Search Results (5)

Surface-enhanced Raman scattering (SERS) for semiconductor nanomaterial systems is limited due to weak Raman signal intensity and unclear charge-transfer (CT) processes for chemical enhancement. Here, rare-earth element neodymium-doped titanium dioxide (Nd-TiO₂) nanoparticles (NPs) were synthesized by the sol–gel method. The characterizations show that the doping of Nd ions causes TiO₂ NPs to show an increase in the concentration of defects and change in the energy level structure. The CT process between Nd-TiO₂ NPs substrate and probe molecule 4-Mercaptopyridine (4-Mpy) was innovatively analyzed using the relative energy level location relationship of the Dorenbos model. The SERS signal intensity exhibits an exponential enhancement with increasing Nd doping concentration and reaches its optimum at 2%, which is attributed to two factors: (1) The increase in the defect concentration is beneficial to the CT process between the TiO₂ and the probe molecule; (2) the introduction of 4f electron orbital energy levels of rare-earth ions created unique CT process between Nd³⁺ and 4-Mpy. Moreover, the Nd-TiO₂ NPs substrate shows excellent SERS performance in Raman signal reproducibility (RSD = 5.31%), the limit of detection (LOD = 10⁻⁶ M), and enhancement factor (EF = 3.79 × 10⁴). Our work not only improves the SERS performance of semiconductor substrates but also provides a novel approach to the development of selective detection of probe molecules. Full article

Previous studies demonstrated that hyperglycemic glucose concentrations are observed in children that are overweight or have obesity. The aim of this study was to evaluate the effect of a 12 month lifestyle intervention on free-living glycemic profiles in children that were overweight or had obesity, and the association of the alterations with changes in cardiovascular risk parameters. BMI z-score, free-living glycemic profiles, continuous overlapping net glycemic action (CONGA), and cardiovascular parameters were evaluated before and after a multidisciplinary lifestyle intervention, in 33 non-diabetic children that were overweight or had obesity. In children with a decrease in BMI z-score, the duration which glucose concentrations were above the high-normal threshold (6.7 mmol/L) and the glycemic variability decreased significantly. In these children, a decrease in median sensor glucose was associated with decreases in LDL-cholesterol, and systolic and diastolic blood pressure z-score. A decrease in BMI z-score was associated with a decrease in CONGA1, 2, and 4. In conclusion, the glycemic profiles in free-living conditions in children that were overweight improved in children with a decrease in BMI z-score after lifestyle intervention. In those children, changes in median sensor glucose concentrations were associated with changes in LDL-cholesterol and blood pressure z-scores. These results suggest that glucose homeostasis can improve after one year of lifestyle intervention and that these improvements are associated with improvements in cardiovascular health parameters. Full article

The objective was to assess the effects of a weight loss and subsequent weight maintenance period comprising two diets differing in protein intake, on brain reward reactivity to visual food cues. Brain reward reactivity was assessed with functional magnetic resonance imaging in 27 overweight/obese individuals with impaired fasting glucose and/or impaired glucose tolerance (HOMA-IR: 3.7 ± 1.7; BMI: 31.8 ± 3.2 kg/m²; fasting glucose: 6.4 ± 0.6 mmol/L) before and after an 8-week low energy diet followed by a 2-year weight maintenance period, with either high protein (HP) or medium protein (MP) dietary guidelines. Brain reactivity and possible relationships with protein intake, anthropometrics, insulin resistance and eating behaviour were assessed. Brain reactivity, BMI, HOMA-IR and protein intake did not change differently between the groups during the intervention. In the whole group, protein intake during weight maintenance was negatively related to changes in high calorie images>low calorie images (H > L) brain activation in the superior/middle frontal gyrus and the inferior temporal gyrus (p < 0.005, corrected for multiple comparisons). H > L brain activation was positively associated with changes in body weight and body-fat percentage and inversely associated with changes in dietary restraint in multiple reward, gustatory and processing regions (p < 0.005, corrected for multiple comparisons). In conclusion, changes in food reward-related brain activation were inversely associated with protein intake and dietary restraint during weight maintenance after weight loss and positively associated with changes in body weight and body-fat percentage. Full article

Sr2SiS4:Ce3+ is an efficient blue-emitting (460 nm) phosphor, excitable with light of wavelengths up to 420 nm. From the excitation spectrum, we construct the energy level scheme and use it to check the predictive power of the Dorenbos model, relating the positions of the Ce3+ energy levels with those of Eu2+ in the same host. For strontium thiosilicate, this method gives excellent results and allows us to determine which of two available crystallographic sites is occupied by cerium. We use the Dorenbos method for extracting information on the coordination of Ce3+ from the observed crystal field splitting. Full article