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Use of Thixoforming as a Manufacturing Method for Metallic Composites
Hüsnügül Yilmaz Atay,David Aišman,Hana Jirková,Mária Behulova,Bohuslav Mašek 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.9
Thixoforming is one of the members of the family of semi-solid forming processes. It is possible to obtain complex shapeof materials by this method and unconventional microstructures can be achieved due to its thixotropic properties. However,in this study thixoforming was used not only as forming method but also as a manufacturing method. Metallic compositeswere manufactured by a process of integration of powder metallurgy and semi-solid production technique. The mixture ofCo72.5B15Si12.5alloy and Fe powders become partially melted, compressed mechanically in semi-solid state and filled intricatecavities. Without changing alloy structure, it could be possible to reinforce it with Fe powders. Moreover, the final shapeof the product could be achieved at the same time. Prior to the process, Co72.5B15Si12.5alloy obtained in the form of stickwas characterized by X-ray diffraction (XRD), scanning electron microscopy–energy dispersive spectroscopy (SEM–EDX),differential thermal analysis-thermogravimetry (DTA-TG), light microscope and micro-hardness machine. The stick wasmilled to get alloy powders and they were blended with iron. Characterization of the structures of the composite materialwas performed. It was concluded that the heating process of iron and alloy powders provides the formation of compact metalmatrix composites.
Erbaş Derya,Ünlü Hüsnü,Ünlü Halime,Koyuncu Mehmet Ali 한국원예학회 2024 Horticulture, Environment, and Biotechnology Vol.65 No.2
In the present study, it was aimed to determine the eff ects of preharvest oxalic acid (OA) treatments on the biochemical content and quality of minimally processed leeks during storage. For this purpose, leeks were treated with solutions con taining 0 (control), 1, 2 and 3 mM OA and 0.1% Tween-20 with a pump 6, 4 and 2 weeks before harvest. The packaged leeks were stored at 0 °C and 90 ± 5% relative humidity (RH) for 50 days. After the cold storage, the leeks were kept at 20 °C and 60 ± 5% RH for 3 days to determine the shelf-life. The eff ects of OA treatments on the weight loss, external appearance and bioactive compounds were remarkable. At the end of storage, the losses of ascorbic acid (AsA) content were determined as 55.53% in the control group and 22.89% in the 3 mM OA treatment. Similarly, the decrease in total phenolic (TP) content and antioxidant activity (AOA) in the control group was 37.34% and 45.70%, respectively, while these values were determined as 26.94% and 32.65% in the 3 mM OA treatment, respectively. With 3 mM OA treatment, the high dose in this study, the AsA, TP, and AOA contents of leeks were better preserved. The change in the external appearance scores at the end of cold storage was determined as 46.33% in the control group whereas it was determined between 31.44% (2 mM OA) and 42.55% (1 mM OA) in OA treatments. As a result, OA-treated and minimally processed leeks were successfully stored for 50 days at 0 °C and 90 ± 5% RH. Moreover, the effi cacy of OA increased in a dose dependent manner in the study.
DenizUykun Mangaloğlu,Murat Baranak,Özlem Ataç,Hüsnü Atakül 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.66 No.-
The effects of alkali promoters namely potassium, copper, and manganese, on the performance of the bi-functional iron–low acidity ZSM-5 catalysts in the Fischer–Tropsch (FT) synthesis were studied. ZSM-5 with very high silica alumina ratio (SAR) of 280 was used to take advantage of its shape selectivity and suppressing the effect of alkali migration on zeolite cation exchange sites. One bi-functional iron base catalyst (FeZ), three single promoted (KFeZ, CuFeZ, MnFeZ) and four multiple promoted (CuKFeZ, CuMnFeZ, KMnFeZ, CuKMnFeZ) catalysts were synthesized by the incipient to wetness impregnation method. They were characterized by XRD, BET, TPR, TEM and TPD analyses methods and tested for their FT synthesis activities. Promoters had considerable impacts on the compositions and the hydrocarbon distributions of the FT synthesis products. Addition of promoters resulted in an increase of up to 8.5–56% and 20–743% in the synthesis of gasoline and diesel range hydrocarbons, respectively. Consequently, the production of the total liquid fuel (gasoline + diesel) also increased from 48% (base catalyst) to 64–79% (promoted catalysts). The highest gasoline range hydrocarbon production was obtained from MnFeZ and CuKMnFeZ (≈70%) while CuKMnFeZ produced a FT product having the highest total liquid fuel (≈79%).
Selami Demirelli,Sule Karakelleoglu,Fuat Gündog˘du,Muhammed Hakan Tas,Ahmet Kaya,Hakan Duman,Hüsnü Deg˘irmenci,Hikmet Hamur,Ziya Simsek 대한심장학회 2013 Korean Circulation Journal Vol.43 No.7
Background and Objectives: The aim of this study was to investigate the impact of treatment with oral trimetazidine (TMZ) applied before and after percutaneous coronary interventions (PCI) on short-term left ventricular functions and plasma brain natriuretic peptide (BNP) levels in patients with non-ST segment elevation myocardial infarction (NSTEMI) undergoing PCI. Subjects and Methods: The study included 45 patients who were undergoing PCI with the diagnosis of NSTEMI. The patients were ran-domized into two groups. The first group (n=22) of the patients hospitalized with the diagnosis of NSTEMI was given conventional therapy plus 60 mg TMZ just prior to PCI. Treatment with TMZ was continued for one month after the procedure. TMZ treatment was not given to the second group (n=23). Echocardiography images were recorded and plasma BNP levels were measured just prior to the PCI and on the 1st and 30th days after PCI. Results: The myocardial performance index (MPI) was greater in the second group (p=0.02). In the comparison of BNP levels, they signifi-cantly decreased in both of the groups during the 30-day follow-up period (29.0±8 and 50.6±33, p<0.01 respectively). However, decreasing of BNP levels was higher in the group administered with TMZ. The decrease of left ventriclular end-diastolic volume was observed in all groups at 30 days after intervention, but was higher in the group administered with TMZ (p=0.01). Conclusion: Trimetazidine treatment commencing prior to PCI and continued after PCI in patients with NSTEMI provides improvements in MPI, left ventricular end diastolic volume and a decrease in BNP levels.