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  • 2000-2004  (3)
  • 1990-1994  (7)
  • 1
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 512-514 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The third-order optical nonlinearity χ(3) of two novel guest-host polymers has been measured. The polymers consisted of nickel dithiolene guest molecules in a polymethylmethacrylate host and were prepared as cast or spun films. The optical nonlinearity was measured by degenerate four-wave-mixing experiments at a wavelength of 1.06 μm using 100-ps laser pulses. χ(3) coefficients of up to 10−17 m2/V2 were observed, corresponding to nonlinear refractive index n2 of up to 10−8 cm2/kW with a damage threshold (approximately-greater-than)1 GW/cm2.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 107-109 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The third-order optical nonlinearity χ(3), linear absorption coefficient α, and the two-photon absorption coefficient β of two nickel dithiolene complexes are reported. The nonlinearities were measured at 1064 nm using 100 ps pulses. Molecular nonlinearities 103 times those of carbon disulphide were observed. Two figures of merit were calculated from the data Δnsat/αλ=5 and n2/2βλ(approximately-greater-than)2, where α and β are the linear and two-photon absorption coefficients and n2 the nonlinear refractive index. These figures are compatible with those required for simple all-optical switching devices.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    British journal of dermatology 150 (2004), S. 0 
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background  Optical coherence tomography (OCT) is a noninvasive morphological method for investigating human skin. It allows high-resolution in vivo imaging of inflammatory skin diseases and tumours. Because it is a newly developed method, systematic studies on standardization and on evaluation of factors influencing the representation of the skin have not yet been performed.Objectives  In this study, normal human skin was treated with various external stimuli which induce changes of function and morphology. Changes in stratum corneum thickness as well as changes induced by pigmentation, oedema and erythema were investigated using OCT.Methods  Healthy skin of human volunteers was treated with tape stripping, ultraviolet A irradiation, water, histamine, nicotinic acid and various ointments.Results  In the tape stripping experiment, the thickness of the horny layer was quantified and monitored. Pigmentation increased the light attenuation of the tissue, whereas hydration and erythema led to a slight decrease of scattering. Topical treatment of the skin gave a nonspecific increase of penetration depth of the light due to the lower reflectivity of the surface.Conclusions  There are various physiological conditions which influence optical properties of the skin. These parameters should be considered when performing standardized OCT studies.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Two-dimensional gel electrophoresis was used to follow low changes in gene expression associated with antibiotic (bialaphos) biosynthesis in Streptomyces hygroscopicus. Cultures were pulse-labelled with [35S]-methionine before, during, and after the switch from primary to secondary metabolism in order to compare kinetic profiles of bialaphos (antibiotic) production (bap) genes during this metabolic transition. Separation of gene products on two-dimensional gels revealed that 27 were dependent on brpA for optimal expression and were activated as the culture approached stationary phase. Genes which encoded 10 brp4-dependent proteins were mapped to a 10 kb Sstl fragment of the 35 kb bap gene cluster by expressing them in Streptomyces lividans using the thiostrepton-inducible tipA promoter. N-terminal amino acid sequences of two brpA-dependent proteins, obtained by direct microsequencing of protein spots excised from two-dimensional gels, identified them as gene products mapping to the same region and involved in secondary metabolic conversions of the bap pathway. The kinetics of synthesis of 16 brpA-dependent gene products were characterized using QUEST computer software. Cluster analysis performed on the kinetics of synthesis of 346 of the most highly expressed gene products of HP5-29, including 16 brpA-dependent ones, identified 75 families having distinct patterns of expression. Many brpA-dependent proteins were clustered together; 10 were found in one kinetic family. These kinetic families also included brpA-independent gene products perhaps subject to similar regulatory mechanisms and thus possibly involved in bialaphos biosynthesis. The activation/derepression of bap expression took place as cultures approached stationary phase and was temporally related to synthesis of ppGpp.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 46 (1990), S. 1231-1233 
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Optical and quantum electronics 22 (1990), S. 297-318 
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Organic second-order nonlinear materials are currently receiving considerable attention for fabrication of frequency mixing and electro-optic devices. In this paper the key concepts in the development of organic nonlinear materials and waveguide device design are introduced. The recent advances in nonlinear waveguides for frequency doubling and electro-optic devices are reviewed.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    BT technology journal 18 (2000), S. 73-75 
    ISSN: 1573-1995
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The traditional 'Von Neumann' computing architecture is serial and digital. This way of organising things has proved to be very powerful and has allowed spectacular progress in computation, riding on the back of spectacular increases in speed of the central processor. Though the Von Neumann model has outstripped futurologists' dreams in its favoured domains, it has failed to meet expectations in others. Highly parallel, asynchronous, distributed problems highlight its weaknesses. Such complexity is inevitable in today's highly connected networks and dynamic environments with information asymmetries and delays, and myriad interactions among components. There are two ways to address the shortcomings in difficult but important problem domains like these. One is to increase the speed of traditional computing. This is being done, with year-on-year increases in hardware and software performance. The second is to seek new computational architectures which address problems more efficiently. This is also an active research area, and it is the subject of this paper. We are drawing inspirations from nature to deal with the twin challenges of parallel asynchronous problem domains and network system complexity that characterise the information age.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-2665
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1573-5176
    Keywords: cadmium adsorption ; Ectocarpus siliculosus ; growth conditions ; adsorption parameters ; regeneration ; electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Non-living, freeze-dried material of the brown algaEctocarpus siliculosus (Phaeophyceae) demonstrated high equilibrium uptake of Cd from aqueous solutions (Fehrmann & Pohl, 1993). The alga was grown in 250-L photobioreactors under various growth conditions (light, salinity and nutrient concentrations) in order to obtain larger quantities of biomass and to improve its Cd adsorption capacity. To derive further knowledge on the biosorbant phenomenon different adsorption parameters such as pH for the sorption process and kinetics of Cd adsorption were tested. The maximum adsorption capacity of the freeze-dried biomass exceeded 41 mg Cd per g biomass. After repeated addition of low Cd concentrations the maximum adsorption capacity was lower (31.4 mg Cd per g biomass). In comparison with other adsorbing materials (activated carbon, silica gel, siliceous earth)E. siliculosus showed significantly higher adsorption capacity. Desorption of deposited Cd with 0.1 M HCl resulted in no changes of the adsorption capacity through five subsequent adsorption-/desorption-cycles. Hence, driedE. siliculosus appears to be an efficient material for the elimination of Cd from industrial waste water. Transmission electron microscopic investigations showed an electron dense area in the outer surface layers of the cell wall after Cd adsorption indicating the most likely location of Cd fixation.
    Type of Medium: Electronic Resource
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