Solid-State Dispersions of Platinum in the SnO2 and Fe2O3 Nanomaterials.

The dispersion of platinum (Pt) on metal oxide supports is important for catalytic and gas sensing applications. In this work, we used mechanochemical dispersion and compatible Fe(II) acetate, Sn(II) acetate and Pt(II) acetylacetonate powders to better disperse Pt in Fe2O3 and SnO2. The dispersion of platinum in SnO2 is significantly different from the dispersion of Pt over Fe2O3. Electron microscopy has shown that the elements Sn, O and Pt are homogeneously dispersed in α-SnO2 (cassiterite), indicating the formation of a (Pt,Sn)O2 solid solution. In contrast, platinum is dispersed in α-Fe2O3 (hematite) mainly in the form of isolated Pt nanoparticles despite the oxidative conditions during annealing. The size of the dispersed Pt nanoparticles over α-Fe2O3 can be controlled by changing the experimental conditions and is set to 2.2, 1.2 and 0.8 nm. The rather different Pt dispersion in α-SnO2 and α-Fe2O3 is due to the fact that Pt4+ can be stabilized in the α-SnO2 structure by replacing Sn4+ with Pt4+ in the crystal lattice, while the substitution of Fe3+ with Pt4+ is unfavorable and Pt4+ is mainly expelled from the lattice at the surface of α-Fe2O3 to form isolated platinum nanoparticles.

Nanostructured Silicon as Potential Anode Material for Li-Ion Batteries.

Commercial micrometer silicon (Si) powder was investigated as a potential anode material for lithium ion (Li-ion) batteries. The characterization of this powder showed the mean particle size of approx.75.2 nm, BET surface area of 10.6 m2/g and average pore size of 0.56 nm. Its band gap was estimated to 1.35 eV as determined using UV-Vis diffuse reflectance spectra. In order to increase the surface area and porosity which is important for Li-ion batteries, the starting Si powder was ball-milled and threatened by metal-assisted chemical etching. The mechanochemical treatment resulted in decrease of the particle size from 75 nm to 29 nm, an increase of the BET surface area and average pore size to 16.7 m2/g and 1.26 nm, respectively, and broadening of the X-ray powder diffraction (XRD) lines. The XRD patterns of silver metal-assisted chemical etching (MACE) sample showed strong and narrow diffraction lines typical for powder silicon and low-intensity diffraction lines typical for silver. The metal-assisted chemical etching of starting Si material resulted in a decrease of surface area to 7.3 m2/g and an increase of the average pore size to 3.44 nm. These three materials were used as the anode material in lithium-ion cells, and their electrochemical properties were investigated by cyclic voltammetry and galvanostatic charge-discharge cycles. The enhanced electrochemical performance of the sample prepared by MACE is attributed to increase in pore size, which are large enough for easy lithiation. These are the positive aspects of the application of MACE in the development of an anode material for Li-ion batteries.

Depression and Heart Diseases: Leading Health Problems.

Depression is the most common psychiatric disorder in the world population and the most frequent mental disorder in a primary health care. Unrecognized and untreated depression is associated with a poor outcome of treated chronic diseases which co-exist with depression. Depression and cardiovascular diseases are bidirectional related conditions, risks are for each other, and they often co-exist. Depression is a common disorder in cardiovascular patients with a prevalence of 20% to 45%, which is much more frequent than in the general population. In cardiac patients with acute myocardial infarction, depression occurs three times more often than in the general population. Depression has a direct effect on the pathophysiological changes of various organ systems, changing the values of blood pressure, heart rate, vasomotor tone, vascular resistance, blood viscosity and plasma volume. The potential mechanism for developing heart disease in depressed patients includes hypothalamic-pituitary-adrenal gland dysfunction, increased proinflammatory and prothrombotic factor activity, reduced omega-3 fatty acids, reduced heart rate variability, smoking, physical inactivity, reduced mood, self-esteem and self-efficacy.