380 research outputs found

    Newton-Cartan Gravity and Torsion

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    We compare the gauging of the Bargmann algebra, for the case of arbitrary torsion, with the result that one obtains from a null-reduction of General Relativity. Whereas the two procedures lead to the same result for Newton-Cartan geometry with arbitrary torsion, the null-reduction of the Einstein equations necessarily leads to Newton-Cartan gravity with zero torsion. We show, for three space-time dimensions, how Newton-Cartan gravity with arbitrary torsion can be obtained by starting from a Schroedinger field theory with dynamical exponent z=2 for a complex compensating scalar and next coupling this field theory to a z=2 Schroedinger geometry with arbitrary torsion. The latter theory can be obtained from either a gauging of the Schroedinger algebra, for arbitrary torsion, or from a null-reduction of conformal gravity.Comment: 21 page

    <i>S. japonicum</i> egg nodes visible in the submucosa.

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    <p>(A) The ascending colon and (B) the sigmoid colon.</p

    The diagram of the path in pursing medical treatment for the patient.

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    <p>The diagram of the path in pursing medical treatment for the patient.</p

    Nitrogen-Doping Enhanced Fluorescent Carbon Dots: Green Synthesis and Their Applications for Bioimaging and Label-Free Detection of Au<sup>3+</sup> Ions

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    Fluorescent carbon dots (CDs) hold great promise for a myriad applications due to their fascinating attributes. However, the development of CDs with high fluorescence quantum yield (QY) and unique surface property is still in its infancy. Herein, we report a simple and green strategy to produce water-soluble nitrogen-doped CDs (N-CDs) via the one-pot hydrothermal carbonization of the mixture of natural peach gum polysaccharide (PGP) and ethylenediamine. The resulting N-CDs exhibit a remarkably enhanced QY (28.46%) as compared with that of undoped CDs (5.31%). In addition, the N-CDs show stable fluorescence against ionic strength variation and pH change. Preliminary biological studies reveal that N-CDs possess low cytotoxicity and high fluorescent contrast in cells. Moreover, we present here for the first time that the obtained N-CDs can exhibit a fast and highly sensitive and selective fluorescence quenching effect toward Au<sup>3+</sup> ions. The detection limit can reach 6.4 × 10<sup>–8</sup> M, which compares favorably to other reported fluorescent probes. We have also demonstrated that the N-CDs can be employed to sense Au<sup>3+</sup> ions in real river water. Considering the easy synthetic process and excellent performance of the N-CDs, this investigation opens up new opportunities for preparing high-quality fluorescent CDs to meet the requirement of many applications

    Numbers of advanced schistosomiasis japonica in China.

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    <p>(A) In each province by 2008; (B) in each province by 2003 and new cases found from 2004 to 2008; and (C) the coverage rates of the aid-project in the cases at the levels of nation or province (Anhui) over 2004 to 2008.</p

    Identification of Oxidation Compounds of 1‑Stearoyl-2-linoleoyl-<i>sn</i>-glycero-3-phosphoethanolamine during Thermal Oxidation

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    Heat-induced oxidative modification of phosphatidylethanolamine molecular species as potential functional food components was investigated. 1-Stearoyl-2-linoleoyl-<i>sn</i>-glycero-3-phosphoethanolamine (SLPE) was chosen as a model. The optimal temperature for hydroperoxide formation was determined by mass spectrometry. The maximal level of formation of this compound was obtained at 125 °C. The structures of nonvolatile organic compounds (non-VOCs) were identified using liquid chromatography–electrospray ionization mass spectrometry combined with an acid treatment. Kinetics of formation of non-VOCs was monitored over time. Results showed that the level of the SLPE precursor rapidly decreased during thermal oxidation and oxygenated products, such as hydroxyl, oxo, or epoxy groups, were formed. The VOCs formed from oxidized SLPE were determined by headspace solid-phase microextraction followed by gas chromatography–mass spectrometry analysis. The result showed that a saturated methyl ketone (2-heptanone) was the most predominant VOC of SLPE. Kinetics indicated that the formation of VOCs was related not only to the decomposition of hydroperoxides but also to the further decomposition of non-VOCs

    Transfer Properties of Glycylglycine from Water to Aqueous NaNO<sub>3</sub>, NaClO<sub>4</sub>, and Na<sub>2</sub>SO<sub>4</sub> Solutions

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    Enthalpies of solution and densities of glycylglycine in aqueous solutions of NaNO<sub>3</sub>, NaClO<sub>4</sub>, and Na<sub>2</sub>SO<sub>4</sub> were measured at 298.15 K. Standard transfer enthalpies (Δ<sub>tr</sub><i>H</i><sup>0</sup>), standard transfer partial molar volume (Δ<sub>tr</sub><i>V</i><sub>ϕ</sub><sup>0</sup>), and hydration numbers (<i>N</i><sub>h</sub>) have been determined for glycylglycine. All of the Δ<sub>tr</sub><i>H</i><sup>0</sup> values are negative in the three salt solutions. The relative order of Δ<sub>tr</sub><i>H</i><sup>0</sup> in the same concentration of 1–1 type salts is NaNO<sub>3</sub> > NaClO<sub>4</sub>. The Δ<sub>tr</sub><i>H</i><sup>0</sup> in low concentration of Na<sub>2</sub>SO<sub>4</sub> solutions is between the corresponding values in NaNO<sub>3</sub> and NaClO<sub>4</sub> solutions. With increasing Na<sub>2</sub>SO<sub>4</sub> concentration, the Δ<sub>tr</sub><i>H</i><sup>0</sup> values exceed that in NaNO<sub>3</sub> solutions. The Δ<sub>tr</sub><i>V</i><sub>ϕ</sub><sup>0</sup> values are positive and vary in the sequence Na<sub>2</sub>SO<sub>4</sub> > NaNO<sub>3</sub> > NaClO<sub>4</sub>. The results were discussed in terms of various interactions

    Comparison of the Volatiles Formed by Oxidation of Phosphatidylcholine to Triglyceride in Model Systems

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    The oxidative stability of oleoyl and linoleoyl residues esterified in the form of triglyceride (TAG) and phosphatidylcholine (PC) during thermal treatment was investigated. Headspace solid-phase microextraction (HS-SPME) followed by gas chromatography–mass spectrometry (GC–MS) analysis was used to determine the volatile compounds from oxidized PL and TAG molecular species. The results showed that aldehydes were the major volatile oxidized compounds (VOCs) of 1-stearoyl-2-oleoyl-<i>sn</i>-glycero-3-phosphocholine (SOPC), 1-stearoyl-2-linoleoyl-<i>sn</i>-glycero-3-phosphocholine (SLPC), and 1,3-distearoyl-2-linoleoyl-glycerol (SLS), while ketones, especially saturated methyl ketones, were the major VOCs of 1,3-distearoyl-2-oleoyl-glycerol (SOS). The monitoring of the oxidative degradation using liquid chromatography–electrospray ionization–mass spectrometry (LC–ESI–MS) showed that either monounsaturated or diunsaturated fatty acyl groups were less oxidized when in the form of PCs than when in the form of TAGs. This finding demonstrated that the choline group in the form of PCs could increase the stability of fatty acyl groups to oxidation in comparison to TAGs
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