磁电子学的应用进展

把磁性元件和电子学元件结合起来的磁电子学器件,已开始出现实验室和商业化产品。本文介绍了磁电子学在计算机读出磁头,随机存取存储器,磁传感器,自旋晶体管和自旋阀晶体管中的应用,描述了它们的工作原理,性能特点及研究现状和发展趋势。     

ULVAC research and development of Cat-CVD applications

This paper reports the feasibility for industrial implementation of Cat-CVD (Hot-Wire CVD) technology. Some application examples are shown, and their features and problems are described. Cat-CVD is a unique technology which has a lot of possibilities. Some of them will be commercialized in the near future, but the others need a breakthrough for mass production.     

Technology development and applications of composites at HAL

Composite materials for aerospace applications through in-house R & D and through collaboration with overseas aerospace organizations and National Laboratories covering a wide spectrum including glass/carbon/kevlar fibre reinforced plastics, metal and Nomex honeycomb sandwich structures, laminated composites, metal matrix composites and metallo-ceramic composites.     

Gas-phase compaction and unfolding of protein structures

Ion-mobility mass spectrometry is emerging as a powerful tool for studying the structures of less established protein assemblies. The method provides simultaneous measurement of the mass and size of intact protein assemblies, providing information not only on the subunit composition and network of interactions but also on the overall topology and shape of protein complexes. However, how the experimental parameters affect the measured collision cross-sections remains elusive. Here, we present an extensive systematic study on a range of proteins and protein complexes with differing sizes, structures, and oligomerization states. Our results indicate that the experimental parameters, T-wave height and velocity, influence the determined collision cross-section independently and in opposite directions. Increasing the T-wave height leads to compaction of the protein structures, while higher T-wave velocities lead to their expansion. These different effects are attributed to differences in energy transmission and dissipation rates. Moreover, by analyzing proteins in their native and denatured states, we could identify the lower and upper boundaries of the collision cross-section, which reflect the "maximally packed" and "ultimately unfolded" states. Together, our results provide grounds for selecting optimal experimental parameters that will enable preservation of the nativelike conformation, providing structural information on uncharacterized protein assemblies.     

Coumarin-conjugated multiwalled carbon nanotubes for potential biological applications: development and characterization

This work presents a novel cascade of chemical functionalization of multiwalled carbon nanotubes which allows the conjugation with differently substituted coumarins. Aim of the present work is to synthesize new materials able to rescue cells from the adverse effect of CNT particles since pristine CNTs are practically insoluble and tend to accumulate inside cells, organs and tissues. Moreover, it was reported that single walled CNTs particles show an adverse effect on keratinocytes through an oxidative mechanism, leading to NF-kB activation. The conjugation with coumarins, known superoxide anion scavengers, could switch the cytotoxicity of the new materials. The cascade functionalization of MWCNTs by sequential steps of carboxylation, acylation, amine modification and finally, coumarin conjugation have been performed and the synthesis and the chemical properties of several f-MWCNTs-coumarins have been exploited.     

Integrated scanning Kelvin probe-scanning electrochemical microscope system: development and first applications

The integration of a scanning Kelvin probe (SKP) and a scanning electrochemical microscope (SECM) into a single SKP-SECM setup, the concept of the proposed system, its technical realization, and first applications are presented and discussed in detail. A preloaded piezo actuator placed in a grounded stainless steel case was used as the driving mechanism for oscillation of a Pt disk electrode as conventionally used in SECM when the system was operated in the SKP mode. Thus, the same tip is recording the contact potential difference (CPD) during SKP scanning and is used as a working electrode for SECM imaging in the redox-competition mode (RC-SECM). The detection of the local CPD is established by amplification of the displacement current at an ultralow noise operational amplifier and its compensation by application of a variable backing potential (V(b)) in the external circuit. The control of the tip-to-sample distance is performed by applying an additional alternating voltage with a much lower frequency than the oscillation frequency of the Kelvin probe. The main advantage of the SKP-SECM system is that it allows constant distance measurements of the CPD in air under ambient conditions and in the redox-competition mode of the SECM in the electrolyte of choice over the same sample area without replacement of the sample or exchange of the working electrode. The performance of the system was evaluated using a test sample made by sputtering thin Pt and W films on an oxidized silicon wafer. The obtained values of the CPD correlate well with known data, and the electrochemical activity for oxygen reduction is as expected higher over Pt than W.     

溅射靶材的应用及发展趋势

由于集成电路、光碟及平面显示器等产业规模越来越大，这些高技术产业对各种超高纯金属及合金溅射靶材的需求量愈来愈多，本文对各种溅射靶的应用情况，市场及发展趋势作简要分析，供靶材生产厂参考。     

应用纳滤膜分离糖和盐的实验研究

选择NF-45纳滤膜进行糖和盐单组分和混合体系的分离实验研究,考察了纳滤膜分离性能随着操作压力、循环流量及料液浓度的变化所受到的影响。讨论了葡萄糖-氯化钠、蔗糖-氯化纳混合体系中糖和盐的相互影响作用,认为可以运用NF-45纳滤膜在适宜的操作条件（如操作压力、料液浓度）实现糖和盐的较好分离。     

Growth and development ofThiobacillus ferrooxidans for engineering applications

A bioprocessing approach for the extraction of base, nuclear and precious metals from refractory and lean grade ores has been reviewed in this paper. Characteristic morphological features ofThiobacillus ferrooxidans, the organism which has been extensively used for biooxidation of sulphide ores have been discussed. Mechanisms of chemoautotrophy and mineral oxidation have been illustrated. The current engineering applications of this microorganism have also been brought out. Various methods for accelerating the growth ofThiobacillus ferrooxidans for faster biooxidation and genetic manipulation for development of desired strains have been outlined.     

Gas-phase growth of diameter-controlled carbon nanotubes

We demonstrate gas-phase (aerosol) generation of diameter-controlled carbon nanotubes (CNTs) by employing size-controlled monodisperse nickel nanoparticles produced by the combination of pulsed laser ablation and electrostatic classification. The electrostatic classifier sorted agglomerated mono-area nickel particles, and then a subsequent heating process at ∼ 1200 °C created sintered single primary particles with very narrow size distribution. These isolated single primary particles were then sent to an aerosol reactor where free-flight CNTs were grown with acetylene and hydrogen mix at temperature of ∼ 750 °C. The resulting CNTs formed in this continuous gas-phase process were found to have a uniform diameter, which is commensurate with the diameter of the size-controlled catalytic nickel particles.     

Ferroelectric liquid crystals: development of materials and fast electrooptical elements for non-display applications

A brief overview is presented describing the development of ferroelectric liquid crystal materials revealing the electroclinic and DHF (deformed helix ferroelectric) properties and electrooptical elements utilizing these materials.     

Gas-phase production of gold-decorated silica nanoparticles

Gold-decorated silica nanoparticles were synthesized in a two-step process in which silica nanoparticles were produced by chemical vapor synthesis using tetraethylorthosilicate (TEOS) and subsequently decorated using two different gas-phase evaporative techniques. Both evaporative processes resulted in gold decoration of the silica particles. This study compares the mechanisms of particle decoration for a production method in which the gas and particles remain cool to a method in which the entire aerosol is heated. Results of transmission electron microscopy and visible spectroscopy studies indicate that both methods produce particles with similar morphologies and nearly identical absorption spectra, with peak absorption at 500-550 nm. A study of the thermal stability of the particles using heated-TEM indicates that the gold decoration on the particle surface remains stable at temperatures below 900?°C, above which the gold decoration begins to both evaporate and coalesce.     

Current trends in the development and applications of superconducting materials

The discovery of the phenomenon of superconductivity by Kamerlingh Onnes in 1911 was the first indication of the possibility of electrical conduction without any associated Joule loss. The technological application of the property (which was essentially manifested at liquid helium temperatures) had to await the development of stable superconducting materials capable of withstanding high currents and large magnetic fields. Although many materials — elements, alloys, ternary chalcogenides, and recently oxides — have been found to be superconducting, only a few of them have received attention for significant applications. This is based on three important parameters namelyT _c , the transition temperature,H _c2, the upper critical field andJ _c , the critical current density.T _c andH _c2 are considered intrinsic to the material, whileJ _c is influenced by the microstructure, and has to be optimised during fabrication of the material in the useful form. On these considerations, Nb-Ti, Nb₃Sn and V₃Ga have emerged as proven materials for significant applications while PbMo₆S₈ is still under development. Despite the fact that all these materials have to be used only at liquid helium temperatures on account of their lowT _c , major developments have taken place in harnessing particularly the niobium alloys to produce superconducting magnets. Towards the end of 1986, a break-through has been achieved in the direction of raising theT _c . Many ceramic oxides, notably Y₁Ba₂Cu₃O₇, have exhibitedT _c in the vicinity of 100 K. These materials have also been shown to have highH _c2, about 180 Tesla. Attempts are now being made to realise a highJ _c . It is too early to say whether such materials can be fabricated in suitable forms capable of carrying high currents. Among the major areas in which superconducting materials have so far been used, mention should be made of superconducting magnets for high energy particle accelerators, magnetohydrodynamic power generation, magnetic resonance imaging, and fusion research programmes. In other potential applications such as motors and magnetically levitated transportation, economic break-even has not been achieved, mostly on account of the need to use liquid helium. The discovery of the high temperature superconductors capable of operating at liquid nitrogen temperatures thus promises a revolution in electrical technology. The paper reviews the development and applications of superconducting materials, with reference to work being done in India. Talk delivered at the International Conference on Recent Advances in Materials and Processes, Varanasi, November–December 1987.