Synergistic use of thermogravimetric and electrochemical techniques for thermodynamic study of TiOx (1.67 <= x <= 2.0) at 1573 K

A thermodynamic study of the Ti-O system at 1573 K has been conducted using a combination of thermogravimetric and emf techniques. The results indicate that the variation of oxygen potential with the nonstoichiometric parameter delta in stability domain of TiO2-delta with rutile structure can be represented by the relation, Delta mu o(2) = -6RT In delta - 711970(+/-1600) J/mol. The corresponding relation between non-stoichiometric parameter delta and partial pressure of oxygen across the whole stability range of TiO2-delta at 1573 K is delta proportional to P-O2(-1/6). It is therefore evident that the oxygen deficient behavior of nonstoichiometric TiO2-delta is dominated by the presence of doubly charged oxygen vacancies and free electrons. The high-precision measurements enabled the resolution of oxygen potential steps corresponding to the different Magneli phases (Ti-n O2n-1) up to n = 15. Beyond this value of n, the oxygen potential steps were too small to be resolved. Based on composition of the Magneli phase in equilibrium with TiO2-delta, the maximum value of n is estimated to be 28. The chemical potential of titanium was derived as a function of composition using the Gibbs-Duhem relation. Gibbs energies of formation of the Magneli phases were derived from the chemical potentials of oxygen and titanium. The values of -2441.8(+/-5.8) kJ/mol for Ti4O7 and -1775.4(+/-4.3) kJ/mol for Ti3O5 Obtained in this study refine values of -2436.2(+/-26.1) kJ/mol and-1771.3(+/-6.9) kJ/mol, respectively, given in the JANAF thermochemical tables.

Communication pathways from the anti-codon region to the aminoacylation site in Methionyl tRNA Synthetase: Molecular dynamics simulations and the structure network analysis

The enzymes of the family of tRNA synthetases perform their functions with high precision by synchronously recognizing the anticodon region and the aminoacylation region, which are separated by ?70 in space. This precision in function is brought about by establishing good communication paths between the two regions. We have modeled the structure of the complex consisting of Escherichia coli methionyl-tRNA synthetase (MetRS), tRNA, and the activated methionine. Molecular dynamics simulations have been performed on the modeled structure to obtain the equilibrated structure of the complex and the cross-correlations between the residues in MetRS have been evaluated. Furthermore, the network analysis on these simulated structures has been carried out to elucidate the paths of communication between the activation site and the anticodon recognition site. This study has provided the detailed paths of communication, which are consistent with experimental results. Similar studies also have been carried out on the complexes (MetRS + activated methonine) and (MetRS + tRNA) along with ligand-free native enzyme. A comparison of the paths derived from the four simulations clearly has shown that the communication path is strongly correlated and unique to the enzyme complex, which is bound to both the tRNA and the activated methionine. The details of the method of our investigation and the biological implications of the results are presented in this article. The method developed here also could be used to investigate any protein system where the function takes place through long-distance communication.

Finite element estimation of elastic interlaminar stresses in laminates

Low interlaminar strength and the consequent possibility of interlaminar failures in composite laminates demand an examination of interlaminar stresses and/or strains to ensure their satisfactory performance. As a first approximation, these stresses can be obtained from thickness-wise integration of ply equilibrium equations using in-plane stresses from the classical laminated plate theory. Implementation of this approach in the finite element form requires evaluation of third and fourth order derivatives of the displacement functions in an element. Hence, a high precision element developed by Jayachandrabose and Kirkhope (1985) is used here and the required derivatives are obtained in two ways. (i) from direct differentiation of element shape functions; and (ii) by adapting a finite difference technique applied to the nodal strains and curvatures obtained from the finite element analysis. Numerical results obtained for a three-layered symmetric and a two-layered asymmetric laminate show that the second scheme is quite effective compared to the first scheme particularly for the case of asymmetric laminates.

Paleoseismological evidence of surface faulting along the northeastern Himalayan front, India: Timing, size, and spatial extent of great earthquakes

The similar to 2500 km long Himalayan arc has experienced three large to great earthquakes of M-w 7.8 to 8.4 during the past century, but none produced surface rupture. Paleoseismic studies have been conducted during the last decade to begin understanding the timing, size, rupture extent, return period, and mechanics of the faulting associated with the occurrence of large surface rupturing earthquakes along the similar to 2500 km long Himalayan Frontal Thrust (HFT) system of India and Nepal. The previous studies have been limited to about nine sites along the western two-thirds of the HFT extending through northwest India and along the southern border of Nepal. We present here the results of paleoseismic investigations at three additional sites further to the northeast along the HFT within the Indian states of West Bengal and Assam. The three sites reside between the meizoseismal areas of the 1934 Bihar-Nepal and 1950 Assam earthquakes. The two westernmost of the sites, near the village of Chalsa and near the Nameri Tiger Preserve, show that offsets during the last surface rupture event were at minimum of about 14 m and 12 m, respectively. Limits on the ages of surface rupture at Chalsa (site A) and Nameri (site B), though broad, allow the possibility that the two sites record the same great historical rupture reported in Nepal around A.D. 1100. The correlation between the two sites is supported by the observation that the large displacements as recorded at Chalsa and Nameri would most likely be associated with rupture lengths of hundreds of kilometers or more and are on the same order as reported for a surface rupture earthquake reported in Nepal around A.D. 1100. Assuming the offsets observed at Chalsa and Nameri occurred synchronously with reported offsets in Nepal, the rupture length of the event would approach 700 to 800 km. The easternmost site is located within Harmutty Tea Estate (site C) at the edges of the 1950 Assam earthquake meizoseismal area. Here the most recent event offset is relatively much smaller (<2.5 m), and radiocarbon dating shows it to have occurred after A.D. 1100 (after about A.D. 1270). The location of the site near the edge of the meizoseismal region of the 1950 Assam earthquake and the relatively lesser offset allows speculation that the displacement records the 1950 M-w 8.4 Assam earthquake. Scatter in radiocarbon ages on detrital charcoal has not resulted in a firm bracket on the timing of events observed in the trenches. Nonetheless, the observations collected here, when taken together, suggest that the largest of thrust earthquakes along the Himalayan arc have rupture lengths and displacements of similar scale to the largest that have occurred historically along the world's subduction zones.

Physics with e(+)e(-) linear colliders

The physics potential of e(+) e(-) linear colliders is summarized in this report. These machines are planned to operate in the first phase at a center-of-mass energy of 500 GeV, before being scaled up to about 1 TeV. In the second phase of the operation, a final energy of about 2 TeV is expected. The machines will allow us to perform precision tests of the heavy particles in the Standard Model, the top quark and the electroweak bosons. They are ideal facilities for exploring the properties of Higgs particles, in particular in the intermediate mass range. New vector bosons and novel matter particles in extended gauge theories can be searched for and studied thoroughly. The machines provide unique opportunities for the discovery of particles in supersymmetric extensions of the Standard Model, the spectrum of Higgs particles, the supersymmetric partners of the electroweak gauge and Higgs bosons, and of the matter particles. High precision analyses of their properties and interactions will allow for extrapolations to energy scales close to the Planck scale where gravity becomes significant. In alternative scenarios, i.e. compositeness models, novel matter particles and interactions can be discovered and investigated in the energy range above the existing colliders lip to the TeV scale. Whatever scenario is realized in Nature, the discovery potential of e(+) e(-) linear colliders and the high precision with which the properties of particles and their interactions can be analyzed, define an exciting physics program complementary to hadron machines. (C) 1998 Elsevier Science B.V. All rights reserved.

Precise measurement of hyperfine intervals using avoided crossing of dressed states

We demonstrate a technique for precisely measuring hyperfine intervals in alkali atoms. The atoms form a three-level system in the presence of a strong control laser and a weak probe laser. The dressed states created by the control laser show significant linewidth reduction. We have developed a technique for Doppler-free spectroscopy that enables the separation between the dressed states to be measured with high accuracy even in room temperature atoms. The states go through an avoided crossing as the detuning of the control laser is changed from positive to negative. By studying the separation as a function of detuning, the center of the level-crossing diagram is determined with high precision, which yields the hyperfine interval. Using room temperature Rb vapor, we obtain a precision of 44 kHz. This is a significant improvement over the current precision of similar to1 MHz.

Strip based coding for large images using wavelets

Thanks to advances in sensor technology, today we have many applications (space-borne imaging, medical imaging, etc.) where images of large sizes are generated. Straightforward application of wavelet techniques for above images involves certain difficulties. Embedded coders such as EZW and SPIHT require that the wavelet transform of the full image be buffered for coding. Since the transform coefficients also require storing in high precision, buffering requirements for large images become prohibitively high. In this paper, we first devise a technique for embedded coding of large images using zero trees with reduced memory requirements. A 'strip buffer' capable of holding few lines of wavelet coefficients from all the subbands belonging to the same spatial location is employed. A pipeline architecure for a line implementation of above technique is then proposed. Further, an efficient algorithm to extract an encoded bitstream corresponding to a region of interest in the image has also been developed. Finally, the paper describes a strip based non-embedded coding which uses a single pass algorithm. This is to handle high-input data rates. (C) 2002 Elsevier Science B.V. All rights reserved.

The standard enthalpy and entropy of formation of Rh2O3 - A third-law optimization

The standard Gibbs energy of formation of Rh203 at high temperature has been determined recently with high precision. The new data are significantly different from those given in thermodynamic compilations.Accurate values for enthalpy and entropy of formation at 298.15 K could not be evaluated from the new data,because reliable values for heat capacity of Rh2O3 were not available. In this article, a new measurement of the high temperature heat capacity of Rh2O3 using differential scanning calorimetry (DSC) is presented.The new values for heat capacity also differ significantly from those given in compilations. The information on heat capacity is coupled with standard Gibbs energy of formation to evaluate values for standard enthalpy and entropy of formation at 289.15 K using a multivariate analysis. The results suggest a major revision in thermodynamic data for Rh2O3. For example, it is recommended that the standard entropy of Rh203 at 298.15 K be changed from 106.27 J mol-' K-'given in the compilations of Barin and Knacke et al. to 75.69 J mol-' K". The recommended revision in the standard enthalpy of formation is from -355.64 kJ mol-'to -405.53 kJ mol".

Refinement of thermodynamic properties of ReO2

The standard Gibbs energy of formation of ReO2 in the temperature range from 900 to 1200 K has been determined with high precision using a novel apparatus incorporating a buffer electrode between reference and working electrodes. The role of the buffer electrode was to absorb the electrochemical flux of oxygen through the solid electrolyte from the electrode with higher oxygen chemical potential to the electrode with lower oxygen potential. It prevented the polarization of the measuring electrode and ensured accurate data. The Re+ReO2 working electrode was placed in a closed stabilized-zirconia crucible to prevent continuous vaporization of Re2O7 at high temperatures. The standard Gibbs energy of the formation of ReO2 can be represented by the equation View the MathML source Accurate values of low and high temperature heat capacity of ReO2 are available in the literature. The thermal data are coupled with the standard Gibbs energy of formation, obtained in this study, to evaluate the standard enthalpy of formation of ReO2 at 298.15 K by the ‘third law’ method. The value of standard enthalpy of formation at 298.15 K is: View the MathML source(ReO2)/kJ mol−1=−445.1 (±0.2). The uncertainty estimate includes both random (2σ) and systematic errors.

Tip Motion Control and Scanning of a Reorientable Micromanipulator With Axially Located Tip

Two-axis micromanipulators, whose tip orientation and position can be controlled in real time in the scanning plane, enable versatile probing systems for 2.5-D nanometrology. The key to achieve high-precision probing systems is to accurately control the interaction point of the manipulator tip when its orientation is changed. This paper presents the development of a probing system wherein the deviation in the end point due to large orientation changes is controlled to within 10 nm. To achieve this, a novel micromanipulator design is first proposed, wherein the end point of the tip is located on the axis of rotation. Next, the residual tip motion caused by fabrication error and actuation crosstalk is modeled and a systematic method to compensate it is presented. The manipulator is fabricated and the performance of the developed scheme to control tip position during orientation change is experimentally validated. Subsequently, the two-axis probing system is demonstrated to scan the full top surface of a micropipette down to a diameter of 300 nm.

Reconstructing the properties of dark energy using standard sirens

Future space-based gravity wave (GW) experiments such as the Big Bang Observatory (BBO), with their excellent projected, one sigma angular resolution, will measure the luminosity distance to a large number of GW sources to high precision, and the redshift of the single galaxies in the narrow solid angles towards the sources will provide the redshifts of the gravity wave sources. One sigma BBO beams contain the actual source in only 68% of the cases; the beams that do not contain the source may contain a spurious single galaxy, leading to misidentification. To increase the probability of the source falling within the beam, larger beams have to be considered, decreasing the chances of finding single galaxies in the beams. Saini et al. T.D. Saini, S.K. Sethi, and V. Sahni, Phys. Rev. D 81, 103009 (2010)] argued, largely analytically, that identifying even a small number of GW source galaxies furnishes a rough distance-redshift relation, which could be used to further resolve sources that have multiple objects in the angular beam. In this work we further develop this idea by introducing a self-calibrating iterative scheme which works in conjunction with Monte Carlo simulations to determine the luminosity distance to GW sources with progressively greater accuracy. This iterative scheme allows one to determine the equation of state of dark energy to within an accuracy of a few percent for a gravity wave experiment possessing a beam width an order of magnitude larger than BBO (and therefore having a far poorer angular resolution). This is achieved with no prior information about the nature of dark energy from other data sets such as type Ia supernovae, baryon acoustic oscillations, cosmic microwave background, etc. DOI:10.1103/PhysRevD.87.083001

Position control of DC motors with experience mapping based prediction controller

The paper presents a new controller inspired by the human experience based, voluntary body action control (dubbed motor control) learning mechanism. The controller is called Experience Mapping based Prediction Controller (EMPC). EMPC is designed with auto-learning features without the need for the plant model. The core of the controller is formed around the motor action prediction-control mechanism of humans based on past experiential learning with the ability to adapt to environmental changes intelligently. EMPC is utilized for high precision position control of DC motors. The simulation results are presented to show that accurate position control is achieved using EMPC for step and dynamic demands. The performance of EMPC is compared with conventional PD controller and MRAC based position controller under different system conditions. Position Control using EMPC is practically implemented and the results are presented.

Probing the indefinite CP nature of the Higgs boson through decay distributions in the process e(+)e(-) -> t(t)over-bar Phi

The recently discovered scalar resonance at the Large Hadron Collider is now almost confirmed to be a Higgs boson, whose CP properties are yet to be established. At the International Linear Collider with and without polarized beams, it may be possible to probe these properties at high precision. In this work, we study the possibility of probing departures from the pure CP-even case, by using the decay distributions in the process e(+)e(-) -> t (t) over bar Phi, with Phi mainly decaying into a b (b) over bar pair. We have compared the case of a minimal extension of the Standard Model case (model I) with an additional pseudoscalar degree of freedom, with a more realistic case namely the CP-violating two-Higgs doublet model (model II) that permits a more general description of the couplings. We have considered the International Linear Collider with root s = 800 GeV and integrated luminosity of 300 fb(-1). Our main findings are that even in the case of small departures from the CP-even case, the decay distributions are sensitive to the presence of a CP-odd component in model II, while it is difficult to probe these departures in model I unless the pseudoscalar component is very large. Noting that the proposed degrees of beam polarization increase the statistics, the process demonstrates the effective role of beam polarization in studies beyond the Standard Model. Further, our study shows that an indefinite CP Higgs would be a sensitive laboratory to physics beyond the Standard Model.

Parametrisation-free determination of the shape parameters for the pion electromagnetic form factor

Recent data from high-statistics experiments that have measured the modulus of the pion electromagnetic form factor from threshold to relatively high energies are used as input in a suitable mathematical framework of analytic continuation to find stringent constraints on the shape parameters of the form factor at t = 0. The method uses also as input a precise description of the phase of the form factor in the elastic region based on Fermi-Watson theorem and the analysis of the pi pi scattering amplitude with dispersive Roy equations, and some information on the spacelike region coming from recent high precision experiments. Our analysis confirms the inconsistencies of several data on the modulus, especially from low energies, with analyticity and the input phase, noted in our earlier work. Using the data on the modulus from energies above 0.65 GeV, we obtain, with no specific parametrisation, the prediction < r(pi)(2)> is an element of (0.42, 0.44) fm(2) for the charge radius. The same formalism leads also to very narrow allowed ranges for the higher-order shape parameters at t = 0, with a strong correlation among them.

Constraints on Be-10 and Ca-41 distribution in the early solar system from Al-26 and Be-10 studies of Efremovka CAIs

Three refractory coarse grained CAIs from the Efremovka CV3 chondrite, one (E65) previously shown to have formed with live Ca-41, were studied by ion microprobe for their Al-26-Mg-26 and Be-10-B-10 systematic in order to better understand the origin of Be-10. The high precision Al-Mg data and the inferred Al-26/Al-27 values attest that the precursors of the three CAIs evolved in the solar nebula over a period of few hundred thousand years before last melting-crystallization events. The initial Be-10/Be-9 ratios and delta B-10 values defined by the Be-10 isochrons for the three Efremovka CAIs are similar within errors. The CAI Be-10 abundance in published data underscores the large range for initial Be-10/Be-9 ratios. This is contrary to the relatively small range of Al-26/Al-27 variations in CAIs around the canonical ratio. Two models that could explain the origin of this large Be-10/Be-9 range are assessed from the collateral variations predicted for the initial delta B-10 values: (i) closed system decay of Be-10 from a ``canonical'' Be-10/Be-9 ratio and (ii) formation of CAIs from a mixture of solid precursors and nebula gas irradiated during up to a few hundred thousand years. The second scenario is shown to be the most consistent with the data. This shows that the major fraction of Be-10 in CAIs was produced by irradiation of refractory grains, while contributions of galactic cosmic rays trapping and early solar wind irradiation are less dominant. The case for Be-10 production by solar cosmic rays irradiation of solid refractory precursors poses a conundrum for Ca-41 because the latter is easily produced by irradiation and should be more abundant than what is observed in CAIs. Be-10 production by irradiation from solar energetic particles requires high Ca-41 abundance in early solar system, however, this is not observed in CAIs. (C) 2013 Elsevier B.V. All rights reserved.