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Shah S.A.,Forman Christian College | Hashmi M.U.,The University of Lahore | Alam S.,Pakistan Council of Scientific and Industrial Research
Materials Science and Engineering C | Year: 2011

The magnetic and heat generating properties of the ferrimagnetic zinc-ferrite containing bioactive glass ceramics have been enhanced by aligning magnetic field, without any compositional or micro-structural changes in the material. The glass ceramics were heated to 600 °C and cooled in an aligning magnetic field of 1 T. Magnetically aligned samples were compared with the non-aligned samples. VSM measurements taken at 500 Oe showed that coercive force, remanance magnetization and hysteresis area increased for the aligned samples. This occurred because the aligning magnetic field setup an easy axis for the magnetic domains. After cooling, the domains were trapped and became stable along the direction of aligning field. Now stronger magnetic field was required to turn the domains away from their aligned positions. Thus magnetic properties were enhanced by the aligning magnetic field and it led to enhance the heat generation under magnetic induction furnace operating at 500 Oe and 60 kHz for 2 min. Data showed that maximum specific power loss and temperature increase after 2 min were 4.4 W/g and 6.3 °C respectively for the aligned sample of maximum zinc-ferrite crystalline content having pseudo single domain crystalline structure. The glass ceramics were immersed in simulated body fluid over weeks. FTIR, SEM and EDX results indicated the growth of precipitated Hydroxyapatite suggesting the bioactivity of the materials. © 2011 Elsevier B.V. All rights reserved. Source


Nasir S.,Pakistan Council of Scientific and Industrial Research | Sarfaraz T.B.,University of Karachi | Verheyen T.V.,Australian Sustainable Industry Research Center Ltd. | Chaffee A.L.,Monash University
Fuel Processing Technology | Year: 2011

The present paper describes the characterization of Pakistan lignite coal, derived humic acids (HAL) and nitrohumic acids (NHA) along with the standard leonardite humic acids (LHA). The study utilized chromatographic and spectroscopic techniques to characterize the structure of coal and derived materials. Pyrolysis coupled to gc/ms was conducted with and without methylating agent (tetramethyl ammonium hydroxide). The pyrolysis study resulted in releasing mainly fatty acid methyl esters, different series of hydrocarbons and α, ω-dicarboxylic acid methyl esters. Triterpenoids, syringic and ρ-coumaric compounds and aromatic compounds derived from lignin moieties were also detected. Fourier transform infrared (FT-IR) and NMR data helped to evaluate the influence of coal rank on regeneration and nitration processes with respect to chemical structural composition of coal and derived materials. FT-IR spectra of four materials were similar except that NHA showed an absorption band at 1532 cm-1, thus confirming the presence of -NO2 groups. 13C NMR indicated higher aromaticity and less hydroxylalkyl material in HAL than NHA. The elemental composition and acid functional group content of four materials were also reported. The combination of results from different analytical techniques gives an improved understanding of the Pakistan coal nature and helpful for its future utilization. © 2010 Elsevier B.V. Source


Shah S.A.,The University of Lahore | Hashmi M.U.,The University of Lahore | Shamim A.,The University of Lahore | Alam S.,Pakistan Council of Scientific and Industrial Research
Applied Physics A: Materials Science and Processing | Year: 2010

For the hyperthermia therapy of cancer, ferrimagnetic glass ceramics are a potential candidate. Ferrimagnetic zinc-ferrite-containing bioactive glass ceramics were prepared by quenching the glass ceramics from sintering temperature. Then the samples were heated to 600°C and cooled in an aligning magnetic field of 1 Tesla to cause anisotropy. The magnetically aligned samples were compared with non-aligned samples. Vibrating sample magnetometry measurements at 10 kOe showed that the magnetic properties were enhanced by the aligning magnetic field and it led to an enhancement of the magnetic heat generation under a magnetic induction furnace operating at 500 Oe and 400 kHz for 2 min. Data showed that the maximum specific power loss and temperature increase after 2 min were 31.5 W/g and 45°C, respectively, for the aligned sample of maximum zinc-ferrite crystalline content. The glass ceramics were immersed in simulated body fluid for 3 weeks. X-ray diffraction and Fourier transform infrared and atomic absorption spectroscopy results indicated the growth of precipitated hydroxyapatite, suggesting that the ferrimagnetic glass ceramics were bioactive and could bond to living tissues in physiological environment. © 2010 Springer-Verlag. Source


Veesar I.A.,University of Sindh | Memon S.,University of Sindh | Syed M.N.,Pakistan Council of Scientific and Industrial Research
Biochemical Engineering Journal | Year: 2013

The present article describes formation of excipient-CRL complex from water soluble calix[4]arene derivative (3 as excipient) and Candida rugosa lipase (CRL), which is proposed as a reusable form of enzyme that is free from steric and diffusion limitations associated with those enzymes immobilized onto porous solid supports. The excipient-CRL could completely hydrolyze 50. mM p-nitrophenyl palmitate (p-NPP) in Tris-HCl buffer at a wide range of temperatures, i.e. 30-80. °C. It is stable under stirred conditions and could be reused multiple times without loss of enzyme activity. It was observed that excipient-CRL complex shows a significant effect on the enzyme activity with an enhancement in thermal stability, while pH and temperature affect the activity of excipient-CRL as well as free CRL. Consequently, the excipient-CRL was found more active than free CRL for the hydrolysis of p-NPP in respect of its reusability. © 2013 Elsevier B.V. Source


Shah S.A.,Forman Christian College | Majeed A.,Nazareth Hospital | Rashid K.,Pakistan Council of Scientific and Industrial Research | Awan S.-U.,Quaid-i-Azam University
Materials Chemistry and Physics | Year: 2013

Superparamagnetic iron oxide-based nanoparticles (SPIONS) have attracted an enormous attention for their potential use in biomedical applications due to their good biocompatibility and low toxicity. Current study is about doxorubicin-loaded multifunctional MnFe2O4 nanoparticles surface-modified with polyethylene glycol (PEG) & folic acid (FA) for multimodal cancer therapy. Infrared spectroscopy and thermogravimetric data confirmed this surface modification. Nanoparticles were of moderate colloidal dispersion due to PEG coating. Composite nanoparticles having mean diameter of about 22 nm were of core-shell structure having about 31% (wt) organic shell over the (remaining) magnetic core. MnFe2O4 core of about 16 nm was superparamagnetic due to the pseudo-single domain structure. Drug loading & releasing were efficient in the initial 8 h and gradual in later hours. Magnetic heating was studied by exposing the magnetic fluid to high frequency magnetic field. Temperature of the fluid rose to 45 °C from 25 °C in about 22 min, which is an effective and appropriate temperature for the localized hyperthermia treatment of cancer. © 2013 Elsevier B.V. All rights reserved. Source

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