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排序方式: 共有231条查询结果,搜索用时 31 毫秒
21.
Malek SN Lee GS Hong SL Yaacob H Wahab NA Faizal Weber JF Shah SA 《Molecules (Basel, Switzerland)》2011,16(6):4539-4548
Investigations on the cytotoxic effects of the crude methanol and fractionated extracts (hexane, ethyl acetate) C. mangga against six human cancer cell lines, namely the hormone-dependent breast cell line (MCF-7), nasopharyngeal epidermoid cell line (KB), lung cell line (A549), cervical cell line (Ca Ski), colon cell lines (HCT 116 and HT-29), and one non-cancer human fibroblast cell line (MRC-5) were conducted using an in-vitro neutral red cytotoxicity assay. The crude methanol and fractionated extracts (hexane and ethyl acetate) displayed good cytotoxic effects against MCF-7, KB, A549, Ca Ski and HT-29 cell lines, but exerted no damage on the MRC-5 line. Chemical investigation from the hexane and ethyl acetate fractions resulted in the isolation of seven pure compounds, namely (E)-labda-8(17),12-dien-15,16-dial (1), (E)-15,16-bisnor-labda-8(17),11-dien-13-on (2), zerumin A (3), β-sitosterol, curcumin, demethoxycurcumin and bis-demethoxycurcumin. Compounds 1 and 3 exhibited high cytotoxic effects against all six selected cancer cell lines, while compounds 2 showed no anti-proliferative activity on the tested cell lines. Compound 1 also demonstrated strong cytotoxicity against the normal cell line MRC-5. This paper reports for the first time the cytotoxic activities of C. mangga extracts on KB, A549, Ca Ski, HT-29 and MRC-5, and the occurrence of compound 2 and 3 in C. mangga. 相似文献
22.
In this paper, a new fuzzy linear programming (FLP)-based methodology using a specific membership function named modified logistic membership function is proposed. The modified logistic membership function is first formulated and its flexibility established by an analytical approach. This membership function is tested for its useful performance through an illustrative example by employing FLP. The developed methodology of FLP has provided confidence in applying to real-life industrial production planning problem. This approach of solving industrial production planning problem can provide feedback to the decision maker, implementer and analyst. In such cases, this approach can be called interactive FLP. There is a possibility to design the self-organizing of the fuzzy system for the product mix selection problem in order to find a satisfactory solution. The decision maker, analyst and implementer can incorporate their knowledge and experience to obtain the best outcome. 相似文献
23.
24.
Carbon‐doped titania (C‐TiO2) nanoparticles were synthesized by the sol–gel method at different calcination temperatures (300–600°C) employing titanium tetraisopropoxide (TTIP) as the titanium source and polyoxyethylene sorbitan monooleate (Tween 80) as the carbon source. The physical properties of C‐TiO2 samples were characterized by X‐ray diffraction (XRD) and scanning electron microscopy (SEM). The photocatalytic activities were checked through the photodegradation of phenolphthalein (PHP) under ultraviolet irradiation. The UV spectrum showed that the carbon doping extends the absorption range of TiO2 to the visible region. However, the photocatalytic activity is affected by the electron–hole recombination phenomenon, as revealed by the photoluminescence (PL) study. According to the PL spectra, carbon doping reduces the edge‐to‐edge electron–hole recombination. Nevertheless, the number of defect sites is greatly influenced by the calcination temperature of C‐TiO2. C‐TiO2 that was calcined at 400°C showed the highest photodegradation percentage of PHP, which was mainly attributed to the synergic effect of the low direct edge‐to‐edge electron–hole recombination, high content of defect sites, and retention of active electrons on the surface hydroxyl group. 相似文献
25.
Isahak Wan Nor Roslam Wan Hasan Siti Zubaidah Ramli Zatil Amali Che Ba-Abbad Muneer M. Yarmo Mohd Ambar 《Research on Chemical Intermediates》2019,45(3):951-953
Research on Chemical Intermediates - 相似文献
26.
Nor Aiyyuhal Jemali Hasan Abu Kassim V. Radhika Devi Keshav N. Shrivastava 《Journal of Non》2008,354(15-16):1744-1750
We have used the density functional theory to make the models of GexSe1?x glass for which the energy is a minimum. The clusters, Ge2Se2, Ge2Se3, Ge3Se, Ge3Se2, Ge4Se, GeSe3, GeSe4, chain mode zig-zag Ge4Se3, corner sharing GeSe4, and edge sharing Ge2Se6, have been made successfully and their vibrational spectra have been calculated from the first principles. We are able to optimize the bond distances as well as the bond angles. The calculated values of the frequencies of vibrations of the various clusters have been compared with those obtained from the experimental Raman spectra of actual glasses, GexSe1?x(0 < x < 0.3). The local concentration, x within 0.25 nm is nonuniform in the amorphous material. When the same cluster occurs in two stable configurations, low frequency vibrations of frequency, ν < 100 cm?1, are found. The corner sharing GeSe4 has low frequency modes at 54 cm?1 and 93 cm?1 whereas these modes disappear in the pyramidal configuration. The low frequency modes are therefore associated with the breaking of C4 symmetry of the pyramidal configuration. The computed vibrational frequencies of clusters Ge3, Ge4Se3, Ge2Se3, GeSe3 and Ge3Se2 are actually present in the Raman spectra of the glass, GexSe1?x(0 < x < 0.3). 相似文献
27.
Emad A. Jaffar Al-Mulla Nor Azowa Bt Ibrahim Kamyar Shameli Mansor Bin Ahmad Wan M. Zin Wan Yunus 《Research on Chemical Intermediates》2014,40(8):2887-2894
Hydrofluoric acid has been used as a stripping agent for molybdenum(VI) using a mixture of N,N’-carbonyl difatty amides (CDFAs) synthesized from palm oil as a extractant. The CDFAs was characterized by Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance technique. In the extraction step, the effects of parameters, such as type of diluent, hydrochloric acid, metal concentration, and temperature, have been studied. The effects of various stripping agents on stripping efficiency have also been investigated. This work presents the development of a low-cost and environmentally friendly extractant to recover molybdenum. 相似文献
28.
Wan Nor Roslam Wan Isahak Siti Zubaidah Hasan Zatil Amali Che Ramli Muneer M. Ba-Abbad Mohd Ambar Yarmo 《Research on Chemical Intermediates》2018,44(2):829-841
Mixed Cu and Mg oxides on nitrogen-rich activated carbon (AC) from Nypha fruticans biomass were characterized and their CO2 adsorption performance was measured. Highly dispersed CuO and MgO nanoparticles on AC was obtained using an ultrasonic-assisted impregnation method. The optimum adsorbent is 5%CuO–25%MgO/AC having good surface properties of high surface area, pores volume and low particles agglomeration. The higher content of MgO of 5%CuO–25%MgO/AC adsorbent contributes to less metal carbide formation which increases their porosity, surface area and surface basicity. XPS analysis showed some amount of nitrogen content on the surface of the adsorbent which increased their surface basicity towards selective CO2 adsorption. The presence of moisture accelerated the CO2 chemisorption to form a hydroxyl layer on the surfaces. The 5%CuO–25%MgO/AC adsorbent successfully adsorbed CO2 via physisorption and chemisorption of 14.8 and 36.2 wt%, respectively. It was significantly higher than fresh AC with better selectivity to CO2. 相似文献
29.
The adsorption of amino acids onto mineral surfaces plays an important role in a wide range of areas, e.g., low-temperature aqueous geochemistry, bone formation and protein-bone interactions. In this work, the adsorption of three alpha aminoacids (sarcosine, MIDA and EDDA) onto goethite (alpha-FeOOH) was studied as a function of pH and background electrolyte concentration at 25.0 degrees C, and the molecular structures of the surface complexes formed were analyzed by means of ATR-FTIR spectroscopy. The results showed that adsorption of alpha amino acids were strongly dependent on the functionality and structure of the ligands. No adsorption was detected for the zwitterionic sarcosine indicating that simple alpha amino acids without other ionizable and/or functional groups display insignificant affinity for mineral surfaces such as goethite. With respect to the more complex amino acids, which are surface reactive, the number and relative positions of carboxylate and amine groups determine the types of surface interactions. These interactions range from non-specific outer-sphere to specific inner-sphere interactions as shown by the MIDA and EDDA results, respectively. The results presented herein suggest that isomerically-selective adsorption might only occur for amino acids that are capable of specific surface interactions, either through site-specific hydrogen bonding or inner-sphere complexation. 相似文献
30.
I. A. Kirovskaya P. E. Nor T. L. Bukashkina E. V. Mironova 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2016,90(3):522-529
The physicochemical (acidic-basic, adsorption, and electrophysical) surface properties of binary semiconductor analogs of CdBVI (CdTe, CdSe, and CdS), and (CdTe)x(CdSe)1–x, and (CdTe)x(CdS)1–x solid substitution solutions were studied using modern methods and equipment. The nature of the active centers and the mechanisms of acidic-basic, adsorption (involving СО), and electronic interactions, interrelated tendencies in variation of the surface properties under study, and their correlations with the known bulk physicochemical properties were elucidated; the property–composition diagrams were constructed, which were used to reveal the most active adsorbents suggested for use as materials for СО (carbon monoxide) microimpurity sensors. 相似文献