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  • 1
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A chromosomal survey using standard lymphocyte cultures employing different media and G-banding techniques was initiated in 1984. This study became particularly important following the tragic gaseous exposure of the population in Bhopal at midnight on 2 December 1984. We have been able to formulate a chromosomal profile for each person whom we have studied; during 1986–1988, 154 persons were examined twice. Among seemingly normal individuals, as many as 20% might possess some chromosomal abnormality; of these, 50% may develop, at a later date, some kind of pathological complication (such as tumours, recurrent abortion or transmission of defects to their offspring). The people exposed to methyl isocyanate have repeatedly shown Robertsonian translocations, mostly in acrocentric chromosomes 13 and 21. Other types of translocations have been studied among all exposed (53) and normal (101) persons; the involvement of chromosomes 5, 9, 11, 14 and 16 is statistically significant (P= 〈0.001). One of the major clinical symptoms is dyspnoea; we have estimated that almost all seriously dyspnoeic patients have developed at least two categories of chromosomal aberrations, one of which is Robertsonian translocation, in at least 10% metaphases. Our chromosomal survey will be of significance because we are able to identify people with chromosomal aberrations that might be correlated with future pathological consequences of the accident. The “chromosomal load” that can be sustained with an apparently normal phenotype can also be measured.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 225-229 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Characteristics of a liquid crystal system, comprised of a shear sensitive cholesteric monomer liquid crystal thin-film coated on a liquid crystal polymer substrate, are described. The system provides stable Grandjean texture, a desirable feature for shear stress measurements using selective reflection from the monomer liquid crystal helix structure. Impingement of gas or air flow on the monomer liquid crystal free surface changes the wavelength of the selective reflection for an incident white light from red towards blue with increase in the rate of gas flow. The contrast of the selectively reflected light improves considerably by providing a thin (∼5 μm) black coating at the monomer-polymer interface. The coating thickness is such that the steric interactions are still sufficiently strong to maintain Grandjean texture. For a small angle of incidence (∼15°) of a monochromatic light, the measurement of the reflected light intensity normal to the monomer-polymer liquid crystal interface enables us to determine the wavelength (λs) for selective reflection as a function of the gas flow differential pressure (Δp) applied in the plane of the interface. In the range of the Δp (0–100 mmHg) used in the present studies, the variation of λs with Δp is linear with a slope ∼2 nm/mmHg. Furthermore, the shear stress effects are reversible unlike for monomer liquid crystal−metal systems used so far for flow visualization on wind-tunnel model surfaces. Thus the present system offers a suitable method for direct on-line measurement of shear stress field from measurement of λs for an incident white light.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 1954-1956 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Utilizing a simple new configuration, one rigid surface and the other exposed directly to the gas flow, elasto-optic switching in thin (∼2 μm) ferroelectric liquid crystal films is observed when a gas flow is impingement in the plane of smectic layers. The elasto-optic response caused by the shear stress is large, fast, and reversible.
    Type of Medium: Electronic Resource
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  • 4
    Publication Date: 2011-08-24
    Description: Characteristics of a liquid crystal system, comprised of a shear-sensitive cholesteric-monomer liquid crystal thin-film coated on a liquid-crystal polymer substrate, are described. The system provides stable Grandjean texture, a desirable feature for shear-stress measurements using selective reflection from the monomer liquid-crystal helix structure. Impingement of gas or air flow on the monomer liquid-crystal free surface changes the wavelength of the selective reflection for an incident white light from red toward blue with increase in the rate of gas flow. The contrast of the selectively reflected light improves considerably by providing a thin black coating of about 5 microns at the monomer-polymer interface. The coating thickness is such that the steric interactions are still sufficiently strong to maintain Grandjean texture. For a small angle of incidence of a monochromatic light, the measurement of the reflected light intensity normal to the monomer-polymer liquid-crystal interface enables the determination of the wavelength for selective reflection as a function of the gas-flow differential pressure applied in the plane of the interface. The variation of the wavelength with the pressure is linear with a slope of about 2 nm/mmHg. Furthermore, the shear-stress effects are reversible unlike for monomer liquid crystal-metal systems used for flow visualization on wind-tunnel model surfaces. The present system offers a suitable method for direct on-line measurement of shear stress field from measurements of the wavelength for selective reflection for an incident white light.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments (ISSN 0034-6748); 63; 225-229
    Format: text
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 62 (1991), S. 474-479 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new sensor for optical detection of shear stress field induced by air or gas flow on a rigid surface is reported. The sensor uses the novel effects of shear induced optical switching in ferroelectric liquid crystals. The principle of operation of the sensor is described and a theoretical model for the optical response to shear stress is given. Director dynamics and system-free energy considerations predict a system response time ≈10 ns for an applied shear stress step of ≈700 Torr. A thin (≈1 μm) ferroelectric liquid crystal film coated on a flat glass model surface is exposed to gas flow from a micro wind tunnel attached to the polarizing microscope employed for optical measurements. Schlieren texture of the thin film consists of two stable domains separated by a domain wall. Gas or air flow on the liquid crystal surface induces director reorientation resulting in optical contrast. Transmitted and reflected light intensities from polarization microscopy provide measurement of the flow parameters. System response time τ∼150 μs has been estimated from the material viscosity and the time variation of the applied shear stress in the experiment. Optical response is linear for applied differential pressures up to ≈800 Torr beyond which it tends to saturate. Second-order nonlinear effects are observed for flow rates beyond ≈42 l/min. The configuration used in the present method overcomes many of the limitations of similar measuring techniques including those using cholesteric liquid crystals. The present method offers a preferred alternative for flow visualization and skin friction measurements in wind-tunnel experiments on laminar boundary layer transition investigations.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 21-23 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ferroelectric liquid crystals in a new configuration, termed partially exposed polymer dispersed ferroelectric liquid crystal (PEPDFLC), respond to external pressures and demonstrate pressure-induced electro-optic switching response. When the PEPDFLC thin film is sandwiched between two transparent conducting electrodes, one a glass plate and the other a flexible sheet such as polyvenylidene fluoride, the switching characteristics of the thin film are a function of the pressure applied to the flexible transparent electrode and the bias voltage across the electrodes. Response time measurements reveal a linear dependence of the change in electric field with external pressure.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1475-2743
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract. A field experiment was conducted over two years in one of the mountain Alfisols of the Western Himalayas to study the effects of phosphorus and mulching on phosphorus use efficiency (PUE) and productivity of wheat (cv. S-308) at difference growth stages. The source of phosphorus was single superphosphate at 0, 26, 52 and 78 kg P/ha whereas the sources of mulching materials were pine needles (Pinus longifolia), lantana weed (Lantana camara) at 8 t/ha and transparent polyethylene sheet compared with no mulch.The phosphorus use efficiency (PUE) at tillering, flowering and harvesting was greatest at the lowest dose of P and decreased as the P levels were increased. However, the increased levels of P up to 78 kg/ha, significantly improved the dry matter yield at tillering stage (30%) and flowering stage (93%) and also the grain yield (139%) and straw yield (148%) at the harvest stage. The application of mulching materials in general, and polyethylene in particular, significantly increased the phosphorus use efficiency and the productivity of wheat by 27% at tillering stage; 17% at flowering stage, and by 98 and 110% in the case of grain and straw yield at harvest stage.Although the polyethylene mulch effect was physically superior to the other materials, the latter gave greater financial returns. Consequently, the economic optimum application of P in association with 8 t/ha of lantana mulch was found to be 53 kg/ha over two years, whereas, in the absence of mulching, it was 58 kg/ha.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 538-541 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Partially exposed polymer dispersed liquid crystal thin film (10–25 μm) deposited on a flat glass substrate has been used for the first time to measure skin friction. Utilizing the shear stress induced director reorientation in the partially exposed liquid crystal droplets, optical transmission under crossed polarization has been measured as a function of the air flow differential pressure. Direct measurement of the skin friction with a skin friction drag balance, under the same aerodynamic conditions, lets us correlate the skin friction with optical transmission. This provides a unique technique for the direct measurement of skin friction from the transmitted light intensity. The results are in excellent agreement with the model suggested in this paper.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A description of the design and setup of an experimental technique for measurement of the response function in shear sensitive liquid crystals has been reported. Utilizing the selective reflection characteristics of cholesteric liquid crystals, the method is capable of measuring the delay, rise, and relaxation times in response to a given dynamic shear stress as a function of the wavelength of the incident light. Application of a step input shear stress results in a liquid crystal time response that can be described as consisting of an initial delay, a shear induced helix deformation, and a relaxation to the initial state through diffusion processes. The method has been used for quantitative calibration of a shear sensitive liquid crystal by observing the peak in reflected light intensity, at a given wavelength, as a function of the shear stress. The selective reflection wavelength (λs) decreases linearly with an increase in shear stress (σ) and has a slope dλs/dσ≈10 nm/psi. The results suggest that in order to obtain quantitative information on the flow parameters over a test surface, three reflection spectra are required: one from a white surface and the other two from the liquid crystal surface one before and one in the presence of shear stress respectively. Free energy calculations for the elastic deformation of the liquid crystal suggest a time response of the liquid crystal for a step input in shear stress. Transport of the broken helix swarms has been suggested as a means for the helix relaxation to zero shear state even in presence of shear.
    Type of Medium: Electronic Resource
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  • 10
    Publication Date: 2004-12-03
    Description: Electrorheological fluids (ERF) are an intriguing class of non-Newtonian industrial fluids. They consist of fine dielectric particles suspended in liquids of low dielectric constants. The objectives of this research were to select a particulate system such that: (1) its density can be varied to match that of the selected liquid, and (2) the dielectric constant of the particles and the liquids should be such that the critical fields needed for asymptotic increase in viscosity are less than or equal to 10 KV/cm. Synthetic Zeolite particles were selected as the solute/suspensions. Octoil oil was selected as the solvent. The results are summarized here.
    Keywords: Nonmetallic Materials
    Type: Proceedings of the 4th Annual Workshop: Advances in Smart Materials for Aerospace Applications; 187-190; NASA-CP-10185
    Format: text
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