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41.
42.
Eunice Valduga Alexsandra Valério Pihetra Oliveira Tatsch Helen Treichel Agenor Furigo Jr. Marco Di Luccio 《Food and Bioprocess Technology》2009,2(2):234-238
The increasing demand for carotenoids by industries has drawn attention to their bio-production. Since pigments are intracellular,
extraction steps are then needed after cell cultivation. In this work, different strategies for extraction of carotenoid pigments
from Sporidiobolus salmonicolor (CBS 2636) were studied. Different solvents (dimethyl sulfoxide, petroleum ether, hexane, ethyl acetate, chloroform, and
acetone), liquid N2, and diatomaceous earth were used to disrupt the cell and thus release the intracellular carotenoids. The results of this
study showed that when multiple solvents were used, a synergistic effect on the extent of carotenoids recovery was obtained.
Maximum concentration of total carotenoids (913 μg/L) was obtained in the treatment using liquid N2 and dimethyl sulfoxide to disrupt the cell, followed by the extraction with a solution of acetone/methanol (7:3, v/v). 相似文献
43.
Summary
The dielectric behaviour through DETA system has been studied for six PVC samples of distinct molecular microstructure in
terms of content and associated surroundings and conformation of the local configurations mmr termini of isotactic sequences. Both the dielectric studies and the microstructure of the samples, as obtained by stereospecific
substitution reaction of an additive-free commercial PVC are to be published in detail separately. For purposes of clarity
some of the results are mentioned in Experimental section.
The phenomenological correlation between the β parameter as defined by Ngai's theory and the microstructure of the samples,
quantities both issued from the above quoted work, is considered in the present paper with the objective of providing some
novel ideas on the physical meaning, at molecular level, of the Ngai's coupling parameter, in the light of mobility constraints
and local free volume associated with mmr structure at its likely conformations.
Received: 16 March 2001/Revised version: 18 June 2001/Accepted: 24 July 2001 相似文献
44.
45.
A social network perspective helps identify and analyse informal knowledge transfer among people and organisations with the
aim to recommend organisational interventions and improvements, for example in the form of Information and Communication Technology
(ICT) support. This paper particularly focuses on a key concept of social network analysis (SNA), the concept of tie strength,
in an inter-organisational knowledge transfer context. Tie strength describes the strength of a social relationship. In the
past, SNA literature with a knowledge management context has often emphasized the importance of strong and/or weak ties rather
than of intermediate (medium strong) ties in a social network. Nevertheless, in this study, intermediate ties are identified
as the dominant links among key groups of organisation in a social network. Intermediate ties also help connect otherwise
weakly linked organisations. Moreover, a definition of intermediate ties in the context of knowledge management is introduced.
With the help of cluster analysis and an investigation into the levels of reciprocity, intermediate ties can be clearly defined
in a social network. Due to their importance for knowledge transfer in a social network, intermediate ties should be primarily
supported, for example by appropriate ICT. 相似文献
46.
Leandro C. Silva Valéria V. Murata Carla E. Hori Adilson J. Assis 《Optimization and Engineering》2010,11(3):441-458
In this work three mathematical models for methane steam reforming in membrane reactors were developed. The first one is a
steady state, non isothermal, non isobaric and one dimensional model derived from material and energy balances and validated
using experimental data from the literature. It is referred as full model. The influence of two different intrinsic kinetics
available, as well as, the influence of five important parameters on methane conversion (XCH4_{\mathrm{CH}_{4}}) and hydrogen recovery (YH2_{\mathrm{H}_{2}}) were parametrically evaluated through simulations. The second model, referred as meta-model, was obtained though the response
surface technique. This meta-model was included into a constrained optimization problem solved using NPSOL. The third model,
referred as a simplified model, takes into account only mass balances from the full model. Using this model, a gradient based
method (DIRCOL) was used to perform the optimization of the sum of methane conversion and hydrogen recovery. High methane
conversions and hydrogen recoveries were reached through these methodologies. 相似文献
47.
Carrasco C Rosu F Gabelica V Houssier C De Pauw E Garbay-Jaureguiberry C Roques B Wilson WD Chaires JB Waring MJ Bailly C 《Chembiochem : a European journal of chemical biology》2002,3(12):1235-1241
The structural selectivity of the DNA-binding antitumor drug ditercalinium was investigated by competition dialysis with a series of nineteen different DNA substrates. The 7H-pyridocarbazole dimer was found to bind to double-stranded DNA with a preference for GC-rich species but can in addition form stable complexes with triplex and quadruplex structures. The preferential interaction of the drug with four-stranded DNA structures was independently confirmed by electrospray mass spectrometry and a detailed analysis of the binding reaction was performed by surface plasmon resonance (SPR) spectroscopy. The BIAcore SPR study showed that the kinetic parameters for the interaction of ditercalinium with the human telomeric quadruplex sequence are comparable to those measured with a duplex sequence. Slow association and dissociation were observed with both the quadruplex and duplex structures. The newly discovered preferential binding of ditercalinium to the antiparallel quadruplex sequence d(AG(3)[T(2)AG(3)](3)) provides new perspectives for the design of drugs that can bind to human telomeres. 相似文献
48.
The H2-norm control problem of discrete-time Markov jump linear systems is addressed in this paper when part of, or the total of the Markov states is not accessible to the controller. The non-observed part of the Markov states is grouped in a number of clusters of observations; the case with a single cluster retrieves the situation when no Markov state is observed. The control action is provided in linear feedback form, which is invariant on each cluster, and this restricted complexity setting is adopted, aiming at computable solutions. We explore a recent result by de Oliveira, Bernussou, and Geromel (Systems Control Lett. 37 (1999) 261) involving an LMI characterization to establish a H2 solution that is stabilizing in the mean square sense. The novelty of the method is that it can handle in LMI form the situation ranging from no Markov state observation to complete state observation. In addition, when the state observation is complete, the optimal H2-norm solution is retrieved. 相似文献
49.
For a company, information and communication system is a product of divergent rationalities which come to clash. Dissimilar logic leads to diverging projects : one focused on information aims to integrate and control its processing and flow rate, the other prefers to look at communication as a vector of working together among peers. However beyond these conflicts appears a factor of coherence and cohesion which ultimately helps the rationalities to join. A management able to combine integration of wage earners by identifying the objectives of the company and individualism (information systems is a vector of such a strategy). The goal is to avoid a major risk in form of mass action. The remaining question turns about the ability for innovation allowed to wage-earners in a company driven by standards and believes, in fact ideology. Sticking to standards, in other words conformity seems to leave out marginal handling and conflicting situation sources of innovative spirit. 相似文献
50.
S García-Asensio R Barrena S Guelbenzu J López del Val J Acha 《Canadian Metallurgical Quarterly》1998,26(152):621-624
INTRODUCTION: Hypophyseal hyperplasia is an uncommon disorder in which the gland increase in size due to excessive proliferation of strings of normal cells, which usually secrete prolactin. Different aetiologies may cause this disorder of the hypophyseal gland. However, in a small number of cases the hyperplasia is not due to any of these aetiologies and is therefore known as idiopathic hypophyseal hyperplasia. There are few references in the literature to idiopathic hypophyseal hyperplasia with hyperprolactinaemia. Usually diagnosis is reached after treatment for a hypophyseal adenoma, since the clinical features are similar. CLINICAL CASES: We present three cases seen in our department, in which hormone and endocrine studies were done to exclude known causes of hyperplasia, together with CT and MR scans. We analyzed the behaviour of hypophyseal hyperplasia by using imaging techniques, and the differential aspects with regard to hypophyseal adenomas. Firm diagnosis is only made on anatomopathological study of the hypophysis. However, we consider that sound knowledge of the characteristics of this condition may help to establish the correct diagnosis and thus avoid unnecessary surgery. CONCLUSIONS: We review the information published in the literature on this subject, emphasizing the importance of differential diagnosis by means of imaging techniques. 相似文献