Showing papers by "Polytechnic University of Valencia published in 1989"
TL;DR: Mixed model methodology was applied to estimate genetic trend of three rabbit strains (A, V and B) since there was no control line available and genetic trend was estimated by regression of generation average of genetic predictors on generation number.
156 citations
TL;DR: The concentration of proteolytic products was determined as free amino acids in the water-soluble fraction at two, four, seven and nine months of aging and at two different maturation temperatures (6°C, 15°C).
Abstract: Cheddar cheese was produced with different lactobacilli strains added to accelerate ripening. The concentration of proteolytic products was determined as free amino acids in the water-soluble fraction at two, four, seven and nine months of aging and at two different maturation temperatures (6°C, 15°C). All amino acids increased during ripening and were higher in the Lactobacillus- added cheeses than in the control cheese, and higher in cheeses ripened at 15°C than at 6°C. Glutamic acid, leucine, phenylalanine, valine and lysine were generally in higher proportion in all cheeses. The cheeses with added L. casei-casei L2A were classified as having a “strong Cheddar cheese” flavor after only seven months of ripening at 6°C.
116 citations
TL;DR: The degradation of some of these proteins by a constitutive endoproteolytic activity that co-distributes with pathogenesis-related proteins in the intercellular spaces of tomato leaves infected with citrus exocortis viroid is reported.
Abstract: As a response to the stress induced by different afflicting agents, tomato plants (Lycopersicon esculentum) produce the so-called ‘pathogenesis-related’ proteins. Here we report the degradation of some of these proteins by a constitutive endoproteolytic activity that co-distributes with pathogenesis-related proteins in the intercellular spaces of tomato leaves infected with citrus exocortis viroid. This endoproteinase was purified, showing a pH optimum of 2.5–3.5, a Mr of 37000 and selective inhibition by pepstatin. In crude homogenates, the enzyme does not seem to degrade other cellular proteins. This specificity indicates that the proteinase might be involved in the extracellular degradative pathway of pathogenesis-related proteins and in the regulation of their biological function.
84 citations
TL;DR: In this article, Lactobacillus strains were added as an adjunct to the regular lactic starter in Cheddar cheese manufacture in order to accelerate the ripening of Cheddar.
Abstract: Lactobacillus strains were added as an adjunct to the regular lactic starter in Cheddar cheese manufacture in order to accelerate ripening. Microbial cheese proteolysis resulted in the release of free amino acids which were extracted with the astringent and bitter fractions and separated by size-exclusion and reversed-phase HPLC chromatography. Lactobacillus strains generally increased the degree of proteolysis. L. plantarum and L. brevis produced off-flavors possibly due to an accumulation of medium-size peptides. The control cheese (without lactobacilli) had the most peptides with a mean molecular- weight of < 1000 daltons and had a flavor described as slightly bitter. Addition of L. casei-casei L2A accelerated ripening and yielded a well-aged Cheddar cheese without any bitterness even after 7 months at 6°C.
52 citations
TL;DR: In this article, a systematic study of the influence of ageing on the dynamic properties of amorphous poly(methyl methacrylate) (PPMA) has been made.
43 citations
TL;DR: The enzyme was present intra- and extracellularly, and the intracellular location was limited to the vacuole and was always associated with engulfed cell material.
Abstract: Citrus exocortis viroid induces in tomato plants (Lycopersicon esculentum) synthesis and accumulation of a pathogenesis-related protein (P69) previously reported to be a proteinase (Vera P, Conejero V [1988] Plant Physiol 87: 58-63). By immunogold/transmission electron microscopy, we have studied the distribution of this protein in thin sections of parenchymatous leaf tissue. The enzyme was present intra- and extracellularly. The intracellular location was limited to the vacuole and was always associated with engulfed cell material. When extracellularly located, the enzyme was associated with a dispersed, electron-dense material in the intercellular spaces. This latter location was confirmed after analysis of intercellular washing fluids obtained by vacuum infiltration of leaves. These observations provide new data for the understanding of viroid pathogenesis and the biological role of the pathogenesis-related proteinase P69.
35 citations
TL;DR: The results suggest that ethylene is a mediator of the induction of P69 proteinase by citrus exocortis viroid and that symptom severity is correlated with the accumulation and activity of this protein.
35 citations
TL;DR: In this article, the unique solution of the matrix equation AXB − CXD = E is obtained in explicit form by means of the inversion of an n X n or m X m matrix from the coefficients of the Laurent expansions of (λC − A)−1 and (λB − D) −1 and the relative characteristic polynomial of λC−A or λB −D respectively.
32 citations
TL;DR: In this paper, a comparative study of the dielectric relaxation spectra of poly(methyl acrylate), poly(ethyl acrylates), and poly(butyl acryls) was carried out, taking into account the spectra spectra for the corresponding polymers in the series of polymethacryls.
Abstract: A comparative study is undertaken of the dielectric relaxation spectra of poly(methyl acrylate), poly(ethyl acrylate), and poly(butyl acrylate), taking into consideration the spectra of the corresponding polymers in the series of the polymethacrylates. The three polymers, PMA, PEA, and PBA, present an α relaxation zone clearly separated from the secondary relaxations. Its shape is not altered with temperature, and it is possible to construct a master curve. With increasing length of the side chain, its distribution of relaxation times broadens and the temperature of the maximum of the relaxation decreases. A β relaxation with decreasing intensity as the length of the side chain increases is clearly perceptible in PMA and PEA, but almost not perceptible at all in PBA. In PEA this relaxation appears split into two peaks. Computer simulation of restricted motions of the side chain discard an origin similar to that of the γ relaxation in PPA or PBA for the lowest temperature component of the relaxation, and suggests the conjunction of two rotation mechanisms in this relaxation for the polyacrylates. For the experimental temperatures of our tests a γ relaxation shows up only in PBA. Its apparent activation energy, higher than in related polymers of the polymethacrylate series, suggests that the tighter packing of monomeric units in polyacrylates leads to a significant increase in the intermolecular contribution to the potential energy barrier responsible for the relaxation.
30 citations
TL;DR: Glutamic acid in cheese was determined by its reaction in a packed-bed enzyme reactor containing immobilized glutamate dehydrogenase (GIDH) in a flow-injection system, measuring fluorescence of NADH generated.
Abstract: Glutamic acid in cheese was determined by its reaction in a packed-bed enzyme reactor containing immobilized glutamate dehydrogenase (GIDH) in a flow-injection system, measuring fluorescence of NADH generated. There was a linear relationship (r = 0.999) between log-peak height and log-glumatic acid concentration (0.01 to 0.5 mM). The detection limit was 0.005 mM for an injection volume of 88 μX. The sample frequency was 30/h and the precision was better than 1.2% for 10 successive assays. The accuracy of the enzyme reactor-flow injection system was evaluated by comparison with HPLC results and an excellent correlation was obtained (r = 0.996). No measurable decrease in activity of the GIDH column was observed after a 3-month period.
24 citations
26 Sep 1989
TL;DR: A formal model of the algorithm's execution is developed, which enables us to prove its correctnes and prove a logarithmic upper bound on the average number of messages needed per critical section grant.
Abstract: In this paper we present a distributed algorithm for mutual exclusion. The algorithm maintains a dynamic forest structure in which the paths between nodes are compressed as a result of requesting the Critical Section. We develop a formal model of the algorithm's execution, which enables us to prove its correctnes. The formal model is also used to show that an execution history of the algorithm when concurrent requests are made (the ususal case) is equivalent to a history in which the requests are made serially. Based on this fact we are able to prove a logarithmic upper bound on the average number of messages needed per critical section grant.
TL;DR: In this article, a systematic study of dielectric spectrum on a series of high and low density commercial polyethylenes has been performed, and the authors have observed that both γ and α dielectrics relaxations zones are formed by two overlap relaxations which have been labeled γII, γI, and α′, and γ respectively, in order of increasing temperatures.
Abstract: A systematic study of dielectric spectrum on a series of high and low density commercial polyethylenes has been performed. Every polyethylene was characterized by determination of molecular weight distribution, the number of functional groups: ketone, aldehyde, vinyl, vinylidene, trans-vinylene, the fraction crystalline, and the degree of branching. We have observed that both γ and α dielectric relaxations zones are formed by two overlap relaxations which have been labeled γII, γI, and α′, and α respectively, in order of increasing temperatures. The intensity of the dielectric spectrum of all polyethylene depends over and above other parameters on the number of the carbonyl groups formed as a result of irradiation. This number is different for every polyethylene even when they receive the same dose of irradiation (20 Mrad). However, the participation of carbonyl groups in the γI and α′ dielectric relaxations decreases with the total crystalline content of each polyethylene. The α dielectric relaxation position in the temperature axis is governed by the most probable crystallite thickness.
TL;DR: In this article, the reachability and controllability properties for discrete-time positive periodic systems were studied and the equivalence between N -periodic systems and invariant systems, with n states and m inputs, was shown.
TL;DR: In this article, the dynamic-mechanical spectrum of irradiated and unirradiated high and low density polyethylenes contains the γII-, γI-, β-, αI-, αII-, and αIII- relaxations, in order of increasing temperature.
Abstract: A study of the dynamic-mechanical relaxation spectrum in a series of commercial high and low density polyethylenes (Dow Chemical), irradiated as well as unirradiated, and subjected to different annealing process, has been performed. The effect of 20-Mrad dose of irradiation on the chemical structure has been analyzed and an increase in the number of aldehyde, ketone, and transvinylene groups and a decrease in the number of vinyl and vinylidene groups has been observed. The dynamic-mechanical spectrum of irradiated and unirradiated high and low density polyethylenes contains the γII-, γI-, β-, αI-, αII-, and αIII- relaxations, in order of increasing temperature. It has been observed that γ-irradiation followed by annealing modified the intensity and the position of relaxations in these polyethylenes.
TL;DR: In this article, a method for the determination of Cl −, HPO 2 − 4 and SO 2 −4 by ionic chromatography in a sugar-rich model system is proposed.
TL;DR: In this article, the pole-placement problem for the monodromy matrix of a discrete-time linear periodic system is considered, and the result obtained by Wonham (1979) is extended to the periodic case.
Abstract: The pole-placement problem for the monodromy matrix of a discrete-time linear periodic system is considered. Given a partition of the complex plane into a ‘good’ part ℂ and a ‘bad’ part ℂb, the result obtained by Wonham (1979) is extended to the periodic case. This extension is based on the decomposition of a completely controllable periodic system into two subsystems, such that the first subsystem is completely reachable and the eigenvalues of the monodromy matrix of the second one are equal to zero.
TL;DR: A structural relaxation process similar to that in amorphous polymers has been found in poly(γ-benzyl- l -glutamate) and its kinetics has been determined by differential scanning calorimetry and modelled using a phenomenological model as mentioned in this paper.
TL;DR: In this paper, the authors used the 1,2-dimethoxybenzene (Ver) as a donor and tetracyanoethene (TCNE) as an acceptor from the dark blue charge transfer complex Ver·TCNE.
01 Jan 1989
TL;DR: In this article, the authors considered weighted inductive limits of type VC(X) and their projective hulls CV(X), as well as on the recent contributions of F. Bastin [1] and D. Vogt [13] and reported that two general questions which had been open for some time have rather satisfactory answers now.
Abstract: We report on the part of our article [4] which deals with weighted inductive limits of type VC(X) and their projective hulls CV(X), as well as on the recent contributions of F. Bastin [1] and D. Vogt [13]. Two general questions which had been open for some time have rather satisfactory answers now:
1.
If V = (vn)n is a decreasing sequence of continuous weights on a kIR-space X, VC(X) must always be complete.
2.
Let V denote a decreasing sequence of continuous weights on a completely regular Haus-dorff space X and V = V(V). (Then CV(X) is a (DF)-space.)
TL;DR: In this article, the authors used the theory of non-elastic deformation based on a specific model for the mobility in amorphous polymers, and obtained an equation including the real and imaginary parts of the complex modulus and the heat capacity as a function of temperature and ageing time.
Abstract: Using the theory of non-elastic deformation based on a specific model for the mobility in amorphous polymers, an equation was obtained including the real and imaginary parts of the complex modulus and the heat capacity as a function of temperature and ageing time. Thus, the model is based on the calculation of time and temperature evolution of the population of “faults” (corresponding to an excess of enthalpy and entropy) in the structure. We employ the model with only one “characteristic” relaxation time obtained from a concept of hierarchical correlation. The parameters appearing in the equations for G* and cp are the same in each case and are obtained from classical experiments (mechanical spectroscopy, dilatometry, calorimetry, etc.), thus having a specific physical meaning. Dynamic loss tangent and specific heat of PMMA measured after different thermal histories involving isothermal ageing agrees quite well with the prediction of the model.
TL;DR: In this article, the authors investigated tomato production in tomato cultures infected with citrus exocortis viroid (CEV) and showed that it is possible to produce ethylene in tomato culture infected with CVC.
Abstract: (1989). Ethylene production in tomato cultures infected with citrus exocortis viroid (CEV) Canadian Journal of Plant Pathology: Vol. 11, No. 3, pp. 256-262.
TL;DR: The dielectric relaxation zone of a low-density polyethylene has been studied by thermally stimulated depolarization currents (TSDC) and thermal sampling (TS) and three relaxations have been found in this zone, which have been labeled γI, γII and γIII in decreasing order of temperature.
Abstract: The dielectric relaxation zone of a low-density polyethylene has been studied by thermally stimulated depolarization currents (TSDC) and thermal sampling (TS). Three relaxations have been found in this zone, which have been labeled γI, γII, and γIII in decreasing order of temperature. Samples of different crystallinities were subjected to several thermal treatments in order to study the molecular origin of each relaxation. The γI relaxation intensity changes with the thermal treatment, while the intensity of the γI relaxation is only slightly modified. Using TS it has been proved that the γI relaxation fulfils the compensation law with a high level of significance. Nevertheless, the experimental data are not enough to verity the γI and γIII relaxation.
TL;DR: The photolysis of the 7-acetoxybenzopyran derivatives 1a-5a has been carried out as mentioned in this paper, where chromene 1a was found to undergo extensive photopolymerization.
TL;DR: A review of the components of the automation process and the way they can be handled under a low cost point of view is presented.
01 Jun 1989
TL;DR: In this article, the duality theorem of Buchwalter can be applied to obtain a ( gDF )-space and hence is a gDF-space (cf., Ch. 12 or 3, Ch. 8]).
Abstract: By the work of Taskinen (see [4, 5]), we know that there is a Frechet space E such that L b ( E , l 2 ) is not a ( DF )-space. Moreover there is a Frechet–Montel space F such that is not ( DF ). In this second example, the duality theorem of Buchwalter (cf. [2, §45.3]) can be applied to obtain that and hence is a ( gDF )-space (cf. [1, Ch. 12 or 3, Ch. 8]). The ( gDF )-spaces were introduced by several authors to extend the ( DF )-spaces of Grothendieck and to provide an adequate frame to consider strict topologies.
01 Nov 1989
TL;DR: In this paper, the spin densities n of CT-complexes were evaluated from EPR measurements in the temperature range of 5-400 K. Correlations between donor/acceptor combinations, electrical, magnetic and structural properties were discussed.
Abstract: Spin densities n of CT-complexes Vn 2 E 2 •TCNQ and Vn 2 E 2 •DDQ [Vn 2 E 2 =2,3,7,8-Tetramethoxychalkogenanthrene («5,10-Dichalkogena-cyclo-diveratrylene») with E=S, Se; TCNQ=7,7,8,8-Tetracyanoquinodimethane; DDQ=2,3-dichloro-5,6-dicyanoquinone] are evaluated from EPR measurements in the temperature range of 5-400 K. Three temperature regions with different slopes of ln n vs. 1/T are found. Correlations between donor/acceptor combinations, electrical, magnetic and structural properties are discussed
TL;DR: In this article, a hierarchical scheme for the supervision level in adaptive control implementation has been conceived, where the supervisory function is realized by an Expert System which has been developed in such a way that allows the treatment of both volatile an permanent data.
TL;DR: In this paper, a phenomenological model for combustion in direct-injection diesel engines is presented, based on the analysis of the fuel evolution from the injection start till the combustion end.
01 May 1989
TL;DR: In this article, the results obtained are presented and analyzed in terms of discharge coefficients, angular momentum flux and paddle-wheel speeds, calculated by integration of the measured velocity field in the case of the hot-wire results.
Abstract: The aerodynamic behaviour of the intake pipes of direct injection diesel engines has usually been quantified by means of swirl number and the discharge coefficient. In order to validate these parameters an experimental method based on the hot-wire technique has been applied to the steady flow rig where the former parameters are measured. This method allows the measurement of the three components of the velocity referred to an orthogonal coordinate system by placing the probe parallel to these three directions. The results obtained are presented and analysed in this paper. The comparison between the two measurement techniques has been done in terms of discharge coefficients, angular momentum flux and paddle-wheel speeds, calculated by integration of the measured velocity field in the case of the hot-wire results. The comparison between the values of the angular momentum flux allows the conclusion to be made that some of the hypotheses assumed by the paddle-wheel method are not accurate.