Preparation of Plate‐Like Sodium Niobate Particles by Hydrothermal Method

Sodium niobate NaNbO₃ hydrate (NN‐hydrate) particles with a plate‐like morphology were prepared at 140°C for 2 h in 12 mol/L of NaOH by the hydrothermal method. Bar‐like Na₈Nb₆O₁₉·13H₂O particles were synthesized at as low as 100°C for 2 h. This work demonstrates that by carefully optimizing the reaction condition, we can selectively fabricate niobate structures, including the bar‐like, plate‐like, fibers and cube particles through a direct reaction between NaOH solution and Nb₂O₅. It was found that Nb₆O₁₉^8? formed was an important premise for formation of the NN‐hydrate, and lower [OH^–] was not favorable in preparing the NN‐hydrate as there was an optimum [OH^?]. Through researching effects of the reaction temperature, time, concentration of NaOH, and content of Nb₂O₅ on the NN‐hydrate structure and evolution, the formation mechanism from solid reactants to the intermediate were investigated. After calcining at 800°C, the synthesized NN‐hydrate particles made a phase almost transform to the perovskite NaNbO₃, and the morphology of these calcined particles was still plate‐like.     

Preparation of Morphology‐Controlled Plate‐Like Sodium Niobate Particles by Hydrothermal Synthesis

Sodium niobate (NaNbO₃) particles with plate‐like morphology and hexagonal unit cells were prepared by the hydrothermal method. The result of SEM showed that the hexagonal NaNbO₃ were characterized by plate‐like morphology with a diameter of 5–15 μm and a thickness of 1–2 μm. The crucial influences on the morphology and crystal phase of the NaNbO₃, such as concentration of [OH^?], surfactant, and K⁺:Na⁺ ratio, were established. By further calcination treatment, the plate‐like hexagonal NaNbO₃ particles could be completely transformed into perovskite structure without morphology change. The XRD and EBSD results indicate that the major face of the calcined particles is parallel to the crystallographic (001)_pc (pseudo cubic index) plane. Compared with the traditional high‐temperature molten salt method, this work provides a simpler way to prepare the template for fabricating textured ceramics.     

Probabilistic performance assessment of wind energy conversionsystems

This paper describes the development of a general probabilistic model of an autonomous wind energy conversion system (WECS) composed of several wind turbines (wind farm) connected to a load and a battery storage. The proposed technique allows the simulation of wind farms containing identical or different wind turbines types and considers a bidirectional flow of power in and out of the battery. The model is based upon a simple procedure to estimate the joint probability distribution function of the total available wind power and that of the turbines operating modes due to hardware failure. A methodology is also developed to use the proposed model to determine an upper limit on the size of the battery storage required for a given number of turbines to satisfy the load with a certain expected energy not supplied (EENS). The model can also be used to evaluate the energy purchased from or injected to the grid in the case of grid-connected systems     

Low Temperature Magnetization of Two Dimensional 3He on Three Layers of HD Preplated Graphite

We have measured the low temperature magnetization of submonolayer ³He on three layers of HD preplated graphite. NMR measurement has been performed by progressively adding ⁴He to the system, to prevent ³He atoms from being trapped in substrate heterogeneities and to change the areal density of ³He. The exchange constant (J) is found to have a similar density dependence to that for two layers of HD preplated one. The magnetization in the antiferromagnetic region increases gradually down to 100 K and shows no evidence corresponding to a spin gap.     

Human immunodeficiency virus type 2 envelope glycoprotein binds to CD8 as well as to CD4 molecules on human T cells

We report here that human immunodeficiency virus type 2 (HIV-2) envelope glycoprotein (gp105), but not HIV-1 gp120, can bind to CD8 molecules as well as to CD4 molecules on human T cells. This phenomenon may lead to differences in the life cycles of HIV-1 and HIV-2, and it may be related to the differences in disease manifestations of HIV-1 and HIV-2 infection, including longer survival of HIV-2-infected patients.     

Influence of Spin Fluctuations Upon Heat Capacity of 2D Fermi Liquid Formed on Hectorite

We measured low-temperature heat capacities of two-dimensional Fermi liquid (2D FL) formed on Hectorite down to 15mK. At a coverage where mean atomic distance is comparable to that of bulk ³ He liquid, we found that the temperature dependence deviates considerably from the expected linearity. To account for the deviation we carried through integrals including RPA spin susceptibility for the Stoner-Hubbard(SH) or the Landau's Fermi liquid (LFL) models over the effectively entire, energy-momentum space without imposing the paramagnon approximation or the like. We found numerically that the spin fluctuation develops a T ² correction at T<T* which, at T>T*, is taken over by a Tlog T term where T* is some hundredths of T _F . With these corrections we are able to interprete the data and have determined the parameters for each model consistently at the densities observed.     

Inhibitory effect of forskolin on myosin phosphorylation-dependent and independent contractions in bovine tracheal smooth muscle

In bovine tracheal smooth muscle, carbachol (CCh, 1 microM) and high K+ (72.7 mM) induced sustained increases in cytosolic Ca2+ level ([Ca2+]i), myosin light chain (MLC) phosphorylation and force of contraction. Forskolin (FK, 1-10 microM) inhibited the CCh-induced increase in [Ca2+]i, MLC phosphorylation and force in parallel. In contrast, FK inhibited the high K(+)-induced contraction and MLC phosphorylation without changing [Ca2+]i. In the absence of extracellular Ca2+ (with 0.5 mM EGTA), CCh (10 microM) and caffeine (20 mM) induced transient increase in [Ca2+]i and contractile force by releasing Ca2+ from cellular store. FK strongly inhibited the CCh-induced Ca2+ transient, but failed to inhibit the caffeine-induced Ca2+ transient. In the absence of external Ca2+, 12-deoxyphorbol 13-isobutylate (DPB, 1 microM) induced sustained contraction without increase in [Ca2+]i and MLC phosphorylation. FK inhibited this contraction without changing [Ca2+]i. In permeabilized muscle, Ca2+ induced contraction in a concentration-dependent manner. FK (10 microM) and cAMP (1-100 microM) shifted the Ca(2+)-force curve to the higher Ca2+ levels. CCh with GTP, GTP gamma S or DPB enhanced contraction in the presence of constant level of Ca2+. Forskolin and cAMP also inhibited the enhanced contractions in the permeabilized muscle. In the permeabilized, thiophosphorylated muscle, ATP induced contraction in the absence of Ca2+. cAMP (300 microM) had no effect on this contraction. These results suggest that forskolin inhibits agonist-induced contraction in tracheal smooth muscle by multiple mechanisms of action; 1) inhibition of MLC phosphorylation by reducing Ca2+ influx and Ca2+ release, 2) inhibition of MLC phosphorylation by changing the MLC kinase/phosphatase balance, and 3) inhibition of regulatory mechanism which is not dependent on MLC phosphorylation.     

An Assessment of µ-Czochralski, Single-Grain Silicon Thin-Film Transistor Technology for Large-Area, Sensor and 3-D Electronic Integration

Single-grain (SG) thin-film transistors (TFTs) fabricated inside location-controlled silicon grains using the mu-Czochralski method are benchmarked for analog and RF applications. Each silicon grain is defined by excimer laser recrystallization of polysilicon. Thin-film transistors may be fabricated in this manner on silicon or low-cost flexible plastic substrates as processing temperatures remain below 350degC, making the SG-TFT a potential enabling technology for large-area highly integrated electronic systems or systems-in-package with low manufacturing cost. Operational amplifier and voltage reference circuits of varying complexity were designed and measured in order to evaluate the effects of channel position and processing variation on analog circuits. A two-stage telescopic cascode operational amplifier fabricated in an experimental 1.5 mum SG-TFT technology demonstrates a DC gain of 55 dB (unity-gain bandwidth of 6.3 MHz), while a prototype CMOS voltage reference with a power supply rejection ratio (PSRR) of 50 dB is also demonstrated. With f_T comparable to single-crystal MOSFETs of comparable gate length, the SG-TFT can also enable RF circuits for wireless applications. A 12 dB gain RF cascode amplifier with on-chip inductors and operating in the 433 MHz ISM band is demonstrated. Excellent agreement with simulations is attained using a modified BSIM-SOI model extracted from measurements of experimental SG-TFT devices.     

Single-grain Si thin-film transistors SPICE model,analog and RF circuit applications

Single-grain thin-film transistors (SG-TFTs) fabricated inside location-controlled using μ-Czochralski process exhibit SOI-FETs like performance despite processing temperatures remaining below 350 °C. Thus, the SG-TFT is a potential technology for large-area highly-integrated electronic system and system-in-package, taking advantage of the system-on-flexible substrate and low manufacturing cost capabalities. The SG-TFT is modeled based on the BSIMSOI SPICE model where the mobility parameter is modified to fit the SG-TFT behavior. Therefore, analog and RF circuits can be designed and benchmarked. A two-stage telescopic cascode operational amplifier fabricated in a prototype 1.5 μm SG-TFT technology demonstrates DC gain of 55 dB and unity-gain bandwidth of 6.3 MHz. A prototype CMOS voltage reference demonstrates a power supply rejection ratio (PSRR) of 50 dB. With unity-gain frequency, f_T, in the GHz range, the SG-TFT can also enable RF circuits for wireless applications. A 12 dB gain RF cascode amplifier with integrated on-chip inductors operating in the 433 MHz ISM band is demonstrated.