National Centre of Scientific Research "Demokritos", Greece
Solution-processable organic semiconductors based on anthracene as main components of active layers in OLEDs: Design, synthesis and application
Well-defined, low molecular weight amorphous organic materials based on polyaromatic compounds exhibit interesting optical, electronic, and magnetic properties; whereas they can also serve as the basis for developing lithographic materials. Thus, they have been receiving attention for the development of organic devices in the nanoscale with substantially enhanced performance and new functions. Solution processability of such materials is highly desirable, since techniques, such as spin-coating, lower significantly the cost for the fabrication of the devices. Herein, a design strategy and synthesis of solution-processable small molecules, with well-defined monomolecular structures based on anthracene, is presented. Anthracene moieties are combined with other poly-functionalized planar and tetrahedral cores, providing control of physicochemical properties, such as solubility, thermal stability, and Tg. Selected members of this class, provided amorphous homogeneous films which were stable at temperatures up to 150Â°C. These molecules have been, also, evaluated as main components in the active layer of OLEDs, providing very promising results. Self-patterning was also allowed by incorporation of suitable acid-sensitive functional groups and a photoacid generator. These results demonstrate the potential of these materials to be used in the fabrication of patterned structures for OLEDs. A flexible, efficient and cheap methodology, suitable for the preparation of these anthracene-based molecules in large scale is also described, using representative examples.
Veroniki P Vidali(Abstract)
Veroniki P Vidali is an Organic Chemist. She has completed her PhD at Agricultural University of Athens in 2004. She worked as a Post-Doctoral Fellow at Natural Products and Bioorganic Chemistry Laboratory/Institute of Nanoscience and Nanotechnology at NCSR â€œDemokritos\" from 2004 to 2007 and as Scientific Staff from 2007 to 2017, while since 2017 she has been working as a Research Assistant at NCSR â€œDemokritos\". Her main research interests include organic synthesis of bioactive natural products and polyaromatic compounds applied in nanotechnology. She has co-authored 18 peer-reviewed research articles in international journals and one book-chapter
Anna Ryazanova has graduated MIPT in 2018 and has defended her masterâ€™s degree on theoretical study of point defects in diamond. Currently, she continues her study as a PhD student
rn rnThe nitrogen - vacancy complexes (NV complexes) determine the useful properties of nanodiamond fluorescence . Single nitrogen - vacancy defects in diamond consist of a carbon-substituting nitrogen atom (N) and a vacancy (V) located in the neighboring lattice point . In order to use the NV center, it should be located in a nanometer-size diamond particle. In our recent paper , we found that the most stable position of the vacancy in the near-surface layers of the clean surface C(100)-(2Ã—1) is the defect position in the third layer directly under the dimer row of the upper layer, and for the complex defect nitrogen - vacancy is configuration Â«vacancy in the third layer, nitrogen in the fourth layerÂ» . In this study, the energy characteristics of hydrogen chemisorption on the C(100)-(2Ã—1) diamond surface with vacancy defects and nitrogen - vacancy complexes in singlet and triplet states are investigated using quantum chemistry methods using semi-empirical quantum chemical methods on the C195H112 cluster. Modeling of the hydrogenated surface is traditionally used to determine the overall passivation effect . The main conclusion of this study was shown that the most active centers for hydrogen adsorption are atoms of the surface hexagon, formed from the atoms of the upper and the second layers when a vacancy occurs in a third layer. However, the specific values of the energy characteristics depend on the nature and state of the defect.rn
Annenkov Mikhail graduated from MIPT in 2017, currently is studying on PhD in MIPT
Chemical modification of graphene is a promising method aimed at changing its electronic properties and creating on its basis quantum structures. Fluorine, as hydrogen, is an element that converts graphene into a semiconductor material. One of the methods is the fluorination of graphene in aqueous solutions of hydrofluoric acid . The aim of our work was to study the interaction of F-, FHF- ions and their associates with water molecules with monovacancy and divacancy defects in graphene by quantum-chemical modeling. The C96H24 cluster modeling ordered graphene had a hexagonal shape with zigzag edges corresponding to the most stable configuration of the graphene sheet . Our model and approximation  reproduce well the available literature data of the geometry and relative stability of monovacancies on a pure graphene surface, as well as fluorine adsorption on vacancies [4,5].rnAs a result of the investigation, the energy characteristics of the chemisorption of fluorine from the associates of ions with water molecules were determined. It is shown that vacancies influence the chemisorption parameters: the activation energy decreases, the heat of adsorption increases in comparison with the ordered graphene sheet. The dependence of the heat of chemisorption on the degree of coverage by fluorine is studied. The characteristics of the reaction of vacancy defects with F-, FHF- and hydronium ion are compared. The results obtained can be useful for determining the optimum regimes for the synthesis of fluorographene with specified properties under laboratory conditions.rn
Sergey Mikhailovich Afonin is an Associate Professor in the Department of Intellectual Technical Systems at National Research University of Electronic Technology (Moscow Institute of Electronic Technology MIET). He/She has completed his/her Graduation in Electronic Technology at the National Research University of MIET in 1976 and a PhD in Electronic Technology Engineering and Control Systems at MIET in 1982. He/She has an Academic title of Senior Researcher received at MIET in 1991. He/She is an Aspirant at MIET from 1976 to 79, Junior Researcher at MIET from 1979 to 82, Senior Researcher at MIET from 1983 to 93, Associate Professor at MIET since 1993. His/Her contributions include more than 200 scientific papers to professional publication and 16 inventions. He/She is the Recipient of a Silver medal VDNKH Russia and two Bronze medals VDNKH Russia
Sergey Mikhailovich Afonin(Abstract)
The application of the electromagnetoelastic actuator based on the electromagnetoelasticity for the piezoelectric, piezomagnetic, electrostriction, magnetostriction effects is promising in the nanotechnology, the nano-biology, the power engineering, the microelectronics and the adaptive optics equipment. The correcting devices are chosen for providing the high quality of the control systems for the deformation of the piezo actuator. The analytical expressions for the sufficient absolute stability conditions of the system with the hysteresis nonlinearity of the electromagnetoelastic actuators are written using the Yakubovich absolute stability criterion with the condition on the derivative, which is the development of the Popov absolute stability criterion. For the Lyapunov-stable control system, the Yakubovich absolute stability criterion for the systems with the single hysteresis nonlinearity provides the simplest and pictorial representation of results of the investigation of the stability and the possibility of the synthesis of the correcting devices of the system ensuring the stability of the strain control systems with the electromagnetoelastic actuators. The characteristics of the electromagnetoelastic actuators are the alternating-sign hysteresis type for the piezo actuators and the constant-sign butterfly type for the electrostriction actuators. In the magnetostriction and electrostriction actuators their initial operating point is chosen on one wing of the butterfly, for example, in the first quadrant, for the deformation range to be symmetric at both sides of the initial point. For the butterfly characteristic the initial working point displaced by the half deformation range. The values of the tangents of the inclination angles of the tangent line to the hysteresis nonlinearity on the butterfly wing for the electromagnetoelastic actuator are determined similar to the hysteresis characteristic. The stationary set of the control systems is the segment of the straight line. The absolute stability conditions with the condition on the derivative of the control systems with piezo actuator deformation in the case of the longitudinal, transverse and shift piezo effect for the hysteresis characteristic of the deformation of the piezo actuator are obtained. The obtained absolute stability conditions for the control system with the electromagnetoelastic actuator allow one to estimate and calculate the characteristics of the control system for the deformation of the electromagnetoelastic actuator.
Kunsan National University, South Korea
Preparation and fabrication studies of three dimensionally ordered nano-, micro- and meso-scale calcium phosphate crystallites scaffold for artificial bone materials (3-DOMm
Myung Chul Chang has completed his PhD at Seoul National University and Postdoctoral studies at University Illinois at Urbana Champaign. He is the Director of Biomaterials Lab. He has published more than 50 papers in reputed journals and has been serving as an Editorial Board Member of reputed journals
Myung Chul Chang(Abstract)
Preparation and fabrication studies of three dimensionally ordered nano-, micro- and meso-scale calcium phosphate crystallites scaffold for artificial bone materials (3-DOMm): In clinical surgeon for humane bone replacement the artificial bone materials have been developed on a basis of biomechanical capability and nontoxic ability. Since 1987 the calcium phoaphte bone materials have been developed, showing proper mechanical strength, bioability and bone regeneration in bone metabolism. From several years ago global companies such as Stryker, ETEX and Biomet-Merck have commercially introduced the calcium phosphate bone products. The structure of humane bone is known to be the nanocomposites between collagen and hydroxyapatite. Biomimetic bone science have studied for the clinically possible surgical application of calcium phosphate bone. The primary study was how to mimic porous bone scaffold in calcium phosphate/collagen matrix. The second issue was how to attain the mechanical property of real humane bone. In first generation of artificial bone development acrylic polymer such as PMMA was mostly used because of the good mechanical strength in spite of serious toxic problem during surgery. Since calcium phosphate cement [CPC] bone has been introduced as bone regeneration, there was a big problem in clinical application because of low mechanical strength. Polymer modification study into CPC cement has been tried. We have focused on the development of pure calcium phosphate products having proper mechanical strength similar to real humane bone. The bioregeneration ability was shown and new syringe design was introduced for the clinical surgeon. We have been keeping the study of calcium phosphate science and engineering technology in bone metabolic condition. All of phosphate research are based on monodispersed control of nano-, micro-, and meso-scale for the bone scaffold application
Yavar Mansouri is a PhD student at MISiS university and nowadays he working and researching on thermomechanical, coating and magnetostriction property of Fe-Ga materials. He had worked and researched on near-alpha titanium alloys for 3 years. He is familiar with fatigue processes and implementations too.
The aim of this research is to investigate the effects of duplex solution annealing treatment on microstructure and also high and low temperature tensile properties of a near alpha titanium alloy, Ti-6Al-2Sn-4Zr-2Mo, in comparison with single solution annealing treatment. In this regard, the single solution annealing process was carried out for one hour on samples at 955 Â°C, and then continued by aging process for 8 hours at 600 Â°C. After that, the microstructural and mechanical characteristics were investigated. In the following and in order to study around the effects of duplex solution annealing, after the single annealing, the samples experienced second annealing routes as 800 Â°C, 850 Â°C and 900 Â°C for 30 minutes which then followed by aging as above. Note that all specimens were air cooled after each heat treatment. Microstructural investigations revealed that secondary alpha phase thickness in the transformed beta matrix of higher temperatures duplex annealed specimens is more than single annealed ones. Also the volume fraction of primary alpha phase was increased by second annealing. Finally, the results of high and low temperature tensile tests indicated an increase in strength and a decrease in elongation of duplex annealed samples.