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  • Analytical Chemistry and Spectroscopy  (358)
  • Chemical Engineering  (180)
  • SPACE RADIATION  (179)
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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 10 (1987), S. 191-200 
    ISSN: 0935-6304
    Keywords: Liquid chromatography, HPLC ; Dead time calculation ; Homologous series ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A mathematical method for the calculation of the dead time (tm) in HPLC was evaluated using a computer simulation approach, in which artificial perturbations were introduced to Simulated homolog retention times. The calculation was based on a modified and extended Grobler and Bálisz (GB) method. Investigated wav how the precision of the calculated tM is affected by: statistical fluctuations in retention times and which, and how many homolog retention times are used. Based on these simulations a two-step procedure for the tM calculation is proposed: In the first step the linearity of log tR, n vs carbon number n is checked using as many homolog retention times as possible. The slope value bo of the first linear regression in the GB method is used for the selection of homolog retention times in the final tM calculation. In the second step the optimal selection of homologs is made and the final tM calculation is carried out. Guidelines for homolog selection are given.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 11 (1978), S. 493-498 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A series of α-oxobenzimidazolinic merocyanines differently substituted on the ‘phenolate’ part and bearing a paraffinic chain on one heterocyclic nitrogen, has been studied by 13C NMR. Electron donating substituents bring about an increase of the electronic density on the 3 methine carbon and an increase of the alternation of electron density on the 3,4-dimethine bridge. A bathochromic shift of the lower energy electronic transition is also observed. Furthermore, the low field resonance of the 3 methine proton is probably due to a specific interaction between this proton and the ‘phenolate’ oxygen atom. This implies the existence of a favoured trans configuration for merocyanine dyes.
    Notes: Une série de mérocyanines α-oxo benzimidazoliniques diversement substituées sur la partie ‘phénolate’ et possédant une chaǐne grasse sur l'un des azotes hétérocycliques, a été étudiée en RMN du carbone- 13. Des substituants donneurs d'électrons provoquent une augmentation de la densité électronique sur le carbone méthinique C-3 et une augmentation de l'alternance de la distribution de charge sur le pont diméthinique 3,4. Corrélativement un déplacement bathochrome de la transition électronique de plus basse énergie est observé. Par ailleurs, l'apparition de la résonance à champ faible du proton méthinique H-3 semble due à une interaction spécifique intervenant entre ce proton et l'atome d'oxygène ‘phénolate’, ce qui suppose l'existence d'une configuration trans privilégiée pour les mérocyanines.
    Additional Material: 1 Ill.
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  • 3
    Publication Date: 2019-06-28
    Description: The fragmentation of a 225 MeV/n O-16 beam was investigated at the Bevalac. Preliminary cross sections for mass = 13, 14, 15 fragments are used to constrain the nuclear excitation functions employed in galactic propagation calculations. Comparison to cosmic ray isotonic data at low energies shows that in the cosmic ray source C-13/C approximately 2% and N-14/0=3-6%. No source abundance of N-15 is required with the current experimental results.
    Keywords: SPACE RADIATION
    Type: OG-4.3-2 , 19th Intern. Cosmic Ray Conf - Vol. 2; p 80-83; NASA-CP-2376-VOL-2
    Format: application/pdf
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2603-2613 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A dynamic model of five-stage (C+D)EDED bleach plant was developed using SIMNON a dynamic simulation language developed at Lund Institute of Technology, as a platform. The model is composed of individual modules that represent each bleaching stage. Each module includes chemical addition and mixing, diffusion and reaction in a retention towel, and washing. These unit operations are coupled with chemical kinetics for each bleaching stage using appropriate models. A relationship between the (C+D)E Kappa number and the input absorption coefficient to the D1 stage was used to link the delignification and brightening partial sequences of the bleach plant. The model, verified using steady-state data, was used to model the dynamic response of the plant to step changes in production rate, (C+D) chemical addition, and incoming Kappa number, as well as the open-loop response of the plant to a simulated variation in incoming Kappa number. The modular structure of the program allows a variety of bleach plants to be assessed once flow parameters and chemical kinetics are known. The dynamic model can also be used to develop and compare control strategies before being implemented at the mill.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Publication Date: 2011-08-12
    Description: Spectral properties of celestial X ray objects near galactic center from balloon observation, noting supernova origin and magnetic bremsstrahlung emission mechanism
    Keywords: SPACE RADIATION
    Type: ; ADEMIE DES SCIENCES
    Format: text
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  • 6
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 29 (1989), S. 479-487 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The performance of screws of advanced design in injection molding has been investigated with respect to four different objectives: (1) improvement of distributive mixing; (2) improvement of dispersive mixing; (3) increase of plasticating capacity; and (4) reduction of inhomogeneity of melt temperature.The screws used are three zone screws with different compression ratios, screws with pineapple or Maddock/Egan mixing elements, with one or two channel barrier sections, with static mixers mounted in the valve or in the nozzle, or with combinations of these different elements. The best mixing quality is obtained with multi-channel Maddock sections. The highest plasticating capacity and, consequently, the shortest cycle times are achieved with the barrier screws. Temperature measurements show that these screws improve melt homogeneity considerably with a relatively small loss of plasticating time. In all cases, increasing the back pressure gives inferior results compared with improvement of the screw design.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 860-869 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In the development of advanced composite materials, the mechanical behavior of the matrix is of critical importance. The next generation of composite materials will be based on high modulus tough matrices, of which poly(aryl ether ether ketone) [hereinafter, referred to as PEEK] is one of the first crystalline thermoplastics to receive serious attention. As in all crystalline polymers, the matrix is itself a composite material whose properties depend significantly on the crystalline morphology developed during processing. In this contribution, the current understanding of crystallization in PEEK and its influence on mechanical properties is reviewed. Problems yet to be resolved are highlighted.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 321-327 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Increasingly widespread usage of stable isotope tracers to aid clinical diagnosis and support basic research has stemmed from both advances in mass spectrometry and the availability of competitively priced labelled compounds. Stable isotopes have been used generally to investigate normal and abnormal metabolic pathways, to estimate energy expenditure and body composition and to quantitate substrate flux and oxidation rates. Despite the fact that the underlying principles relating to the use of stable isotopes for in vivo studies are straightforward, careful consideration must be given to all aspects of human studies. This review highlights some of these, including choice of label and tracer molecule, mode of tracer administration and sampling site, analytical instrumentation, interpretation of data and ethical constraints.
    Additional Material: 1 Ill.
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  • 9
    ISSN: 0886-9383
    Keywords: Derivatization reaction ; Factorial design ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A number of nucleophiles have been successfully identified and quantified using the Kröhnke reaction with 2,3-diphenyl derivatives of quinolizinium salts. Optimization of the reaction conditions by means of a mathematical model involving analysis of the response surface has led to a better understanding of the factors exerting an influence on the above reaction.The parameters chosen were temperature, reaction time, base concentration, water concentration and nucleophile concentration. The reaction was developed in polar aprotic solvents (acetone, acetonitrile). To facilitate the nucleophilic attack, the presence of an organic base (triethylamine) was necessary, although concentrations in excess of 0·15M did not alter the development of the reaction. Since pharmaceutical solutions are often aqueous, the influence of water on the reaction was studied. Low water volumes have no significant influence on the opening of the quinolizinium ring by the nucleophilic reagent. However, when the water proportion exceeded that of the organic solvent, the fluorescence intensity was lower than expected. Development of the fluorescent reaction product was first detected 5 min after the reaction started. The fluorescence intensity reached its optimum value after 138 min.
    Additional Material: 2 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 36 (1990), S. 1613-1616 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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