排序方式: 共有70条查询结果,搜索用时 46 毫秒
31.
Rui Chang Young Pyo Hong Stephanus Axnanda Baohua Mao Naila Jabeen Suidong Wang Renzhong Tai Zhi Liu 《Current Applied Physics》2012,12(5):1292-1296
We report Ambient pressure X-ray Photoelectron Spectroscopy Endstation with an integrated chemical analytical system that consists of a residual gas analyzer in the 2nd differential pumping stage and a new low-reactive sample holder heating assembly. This system has a linear response to the reaction chamber gas pressure. The sample heating assembly also has a low dark reaction rate up to 400 °C for H2 and CO oxidation. We expect this chemical analytical system will expand our capabilities in conducting in-operando catalysis research. 相似文献
32.
Shakeela Jabeen Alexander Greer Kathleen F. Edwards Joel F. Liebman 《Photochemistry and photobiology》2020,96(5):1140-1143
A unique approach is used to relate the HOMO-LUMO energy difference to the difference between the ionization potential (IP) and electron affinity (EA) to assist in deducing not only the colors, but also chromophores in elemental nonmetals. Our analysis focuses on compounds with lone pair electrons and σ electrons, namely X2 (X = F, Cl, Br, I), S8 and P4. For the dihalogens, the [IP – EA] energies are found to be: F2 (12.58 eV), Cl2 (8.98 eV), Br2 (7.90 eV), I2 (6.78 eV). We suggest that the interahalogen X–X bond itself is the chromophore for these dihalogens, in which the light absorbed by the F2, Cl2, Br2, I2 leads to longer wavelengths in the visible by a π → σ* transition. Trace impurities are a likely case of cyclic S8 which contains amounts of selenium leading to a yellow color, where the [IP – EA] energy of S8 is found to be 7.02 eV. Elemental P4 with an [IP – EA] energy of 9.09 eV contains a tetrahedral and σ aromatic structure. In future work, refinement of the analysis will be required for compounds with π electrons and σ electrons, such as polycyclic aromatic hydrocarbons (PAHs). 相似文献
33.
An attempt has been made to incorporate intercalation power of metal-flavonoids (metal-Fls) into ds.DNA for selective accumulation of heavy metal ions on DNA trapping water insoluble (3-aminopropyl)triethoxysilane (APTES) films. Three flavonoids (Fls) namely primuletin (prim), morin (mor) and quercetin (quer) were used to chelate heavy metal ions alone and through calf thymus DNA intercalation. Metal ion (M?=?Cu2+, Fe3+, Cr3+, As2+, Hg2+, Pb2+, Cd2+, Sb5+) captured from 10?µM solution of its salt over Fl-DNA-APTES film was found to be more efficient towards metal ion removal (99% removal) than M-Fl interaction into DNA-APTES (80% removal) which in turn was better than M-Fl-DNA trapping into APTES (60% removal). M-Fl chelation was 1:1 for all the complexes and binding strength (Kb in M?1) was of the order of 103–105 for different flavonoids (Fls) and the flavonoid-chelated metals (M-Fls). From the results, it was inferred that the nature of interaction between different constituents and metal chelation with the flavonoid are the key factors that affect the ion removal efficiency. It was also anticipated that any flavonoid can be used for ion removal process subject to its affinity strength towards the ion of interest. The work successfully demonstrated the usefulness of the method for ion removal in chemical, biological and environmental systems. 相似文献
34.
Muhammad H. Sultan Shamama Javed Osama Ali Madkhali Mohammad Intakhab Alam Yosif Almoshari Mohammad Ali Bakkari Durgaramani Sivadasan Ahmad Salawi Ameena Jabeen Waquar Ahsan 《Molecules (Basel, Switzerland)》2022,27(6)
The present study aimed to develop a local dental nanoemulgel formulation of Nigella sativa oil (NSO) for the treatment of periodontal diseases. NSO purchased from a local market was characterized using a GC–MS technique. A nanoemulsion containing NSO was prepared and incorporated into a methylcellulose gel base to develop the nanoemulgel formulation. The developed formulation was optimized using a Box–Behnken statistical design (quadratic model) with 17 runs. The effects of independent factors, such as water, oil, and polymer concentrations, were studied on two dependent responses, pH and viscosity. The optimized formulation was further evaluated for droplet size, drug release, stability, and antimicrobial efficacy. The developed formulation had a pH of 7.37, viscosity of 2343 cp, and droplet size of 342 ± 36.6 nm. Sustained release of the drug from the gel for up to 8 h was observed, which followed Higuchi release kinetics with non-Fickian diffusion. The developed nanoemulgel formulation showed improved antimicrobial activity compared to the plain NSO. Given the increasing emergence of periodontal diseases and antimicrobial resistance, an effective formulation based on a natural antibacterial agent is warranted as a dental therapeutic agent. 相似文献
35.
Danish M. Jabeen N. Raza M. A. Mumtaz M. W. Tahir M. N. 《Russian Journal of General Chemistry》2021,91(2):294-301
Russian Journal of General Chemistry - In this study sulfonamide ligand, 3-methyl-2-(phenylsulfonamido)butanoic acid, has been synthesized and introduced in complexation with metals Cu, Zn, Fe, Ni,... 相似文献
36.
Sumaira Qayyum Tasawar Hayat Sumaira Jabeen Ahmed Alsaedi 《Mathematical Methods in the Applied Sciences》2020,43(9):5657-5672
Research on optimization of entropy generation in nanofluid flow gained much interest. In this study, the Walter's-B nanofluid flow is considered to analyze the irreversibility in cubic autocatalysis. Fluid motion is considered in presence of viscous dissipation, magnetohydrodynamics (MHD), radiation, and heat generation absorption. Homotopy analysis method (HAM) is employed to solve nonlinear ordinary differential system. Results show that fluid flow reduces for larger Weissenberg and Hartman numbers. Temperature gradually enhances for larger Weissenberg number and radiation parameter. For higher estimation of thermophoresis parameter, the temperature and concentration are enhanced. Opposite impact of Hartman and Weissenberg numbers is noticed for entropy generation and Bejan number. Disorderedness and Bejan number are reduced near the sheet, while the opposite trend is seen away from the sheet. 相似文献
37.
Muhammad Najam-ul-Haq Fahmida Jabeen Dilshad Hussain Adeela Saeed Syed Ghulam Musharraf Christian W. Huck Günther K. Bonn 《Analytica chimica acta》2012
Protein phosphorylation is one of the most important post-translational modifications. Phosphorylated peptides are present in low abundance in blood serum but play a vital role in regulatory mechanisms and may serve as casual factors in diseases. The enrichment and analysis of phosphorylated peptides directly from human serum and mapping the phosphorylation sites is a challenging task. Versatile nanocomposites of different materials have been synthesized using simple but efficient methodologies for their enrichment. The nanocomposites include magnetic, coated, embedded as well as chemically derivatized materials. Different base materials such as polymers, carbon based and metal oxides are used. The comparison of nanocomposites with respective nanoparticles provides sufficient facts about their efficiency in terms of loading capacity and capture efficiency. The cost for preparing them is low and they hold great promise to be used as chromatographic materials for phosphopeptide enrichment. This review gives an overview of different nanocomposites in phosphoproteomics, discussing the improved efficiency than the individual counterparts and highlighting their significance in phosphopeptide enrichment. 相似文献
38.
M. Rasul Jan Farah Jabeen Jasmin Shah Fazal Mabood 《Journal of Thermal Analysis and Calorimetry》2010,101(1):303-308
An environment friendly method, thermal catalytic pyrolysis of used isobutyl isoprene rubber was investigated. In this method,
the used inner butyl tube rubbers were catalytically pyrolyzed into valuable hydrocarbons and carbon black. In this method,
the tube rubber was pyrolyzed both thermally (with out catalyst) and catalytically in a batch reactor under atmospheric pressure.
The effect of temperature, the amount of catalyst, and the reaction time on the yields of the pyrolyzed products were investigated.
Char yield decreased with increase of pyrolysis temperature while total gas and liquid yields increased. The liquid fraction
was obtained with boiling point up to 478 K. At optimum conditions, the liquid product was collected and analyzed for different
fuel properties. Typical analysis of the used isobutyl isoprene rubber oil for both the cases of parent and refluxed oil has
been performed. Phenols and carbonyls were quantitatively determined by spectrophotometric methods using folin-denis and phenyl
hydrazine reagents, respectively. The distillation data showed that ~100% of oil has boiling point <473 K which is the boiling
point for 80% of distilled product in commercial kerosene. Its specific gravity, viscosity, freezing point, Cetane number,
and diesel index were also within the limits of kerosene. 相似文献
39.
Muhammad Najam‐ul‐Haq Adeela Saeed Fahmida Jabeen Dilshad Hussain Naseem Khan Maryam Shabir Nadeem Raza Muhammad Naeem Ashiq Muhammad Aslam Malana Zafar Iqbal Zafar 《Biomedical chromatography : BMC》2015,29(7):981-989
Determination of the availability of phases for specific separations is an important task achieved by a separation chemist. This becomes vital when the complex samples like biofluids are dealt with in proteome science. The work presented here involves the synthesis and application of terpolymeric sorbent with different functionalizations adopted for the selective enrichment of biomolecules of interest from biological fluids. Synthesis of terpolymer was carried out by the radical polymerization of monomers: methyl acrylate, acrylic acid and vinyl acetate with diethylene glycol dimethacrylate as cross‐linking agent, benzoyl peroxide as initiator and chloroform as a porogenic solvent. Characterization was done through Fourier transform infrared spectroscopy, scanning electron microscopy and nitrogen adsorption porosimetry. The polymer was further modified to immobilized metal ion affinity chromatographic material, with immobilized Fe3+/La3+ ions that allowed phosphopeptide enrichment from tryptic digests of standard proteins as well as milk, egg yolk and human serum. Sensitivity of enrichment down to 50 fmol was achieved in the presence of complex protein background as bovine serum albumin. Hydrophobicity was introduced through octadecyl amine, which provides comparable results to ZipTip C18/C4 for desalting of complex mixtures of all caseins. Analysis of the enriched content was performed by Matrix Assisted Laser Desorption Ionization Mass Spectrometry (MALDI‐MS). Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
40.
Muhammad Salman Sajid Fahmida Jabeen Dilshad Hussain Qurra‐tul‐Ann Afza Gardner Muhammad Naeem Ashiq Muhammad Najam‐ul‐Haq 《Journal of separation science》2020,43(7):1348-1355
Enrichment of glycoproteins has been important because of their dynamicity and role in biological systems. Study of glycoproteins is complex because of the simultaneous glycosylation and deglycosylation inside the body. Often employed affinities for glycopeptides are hydrazide, boronic acid, or physiosorbed lectin on support materials. Cellulose, a natural polysaccharide, has rich surface chemistry, stable structure, low cost and availability in different variants. In present study, fibrous cellulose is oxidized using periodate to modify with boronic acid. Attachment of boronic acid is confirmed by Fourier transform infrared spectroscopy. Particle size and morphology of boronic acid@fibrous cellulose is studied by scanning electron microscopy. The enrichment efficiency is evaluated by using horseradish peroxidase as model protein. Boronic acid@fibrous cellulose is selective up to 1:250 for spiked horseradish peroxidase in bovine serum albumin digest, sensitive down to 0.1 femtomol and recovering 88.15% glycopeptides. Moreover, protein binding capacity is determined as 213 mg/g and 41% sequence coverage of horseradish peroxidase protein with all eight glycosylation sites detected. Total of 18 glycopeptides are enriched from immunoglobulin digest showing ability of boronic acid@fibrous cellulose to enrich glycoproteins from multiglycoforms. Enrichment from human serum recovers 18% extracellular and 72% secreted glycoproteins via bottom‐up approach and online tools. 相似文献