bluuebunny/crossref_metadata_2025 huggingface dataset:
Deposition and Etching of Conformal Boron Films for Neutron Detector Applications
Authors: LiCausi Nicholas , Clinton Justin , Danon Yaron , Lu James J.-Q. , Bhat Ishwara B.
Published: September 2011

In this work, the deposition of boron using low pressure chemical vapor deposition (LPCVD) has been investigated on planar and deep reactive ion etched (DRIE) Si substrates. Deposition rate and conformal coverage have been studied. Additional studies of “dry” RIE etching and “wet” chemical etching of the deposited boron films are presented. Deposition rates as high as 1 μm/hr and conformal coverage ratios of ~80% have been achieved. Etching rates for various methods studied range widely from 0.35 μm/hr to 1.2 μm/min.
Towards Radiolabeled G∧C Module for Cellular Imaging of Bioactive Rosette Nanotubes
Authors: Alsbaiee Alaaeddin , St. Jules Mustapha , Beingessner Rachel L. , Fenniri Hicham
Published: September 2011

Rosette nanotubes (RNTs) are obtained through the self-organization of biologically inspired self-complementary guanine-cytosine modules (G∧C motif) under physiological conditions. These architectures can express bioactive molecules on their surface by functionalizing the G∧C motif prior to self-assembly. As a result, RNTs are promising drug delivery vehicles for the treatment of diseases such as cancer and inflammatory disorders. Towards these studies, we have explored the toxicity and immunological response of RNTs and are now focused on understanding their cellular uptake, biological distribution and kinetics in vivo. For these investigations, we need to construct a RNT labeled with a radionuclide that can be followed in vivo by SPECT (single photon emission computed tomography) imaging. In this proceeding, we describe a twin G∧C motif that is functionalized with mercaptoacetyl triglycine (MAG3). This is a well known ligand which is able to form a stable chelate with the radionuclides 99mTc or 186/188Re. In order to develop the chemistry for this radiolabeling strategy for the RNTs, we demonstrate the chelation of the MAG3 functionalized twin-G∧C motif with cold rhenium and investigate the self-assembly properties of the complex into RNTs under aqueous conditions.
Electrostatic and Steric Effect of Peptides Functionalized on Self-Assembled Rosette Nanotubes
Authors: El-Bakkari Mounir , Beingessner Rachel L. , Alshamsan Aws , Cho Jae-Young , Fenniri Hicham
Published: September 2011

Discrete nanoscale tubular architectures have received significant attention during the past decade because of their potential role in electronic and photonic devices, sensors, liquid crystals, artificial channel systems and biomedical engineering [1-2]. Our research group has reported the synthesis and characterization of the bicyclic G∧C motif, a self complementary DNA base analogue, which undergoes hierarchical self-assembly to form Rosette Nanotubes (RNTs) [3]. The stability of this system depends however, on functional group density (sterics) and net charge (electrostatics) on the RNT surface [5c]. To this end, we have synthesized several G∧C modules bearing oligopeptides with different lengths and net charge and investigated their self-assembling properties.
Characterization of bismuth telluride aerogels for thermoelectric applications
Authors: Dong Wenting , Rhine Wendell , Caggiano Greg , Evans Owen R. , Gould George , White John , Sharp Jeff , Gilbert Pat , Ganguly Shreyashi , Brock Stephanie L.
Published: September 2011

Refrigeration, air conditioning, and other cooling requirements in buildings, industry, and transportation sectors account for about 10 quads of U.S. primary energy consumption. Therefore, advanced technologies for space cooling in buildings and vehicles – as well as for refrigeration in residential, commercial, and industrial applications – that are more energy efficient, avoid net direct greenhouse gas emissions, reduce lifecycle costs, and can impact large markets are needed. Although current technologies are reaching their efficiency limits, thermoelectric (TE) materials can be used for cooling applications and have potential for significant improvements. Compared to traditional bulk phase TE materials, literature results suggest that nanometer-scale materials allow additional opportunities to improve the efficiency of TE materials. Aerogels are one type of nano-material that offers opportunities to increase the efficiency of TE materials by controlling particle size, particle composition and by reducing the thermal conductivity. Bismuth telluride (Bi2Te3) is the most studied TE material and our objective was to produce bismuth telluride aerogels with controlled microstructures and thermal conductivities to increase the TE figure of merit. Aspen Aerogels developed a novel synthesis method to prepare Bi2Te3 aerogels using the principles of colloidal chemistry and sol-gel chemistry. The reaction conditions were investigated and optimized so that gels could be obtained at low reaction temperatures. The gels were aged and dried using supercritical CO2. The aerogels were characterized by BET, XRD, and SEM. The best aerogels were hot pressed and Seebeck coefficients were determined. The synthetic approach developed and the properties of the aerogels will be presented and compared with Bi2Te3 aerogels and materials prepared by other methods.
Investigations on Plasmonic Modes of Noble Metal Nano-Disks Using High-Resolution Cathodoluminescence Imaging Spectroscopy
Authors: Kumar Anil , Fung Kin Hung , Fang Nicholas X.
Published: September 2011

In this work, we report investigations on plasmonic nano-disks using cathodoluminescence (CL) imaging and spectroscopy. 50 nm thick gold disks fabricated using electron beam lithography were studied and several modes were identified. Detailed analysis of the modes using monochromatic imaging and CL spectra showed strong size dependence. Our investigations on these plasmonic nano-disks allow understanding of light-matter interaction at nanoscale, with several potential applications including next generation plasmonic nano-lasers.
Towards the Reduction of Optical Losses in Transition Metal-Based Nanomaterials
Authors: Gavrilenko A. V. , Gonder C. A. , Baker D. J. , Gavrilenko V. I.
Published: September 2011

Equilibrium geometries and cohesion energies of Ag0.94Cd0.06, Ag0.94In0.06, Au0.94Cd0.06, and Au0.94In0.06 solid alloys have been studied from the first principles within the Density Functional Theory using ab initio pseudopotentials. Equilibrium geometries are obtained by total energy minimization method using the Local Density Approximation and Generalized Gradient Approximation methods. Optical functions are calculated within the independent particles picture. We report essentially different behavior of Cd and In impurity atoms in Au- and Ag-based alloys: the aggregated (or quasi aggregated) phases in In-containing alloys are expected in contrast to the alloys with Cd atom where homogeneous impurity distribution over the bulk should dominate. Study of optical spectra in Ag0.94Cd0.06 and Au0.94Cd0.06 alloys indicate that optical losses in visible and near ultraviolet spectral range remarkably increase at bigger Cd concentrations. In ultraviolet spectral region redistribution of optical oscillator strengths results in both increase and decrease of optical losses in selected spectral regions.
Tight Integration of Plasmonic Nanoresonators with On-chip Silicon Nitride Photonic Guided Wave Structures
Authors: Chamanzar Maysamreza , Hosseini Ehsan Shah , Yegnanarayanan Siva , Adibi Ali
Published: September 2011

Plasmonic nanoresonators can localize light beyond diffraction limit and can provide large field enhancements and thus can be used in sensing and spectroscopy applications. Here, we numerically show that efficient excitation of plasmonic resonances of nanoparticles is possible when they are integrated with Silicon Nitride waveguides in an integrated hybrid photonic-plasmonic platform.
Solution Growth and Characterization of Icosahedral Boron Arsenide (B12As2)
Authors: Whiteley C.E. , Zhang Y. , Mayo A. , Edgar J.H. , Gong Y. , Kuball M. , Dudley M.
Published: September 2011

The crystallographic properties of bulk icosahedral boron arsenide (B12As2) crystals grown by precipitation from molten nickel solutions were characterized. Large crystals (5-8 mm) were produced by dissolving the boron in nickel at 1150°C for 48-72 hours, reacting with arsenic vapor, and slowly cooling to room temperature. The crystals varied in color from black and opaque to clear and transparent. Raman spectroscopy, x-ray topography (XRT), and defect selective etching revealed that the B12As2 single crystals were high quality with low dislocation densities. Furthermore, XRT results suggest that the major face of the plate-like crystals was (111) type, while (100), (010) and (001) type facets were also observed optically. The predominant defect in these crystals was edge character growth dislocations with a <001> Burgers vector, and <-110> line direction. In short, XRT characterization shows that solution growth is a viable method for producing good quality B12As2 crystals.
Using Antibiotic Conjugated Magnetic Nanoparticles and a Magnetic Field for the Treatment of Bone Prosthetic Infections
Authors: Taylor Erik N. , Aninwene George E. , Webster Thomas J.
Published: September 2011

Bacterial infection of bone (called osteomyelitis) is of great concern to the medical community. In addition to bone, numerous medical devices are susceptible to microbial colonization when implanted. These infections are chronic since bacteria form a robust adhesion to surfaces, can be protected by sticky slime matrix (called a biofilm) from the body’s immune system (which would otherwise naturally clear the bacteria), and antibiotic treatments may not resolve such infections (due to antibiotic resistance). Here, the multifunctional properties of magnetic nanoparticles (termed here superparamagnetic iron oxide nanoparticles, or SPION) will be explored for their antibacterial activity, magnetic properties, and drug deliverable properties. This study provides a first step towards the development of a new type of pharmaceutical useful for orthopedic or other device related infections by demonstrating physical (magnetic) control of antibiotics towards bacteria and biofilms.
The Synthesis and Self-Assembly Studies of Two Bioactive BMP-7 Short Peptides Modified Rosette Nanotubes for Bone Tissue Engineering
Authors: Alsbaiee Alaaeddin , El Bakkari Mounir , Fenniri Hicham
Published: September 2011

Bone fractures are one of the most common bone complications. In more severe cases, bone fixation is accomplished using titanium (Ti) implant materials. Unfortunately, the need for revision surgery often arises due to implant loosening and/or deterioration of the implant/bone interface. Rosette nanotubes (RNTs) are a class of self-assembled organic materials obtained through the self-assembly of a guanine-cytosine hybrid base (G∧C motif). These organic materials have been found to increase osteoblast (bone forming cells) adhesion and hydroxyapatite deposition (bone regeneration) on titanium implants as well as on engineered hydrogels. In order to increase the bioactivity of RNTs to enhance bone cell function on Ti implants, two RNT motifs functionalized with different bioactive deca-peptides (A, B) chosen from the knuckle region of bone morphogenic proteins-7 (BMP-7) were synthesized. Their self-assembly process was investigated in water using UV-Vis and SEM techniques.
Science Saturdays: A Simple Science Outreach Model to Achieve Broad Impact
Authors: Ramirez Ainissa G.
Published: September 2011

The National Science Foundation (NSF) evaluates grant applications based on two criteria: intellectual merit and broader impact. The broader impact criterion (BIC), or the science outreach criterion, is intended to connect science, technology, engineering, and math (STEM) research to the general public, and has grown in its relevance for successful grants. A method to increase the competitiveness of a grant application and, in turn, the quality of science outreach programs is to suggest successful science outreach models for connecting scientists to the public. Science Saturdays is a fun science lecture series for the general public that is a simple, scalable, and transferable model. Its main mission is to introduce participants to excellent communicators of science and to shatter stereotypes about those who do science. It aims to inspire and motivate children as they traverse the STEM pipeline by emphasizing that science is fun. This paper discusses the elements needed to create this outreach program and the lessons learned from its development.
The Undergraduate Science Research Experience (USRE) and its Transformative Nature for Houston Community College Students
Authors: Sheinberg Bartlett M.
Published: September 2011

Since 2005 the author has provided community college science and engineering students the opportunity to conduct substantive summer research projects in the areas of materials science, physical sciences, engineering disciplines and other multidisciplinary research areas. To date, nineteen students have participated in research experiences at regional universities and NASA-Johnson Space Center. This paper will examine the genesis of the program, providing an overview of the program structure, the role that materials research has played in the success of the various student experiences, and thoughts on future directions and improvements.
Magnetocaloric Properties Desired for Magnetic Refrigeration System near Room Temperature
Authors: Wada H.
Published: September 2011

In order to realize the magnetic refrigeration system, it is necessary to develop a 100 W class refrigerator with COP > 7.5. This requires us to find new magnetic refrigerant materials, of which cooling capacity is 2.5 times higher than that of Gd. In this paper, first we discuss the cooling capacity of magnetic refrigerant materials to achieve COP = 7.5. Then, we compare the experimental results of MnAsSb, MnFe(PGe) and La(FeCoSi)13 compounds with the calculated cooling capacity. It is suggested that a composite layer material of MnFe(PGe) would show excellent cooling capacity in the temperature span of 20 K.
School-based Clubs as a Mechanism to Increase Student Interest in Materials Science Engineering and Nanotechnology among Underserved Groups
Authors: Dika Sandra L. , Alvarez Jaquelina E. , Santos Jeannette , Suárez O. Marcelo
Published: September 2011

Since 2005, the University of Puerto Rico-Mayagüez (UPRM) has co-facilitated materials science and engineering (MSE) clubs at low-income middle and high schools in Western Puerto Rico to increase awareness and interest in the areas of materials science, nanotechnology, and engineering. In this article, we describe the club activities and share the results of the 2009 end-of-year assessment regarding knowledge, interest, and educational aspirations in MSE, along with differences based on gender, parent education level, and school level. Overall, participants expressed positive opinions about engineering as a career. While students expressed high interest in pursuing university studies in science and engineering, some differences became apparent based on gender, parent education level, and school level. There were also differences between boys and girls in perceived knowledge gains. The results of this assessment provide promising evidence that school-based MSE clubs may help attract underserved students into the MSE pipeline.
Ultrafine Silicon Nano-wall Hollow Needles and Applications in Inclination Sensor and Gas Transport
Authors: Sanaee Z. , Mohajerzadeh S. , Mehran M. , Araghchini M.
Published: September 2011

We report on the realization of high precision hollow structures directly on silicon suitable for liquid and gas/vapor transport. The formation of hollow structures requires high aspect ratio etching combined with bulk back-side micro-machining to realize silicon-based membranes. The use of a slant angle deposition method has been used as an alternative method for three-dimensional lithography. The transfer of acetone vapor through such tiny holes shows an anomalous behavior where a sharp rise is observed followed by an exponential and gradual decay. These structures can be eventually used as mass ion separation devices.
Macroporous Carbon Monoliths with Large Surface Area for Electric Double-Layer Capacitor
Authors: Hasegawa George , Aoki Mami , Kanamori Kazuyoshi , Nakanishi Kazuki , Hanada Teiichi , Tadanaga Kiyoharu
Published: September 2011

Macro/meso/microporous carbon monoliths doped with sulfur have been prepared from sulfonated polydivinylbenzene networks followed by the activation with CO2 resulted in the activated carbon monoliths with high surface area of 2400 m2 g−1. The monolithic electrode of the activated carbon shows remarkably high specific capacitance (175 F g−1 at 5 mV s−1 and 206 F g−1 at 0.5 A g−1).
Ionic Electroactive Polymer Actuators with Aligned Carbon Nanotube/Nafion Nanocomposite Electrodes
Authors: Liu Yang , Liu Sheng , Cebeci Hülya , Guzman de Villoria Roberto , Lin Jun-Hong , Wardle Brian L. , Zhang Q. M.
Published: September 2011

Recent advances in fabricating controlled-morphology vertically aligned carbon nanotube (VA-CNTs) with ultrahigh volume fraction create unique opportunities for markedly improving the electromechanical performance of ionic polymer conductor network composite actuators (IPCNCs). Actuator experiments show that the continuous paths through inter-VA-CNT channels and low electrical conduction resistance due to the continuous CNTs in the composite electrodes of the IPCNC lead to fast ion transport and actuation speed (>10% strain/second). One critical issue in developing advanced actuator materials is how to suppress or eliminate unwanted strains generated under electric stimulation, which reduce the actuation efficiency and also the actuation strains. We observe that the VA-CNTs in the composite electrodes yields non-isotropic elastic modulus that suppresses the unwanted strain and markedly enhances the actuation strain (>8% strain under 4 volts). A transmission line model has been developed to understand the electrical properties of the actuator device.
Deformation Behavior of Natural Wood Having Hierarchical Structure Under A Compression State
Authors: MIKI Tsunehisa , SUGIMOTO Hiroyuki , KANAYAMA Kozo
Published: September 2011

A large deformation of bulk wood using slipping between the wood cells has been found just like a plastic deformation generated by slip band in metallic materials. This phenomenon is caused by the hierarchical structure of the wood cell, and the intercellular layer becomes selectively softened in moistened states of wood. In such conditions, bulk wood subject to compression at elevated temperatures can easily be deformed perpendicular to the longitudinal direction of the cells by shear flow stress after being collapsed.
Development of a Robust Design of a Wet Etched Co-integrated Pressure Sensor
Authors: Schreiber-Prillwitz Wolfgang , Saukoski Mikko , Chmiel Gerhard , Job Reinhart
Published: September 2011

The performance of a co-integrated silicon pressure sensor for the 1-bar full scale range was optimized. A gain in signal of ca. 5% was calculated and verified by optimizing the piezoresis-tors position on the membrane. The influence of alignment errors between the backside cavity mask and the positions of the piezoresistors on the membrane’s front side were calculated. De-pending on the asymmetry, a maximal electrical signal deviation of 1% was found. The impact of underetching effects (KOH) at the backside mask on electrical signals was also analyzed. Un-deretching has a certain range, alters the membrane size, and has a strong impact on sensor per-formances. In a worst case scenario signal variations caused by underetching could be finally reduced from 15% to 4%.
Carbon-Rich Nanostructures from Molecular Precursors
Authors: Hoheisel Tobias N. , Szilluweit Ruth , Schrettl Stephen , Frauenrath Holger
Published: September 2011

A synthesis for protected, glycosylated, amphiphilic oligo(ethynylene)s was developed. After their deprotection, two different glycosylated hexa(ethynylene)s were investigated for their self-assembly properties as well as their reactivity in aqueous solutions and at the air-water interface. Aggregation was observed in aqueous solution by UV spectroscopy, and the molecules formed films at the air-water interface.
Measurements of Resonance Frequency of Parylene Microspring Arrays Using Atomic Force Microscopy
Authors: Gaire C. , He M. , Zandiatashbar A. , Wang P.-I. , Picu R. C. , Wang G.-C. , Lu T.-M.
Published: September 2011

A mechanical vibration system was made by sandwiching an array of parylene-C microsprings between two flat plates of Si. This system was driven mechanically in forced oscillation using a piezo transducer attached to the bottom Si plate. An atomic force microscope was used to record the displacement of the top plate in both the contact and non-contact modes. At the resonance, the system was observed to give large vertical displacement amplitude of up to 100 nm with a Q-factor of up to 900.
Project VISTA: Building University/K-12 Learning Communities by Developing Materials Science Experiments
Authors: Bakker Martin G. , Gleason Jim , Nichols Sherry , Kuntz Aaron , Sundberg Cheryl , Busenlehner Laura , Chopra Nitin , Evans Victoria , Spencer Rosin P. , Murphy Amy K.
Published: September 2011

One consequence of “high stakes testing” in Tuscaloosa area schools has been exclusion of materials science faculty from any meaningful participation in middle and high school classrooms. Beyond the loss of resources from the classroom that Materials Science faculty and their students represent, this also has negative consequences for faculty wanting to build ties to schools to address NSF’s “broader impact” criteria. A group of STEM and Education faculty at The University of Alabama have been testing a team based approach designed to overcome the systemic constraints that prevent effective STEM/K-12 collaboration. Teams consisting of a high school teacher, a STEM faculty member, and a STEM graduate student have spent three weeks during summer 2010 to identify/develop and implement an inquiry based science experiments. The experiments are being tested on science campers at McWane Science Center prior to being assessed in the teachers’ classrooms during the fall semester. The experiments were chosen by each team and represent significant advances over those currently available in the schools. By setting a problem that no team member is able to solve alone an environment was produced where success requires meaningful collaboration. Preliminary qualitative evaluation indicates deeper understanding of the school environment by the STEM faculty and greater respect for the skills teachers bring to this endeavor. Successes in this pilot program have generated credibility with the local school district, opening the door to scaling up the project, and developing further positive ties. Incorporation of lead teachers from Alabama Science in Motion also allows the experiments developed to be widely disseminated throughout Alabama, as well as providing a mechanism to identify existing experiments to enhance.
On the Electrochemical Properties of α-Li3FeF6 Prepared by Precipitation from Aqueous-Alcohol Based Solutions
Authors: Basa A. , Gonzalo E. , Kuhn A. , García-Alvarado F.
Published: September 2011

The α-polymorph of Li3FeF6 has been prepared from aqueous-based solution by precipitation under different conditions to obtain small particles. Several alcohols have been used to vary the precipitation media. Among them 2-propanol has been found to provide particles of about 100 nm under controlled conditions of temperature and H2O: R-OH volume ratio. The average particle size of some of the as-prepared samples is smaller than that obtained for those samples obtained by precipitation in water. However, the expected enhancement of electrochemical performances does not occur for the as-prepared samples. Inserted amount of lithium into the cryolite structure of Li3FeF6 increases significantly only when composites of asprepared Li3FeF6 and carbon are milled mechanically. For example 12h milling is needed to reach 64 mAh/g (45% of theoretical capacity).
Atomic Layer Deposition of Gallium-Doped Zinc Oxide Transparent Conducting Oxide films
Authors: Chalker Paul R. , Marshall Paul A. , Romani Simon , Rosseinsky Matthew J. , Rushworth Simon , Williams Paul A. , Buckett John , McSporran Neil , Ridealgh John
Published: September 2011

Thin transparent conducting oxide (TCO) films of gallium-doped zinc oxide have been deposited on glass substrates by atomic layer deposition (ALD) using diethyl zinc, triethyl gallium and water vapour as precursors. The gallium-doped zinc oxide films were deposited over the temperature range 100-350°C. Transmission electron microscopy reveals that the as-deposited films are polycrystalline in character. The electrical resistivity of the gallium-doped zinc oxide films was evaluated using four-point probe and contactless measurement methods as a function of film thickness. The lowest sheet resistance of 16 Ω/☐ was measured from a film thickness of 400nm and a gallium content of 5 atomic percent. The electron Hall mobility of this film was 12.3 cm2/Vs. The visible transmittance of the films was 78% with a haze of 0.2%.
Bandgap engineered high mobility indium oxide thin films for photovoltaic applications
Authors: Gupta R.K. , Ghosh K. , Kahol P.K.
Published: September 2011

Magnesium and titanium doped indium oxide (IMTO) thin films were grown using pulsed laser deposition technique. Magnesium was added to enhance the bandgap, whereas titanium was added to improve carrier concentrations and mobility of indium oxide films. The effect of growth temperature on structural, optical, and electrical properties were studied. It was observed that the optical transparency of the films strongly depends on growth temperature and increases with increase in growth temperature. The films grown at 600 °C showed optical transparency > 85%. We observed widening in bandgap of indium oxide by doping with magnesium and titanium. The bandgap of IMTO films increases with increase in growth temperature. The maximum bandgap of 3.9 eV was observed for film grown at 600 °C. It was observed that growth temperature strongly affects the electrical properties such as resistivity, carrier concentration, and mobility. The electrical resistivity and mobility of the films increases with increase in growth temperature. On the other hand, carrier concentration decreases with increase in growth temperature. Temperature dependence electrical resistivity measurements showed that films grown at low temperatures are semiconducting in nature, while films grown at high temperature showed transition from semiconducting to metallic behavior. These wide bandgap, highly transparent, and high mobility films could be used for photovoltaic applications.
Effect of Growth Conditions on Electronic and Structural Properties of GZO Films Grown by Plasma-enhanced Molecular Beam Epitaxy on p-GaN(0001)/Sapphire Templates
Authors: Liu H.Y. , Avrutin V. , Izyumskaya N. , Reshchikov M.A. , Wolgast S. , Kurdak C. , Yankovich A.B. , Kvit A. , Voyles P. , Özgür Ü. , Morkoç H.
Published: September 2011

We report on a strong effect of p-GaN surface morphology on the growth mode and surface roughness of ZnO:Ga films grown by plasma-assisted molecular-beam epitaxy on p-GaN/c-sapphire templates. A range of ZnO:Ga surface morphologies varying from rough surfaces with well defined three-dimensional islands, capable to enhance light extraction in light-emitting diodes, to rather smooth surfaces with a surface roughness of ~ 2 nm suitable for vertical-cavity lasers can be achieved by controlling the surface morphologies of p-GaN. Optical transmittance measurements revealed high transparency exceeding 90% in the visible spectral range for ZnO:Ga with both types of surface morphology.
Surface Characterization of Ga-doped ZnO layers
Authors: McNamara J.D. , Ferguson J.D. , Foussekis M. , Ruchala I. , Reshchikov M.A. , Baski A.A. , Liu H. , Avrutin V. , Morkoç H.
Published: September 2011

Epitaxial ZnO layers heavily doped with Ga (GZO) were grown at 400 °C under metaland oxygen-rich conditions in terms of metal-to-reactive oxygen ratio by plasma-assisted molecular beam epitaxy (MBE). Several atomic force microscopy (AFM) techniques were used to characterize the surface morphology and electrical properties of these GZO films in ambient conditions. Local I-V spectra indicate that layers grown under both O-rich and metal-rich conditions are highly resistive until a relatively high voltage sweep (±12 V) is used. After removal of an insulating surface layer, conduction is possible at lower voltages, but eventually the film resistivity increases and it again becomes insulating. In addition to local I-V spectra, local charge injection and subsequent surface potential measurements were used to probe surface charging characteristics. For charge injection experiments, a reverse-bias voltage is applied to the sample while scanning in contact mode with a metallized tip. The resultant change in surface potential due to trapped charge is subsequently observed using scanning Kelvin probe microscopy (SKPM). The layers deposited in a metal-rich environment demonstrate the expected behavior, but the O-rich layers show anomalous negative and positive charging. Finally, surface photovoltage (SPV) measurements using above-bandgap UV illumination were performed. The GZO layers produce SPV values of 0.4 to 0.5 eV, where the films deposited in an O-rich environment have slightly higher SPV values and faster restoration.
Photodeposition of Metal Sulfide Quantum Dots on Titanium(IV) Dioxide and its Applications
Authors: Tada Hiroaki
Published: September 2011

In situ photodeposition techniques taking advantage of the TiO2 photocatalysis have been developed for coupling metal sulfide quantum dots (QDs) and TiO2 at a nonoscale. The coupled metal sulfide-TiO2 systems possess the following characteristics: (I) a large amount of metal sulfides can be directly formed on TiO2 during a fairly short period with excellent reproducibility, (II) the band energies of metal sulfides QDs are widely tunable by irradiation time, (III) metal sulfide QDs can be deposited on not only the external surfaces but also the inner ones of mesoporous TiO2 nanocrystalline films without pore-blocking, (IV) the simple solution-based technique at low temperature enables the low-cost production, (V) this technique has a wide possibility for coupling TiO2 and narrow gap metal sulfides. These unique features produce the excellent performances of the resulting heteronanojunaction systems as the photoanodes for QD-sensitized solar cells.
Concepts of metal-organic decomposition (MOD) silver inks for structured metallization by inkjet printing
Authors: Schoner Claudia , Jahn Stephan F. , Jakob Alexander , Blaudeck Thomas , Lang Heinrich , Baumann Reinhard R.
Published: September 2011

In this contribution, we report on the optimization of a metal-organic decomposition (MOD) ink based on silver(I) complexes by a systematic variation of the ink formulation. As a result, three different ink concepts turned out to be printable and resulting in a sufficiently high contour definition, layer homogeneity, and conductivity. The ink concepts include increase of the solid load, the usage of N-methyl-2-pyrrolidone (NMP) as a humectant with low vapor pressure, addition of co-solvents such as diethylene glycole and addition of sodium lauryl sulfate (SLS) as stabilizing ligand. It turns out that, for silver precursor concentrations of 40 wt%, the addition of 1 wt% SLS to aqueous inks leads to elevated conductivity up to 3.2x107 Sm-1 at maintained printability and an improved contour definition with respect to pure aqueous inks.
Reduced Resistance to Air Flow from Nanomodified Endotracheal Tubes
Authors: Machado Mary C. , Tarquinio Keiko M. , Webster Thomas J.
Published: September 2011

Ventilator associated pneumonia (VAP) is a serious and costly clinical problem. Specifically, receiving mechanical ventilation over 24 hours increases the risk of VAP and is associated with high morbidity, mortality and medical costs. Cost effective endotracheal tubes (ETTs) that are resistant to bacterial infection would help to prevent this problem. The objective of this study was to determine differences in bacterial growth on nanomodified and unmodified ETTs under dynamic airway conditions, a bench top model based upon the general design of Hartmann et al. (1999) was constructed to test of the effectiveness of nanomodified ETTs under the airflow conditions present in the airway. Twenty-four hour studies performed in a dynamic flow chamber showed a marked difference in the biofilm formation on different areas of unmodified tubes. Areas where tubes were curved, such as at the entrance to the mouth and the connection between the oropharynx and the larynx, seemed to collect the largest amount of biofilm. On the nanomodified tubes biofilm formation was markedly different occurring on smaller pieces.

The biofilm formation on ETTs in the airflow system after 24 hours showed a large difference depending upon where tubes were oriented within the apparatus. This illustrates the importance of dynamic flow on biofilm formation in pediatric ETTs. It is of particular interest that increased biofilm density on both unmodified and nanomodified tubes appeared to occur at curves in the tube where changes in flow pattern occured. This emphasizes the need for more accurate models of airflow within pediatric ETTs, suggesting that not only does flow affect pressure gradients along the tube, but in fact, determines the composition of the film itself. More testing is needed to determine the effects of biofilm formation on the efficiency of ETT under airflow, however this study provides significant evidence for nanomodification alone (without the use of antibiotics) to decrease bacteria function.
Iron fortification: Flame-made nanostructured Mg- or Ca-doped Fe oxides
Authors: Knijnenburg Jesper T.N. , Hilty Florentine M. , Teleki Alexandra , Krumeich Frank , Hurrell Richard F. , Zimmermann Michael B. , Pratsinis Sotiris E.
Published: September 2011

Iron deficiency affects approximately 2 billion people worldwide, especially young women and children. Food fortification with iron is a sustainable approach to alleviate iron deficiency but remains a challenge. Water-soluble compounds with high bioavailability (e.g. the “gold standard” FeSO4) usually cause unacceptable sensory changes in foods, while compounds that are less reactive in food matrices are often less bioavailable. Solubility (and therefore bioavailability) can be improved by increasing the specific surface area (SSA) of the compound, i.e. decreasing its particle size to the nm range. Here, iron oxide-based nanostructured compounds with Mg or Ca are made using scalable flame aerosol technology. Addition of either element increased iron solubility to a level comparable to iron phosphate. Furthermore, these additions lightened the powder color and sensory changes in fruit yoghurt were less prominent than for FeSO4.
Space Heritage: The Apollo Heat Shield; Atmospheric Reentry Imprint on Materials’ Surface
Authors: Szczepanowska Hanna , Mathia Thomas G.
Published: September 2011

The heat shield is part of a thermal protective system (TPS) essential in shielding the cargo of a spacecraft during reentry to the earth’s atmosphere. The ablated surface of the heat shield is a testimony to the harsh reentry environment, evidenced in melting and charring among other phenomena that occur during reentry at velocity of 9-11 km/sec. The aim of this study was to extrapolate information about atmospheric reentry from the surface of the ablated material. A sample of the heat shield from the test vehicle of the Apollo Program, AS-202, was the subject of the analysis.

For the preliminary studies, selected investigation modes from the Global Optimal Strategy model, developed to identify wear of engineering surfaces, were applied: examination of structure, optical observation, physico-chemical characterization and surface morphology. Instrumentation used included: microscopic surface analysis with Extended Depth of Field composite images (EDF), Fourier transform infrared spectroscopy (FTIR), attenuated total reflectance (ATR), confocal scanning laser microscopy and laser scanning microscopy. The Apollo Program testing vehicle AS-202 (1966) ablated specimen sample was obtained from the collection of the National Air and Space Museum (NASM), Smithsonian Institution, Washington DC. The authors combine their diverse experiences in tribology and in artifacts’ museum conservation so as to contribute to the space heritage material science. This study represents one of the building blocks of a larger project, the Fundamental Model of public outreach and perception (FAM-pop) of complex aerospace technologies.
Mechanical Properties of Vacancy-containing Graphene and Graphite Estimated by Molecular Dynamics Simulations
Authors: Ito Akihiko , Okamoto Shingo
Published: September 2011

Using molecular dynamics (MD) simulation, we investigated the mechanical properties of graphene and graphite, which contain cluster-type vacancies. We found that as the vacancy size increases, the tensile strength drastically decreases to at least 56% of that of pristine graphene, whereas Young’s modulus hardly changes. In vacancy-containing graphene, we also found that slip deformation followed by fracture occurs under zigzag tension. In general, tensile strength decreases as the size of cluster-type vacancies increases. However, the tensile strength of graphene with a clustered sextuple vacancy increases as the vacancy disappears because slip deformation proceeds. Furthermore, we found that slip deformation by vacancies in graphite occurs less easily than in graphene.

Our results suggest that the shape of vacancies affects the strengths of graphene and graphite.
Influence of Post-annealing Temperature on the Properties of Ti-Doped In2O3 Transparent Conductive Films by DC Ratio-frequency Sputtering
Authors: Li Lei , Chen Chen , Dong Chengjun , Cao JiaJia , Dang Jingmin , Wang Yiding
Published: September 2011

In this paper, titanium doped (2 wt. %) indium oxide (TIO) thin films deposited on quartz substrates by DC sputtering were presented. Dealt with different temperatures from 420°C to 620°C of post-annealing in vacuum for 40 minuets, the samples display different optical and electric properties. The deposited films exhibited polycrystalline in the preferred (222) and (440) orientation, with higher mobility (up to 48.6 cm2/VS) and lower resistivity (1.26 ×10-4Ω·cm) at the post-annealing temperature of 520°C. The average optical transmittance of the films is over 92% in a wavelength range from 300 to 1100 nm and the transmittance has only around 1.8% change with different post-annealing temperatures.
Mass-printed integrated circuits with enhanced performance using novel materials and concepts
Authors: Schmidt Georg C. , Bellmann Maxi , Kempa Heiko , Hambsch Mike , Reuter Kay , Stanel Michael , Hübler Arved C.
Published: September 2011

Printed electronics is a seminal technology for the production of simple disposable electronic products. In comparison to conventional silicon electronics it offers the possibility to use potentially cheap materials (e.g. polymers) which can be processed as solutions or dispersions by means of highly productive mass printing technologies. One main aim is the production of fully mass printed electronic circuits for the identification of single items, which should not cost more than one cent per tag. For the realization several challenges have to be clarified. On the one hand the performance of the - often organic - materials has to be increased in interaction with the used printing technologies. On the other hand the printing methods themselves have to be adapted and continuously improved. Alternatively, new approaches for the preparation of structured thin films have to be developed. This paper introduces a new technique for the production of source/drain electrodes with high resolution.
Dinosaur and Crocodile Fossils from the Mesozoic of Portugal: Neutron Tomography and Synchrotron-Radiation Based Micro-Computed Tomography
Authors: Martins Rui M.S. , Beckmann Felix , Castanhinha Rui , Mateus Octávio , Klaus Pranzas Philipp
Published: September 2011

Portugal is ranked within the 10 countries with the most dinosaur taxa and the Lourinhã Formation is known by the Late Jurassic findings of dinosaurs and other fossils. In many cases, studies of the external morphological characteristics of the fossils are not sufficient to extract all the information for a paleontological study and, thus, observations of internal structures, using non-destructive techniques, are required. The fossils studied in the present work belong to the Museum of Lourinhã. The access to the Geesthacht Neutron Facility in Germany allowed us to characterize a jaw of the dinosaur Baryonyx walkeri specimen and the jaw of a crocodile (possibly a Tomistomidae) by Neutron Tomography. The study allowed us to detect the presence of teeth inside the jaws and it provides valuable information about the development of its dental characteristics. Synchrotron radiation based micro-computed tomography studies on tiny samples have been performed at the beamline HARWI II operated by the Helmholtz-Zentrum Geesthacht at the storage ring DORIS III at the Deutsches Elektronen–Synchrotron DESY in Hamburg, Germany. The first data recorded for eggshells collected in the Lourinhã Formation is shown. It allowed us to visualize the morphology of the pores and their connectivity in the eggshells, providing information that is either exceedingly difficult or impossible to obtain by traditional methods based on section cutting.
Interim Report on THE LIGHTFASTNESS CORRELATION PROJECT
Authors: Gottsegen Mark D.
Published: September 2011

This paper describes the five-year Lightfastness Correlation Project that I am conducting in sixteen institutions in the US and Western Europe, with the support of the Samuel H. Kress Foundation.

Dr. Robert L. Feller, a scientist at the National Gallery of Art, published several papers in the 1970s in which he speculated that a certain duration of time could be correlated, in a general way, to the color changes noted in the Blue Wool Textile Fading Cards. Museums use the cards as inexpensive dosimeters, put somewhere in a gallery along with the art. Enough is known about their behavior to have confidence in their ability to indicate when it is time to remove an object from exhibition.

The Blue Wools are also used in two Standards developed by ASTM International’s Subcommittee D01.57 on Artists’ Paints and Related Materials. ASTM D 5383 and ASTM D 5398 are simple lightfastness test methods. In them, the Blue Wool cards are exposed to natural daylight along with any colored material, and are used to tell the artist when it’s time to stop the test and as a rating device.

Another ASTM Standard from D01.57, ASTM D4303, uses instruments to control the accumulated amount of natural daylight, or simulated daylight in a xenon arc light exposure machine. It also uses a spectrophotometer to calculate the color change that can occur in a test sample, expressed in CIE L*a*b*. There is also a standard formula for calculating color change that results in a single number, expressed as Delta E, or ∆E.

The ∆E number is used by ASTM D01.57 to assign lightfastness ratings to artists’ coloring materials covered by its Specifications for various products. Initial development of the ASTM methods began in 1977; we have 33 years of data that confirms the worth of the methods used in our testing.

What is the relationship between the results of Blue Wool testing and the results using D01.57’s technical ∆Es? This is a fundamental question we have yet to thoroughly examine. We have begun to work on the problem, using accelerated natural and artificial light sources as in ASTM D 4303. But no one has ever tried to compare the results of these two test methods in a museum environment, over an extended period of real time.

“The Lightfastness Correlation Project” ends in August 2011, and a final scientific report will be submitted to the sponsor, The Samuel H. Kress Foundation, in September 2011.
Research on the Corrosion of Bronze Weapons from the Pits of the Terracotta Warriors
Authors: Zhang Xiaomei , Yuan Sixun , Wu Yongqi , Guo Baofa , Han Jing
Published: September 2011

Large amounts of bronze weapons have been unearthed from the pits of the Terracotta Warriors. Though they are of the same period, their condition is quite different; some are slightly corroded; some have almost no corrosion with a gray-black or green-gray surface; some are badly corroded. ICP, XRD, SEM, EDX, XRF, AES and Metalloscope were employed on seven bronze weapons to investigate their composition, structure and differences between the surfaces and bulk metals. Results showed that all these bronze weapons are high-tin bronzes. The three bronze swords contain a higher tin content than the others and have undergone heat treatment, which gives them the necessary tenacity of weapons. The surface layers of the weapons are rich in tin in various degrees because of selective corrosion and the migration of copper ions during corrosion. Some objects are more corrosion-resistant by a quenching treatment and the formation of compact tin oxides.
Divergent Pottery Firing Practices at the Advent of the Early Bronze Age: The Social Integration of Crafts and Craftspeople at Kura-Araxes Sites in the Northeastern Caucasus
Authors: Heinsch MaryFran
Published: September 2011

Two separate pottery types, Kura-Araxes and Velikent Fine Wares can be found together at a number of Early Bronze Age sites in the Northeastern Caucasus. These ceramics are strikingly different in their appearance. Velikent Fine Ware bears indications that it may have been fired at a much higher temperature than Kura-Araxes wares. The obvious contrasts in their production raised suspicions that Velikent Fine Wares represented either an import or an intrusive production regime perhaps linked to the advent of Bronze metallurgy in this region or at least relying on a shared pyrotechnology. Prior results of Xeroradiographic analysis and INAA are merged with recent re-firing analysis to examine these hypotheses. The findings suggest that while a specific link between metal and pottery production cannot be confirmed, the emergence of divergent firing practices within an otherwise unified production tradition speaks to complex relationships between craftspeople within Early Bronze Age communities in the Caucasus.
Poly-Si Thin Film Formation Using a Novel Low Thermal Budget Process
Authors: Zhu Minghao , Kuo Yue , Lin Chen-Han , Wang Qi
Published: September 2011

Polycrystalline silicon thin films were formed from the amorphous silicon thin film by the pulsed rapid thermal annealing process enhanced with a thin nickel seed layer through the vertical crystallization mechanism. In this paper, authors presented the results on the material properties of the crystallized film. The dopant and film thickness effects were also investigated. It has been demonstrated that a 2 μm thick amorphous silicon n+-i-p+ diode structure could be transformed into polycrystalline stack with a 4-pulse 1 sec 850°C heating and 5 sec cooling cycle process.