Browsing by Publisher "Walter de Gruyter GmbH"

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    Mental health of both child and parents plays a larger role in the health-related quality of life of obese and overweight children
    (Walter de Gruyter GmbH, 1985) Kızılay D.Ö.; Sapmaz Ş.Y.; Şen S.; Özkan Y.; Özyurt B.C.; Ersoy B.
    Aims: A decrease in health-related quality of life (HRQOL) measures among obese (OB) and overweight (OW) children has been shown in several studies, but knowledge about the variables affecting HRQOL impairments is missing. The aim of this study was to evaluate the relationship between HRQOL and sociodemographic characteristics, anthropometric measurements, metabolic parameters, mental symptoms and parental attitudes in a sample of OB/OW children. Methods: Eighty-six OB/OW children, aged between 9 and 17 years, participated in the study. We performed sociodemographic questioning, anthropometric examinations and laboratory evaluations of the participants. HRQOL was assessed using the Pediatric Quality-of-Life Inventory (PedsQL), and levels of anxiety and depressive symptoms were measured using the Screen for Child Anxiety-Related Disorders (SCARED) questionnaire and the Children’s Depression Inventory (CDI), respectively. Parental attitudes were assessed with the Parental Attitude Research Instrument (PARI) questionnaire. Results: A statistically significant relationship was found between total scores of CDI and SCARED answered by children and the total and subscale scores of PedsQL. Scores of total quality of life subscale, physical functionality and emotional functionality subscales were significantly lower in children with a family history of mental illness. No relationship was found between PedsQL subscales, anthropometric and metabolic parameters. Conclusions: Emotional problems and parental psychological distress are important factors in models of HRQOL in the OB/OW pediatric population. © 1985 Walter de Gruyter GmbH. All rights reserved.
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    The dissolution kinetics of tincal in phosphoric acid solutions
    (Walter de Gruyter GmbH, 2007) Abali Y.; Bayca S.U.; Guler A.E.
    In this study, the dissolution kinetics of tincal in phosphoric acid solutions was investigated. The effects of reaction temperature, acid concentration, solid to liquid ratio, particle size and stirring speed were determined in the experiments. The results showed that the dissolution rate increased with increasing acid concentration, reaction temperature, stirring speed and increased with decreasing particle size and solid to liquid ratio. The dissolution rate was found to be based on the first order pseudo homogenous reaction model. The activation energy of the tincal in phosphoric acid solution was determined as 42.28 kJ.mol-1. Copyright © 2007 The Berkeley Electronic Press. All rights reserved.
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    Luminescence dating studies of Yeşilova Hoyuk
    (Walter de Gruyter GmbH, 2012) Ekdal E.; Ege A.; Karali T.; Derin Z.
    Ceramic findings collected from Yeşilova Hoyuk located in Izmir were dated using the thermoluminescence dating technique. The area is of significant archaeological importance since it is the first prehistoric settlement in Izmir. Recent archeological observations suggest that human occupation of the region took place about 8500 years ago comparing to previously determined dates of 5000 years. Three samples collected from the same archaeological layer (Neolithic period) in Yeşilova Hoyuk were dated using the thermoluminescence method. Archaeological doses (AD) were obtained by single aliquot regenerative dose method (SAR) for thermoluminescence (TL) using coarse grain quartz minerals extracted from samples. Thick and thin Al2O3:C thermoluminescence dosimeters (TLD) were used to determine the annual dose rate. The archaeological doses were found to vary from 25.91±0.78 to 26.82±0.68 Gy, and the annual doses were found to be between 3.34±0.24 and 3.47±0.24 mGy/a. The ages obtained for the samples were determined to be 6000±830 BC, 5740±670 BC and 5460±740 years for samples ND1, ND2 and ND3, respectively, which supports the prediction of archeologist that the sampling layer dates from the Neolithic period. © 2012 Silesian University of Technology, Gliwice, Poland 2012.
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    Preliminary findings of α-actinin-3 gene distribution in elite Turkish wind surfers
    (Walter de Gruyter GmbH, 2013) Ulucan K.; Göle S.; Altindas N.; Güney A.I.
    A common polymorphism in the α-actinin-3 (ACTN3 R577X) gene represents one of the most widely examined variations in terms of performance and genetic predisposition to certain sports. The aim of the present study was to examine the ACTN3 R577X polymorphism in elite Turkish wind surfers. The genotyping procedure was carried out by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Five male and three female wind surfers, eight elite wind surfers in total, were enrolled in the study. Five of the surfers had RX, two had XX and one had RR genotypes. Previous findings indicated that the X allele was the endurance allele. Our findings were in agreement with the previous reports. Seven of our subjects had at least one copy of the X allele that was considered to have a tendency to prolong endurance. Our preliminary results must be supported with further studies in greater numbers of subjects to clarify the effect of gene polymorphism.
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    A multicenter nationwide reference intervals study for common biochemical analytes in Turkey using Abbott analyzers
    (Walter de Gruyter GmbH, 2014) Ozarda Y.; Ichihara K.; Aslan D.; Aybek H.; Ari Z.; Taneli F.; Coker C.; Akan P.; Sisman A.R.; Bahceci O.; Sezgin N.; Demir M.; Yucel G.; Akbas H.; Ozdem S.; Polat G.; Erbagci A.B.; Orkmez M.; Mete N.; Evliyaoglu O.; Kiyici A.; Vatansev H.; Ozturk B.; Yucel D.; Kayaalp D.; Dogan K.; Pinar A.; Gurbilek M.; Cetinkaya C.D.; Akin O.; Serdar M.; Kurt I.; Erdinc S.; Kadicesme O.; Ilhan N.; Atali D.S.; Bakan E.; Polat H.; Noyan T.; Can M.; Bedir A.; Okuyucu A.; Deger O.; Agac S.; Ademoglu E.; Kaya A.; Nogay T.; Eren N.; Dirican M.; Tuncer G.; Aykus M.; Gunes Y.; Ozmen S.U.; Kawano R.; Tezcan S.; Demirpence O.; Degirmen E.
    Background: A nationwide multicenter study was organized to establish reference intervals (RIs) in the Turkish population for 25 commonly tested biochemical analytes and to explore sources of variation in reference values, including regionality. Methods: Blood samples were collected nationwide in 28 laboratories from the seven regions (≥400 samples/region, 3066 in all). The sera were collectively analyzed in Uludag University in Bursa using Abbott reagents and analyzer. Reference materials were used for standardization of test results. After secondary exclusion using the latent abnormal values exclusion method, RIs were derived by a parametric method employing the modified Box-Cox formula and compared with the RIs by the non-parametric method. Three-level nested ANOVA was used to evaluate variations among sexes, ages and regions. Associations between test results and age, body mass index (BMI) and region were determined by multiple regression analysis (MRA). Results: By ANOVA, differences of reference values among seven regions were significant in none of the 25 analytes. Significant sex-related and age-related differences were observed for 10 and seven analytes, respectively. MRA revealed BMI-related changes in results for uric acid, glucose, triglycerides, high-density lipoprotein (HDL)-cholesterol, alanine aminotransferase, and γ-glutamyltransferase. Their RIs were thus derived by applying stricter criteria excluding individuals with BMI >28 kg/m2. Ranges of RIs by non-parametric method were wider than those by parametric method especially for those analytes affected by BMI. Conclusions: With the lack of regional differences and the well-standardized status of test results, the RIs derived from this nationwide study can be used for the entire Turkish population. © by De Gruyter 2014.
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    Precession of a planet with the multiple scales lindstedt-poincare technique
    (Walter de Gruyter GmbH, 2015) Pakdemirli M.
    The recently developed multiple scales Lindstedt- Poincare (MSLP) technique is successfully applied to a mathematical model of planet motion. The equation is originally developed to precisely understand the orbital motion of the planet Mercury around the Sun and the precession of the orbit due to the relativistic effects. The quadratic nonlinear equation is solved by the classical Lindstedt-Poincare method (LP) and then by the newly developed multiple scales Lindstedt-Poincare method (MSLP). Both approximate solutions are contrasted with the numerical simulations. When the relativistic effects are small, all three solutions coincide with each other. When the perturbation effects are increased, the MSLP solutions agree better with the numerical solutions than the LP solutions. The precession of the perihelion of the planet is calculated and compared for the approximate solutions.
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    First report of the red alga Gayliella fimbriata in the Mediterranean Sea
    (Walter de Gruyter GmbH, 2015) Taşkln E.; Çaklr M.; Wynne M.J.
    The red alga Gayliella fimbriata (Ceramiaceae, Rhodophyta) is reported for the first time from the Mediterranean Sea. This species was collected growing as an epiphyte on Laurencia obtusa in the sublittoral zone at Antalya (Mediterranean coast of Turkey). Gayliella fimbriata is characterized by its protruding clavate gland cells. Features to distinguish the four Turkish species of Gayliella from one another are provided. © 2015 by De Gruyter 2015.
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    Parallel Plate Flow of a Third-Grade Fluid and a Newtonian Fluid with Variable Viscosity
    (Walter de Gruyter GmbH, 2016) Ylldlz V.; Pakdemirli M.; Aksoy Y.
    Steady-state parallel plate flow of a third-grade fluid and a Newtonian fluid with temperature-dependent viscosity is considered. Approximate analytical solutions are constructed using the newly developed perturbation-iteration algorithms. Two different perturbation-iteration algorithms are used. The velocity and temperature profiles obtained by the iteration algorithms are contrasted with the numerical solutions as well as with the regular perturbation solutions. It is found that the perturbation-iteration solutions converge better to the numerical solutions than the regular perturbation solutions, in particular when the validity criteria of the regular perturbation solution are not satisfied. The new analytical approach produces promising results in solving complex fluid problems. © 2016 by De Gruyter.
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    Free and Forced Vibrations of the Strongly Nonlinear Cubic-Quintic Duffing Oscillators
    (Walter de Gruyter GmbH, 2017) Fatih Karahan M.M.; Pakdemirli M.
    Strongly nonlinear cubic-quintic Duffing oscillatoris considered. Approximate solutions are derived using the multiple scales Lindstedt Poincare method (MSLP), a relatively new method developed for strongly nonlinear oscillators. The free undamped oscillator is considered first. Approximate analytical solutions of the MSLP are contrasted with the classical multiple scales (MS) method and numerical simulations. It is found that contrary to the classical MS method, the MSLP can provide acceptable solutions for the case of strong nonlinearities. Next, the forced and damped case is treated. Frequency response curves of both the MS and MSLP methods are obtained and contrasted with the numerical solutions. The MSLP method and numerical simulations are in good agreement while there are discrepancies between the MS and numerical solutions. © 2017 Walter de Gruyter GmbH, Berlin/Boston.
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    The mechanical behaviour of adhesively bonded composite joints under repeated axial impacts at different temperatures
    (Walter de Gruyter GmbH, 2017) Kemiklioglu U.; Sayman O.; Soykok I.F.; Akderya T.; Dere R.
    In this study, the failure strength of single-lap adhesively bonded joints was investigated. The glass fibre epoxy composites used as adherends were manufactured by using a vacuum-assisted resin infusion method. These composites were bonded with a commercial material of epoxy-adhesive DP-460, which can be cured easily at room temperature. The specimens were built by bonding, and then repeated axial impact loads having various energy levels (0, 5, 10, 15, and 20 J) were implemented to the single-lap adhesively bonded composite joints at different temperatures (-20°C, 0°C, 20°C, 40°C, and 60°C). Subsequently, the specimens were exposed to static tensile loading at the same temperatures as those applied during the primary impacts. The variation in failure loads due to the effects of repeated axial impact loadings at different temperatures were investigated. Generally, the increase of impact energy level from 0 to 20 J leads to a gradual decrease in failure loads at all temperature levels except for the specific value of 40°C. © 2017 Walter de Gruyter GmbH, Berlin/Boston.
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    Approximate solutions for the nonlinear third-order ordinary differential equations
    (Walter de Gruyter GmbH, 2017) Karahan M.M.F.
    A new perturbation method, multiple scales Lindstedt-Poincare (MSLP) is applied to jerk equations with cubic nonlinearities. Three different jerk equations are investigated. Approximate analytical solutions and periods are obtained using MSLP method. Both approximate analytical solutions and periods are contrasted with numerical and exact results. For the case of strong nonlinearities, obtained results are in good agreement with numerical and exact ones. © 2017 Walter de Gruyter GmbH, Berlin/Boston 2017.
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    First report, based on morpho-Anatomical data, of the green alga Pseudocodium okinawense (Bryopsidales, Chlorophyta) in the Mediterranean Sea
    (Walter de Gruyter GmbH, 2018) Taşkln E.; Wynne M.J.; Baklr N.
    The green alga Pseudocodium okinawense is reported for the first time from the Mediterranean Sea. The collection of this species from a 54-m depth on a sandy-mud bottom on August 2017 near Kalkan, Turkey, also represents the first report of the genus Pseudocodium from the Mediterranean. The species was previously reported from southern Japan (type locality, Okinawa), Indonesia, New Caledonia and Papua New Guinea. Oil tankers and the several permanent/semi-permanent man-made structures are the likely vectors of introduction. © 2018 Walter de Gruyter GmbH, Berlin/Boston 2018.
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    Cord blood nucleated red blood cell level: Is it a predictive marker for neonatal jaundice?
    (Walter de Gruyter GmbH, 2018) Orhon A.; Topal H.; Hakan N.; Ozer E.A.
    The aim of this study was to evaluate if the cord blood nucleated red blood cell (nRBC) levels can predict the development of hyperbilirubinemia in healthy neonates. All healthy newborn infants born after 35 or more weeks of gestation at our hospital between January 2016 and April 2017 were included. The levels of nRBC were counted in umbilical cord blood samples. Neonates were grouped into two study groups based on the presence or absence of neonatal jaundice. The study included overall 149 eligible newborn infants. The levels of nRBC and absolute nRBC count showed statistically significant differences between newborns with or without jaundice (p=0.01 and 0.02, respectively). We suggest that increased nRBC counts in cord blood may be a predictive marker for hyperbilirubinemia in healthy newborn infants. © 2018 2018 Walter de Gruyter GmbH, Berlin/Boston.
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    Diagnostic value of perinatal autopsies: Analysis of 486 cases
    (Walter de Gruyter GmbH, 2018) Neşe N.; Bülbül Y.
    Aim: Autopsy is a beneficial procedure to determine the cause of death and the frequency of anomalies in perinatal losses. Even in the event of an autopsy not providing any additional information, completion of the procedure confirming the clinical diagnoses gives reassurance to both clinicians and parents. Here we present a 15-year archival study based on findings of perinatal autopsies. Design and methods: Four hundred and eighty-six cases from our archive were reviewed and according to the findings they were divided into three subcategories; (1) miscarriages (MCF); (2) fetuses terminated (FTA) for vital anomalies detected by prenatal ultrasonography; (3) premature or term newborns died within first month of life (neonates: NN). Autopsies were documented and classified according to week/age of cases, anomalies and causes of abortion or death. Results: Two hundred and twenty-six of 486 cases (46.5%) were in MCF group while 227 (46.7%) and 33 (6.8%) were of them in FTA and NN groups, respectively. In FTA group, the most frequent anomaly detected was neural tube defects. In NN group, prematurity related complications were the most common cause of death. The autopsy process was found valuable in 39.7% of all cases. Conclusions: We suggest that autopsy procedure is diagnostically valuable even in situations when there is USG findings that are confirming FTAs or there is no important major fetal or placental anomaly detected in MCFs. © 2018 Walter de Gruyter GmbH, Berlin/Boston.
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    Investigation of the dual cascade algorithm in the diagnosis of antinuclear antibodies
    (Walter de Gruyter GmbH, 2019) Ecemiş T.; Faraşat V.T.; Doğan Y.; Şener A.G.; Ece G.T.; Dündar P.E.; Şanlıdağ T.
    Background: The dual cascade algorithm which involves screening and confirmation of antinuclear antibodies (ANAs) by further reflex testing is widely used in the detection of ANAs. We aimed to investigate this algorithm which is commonly used in many laboratories. Methods: A total of 475 sera obtained from patients with a clinical suspicion of systemic autoimmune rheumatic diseases (SARDs) upon which three expert assessors agreed for interpretation in the indirect immunofluorescence (IIF) test were determined and tested by the line immunoassay (LIA) containing 16 antigens. The results of the tests were statistically compared and evaluated. Results: In 141 of the sera (29.7%), there was an agreement between ANA-IIF(+) and LIA(+) results. The overall agreement rate between the two tests for positivity and negativity only was 85.5% with a Cohen’s κ coefficient of 0.69. In 118 of these 141 sera (83.7%), pattern and associated ANA agreement was detected with an overall agreement rate of 80.6% and a Cohen’s κ coefficient of 0.57. The highest agreement between the pattern and associated ANAs was seen in centromere, dense fine speckled (DFS) and cytoplasmic reticular patterns. In these patterns, the rate of anti-centromere-associated protein B (CENP-B), anti-DFS and anti-antimitochondrial antibody M2 (anti-AMA-M2) antibodies were 93.4%, 92.3% and 66.7%, respectively. Conclusions: We found an overall moderate agreement between IIF screening and LIA confirmation tests. However, the level of agreement varies according to the pattern type. The discrepancy in agreement rates may cause false reflex test requests. Our results highlight the need for collaboration between clinical and laboratory professionals in selected cases instead of the reflex testing approach. © 2019 Walter de Gruyter GmbH. All rights reserved.
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    99mTc(I) carbonyl-radiolabeled lipid based drug carriers for temozolomide delivery and bioevaluation by in vitro and in vivo
    (Walter de Gruyter GmbH, 2019) Arı K.; Uçar E.; İçhedef Ç.; Kılçar A.Y.; Medine E.İ.; Parlak Y.; Bilgin B.E.S.; Aydın B.; Gümüşer F.G.; Teksöz S.
    In preclinical research radiolabeled nanoparticles have been attracting interest as a new class of imaging probes. Assuming good stability of solid lipid nanoparticles (SLNs) under physiological conditions, radiolabeled SLNs can be used for imaging and measuring uptake in target tissue. Present study was performed to evaluate biological behavior of temozolomide (TMZ) loaded solid lipid nanoparticles (SLN-TMZ) in vivo and in vitro. Lipid nanoparticles were prepared by emulsification and low-temperature solidification method. ζ potential, morphology and particle size of nanoparticles were determined. Biological behavior of 99mTc(CO)3+ radiolabeled SLN-TMZ were investigated in vitro on U87/Daoy cell lines and in vivo on female Wistar Albino rats. Obtained results of in vitro incorporation, in vivo biodistribution and gamma imaging studies on radiolabeled SLN-TMZ show that the radiolabeled solid lipid nanoparticles could have potential as a drug delivery system for TMZ. © 2019 Walter de Gruyter GmbH. All rights reserved.
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    Mechanical properties of Al-Cu/B4C and Al-Mg/B4C metal matrix composites
    (Walter de Gruyter GmbH, 2021) Ayvaz M.; Cetinel H.
    AMTo be able to successfully produce ceramic-reinforced aluminum matrix composites by using the powder metallurgy method, the wetting of ceramic reinforcements should be increased. In addition, the negative effects of the oxide layer of the aluminum matrix on sinterability should be minimized. In order to break the oxide layer, the deoxidation property of Mg can be used. Furthermore, by creating a liquid phase, both wettability and sinterability can be improved. In this study, the effects of Mg and Cu alloy elements and sintering phase on the wettability, sinterability, and mechanical properties of Al/B4C composites were investigated.For this purpose, various amounts (5, 10, 20, and 30 wt.-%) of B4C reinforced Al5Cu and Al5Mg matrix composites were produced by the powder metallurgy method. After pressing under 400 MPa pressure, composite samples were sintered for 4 hours. The sintering was carried out in two different groups as solid phase sintering at 560 °C and liquid phase sintering at 610 °C. Despite the deoxidation effect of Mg in Al5Mg matrix composites, higher mechanical properties were determined in Al5Cu composites which were sintered in liquid phase because wettability increased. The highest mechanical properties were obtained in the 20 wt.-% B4C reinforced Al5Cu sample sintered in liquid phase. © 2021 Walter de Gruyter GmbH, Berlin/Boston, Germany.
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    The effect of SiC content on microstructural and tribological properties of sintered B4C and SiC reinforced Al-Cu-Mg-Si matrix hybrid composites
    (Walter de Gruyter GmbH, 2022) Gezici L.U.; Özer E.; Sarpkaya I.; Çavdar U.
    In this study, B4C and SiC hybrid reinforced Al-Cu-Mg-Si alloy Matrix composites were fabricated using a microwave sintering technique at a sintering temperature of 550 °C for 60 min. In the produced hybrid composites, while the B4C ratio was kept constant (3 wt%), SiC was used in four different amounts (3, 6, 9, and 12 wt%). In these produced hybrid composites, as a result of microwave sintering, thanks to the high microwave absorption of SiC, the porosities closed at a rate of 36.65-40.90%. In 3, 6, 9, and 12 wt% SiC reinforced composites, the microhardness of 100.1, 106.8, 114.4, and 117.2 HV0.05 were achieved, respectively. Due to agglomeration increasing with SiC reinforcement rate, delamination wears increased in 12 wt% SiC reinforced hybrid composite. As a result, the lowest specific wear rate was measured as 0.3374 × 10-3 mm3·(Nm)-1 in the 3 wt% B4C+9 wt% SiC reinforced sample. © 2022 Walter de Gruyter GmbH, Berlin/Boston.
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    Surface roughness prediction of wire electric discharge machining (WEDM)-machined AZ91D magnesium alloy using multilayer perceptron, ensemble neural network, and evolving product-unit neural network
    (Walter de Gruyter GmbH, 2022) Gurgenc T.; Altay O.
    Magnesium (Mg) alloy parts have become very interesting in industries due to their lightness and high specific strengths. The production of Mg alloys by conventional manufacturing methods is difficult due to their high affinity for oxygen, low melting points, and flammable properties. These problems can be solved using nontraditional methods such as wire electric discharge machining (WEDM). The parts with a quality surface have better properties such as fatigue, wear, and corrosion resistance. Determining the surface roughness (SR) by analytical and experimental methods is very difficult, time-consuming, and costly. These disadvantages can be eliminated by predicting the SR with artificial intelligence methods. In this study, AZ91D was cut with WEDM in different voltage (V), pulse-on-time (μs), pulse-off-time (μs), and wire speed (mm s-1) parameters. The SR was measured using a profilometer, and a total of 81 data were obtained. Multilayer perceptron, ensemble neural network and optimization-based evolving product-unit neural network (EPUNN) were used to predict the SR. It was observed that the EPUNN method performed better than the other two methods. The use of this model in industries producing Mg alloys with WEDM expected to provide advantages such as time, material, and cost. © 2022 Walter de Gruyter GmbH, Berlin/Boston.
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    A micromechanical approach to elastic modulus of long-term aged chicken feather fibre/poly(lactic acid) biocomposites
    (Walter de Gruyter GmbH, 2022) Akderya T.; Ozmen U.; Baba B.O.
    The modulus of elasticity is a critical parameter for the performance design and analysis of biofibre-based biocomposite materials. As a result of criteria such as internal heterogeneity, the random distribution of fibres and the success of interfacial adhesion between the fibre and the matrix, it becomes difficult to predict the modulus of elasticity in practical ways. Therefore, one of the aims of this study is to determine the modulus of elasticity of biocomposite material reinforced with discontinuous and random fibres by means of micromechanical models and experimentally. In addition, it is also aimed to reveal which micromechanical model can be used reliably in predicting the modulus of elasticity of both aged and non-aged biocomposite materials due to the relationship between the analytical and experimental results. In order to achieve these objectives, initially, chicken feather fibre/poly (lactic acid) biocomposite specimens having 2, 5 and 10 % chicken feather fibre mass fractions were mixed and manufactured by extruding, and subsequently, tensile test specimens according to the appropriate standard were formed by the injection-moulding method. An agreement between the moduli of elasticity obtained from 6 micromechanical models and experimentally from the slope of the stress-strain curves resulting from tensile tests was determined. © 2022 Walter de Gruyter GmbH, Berlin/Boston.