32 research outputs found

    Stereospecific Dehydroxytrifluoromethylthiolation of Alcohols Promoted by a Combination of Hypervalent Trifluoromethylthio-iodine(III) Reagent and N‑Heterocyclic Carbene

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    Direct dehydroxytrifluoromethylthiolation of alcohols is an attractive strategy for accessing CF3S-containing compounds. Herein, we report a method for dehydroxytrifluoromethylthiolation of alcohols by using the combination of hypervalent iodine(III) reagent TFTI and N-heterocyclic carbenes. This method shows excellent stereospecificity and chemoselectivity to give a product with clean inversion of the configuration of hydroxyl groups as well as can be used for late-stage modification of structurally complex alcohols. The reaction mechanism is proposed with experimental and computational evidence

    Unusual 2D → 3D Polycatenane Frameworks Based on 1D → 2D Interdigitated Layers: From Single Crystals to Submicrometer Fibers with Enhanced UV Photocatalytic Degradation Performances

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    Four unusual isomorphous metal–organic frameworks, [M<sub>2</sub>(L1)­(L2)<sub>2</sub>] (M = Co for <b>1</b>, Mn for <b>2</b>, Zn for <b>3</b>, and Cd for <b>4</b>), where H<sub>4</sub>L1 = tetrakis­[4-(carboxyphenyl)-oxamethyl]­methane acid and L2 = 4-tolyl-2,2′:6′,2″-terpyridine, have been synthesized under hydrothermal conditions. Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by infrared spectra, elemental analyses, powder X-ray diffraction, UV–vis absorption spectra, and optical energy gaps. In compounds <b>1</b>–<b>4</b>, the metal atoms are linked by the L1 anions to yield a chain with a loop. Every loop of each chain is penetrated by two L2 ligand rods belonging to the two nearest chains, resulting in an unusual 1D → 2D interdigitated network. In the 2D interdigitated network, there exist weak π–π interactions between pyridyl groups of L2 ligands. If the π–π interactions are regarded as linkers, the 2D interdigitated network belongs to an uneven (3,4)-connected layer. Furthermore, each individual (3,4)-connected layer is polycatenated with an infinite number of other perpendicular layers, yielding an unusual 2D → 3D polycatenane framework. The luminescent properties of compounds <b>3</b> and <b>4</b> have been studied. In addition, compounds <b>1</b>–<b>4</b> exhibit photocatalytic activities for MB degradation under UV irradiation. Submicrometer fiber <b>1′</b> shows high photocatalytic efficiency for MB degradation with respect to its corresponding macroscaled crystalline <b>1</b>

    Subgroup analysis of the relationship between age and lymph node involvement by tumor size.

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    <p>Subgroup analysis of the relationship between age and lymph node involvement by tumor size.</p

    Univariante and multivariate logistic regression for lymph node involvement in the first and the second dataset.

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    <p>Univariante and multivariate logistic regression for lymph node involvement in the first and the second dataset.</p

    Tumor characteristics and lymph node involvement according to age in the two datasets.

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    <p>*Data of tumor grade are available in 66.6% subjects in the first dataset and 92.5% in the second dataset.</p><p>&Immunohistochemical data on ER/PR/HER2 status in the dataset of 2008 is currently being checked and replenished. Only half of values (n = 997, 45.9%) are available. Therefore, the analysis of variable “breast cancer subtype” is not performed in the second dataset.</p

    Patient selection and patient subsets analyzed.

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    <p># 5 variables denote lymph node, age, pathology, tumor size, and subtype * 4 variables denote lymph node, age, pathology, and tumor size.</p

    Multigram-Scale Synthesis of High-Pt-Content PtCo Intermetallic Catalysts for Proton Exchange Membrane Fuel Cells

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    Carbon-supported PtCo intermetallic nanoparticles rank as one of the most efficient cathode catalysts for proton exchange membrane fuel cells (PEMFCs). Nevertheless, developing simple and scalable synthetic approaches for effective size control of this type of catalyst at high Pt contents continues to be a significant challenge. Herein, we introduce a sulfur-containing molecule-assisted ball-milling method, enabling the multigram-scale synthesis of PtCo intermetallic catalysts with a high Pt content of 48 wt %. This method results in a fine dispersion of PtCo intermetallic nanoparticles on carbon black supports with an average particle size of 5.29 nm. The resulting catalyst demonstrates remarkable performance in H2-Air PEMFC tests, exemplified by a power density of 1.16 W/cm2 at 0.7 V and maintaining 65% of its mass activity after an accelerated durability test

    Relation between age and lymph node involvement based on univariate nonparametric smoothing method.

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    <p>(A) The first dataset using univariate nonparametric smoothing method (n = 3,715) (B) The second dataset using univariate nonparametric smoothing method (n = 1,832) (C) The combined two datasets using univariate nonparametric smoothing method (n = 5,547).</p

    Abnormal Chloride Homeostasis in the Substancia Nigra Pars Reticulata Contributes to Locomotor Deficiency in a Model of Acute Liver Injury

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    <div><p>Background</p><p>Altered chloride homeostasis has been thought to be a risk factor for several brain disorders, while less attention has been paid to its role in liver disease. We aimed to analyze the involvement and possible mechanisms of altered chloride homeostasis of GABAergic neurons within the substantia nigra pars reticulata (SNr) in the motor deficit observed in a model of encephalopathy caused by acute liver failure, by using glutamic acid decarboxylase 67 - green fluorescent protein knock-in transgenic mice.</p><p>Methods</p><p>Alterations in intracellular chloride concentration in GABAergic neurons within the SNr and changes in the expression of two dominant chloride homeostasis-regulating genes, KCC2 and NKCC1, were evaluated in mice with hypolocomotion due to hepatic encephalopathy (HE). The effects of pharmacological blockade and/or activation of KCC2 and NKCC1 functions with their specific inhibitors and/or activators on the motor activity were assessed.</p><p>Results</p><p>In our mouse model of acute liver injury, chloride imaging indicated an increase in local intracellular chloride concentration in SNr GABAergic neurons. In addition, the mRNA and protein levels of KCC2 were reduced, particularly on neuronal cell membranes; in contrast, NKCC1 expression remained unaffected. Furthermore, blockage of KCC2 reduced motor activity in the normal mice and led to a further deteriorated hypolocomotion in HE mice. Blockade of NKCC1 was not able to normalize motor activity in mice with liver failure.</p><p>Conclusion</p><p>Our data suggest that altered chloride homeostasis is likely involved in the pathophysiology of hypolocomotion following HE. Drugs aimed at restoring normal chloride homeostasis would be a potential treatment for hepatic failure.</p></div

    Reduced level of KCC2 protein and unaltered level of NKCC1 protein in the SNr by TAA injection.

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    <p>Western blot experiments were performed for analysis of KCC2 (A and B) and NKCC1 (C and D) proteins in the SNr of TAA-injected and sham mice at different time points. All data have been normalized to actin levels within the same sample. Data are calculated as percentages of the average value of control mice (B and D). Note that a dramatic down-regulation of KCC2 protein was seen at 1 d and 2 d in the TAA group (B). No significant change of NKCC1 protein was seen at different time points in TAA group compared with those in sham group (D). * <i>P</i><0.05 vs sham controls.</p