Crystal structure and optical characterization of a new hybrid compound, C6H9N2FeCl4, with large dielectric constants for field-effect transistors

Due to remarkable dielectric features, such as a large dielectric constant, strong electrical conductivity, high capacitance, and low dielectric loss, hybrid materials have lately seen a huge number of applications in the field of optoelectronics. These are critical characteristics that qualify the performance of optoelectronic devices, particularly field-effect transistor components (FETs). Here, the hybrid compound 2-amino-5-picoline tetrachloroferrate(iii) (2A5PFeCl₄) was synthesised by using the slow evaporation solution growth method at room temperature. Structural, optical, and dielectric properties have been investigated. The 2A5PFeCl₄ compound crystallises in the monoclinic system (P2₁/c space group). Its structure can be described as a successive layering of inorganic and organic parts. [FeCl₄]^- tetrahedral anions and 2-amino-5-picolinium cations are connected by N-H⋯Cl and C-H⋯Cl hydrogen bonds. The optical absorption measurement confirms the semiconductor nature with a band gap of around 2.47 eV. Additionally, the structural and electronic properties of the title compound have been investigated theoretically through DFT calculations. At low frequencies, this material has significant dielectric constants (ε ∼10⁶). Furthermore, the high electrical conductivity, low dielectric loss at high frequencies, and high capacitance show that this new material has great dielectric potential in FET technologies. Due to their high permittivity, these compounds can be employed as gate dielectrics.

Hydrogel foams from liquid foam templates: Properties and optimisation

Hydrogel foams are an important sub-class of macroporous hydrogels. They are commonly obtained by integrating closely-packed gas bubbles of 10-1000 μm into a continuous hydrogel network, leading to gas volume fractions of more than 70% in the wet state and close to 100% in the dried state. The resulting wet or dried three-dimensional architectures provide hydrogel foams with a wide range of useful properties, including very low densities, excellent absorption properties, a large surface-to-volume ratio or tuneable mechanical properties. At the same time, the hydrogel may provide biodegradability, bioabsorption, antifungal or antibacterial activity, or controlled drug delivery. The combination of these properties are increasingly exploited for a wide range of applications, including the biomedical, cosmetic or food sector. The successful formulation of a hydrogel foam from an initially liquid foam template raises many challenging scientific and technical questions at the interface of hydrogel and foam research. Goal of this review is to provide an overview of the key notions which need to be mastered and of the state of the art of this rapidly evolving field at the interface between chemistry and physics.

Structural features and morphology of titanium dioxide–bismuth vanadate heterojunctions

Titanium dioxide TiO2 (TO) and bismuth vanadate BiVO4 (BVO) are promising photoactive semiconducting oxides for heterogeneous photocatalysis devoted to water treatment, pollutant degradation and water splitting processes.

Perinatal deficiency in dietary omega-3 fatty acids potentiates sucrose reward and diet-induced obesity in mice

Insufficient dietary intake of essential omega-3 polyunsaturated fatty acids (N-3), especially during critical stages of development, is well-associated with negative neurological and metabolic consequences. The increased availability and intake of foods rich in saturated fat coincides with reduced N-3 consumption, yet how N-3 dietary deficiency during perinatal development modulates motivation for palatable food and interacts with a high-fat diet to affect body weight and emotional states is not clear. Pregnant C57Bl6 mice and pups were subjected to diets either deficient or adequate (control) in N-3 until postnatal day 21. Adult male N-3 deficient or control offspring were tested in a progressive ratio operant task for sucrose motivated behavior or given prolonged access to a saturated high-fat diet or chow followed by measures of energy balance and anxiety-like behavior in the elevated-plus maze and open field test. Brain fatty acid profiles were measured via gas chromatography mass spectrometry. Perinatal dietary N-3 deficiency lowered brain N-3 levels, augmented the rewarding effects of sucrose, heightened diet-induced weight gain and fat mass accumulation and diminished spontaneous physical activity. Finally, perinatal N-3 deficiency increased anxiety-like behaviour independent of diet in the open field but not in the elevated-plus maze test. Insufficient dietary N-3 during critical periods of developmental can amplify the obesogenic effects of saturated fat intake, enhance motivated behaviour for palatable foods and may elicit negative emotional states that can perpetuate overeating and obesity.

Central Agonism of GPR120 Acutely Inhibits Food Intake and Food Reward and Chronically Suppresses Anxiety-Like Behavior in Mice

BACKGROUND

GPR120 (FFAR4) is a G-protein coupled receptor implicated in the development of obesity and the antiinflammatory and insulin-sensitizing effects of omega-3 (ω-3) polyunsaturated fatty acids. Increasing central ω-3 polyunsaturated fatty acid levels has been shown to have both anorectic and anxiolytic actions. Despite the strong clinical interest in GPR120, its role in the brain is largely unknown, and thus we sought to determine the impact of central GPR120 pharmacological activation on energy balance, food reward, and anxiety-like behavior.

METHODS

Male C57Bl/6 mice with intracerebroventricular cannulae received a single injection (0.1 or 1 µM) or continuous 2-week infusion (1 µM/d; mini-pump) of a GPR120 agonist or vehicle. Free-feeding intake, operant lever-pressing for palatable food, energy expenditure (indirect calorimetry), and body weight were measured. GPR120 mRNA expression was measured in pertinent brain areas. Anxiety-like behavior was assessed in the elevated-plus maze and open field test.

RESULTS

GPR120 agonist injections substantially reduced chow intake during 4 hours postinjection, suppressed the rewarding effects of high-fat/-sugar food, and blunted approach-avoidance behavior in the open field. Conversely, prolonged central GPR120 agonist infusions reduced anxiety-like behavior in the elevated-plus maze and open field, yet failed to affect free-feeding intake, energy expenditure, and body weight on a high-fat diet.

CONCLUSION

Acute reductions in food intake and food reward suggest that GPR120 could mediate the effects of central ω-3 polyunsaturated fatty acids to inhibit appetite. The anxiolytic effect elicited by GPR120 agonist infusions favors the testing of compounds that can enter the brain to activate GPR120 for the mitigation of anxiety.

Influence of the cation size on the second harmonic generation response of chiral A(VO2)2(PO4)·3H2O (A = K+, NH4+ and Rb+)

Second harmonic generation responses of new chiral vanadium phosphate materials were shown to strongly increase upon contraction of the structure.