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81.
Xiao Ma Chongying Xu Zhibiao Mao Peiyu Ji Chenggang Jin Dongsheng Xu Yuqiang Ding 《应用有机金属化学》2020,34(2):e5349
A series of chemical vapor deposition (CVD) precursors have been synthesized by a single-step reaction of 1,1,3,3-tetramethylguanidine and a variety of silicon chlorides. The structures of the 1,1,3,3-tetramethylguanidinate-based compounds were verified by 1H NMR, 13C NMR, XPS, EI-MS, and elemental analysis. The thermal stability, transport behavior, and vapor pressures of these compounds were evaluated by simultaneous thermal analyses (STA). These compounds are highly stable and those in liquid form are very volatile. Silicon carbonitride (SiCN) thin films were prepared by using bis (tetramethylguanidine)-dimethyl-silane as the precursor in helicon wave plasma chemical vapor deposition (HWP-CVD). The properties of the films were investigated by SEM, AFM, and XPS. The results showed that the films have good uniformities, low friction coefficient, and high hardness, enabling the films for fabrication of semiconductor devices. 相似文献
82.
In this study, Pd based on 2-Aminopyrimidine and 1H-benzo[d]imidazol-2-amine functionalized Fe3O4 magnetic nanoparticles [(Pd-APM-PSi-Fe3O4) and (Pd-BIA-PSi-Fe3O4)] was designed and used for the synthesis of di aryl ether by Ulmann cross-coupling reactions. Ulmann reaction performed with mixing of the arylhalides and phenol derivatives in DMF solvent. The prepared catalysts were characterized with various analytical techniques such as FT-IR, XRD, TGA, SEM, TEM, EDX, ICP and VSM. Pd-APM-PSi-Fe3O4 and Pd-BIA-PSi-Fe3O4 catalysts demonstrated good to excellent yields catalytic efficiency for Ulmann reactions in comparison with to commercial palladium catalysts. The catalyst is easily recycled and reused without loss of the catalytic activity. The combined merits of reusable catalyst conditions make the condensation with safe operation, no leaching of pd into environment, low pollution, rapid access to products and simple workup. Also, these novel magnetic nanocatalysts are superior to the industry standard Pd in every relevant aspect. They feature a way higher initial activity, a much more convenient separation, better recycling, and less contamination of the products. Last but not least, they can be very easily prepared from commercially available Fe3O4 nanoparticles using standard laboratory equipment. 相似文献
83.
84.
Recent research has focused on increasing the evidentiary value of latent fingerprints through chemical analysis. Although researchers have optimized the use of organic and metal matrices for matrix‐assisted laser desorption/ionization‐mass spectrometry imaging (MALDI‐MSI) of latent fingerprints, the use of development powders as matrices has not been fully investigated. Carbon forensic powder (CFP), a common nonporous development technique, was shown to be an efficient one‐step matrix; however, a high‐resolution mass spectrometer was required in the low mass range due to carbon clusters. Titanium oxide (TiO2) is another commonly used development powder, especially for dark nonporous surfaces. Here, forensic TiO2 powder is utilized as a single‐step development and matrix technique for chemical imaging of latent fingerprints without the requirement of a high‐resolution mass spectrometer. All studied compounds were successfully detected when TiO2 was used as the matrix in positive mode, although, generally, the overall ion signals were lower than the previously studied CFP. TiO2 provided quality mass spectrometry (MS) images of endogenous and exogenous latent fingerprint compounds. The subsequent addition of traditional matrices on top of the TiO2 powder was ineffective for universal detection of latent fingerprint compounds. Forensic TiO2 development powder works as an efficient single‐step development and matrix technique for MALDI‐MSI analysis of latent fingerprints in positive mode and does not require a high‐resolution mass spectrometer for analysis. 相似文献
85.
Transport in Porous Media - The effective slip length at the interface between pure fluid flow and porous media composed of packed spheres has been accurately characterized. In this study, as the... 相似文献
86.
87.
Hang Xu Chun‐Shuai Cao Han‐Shi Hu Shi‐Bin Wang Jin‐Cheng Liu Peng Cheng Nikolas Kaltsoyannis Jun Li Bin Zhao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(18):6083-6088
Assembled from [Th48Ni6] nanocages, the first transition‐metal (TM)‐thorium metal–organic framework (MOF, 1 ) has been synthesized and structurally characterized. 1 exhibits high solvent and acid/base stability, and resistance to 400 kGy β irradiation. Notably, 1 captures ReO4? (an analogue of radioactive 99TcO4?, a key species in nuclear wastes) with a maximum capacity of 807 mg g?1, falling among the largest values known to date. Furthermore, 1 can enrich methylene blue (MB) and can also serve as an effective and recyclable catalyst for CO2 fixation with epoxides; there is no significant loss of catalytic activity after 10 cycles. Theoretical studies with nucleus‐independent chemical shifts and natural bond orbital analysis reveal that the [Th6O8] clusters in 1 have a unique stable electronic structure with (d–p)π aromaticity, partially rationalising 1 ′s stability. 相似文献
88.
Bijun Gao Jin Zhou Hongliang Wang Guping Zhang Jinghui He Qingfeng Xu Najun Li Dongyun Chen Hua Li Jianmei Lu 《中国化学》2019,37(2):148-154
Tetracycline (TC) and other antibiotics accumulated in groundwater and soil pollute ecological environment and threaten human health. Gold nanoparticles doped on photocatalysts are able to enhance the photodegradation efficiency during removing these antibiotics, but preparation of Au nanoparticles of well‐dispersion on photocatalysts remains challenging. In this work, zeolite imidazolate (ZIF‐8) was employed as the precursor to prepare Au@ZnO photocatalyst via impregnation and in‐situ reduction method to efficiently degrade the tetracycline in the aqueous solution. Au nanoparticles are of 10 nm in size and uniformly dispersed on the surfaces of ZnO microstructures. The as‐prepared Au@ZnO is able to remove 85.5% of TC of 0.010 mg/mL within 2 h, presenting higher photocatalytic activity than pure ZnO catalyst. Most importantly, the catalyst shows its superior stability after five cycles without structure and activity changing. The mechanism of the photocatalytic degradation was discussed in detail. 相似文献
89.
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
90.