Hızlı prototipleme yönteminde proses parametrelerinin ürün mekanik özelliklerine etkisinin tespiti

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Anahtar kelimeler: Hızlı prototipleme, eklemeli imalat yöntemleri, 3d yazıcı, mekanik özellikler Bu çalışmada, hızlı prototipleme yöntemlerinden biri olan katmanlı üretim yöntemi ile üretilen parçalarda proses parametrelerinin, cisim mekanik özelliklerine etkisinin incelenmesi amaçlanmaktadır. Bu kapsamda sıklıkla kullanılan mekanik testlerden çekme testi ve üç nokta eğme testi kullanılarak proses parametrelerinin etkisi incelenmiştir. Malzeme olarak termoplastik malzemelerden olan ABS-P430 malzemesi kullanılmıştır. Proses parametresi olarak ise dokuma yoğunluğu ve dokuma açısı parametreleri değişkenleri tercih edilmiştir. Sonrasında, üretilen numunelere çekme ve eğme numuneleri için mekanik testler yapılmış, farklı üretim parametrelerinin mekanik özellikler üzerindeki etkisi incelenmiştir. Üretim parametreleri, 3d baskı cihazının dilimleme arayüzüyle tayin edilmiş olup, boşluksuz, yüksek yoğunluklu ve düşük yoğunluklu olmak üzere üç farklı dilimleme modeli için 00, 300, 450 ve 750 dokuma açılarında üretim yapılmıştır. Elde edilen sonuçlara göre, hammadde aynı olmasına karşın, dilimleme modelinin parçanın mekanik özellikleri üzerinde etkisi olduğu, düşük yoğunluklu dilimleme modeli ile üretilen parçalarda çekme mukavemetinin daha düşük olduğu, ancak eğme durumunda ise düşük yoğunluklu parçaların daha esnek olduğu tespit edilmiştir. Dilimleme açısındaki değişimin, parçanın mekanik özellikleri üzerindeki etkisi tespit edilmiştir. Aynı dilimleme modelinde farklı dokuma açılarıyla üretilen parçalardan 00 ve 450 dokuma açılarıyla üretilen parçaların, hammadde mekanik özelliklerine daha yakın sonuç verdiği, diğer dokuma açılarında üretilen parçaların daha düşük mekanik özellikler gösterdiği tespit edilmiştir. Yapılan çalışma sonucunda hızlı prototipleme yöntemiyle üretilecek parçalarda dilimleme modelinin seçiminin, parçanın kullanım alanına göre tespit edilmesi gerektiği sonucuna varılmıştır.Keywords: Rapid prototyping, additive manufacturing methods, 3d printer, mechanical properties. In this study, mechanical tests for tensile and bending specimens manufactured with 3d printer, one of the methods of rapid prototyping, the effects of different production parameters on mechanical properties were investigated. Production parameters are determined by the slicing interface of the 3D printing machine's device, for three different slicing models with Solid, Sparse High Density, Sparse Low Density, the production was carried out at 00, 300, 450 and 750 weaving angles. According to the results, although the raw material is the same, the slicing model has an effect on the mechanical properties of the part, the tensile strength of the parts produced by the low density slicing model is lower, however, the bending strength of the low density parts was found to be more flexible. The effect of the slicing angle on the mechanical properties of the part was determined. In the same slicing model, the pieces produced with different weaving angles and the pieces produced with 00 and 450 product angles give closer results to the raw material's mechanical properties, it was determined that the parts produced in other product angles exhibit lower characteristics. As a result of the study, it was concluded that the selection of the slicing model in the parts to be produced by rapid prototyping method should be determined according to the usage area of the piece

The static and free vibration analyses of axially functionally graded elliptical beams via mixed FEM

The objective of this study is to investigate the behavior of the static and free vibration analyses of axially functionally graded elliptical planar curved beams using a mixed finite element method (MFEM) based on the Timoshenko beam theory. A two-noded curved mixed finite element has 12 field variables at each node. These variables denote three displacements, three cross-sectional rotations, three forces, two bending moments, and torque, respectively. The functionally graded material is composed of ceramic-particle material and metal-matrix material. The volume fraction of ceramic and metal materials varies along the beam axis. The effective material properties (modulus of elasticity, Poisson's ratio, and density) of the functionally graded material are determined according to the rule of mixture. It is aimed in the benchmark examples to present the influence of ceramic-particle material and non-homogeneity index of material gradation, the minimum radius of the elliptical beam, and boundary condition to the results of static and free vibration analysis in detail

The effects of milled Tribulus terrestris, Avena sativa, and white ginseng powder on total cholesterol, free testosterone levels and testicular tissue in rats fed a high-cholesterol diet

This study examines the effects of milled Tribulus terrestris (TT), Avena sativa (AS), white ginseng (WG) and triple-combination (TC) powders on sexual dysfunction parameters - such as serum total cholesterol, free testosterone levels and histopathological changes in testicular tissue - in rats fed a high-cholesterol diet. The study's animal matenal consisted of 42 male Wistar albino rats weighing 200-210 g divided into six groups. Group I was fed normal pellet feed, while the remaining groups were fed pellet feed containing 2% cholesterol. Group III, IV, V, and VI also received 0.6 g/kg/day of TT, 0.3 g/kg/day of AS, 0.2 g/kg/day of WG and 0.55 g/kg/day of TC (7.5% TT, 3.75% AS, 2.5% WG), respectively. After 90 days, the rats were sacrificed and blood and testicular tissue samples obtained. Serum total cholesterol and free testosterone levels were measured, and the Johnsen testicular biopsy score (JTBS) was calculated by a histopathological examination of testicular tissue samples. The high-cholesterol diet in Group II significantly caused increase in total cholesterol level and decrease in JTBS as compared to Group I. Although the groups' free testosterone levels were not statistically significant, WG and TC significantly prevented total cholesterol increase. TC significantly increased the JTBS compared to TT, AS and WG alone. Thus, it was concluded that TC might be particularly efficient for improving male sexual dysfunction

Interleukins As a Marker of Inflammation in Diabetic Foot Syndrome and Type 2 Diabetes Mellitus

Conclusion: According to our results, IL-12 P70, IL-17 and IL-18 can be used as biomarkers for diabetic foot. Further studies arc needed to show the role of IL-12 P70, IL-17 and IL-18 levels as a biomarker in chronic inflammatory diseases

The effect of irritable bowel syndrome on carotid intima-media thickness, pulse wave velocity, and heart rate variability

Objective: Irritable bowel syndrome (IBS), a subgroup of functional somatic disorders, may be associated with autonomic dysfunction (AD). Heart rate variability (HRV), a measure of autonomic dysfunction, may predict survival. The aim of this study was to investigate the effect of IBS on HRV parameters, carotid intima-media thickness (CIMT) and carotid-femoral pulse wave velocity (cf-PWV) as surrogates of AD, subclinical atherosclerosis and arterial stiffness, respectively. Methods: Our study was cross-sectional and observational. Thirty consecutive patients with IBS and 30 control participants underwent 24-hour Holter monitoring, cf-PWV assessment and CIMT measurement. The diagnosis of IBS was based on Rome III criteria. There were 24 patients with IBS-Constipation (80%), 4 patients with IBS-Diarrhea (13.3%), and 2 patients with IBS-Mixed (6.7%) in IBS group. Student t-test and χ2 test were utilized in order to compare continuous and categorical variables between two groups, respectively. Results: Biochemical parameters did not differ between groups except for slightly increased creatinine in patients with IBS. cf-PWV and CIMT values were similar between groups. SDNN index and RMSSD were significantly impaired in patients with IBS compared to controls. Frequency analyses revealed lower LF, HF, and VLF in subjects with IBS. Conclusion: We demonstrated decreased parasympathetic modulation in patients with constipation predominant IBS. However, we could not demonstrate any changes in vascular structure and functions measured by carotid intima-media thickness and pulse wave velocity. Our results do not support accelerated atherosclerosis in IBS population (Anadol

The Effect of Treatment on Nitric Oxide and Asymmetric Dimethyl Arginine Levels in Asthma Patients

Giriş ve Amaç: Asimetrik dimetilarjinin (ADMA) ve nitrik oksit (NO), etkilerini birlikte gösterirler, bu moleküller arasındaki denge hava yolu tonusunun ve fonksiyonunun sıkı düzenlenmesine katkıda bulunmaktadır. Çalışmamızda astım tedavisinin serum ADMA, NO, düzeylerine solunum fonksiyon testlerindeki (SFT) değişimlerine, Total IgE, hemogram düzeylerindeki değişiklikleri belirlemeyi amaçlanmıştır. Gereç ve Yöntemler: Çalışmamızda astım tanısı konmuş 30 erkek/kadın hasta (40-60 yaş) ve benzer yaş grubunda 24 erkek/kadın kontrol grubu kullanılmıştır. Çalışmada tedavi öncesi ve sonrası hasta ve kontrol gruplarından serum ADMA, NO, Total IgE düzeylerine ELISA yöntemiyle ve hemogram düzeyleri ise otomatik kan sayım cihazında belirlenmiştir. Bulgular: Astımlı hastaların tedavi öncesi ve tedavi sonrası ADMA ve NO düzeyleri kontrol grubu ile arasında anlamlı fark bulunmuştur (p<0,001). Astımlı hastaların tedavi öncesi ve tedavi sonrası grupların total IgE düzeyleri kontrol grubu ile arasında fark istatistiksel olarak anlamlı bulunmuştur. (p<0,001). Astımlı hastaların tedavi öncesi ve tedavi sonrası grupların %FVC ve % PEF25−75% düzeyleri kontrol grubu ile arasındaki fark, tedavi öncesi grubun %FVC, %PEF25−75% düzeyleri tedavi sonrası grup arasındaki fark istatistiksel olarak anlamlı bulunmuştur (p<0,001). Sonuç: Astım hastalarında tedavinin hastalar üzerindeki etkileri bu çalışma ile belirlenmiş ve elde edilen veriler tedavi sonrası astım hastalarında iyileşme gözlenen parametre düzeylerinin astım hastalarında tedaviye yanıtın takibinin belirlenmesinde kullanılabileceği ortaya konmuştur.Objective: Asymmetric dimethyl arginine (ADMA) and nitric oxide (NO) show their effects together and the balance between these molecules contributes to the tight regulation of airway tone and function. In this study, we aimed to determine the changes in serum ADMA, NO, levels of pulmonary function tests (PFT), total IgE and hemogram levels of asthma treatment. Materials and Methods: In this study, 30 male / female patients (40-60 years) diagnosed with asthma and 24 male / female control groups of similar age group were used. In the study, serum ADMA, NO, Total IgE levels before and after treatment were determined by ELISA method using commercial kit and hemogram levels were determined by automatic blood counting device. Results: There was a significant difference between ADMA and NO levels in asthmatic patients before and after treatment (p<0.001). The difference between total IgE levels of asthmatic patients before and after treatment was found to be statistically significant (p<0.001). The difference between the FVC% and PEF25-75% levels of the pretreatment and post-treatment groups of the asthmatic patients with the control group and the %FVC and %PEF25- 75% of the pretreatment group were found to be statistically significant (p<0.001). Conclusion: The effects of treatment on asthmatic patients were determined in this study and it was shown that the parameter levels improved in asthmatic patients after treatment can be used to determine the response to treatment in asthmatic patients

a composite laminate veneer technique for diastema closure a report of ten cases

Aim: Diastemas can be treated using periodontal, surgical, orthodontic, or prosthetic procedures. Composite laminate veneers can be applied to reduce or eliminate diastemas and represent a good aesthetic non-invasive alternative for these patients. This study presents the treatment results of 10 patients with diastemas between the anterior teeth of the maxilla and mandible with composite veneers. Methodology: Ten patients with diastemas between the anterior maxillary and mandibular teeth complaining of esthetic problems were treated at the Department of Operative Dentistry, University of Dicle. The periodontal health of the patients was acceptable and no caries were detected. Patients were informed of the treatment choices and composite resin veneers were selected as the better approach for each case. The presence of a diastema causes esthetic problems, especially in adolescents. Prosthetic and conservative methods are usually used to treat diastemas because these approaches are minimally invasive. The direct laminate technique has the advantages of low cost, treatment reversibility, and easy repair of the restoration intraorally. The direct composite laminate technique has become more effective because of improvements in adhesive dentistry. Conclusion: This study describes a direct composite laminate technique for the restoration of the anterior teeth of 10 patients with diastemas. These restorations were conservative and provide an inexpensive, one-visit aesthetic treatment for anterior teeth. How to cite this article: Bahşi E, Callea M, İnce B, Montanari M, Dallı M, Batteli F, Akdoğan M, Gabriella C, Toptancı İR, Gabriela P, Yavuz İ. A Composite Laminate Veneer Technique for Diastema Closure: A Report of Ten Cases. Int Dent Res 2012;2:67-74. Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English

Real-world efficacy and safety of Ledipasvir plus Sofosbuvir and Ombitasvir/Paritaprevir/Ritonavir +/- Dasabuvir combination therapies for chronic hepatitis C: A Turkish experience

Background/Aims: This study aimed to evaluate the real-life efficacy and tolerability of direct-acting antiviral treatments for patients with chronic hepatitis C (CHC) with/without cirrhosis in the Turkish population.Material and Methods: A total of 4,352 patients with CHC from 36 different institutions in Turkey were enrolled. They received ledipasvir (LDV) and sofosbuvir (SOF)+/- ribavirin (RBV) ombitasvir/paritaprevir/ritonavir +/- dasabuvir (PrOD)+/- RBV for 12 or 24 weeks. Sustained virologic response (SVR) rates, factors affecting SVR, safety profile, and hepatocellular cancer (HCC) occurrence were analyzed.Results: SVR12 was achieved in 92.8% of the patients (4,040/4,352) according to intention-to-treat and in 98.3% of the patients (4,040/4,108) according to per-protocol analysis. The SVR12 rates were similar between the treatment regimens (97.2%-100%) and genotypes (95.6%-100%). Patients achieving SVR showed a significant decrease in the mean serum alanine transaminase (ALT) levels (50.90 +/- 54.60 U/L to 17.00 +/- 14.50 U/L) and model for end-stage liver disease (MELD) scores (7.51 +/- 4.54 to 7.32 +/- 3.40) (p<0.05). Of the patients, 2 were diagnosed with HCC during the treatment and 14 were diagnosed with HCC 37.0 +/- 16.0 weeks post-treatment. Higher initial MELD score (odds ratio [OR]: 1.92, 95% confidence interval [CI]: 1.22-2.38; p=0.023]), higher hepatitis C virus (HCV) RNA levels (OR: 1.44, 95% CI: 1.31-2.28; p=0.038), and higher serum ALT levels (OR: 1.38, 95% CI: 1.21-1.83; p=0.042) were associated with poor SVR12. The most common adverse events were fatigue (12.6%), pruritis (7.3%), increased serum ALT (4.7%) and bilirubin (3.8%) levels, and anemia (3.1%).Conclusion: LDV/SOF or PrOD +/- RBV were effective and tolerable treatments for patients with CHC and with or without advanced liver disease before and after liver transplantation. Although HCV eradication improves the liver function, there is a risk of developing HCC.Turkish Association for the Study of The Liver (TASL