Single cell manipulation, analytics, and label-free protein detection in microfluidic devices for systems nanobiology

Single cell analytics for proteomic analysis is considered a key method in the framework of systems nanobiology which allows a novel proteomics without being subjected to ensemble-averaging, cell-cycle, or cell-population effects. We are currently developing a single cell analytical method for protein fingerprinting combining a structured microfluidic device with latest optical laser technology for single cell manipulation (trapping and steering), free-solution electrophoretical protein separation, and (label-free) protein detection. In this paper we report on first results of this novel analytical device focusing on three main issues. First, single biological cells were trapped, injected, steered, and deposited by means of optical tweezers in a poly(dimethylsiloxane) microfluidic device and consecutively lysed with SDS at a predefined position. Second, separation and detection of fluorescent dyes, amino acids, and proteins were achieved with LIF detection in the visible (VIS) (488 nm) as well as in the deep UV (266 nm) spectral range for label-free, native protein detection. Minute concentrations of 100 fM injected fluorescein could be detected in the VIS and a first protein separation and label-free detection could be achieved in the UV spectral range. Third, first analytical experiments with single Sf9 insect cells (Spodoptera frugiperda) in a tailored microfluidic device exhibiting distinct electropherograms of a green fluorescent protein-construct proved the validity of the concept. Thus, the presented microfluidic concept allows novel and fascinating single cell experiments for systems nanobiology in the future.     

Microfabricated bioreactor chips for immobilised enzyme assays

A microfabricated device is reported that has been designed to permit the in situ packing of a section of channel with enzyme immobilised onto controlled pore glass (CPG). It is fabricated from glass and polydimethylsiloxane and to prevent dead volumes, has dedicated channels for packing the reactor. The device has the advantage of being simple in design, the flow through enzyme reactor channel being simply a widened section of the analyte channel. The system is suitable for both hydrodynamic and electro-osmotic pumping, and is designed such that when the packing is exhausted it can be repacked. Controlled pore glass provides a reproducible none swelling, high porosity medium onto which the enzyme could be immobilised. The large particle size meant that it was vital to optimise the immobilisation procedure in order to achieve acceptable enzyme activity. The microfabricated device was developed with two enzymes of different molecular masses; alkaline phosphatase and xanthine oxidase. The pore size of the CPG was found to be very important for xanthine oxidase, where the 697 Å pore size (120-200 mesh) CPG was found to give the highest activity (18-20% activity retained after immobilisation). The microfabricated device was used for the assay of p-nitrophenyl phosphate and hypoxanthine with spectrophotometric detection at 405 and 470 nm, respectively. The limits of detection were 5 and 8 μM, respectively.     

纳米晶La_（1－_x）Sr_xFeO_3的合成及气敏特性的研究

用柠檬酸盐法合成出Ｌａ_（１－_ｘ）Ｓｒ_ｘＦｅＯ_３（ｘ＝０．１，０．２，０．３，０．４）原粉，再经固相反应得到纳米晶粉末，用ＴＧ、ＤＴＡ、ＸＲＤ、ＩＲ进行了表征，确证复合氧化物Ｌａ_（１－_ｘ）Ｓｒ_ｘＦｅＯ_３为钙钛矿型结构，粒径在１０～２５ｎｍ之间。实验结果表明，随着固相反应条件不同，产物粒径呈规律性变化．气敏特性研究表明，该纳米晶材料对乙醇有较高的选择性和灵敏度，其选择性顺序为Ｌａ_（０．９）Ｓｒ_（０．１）ＦｅＯ_３＞ＬａＦｅＯ_３＞ＬａＦｅＯ_３（大晶粒）。     

本征导电聚合物的智能性

在化学掺杂或电化学掺杂过程中，性质发生可逆性变化的本征导电聚合物是一种潜在的智能材料，可望实现或部分实现传感、处理和执竽功能，适于制成电机执行器、智能窗、化学分离与释放体系、传感器和非线性光学器件等。     

Immanant positivity for Catalan-Stieltjes matrices

We give some sufficient conditions for the nonnegativity of immanants of square submatrices of Catalan-Stieltjes matrices and their corresponding Hankel matrices. To obtain these sufficient conditions, we construct new planar networks with a recursive nature for Catalan-Stieltjes matrices. As applications, we provide a unified way to produce inequalities for many combinatorial polynomials, such as the Eulerian polynomials, Schröder polynomials, and Narayana polynomials.     

差分无源器件的设计

在现代无线通信系统中,差分电路相比单端电路而言具有更强的抗干扰能力,因此受到了国内外学者的广泛关注。文章介绍了混合模散射参数、差分器件设计中常用的微带线和缝隙线及两种传输线之间的相互转化,并介绍了基于微带线和缝隙线转换结构的两种全差分带通滤波器。两种滤波器分别实现了多频段和宽带的差模传输特性以及宽带的共模抑制特性。文章还给出了差分耦合器、差分功分器和差分天线等差分器件的设计。仿真与实测结果吻合较好,验证了设计方法的正确性。     

Interfacial Proton Supply/Filtration Regulates the Dynamics of Electrocatalytic Nitrogen Reduction Reaction: A Perspective

As a promising energy carrier, ammonia synthesis by electrocatalytic nitrogen reduction reaction (eNRR) is a promising green and low-carbon ammonia synthesis strategy that can replace the traditional Haber–Bosch process. However, the development of eNRR processes is mainly severely constrained by competitive hydrogen evolution reaction (HER), and the corresponding strategies to inhibit this adverse side reaction to obtain high eNRR selectivity are still limited. In addition, for this complex reaction involving gas–liquid–solid three-phase interface and proton/electron transfer, it is great significance to analyze and summarize the existing inhibition HER strategies from the viewpoint of dynamics. In view of this, this work reviews proton supply/filtration regulation strategy in catalytic system, allowing a systematic survey of the literature focusing on interface membrane regulation (inorganic membrane and organic membrane), electrolyte regulation (metal-mediated strategy and electrolyte ion regulation strategy) and system device design (electrode structure design and electrolytic cell device design). Constructive catalytic system design guidance is also suggested to inhibit hydrogen evolution and improve NH₃ selectivity, aiming for scalable and economically feasible applications.     

Secure communication in CloudIoT through design of a lightweight authentication and session key agreement scheme

Internet of Things (IoT) is a newly emerged paradigm where multiple embedded devices, known as things, are connected via the Internet to collect, share, and analyze data from the environment. In order to overcome the limited storage and processing capacity constraint of IoT devices, it is now possible to integrate them with cloud servers as large resource pools. Such integration, though bringing applicability of IoT in many domains, raises concerns regarding the authentication of these devices while establishing secure communications to cloud servers. Recently, Kumari et al proposed an authentication scheme based on elliptic curve cryptography (ECC) for IoT and cloud servers and claimed that it satisfies all security requirements and is secure against various attacks. In this paper, we first prove that the scheme of Kumari et al is susceptible to various attacks, including the replay attack and stolen-verifier attack. We then propose a lightweight authentication protocol for secure communication of IoT embedded devices and cloud servers. The proposed scheme is proved to provide essential security requirements such as mutual authentication, device anonymity, and perfect forward secrecy and is robust against security attacks. We also formally verify the security of the proposed protocol using BAN logic and also the Scyther tool. We also evaluate the computation and communication costs of the proposed scheme and demonstrate that the proposed scheme incurs minimum computation and communication overhead, compared to related schemes, making it suitable for IoT environments with low processing and storage capacity.     

Tetrabutylammonium Bromide Functionalized Ti3C2Tx MXene as Versatile Cathode Buffer Layer for Efficient and Stable Inverted Perovskite Solar Cells

2D Ti₃C₂T_x MXene, possessing facile preparation, high electrical conductivity, flexibility, and solution processability, shows good application potential for enhancing device performance of perovskite solar cells (PVSCs). In this study, tetrabutylammonium bromide functionalized Ti₃C₂T_x (TBAB-Ti₃C₂T_x) is developed as cathode buffer layer (CBL) to regulate the PCBM/Ag cathode interfacial property for the first time. By virtue of the charge transfer from TBAB to Ti₃C₂T_x demonstrated by electron paramagnetic resonance and density functional theory, the TBAB-Ti₃C₂T_x CBL with high electrical conductivity exhibits significantly reduced work function of 3.9 eV, which enables optimization of energy level alignment and enhancement of charge extraction. Moreover, the TBAB-Ti₃C₂T_x CBL can effectively inhibit the migration of iodine ions from perovskite layer to Ag cathode, which synergistically suppresses defect states and reduce charge recombination. Consequently, utilizing MAPbI₃ perovskite without post-treatment, the TBAB-Ti₃C₂T_x based device exhibits a dramatically improved power conversion efficiency of 21.65% with significantly improved operational stability, which is one of the best efficiencies reported for the devices based on MAPbI₃/PCBM with different CBLs. These results indicate that TBAB-Ti₃C₂T_x shall be a promising CBL for high-performance inverted PVSCs and inspire the further applications of quaternary ammonium functionalized MXenes in PVSCs.     

手持终端设备主备电池控制系统设计

手持终端设备属于一种嵌入式系统,特别在工业应用领域对其供电持续性的要求很高。为了解决单电池供电下设备续航能力不足导致传输数据丢失的问题,本文设计一种主备电池控制系统,提高了整机的续航能力和电源系统的可靠性。方案设计对切换灵敏度、功耗和可靠性方面进行了综合考虑,已经应用到实际产品中,取得了良好的效果。