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排序方式: 共有182条查询结果,搜索用时 15 毫秒
91.
Sultana Ferdous Marios A. Ioannidis Dale E. Henneke 《Journal of nanoparticle research》2012,14(5):850
The effects of temperature, pH and sodium chloride (NaCl) concentration on the equilibrium and dynamic interfacial tension (IFT) of 4.4-nm gold nanoparticles capped with n-dodecanethiol at hydrocarbon–water interfaces was studied. The pendant drop technique was used to study the adsorption properties of these nanoparticles at the hexane–water and nonane–water interfaces. The physical size of the gold nanoparticles was determined by TEM image analysis. The interfacial properties of mixtures of these nanoparticles, having different sizes and capping agents, were then studied. The addition of NaCl was found to cause a decrease of the equilibrium and dynamic IFT greater than that which accompanies the adsorption of nanoparticles at the interface in the absence of NaCl. Although IFT values for acidic and neutral conditions were found to be similar, a noticeable decrease in the IFT was found for more basic conditions. Increasing the temperature of the system was found to cause an increase in both dynamic and equilibrium IFT values. These findings have implications for the self-assembly of functionalized gold nanoparticles at liquid–liquid interfaces. 相似文献
92.
AbstractIn this paper, the equivalence between multi-valued maps satisfying the Mizoguchi-Takahashi’s uniformly locally contractive condition and multi-valued maps satisfying the Nadler’s uniformly locally contractive condition is obtained on metrically convex space. We have provided examples to illustrate that this equivalence need not be true on any arbitrary metric space. 相似文献
93.
In some recent derivations thermal characters of the inner horizon have been employed; however, the understanding of possible role that may play the inner horizons of black holes in black hole thermodynamics is still somewhat incomplete. Motivated by this problem we investigate Hawking radiation of the Reissner-Nordström-Taub-NUT (RNTN) black hole by considering thermal characters of both the outer and inner horizons. We apply Damour-Ruffini method and the thin film brick wall model to calculate the temperature and the entropy of the inner horizon of the RNTN black hole. The inner horizon admits thermal character with positive temperature and entropy proportional to its area, and it thus may contribute to the total entropy of the black hole in the context of Nernst theorem. Considering conservations of energy and charge and the back-reaction of emitting particles to the spacetime, the emission spectra are obtained for both the inner and outer horizons. The total emission rate is the product of the emission rates of the inner and outer horizons, and it deviates from the purely thermal spectrum and can bring some information out. Thus, the result can be treated as an explanation to the information loss paradox. 相似文献
94.
Shabir G Anwar F Sultana B Khalid ZM Afzal M Khan QM Ashrafuzzaman M 《Molecules (Basel, Switzerland)》2011,16(9):7302-7319
This paper describes the antioxidant and antimicrobial activities and phenolic components of different solvent (absolute methanol, absolute ethanol, absolute acetone, 80% methanol, 80% ethanol, 80% acetone and deionized water) extracts of leaves, flowers and bark of Gold Mohar [Delonix regia (Bojer ex Hook.) Raf.]. The extract yields from leaves, flowers and bark ranged from 10.19 to 36.24, 12.97 to 48.47 and 4.22 to 8.48 g/100 g dry weight (DW), respectively. Overall, 80% methanol extract produced from the leaves exhibited significantly (P < 0.05) higher antioxidant activity, with high phenolic contents (3.63 g GAE/100 g DW), total flavonoid contents (1.19 g CE/100 g DW), inhibition of peroxidation (85.54%), DPPH scavenging capacity (IC(50) value 8.89 μg/mL) and reducing power (1.87). Similarly, this 80% methanol leaves extract also showed superior antimicrobial activity. HPLC analysis of the 80% methanol extracts for individual phenolics revealed the presence of gallic, protocatechuic and salicylic acid in leaves; gallic, protocatechuic, salicylic, trans-cinnamic and chlorogenic acid in flowers, and gallic acid in bark as the main (amount > 1.50 mg/100 g DW) phenolic acids. Besides, small amounts ( < 1.50 mg/100 g DW) of some other phenolic acids such as sorbic, sinapic, p-coumaric, m-coumaric, ferulic, caffeic, 3-hydroxybenzoic, 4-hydroxycinnamic and 4-hydroxybenzoic acids were also detected. The extracts of the tested parts of Gold Mohar, especially, the leaves, might be valuable for functional food and therapeutic applications. 相似文献
95.
Shahid Hussain Arshad Muhammad Nawaz Naeem Nazra Sultana Abdul Ghafar Shah Zafar Iqbal 《Archive of Applied Mechanics (Ingenieur Archiv)》2011,81(3):319-343
In the present study, a vibration frequency analysis of a bi-layered cylindrical shell composed of two independent functionally
graded layers is presented. The thickness of the shell layers is assumed to be equal and constant. Material properties of
the constituents of bi-layered functionally graded cylindrical shell are assumed to vary smoothly and continuously through
the thickness of the layers of the shell and are controlled by volume fraction power law distribution. The expressions for
strain–displacement and curvature–displacement relationships are utilized from Love’s first approximation linear thin shell
theory. The versatile Rayleigh–Ritz approach is employed to formulate the frequency equations in the form of eigenvalue problem.
Influence of material distribution in the two functionally graded layers of the cylindrical shells is investigated on shell
natural frequencies for various shell parameters with simply supported end conditions. To check the validity, accuracy and
efficiency of the present methodology, results obtained are compared with those available in the literature. 相似文献
96.
Two new flavonoids were isolated from the flowers of Punica granatum Linn. (Punicaceae) along with the known compounds ellagic acid, gallic acid, sucrose, and gallic acid glycoside. The structures
of the new flavonoids have been characterized as 5,6,7,8,2′,3′,5′-heptahydroxy-4′-methoxyflavanone (punicaflavanol) and 5,6,7,8,2′,5′-hexahydroxy-4′-methoxyflavanone-7-β-D-xylopyranoside (granatumflavanyl xyloside) on the basis of spectral data analyses and chemical reactions. 相似文献
97.
An accurate, sensitive and least time consuming reverse phase high performance liquid chromatographic (RP‐HPLC) method for the estimation of captopril in the presence of non steroidal anti‐inflammatory drugs in formulation and human serum has been developed and validated. Chromatographic separation was conducted on prepacked Purospher star C18 (5 μm, 25 × 0.46 cm) column at room temperature using methanol:water (80:20 v/v) as a mobile phase, pH adjusted at 2.8 with o‐phosphoric acid and at a flow rate of 1.0 mL min−1, while UV detection was performed at 227 nm. The limit of detection and quantification for captopril were 1 and 0.35 ng mL−1, while that for (NSAID's) i.e. flurbiprofen, ibuprofen, diclofenac sodium and mefenamic acid LOD were 0.2, 1, 2 and 0.4 ng mL−1 respectively and LOQ were 0.9, 2.9, 8 and 1 ng mL−1 Analytical recovery was > 98.1%. The method used for the quantitative analysis of commonly administered non steroidal anti‐inflammatory drugs (NSAID's) i.e. ibuprofen, flurbiprofen, diclofenac sodium and mefenamic acid alone or in combination with captopril from API (active pharmaceutical ingredients), dosage formulations and in human serum. The established method is rapid (RT < 12 min), accurate (recovery > 98.1%), selective (no interference of excepients and other commonly used drugs and food) and sensitive (LOQ 3.5 ng mL;‐1) and reproducible (SD ± 0.003). 相似文献
98.
Bouzebda Salim Chaouch Mohamed Biha Sultana Didi 《Annals of the Institute of Statistical Mathematics》2022,74(4):737-771
Annals of the Institute of Statistical Mathematics - The main purpose of the present work is to investigate kernel-type estimate of a class of function derivatives including parameters such as the... 相似文献
99.
Dr. S. M. A. Hakim Siddiki Dr. Abeda Sultana Touchy Dr. Kenichi Kon Prof. Ken‐ichi Shimizu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(17):6111-6119
Carbon‐supported Pt nanoparticles (Pt/C) were found to be effective heterogeneous catalysts for the direct Julia olefination of alcohols in the presence of sulfones and KOtBu under oxidant‐free conditions. Primary alcohols, including aryl, aliphatic, allyl, and heterocyclic alcohols, underwent olefination with dimethyl sulfone and aryl alkyl sulfones to give terminal and internal olefins, respectively. Secondary alcohols underwent methylenation with dimethyl sulfone. Under 2.5 bar H2, the same reaction system was effective for the transformation of alcohol OH groups to alkyl groups. Structural and mechanistic studies of the terminal olefination system suggested that Pt0 sites on the Pt metal particles are responsible for the rate‐limiting dehydrogenation of alcohols and that KOtBu may deprotonate the sulfone reagent. The Pt/C catalyst was reusable after the olefination, and this method showed a higher turnover number (TON) and a wider substrate scope than previously reported methods, which demonstrates the high catalytic efficiency of the present method. 相似文献
100.
We investigate Hawking radiation of charged and magnetized (scalar /fermion) particles from Demiański-Newman (DN) black holes using Hamilton-Jacobi (HJ) ansatz. Taking into account conservation of energy and the backreaction of particles to the spacetime, we calculate the emission rate and find it proportional to the change of Bekenstein-Hawking entropy. The radiation spectrum deviates from the precisely thermal one and is accordant with that obtained by the null geodesic method, but its physical picture is more clear. The investigation specifies a quantum-corrected radiation temperature dependent on the black hole background and the radiation particle’s energy, angular momentum, and charges. 相似文献