical fiber-based system for BRET detection on a microfluidic chip, capable of quantifying photon emissions from the low quantum-efficiency BRET² system. We investigated the effects of varying core diameter and numerical aperture of optical fibers, as well as varying microfluidic channel design and measurement conditions. We optimized the set-up in order to maximize photon counts and minimize the response time. The optimized conditions supported measurement of thrombin activity, with a limit of detection of 20 pM, which is lower than the microscope-based system and more than 20 times lower than concentrations reported to occur in plasma clots.     

High-efficiency rare cell identification on a high-density self-assembled cell arrangement chip

Detection of individual target cells among a large amount of blood cells is a major challenge in clinical diagnosis and laboratory protocols. Many researches show that two dimensional cells array technology can be incorporated into routine laboratory procedures for continuously and quantitatively measuring the dynamic behaviours of large number of living cells in parallel, while allowing other manipulations such as staining, rinsing, and even retrieval of targeted cells. In this study, we present a high-density cell self-assembly technology capable of quickly spreading over 300 000 cells to form a dense mono- to triple-layer cell arrangement in 5 min with minimal stacking of cells by the gentle incorporation of gravity and peripheral micro flow. With this self-assembled cell arrangement (SACA) chip technology, common fluorescent microscopy and immunofluorescence can be utilized for detecting and analyzing target cells after immuno-staining. Validated by experiments with real human peripheral blood samples, the SACA chip is suitable for detecting rare cells in blood samples with a ratio lower than 1/100 000. The identified cells can be isolated and further cultured in-situ on a chip for follow-on research and analysis. Furthermore, this technology does not require external mechanical devices, such as pump and valves, which simplifies operation and reduces system complexity and cost. The SACA chip offers a high-efficient, economical, yet simple scheme for identification and analysis of rare cells. Therefore, potentially SACA chip may provide a feasible and economical platform for rare cell detection in the clinic.     

A microfluidic co-culture system to monitor tumor-stromal interactions on a chip

The living cells are arranged in a complex natural environment wherein they interact with extracellular matrix and other neighboring cells. Cell-cell interactions, especially those between distinct phenotypes, have attracted particular interest due to the significant physiological relevance they can reveal for both fundamental and applied biomedical research. To study cell-cell interactions, it is necessary to develop co-culture systems, where different cell types can be cultured within the same confined space. Although the current advancement in lab-on-a-chip technology has allowed the creation of in vitro models to mimic the complexity of in vivo environment, it is still rather challenging to create such co-culture systems for easy control of different colonies of cells. In this paper, we have demonstrated a straightforward method for the development of an on-chip co-culture system. It involves a series of steps to selectively change the surface property for discriminative cell seeding and to induce cellular interaction in a co-culture region. Bone marrow stromal cells (HS5) and a liver tumor cell line (HuH7) have been used to demonstrate this co-culture model. The cell migration and cellular interaction have been analyzed using microscopy and biochemical assays. This co-culture system could be used as a disease model to obtain biological insight of pathological progression, as well as a tool to evaluate the efficacy of different drugs for pharmaceutical studies.     

Construction and operation of a microrobot based on magnetotactic bacteria in a microfluidic chip

Magnetotactic bacteria (MTB) are capable of swimming along magnetic field lines. This unique feature renders them suitable in the development of magnetic-guided, auto-propelled microrobots to serve in target molecule separation and detection, drug delivery, or target cell screening in a microfluidic chip. The biotechnology to couple these bacteria with functional loads to form microrobots is the critical point in its application. Although an immunoreaction approach to attach functional loads to intact MTB was suggested, details on its realization were hardly mentioned. In the current paper, MTB-microrobots were constructed by attaching 2 μm diameter microbeads to marine magnetotactic ovoid MO-1 cells through immunoreactions. These microrobots were controlled using a special control and tracking system. Experimental results prove that the attachment efficiency can be improved to ∼30% via an immunoreaction. The motility of the bacteria attached with different number of loads was also assessed. The results show that MTB can transport one load at a velocity of ∼21 μm/s and still move and survive for over 30 min. The control and tracking system is fully capable of directing and monitoring the movement of the MTB-microrobots. The rotating magnetic fields can stop the microrobots by trapping them as they swim within a circular field with a controllable size. The system has potential use in chemical analyses and medical diagnoses using biochips as well as in nano/microscale transport.     

Rare cell isolation and profiling on a hybrid magnetic/size-sorting chip

We present a hybrid magnetic/size-sorting (HMSS) chip for isolation and molecular analyses of circulating tumor cells (CTCs). The chip employs both negative and positive cell selection in order to provide high throughput, unbiased CTC enrichment. Specifically, the system utilizes a self-assembled magnet to generate high magnetic forces and a weir-style structure for cell sorting. The resulting device thus can perform multiple functions, including magnetic depletion, size-selective cell capture, and on-chip molecular staining. With such capacities, the HMSS device allowed one-step CTC isolation and single cell detection from whole blood, tested with spiked cancer cells. The system further facilitated the study of individual CTCs for heterogeneity in molecular marker expression.Circulating tumor cells (CTCs) have emerged as an important biomarker in clinical practice as well as in fundamental research.^{1, 2} CTCs, shed from primary tumors, have been shown to be an early harbinger of tumor expansion and metastasis³ and have been used to predict disease progression, response to treatment, relapse, and overall survival.^{4, 5, 6} Recent work has shown that CTCs display distinct proteomic and genetic profiles; for example, CTCs in pancreatic cancer, have increased RNA expression of Wnt, implicating this pathway in metastasis.⁷ Proteomic characterization of proliferative markers such as Ki-67, and hormonal markers such as androgen receptor in prostate cancer, also have been shown to be predictive of treatment outcome.^{8, 9}Despite such clinical potential of CTCs, their routine detection and characterization still remains a significant technical challenge.¹⁰ The task requires screening of a large number of cells (e.g., > 10⁷ cells in 10 ml blood) and enrichment of heterogeneous targets against a complex biological background. Two main methods of CTC isolation are typically used: positive and negative selection. In positive selection, CTCs are directly isolated from blood via size-based filtration^{11, 12, 13, 14, 15, 16, 17, 18, 19, 20} or antibody-based capture.^{1, 8, 21} Negative depletion reduces abundant blood cells, often by immunomagnetic separation, for downstream CTC enrichment.²² Both approaches have been used for high throughput CTC isolation from whole blood (SI Table 1).²³ Each method, however, has its own inherent limitations. Positive enrichment could be biased by its selection criteria (e.g., cell size and cell surface markers). Negative selection, albeit unbiased, often requires complex sample processing (e.g., multiple washing steps for CTC isolation) that could result in cell loss.We hypothesized that both positive and negative selection could be combined in a single platform to enable (1) highly efficient and unbiased CTC purification, and (2) in-situ molecular analyses of collected cells. As a proof-of-concept, we herein describe a hybrid magnetic/size-sorting (HMSS) system that integrates magnetic and size-based isolation into a compact microfluidic chip. The HMSS first uses a magnetic filter to deplete leukocytes through immunomagnetic capture. Samples then pass through a size-sorter region that traps individual cells at predefined locations. Since abundant leukocytes are removed by the magnetic filter, the size-sorter could have a low size cut-off (∼5 μm), which allows for the unbiased capture of even small cancer cells. Furthermore, molecular probes can be introduced to perform on-chip, multiplexed analyses at single-cell resolution. We evaluated the utility of the developed system by capturing and profiling tumor cells in whole blood. The HMSS offers the advantages of both negative and positive selection and thereby differs from the recently reported iChip system²⁴ which can operate only in either a negative or a positive selection mode.     

On-chip antibody immobilization for on-demand and rapid immunoassay on a microfluidic chip

Immunoassay is one of the important applications of microfluidic chips and many methodologies were reported for decreasing sample∕reagent volume, shortening assay time, and so on. Micro-enzyme-linked immunosorbent assay (micro-ELISA) is our method that utilizes packed microbeads in the microfluidic channel and the immunoreactions are induced on the beads surface. Due to the large surface-to-volume ratio and small analytical volume, excellent performances have been verified in assay time and sample∕reagent volume. In order to realize the micro-ELISA, one of the important processes is the immobilization of antibody on the beads surface. Previously, the immobilization process was performed in a macroscale tube by physisorption of antibody, and long time (2 h) and large amount of antibody (or high concentration) were required for the immobilization. In addition, the processes including the reaction and washing were laborious, and changing the analyte was not easy. In this research, we integrated the immobilization process into a microfluidic chip by applying the avidin-biotin surface chemistry. The integration enabled very fast (1 min) immobilization with very small amount of precious antibody consumption (100 ng) for one assay. Because the laborious immobilization process can be automatically performed on the microfluidic chip, ELISA method became very easy. On-demand immunoassay was also possible just by changing the antibodies without using large amount of precious antibodies. Finally, the analytical performance was investigated by measuring C-reactive protein and good performance (limit of detection <20 ng∕ml) was verified.     

Development and evaluation of realistic microbioassays in freely suspended droplets on a chip

A novel technique for biomolecular detection in microliter droplets floating on the surface of high density oil is presented. Each droplet was captured and manipulated dielectrophoretically and was used as a site for a microscopic bioassay based on agglutination of antibody-conjugated particles. The results were read out by the pattern of unagglomerated gold nanoparticles collected on the droplet surface. Two formats of bioassays, namely gold only agglutination and gold and latex agglutination, were investigated experimentally by varying analyte concentration, particle size and concentration, number of antigen binding sites per particle, time for incubation, and rate of particle collection on the droplet surface. The microbioassays performance was also evaluated with ricin antibodies and compared to the ricin assays in field use. It is estimated that the droplet based assays require 100× smaller sample volume and are ten times more sensitive, though they require longer times to complete. The experiments were interpreted by modeling the kinetics of particle agglutination and mass transfer processes inside the droplets. The incubation time and antigen concentration values calculated by the model correlate well with the experimental results. The results could allow for development of efficient immunoassays on a chip requiring even smaller sample volumes.     

基于单片机的输液系统的设计

针对医院在对病人静脉输液治疗监护这个任务繁重的问题,设计了一种采用单片机AT89C51为核心,以键盘、碰触开关及红外光电开关为输入系统,以液晶、声光报警电路及步进电机为输出系统的智能化输液控制及监控系统.     

FTPA:一种具有可配置核的灵活多核处理器结构

提出一个灵活多核处理器结构:FTPA.首先,通过将单个超块独立映射到单个物理核,FTPA有效减少了超块执行时指令间通信开销.其次,通过将物理核资源划分为需要频繁调整的计算资源和不经常重构的共享资源分别管理,FTPA有效降低了逻辑核的重构开销.最后,通过将计算资源在逻辑上组织成环形拓扑,FTPA实现了逻辑核的任意粒度调整,提供高度的灵活性.运行SPEC2K测试程序的结果显示,FTPA比已有的灵活多核结构TFlex性能平均提升19.2％.     

Integrated electrical concentration and lysis of cells in a microfluidic chip

Lysing cells is an important step in the analysis of intracellular contents. Concentrating cells is often required in order to acquire adequate cells for lysis. This work presents an integrated concentration and lysis of mammalian cells in a constriction microchannel using dc-biased ac electric fields. By adjusting the dc component, the electrokinetic cell motion can be precisely controlled, leading to an easy switch between concentration and lysis of red blood cells in the channel constriction. These two operations are also used in conjunction to demonstrate a continuous concentration and separation of leukemia cells from red blood cells in the same microchannel. The observed cell behaviors agree reasonably with the simulation results.     

基于VW2010的视频会议系统终端机设计

文章提出了一种基于VW2010的视频会议系统终端机设计方案;论述了该系统压缩解压缩模块的工作原理,提供了软硬件设计。     

以单片机为核心的智能棉花水分检测仪的研究

为实现棉花水分的智能化检测要求,设计了一种以STC89C52RC单片机为核心的棉花水分检测仪,介绍了仪器的组成及工作原理,进行了系统的硬件和软件设计及调试。通过选择合适电路元件,改进设计方法,该检测仪满足棉花水分智能化检测的可靠性、快速性、稳定性要求。