bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novel Approach for Biofouling-Release Materials with Interpenetrating Polymer Networks
Authors: Mori Kenji , Naito Masanobu , Nakai Takashi , Fujiki Michiya , Kawabe Takuma 
Published: April 2011

AbstractEnvironmentally friendly organic-inorganic hybrid materials with repellent activity against marine fouling organisms, such as blue mussel, have been developed using interpenetrating polymer networks (IPNs), composed of a 3-dimensional siloxane matrix of tetraethoxysilane (TEOS) and poly(vinylacetate) (PVAc). Facile bioassay using blue mussels allowed screening the adequate proportions of those components. The repellent activity of IPN with PVAc/silica reached approximately 90% at a specific fraction, relative to that of tributyl tin oxide (TBTO). On the other hand, poly(methylmethacrylate)(PMMA) /silica composite did not show marked repellent activity against blue mussel, even though chemical structure of MMA is similar to that of vinylacetate.
Arrayed Nanohydrogels for Protein Array Technology
Authors: Saaem Ishtiaq , Papasotiropoulos Vasilis , Wang Tongsheng , Soteropoulos Patricia , Libera Matthew 
Published: April 2011

AbstractThis paper describes studies of surface-patterned nanohydrogels and their use as possible substrates for high-density and high-sensitivity protein arrays. Nanohydrogels, approximately 200 nm in diameter, were created by locally crosslinking dry amine-terminated poly(ethylene glycol) [PEG] (5000 Da) thin films using a focused electron beam. These gels then had a dry height of 50 nm and a swell ratio of about five. They were patterned into arrays with approximately 1 μm inter-gel spacing. These arrayed gels were functionalized with Zinc Finger 9 (ZNF9), a nucleic-acid binding protein. As part of ongoing research, we are interested in how the performance of the functionalized gels compares to that of current commercial substrates. We show, using an assay that binds α-GST antibody to mediate attachment of GST-tagged ZNF9, that nanohydrogels have a consistently higher combination of fluorescent signal and signal-to-noise (SNR) ratio than the comparable commercial substrates. We further show that the SNR characteristic of our assay degrades slower on the nanohydrogel array than on a comparable microarray printed on an epoxide substrate, and we speculate that the difference is in part attributable to the fact that the nanohydrogel array presents a softer and more hydrophilic surface.
The Effect of Tethering on the Chemical Kinetics of Single Bonds
Authors: Nguyen-Duong Melanie , Koch Karl-Wilhelm , Merkel Rudolf 
Published: April 2011

AbstractWe investigated the force induced dissociation of single specific bonds between protein A and immunoglobulin G. In these experiments both proteins were tethered to microbeads. Pi-conewton forces were applied by means of an ultrasoft spring. Upon bond formation the thermal fluctuations of this soft spring were reduced. This resulted in a sizeable contribution to the free enthalpy of bonding. Including this effect we calculated the relation between the lifetime of bonds connecting both microbeads and the lifetime of the bond between free molecules. We found that the lifetime depended on the stiffness of the force probe. Moreover, the lifetime was reduced by almost two orders of magnitude. Both predictions were verified in our experiments.
Dynamics of DNA conformations and DNA-protein interactions
Authors: Metzler Ralf , Ambjörnsson Tobias , Lomholt Michael A. , Krichevsky Oleg 
Published: April 2011

AbstractOptical tweezers, atomic force microscopes, patch clamping, or fluorescence techniques make it possible to study both the equilibrium conformations and dynamics of single DNA molecules as well as their interaction with binding proteins. In this paper we address the dynamics of local DNA denaturation (bubble breathing), deriving its dynamic response to external physical parameters and the DNA sequence in terms of the bubble relaxation time spectrum and the autocorrelation function of bubble breathing. The interaction with binding proteins that selectively bind to the DNA single strand exposed in a denaturation bubble are shown to involve an interesting competition of time scales, varying between kinetic blocking of protein binding up to full binding protein-induced denaturation of the DNA. We will also address the potential to use DNA physics for the design of nanosensors. Finally, we report recent findings on the search process of proteins for a specific target on the DNA.
Finite conductivity effects and apparent contact angle saturation in AC electrowetting
Authors: Kumar Abishek , Pluntke Manuela , Cross Benjamin , Baret Jean-Christophe , Mugele Frieder 
Published: April 2011

AbstractWe measured the electrowetting behavior of aqueous salt solutions. By varying the conductivity and the frequency of the applied AC voltage we determined the range of the validity perfect conductor assumption of the standard electrowetting theory for the case of AC voltage. We show that the contact angle reduction is dramatically reduced at high frequency and low salt concentration due to Ohmic losses with the liquid. A simple RC-equivalent circuit model explains the observations. It is demonstrated that finite conductivity effects are more pronounced for sessile droplets than for droplets confined between to parallel plates.
Radial-breathing Mode Frequencies for Single-Walled Carbon Nanotubes of Arbitrary Chirality: First-Principles Calculations
Authors: Lawler Hadley Mark , Areshkin D. , Mintmire J.W. , White C.T. 
Published: April 2011

AbstractFirst-principles calculations are performed for the radial-breathing mode of all 105 single-walled carbon nanotubes within the rolling-geometry diameter range of 0.4 to 1.4 nm. The diameter dependence of the frequencies is analyzed in some detail, and compared with measurable parameters of bulk graphite. The frequencies are compared with those available from other first-principles work, and experimental studies.
Nanobubble Formation at the Solid-Liquid Interface Studied by Atomic Force Microscopy
Authors: Agrawal Abhinandan , McKinley Gareth H. 
Published: April 2011

AbstractThe formation of nanobubbles at solid-liquid interfaces has been studied using the atomic force microscopy (AFM) imaging technique. Nanobubble formation strongly depends on both the hydrophobicity of the solid surface and the polarity of the liquid subphase. While nanobubbles do not form on flat hydrophilic (silicon oxide wafer) surfaces immersed in water, they appear spontaneously at the interface of water against smooth, hydrophobic (silanized wafer) surfaces. From the experimental observations we draw the conclusion that the features observed in the AFM images are deformable, air-filled bubbles. In addition to the hydrophobicity of the solid surface, differences in solubility of air between two miscible fluids can also lead to formation of nanobubbles. We observe that nanobubbles appear at the interface of water against hydrophilic silicon oxide surfaces after in-situ mixing of ethanol and water in the fluid-cell.The shapes of the nanobubbles are well approximated by spherical caps, with width much larger than the height of the caps. We quantify the morphological distribution of nanobubbles by evaluating several important bubble parameters including surface coverage and radii of curvature. In conjunction, with an analytical model available in the literature, we use this information to estimate that the present nanobubble morphology may give rise to slip lengths ∼1–2 µm in pressure driven flows for water flowing over the hydrophobic surface. The consistency of the calculated slip length with the experimental values reported in the literature, suggests that the apparent fluid slip observed experimentally at hydrophobic surfaces may arise from the presence of nanobubbles.
Linearized Quantum Conductivity of Atomic Clusters and Artificial Molecules
Authors: Pozhar Liudmila A. 
Published: April 2011

ABSTRACTThe explicit expression for the linearized longitudinal quantum conductivity of inhomogeneous systems (such as semiconductor atomic clusters, artificial molecules, etc.) in weak electro-magnetic fields derived recently within a first principle quantum statistical mechanical approach in terms of the equilibrium two-time temperature Green functions (TTGFs) has been analyzed to develop analytical and computational means for its calculations. This has been done using a generalized continuous fraction method due to Zubarev and Tserkovnikov (ZT). The TTGFs have been related to Kubo's relaxation functions of the charge density and its gradients that can be computed using available quantum statistical mechanical algorithms and software. Thus, it becomes possible to predict the linearized quantum conductivity of any small system (in particular small semiconductor quantum dots (QDs)) as a function of external electromagnetic fields using a unified fundamental approach. This knowledge can be used to develop small semiconductor QD-based highly sensitive tunable sensors based on changes in the conductivity caused by external electromagnetic fields (in particular, radiation).
Cationic Lipid Modulates Phospholipid Adsorption on Silica
Authors: Moura Sérgio P. , Carmona-Ribeiro Ana Maria 
Published: April 2011

ABSTRACTAt 2 % cationic lipid and 98 % phospholipid, pH 6.3, in pure water, high affinity adsorption isotherms with limiting adsorption indicative of one bilayer deposition on each silica particle were obtained whereas for the other molar proportions tested, limiting lipid adsorption was either above or below the level expected for bilayer deposition. This suggested a modulating role for cationic lipid allowing control of total amount of lipid adsorbed on silica. Silica sedimentation documented from photographs was almost absent over a range of lipid concentrations where bilayer deposition was achieved.
Platinum nanoparticle encapsulation during hydrothermal growth of mesoporous oxides: Synthesis, characterization and catalytic properties
Authors: Rioux Robert M. , Song Hyunjoon , Hoefelmeyer James D , Niesz Krisztian , Grass Michael , Yang Peidong , Somorjai Gabor A 
Published: April 2011

ABSTRACTA synthetic method for the design of heterogeneous catalysts incorporating monodisperse platinum nanoparticles into ordered mesoporous oxide frameworks has been developed. Nanoparticles were synthesized in solution in the presence of surface templating polymer and encapsulated into mesoporous oxide matrices. After polymer removal by calcination, ethylene hydrogenation rates were consistent with previously reported results, while superior activity of low coordination atoms in small crystallites during ethane hydrogenolysis was demonstrated. Changes in reaction selectivity with particle size during the hydrogenation/dehydrogenation of cyclohexene were attributed to a hydrogen coverage effect influencing the hydrogenation pathway and the apparent structure sensitivity of the dehydrogenation pathway.
Quantitative Study of Au Catalytic Nanoparticles by Stem and Hrtem
Authors: Xu Fengting , Menard Laurent , Xu Huiping , Kang Joo , Gao Shangpeng , Wang Lin-lin , Frenkel Anatoly , Nuzzo Ralph G , Johnson Duane D , Yang Judith C 
Published: April 2011

ABSTRACTThe highly dispersed metal (e.g. Au) nanoparticles have exhibited exceptional catalytic activity for several reactions, including CO oxidation. Their high catalytic activity has been attributed to nanoparticles nano-structural effects (including cluster thickness, shape, chemical information, and number of atoms of the cluster). The three dimensional exact structure and chemical bonding state of these supported nanoparticles is still challenging to be quantified by conventional methods due to their limitations in understanding size distribution of supported metal nanoparticles that are usually less than 1 nm (< 100 atoms). In this paper, the structure of Au heterogeneous catalysts has been successfully characterized by High Resolution Electron Microscopy (HREM), Z-contrast Scanning Transmission Electron Microscopy (STEM). The ligand protected Au13 nanoparticles on TiO2 support have been studied by ozone and thermal treatments to remove the ligands. The ozone removal method results in the truncated cuboctahedral structure while the thermal treatment results in the cuboctahedral structure. The ozone treatment yields less Au nanoparticles sintering than thermal treatment. Their FCC structure was confirmed by quantified Z-contrast STEM, HREM and its Fourier transformation.
Study on the Synthesis of Carbon Nanotubes using the Catalyst Metal Deposited Carbon Cathode Electrode in a DC Arc Discharge Process
Authors: Kim Hyeon Hwan , Kim Hyeong Joon 
Published: April 2011

ABSTRACTCarbon nanotubes (CNTs) were grown using a dc arc discharge process and relevant process parameters were investigated. Unlike the usual process in which a carbon anode is filled with metal catalyst powder, CNTs were prepared using a carbon cathode on which the metal catalyst had been deposited using an electroplating system. Various transition metals, Ni, Co and Ti, were used as a catalyst. The results show that multi-walled carbon nanotubes (MWNTs) and single-walled carbon nanotubes (SWNTs) can both be synthesized using this technique. And yield and morphology of the prepared CNTs varied depending on the experimental condition and catalyst. While MWNTs were produced in the deposit and soot sample, SWNTs with diameters near 1nm were only detected in the soot collects. When Ni film was used as a catalyst, the yield of SWNTs was higher than in case of using Co or Ti film as a catalyst. From these results, the optimized preparing condition of CNTs and the properties of a good catalyst are discussed.
Selective Heating of Multiple Nanoparticles
Authors: Wijaya Andy , Brown Katherine Alice , Alper Joshua , Hamad-Schifferli Kimberly 
Published: April 2011

ABSTRACTA method for heating multiple types of magnetic nanoparticles independently is described. This technique exploits tuning of the size and material dependent properties of magnetic field heating of nanoparticles to allow independent heating by application of the field at different frequencies. Magnetic field heating experiments as a function of field frequency show that there is potential for this technique in vitro.
The Effect of Substrate and Catalyst Properties on the Growth of Multi-Wall Carbon Nanotube Arrays
Authors: Neralla Sudheer , Yarmolenko Sergey , Sankar Jag , Shanov Vesselin , Yun Yeo Heung , Schulz Mark J. 
Published: April 2011

ABSTRACTSelf-aligned arrays of long multi-walled carbon nanotubes (MWCNT) were grown by chemical vapor deposition (CVD) from a gas mixture of C2H4-H2-Ar-H2O at 750°C. A catalytically active alumina surfaces coated with a thin layer of iron and supported by a Si/SiO2 substrate were prepared using pulsed laser deposition method. Combinatorial approach has been used for optimization of catalytic properties of the multilayered system Si/SiO2/Al2O3/Fe. Sixteen different combinations of catalytic surfaces having thicknesses of Fe (0, 1, 2, and 3 nm), alumina (0, 10, 20 and 30 nm) per sample were deposited on two Si/SiO2 substrates with silica thickness 150 and 500 nm. To study the effect of alumina phase on efficiency of catalytic surfaces two substrate temperatures 200 and 700°C were used to produce amorphous and γ-alumina phases correspondingly. This approach allowed the optimal structure of catalytic surface to be determined from 64 different substrates on 4 samples in a single MWCNT growth experiment, for a given set of processing conditions. It was found that most efficient growth of MWCNT arrays on amorphous alumina occurred at Fe nanolayer thickness of 2 nm while catalyst having γ-alumina layer has tendency to be more efficient at higher thickness of Fe. Catalytic substrate containing amorphous alumina has less sensitivity to thickness of iron while γ-alumina based catalyst has significant variation in catalytic activity with change of iron content.
A New Intelligent Material Based on Long Carbon Nanotube Arrays
Authors: Shanov Vesselin , Yeo-Heung Yun , Schulz Mark , Gollapudi Ramanand , Yarmolenko Sergey , Neralla Sudhir , Sankar Jagannathan , Tu Yi , Subramaniam Srinivas 
Published: April 2011

ABSTRACTHighly aligned multi-walled carbon nanotube (MWCNT) arrays were synthesized on Si wafers. Water vapor was used to enhance the catalyst performance, which enabled continuous growth of MWCNT arrays for up to 3 hours. Various types of Fe patterning on a Si substrate with a multilayered structure were tested. MWCNT arrays up to 4 mm long were grown by Chemical Vapor Deposition (CVD). Environmental scanning electron microscopy was used to characterize the MWCNT morphology and showed that the nanotubes typically reveal a 20 nm outer diameter and 8 nm inner diameter. To investigate applications, a nanotube tower 1 mm × 1 mm × 4 mm in size was grown and peeled off the Si wafer. Each tower contains millions of individual nanotubes with 20–30 nm diameters. Electrochemical actuation of one MWCNT tower was demonstrated in a 2M NaCl solution. The MWCNT tower actuator operated up to 10 Hz without significantly decreasing strain. Only 1-2 volts was needed to obtain 0.2% strain. The aligned nanotube morphology of the tower is the reason for the high strain in the axial direction, which is an improvement compared to previously tested entangled buckypaper actuators. Cyclic voltammetry (CV) was performed to analyze the redox behavior of the nanotube tower used as an electrode. The CV response showed a sigmodal shape in a 6 mM K3(CN)6 ferrocyanide solution. This behavior provides ideal characteristics for biosensor development and application. Also, the measured electrical volume resistivity of the material was in the range of 0.1 ohm · cm. The overall improvement in the electrochemical actuation and electrical conductivity was much greater than previous nanocomposites obtained by dispersing powdered nanotubes into polymers. The demonstrated good properties suggest nanotube array towers can be considered a novel intelligent material.
Controlled Growth of Gold Nanorod Arrays from Polyethylenimine-coated Alumina Templates
Authors: Moon Jeong-Mi , Wei Alexander 
Published: April 2011

ABSTRACTAu nanorod arrays were grown by electrodeposition in Au-backed nanoporous alumina templates modified with polyethylenimine (PEI) as an adhesion layer. By varying the concentration and molecular weight of PEI, the length of nanorod arrays could be finely controlled. The local length distribution was extremely narrow with relative standard deviations on the order of 2% for rod lengths from 700 nm to 17 microns. The uniform growth rate appears to be determined by the adsorbed PEI matrix, which controls the growth kinetics of the grains comprising the nanorods. Templates coated with poly(acrylic acid) did not impart fine control in nanorod growth. The nanorods could also be thermally annealed within the template and released as monodisperse particles of uniform size.
Electric-Field-Induced Displacements in Pt/PZT/Pt/SiO2/Si System Investigated by Finite Element Method: Material-Constant Dependences
Authors: Okino Hirotake , Hayashi Masahiro , Iijima Takashi , Yokoyama Shintaro , Funakubo Hiroshi , Setter Nava , Yamamoto Takashi 
Published: April 2011

AbstractElectric-field-induced displacements of PZT film capacitor Pt/PZT/Pt/SiO2/Si(100) were calculated by finite element method (FEM) with changing all piezoelectric and elastic constants of PZT so as to discuss how to evaluate intrinsic d33 of piezoelectric thin films. Two kinds of conditions, namely, “ideal conditions” and “second-best conditions” are discussed. The ideal conditions indicate that the diameter of top electrode φTE is equal to or less than PZT film thickness tPZT and continuous PZT is etched to isolate the capacitor from the continuous piezoelectric film layer. Under the ideal conditions, d33 measured by atomic force microscopy (AFM) and double beam interferometry (DBI) were the same value that was equal to intrinsic d33 of PZT and was independent of other material constants. Under the second-best conditions, i.e. 20×tPZT < φTE for DBI and 20×tPZT < φTE < 0.5×(tsub: substrate thickness) for AFM, measured d33 depended on only d31, s11, s12 and s13, and obeyed the Lefki's equation qualitatively. However, quantitative differences between FEM analysis and the Lefki's equation were not negligible.
Enhanced Electrical properties in Mn-doped Bi3.25La0.75Ti3O12 thin films
Authors: Singh Sushil Kumar , Ishiwara Hiroshi 
Published: April 2011

AbstractMn-doped Bi3.25La0.75Ti3O12 (BLT) thin films were fabricated by depositing sol-gel solutions on Pt/Ti/SiO2/Si <100> substrates. The surface morphology and ferroelectric properties of Mn-doped BLT films depend upon the orientation of the films. Small amount of Mn-doping in BLT films influences the ferroelectric properties of the films, that is, it enhances the remanent polarization and reduces the coercive field. The 1% Mn-doped BLT films show enhanced remanent polarization and reduced the coercive field by about 22%. To the contrary, Mn-doping more than 1% decreases polarization gradually. Mn-doping significantly improves the fatigue resistance of BLT films. The reduced polarization in the 3.3% Mn-doped thin film recovers during switching cycles higher than 5 × 105. Under high switching field, the probability of field-assisted unpinning of domains is expected to be high and this may be the main cause for increase in polarization after 5 × 105 in the 3.3% Mn-doped BLT film.
A new model of imprint mechanism in ferroelectric memory
Authors: Miyazawa Hiromu , Hamada Yasuaki , Higuchi Takamitsu , Natori Eiji , Kijima Takeshi , Shimoda Tatsuya , Yoshiya Masato , Oguchi Tamio 
Published: April 2011

AbstractWe have studied imprint mechanism of ferroelectric memory based on the oxygen-vacancy screening model. Interface charge density and offset bias for PZT resulted from the imprint were estimated as a function of effective depth for diffusion of oxygen vacancy based on this model. In order to understand microscopic dynamics during the imprint that might affect the interface charge density, molecular dynamics simulation (MD) was carried out. Diffusion length during the real imprint test for PZT was estimated based on the diffusion constant obtained from the MD simulation. By using the diffusion length, interface charge density and, in turn, offset bias was quantitatively estimated. Based on the quantitative analysis, it is found that the oxygen-vacancy screening model with microscopic dynamics obtained from the simulation explains well the imprint mechanism for PZT materials family.
Spectral Characterization of Persistent Photo Conductance in SiC
Authors: Smith Steven , Evwaraye Andrew , Mitchel William 
Published: April 2011

AbstractThe transient photo response of 4H- and 6H-SiC specimens at various wavelengths has been studied using Optical Admittance Spectroscopy. Differences in the transient response were found for excitation and recombination for different specimens in both materials. The results indicate that optical excitation of charge carriers to the conduction band is a single transition, but recombination of free carriers from the conduction band is a process involving multiple transitions to the ground state mediated by deep centers in the material. Similarities in the persistent photoconductance after excitation from deep centers, and after excitation at above bandgap energies, suggest that carriers from the conduction band drop through deep centers on the way to the valence band.