156 research outputs found

    Bond strength of concrete confined by SMA wire jackets

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    AbstractThis study pursuits a goal to assess bond strength of concrete confined by shape memory alloy (SMA) wire jackets that can provide active confinement due to shape memory effect. This study uses NiTiNb SMA wires which show more wider temperature hysteresis than normal NiTi SMA wire. Thus, NiTiNb SMA wires are more applicable for the use of shape memory effect for civil structures which are exposed severe environmental conditions such as large temperature variation. Concrete cylinders of 200 mm × 100 mm (LxD) are used for this study. The SMA wire jackets increases the bond strength of concrete and changes the failure mode from split to pull-out failure. A particular thing in the tests is a split crack developing even with the SMA wire jackets. In general, the crack is not developed in the pull-out mode failure. The SMA wire jackets increase the bonding strength even with the crack developing since it seems that they provide active confinement as well as external passive confinement

    Microstructure and mechanical properties of gas metal arc welded CoCrFeMnNi joints using a 410 stainless steel filler metal

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    Funding Information: JS, JGL and JPO acknowledge Fundação para a Ciência e a Tecnologia (FCT - MCTES ) for its financial support via the project UID/00667/2020 ( UNIDEMI ). JPO acknowledges the funding of CENIMAT/i3N by national funds through the FCT-Fundação para a Ciência e a Tecnologia , I.P., within the scope of Multiannual Financing of R&D Units , reference UIDB/50025/2020-2023 . JS acknowledges the China Scholarship Council for funding the Ph.D. grant ( CSC NO. 201808320394 ). JGL acknowledges Fundação para a Ciência e a Tecnologia (FCT - MCTES ) for funding the Ph.D. Grant 2020.07350.BD . This work was supported by the National Research Foundation of Korea (NRF) with a grant funded by the Korea government ( MSIP ) ( NRF-2021R1A2C3006662 ). The authors acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Beamtime was allocated for proposal I-20210899 EC. The research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020. Funding Information: JS, JGL and JPO acknowledge Fundação para a Ciência e a Tecnologia (FCT - MCTES) for its financial support via the project UID/00667/2020 (UNIDEMI). JPO acknowledges the funding of CENIMAT/i3N by national funds through the FCT-Fundação para a Ciência e a Tecnologia, I.P. within the scope of Multiannual Financing of R&D Units, reference UIDB/50025/2020-2023. JS acknowledges the China Scholarship Council for funding the Ph.D. grant (CSC NO. 201808320394). JGL acknowledges Fundação para a Ciência e a Tecnologia (FCT-MCTES) for funding the Ph.D. Grant 2020.07350.BD. This work was supported by the National Research Foundation of Korea (NRF) with a grant funded by the Korea government (MSIP) (NRF-2021R1A2C3006662). The authors acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Beamtime was allocated for proposal I-20210899 EC. The research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020. Publisher Copyright: © 2022 The AuthorsThe use of filler materials during fusion-based welding processes is widely used to regulate and modify the composition of the welded joints aiming at producing a desired microstructure and/or achieving an improvement in its mechanical performance. Welding of high entropy alloys is still a new topic and the impact of different filler materials on the microstructure and mechanical properties is yet unknown. In this work, gas metal arc welding of the CoCrFeMnNi high entropy alloy using 410 stainless steel as a filler wire was performed. The microstructural evolution of the welded joints was evaluated by optical microscopy, scanning electron microscopy aided by electron backscattered diffraction, high energy synchrotron X-ray diffraction and thermodynamic calculations. Meanwhile, the mechanical behavior of the welded joint, as well as the local mechanical response were investigated with microhardness mapping measurements and with non-contact digital image correlation during tensile loading to failure. The weld thermal cycle promoted solid state reactions in the heat affected zone (recovery, recrystallization and grain growth), which impacted the microhardness across the joint. The role of the 410 stainless steel filler material in the solidification path experienced by the fusion zone was evaluated using Scheil-Gulliver calculations, and a good agreement with the experimentally observed phases was observed. Despite the addition of the 410 stainless steel filler was not conducive to an increase in the fusion zone hardness, the associated bead reinforcement promoted an improvement in both the yield and tensile strengths of the joint compared to a similar weld obtained without filler material (355 vs 284 MPa and 641 vs 519 MPa, respectively). This allows to infer that the addition of filler materials for welding high entropy alloys is a viable method for the widespread use of these novel materials. In this work, by coupling microstructure and mechanical property characterization, a correlation between the processing conditions, microstructure and mechanical properties was obtained providing a wider basis for promoting the application of gas metal arc welding of high entropy alloys for industrial applications.publishersversionpublishe

    Microstructure and mechanical properties of gas metal arc welded CoCrFeMnNi joints using a 308 stainless steel filler metal

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    Funding Information: JS, JGL and JPO acknowledge Fundação para a Ciência e a Tecnologia (FCT - MCTES) for its financial support via the project UID/00667/2020 (UNIDEMI). JPO acknowledges funding by national funds from FCT - Fundação para a Ciência e a Tecnologia, I.P., in the scope of the projects LA/P/0037/2020, UIDP/50025/2020 and UIDB/50025/2020 of the Associate Laboratory Institute of Nanostructures, Nanomodelling and Nanofabrication – i3N. JS acknowledges the China Scholarship Council for funding the Ph.D. grant (CSC NO. 201808320394). JGL acknowledges Fundação para a Ciência e a Tecnologia (FCT-MCTES) for funding the Ph.D. Grant 2020.07350.BD. This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (NRF-2022R1A5A1030054). The authors acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Beamtime was allocated for proposal I-20210899 EC. The research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020. Funding Information: JS, JGL and JPO acknowledge Fundação para a Ciência e a Tecnologia (FCT - MCTES) for its financial support via the project UID/00667/2020 (UNIDEMI). JPO acknowledges funding by national funds from FCT - Fundação para a Ciência e a Tecnologia, I.P. , in the scope of the projects LA/P/0037/2020 , UIDP/50025/2020 and UIDB/50025/2020 of the Associate Laboratory Institute of Nanostructures, Nanomodelling and Nanofabrication – i3N. JS acknowledges the China Scholarship Council for funding the Ph.D. grant (CSC NO. 201808320394 ). JGL acknowledges Fundação para a Ciência e a Tecnologia (FCT-MCTES) for funding the Ph.D. Grant 2020.07350.BD . This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) ( NRF-2022R1A5A1030054 ). The authors acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Beamtime was allocated for proposal I-20210899 EC. The research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020. Publisher Copyright: © 2022 The AuthorsIn this paper, gas metal arc welding of a CoCrFeMnNi high entropy alloy was performed using 308 stainless steel filler wire. Electron backscatter diffraction and synchrotron X-ray diffraction were used to determine the microstructural evolution, while microhardness mapping and non-contact digital image correlation were employed to assess the local mechanical response across the welded joints. Further, thermodynamic calculations were implemented to support the understanding of the microstructure evolution. Through a systematic analysis of the microstructure evolution and mechanical properties, it is established a correlation between welding process, microstructure and mechanical properties. Besides, this work lays the foundations for the use of low-cost arc-based welding technologies for successful joining and application of welded joints based on high entropy alloys.publishersversionpublishe

    Deformation behavior and strengthening effects of an eutectic AlCoCrFeNi2.1 high entropy alloy probed by in-situ synchrotron X-ray diffraction and post-mortem EBSD

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    Funding Information: JS, JGL, and JPO acknowledge Fundação para a Ciência e a Tecnologia (FCT - MCTES) for its financial support via the project UID/00667/2020 (UNIDEMI). JS acknowledges the China Scholarship Council for funding the Ph.D. grant (CSC NO. 201808320394). JGL acknowledges FCT – MCTES for funding the Ph.D. grant 2020.07350.BD. JPO acknowledges funding by national funds from FCT - Fundação para a Ciência e a Tecnologia, I.P. in the scope of the projects LA/P/0037/2020, UIDP/50025/2020 of the Associate Laboratory Institute of Nanostructures, Nanomodelling and Nanofabrication – i3N. The authors acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Beamtime was allocated for proposal I-20210899 EC. The research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872from the EU Framework Programme for Research and Innovation HORIZON 2020. HSK acknowledges the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (NRF-2021R1A2C3006662, NRF-2022R1A5A1030054). Yeon Taek Choi was supported by the Basic Science Research Program “Fostering the Next Generation of Researcher” through the NRF funded by the Ministry of Education [grant number 2022R1A6A3A13073824]. The raw/processed data required to reproduce the above findings cannot be shared at this time as the data also forms part of an ongoing study. Funding Information: JS, JGL, and JPO acknowledge Fundação para a Ciência e a Tecnologia (FCT - MCTES) for its financial support via the project UID/00667/2020 (UNIDEMI). JS acknowledges the China Scholarship Council for funding the Ph.D. grant (CSC NO. 201808320394 ). JGL acknowledges FCT – MCTES for funding the Ph.D. grant 2020.07350.BD . JPO acknowledges funding by national funds from FCT - Fundação para a Ciência e a Tecnologia , I.P., in the scope of the projects LA/P/0037/2020 , UIDP/50025/2020 and UIDB/50025/2020 of the Associate Laboratory Institute of Nanostructures, Nanomodelling and Nanofabrication – i3N. The authors acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Beamtime was allocated for proposal I-20210899 EC. The research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020 . HSK acknowledges the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) ( NRF-2021R1A2C3006662 , NRF-2022R1A5A1030054 ). Yeon Taek Choi was supported by the Basic Science Research Program “Fostering the Next Generation of Researcher” through the NRF funded by the Ministry of Education [grant number 2022R1A6A3A13073824 ]. Publisher Copyright: © 2023 The AuthorsIn this work, high energy synchrotron X-ray diffraction was used during tensile testing of an as-cast eutectic AlCoCrFeNi2.1 high entropy alloy. Aside, from determining for the first time the volume fractions of existing phases, we further detail their role on the alloy deformation behavior. The two major phases, a soft disordered FCC and a hard ordered B2 BCC, were observed to exhibit a stress partitioning effect which can be used to modulate the mechanical response of the material based on the relative volume fraction of each phase. Dislocation density analysis revealed that the soft FCC phase had a significantly higher dislocation density right after the onset of plastic deformation. This is attributed to the existence of strain gradients across the lamellar structure, where the hard B2 BCC prevents free deformation of the FCC phase. Nonetheless, despite the increase of the dislocation density in the soft FCC phase, calculations of the strengthening effects induced by generation of dislocations are more significant in the hard B2 BCC phases, as this phase is primarily responsible for the strength increase in the alloy. Besides, the evolutions in dislocation density of the soft FCC and hard B2 BCC phases during tensile deformation obtained from synchrotron X-ray diffraction data are consistent with the evolution of KAM determined by EBSD characterization. Also, lattice strain analysis across two principal directions (parallel and perpendicular to the loading axis) reveals that for these specific orientations there is a preferential deformation of the hard FCC planes which can be related to the deformation response of specific lattice planes at distinct orientations, as well as to the phase partitioning stress behavior.publishersversionpublishe

    A Case of Colovesical Fistula Induced by Sigmoid Diverticulitis

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    Colonic diverticulosis has continuously increased, noticeably left-sided diseases, in Korea. A colovesical fistula is an uncommon complication of diverticulitis, and its most common cause is diverticular disease. Confirmation of its presence generally depends on clinical findings, such as pneumaturia and fecaluria. The primary aim of a diagnostic workup is not to observe the fistular tract itself but to find the etiology of the disease so that an appropriate therapy can be initiated. We present here the case of a 79-year-old man complaining of pneumaturia and fecaluria. On abdomen and pelvis CT, the patient was diagnosed as having a colovesical fistula due to sigmoid diverticulitis. After division of the adhesion between the sigmoid colon and the bladder, the defect of the bladder wall was repaired by simple closure. The colonic defect was treated with a segmental resection, including the rectosigmoid junction. The patient is doing well at 6 months after the operation and shows no evidence of recurrence of the fistula

    Urachal Actinomycosis Mimicking a Urachal Tumor

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    A 26-year-old man presented with lower abdominal discomfort and a palpable mass in the right lower quadrant. An abdominal computed tomography (CT) scan revealed an abdominal wall mass that extended from the dome of the bladder. Fluorine-18 fluorodeoxyglucose (FDG) positron-emission tomography/CT (PET/CT) showed hypermetabolic wall thickening around the bladder dome area that extended to the abdominal wall and hypermetabolic mesenteric infiltration. Differential diagnosis included a urachal tumor with invasion into adjacent organs and chronic inflammatory disease. Partial cystectomy with abdominal wall mass excision was performed, and the final pathologic report was consistent with urachal actinomycosis

    Prediction for serious bacterial infection in febrile children aged 3 years or younger: comparison of inflammatory markers, the Laboratory-score, and a new laboratory combined model

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    Purpose To compare the efficacy of inflammatory markers, the Laboratory-score, and a new laboratory combined model for predicting serious bacterial infection (SBI) in young febrile children. Methods The presence of SBI was reviewed in previously healthy children aged 3 years or younger with fever (> 38℃) who visited the emergency department from 2017 through 2018. Areas under the curves (AUCs) of the receiver operating characteristic curve for SBI were compared with individual inflammatory markers (white blood cells [WBC] count, erythrocyte sedimentation rate [ESR], C-reactive protein [CRP], procalcitonin [PCT], and urine WBC count), the Laboratory-score, and a laboratory combined model. The latter model was developed using logistic regression analysis including ESR, CRP, and PCT. Results Of the 203 enrolled children, SBI was diagnosed in 58 (28.6%). For SBI prediction, the Laboratory-score showed 51.7% sensitivity (95% confidence interval [CI], 38.2%-65.0%) and 83.5% specificity (95% CI, 76.4%-89.1%). The AUC of the Laboratory-score (0.76) was significantly superior to the values of all individual inflammatory markers (WBC, 0.59 [P = 0.032]; ESR, 0.69; and CRP, 0.74 [P < 0.001]) except that of PCT (0.77, [P < 0.001]). The AUC of the laboratory combined model (0.80) was superior to that of the Laboratory-score (0.76) (P < 0.001). Conclusion In this study, the new laboratory combined model showed good predictability for SBI. This finding suggests the usefulness of combining ESR, CRP, and PCT in predicting SBI

    Factors associated with hospitalization via emergency department in children with acute bronchiolitis

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    Purpose In infants and young children, acute bronchiolitis is a leading cause of hospitalization via emergency departments (EDs). We aimed to investigate factors associated with hospitalization via ED in children with acute bronchiolitis. Methods We reviewed medical records of children aged 36 months or younger with acute bronchiolitis who visited the ED from January to December 2017. The following clinical data were collected and analyzed: age, sex, premature birth history, symptoms, fever duration, presence of respiratory distress and radiographic lesion, and inflammatory markers. Results Of 780 children enrolled, 463 (59.4%) were hospitalized via the ED. The factor associated with the hospitalization were age ≤ 12 months (odd ratio [OR], 45.34; confidence interval [CI], 17.50-117.44), fever lasting ≥ 3 days (OR, 13.66; 95% CI, 6.46-28.87), respiratory rate ≥ 24 breaths per minute (OR, 6.88; 95% CI, 4.21-11.26), radiographic lesion (OR, 5.70; 95% CI 2.62-12.40), and chest retraction (OR, 2.45; 95% CI, 1.11-5.41). Conclusion In children with acute bronchiolitis who visit EDs, those having younger age, longer fever duration, respiratory distress or radiographic lesion may need hospitalization

    Autoimmune Hypoglycemia in a Patient with Characterization of Insulin Receptor Autoantibodies

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    BackgroundType B insulin resistance syndrome is a manifestation of autoantibodies to the insulin receptor that results in severe hyperglycemia and acanthosis nigricans. However, the mechanisms by which these autoantibodies induce hypoglycemia are largely unknown. In this paper, we report the case of patient with type B insulin resistance syndrome who presented with frequent severe fasting hypoglycemia and acanthosis nigricans.MethodsTo evaluate the mechanism of hypoglycemia, we measured the inhibition of insulin binding to erythrocytes and IM9 lymphocytes in a sample of the patient's dialyzed serum before and after immunosuppressive therapy.ResultsIn the patient's pre-treatment serum IgG, the binding of 125I-insulin to erythrocytes was markedly inhibited in a dose-dependent manner until the cold insulin level reached 10-9 mol/L. We also observed dose-dependent inhibition of insulin binding to IM9 lymphocytes, which reached approximately 82% inhibition and persisted even when diluted 1:20. After treatment with glucocorticoids, insulin-erythrocyte binding activity returned to between 70% and 80% of normal, while the inhibition of insulin-lymphocyte binding was reduced by 17%.ConclusionWe treated a patient with type B insulin resistance syndrome showing recurrent fasting hypoglycemia with steroids and azathioprine. We characterized the patient's insulin receptor antibodies by measuring the inhibition of insulin binding
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