Thermoelectric Properties of Oxide Semiconductors

In this chapter, we have explored the potential of oxide semiconductors for thermoelectric power generation. Various oxides (Cu2InO4, CuAlO2, and Zn2GeO4) were grown on Si substrate by thermal evaporation method using tube furnace. After the growth, a representative sample of each oxide was cut into pieces and was annealed at various temperatures from 600 to 800°C in oxygen environment for 1 h using a programmable furnace. The structure of all annealed sample was verified by performing X-ray powder diffraction (XRD) measurements. XRD data suggested that all oxide materials show crystalline behavior at annealing temperature 800°C. XRD results further confirmed that crystal structure of investigated samples improved significantly with annealing because the intensity of oxygen-sensitive (0 0 6) plane was found to be increased with annealing temperature. To investigate the thermoelectric properties of annealed samples, Seebeck effect and Hall effect measurements were performed in the temperature range 25–100°C. It was found that the value of Seebeck coefficient and power factor increased as the annealing temperature increases. Zn2GeO4 was found to be a potential thermoelectric material because it has the highest value of Seebeck coefficient and power factor. This highest value is related to the presence of secondary phases in this oxide

Evaluation of antioxidant activity of steviol glucoside commercial powder in neutral and acidic pH

Introduction. Current trends on new food products aim to incorporate biopolymers to improve their physicochemical stability, such as Stevia rebaudiana. Furthermore, due to its high sweetening potential, commercial steviol glucoside (CSP) powder has been recently incorporated into food formulation for its antioxidant capacity. Objective. This study focused on the evaluation of antioxidant capacity of commercial steviol glucoside powder, under both neutral and acidic pH conditions (3.5-7) at concentrations ranging from 100-500 µg/mL. Material and Methods. Tests were assessed in triplicate for a sample of CSP, available in Algeria, by using 2, 2-diphenyl-1-picrylhydrazyl free radical scavenging method (DPPH). Total phenolic compounds were measured in 100µg with Folin-Ciocalteu. Results. Commercial powder of steviol glucoside presented a total polyphenols content of 2.500±0.0150 mg/g of CSP dry weight, and exhibited a significant inhibitory percentage of DPPH. Values were ranged of 35.89±0.16% to 62.32±0.45% in neutral pH, and were between 40.21±0.04% to 65.00±0.26% in acidic pH. Data showed that inhibitory concentration IC50 against DPPH was ranged of 208.204 µg/mL in neutral pH, and 269.547 µg/mL in acidic pH. Conclusion. Commercial stevioside powder can be used not only as sweetener, but also as poly-phenols source with antioxidant activity in the preparation of neutral and acidic low calorie functional foods

In vivo antidiabetic effect and antioxidant potential of Stevia Rebaudiana mixed with Tragacanth gum in orange nectar

The objective of this research was to develop a novel low-sugar orange nectar using Stevia Rebaudiana and tragacanth gum, aiming to enhance the anti-hyperglycemic effect and antioxidant stability. The experimental design involved varying two levels of Stevia and tragacanth gum, including central points. The oxidative stability and organoleptic test were required for the selection. The impact of daily consumption of the optimal nectar on postprandial glycemia was assessed in diabetic Wistar rats.The results demonstrated that formulation F1, containing 0.5% tragacanth and 0.03% Stevia, achieved the highest organoleptic score (9.55) and exhibited the greatest stability, with half-life times of 83.87 days at 4 °C and 76.26 days at 25 °C. The in-vivo antidiabetic study revealed a positive effect of this formulation in preventing postprandial hyperglycemia and weight gain. This research clearly highlights the importance of incorporating 0.03% Stevia and 0.5% tragacanth in the formulation of low-sugar orange nectar to ensure functional efficacy and technological stability

Nanocurcumin-Based Sugar-Free Formulation: Development and Impact on Diabetes and Oxidative Stress Reduction

International audienceThe objective of this study is the development of innovative nanocurcumin-based formulations designed for the treatment and prevention of oxidative stress and diabetes. Nanocurcumin was obtained through a micronization process and subsequently encapsulated within biopolymers derived from corn starch and fenugreek mucilage, achieving encapsulation rates of 75% and 85%, respectively. Subsequently, the encapsulated nanocurcumin was utilized in the formulation of sugar-free syrups based on Stevia rebaudiana Bertoni. The stability of the resulting formulations was assessed by monitoring particle size distribution and zeta potential over a 25-day period. Dynamic light scattering (DLS) revealed a particle size of 119.9 nm for the fenugreek mucilage-based syrup (CURF) and 117 nm for the corn starch-based syrup (CURA), with polydispersity indices PDIs of 0.509 and 0.495, respectively. The dissolution rates of the encapsulated nanocurcumin were significantly enhanced, showing a 67% improvement in CURA and a 70% enhancement in CURF compared with crude curcumin (12.82%). Both formulations demonstrated excellent antioxidant activity, as evidenced by polyphenol quantification using the 2.2-diphenyl 1-pycrilhydrazyl (DPPH) assay. In the evaluation of antidiabetic activity conducted on Wistar rats, a substantial reduction in fasting blood sugar levels from 392 to 187 mg/mL was observed. The antioxidant properties of CURF in reducing oxidative stress were clearly demonstrated by a macroscopic observation of the rats’ livers, including their color and appearance

Genetic Risk Score for Intracranial Aneurysms: Prediction of Subarachnoid Hemorrhage and Role in Clinical Heterogeneity

Background:Recently, common genetic risk factors for intracranial aneurysm (IA) and aneurysmal subarachnoid hemorrhage (ASAH) were found to explain a large amount of disease heritability and therefore have potential to be used for genetic risk prediction. We constructed a genetic risk score to (1) predict ASAH incidence and IA presence (combined set of unruptured IA and ASAH) and (2) assess its association with patient characteristics. Methods:A genetic risk score incorporating genetic association data for IA and 17 traits related to IA (so-called metaGRS) was created using 1161 IA cases and 407 392 controls from the UK Biobank population study. The metaGRS was validated in combination with risk factors blood pressure, sex, and smoking in 828 IA cases and 68 568 controls from the Nordic HUNT population study. Furthermore, we assessed association between the metaGRS and patient characteristics in a cohort of 5560 IA patients. Results:Per SD increase of metaGRS, the hazard ratio for ASAH incidence was 1.34 (95% CI, 1.20-1.51) and the odds ratio for IA presence 1.09 (95% CI, 1.01-1.18). Upon including the metaGRS on top of clinical risk factors, the concordance index to predict ASAH hazard increased from 0.63 (95% CI, 0.59-0.67) to 0.65 (95% CI, 0.62-0.69), while prediction of IA presence did not improve. The metaGRS was statistically significantly associated with age at ASAH (beta=-4.82x10(-3) per year [95% CI, -6.49x10(-3) to -3.14x10(-3)]; P=1.82x10(-8)), and location of IA at the internal carotid artery (odds ratio=0.92 [95% CI, 0.86-0.98]; P=0.0041). Conclusions:The metaGRS was predictive of ASAH incidence, although with limited added value over clinical risk factors. The metaGRS was not predictive of IA presence. Therefore, we do not recommend using this metaGRS in daily clinical care. Genetic risk does partly explain the clinical heterogeneity of IA warranting prioritization of clinical heterogeneity in future genetic prediction studies of IA and ASAH