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  • Wiley-Blackwell  (9)
  • Genetics Society of America (GSA)  (3)
  • American Association for the Advancement of Science  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 301-310 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper presents a theoretical study of the stability of chemical reaction on the external surface of a single spherical particle in stagnant surroundings. The analysis, which invokes methods of linear stability theory, yields necessary and sufficient conditions for stability of a steady state solution to small disturbances for the cases of very small and very large solid thermal conductivity. It is shown that heat losses from the solid surface may lead to transient behavior which is characteristically different from that for adiabatic surfaces, and that the unsteady state is strongly affected by the thermal capacity of the solid material. A numerical example is employed to illustrate the possible significance of unstable situations.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 12 (1966), S. 153-161 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An analysis of the stability of a plug-flow tubular reactor with recycle is presented for a model in which axial dispersion of heat and mass is neglected. A method is developed which permits determination of stability or instability for small disturbances immediately upon attainment of the steady state solution. The method, which is applicable to a large class of recycle processes, is based on a Newton-Raphson iteration technique for steady state solution and on the stability theory of nonlinear difference equations. The feasibility of the method is demonstrated by means of numerical examples which illustrate the occurrence of steady state multiplicity and unstable situations.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 25 (1979), S. 289-297 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Mathematical methods employed recently in a theoretical study by Uppal et al. (1974) are applied to the second-order homogeneous reaction between sodium thiosulfate and hydrogen peroxide and are combined with experimental investigations of that reaction using a nonadiabatic continuous stirred tank reactor (CSTR). A complete portrayal of the expected behavior of that reaction system is presented in parameter space. Some new experimental studies of reactor instabilities are presented and linked to that portrayal. Close agreement is shown between theoretical predictions and experimental data.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 16 (1970), S. 410-419 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Steady state and transient characteristics of an adiabatic, continuous flow, stirred reactor were studied in experiments employing the exothermic reaction between sodium thiosulfate and hydrogen peroxide in aqueous solution. Results illustrate the multiplicity of steady states in this system over a range of residence times. Temperatures of unstable states were attained experimentally by observing the effect of perturbations from stable temperatures. The observed steady states of the reactor under various mixing conditions are shown to be in good agreement with the predictions of a mathematical model which is based on the assumptions that mixing is perfect and that a single independent chemical reaction occurs. Less exact quantitative agreement between theoretical and experimental unsteady performance is accounted for in terms of the sensitivity of the unsteady state to small errors in the system parameters and the existence of appreciable extraneous heat capacities of the experimental equipment.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 16 (1970), S. 356-358 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An adiabatic loop reactor was operated at naturally unstable steady states in experiments employing the reaction between sodium thiosulfate and hydrogen peroxide in aqueous solution. The unstable states, the intermediate states in a multiple state regime, were stabilized by manual manipulation of the recycle ratio. Resulting temperature data agreed well with those predicted from a plug-flow model. Observations of the transient response to small disturbances from the intermediate states verified that they were indeed unstable as had previously been predicted theoretically. Cursory attempts to stabilize the system by means of automatic feedback control employing a three-mode controller were unsuccessful.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 13 (1967), S. 519-527 
    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 theoretical study of the transient state of a plug-flow tubular reactor with recycle is presenred for a model in which axial dispersion of heat and mass is negligible. A qualitative description of the temporal behavior near the steady state is obtained from an analysis of the linearized transient equations, and some large-scale transient characteristics are studied by means of numerical solution of the nonlinear transient equations. A cursory study of the application of the Liapunov's direct method to predict regions of asymptotic stability is also presented. Numerical examples illustrate sustained oscillatory behavior as well as the transient nature of systems with multiple steady states.
    Additional Material: 11 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 15 (1969), S. 670-679 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Steady state multiplicity in an adiabatic loop reactor was studied in experiments employing the reaction between sodium thiosulfate and hydrogen peroxide in aqueous solution. The steady state characteristics of the loop reactor were predicted by a method which utilized batch reactor data of temperature vs. time directly. The method was based on the assumption of plug flow with negligible axial dispersion and on a single-step chemical kinetic model. Experimental results verify the existence of multiple steady states on ranges of feed flow rates and recycle ratios and demonstrate the capability of the simple model for predicting the qualitative and quantitative features of the reactor steady state.Some observations were made of the effect of large disturbances on the stability of the reactor while operating in a multiple state region. Results for such cases illustrate reactor instability in the sense that a transition to a new steady state takes place provided the disturbance is sufficiently large.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Zwei Verfahren zur Darstellung α-trimethylsubstituierter Methylphosphane von genereller Anwendungsbreite werden vorgestellt. Phenylierte Vertreter PhPR—CH2—Tms (2a - ) lassen sich durch Na-Spaltung in NH3 und nachfolgende Kondensation mit Cl—CH2—Tms gewinnen. Metallierung mit n-BuLi und TmsCl—Einwirkung führt zur Zweitsilylierung in αPosition (3a - d, f. Diorganylamino-funktionelle Derivate 5a - e und 6 sind vorteilhaft über eine Primäraktivierung (Grignardierung oder Lithiierung) der Silylmethan-Komponenten zu erhalten. Die oxidative Ylidierung mit CCl4 ergibt nach Gl. (7) in allen Fällen P-Chlor-methylphosphorane. Außer durch Elementaranalyse wird die Konstitution sämtlicher Verbindungen durch die 31P{1H}- und komplementären 13C{1H}-Daten gesichert.Phosphorus-Carbon-Halogen Compounds. XXV. α-Trimethylsilyl-substituted Methylphosphanes: Synthesis and CCl4—Oxidation to P-Chlor-methylene-phosphoranesTwo procedures of general applicability for the synthesis of αxyltrimethylsilyl-substituted methylphosphanes are reported. Phenylated species PhPR—CH2—Tms (2a - e) can be obtained by Na cleavage in NH3 and subsequent condensation with Cl—CH2—Tms. Metallation with n-BuLi and treatment with TmsCl causes two-fold silylation in α-position (3a - d, f). Diorganylamino-functionalized derivatives 5a - e and 6 are preferrably prepared by initial activation (grignardation or lithiation) of the silylmethane component. Oxidative ylidation with CCl4 yields in all cases P-chloro-methylenephosphoranes according to eq. (7). The constitution of all compounds has been confirmed by 31P{1H} and complementary 13C{1H} data in addition to elemental analyses.
    Additional Material: 6 Tab.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 266-266 
    ISSN: 0570-0833
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 10
    Publication Date: 2016-07-08
    Description: Histone H1 variants, known as linker histones, are essential chromatin components in higher eukaryotes, yet compared to the core histones relatively little is known about their in vivo functions. The filamentous fungus Neurospora crassa encodes a single H1 protein that is not essential for viability. To investigate the role of N. crassa H1, we constructed a functional FLAG-tagged H1 fusion protein and performed genomic and molecular analyses. Cell fractionation experiments showed that H1-3XFLAG is a chromatin binding protein. Chromatin-immunoprecipitation combined with sequencing (ChIP-seq) revealed that H1-3XFLAG is globally enriched throughout the genome with a subtle preference for promoters of expressed genes. In mammals, the stoichiometry of H1 impacts nucleosome repeat length. To determine if H1 impacts nucleosome occupancy or nucleosome positioning in N. crassa , we performed micrococcal nuclease digestion in the wild-type and the $$\Delta $$ hH1 strain followed by sequencing (MNase-seq). Deletion of hH1 did not significantly impact nucleosome positioning or nucleosome occupancy. Analysis of DNA methylation by whole-genome bisulfite sequencing (MethylC-seq) revealed a modest but global increase in DNA methylation in the $$\Delta $$ hH1 mutant. Together, these data suggest that H1 acts as a nonspecific chromatin binding protein that can limit accessibility of the DNA methylation machinery in N. crassa .
    Electronic ISSN: 2160-1836
    Topics: Biology
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