Crystallization, microstructure and expansivity of spodumeneorthoclase glasses

The crystallization behaviour was investigated for some glasses, within the system spodumene-orthoclase, during different heat treatments by DTA, XRD and SEM. Kaolin and quartz sand were used as starting materials for the glass preparation and melting. The base glasses were stable through the heat treatments and did not show any crystallization propensity, whereas TiO2 additions catalyze the crystallization tendency in the glasses. The crystallization process involved the formation of β-spodumene and leceite in addition to the metastable high quartz, which disappeared at higher temperatures (>900 °C). Translucent glass-ceramies, containing uniform and nonuniform microstructures, were obtained in the ease of domination of high quartz and β-spodumene, respectively. Little difference in the coefficient of thermal expansion (CTE) was noted in the base glasses (64 to 66 ∙ 10^-7 at 20 to 500 °C) and the TiOs doped glasses (60 to 69 ∙ 10^-7 K^-1 at 20 to 500 °C). Change in CTE in the TiOs doped glass ceramie samples from 37 to 69 ∙ 10^-7 at 20 to 300 °C depends mainly on the content of crystallized β-spodumene in addition to the residual glass. However, an increase in β-spodumene content in the crystallized glass-ceramies lowers the value of CTE and vice versa

Efecto de antioxidantes naturales en la estabilidad de carne de ostra durante su almacenamiento

Meat from the ostrich is becoming increasingly popular throughout the world. The aim of the current study was to evaluate the effects of different antioxidants such as ascorbic acid (AA), α-tocopherol (Toc) and rosemary herb (Ros) on the stability of ostrich meat during storage. The chemical composition of ostrich meat showed low fat content (1.5 %) combined with high protein content (22.4 %). The combination of AA + Ros, Toc + Ros and AA + Toc was more effective in reducing the thiobarbituric acid (TBA) and peroxide values. The antioxidant showed insignificant effects on acidity as oleic acid. The addition of the efficient role of AA, Toc and Ros showed an improvement in the color stability of ostrich steaks and the combined treatment was more effective in color stability. In conclusion, the addition of AA, Toc and Ros had a positive effect on aroma quality, rancidity and discoloration of refrigerated ostrich meat.La carne de ostra es cada vez más popular en todo el mundo. El objetivo de este estudio fue evaluar el efecto de diferentes antioxidantes tales como el ácido ascóbico (AA), el α-tocoferol (Toc) y hierbas de romero (ROS) en la estabilidad de la carne de ostra durante el almacenamiento. La composición química de la carne de ostra mostro un contenido bajo en grasa (1.5%) en combinación con un alto contenido de proteínas (22.4%). Las combinaciones de AA + Ros, Toc + Ros y AA + Toc fueron las más efectiva en la reducción de los valores de ácido tiobarbitúrico (TBA) y de peróxidos. Los antioxidantes muestran un insignificante efecto en la acidez como ácido oleico. La adicción de AA, Toc y Ros mostro una mejora de la estabilidad del color de los filetes de ostra, es más, el tratamiento combinado fue más efectivo en la estabilidad del color. En conclusión, la adicción de AA, Toc y Ros tuvo un efecto positivo en el aroma, rancidez y decoloración de la carne refrigerada de ostra

Comparison between the calculated and measured dose distributions for four beams of 6 MeV linac in a human-equivalent phantom

Radiation dose distributions in various parts of the body are of importance in radiotherapy. Also, the percent depth dose at different body depths is an important parameter in radiation therapy applications. Monte Carlo simulation techniques are the most accurate methods for such purposes. Monte Carlo computer calculations of photon spectra and the dose ratios at surfaces and in some internal organs of a human equivalent phantom were performed. In the present paper, dose distributions in different organs during bladder radiotherapy by 6 MeV X-rays were measured using thermoluminescence dosimetry placed at different points in the human-phantom. The phantom was irradiated in exactly the same manner as in actual bladder radiotherapy. Four treatment fields were considered to maximize the dose at the center of the target and minimize it at non-target healthy organs. All experimental setup information was fed to the MCNP-4b code to calculate dose distributions at selected points inside the proposed phantom. Percent depth dose distribution was performed. Also, the absorbed dose as ratios relative to the original beam in the surrounding organs was calculated by MCNP-4b and measured by thermoluminescence dosimetry. Both measured and calculated data were compared. Results indicate good agreement between calculated and measured data inside the phantom. Comparison between MCNP-4b calculations and measurements of depth dose distribution indicated good agreement between both

Effect of Cr2O3, ZrO2 and LiF on nucleation and crystallization of nepheline syenite-dolomite glass-ceramic compositions

Inexpensive nepheline-pyroxene glass-ceramics of superior mechanical, and thermal properties could be easily prepared from nepheline syenite and dolomite rock mixture by using the conventional glass preparation and heat treatment methods. The parent glass composition, to yield ≈35 % nepheline ss (solid solution) and 65 % diopside ss, was formulated by a modified chemico-mineralogical calculation method after CIPW norm. The effect of the nucleating agents Cr2O3, ZrO2 and LiF on the mechanisms of nucleation and crystallization of these phases were determined by DTA, XRD, as well as optical and electron microscopy. In the absence of these nueleators, crystallization was difficult and semi-crystalline coarse microstructure of diopsidic ss was obtained. LiF showed maximum effect on crystal growth rates, while sufficient nucleation density for glass-ceramic of good quality was achieved by adding Cr2O3 even in the amount as small as 0.5 wt%. Both Cr2O3- and ZrO2-containing samples hindered the crystallization of nepheline but greatly stimulated the epitactic formation of diopside ss of holocrystalline microstructures. LiF-containing samples stimulated the crystallization of the framework silicates, nepheline ss and carnegieite, which progressively increased with the LiF concentration. The thermal expansion coefficient and Vickers hardness of the obtained glass-ceramic reached values of 9.0 × 10^-6 K-1 (20 to 300 °C) and (950 × 10^7 ± 25) N/m2, respectively

The antihyperlipidemic activities of 4(3H) quinazolinone and two halogenated derivatives in rats

In the present study, the effects of subchronic treatments (4 weeks) of hypercholesterolemic (single) and diabetic-hypercholesterolemic (combined) rats with 4 (3H) quinazolinone and 2 halogenated derivatives (6, 8-dibromo-2-methy-4 (3H) quinazolinone and 6-iodo-2-methyl-4(3H) quinazolinone) at a sublethal dose level (2 mg/Kg) on cholesterol metabolism were investigated. Bezafibrate, a hypolipidemic drug was used as a reference compound for data comparison. Treatment of rats with single and combined hypercholesterolemia with quinazolinone compounds gave rise to highly significant reductions in serum total cholesterol and cholesterol ester levels, whereas serum triacylglycerol level was significantly reduced only after treatment with halogen-substituted quinazolinones in single hyper-cholesterolemia, compared to the control group. The effects of different quinazolinones and bezafibrate on reduction of serum LDL-C level were comparable in single hypercholesterolemia but significantly different in combined hypercholesterolemia. Results obtained from this study suggest that the antihyperlipidemic effect of quinazolinone compounds was brought about by inhibition of dietary cholesterol absorption and / or intestinal ACAT activity

Concurrent Acquisition of a Single Nucleotide Polymorphism in Diverse Influenza H5N1 Clade 2.2 Sub-clades

Highly pathogenic Influenza A H5N1 was first identified in Guangdong Province in 1996, followed by human cases in Hong Kong in 1997 1,2. The number of confirmed human cases now exceeds 300 and the associated Case Fatality Rate exceeds 60% 3. The genetic diversity of the serotype continues to increase. Four distinct clades or sub-clades have been linked to human cases 4-7. The gradual genetic changes identified in the sub-clades have been attributed to copy errors by viral encoded polymerases that lack an editing function, thereby resulting in antigenic drift 8. We report here the concurrent acquisition of the same polymorphism by multiple, genetically distinct, clade 2.2 sub-clades in Egypt, Russia, Kuwait, and Ghana. These changes are not easily explained by the current theory of “random mutation” through copy error, and are more easily explained by recombination with a common source. The recombination role is further supported by the high fidelity replication in swine influenza 9 and aggregation of single nucleotide polymorphisms in H5N1 clade 2.2 hemagglutinin 10

Fetal lung volume and pulmonary artery resistance index for prediction of neonatal respiratory distress syndrome

Background: As gestational age grows, the risk of newborn respiratory distress syndrome (RDS) diminishes because the lungs are the last foetal organs to properly mature. While neonatal RDS does not just occur following preterm births, it is often thought of as a disorder of premature babies. This study sought to determine how prenatal lung capacity and foetal Pulmonary artery resistance index (PARI) affected the probability that newborn RDS would occur. Methods: This prospective observational study was carried out on 200 pregnant women aged 20-35 years, with gestational age between 36-40 weeks and singleton pregnancy. According to neonatal outcome the patients were classified into two groups: group A: 26 cases with noenatal RDS and group B: 174 cases without neonatal RDS. All patients were subjected to 2D ultrasonography and 3D ultrasonography. Results: Fetal lung volume (FLV) is a significant predictor of neonatal RDS (AUC: 0.820, p <0.001), at a cut off value of ≤35, with 88.5% sensitivity and 68.4% specificity. PARI is not a significant predictor of neonatal RDS. 1 and 5 min Apgar score were significantly lower in neonates who developed RDS and those who didn’t (p<0.001). Conclusions: 3D FLV and estimated fetal weight measurement using ultrasonography may be a reliable non-invasive indicator of the incidence of newborn RDS in preterm pregnancies when the risk of RDS progression is present. FLV is a significant predictor for neonatal RDS at a cutoff for ≤35 cm3 with sensitivity 88.5% and specificity 68.4%