Effect of Silica Fume as a Waste Material for Sustainable Environment on the Stabilization and Dynamic Behavior of Dispersive Soil

The use of dispersive soils, which are common in many parts of the world, in engineering applications such as water structures, earthen dams and road embankments is possible with their improvement. Recently, the effects of different chemicals on the stabilization of dispersive soils have been investigated. The use of waste materials in stabilization is preferred both because of the more sustainable environment and the economic advantages it provides. The use of silica fume (SF) as a waste material in different engineering applications provides an important advantage in environmentally and economically sustainable ways. Many studies have been carried out regarding silica fume, especially in the construction industry. Although SF is used in many industries, there is no study about its potential impact on the stabilization and dynamic properties of dispersive soils. In this study, first, Atterberg limits and standard Proctor compaction tests were performed on the mixtures prepared by adding different SF percentages (0, 5, 10, 15, 20, 25 and 30%). Afterward, pinhole tests and resonant column tests were performed to determine dispersibility and dynamic properties on the samples prepared by compaction characteristics for each SF percentage reached. In general, it was determined that SF contributed to a change in soil class, and improvement in dispersibility and dynamic properties of the soil sample, depending on SF content; positive effects of SF were observed in terms of shallow soil improvement

CONSTRUCTION OF FORMING LIMIT STRESS DIAGRAM OF AA 5754-O SHEET MATERIAL

Sac şekillendirme proseslerinde, sacın istenen şekli alması bölgesel boyunlaşma ve yırtılma hasarlarıtarafından sınırlanır. Bu proseslerde malzeme davranışını tahmin etmek için bilgisayar modelleri geliştirilmiştir.Bu modellerin gerçek durumu temsil edebilmesi için malzeme parametrelerine ihtiyaç vardır. Bu parametrelergenellikle çekme deneyi ve şekillendirme sınırını belirten diyagramlar ile elde edilir. Şekillendirme sınırınıbelirten diyagramlar sınır birim şekil değiştirme değerlerini gösteren şekillendirme sınır diyagramı ve sınırgerilme değerlerini gösteren şekillendirme sınır gerilme diyagramıdır. Şekillendirme sınır diyagramının hasar tahminini karmaşık ve birden fazla kademeli şekillendirme işlemlerindedoğru olarak tahmin edemediği, şekillendirme sınır gerilme diyagramının ise bu durumlarda da başarılı hasartahminlerinde bulunduğu literatürde belirtilmektedir. Bu çalışmada Al 5754-O malzemeye ait şekillendirme sınırgerilme diyagramı hem teorik hem de sayısal yöntemle elde edilmiştir.In sheet metal forming processes, local necking and fracture failures limit sheet metal form to desired shape.Computer models have been developed to estimate the material behavior in these processes. Material parametersare needed to represent the real forming processes. These parameters are generally obtained from tensile test andforming limit diagram. Diagrams that specify formability limit are forming limit diagram shows limit strains andforming limit stress diagram shows limit stresses. In literature, it is remarked that while forming limit diagram cannot estimate the failures for complex andgradual forming processes, forming limit stress diagram can successfully

The Relationship Between Business Cycle and Energy Prices in Turkey

anemonRecently it is observed an increase in businesscycle in Turkey. One of the most important factors affecting these fluctuationsis energy prices. In this study, relations between business cycle and energyprices are investigated using analysis of cross correlation, causalityanalysis, impulse response analysis and VAR model for the period of 1998-Q3 and2017-Q2 in Turkey. In the study, quarterly time series are used for thevariables of real gross domestic product, coal, oil and electricity priceindex. As a result of the analysis; it is observed that fluctuations in coal, oil and electricity prices move in reverse direction with business cycle andthat there is a one-way causality relationship from the electricity price indexto business cycle. Furthermore, the largest share of the change that may occuron business cycle has been found to be the change in electricity prices.Sondönemlerde Türkiye’de konjonktürel dalgalanmaların sıklaştığı ve boyutununarttığı gözlemlenmektedir. Bu dalgalanmaları etkileyen en önemli unsurlardanbiri enerji fiyatlarıdır. Bu amaçla çalışmada, Türkiye’de 1998-Q3 ve 2017-Q2dönemi için konjonktür dalgalanmaları ile enerji fiyatları arasındaki ilişkiçapraz korelasyon, nedensellik analizi, etki-tepki analizi ve VAR modeliyardımıyla analiz edilmektedir. Çalışmada reel gayrisafi yurtiçi hasıla, kömür, petrol ve elektrik fiyat endeksi değişkenlerine ilişkin üç aylık zaman serilerikullanılmıştır. Yapılan analiz sonucunda; kömür, petrol ve elektrik fiyatlarındaki dalgalanmaların her birininkonjonktürel dalgalanmalar ile ters yönde hareket ettiği ve elektrik fiyatlarındakidalgalanmalardan konjonktürel dalgalanmalara doğru tek yönlü bir nedensellikilişkisinin olduğu gözlemlenmiştir. Ayrıca konjonktürel dalgalanmalar üzerindemeydana gelebilecek değişimi açıklamada en büyük paya elektrik fiyatlarındakideğişimin sebep olduğu bulgusuna ulaşılmıştır.45264

Design, Fabrication and Performance Tests of a Double-sided Sheet Hydroforming Test System

314-322In this study, a double-sided sheet hydroforming (DSH) test system, which contains dies, sealing, pressure intensifiers, and a control unit, has been designed, built, and tested. The hydraulic numerical control system, which is currently used, has been modified as afour-axis where parameters are forming pressure, back pressure, punch position, and blank holder force. A hydromechanical deep drawing press has been modified in terms of die and sealing. New sealing components have been used to prevent leakage during the forming process because one side of the sheet is exposed to the forming pressure, and the other side is exposed to both the back pressure and the moving punch. Performance tests have been carried out to determine the limitations and capacity of the system. After the performance tests, it has been concluded that; the higher forming rates all along the process curve, the higher the pressure and force differences. However, the resultant error of the corresponding points has been only higher at the beginning of the process curve. In addition, the higher slopes in process curves have increased the pressure and force differences. A conical industrial part has been deformed by using hydromechanical deep drawing and DSH processes to test the performance of the DSH press. The wrinkling defect that occurred in previous hydroformed parts has been reduced remarkably by using back pressure in the DSH process. As a result, a double-sided sheet hydroforming test press has been successfully designed and manufactured. Finally, this study provides technical knowledge and can be used as a guideline for the design and performance evaluation of similar manufacturing systems

Effects of molsidomine on retinal ischemia/reperfusion injury in rabbits

Parlakpinar, Hakan/0000-0001-9497-3468; Ozhan, Onural/0000-0001-9018-7849WOS: 000435663500004PubMed: 29323543We investigated the effect of molsidomine (MOL) on ischemia/reperfusion (I/R) injury. Rabbits were assigned to four groups: group 1, sham; group 2, I/R; group 3, MOL treatment for 4days after I/R; group 4, MOL treatment for 1 day before I/R and 3days after I/R. Retinal I/R was produced by elevating the intraocular pressure to 150mm Hg for 60min. Seven days after I/R, the eyes were enucleated. Retinal changes were examined using histochemistry. The levels of malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) also were measured. We found a significant increase in the thickness of the outer nuclear layer of group 3 compared to the other groups. In groups 3 and 4, caspase-3 stained cells in the ganglion cell layer were decreased compared to group 2. We found a significant increase in caspase-3 stained cells in the inner nuclear layer (INL) of group 2 compared to the other groups. We found a significant increase in caspase-3 stained cells in group 3 compared to group 4 in the INL. The MDA level in group 2 was significantly higher than group 1 and MOL significantly decreased MDA levels in groups 3 and 4. We found that MOL protected the retina from I/R injury by enhancing antioxidative effects and inhibiting apoptosis of retinal cells

Serum Neopterin Levels and IDO Activity as Possible Markers for Presence and Progression of Hepatitis B

Chronic Hepatitis B virus (HBV) is still one of the major reasons for liver related mortality and morbidity all around the world. This study aimed to investigate the possible relationship between the immune system activation and presence, as well as progression, of hepatitis B infection by monitoring the tryptophan degradation and serum neopterin levels in patients with HBV. 110 patients with HBV and 23 healthy subjects were included in the study. The patients had significantly higher neopterin levels and increased kynurenine to tryptophan ratios, which were most probably due to enhanced indoleamine 2,3-dioxygenase (IDO) activity compared to healthy control. A strong positive correlation was found between neopterin levels and IDO activity in patient group. Neopterin levels and IDO activity were markedly increased in patients with histological activity index (HAI) ≥4 compared to HAI<4, and a significant correlation was found between neopterin and HAI. Moreover, there was a significant correlation between albumin levels and IDO activity in HBV patients. These findings suggest that tryptophan degradation results from IFN-γ-induced IDO activation, likewise depletion of albumin synthesis in HBV patients may result from diminished tryptophan availability. In conclusion, based on the study results, serum neopterin levels and IDO activity could provide additional immunological information for monitoring liver histological activity and can be used as prognostic markers in HBV disease