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111.
Kian-Kai Cheng Muhammad Helmi Nadri Nor Zalina Othman Siti Nor Azlina Abd Rashid Ying-Chin Lim Hong-Yeng Leong 《Molecules (Basel, Switzerland)》2022,27(11)
Michelia × alba (M. alba) is a flowering tree best known for its essential oil, which has long been used as a fragrance ingredient for perfume and cosmetics. In addition, the plant has been used in traditional medicine in Asia and dates back hundreds of years. To date, there is a limited number of publications on the bioactivities of M. alba, which focused on its tyrosinase inhibition, antimicrobial, antidiabetic, anti-inflammatory, and antioxidant activities. Nevertheless, M. alba may have additional unexplored bioactivities associated with its bioactive compounds such as linalool (72.8% in flower oil and 80.1% in leaf oil), α-terpineol (6.04% flower oil), phenylethyl alcohol (2.58% flower oil), β-pinene (2.39% flower oil), and geraniol (1.23% flower oil). Notably, these compounds have previously been reported to exhibit therapeutic activities such as anti-cancer, anti-inflammation, anti-depression, anti-ulcer, anti-hypertriglyceridemia, and anti-hypertensive activities. In this review paper, we examine and discuss the scientific evidence on the phytochemistry, bioactivities, and traditional uses of M. alba. Here, we report a total of 168 M. alba biological compounds and highlight the therapeutic potential of its key bioactive compounds. This review may provide insights into the therapeutic potential of M. alba and its biologically active components for the prevention and treatment of diseases and management of human health and wellness. 相似文献
112.
Navzer D. Sachinvala David L. Winsor Othman Hamed Walter P. Niemczura Karol Maskos Tyrone L. Vigo Noelie R. Bertoniere 《先进技术聚合物》2002,13(6):413-427
Cellulose ( 1 ) was converted for the first time to 6‐phenyl‐6‐deoxy‐2,3‐di‐O‐methylcellulose ( 6 ) in 33% overall yield. Intermediates in the five‐step conversion of 1 to 6 were: 6‐O‐tritylcellulose ( 2 ), 6‐O‐trityl‐2,3‐di‐O‐methylcellulose ( 3 ), 2,3‐di‐O‐methylcellulose ( 4 ); and 6‐bromo‐6‐deoxy‐2,3‐di‐O‐methylcellulose ( 5 ). Elemental and quantitative carbon‐13 analyses were concurrently used to verify and confirm the degrees of substitution in each new polymer. Gel permeation chromotography (GPC) data were generated to monitor the changes in molecular weight (DPw) as the synthesis progressed, and the compound average decrease in cellulose DPw was ~ 27%. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to characterize the decomposition of all polymers. The degradation temperatures ( °C) and percent char at 500 °C of cellulose derivatives 2 to 6 were 308.6 and 6.3%, 227.6 °C and 9.7%, 273.9 °C and 30.2%, 200.4 °C and 25.6%, and 207.2 °C and 27.0%, respectively. The glass transition temperature (Tg) of6‐O‐tritylcellulose by dynamic mechanical analysis (DMA) occurred at 126.7 °C and the modulus (E′, Pa) dropped 8.9 fold in the transition from ?150 °C to + 180 °C (6.6 × 109 to 7.4 × 108 Pa). Modulus at 20 °C was 3.26 × 109 Pa. Complete proton and carbon‐13 chemical shift assignments of the repeating unit of the title polymer were made by a combination of the HMQC and COSY NMR methods. Ultimate non‐destructive proof of carbon–carbon bond formation at C6 of the anhydroglucose moiety was established by generating correlations between resonances of CH26 (anhydroglucose) and C1′, H2′, and H6′ of the attached aryl ring using the heteronuclear multiple‐bond correlation (HMBC) method. In this study, we achieved three major objectives: (a) new methodologies for the chemical modification of cellulose were developed; (b) new cellulose derivatives were designed, prepared and characterized; (c) unequivocal structural proof for carbon–carbon bond formation with cellulose was derived non‐destructively by use of one‐ and two‐dimensional NMR methods. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
113.
A model has been formulated for the prediction of average saturation and the saturation profile through a fibrous bed during coalescence of secondary dispersion. The approach utilizes the Blake-Kozeny equation to relate experimental pressure drop data to saturation in the bed. Reasonable agreement was obtained between predicted saturations and those measured experimentally. The predicted saturation profiles could be used to determine other coalescer design parameters. 相似文献
114.
Abdelhameed M. Othman 《Journal of Analytical Chemistry》2010,65(11):1191-1197
A new plasticized membrane sensor has been proposed for the determination of periodate based on periodate-cetylpyridinium
ion pair complex. The electrode shows a linear, reproducible and stable potentiometric response with anionic Nernstian slope
of 58.1 ± 0.5 mV/decade over a wide range of concentrations 10−5–10−2 M and a detection limit of 2.0 × 10−6 M of IO4−. The membrane exhibits a fast response time of 30–40 s which is independent of pH in the range 2.0–9.0. The selectivity coefficients
indicate excellent selectivity for periodate over a large number of anions, e.g. iodide, bromide, chloride, iodate, bromate,
nitrate, sulfate, phosphate, thiocyanate, chromate, thiosulfate, sulfite, perchlorate, citrate, acetate, oxalate, and nitrate.
The prepared sensor has been successfully used for the determination of periodate (IO4−) and iodate (IO3−) ions with an average recovery of 99.84 ± 0.34% and 98.22 ± 0.43%, respectively. It is also applied to the determination
of hydrazine compounds and aminophenol derivatives with an average recovery of 98.66 ± 0.53% and 98.40 ± 0.56%, respectively.
Also, the proposed sensor was used for the determination of potassium iodate in iodized table salt and hydrazine in steam
boiler feed water and p-aminophenol. The results obtained are in good agreement with those obtained by standard methods. 相似文献
115.
Nicolas Droushiotis Mohd Hafiz Dzarfan Othman Uttam Doraswami Zhentao Wu Geoff Kelsall Kang Li 《Electrochemistry communications》2009,11(9):1799-1802
Novel CGO/NiO–CGO dual-layer hollow fibres (HFs) have been fabricated in a single-step co-extrusion and co-sintering process. LSCF–CGO cathodes layers were then deposited onto the dual-layer HFs to construct micro-tubular SOFCs. The NiO in the micro-tubular HF–SOFCs was reduced at 550 °C using hydrogen gas to form Ni anodes. Scanning electron microscope images showed that the dual-layer HFs have porous anodes and dense electrolyte layers. Preliminary measurements with a HF–SOFC fed with H2 and atmospheric oxygen, produced maximum power densities of 420 W m−2 and 800 W m−2 at 450 °C and 550 °C, respectively. 相似文献
116.
The propagation of plane waves in fibre-reinforced, rotating thermoelastic half-space proposed by Lord-Shulman is discussed.
The problem has been solved numerically using a finite element method. Numerical results for the temperature distribution,
the displacement components and the thermal stress are given and illustrated graphically. Comparisons are made with the results
predicted by the coupled theory and the theory of generalized thermoelasticity with one relaxation time in the presence and
absence of rotation and reinforcement. It is found that the rotation has a significant effect and the reinforcement has great
effect on the distribution of field quantities when the rotation is considered. 相似文献
117.
Calculation of electric field–temperature (E,T) phase diagram of a ferroelectric liquid crystal near the SmA–SmC_α~* transition 下载免费PDF全文
In this work we perform a theoretical calculation in order to reconstitute the(E–T) phase diagram of a chiral smectic liquid crystal in the vicinity of the SmA–SmC_α~* transition. This reconstruction is carried out on the basis of a thermodynamic calculation of the slope of the curve joining the SmC_α~* domain and the unwound SmC~*. An empiric correction of the mean field term of Landau De-Gennes development is necessary to accomplish this reconstruction. Thereafter, an experimental validation is performed to verify our calculations. 相似文献
118.
119.
A new, simple method to obtain ultrathin polycationic monolayers on hydroxylated surfaces is described which uses a bifunctional copolymer comprising a reactive part (trimethoxysilane) and positive charges (quaternary ammonium salts) to confer antimicrobial properties. 相似文献
120.
Microscopic magnetic resonance elastography is a high-resolution method for visualizing shear waves and assessing the biomechanical viscoelastic properties of small biological samples. In this work, we used error propagation to develop a simple analytical model that relates the signal-to-noise ratio of MR magnitude images to the variance in shear-wave maps collected using gradient-echo and spin-echo phase-contrast pulse sequences. Our model predicts results for shear-wave images in phantoms, which match the experimentally observed phase variance within 8%. This model can be used to optimize MR pulse sequences for elastography studies, as well as other phase-difference techniques in MRI. 相似文献