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- MakaleYalnız künye2022Scopus SJRQ3EFFECTS OF USING STYRENE-ISOPRENE-STYRENE AND CRUMB RUBBER ON RUTTING POTENTIAL AND AGING PROPERTIES OF BITUMEN
Kök, Baha Vural; Yalçin, Beyza Furtana; Yilmaz, Mehmet; Yalçin, Erkut
The crumb rubber (CR) obtained from waste vehicle tires is gaining attention from the researchers because of its contribution to performance besides having low cost and environmental-friendly characteristic. In this study the effects of using styrene-isoprene-styrene (SIS) together with CR on rutting and aging properties of binders were evaluated by dynamic shear rheometer, softening point and viscosity tests. B 160/220 (PG 58) pure bitumen was modified in 13 different combinations with different contents of additives. The combined use of SIS and CR was compared with the high rate of SIS and CR modifications individually. It was determined that the combined use of 2% SIS and 7% CR by weight of bitumen provides an economical and superior performance that cannot be achieved with individual SIS or CR modifications. The binary binders were able to preserve their elastic properties after aging better than the individual SIS and CR modifications.
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İncele - MakaleAçık Erişim2021Scopus SJRQ2Effects of Aging on Magnetic and Thermal Characteristics of NiMnCoSn Magnetic Shape Memory Alloys
Kök, Mediha; Aydoğdu, Kumruya; Kanca, M. Sait; Qader, Ibrahim Nazem; Öner, Ecem; Coşkun, Meltem
Heusler shape memory alloys are important for many applications due to their typical magnetic and shape memory behaviors. In this study, a Ni50Mn36Sn12Co2 (at.%) alloy was manufactured by arc-melting technique, then the ingot cooled to ambient temperature in the natural atmosphere. Three different temperatures, including 500 °C (773 K), 700 °C (973 K), and 900 °C (1173 K), was selected for aging the samples cut from the main ingot. The impact of aging on the crystalline; microstructure; caloric; and magnetic properties of the alloys were investigated through x-ray diffraction (XRD); scanning electron microscope; differential scanning calorimetric (DSC), differential thermal analysis, and thermal gravimetric (TG); and physical property measuring system was investigated, respectively. The aging in different temperatures led to the shift DSC curve, such that the martensitic phase transformation temperatures of the sample aged at 773 K increased, however, the transformation at 973 and 1173 K decreased compared to the as-casted alloy. The different phase transformation behavior showed that the alloy aged at 773 K has the maximum elastic energy, enthalpy and entropy change compared to the reset of samples, on the other hand, its crystallite sized obtained from XRD analysis comparably diminished. Besides, the TG analysis revealed that the mass gain almost occurs at a temperature above 773 K, therefore the magnetization of the alloys aged at 973 and 1173 K decreased due to a thin oxide layer formed on the surface of the alloys.
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İncele - MakaleAçık Erişim2020Scopus SJRQ1Performance and Aging Characteristics of Hot Mixture Asphalt with Crumb Rubber and Warm Mix Asphalt Additives
Akpolat, Mustafa; Kök, Baha Vural; Yilmaz, Mehmet
In this study, the mixes prepared using crumb rubber (CR) and binders with warm mix additives were aged through various aging methods (1, 2, 3, and 4 weeks at 60 degrees C in the laboratory; 2, 4, 6, 8, 10, and 12 months under the environmental conditions; and AASHTO R30) and examined in terms of performance and aging index. The indirect tensile strength (ITS), indirect tensile stiffness modulus (ITSM), and fatigue tests were applied to the pure and the CR,CR+Sasobit, andCR+Evothermmodified aged and nonaged mixes, and the aging indexes were determined according to the results obtained. According to the test results,CR+Sasobitwas found to be the best mix in terms of mechanical properties. Using the warm asphalt additives in the CR modification was determined to decrease the aging indexes and retarded the aging. Also determined was that a high correlation exists between the aging at 60 degrees C in the laboratory and the aging under the environmental conditions. Based on the fatigue test results, AASHTO R30 short-term aging (4 h at 135 degrees C) was determined to cause structural deterioration in the mixes and yielded low load repetition relative to the pure mixes. Therefore, using this method for the short-term aging of the CR modified mixes would not be appropriate. When the tests applied were evaluated in terms of the aging indexes, the fatigue test was found to be the most sensitive method for detecting aging in the pure mixes and mixes with additives. (C) 2020 American Society of Civil Engineers.
AtıfWoS17OpenAlex15İncele - MakaleYalnız künye2012Scopus SJRQ1Effectiveness of a Multistimulant Home-Based Program on Cognitive Function of Older Adults
Karatay, Gulnaz; Akkus, Yeliz
The purpose of this study was to test the effects of a multistimulant home-based program on cognitive function among older adults. This study was conducted in northeastern Turkey between March and June 2010. It was planned as an experimental versus control two-group design and carried out on 96 (intervention group = 48, control group = 48) participants. The intervention and control groups were similar regarding sex, education, partner status, and continuous drug use. Data were collected with a Standardized Mini Mental Test, the Geriatric Depression Scale (GDS), and the Beck Anxiety Scale. Each senior received a total of 10 home visits on a once-per-week basis. Results for the intervention group showed that the Mini Mental State Test scores of the participants had statistically increased, and the Beck Anxiety and the GDS scores showed a decrease. The study found an association between the multistimulant home-based intervention program and cognitive function.
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