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排序方式: 共有419条查询结果,搜索用时 265 毫秒
411.
Sonochemical synthesis, size controlling and gas sensing properties of NiO nanoparticles 总被引:1,自引:0,他引:1
Nanoparticles of NiO (NP-NiO) were prepared by a novel sonochemical route from Ni acetate and sodium hydroxide without any requirement of calcinations steps at high temperature and without surfactants. Drop casting of the nanocrystals onto alumina substrates allowed the fabrication of gas sensing devices, which were tested towards NO2 and CO and showed promising results. At low working temperature, the NiO nanoparticles based sensors are selective to nitrogen oxide; in fact a good sensitivity is shown at 200 °C at low concentration (2 ppm), while at temperature above 350 °C, high responses are obtained for carbon monoxide. The results obtained are stimulating for further developing of NP-NiO based sensor devices. 相似文献
412.
Effect of fluids properties on non-equilibrium capillarity effects: Dynamic pore-network modeling 总被引:1,自引:0,他引:1
We have developed a Dynamic Pore-network model for Simulating Two-phase flow in porous media (DYPOSIT). The model is applicable to both drainage and imbibition processes. Employing improved numerical and geometrical features in the model facilitate a physically-based pore-scale simulator. This computational tool is employed to perform several numerical experiments (primary and main drainage, main imbibition) to investigate the current capillarity theory. Traditional two-phase flow formulations state that the pressure difference between the two phase is equal to the capillary pressure, which is assumed to be a function of saturation only. Many theoretical and experimental studies have shown that this assumption is invalid and the pressure difference between the two fluids is not only equal to the capillary pressure but is also related to the variation of saturation with time in the domain; this is referred to as the non-equilibrium capillarity effect. To date, non-equilibrium capillarity effect has been investigated mainly under drainage. In this study, we analyze the non-equilibrium capillarity theory under drainage and imbibition as a function of saturation, viscosity ratio, and effective viscosity. Other aspects of the dynamics of two-phase flow such as trapping and saturation profile are also studied. 相似文献
413.
Saheb V 《The journal of physical chemistry. A》2011,115(17):4263-4269
The triplet potential energy surface of the O((3)P) + CS(2) reaction is investigated by using various quantum chemical methods including CCSD(T), QCISD(T), CCSD, QCISD, G3B3, MPWB1K, BB1K, MP2, and B3LYP. The thermal rate coefficients for the formation of three major products, CS + SO ((3)Σ(-)), OCS + S ((3)P) and CO + S(2) ((3)Σ(-)(g)) were computed by using transition state and RRKM statistical rate theories over the temperature range of 200-2000 K. The computed k(SO + CS) by using high-level quantum chemical methods is in accordance with the available experimental data. The calculated rate coefficients for the formation of OCS + S ((3)P) and CO + S(2) ((3)Σ(-)(g)) are much lower than k(SO + CS); hence, it is predicted that these two product channels do not contribute significantly to the overall rate coefficient. 相似文献
414.
Nosonovsky M Hejazi V Nyong AE Rohatgi PK 《Langmuir : the ACS journal of surfaces and colloids》2011,27(23):14419-14424
The lotus effect involving roughness-induced superhydrophobicity is a way to design nonwetting, self-cleaning, omniphobic, icephobic, and antifouling surfaces. However, such surfaces require micropatterning, which is extremely vulnerable to even small wear rates. This limits the applicability of the lotus effects to situations when wear is practically absent. To design sustainable superhydrophobic surfaces, we suggest using metal matrix composites (MMCs) with hydrophobic reinforcement in the bulk of the material, rather than only at its surface. Such surfaces, if properly designed, provide roughness and heterogeneity needed for superhydrophobicity. In addition, they are sustainable, since when the surface layer is deteriorated and removed due to wear, hydrophobic reinforcement and roughness remains. We present a model and experimental data on wetting of MMCs. We also conducted selected experiments with graphite-reinforced MMCs and showed that the contact angle can be determined from the model. In order to decouple the effects of reinforcement and roughness, the experiments were conducted for initially smooth and etched matrix and composite materials. 相似文献
415.
Abolghasem BakhodaNasser Safari Vahid AmaniHamid Reza Khavasi Mahin Gheidi 《Polyhedron》2011,30(17):2950-2956
Homo bi-copper complexes [Cu2{PhP(2-py)2}2(NO3)3] (1) and [Cu2{P(2-py)3}2Cl2] (2), were synthesized from the reaction of Cu(NO3)2·3H2O and CuCl2·2H2O with their corresponding 2-pyridylphosphine ligands. Compound 1 has a mixed valence Cu(I)-Cu(II) core with electron acceptor phosphine atoms and two NO3− anions coordinated in a monodentate fashion to Cu(I), giving it a distorted tetrahedral geometry. The environment of Cu(II) in 1 is composed of four nitrogen atoms from pyridyl and another NO3− anion in a square pyramidal geometry. This complex shows luminescence and a low energy absorption band at 969 nm corresponding to intermetallic electron transfer between the copper centers. Complex 2 was prepared from the treatment of copper(II) chloride with tris(2-pyridyl)phosphine, producing a binuclear copper complex which possesses a crystallographic inversion center. The copper geometry in this complex is distorted tetrahedral with coordination of one Cl−, two nitrogens from one bridging tris(2-pyridyl)phosphine ligand and one P atom from the other bridging tris(2-pyridyl)phosphine ligand, in a similar way observed in related complexes. The products have been characterized by spectroscopic methods and also by the single-crystal X-ray diffraction method. 相似文献
416.
In this study, dispersive liquid-liquid microextraction (DLLME) combined with inductively coupled plasma optical emission spectrometry (ICP-OES) was developed for simultaneous preconcentration and trace determination of chromium, copper, nickel and zinc in water samples. Sodium diethyldithiocarbamate (Na-DDTC), carbon tetrachloride and methanol were used as chelating agent, extraction solvent and disperser solvent, respectively. The effective parameters of DLLME such as volume of extraction and disperser solvents, pH, concentration of salt and concentration of the chelating agent were studied by a (2f−1) fractional factorial design to identify the most important parameters and their interactions. The results showed that concentration of salt and volume of disperser solvent had no effect on the extraction efficiency. In the next step, central composite design was used to obtain optimum levels of effective parameters. The optimal conditions were: volume of extraction solvent, 113 μL; concentration of the chelating agent, 540 mg L−1; and pH, 6.70. The linear dynamic range for Cu, Ni and Zn was 1-1000 μg L−1 and for Cr was 1-750 μg L−1. The correlation coefficient (R2) was higher than 0.993. The limits of detection were 0.23-0.55 μg L−1. The relative standard deviations (RSDs, C = 200 μg L−1, n = 7) were in the range of 2.1-3.8%. The method was successfully applied to determination of Cr, Cu, Ni and Zn in the real water samples and satisfactory relative recoveries (90-99%) were achieved. 相似文献
417.
Kazem D. Safa J. Vahid Mardipour Yones Mosaei Oskoei 《Journal of organometallic chemistry》2011,696(3):802-806
The Peterson olefination reaction of terephthalaldehyde with tris(trimethylsilyl)methyl lithium, (Me3Si)3CLi, in THF at 0 °C gives 4-[2,2-bis(trimethylsilyl)ethenyl]benzaldehyde (1) and 4,4-bis[2,2-bis(trimethylsilyl)ethenyl]benzene (2). The new aldehyde (1) reacts with variety of amines in ethanol to afford the corresponding imines (3) containing vinylbis(trimethylsilyl) group. The newly synthesized imines (3) can be completely converted into amines containing vinylbis(trimethylsilyl) group with an excess amount of NaBH4. In the case of N-[4-(2,2-bis(trimethylsilyl)ethenyl)benzyl]-2,6-dimethylaniline LiAlH4 was used as a reducing agent in THF. 相似文献
418.
Dr. Raju Bej Dr. Chuanxiong Nie Dr. Kai Ludwig Dr. Vahid Ahmadi Dr. Jakob Trimpert Julia M. Adler Dr. Tatyana L. Povolotsky Dr. Katharina Achazi Marten Kagelmacher Ricardo Martin Vidal Dr. Jens Dernedde Dr. Benedikt B. Kaufer Prof. Dr. Rainer Haag 《Angewandte Chemie (International ed. in English)》2023,62(29):e202304010
Mucins are the key component of the defensive mucus barrier. They are extended fibers of very high molecular weight with diverse biological functions depending strongly on their specific structural parameters. Here, we present a mucin-inspired nanostructure, produced via a synthetic methodology to prepare methacrylate-based dendronized polysulfates ( MIP-1 ) on a multi gram-scale with high molecular weight (MW=450 kDa) and thiol end-functionalized mucin-inspired polymer ( MIP ) via RAFT polymerization. Cryo-electron tomography (Cryo-ET) analysis of MIP-1 confirmed a mucin-mimetic wormlike single-chain fiber structure (length=144±59 nm) in aqueous solution. This biocompatible fiber showed promising activity against SARS-CoV-2 and its mutant strain, with a remarkable low half maximal (IC50) inhibitory concentration (IC50=10.0 nM). Additionally, we investigate the impact of fiber length on SARS-CoV-2 inhibition by testing other functional polymers ( MIPs ) of varying fiber lengths. 相似文献
419.
Tayyeb Ghadimi Soheila Naderi Gharahgheshlagh Noorahmad Latifi Ahmad Hivechi Vahid Hosseinpour Sarmadi Siamak Farokh Forghani Naser Amini Peiman B. Milan Fatemeh Latifi Masoud Hamidi Ghazaleh Larijani Seyed Mohammad Amin Haramshahi Motahareh Abdollahi Fatemeh Ghadimi Saeed Nezari 《Macromolecular bioscience》2023,23(9):2300033
Burn is one of the physically debilitating injuries that can be potentially fatal; therefore, providing appropriate coverage in order to reduce possible mortality risk and accelerate wound healing is mandatory. In this study, collagen/exo-polysaccharide (Col/EPS 1–3%) scaffolds are synthesized from rainbow trout (Oncorhynchus mykiss) skins incorporated with Rhodotorula mucilaginosa sp. GUMS16, respectively, for promoting Grade 3 burn wound healing. Physicochemical characterizations and, consequently, biological properties of the Col/EPS scaffolds are tested. The results show that the presence of EPS does not affect the minimum porosity dimensions, while raising the EPS amount significantly reduces the maximum porosity dimensions. Thermogravimetric analysis (TGA), FTIR, and tensile property results confirm the successful incorporation of the EPS into Col scaffolds. Furthermore,the biological results show that the increasing EPS does not affect Col biodegradability and cell viability, and the use of Col/EPS 1% on rat models displays a faster healing rate. Finally, histopathological examination reveals that the Col/EPS 1% treatment accelerates wound healing, through greater re-epithelialization and dermal remodeling, more abundant fibroblast cells and Col accumulation. These findings suggest that Col/EPS 1% promotes dermal wound healing via antioxidant and anti-inflammatory activities, which can be a potential medical process in the treatment of burn wounds. 相似文献