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Femtosecond laser induced nanostructuring of zirconium in liquid confined environment

Chinese Physics B 2017年第1期26卷 310-319页

作者： Nisar Ali Shazia Bashir Umm-i-Kalsoom m.shahid rafique Narjis Begum Wolfgang Husinsky Ali Ajami Chandra S.R.Natahala Laser Laboratories Institute for Applied Physics Vienna University of Technology 1040 Vienna Austria Department of Basic Sciences and Humanities University of Engineering and Technology Lahore Faisalabad Campus Faisalabad Pakistan Laser Laboratories Centre for Advanced Studies m Physics GC University 1-Church Road Lahore Pakistan Department of Physics GC University Kachehri Road Lahore Pakistan Department of Physics Riphah International University Islamahad (Lahore Campus) Lahore Pakistan Department of Physics University of Engineering and Technology Lahore Pakistan Department of Physics COMSATS Institute of Information Technology Islamabad Pakistan

The surface, structural, and mechanical properties of zirconium after irradiation with Ti： sapphire laser（800 nm, 30 fs,1 k Hz） have been investigated. The zirconium targets were exposed for a varying number of laser pulses ranging from 500 to 2000 at a fixed fluence of 3.6 J/cm^2 corresponding to an intensity of 1.2×10^14W/cm^2 in ambient environments of deionized water and propanol. A scanning electron microscope（SEm） was employed to investigate the surface morphology of the irradiated zirconium. The SEm analysis shows the formation of various kinds of features including nanoscale laser induced periodic surface structures（LIPSS）, sponge like surface structure, flakes, conical structures, droplets, pores, and cavities. The energy dispersive x-ray spectroscopy（EDS） analysis exhibits the variation in chemical composition along with an enhanced diffusion of oxygen under both ambient conditions. The crystal structure and phase analyses of the exposed targets were explored by x-ray diffraction（XRD） and Raman spectroscopy techniques, respectively. The XRD analysis confirms the presence of various phases of zirconium hydride and zirconia after ablation in both de-ionized water and propanol. However, excessive hydrides are formed in the case of propanol. The Raman analysis supports the EDS and XRD results. It also reveals the presence of oxides（zirconia） after irradiation in both de-ionized water and propanol *** chemical reactivity of zirconium was significantly improved in the presence of liquids which were accountable for the growth of novel phases and modification in the chemical composition of the irradiated Zr. A nanohardness tester was employed to measure the nanohardness of the laser treated targets. The initial increase and then decrease in nanohardness was observed with an increase in the number of laser pulses in the de-ionized water environment. In the case of propanol,a continuous decrease in hardness was observed.

关键词： ambient environments periodic structure crystallinity synthesis

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Competing crystallite size and zinc concentration in silica coated cobalt ferrite nanoparticles

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Progress in Natural Science:materials International 2014年第3期24卷 199-204页

作者： K.Nadeem m.shahid m.mumtaz materials Research Laboratory Department of Physics International Islamic University

Silica coated(30 wt%) cobalt zinc ferrite(Co1 xZnxFe2O4, x?0, 0.2, 0.3, 0.4, 0.5 and 1) nanoparticles were synthesized by using sol–gel method. Silica acts as a spacer among the nanoparticles to avoid the agglomeration. X-ray diffraction(XRD) reveals the cubic spinel ferrite structure of nanoparticles with crystallite size in the range 37–45 nm. Fourier transform infrared(FTIR) spectroscopy confirmed the formation of spinel ferrite and SiO2. Scanning electron microscopy(SEm) images show that the nanoparticles are nearly spherical and non-agglomerated due to presence of non-magnetic SiO2 surface coating. All these measurements signify that the structural and magnetic properties of Co1 xZnxFe2O4 ferrite nanoparticles strongly depend on Zn concentration and nanoparticle average crystallite size in different Zn concentration regimes.& 2014 Chinese materials Research Society. Production and hosting by Elsevier B.V. All rights reserved.

关键词： Ferrite Nanoparticles Composites magnetic properties

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Floating Solid Particles Interacting with Tilted Square Obstacles in Fluid Affecting Drag Forces

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Advances in Applied mathematics and mechanics 2023年第2期15卷 359-375页

作者： K.Usman S.Jabeen m.shahid Department of mathematics Air UniversityPAF ComplexIslamabad 44000Pakistan

We have analyzed the kinetics of solid circular particles interacting with fluid,outer boundary and internal square shaped obstacles tilted at a 45°*** effects on the motion of particle due to collision with obstacles and wall are *** Eulerian approach is used to study the behavior of particle in the fixed computational *** interactions between fluid,particles and obstacles have been carried out in the whole domain by using fictitious boundary method(FBm).In this work,the particulate flow simulations are computed by using finite element solver *** results are presented by assigning different alignments to the obstacles and varying their positions in the ***-wall,particle-particle and particleobstacle collisions are treated by applying a modified collision model proposed by Glowinski et *** rapid change in drag forces acting on obstacles due to nearby passing particles and its effect on the fluid motion has been investigated.

关键词： Particulate flow direct numerical simulation fictitious boundary method finite element method multigrid sedimentation

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Weathering and accumulation of trace elements in the soils of the Porali Plain, Balochistan: repercussions in agriculture

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Acta Geochimica 2024年第2期43卷 214-234页

作者： maria Kaleem Erum Bashir shahid Naseem Tahir rafique Bushra Shahab Department of Geology University of KarachiKarachi 75270Pakistan Applied Chemistry Research Centre PCSIR Laboratories ComplexKarachi 75280Pakistan

This study is theﬁrst attempt to assess the nature of the soil,especially on the western side of the Porali Plain in Balochistan;a new emerging agriculture hub,using weathering and pollution indices supplemented by multi-variate analysis based on geochemical *** outcomes of this study are expected to help farmers in soil manage-ment and selecting suitable crops for the ***-ﬁve soil samples were collected,mainly from the arable land of the Porali *** drying and coning-quarter-ing,soil samples were analyzed for major and trace ele-ments using the XRF technique;sieving and hydrometric methods were employed for granulometric ***-mated data were analyzed using Excel,SPSS,and Surfer software to calculate various indices,correlation matrix,and spatial *** granulometric analysis showed that 76%of the samples belonged to loam types of soil,12%to sand type,and 8%to silt *** indices:CIA,CIW,PIA,PWI,WIP,CIX,and ICV were calculated to infer the level of *** indices reﬂect mod-erate to intense weathering;supported by K_(2)O/AI_(2)O_(3),Rb/K_(2)O,Rb/Ti,and Rb/Sr *** of the geo-ac-cumulation and Nemerow Pollution indices pinpoint rela-tively high concentrations of Pb,Ni,and Cr concentration in the *** correlation matrix and Principal Compo-nent Analysis show that the soil in this study area is mainly derived from the weathering of igneous rocks of Bela Ophiolite(Cretaceous age)and Jurassic sedimentary rocks of mor Range having SEDEX/mVT type *** may result in the undesirable accumulation of certain trace elements which adversely affects crops.

关键词： Weathering indices Pollution indices Accumulation Repercussions Trace elements multivariate analyses Porali Plain Balochistan

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Effect of Cumulative Nanosecond Laser Pulses on the Plasma Emission Intensity and Surface morphology of Pt-and Ag-Ion Deposited Silicon

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Plasma Science and Technology 2012年第4期14卷 333-337页

作者： Khurram SIRAJ muhammad Zakria BUTT muhammad KHALEEQ-UR-RAHmAN muhammad shahid rafique Saima rafique FAKHAR-UN-NISA Advanced Physics Laboratory Department of PhysicsUniversity of Engineering and Technology

In this work, the laser induced plasma plume characteristics and surface morphology of Pt- and Ag-ion deposited silicon were studied. The deposited silicon was exposed to cumulative laser pulses. The plasma plume images produced by each laser shot were captured through a computer controlled image capturing system and analyzed with image-J software. The integrated optical emission intensity of both samples showed an increasing trend with increasing pulses. Agion deposited silicon showed higher optical emission intensity as compared to Pt-ion deposited silicon, suggesting that more damage occurred to the silicon by Ag ions, which was confirmed by SRIm/TRIm simulations. The surface morphologies of both samples were examined by optical microscope showing thermal, exfoliational and hydrodynamical sputtering processes along with the re-deposition of the material, debris and heat affected zones＇ formation. The crater of Ption deposited silicon was deeper but had less lateral damage than Agion deposited silicon. The novel results clearly indicated that the ion deposited silicon surface produced incubation centers, which led to more absorption of incident light resulting into a higher emission intensity from the plasma plume and deeper crater formation as compared to pure silicon. The approach can be effectively utilized in the laser induced breakdown spectroscopy technique, which endures poor limits of detection.

关键词： ions deposited silicon laser irradiation plasma plume emission intensity,crater formation

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Effect of fluence and ambient environment on the surface and structural modification of femtosecond laser irradiated Ti

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Chinese Physics B 2016年第1期25卷 789-795页

作者： Umm-i-Kalsoom Shazia Bashir Nisar Ali m.shahid rafique Wolfgang Husinsky Chandra S R Nathala Sergey V makarov Narjis Begum Institute for Applied Physics Vienna University of TechnologyViennaAustria Centre for Advanced Studies in Physics GC University LahorePakistan Department of Physics The University of LahorePala'stan Department of Basic Sciences and Humanities University of Engineering and Technology FasalabadPakistan Department of Physics University of Engineering and Technology LahorePakistan P.N.Lebedev Physics Institute RAS MoscowRussia Department of Physics COMSATS Institute of Information and TechnologyIslamabadPakistan

Under certain conditions, ultrafast pulsed laser interaction with matter leads to the formation of self-organized conical as well as periodic surface structures （commonly reffered to as, laser induced periodic surface structures, LIPSS）. The purpose of the present investigations is to explore the effect of fsec laser fluence and ambient environments （Vacuum ＆ 02） on the formation of LIPSS and conical structures on the Ti surface. The surface morphology was investigated by scanning electron microscope （SEm）. The ablation threshold with single and multiple （N = 100） shots and the existence of an incubation effect was demonstrated by SEm investigations for both the vacuum and the 02 environment. The phase analysis and chemical composition of the exposed targets were performed by x-ray diffraction （XRD） and energy dispersive x-ray spectroscopy （EDS）, respectively. SEm investigations reveal the formation of LIPSS （nano ＆ micro）. FFT d-spacing calculations illustrate the dependence of periodicity on the fluence and ambient environment. The periodicity of nano-scale LIPSS is higher in the case of irradiation under vacuum conditions as compared to 02. Furthermore, the 02 environment reduces the ablation threshold. XRD data reveal that for the 02 environment, new phases （oxides of Ti） are formed. EDS analysis exhibits that after irradiation under vacuum conditions, the percentage of impurity element （A1） is reduced. The irradiation in the 02 environment results in 15% atomic diffusion of oxygen.

关键词： LIPSS ablation threshold incubation coefficient structural modification

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Antibacterial Action of Chemically Synthesized and Laser Generated Silver Nanoparticles against Human Pathogenic Bacteria

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Journal of materials Science & Technology 2016年第8期32卷 721-728页

作者： Nosheen Zafar Shahzadi Shamaila Jawad Nazir Rehana Sharif muhammad shahid rafique Jalees Ul-Hasan Syeda Ammara Hina Khalid Department of Physics University of Engineering and Technology Lahore 54890 Pakistan Department of microbiology University of Veterinary and Animal Sciences Lahore Pakistan Department of Physics Forman Christian College A Charted University Lahore Pakistan

Silver nanoparticles in the range of 10-40 nm were synthesized chemically and by laser ablation, em- ployed for in vitro antibacterial action against human pathogenic bacterium. Their formation was evidenced by UV-visible spectrophotometer; particle size confirmed by atomic force microscopy, crystal structure determined by X-ray diffraction and chemical composition investigated by Fourier transform infrared spec- troscopy. The calculated mIC （minimum inhibitory concentration） of chemically synthesized nanoparticles with 30-40 nm in size are 2.8 μg/mL 4.37 μg/mL 13.5μg/mL and 2.81 p.g/mL for E. coil, S. aureus, B. subtillis and Salmonella, respectively. Whereas laser ablated nanoparticles exhibit mIC of 2.10 μg/mL 2.36 μg/ mL and 2.68 μg/mL for E. coli, S. aureus and Salmonella, respectively.

关键词： Chemically synthesized and laser ablated nanoparticles UV-visible spectrophotometer Gram negative and gram positive bacteria

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On the roads to H1N1 pandemic era:drive safe and fearless using colour-coded masks

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Asian Pacific Journal of Tropical medicine 2012年第4期5卷 333-334页

作者： m.shahid Department of microbiology Immunology & Infectious DiseasesCollege of Medicine & Medical SciencesArabian Gulf UniversityKingdom of Bahrain Section of Antimicrobial Resistance Research and molecular Biology Department of MicrobiologyJawaharlal Nehru Medical College & HospitalAligarh Muslim UniversityAligarh-202002Uttar PradeshIndia

Notwithstanding the end of 2009 H1N1 pandemic,the threat for its revisit still persists and WHO has warned to remain *** that lime the situation was more panicky than *** this article,a suggestion to minimize the panic is provided by the usage of colour-coded masks and is proposed hereby as a "population segregation" approach in case of the revisit of HlNl or similar threatening respiratory viral infections.

关键词： H1N1 Respiratory viral infections Colour-coded masks Population segregation Public health

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Characterization of ion irradiated silicon surfaces ablated by laser-induced breakdown spectroscopy

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Chinese Physics B 2018年第8期27卷 505-510页

作者： T Iqbal m Abrar m B Tahir m Seemab A majid S rafique Department of Physics Faculty of Sciences University of Gujrat Hafiz Hayat Campus Department of Physics Hazara University Mansehra Department of Physics University of Engineering and Technology (UET)Lahore Pakistan

Low energy metallic ions, generated by a Q-switched Nd：YAG laser （1064-nm wavelength, 10-mJ energy, 9-nm 12-ns-pulse width, 1011 W/cm2 intensity） irradiated on a silicon substrate to modify various properties, such as electrical, morphological, and structural modifications. Thomson parabola technique is used to calculate the energy of these metallic ions whereas the electrical conductivity is calculated with the help of Four-point probe. Interestingly circular tracks forming chain like damage trails are produced via these energetic ions which are carefully examined by optical microscopy. It is observed that excitation, ionization, and cascade collisions are responsible for surface modifications of irradiated samples. Four-point probe analysis revealed that the electrical conductivity of substrate has reduced with increasing trend of atomic number of irradiated metallic ions （A1, Ti, Cu, and Au）. The x-ray diffraction analysis elucidated the crystallographic changes leading to reduction of grain size of N-type silicon substrate, which is also associated with the metallic ions used. The decreasing trend of conductivity and grain size is due to thermal stresses, scattering effect, structural imperfections, and non-uniform conduction of energy absorbed by substrate atoms after the ion irradiation.

关键词： ablation Thomson parabola technique four-point probe

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Effect of Co substitution on the structural,electrical,and magnetic properties of Bi_(0.9)La_(0.1)FeO_3 by sol-gel synthesis

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International Journal of minerals,metallurgy and materials 2013年第2期20卷 166-171页

作者： Ghulam Ali Saadat A.Siddiqi shahid m.Ramay shahid Atiq murtaza Saleem Centre of Excellence in Solid State Physics University of the Punjab Interdisciplinary Research Centre in Biomedical materials COMSATS Institute of Information Technology Chemical Engineering Department College of EngineeringKing Saud University

Cobalt （Co）-doped ***3 multiferroics were synthesized by a sol-gel method based on the auto- combustion technique. As-synthesized powder was examined using various characterization techniques to explore the effect of Co substitution on the properties of Bi0.9La0.1FeO3. X-ray diffraction reveals that Co-doped Bi0.9La0.1FeO3 preserves the perovskite-type rhombohedral structure of BiFeO3, and the composition without Co preserves the original structure of the phase; however, a second-phase Bi2Fe409 has been identified in all other compositions. Surface morphological studies were performed by scanning electron microscopy. Temperature-dependent resistivity of the samples reveals the characteristic insulating behavior of the multiferroic material. The resistivity is found to decrease with the increase both in temperature and Co content. Room temperature frequency-dependent dielectric measurements were also reported. magnetic measurements show the enhancement in magnetization with the increase in Co content.

关键词： multiferroics cobalt doping microstructure electric properties magnetic properties sol-gel process

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