关于"三要素"的重新认识

求解一阶电路的三要素法似乎是很熟悉的课题。但是对它的认识是否到位、文字的表达是否严谨还需要进一步探讨,对三要素求解方法进行了分析和证明。     

硅藻土胎模成形刀具设计

通过硅藻土胎模的加工实践,分析了硅藻土特点及其切削性能,设计了加工硅藻土胎模成型曲面的成形刀具,不但提高了胎模加工表面的质量,而且使硅藻土胎模成型曲面的加工效率提高了几十倍。     

不同直径匹配度封堵气囊的工作机理和试验验证

为研究气囊作为临时性封堵装置在隧道工程中的应用情况,建立其受力分析模型,得到了气囊内压和形状随外压增长的变化规律,得到了两种失效模式和正常工作时需要满足的3个控制条件,特别是外压不能大于内压这一独特的控制条件.由于气囊直径与隧道匹配度的大小直接影响封堵效果,因此确定直径允许误差范围在工程设计中至关重要.分别采用直径大于、等于、小于隧道直径的3种气囊进行堵气和堵水的模型试验,得到不同直径匹配度的气囊在气压和水压作用下的变形规律、内外压关系及失效极限状态的控制条件.试验结果表明:直径适中的气囊匹配性最好,气囊的变形和失效模式完全符合理论公式;直径略偏大的气囊若不出现初始贯通的褶皱,其封堵效果和失效模式与直径适中的气囊类似;直径偏小的气囊,由于一部分内压用于抵消使其膨胀至贴紧隧道壁所产生的材料拉力,容易导致其摩阻力不足而在外压作用下产生整体滑动.据此提出了气囊制作误差允许范围上下限的标准,为气囊制作过程中的误差控制提供依据.     

寨上矿区钻井液漏失的预防及处理

寨上矿区岩性复杂且破碎,施工过程中易出现钻井液漏失现象,给正常钻进带来困难。本文结合矿区ZK929钻孔遇到的钻井液漏失问题,分析了钻井液漏失的原因,并给出了治理钻孔漏失的堵漏措施和预防方法。     

Effect of SiO2 content on performance of polypropylene separator for lithium‐ion batteries

Composite separators are prepared by introducing SiO₂ nanoparticles on both sides of polypropylene separator with various SiO₂ contents through a dip‐coating process, where polyvinylidene fluoride‐hexafluoropropylene is used as binder. Coated layers have highly porous structure, which is quantitatively analyzed by air permeability. Compared to pristine separator, composite separators show significant lower Gurley value, reduced thermal shrinkage, higher liquid electrolyte uptake, better mechanical properties, and better cell performance such as discharge C‐rate capability and cycle performance. The influence of SiO₂ content on these properties is also studied, and the best SiO₂ content is given. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41156.     

Influence of different thawing methods on physicochemical changes and protein oxidation of porcine longissimus muscle

The objective of the present study was to elucidate the physicochemical changes and protein oxidation of porcine longissimus muscle as influenced by different thawing methods. Five kinds of thawing methods, comprising of refrigerator thawing (RT, 4 °C), ambient temperature thawing (AT, 20 °C), water immersion thawing (WT, 14 °C), lotic water thawing (LT, 9 °C), and microwave thawing (MT), were used. There were significant effects on the porcine meat quality due to different thawing methods. RT had the least quality loss and the physicochemical characteristics of pork were closer to fresh muscle than the other thawing methods. MT significantly increased thawing loss, cooking loss, cutting force, carbonyl content, and TBARS (thiobarbituric acid-reactive substances) value, but decreased a* value and Ca-, K-ATPase activities (P < 0.05). Microstructural changes in experimental muscle showed that MT induced visibly larger gap between muscle fibers and tore more muscle fiber bundles compared to the other thawing methods. The reduction of Ca- and K-ATPase activities (P < 0.05) of myofibrillar protein was consistent with the increases in carbonyl content and TBARS value (P < 0.05). The results demonstrated all the thawing methods could cause porcine lipid and protein oxidation. Gel electrophoresis patterns of porcine muscle displayed that different thawing methods did not induce obvious protein aggregates and fragments.     

Integrated LaB6/g-C3N4 solar absorber for solving dye accumulation during solar steam generation

Solar steam generation has attracted considerable interest due to its easy accessibility and sustainability. However, dye molecules were gradually concentrated on bulk water or the surface of solar absorbers during the disposal of dye wastewater. Herein, LaB₆/g-C₃N₄ composites were immobilized on porous cotton cloth, served as a solar absorber resistant to dye clogging. The optimal solar absorber possessed solar harvesting of 92.3% and showed great application potential in the field of the treatment of dye wastewater. This study presented a new approach for the treatment of dye wastewater.     

《强夯地基处理技术规程》CECS279:2010编制与内容解读

在总结我国强夯施工技术发展与经验的基础上,编制了《强夯地基处理技术规程》CECS279:2010,并已经发布.对规程的主要内容进行了介绍,包括总则,术语和符号,基本规定,设计,施工,质量检测和验收等内容.     

UPLC-ESI-MS/MS for determining trans- and cis-vitamin K1 in infant formulas: method and applications

A simple and sensitive method of determining vitamin K₁ isomers (cis-and trans-forms) was developed for routine monitoring of supplemented infant formulas. The proposed method involves the applications of the lipase hydrolysis and the liquid-to-liquid extraction. After the hydrolysis and extraction procedures, the vitamin K₁-enriched extract was directly injected into the ultra-performance liquid chromatography–tandem mass spectrometry system (UPLC-MS/MS). The components were detected using electrospray ionization (ESI) in positive-ion and quantified by multiple-reaction monitoring (MRM) mode. trans-vitamin K₁ was separated from the biologically inactive cis-isomer through a C₃₀ column (4.6?×?150?mm, 3?μm), and vitamin K₁-d₇ was used as an internal standard. Calibration curves were linear over the range of 9.3–464.75?ng?ml^?1 for trans-vitamin K₁ (r ²?>?0.999) and 1.71–85.25?ng?ml^?1 for cis-vitamin K₁ (r ²?>?0.999). The limit of detection for trans- and cis-vitamin K₁ was 0.011?μg 100?g^?1 and 0.01?μg 100?g^?1. The limit of quantification was 0.037?μg 100?g^?1 and 0.031?μg 100?g^?1, respectively. The intra- and inter-batch variations (RSD%) were less than 5?%. The proposed method was applied to determine vitamin K₁ isomers in milk-based, soy-based and rice-based infant formulas, and the cis-vitamin K₁ isomer contributes to 7.05–17.21?% of the total vitamin K₁ in certain infant formulas.