97 research outputs found

    A candidate LiBH4 for hydrogen storage: Crystal structures and reaction mechanisms of intermediate phases

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    First-principles calculation and x-ray diffraction simulation methods have been used to explore crystal structures and reaction mechanisms of the intermediate phases involved in dehydriding of LiBH4. LiBH4 was found to dehydride via two sequential steps: first dehydriding through LiBH, followed by the dehydriding of LiBH through LiB. The first step, which releases 13.1 wt. % hydrogen, was calculated to have an activation barrier of 2.33 eV per formula unit and was endothermic by 1.28 eV per formula unit, while the second step was endothermic by 0.23 eV per formula unit. On the other hand, if LiBH4 and LiBH each donated one electron, possibly to the catalyst doped on their surfaces, it was found that the barrier for the first step was reduced to 1.50 eV. This implies that the development of the catalyst to induce charge migration from the bulk to the surface is essential to make LiBH4 usable as a hydrogen storage material in a moderate temperature range, which is also important to stabilize the low-temperature structure of Pnma (no. 62) LiBH on dehydrogenation. Consequently, the high 13.1 wt. % hydrogen available from the dehydriding of LiBH4 and LiBH and their phase stability on Pnma when specific catalysts were used suggest that LiBH4 has good potential to be developed as the hydrogen storage medium capable of releasing the Department of Energy target of 6.5 wt. % for a hydrogen fuel cell car in a moderate temperature range

    Autoimmune Hypoglycemia in a Patient with Characterization of Insulin Receptor Autoantibodies

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    BackgroundType B insulin resistance syndrome is a manifestation of autoantibodies to the insulin receptor that results in severe hyperglycemia and acanthosis nigricans. However, the mechanisms by which these autoantibodies induce hypoglycemia are largely unknown. In this paper, we report the case of patient with type B insulin resistance syndrome who presented with frequent severe fasting hypoglycemia and acanthosis nigricans.MethodsTo evaluate the mechanism of hypoglycemia, we measured the inhibition of insulin binding to erythrocytes and IM9 lymphocytes in a sample of the patient's dialyzed serum before and after immunosuppressive therapy.ResultsIn the patient's pre-treatment serum IgG, the binding of 125I-insulin to erythrocytes was markedly inhibited in a dose-dependent manner until the cold insulin level reached 10-9 mol/L. We also observed dose-dependent inhibition of insulin binding to IM9 lymphocytes, which reached approximately 82% inhibition and persisted even when diluted 1:20. After treatment with glucocorticoids, insulin-erythrocyte binding activity returned to between 70% and 80% of normal, while the inhibition of insulin-lymphocyte binding was reduced by 17%.ConclusionWe treated a patient with type B insulin resistance syndrome showing recurrent fasting hypoglycemia with steroids and azathioprine. We characterized the patient's insulin receptor antibodies by measuring the inhibition of insulin binding

    Recurrent Renal Leiomyosarcoma Mimicking a Colonic Submucosal Tumor: A Case Report

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    A primary leiomyosarcoma of the kidney is a rare, but highly aggressive, neoplasm, accounting for only 0.1% of all invasive renal tumors. Local or systemic recurrence is common, but a leiomyosarcoma is difficult to diagnose preoperatively. We recently encountered an interesting case of an unusual recurrence of a renal leiomyosarcoma. A 57-year-old woman visited our hospital complaining of lower abdominal pain. Four years previously, she had undergone a left nephrectomy. She had a primary leiomyosarcoma of the kidney that had been misdiagnosed as a renal cell carcinoma. Colonoscopy revealed the presence of a lesion similar to a submucosal tumor in the descending colon. Postoperative pathologic examination confirmed that the mass was a recurrent leiomyosarcoma. We report this unusual case and present a review of the literature

    Resolution of Recalcitrant Uveitic Optic Disc Edema Following Administration of Methotrexate: Two Case Reports

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    A 13-year-old male and a 15-year-old female presented with optic disc edema associated with chronic recurrent uveitis. While the ocular inflammation responded to high doses of oral prednisolone, the disc edema showed little improvement. After oral administration of methotrexate, the disc edema and ocular inflammation were resolved, and the dose of oral corticosteroid could be reduced

    Silicon@porous nitrogen-doped carbon spheres through a bottom-up approach are highly robust lithium-ion battery anodes

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    Due to its excellent capacity, around 4000 mA h g(-1), silicon has been recognized as one of the most promising lithium-ion battery anodes, especially for future large-scale applications including electrical vehicles and utility power grids. Nevertheless, Si suffers from a short cycle life as well as limitations for scalable electrode fabrication. Herein, we report a novel design for highly robust and scalable Si anodes: Si nanoparticles embedded in porous nitrogen-doped carbon spheres (NCSs). The porous nature of NCSs buffers the volume changes of Si nanoparticles and thus resolves critical issues of Si anode operations, such as pulverization, vulnerable contacts between Si and carbon conductors, and an unstable solid-electrolyte interphase. The unique electrode structure exhibits outstanding performance with a gravimetric capacity as high as 1579 mA h g(-1) at a C/10 rate based on the mass of both Si and C, a cycle life of 300 cycles with 94% capacity retention, as well as a discharge rate capability of 6 min while retaining a capacity of 702 mA h g(-1). Significantly, the coulombic efficiencies of this structure reach 99.99%. The assembled structure suggests a design principle for high capacity alloying electrodes that suffer from volume changes during battery operations.

    Superior patient survival for continuous ambulatory peritoneal dialysis patients treated with a peritoneal dialysis fluid with neutral pH and low glucose degradation product concentration (Balance)

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    BACKGROUND: In recent years, laboratory and clinical research has suggested the need for peritoneal dialysis fluids (PDFs) that are more biocompatible than the conventional PDFs commonly used today. Bioincompatibility of PDF has been attributed to low pH, lactate, glucose, glucose degradation products (GDPs), and osmolality. PDFs with neutral pH and low GDPs are now available commercially. In vitro and early clinical studies suggest that these solutions are indeed more biocompatible but, as of now, there is no evidence that their use improves patient outcome. METHODS: Using a dedicated database of over 2000 patients treated with PD in Korea, we were able to conduct a retrospective observational study comparing outcomes for incident continuous ambulatory PD patients treated with a standard, conventional, heat-sterilized PDF to the outcomes for patients treated with a novel, low GDP, neutral-pH PDF prepared in a dual-compartment, double-bag PD system (Balance; Fresenius Medical Care, St. Wendel, Germany). In an intention-to-treat analysis, patient and technique survival, peritonitis-free survival, and peritonitis rates were compared in 611 patients treated with Balance for up to 30 months and 551 patients with a standard PDF (stay . safe; Fresenius Medical Care) treated in the same era and with equivalent follow-up. RESULTS: The patients were well matched for most relevant characteristics except older age distribution for the patients treated with the standard PDF. Patients treated with Balance had significantly superior survival compared to those treated with the standard PDF (74% vs 62% at 28 months, p = 0.0032). In a multivariate Cox regression model including age, diabetes, and gender, the survival advantage persisted (relative risk of death for Balance 0.75, 95% confidence interval 0.56 - 0.99, p = 0.0465). Modality technique survival was similarin Kaplan-Meieranalysis for both PDFs. No differences were detected in peritonitis-free survival or in peritonitis rates between the two solutions. CONCLUSION: This study, for the first time, suggests that treatment with a novel biocompatible PDF with low GDP concentration and neutral pH confers a significant survival advantage. The exact mechanisms for such a survival advantage cannot be determined from this study. The usual criticisms of observational studies apply and the results reported here strongly warrant the undertaking of appropriately designed, randomized, controlled clinical trials

    Regulation of Inhibitors of Differentiation Family Proteins by Thyroid-Stimulating Hormone in FRTL-5 Thyroid Cells

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    Members of the inhibitors of differentiation (Id) family of helix-loop-helix (HLH) proteins are known to play important roles in the proliferation and differentiation of many cell types. Thyroid-stimulating hormone (TSH) regulates proliferation and differentiation by activating TSH receptor (TSHR) in thyrocytes. In this study, we found that Id2, one of the Id family proteins, is a major target for regulation by TSH in FRTL-5 thyroid cells. TSH rapidly increases the Id2 mRNA level in FRTL-5 thyroid cells but the Id2 protein showed biphasic regulatory patterns, being transiently reduced and subsequently induced by TSH treatment. Transient reduction of Id2 protein was noted within 2 hr of TSH treatment and was mediated by proteasomal degradation. Moreover, reduced Id2 expression correlated with the activity of the phosphatidylinositol 3 kinase pathway, which is activated by TSH. Although TSH increases the activity of the Id2 promoter, TSH-induced activation of this promoter was independent of c-Myc. Id2 did not alter TTF-1- and Pax-8-mediated effects on the regulation of the Tg promoter. Thus, in summary, we found that TSH regulates Id2 expression, but that Id2 does not alter the expression of thyroid-specific genes, such as Tg, in FRTL-5 thyroid cells

    Isolation and characterization of canine umbilical cord blood-derived mesenchymal stem cells

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    Human umbilical cord blood-derived mesenchymal stem cells (MSCs) are known to possess the potential for multiple differentiations abilities in vitro and in vivo. In canine system, studying stem cell therapy is important, but so far, stem cells from canine were not identified and characterized. In this study, we successfully isolated and characterized MSCs from the canine umbilical cord and its fetal blood. Canine MSCs (cMSCs) were grown in medium containing low glucose DMEM with 20% FBS. The cMSCs have stem cells expression patterns which are concerned with MSCs surface markers by fluorescence-activated cell sorter analysis. The cMSCs had multipotent abilities. In the neuronal differentiation study, the cMSCs expressed the neuronal markers glial fibrillary acidic protein (GFAP), neuronal class III β tubulin (Tuj-1), neurofilament M (NF160) in the basal culture media. After neuronal differentiation, the cMSCs expressed the neuronal markers Nestin, GFAP, Tuj-1, microtubule-associated protein 2, NF160. In the osteogenic & chondrogenic differentiation studies, cMSCs were stained with alizarin red and toluidine blue staining, respectively. With osteogenic differentiation, the cMSCs presented osteoblastic differentiation genes by RT-PCR. This finding also suggests that cMSCs might have the ability to differentiate multipotentially. It was concluded that isolated MSCs from canine cord blood have multipotential differentiation abilities. Therefore, it is suggested that cMSCs may represent a be a good model system for stem cell biology and could be useful as a therapeutic modality for canine incurable or intractable diseases, including spinal cord injuries in future regenerative medicine studies
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