排序方式: 共有59条查询结果,搜索用时 31 毫秒
51.
K.Khairi H.Fong Kok Z.Lambak M.I.Abdan M.A.Farhan M.H.Othman M.L.H.Jamaluddin S.A.Mohamad Rofie Tee Din Chai K.Chia Ching A.Mohd.Ramli M.A.Mokhtar S.A.Syed Ahmad M.Mokhtar S.B.Ahmad Anas M.A.Mahdi 《中国光学快报(英文版)》2018,(4)
We experimentally designed dispersion-managed repeaterless transmission systems with a pre-compensation and post-compensation technique using multi-channel-chirped fiber Bragg gratings. The repeaterless transmission link supports a single channel(1548.51 nm) with a 10 Gbps repeaterless transmission system over 300 km standard single-mode fiber(SSMF). In the system design, two distributed Raman amplifiers(DRAs) were used to improve the signal level propagated along the 300 km SSMF. The co-propagating DRA provided 15 dB on–off gain and the counter-propagating produced 32 dB on–off gain at the signal wavelength. The experiment results show that the post-compensation configuration achieves an optimal performance with a bit error rate at 1 × 10~(-9). 相似文献
52.
Sepideh Parvizpour Jafar Razmara Aizi Nor Mazila Ramli Rosli Md Illias Mohd Shahir Shamsir 《Journal of computer-aided molecular design》2014,28(6):685-698
The structure of a novel psychrophilic β-mannanase enzyme from Glaciozyma antarctica PI12 yeast has been modelled and analysed in detail. To our knowledge, this is the first attempt to model a psychrophilic β-mannanase from yeast. To this end, a 3D structure of the enzyme was first predicted using a threading method because of the low sequence identity (<30 %) using MODELLER9v12 and simulated using GROMACS at varying low temperatures for structure refinement. Comparisons with mesophilic and thermophilic mannanases revealed that the psychrophilic mannanase contains longer loops and shorter helices, increases in the number of aromatic and hydrophobic residues, reductions in the number of hydrogen bonds and salt bridges and numerous amino acid substitutions on the surface that increased the flexibility and its efficiency for catalytic reactions at low temperatures. 相似文献
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Medium pressure liquid chromatography and semipreparative high-performance liquid chromatography, followed by recycling high-performance liquid chromatography, were used for the isolation and purification of oligostilbenes from the acetone extracts of Dipterocarpus semivestitus and Neobalanocarpus heimii. Two stilbene dimers, ε-viniferin and cis-ε-viniferin, and a stilbene trimer, cis-miyabenol C were isolated from D. semivestitus. A trimer, ampelopsin C, and two tetramers, hemsleyanol D and isohopeaphenol, were isolated from N. heimii. The purities of the compounds were determined by an ultrahigh-performance liquid chromatography. 相似文献
55.
Hamman Tukur Gabdo Ahmad Termizi Ramli Nuraddeen Nasiru Garba Mohamad Sanusi 《Isotopes in environmental and health studies》2016,52(3):298-308
This study was aimed at providing the baseline data of terrestrial gamma dose rates and natural radioactivity to assess the corresponding health risk in the ambient environment of the Pahang State. Terrestrial gamma radiation (TGR) from 640 locations was measured with the mean value found to be 176?±?5 nGy h?1. Ninety-eight soil samples were analysed using a high-purity germanium detector (HPGe), and the mean concentrations of the radionuclides 226Ra, 232Th and 40K are 110?±?3, 151?±?5 and 542?±?51 Bq kg?1, respectively.226Ra and 232Th concentrations were found to be three times the world average, while that of 40K is quite higher than the world average value. The acid-intrusive geological formation has the highest mean concentrations for 226Ra (215?±?6 Bq kg?1), 232Th (384?±?12 Bq kg?1) and 40K (1564?±?153 Bq kg?1). The radium equivalent activities (Req) and the external hazard index (Hex) for the various soil types were also calculated. Some of the soil types were found to have values exceeding the internationally recommended levels of 370 Bq kg?1 and the unity value, respectively. 相似文献
56.
K. Adardour R. Touir Y. Ramli R. A. Belakhmima M. Ebn Touhami C. Kalonji Mubengayi H. El Kafsaoui E. M. Essassi 《Research on Chemical Intermediates》2013,39(4):1843-1855
7-Cchloro-3-(4-methoxystyryl)quinoxalin-2(1H)-one (CMOSQ) and 7-chloro-2-(4-methoxyphenyl)thieno(3.2-b)quinoxaline (CMOPTQ) have been investigated for mild steel corrosion in 1 M HCl at different concentrations using weight loss measurements, potentiodynamic polarization curves and electrochemical impedance spectroscopy methods. Generally, inhibition efficiency of the investigated compounds was found to depend on inhibitor concentration and their structures. Comparitive results showed that CMOPTQ was the best inhibitor and the inhibition efficiency increased with increasing the concentration and attained 86 and 87 % at 10?3 M of CMOPTQ and 10?3 M of CMOSQ, respectively. Potentiodynamic polarization studies clearly reveal that these inhibitors act essentially as cathodic-type inhibitors. The inhibition efficiency increases with immersion time and reaches 95 % CMOPTQ at 24 h. The electrochemical impedance spectroscopy result showed that these compounds act by formation of film. 相似文献
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A. T. Abdul Rahman A. T. Ramli 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(3):653-657
A survey was carried out to determine terrestrial gammaradiation dose rates, the concentration level of 238U and 232Th and α and β activities for the surface soil in Ulu Tiram, Malaysia A 125 measurements were performed using a NaI(T1) gamma-ray
detector with crystal size of 1″ × 1″ on 15 soil samples collected from the site area about 102 km2
238U and 232Th concentrations were determined in soils by using hyper pure germanium (HPGe) gamma-ray spectrometry. The activity of α
and β from the surface soil was counted by using alpha beta counting system. The average value of 238U and 232Th concentrations in soil samples collected are 3.63±0.39 ppm within the range of 1.74±0.20 to 4.58±0.48 and 43.00±2.31 ppm
within the range of 10.68±0.76 to 82 10±4.01 ppm, respectively. The average estimate of α and β activity in soil samples collected
are 0.65±0.09 Bqg−1 and 0.68±0.08 Bqg−1, respectively. The average of terrestrial gamma-radiation dose rates measured in Ulu Tiram was found to be 200 nGy h−1, within the range of 96 to 409 nGy h−1. The population weighted outdoor annual effective dose was 1.2 mSv. 相似文献
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Chun Yik Wong Kee Shyuan Loh Wan Ramli Wan Daud Kean Long Lim Mohammad Khalid 《高分子科学杂志,C辑:聚合物评论》2020,60(1):171-202
AbstractPoly(vinyl alcohol) (PVA) is a biodegradable, water-soluble membrane that has low methanol permeation and reactive chemical functionalities. Modification of these features makes PVA an attractive proton exchange membrane (PEM) alternative to NafionTM. However, the pristine PVA membrane is a poorer proton conductor than the NafionTM membrane due to the absence of negatively charged ions. Hence, modification of PVA matrixes whilst complying with the requirements of projected applications has been examined extensively. Generally, three modification methods of PVA membranes have been highlighted in previous reports, and these are (1) grafting copolymerization, (2) physical and chemical crosslinking, and (3) blending of polymers. The use of each modification method in different applications is reviewed in this study. Although the three modification methods can improve PVA membranes, the mixed method of modification provides another attractive approach. This review covers recent studies on PVA-based PEM in different fuel cell applications, including (1) proton-exchange membrane fuel cells and (2) direct-methanol fuel cells. The challenges involved in the use of PVA-based PEM are also presented, and several approaches are proposed for further study. 相似文献