Search

The inclusion of an additional U(1) gauge Lμ − Lτ symmetry would release the tension between the measured and the predicted value of the anomalous muon magnetic moment: this paradigm assumes the existence of a new, light Z′ vector boson, with dominant coupling to μ and τ leptons and interacting with electrons via a loop mechanism. The Lμ − Lτ model can also explain the Dark Matter relic abundance, by assuming that the Z′ boson acts as a “portal” to a new Dark Sector of particles in Nature, not charged under known interactions. In this work we present the results of the Z′ search performed by the NA64-e experiment at CERN SPS, that collected ~ 9 × 1011 100 GeV electrons impinging on an active thick target. Despite the suppressed Z′ production yield with an electron beam, NA64-e provides the first accelerator-based results excluding the g − 2 preferred band of the Z′ parameter space in the 1 keV < m Z ′ ≲ 2 MeV range, in complementarity with the limits recently obtained by the NA64-μ experiment with a muon beam. [ABSTRACT FROM AUTHOR]

Atomic scale study has been carried out to probe the pyrochlore phase formation in local scale and compare it with the long range ordering. Lanthanum zirconate (La2Zr2O7) pyrochlore was synthesized by wet chemistry and characterized by X-ray diffraction to study the long range ordering. Time Differential Perturbed γ-γ Angular Correlation (TDPAC) Spectroscopy was performed to identify the pyrochlore phase formation in local scale. Electron paramagnetic resonance and Photo-luminescence spectroscopic studies were used to identify the defects in local scale. Role of annealing and defects in nucleation of pyrochlore phase has been explored in the present study. An early identification of pyrochlore phase was successfully done by TDPAC spectroscopy. [ABSTRACT FROM AUTHOR]

Harmful chemical leach of plastics, such as Bisphenol A (BPA) and Bisphenol B (BPB), negatively affect public health. In fact, bisphenols in general affect the soil microbiome. In adddition, the antibacterial action of BPA on Escherichia coli has been reported. It is unknown whether BPB affects the growth of bacteria such as E. coli. Therefore, we have compared the impact of BPA and BPB on E. coli growth and its entire genome using in silico and in vitro strategies. We found that the E. coli growth was inhibited by both BPA and BPB. However, BPA caused greater inhibition of E. coli growth than BPB. More polymorphisms were introduced into the bacterial genome by BPA in comparison with BPB. In summary, our findings showed that both bisphenols can affect the microbiota in the environment and gut. Detailed research should be conducted to understand the effects of these harmful chemicals on the biosphere, particularly on microbiome components. [ABSTRACT FROM AUTHOR]

The present study reports the synthesis of amorphous carbon nanotube-Silica (a-CNT-SiO2) hybrids by a simple cost friendly method. The as synthesized samples were characterized by instruments like XRD, FESEM, FTIR spectroscopy, and Raman spectroscopy. The XRD spectra confirm the proper phase formation of the sample, whereas the FESEM micrographs reveal that the samples have been developed in cluster form. FTIR spectra reveal that there are several absorption peaks present these are mainly assigned to the Si–Si, Si–O, Si–H, C–C, C = C, C = O, C-Hn or OH bonds. Raman spectra of the pure and hybrid samples have also been studied in detail. From the application point of view, both the pure and hybrid samples have shown good efficacy in removing dyes like rhodamine B with an efficiency of over 90% within just 45 min. Kinetic studies confirmed that the reaction mostly followed pseudo first order mechanism. [ABSTRACT FROM AUTHOR]

T. M. Apostol introduced a certain Möbius function μ k (·) of order k, where k ≥ 2 is a fixed integer. Let k=1, then μ 1 (·) coincides with the Möbius function μ (·) , in the usual sense. For any fixed k ≥ 2 , he proved the asymptotic formula ∑ n ≤ x μ k (n) = A k x + O k (x 1 / k log x) as x → ∞ , where A k is a positive constant. Later, under the Riemann Hypothesis, D. Suryanarayana showed the O-term is O k (x 4 k 4 k 2 + 1 exp (D log x log log x ) ) with some positive constant D. In this paper, without using any unproved hypothesis we shall prove that the O-term obtained by Apostol can be improved to O k (x 1 / k exp (- D k (log x) 3 / 5 (log log x) 1 / 5 ) ) with some positive constant D k . [ABSTRACT FROM AUTHOR]

The escalation of zeta potential by the influence of wall slip for the electrokinetically modulated flow through a microchannel motivates to consider the impact of hydrodynamic slippage upon the zeta or surface potential. The reported study undergoes an analytical exploration of the pulsatile electroosmosis and shear-actuated flow characteristics of a fluid with a Newtonian model through a microchannel with parallel plates by invoking the reliance of a zeta or surface potential on slippage. The linearized Poisson-Boltzmann and momentum equations are solved analytically to obtain the explicit expression of the electrical potential induced in the electrical double layer (EDL), the flow velocity field, and the volumetric flow rate for an extensive span of parameters. The velocity field proximal to the microchannel wall is observed to enhance by an apparent zeta potential, and is further escalated for a thinner EDL and an oscillating electric field with a higher amplitude. However, near the core region of the microchannel, the flow velocity becomes invariant with the EDL thickness. The result shows that the lower wall velocity contributes to the flow velocity along with the electroosmotic body force and the impact of the velocity of the wall underneath diminishes proximal to the upper wall. Moreover, the volumetric flow rate increases when the thickness of the EDL decreases, owing to the influence of the wall slip. However, for thinner EDLs and medium and higher oscillating Reynolds numbers, the volumetric flow rate varies non-monotonously, correlative to the slip-free and slip cases. [ABSTRACT FROM AUTHOR]

Nuclear power is attracting renewed interest as an alternative power source because it is climate friendly with low greenhouse gas emissions, but its acceptance depends on the safe containment of nuclear waste under geological repositories. For the immobilization of high-level liquid waste (HLLW), borosilicate glass has been considered to be the preferred choice. Selecting suitable glass composition for the vitrification of HLLW is one of the major challenges in nuclear waste reprocessing. The fusion of valuable material properties has led to the acceptance of sodium borosilicate (NBS) glasses for nuclear waste immobilization. The mechanisms associated with these properties are only partially exposed and need further exploration. In that perspective, ZnO doping in borosilicate glasses was studied by performing experiments, classical molecular dynamics (MD), and ab-initio MD (AIMD) simulations. A significant change in glass structure was monitored from short-range order parameters (pair correlation function) and intermediate-range order parameters (angle distribution profiles). Order of connectivity illustrated that the hydrolysis of glass would slow down with the addition of ZnO in the glass matrix. Successively, the effect of microscopic structure on observable glass properties: chemical durability, mechanical strength, and thermal stability, was analyzed. Results show a good match of MD estimated trend for Young Modulus, glass transition temperature, and leaching data with the experimental observations, confirming the transferability of applied potential parameters for multi-component (n≥4) glasses. Both the experiments and MD simulations report the enhanced chemical durability of glass with ZnO addition. The enhanced chemical resistivity of Zn-NBS was also established from the increasing activation energy for the diffusion of Na ions. The combined studies from experiments and atomistic simulations disclose many fascinating microstructures and dynamics due to the presence of ZnO in the glass. The results presented here can be exploited to construe the experimental results and plan future experiments. The chemical, mechanical, and thermal strength of ZnO-incorporated sodium borosilicate glass was demonstrated by combined experiments and molecular dynamics (MD) simulations. The BKS interatomic potential was validated by ab-initio MD (AIMD) simulation. The results show the good mapping of MD-generated radial and angle distribution functions with the AIMD results. [ABSTRACT FROM AUTHOR]

Camphor-bistriazinyl pyridine (bis-2,6-(5,6,7,8-tetrahydro-5,9,9-trimethyl-5,8-methano-1,2,4-benzotriazin-3-yl) pyridine (CA-BTP)) was synthesized and used to prepare two different resins for extraction chromatography studies. CA-BTP/XAD-7 resin was prepared by the direct sorption of the extractant CA-BTP onto the inert XAD-7 support. In contrast, CA-BTP-Oct/XAD-7 resin was prepared such that a polar diluent 1-octanol was incorporated along with the extractant CA-BTP into the resin beads. The extraction performance of both these resins was investigated in batch studies to separate Am(III) from Eu(III) in acidic nitrate solutions. Comparing the results obtained for both the resins indicated that CA-BTP-Oct/XAD-7 resin has better selectivity for Am(III) over Eu(III). In extraction chromatography, the separation of Am(III) from Eu(III) was demonstrated using CA-BTP-Oct/XAD-7 resin. Am(III) was quantitatively recovered from the column with a Eu(III) contamination of only 9%. [ABSTRACT FROM AUTHOR]

We provide a simple proof of a Voronoi type identity using the Laplace transform for a class of arithmetical functions whose generating Dirichlet series satisfy a functional equation with gamma factors. As an application, we derivea Voronoi-type identity for Gaussian integers. [ABSTRACT FROM AUTHOR]

Endophytic fungi isolated from the insectivorous plant Drosera burmannii were tested for their antioxidant potential. The isolate Dro2 was found to have superlative antioxidant activity of the culture broth, scavenging 57.6 ± 0.2% of 2,2-diphenyl-1-picrylhydrazyl free radical. 5.8S rDNA homology led to identification of the isolate as a new strain and it has been named Mucor irregularis isolate Dro2. Optimization studies revealed ethyl acetate to be optimum for extraction of the antioxidant compounds. The crude solvent extract showed 89.6% 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radical scavenging activity with respect to 86.1% ABTS radical reducing antioxidant power of ascorbic acid. The sample exhibited 824.0 ± 25.5 µM reducing ability in assay, compared to 1204.0 ± 17.8 µM for ascorbic acid. The sample extract displayed IC50DPPH of 53.6 µg/mL. The crude extract was further purified through various chromatography techniques and GC-MS was performed on the purified active fractions to ascertain the nature and identify compounds conferring antioxidant potential to the endophytic fungal isolate. The active fractions were found to comprise multitudinous compounds with varied biological activity. Antioxidant compounds, such as 2,4-di-tert-butylphenol, myristic acid, pyrrolo[1,2-a]pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl)-, palmitic acid, were found in significant abundance. This study substantiates the candidature of the endophytic fungus Mucor irregularis isolate Dro2 as an industrially capable source for obtaining bioactive compounds, particularly antioxidant compounds. [ABSTRACT FROM AUTHOR]

The recently observed ferroelectricity in thin films of pure and doped Hafnium oxide (HfO2) has initiated a sustaining effort to stabilize its ferroelectric phase which is the polar orthorhombic (o) phase with space group Pca21. This polar o-phase of the oxide does not appear in its phase transition sequence and is also not thought to be stabilized in bulk oxide. Here, we report the stabilization of three o-phases of this oxide in bulk with space groups Pbca, Pca21 and Pbcm in presence of Yttrium (Y) dopant. For inducing o-phase, 10 at% of Y-dopant has been used and temperature mediated phase transformation from monoclinic (m) to o-phase has been observed. The third o-phase with space group Pbcm could be stabilized for the first time in bulk oxide by Y-dopant. All the o-phases in presence of m-phase could be identified by Time Differential Perturbed γ-γ Angular Correlation (TDPAC) Spectroscopy. The TDPAC parameters assigned to Pbcm phase confirm the theoretical modelization for the phase performed by Wien2K calculation based on Density Functional Theory (DFT). The present work reports the possibility of stabilizing different o-phases including polar one and shows the widening of scope of this oxide for future ferroelectric applications. [ABSTRACT FROM AUTHOR]

Modern observatories have revealed the ubiquitous presence of magnetohydrodynamic waves in the solar corona. The propagating waves (in contrast to the standing waves) are usually originated in the lower solar atmosphere which makes them particularly relevant to coronal heating. Furthermore, open coronal structures are believed to be the source regions of solar wind, therefore, the detection of MHD waves in these structures is also pertinent to the acceleration of solar wind. Besides, the advanced capabilities of the current generation telescopes have allowed us to extract important coronal properties through MHD seismology. The recent progress made in the detection, origin, and damping of both propagating slow magnetoacoustic waves and kink (Alfvénic) waves is presented in this review article especially in the context of open coronal structures. Where appropriate, we give an overview on associated theoretical modelling studies. A few of the important seismological applications of these waves are discussed. The possible role of Alfvénic waves in the acceleration of solar wind is also touched upon. [ABSTRACT FROM AUTHOR]

We report the results of a search for a new vector boson ( A ′ ) decaying into two dark matter particles χ 1 χ 2 of different mass. The heavier χ 2 particle subsequently decays to χ 1 and an off-shell Dark Photon A ′ ∗ → e + e - . For a sufficiently large mass splitting, this model can explain in terms of new physics the recently confirmed discrepancy observed in the muon anomalous magnetic moment at Fermilab. Remarkably, it also predicts the observed yield of thermal dark matter relic abundance. A detailed Monte-Carlo simulation was used to determine the signal yield and detection efficiency for this channel in the NA64 setup. The results were obtained re-analyzing the previous NA64 searches for an invisible decay A ′ → χ χ ¯ and axion-like or pseudo-scalar particles a → γ γ . With this method, we exclude a significant portion of the parameter space justifying the muon g-2 anomaly and being compatible with the observed dark matter relic density for A ′ masses from 2 m e up to 390 MeV and mixing parameter ε between 3 × 10 - 5 and 2 × 10 - 2 . [ABSTRACT FROM AUTHOR]

Flexible polymer (polyvinyl alcohol, PVA) nanofibres achieved with electrospinning and loaded with picosecond laser-ablated gold nanoparticles (Au NPs) were utilized as surface-enhanced Raman scattering (SERS) substrates. The fabricated polymer nanofibres and Au NPs were characterized by UV–Visible absorption, field emission scanning electron microscope, transmission electron microscopy and X-ray diffraction techniques. The PVA–Au NPs SERS substrates were used to detect the dye methylene blue (MB 5 µM) and a chemical warfare agent simulant (methyl salicylate) using a portable Raman spectrometer. The flexible PVA–Au NPs nanofibre exhibited a good sensitivity with enhancement factors of >104 and a high reproducibility (RSD ~10%). These flexible substrates could be extended for SERS studies of various explosive and other hazardous molecules. [ABSTRACT FROM AUTHOR]

Recently, the ATOMKI experiment has reported new evidence for the excess of e + e - events with a mass ∼ 17 MeV in the nuclear transitions of 4 He, that they previously observed in measurements with 8 Be. These observations could be explained by the existence of a new vector X 17 boson. So far, the search for the decay X 17 → e + e - with the NA64 experiment at the CERN SPS gave negative results. Here, we present a new technique that could be implemented in NA64 aiming to improve the sensitivity and to cover the remaining X 17 parameter space. If a signal-like event is detected, an unambiguous observation is achieved by reconstructing the invariant mass of the X 17 decay with the proposed method. To reach this goal an optimization of the X 17 production target, as well as an efficient and accurate reconstruction of two close decay tracks, is required. A dedicated analysis of the available experimental data making use of the trackers information is presented. This method provides independent confirmation of the NA64 published results [1], validating the tracking procedure. The detailed Monte Carlo study of the proposed setup and the background estimate show that the goal of the proposed search is feasible. [ABSTRACT FROM AUTHOR]

Present paper deals with evaluation of thermodynamic parameters like apparent molal volume and compressibility, thermal expansion coefficient, hydration number, heat of dilution from density, sound velocity measurements and calorimetric studies of Gd(NO3)3 solutions in aqueous medium and in presence of nitric acid of different strength. Nature of complex formed by Gd ions in aqueous medium in presence of varying concentrations of nitric acid, as revealed by changes in the thermodynamic parameters and its extraction profile, is also highlighted. [ABSTRACT FROM AUTHOR]

The quadrupole moments of the excited levels in neutron rich iodine isotopes, viz., 131 I (5/2 1 + ) and 132 I (3 1 + ), have been measured with LaBr 3 (Ce) detectors using Time Differential Perturbed Angular Correlation (TDPAC) spectroscopy. The excited levels were populated from β - decay of the radiochemically separated tellurium (Te) fission products produced in nat U( 4 He,f) reaction at E α (lab) = 40 MeV from K-130 cyclotron at VECC, Kolkata. The active tellurium fission products were radiochemically doped in metallic tellurium matrix to provide the necessary Electric Field Gradient (EFG) required for TDPAC measurement. The values of quadrupole moments for the 5/2 1 + level of 131 I and 3 1 + level of 132 I were determined to be (-) 0.30(1) eb and (−)0.25(2) eb, respectively. The present measurement provides the first experimental determination on the electric quadrupole moment of 5/2 1 + level of 131 I. [ABSTRACT FROM AUTHOR]

The current understanding of room temperature microplasticity in α/β titanium alloys is reviewed with a special emphasis on dual-phase engineering alloys. As the interplay between microstructure and deformation mechanisms governs both the microscale and macroscale mechanical response, a brief description of the main features of α/β microstructures is first provided. Elastic and plastic deformation in individual phases is then described. The complex interactions that govern the effect of grain boundaries, phase interfaces and microtexture on deformation behaviour are reviewed. Crystal plasticity simulations have evolved over the past decade as a key technique to obtain a mechanistic understanding of the deformation of Ti alloys. Micromechanical aspects are emphasized with a discussion of input parameters required to achieve realistic constitutive modeling. As microplasticity is especially relevant in cyclic loading such as experienced in-service by components, the current understanding of the relation of this regime with fatigue and dwell-fatigue behavior is briefly summarized in the final section. [ABSTRACT FROM AUTHOR]

Performance of 1″ × 1″ LaBr3 (5% Ce) scintillator coupled to Hamamatsu R2083 PM Tube has been investigated for the first time. Energy response and timing characteristics of the present assembly have been studied at different operating conditions for its application in fast timing spectroscopy. An energy resolution of 3.38 ± 0.03% at 662 keV γ-energy was obtained in the present work at a bias voltage of − 2800 V and a linear response could be observed up to a bias voltage of − 2500 V. Time resolution of a single LaBr3:Ce crystal was found to be 174 ± 2 ps and 121 ± 3 ps for 511–511 and 1173–1332 cascades respectively. Effect of applied bias voltage on the time resolution of the set up was studied and a steady improvement with increasing bias voltage was observed. Present results were compared with the previous results obtained with similar fast PM tubes and importance as well as implications of the present measurement were also discussed. [ABSTRACT FROM AUTHOR]

The measurement of B q 0 − B q 0 ¯ (q = d, s) mixing mass difference and decay width differences is an important ingredient for searching physics beyond the standard model. In this paper, we investigate B q 0 − B q 0 ¯ mixing mass and decay width differences in the Z′ model. It is found that these differences are enhanced relative to the standard model prediction and give signals for new physics. Depending upon the mass of Z′ boson, the Z′-mediated flavour-changing neutral current gives a contribution to mass and decay width differences in B q 0 − B q 0 ¯ mixing. [ABSTRACT FROM AUTHOR]

Present paper reports development of a simple procedure for estimation of 14C in irradiated graphite samples. The process utilizes decomposition of the graphite samples by heating followed by absorption of the generated carbon dioxide in ethanolamine and analysis using liquid scintillation analyzer. The interference due to tritium was removed by acid scrubbing. The optimized method has successfully been used for analysis of a large number of actual graphite samples irradiated in research reactor. The method can specifically be used for estimation of low active specimen and even in presence of fission products and activation products. [ABSTRACT FROM AUTHOR]

The content of the individual elements in the nanocomposite hard multicomponent coatings is known to affect the phase formation during deposition and the properties of the coatings. Silicon is one such element, which has been shown to improve or alter the properties of the nanocomposite hard coating systems. In the present work, we investigated the effect of Si addition on the microstructure, phase, and mechanical behavior of Ti-Si-B-C nanocomposite hard films deposited by direct current (DC) magnetron sputtering. X-ray photoelectron spectroscopy (XPS) analyses reveal that, with the increase of Si content, SiB4 and TiSi2 softer phases (compared to the hard phases of TiB2 and B4C) are formed. The Ti-Si-B-C films deposited with 13.4 at. pct Si content show maximum hardness ~ 32.55 GPa and modulus ~ 381.6 GPa. With the increase of Si content in the films, the hardness and modulus are decreased. The H/E ratio, which is a measure of materials' ability to take the strain prior to deformation, is also decreased with the increase of Si content, suggesting the lowering of toughness of the films with higher Si content. [ABSTRACT FROM AUTHOR]

Present work demonstrates, for the first time, the use of multiple probes in a single time differential perturbed angular correlation (TDPAC) measurement. Two different probes, viz., In/Cd and Hf/Ta, simultaneously have been incorporated in both pure rutile and Hafnium (Hf)-doped rutile Titanium Dioxide (TiO) systems following a soft chemical method. The rutile structure was identified by the hyperfine parameters, viz., quadrupole frequency ( ω ) and asymmetry ( η). Due to the doping of Hf at 5 and 10 at.%, the sample partially lost the purity of the crystal and the fact has been reflected at both the probe sites. [ABSTRACT FROM AUTHOR]

Four different cruciform sample designs, based on the work of Abu-Farha et al. (JOM 61:48, 2009) were studied. Key features of these designs are a recessed pocket with fillet and re-entrant corners. These samples were shown via digital image correlation to achieve widely differing strain values inside and outside the pocket. From the results of these tests, there are two competing failure mechanisms in the sample. The pocket region is affected by stress concentrations caused by the fillet, and re-entrant notches lead to strain-limited constraints similar to diffuse and localized necks in uniaxial samples. Balancing these two constraints determines the success or premature failure of the sample. [ABSTRACT FROM AUTHOR]

Copper hexacyanoferrate was imbued on pores of synthetic zeolite and the formation of needle shaped copper hexacyanoferrate microcrystals was confirmed by XRD and SEM. Batch equilibrations showed that the sorbent has good affinity for Cs and Sr which was further confirmed from column studies. It is established that a substantial amount (>8000 bed volumes) of low level waste contaminated with Cs and Sr can be treated in fixed bed column. The sorbent, owing to its low cost, simple preparation process and excellent Cs and Sr removal performance, is expected to find wide spread application in nuclear industry. [ABSTRACT FROM AUTHOR]

We detect and analyse transverse oscillations in a coronal loop, lying at the south-east limb of the Sun as seen from the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO). The jet is believed to trigger transverse oscillations in the coronal loop. The jet originates from a region close to the coronal loop on 19 September 2014 at 02:01:35 UT. The length of the loop is estimated to be between 377 - 539 Mm. Only one complete oscillation is detected with an average period of about $32\pm5~\mbox{min}$ . Using magnetohydrodynamic (MHD) seismologic inversion techniques, we estimate the magnetic field inside the coronal loop to be between $2.68\,\mbox{--}\,4.5~\mbox{G}$ . The velocity of the hot and cool components of the jet is estimated to be $168~\mbox{km}\,\mbox{s}^{-1}$ and $43~\mbox{km}\,\mbox{s}^{-1}$ , respectively. The energy density of the jet is found to be greater than the energy density of the oscillating coronal loop. We therefore conclude that the jet triggered transverse oscillations in the coronal loop. To our knowledge, this is the first coronal loop seismology study using the properties of a jet propagation to trigger oscillations. [ABSTRACT FROM AUTHOR]

The influence of viscosity gradient (via density) in an incompressible dusty plasma is analyzed. It is shown that for a well known dusty plasma model, the density dependence of viscosity leads to shear driven instability in a weakly coupled dusty plasma. The inhomogeneous viscous force coupled with density inhomogeneity in presence of velocity shear is responsible for this instability. For any finite value of shear flow parameter the viscous gradient force surpasses the viscous dissipation leading to instability. [ABSTRACT FROM AUTHOR]

Nanostructures of bismuth (Bi) are obtained by employing solvothermal process. Two different shapes, nanorods and nanospheres, are produced by changing the ratio of solvents (1) ethylene glycol (EG) and (2) EG and absolute ethanol (AE) in the ratio of 1:1, respectively. Prepared samples are characterized by X-ray diffraction, energy-dispersive X-ray spectroscopy and transmission electron microscopy. Transport properties measured on the pressed pellets of bismuth nanostructures exhibit metallic behavior. The room temperature conductivity varies from 64 to 18 S/cm depending on morphology of the nanostructure. The thermal conductivity is found to be ~50 times lower in nanostructures than that of single crystal bismuth. Thermoelectric performances like power factor and figure of merit are correlated with the porosities of the samples, which show higher value for sphere-like than that of rod-like Bi nanostructures. [ABSTRACT FROM AUTHOR]

During the total solar eclipse of 11 July 2010, multi-slit spectroscopic observations of the solar corona were performed from Easter Island, Chile. To search for high-frequency waves, observations were taken at a high cadence in the green line at 5303 Å that is due to [Fe xiv] and the red line at 6374 Å that is due to [Fe x]. The data were analyzed to study the periodic variations in intensity, Doppler velocity, and line width using wavelet analysis. The data with high spectral and temporal resolution enabled us to study the rapid dynamical changes within coronal structures. We find that at certain locations, each parameter shows significant oscillation with periods ranging from 6 - 25 s. For the first time, we were able to detect damping of high-frequency oscillations with periods of about 10 s. If the observed damped oscillations are due to magnetohydrodynamic waves, then they can contribute significantly to the heating of the corona. From a statistical study we try to characterize the nature of the observed oscillations while considering the distribution of power in different line parameters. [ABSTRACT FROM AUTHOR]

A comparison between a coronal hole (CH) and the adjacent quiet Sun (QS) has been performed using the spectroscopic diagnostics of the Hinode/EUV Imaging Spectrometer (EIS). Based on spectral signatures, we identify the coronal funnels that play an important role in the formation and propagation of the nascent fast solar wind. From the observed line profiles, we estimate the intensity, Doppler velocity, line width (FWHM), and electron density over CH and the adjacent QS region of a north polar coronal hole (NPCH). Excess-width regions (excess FWHM above a threshold level) have been identified in QS and CH. The plasma-flow inversion (average red-shifts changing to blue-shifts at a specific height) in CH and excess-width regions of QS take place at ${\approx}\,5.01\times10^{5}~\mbox{K}$. Furthermore, the high electron-density concentration in excess-width regions of QS provides an indication that these regions are the footprints of coronal funnels. We also find that non-thermal velocities of CH are higher in comparison to QS indicating that the CHs are the source regions of the fast solar wind. Doppler and non-thermal velocities, as recorded by different-temperature lines, have also been compared with previously published results. As we go from lower to the upper solar atmosphere, down-flows are dominant in the lower atmosphere, while coronal lines are dominated by up-flows with a maximum value of ≈ 10 - 12 km s in QS. The non-thermal velocity increases first but after $\log T_{e} = 5.47$ it decreases further in QS. This trend can be interpreted as a signature of the dissipation of Alfvén waves, while an increasing trend reported earlier may be attributed to the signature of the growth of Alfvén waves at lower heights. The predominance of the occurrence of nano-flares around the O vi formation temperature could also explain the non-thermal-velocity trend. [ABSTRACT FROM AUTHOR]

The precise prediction of the branching ratios of the very rare decays B → e e and B → e e is an important ingredient for high energy research beyond standard model (SM). Recently, the CDF collaboration has reported upper limits for the branching ratios B ( B → e e ) < 2.8 × 10 and B ( B → e e ) < 8.3 × 10 at 90 % confidence level. These branching ratios are approximately seven orders of magnitude larger than the SM predictions, providing in this way a direction in which the SM could be extended. In this paper, the B → e e and B → e e rare decays in flavor-changing Z′ model are studied. Our estimated branching ratios are enhanced from their SM values and provide signals for new physics. [ABSTRACT FROM AUTHOR]

Phosphoric acid fuel cell (PAFC) unit has been constructed to obtain the concentration-dependent proton conductivity at of aqueous phosphoric acid at different cell temperatures and fixed humidifier temperature. The proton conductivity of the acid has also been measured at different temperatures using an electrolysis cell. The experimental results obtained from different cells have been compared with the conductivity obtained from the theoretical simulation. The simulated proton conductivity values at different cell temperatures matched very well with that obtained from electrolysis cell. However, the proton conductivities obtained from PAFC unit are found to be three orders less than those of the simulated values which may be due to transport limitations. Geometry optimization and potential energy surface scans using ab initio calculations indicate that the proton transfer in the cell can be enhanced by the dilution of the phosphoric acid which significantly improves the generation of hydrogen bonds. [ABSTRACT FROM AUTHOR]

The GBAR project (Gravitational Behaviour of Anti hydrogen at Rest) at CERN, aims to measure the free fall acceleration of ultracold neutral anti hydrogen atoms in the terrestrial gravitational field. The experiment consists preparing anti hydrogen ions (one antiproton and two positrons) and sympathetically cooling them with B e ions to less than 10 μK. The ultracold ions will then be photo-ionized just above threshold, and the free fall time over a known distance measured. We will describe the project, the accuracy that can be reached by standard techniques, and discuss a possible improvement to reduce the vertical velocity spread. [ABSTRACT FROM AUTHOR]

Zr-doped HfO system has been studied with the nuclear probe technique time differential perturbed angular correlation (TDPAC). The effect of Zr-doping on the crystal structure of HfO has been investigated by doping the HfO matrix with 20 and 50 atom% of Zr. A mild and homogeneous chemical method was followed to prepare the doped samples so that the dopant Zr-atom gets uniformly distributed throughout the HfO matrix. It has been observed that the incorporation of Zr-atom into the HfO crystal system does not affect significantly up to 50 atom%. It has been explained in terms of similar arrangement of O-atoms around both Hf and Zr atoms in their oxide crystal structure. [ABSTRACT FROM AUTHOR]

The present study involved the assessment of potential generation of acid drainage from a coal mining area in India. Laboratory-based static and kinetic tests on overburden samples were conducted. Results of the static tests using acid base accounting indicate that all samples may be acid generators, and their generation capacity varied between likely, possible and low. To verify the acid generation potentiality of those samples showing a high acid drainage production in the static test, the kinetic test, using humidity cell, was conducted for a period of 15 weeks. The samples were leached with simulated rain water to mimic the chemical weathering under controlled laboratory conditions and imitate actual mine site leaching. Data obtained from chemical analysis of collected leachate were used to estimate production and reaction rates of acid generation and neutralizing capacity. Based on the kinetic test, it can be concluded that presently the neutralizing capacity of the samples is better than the oxidation capacity (acid generation). But due to the high weathering rate of carbonates, as reflected by the simulated leaching test, the neutralizing materials (carbonates) will eventually be exhausted earlier (since they showed dissolution rate) than the acid generation species (sulfates). Thus, acid drainage production is predicted from that point of time, when the neutralizing capacity has been exhausted for these mine sites. [ABSTRACT FROM AUTHOR]

Thermal behavior of the TiO shell in the core-shell Ag@TiO system has been investigated by the time differential perturbed angular correlation (TDPAC), transmission electron microscope and X-ray diffraction measurements in the temperature range from 473 to 1073 K. Although the thickness of the TiO shell increases on annealing, the TDPAC results show that the anatase phase persists till 1073 K. This is in contrast with the results for the pure TiO nanoparticles. These observations suggest that the phase transformation from anatase to rutile is hindered in case of core-shell nanoparticles possibly because the growth of the shell thickness in case of Ag@TiO nanoparticles is not effective for rutile formation due to the presence of Ag-core. [ABSTRACT FROM AUTHOR]

The characteristics of longitudinal dust acoustic wave (DAW) in presence of velocity shear have been investigated in a strongly coupled dusty plasma using the generalized hydrodynamic (GH) model. In the hydrodynamic regime ( ωτ≪1), i.e. when characteristic time τ is slower than inverse of wave frequency, the viscosity in the GH model plays the usual role of wave damping, whereas in the kinetic regime ( ωτ≫1), i.e. when characteristic time τ is larger than inverse of wave frequency, viscosity shows energy storing property in the wave. In the kinetic regime, we have studied the longitudinal mode $\omega^{2}=k^{2} (c_{d}^{2}+c_{l}^{2})$ (where ω is the frequency, k is the wave number, c is the dust acoustic velocity and c is the longitudinal velocity that arises due to viscosity) in presence of velocity shear. It is shown that velocity shear can destabilize this mode. Both nonmodal and modal techniques are employed to demonstrate the growth rate of the instability. [ABSTRACT FROM AUTHOR]

Recently, the first evidence for the decay B → μ μ has been announced by the LHCb Collaboration and the measured branching ratio B( → μ) = (3.2) × 10 is in good agreement with the standard model (SM) expectation. It has also reported an upper limit for B( B → μ μ) < 9.4 × 10 at 95% confidence level. In this paper, we study the B → μ μ and B → μ μ rare decays in flavor-changing Z′ model. Our estimated branching ratios are enhanced from their SM values and provide signals for new physics. [ABSTRACT FROM AUTHOR]

The Sun Watcher using Active Pixel system detector and Image Processing (SWAP) onboard the PRoject for OnBoard Autonomy-2 (PROBA2) spacecraft provides images of the solar corona in EUV channel centered at 174 Å. These data, together with the Atmospheric Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager (HMI) onboard Solar Dynamics Observatory (SDO), are used to study the dynamics of coronal bright points. The evolution of the magnetic polarities and associated changes in morphology are studied using magnetograms and multi-wavelength imaging. The morphology of the bright points seen in low-resolution SWAP images and high-resolution AIA images show different structures, whereas the intensity variations with time show similar trends in both SWAP 174 Å and AIA 171 Å channels. We observe that bright points are seen in EUV channels corresponding to a magnetic flux of the order of 10 Mx. We find that there exists a good correlation between total emission from the bright point in several UV-EUV channels and total unsigned photospheric magnetic flux above certain thresholds. The bright points also show periodic brightenings, and we have attempted to find the oscillation periods in bright points and their connection to magnetic-flux changes. The observed periods are generally long (10 - 25 minutes) and there is an indication that the intensity oscillations may be generated by repeated magnetic reconnection. [ABSTRACT FROM AUTHOR]

Spectroscopic studies of the solar corona, using the high spatial and spectral resolution 25-cm coronagraph at the Norikura Solar Observatory for equatorial off-limb observations, indicated that the variation of radiance and line width with height is different for different temperature lines. The line width of the forbidden red emission line [Fe x] 6374 Å was found to increase with height, and that of the green emission line [Fe xiv] 5303 Å decreased with height. This had been interpreted in terms of the interaction between different temperature plasmas but needed to be confirmed. Further observations were made on several days during 2004, in two emission lines simultaneously covering the mid-latitude and polar regions to investigate the existence of the observed variation in other parts of the solar corona. In this study, we have analysed several raster scans that cover mid- and high-latitude regions of the off-limb corona in all four bright emission lines [Fe x] 6374 Å, [Fe xi] 7892 Å, [Fe xiii] 10747 Å, and [Fe xiv] 5303 Å. We find that the FWHM of the red line increases with height and that of the green line decreases with height, similar to the observations in the equatorial regions. The line widths are higher in the polar regions for all of the observed emission lines except the green line. Higher values of FWHM in polar regions may imply higher non-thermal velocities, which could be further linked to a non-thermal source powering the solar-wind acceleration, but the reason for the behaviour of the green emission line remains to be explored. [ABSTRACT FROM AUTHOR]

Silicon nanowire is an important material for the potential use as a cold cathode, but there are some bottlenecks like oxidation of the surface during field emission thereby degradation of its performance. To compete with carbon based nanostructures in this field the performance of Si nanowires as field emitter should be improved. Here, we report a simple technique for the significant improvement of field emission properties of Si nanowires by ZnO nanoparticle coating. Boron-doped p-type Si wafers were chemically etched to synthesize vertically aligned silicon nanowires and they were coated with different thicknesses of ZnO layer by radio frequency magnetron sputtering technique. The nanostructured thin films were studied by X-ray photoelectron spectroscopy for compositional and valence states information while their morphological information was obtained by a field emission scanning electron microscope and a high resolution transmission electron microscope. The field assisted electron emission performance of Si nanowires significantly improved for the thickness optimized ZnO coating. The photoluminescence spectra showed a peak at ~558 nm assigned to surface defect states of ZnO and the field emission from Si nanowires coated with ZnO for different times were correlated with the surface defect structures. The mechanism of such improvement is also discussed. [ABSTRACT FROM AUTHOR]

We study the nature of quiet-Sun oscillations using multi-wavelength observations from TRACE, Hinode, and SOHO. The aim is to investigate the existence of propagating waves in the solar chromosphere and the transition region by analyzing the statistical distribution of power in different locations, e.g. in bright magnetic (network), bright non-magnetic and dark non-magnetic (inter-network) regions, separately. We use Fourier power and phase-difference techniques combined with a wavelet analysis. Two-dimensional Fourier power maps were constructed in the period bands 2 - 4 minutes, 4 - 6 minutes, 6 - 15 minutes, and beyond 15 minutes. We detect the presence of long-period oscillations with periods between 15 and 30 minutes in bright magnetic regions. These oscillations were detected from the chromosphere to the transition region. The Fourier power maps show that short-period powers are mainly concentrated in dark regions whereas long-period powers are concentrated in bright magnetic regions. This is the first report of long-period waves in quiet-Sun network regions. We suggest that the observed propagating oscillations are due to magnetoacoustic waves, which can be important for the heating of the solar atmosphere. [ABSTRACT FROM AUTHOR]