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    Effect of Diatomite Weight Fraction on Morphology, Thermal and Physical Properties of Diatomite Filled High Density Polyethylene Composites
    (Polish Acad Sciences Inst Physics, 2018) Sever, K.; Atagur, M.; Altay, L.; Seki, Y.; Uysalman, T.; Sen, I.; Kaya, N.; Guven, A.; Sarikanat, M.
    High density polyethylene (HDPE) has been used extensively in many sectors of the industry. The main reason for the frequent use of HDPE is its low cost, easy processing, and high performance. These sectors include household and garden products, packaging etc. In order to reduce the production cost of plastic products and to improve plastic's moldability and stability, one or more minerals are usually filled into the thermoplastics. The minerals commonly used as fillers in plastic molding compounds include calcium carbonate, talc, silica, wollastonite, clay, mica, glass beads, and alumina trihydrate. In this paper, diatomite (DA) filled HDPE composites were prepared with gelimat mixer and hot press molding technique. Thermal properties of the composites were studied by thermogravimetric analysis and dynamic mechanical analysis. The mechanical properties of the composites were determined by using universal testing machine. Morphology of the composites was investigated by scanning electron microscopy. With the addition of DA into HDPE, significant change in tensile and flexural strengths of HDPE was not observed. The loss and storage moduli increased with increasing weight fraction of DA.
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    Genotype-phenotype correlation, gonadal malignancy risk, gender preference, and testosterone/dihydrotestosterone ratio in steroid 5-alpha-reductase type 2 deficiency: a multicenter study from Turkey
    (Springer, 2019) Abaci, A.; Catli, G.; Kirbiyik, O.; Sahin, N. M.; Abali, Z. Y.; Unal, E.; Siklar, Z.; Mengen, E.; Ozen, S.; Guran, T.; Kara, C.; Yildiz, M.; Eren, E.; Nalbantoglu, O.; Guven, A.; Cayir, A.; Akbas, E. D.; Kor, Y.; Curek, Y.; Aycan, Z.; Bas, F.; Darcan, S.; Berberoglu, M.
    BackgroundStudies regarding genetic and clinical characteristics, gender preference, and gonadal malignancy rates for steroid 5-alpha-reductase type 2 deficiency (5-RD2) are limited and they were conducted on small number of patients.ObjectiveTo present genotype-phenotype correlation, gonadal malignancy risk, gender preference, and diagnostic sensitivity of serum testosterone/dihydrotestosterone (T/DHT) ratio in patients with 5-RD2.Materials and methodsPatients with variations in the SRD5A2 gene were included in the study. Demographic characteristics, phenotype, gender assignment, hormonal tests, molecular genetic data, and presence of gonadal malignancy were evaluated.ResultsA total of 85 patients were included in the study. Abnormality of the external genitalia was the most dominant phenotype (92.9%). Gender assignment was male in 58.8% and female in 29.4% of the patients, while it was uncertain for 11.8%. Fourteen patients underwent bilateral gonadectomy, and no gonadal malignancy was detected. The most frequent pathogenic variants were p.Ala65Pro (30.6%), p.Leu55Gln (16.5%), and p.Gly196Ser (15.3%). The p.Ala65Pro and p.Leu55Gln showed more undervirilization than the p.Gly196Ser. The diagnostic sensitivity of stimulated T/DHT ratio was higher than baseline serum T/DHT ratio, even in pubertal patients. The cut-off values yielding the best sensitivity for stimulated T/DHT ratio were8.5 for minipuberty,10 for prepuberty, and17 for puberty.ConclusionThere is no significant genotype-phenotype correlation in 5-RD2. Gonadal malignancy risk seems to be low. If genetic analysis is not available at the time of diagnosis, stimulated T/DHT ratio can be useful, especially if different cut-off values are utilized in accordance with the pubertal status.
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    Investigation of androgen receptor (AR) gene mutation spectrum in the turkish patients with disorder of sex development
    (Nature Publishing Group, 2018) Onay, H.; Ozen, S.; Turk, T. Sozen; Darcan, S.; Atik, T.; Anik, A.; Guven, A.
    [No Abstract Available]
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    Linear Low Density Polyethylene Filled with Almond Shells Particles: Mechanical and Thermal Properties
    (Polish Acad Sciences Inst Physics, 2019) Altay, L.; Guven, A.; Atagur, M.; Uysalman, T.; Tantug, G. Sevig; Ozkaya, M.; Sever, K.; Sarikanat, M.; Seki, Y.
    The aim of this study is to investigate mechanical and thermal properties of linear low density polyethylene (LLDPE)-based composite prepared with different almond shells powder (AS) contents. In this paper, AS (5, 10, 20, 30, and 40 wt%) filled LLDPE composites were prepared by compounding polyethylene and AS using a co-rotating twin screw extruder. All specimens for mechanical tests were molded using injection molding. 40 wt% AS filling into LLDPE has led to 100% increase in flexural strength of LLDPE. AS filling into LLDPE decreased the MFI value of LLDPE. AS filling into LLDPE at low weight fractions (5 and 10%) has not affected the un-notched impact strength of LLDPE. Thermal properties of the composite were studied by thermal gravimetric analysis (TGA). From TGA analysis, it is seen that degradation of AS within LLDPE started at about 200 degrees C