Sürdürülebilir Kalkınma Amaçları

Yazarlar

  • MakaleAçık Erişim2021Scopus SJRQ1
    Influence of Mg addition and T6 heat treatment on microstructure, mechanical and tribological properties of Al–12Si–3Cu based alloy

    BEDER, M.; ALEMDAG, Y.

    The aim of the present study was to investigate the influence of Mg addition and T6 heat treatment on microstructure, mechanical and tribological properties of the Al–Si–Cu–Mg alloys. In this context, a series of Al–12Si–3Cu–(0.5–2.5)Mg (wt.%) alloys were produced by permanent mould casting, and then subjected to T6 treatment. Their microstructure and mechanical properties were investigated using OM, XRD, SEM, EDS along with hardness, tension, compression and Charpy impact tests. Dry sliding friction and wear properties of the alloys were studied using a ball-on-disk type tester. It was observed that the microstructure of as-cast Al–12Si–3Cu–Mg alloys consisted of α(Al), Si, θ-CuAl2, β-Mg2Si, Q-Al5Mg8Cu2Si6 and π-Al8Mg3FeSi6 phases. T6 heat treatment gave rise to nearly spherodization of eutectic Si particles, formation of finer θ-CuAl2 and β-Mg2Si precipitates and elimination of Chinese script morphology of β-Mg2Si phase. The addition of Mg up to 2.5 wt.% decreased the hardness, tensile and compressive strengths, tensile elongation and impact toughness of the as-cast and T6-treated alloys and increased their friction coefficient and volume loss. T6 treatment, on the other hand, led to a significant increase in mechanical properties and wear resistance of as-cast alloys.

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  • MakaleAçık Erişim2021Scopus SJRQ3
    Statistical behaviours of earthquake occurrences in the Central Anatolian Region of Turkey: region-time-magnitude analyses

    Öztürk, Serkan

    The main objective of this work is to make detailed region-time-magnitude analyses by describ-ing the statistical behaviours of earthquakes in the Central Anatolian Region of Turkey. In this scope, several seismic and tectonic parameters such as Mcomp, b-value, Dc-value, Z-value, recurrence times and annual probabilities were evaluated. For the analyses, a homogeneous catalogue including 10,146 earthquakes with 1.0 ≤ Md ≤ 5.7 between 30 July 1975 and 29 December 2018 was used and spatio-temporal changes of earthquake behaviours were mapped for the beginning of 2019. Earthquake magnitudes varied from 1.9 to 3.0 on average, and hence Mcomp was considered to be 2.6. The b-value was calculated as 1.26 ± 0.07, and this relatively large value indicates that small-magnitude events are dominant. The Dc-value was computed as 1.31 ± 0.03. This small value means that distances between epicentres approach the diameter of the cluster, and seismic activity is more clustered at smaller scales or in larger regions. The spatio-temporal analyses of recurrence times suggest that the Central Anatolian Region has an intermediate/long-term earthquake hazard in comparison to occurrences of strong earthquakes in the short term. Several anomaly regions of a small b-value and a large Z-value were found in and around the Tuzgölü Fault Zone, Central Anatolian Fault Zone, Salanda fault and Niğde fault at the beginning of 2019. Thus, a combination of the regions with a lower b-value, a higher Z-value and also moderate recurrence times may give significant clues for the future possible earthquakes, and detected regions may be thought to be the most likely areas for strong/large events in the Central Anatolian Region.

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  • MakaleYalnız künye2021Scopus SJRQ2
    Assessment of the concentration and environmental impacts of potential hazardous elements in coalfields in Northeastern Turkey

    Saydam Eker, Ç.; Sipahi, F.; Akpınar, I.

    To investigate the impact of potential hazardous element (PHE) contamination on environmental and human health, the coaly shale, coal and shale coal outcrops of four sites, namely Ozyurt, Tarhanas, Kayadibi (Gümüşhane), and Manas (Bayburt), were selected as sampling areas for this study. The samples were analyzed using inductively coupled plasma (ICP) emission spectrometry and inductively coupled plasma-mass spectrometry (ICP-MS) and a Rock–Eval 6 analyzer with a total organic carbon module. The enrichment factor (EF), potential ecological risk index (RI), and potential health risk index (HI) assessment models were used to evaluate the environmental and health risks in the vicinity of the coals. Results indicated that the mean concentrations of PHEs extensively changed and even exceeded the upper continental crust and world average values of low-rank coal concentrations. The assessment of the EF, RI and HI models revealed that the contamination levels of As, Hg, and Cd were higher than those of Pb, Co, Ni, V, and Mo. The evaluation of the EF revealed that the largest and lowest contamination levels of As, Hg, and Cd were observed in Ozyurt (29) and Kayadibi (1.8), Manas (9.6) and Kayadibi (1), and Kayadibi (5.6) and Tarhanas (1.9), respectively. A high-potential ecological risk was present in Ozyurt and Manas, whereas a considerable risk exists in Kayadibi and Tarhanas. The potential health risk values of As for children in Ozyurt, Tarhanas, and Manas and adults in Ozyurt were excessively high. This finding suggested the possibility of transferring the contamination from the coal, shale coal, and coaly shale outcrops

    • SDG 3 · Sağlık ve Kaliteli Yaşam
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  • MakaleYalnız künye2021Scopus SJRQ2
    Optimization of ohmic heating assisted hydrodistillation of cinnamon and bay leaf essential oil

    Tunç, Merve Tuğçe; Koca, İlkay

    In this work, optimum ohmic heating assisted hydrodistillation (OAHD) conditions for extraction of cinnamon (CEO) and bay leaf (BEO) essential oil were determined by response surface methodology (RSM). OAHD were compared with conventional hydrodistillation (HD). Hydrodistillation time (30–120 min), mass of sample (20–40 g) and voltage gradient (7.5–12.5 V/cm), were varied to maximize essential oil (EO) yield and minimize energy consumption. Optimized OAHD conditions were determined as 119.90 min, 8.83 V/cm and 40 g, and 120 min, 8.53 V/cm and 40 g for CEO and BEO, respectively. EO yields of cinnamon and bay leaves at optimum conditions were found 3.98 ± 0.25% and 1.36 ± 0.14%, respectively. Energy consumptions were found 0.42 ± 0.02 and 0.86 ± 0.09 kWh/g EO for CEO and BEO, respectively. EO yield of OAHD was found to be higher when compared with HD methods for both plant materials. Energy consumptions and emitted CO2 values of OAHD method were significantly (p < 0.05) lower than HD methods. Cinnamaldehyde (CEO) and eucalyptol (BEO) contents of essential oils extracted with OAHD were higher when compared with HD methods. Antioxidant activities of essential oils extracted with different methods were not significantly different. CEO and BEO formed inhibition zones against all tested microorganism strains. Practical Applications: Essential oils of cinnamon bark and bay leaf are commonly used for food and pharmaceutical industries and, have important economic value. Conventional hydrodistillation method to extraction essential oils is time consuming, requires more energy and has more CO2 emission rates. Ohmic heating assisted hydrodistillation as a novel technology, is a promising method to extraction of essential oils from different plant materials with lower process times and energy consumption when compared with conventional hydrodistillation. Ohmic heating assisted hydrodistillation method can developed with regard to scale up as a green technology to essential oil production. This work provides a knowledge about the effects of different OAHD process variables on essential oil yield and energy consumption for cinnamon bark and bay leaf essential oils. It is expected that the outcomes of this study will be useful for the designing of large scale ohmic heating assisted hydrodistillation units.

    • SDG 7 · Erişilebilir ve Temiz Enerji
    AtıfScopus24WoS19OpenAlex23
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  • MakaleAçık Erişim2021Scopus SJRQ1
    Effect of cellulose nanofiber-based coating with chitosan and trans-cinnamaldehyde on the microbiological safety and quality of cantaloupe rind and fresh-cut pulp. Part 2: Quality attributes

    Ozturk, Samet; Zhang, Jin; Singh, Rakesh K.; Kong, Fanbin

    The quality characteristics of fruits and vegetables can be protected with coatings. The presented study aimed to evaluate the effect of cellulose nanofiber (CNF) based coatings with chitosan (CHI) and trans-cinnamaldehyde (TC) on the quality attributes, including weight loss, total soluble solid (TSS) content, firmness, and color of whole and fresh-cut cantaloupe during storage at 22 °C and 4 °C, respectively. Results showed that CNF-based coating was effective in protecting whole cantaloupes from firmness reduction and color change in redness/greenness (a*) and yellowness/blueness (b*) during room-temperature storage for up to 11 days. Coating containing only CNF was not able to prevent the quality changes of fresh-cut cantaloupe during the cold storage, but CNF + CHI/CNF + CHI + TC significantly decreased the weight loss, decelerated the firmness increase and maintained the lightness (L*) of fresh-cut cantaloupe for up to 7 days. The incorporation of chitosan (1%, w/w) improved the protection effect of CNF-based coatings against quality changes during storage for both whole and fresh-cut cantaloupes, but TC (1%, w/w) did not show significant enhancement on the protection effects of coatings for most quality attributes. This study indicates that the CNF-based coatings have the potential to maintain quality attributes of whole and fresh-cut fruits during storage and distribution.

    • SDG 2 · Açlığa Son
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  • MakaleAçık Erişim2021Scopus SJRQ1
    An Investigation of the Effect of COVID-19 on OCD in Youth in the Context of Emotional Reactivity, Experiential Avoidance, Depression and Anxiety

    Seçer, İsmail; Ulaş, Sümeyye

    In addition to the serious physical and medical effects on individuals, the COVID-19 pandemic is likely to have short- and long-term psycho-social consequences, especially for young people. Nowadays, with psychological problems becoming more widely recognized in adolescents, it is possible that the fear and anxiety caused by the pandemic will trigger various anxiety disorders, OCD and similar negative outcomes. Considering that psychological qualities such as emotional reactivity and experiential avoidance observed in adolescents may increase the risk of such psycho-social disorders, in this study the relationship between fear of COVID-19 and OCD was investigated in a Turkish sample of 598 adolescents, and the mediating role of emotional reactivity, experiential avoidance and depression-anxiety in this relationship was examined. The data collection was performed online rather than in person because of the COVID-19 threat. A structural equation model was used to determine the direct and indirect predictive effects between variables in data analysis. The results of the study show that the effect of COVID-19 fear on OCD is mediated by emotional reactivity, experiential avoidance and depression-anxiety.

    • SDG 3 · Sağlık ve Kaliteli Yaşam
    AtıfScopus97WoS98OpenAlex142
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  • MakaleAçık Erişim2021
    Estimation of ground types in different districts of Gümüşhane province based on the ambient vibrations H/V measurements

    Öztürk, Serkan; Beker, Yasemin; Sari, Mahmut; Pehlıvan, Levent

    In this study, an attempt was made to estimate the ground types for Torul, Kürtün, Kelkit, Şiran and Köse districts of Gümüşhane, Turkey, by analyzing the predominant frequency and H/V ratio from microtremor data through the single station microtremor H/V ratio of Nakamura technique. For all districts, predominant frequencies show a general distribution between 1.36 and 9.84 Hz, H/V ratios between 1.01 and 9.58. According to these variations, three transient zones can be suggested as i) Z1, stiff rock composed of gravel, sand and other soils mainly consisting of tertiary or older layers with period of 0.1 to 0.2s, ii) Z2, sandy gravel, stiff sandy clay, loam or sandy alluvial deposits whose depths are 5m or greater with period of 0.2 to 0.4s, and iii) Z3, standard grounds other than type Z1, Z2 or Z4 (alluvial deposits whose depths are 5m or greater) with period of 0.4 to 0.8s. These r esults s uggest that p redominant period obtained from predominant frequency shows significant changes based on the soil formation, and H/V ratio highly corresponds to these subsurface properties. Soil-structure interaction can also be evaluated by considering these results and possible resonance risk can be investigated for building resonant frequency in these residential districts in the next. Thus, this type of application and evaluation of microtremor data may provide primary and useful information for other geophysical, geological and geotechnical studies such as planning the seismic resistant infrastructure, detecting the small-scale seismic risks and making a suitable and reliable seismic hazard microzonation in Gümüşhane. Copyright 2021, Yıldız Technical University.

    • SDG 11 · Sürdürülebilir Şehirler ve Topluluklar
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  • MakaleYalnız künye2021Scopus SJRQ4
    Gynecological Cancer Awareness Among Women

    Özcan, Handan; Demir Doğan, Melike

    Purpose: The purpose of this study is to evaluate and determine the gynecological cancer awareness among women aged 20 and over and make recommendations according to the current situation. Method: The study is a quantitative, descriptive, and cross-sectional study. The population of the study was composed of a total of 60.290 women aged over 20 years living in the city center of Gumushane according to TURKSTAT data for 2017. The sample consisted of a total of 382 women determined at 95% confidence interval. Personal information form and Gynecological Cancer Awareness Scale were used to collect the data. Results: The mean age of the women was 39.07 ± 17.84. 48.6% of the participants had knowledge about gynecological cancers, and only 16.2% reached this information from healthcare personnel. It was determined that the women who were working, had an employed husband, had a high level of education, had a husband with high level of education, had no chronic disease, and had knowledge about gynecologic cancers were higher than the others. The awareness of the participants about gynecological cancer decreased as their ages, body mass index, the number of pregnancy and birth increased. The gynecological cancer awareness of the women increased with the increase in marriage age, the age of first sexual intercourse, and the age of first pregnancy. Conclusion: Early diagnosis of gynecological cancers with effective and common screening programs is very important in reducing mortality and morbidity rates. It is recommended to maintain healthy lifestyle behaviors, avoid risky behaviors, screen risky groups and ensure women’s awareness for primary prevention.

    • SDG 3 · Sağlık ve Kaliteli Yaşam
    • SDG 5 · Toplumsal Cinsiyet Eşitliği
    AtıfScopus19WoS20OpenAlex24
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  • MakaleAçık Erişim2021Scopus SJRQ1
    Effect of heat treatment on mechanical and wear properties of Zn–40Al–2Cu–2Si alloy

    SAVAŞKAN, Temel; AZAKLI, Zeki; HEKÌMOĞLU, Ali Paşa

    In order to determine the effect of heat treatment on the mechanical and wear properties of Zn–40Al– 2Cu–2Si alloy, different heat treatments including homogenization followed by air-cooling (H1), homogenization followed by furnace-cooling (H2), stabilization (T5) and quench–aging (T6 and T7) were applied. The effects of these heat treatments on the mechanical and tribological properties of the alloy were studied by metallography and, mechanical and wear tests in comparison with SAE 65 bronze. The wear tests were performed using a block on cylinder type test apparatus. The hardness, tensile strength and compressive strength of the alloy increase by the application of H1 and T6 heat treatments, and all the heat treatments except T6, increase its elongation to fracture. H1, T5 and T6 heat treatments cause a reduction in friction coefficient and wear volume of the alloy. However, this alloy exhibits the lowest friction coefficient and wear volume after T6 heat treatment. Therefore, T6 heat treatment appears to be the best process for the lubricated tribological applications of this alloy at a pressure of 14 MPa. However, Zn–40Al–2Cu–2Si alloy in the as-cast and heat-treated conditions shows lower wear loss or higher wear resistance than the bronze.

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  • MakaleAçık Erişim2021
    The Effects of Economic Recessions on Divorce Rates: A Research on Turkey; [Ekonomik Resesyonların Boşanma Oranları Üzerindeki Etkileri: Türkiye Üzerine Bir Araştırma]

    Koç, Pınar; Kutlar, Aziz

    This study analyses the relationship between short-and long-term relationships between divorce rates and economic recession in Turkey. The asymmetric and time-varying asymmetric causality tests are used to analyse the short-term relationship, the Maki cointegration test is used to analyse the long-term relationship. The dependent variable of the model is the divorce rate. Labour force participation rate of women, unemployment rate, GDP per capita, legal regulations, and economic crises are independent variables. According to the estimation results, unemployment, national income, legal regulations, and economic crises positively affect divorce rates. The time-ric causality test results also indicate a temporary causality relationship between positive income and unemployment shocks.

    • SDG 8 · İnsana Yakışır İş ve Ekonomik Büyüme
    • SDG 16 · Barış, Adalet ve Güçlü Kurumlar
    AtıfScopus2WoS4OpenAlex4TR Dizin3
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  • MakaleYalnız künye2021Scopus SJRQ3
    The role of gender in the government expenditure and unemployment nexus: An investigation at regional level for Turkey

    Çelik, Orkun; Erer, Elif

    We aim to explore the role of gender in the government expenditure and unemployment nexus at regional level for Turkey. For this aim, we use the dataset covering the period 2004-2019 for 26 NUTS-2 regions in Turkey and employ a panel ARDL approach. The obtained empirical findings show that government expenditure and gross domestic product per capita provide overall, female, and male unemployment rates to diminish in the long term, which means the Keynesian approach is valid on the long term. Nevertheless, on the short term, government expenditure induces rises in the male and female unemployment rates. This result indicates the validation of the Abrams Curve Hypotesis in male and female unemployment rates on the short term. Also, inflation rate increases overall and male unemployment rate on the long term, but having significant and positive impact on only female unemployment rate on the short term. All these findings show that gender has a significant role in this nexus. The expected contribution of this study to literature is to investigate the impact of government expenditure on unemployment by gender at regional level for Turkey. We are of opinion that our empirical findings can guide policy makers in active plans fighting unemployment.

  • MakaleYalnız künye2021Scopus SJRQ2
    The effects of freeze-thaw cycles and block size on the use of the Gümüşhane Granitoid (Gümüşhane/Turkey) as building stone

    Dağ, Serhat; Alemdağ, Selçuk; Kaya, Ayberk

    The present study aims to examine the usability of the Gümüşhane Granitoid as a building stone taking into consideration the short-term freeze-thaw cycles and mean block volume. A total of 180 specimens were used in the study prepared from the block samples compiled from 10 different areas in the Gümüşhane (NE Turkey) provincial borders. Mean block volume was calculated about 8 dm3 during the discontinuity studies carried out on the Gümüşhane Granitoid; as a result of which, it was determined that the granitoids are suited for obtaining blocks. The annual freeze-thaw cycle map of Turkey was used for determining the number of freeze-thaw cycles to be applied on the rocks in addition to taking into account the weathering of monzogranites. A total of 25 freeze-thaw cycle tests were applied on the rocks with experimental studies repeated at every 5 cycles. It was determined following the freeze-thaw tests that significant changes have occurred especially in the strength and water absorption parameters of the monzogranites and that they have been affected negatively. This indicates that the monzogranites are not suited for outdoor use as building stone in regions such as the Gümüşhane province and regions with similar climate characteristics, but that they can be used in a lot of regions with more moderate climates. As a building stone, monzogranites can be used either as cobblestone, curbstone, or paving stone subject to their mean block volume. It is considered that the widespread of the Gümüşhane Granitoid may provide a substantial economical income to the country.

    • SDG 11 · Sürdürülebilir Şehirler ve Topluluklar
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  • MakaleAçık Erişim2021
    A determination of the relationship between the symptoms, hospital anxiety and depression levels, and quality of life patients diagnosed with Covid-19

    Sayilan, Samet; Aydin Sayilan, Aylin; Demir Doğan, Melike; Çetinkaya, Emel; Olcayturk, Nuray

    Introduction: The worldwide spread of coronavirus over the last 20 years has resulted in its becoming a major threat to health. The virus is thought to be a zoonotic disease spread by means of direct and contact transmission. The purpose of this study was to investigate the symptoms, anxiety-depression levels, and quality of life of patients with Covid-19. Material and methods: This descriptive, cross-sectional research was conducted in an education and research hospital between August and November 2020. An information form, the Hospital Anxiety and Depression Scale, and the Quality of Life Scale were employed as data collection tools. The study was completed with 103 individuals. Results: The mean age of the patients enrolled in the study was 37.77±10.92 years, and 67% were women. Higher anxiety levels were determined in women compared to men (p=0.001) and in married participants compared to unmarried individuals (p=0.010). Significant negative correlation was determined between anxiety and the Quality of Life Scale sub-parameters of general health, physical health, psychological health, and environment. Positive correlation was found between Covid-19 severity and anxiety, and negative correlation between Covid-19 severity and physical health (p<0.001). Conclusion: Higher anxiety was determined among women and married patients in this study, and quality of life (in the four sub-parameters) decreased as anxiety increased. Physical health decreased, while anxiety increased, with the severity of Covid.

    • SDG 3 · Sağlık ve Kaliteli Yaşam
  • Derleme MakaleAçık Erişim2021Scopus SJRQ1
    Microbulb and plantlet formation of a native bulbous flower, Lilium monodelphum M. Bieb, var. Armenum, through tissue culture propagation

    AZERİ, F.N.; Öztürk, G.

    The plant Lilium monadelphum M. Bieb. var. armenum (Mıscz. Ex Grossh) Davis et Henderson recognized as the caucasian lily grows in the Eastern Black Sea Region and is a perennial bulbous species belonging to the Liliaceae family. Its flowers, bulbs, and volatile oils are used in the perfume industry, as a folk medicine to treat eczema and abscess therapy, and as a tranquilizer among regional people respectively. Hence, it is commonly collected from the wild and could become endangered. In this study, we explored the optimal hormone treatment for efficient and rapid induction and production of this species in tissue culture. Explants taken from bulbs were cultured in Murashige and Skoog medium (MS medium, 1962) and modified with TDZ (thidiazuran) (0.5; 1.0; 2.0; 3.0; 5.0 mg/L), after which adventitious buds used for explants during the second stage were subcultured 4 different media supplemented with different concentrations of PAC (paclobutrazol) (0.1; 0.5; 1.0; 2.0 mg/L) to induce microbulbs formation. Microbulbs were cultured in a rooting medium containing IBA (0.5;1.0 mg/L). The highest bud regeneration was observed in medium containing 3.0 mg/L TDZ, 0.25 mg/L NAA and 0.1 mg/L GA3; the highest microbulb formation was observed in medium containing 2.0 mg/L PAC, 0.2 mg/L NAA, and 0.1 mg/L GA3. Besides, plant development from the microbulb was successful for roots in a medium containing 0.5 mg/I IBA and all of the plantlets obtained in tissue culture survived when transferred to the soil.

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  • MakaleYalnız künye2021Scopus SJRQ3
    The effect of metalation processes on polymer morphology and conductivity properties

    Sarıbıyık, Oğuz Yunus; Gönül, İlyas; Ay, Burak; Karaca, Serkan

    In this work, an insoluble three dimensional (3D) porous polymeric structure and their metal complexes were synthesised by the condensation reactions of meta(m)-phenylenediamine, para(p)-phenylenediamine and glutaraldehyde. The morphological and spectral features of the porous polymeric structures were determined using different analytical and spectroscopic methods, including field emission scanning electron microscopy, four-point probe electrical conductivity, photoluminescence spectroscopy, Fourier-transform infrared spectroscopy, surface area Brunauer–Emmett–Teller and magnetic and thermal behaviours. According to the obtained data, the shape, size and photoluminescence properties of the compounds, especially the conductivity, were clearly changed after the metalation processes.

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  • MakaleYalnız künye2021Scopus SJRQ2
    Determination of Angelica archangelica’s Antioxidant Capacity and Mineral Content

    Topal, Meryem; Ozturk Sarıkaya, S. Beyza; Topal, Fevzi

    The aim of this study was to determine the mineral contents by ICP-MS and the antioxidant capacity of Angelica archangelica plant, which is not well known in the literature. For this purpose, ethyl alcohol extracts of the branches and leaves of the plant; different bioanalytical methods such as reducing capacity by Fe3+−Fe2+ transformation method, Fe3+-TPTZ reducing capacity by FRAP method, Cu2+-Cu+ reducing capacity by CUPRAC method, the ferric ions (Fe2+) chelating activity by using bipyridyl reagent, DPPH (1,1-diphenyl-2-picryl-hydrazyl) free radical, DMPD (N,N-dimethyl-p-phenylenediamine), ABTS (2,2’-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) radical scavenging activities, total antioxidant activity determination according to thiocyanate method, total phenolic and total flavonoid activity were used. As standard, BHT, BHA, α-Tocopherol, Trolox were used. A. archangelica branches and leaves demonstrated 88.13 % and 93.90 % inhibition of linoleic acid emulsion peroxidation at 20 mg mL−1 concentration. Also, it was determined that both leaves and branches of A. archangelica plant were dense with P, Mg, Ca and K minerals with ICP-MS device. It is considered that the results of the manuscript will guide the antioxidant studies, medicine, cosmetics, pharmacology and food sector.

    AtıfScopus15WoS12OpenAlex14
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  • MakaleAçık Erişim2021
    On fourth order accuracy stable difference scheme for a multi-point overdetermined elliptic problem; [Көпнүктелi қайтаанықталған эллипстiк есеп үшiн төртiншi реттi дәлдiктi тұрақтылық айырымдық схемасы туралы]; [Об устойчивой разностной схеме четвертого порядка точности для многоточечной переопределенной эллиптической задачи]

    Ashyralyyev, C.; Akyuz, G.

    In this paper fourth order of accuracy difference scheme for approximate solution of a multi-point elliptic overdetermined problem in a Hilbert space is proposed. The existence and uniqueness of the solution of the difference scheme are obtained by using the functional operator approach. Stability, almost coercive stability, and coercive stability estimates for the solution of difference scheme are established. These theoretical results can be applied to construct a stable highly accurate difference scheme for approximate solution of multipoint overdetermined boundary value problem for multidimensional elliptic partial differential equations.

    AtıfOpenAlex5
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  • MakaleYalnız künye2021Scopus SJRQ2
    Effects of GSM 1800 band radiation on composition, structure and bioactivity of exopolysaccharides produced by yoghurt starter cultures

    Karatas, Seyda Merve; Ekici, Lutfiye; Develi, Ibrahim; Dertli, Enes; Sagdic, Osman

    In this study, the effects of GSM 1800 band radiation on composition, structure and bioactivity of exopolysaccharides (EPSs) produced by Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus were determined. For this, GSM 1800 band radiation was applied to both cultures and characteristics of EPSs extracted from the control groups (K) and the radiation stressed groups (R) were determined. An alteration in the chemical composition of the EPSs was observed and EPS production levels and molecular weights of the EPSs increased following the GSM 1800 band radiation application. Alterations in the functional groups, thermal and morphological characteristics of EPSs following the GSM 1800 band radiation application were confirmed by FTIR, TGA and SEM analysis, respectively. Importantly no alterations in the antioxidant and antibacterial activity of the EPSs were observed following the radiation application. These results suggested the effects of the GSM radiation on final characteristics of EPSs from yogurt starter cultures.

    AtıfScopus8WoS5
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  • MakaleYalnız künye2021Scopus SJRQ2
    Effects of the addition of rose hip on various nutritional and quality properties of ice cream

    Ürkek, Bayram

    In this study, the effects of rose hip (Rosa L.) on the physical, chemical and sensory characteristics, antioxidant activity and mineral contents of ice cream were investigated. Four different proportions (0, 5%, 10% and 15%) of rose hip were used in ice cream production. The sample containing 15% rose hip had the highest antioxidant activity (DPPH and total phenolic content, 28.71 mg sample mg-1 DPPH and 1555 mg GAE g-1 extract, respectively) and vitamin C (246.50 mg 100 g-1) among all ice cream samples. The L* and White Index values of the samples decreased significantly with the increment of rose hip concentration while the a* and b* values increased. The calcium, magnesium, sulfur, potassium, manganese, iron and zinc values increased with the addition of rose hip. Sensory results showed that the ice cream sample containing 15% rose hip had lower score than the control sample in terms of color, appearance, gumming structure, flavor and general acceptability.

    AtıfScopus6WoS3
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  • MakaleAçık Erişim2021Scopus SJRQ4
    Modal control of cantilever beam using a gyrostabilizer

    Çuvalci, Olkan; Ünker, Faruk; Baturalp, Turgut Batuhan; Gülbulak, Utku; Ertas, Atila

    In this paper, an experimental model of a horizontal cantilever beam with a rotating/oscillating attached to the shaker for harmonic excitation at the one end and a gyrostabilizer at the other end is built to verify the equations of the Lagrangian model. The primary focus of the study was to investigate the parameters of excitation amplitude, natural frequency, rotating mass (disk mass), and disk speed of gyro that would minimize the amplitude of the beam to identify these effects. Numerical and experimental results indicate that the angular momentum of the gyrostabilizer is the most effective parameter in the reduction of beam displacement.

    AtıfScopus5WoS3
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