The effect of heat treatment time on the formation of forsterite (Mg2SiO4)

In this work, phase pure forsterite (Mg2SiO4) powder was synthesized via solid-state method and heat treatment stage. X-ray diffraction analysis was conducted to investigate on the phase purity of forsterite powder. The synthesized powder were heat treated at 1200 oC for 1 min, 1 hour and 2 hours with ramping rate of 10 oC/min. Decomposition was observed for powder heat treated for 1 min. Periclase and enstatite peak were detected as a form of secondary phases. 1 and 2 hours of holding during heat treatment produced phase pure forsterite with a difference of improved intensity which indicated that there was enhancement towards the crystalline structure of forsterite powder. SEM micrograph was carried out to show the morphology of the obtained forsterite powder. The powders are agglomerated with various sizes was observed.

Trans-ancestry genome-wide association study identifies 12 genetic loci influencing blood pressure and implicates a role for DNA methylation

We carried out a trans-ancestry genome-wide association and replication study of blood pressure phenotypes among up to 320,251 individuals of East Asian, European and South Asian ancestry. We find genetic variants at 12 new loci to be associated with blood pressure (P = 3.9 × 10-11 to 5.0 × 10-21). The sentinel blood pressure SNPs are enriched for association with DNA methylation at multiple nearby CpG sites, suggesting that, at some of the loci identified, DNA methylation may lie on the regulatory pathway linking sequence variation to blood pressure. The sentinel SNPs at the 12 new loci point to genes involved in vascular smooth muscle (IGFBP3, KCNK3, PDE3A and PRDM6) and renal (ARHGAP24, OSR1, SLC22A7 and TBX2) function. The new and known genetic variants predict increased left ventricular mass, circulating levels of NT-proBNP, and cardiovascular and all-cause mortality (P = 0.04 to 8.6 × 10-6). Our results provide new evidence for the role of DNA methylation in blood pressure regulation

Facile sonochemical synthesis of N,Cl-codoped TiO2: Synthesis effects, mechanism and photocatalytic performance

In this study, both nitrogen and chlorine were successfully doped into TiO2(N,Cl-codoped TiO2) via a sonochemical method using titanium(IV) butoxide and ammonium chloride as precursors. When N,Cl-codoped TiO2was tested on the decolorization of CI Reactive Black 5 (RB5), it was observed that the photocatalytic activity exhibited by the synthesized photocatalyst was greatly affected by the synthesis conditions. Increasing the sonication intensity or duration up to a certain point shifted the absorption onset toward a lower energy and improved the crystallinity of the synthesized photocatalyst. It was also observed that increasing the N,Cl:Ti molar ratio to 2 significantly enhanced the photocatalytic activity of N,Cl-codoped TiO2, but higher molar ratios inhibited the decolorization of RB5. A relatively low calcination temperature of 200°C was sufficient to further improve the photocatalytic activity of N,Cl-codoped TiO2. The following recommended synthesis conditions successfully yielded 96.02% RB5 decolorization under visible light irradiation for 5h: sonication amplitude of 40%, sonication duration of 3.62h, N,Cl:Ti molar ratio of 2 and calcination temperature of 200°C. The decolorization rate constant of N,Cl-codoped TiO2(0.01min-1) was also significantly higher than that of commercially available P25 (0.0055min-1)

Temporary cardiopulmonary bypass and isolated lung ventilation for tracheal stenosis and reconstruction.

A 27-yr-old lady with a past history of prolonged ventilation presented with worsening respiratory distress caused by tracheal stenosis. She required urgent tracheal resection and reconstruction. Because of the risk of an acute respiratory obstruction, spinal anaesthesia was used to establish cardiopulmonary bypass by cannulating the femoral artery and femoral vein. Adequate gas exchange was possible with full flow rate. Thoracotomy was then carried out to mobilize the left main bronchus. After successfully securing an airway by intubation of the left main bronchus, cardiopulmonary bypass was discontinued and tracheal resection and anastomosis was done under conventional one lung anaesthesia

The effects of calcium-to-phosphorus ratio on the densification and mechanical properties of hydroxyapatite ceramic

In this work, hydroxyapatite (HA) powders were synthesized using calcium hydroxide Ca(OH)(2) and orthophosphoric acid H3PO4 via wet chemical precipitation method in aqueous medium. Calcium-to-phosphorus (Ca/P) ratio was set to 1.57, 1.67, 1.87 that yield calcium-deficient HA, stoichiometric HA, and calcium-rich HA, respectively. These synthesized HA powders (having different Ca/P ratio) were characterized in terms of particle size and microstructural examination. Then, the densification and mechanical properties of the calcium-deficient HA, stoichiometric HA, and calcium-rich HA were evaluated from 1000 to 1350 degrees C. Experimental results have shown that no decomposition of hydroxyapatite phase was observed for stoichiometric HA (Ca/P = 1.67) and calcium-deficient HA (Ca/P = 1.57) despite sintered at high temperature of 1300 degrees C. However, calcium oxide (CaO) was detected for calcium-rich HA (Ca/P = 1.87) when samples sintered at the same temperature. The study revealed that the highest mechanical properties were found in stoichiometric HA samples sintered at 1100-1150 degrees C, having relative density of similar to 99.8, Young's modulus of similar to 120 GPa, Vickers hardness of similar to 7.23 GPa, and fracture toughness of similar to 1.22 MPam(1/2

The effect of sintering ramp rate on the sinterability of forsterite ceramics

In the present work, pure forsterite (Mg2SiO4) powder was successfully synthesised via ball milling and subsequent heat treatment as an evident from X-ray diffraction analysis. The synthesised powder were formed by powder agglomerates that were made up of loosely packed fine particles. Then, the forsterite green bodies were sintered at 1200 and 1400 degrees C with two different ramp rates (2 and 10 degrees C per minute) via conventional pressureless sintering. No decomposition of forsterite phase was observed at both ramp rates. This study revealed that lower ramp rate (2 degrees C per minute) possessed minor improvement on the mechanical properties only at lower sintering temperature (1200 degrees C), whereas 10 degrees C per minute ramp rate gave a significant enhancement on the mechanical properties of forsterite at 1400 degrees C. A high fracture toughness of similar to 4.9 MPam(1/2) and Vickers hardness of similar to 7.1 GPa were obtained for forsterite samples sintered at 1400 degrees C with a ramp rate of 10 degrees C per minute

Evaluation of the performance of TaN diffusion barrier against copper diffusion using SIMS and AFM

10.1049/el:20010390Electronics Letters3710660-661ELLE

Morphological studies of randomized dispersion magnetite nanoclusters coated with silica

In this study, we report a simple way to produce randomized dispersion magnetite nanoclusters coated with silica (RDMNS) via Stöber process with minor modifications. The morphology of silica coated magnetite nanoclusters was emphasized by studying various reaction parameters including alcohols with different polarities as co-solvents, concentration of alcohol-water, concentration of alkaline catalyst (ammonia), and concentration of TEOS monomer. The results of transmission electron microscope (TEM) showed that the sizes and morphological behaviour of the magnetite nanoclusters vary accordingly with the different reaction parameters investigated. The results showed that ethanol would be the best candidate as co-solvent in the preparation of randomized dispersion magnetite nanoclusters. Besides, the optimum alcohol-water ratio has been determined to be 70-30 v/v as this concentration range could render desired shape of randomized dispersion magnetite nanoclusters. The volume of ammonia (NH 3) catalyst in the reaction media also strongly governs the formation of silica coated magnetite nanoclusters in a desired shape. Apart from that, the addition of TEOS monomer into the reaction media has to be well-controlled as the excess amount of monomer added might affect the thickness of the silica layer that is coated on the magnetite nanoparticles. Prior to silica coating, the bare magnetite nanoparticles were first treated with trisodium citrate (0.5 M) to enhance the particles' dispersibility. Improvement in the size distribution and dispersibility of the magnetite nanoparticles after the citrate treatment has been examined using TEM. The XRD results show that the magnetite samples retained good crystallinity although they have been surface-modified with citrate group and silica. The Fourier transform infrared (FT-IR) and thermogravimetric analysis (TGA) prove that the magnetite nanoparticles have been successfully coated with citrate and silica. The superparamagnetic behaviour of the magnetite samples was confirmed by VSM. The produced silica coated magnetite nanoclusters possess great potential to be applied in bio-medical research and clinical diagnosis application. © 2010 Elsevier Ltd and Techna Group S.r.l

Reaction losses of charged particles in CsI(Tl) crystals

International audienceTo efficiently detect energetic light charged particles, it is common to use arrays of energy-loss telescopes involving two or more layers of detection media. As the energy of the particles increases, thicker layers are usually needed. However, carrying out measurements with thick-telescopes may require corrections for the losses due to nuclear reactions induced by the incident particles on nuclei within the detector and for the scattering of incident particles out of the detector, without depositing their full energy in the active material. In this paper, we develop a method for measuring such corrections and determine the reaction and out-scattering losses for data measured with the silicon-CsI(Tl) telescopes of the newly developed HiRA10 array. The extracted efficiencies are in good agreement with model predictions using the GEANT4 reaction loss algorithm for Z=1 and Z=2 isotopes. After correcting for the HiRA10 geometry, we obtain a general function that describes the loss of efficiency due to reaction losses in CsI(Tl) crystals as a function of range