Thermal-Induced Microstructure Deterioration of Egyptian Granodiorite and Associated Physico-Mechanical Responses.

Mineral transformations often induce microstructural deteriorations during temperature variations. Hence, it is crucial to understand why and how this microstructure weakens due to mineral alteration with temperature and the correlated physical and mechanical responses. Therefore, in this study, physical, chemical, thermal, petrographic, and mechanical analyses were carried out to comprehend better the thermal behaviors of Egyptian granodiorite exposed to temperatures as high as 800 °C. The experimental results indicate that the examined attributes change in three distinct temperature phases. Strength zone (up to 200 °C): During this phase, the temperature only slightly impacts the granodiorite mass loss and porosity, and the P-wave velocity and E slightly decrease. However, the rock structure was densified, which resulted in a minor increase in strength. After that, the transition zone (200-400 °C) was distinguished by the stability of most studied parameters. For instance, mass and porosity did not significantly alter, and the uniaxial compressive strength steadily increased with an axial failure mode. When the temperature rises, transgranular cracks cause the P-wave velocity and elastic modulus to decrease moderately. The decay zone started after 400 °C and continued to 800 °C. This zone is characterized by complicated factors that worsen the granodiorite properties, lead to color shift, and produce a shear failure mode. The properties of granodiorite became worse because of chemical reactions, structural and crystal water evaporation, rising thermal expansion coefficient variation, and quartz inversion at 575 °C (α to ß, according to the differential thermal analysis). Thermal damage greatly affected granodiorite's physical and mechanical properties and microstructure at 800 °C. As a result, UCS measurements were extremely small with a complex failure pattern, making Vp and E unattainable.

Body mass index in Saudi Arabian children and adolescents: a national reference and comparison with international standards.

BACKGROUND AND OBJECTIVES: Because there are no reference standards for body mass index (BMI) in Saudi children, we established BMI reference percentiles for normal Saudi Arabian children and adolescents and compared them with international standards. SUBJECTS AND METHODS: Data from a stratified multistage probability sample were collected from the 13 health regions in Saudi Arabia, as part of a nationwide health profile survey of Saudi Arabian children and adolescents conducted to establish normal physical growth references. Selected households were visited by a trained team. Weight and length/height were measured and recorded following the WHO recommended procedures using the same equipment, which were subjected to both calibration and intra/interobserver variations. RESULTS: Survey of 11 874 eligible households yielded 35 275 full-term and healthy children and adolescents who were subjected to anthropometric measurements. Four BMI curves were produced, from birth to 36 months and 2 to 19 years for girls and boys. The 3rd , 5 th , 10th , 25th , 50th , 75th , 85th , 90th , 95th , and 97th percentiles were produced and compared with the WHO and CDC BMI charts. In the higher percentiles, the Saudi children differed from Western counterparts, indicating that Saudi children have equal or higher BMIs. CONCLUSION: The BMI curves reflect statistically representative BMI values for Saudi Arabian children and adolescents.

Prevalence of type 1 diabetes mellitus in Saudi Arabian children and adolescents.

OBJECTIVE: To determine the prevalence of type 1 diabetes mellitus among 0-19 years old Saudi children and adolescents. METHODS: A nationwide Saudi Arabian project was conducted in the years 2001-2007 with the objective of establishing national growth charts, and defining the prevalence of some chronic childhood diseases such as diabetes mellitus. The 14,000 households were randomly selected based on a recent population statistic. The questionnaire used included demographic data and evidence of diabetes mellitus. The prevalence was estimated and expressed per 100,000. Breakdown of this figure per age and region was carried out. RESULTS: In the 11,874 out of the 14,000 84.9% selected households, 45,682 children and adolescents were surveyed. Fifty children and adolescents were identified to have type 1 diabetes mellitus with a prevalence rate of 109.5 per 100,000. The male to female ratio was almost equal (26 males and 24 females). The distribution of prevalence of type 1 diabetes mellitus by region shows that the highest was 162 in the central region, and the lowest was 48 in the eastern region. Children and adolescents were also grouped by age into 5-6 (prevalence 100), 7-12 (prevalence 109), 13-16 (prevalence 243), and 17-18 (prevalence 150). CONCLUSION: We conclude that the prevalence of type 1 diabetes mellitus in Saudi Arabian children and adolescents is 109.5 per 100,000.