Browsing by Author "Erdogan, Y"

Now showing 1 - 12 of 12
  • No Thumbnail Available
    Item
    Kinetics for fast pyrolysis of hazel nut shell
    Demirbas, A; Akdeniz, F; Erdogan, Y; Pamuk, V
    In this article, the potential utilization of hazel nut shell as a combustible residue was studied. To obtain liquid and gaseous products, the hazel nut shell was subjected to pyrolysis and it was converted to 49.3 % (w) gaseous and 20.0 % (w) liquid products at 475 degrees C for 7.5 minutes in a simple pyrolysis device. The kinetic model used in the present study was based on fractional weight loss for each pyrolysis step. The simple fast pyrolysis was compared with TGA technique.
  • No Thumbnail Available
    Item
    Analyses of boronic ores and sludges and solubilities of boron minerals in CO2-saturated water
    Erdogan, Y; Aksu, M; Demirbas, A; Abali, Y
    In this study, the potential of boron in Turkey, commercial most-used compounds of boron and their production trends according to years and analyses of boronic samples obtained different sources were investigated. Besides classic analysis technics, X-ray fluorescence spectrometric (XRF) and flame photometric methods were carried out for boronic samples. Chemical compositions of original and concentrated samples were studied with respect to the contents of B, Li, Ca, Al, Fe, Mg, S, As, Si, Sr and Na. The leaching of boric acid with CO2-saturated water from boron minerals was also investigated. (C) 1998 Elsevier Science B.V. All rights reserved.
  • No Thumbnail Available
    Item
    Dehydration kinetics of howlite, ulexite, and tunellite using thermogravimetric data
    Erdogan, Y; Zeybek, A; Sahin, A; Demirbas, A
    In this study, some boron mineral samples (howlite, ulexite and tunellite) have been analysed by DTA and TG methods. The thermochemical reactions of these boron compounds have been studied. The dehydration kinetic parameters for howlite, ulexite and tunellite were activation energies: 65.0, 39.5 and 50.4 kJ mol(-1); the pre-exponential factors: 50.8 x 10(5), 6.60 x 10(5), 32.4 x 10(5) s(-1) and rate constants: 70.1, 113.1 and 82.3 s(-1), respectively, at a constant heating rate of 10 K min(-1). The average particle size was 200 mu m for all samples. The order of dehydration reactions (n) was accepted as first order. (C) 1999 Elsevier Science B.V. All rights reserved.
  • No Thumbnail Available
    Item
    Potentiometric titration of some dicarboxylic acids in non-aqueous media
    Aslan, A; Erdogan, Y; Demirbas, A; Karslioglu, S
    Five dicarboxylic acids; adipic acid, azelaic acid, suberic acid, dodecandioic acid and tetradecandioic acid were titrated potentiometrically with tetrabutylammonium hydroxide in five different non-aqueous solvents; tert-butyl alcohol, isopropyl alcohol, acetone, pyridine and N,N-dimethylformamide. The pKa values of the compounds were determined in the solvents mentioned above.
  • No Thumbnail Available
    Item
    Cement mixes containing colemanite from concentrator wastes
    Erdogan, Y; Zeybek, MS; Demirbas, A
    Ln this article, colemanite ore wastes of particle size <25 mm and sludge from concentrator were dried by hot air flow and then were mixed with Portland and trass cements. The effects on the setting and mechanical properties of the colemanite ore wastes mixed with Portland and trass cements were investigated. It was found that some colemanite wastes can be used as cement additives. (C) 1998 Elsevier Science Ltd.
  • No Thumbnail Available
    Item
    Effects of supplementary cementing materials on the properties of cement and concrete
    Targan, S; Olgun, A; Erdogan, Y; Sevinc, V
    The effect of bentonite, colemanite ore waste (CW), coal fly ash (FA) and coal bottom ash (BA) on the properties of cement and concrete has been investigated through a number of tests. The properties examined include setting time, bending strength, volume expansion, compressive strength and water consistency of the mortar. The result showed that setting time of the cements was generally accelerated when bentonite replaced a part of the cement. Bentonite exhibited a significant retarding effect when used in combination with CW in Portland cement at lower replacement level and showed an accelerating effect at higher replacement level. Although the inclusion of bentonite at replacement levels of 5-10% resulted in an increase in compressive strength at early ages, it decreased the compressive strength when used in combination with other materials. The results obtained were compared with Turkish standards and, in general, were found to be acceptable. (C) 2002 Elsevier Science Ltd. All rights reserved.
  • No Thumbnail Available
    Item
  • No Thumbnail Available
    Item
    Influence of natural pozzolan, colemanite ore waste, bottom ash, and fly ash on the properties of Portland cement
    Targan, S; Olgun, A; Erdogan, Y; Sevinc, V
    This study has examined the effect of natural pozzolan (NP), colemanite ore waste (CW), coal fly ash (FA), and coal bottom ash (BA) on the properties of cement and concrete. The parameters studied included compressive strength, bending strength, volume expansion, and setting time. A number of cements were prepared (in the presence of fixed quantity of 10% FA, 10% BA, and 4% CW) by the replacement of Portland cement (PC) with NP in range of 5 - 30%. The results showed that the final setting time of cement pastes were generally accelerated when the NP replaced part of the cement. However, NP exhibited a significant retarding effect when used in combination with CW. The results also showed that the inclusion of NP at replacement levels of 5% resulted in an increase in compressive strength of the specimens compared with that of the control concrete. The replacement of PC by 10 - 15% of NP in the presence of fixed quantity of CW improves the bending strength of the specimens compared with control specimens after 60 days of curing age. (C) 2003 Elsevier Science Ltd. All rights reserved.
  • No Thumbnail Available
    Item
    An investigation on the use of tincal ore waste, fly ash, and coal bottom ash as Portland cement replacement materials
    Kula, I; Olgun, A; Sevinc, V; Erdogan, Y
    The possibility of using tineal ore waste (TW), coal bottom ash (BA), and fly ash (FA) as partial replacement in concrete was examined through a number of tests. The properties examined include setting time, compressive strength, mortar expansion, water consistency of mortar, and microstructure. The results showed that compressive strength of all specimens containing I wt.% of TW was higher than that of the control at the 28th day of curing. At 90 days, the contribution to strength by BA + TW and FA + TW was higher than in the concrete-prepared equivalent TW beyond 3 wt.% of Portland cement (PC) replacement. With the replacement of 3-5 wt.% of PC by TW, the compressive strength of the concrete decreased compared to control concrete. However, the values obtained are within the limit of Turkish Standards (TS). Adding BA or FA with TW improved the performance relative to TW replacement only. Increasing replacement of TW gives rise to a higher setting time. As a result. TW, BA, and FA samples may be used as cementitious materials. (C) 2002 Elsevier Science Ltd. All rights reserved.
  • No Thumbnail Available
    Item
    Effect of Asbestos Exposure on the Frequency of EGFR Mutations and ALK/ROS1 Rearrangements in Patients With Lung Adenocarcinoma A Multicentric Study
    Yilmaz, S; Demirci, NY; Metintas, S; Zamani, A; Karadag, M; Guçlu, OA; Kabalak, PA; Yilmaz, U; Ak, G; Kizilgoz, D; Ozturk, A; Yilmaz, U; Batum, O; Kavas, M; Serifoglu, I; Unsal, M; Komurcuoglu, BE; Cengiz, TI; Ulubay, G; Ozdemirel, TS; Ozyurek, BA; Kavurgaci, S; Alizoroglu, D; Celik, P; Erdogan, Y; In, E; Aksoy, A; Altin, S; Gunluoglu, G; Metintas, M
    Objective: The aim of this study is to investigate the effect of asbestos exposure on cancer-driver mutations. Methods: Between January 2014 and September 2018, epidermal growth factor receptor (EGFR), anaplastic lymphoma receptor tyrosine kinase (ALK), and c-ros oncogene 1 receptor tyrosine kinase gene (ROS1) alterations, demographic characteristics, asbestos exposure, and asbestos-related radiological findings of 1904 patients with lung adenocarcinoma were recorded. Results: The frequencies of EGFR mutations, ALK, and ROS1 rearrangements were 14.5%, 3.7%, and 0.9%, respectively. The rates of EGFR mutations and ALK rearrangements were more frequent in asbestos exposed non-smokers (48.7% and 9%, respectively). EGFR mutation rate was correlated to female gender and not-smoking, ALK rearrangement rate was correlated to younger age, not-smoking, and a history of asbestos exposure. Conclusions: The higher rate of ALK rearrangements in asbestos-exposed lung adenocarcinoma cases shows that asbestos exposure may most likely cause genetic alterations that drive pulmonary adenocarcinogenesis.
  • No Thumbnail Available
    Item
    Frequency of Mutations and Related Factors in Lung Adenocarcinoma Cases in Turkey
    Yilmaz, S; Karadag, M; Demirci, N; Kizilgöz, D; Kabalak, PA; Metintas, M; Ak, G; Yilmaz, U; Komurcuoglu, B; Guclu, O; Ozturk, A; Ozdemirel, T; Cengiz, TI; Ozyurek, B; Erdogan, Y; Altin, S; Celik, P; Gunluoglu, G; Ulubay, G; Zamani, A; Kavas, M; Tatar, D; Metintas, S
  • No Thumbnail Available
    Item
    Influence of colemanite admixture on Portland cement durability
    Erdogmus, E; Targan, S; Erdogan, Y; Avciata, U; Gencel, O
    In this study, the compressive strength of mortar prepared by Portland cement (PC) and different proportions of blast furnace slag, fly ash and colemanite concentrator waste was examined at the end of the 2nd, 7th, 28th, 60th and 90th days. Moreover, some mortars were kept in 50 g/l sodium sulfate (Na2SO4) solution according to ASTM C1012 for 6 months to determine their sulfate resistance. The first length of some mortars made with alkali reactive sand together with additives mentioned above or PC according to ASTM C1260 was measured to detect their alkali-aggregate reaction resistance and then their final lengths were measured after being kept in 1 M sodium hydroxide (NaOH) solution at a temperature of 80 degrees C for 14 days. The results were compared both among themselves and with Portland cement. In addition, the microstructures of some samples scanned by scanning electron microscopy were photographed. It was found that all the additives had positive effects on sulfate and ASR resistance.