抗磨铸铁强化变质剂的研究

介绍了关于含有B、Ti、Sr等合金及复合盐对抗磨白口铸铁变质效果的研究情况。并通过实验结果表明，采用复合盐类变质处理可以改善高铬铸铁的碳化物形貌，同时大大提高了冲击韧性。     

NFC苹果浊汁褐变与品质相关性研究

褐变是果汁品质劣变的重要因素之一.通过模拟NFC苹果浊汁开封后在未完全密闭状态下,于4℃和20℃短期贮藏期间的自然褐变过程,探讨苹果浊汁褐变过程与营养及风味变化的关系.结果表明,NFC苹果浊汁贮藏过程中褐变程度受贮藏温度和时间的直接影响.在两种贮藏温度下,果汁颜色均随贮藏时间延长不断加深,总酚和维生素C含量逐渐下降;可溶性固形物含量降低和可滴定酸含量增高导致糖酸比下降.20℃贮藏期间,果汁品质劣变迅速;4℃贮藏初期,果汁品质变化不明显,但在后期劣变速度明显加快.NFC苹果浊汁在贮藏前期芳香族化合物、氮氧化合物等挥发性风味物质有所减少,而在贮藏后期碳氢化合物、无机硫化物、烷烃类和脂肪族类物质逐渐增加.褐变与NFC苹果浊汁品质指标的相关性分析表明:冷藏条件下褐变程度与浊汁口味和挥发性风味的相关性更强,而常温贮藏下与浊汁营养物质含量的相关性更强.研究结果可丰富果汁贮藏机理,以期为苹果浊汁加工及开封后短期贮藏过程中品质变化研究及调控提供理论借鉴.     

双金属管复合技术的研究进展(下)

介绍了国内外双金属管的发展现状,各种复合技术的生产工艺流程及其优缺点。重点从技术优势、创新性、应用种类等方面对离心工艺冶金熔合技术进行了详细的阐述,并对离心铸造复合管坯容易出现的缺陷进行了分析,提出了解决措施,对离心铸造冶金熔合技术的发展前景和研究趋势进行了展望。     

Curing behavior and processability of BMI/3‐APN system for advanced glass fiber composite laminates

The prepolymers containing bismaleimide (BMI) and 3‐aminophenoxyphthalonitrile (3‐APN) were prepared through simple solution prepolymerization, and the corresponding curing behaviors and processability were investigated by differential scanning calorimetry and dynamic rheological analysis. The results showed that the processability of the prepolymers could be controlled by temperature and time on processing, also depended on the relative content of 3‐APN and BMI. The possible curing reactions of the prepolymers were studied by Fourier transform infrared spectroscopy, which involved the Michael addition between BMI and 3‐APN and self‐polymerization of BMI or 3‐APN. The resulting polymers displayed high thermo‐oxidative stabilities (T_5% > 425 °C) and good adhesion capability. Furthermore, BMI/3‐APN systems were employed to prepare BMI/3‐APN/glass fiber (GF) composite laminates and their morphological, mechanical, and electrical stable properties were also investigated. The BMI/3‐APN/GF laminates exhibited the improvement of the mechanical properties (the maximum flexural strength is 633.5 MPa and flexural modulus is 38.7 GPa) compared with pristine BMI/GF laminates because of the strong interfacial adhesions between GF and matrices, which was confirmed with SEM observations. This study provides a concise strategy for diversifying the preparation of BMI/3‐APN prepolymers to obtain advanced GF composite laminates with various properties which have potential applications in industrial manufacture or electronic circuit, and so on. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43640.     

厚壁离心管坯轴向裂纹分析

运用有限元分析软件ANSYS对材质为21CrMo10的管坯,在不同工艺参数下的温度场和热应力场进行了分析,结合实际检验得出:出现轴向裂纹的原因在于涂层太薄、管坯横截面的温度梯度大于了8℃/mm,随着涂层厚度的减小、浇注温度的升高,厚壁管坯内壁的热应力有增加的趋势.     

Mycoplasma bovis MBOV_RS02825 Encodes a Secretory Nuclease Associated with Cytotoxicity

This study aimed to determine the activity of one Mycoplasma bovis nuclease encoded by MBOV_RS02825 and its association with cytotoxicity. The bioinformatics analysis predicted that it encodes a Ca²⁺-dependent nuclease based on existence of enzymatic sites in a TNASE_3 domain derived from a Staphylococcus aureus thermonuclease (SNc). We cloned and purified the recombinant MbovNase (rMbovNase), and demonstrated its nuclease activity by digesting bovine macrophage linear DNA and RNA, and closed circular plasmid DNA in the presence of 10 mM Ca²⁺ at 22–65 °C. In addition, this MbovNase was localized in membrane and rMbovNase able to degrade DNA matrix of neutrophil extracellular traps (NETs). When incubated with macrophages, rMbovNase bound to and invaded the cells localizing to both the cytoplasm and nuclei. These cells experienced apoptosis and the viability was significantly reduced. The apoptosis was confirmed by activated expression of phosphorylated NF-κB p65 and Bax, and inhibition of Iκβα and Bcl-2. In contrast, rMbovNase^Δ181–342 without TNASE_3 domain exhibited deficiency in all the biological functions. Furthermore, rMbovNase was also demonstrated to be secreted. In conclusion, it is a first report that MbovNase is an active nuclease, both secretory and membrane protein with ability to degrade NETs and induce apoptosis.     

Synthesis and characterization of poly(ethylene glycol)-b-poly(l-histidine)-b-poly(l-lactide) with pH-sensitivity

In this paper, amphiphilic biodegradable methoxy-poly(ethylene glycol)-poly(l-histidine)-poly(l-lactide) (mPEG–PH–PLLA) triblock copolymers with pH sensitivity were synthesized. The properties of mPEG–PH–PLLA triblock copolymers were investigated by GPC, ¹H NMR, DSC, TGA, XRD and polarized optical microscopy. The results showed that the thermal properties of the triblock copolymers varied with the chain length of PH blocks. The glass transition temperatures (Tg) of the triblock copolymers increased with increasing poly(l-histidine) chain length. The morphologies of PLLA crystals changed from spherulite to dendritic crystal. Moreover, the crystallization rate of triblock copolymers was faster than that of PLLA homopolymer. The pH sensitivity of the self-assembled mPEG–PH–PLLA nanoparticles was investigated. The mean diameter and morphology of the nanoparticles were characterized by DLS, AFM and TEM. The results showed that the mean diameter of mPEG₄₅–PH₃₀–PLLA₈₂ nanoparticles in pH = 5.0 was smaller than that in pH = 7.4.     

1Cr18Ni9Ti不锈钢晶间腐蚀试验研究

通过对1Cr18Ni9Ti不锈钢无缝钢管晶间腐蚀试验的研究,从多个方面分析造成试样材质不合格的原因,进而总结出在冶炼18-8型不锈钢时化学成分控制的要点.     

城市建设强度与热岛的相关性——以重庆市开州区为例

城市建设强度是城市热岛形成与演变的主要驱动因素,为了揭示两者之间的量化关系,以重庆市开州区为例,在用地地块、规则网格和建筑斑块3个空间尺度上,使用ArcGIS提取地表温度（LST）与建设强度指标,利用SPSS分析其相关性并构建多元回归模型。结果表明：用地地块尺度上,LST与绿化率、建筑密度和容积率之间均呈现显著的负相关,与建筑底面积和总建筑面积之间均呈现显著的正相关。规则网格尺度序列上,LST与建设强度各指标之间的相关性系数随网格面积的增大而增大,在840 m网格时达到最大值;总体上LST与绿化率之间呈显著的负相关,与建筑密度和容积率之间呈显著的正相关。建筑斑块的尺度上,LST与建筑层数之间有显著的负相关关系,与总建筑面积之间有显著的正相关关系。城市建设强度直接或间接影响了城市热岛的形成与演变,而相关分析发现,建设强度指标并非都与LST之间呈正相关关系,这表明城市热岛除受建设强度的影响外,还受区域气候、城市形态、城市性质、交通方式以及建筑材质与色彩等多种因素的协同影响,是一个非线性的复杂过程。     

Polarization‐Sensitive Ultraviolet Photodetection of Anisotropic 2D GeS2

Polarization‐sensitive photodetection in the UV region is highly indispensable in many military and civilian applications. UV‐polarized photodetection usually relies on the use of wide bandgap semiconductors with 1D nanostructures requiring complicated nanofabrication processes. Although the emerging anisotropic 2D semiconductors shed light on the detection of polarization with a simple device architecture, bandgaps of such reported 2D semiconductors are too small to be applied for visible–blind UV‐polarized photodetection. Here, germanium disulfide (GeS₂), the widest bandgap (>3 eV) in the family of in‐plane anisotropic 2D semiconductors explored to date, is introduced as an ideal candidate for UV‐polarized photodetection. The structural, vibrational, and optical anisotropies of GeS₂ are systematically investigated from theory to experiment. GeS₂‐based photodetectors show a strong polarization‐dependent photoresponse in the UV region. GeS₂ with a wide bandgap and high in‐plane anisotropy not only enriches the family of anisotropic 2D semiconductors but also expands the polarized photodetection from the current visible and near‐infrared to the brand‐new UV region.