Determination of the thermodynamic stability of TiB2

The standard free energy of formation of titanium boride (TiB2) Was measured by the Electro Motive Force (EMF) method (by using yttria doped thoria (YDT) as the solid electrolyte). Two galvanic cells viz. Cell (I): Pt, TiB2 (s), TiO2 (s), B (s) vertical bar YDT vertical bar NiO (s), Ni (s), Pt and cell (II): Pt, TiB2 (s), TiO2 (s), B (s) vertical bar YDT vertical bar FeO (s). Fe (s), Pt were constructed in order to determine the Delta(f)G degrees, of TiB2. Enthalpy increments on TiB2 were measured by using inverse drop calorimetry over the temperature range 583-1769 K. The heat capacity, entropy and the free energy function have been derived from these experimental data in the temperature range 298-1800 K. The mean value of the standard enthalpy of formation of TiB2 (Delta H-f(298)degrees (TiB2)) was obtained by combining these Delta(f)G degrees, values and the free energy functions of TiB2 derived from the drop calorimetry data. The mean values of Delta H-f(298)degrees (TiB2) derived from the Delta(f)G degrees, data obtained from cell I and II were -322 +/- 1.2 kJ mol(-1) and -323.3 +/- 2.1 kJ mol(-1), respectively. These values were found to be in very good agreement with the assessed data. (C) 2009 Elsevier B.V. All rights reserved.

Identification and thermodynamic characterization of molten globule states of periplasmic binding proteins

Molten globule-like intermediates have been shown to occur during protein folding and are thought to be involved in protein translocation and membrane insertion. However, the determinants of molten globule stability and the extent of specific packing in molten globules is currently unclear. Using far- and near-UV CD and intrinsic and ANS fluorescence, we show that four periplasmic binding proteins (LBP, LIVBP, MBP, and RBP) form molten globules at acidic pH values ranging from 3.0 to 3.4. Only two of these (LBP and LIVBP) have similar sequences, but all four proteins adopt similar three-dimensional structures. We found that each of the four molten globules binds to its corresponding ligand without conversion to the native state. Ligand binding affinity measured by isothermal titration calorimetry for the molten globule state of LIVBP was found to be comparable to that of the corresponding native state, whereas for LBP, MBP, and RBP, the molten globules bound ligand with approximately 5-30-fold lower affinity than the corresponding native states. All four molten globule states exhibited cooperative thermal unfolding assayed by DSC. Estimated values of Delta C-p of unfolding show that these molten globule states contain 28-67% of buried surface area relative to the native states. The data suggest that molten globules of these periplasmic binding proteins retain a considerable degree of long range order. The ability of these sequentially unrelated proteins to form highly ordered molten globules may be related to their large size as well as an intrinsic property of periplasmic binding protein folds.

Workers are doing it for themselves? Local labor solidarity in precarious times

Historically, organized labor has played a fundamental role in guaranteeing basic rights and privileges for screen media workers and defending union and guild members (however unevenly) from egregious abuses of power. Yet, despite the recent turn to labor in media and cultural studies, organized labor today has received only scant attention, even less so in locations outside Hollywood. This presentation thus intervenes in two significant ways: first, it acknowledges the ongoing global ‘undoing’ of organized labor as a consequence of footloose production and conglomeration within the screen industries, and second, it examines a case example of worker solidarity and political praxis taking shape outside formal labor institutions in response to those structural shifts. Accordingly, it links an empirical study of individual agency to broader debates associated with the spatial dynamics of screen media production, including local capacity, regional competition, and precariousness. Drawing from ethnographic interviews with local film and television workers in Glasgow, Scotland, I consider the political alliance among three nascent labor organizations in the city: one for below-the-line crew, one for facility operators, and (oddly enough) one for producers. Collectively, the groups share a desire to transform Glasgow into a global production hub, following the infrastructure developments in nearby cities like Belfast, Prague, and Budapest. They furthermore frame their objectives in political terms: establishing global scale is considered a necessary maneuver to improve local working conditions like workplace safety, income disparity, skills training, and job access. Ultimately, I argue these groups are a product of an inadequate union structure and outdated policy vision for the screen sector , once-supportive institutions currently out of sync with the global realities of media production. Furthermore, the groups’ advocacy efforts reveal the extent to which workers themselves (in additional to capital) can seek “spatial fixes” to suture their prospects to specific political and economic goals. Of course, such activities manifest under conditions outside of the workers’ control but nevertheless point to an important tension within capitalist social relations, namely that the agency to reshape the spatial relationships in their own lives recasts the geography of labor in terms that aren’t inherent or exclusive to the interests of global capital.

Investigation of the local Fe magnetic moments at the grain boundaries of the Ca2FeReO6 double perovskite

The local Fe ferromagnetic (FM) moment at the grain boundaries of a ceramic sample of Ca2FeReO6 double perovskite was investigated by means of x-ray magnetic circular dichroism spectroscopy at the Fe L-2,L-3 edges and compared to the overall bulk magnetization. We found that, at the grain boundaries, the Fe FM moments at H=5 T are much smaller than expected and that the MxH curve is harder than in the bulk magnetization. These results suggest a larger degree of Fe/Re antisite disorder at the grain boundaries of this sample, shedding light into the intriguing nonmetallic resistivity behavior despite the reported presence of free carriers. (c) 2007 American Institute of Physics.

Direct bone marrow HSC transplantation enhances local engraftment at the expense of systemic engraftment in NSG mice

Direct bone marrow (BM) injection has been proposed as a strategy to bypass homing inefficiencies associated with intravenous (IV) hematopoietic stem cell (HSC) transplantation. Despite physical delivery into the BM cavity, many donor cells are rapidly redistributed by vascular perfusion, perhaps compromising efficacy. Anchoring donor cells to 3-dimensional (3D) multicellular spheroids, formed from mesenchymal stem/stromal cells (MSC) might improve direct BM transplantation. To test this hypothesis, relevant combinations of human umbilical cord blood-derived CD34(+) cells and BM-derived MSC were transplanted into NOD/SCID gamma (NSG) mice using either IV or intrafemoral (IF) routes. IF transplantation resulted in higher human CD45(+) and CD34(+) cell engraftment within injected femurs relative to distal femurs regardless of cell combination, but did not improve overall CD45(+) engraftment at 8 weeks. Analysis within individual mice revealed that despite engraftment reaching near saturation within the injected femur, engraftment at distal hematopoietic sites including peripheral blood, spleen and non-injected femur, could be poor. Our data suggest that the retention of human HSC within the BM following direct BM injection enhances local chimerism at the expense of systemic chimerism in this xenogeneic model.

Nash equilibrium based semantic cache in mobile sensor grid database systems

Mobile applications are being increasingly deployed on a massive scale in various mobile sensor grid database systems. With limited resources from the mobile devices, how to process the huge number of queries from mobile users with distributed sensor grid databases becomes a critical problem for such mobile systems. While the fundamental semantic cache technique has been investigated for query optimization in sensor grid database systems, the problem is still difficult due to the fact that more realistic multi-dimensional constraints have not been considered in existing methods. To solve the problem, a new semantic cache scheme is presented in this paper for location-dependent data queries in distributed sensor grid database systems. It considers multi-dimensional constraints or factors in a unified cost model architecture, determines the parameters of the cost model in the scheme by using the concept of Nash equilibrium from game theory, and makes semantic cache decisions from the established cost model. The scenarios of three factors of semantic, time and locations are investigated as special cases, which improve existing methods. Experiments are conducted to demonstrate the semantic cache scheme presented in this paper for distributed sensor grid database systems.

Manifestation of geometric frustration on magnetic and thermodynamic properties of the pyrochlores Sm2X2O7 (X=Ti,Zr)

We present here magnetization, specific heat, and Raman studies on single-crystalline specimens of the first pyrochlore member Sm2Ti2O7 of the rare-earth titanate series. Its analogous compound Sm2Zr2O7 in the rare-earth zirconate series is also investigated in the polycrystalline form. The Sm spins in Sm2Ti2O7 remain unordered down to at least T=0.5 K. The absence of magnetic ordering is attributed to very small values of exchange (θcw∼−0.26 K) and dipolar interaction (μeff∼0.15 μB) between the Sm3+ spins in this pyrochlore. In contrast, the pyrochlore Sm2Zr2O7 is characterized by a relatively large value of Sm-Sm spin exchange (θcw∼−10 K); however, long-range ordering of the Sm3+ spins is not established at least down to T=0.67 K due to frustration of the Sm3+ spins on the pyrochlore lattice. The ground state of Sm3+ ions in both pyrochlores is a well-isolated Kramers doublet. The higher-lying crystal field excitations are observed in the low-frequency region of the Raman spectra of the two compounds recorded at T=10 K. At higher temperatures, the magnetic susceptibility of Sm2Ti2O7 shows a broad maximum at T=140 K, while that of Sm2Zr2O7 changes monotonically. Whereas Sm2Ti2O7 is a promising candidate for investigating spin fluctuations on a frustrated lattice, as indicated by our data, the properties of Sm2Zr2O7 seem to conform to a conventional scenario where geometrical frustration of the spin excludes their long-range ordering.

Consumer’s comparison between local and imported organic products: A hedonic analysis of the Japanese table wine market

Although hundreds of thousands of organic products are traded on a daily basis, it is less known how imported organic products are evaluated by consumers in an importing country. The paper analyzes Japanese wine point of sale (POS) data to examine whether consumers differentiate between local and imported organic products. The results of our hedonic analyses show that the premium for imported organic red (white) wines is about 42.996 % (8.872 %) while that for domestic red (white) organic wines is about 6.440 % (1.214 %), implying that Japanese consumers pay higher premiums for imported organic agricultural products than for those produced in Japan.

Phase Diagram for the System RuO2-TiO2 in Air

There are conflicting reports in the literature regarding solid solubility in the system RuO2-TiO2. To resolve this issue a few experiments were conducted in air at 1673, 1723, and 1773 K. The results show limited terminal solid solubility. There is an extended solid-state miscibility gap that intersects the decomposition curve for the RuO2-rich solid solution generating a peritectoid reaction at 1698 K. The measured equilibrium compositions of the solid solutions are used to develop a thermodynamic description of the oxide solid solution with rutile structure. Using the subregular solution model, the enthalpy of mixing can be represented by the expression, Delta H-M/J center dot mol(-1) = XTiO2XRuO2 ( 34,100X(TiO2) + 30,750X(RuO2)). The binodal and spinodal curves and T-X phase diagram in air are computed using this datum and Gibbs energy of formation of RuO2 available in the literature. The computed results suggest that equilibrium was not attained during solubility measurements at lower temperatures reported in the literature.

Thermodynamic Properties and Phase Diagram for the System MoO2–TiO2

The activity of molybdenum dioxide (MoO2) in the MoO2–TiO2 solid solutions was measured at 1600 K using a solid-state cell incorporating yttria-doped thoria as the electrolyte. For two compositions, the emf was also measured as a function of temperature. The cell was designed such that the emf is directly related to the activity of MoO2 in the solid solution. The results show monotonic variation of activity with composition, suggesting a complete range of solid solutions between the end members and the occurrence of MoO2 with a tetragonal structure at 1600 K. A large positive deviation from Raoult's law was found. Excess Gibbs energy of mixing is an asymmetric function of composition and can be represented by the subregular solution model of Hardy as follows.The temperature dependence of the emf for two compositions is reasonably consistent with ideal entropy of mixing. A miscibility gap is indicated at a lower temperature with the critical point characterized by Tc (K)=1560 and . Recent studies indicate that MoO2 undergoes a transition from a monoclinic to tetragonal structure at 1533 K with a transition entropy of 9.91 J·(mol·K)−1. The solid solubility of TiO2 with rutile structure in MoO2 with a monoclinic structure is negligible. These features give rise to a eutectoid reaction at 1412 K. The topology of the computed phase diagram differs significantly from that suggested by Pejryd.

Thermodynamic activities in the Pb(Zr1-XTiX)O-3 solid solution at 1373 K

Although Pb(Zr1-XTiX)O-3 solid solution is the cornerstone of the piezoelectric ceramics, there is no information in the literature on thermodynamic activities of the component phases in the solid solution. Using inter-crystalline ion exchange equilibria between Pb(Zr1-XTiX)O-3 solid solution with cubic perovskite structure and (Zr1-YTiY)O-2 solid solutions with monoclinic and tetragonal structures, activities of PbTiO3 and PbZrO3 in the perovskite solid solution have been derived at 1373 K using the modified Gibbs-Duhem integration technique of Jacob and Jeffes. Tie-lines from the cubic solid solution are skewed towards the ZrO2 corner. Activities in the zirconia-rich (Zr1-YTiY)02 solid solutions are taken from a recent emf study. The results for the perovskite solid solution at 1373 K can be represented by a sub-regular solution model: Delta G(E.M) (J mol(-1)) = X-PbTiO3 X-PbZrO3(5280X(PbTiO3) - 1980X(PbZrO3)) where Delta G(E.M) is the excess Gibbs energy of mixing of the cubic solid solution and Xi represents the mole fraction of component i. There is a significant positive deviation from ideality for PbTiO3-rich compositions and mild negative deviation near the PbZrO3 corner. The cubic solid solution is intrinsically stable against composition fluctuations at temperatures down to 840 K. The results contrast sharply with the recent calorimetric data on enthalpy of mixing which signal instability of the cubic perovskite solid solution. (C) 2007 Elsevier B.V. All rights reserved.

Local numerical modelling of magnetoconvection and turbulence - implications for mean-field theories

During the last decades mean-field models, in which large-scale magnetic fields and differential rotation arise due to the interaction of rotation and small-scale turbulence, have been enormously successful in reproducing many of the observed features of the Sun. In the meantime, new observational techniques, most prominently helioseismology, have yielded invaluable information about the interior of the Sun. This new information, however, imposes strict conditions on mean-field models. Moreover, most of the present mean-field models depend on knowledge of the small-scale turbulent effects that give rise to the large-scale phenomena. In many mean-field models these effects are prescribed in ad hoc fashion due to the lack of this knowledge. With large enough computers it would be possible to solve the MHD equations numerically under stellar conditions. However, the problem is too large by several orders of magnitude for the present day and any foreseeable computers. In our view, a combination of mean-field modelling and local 3D calculations is a more fruitful approach. The large-scale structures are well described by global mean-field models, provided that the small-scale turbulent effects are adequately parameterized. The latter can be achieved by performing local calculations which allow a much higher spatial resolution than what can be achieved in direct global calculations. In the present dissertation three aspects of mean-field theories and models of stars are studied. Firstly, the basic assumptions of different mean-field theories are tested with calculations of isotropic turbulence and hydrodynamic, as well as magnetohydrodynamic, convection. Secondly, even if the mean-field theory is unable to give the required transport coefficients from first principles, it is in some cases possible to compute these coefficients from 3D numerical models in a parameter range that can be considered to describe the main physical effects in an adequately realistic manner. In the present study, the Reynolds stresses and turbulent heat transport, responsible for the generation of differential rotation, were determined along the mixing length relations describing convection in stellar structure models. Furthermore, the alpha-effect and magnetic pumping due to turbulent convection in the rapid rotation regime were studied. The third area of the present study is to apply the local results in mean-field models, which task we start to undertake by applying the results concerning the alpha-effect and turbulent pumping in mean-field models describing the solar dynamo.