Polydimethylsiloxane/monomer casting nylon copolymers: Preparation,flame-retardant properties,and wear-resistant properties

In order to improve the toughness, wear resistance, and combustion properties of the monomer casting nylon (MC nylon) materials, the polydimethylsiloxane (PDMS) segment is bonded to the nylon molecular chain by copolymerization. PDMS/MC nylon copolymers are prepared via in situ anionic polymerization with macro-activator based on PDMS terminated with hexamethylene diisocyanate. The effects of different macro-activator content on the mechanical properties, water absorption, thermal stability, friction and wear properties, and combustion properties of the copolymers are characterized. The results show that the impact strength of the copolymer improves significantly (optimally increases by 2.6 times) and the water absorption rate decreases with the increase of PDMS content. The introduction of the silicon–oxygen structure reduces the peak heat release rate of copolymer materials (optimally decreases about 28.7%), while it promotes the decomposition of the system, resulting in a slight decrease in the thermal stability of the materials. Adding 5 wt % PDMS can decrease the wear loss of MC nylon from 6.2 mg of pure nylon to 1.6 mg. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48753.     

Effects of clearance flow on the characteristics of centrifugal pump under low flow rate

Journal of Mechanical Science and Technology - The Reynolds averaged Navier-Stokes equations and the shear stress transport k-w turbulence model are employed to simulate the centrifugal pump with...     

25Cr2Ni4MoV锻轴制造工艺研究

对25Cr2Ni4MoV钢锻轴的冶炼、锻造、热处理工艺进行研究,并通过超声检测和力学性能检验,充分证明了其冶炼、锻造、热处理工艺的可行性。在生产实践中,成功地制造出了4支该材质的60 MW空冷发电机转子。     

第二代高温辊式破碎机用辊轴的研究

根据傅里叶定律、牛顿冷却定律以及辊式破碎机辊轴的有关参数建立了辊轴的热传导模型,模拟计算了不同工况下的辊轴使用情况。在600℃工况温度时,辊轴采用风冷、使用40Cr材料可以安全使用;但在850℃工况温度时,辊轴材料需更换为0Cr18Ni9,或辊轴材料不变,冷却方式改用水冷,方可满足使用安全。     

负压吸引技术应用于大面积烧伤患者围术期的效果探究

目的:探究环磷酸腺苷联合负压吸引技术应用于大面积烧伤患者围术期的效果及肾保护作用探究。方法:选择2018年12月到2020年12月于医院治疗的120例大面积烧伤患者为研究对象,以随机数字表法对患者分组,60例患者为研究组,60例患者为对照组,对照组给予负压吸引技术治疗,研究组在此基础上给予环磷酸腺苷治疗,治疗前、后测定两组患者干扰素-γ(IFN-γ)、白细胞介素-2(IL-2)、白细胞介素-10(IL-0)、白细胞介素-6(IL-6)、可溶性血管细胞粘附分子-1(sVCAM-1)、一氧化氮(NO)、内皮素(ET-1)、血管内皮生长因子(VEGF)、胱抑素C(Cys-C)、肌酐(Scr)、血尿素氮(BUN)、肾损伤分子-1(KIM-1)水平,记录两组患者手术时间、麻醉苏醒时间、住院时间。结果:研究组IFN-γ、IL-6水平低于对照组(P<0.05),研究组患者IL-2、IL-10水平高于对照组(P<0.05),研究组NO、VEGF水平高于对照组(P<0.05),研究组患者sVCAM-1、ET-1水平低于对照组(P<0.05),研究组患者Cys-C、Scr、BUN、KIM-1水平低于对照组(P<0.05),研究组手术时间低于对照组(P>0.05),研究组麻醉苏醒时间、住院时间低于对照组(P<0.05)。结论:环磷酸腺苷联合负压吸引技术应用于大面积烧伤围术期患者,可降低患者IFN-γ、IL-6水平,提升患者IL-2、IL-10水平,抑制患者炎症,改善患者血管内皮功能,降低患者Cys-C、Scr、BUN、KIM-1水平,减少患者肾功能损伤,减少患者麻醉苏醒时间及住院时间。     

Sustainability accounting for the construction and operation of a plant‐scale solar‐biogas heating system based on emergy analysis

Domestic heating systems have long been playing a significant role in China's energy structure. The sustainability of a hybrid solar‐biogas heating system (SBHS) under various feedstock fermentation scenarios was evaluated using emergy analysis. Representative emergy indices such as transformities, emergy yield ratio (EYR), environmental loading ratio (ELR), emergy sustainability index (ESI), ratio of waste treatment (%W), feedback yield ratio (FYR), and emission mitigation intensity (EMI; g/10¹⁰ sej) were selected to evaluate the sustainability performance of different feedstock scenarios including cow dung (CD), swine manure (SM), and poultry manure (PM). The results showed that PM fermentation scenario had greater market competitiveness, lower environmental pressure, better sustainability, and self‐organizing ability than the other two options. However, both the emergy efficiency and the CO₂ emissions mitigation intensity of PM scenario were worse than that of the SM and CD. Moreover, compared with other biogas systems and traditional agricultural systems, the hybrid SBHS was proved to be a promising mode for the treatment of rural manure waste with favorable economic benefits and environmental sustainability.     

高速公路工程造价控制SD模型与应用研究

高速公路工程投资规模大,其工程造价广为社会公众关注,因高速公路投资控制中"三超"问题突出,亟需探寻高速公路事前、主动的工程造价控制路径和方法.结合文献统计确立设计阶段工程造价控制指标体系,基于SD理论,绘制因果关系图和系统存量流量图,进而构建高速公路工程造价控制的SD模型,采用定性与定量相结合的方法研究工程造价控制的系统结构;并以JS高速公路项目为例,实证检验工程造价控制SD模型的先进性和适用性,为高效、精准控制高速公路工程造价提供新的思路和方法,也为高速公路项目投资决策提供科学依据和方法支持.     

中国保健酒的历史发展及研究进展

保健酒是中国的传统酒类饮品之一，通常是将药食两用的动植物原料经浸提、渗漉、提取等方式加工而成，其中包含了多糖、黄酮、皂苷等多种原料有效成分，具有一定的养生作用。随着经济的发展和人们对健康的重视，保健酒的需求量逐渐增加。该文回顾了中国保健酒的发展历史，总结了保健酒工艺、成分鉴定以及功能的研究进展，并根据现有的研究，对保健酒行业的发展前景进行了展望。