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Papers by Saqlain Shah

The aim of present work is to study the relationship between crystalline phases, microstructure a... more The aim of present work is to study the relationship between crystalline phases, microstructure and mechanical properties of bioactive glass-ceramics. For this purpose, glasses of composition (50-x) CaO–34SiO2–14.5P2O5–1 CaF2–0.5MgF2– x MgO (wt. %) (where x = 4, 25 and 46 respectively) were synthesized by conventional melt-quench method. Each glass was sintered according to the endothermal and exothermal peaks of differential scanning calorimetric (DSC) data to form three glass ceramics termed G1, G2 and G3 respectively. X-ray diffraction (XRD) revealed crystalline phases of hydroxyapatite and wollastonite in G1 and G2, whereas in G3, a new phase ‘whitlockite’ was observed probably due to a greater concentration of MgO in this sample. Bulk density of the samples was determined by Archimedes principle. Scanning electron microscope (SEM) data illustrated that the rate of densification of materials increased with the decrease of CaO/MgO ratio. Analysis of mechanical properties revealed...

Plasmonics III

Surface enhanced Raman spectroscopy (SERS) is capable of sensing not only the chemical nature but... more Surface enhanced Raman spectroscopy (SERS) is capable of sensing not only the chemical nature but also the biological organisms. In this work, it is experimentally demonstrated that silver and reduced graphene oxide nano-composite based material can be used as SERS platform. Localized surface plasmon resonance (LSPR) property of silver nanostructure such as nano-sphere, nano-dendrites and nano-prism and high impermeability of reduced graphene oxide (RGO) have been employed to build a composite for SERS measurements. Graphene oxide was synthesized using Hummer’s Method and then simple facile method was used for its reduction as well as for the deposition of silver nanostructure on it. SEM, XRD, FTIR, and UV-Vis techniques characterized the prepared nano-composite of Ag-RGO. The composite material was used for SERS measurement for the detection of Escherichia Coli (E. Coli) bacteria at a concentration of 8×106 CFU/ ml and it is observed that signal of silver nanodentries-RGO composite was intense in comparison with Ag-RGO nano-sphere and nano-triangular composite.

Sarhad Journal of Agriculture, 1990

Abstract For 45 days, 8 growing buffaloes were fed on diets containing wheat straw untreated or t... more Abstract For 45 days, 8 growing buffaloes were fed on diets containing wheat straw untreated or treated with 10% calcium hydroxide solution and concentrate containing 49% wheat bran, 50% cottonseed cake and 0.5% salt. Limestone was added to the diet of the ...

Journal of Tissue Engineering and Regenerative Medicine

The importance of bone scaffolds has increased many folds in the last few years; however, during ... more The importance of bone scaffolds has increased many folds in the last few years; however, during bone implantation, bacterial infections compromise the implantation and tissue regeneration. This work is focused on this issue while not compromising on the properties of a scaffold for bone regeneration. Biocomposite scaffolds (BS) were fabricated via the freeze–drying technique. The samples were characterized for structural changes, surface morphology, porosity, and mechanical properties through spectroscopic (Fourier transform‐infrared [FT‐IR]), microscopic (scanning electron microscope [SEM]), X‐ray (powder X‐ray diffraction and energy‐dispersive X‐ray), and other analytical (Brunauer–Emmett–Teller, universal testing machine Instron) techniques. Antibacterial, cellular, and hemocompatibility assays were performed using standard protocols. FT‐IR confirmed the interactions of all the components. SEM illustrated porous and interconnected porous morphology. The percentage porosity was in the range of 49.75%–67.28%, and the pore size was 215.65–470.87 µm. The pore size was perfect for cellular penetration. Thus, cells showed significant proliferation onto these scaffolds. X‐ray studies confirmed the presence of nanohydroxyapatite and graphene oxide (GO). The cell viability was 85%–98% (BS1–BS3), which shows no significant toxicity of the biocomposite. Furthermore, the biocomposites exhibited better antibacterial activity, no effect on the blood clotting (normal in vitro blood clotting), and less than 5% hemolysis. The ultimate compression strength for the biocomposites increased from 4.05 to 7.94 with an increase in the GO content. These exciting results revealed that this material has the potential for possible application in bone tissue engineering.

Materials Chemistry and Physics

Abstract We have studied structural, optical, electronic and magnetic properties of undoped well ... more Abstract We have studied structural, optical, electronic and magnetic properties of undoped well crystalline hexagonal and non-hexagonal ZnO system. X-ray diffraction (XRD) and high resolution transmission electron micrographs (HRTEM) of air annealed at 550 °C (sample-d) confirmed the presence of hexagonal (wurtzite) single phase ZnO. Raman analysis detected the vibrations of fundamental and second order phonons of Zn and oxygen related species. In Photoluminescence (PL) spectra, we observed that the intensity of UV peak decreases as annealing temperature increases. Broad PL visible band of samples shifted towards lower wavelength due to annealing effects. Fitting of broad PL spectra confirmed the existence of Zinc interstitial (Zni), Zinc vacancy (VZn) and oxygen vacancy (Vo) defects. To determine the Zn interstitial and vacancy defects Auger peaks were de-convoluted from X-ray photoelectron spectroscopy (XPS) survey scan. Oxygen vacancies are estimated by fitting of asymmetric XPS O-1s spectra. Incomplete oxidation of magnetization versus temperature in the presence of applied field showed the presence of irreversibility in 550 °C annealed-sample. Zn clusters and secondary phases are may be reason of room temperature ferromagnetism in non-hexagonal samples (a-c). While, complex defect (zinc and oxygen vacancies) as observed in electronic and PL data may be responsible for inducing, promoting and stabilizing room temperature ferromagnetism in well crystalline hexagonal ZnO nanoparticles (sample-d).

Journal of Magnetism and Magnetic Materials, 2017

Abstract The NiZn nanowires arrays were prepared into anodized aluminum oxide (AAO) templates by ... more Abstract The NiZn nanowires arrays were prepared into anodized aluminum oxide (AAO) templates by alternating current (AC) using electrochemical deposition (ECD). We have tuned the magnetic and structural properties of NiZn nanowires by changing the AC potential from 12 to 17 V. The samples were characterized by different elemental, compositional, structural and magnetic properties analysis. The X-ray diffraction shows that the nanowires are polycrystalline with dominant FCC phase and grain size calculated by Debye Scherrer formula is found to be 27 nm. Atomic force microscopy (AFM) was used for surface analysis which showed surface roughness ∼5 µm. The SQUID (superconducting quantum interference device) is used for magnetic properties analysis and it showed ferromagnetic nature of the samples which were expected because of the presence of Ni. The potential dependent coercivity and saturation magnetization was calculated which were variable and their maximum values are 68 Oe and 49.22 µemu respectively explained on the basis defects induced blocking of magnetic domain wall motion.

Smart Materials and Structures, 2015

This work was financially supported by Higher Education Commission (HEC) of Pakistan under '5... more This work was financially supported by Higher Education Commission (HEC) of Pakistan under '5000 Indigenous PhD fellowship program' for granting the doctoral scholarship ((Pin-No 041-211772 P-108) to Saif Ullah Awan. It was further supported by HEC project 'Development and Study of Magnetic Nanostructures' allotted to head of magnetism Lab, Professor Dr S K Hasanain, Department of Physics, Quaid-i-Azam University, Islamabad, Pakistan.

2015 5th International Workshop on Magnetic Particle Imaging (IWMPI), 2015

Magnetic particle imaging (MPI) relies on the specific non-linear magnetization response of super... more Magnetic particle imaging (MPI) relies on the specific non-linear magnetization response of superparamagnetic nanoparticle tracers for signal generation. Tracers should be tuned for optimal size distributions and magnetization responses under alternating magnetic field. Therefore, comprehensive understanding of the nanoparticle magnetization dynamics is necessary for producing efficient MPI tracers. In this study, we evaluated the dynamics of magnetization reversal of an optimized MPI tracer [1] after restricting the particle's motion by freezing the solvent. Furthermore, we used an aligning field during freezing to introduce a preferred magnetization direction. The results indicate that the tracer magnetization response can be approximated by an effective uniaxial anisotropy despite the particle's cubic point group symmetry.

Progress in Natural Science: Materials International, 2014

In this work, powders of three different compositions, each having 34 SiO 2-14.5 P 2 O 5-1 CaF 2-... more In this work, powders of three different compositions, each having 34 SiO 2-14.5 P 2 O 5-1 CaF 2-0.5 MgF (% wt) and ratio of CaO/MgO varying from 11.5:1 to 1:11.5 were thoroughly mixed and melted under oxy-acetylene flame in a fire clay crucible that made the glass formation cheaper in time and cost. The melt of each composition was quenched in water to form three different glasses. Every glass was sintered at 950°C to form three glass ceramics named G1, G2 and G3 respectively. To study the dissolution behavior, each sample was immersed in a simulated body fluid (SBF) for 2, 5, 10, 20 and 25 days at room temperature. Thin film XRD analysis revealed that the samples with larger CaO/MgO ratio exhibited better bioactivity. pH of SBF increased efficiently in case of G1 whereas in case of G2 and G3, this increase was slower due to greater amount of MgO. The concentrations of Ca, P, Mg and Si ions were measured by Atomic Absorption Spectroscopy. EDS analysis showed the increase in P and Ca ions and presence of C in G1 after 5 days immersion and after 10 days, in case of G2 indicating the higher formation rate of hydroxycarbonate Apatite layer in G1 as compared to G2 due to greater CaO/MgO ratio whereas in G3 Mg-hydroxycarbonate apatite (Ca(Mg) 5 (CO 3)(PO 4) 3 (OH)) (heneuite) layer was recognized after 20 days showing the least bioactivity due to very large amount of Mg and the least CaO/MgO ratio.

Materials Science and Engineering: C, 2011

... Effect of aligning magnetic field on the magnetic and calorimetric properties of ferrimagneti... more ... Effect of aligning magnetic field on the magnetic and calorimetric properties of ferrimagnetic bioactive glass ceramics for the hyperthermia treatment of cancer. Saqlain A. Shah a , low asterisk , E-mail The Corresponding Author , MU Hashmi b and S. Alam c. ...

Journal of Applied Physics, 2014

Memory and switching devices acquired new materials which exhibit ferroelectric and ferromagnetic... more Memory and switching devices acquired new materials which exhibit ferroelectric and ferromagnetic order simultaneously. We reported multiferroic behavior in Zn 1Ày Li y O(0.00 y 0.10) nanoparticles. The analysis of transmission electron micrographs confirmed the hexagonal morphology and wurtzite crystalline structure. We investigated p-type conductivity in doped samples and measured hole carriers in range 2.4 Â 10 17 /cc to 7.3 Â 10 17 /cc for different Li contents. We found that hole carriers are responsible for long range order ferromagnetic coupling in Li doped samples. Room temperature ferroelectric hysteresis loops were observed in 8% and 10% Li doped samples. We demonstrated ferroelectric coercivity (remnant polarization) 2.5 kV/cm (0.11 lC/cm 2) and 2.8 kV/cm (0.15 lC/cm 2) for y ¼ 0.08 and y ¼ 0.10 samples. We propose that the mechanism of Li induced ferroelectricity in ZnO is due to indirect dipole interaction via hole carriers. We investigated that if the sample has hole carriers !5.3 Â 10 17 /cc, they can mediate the ferroelectricity. Ferroelectric and ferromagnetic measurements showed that higher electric polarization and larger magnetic moment is attained when the hole concentration is larger and vice versa. Our results confirmed the hole dependent coexistence of ferromagnetic and ferroelectric behavior at room temperature, which provide potential applications for switchable and memory devices. V

Applied Nanoscience, 2013

This is a vital extension of our previously published work. Thermo-responsive copolymer coated su... more This is a vital extension of our previously published work. Thermo-responsive copolymer coated superparamagnetic MnFe 2 O 4 nanoparticles are tested for cell viability and affinity on HeLa carcinoma cells under different conditions. Nanoparticles were loaded with anticancer drug doxorubicin. Composite nanoparticles of average diameter 45 nm were of core-shell structure having magnetic core of about 18 nm. Magnetic hyperthermia effects on cell viability and drug delivery were studied by exposing the cell suspension to high frequency magnetic field, and living cells were quantified using MTT method. There was almost absence of drug release at 37°C. Drug was released at temperatures above lower critical solution temperature (LCST) by magnetic heating. LCST of the thermo-responsive copolymer was observed to be around 39°C. Below this temperature, copolymer was hydrophilic and swelled. But above LCST, copolymer could become hydrophobic, expel water and drug and shrink in volume. Combination of hyperthermia and drug delivery effectively treated cancer cells.

International Nano Letters, 2012

Controlled conduction of magnetic spins is desired for data processing in modern spintronic devic... more Controlled conduction of magnetic spins is desired for data processing in modern spintronic devices. Transition metal-doped ZnO is a potential candidate for this purpose. We studied the effects of cobalt doping on structural, absorbance, and magnetic properties of ZnO nano-particles. Different compositions (Zn0.99Co0.1O, Zn0.97Co0.3O, and Zn0.95Co0.5O) of cobalt-doped ZnO were fabricated using metallic chlorides by co-precipitation method. XRD revealed standard ZnO wurtzite crystal structure without lattice distortion due to impurities but showed presence of additional phases at higher doping ratios. Fourier transformed infrared spectroscopy also confirmed the standard ZnO profiles at lower doping ratios but additional phases at higher doping. Vibrating sample magnetometer showed soft ferromagnetic behavior for low impurity samples and harder ferromagnetic behavior for higher doping at room temperature. A simultaneous differential scanning calorimetry/thermo gravimetric analysis was...

Journal of Magnetism and Magnetic Materials, 2010

Glass ceramics of the composition xZnO Á 25Fe 2 O 3 Á (40 À x)SiO 2 Á 25CaO Á 7P 2 O 5 Á 3Na 2 O ... more Glass ceramics of the composition xZnO Á 25Fe 2 O 3 Á (40 À x)SiO 2 Á 25CaO Á 7P 2 O 5 Á 3Na 2 O were prepared by the melt-quench method using oxy-acetylene flame. Glass-powder compacts were sintered at 1100 1C for 3 h and then rapidly cooled at À 10 1C. X-ray diffraction (XRD) revealed 3 prominent crystalline phases: ZnFe 2 O 4 , CaSiO 3 and Ca 10 (PO 4) 6 (OH) 2. Vibrating sample magnetometer (VSM) data at 10 KOe and 500 Oe showed that saturation magnetization, coercivity and hence hysteresis area increased with the increase in ZnO content. Nano-sized ZnFe 2 O 4 crystallites were of pseudo-single domain structure and thus coercivity increased with the increase in crystallite size. ZnFe 2 O 4 exhibited ferrimagnetism due to the random distribution of Zn 2 + and Fe 3 + cations at tetrahedral A sites and octahedral B sites. This inversion/random distribution of cations was probably due to the surface effects of nano-ZnFe 2 O 4 and rapid cooling of the material from 1100 1C (thus preserving the high temperature state of the random distribution of cations). Calorimetric measurements were carried out using magnetic induction furnace at 500 Oe magnetic field and 400 KHz frequency. The data showed that maximum specific power loss and temperature increase after 2 min were 26 W/g and 37 1C, respectively for the sample containing 10% ZnO. The samples were immersed in simulated body fluid (SBF) for 3 weeks. Scanning electron microscope (SEM), energy dispersive spectroscopy (EDX) and XRD results confirmed the growth of precipitated hydroxyapatite phase after immersion in SBF, suggesting that the ferrimagnetic glass ceramics were bioactive and could bond to the living tissues in physiological environment.

This paper presents a novel hypothesis on the function of massive feedback pathways in mammalian ... more This paper presents a novel hypothesis on the function of massive feedback pathways in mammalian visual systems. We propose that the cortical feature detectors compete not for the right to represent the output at a point, but for exclusive rights to abstract and represent part of the underlying input. Feedback can do this very naturally. A computational model that implements the above idea for the problem of line detection is presented and based on that we suggest a functional role for the thalamo-cortical loop during perception of lines. We show that the model successfully tackles the so called Cross problem. Based on some recent experimental results, we discuss the biological plausibility of our model. We also comment on the relevance of our hypothesis (on the role of feedback) to general sensory information processing and recognition.

Fusion engineering and …, 2001

This paper presents the control system overview, hardware, software and network for Data acquisit... more This paper presents the control system overview, hardware, software and network for Data acquisition and Control system for steady state neutral beam injector (NBIDACS) to be used for heating of plasma in steady state superconducting tokamak (SST-1). The task for NBIDACS is not ...

BJOG: An International Journal …, 2001

Results Women from social classes II and I and women who live in the south of England were more l... more Results Women from social classes II and I and women who live in the south of England were more likely to use hormone replacement therapy independently of a range of socio-demographic factors including education. The adjusted odds ratio for social classes II and I compared ...

Ophthalmology, 2000

Mean IOP was 19.80 mmHg at 8:00 (95% confidence interval [CI], 18.95–20.66 mmHg), 20.38 mmHg at 1... more Mean IOP was 19.80 mmHg at 8:00 (95% confidence interval [CI], 18.95–20.66 mmHg), 20.38 mmHg at 12:00 (95% CI, 19.49–21.26 mmHg), 19.91 mmHg at 4:00 (95% CI, 19.99–21.83 mmHg), and 19.23 mmHg at 8:00 (95% CI, 18.35–20.11 mmHg). Mean CCT was 569.4 ...

We have recently proposed that one way that plant growth-promoting rhizobacteria (PGPR) stimulate... more We have recently proposed that one way that plant growth-promoting rhizobacteria (PGPR) stimulate plant growth is through the activity of the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase, which causes a lowering of plant ethylene levels resulting in longer roots. As part of an effort to understand the role of this enzyme in PGPR, the genes for ACC deaminase from two PGPR, Enterobacter cloacae CAL2 and UW4, have been isolated. These genes are highly homologous to the ACC deaminase genes from Pseudomonas strains 6G5 and F17 and similar to the ACC deaminase gene from Pseudomonas sp. strain ACP. The region downstream (i.e., at the 3'-terminal end) of the strain UW4 ACC deaminase gene has a potential hairpin-like transcription termination site. The regions upstream of the strains UW4 and CAL2 ACC deaminase genes contain putative ribosome-binding sites; however, the promoter sequences have not yet been identified. Southern hybridization experiments suggest that there is a single copy of the ACC deaminase gene in Enterobacter cloacae strains UW4 and CAL2 and that there may be several different types of ACC deaminase genes in different microbes. The cloned ACC deaminase gene can be expressed in Escherichia coli enabling this bacterium to grow on ACC as a sole source of nitrogen and confers upon both Escherichia coli and Pseudomonas spp. strains that are transformed with this gene the ability to promote the elongation of the roots of canola seedlings.Key words: plant growth-promoting rhizobacteria, PGPR, 1-aminocyclopropane-1-carboxylate, ACC, ACC deaminase, ethylene, soil bacteria.

The aim of present work is to study the relationship between crystalline phases, microstructure a... more The aim of present work is to study the relationship between crystalline phases, microstructure and mechanical properties of bioactive glass-ceramics. For this purpose, glasses of composition (50-x) CaO–34SiO2–14.5P2O5–1 CaF2–0.5MgF2– x MgO (wt. %) (where x = 4, 25 and 46 respectively) were synthesized by conventional melt-quench method. Each glass was sintered according to the endothermal and exothermal peaks of differential scanning calorimetric (DSC) data to form three glass ceramics termed G1, G2 and G3 respectively. X-ray diffraction (XRD) revealed crystalline phases of hydroxyapatite and wollastonite in G1 and G2, whereas in G3, a new phase ‘whitlockite’ was observed probably due to a greater concentration of MgO in this sample. Bulk density of the samples was determined by Archimedes principle. Scanning electron microscope (SEM) data illustrated that the rate of densification of materials increased with the decrease of CaO/MgO ratio. Analysis of mechanical properties revealed...

Plasmonics III

Surface enhanced Raman spectroscopy (SERS) is capable of sensing not only the chemical nature but... more Surface enhanced Raman spectroscopy (SERS) is capable of sensing not only the chemical nature but also the biological organisms. In this work, it is experimentally demonstrated that silver and reduced graphene oxide nano-composite based material can be used as SERS platform. Localized surface plasmon resonance (LSPR) property of silver nanostructure such as nano-sphere, nano-dendrites and nano-prism and high impermeability of reduced graphene oxide (RGO) have been employed to build a composite for SERS measurements. Graphene oxide was synthesized using Hummer’s Method and then simple facile method was used for its reduction as well as for the deposition of silver nanostructure on it. SEM, XRD, FTIR, and UV-Vis techniques characterized the prepared nano-composite of Ag-RGO. The composite material was used for SERS measurement for the detection of Escherichia Coli (E. Coli) bacteria at a concentration of 8×106 CFU/ ml and it is observed that signal of silver nanodentries-RGO composite was intense in comparison with Ag-RGO nano-sphere and nano-triangular composite.

Sarhad Journal of Agriculture, 1990

Abstract For 45 days, 8 growing buffaloes were fed on diets containing wheat straw untreated or t... more Abstract For 45 days, 8 growing buffaloes were fed on diets containing wheat straw untreated or treated with 10% calcium hydroxide solution and concentrate containing 49% wheat bran, 50% cottonseed cake and 0.5% salt. Limestone was added to the diet of the ...

Journal of Tissue Engineering and Regenerative Medicine

The importance of bone scaffolds has increased many folds in the last few years; however, during ... more The importance of bone scaffolds has increased many folds in the last few years; however, during bone implantation, bacterial infections compromise the implantation and tissue regeneration. This work is focused on this issue while not compromising on the properties of a scaffold for bone regeneration. Biocomposite scaffolds (BS) were fabricated via the freeze–drying technique. The samples were characterized for structural changes, surface morphology, porosity, and mechanical properties through spectroscopic (Fourier transform‐infrared [FT‐IR]), microscopic (scanning electron microscope [SEM]), X‐ray (powder X‐ray diffraction and energy‐dispersive X‐ray), and other analytical (Brunauer–Emmett–Teller, universal testing machine Instron) techniques. Antibacterial, cellular, and hemocompatibility assays were performed using standard protocols. FT‐IR confirmed the interactions of all the components. SEM illustrated porous and interconnected porous morphology. The percentage porosity was in the range of 49.75%–67.28%, and the pore size was 215.65–470.87 µm. The pore size was perfect for cellular penetration. Thus, cells showed significant proliferation onto these scaffolds. X‐ray studies confirmed the presence of nanohydroxyapatite and graphene oxide (GO). The cell viability was 85%–98% (BS1–BS3), which shows no significant toxicity of the biocomposite. Furthermore, the biocomposites exhibited better antibacterial activity, no effect on the blood clotting (normal in vitro blood clotting), and less than 5% hemolysis. The ultimate compression strength for the biocomposites increased from 4.05 to 7.94 with an increase in the GO content. These exciting results revealed that this material has the potential for possible application in bone tissue engineering.

Materials Chemistry and Physics

Abstract We have studied structural, optical, electronic and magnetic properties of undoped well ... more Abstract We have studied structural, optical, electronic and magnetic properties of undoped well crystalline hexagonal and non-hexagonal ZnO system. X-ray diffraction (XRD) and high resolution transmission electron micrographs (HRTEM) of air annealed at 550 °C (sample-d) confirmed the presence of hexagonal (wurtzite) single phase ZnO. Raman analysis detected the vibrations of fundamental and second order phonons of Zn and oxygen related species. In Photoluminescence (PL) spectra, we observed that the intensity of UV peak decreases as annealing temperature increases. Broad PL visible band of samples shifted towards lower wavelength due to annealing effects. Fitting of broad PL spectra confirmed the existence of Zinc interstitial (Zni), Zinc vacancy (VZn) and oxygen vacancy (Vo) defects. To determine the Zn interstitial and vacancy defects Auger peaks were de-convoluted from X-ray photoelectron spectroscopy (XPS) survey scan. Oxygen vacancies are estimated by fitting of asymmetric XPS O-1s spectra. Incomplete oxidation of magnetization versus temperature in the presence of applied field showed the presence of irreversibility in 550 °C annealed-sample. Zn clusters and secondary phases are may be reason of room temperature ferromagnetism in non-hexagonal samples (a-c). While, complex defect (zinc and oxygen vacancies) as observed in electronic and PL data may be responsible for inducing, promoting and stabilizing room temperature ferromagnetism in well crystalline hexagonal ZnO nanoparticles (sample-d).

Journal of Magnetism and Magnetic Materials, 2017

Abstract The NiZn nanowires arrays were prepared into anodized aluminum oxide (AAO) templates by ... more Abstract The NiZn nanowires arrays were prepared into anodized aluminum oxide (AAO) templates by alternating current (AC) using electrochemical deposition (ECD). We have tuned the magnetic and structural properties of NiZn nanowires by changing the AC potential from 12 to 17 V. The samples were characterized by different elemental, compositional, structural and magnetic properties analysis. The X-ray diffraction shows that the nanowires are polycrystalline with dominant FCC phase and grain size calculated by Debye Scherrer formula is found to be 27 nm. Atomic force microscopy (AFM) was used for surface analysis which showed surface roughness ∼5 µm. The SQUID (superconducting quantum interference device) is used for magnetic properties analysis and it showed ferromagnetic nature of the samples which were expected because of the presence of Ni. The potential dependent coercivity and saturation magnetization was calculated which were variable and their maximum values are 68 Oe and 49.22 µemu respectively explained on the basis defects induced blocking of magnetic domain wall motion.

Smart Materials and Structures, 2015

This work was financially supported by Higher Education Commission (HEC) of Pakistan under '5... more This work was financially supported by Higher Education Commission (HEC) of Pakistan under '5000 Indigenous PhD fellowship program' for granting the doctoral scholarship ((Pin-No 041-211772 P-108) to Saif Ullah Awan. It was further supported by HEC project 'Development and Study of Magnetic Nanostructures' allotted to head of magnetism Lab, Professor Dr S K Hasanain, Department of Physics, Quaid-i-Azam University, Islamabad, Pakistan.

2015 5th International Workshop on Magnetic Particle Imaging (IWMPI), 2015

Magnetic particle imaging (MPI) relies on the specific non-linear magnetization response of super... more Magnetic particle imaging (MPI) relies on the specific non-linear magnetization response of superparamagnetic nanoparticle tracers for signal generation. Tracers should be tuned for optimal size distributions and magnetization responses under alternating magnetic field. Therefore, comprehensive understanding of the nanoparticle magnetization dynamics is necessary for producing efficient MPI tracers. In this study, we evaluated the dynamics of magnetization reversal of an optimized MPI tracer [1] after restricting the particle's motion by freezing the solvent. Furthermore, we used an aligning field during freezing to introduce a preferred magnetization direction. The results indicate that the tracer magnetization response can be approximated by an effective uniaxial anisotropy despite the particle's cubic point group symmetry.

Progress in Natural Science: Materials International, 2014

In this work, powders of three different compositions, each having 34 SiO 2-14.5 P 2 O 5-1 CaF 2-... more In this work, powders of three different compositions, each having 34 SiO 2-14.5 P 2 O 5-1 CaF 2-0.5 MgF (% wt) and ratio of CaO/MgO varying from 11.5:1 to 1:11.5 were thoroughly mixed and melted under oxy-acetylene flame in a fire clay crucible that made the glass formation cheaper in time and cost. The melt of each composition was quenched in water to form three different glasses. Every glass was sintered at 950°C to form three glass ceramics named G1, G2 and G3 respectively. To study the dissolution behavior, each sample was immersed in a simulated body fluid (SBF) for 2, 5, 10, 20 and 25 days at room temperature. Thin film XRD analysis revealed that the samples with larger CaO/MgO ratio exhibited better bioactivity. pH of SBF increased efficiently in case of G1 whereas in case of G2 and G3, this increase was slower due to greater amount of MgO. The concentrations of Ca, P, Mg and Si ions were measured by Atomic Absorption Spectroscopy. EDS analysis showed the increase in P and Ca ions and presence of C in G1 after 5 days immersion and after 10 days, in case of G2 indicating the higher formation rate of hydroxycarbonate Apatite layer in G1 as compared to G2 due to greater CaO/MgO ratio whereas in G3 Mg-hydroxycarbonate apatite (Ca(Mg) 5 (CO 3)(PO 4) 3 (OH)) (heneuite) layer was recognized after 20 days showing the least bioactivity due to very large amount of Mg and the least CaO/MgO ratio.

Materials Science and Engineering: C, 2011

... Effect of aligning magnetic field on the magnetic and calorimetric properties of ferrimagneti... more ... Effect of aligning magnetic field on the magnetic and calorimetric properties of ferrimagnetic bioactive glass ceramics for the hyperthermia treatment of cancer. Saqlain A. Shah a , low asterisk , E-mail The Corresponding Author , MU Hashmi b and S. Alam c. ...

Journal of Applied Physics, 2014

Memory and switching devices acquired new materials which exhibit ferroelectric and ferromagnetic... more Memory and switching devices acquired new materials which exhibit ferroelectric and ferromagnetic order simultaneously. We reported multiferroic behavior in Zn 1Ày Li y O(0.00 y 0.10) nanoparticles. The analysis of transmission electron micrographs confirmed the hexagonal morphology and wurtzite crystalline structure. We investigated p-type conductivity in doped samples and measured hole carriers in range 2.4 Â 10 17 /cc to 7.3 Â 10 17 /cc for different Li contents. We found that hole carriers are responsible for long range order ferromagnetic coupling in Li doped samples. Room temperature ferroelectric hysteresis loops were observed in 8% and 10% Li doped samples. We demonstrated ferroelectric coercivity (remnant polarization) 2.5 kV/cm (0.11 lC/cm 2) and 2.8 kV/cm (0.15 lC/cm 2) for y ¼ 0.08 and y ¼ 0.10 samples. We propose that the mechanism of Li induced ferroelectricity in ZnO is due to indirect dipole interaction via hole carriers. We investigated that if the sample has hole carriers !5.3 Â 10 17 /cc, they can mediate the ferroelectricity. Ferroelectric and ferromagnetic measurements showed that higher electric polarization and larger magnetic moment is attained when the hole concentration is larger and vice versa. Our results confirmed the hole dependent coexistence of ferromagnetic and ferroelectric behavior at room temperature, which provide potential applications for switchable and memory devices. V

Applied Nanoscience, 2013

This is a vital extension of our previously published work. Thermo-responsive copolymer coated su... more This is a vital extension of our previously published work. Thermo-responsive copolymer coated superparamagnetic MnFe 2 O 4 nanoparticles are tested for cell viability and affinity on HeLa carcinoma cells under different conditions. Nanoparticles were loaded with anticancer drug doxorubicin. Composite nanoparticles of average diameter 45 nm were of core-shell structure having magnetic core of about 18 nm. Magnetic hyperthermia effects on cell viability and drug delivery were studied by exposing the cell suspension to high frequency magnetic field, and living cells were quantified using MTT method. There was almost absence of drug release at 37°C. Drug was released at temperatures above lower critical solution temperature (LCST) by magnetic heating. LCST of the thermo-responsive copolymer was observed to be around 39°C. Below this temperature, copolymer was hydrophilic and swelled. But above LCST, copolymer could become hydrophobic, expel water and drug and shrink in volume. Combination of hyperthermia and drug delivery effectively treated cancer cells.

International Nano Letters, 2012

Controlled conduction of magnetic spins is desired for data processing in modern spintronic devic... more Controlled conduction of magnetic spins is desired for data processing in modern spintronic devices. Transition metal-doped ZnO is a potential candidate for this purpose. We studied the effects of cobalt doping on structural, absorbance, and magnetic properties of ZnO nano-particles. Different compositions (Zn0.99Co0.1O, Zn0.97Co0.3O, and Zn0.95Co0.5O) of cobalt-doped ZnO were fabricated using metallic chlorides by co-precipitation method. XRD revealed standard ZnO wurtzite crystal structure without lattice distortion due to impurities but showed presence of additional phases at higher doping ratios. Fourier transformed infrared spectroscopy also confirmed the standard ZnO profiles at lower doping ratios but additional phases at higher doping. Vibrating sample magnetometer showed soft ferromagnetic behavior for low impurity samples and harder ferromagnetic behavior for higher doping at room temperature. A simultaneous differential scanning calorimetry/thermo gravimetric analysis was...

Journal of Magnetism and Magnetic Materials, 2010

Glass ceramics of the composition xZnO Á 25Fe 2 O 3 Á (40 À x)SiO 2 Á 25CaO Á 7P 2 O 5 Á 3Na 2 O ... more Glass ceramics of the composition xZnO Á 25Fe 2 O 3 Á (40 À x)SiO 2 Á 25CaO Á 7P 2 O 5 Á 3Na 2 O were prepared by the melt-quench method using oxy-acetylene flame. Glass-powder compacts were sintered at 1100 1C for 3 h and then rapidly cooled at À 10 1C. X-ray diffraction (XRD) revealed 3 prominent crystalline phases: ZnFe 2 O 4 , CaSiO 3 and Ca 10 (PO 4) 6 (OH) 2. Vibrating sample magnetometer (VSM) data at 10 KOe and 500 Oe showed that saturation magnetization, coercivity and hence hysteresis area increased with the increase in ZnO content. Nano-sized ZnFe 2 O 4 crystallites were of pseudo-single domain structure and thus coercivity increased with the increase in crystallite size. ZnFe 2 O 4 exhibited ferrimagnetism due to the random distribution of Zn 2 + and Fe 3 + cations at tetrahedral A sites and octahedral B sites. This inversion/random distribution of cations was probably due to the surface effects of nano-ZnFe 2 O 4 and rapid cooling of the material from 1100 1C (thus preserving the high temperature state of the random distribution of cations). Calorimetric measurements were carried out using magnetic induction furnace at 500 Oe magnetic field and 400 KHz frequency. The data showed that maximum specific power loss and temperature increase after 2 min were 26 W/g and 37 1C, respectively for the sample containing 10% ZnO. The samples were immersed in simulated body fluid (SBF) for 3 weeks. Scanning electron microscope (SEM), energy dispersive spectroscopy (EDX) and XRD results confirmed the growth of precipitated hydroxyapatite phase after immersion in SBF, suggesting that the ferrimagnetic glass ceramics were bioactive and could bond to the living tissues in physiological environment.

This paper presents a novel hypothesis on the function of massive feedback pathways in mammalian ... more This paper presents a novel hypothesis on the function of massive feedback pathways in mammalian visual systems. We propose that the cortical feature detectors compete not for the right to represent the output at a point, but for exclusive rights to abstract and represent part of the underlying input. Feedback can do this very naturally. A computational model that implements the above idea for the problem of line detection is presented and based on that we suggest a functional role for the thalamo-cortical loop during perception of lines. We show that the model successfully tackles the so called Cross problem. Based on some recent experimental results, we discuss the biological plausibility of our model. We also comment on the relevance of our hypothesis (on the role of feedback) to general sensory information processing and recognition.

Fusion engineering and …, 2001

This paper presents the control system overview, hardware, software and network for Data acquisit... more This paper presents the control system overview, hardware, software and network for Data acquisition and Control system for steady state neutral beam injector (NBIDACS) to be used for heating of plasma in steady state superconducting tokamak (SST-1). The task for NBIDACS is not ...

BJOG: An International Journal …, 2001

Results Women from social classes II and I and women who live in the south of England were more l... more Results Women from social classes II and I and women who live in the south of England were more likely to use hormone replacement therapy independently of a range of socio-demographic factors including education. The adjusted odds ratio for social classes II and I compared ...

Ophthalmology, 2000

Mean IOP was 19.80 mmHg at 8:00 (95% confidence interval [CI], 18.95–20.66 mmHg), 20.38 mmHg at 1... more Mean IOP was 19.80 mmHg at 8:00 (95% confidence interval [CI], 18.95–20.66 mmHg), 20.38 mmHg at 12:00 (95% CI, 19.49–21.26 mmHg), 19.91 mmHg at 4:00 (95% CI, 19.99–21.83 mmHg), and 19.23 mmHg at 8:00 (95% CI, 18.35–20.11 mmHg). Mean CCT was 569.4 ...

We have recently proposed that one way that plant growth-promoting rhizobacteria (PGPR) stimulate... more We have recently proposed that one way that plant growth-promoting rhizobacteria (PGPR) stimulate plant growth is through the activity of the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase, which causes a lowering of plant ethylene levels resulting in longer roots. As part of an effort to understand the role of this enzyme in PGPR, the genes for ACC deaminase from two PGPR, Enterobacter cloacae CAL2 and UW4, have been isolated. These genes are highly homologous to the ACC deaminase genes from Pseudomonas strains 6G5 and F17 and similar to the ACC deaminase gene from Pseudomonas sp. strain ACP. The region downstream (i.e., at the 3'-terminal end) of the strain UW4 ACC deaminase gene has a potential hairpin-like transcription termination site. The regions upstream of the strains UW4 and CAL2 ACC deaminase genes contain putative ribosome-binding sites; however, the promoter sequences have not yet been identified. Southern hybridization experiments suggest that there is a single copy of the ACC deaminase gene in Enterobacter cloacae strains UW4 and CAL2 and that there may be several different types of ACC deaminase genes in different microbes. The cloned ACC deaminase gene can be expressed in Escherichia coli enabling this bacterium to grow on ACC as a sole source of nitrogen and confers upon both Escherichia coli and Pseudomonas spp. strains that are transformed with this gene the ability to promote the elongation of the roots of canola seedlings.Key words: plant growth-promoting rhizobacteria, PGPR, 1-aminocyclopropane-1-carboxylate, ACC, ACC deaminase, ethylene, soil bacteria.