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Chinese Physics Letters 2019年第10期36卷 32-35页

作者： H.Ahmad m.f.ismail S.N.Aidit Photonics Research Center University of MalayaKuala Lumpur 50603Malaysia Physics Department Faculty of ScienceUniversity of Malaya50603 Kuala LumpurMalaysia

A tunable and optically modulated fiber laser utilizing a multi-walled carbon nanotube based saturable absorber is demonstrated for operation in the O-band region.A praseodymium-doped fluoride fiber is used as the gain medium and the system is capable of generating modulated outputs at 1300 *** output is observed at pump powers of 511 mW and above,with repetition rates and pulse widths that can be tuned from 41 kHz and 3.4μs to 48 kHz and 2.4μs,respectively,at the maximum pump power available.A maximum average output power of 100μW with a corresponding single pulse energy of 2.1 nJ is measured,while the tunability of the proposed laser is from 1290 nm to 1308 *** output is stable,with peak power fluctuations of^4 dB from the average value.

关键词： pump fiber Optically

A Q-Switched Erbium-Doped fiber Laser with a Carbon Nanotube Based Saturable Absorber

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Chinese Physics Letters 2012年第11期29卷 67-69页

作者： S.W.Harun m.A.ismail f.Ahmad m.f.ismail R.m.Nor N.R.Zulkepely H.Ahmad Department of Electrical Engineering University of Malaya 50603 Kuala LumpurMalaysia Photonics Research Center Department of PhysicsUniversity of Malaya50603 Kuala LumpurMalaysia Department of Physics University of Malaya50603 Kuala LumpurMalaysia

We demonstrate a simple,compact and low cost Q-switched erbium-doped fiber laser(EDfL)using single-wall carbon nanotubes(CNTs)as a saturable absorber for possible applications in metrology,sensing,and medical *** EDfL operates at around 1560 nm with repetition rates of 16.1 kHz and 6.4 kHz with saturable absorbers SA1 and SA2 at a pump power of 120 *** absorbers are constructed by optically driven deposition and normal deposition *** is observed that the optical deposition method produces a Q-switched EDfL with a lower threshold of 70 mW and better Q-switching performance compared to that of the normal deposition *** EDfL also has pulse energy of 90.3 nJ and pulse width of 11.6μs at 120 mW pump power.

关键词： pump switched Erbium

Titanium dioxide-based Q-switched dual wavelength in the 1 micron region

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Chinese Optics Letters 2016年第9期14卷 48-52页

作者： H.Ahmad m.A.m.Salim Z.A.Ali m.f.ismail K.Thambiratnam A.A.Latif N.Nayan S.W.Harun Photonics Research Centre(PRC) University of Malaya Department of Physics University Putra Malaysia faculty of Electrical and Electronic Engineering Universiti Tun Hussein Onn Malaysia

In this work a passively Q-switched dual-wavelength ytterbium-doped fiber laser using a titanium dioxide-based saturable absorber is proposed and proven. The system also utilizes a side-polished fiber in a ring cavity configuration to obtain the desired pulse train. A stable dual-wavelength pulse output is obtained at 1034.7and 1039.0 nm, with a maximum pulse energy of 2.0 n J, and a shortest pulse width of 3.2 μs. The generated pulse train is stable, and has a pulse repetition rate from 31.2 to 64.5 kHz.

关键词： Titanium dioxide-based Q-switched dual wavelength in the 1 micron region

Electrical Conductivity and Sensitive Characteristics of Ag-Added BaTiO_3-CuO mixed Oxide for CO_2 Gas Sensing

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Journal of materials Science & Technology 2011年第1期27卷 35-40页

作者： A.m.El-Sayed f.m.ismail S.m.Yakout Inorganic Chemistry Department National Research CentreTahrir StreetDokki P.C.12622 CairoEgypt

Carbon dioxide gas sensors based on BaTiO3-CuO composite with different concentrations of Ag addition（1,1.5 and 2 wt%） have been prepared by stander ceramic method and sintered at 500 and 700℃ for 5 *** conductivity and gas sensing properties of the prepared samples were *** conductivity measurement was used to characterize the obtained sintered sensor *** was found that electrical conductivity and the sensitivity to CO2 were improved with Ag addition and *** correlation between Ag content at different sintering temperature and sensing characteristics towards CO2 is discussed.

关键词： BaTiO3-CuO composite Ag addition Electrical conductivity CO2 sensitive properties

Infrared, Diffuse Reflectance and Dielectric Studies ofAntimony Trisulphide

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Journal of materials Science & Technology 1998年第4期14卷 344-348页

作者： Hanafi, Z.m. ismail, f.m. Khalil, m.Sh. Inorganic Chemistry Dept. National Research Centre Dokki Cairo Egypt

Infrared absorption spectra of orange, black and transferred Sb//2S//3 samples have been studied in the spectral range 200-4000 cm** minus **1. The pronounced difference between the different samples is the appearance of excess sulphur present in the orange and transferred samples except those of transferred at 543 K and the black Sb//2S//3. The change of sharpness of some IR peaks reveals the amorphous/crystalline change. The effect of the degree of crystallinity and stoichiometry on the energy gap values was investigated by using optical method. The obtained dielectric parameters epsilon prime and epsilon double prime of the different samples are thoroughly affected by the degree of crystallinity and smoothly affected by either the frequency or the temperature or both, except at lower frequencies. (Edited author abstract) 26 Refs.

关键词： Antimony compounds

Spectral features and antibacterial properties of Cu-doped ZnO nanoparticles prepared by sol-gel method

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Chinese Physics B 2016年第7期25卷 459-465页

作者： Alireza Samavati A f ismail Hadi Nur Z Othaman m K mustafa Centre for Sustainable Nanomaterials Ibnu Sina Institute for Scientific and Industrial ResearchUniversiti Teknologi Malaysia Advanced membrane Technology Research Centre (AmTEC) Universiti Teknologi Malaysia faculty of Science Technology and Human Development Universiti Tun Hussein Onn Malaysia

Zn（1-x）Cux O（x=0.00, 0.01, 0.03, and 0.05） nanoparticles are synthesized via the sol-gel technique using gelatin and nitrate precursors. The impact of copper concentration on the structural, optical, and antibacterial properties of these nanoparticles is demonstrated. Powder x-ray diffraction investigations have illustrated the organized Cu doping into ZnO nanoparticles up to Cu concentration of 5%（x = 0.05）. However, the peak corresponding to CuO for x= 0.01 is not distinguishable. The images of field emission scanning electron microscopy demonstrate the existence of a nearly spherical shape with a size in the range of 30–52 nm. Doping Cu creates the Cu–O–Zn on the surface and results in a decrease in the crystallite size. Photoluminescence and absorption spectra display that doping Cu causes an increment in the energy band gap. The antibacterial activities of the nanoparticles are examined against Escherichia coli（Gram negative bacteria）cultures using optical density at 600 nm and a comparison of the size of inhibition zone diameter. It is found that both pure and doped ZnO nanoparticles indicate appropriate antibacterial activity which rises with Cu doping.

关键词： Cu-doped ZnO nanoparticles photoluminescence antibacterial E.coli

Antimonene-based saturable absorber for a soliton mode-locked and Q-switched fiber laser in the 2 μm wavelength region

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Chinese Physics B 2023年第6期32卷 259-269页

作者： H Ahmad B Nizamani m Z Samion N Yusoff m.f.ismail Photonics Research Centre Universiti Malaya50603 Kuala LumpurMalaysia Physics Department Faculty of ScienceUniversiti Malaya50603 Kuala LumpurMalaysia Distinguished Visiting Professor Universiti Kuala Lumpur British Malaysian Institute(UniKL BMI)Batu 8Jln Sungai Pusu53100SelangorMalaysia

We demonstrate antimonene as a saturable absorber(SA) to generate an ultrafast mode-locked and Q-switched laser in the 2 μm wavelength region. The two antimonene-based SAs were prepared and inserted separately in a thulium–holmiumdoped fiber laser to produce the pulsed laser. Antimonene was coated onto a tapered fiber to generate soliton mode-locked pulses and used in thin-film form for the generation of Q-switched pulses. The mode-locking was stable within a pump power of 267 m W–511 m W, and the laser operated at a central wavelength of 1897.4 nm. The mode-locked laser had a pulse width of 1.3 ps and a repetition rate of 12.6 mHz, with a signal-to-noise ratio of 64 d B. Q-switched laser operation was stable at a wavelength of 1890.1 nm within a pump power of 312 m W–381 m W. With the increase in pump power from 312 m W to 381 m W, the repetition rate increased to a maximum of 56.63 k Hz and the pulse width decreased to a minimum value of 2.85 μs. Wide-range tunability of the Q-switched laser was also realized within the wavelength range of1882 nm–1936 nm.

关键词： mode-locking Q-switched fiber laser optical saturable absorber

Antibacterial properties of copper-substituted cobalt ferrite nanoparticles synthesized by co-precipitation method

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Particuology 2017年第1期15卷 158-163页

作者： Alireza Samavati A. f. ismail Advanced membrane Technology Research Centre (AmTEC) Universiti Teknologi Malaysia 81310 Skudai Johor Malaysia

Controlled growth and careful characterization of cobalt ferrite nanoparticles for antibacterial applica- tions are challenging. Copper-substituted cobalt ferrite nanoparticles （CuxCo1-xfe2O4）, where x = 0.0, 0.3, 0.5, 0.7 and 1.0, were synthesized using an economical and simple co-precipitation technique. The crys- tal structure and antibacterial properties of the samples as a function of Cu-substituted content were systematically studied. With increasing Cu concentration, the nanopartide size decreased from ~30 to ~20 nm. The fourier transform infra-red spectra exhibit two prominent fundamental absorption bands, at ~595 and 419 cm^-1. These bands correspond to intrinsic stretching vibrations of metals at tetrahedral and octahedral sites, respectively. The Raman scattering results reveal that increasing the Cu content enhances the local disorder at both tetrahedral and octahedral sub lattices. The results indicate that the substitution of Co with Cu in cobalt ferrite nanoparticles strongly influences the microstructure, crystal structure, and oarticle diameter, and also improves the antibacterial properties.

关键词： Cobalt ferrite nanoparticles X-ray diffraction Raman spectroscopy Antibacterial properties

Advanced hydrogen storage of the mg–Na–Al system:A review

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Journal of magnesium and Alloys 2021年第4期9卷 1111-1123页

作者： N.A.Ali m.ismail Energy Storage Research Group Faculty of Ocean Engineering Technology and InformaticsUniversiti Malaysia Terengganu21030 Kuala NerusTerengganuMalaysia

A solid-state storage system is the most practical option for hydrogen because it is more convenient and *** hydrides,especially mgH_(2),are the most promising materials that offer high gravimetric capacity and good ***,the practical application of mgH_(2) is restricted by slow sorption kinetics and high stability of thermodynamic *** storage performance of mgH_(2) was enhanced by introducing the mg–Na–Al system that destabilises mgH_(2) with NaAlH_(4).The mg–Na–Al system has superior performance compared to that of unary mgH_(2) and NaAlH_(4).To boost the performance of the mg–Na–Al system,the ball milling method and the addition of a catalyst were *** mg–Na–Al system resulted in a low onset decomposition temperature,superior cyclability and enhanced kinetics *** Al_(12)mg_(17) and NamgH_(3) that formed in situ during the dehydrogenation process modify the reaction pathway of the mg–Na–Al system and alter the thermodynamic *** this paper,the overview of the recent progress in hydrogen storage of the mg–Na–Al system is *** remaining challenges and future development of mg–Na–Al system are also *** paper is the first review report on hydrogen storage properties of the mg–Na–Al system.

关键词： mg-Na-Al system mgH_(2) NaAlH_(4) Al_(12)mg_(17) hydrogen storage

Catalytic effect of SrTiO_3 on the hydrogen storage behaviour of mgH_2

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Journal of Energy Chemistry 2019年第1期28卷 46-53页

作者： m.S.Yahya m.ismail School of Ocean Engineering University Malaysia Terengganu

The effects of Sr TiO_3 on the hydrogen storage properties of mgH_2 have been studied for the first *** onset dehydrogenation temperature of the mgH_2-10 wt% SrTiO_3 is found to be 275 ℃, which is 55 ℃ lower as compared to the as-milled mgH_2. The composite is able to absorb 4.3 wt% of hydrogen in 60 min instead of 1.1 wt% for the as-milled mg H_2. meanwhile, the composite is able to release 5.3 wt% of hydrogen in 17 min compared to 1.9 wt% by the as-milled mg H_2 at 320 ℃. The calculated Eaof the mg H_2-10 wt% SrTiO_3 is 109 k J/mol, which is 26.3 kJ/mol lower than the calculated Eaof the as-milled mgH_2. The Sr TiO_3 is not decomposed during the ball milling and the re/dehydrogenation processes. The catalytic effect shown by the SrTiO_3 is owing to its ability to change the physical structure of the mgH_2 particles during the ball milling process.

关键词： Hydrogen storage magnesium hydride Catalytic effect Sorption properties