氮化硅反应烧结设备PLC自动控制

本文通过对氮化硅反应烧结设备的可编程控制，说明可编程控制技术是材料学科的一个重要应用方向。     

Colonoscopy: the initial test for acute lower gastrointestinal bleeding

Chronic intracerebral hematoma is a fairly rare clinical entity. We report a case of a 76-year-old man who presented with left hemiparesis on admission. CT scan revealed a hematoma in the right basal ganglia. Under observation, the hyperdense lesion on CT scan changed to isodense 2 weeks after admission and then changed to low density 4 weeks after the first scan. These findings suggested hypertensive intracerebral hemorrhage but, 3 months after admission, hemiparesis grew worse and the appearance of the lesion changed from low density to isodensity again. When the patient presented disturbance of consciousness, CT scan revealed a new hemorrhage from the capsule of the hematoma and the new hematoma markedly expanded 2 weeks later. The contents of the hematoma was old uncoagulated hematoma resembling chronic subdural hematoma and drainage was carried out under local anesthesia. The patient died because of respiratory failure and autopsy was performed. Histopathologically cancer cells were shown in the hematoma cavity and the capsule of the hematoma was composed of two layers: a collagenous layer on the inside and a granulation layer with neovascular system on the outside. As the neovascular system existed on the outside of the capsule, the rebleeding occurred outside the capsule and the second hematoma appeared beside the initial one. We suspected that the initial bleeding occurred in the tumor tissue and the rebleeding occurred in the granulation layer of the capsule.     

Low gate interface traps AlGaN/GaN HEMTs using a lattice matched ZrZnO transparent gate design

AlGaN/GaN metal–insulator–semiconductor high electron mobility transistors (MIS-HEMTs) using a radio-frequency magnetron sputtered ZrZnO transparent oxide layer as a gate insulator are investigated and compared with traditional GaN HEMTs. A negligible hysteresis voltage shift in the C–V curves is seen, from 0.09 V to 0.36 V, as the thickness of ZrZnO films increases. The composition of ZrZnO at different annealing temperatures is observed using X-ray photoelectron spectroscopy (XPS). The ZrZnO thin film achieves good thermal stability after 600 °C, 700 °C and 800 °C post-deposition annealing (PDA) because of its high binding energy. Based on the interface trap density analysis, D_it has a value of 2.663 × 10¹² cm⁻²/eV for 10-nm-thick ZrZnO-gate HEMTs and demonstrates better interlayer characteristics, which results in a better slopes for the I_ds degradation (5.75 × 10⁻¹ mA/mm K⁻¹) for operation from 77 K to 300 K. The 10-nm-thick ZrZnO-gate device also exhibits a flat and a stable 1/f noise, as V_GS–V_th, and at various operating temperatures. Therefore, ZrZnO has good potential for use as the transparent film for a gate insulator that improves the GaN-based FET threshold voltage and improves the number of surface defects at various operating temperatures.     

Decision-making in a single-period inventory environment with fuzzy demand

This paper first defines the profitability to be the probability of achieving a target profit under the optimal ordering policy, and introduces a new index (achievable capacity index; I_A) which can briefly analyze the profitability for newsboy-type product with normally distributed demand. Note that since the level of profitability depends on the demand mean μ and the demand standard deviation σ if the related costs, selling price, and target profit are given, the index I_A is a function of μ and σ. Then, we assess level performance which examines if the profitability meets designated requirement. The results can determine whether the product is still desirable to order/manufacture. However, μ and σ are always unknown, and the demand quantity is common to be imprecise, especially for new product. To tackle these problems, a constructive approach combining the vector of fuzzy numbers is introduced to establish the membership function of the fuzzy estimator of I_A. Furthermore, a three-decision testing rule and step-by-step procedure are developed to assess level performance based on fuzzy critical values and fuzzy p-values.     

Production of an extremly low dose procaterol HCl preparation by fluidized-bed coating method: in vitro and in vivo evaluation

A convenient and reliable method to prepare procaterol HCl oral dosage form at an extremely low dosage (25 microg/cap) is presented in this paper. Procaterol HCl was mixed with the film-forming agent hydroxypropyl methylcellulose in an aqueous solution, which was then spray-coated on sugar spheres (Nu-pareil PG 20/25) to produce procaterol HCl pellets. The IR spectra of coated and noncoated pellets indicated that procaterol HCl was coated on the sugar spheres successfully with a weight increment less than 1%. Most of the coated pellets were able to pass through an 18-mesh screen with no agglomeration. The average weights of coated pellets filled inside of capsules were monitored during the filling process. A simple liquid chromatographic method was developed and validated for the assay and uniformity test of procaterol HCl in different dosage forms. The results of assay and content uniformity test for both in-house product and a commercial product, i.e., Meptin-mini tablet, were satisfied. The data of f(2) function and ANOVA analysis for the dissolution profiles of both procaterol HCl products suggested that they are pharmaceutical equivalent.In an in vivo study (n = 24), a single dose of 75 microg procaterol HCl was administrated to each volunteer and the plasma concentration of procaterol was determined by a LC/MS/MS method, developed by the same authors. There were no significant differences (p > 0.05) in the data of AUC(0-->16 h), AUC(0-->infinity), C(max), and MRT for both preparations. It is confirmed that the pellets capsule produced in this study is bioequivalent with Meptin-mini tablet.     

Global exponential stability for uncertain bidirectional associative memory neural networks with multiple time‐varying delays via LMI approach

The global exponential stability for uncertain delayed bidirectional associative memory neural networks (DBAMNN) with multiple time‐varying delays is considered in this paper. Delay‐dependent criteria are proposed to guarantee the robust stability of DBAMNN via linear matrix inequality approach. Two classes of system uncertainties are investigated in this paper. Some numerical examples are given to illustrate the effectiveness of our results. From the numerical simulations, significant improvement over the recent results can be observed. Copyright © 2007 John Wiley & Sons, Ltd.     

A New Aspect of Magnesium Bromide‐Promoted Enantioselective Aryl Additions of Triaryl(tetrahydrofuran)aluminum to Ketones Catalyzed by a Titanium(IV) Catalyst of trans‐1,2‐Bis(hydroxycamphorsulfonylamino)cyclohexane

A novel aspect of MgBr₂‐promoted asymmetric triarylaluminum‐tetrahydrofuran [AlAr₃(THF)] additions to ketones catalyzed by a titanium catalyst of 20 mol% trans‐1,2‐bis(hydroxycamphorsulfonylamino)cyclohexane ( 2 ) is reported. The catalytic system works excellently for aromatic ketones with either an electron‐withdrawing or an electron‐donating substituent on the aromatic ring at the 2′‐, 3′‐, or 4′‐positions, affording tertiary alcohols in excellent enantioselectivities of ≥90% ee, except for the cases of phenyl addition to 2′‐methoxyacetophenone and 4‐trimethylsilylphenyl (4‐TMSC₆H₄) addition to acetopheneone.     

A novel wavelength-division multiplexer using grating-assisted two-mode interference

A novel design of wavelength-division multiplexer based on two-mode interference assisted by a highly dispersive grating structure is two-dimensionally simulated and analyzed using finite-difference time-domain method. We show that the designed grating waveguide provides a mode-dependent reflection spectrum which can be used to modify the beat lengths of the two selected wavelengths 1342 and 1560 nm, so that they can be divided in a very short distance about 48 /spl mu/m. Simulation results show that contrasts /spl sim/12 dB and insertion losses about 2 dB could be achieved.     

Influence des agrégats sur le rendement d'un réacteur à transport pneumatique

The evaluation of the performance of a pneumatic transport reactor operating at low gas velocity and high solid volumic concentration is presented. This reactor has a high length-diameter ratio and can be considered as a representative tube of a multitubular reactor with gas—solid suspension circulating inside the tubes. Two experimental techniques have been used: ozone adsorption or catalytic ozone decomposition on a porous solid. The agregation of the particles, which has an important effect on the hydrodynamics, does not contribute to the diffusional resistance. The design of an industrial reactor should be accordingly relatively simple.