The influence of carbon on the microstructure of sintered alumina

Alumina is one of the most used ceramic materials, and as such understanding its sintering and densification processes is important. It is known that the sintering behavior is strongly affected by dopants, such as MgO, which promotes sintering and limits grain growth. The present study focuses on the influence of carbon on the sintering of alumina. Commercial ready-to-press (RTP) alumina specimens were sintered to full density (98%) at 1600°C for 2 h in air and in a graphite furnace using flowing He, a reducing atmosphere. The specimens sintered in graphite furnace resulted in a black color, an indication of the high carbon content originating from the large amount of organic compounds in RTP powders. In comparison, alumina specimens sintered in air, where the carbon decomposes during sintering at elevated temperatures, were white. Sintering with carbon in under He resulted in specimens with a finer microstructure. The presence of carbon retards grain growth, most probably by solute drag. A uniform segregation of carbon to the grain boundaries of alumina was shown by atom probe tomography [1]. In order to evaluate the wear resistance of the sintered alumina, the time (normalized by area) to section specimens with a diamond wafer blade was determined. The time to section specimens containing carbon was more than 40 times longer compared to the specimens sintered in air. The combination of reducing atmosphere and high carbon content has a positive effect on the microstructure and mechanical properties of alumina. [1] Marquis, E. A., Yahya, N. A., Larson, D. J., Miller, M. K. & Todd, R. I. Probing the improbable: imaging C atoms in alumina. Mater. Today 13, 34–36 (2010)

Electroweak Matrix Elements in the Two-Nucleon Sector from Lattice QCD

We demonstrate how to make rigorous predictions for electroweak matrix elements in nuclear systems directly from QCD. More precisely, we show how to determine the short-distance contributions to low-momentum transfer electroweak matrix elements in the two-nucleon sector from lattice QCD. In potential model descriptions of multi-nucleon systems, this is equivalent to uniquely determining the meson-exchange currents, while in the context of nuclear effective field theory, this translates into determining the coefficients of local, gauge-invariant, multi-nucleon-electroweak current operators. The energies of the lowest-lying states of two nucleons on a finite volume lattice with periodic boundary conditions in the presence of a background magnetic field are sufficient to determine the local four-nucleon operators that contribute to the deuteron magnetic moment and to the threshold cross-section of n + p -> d + gamma. Similarly, the energy-levels of two nucleons immersed in a background isovector axial weak field can be used to determine the coefficient of the leading local four-nucleon operator contributing to the neutral- and charged-current break-up of the deuteron. This is required for the extraction of solar neutrino fluxes at SNO and future neutrino experiments.Comment: 22 pages, 4 figure

Evidence for the Adverse Effect of Starvation on Bone Quality: A Review of the Literature

Malnutrition and starvation’s possible adverse impacts on bone health and bone quality first came into the spotlight after the horrors of the Holocaust and the ghettos of World War II. Famine and food restrictions led to a mean caloric intake of 200–800 calories a day in the ghettos and concentration camps, resulting in catabolysis and starvation of the inhabitants and prisoners. Severely increased risks of fracture, poor bone mineral density, and decreased cortical strength were noted in several case series and descriptive reports addressing the medical issues of these individuals. A severe effect of severely diminished food intake and frequently concomitant calcium- and Vitamin D deficiencies was subsequently proven in both animal models and the most common cause of starvation in developed countries is anorexia nervosa. This review attempts to summarize the literature available on the impact of the metabolic response to Starvation on overall bone health and bone quality

Pattern Specification and Immune Response Transcriptional Signatures of Pericardial and Subcutaneous Adipose Tissue

Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality in the United States. Recent studies suggest that pericardial adipose tissue (PCAT) secretes inflammatory factors that contribute to the development of CVD. To better characterize the role of PCAT in the pathogenesis of disease, we performed a large-scale unbiased analysis of the transcriptional differences between PCAT and subcutaneous adipose tissue, analysing 53 microarrays across 19 individuals. As it was unknown whether PCAT-secreted factors are produced by adipocytes or cells in the supporting stromal fraction, we also sought to identify differentially expressed genes in isolated pericardial adipocytes vs. isolated subcutaneous adipocytes. Using microarray analysis, we found that: 1) pericardial adipose tissue and isolated pericardial adipocytes both overexpress atherosclerosis-promoting chemokines and 2) pericardial and subcutaneous fat depots, as well as isolated pericardial adipocytes and subcutaneous adipocytes, express specific patterns of homeobox genes. In contrast, a core set of lipid processing genes showed no significant overlap with differentially expressed transcripts. These depot-specific homeobox signatures and transcriptional profiles strongly suggest different functional roles for the pericardial and subcutaneous adipose depots. Further characterization of these inter-depot differences should be a research priority

INVERSE SCATTERING TRANSFORM ANALYSIS OF STOKES-ANTI-STOKES STIMULATED RAMAN SCATTERING

Zakharov-Shabat--Ablowitz-Kaup-Newel-Segur representation for Stokes-anti-Stokes stimulated Raman scattering is proposed. Periodical waves, solitons and self-similarity solutions are derived. Transient and bright threshold solitons are discussed.Comment: 16 pages, LaTeX, no figure

TCT-400 2-Year Clinical Follow-up of the TRYTON IDE Randomized Trial Comparing a Dedicated Bifurcation Stent to Provisional Stenting in the Treatment of Coronary Bifurcations

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