http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : R. Chakravarty (검색결과 13 건)
- 무료
- 기관 내 무료
- 유료
-
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.
-
Tribofilm formation in ultrananocrystalline diamond film
Rani, R.,Sankaran, K.J.,Panda, K.,Kumar, N.,Ganesan, K.,Chakravarty, S.,Lin, I.N. Elsevier 2017 Diamond and related materials Vol.78 No.-
Friction and wear properties of ultrananocrystalline diamond (UNCD) films are found to be superior, and therefore it could be useful for various applications. However, understanding of the tribological properties with respect to boundary phase composition in this material is not yet well understood. Here, the grain boundary phases such as graphite and amorphous carbon (a-C) of UNCD films were tailored during the chemical vapor deposition process by altering the Argon and Nitrogen gases in CH<SUB>4</SUB> plasma medium. The significance of these grain boundary phases in UNCD film was discussed to explain the tribological properties. In run-in, friction coefficient was high in UNCD<SUB>Ar</SUB> film deposited in CH<SUB>4</SUB> (1%)/Ar plasma condition and it was decreased to lower value after longer sliding distance. However, ultrahigh wear resistance of this film was observed. Here, graphite and a-C phases were insignificant in the grain boundary region as evident from high resolution transmission electron microscope (HRTEM). Further, chemical bonding of these phases was quantitatively described by electron energy loss spectroscopy (EELS). In contrast, ultralow value of friction coefficient with significantly shorter run-in high friction regime was observed in UNCD<SUB>N</SUB> film deposited in CH<SUB>4</SUB> (6%)/N<SUB>2</SUB> plasma. Such a unique characteristic was described by the nanographite phase encasing the needle-like diamond grain of UNCD<SUB>N</SUB> film, forming core-shell granular structure. Atomic force microscopy (AFM) showed nucleation of two dimensional (2D) nanographite particles in the deformed wear track after run-in. This was possible due to the presence of core-shell granular structure in UNCD<SUB>N</SUB> film. Graphitic nature of the shell for needle-like diamond grains in the wear track was investigated by micro-Raman spectroscopy. Moreover, graphite and a-C tribofilm phase in the wear track was investigated by X-ray photoelectron spectroscopy (XPS) having spatial resolution micrometer scale. Needle-like diamond grains and graphite phase of tribofilm could be one of the primary reasons for the marked reduction in the friction coefficient.
-
-
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.
-
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.
-
Malik, Y.P.S.,Chakravarti, S.,Sharma, K.,Vaid, N.,Rajak, K.K.,Balamurugan, V.,Biswas, S.K.,Mondal, B.,Kataria, R.S.,Singh, R.K. Asian Australasian Association of Animal Productio 2011 Animal Bioscience Vol.24 No.7
Toll-like receptors (TLRs) play an important role in the recognition of invading pathogens and the modulation of innate immune responses in mammals. The TLR4 and TLR7 are well known to recognize the bacterial lipopolysaccharide (LPS) and single stranded (ssRNA) ligands, respectively and play important role in host defense against Gram-negative bacteria and ssRNA viruses. In the present study, coding exon fragments of these two TLRs were identified, cloned, sequenced and analyzed in terms of insertion-deletion polymorphism, within bovine TLRs 4 and 7, thereby facilitating future TLR signaling and association studies relevant to bovine innate immunity. Comparative sequence analysis of TLR 4 exons revealed that this gene is more variable, particularly the coding frame (E3P1), while other parts showed percent identity of 95.7% to 100% at nucleotide and amino acid level, respectivley with other Bos indicus and Bos taurus breeds from different parts of the world. In comparison to TLR4, sequence analysis of TLR7 showed more conservation among different B. indicus and B. taurus breeds, except single point mutation at 324 nucleotide position (AAA to AAM) altering a single amino acid at 108 position (K to X). Percent identity of TLR7 sequences (all 3 exons) was between 99.2% to 100% at nucleotide and amino acid level, when compared with available sequence database of B. indicus and B. taurus. Simple Modular Architecture Research Tool (SMART) analysis showed variations in the exon fragments located in the Leucine Rich Repeat (LRR) region, which is responsible for binding with the microbial associated molecular patterns and further, downstream signaling to initiate anti-microbial response. Considering importance of TLR polymorphism in terms of innate immunity, further research is warranted.
-
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.
-
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.
-
LAL THAKORE B.B.,SNEH MATHUR,R.B. SHINGH,B.P. CHAKRAVARTI 한국응용곤충학회 1987 한국응용곤충학회지 Vol.26 No.4
토양에 첨가한 8종의 Oil cake 중 Margosa, Undi, Karanj cake은 생강뿌리썩음병의 발생을 억제하였다. 생강수량의 증진효과는 Karanj, Roselle, Mustard cake의 순으로 높았다. Out of 8 oil cakes used for soil amendment, Margosa, Undi and Karanj cakes were found to reduce the ginger rot. However, maximum increase in yield was found in Karanj cake followed by Roselle and Mustard cakes.
-
Comparative Analysis of Different Grain Configurations for a Multi-thruster Kinetic Warhead
N. Ananthkrishnan,Hyun Ko,K. Sreesankar,R. Chakravarty,V.S. Renganathan 한국추진공학회 2016 한국추진공학회 학술대회논문집 Vol.2016 No.5
The S-DACS multi-thruster warhead consists of 4 divert and 6 attitude thrusters fed from a common gas generator. Successful S-DACS intercept requires careful selection of the internal ballistics (grain configuration, chamber pressure, etc.), the sensors (seeker range, guidance law, etc.) as well as the external ballistics and sizing (booster diameter, S-DACS release velocity, flight time, maneuverability, etc.). These requirements and constraints are inter-dependent making the S-DACS mission analysis and sizing a difficult task. This work explores the connections between the choice of S-DACS grain configuration and sizing with the chamber pressure as a key parameter. Various parameters and center of gravity/ moment of inertia variations are compared for three different S-DACS grain configurations. Keywords: DACS, grain configuration, mission analysis
DBpia
ScienceON연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
