Vero细胞在微载体上迁移和多层生长现象

本文通过对电子显微镜观察了Ｖｅｒｏ细胞有微载体增减过程中的迁移民政部发现在不同增减阶段，Ｖｒｏ细胞迁移方式不同；在分泌形成的细胞外基质，上，Ｖｅｒｏ细胞迁移是通过 层粘连蛋白介导进行的，被层粘连蛋白抗体抑制；这种迁移导致Ｖｅｒｏ细胞在微载体上形成多层生长现象。     

凸非球面补偿检验的工艺球面分析解

本文从三级像差理论出发,推导了几种工艺球面检验凸二次曲面的计算公式。根据这些公式计算结果,进行了光路追迹,给出了这些公式对凸二次曲面的补偿范围;并讨论了几种特殊情况下的平面解。     

Development of enhanced depth-resolution technique for shallow dopant profiles

A rapid shrinkage in the minimum feature size of integrated circuits requires analysis of dopants in their shallow source–drain and their extensions with an enhanced depth resolution. Rutherford backscattering spectroscopy (RBS) combining a medium-energy He ion beam with a detector of improved energy resolution should meet the requirement of a depth resolution better than 5 nm at a depth of 10–20 nm in the next 10 years. A toroidal electrostatic analyzer of 4×10⁻³ energy resolution has been used to detect the scattered ions of a medium-energy He ion beam. Five keV As⁺ implanted Si or SiO₂ samples were measured. Depth profiling results using the above technique are compared with those of glancing-angle RBS by MeV energy He ions. Limitations in the energy resolution due to various energy-spread contributions have been clarified.     

Damage and strain in pseudomorphic vs relaxed GexSi1−x layers on Si(100) generated by Si ion irradiation

We compare both the strain and damage that 100 keV Si irradiation at room temperature introduces in pseudomorphic and relaxed Ge_xSi_1−x films grown on Si(100) substrates. The ion range is such that the Si/Ge_xSi_1−x interface is not significantly damaged. The amount of damage produced in pseudomorphic and relaxed Ge_xSi_1−x layers of similar x for irradiation doses up to 2.5 × 10¹⁴ Si/cm² is the same, which proves that a pre-existing uniform strain does not noticeably affect the irradiation-induced damage. However, the irradiation-induced strain does depend on the pre-existing strain of the samples. Possible interpretations are discussed. On leave from Inst. voor Kern en Stralingsfysika, Catholic University of Leuven, Belgium.     

一种低压低功耗SRAM/SOI单元设计

提出一种改进4管自体偏压结构SRAM/SOI单元.基于TSUPREM4和MEDICI软件的模拟和结构性能的分析,设计单元结构并选取结构参数.该结构采用nMOS栅下的含p+埋沟的衬底体电阻代替传统6管CMOSSRAM单元中的pMOS元件,具有面积小、工艺简单的优点.该结构可以在0.5V的电源电压下正常工作,与6管单元相比,该单元瞬态响应正常,功耗只有6管单元的1/10,满足低压低功耗的要求.     

Charge transfer resistance of spray deposited and compressed counter electrodes for dye-sensitized nanoparticle solar cells on plastic substrates

Electrochemical impedance spectroscopy was used to determine the effective charge transfer resistances of porous dye-sensitized solar cell counter electrodes prepared by low-temperature spray deposition and compression of conductive carbon and platinized Sb-doped SnO₂ powders on indium tin oxide-coated plastic substrates. The charge transfer resistances were 0.5–2 and 8–13 Ω cm², respectively, when using 3-methoxypropionitrile as the electrolyte solvent. The manufacturing method used lends itself to produce mechanically stable and even-quality electrodes in an easy and fast manner.     

Promising alloys for intermediate-temperature solid oxide fuel cell interconnect application

The formation of a low Cr-volatility and electrically conductive oxide outer layer atop an inner chromia layer via thermal oxidation is highly desirable for preventing chromium evaporation from solid oxide fuel cell (SOFC) metallic interconnects at the SOFC operation temperatures. In this paper, a number of ferritic Fe–22Cr alloys with different levels of Mn and Ti as well as a Ni-based alloy Haynes 242 were cyclically oxidized in air at 800 °C for twenty 100-h cycles. No oxide scale spallation was observed during thermal cycling for any of these alloys. A mixed Mn₂O₃/TiO₂ surface layer and/or a (Mn, Cr)₃O₄ spinel outer layer atop a Cr₂O₃ inner layer was formed for the Fe–22Cr series alloys, while an NiO outer layer with a Cr₂O₃ inner layer was developed for Haynes 242 after cyclic oxidation. For the Fe–22Cr series alloys, the effects of Mn and Ti contents as well as alloy purity on the oxidation resistance and scale area specific resistance were evaluated. The performance of the ferritic alloys was compared with that of Haynes 242. The mismatch in thermal expansion coefficient between the different layers in the oxide scale was identified as a potential concern for these otherwise promising alloys.     

Shallow hydrogen-induced donor in monocrystalline silicon and quantum wires

Electrical and optical properties of bistable shallow donors in monocrystalline silicon, which are introduced by proton implantation followed by annealing at 450 °C, have been studied. The temperature dependences of equilibrium and non-equilibrium carrier concentration and relaxation kinetics were investigated. IR absorption lines of bistable shallow donor electronic excitations were detected. The obtained experimental data demonstrate that the bistable shallow donors can be identified as quantum wire defect nanoclusters.     

An extension of the Secant Method for the homogenization of the nonlinear behavior of composite materials

We discuss the consequences of a different application of the principle the Modified Secant Method is [C. R. Acad. Sci. Paris Sér. IIb 320 (1995) 563] based on. In fact, we directly compute the second-order averages of the local fields available from the linear elastic homogenization procedure exploited in order to evaluate the effective elastic moduli. This method, which can be seen either as a simplification of the Modified Secant Method or as an extension of the Secant Method [J. Mech. Phys. Solids 26 (1979) 325], may be useful for any composite whose overall elastic constants need to be estimated by modeling the microstructure through Morphologically Representative Patterns [J. Mech. Phys. Solids 44 (1996) 307], which is for instance the case of syntactic foams [Int. J. Solids and Structures 38/40-41 (2001) 7235]. In order to show the accuracy of the proposed method, we apply it to several examples and compare its results with those obtainable by means of other analytical methods available in the literature, with numerical results of Finite Element simulations, and with experimental results. Closed-form solutions are derived for the effective yield stress of porous metals and incompressible composites reinforced with rigid spheres.