Statistical anisotropy from vector curvaton in D-brane inflation

We investigate the possibility of embedding the vector curvaton paradigm in D-brane models of inflation in type IIB string theory in a simple toy model. The vector curvaton is identified with the U(1)$U(1)$ gauge field that lives on the world volume of a D3-brane, which may be stationary or undergoing general motion in the internal space. The dilaton is considered as a spectator field which modulates the evolution of the vector field. In this set-up, the vector curvaton is able to generate measurable statistical anisotropy in the spectrum and bispectrum of the curvature perturbation assuming that the dilaton evolves as e^−?∝a²$e^{-?}\propto a^2$ where a(t)$a(t)$ is the scale factor. Our work constitutes a first step towards exploring how such distinctive features may arise from the presence of several light fields that naturally appear in string theory models of cosmology.     

Quantitative determination of ochratoxin A in vegetable foods

Summary A simple method for the quantitative determination of ochratoxin A (OA) in rice and other vegetable foods (oatmeal, coconut flakes and peas) is described. This procedure implies an acetonitrile-4% KCl -6N HCl (88+10+2) extraction of the acidic OA, subsequent twodimensional thin-layer chromatography (TLC) and detection by fluorescence after exposure to ammonia fumes (excitation at 340 nm; emission at 475 nm). The quantitative detection limit for OA in rice or coconut flakes is 2.4–4 g/kg and the recovery is 96%. For oatmeal and peas the detection limit is only 20 g/kg because of the interference by other metabolites.

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Quantitative Bestimmung von Ochratoxin A in pflanzlichen Nahrungsmitteln

Zusammenfassung Eine einfache Methode zur quantitativen Bestimmung von Ochratoxin A (OA) in Reis und anderen pflanzlichen Nahrungsmitteln (Haferflocken, Kokosflocken, und Erbsen) wird beschrieben. Zur Extraktion wird Acetonitril-4% KCl -6N HCl (88+10+2) benutzt. Nach der Aufbereitung wird eine Auftrennung durch zweidimensionale DC-Trennung (TLC) vorgenommen. Die quantitative Bestimmung erfolgt durch Fluorescenzphotometrie nach Behandlung der Platten mit gasförmigem Ammoniak (Anregung bei 340 nm, Emission bei 475 nm). Die quantitative Bestimmungsgrenze in Reis oder Kokosflocken beträgt 2,4–4 g/kg und die Wiederfindung (Reis) 96%. Für Haferflocken und Erbsen wurde wegen des Störeffektes durch andere Metaboliten nur eine quantitative Bestimmungsgrenze von 20 g/kg erreicht.

     

Absence of gauge-invariant functionals on spectral C*-algebras

We show that Arveson??s spectral C*-algebra C*(E) of an arbitrary product system E?=?{E(t)} _t>0 admits no non-zero gauge-invariant positive functionals.     

Improving pulse sequences for 3D DOSY: COSY-IDOSY

An improved pulse sequence for measuring diffusion-ordered COSY spectra is achieved by incorporating the diffusion encoding directly into the evolution and detection periods of a gradient-enhanced COSY sequence, giving improved sensitivity and a 32-fold reduction in minimum experiment time.     

Entanglement dynamics in open two-qubit systems via diffusive quantum trajectories

We use quantum diffusive trajectories to prove that the time evolution of two-qubit entanglement under spontaneous emission can be fully characterized by optimal continuous monitoring. We analytically determine this optimal unraveling and derive a deterministic evolution equation for the system's concurrence. Furthermore, we propose an experiment to monitor the entanglement dynamics in bipartite two-level systems and to determine the disentanglement time from a single trajectory.     

Polyphenolic profile by FIA/ESI/IT/MSn and antioxidant capacity of the ethanolic extract from the barks of Maytenus cajalbanica (Borhidi & O. Muñiz) Borhidi & O. Muñiz

Abstract

Medium and high polarity extracts from Maytenus species are known to contain polyphenolic compounds such as proanthocyanidins. The high polarity and structural complexity of these compounds make very difficult their isolation even by modern chromatographic techniques. Maytenus cajalbanica (Borhidi & O. Muñiz) Borhidi & O. Muñiz is endemic from Cuba. So far, there are reports neither of phytochemical work nor of biological evaluation of extracts from this subspecies. The goal of this work is to determine the polyphenolic profile and the antioxidant capacity of the ethanolic extract from the barks of Maytenus cajalbanica. FIA/ESI/IT/MSⁿ analysis allowed the identification of 5 flavan-3-ol monomers, 33 proanthocyanidins, 2 free flavonoids and their respective glycosides as major compounds of the ethanolic extract, which showed a strong radical scavenging capacity and a significant ferric reduction power. FIA/ESI/IT/MSⁿ technique led the rapid, effective and sensitive determination of the polyphenolic profile of Maytenus cajalbanica without previous separation.     

In1.06Ho0.94Ge2O7: a thortveitite‐type compound

A new indium holmium digermanate, In_1.06Ho_0.94Ge₂O₇, with a thortveitite‐type structure, has been prepared as a polycrystalline powder material by high‐temperature solid‐state reaction. This new compound crystallizes in the monoclinic system (space group C2/c, No. 15). The structure was characterized by Rietveld refinement of powder laboratory X‐ray diffraction data. The In³⁺ and Ho³⁺ cations occupy the same octahedral site, forming a hexagonal arrangement on the ab plane. In their turn, the hexagonal arrangements of (In/Ho)O₆ octahedral layers are held together by sheets of isolated diortho groups comprised of double tetrahedra sharing a common vertex. In this compound, the Ge₂O₇ diortho groups lose the ideal D_3d point symmetry and also the C_2h point symmetry present in the thortveitite diortho groups. The Ge—O—Ge angle bridging the diortho groups is 160.2 (3)°, compared with 180.0° for Si—O—Si in thortveitite (Sc₂Si₂O₇). The characteristic mirror plane in the thortveitite space group (C2/m, No. 12) is not present in this new thortveitite‐type compound and the diortho groups lose the C_2h point symmetry, reducing to C₂.     

Natural UV-Screening Mechanisms of Norway Spruce (Picea abies [L.] Karst.) Neediest

Abstract— Ultraviolet-light screening potential of Norway spruce (Picea abies [L.] Karst.) needles was investigated by UV-spectroscopic, microscopic, fluorescence spectroscopic techniques as well as by HPLC, mass spectrometry and NMR spectroscopy. Results showed four potential barriers of UV screening by Norway spruce needles: (1) UV-light screening via reflectance of UV/violet light by epidermis, (2) UV-light screening via reduction of transmission of UV light by special anatomical arrangement of the epidermal cells containing the UV-screening allomelanins as well as by the light-reflecting hyaline hypodermal cells, (3) conversion of UV light by epidermis into photosynthetically active radiation (PAR; blue and red spectral bands) via fluorescence and (4) UV-light screening by absorption of UV light by UV-screening substances contained in the epidermis, whereby the latter was found to be the most important UV-screening mechanism. Staining of needle cross sections with Naturstoffreagenz A showed the localization of bound flavonoids and its derivatives in the cell walls of the outer epidermal cell layer as revealed by confocal laser scanning microscopy. By fluorescence spectroscopy and confocal laser scanning microscopy, the conversion of UVA light into PAR in the epidermis was related to various UV-screening substances contained in the epidermis. The methanol-soluble UV-absorbing substances were found to create novel UV-screening barrier zones: UVC, >200–253 nm; UVC/UVB, >253–300/303 nm; and UVB/UVA, >300–362/368 nm in epidermis as well as in mesophyll (±vascular bundles) tissues, suggesting the protective functions of epidermis for the underlying mesophyll as well as of mesophyll for the underlying vascular bundles. The following sequence of efficiency of UV-screening barrier zones of the methanol-soluble extracts of the needle epidermis and mesophyll (± vascular bundles) for various UV-spectral bands was detected: UVC screening at less than 265 nm > UVC screening at 265–280 nm > UVB screening at 280–320 nm > UVA screening at 280–320 nm, whereby the UV screening at 280–320 nm was suggested as the most relevant barrier against enhanced UVB radiation. A blend of various UV-screening substances occurred in the methanol-soluble fractions of needle epidermis, whereby p-hydroxybenzoic acid 4-O-β-D-glucopyranoside, picein, (+)-catechin, p-hydroxyacetophenone, benzoic acid and astragalin were identified as UVC/UVB-screening substances; picein, (+)-catechin, astringin, p-hydroxyacetophenone and astragalin(s) as UVB-screening substances and astragalin(s) as UVA/B-screening substances. Alkaline hydrolysis of methanol-insoluble epidermal cell wall fractions released p-coumaric acid, ferulic acid and as-tragalin(s) as major UVB-screening substances. Loss of vitality of Norway spruce trees (forest decline disease) led to a significant reduction of UVB (315 nm)-screening ability of methanol-soluble fractions from epidermis, mesophyll (±vascular bundles) and whole needles. The HPLC analysis showed that the loss of vitality is due to a reduction in accumulation of UVB-absorbing substances, mainly picein, (+)-catechin, isorhapontin and astragalin(s) in the epidermis of needles from the second needle year in accordance with the detected loss of UVB-screening ability. It is concluded that the natural UV-screening mechanisms of Norway spruce needles are highly complex but mainly actively mediated by the ability of methanol-soluble UV-absorbing substances to form variable UVB-AJVA-screening barrier zones and passively by the ability of epidermal cell wall-bound UV-screening substances to screen UV light, whereby in the epidermis a conversion of excess UV light into PAR takes place.     

Can the provenance of the conflict minerals columbite and tantalite be ascertained by laser-induced breakdown spectroscopy?

Conflict minerals is a term applied to ores mined in conditions of armed conflict and human rights abuse. Niobium and tantalum are two rare metals whose primary natural occurrence is in the complex oxide minerals columbite and tantalite, the ore of which is commonly referred to as coltan. The illicit export of coltan ore from the Democratic Republic of the Congo is thought to be responsible for financing the ongoing civil conflicts in this region. Determining the chemical composition of an ore is one of the means of ascertaining its provenance. Laser-induced breakdown spectroscopy (LIBS) offers a means of rapidly distinguishing different geographic sources for a mineral because the LIBS plasma emission spectrum provides the complete chemical composition (i.e., “chemical fingerprint”) of any material in real time. To test this idea for columbite–tantalite, three sample sets were analyzed. Partial least squares discriminant analysis (PLSDA) allows correct sample-level geographic discrimination at a success rate exceeding 90%.