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91.
The electrochemical behavior of austenitic stainless steel (Type 304) in 3 M sulfuric acid with 3.5% recrystallized sodium chloride at specific concentrations of butan-1-ol was investigated with the aid of potentiodynamic polarization, open circuit measurement and weight loss technique. Butan-1-ol effectively inhibited the steel corrosion with a maximum inhibition efficiency of 78.7% from weight-loss analysis and 80.9% from potentiodynamic polarization test at highest concentration studied. Adsorption of the compound obeyed the Freundlich isotherm. Thermodynamic calculations reveal physiochemical interactions and spontaneous adsorption mechanism. Surface characterizations showed the absence of corrosion products and topographic modifications of the steel. Statistical analysis depicts the overwhelming influence and statistical significance of inhibitor concentration on the inhibition performance. 相似文献
92.
Md Sabir Alam Md Noushad Javed Faheem Hyder Pottoo Aafrin Waziri Faisal A. Almalki Md Saquib Hasnain Arun Garg Md Khalid Saifullah 《应用有机金属化学》2019,33(9)
Microwave irradiation (MI) process characteristically enables extremely rapid “in‐core” heating of dipoles and ions, in comparison to conventional thermal (conductance) process of heat transfer. During the process of nanoparticles synthesis, MI both modulates functionality behaviors as well as dynamic of reaction in favorable direction. So, MI providing a facile, favorable and alternative approach during nanoparticles synthesis nanoparticles with enhanced catalytic performances. Although, conventionally used reducing and capping reagents of synthetic origin, are usually environmentally hazardous and toxic for living organism. But, in absence of suitable capping agent; stability, shelf life and catalytic activity of metallic nanoparticles adversely affected. However, polymeric templates which emerged as suitable choice of agent for both reducing and capping purposes; bearing additional advantages in terms of catalyst free one step green synthesis process with high degree of biosafety and efficiency. Another aspect of current works was to understand role of process variables in growth mechanism and catalytic performances of microwave processed metallic nanoparticles, as well as comparison of these parameters with conventional heating method. However, due to poor prediction ability with previously published architect OFAT (One factor at a time) design with these nanoparticles as well as random selection of process variables with their different levels, such comparison couldn't be possible. Hence, using gum Ghatti (Anogeissus latifolia) as a model bio‐template and under simulated reaction conditions; architect of QbD design systems were integrated in microwave processed nanoparticles to establish mechanistic role these variables. Furthermore, in comparison to conventional heating; we reported well validated mathematical modeling of process variables on characteristic of nanoparticles as well as synthesized gold nanoparticles of desired and identical dimensions, in both thermal and microwave‐based processes. Interestingly, despite of identical dimension, MI processed gold nanoparticles bearing higher efficiency (kinetic rate) against remediation of hazardous nitro dye (4‐nitrophenol), into safer amino (4‐aminophenol) analogues. 相似文献
93.
Denis D. Borisov Grigory R. Chermashentsev Roman A. Novikov Yury V. Tomilov 《Tetrahedron letters》2019,60(10):746-750
New “four-component” self-assembly of polyaromatic thiophene structures based on styrylmalonates and 5-phenylthiophene-2-carbaldehyde has been developed. This process is promoted by GaCl3 and involves two [2?+?3]-annulation steps on the CHO-groups and para-substitution into one Ph-ring. The main feature of discovered process is a high diastereoselectivity with a significant increase in molecular complexity. The resulting polyaromatic structures containing two thiophene moieties in each structure have intense color and strong absorption in a near UV spectral region with absorption maxima in the range of 257–360?nm. 相似文献
94.
95.
Dake Hu Tianqi Zhao Xiaofan Ping Husong Zheng Lei Xing Xiaozhi Liu Jingying Zheng Lifei Sun Lin Gu Chenggang Tao Dong Wang Liying Jiao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(21):7051-7055
Two‐dimensional (2D) PtSe2 shows the most prominent layer‐dependent electrical properties among various 2D materials and high catalytic activity for hydrogen evolution reaction (HER), and therefore, it is an ideal material for exploring the structure–activity correlations in 2D systems. Here, starting with the synthesis of single‐crystalline 2D PtSe2 with a controlled number of layers and probing the HER catalytic activity of individual flakes in micro electrochemical cells, we investigated the layer‐dependent HER catalytic activity of 2D PtSe2 from both theoretical and experimental perspectives. We clearly demonstrated how the number of layers affects the number of active sites, the electronic structures, and electrical properties of 2D PtSe2 flakes and thus alters their catalytic performance for HER. Our results also highlight the importance of efficient electron transfer in achieving optimum activity for ultrathin electrocatalysts. Our studies greatly enrich our understanding of the structure–activity correlations for 2D catalysts and provide new insight for the design and synthesis of ultrathin catalysts with high activity. 相似文献
96.
Durairaj Gopalakrishnan Santhanam Srinath Baburaj Baskar Nattamai S.P. Bhuvanesh Mani Ganeshpandian 《应用有机金属化学》2019,33(3)
Two organometallic Ru(II)‐p‐cymene complexes of the type [Ru(η6‐p‐cymene)(L)Cl]PF6 1 and 2 , where L is N,N‐bis(4‐isopropylbenzylidene)ethane‐1,2‐diamine (bien, L1 ) or N,N‐bis (pyren‐2‐ylmethylene)ethane‐1,2‐diamine (bpen, L2 ) have been prepared and characterized well. Because of appended pyrenyl groups in coordinated bpen ligand, the complex 2 exhibits higher DNA and protein binding than complex 1 in which isopropylbenzyl groups are incorporated. Interestingly, the luminescent characteristic complex 2 is unique in displaying DNA cleavage after light activation by UVA light at 365 nm through oxygen dependent mechanism. AFM analysis attests the photo‐induced DNA fragmentation ability of complex 2 . Also, the complex 2 cleaves the protein after light exposure in a non‐specific manner suggesting that it can act as a protein photo cleaving agent. In contrast to the trend of DNA and protein interaction of complexes, the complex 1 exhibits cytotoxic activity against human breast carcinoma ( MCF‐7 ) and liver carcinoma ( HepG2 ) with potency higher than that of complex 2 due to enhanced hydrophobicity of isopropyl groups present in p‐cymene and bien ligands. Indeed, complex 2 is inactive against MCF‐7 and HepG2 cancer cell lines even up to 200 μM concentration. The AO/EB staining assay reveals that the complex 1 is able to induce late apoptotic mode of cell death in breast cancer cells, which is further confirmed by inter‐nucleosomal DNA cleavage. Furthermore, the complexes 1 and 2 are evaluated for their catalytic activities and found to be working well for the β‐carboline directed C–H arylation to afford the desired products in good yield (40–47%). 相似文献
97.
Hydrogenation of acetophenone over nano‐Cu/SiO2 catalysts was investigated. The catalysts, prepared by a liquid precipitation method using various precipitating agents, were characterized using low‐temperature nitrogen adsorption, X‐ray diffraction, temperature‐programmed desorption of ammonia, hydrogen temperature‐programmed reduction, transmission electron microscopy and X‐ray photoelectron spectroscopy. It was found that the catalysts prepared by a homogeneous precipitation method had better activity and stability than those prepared by a co‐precipitation method. The catalyst prepared using urea as precipitating agent had well‐dispersed copper species, high surface area and abundant pore structure. The catalytic performance and mechanism of the Cu/SiO2 catalysts were further studied. It was found that the activity and stability of the catalysts could be improved by adjusting the proportion of Cu+/(Cu+ + Cu0). The sample prepared using urea as precipitating agent presented higher activity and selectivity. Also, the catalyst prepared using urea maintained a high catalytic performance while being continuously used for 150 h under the optimal reaction conditions. 相似文献
98.
Yeong‐Tarng Shieh Pei‐Yu Tai Chih‐Chia Cheng 《Journal of polymer science. Part A, Polymer chemistry》2019,57(21):2149-2156
Poly(methyl methacrylate) (PMMA) nanoparticles with a sensitive CO2‐responsive hydrophilic/hydrophobic surface that confers controlled dispersion and aggregation in water were prepared by emulsion polymerization at 50 °C under CO2 bubbling using amphiphilic diblock copolymers of 2‐dimethylaminoethyl methacrylate (DMAEMA) and N‐isopropyl acrylamide (NIPAAm) as an emulsifier. The amphiphilicity of the hydrophobic–hydrophilic diblock copolymer at 50 °C was triggered by CO2 bubbling in water and enabled the copolymer to serve as an emulsifier. The resulting PMMA nanoparticles were spherical, approximately 100 nm in diameter and exhibited sensitive CO2/N2‐responsive dispersion/aggregation in water. Using copolymers with a longer PNIPAAm block length as an emulsifier resulted in smaller particles. A higher concentration of copolymer emulsifier led to particles with a stickier surface. Given its simple preparation and reversible CO2‐triggered amphiphilic behavior, this newly developed block copolymer emulsifier offers a highly efficient route toward the fabrication of sensitive CO2‐stimuli responsive polymeric nanoparticle dispersions. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2149–2156 相似文献
99.
缪正武 《浙江大学学报(理学版)》2019,46(6):680-685
提出利用拉格朗日乘子法重新证明σ 2 ![]()
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算子的最优凹性,并定义了一个凸锥Γ 3 ? = λ = ( λ 1 , λ 2 , ? , λ n ) ∈ R n : σ 1 ( λ ) > 0 , σ 2 ( λ | i ) > 0 , 1 ≤ i ≤ n ![]()
![]()
。利用σ 2 ![]()
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算子的最优凹性,给出了σ 2 H e s s i a n 方 程 P o g o r e l o v ![]()
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型C 2 ![]()
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内估计,进而证明了σ 2 ( D 2 u ( x ) ) = 1 , x ∈ R n ![]()
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的满足二次多项式增长条件的Γ 3 ? - ![]()
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凸整解为二次多项式。 相似文献
100.
Reversible Activation of Water by an Air- and Moisture-Stable Frustrated Rhodium Nitrogen Lewis Pair
Dr. María Carmona Dr. Joaquina Ferrer Dr. Ricardo Rodríguez Dr. Vincenzo Passarelli Prof. Dr. Fernando J. Lahoz Dr. Pilar García-Orduña Dr. Laura Cañadillas-Delgado Prof. Dr. Daniel Carmona 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(60):13665-13670
[Cp*Rh(κ3N,N′,P- L )][SbF6] (Cp*=C5Me5), bearing a guanidine-derived phosphano ligand L , behaves as a “dormant” frustrated Lewis pair and activates H2 and H2O in a reversible manner. When D2O is employed, a facile H/D exchange at the Cp* ring takes place through sequential C(sp3)−H bond activation. 相似文献