SEMPOZYUM BİLİM KURULU

Prof. Dr. Zehra AKDENİZ Piri Reis Üniversitesi

Prof. Dr. Sevim AKYÜZ Kültür Üniversitesi

Prof. Dr. A. Nihat BERKER Sabancı Üniversitesi

Prof. Dr. Bedia ERİM BERKER İstanbul Teknik Üniversitesi

Prof. Dr. Can Fuat DELALE Işık Üniversitesi

Prof. Dr. Gülay DERELİ Yıldız Teknik Üniversitesi

Prof. Dr. Bekir KARAOĞLU Beykoz Lojistik MYO

Prof. Dr. Mustafa KESKİN Erciyes Üniversitesi

Prof. Dr. Ş. Erol OKAN Trakya Üniversitesi

Prof. Dr. Oktay SİNANOĞLU Yale Üniversitesi

Prof. Dr. Yani SKARLATOS Boğaziçi Üniversitesi

Prof. Dr. Bilal TANATAR Bilkent Üniversitesi

Prof. Dr. Hasan TATLIPINAR Yıldız Teknik Üniversitesi

Prof. Dr. Mehmet TOMAK Ortadoğu Teknik Üniversitesi

Prof. Dr. İskender YILGÖR Koç Üniversitesi

Prof. Dr. Ersin YURTSEVER Koç Üniversitesi

SEMPOZYUM DÜZENLEME KURULU

Prof. Dr. Zehra AKDENİZ Piri Reis Üniversitesi

Yrd. Doç. Dr. Zeynep ÇİÇEK ÖNEM İstanbul Üniversitesi

Yrd. Doç. Dr. Ali KARAMAN İstanbul Üniversitesi

Yrd. Doç. Dr. Gülşen AKIN EVİNGÜR Piri Reis Üniversitesi

Hanifi ARSLAN Piri Reis Üniversitesi

Sıvıhal Fiziği Çalışma Grubu 15. ULUSAL SIVIHAL FİZİĞİ SEMPOZYUMU

24-25 Kasım 2011

Piri Reis Üniversitesi, Tuzla-İstanbul

PROGRAM

24 Kasım 2011, Perşembe

09.30 – 10.30 Kayıt

10.30 – 11.25 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)

11.30 – 11:40 BREAK / ARA

11.40 – 12.20 Denizin Farklı Kültürleri

Sargun A. Tont (Sabancı Üniversitesi)

12.20 – 12.50 SU: Fiziği, Nanofiziği, Kimyası ve Jeopolitiği

Sondan Feyiz Durukanoğlu (Sabancı Üniversitesi)

12.50 – 13.10 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)

13.15 – 14.10 ÖĞLE YEMEĞİ

13:50 – 14.10 Bistability of a two- mode BEC in an optical cavity

S.Safaei, O.E.Mustecaplioğlu, B.Tanatar

(Bilkent Üniversitesi)

14.10 – 14.40 Computational design of metal borohydrides and metal

ammines for energy storage

Adem Tekin

(İstanbul Teknik Üniversitesi)

14.40 – 15.10 Su Dalgalarının Modellenmesi ve Uygulamaları

Serdar Beji (İstanbul Teknik Üniversitesi)

15.10 – 15.55 Araştırma ve Erişim Odaklı Eğitim

Nihat Berker (Sabancı Üniversitesi)

16.00- SEMPOZYUM KOKTEYLİ

25 Kasım 2011, Cuma

09.40 – 10.00 Stability of spin-orbit coupled Fermi gases with

population imbalance

Levent Subaşı (İstanbul Teknik Üniversitesi)

10.00 – 10.20 Sol-Gel Phase Transitions in Composite Gels

Gülşen Akın Evingür, Önder Pekcan (Piri Reis Üniversitesi)

10.20 – 10.40 Quantum Phase Transitions in Atomic Condensates

Coupled to Driven Dissipative Optical Cavities

Özgür E. Müstecaplıoğlu

(Koç Üniversitesi)

10.40 – 11.00 Dynamical properties of a coupled nonlinear

dielectric waveguide surface-plasmon

josephson junction system

Yasa Ekşioğlu, Özgür E. Müstecaplıoğlu, Kaan Güven

(Koç Üniversitesi)

BREAK / ARA

11.15 – 11.35 Çeşitli metal kümelerinin katı-sıvı faz geçişleri

Meral Eryürek, M. H. Güven (Karaelmas Üniversitesi)

11.35 – 11.55 DFT study of rhenium-doped boron clusters: ReBn

(n=1-15)

Servet Kurt, M. Böyükata, Z. B. Güvenç (Bozok Üniversitesi)

11:55 – 12.05 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)

12.05 – 12.15 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)

12.30 – 13.40 ÖĞLE YEMEĞİ

13.40 – 14.00 Spontaneous Formation of A Nanotube From A

Square Ag Nanowire:

An Atomistic View

Mine Konuk, Sondan Feyiz Durukanoğlu

(İstanbul Teknik Üniversitesi)

14.00 – 14.20 Modifiye Aljinat Jellerinden Protein Salımı

Hakan Kaygusuz, F. Bedia Erim

(İstanbul Teknik Üniversitesi)

14.20 – 14.40 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)

BREAK / ARA

15.00 – 15.20 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)

15.20 – 15.40 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)

15.40 – 16.00 The potential profile of quantum well under the laser

and electric fields

Figen Karaca Boz, Saban Aktas, Şevket Erol

Okan

(Trakya Üniversitesi) 16.00 – 16.30 Denizlerdeki Hazine

Gülaçtı Topçu

(Bezmialem Vakıf Üniversitesi)

Denge,Deniz, Strateji, Rekabet

Dr. Mühendis Ekber Onuk

Yonca Onuk Tersanesi

Denizin Farklı Kültürleri

Sargun A. Tont

Sabancı Üniversitesi

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.

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

ERBİL2

1Piri Reis Üniversitesi, İstanbul, Türkiye

ceozen@yahoo.com 2Gebze 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 enerjisi1, mekanik özellikleri1, ıslanabilirliği2 ve pürüzlülüğü3,4 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 çalışmanın5 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 polipropilen-

polietilen (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), 75-84 (2010).

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 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.

Computational design of metal borohydrides and metal ammines

for energy storage Adem Tekin

Informatics Institute, Istanbul Technical University, 34469 Maslak Istanbul Turkey

By combining several computational methods, the lowest energy crystal structures of Mg(NH3)nCl2 with n=6,2,1, Mg(BH4)2, LiBH4 and NaBH4 were searched. Furthermore, NH3 ab- and desorption mechanisms involved in metalammines were investigated using a combination of DFT and quasi-elastic neutron scattering measurements.

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 Rashba-

type 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.

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.

Araştırma ve Erişim Odaklı Eğitim

Nihat Berker

Sabancı Üniversitesi

Sol- Gel Phase Transitions in Composite Gels

Gülşen Akın Evingür1and Önder Pekcan2

1Piri Reis University, 34940, Tuzla, Istanbul, TURKEY, gulsen.evingur@pirireis.edu.tr

2Kadir 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, 2006.

24(1): p. 83- 90.

[2] G. Akın Evingur, D. Kaya Aktaş Ö. Pekcan, Steady state fluorescence technique

for studying phase transitions in PAAm- PNIPA mixture. Phase Transitions,

2009. 82(1): p. 53-65.

[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, 2010. 17: p. 301-318.

[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.

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:0912.3261 [quant-

ph].

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.

ÇEŞİTLİ METAL KÜMELERİNİN KATI-SIVI FAZ GEÇİŞLERİ

M..ERYUREK, M. H. GUVEN

Zonguldak Karaelmas Üni.Fen-Ed. Fak. Fiz. Böl.,Zonguldak,TÜRKİYE

meryurek@yahoo.com, haluk_guven@yahoo.com

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.

DFT study of rhenium-doped boron clusters: ReBn (n=1-15)

S. KURT

1, M. BÖYÜKATA

1, Z. B. GÜVENÇ

2

1Department of Physics, Bozok University, 66200 Yozgat, Turkey

2Department of Elect. and Comm. Eng., Çankaya University, 06530 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, Ren (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, ReBn (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 Bn clusters and any boron-metal complexes.

Acknowledgment. This work is supported by Bozok University (BAP-I.F.E.F/2011-32)

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, 063201, (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).

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 Özen4

1İstanbul Technical University, Institute of Science and Technology, Nano Science and

Nano Engineering, 34469 İstanbul, Turkey 2Piri Reis University, 34940, Tuzla, Istanbul, Turkey

3İstanbul Technical University, Institute of Science and Technology, Physics

Engineering,

34469Maslak, İstanbul, Turkey 4İstanbul Technical University, Faculty of Sciences and Letters, Physics Engineering

Department,

34469 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 10000 Da

and 150000 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.

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 Özen4

1İstanbul Technical University, Institute of Science and Technology, Physics

Engineering,

34469Maslak, İstanbul, Turkey 2İstanbul Technical University, Institute of Science and Technology, Nano Science and

Nano Engineering, 34469 İstanbul, Turkey 3Piri Reis University, 34940, Tuzla, Istanbul, Turkey

4İstanbul 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.

Spontaneous Formation of A Nanotube From A Square

Ag Nanowire:

An Atomistic View

M. Konuk1, S. Durukanoglu

2, 3

1 Department of Physics, Istanbul Technical University, Maslak, 34469

Istanbul, Turkey 2 Faculty of Engineering and Natural Sciences, Sabanci University, Orhanli,

Tuzla 34950 Istanbul, Turkey 3 Nanotechnology Research and Application Center, Sabanci University,

Orhanli, Tuzla 34950 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.

20132007.

[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, 065501 (2011).

[3] M. I. Baskes, Phys. Rev. B 46, 2727-2742, (1992); B-J Lee., J-H Shim, and M. I. Baskes,

Phys. Rev. B 68, 144112 (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.

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 L10, L11,

L12, and L13 phases, together with vacancy formation energies, bulk modulus and

elastic properties for L12, L13 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.

20132007.

Ground-state configurations of few interacting bosons confined in

two dimensions by anisotropic harmonic potential

A.I. Mese1, P.Capuzzi

2, S.Aktas

1, Z. Akdeniz

3 and S.E.

Okan1

1Department of Physics, Trakya University, 22030 Edirne,

Turkey 2Instituto de F´ısica de Buenos Aires, Consejo Nacional de

Investigaciones Cient´ıficas y T´ecnicas, Argentina 3Piri Reis University, 34940 Tuzla, Istanbul, Turkey

We studied the ground-state configurations of few bosons confined by a two

dimensional anisotropic harmonic potential and K0 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. 39 9153 (1989).

[2] A. I. Mese, P. Capuzzi, Z.Akdeniz, S.E.Okan and M.P. Tosi J.Phys. 20 335222,

2008

[3] A.I.Mese, P.Capuzzi,S.Aktas,Z.Akdeniz and S.E.Okan Phys. Rev.A 84, 043604

(2011)

[4] S. W. S. Apolinario,et al., Phys. Rev. E 72, 046122 2005

[5] M Saint Jean and C Guthmann, J. Phys. Condens. Matter 14, 13653 2002

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

1Department of Physics, Trakya University,22030, Edirne

2Piri Reis University, 34940 Tuzal-İstanbul, Edirne

3Universite de Nice-Sophia Antipolis, Institut non Lineaire de Nice, CNRS, 1361 route

des Lucioles, 06560 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 square-sinc-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 .

The potential profile of quantum well under the laser and electric

fields. Figen Karaca Boz

1 , Saban Aktas,

1* and Sevket Erol Okan

1

1Department 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.

Fig. 1. The potential profile of the DPQW, and DSQW in the z-direction for α0=25Ao under the electric field F=20kV/cm, the dimensions are LA=50Ao and LB=25Ao.

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 α0=25Ao.

The effect of the electric field on the binding energy in DPQW, and DSQW with LA=50Ao and LB=25Ao 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) 073201.

[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) 1278. [11] E. C. Niculescu, N. Eseanu, Superlattices and microstructures 48 (2010) 416.

-150 -100 -50 0 50 100 150

0

50

100

150

200

250

300

DPQW

DSQW

F=20kV/cm

=25A

o

VD(m

eV

)

z(Ao)

0 5 10 15 20 25

7,5

8,0

8,5

9,0

zi=0

EB(m

eV

)

F(kV/cm)

DPQW

DSQW

0=25 A

o

zi(L

A+L

B)/2

zi(L

A+L

B)/2

b