Solution‐Processed GaSe Nanoflake‐Based Films for Photoelectrochemical Water Splitting and Photoelectrochemical‐Type Photodetectors

Gallium selenide (GaSe) is a layered compound, which has been exploited in nonlinear optical applications and photodetectors due to its anisotropic structure and pseudodirect optical gap. Theoretical studies predict that its 2D form is a potential photocatalyst for water splitting reactions. Herein, the photoelectrochemical (PEC) characterization of GaSe nanoflakes (single‐/few‐layer flakes), produced via liquid phase exfoliation, for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in both acidic and alkaline media is reported. In 0.5 m H₂SO₄, the GaSe photoelectrodes display the best PEC performance, corresponding to a ratiometric power‐saved metric for HER (Φ_saved,HER) of 0.09% and a ratiometric power‐saved metric for OER (Φ_saved,OER) of 0.25%. When used as PEC‐type photodetectors, GaSe photoelectrodes show a responsivity of ≈0.16 A W^?1 upon 455 nm illumination at a light intensity of 63.5 µW cm^?2 and applied potential of ?0.3 V versus reversible hydrogen electrode (RHE). Stability tests of GaSe photodetectors demonstrated a durable operation over tens of cathodic linear sweep voltammetry scans in 0.5 m H₂SO₄ for HER. In contrast, degradation of photoelectrodes occurred in both alkaline and anodic operation due to the highly oxidizing environment and O₂‐induced (photo)oxidation effects. The results provide new insight into the PEC properties of GaSe nanoflakes for their exploitation in photoelectrocatalysis, PEC‐type photodetectors, and (bio)sensors.     

A reexamination of the relation between halo error and accuracy.

The traditional assumption has been that halo error is negatively related to accuracy of ratings. W. H. Cooper (1981) evaluated this assumption by examining correlation coefficients between measures of accuracy and halo error from five earlier studies of performance and trait ratings. Because the correlation coefficients were typically positive, Cooper concluded that a "paradoxical" positive relation exists between halo error and accuracy. However, there is no paradox; some of these positive correlation coefficients were between halo error and inaccuracy, whereas others were based on analyses that did not take into consideration negative halo errors. When analyses that correct these problems were performed on two sets of data (R. Tallarigo, 1986, n?=?107; R. J. Vance, K. W. Kuhnert, & J. L. Farr, 1978, n?=?112), all significant (p?negative. The use of halo error measures, the possibility of negative halo errors, and implications of the results for rater training are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An ASM-based characterisation of starvation-free systems

Abstract State Machines (ASMs) have been successfully applied for modeling critical and complex systems in a wide range of application domains. However, unlike other well-known formalisms, e.g. Petri nets, ASMs lack inherent, domain-independent characterisations of computationally important properties. Here, we provide an ASM-based characterisation of the starvation-free property. The classic, informal notion of starvation, usually provided in literature, is analysed and expressed as a necessary condition in terms of ASMs. Thus, we enrich the ASM framework with the notion of vulnerable rule as a practical tool for analysing starvation issues in an operational fashion.     

Vitamin D and Microbiota: Is There a Link with Allergies?

There is increasing recognition of the importance of both the microbiome and vitamin D in states of health and disease. Microbiome studies have already demonstrated unique microbial patterns in systemic autoimmune diseases such as inflammatory bowel disease, rheumatoid arthritis, and systemic lupus erythematosus. Dysbiosis also seems to be associated with allergies, in particular asthma, atopic dermatitis, and food allergy. Even though the effect of vitamin D supplementation on these pathologies is still unknown, vitamin D deficiency deeply influences the microbiome by altering the microbiome composition and the integrity of the gut epithelial barrier. It also influences the immune system mainly through the vitamin D receptor (VDR). In this review, we summarize the influence of the microbiome and vitamin D on the immune system with a particular focus on allergic diseases and we discuss the necessity of further studies on the use of probiotics and of a correct intake of vitamin D.     

Glass-ceramic composites for high-power white-light-emitting diodes

In this paper we report on the study of sintered ceramic composites based on a low melting glass in which ZnO nanocrystals and commercial YAG:Ce³⁺ phosphor are embedded. A low T_g is necessary to avoid high temperature sintering which can damage the optical properties of the embedded phosphor, while ZnO is introduced to increase the thermal conductivity of the system. The compositions have been optimized in terms of stability, sintering efficiency and thermal conductivity. Selected samples were optically characterized using a GaN high power multimode 450 nm Laser Diode, with a maximum output power of 1.6 W at 1.5 A.     

Nutritional metabonomics: an approach to promote personalized health and wellness

Nutritional research has emerged in the last century from the study of nutrients as a means of nourishment to the general population to the quest for wellness improvement through specific food components. Advances in nutrigenomics technologies have allowed nutrition scientists to be for the first time at the forefront of nutritional research. Such advances have given them the ability to discern new vital scientific discoveries specifically for the development of new tailored dietary patterns. In this, nutritional metabonomics has rapidly evolved into a very powerful bioanalytical tool able to assess multi-parametric metabolic responses of living organisms to specific dietary interventions. Nutritional metabonomics therefore provides a systematic approach through the comprehensive analysis of metabolites aiming today at the quest for homeostatic balance which is dependent not only on the host but also on the crucial metabolic interactions with microbial symbionts.     

Oxidative stability of polyunsaturated fatty acids: effect of squalene

The propensity of polyunsaturated fatty acids (PUFAs) to undergo oxidation plays an important role in the integrity of biological membrane and lipid containing foods. The ability of squalene (SQ), a naturally occurring dehydrotriterpene present in animal and plant tissues, to protect linoleic, linolenic, arachidonic and docosahexaenoic acids against temperature‐dependent autoxidation and UVA (ultraviolet A, 320‐380 nm) mediated oxidation was assessed. The oxidation of PUFAs was protected in varying degrees, with highest protection observed for linolenic, arachidonic and docosahexaenoic acids. Linoleic acid was less protected. At a molar ratio of 7:1 (PUFA:SQ) the inhibition of the oxidation process was 22% in the presence of linoleic acid and about 50% in presence of the other PUFAs tested. The different protection exerted by SQ against PUFAs with different degrees of unsaturation may be accounted for by the higher stability of octadecadienoic acid hydroperoxide isomers compared with respective PUFA hydroperoxides. Observing mild UVA‐mediated oxidation and the temperature‐dependent autoxidation reactions we found similarities in the oxidation pattern and the protection exerted by SQ. These findings suggest that the reaction of autoxidation is predominant and SQ acts mainly as peroxyl radical scavenger.     

Ionophore Ability of Carnosine and Its Trehalose Conjugate Assists Copper Signal in Triggering Brain-Derived Neurotrophic Factor and Vascular Endothelial Growth Factor Activation In Vitro

l-carnosine (β-alanyl-l-histidine) (Car hereafter) is a natural dipeptide widely distributed in mammalian tissues and reaching high concentrations (0.7–2.0 mM) in the brain. The molecular features of the dipeptide underlie the antioxidant, anti-aggregating and metal chelating ability showed in a large number of physiological effects, while the biological mechanisms involved in the protective role found against several diseases cannot be explained on the basis of the above-mentioned properties alone, requiring further research efforts. It has been reported that l-carnosine increases the secretion and expression of various neurotrophic factors and affects copper homeostasis in nervous cells inducing Cu cellular uptake in keeping with the key metal-sensing system. Having in mind this l-carnosine ability, here we report the copper-binding and ionophore ability of l-carnosine to activate tyrosine kinase cascade pathways in PC12 cells and stimulate the expression of BDNF. Furthermore, the study was extended to verify the ability of the dipeptide to favor copper signaling inducing the expression of VEGF. Being aware that the potential protective action of l-carnosine is drastically hampered by its hydrolysis, we also report on the behavior of a conjugate of l-carnosine with trehalose that blocks the carnosinase degradative activity. Overall, our findings describe a copper tuning effect on the ability of l-carnosine and, particularly its conjugate, to activate tyrosine kinase cascade pathways.