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  • 1
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    Massive gene acquisitions in Mycobacterium indicus pranii provide a perspective on mycobacterial evolution (2012)
    Oxford University Press
    Details
    Publication Date: 2012-11-25
    Description: Understanding the evolutionary and genomic mechanisms responsible for turning the soil-derived saprophytic mycobacteria into lethal intracellular pathogens is a critical step towards the development of strategies for the control of mycobacterial diseases. In this context, Mycobacterium indicus pranii (MIP) is of specific interest because of its unique immunological and evolutionary significance. Evolutionarily, it is the progenitor of opportunistic pathogens belonging to M. avium complex and is endowed with features that place it between saprophytic and pathogenic species. Herein, we have sequenced the complete MIP genome to understand its unique life style, basis of immunomodulation and habitat diversification in mycobacteria. As a case of massive gene acquisitions, 50.5% of MIP open reading frames (ORFs) are laterally acquired. We show, for the first time for Mycobacterium , that MIP genome has mosaic architecture. These gene acquisitions have led to the enrichment of selected gene families critical to MIP physiology. Comparative genomic analysis indicates a higher antigenic potential of MIP imparting it a unique ability for immunomodulation. Besides, it also suggests an important role of genomic fluidity in habitat diversification within mycobacteria and provides a unique view of evolutionary divergence and putative bottlenecks that might have eventually led to intracellular survival and pathogenic attributes in mycobacteria.
    Print ISSN: 0305-1048
    Electronic ISSN: 1362-4962
    Topics: Biology
    Published by Oxford University Press
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  • 2
    Electronic Resource
    Electronic Resource
    The influence of an epitaxial CoSi2 layer on diffusion of B and Sb in underlying Si during oxidation (1999)
    Springer
    Fresenius' journal of analytical chemistry 365 (1999), S. 282-285 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The effect of an epitaxial 20 nm thick CoSi2 layer on the diffusion of B and Sb in Si is investigated during oxidation and is compared to thermal diffusion in Si. B and Sb doping superlattices (DSLs) were grown by molecular beam epitaxy (MBE). They consisted of six spikes with peak concentrations of about 1018 cm–3 (B) and about 1019 cm–3 (Sb) and peak centres spaced 100 nm apart. The shallowest spike was capped with 100 nm of Si followed by 20 nm of CoSi2 grown by molecular beam allotaxy (MBA). Oxidation in dry O2 and annealing in pure N2 were performed at temperatures of 800 °C to 1200 °C. Concentration depth profiles were measured by secondary ion mass spectrometry (SIMS). The results showed that the diffusion of B and Sb in Si was markedly different for specimens with or without a CoSi2 layer. Oxidation enhanced diffusion (OED) of B and oxidation retarded diffusion (ORD) of Sb was observed for specimens without a CoSi2 layer. The effect of CoSi2 layer was a strong retardation of B diffusion and an enhancement of Sb diffusion. The B diffusivity was retarded by a factor of 2–10 as compared to the thermal diffusivity and by a factor of 20–100 as compared to the corresponding diffusivity for oxidation of Si without a CoSi2 layer. Sb diffusivity was enhanced by a factor of 2 with respect to thermal diffusivity and by about a factor of 5 as compared to the case without a CoSi2 layer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160051489
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  • 3
    Electronic Resource
    Electronic Resource
    Crystalline to amorphous transition and band structure evolution in ion-damaged silicon studied by spectroscopic ellipsometry (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 659-669 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Crystalline to amorphous transition and subsequent microstructural evolution in silicon induced by Ar+-ion implantation over a wide range of ion fluences (6×1013–1×1017 cm−2) have been investigated by spectroscopic ellipsometry. In the evaluation of the optical and microstructural properties of the damaged layer, the contribution of the surface overlayer to the measured dielectric spectra was separated by fitting a multilayer model with an effective medium approximation. The best fit to the dielectric spectra for disordered silicon could be obtained by taking our highest-fluence implanted (fluence=1×1017 ions/cm2) amorphous silicon (a-Si) data as reference data instead of a-Si data available in the handbook. The derivative spectra as a function of fluence show a distinct and sharp transition from the crystalline to amorphous phase. The threshold fluence for this transition is derived from fitting. Evaluation of standard sum rules and optical moments for imaginary part of the pseudodielectric function reveals no substantial change in various physical parameters below the transition indicating their insensitivity to point defects, while it shows a large change with fluence above the threshold for amorphization. The disorder induced changes in the effective dielectric constant, number of valence electrons per atom participating in optical transition, Penn gap energy, average bond length, coordination number, effective dispersion oscillator energy, an average strength of the interband optical transition with fluence is discussed on the basis of microstructural evolution and corresponding band structure modification. It is also shown that the dielectric functions of damaged silicon are well represented by a sum of six classical Lorentz oscillators. With increasing fluences, each of the oscillator amplitude decreases and linewidth increases except for the 3.3 eV transition which shows increasing amplitude with fluence. These results are discussed in the context of short-range order/disorder and effective band gap reduction along with flattening of the bands with increasing fluence above the amorphization threshold. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1379055
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  • 4
    Electronic Resource
    Electronic Resource
    Inclusion Complex of .gamma.-Cyclodextrin-C60: Formation, Characterization, and Photophysical Properties in Aqueous Solutions (1994)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 98 (1994), S. 4756-4759 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100068a044
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of an epitaxial CoSi2 layer on diffusion of B and Sb in Si during annealing and oxidation (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 7639-7645 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The diffusion of B and Sb in Si, with and without a 20-nm-thick epitaxial CoSi2 layer on top, is investigated, during annealing and oxidation, using doping superlattices (DSLs). CoSi2 layers were grown on Si by molecular beam allotaxy. DSLs were grown by molecular beam epitaxy. They consisted of six spikes with peak concentrations of 1018 cm−3(B) and about 1019 cm−3(Sb) with peak centers spaced 100 nm apart. The shallowest spike was capped with 100 nm of Si followed by 20 nm of CoSi2. Annealing in pure N2 and oxidation in pure O2 were performed at temperatures ranging from 800 to 1200 °C. Concentration depth profiles were measured by secondary ion mass spectrometry. The results showed that the dopant diffusion in Si was markedly different with or without a CoSi2 layer. For specimens without CoSi2 layer, we observed oxidation enhanced diffusion of B and oxidation retarded diffusion of Sb in accordance with the literature. However, the effect of CoSi2 layer was a strong retardation of B diffusion and an enhancement of Sb diffusion. The B diffusivity was retarded by a factor of 2–10 as compared to the thermal diffusivity and by a factor of 20–100 as compared to the corresponding diffusivity for oxidation of Si without a CoSi2 layer. Sb diffusivity was enhanced by a factor of 2 with respect to thermal diffusivity and by about a factor of 5 as compared to the case without a CoSi2 layer. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.370566
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  • 6
    Electronic Resource
    Electronic Resource
    High frequency regeneration of plantlets from the leaf-bases via somatic embryogenesis and comparison of polypeptide profiles from morphogenic and non-morphogenic calli in wheat (Triticum aestivum) (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 82 (1991), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: High frequency regeneration via somatic embryogenesis was achieved in the leaf-base cultures of wheat (Triticum aestivum L. cv Sonalika) by optimizing the concentration of the hormone, 2,4-dichlorophenoxy acetic acid, and selecting for the appropriate part of the leaf base as explant. It was possible to distinguish compact (morphogenic) and friable (non-morphogenic) calli by the naked eye, after about 60 days of culture on medium enriched with 2,4-dichlorophenoxy acetic acid. The fact that the compact calli are morphogenic, while the friable ones are not, was evident from the observation that only the former formed plantlets after transfer to the basal medium. The morphogenic and non-morphogenic cultures showed substantial difference in soluble protein content on a fresh weight basis. A comparison of silver-stained profiles of soluble polypeptides from morphogenic and non-morphogenic calli revealed many polypeptides specifically associated with either type of calli.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1991.tb02955.x
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  • 7
    Electronic Resource
    Electronic Resource
    Transient expression of electroporated gene in leaf protoplasts of indica rice and influence of template topology and vector sequences (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 89 (1993), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Electroporation was used for gene delivery and evaluation of various parameters affecting transient expression of a gene for β-glucuronidase (gus) in leaf protoplasts of Oryza sativa var. Basmati-370. Transient expression was found to be dependent on voltage, capacitance, amount of plasmid and carrier DNA as well as period of culture. Maximum GUS activity was obtained when a 150 ms pulse at 300 V cm-1 and 200 μF was applied to the protoplasts (l–2×106ml−1) in an electroporation buffer containing 20 μg of plasmid and 30 μg of calf thymus DNA, assayed 48 h after electroporation. DNA topology did not influence expression of the gene as both linear and supercoiled templates resulted in similar activities, but a 4-fold decrease in expression was observed if the gene was excised, reflecting the positive influence of vector sequences on gene expression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1993.tb05294.x
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  • 8
    Electronic Resource
    Electronic Resource
    The Formation of Protective Alumina-Based Scales During High-Temperature Air Oxidation of γ -TiAl Alloys (2000)
    Springer
    Oxidation of metals 54 (2000), S. 211-235 
    Details
    ISSN: 1573-4889
    Keywords: intermetallics ; titanium aluminides ; Z-phase ; silver additions ; alumina scale
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The effect of Ag additions on the oxidation behavior of γ-TiAl hasbeen studied. The materials investigated containing 47–50 at.% Aland 0–5 at.% Ag were tested with respect to oxidation resistanceduring exposure in air at 800°C. The exposures up to around 1600 hrshowed that suitable Ag additions can promote formation of long-term,protective, alumina scales on γ-TiAl alloys. Extensive analysesof the oxidation products using optical metallography SEM, XRD, EPMA,and SIMS revealed that Ag stabilizes the Z-phase (Ti5Al3O2) in thesubscale-depletion layer thereby preventing formation of α2-Ti3Alas well as Ti-rich nitrides, which are responsible for the destructionof alumina scales in common γ -TiAl alloys. The best results wereobtained for the alloy Ti–50Al–2Ag; even during exposures aslong as around 1600 hr, this alloy still appeared to form a stable aluminalayer. It was found that high Ag additions of 5% were detrimental afterlonger exposure times due to extensive Ag precipitationat the interface between the alloy and depletion layer, resulting inlocalized formation of rapidly growing, mixed-oxide scales.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004694111032
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  • 9
    Electronic Resource
    Electronic Resource
    Amelioration of acute mountain sickness: Comparative study of acetazolamide and spironolactone (1986)
    Springer
    International journal of biometeorology 30 (1986), S. 293-300 
    Details
    ISSN: 1432-1254
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Abstract Acetazolamide and spironolactone were evaluated for their ameliorating effects on acute mountain sickness (AMS). Studies were conducted in 29 healthy male subjects in lowland and at a height of 3,500 m after their airlift. A modified General High Altitude Questionnaire (GHAQ) was used to evaluate the effectiveness of these drugs for reducing the intensity of AMS symptoms. Both the drugs were found to be helpful in minimising the occurrence as well as severity of most of the symptoms. Spironolactone seems to be a superior prophylactic agent than acetazolamide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02189364
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  • 10
    Electronic Resource
    Electronic Resource
    Body fluid status on induction, reinduction and prolonged stay at high altitude of human volunteers (1990)
    Springer
    International journal of biometeorology 34 (1990), S. 93-97 
    Details
    ISSN: 1432-1254
    Keywords: Body fluid ; High altitude, illness ; Human adaptation ; Blood gas ; Plasma volume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Abstract Studies on adaptation to high altitude (HA) of 3500 m in the Himalayas were conducted in three phases, each including 10 normal and healthy males normally resident at sea-level. Phase I subjects had no previous experience of HA, phase II subjects after 4–6 months at HA were airlifted to sea-level and phase III subjects stayed continuously for 6 months at 3500 m. Body fluid compartments and blood gases were determined in all three groups. Plasma volume was highly elevated in the phase II subjects on reinduction to sea-level from HA. In comparison to phase I subjects, the retention of fluid in extracellular compartment was increased at HA leading to increased susceptibility to high altitude illness. Phase III subjects were hyperhydrated with decreased plasma volume and increased PO2 in comparison to the other two groups.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01093454
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