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931.
在没有溶剂介质参与的高分子聚合反应中,高分子凝聚态的变化与化学反应之间的作用关系变得更加直接。以熔融聚合、反应挤出、固相聚合为代表的高分子树脂无溶剂生产技术是集高分子树脂合成、材料加工制备及工程一体化的新兴科学与技术,是当代材料科学领域发展的前沿领域,代表着高分子树脂生产技术发展的必然趋势。本文将上述这三种典型的树脂工业合成技术及相应机理进行了简要的介绍,并分别以聚对苯二甲酸乙二醇酯(PET)和聚乳酸(PLA)的实际生产研究情况为例,展示三种生产技术之间的相互联系,揭示这三种无溶剂型高分子制备技术过程中出现的高分子凝聚态变化与化学反应之间的基本问题,为广大科研工作提供一些有价值的参考。 相似文献
932.
Yao Kun Liu Zheng Li Hang Xu Dan Zheng Wen-Hua Quan Yi-Wu Cheng Yi-Xiang 《中国科学:化学(英文版)》2022,65(10):1945-1952
Science China Chemistry - We report the rational design of a dual stimulus-activated quaternary chiral emission nematic liquid crystals (Q-N*-LCs) containing light-driven chiral dopant R-S-R-1, a... 相似文献
933.
Vacuum Ultraviolet Free-Electron Laser Photoionization Mass Spectrometry of Alpha-pinene Ozonolysis 下载免费PDF全文
Xiangyu Zang Zhaoyan Zhang Chong Wang Tiantong Wang Huijun Zheng Hua Xie Jiayue Yang Dongxu Dai Guorong Wu Weiqing Zhang Gang Li Xueming Yang Ling Jiang 《化学物理学报(中文版)》2022,35(2):281-288
934.
The photoactivity of CdS nanorods was greatly improved by amino functionalized accordion-like MXene and spherical ZnSnO3. MXene possesses good electron transfer capability and ZnSnO3 presents matched energy band with CdS, which deeply accelerate the electron transfer and prevent the recombination of photogenerated electron-hole pair, leading to a strong photoelectrochemical (PEC) response. Taking the merit of the improved photoactivity of CdS nanorods, a novel PEC biosensor was constructed for DNA hydromethylation detection based on immune recognition of target molecule, where 5-hydroxymethyl-2′-deoxycytidine triphosphate (5hmdCTP) was employed as detect target, CdS/MXene was used as photoactive material, and ZnSnO3 was adopted as signal amplification unit. Under enzymatic covalent reaction of –CH2OH of 5hmdCTP with –NH2 of MXene, 5hmdCTP was specifically recognized and captured. Then, taking advantages of the covalent reaction between phosphate group of 5hmdCTP and ZnSnO3, the signal amplification unit was captured. Under the optimum conditions, this PEC biosensor presents wide linear range of 0.008–100 nM and low detection limit of 4.21 pM (3σ). The applicability of the developed method was evaluated by investigating the effect of Cd2+ and perfluorohexane compound pollutant on 5-hydroxymethylcytosine content in the genomic DNA of the roots and leaves of wheat seedlings. 相似文献
935.
Y. Li L. Wu Q. Wang Q. Zhou C.Y. Cao S. Zheng Z. Zhou H.M. Wong Q.L. Li 《Materials Today Chemistry》2022
The aging of the global population has caused dentin exposure and root caries to become significant patient-management issues in clinical dentistry. Biomimetic remineralization, as a non-invasive therapeutic method, is of great significance to solve the problem. Herein, a novel biomimetic-mineralizing strategy to induce the self-healing of dentin defects with similar tooth structure was developed through the easy one-step polydopamine (PDA)-assisted co-deposition of polyacrylic acid (PAA) (denoted as PDA@PAA) in vitro. Immersing demineralized dentin into PAA and dopamine (DA) mixed solutions. Hereafter, the modified demineralized dentin was immersed in the supersaturated solution of calcium and phosphate at 37 °C at designated time. Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and attenuated total reflection fourier transform infrared (ATR-FTIR) were performed to analyze the interaction and co-deposition between PDA and PAA. The remineralization of demineralized dentin was characterized by field emission scanning electron microscope (FE-SEM), TEM, X-ray diffraction (XRD), friction and wear test, nanoindentation, acid resistance. And the cytocompatibility of PDA@PAA was evaluated by cell counting kit-8 (CCK-8) and cell morphology observation. The results that PAA inhibited further PDA polymerization and aggregation, PDA@PAA were co-deposited onto the surface of demineralized dentin matrix. SEM and TEM showed that the demineralized-dentin modified with PDA@PAA was completely remineralized at 12 h, not only the dentin tubules were occluded, but more importantly, the demineralized dentin collagen matrix was remineralized. Moreover, after mineralization for 24 h, a dense mineral layer similar to enamel structure was regenerated on the surface of dentin and closely combined with dentin. The results of mechanical properties and acid resistance suggested that the mechanical properties of the regenerated enamel-like structure are close to that of enamel, and its acid resistance is better than that of enamel. This study demonstrated that the PDA-assisted co-deposition of PAA can offer an inexpensive, rapid, and efficient strategy for the management of illnesses related to exposed and demineralized dentin. 相似文献
936.
Wenbo Liu Dr. Peichen Tang Yi Zheng Dr. Yun-Lai Ren Xinzhe Tian Wankai An Prof. Xianfu Zheng Yinggang Guo Zhenpeng Shen 《化学:亚洲杂志》2021,16(21):3509-3513
Nitrogen transfer from cyanide anion to an aldehyde is emerging as a promising method for the synthesis of aromatic nitriles. However, this method still suffers from a disadvantage that a use of stoichiometric Cu(II) or Cu(I) salts is required to enable the reaction. As we report herein, we overcame this drawback and developed a catalytic method for nitrogen transfer from cyanide anion to an alcohol via the complete cleavage of the C≡N triple bond using phen/Cu2O as the catalyst. The present condition allowed a series of benzyl alcohols to be smoothly converted into aromatic nitriles in moderate to high yields. In addition, the present method could be extended to the conversion of cinnamic alcohol to 3-phenylacrylonitrile. 相似文献
937.
Huijun Wang Jie Gao Dr. Xiang Xu Dr. Baogen Liu Lingyun Yu Yadong Ren Dr. Rui Shi Prof. Zheng Zeng Prof. Liqing Li 《化学:亚洲杂志》2021,16(9):1118-1129
To investigate the effects of oxygen-containing functional groups on the adsorption of volatile organic compounds (VOCs) with different polarity, oxygen-rich porous carbon materials (OPCs) were synthesized by heat treatment of glucose/potassium oxalate material. The carbon material had a large specific surface area (1697 m2 g−1) and a high oxygen content (18.95 at.%). OPC exhibited high adsorption capacity of toluene (309 mg g−1) and methanol (447 mg g−1). The specific surface area and total pore volume determined the adsorption capacity of toluene and methanol at the high-pressure range, while the oxygen-containing groups became the main factor affecting the methanol adsorption at the low-pressure range due to the hydrogen bond interaction through the density functional theory (DFT) calculations. This study provides an important hint for developing a novel O-doped adsorbent for the VOCs adsorption applications and analyzing the role of oxygen-containing groups in the VOCs adsorption under the low-pressure range. 相似文献
938.
Fangxiao Wang Jianhai Ren Zihao Zheng Qiye Liu Dr. Chun-yang Zhang 《ChemistryOpen》2021,10(7):713-719
Fuel cells have attracted increasing attention due to their low cost, high energy density, low environmental pollution, and abundant raw materials. Oxygen reduction reaction (ORR) is a core technology of fuel cells, and the development of new electrocatalysts with high ORR performance is highly desirable. Herein, we synthesize a series of B, N co-doped hierarchical porous carbons using a soft template method with the integration of self-assembly, calcination and etching. The obtained materials exhibit hierarchical porous structures, controllable pore distribution, partial graphite structures, and B, N co-doping. They can function as the cost-effective and metal-free electrocatalysts, facilitating the diffusion of electrolyte ions and the improvement of ORR performance. Especially, the B, N co-doped porous carbon with the B-to-N molar ratio of 5 (BNC-5) displays a high ORR activity with a half-wave potential (E1/2) of 0.73 V, an onset potential (Eonset) of 0.94 V, and a high limiting current density (JL) of 5.98 mA cm−2, superior to the N-doped C (NC) and BNC-1 (the B-to-N molar ratio=1), BNC-3 (the B-to-N molar ratio=3) and BNC-7 (the B-to-N molar ratio=7) under the identical conditions. Moreover, the BNC-5 exhibits good cycling stability after 5000 cyclic voltammetry (CV) cycles and excellent tolerance toward even 3 M methanol. This research provides a new approach for the facile synthesis of dual element-doped carbon electrocatalysts with high ORR performance. 相似文献
939.
Yan-Zheng Zhang Juan-Juan Si Shan-Shan Li Guo-Zhi Zhang Shuai Wang Huo-Qing Zheng Fu-Liang Hu 《Molecules (Basel, Switzerland)》2021,26(9)
Honey has good antimicrobial properties and can be used for medical treatment. The antimicrobial properties of unifloral honey varieties are different. In this study, we evaluated the antimicrobial and antioxidant activities of nine kinds of Chinese monofloral honeys. In addition, headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) technology was used to detect their volatile components. The relevant results are as follows: 1. The agar diffusion test showed that the diameter of inhibition zone against Staphylococcus aureus of Fennel honey (21.50 ± 0.41 mm), Agastache honey (20.74 ± 0.37 mm), and Pomegranate honey (18.16 ± 0.11 mm) was larger than that of Manuka 12+ honey (14.27 ± 0.10 mm) and Manuka 20+ honey (16.52 ± 0.12 mm). The antimicrobial activity of Chinese honey depends on hydrogen peroxide. 2. The total antioxidant capacity of Fennel honey, Agastache honey, and Pomegranate honey was higher than that of other Chinese honeys. There was a significant positive correlation between the total antioxidant capacity and the total phenol content of Chinese honey (r = 0.958). The correlation coefficient between the chroma value of Chinese honey and the total antioxidant and the diameter of inhibition zone was 0.940 and 0.746, respectively. The analyzed dark honeys had better antimicrobial and antioxidant activities. 3. There were significant differences in volatile components among Fennel honey, Agastache honey, Pomegranate honey, and Manuka honey. Hexanal-D and Heptanol were the characteristic components of Fennel honey and Pomegranate honey, respectively. Ethyl 2-methylbutyrate and 3-methylpentanoic acids were the unique compounds of Agastache honey. The flavor fingerprints of the honey samples from different plants can be successfully built using HS-GC-IMS and principal component analysis (PCA) based on their volatile compounds. Fennel honey, Agastache honey, and Pomegranate honey are Chinese honey varieties with excellent antimicrobial properties, and have the potential to be developed into medical grade honey. 相似文献
940.
Xifeng Hou Yanhui Zheng Xiaolong Ma Yuheng Liu Zichuan Ma 《Molecules (Basel, Switzerland)》2021,26(4)
To expand the applications of graphene-based materials to biogas purification, a series of reduced graphene oxide aerogels (rGOAs) were prepared from industrial grade graphene oxide using a simple hydrothermal method. The influences of the hydrothermal preparation temperature on the textural properties, hydrophobicity and physisorption behavior of the rGOAs were investigated using a range of physical and spectroscopic techniques. The results showed that the rGOAs had a macro-porous three-dimensional network structure. Raising the hydrothermal treatment temperature reduced the number of oxygen-containing groups, whereas the specific surface area (SBET), micropore volume (Vmicro) and water contact angle values of the rGOAs all increased. The dynamic adsorption properties of the rGOAs towards hexamethyldisiloxane (L2) increased with increasing hydrothermal treatment temperature and the breakthrough adsorption capacity showed a significant linear association with SBET, Vmicro and contact angle. There was a significant negative association between the breakthrough time and inlet concentration of L2, and the relationship could be reliably predicted with a simple empirical formula. L2 adsorption also increased with decreasing bed temperature. Saturated rGOAs were readily regenerated by a brief heat-treatment at 100 °C. This study has demonstrated the potential of novel rGOA for applications using adsorbents to remove siloxanes from biogas. 相似文献