We have recently shown that the capillarity-based process for self-assembling particle monolayers... more We have recently shown that the capillarity-based process for self-assembling particle monolayers on fluid-liquid interfaces can be improved by applying an electric field in the direction normal to the interface. The electric field gives rise to repulsive dipole-dipole forces amongst the particles causing them to move apart, and thus allowing them to move freely without blocking one another. The latter is important in the formation of virtually defect-free monolayers with long-range order. In this talk, we present a technique for freezing these expanded monolayers onto the surface of a flexible thin film. The technique involves assembling the monolayer on the interface between a UV-curable resin and a fluid which can be air or another liquid, and then curing the resin by applying UV light. The monolayer becomes embedded on the surface of the solidified resin film.
We show that an external electric field normal to a fluid-fluid interface can be used to self ass... more We show that an external electric field normal to a fluid-fluid interface can be used to self assemble rectangular plates floating on the interface and that the lattice spacing of the monolayer thus formed can be varied by changing the electric field intensity. In our experiments, a ...
Biological particles, such as bacteria and viruses are the major cause for diseases and much of t... more Biological particles, such as bacteria and viruses are the major cause for diseases and much of the current research has been devoted in identifying, and separating them. One way to trap these micro/nano sized particles is by conventional dielectrophoresis, which occurs due to varying electric fields. A much more efficient way is to combine this with the traveling wave dielectrophoresis
Transporting droplets in microfluidic devices can be achieved efficiently by applying a non-unifo... more Transporting droplets in microfluidic devices can be achieved efficiently by applying a non-uniform electric field. While this approach has been successfully used in the past to transport rigid particles, we show here that it can be applied to droplets, particularly those which carry particles on their surface. A droplet not only experiences a net force which transports it, but also
Volume 9: Heat Transfer, Fluid Flows, and Thermal Systems, Parts A, B and C, 2009
It was recently shown by us that particles distributed on the surface of a drop can be concentrat... more It was recently shown by us that particles distributed on the surface of a drop can be concentrated at its poles or the equator by subjecting it to a uniform electric field. In this talk we show that the method can be used to separate particles experiencing positive dielectrophoresis on the surface a drop from those experiencing negative dielectrophoresis. This,
Volume 10: Heat Transfer, Fluid Flows, and Thermal Systems, Parts A, B, and C, 2008
We recently proposed a technique in which an externally applied uniform electric field was used t... more We recently proposed a technique in which an externally applied uniform electric field was used to alter the distribution of particles on the surface of a drop immersed in another immiscible liquid. Particles move along the drop surface to form a ring near the drop equator or collect at the poles depending on their dielectric constant relative to that of the two liquid involved. This motion is due to the dielectrophoretic force that acts upon particles because the electric field on the surface of the drop is non-uniform, despite the fact that the applied electric field is uniform. This technique could be useful to concentrate particles at a drop surface, and also separate two types of particles. In this talk we show that in addition to the dielectrophoretic force the particles also interact with each other via the dipole-dipole interactions to form chains or move away from each other depending on the local direction of the electric field. The regions in which the local electric field is normal to the drop surface (poles), particles move away from each other. On the other hand, where the local direction of electric field is tangential to the drops surface (equator), they form chains that are aligned parallel to the electric field direction.
We have recently shown that the capillarity-based process for self-assembling particle monolayers... more We have recently shown that the capillarity-based process for self-assembling particle monolayers on fluid-liquid interfaces can be improved by applying an electric field in the direction normal to the interface. The electric field gives rise to repulsive dipole-dipole forces amongst the particles causing them to move apart, and thus allowing them to move freely without blocking one another. The latter is important in the formation of virtually defect-free monolayers with long-range order. In this talk, we present a technique for freezing these expanded monolayers onto the surface of a flexible thin film. The technique involves assembling the monolayer on the interface between a UV-curable resin and a fluid which can be air or another liquid, and then curing the resin by applying UV light. The monolayer becomes embedded on the surface of the solidified resin film.
PCR has emerged as a powerful technique for detection of various pathogens including Mycobacteriu... more PCR has emerged as a powerful technique for detection of various pathogens including Mycobacterium tuberculosis. In present study, eighty one samples of lymph node biopsies from clinically suspected cases of tuberculous lymphadenitis were examined for AFB, culture on Löwenstein Jensen medium and simultaneous use of two PCRs targeting IS6110 and MPB64. Positivity with M. tuberculosis culture and AFB was 13.6% and 28.4% respectively. All samples culture positive for nontuberculous mycobacteria were negative by both PCR systems. Higher proportion of positive results were observed with PCR targeting IS6110 by which 56 of 81 (69.1%) samples showed positive results as compared to PCR targeting MPB64 by which 39 of 81 (48.2 %) samples showed positive results. When combined, 63 out of 81 (77.8%) samples were detected positive for M. tuberculosis DNA. However, 7/81 (8.6 %) samples remained negative by IS6110 but positive by MPB64 method. Thus our data suggest that the use of one additional P...
Proceedings of the National Academy of Sciences of the United States of America, Jan 23, 2015
Mycobacterium lepromatosis is an uncultured human pathogen associated with diffuse lepromatous le... more Mycobacterium lepromatosis is an uncultured human pathogen associated with diffuse lepromatous leprosy and a reactional state known as Lucio's phenomenon. By using deep sequencing with and without DNA enrichment, we obtained the near-complete genome sequence of M. lepromatosis present in a skin biopsy from a Mexican patient, and compared it with that of Mycobacterium leprae, which has undergone extensive reductive evolution. The genomes display extensive synteny and are similar in size (∼3.27 Mb). Protein-coding genes share 93% nucleotide sequence identity, whereas pseudogenes are only 82% identical. The events that led to pseudogenization of 50% of the genome likely occurred before divergence from their most recent common ancestor (MRCA), and both M. lepromatosis and M. leprae have since accumulated new pseudogenes or acquired specific deletions. Functional comparisons suggest that M. lepromatosis has lost several enzymes required for amino acid synthesis whereas M. leprae has ...
NPP topology is used to implement 3-level inverter for AC drives. Here 3-level inverter is used t... more NPP topology is used to implement 3-level inverter for AC drives. Here 3-level inverter is used to improve output wave form and also to reduce harmonics torque. This will allow a digital controller or micro-processor based control structure to be implemented. Many inverter topologies are present to implement the 3-level inverter technique. The NPP (natural point piloted) technique, allows lesser
To evaluate the efficacy of ELISA for the detection of IgG antibodies against antigen 85 complex ... more To evaluate the efficacy of ELISA for the detection of IgG antibodies against antigen 85 complex (Ag 85 complex) of Mycobacterium tuberculosis. Children of either sex, 0-18 years of age, attending the outpatient department and admitted in the casualty and wards of the Department of Pediatrics, S.N. Medical College, Agra, were included in present study. The study was carried out on children with pulmonary and CNS tuberculosis along with matching controls (83 cases and 32 controls). Informed consents of their parents or guardians were taken. They were subjected to clinical examination, relevant laboratory investigations, tuberculin test and chest radiograph. Relevant body fluids were subjected to bacteriological tests; ELISA was applied to serum samples for detection of IgG antibodies against antigen 85 complex (Ag85). The result of ELISA was compared with bacteriological tests [Ziehl Neelson (ZN) staining for acid-fast bacilli, culture on Lowenstein Jensen (LJ) medium and culture on BacT/Alert 3D system]. ELISA tests showed a significantly higher sensitivity (59.1%) as compared with LJ medium culture method (19.3%), BacT/Alert 3D system (24.1%) and ZN staining (16.9%) in all patients (p<0.001). Specificity of ELISA test was 71.9%. In view of the convenience, low cost and good sensitivity, ELISA tests have a promising future in the diagnosis of childhood tuberculosis.
Volume 8: Heat Transfer, Fluid Flows, and Thermal Systems, Parts A and B, 2007
We have developed a new direct numerical (DNS) scheme to simulate the motion of dielectric partic... more We have developed a new direct numerical (DNS) scheme to simulate the motion of dielectric particles suspended in a dielectric liquid in uniform and nonuniform electric fields. The motion of particles is tracked using a distributed Lagrange multiplier method (DLM) and the ...
Pyrazinamide (PZA) is an important front line anti-tuberculosis drug because of its sterilizing a... more Pyrazinamide (PZA) is an important front line anti-tuberculosis drug because of its sterilizing activity against semi-dormant tubercle bacilli. In spite of its remarkable role in shortening the treatment duration from 9 months to 6 months when used in combination with Rifampicin and Isoniazid, PZA remains a difficult paradox because of its incompletely understood mode of action and mechanism of resistance. PZA is a nicotinamide analog prodrug which is converted into the active bactericidal form pyrazinoic acid by the bacterial enzyme pyrazinamidase (PZase). PZA does not appear to have a specific cellular target and instead, exerts its bactericidal effect by disrupting the membrane energetics and acidification of cytoplasm. Majority (72-97%) of PZA-resistant isolates of M. tuberculosis exhibit mutations in their pncA gene or upstream area leading to loss of PZase activity. A wide diversity of pncA mutations scattered along the entire length of pncA gene is unique to PZA resistance. H...
1. Indian J Med Res. 2009 Jan;129(1):108-10. Association of mutations in rpsL gene with high degr... more 1. Indian J Med Res. 2009 Jan;129(1):108-10. Association of mutations in rpsL gene with high degree of streptomycin resistance in clinical isolates of Mycobacterium tuberculosis in India. Das R, Gupta P, Singh P, Chauhan DS, Katoch K, Katoch VM. ...
We have recently shown that the capillarity-based process for self-assembling particle monolayers... more We have recently shown that the capillarity-based process for self-assembling particle monolayers on fluid-liquid interfaces can be improved by applying an electric field in the direction normal to the interface. The electric field gives rise to repulsive dipole-dipole forces amongst the particles causing them to move apart, and thus allowing them to move freely without blocking one another. The latter is important in the formation of virtually defect-free monolayers with long-range order. In this talk, we present a technique for freezing these expanded monolayers onto the surface of a flexible thin film. The technique involves assembling the monolayer on the interface between a UV-curable resin and a fluid which can be air or another liquid, and then curing the resin by applying UV light. The monolayer becomes embedded on the surface of the solidified resin film.
We show that an external electric field normal to a fluid-fluid interface can be used to self ass... more We show that an external electric field normal to a fluid-fluid interface can be used to self assemble rectangular plates floating on the interface and that the lattice spacing of the monolayer thus formed can be varied by changing the electric field intensity. In our experiments, a ...
Biological particles, such as bacteria and viruses are the major cause for diseases and much of t... more Biological particles, such as bacteria and viruses are the major cause for diseases and much of the current research has been devoted in identifying, and separating them. One way to trap these micro/nano sized particles is by conventional dielectrophoresis, which occurs due to varying electric fields. A much more efficient way is to combine this with the traveling wave dielectrophoresis
Transporting droplets in microfluidic devices can be achieved efficiently by applying a non-unifo... more Transporting droplets in microfluidic devices can be achieved efficiently by applying a non-uniform electric field. While this approach has been successfully used in the past to transport rigid particles, we show here that it can be applied to droplets, particularly those which carry particles on their surface. A droplet not only experiences a net force which transports it, but also
Volume 9: Heat Transfer, Fluid Flows, and Thermal Systems, Parts A, B and C, 2009
It was recently shown by us that particles distributed on the surface of a drop can be concentrat... more It was recently shown by us that particles distributed on the surface of a drop can be concentrated at its poles or the equator by subjecting it to a uniform electric field. In this talk we show that the method can be used to separate particles experiencing positive dielectrophoresis on the surface a drop from those experiencing negative dielectrophoresis. This,
Volume 10: Heat Transfer, Fluid Flows, and Thermal Systems, Parts A, B, and C, 2008
We recently proposed a technique in which an externally applied uniform electric field was used t... more We recently proposed a technique in which an externally applied uniform electric field was used to alter the distribution of particles on the surface of a drop immersed in another immiscible liquid. Particles move along the drop surface to form a ring near the drop equator or collect at the poles depending on their dielectric constant relative to that of the two liquid involved. This motion is due to the dielectrophoretic force that acts upon particles because the electric field on the surface of the drop is non-uniform, despite the fact that the applied electric field is uniform. This technique could be useful to concentrate particles at a drop surface, and also separate two types of particles. In this talk we show that in addition to the dielectrophoretic force the particles also interact with each other via the dipole-dipole interactions to form chains or move away from each other depending on the local direction of the electric field. The regions in which the local electric field is normal to the drop surface (poles), particles move away from each other. On the other hand, where the local direction of electric field is tangential to the drops surface (equator), they form chains that are aligned parallel to the electric field direction.
We have recently shown that the capillarity-based process for self-assembling particle monolayers... more We have recently shown that the capillarity-based process for self-assembling particle monolayers on fluid-liquid interfaces can be improved by applying an electric field in the direction normal to the interface. The electric field gives rise to repulsive dipole-dipole forces amongst the particles causing them to move apart, and thus allowing them to move freely without blocking one another. The latter is important in the formation of virtually defect-free monolayers with long-range order. In this talk, we present a technique for freezing these expanded monolayers onto the surface of a flexible thin film. The technique involves assembling the monolayer on the interface between a UV-curable resin and a fluid which can be air or another liquid, and then curing the resin by applying UV light. The monolayer becomes embedded on the surface of the solidified resin film.
PCR has emerged as a powerful technique for detection of various pathogens including Mycobacteriu... more PCR has emerged as a powerful technique for detection of various pathogens including Mycobacterium tuberculosis. In present study, eighty one samples of lymph node biopsies from clinically suspected cases of tuberculous lymphadenitis were examined for AFB, culture on Löwenstein Jensen medium and simultaneous use of two PCRs targeting IS6110 and MPB64. Positivity with M. tuberculosis culture and AFB was 13.6% and 28.4% respectively. All samples culture positive for nontuberculous mycobacteria were negative by both PCR systems. Higher proportion of positive results were observed with PCR targeting IS6110 by which 56 of 81 (69.1%) samples showed positive results as compared to PCR targeting MPB64 by which 39 of 81 (48.2 %) samples showed positive results. When combined, 63 out of 81 (77.8%) samples were detected positive for M. tuberculosis DNA. However, 7/81 (8.6 %) samples remained negative by IS6110 but positive by MPB64 method. Thus our data suggest that the use of one additional P...
Proceedings of the National Academy of Sciences of the United States of America, Jan 23, 2015
Mycobacterium lepromatosis is an uncultured human pathogen associated with diffuse lepromatous le... more Mycobacterium lepromatosis is an uncultured human pathogen associated with diffuse lepromatous leprosy and a reactional state known as Lucio's phenomenon. By using deep sequencing with and without DNA enrichment, we obtained the near-complete genome sequence of M. lepromatosis present in a skin biopsy from a Mexican patient, and compared it with that of Mycobacterium leprae, which has undergone extensive reductive evolution. The genomes display extensive synteny and are similar in size (∼3.27 Mb). Protein-coding genes share 93% nucleotide sequence identity, whereas pseudogenes are only 82% identical. The events that led to pseudogenization of 50% of the genome likely occurred before divergence from their most recent common ancestor (MRCA), and both M. lepromatosis and M. leprae have since accumulated new pseudogenes or acquired specific deletions. Functional comparisons suggest that M. lepromatosis has lost several enzymes required for amino acid synthesis whereas M. leprae has ...
NPP topology is used to implement 3-level inverter for AC drives. Here 3-level inverter is used t... more NPP topology is used to implement 3-level inverter for AC drives. Here 3-level inverter is used to improve output wave form and also to reduce harmonics torque. This will allow a digital controller or micro-processor based control structure to be implemented. Many inverter topologies are present to implement the 3-level inverter technique. The NPP (natural point piloted) technique, allows lesser
To evaluate the efficacy of ELISA for the detection of IgG antibodies against antigen 85 complex ... more To evaluate the efficacy of ELISA for the detection of IgG antibodies against antigen 85 complex (Ag 85 complex) of Mycobacterium tuberculosis. Children of either sex, 0-18 years of age, attending the outpatient department and admitted in the casualty and wards of the Department of Pediatrics, S.N. Medical College, Agra, were included in present study. The study was carried out on children with pulmonary and CNS tuberculosis along with matching controls (83 cases and 32 controls). Informed consents of their parents or guardians were taken. They were subjected to clinical examination, relevant laboratory investigations, tuberculin test and chest radiograph. Relevant body fluids were subjected to bacteriological tests; ELISA was applied to serum samples for detection of IgG antibodies against antigen 85 complex (Ag85). The result of ELISA was compared with bacteriological tests [Ziehl Neelson (ZN) staining for acid-fast bacilli, culture on Lowenstein Jensen (LJ) medium and culture on BacT/Alert 3D system]. ELISA tests showed a significantly higher sensitivity (59.1%) as compared with LJ medium culture method (19.3%), BacT/Alert 3D system (24.1%) and ZN staining (16.9%) in all patients (p<0.001). Specificity of ELISA test was 71.9%. In view of the convenience, low cost and good sensitivity, ELISA tests have a promising future in the diagnosis of childhood tuberculosis.
Volume 8: Heat Transfer, Fluid Flows, and Thermal Systems, Parts A and B, 2007
We have developed a new direct numerical (DNS) scheme to simulate the motion of dielectric partic... more We have developed a new direct numerical (DNS) scheme to simulate the motion of dielectric particles suspended in a dielectric liquid in uniform and nonuniform electric fields. The motion of particles is tracked using a distributed Lagrange multiplier method (DLM) and the ...
Pyrazinamide (PZA) is an important front line anti-tuberculosis drug because of its sterilizing a... more Pyrazinamide (PZA) is an important front line anti-tuberculosis drug because of its sterilizing activity against semi-dormant tubercle bacilli. In spite of its remarkable role in shortening the treatment duration from 9 months to 6 months when used in combination with Rifampicin and Isoniazid, PZA remains a difficult paradox because of its incompletely understood mode of action and mechanism of resistance. PZA is a nicotinamide analog prodrug which is converted into the active bactericidal form pyrazinoic acid by the bacterial enzyme pyrazinamidase (PZase). PZA does not appear to have a specific cellular target and instead, exerts its bactericidal effect by disrupting the membrane energetics and acidification of cytoplasm. Majority (72-97%) of PZA-resistant isolates of M. tuberculosis exhibit mutations in their pncA gene or upstream area leading to loss of PZase activity. A wide diversity of pncA mutations scattered along the entire length of pncA gene is unique to PZA resistance. H...
1. Indian J Med Res. 2009 Jan;129(1):108-10. Association of mutations in rpsL gene with high degr... more 1. Indian J Med Res. 2009 Jan;129(1):108-10. Association of mutations in rpsL gene with high degree of streptomycin resistance in clinical isolates of Mycobacterium tuberculosis in India. Das R, Gupta P, Singh P, Chauhan DS, Katoch K, Katoch VM. ...
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