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  • 1
    Electronic Resource
    Electronic Resource
    Effects of co-dopant concentrations and excitation conditions on the 2 μm fluorescence dynamics in Tm, Ho:YLF crystals (1994)
    Springer
    Applied physics 59 (1994), S. 253-258 
    Details
    ISSN: 1432-0630
    Keywords: 42.70
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Results of spectroscopic studies carried out on Tm, Ho:YLF crystals are reported. In particular, we have investigated the effects of the co-dopant concentrations on the time evolution of the fluorescence at 2 μm emitted in response to short-pulse laser excitation at 792 nm. The fluorescence intensity profiles are analyzed in terms of their temporal and amplitude characteristics over a wide range of excitation conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00348228
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  • 2
    Electronic Resource
    Electronic Resource
    Thermodynamics of isothermal vitrification by chemical reactions in a liquid (1992)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 14 (1992), S. 763-766 
    Details
    ISSN: 0392-6737
    Keywords: Glass transitions ; Calorimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary We report here first observations of the decrease in heat capacity during isothermal vitrification of a thermosetting polymer. A new experimental method has been developed for this study which allows simultaneous measurements of both the heat capacity and the enthalpy released as chemical reactions occur in quasi-isothermal conditions. During the curing the heat capacity of a thermoset first increases slightly, undergoes an abrupt decrease in a narrow range of time and thereafter slowly decreases. The abrupt decrease represents the irreversible transition of the liquid to a vitreous solid which is equivalent to the reversible glass transition appearing in a supercooled liquid when the temperature is lowered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02451722
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  • 3
    Electronic Resource
    Electronic Resource
    Simultaneous dielectric spectroscopy and calorimetry of the dynamics during a macromolecules growth (1996)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 18 (1996), S. 1443-1448 
    Details
    ISSN: 0392-6737
    Keywords: Glass transitions ; Calorimetry ; Dielectric loss and relaxation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary A method and an instrument has been developed for measuring almost simultaneously and continuously in time three different quantities: i) the heat evolved during the course of exothermic reactions, ii) the heat capacity and iii) the dielectric spectra of a liquid or solid sample. By using this instrument, we have studied the decrease in the d.c. conductivity and the increase in the relaxation time as molecules in an isothermally kept liquid chemically react to produce, irreversibly, a macromolecular structure until the liquid vitrifies and becomes rigid. The number of covalent bonds formed in the structure,n, has been calculated and the dielectric relaxation time, τ, is related ton. This τ increases progressively more rapidly withn, and decreases, of course, on increasing the temperature. A compensation between these two effects determines the dynamic behaviour observed during rate heating. The effect of temperature is found to predominate. Such observations have been made possible by means of the new instrument.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02453785
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  • 4
    Electronic Resource
    Electronic Resource
    A calorimeter for the electrolytic cell and other open systems (1996)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 18 (1996), S. 1333-1346 
    Details
    ISSN: 0392-6737
    Keywords: Energy-conversion spectro-analytical methods (e.g., photoacoustic, photothermal, and optogalvanic spectroscopic methods) ; Calorimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary We present here a calorimetric method and the construction details of a differential calorimeter useful for studying the reactions in an electrolytic cell and more generally slow chemico-physical processes occurring in thermodynamically open systems. The method allows measurements of the heat balance of the cell, from which the enthalpy change of the process under investigation can be calculated. The theoretical description of the calorimetric cell and the results of several studies planned to describe the performances of the instrument up to the boiling point of the electrolytic solution are reported. The features of this calorimeter fulfil most of the requirements of ≪col fusion≫ experiments, where the heat production is the fundamental and controversial aspect. By controlling both the heat and the matter exchanged, the calorimeter can be utilised also to study bioenergetic processes,e.g. fermentation, microbial metabolism and biodegradation, and liquid phase chemical reactions, involving gases as reactants and/or products.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02453267
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  • 5
    Electronic Resource
    Electronic Resource
    Time-dependent heat capacity of water-lysozyme solution (1992)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 14 (1992), S. 199-205 
    Details
    ISSN: 0392-6737
    Keywords: Heat capacities of liquids ; Biomechanics, biorheology, biological fluid dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary We report here the first observation of the time-dependent heat capacity of water-lysozyme solution. The observed increase of heat capacity in time occurs independently of the lysozyme concentration and thepH value of the solvent. The time necessary to attain the heat capacity equilibrium value and the amplitude of the effect are not well reproducible; the former tends to increase with temperature, while the amplitude decreases and practically disappears about 35°C. Evolution of a spatial order of the proteins in water and/or of water molecules interacting with the proteins is considered as a possible explanation for the results. The phenomenon promises to be an important tool to study the role of water in biological organization and activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02457352
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  • 6
    Electronic Resource
    Electronic Resource
    Screening effect of impurities in metals: a possible explanation of the process of cold nuclear fusion (1989)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 11 (1989), S. 927-932 
    Details
    ISSN: 0392-6737
    Keywords: Fluids, plasmas and electric discharges ; Fermi-Thomas model ; Fusion reactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary The screening length of the deuterium ion by surrounding electrons in a palladium metal lattice, as estimated using two approaches—viz. the Thomas-Fermi screening theory and the Debye screening theory for plasmas in metal—is found to be less than the interatomic separation of ordinary hydrogen molecules. This has important implications for the possibility of cold nuclear fusion at room temperature, since slight fluctuations in equilibrium conditions may drive the deuterons to fuse together. The relative magnitudes of screening length for the cold nuclear fusion regime and classical hot nuclear regimes (inertial and magnetic confinement) reveal that in the former a comparatively smaller amount of energy is needed to overcome the repulsive Coulomb barrier between two deuterium ions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02455300
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  • 7
    Electronic Resource
    Electronic Resource
    Simple, compact, high-repetition rate XeCl laser (1985)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 56 (1985), S. 674-676 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Operation of a compact, corona-preionized, XeCl excimer laser producing average output power in excess of 1 W at pulse repetition frequencies of up to 750 Hz is reported. This device is simple in construction and utilizes all commercially available components.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1138202
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  • 8
    Electronic Resource
    Electronic Resource
    The temperature and polymerization effects on the relaxation time and conductivity, and the evolution of the localized motions (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 6957-6965 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: To examine the manner in which molecular dynamics of a polymerizing liquid (stoichiometric amounts of 4,4′-diaminodicyclohexylamine and diglycidyl ether of bisphenol-A) evolves during thermal cycling from its (molecular) vitreous state to its fully polymerized vitreous state, calorimetry, and dielectric spectrometry were performed simultaneously in real time. The half-width of the relaxation spectrum of the liquid was relatively narrow and became narrower on heating. This was followed by an increase in the characteristic relaxation time and the spectrum became broader as polymerization occurred and reached completion. The dc conductivity initially increased and then decreased. The faster dynamics of the Johari–Goldstein relaxation in the fully polymerized state evolved as polymerization reached completion and the temperature increased. The dielectric polarization associated with this relaxation had a broad spectrum, whose half-width increased with decrease in the temperature. Its relaxation rate followed the Arrhenius equation with an activation energy of 63.4 kJ/mol. The temperature dependence of the faster relaxation did not change with the change in the overall configurational entropy of the liquid, a feature that substantiates the dynamic heterogeneity theories for the structure of the liquid and for the origin of the relaxation. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1311623
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  • 9
    Electronic Resource
    Electronic Resource
    Pumping-laser-fluence dependence of the time resolved fluorescence at 2.09 μm in Tm: Ho-YAG crystals
    Amsterdam : Elsevier
    Optical Materials 3 (1994), S. 157-161 
    Details
    ISSN: 0925-3467
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0925-3467(94)90020-5
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  • 10
    Electronic Resource
    Electronic Resource
    Heat capacity change on isothermal vitrification during a macromolecule's growth
    Amsterdam : Elsevier
    Physica A: Statistical Mechanics and its Applications 201 (1993), S. 95-100 
    Details
    ISSN: 0378-4371
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0378-4371(93)90404-R
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