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Perveiz Khalid

Bio: Perveiz Khalid is an academic researcher from University of the Punjab. The author has contributed to research in topics: Geology & Petrophysics. The author has an hindex of 13, co-authored 63 publications receiving 492 citations. Previous affiliations of Perveiz Khalid include Yenepoya University & P A College of Engineering.


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TL;DR: In this paper, the two-phase isentropic compressibility (or inverse bulk modulus) is expressed in terms of isothermal compressibility, thermal expansivity and apparent heat capacity, defined as the partial derivative of total enthalpy with respect to temperature at constant pressure and composition.

43 citations

Journal Article
TL;DR: A large number of nanoparticles are present in the environment in which some are unintentionally produced; some are intentionally produced; and a mechanistic explanation of the reported toxicity remains incomprehensible.
Abstract: A large number of nanoparticles are present in the environment in which some are unintentionally produced; ultra fine particles or intentionally produced engineered nanoparticle (ENPs). The carbon based ENPs include singlewalled and multi walled carbon nanotubes (SWCNTs and MWCNTs), spherical fullerenes and dendrimers. Among all ENPs, the carbon based ENPs are attracting much attention for potential biomedical applications, such as biosensors design, drug design, drug delivery, tumor therapy and tissue engineering, because of their electronic, optical and mechanical properties. The pristine CNTs are inert in nature so it needs to be functionalized to make it reactive. The functionalization appends different functional group e.g. C=O, C–O, –OH and –COOH to CNTs, which make it dispersible and suitable for different applications. The biocompatibility of these functionalized CNTs and their composite has to be tested before real time applications in the biological system. Determining the toxicity of CNT is the most persistent questions in nanotechnology. Inconsistent reports on toxicity of CNTs often appear in the literature and a mechanistic explanation of the reported toxicity remains incomprehensible. Results from various scientific tests on cells have so far proven confusing, with some results indicating it to be highly toxic and others showing no signs of toxicity. Several toxicity mechanisms have been proposed for CNTs including interruption of trans membrane electron transfer, disruption/penetration of the cell envelope, oxidation of cell components, and production of secondary products such as dissolved heavy metal ions or reactive oxygen species (ROS).Toxicity of a CNT sample is dependent on its composition along with its geometry and surface functionalization. Several studies have suggested that wellfunctionalized CNTs are safe to animal cells, while raw CNTs or CNTs without functionalization show severe toxicity to animal or human cells at even moderate dosage.

39 citations

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TL;DR: In this article, an integrated approach is adopted to discriminate between lithologies and fluid saturation in the above-mentioned sand intervals, where seismic velocities are modeled using the Xu-White clay-sand mixing rock physics model.
Abstract: The sand intervals of the Lower Goru Formation of the Cretaceous age, widely distributed in the Middle and Lower Indus Basin of Pakistan, are proven reservoirs. However, in the Sawan gas field of the Middle Indus Basin, these sandstone intervals are very deep and extremely heterogeneous in character, which makes it difficult to discriminate lithologies and fluid saturation. Based on petrophysical analysis and rock physics modeling, an integrated approach is adopted to discriminate between lithologies and fluid saturation in the above-mentioned sand intervals. The seismic velocities are modeled using the Xu–White clay–sand mixing rock physics model. The calibrated rock physics model shows good consistency between measured and modeled velocities. The correlation between measured and modeled P and S wave velocities is 92.76% and 84.99%, respectively. This calibrated model has been successfully used to estimate other elastic parameters, even in those wells where both shear and sonic logs were missing. These estimated elastic parameters were cross-plotted to discriminate between the lithology and fluid content in the target zone. Cross plots clearly separate the shale, shaly sand, and gas-bearing sand clusters, which was not possible through conventional petrophysical analysis. These data clusters have been exported to the corresponding well for the purpose of interpolation between wells and to analyze the lateral and vertical variations in lithology and fluid content in the reservoir zone.

34 citations

Journal ArticleDOI
TL;DR: Cell viability decreased with an increase in CNT concentration indicating that MWCNTs and its composite can be cytotoxic at higher dosages, and provides further evidence that the bionano interface can be developed for CNT-reinforced HA composites for load-bearing bone implants, drug delivery, and tissue engineering.
Abstract: As a bone mineral component, hydroxyapatite (HA) has been an attractive bioceramic for the reconstruction of hard tissues. However, its poor mechanical properties, including low fracture toughness and tensile strength, have been a substantial challenge to the application of HA for the replacement of load-bearing and/or large bone defects. In this study, HA is reinforced with high-purity and well-functionalized multiwalled carbon nanotubes (MWCNTs; >99 wt%) having an average diameter of 15 nm and length from 10 to 20 μm. The cellular response of these functionalized CNTs and its composites were examined in human osteoblast sarcoma cell lines. Calcium nitrate tetrahydrate (Ca(NO3)2·4H2O) and diammonium hydrogen phosphate ((NH4)2HPO4) were used to synthesize HA in situ. MWCNTs were functionalized by heating at 100°C in 3:1 ratio of sulfuric acid and nitric acid for 60 min with stirring and dispersed in sodium dodecyl benzene sulfonate by sonication. HA particles were produced in MWCNTs solution by adding Ca(NO3)2·4H2O and (NH4)2HPO4 under vigorously stirring conditions. The composite was dried and washed in distilled water followed by heat treatment at 250°C to obtain CNT-HA powder. Physiochemical characterization of the composite material was carried out using Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, energy-dispersive X-ray spectrometer, and X-ray diffractometer. Furthermore, this study investigates the cytotoxic effects of functionalized-MWCNTs (f-MWCNTs) and its composites with HA in human osteoblast sarcoma cell lines. Human osteoblast cells were exposed with different concentrations of f-MWCNTs and its composite with HA. The interactions of f-MWCNT and MWCNT-HA composites were analyzed by 3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. The results indicate no detrimental effect on survival or mitochondrial activity of the osteoblast cells. Cell viability decreased with an increase in CNT concentration indicating that MWCNTs and its composite can be cytotoxic at higher dosages. This result provides further evidence that the bionano interface can be developed for CNT-reinforced HA composites for load-bearing bone implants, drug delivery, and tissue engineering.

34 citations

Journal ArticleDOI
TL;DR: In this article, the role of plants and their different parts for the synthesis of silver nanoparticles and their antibacterial applications is highlighted and the effect of different experimental parameters on the size of nanoparticles is also described.
Abstract: In the recent times, fabrication of metallic nanoparticles has become an enthralling area of research in the field of materials science. Among all, silver nanoparticles have taken the position of talented candidate for the modern study because of their efficient applications in biomedical field. Various chemical and physical routs have been explored for the synthesis of silver nanoparticles. However, green synthesis is found to be the most advantageous, environment-friendly, exciting and easily adoptable pathway over the other conventional approaches. In this review, we have highlighted the role of plants and their different parts for the synthesis of silver nanoparticles and their antibacterial applications. Moreover, the effect of different experimental parameters on the size of nanoparticles is also described.

32 citations


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6,278 citations

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TL;DR: Interpretation theory in applied geophysics: Grant, F S as mentioned in this paper, Unknown Binding, January 1, 1965 5.0 out of 5 stars 1 rating. Read it now.
Abstract: Interpretation theory in applied geophysics: Grant, F S ... Interpretation theory in applied geophysics Unknown Binding – January 1, 1965 5.0 out of 5 stars 1 rating. See all formats and editions Hide other formats and editions. The Amazon Book Review Book recommendations, author interviews, editors' picks, and more. Read it now. Enter your mobile number or email address below and we'll send you a ...

1,007 citations

01 Jan 2014

872 citations

01 Mar 2004
TL;DR: In this article, a theoretical model is presented for the behavior of rod-like particles representing CNTs in electrospinning, and the degrees of orientation of polymer, surfactant, and MWCNT are studied using X-ray dif...
Abstract: The electrospinning process was used successfully to fabricate nanofibers of poly(ethylene oxide) (PEO) in which multiwalled carbon nanotubes (MWCNT) are embedded. Initial dispersion of MWCNTs in water was achieved using amphiphiles, either as small molecules (sodium dodecyl sulfate, SDS) or as a high molecular weight, highly branched polymer (Gum Arabic). These dispersions provided separation of the MWCNTs and their individual incorporation into the PEO nanofibers by subsequent electrospinning. The focus of this work is on the development of axial orientations in these multicomponent nanofibers. A theoretical model is presented for the behavior of rodlike particles representing CNTs in electrospinning. Initially the rods are randomly oriented, but due to the sinklike flow in a wedge they are gradually oriented mainly along the stream lines, so that straight CNTs are almost oriented upon entering the electrospun jet. The degrees of orientation of polymer, surfactant, and MWCNT were studied using X-ray dif...

445 citations

Journal ArticleDOI
TL;DR: In this literature review the biologically inspired scaffolds, bone substitutes, implants characterized by mechanical strength and biocompatibility, as well the drug delivery systems, based on hydroxyapatite are discussed.

429 citations