Fermi level pinning by integer charge transfer at electrode-organic semiconductor interfaces

The atomic structure of interfaces between conducting electrodes and molecular organic materials varies considerably. Yet experiments show that pinning of the Fermi level, which is observed at such interfaces, does not depend upon the structural details. In this letter, we develop a general model to explain Fermi level pinning, and formulate simple expressions for the pinning levels, based upon integer charge transfer between the conductor and the molecular layer. In particular, we show that DFT calculations give good values for the pinning levels

From spin-polarized interfaces to giant magnetoresistance in organic spin valves

We calculate the spin-polarized electronic transport through a molecular bilayer spin valve from first principles, and establish the link between the magnetoresistance and the spin-dependent interactions at the metal-molecule interfaces. The magnetoresistance of a Fe| bilayer-C 70 | Fe spin valve attains a high value of 70% in the linear-response regime, but it drops sharply as a function of the applied bias. The current polarization has a value of 80% in linear response and also decreases as a function of bias. Both these trends can be modeled in terms of prominent spin-dependent Fe| C 70 interface states close to the Fermi level, unfolding the potential of spinterface science to control and optimize spin current

Silicene-Like Domains on IrSi3 Crystallites

Recently, silicene, the graphene equivalent of silicon, has attracted a lot of attention due to its compatibility with Si-based electronics. So far, silicene has been epitaxy grown on various crystalline surfaces such as Ag(110), Ag(111), Ir(111), ZrB2(0001) and Au(110) substrates. Here, we present a new method to grow silicene via high temperature surface reconstruction of hexagonal IrSi3 nanocrystals. The h-IrSi3 nanocrystals are formed by annealing thin Ir layers on Si(111) surface. A detailed analysis of the STM images shows the formation of silicene like domains on the surface of some of the IrSi3 crystallites. We studied both morphology and electronic properties of these domains by using both scanning tunneling microscopy/spectroscopy and first-principles calculation methods

A versatile and reconfigurable microassembly workstation

In this paper, a versatile and reconfigurable microassembly workstation designed and realized as a research tool for investigation of the problems in microassembly and micromanipulation processes and recent developments on mechanical and control structure of the system with respect to the previous workstation are presented. These developments include: (i) addition of a manipulator system to realize more complicated assembly and manipulation tasks, (ii) addition of extra DOF for the vision system and sample holder stages in order to make the system more versatile (iii) a new optical microscope as the vision system in order to visualize the microworld and determine the position and orientation of micro components to be assembled or manipulated, (iv) a modular control system hardware which allows handling more DOF. In addition several experiments using the workstation are presented in different modes of operation like tele-operated, semiautomated and fully automated by means of visual based schemes

Mikro montaj İş İstasyonu

Bu makalede, mikro boyuttaki komponentlerin verimli ve güvenilir montajı için açık-mimarili, tekrar yapılandırılabilir bir mikromontaj iş istasyonu sunulmaktadır. Bu iş istasyonu mikro dünyadaki problemlerin çözümlendirilmesine yardımcı olmak amacıyla bir araştırma aracı olarak tasarlanmıştır. Böyle bir iş istasyonunun geliştirilmesi aşağıdaki alt sistemlerin tasarımını içermektedir: (i) montaj görevlerininin gerçekleştirilebilmesi için yeterli hareket menzilini ve hassasiyeti sağlayabilecek hareket platformlarından oluşan bir manipülatör sistemi, (ii) mikro dünyanın görselleştirilmesini ve montajı yapılacak olan mikro parçaların konum ve yönelimlerini belirleyebilmek için bir görü sistemi, (iii) dayanıklı bir denetleme sistemi ve bunlara ek olarak manipülasyon araçlarının kolayca değişmesine olanak sağlayan ve sistemin önceden belirlenmiş göreve hazır hale getirilmesine yardımcı olacak uç takımlar için gerekli fikstürler. Ayrıca sistemde kumandalı ve yarı otomatik montaj uygulamaları da gerçekleştirilmiştir. Tasarım mikro parça manipülasyonu içeren çeşitli uygulamalar yapılarak test edilmiştir. İş istasyonunun çok yönlülüğü ve yüksek doğrulukta konumlama yeteneği yapılan deneylerle gösterilmiştir

Çok Yönlü ve Tekrar Yapılandırılabilir Mikro Montaj İş İstasyonu

Bu makalede, mikro montaj ve mikro manipülasyon süreçlerindeki sorunların incelenmesi amacıyla bir araştırma aracı olarak tasarlanan ve geliştirilen çok yönlü ve tekrar yapılandırılabilir mikro montaj iş istasyonu ve yine aynı grup tarafından geliştirilen bir önceki sistem üzerinde mekanik ve denetim yapıları açısından yapılan geliştirmeler sunulmaktadır. Bu geliştirmeler; (i) daha karmaşık montaj ve manipülasyon işlemlerinin gerçekleştirilebilmesi için ek bir manipülatör modülünün eklenmesi, (ii) sistemi daha yetenekli kılabilmek için görü sistemi ve numune taşıyıcı platformlarına ek hareket serbestlik derecesi eklenmesi (iii) mikro dünyanın görüntülenmesi ve montajı yapılacak veya manipüle edilecek parçaların konum ve yönelimlerinin belirlenebilmesi amacıyla görü sistemi olarak yeni bir optik mikroskobun eklenmesi (iv) daha fazla serbestlik derecesinin denetimini sağlayabilmek amacıyla varolan sistemin daha modüler bir denetim sistemi donanımı ile değiştirilmesi gibi unsurları içermektedir. Ayrıca sistemde kumandalı, yarı otomatik ve görü bazlı yöntemler aracılığı ile tamamen otomatik çalışma modlarında yapılan deney sonuçları da sunulmaktadır

New Mediterranean biodiversity records (October 2015)

The Collective Article “New Mediterranean Biodiversity Records” of the Mediterranean Marine Science journal offers the means to publish biodiversity records in the Mediterranean Sea. The current article has adopted a country-based classification and the countries are listed according to their geographic position, from west to east. New biodiversity data are reported for 7 different countries, although one species reported from Malta is new for the entire Mediterranean basin, and is presumably also present in Israel and Lebanon (see below, under Malta). Italy: the rare native fish Gobius kolombatovici is first reported from the Ionian Sea, whilst the alien jellyfish Rhopilema nomadica and the alien fish Oplegnathus fasciatus are first reported from the entire country. The presence of O. fasciatus from Trieste is concomitantly the first for the entire Adriatic Sea. Finally, the alien bivalve Arcuatula senhousia is reported for the first time from Campania (Tyrrhenian Sea). Tunisia: a bloom of the alien crab ortunus segnis is first reported from the Gulf of Gabes, where it was considered as casual. Malta: the alien flatworm Maritigrella fuscopunctata is recorded in the Mediterranean Sea for the first time, on the basis of 25 specimens. At the same time, web searches include possible unpublished records from Israel and Lebanon. The alien crab P. segnis, already mentioned above, is first formally reported from Malta based on specimens collected in 1972. Concomitantly, the presence of Callinectes sapidus in Maltese waters is excluded since based on misidentifications. Greece: the Atlantic northern brown shrimp Penaeus atzecus, previously known from the Ionian Sea from sporadic records only, is now well established in Greek and international Ionian waters. The alien sea urchin Diadema setosum is reported for the second time from Greece, and its first record from the country is backdated to 2010 in Rhodes Island. The alien lionfish Pterois miles is first reported from Greece and concomitantly from the entire Aegean Sea. Turkey: the alien rhodophyte Antithamnion hubbsii is first reported from Turkey and the entire eastern Mediterranean. New distribution data are also provided for the native fishes Alectis alexandrina and Heptranchias perlo. In particular, the former record consists of a juvenile measuring 21.38 mm total length, whilst the latter by a mature male. Cyprus: the rare native cephalopod Macrotritopus defilippi, and the alien crab Atergatis roseus, sea slug Plocamopherus ocellatus and fish Cheilodipterus novemstriatus are first recorded from the entire country. Lebanon: the alien crabs Actaea savignii and Matuta victor, as well as the alien fish Synanceia verrucosa, are first recorded from the entire country. In addition, the first Mediterranean record of A. savignii is backdated to 2006, whilst the high number of M. victor specimens observed in Lebanon suggest its establishment in the Basin. The Atlantic fishes Paranthias furcifer and Seriola fasciata, and the circumtropical Rachycentron canadum, are also first reported from the country. The P. furcifer record backdates its presence in the Mediterranean to 2007, whilst S. fasciata records backdate its presence in the eastern Mediterranean to 2005. Finally, two of these latter species have been recently ascribed to alien species, but all three species may fit the cryptogenic category, if not a new one, better.peer-reviewe