DSC and TMDSC study of melting behaviour of poly(butylene succinate) and poly(ethylene succinate)

The subsequent melting behaviour of poly(butylene succinate) (PBSU) and poly(ethylene succinate) (PES) was investigated using DSC and temperature modulated DSC (TMDSC) after they finished nonisothermal crystallization from the melt. PBSU exhibited two melting endotherms in the DSC traces upon heating to the melt, which was ascribed to the melting and recrystallization mechanism. However, one melting endotherm with one shoulder and one crystallization exotherm just prior to the melting endotherm were found for PES. The crystallization exotherm was ascribed to the recrystallization of the melt of the crystallites with low thermal stability, and the shoulder was considered to be the melting endotherm of the crystallites with high thermal stability. The final melting endotherm was ascribed to the melting of the crystallites formed through the reorganization of the crystallites with high thermal stability during the DSC heating process. TMDSC experiments gave the direct evidences to support the proposed models to explain the melting behaviour of PBSU and PES crystallized nonisothermally from the melt.     

滞后测量法在聚合物动态疲劳研究中的应用

用滞后测量法考察了mPE和EPDM改性PP在不同的负荷方式下的动态力学性能随时间的连续变化,确定了在动态应力作用下可以用临界动态应力(σd)表征材料的疲劳极限。在低于σd的应力作用下,试样可以有较长的疲劳寿命(大于10^5次),而高于σd,试样的力学性能迅速降低。随着mPE和EPDM质量分数的增加,共混物的σd降低;mPE的结晶度增加则使共混物的σd增大,疲劳性能提高。相同密度的mPE和EPDM相比,PP／mPE共混物的疲劳性能优于PP／EPDM的。     

以丙烯酸酯化聚氨酯为核的核壳粒子的制备及其对环氧树脂的增韧作用

多步反应制备了一种自乳化的丙烯酸酯化聚氨酯,然后用种子乳液聚合法制备了以丙烯酸酯化聚氨酯和丙烯酸丁酯共聚物为核、聚甲基丙烯酸甲酯为壳的核壳粒子。该粒子对环氧树脂828有很好的增韧效果,在添加量为8份(质量)时,环氧树脂的剪切强度和冲击强度分别为未改性时的2．2和3．3倍。     

可再分散聚合物粉末研究进展

介绍了可再分散聚合物粉末在国内外的应用、制备及作用机理研究现状,说明其存在耐水性能较差及价格偏高等问题,今后应进一步加强耐水性能及作用机理等方面的研究。     

笼形水合物研究与应用

介绍笼形水合物的晶体结构、性质,同时简要讨论了水合物实验和理论研究,评述了甲烷水合物作为一种潜在能源的价值;并对水合物技术的应用领域和前景进行了综述。     

MOF作模板制备多孔Au/CuxO催化剂及其CO氧化性能

采用MOF材料作模板,通过在Cu-BTC材料表面预先负载贵金属Au再热解的方法,成功制备了具有正八面体结构的新型多孔Au/Cu_xO负载型催化剂。通过降低热解环境中的O₂浓度,调节氧化时间,实现了Au/Cu-BTC氧化产物组分的调节,分别制得了Au/Cu₂O、Au/Cu₂O-CuO、Au/CuO复合催化材料。将其用于CO催化氧化,发现所有Au/Cu_xO催化剂都表现出比Cu-BTC和Au/Cu-BTC更优异的催化性能,其中由于拥有较高的比表面积、Cu₂O含量以及更好的Au的分散性,Au/Cu₂O的CO氧化活性最佳,180℃即能实现CO的完全转化。     

Effect of TeO2 on Near‐Infrared Emission from Bismuth Centers in Borogermanate Glasses

Bi‐doped xTeO₂–(60?x)GeO₂–15B₂O₃–20MgO–5Al₂O₃ glasses were prepared by the conventional melt‐quenching method and their absorption and fluorescence spectra were characterized. Broadband near‐infrared (NIR) emission from Bi centers centered around 1240 nm with a full width at half maximum (FWHM) of 250 nm was observed, and the position of the emission peak strongly depends on the excitation wavelength. Increasing TeO₂ concentration results in the strong coloration of the glass, leading to the reduction and finally, complete quenching of the NIR emission. Based on Raman, X‐ray photoelectron spectroscopy and transmission microscopy observation, the coloration of the glass at high TeO₂ concentration can be ascribed to the precipitation of elemental Te nanoparticles of around 3–8 nm, which effectively suppresses the NIR emission by reabsorption. The precipitation of Te nanoparticles in an oxide glass may find novel applications in photonics and relevant fields.     

Pre-Analytical Considerations for Successful Next-Generation Sequencing (NGS): Challenges and Opportunities for Formalin-Fixed and Paraffin-Embedded Tumor Tissue (FFPE) Samples

In cancer drug discovery, it is important to investigate the genetic determinants of response or resistance to cancer therapy as well as factors that contribute to adverse events in the course of clinical trials. Despite the emergence of new technologies and the ability to measure more diverse analytes (e.g., circulating tumor cell (CTC), circulating tumor DNA (ctDNA), etc.), tumor tissue is still the most common and reliable source for biomarker investigation. Because of its worldwide use and ability to preserve samples for many decades at ambient temperature, formalin-fixed, paraffin-embedded tumor tissue (FFPE) is likely to be the preferred choice for tissue preservation in clinical practice for the foreseeable future. Multiple analyses are routinely performed on the same FFPE samples (such as Immunohistochemistry (IHC), in situ hybridization, RNAseq, DNAseq, TILseq, Methyl-Seq, etc.). Thus, specimen prioritization and optimization of the isolation of analytes is critical to ensure successful completion of each assay. FFPE is notorious for producing suboptimal DNA quality and low DNA yield. However, commercial vendors tend to request higher DNA sample mass than what is actually required for downstream assays, which restricts the breadth of biomarker work that can be performed. We evaluated multiple genomics service laboratories to assess the current state of NGS pre-analytical processing of FFPE. Significant differences in pre-analytical capabilities were observed. Key aspects are highlighted and recommendations are made to improve the current practice in translational research.     

脱铝超稳Y沸石负载Cu催化纤维素醇解合成乙酰丙酸乙酯

以非缓冲体系下柠檬酸脱铝改性的USY分子筛为载体,铜为金属活性组分,采用浸渍法制备脱铝超稳Y沸石负载Cu。考察了该催化剂对纤维素醇解制备乙酰丙酸乙酯（EL）的催化活性。在反应温度为200℃、反应时间为3 h的条件下,催化纤维素转化生成EL的产率为48.2%。通过XRD、FT-IR、BET、NH₃-TPD、Py-IR和TG-DTA对催化剂进行表征,结果表明,Cu-DUSY催化剂热稳定性好,晶体结构稳定。Cu-DUSY回收利用4次EL产率仍可保持40%以上,具有较好的催化活性。     

MDEA复配胺液脱除天然气中H2S性能

为了研究以N-甲基二乙醇胺（MDEA）为主体的MDEA+一乙醇胺（MEA）和MDEA+二乙烯三胺（DETA）两种配方混合胺液脱除H₂S性能,给工业中天然气脱硫配方提供参考和基础数据。利用小型反应釜进行吸收实验,使用单一MDEA胺液进行了工艺参数的筛选,同时考察吸收温度、吸收压力、再生温度对胺液脱除H₂S性能影响,得出升高吸收温度、吸收压力均可在一定程度内提升MDEA胺液的H₂S吸收效果,但当吸收温度过高时会降低胺液的H₂S吸收效果,吸收压力过高会造成脱硫成本的增加,筛选出最优吸收温度50℃,吸收压力5MPa,解吸油浴温度125℃。在优选出的实验工艺参数条件下进行不同添加剂对MDEA胺液脱除H₂S性能影响研究,考察不同配比的MDEA+DETA混合胺液和MDEA+MEA混合胺液脱除天然气中H₂S吸收及解吸性能。通过分析不同配比胺液的吸收负荷、吸收速率及解吸率等指标得出,MDEA单一胺液中添加二乙烯三胺（DETA）、一乙醇胺（MEA）胺液均可提升其H₂S吸收性能但并不利于胺液H₂S解吸性能的提升。性能较优配方为2.4mol/L MDEA+0.6mol/L MEA、2.4mol/L MDEA+0.6mol/L DETA混合胺液。