Preparation,Crystal Structure and Properties of Spirophosphoranes Derived from Hydroxycarboxylic Acid Azides

Abstract

Spirophosphoranes are produced by reaction of 2–phenyl–1,3,2–dioxaphospholane with both 2- and 3–hydroxycarboxylic acid azides, whereas 1–phenyl–phospholane yields spirophosphoranes only upon reaction with the former. The structures of two spirophosphoranes have been determined by X-ray analysis.     

Photoinduced dynamics of a cyanine dye: parallel pathways of non-radiative deactivation involving multiple excited-state twisted transients

Cyanine dyes are broadly used for fluorescence imaging and other photonic applications. 3,3′-Diethylthiacyanine (THIA) is a cyanine dye composed of two identical aromatic heterocyclic moieties linked with a single methine, –CH. The torsional degrees of freedom around the methine bonds provide routes for non-radiative decay, responsible for the inherently low fluorescence quantum yields. Using transient absorption spectroscopy, we determined that upon photoexcitation, the excited state relaxes along two parallel pathways producing three excited-state transients that undergo internal conversion to the ground state. The media viscosity impedes the molecular modes of ring rotation and preferentially affects one of the pathways of non-radiative decay, exerting a dominant effect on the emission properties of THIA. Concurrently, the polarity affects the energy of the transients involved in the decay pathways and further modulates the kinetics of non-radiative deactivation.     

Heat and moisture transfer in sol–gel treated cotton fabrics

Cotton fabrics have been treated by sol–gel processes in order to produce an inorganic coating on fibres, able to modify their thermal conductivity under an irradiating flow. To this aim, fabric specimens with different silica content have been tested following the ISO 6942 standard in order to establish the effect of the coating on coupled heat and moisture transfer through the cotton fibres. The collected results have been compared with those obtained by an optimized method using a cone calorimeter as the heating source. By this latter approach, it has been demonstrated that sol–gel cotton treated fabrics with high moisture uptake possess a significantly lower thermal conductivity with respect to cotton alone.     

2D difference gel electrophoresis reference map of a Fusarium graminearum nivalenol producing strain

Fusarium graminearum is widely studied as a model for toxin production among plant pathogenic fungi. A 2D DIGE reference map for the nivalenol‐producing strain 453 was established. Based on a whole protein extract, all reproducible spots were systematically picked and analyzed by MALDI‐TOF/TOF, leading to the identification of 1102 protein species. The obtained map contributes to the annotation of the genome by identifying previously nondescribed hypothetical proteins and will serve as a reference for future studies aiming at deciphering F. graminearum biology and chemotype diversity.     

The development of radioactive glass surrogates for fallout debris

The production of glass that emulates fallout is desired by the nuclear forensics community for training and measurement exercises. The composition of nuclear fallout is complex, with widely varying isotopic compositions (Fahey et al., Proc Natl Acad Sci USA 107(47):20207–20212, 2010; Bellucci et al., Anal Chem 85:7588–7593, 2013; Wallace et al., J Radioanal Nucl Chem, 2013; Belloni et al., J Environ Radioact 102:852–862, 2011; Freiling, Science 139:1058–1059, 1963; Science 133:1991–1999, 1961; Bunney and Sam Government Report: Naval Ordinance Laboratory, White Oak, 1971). As the gaseous cloud traverses from hotter to cooler regions of the atmosphere, the processes of condensation and nucleation entrain environmental materials, vaporized nuclear materials and fission products. The elemental and isotopic composition of the fission products is altered due to chemical fractionation (i.e. the fission product composition that would be expected from fission of the original nuclear material is altered by differences in condensation rates of the elements); the fallout may be enriched or depleted in volatile or refractory fission products. This paper describes preliminary work to synthesize, irradiate and fractionate the fission product content of irradiated particulate glass using a thermal distillation 2 h after irradiation. The glass was synthesized using a solution-based polymerization of tetraethyl orthosilicate. (Izrael, Radioactive fallout after nuclear explosions and accidents, 2002) Uranium was incorporated into the glass particulate at trace concentrations during polymerization. The particulate was subjected to a short thermal neutron irradiation then heated to 1,273 K approximately 2 h after the end of irradiation. Fission products of ^{133, 134, 135}I, ^{132, 134}Te, ¹³⁵Xe, ¹³⁸Cs and ^{91, 92}Sr were observed to be distilled from the particulate. The results of these preliminary studies are discussed.     

Hydrogen Peroxide Detection Using Prussian Blue-modified 3D Pyrolytic Carbon Microelectrodes

A highly sensitive amperometric Prussian blue-based hydrogen peroxide sensor was developed using 3D pyrolytic carbon microelectrodes. A 3D printed multielectrode electrochemical cell enabled simultaneous highly reproducible Prussian blue modification on multiple carbon electrodes. The effect of oxygen plasma pre-treatment and deposition time on Prussian blue electrodeposition was studied. The amperometric response of 2D and 3D sensors to the addition of hydrogen peroxide in μM and sub-μM concentrations in phosphate buffer was investigated. A high sensitivity comparable to flow injection systems and a detection limit of 0.16 μM was demonstrated with 3D pyrolytic carbon microelectrodes at stirred batch condition     

Reversible and Selective CO2 to HCO2− Electrocatalysis near the Thermodynamic Potential

Reversible catalysis is a hallmark of energy‐efficient chemical transformations, but can only be achieved if the changes in free energy of intermediate steps are minimized and the catalytic cycle is devoid of high transition‐state barriers. Using these criteria, we demonstrate reversible CO₂/HCO₂^? conversion catalyzed by [Pt(depe)₂]²⁺ (depe=1,2‐bis(diethylphosphino)ethane). Direct measurement of the free energies associated with each catalytic step correctly predicts a slight bias towards CO₂ reduction. We demonstrate how the experimentally measured free energy of each step directly contributes to the <50 mV overpotential. We also find that for CO₂ reduction, H₂ evolution is negligible and the Faradaic efficiency for HCO₂^? production is nearly quantitative. A free‐energy analysis reveals H₂ evolution is endergonic, providing a thermodynamic basis for highly selective CO₂ reduction.     

The Varietal Influence of Flavour Precursors from Grape Marc on Monoterpene and C13-Norisoprenoid Profiles in Wine as Determined by Membrane-Assisted Solvent Extraction (MASE) GC-MS

The winemaking by-product grape marc (syn. pomace) contains significant quantities of latent flavour in the form of flavour precursors which can be extracted and used to modulate the volatile composition of wine via chemical hydrolysis. Varietal differences in grapes are widely known with respect to their monoterpene content, and this work aimed to extend this knowledge into differences due to cultivar in volatiles derived from marc precursors following wine-like storage conditions. Marc extracts were produced from floral and non-floral grape lots on a laboratory-scale and from Muscat Gordo Blanco marc on a winery -scale, added to a base white wine for storage over five to six months, before being assessed using a newly developed membrane-assisted solvent extraction gas chromatography-mass spectrometry (GC-MS) method. The geraniol glucoside content of the marc extracts was higher than that of juices produced from each grape lot. In all wines with added marc extract from a floral variety, geraniol glucoside concentration increased by around 150–200%, with increases also observed for non-floral varieties. The relative volatile profile from extracts of the floral varieties was similar but had varied absolute concentrations. In summary, while varietally pure extracts would provide the greatest control over flavour outcomes when used in winemaking, aggregated marc parcels from floral cultivars may provide a mechanism to simplify the production logistics of latent flavour extracts for use in the wine sector.     

Extraction of plasmid DNA from Escherichia coli cell lysate in a thermoseparating aqueous two-phase system

The primary purification of a 6.1 kilo base pair (kbp) plasmid from a desalted alkaline lysate has been accomplished by a thermoseparating aqueous two-phase system [(50% ethylene oxide-50% propylene oxide)-Dextran T 500]. The partitioning of the different nucleic acids (plasmid DNA, RNA, genomic DNA) in the thermoseparating aqueous two-phase system was followed both qualitatively by agarose gel electrophoresis and quantitatively by analytical chromatography (size exclusion- and anion-exchange mode) and PicoGreen fluorescence analysis. The experimental results showed a complete recovery of the plasmid DNA to the top phase, while 80% of total RNA and 58% of total protein was discarded to the bottom phase. Moreover, a 3.8-fold volume reduction of the plasmid DNA solution was achieved. By using a final thermoseparating step, the EO50PO50 polymer could be efficiently recycled, resulting in plasmid solution containing less than 1% polymer. The developed thermoseparating aqueous two-phase system shows great potential for the large-scale processing of plasmid DNA.