bluuebunny/crossref_metadata_2025 huggingface dataset:
Advantages of high surface area niobium oxide catalysts on MgH2 sorption properties
Authors: Bhat Vinay V , Rougier Aline , Aymard Luc , Nazri Gholam A , Tarascon Jean-Marie
Published: April 2011

We report the synthesis by ‘chimie douce’ route of high surface area (200 m2/g) nano crystalline Nb2O5 (so called p-Nb2O5) and the importance of its addition to enhance the hydrogen sorption properties of MgH2. All of the prepared Nb2O5 catalysts induce faster kinetics, up to twice the desorption rate, than commonly used commercial Nb2O5. Among them, both p-Nb2O5 and Nb2O5:350 (p-Nb2O5 heated to 350 °C) exhibit the best catalytic activity, since a 5.2 wt% hydrogen desorption was achieved at 300 °C for (MgH2)p−Nb2O5, as compared to less than 4 wt.% for commercial Nb2O5 added MgH2, (MgH2)c−Nb2O5, within 12 min. Furthermore, due to the addition of high surface area Nb2O5, the desorption temperature was successfully lowered down to 200 °C, with a significant amount of desorbed hydrogen (4.5 wt%). In contrast at this “low” temperature, (MgH2)c−Nb2O5 shows no desorption.
Capillary Densification of Hydrogen in Nanoporous, Amorphous Carbons
Authors: Lustig Steven R. , Shiflett Mark , Corbin David , Gai Pratibha , Kourtakis Konstantinos
Published: April 2011

We have studied the effect of synthesis conditions on the nanostructure of advanced carbons that show moderate to high hydrogen storage. We have performed in situ studies of the dynamic pyrolysis of palladium catalyzed multifunctional polymers (MFP) in nitrogen environments, to understand the effect of process parameters and to utilize the results in the development of optimum nanostructures to meet the storage requirements. Carbon sorbents have been synthesized from polysaccharides including chitosan, chitin, and cellulose. Pyrolysis in a hydrogen atmosphere at 1373 K and 24 h has lead to microporous carbons with an optimum surface area and pore volume exceeding 2000 m2 g−1 and 2.0 cc g−1, respectively. Gravimetric microbalance studies indicate that these materials physically absorb hydrogen and store between 7 to 10 mass percent at 10 bar and 100 K. TEM micrographs indicate that the amorphous carbon shows additional ordering with prolonged hydrogen treatment from 2 to 24 h which has proven beneficial in increasing hydrogen storage. X-ray diffraction, TEM analysis, and porosimetry measurements also indicate that extending hydrogen exposure beyond 24 h leads to decreasing hydrogen storage due to the continuation of a loss in carbon relative to metal contaminants (P, Ca, Na) in the starting materials and increased crystallinity. Comparison of the results have shown that for advanced carbons derived from polymers or natural products treated with hydrogen at high temperatures, the optimum nanostructure is substantially disordered (turbostratic) graphite, whereas for materials derived from MFP, it is primarily amorphous carbon. The experiments have also revealed the optimum temperature region for storage where sorption/desorption curves show evidence of capillary condensation/densification.
The Inclusion of Hydrogen in Clathrate Hydrates of the Various Guests and Tuning of the tert-Butylamine Hydrate
Authors: Lee Huen , Lee Jong-won , Kim Do Youn , Park Jeasung
Published: April 2011

Clathrate hydrates of structure II with organic cyclic oxides were identified to have the ability to include molecular hydrogen into their empty small cages at near-ambient temperature and moderate pressure. Solid-state NMR and Raman spectroscopy of the included hydrogen molecules indicate that the small cavities are both singly and doubly occupied by hydrogen molecules in the mixed hydrates. The inclusion mechanism can be derived from the critical progression of the cage occupancies as determined from in-situ kinetic experiments on formation and decomposition. The inclusion ability of hydrogen molecules was observed for several organic clathrate hydrate formers such as THF (tetrahydrofuran) and 1,4-dioxane, suggesting this to be a general property. A structural transition of the simple amine hydrate was suggested to produce a novel double CH4 + t-BuNH2 hydrate as confirmed by using microscopic analytical methods. The corresponding hydrate compositions were determined by using NMR spectroscopy to describe a tuning mechanism to increase the storage capacity.
Phonon modes, dielectric constants, and exciton mass parameters in ternary MgxZn1−xO
Authors: Bundesmann Carsten , Lorenz Michael , Grundmann Marius , Schubert Mathias
Published: April 2011

The long-wavelength optical phonons and dielectric constants of PLD-grown MgxZn1−xO films are studied by combination of infrared spectroscopic ellipsometry and Raman scattering spectroscopy. The ternary alloy MgxZn1−xO exhibits a phase transition with change of coordination number from four-fold coordinated, hexagonal wurtzite structure (ZnO) to six-fold coordinated, cubic rocksalt structure (MgO). It is found that both phonon mode frequencies and dielectric constants change abruptly upon phase transition, which is assigned to the change of coordination number. The change of dielectric constants can be related to the change of electronic properties, for instance, the exciton binding energy. In a simple approach, the exciton binding energy depends on the reduced exciton mass and the static dielectric constant. By comparison with experimental values of the exciton binding energies it is found that the reduced exciton mass must increase by a factor of about two upon face transition from wurtzite to rocksalt structure.
Vapor-Phase Functionalization of Nanostructured Gradient-Index Titanium Dioxide Thin Films
Authors: van Popta Andy C. , Steele John J. , Tsoi Shufen , Fok Enrico , Veinot Jonathan G. C. , Brett Michael J. , Sit Jeremy C.
Published: April 2011

Chemical treatments, when applied to nanostructured oxide thin films, can be used to generate added functionality in many devices. In this study, a nanostructured defect-mode optical filter was prepared by glancing angle deposition of titanium dioxide and functionalized with 3,3,3-trifluoropropyl-trichlorosilane to render the thin film insensitive to variable humidity conditions. Electrical characterization and contact angle measurements demonstrate that the hydrophilic thin film becomes hydrophobic when functionalized, and transmission measurements clearly show that the wavelength shift of the defect-mode becomes strongly inhibited for a wide range of humidity levels.
Structuring of Low Firing Temperature PZT Thick Films by Photolithography
Authors: Schimpf Stefan , Schmidt Bertram
Published: April 2011

Structured piezoelectric PZT thick films were fabricated on silicon wafers. Different supplements, like lead oxide and glasses, were added to the PZT to enhance the sintering. The films were structured by doctor blading on an epoxy based photoresist mask. This allows very accurate micro patterns of high quality piezoelectric material. A firing process was developed to gain PZT structures with 200 μm in lateral size and a 200 μm pitch. The structures were electrically contacted, poled and characterized.
Studies of Interfacial Optical and Electrical Properties on Transparent Dielectrics/ZnO Systems
Authors: Wang Ran Shi , An Jin , Ong H.C.
Published: April 2011

Transparent conducting oxides (TCOs) have recently attracted considerable attention due to their potential in making "invisible electronic circuits". Among different TCOs, ZnO is probably one of the most promising candidates due to its desirable optical and electrical properties. In the transistor, metal and metal-dielectric in general are used as the gate on the active channel layer to control the flow of carriers. In order to obtain high mobility, the interface between the gate and ZnO must be well controlled so that the unwanted surface recombination can be minimized. Although studies of metal/ZnO have been well documented, only a few are seen on metal/dielectric/ZnO. Here, we report a systematic study on AlOx/ZnO and MgOx/ZnO interfaces for the potential use on transistor. From previous optical measurements, both the photoluminescence (PL) and cathodoluminescence (CL) show that the cap layers improves the emission characteristics of ZnO by enhancing the band-edge emission while at the same time reducing the unwanted deep-level emissions [K.C. Hui, H.C. Ong, P.F. Lee, J.Y. Dai, Appl. Phys. Lett. 86, 152116 (2005)]. On the contrary, in this study, we find post-thermal annealing of AlOx/ZnO and MgOx/ZnO gradually degrades the emission as well as charge transport properties, which indicates defects evolve upon annealing. By using secondary ion mass spectroscopy (SIMS), we elucidate out-diffusion of Zn into the oxide layer is the root cause of degrading the optical and electrical properties of oxide/ZnO.
Preparation and Characterization of Solid Oxide Fuel Cells Cathode Films
Authors: Baqué Laura , Serquis Adriana , Grunbaum Nicolás , Prado Fernando , Caneiro Alberto
Published: April 2011

Perovskite oxide cobaltites with composition La0.4Sr0.6Co0.8Fe0.2O3 have been prepared by an acetic acid-based gel route. Then, cathodes were deposited onto porous ceramic substrates, like the usual electrolytes Cerium Gadolinium Oxide (CGO), by spray, spin coating and dip-coating. The structure and morphology of the layers were characterized by XRD and SEM, respectively. Electrical properties are characterized by complex impedance measurements. Finally, the correlation between structural characteristics and electrical properties is discussed.
The Mexican Cactus as a New Environmentally Benign Material for the Removal of Contaminants in Drinking Water
Authors: Young Kevin Andrew , Anzalone Alessandro , Pichler Thomas , Picquart Michel , Alcantar Norma A.
Published: April 2011

The use of natural environmentally benign agents in the treatment of drinking water is rapidly gaining interest due to their inherently renewable character and low toxicity. We show that the common Mexican cactus produces a gum-like substance, cactus mucilage, which shows excellent flocculating abilities and is an economically viable alternative for low-income communities. Cactus mucilage is a neutral mixture of approximately 55 high-molecular weight sugar residues composed basically of arabinose, galactose, rhamnose, xylose, and galacturonic acid. We show how this natural product was characterized for its use as a flocculating agent. Our results show the mucilage efficiency for reducing arsenic and particulates from drinking water as determined by light scattering, Atomic Absorption and Hydride Generation-Atomic Fluorescence Spectroscopy. Flocculation studies proved the mucilage to be a much faster flocculating agent when compared to Al2(SO4)3 with the efficiency increasing with mucilage concentration. Jar tests revealed that lower concentrations of mucilage provided the optimal effectiveness for supernatant clarity, an important factor in determining the potability of water. Initial filter results with the mucilage embedded in a silica matrix prove the feasibility of applying this technology as a method for heavy metal removal. This project provides fundamental, quantitative insights into the necessary and minimum requirements for natural flocculating agents that are innovative, environmentally benign, and cost-effective.
Adsorption of Heavy Metals and Organic Contaminants on Functionalized Periodic Mesoporous Organosilicates
Authors: Ding Fengling , Ingram Conrad
Published: April 2011

Mesoporous organosilicates containing an ethylene bridge within the otherwise silicate pore walls and an additional organic functionality extended within the pore showed varying adsorption capacities for mercury and dimethylphenol. Thiol and imidazole functionalized organic-inorganic materials were effective for the adsorption of mercury, whereas the purely siliceous mesoporous MCM-41 was more effective for dimethylphenol adsorption than its organosilicate counterparts.
Visible-Light Inactivation of Escherichia Coli on N-Doped Titanium Oxide Thin Films
Authors: Wu Pinggui , Shang JianKu
Published: April 2011

Antimicrobial behavior of nitrogen-doped titanium dioxide (TiON) thin films was examined by cell viability assays under visible light illumination, using Escherichia coli as the indicator. The nitrogen doping was found to enable visible-light inactivation of Escherichia coli on titanium oxide films. At a light intensity of 1.6 mW/cm2, TiON films reached a bacterial killing rate of about 50% in half an hour, comparable to those reported for ultraviolet light irradiated TiO2. In the range of nitrogen concentrations from 0.2 to 0.9, the bacterial killing rates showed no clear correlation with the nitrogen concentration for the TiON films.
A “Bottom-Up” Approach to Engineering Education in Nanotechnology
Authors: Lee Sang-Joon John , Allen Emily L. , He Lili
Published: April 2011

This paper presents a pilot project for a “bottom-up” approach to reform of undergraduate engineering education in nanotechnology, supported by a planning grant from the National Science Foundation (Engineering Education and Centers, Award #0431970). A core principle is to have individuals from different disciplines be the ones not only to build concise modules, but also to share them with content developers in other disciplines under a common organized framework. This bottom-up approach is an efficient way of introducing new content in existing curricula, and is especially helpful in university environments that may have no comprehensive “experts” in nanotechnology per se. Having individuals work together to develop bottom-up pieces from their own specialized fields provides a mechanism not only for curriculum enhancement but also for faculty professional development. In this work, pilot modules are developed as new content infused into existing courses in mechanical engineering, electrical engineering, and materials engineering at San José State University. Topics span different aspects of nanoscale materials, phenomena, devices, and manufacturing, and the content is structured in a framework such that components may be packaged as modular entities. We present pilot work accomplished in this work-in-progress, with emphasis on how lessons learned can be applied to expandability and sustainability of this bottom-up approach.
Nanoscience, Nanoengineering and Nanotechnology Education at Colorado State University - Pueblo
Authors: Jaksic Nebojsa
Published: April 2011

This work reports on the evolution of nanoscience, nanoengineering and nanotechnology (NSET) education in the Engineering Department at the Colorado State University – Pueblo (CSU-Pueblo) from 2002 to 2006. It includes both, undergraduate and graduate courses with NSET topics as well as a review of undergraduate and graduate research projects.
Efforts to Implement a PhD degree program in “Nanoscale Science” at UNC Charlotte
Authors: Poler Jordan , Donovan-Merkert Bernadette T. , Davies Angela , El-Kouedi Mahnaz , Krueger Joanna , Smith Stuart , Stokes Edward , Schmedake Thomas A.
Published: April 2011

UNC Charlotte is a young and growing research university. Most of the Ph.D. programs on our campus have been designed to be interdisciplinary. This strategic choice was made for both economic and pedagogical reasons. At the heart of the drive for interdisciplinary degree programs is the recognition that a lack of educational diversity at the Ph.D. level is limiting for new graduates in today's research and discovery landscape. This need for educational diversity is even more acute in the sciences. We need more chemists that know more physics, and we need more physicists that know more biology, and we need more engineers that understand matter at a molecular scale.

To this end, faculty in the departments of chemistry, optical sciences, mechanical engineering, and electrical engineering have designed and are implementing a new interdisciplinary Ph.D. degree in “Nanoscale Science”. Research involving nanoscale materials and phenomena requires an educational perspective far broader than traditional academic disciplines currently offer. The question is how to deliver a broad graduate education that enables each student to reach an expertise required for the Ph.D. This is the question that has driven our pedagogical development of this Nanoscale science program.

The overall structure of this program will be described and compared to other current efforts in Nanoscale graduate education throughout the United States. Various novel features will be discussed, with the hope for critical feedback and discussion. Details of the educational opportunities we have designed and the method of assessment we will employ will be presented.
The Interfacial Layer between Pt/PCMO and the Bi-stable Resistive States
Authors: Pan Wei , Evans David Russell
Published: April 2011

Nobel metals in contact with perovskite metal oxides, Pr1−xCaxMnO3 (PCMO) for example, have shown switching resistance values, with a couple of orders of magnitude difference, upon the stimulation of electrical pulses. In this paper, the Pt/PCMO/Pt structures were made through e-beam evaporation (Pt electrodes) and RF sputtering (PCMO films) for the switching mechanism study. Specially designed experiments along with extensive electrical characterizations were performed on the Pt/PCMO/Pt structure. The existence of a contact resistance, or an interfacial layer, between Pt electrodes and PCMO was evident by simply measuring initial resistance (R0) of the stack against PMCO film thickness. Temperature dependence of the R0 and the time-bias tests were used to study the transport mechanism in the bulk of PCMO and the interfacial layer. Above a threshold voltage, the transport changes from mainly electronic to ionic conduction especially at the interfaces, causing electrode polarization. The transient characteristics of Pt/PCMO/Pt stack, i.e. the response to the pulsing in the time domain, were characterized in the frequency domain instead through the admittance spectroscopy measurements. The temperature dependence of Cole-Cole plots were used to study the polarized interfacial layer or interface dipole polarization (IDP). This IDP layer is the origin of contact resistance and also responsible for the uni-polar long-short switching because the calculated relaxation time constants of the IDP corresponding to low resistive state (LRS) and high resistive state (HRS) were similar to the experimental values. Therefore, the so-called bi-stable resistive states are just two different IDP states: one is much leakier than the other.
Preparation of Perovskite Conductive LaNiO3 Films by Sol-Gel Techniques
Authors: Lai Pei-Ying , Chen Jen-Sue
Published: April 2011

Metallic thin films of LaNiO3 (LNO) have been prepared by the sol-gel method using lanthanum nitrate [La(NO3)3·6H2O] and nickel acetate [Ni(CH3COO)2·4H2O] as raw materials. X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and electrical measurements were used to characterize the multilayer LNO thin films. The perovskite phase appears after annealing at temperatures above 600 °C. LNO thin films are n-type metallic oxide. The lowest resistivity is 621 °Ω-cm after annealing at 600 °C, and the carrier concentration is 6.09×1022/cm3.
Plasma Synthesis and Surface Passivation of Silicon Quantum Dots with Photoluminescence Quantum Yields higher than 60%
Authors: Mangolini Lorenzo , Jurbergs David , Rogojina Elena , Kortshagen Uwe
Published: April 2011

Silicon nanocrystals with diameters of less than 5 nm show efficient room temperature pho-toluminescence (PL). Previous reports of PL quantum yields for ensembles of silicon quantum dots have usually been in the few percent range, and generally less than 30%. Here we report the plasma synthesis of silicon quantum dots and their subsequent wet-chemical surface passivation with organic ligands while strictly excluding oxygen. Photoluminescence quantum yields as high as 62% have been achieved at peak wavelengths of about 789 nm.
Metal-Insulator Phase Transition in VO2: A Look from the Far Infrared Side
Authors: Jepsen Peter Uhd , Fischer Bernd M. , Thoman Andreas , Helm Hanspeter , Suh J. Y. , Lopez Rene , Hanglund Richard F.
Published: April 2011

Vanadium dioxide (VO2) displays a well-known metal-insulator (MI) transition at a temperature of 68°C. In this study we use terahertz time-domain spectroscopy (THz-TDS) to investigate the optical properties of VO2 thin films in the vicinity of the MI transition temperature in the frequency range 0.1 – 1.5 THz. We observe the interesting effect that the phase of the transmitted THz field through the conducting VO2 film is delayed in comparison to the phase of the same THz signal transmitted through the insulating VO2 film. This is in contrast to the expected behavior of a homogeneous, conducting film. This observation shows that even at temperatures significantly above the transition temperature, the formation of a homogeneous, conducting film is incomplete. We demonstrate that effective-medium theory (EMT) in combination with a Drude model accounting for the conductivity of metallic domains formed in the VO2 film accounts for all our observations. We show that the Maxwell-Garnett EMT is consistent with our observations, whereas the Bruggeman EMT fails to account for our observations.
Generation of Strong Short Terahertz Pulses via Stimulated Raman Adiabatic Passage-assisted Coherent Scattering
Authors: Kalugin Nikolai , Rostovtsev Yuri , Scully Marlan O.
Published: April 2011

We analyzed the efficiency of coherent scattering of infrared radiation in atomic and molecular gases for production of intense short THz pulses, using simulated Raman adiabatic passage (STIRAP). The method is based on excitation of maximal coherence when the system is undergoing through STIRAP in IR-irradiated atomic or molecular gases (for example Rb, methanol, and others) at room temperature. By applying optical pulses in correct sequence one can generate coherence in a system during STIRAP which triggers following coherent scattering of infra-red radiation, and can produce pulses of THz radiation with pulse energies ranging from several nJ to µ-J and pulse durations from several fs to ns.
Spin-on Gate Dielectric Materials for Next Generation Display Systems
Authors: Chen Jinghong , Stifanos Mehari , Nedbal Jan , Krishnamoorthy Ahila , Brouk Emma , Smith Pete , Daniels Brian
Published: April 2011

We present recent advances on spin-on polymers as gate dielectric for thin film transistors. We have developed film type I with significantly improved dielectric properties. At a curing temperature of 250 °C, the dielectric constant is 3.46, the breakdown voltage is 4.10 MV/cm at 1 μA/cm2, the leakage current is 4.9 × 10−8 A/cm2 at 2.5 MV/cm, and the CV hysteresis is 3.4 V. At a curing temperature of 425 °C, the dielectric constant, the breakdown voltage, the leakage current, and the CV hysteresis are 3.2, 4.73 MV/cm, 2.6 × 10−8 A/cm2, and 0.44 V respectively.
Transport Properties of Stretch-Oriented PPV Films
Authors: Wilson Tiffany , Doty F. Patrick , Chinn Douglas , Talin A. Alec , King Michael , Hunter Luke L. , Jones Frank E. , Cuppoletti Christine , Rouchanian H. , Munoz C.
Published: April 2011

Organic semiconductors are under investigation for radiation sensors at Sandia National Laboratories. The wide band gaps, high resistivities, low dielectric constants, and high dielectric strengths of conjugated polymers suggest these materials may be suitable for solid-state particle counting detectors. A range of solution cast materials have been evaluated for this application, including polythiophenes and poly(p-phenylene vinylene)s, or PPVs.

Films were prepared by novel solution casting and mechanical stretching methods. Device structures including interdigital metal electrodes on glass and thin film transistors on SiO2 on silicon were fabricated by drop casting from solution and lamination of solid films. Transient and DC responses were recorded and analyzed. Experiments include laser stimulus for photoconductive pulse response, and field effect transistor testing. Mechanical stretching was shown to dramatically alter electrical properties of polymer films.

Future work will analyze the feasibility of single particle detection and analyze various geometries for optimization. The effects of traps and methods for reduction of trapping effects will be analyzed.
Synthesis and Characterization of Dendritic Architecture Containing Push-Pull Conjugated Organic Chromophore Possessing Nonlinear Optical Property
Authors: Choi Jin Joo , Lim Jong Sun , Lee Changjin , Kim Dong Wook
Published: April 2011

We designed and synthesized a dendritic architecture in which three branches of the NLO-active component consisting of push-pull type conjugated structure were linked onto its core. Chemical structure of the dendritic nonlinear optical (NLO) chromophore was verified by NMR spectroscopy, which clearly showed that the conjugated bridge had a trans-conformation. The dendrimer exhibited that the broad absorption band centered at around 608 nm extending to 760 nm. It was thermally stable up to 275 °C in the nitrogen atmosphere. Polymer film was prepared by spincoating the solution of mixture of amorphous polycarbonate (APC) and the dendritic chromophore, which exhibited an electro-optic coefficient of 19 pm/V at 1.55 μm wavelength.
Flexible Polymer Thin-Film Transistor Device Structures And Processes For 13.56 MHz RF Rectifier Circuits
Authors: Mohapatra Siddharth , Rotzoll Robert , Jenkins Patrick , Olariu Viorel , Grigas Michelle , Wenz Robert , Dimmler Klaus , Dodabalapur Ananth
Published: April 2011

Polymeric thin-film transistors (TFTs) have been proposed for several applications including displays, electronic paper, chemical sensors, and radio-frequency identification (RFID) tags. One important technical hurdle that has to be overcome for using organic transistors in RFID tags is for these devices to operate at RF frequencies (typically 13.56 MHz) in the front end. It was long thought that conjugated polymer transistors are too slow for this. In this presentation we will demonstrate that polymer transistor based full-wave rectifier circuits utilizing a polythiophene, a p-channel semiconductor, can operate at this frequency with a useful efficiency. In order to achieve such high-frequency operation, we make use of the non-quasi static (NQS) state of the transistors. Bottom gate and top gate structures are explored and a comparison is made between the observed electrical properties. These circuits are fabricated on PEN (polyethylenenapthalate) or PET (polyethylene-terepthalate) substrates using a spin on dielectric. Gate, source and drain contacts are defined photolithographically using evaporated gold as the metal. Field-effect mobilities in the range of 0.02 and 0.2 cm2/Vs that equal or exceed the highest reported among the ones employing similar geometries on plastic substrates are easily obtained in these systems. In order for NQS based rectification to take place the carrier velocity in a 2 micrometer channel length device needs to be more than 2×104 cm/s. This would correspond to a mobility of 0.1cm2/V-s at a field of 105 V/cm. The rectifiers were based on a 4-transistor full-wave design. A coil (transformer secondary) drives the AC inputs in differential mode. The lower diode connected transistors in a manner similar to the half-wave rectifier define the DC voltage level of the two AC input signals. The two upper transistors are connected as switches and are used to move current from the AC inputs to the positive DC output. The capacitor is used to hold the peak voltage level supplied by the coil through the switch-connected devices. The voltage rectification efficiency is relatively high being as much as 45% at 13.56 MHz. This is among the fastest polymer transistor circuit of any kind demonstrated to date.
A WORM-Type Memory Device with Rectifying Effect Based on a Conjugated Copolymer of PF6Eu on Si Substrate
Authors: Tan Yoke Ping , Ling Q.D , Teo Eric Y.H , Song Y. , Lim S.L , Patrick G.Q Lo , Kang E. T , Zhu Chunxiang , Chan D.S.H
Published: April 2011

We report a non-volatile, write-once-read-many times (WORM) memory device based on a simple organic-inorganic heterojunction. The organic film used is 9, 9-dihexylfluorene and Eu-complexed benzoate (PF6Eu (DBM)), which contains both electron-donor (9, 9-dihexylfluorene) and electron-acceptor (europium complex) groups. The inorganic n-type silicon substrate is used as the bottom electrode, while the Al is used as the top electrode. Under current-voltage testing, the device is able to switch from one initial non-conducting state (OFF) to a conducting state (ON) once a threshold voltage is reached under the first positive sweep. The “OFF” state is not recoverable with subsequent negative sweep after the device is turned “ON”. The ON/OFF current ratio is around 4×104. Diode rectifying characteristics is also observed for the turned-on device with a current ratio of 7×104, which is essential to address one memory cell in large passive matrix circuits. Reliability test is carried out and the device is able to sustain its “ON” state for at least 12 hours without any external bias.
A New Top Gate Pentacene Organic Thin Film Transistor Employing Vapor Deposited Polyimide as A Gate Dielectric
Authors: Han Chang-Wook , Park Sang-Geun , Kim Chang-Yeon , Han Min-Koo , Hyung Gun-Woo , Lee Dong-Hyun , Pyo Sang-Woo , Kim Young Kwan
Published: April 2011

A top gate pentacene TFT employing vapor deposited polyimide as a gate dielectric was fabricated. Polyimide was co-evaporated from 6FDA and ODA monomers and annealed at 150 °C in vacuum. The degree of imidization was verified by FT-IR. A breakdown voltage of 0.9 MV/cm of polyimide film was measured by MIM structure. A top gate pentacene TFT with W/L=25 has 0.01 cm2/Vs as a mobility, about 103 as an on-off ratio (In/off), −7.5V as a threshold voltage and 9 V per decade as a sub-threshold slope.
A Novel Fabrication Technique for Developing Metal Nanodroplet Arrays
Authors: Edgar Christopher , Johns Chad , Islam M. Saif
Published: April 2011

Metal patterned lines on a substrate have been annealed and broken down into isolated linear arrays of alloyed metal nanoscale droplets. These droplets are selectively fabricated across large-scale areas by controlling the location metal is present on a substrate. The metal instability and formation into nanoscale particles forms similar to studies in Rayleigh Instability of metal at an elevated temperature. Experimental results discussed here show a change in droplet diameter and formation by controlling the metal width.
Functionalized Luminescent Oxide Nanoparticles as Biological Probes
Authors: Giaume Domitille , Casanova Didier , Lahlil Khalid , Sauviat Martin-Pierre , Alexandrou Antigoni , Gacoin Thierry , Boilot Jean-Pierre
Published: April 2011

Synthesis and functionalization of nanoparticles of yttrium vanadate doped with europium is described. Synthesis of yttrium vanadate leads to ovoid nanoparticles, with an average size of 24 nm. These nanoparticles are unstable in water, and surface charge can be brought by silicate, as proven by PCS, Zetametry and IR analyses. The nanoparticle surface is then functionalized with glycidoxypropyltrimethoxysilane. The rafting is characterized by 29Si MAS NMR, and ThermoGravimetric Analyses. This alkoxysilane presents an epoxy function which can then react with a nucleophilic molecule. The functionalization is studied by 29Si MAS NMR and TGA, whereas opening of the epoxy ring is studied by 13C MAS NMR. As an example of further reactivity, we chose to graft on the nanoparticles the active part of saxitoxin, a guanidinium group. This last functionalization is proven by optical experiments performed on a cell in biological conditions.
Microbial Synthesis of Noble Metal Nanoparticles using Metal-reducing Bacteria
Authors: Konishi Yasuhiro , Ohno Kaori , Saitoh Norizoh , Nomura Toshiyuki , Nagamine Shinsuke
Published: April 2011

Microbial synthesis of gold nanoparticles was achieved at 25°C and pH 7-1 using the mesophilic bacteriumShewanella algaewith H2as the electron donor. The microbial synthesis of gold nanoparticle was a fast process: 1 mM AuCl4−ions were completely reduced to insoluble gold within 30 min. At the solution pH 7, the gold nanoparticles of 10-20 nm were synthesized in the periplasmic space ofS. algaecells. When the solution pH was decreased to 1, the gold nanoparticles of 50-500 nm were precipitated extracellularly. The solution pH was an important factor in controlling the morphology of biogenic gold particles and location of gold deposition.
Study of PV Module Methylmetacrylate Encapsulation
Authors: Karabanov Sergey , Kukhmistrov Yuri
Published: April 2011

The paper deals with the study of PV module encapsulation using liquid methylmetacrylate composition hardened by UV radiation. The solar cells encapsulation method by methylmetacrylate composition in the glass-glass and glass PET-foil constructions of PV modules is investigated. The UV hardening modes of methylmetacrylate composition are investigated and developed. The studied method allows to eliminate heating during encapsulation and reduce the PV module production cost. The new method makes it possible to encapsulate solar cells on any substrates, including easily melted polymeric ones, and also in the glass-glass construction.

The structure and technological modes of liquid methylmetacrylate composition hardening during encapsulation have been investigated and selected. PV modules investigation for the resistance to external actions according to IEC61215 standard procedure provided positive results
Superconducting characteristics of MgB2 wires obtained by Reactive Liquid Mg Infiltration
Authors: Giunchi Giovanni , Ripamonti Giovanni , Perini Elena , Cavallin Tommaso , Bassani Enrico , Gambardella Umberto , Yang Yifeng , Young Edward A. , Bianchetti Marco , Beduz Carlo
Published: April 2011

Superconducting MgB2 wires, of different diameter and length, have been produced by the reactive Liquid Mg Infiltration process, also implemented with the addition of extra Mg, to completely fill the internal hole created from the normal infiltration process. The actual wires have an Iron external lining and the metallic Mg internally added has a twofold effect: to avoid Mg deficiency during the reaction and to increase the quenching resistance of the wire. The superconducting characteristics of the wires have been measured either at the liquid He and at the liquid Ne temperatures, on small samples cut from meter long wires. The typical critical current density in self field, at 27.1 K, is about 1000 A/mm2, a value of interest for many power applications. The extension of the manufacturing process to longer wire will be discussed as well as the effect of the metallic lining of the wires on the contact resistance and on the current injection length.
Synthesis and Responsive Properties of Dibenzoylmethane Metallobiomaterials
Authors: Fraser Cassandra L. , Chen Jianbin , Pfister Anne , Zhang Guoqing , Chen Yin Jie
Published: April 2011

Incorporation of ligands and metals into polymers by controlled methods yields multifunctional responsive materials. Dibenzoylmethane (dbm) is a beta-diketone ligand that binds metal and metalloid ions such as boron, iron or europium in a bidentate fashion producing complexes with one or more dbm chelates. Modification of dbm with biocompatible poly(lactic acid) (PLA) allows materials processing and leads to responsive metallobiomaterials. This is accomplished by modification of dbm with hydroxyl groups (e.g. dbmOH), that serve as initiators for lactide polymerization. Improved control is noted when dbm is protected as iron or boron complexes, namely Fe(dbmOH)3 or BF2(dbmOH). Furthermore, the iron center in iron tris(dbmOH) also functions as a catalyst for the polymerization; no tin catalyst is required. Redorange iron-centered three arm star polymers, Fe tris(dbmPLA), are obtained. Acid sensitivity of these materials provides a method for dbm ligand dissociation, demetalation and production of dbmPLA macroligands for coordination to other metals such as Eu. Currently, dbmPLA and its polymeric iron complexes are being fabricated as nanoparticles. Light emitting B and Eu dbm complexes are also under investigation. Progress in the synthesis, characterization and nanoscale fabrication of dbm ligand and metal based polymeric biomaterials is reported.
Angle Resolved Thermal Desorption Studies for Poly(methylvinylidene cyanide) and Poly(vinylidenefluoride trifluoroethylene)
Authors: Ilie Carolina C. , Jacobson P. A. , Poulsen Matt , Rosa Luis G. , Sahadeva-Reddy D. , Takacs James M. , Ducharme Stephen , Dowben P. A.
Published: April 2011

We compare water adsorption and desorption on ferroelectric copolymer poly(vinylidene fluoride-trifluoroethylene), and the dipole ordered polymer poly(methylvinylidene cyanide). The angle-resolved thermal desorption spectra prove that the absorbed water species interacts more strongly with poly(vinylidene fluoride-trifluoroethylene) than with poly(methylvinylidene cyanide). The angle resolved thermal desorption spectra shows large deviations from the cosine distribution for light illuminated poly(vinylidene fluoride-trifluoroethylene). Water desorption from poly(methylvinylidene cyanide) deviates from the cosine distribution without illumination.
Novel Silicon-Elastomers for Advanced Soft Lithography
Authors: Choi Kyung
Published: April 2011

High resolution pattern transfers in the nano-scale regime have been considerable challenges in ‘soft lithography’ to achieve nanodevices with enhanced performances. In this technology, the resolution of pattern integrations is significantly rely on the materials' properties of polydimethylsiloxane (PDMS) stamps. Since commercial PDMS stamps have shown limitations in nano-scale resolution soft lithography due to their low physical toughness and high thermal expansion coefficients, we developed stiffer, photocured PDMS silicon elastomers designed, specifically for nano-sized soft lithography and photopatternable nanofabrications.
Characterization of Electrospinning Fiber Diameter Distributions and Process Dynamics for Development of Real-Time Control
Authors: Yan Xuri , Gevelber Michael , Yu Jian , Rutledge Gregory
Published: April 2011

An integrated data acquisition/actuator control system is developed to conduct experiments investigating the fundamental dynamics for different operating conditions in an electrospinning system. The relation between measured variables (fiber current, whipping angle, jet length, and expulsion cone volume) to the resulting fiber diameter distribution is analyzed.
Fabrication of Energy Storage Media BST/PVDF-PAn
Authors: Luo Dabing , Guo Yan , Hao Hua , Liu Hanxing , Ouyang Shixi
Published: April 2011

Permittivity and anti-voltage ability commonly determined the energy storage density of material. Although composite could be molded easier than ceramic, its lower energy storage density prevented the material from application since the polymer usually took on poor dielectric constant. In order to enhance the energy storage performance of composite, PAn was introduced to PVDF by emulsion polymerization. SEM of the co-polymers showed that they could construct continuous media till the concentrate of aniline reached 25% while polymerizing. The permittivity of polymer rose along with the concentrate increasing of aniline and pH falling value of retreating solution. The permittivity and anti-voltage strength of composite also charged correspondingly. As a consequence, the energy storage density innovated much higher than ever. The maximum energy storage density could approach 0.9185Johr/cc.
Nano-Structural Control of Molecular-Pore Stacked (MPS) SiOCH Films Using Plasma Copolymerization Reaction
Authors: Yamamoto Hironori , Ito Fuminori , Tada Munehiro , Takeuchi Tsuneo , Furutake Naoya , Hayashi Yoshihiro
Published: April 2011

A novel plasma co-polymerization technology, using flexibly-mixed molecular gas of 6-membered ring-type vinyl-siloxane and 8-member ring-type one, has been developed for new interlayer dielectric film.
DNA Hybridization Detection using Fluorescent Zinc Selenide Quantum Dots
Authors: Wang Jun , Lei Pedro , Andreadis Stelios , Heckler Tracy , Mei Bing , Qiu Qi , Mountziaris T J
Published: April 2011

This work focuses on the development of biological analysis tools using zinc selenide quantum dots (ZnSe QDs). Conjugating water-dispersible ZnSe QDs with oligonucleotides of increasing length was found to increase their photoluminescence (PL) intensity monotonically up to a certain length. Varying the sequence of the oligonucleotide without changing its length does not produce any measurable PL intensity change. The stability of QDs in water was significantly enhanced after conjugation with oligonucleotides. DNA hybridization was studied using QDs functionalized with complementary oligonucleotides. Hybridization of complementary QD-oligonucleotide complexes causes significant PL intensity amplification and a measurable red shift of the PL emission peak. The QD-oligo complexes are very stable in water under ambient dark conditions. Finally, a size-dependent optimal dilution of free QDs was discovered, corresponding to an optimal inter-QD-spacing that results in the highest PL emission intensity from as-prepared QD dispersions. Ongoing experiments in our laboratory aim to develop multiplexed DNA probes and immunoassays by employing luminescent QDs emitting at different wavelengths.
Microfabricated, Wireless, Magnetoelastic Micro-Particles for the Detection of Bacillus Anthracis Spores
Authors: Wan Jiehui , Johnson Michael L. , Shu Huihua , Petrenko Valery A. , Chin Bryan A.
Published: April 2011

Magnetoelastic resonance biosensors were fabricated by immobilizing a bio-molecular recognition element onto the surface of Fe79B21 magnetoelastic particles (MEP). These sensors can be measured wirelessly and remotely for both in-air and in-liquid bacteria detection. Filamentous bacterio-phage that was selected specifically for the detection of Bacillus anthracis spores was employed as the biomolecular recognition element and immobilized onto the MEPs' surfaces. Attachment of the spores to the sensor surface due to specific phage-spore binding results in a shift in the resonance frequency of the biosensor. Insitu measurement of the resonance frequency of biosensors of 5×100×500 microns were used to determine the sensor response as a function of spore concentrations of 103 to 108 cfu/ml. Specificity of the sensor was evaluated by conducting tests using a mixture of Bacillus anthracis Sterne strain, Bacillus cereus and Bacillus megaterium spores.
Connected Electrodes by the Growth of Germanium Dioxide Nanowires
Authors: Wu Chun-I , Hogan Tim P.
Published: April 2011

Germanium dioxide nanowires have gained significant interest lately due to the the bandgap of 2.44 eV, and high index of refraction, n=1.63. In this paper we aim at investigating the lateral growth of high density metal-catalyzed germanium dioxide nanowires between electrodes. The gaps between two electrodes varied. The catalyst metal was placed on the electrodes, followed by a thermal annealing process, resulting in lateral growth of germanium dioxide whiskers with several microns length and eventually the formation of bridge-like nanostructures. These whiskers have certain unique properties, such as a high surface-to-volume ratio and the capability of connecting two electrodes. Because of these properties, the growth of whiskers from the electrodes has the potential to be developed as electronic devices such as nanosensors. These products are characterized by scanning electron microscopy (SEM), as well as X-Ray diffraction (XRD).
Protein Assembly Through Site-specific Interactions with Gold Nanoparticles
Authors: Hu Minghui , Qian Luping , Briñas Raymond P , Lymar Elena S , Hainfeld James F
Published: April 2011

A universal method is described to design and construct protein-nanoparticle assemblies controlled by nanoparticle functionality, and placement of genetic tag into proteins. Well-defined binding complexes of nanoparticles and two proteins, the adenovirus serotype 12 knob and the mycobacterium tuberculosis 20S proteasome, were formed through site-specific binding between 6x-histidine tags in proteins and nickel-nitrilotriacetic acid functional groups on gold nanoparticles.
Surface Stress Generation During Formation of Alkanethiol Self-assembled Monolayer (SAM)
Authors: Kanaga Subramanian Kanaga Karuppiah , Zhang Ruqin , Shrotriya Pranav , Chandra Abhijit , Sundararajan Sriram
Published: April 2011

Micro-machined cantilevers coated with self-assembled monolayers (SAM) of alkanethiols are being utilized as sensing elements for new generation of high-sensitivity chemical and biological sensors. Presence of chemical species is detected by resolving the surface stress change associated with absorption/adsorption of analyte molecules on the sensitized cantilever. Challenges to widespread use of micromechanical cantilever sensors are: susceptibility to vibrations, integration in a single device and understanding the mechanism governing surface stress generation. In the current work, surface stress development associated with formation of self-assembled-monolayers of alkanethiols was characterized using curvature interferometry. In order to understand the molecular mechanism underlying the surface stress generation, a multi-scale model is developed to predict the surface stress generated during absorption of the alkanethiols on a gold film.
Use of Anodized Titanium in Drug Delivery Applications
Authors: Yao Chang , Balasundaram Ganesan , Webster Thomas
Published: April 2011

One approach to improve the performance of current titanium implants is to create nanostructures via surface modification. Anodization is known to produce nanotubular structures on titanium surfaces when using fluorine containing solutions. Previous studies revealed enhanced osteoblast (bone-forming cell) adhesion and calcium deposition on anodized titanium possessing nanotubular structures compared to unanodized titanium. Moreover, it was found that protein adsorption (specifically, vitronectin and fibronectin) prior to cell adhesion increased on anodized compared to unanodized samples. These results all indicate that anodized titanium would be a good candidate for novel orthopedic implants. The nanotubes created by anodization have an inner diameter from 40 to 100 nm and a depth of a few hundred nanometers. In the present study, the drug delivery capability of such nanotubular structures was further characterized. Three different model drugs were tested: immunoglobulin G for foreign body response, bone morphogenetic protein active fragment for new bone growth, and penicillin/streptomycin for antimicrobial. First, these proteins were allowed to adsorb onto substrates for 24 h under room temperature. Then, the substrates with absorbed proteins were rinsed and transferred to new buffer solution kept at 37 °C. Buffer solution was collected and changed everyday. Finally, protein release from each substrate was measured using a commercial BCA assay kit. Results showed decreased immunoglobulin G adsorption, increased bone morphogenetic protein and penicillin/streptomycin adsorption on anodized titanium compared to unanodized ones. The release behavior of each protein on anodized and unanodized titanium is also studied.