一种无源植入式神经刺激器中模拟前端的设计

设计了一种可应用于超高频无源植入式神经刺激器的模拟前端电路。对无源植入式芯片模拟前端的系统架构进行了论述,简述了前端架构中各个模块的工作原理,通过优化系统结构,减小了系统复杂度和版图面积。模块包括整流电路、电源管理电路、调制解调电路、上电复位电路和时钟产生电路。其中,整流电路工作时,效率可达到45%以上,并且能提供两种不同的工作电压。使用Cadence Spectre对设计电路进行仿真,并通过TSMC 0.35 μm BCD工艺进行流片验证。结果显示,该模拟前端的直流功耗为0.06 mW,芯片面积为0.4 mm²,可以满足植入式神经刺激器的要求。     

基于简单随机抽样的大数据可信性验证方法

针对大数据的可信性验证问题,本文提出了一种大数据可信性验证方法以验证数据来源和数据内容的可信性.本文首先通过验证数据属主的身份证书来实现数据来源可信性的验证,再在简单随机抽样和可聚合的广播签名方案的基础上,设计了一个交互式质询-应答协议,使得用户只需抽样少量数据就能以高置信率验证数据内容的可信性.理论分析和实验结果表明,本文方法是安全的,且性能开销在合理范围内,能够实现大数据的可信性验证.     

Pyrylium‐based dye and charge tagging in proteomics

The pyrylium group is a selective reagent for ε‐amino groups in proteins. In particular, for fluorescence labeling, a number of advantages over traditional N‐hydroxysuccinimidyl ester chemistry were recognized such as the rapid prestaining procedure. Here, we have investigated the labeling reaction for the fluorogenic pyrylium dye Py‐1 using liquid chromatography coupled to MS with the aim of determining its specificity and possible side products. Peptides containing no, one, and two lysine residue and a choice of no or one cysteine residue were labeled with Py‐1 at yields > 30%. Gas phase fragmentation proved both labeling of lysine residues as well as that of the N‐terminus also in peptides that contained a lysine residue. Evidence for cysteine labeling was not found, but several other products were detected such as the results of rearrangements with adjacent acidic amino acids. Apart from the use as a fluorogenic label, Py‐1 recommends itself for N‐terminal charge tagging as alternative to the commonly used quaternary ammonium salts. Predominantly a‐ and b‐type ion series were observed for N‐terminally labeled peptides. Further applications include chromophore tagging since the labeled product is not only fluorescent but also colored red.     

Fixation of XAD-4 power on filter paper using methyl cellulose for the passive air sampling of semi-volatile organic compounds in indoor air

The sorption capacity of a substrate serving as sampling medium can be enhanced by adding another sorbent to its surface. This is usually achieved through an impregnation process by repeated dipping of the substrate in a slurry solution containing the powder of the sorbent. Because the impregnation process only deposits the sorbent powder on the surface of the substrate, the powder could detach and fall off during field deployment. In this study, a novel approach was explored to fix the added sorbent powder to the surface of the substrate. Methylcellulose (MC) in fine crystal form was selected as the fixing agent to secure the powder of polystyrene-divinyl benzene copolymer resin (XAD-4), with its high sorption capacity, to a cellulose filter paper (CFP). The process involved first mixing XAD-4 and MC in the presence of water to form a milky slurry solution that was then painted on to the surface of the paper and then allowed to dry. The painting technique resulted in a good reproducibility of the applied amount of XAD-MC mixture with a relative standard deviation (RSD) of 12% (n = 5). Scanning electron microscope (SEM) images showed that the XAD-4 powder was held to the surface of the filter paper. No free XAD powder was dislodged from the coated filter paper when coated paper was flicked with a finger. For use as an indoor passive air sampler (PAS), this new sampling medium was placed in a round housing made of electronically polished aluminium material and was tested for uptake of polybrominated diphenyl ethers and phthalic acid dialkylesters. Surface area specific uptake rates (ASUR) of PBDEs ranged from 1.14 to 2.82 m³/(dm²d), while ASUR of phthalates had a wider range from 2.74 to 5.66 m³/(dm²d).     

Inertial cavitation initiated by polytetrafluoroethylene nanoparticles under pulsed ultrasound stimulation

Nanoscale gas bubbles residing on a macroscale hydrophobic surface have a surprising long lifetime (on the order of days) and can serve as cavitation nuclei for initiating inertial cavitation (IC). Whether interfacial nanobubbles (NBs) reside on the infinite surface of a hydrophobic nanoparticle (NP) and could serve as cavitation nuclei is unknown, but this would be very meaningful for the development of sonosensitive NPs. To address this problem, we investigated the IC activity of polytetrafluoroethylene (PTFE) NPs, which are regarded as benchmark superhydrophobic NPs due to their low surface energy caused by the presence of fluorocarbon. Both a passive cavitation detection system and terephthalic dosimetry was applied to quantify the intensity of IC. The IC intensities of the suspension with PTFE NPs were 10.30 and 48.41 times stronger than those of deionized water for peak negative pressures of 2 and 5 MPa, respectively. However, the IC activities were nearly completely inhibited when the suspension was degassed or ethanol was used to suspend PTFE NPs, and they were recovered when suspended in saturated water, which may indicates the presence of interfacial NBs on PTFE NPs surfaces. Importantly, these PTFE NPs could sustainably initiate IC for excitation by a sequence of at least 6000 pulses, whereas lipid microbubbles were completely depleted after the application of no more than 50 pulses under the same conditions. The terephthalic dosimetry has shown that much higher hydroxyl yields were achieved when PTFE NPs were present as cavitation nuclei when using ultrasound parameters that otherwise did not produce significant amounts of free radicals. These results show that superhydrophobic NPs may be an outstanding candidate for use in IC-related applications.     

基于COM模型的伪正交频率编码S因子的优化

综合考虑反射栅阵列相关性和频带利用率,对设计的伪正交频率编码(POFC)系统选取合适的频率间隔因子——S因子。论述了正交频率编码(OFC)和POFC的基本原理;对POFC系统的耦合模(COM)模型进行分析,推导出相邻中心频率间的互相关函数,对不同S因子下互相关函数峰值进行提取、散点图分析和分段数值拟合。以此找到该POFC系统合理的S因子取值区间:[1.49,1.83]、[2.1,2.63]和[3.12,3.415],从而进行建模分析及信息提取,为POFC系统的设计提供借鉴。     

Built-in ESD Protection for RFID Tag ICs

The built-in Electro-Static discharge (ESD) protection circuits for Radio frequency identification (RFID) tag ICs are proposed.The ESD protection function is built into the rectifier and amplitude limiter.The rectifier and limiter are connected directly to the RF interface,and some transistors can discharge the larger current.These transistors can be used to build ESD protection circuits,through the redesign and optimization.The built-in ESD protection circuits can improve the ESD protection level and reduce the layout area.The circuits have been fabricated in 0.18μm CMOS process.The test results show that the built-in ESD protection circuits work well under 4kV ESD pressure and save as much as 72％ of the layout area compare with foundry standard ESD protection cells.     

Fluorous analogues of DMAP (F-DMAP): Reusable organocatalysts for acylation reaction

A short and facile preparation of analogues of DMAP (F-DMAPs) labelled with fluorous chains is reported. These catalysts efficiently promote the acylation of alcohols with anhydrides (Ac₂O, (i-PrCO)₂O) and can be partially recovered and reused. The effectiveness of F-DMAP is similar to that of DMAP.     

Ennoblement of stainless steel in the presence of glucose oxidase: nature and role of interfacial processes

The ennoblement of the free corrosion potential (E(corr)) of AISI 316L stainless steel which did not occur in synthetic fresh water (SFW), was observed after introduction of glucose oxidase (Gox) and glucose, or of hydrogen peroxide (H(2)O(2)). The composition of the surface was monitored using AFM and XPS, a detailed XPS analysis being based on the discrimination between oxygen of organic and inorganic nature proposed in a previous study. In H(2)O(2) medium, the main changes regarding the inorganic phase were the increase of the oxygen concentration in the passive film, the increase of the molar concentration ratio of oxidized species Fe(ox)/Cr(ox) and the growth of nanoparticles, presumably made of ferric oxide/hydroxide. In Gox medium, no significant changes were observed in both oxygen concentration and Fe(ox)/Cr(ox) ratio, but the density of colloidal particles decreased, indicating a dissolution of Fe oxide/hydroxide under the influence of gluconate. In contrast with H(2)O(2), in SFW and Gox the amount of organic compounds increased due to the accumulation of polysaccharides and proteins. The influence of glucose oxidase on the ennoblement of stainless steel is not due to indirect effects of H(2)O(2) through the change of surface composition. The E(corr) ennoblement seems to be directly due to the presence of H(2)O(2) and to the electrochemical behavior of H(2)O(2) and related oxygen species. This consideration is important for understanding and controlling microbial influenced corrosion.     

FTIR被动遥测信噪比优化及在变电站SF6泄漏检测应用

被动FTIR红外遥测技术可应用于气体泄漏检测,气体检测下限与仪器信噪比密切相关。仪器信噪比与测量参数有关,如光谱分辨率、采样频率、积分时间、平均次数等,如何结合实际应用优化参数组合以实现最佳信噪比,目前还缺少系统分析。针对这一问题,从理论上分析了这些参数与信噪比关系,并归类为三个方面：（1）光谱分辨率,引用了Roland Harig给出的结论,当光谱分辨率低于特征峰半高全宽时,信噪比不变,但为了避免背景气体的交叉干扰,分辨率不宜设置过低,需要结合实际应用综合考虑;（2）降低采样频率能够减少计算量,缩小光谱范围,但采样频率和光谱范围与信噪比无关;（3）在积分时间和光谱平均次数方面,同样时间条件下,多次干涉图采集会引入零光程差的采样误差,使得噪声大于理论计算值,因而长积分时间获得信噪比优于多次平均。开展了六氟化硫（SF₆）泄漏检测实验,根据SF₆特征峰宽度选择4 cm-1分辨率,20 kHz采样频率兼顾了信噪比和检测时间,并利用FTIR巡检系统发现变电站泄漏点,证明了方法的有效性。