Waveguide external cavity narrow linewidth semiconductor lasers

Narrow linewidth light source is a prerequisite for high-performance coherent optical communication and sensing.Waveguide-based external cavity narrow linewidth semiconductor lasers(WEC-NLSLs)have become a competitive and attractive candidate for many coherent applications due to their small size,volume,low energy consumption,low cost and the ability to integrate with other optical components.In this paper,we present an overview of WEC-NLSLs from their required technologies to the state-of-the-art progress.Moreover,we highlight the common problems occurring to current WEC-NLSLs and show the possible approaches to resolving the issues.Finally,we present the possible development directions for the next phase and hope this review will be beneficial to the advancements of WEC-NLSLs.     

Influence of thermal runaway in styrene–acrylonitrile bulk copolymerization revealed by computational fluid dynamics modeling

The computational fluid dynamics (CFD) and kinetic-based moment methods coupled approach is adopted to simulate the bulk copolymerization of styrene–acrylonitrile (SAN) in a stirred tank reactor. Numerical simulations are carried out to investigate the impacts of impeller speed, monomer ratio, initiator ratio, and initial reaction temperature on the copolymerization process and product properties. Particularly, the Chaos theory is selected as a criterion for evaluating the occurrence of the thermal runaway. The Flory's and Stockmayer's distributions are employed to calculate chain length distribution and copolymer composition distribution of copolymer. The simulation results highlight that the appearance of thermal runaway can be postponed by properly increasing the rotation speed, decreasing the initiator loadings, initial acrylonitrile contents and initial reactor temperature. Furthermore, significant differences exist in the product properties that predicted by the ideal and non-ideal models, which demonstrates that the temperature heterogeneity plays a crucial role in SAN copolymerization. This study could offer references for the safe operation and design of polymerization processes.     

Effect of comb-type copolymer on crystallization of paraffin from waxy oils and methyl ethyl ketone (MEK) -toluene dewaxing

In this research, maleic anhydride-α-octadecene copolymer and its derivative with phenylethylamine was synthesized and its effect on the crystallization of paraffins was investigated. This derivative, when added into second cut of vacuum gas oil and forth cut of vacuum gas oil, increases the size and improves aggregation of paraffin crystals observed by polarizing light microscopy, increases onset temperature and enthalpy of paraffin crystallization determined by differential scanning calorimetry, improves the dewaxing efficiency with dosage of 100?ppm explored by MEK-toluene dewaxing.     

Poly(L-lysine)-poly(ethylene glycol) layers with different structure and their influence on silica suspension stability

The effects of the structure of di- and triblock copolymers of poly(L-lysine) – LYS with poly(ethylene glycol) – PEG as well as the length of nonionic fragment in the LYS-PEG macromolecule on the copolymer chains conformation in the adsorption layer formed on the colloidal silica (SiO2) surface were examined. Spectrophotometry and turbidimetry were applied for the determination of copolymer adsorbed amounts and stability coefficients of silica aqueous suspensions. The electrokinetic parameters such as solid surface charge density and zeta potential were also estimated. The adsorption of LYS-PEG was proved to be the highest at pH 10 whereas the lowest adsorption on the solid surface was found for the triblock copolymer with long fragments of LYS at the same pH value.     

催化裂化柴油加氢转化馏分利用方案研究

中国石化大连(抚顺)石油化工研究院开发了以催化裂化柴油为原料生产高辛烷值汽油调合组分新工艺技术（FD2G技术）。针对催化裂化柴油加氢改质产品，通过分析其组分的烃类组成，分别加工利用，对于改善产品结构和提高市场竞争力十分有益。研究结果表明：加工高芳烃催化裂化柴油时，汽油产品芳烃含量高，辛烷值高，其中C6~C8芳烃富集的窄馏分可以作为芳烃抽提装置原料生产化工产品；加工低芳烃含量的催化裂化柴油时，汽油产品中芳烃含量低，辛烷值偏低，可将富集大量环烷烃的窄馏分作为重整装置原料，富含芳烃的窄馏分作为高辛烷值汽油调合组分。     

涤纶针织布的有机硅改性聚酯-聚醚共聚物整理

采用酯交换-缩聚反应,在催化剂与稳定剂的作用下,以对苯二甲酸二甲酯、乙二醇、聚乙二醇与自制聚醚硅油为原料合成了有机硅聚酯-聚醚共聚物整理剂。试验探究了聚醚硅油的用量对反应产物性能的影响,通过红外光谱表征了有机硅聚酯-聚醚共聚物的结构,并对其在涤纶针织物上的最佳应用条件进行了研究。结果表明:聚醚硅油用量占酯交换反应物质量分数为6%时,用其处理的针织物亲水性和手感较好;最佳使用工艺条件为浸轧法,质量浓度20 g/L,120℃焙烘60s。     

Constraint effect caused by graphene on in situ grown Gr@WO3 -nanobrick hybrid material

This work reported the abnormal constraint effect of graphene on the structural and optical properties of in situ grown Gr@WO₃ nanobrick (NB) hybrid nanomaterials. Stable hybrid Gr@WO₃ nanomaterials were synthesized through a one-step hydrothermal method, in which different graphene contents (0.1, 0.3 and 0.5 wt%) were directly introduced into the precursor solution of tungsten oxide. The existence of graphene in the nucleation phase of tungsten oxide NB decreased the crystallite size from 49.5 nm to 45.3 nm, increased the microstrain from 1.10% to 1.44% and the optical bandgap of the hybrid samples from 2.68 eV to 2.78 eV, and reduced the radiative recombination efficiency of tungsten oxide NB. The hybridization between graphene and tungsten oxide NBs was confirmed by X-ray diffraction and Raman scattering analysis. The optical properties of materials were studied based on the absorbance and diffuse reflectance spectra. In this work, we also proposed a reliable method to estimate the optical bandgap of the sample from the diffuse reflectance spectrum. These findings would introduce an alternative method of fabrication and enhance the understanding of in situ hybrid materials.     

偶联剂对PLA/PBAT/WF复合材料3D打印性能的影响

以聚乳酸（PLA）和聚己二酸/对苯二甲酸丁二酯（PBAT）为基体，杨木粉（WF）为填充增强材料，使用混炼机熔融共混制备PLA/PBAT/WF复合材料，采用熔融沉积成型（FDM）技术制备标准实验试样，通过扫描电子显微镜、红外光谱分析、旋转流变测试以及力学试验等方法，研究不同含量的硅烷偶联剂KH550对PLA/PBAT共混物以及PLA/PBAT/WF的相容性、流变性及力学性能的影响。结果表明，在偶联剂用量为3 %（质量分数，下同）时，拉伸强度提高了136 %；偶联剂KH550与 PLA和PBAT共价键偶联生成接枝聚合物，二者相容性得到提高；同时偶联剂与WF表面羟基发生缩聚反应有效的改善了其与PLA/PBAT的基体相容性，PLA/PBAT/WF复合材料的FDM的制件力学性能得到较大提升；复合材料的黏度随偶联剂含量的增加呈下降的趋势，含量为3 %时线材的综合打印性能及制品质量最佳。     

Halogenation effect promoted low bandgap polymers based on asymmetric isoindigo unit with low energy loss

To optimize the energy levels of the structural framework of isoindigo polymers, a series of asymmetric isoindigo based low bandgap polymers with chlorine, fluorine and thiazole substituents was constructed and their optical, electrochemical and photovoltaic properties were comparatively evaluated for the impact of different substitutions. In comparison with the polymer based on 2,2'‐bithiophene and isoindigo unit (PTi) with non‐substituted bithiophene as the donor moiety, the highest occupied molecular orbital energy level for the newly synthesized polymers is significantly decreased, and in turn an improvement of the open‐circuit voltage (V_OC) is noted in the corresponding photovoltaic devices. More importantly, combined with a low bandgap of 1.32 eV, the energy losses (E_loss) could be reduced to 0.61 eV for polymer based on chlorinated 2,2'‐bithiophene and isoindigo unit (PCl). In addition, the halogen moieties are observed to be superior in device fabrication and give better values than the thiazole substituent. Both fluorinated and chlorinated polymer donors exhibited improved performance compared with the original polymer PTi. Consequently, this work not only presents the influence of different electron withdrawing substituents on the physicochemical and photovoltaic performance, but also backs the concept of how to reduce the energy loss via the heteroatom effect. © 2020 Society of Chemical Industry     

MAPP/EAA处理对聚丙烯/小麦秸秆粉复合材料性能的影响

研究了马来酸酐接枝聚丙烯（MAPP）、乙烯丙烯酸共聚物（EAA）处理对聚丙烯（PP） /小麦秸秆粉（WSP）复合材料性能的影响。结果表明，随着体系中MAPP质量份数的增加，PP/WSP的拉伸强度和弯曲强度均逐渐增大，但冲击强度却先增加后减小，复合材料达到塑化峰的时间逐渐延长；使用EAA后，无论体系中是否已经使用了MAPP，PP/WSP的拉伸、弯曲和冲击强度均可得以提高，特别对于未使用MAPP的体系，效果更加明显，可分别提高65.04 %、45.42 %和6.75 %，储能模量增加，表面疏水性增强，平衡扭矩从13.9 N·m降至11.8 N·m，吸水尺寸变化率及吸水率下降，吸水平衡时间缩短；使用EAA可改善PP/WSP中WSP与PP间的界面结合，改善PP/WSP力学性能、热稳定性能、表面疏水性能、尺寸稳定性能和加工性能，降低其吸水率。