Factors affecting lactoperoxidase activity

The extent to which lactoperoxidase (LP) activity was affected while varying the concentration of various compounds normally present in the reaction medium was investigated. LP activity increased with increasing concentrations of 2,2'-azino-bis-3-ethylbenz-thiazoline-6-sulphonic acid (ABTS) but decreased with increasing thiocyanate concentrations. Maximum activity was at 0.1 mm for peroxide. Activity increased in the presence of lactose, whey protein concentrate, sodium, magnesium and calcium chlorides, but decreased in the presence of casein. Activity was similar in either acetate or phosphate buffers but higher in either citrate or succinate buffers. These compounds influence LP activity and should be considered when optimum activity conditions are being established.     

Microwave dielectric properties of Ba3Ti4−x(Zn1/3Nb2/3)xNb4O21 for low temperature co-fired ceramics

The effects of substitution of (Zn_1/3Nb_2/3) for Ti on the sintering behavior and microwave dielectric properties of Ba₃Ti_4−x(Zn_1/3Nb_2/3)_xNb₄O₂₁ (0 ≤ x ≤ 4) ceramics have been investigated. The dielectric constant (?_r) and the temperature coefficient of the resonant frequency (τ_f) of Ba₃Ti_4−x(Zn_1/3Nb_2/3)_xNb₄O₂₁ ceramics decreased with increasing x. However, the Q × f values enhanced with the substitution of (Zn_1/3Nb_2/3) for Ti. It was found that a small amount of MnCO₃-CuO (MC) and ZnO-B₂O₃-SiO₂ (ZBS) glass additives to Ba₃Ti_4−x(Zn_1/3Nb_2/3)_xNb₄O₂₁ (x = 2) ceramics lowered the sintering temperature from 1250 to 900 °C. And Ba₃Ti_4−x(Zn_1/3Nb_2/3)_xNb₄O₂₁ (x = 2) ceramics with 1 wt% MC and 1 wt% ZBS sintered at 900 °C for 2 h showed excellent dielectric properties: ?_r = 53, Q × f = 14,600 GHz, τ_f = 6 ppm/°C. Moreover, it has a chemical compatibility with silver, which made it as a promising material for low temperature co-fired ceramics technology application.     

不同金属基底改性Zn负极的电化学性能研究

将经过熔炼、锻造、打磨和抛光的金属Ni、Cu、Sn、In、Ti作为Zn负极的基底,制备了水系Zn离子电池。运用XRD、SEM、原位光学显微镜和电化学表征技术,分析了不同基底上的析氢速率、Zn在不同基底上的沉积/溶解行为、电偶腐蚀程度以及循环性能。结果表明,Sn和In不仅能够抑制Zn与基底之间引起的副反应,而且具有优异的亲Zn性能,但Zn在Sn基底表面沉积的形貌受Sn晶面的影响较大,In更适宜用作Zn负极的基底。     

A novel method for the fabrication of freestanding PZT features on substrates

A simple and cheap micromoulding fabrication route was developed to prepare freestanding piezo active features. Dimensions as small as 200 μm by 200 μm and 40 μm high were successfully fabricated via a replication technique. The lead zirconate titanate features were thoroughly characterized using SEM, EDX and XRD analysis. The properties of the features were influenced by several factors like the type of substrate, sintering temperature and sintering atmosphere. Features prepared on alumina substrates and sintered in lead atmosphere displayed a structure with reproducible dimensions. Next to that they were low in porosity and had a comparable composition with respect to the starting powder. The remanent polarization of the lead zirconate film was 12.3 μC/cm² and the coercive field was 8.7 kV/cm.     

Study of cr,si and mn distribution in semi-insulating gaas after annealing with and without SiO2 in an H2-AS4 atmosphere

We compare the chemical distribution of Cr, Mn, Fe and Si and electrical profiles in implanted semi-insulating substrates annealed with and without a SiO₂ encapsulant in a H₂-AS₄ atmosphere. The implantation energy and dose are appropriate for medium power FET applications. Excellent correlation between electrical and chemical profiles have been obtained from charge neutrality considerations. Mn and Cr chemical redistribution profiles are studied as a function of annealing temperature. The Hall mobilities at liquid nitrogen temperature are correlated to the N_AN_D ratio for different methods of annealing.     

The influence of tetrahedral ordering on the microwave dielectric properties of Sr0.05Ba0.95Al2Si2O8 and (M = Al, Ga, M′ = Si, Ge) ceramics

The feldspars Sr_0.05Ba_0.95Al₂Si₂O₈, BaAl₂Ge₂O₈ and BaGa₂Si₂O₈ with S.G. I2/c, and BaGa₂Ge₂O₈ with S.G. P2₁/a, were studied by means of crystal structural and microstructural analyses and dielectric measurements. All the investigated densely sintered single-phase feldspars exhibited a permittivity () of 7–8 and a temperature coefficient of resonant frequency (τ_f) from −20 to −30 ppm/°C. In contrast to the and τ_f the dielectric losses were found to be dependent on the annealing conditions. In Sr_0.05Ba_0.95Al₂Si₂O₈ the Qxf values increased from 42,500 to 92,600 GHz when the annealing time at 1400 °C was increased from 1 to 162 h. Such a difference in the Qxf values as a result of various annealing conditions was attributed to different degrees of tetrahedral ordering. In contrast to aluminosilicate feldspars, Ge-containing feldspars can be sintered and ordered at low temperature. In BaAl₂Ge₂O₈ the Qxf values decreased when the sintering temperature exceeded the order-disorder I2/c ↔ C2/m phase-transition temperature. The BaGa₂Si₂O₈ and BaGa₂Ge₂O₈ feldspars exhibited a rapid decrease of Qxf values when the annealing temperature approached the melting point. However, the BaAl₂Ge₂O₈ and BaGa₂Ge₂O₈ can regain their high Qxf values by annealing at 1000 °C. The BaGa₂Ge₂O₈ stood out from the other investigated feldspars, with a sintering temperature of 1100 °C, Qxf values of 100,000–150,000 GHz and a τ_f of −26 ppm/°C.     

Development of Nano-tetragonal Zirconia-Incorporated Ni–P Coatings for High Corrosion Resistance

Pure tetragonal 10-20-nm-size zirconia-based Ni-P composite coating was developed. The physicochemical and electrochemical characteristics including corrosion resistance of the coating were investigated. The Ni-P-nano-tetragonal zirconia coating was partially crystalline having face-centered cubic phase. The coating had very high corrosion resistance due to its dense compact morphology and low surface roughness. The Ni-P-nano-tetragonal zirconia coatings exhibited a cathodic shift of open-circuit potential(OCP) in the range from-0.340 to-0.520 V. A high polarization resistance of the order of 13.2 kΩ/cm~2 and low corrosion current density of 3.9 μA/cm~2 were achieved due to the effective incorporation of zirconia into the coating.     

延长高能LED产品使用寿命的绝缘金属基板简介

发光二极管在产生可见光的同时也产生大量的热量。如果使用不当,这些热量会导致电子产品过早地损坏。绝缘金属基板可以解决该问题,同时延长这些产品的使用寿命。     

焊球阵列转变与绝缘基板技术

在半导体整体的焊球阵列封装(BGA)领域,一份针对数个关键封装形式所进行的分析报告中,显示了造成不同焊球阵列封装形式成长或下跌的原因,并更清楚地点出了目前使用的数种基板技术的缺点。这篇分析报告列出了主要的焊球阵列封装的形式和基板发展潮流,还清楚地指出焊球阵列封装整体的发展延缓了硅芯片技术的演进,这在某些BGA领域中尤其明显,主要是因为缺乏先进的基板技术。因此文后得出结论,封装产业供货供应链基板市场中可能出现新的厂商,其也许来自主机板市场。     

Germanium on sapphire substrates for system on a chip

Germanium on sapphire (GeOS) is proposed for system on a chip applications. Sapphire substrates are demonstrated to exhibit lower rf losses and superior crosstalk suppression compared with oxidised silicon handle wafers. Inductors on sapphire also show higher quality factor and better frequency response than those manufactured on an SOI platform. GeOS substrates have been manufactured by wafer bonding. Bond strengths of greater than 2900 mJ m⁻² have been obtained. Thin GeOS has been achieved by He/H₂ ion cut processes. A self-aligned W gate process on Ge has been established with processing temperature limited to 400 °C. P channel MOSTs exhibit low threshold voltage and a carrier mobility of about 400 cm² V⁻¹ s⁻¹.