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Aim: In this study our purpose was to compare the digital subtraction angiography (DSA) and computed tomography angiography (CTA) techniques in terms of the superiority of diagnosis and radiation doses. Materials and Methods: Forty-six patients (21 men, 25 women) who were subjected to both digital subtraction angiography (DSA) and computed tomography (CT) neck-brain angiographic examinations between January and December 2014 were screened retrospectively. Radiation dose records taken from the cards provided by DSA and CT devices were reviewed. The total DSA [DSA+ tri-dimension (3D) DSA], DSA, 3D-DSA and CTA dose reports were examined separately. Generated 3D images were evaluated by two radiologists who had experience in neuro radiology and interventional radiology at least for five years. Independent samples test and in dual comparisons the paired samples test, were used for statistical analyses. Results: Comparison made between DSA and CTA radiation doses has found that the total dose of total DSA (DSA+3D DSA) was three times and the DSA doses were two times higher than the CTA dose. There was no statistical difference between 3D DSA and CTA doses. CTA is less sensitive than DSA; four of 68 intracranial aneurisms could not be demonstrated with CTA. The radiation doses received by patients did not change with gender. Conclusion: CTA contains less radiation doses in the diagnosis of intracranial aneurisms, but its sensitivity, however, is lower than DSA., Amaç: Bu çalışmada amacımız tanı ve radyasyon dozlarının üstünlüğü açısından dijital subtraksiyon anjiyografi (DSA) ve bilgisayarlı tomografi anjiyografi (CTA) tekniklerini karşılaştırmaktır. Gereç ve Yöntem: 2014 yılı Ocak-Aralık tarihleri arasında hem DSA hem de CTA ile boyun-beyin anjiyografik muayeneye tabi tutulan 46 hasta (21 erkek, 25 kadın) retrospektif olarak tarandı. DSA ve CT cihazları tarafından sağlanan kartlardan alınan radyasyon dozu kayıtları gözden geçirildi. Toplam DSA (DSA + 3D-DSA), DSA, 3D-DSA ve CTA dozu raporları ayrı ayrı incelendi. Oluşturulan üç boyutlu görüntüler en az beş yıl nöroloji ve girişimsel radyolojide tecrübesi olan iki radyolog tarafından değerlendirildi. İstatistiksel hesaplamalarda Independent samples testi, ikili karşılaştırmalarda ise paired samples testi kullanıldı. Bulgular: DSA ve CTA radyasyon dozları arasında yapılan karşılaştırmada, toplam TDSA dozunun [DSA + 3 boyutlu (3D) DSA], CTA dozundan 3 kat fazla olduğu ve DSA dozunun, CTA dozundan 2 kat daha fazla olduğu bulundu. 3D DSA ve CTA dozları arasında istatistiksel bir fark yoktu. CTA, DSA'dan daha az duyarlı idi; 68 intrakranial anevrizmanın dördü CTA ile kanıtlanamadı. Hastalar tarafından alınan radyasyon dozları cinsiyetle değişmedi.Sonuç: CTA intrakranial anevrizma tanısında daha az radyasyon dozu içerir, ancak duyarlılığı DSA'dan daha düşüktür.

Ill ÖZET Emet ve Bigadiç'ten sağlanan kolemanit minerali (2Ca0.3B203. 5HpO) örneklerinin kimyasal analizi, atomik absorbsiyonu, İR ve X-ray spektrumları alınarak bu örneklerin kolemanit yapısında olduğu kanıtlandı. örnekler kırılma, eleme ve dehidratasyon operasyonlarına tabi tutuldu. Elde edilen analiz sonuçları ve dehidratasyon bul guları Emet kökenli kolemanit örneklerinin, Bigadiç kökenli ör neklere göre içlerinde elektroliz açısından istenmeyen bazı gayrı safiyetler (Fe203, Si02, AlgOo, MgO ve SrÖ) içerdiğinden, elek troliz işlemleri Bigadiç kökenli anhidrit hale getirilmiş kolema nit örneklerine uygulandı. Bigadiç kökenli saf anhidrit kolemanit (2Ca0.3B203) ile anhidrit kalsiyum klorür (CaCl2) belli oranlarda karıştırılarak 900°C ile 1100°C arasında 150 dakika süre ile uygulanan 6-7 volt luk bir gerilim ve 20 amperi i k bir akım altında grafit pota (ka tot) ve grafit çubuk (anot) kullanılarak elektroliz edildi. Pota nın duvarlarında ve dibinde toplanan siyah renkli parlak, kristalIV manzarası görünümünde ve fakat kristal olmayan ürün, pota sıcak iken kazınarak alındı. Kazınarak alınan katot ürünü, hidroklorik asit (HC1) ile ekstrakte edildi. Daha sonra bu madde çeşitli çözücülerle mua mele edilip yıkandıktan sonra, bir etüve alındı. 110°C'da bir gece etüvde bekletilen madde iyice kuruduktan sonra, İR, atomik absorbsiyon ve klasik kimyasal analizlerine tabi tutuldu. Söz konusu maddenin kalsiyum hekzaborür (CaBg) yapısında olduğu sap tandı. Bu sonuca dayanarak, çalışmada uygulanan elektroliz yönte mi ile kalsiyum hekzaborür (CaBg) üretiminde olduğu gibi; Türki ye'deki diğer bor minerallerinden farklı metal borürl erinde üretiminin gerçekleştirilebileceği kanısına varılmıştır. SUMMARY ELECTROCHEMICAL PRODUCTION OF CALCIUM BORIDE FROM TURKISH COLEMANITE The colemanite and tincal reserves together comprise the major part of the boron mineral deposits of Turkey, Since there are large deposits of colemanite which is a mineral having the composition represented by 2Ca0.3B203.5H20 in Emet and Bigadiç. It was worthwhile to investigate the electrolytic product of the calcium boride (CaBg) which has an increasing industrial impor tance. Calcium boride (CaBg) has recently found some important commercial applications, being used chiefly in the deoxidation of copper and other nonferrous alloys it is also a convenient source of boron for the preparation of other metallic borides and of boron alloys, as elemental boron. Colemanite mineral samples were taken from the vein near the country of Emet in the Kütahya province and near the country of Bigadiç in the Balıkesir province are subjected to X-Ray, IRVI and chemical analyses by atomic absorption spectrometry. 3 g. of each colemanite sample, ground in order to pass 80 mesh, was first dehydrated for 2 hrs at different tempera tures and optimum conditions for the dehydration was determined. 200°C, 300°C, 400°C 500°C and 550°C degrees for hours periods and at the end of e//ery 15 minutes dehydrated samples were weighed. It was found that at at 550°C samples were reached to constant-weight and at this temperature percentage of the loss of water was found to be 21,88 %. This result was in good agreement with theoretical value of 21,91 % which is calculated from 2Ca0.3B203.5H20. The dehydrated colemanite samples were subjected to elemen tal, IR and X-ray analyses. For the electrolytic production of calcium boride, an electric resistance furnace was initially designed a graphite crucible was placed in the furnace as a cathode, and graphite electrodes were used as anode. In some experiments, a small -scale' electrolytic cell was used. The dehydrated colemanite samples were electrolysed between 900-1 100°C in the presence of calcium chloride which lower the melting point. The portions of colemanite samples were added periodically to the cell during the course of the electrolyses.VII The best operating conditions for the electrolysis of calcium boride (CaBg) were as follows : To determine optimum conditions of bath composition, electrolysis was carried out with several different bath compositions of colemanite and calcium chloride (CaClo). The reactions taking place during the electrolysis may be indicated as follows : (I) (2) (3) 10 CaO 10 Ca+3 B203 10 C+5 02 hMO Ca +5 02 -»»CaBg 4- 9 CaO -^10 CO The calcium chloride (CaCl2) takes no part in the reaction and is utilized merely as a flux and to increase the fluidity and conductivity of bath.VIII It will be noted from reaction (2) that a considerable amount of calcium oxide (CaO) is formed at the cathode. After the completion of each electrolysis experiments, the contents of cell were leached and extracted with hydro chloric acid (HC1) to remove calcium oxide (CaO), Boron oxide (BpOo) and calcium chloride (CaClp). Black and brilliant crystals which were obtained after extraction processes, washed with water, ethanol and ether and later they were dried in an oven at 110°C degrees for 24 hours. The yield was found to be 42% from the following eguation. Yield product ; M.I. t m = Z.F in this eguation,.1 m s= Amount of calcium hexzaboride deposited of the cathode. M= Number of moles of calcium hexzaboride deposited of cathode. Z = Number of electrons transferred. I =Total amount of current pasied through electrolyte, t «Electrolysis time F ;=Fara.«lay constantsIX According the faraday law, M.I. t m theoretical ~` Z.F m n = experimental x 100 m theoretical This product was subject to elemental and IR analyses. The result of chemical analyses of electrolysis product calcium hexzaboride (CaBg) and of dehydrated colemanite mine ral are summarized in the following table. As a result of this investigation, it was concluded that a high grade of calcium boride (CaBg) from Turkish colemanite (Bigadiç) can be produced at relatively low temperatures by this method, and other Turkish boron minerals could also be used as raw materials for the production of other metal borides, 110

Ill ÖZET Alumina ve alüminyum üretiminin cna hammaddesi hidrate - Al^ü^ minerali olan boksit cevheridir. Boksit cevherlerinin ana komponentleri, A1~0~, SiÖ~, Fe~CL, TiO? ve rLÖ şeklindedir. Ay rıca az miktarda organik maddeler, Mn, P, V, Cr, Mi, Ga, Ca, F v.b. de içerirler. Bugün dünya alümina üretiminin % 90'ından fazlası Bayer Teknolojisi ile gerçekleştirilmektedir. Ülkemizde, 1973 yılında işleve geçen Seydişehir Alüminyum Tesislerinde, boehmitik karak terdeki Mortaş, Değirmenlik ve Doğankuzu yatakları boksitleri Bayer Prosesi ile işlenmektedir. Yurdumuzda bu bölgenin dışında, 1960'tan sonra Ki. T. A. ta rafından ağırlık verilen tarama çalışmaları ile saptanmış, çe şitli boksit yataklarımız bulunmaktadır. Her boksit cevherinin kimyasal ve mineralojik yapısı farklı olduğundan, bu farklılık lara bağlı olarak, alümina üretimleri de farklı proses paramet relerinde gerçekleştirilir. Bu parametrelerin saptanması için de laboratuvar araştırmalarına gereksinim vardır. Araştırma konusu olarak saptanan, Türkiye'de işlenmeyen Zonguldak (Kokaksu) bölgesi boksitleri kimyasal ve mineralojik yönden incelenmiş, x-ray faz analizi ile cevherin tipi diaspo- rik olarak saptanmıştır. Araştırma konusu cevherin mineralojik tipinin diasporik oluşu çalışmaya ayrı bir özellik vermiştir. Zira diasporik cevherler, bugün dünyada, endüstriyel ölçüde, Çin, Vietnam, Romanya ve Sovyetler Birliğinde işlenmektedir. A1203 (%53,20) ve Si02 (%3, 10 II class bauxite, if the value is : M= 7-10 IIIr class bauxite, if the value is : M= 4-7 XL IV class bauxite, if the value is : U = 2.6-4 th V class bauxite, if the value is : M< 2.6 Generally the bauxites are ore-grade for the Bayer-techno logy with a module 7 or more and with 40% of Al-O^-content or more. Based on the experiences of the alumina plants some parts of the chemically analysed Al-0, content can never be recovered. This Al-O-, content is two times (in some cases three times) higher than that of the reactive SiO- content. Based on these, the formula of the Basic Equivalent or Bev can be worked as follows : Bev = Al20gt - 2Si02% or : AljOg*. - 3Si02% It is the Bayer-technology that is used worldwide in the industrial processing of the bauxites. More than 90% of the world's total alumina is produced by this technology. This technology involves great demands on the investigation and analy sis. The composition of bauxite to be processed, the efficiency of digestion, moreover the getting injto solution of the conta minants should be known.VII The most important operations in the Bayer Process are as follows : crushing the bauxite (wet grinding in the presence of the digesting liquor is the usual modern practice) ; digestion (at a pressure of 1 to 40 atmospheres and temperatures of 100 to 250 C or even higher) in continuous digesting lines that generally consist of autoclaves and in sometimes of simple tanks ; dilution of slurry obtained after digestion; separation of the non-digested residue (red mud) by settling and washing in counter flow decan- tation ; followed by filtration ; further purification of the saturated sodium-aluminate solution by filtration, cooling and crystallization (decomposition) in presence of seed alumina ; filtration and washing of the product ; calcination at 1,100 to 1,200 C ; and recirculation of the spent liquor to the wet grindinc or to the digestion stages after evaporation and making up with fresh caustic soda to compensate for any losses. The total ore reserve in Turkey is determined by M.T.A. as 430 million tons. In our country the alumina production is only made in Seydişehir Alumina Plant with Bayer Process. In the mentioned plant, the alumina production is made with boehmitic bauxites from the regions of Mcrtaş, Doğankuzu and De ğirmenlik. Since each baxite reserve has different chemical and mine- ralogical composition, the economical investigation must be made according to characteristics of the ores. The other bauxite reserves in Turkey apart from the region of Seydişehir are not investigated from the point of chemical, mineralogical composition and production of alumina.VIII The aim of this study is the evaluation bauxite reserve of Zonguldak (Kokaksu region) in respect of alumina production end the determination of technological parameters depending on the quality of bauxite. The representative samples arriving from the mines of Kokak su region has been crushed, ground and sieved according to ASIM E- 11 in order to extract its Al-O, content with high efficiency. According to the results of the chemical and qualitative phase analysis, the type of bauxite which is investigated has been determined as diasporic. Since the ore is diasporic, 4% CaO has been added to each digestion test. The digestion tests for determining the optimum parameters 3 have been carried out in steel autoclave of 500 cm capacity, equipped with mechanic stirrer, and by direct electric heating. The digestion tests have been made with sodium-alurninate solu tions at different caustic molar ratios to get A1?0~ content of bauxite into solution at contant temperature and pressure. At the end of each digestion test, aluminate liquor has been separated from the red mud by the aid of centrifuge. After filtrating and washing, red mud samples have been dried on 110°C for a night and ground minus 100 y for chemical analysis and minus 63 y for x-ray investigation. The following chemical components have been determined in the red mud samples : '; L.0.1. Si02 Fe203IX Al2°3 Ti02 CoO No20 c X-Ray diffractograms have been taken by x-ray instrument- DPOH-1. From the results of chemical analysis of bauxite and red muds, the actual recovery of alumina, specific bauxite consump tion, specific red mud production and the bound Na^O and Al^O^ losses have been determined for each of parameter. According to the results of chemical and mineralogical phase anolysis of the red muds, in experiment 19 we investi gated that the actual alumina recovery has been exceeded to the theoretical one. As shown from the x-ray diffractogram of the red mud pro duced from this experiment, the diaspor phase has been entirely got into solution. ' From the point of economy, the optimum parameters have been gained in this experiment. The above mentioned experiment has been carried out at the parameters which are pointed out below : Temperature 220 * 5 C Pressure 21-33 atm. Digestion time 30 minutes Caustic molar ratio of digestion liquor 3.7Required molar ratio of aluminate liquor 1.6 Caustic Na~0 content of digestion liquor 300 g/1 In this experiment the values that influence the economy f the process, have been determined as, the experimental A190~ recovery, 96.48% ; bauxite^consumption, 1.928 t/t alumina ; red iud production, 0.831 t/t alumina ; the bound Na-O and Al?0_ losses, 42.879 and 36.065 kg/t alumina, respectively. o m 113