SEMPOZYUM BİLİM KURULU SEMPOZYUM DÜZENLEME KURULU

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2 SEMPOZYUM BİLİM KURULU Prof. Dr. Zehra AKDENİZ Prof. Dr. Sevim AKYÜZ Prof. Dr. A. Nihat BERKER Prof. Dr. Bedia ERİM BERKER Prof. Dr. Can Fuat DELALE Prof. Dr. Gülay DERELİ Prof. Dr. Bekir KARAOĞLU Prof. Dr. Mustafa KESKİN Prof. Dr. Ş. Erol OKAN Prof. Dr. Oktay SİNANOĞLU Prof. Dr. Yani SKARLATOS Prof. Dr. Bilal TANATAR Prof. Dr. Hasan TATLIPINAR Prof. Dr. Mehmet TOMAK Prof. Dr. İskender YILGÖR Prof. Dr. Ersin YURTSEVER Piri Reis Üniversitesi Kültür Üniversitesi Sabancı Üniversitesi İstanbul Teknik Üniversitesi Işık Üniversitesi Yıldız Teknik Üniversitesi Beykoz Lojistik MYO Erciyes Üniversitesi Trakya Üniversitesi Yale Üniversitesi Boğaziçi Üniversitesi Bilkent Üniversitesi Yıldız Teknik Üniversitesi Ortadoğu Teknik Üniversitesi Koç Üniversitesi Koç Üniversitesi SEMPOZYUM DÜZENLEME KURULU Prof. Dr. Zehra AKDENİZ Yrd. Doç. Dr. Zeynep ÇİÇEK ÖNEM Yrd. Doç. Dr. Ali KARAMAN Yrd. Doç. Dr. Gülşen AKIN EVİNGÜR Hanifi ARSLAN Piri Reis Üniversitesi İstanbul Üniversitesi İstanbul Üniversitesi Piri Reis Üniversitesi Piri Reis Üniversitesi

3 Sıvıhal Fiziği Çalışma Grubu 15. ULUSAL SIVIHAL FİZİĞİ SEMPOZYUMU Kasım 2011 Piri Reis Üniversitesi, Tuzla-İstanbul 24 Kasım 2011, Perşembe Kayıt PROGRAM Açılış Konuşmaları Prof.Dr. Osman Kamil Sağ ( Piri Reis Üniversitesi Rektörü) Prof.Dr. Zehra Akdeniz (Piri Reis Üniversitesi- Fen Edebiyat Fakültesi Dekanı, Sıvıhal Fiziği Sempozyum Koordinatörü) Denge,Deniz, Strateji, Rekabet Dr. Mühendis Ekber Onuk (Yonca Onuk Tersanesi) :40 BREAK / ARA Denizin Farklı Kültürleri Sargun A. Tont (Sabancı Üniversitesi) SU: Fiziği, Nanofiziği, Kimyası ve Jeopolitiği Sondan Feyiz Durukanoğlu (Sabancı Üniversitesi) Denizlerdeki Biyolojik Kirlenmeyi Önlemek Amacıyla Geliştirilen Poliolefin Kaplamalar ile Ulva Sporlarının Yüzeylerden Uzaklaştırılması Arasındaki İlişki İkrime Orkan Uçar, C. Elif Özen Cansoy, H. Yıldırım Erbil (Piri Reis Üniversitesi)

4 ÖĞLE YEMEĞİ 13: Bistability of a two- mode BEC in an optical cavity S.Safaei, O.E.Mustecaplioğlu, B.Tanatar (Bilkent Üniversitesi) Computational design of metal borohydrides and metal ammines for energy storage Adem Tekin (İstanbul Teknik Üniversitesi) Su Dalgalarının Modellenmesi ve Uygulamaları Serdar Beji (İstanbul Teknik Üniversitesi) Araştırma ve Erişim Odaklı Eğitim Nihat Berker (Sabancı Üniversitesi) SEMPOZYUM KOKTEYLİ 25 Kasım 2011, Cuma Stability of spin-orbit coupled Fermi gases with population imbalance Levent Subaşı (İstanbul Teknik Üniversitesi) Sol-Gel Phase Transitions in Composite Gels Gülşen Akın Evingür, Önder Pekcan (Piri Reis Üniversitesi) Quantum Phase Transitions in Atomic Condensates Coupled to Driven Dissipative Optical Cavities Özgür E. Müstecaplıoğlu (Koç Üniversitesi) Dynamical properties of a coupled nonlinear dielectric waveguide surface-plasmon josephson junction system Yasa Ekşioğlu, Özgür E. Müstecaplıoğlu, Kaan Güven (Koç Üniversitesi)

5 BREAK / ARA Çeşitli metal kümelerinin katı-sıvı faz geçişleri Meral Eryürek, M. H. Güven (Karaelmas Üniversitesi) DFT study of rhenium-doped boron clusters: ReB n (n=1-15) Servet Kurt, M. Böyükata, Z. B. Güvenç (Bozok Üniversitesi) 11: Part I. Experimental Study of Riboflavin-Dextran and Riboflavin-Dextrin Solutions Nur Mustafaoğlu, Gülşen A. Evingür, Buse Özen, F. Gülay Acar, Gönül Özen (İstanbul Teknik Üniversitesi) Part II. Theoretical Study of Riboflavin-Dextran and Riboflavin-Dextrin Solutions Buse Özen, Nur Mustafaoğlu, Gülşen A. Evingür, F. Gülay Acar, Gönül Özen (İstanbul Teknik Üniversitesi) ÖĞLE YEMEĞİ Spontaneous Formation of A Nanotube From A Square Ag Nanowire: An Atomistic View Mine Konuk, Sondan Feyiz Durukanoğlu (İstanbul Teknik Üniversitesi) Modifiye Aljinat Jellerinden Protein Salımı Hakan Kaygusuz, F. Bedia Erim (İstanbul Teknik Üniversitesi) Embedded Atom Method Potential for Ni-Cu Alloys and Its Applications for Ni, Cu growth on Cu(111) Berk Onat, Sondan Feyiz Durukanoğlu (İstanbul Teknik Üniversitesi)

6 BREAK / ARA Ground-state configurations of few interacting bosons confined in two dimensions by anisotropic harmonic potential. A. İhsan Meşe, Pablo Capuzzi, Saban Aktaş, Zehra Akdeniz, S.Erol Okan (Trakya Üniversitesi) Density of State and Localization Properties in Optical Lattices with Speckle Disorder Serpil Sucu, Saban Aktaş, S.Erol Okan, Zehra Akdeniz, Patrizia Vignolo (Trakya Üniversitesi) The potential profile of quantum well under the laser and electric fields Figen Karaca Boz, Saban Aktas, Şevket Erol Okan (Trakya Üniversitesi) Denizlerdeki Hazine Gülaçtı Topçu (Bezmialem Vakıf Üniversitesi)

7 Denge,Deniz, Strateji, Rekabet Dr. Mühendis Ekber Onuk Yonca Onuk Tersanesi

8 Denizin Farklı Kültürleri Sargun A. Tont Sabancı Üniversitesi

9 SU: Fiziği, Nanofiziği, Kimyası ve Jeopolitiği Sondan Durukanoğlu Feyiz Sabancı Üniversitesi 21. yüzyılda petrölün yerini alabileçeğinin tartışıldığı şu günlerde su'ya yaşamsal değerinin yanında ekonomik değer de eklenince, su hemen hemen her türlü ekonomik aktvitenin içersinde yer alır oldu. Bu önem, su'yu bir cok bilimsel ve sosyo-ekonomik projelerin ilgi odağına koydu. Bu konuşmamda değişik perspektiflerden bakarak, doğanın bize sunduğu ve kaygusuzca tüketmeye devam ettiğimiz suyu tanıtmaya çalışacağım.

10 Denizlerdeki Biyolojik Kirlenmeyi Önlemek Amacıyla Geliştirilen Poliolefin Kaplamalar ile Ulva Sporlarının Yüzeylerden Uzaklaştırılması Arasındaki İlişki İkrime ORKAN UÇAR, 2 C. Elif ÖZEN CANSOY 1 ve H. Yıldırım ERBİL 2 1 Piri Reis Üniversitesi, İstanbul, Türkiye ceozen@yahoo.com 2 Gebze Yüksek Teknoloji Enstitüsü, Kimya Mühendisliği Bölümü, Kocaeli, Türkiye iorkan@gyte.edu.tr, yerbil@gyte.edu.tr Deniz ortamı ile temas halinde olan yüzeyler üzerinde mikroorganizmalar, algler ve diğer deniz canlılarının tutunması sonucunda biyolojik kirlenme meydana gelir. Biyolojik kirlenmenin sonucunda, gemilerin hızında, manevra kabiliyetlerinde ve yakıt tüketimlerinde olumsuz etkiler ortaya çıkar. Biyolojik kirlenmeyi ve bunun beraberinde getirdiği olumsuz etkileri ortadan kaldırabilmek için gemi boyalarının yüzey serbest enerjisi 1, mekanik özellikleri 1, ıslanabilirliği 2 ve pürüzlülüğü 3,4 gibi özellikleri değiştirilerek daha az kirlenen boyalar sentezlenebilir. Islanabilirlik önemlidir ve o yüzeyin kimyasal kompozisyonu ve pürüzlülüğü değiştirilerek kontrol edilebilir. Yüzeyin geometrik mikro yapısının kontrolü de deniz ortamında biyolojik türlerin yüzeylere yapışmasını engellemede önemli rol oynar. Bu çalışmanın 5 amacı serbest yüzey enerjisi değerleri birbirine yakın olan poliolefin polimer ve kopolimerler kullanarak hazırlanan mikro desenli yüzeylerin temas açısı histeresizi (CAH) ve ıslanabilirlik histeresizi (WH) değişimi ile deniz ortamındaki türlerin (Ulva sporları) yüzeylerden uzaklaştırılması arasındaki ilişkiyi incelemektir. Bu amaçla, polipropilen (PP) ve yüksek yoğunluklu polietilen (HDPE) polimerleri ile polipropilenpolietilen (PPPE) ve etilen-vinil asetat (EVA-12; 12% VA) kopolimerleri kullanılarak yüzeyler sentezlenmiştir. Ulva sporlarının yüzeylerden uzaklaştırılabilme özellikleri ile polimer ve kopolimer yüzeylerinin temas açıları ve ıslanabilirlik histeresizleri arasında doğrusal bir ilişki olduğu bulunmuştur. Ulva sporlarının yüzeylerden uzaklaştırılabilme kolaylıkları PP > HDPE > PPPE > EVA-12 şeklindedir ve histeresizdeki (CAH ve WH) artış sporların yüzeylerden uzaklaştırılma yüzdelerinin artmasına neden olmaktadır. Referanslar 1. R. F. Brady and I. L. Singer, Biofouling 15, 73 (2000) 2. M. E. Callow, J. A. Callow, L. K. Ista, S. E. Coleman, A. C. Nolasco, and G. P. Lopez, Appl. Environ. Microbiol. 66, 3249 (2000). 3. J. Genzer and J. Groenewold, Soft Matter 2, 310 (2006). 4. J. F. Schumacher, M. L. Carman, T. G. Estes, A. W. Feinberg, L. H. Wilson, M. E. Callow, J. A. Callow, J. A. Finlay, and A. B. Brennan, Biofouling 23, 55 (2007). 5. Ikrime O. Ucar, C. Elif Cansoy, H. Yildirim Erbil, Michala E. Pettitt, Maureen E. Callow, and James A. Callow, Biointerphases, 5(3), (2010).

11 Bistability of a two- mode BEC in an optical cavity S.Safaei, O.E.Mustecaplioğlu, B.Tanatar Bilkent Üniversitesi We use the self-consistent mean-field theory to analyze the effects of Rashba-type spin-orbit coupling (SOC) on the ground-state phase diagram of populationimbalanced Fermi gases throughout the BCS-BEC evolution. We find that the SOC and population imbalance are counteracting, and that this competition tends to stabilize the uniform superfluid phase against the phase separation. However, we also show that the SOC stabilizes (destabilizes) the uniform superfluid phase against the normal phase for low (high) population imbalances. In addition, we find topological quantum phase transitions associated with the appearance of momentum space regions with zero quasiparticle energies, and study their signatures in the momentum distribution.

12 Computational design of metal borohydrides and metal ammines for energy storage Adem Tekin Informatics Institute, Istanbul Technical University, Maslak Istanbul Turkey By combining several computational methods, the lowest energy crystal structures of Mg(NH 3 ) n Cl 2 with n=6,2,1, Mg(BH 4 ) 2, LiBH 4 and NaBH 4 were searched. Furthermore, NH 3 ab- and desorption mechanisms involved in metalammines were investigated using a combination of DFT and quasi-elastic neutron scattering measurements.

13 Stability of spin-orbit coupled Fermi gases with population imbalance Levent Subaşı İstanbul Teknik Üniversitesi, İstanbul We use the self-consistent mean-field theory to analyze the effects of Rashbatype spin-orbit coupling (SOC) on the ground-state phase diagram of population-imbalanced Fermi gases throughout the BCS-BEC evolution. We find that the SOC and population imbalance are counteracting, and that this competition tends to stabilize the uniform superfluid phase against the phase separation. However, we also show that the SOC stabilizes (destabilizes) the uniform superfluid phase against the normal phase for low (high) population imbalances. In addition, we find topological quantum phase transitions associated with the appearance of momentum space regions with zero quasiparticle energies, and study their signatures in the momentum distribution.

14 SU DALGALARININ MODELLENMESİ VE UYGULAMALARI S. Beji İstanbul Teknik Üniversitesi, Gemi İnşaatı ve Deniz Bilimleri Fakültesi Maslak 34469, İstanbul Su dalgalarının modellenmesi için derinlik integre edilmiş denklemlerin türetilmesi, çeşitleri ve kullanım alanları incelenmektedir. Diğer yaklaşımlara göre derinlik integre edilmiş dalga modellerinin üstünlükleri belirtilerek farklı uygulamalara ait örnek simülasyonlar verilmektedir. Kıyı ve liman bölgelerindeki dalga hareketleri, deniz dibinden su yüzeyine uzanan yapılara etkiyen dalga kuvvetleri ve tsunami simülsayonları gibi uygulamalar örneklerle gösterilmektedir.

15 Araştırma ve Erişim Odaklı Eğitim Nihat Berker Sabancı Üniversitesi

16 Sol- Gel Phase Transitions in Composite Gels Gülşen Akın Evingür 1 and Önder Pekcan 2 1 Piri Reis University, 34940, Tuzla, Istanbul, TURKEY, gulsen.evingur@pirireis.edu.tr 2 Kadir Has University, 34083, Cibali, Istanbul, TURKEY, pekcan@khas.edu.tr The composite gels were prepared with different amounts of monomers such as kappa- carrageenan (κc), N- isoproplacrylamide (NIPA), multiwalled carbon nanotube (MWNT) and sodium alginate (SA) in polyacrylamide (PAAm). The sol- gel phase transitions in the composite gels were characterized by the steady state fluorescence technique (SSF). Pyranine was added as a fluoroprobe for monitoring the polymerization. Pyranine added to the pre-polymerization solution presented a spectral shift to the shorter wavelengths upon the initiation of polymerization. This spectral shift is due to the binding of pyranine to the polymer chains during the composite polymerization. The fluorescence intensity of the pyranine bonded to the strands of the composite gels allows one to measure directly the gel fraction and average degree of polymerization near the sol-gel phase transition. In this study, we aimed to study the gelation of the composites and determined the gel fraction exponent, β and the weight average degree of polymerization exponent, γ for this composite system. For this purpose, the aqueous solutions of various monomers composites were prepared. The universality of composite gels could be described by classical and percolation exponents during the sol-gel phase transition in PAAm-κC [1], PAAm- NIPA[2], PAAm-MWNT [3] and PAAm- SA[4]. It is found that the critical exponents did not obey the same universality class, where the most important factor is the monomer content in which the exponents differ drastically from percolation to the classical values in the composite gels. References [1] D. Kaya Aktaş, G. Akın Evingur, Ö. Pekcan, Universal Behaviour of Gel formation from Acrylamide-Carrageenan Mixture around the Gel Point: A Fluorescence Study. Journal of Biomolecular Structure and Dynamics, (1): p [2] G. Akın Evingur, D. Kaya Aktaş Ö. Pekcan, Steady state fluorescence technique for studying phase transitions in PAAm- PNIPA mixture. Phase Transitions, (1): p [3] D. K.Aktaş, G. Akın Evingur, Ö. Pekcan, Critical exponents of gelation and conductivity in Polyacrylamide gels doped by multiwalled carbon nanotubes. Composite Interfaces, : p [4] G. A. Evingür, F. Tezcan, F. B. Erim and Ö. Pekcan, Monitoring the Gelation of Polyacrylamide - Sodium Alginate Composite by Fluorescence Technique, Phase Transitions, 2011, in press.

17 Quantum Phase Transitions in Atomic CondensatesCoupled to Driven Dissipative Optical Cavities Özgür E. Müstecaplıoğlu (Koç Üniversitesi) We examine structural dynamical phase transition of an ultracold gas of bosonic atoms coupled to a driven dissipative optical cavity. The atomic condensate is pumped along the direction transverse to the cavity axis. Above a certain threshold of the pumping strength, the condensate undergoes a dynamical quantum phase transition where the continuous translational symmetry is broken and a crystalline structure is emerged. Atomic phase transition is accompanied by quantum phase transition of the cavity photons. Cavity field exhibits so called Dicke superradiance phase transition. The governing equations of the system describe the coupled cavity field and condensate field dynamics. Imaginary and Real time simulations are performed to solve the system of equations. The results are shown to be in agreement with the actual experiment [1]. In addition we analyse the collective excitations of the coupled field-condensate system. Photodetection methods, stochastic resonances and excitations and hierarchy of multipole excitations are discussed. [1] K. Baumann, C. Guerlin, F. Brennecke and T. Esslinger, arxiv: [quantph].

18 Dynamical properties of a coupled nonlinear dielectric waveguide surface-plasmonjosephson junction system Yasa Eksioglu, Ozgur E. Mustecaplioglu, Kaan Guven We demonstrate that a weakly-coupled nonlinear dielectric waveguide surface-plasmon (DWSP-JJ) system can be formulated as in analogy to bosonic Josephson junction of atomic condensates at very low temperatures yet exhibits different dynamical features. Such a system can be realized along a metal - dielectric interface where the dielectric medium hosts a nonlinear waveguide (e.g. fiber) for soliton propagation. The inherently dynamic coupling parameter generates novel features in the phase space.

19 ÇEŞİTLİ METAL KÜMELERİNİN KATI-SIVI FAZ GEÇİŞLERİ M..ERYUREK, M. H. GUVEN Zonguldak Karaelmas Üni.Fen-Ed. Fak. Fiz. Böl.,Zonguldak,TÜRKİYE Parçacıklar arası etkileşmeleri Gupta Potansiyeli ile tanımlanan çeşitli metal kümelerinin mikrokanonik Moleküler Dinamik simülasyon yöntemi ile katı-sıvı faz geçişleri incelenmiştir. Bu süreçte ilk aşamada her bir sabit enerji değerine karşılılık gelen simülasyonlara ait potansiyel enerjiler, kinetik sıcaklıklar ve kümedeki atomların koordinatları hesaplanmıştır. İkinci aşamada elde edilen sonuçlar kullanılarak kalorik eğriler ile bağ uzunluğundaki dalgalanmaların kare ortalamalarının kare kökü eğrileri elde edilmiştir. Üçüncü aşamada ise iki farklı yöntem kullanılarak, kanonik ve mikrokanonik termodinamik (ısı kapasitesi, entropi, termodinamik sıcaklık, potansiyel enerji dağılımı) nicelikler elde edilmiştir. Bu sonuçlardan kümelerin katı-sıvı faz geçişlerinin özellikleri ve erime sıcaklıklarının belirlenmesinde yararlanılmıştır. Çalışma; entropi eğrilerinden elde edilen potansiyel enerji dağılım fonksiyonlarının davranışının, faz geçişlerinin karakteristiğini belirlemek için kullanışılı bir yöntem olduğu görüşüne ulaşılmasını sağlamıştır.

20 DFT study of rhenium-doped boron clusters: ReB n (n=1-15) S. KURT 1, M. BÖYÜKATA 1, Z. B. GÜVENÇ 2 1 Department of Physics, Bozok University, Yozgat, Turkey 2 Department of Elect. and Comm. Eng., Çankaya University, Ankara, Turkey Bare boron [1] and metal-doped boron [2,3] clusters have been an interesting subject in nanosized finite cluster studies due to the importance for hydrogen hosting [4]. There are also considerable interest on Rhenium clusters, Re n (n=1-8), [5] and Re-B binary clusters [6] owing to their potential applications in constructing nanostructured materials. In this preliminary work the geometry optimizations have been carried out for Re doped boron microclusters, ReB n (n=1-15), by using DFT/B3LYP functional and Cep-4G basis set [7]. Structural and energetic analysis have been realized for the obtained possible lower-lying energy configurations. The results are compared with pure B n clusters and any boron-metal complexes. Acknowledgment. This work is supported by Bozok University (BAP-I.F.E.F/ ) References [1] Atış, M., Özdoğan, C., Güvenç, Z.B., J. Quantum Chem., 107, 3, 729, (2007). [2] Liu, X., Zhao, G.F., Guo, L.J., Jing, Q., Luo, Y.H., Phys. Rev. A 75, , (2007). [3] Böyükata, M., Güvenç, Z.B., J. Alloys Comp. 509, 4214 (2011). [4] Böyükata, M., Güvenç, Z.B., Int. J. Hydrogen Energy 36, 8392 (2011). [5] Feng, X.J., Cao, T.T., Zhao, L.X., Lei, Y.M., Luo, Y.H., Eur. Phys. J. D 50, 285 (2008). [6] Feng, X.J., Zhao, L.X., Cao, T.T., Lei, Y.M., Luo, Y.H., Physica B 403, 432, (2008). [7] Frisch M. J. et. al., GAUSSIAN 03, Revision D.01, Gaussian Inc., Wallingford, CT, (2004).

21 Part I. Experimental Study of Riboflavin Dextran and Riboflavin Dextrin Solutions Nur Mustafaoğlu 1, Gülşen Akın Evingür 2, BuseÖzen 3,F. Gülay Acar 4*, Gönül Özen 4 1 İstanbul Technical University, Institute of Science and Technology, Nano Science and Nano Engineering, İstanbul, Turkey 2 Piri Reis University, 34940, Tuzla, Istanbul, Turkey 3 İstanbul Technical University, Institute of Science and Technology, Physics Engineering, 34469Maslak, İstanbul, Turkey 4 İstanbul Technical University, Faculty of Sciences and Letters, Physics Engineering Department, İstanbul, Turkey * acarg@itu.edu.tr Riboflavin is B2 vitamin and both dextrin and dextran are polysaccharide. The only difference between dextrin and dextran is their linked; in dextran α-(1,3) and α-(1,6) linked exists between α-d-glucopyranosyl residues while in dextrin α-(1,4) or α-(1,6) glycosidic bonds are existed. The length of the dextran molecule is between Da and Da which is appropriate for the cross-linking reaction in biological systems and polymeric gels. Dextrin is derived from potato which color is white and has similar properties with dextran to use in cross-linking reactions. In this study, absorption spectrum and fluorescence spectrum of both riboflavin dextran and riboflavin dextrin solutions for different concentrations from 0,01 to 1 M have been measured. Furthermore, time-drive measurement and analysis of the solutions have been investigated. According to results from the experiments, physical parameters of the solutions such as diffusion coefficient and quantum yield have been calculated. Comparison of these two solutions has been shown as tables and graphics.the theoretical model andcalculations are going to be presented in our other presentation that explains the theoretical part of our study.

22 Part II. Theoretical Study of Riboflavin Dextran and Riboflavin Dextrin Solutions Buse Özen 1, Nur Mustafaoğlu 2, Gülşen Akın Evingür 3, F. Gülay Acar 4*, Gönül Özen 4 1 İstanbul Technical University, Institute of Science and Technology, Physics Engineering, 34469Maslak, İstanbul, Turkey 2 İstanbul Technical University, Institute of Science and Technology, Nano Science and Nano Engineering, İstanbul, Turkey 3 Piri Reis University, 34940, Tuzla, Istanbul, Turkey 4 İstanbul Technical University, Faculty of Science and Letters, Physics Engineering Department, 34469Maslak, İstanbul, Turkey * acarg@itu.edu.tr In this study theoretical modelling has been done after our experiments that have been conducted in order to determine the physical parameters about the specific chemical solutions. Riboflavin-Dextran and Riboflavin-Dextrin solutions have the ability to create crosslinks between fibrilles in the biological tissues.these solutions cause the generation of free oxygen radicals by the excitement of UV light without harming the biological tissues. These oxygen radicals are formed to tide amino groups of the collagen fibrilles by covalent bond.hence, interfibrilles cross-linking enhances the resistant and rigidity. These solutionswere compared in order to decide which one has more advantage than the other one. According to the results of ourexperiments, similar absorption and emission spectras were obtained for both of these two solutions. Riboflavin-Dextran and Riboflavin-Dextrin solutions were compared by the help of graphics and the physical parameters such as cure depth and diffusion coefficient. Physical parameters were calculated in a theoretical diffusion model. The emmision and absorption graphics are going to be presented in our other presentation that explains the experimental part of our study. This study will lead to cure the biological tissues and will be the additional treatment for compliance process after organ transplantation.

23 Spontaneous Formation of A Nanotube From A Square Ag Nanowire: An Atomistic View M. Konuk 1, S. Durukanoglu 2, 3 1 Department of Physics, Istanbul Technical University, Maslak, Istanbul, Turkey 2 Faculty of Engineering and Natural Sciences, Sabanci University, Orhanli, Tuzla Istanbul, Turkey 3 Nanotechnology Research and Application Center, Sabanci University, Orhanli, Tuzla Istanbul, Turkey We have performed molecular static calculations to investigate the recently observed phenomenon of the spontaneous formation of a nanotube from a regular, square Ag nanowire[1,2]. In the simulations, atoms are allowed to interact via the model potential obtained from the modified embedded atom method[3]. Our simulations predict that this particular type of structural phase transformation is controlled by the nature of applied strain, length of the wire and initial cross-sectional shape. For such a perfect structural transformation, the <100> axially oriented fcc nanowire needs (1) to be formed by stacking A and B layers of an fcc crystal, both possessing the geometry of two interpenetrating one-lattice-parameter-wide squares, containing four atoms each, (2) to have an optimum length of eight layers, and (3) to be exposed to a combination of low and high stress along the length direction. The results further offer insights into atomistic nature of this specific structural transformation into a nanotube with the smallest possible cross-section. This work was supported by TUBITAK under Grant No. 109T105. Computations were carried out through UYBHM at Istanbul Technical University, under Grant No [1] M. J. Lagos, F. Sato, J. Bettini, V. Rodrigues, D. S. Galvao, and D. Ugarte, Nature Nanotech. 4, 149 (2009). [2] P. A. S. Autreto, M. J. Lagos, F. Sato, J. Bettini, A.R. Rocha, V. Rodrigues, D. Ugarte and D. S. Galvao, Phys. Rev. Lett. 106, (2011).

24 [3] M. I. Baskes, Phys. Rev. B 46, , (1992); B-J Lee., J-H Shim, and M. I. Baskes, Phys. Rev. B 68, (2003). ModifiyeAljinat Jellerinden Protein Salımı Hakan Kaygusuz, F. Bedia Erim İstanbul Teknik Üniversitesi Bir polisakkarit olan aljinat, çok değerlikli katyonlar ile suda çözünmeyen jeller oluşturmaktadır. Bu jeller amaca uygun olarak modifiye edilebilir. Bu amaçlar arasında ilaç salım denemeleri de yer almaktadır. Bu çalışmada kil katkılı kalsiyum aljinat kürelerinin insan vücuduna sindirim yoluyla alımı taklit edilerek, model protein olarak seçilmiş sığır serumu albümininin çeşitli çözeltilere salımı incelenmiştir. Hazırlanan küreler karakterize edilmiş ve salım ortamlarındaki davranışları da takip edilmiştir.

25 Embedded Atom Method Potential for Ni-Cu Alloys and Its Applications for Ni, Cu growth on Cu(111) Berk Onat 1, Sondan Durukanoğlu 2,3 1 Informatics Institute, İstanbul Technical University, 34469, İstanbul, Turkey 2 Faculty of Engineering and Natural Sciences, Sabancı University, 34956, İstanbul, Turkey 3 Nanotechnology Research and Application Center, Sabancı University, 34956, İstanbul, Turkey We developed a semi-empirical, many-body type model potential to investigate static and dynamic properties of Ni-Cu alloys. The formalism is based on the embedded atom method [1] with improved optimization techniques. The Ni-Cu alloy potential was determined by fitting to data on lattice parameters, cohesive energies for L1 0, L1 1, L1 2, and L1 3 phases, together with vacancy formation energies, bulk modulus and elastic properties for L1 2, L1 3 phases. Our preliminary calculations for energy barriers for the diffusing Ni and Cu atoms on Cu(111) based on the nudged elastic band method are found to be consistent with the available experimental and other theoretical results. Our ultimate goal is to describe the varying characteristics in growing islands of pure Cu, Ni atoms and mixed Ni-Cu combinations on Cu(111) [2]. [1] Voter A. F., and Chen S. P., Mat. Res. Soc. Symp. Proc., 82, 175, (1987) [2] S. Pons et al., Surf. Sci., 511, 449, (2002) This work was supported by TUBITAK under Grant No. 109T105. Computations were carried out through UYBHM at Istanbul Technical University, under Grant No

26 Ground-state configurations of few interacting bosons confined in two dimensions by anisotropic harmonic potential A.I. Mese 1, P.Capuzzi 2, S.Aktas 1, Z. Akdeniz 3 and S.E. Okan 1 1 Department of Physics, Trakya University, Edirne, Turkey 2 Instituto de F ısica de Buenos Aires, Consejo Nacional de Investigaciones Cient ıficas y T ecnicas, Argentina 3 Piri Reis University, Tuzla, Istanbul, Turkey We studied the ground-state configurations of few bosons confined by a two dimensional anisotropic harmonic potential and K 0 interaction potential [1] relying on a minimal variational approach based in Gaussian wave functions. The ground state energies and the density profiles have been obtained for the systems of bosonic Rubidium atoms with their number ranging from two to nine [2]. It has been shown that the bosonic atoms are driven from a two dimensional configuration to that of one dimensional, if the anisotropy parameter is small. In addition, the transition criterions between Bose-Einstein Condensate and Wigner Crystallization have been determined by developing an analytical method[3]. The results obtained are compared with the published numerical and experimental results [4,5]. References [1] Nelson D.R., and Seung H.S., Phys. Rev. B (1989). [2] A. I. Mese, P. Capuzzi, Z.Akdeniz, S.E.Okan and M.P. Tosi J.Phys , 2008 [3] A.I.Mese, P.Capuzzi,S.Aktas,Z.Akdeniz and S.E.Okan Phys. Rev.A 84, (2011) [4] S. W. S. Apolinario,et al., Phys. Rev. E 72, [5] M Saint Jean and C Guthmann, J. Phys. Condens. Matter 14,

27 Density of State and Localization Properties in Optical Lattices with Speckle Disorder Serpil Sucu 1, Saban Aktaş 1, S.Erol Okan 1, Zehra Akdeniz 2, Patrizia Vignolo 3 1 Department of Physics, Trakya University,22030, Edirne 2 Piri Reis University, Tuzal-İstanbul, Edirne 3 Universite de Nice-Sophia Antipolis, Institut non Lineaire de Nice, CNRS, 1361 route des Lucioles, Valbonne, France We study the localization properties and density of state of non-interacting wawes propagating in a speckle-like potential superposed on a one-dimensional lattice. To study the effect of a speckle potential in the presence of a 1D lattice on matter-wave transport we use the 1D tight-binding Hamiltonian where site energies are squaresinc-correlated random variables. By decreasing the width of the correlation function, the disorder patterns approaches a -correlated disorder, and the localization length becomes almost energy-independent in the strong disorder limit. We show that at fixed and large disorder strength, the localization efficacy of the speckle potential depends strongly on the width of the auto-correlation function w.

28 V D (mev) E B (mev) The potential profile of quantum well under the laser and electric fields. Figen Karaca Boz 1, Saban Aktas, 1* and Sevket Erol Okan 1 1 Department of Physics, Trakya University, Edirne 22030, Turkey The potential profile in the various quantum wells is investigated under the laser, and electric fields. The calculations are made by using finite different and variational methods within the effective-mass approximation. It can also be seen that the shape of potential profiles of quantum well becomes important as the differences between binding energies emphasized more when the electric and laser fields are applied in comparison with the presence of the electric field only. In recent years, the many studies related to the external fields acting on the binding energy in a single and double quantum wells have been reported [1-11]. An external electric field application to these structures causes a polarization on the carrier distribution. The binding energy in the quantum well can be decreased or increased depending on the location of the impurity and the electric field direction applied. The joint action of a laser and electric field on the binding energy is depended on the strength of the fields in the quantum well. In this work, we will focus on studying the potential profile of the various quantum well under the laser and electric fields. The binding energy of the impurity in the various quantum wells is investigated under the laser, and electric fields. Fig. 1 shown effect of the combination of laser and electric fields on the potential profile in double parabolic quantum well (DPQW), and double square quantum well (DSQW) in the z-direction DPQW DSQW F=20kV/cm =25A o 9,0 DPQW DSQW 0 =25 A o 8,5 z i =0 z i (L A +L B )/ ,0 z i (L A +L B )/ z(a o ) 7,5 b F(kV/cm) Fig. 1. The potential profile of the DPQW, and DSQW in the z-direction for α 0=25A o under the electric field F=20kV/cm, the dimensions are L A=50A o and L B=25A o. Fig. 2. The binding energy of the DPQW, and DSQW structures as a function of the electric field for different the impurity position. In the laser field parameter is α 0=25A o. The effect of the electric field on the binding energy in DPQW, and DSQW with L A=50A o and L B=25A o is calculated for different impurity positions in Fig. 2 with laser field. In summary, we showed that the shape of potential profiles of quantum wells becomes important as the differences between binding energies emphasized more when the electric and laser fields are applied in comparison with the presence of the electric field only..*corresponding author: figenb@trakya.edu.tr [1] E. Ozturk, I. Sokmen, Superlatt. Microstruct., 48(2010) 312. [2] E. Kasapoğlu, H Sari., I. Sökmen. Physica B 390 (2007) 216. [3] E. Kasapoglu, I. Sökmen, Physica E 27 (2005)198. [4] Q. Fanyao, A. L. A. Fonseca, and O. A. C. Nunes, Phys. Stat. Sol. 8b) 197 (1996) 349. [5] O. A. C. Nunes, A. L. A. Fonseca, F. M. S. Lima, D. A. Agrello, Solid State Communications 122 (2002) 425. [6], F. M. S. Lima, M. A. Amato, L. S.F. Olavo, O. A. C. Nunes, A. L. A. Fonseca, and E. F. da Silva, Physical Review B 75 (2007) [7] E. Ozturk, H. Sari, I. Sokmen, Solid State Comm. 132 (2004) 497. [8] L. M. Burileanu, E. C. Niculescu, N. Eseanu, A. Radu, Physica E 41 (2009) 86. [9] E. C. Niculescu, A. Radu, M. Stafe, Superlattices and microstructures 46 (2009) 443. [10] N. Eseanu, Physics Letters A 374 (2010) [11] E. C. Niculescu, N. Eseanu, Superlattices and microstructures 48 (2010) 416.

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