高导热炭基功能材料研究进展

与传统的金属导热材料相比,炭基功能材料具有热导率高、密度小、耐高温、比强度和比模量高等优点,因而备受关注.主要介绍了近年来碳纤维(CF)及其复合材料、碳纳米管(CNTs)复合材料、泡沫碳、高取向热解石墨(HOPG)等高导热炭基功能材料的研究进展.     

虫草头孢提取物Fr.8组分对HepG-2胰岛素抵抗的改善作用

为探讨虫草头孢正己烷分离组分Fr.8对高胰岛素诱导的HepG-2细胞胰岛素抵抗的改善作用,作者建立了稳定的胰岛素抵抗细胞模型,并检测了Fr.8组分对胰岛素抵抗细胞(HepG-2/IR)的葡萄糖消耗、葡萄糖摄取及相关基因转录和蛋白质表达的影响。结果显示,5μmol/L胰岛素是诱导细胞成为HepG-2/IR的最佳作用浓度;Fr.8组分在无细胞毒性范围内可显著增加HepG-2/IR对葡萄糖的消耗及摄取;Fr.8(25μg/mL)可明显上调IR、IRS1、IRS2、Glut2、AMPKαmRNA的表达水平,并上调IR、IRS、Glut2、p-AMPKα、p-AKT蛋白质的表达。研究表明,虫草头孢Fr.8可改善HepG-2胰岛素抵抗,其机制可能与胰岛素受体及底物、葡萄糖转运蛋白2、pAMPKα和p-AKT蛋白的激活有关。     

天麻蜜环提取物的抗炎活性

天麻蜜环是一种具有良好药用功效的传统药食用菌,然而关于天麻蜜环抗炎活性的研究甚少。作者探索了天麻蜜环的抗炎活性,为开发利用天麻蜜环的抗炎功效以及从中寻找新的天然抗炎化合物提供科学依据。采用MTT法检测提取物的细胞毒性,实验结果显示,仅天麻蜜环正己烷、氯仿高剂量提取物（300 μg/mL） 具有轻微细胞毒性（对细胞活力的抑制率分别为10.7%和17%）,其余各剂量提取物均无细胞毒性;采用脂多糖（LPS） 刺激小鼠单核巨噬细胞RAW264.7,分别用天麻蜜环正己烷、氯仿、乙酸乙酯、正丁醇提取物（0,30,100,300 μg/mL）干预以检测其抗炎活性,实验结果显示,天麻蜜环正己烷、氯仿、乙酸乙酯提取物均能呈剂量依赖性地抑制LPS诱导的炎症介质一氧化氮（NO）和炎症因子肿瘤坏死因子（TNF-α）、白介素6（IL-6）、白介素1β（IL-1β）的过量分泌,其中乙酸乙酯提取物既具有良好的安全性又有显著的抗炎活性。     

基于钝齿棒杆菌argGH启动子改造的L-瓜氨酸高效合成

L-瓜氨酸是尿素循环的重要中间体,在argGH编码酶的催化下易分解为L-精氨酸,在微生物体内难以大量积累。作者通过启动子替换手段,以弱启动子P-dapAB6替换调控argGH表达的启动子P-argG,构建了弱化L-瓜氨酸分解代谢途径的重组菌株Corynebacterium crenatum H-7-PdapAB6:argGH。重组菌株的转录水平和酶活力结果显示,重组菌株分解途径中argG和argH的基因表达水平下调,精胺琥珀酸合成酶ASS(argG编码)和精胺琥珀酸裂解酶ASL(argH编码)酶活分别降低91.80%和55.35%。摇瓶发酵结果表明,L-瓜氨酸的产量、糖酸转化率和生产强度分别为33.85 g/L、0.25 g/g和0.34 g/(L·h),较原始菌株分别提高了4.91、5.00和4.86倍。通过启动子替换策略,构建了L-瓜氨酸分解代谢途径弱化的工程菌株,初步实现了L-瓜氨酸的高效合成。     

一种基于电磁超材料的大规模天线阵列天线罩解耦技术

文中设计了一种去耦天线罩,为解决紧凑排列的大规模天线阵列中相邻端口隔离度较低的问题提供了参考.天线罩主体是一层具有低介电常数和低损耗性的介质板,其上印刷了周期性排列的金属贴片结构.通过调整金属贴片的形状以及天线罩到天线阵列的距离,使天线罩产生的反射波与阵中的耦合波幅度相同、相位相反,二者相互抵消,达到增加阵中端口间隔离...     

西索米星生产菌株的诱变选育及工艺优化

利用原生质体常压室温等离子体（ARTP）诱变方法选育西索米星高产菌株,经诱变筛选获得一株高产菌株I4-10,其西索米星的生物效价达到1 389 U/mL,较原始菌株提高了35.4%。通过对高产菌株I4-10进行碳源、氮源优化,确定可溶性淀粉和牛肉粉是突变菌株I4-10的最适碳源和氮源。进一步采用响应面实验设计方法优化发酵培养基,结果表明黄豆饼粉和DL-蛋氨酸的添加量为显著影响因素,经优化其最适添加质量浓度分别为32.78 g/L和1.75 g/L。在此最适工艺下,西索米星的生物效价提高至1 849 U/mL,较原始菌株提高了80%。最后对原始菌及高产突变株中西索米星代谢途径及菌株生长相关的关键酶进行转录水平比较分析,初步解析了突变菌株I4-10高产西索米星的机制。     

Influence of fullerenes on the thermal and flame-retardant properties of polymeric materials

At present, the application of fullerene in polymer materials has become an attractive issue. Fullerene can enhance the thermal and flame-retardant properties of polymers due to its high capacity to trap free radicals. Fullerene also has good synergistic effect with inorganic metal flame retardant, intumescent flame retardant, brominated flame retardant (BFR), clay, carbon nanotubes, graphene oxide, and so on. In this review, the impact and mechanism of fullerene and its derivatives on the thermal and flame-retardant properties of polymeric materials are discussed. And the prospect of fullerene in flame-retardant polymer composites is also briefly introduced by analyzing the research progress in the recent years. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 47538.     

Fabrication of fullerene decorated by iron compound and its effect on the thermal stability and flammability for high-density polyethylene

Fullerene decorated by iron compound (C₆₀-Fe) is fabricated via solution reaction and characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), wide-angle X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Upon incorporating C₆₀-Fe into high-density polyethylene (HDPE) matrix by melt blending, the thermal and thermo-oxidative stability of HDPE are considerably increased, the oxidative induction time (OIT) is dramatically extend. When the concentration of C₆₀-Fe reached 5 wt%, the onset degradation temperature in air increased from 352°C to 422°C, and the OIT dramatically delayed from 4.5 to 47.8 minutes. Moreover, from microscale combustion calorimetry (MCC), C₆₀-Fe can reduce the peak heat release rate (PHRR), heat release capacity (HRC), and total heat release (THR) values of the composites, all of which are very important parameters for evaluating the fire retardancy of a polymeric material.     

Application of kinetics and computational fluid dynamics in pinene isomerization

A reliable kinetic model to describe the effects of various factors on the reaction rate and selectivity of pinene isomerization is developed. Furthermore, computational fluid dynamics(CFD) is applied to simulate the solid–liquid dispersion in reactor. The catalyst Ti M is obtained by improving the composition and structure of hydrated titanium dioxide. The kinetic equation of pinene isomerization is deduced based on reaction mechanism and catalyst deactivation model. The kinetic equation of pinene isomerization reaction is fitted, and the results show that the fitted equation is correlated with the experimental data. The rate and selectivity of pinene isomerization reaction are affected by the amount of catalyst, deactivation of catalyst, structure of catalyst, reaction temperature and water content of catalyst. The solid–liquid distribution of the reactor is calculated by computational fluid dynamics numerical simulation, and the solid–liquid dispersion in commercial scale reactor is more uniform than that in lab-scale reactor.     

鞍钢低碳清洁高效高炉炉料结构发展战略研究

为了提高鞍钢股份有限公司高炉利用系数、降低燃料消耗和推动绿色发展,梳理、分析了目前高炉原料工艺结构方面存在的问题与短板,并提出了具体技术措施和低碳清洁高效预期目标.针对高炉炉料结构的发展,提出了提铁降硅、减少中型规模烧结产线、MgO质酸性球团逐步取代普通酸性球团、熔剂性球团关键工艺技术开发与产业化4条战略判断和开展鞍钢自产铁精矿合理品位系统优化技术研究、新建大型带式机熔剂球团生产线、国内外两种铁矿资源科学合理配置利用3条建议.