bluuebunny/crossref_metadata_2025_split huggingface dataset:
Persistent Inhibition of Cell Growth on Silver Implanted Glassy Polymeric Carbon
Authors: Zimmerman Robert L. , Gürhan Ismet , Ozdal-Kurt F. , Sen B. H. , Rodrigues Marcello , Ila Daryush 
Published: April 2011

ABSTRACTWe have shown that silver ion implantation or argon ion assisted surface deposition of silver inhibits cell growth on Glassy Polymeric Carbon (GPC), a desirable improvement of current cardiac implants. In vitro biocompatibility tests have been carried out with model cell lines to demonstrate that near surface implantation of silver in GPC can completely inhibit cell attachment on implanted areas while leaving adjacent areas vulnerable to strong cell adhesion. After cleaning and sterilization and more than one year in physiologic solution, the silver implanted GPC persists in inhibiting cell attachment.
Osteogenic differentiation of ES cell-derived EBs mediated by embedded BMP-2 and TGF-beta-1 in a polyelectrolyte multilayer film
Authors: Hajare Mjahed , Delphine Cortial , Youssef Haikel , Andree Dierich , Jean-Claude Voegel , nadia Benkirane Jessel 
Published: April 2011

ABSTRACTIn recent years, considerable effort has been devoted to the design and controlled fabrication of structured materials with functional properties. The layer by layer buildup of polyelectrolyte multilayer films (PEM films) from oppositely charged polyelectrolytes1 offers new opportunities for the preparation of functionalized biomaterial coatings. This technique allows the preparation of supramolecular nano-architectures exhibiting specific properties in terms of control of cell activation and may also play a role in the development of local drug delivery systems. Peptides, proteins or DNA, chemically bound to polyelectrolytes, adsorbed or embedded in PEM films, have been shown to retain their biological activities. Recently, tissue engineering has merged with stem cell technology with interest to develop new sources of transplantable material for injury or disease treatment. Eminently interesting, are bone and joint injuries disorders because of the low self-regenerating capacity of the matrix secreting cells. We present here for the first time that embedded BMP-2 and TGFβ1 in a multilayered polyelectrolyte film can drive embryonic stem cells to the cartilage or bone differentiation depending on supplementary co-factors. We selected a model system made from layer by layer poly-ℓ-glutamic acid (PℓGA) and poly-ℓ-lysine succinylated (PℓLs) films into which BMP-2 and TGFβ1 have been embedded. Our results demonstrate clearly that we are able to induce osteogenesis in embryonic stem cells mediated by growth factors embedded in a polyelectrolyte multilayer film.
Evaluation of Biological Responses of UMR-106 Cells to Porous PHBV Matrix
Authors: Raghavan Dharmaraj , Liu Hui , Stubbs John 
Published: April 2011

ABSTRACTThis paper compared the results of osteoblast-like UMR-106 cells response to 3-D biodegradable porous with nonporous PHBV (poly (3-hydroxybutyrate-co-3-hydroxyvalerate) films. Nonporous PHBV films were prepared by solvent casting and evaporation. Porous PHBV films were prepared by solute leaching of salt/PHBV cast film. Sieved sodium chloride (∼150 μm) was used to create a matrix with high porosity and then leached out by the solvent. Thermo gravimetric analysis showed that over 99% of the salts were leached out by the solvent. Osteoblast-like UMR-106 cells were seeded onto the nonporous and porous PHBV films, respectively. After 6 and 10 days of incubation, growth rate of UMR-106 cells on porous film was higher than on nonporous film. The viable cell proliferation on the porous and nonporous PHBV film was quantified by (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt) (MTS) assay. The results of this study suggest that the UMR-106 cells proliferate more on the porous PHBV matrix and porous PHBV films are a promising material for bone tissue engineering applications.
Photoluminescence Excitation Dependence in Three-dimensional Si/SiGe Nanostructures
Authors: Lee Eun-Kyu , Kamenev Boris V. , Kamins Theodore I. , Baribeau Jean-Marc , Lockwood David J. , Tsybeskov Leonid 
Published: April 2011

ABSTRACTWe find that in SiGe clusters grown on Si using Stranski-Krastanov (S-K) growth mode, (i) photoluminescence (PL) spectra, (ii) PL lifetime and (iii) PL thermal quench activation energies exhibit strong dependence on the excitation intensity. Under PL excitation intensity increasing from 1 to 104 W/cm2, the PL spectra exhibit blue shift from below Ge bandgap up to ∼970 meV. The PL lifetime shows strong dependence on the excitation wavelength, decreasing from 20 μs at ∼0.8 eV to 200 ns at ∼ 0.9 eV. The process of PL thermal quench has two clearly distinguished activation energies. At low temperature, small (∼15 meV) and excitation-independent activation energy is attributed to exciton thermal dissociation. At higher temperature, excitation-dependent PL thermal quench activation energy (increasing from ∼ 120 to 340 meV as excitation intensity increases) is found, and it is attributed to hole redistribution via tunneling and/or thermal ionization over the Si/SiGe valence band energy barrier.
Nitrogen Influence on the Photoluminescence Properties of Silicon Nanocrystals
Authors: Ferraioli Luigi , Bellutti Pierluigi , Daldosso Nicola , Mulloni Viviana , Pavesi Lorenzo 
Published: April 2011

ABSTRACTWe have performed photoluminescence analysis of silicon rich oxide (SRO) and silicon rich oxynitride (SRON) samples deposited by plasma enhanced chemical vapor deposition (PECVD) and thermally annealed to cause the formation of silicon nanocrystals (Si-nc). Our purpose was to investigate the influence of nitrogen embedded into the oxide matrix on the photoluminescence properties of Si-nc. We found a large incorporation of silicon and a decrease of its diffusivity when the oxide is nitrogen rich. As a consequence the rate of crystallization for Si aggregates is slowed down when nitrogen is present in the oxide matrix.
Time Evolution of Nano-scale Morphology of Silicon Microstructure Surfaces in the Early Phase of Hydrogen Annealing
Authors: Hiruta Reiko , Kuribayashi Hitoshi , Shimizu Ryosuke , Sudoh Koichi , Iwasaki Hiroshi 
Published: April 2011

ABSTRACTWe have examined how the morphology of the trench sidewall evolves in the early phase of hydrogen annealing under the two conditions of hydrogen pressures. A distinguished result was obtained concerning the sidewall surface morphology after 30 s annealing at 1000 °C under 760 Torr hydrogen ambient. The evanescence of chemical Si dioxide formed by RCA cleaning process was clearly observed to initiate in various places on the surface. And in the area without chemical oxide, the appearance of atomic steps was also observed. In contrast under 40 Torr hydrogen ambient, the chemical oxide was completely removed even after 30 s annealing. Our observation shows that not only the rate of trench shape transformation but also the rate of removal of oxide films decreases with increasing hydrogen pressure.
Junctions of Carbon Nanotubes and Silicon Nanowires Synthesized by ethanol-Co Chemical Vapor Deposition
Authors: Yoshida Hideto , Uchiyama Tetsuya , Kikkawa Jun , Takeda Seiji , Homma Yoshikazu 
Published: April 2011

ABSTRACTCarbon nanotubes (CNTs) have been grown on silicon nanowires (SiNWs) by chemical vapor deposition using Co catalyst nanoparticles. Single-walled CNTs have been grown mainly when a thin Co film (0.1 nm thick) was deposited on SiNWs, while both SWNTs and MWNTs have been grown on SiNWs on which Co 0.5 nm thick was deposited. The correlation between the diameter of catalyst nanoparticles and that of CNTs has been investigated by transmission electron microscopy. The average diameter of CNTs is smaller than that of catalyst nanoparticles.
High Yield Growth of Various CdS Nano-Structures and Their Electron Field Emission Behavior
Authors: Lawrance Juno , Gutu Timothy , McClain Devon , Wu Jianfeng , Jiao Jun 
Published: April 2011

ABSTRACTNanostructures are considered the critical component in a wide range of potential nanoscale device applications. Yet a procedure to fabricate them with both controllable results and in bulk quantities must be developed in order to achieve their commercialization at reduced cost. In this report, we introduce an improved vapor-liquid-solid method that is capable of preparing high yield, high quality CdS nanowires and nanobelts in a turf-like configuration. To increase yield, we placed gold-coated substrates in a ceramic boat partially covered with a glass slide to form a gas trap. Only a small opening was provided to allow the CdS vapor to escape from the trap. This arrangement increases catalyst exposure to CdS vapor flow in comparison to conventional CVD methods. This allowed the CdS vapor to deposit densely over the substrate at a predetermined temperature range of 501°C-630°C inside the quartz tube. These conditions results in synthesis of various morphologies on both quartz and tungsten substrates including an intertwined-like structure not previously reported. Electron microscopy and microanalysis techniques were utilized in characterizing these morphologies, internal structures and elemental compositions. Electron field emission properties were investigated in an ultra high vacuum chamber set up with a base pressure of ∼1E-9 torr.
Electronic and Mechanical Properties of Super Carbon Nanotube Networks
Authors: Coluci Vitor R. , Dantas Socrates O. , Jorio Ado , Galvao Douglas s 
Published: April 2011

ABSTRACTEletronic and mechanical properties of ordered carbon nanotube networks are studied using molecular dynamics simulations and tight-binding calculations. These networks are formed by single walled carbon nanotubes (SWNT) regularly connected by junctions. The use of different types of junctions (“Y”-, “X”-like junctions, for example) allows the construction of networks with different symmetries. These networks can be very flexible and the elastic deformation was associated with two main deformation mechanisms (bending and stretching ) of the constituents SWNTs. Rolling up the networks, “super” carbon nanotubes can be constructed. These super-tubes share some of the main electronic features of the SWNT which form them but important changes are predicted (e.g. reduction of bandgap value). Simulations of their deformations under tensile stress have revealed that the super-tubes are softer than the corresponding SWNT and that their rupture occur in higher strain values.
Novel Organic Light-Emitting Transistors with PN-Hetero-Boundary Carrier Recombination Sites Fabricated by Lift-off Patterning of Organic Semiconductor Thin Films
Authors: Suganuma Naotoshi , Shimoji Noriyuki , Oku Yoshiaki , Matsushige Kazumi 
Published: April 2011

ABSTRACTWe have devised a novel organic light-emitting transistor (OLET) with PN-hetero-boundary combined with hole and electron transport materials along carrier channels. In this device, a clear modulation of the current and luminance with the gate voltage is observed. The luminance of 100 cd/m2 or more has been observed at the source-source voltage of 15 V with the turn-on voltage of 10 V or less, which is lower than that of OLETs based on a single organic material. We have implemented the horizontal PN-hetero-boundary structure for the first time by using the photolithographic patterning of the organic semiconductor thin-films. This patterning technique can be applied to fabrication of not only organic light-emitting transistors we report in this paper but also organic integrated circuits or organic displays.
Bottom Contact Ambipolar Organic Thin Film Transistors Based on C60/Pentacene Heterostructure
Authors: Kanai Kaname , Wang Suidong , Seki Kazuhiko 
Published: April 2011

ABSTRACTWe report the fabrication and characterization of the bottom contact organic thin film transistors and inverter based on a heterostructure of C60 on pentacene. The transistor shows ambipolar transport characteristics with high electron and hole mobilities of 0.23 cm2V−1s−1 and 0.14 cm2V−1s−1, respectively. After exposure to air, the n-channel in C60 is completely degraded whereas the p-channel in pentacene keeps working. Both the n-channel and the p-channel are stable in N2 atmosphere. The inverter exhibits typical transfer characteristics, which are interpreted by the distribution of the accumulated electrons and holes depending on the bias conditions. These results suggest a potential way to fabricate organic complementary circuits with a single organic heterostructure device.
Fabrication of Ion-Paths for Ionic Liquid Type Quasi-Solid Dye Sensitized Solar Cell
Authors: Kado Takashi , Kato Takehito , kogo Takeshi , Inakazu Fumi , Noma Yusuke , Ogomi Yuhei , Yamaguchi Yoshihiro , Kohno Mitsuru , Hayase Shuzi 
Published: April 2011

ABSTRACTA direction to increasing photovoltaic performances of dye sensitized solar cells (DSC) is proposed. An interface between TiO2/dye and an electrolyte layer is focused on. It is proved that better coverage of TiO2layers with dye molecules increases photovoltaic performances, where dye staining is carried out in pressurized CO2atmosphere. This is explained by decreases in the amount of surface traps on TiO2nano-particles, which is discussed by thermally stimulated current (TSC). The decrease in the surface trap density increases electron diffusion coefficient and improves electron lifetime in TiO2layers. In addition, the TiO2-staining with dye molecules having the larger dipole moment seems to leave less amount of electron trap. Another crucial research item is solidification. Quasi-solidification is carried out by using surface modified anodically-oxidized Al2O3films filled with ionic liquids, where ion paths are fabricated on the surface-modified Al2O3walls by concentrating iodine and iodide molecules on the walls. Because of the fabrication of the ion path, photovoltaic performances increased even after solidification. Grötthuss type mechanism is introduced to explain the increase in the photovoltaic performances after the solidification.
Microfluidic Devices for Novel Synthesis
Authors: Choi Kyung 
Published: April 2011

ABSTRACTWe demonstrate here functional polymeric particle synthesis by employing a microfluidic approach. The functional polymer is MIP system (molecularly imprinted polymer), which can be produced by “molecular imprinting”, a general protocol for the preparation of “synthetic receptor or binding sites” with specific recognition for targeted organic molecules. The recognition of complex molecules and biological entities is a necessary component for fabricating chemical sensors, diagonostic bio-sensors, and for drug delivery systems. We have obtained homogeneous MIP's microparticles, which may have high affinity receptor sites only by fabricating a microreactor.
Effect of Buffer or Barrier Layer on Bistability for Nonvolatile Memory Fabricated with Al Nanocrystals Embedded in α-NPD
Authors: Seo Sung-ho , Nam Woo-sik , Kim Jae-seok , Shin Chang-hyup , Lim Se-yun , Park Jea-gun , Kim Yoon-joong 
Published: April 2011

ABSTRACTRecently, low molecular organic non-volatile memories have been developed as a next generation of non-volatile memory because of nano-meter device-feature size and nano-second access and store-time. We developed a non-volatile memory fabricated with the device structure of Al/ α-NPD/Al nano-crystals surrounded by Al2O3/α-NPD/Al, where α-NPD is N,N'-bis(1-naphthyl)-1,1'biphenyl4-4”diamine. One layer of Al nano-crystals with ∼20 nm-width ∼20 nm length was uniform produced between α-NPD layers, confirmed by 1.2MV high voltage transmission-electron-microscope. This device showed Vth of 3.0 V, Vprogram of 4.3 V, and Verase of 6.3 V. Particularly, this device exhibited an excellent non-volatile memory behavior performing the bi-stability (Iprogrm/Ierase) of >1×102, program/erase cycles of >1×105 and multi-levels. In addition, previous reports about low molecular organic non-volatile memories have showed a bad reproducible memory characteristic. However, this issue was completely solved via isolating Al nano-crystals embedded in α-NPD by O2 plasma oxidation. The uniformity of Vth, Vp, and Ve were 9.91%, 6.94% and 7.92%, respectively. Furthermore, the effect of buffer or barrier layer on non-volatile memory characteristics was investigate to examine the control ability for Vth, Vp, and Ve. The 0.5-nm LiF showed a barrier layer behavior suppressing the bi-stability of non-volatile memory. Otherwise, 15-nm CuPc exhibited a buffer layer behavior enhancing the bi-stability of nonvolatile memory.
Effect of Structural Phase Transition on Thermally Activated Time-of-Flight Charge Carrier Mobility and Field Effect Transport in Diindenoperylene Single Crystals
Authors: Tripathi Ashutosh Kumar , Pflaum Jens 
Published: April 2011

ABSTRACTWe report on the growth, the structural and the electronic characterization of semiconducting Diindenoperylene (DIP) single crystals. Temperature dependent x-ray measurements reveal a structural phase transition occurring at around 370 K. Temperature dependent time-of-flight (TOF) hole mobility shows a thermally activated behavior up to the phase transition temperature with an activation energy of ∼ 180 meV. A field effect is successfully demonstrated on transistors based on DIP single crystal and yields a room temperature hole mobility of about ∼ 2×10−5 cm2/Vs. Unlike TOF measurements, no electron transport was observed in field-effect transistors (FETs) geometry which could be attributed to the large injection barrier for electrons at the DIP-Ag-contact interface in contrast to the injection barrier for holes.
Development of Flexible Photo Sensor and Memory Devices Based on Organic Photo FET
Authors: Yoshida Manabu , Kawai Hiroki , Kondoh Takeshi , Kawai Takeshi , Suemori Kouji , Uemura Sei , Hoshino Satoshi , Kodzasa Takehito , Kamata Toshihide 
Published: April 2011

ABSTRACTThe photo FET having a photosensitive insulator layer showed excellent photo-switching properties upon illuminating the gate dielectric layer, because the gate capacitor was rapidly charged up by providing a large amount of photo-generated charges in the dielectric layer to the gate capacitor. In this study, we have tried to give a memory function to the photo FET. Further, we have tried to fabricate flexible photo FETs by using only solution processes in order to utilize the photo FET as flexible photo sensor and photo memory devices. As a result, we have succeeded in observing the memory effect of the photo FET and the photo-switching behavior of the flexible photo FETs
Optically Transparent Conducting Polymers from Fused Heterocycles
Authors: Yavuz Mustafa Selman , Kumar Arvind , Lee Byoungchul , Bokria Jayesh G. , Dey Tanmoy , Seshadri Venkataramanan , Ner Yogesh , Buyukmumcu Zeki , Sotzing Gregory A. 
Published: April 2011

ABSTRACTResearch in the field of optically transparent conducting polymers has been gaining great attention due to their relatively low processing cost, light weight and flexibility as compared to their inorganic counterpart. Besides having found several applications in the field of electronic and optoelectronic devices, optically transparent conducting polymers are primarily used as a hole- injection layers in photovoltaics and light-emitting devices. Herein, we report the electronic and optoelectronic properties of conducting polymers obtained from different fused heterocycles, viz. thieno[3,4-b]furan, thieno[3,4-b]thiophene, and dimers of thieno[3,4-b]thiophene. Aqueous dispersion polymerization in the presence of poly(styrene sulfonic acid) as a template is also performed to make them processable from water. Water soluble conducting polymer was obtained via ring sulfonation of chemically or electrochemically prepared polythieno[3,4-b]thiophene [PT34bT]. The optical properties were tuned by varying sulfonation level or by depositing different number of bilayers via layer-by-layer technique. Stable conjugated polymers with band gaps ranging from 0.8 to 1.6 eV were obtained.
Transition from Non-Dispersive to Dispersive Hole Transport in a Small Molecule Organic Semiconductor Controlled by Molecular Doping
Authors: Fleissner Arne , Schmid Hanna , Melzer Christian , Schmechel Roland , von Seggern Heinz 
Published: April 2011

ABSTRACTThe influence of charge carrier traps on charge carrier transport is studied in a small molecule organic semiconductor model system by means of an optical time-of-flight method. The model system consists of the hole transport material N,N'-di(1-naphtyl)-N,N'-diphenylbenzidine (α-NPD, sometimes denoted as α-NPB) either undoped or doped with various concentrations of the small molecule 4,4',4”-tris-[N-(1-naphtyl)-N-(phenylamino)]-triphenylamine (1-NaphDATA), which is known to create hole traps in α-NPD.In case of undoped α-NPD, non-dispersive hole transport is observed and the hole mobility is determined as 6·10−4cm2/Vs in the examined electric field range, being in good agreement with published data. Depending on the intensity of the laser light employed for optical charge carrier generation, current transients both in the space-charge regime and in the small signal case are obtained. In the small signal case the current transients do not exhibit the expected flat current plateau before the characteristic kink that marks the transit time, but feature a cusp instead. A tentative mechanism for its formation is proposed.The influence of the trap concentration on charge carrier transport is studied by introducing 1-NaphDATA as a molecular dopant. It is demonstrated that the hole transport in α-NPD can be controlled by varying the doping concentration of 1-NaphDATA. Increasing the trap concentration, a transition from non-dispersive transport in undoped α-NPD to non-dispersive but trap-controlled transport with reduced mobility and further to dispersive transport is observed.
Process Optimization of UV Curing for Ultra Low-k Dielectrics and High-Stress SiN Liners
Authors: Matsuura Masazumi , Goto Kinya , Hashii Shinobu , Miura Noriko , Miyagawa Yoshihiro , Murata Tatsunori , Tsunemine Yoshikazu , Asai Koyu 
Published: April 2011

ABSTRACTThis paper describes process optimization of UV curing for ultra Low-k SiOC (ULK-SiOC, k=2.65) and High stress silicon nitride (HS-SiN) liner. We have investigated the impact of UV curing using different UV bulbs (UV-X and UV-Y) on BEOL process damages to the ULK-SiOC. The k-value variations of ULK-SiOC modified with UV-X with higher photon energy than UV-Y are greater than those of the pristine ULK-SiOC and the ULK-SiOC modified with UV-Y. These results are consistent with the previously reported FT-IR and NMR analyses that the UV-X generates 3-fold Si-O ring defects and Si-H bonds in the ULK-SiOC. In order to discuss the pore structure in UV-modified ULK-SiOC, the solvent diffusion of toluene and ethanol in ULK-SiOC were measured. The solvent diffusion of the UV-modified ULK-SiOC with UV-X is faster than that of the UV-modified ULK-SiOC with UV-Y. This result indicates that the pore size of UV-modified ULK-SiOC with UV-X is larger than that of UV- modified ULK-SiOC with UV-Y. The dependence of the stress increase in HS-SiN liner on different UV bulbs (UV-X and UV-Y) has been investigated by using stress measurement and FT-IR. The UV-modified HS-SiN liner with UV-Y achieves higher tensile stress, compared to the UV-X. FT-IR results have revealed that UV-Y is more effective for the dehydrogenation and SiN crosslinking, resulting in the greater increase in the tensile stress. In conclusion, UV-Y bulb with medium photon energy yields the desired UV modifications for ULK-SiOC and HS-SiN applications.