bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interfaces Involving Biomolecules and Inorganic Materials: a Solid State NMR Approach
Authors: Bonhomme Christian , Hartmeyer Geoffrey , Babonneau Florence , Wong Chi Man Michel , Arrachart Guilhem , Carcel Carole , Moreau Joel , Alonso Bruno 
Published: April 2011

AbstractMaterials based on ureidopyrimidinone (UPY) dimers and Adenine (A) / Thymine (T) derivatives were synthesized and characterized by advanced solid state NMR (Nuclear Magnetic Resonance) techniques. Silylated UPY molecules were used as model compounds, leading to structured organic-inorganic materials after hydrolysis and condensation processes (sol-gel reactions). High resolution 1H solid state NMR has been extensively used for the in-depth description of the H-bond networks, including very fast MAS (Magic Angle Spinning) experiments at very high field and DQ (double quantum) recoupling experiments. The chemical nature of the organic-inorganic interface has been illuminated by such techniques. In, particular, it has been demonstrated that H-bond networks were preserved during sol-gel reactions and were comparable to those observed in the UPY crystalline precursors.
Advances in Encapsulating Elastically Stretchable Microelectrode Arrays
Authors: Graudejus Oliver , Tsay Candice , Wagner Sigurd , Yu Zhe , Morrison Barclay , Lacour Stephanie 
Published: April 2011

AbstractStretchable microelectrode arrays (SMEAs) that are fabricated on the compliant silicone poly dimethyl siloxane (PDMS) have potential applications for research on traumatic brain injury (TBI). Increasing the number of electrodes in the array improves the accuracy in assessing the effects of traumatic injury to cell tissue cultures. The currently available encapsulation process with a photopatternable silicone limits the electrode density on the array. The present research examines four factors in the encapsulation process: exposure dose, scattered and reflected light as well as hard bake time. Careful optimization of these four factors leads to a significant reduction of the minimum feature size of a contact via patterned into the encapsulation layer, thus enabling an increase of the electrode density on the array.
Neuro-Technical Interfaces Based on Biocompatible Polymeric Substrates
Authors: Stieglitz Thomas 
Published: April 2011

AbstractMultielectrode arrays create the interfaces between nerves and technical systems in neuroprosthetic devices. MEMS (microelectromechanical systems) technologies offer opportunities to develop high density arrays with large numbers of electrodes and smallest dimensions of electrode site area and pitch. Polymers are promising candidates for flexible substrates of these electrode arrays to meet the requirements of structural biocompatibility. In addition, these substrates must be biostable and should be non-toxic. From an engineering point of view, material processing should be feasible with standard MEMS process technology. Fail-safe integration of electronic circuitry, encapsulation of the systems with substrate-integrated electrodes and connection to cables and connectors is of great importance for reliable (micro-) implants.A comprehensive overview of the application of polymers like silicone rubber, polyimide, and parylene C as substrate, insulation and encapsulation material for multielectrode arrays will be given. Assembling techniques for system integration and encapsulation concepts will be discussed with a special attention on the adhesion properties between substrate, interconnects and insulation and possible failure mechanisms. Application scenarios include peripheral nerve interfaces like cuff and sieve electrodes as well as multielectrode arrays for retinal vision prostheses and shaft and grid arrays for the central nervous system interfaces.
Metallization Process for Polydimethylsiloxane (PDMS) Rubber
Authors: Béfahy Stéphane , Yunus Sami , Burguet Véronique , Heine Jean-Sébastien , Dague Etienne , Trooters Michel , Bertrand Patrick 
Published: April 2011

AbstractA process to fabricate stretchable and adherent gold tracks on flat silicone rubber substrates is studied by X-ray photoelectron spectroscopy (XPS), static water contact angle measurement, atomic force microscopy (AFM) and scanning electron microscopy (SEM). The process involves several steps: curing flat silicone substrate; removing uncured oligomers by hexane Soxhlet extraction; pre-stretching the substrate; activating the strained silicone surface by an oxygen plasma treatment; coating the strained substrate with 5nm titanium and 80nm gold layers by e-beam evaporation; and finally releasing the sample. The plasma treatment creates a thin brittle silica-like layer that temporarily increases the substrate's surface energy. Indeed the plasma treatment is followed by a hydrophobic recovery. As a consequence, the delay between plasma treatment and metal deposition has to be reduced as much as possible. The silica-like layer can be nicely observed after release. Its thickness is estimated to be around 20nm to 50nm. The entire process allows us to obtain stretchable metallized samples that remain conductive even after an excessive deformation leading to electrical failure.
Highly Efficient Detector of the Neurotransmitter ACh and AChE Inhibitors
Authors: Goykhman Ilya , Korbakov Nina , Bartic Carmen , Borghs Gustaaf , Spira Micha E. , Shappir Josef , Yitzchaik Shlomo 
Published: April 2011

AbstractAmong the variety of applications for biosensorsone of the exciting frontiers is to utilize those devices as post-synaptic sensing elements in chemical coupling between neurons and solid-state systems. The first necessary step to attain this challenge is to realize highly efficient detector for neurotransmitter acetylcholine (ACh). Herein, we demonstrate that the combination of floating gate configuration of ion-sensitive field effect transistor (ISFET) together with diluted covalent anchoring of enzyme acetylcholinesterase (AChE) onto device sensing area reveals a remarkable improvement of a four orders of magnitude in dose response to ACh. This high range sensitivity in addition to the benefits of peculiar microelectronic design show, that the presented hybrid provides a competent platform for assembly of artificial chemical synapse junction. Furthermore, our system exhibits clear response to eserine, a competitive inhibitor of AChE, and therefore it can be implemented as an effective sensor of pharmacological reagents, organophosphates, and nerve gases as well.
Hydrogel Based Composite Materials for Chemical, Biological and Medical Sensing Applications
Authors: Porter Timothy L. , Vail Tim , Reed Jim , Stewart Ray 
Published: April 2011

AbstractEmbedded piezoresistive microcantilever (EPM) sensors provide a tiny, low-cost, and robust platform for the detection of chemical or biological analytes. New sensing applications become potentially available as the design or synthesis of new sensing materials for EPM instruments are studies. In this study, we report on the detection of hydrogen fluoride gas (HF) in air, and in a medical application, the measurement of human hydration levels. Two sensing materials characterize these applications, thiolated gold nanoparticles in a keratin matrix (HF), and a crosslinked PVA-based hydrogel in the hydration application.
Light-Matter Interaction of Strong Laser Pulses in the Micro-, Nano-, and Pico-second Regimes
Authors: Agren Hans , Welinder Pontus , Erlandsson Robert , Henriksson Johan , Norman Patrick , Ågren Hans 
Published: April 2011

AbstractLight propagation in a medium is sensitively dependent on the shape and intensity of the optical pulse as well as on the electronic and vibrational structure of the basic molecular units. We review in this paper results of systematic studies of this problem for isotropic media. Our theoretical approach|the quantum mechanical{electrodynamical (QMED) approach is based on a quantum mechanical account of the many-level electron-nuclear medium coupled to a numerical solution of the density matrix and Maxwell's equations. This allows to accommodate a variety of nonlinear e ects which accomplish the propagation of strong light pulses. Particular attention is paid to the understanding of the role of coherent and sequential excitations of electron-nuclear degrees of freedom. The QMED combination of quantum chemistry with classical pulse propagation allows to estimate the optical transmission from cross sections of multi-photon absorption processes and from considerations of propagation e ects, saturation and pulse e ects. Results of the theory suggest that in the nonlinear regime it is often necessary to account simultaneously for coherent one-step and incoherent step-wise multi-photon absorption, as well as for o -resonant excitations even when resonance conditions prevail. The dynamic theory of nonlinear propagation of a few interacting intense light pulses is here highlighted in a study of the optical power limiting with platinum-organic molecular compounds.
Influence of TiO2 on Second Harmonic Generation in Disperse Red -1 doped Organic-Inorganic Hybrid Thin Films
Authors: Zha Congji , Luo Xinshi , Samoc Anna , Rode Andrei , Luther-Davies Barry 
Published: April 2011

AbstractDisperse Red 1 (DR1) doped TiO2-SiO2 inorganic-organic hybrid polymers were prepared by an anhydrous sol-gel process and second harmonic generation (SHG) of the fundamental 1053nm in these polymeric thin films was measured using Maker-fringe method. The nonlinear optical activity of DR1 in the thin films was studied by corona poling at different temperature (from room temperature to 140°C), and the stability of SHG after switching off corona power was evaluated by analyzing the SHG decay dynamics. Experimental results showed that the stability of the SHG of DR1 significantly increases with the cross-linkage degree of the TiO2SiO2 hybrid polymer network, and that the second harmonic coefficient d33 increases as the DR1 concentration increases. TiO2-doping can promote the polymerization of unsaturated C=C double bonds in the hybrid thin films during in-situ hot poling, enhancing the cross-linkage of the network of the hybrid material, and resulting in a great improvement of the stability of SHG. The excellent stability of second harmonic generation in the hybrid polymer thin films suggests that TiO2-doped inorganic-organic hybrid polymer is promising for chromophore doping for nonlinear optical applications.
Excitation of Coherent Phonons in Crystalline Bi: Theory for Driving Atomic Vibrations by Femtosecond Pulses
Authors: Boschetto Davide , Gamaly Eugene G. , Rode Andrei V. , Garl Thomas , Rousse Antoine 
Published: April 2011

AbstractIn this paper we show time-resolved experiment with 35 fs resolution on bismuth single crystal, for which very high sensitivity detection system has been used. Coherent and incoherent lattice dynamics as well as electrons dynamics can be clearly seen into the reflectivity changes. The complex behaviour of the reflectivity could not be explained in the light of the existing theories. Therefore, we developed a new theory, starting from the very basic principle of laser-matter interaction, which is in good agreement with experimental results. Two main results will be shown: the coherent phonon is excited by the temperature gradient; the changes in reflectivity are related directly to the changes in electron-phonon collision frequency.
A Simple Phenomenological Model for Growth of Nanodots with “Magical Sizes” Stabilized by Quantum Size Effect
Authors: Ristolainen Heikki Juha Tapani , Koponen Ismo 
Published: April 2011

AbstractIn deposition of Pb atoms on Cu(111) or Si(111) surface growth of tower-shaped nanostructures is observed. This nanotower growth is caused by structure height dependent energetics, resulting from the quantum size effects (QSE) due to the vertical electron confinement in nanotowers. In this report we present a “wedding cake” -type phenomenological model describing the time evolution of nanostructures. The model reproduces the typical morphologies of nanotowers. The results demonstrate that nanohuts are formed by downward mass currents, due to the downward diffusion of adatoms. Also the stable layers due to the quantum size effects (QSE) can be modelled with a suitable choice of model parameters. In the case of altering stabilities of layers, simultaneous bi-layer growth takes place. The results are in agreement with experimental observations.
Sol-Gel Derived SnO2 Nanometric Fibers
Authors: Saal Kristjan , Tätte Tanel , Paalo Madis , Talviste Rasmus , Vlassov Sergei , Kink Ilmar 
Published: April 2011

AbstractThe applicability of Sn(OBu)4 based viscous oligomeric concentrates in fabrication of thin oxide fibers and needles is demonstrated. Influence of several crucial parameters like viscosity of the concentrate, humidity of surrounding atmosphere and pulling speed on formation of the structures is discussed. We show that the method enables to obtain fibers less than a micron in diameter and needles with tip radii down to 15 nm, i.e. in range that is of considerable interest for many nanotechnological applications.
Electron-Beam Induced Growth of Silica Nanowires and Silica/Carbon Heterostructures
Authors: Solá Francisco , Resto Oscar , Biaggi-Labiosa Azlin M , Fonseca Luis F 
Published: April 2011

AbstractA novel synthesis of silica nanowires and silica/carbon heterostructures by electron beam irradiation on porous silicon films was investigated. The method allows us to monitor the growth process in real time at atomic scales. Depending on the electron dose we obtain nanowires with diameters in the range of 15-49nm and lengths up to 500 nm. We found that the adequate electron dose was between 0.01 Acm-2 and 2 Acm-2. Additional electron dose causes plastic and failure deformations in the silica nanowires. A growth model consistent with our findings is presented that involves the flow of mass from the substrate to the nanowire driven by the local electric fields. Heterostructures showing a nanopalm-like shape are obtained after exposing the silica nanowire to poor vacuum conditions in which carbon aggregation from the surrounding gas is promoted by the local electric fields enhanced at the tip of the silica wires.
In Situ Investigation of the Silver-CTAB System
Authors: Gray Jeremy , Orme Christine , Du Danxu , Srolovitz David 
Published: April 2011

AbstractRecent research has shown that biologically inspired approaches to materials synthesis and self-assembly, hold promise of unprecedented atomic level control of structure and interfaces. In particular, the use of organic molecules to control the production of inorganic technological materials has the potential for controlling grain structure to enhance material strength; controlling facet expression for enhanced catalytic activity; and controlling the shape of nanostructured materials to optimize optical, electrical and magnetic properties. In this work, we use organic molecules to modify silver crystal shapes towards understanding the metal-organic interactions that lead to nanoparticle shape control.Using in situ electrochemical AFM (EC-AFM) as an in situ probe, we study the influence of a cationic surfactant cetyltrimethylamminobromide (CTAB) on Ag growth during electrochemical deposition on Ag(100). The results show that the organic surfactant leads to a unique crystal growth habit. With CTAB present in the growth solution, Ag islands grow in a truncated pyramidal shape. To understand the shape evolution of the Ag islands, we utilize electron backscatter diffraction (EBSD) in conjunction with microscopic ellipsometry to characterize the facet-specific binding of the organic molecules to large-grained polycrystalline Ag substrates.
Schottky-Barrier Si Nanowire MOSFET: Effects of Source/Drain Metals and Gate Dielectrics
Authors: Yang Weifeng , Whang Sungjin , Lee Sungjoo , Zhu Haichen , Gu Hanlu , Cho Byungjin 
Published: April 2011

AbstractWe fabricated and studied the performance of Schottky-Barrier Si nanowire FETs (SiNW FET) by using Vapor-liquid-solid (VLS) grown Au-catalyzed SiNWs (20 nm). These devices were formed on various gate dielectrics (HfO2 or Al2O3) with different metal Source and Drain (S/D) regions (Pd, Ni). P-type behavior was observed and high Ion/Ioff ratio (~105) was achieved from undoped SiNW FETs. Besides, no ambipolar transportation was observed in our devices performance. This is possibly due to the small schottky barrier height for hole carriers at Source sides formed by high work-function metal. Furthermore, low subthreshold slope as 68mV/decade was obtained from SiNW FETs integrated with Ni S/D and Al2O3 High-¦gate dielectric.
New Palladium Nanomaterials for Catalysis: Mechanisms Controlling Formation and Evolution of Nanostructures in a Seed-Mediated Synthesis
Authors: Bisson Laure , Boissière Cédric , Sanchez Clément , Thomazeau Cécile , Uzio Denis 
Published: April 2011

AbstractMetallic nanoparticles are commonly used as the active phase of heterogeneous catalysts. Today, a current issue in catalysis research is to determine whether a specific crystallographic plane of the metallic nanoparticle is responsible for activity and selectivity properties in a structure sensible reaction. Following this purpose, metallic nanoparticles with specific morphologies have been studied. In the present work, palladium nanostructured particles are prepared in a surfactant mediated aqueous medium by a seeding growth approach, and present various morphologies : rods, tetrahedra and/or bipyramides, cubes, icosahedra... Synthesis of these nanoparticles and observation of their growth by a detailed Transmission Electron Microscopy study will be presented. We provide evidence that nucleation and growth of these particles are dominated by an aggregative mechanism. Moreover, upon ageing nanostructured particles undergo a ripening process to spherical morphology, attributed to an oxidative etching.
Vapor-phase Growth of High-quality ZnO Micro- and Nano-structures
Authors: Morales Monica , Look D. C. , Farlow G. C. , Claflin B. 
Published: April 2011

AbstractMicro- and nano-structures of ZnO have been grown on substrates from flowing carrier gases in a tube furnace. We have investigated how variations in the carrier gas composition, gas flow rate and the position of the substrate control the formation and the morphology of the nanostructures. The source material was pure zinc powder evaporated in the temperature range 500ºC to 650ºC in flowing Ar plus oxygen at atmospheric pressure. It was found that precise control of the gas composition, gas flow rate, and growth time was necessary for reliable deposition. It was also found that zinc powder must be washed to remove the surface oxide. Scanning electron microscopy (SEM) images of samples grown from a Zn powder source show forested needles approximately 100 nm in diameter by 1 micron long, and faceted rods from 500nm to 700nm thick. Photoluminescence measurements at 4 K show a dominant line at ~3.36eV with additional features at 3.32 and 3.37eV. The line widths are ~ 3.5meV, indicating good quality material. The usual green-band emission is also observed.
Optimizing Growth Rates and Thermal Stability of Silver Nanowires
Authors: Gates Byron D. , Gates Byron D. 
Published: April 2011

AbstractThere are multiple solution-phase approaches to synthesizing nanowires, yet some aspects of these syntheses are not well understood. Solution-phase methods are attractive for the ease of scaling to large quantities, which is a necessary step for applications utilizing nanowires. However, insight into the surface chemistry and mechanism of growth of the nanowires is essential for increasing the yield of nanowires. An improved synthesis of silver nanowires is presented along with insight into the mechanism of growth and stabilization of the nanowires. The techniques from this modified synthesis could be extended to a number of other solution-phase procedures to increase the yield of nanostructures.
Investigation on Site Density of Carbon Nanotube Forests
Authors: Liu Zhengchun , Lee Sang Hwui , Bajwa Navdeep , Ci Lijie , Kar Swastik , Ajayan Pulickel M. , Lu Jian-Qiang 
Published: April 2011

AbstractWe report on a method for direct measurement of site density of vertically-aligned carbon nanotubes (CNTs). Site density is an important parameter of vertically-aligned carbon nanotube forests for various applications. By freezing the CNT forests in a polymer matrix and exposing the CNT ends, we obtained the site density of vertically aligned multi-walled CNTs through SEM observation and particle counting. Site densities of multi-walled CNTs grown by two different CVD processes, ferrocene/xylene process and Fe-Al/ethylene process, were measured to be ∼10 tubes/Ým2 and ∼53 tubes/Ým2, respectively. The results of site density distributions indicate non-uniform growth of carbon nanotubes at the micrometer scale in both processes.
Low Temperature Growth and Application of Zinc Oxide Nanowires using Zinc Oxide Seeds
Authors: Sunyoung Lee , Hey Jin Myoung , Sunglyul Maeng , Sang-Hyeob Kim 
Published: April 2011

AbstractThe growth of ZnO nanowire arrays on a variety of substrates using a chemical wet process is presented. ZnO seeds can act as a nucleation layer for wire growth and ZnO nanowire arrays can have direct contact with a variety of substrates. The structural and optical properties of ZnO nanowire arrays grown at 90°C are investigated. FESEM and X-ray diffraction observations reveal that the crystalline ZnO nanowire arrays are preferentially oriented along the c axis. The room temperature photoluminescence (PL) measurements had shown ultraviolet peaks and a deep level peak. After annealing at 900°C for 1 min. by RTA, the deep level peak became much weaker and the band-edge emission PL was much stronger.
Fabrication of CNT/metal torsional resonator structures on GaAs
Authors: Hong Seung Sae , Bak Jung Hoon , Lee Byung Yang , Cho Sung Woon , Kim Young Duck , Hong Seunghun , Park Yun Daniel 
Published: April 2011

AbstractWe present a method to realize nanoelectromechanical systems (NEMS) resonator structures from carbon nanotubes (CNT)/metal layered composite structures. The method utilizes a self aligning process over a near 2-D CNT network on GaAs to realize resonator structures and a highly selective etchant, a standard citric acid/hydrogen peroxide solution, to achieve release of NEMS resonators from the substrate. We find this method along with critical point drying (CPD) to yield robust hybrid CNT/metal resonator structures with fundamental resonant frequencies in the 10 MHz range. With high reflectivity, conductivity, and bio-compatibility of metals, this fabrication method along with possible benefits of CNT have many application possibilities.
High-Current Reliability of Carbon Nanofibers for Interconnect Applications
Authors: Kitsuki Hirohiko , Suzuki Makoto , Ngo Quoc , Gleasson Kristofer , Cassell Alan M. , Ominami Yusuke , Moylan Christopher R. , Li Jun , Yang Cary Y. 
Published: April 2011

AbstractWe present a high-current reliability study of carbon nanofibers (CNFs) for interconnect applications. In situ scanning transmission electron microscopy (STEM) reveals structural damage to CNFs after current stress. The effect of heat dissipation on the current capacity is also discussed by using different experimental configurations. Long-time reliability tests are performed with a vertical via interconnect structure, showing promising high reliability of CNF interconnects for future electronic devices.