Association of size‐fractionated indoor particulate matter and black carbon with heart rate variability in healthy elderly women in Beijing

Associations between size‐fractionated indoor particulate matter (PM) and black carbon (BC) and heart rate variability (HRV) and heart rate (HR) in elderly women remain unclear. Twenty‐nine healthy elderly women were measured for 24‐hour HRV/HR indices. Real‐time size‐fractionated indoor PM and BC were monitored on the same day and on the preceding day. Mixed‐effects models were applied to investigate the associations between pollutants and HRV/HR indices. Increases in size‐fractionated indoor PM were significantly associated with declines in power in the high‐frequency band (HF), power in the low‐frequency band (LF), and standard deviation of all NN intervals (SDNN). The largest decline in HF was 19% at 5‐minute moving average for an interquartile range (IQR) increase (24 μg/m³) in PM_0.5. The results showed that smaller particles could lead to greater reductions in HRV indices. The reported associations were modified by body mass index (BMI): Declines in HF at 5‐minute average for an IQR increase in PM_0.5 were 34.5% and 1.0% for overweight (BMI ≥25 kg/m²) and normal‐weight (BMI <25 kg/m²) participants, respectively. Moreover, negative associations between BC and HRV indices were found to be significant in overweight participants. Increases in size‐fractionated indoor PM and BC were associated with compromised cardiac autonomic function in healthy elderly women, especially overweight ones.     

On speeding up an asymptotic-analysis-based homogenisation scheme for designing gradient porous structured materials using a zoning strategy

Structural and Multidisciplinary Optimization - Surrogate modeling is commonly used to replace expensive simulations of engineering problems. Kriging is a popular surrogate for deterministic...     

Microstructure and corrosion behaviors of FeCrNiBSiMox stainless steel fabricated by laser melting deposition

In this paper, FeCrNiBSiMo_x (x = 1.0, 1.5, 2.0, 2.5) stainless steels were successfully prepared using a laser melting deposition technology, with the aim to investigate the effect of Mo content on microstructure and corrosion behaviors. The results showed that the as-deposited specimens were composed mostly of α-Fe and a small amount of (Cr, Mo)₇C₃, and (Cr, Mo)₇C₃ existed in the inter-dendritic (ID) region. As the Mo content increased, grain refinement could be clearly observed, and the area of the ID region increased from 27% to 54%. The low-angle boundaries accounted for 60–70% of the grain boundaries of the as-deposited specimens. Increasing the content of Mo improved the microhardness of the as-deposited specimens from 652 HV to 813 HV. The corrosion current density of the as-deposited specimens with the Mo mass fractions of 1.0%, 1.5%, 2.0%, and 2.5% were 1.37 × 10⁻⁶, 1.02 × 10⁻⁷, 6.19 × 10⁻⁷, and 3.06 × 10⁻⁷ A/cm², respectively. The as-deposited specimen with Mo content of 1.5% had lower cumulative erosion loss and erosion loss rate than other as-deposited specimens. The FeCrNiBSiMo_x (x = 1.5) specimen exhibited excellent resistance to electrochemical corrosion and cavitation erosion.     

厚层坚硬顶板定向水力压裂强制放顶技术研究*

针对厚层坚硬顶板工作面初采期间顶板大面积悬空，初次来压步距大，矿压显现强烈，易诱发冲击地压等动力灾害的问题，依据定向水力压裂技术原理，研发了定向水力压裂成套装备，制定了顶板定向压裂施工工艺；结合西部矿区厚层坚硬顶板条件，分析注水压力、压裂层位、钻孔间距等关键参数，开展了3104工作面初采期间定向水力压裂工程实践，并通过实测顶板垮落情况和分析支架阻力，检测了实施效果。结果表明，直接顶初次垮落步距约11 m，初次来压步距平均值为31.8 m，与未处理顶板相比，初次来压步距减少了62.6%，初次来压时，矿压显现较类似工作面大幅减弱，避免了厚层坚硬顶板的大面积悬空，保证了工作面安全回采。     

Study on retrogradation of maize starch–flaxseed gum mixture under various storage temperatures

This study aimed to investigate the effect of flaxseed gum (FG) on the retrogradation of maize starch (MS) gels under different storage temperatures. In this work, MS‐FG gels with 0–0.4% FG were stored under different temperatures (–20, 4 and 20 °C). Under all storage temperatures, the addition of FG inhibited the retrogradation process of MS, suppressed the recrystallisation of starch molecules, reduced the water loss of starch gels and improved the texture of the gels. Among the three storage temperatures, ?20 °C could almost stop the starch retrogradation but leading it results in the hardest gel texture. The retrogradation of MS‐FG gels stored under 4 °C was most serious with the fastest rate of recrystallisation. When stored at 20 °C, the gels had a retrogradation degree that was lower than when they were stored at 4 °C and also had the softest texture.     

降补固态软启动装置在大型电动机起动中的应用

本文针对昆钢炼铁厂5号高炉鼓风机站及配套设施改造项目,结合电机参数、电网参数、用户要求及工程实际情况,对鼓风机电机的起动方案提出了性价比最高的方式--采用降补固态软启动装置起动。本文详细介绍了降补固态软启动装置的工作原理及特点,结合相关参数进行了电动机起动过程计算,并绘制仿真曲线,经过现场调试后顺利投入运行,对大型电动机的起动方式具有较好的推广作用。     

中国智能机械制造评价及发展研究

以中国规模以上工业企业数据库为基础，结合在智能制造主要区域调研的结果，筛选出15145家智能制造企业，经同行评议后，生成322家候选企业名单；再由资深产业专家从“开发式创新”和“探索式创新”两个方面去考察候选企业的能力，得到中国智能制造百强排行榜；随后根据行业分类，得到智能机械制造企业排行榜。在概述了智能机械制造上榜企业的基本情况后，着重分析了前20强企业，并提出了中国智能机械制造发展路径和未来的发展趋势。     

Ferulic acid reduced histamine levels in the smoked horsemeat sausage

This study assessed the effect of ferulic acid on the accumulation of histamine in traditional Xinjiang smoked horsemeat sausage. The dynamics of histamine‐producing microorganisms were monitored by PCR‐denaturing gradient gel electrophoresis (DGGE) with specific primer pairs, and histidine and histamine levels were measured by high‐performance liquid chromatography (HPLC). Relative parameters including microbiological growth, pH and moisture content were also evaluated. PCR‐DGGE provided a rapid and convenient method for detecting and identifying histamine‐producing bacteria. The results showed that ferulic acid reduced the histamine concentration and inhibited the growth of histamine‐producing bacteria during fermentation and ripening. Additionally, the inhibitory effect of ferulic acid was stronger than that of the starter culture. Therefore, ferulic acid appears to be a useful additive for manufacturing fermented sausages.     

基于微流控的人卵母细胞特性检测

人的卵母细胞特性的研究对于临床医学具有重要意义,可以通过卵母细胞的大小对其活性进行研究。采用微流控平台与MATLAB算法相结合的方法,利用微流控器件的沟道对卵母细胞进行挤压,由于卵母细胞的活性不同对于挤压的反应也不同,活性越好的卵母细胞通过沟道时变形性越好,经检测卵母细胞有很好的活性;拍摄卵母细胞发生形变与卵母细胞通过沟道的视频,利用MATLAB程序进行图像处理得到卵母细胞的大小,测得卵母细胞的直径约为170μm。这种方法有别于传统方法,在一定程度上使用了算法识别,提高了卵母细胞分析统计的准确度,提升了工作效率。由于人的卵母细胞比较珍贵,只进行了初期实验研究,证明此方法确实可行。     

Fabrication and properties of lightweight SiOC fiber-based assembly aerogels with hierarchical pore structure

Here we report a novel aerogel material assembled by the electrospun SiOC fibers with a hierarchical pore structure. The fibrous aerogels were successfully fabricated by the gel-casting and freeze-drying method using the SiOC fibers as the matrix and the silica sols as the binders. The effect of the SiOC fiber content and the silica sol content on the properties of the samples were investigated. The SiOC fibrous aerogels after calcined at 1000?°C exhibited low densities of 46.87–128.48?mg/cm³, low thermal conductivities of 0.0302–0.0440?W/m?K, high compressive strengths of 18–167?kPa and relatively high specific surface areas of 12.48–34.87?m²/g. Such unique fibrous aerogel materials are foreseen as the promising high-temperature insulators, absorbents and supports.