排序方式: 共有33条查询结果,搜索用时 15 毫秒
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Nida Iqbal Rabia NazirAnila Asif Aqif Anwar ChaudhryMuhammad Akram Goh Yi FanAftab Akram Rashid AminSung Ha Park Rafaqat Hussain 《Current Applied Physics》2012,12(3):755-759
Polyvinyl alcohol (PVA) coated hydroxyapatite was deposited onto a 316L stainless steel substrate by electrophoretic deposition. Deposition was carried out in a methanol suspension at pH 5.5 using a graphite rod as an anode. Parameters such as PVA concentration, deposition voltage and time were optimized to achieve a homogeneous, crack-free adhesive coating. Techniques such as X-ray diffraction and Fourier transform infrared spectroscopy were used to study the phase composition of the coated materials and the stability of hydroxyapatite in the presence of PVA. 相似文献
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Shaza M. Al-Massarani Ali A. El-Gamal Adnan J. Al-Rehaily Ebtesam S. Al-Sheddi Mai M. Al-Oqail Nida N. Farshori Alden S. Estep Nurhayat Tabanca James J. Becnel 《Molecules (Basel, Switzerland)》2021,26(4)
Chromatographic purification of the alcoholic extract from the aerial parts of the Saudi plant Nuxia oppositifolia (Hochst.), Benth., resulted in five isolated phenolic compounds. Two flavones, hispidulin (1) and jaceosidin (2), and the phenylethanoid glycosides, verbascoside (3), isoverbascoside (4), and conandroside (5), were identified and their chemical structures were determined by spectroscopic analyses. The insecticidal activity of compounds 1 and 2, in addition to 11 compounds isolated in a previous research (6–16), was evaluated against the Yellow Fever mosquito, Aedes aegypti. Four compounds displayed adulticidal activity with LD50 values of 2–2.3 μg/mosquito. Free radical scavenging properties of the plant extracts and compounds (1–5) were evaluated by measuring the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonate radical cation (ABTS•+) scavenging activity. All compounds exhibited notable activity, compared with the positive control, l-Ascorbic acid. This study suggests that N. oppositifolia could be a promising source of secondary metabolites, some with lethal adulticidal effect against Ae. aegypti. 相似文献
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Coupling of CFD Simulations and Population Balance Modeling to Predict Brownian Coagulation in an Emulsion Polymerization Reactor 下载免费PDF全文
In this study a framework consisting of a computational fluid dynamics simulation coupled to a population balance model for the modeling of emulsion polymerizations is proposed. The combined approach is used to understand the impact of changing length and time scales, as well as mixing conditions on the particle size distribution (PSD) of a polymer latex under different conditions. It is shown that the effect of agitation rate can have a profound impact on the distribution of ionic species in the reactor, and thus on the evolution of the PSD.
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Nida Sheibat‐Othman Ana‐Maria Cenacchi‐Pereira Amilton Martins Dos Santos Elodie Bourgeat‐Lami 《Journal of polymer science. Part A, Polymer chemistry》2011,49(22):4771-4784
We report the kinetics and mechanism of soap‐free emulsion polymerization of styrene using laponite platelets as stabilizers. The polymerization was initiated by potassium persulfate and the latex particles were stabilized by laponite platelets dispersed in water. Laponite adsorption on the polymer particles was enhanced by the addition of poly(ethylene glycol) monomethylether methacrylate (PEGMA). Particle nucleation can be described using the classical homogeneous nucleation mechanism followed by coagulation of unstable precursors. Oligomeric radicals formed in the water phase become insoluble and precipitate on the laponite surface leading to primary precursor particles composed of a few polymer chains and one or several clay platelets. Mature latex particles are then generated by coagulation and growth of the previously formed precursor particles. Both the nucleation and initial aggregation rates increased in the presence of PEGMA. Calorimetric monitoring of the polymerization allowed estimating the heat produced by the reaction and the monomer conversion. Hence, using the monomer material balance, the number of radicals in the polymer particles could be estimated precisely. The average number of radicals per particle, $ \bar n $ , was found to be high in the range 3–6. This result was attributed to strong attractive interactions between the growing radicals and the clay surface. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011. 相似文献
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Nida Ali Farooq-Ahmad Khan Kayode Muritala Salawu Rimsha Irshad Almas Jabeen Chun-Lei Zhang Muhammad Iqbal Choudhary Xin-Min Liu Yan Wang 《Molecules (Basel, Switzerland)》2022,27(4)
Two new ursane-type triterpenoids, named Polyanside A (1) and B (2), along with eleven known compounds (3–13), were isolated and elucidated from Maranthes polyandra (Benth.) Prance. The structures of these compounds were elucidated based on chemical evidence and multiple spectroscopic data. Isolated compounds were evaluated for anti-cancer, anti-inflammatory activities, and cytotoxicity on a normal human cell line (BJ). None of them showed activity and cytotoxicity. The hexane fraction was analyzed by GC-MS, resulting in the identification of forty-one compounds. This is the first comprehensive study on the phytochemistry of M. polyandra. 相似文献
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Nida Iftikhar Ammara Saleem Muhammad Furqan Akhtar Ghulam Abbas Shahid Shah Shabana Bibi Ghulam Md Ashraf Badrah S. Alghamdi Turki S. Abujamel 《Molecules (Basel, Switzerland)》2022,27(19)
Present research was planned to assess the in vitro and in vivo anti-arthritic potential of Caralluma tuberculata N. E. Brown. methanolic (CTME) and aqueous (CTAQ) extracts. Chemical characterization was done by high-performance liquid chromatography and gas chromatography–mass spectrometry analysis. The Complete Freund’s Adjuvant (CFA) was injected in left hind paw of rat at day 1 and dosing at 150, 300 and 600 mg/kg was started on the 8th day via oral gavage in all groups except normal and disease control rats (which were given distilled water), whereas methotrexate (intraperitoneal; 1 mg/kg/mL) was administered to standard control. The CTME and CTAQ exerted significant (p < 0.01–0.0001) in vitro anti-arthritic action. Both extracts notably reduced paw edema, and restored weight loss, immune organs weight, arthritic score, RBCs, ESR, platelet count, rheumatoid factor (RF), C-reactive protein, and WBCs in treated rats. The plant extracts showed significant (p < 0.05–0.0001) downregulation of tumor necrosis factor-α, Interleukin-6, -1β, NF-κB, and cyclooxygenase-2, while notably upregulated IL-4, IL-10, I-κBα in contrast to disease control rats. The plant extracts noticeably (p < 0.001–0.0001) restored the superoxide dismutase and catalase activities and MDA levels in treated rats. Both extracts exhibited significant anti-arthritic potential. The promising potential was exhibited by both extracts probably due to phenolic, and flavonoids compounds. 相似文献
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Suzanne C. Bell Melissa Gayton-Ely Corey M. Nida 《Analytical and bioanalytical chemistry》2009,395(2):401-409
Clandestine bomb-makers are exposed to significant amounts of explosives and allied materials. As with any ingested xenobiotic
substance, these compounds are subject to biotransformation. As such, the potential exists that characteristic suites of biomarkers
may be produced and deposited in matrices that can be exploited for forensic and investigative purposes. However, before such
assays can be developed, foundational data must be gathered regarding the toxicokinetics, fate, and transport of the resulting
biomarkers within the body and in matrices such as urine, hair, nails, sweat, feces, and saliva. This report presents an in
vitro method for simulation of human metabolic transformations using human liver microsomes and an assay applicable to representative
nitro-explosives. Control and metabolized samples of TNT, RDX, HMX, and tetryl were analyzed using high-performance liquid
chromatography coupled to tandem mass spectrometry (LC/MS/MS) and biomarkers identified for each. The challenges associated
with this method arise from solubility issues and limitations imposed by instrumentation, specifically, modes of ionization. 相似文献
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An investigation of the thionine sensitized aerobic photooxidation of thiourea was observed spectrophotometrically at a wavelength
of 598 nm. Articles reported two types of reactions which generally occur in the presence of oxygen: 1) Singlet oxygen, produced
by dye sensitization due to the hydrolysis that reacts with thiourea to form oxidative products like urea and other sulfur-containing
fragments and 2) bleaching of dye, which leads to the reduction. The rate of reaction in all studied parameters followed first
order kinetics with respect to maximum absorption of the dye in the visible band region. Reaction kinetics was significantly
dependent upon the medium and the reaction accelerated more rapidly at low pH. A direct relation was exhibited between the
thiourea concentration and dye sensitizer, which was not pragmatic with the concentration of dye. The reaction was effected
by the temperature, and the values of energy parameters suggested that the energy of activation was low while the entropy
of activation increases with the rise in temperature, which indicated a highly solvated state of intermediate complex. Lower
value of ΔH* and ΔG* at elevated temperature showed that free energy is the driving force for the completion of reaction. A mechanism based on
the above findings has been suggested. 相似文献