Improved Refractory Aluminosilicate Bricks Through Nano Zirconia Additions

The physico-mechanical and refractory properties of refractory bricks, prepared from 50 wt.% kaolin and 50 wt.% alumina, were improved through the addition of different contents (2, 4, 6, 8 and 10 wt. %) of nano zirconia powder. The densification parameters (bulk density and apparent porosity), mechanical properties (cold crushing strength) and refractory properties (thermal shock resistance) were tested for the prepared refractory bricks fired at 1500 oC. The mineralogical composition of the prepared zirconia and the refractory bricks were followed by X-ray diffraction analysis (XRD) whereas while their microstructure and chemical constituents were depicted using scanning electron microscope attached with energy dispersive x-ray unit (SEM + EDAX). The refractory brick samples containing 8 wt. % of nano zirconia was considered as the optimum among the investigated samples as it shows the best sintering, mechanical and refractory properties, these were correlated with their recognized assemblage of minerals; mullite-cristobalite-zirconia

Grey and white matter correlates of recent and remote autobiographical memory retrieval:Insights from the dementias

The capacity to remember self-referential past events relies on the integrity of a distributed neural network. Controversy exists, however, regarding the involvement of specific brain structures for the retrieval of recently experienced versus more distant events. Here, we explored how characteristic patterns of atrophy in neurodegenerative disorders differentially disrupt remote versus recent autobiographical memory. Eleven behavioural-variant frontotemporal dementia, 10 semantic dementia, 15 Alzheimer's disease patients and 14 healthy older Controls completed the Autobiographical Interview. All patient groups displayed significant remote memory impairments relative to Controls. Similarly, recent period retrieval was significantly compromised in behavioural-variant frontotemporal dementia and Alzheimer's disease, yet semantic dementia patients scored in line with Controls. Voxel-based morphometry and diffusion tensor imaging analyses, for all participants combined, were conducted to investigate grey and white matter correlates of remote and recent autobiographical memory retrieval. Neural correlates common to both recent and remote time periods were identified, including the hippocampus, medial prefrontal, and frontopolar cortices, and the forceps minor and left hippocampal portion of the cingulum bundle. Regions exclusively implicated in each time period were also identified. The integrity of the anterior temporal cortices was related to the retrieval of remote memories, whereas the posterior cingulate cortex emerged as a structure significantly associated with recent autobiographical memory retrieval. This study represents the first investigation of the grey and white matter correlates of remote and recent autobiographical memory retrieval in neurodegenerative disorders. Our findings demonstrate the importance of core brain structures, including the medial prefrontal cortex and hippocampus, irrespective of time period, and point towards the contribution of discrete regions in mediating successful retrieval of distant versus recently experienced events

Synthesis, magnetic and optical properties of core/shell Co1-xZnxFe2O4/SiO2 nanoparticles

The optical properties of multi-functionalized cobalt ferrite (CoFe2O4), cobalt zinc ferrite (Co0.5Zn0.5Fe2O4), and zinc ferrite (ZnFe2O4) nanoparticles have been enhanced by coating them with silica shell using a modified Stöber method. The ferrites nanoparticles were prepared by a modified citrate gel technique. These core/shell ferrites nanoparticles have been fired at temperatures: 400°C, 600°C and 800°C, respectively, for 2 h. The composition, phase, and morphology of the prepared core/shell ferrites nanoparticles were determined by X-ray diffraction and transmission electron microscopy, respectively. The diffuse reflectance and magnetic properties of the core/shell ferrites nanoparticles at room temperature were investigated using UV/VIS double-beam spectrophotometer and vibrating sample magnetometer, respectively. It was found that, by increasing the firing temperature from 400°C to 800°C, the average crystallite size of the core/shell ferrites nanoparticles increases. The cobalt ferrite nanoparticles fired at temperature 800°C; show the highest saturation magnetization while the zinc ferrite nanoparticles coated with silica shell shows the highest diffuse reflectance. On the other hand, core/shell zinc ferrite/silica nanoparticles fired at 400°C show a ferromagnetic behavior and high diffuse reflectance when compared with all the uncoated or coated ferrites nanoparticles. These characteristics of core/shell zinc ferrite/silica nanostructures make them promising candidates for magneto-optical nanodevice applications

Utilization of granodiorite in the production of porcelainstoneware tiles

In the present study, the use of granodiorite, as fluxing agent in a body mix for stoneware ceramic tiles production, was assessed. Fourbatches were formulated using clay from Khaboba, and natural granodiorite from Saint Katherine, Sinai, Egypt. The batches weretailored to completely replace both feldspatic and inert components of stoneware ceramic tiles. Densification was studied according toISO rules, while sinterability was estimated by optical dilatometry. The dependence of microstructure and mechanical properties ofstoneware ceramic tiles on granodiorite content was discussed. Strength measurements showed that increasing granodiorite content thebending strength of the bodies increased. In particular the studied batches can be used for the production of industrial fast firing tiles.The obtained ceramic tiles possess properties similar to commercial ceramic floor and/or wall tiles

Propulsion System Issues in Hybrid Electric Vehicle

Hybrid Electric Vehicle (HEV) are the most promising alternatives to conventional Internal Combustion Engine Vehicle (ICEV) which satisfy increasing customer requirements such as fuel economy, ordinary road performance and drive-ability at minimum cost. This paper focusing on HEV performance of electrical system such as battery and electric motor drives. Mathematical models and simulation using MATLAB/SIMULINK is presented and implemented in a complete series–parallel HEV model from MATLAB/SIMULINK. Finally, simulation results are presented to demonstrate the effectiveness and applicability of the proposed system in the real-time implementation. Keywords: Hybrid Electric Vehicle (HEV), Permanent Magent Synchronous Motor (PMSM), Simulation of HEV

Utilization of granodiorite in the production of porcelain stoneware tiles

In the present study, the use of granodiorite, as fluxing agent in a body mix for stoneware ceramic tiles production, was assessed. Fourbatches were formulated using clay from Khaboba, and natural granodiorite from Saint Katherine, Sinai, Egypt. The batches weretailored to completely replace both feldspatic and inert components of stoneware ceramic tiles. Densification was studied according toISO rules, while sinterability was estimated by optical dilatometry. The dependence of microstructure and mechanical properties ofstoneware ceramic tiles on granodiorite content was discussed. Strength measurements showed that increasing granodiorite content thebending strength of the bodies increased. In particular the studied batches can be used for the production of industrial fast firing tiles.The obtained ceramic tiles possess properties similar to commercial ceramic floor and/or wall tiles

Utilization of granodiorite in the production of porcelain stoneware tiles

In the present study, the use of granodiorite, as fluxing agent in a body mix for stoneware ceramic tiles production, was assessed. Fourbatches were formulated using clay from Khaboba, and natural granodiorite from Saint Katherine, Sinai, Egypt. The batches weretailored to completely replace both feldspatic and inert components of stoneware ceramic tiles. Densification was studied according toISO rules, while sinterability was estimated by optical dilatometry. The dependence of microstructure and mechanical properties ofstoneware ceramic tiles on granodiorite content was discussed. Strength measurements showed that increasing granodiorite content thebending strength of the bodies increased. In particular the studied batches can be used for the production of industrial fast firing tiles.The obtained ceramic tiles possess properties similar to commercial ceramic floor and/or wall tiles

Effect of Nanospinel Additions on the Sintering of Magnesia–Zirconia Ceramic Composites

International audienceNanocrystalline magnesium aluminate (MA) spinel powder produced through a coprecipitation method and calcined at 900 C for 1 h was added to magnesia-zirconia composite in the range of 0-25 mass % and sintered at 1600 C for 2 h. Scanning electron microscope (SEM) and X-ray diffraction (XRD) techniques were used for studying the microstructure and the phase composition of the sintered composites. Bulk density, apparent porosity, volume shrinkage, and Young's modulus of the sintered composites were also investigated. The results revealed that the nanospinel addition up to 20 mass % increases the sintering ability and Young's modulus of the composite bodies. Microstructure showed that the presence of nanospinel and zirconia in the triple point between magnesia grains closed the gaps in the ceramic matrix and enhanced the compactness of the composites

GSTM1, GSTT1 and EPHX1 gene polymorphisms and susceptibility to COPD in a sample of Egyptian population

Background: Gene polymorphisms and COPD susceptibility have been paid special attention and were explored in a large number of studies. The results varied between studies and populations. We aimed to analyze the relation between susceptibility to COPD and polymorphisms of Glutathione S-transferases (GST); GSTM1, GSTT1 and Microsomal epoxide hydrolase-1 (EPHX1) genes in a sample of Egyptian population. Methods: Genetic polymorphisms of GSTM1, GSTT1 and EPHX1 genes in 146 COPD patients and 130 controls were investigated using multiplex PCR for GSTM1 and GSTT1 genes and PCR-RFLP for EPHX1 genes. Results: The frequency of GSTM1-null genotype was higher in patients than in controls (72.6% versus 43.8%, P < 0.001). Carriers with both null GSTT1 and GSTM1 genes were at a higher risk of COPD (OR 3.45, 95% CI = 1.07–11.14). The frequency of EPHX1 exon 3 His allele was higher in patients than controls (19.2% versus 12.7%, P = 0.04). Carriers with exon 3 His allele were at a higher risk of COPD (OR 1.63, 95% CI = 1.02–2.6, P = 0.04). Carriers with both GSTM1-null and EPHX1 113Tyr/Tyr or EPHX1 113Tyr/His genotypes were at a higher risk of COPD (OR 3.33, 95% CI = 1.32–8.35 and OR 14.24, 95% CI = 3.02–67.17 respectively). Carriers with both GSTM1-null and EPHX1 139His/His genotypes were at a higher risk of COPD (OR 5.58, 95% CI = 2.14–14.52). Conclusions: EPHX1 exon 3 His allele in addition to the coexistence of other genetic variants, were significant risk factors in susceptibility to COPD in the Egyptian population