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Considering the ample evidence of involvement of the glutamate system in the pathophysiology of depression, pre-clinical and clinical studies have been conducted to assess the antidepressant efficacy of glutamate inhibition, and glutamate receptor modulators in particular. This review focuses on the use of glutamate receptor modulators in unipolar depression.
A method is developed to adjust a vorticity field to satisfy specified values for a finite number of Casimir invariants. The developed method is tested numerically for a neutral fluid in two dimensions. The adjusted vorticity field is adopted as an initial condition for simulated annealing (SA) of an incompressible, ideal neutral fluid and its magnetohydrodynamics (MHD), where SA enables us to obtain a stationary state of the fluid. Since the Casimir invariants are kept unchanged during the annealing process, the obtained stationary state has the required values of the Casimir invariants specified by our method.
We investigated the reason of the (imbalanced) accumulation of electrons in AIGaSb/lnAs/AIGaSb QW system in spite of the p-type conduction of undoped AIGaSb. It was found that the concentration of the accumulated electrons negligibly depended on the number of the interfaces, but increased linearly with the effective AlSb thickness. These results indicate that donor levels in AIGaSb are the dominant electron sources. We propose a model that the deep acceptors with larger concentration and donors coexist, and the electron accumulation depends on the energy position of the acceptor in AIGaSb with respect to the quantum level in the InAs well. Acceptor levels obtained experimentally are about 100 meV higher than the bottom of the InAs conduction band, and we succeeded in eliminating the electron accumulation by making the quantum level of the InAs well higher than this acceptor level. The origins of the donors and acceptors are also discussed.
The application of severe plastic deformation to metals provides a convenient procedure for achieving nanometer and submicrometer microstructures. Several different processing methods are available but Equal-Channel Angular Pressing (ECAP) is especially attractive because it provides an opportunity for preparing relatively large bulk samples. This paper describes the use of ECAP in preparing materials with ultrafine grain sizes and the subsequent properties of these materials at elevated temperatures. It is demonstrated that, provided precipitates are present to retain these small grain sizes at the high temperatures where diffusion is reasonably rapid, it is possible to achieve remarkably high superplastic elongations in the as-pressed materials and there is a potential for making use of this processing procedure to develop a superplastic forming capability at very rapid strain rates.
Lateral solid phase epitaxy (L-SPE) of amorphous Si (a-Si) films vacuum-evaporated on Si substrates with SiO2 patterns has been investigated, in which the film first grows vertically in the regions directly contacted to the Si substrates and then grows laterally onto SiO2 patterns. It has been found from transmission electron microscopy and Nomarski optical microscopy that use of dense a-Si films, which are formed by evaporation on heated substrates and subsequent amorphization by Si+ ion implantation, is essentially important for L-SPE. The maximum L-SPE length of 5–6μm was obtained along the <010> direction after 10hourannealing at 600°C. The kinetics of the L-SPE growth has also been investigated.
Control of epitaxial relationship of CaF2 films grown on Si(111) substrates was considered to be important to improve surface morphology and crystallini ty of GaAs films on CaF2/Si(111) structures. We successfully grew CaF2 films with the “type-A” epitaxial relationship on Si(111) substrates, that is, the crystallographic orientation of the CaF2 films were aligned in the same direction as that of the Si(111) substrates. These “type-A” CaF2 films were grown by a two step growth method. It was found that surface morphology of GaAs films on the CaF2/Si(111) structures was drastically improved by growth of the “type-A” CaF2 films.
In the optical reflectance spectrum of the random multilayers of a-Si:H/a-Si3N4+x:H, it is observed an anomalous peak which is explained by the classical localization of light propagation. The following two subjects are discussed in this report; (a). The Kramers-Kronig transformation is done including the anomalous disorder-related reflectance peak. Extra absorption coefficients Δα are obtained by this analysis. Energy dependence of the localization length 1(hv) of light propagation are obtained by 1(hv)=1/Δα(hv). (b). The other is the experiment on scaling where the ratio of the disorder and the average layer thickness is kept constant but the size of each layer is changed in each experiment
This paper reports in situ measurement of Young’s modulus and residual stress of electroless nickel films through the use of microfabricated nickel test structures, including electrostatic microactuators and passive devices. The test structures are fabricated in a new surface micromachining process, termed “nickel surface micromachining”, using electroless plated nickel as the structural layer and polysilicon as the sacrificial layer. Subsequent to fabrication, lateral resonant-type electrostatic microactuators of different geometries are resonated by electrical excitation. Using the measured resonant frequencies and knowledge of the device geometry, the Young’s modulus of the film is determined. The passive electroless nickel microstructures deform upon completion of the fabrication process due to residual stress in the film. Measurement of this deformation in conjunction with an appropriate mechanical model is used to determine the residual stress in the films.
To obtain informations about the correlation between structure and electrical property in metallic multilayers, we have fabricated Ni/Co superlattices with and without Pb as a surfactant by molecular beam epitaxy. From the observations of RHEED and x-ray diffraction patterns, we confirmed that the surfaces of Ni/Co superlattices with Pb are flatter and the interfaces are sharper than one without Pb, which means that Pb operates as an effective surfactant.We have investigated the electrical properties of superlattices by measuring magnetoresistance. The initial change of resistance with magnetic field from 0 to 1 kOe was larger for the superlattices with a surfactant, while once magnetic field was applied, the effect of a surfactant to resistivity change was not observed. This suggests that Pb also changes the initial magenetic domain structure and the magnetotransport property of Ni/Co superlattice is not sensitive to interface structure.
Effects of ion-irradiation on oxidation of silicon at low temperatures (130°C) in an argon and oxygen mixed plasma excited by electron cyclotron resonance (ECR) interaction are investigated. First, dependence of energy and flux of incident ions on the flow rate and the microwave power is evaluated. It is shown that the flow rate and the microwave power are key parameters for controlling the energy and the flux of incident ions, respectively. Second, growth kinetics of the oxide films are studied. The growth rate depends on the energy and the flux of argon ions irradiated to the substrate, and the growth thickness increases proportionally to the root square of the oxidation time. Thus, the growth rate is limited by diffusion of oxidants enhanced by irradiation with argon ions. The effect of substrate bias on oxidation characteristics is also discussed. The electrical properties of the oxide films are improved by increasing the bias. The improvement is due to the reduction of damage at the surface of the substrate induced by the irradiation.
We have successfully grafted polythiophene on polyethylene (PE) film with a three reactions step: gas phase bromination on PE, yielding PE-Br; substitution reaction of PE-Br with 2-thiophene thiolate anion, following by chemical oxidative polymerization. The polymerization was carried out in a suspension solution of anhydrous FeCl3 in CHCl3, yielding a reddish PE-PT film after dedoping with ethanol. ATR-FTIR shows that the polythiophene (PT) was grafted on PE in the 2,5-position; on the other hand, PT homopolymer shows a small amount of 2,4 coupling. XPS reveals higher intensity of the S2p, including neutral and positive sulfur. SEM image reveals the island of PT on the PE film. AFM analysis found the thickness of the island is in the range of 120–145 nm. The conductivity of these thin films is in the range of 10−6 S/cm.
A new method of making conductive composite films by permeation of the conducting guest species into the host is reported. A layer of poly(3-n-dodecyl thiophene) (P3ddt) is embedded at the surface of polyimide by permeation of the monomer or polymer (in solution in tetrahydrofuran or chloroform) into a solution of polyamic acid in n-methyl pyrrolidinone or dimethyl acetamide. The resulting composites were imidised and polymerized (if necessary). Chemical imidisation yielded composite -films that retained the conducting polymer even when the composite was subjected to solvent extraction. The films were conductive upon doping with iodine and recovered conductivity when they were exposed to iodine vapor subsequent to thermal de-doping. Thermogravimetry showed that the amount of thiophene incorporated into the polyimide was higher for permeation of the polymer than that of the monomer; however, the amount of p3ddt incorporated by the latter method was still higher than the amount that could be incorporated by blending polyamic acid with p3ddt. The levels of conductivity and speed of recovery for doped films were also higher for the permeated films. Results of scanning electron microscopy suggested that the higher mobility afforded by contact in the liquid state have contributed greater entanglement between the constituents leading to higher thermal and solvent resistance of the conducting constituent. The permeation method could be adopted to form composite films in solvent systems that are not completely miscible.
Using the technique of equal-channel angular (ECA) pressing, it is possible to reduce the grain size of polycrystalline materials to the submicrometer level. Thus, this processing technique has the potential for producing materials which may exhibit superplasticity. This paper describes various factors affecting the development and evolution of the microstructure produced by ECA pressing. Optimization of such factors is then presented for the advent of superplasticity.
The shape of several waveguide end of samples for photoluminescence absorption spectroscopy (PLAS) was studied by atomic force microscope (AFM), because there was an experimental problem where some samples for PLAS did not work. Using the result of AFM, the waveguide end was reshaped by plasma dry etching. The shortening of the etching time was an effective method to improve the structure of the waveguide end. Secondly, the PLAS method was extended to the other materials from a-Si:H. The PLAS signal of amorphous carbon nitride a-CNx was detected for the first time. Amorphous carbon nitride a-CNx film itself and the interface between a-CNx and a-Si02 are found as good as a-Si:H and the interface between a-Si:H and a-Si 3N4+x:H, respectively.
We have confirmed that grain boundaries are related to leakage problems in Ta2O5/SiON capacitors for high dielectric DRAMs. XRD studies using an intensity ratio of (200) to (001) showed that the crystallographic structure of Ta2O5 film was strongly dependent on preparation conditions. As the (200) oriented grains grew faster than the other grains, it became important to control its grain growth in forming uniform grain boundaries. TEM observation has shown that Ta2O5 film with a high intensity ratio of (200) to (001) was made up of large size grains and had SION interface intruding into grain boundaries. By using the current-mode AFM, we could monitor leakage current directly through grain boundaries on Ta2O5 film.
A hyperbranched conjugated polymer containing triphenylamine was prepared by the Grignard reaction of tris(4-bromophenyl)amine 1, via the coupling of N, N-bis(4-bromophenyl)-N-(4-bromomagnesiophenyl)amine 2 with the catalytic amount of Ni(acac)2. Grignard reagent 2 reacted as an AB2-type monomer to give hyperbranched conjugated polymer 3 in a one-step process. Polymer 3 was also obtained via the Pd-catalyzed coupling of N, N-bis(4-bromophenyl)-4-animobenzeneboronic acid 4. Polymer 3 had an average molecular weight of 4.0–6.3×103 and was found to be soluble in organic solvents such as THF and CHC13. A cast film had an anodic peak at 0.95–1.20 V vs. Ag wire. It was dark blue above the oxidation potential and brown-yellow in the neutral state. When polymer 3 was doped with iodine, its conductivity rose to 0.8–3.0 S/cm