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Wyszukujesz frazę "Arman, A." wg kryterium: Autor


Tytuł:
Effects of alkali solution concentration and soaking time on mechanical properties of coconut fibre
Autorzy:
Kondo, Y.
Arsyad, M.
Ahmad, A.
Soenoko, R.
Arman, A.
Tematy:
coir
soaking
alkali
interfacial
shear
włókno kokosowe
moczenie
alkalia
ścinanie
Pokaż więcej
Wydawca:
Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
Powiązania:
https://bibliotekanauki.pl/articles/59116148.pdf  Link otwiera się w nowym oknie
Opis:
Purpose: The study aims to determine the effect of the treatment of alkali solution concentration and soaking time on the mechanical properties of coconut fibre. Design/methodology/approach: The study consists of preparing materials and equipment, immersion of coconut fibre in an alkali solution, drying in a furnace, testing, analysis of test results, and conclusions. Materials and equipment used are coconut fibre, alkali solution, polyester matrix, distilled water, furnace, hydrolysis test, tensile test, and SEM analysis. The sample had two treatments; the first was coconut fibre, which was soaked in the sodium hydroxide solution with 5%, 10%, 15%, and 20% concentrations for 3 hours. The second treatment was coconut fibre soaked in the sodium hydroxide solution with a concentration of 20% for 1, 5, 7, 9, and 11 hours. The samples were then dried in a furnace at 90ºC for 5 hours, and then a hydrolysis test, tensile test, pull-out test, and SEM analysis were carried out. Findings: The results suggest that for immersion in an alkali solution of 20%, the highest tensile strength of coconut coir fibre was obtained in soaking for 3 hours at 280.94 N/mm2, and the highest bonding strength between coconut coir fibres with a matrix polyester was obtained at 5 hours immersion at 7.86 N/mm2. Research limitations/implications: In the given study, coconut fibre was treated by soaking it in 5%, 10%, 15%, and 20% sodium hydroxide solution. Then, a single fibre tensile test was carried out, and a pull-out test was carried out to determine the mechanical properties of coconut fibre as a required effect that had been given. Subsequent studies can be carried out with other treatments using other chemical solutions, such as hydrogen peroxide or potassium permanganate. Originality/value: The tensile strength of coconut fibre without treatment was 186.42 N/mm2, whereas after being immersed in 20% sodium hydroxide solution, the tensile strength became 280.94 N/mm2. Likewise, the shear strength of the interface between the fibre and the polyester matrix was 1.85 N/mm2 for untreated coconut fibre to 3.09 N/mm2 for coconut fibre soaked in a 20% sodium hydroxide solution. The results of the study are intended as data for the use of coconut fibre as a natural fibre-reinforced composite material, for example, as a raw material for fishing boat walls.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Trend Detection in Climate Change Indicators Using Non-Parametric Statistics: A Case Study of Abu Dhabi, United Arab Emirates
Autorzy:
Basarir, A.
Arman, H.
Hussein, S.
Murad, A.
Aldahan, A.
Abdulla Al-Abri, M.
Tematy:
92.70.Kb
92.05.Df
Pokaż więcej
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:
https://bibliotekanauki.pl/articles/1031779.pdf  Link otwiera się w nowym oknie
Opis:
This study focuses on detecting trends for climate change indicators, such as average monthly temperature, rainfall, humidity, and wind speed for fourteen stations located between Al Ain and Abu Dhabi cities of the United Arab Emirates. Mann-Kendall non-parametric test was run on monthly time series data for the period 2003-2015 with consideration of seasonality. Significant increasing/decreasing trends in rainfall (for four stations), humidity (for six stations), and wind speed (for nine stations) were detected while no significant trend was observed in temperature for all stations.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mitral valve surgery after failed transcatheter edge-to-edge repair
Autorzy:
Greason, Kevin
Alkhouli, Mohamad
Schaff, Hartzell V.
Mazur, Piotr
Zheng, Clark
Arghami, Arman
Crestanello, Juan A.
Dearani, Joseph
Daly, Richard C.
Opis:
Objective: Mitral valve operations for failed transcatheter edge-to-edge repair (TEER) are increasing. This study investigated the indications, surgical procedures, and outcomes after surgery for failed TEER. Methods: We analyzed records of patients who underwent mitral valve operations after TEER between January 2013 and September 2021. Patient characteristics, clip number and location, indications, timing, surgery type, and outcomes were evaluated. Results: A total of 41 patients (median age, 77 years; 14 women; median Society of Thoracic Surgeons predicted risk of mortality score, 9.4% [5.6%-12.6%]; and previous cardiac surgery in 21 patients) underwent mitral valve surgery at a median of 8 months (range, 4-16 months) after TEER. One clip was implanted in 24 patients and 2 or more in 17 patients. Indications for surgery were severe mitral regurgitation in 33, severe mitral stenosis in 1 patient, and both in 7 patients. Operations were performed via sternotomy in 37 patients and lateral thoracotomy in 4 patients. The mitral valve was replaced in all patients (bioprosthesis in 35 patients and a mechanical valve in 6 patients). Concomitant procedures were performed in 30 patients. Operative mortality was 5% (observed to expected ratio, 0.53) and did not differ for primary procedures versus reoperations. Echocardiographic follow-up demonstrated no or trivial mitral regurgitation in 34 patients, mild mitral regurgitation in 5 patients, and moderate perivalvular mitral regurgitation in 1 patient with severe mitral annular calcification. At a median follow-up of 1.5 years (interquartile range, 4.7 months-2.7 years), the actuarial survival was 79%. Conclusions: Mitral valve replacement can be performed safely after failed TEER with operative mortality lower than expected even in high-risk patients.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Artykuł
Tytuł:
Mitral valve surgery for persistent or recurrent mitral regurgitation after transcatheter edge-to-edge repair is associated with improved survival
Autorzy:
Mazur, Piotr
El Shaer, Ahmed
Arghami, Arman
Eleid, Mackram F.
Greason, Kevin
Chavez Ponce, Alejandra
Crestanello, Juan A.
Guerrero, Mayra
Alkhouli, Mohamad
Rihal, Charanjit S.
Opis:
Background: The management of severe mitral regurgitation (MR) after transcatheter edge‐to‐edge repair (TEER) remains a clinical conundrum. Considering the growing volume of TEER, more outcomes data for mitral surgery in this cohort are needed. Methods and Results: Symptomatic patients with persistent or recurrent severe MR after TEER evaluated between May 2014 and June 2021 were included. The primary outcome was all‐cause mortality in patients who were treated with surgery versus medical therapy. The Kaplan–Meier and Cox regression methods were used to report risk‐adjusted survival analyses. Among the 142 included patients, 44 (31.0%) underwent mitral surgery. Patients who underwent surgery were younger than those treated medically (74.1±8.9 versus 78.6±10.5 years, P=0.01). Major comorbidities were similar except obesity, sleep apnea, left ventricular dimensions, and ejection fraction. Society of Thoracic Surgeons Predicted Risk of Operative Mortality was 9.0±4.7 versus 7.9±4.9 in the surgical versus medical therapy groups, respectively, P=0.22. Time from TEER to detection of severe MR was similar in both groups (median [interquartile range] 97.5 [39.5–384] versus 93.5 [40–389] days in the surgical versus medical groups, respectively [P>0.05]). In the surgical group, valve replacement was performed in all patients. Operative mortality was 4.5% (observed/expected ratio 0.55), and major complications were uncommon. After risk‐adjustment, surgery was associated with significantly lower all‐cause mortality (adjusted hazard ratio, 0.33 [95% CI, 0.12–0.92], P=0.001) compared with medial therapy.: Conclusions: Compared with medical therapy, mitral surgery in patients with severe persistent or recurrent MR after TEER is associated with lower mortality despite the high‐risk profile of these patients. Patients with severe MR after TEER should be considered for surgery at a referral mitral surgical center.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Artykuł

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