221 research outputs found

    Protein Thiol Modification and Thiol Proteomics

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    Investigating the Behavior of Adsorbed CO2 in Metal-Organic Frameworks via 13C Solid-state NMR Spectroscopy

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    Metal-organic frameworks (MOFs) are a class of microporous materials with lots of unique properties that make them promising candidates for carbon dioxide (CO2) capture and storage. In this thesis, the adsorption behavior of CO2 in MOF UTSA-74 (a framework isomer of a well-known MOF, MOF-74-Zn) is studied at a molecular level as it is a promising material for CO2 storage. It has a distinct binuclear secondary building unit (SBU) that one of metal ions (Zn1) is in a tetrahedral coordination with no binding sites, while the other one (Zn2) is in an octahedral geometry with two open metal sites (OMSs) upon activation. Explicitly, variable temperature (VT) 13C static solid-state nuclear magnetic resonance spectroscopy is used to investigate the behavior of 13CO2 in UTSA-74 at low, moderate and high loading levels of 13CO2 (i.e. 0.30, 0.54, 0.90 and 1.48 13CO2/ Zn2). The results reveal that all 13CO2 molecules undergo localized wobbling. At low loading, some 13CO2 molecules jump among three Zn2 OMSs in the cross-section of the channel, while others hop back and forth between the two neighbouring OMSs. At high loading, the three-site jumping has ceased, but two-site hopping persists. The dynamical behavior of 13CO2 in UTSA-74 results from the unique Zn2 coordination environment. It was also discovered that 13CO2 is less mobile in UTSA-74 than in its framework isomer, MOF-74-Zn

    Generalized-Equiangular Geometry CT: Concept and Shift-Invariant FBP Algorithms

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    With advanced X-ray source and detector technologies being continuously developed, non-traditional CT geometries have been widely explored. Generalized-Equiangular Geometry CT (GEGCT) architecture, in which an X-ray source might be positioned radially far away from the focus of arced detector array that is equiangularly spaced, is of importance in many novel CT systems and designs. GEGCT, unfortunately, has no theoretically exact and shift-invariant analytical image reconstruction algorithm in general. In this study, to obtain fast and accurate reconstruction from GEGCT and to promote its system design and optimization, an in-depth investigation on a group of approximate Filtered BackProjection (FBP) algorithms with a variety of weighting strategies has been conducted. The architecture of GEGCT is first presented and characterized by using a normalized-radial-offset distance (NROD). Next, shift-invariant weighted FBP-type algorithms are derived in a unified framework, with pre-filtering, filtering, and post-filtering weights. Three viable weighting strategies are then presented including a classic one developed by Besson in the literature and two new ones generated from a curvature fitting and from an empirical formula, where all of the three weights can be expressed as certain functions of NROD. After that, an analysis of reconstruction accuracy is conducted with a wide range of NROD. We further stretch the weighted FBP-type algorithms to GEGCT with dynamic NROD. Finally, the weighted FBP algorithm for GEGCT is extended to a three-dimensional form in the case of cone-beam scan with a cylindrical detector array.Comment: 31 pages, 13 figure

    Decreased Glomerular Filtration Rate Is Associated with Mortality and Cardiovascular Events in Patients with Hypertension: A Prospective Study

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    BACKGROUND: Few studies reported the associations between decreased glomerular filtration rate (GFR) and mortality, coronary heart disease (CHD), and stroke in hypertensive patients. We aim to assess the associations between GFR and mortality, CHD, and stroke in hypertensive patients and to evaluate whether low GFR can improve the prediction of these outcomes in addition to conventional cardiovascular risk factors. METHODS AND FINDINGS: This is an observational prospective study and 3,711 eligible hypertensive patients aged ≥5 years from rural areas of China were used for the present analysis. The associations between eGFR and outcomes, followed by a median of 4.9 years, were evaluated using Cox proportional hazards models adjusting for other potential confounders. Low eGFR was independently associated with risk of all-cause mortality, cardiovascular mortality, and incident stroke [multivariable adjusted hazard ratios (95% confidence intervals) for eGFR <60 ml/min/1.73 m(2) relative to eGFR ≥90 ml/min/1.73 m(2) were 1.824 (1.047-3.365), 2.371 (1.109-5.068), and 2.493 (1.193-5.212), respectively]. We found no independent association between eGFR and the risk of CHD. For 4-year all-cause and cardiovascular mortality, integrated discrimination improvement (IDI) was positive when eGFR were added to traditional risk factors (1.51%, P = 0.016, and 1.99%, P = 0.017, respectively). For stroke and CHD events, net reclassification improvements (NRI) were 5.9% (P = 0.012) and 1.8% (P = 0.083) for eGFR, respectively. CONCLUSIONS: We have established an inversely independent association between eGFR and all-cause mortality, cardiovascular mortality, and stroke in hypertensive patients in rural areas of China. Further, addition of eGFR significantly improved the prediction of 4-year mortality and stroke over and above that of conventional risk factors. We recommend that eGFR be incorporated into prognostic assessment for patients with hypertension in rural areas of China. LIMITATIONS: We did not have sufficient information on atrial fibrillation to control for the potential covariate. These associations should be further confirmed in future

    A novel criterion of metabolically healthy obesity could effectively identify individuals with low cardiovascular risk among Chinese cohort

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    Background and objectiveObesity has become a serious public health problem and brings a heavy burden of cardiovascular disease. Metabolically healthy obesity (MHO) is defined as individuals with obesity with no or only minor metabolic complications. Whether individuals with MHO have a lower cardiovascular risk remains controversial. In this study, a new criterion was used to define MHO and assess its predictive value for cardiovascular events and death. At the same time, the new criterion and the traditional criterion are compared to analyze the differences between different diagnostic criteria.MethodsA prospective cohort was established in northeast rural China from 2012 to 2013. Follow-up was conducted in 2015 and 2018 to investigate the incidence of cardiovascular events and survival. Subjects were grouped according to the metabolic health and obesity status. Kaplan-Meier curves were drawn to describe the cumulative risk of endpoint events in the four groups. Cox regression analysis model was constructed to evaluate the risk of endpoint events. Analysis of variance and post hoc analyses were used to calculate and compare differences in metabolic markers between MHO subjects diagnosed by novel and traditional criteria.ResultsA total of 9345 participants 35 years of age or older without a history of cardiovascular disease were included in this study. After a median follow-up of 4.66 years, the data showed that participants in the MHO group had no significant increase in the risk of composite cardiovascular events and stroke, but had a 162% increase in the risk of coronary heart disease (HR: 2.62; 95%CI: 1.21-5.67). However, when using conventional criteria for metabolic health, mMHO group had a 52% increase in combined CVD risk (HR: 1.52; 95%CI: 1.14-2.03). By comparing the differences of metabolic indicators between MHO subjects diagnosed by the two criteria, MHO subjects diagnosed by the new criterion had higher WC, WHR, TG, FPG, and lower HDL-C levels except for lower blood pressure, showing more exposure to cardiovascular risk factors.ConclusionsThe risk of combined CVD and stroke was not increased in MHO subjects. The new metabolic health criterion is superior to the traditional criterion and can effectively identify individuals with obesity with a lower risk of combined CVD. Blood pressure levels may be responsible for the inconsistent risk of combined CVD in MHO subjects diagnosed with both criteria