A Low-Power Wide-Dynamic-Range Analog VLSI Cochlea

Low-power wide-dynamic-range systems are extremely hard to build. The biological cochlea is one of the most awesome examples of such a system: It can sense sounds over 12 orders of magnitude in intensity, with an estimated power dissipation of only a few tens of microwatts. In this paper, we describe an analog electronic cochlea that processes sounds over 6 orders of magnitude in intensity, and that dissipates 0.5 mW. This 117-stage, 100 Hz to 10 KHz cochlea has the widest dynamic range of any artificial cochlea built to date. The wide dynamic range is attained through the use of a wide-linear-range transconductance amplifier, of a low-noise filter topology, of dynamic gain control (AGC) at each cochlear stage, and of an architecture that we refer to as overlapping cochlear cascades. The operation of the cochlea is made robust through the use of automatic offset-compensation circuitry. A BiCMOS circuit approach helps us to attain nearly scale-invariant behavior and good matching at all frequencies. The synthesis and analysis of our artificial cochlea yields insight into why the human cochlea uses an active traveling-wave mechanism to sense sounds, instead of using bandpass filters. The low power, wide dynamic range, and biological realism make our cochlea well suited as a front end for cochlear implants.     

A study on microstructure and properties of calcium phosphate coatings processed using ion beam assisted deposition on heated substrates

In this study a set of thin Hydroxyapatite (HA) [Ca₁₀(PO₄)₆(OH)₂] coatings was deposited on heated silicon and titanium substrates using Ion Beam Assisted Deposition (IBAD). The effects of substrate temperature and processing parameters on the microstructural properties and composition of the coatings are being studied. Analytical techniques include transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM) with an energy dispersive X-ray spectroscopy (EDS), as well as scanning electron microscopy (SEM) with EDX, X-ray diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR). The current results indicate that as substrate temperature increases the Ca/P ratio of the coatings both on titanium and silicon substrates increases. The crystallinity of the coatings and the number of calcium phosphate compounds within the coating including HA also increases. STEM-EDS revealed an atomically diffused intermediate layer at the interface between the coating and substrate. XRD results along with TEM selected area diffraction (SAD) revealed that the coatings are composed of HA, other calcium phosphate, and calcium oxide compounds.     

Thick bone section preparation using a silicon-rubber-based sealant

A method has been developed, using a silicon-rubber-based sealant, which allows 2–3-mm-thick specimens to be maintained in a protected fluid environment for a number of months, without risk of dehydration. Following this, the specimen can be retrieved, stained, embedded and sectioned further. For example, 2-mm-thick sections of fixed unstained bone are easily examined by means of epi-illuminated polarized light and fluorescence microscopies using either conventional or confocal optics. The method could easily be extended to other tissues, for example brain tissue.     

The T Cell Repertoires from Nickel Sensitized Joint Implant Failure Patients

Nickel (Ni²⁺) is one of the most common allergens, affecting around 10–15% of the general population. As the demand for orthopedic implant surgery rises, the number of surgical revisions due to joint implant failure also increases. There is evidence that some patients develop joint failure due to an immune response to a component of the implant, and we have found that Ni²⁺ is an especially important cause. Hence, understanding the mechanisms by which Ni²⁺ allergy induces joint implant failure becomes a critical research question. The structural basis of Ni²⁺ activation of pathogenic T cells is still not clear. The purpose of this study was to characterize Ni²⁺-reactive T cell repertoires derived from the peripheral blood of joint failure patients due to Ni²⁺ sensitization using single-cell sequencing techniques. We stimulated the proliferation of Ni²⁺ -reactive T cells from two implant failure patients in vitro, and sorted them for single-cell VDJ sequencing (10× genomics). We identified 2650 productive V-J spanning pairs. Both TCR α chains and β chains were enriched. TRBV18 usage is the highest in the P7 CD4+ population (18.1%), and TRBV5-1 usage is the highest in the P7 CD8+ population (12.1%). TRBV19 and TRBV20-1 segments are present in a high percentage of both P7 and P9 sequenced T cells. Remarkably, the alpha and beta chain combination of TRAV41-TRBV18 accounts for 13.5% of the CD4+ population of P7 patient. Compared to current Ni specific T cell repertoire studies of contact dermatitis, the Vα and Vβ usages of these joint implant failure patients were different. This could be due to the different availability of self-peptides in these two different tissues. However, TRBV19 (Vβ17) was among frequently used TCR β chains, which are common in previous reports. This implies that some pathogenic T cells could be similar in Ni²⁺ hypersensitivities in skin and joints. The alignment of the TCR CDR3β sequences showed a conserved glutamic acid (Glu) that could potentially interact with Ni²⁺. The study of these Ni²⁺ specific TCRs may shed light on the molecular mechanism of T cell activation by low molecular weight chemical haptens.     

增加电极位置信息的电子耳蜗听觉仿真模型

为了改进以正弦信号合成的电子耳蜗听觉仿真模型在仿真电子耳蜗植入患者所感知的语音信息的缺陷,建立了增加电极位置信息的正弦信号合成的听觉仿真模型.通过大样本量的不同汉语语言材料的听觉仿真实验,其中包括按元音、辅音、数字、音调和单字词等5种汉语语言材料,研究了基于连续交叉采样算法的不同实验条件下电极位置对言语识别率的影响,得出了汉语元音和单字词对植入深度更加敏感的结论.为进一步将这一仿真模型应用到电子耳蜗研究上奠定了基础.     

应力/应变场对插销试验焊接接头氢扩散的影响

采用ABAQUS有限元分析软件及有关焊接接头中氢扩散与集聚的计算模拟技术计算分析了不同外加载荷条件下插销试件的能力、应变场及其对氢扩散与聚集过程的影响。计算结果表明，静载拉伸条件下插销缺口前沿有明显的应力应变集中，随着外加载荷的增加，缺口尖端应力逐渐增大，但应力集中系数逐渐减小；在相同初始氢条件下，随着外加载荷的增加，缺口前沿应力应变集中部位氢的峰值浓度逐渐提高，氢浓度达到峰值的时间也逐渐增长。分析认为，插销缺口附近产生的应力应变集中是导致氢在该区域产生聚集的重要原因。     

数据采集与变频调速在插销裂纹试验机上的应用

针对插销裂纹试验机加裁过程波动大，影响试验结果的问题，利用数据采集技术记录插销所经历的热循环和裁荷历程，通过采集卡的数字输出通道控制继电器的通断，从而改变变频器的输出电压相位，达到控制插销试验机电机转向的目的；对于试验过程中给定的载荷设定值，系统根据等比关系将其模糊化成几个区间，并确定当前采集到的载荷的所在区间，根据区间的不同，赋予采集卡的模拟输出通道一变化电压值，将其输出到变频器，最终控制电动机的转速。试验结果表明，加载过程实现了自动化和平稳化，并且在栽荷设定值处没有超调量。     

应用RFID技术实现医用植入装置的通信

典型的医用植入装置由体外部分和植入体两部分组成,二者之间通过射频载波传输能量和信息,这与广泛应用的射频识别技术非常相似。本文分析研究了它们在技术和应用层面的特点,提出了一种基于商用RFID技术及其器件实现的医用植入装置双向通信的设计,对于具体实现过程中的关键技术、必要的技术裁剪和技术扩展进行了较为详细的介绍。     

中束流离子注入机工艺实现原理

粒子高速冲击其他材料并进入其中叫作离子注入。在半导体工业中,这个过程用来向纯净衬底上掺杂杂质而形成半导体。半导体工艺中这个特别的步骤是由一种特殊的粒子加速装置完成,这就是离子注入机。