5,243 research outputs found

    An investigation of the beneficial effects of adding carbon nanotubes to standard injection grout

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    Mortar grouting is often used in masonry constructions to mitigate structural decay and repair damage by filling cracks and voids, resulting in an improvement in mechanical properties. This paper presents an original experimental investigation on grout with added carbon nanotubes (CNTs). The samples were prepared with different percentages of CNTs, up to 1.2 wt% with respect to the binder, and underwent three‐point bending tests in crack mouth opening displacement mode and compressive tests. The results showed that very small additions (up to 0.12 wt% of CNTs) increased not only flexural and compressive strengths (+73% and 35%, respectively, in comparison with plain mortar) but also fracture energy (+80%). These results can be explained on the basis of a reduction in porosity, as evidenced by mercury intrusion porosimetry, as well as by a crack bridging mechanism and by the probable formation of nucleation sites for hydration products, as observed through scanning electron microscopy

    Analytical and numerical analyses of the micromechanics of soft fibrous connective tissues

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    State of the art research and treatment of biological tissues require accurate and efficient methods for describing their mechanical properties. Indeed, micromechanics motivated approaches provide a systematic method for elevating relevant data from the microscopic level to the macroscopic one. In this work the mechanical responses of hyperelastic tissues with one and two families of collagen fibers are analyzed by application of a new variational estimate accounting for their histology and the behaviors of their constituents. The resulting, close form expressions, are used to determine the overall response of the wall of a healthy human coronary artery. To demonstrate the accuracy of the proposed method these predictions are compared with corresponding 3-D finite element simulations of a periodic unit cell of the tissue with two families of fibers. Throughout, the analytical predictions for the highly nonlinear and anisotropic tissue are in agreement with the numerical simulations

    Vertical sleeve gastrectomy lowers SGLT2/Slc5a2 expression in the mouse kidney

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    Bariatric surgery improves glucose homeostasis but the underlying mechanisms are not fully elucidated. Here, we show that the expression of sodium glucose cotransporter-2 (SGLT2/Slc5a2) is reduced in the kidney of lean and obese mice following vertical sleeve gastrectomy (VSG). Indicating an important contribution of altered cotransporter expression to the impact of surgery, inactivation of the SGLT2/Slc5a2 gene by CRISPR/Cas9 attenuated the effects of VSG, with glucose excursions following intraperitoneal injection lowered by ∼30% in wild-type mice but by ∼20% in SGLT2 null animals. The effects of the SGLT2 inhibitor dapaglifozin were similarly blunted by surgery. Unexpectedly, effects of dapaglifozin were still observed in SGLT2 null mice, consistent with the existence of metabolically beneficial off-target effects of SGLT2 inhibitors. Thus, we describe a new mechanism involved in mediating the glucose lowering effects of bariatric surgery

    A rare duplication on chromosome 16p11.2 is identified in patients with psychosis in Alzheimer's disease

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    Epidemiological and genetic studies suggest that schizophrenia and autism may share genetic links. Besides common single nucleotide polymorphisms, recent data suggest that some rare copy number variants (CNVs) are risk factors for both disorders. Because we have previously found that schizophrenia and psychosis in Alzheimer's disease (AD+P) share some genetic risk, we investigated whether CNVs reported in schizophrenia and autism are also linked to AD+P. We searched for CNVs associated with AD+P in 7 recurrent CNV regions that have been previously identified across autism and schizophrenia, using the Illumina HumanOmni1-Quad BeadChip. A chromosome 16p11.2 duplication CNV (chr16: 29,554,843-30,105,652) was identified in 2 of 440 AD+P subjects, but not in 136 AD subjects without psychosis, or in 593 AD subjects with intermediate psychosis status, or in 855 non-AD individuals. The frequency of this duplication CNV in AD+P (0.46%) was similar to that reported previously in schizophrenia (0.46%). This duplication CNV was further validated using the NanoString nCounter CNV Custom CodeSets. The 16p11.2 duplication has been associated with developmental delay, intellectual disability, behavioral problems, autism, schizophrenia (SCZ), and bipolar disorder. These two AD+P patients had no personal of, nor any identified family history of, SCZ, bipolar disorder and autism. To the best of our knowledge, our case report is the first suggestion that 16p11.2 duplication is also linked to AD+P. Although rare, this CNV may have an important role in the development of psychosis

    Orthogonal-view Microscope for the Biomechanics Investigations of Aquatic Organisms

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    Microscopes are essential for biomechanics and hydrodynamical investigation of small aquatic organisms. We report a DIY microscope (GLUBscope) that enables the visualization of organisms from two orthogonal imaging planes (top and side views). Compared to conventional imaging systems, this approach provides a comprehensive visualization strategy of organisms, which could have complex shapes and morphologies. The microscope was constructed by combining custom 3D-printed parts and off-the-shelf components. The system is designed for modularity and reconfigurability. Open-source design files and build instructions are provided in this report. Additionally, proof of use experiments, particularly with Hydra and other organisms that combine the GLUBscope with an analysis pipeline, were demonstrated. Beyond the applications demonstrated, the system can be used or modified for various imaging applications

    Impact of metabolic comorbidity on the association between body mass index and heatlh-related quality of life: a Scotland-wide cross-sectional study of 5,608 participants

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    <p/>Background: The prevalence of obesity is rising in Scotland and globally. Overall, obesity is associated with increased morbidity, mortality and reduced health-related quality of life. Studies suggest that "healthy obesity" (obesity without metabolic comorbidity) may not be associated with morbidity or mortality. Its impact on health-related quality of life is unknown. <p/>Methods: We extracted data from the Scottish Health Survey on self-reported health-related quality of life, body mass index (BMI), demographic information and comorbidity. SF-12 responses were converted into an overall health utility score. Linear regression analyses were used to explore the association between BMI and health utility, stratified by the presence or absence of metabolic comorbidity (diabetes, hypertension, hypercholesterolemia or cardiovascular disease), and adjusted for potential confounders (age, sex and deprivation quintile). <p/>Results: Of the 5,608 individuals, 3,744 (66.8%) were either overweight or obese and 921 (16.4%) had metabolic comorbidity. There was an inverted U-shaped relationship whereby health utility was highest among overweight individuals and fell with increasing BMI. There was a significant interaction with metabolic comorbidity (p = 0.007). Individuals with metabolic comorbidty had lower utility scores and a steeper decline in utility with increasing BMI (morbidly obese, adjusted coefficient: -0.064, 95% CI -0.115, -0.012, p = 0.015 for metabolic comorbidity versus -0.042, 95% CI -0.067, -0.018, p = 0.001 for no metabolic comorbidity). <p/>Conclusions: The adverse impact of obesity on health-related quality of life is greater among individuals with metabolic comorbidity. However, increased BMI is associated with reduced health-related quality of life even in the absence of metabolic comorbidity, casting doubt on the notion of "healthy obesity"

    Exploration of the Eucalyptus globulus gene pool

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    The first Europeans to discover Eucalyptus globulus were French explorers in 1792. Its seed was rapidly spread throughout the world in the 19th century and this was the species by which much of the world first knew the genus. However, it was in the industrial forests of the 20th century that this species, once considered the ‘Prince of Eucalypts’, achieved greatest prominence due to its fast growth and superior pulp qualities. Formal breeding first commenced in 1966 in Portugal and in the late 1980’s large base population trials from open-pollinated seed collections from native stands were established in many countries. These trials have provided unprecedented insights into the quantitative genetic control of numerous traits of economic and ecological importance and how this variation is spatially distributed in the native range of the species. However with large, fully pedigreed breeding populations becoming available for quantitative analysis and the rapidly expanding knowledge of DNA sequence variation, we are now at the threshold of a new understanding of this important eucalypt gene pool. Indications of the significance of non-additive genetic effects are becoming available. The E. globulus chloroplast genome has now been sequenced and several genome maps have been published. Studies of the variation in nuclear microsatellites and the lignin biosynthesis gene CCR confirm the complex, spatially structured nature of the native gene pool. Strong spatial structuring of the chloroplast genome has provided a tool for tracking seed migration and the geographic origin of exotic landraces. Highly divergent lineages of chloroplast DNA have been discovered and studies of the hypervariable JLA+ region argue that some components of the E. globulus gene pool have been assimilated from other species following hybridisation

    Visceral fat area and cardiometabolic risk: The Kardiovize study

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    BACKGROUND: Visceral fat is associated with adiposity-based complications. Bioimpedance measurement allows estimation of visceral fat area (VFA) in an easy manner. However, a validated cut-off value for VFA by bioimpedance associated with cardiometabolic risk is lacking in European population. AIM: To determine cut-off values of VFA measured via bioimpedance associated with cardiometabolic risk. METHODS: Random cross-sectional Czech population-based sample of 25-64 years old subjects. Receiver Operating Characteristic (ROC) curves were used and the area under the curve (AUC), sensitivity, and specificity were calculated. The Cardiometabolic Disease Staging System (CMDS) was used to classify cardiometabolic risk: Stage 1 - 1 or 2 metabolic syndrome (MetS) components, without impaired fasting glucose (IFG); Stage 2 - MetS or IFG; Stage 3 - MetS with IFG; Stage 4 - type 2 diabetes and/or cardiovascular disease. RESULTS: 2052 participants (54.5% females, median age 49 years) were included. Median VFA (inter-quartile range) were 82.2 cm2 (54.8) in men and 89.8 cm2 (55.6) in women. The best VFA cut-offs associated with Stage 1 in men and women were 71 cm2 (sensitivity = 0.654; specificity = 0.427) and 83 cm2 (sensitivity = 0.705; specificity = 0.556) ; Stage 2: 84 cm2 (sensitivity = 0.673; specificity = 0.551) and 98 cm2 (sensitivity = 0.702; specificity = 0.628) ; Stage 3: 90 cm2 (sensitivity = 0.886; specificity = 0.605) and 109 cm2 (sensitivity = 0.755; specificity = 0.704); Stage 4: 91 cm2 (sensitivity = 0.625; specificity = 0.611) and 81 cm2 (sensitivity = 0.695; specificity = 0.448), respectively. CONCLUSION: A cut-off value of VFA of 71 cm2 in men and 83 cm2 in women exhibited the earliest stage of cardiometabolic risk, and 90 cm2 in men and 109 cm2 in women showed the best performance to detect risk
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