Evaluation of Shungit -A Non-Petro Performance Filler in Tyre Compounds and Studies with Silica filler

( A. Chakravarty ),( S. N. Chakravarty ) 한국고무학회 2007 고무기술 Vol.8 No.2

Shungit are natural composite materials having unusual structure, consist of uniformly distributed highly dispersed crystalline silicate particles in amorphous carbon matrix. It`s main component is fullerene like Shungit carbon (upto 80%). Studies with Shungit, a non petro based performance carbon filler, in additional quantity to Carbon black in typical automotive tyre carcass, bead & apex and tread compounds as well as replacement of silica filler have been carried out and reported here. Rheological / Rheometric studies, Physico-mechanical properties determination, Dynamic Mechanical analysis & Rubber Process Analyzer studies were carried out with different compounds. Compound mixing was carried out in Brabender Plasticoder. Technological properties of rubber compound with Shungit were considerably improved with respect to Mooney viscosity and time of premature vulcanization start (Scorch Safety). DMA analysis shows lower tan delta value with Shungit containing compound. RPA studies also indicate lower heat development and tan delta. Results indicate that Shungit can replace, fully or partly, Silica in tyre tread compounds containing Carbon black.

Efficient keV X-ray Generation from Irradiation of in-situ Produced Silver Clusters by Ti:sapphire Laser Pulses

U. Chakravarty,P. A. Naik,S. R. Kumbhare,P. D. Gupta 한국광학회 2009 Current Optics and Photonics Vol.13 No.1

An experimental study of energy absorption and x-ray emission from ultrashort laser pulse irradiation of in-situ produced solid clusters has been performed. Silver clusters produced by a 30 mJ, 300 ps laser pulse were irradiated up to an intensity of 3×1017 W/cm2 by a 70 mJ, 45 fs compressed laser pulse from the same Ti:sapphire laser. Absorption of the laser light exceeding 70% was observed, resulting in an x-ray yield (>1 keV) of ~60 μJ/ pulse. This may constitute a much simpler means of intense x-ray generation using ultrashort laser pulses as compared to the irradiation of structured / pre-deposited cluster targets, and it offers higher x-ray conversion efficiency than that from gas clusters and planar solid targets.

Effect of oxygen partial pressure and annealing on nanocrystalline p-type ZnO:Sb thin films

K. Samanta,A.K. Arora,S. Hussain,S. Chakravarty,R.S. Katiyar 한국물리학회 2012 Current Applied Physics Vol.12 No.5

We have investigated the effect of oxygen partial pressure and annealing on nanocrystalline p-type Sb-doped ZnO thin films, grown by pulsed laser deposition, with hole concentration of 6.5 ×1018/cm3and mobility of 53 cm2/V-s. Uses of higher working pressure or annealing are found to reduce carrier concentration. A strong correlation is observed between carrier concentration and the violet (3.02 eV)emission related to free Zn-vacancy; stronger the violet emission, smaller the carrier concentration. In contrast to earlier suggestion of using higher oxygen pressure for obtaining p-type conductivity, the present results show a deterioration of the quality of film. We have investigated the effect of oxygen partial pressure and annealing on nanocrystalline p-type Sb-doped ZnO thin films, grown by pulsed laser deposition, with hole concentration of 6.5 ×1018/cm3and mobility of 53 cm2/V-s. Uses of higher working pressure or annealing are found to reduce carrier concentration. A strong correlation is observed between carrier concentration and the violet (3.02 eV)emission related to free Zn-vacancy; stronger the violet emission, smaller the carrier concentration. In contrast to earlier suggestion of using higher oxygen pressure for obtaining p-type conductivity, the present results show a deterioration of the quality of film.

Genetic Persistency of First Lactation Milk Yield Estimated Using Random Regression Model for Indian Murrah Buffaloes

Geetha, E.,Chakravarty, A.K.,Vinaya Kumar, K. Asian Australasian Association of Animal Productio 2006 Animal Bioscience Vol.19 No.12

A random regression model was applied for the first time for the analysis of test day records and to study the genetic persistency of first lactation milk yield of Indian Murrah buffaloes. Wilmink's Function was chosen to describe the shape of lactation curves. Heritabilities of test day milk yield varied from 0.33 to 0.58 in different test days. The highest heritability was found in the initial test day ($5^{th}$ day) milk yield. Genetic correlations among test day milk yields were higher in the initial test day milk yield and decreased when the test day interval was increased. The magnitude of genetic correlations between test day and 305 day milk yield varied from 0.25 to 0.99. The genetic persistencies of first lactation milk yield were estimated based on daily breeding values using two methods. $P_1$ is the genetic persistency estimated as a summation of the deviation of estimated daily breeding value on days to attain peak yield from each day after days to attain peak yield to different lactation days. $P_2$ is the genetic persistency estimated as the additional genetic yield (gained or lost) from days to attain peak yield to estimated breeding value on different lactation days relative to an average buffalo having the same yield on days to attain peak yield. The mean genetic persistency on 90, 120, 180, 240, 278 and 305 days in milk was estimated as -4.23, -21.67, -101.67, -229.57, -330.06 and -388.64, respectively by $P_1$, whereas by $P_2$ on same days in milk were estimated as -3.96 (-0.32 kg), -23.94 (-0.87 kg), -112.81 (-1.96 kg), -245.83 (-2.81 kg), -350.04 (-3.28 kg) and -407.58 (-3.40 kg) respectively. Higher magnitude of rank correlations indicated that the ranking of buffaloes based on their genetic persistency in both methods were similar for evaluation of genetic persistency of buffaloes. Based on the estimated range of genetic persistency three types of genetic persistency were identified. Genetic correlations among genetic persistency in different days in milk and between genetic persistencies on the same day in milk were very high. The genetic correlations between genetic persistency for different days in milk and estimated breeding value for 305 DIM was increased from 90 DIM to 180 DIM, and highest around 240 DIM which indicates a minimum of 240 days as an optimum first lactation length might be required for genetic evaluation of Indian Murrah buffaloes.

Influence of Temperature and Humidity on Pregnancy Rate of Murrah Buffaloes under Subtropical Climate

Soumya Dash,A. K. Chakravarty,V. Sah,V. Jamuna,R. Behera,N. Kashyap,B. Deshmukh 아세아·태평양축산학회 2015 Animal Bioscience Vol.28 No.7

Heat stress has adverse effects on fertility of dairy animals. Decline in fertility is linearly associated with an increase in combination of both temperature and humidity. The purpose of this study was to investigate the relationship between temperature humidity index (THI) and the pregnancy rate of Murrah buffaloes in a subtropical climate. The effects of genetic and non-genetic factors viz., sire, parity, period of calving and age group at first calving were found non-significant on pregnancy rate. The effect of THI was found significant (p<0.001) on pregnancy rate of Murrah buffaloes calved for first time and overall pregnancy rate. The threshold THI affecting the pregnancy rate was identified as THI 75. The months from October to March showed THI<75 and considered as non heat stress zone (NHSZ), while months from April to September were determined as heat stress zone (HSZ) with THI≥75. The lowest overall pregnancy rate (0.25) was obtained in July with THI 80.9, while the highest overall pregnancy rate (0.59) was found in November with THI 66.1. May and June were identified as critical heat stress zone (CHSZ) within the HSZ with maximum decline (−7%) in pregnancy rate with per unit increase in THI. The highest overall pregnancy rate was estimated as 0.45 in NHSZ with THI value 56.7 to 73.2. The pregnancy rate was found to have declined to 0.28 in HSZ with THI 73.5 to 83.7. However, the lowest pregnancy rate was estimated as 0.27 in CHSZ with THI value 80.3 to 81.6.

Influence of Temperature and Humidity on Pregnancy Rate of Murrah Buffaloes under Subtropical Climate

Dash, Soumya,Chakravarty, A.K.,Sah, V.,Jamuna, V.,Behera, R.,Kashyap, N.,Deshmukh, B. Asian Australasian Association of Animal Productio 2015 Animal Bioscience Vol.28 No.7

Heat stress has adverse effects on fertility of dairy animals. Decline in fertility is linearly associated with an increase in combination of both temperature and humidity. The purpose of this study was to investigate the relationship between temperature humidity index (THI) and the pregnancy rate of Murrah buffaloes in a subtropical climate. The effects of genetic and non-genetic factors viz., sire, parity, period of calving and age group at first calving were found non-significant on pregnancy rate. The effect of THI was found significant (p<0.001) on pregnancy rate of Murrah buffaloes calved for first time and overall pregnancy rate. The threshold THI affecting the pregnancy rate was identified as THI 75. The months from October to March showed THI<75 and considered as non heat stress zone (NHSZ), while months from April to September were determined as heat stress zone (HSZ) with $THI{\geq}75$. The lowest overall pregnancy rate (0.25) was obtained in July with THI 80.9, while the highest overall pregnancy rate (0.59) was found in November with THI 66.1. May and June were identified as critical heat stress zone (CHSZ) within the HSZ with maximum decline (-7%) in pregnancy rate with per unit increase in THI. The highest overall pregnancy rate was estimated as 0.45 in NHSZ with THI value 56.7 to 73.2. The pregnancy rate was found to have declined to 0.28 in HSZ with THI 73.5 to 83.7. However, the lowest pregnancy rate was estimated as 0.27 in CHSZ with THI value 80.3 to 81.6.

Snake venom neutralising factor from the root extract of $Emblica$ $officinalis$ $Linn.$

Sarkhel, S.,Chakravarty, A.K.,Das, R.,Gomes, Aparna,Gomes, A. 경희한의학연구센터 2011 Oriental Pharmacy and Experimental Medicine Vol.11 No.1

Detection of Polymorphism of Growth Hormone Gene for the Analysis of Relationship between Allele Type and Growth Traits in Karan Fries Cattle

Pal, Aruna,Chakravarty, A.K.,Bhattacharya, T.K.,Joshi, B.K.,Sharma, Arjava Asian Australasian Association of Animal Productio 2004 Animal Bioscience Vol.17 No.10

The present study was conducted to detect polymorphism at growth hormone gene in Karan Fries bulls. A 428 bp fragment of growth hormone gene spanning over $4^{th}$exon, $4^{th}$intron and $5^{th}$ exon was amplified and digested with AluI restriction enzyme to identify polymorphism at this locus. Karan Fries bulls were found to be polymorphic at this locus. Two genotypes LL and LV were identified in Karan Fries with higher allelic frequency for L allele. In Karan Fries males, the average birth weight, 3 months body weight and daily body weight gains of LL homozygotes were significantly higher than that of LV heterozygotes. Genetic distances of KF bulls with respect to genotype along with 3 months body weight and average daily body weight gain forms a single cluster of bulls with LL genotype, while individuals with LV genotype forms three distinct clusters indicating more influence of L allele on growth traits.

Snake venom neutralising factor from the root extract of Emblica officinalis Linn.

S. Sarkhel,A. K. Chakravarty,R. Das,Aparna Gomes,A. Gomes 경희대학교 융합한의과학연구소 2011 Oriental Pharmacy and Experimental Medicine Vol.11 No.1

The folk use of the Indian medicinal plant Emblica officinalis Linn. root extract and its active compound (Pthalate in nature) against snake venom has been established in experimental animal models. From the root extract of Emblica officinalis, a compound was isolated through silica gel column chromatography and the structure was determined by UV, IR, ^1H-NMR, ^(13)C-NMR & EIMS studies. The structure was determined and the active fraction was a pthalate compound, which could neutralize viper and cobra venom induced lethal, hemorrhagic,defibrinogenating, proinflammatory, PLA2, cardiotoxic and neurotoxic activity in experimental animal models. Viper venom induced myotoxicity was antagonized by the compound as shown by the decreased levels of the myotoxicity marker enzymes CPK & LDH. The proinflammatory action of viper venom neutralized by the active compound, showed the involvement of the proinflammatory markers IL-1, IL-6, TNF-α. The present study confirmed the phytomedicinal value of an antisnake venom compound present in the root of Emblica officinalis.

Observation of novel coexistence of Kondo effect and room temperature magnetism in AlN/Al/AlN trilayer thin film

Nath Deena,Chakravarty Sujay,Deshpade U.P.,Arasu A.V. Thanikai,Baskaran R.,Shekar N.V. Chandra 한국물리학회 2022 Current Applied Physics Vol.34 No.-

In this work for the first time, we are reporting the unusual observation of the Kondo effect with the coexistence of room temperature ferromagnetism in AlN/Al/AlN trilayer thin film. The grown film shows resistivity minimum at a temperature of ~48K, which shifts to the lower temperature on the application of magnetic fields. After considering various possibilities for an upturn in resistivity, we found that the Kondo scattering is responsible for upturn at low temperature. The simultaneous presence of ferromagnetism and Kondo scattering is explained by spatial variation of nitrogen vacancy defects from the film surface to the Al sandwich layer. Furthermore, magneto-transport properties of the film measured at different temperature exhibits both negative and positive components described by localized magnetic moment model for the spin scattering of carriers and two-band model, respectively. This work provides insight into the novel co-existence of ferromagnetism and Kondo effect in crystalline AlN.