锅炉受热面抗振隔板的计算

从锅炉受热面管道振动的原因出发,提出加装抗振隔板是消除振动最有效的方法,并给出抗振隔板选取方法及其结构和安装方法,最后给出抗振隔板及悬吊所用材料的选取。     

水溶性酚醛树脂改性离合器摩擦材料的制备与性能研究

分别采用水溶性酚醛树脂法、浸浆缠绕法和贴胶缠绕法3种工艺制备了汽车用离合器面片,研究了3种工艺对离合器面片的摩擦磨损性能、物理性能和力学性能的影响。结果表明：采用水溶性酚醛树脂工艺制备的离合器面片耐热性好,摩擦系数大小适中、热稳定性好,磨损率低,硬度、孔隙率适中,而且剪切强度和断裂应变最大,综合性能最为优异。     

用向量函数求解曲线积分和曲面积分

为了方便计算曲线积分和曲面积分,利用向量函数表示空间曲线和空间曲面,给出计算第一类曲线积分和第一类曲面积分的两个定理,并给予详细证明;最后,通过实例分析,说明其应用方法。     

A CRISPR/Cas12a-empowered surface plasmon resonance platform for rapid and specific diagnosis of the Omicron variant of SARS-CoV-2

The outbreak of the COVID-19 pandemic was partially due to the challenge of identifying asymptomatic and presymptomatic carriers of the virus, and thus highlights a strong motivation for diagnostics with high sensitivity that can be rapidly deployed. On the other hand, several concerning SARS-CoV-2 variants, including Omicron, are required to be identified as soon as the samples are identified as ‘positive’. Unfortunately, a traditional PCR test does not allow their specific identification. Herein, for the first time, we have developed MOPCS (Methodologies of Photonic CRISPR Sensing), which combines an optical sensing technology-surface plasmon resonance (SPR) with the ‘gene scissors’ clustered regularly interspaced short palindromic repeat (CRISPR) technique to achieve both high sensitivity and specificity when it comes to measurement of viral variants. MOPCS is a low-cost, CRISPR/Cas12a-system-empowered SPR gene-detecting platform that can analyze viral RNA, without the need for amplification, within 38 min from sample input to results output, and achieve a limit of detection of 15 fM. MOPCS achieves a highly sensitive analysis of SARS-CoV-2, and mutations appear in variants B.1.617.2 (Delta), B.1.1.529 (Omicron) and BA.1 (a subtype of Omicron). This platform was also used to analyze some recently collected patient samples from a local outbreak in China, identified by the Centers for Disease Control and Prevention. This innovative CRISPR-empowered SPR platform will further contribute to the fast, sensitive and accurate detection of target nucleic acid sequences with single-base mutations.     

表面活性剂增敏光度法测定水样中的微量铁

在HAc-NaAc缓冲溶液(pH=5)存在下,以邻二氮菲(phen)作显色剂,表面活性剂曲拉通X-100对Fe(II)与邻二氮菲的显色反应具有增敏作用,形成的Fe(II)-phen-Triton三元络合物呈红色,络合物的最大吸收波长为510 nm,表观摩尔吸光系数为1.2×105L.mol-1.cm-1,铁含量在0.5~12μg/mL范围内符合比尔定律,用于水样中微量铁的测定,回收率在97.1%~98.0%之间。     

静压桩与天津滨海新区土体滑动摩擦的试验研究

静压桩贯入地基时,桩侧面与土之间会产生滑动摩擦.采用改进直剪仪进行试验,研究了静压桩与天津滨海新区土体间的滑动摩擦及其时效性,得出了静压桩与土的外摩擦角及其变化规律,并总结了静压桩与土摩阻力的时效性机理.研究发现滑动摩阻力与土的类型、法向应力有关,且与法向应力近似呈直线关系;随着时间的增长,粘土和淤泥质土与桩之间的摩阻...     

Influence of medium components on elastase production using crude sources by<Emphasis Type="Italic">Bacillus</Emphasis> sp. EL31410

A newly isolated strain EL31410, producing elastase (E. C3. 4. 4. 7) with high elastolytic activity was identified asBacillus sp. In the medium optimization, it was found that wheat bran and soybean flour hydrosate were the best crude carbon and nitrogen source for enzyme production, respectively. Addition of corn steep flour can affect the bacterium growth and elastase production. A fractional factorial design was applied to study the main factors that affect the enzyme production, and central composite experimental design and response surface methodology were adopted to derive a statistical model for the effect of wheat bran and soybean flour hydrosate on elastase production. The experimental results showed that wheat bran had positive effect but soybean flour hydrosate had negative effect, on enzyme production. An initial concentration of 3.4% (w/v) wheat bran and 9.4% (v/v) soybean flour hydrosate were found to be optimal for enzyme production in batch culture. The time course of elastase production in the optimized medium composition was also described. Project (No. 300024) supported by the Zhejiang Provincial Natural Science Foundation of China     

固体低频内耗力学模型及其测量研究

综述了固体低频内耗的力学模型及其测量的研究进展.固体的内耗有滞弹性和粘弹性内耗,低频内耗常用的测量方法有自由衰减法和强迫振动法.固体内耗的典型力学模型有两参量和三参量的Voigt模型和Maxwell模型,都可用来描述固体内耗,但都有一定局限性,目前还没有一个理想的力学模型来描述粘弹性内耗,尤其是非线性粘弹性内耗.     

水泥混凝土路面脱皮露骨的原因分析及预防措施

本文从施工技术管理方面阐述了水泥混凝土路面脱皮露骨的产生原因及预防措施.     

Effects of condensed water on limestone surfaces in a marine environment

We have evaluated the effects of condensed water on limestone surfaces through a procedure that foresaw the cooling of the samples before their exposition to the open air, so that the condensation phenomena could occur easily. The effects of the condensed water were evaluated by measuring the weight change of the samples, through SEM observations and analysis of the 3-D profile, using laser profilometer. The results show the weak action of condensed water on the stone surface, particularly if compared with that of rain.