Tea and coffee consumption in relation to vitamin D and calcium levels in Saudi adolescents

ABSTRACT: BACKGROUND: Coffee and tea consumption was hypothesized to interact with variants of vitamin D-receptor polymorphisms, but limited evidence exists. Here we determine for the first time whether increased coffee and tea consumption affects circulating levels of 25-hydroxyvitamin D in a cohort of Saudi adolescents. METHODS: A total of 330 randomly selected Saudi adolescents were included. Anthropometrics were recorded and fasting blood samples were analyzed for routine analysis of fasting glucose, lipid levels, calcium, albumin and phosphorous. Frequency of coffee and tea intake was noted. 25-hydroxyvitamin D levels were measured using enzyme-linked immunosorbent assays. RESULTS: Improved lipid profiles were observed in both boys and girls, as demonstrated by increased levels of HDL-cholesterol, even after controlling for age and BMI, among those consuming 9--12 cups of coffee/week. Vitamin D levels were significantly highest among those consuming 9--12 cups of tea/week in all subjects (p-value 0.009) independent of age, gender, BMI, physical activity and sun exposure. CONCLUSION: This study suggests a link between tea consumption and vitamin D levels in a cohort of Saudi adolescents, independent of age, BMI, gender, physical activity and sun exposure. These findings should be confirmed prospectively.     

A model for measuring e-learning systems success in universities

In the era of internet, universities and higher education institutions are increasingly tend to provide e-learning. For suitable planning and more enjoying the benefits of this educational approach, a model for measuring success of e-learning systems is essential. So in this paper, we try to survey and present a model for measuring success of e-learning systems in universities. For this purpose, at first, according to literature review, a conceptual model was designed. Then, based on opinions of 33 experts, and assessing their suggestions, research indicators were finalized. After that, to examine the relationships between components and finalize the proposed model, a case study was done in 5 universities: Amir Kabir University, Tehran University, Shahid Beheshti University, Iran University of Science & Technology and Khaje Nasir Toosi University of Technology. Finally, by analyzing questionnaires completed by 369 instructors, students and alumni, which were e-learning systems user, the final model (MELSS Model¹).     

The impact of website content dimension and e-trust on e-marketing effectiveness: The case of Iranian commercial saffron corporations

By considering the problems that commercial saffron companies have faced in international markets, the aim of this study is to investigate the impact of website content, including informational and design dimensions, on the effectiveness of e-marketing and e-trust as mediator variables. These aspects are examined with reference to sales and marketing division managers in a sample of 100 commercial saffron corporations in the Khorasan province. The findings support the ideas that website content has an effect on e-marketing and e-trust and that e-trust plays a mediating role in the relationship between e-trust and e-marketing effectiveness.     

Preparation, characterization and application of advanced isoconversional kinetics to epoxy/1,4-Bis(3-aminopropoxy) butane/MWCNT nanocomposite

A novel nanocomposite consisting bisphenol A diglycidyl ether/1,4-Bis(3-aminopropoxy) butane (1,4-APB)/multiwall carbon nanotube (MWCNT) was synthesized and characterized. Kinetics of the reaction was described by applying differential scanning calorimetry (DSC) data to isoconversional methods of Flynn-Wall-Ozawa (FWO), advanced isoconversional method of Vyazovkin, and non-linear integral isoconversional algorithm (NLN). It was found that at the presence of MWCNT the thermal decomposition temperature increased by rising the curing temperature and time. Data from dynamic mechanical thermal analysis (DMTA) showed that the glass transition temperature of the cured nanocomposite is 7 °C higher than that value found for the system without carbon nanotube. Scanning electron microscopy (SEM) was used to observe the fracture surface morphology and results indicated evidence of the interfacial interaction improvement and adhesion strength due to good dispersion of MWCNT.     

Resistance of exterior three-dimensional walls to high velocity projectiles

There have been a number of recent civilian deaths due to ammunition from commonly used firearms penetrating exterior walls of residential, public, and commercial buildings. Experimental research was conducted to study the behavior of three-dimensional (3D) exterior walls when subjected to high velocity projectiles or bullets fired from a variety of firearms of different calibers. Four types of firearms were used, namely, a 9 mm gun, a 0.357 Magnum gun, an M16 machine gun, and a 7.62 Clashin Koff machine gun. The size of chips and the depth of penetrations produced by the fired bullets are documented and discussed. It was found that none of the fired bullets penetrated the two reinforced concrete layers of the exterior wall. In conclusion, 3D exterior walls provide an acceptable level of protection from ammunition fired from commonly used firearms.     

Engineering prediction of soot concentration in the primary zone of the gas turbine combustor

The trends towards using heavier fuel oil in the gas turbine engine will increase the soot formation rate in the primary zone, which increases flame radiation and impairs flame tube durability. Therefore, devising a method to determine quantitiatively the soot concentration is of paramount importance, as it helps in combustor design and pollution control. The method proposed adopts the Schmidt technique for radiation measurements together with soot formation and oxidation models. The soot concentration predictions from this method have been compared with those calculated from measurements of radiation in the primary zone and exhaust smoke at the combustor exit. Favourable comparison was achieved, especially under full load conditions.     

Chemopreventive Potential of Flavonoid Extracts from Plantation-Bred and Wild Aronia melanocarpa (Black Chokeberry) Fruits

ABSTRACT:  European plantation-bred (cultivated) and local Illinois (wild) Aronia melanocarpa (chokeberry) fruits were extracted with 70% aqueous acetone and separated into 6 fractions using vacuum liquid chromatography (VLC) over a Toyopearl (TP) polymer column. TP fractions 2 through 6 were recombined and further subfractionated using silica gel (SG) into 22 subfractions. Crude extract, TP fractions, and SG subfractions were screened in a L1210 murine leukemia cell assay and a human DNA catalytic topoisomerase II assay in order to gauge the cancer chemopreventive potential of each genotype. SG subfraction 6 from the cultivated genotype showed >90% inhibitory activity at 25 μg/mL, and a similar fraction from the wild genotype showed >95% inhibitory activity to L1210 leukemia cells at a concentration of 50 μg/mL. On the basis of topoisomerase inhibition, it can be concluded that all TP fractions of the wild genotype act as catalytic inhibitors. Similar anthocyanins and oligomeric proanthocyanidins were identified from both Aronia genotypes; however, HPLC-ESI-MS spectra indicated higher flavonoid concentration in the wild Aronia and a predominance (up to 67%) of nonphenolic compounds in the berries from the cultivated genotype. Both cultivated and wild genotypes exhibited promise toward chemoprevention, but differed in levels of activity in the assays used to determine chemoprotective potential.     

Preparation and evaluation of functionalized goethite nanorods coated by molecularly imprinted polymer for selective extraction of bisphenol A in aqueous medium

Molecular imprinting method is widely used to recognize various templates. Recognition of bisphenol A (BPA) as a harmful template is important. Herein a novel BPA molecular imprinted polymer nanoparticles (BMIPN) is reported by core-shell surface molecular imprinting technology. In this process, BPA was imprinted by polymerizing methacrylic acid (MAA) as functional monomer, in presence of ethylene glycol dimethacrylate (EGDMA) as a cross-linker and goethite nanorods (GNR) functionalized with fumaric acid. The formation of different materials in different steps was confirmed by Fourier transform infrared spectroscopy (FT-IR), the size and surface morphological of material was observed by field emission scanning electron microscopy (FESEM) and Transmission electron microscopy (TEM). The BMIPN structure was characterized by X-ray diffraction (XRD) and thermal gravimetric analysis (TGA). The important effective factors on adsorption process such as pH, contact time, amount of GNR, initial concentration of BPA, release and reusability and selectivity of BMIPN were studied. The excellent selectivity behavior of BMIPN was evaluated in the presence of phenol (Ph), 4, 4′-biphenol (BPh), hydroquinone (HQ) and 2, 2′-Bis(4-hydroxyphenyl)butane (BPB), as interferences. Based on the isotherm and kinetic studies, the experimental data obey Langmuir isotherm and the pseudo-second-order kinetic models. The results showed that BMIPN had excellent properties for adsorbing BPA in a short time even in the presence of analogous.