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891.
Meccanica - A flow mixing nozzle can produce satisfactory atomization for heavy oil. However, the study of the internal flow pattern of this nozzle, along with the spray morphology and its... 相似文献
892.
YANG Liming GUO Lixin YU Hao WANG Guan SUN Jiangman ZHANG Pengfei GU Xinggui TANG Ben Zhong 《高等学校化学研究》2021,37(1):129-136
The development of fluorescent nanocrystals based on organic small molecules is of great importance in bioimaging due to the merits of easy modification,high brightness and excellent photostability,however suffering from the emission-detrimental aggregation-caused quenching(ACQ)effect.Herein,we successfully designed and synthesized an AIE-active di(N,N-dimethylaniline)-dibenzofulvene(named as NFTPE),which exhibits the crystallization-induced emission enhancement(CIEE)effect.Interestingly,two types of yellow-and orange-emissive crystals for NFTPE were obtained,exhibiting aggregation microenvironment-dependent emission tuning in the solid state.Single-crystal analysis and density functional theory(DFT)calculations reveal that different aggregation microenvironments result in the distinct molecular conformation for various emission.Excitingly,the crystallization of NFTPE in an aqueous solution under the assistance of amphiphilic PEG polymer matrices could be monitored in situ by the fluorescence changes,facilitating the preparation of NFTPE nanocrystals(NFTPE-NCs)by adjusting the aggregation microenvironment.The obtained NFTPE-NCs exhibit the superior performance in cell imaging in respect to high brightness,photostability,and biocompatibility,thus demonstrating the potential in bioimaging applications. 相似文献
893.
Chao-Shen Zhang Bei-Bei Zhang Liang Zhong Xiang-Yu Chen Zhi-Xiang Wang 《Chemical science》2022,13(13):3728
A DFT study has been conducted to understand the asymmetric alkyl–alkyl bond formation through nickel-catalysed reductive coupling of racemic alkyl bromide with olefin in the presence of hydrosilane and K3PO4. The key findings of the study include: (i) under the reductive experimental conditions, the Ni(ii) precursor is easily activated/reduced to Ni(0) species which can serve as an active species to start a Ni(0)/Ni(ii) catalytic cycle. (ii) Alternatively, the reaction may proceed via a Ni(i)/Ni(ii)/Ni(iii) catalytic cycle starting with a Ni(i) species such as Ni(i)–Br. The generation of a Ni(i) active species via comproportionation of Ni(ii) and Ni(0) species is highly unlikely, because the necessary Ni(0) species is strongly stabilized by olefin. Alternatively, a cage effect enabled generation of a Ni(i) active catalyst from the Ni(ii) species involved in the Ni(0)/Ni(ii) cycle was proposed to be a viable mechanism. (iii) In both catalytic cycles, K3PO4 greatly facilitates the hydrosilane hydride transfer for reducing olefin to an alkyl coupling partner. The reduction proceeds by converting a Ni–Br bond to a Ni–H bond via hydrosilane hydride transfer to a Ni–alkyl bond via olefin insertion. On the basis of two catalytic cycles, the origins for enantioconvergence and enantioselectivity control were discussed.The enantioconvergent alkyl–alkyl coupling involves two competitive catalytic cycles with nickel(0) and nickel(i) active catalysts, respectively. K3PO4 plays a crucial role to enable the hydride transfer from hydrosilane to nickel–bromine species. 相似文献
894.
895.
SHEN Qifei XU Ruohan WANG Zhi ZHAO Tianyu ZHOU Yu XU Yanzi YANG Zhiwei LEI Ming MENG Lingjie DANG Dongfeng 《高等学校化学研究》2021,37(1):143-149
Aggregation-induced emission(AIE)luminogens(AIEgens)with high brightness in aggregates exhibit great potentials in biological imaging,but these AIEgens are seldom applied in super-resolution biological imaging,especially in the imaging by using the structural illumination microscope(SIM).Based on this consideration,we synthesized the donor-acceptor typed AIEgen of DTPA-BTN,which not only owns high brightness in the near-infrared(NIR)emission region from 600 nm to 1000 nm(photoluminescence quantum yield,PLQYs=11.35%),but also displays excellent photo-stability.In addition,AIE nanoparticles based on 4,7-ditriphenylamine-[1,2,5]-thiadiazolo[3,4-c]pyridine(DTPA-BTN)were also prepared with highly emissive features and excellent biocompatibility.Finally,the developed DTPA-BTN-based AIE nanoparticles were applied in the super-resolution cellular imaging via SIM,where much smaller full width at half-maximum values and high signal to noise ratios were obtained,indicating the superior imaging resolution.The results here imply that highly emissive AIEgens or AIE nanoparticles can be promising imaging agents for super-resolution imaging via SIM. 相似文献
896.
聚酰亚胺/SiO2杂化膜的制备、表征和气体渗透性能 总被引:1,自引:0,他引:1
采用溶胶凝胶法,在以TiO2为过渡层的硅藻土-莫来石陶瓷膜管基底上,制备了组分不同的聚酰亚胺/SiO2杂化膜。聚酰亚胺是利用4,4′-六氟亚异丙基邻苯二甲酸酐、2,4,6-三甲基-1,3-苯二胺和3,5-二氨基苯甲酸在溶液中进行亚胺化完成的。采用FT-IR、TG/DTA、DSC、SEM、BET和气体渗透测定对膜进行了表征和测试。结果表明,聚酰亚胺通过支链上的羧酸基和SiO2相键连织构成了具有规则孔道的空间网状结构,并且随着SiO2含量的增加孔径逐渐减小;杂化膜具有较高的热稳定性和有机无机兼容性;相对于聚酰亚胺膜,杂化膜对H2、CO2和H2O与N2相比较具有较高的分离性,SiO2含量为25(wt)%的杂化膜对H2/N2、CO2/N2和H2O/N2的分离因子分别达到55.9、31.1和42.8。 相似文献
897.
898.
ML/Y分子筛复合材料的制备,表征及其催化性能研究 总被引:2,自引:2,他引:0
采用沸石合成法制备了ML/Y(M= Fe,Co,Cr;L= 8- quinolinoland salicylic acid (denoted asQx and SArespectively)) 复合材料,并通过XRD、FTIR、ICP、UV- vis 及催化反应等手段对其进行了表征。FTIR和UV- vis 测试结果表明: 合成体系中含有的金属配合物经过水热晶化后封装或固定在分子筛的空腔中。通过X射线衍射原位跟踪Y型分子筛的晶化过程,发现合成体系中含有金属配合物的性质及其量的多少不仅对Y型分子筛的晶化有很大影响,而且使其封装或固定在分子筛中的量也有所差异。另外,以环己烷氧化为探针反应考察了ML/Y的催化性能,结果表明ML/Y的氧化能力来自于所封装或固定的金属配合物,其氧化能力主要取决于配合物中心离子的性质 相似文献
899.
900.
Inside Back Cover: Plasmon‐Assisted Water Splitting Using Two Sides of the Same SrTiO3 Single‐Crystal Substrate: Conversion of Visible Light to Chemical Energy (Angew. Chem. Int. Ed. 39/2014)
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