81 research outputs found

    Semilocal Convergence for a Fifth-Order Newton's Method Using Recurrence Relations in Banach Spaces

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    We study a modified Newton's method with fifth-order convergence for nonlinear equations in Banach spaces. We make an attempt to establish the semilocal convergence of this method by using recurrence relations. The recurrence relations for the method are derived, and then an existence-uniqueness theorem is given to establish the R-order of the method to be five and a priori error bounds. Finally, a numerical application is presented to demonstrate our approach

    Similarity Analysis of Rebar Corrosion under Different Electrochemical Accelerated Method

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    The concrete cover cracking caused by non-uniform corrosion of reinforcing bar is one of the most important reason for structure service performance degradation. The most widely used electrochemical accelerated corrosion methods include external and internal electrode methods. The reinforcement are used as anode in both methods. The different between two methods is the position of auxiliary. In external electrode method, the auxiliary is set outside the specimen, including three methods, i.e. samples whole/part submerged in saline, samples wrapped by sponge and steel mesh. The electrochemical mechanism of these four accelerated method were analyzed by using the FE software COMSOL. According to the corrosion products distribution characteristic along the rebar circumference, the similarity of electrochemical accelerated and natural corrosion was presented. The results indicated that, rebar corrosion with external electrode method can be regarded as uniform corrosion; the internal electrode method could result in a non-uniform corrosion after optimizing, and the orientation and distance of rebar/electrode are two major influence parameters for accelerated non-uniform corrosion. In addition, based on the corrosion electrochemical principles, a modified internal electrode method was given. The stainless wire was put into the cylinder samples parallel to the rebar as a cathode. In present study, the rapid non-uniform corrosion method can play a positive role in studying the cover cracking process of reinforced concrete

    Characterizing large-scale weak interlayer shear zones using conditional random field theory

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    The shear behavior of large-scale weak intercalation shear zones (WISZs) often governs the stability of foundations, rock slopes, and underground structures. However, due to their wide distribution, undulating morphology, complex fabrics, and varying degrees of contact states, characterizing the shear behavior of natural and complex large-scale WISZs precisely is challenging. This study proposes an analytical method to address this issue, based on geological fieldwork and relevant experimental results. The analytical method utilizes the random field theory and Kriging interpolation technique to simplify the spatial uncertainties of the structural and fabric features for WISZs into the spatial correlation and variability of their mechanical parameters. The Kriging conditional random field of the friction angle of WISZs is embedded in the discrete element software 3DEC, enabling activation analysis of WISZ C2 in the underground caverns of the Baihetan hydropower station. The results indicate that the activation scope of WISZ C2 induced by the excavation of underground caverns is approximately 0.5–1 times the main powerhouse span, showing local activation. Furthermore, the overall safety factor of WISZ C2 follows a normal distribution with an average value of 3.697

    The Effect of the Crosstalk between Photoperiod and Temperature on the Heading-Date in Rice

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    Photoperiod and temperature are two important environmental factors that influence the heading-date of rice. Although the influence of the photoperiod on heading has been extensively reported in rice, the molecular mechanism for the temperature control of heading remains unknown. This study reports an early heading mutant derived from tissue culture lines of rice and investigates the heading-date of wild type and mutant in different photoperiod and temperature treatments. The linkage analysis showed that the mutant phenotype cosegregated with the Hd1 locus. Sequencing analysis found that the mutant contained two insertions and several single-base substitutions that caused a dramatic reduction in Hd1mRNA levels compared with wild type. The expression patterns of Hd1 and Hd3a were also analyzed in different photoperiod and temperature conditions, revealing that Hd1 mRNA levels displayed similar expression patterns for different photoperiod and temperature treatments, with high expression levels at night and reduced levels in the daytime. In addition, Hd1 displayed a slightly higher expression level under long-day and low temperature conditions. Hd3a mRNA was present at a very low level under low temperature conditions regardless of the day-length. This result suggests that suppression of Hd3a expression is a principle cause of late heading under low temperature and long-day conditions

    Presence of qnr gene in Escherichia coli and Klebsiella pneumoniae resistant to ciprofloxacin isolated from pediatric patients in China

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    <p>Abstract</p> <p>Background</p> <p>Quinolone resistance in <it>Enterobacteriaceae </it>results mainly from mutations in type II DNA topoisomerase genes and/or changes in the expression of outer membrane and efflux pumps. Several recent studies have indicated that plasmid-mediated resistance mechanisms also play a significant role in fluoroquinolone resistance, and its prevalence is increasing worldwide. In China, the presence of the <it>qnr </it>gene in the clinical isolates of <it>Enterobacteriaceae </it>has been reported, but this transmissible quinolone resistance gene has not been detected in strains isolated singly from pediatric patients. Because quinolones associated with a variety of adverse side effects on children, they are not authorized for pediatric use. This study therefore aimed to investigate the presence of the <it>qnr </it>gene in clinical isolates of <it>E. coli </it>and <it>K. pneumoniae </it>from pediatric patients in China.</p> <p>Methods</p> <p>A total 213 of non-repetitive clinical isolates resistant to ciprofloxacin from <it>E. coli </it>and <it>K. pneumoniae </it>were collected from hospitalized patients at five children's hospital in Beijing, Shanghai, Guangzhou, and Chongqing. The isolates were screened for the plasmid-mediated quinolone resistance genes of <it>qnrA</it>, <it>qnrB</it>, and <it>qnrS </it>by PCR. Transferability was examined by conjugation with the sodium azide-resistant <it>E. coli </it>J53. All <it>qnr</it>-positive were analyzed for clonality by enterobacterial repetitive intergenic consensus (ERIC)-PCR.</p> <p>Results</p> <p>The study found that 19 ciprofloxacin-resistant clinical isolates of <it>E. coli </it>and <it>K. pneumoniae </it>were positive for the <it>qnr </it>gene, and most of the <it>qnr </it>positive strains were ESBL producers. Conjugation experiments showed that quinolone resitance could be transferred to recipients. Apart from this, different DNA banding patterns were obtained by ERIC-PCR from positive strains, which means that most of them were not clonally related.</p> <p>Conclusion</p> <p>This report on transferable fluoroquinolone resistance due to the <it>qnr </it>gene among <it>E. coli </it>and <it>K. pneumoniae </it>strains indicated that plasmid-mediated quinolone resistance has emerged in pediatric patients in China.</p

    Diagnosis of mixed infection and a primary immunodeficiency disease using next-generation sequencing: a case report

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    Major Histocompatibility Complex Class II (MHC II) deficiency is a rare primary immunodeficiency disorder (PID) with autosomal recessive inheritance pattern. The outcome is almost fatal owing to delayed diagnosis and lacking of effective therapy. Therefore, prompt diagnosis, timely and effective treatment are critical. Here, we report a 117-day-old boy with diarrhea, cough, cyanosis and tachypnea who was failed to be cured by empiric antimicrobial therapy initially and progressed to severe pneumonia and respiratory failure. The patient was admitted to the pediatric intensive care unit (PICU) immediately and underwent a series of tests. Blood examination revealed elevated levels of inflammatory markers and cytomegalovirus DNA. Imaging findings showed signs of severe infection of lungs. Finally, the diagnosis was obtained mainly through next-generation sequencing (NGS). We found out what pathogenic microorganism he was infected via repeated conventional detection methods and metagenomic next-generation sequencing (mNGS) of sputum and bronchoalveolar lavage fluid (BALF). And his whole exome sequencing (WES) examination suggested that CIITA gene was heterozygous mutation, a kind of MHC II deficiency diseases. After aggressive respiratory support and repeated adjustment of antimicrobial regimens, the patient was weaned from ventilator on the 56th day of admission and transferred to the immunology ward on the 60th day. The patient was successful discharged after hospitalizing for 91 days, taking antimicrobials orally to prevent infections post-discharge and waiting for stem cell transplantation. This case highlights the potential importance of NGS in providing better diagnostic testing for unexplained infection and illness. Furthermore, pathogens would be identified more accurately if conventional detection techniques were combined with mNGS

    Unloading of low velocity impact between elastic and elastic-plastic bodies

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    The unloading process of an elastic sphere impacting an elastic-perfectly plastic half-space under low velocity and frictionless conditions is deeply studied in the light of finite element (FE) analysis. The unloading in the FE simulations ranges from elastic-plastic to fully plastic deformation regimes by designed impact velocities and material properties. The cavity profiles after unloading are measured from the FE simulations based on the spherical residual cavity validation. An analytical expression of the radius of spherical residual cavity is derived from the fitting method. The residual radius of curvature is determined by combining its physical definition with the analytical expression. A new revised Hertz unloading model is suggested, which is validated numerically and experimentally

    The fusion of keratinized epithelium, an indication of early implant placement in the aesthetic area: an animal study

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    Abstract Background In the period of the early implant placement, the socket is mainly occupied by provisional matrix (PM). Keratinized epithelium (KE) is critical for primary wound closure. Although both KE and PM are important, the detailed relationship among migrating KE, PM formation and indication of the early implant placement is still unclear. Objective This research aimed to locate a healing stage of KE with highest osteogenic PM formation after tooth extraction, which could be treated as the optimal time point for early implant placement. Material and methods Mice were sacrificed on days 1, 2, 3, 4 and 6 after incisor extraction. Clinical, histological, and immunohistochemical evaluations of the extraction sockets were performed, and statistical analyses were conducted. We then inserted implants into the PM with the greatest bioactivity and observed its osseointegration pattern for 3, 10, 17 and 30 days. Result When KE fusion was reached, sockets were dominated by PM with the greatest expression of osteocalcin (OC, P < 0.05) and high levels of CD34 and Runx2. OC and Runx2 expression were positively correlated with KE coverage (P < 0.05). When the implant was inserted at 4 days’ healing, the PM maintained its osteogenic ability, and osseointegration proceeded perfectly. Conclusion The migration of KE was correlated with the formation of highly osteogenic and angiogenic PM. And the fusion of KE could be treated as an indication for early implant placement

    Prediction of chloride binding isotherms for blended cements

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    Copyright © 2016 Techno-Press, Ltd. A predictive model for chloride binding isotherms of blended cements with various supplementary cementitious materials (SCMs) was established in this work. Totally 560 data points regarding the chloride binding isotherms of 106 various cements were collected from literature. The total amount of bound chloride for each mixture was expressed a combinational function of the predicted phase assemblage and binding isotherms of various hydrated phases. New quantitative expressions regarding the chloride binding isotherms of calcium-silicate-hydrate (C-S-H), AFm, and hydrotalcite phases were provided. New insights about the roles of SCMs on binding capabilities of ordinary portland cements (OPC) were discussed. The proposed model was verified using separate data from different sources and was shown to be reasonably accurate.Link_to_subscribed_fulltex
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