X-ray Absorption Spectroscopic Studies of Pulsed-Laser-Deposited Thin Films of Fe3O4 on Si(111) Substrate

P. Thakur,W. K. Choi,K. H. Chae,J.-Y. Kim,R. J. Choudhary,Shailja Tiwari,Ram Prakash,D. M. Phase,Ravi Kumar 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.6

We report on the growth and the characterization of magnetite thin films grown on Si(111) substrates by using pulsed laser deposition at different substrate temperatures (TS = 350, 450 and 550 ℃) by performing X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) experiments. The O K− and Fe L3,2−edge XAS spectra reveal that the couplings of the O 2p with Fe 3d orbitals highly rely on the growth processes. The XMCD data of well-characterized thin films exhibit characteristic contributions from Fe3+ A ions in tetrahedral sites and Fe2+ B and Fe3+ B ions in octahedral sites and have spectral features similar to those of the Fe3O4 single crystal. The temperature dependence of the XMCD line shape features remain unchanged below and above the Verwey transition. These investigations demonstrate the experimental conditions for controlled growth of Fe3O4 thin films on Si(111) substrates and suggest that the Fe3O4/Si(111) might a promising spintronic materials for future technology.

Bimodal fibrous structures for tissue engineering: Fabrication, characterization and in vitro biocompatibility

Tiwari, A.P.,Joshi, M.K.,Kim, J.I.,Unnithan, A.R.,Lee, J.,Park, C.H.,Kim, C.S. Academic Press 2016 JOURNAL OF COLLOID AND INTERFACE SCIENCE - Vol.476 No.-

We report for the first time a polycaprolactone-human serum albumin (PCL-HSA) membrane with bimodal structures comprised of spider-web-like nano-nets and conventional fibers via facile electro-spinning/netting (ESN) technique. Such unique controllable morphology was developed by electrospinning the blend solution of PCL (8wt% in HFIP 1,1,1,3,3,3,-Hexafluoro-2-propanol) and HSA (10wt% deionized water). The phase separation during electrospinning caused the formation of bimodal structure. Various processing factors such as applied voltage, feeding rate, and distance between nozzle tip and collector were found responsible for the formation and distribution of the nano-nets throughout the nanofibrous mesh. Field emission electron microscopy (FE-SEM) confirmed that the nano-nets were composed of interlinked nanowires with an ultrathin diameter (10-30nm). When compared with a pure PCL membrane, the membrane containing nano-nets was shown to have better support for cellular activities as determined by cell viability and attachment assays. These results revealed that the blending of albumin, a hydrophilic biomolecule, with PCL, a hydrophobic polymer, proves to be an outstanding approach to developing membranes with controlled spider-web-like nano-nets for tissue engineering.

Temperature and Phase-space Density of a Cold Atom Cloud in a Quadrupole Magnetic Trap

S. P. Ram,S. R. Mishra,S. K. Tiwari,H. S. Rawat 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.4

We present studies on modifications in the temperature, number density and phase-space densitywhen a laser-cooled atom cloud from optical molasses is trapped in a quadrupole magnetic trap. Theoretically, for a given temperature and size of the cloud from the molasses, the phase-spacedensity in the magnetic trap is shown first to increase with increasing magnetic field gradient andthen to decrease with it after attaining a maximum value at an optimum value of the magneticfieldgradient. The experimentally-measured variation in the phase-space density in the magnetictrap with changing magnetic field gradient is shown to exhibit a similar trend. However, theexperimentally-measured values of the number density and the phase-space density are much lowerthan the theoretically-predicted values. This is attributed to the experimentally-observed temperaturein the magnetic trap being higher than the theoretically-predicted temperature. Nevertheless,these studies can be useful for setting a higher phase-space density in the trap by establishing anoptimal value of the field gradient for a quadrupole magnetic trap.

ECR plasma etching of GaAs in CCl2F2/Ar/O2 discharge and IR studies of the etched surface

L. S. S. Singh,K. P. Tiwary,R. K. Purohit,Z. H. Zaidi,M. Husain 한국물리학회 2005 Current Applied Physics Vol.5 No.4

The etching of GaAs materials under electron cyclotron resonance conditions has been performed in an ECR etching system withrf biasing using the CCl2F2/Ar/O2 plasma chemistry. Etching experiments were carried out at a pressure between 0.015 and 0.020mbar, rf power 0.39 W/cm2, and dc bias voltage 200 V. The surface morphology and etch depth were taken by scanning electronmicroscopy and Dektek Prolometry respectively. The use of ECR conditions with additional rf biasing provides the good etchingof the surface and fast etch rates. Moreover, the surface of the GaAs material display smooth and stoichiometric surfaces at higherECR powers. The surface damages on the GaAs samples after the plasma exposure have been studied using IR spectroscopy..

A Comparison of Pulsed and Continuous Atom Transfer between Two Magneto-optical Traps

S. P. Ram,S. K. Tiwari,S. R. Mishra 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.5

We present the experimental results for a comparison between pulsed and continuous transfer of cold 87Rb atoms between a vapor chamber magneto-optical trap (VC-MOT) and an ultra-highvacuum magneto-optical trap (UHV-MOT) when using a resonant push beam. We find that employing repetitive cycles of a pulsed and unfocused push beam on an unsaturated VC-MOT cloud results in a significantly higher number of atoms transferred to the UHV-MOT than the number obtained with a continuous push beam focused on a continuous VC-MOT. In pulsed transfer, we find that both the VC-MOT loading duration and the push beam duration play important roles in the transfer process and govern the number of atoms transferred to the UHV-MOT. The parameters and processes affecting the transfer have been investigated and are discussed.

Electrospun bioactive poly (@?-caprolactone)-cellulose acetate-dextran antibacterial composite mats for wound dressing applications

Liao, N.,Unnithan, A.R.,Joshi, M.K.,Tiwari, A.P.,Hong, S.T.,Park, C.H.,Kim, C.S. Elsevier 2015 Colloids and surfaces. A, Physicochemical and engi Vol.469 No.-

<P>Electrospun nanofibrous mat for wound dressing application was successfully prepared from poly (6caprolactone) (PCL), cellulose acetate (CA) and dextran blend solution. Incorporation of small amount of tetracycline hydrochloride (TCH), an antibacterial drug, improved the cell proliferation, enhanced blood clotting ability and cell attachment as well as antimicrobial activity of the composite mat. The composite mats were characterized by SEM, FTIR and TGA analysis. In order to evaluate the cytocompatibility and cell behavior of the composite scaffolds, fibroblast cells were seeded on the matrix. Results demonstrated that the incorporation of dextran and drug strongly enhanced the adhesion and proliferation of the cells on the composite nanofibers. The antimicrobial activity of the composite was studied by zone inhibition against Gram-positive and Gram-negative bacteria and the result indicates high antibacterial activity. Therefore, as synthesized composite fiber have decent characteristics for wound dressing and skin engineering applications. (C) 2015 Elsevier B.V. All rights reserved.</P>

Demographic Risk Factors, Affected Anatomical Sites and Clinicopathological Profile for Oral Squamous Cell Carcinoma in a North Indian Population

Krishna, Akhilesh,Singh, R.K.,Singh, Shraddha,Verma, Pratima,Pal, U.S.,Tiwari, Sunita Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.16

Background: Oral cancer is a common form of cancer in India, particularly among men. About 95% are squamous cell carcinomas. Tobacco along with alcohol are regarded as the major risk factors. Objectives: (i) To determine associations of oral squamous cell carcinoma (OSCC) with respect to gender, age group, socioeconomic status and risk habits; (ii) To observe the distribution of affected oral anatomical sites and clinico-pathological profile in OSCC patients. Materials and Methods: This is an unmatched case-control study during period January 2012 to December 2013. Total of 471 confirmed OSCC patients and 556 control subjects were enrolled. Data on socio-demography, risk habits with duration and medical history were recorded. Results: There were significant associations between OSCC with middle age (41-50years; unadjusted OR=1.63, 95%CI=1.05-2.52, p=0.02) (51-60 years; unadjusted OR=1.79, 95%CI=1.15-2.79, p=0.009) and male subjects (unadjusted OR=2.49, 95%CI=1.89-3.27, p=0.0001). Cases with both habits of tobacco chewing and smoking were at a higher risk for OSCC than tobacco chewing alone (unadjusted OR=0.52, 95%CI=0.38-0.72, p=0.0001), duration of risk habits also emerged as a responsible factor for the development of carcinoma. The majority of patients were presented in well-differentiated carcinomas (39.9%). Prevalence of advance stages (TNM stage III, IV) was 23.4% and 18.3% respectively. The buccal mucosa was the most common (35.5%) affected oral site. Conclusions: In most Asian countries, especially India, there is an important need to initiate the national level public awareness programs to control and prevent oral cancer by screening for early diagnosis and support a tobacco free environment.

Solar Science with the Atacama Large Millimeter/Submillimeter Array-A New View of Our Sun

Wedemeyer, S.,Bastian, T.,Brajš,a, R.,Hudson, H.,Fleishman, G.,Loukitcheva, M.,Fleck, B.,Kontar, E. P.,De Pontieu, B.,Yagoubov, P.,Tiwari, S. K.,Soler, R.,Black, J. H.,Antolin, P.,Scullion, E.,Gu Springer-Verlag 2016 Space science reviews Vol.200 No.1

<P>The Atacama Large Millimeter/submillimeter Array (ALMA) is a new powerful tool for observing the Sun at high spatial, temporal, and spectral resolution. These capabilities can address a broad range of fundamental scientific questions in solar physics. The radiation observed by ALMA originates mostly from the chromosphere-a complex and dynamic region between the photosphere and corona, which plays a crucial role in the transport of energy and matter and, ultimately, the heating of the outer layers of the solar atmosphere. Based on first solar test observations, strategies for regular solar campaigns are currently being developed. State-of-the-art numerical simulations of the solar atmosphere and modeling of instrumental effects can help constrain and optimize future observing modes for ALMA. Here we present a short technical description of ALMA and an overview of past efforts and future possibilities for solar observations at submillimeter and millimeter wavelengths. In addition, selected numerical simulations and observations at other wavelengths demonstrate ALMA's scientific potential for studying the Sun for a large range of science cases.</P>

Estrus Behavior and Superovulatory Response in Black Bengal Goats (Capra hircus) Following Administration of Prostaglandin and Gonadotropins

Mishra, O.P.,Gawande, P.G.,Nema, R.K.,Tiwari, S.K. Asian Australasian Association of Animal Productio 2004 Animal Bioscience Vol.17 No.10

The present study was conducted to explore the possibilities of estrus induction and superovulation in a native Indian breed of goats called 'Black Bengal'. Forty-two adult non-pregnant females were divided in two groups, of which 18 goats were subjected to a superovulatory treatment comprising of equine chorionic gonadotropin (eCG), Prostaglandin (PGF2$\alpha$) and human chorionic gonadotropin (hCG) to induce superovulation. The remaining 24 goats received no treatment and served as controls for the parameter under study as well as recipients for embryo transfer studies. The average duration of estrus was found to be significantly increased in treated goats (34.2${\pm}$3.4 h) compared to controls 3.0${\pm}$2.4 h). The average duration between PGF administration and occurrence of estrus was 2.0${\pm}$5.2 h. After mid ventral laparotomy, superovulatory responses indicated a significant increase in the number of follicles, which was 8.27${\pm}$0.37 in the treatment group compared to 4.16${\pm}$0.17 in the control group. The number of corpora lutea was also significantly increased in treated animals compared to control (2.90${\pm}$0.86 vs. 0.74${\pm}$0.04) respectively per ovary per goat.

Analgesic and Anti-inflammatory Activity of Carissa carandasLinn fruits and Microstylis wallichii Lindl Tubers

Alok Sharma,G.D. Reddy,Atul Kaushik,K.Shanker,R.K. Tiwari,Alok Mukherjee,Ch.V. Rao 한국생약학회 2007 Natural Product Sciences Vol.13 No.1

ethanolic (50% v/v) extracts of Carissa carandas (fruits) (Apocynaceae) and Microstylis wallichii(tubers) (Orchidaceae) were examined for anti-inflamatory and analgesic activities in experimental animals.Carissa carandas and Microstylis wallichii (50 - 200 mg/kg) caused a dose dependent inhibition of swellingcaused by carrageenin significantly in cotton pellet induced granuloma in rats (P < 0.05 to P < 0.001). There was asignificant increase in the analgesy meter induced pain in rats. The extracts of Carissa carandas and Microstyliswallichii resulted in an inhibition of stretching episodes and percentage protection was 16.05 - 17.58%respectively in acetic acid induced writhing.KeywordsCarissa carandas, Microstylis wallichii, pain, inflamation