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排序方式: 共有393条查询结果,搜索用时 78 毫秒
141.
142.
Nazar Mohammad Ranjha Jahanzeb Mudassir Naveed Akhtar 《Journal of Sol-Gel Science and Technology》2008,47(1):23-30
In the present work methyl methacrylate-co-itaconic acid (MMA-co-IA) hydrogels were synthesized by free radical copolymerization
of methyl methacrylate (MMA) and itaconic acid (IA) using ethylene glycol dimethacrylate (EGDMA) and methylene bisacrylamide
(MBAAm) as crosslinkers and benzoyl peroxide as initiator. Selected samples were loaded with model drug lactulose. For the
lactulose release, the effect of pH, monomeric compositions, degree of crosslinking were investigated. The release of lactulose
was studied for 8 h period in USP phosphate buffer solutions of varying pH 1.2, 5.5, 6.5 and 7.0. The drug release data were
fitted into various kinetics models like the zero order, first order, Higuchi and Peppas. The release kinetics of lactulose
from MMA/IA hydrogels was found to be best described by the Peppas model. Results showed that drug release increased by increasing
IA content in the hydrogels but the effect of changing of crosslinking ratio on drug release was not significant. The surface
morphology of MMA/IA drug loaded hydrogel was studied by SEM which revealed uniform distribution of the drug in the hydrogels.
In conclusion, it can be said that lactulose can be successfully incorporated into crosslinked MMA/IA hydrogels and its release
can be modulated by changing the mole fraction of the acid component in the gels. 相似文献
143.
Muhammad N. Akhtar Muhammad Atiqullah Akhlaq A. Moman Atieh H. Abu‐Raqabah Neaz Ahmed 《大分子反应工程》2008,2(4):339-349
This study investigated the effects of several organotin silica surface modifiers on the ethylene polymerization performance of (nBuCp)2ZrCl2‐based supported catalysts in which MAO and metallocene were sequentially loaded. Each organotin compound acted as a spacer, increasing the catalyst activity. However, the catalyst activity and of the resulting polyethylenes varied as follows: Activity and fractional Sn+ charge: nBuSn(OH)2Cl > MeSnCl3 > nBuSnCl3 > Reference catalyst; and, : Reference catalyst > nBuSnCl3 > MeSnCl3 > nBuSn(OH)2Cl. The above catalyst activity rating was explained considering the influence of the Lewis acidity, that is, the fractional Sn+ charge of the organotin modifiers on the generation, concentration, and electron density at the active [(nBuCp)2ZrMe]+ cation. All the catalysts showed fairly stable kinetic profiles and produced narrow molecular weight distribution resins; 2.8 ≤ PDI ≤ 3.
144.
Nurul Fattin Che Rahim Yazmin Hussin Muhammad Nazirul Mubin Aziz Nurul Elyani Mohamad Swee Keong Yeap Mas Jaffri Masarudin Rasedee Abdullah Muhammad Nadeem Akhtar Noorjahan Banu Alitheen 《Molecules (Basel, Switzerland)》2021,26(5)
Colorectal cancer (CRC) is the third most common type of cancer worldwide and a leading cause of cancer death. According to the Malaysian National Cancer Registry Report 2012–2016, colorectal cancer was the second most common cancer in Malaysia after breast cancer. Recent treatments for colon cancer cases have caused side effects and recurrence in patients. One of the alternative ways to fight cancer is by using natural products. Curcumin is a compound of the rhizomes of Curcuma longa that possesses a broad range of pharmacological activities. Curcumin has been studied for decades but due to its low bioavailability, its usage as a therapeutic agent has been compromised. This has led to the development of a chemically synthesized curcuminoid analogue, (2E,6E)-2,6-bis(2,3-dimethoxybenzylidine) cyclohexanone (DMCH), to overcome the drawbacks. This study aims to examine the potential of DMCH for cytotoxicity, apoptosis induction, and activation of apoptosis-related proteins on the colon cancer cell lines HT29 and SW620. The cytotoxic activity of DMCH was evaluated using the [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] (MTT) cell viability assay on both of the cell lines, HT29 and SW620. To determine the mode of cell death, an acridine orange/propidium iodide (AO/PI) assay was conducted, followed by Annexin V/FITC, cell cycle analysis, and JC-1 assay using a flow cytometer. A proteome profiler angiogenesis assay was conducted to determine the protein expression. The inhibitory concentration (IC50) of DMCH in SW620 and HT29 was 7.50 ± 1.19 and 9.80 ± 0.55 µg/mL, respectively. The treated cells displayed morphological features characteristic of apoptosis. The flow cytometry analysis confirmed that DMCH induced apoptosis as shown by an increase in the sub-G0/G1 population and an increase in the early apoptosis and late apoptosis populations compared with untreated cells. A higher number of apoptotic cells were observed on treated SW620 cells as compared to HT29 cells. Human apoptosis proteome profiler analysis revealed upregulation of Bax and Bad proteins and downregulation of Livin proteins in both the HT29 and SW620 cell lines. Collectively, DMCH induced cell death via apoptosis, and the effect was more pronounced on SW620 metastatic colon cancer cells, suggesting its potential effects as an antimetastatic agent targeting colon cancer cells. 相似文献
145.
Perwez Alam Nasir Ali Siddiqui Md. Tabish Rehman Afzal Hussain Ali Akhtar Showkat R. Mir Mohamed Fahad Alajmi 《Molecules (Basel, Switzerland)》2021,26(7)
Parthenolide, a strong cytotoxic compound found in different parts of Tarchonanthus camphoratus which motivated the authors to develop an optimized microwave-assisted extraction (MEA) method using Box–Behnken design (BBD) for efficient extraction of parthenolide from the stem of T. camphoratus and its validation by high-performance thin-layer chromatography (HPTLC) and cytotoxic analysis. The optimized parameters for microwave extraction were determined as: 51.5 °C extraction temperature, 50.8 min extraction time, and 211 W microwave power. A quadratic polynomial model was found the most suitable model with R2 of 0.9989 and coefficient of variation (CV) of 0.2898%. The high values of adjusted R2 (0.9974), predicted R2 (0.9945), and signal-to-noise ratio (74.23) indicated a good correlation and adequate signal, respectively. HPTLC analyzed the parthenolide (Rf = 0.16) content in T. camphoratus methanol extract (TCME) at λmax = 575 nm and found it as 0.9273% ± 0.0487% w/w, which was a higher than expected yield (0.9157% w/w). The TCME exhibited good cytotoxicity against HepG2 and MCF-7 cell lines (IC50 = 30.87 and 35.41 µg/mL, respectively), which further supported our findings of high parthenolide content in TCME. This optimized MAE method can be further applied to efficiently extract parthenolide from marketed herbal supplements containing different Tarconanthus species. 相似文献
146.
We present a complete classification of locally rotationally symmetric (LRS) Bianchi-I space–times in accordance with their conformal Ricci collineations (CRCs). In the case where the Ricci tensor is nondegenerate, we find a general form of the vector field generating CRCs subject to some integrability conditions. Solving the integrability conditions in different cases, we find that the LRS Bianchi-I space–times admit 7-, 10-, 11-, or 15-dimensional Lie algebras of CRCs in the case where the Ricci tensor is nondegenerate. Moreover, we find that these space–times admit an infinite number of CRCs if the Ricci tensor is degenerate. We give some examples of LRS Bianchi-I space–times that admit nontrivial CRCs and are models of a perfect fluid. 相似文献
147.
Yugender Goud K. Hayat Akhtar Satyanarayana M. Sunil Kumar V. Catanante Gaëlle Vengatajalabathy Gobi K. Marty Jean Louis 《Mikrochimica acta》2017,184(11):4401-4408
Microchimica Acta - A versatile and cost-effective aptamer-based fluorescence quenching assay is described for the detection of the mycotoxin zearalenone (ZEN). Exfoliated functional graphene oxide... 相似文献
148.
A novel inorganic–organic composite solid electrolyte is prepared by using TiO2 nanotubes (TiNTs) as filler in polyethylene glycol (PEG) and effectively used for the fabrication of solid-state dye-sensitized solar cells (DSSCs). Comparably high conversion efficiency 4.43% has been observed by using the newly designed inorganic–organic (PEG–TiNTs) composite solid electrolyte. By performing several experiments by using PEG–TiNTs composite solid electrolytes, it was observed that the appropriate ratios of TiNTs and PEG are important to obtain higher conversion efficiency. Moreover, the morphologies, chemical interactions of PEG and TiNTs and their performance to the DSSCs are studied extensively by FESEM, DSC, and XPS measurements. 相似文献
149.
Naveed Akhtar Shad Muhammad Munir Sajid Yasir Javed Nasir Amin Muhammad Ikram Kanwal Akhtar Gulzar Ahmad Faisal Ali Aamir Razaq 《中国化学会会志》2020,67(6):1045-1053
Zinc oxide (ZnO) nanostructures were synthesized via a one-step solid-state reaction approach in ammonia (NH3) gas environment with different temperature ramp rates. The so-formed nanostructures were characterized using X-ray diffraction (XRD) for phase identification, where the typical wurtzite hexagonal structure was observed. Scanning electron microscopy (SEM) confirmed the particle size to be in the range 45–50 nm, the same as calculated by the XRD pattern for the ramp rate of 10 °C/min. Energy dispersive X-ray (EDX) spectroscopy and X-ray photoelectron spectroscopy (XPS) confirmed the chemical purity of the samples. The photoluminescence (PL) spectrum indicated multiple near-band-edge emissions and energy-band emissions. Then, these ZnO nanomaterials were used for the degradation of crystal violet (CV) dye under UV light irradiation. The CV solution was completely degraded in 2 hr. The initial photocatalyst and dye amounts of 0.2 g/100 ml and 0.5 mg/L, respectively, were found to be the optimum values for maximum degradation efficiency. The ZnO-based photocatalyst was stable up to three cycles of reuse. These results indicate that the high surface area and porosity of the nanomaterials are responsible for the high efficiency, which was confirmed by specific surface area analysis. 相似文献
150.
Akhtar J Afzaal M Vincent MA Burton NA Hillier IH O'Brien P 《Chemical communications (Cambridge, England)》2011,47(7):1991-1993
The low temperature growth of crystalline PbS films has been achieved on plastic substrates by CVD using a xanthate. The possible mechanism involved in this low temperature deposition has been probed by density functional theory calculations. 相似文献