433 research outputs found

    Atomic-scale combination of germanium-zinc nanofibers for structural and electrochemical evolution

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    Alloys are recently receiving considerable attention in the community of rechargeable batteries as possible alternatives to carbonaceous negative electrodes; however, challenges remain for the practical utilization of these materials. Herein, we report the synthesis of germanium-zinc alloy nanofibers through electrospinning and a subsequent calcination step. Evidenced by in situ transmission electron microscopy and electrochemical impedance spectroscopy characterizations, this one-dimensional design possesses unique structures. Both germanium and zinc atoms are homogenously distributed allowing for outstanding electronic conductivity and high available capacity for lithium storage. The as-prepared materials present high rate capability (capacity of similar to 50% at 20 C compared to that at 0.2 C-rate) and cycle retention (73% at 3.0 C-rate) with a retaining capacity of 546 mAh g(-1) even after 1000 cycles. When assembled in a full cell, high energy density can be maintained during 400 cycles, which indicates that the current material has the potential to be used in a large-scale energy storage system

    Italian Association of Sleep Medicine (AIMS) position statement and guideline on the treatment of menopausal sleep disorders

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    Insomnia, vasomotor symptoms (VMS) and depression often co-occur after the menopause, with consequent health problems and reductions in quality of life. The aim of this position statement is to provide evidence-based advice on the management of postmenopausal sleep disorders derived from a systematic review of the literature. The latter yielded results on VMS, insomnia, circadian rhythm disorders, obstructive sleep apnea (OSA) and restless leg syndrome (RLS). Overall, the studies show that menopausal hormone therapy (MHT) improves VMS, insomnia, and mood. Several antidepressants can improve insomnia, either on their own or in association with MHT; these include selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), and mirtazapine. Long-term benefits for postmenopausal insomnia may also be achieved with non-drug strategies such as cognitive behavioral therapy (CBT) and aerobic exercise. Continuous positive airway pressure (CPAP) and mandibular advancement devices (MADs) both reduce blood pressure and cortisol levels in postmenopausal women suffering from OSA. However, the data regarding MHT on postmenopausal restless legs syndrome are conflicting

    Pseudo-single crystal electrochemistry on polycrystalline electrodes : visualizing activity at grains and grain boundaries on platinum for the Fe2+/Fe3+ redox reaction

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    The influence of electrode surface structure on electrochemical reaction rates and mechanisms is a major theme in electrochemical research, especially as electrodes with inherent structural heterogeneities are used ubiquitously. Yet, probing local electrochemistry and surface structure at complex surfaces is challenging. In this paper, high spatial resolution scanning electrochemical cell microscopy (SECCM) complemented with electron backscatter diffraction (EBSD) is demonstrated as a means of performing ‘pseudo-single-crystal’ electrochemical measurements at individual grains of a polycrystalline platinum electrode, while also allowing grain boundaries to be probed. Using the Fe2+/3+ couple as an illustrative case, a strong correlation is found between local surface structure and electrochemical activity. Variations in electrochemical activity for individual high index grains, visualized in a weakly adsorbing perchlorate medium, show that there is higher activity on grains with a significant (101) orientation contribution, compared to those with (001) and (111) contribution, consistent with findings on single-crystal electrodes. Interestingly, for Fe2+ oxidation in a sulfate medium a different pattern of activity emerges. Here, SECCM reveals only minor variations in activity between individual grains, again consistent with single-crystal studies, with a greatly enhanced activity at grain boundaries. This suggests that these sites may contribute significantly to the overall electrochemical behavior measured on the macroscale

    The development of highly potent and selective small molecule correctors of Z α1-antitrypsin misfolding

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    α1-antitrypsin deficiency is characterised by the misfolding and intracellular polymerisation of mutant α1-antitrypsin protein within the endoplasmic reticulum (ER) of hepatocytes. Small molecules that bind and stabilise Z α1-antitrypsin were identified via a DNA-encoded library screen. A subsequent structure based optimisation led to a series of highly potent, selective and cellular active α1-antitrypsin correctors

    Modern microwave methods in solid state inorganic materials chemistry: from fundamentals to manufacturing

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    Common variable immunodeficiency complicated with hemolytic uremic syndrome

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    Common variable immunodeficiency is a primary immunodeficiency disease characterized by reduced serum immunoglobulins and heterogeneous clinical features. Recurrent pyogenic infections of upper and lower respiratory tracts are the main clinical manifestations of common variable immunodeficiency. Hemolytic uremic syndrome is a multisystemic disorder characterized by thrombocytopenia, microangiopathic hemolytic anemia, and organ ischemia due to platelet aggregation in the arterial microvasculature. This is one of the rare cases of patients diagnosed with common variable immunodeficiency, which was complicated by hemolytic uremic syndrome

    Direct non-cyclooxygenase-2 targets of celecoxib and their potential relevance for cancer therapy

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    Celecoxib (Celebrex®) was developed as a selective cyclooxygenase-2 (COX-2) inhibitor for the treatment of chronic pain. However, it now appears that this compound harbours additional pharmacologic activities that are entirely independent of its COX-2-inhibitory activity. This review presents the recently emerged direct non-COX-2 targets of celecoxib and their proposed role in mediating this drug's antitumour effects

    The Compartmentalisation of Phosphorylated Free Oligosaccharides in Cells from a CDG Ig Patient Reveals a Novel ER-to-Cytosol Translocation Process

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    BACKGROUND: Biosynthesis of the dolichol linked oligosaccharide (DLO) required for protein N-glycosylation starts on the cytoplasmic face of the ER to give Man(5)GlcNAc(2)-PP-dolichol, which then flips into the ER for further glycosylation yielding mature DLO (Glc(3)Man(9)GlcNAc(2)-PP-dolichol). After transfer of Glc(3)Man(9)GlcNAc(2) onto protein, dolichol-PP is recycled to dolichol-P and reused for DLO biosynthesis. Because de novo dolichol synthesis is slow, dolichol recycling is rate limiting for protein glycosylation. Immature DLO intermediates may also be recycled by pyrophosphatase-mediated cleavage to yield dolichol-P and phosphorylated oligosaccharides (fOSGN2-P). Here, we examine fOSGN2-P generation in cells from patients with type I Congenital Disorders of Glycosylation (CDG I) in which defects in the dolichol cycle cause accumulation of immature DLO intermediates and protein hypoglycosylation. METHODS AND PRINCIPAL FINDINGS: In EBV-transformed lymphoblastoid cells from CDG I patients and normal subjects a correlation exists between the quantities of metabolically radiolabeled fOSGN2-P and truncated DLO intermediates only when these two classes of compounds possess 7 or less hexose residues. Larger fOSGN2-P were difficult to detect despite an abundance of more fully mannosylated and glucosylated DLO. When CDG Ig cells, which accumulate Man(7)GlcNAc(2)-PP-dolichol, are permeabilised so that vesicular transport and protein synthesis are abolished, the DLO pool required for Man(7)GlcNAc(2)-P generation could be depleted by adding exogenous glycosylation acceptor peptide. Under conditions where a glycotripeptide and neutral free oligosaccharides remain predominantly in the lumen of the ER, Man(7)GlcNAc(2)-P appears in the cytosol without detectable generation of ER luminal Man(7)GlcNAc(2)-P. CONCLUSIONS AND SIGNIFICANCE: The DLO pools required for N-glycosylation and fOSGN2-P generation are functionally linked and this substantiates the hypothesis that pyrophosphatase-mediated cleavage of DLO intermediates yields recyclable dolichol-P. The kinetics of cytosolic fOSGN2-P generation from a luminally-generated DLO intermediate demonstrate the presence of a previously undetected ER-to-cytosol translocation process for either fOSGN2-P or DLO

    Cancer chemoprevention: lessons learned and future directions

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    The concept of delaying or preventing epithelial transformation remains a viable and attainable goal for the future. Drug-based strategies for chemoprevention of the future may predominantly rely upon targeted therapies with tolerable but defined toxicities for treatment of individuals diagnosed with intraepithelial neoplasias. Foods, diet manipulation strategies, or nutraceuticals may be more appropriate to delay or prevent carcinogenesis progression in healthy populations with genetic or epidemiologic evidence of risk for future transformation
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