Artan enerji taleplerin karşılanmasında yenilenebilir enerji türleri açısından popüler olan fotovoltaik teknolojiler üzerine verim artırmaya yönelik çalışmalar yapılmaktadır. Boya duyarlı güneş pilleri yüksek altyapı maliyeti gerektirmeyen yapılar olduğundan verim artırmaya yönelik çalışmalar boya duyarlı güneş hücreleri (DSSC) üzerine yoğunlaşmıştır. DSSC’de ışığa duyarlı boya, TiO2 tabakasına tutundurulmaktadır. Kullanım ömrünü tamamlamış NiTi alaşımı endodontik eğeler, farklı asitler üzerinden çözeltiye alınıp metalik değerlerine ayrıştırılmış ve bu metalik değerlerden olan anataz fazında olduğu tespit edilen TiO2 ‘nin boya duyarlı güneş hücrelerinde kullanımına yönelik çalışmalar yapılmıştır. Çalışma kapsamında atık NiTi eğelerden elde edilen kontamine TiO2 ‘nin yapısı karakterize edilmiş ve N719 boya çözeltisinin yüzeye tutundurularak optik özellikleri araştırılmıştır. Boya duyarlı güneş hücrelerinde kullanılan N719 boya çözeltisi uygulanan geri kazanım anataz TiO2 tatbik edilmiş yüzeyle ile görünür bölge spektrumunda belirgin bir etkinlik göstermediği ortaya konulmuştur.
Nickel -titanium based alloys are widely used as a root canal file in dental canal treatment in endodontics. According to the Turkish Ministry of Health, approximately, two million root canal treatments were applied yearly in Turkey. Ni-Ti rotary files have been used for 80 % of these endodontic root canal treatments. Rotary files contain 55-60 wt.% nickel and 40-45 wt.% titanium. Ni-Ti endodontic files can be recovered by hydrometallurgy, which is an economical way, instead of treating them as medical waste. The aim of this study is to provide economical hydrometallurgical recycling of metallic wastes that cannot be recovered by direct melting. Nickel and titanium based endodontic rotary files were recovered via using different leaching techniques in high corrosive environments such as dissolution in concentrated acid, baking in sulfuric acid and hydrothermal treatment in concentrated sulfuric acid. The acid concentration, temperature and time parameters were optimized for concentrated sulfuric acid leaching in autoclave. The acid baking method is a simple system more efficient than the pure dissolution in acid. At the end of the hydroxide structures dehydration, TiO 2 (anatase) and NiO powders were obtained. Moreover, under pressure within non-stirring autoclave the rotary file is completely dissolved with a cost-effective two-step process. Thus, an efficient recycling process has been created for waste Ni-Ti alloy tooth files.
Nickel and titanium-based alloys are commonly used for engineering or medical applications. At the end of their lifetime NiTi alloys are recycled as additive materials. Separate recovery of metals present in NiTi alloy is possible via hydrometallurgical methods, however NiTi alloys are highly resistive towards corrosion. Different mineral acids (H2SO4, HCl, HNO3, H3PO4) have been investigated and the effect of presence of H2O2 in leaching medium has also been explored. Different leaching yields have been observed and correlation between them according to treatment conditions have been established. Microstructure and chemical properties of alloys were characterized by SEM, XRF and EDS techniques. Among mineral acids, H2SO4 and HCl illustrated the highest extraction efficiencies. Nevertheless addition of hydrogen peroxide decreased this efficiency severely. Throughout kinetics of dissolution were obtained through decreased leaching efficiency with addition of hydrogen peroxide.
This review is based on how to measure particle sizes with different image processing techniques. In addition to this, particle size significantly affects the mechanical properties of the material. In material science, structure of the material is analyzed to understand that a material can provide certain standards, such as toughness and durability. Therefore, it is a great importance to make this measurement carefully and accurately. The segmentation approach, which is frequently used in image processing, aims to isolate objects in an image from the background. In this sense, the separation of particles from the background can be considered as a problem of the image processing. In image processing applications, there are different approaches used in segmentation such as histogram-based, clustering-based, region amplification, separation and merging. In this review, a comparative analysis was made by examining recent studies on particle size measurement.
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