146 resultados para Llenguatge i llengües


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Bacteria isolated from the rhizosphere of mulberry (Morus indica) as well as from control soil were tested for their effects on the growth of mulberry seedlings and for phytohormone production. About 12.8 per cent of the rhizosphere and 9.7 per cent of the soil isolates produced phytohormones in cultures. Rhizosphere isolates were more active in hormone synthesis than their soil counterparts. Soaking mulberry stem cuttings in culture filtrates of phytohormone synthesisers hastened their rooting. Culture filtrates of many isolates — hormone producers or not — stimulated or inhibited the growth of shoot and/or root of plants. Many cultures could also inhibit the germination of mulberry seeds.

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The hydrolysis of cupric ion has been studied at various ionic strengths (0·01, 0·05, 0·1 and 0·5 M). The results are analyzed employing 'core + links' theory, log-log plot, normalization plot, and extrapolation method for obtaining the pure mononuclear curve. The stability constants of Cu2(OH)2++, Cu3(OH)4++, Cu(OH)+ and Cu(OH)2 have been reported.

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ESR investigations on dilute single crystals of dibarium copper formate tetrahydrate, at room temperature and 90° K. have been described. A general method used for the evaluation of theg-tensor in this triclinic crystal, which contains only one ion in the unit cell, has been discussed. A detailed account of the evaluation of the quadrupole interaction is given. Expressions for the positions of the hyperfine levels of the lowest Kramer’s doublet of the Cu++ ion in the magnetic field have been worked out for the case when B and Q are of similar magnitude.

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Trace elements zinc, copper, manganese, molybdenum and cobalt have been shown to have varying effects on growth and trace element composition of the silkworm. Results indicate the important role of manganese in the normal metabolism of the insect. Cobalt has been shown to exert a very favourable effect on growth and silk yield.

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The occurrence of an enzyme hydrolyzing flavine adenine dinucleotide (FAD) was demonstrated in a number of seed extracts. The enzyme from Phaseolus radiatus was purified 104-fold by fractionation with ammonium sulfate and ethanol and by negative adsorption on alumina Cγ gel. The enzyme cleaves the POP bond of FAD to yield flavine mononucleotide and adenosine monophosphate. When reduced glutathione is added to the enzyme, it cleaves FAD at the COP bond to yield riboflavine, adenosine, and pyrophosphate, Both the activities are optimal at a pH of 7.2 and at a temperature of 37 . The Km for both the activities is 1.65 × 10−5 M. The stoichiometry and the identity of the products of both the treated and untreated enzyme were established. The untreated enzyme was not inhibited by pCMB or arsenite, but the treated enzyme was sensitive to both these inhibitors. The inhibition by pCMB could be reversed by monothiols and the inhibition by arsenite by dithiols.

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1. A detailed polarographic study of cadmium has been made employing glycine, α-alanine, β-alanine, valine, aspartic acid, glutamic acid and asparagine as complexing agents at various pH values. The effect of incorporating sodium hydroxide, sodium carbonate and ammonium nitrate + ammonium hydroxide, on the polarographic behaviour of amino acid complexes of cadmium has also been investigated. 2. The reduction process has been found to be reversible in all systems. 3. The small shifts in the half-wave potentials noticed due to increase in the concentration of sodium hydroxide and sodium carbonate in presence of amino acids have been explained on the basis of formation of mixtures of pure and mixed amino acid complexes of cadmium. Mixed complexes have also been noticed in presence of ammonium hydroxide and ammonium nitrate and amino acids. 4. Polarographic evidence has been obtained for the formation of over 30 pure and mixed complexes. The dissociation constant Kd, the Δ F° value for the dissociation, and standard potential value for the formation, of each complex have been computed. 5. It has been found that cadmium can be polarographically estimated in amino acid solutions.

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1. 1. The presence of an enzyme system in plants catalyzing the formation of α-acetolactate from pyruvate has been demonstrated; the system in green gram (Phaseolus radiatus) has been partially purified and its characteristics have been studied.2. Free acetaldehyde is formed as a product of the reaction and so the reaction is mainly diverted towards the formation of acetoin. 3. The system requires thiamine pyrophosphate and a divalent metal ion (Mn2+ or Mg2+) for maximum activity. The optimum pH is around 6.0 and the optimum temperature is 60°. 4. The system is very labile in absence of pyruvate, Mn2+ and DPT. 5. The Km values for pyruvate, Mn2+, Mg2+ and DPT are 3·10−2 M. 5·10−5 M, 2·10−5 M, and e·10−6 M respectively. The activation energy is 3540 cal/mole. 6. The enzyme is strongly inhibited by p-chloromercuribenzoate and the inhibition can be reversed partially by 2-mercaptoethanol, BAL or cysteine. Heavy metals, such as Hg2+ and Ag+, are inhibitory but l-valine does not inhibit the reaction.

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QUITE OFTEN, metal ions profoundly affect the condensation of carbonyl compounds with primary amines to form Schiff bases as well as their subsequent reactions[I-4]. Condensation of benzaldehyde with o-phenylenediamine (opd) in glacial acetic acid[5] or in absolute alcohol[6] gives benzimidazole derivative, 1-benzyl-2-phenylbenzimidazole (bpbi). In this reaction, the Schiff base N,N'-dibenzylidene-o-phenylenedianfme (dbpd) has been postulated as an intermediate, which cyclises to give bpbi. It was found that the reaction of opd in presence of copperO1) perchlorate with benzaldehyde gave dbpd complex of copper(l) perchlorate instead of bpbi.

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Spectrophotometric and potentiometric investigations have been carried out on copper-monoethanolamine complexes. Job plots at 920, 760 and 620 mµ have indicated the formation of CuA++, CuA2/++ and CuA3 ++. The$$\bar n - pA$$ curves have been obtained by a slight modification of the method of corresponding solutions and by pH measurements. The$$\bar n$$ vs. pA curves obtained at different metal concentrations coincide indicating the formation of mononuclear complexes. Experiments conducted with 0·1. 0·2, 0·5 and 1·0 M monoethanolammonium ion indicate the formation of mononuclear hydroxy complexes above pH 6. The nature of E m vs pA curves is closely analogous to that of$$\bar n$$ vs. pA curves. Absorption spectra taken at pH 9·8 with different amounts of monoethanolamine has given evidence for the formation of (CuA3OH·A)+.$$\bar n - pA$$ curves have been analyzed and the values ofβ 1, 1,β 1, 2 andβ 1, 3 have been obtained. Curves showing the distribution of complexes and the absorption curves of the individual complexes (CuA++, CuA2/++, and CuA3/++) have been calculated.

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Ethylα-bromovinylacetate (VII) was condensed with the sodio derivative of ethyl piperonoylacetate (VIII) to give diethylα-vinyl-α′-piperonoylsuccinate (IX). The latter on reduction with lithium aluminium hydride furnished the triol (X), which underwent smooth cyclisation with 1% ethanolic hydrogen chloride to 2-(3′, -methylenedioxyphenyl)-hydroxymethyl-4-vinyltetrahydrofuran (XIa). The structure of XIa was established by Oppenauer oxidation to an aldehyde. Ozonolysis of XIa afforded samin (I).

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The partial purification of the enzyme hydrolysing FMN from extracts of greengram seeds (Phaseolus radiatus) is described. The procedures, which entailed precipitation of inert material by manganous sulfate and protamine sulfate treatment, fractional precipitation with alcohol and chromatography on CM-cellulose, afforded preparations whose specific activity was 200 times that of the initial crude extract. The preparation was comparatively specific for FMN. It also hydrolysed, to a much smaller extent, β-glycerophosphate, p-nitrophenyl phosphate and 5′-nucleotides. The differential effects of ions on the FMN and β-glycerophosphate hydrolysing activities are discussed.

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The partial purification of the enzyme hydrolysing FMN from extracts of greengram seeds (Phaseolus radiatus) is described. The procedures, which entailed precipitation of inert material by manganous sulfate and protamine sulfate treatment, fractional precipitation with alcohol and chromatography on CM-cellulose, afforded preparations whose specific activity was 200 times that of the initial crude extract. The preparation was comparatively specific for FMN. It also hydrolysed, to a much smaller extent, β-glycerophosphate, p-nitrophenyl phosphate and 5′-nucleotides. The differential effects of ions on the FMN and β-glycerophosphate hydrolysing activities are discussed.

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The structure, synthesis, and configuration of the lactone of tricycloekasantalic acid have been described. It has been shown that in the formation of this lactone (XII) from the acids (I) or (II) a rearrangement is involved.

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A detailed investigation of the natural frequencies and mode shapes of simply supported symmetric trapezoidal plates is undertaken in this paper. For numerical calculations, the relationship that exists between the eigenvalue problem of a polygonal simply supported plate and the eigenvalue problem of polygonal membrane of the same shape is utilized with advantage. The deflection surface is expressed in terms of a Fourier sine series in transformed coordinates and the Galerkin method is used. Results are presented in the form of tables and graphs. Several features like the crossing of frequency curves and the metamorphosis of some of the nodal patterns are observed. By a suitable interpretation of the modes of those symmetric trapezoidal plates which have the median as the nodal line, the results for some of the modes of unsymmetrical trapezoidal plates are also deduced.