Effect of sintering atmosphere on the pore-structure stability of cerium-doped nanostructured alumina

Pore-structure stability of pure and Ce-doped alumina in air and argon atmospheres was studied using DTA, TGA, N2 ads./des. and XRD with a view to understand the importance of the ionic size of the dopant cation on the pore-structure stability of alumina. The ionic size effect was studied by heat treating the Ce-alumina system in both oxidizing and reducing atmospheres to have Ce4+ (87 pm) and Ce3+ (106 pm) respectively. No compound formation between Ce and alumina was observed. In the case of pure alumina there is a drastic reduction in porosity during the transformation to α-alumina. Ce-doped alumina has a higher DSC transformation temperature corresponding to the α-alumina transformation compared to pure alumina. Ce-doped alumina showed higher pore-structure stability compared with pure alumina and the stability was relatively higher in reducing atmosphere (higher Ce3+/Ce4+ ratio, higher effective ionic size) compared with oxidizing conditions (lower Ce3+/Ce4+ ratio, lower effective ionic size)

Amine impregnated porous silica gel sorbents synthesized from water-glass precursors for CO2 capturing

In this work, porous silica gel-solid beads have been made from economically affordable water-glass precursors via sol-gel nano casting technique. A stable nanometric silica sol was prepared first from water glass and studied for surface potential and sol to gel transition. A free-flow, injectable gel was obtained upon aging the sol which was then assembled into spherical silica beads in a chemical bath. A surface area of 304.7m2g-1 was obtained for water glass derived silica gel beads. These gel beads were impregnated with 3-aminopropyltrimethoxysilane (APTMS) and polyethylenimine (PEI) active functional groups at different percentages for turning the gel beads as sorbents for CO2 gas adsorption. The effect of amine loading on the thermal stability, morphology as well as porosity was studied and was correlated with CO2 adsorption values. Depending upon the amount of amine loaded in the gel support CO2 uptake was found varied. These amine modified silica gel porous adsorbents showed CO2 adsorption capacity at temperatures as low as 100°C; samples modified with 15wt% PEI had CO2 adsorption capacity of 1.16mmolg-1 at 50°C. © 2015 Elsevier B.V

A rare case of pediatric enteroplueural fistula, which presented as lung abscess

We report a case of a 14-year-old male patient referred to us as a case of right-sided lung abscess. The patient was treated for the entericperforation elsewhere, following which he developed productive cough, which progressively worsened. The preoperative diagnosis ofentero-pleural fistula was made with the help of thoraco abdominal computed tomography scan after 4 months of antitubercular andantibiotic treatment. Enteric perforation leading to entero-pleural fistula is very rare. The patient did well after laparotomy and completeexcision of the fistula

Studies on Bracing Member End Connections for Cold Formed Steel Sections

This paper is concentrated mainly on the behaviour of bracing end connections for cold formed steel lipped angle and lipped channel sections. For bracing members, only one flange is possible to connect with tower leg member or supporting member, which causes uneven distribution of stresses in the end section popularly known as shear lag effect. Tension tests have been carried out to simulate the bracing end connections. Special test rig has been assembled and end fittings fabricated such that the load will be applied as concentric load at the pulling end and on the other end load is transferred through the connected flange only. All the specimens have been instrumented with dial gauges, to study the deformations and one specimen is instrumented with strain gauges to study the strain variation. The failure load for tested joints has been calculated by using various International Standards and compared with the test results

Enhanced CO2 absorption kinetics in lithium silicate platelets synthesized by a sol–gel approach

Platelet-shaped lithium orthosilicate particles synthesized by a sol–gel approach employing the precursors lithium nitrate and colloidal silica displayed enhanced absorption kinetics for CO2 compared to the powders prepared by a solid-state reaction process involving Li2CO3 and silica. The sol–gel samples showed a CO2 absorption capacity of 350 mg g-1 at an absorption rate of 22.5 mg g-1 min-1, a value 70% higher than the rate of 13.2 mg g-1 min-1 measured with the solid-state samples under similar conditions. The higher sorption kinetics of CO2 by the sol–gel derived lithium orthosilicate could be attributed to the unique platelet morphology of the particles, which have a very small thickness. A porous carbon mesh coated with the sol–gel based particles exhibited CO2 absorption capacity of 150 mg g-1 at an absorption rate of 37.5 mg g-1 min-1. This supported absorbent also showed stable absorption and desorption performance for the 8 cycles examined in this study. The excellent absorption characteristics of the sol–gel prepared powders, more specifically the coated strips, provide a successful pathway for the commercialisation of these materials

A facile one pot synthetic approach for C3N4-ZnS composite interfaces as heterojunctions for sunlight-induced multifunctional photocatalytic applications

Herein, we report a facile one pot synthetic protocol for the creation of C3N4-ZnS composite interfaces by the co-pyrolysis of a precursor mix containing zinc nitrate, melamine, and thiourea at 550°C in air. The organic-inorganic semiconductor heterojunctions thus formed displayed increased absorbance in the longer wavelength region and facilitated broad absorption of visible light compared to pure ZnS, C3N4 and conventionally synthesized hybrid samples. The decreased emission intensity, increased photocurrent generation and decreased fluorescence lifetime revealed reduced exciton recombinations in the co-pyrolysed sample containing C3N4-ZnS heterostructures. The samples displayed sunlight driven photocatalytic reduction of nitrophenol as well as hydrogen generation (4 mmol g-1 h-1) by water splitting. © The Royal Society of Chemistry 2016

Reactive oxygen species (ROS) mediated enhanced anti-candidal activity of ZnS-ZnO nanocomposites with low inhibitory concentrations

Enhanced antifungal activity against the yeast species Candida albicans, Candida tropicalis and Saccharomyces cerevisiae was displayed by ZnS-ZnO nanocomposites prepared by a simple precipitation technique. The antifungal activity was significantly more in the presence of indoor light than under dark conditions and was a clear confirmation of the inhibitory role of reactive oxygen species (ROS) generated in situ by the photocatalytic nanocomposites. The generation of ROS was further evidenced by flow cytometry results and membrane permeabilisation studies. Time kill assay and growth curve analysis indicated diminished antifungal activity under dark conditions due primarily to Zn2+ efflux in solution. © 2015 The Royal Society of Chemistry

Macrophage Pro-Inflammatory Response to Francisella novicida Infection Is Regulated by SHIP

Francisella tularensis, a Gram-negative facultative intracellular pathogen infecting principally macrophages and monocytes, is the etiological agent of tularemia. Macrophage responses to F. tularensis infection include the production of pro-inflammatory cytokines such as interleukin (IL)-12, which is critical for immunity against infection. Molecular mechanisms regulating production of these inflammatory mediators are poorly understood. Herein we report that the SH2 domain-containing inositol phosphatase (SHIP) is phosphorylated upon infection of primary murine macrophages with the genetically related F. novicida, and negatively regulates F. novicida–induced cytokine production. Analyses of the molecular details revealed that in addition to activating the MAP kinases, F. novicida infection also activated the phosphatidylinositol 3-kinase (PI3K)/Akt pathway in these cells. Interestingly, SHIP-deficient macrophages displayed enhanced Akt activation upon F. novicida infection, suggesting elevated PI3K-dependent activation pathways in absence of SHIP. Inhibition of PI3K/Akt resulted in suppression of F. novicida–induced cytokine production through the inhibition of NFκB. Consistently, macrophages lacking SHIP displayed enhanced NFκB-driven gene transcription, whereas overexpression of SHIP led to decreased NFκB activation. Thus, we propose that SHIP negatively regulates F. novicida–induced inflammatory cytokine response by antagonizing the PI3K/Akt pathway and suppressing NFκB-mediated gene transcription. A detailed analysis of phosphoinositide signaling may provide valuable clues for better understanding the pathogenesis of tularemia

Relationship between cortisol and physical performance in older persons

Objective: Hypercortisolism is associated with muscle weakness. This study examines the relationship between cortisol and physical performance in older persons. Design/patients: The study was conducted within the Longitudinal Aging Study Amsterdam (LASA), an ongoing cohort study in a population-based sample of healthy older persons in the Netherlands. Data from the second (1995/1996) and fourth (2001/2002) cycle were used pertaining to 1172 (65-88 years) and 884 (65-94 years) men and women, respectively. Measurements: Physical performance was measured by adding up scores on the chair stands, tandem stand and walk test (range 0-12). In the second cycle serum total and calculated free cortisol were assessed; in the fourth cycle evening salivary cortisol was assessed. Regression analysis (stratified for sex, adjusted for age, body mass index, alcohol use, physical activity and region) was performed to examine the cross-sectional relationship between cortisol and physical performance. Results: Women with higher calculated free cortisol scored less well on physical performance (b = -0.28 per SD higher cortisol, P = 0.016), which was mainly explained by poorer performance on the tandem stand (OR = 1.32 for a lower score per SD higher cortisol, P = 0.003). Men with higher salivary cortisol scored less well on physical performance (b = -0.90 in the highest vs. the lowest quartile, P = 0.008), which was mainly explained by poorer performance on the chair stands and walk test (OR = 1.88, P = 0.020 and OR = 1.81, P = 0.027, respectively, in the highest vs. the lowest quartile). Conclusion: Physical performance is negatively associated with high cortisol levels in older persons. © 2007 The Authors