145 research outputs found

    Infrared Spectra and Density Functional Theoretical Calculation of Transition Metal Oxide Reaction with Monochloromethane

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    In this chapter, we presented a short review of past and present experimental and theoretical work on the reactions of the transition metal monoxide and dioxide molecules with monochloromethane in excess argon matrices. A series of infrared absorption spectra combining with density functional theoretical (DFT) calculation characterized that the transition metal monoxide molecules produced by laser-ablated higher oxides activated C─H and C─Cl bonds of CH3Cl to first form the weakly bound MO(CH3Cl) (M = Sc, Y, Nb, Ta, Ti, Zr, Mn, Fe) complexes, which further photoisomerized to the more stable chlorine-transfer (Cl-transfer) CH3OMCl (M = Sc, Y), CH3M(O)Cl (M = Ti, Zr), CH3MOCl (M = Mn, Fe), and agostic hydrogen-transfer (H-transfer) CH2ClMOH (M = Sc, Y, Nb, Ta) products upon limited light excitation. Transition metal dioxides reaction with CH3Cl also formed MO2(CH3Cl) (M = Ti, Zr, Nb, Ta) complexes, which were further rearranged to the more stable Cl-transfer CH3OM(O)Cl (M = Ti, Zr) and agostic H-transfer CH2ClM(O)OH (M = Nb, Ta) molecules between the metal center atom and the chlorine atom upon ultraviolet light irradiation. Their different reactivity was interpreted according to the different valence electrons of metal center

    Supercontinuum generation and carrier envelope offset frequency measurement in a tapered single-mode fiber

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    We report supercontinuum generation by launching femtosecond Yb fiber laser pulses into a tapered single-mode fiber of 3 um core diameter. A spectrum of more than one octave, from 550 to 1400 nm, has been obtained with an output power of 1.3 W at a repetition rate of 250 MHz, corresponding to a coupling efficiency of up to 60%. By using a typical f-2f interferometer, the carrier envelope offset frequency was measured and found to have a signal-to-noise ratio of nearly 30 dB.Comment: 10 pages, accepted by Appl Phys

    The impact of payer status on hospital admissions: evidence from an academic medical center

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    BACKGROUND: There are plenty of studies investigating the disparity of payer status in accessing to care. However, most studies are either disease-specific or cohort-specific. Quantifying the disparity from the level of facility through a large controlled study are rare. This study aims to examine how the payer status affects patient hospitalization from the perspective of a facility. METHODS: We extracted all patients with visiting record in a medical center between 5/1/2009-4/30/2014, and then linked the outpatient and inpatient records three year before target admission time to patients. We conduct a retrospective observational study using a conditional logistic regression methodology. To control the illness of patients with different diseases in training the model, we construct a three-dimension variable with data stratification technology. The model is validated on a dataset distinct from the one used for training. RESULTS: Patients covered by private insurance or uninsured are less likely to be hospitalized than patients insured by government. For uninsured patients, inequity in access to hospitalization is observed. The value of standardized coefficients indicates that government-sponsored insurance has the greatest impact on improving patients' hospitalization. CONCLUSION: Attention is needed on improving the access to care for uninsured patients. Also, basic preventive care services should be enhanced, especially for people insured by government. The findings can serve as a baseline from which to measure the anticipated effect of measures to reduce disparity of payer status in hospitalization.72033003 - National Natural Science Foundation of China; 71720107003 - National Natural Science Foundation of China; DMS-1664644 - National Science Foundation; IIS-1914792 - National Science Foundation; CNS-1645681 - National Science Foundation; R01 GM135930 - NIGMS NIH HHS; N00014-19-1-2571 - Office of Naval Research; R01-GM135930 - NIH HHSPublished versio

    Low Serum Vitamin D Is Associated with Anti-Thyroid-Globulin Antibody in Female Individuals

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    Objectives. Some evidence has pointed out that vitamin D plays a significant role in reducing the incidence of autoimmune diseases, especially autoimmune thyroid diseases. The authors aimed to examine the relationship between circulating 25-hydroxyvitamin D and thyroid autoantibody in a population-based health survey of Xinjiang Chinese population. Subjects and Methods. A total of 1714 Chinese adults were analyzed. 25(OH)D, anti-thyroid antibodies, and thyroid function were measured. Results. The prevalence of vitamin D insufficiency was 28.3% in Hans and 9.3% in Uyghurs, and the prevalence of vitamin D deficiency was 61.6% in Hans and 87.6% in Uyghurs. Overall prevalence of TgAb positivity was 6.2% (0.9% males; 5.3% females). In female subjects, mean serum 25(OH)D levels were significantly lower in Hans and Uyghurs compared with males, and the difference was statistically significant. Importantly, after adjusting for age and ethnicity, a negative correlation (r=-0.121, P=0.014) was recognized between 25(OH)D and TgAb levels only in female subjects. Conclusion. Vitamin D insufficiency and deficiency are prevalent among Chinese adults. Low serum 25(OH)D is related to the presence of TgAb in females. The causal effect of low vitamin D level on thyroid autoimmunity should be studied further more

    Thermo-Responsive Molecularly Imprinted Hydrogels for Selective Adsorption and Controlled Release of Phenol From Aqueous Solution

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    In this study, thermo-responsive molecularly imprinted hydrogels (T-MIHs) were developed as an effective potential adsorbent for selectively adsorption phenol from wastewater. During the process, N-isopropyl acrylamide (NIPAm) was used as thermal responsive monomer. The obtained materials were characterized in detail by fourier transform infrared (FT-IR) spectrometer, scanning electron microscope (SEM), and thermo gravimetric analysis (TGA). A series of static adsorption studies were performed to investigate the kinetics, specific adsorption equilibrium, and selective recognition ability of phenol. Reversible adsorption and release of phenol were realized by changing temperatures. Three type of phenols, namely 3-chlorophenols (3-CP), 2,4-dichlorophenol (2,4-DCP), and 2,4,6-trichlorophenol (2,4,6-TCP) were selected as model analytes to evaluate the selective recognition performance of T-MIHs. The T-MIHs have good selectivity, temperature response, and reusability, making them ideal in applying in the controlled separation and release of phenol pollutants

    Survivin gene silencing sensitizes prostate cancer cells to selenium growth inhibition

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    <p>Abstract</p> <p>Background</p> <p>Prostate cancer is a leading cause of cancer-related death in men worldwide. Survivin is a member of the inhibitor of apoptosis (IAP) protein family that is expressed in the majority of human tumors including prostate cancer, but is barely detectable in terminally differentiated normal cells. Downregulation of survivin could sensitize prostate cancer cells to chemotherapeutic agents <it>in vitro </it>and <it>in vivo</it>. Selenium is an essential trace element. Several studies have shown that selenium compounds inhibit the growth of prostate cancer cells. The objective of this study is to investigate whether survivin gene silencing in conjunction with selenium treatment could enhance the therapeutic efficacy for prostate cancer and to elucidate the underlying mechanisms.</p> <p>Methods</p> <p>Expression of survivin was analyzed in a collection of normal and malignant prostatic tissues by immunohistochemical staining. <it>In vitro </it>studies were conducted in PC-3M, C4-2B, and 22Rv1 prostate cancer cells. The effect of selenium on survivin expression was analyzed by Western blotting and semi-quantitative RT-PCR. Survivin gene knockdown was carried out by transfecting cells with a short hairpin RNA (shRNA) designed against survivin. Cell proliferation was quantitated by the 3-(4,5-Dimethylthiazol-2-yl)- 2,5-Diphenyltetrazolium Bromide (MTT) assay and apoptosis by propidium iodide staining followed by flow cytometry analysis. Finally, <it>in vivo </it>tumor growth assay was performed by establishing PC-3M xenograft in nude mice and monitoring tumor growth following transfection and treatment.</p> <p>Results</p> <p>We found that survivin was undetectable in normal prostatic tissues but was highly expressed in prostate cancers. Survivin knockdown or selenium treatment inhibited the growth of prostate cancer cells, but the selenium effect was modest. In contrast to what have been observed in other cell lines, selenium treatment had little or no effect on survivin expression in several androgen-independent prostate cancer cell lines. Survivin knockdown sensitized these cells to selenium growth inhibition and apoptosis induction. In nude mice bearing PC-3M xenografts, survivin knockdown synergizes with selenium in inhibiting tumor growth.</p> <p>Conclusions</p> <p>Selenium could inhibit the growth of hormone-refractory prostate cancer cells both <it>in vitro </it>and <it>in vivo</it>, but the effects were modest. The growth inhibition was not mediated by downregulating survivin expression. Survivin silencing greatly enhanced the growth inhibitory effects of selenium.</p

    Efficacy and safety of low-dose IL-2 in the treatment of systemic lupus erythematosus: A randomised, double-blind, placebo-controlled trial

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    Objectives Open-labelled clinical trials suggested that low-dose IL-2 might be effective in treatment of systemic lupus erythematosus (SLE). A double-blind and placebocontrolled trial is required to formally evaluate the safety and efficacy of low-dose IL-2 therapy. Methods A randomised, double-blind and placebocontrolled clinical trial was designed to treat 60 patients with active SLE. These patients received either IL-2 (n=30) or placebo (n=30) with standard treatment for 12 weeks, and were followed up for additional 12 weeks. IL-2 at a dose of 1 million IU or placebo was administered subcutaneously every other day for 2 weeks and followed by a 2-week break as one treatment cycle. The primary endpoint was the SLE Responder Index-4 (SRI-4) at week 12. The secondary endpoints were other clinical responses, safety and dynamics of immune cell subsets. Results At week 12, the SRI-4 response rates were 55.17% and 30.00% for IL-2 and placebo, respectively (p=0.052). At week 24, the SRI-4 response rate of IL-2 group was 65.52%, compared with 36.67% of the placebo group (p=0.027). The primary endpoint was not met at week 12. Low-dose IL-2 treatment resulted in 53.85% (7/13) complete remission in patients with lupus nephritis, compared with 16.67% (2/12) in the placebo group (p=0.036). No serious infection was observed in the IL-2 group, but two in placebo group. Besides expansion of regulatory T cells, low-dose IL-2 may also sustain cellular immunity with enhanced natural killer cells. Conclusions Low-dose IL-2 might be effective and tolerated in treatment of SThe work was supported by the National Natural Science Foundation of China (31530020,31570880,81471601,81601417 and 81701598), Peking-Tsinghua Center for Life Sciences to ZG LI, Beijing Sci-Tech Committee Z171100000417007,Clinical Medicine Plus X-Young Scholars Project of Peking University (PKU2019LCXQ013) supported by the Fundamental Research Funds for the Central Universities, Beijing Nova Program Z171100001117025, National Key Research and Development Program of China (2017YFC0909003 to DY), BellberryViertel Senior Medical Research Fellowship to DY and Beijing SL PHARM
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