scispace - formally typeset
Search or ask a question

Showing papers by "University of Madras published in 1984"


Journal ArticleDOI
TL;DR: In this article, a simple turbidity measurement made use of a spectrophotofluorometer is described for the study of the interpolymer adduct formation in the presence of Cu(II) ions.
Abstract: Interpolymer adduct formation between poly(N-vinylpyrrolidone) (PVP) and poly(methacrylic acid) (PMAA) is mainly due to hydrogen bonding. It is found that the interpolymer adduct formation is enhanced in the presence of Cu(II). A simple turbidity measurement making use of a spectrophotofluorometer is described for the study of the interpolymer adduct formation. Enhanced adduct formation in the presence of Cu(II) is described by the empirical relation d[PAd]/D[PVP] = k × 104α[Cu(II)]α, where PAd represents the interpolymer adduct and α and k are constants. Similar results have been obtained in the case of interpolymer adduct formation between poly(acrylic acid) (PAA) and PVP. In the above expression α signifies the influence of chelation on Cu(II)–PAA/PMAA–PVP-type complex formation and k is the extent of PVP–PAA/PMAA interaction. The enhancement of adduct formation in the presence of Cu(II) is more in PAA than in PMAA. Turbidity and viscosity measurements further indicate that the influence of Cu(II) on interpolymer adduct formation between PVP and PMAA or PAA is more in the case of PAA than PMAA, as PAA is a better chelating ligand. But the extent of adduct formation is more in the case of PMAA in the absence of Cu(II) ions due to hydrophobic interactions exerted by methyl groups.

31 citations


Journal ArticleDOI
TL;DR: In this paper, a carbozole derivative of 2,3-dimethylindole is converted into N-benzoyl-2,3dibromo methylindole, the latter upon treatment withsodium iodide in DMF in the presence of a suitable dienophile.

28 citations


Journal ArticleDOI
TL;DR: Spectrofluorometric quantitation of a lignan lactone, diphyllin, and its glycosides cleistanthin A and Cleistanthin B, the active principles of the poisonous plant Cleistanthus collinus, is reported for the first time.
Abstract: Spectrofluorometrlc quantltatlon of a Ilgnan lactone, diphyllin, and its glycosides cleistanthin A and cleistanthin B, the active principles of the poisonous plant Ctelstanthus collinus, is reported for the first time. Thin layer chromatographic resolution of the components precedes the fluorometric measurements. The method is highly reproducible and sensitive to 0.1 pg/mL for diphyllln and to 1 pg/mL for cleistanthins A and B in ethanol. The technique is employed for the assay of several biospeclmens of forensic and clinical importance.

25 citations


Journal ArticleDOI
TL;DR: Evidence is presented for the first time to show a possible correlation between acclimation temperature and phase-transition temperature of hypothalamic phospholipid membrane and a direct physico-chemical basis is suggested for the thermoregulatory process of hypothalamus leading to a better understanding of the authors' knowledge on the origin of thermoreGulation.

22 citations


Journal ArticleDOI
TL;DR: In this article, the synthesis and rearrangement of optically active etynyl and vinyl carbinols 3 and 4 are reported, and the rearrangements are found to be concerted when carried out with KH-THF and non-concerted with KOH-methanol.

22 citations


Journal ArticleDOI
TL;DR: In this paper, the Vegard's law has been applied to the magnesium ferrite-aluminate series MgAlxFe2-xO4 (x=0.2, 0.4 and 0.7).
Abstract: The magnesium ferrite-aluminate series MgAlxFe2-xO4 (x=0.2, 0.4 and 0.7) has been synthesised, the lattice constants determined and the applicability of Vegard's law has been tested. The Mossbauer spectra have been recorded from 77K to a temperature well above the Neel point. The Neel temperature decreases linearly with the increase of aluminium concentration. The centre shifts are found to be independent of the aluminium concentration. The Mossbauer spectra have also been recorded at 4.2K in an external magnetic field of 4.2 T applied parallel to the direction of the gamma rays. For x=0.2 the canting of Fe spins is observed only on the A site and the B-site Fe spins have a collinear spin structure. This is the only spinel ferrite where the spin canting has been clearly observed on the A site alone when the B-site Fe spins have a collinear spin structure. For x=0.4 and x=0.7 both A- and B-site Fe ions have a noncollinear spin structure. The distribution of hyperfine fields at the A and B sites has been analysed in terms of supertransferred hyperfine fields from neighbouring ions.

18 citations


Journal ArticleDOI
TL;DR: Though the time taken for vitellogenesis and commencement of spawning were constant for the study period, the duration of retention of the juveniles in the brood varied with the onset of monsoon.
Abstract: The reproductive cycle of the field crab Paratelphusa hydrodromous (Herbst) was determined by direct field observations as well as by calculating the percentage of ovigerous females in a Madras population for a period of three years. The females breed annually in a single spawning. These observations, corroborated by histological studies on the nature of the ovary, indicate that gametogenic activity starts in December and vitellogenesis is completed during January-May. Spawning commences in the last week of June or first week of July with the release of brood in the month of September (1979), October (1978) or November (1980) during northeast monsoon. The smallest female crab showing spawning had a carapace width of 3.1 cm and the largest spawning crabs measured 5.5 mm. The mean number of eggs spawned in the smallest crab was 247 and that in the largest crab was 417. Mean incubation was 41 ± 12.388 days. Vitellogenesis and spawning occurred at peak temperature conditions. Though the time taken for vitellogenesis and commencement of spawning were constant for the study period, the duration of retention of the juveniles in the brood varied with the onset of monsoon.

17 citations


Journal ArticleDOI
TL;DR: A colorimetric assay procedure has been successfully developed for the analysis of cyclopiazonic acid present in infected rice, corn, and wheat.
Abstract: A method has been developed for quantitative determination of cyclopiazonic acid, a mycotoxin produced by a common food contaminant, Penicillium cyclopium. The organism was grown successively in synthetic minimal medium, rice, corn, and wheat for 15 days. The toxin was extracted with chloroform followed by separation by thin layer chromatography. A colorimetric assay procedure has been successfully developed for the analysis of cyclopiazonic acid present in infected rice, corn, and wheat. The sensitivity of the method was tested by using recovery experiments.

16 citations


Journal ArticleDOI
TL;DR: The origin, ultrastructure and histochemical properties of the egg membranes in the South Indian anostracan, Streptocephalus dichotomus have been studied and scanning electron microscopic observations on the egg surface reveal the characteristic ridges on theegg surface with pores.
Abstract: The origin, ultrastructure and histochemical properties of the egg membranes in the South Indian anostracan, Streptocephalus dichotomus have been studied. The egg morphology and the ultrastructure of the tertiary membrane of this phyllopod crustacean have been examined both by scanning and transmission electron microscopy. Scanning electron microscopic observations on the egg surface reveal the characteristic ridges on the egg surface with pores. Similarly, the tertiary egg shell of S. dichotomus consists of two distinct layers, an outer cortex and an inner alveolar layer. There are specific differences in the structure and in the relationship of one layer to the other. The alveolar layer is characterised by large lipid droplets and an alveolar mesh. These two layers termed as tertiary layers are secreted by maternal shell glands. The outer tertiary egg layers are phenolically tanned, the precursor materials for tanning being derived from shell gland secretions.

15 citations


Journal ArticleDOI
TL;DR: A black gram (Vigna mungo) trypsin inhibitor (BGTI) was purified to homogeneity by ammonium sulphate precipitation, DEAE-cellulose chromatography and affinity chromatography, finding it to be an uncompetitive inhibitor.
Abstract: A black gram (Vigna mungo) trypsin inhibitor (BGTI) was purified to homogeneity by ammonium sulphate precipitation, DEAE-cellulose chromatography and affinity chromatography. The homogeneity of the inhibitor was identified by polyacrylamide gel electrophoresis (PAGE), SDS–PAGE, immunodiffusion and immunoelectrophoresis. The isoelectric point of BGTI was 8.32. The molecular weight of the BGTI was found to be about 12500 by both gel filtration and SDS–PAGE. One mole of the BGTI was found to contain 75 amino acid residues, and it was identified as a glycoprotein, comprising about 18.2% carbohydrate. The BGTI was an uncompetitive inhibitor, stable in the pH range 2–10 and in the temperature range 30–80°C for 30 min.

12 citations


Journal ArticleDOI
TL;DR: In this article, the authors investigated the effect of the bulky and polar aryloxy side chain on the steric effect of polymers obtained by free-radical and ionic routes.
Abstract: By exposure to ultraviolet and gamma radiation and by the usual methods of thermal polymerization, the stereospecific polymerization of methyl aryloxymethacrylates was carried out at different temperatures in several solvents. Triad tacticity values of the polymers obtained by free-radical and ionic routes were computed from nuclear magnetic resonance spectral data. Results of this investigation support our earlier observation that, under the conditions used, heterotactic content is the maximum in most of these polymers, thereby justifying the high steric effect of the bulky and polar aryloxy side chain which offers equal isotactic and syndiotactic placements.

Journal ArticleDOI
TL;DR: In this article, the effect of colour component in the electromagnetic current on the high p T region (p T ⪆ 5 GeV ) was studied from the point of view of its implications on the gauge integer charge quark model.

Journal ArticleDOI
TL;DR: In this paper, the electronic bandstructures of rare earth metal Praseodymium (Pr) have been calculated for a wide range of static pressures using RAPW method and the density of states and Fermi surface cross sections on the principal planes corresponding to various pressures are obtained.
Abstract: The electronic bandstructures of rare earth metal Praseodymium (Pr) have been calculated for a wide range of static pressures using RAPW method. The density of states and Fermi surface cross sections on the principal planes corresponding to various pressures are obtained. It is seen that, there is, 4f shell breakdown in Pr under pressure and formation of 4f bands. The calculation of the superconducting transition temperaturesT c corresponding to various pressures shows that Pr may become a high pressure superconductor like Cerium eventhough it is not observed experimentally to be a superconductor because of its magnetic character at normal pressure.

Journal ArticleDOI
TL;DR: Clearance rates of dyes injected into the hemocoel of the mud crab revealed several patterns of clearance and retention associated with physico-chemical and biological variables, important for understanding the molecular basis of recognition in crustaceans.
Abstract: Clearance rates of dyes injected into the hemocoel of the mud crab, Scyllaserrata, revealed several patterns of clearance and retention associated with physico-chemical and biological variables. Clearance rates remained constant: 1) when the molar concentrations of the injected dyes were equal, 2) after repeated injections of dyes and 3) after serum opsonization. Rates increased: 1) with higher molecular weight irrespective of charge, 2) at higher dye concentration and 3) at night concomitant with an increase in the hemocyte population. In contrast, clearance rates decreased with increasing crab size. Dye cleared from the hemolymph accumulated in the gills but not in the hepatopancreas, antennary glands nor gut. The retention of dyes in the gills increased with higher molecular weights. Granular hemocytes accumulated in the gill rachis and lamellae of dye treated but not in gills of normal and saline injected crabs. A role for hemocytes in molecular weight and concentration dependent clearance of dyes is suggested. Our findings are important for understanding the molecular basis of recognition in crustaceans.

Journal ArticleDOI
TL;DR: Electrophoretic data concerning the detection of different esterase species indicate the pre-dominant occurrence of carboxylesterase both in the ovary and hepatopancreas, which is suggested to play a role in the translocation of lipid from the storage tissue to the site of utilization.

Journal ArticleDOI
TL;DR: Methylα-aryloxymethylacrylates as discussed by the authors have been found to rearrange to furnish the methylenecoumarins when refluxed in methylene chloride in the presence of anhydrous AlCl 3.

Journal ArticleDOI
TL;DR: The study showed that the CMI appeared earlier than the humoral response which might be useful in the early detection of the disease.
Abstract: Humoral and cell-mediated immune responses (CMI) to leptospirosis were studied in different groups of human patients. These included clinically suspected cases of leptospirosis, patients with jaundice (HBsAg negative), cases of pyrexia of unknown origin (PUC) (Widal and blood culture negative for typhoid) and healthy blood donors. Humoral immune response was evaluated with nine live strains representing different serogroups of leptospires and CMI with lysates of four strains. The study showed that the CMI appeared earlier than the humoral response which might be useful in the early detection of the disease. As in the humoral immune response, cross reactions to different leptospires were also seen in CMI response.

Journal ArticleDOI
TL;DR: The study reveals a direct, specific influence of thyroxine on different testicular enzymes of the pyruvate/malate cycle.

Journal ArticleDOI
TL;DR: In this article, it was found that the hardness of the tabular crystals is of the same order of magnitude as those of natural crystals of gypsum, whereas interpenetration twinned crystals show a remarkable increase in hardness.
Abstract: In a single test tube system, gypsum crystals grown in alcoholic gel comprise of interpenetration twinned crystals at the interface towards the gel, whereas untwinned tabular crystals are observed at greater depths inside the gel. By indentation of the crystals with a microhardness tool and recording the indentation impressions by means of a scanning electron microscope (SEM) and a transmission electron microscope (TEM) it is found that the hardness of the tabular crystals is of the same order of magnitude as those of natural crystals of gypsum, whereas interpenetration twinned crystals show a remarkable increase in hardness. On studying the morphology of cleavage faces and on carrying out energy dispersive X-ray analysis (EDXA), it is concluded that the increase in hardness of interpenetration twinned crystals with respect to tabular and natural crystals may be due to the role of the inclusion of gel particles during the growth. The implications are discussed. Im Reagenzglas wachsen Gipskristalle in alkoholhaltiger Gellosung nahe der Grenzflache zum Gel in Form von sich gegenseitig durchdringender Zwillinge. Im Inneren der Gellosung werden unverzwillingte Kristallblattchen beobachtet. Durch Vermessung von Mikroharteeindrucken mit Hilfe der REM- und TEM-Technik zeigt sich, das die Harte der unverzwillingten Blattchen etwa mit der von naturlich gewachsenem Gips ubereinstimmt. Im Gegensatz dazu weisen die Zwillingskristalle eine grosere Harte auf. Aus der Morphologie von Spaltflachen und aus EDXA-Untersuchungen kann geschlossen werden, das die grosere Harte der Zwillingskristalle auf Geleinschlusse wahrend des Wachstums zuruckzufuhren ist. Die Ergebnisse werden diskutiert.

Journal ArticleDOI
01 Jun 1984
TL;DR: These leafhopper and planthopper transmitted viruses are discussed in this paper and are known to be active vectors of about 25 viruses infecting cereal crops.
Abstract: Leafhoppers in the familyCicadellidae and planthoppers in the familyDelphacidae are known to be active vectors of about 25 viruses infecting cereal crops. These leafhopper and planthopper transmitted viruses are discussed in this paper.


Journal ArticleDOI
01 Oct 1984
TL;DR: BothRhinocoris marginatus andCatamiarus brevipennis perform a sequential pattern of mating.
Abstract: BothRhinocoris marginatus andCatamiarus brevipennis perform a sequential pattern of mating. The order of mating events is as follows—arousal—approach—preovulatory riding—embracing—extension of genitalia and connection achievement and postcopulatory acts such as grooming and ejection of spermatophore capsule by the female.

Journal ArticleDOI
TL;DR: In this article, a charge transfer complex system of N, N -dimethylaniline-p -toluene sulphonyl chloride in acetonitrile medium at 50°C is reported.

Journal ArticleDOI
TL;DR: In this article, two categories of singularly normal estimators are proposed for (b 1,…,bq, b0) and several additional limit theorems based on estimated error residuals are proved.
Abstract: LetX(t) be a linear autoregressively generated explosive time series, with autoregressive coefficientsb 1,…,bq, and a constant termb 0, and an error term\(\bar \varepsilon \left( t \right) = a_0 \varepsilon \left( t \right) + a_1 \varepsilon \left( {t - 1} \right) + \cdots + a_l \varepsilon \left( {t - l} \right)\); a0=1. Where e(t),t≧1 are independent, Ee(t)=0, and Ee 2(t)=σ2 is positive and finite. In this paper two categories of\(\sqrt N \)-consisent and asymptotically singularly normal estimators are proposed for (b 1,…,bq, b0) thus settling an open problem since the publication of the paper (Venkataraman [5]). Based on these estimators several additional limit theorems based on estimated error residuals are proved. The parameter-free limit theorems of Spectral and Quenouille types of this paper serve as asymptotic goodness of fit tests for the model generatingX(t).

Journal ArticleDOI
TL;DR: In this article, methylmethacrylate and styrene were polymerized with Co(acac)3-AlEt2 Br catalyst system in benzene at 40°C.
Abstract: Methylmethacrylate and styrene were polymerized with Co(acac)3-AlEt2 Br catalyst system in benzene at 40°C. Rate of polymerization is linear to monomer concentrations. Maximum percent conversion of polymer was obtained when Al/Co⩾2 with styrene and Al/Co⩾3 with methylmethacrylate. With increase in aging time catalytic activity decreases. Activation energy was found to be 60 KJ mol−1. with styrene and 40 KJ mol−1. with methylmethacrylate.

Journal ArticleDOI
TL;DR: The withdrawal of thyroxine from hyperthyroid animals returned the epididymal lipid profiles to normal levels, indicating that the effects of thyoxine in the epidIDymis are temporary and reversible following Thyroxine withdrawal.

Journal ArticleDOI
TL;DR: In this article, the electronic band structures of fcc actinium (Ac) have been calculated for a wide range of pressures by reducing the unit-cell volume from $1.0{V}_{0} to $0.5{V]_{0]$ with use of the relativistic augmented-plane-wave method.
Abstract: The electronic band structures of fcc actinium (Ac) have been calculated for a wide range of pressures by reducing the unit-cell volume from $1.0{V}_{0}$ to $0.5{V}_{0}$ with use of the relativistic augmented-plane-wave method. The density of states and Fermi-surface cross sections corresponding to various volumes are obtained. Calculations for the band-structure-related quantities such as electron-phonon mass enhancement factor $\ensuremath{\lambda}$, superconducting transition temperature ${T}_{c}$, and resistivity $\ensuremath{\rho}$ corresponding to different volumes are performed. It is seen that ${T}_{c}$ increases with pressure, i.e., with decreasing volume. A new empirical relation for the volume dependence of ${T}_{c}$ is proposed and its validity is checked using the ${T}_{c}$ values obtained from the above band-structure results. The resistivity $\ensuremath{\rho}$ first increases with increasing pressure (i.e., with decreasing volume) and then decreases for higher pressures (i.e., for smaller volumes).

Journal ArticleDOI
TL;DR: Protein clearance was similar to dye clearance in several respects: 1) clearance rate increased with higher a) molecular weight and concentration and b) at night and 2) decreased with crab size, while HRP clearance rate was significantly increased after repeated injections of HRP but not saline and Hb clearance was not enhanced.
Abstract: The Defense reactions of Scylla serrata have been investigated by challenging crabs with two metalloproteins, horse radish peroxidase (HRP:M.W. 40,000) and hemoglobin (Hb:64,000). The defense response analyzed include 1) recognition of foreign proteins; 2) clearance from the haemocoel; 3) accumulation in tissues and 4) externalization. Protein clearance was similar to dye clearance in several respects: 1) clearance rate increased with higher a) molecular weight and concentration and b) at night and 2) decreased with crab size. HRP clearance rate was significantly increased after repeated injections of HRP but not saline. Clearance was not enhanced after repeated injections of Hb. About 70% of HRP accumulates in gills within 2 hours after injection, when there were no signs of HRP accumulation in the hepatopancreas. But about the same percent of injected Hb accumulated in both gills and hepatopancreas after 2 hours of injection. When 300 ug HRP declined in gills after 8 hour, similar amounts of HRP accumulated in the hepatopancreas. Moreover when 325 ug of Hb was lost from gills after 4 hours, the hepatopancreas accumulated about 300 ug, suggesting that foreign proteins may undergo antigenic alteration in the gills prior to mobilization to the hepatopancreas. There is no evidence of degradation of proteins in gills. When HRP and Hb level declined in the hepatopancreas, the levels of these proteins increased in gut contents indicating externalization of injected proteins via gut.

Journal ArticleDOI
TL;DR: The title compound has been synthesised via an alkylation, Wittig-Horner reaction sequence, and addition of several active methylene substrates with compound 1 has been carried out as mentioned in this paper.

Journal ArticleDOI
TL;DR: In this article, it was conjectured that the impurities preferred dislocation sites and that the trapped impurities become trapped in the interior of the crystal has been ascertained from the Laue X-ray transmission diffraction patterns.
Abstract: IAthium carbonate (Li2CO3) single crystals were grown by the zone melting technique [1] in CO2 atmosphere, doping with 1% K2CO 3 by weight. The etch pits on undoped crystal cleavages etched in 2% citric acid were triangular in shape with well defined sides, whereas the doped crystal cleavages revealed triangular pits which were anomalous in nature. When the trapped impurities were in bulk the etch pits revealed irregular contours, while in traces, pits showed grooves extending from the bottom point of the pit. On observing the etch figures in a scanning electron microscope, as well as from the etching experiments, it was conjectured that the impurities preferred dislocation sites. That the impurities become trapped in the interior of the crystal has been ascertained from the Laue X-ray transmission diffraction patterns. Much useful information can be obtained from the studies on different types of etch pits and their density regarding the nature of defects, impurity content and the history of growth of crystals. Pate1 and co-workers [2, 3] have shown that the te.rracing nature of etch pits are found due to the precipitation of impurities along the dislocation lines. It is quite probable that the fission fragment lying along the dislocation line may deviate the geometrical shape of the etch pit due to the preferential etching along the fission track giving rise to a groove or a wing shape to the etch pits. The anomalous nature of the etch pits formed due to the dissolution of the fission fragments present in the body of the crystal has been reported by Fleischer