Showing papers by "University of Rajasthan published in 2011"

Centrality Dependence of the Charged-Particle Multiplicity Density at Midrapidity in Pb-Pb Collisions at root s(NN)=2.76 TeV

Abstract: The centrality dependence of the charged-particle multiplicity density at midrapidity in Pb-Pb collisions at root s(NN) = 2: 76 TeV is presented. The charged-particle density normalized per participating nucleon pair increases by about a factor of 2 from peripheral (70%-80%) to central (0%-5%) collisions. The centrality dependence is found to be similar to that observed at lower collision energies. The data are compared with models based on different mechanisms for particle production in nuclear collisions.

Higher harmonic anisotropic flow measurements of charged particles in Pb-Pb collisions at root s(NN)=2.76 TeV

Abstract: We report on the first measurement of the triangular nu(3), quadrangular nu(4), and pentagonal nu(5) charged particle flow in Pb-Pb collisions at root s(NN) = 2.76 TeV measured with the ALICE detector at the CERN Large Hadron Collider. We show that the triangular flow can be described in terms of the initial spatial anisotropy and its fluctuations, which provides strong constraints on its origin. In the most central events, where the elliptic flow nu(2) and nu(3) have similar magnitude, a double peaked structure in the two-particle azimuthal correlations is observed, which is often interpreted as a Mach cone response to fast partons. We show that this structure can be naturally explained from the measured anisotropic flow Fourier coefficients.

Flavonoids: A Versatile Source of Anticancer Drugs

Abstract: An exponential increase in the number of studies investigating how different components of the diet interact at the molecular and cellular level to determine the fate of a cell has been witnessed. In search for anticancer drugs compelling data from laboratories, epidemiologic investigations, and human clinical trials showed that flavonoids have important effects on cancer chemoprevention and chemotherapy. In many molecular mechanisms of action for prevention against cancer, flavonoids play a major role by interacting between different types of genes and enzymes. Many mechanisms of action have been identified, including carcinogen inactivation, antiproliferation, cell cycle arrest, induction of apoptosis, inhibition of angiogenesis, antioxidation, and reversal of multidrug resistance or a combination of these mechanisms. This review focuses on the anticancer activity of flavonoids as well as their molecular mechanisms, including the treatment of mammary and prostate cancer. This review also highlights some advanced derivatives of flavonoids, which play an important role against cancer.

Antidiabetic and antioxidant potential of β-sitosterol in streptozotocin-induced experimental hyperglycemia.

Abstract: Background: Oxidative stress, produced under diabetic conditions, may cause tissue damage. Although several drugs are currently available for the treatment of diabetes, their continued use may cause unwanted side effects. The aim of the present study was to evaluate the antioxidant potential of β-sitosterol (BS), a phytosterol from Solanum surattense, using an experimental model for diabetes-induced oxidative damage. Methods: The effects of 21 days treatment with BS (10, 15 and 20 mg/kg, p.o.) on blood, serum, and tissue biochemical parameters were evaluated in control and streptozotocin-induced diabetic rats. Nine experimental groups, including a control group, a diabetic group, and BS- and glibenclamide-treated diabetic groups, were evaluated. Results: All three dose levels dose dependently resulted in decreases in glycated hemoglobin, serum glucose, and nitric oxide, with concomitant increases in serum insulin levels. Furthermore, treatment with BS doses also increased pancreatic antioxidant levels, with a concomitant decrease in thiobarbituric acid-reactive substances. Conclusions: β-Sitosterol has promising antidiabetic as well as antioxidant effects and may be considered in clinical studies for drug development.

Production of pions, kaons and protons in pp collisions at root s=900 GeV with ALICE at the LHC

Abstract: The production of π+, π−, K+, K−, p, and \(\overline{\mathrm{p}}\) at mid-rapidity has been measured in proton-proton collisions at \(\sqrt{s} = 900~\mathrm{GeV}\) with the ALICE detector. Particle identification is performed using the specific energy loss in the inner tracking silicon detector and the time projection chamber. In addition, time-of-flight information is used to identify hadrons at higher momenta. Finally, the distinctive kink topology of the weak decay of charged kaons is used for an alternative measurement of the kaon transverse momentum (pt) spectra. Since these various particle identification tools give the best separation capabilities over different momentum ranges, the results are combined to extract spectra from pt=100 MeV/c to 2.5 GeV/c. The measured spectra are further compared with QCD-inspired models which yield a poor description. The total yields and the mean pt are compared with previous measurements, and the trends as a function of collision energy are discussed.

Strange particle production in proton-proton collisions at root s=0.9 TeV with ALICE at the LHC

Abstract: The production of mesons containing strange quarks ($\Kzs$, $\phi$) and both singly and doubly strange baryons ($\rmLambda$, $\rmAlambda$, and $\Xis$) are measured at central rapidity in pp collisions at $\sqrt{s}$ = 0.9 $\tev$ with the ALICE experiment at the LHC. The results are obtained from the analysis of about 250 k minimum bias events recorded in 2009. Measurements of yields (dN/dy) and transverse momentum spectra at central rapidities for inelastic pp collisions are presented. For mesons, we report yields ($ $) of $0.184 \pm 0.002 \stat \pm 0.006 \syst$ for $\Kzs$ and $0.021 \pm 0.004 \stat \pm 0.003 \syst$ for $\phi$. For baryons, we find $ = 0.048 \pm 0.001 \stat \pm 0.004 \syst$ for $\rmLambda$, $0.047 \pm 0.002 \stat \pm 0.005 \syst$ for $\rmAlambda$ and $0.0101 \pm 0.0020 \stat \pm 0.0009 \syst$ for $\Xis$. The results are also compared with predictions for identified particle spectra from QCD-inspired models and provide a baseline for comparisons with both future pp measurements at higher energies and heavy-ion collisions.

Observation of the antimatter helium-4 nucleus

Abstract: High-energy nuclear collisions create an energy density similar to that of the Universe microseconds after the Big Bang(1); in both cases, matter and antimatter are formed with comparable abundance. However, the relatively short-lived expansion in nuclear collisions allows antimatter to decouple quickly from matter, and avoid annihilation. Thus, a high-energy accelerator of heavy nuclei provides an efficient means of producing and studying antimatter. The antimatter helium-4 nucleus ((4)(He) over bar), also known as the anti-alpha ((alpha) over bar), consists of two antiprotons and two antineutrons (baryon number B = -4). It has not been observed previously, although the alpha-particle was identified a century ago by Rutherford and is present in cosmic radiation at the ten per cent level(2). Antimatter nuclei with B -1 have been observed only as rare products of interactions at particle accelerators, where the rate of antinucleus production in high-energy collisions decreases by a factor of about 1,000 with each additional antinucleon(3-5). Here we report the observation of (4)<(He) over bar, the heaviest observed antinucleus to date. In total, 18 (4)(He) over bar counts were detected at the STAR experiment at the Relativistic Heavy Ion Collider (RHIC; ref. 6) in 10(9) recorded gold-on-gold (Au+Au) collisions at centre-of-mass energies of 200 GeV and 62 GeV per nucleon-nucleon pair. The yield is consistent with expectations from thermodynamic(7) and coalescent nucleosynthesis(8) models, providing an indication of the production rate of even heavier antimatter nuclei and a benchmark for possible future observations of (4)(He) over bar in cosmic radiation.

Recent advances in 1,4-benzoquinone chemistry

Abstract: 1,4-Benzoquinones are ubiquitous in nature and can be synthesized by diverse strategies. Recent developments on their synthetic methodologies, cycloaddition reactions, computational chemistry and pulse radiolytic studies are reported in this review. Their chemical and biological significance as well as their derivates' are also covered.

A Simple and Effective Modification of PCBM for Use as an Electron Acceptor in Efficient Bulk Heterojunction Solar Cells

Abstract: [6,6]-phenyl-C-61-butyric acid methyl ester (PCBM) and poly(3-hexylthiophene) (P3HT) are the most widely used acceptor and donor materials, respectively, in polymer solar cells (PSCs). However, the low LUMO (lowest unoccupied molecular orbital) energy level of PCBM limits the open circuit voltage (Voc) of the PSCs based on P3HT. Herein a simple, low-cost and effective approach of modifying PCBM and improving its absorption is reported which can be extended to all fullerene derivatives with an ester structure. In particular, PCBM is hydrolyzed to carboxylic acid and then converted to the corresponding carbonyl chloride. The latter is condensed with 4-nitro-4’-hydroxy-α-cyanostilbene to afford the modified fullerene F. It is more soluble than PCBM in common organic solvents due to the increase of the organic moiety. Both solutions and thin films of F show stronger absorption than PCBM in the range of 250–900 nm. The electrochemical properties and electronic energy levels of F and PCBM are measured by cyclic voltammetry. The LUMO energy level of F is 0.25 eV higher than that of PCBM. The PSCs based on P3HT with F as an acceptor shows a higher Voc of 0.86 V and a short circuit current (Jsc) of 8.5 mA cm−2, resulting in a power conversion efficiency (PCE) of 4.23%, while the PSC based on P3HT:PCBM shows a PCE of about 2.93% under the same conditions. The results indicate that the modified PCBM, i.e., F, is an excellent acceptor for PSC based on bulk heterojunction active layers. A maximum overall PCE of 5.25% is achieved with the PSC based on the P3HT:F blend deposited from a mixture of solvents (chloroform/acetone) and subsequent thermal annealing at 120 °C.

Femtoscopy Of Pp Collisions At √s=0.9 And 7 Tev At The Lhc With Two-pion Bose-einstein Correlations

Abstract: We report on the high statistics two-pion correlation functions from pp collisions at root s = 0.9 TeV and root s = 7 TeV, measured by the ALICE experiment at the Large Hadron Collider. The correlation functions as well as the extracted source radii scale with event multiplicity and pair momentum. When analyzed in the same multiplicity and pair transverse momentum range, the correlation is similar at the two collision energies. A three-dimensional femtoscopic analysis shows an increase of the emission zone with increasing event multiplicity as well as decreasing homogeneity lengths with increasing transverse momentum. The latter trend gets more pronounced as multiplicity increases. This suggests the development of space-momentum correlations, at least for collisions producing a high multiplicity of particles. We consider these trends in the context of previous femtoscopic studies in high-energy hadron and heavy-ion collisions and discuss possible underlying physics mechanisms. Detailed analysis of the correlation reveals an exponential shape in the outward and longitudinal directions, while the sideward remains a Gaussian. This is interpreted as a result of a significant contribution of strongly decaying resonances to the emission region shape. Significant nonfemtoscopic correlations are observed, and are argued to be the consequence of "mini-jet"-like structures extending to low p(t). They are well reproduced by the Monte-Carlo generators and seen also in pi(+)pi(-) correlations.

Strange and multistrange particle production in Au + Au collisions at √sNN=62.4 GeV

Abstract: We present results on strange and multistrange particle production in Au + Au collisions at root s(NN) = 62.4 GeV as measured with the STAR detector at RHIC. Midrapidity transverse momentum spectra and integrated yields of K-S(0), Lambda, Xi, and Omega and their antiparticles are presented for different centrality classes. The particle yields and ratios follow a smooth energy dependence. Chemical freeze-out parameters, temperature, baryon chemical potential, and strangeness saturation factor obtained from the particle yields are presented. Intermediate transverse momentum (p(T)) phenomena are discussed based on the ratio of the measured baryon-to-meson spectra and nuclear modification factor. The centrality dependence of various measurements presented show a similar behavior as seen in Au + Au collisions at root s(NN) = 200 GeV.

K*0 production in Cu + Cu and Au + Au collisions at √sNN=62.4 GeV and 200 GeV

Abstract: We report on K*(0) production at midrapidity in Au + Au and Cu + Cu collisions at root s(NN) = 62.4 and 200 GeV collected by the Solenoid Tracker at the Relativistic Heavy Ion Collider detector. The K*(0) is reconstructed via the hadronic decays K*(0) -> K+pi(-) and (K*(0)) over bar -> K+pi(-). Transverse momentum, p(T), spectra are measured over a range of p(T) extending from 0.2 GeV/c up to 5 GeV/c. The center-of-mass energy and system size dependence of the rapidity density, dN/dy, and the average transverse momentum, , are presented. The measured N(K*(0))/N(K) and N(phi)/N(K*(0)) ratios favor the dominance of rescattering of decay daughters of K*(0) over the hadronic regeneration for the K*(0) production. In the intermediate p(T) region (2.0 < p(T) < 4.0 GeV/c), the elliptic flow parameter, v(2), and the nuclear modification factor, R-CP, agree with the expectations from the quark coalescence model of particle production.

Low band gap conjugated small molecules containing benzobisthiadiazole and thienothiadiazole central units: synthesis and application for bulk heterojunction solar cells

Abstract: Two novel conjugated low band gap small molecules (SMs), M1 and M2, containing benzobisthiadiazole and thienothiadiazole central units, respectively, were synthesized. Both SMs carried terminal cyanovinylene 4-nitrophenyl at both sides which were connected to the central unit with a thiophene ring. The long-wavelength absorption band was located at 591–643 nm and the optical band gap was 1.62–1.63 eV, which is lower than that of P3HT. These two SMs were investigated as electron donor materials along with PCBM or F as electron acceptors for fabrication of bulk heterojunction (BHJ) organic photovoltaic devices. F is a modified PCBM which has been previously synthesized and used as an electron acceptor for poly(3-hexylthiophene) (P3HT). The power conversion efficiency (PCE) for M1:PCBM, M1:F, M2:PCBM and M2:F was 1.05%, 2.02%, 1.23% and 2.72%, respectively. The higher PCE for the devices with M2 as the electron donor has been related to the improved hole mobility for M2. However, the improved PCE for the devices with F as the electron acceptor has been attributed to the more intense absorption of F in the visible region than that of PCBM and also to the higher open circuit voltage resulting from the higher LUMO level of F. We have also fabricated devices with M2:F cast film from mixed solvents. The PCE for the BHJ devices with the as cast and thermally annealed M2:F (mixed solvents) is 3.34% and 3.65%, respectively.

Atherothrombotic risk factors & premature coronary heart disease in India: A case-control study

Abstract: Coronary heart disease (CHD) is epidemic in India1 characterized by premature onset and high mortality. The World Health Organization (WHO) reports that while more than 70 per cent of coronary deaths occur in subjects older than 70 yr in North America and Western Europe, in India and other developing countries 70 per cent deaths occur in subjects less than 70 yr of age1. Factors of risk for the premature CHD in Indian subjects could be multiple, ranging from social, economic, psychological, lifestyle (smoking, sedentary lifestyle, improper diet) and biological (abnormal lipids, hypertension, diabetes, obesity)2. Genetic factors such as mutations at specific chromosomal locations and single nucleotide polymorphisms have also been implicated3. The INTERHEART case-control study reported that nine established risk factors (high apolipoprotein B/A1 ratio, smoking, hypertension, diabetes, obesity, psychosocial stress, low fruit and vegetables intake, low alcohol intake and sedentary lifestyle), explained more than 90 per cent of acute myocardial infarction4. Prospective cohort studies in developed countries have identified that five major cardiovascular risk factors (smoking, hypertension, high LDL cholesterol, low HDL cholesterol and diabetes) are associated with CHD5. These studies also reported that more than 90 per cent of acute coronary events can be predicted by major coronary risk factors5. Previous case-control studies from India have reported importance of smoking, hypertension, diabetes, and abnormal lipids6–9. Individual studies have also studied novel risk factors such as lipid subtypes, lipoprotein(a), insulin resistance, homocysteine, and dietary factors2. Large studies for identification of risk factors for premature CHD among Indian subjects are not available and most are limited to 50-100 subjects1,2. We hypothesized that thrombogenic risk factors (e.g., smoking, dietary antioxidant deficiency, fibrinogen, platelet functions, etc.) are important in premature CHD in Indians. To test this hypothesis a case-control study was performed to identify association of multiple vascular risk factors, both thrombogenic and atherogenic, in subjects (≤55 yr age) with an acute coronary event (myocardial infarction or unstable angina) or recent angina.

Radiation-Induced Testicular Injury and Its Amelioration by Tinospora cordifolia (An Indian Medicinal Plant) Extract

Abstract: The primary objective of this investigation is to determine the deleterious effects of sub lethal gamma radiation on testes and their possible inhibition by Tinospora cordifolia extract (TCE). For this purpose, one group of male Swiss albino mice was exposed to 7.5 Gy gamma radiation to serve as the irradiated control, while the other group received TCE (75 mg/kg b. wt./day) orally for 5 consecutive days half an hr before irradiation to serve as experimental. Exposure of animals to 7.5 Gy gamma radiation resulted into significant decrease in body weight, tissue weight, testes- body weight ratio and tubular diameter up to 15 days of irradiation. Cent percent mortality was recorded by day 17th in irradiated control, whereas all animals survived in experimental group. TCE pretreatment rendered significant increase in body weight, tissue weight, testes- body weight ratio and tubular diameter at various intervals as compared to irradiated group. Radiation induced histological lesions in testicular architecture were observed more severe in irradiated control then the experimental. TCE administration before irradiation significantly ameliorated radiation induced elevation in lipid peroxidation and decline in glutathione concentration in testes. These observations indicate the radio- protective potential of Tinospora cordifolia root extract in testicular constituents against gamma irradiation in mice.