Muhammad Alam - Academia.edu (original) (raw)

Papers by Muhammad Alam

Fems Microbiology Letters, 2002

Seawater and organic material (live and/or dead matter deposited on any substratum submersed in s... more Seawater and organic material (live and/or dead matter deposited on any substratum submersed in seawater) were collected during the cool weather season from a coast of the Seto-Inland Sea, Japan, and analyzed to determine Vibrio parahaemolyticus densities and the occurrence of pathogenic strains, defined as those possessing tdh and/or trh genes by the polymerase chain reaction (PCR), using isolated DNA from enrichment culture of the samples. About 95% of the samples were positive for V. parahaemolyticus (with densities of 3 to >1400 cells per 100 ml water or 10 g organic samples) by the most-probable-number (MPN)-PCR technique with species-specific toxR primers, but only 40% were positive by the conventional MPN-culture technique (with densities ranging from 3 to 240 cells per 100 ml water or 10 g organics). Furthermore, the tdh and trh genes were positive in 55% and 20% of samples, respectively, by the MPN-PCR technique. No tdh and trh gene-positive strains were isolated by the conventional MPN-culture procedure. The difference in detection between the MPN-culture and the MPN-PCR techniques appeared to be significant and may be attributed to different detection sensitivities and other factors.

IEEE Transactions on Electron Devices, 1993

Page 1. IEEE TRANSACTIONS ON ELECTRON DkVICtS. VOL JO, NO 1. APRIL l W 3 733 A Critical Examinati... more Page 1. IEEE TRANSACTIONS ON ELECTRON DkVICtS. VOL JO, NO 1. APRIL l W 3 733 A Critical Examination of the Assumptions Underlying Macroscopic Transport Equations for Silicon Devices Mark A. Stettler, Muhammad ...

MOSFETs is one of the major reliability concerns in sub-100nm technologies. So far, studies of NB... more MOSFETs is one of the major reliability concerns in sub-100nm technologies. So far, studies of NBTI and its impact on circuit performance have assumed an average behavior of the degradation process. However, in very short channel devices, finite number of Si-H bonds in the channel can induce a statistical random variation of the degradation process. This results in significant random Vt variations in PMOS transistor. The NBTI induced variation depends on operating temperature and the effective stress period for the specific device. In this paper, we analyze the impact of stochastic temporal NBTI variations and propose a compact circuit level Vt model. Using the proposed model, we show how temporal Vt variations can affect the lifetime performance of different circuit topologies including 6T SRAM cell and random combinational logic circuits.

IEEE Transactions on Electron Devices, 2002

Based on the theory of soft and hard breakdown established in Part I of this paper [10], we now s... more Based on the theory of soft and hard breakdown established in Part I of this paper [10], we now study the principles of area, thickness, voltage, and circuit configuration dependence of hard and soft breakdown. These scaling principles allow us to conclude that breakdown in ultrathin oxides stressed at operating voltages (1.0-1.5 V) can never be hard, which should allow a more relaxed reliability specification for these oxides.

Nature Nanotechnology, 2007

Single-walled carbon nanotubes (SWNTs) have many exceptional electronic properties. Realizing the... more Single-walled carbon nanotubes (SWNTs) have many exceptional electronic properties. Realizing the full potential of SWNTs in realistic electronic systems requires a scalable approach to device and circuit integration. We report the use of dense, perfectly aligned arrays of long, perfectly linear SWNTs as an effective thin-film semiconductor suitable for integration into transistors and other classes of electronic devices. The large number of SWNTs enable excellent device-level performance characteristics and good device-to-device uniformity, even with SWNTs that are electronically heterogeneous. Measurements on p-and n-channel transistors that involve as many as 2,100 SWNTs reveal device-level mobilities and scaled transconductances approaching 1,000 cm 2 V 21 s 21 and 3,000 S m 21 , respectively, and with current outputs of up to 1 A in devices that use interdigitated electrodes. PMOS and CMOS logic gates and mechanically flexible transistors on plastic provide examples of devices that can be formed with this approach. Collectively, these results may represent a route to large-scale integrated nanotube electronics.

IEEE Transactions on Device and Materials Reliability, 2008

Abstract—In this paper, a focused review is made of our pre-viously reported (2002–2007) work on ... more Abstract—In this paper, a focused review is made of our pre-viously reported (2002–2007) work on negative bias temperature instability (NBTI) measurement and analysis. Using suitable cross-reference to other published work, the impacts of stress condition, characterization ...

American Journal of Kidney Diseases, 2003

The importance of iron in injury is derived from the ease with which iron is reversibly oxidized ... more The importance of iron in injury is derived from the ease with which iron is reversibly oxidized and reduced and thus able to participate in the generation of powerful oxidant species, such as hydroxyl radical, and in lipid peroxidation. There is compelling mechanistic evidence for the potential role of iron in atherosclerosis: the role of iron in oxidizing low-density lipoprotein (LDL), iron chelators prevent endothelial cell damage by oxidized LDL, the ability of iron to cause endothelial cell damage, and iron chelators prevent endothelial cell dysfunction and vascular smooth muscle proliferation. In addition to these effects, important in atherosclerosis, ample experimental evidence suggests a role of iron in myocardial reperfusion injury. Epidemiological data have provided conflicting results, with several studies reporting an association between iron stores and progression of carotid atherosclerosis or acute myocardial infarction, whereas others argue against such an association. However, the availability of catalytic iron and the susceptibility of an individual may be more important than overall iron body status. Studies that address these issues, as well as those designed to establish cause and effect, are needed before one can reach meaningful conclusions about the role of iron in atherosclerosis and the therapeutic implications for patients. Am J Kidney Dis 41(S1):80-83.

Kidney International, 2001

studies directly comparing two modalities are required to define Sustained low-efficiency dialysi... more studies directly comparing two modalities are required to define Sustained low-efficiency dialysis for critically ill patients requirthe exact role for SLED in this setting. ing renal replacement therapy.

IEEE Transactions on Electron Devices, 2007

Biosensors based on silicon nanowires (Si-NWs) promise highly sensitive dynamic label-free electr... more Biosensors based on silicon nanowires (Si-NWs) promise highly sensitive dynamic label-free electrical detection of biomolecules. Despite the tremendous potential and promising experimental results, the fundamental mechanism of electrical sensing of biomolecules and the design considerations of NW sensors remain poorly understood. In this paper, we discuss the prospects and challenges of biomolecule detection using Si-NW biosensors as a function of device parameters, fluidic environment, charge polarity of biomolecules, etc., and refer to experimental results in literature to support the nonintuitive predictions wherever possible. Our results indicate that the design of Si nanobiosensor is nontrivial and as such, only careful optimization supported by numerical simulation would ensure optimal sensor performance.

Fems Microbiology Letters, 2002

Seawater and organic material (live and/or dead matter deposited on any substratum submersed in s... more Seawater and organic material (live and/or dead matter deposited on any substratum submersed in seawater) were collected during the cool weather season from a coast of the Seto-Inland Sea, Japan, and analyzed to determine Vibrio parahaemolyticus densities and the occurrence of pathogenic strains, defined as those possessing tdh and/or trh genes by the polymerase chain reaction (PCR), using isolated DNA from enrichment culture of the samples. About 95% of the samples were positive for V. parahaemolyticus (with densities of 3 to >1400 cells per 100 ml water or 10 g organic samples) by the most-probable-number (MPN)-PCR technique with species-specific toxR primers, but only 40% were positive by the conventional MPN-culture technique (with densities ranging from 3 to 240 cells per 100 ml water or 10 g organics). Furthermore, the tdh and trh genes were positive in 55% and 20% of samples, respectively, by the MPN-PCR technique. No tdh and trh gene-positive strains were isolated by the conventional MPN-culture procedure. The difference in detection between the MPN-culture and the MPN-PCR techniques appeared to be significant and may be attributed to different detection sensitivities and other factors.

IEEE Transactions on Electron Devices, 1993

Page 1. IEEE TRANSACTIONS ON ELECTRON DkVICtS. VOL JO, NO 1. APRIL l W 3 733 A Critical Examinati... more Page 1. IEEE TRANSACTIONS ON ELECTRON DkVICtS. VOL JO, NO 1. APRIL l W 3 733 A Critical Examination of the Assumptions Underlying Macroscopic Transport Equations for Silicon Devices Mark A. Stettler, Muhammad ...

MOSFETs is one of the major reliability concerns in sub-100nm technologies. So far, studies of NB... more MOSFETs is one of the major reliability concerns in sub-100nm technologies. So far, studies of NBTI and its impact on circuit performance have assumed an average behavior of the degradation process. However, in very short channel devices, finite number of Si-H bonds in the channel can induce a statistical random variation of the degradation process. This results in significant random Vt variations in PMOS transistor. The NBTI induced variation depends on operating temperature and the effective stress period for the specific device. In this paper, we analyze the impact of stochastic temporal NBTI variations and propose a compact circuit level Vt model. Using the proposed model, we show how temporal Vt variations can affect the lifetime performance of different circuit topologies including 6T SRAM cell and random combinational logic circuits.

IEEE Transactions on Electron Devices, 2002

Based on the theory of soft and hard breakdown established in Part I of this paper [10], we now s... more Based on the theory of soft and hard breakdown established in Part I of this paper [10], we now study the principles of area, thickness, voltage, and circuit configuration dependence of hard and soft breakdown. These scaling principles allow us to conclude that breakdown in ultrathin oxides stressed at operating voltages (1.0-1.5 V) can never be hard, which should allow a more relaxed reliability specification for these oxides.

Nature Nanotechnology, 2007

Single-walled carbon nanotubes (SWNTs) have many exceptional electronic properties. Realizing the... more Single-walled carbon nanotubes (SWNTs) have many exceptional electronic properties. Realizing the full potential of SWNTs in realistic electronic systems requires a scalable approach to device and circuit integration. We report the use of dense, perfectly aligned arrays of long, perfectly linear SWNTs as an effective thin-film semiconductor suitable for integration into transistors and other classes of electronic devices. The large number of SWNTs enable excellent device-level performance characteristics and good device-to-device uniformity, even with SWNTs that are electronically heterogeneous. Measurements on p-and n-channel transistors that involve as many as 2,100 SWNTs reveal device-level mobilities and scaled transconductances approaching 1,000 cm 2 V 21 s 21 and 3,000 S m 21 , respectively, and with current outputs of up to 1 A in devices that use interdigitated electrodes. PMOS and CMOS logic gates and mechanically flexible transistors on plastic provide examples of devices that can be formed with this approach. Collectively, these results may represent a route to large-scale integrated nanotube electronics.

IEEE Transactions on Device and Materials Reliability, 2008

Abstract—In this paper, a focused review is made of our pre-viously reported (2002–2007) work on ... more Abstract—In this paper, a focused review is made of our pre-viously reported (2002–2007) work on negative bias temperature instability (NBTI) measurement and analysis. Using suitable cross-reference to other published work, the impacts of stress condition, characterization ...

American Journal of Kidney Diseases, 2003

The importance of iron in injury is derived from the ease with which iron is reversibly oxidized ... more The importance of iron in injury is derived from the ease with which iron is reversibly oxidized and reduced and thus able to participate in the generation of powerful oxidant species, such as hydroxyl radical, and in lipid peroxidation. There is compelling mechanistic evidence for the potential role of iron in atherosclerosis: the role of iron in oxidizing low-density lipoprotein (LDL), iron chelators prevent endothelial cell damage by oxidized LDL, the ability of iron to cause endothelial cell damage, and iron chelators prevent endothelial cell dysfunction and vascular smooth muscle proliferation. In addition to these effects, important in atherosclerosis, ample experimental evidence suggests a role of iron in myocardial reperfusion injury. Epidemiological data have provided conflicting results, with several studies reporting an association between iron stores and progression of carotid atherosclerosis or acute myocardial infarction, whereas others argue against such an association. However, the availability of catalytic iron and the susceptibility of an individual may be more important than overall iron body status. Studies that address these issues, as well as those designed to establish cause and effect, are needed before one can reach meaningful conclusions about the role of iron in atherosclerosis and the therapeutic implications for patients. Am J Kidney Dis 41(S1):80-83.

Kidney International, 2001

studies directly comparing two modalities are required to define Sustained low-efficiency dialysi... more studies directly comparing two modalities are required to define Sustained low-efficiency dialysis for critically ill patients requirthe exact role for SLED in this setting. ing renal replacement therapy.

IEEE Transactions on Electron Devices, 2007

Biosensors based on silicon nanowires (Si-NWs) promise highly sensitive dynamic label-free electr... more Biosensors based on silicon nanowires (Si-NWs) promise highly sensitive dynamic label-free electrical detection of biomolecules. Despite the tremendous potential and promising experimental results, the fundamental mechanism of electrical sensing of biomolecules and the design considerations of NW sensors remain poorly understood. In this paper, we discuss the prospects and challenges of biomolecule detection using Si-NW biosensors as a function of device parameters, fluidic environment, charge polarity of biomolecules, etc., and refer to experimental results in literature to support the nonintuitive predictions wherever possible. Our results indicate that the design of Si nanobiosensor is nontrivial and as such, only careful optimization supported by numerical simulation would ensure optimal sensor performance.