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31.
Matiullah Khan Wenbin Cao Ning Chen Zahid Usman Dil Faraz Khan Arbab Mohammad Toufiq Murad Ali Khaskheli 《Current Applied Physics》2013,13(7):1376-1382
The structural, electronic and optical properties of tungsten-doped TiO2 have been investigated using density functional theory with plane wave basis sets and ultrasoft pseuodopotential. Substitutional W doping at Ti sites create W 5d states just below the conduction band minimum while interstitial W doping gives isolated W 5d states in the middle of forbidden region. Averaged bond lengths show that W doping at Ti sites produce minimum structural distortion as compared to the interstitial W-doped TiO2. Substitutional W-doped TiO2 has better visible light absorption compared to interstitial W-doped TiO2 and has stable configuration which provide reasonable explanation for the experimental findings. Tungsten doping in TiO2 with different doping concentrations is investigated as an enabling concept for enhancing the visible light absorption. Optical properties show that optimal W doping concentration would improve the visible light absorption. 2.08% W doping concentration gives strong visible and ultraviolet light absorption among all doped models found consistent with experiments. 相似文献
32.
The purpose of the present study is to determine the elemental composition of Pakistani cement brands using calibration-free laser induced breakdown spectroscopy (CF-LIBS) and to compare the obtained results with the other analytical techniques such as, laser ablation – time-of-flight – mass spectrometry (LA-TOF-MS), energy dispersive X-ray spectrometry (EDX), X-ray fluorescence spectroscopy (XRF) and proton induced X-ray emission spectrometry (PIXE). Compositional results reveal that all the cement brands are mainly composed of calcium, silicon, iron, aluminum, magnesium, potassium, sodium, titanium, lithium and strontium with varying concentrations. The compositions obtained by LIBS and LA-TOF-MS are in good agreement with results obtained by the other standard techniques and demonstrate the potential use of LIBS for the online monitoring of industrial cement production. 相似文献
33.
Muhammad Umair Hanif Adnan Yaseen Roquyya Gul Muhammad Usman Mirza Muhammad Hassan Nawaz Syed Shoaib Ahmed Salman Aziz Saima Chaudhary Ayyaz Ali Khan Muhammad Shoaib 《Applied biochemistry and biotechnology》2018,186(1):256-270
Small ubiquitin-like modifier (SUMO) fusion technology is widely used in the production of heterologous proteins from prokaryotic system to aid in protein solubilization and refolding. Due to an extensive clinical application of human bone morphogenetic protein 2 (hBMP2) in bone augmentation, total RNA was isolated from human gingival tissue and mature gene was amplified through RT-PCR, cloned (pET21a), sequence analyzed, and submitted to GenBank (Accession no. KF250425). To obtain soluble expression, SUMO3 was tagged at the N-terminus of hBMP2 gene (pET21a/SUMO3-hBMP2), transferred in BL21 codon+, and ~?40% soluble expression was obtained on induction with IPTG. The dimerized hBMP2 was confirmed with Western blot, native PAGE analysis, and purified by fast protein liquid chromatography with 0.5 M NaCl elution. The cleavage of SUMO3 tag from hBMP2 converted it to an insoluble form. Computational 3D structural analysis of the SUMO3-hBMP2 was performed and optimized by molecular dynamic simulation. Protein-protein interaction of SUMO3-hBMP2 with BMP2 receptor was carried out using HADDOCK and inferred stable interaction. The alkaline phosphatase assay of SUMO3-hBMP2 on C2C12 cells showed maximum 200-ng/ml dose-dependent activity. We conclude that SUMO3-tagged hBMP2 is more suited for generation of soluble form of the protein and addition of SUMO3 tag does not affect the functional activity of hBMP2. 相似文献
34.
Munir Ullah Khan Safir Ullah Khan Xiaohan Cao Muhammad Usman Xinchen Yue Abdul Ghaffar Muhammad Hassan Prof. Chengjian Zhang Prof. Xinghong Zhang 《化学:亚洲杂志》2023,18(1):e202201050
This study demonstrates the superiority of a stable and well-defined heterogeneous cobalt hexacyanocobaltate (Co3[Co(CN)6]2), a typical cobalt Prussian Blue Analogue (CoCo-PBA) that catalyzes the copolymerization of carbonyl sulfide (COS) and propylene oxide (PO) to produce poly(propylene monothiocarbonate)s (PPMTC). The number-average molecular weights of the PPMTC were 66.4 to 139.4 kg/mol, with a polydispersity of 2.0–3.9. The catalyst productivity reached 1040 g polymer/g catalyst (12.0 h). The oxygen-sulfur exchange reaction (O/S ER), which would generate random thiocarbonate and carbonate units, was effectively suppressed, and thus the selectivity of the monothiocarbonate over carbonate linkages was up to >99%. It was shown that no cyclic thiocarbonate byproduct was produced during the heterogeneous catalysis of COS/PO copolymerization using CoCo-PBA as the catalyst. The content of monothiocarbonate and ether units in the copolymer chain could be regulated by tuning the feeding amount of COS. 相似文献
35.
9,10‐Diphenyl‐9,10‐epidioxyanthracene and 9,10‐dihydro‐10,10‐dimethoxy‐9‐phenylanthracen‐9‐ol
Anwar Usman Hoong‐Kun Fun Yun Li Jian‐Hua Xu 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(6):o308-o310
9,10‐Diphenyl‐9,10‐epidioxyanthracene, C26H18O2, (I), was accidentally used in a photooxygenation reaction that produced 9,10‐dihydro‐10,10‐dimethoxy‐9‐phenylanthracen‐9‐ol, C22H20O3, (II). In both compounds, the phenyl rings are approximately orthogonal to the anthracene moiety. The conformation of the anthracene moiety differs as a result of substitution. Intramolecular C—H⃛O interactions in (I) form two approximately planar S(5) rings in each of the two crystallographically independent molecules. The packing of (I) and (II) consists of molecular dimers stabilized by C—H⃛O interactions and of molecular chains stabilized by O—H⃛O interactions, respectively. 相似文献
36.
37.
Abdul Mateen Maduru Suneetha Syed Shoaib Ahmad Shah Muhammad Usman Tauqeer Ahmad Iftikhar Hussain Shaukat Khan Mohammed A. Assiri Ahmed M. Hassan Muhammad Sufyan Javed Sung Soo Han Raed H. Althomali Mohammed M. Rahman 《Chemical record (New York, N.Y.)》2024,24(1):e202300235
Since the initial MXenes were discovered in 2011, several MXene compositions constructed using combinations of various transition metals have been developed. MXenes are ideal candidates for different applications in energy conversion and storage, because of their unique and interesting characteristics, which included good electrical conductivity, hydrophilicity, and simplicity of large-scale synthesis. Herein, we study the current developments in two-dimensional (2D) MXene nanosheets for energy storage and conversion technologies. First, we discuss the introduction to energy storage and conversion devices. Later, we emphasized on 2D MXenes and some specific properties of MXenes. Subsequently, research advances in MXene-based electrode materials for energy storage such as supercapacitors and rechargeable batteries is summarized. We provide the relevant energy storage processes, common challenges, and potential approaches to an acceptable solution for 2D MXene-based energy storage. In addition, recent advances for MXenes used in energy conversion devices like solar cells, fuel cells and catalysis is also summarized. Finally, the future prospective of growing MXene-based energy conversion and storage are highlighted. 相似文献
38.
We investigate self and cross-Kerr nonlinearity in a four level quantized graphene atomic medium. The absorption, dispersion, transmission and subluminal/superluminal behaviors of a probe light field are studied. An amplification of the probe light field is observed in the absorption spectrum. The normal and anomalous slope of dispersion is also investigated at the positive/negative absorption region. It is shown that Kerr nonlinearity invert and enhance the subluminal/superluminal behaviors of the pulse and self-Kerr effect is found to be more subluminal/superluminal as compared to cross-Kerr effect. The results show significant applications in information storage, self and cross phase modulation and lasing without inversion. 相似文献
39.
Eny?KusriniEmail author Muhammad?I.?Saleh Anwar?Usman 《Journal of chemical crystallography》2011,41(2):87-97
Abstract
The crystal structure and photoluminescence (PL) studies of the monomeric and dimeric Er(III) complexes with two different chelating ligands (anthracene-9-carboxylic acid, 9-ACA; pentaethylene glycol, EO5; and picric acid, HPic) are reviewed. The Er(III) metal ion was coordinated to the attached ligands in eight- and nine-coordination number. The dimeric [Er2(9-AC)6(DMF)2(H2O)2] complex shows the presence of deprotonated 9-AC anions with the negatively charged oxygen atoms bridged two Er(III) ions leads to a great coordinative flexibility via three possibilities of coordination modes, i.e. monodentate, chelation bidentate, chelating–bridging tridentate, where 9-AC = anthracene-9-carboxylate anion. The monomeric [Er(Pic)2(EO5)](Pic) complex displays the important flexible structure of the acyclic EO5 ligand and the role of Pic anions act as bidentate and monodentate chelations. The PL spectra of both Er(III) complexes show a broad band with the center peak position being dependent on the attached aromatic ligands. The heavier lanthanide complexes show the difference in structures, coordination geometry environment, and luminescence properties compared to the lighter lanthanide complexes. The energy transfer process in the complexes could be optimized with maximize the overlap between the emission spectrum of donor atom and absorption spectrum of acceptor atom. 相似文献40.
The advances in recording, editing, and broadcasting multimedia contents in digital form motivate to protect these digital contents from illegal use, such as duplication, manipulation, and redistribution. However, watermarking algorithms are designed to satisfy requirements of applications, as different applications have different concerns. We intend to design a watermarking algorithm for applications which require high embedding capacity and imperceptibility, to maintain the integrity of the host signal as well as embedded information. Reversible watermarking is a promising technique which satisfies our requirements. In this paper, we concentrate on improving the watermark capacity and reducing the perceptual degradation of an image. We investigated the Luo's [1] additive interpolation-error expansion algorithm and enhanced it by incorporating with two intelligent techniques: genetic algorithm (GA), and particle swarm optimization (PSO). Genetic algorithm is applied to exploit the correlation of image pixel values to obtain better estimation of neighboring pixel values, which results in optimal balance between information storage capacity and imperceptibility. Particle swarm optimization (intelligent technique) is also applied for the same purpose. Experimental results show that PSO and GA nearly give the same results, but GA outperforms the PSO. Experimental results also reveal that the proposed strategy outperforms the state of art works in terms of perceptual quality and watermarking payload. 相似文献