大型衡器现场检定的标准砝码替代法——衡器检定中非常规的方法之一

衡器检定通常是采用直接加砝码法。但在一些实际检定中,有时需要采取某些非常规的方法,标准砝码的替代法就是方法之一。标准砝码的替代法即解决了检定现场砝码不足的问题。又满足了进行量传的要求。     

A Novel Process to Synthesize High-Quality Ferrovanadium Nitride

Metallurgical and Materials Transactions B - In the present work, high-quality ferrovanadium nitride, which has a relative high nitrogen content and a low carbon content, has been prepared by...     

腔体式吸收器与真空管吸收器的热性能比较

本文分析了槽形抛物镜聚光集热器中管族结构和环套结构的腔体式吸收器以及真空吸收器的热物理特征,画出其热阻网络,建立太阳能一般性控制方程,并以此为依据对这三种吸收器的热性能进行了数值分析比较。     

Classification and mass production technique for three-quarter shoe insoles using non-weight-bearing plantar shapes

We have developed a technique for the mass production and classification of three-quarter shoe insoles via a 3D anthropometric measurement of full-size non-weight-bearing plantar shapes. The plantar shapes of fifty 40-60-year-old adults from Taiwan were categorized and, in conjunction with commercially available flat or leisure shoe models, three-quarter shoe-insole models were generated using a CAD system. Applying a rapid prototype system, these models were then used to provide the parameters for manufacturing the shoe insoles. The insoles developed in this study have been classified into S, M and L types that offer user-friendly options for foot-care providers. We concluded that these insoles can mate tightly with the foot arch and disperse the pressure in the heel and forefoot over the foot arch. Thus, practically, the pressure difference over the plantar region can be minimised, and the user can experience comfort when wearing flat or leisure shoes.     

Induction of cytochrome P450 1A in hamster liver and lung by 6-nitrochrysene

The present study has determined the effect of 6-nitrochrysene (6-NC) on hepatic and pulmonary cytochrome P450 (P450)-dependent monooxygenases using hamsters pretreated with the nitrated polycyclic aromatic hydrocarbon (nitro-PAH) at 5 mg/kg per day for 3 days. Pretreatment with 6-NC elevated serum gamma-glutamyltranspeptidase, lactate dehydrogenase, and bilirubin levels. Liver S9 fractions prepared from controls and hamsters pretreated with 6-NC markedly increased mutagenicity of the nitro-PAH in Salmonella typhimurium tester strains TA98, TA100, and TA102. The pretreatment selectively increased 1-nitropyrene reductase activities of lung cytosol and liver and lung microsomes. Pretreatment with 6-NC resulted in increases of microsomal 7-ethoxyresorufin and methoxyresorufin O-dealkylases activities in liver and lung without affecting the monooxygenase activities in kidney. Immunoblot analysis of microsomal proteins using mouse monoclonal antibody 1-12-3 to rat P450 1A1 revealed that 6-NC induced P450 1A-immunorelated proteins in liver and lung. RNA blot analysis using mouse P450 1A1 cDNA showed that 6-NC increased liver and lung P450 1A mRNA. 6-NC had no effect on the kidney P450 protein and mRNA. The present study demonstrates that the hamster enzymes can support 6-NC metabolic activation and the nitro-PAH induces liver and lung P4501A via a pretranslational mechanism.     

Prediction of mandibular autorotation

PURPOSE: The purpose of this investigation was to test the hypothesis that the mandible rotates around the same point during maxillary impaction surgery as during initial jaw opening. This point, called the center of mandibular autorotation (CAR), could then be used to predict mandibular position and to decide whether only maxillary impaction would be needed to correct the occlusion and the facial profile. PATIENTS AND METHODS: Preoperatively, two lateral cephalograms were obtained from a consecutive series of 20 patients who underwent maxillary impaction without concomitant mandibular ramus osteotomy. One cephalogram was taken with the mandible in centric relation using a wax bite wafer and another with a jaw opening of 10 mm using a fabricated acrylic bite block with the mandible manipulated to its most retruded position. The CAR was calculated before and after jaw opening using the Rouleaux method on the lower incisor and gonion point. A third lateral cephalogram was taken within 2 days postoperatively. The postoperative lower incisal point was then transferred to the first cephalogram using cranial base superimposition. RESULTS: When the preoperative and postoperative distances between CAR and incisal point were compared, there was no significant difference between these distances, proving the hypothesis. CONCLUSIONS: The method used is a practical and precise way to determine the center of mandibular autorotation on an individual basis. The center of rotation during initial jaw opening is the same as during impaction surgery.     

Application of factor method for minimum reflux: Multiple feed distillation columns

Analytical equations for determining the minimum reflux ratio of multiple feed distillation columns are presented by using a factor method. For the method, a factor which converts feed flow to minimum reflux ratio is used. The factor is a function of the feed concentration and thermal condition. The calculation steps for determining minimum reflux ratio of multiple feed columns are summarized. A computer program is available (microcomputer or mainframe). Application of the factor method for minimum reflux ratio is illustrated by several examples.     

ABSORPTION OF NO BY NaClO2 SOLUTION: PERFORMANCE CHARACTERISTICS

The absorption of lean NO (200 ∼ 1000 ppm) gases in aqueous NaClO₂ solution was investigated in both a mechanically stirred vessel and a packed tower. The chemical reaction rate between NO and NaClO₂ in alkaline solution was shown to be second-order with respect to NO concentration and first-order to NaClO₂ concentration. After including mass transfer considerations, the absorption rate equation established in this work (under the condition of NaClO₂ concentration less than 1.0 M and temperature at 30°C) is given as:

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In addition, a robust design method was also used to study the performance of this de NO_x process by NaClO₂ solution in a packed tower. S/N analysis of the results indicated that the pH of liquor, NaClO₂ concentration and NaOH concentration were the major factors in affecting both NO oxidation and absorption efficiencies.     

无触角剃前齿轮滚刀优化设计

带触角的剃前齿轮滚刀，按ＪＢ４１０３—８５标准设计时，有时得不到可行解。文章介绍了在这种情况下，用无触角齿轮滚刀代替带触角的剃前滚刀，进行优化设计的方法，并取得了较好效果。