生物质纤维和改性木质素对聚乳酸结晶性能的影响

采用改性木质素(MZS)作为成核剂,生物质纤维(BF)作为增强剂,通过双螺杆挤出机制备了生物降解的聚乳酸(PLA)/BF/MZS材料。采用差式扫量热仪(DSC)、电子万能试验机和扫描电子显微镜(SEM)分析了BF和MZS对PLA材料性能的影响。结果表明,BF和MZS有效提高了PLA的结晶能力和力学性能。当BF和MZS的含量分别为15%和1%时,PLA材料结晶度提高至67.1%,在50℃/min降温速率下仍具有较高的结晶能力。105℃等温结晶时,15%BF和1%MZS的PLA材料半结晶时间降低至9.0 s,比纯PLA缩短了72.2%。当PLA含有3%BF和1%MZS时,拉伸强度和冲击强度分别为70.1 MPa和7.4 kJ/m^2,比纯PLA分别提高了7.8%和10.4%,根据SEM显示,当BF含量为3%时,在PLA材料中分布较均匀。     

剂油比对煤焦油沥青质加氢过程的影响

以中低温煤焦油沥青质为原料,采用NiMoW/γ-Al_2O_3商业催化剂,在反应温度380℃、反应压力8 MPa和反应时间1.5 h条件下,分别在不同剂油质量比(1∶25、1∶20、1∶15、1∶10)条件下进行加氢实验,通过采用元素分析、FT-IR、XRD、~1H-NMR和XPS等分析表征手段,考察不同剂油质量比对中低温煤焦油沥青质加氢转化过程的影响。结果表明,随着剂油质量比的增加,沥青质转化率提高,加氢产物分布也发生大幅变化,沥青质和芳香分轻质化转化为饱和分。但随着剂油质量比的进一步提高,同时也发生了更多的裂化反应和缩合反应,剂油质量比在合适范围能够很好地起到加氢轻质化且抑制结焦的效果。     

一种基于FPGA的可变速率帧结构设计与实现

在简述V.35接口的基础上针对V.35接口速率可变的应用需求提出了一种速率可变的帧结构,该帧结构可支持N×64kb/s(3≤N≤32)速率,从而在V.35接口上实现了多种速率的低速业务传输.     

Synthesis and Characterization of Co Nanocomposite Based on Poly(benzimidazole-amide) Matrix and Their Behavior as Catalyst in Oxidation Reaction

2,6-Bis(5-amino-1H-benzimidazol-2-yl)pyridine was prepared and characterized by Fourier transform infrared spectroscopy, elemental analysis, ¹H-NMR, and ¹³C-NMR spectroscopic methods. Then a new poly(benzimidazole-amide) was synthesized by polymerization of the corresponding diamine and isophthalic acid. The obtained poly(benzimidazole-amide) exhibited good yield and high thermal stability. Due to the existence of benzimidazole moieties in polymer’s structure, it has the tendency to form complexes with metal ions. So, a new poly(benzimidazole-amide)/Co nanocomposite was prepared. Morphological studies revealed that metal nanoparticles were dispersed in the polymer matrix without any aggregation. poly(benzimidazole-amide)/Co nanocomposite was used as a catalyst in the oxidation of ethyl benzene to acetophenone with tert-butyl hydroperoxide.     

Photochemical Reactions in Supramolecular Assemblies of Gels: Dimerizations and Polymerizations via Pericyclic Reactions

Gel state reactions offer new direction for the reactivity of the organic molecules or metal‐organic materials upon photoirradiation with shorter reaction times and high yields compared to solid and solution states. The restricted molecular movement among the molecules in the soft solids control the stereoselectivity of the photoproducts in the gel state reactions. To date, most of the strategies based on self‐assembly have been demonstrated in the solid state, in particular for [2+2] reactions of olefins and polymerization reactions of diacetylenes via 1,4 addition. The soft materials are of emerging materials in recent days given their many applicative day‐to‐day aspects. This review gives a glimpse of recent reports on pericyclic reactions in the gel state that are designed based on the self‐assembly concept. Also it highlights how such reactions accompany the physical changes in the structure of the gels and stereo controlled products with high yields.     

Chemical-Shift Perturbations Reflect Bile Acid Binding to Norovirus Coat Protein: Recognition Comes in Different Flavors

Bile acids have been reported as important cofactors promoting human and murine norovirus (NoV) infections in cell culture. The underlying mechanisms are not resolved. Through the use of chemical shift perturbation (CSP) NMR experiments, we identified a low-affinity bile acid binding site of a human GII.4 NoV strain. Long-timescale MD simulations reveal the formation of a ligand-accessible binding pocket of flexible shape, allowing the formation of stable viral coat protein–bile acid complexes in agreement with experimental CSP data. CSP NMR experiments also show that this mode of bile acid binding has a minor influence on the binding of histo-blood group antigens and vice versa. STD NMR experiments probing the binding of bile acids to virus-like particles of seven different strains suggest that low-affinity bile acid binding is a common feature of human NoV and should therefore be important for understanding the role of bile acids as cofactors in NoV infection.     

Effect of strain rate on the dynamic compressive mechanical behaviors of rock material subjected to high temperatures

Strain rate is not only an important measure to characterize the deformation property, but also an important parameter to analyze the dynamic mechanical properties of rock materials. In this paper, by using the SHPB test system improved with high temperature device, the dynamic compressive tests of sandstone at seven temperatures in the range of room temperature to 1000 °C and five impact velocities in the range of 11.0–15.0 m/s were conducted. Investigations were carried out on the influences of strain rate on dynamic compressive mechanical behaviors of sandstone. The results of the study indicate that the enhancement effects of strain rates on dynamic compressive strength, peak strain, energy absorption ratio of sandstone under high temperatures still exist. However, the increase ratios of dynamic compressive strength, peak strain, and energy absorption ratio of rock under high temperature compared to room temperature have no obvious strain rate effects. The temperatures at which the strain rates affect dynamic compressive strength and peak strain most, are 800, and 1000 °C, respectively. The temperatures at which the strain rates affect dynamic compressive strength and peak strain weakest, are 1000 °C, and room temperature, respectively. At 200 and 800 °C, the strain rate effect on energy absorption ratio are most significant, while at 1000 °C, it is weakest. There are no obvious strain rate effects on elastic modulus and increase ratio of elastic modulus under high temperatures. According to test results, the relationship formula of strain rate with high temperature and impact load was derived by internalizing fitting parameters. Compared with the strain rate effect at room temperature condition, essential differences have occurred in the strain rate effect of rock material under the influence of high temperature.     

燃料电池空气电极的孔道结构调控

燃料电池是将化学能转化成电能的装置，其空气电极催化层的设计，既要包含丰富的、易于接近的反应活性位，也要具备高度连通的电子、质子以及反应物、产物传质通道，因此电极必须具有特定三维几何结构形貌和有序分布的各功能化孔道，确保催化活性位得以充分利用以及反应可以连续进行。针对催化剂孔道的几何结构调控，本文调研了最近报道的一系列研究工作，从模板法、高温相变法、模板/相变复合方法以及基于金属有机框架材料进行孔道设计等四种主要方法出发，综述了该领域的最新研究进展。