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131.
Tahair Rasham Abdullah Shoaib Nawab Hussain Muhammad Arshad Sami Ullah Khan 《Journal of Fixed Point Theory and Applications》2018,20(1):45
In this article, common fixed point theorems for a pair of multivalued mappings satisfying a new Ciric-type rational F-contraction condition in complete dislocated metric spaces are established. An example is constructed to illustrate our results. An application to the system of integral equations is presented to support the usability of proved results. Our results combine, extend and infer several comparable results in the existing literature. 相似文献
132.
133.
Tanveer Hussain Bokhari A. Mushtaq Islam Ullah Khan 《Journal of Radioanalytical and Nuclear Chemistry》2010,285(2):389-398
In this work, sorption of Ni(II) from aqueous solution to goethite as a function of various water quality parameters and temperature
was investigated. The results indicated that the pseudo-second-order rate equation fitted the kinetic sorption well. The sorption
of Ni(II) to goethite was strongly dependent on pH and ionic strength. A positive effect of HA/FA on Ni(II) sorption was found
at pH < 8.0, whereas a negative effect was observed at pH > 8.0. The Langmuir, Freundlich, and D-R models were applied to
simulate the sorption isotherms at three different temperatures of 293.15 K, 313.15 K and 333.15 K. The thermodynamic parameters
(ΔH
0, ΔS
0 and ΔG
0) were calculated from the temperature dependent sorption, and the results indicated that the sorption was endothermic and
spontaneous. At low pH, the sorption of Ni(II) was dominated by outer-sphere surface complexation or ion exchange with Na+/H+ on goethite surfaces, whereas inner-sphere surface complexation was the main sorption mechanism at high pH. 相似文献
134.
135.
136.
Hiroyuki Takemura Teruo Shinmyozu Hirokazu Miura Islam Ullah Khan Takahiko Inazu 《Journal of inclusion phenomena and macrocyclic chemistry》1994,19(1-4):193-206
Side arm modifications of hexahomotriazacalix[3]arene (1) were achieved by simple synthetic methods. Compound5 has picolyl side arms and liquid-liquid extraction experiments showed that the alkali cation affinity of5 is much stronger than that of1. A chiral group was also introduced into the azacalixarene structure. Calix[4]arene was converted into dihomoazacalix[4]arene (2) in 8% yield. Clathrate formation of2 with various solvents is described. MM3 calculations were carried out onp-substituted analogs of2. The self-filled structure, in which the benzyl side arm is placed in its cavity, is the most stable structure when thep-positions of the aromatic rings carry small substituents. Strong hydrogen bonds between nitrogen and phenolic hydroxyl groups in dihomoazacalix[4]arene (2) were observed at low temperatures. The1H-NMR signals of phenolic hydroxyl groups appeared as six singlets in the range of 9.817.1 ppm at –70°C.This paper is dedicated to the commemorative issue on the 50th anniversary of calixarenes. 相似文献
137.
Xuefei Xu Habib Ullah Muhammad Humayun Linfeng Li Xia Zhang Mohamed Bououdina Damien P. Debecker Kaifu Huo Deli Wang Chundong Wang 《Advanced functional materials》2023,33(44):2303986
Constructing multiple heterogeneous structures allows for improving the electrocatalytic activity of NiO by incorporating multiple active sites. Unfortunately, the poor conductivity of NiO makes efficient charge transfer within the heterogeneous structures difficult, thereby inhibiting the improvement of its intrinsic activity. Herein, F-doped NiO/Ni@C heterogeneous catalyst (F-NiO/Ni@C) is fabricated via a new organic-inorganic hybrid approach, showing both advanced hydrogen evolution reaction (HER) and urea oxidation reaction (UOR) activity. The targeted F-doping increases electron delocalization, and facilitates electron transfer from Ni to NiO at the nano-interfaces. This interphase synergy provides ready-to-use F-NiO active sites, allowing F-NiO/Ni@C to achieve optimum H* adsorption Gibbs free energy for HER and a lower energy barrier for UOR. As a result, the as-configured F-NiO/Ni@C || F-NiO/Ni@C cell requires an ultra-low cell voltage of 1.37 V to achieve 10 mA cm−2 in alkaline media (with 0.3 M urea), outperforming the state-of-the-art benchmark Pt/C|| RuO2 cell (1.45 V). This study reveals the positive impact of anion doping on interphase synergy and provides useful guidelines for designing monometallic catalysts for UOR as well as hydrogen generation. 相似文献
138.
Ahmad VU Hussain J Hussain H Jassbi AR Ullah F Lodhi MA Yasin A Choudhary MI 《Chemical & pharmaceutical bulletin》2003,51(6):719-723
Three new diterpene esters with a myrsinol-type skeleton have been isolated from Euphorbia decipiens BOISS. & BUHSE. The structure elucidation of the isolated compounds was based primarily on two-dimensional (2D)-NMR techniques including correlation spectroscopy (COSY), heteronuclear multiple quantum coherence (HMQC), heteronuclear multiple bond correlation (HMBC) and nuclear Overhauser effect spectroscopy (NOESY) experiments. Compounds 1 and 3 are active against prolyl endopeptidase and compound 2 showed inhibitory activity against urease enzyme. 相似文献
139.
140.
Ibrahim El-Tantawy El Sayed Sami Ullah Omar A. Al-Hartomy Asmaa Mohammed Hasanein Abdullah A. S. Ahmed Khaled A. Kahilo Mehrez E. El-Naggar 《Molecules (Basel, Switzerland)》2022,27(3)
The naturally occurring neocryptolepine (5-Methylindolo [2,3-b]quinoline) and its analogs exhibited prominent anticancer and antimalarial activity. However, the main problem of this class of compounds is their poor aqueous solubility, hampering their bioavailability and preventing their clinical development. To overcome the problem of insolubility and to improve the physicochemical and the pharmacological properties of 5-Methylindolo [2,3-b]quinoline compounds, this work was designed to encapsulate such efficient medical compounds into mesoporous silica oxide nanoemulsion (SiO2NPs). Thus, in this study, SiO2NPs was loaded with three different concentrations (0.2 g, 0.3, and 0.6 g) of 7b (denoted as NPA). The findings illustrated that the nanoparticles were formed with a spherical shape and exhibited small size (less than 500 nm) using a high concentration of the synthesized chemical compound (NPA, 0.6 g) and good stabilization against agglomeration (more than −30 mv). In addition, NPA-loaded SiO2NPs had no phase separation as observed by our naked eyes even after 30 days. The findings also revealed that the fabricated SiO2NPs could sustain the release of NPA at two different pH levels, 4.5 and 7.4. Additionally, the cell viability of the produced nanoemulsion system loaded with different concentrations of NPA was greater than SiO2NPs without loading, affirming that NPA had a positive impact on increasing the safety and cell viability of the whole nanoemulsion. Based on these obtained promising data, it can be considered that the prepared NPA-loaded SiO2NPs seem to have the potential for use as an effective anticancer drug nanosystem. 相似文献