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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 8531-8535 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The Stanford Linear Accelerator Center is currently operating with a photocathode electron gun (PEG) to produce polarized electrons for its experimental program. Bunch intensities of up to 1011 electrons within 2 ns (8 A) are required from the electron gun. Operation of PEG has demonstrated a charge limit phenomenon, whereby the charge that can be extracted from the gun with an intense laser beam saturates at significantly less than 1011 electrons (the expected space-charge-limited charge) when the photocathode quantum efficiency is low. Studies of this charge limit phenomenon observed with a GaAs photocathode are reported.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Czechoslovak journal of physics 41 (1991), S. 272-276 
    ISSN: 1572-9486
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract After a description of the design and layout of the 2 kJ/5 TW single beam Asterix IV iodine laser the steps necessary for obtaining a laser beam intensity profile as homogeneous as possible are reported. These steps are: providing a homogeneous inversion density profile in the amplifiers by an appropriate flashlamp-reflector geometry and by compensating the edge enhancement caused by the image relaying system by suitable soft apertures. The paper concludes with a description of the results obtained by the laser system with the end-amplifier not in operation. The full system will become operational at the end of 1990.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1434-6079
    Keywords: 82.50.−m
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The small absorption is a major problem in isotopically selective IR multiphoton dissociation. Usually the radiation diverges before it is fully absorbed. To solve this problem, we have demonstrated the application of a refocusing (Herriott) multipass cell. It can generally help in laser isotope separation to use the photons more efficiently. Employing such a cell and a Q-switched CO2 laser at high repetition rate, the dissociation yield of CHCIF2 was 23 times higher than in a single pass. The number of passes used (up to 60) was more than is conventionally possible in such small cells. The increased number was permitted by making use of spherical aberration. With 18 passes, we also measured the multiphoton absorption for various wavelengths and pressures, in part separately for12CHCIF2 and13CHCIF2, and also for two-wavelength irradiation. Appropriate change of pressure or wavelength increased the absorption. But the corresponding increase of the dissociation was larger in every case. To explain this and other observations, we invoke the molecular distribution over the energy levels.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 10 (1990), S. 41-48 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Five cellulases were fractionated from a commercial cellulase preparation (CelluclastTM) Two isoenzymes of cellobiohydrolase I (CBHI)(pI = 4.1) could be proved to be real exo-glucanases due to their activity towards MU (=methylumbelliferyl)-lactoside being inhibited by cellobiose (5 mM) and due to production of cellobiose from carboxymethylcellulose (CMC) as the sole final product.Two isoenzymes of CBHII (pI=6.15, 6.0) were shown to act as endo-glucanases because they produced glucose, cellobiose and cellotetraose from CMC and because they were not inhibited by cellobiose when decomposing MU-lactoside. Results confirm recent reports in the literature classifying CBHI and CBHII as exo-type and endo-type cellulases, respectively. Both the CBHI and the CBHII isoenzymes were shown to be active towards CMC and amorphous cellulose.CBHI and CBHII reactions could be differentiated from one another by the velocities of decomposition of CMC: CBHI acts slowly and linearly whereas CBHII acts strongly and exponentially.The fifth of the purified enzymes must be classed as a conventional endoglucanase which exhibits activity towards CMC but fails to be active towards MU-lactoside and amorphous cellulose.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 11 (1991), S. 279-286 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Decompositions of amorphous cellulose induced by cellulases of Trichoderma reesei were evaluated from gradients at zero time of exponential functions which were fitted to nephelometrically measured values of turbidty of incubated solutions of cellulose [turbidity = A × exp (B × t)+ C [A, B, C = constants, t = time]]. Synergistic enhancements of decomposition of amorphous cellulose resulted in the range of 300 p.c. whenever of the two isoenzymes of cellobiohydrolase I of Trichoderma reesei (CBH I, being an exo-glucanase) one was incubated together with one of the isoenzymes of CBH II (being really an endo-glucanase). Accessibility of amorphous cellulose to enzymatic decomposition being calculated from the fitted function by the term (A/(A + C)) × 100 [p.c.] resulted for the CBH I isoenzymes and for the CBH II/1 in the range of 27 to 38 p.c. of the total substrate. Incubations of CBH II/1 in with CBH I/1 and CBH I/2 were followed by increases of accessibility to 85 and 87 p.c., respectively. CBH II/2 by itself caused a substrate accessibility in the range of 80 p.c., which increased to 96 p.c. when it was incubated together with CBH I/1 or CBH I/2. Amorphous cellulose dispersing activity (ACD activity) being evaluated from the fitted function by the term (A + C)/(Ac + Cc) × 100 [p.c.] (Ac + Cc × control turbidity at zero time) was not increased when a CBH I isoenzyme was incubated together with a CBH II isoenzyme. EG I, a convetional endo-glucanase from Tr. reesei proved not to act synergistically in any case when incubated together with one of the CBH isoenzymes. On the contrary, EG I turned out to act antagonistically to CBH II/1 and CBH II/2. Results can be interpreted as an exo-endo-synergism taking place between C1-specific exo- and endo-glucanases.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 11 (1991), S. 359-365 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: WHATMAN 1 CHR filter paper manufactured from macerated cotton fibers was shown to be a soft substrate when broken down by purified cellulases of Trichoderma reesei (CELLUCLAST). Destruction of filter-paper disks was induced by CBH I/1, CBH I/2, CBH II/1, CBH II/2, and EG I in a macroscopic assay. Attack on disks by mixtures of these cellulases (CBH I/1 or CBH I/2 mixed with CBH II/1, CBH II/2, or with EGJ) were followed by synergistically enhanced destructions.SCHLEICHER &SCHUELL filter paper No 595 was shown to be a harder substrate of enzymatical decomposition when induced by cellulases of CELLUCLAST. None of the cellulases could induce macroscopic destruction of filter-paper disks when acting in isolation. However, mixtures of isolated exo and endo-glucanases (CBH I/1 or CBH I/2 mixed with CBH II/1, CBH II/2, or EG I) caused powerful destruction of filter-paper disks.SCHLEICHER &SCHUELL filter paper No 595 incubated first with an endo-glucanase (CBH II/1, CBH II/2, EG I) and treated in a secondary incubation with an exo-glucanase (CBH I/1, CBH I/2) were destroyed to a greater extent than with incubations executed in the reverse order. Results confirm the endo exo concept of explaining cellulose decomposition.The filter-paper destruction assay was performed with filter-paper disks prepared with an office punch. Disks were incubated in 1 ml EPPENDORF reaction tubes filled up beforehand with 0.4 or 0.5 ml of enzyme solution. The degree of synergism of cellulases resulted from the assay in the range of 300 to 1 300 p.c.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two isoenzymes of cellobiohydrolase I (CBHI/1 and CBHI/2) of Trichoderma reesei purified from CelluclastTM are shown to cause a new mode of reaction which is exhibited additionally to the known exo-glucanase reaction of CBHI: Dispersion of amorphous cellulose solution is increased by CBHI/1 and CBHI/2 to 49 and 64 p.c., respectively, before decompositions of substrate as induced by the same enzymes become detectable. Amorphous-cellulose dispersing activity of CBHI is reduced by cellobiose which is known to be an inhibitor of CBHI. Amorphous-cellulose dispersing activity was also observed of a CBHII isoenzyme (CBHII/2), an endo-glucanase and complete Celluclast, however, to lesser extents (17, 12, 35 p.c., respectively). Observations with a phase-contrast microscope determined an increase of dispersion of particles of amorphous cellulose induced by cellulases of Celluclast. Decompositions of amorphous cellulose run almost linearly and quite exponentially when induced by CBHI and CBHII, respectively, allowing differentiation between exo-glucanase and endo-glucanase activities of these cellulases.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 593 (1991), S. 200-206 
    ISSN: 0044-2313
    Keywords: BiI3—HgI2 system ; BiI3—I2 system ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigations on the Barogram and Melting Diagram of the Systems BiI3—HgI2 and BiI3—I2The barograms of the systems BiI3—HgI2 and BiI3—I2 are determined by total pressure measurements in a membrane manometer. The melting diagrams follow from DTA measurements and the barogram. Both systems are eutectic with eutectica at 1.5 mol% BiI3 and 110°C for BiI3—I2 and 9 mol% BiI3 and 243°C for BiI3—HgI2.
    Notes: Die Zustandsbarogramme der Systeme BiI3—HgI2 und BiI3—I2 wurden durch Druckmessungen im Membrannullmanometer ermittelt. Die Schmelzdiagramme wurden aus DTA-Messungen und den Barogrammen aufgestellt. Beide Systeme sind einfach eutektisch mit Eutektika bei 1,5 Mol-% BiI3 und 110°C für BiI3—I2 und 9 Mol-% BiI3 und 243°C für BiI3—HgI2.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 601 (1991), S. 83-92 
    ISSN: 0044-2313
    Keywords: Bismuth triiodide ; decomposition equilibrium ; transport equilibrium ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigations on the Decomposition Equilibrium BiI3 ⇌ BiI + I2 and Transport Equilibrium 2Bi + BiI3 ⇌ 3BiIWe determined the decomposition equilibrium (1) and the transport equilibrium (2) by a membranezeromanometer and by CTR experiments. The enthalpy of formation for BiI was concluded from the equilibrium constants. With the standard entropy \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm S}^{\rm 0} ({\rm BiI, g, 298}) = 65.8 \pm 0.2\,{\rm cal/K} \cdot {\rm mol} $$\end{document} follow the values \documentclass{article}\pagestyle{empty}\begin{document}$$ \Delta {\rm H}_{\rm f}^0 ({\rm BiI, g, 298}) = 20.1 \pm 4\,{\rm kcal/mol} $$\end{document} from the first, and \documentclass{article}\pagestyle{empty}\begin{document}$$ \Delta {\rm H}_{\rm f}^0({\rm BiI, g, 298}) = 22.0 \pm 2\,{\rm kcal/mol} $$\end{document} from the second equation, by both methods.
    Notes: Das Zersetzungsgleichgewicht BiIl3, g = BiI, g + I2, g (1) und das Transportgleichgewicht 2Bi, fl + BiI3, g = 3BiI, g (2) wurden im Membrannullmanometer gemessen und letzteres auch durch chemische Transportreaktionen ermittelt. Aus den Gleichgewichtskonstanten wurde die Bildungsenthalpie des BiI, g hergeleitet. Man erhält mit der Standardentropie \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm S}^{\rm 0} ({\rm BiI, g, 298}) = 65,8 \pm 0,2\,{\rm cal/K} \cdot {\rm mol} $$\end{document} aus ersterem Gleichgewicht \documentclass{article}\pagestyle{empty}\begin{document}$$ \Delta {\rm H}_{\rm B}^0 ({\rm BiI, g, 298}) = 20,1 \pm 4\,{\rm kcal/mol,} $$\end{document} und aus letzterem nach beiden Herleitungen \documentclass{article}\pagestyle{empty}\begin{document}$$ \Delta {\rm H}_{\rm B}^0 = 22,0 \pm 2\,{\rm kcal/mol}{\rm .} $$\end{document}.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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