1,232 research outputs found

    Experiment Analysis of Concrete’s Mechanical Property Deterioration Suffered Sulfate Attack and Drying-Wetting Cycles

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    The mechanism of concrete deterioration in sodium sulfate solution is investigated. The macroperformance was characterized via its apparent properties, mass loss, and compressive strength. Changes in ions in the solution at different sulfate attack periods were tested by inductively coupled plasma (ICP). The damage evolution law, as well as analysis of the concrete’s meso- and microstructure, was revealed by scanning electron microscope (SEM) and computed tomography (CT) scanning equipment. The results show that the characteristics of concrete differed at each sulfate attack period; the drying-wetting cycles generally accelerated the deterioration process of concrete. In the early sulfate attack period, the pore structure of the concrete was filled with sulfate attack products (e.g., ettringite and gypsum), and its mass and strength increased. The pore size and porosity decreased while the CT number increased. As deterioration progressed, the swelling/expansion force of products and the salt crystallization pressure of sulfate crystals acted on the inner wall of the concrete to accumulate damage and accelerate deterioration. The mass and strength of concrete sharply decreased. The number and volume of pores increased, and the pore grew more quickly resulting in initiation and expansion of microcracks while the CT number decreased

    Theory of differential inclusions and its application in mechanics

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    The following chapter deals with systems of differential equations with discontinuous right-hand sides. The key question is how to define the solutions of such systems. The most adequate approach is to treat discontinuous systems as systems with multivalued right-hand sides (differential inclusions). In this work three well-known definitions of solution of discontinuous system are considered. We will demonstrate the difference between these definitions and their application to different mechanical problems. Mathematical models of drilling systems with discontinuous friction torque characteristics are considered. Here, opposite to classical Coulomb symmetric friction law, the friction torque characteristic is asymmetrical. Problem of sudden load change is studied. Analytical methods of investigation of systems with such asymmetrical friction based on the use of Lyapunov functions are demonstrated. The Watt governor and Chua system are considered to show different aspects of computer modeling of discontinuous systems

    Neuropsychiatric disturbance detecting polycythemia vera myelofibrosis: a case report and literature review

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    BackgroundNeuropsychiatric disturbances and chorea are less recognized consequences of polycythemia vera (PV), and their role in post-PV myelofibrosis (MF) has not been reported. Clinical features that predict post-PV MF lack specificity.Case presentationWe describe an elderly patient with PV who developed acute-onset reversible neuropsychiatric disturbances accompanied by generalized chorea and was finally diagnosed with post-PV MF after a bone marrow examination. We also reviewed four cases of late PV associated with neuropsychiatric symptoms since 1966 and analyzed their clinical characteristics and therapeutic effects.ConclusionOur case indicates that Janus kinase 2 (JAK2)-related PV is a treatable cause of late-onset chorea and that chorea may herald the deterioration of hematological parameters. Our case provides a clinically specific representation of post-PV MF. Patients with a long course of PV are recommended to undergo bone marrow re-examinations when they present with neuropsychiatric symptoms to achieve an early diagnosis of post-PV MF

    Hidden attractors in fundamental problems and engineering models

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    Recently a concept of self-excited and hidden attractors was suggested: an attractor is called a self-excited attractor if its basin of attraction overlaps with neighborhood of an equilibrium, otherwise it is called a hidden attractor. For example, hidden attractors are attractors in systems with no equilibria or with only one stable equilibrium (a special case of multistability and coexistence of attractors). While coexisting self-excited attractors can be found using the standard computational procedure, there is no standard way of predicting the existence or coexistence of hidden attractors in a system. In this plenary survey lecture the concept of self-excited and hidden attractors is discussed, and various corresponding examples of self-excited and hidden attractors are considered

    High energy density in silver niobate ceramics

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    crosscheck: This document is CrossCheck deposited related_data: Supplementary Information copyright_licence: The Royal Society of Chemistry has an exclusive publication licence for this journal history: Received 26 July 2016; Accepted 16 August 2016; Accepted Manuscript published 17 August 2016crosscheck: This document is CrossCheck deposited related_data: Supplementary Information identifier: Nadezda V. Tarakina (ORCID) copyright_licence: The Royal Society of Chemistry has an exclusive publication licence for this journal history: Received 26 July 2016; Accepted 16 August 2016; Accepted Manuscript published 17 August 2016; Advance Article published 6 September 2016crosscheck: This document is CrossCheck deposited related_data: Supplementary Information identifier: Nadezda V. Tarakina (ORCID) copyright_licence: The Royal Society of Chemistry has an exclusive publication licence for this journal history: Received 26 July 2016; Accepted 16 August 2016; Accepted Manuscript published 17 August 2016; Advance Article published 6 September 2016National Basic Research Program of China (973 Program) under Grant No. 2015CB654602, the International Science & Technology Cooperation Program of China (Grant No. 2013DFR50470), the Natural Science Basis Research Plan in Shaanxi Province of China (Grant No. 2015JM5199), the Fundamental Research Funds for the Central Universities, and “111” Project (No. B14040). In particular, Ye Tian acknowledges the nancial support from the China Scholarship Council

    Wolbachia and DNA barcoding insects: patterns, potential and problems

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    Wolbachia is a genus of bacterial endosymbionts that impacts the breeding systems of their hosts. Wolbachia can confuse the patterns of mitochondrial variation, including DNA barcodes, because it influences the pathways through which mitochondria are inherited. We examined the extent to which these endosymbionts are detected in routine DNA barcoding, assessed their impact upon the insect sequence divergence and identification accuracy, and considered the variation present in Wolbachia COI. Using both standard PCR assays (Wolbachia surface coding protein – wsp), and bacterial COI fragments we found evidence of Wolbachia in insect total genomic extracts created for DNA barcoding library construction. When >2 million insect COI trace files were examined on the Barcode of Life Datasystem (BOLD) Wolbachia COI was present in 0.16% of the cases. It is possible to generate Wolbachia COI using standard insect primers; however, that amplicon was never confused with the COI of the host. Wolbachia alleles recovered were predominantly Supergroup A and were broadly distributed geographically and phylogenetically. We conclude that the presence of the Wolbachia DNA in total genomic extracts made from insects is unlikely to compromise the accuracy of the DNA barcode library; in fact, the ability to query this DNA library (the database and the extracts) for endosymbionts is one of the ancillary benefits of such a large scale endeavor – for which we provide several examples. It is our conclusion that regular assays for Wolbachia presence and type can, and should, be adopted by large scale insect barcoding initiatives. While COI is one of the five multi-locus sequence typing (MLST) genes used for categorizing Wolbachia, there is limited overlap with the eukaryotic DNA barcode region

    Kinetic regulation of multi-ligand binding proteins

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    Background: Second messengers, such as calcium, regulate the activity of multisite binding proteins in a concentration-dependent manner. For example, calcium binding has been shown to induce conformational transitions in the calcium-dependent protein calmodulin, under steady state conditions. However, intracellular concentrations of these second messengers are often subject to rapid change. The mechanisms underlying dynamic ligand-dependent regulation of multisite proteins require further elucidation. Results: In this study, a computational analysis of multisite protein kinetics in response to rapid changes in ligand concentrations is presented. Two major physiological scenarios are investigated: i) Ligand concentration is abundant and the ligand-multisite protein binding does not affect free ligand concentration, ii) Ligand concentration is of the same order of magnitude as the interacting multisite protein concentration and does not change. Therefore, buffering effects significantly influence the amounts of free ligands. For each of these scenarios the influence of the number of binding sites, the temporal effects on intermediate apo- and fully saturated conformations and the multisite regulatory effects on target proteins are investigated. Conclusions: The developed models allow for a novel and accurate interpretation of concentration and pressure jump-dependent kinetic experiments. The presented model makes predictions for the temporal distribution of multisite protein conformations in complex with variable numbers of ligands. Furthermore, it derives the characteristic time and the dynamics for the kinetic responses elicited by a ligand concentration change as a function of ligand concentration and the number of ligand binding sites. Effector proteins regulated by multisite ligand binding are shown to depend on ligand concentration in a highly nonlinear fashion

    Tumour Suppressive Function and Modulation of Programmed Cell Death 4 (PDCD4) in Ovarian Cancer

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    Background: Programmed cell death 4 (PDCD4), originally identified as the neoplastic transformation inhibitor, was attenuated in various cancer types. Our previous study demonstrated a continuous down-regulation of PDCD4 expression in the sequence of normal-borderline-malignant ovarian tissue samples and a significant correlation of PDCD4 expression with disease-free survival. The objective of the current study was to further investigate the function and modulation of PDCD4 in ovarian cancer cells. Principal Findings: We demonstrated that ectopic PDCD4 expression significantly inhibited cell proliferation by inducing cell cycle arrest at G1 stage and up-regulation of cell cycle inhibitors of p27 and p21. Cell migration and invasion were also inhibited by PDCD4. PDCD4 over-expressing cells exhibited elevated phosphatase and tensin homolog (PTEN) and inhibited protein kinase B (p-Akt). In addition, the expression of PDCD4 was up-regulated and it was exported to the cytoplasm upon serum withdrawal treatment, but it was rapidly depleted via proteasomal degradation upon serum re-administration. Treatment of a phosphoinositide 3-kinase (PI3K) inhibitor prevented the degradation of PDCD4, indicating the involvement of PI3K-Akt pathway in the modulation of PDCD4. Conclusion: PDCD4 may play a critical function in arresting cell cycle progression at key checkpoint, thus inhibiting cell proliferation, as well as suppressing tumour metastasis. The PI3K-Akt pathway was implied to be involved in the regulatio

    Non-Medical Financial Burden in Tuberculosis Care: a Cross-Sectional Survey in Rural China

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    Background: Treatment of tuberculosis (TB) in China is partially covered by national programs and health insurance schemes, though TB patients often face considerable medical expenditures. For some, especially those from poorer households, non-medical costs, such as transport, accommodation, and nutritional supplementation may be a substantial additional burden. In this article we aim to evaluate these non-medical costs induced by seeking TB care using data from a large scale cross-sectional survey. Methods: A total of 797 TB cases from three cities were randomly selected using a stratified cluster sampling design. Inpatient medical costs, outpatient medical costs, and direct non-medical costs related to TB treatment were collected using in-person interviews by trained interviewers. Mean and median non-medical costs for different sub-groups were calculated and compared using Kruskal-Wallis and Mann–Whitney U tests. Regression analysis was conducted to assess the influence of different patient characteristics on total non-medical cost. Results: The median non-medical cost was RMB 1429, with interquartile range RMB 424–2793. The median non-medical costs relating to inpatient treatment, outpatient treatment, and additional nutrition supplementation were RMB 540, 91, and 900, respectively. Of the 797 cases, 20 % reported catastrophic expenditure on non-medical costs. Statistically significant differences were detected between different cities, age groups, geographical locations, inpatient/outpatient care, education levels and family income groups. Conclusions: Non-medical costs relating to TB treatment are a serious financial burden for many TB patients. Financial assistance that can limit this burden is urgently needed during the treatment period, especially for the poor

    Management of venous thrombosis in fibular free osseomusculocutaneous flaps used for mandibular reconstruction: clinical techniques and treatment considerations

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    <p>Abstract</p> <p>Background</p> <p>Mandibular reconstruction by means of fibula transplants is the standard therapy for severe bone loss after subtotal mandibulectomy. Venous failure still represents the most common complication in free flap surgery. We present the injection of heparine into the arterial pedicle as modification of the revising both anastomoses in these cases and illustrate the application with a clinical case example.</p> <p>Methods</p> <p>Methods consist of immediate revision surgery with clot removal, heparin perfusion by direct injection in the arterial vessel of the pedicle, subsequent high dose low-molecular weight heparin therapy, and leeches. After 6 hours postoperatively, images of early flap recovery show first sings of recovery by fading livid skin color.</p> <p>Results</p> <p>The application of this technique in a patient with venous thrombosis resulted in the complete recovery of the flap 60 hours postoperatively. Other cases achieved similar success without additional lysis Therapy or revision of the arterial anastomosis.</p> <p>Conclusion</p> <p>Rescue of fibular flaps is possible even in patients with massive thrombosis if surgical revision is done quickly.</p
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