560 research outputs found

    Diacridinium trans-diaqua­bis(pyrazine-2,3-dicarboxyl­ato)cobaltate(II) hexa­hydrate

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    The title compound, (C13H10N)2[Co(C6H2N2O4)2(H2O)2]·6H2O, consists of mononuclear trans-[Co(pz-2,3-dc)2(H2O)2]2− complex anions, (acrH)+ cations and uncoordinated water mol­ecules (acr is acridine and pz-2,3-dcH2 is pyrazine-2,3-dicarboxylic acid). The CoII atom, which lies on a crystallographic center of symmetry, has a slightly distorted octa­hedral coordination environment, with two N and two O atoms from the (pz-2,3-dc)2− ligands in the equatorial plane and with two water mol­ecules in axial positions. In the crystal, the components are held together by two distinct N—H⋯O and C—H⋯O hydrogen bonds with R 2 2(8) graph-sets. The coordinated and uncoordinated water mol­ecules are also involved in O—H⋯O hydrogen bonds, which lead to the formation of layers with R 3 3(12) graph-set motifs. Extensive π–π stacking inter­actions between parallel aromatic rings of the acridinium ions, with distances ranging from 3.533 (1) to 3.613 (1) Å, occur in the structure

    Solubility and Charge Transport in Blends of Poly-dialkoxy-p-phenylene Vinylene and UV-Cross-Linkable Matrices

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    Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) is blended with two different inert UV-cross-linkable matrices to tune the solubility of the solution-processed films. It is found that only 10 wt% of theses matrices is required to make the blend layer insoluble after cross-linking. The addition of only 10 wt% matrix only slightly reduces the hole mobility, whereas the electron transport is not affected. Polymer light-emitting diodes (PLEDs) with an insoluble 90:10 MEH-PPV: matrix blend layer exhibit the same current density and photocurrent as pristine MEH-PPV PLEDs

    Quantitative and qualitative differences in subcutaneous adipose tissue stores across lipodystrophy types shown by magnetic resonance imaging

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    BACKGROUND: Lipodystrophies are characterized by redistributed subcutaneous fat stores. We previously quantified subcutaneous fat by magnetic resonance imaging (MRI) in the legs of two patients with familial partial lipodystrophy subtypes 2 and 3 (FPLD2 and FPLD3, respectively). We now extend the MRI analysis across the whole body of patients with different forms of lipodystrophy. METHODS: We studied five subcutaneous fat stores (supraclavicular, abdominal, gluteal, thigh and calf) and the abdominal visceral fat stores in 10, 2, 1, 1 and 2 female subjects with, respectively, FPLD2, FPLD3, HIV-related partial lipodystrophy (HIVPL), acquired partial lipodystrophy (APL), congenital generalized lipodystrophy (CGL) and in six normal control subjects. RESULTS: Compared with normal controls, FPLD2 subjects had significantly increased supraclavicular fat, with decreased abdominal, gluteal, thigh and calf subcutaneous fat. FPLD3 subjects had increased supraclavicular and abdominal subcutaneous fat, with less severe reductions in gluteal, thigh and calf fat compared to FPLD2 subjects. The repartitioning of fat in the HIVPL subject closely resembled that of FPLD3 subjects. APL and CGL subjects had reduced upper body, gluteal and thigh subcutaneous fat; the APL subject had increased, while CGL subjects had decreased subcutaneous calf fat. Visceral fat was markedly increased in FPLD2 and APL subjects. CONCLUSION: Semi-automated MRI-based adipose tissue quantification indicates differences between various lipodystrophy types in these studied clinical cases and is a potentially useful tool for extended quantitative phenomic analysis of genetic metabolic disorders. Further studies with a larger sample size are essential for confirming these preliminary findings

    Aphrodisiac activity of 50% ethanolic extracts of Myristica fragrans Houtt. (nutmeg) and Syzygium aromaticum (L) Merr. & Perry. (clove) in male mice: a comparative study

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    BACKGROUND: Spices are considered as sexual invigorators in the Unani System of Medicine. In order to explore the sexual function improving effect of Myristica fragrans Houtt. (nutmeg) and Syzygium aromaticum (L) Merr. & Perry. (clove) an experimental study was conducted in normal male mice. METHODS: The extracts (50% ethanolic) of nutmeg and clove were administered (500 mg/kg; p.o.) to different groups of male Swiss mice. Mounting behaviour, mating performance, and general short term toxicity of the test drugs were determined and compared with the standard drug Penegra (Sildenafil citrate). RESULTS: The extracts of the nutmeg and clove were found to stimulate the mounting behaviour of male mice, and also to significantly increase their mating performance. The drugs were devoid of any conspicuous general short term toxicity. CONCLUSION: The extracts (50% ethanolic) of nutmeg and clove enhanced the sexual behaviour of male mice

    Room temperature triplet state spectroscopy of organic semiconductors

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    Organic light-emitting devices and solar cells are devices that create, manipulate, and convert excited states in organic semiconductors. It is crucial to characterize these excited states, or excitons, to optimize device performance in applications like displays and solar energy harvesting. This is complicated if the excited state is a triplet because the electronic transition is ‘dark’ with a vanishing oscillator strength. As a consequence, triplet state spectroscopy must usually be performed at cryogenic temperatures to reduce competition from non-radiative rates. Here, we control non-radiative rates by engineering a solid-state host matrix containing the target molecule, allowing the observation of phosphorescence at room temperature and alleviating constraints of cryogenic experiments. We test these techniques on a wide range of materials with functionalities spanning multi-exciton generation (singlet exciton fission), organic light emitting device host materials, and thermally activated delayed fluorescence type emitters. Control of non-radiative modes in the matrix surrounding a target molecule may also have broader applications in light-emitting and photovoltaic devices.United States. Dept. of Energy. Center for Excitonics (Award DE-SC0001088

    Suppressing molecular motions for enhanced room-temperature phosphorescence of metal-free organic materials

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    Metal-free organic phosphorescent materials are attractive alternatives to the predominantly used organometallic phosphors but are generally dimmer and are relatively rare, as, without heavy-metal atoms, spin-orbit coupling is less efficient and phosphorescence usually cannot compete with radiationless relaxation processes. Here we present a general design rule and a method to effectively reduce radiationless transitions and hence greatly enhance phosphorescence efficiency of metal-free organic materials in a variety of amorphous polymer matrices, based on the restriction of molecular motions in the proximity of embedded phosphors. Covalent cross-linking between phosphors and polymer matrices via Diels-Alder click chemistry is devised as a method. A sharp increase in phosphorescence quantum efficiency is observed in a variety of polymer matrices with this method, which is ca. two to five times higher than that of phosphor-doped polymer systems having no such covalent linkage.ope
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