The optimal condition for H<Subscript>2</Subscript>TiO<Subscript>3</Subscript>–lithium adsorbent preparation and Li<Superscript>+</Superscript> adsorption confirmed by an orthogonal test design

An orthogonal test design was applied to confirm the optimum condition for H₂TiO₃–lithium adsorbent preparation and Li⁺ adsorption. Extraction and adsorption mechanism and cycle performance were studied. The verified optimal condition is confirmed as the Li⁺ concentration, adsorption temperature, molar ratio of Li/Ti, reaction, and pre-calcination temperature are 4.0 g L^?1, 60 °C, 2.2, and 650 and 25 °C, respectively. Under the optimal condition, the adsorptive capacity reaches 57.8 mg g^?1. Adsorptive capacity of the adsorbent maintains in 5 cycles, typically 25–30 mg g^?1.     

Interactions and Encapsulation of Vitamins C,B3, and B6 with Dendrimers in Water

Titrations of commercial diaminobutane (DAB) and polyamidoamine (PAMAM) dendrimers by vitamins C (ascorbic acid, AA), B₃ (nicotinic acid), and B₆ (pyridoxine) were monitored by ¹H NMR spectroscopy using the chemical shifts of both dendrimer and vitamin protons and analyzed by comparison with the titration of propylamine. Quaternarizations of the terminal primary amino groups and intradendritic tertiary amino groups, which are nearly quantitative with vitamin C, were characterized by more or less sharp variations (Δδ) of the ¹H chemical shift (δ) at the equivalence points. The peripheral primary amino groups of the DAB dendrimers were quaternarized first, but not selectively, whereas a sharp chemical‐shift variation was recorded for the inner methylene protons near the tertiary amines, thereby indicating encapsulation, when all the dendritic amines were quaternarized. With DAB‐G5‐64‐NH₂, some excess acid is required to protonate the inner amino groups, presumably because of basicity decrease due to excess charge repulsion. On the other hand, this selectivity was not observed with PAMAM dendrimers. The special case of the titration of the dendrimers by vitamin B₆ indicates only dominant supramolecular hydrogen‐bonding interactions and no quaternarization, with core amino groups being privileged, which indicates the strong tendency to encapsulate vitamins. With vitamin B₃, a carboxylic acid, titration of DAB‐G3‐16‐NH₂ shows that only six peripheral amino groups are protonated on average, even with excess vitamin B₃, because protonation is all the more difficult due to increased charge repulsion, as positive charges accumulate around the dendrimer. Inner amino groups interact with this vitamin, however, thus indicating encapsulation presumably with supramolecular hydrogen bonding without much charge transfer.     

基于LabVIEW的存储器检测系统研究

针对某装备的存储器没有相应的测试设备,测试内容比较繁琐,设计了基于LabVIEW的存储器检测系统.硬件依托PXI测试总线予以实现,具有可靠性高,灵活性强的特点.针对组合存储器的特点,设计了专用的接口适配器,主要用于实现信号的同步和调理.文中分析了存储器的故障类型,研究March算法并进行了扩展.系统以LabVIEW作为软件工具,实现了对存储器的自动测试,用数据库实现了测试算法与测试程序的分离.该系统具有操作容易,可扩展性强等特点,有效提高了对某装备存储器的测试效率.     

一种高线性度14位40 MS/s流水线A/D转换器

设计了一个14位40 MHz、100 dB SFDR、1.8 V电源电压的流水线A/D转换器(ADC).采用增益自举密勒补偿两级运放,可在保证2 Vpp差分输出信号摆幅的前提下获得130dB的增益,有效地减小了运放有限增益的影响;同时,采用冗余位编码技术和动态比较器,降低了比较器失调电压的设计难度和功耗.该设计采用UMC 0.18 μm CMOS工艺,芯片面积为2mm×4 mm.仿真结果为:输入满幅单频9 MHz的正弦信号,可以达到100 dB SFDR和83.8 dBSNDR.     

一种用于音频系统的1.1mW 87dB动态范围的ΔΣ调制器

本文描述了一款应用于音频系统的1.1mW 87dB动态范围的 Delta-Sigma 调制器的设计,设计采用0.18um CMOS工艺。由于采用带有前馈支路的多比特结构,第一级积分器的输出摆幅得到有效压缩。第一级积分器采用结构简单,直流增益仅34dB,工作在1V电压下的电流镜型跨导放大器。在3KHz信号输入下,该调制器可在100Hz~24KHz的频率范围内达到83.8dB的峰值SNDR和87dB的动态范围。     

A low power 8-bit successive approximation register A/D for a wireless body sensor node

A power efficient 8-bit successive approximation register(SAR)A/D for the vital sign monitoring of a wireless body sensor network(WBSN)is presented.A charge redistribution architecture is employed.The prototype A/D is fabricated in 0.18 μm CMOS.The A/D achieves 7.SENOB with sampling rate varying from 64 kHz to 1.5 MHz.The power consumption varies from 10.8 to 225.7 μW.     

All-Polymer Fiber Organic Electrochemical Transistor for Chronic Chemical Detection in the Brain

Continuous and precise monitoring of chemicals in the brain can assist in understanding the working mechanism of the brain and exploring therapeutics for nerve disorders. Organic electrochemical transistors (OECTs) are employed for this purpose due to their high sensitivity from the in situ amplification effect. However, the chronic and stable detection of chemicals in the brain is rarely reported for OECTs. It is possibly due to the chronic inflammation from mechanical mismatch between the device and soft brain tissue as well as the biofouling that hinder the diffusion of chemicals to decrease the sensitivity similar to other implanted devices. Therefore, an all-polymer fiber OECT (PF-OECT) is designed, composed solely of conductive polymers and fluorine rubber. The PF-OECT shows matching modulus with the soft brain tissue and good anti-biofouling performance. It also demonstrates both high sensitivity and electrochemical stability under dynamic deformations and in complex protein solutions. Finally, the PF-OECT is implanted into the mouse brain, achieving a stable 14-day ascorbic acid monitoring. The design strategy of PF-OECT presents a potential avenue for developing more biomedical devices.     

基于MATLAB App技术的“数字信号处理”“信号与系统”的可视化教学研究

文中根据民办应用型大学的教学要求,针对“数字信号处理”“信号与系统”两门电子类专业基础课公式多、概念抽象、内容交叉较多的特点,利用MATLAB App Designer 设计了虚拟仿真实验平台,整合了优化课程知识,同时将“工程观”融入课程中,将理论知识与工程实际相联系,增强了学生综合分析和解决问题的能力。     

微波炉溶样法在测定饲料中的汞中的应用

用微波炉溶样处理饲料样品,再淫测汞仪测定其中的汞,比用回流消化法快速、简便,加标回收率为９７．３％￣９８．３％,结果准确可靠。