Secretion of microneme proteins is essential to Plasmodium invasion but the molecular composition... more Secretion of microneme proteins is essential to Plasmodium invasion but the molecular composition of these secretory organelles remains poorly defined. Here, we describe the first Plasmodium microneme proteome. Purification of micronemes by subcellular fractionation from cultured ookinetes was confirmed by enrichment of known micronemal proteins and electron microscopy. Quantitation of electron micrographs showed >14‐fold microneme enrichment compared to the intact ookinete, such that micronemes comprised 85% of the identifiable organelles in the fraction. Gel LC‐MS/MS of the most abundant protein constituents of the fraction identified three known micronemal proteins chitinase, CTRP, SOAP, together with protein disulphide isomerase (PDI) and HSP70. Highly sensitive MudPIT shotgun proteomics described a total of 345 proteins in the fraction. M1 aminopeptidase and PDI, the former a recognised target of drug development, were both shown to have a micronemal location by IFA. We furt...
Rab proteins are pivotal components of the membrane trafficking machinery in all eukaryotes. Dist... more Rab proteins are pivotal components of the membrane trafficking machinery in all eukaryotes. Distinct Rab proteins locate to specific endomembrane compartments and genomic studies suggest that Rab gene diversity correlates with endomembrane system complexity; for example unicellular organisms generally possess 5-20 Rab family members and the size of the repertoire increases to 25-60 in multicellular systems. Here we report 65 open reading frames from the unicellular protozoan Trichomonas vaginalis that encode distinct Rab proteins (TvRabs), indicating a family with complexity that rivals Homo sapiens in number. The detection of gene transcripts for the majority of these genes and conservation of functional motifs strongly suggests that TvRabs retain functionality and likely roles in membrane trafficking. The T. vaginalis Rab family includes orthologues of the conserved subfamilies, Rab1, Rab5, Rab6, Rab7 and Rab11, but the majority of TvRabs are not represented by orthologues in other systems and includes six novel T. vaginalis specific Rab subfamilies (A-F). The extreme size of the T. vaginalis Rab family, the presence of novel subfamilies plus the divergent nature of many TvRab sequences suggest both the presence of a highly complex endomembrane system within Trichomonas and potentially novel Rab functionality. A family of more than 65 Rab genes in a unicellular genome is unexpected, but may be a requirement for progression though an amoeboid life-cycle phase as both Dictyostelium discoideum and Entamoeba histolytica share with T. vaginalis both an amoeboid life cycle stage and very large Rab gene families.
Investigations were made of lattice imperfections in straight cadmium, iron, and copper whiskers ... more Investigations were made of lattice imperfections in straight cadmium, iron, and copper whiskers by analysing the Laue diffraction photographs of the whiskers recorded with a microfocus X-ray source (focal spot ≈ 40 μm in diameter). Perfect whiskers gave single and sharp Laue spots. The other whiskers gave irregular shaped Laue spots, or Laue spots consisting of two fine components (doublets), or streak like Laue spots. None of the investigated perfect cadmium, iron, and copper whiskers was found to contain an axial screw dislocation. However, the lattice planes of these whiskers were found to be deformed in a complicated way. In imperfect whiskers, each set of parallel lattice planes which gave a Laue doublet, in fact consisted of two sets of parallel lattice planes, slightly misoriented with each other. The angle of misorientation was found to be ≈ 10′ for imperfect Cd whiskers. The angular deformation in the lattice planes of some imperfect Cd whiskers was few degrees of are. In perfect whiskers the lattice perfection did not change appreciably on studying different portions of the whiskers. The lattice imperfection in other whiskers decreased on going from the base towards the tip. On annealing, the Laue spots of perfect whiskers did not show appreciable change in the lattice imperfections. Imperfect whiskers, except the ribbons, showed a decrease in the lattice imperfections on annealing. An increase in the lattice and surface imperfections was observed on annealing the ribbons. The present results can be qualitatively explained by assuming that the growth has taken place at the steps provided by an axial screw dislocation or dislocations, which may themselves have annealed out during growth. Gitterfehler in geraden Kamium-, Eisen- und Kupferwhiskern wurden durch Analyse von Laue-Beugungsbildern der Whisker untersucht, die mit einer Mikrofocus-Rontgenstrahlenquelle (Brennpunkt ≈ 40 μm Durchmesser) aufgenommen wurden. Perfekte Whisker ergaben einzelne und scharfe Laue-Punkte. Die anderen Whisker ergaben irregulare Laue-Punkte oder Laue-Punkte, die aus zwei Feinstrukturkomponenten (Dubletts) bestanden, oder streifenformige Laue-Punkte. Es wurde gefunden, das keiner der unter-suchten perfekten Kadmium-, Eisen- und Kupferwhisker axiale Schraubenversetzungen enthielt, das jedoch die Gitterebenen dieser Whisker in komplizierter Weise deformiert waren. In nichtperfekten Whiskern bestand jeder Satz von parallelen Gitterebenen, der ein Laue-Dublett ergab, tatsachlich aus zwei Satzen paralleler, leicht gegeneinander fehlorientierter Gitterebenen. Als Winkel der Fehlorientierung wurde 10′ fur nichtperfekte Cd-Whisker gefunden. Die Winkeldeformation in den Gitterebenen einiger nichtperfekter Cd-Whisker betrug einige Bogengrade. In perfekten Whiskern wurde bei der Untersuchung verschiedener Abschnitte der Whisker keine wesentlichen Anderungen der Gitterbeschaffenheit gefunden. Die Gitterstorungen in den andern Whiskern nahmen von der Basis zur Spitze hin ab. Nach der Temperung zeigten die Laue-Punkte perfekter Whisker keine wesentlichen Anderungen der Gitterstorungen an. Nichtperfekte Whisker, ausgenommen die Streifen, zeigten nach der Temperung einen Ruckgang der Gitterstorungen. Ein Anstieg der Gitter-und Oberflachenstorungen wurde nach Temperung der Streifen beobachtet. Die Ergebnisse konnen qualitativ durch die Annahme erklart werden, das das Wachstum an den Stufen stattgefunden hat, die durch eine axiale Schraubenversetzung oder Versetzungen gebildet wurden und die selbst wahrend des Wachstums ausgeheilt wurden.
We have cloned a single copy gene from the human parasite Trichomonas vaginalis that encodes a pu... more We have cloned a single copy gene from the human parasite Trichomonas vaginalis that encodes a putative protein of 402 amino acids with ∼35% sequence identity to known ␣ subunits of heterotrimeric G-proteins. It contains the characteristic GTP binding domains G-1 to G-5 with the key residues conserved. The new sequence has an unusual N-terminal extension of ∼70 residues that cannot be aligned to reference G-proteins and which is characterised by proline-rich repeats. To investigate the expression and cellular localisation of the protein we produced specific antisera against a recombinant fusion protein. The antisera recognised a protein of an apparent molecular mass of 51 kDa in protein extracts from T. vaginalis and immunofluorescent microscopy established that the protein is localised to discrete endomembranes. Using a protocol designed to purify mammalian heterotrimeric G-proteins incorporating a GTP␥S binding assay, we isolated two proteins from Trichomonas that are recognised by an heterologous GA/1 antisera raised to a peptide of the conserved G-1 domain of G-protein ␣ subunits. These two proteins have an apparent molecular mass of 61 and 48 kDa, respectively, larger and smaller than the translation product of the cloned gene. Consistent with these results, the GA/1 antisera did not cross-react with the fusion protein produced from the gene we have cloned. These data suggest T. vaginalis possesses more than one heterotrimeric G-protein ␣ subunit. Based on the sequence features of the cloned gene and the biochemical properties of the purified proteins, we suggest that these ␣ subunits are likely to be part of classic heterotrimeric G-protein complexes.
Gobind Sagar Reservoir has been created in Himachal Pradesh, India (31° 25´ N and 76 ° 25´E) by d... more Gobind Sagar Reservoir has been created in Himachal Pradesh, India (31° 25´ N and 76 ° 25´E) by damming River Sutlej at village Bhakra in 1963. The average water spread area of this reservoir is 10,000 hectares. Fishermen have organized themselves in the form of co-operative societies. 26 fisheries co-operative societies were working in Gobind Sagar Reservoir up till 2012. June and July months were observed as closed season, no fishing was done during this period. Proper record maintaining of fish catch was done at different levels by the state fisheries department. Different measures like minimum harvestable size, mesh size regulation and prohibition of illegal fishing etc. were taken for fish conservation. Fishermen were actively involved in the management. Gill nets were used for catching fishes from this reservoir. State fisheries department is realizing 15% royalty of the sold fish. Data used in this paper is about the fish catch during 2006-2012 and were obtained from the stat...
High-resolution X-ray diffraction techniques have been employed successfully to evaluate crystall... more High-resolution X-ray diffraction techniques have been employed successfully to evaluate crystalline quality and long-term stability of coiled membranes. The process of fabrication involves photolithography, implantation by 2 MeV N^{2+} ions inn-type GaAs substrates, followed by selective etching. A five-crystal X-ray diffractometer was employed in (+, −, +) setting with an Mo Kα1exploring beam for high-resolution X-ray diffractometry and topography experiments. The exploring-beam width was reduced to illuminate different segments of the coiled membrane. Diffraction curves recorded from the bulk crystal surrounding the sensor had a half width of 26 arcseconds, whereas the half widths from sensor segments were in the range ∼58 to ∼166 arcseconds. Different segments (particularly vertical ones) were identified from the observed angular separations between different diffraction peaks as well as from the shape of the diffraction peaks. It was found that different segments of the sensor ...
High-resolution X-ray diffractometry, absolute integrated intensity (ρ) measurements, diffuse X-r... more High-resolution X-ray diffractometry, absolute integrated intensity (ρ) measurements, diffuse X-ray scattering (DXS) and infrared (IR) absorption techniques were used to investigate the influence of oxygen on the structural perfection of high purity (resistivity of the order of 4 kΩ cm) float zone (FZ) grown (111) silicon single crystals. A multicrystal diffractometer set in (+,-,-,+) geometry, with Mo Kα1radiation, was employed. From the infrared measurements, the oxygen concentration in the sample was determined to be 1.3 × 1017 atoms cm^{-3}. High-resolution X-ray diffraction curves of the as-grown crystal had half-widths of ∼11 arcsec; the ρ value was 3.5 × 10^{-5} rad. To incorporate oxygen in a controlled manner into the specimens, they were annealed under dry oxygen ambient for 8 h in the temperature range 573–1373 K (in eight steps). Up to 723 K there was no appreciable change in oxygen content or in the degree of perfection. Annealing at temperatures (AT) > 873 K resulte...
... Phys., vol. 71, p. 4589, 1992. Discharge Treatment of W-Si System for Silicidation Awatar Sin... more ... Phys., vol. 71, p. 4589, 1992. Discharge Treatment of W-Si System for Silicidation Awatar Singh, PD Vyas, W. S. Khokle, Chatar Singh, and K. La1 ... The re-A. Singh, PD Vyas, and W. S. Khokle are with CEERI, Pilani, Raj. C. Singh is with ITMMEC, ITT Delhi, Delhi, India. ...
READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE. https://nrc-publications.can... more READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE. https://nrc-publications.canada.ca/eng/copyright Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à
Real structure together with composition and elemental purity of single crystals controls their p... more Real structure together with composition and elemental purity of single crystals controls their properties. This paper reviews recent work carried out at the National Physical Laboratory on application of high resolution X-ray diffractometry, topography and diffuse X-ray scattering for direct observation and characterization of real structure of single crystals of silicon, gallium arsenide, diamond and LiNbO 3. A series of six multicrysta! X-ray diffractometers have been designed, developed and fabricated indigenously. The most versatile of these systems is a five crystal X-ray diffractometer with state-of-the-art level resolution. These techniques and equipments have been applied in studying several interesting problems. Even in dislocation-free crystals of silicon, remarkable differences in the defect structure have been observed if the growth method was changed from float zone to Czochralski. Study of effect of externally applied electric fields and ion implantation on real structure of crystals has yielded interesting results. Images of 'filaments' which show nonhomogeneous distribution of electric current through semiconductors and insulators have been recorded for the first time in high resolution traverse topographs. Diffracted X-ray intensities could be modified by externally applied electric fields. It has been shown that implantation of BF~ ions in silicon for producing shallow junctions does not produce homogeneous distribution of boron. The impurity is partially in clustered form. Biaxial stress introduced by thin depositions in substrate crystals are of considerable applied concern. The. value and nature of stress have been determined in a number of systems. Typical results obtained on GaAs: multilayer metallizations are described. Also, degradation of perfection of substrates has been monitored. This work has shown that the stress is not homogeneously distributed and is quite anisotropic. A new high resolution X-ray diffraction technique has been developed for direct observation and study of forward diffracted X-ray beam and anomalous transmission of X-rays through "thin' diamond crystals of varying degrees of perfection.
Electron paramagnetic resonance (EPR) spectroscopy and X-ray diffraction (XRD) studies were carri... more Electron paramagnetic resonance (EPR) spectroscopy and X-ray diffraction (XRD) studies were carried out on synthetic diamonds prepared using nickel, invar and monel as the catalyst solvents at high temperature and high pressure. Nitrogen and nickel were found to be the main impurities present in these specimens. a-Quartz and copper phases were also observed in some cases. The width of EPR hyperfine lines of nitrogen atoms was found to depend on the catalyst solvents used in the synthesis. These studies show that EPR and ...
Six Certified Reference Materials of toxic elements in the concentration range of 1–2 ppm have be... more Six Certified Reference Materials of toxic elements in the concentration range of 1–2 ppm have been prepared in aqueous or HNO3 solution with the participation of fourteen laboratories in India. Various factors affecting the stability of such solutions (hydrolysis, leaching from containers, adsorption, temperature etc.) have been studied and the analytical data for these reference materials have been compiled and
Acta Crystallographica Section A Foundations of Crystallography, 1998
Results of characterization of defects in natural diamond crystals by high-resolution X-ray diffr... more Results of characterization of defects in natural diamond crystals by high-resolution X-ray diffractometry, absolute integrated intensity (p) measurements, topography and diffuse X-ray scattering (DXS) techniques are reported. The samples are (111) natural diamond platelets of dimensions N2 x 2 mm with thickness in the range "-'0.5-1 mm. A five-crystal X-ray diffractometer in three-crystal configuration as well as a four-crystal diffractometer were employed with Mo Keg 1 as the exploring radiation. Infrared absorption measurements showed that the samples belong to type Ia variety and contained varying concentrations of A and B forms of nitrogen aggregates as well as platelets. There were large variations in the values of diffraction curve half-widths (18 to 550") and values ofp (2.4 × 10-5-76 x 10-5 rad) for 111 reflection, showing a wide variation in crystalline perfection. Projection and composite stationary X-ray topographs recorded with different diffraction vectors showed the presence of defects like low-angle boundaries. From the analysis of the observed distribution of diffuse X-ray scattering (DXS), point defect clusters were characterized. The clusters were of interstitial as well as vacancy type. The sizes of the defect clusters (Re1) were determined to be in the range 40 to 190 nm and the volumes of the defect clusters (At1) were in the range ~1 × 10-2s-28 × 10-2s m 3. The defect clusters with sizes reported here could be investigated as the measurements were made close to the reciprocal-lattice points. The platelet size was found to vary inversely with the total concentration of nitrogen.
Acta Crystallographica Section A Foundations of Crystallography, 1987
Point defect aggregates in nearly perfect single crystals produce anisotropic diffuse X-ray scatt... more Point defect aggregates in nearly perfect single crystals produce anisotropic diffuse X-ray scattering (DXS) from reciprocal space around reciprocal lattice points (relps)
Acta Crystallographica Section A: Crystal Physics, Diffraction, Theoretical and General Crystallography, Mar 1, 1980
High-resolution diffuse X-ray scattering (DXS) measurements have been made on dislocation-free si... more High-resolution diffuse X-ray scattering (DXS) measurements have been made on dislocation-free silicon single crystals of the following types:(1) as-grown specimen with no heat treatment (labelled as NHT);(2) specimen heated at 1273 K under oxygen for 10 h [labelled as HT (1)] and (3) specimen heated at 1273 K under oxygen for 50 h [labelled as HT (2)]. Reciprocal space around the 111 reciprocal-lattice point in (1,-1, 1) geometry has been explored using a Cu K exploring beam. From the distribution of DXS intensity it was ...
Secretion of microneme proteins is essential to Plasmodium invasion but the molecular composition... more Secretion of microneme proteins is essential to Plasmodium invasion but the molecular composition of these secretory organelles remains poorly defined. Here, we describe the first Plasmodium microneme proteome. Purification of micronemes by subcellular fractionation from cultured ookinetes was confirmed by enrichment of known micronemal proteins and electron microscopy. Quantitation of electron micrographs showed >14‐fold microneme enrichment compared to the intact ookinete, such that micronemes comprised 85% of the identifiable organelles in the fraction. Gel LC‐MS/MS of the most abundant protein constituents of the fraction identified three known micronemal proteins chitinase, CTRP, SOAP, together with protein disulphide isomerase (PDI) and HSP70. Highly sensitive MudPIT shotgun proteomics described a total of 345 proteins in the fraction. M1 aminopeptidase and PDI, the former a recognised target of drug development, were both shown to have a micronemal location by IFA. We furt...
Rab proteins are pivotal components of the membrane trafficking machinery in all eukaryotes. Dist... more Rab proteins are pivotal components of the membrane trafficking machinery in all eukaryotes. Distinct Rab proteins locate to specific endomembrane compartments and genomic studies suggest that Rab gene diversity correlates with endomembrane system complexity; for example unicellular organisms generally possess 5-20 Rab family members and the size of the repertoire increases to 25-60 in multicellular systems. Here we report 65 open reading frames from the unicellular protozoan Trichomonas vaginalis that encode distinct Rab proteins (TvRabs), indicating a family with complexity that rivals Homo sapiens in number. The detection of gene transcripts for the majority of these genes and conservation of functional motifs strongly suggests that TvRabs retain functionality and likely roles in membrane trafficking. The T. vaginalis Rab family includes orthologues of the conserved subfamilies, Rab1, Rab5, Rab6, Rab7 and Rab11, but the majority of TvRabs are not represented by orthologues in other systems and includes six novel T. vaginalis specific Rab subfamilies (A-F). The extreme size of the T. vaginalis Rab family, the presence of novel subfamilies plus the divergent nature of many TvRab sequences suggest both the presence of a highly complex endomembrane system within Trichomonas and potentially novel Rab functionality. A family of more than 65 Rab genes in a unicellular genome is unexpected, but may be a requirement for progression though an amoeboid life-cycle phase as both Dictyostelium discoideum and Entamoeba histolytica share with T. vaginalis both an amoeboid life cycle stage and very large Rab gene families.
Investigations were made of lattice imperfections in straight cadmium, iron, and copper whiskers ... more Investigations were made of lattice imperfections in straight cadmium, iron, and copper whiskers by analysing the Laue diffraction photographs of the whiskers recorded with a microfocus X-ray source (focal spot ≈ 40 μm in diameter). Perfect whiskers gave single and sharp Laue spots. The other whiskers gave irregular shaped Laue spots, or Laue spots consisting of two fine components (doublets), or streak like Laue spots. None of the investigated perfect cadmium, iron, and copper whiskers was found to contain an axial screw dislocation. However, the lattice planes of these whiskers were found to be deformed in a complicated way. In imperfect whiskers, each set of parallel lattice planes which gave a Laue doublet, in fact consisted of two sets of parallel lattice planes, slightly misoriented with each other. The angle of misorientation was found to be ≈ 10′ for imperfect Cd whiskers. The angular deformation in the lattice planes of some imperfect Cd whiskers was few degrees of are. In perfect whiskers the lattice perfection did not change appreciably on studying different portions of the whiskers. The lattice imperfection in other whiskers decreased on going from the base towards the tip. On annealing, the Laue spots of perfect whiskers did not show appreciable change in the lattice imperfections. Imperfect whiskers, except the ribbons, showed a decrease in the lattice imperfections on annealing. An increase in the lattice and surface imperfections was observed on annealing the ribbons. The present results can be qualitatively explained by assuming that the growth has taken place at the steps provided by an axial screw dislocation or dislocations, which may themselves have annealed out during growth. Gitterfehler in geraden Kamium-, Eisen- und Kupferwhiskern wurden durch Analyse von Laue-Beugungsbildern der Whisker untersucht, die mit einer Mikrofocus-Rontgenstrahlenquelle (Brennpunkt ≈ 40 μm Durchmesser) aufgenommen wurden. Perfekte Whisker ergaben einzelne und scharfe Laue-Punkte. Die anderen Whisker ergaben irregulare Laue-Punkte oder Laue-Punkte, die aus zwei Feinstrukturkomponenten (Dubletts) bestanden, oder streifenformige Laue-Punkte. Es wurde gefunden, das keiner der unter-suchten perfekten Kadmium-, Eisen- und Kupferwhisker axiale Schraubenversetzungen enthielt, das jedoch die Gitterebenen dieser Whisker in komplizierter Weise deformiert waren. In nichtperfekten Whiskern bestand jeder Satz von parallelen Gitterebenen, der ein Laue-Dublett ergab, tatsachlich aus zwei Satzen paralleler, leicht gegeneinander fehlorientierter Gitterebenen. Als Winkel der Fehlorientierung wurde 10′ fur nichtperfekte Cd-Whisker gefunden. Die Winkeldeformation in den Gitterebenen einiger nichtperfekter Cd-Whisker betrug einige Bogengrade. In perfekten Whiskern wurde bei der Untersuchung verschiedener Abschnitte der Whisker keine wesentlichen Anderungen der Gitterbeschaffenheit gefunden. Die Gitterstorungen in den andern Whiskern nahmen von der Basis zur Spitze hin ab. Nach der Temperung zeigten die Laue-Punkte perfekter Whisker keine wesentlichen Anderungen der Gitterstorungen an. Nichtperfekte Whisker, ausgenommen die Streifen, zeigten nach der Temperung einen Ruckgang der Gitterstorungen. Ein Anstieg der Gitter-und Oberflachenstorungen wurde nach Temperung der Streifen beobachtet. Die Ergebnisse konnen qualitativ durch die Annahme erklart werden, das das Wachstum an den Stufen stattgefunden hat, die durch eine axiale Schraubenversetzung oder Versetzungen gebildet wurden und die selbst wahrend des Wachstums ausgeheilt wurden.
We have cloned a single copy gene from the human parasite Trichomonas vaginalis that encodes a pu... more We have cloned a single copy gene from the human parasite Trichomonas vaginalis that encodes a putative protein of 402 amino acids with ∼35% sequence identity to known ␣ subunits of heterotrimeric G-proteins. It contains the characteristic GTP binding domains G-1 to G-5 with the key residues conserved. The new sequence has an unusual N-terminal extension of ∼70 residues that cannot be aligned to reference G-proteins and which is characterised by proline-rich repeats. To investigate the expression and cellular localisation of the protein we produced specific antisera against a recombinant fusion protein. The antisera recognised a protein of an apparent molecular mass of 51 kDa in protein extracts from T. vaginalis and immunofluorescent microscopy established that the protein is localised to discrete endomembranes. Using a protocol designed to purify mammalian heterotrimeric G-proteins incorporating a GTP␥S binding assay, we isolated two proteins from Trichomonas that are recognised by an heterologous GA/1 antisera raised to a peptide of the conserved G-1 domain of G-protein ␣ subunits. These two proteins have an apparent molecular mass of 61 and 48 kDa, respectively, larger and smaller than the translation product of the cloned gene. Consistent with these results, the GA/1 antisera did not cross-react with the fusion protein produced from the gene we have cloned. These data suggest T. vaginalis possesses more than one heterotrimeric G-protein ␣ subunit. Based on the sequence features of the cloned gene and the biochemical properties of the purified proteins, we suggest that these ␣ subunits are likely to be part of classic heterotrimeric G-protein complexes.
Gobind Sagar Reservoir has been created in Himachal Pradesh, India (31° 25´ N and 76 ° 25´E) by d... more Gobind Sagar Reservoir has been created in Himachal Pradesh, India (31° 25´ N and 76 ° 25´E) by damming River Sutlej at village Bhakra in 1963. The average water spread area of this reservoir is 10,000 hectares. Fishermen have organized themselves in the form of co-operative societies. 26 fisheries co-operative societies were working in Gobind Sagar Reservoir up till 2012. June and July months were observed as closed season, no fishing was done during this period. Proper record maintaining of fish catch was done at different levels by the state fisheries department. Different measures like minimum harvestable size, mesh size regulation and prohibition of illegal fishing etc. were taken for fish conservation. Fishermen were actively involved in the management. Gill nets were used for catching fishes from this reservoir. State fisheries department is realizing 15% royalty of the sold fish. Data used in this paper is about the fish catch during 2006-2012 and were obtained from the stat...
High-resolution X-ray diffraction techniques have been employed successfully to evaluate crystall... more High-resolution X-ray diffraction techniques have been employed successfully to evaluate crystalline quality and long-term stability of coiled membranes. The process of fabrication involves photolithography, implantation by 2 MeV N^{2+} ions inn-type GaAs substrates, followed by selective etching. A five-crystal X-ray diffractometer was employed in (+, −, +) setting with an Mo Kα1exploring beam for high-resolution X-ray diffractometry and topography experiments. The exploring-beam width was reduced to illuminate different segments of the coiled membrane. Diffraction curves recorded from the bulk crystal surrounding the sensor had a half width of 26 arcseconds, whereas the half widths from sensor segments were in the range ∼58 to ∼166 arcseconds. Different segments (particularly vertical ones) were identified from the observed angular separations between different diffraction peaks as well as from the shape of the diffraction peaks. It was found that different segments of the sensor ...
High-resolution X-ray diffractometry, absolute integrated intensity (ρ) measurements, diffuse X-r... more High-resolution X-ray diffractometry, absolute integrated intensity (ρ) measurements, diffuse X-ray scattering (DXS) and infrared (IR) absorption techniques were used to investigate the influence of oxygen on the structural perfection of high purity (resistivity of the order of 4 kΩ cm) float zone (FZ) grown (111) silicon single crystals. A multicrystal diffractometer set in (+,-,-,+) geometry, with Mo Kα1radiation, was employed. From the infrared measurements, the oxygen concentration in the sample was determined to be 1.3 × 1017 atoms cm^{-3}. High-resolution X-ray diffraction curves of the as-grown crystal had half-widths of ∼11 arcsec; the ρ value was 3.5 × 10^{-5} rad. To incorporate oxygen in a controlled manner into the specimens, they were annealed under dry oxygen ambient for 8 h in the temperature range 573–1373 K (in eight steps). Up to 723 K there was no appreciable change in oxygen content or in the degree of perfection. Annealing at temperatures (AT) > 873 K resulte...
... Phys., vol. 71, p. 4589, 1992. Discharge Treatment of W-Si System for Silicidation Awatar Sin... more ... Phys., vol. 71, p. 4589, 1992. Discharge Treatment of W-Si System for Silicidation Awatar Singh, PD Vyas, W. S. Khokle, Chatar Singh, and K. La1 ... The re-A. Singh, PD Vyas, and W. S. Khokle are with CEERI, Pilani, Raj. C. Singh is with ITMMEC, ITT Delhi, Delhi, India. ...
READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE. https://nrc-publications.can... more READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE. https://nrc-publications.canada.ca/eng/copyright Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à
Real structure together with composition and elemental purity of single crystals controls their p... more Real structure together with composition and elemental purity of single crystals controls their properties. This paper reviews recent work carried out at the National Physical Laboratory on application of high resolution X-ray diffractometry, topography and diffuse X-ray scattering for direct observation and characterization of real structure of single crystals of silicon, gallium arsenide, diamond and LiNbO 3. A series of six multicrysta! X-ray diffractometers have been designed, developed and fabricated indigenously. The most versatile of these systems is a five crystal X-ray diffractometer with state-of-the-art level resolution. These techniques and equipments have been applied in studying several interesting problems. Even in dislocation-free crystals of silicon, remarkable differences in the defect structure have been observed if the growth method was changed from float zone to Czochralski. Study of effect of externally applied electric fields and ion implantation on real structure of crystals has yielded interesting results. Images of 'filaments' which show nonhomogeneous distribution of electric current through semiconductors and insulators have been recorded for the first time in high resolution traverse topographs. Diffracted X-ray intensities could be modified by externally applied electric fields. It has been shown that implantation of BF~ ions in silicon for producing shallow junctions does not produce homogeneous distribution of boron. The impurity is partially in clustered form. Biaxial stress introduced by thin depositions in substrate crystals are of considerable applied concern. The. value and nature of stress have been determined in a number of systems. Typical results obtained on GaAs: multilayer metallizations are described. Also, degradation of perfection of substrates has been monitored. This work has shown that the stress is not homogeneously distributed and is quite anisotropic. A new high resolution X-ray diffraction technique has been developed for direct observation and study of forward diffracted X-ray beam and anomalous transmission of X-rays through "thin' diamond crystals of varying degrees of perfection.
Electron paramagnetic resonance (EPR) spectroscopy and X-ray diffraction (XRD) studies were carri... more Electron paramagnetic resonance (EPR) spectroscopy and X-ray diffraction (XRD) studies were carried out on synthetic diamonds prepared using nickel, invar and monel as the catalyst solvents at high temperature and high pressure. Nitrogen and nickel were found to be the main impurities present in these specimens. a-Quartz and copper phases were also observed in some cases. The width of EPR hyperfine lines of nitrogen atoms was found to depend on the catalyst solvents used in the synthesis. These studies show that EPR and ...
Six Certified Reference Materials of toxic elements in the concentration range of 1–2 ppm have be... more Six Certified Reference Materials of toxic elements in the concentration range of 1–2 ppm have been prepared in aqueous or HNO3 solution with the participation of fourteen laboratories in India. Various factors affecting the stability of such solutions (hydrolysis, leaching from containers, adsorption, temperature etc.) have been studied and the analytical data for these reference materials have been compiled and
Acta Crystallographica Section A Foundations of Crystallography, 1998
Results of characterization of defects in natural diamond crystals by high-resolution X-ray diffr... more Results of characterization of defects in natural diamond crystals by high-resolution X-ray diffractometry, absolute integrated intensity (p) measurements, topography and diffuse X-ray scattering (DXS) techniques are reported. The samples are (111) natural diamond platelets of dimensions N2 x 2 mm with thickness in the range "-'0.5-1 mm. A five-crystal X-ray diffractometer in three-crystal configuration as well as a four-crystal diffractometer were employed with Mo Keg 1 as the exploring radiation. Infrared absorption measurements showed that the samples belong to type Ia variety and contained varying concentrations of A and B forms of nitrogen aggregates as well as platelets. There were large variations in the values of diffraction curve half-widths (18 to 550") and values ofp (2.4 × 10-5-76 x 10-5 rad) for 111 reflection, showing a wide variation in crystalline perfection. Projection and composite stationary X-ray topographs recorded with different diffraction vectors showed the presence of defects like low-angle boundaries. From the analysis of the observed distribution of diffuse X-ray scattering (DXS), point defect clusters were characterized. The clusters were of interstitial as well as vacancy type. The sizes of the defect clusters (Re1) were determined to be in the range 40 to 190 nm and the volumes of the defect clusters (At1) were in the range ~1 × 10-2s-28 × 10-2s m 3. The defect clusters with sizes reported here could be investigated as the measurements were made close to the reciprocal-lattice points. The platelet size was found to vary inversely with the total concentration of nitrogen.
Acta Crystallographica Section A Foundations of Crystallography, 1987
Point defect aggregates in nearly perfect single crystals produce anisotropic diffuse X-ray scatt... more Point defect aggregates in nearly perfect single crystals produce anisotropic diffuse X-ray scattering (DXS) from reciprocal space around reciprocal lattice points (relps)
Acta Crystallographica Section A: Crystal Physics, Diffraction, Theoretical and General Crystallography, Mar 1, 1980
High-resolution diffuse X-ray scattering (DXS) measurements have been made on dislocation-free si... more High-resolution diffuse X-ray scattering (DXS) measurements have been made on dislocation-free silicon single crystals of the following types:(1) as-grown specimen with no heat treatment (labelled as NHT);(2) specimen heated at 1273 K under oxygen for 10 h [labelled as HT (1)] and (3) specimen heated at 1273 K under oxygen for 50 h [labelled as HT (2)]. Reciprocal space around the 111 reciprocal-lattice point in (1,-1, 1) geometry has been explored using a Cu K exploring beam. From the distribution of DXS intensity it was ...
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Papers by Krishan Lal