Ground level ozone (O3) associated with radon (222Rn) and particulate matter (PM) concentrations in Bucharest metropolitan area and adverse health effects

The aim of this paper is to contribute with new information in the application of ground based radon (²²²Rn) observations to atmospheric research, namely its relation with air pollution due to ground-level ozone (O₃) and particle matter in two size fractions (PM10 and PM2.5) for Bucharest metropolitan area in Romania. During January 1–December 31, 2011, ground levels of radon, ozone and particulate matter (PM) have been continuously monitored in synergy with the main meteorological parameters (air temperature, humidity and pressure), and daily global air quality indices. A systematic analysis of surface ozone observations of ground level radon, ozone and PM is presented. Observational results indicate the following yearly daily mean ground level concentrations: 40.26 ± 7.54 Bq/m³ for radon, 90.51 μg/m³ for ozone, 35.96 μg/m³ for PM2.5, and 40.91 μg/m³ for PM10. The assessment of the results showed the influence of local and meteorological conditions on the daily mean radon, ozone and PM concentrations. However, in densely populated metropolitan area of Bucharest the mean daily values of ozone, PM2.5, PM10, and attached ²²²Rn are sometimes higher than European Community limit values leading to serious public concern during the last years. Due to the high risk of increased levels of O₃, PM2.5, PM10, and attached ²²²Rn on human health respiratory function (especially for children and older persons), and urban green, the results are very useful for atmospheric, radiological protection, epidemiological and environmental studies.     

Synthesis of Porous,Hollow Metal MCO3 (M=Mn,Co, Ca) Microstructures and Adsorption Properties Thereof

Porous, hollow metal carbonate microstructures show many unique properties, and are attractive for various applications. Herein, we report the first demonstration of a general strategy to synthesize hollow metal carbonate structures, including porous MnCO₃ hollow cubics, porous CoCO₃ hollow rhombuses and porous CaCO₃ hollow capsules. For example, the porous, hollow MnCO₃ microcubes show larger Brunauer–Emmett–Teller (BET) surface areas of 359.5 m² g^?1, which is much larger than that of solid MnCO₃ microcubics (i.e., 12.03 m² g^?1). As a proof of concept, these porous MnCO₃ hollow microcubes were applied to water treatment and exhibited an excellent ability to remove organic pollutants in waste water owing to their hollow structure and large specific surface area.     

Microwave assisted extraction of essential oils from enzymatically pretreated lavender (<Emphasis Type="Italic">Lavandula angustifolia</Emphasis> Miller)

In this study, microwave assisted a hydrodistillation process (MWHD) of essential oils from lavender (Lavandula angustifolia Miller) was investigated. In order to examine any potential differences in essential oil extraction, the lavender flowers underwent enzymatic pretreatment.A 2³ factorial design of experiments, combined with statistical methods of data analysis were used to optimize enzymatic pretreatment and to evaluate the influence of major variables (enzyme concentration, temperature and pH) on the performance of the microwave assisted extraction.Under optimal conditions, an extraction yield of 24 mg oil g^?1 substrate was achieved (an increase by approximately 25% in comparison with the classic extraction conditions of conventional hydrodistillation).The main compounds of the essential oils obtained were analyzed and identified by gas chromatography coupled to mass spectrometry (GC-MS). Analyzing the data obtained indicated that the content of main compounds (linalool and linalyl acetate ? 73%) was greater than that obtained by conventional extraction (67%).

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Silver delafossite oxides

A single-step, low-temperature (<210 degrees C) and -pressure (<20 atm) hydrothermal method has been developed to synthesize a series of silver delafossites, AgBO2 (B = Al, Ga, Sc, and In). Experimental and computational studies were performed to understand the optical and electric properties of these silver delafossites, including the first in-depth study of AgAlO2 and AgScO2. Their properties were examined as a function of the trivalent cation radius and compared to those of copper delafossites to elucidate the role of both the A- and B-site cations. While optical band gaps for silver delafossites were larger and visible light absorption was lower than values previously reported for polycrystalline powder samples of copper delafossites, the conductivities of silver delafossites are similar or lower. Electronic structure calculations indicate that these properties are due to the scarcity of silver 4d states just below the valence band maximum.     

Self-assembly properties of some chiral N-palmitoyl amino acid surfactants in aqueous solution

Various chiral N-palmitoyl amino acid surfactants (AAS) derived from methionine, proline, leucine, threonine, phenylalanine and phenylglycine were prepared and converted to their sodium salt. The properties of the aggregates formed in aqueous solution were studied for both the optically-active compounds and their racemic mixture. Characterization was made by surface tensiometry, fluorimetry, dynamic light scattering, circular dichroism (CD) and transmission electron microscopy. It appeared that most of the AAS studied in this work spontaneously formed different types of aggregates, including micrometer-sized aggregates. No significant difference could be found between the critical aggregation concentration (cac) value of pure enantiomers and that of the racemic forms. CD spectra did not reveal any aggregation-induced chirality.     

Solar and supplemental UV-B radiation effects in lemon peel UV-B-absorbing compound content-seasonal variations

Effects of solar and supplemental UV-B radiation on UV-B-absorbing compounds and malondialdehyde (MDA) accumulations in the peel of lemons collected in summer and winter were analyzed. UV-B-absorbing compounds were higher in flavedo than in albedo tissue in both seasons; however, the highest values were observed in summer. These compounds were also higher in outer than in inner flavedo surface. Lemons were categorized as sun-, semisun- and shaded-lemon according to localization inside the tree canopy. Depending on-tree localization UV-B-absorbing compounds were higher in flavedo of sun-lemon than in semisun- and shaded-lemon. Supplementary UV-B radiation (22 kJ m(-2) day(-1) UV-BBE) induced UV-B-absorbing compound synthesis in on-tree and postharvest lemons. Two minutes of supplemental UV-B irradiation in summer lemons produced a strong increment (300%) of UV-B-absorbing compound content, whereas in winter lemons a slight increase (30%) was observed only after 3 min of irradiation. By contrast, UV-B-absorbing compound accumulation was not observed in albedo. MDA accumulation showed approximately a similar trend of UV-B-absorbing compounds. According to our results, solar UV-B was not required for UV-B-absorbing compound accumulation in lemon peel. Relationships between UV-B-absorbing compounds, MDA, reactive oxygen species and pathogen protection are also discussed.     

Platinum-DNA Origami Hybrid Structures in Concentrated Hydrogen Peroxide

The DNA origami technique allows fast and large-scale production of DNA nanostructures that stand out with an accurate addressability of their anchor points. This enables the precise organization of guest molecules on the surfaces and results in diverse functionalities. However, the compatibility of DNA origami structures with catalytically active matter, a promising pathway to realize autonomous DNA machines, has so far been tested only in the context of bio-enzymatic activity, but not in chemically harsh reaction conditions. The latter are often required for catalytic processes involving high-energy fuels. Here, we provide proof-of-concept data showing that DNA origami structures are stable in 5 % hydrogen peroxide solutions over the course of at least three days. We report a protocol to couple these to platinum nanoparticles and show catalytic activity of the hybrid structures. We suggest that the presented hybrid structures are suitable to realize catalytic nanomachines combined with precisely engineered DNA nanostructures.     

Serine hydroxymethyl transferase from Streptococcus thermophilus and L-threonine aldolase from Escherichia coli as stereocomplementary biocatalysts for the synthesis of beta-hydroxy-alpha,omega-diamino acid derivatives

A novel serine hydroxymethyl transferase from Streptococcus thermophilus (SHMT) and a L-threonine aldolase from Escherichia coli (LTA) were used as stereocomplementary biocatalysts for the aldol addition of glycine to N-Cbz amino aldehydes and benzyloxyacetaldehyde (Cbz=benzyloxycarbonyl). Both threonine aldolases were classified as low-specific L-allo-threonine aldolases, and by manipulating reaction parameters, such as temperature, glycine concentration, and reaction media, SHMT yielded exclusively L-erythro diastereomers in 34-60 % conversion, whereas LTA gave L-threo diastereomers in 30:70 to 16:84 diastereomeric ratios and with 40-68 % conversion to product. SHMT is among the most stereoselective L-threonine aldolases described. This is due, among other things, to its activity-temperature dependence: at 4 degrees C SHMT has high synthetic activity but negligible retroaldol activity on L-threonine. Thus, the kinetic L-erythro isomer was largely favored and the reactions were virtually irreversible, highly stereoselective, and in turn, gave excellent conversion. It was also found that treatment of the prepared N-Cbz-gamma-amino-beta-hydroxy-alpha-amino acid derivatives with potassium hydroxide (1 m) resulted in the spontaneous formation of 2-oxazolidinone derivatives of the beta-hydroxyl and gamma-amino groups in quantitative yield. This reaction might be useful for further chemical manipulations of the products.     

HeI photoelectron and valence synchrotron photoionization studies of the thioester molecule CH3C(O)SCH3: evidence of vibronic structure

One of the simplest thioester molecules, S-methyl thioacetate, CH 3C(O)SCH 3, has been investigated by HeI photoelectron spectroscopy (PES) and valence photoionization studies using synchrotron radiation in the same energy range. In the second series of experiments, total ion yield (TIY), photoelectron photoion coincidence (PEPICO), and partial ion yield (PIY) spectra were recorded. It was found that the photodissociation behavior of CH 3C(O)SCH 3 can be divided into three well-defined energy regions. Vibronic structure was observed in the valence synchrotron photoionization process, being associated with wavenumbers of 912, 671, 1288, 1690, and 1409 cm (-1) for the bands at 12.82, 13.27, 15.66, 15.72, and 17.42 eV, respectively. Evaluation of the PE spectrum in concert with the synchrotron photoionization measurements and complemented by high-level ab initio calculations thus provides unusually detailed insights into the valence ionization processes of this molecule.