bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Experimental Study on the Influence of Gamma Radiation on Spent Fuel Dissolution in the Presence of a H2 Atmosphere
Authors: Quiñones Javier , Cobo Jose Manuel , Huebra Ángel González de la , Esparza Aurora Martínez 
Published: April 2011

AbstractAny environmental performance assessment of spent nuclear fuel disposal requires a prediction of the spent fuel matrix alteration rate when contact with groundwater is established. Taking into account the disposal design, the groundwater at the expected depth of the repository are generally reducing. These reducing redox conditions near the spent fuel surface may be changed to oxidising conditions by the radiolysis of water, due to radiation associated with the waste. This study is focussed on determining the influence of the γ radiation on the spent fuel matrix alteration rate under simulated repository conditions. A series of sequential leaching experiments under controlled conditions have been done. The experiments simulate the repository environmental conditions when engineering barriers are degraded and groundwater arrives at the surface of the spent fuel. In these experiments SIMFUEL (SIMulated FUEL) was used as analogue of spent fuel. Two types of leachant (i.e., granitic water and bentonitic-granitic water) were used in the leaching experiments. These experiments were irradiated using γ- radiation at an industrial irradiation facility with a 60Co source. The results obtained in this study show different behaviour as a function of both the leachant used in the leaching experiments and the initial atmosphere used in the experiments. As a preliminary conclusion of this experimental work, under γ radiation and a small partial pressure of H2 (1 bar) in the first steps of the leaching process has a beneficial effect since U in solution is lower than any other conditions and overall alteration rate is minimized. For experimental times longer than one day, a clear increase of the U in solution is revealed in the experimental run products.
Investigation of magnetic properties in Mn incorporated InSb, InP, and GaAs, synthesized through controlled-ambient annealing
Authors: Hollingsworth Joel , Bandaru Prabhakar 
Published: April 2011

AbstractMagnetic semiconductors are of interest for emerging spintronic applications, such as the integration of electronic information processing with magnetic data storage. We report on a new approach - furnace annealing under controlled ambients – aimed at increasing Mn incorporation and synthesizing new magnetic semiconductors with Tc greater than/around room temperature. These annealing treatments are hypothesized to reduce the effect of Mn interstitials. We have obtained preliminary SQUID magnetometry results which indicate ferromagnetic Curie temperatures of around 130 K in (In,Mn) Sb and 60 K in (In, Mn)P. X-ray diffraction was used to characterize phase homogeneity.
Model for Spin Injection into Conjugated Organic Semiconductors
Authors: Ruden P. Paul , Smith Darryl L. 
Published: April 2011

AbstractWe present a theoretical model to describe electrical spin injection from a ferromagnetic metal contact into a conjugated organic semiconductor. To achieve significant spin current, the organic semiconductor must be driven far out of local thermal equilibrium by an electric current. Effective spin injection therefore requires that equilibration between the conjugated organic semiconductor and the metallic contact be suppressed by an energy barrier to injection that may be due either to a large Schottky barrier or to an insulating tunnel barrier. The results are compared with simulations for a silicon based device structure. Detection of the injected spin current in the organic semiconductor is also addressed.
Growth of mirror-like Zn1−xMnxO diluted magnetic semiconductor thin films by r.f. magnetron sputtering method
Authors: Lee Sejoon , Lee Hye Sung , Kim Deuk Young 
Published: April 2011

AbstractThe Zn1−xMnxO thin films were grown on Al2O3 (0001) substrates by an r.f. magnetron sputtering method. The film grown with employing buffer layer shows mirror-like surface, while the film grown without buffer layer shows the columnar-structured configuration. The mirror-like Zn0.93Mn0.07O thin films have the single crystalline phase with (000ℓ) orientation normal to the substrate surface and show the UV emission originated from the near band-edge-emission for the measurements of x-ray diffraction and photoluminescence, respectively. The mirror-like Zn0.93Mn0.07O film clearly showed a hysteresis loop, which is obvious evidence of ferromagnetism, and the Curie temperature was determined to be 68 K for the characterization of the temperature-dependent magnetization.
Electronic structure of the diluted magnetic semiconductors Pb1−xSnxTe:Yb
Authors: Skipetrov Evgenii , Zvereva Elena , Volkova Olga , Golubev Alexander , Slyn'ko Vasiliy 
Published: April 2011

AbstractThe galvanomagnetic effects in the new diluted magnetic semiconductors Pb1−xSnxTe:Yb were studied to determine the parameters of the electronic structure and to elucidate its influence on the magnetic properties. It was found that the temperature dependencies of the resistivity ρ and the Hall coefficient RH have a “metallic” character, however the RH changes in anomalous manner: its value increases more than by order of magnitude and then passes through maximum with increasing the temperature. Upon an increase of the ytterbium concentration the hole concentration decreases by more than order of magnitude. The results were explained assuming a formation of deep ytterbium-induced defect level in the valence band of the alloys, which moves up to its top with increasing the ytterbium concentration and pins the Fermi level within the valence band. The energy position of the Fermi level was calculated in the frame of two-band dispersion law and used to determine the position of Yb level in the alloys. The diagram of the charge carrier energy spectrum under varying the alloy composition was built.
DNET: The Drexel Nano Engineering Track.
Authors: Li Christopher Y. , Tenneti Kishore , Solari Dan , Zavaliangos Antonios , Kalidindi Surya , Gogotsi Yury , Sohlberg Karl , DiNardo N. John 
Published: April 2011

AbstractEarly exposure of Nanoscale Science, Engineering and Technology (NSET) to undergraduate students is anticipated to play a pivotal role in recruiting highly qualified professionals for industry and in preparing future faculty and researchers for graduate education. Focusing on early undergraduate education in NSET, the newly launched Drexel Nano Engineering Track (DNET) program at Drexel University addresses the urgent need for early NSET education at the University level. The primary objective of the DNET program is to expose freshmen and sophomores in Drexel's College of Engineering to basic concepts in NSET. It is envisioned that the career decisions of a large fraction of students will be directed as they learn the vocabulary of NSET and see potential engineering applications. The current DNET program activities include (1) updating/modifying a series of freshmen/sophomore courses / laboratories to infuse NSET into early undergraduate curriculum. Because of the size of the established tDEC program, this initiative has been able to reach a remarkably large body of students immediately. Over 700 students are enrolled in NSET-revised freshmen courses, and they will progress to NSET-revised sophomore courses the next year. (2) developing a number of modules for NSET education and (3) launching/maintaining a DNET web for information dissemination, performance assessment and outreach activities. The DNET program, together with the existing Nanotechnology Institute and Drexel/Upenn IGERT program that focus on the NSET research and graduate education, offer a stream of NSET education from college to graduate school at Drexel University.
Graduate Teaching Fellows in the Classroom: Connecting University Research and Resources to the K-12 Community
Authors: Hammer Donna , Srikantaiah Deepa 
Published: April 2011

AbstractUniversity-based education outreach efforts in the areas of science and engineering are continuing to grow and be refined as their success stories rapidly increase. As we have learned, effective outreach to K-12 schools and the broader community requires an understanding of the K-12 educational system, making a long-term commitment to support and enhance the existing curriculum, training researchers, and meeting our own goals of integrating the excitement of new science and technology into the classroom.The University of Maryland (UMD) Materials Research Science and Engineering Center (MRSEC) Graduate Teaching Fellows Program (GK-12) is making strides to accomplish these objectives. This paper will be a descriptive overview of the of the UMD GK-12 Program. Emphasis will be placed on the importance of developing viable partnerships, integrating research-based concepts into the curriculum (emphasizing materials science related topics), and training research Fellows to develop the necessary skills to take advantage of their research background and to refine their teaching and communication skills within the scope of informal science and engineering education.
Incorporating Diverse Majors and Backgrounds in Materials Science Research Experience for Undergraduates (REU) Sites
Authors: Bahr D.F. , Norton M.G. 
Published: April 2011

AbstractA summer Research Experience for Undergraduate (REU) site program has been operating at Washington State University for the past five summers. Over this time we have experimented with several modes of organized summer research methods, including students working in individual projects as well as students working in teams. We have balanced the academic standing of the students (freshmen to seniors), as well providing a diverse demographic background. The results of these past five summers will be presented, as well as recommendations for which methods have been the most successful in terms of generating publications and presentations from the students as well as the likelihood of students entering graduate school.
Organically Hybridized In2O3 Thin Film Gas Sensors
Authors: Matsubara Ichiro , Murayama Norimitsu , Shin Woosuck , Izu Noriya 
Published: April 2011

ABSTRACTOrganically hybridized In2O3 thin films have been prepared. The surface of In2O3 thin films was hybridized by organic components with various kinds of functional groups. Upon exposure to CO gas, the electrical resistance of the hybrid sensor with amino group in the organic components increased (R-increasing response), whereas H2 gas caused the decreasing in the sensor resistance. No response was obtained to CH4 gas. For the n-type metal oxide semiconductors, the R-increasing response cannot be explained by the ordinary combustion mechanism. The response of R-increasing or R-decreasing to CO was controlled by functional groups of organic components as in the case of SnO2-based hybrid thin films. The approach of organic-inorganic hybridization is effective to realize the selective detection of reducing gas molecules.
Nano-Design of Oxide Particles and Electrode Structure for High Sensitivity NO2 Sensor Using WO3 Thick Film
Authors: Tamaki Jun 
Published: April 2011

ABSTRACTNovel sensor design for high sensitivity gas sensors has been proposed for the detection of dilute NO2 using WO3 film. First, concerning nano-design of oxide particles, the disk-shaped WO3 particles (300 nm in diameter, 20 nm in thickness) were deposited on Au comb-type microelectrode (line width: 5 μm, distance between lines: 5 μm) to be WO3 thick film sensor. This sensor showed the excellent sensing properties to dilute NO2 at optimized thickness. Second, the nano-gap electrode with various gap-sizes (110–1500 nm) was fabricated by means of MEMS techniques in order to investigate the effect of microelectrode. When the gap size was decreased less than 800 nm, the sensitivity to dilute NO2 increased with decreasing gap size. This was understood from the facts that the contribution of interface resistance between particle and electrode to total sensor resistance was increased and that the sensitivity at electrode-grain interface was much larger than that at grain boundary. It was found that the designs of not only nano-particles but also nano-electrode were important for the fabrication of high sensitivity gas sensor.
Sensitive, Selective, & Tunable Porous Silicon Gas Sensor
Authors: Lewis Stephen , Gole James , Hesketh Peter J. 
Published: April 2011

ABSTRACTHybrid porous silicon, consisting of a microporous framework whose walls are covered with a thin nanoporous layer, proves to be an inexpensive and robust platform for fabrication of rapid, reversible, and sensitive semiconductor sensors. An extremely high surface area provides a mechanism for the detection of ppm and ppb levels of a range of gases including ammonia, NOx, and CO. A general method of coating electroless metal onto the surface provides a basis for nanostructure induced selectivity between these gases. Further, the introduction of FFT analysis to the rapidly reversible and linear response of the porous silicon gas sensor allows the gas response to be acquired and filtered on a drifting baseline.
Sub-micron structured Metal Oxide gas sensors by means of lithographic techniques
Authors: Candeloro Patrizio , Baratto Camilla , Comini Elisabetta , Faglia Guido , Di Fabrizio Enzo M. , Sberveglieri Giorgio 
Published: April 2011

ABSTRACTIn this work we employed lithographic techniques, combined with sputtering depositions, to fabricate semiconductor metal-oxide (MOX) gas sensors with controlled grain dimensions. The basic idea is to replace the continuous sensing film of standard MOX sensors with a pattern of wires in the sub-micron scale, thus controlling the lateral size of the grains. Regarding the fabrication process, we followed two different approaches: a plain lift-off technique and a substrate patterning process. We present a comparison between the results of both the approaches. Furthermore, we tested the electrical responses to several gases and compared them with those of continuous film sensors. The experimental data highlight an improvement for the patterned sensors.
Resistive Oxygen Gas Sensors Using Cerium Oxide Nanosized Powder
Authors: Murayama Norimitsu , Izu Noriya , Shin Woosuck , Matsubara Ichiro 
Published: April 2011

ABSTRACTCerium oxide nanosized powder was synthesized by modified precipitation method. The precipitate, which was formed from the addition of NH4OH to Ce(NO3)3 aqueous solution, and was filtered. The obtained gel was mixed with carbon powder with a particle size of about 20 nm by a mechanically rotating mixer. The mixture was dried at 343 K in air. The carbon powder was burned out by heat treatment at 1173 K in air for 4 h, resulting in the formation of CeO2 powder with a size of 50 nm. A thick film was formed on an alumina substrate by screen printing, and was fired at 1373 K. The thick film had porous structure and the grain size was about 120 nm. The resistance of the thick film was almost proportional to P (O2)1/6, where P (O2) is oxygen partial pressure, in the P (O2) range from 10−13 to 105 Pa at 1073 and 1173 K. The response time (t90) was 23 and 7 ms at 1023 K when P(O2) changed from 65 to 25 kPa and 25 to 65 kPa, respectively. The reason for this result was explained on the basis of surface reaction of cerium oxide grain.
HRTEM/EELS Analysis, Structural Characterization and Sensor Performances of Hydrothermal Nano-TiO2
Authors: Ruiz Ana M. , Arbiol J. , Cornet A. , Shimanoe K. , Morante Joan R. , Yamazoe N. 
Published: April 2011

ABSTRACTPure nanophased TiO2 with controlled microstructure and resistant to thermal induced grain growth has been prepared by hydrothermal treatments. The synthesized nano-TiO2 presents small size and well defined and faceted surface, as shown by Raman spectroscopy, XRD, EELS and HRTEM. Such performances are slightly changed with the posterior temperature treatments up to 700 °C, maintaining anatase phase structure and grain size about 20nm. The extent of stabilization depended on the pH of the treatment, being pH 2 more convenient for stabilizing the size, and pH 3 for the phase. HRTEM and EELS measurements showed the coexistence of rutile big particles (∼100 nm) with anatase small particles (∼40 nm) at pH 3 and calcination at 900°C. Thick-films of precipitated TiO2 and hydrothermally treated TiO2 were tested for the CO and the ethanol response. The hydrothermal treatment allowed obtaining stable sensitive films which exhibited enlarged sensor response and improved transients, specially in the case of the materials treated at pH 3.
Environmental Sensitivity of Pentacene Thin-Film Transistors
Authors: Breban M. , Mezhenny S. , Hines D. R. , Romero D. B. , Ballarotto V. W. , Williams E. D. 
Published: April 2011

ABSTRACTBy alternating the gate voltage polarity of a pentacene thin film transistor, we show that the drain current is stabilized and thus the bias stress effect is overcome. This allows for controlled testing of the device sensitivity to environmental conditions. We find that the conductivity of the device decreases on the time scale of seconds when the device is exposed to water vapor, which is manifested through a decrease in mobility and a shift in the threshold voltage. Simple recombination modeling suggests that trapping is the responsible mechanism. However, the effects of water vapor can be reversed by exposing the device to dry nitrogen flow. The time scale for recovery is on the order of 10s of minutes.
Sensing Mechanism of NO in Nanocrystalline Ru, Pt, Pd-Doped SnO2: Electron Paramagnetic Resonance, Mössbauer and Electrical Study
Authors: Canevali Carmen , Maria Mari Claudio , Mattoni Mariachiara , Morazzoni Franca , Ruffo Riccardo , Scotti Roberto , Russo Umberto , Nodari Luca 
Published: April 2011

ABSTRACTThe reactivity of nanosized Ru(Pd,Pt)-doped SnO2, obtained by sol-gel synthesis, towards NO/Ar was investigated by Electron Paramagnetic Resonance (EPR), Mössbauer and Electrical Resistance measurements. A sensing mechanism was proposed that involves (i) the formation of bielectronic oxygen vacancies VO, (ii) their single-ionisation to VO•, which injects electrons to SnO2 conduction band, (iii) the transfer of VO• electrons to the transition metal centers reducing them to lower oxidation states. It was suggested that the electronic exchange between oxide and transition metal is responsible for the enhancement of the reactivity in doped SnO2 with respect to the undoped material.
Printed Organic Electronic Devices Made using High Volume Printing Processes
Authors: Xia Yu , Karwa Anupama , Sigg Franz , Clark Daniel M. , Kahn Bruce E. 
Published: April 2011

ABSTRACTPrinting is a promising technique to fabricate commercial organic electronic devices such as OLED, TFT, solar cells and sensors. In this investigation, we report the application of high volume flexographic printing, which makes low cost and batch production possible. Commercial RFID tags have been printed using metallic inks with organic compounds in the Printing Applications Lab (PAL) at Rochester Institute of Technology (RIT). Polyaniline ink was prepared and printed by flexography in the form of test targets and Interdigitated electrodes (IDE). The conductivity can be controlled by different levels of doping. Furthermore, multiple impression printing was used to print overlapping functional layers to obtain all printed organic electronic devices like chemical vapor and humidity sensors. Optical profilometry and SEM were used to analyze the surface and interface structure. Sensitivity was measured and compared with commercial devices.
Encapsulation of Urease in Molybdenum Trioxide Sol-Gel
Authors: Jha Prashant K. , Gouma P. I. 
Published: April 2011

ABSTRACTMolybdenum trioxide sol-gel matrices were tested for their ability to host biomaterials in their structures without adversely affecting the activity of the encapsulated biomolecules. The sol-gel composites were prepared at room temperature; the urease was added during the hydrolysis step to ensure proper encapsulation in the pore structure of the sol. Phosphate buffer solution was added during this stage to maintain the pH value of the sol in the bio-compatible range. The activity of incorporated urease was tested by exposing composite sol-gel material to standard urea test solutions and measuring the amount of gaseous ammonia (released by the reaction of urea with water in the presence of urease) using an ammonia electrode. The concentration of urea solutions ranged from 1mM to 10mM. An electronic olfactory system (EOS 835) was also employed to detect the presence of gaseous ammonia. Gas sensing tests were done to verify the sensitivity of the matrix to ammonia. Microstructural analysis was carried out by means of scanning and transmission electron microscopy. It was found that urease retained its activity inside molybdenum trioxide sol-gels that are sensitive to ammonia. These hybrid nanoporous composites are useful in the field of biosensors and fuel cells.
Low Voltage and High Speed Silicon Nanocrystal Memories
Authors: Carreras Josep , Garrido B. , Arbiol J. , Morante J. R. 
Published: April 2011

ABSTRACTWe have studied a set of MOS cell structures with 30 nm thick thermal oxide implanted with Si at high doses (10, 15 and 20 atomic % at projected range) in which Si nanocrystals (Si-nc) have been precipitated by annealing at 1100 °C. Energy filtered transmission electron microscopy reveals: i) a central layer of Si-nc with a mean size of 2.8 nm; ii) a control oxide of 12.5 nm completely free of Si-nc and iii) a tunnel oxide of about 2.5 nm. This narrow tunnel oxide enables the direct tunnel for charging and discharging which is a must for high speed and good reliability. However, this results in typical retention times ranging from only few hours to several months, depending on the concentration of Si-nc. For developing low voltage memories we have focused on the highest Si excess sample, which shows fast write times (tens of μs) at very low gate fields (±2 MV/cm or ±6V). The onset of Fowler-Nordheim conduction is of about ±6 MV/cm by J-V measurements (±18V), which means that the structure works in a direct tunnel regime. To increase the retention time we have performed an additional annealing step in diluted O2 for 16 and 32 minutes, resulting in a dramatic increase in the retention times, which is attributed to the re-growth of an additional tunnel oxide which eliminates surface roughness, remaining Si excess and defects at the Si-SiO2 interface. This additional oxidation step produces also a decrease in the mean size of the Si-nc distribution. Thus, we increase the retention time beyond the 10 years standard limit. Finally, the writing times can be traded-off by increasing slightly the program voltage up to ±2.7 MV/cm or ±8V.