Oxidation of formic acid at a high surface area supported platinum modified by foreign metal adatoms

The anodic oxidation of formic acid was studied on platinum distributed in the form of small particles in a porous substrate modified by metal adatoms deposited at underpotentials. The rate of the reaction was greatly enhanced on the commercial catalyst Powercat 3000 (PC 3000). The hydrogen adsorption and the underpotential deposition of several metals at PC 3000 were shown to be dissimilar to that at smooth polycrystalline Pt. Steady-state and long-term experiments were performed to determine the stability of this electrode.     

Neuropsychological function in adults with attention-deficit hyperactivity disorder

Pacemaker therapy in patients with atrial fibrillation means the best current pacemaker therapy for patients with bradycardias with the aim to avoid the onset of atrial fibrillation and to establish DDD pacing despite of a history of atrial tachyarrhythmias. The newer application of pacing is the suppression of atrial arrhythmias in patients with medical refractory atrial tachyarrhythmias. Patients with slow ventricular rates and permanent atrial fibrillation should receive a VVI-pacemaker, if the bradycardias causes syncope, dizziness or a decrease of their exercise tolerance. In case of chronotropic incompetence the pacemaker should provide rate responsive pacing. Patients with sick sinus syndrome should receive an atrial (AAI) or dual-chamber (DDD) pacemaker, because patients with these in contrast to VVI-pacemakers develop less often atrial fibrillation and subsequent complications such as atrial thromboembolism. A dual-chamber or VDD-pacemaker--the latter connected to a VDD-single-lead--is indicated in patients with advanced AV-block. Atrial fibrillation occurs in 3 to 6% of the patients with no history of arrythmia and is, if pacemakers have no automatic mode switch, an often reason to program the devices to the VVI-pacing mode. Nowadays, most DDD(R)-pacemakers provide an automatic mode switch: During an atrial tachycardia the pacemaker switches to a VVI/VVIR mode and restores the initial DDD(R)-pacing mode with termination of the arrhythmia. In respect to the newer applications, one approach to prevent atrial tachyarrhythmias is permanent atrial pacing. As lower pacing rates of 80 to 90 ppm are usually needed and many patients hardly tolerate these pacing rates, new algorithms are under clinical investigation. Another approach is the simultaneous depolarization of the right and left atrium. Biatrial pacing is performed with one lead in the high right atrium and another lead in the coronary sinus. Another solution is bifocal atrial pacing with leads placed in the high right atrium and in the coronary sinus ostium. One effect of the new pacing techniques is to shorten interatrial conduction times. Therefore, biatrial pacing has become a therapy to prevent atrial arrhythmias deriving from delayed interatrial conduction times. As atrial reentry circuits seem to be important in atrial fibrillation, multisite atrial pacing is also performed in patients with medical refractory paroxysmal atrial fibrillation. Preliminary results suggest a more effective prevention of atrial fibrillation; nevertheless, these techniques should be still restricted to patients enrolled in clinical studies.     

本体思想在高速切削专家系统中的应用

为共享和重用高速切削领域内已有知识,把本体思想引入到该领域的知识表示中,提出了基于概念、关系、属性、规则和实例五要素的高速切削领域本体的形式化定义,建立了高速切削领域本体库.采用巴科斯范式对领域本体进行统一的描述和表达,并利用关系数据库的形式存储.以本体库作为专家系统的知识库,采用实例相似度及切削参数智能优化相结合的检索推理机制,构建了高速切削专家系统.系统为高速切削知识的检索、重用与共享提供了一个有效的平台,从而实现对高速切削领域内已有知识最大限度的利用.     

Cotton Yarn Sizing by Acrylamide Grafted Starch Copolymer

Synthesis and characterization of copolymer obtained by grafting acrylamide onto hydrolyzed potato starch and its application in cotton yarn sizing were presented in this work. Some process parameters of starch hydrolysis and grafting, like as hydrolysis yield, grafting yield, grafting percentage, graft efficiency, and monomer to polymer conversion were determinated. Molar mass values of hydrolyzed starch and copolymer samples are located in a narrow range of 1 × 10⁵ to 1 × 10⁷ and 1 × 10² to 1 × 10⁴. Grafted hydrolyzed starch, as a sizing agent, gives better results than nongrafted, particularly in terms of sizing uniformity, yarn mechanical parameters, and easier removal in subsequent desizing process.     

Metabolic mapping of the effects of oral alcohol self-administration in rats

A method for the quantitation of protein carbonyls, which have been widely employed as markers of protein oxidative damage, is described. Protein carbonyls were derivatized with tritiated sodium borohydride and the tritiated proteins were separated on SDS-PAGE. Protein bands, visualized by Coomassie blue staining, were then excised and incubated in 30% H2O2 at 60 degrees C for 48 h. Tritium, incorporated into the proteins, was quantitated by liquid scintillation counting after gel solubilization by H2O2. This method can be applied to the measurement of carbonylation of specific proteins as it employs SDS-PAGE and has the advantage that unreacted NaB3H4 in the labeling reaction mixture need not be removed. The present method, when combined with immunochemical detection of protein carbonyls, should be very useful in the quantitation of oxidative damage to individual proteins.     

Supplemental methionine and time of supplementation effects on ruminal fermentation, digesta kinetics, and in situ dry matter and neutral detergent fiber disappearance in cattle

Two experiments were conducted to study the effects of methionine supplementation on ruminal fermentation and digesta kinetics. In Exp. 1, nine ruminally cannulated beef heifers (average initial BW = 527 kg) in a crossover design were fed low-quality grass hay and cottonseed meal with or without 11.4 g of supplemental methionine (polysaccharide-coated). Particulate and fluid kinetics, rate of DM and NDF disappearance, ruminal VFA and NH3 N concentrations, and pH were not altered (P > .10) by supplemental methionine; however, ruminal purine concentration was greater (P < .05) in methionine-supplemented heifers than in unsupplemented heifers. In Exp. 2, 12 ruminally cannulated Holstein steers (average initial BW = 622 kg) grazing a fescue pasture were allotted to one of three groups: no supplemental methionine (CON) or 11.4 g of supplemental methionine fed at 0700 (AM) or at 1200 (PM). Forage intake, particulate kinetics, ruminal fluid kinetics, pH, VFA, and NH3 N concentrations were not altered (P > .10) by supplemental methionine or supplementation time. In situ rate of DM and NDF disappearance was greater (P < .05) in supplemented steers than in CON steers; AM steers exhibited faster (P < .05) rates than PM steers. Overall, methionine supplementation of low-quality forage increased ruminal purine concentration but did not alter in situ fermentation or digesta passage, whereas supplementation at 0700, but not at 1200, of steers grazing fescue forage increased rate of NDF fermentation.     

Synthesis and formation mechanism of submicrometre spherical cordierite powders by ultrasonic spray pyrolysis

Cordierite powders containing very pure submicrometre spherical particles have been synthesized by the ultrasonic spray pyrolysis. Aqueous solutions of silicic acid, Al(NO3)3·9H2O and MgCl2·6H2O were used as precursors. Scanning electron micrographs have shown that particle surfaces were smooth and the mean particle diameter was 0.834 m. For the estimation of chemical and phase composition and phase transformation temperatures, differential thermal analysis, thermogravimetric analysis, X-ray diffraction, energy dispersive spectroscopy and infrared analysis have been applied. It was found that during spray pyrolysis, the condensation of silicic acid mostly occurred while aluminium and magnesium ion remained incorported between Si–O–Si chains. By subsequent heating to over 800°C, Si–O–M bonds (M=Al, Mg) were formed. The synthesis of cordierite occurred by the crystallization of -cordierite from the amorphous phase at 900°C followed by the phase transformation of - into -cordierite in the temperature range 1100–1200°C.     

发挥咨询业作用,推进工程项目管理

承包商对工程的具体掌控力要远高于业主方,业主方面对工程实施中的各种问题往往鞭长莫及。为了帮助业主方从源头上实现项目的成功管理,就要发挥工程咨询机构的作用。本文论述了工程咨询机构在招标阶段项目管理的核心内容,指明了其在招标阶段的关键工作,在一定程度上实现了项目资源的优化配置,为业主节约了成本和效益最大化。同时,也分析了我国目前项目管理发展中存在的问题,并参照国内外先进管理思想和管理模式提出了我国工程咨询机构的发展方向及相应对策,对我国工程咨询业的发展有一定的参考价值。     

Modifications to electrolytic respirometer systems for precise determination of BOD exertion kinetics in receiving waters

Modifications to an electrolytic respirometric system are described which facilitate precise measurements of BOD progressions for low substrate concentration (BOD₅ < 20 g m^?3) as found in natural waters receiving organic enrichment. Samples may be incubated at any desired temperature or dissolved oxygen concentration with automatic hourly monitoring of the BOD progression. Subsamples may be withdrawn at any time without interference to the measurement. The system is independent of atmospheric temperature and pressure fluctuations and has a detection sensitivity of 0.05 mg of oxygen. Nomographs are presented to enable the maximum dissolved oxygen deficit, and the “apparent lag” time to be estimated. CO₂ removal, which may result in an extended lag phase, need not be used for BOD values below 50 g m^?3 provided adequate buffering is supplied.     

Structurally related peptide agonist, partial agonist, and antagonist occupy a similar binding pocket within the cholecystokinin receptor. Rapid analysis using fluorescent photoaffinity labeling probes and capillary electrophoresis

The molecular basis of ligand binding to receptors provides important insights for drug development. Here, we explore domains of the cholecystokinin (CCK) receptor that are critical for ligand binding, using a novel series of fluorescent photolabile probes, receptor proteolysis, and rapid high resolution separation of peptide fragments by capillary electrophoresis. Each probe incorporated the same fluorophore and a photolabile p-benzoylphenylalanine at the amino terminus of the pharmacophoric domain (residue 24 of CCK-33) of CCK analogues representing full agonist, partial agonist, and antagonist of this receptor. Each was used to label the CCK receptor expressed on Chinese hamster ovary-CCKR cells, with the labeled domain then released by cyanogen bromide cleavage. Capillary electrophoresis with laser-induced fluorescence detection achieved an on-capillary mass sensitivity of 1.6 attomoles (10(-18) mol), with an excellent signal-to-noise ratio. Each of the biologically divergent, but structurally similar probes saturably and specifically labeled the same receptor domain, consistent with conservation of "docking" determinants. This had an apparent mass of 2.9 kDa, most consistent with the first extracellular loop domain. An additional probe having its site of covalent attachment in a different region of the probe (residue 29 of CCK-33) labeled a distinct receptor fragment with differential migration on capillary electrophoresis (third extracellular loop). Identification of the specific receptor residue(s) covalently linked to the amino-terminal probes must await further fragmentation and sequence analysis.