2003

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Synchronized whistlers recorded at Varanasi
(Indian Academy of Sciences, 2003) Singh, Rajesh; Singh, Ashok K.
Some interesting events of synchronized whistlers recorded at low latitude station Varanasi during magnetic storm period of the year 1977 are presented. The dynamic spectrum analysis shows that the component whistlers are Eckersley whistlers having dispersion 10 s1/2 and 30 s1/2. An attempt has been made to explain the dynamic spectra using lightning discharge generated from magnetospheric sources.
Devitrification of rapidly quenched Al-Cu-Ti amorphous alloys
(Indian Academy of Sciences, 2003) Misra, D.K.; Tiwari, R.S.; Srivastava, O.N.
X-ray diffraction, transmission electron microscopy and differential scanning calorimetry were carried out to study the transformation from amorphous to icosahedral/crystalline phases in the rapidly quenched Al 50Cu45Ti5 and Al45Cu 45Ti10 alloys. In the present investigation, we have studied the formation and stability of amorphous phase in Al50Cu 45Ti5 and Al45Cu45Ti10 rapidly quenched alloys. The DSC curve shows a broad complex type of exothermic overlapping peaks (288-550°C) for Al50Cu45Ti 5 and a well defined peak around 373°C for Al45Cu 45Ti10 alloy. In the case of Al50Cu 45Ti5 alloy amorphous to icosahedral phase transformation has been observed after annealing at 280°C for 73 h. Large dendritic growth of icosahedral phase along with α-Al phase has been found. Annealing of Al50Cu45Ti5 alloy at 400°C for 8 h results in formation of Al3Ti type phase. Al45Cu 45Ti10 amorphous alloy is more stable in comparison to Al50Cu45Ti5 alloy and after annealing at 400°C for 8 h it also transforms to Al3Ti type phase. However, this alloy does not show amorphous to icosahedral phase transformation.
Biomimetic synthesis of superparamagnetic iron oxide particles in proteins
(Materials Research Society, 2003) Sinha, Arvind; Nayar, Suprabha; Murthy, G.V.S.; Joy, P.A.; Rao, V.; Ramachandrarao, P.
Matrix-mediated in situ synthesis of monodispersed magnetite and maghemite nanoparticles (2-16 nm) was carried out using the cavities present in gels of globular proteins such as egg white and bovine serum albumin. Under stringent conditions, spatial-charge-distribution-assisted molecular recognition of proteins for inorganic ions led to the site- and polymorph-specific synthesis of superparamagnetic iron oxide particles. A transformation from magnetite to maghemite as a nucleating phase could be observed by partially denaturing the egg white protein, signifying the delicate role of quaternary structure of proteins under different reaction conditions, in determining the size and shape of the polymorph.
Effect of furfuryl alcohol on the properties of hydrated cement mortar
(Materials Research Society, 2003) Singh, V.K.; Singh, R.K.; Khatri, S.D.
The effect of furfuryl alcohol addition to ordinary cement on its properties, such as heat of hydration, setting time, compressive strength, and tensile strength was studied by adding 0.5-3.0% by weight of cement. Hardness was tested using the Vickers indentation method. Fracture toughness of cementitious bond and bending strength were determined using the three-point bending system. Corrosion resistance of resulting products was tested against 0.1 and 1.0 N HCI and H2SO4 and seawater, respectively. Water absorption/open porosity and microstructure were also determined. It was observed that strength, hardness, toughness, and corrosion resistance increase up to 3.0% addition of furfuryl alcohol in ordinary Portland cement. Polymeric phase was interspersed in cement, causing a decrease in water absorption/open porosity, and its interaction with hydrating cement caused additional bond formation, leading to the increase in strength.
Tribological behaviour of conventional Al-Sn and equivalent Al-Pb alloys under lubrication
(Indian Academy of Sciences, 2003) Pathak, J.P.; Mohan, S.
Two compositions of conventional aluminium base alloys were selected and equal amounts of tin and lead as a soft phase were incorporated separately. Impeller mixing and chill casting technique were employed for the preparation of the alloys. Mechanical properties of as cast alloys were evaluated at room temperature. Frictional behaviour of the alloys was studied in detail under lubrication while creating different frictional states by imposing 5-60 kg of normal load on the bearing (bush) mating surface. It was found that aluminium tin and leaded aluminium alloys slightly differ in mechanical properties. Frictional states created during sliding against steel shaft (hardness 55-60 Rc) under oil lubrication were not much different. Leaded aluminium alloy bushes show marginally lower friction than the conventional ones.
Triggered emissions observed at Varanasi (India)
(Elsevier Ltd, 2003) Singh, R.P.; Patel, R.P.; Singh, D.K.
Whistler triggered emissions recorded at a low latitude station e.g. Varanasi are described. The study covers various aspects of these emissions including riser, riser followed by constant frequency emissions, hiss and oscillating tones. Analysis shows that the whistlers have propagated along paths with L-values lying between L = 1.9 and 2.4, suggesting that these whistlers are to be regarded as mid-latitude whistlers. These waves could have propagated along the geomagnetic field lines either in a ducted mode or in a pro-longitudinal mode. The measured intensity of the triggered emissions is either equal to or more than that of the source wave and also varies from one event to another. It is proposed that these emissions are generated through a process of resonant interaction of the whistler waves with energetic electrons. Parameters related to this interaction are computed for different values of L and wave amplitude. The proposed mechanism explains some aspects of the dynamic spectra. © 2003 Elsevier Science Ltd. All rights reserved.
Synthesis of nanosized and microporous precipitated hydroxyapatite in synthetic polymers and biopolymers
(American Ceramic Society, 2003) Sinha, Arvind; Nayar, Suprabha; Agrawal, Archana; Bhattacharyya, Debasish; Ramachandrarao, Patcha
In situ precipitation of microporous and nanosized hydroxyapatite particles (5-40 nm) has been conducted in poly(vinyl alcohol) and bovine serum albumin gels. The process, which is similar to biomineralization, is highly controlled with respect to microstructural features, such as size and shape, and to precipitation of hydroxyapatite phase having a calcium:phosphorus stoichiometric ratio of 1.67. Nanosized precipitated hydroxyapatite particles show remarkable thermal stability and do not decompose to other calcium phosphate phases, even at higher temperatures.
Preparation, characterization and performance of a silica gel bonded molecularly imprinted polymer for selective recognition and enrichment of β-lactam antibiotics
(2003) Prasad, Bhim Bali; Banerjee, Shouri
A silica gel-bound molecularly imprinted polymer to oxazolone(s) exclusively derived from certain cephalosporins (cefaclor) and penicillins (amoxycillins and ampicillins) was prepared using ethylacetate as a porogen. This was used as a packing material for solid phase extraction in column chromatography. The high selectivity and the quantitative sorption of oxazolone at pH 7.5 and a flow rate of 5.0 ml min-1 in a long (13.0 cm) and wide bore (1.4 cm internal diameter) column have led to efficient clean-up, selective enrichment, and indirect differential pulse adsorptive stripping voltammetric measurement of the β-lactams in the form of corresponding oxazolones either in a larger volume of dilute aqueous systems or in the pharmaceutical formulations, without complications of complex matrices, excipients or column deterioration. © 2003 Elsevier Science B.V. All rights reserved.
Statistical mechanics of thermal denaturation of DNA oligomers
(Indian Academy of Sciences, 2003) Singh, Navin; Singh, Yashwant
Double stranded DNA chain is known to have non-trivial elasticity. We study the effect of this elasticity on the denaturation profile of DNA oligomer by constraining one base pair at one end of the oligomer to remain in unstretched (or intact) state. The effect of this constraint on the denaturation profile of the oligomer has been calculated using the Peyrard-Bishop Hamiltonian. The denaturation profile is found to be very different from the free (i.e. without the constraint) oligomer. We have also examined how this constraint affects the denaturation profile of the oligomer having a segment of defect sites located at different parts of the chain.
Multiple cutaneous horns of the penis: A case report
(2003) Tewari, Mallika; Gupta, S.K.; Kumar, M.
Cutaneous horns of the penis are rare. Frequently they are unusual presentations of squamous cell carcinomas of the penis; therefore prompt surgical intervention is warranted. This is a report on a 70-year-old man with multiple cutaneous horns of the penis. The possible causes of cutaneous horns are reviewed.
Role of Seabuckthorn (Hippophae rhamnoides) in the maintenance of cardiovascular homeostasis following cold stress
(Natural Remedies Private Limited, 2003) Dubey, G.P.; Agrawal, A.; Dixit, S.P.
Objective: To study the beneficial role of Seabuckthorn (Hippophae rhamnoides) in the maintenance of cardiovascular homeostasis following cold stress. Materials and Methods: The effect of the alcoholic extract of Seabuckthorn in the daily oral dose of 500 mg was studied on various electrophysiological and neurochemical parameters following cold stress among the positive cold stress responders (human subjects) continuously for 3 months. Results: The average differences in cardiovascular responses like systolic and diastolic blood pressure, and pulse rate that were found to be raised following cold pressor test, minimized following three months oral administration of Seabuckthorn. Further, the psychophysiological parameters like occipito frontalis EMG and galvanic skin resistance also regulated under drug treatment. The serotonin and plasma cortisol levels were also modified following oral administration of Seabuckthorn. Conclusion: Seabuckthorn exhibited beneficial effects to reduce the cardiovascular reactivity following cold stress and thus it enhances the stress tolerance capacity as well as better adaptation towards stress.
Preparation, characterization and molecular electrical conductivity of an ion-pair complex and mixed-metallic coordination polymers derived from maleonitriledithiolate
(2003) Singh, Nanhai; Sinha, Rohit Kumar
An ion-pair complex [Cd(en)3]22+ [Ag4(mnt)4]4- and three mixed metallic coordination polymers MNi(mnt)2 [M = Pd(II), 2Ag(I) or Hg(II); mnt2- = maleonitriledithiolate] have been prepared and characterized using IR, UV-Visible and conductivity techniques. All of the complexes exhibit pressed pellet σrt ≃ 10-5 S cm-1 and show electrical behaviour of semiconductors over 303-393 K range. © 2002 Elsevier Science B.V. All rights reserved.
Brain tyrosine hydroxylase in the catfish Heteropneustes fossilis: Annual and circadian variations, and sex and regional differences in enzyme activity and some kinetic properties
(Academic Press Inc., 2003) Chaube, R.; Joy, K.P.
Dynamics of tyrosine hydroxylase (TH) was studied in various brain regions and pituitary in relation to annual/seasonal and circadian variations in either sex of the catfish Heteropneustes fossilis. α-Methylparatyrosine inhibited TH activity significantly in a time - (in vivo study) and concentration - (in vitro study) dependent manner. The inhibition was higher in resting phase than preparatory phase and in females than males (time-course study). The apparent kinetic constant of inhibition (Ki) varied both seasonally and regionally. The values were higher in resting phase and in the forebrain regions (telencephalon and hypothalamus) than medulla oblongata. No significant sex difference was noticed in the Ki values in the same season. TH activity showed significant annual/seasonal variations with telencephalon and hypothalamus showing higher activity than medulla oblongata. The females showed significantly higher enzyme activity than males with a distinct activity peak in June (prespawning phase). Such an activity peak was apparently absent in males. TH activity showed significant circadian/diurnal variations, the highest activity was noticed at 12h and the lowest at 24h. The apparent Michaelis-Menten constant (Km) values (hypothalamic TH) for substrate (L-tyrosine) and cofactor (DMPH4) showed seasonal variations with the highest values in the resting phase, decreasing through preparatory and prespawning phases, to the lowest values in spawning phase. Vmax was the lowest in the resting phase and highest in the spawning phase. TH activity was low in the pituitary and could be detected in pooled samples from March (preparatory phase) to July (spawning phase). Activity showed significant variations, which could be correlated with the gonadosomatic index. The results show that TH activity could be positively correlated with the annual reproductive cycle. The enzyme activity could be also correlated with seasonal, sex, and regional variations in the apparent Km and Vmax values suggesting apparent differences in the affinity of the enzyme towards substrate and cofactor. © 2002 Elsevier Science (USA). All rights reserved.
Distribution of larger foraminifera in the reef sediments of Akajima, Okinawa, Japan
(2003) Saraswati, Pratul Kumar; Shimoike, Kazuyuki; Iwao, Kenji; Mitra, Arijit
This paper examines the bathymetric distribution of larger foraminiferal species on the reef flat and reef slope of Akajima Island, located near Okinawa in the Ryukyu island arc of Japan. It also estimates the total skeletal carbonates contributed by larger foraminifera in the reef sediments of this island. Three distinct assemblages are recognized with increasing water-depths: (i) Marginopora vertebralis and Baculogypsina sphaerulata are confined to reef flat, occurring at a water depth of 1.5 m (ii) Peneroplis planatus and Neorotalia calcar occur within 30 m bathymetry followed down depth by (iii) Operculina ammonoides, Nummulites venosus, Alveolinella quoyi and Baculogypsinoides spinosus between 30 and 60 m. Cycloclypeus is the deepest dwelling genus, making its first appearance at 60 m. Larger foraminifera contribute about 5.8% of the sediments accumulated on reef flat and reef slope of Akajima, which is significantly higher than the global average. There is considerable variation in relative contributions by miliolids and rotaliids on reef flat and reef slope. On the reef flat, miliolids contribute 64% of the total skeletal carbonates produced by larger foraminifera, whereas on reef slope it contributes only about 5%.
Purification and biochemical characterization of a highly active cysteine protease ervatamin A from the latex of Ervatamia coronaria
(2003) Nallamsetty, Sreedevi; Kundu, Suman; Jagannadham, Medicherla V.
Ervatamia coronaria, a flowering plant (family Apocynaceae) indigenous to India, has medicinally important applications. A search for biochemical constituents of the latex of the plant yielded at least three thiol proteases with distinctly different properties. One of them, a highly active protease (ervatamin A), was purified to homogeneity by ion exchange and gel filtration chromatography. The enzyme exhibited high proteolytic activity toward natural substrates and amidolytic activity toward synthetic substrates. The pH and temperature optima for proteolytic activity were 8-8.5 and 50-55°C, respectively. Proteolytic activity of the enzyme was strongly inhibited by thiol-specific inhibitors. The estimated molecular mass of the enzyme was 27.6 kDa. The extinction coefficient (Ε1% 280) of the enzyme was estimated as 21.9, and the protein molecule consists of 8 tryptophan, 11 tyrosine and 7 cysteine residues. Isoelectric point of the purified enzyme was 8.37. Polyclonal antibodies raised against the pure enzyme gave a single precipitin line in Ouchterlony's double immunodiffusion and a typical color in ELISA. The N-terminal sequence of the enzyme showed conserved amino acid residues to other plant cysteine proteases. Ervatamin A shows high activity in relation to the other thiol proteases isolated from the same source.
Influence of thermomechanical treatments on the microstructure and mechanical properties of HSLA-100 steel plates
(Minerals, Metals and Materials Society, 2003) Dhua, S.K.; Mukerjee, D.; Sarma, D.S.
The influence of thermomechanical treatment (TMT), i.e., controlled rolling and direct quenching, as a function of rolling temperature and deformation on the microstructure and mechanical properties of HSLA-100 steel have been studied. The optical microstructure of the direct quenched (DQ) and tempered steel rolled at lower temperatures (800°C and 900°C) showed elongated and deformed grains, whereas complete equiaxed grains were visible after rolling at 1000°C. The transmission electron microscope (TEM) microstructure of the 800°C rolled DQ steel showed shorter, irregular and closer martensite laths with extremely fine Cu and Nb(C,N) precipitates after tempering at 450°C. The precipitates coarsened somewhat after tempering at 650°C; the degree of coarsening was, however, less compared to that of the reheat-quenched (RQ) and tempered steel, indicating that the DQ steel was slightly more resistant to tempering. Similar to the RQ steel, at a 450°C tempering condition, the DQ steel exhibited peak strength with extremely poor impact toughness. After tempering at 650°C, the toughness of the DQ steel improved significantly, but at the expense of its strength. In general, the strength of the DQ and tempered steel was good and comparable to that of the RQ and tempered steel, although, its impact toughness was marginally less than the latter. The optimum combination of strength and toughness in the DQ steels was achieved after 900°C rolling with 50 pct deformation, followed by direct quenching and tempering at 650°C (yield strength (YS) = 903 MPa, ultimate tensile strength (UTS) = 928 MPa, and Charpy V-notch (CVN) strength = 143 J at -85°C).
Melanotic neuroectodermal tumour of infancy: A rare maxillary alveolar tumour
(Springer Verlag, 2003) Jain, P.; Saxena, S.; Aryya, N.C.
Melanotic neuroectodermal tumour of infancy is a rare, but usually benign, pigmented neoplasm occurring in the first few months of life. The most frequent site is anterior maxillary alveolar ridge. It should be differentiated from other head and neck neoplasms of infants. Computed tomography and fine-needle aspiration cytology are the choice of investigations while two-cell population of neuroblasts and melanocytes on histology confirms the diagnosis. Treatment is early conservative surgical excision with long-term follow-up to detect recurrence and malignant transformation. A classical case of a 7-month-old infant is described with a brief review of the literature.
Antispermatogenic and antifertility effects of 20,25-diazacholesterol dihydrochloride in mice
(2003) Singh, Shio K.; Chakravarty, Sumana
The effect of intraperitoneal administration for 28 days of 10, 20, and 30 mg/kg body weight per day of 20,25-diazacholesterol dihydrochloride (SC 12937), a hypocholesterolemic agent, on the testis of Parkes (P) strain mice was investigated. Histologically, testes in mice treated with 10 or 20 mg/kg body weight of SC 12937 showed non-uniform degenerative changes in the seminiferous tubules as both affected and normal tubules were observed in the same section; the affected tubules showed intraepithelial vacuolation, occurrence of giant cells, exfoliation of germ cells, and marginal condensation of chromatin in round spermatids. In both dosage groups, only 11-12% of the seminiferous tubules were affected, and no significant differences were found in the frequency of affected tubules between the two groups. By contrast, testes in mice treated with 30 mg/kg body weight of the drug exhibited a degenerated appearance of germ cells in all seminiferous tubules. The treatment also had adverse effects on motility, viability, morphology, and number of spermatozoa in the cauda epididymidis, and on fertility. Even 56 days after drug withdrawal, the above parameters remained markedly affected. Our results thus suggest that SC 12937 treatment causes antispermatogenic and antifertility effects in P mice and that the effects are not reversible up to 56 days after drug withdrawal. This compound may prove useful in the control of rodent populations. © 2002 Elsevier Science Inc. All rights reserved.
Setaria cervi: In vitro released collagenases and their inhibition by Wuchereria bancrofti infected sera
(2003) Singh, R.N.; Rathaur, S.
In vitro released products of adult Setaria cervi females, microfilariae and extracts showed considerable amounts of collagenase activity. On the basis of per mg protein released in vitro, the products of both microfilariae and adult females exhibited comparable activity but this was much higher than that of extract of microfilariae and adult females. Two collagenase enzymes with molecular masses of 50 kDa and 70 kDa were separated using DEAE-sepharose CL6B and Sephadex G-100 column chromatography. The 50 kDa and 70 kDa collagenase exhibited pH optima of 5.2 and 7.0, respectivly. Considering specific activity, the 50 kDa enzyme was found to contribute about ten times more collagenase activity as compared to the 70 kDa enzyme. An inhibition study revealed obvious differences between them. Thiol group inhibitors such as N-ethylmaleimide and leupeptin inhibited the 50 kDa enzyme but this was strongly activated by dithiothreitol, a thiol group stabilizer. Alternatively, the 70 kDa enzyme showed a sensitivity to a metal chelator and a serine group inhibitor indicating its metalloserine protease nature. The antifilarial drug diethylcarbamazine did not demonstrate any inhibition under in vitro conditions. Both enzymes were significantly inhibited by antibody IgG separated from Wuchereria bancrofti infected human sera, showing a possible immunoprotective role.
In vitro clonal propagation through bud culture of Hemidesmus indicus (L) R Br: An important medicinal herb
(Society for Plant Biochemistry and Biotechnology, 2003) Saha, Soma; Mukhopadhyay, Madhumita J.; Mukhopadhyay, Sandip
The present study involves in vitro propagation of Hemidesmus indicus (L) R Br through bud multiplication and subsequent plant regeneration.The buds multiplied to produce numerous shoots at variable rates in presence of α-naphthaleneacetic acid (NAA) and 6-benzylaminopurine (BAP) as well as NAA and kinetin. The best response in bud multiplication was obtained in Murashige and Skoog's (MS) basal medium supplemented with 0.1 mg I-1 NAA and 2.0 mg I-1 BAP (7-8 shoots per explant) and the bud break time was only 4 days after inoculation. The multiplication rate was low when the buds were cultured in NAA and kinetin media and the shootlets regenerated were very thin, weak and elongated. The shoots regenerated were further cultured on MS and half strength MS basal media with variable levels of indole-3-butyric acid (IBA) for initiation of roots. Culture of shootlets for 3-4 weeks in one half strength of MS medium followed by culturing in the same medium with 1.5 mg I-1 IBA induced highest production of roots (3-5 roots per shoot) within 2 weeks. Chromosome number stability with no detectable structural changes was observed in the regenerates. The rooted plants were successfully established in the soil with 85% survival rate.

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