Controlled biomineralization of magnetite (Fe₃O₄) by <i>Magnetospirillum gryphiswaldense</i>

Results from a study of the chemical composition and micro-structural characteristics of bacterial magnetosomes extracted from the magnetotactic bacterial strain Magnetospirillum gryphiswaldense are presented here. Using high-resolution transmission electron microscopy combined with selected-area electron diffraction and energy dispersive X-ray microanalysis, biogenic magnetite particles isolated from mature cultures were analysed for variations in crystallinity and particle size, as well as chain character and length. The analysed crystals showed a narrow size range (∼14-67 nm) with an average diameter of 46±6.8 nm, cuboctahedral morphologies and typical Gamma type crystal size distributions. The magnetite particles exhibited a high chemical purity (exclusively Fe3O4) and the majority fall within the single-magnetic-domain range

Hundredfold Enhancement of Light Emission via Defect Control in Monolayer Transition-Metal Dichalcogenides

Two dimensional (2D) transition-metal dichalcogenide (TMD) based semiconductors have generated intense recent interest due to their novel optical and electronic properties, and potential for applications. In this work, we characterize the atomic and electronic nature of intrinsic point defects found in single crystals of these materials synthesized by two different methods - chemical vapor transport and self-flux growth. Using a combination of scanning tunneling microscopy (STM) and scanning transmission electron microscopy (STEM), we show that the two major intrinsic defects in these materials are metal vacancies and chalcogen antisites. We show that by control of the synthetic conditions, we can reduce the defect concentration from above $10^{13} /cm^2$ to below $10^{11} /cm^2$. Because these point defects act as centers for non-radiative recombination of excitons, this improvement in material quality leads to a hundred-fold increase in the radiative recombination efficiency

Vegetable Substitutes Waxes

Natural vegetable waxes (esters of monocarboxylic fatty acid with primary monocarboxylic fatty alcohols, both saturated with linear hydrocarbonated chains) widespread in composition of horticultural products, with a major role in their physiology as a barrier to controlled transfer of water and other metabolites. Extruded products can be found on the foliar surface of fruits (pruine, suberine, cutine, etc.) where they exercise a protective function. The range constantly ascending to the large scale application as a film requires the diversification of the graded range by accessing the synthetic substitutes that requires toxicity demands and also, thermal or mass transfer performances. Polyoxyethylene chains with variable oligomerisation degree grefted with alcohols (phenols) with medium hydrocarbonate chain (C8, C9) can be esterified with fatty acids (C16, C18) saturated and / or polyunsaturated obtained through the ecological integrated recovery of seed material from tomatoes processing [C14(0Δ) (6,34%); C16(0Δ) (31,6%); C18(0Δ) (21,15%); C18 (1Δ) (40,81%)] grown in areas from west of Romania. Lipidic fraction was processed by solid/liquid repeated extraction with petroleum ether (p.f.=40–60°C) (Soxhlet method) and classic analytical evaluated (refractive index, specific weight, iodine, saponification index) and gaschromatographic (column). "Homogeneous" polyoxyethylene chains with medium/large oligomerisation degree (n=3,9,18) processed by the Williamson method "step by step" from dyethyleneglycol, further grafted to 2–ethyl–hexyl alcohol respectively nonylphenol, were purified and characterized chemically and physical - chemical (colloidal)

Perturbation Mappings in Polynomiography

In the paper, a modification of rendering algorithm of polynomiograph is presented. Polynomiography is a method of visualization of complex polynomial root finding process and it has applications among other things in aesthetic pattern generation. The proposed modification is based on a perturbation mapping, which is added in the iteration process of the root finding method. The use of the perturbation mapping alters the shape of the polynomiograph, obtaining in this way new and diverse patterns. The results from the paper can further enrich the functionality of the existing polynomiography software