Shoaib Ahmad - Academia.edu (original) (raw)

Papers by Shoaib Ahmad

Journal of Solid Tumors, 2012

Renal cell carcinoma (RCC) has unpredictable and diverse behavior. The classic triad of hematuria... more Renal cell carcinoma (RCC) has unpredictable and diverse behavior. The classic triad of hematuria, loin pain and abdominal mass is uncommon. About, 25%-30% of patients are found to have metastases at the time of diagnosis. Bones, lungs, liver and brain are the frequent sites of metastases. RCC with metastasis to the thyroid gland is rarest manifestation. We report a case of 40 years old male who underwent radical nephectomy for localized RCC seven years back, now presented with swelling in neck which was suspected as thyroid malignancy; subsequently was confirmed as metastatic RCC following excisional biopsy and was treated with surgical resection.

Journal of Solid Tumors, 2012

The bladder cancer usually metastasizes to regional pelvic lymph nodes, lungs, liver and bones. M... more The bladder cancer usually metastasizes to regional pelvic lymph nodes, lungs, liver and bones. Metastasis to non-regional lymph nodes especially cervical lymph nodes is extremely rare presentation. Metastasis to head and neck region is associated with poor prognosis and low survival rate. Here-in we report a case cervical lymph node metastasis in patient with muscle invasive bladder cancer.

Journal of Solid Tumors, 2012

Renal cell carcinoma (RCC) has unpredictable and diverse behavior. The classic triad of hematuria... more Renal cell carcinoma (RCC) has unpredictable and diverse behavior. The classic triad of hematuria, loin pain and abdominal mass is uncommon. About 25%-30% of patients are found to have metastases at the time of diagnosis. Bones, lungs, liver and brain are the frequent sites of metastases. RCC with metastasis to the oral cavity is rarest manifestation. We report a case of 35 years old male who underwent radical nephrectomy for localized RCC six years back, now presented with mass in the base of tongue which was suspected as carcinoma of tongue; subsequently was confirmed as metastatic RCC following excisional biopsy and was treated with intra-oral electron radiation therapy.

Journal of Solid Tumors, 2011

Abstract Sunitinib (Sutent®: Pfizer, New York, NY, USA) is an oral multi-targeted tyrosine kinase... more Abstract Sunitinib (Sutent®: Pfizer, New York, NY, USA) is an oral multi-targeted tyrosine kinase inhibitor approved for first-line treatment of metastatic renal cell carcinoma (mRCC) and imatinib-resistant metastatic gastrointestinal stromal tumors (GIST). Common non ...

Le Journal De Physique Colloques, 1987

Le Journal De Physique Colloques, 1987

Philosophical Magazine A-physics of Condensed Matter Structure Defects and Mechanical Properties - PHIL MAG A, 1988

The synchrotron radiation source at the Daresbury Laboratory, Science and Engineering Research Co... more The synchrotron radiation source at the Daresbury Laboratory, Science and Engineering Research Council, has been used to obtain white X-radiation topographs of high-quality single crystals of ice with exposure times of about 20 s. Sequences of topographs show the motion of individual dislocations under stress in the very early stages of plastic deformation at temperatures from −10 to −35°C. Glide on the basal plane appears to be limited by a Peierls barrier in the screw and 60° orientations. Edge, but not screw, dislocations on non-basal planes glide faster than dislocations on the basal plane and act as sources of dislocation multiplication. The velocities of both basal and non-basal dislocations are found to be linear functions of stress. Much recovery occurs on the time scale of previous experiments to measure dislocation velocities. The implications of the observations for theories of dislocation mobility are discussed.

Philosophical Magazine A-physics of Condensed Matter Structure Defects and Mechanical Properties - PHIL MAG A, 1988

The synchrotron radiation source at the Daresbury Laboratory, Science and Engineering Research Co... more The synchrotron radiation source at the Daresbury Laboratory, Science and Engineering Research Council, has been used to obtain white X-radiation topographs of high-quality single crystals of ice with exposure times of about 20 s. Sequences of topographs show the motion of individual dislocations under stress in the very early stages of plastic deformation at temperatures from −10 to −35°C. Glide on the basal plane appears to be limited by a Peierls barrier in the screw and 60° orientations. Edge, but not screw, dislocations on non-basal planes glide faster than dislocations on the basal plane and act as sources of dislocation multiplication. The velocities of both basal and non-basal dislocations are found to be linear functions of stress. Much recovery occurs on the time scale of previous experiments to measure dislocation velocities. The implications of the observations for theories of dislocation mobility are discussed.

Nanotechnology, 2005

The spherical curvature induced by pentagons in corannulenes and hexagonal sheets is shown to be ... more The spherical curvature induced by pentagons in corannulenes and hexagonal sheets is shown to be the basic constituent that controls the growth of fullerenes and single-walled carbon nanotubes (SWNTs) in soot forming and carbon vapour environments. Formation of the initial ring of five or six atoms is the essential step which with the addition of further pentagons and hexagons determines whether a spinning fullerene is to be formed or the cap that lifts up and leads to the formation of an SWNT. A continuum elastic model is developed to determine the criteria for the growth of these structures. The observed dominance of the growth of 14 Å diameter armchair SWNTs in sooting and carbonaceous environments is explained by using the nanoelastic model of C shells.

Nanotechnology, 2005

The spherical curvature induced by pentagons in corannulenes and hexagonal sheets is shown to be ... more The spherical curvature induced by pentagons in corannulenes and hexagonal sheets is shown to be the basic constituent that controls the growth of fullerenes and single-walled carbon nanotubes (SWNTs) in soot forming and carbon vapour environments. Formation of the initial ring of five or six atoms is the essential step which with the addition of further pentagons and hexagons determines whether a spinning fullerene is to be formed or the cap that lifts up and leads to the formation of an SWNT. A continuum elastic model is developed to determine the criteria for the growth of these structures. The observed dominance of the growth of 14 Å diameter armchair SWNTs in sooting and carbonaceous environments is explained by using the nanoelastic model of C shells.

Applied Physics Letters, 1999

Diagnostics of the carbon atoms, ions, and clusters C m 0,Ϯ (mр4) sputtered from a graphite surfa... more Diagnostics of the carbon atoms, ions, and clusters C m 0,Ϯ (mр4) sputtered from a graphite surface under 10 keV Xe ϩ bombardment reveals the presence of neutral C m 0 and positively charged C m ϩ species in the photoemission spectra. The complete absence of C m ϩ in the mass spectra by a velocity analyzer is supplemented by the presence of the negatively charged C m Ϫ . The velocity spectra are dominated by C and C 2 Ϫ with peaks due to C 3 Ϫ and C 4 Ϫ . These results may help us to understand the contribution of neutral and charged species in the heavy-ion sputtering of graphite and the energetics of regenerative soot.

Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2000

An E;B velocity "lter is described that has been used for the detection and diagnostics of large ... more An E;B velocity "lter is described that has been used for the detection and diagnostics of large carbon clusters C K (m410). The velocity and momentum analyses are compared for our special experimental arrangement. We describe the variability of the resolving power of our compact velocity "lter as the main advantage over other comparable mass analysis techniques.

European Physical Journal D, 2002

The mechanisms and processes of the formation of the regenerative soot in a graphite hollow catho... more The mechanisms and processes of the formation of the regenerative soot in a graphite hollow cathode discharge that produces and emits carbon clusters are presented. Mass spectrometry with a specially designed E×B velocity filter analyzes the entire range of the charged clusters from C 1 to ∼C 4300. The state of the carbon vapour within the source is evaluated by using the characteristic line emissions from the carbonaceous discharge whose formative mechanisms depend upon the kinetic and potential sputtering of the sooted cathode. The carbonaceous discharge generates atomic and ionic C and its clusters C m (m≥ 2), noble gas metastable atoms and ions, energetic electrons and photons in the cavity of the graphite hollow cathode. The parameters of soot formation and its recycling depend critically on the discharge parameters, the geometry of the hollow cathode and 3D profile of the cusp magnetic field contours.

Physics Letters A, 1999

Ž 4 . Laboratory formation of large carbon clusters C m F 10 in carbonaceous plasmas is studied b... more Ž 4 . Laboratory formation of large carbon clusters C m F 10 in carbonaceous plasmas is studied by using a specially m designed ion source. Carbon is introduced into the glow discharge plasma by graphite sputtering. Regenerative sooting plasma creates clustering environment. Velocity spectra of the extracted clusters indicates the mechanisms operating in the soot. q

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2011

We report the ablation of fullerite films deposited on metallic substrates with 3 keV electron pu... more We report the ablation of fullerite films deposited on metallic substrates with 3 keV electron pulses generated in a specially designed pulsed discharge tube. During ablation the fragmented species were detected by emission spectroscopy. The emission spectra of C 2 and C 1 ⁄ (CII) provide the signatures of C 60 fragmentation. The vibrational temperature of the C 2 emitted from the ablated fullerite is 12,700±1160Kcomparedwith12,700 ± 1160 K compared with 12,700±1160Kcomparedwith18,230 ± 1150 K for the graphite sample under similar conditions. The fullerite films were produced by vacuum sublimation on Aluminum, Iron and Copper substrates and characterized by Atomic force microscope, X-ray diffraction; Raman and Fourier transform infrared spectroscopy. The comparisons of electron ablation of fullerite films with that of graphite show the similarities and differences of carbon bonding in the caged structure of C 60 with that of the planar graphene sheets of graphite.

Physical Review E, 2001

Mass spectrometry and photoemission spectroscopy of a graphite hollow cathode source identify the... more Mass spectrometry and photoemission spectroscopy of a graphite hollow cathode source identify the parameters of the transition from the C 3 -dominated discharge to the sooting plasma. The transition is a function of the shape and profile of a special cusp magnetic field B z (r,), the geometry of the source, the discharge current, and pressure. Characteristic atomic and molecular emission lines and bands in the C 3 discharge transform into broad bands emitted by the excited soot. We identify four prominent emission bands between 300-400 nm to be the hallmark of the sooting plasma.

Journal of Solid Tumors, 2012

Renal cell carcinoma (RCC) has unpredictable and diverse behavior. The classic triad of hematuria... more Renal cell carcinoma (RCC) has unpredictable and diverse behavior. The classic triad of hematuria, loin pain and abdominal mass is uncommon. About, 25%-30% of patients are found to have metastases at the time of diagnosis. Bones, lungs, liver and brain are the frequent sites of metastases. RCC with metastasis to the thyroid gland is rarest manifestation. We report a case of 40 years old male who underwent radical nephectomy for localized RCC seven years back, now presented with swelling in neck which was suspected as thyroid malignancy; subsequently was confirmed as metastatic RCC following excisional biopsy and was treated with surgical resection.

Journal of Solid Tumors, 2012

The bladder cancer usually metastasizes to regional pelvic lymph nodes, lungs, liver and bones. M... more The bladder cancer usually metastasizes to regional pelvic lymph nodes, lungs, liver and bones. Metastasis to non-regional lymph nodes especially cervical lymph nodes is extremely rare presentation. Metastasis to head and neck region is associated with poor prognosis and low survival rate. Here-in we report a case cervical lymph node metastasis in patient with muscle invasive bladder cancer.

Journal of Solid Tumors, 2012

Renal cell carcinoma (RCC) has unpredictable and diverse behavior. The classic triad of hematuria... more Renal cell carcinoma (RCC) has unpredictable and diverse behavior. The classic triad of hematuria, loin pain and abdominal mass is uncommon. About 25%-30% of patients are found to have metastases at the time of diagnosis. Bones, lungs, liver and brain are the frequent sites of metastases. RCC with metastasis to the oral cavity is rarest manifestation. We report a case of 35 years old male who underwent radical nephrectomy for localized RCC six years back, now presented with mass in the base of tongue which was suspected as carcinoma of tongue; subsequently was confirmed as metastatic RCC following excisional biopsy and was treated with intra-oral electron radiation therapy.

Journal of Solid Tumors, 2011

Abstract Sunitinib (Sutent®: Pfizer, New York, NY, USA) is an oral multi-targeted tyrosine kinase... more Abstract Sunitinib (Sutent®: Pfizer, New York, NY, USA) is an oral multi-targeted tyrosine kinase inhibitor approved for first-line treatment of metastatic renal cell carcinoma (mRCC) and imatinib-resistant metastatic gastrointestinal stromal tumors (GIST). Common non ...

Le Journal De Physique Colloques, 1987

Le Journal De Physique Colloques, 1987

Philosophical Magazine A-physics of Condensed Matter Structure Defects and Mechanical Properties - PHIL MAG A, 1988

The synchrotron radiation source at the Daresbury Laboratory, Science and Engineering Research Co... more The synchrotron radiation source at the Daresbury Laboratory, Science and Engineering Research Council, has been used to obtain white X-radiation topographs of high-quality single crystals of ice with exposure times of about 20 s. Sequences of topographs show the motion of individual dislocations under stress in the very early stages of plastic deformation at temperatures from −10 to −35°C. Glide on the basal plane appears to be limited by a Peierls barrier in the screw and 60° orientations. Edge, but not screw, dislocations on non-basal planes glide faster than dislocations on the basal plane and act as sources of dislocation multiplication. The velocities of both basal and non-basal dislocations are found to be linear functions of stress. Much recovery occurs on the time scale of previous experiments to measure dislocation velocities. The implications of the observations for theories of dislocation mobility are discussed.

Philosophical Magazine A-physics of Condensed Matter Structure Defects and Mechanical Properties - PHIL MAG A, 1988

The synchrotron radiation source at the Daresbury Laboratory, Science and Engineering Research Co... more The synchrotron radiation source at the Daresbury Laboratory, Science and Engineering Research Council, has been used to obtain white X-radiation topographs of high-quality single crystals of ice with exposure times of about 20 s. Sequences of topographs show the motion of individual dislocations under stress in the very early stages of plastic deformation at temperatures from −10 to −35°C. Glide on the basal plane appears to be limited by a Peierls barrier in the screw and 60° orientations. Edge, but not screw, dislocations on non-basal planes glide faster than dislocations on the basal plane and act as sources of dislocation multiplication. The velocities of both basal and non-basal dislocations are found to be linear functions of stress. Much recovery occurs on the time scale of previous experiments to measure dislocation velocities. The implications of the observations for theories of dislocation mobility are discussed.

Nanotechnology, 2005

The spherical curvature induced by pentagons in corannulenes and hexagonal sheets is shown to be ... more The spherical curvature induced by pentagons in corannulenes and hexagonal sheets is shown to be the basic constituent that controls the growth of fullerenes and single-walled carbon nanotubes (SWNTs) in soot forming and carbon vapour environments. Formation of the initial ring of five or six atoms is the essential step which with the addition of further pentagons and hexagons determines whether a spinning fullerene is to be formed or the cap that lifts up and leads to the formation of an SWNT. A continuum elastic model is developed to determine the criteria for the growth of these structures. The observed dominance of the growth of 14 Å diameter armchair SWNTs in sooting and carbonaceous environments is explained by using the nanoelastic model of C shells.

Nanotechnology, 2005

The spherical curvature induced by pentagons in corannulenes and hexagonal sheets is shown to be ... more The spherical curvature induced by pentagons in corannulenes and hexagonal sheets is shown to be the basic constituent that controls the growth of fullerenes and single-walled carbon nanotubes (SWNTs) in soot forming and carbon vapour environments. Formation of the initial ring of five or six atoms is the essential step which with the addition of further pentagons and hexagons determines whether a spinning fullerene is to be formed or the cap that lifts up and leads to the formation of an SWNT. A continuum elastic model is developed to determine the criteria for the growth of these structures. The observed dominance of the growth of 14 Å diameter armchair SWNTs in sooting and carbonaceous environments is explained by using the nanoelastic model of C shells.

Applied Physics Letters, 1999

Diagnostics of the carbon atoms, ions, and clusters C m 0,Ϯ (mр4) sputtered from a graphite surfa... more Diagnostics of the carbon atoms, ions, and clusters C m 0,Ϯ (mр4) sputtered from a graphite surface under 10 keV Xe ϩ bombardment reveals the presence of neutral C m 0 and positively charged C m ϩ species in the photoemission spectra. The complete absence of C m ϩ in the mass spectra by a velocity analyzer is supplemented by the presence of the negatively charged C m Ϫ . The velocity spectra are dominated by C and C 2 Ϫ with peaks due to C 3 Ϫ and C 4 Ϫ . These results may help us to understand the contribution of neutral and charged species in the heavy-ion sputtering of graphite and the energetics of regenerative soot.

Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2000

An E;B velocity "lter is described that has been used for the detection and diagnostics of large ... more An E;B velocity "lter is described that has been used for the detection and diagnostics of large carbon clusters C K (m410). The velocity and momentum analyses are compared for our special experimental arrangement. We describe the variability of the resolving power of our compact velocity "lter as the main advantage over other comparable mass analysis techniques.

European Physical Journal D, 2002

The mechanisms and processes of the formation of the regenerative soot in a graphite hollow catho... more The mechanisms and processes of the formation of the regenerative soot in a graphite hollow cathode discharge that produces and emits carbon clusters are presented. Mass spectrometry with a specially designed E×B velocity filter analyzes the entire range of the charged clusters from C 1 to ∼C 4300. The state of the carbon vapour within the source is evaluated by using the characteristic line emissions from the carbonaceous discharge whose formative mechanisms depend upon the kinetic and potential sputtering of the sooted cathode. The carbonaceous discharge generates atomic and ionic C and its clusters C m (m≥ 2), noble gas metastable atoms and ions, energetic electrons and photons in the cavity of the graphite hollow cathode. The parameters of soot formation and its recycling depend critically on the discharge parameters, the geometry of the hollow cathode and 3D profile of the cusp magnetic field contours.

Physics Letters A, 1999

Ž 4 . Laboratory formation of large carbon clusters C m F 10 in carbonaceous plasmas is studied b... more Ž 4 . Laboratory formation of large carbon clusters C m F 10 in carbonaceous plasmas is studied by using a specially m designed ion source. Carbon is introduced into the glow discharge plasma by graphite sputtering. Regenerative sooting plasma creates clustering environment. Velocity spectra of the extracted clusters indicates the mechanisms operating in the soot. q

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2011

We report the ablation of fullerite films deposited on metallic substrates with 3 keV electron pu... more We report the ablation of fullerite films deposited on metallic substrates with 3 keV electron pulses generated in a specially designed pulsed discharge tube. During ablation the fragmented species were detected by emission spectroscopy. The emission spectra of C 2 and C 1 ⁄ (CII) provide the signatures of C 60 fragmentation. The vibrational temperature of the C 2 emitted from the ablated fullerite is 12,700±1160Kcomparedwith12,700 ± 1160 K compared with 12,700±1160Kcomparedwith18,230 ± 1150 K for the graphite sample under similar conditions. The fullerite films were produced by vacuum sublimation on Aluminum, Iron and Copper substrates and characterized by Atomic force microscope, X-ray diffraction; Raman and Fourier transform infrared spectroscopy. The comparisons of electron ablation of fullerite films with that of graphite show the similarities and differences of carbon bonding in the caged structure of C 60 with that of the planar graphene sheets of graphite.

Physical Review E, 2001

Mass spectrometry and photoemission spectroscopy of a graphite hollow cathode source identify the... more Mass spectrometry and photoemission spectroscopy of a graphite hollow cathode source identify the parameters of the transition from the C 3 -dominated discharge to the sooting plasma. The transition is a function of the shape and profile of a special cusp magnetic field B z (r,), the geometry of the source, the discharge current, and pressure. Characteristic atomic and molecular emission lines and bands in the C 3 discharge transform into broad bands emitted by the excited soot. We identify four prominent emission bands between 300-400 nm to be the hallmark of the sooting plasma.