X-ray, scanning electron microscopy and electrical properties of synthetic fresnoite (Ba2TiSi2O8) ceramics

Polycrystalline ceramic samples of fresnoite (Ba₂TiSi₂O₈ or BTS) have been prepared by a standard solid-state reaction method using high-purity oxides and carbonates. For one set of compounds, in stoichiometric ratio BaCO₃, TiO₂ and SiO₂ were melted at 1300°C and then sintered into pellet form, whereas the other set of compounds have been prepared without melting and sintered into pellet form at 1250°C. The formation of the single-phase compound and its structural parameters were investigated by X-ray diffraction followed by Rietveld refinement and scanning electron microscopic (SEM) techniques. A better agreement between the observed and calculated X-ray diffraction patterns was obtained by performing the Rietveld refinement with a structural model using the non-centrosymmetric space group P4bm. A better agreement between observed and calculated d-values shows that the lattice parameters calculated using the Rietveld refinement analysis are better than that of the earlier report so far. The activation energies of both compounds were calculated by measuring its dc electrical conductivities. The results are discussed in detail.     

New bioluminogenic substrates for monoamine oxidase assays

Novel bioluminogenic substrates were designed for probing monoamine oxidase (MAO) activity based on a simple and effective beta-elimination strategy. By modifying the amino group and the central core of luciferin derivatives, we have developed a series of substrates useful for assays of MAO A or B, or both. One of these substrates, exhibiting low Km values and high signal-to-background ratios with both isozymes, was shown to accurately measure the Ki values of known MAO inhibitors. This substrate is a key component in the development of a highly sensitive homogeneous MAO assay for high-throughput screening (HTS) of compounds in drug discovery and for monitoring MAO activity in complex biological systems. This design strategy should be applicable to fluorogenic MAO substrates and could broaden the structural requirements of substrates for other enzyme assays.     

Impact of Photodynamic Treatment with Meso-substituted Porphyrin on the Immunomodulatory Capacity of White Blood Cell-containing Red Blood Cell Products

After transfusion, the presence of contaminating white blood cells (WBC) in blood components may result in either deleterious or positive immunological responses. We have previously reported that photodynamic treatment (PDT) with meso-substituted mono-phenyl-tri-( N -methyl-4-pyridyl)-porphyrin (Tri-P(4)) and red light can inactivate pathogens in red blood cell (RBC) products. The present study explored the effect of PDT on contaminating WBC in RBC products with varying hematocrit (Hct). After PDT, we evaluated adaptive and innate immunomodulation through allogeneic and mitogenic stimulation. PDT resulted in decreased T-cell proliferation which was more pronounced with lower Hct. Dark effect of porphyrin Tri-P(4) was remarkable on antigen-presenting cells affecting expression of co-stimulatory molecules CD80/CD86. Finally, cytokine profile after PDT revealed a mixed Th1/Th2 type response while surface antigen expression supported the development of alternatively activated macrophages (AAMφ or Type 2 macrophages) instead of dendritic cells. In conclusion, PDT with Tri-P(4) altered proliferation, allo-stimulation, cell surface antigen expression and cytokine profiles of the cells. These results suggest that PDT may be potentially useful in preventing transfusion-associated graft- versus -host disease and alloimmunization. It seems worthwhile to further explore PDT-induced immunomodulation to optimize conditions which may result in allo-tolerance by AAMφ.     

Preparation of Nd:Y3Al5O12 nanocrystals by low temperature glycol route

Y₃Al₅O₁₂, yttrium aluminum garnet (YAG) single crystals are extensively used as host materials for solid‐state lasers. The materials in nano sizes are of immense importance due to their fascinating physical and chemical properties. Nanocrystals of Nd doped YAG were synthesized by low temperature glycol route. This method consists of a mixing of nitrates in an aqueous media at reasonably low temperatures. The Nd doping concentration was optimized and kept at 2 mol%. The prepared material was annealed at different temperatures. Single phase Nd:YAG nanocrystals were obtained at 850 °C. The prepared nanocrystals were characterized by XRD, SEM and TEM techniques for the crystalline phase, crystalline size and structure. The crystalline sizes were obtained in the range of ∼20–30 nm. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Principled sure independence screening for Cox models with ultra-high-dimensional covariates

It is rather challenging for current variable selectors to handle situations where the number of covariates under consideration is ultra-high. Consider a motivating clinical trial of the drug bortezomib for the treatment of multiple myeloma, where overall survival and expression levels of 44760 probesets were measured for each of 80 patients with the goal of identifying genes that predict survival after treatment. This dataset defies analysis even with regularized regression. Some remedies have been proposed for the linear model and for generalized linear models, but there are few solutions in the survival setting and, to our knowledge, no theoretical support. Furthermore, existing strategies often involve tuning parameters that are difficult to interpret. In this paper we propose and theoretically justify a principled method for reducing dimensionality in the analysis of censored data by selecting only the important covariates. Our procedure involves a tuning parameter that has a simple interpretation as the desired false positive rate of this selection. We present simulation results and apply the proposed procedure to analyze the aforementioned myeloma study.     

The Tersoff potential for phonons in GaAs

We report on the use of the Tersoff empirical potential applied to GaAs. Cohesive and elastic properties, as well as phonon frequencies and Grüneisen parameters at the Γ and X points, are calculated and compared to experimental data. The limitations of the potential and its existing parametrisations are discussed.     

Gravitational and Electroweak Unification

Einstein suggested that a unified field theorybe constructed by replacing the diffeomorphisms (thecoordinate transformations of general relativity) withsome larger group. We have constructed a theory that unifies the gravitational and electroweakfields by replacing the diffeomorphisms with the largestgroup of coordinate transformations under whichconservation laws are covariant statements. Thisreplacement leads to a theory with field equations whichimply the validity of the Einstein equations of generalrelativity, with a stress-energy tensor that is justwhat one expects for the electroweak field andassociated currents. The electroweak field appears as aconsequence of the field equations (rather than as a"compensating field" introduced to secure gaugeinvariance). There is no need for symmetry breaking toaccommodate mass, because the U(1) × SU(2) gaugesymmetry is approximate from the outset. Thegravitational field is described by the space-timemetric, as in general relativity. The electroweak fieldis described by the "mixed symmetry" part of the Riccirotation coefficients. The gauge symmetry-breakingquantity is a vector formed by contracting theLevi-Civita symbol with the totally antisymmetric partof the Ricci rotation coefficients.     

Growth of molybdenum disulphide using iodine as transport material

In the present paper an attempt has been made to describe the chemical vapor transport (CVT) technique used for the growth of molybdenum disulphide (MoS₂) single crystals. Iodine (I₂) is used as transporting material for this purpose. The energy dispersive analysis by X-ray (EDAX) confirmed the stoichiometry of the as-grown crystals. The lattice parameters of these crystals were determined from the X-ray diffraction analysis. The grown crystals were examined under the optical zoom microscope for their surface microstructure study.