17 research outputs found
The History of Guided Bombs, Guidance Kits, Wing Kits, and Wing Deployment Mechanisms
The obligation of developed countries to achieve technological superiority for citizen security prompts significant defense budget allocations covering personnel, procurement, operations, maintenance, equipment, infrastructure, and research & development (R&D). Particularly, the R&D expenditures should not be considered a waste, since the money spent on R&D could return as battle superiority to alter the course of conflicts. Accordingly, the aim of this review paper is to provide knowledge on guided bombs, guidance kits, wing kits, and wing deployment mechanisms. The historical developments in the field were outlined, and the emergence of guided bombs and guidance kits were described chronologically with highlighting their strategic importance in previous conflicts. Also, a comparative analysis of the strengths and weaknesses of different guidance kits was presented. Besides, custom-made wing kits and wing opening systems were shown with relevant patents. Moreover, the critical role of wing kits in future conflicts, and the importance of continued research in this direction was emphasized. Finally, the current situation in the field was described with on-going challenges and possible solution proposals with an intention of serving as a guide for future studies
Cost-Effective Control of Molecular Weight in Ultrasound-Assisted Emulsion Polymerization of Styrene
This paper focuses on the determination of economically most feasible conditions to obtain polystyrene with various target molecular weights through ultrasound-assisted emulsion polymerization. Briefly, batch polymerizations of styrene have been performed by ultrasound-assisted emulsion polymerization process using different reaction feed compositions. Polymerization rates were calculated using the monomer conversions at various reaction times. Also, molecular weights of the synthesized polymers, as well as the Mark-Houwink constants, were determined by intrinsic viscosity and gel permeation chromatography measurements. It was found that the polydispersity index of the polymers is ranging from 1.2 to 1.5, and the viscosity average molecular weights are in between 100000-1500000 g/mol depending on the reaction conditions. Finally, model equations were also developed for response variables, and the most economical ways of reaching various target molecular weights were interpreted by response surface methodology based multi objective optimization
Graphene Oxide/Cholesterol-Substituted Zinc Phthalocyanine Composites with Enhanced Photodynamic Therapy Properties
In the present work, cholesterol (Chol)-substituted zinc phthalocyanine (Chol-ZnPc) and its composite with graphene oxide (GO) were prepared for photodynamic therapy (PDT) applications. Briefly, Chol-substituted phthalonitrile (Chol-phthalonitrile) was synthesized first through the substitution of Chol to the phthalonitrile group over the oxygen bridge. Then, Chol-ZnPc was synthesized by a tetramerization reaction of Chol-phthalonitrile with ZnCl2 in a basic medium. Following this, GO was introduced to Chol-ZnPc, and the successful preparation of the samples was verified through FT-IR, UV–Vis, 1H-NMR, MALDI-TOF MS, SEM, and elemental analysis. Regarding PDT properties, we report that Chol-ZnPc exhibited a singlet oxygen quantum yield (Φ∆) of 0.54, which is slightly lower than unsubstituted ZnPc. Upon introduction of GO, the GO/Chol-ZnPc composite exhibited a higher Φ∆, about 0.78, than that of unsubstituted ZnPc. Moreover, this enhancement was realized with a simultaneous improvement in fluorescence quantum yield (ΦF) to 0.36. In addition, DPPH results suggest low antioxidant activity in the composite despite the presence of GO. Overall, GO/Chol-ZnPc might provide combined benefits for PDT, particularly in terms of image guidance and singlet oxygen generation
Mustafa Kemal Atatürk
Tarihi ve medeniyeti yapan büyük insanlar gibi Atatürk'ün menşei, mütevazidir. Mustafa Kemal, halk çocuğudur. Demokrasi; soy asaleti değil, kan asaletidir; akıl ve zekâ aristokrasisidir. Demokrasi; ferdin, soyu ve menşei ne olursa olsun kendi değerine dayanarak, içtimai payelerin sonuna çıkabilmek hürriyeti ve imtiyazıdır. Mondros mütarekesi imzalanarak ordunun, silah ve cephanesi elinden alındığı, memleketin istila edildiği o meşum günlerde, Türkiye'nin bugünkü mesut geleceğine inanmak hülya gibi bir şeydi. Buna Mustafa Kemal inandı. Ümit havası yarattı. Zafere iman yarattı. Birinci Cihan Harbi'nden mağlûp ve bitkin çıkan kuvvetsiz ve sahipsiz kalan Türk milletine azim ve iman aşılamayı, onu kendi enerjisinin seviyesine yükseltmeyi ve büyük işler yapmaya sürüklemeyi bildi. Vatanın kurtuluş azmini kendinde şahıslandırdı
Mg-Ni Metaller Arası Bileşiklerinin Erimiş Tuz İçerisinde Üretilmesi
Mg2Ni, hidrojen depolama kapasitesi yüksek olan (3.4 ağ.%- 3.6 ağ. %) önemli bir metaller arası bileşiktir. Yapısında hidrojen ile kolay bağ kurabilen Mg bulunması depolamanın kolay olmasına, hidrojen ile kolay bağ kuramayan Ni bulunması da hidrojen ayrışımının kolaylaşmasına yardımcı olmaktadır. Literatür taraması yapıldığında Mg2Ni’nin bir çok çeşitli yöntemle üretilebildiği fakat bu yöntemlerin her birinde Mg ve Ni metallerinin üretim öncesinde hazır bulunması gerekliliği gözlemlenmiştir. Fakat magnezyum’un kolay oksitlenebilen bir metal olması, ayrı olarak tutulmasının da zor olmasına neden olmaktadır. Bu araştırma; Mg2Ni üretimi için yeni bir metodun uygulanabilirliğinin incelenmesini amaçlamaktadır. Bilindiği gibi Ni, NiO’in elektrodeoksidasyonu ile, Mg ise MgCl2’nin erimiş tuz içerisinde elektrolizi ile üretilebilmektedir. Bu iki metalin ayrı ayrı hücrelerde elde edilip daha sonra başka prosesler ile Mg2Ni bileşiği üretilmesi yerine tüm işlemin tek bir hücrede tamamlanması daha faydalı olacaktır. Bileşiminde MgCl2 bulunan bir elektrolit içerisinde, NiO elektrodeoksidasyonunu takiben uygulanacak yüksek potansiyellerin katotta Mg2Ni oluşumuna imkan verebileceği düşünülmüştür. Bu çalışmada temel amaç NiO elektrodeoksidasyonunu takiben yerinde Mg2Ni oluşturarak, önceki yöntemlere alternatif daha düşük maliyetli Mg2Ni metaller arası bileşiği oluşturmaktır. Sıcaklık, elektrik potansiyeli, erimiş tuz elektroliti kompozisyonu, NiO peletin porozitesi ve sinterleme süresi gibi değişkenlerin Mg-Ni metallerarası bileşiklerin oluşmasına etkilerinin incelenmesini kapsamaktadır. Sonuçta Mg2Ni oluşumuna yukarıdaki parametrelerin etkileri belirlenecektir
On the Preparation of Mg2Ni by Combining Electrodeoxidation and Electrolysis Techniques
Mg2Ni is a well-known hydrogen storage alloy. Most of the preparative methods for this alloy require high temperature processing of pure magnesium and nickel. The proposed method, studied in this work, involves the production of Mg2Ni alloy directly from NiO and MgCl2 in an electrochemical cell. This method can eliminate the difficulties that may arise, during handling due to the reactive nature of metallic components, especially Mg. XRD patterns of reduced samples indicated the partial formation of Mg2Ni. Experimental results also showed that sintering of NiO, which resulted in the decrease of porosities, adversely affects the formation of Mg-Ni intermetallic compounds. Such an observation was thought to be the result of higher molar volume of Mg2Ni as compared to that of NiO
Elektrodeoksidasyon ve erimiş tuz elektrolizi metotlarının intermetalik ve/veya alaşım üretmek için birleştirilmesi
Bu buluş, erimiş tuz elektrolizi ve elektrodeoksidasyon tekniklerini birleştirerek, intermetalik (metaller arası) bileşik ve/veya alaşım oluşturmayla ilgilidir. Daha özelde; intermetalik ve/veya alaşımın en az bir bileşeni, oksidinden veya başka bir bileşiğinden, oksijen veya başka bir metalik olmayan safsızlığın atılmasıyla elde edilmelidir. Benzer şekilde; intermetalik ve/veya alaşımın en az bir bileşeni, hedeflenen intermetalik bileşik ya da alaşımı oluşturmak üzere, erimiş tuz elektrolitlerinden, klasik erimiş tuz elektrolizi yöntemiyle oluşturulmalıdır
AN INVESTIGATION INTO THE ELECTROCHEMICAL PRODUCTION OF Si BY THE FFC CAMBRIDGE PROCESS
The FFC Cambridge process was suggested as a promising Si production technique for the expanding solar energy industry. Direct electrochemical reduction of bulk SiO2 plates and porous SiO2 pellets in molten CaCl2-NaCl salt mixture were investigated at 750 degrees C by applying 2.8 V potential difference. The produced Si powder was brown and found to be contaminated by the Ni and stainless steel plates used as the cathode contacting materials. The reduction rates of the bulk SiO2 plates and porous SiO2 pellets were compared from variations of current and accumulative electrical charge that passed through the cell during the electrochemical reduction. The amorphous bulk SiO2 plates were reduced slightly faster than porous pellets of crystalline SiO2. The overall reduction potential of SiO2 pellets against the graphite anode at 750 degrees C in molten CaCl2- NaCl salt mixture was determined as 2.3 V by cyclic voltammetry. This potential was supported by calculations