Characterization of synthetic hydrocalumite-type [Ca2Al(OH)6]NO3·mH2O: Effect of the calcination temperature

A lamellar hydrocalumite-type [Ca₂Al(OH)₆]NO₃·mH₂O, (HC), was synthesized and characterized by X-ray diffraction analysis (XRD), surface area, pore size measurements, CO₂-Thermal Programmed Desorption, and later tested as catalysts in the double bond isomerization of 1-butene. The layered structure of HC collapses above 523 K yielding an amorphous material at 573 K which upon calcination at 873–973 K transforms into a mixture of CaO and mayenite Ca₁₂Al₁₄O₃₃. The calcination temperature has a marked effect in the formation of basic sites. Thus for example, HC calcined at 1073 K shows 90% of strong basic sites (CO₂ desorption at 1023 K) while they are absent in HC calcined at 573–673 K. HC calcined at 973 K shows high catalytic activity (74% conversion) in the isomerization of 1-butene without any appreciable deactivation after 4 h on stream.     

Plasma levels of parathyroid hormone, vitamin D, calcitonin, and calcium in association with endurance exercise

Nine male marathon runners were investigated during habitual training (week 0), after 3 weeks of training break (week 3), and after 2 weeks (week 5) and 4 weeks (week 7) of retraining. Maximal oxygen uptake, body fat (BF), and plasma levels of 25(OH)D3, 1,25(OH)2D3, parathyroid hormone (PTH), calcitonin (CT), albumin, and albumin-corrected calcium were determined throughout weeks 0-7. The maximal oxygen uptake decreased after training break and increased during retraining (P = 0.002). BF did not change significantly. Plasma 1,25(OH)2D3 was elevated after training break and decreased after 2 and 4 weeks of retraining [week 0: 44.0 +/- 3.7 (SEM) pg x 1(-1); week 3: 52.4 +/- 6.0 pg x 1(-1); week 5: 42.0 +/- 2.8 pg x 1(-1); week 7: 36.9 +/- 2.3 pg x 1(-1); P = 0.03]. Plasma 25(OH)D3 did not change significantly. Plasma PTH increased throughout the training break and retraining (week 0: 1.36 +/- 0.25 pmol x 1(-1); week 3: 2.02 +/- 0.43 pmol x 1(-1); week 5: 2.23 +/- 0.60 pmol x 1(-1); week 7: 2.63 +/- 0.34 pmol x 1(-1); P = 0.03). Albumin-corrected calcium values were transiently decreased during retraining (week 3: 2.77 +/- 0.08 mM; week 5: 2.47 +/- 0.05 mM; week 7: 2.66 +/- 0.07 mM; P = 0.01). Plasma CT did not change during training break, but was transiently decreased during retraining (week 0: 9.97 +/- 0.39 pmol x 1(-1); week 3: 9.91 +/- 0.37 pmol x 1(-1); week 5: 8.19 +/- 0.50 pmol x 1(-1); week 7: 9.02 +/- 0.45 pmol x 1(-1); P = 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

A predictive model to correlate fuel specifications with on-road vehicles emissions in Mexico

Mexico is currently in the process of implementing its third air management program, which includes control measures targeting emissions reductions from mobile, point, and area sources. Achieving the program goals will require changes in the composition and in physical properties of gasoline and implementing an emissions reduction schedule. For that purpose a study was undertaken to support understanding of the effect of gasoline fuel parameters on exhaust emissions. Specifically, the relative impacts of Reid vapor pressure, distillation parameters, oxygen, sulfur, olefins, and aromatic contents on the exhaust emissions of in-use vehicles of the metropolitan area of Mexico City were investigated. The results were used to develop a model to predict CO, nitrogen oxides, total hydrocarbons, and toxic emissions such as benzene, 1,3-butadiene, formaldehyde, and acetaldehyde. Also a statistical model that predicts evaporative emissions was built. Results of the present model are compared with those obtained using the complex model of the United States Environmental Protection Agency.     

Normal brain F-18 FDG-PET and MRI anatomy

Image registration techniques will become increasingly important in correlative multimodality imaging. In the case of PET, a structural imaging study can be invaluable in correlating structure metabolism relationships. A registered brain atlas of PET and MRI has been developed by the authors that allows clinicians, residents, fellows, and others to refer to a structural abnormality on MRI or metabolic abnormality on PET and correlate it neuro-anatomically.     

Oxidative dehydrogenation of 1 -butene to butadiene on α-Fe2O3/ZnAl2O4 and ZnFexAl2-xO4 catalysts

The oxidative dehydrogenation of 1-butene to butadiene was studied over a series of catalysts of iron impregnated on ZnAl₂O₄ used as a support and also Fe coprecipitated with zinc and aluminum in order to obtain ZnFe_xAl_2-xO₄ type catalysts. Results were compared with bulk -Fe₂O₃, ZnAl₂O₄ and ZnFe₂O₄. X-ray diffraction (XRD) and Mössbauer spectroscopy suggest that in the impregnated catalysts, Fe ions are in strong interaction with the support. These samples have higher butadiene selectivity than coprecipitated ZnFe_xAl_2-xO₄ catalysts, in which iron is incorporated into the ZnAl₂O₄ spinel network. Results suggest also that iron content has a greater effect on butadiene selectivity than the zinc aluminate-iron oxide interaction.     

Epithelial p53 gene expression and mutational analysis, combined with growth fraction assessment, in oral lichen planus

A study was undertaken to investigate the relationship between murmur intensity, murmur duration, duration to peak intensity and frequency components with degree of aortic stenosis in boxers. Measurements were made from phonocardiograms obtained from 35 boxers with ejection-type murmurs, and values were compared with those obtained for aortic flow velocity measured by Doppler echocardiography. Murmur intensity graded by auscultation was significantly correlated with aortic flow velocity (P < 0.001), and murmur duration, expressed as a percentage of systole was significantly correlated with aortic flow velocity (P < 0.001), independent of heart rate. Dogs with early systolic murmurs not exceeding 50 per cent of systole had aortic flow velocities of less than 1.5 m/second and no echocardiographic abnormalities, in contrast with dogs with murmurs of longer duration. Dogs with only high frequency components had lower aortic velocities than those that also had components in the medium frequency range (P < 0.01).     

Teachers and game-based learning: Improving understanding of how to increase efficacy of adoption

Interest in game-based learning for K-12 is growing. Thus, helping teachers understand how to use these new pedagogies is important. This paper presents a cross-case study of the development of teacher professional development for the River City project, a games-based multi-user virtual environment science curriculum project for middle school children, over three years of its development. Successful professional development required attention to multiple factors including teacher efficacy in using the software, pedagogical issues and school culture. A theoretical model for successful technological implementations is discussed.     

Remote sensing study of emissions from motor vehicles in the Metropolitan Area of Mexico City

Remote sensing was employed for the first time to measure nitric oxide (NO) levels of on-road light-duty motor vehicles of the Metropolitan Area of Mexico City (MAMC). The sensor placed at 12 different sites also measured the concentration of CO2, CO, and total hydrocarbons (THC) in the exhaust emissions. A database was compiled containing 122 800 readings, of which 84 650 (69%) records were valid emissions measurements. CO, HC, and NO valid readings were 68.9, 63.4, and 62.9%, respectively, of the total attempted measurements. Furthermore, 42 822 vehicles were number-plate-matched to model year with the information provided by the Inspection/Maintenance Program. The mean emissions of total valid readings for CO, HC, and NO were determined to be 1.31 vol %, 440 ppm (propane), and 914 ppm, respectively. In 1991 and 1994, remote sensing measurements of CO and HC tailpipe emissions were performed in the MAMC in five different locations (30 000 valid readings). Large drops in both pollutants were observed for the intervening years, but sufficient vehicle information was not available at that time to fully explain the observed trends. Compared with those reports, our results point out to a steady decrease in CO and HC exhaust emissions with vehicle model year. The fleet emissions measured exhibit a gamma-distribution, with 10% of the most polluting fleet studied being responsible for 45%, 25%, and 29% of the CO, HC, and NO emissions, respectively. NO emissions in taxis are the highest among the vintage of vehicles, a matter of concern since according to the distance traveled per year, they represent 22% of the total activity in the MAMC.     

Mutations in the mineralocorticoid receptor gene cause autosomal dominant pseudohypoaldosteronism type I

We report intractable meningitis and intracranial abscess in a diabetic patient, arising from sphenoid sinusitis and osteomyelitis caused by Candida species. Magnetic resonance images (MRI) revealed the sinusitis and osteomyelitis with direct invasion of the sellar region and clivus, subsequently intracranial abscess.     

On the effects of the sol-gel synthesis parameters on textural and structural characteristics of TiO2

The effects of alcohol/alkoxide, water/alkoxide molar ratios, acid addition, type of solvent, reaction temperature and calcination temperature on textural, structural and morphological characteristics of TiO₂ were studied. The results show that surface area, pore size distribution and crystalline phases were very sensitive to preparation conditions.