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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial & engineering chemistry research 31 (1992), S. 901-908 
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Bean (Phaseolus vulgaris L.) cell suspensions were adapted for growth in 12 µM dichlobenil (2,6-dichlorobenzonitrile or DCB) by a stepwise increase in the concentration of the inhibitor in each subculture. Non-tolerant suspensions (I50 = 0.3 µM) gave rise to single cells or small clusters while tolerant cell suspensions (I50 = 30 µM) grown in DCB formed large clusters. The cells in these clusters were surrounded by a thick and irregular cell wall with a lamellate structure and lacking a differentiated middle lamella. Analysis of habituated cell walls by Fourier transform infrared spectroscopy and cell wall fractionation revealed: (1) a reduced amount of cellulose and hemicelluloses, mainly xyloglucan (2) qualitative and quantitative differences in pectin levels, and (3) a non-crystalline and soluble β-1,4-glucan. When tolerant cells were returned to medium lacking DCB, the size of the cell clusters was reduced; the middle lamella was only partly formed, and the composition of the cell wall gradually reverted to that obtained with non-tolerant cells. However, dehabituated cells (I50 = 12 µM) were 40-fold more tolerant to DCB than non-tolerant cells and were only 2.5-fold more sensitive than tolerant cells.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 107 (1999), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Cultures of bean (Phaseolus vulgaris L.) callus were adapted for growth in a 12 μM concentration of the herbicide isoxaben; 1 200-fold greater than the I50 calculated. Tolerant calluses grew slower, were browner and harder than nontolerant ones and formed large globular corpuscles on their surface. Cell wall fractionation of tolerant cells indicated that the mechanism of adaptation depends on the ability of these cells to divide and expand with a modified wall. The walls of tolerant cells growing on isoxaben differ from those of nontolerant cells by having reduced levels of cellulose and hemicelluloses and a higher uronic acid content. These differences are already found in adaptations to low concentrations of isoxaben and keep to the highest adaptation levels tested without any great change.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-198X
    Keywords: Key words Metabolic acidosis ; Growth ; Growth hormone ; Insulin-like growth factor-I ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Growth impairment induced by chronic metabolic acidosis is associated with an abnormal growth hormone (GH)/insulin-like growth factor-I (IGF-I) axis. To examine the potentially beneficial effects of IGF-I on acidosis-induced growth impairment and the influence of GH and IGF-I treatment on the GH/IGF-I axis, three groups of acidotic young rats (untreated, AC, n=12; treated with recombinant human GH, GH, n=8; treated with recombinant human IGF-I, IGF-I, n=8) were studied, and compared with nonacidotic rats fed ad libitum (C, n=9)) or pair-fed with the AC group (PF, n=12). After 14 days of acidosis and 7 days of treatment, growth rate, hepatic abundance of 4.7-kilobase (kb) and 1.2-kb GH receptor transcripts and 7.5-kb and 1.8- to 0.8-kb IGF-I transcripts, serum GH-binding protein (GHBP), and IGF-I concentrations (mean±SEM) were analyzed. Significant decreases of 4.7-kb GH receptor [26±2 vs. 49±6 arbitrary densitometry units (ADU)] and 7.5 kb IGF-I (41±3 vs. 104±10 ADU) transcripts and low serum GHBP (25±1 vs. 32±1 ng/ml) and IGF-I (279±50 vs. 366±6 nmol/l) levels were found in the AC compared with the C rats. The majority of these alterations were also observed in PF rats. Compared with acidotic untreated rats, GH and IGF-I therapy produced no improvement in growth rate. GH treatment normalized the levels of IGF-I mRNA, aggravated the acidosis-related inhibition of the GH receptor gene, and did not modify the serum levels of GHBP and IGF-I. In contrast, IGF-I administration depressed the hepatic expression of all GH and IGF-I transcripts and normalized serum IGF-I concentrations. Our results confirm that sustained metabolic acidosis alters the GH/IGF-I axis, in part because of associated malnutrition, and induced growth retardation that is resistant to GH therapy. Our study also shows that administration of IGF-I does not accelerate the growth of acidotic rats, suggesting a peripheral mechanism, at the level of target tissues, is responsible for the resistance to the growth-promoting actions of GH and IGF-I.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 31 (1985), S. 427-439 
    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 strategy for synthesizing regulatory control structures is developed within the framework provided by singular value decomposition (SVD). Quantitative measures of interaction and sensitivity for the nodes, as well as for the entire system, are established with this method. The approach enables analysis of the control struture over a range of frequencies which are of practical importance for a particular processing unit, thus insuring that both static and dynamic effects are encompassed. In addition, this method allows the designer to identify the modeling aspects which are important in determining the performance of the synthesized control structures. A series of examples, presented in order of increasing complexity, demonstrate the usefulness and versatility of this procedure. The technique is implemented as an interactive computer package.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2540-2554 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: For multiinput-multioutput nonlinear plants whose state-feedback control problem is solvable with complete or partial output linearization, the output-feedback problem is addressed by combining the state-feedback controller with a suitable closed-loop state inferer (detector). A candidate closed-loop detector was built to study the stability of the resulting plant-controller interconnection. As a result, sufficient conditions for closed-loop asymptotic nominal stability, as well as a systematic and simple design-tuning procedure, are obtained. The stabilization of an open-loop, unstable, free-radical homopolymerization reactor was studied as an application example.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1040-0397
    Keywords: Catalytic polarography ; Nickel ; 2-Methylbenzimidazole ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A comprehensive study of the prewave of NiII induced by 2-methylbenzimidazole in sodium barbital/nitric acid/potassium sulfate media was carried out by using various polarographic techniques in order to establish the mechanism via which the underlying electrode reaction proceeds. Based in the proposed mechanism, the formation of the catalytic complexes is a surface process involving deprotonated 2-methylbenzimidazole; the adsorption of this compound over the catalyst concentration where the prewaves are well-defined conforms to a Langmuir isotherm. Accordingly, a plot of the reciprocal of the limiting current for the prewave against the reciprocal of the ligand-catalyst concentration is a straight line. This finding was exploited for the determination of 2-methylbenzimidazole at concentrations from 5 × 10-7 to 5 × 10-5 M from NiII prepeaks recorded by differential pulse polarography and square-wave voltammetry.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1040-0397
    Keywords: Catalytic polarography ; CoII prewave ; Carbendazim ; Benomyl ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methyl 1H-benzimidazol-2-ylcarbamate (carbendazim or MBC) catalyzes the reduction of CoII at mercury electrodes in sodium barbital/nitric acid/sodium chloride media. On the basis of a detailed study of the CoII prewave induced by carbendazim, a mechanism for the electrode reaction is proposed and adequate conditions for the analytical determination of carbendazim by differential pulse voltammetry are established. Based on this finding, a voltammetric method for the indirect determination of methyl[1-(butylcarbamoyl)-1H-benzimidazol-2yl]carbamate (benomyl) is described, following the conversion of benomyl to carbendazim.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 43 (1997), S. 448-463 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Continuous solution copolymerization is an important industrial process in the manufacture of commodity and engineering plastics. The addition of comonomers and solvent, and the rate of heat exchange must be simultaneously manipulated to maintain safety, operability, and the product quality adequately, yielding a process with nonlinear behavior, strong and asymmetric input-output multivariable coupling, and potential for open-loop instability and state multiplicity, as shown in earlier dynamics and control studies. Accordingly, the key control objectives of the copolymerization reactor are: the compensation of interaction, the preclusion of input multiplicity and the robustness (i.e., tolerance to modeling and tuning errors) of the controller. In principle, these control issues should be considered within a nonlinear setting. Otherwise, the reactor may have to be operated with a conversion that is conservatively below what can be handled by standard mixing and heat-exchange equipment. To assess the inherent control possibilities and limitations of a given copolymerization reactor, a methodology to address the control problem is proposed such that the nonlinearity, interaction, input multiplicity, and robustness issues are explicitly confronted. The result is a linear multivariable interaction compensator whose tuning can be done with notions and tools from conventional control. This method is tested with the copolymerization of vinyl acetate with methyl methacrylate, dissolved in ethyl acetate.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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