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Siderite records historical geological information about fluids, and thus can be used to trace diagenetic zones related to biogeochemical reactions. Siderite nodules have been found in Miocene marine shale in the Kuohsing area of Taiwan, but their genesis is not clear. Field observations show that the siderite is scattered in parallel discontinuous lenses in the shale, which consists mainly of authigenic siderite (78.63%) and other minerals. The REE distributions of the siderite are characterized by MREE enrichment with no Ce anomaly. This indicates that the siderite was formed in weakly oxidizing conditions, facilitating the precipitation of siderite in a suboxic zone. The <5I3C and <5l8O values of this siderite are from -3.69%e to +0.08%c and from -1.09%e to +0.25%c, respectively, suggesting that it was precipitated in the suboxic zone with an admixture of seawater and organic matter. Studies show that authigenic siderite can be used to identify biogeochemical processes in sediments and indicate diagenetic zones [ABSTRACT FROM AUTHOR]

Abstract: Extremely negative carbon isotope values from the Doushantuo cap dolostone succession in the Yangtze Gorges, South China were interpreted as direct evidence of the hypothesis of methane hydrate destabilization during the Marinoan deglaciation. However, this suggestion remains uncertain due to the obscurity of the paragenetic sequence of carbonate minerals with diverse carbon isotopic compositions. Here, we conducted macroscopic and microscopic petrographic and carbon isotopic investigations of the cap dolostone succession at the Jiulongwan section in the Yangtze Gorges. Our results show that extreme δ13C values down to −44‰ exclusively occur in calcite, whereas δ13C values for the host dolomite range mostly between −4‰ and −2‰, and clearly reveal that the host dolomite were locally dissolved and/or replaced by the calcite bearing highly 13C-depleted signals. This finding suggests that methane-oxidation activity as indicated by the strongly depleted δ13C signals did not occur until after the cap dolostone deposition. Thus, the presence of the extremely negative δ13C values could not be taken as evidence for the proposed methane hypothesis. Nevertheless, this conclusion is not contradictory to the scenario that massive releases of methane from permafrost hydrates during deglaciation, much prior to methane oxidation documented here, could drive substantial negative δ13C shifts well exhibited by the Doushantuo cap dolostone and others around the world. [Copyright &y& Elsevier]

Background and Objectives: To investigate the effects of oral preoperative regimens on gastric emptying time in relation to BMI in Chinese adults.Methods and Study Design: The enrolled 56 adults were divided into three groups (normal-weight, underweight, and overweight) and completed a regimen of two drinks after a 2-week interval. After drinking a carbohydrate regimen (CD, 50 g carbohydrates) or a carbohydrate glutamine regimen (CGD, 44 g carbohydrates and 6 g glutamine) labelled with 99mTc-DTPA (99mTc-diethylenetriaminepentaacetic acid), gastric emptying times T50 and T90 were measured using a curve derived from scintigraphic images.Results: T50 and T90 had no significant difference between the CD and CGD regimens. T50 was significantly delayed in the underweight participants (BMI <18.5 kg/m2, as Chronic Energy Deficiency, CED) compared with the normal-weight participants after drinking CD (p=0.003) or CGD (p=0.002), as well as T90 after CD (p=0.019). There was no difference in glucose concentrations between the three groups. There are negative correlations between body weight and gastric emptying time T50 (r=-0.461, p=0.016) or T90 (r=-0.553, p=0. 003) after drinking CD, as well as T50 (r=-0.553, p=0.003) after drinking CGD.Conclusions: Underweight adults should be careful to take oral preoperative regimens 2 hours before surgery and consider reducing the volume because of a slower gastric emptying rate. [ABSTRACT FROM AUTHOR]

Background/aims: This study investigated an association between obesity and impaired renal functions in elderly patients with nonalcoholic fatty liver disease (NAFLD) and evaluated the risk factors for chronic kidney disease (CKD) in these patients., Materials and Methods: A cross-sectional study was performed involving 515 elderly patients (≥ 60 years old) with NAFLD. Demographics, body mass index (BMI), medical history, and laboratory parameters were compared for groups stratified by obesity (≥ 28 kg/m2) or CKD. An association between obesity and CKD was analyzed, and a multivariate logistic regression analysis was conducted for risk factors associated with CKD., Results: In the overall population, 28.7% were obese and 54.8% had CKD; there were more women (58.8%) than men. The prevalence of hypertension and diabetes was similar between the obese and nonobese groups and between the CKD and non-CKD groups. Obese patients had significantly higher levels of serum uric acid and estimated glomerular filtration rates when compared with the nonobese group. When compared with those without CKD, patients with CKD were significantly older in addition to having higher BMI and serum uric acid levels. The multivariate logistic regression analysis indicated that CKD was positively associated with age, BMI, and serum uric acid levels., Conclusion: Elderly obese patients with NAFLD are at a higher risk of CKD. NAFLD patients with advanced age, greater BMI, or higher serum uric acid levels are more prone to developing CKD. The renal function of NAFLD patients should be closely monitored.