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991.
Peng‐Fei Dai Xiao‐Shan Ning Hua Wang Xian‐Chao Cui Jie Liu Jian‐Ping Qu Yan‐Biao Kang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(16):5446-5449
Organic chemists now can construct carbon–carbon σ‐bonds selectively and sequentially, whereas methods for the selective cleavage of carbon–carbon σ‐bonds, especially for unreactive hydrocarbons, remain limited. Activation by ring strain, directing groups, or in the presence of a carbonyl or a cyano group is usually required. In this work, by using a sequential strategy site‐selective cleavage and borylation of C(aryl)?CH3 bonds has been developed under directing group free and transition metal free conditions. Methyl groups of various arenes are selectively cleaved and replaced by boryl groups. Mechanistic analysis suggests that it proceeds by a sequential intermolecular oxidation and coupling of a transient aryl radical, generated by radical decarboxylation, involving a pyridine‐stabilized persistent boryl radical. 相似文献
992.
Jingchao Li Dong Cui Jiaguo Huang Shasha He Zebin Yang Yan Zhang Yu Luo Kanyi Pu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(36):12810-12817
In this study, an organic semiconducting pro‐nanostimulant (OSPS) with a near‐infrared (NIR) photoactivatable immunotherapeutic action for synergetic cancer therapy is presented. OSPS comprises a semiconducting polymer nanoparticle (SPN) core and an immunostimulant conjugated through a singlet oxygen (1O2) cleavable linkers. Upon NIR laser irradiation, OSPS generates both heat and 1O2 to exert combinational phototherapy not only to ablate tumors but also to produce tumor‐associated antigens. More importantly, NIR irradiation triggers the cleavage of 1O2‐cleavable linkers, triggering the remote release of the immunostimulants from OSPS to modulate the immunosuppressive tumor microenvironment. Thus, the released tumor‐associated antigens in conjunction with activated immunostimulants induce a synergistic antitumor immune response after OSPS‐mediated phototherapy, resulting in the inhibited growth of both primary/distant tumors and lung metastasis in a mouse xenograft model, which is not observed for sole phototherapy. 相似文献
993.
994.
Hui Cheng Peixin Cui Fangrui Wang Liang‐Xin Ding Haihui Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(43):15687-15693
We demonstrate a simple and effective chemical equilibrium regulation strategy to improve the efficiency of electrochemical ammonia synthesis by constructing electrochemical reaction system that works at significantly lower pressure than the Haber–Bosch process. Transferring the nitrogen reduction reaction from ambient conditions to a lightly pressurized environment not only accelerates the activation of the N≡N triple bond but also inhibits the competing reaction of hydrogen evolution while promoting the dissolution and diffusion of nitrogen. The verification experiment of using well‐designed Fe3Mo3C/C composite nanosheets as the nitrogen reduction catalyst shows that the lower pressure reaction system can improve the Faradaic current efficiency by one order of magnitude. Moreover, the comparatively low‐pressure reaction system can greatly reduce the cell voltage of the ammonia synthesis reaction (up to 33 %) even at the relatively low pressure of 0.7 MPa, which is of significance for decreasing the energy consumption of electrochemical ammonia synthesis under mild conditions. 相似文献
995.
Xiaoli Wu Xulin Cui Wenjia Wu Jingtao Wang Yifan Li Zhongyi Jiang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(51):18695-18700
Lamellar membranes with well‐defined 2D nanochannels show fast, selective permeation, but the underlying molecular transport mechanism is unexplored. Now, regular robust MXene Ti3C2Tx lamellar membranes are prepared, and the size and wettability of nanochannels are manipulated by chemically grafted hydrophilic (?NH2) or hydrophobic (?C6H5, ?C12H25) groups. These nanochannels have a sharp difference in mass transfer behavior. Hydrophilic nanochannels, in which polar molecules form orderly aligned aggregates along channel walls, impart ultrahigh permeance (>3000 L m?2 h?1 bar?1), which is more than three times higher than that in hydrophobic nanochannels with disordered molecular configuration. In contrast, nonpolar molecules with disordered configuration in both hydrophilic and hydrophobic nanochannels have comparable permeance. Two phenomenological transport models correlate the permeance with the mass transport mechanism of molecules that display ordered and disordered configuration. 相似文献
996.
报导了采用基于室温脉冲量子级联激光器的脉内光谱检测技术,利用中心波长为1904 cm-1的量子级联激光器,在实验室对NO气体样品进行检测的研究结果. 针对单线直接吸收光谱反演算法进行了研究,介绍了基线拟合的最小二乘算法以获取其吸光度,根据HITRAN数据库中相应吸收谱线的吸收线强,采用扫描积分实现了气体浓度的反演,避免了标气标定造成的误差及污染;通过拟合残差分析得到了系统的检测限,达到34×10-6 m.
关键词:
量子级联激光器
中红外
多项式拟合
扫描积分 相似文献
997.
The development of a simple directly wearable approach for the rapid, specific and sensitive determination of biomarkers is of great importance to a variety of biomedical applications. Dental floss can provide a unique device platform for sensing of oral biomarkers. We show here for the first time the development of a smart dental floss for biosensing of glucose. The sensor was made by painting carbon graphite ink and Ag/AgCl ink on dental floss. Via the immobilization of glucose oxidase, we show the detection of glucose with a detection range of 0.048 mM to 19.5 mM and a response time of about 2 min. It is expected that our results could provide new exciting opportunities for the development of various flexible smart sensing devices in oral health applications. 相似文献
998.
Xiaodong Jin Suping Cui Shibing Sun Yingliang Tian Feng Lv Xiaoyu Gu Hongfei Li Jun Sun Sheng Zhang Serge Bourbigot 《先进技术聚合物》2019,30(7):1605-1615
In this work, a novel sulfur‐based flame retardant (SA‐M) was synthesized by the self‐assembly of melamine and sulfamic acid. The chemical structure of SA‐M was fully characterized. SA‐M, in company with Al2O3, was then introduced into polyamide 11 (PA 11) by melt compounding in order to improve the fire resistance of the polymer substrate. The observation by scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) indicated the well dispersion of SA‐M in PA 11 matrix. The fire performance of PA 11 composites was evaluated by limiting oxygen index (LOI), vertical burning (UL‐94), and cone calorimeter tests, respectively. The results showed that the presence of 17.5% SA‐M and 2.5% Al2O3 increased the LOI value from 22.4% to 30.9%, upgraded the UL‐94 rating from no rating to V‐0, significantly eliminated the melt dripping, and decreased the peak heat release rate from 1024 to 603 kW/m2. The thermal behaviors were investigated by thermogravimeric analysis (TGA) and TGA‐Fourier transform infrared spectroscopy (FTIR). It was suggested that SA‐M took effects mainly in gas phase by diluting the combustible fuel, leading to the improvement of the fire resistance of PA 11. 相似文献
999.
Russian Journal of Coordination Chemistry - Two new cis-dioxomolybdenum(VI) complexes, [MoO2(L1)MeOH] (I) and [MoO2(L2)MeOH] (II) with potentially tridentate ONO aroylhydrazone Schiff bases derived... 相似文献
1000.
Based on an official standard method of lutein analysis, an improved high performance liquid chromatography (HPLC) method for simultaneously detecting lutein and zeaxanthin was developed as focusing on the sample preparation protocol. The optimal pretreatment conditions included a saponification in a water bath for 15?min at a constant temperature of 50?°C, using a 10?mL 60% (w/v) potassium hydroxide solution, followed by extraction using 100?mL mixture of n-hexane, ethyl ether and cyclohexane (40: 40: 20, v/v/v). A mixture of dichloromethane, acetonitrile and methanol (20: 30: 50, v/v/v) was validated to elute lutein and zeaxanthin on a C30 column (4.6?×?250?mm, 5?µm). The resolution between lutein and zeaxanthin is ≥2.5. A millet sample was used for methodological verification and the results showed that the linear relations for lutein and zeaxanthin were good in ranges of 0.23–9.37?μg/mL and 0.30–12.02?μg/mL, respectively. The relative standard deviations of lutein and zeaxanthin were 1.40% and 5.09%, respectively, and their spiked recoveries were between 86.60% and 98.75%. The lutein and zeaxanthin results from this modified HPLC method are superior to those from the Chinese official method and ultrasonic extraction method. 相似文献