4,392 research outputs found
Incorporation of aged dissolved organic carbon (DOC) by oceanic particulate organic carbon (POC): An experimental approach using natural carbon isotopes
No full textIncorporation of 14 C-depleted (old) dissolved organic carbon (DOC) on/into particulate organic carbon (POC) has been suggested as a possible mechanism to explain the low Delta C-14-POC values observed in the deep ocean [Druffel, E.R.M., Williams, P.M., 1990. Identification of a deep marine source of particulate organic carbon using bomb C-14. Nature, 347, 172-174.]. A shipboard incubation experiment was performed in the Sargasso Sea to test this hypothesis. Finely ground dried plankton was incubated in seawater samples from the deep Sargasso Sea, both with and without a biological poison (HgCl2). Changes ill parameters such as biochemical composition and carbon isotopic signatures of bulk POC and its organic compound classes were examined to study the roles of sorptive processes and biotic activity on POC character. Following a 13-day incubation, the relative abundance of the acid-insoluble organic fraction increased. Abundances of extractable lipids and total hydrolyzable amino acids decreased for both treatments, but by a greater extent in the non-poisoned treatment. The Delta C-14 values of POC recovered from the non-poisoned treatment were significantly lower than the value of the unaltered plankton material used for the incubation, indicating incorporation of C-14-depleted carbon, most likely DOC. The old carbon was present only in the lipid and acid-insoluble fractions. These results are consistent with previous findings of old carbon dominating the same organic fractions of sinking POC from the deep Northeast Pacific [Hwang, J., Druffel, E.R.M., 2003. Lipid-like material as the Source of the uncharacterized organic carbon in the ocean? Science, 299, 881-884.]. However, the Delta C-14 values of POC recovered from the poisoned treatment did not change as much as those from the non-poisoned treatment suggesting that biological processes were involved in the incorporation of DOC on/into POC. (c) 2005 Elsevier B.V. All rights reserved.X1122sciescopu
Lipid-like material as the source of the uncharacterized organic carbon in the ocean?
No full textThe composition and formation mechanisms of the uncharacterized fraction of oceanic particulate organic carbon (POC) are not well understood. We isolated biologically important compound classes and the acid-insoluble fraction, a proxy of the uncharacterized fraction, from sinking POC in the deep Northeast Pacific and measured carbon isotope ratios to constrain the source(s) of the uncharacterized fraction. Stable carbon and radiocarbon isotope signatures of the acid-insoluble fraction were similar to those of the lipid fraction, implying that the acid-insoluble fraction might be composed of selectively accumulated lipid-like macromolecules.X1155sciescopu
Impact of Type 2 Diabetes Mellitus and Antidiabetic Medications on Bone Metabolism
No full textPURPOSE OF REVIEW: This review focuses on the complex interactions between hyperglycemia and bone fragility and the effects of antidiabetic medications on bone metabolism.
RECENT FINDINGS: Type 2 diabetes (T2D) is associated with increased risk of bone fracture even in those with increased or normal bone mineral density (BMD). The pathophysiology of diabetic bone disease is not completely understood, but it is thought to be multifactorial and associated with complex cross talk among factors such as AGEs, IGF-1, enteric hormones, and pro-inflammatory cytokines. Treatment for T2D may have an impact on bone metabolism. Diabetic bone disease should be considered a serious complication of long-standing T2D
Genetic aspects of type 1 diabetes
Full text linkType 1 diabetes mellitus (T1DM) is characterized by autoimmune destruction of pancreatic beta-cells in genetically predisposed individuals, eventually resulting in severe insulin deficiency. It is the most common form of diabetes in children and adolescents. Genetic susceptibility plays a crucial role in development of T1DM. The human leukocyte antigen complex plays a key role in the pathogenesis of T1DM. Furthermore, genome-wide association studies and linkage analysis have recently made a significant contribution to current knowledge relative to the impact of genetics on T1DM development and progression. This review focuses on current knowledge of genetics as a pathogenesis for T1DM. It also discusses mechanisms by which genes influence the risk of developing T1DM as well as the clinical and research applications of genetic risk scores in T1DM
Hybrid Organic-Inorganic Perovskite Memory with Long-Term Stability in Air
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Improved selectivity of oxide semiconductor type gas sensor using compensating element
No full textThe selectivity of SnO2 gas sensor for a hydrocarbon gas like i-C4H10 has been improved through the serial connection of a compensating element which is sensitive to the interfering gas. The devices were fabricated in 2 mm x 2 mm through the screen-printing technique. The sensing material, made of SnO2, was doped with Sb2O5 and treated with Pt catalyst to detect a hydrocarbon gas. The compensating material was composed of Sb2O5-doped SnO2 with Pd catalyst to detect interfering gas such as ethanol. The amount of resistance change in each material upon exposure to gas is differed depending on the kind of gas to be exposed, giving rise to an improvement in the selectivity of the device. (C) 2001 Elsevier Science B.V. All rights reserved.The authors wish to acknowledge the financial support of the Korean Research Foundation offered in the 1998 program year
A population-based study of TyG index distribution and its relationship to cardiometabolic risk factors in children and adolescents
Full text linkThe purpose of this study was to present age- and sex-specific distributions of the triglyceride-glucose (TyG) index and to evaluate their relationship with cardiometabolic risk factors in children and adolescents. A total of 7404 participants aged 10–18 years from the Korean National Health and Nutrition Survey were included as the reference population. The TyG index was calculated as ln(fasting triglyceride [mg/dL] × fasting glucose [mg/dL]/2). The percentile of the TyG index exhibited a steady linear relationship with age for both sexes. TyG index significantly correlated with waist circumference (WC) standard deviation score (SDS; r = 0.110, p < 0.001), systolic blood pressure (SBP; r = 0.104, p < 0.001), diastolic blood pressure (DBP; r = 0.083, p < 0.001), glucose (r = 0.220, p < 0.001), high-density lipoprotein cholesterol (HDL-C; r = − 0.325, p < 0.001), and triglycerides (TG; r = 0.926, p < 0.001). Multiple linear regression analysis revealed that the TyG index was significantly associated with WC SDS (β = 0.116, p < 0.001), SBP (β = 2.009, p < 0.001), DBP (β = 1.464, p < 0.001), glucose (β = 3.376, p < 0.001), HDL-C (β = − 6.431, p < 0.001), and TG (β = 85.518, p < 0.001). Our results suggest that the TyG index has a steady linear distribution for sex and age in children and adolescents and constitutes an indicator for predicting metabolic disorders that could lead to cardiovascular disease later in life
Fatigue life prediction of circular notched CFRP laminates
No full textFatigue life prediction and fatigue behavior of circular notched carbon fiber reinforced plastic laminates are presented. Point and average stress criteria proposed by Whitney and Nuismer are generalized to fatigue fracture criteria for notched laminates. Residual strength degradation model and the assumptions on the stress redistribution are introduced during the derivation of prediction equations. S-N curve, Basquin's relation, and Hwang and Han's fatigue life prediction equation (FLPE) 1 are chosen for evaluation of residual strength of unnotched laminates and six prediction equations are derived. Experiments are performed using carbon fiber reinforced plastic laminates. Presented prediction equations are reasonably close to experimental data and proposed approach is found to be suitable to predict fatigue life of notched composite laminates. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.X1111sciescopu
Effects of bonding temperature on the properties and reliabilities of anisotropic conductive films (ACFs) for flip chip on organic substrate application
No full textThe effects of bonding temperatures on the composite properties and reliability performances of anisotropic conductive films (ACFs) for flip chip on organic substrates assemblies were studied. As the bonding temperature decreased, the composite properties of ACF, such as water absorption, glass transition temperature (T-g), elastic modulus (E') and coefficient of thermal expansion (a), were improved. These results were due to the difference in network structures of cured ACFs which were fully cured at different temperatures. From small angle X-ray scattering (SAXS) test result, ACFs cured at lower temperature, had denser network structures. The reliability performances of flip chip on organic substrate assemblies using ACFs were also investigated as a function of bonding temperatures. The results in thermal cycling test (-55 degrees C/+1 50 degrees C, 1000 cycles) and PCT (121 degrees C, 100% RH, 96 h) showed that the lower bonding temperature resulted in better reliability of the flip chip interconnects using ACFs. Therefore, the composite properties of cured ACF and reliability of flip chip on organic substrate assemblies using ACFs were strongly affected by the bonding temperature. (C) 2007 Elsevier Ltd. All rights reserved
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