bluuebunny/crossref_metadata_2025 huggingface dataset:
Spawning Migration of Adult Chinook Salmon (Oncorhynchus tshawytscha) Carrying External and Internal Radio Transmitters
Authors: Gray Robert H. , Haynes James M.
Published: April 2011

Upstream movements of radio-tagged and control adult chinook salmon (Oncorhynchus tshawytscha) were monitored during spring and fall 1976 and spring 1977 in the lower Snake River, southeastern Washington. Travel time from point of fish release and percent return to upstream trapping facilities were compared for experimental and control fish. Experimental fish carried anchor tags, and either external or internal radio transmitters. Control fish carried anchor tags only. Chinook salmon that lost external transmitters moved upriver more slowly than control fish although percent returns to upriver trapping facilities were similar. Travel times and percent returns of chinook salmon that retained external transmitters did not differ significantly from those of control fish. Although some salmon tagged with internal transmitters moved upriver, all failed to cross Little Goose Dam 6.5 km from the release site. Most internally tagged salmon eventually swam downstream. Key words: chinook salmon, biotelemetry, behavior, migration, radiotelemetry, bioengineering
Artificial Transmission to and Susceptibility of Puget Sound Fish to Viral Erythrocytic Necrosis (VEN)
Authors: MacMillan John R. , Mulcahy Dan
Published: April 2011

In Puget Sound, Wash., the incidence of viral erythrocytic necrosis (VEN) varied geographically from 0 to 17% in chum salmon (Oncorhynchus keta) and from 4 to 59% in Pacific herring (Clupea harengus pallasi). The disease was experimentally transmitted by intraperitoneal injection to chum, pink (O. gorbuscha), coho (O. kisutch), chinook (O. tshawytscha), sockeye (O. nerka), and Atlantic (Salmo salar) salmon, and rainbow (S. gairdneri), brown (S. trutta), and brook (Salvelinus fontinalis) trout. The disease was transmitted to chum salmon and brook trout by waterborne virus. Virus obtained from herring was experimentally transmitted into chum salmon by intraperitoneal injection. Key words: viral erythrocytic necrosis, fish disease, transmission
Interactions of Chlorine, Temperature Change (ΔT), and Exposure Time on Survival of Striped Bass (Morone saxatilis) Eggs and Prolarvae
Authors: Burton Dennis T. , Hall Jr. Lenwood W. , Margrey Stuart L. , Small Robert D.
Published: April 2011

Effects of total residual chlorine (TRC), change in temperature (ΔT), and exposure time were established for eggs and prolarvae of striped bass, Morone saxatilis, under test conditions designed to simulate entrainment by power plants. Prolarvae were found to be more sensitive than eggs under the same test conditions. In contrast to the predominant effect of TRC and exposure time on eggs, TRC and ΔT and exposure time were all found to be important in causing mortality of prolarvae. The study shows that in an evaluation of the potential effects of chlorinated power plant cooling waters to striped bass ichthyoplankton, a systematic study must be made of the interactions of TRC, ΔT, and exposure time. Key words: chlorine, total residual chlorine, temperature change, ΔT, exposure time, Morone saxatilis, fish eggs, fish larvae, predictive mortality model
Molt-Related Sensitivity of Daphnia pulex in Toxicity Testing
Authors: Lee David Robert , Buikema Jr. Arthur L.
Published: April 2011

Continuous and short-term exposures of Daphnia pulex to 0.56 mg Cr/L showed that these animals undergo cyclic changes in susceptibility. Short-term exposure (2 h) followed by transfer to clean water for 22 h resulted in significantly higher mortality for individuals that molted during exposure. Continuous exposure to chromate resulted in significantly shorter mean survival times for animals that had molted < 4 h before being placed in chromate solution. Because laboratory cultures can be synchronized with respect to molting, the effects of cyclic sensitivity can bias bioassay results. By examining the animals at the beginning of the test, the degree of synchrony can be determined and appropriate steps taken. Key words: bioassay, Daphnia pulex, chromium toxicity, molting
Chloride Inhibition of Nitrite-Induced Methemoglobinemia in Channel Catfish (Ictalurus punctatus)
Authors: Tomasso J. R. , Simco Bill A. , Davis Kenneth B.
Published: April 2011

Exposure of channel catfish (Ictalurus punctatus) fingerlings for 24 h to 1.0, 2.5, and 5.0 mg/L nitrite (pH = 7; hardness = 40 mg/L; temperature = 22–25 °C) produced methemoglobin levels of 20.7 ± 1.9%, 59.8 ± 1.9%, and 77.4 ± 1.4% (SE), respectively. However, methemoglobin levels were not elevated when fish were simultaneously exposed to 1.0, 2.5, and 5.0 mg/L nitrite and 25, 50, and 100 mg/L sodium chloride, respectively. Acclimation to sodium chloride for 24 h before exposure to nitrite did not enhance the inhibitory action of sodium chloride. Fish exposed to 5 mg/L nitrite for 5 h developed 42.5 ± 3.8% methemoglobin. When transferred to water containing 5 mg/L nitrite and 250 mg/L sodium chloride, methemoglobin levels returned to normal within 24 h. Environmental chloride probably inhibits methemoglobin formation by competing with nitrite for entrance into the gills of the fish. An ionic ratio of 16 Cl− to 1 NO2− is capable of complete suppression of nitrite-induced methemoglobin formation. Bicarbonate ion present in the test water (1 meq/L) may also have contributed to the inhibitive action of chloride. Key words: nitrite, methemoglobin, chloride, channel catfish
APPLICATIONS OF MAGNETIC ΨDO TECHNIQUES TO SAPT
Authors: DE NITTIS GIUSEPPE , LEIN MAX
Published: April 2011

In this review, we show how advances in the theory of magnetic pseudodifferential operators (magnetic ΨDO) can be put to good use in space-adiabatic perturbation theory (SAPT). As a particular example, we extend results of [24] to a more general class of magnetic fields: we consider a single particle moving in a periodic potential which is subjected to a weak and slowly-varying electromagnetic field. In addition to the semiclassical parameter ε ≪ 1 which quantifies the separation of spatial scales, we explore the influence of an additional parameter λ that allows us to selectively switch off the magnetic field.

We find that even in the case of magnetic fields with components in [Formula: see text], e.g., for constant magnetic fields, the results of Panati, Spohn and Teufel hold, i.e to each isolated family of Bloch bands, there exists an associated almost invariant subspace of L2(ℝd) and an effective hamiltonian which generates the dynamics within this almost invariant subspace. In case of an isolated non-degenerate Bloch band, the full quantum dynamics can be approximated by the hamiltonian flow associated to the semiclassical equations of motion found in [24].
THE ADHM CONSTRUCTION OF INSTANTONS ON NONCOMMUTATIVE SPACES
Authors: BRAIN SIMON , VAN SUIJLEKOM WALTER D.
Published: April 2011

We present an account of the ADHM construction of instantons on Euclidean space-time ℝ4from the point of view of noncommutative geometry. We recall the main ingredients of the classical construction in a coordinate algebra format, which we then deform using a cocycle twisting procedure to obtain a method for constructing families of instantons on noncommutative space-time, parametrized by solutions to an appropriate set of ADHM equations. We illustrate the noncommutative construction in two special cases: the Moyal–Groenewold plane [Formula: see text] and the Connes–Landi plane [Formula: see text].
BROADBAND TERAHERTZ WAVE GENERATION, DETECTION AND COHERENT CONTROL USING TERAHERTZ GAS PHOTONICS
Authors: LIU JINGLE , DAI JIANMING , LU XIAOFEI , HO I-CHEN , ZHANG X.-C.
Published: April 2011

Terahertz (THz) gas photonics uses gas as THz emitter and sensor for time-domain spectroscopy. Unique properties of the gas promise scalable, strong THz wave generation with broad spectral range covering the entire THz gas (0.3 THz to 35 THz). The systematic study of THz wave generation and detection in different gases shows that the generation efficiency is monotonically decreasing with the ionization potential of the gas molecules while the detection efficiency is linearly proportional to the third order nonlinear coefficient of the gas molecules. We also discuss the development of THz wave detection using laser-induced fluorescence and coherent control with THz gas photonics.
HOW DO WE LOSE EXCITATION IN THE GREEN?
Authors: WETZEL CHRISTIAN , XIA YONG , ZHAO WEI , LI YUFENG , ZHU MINGWEI , YOU SHI , ZHAO LIANG , HOU WENTING , STARK CHRISTOPH , DIBICCARI MICHAEL , LIU KAI , SHUR MICHAEL S. , GARRETT GREGORY A. , WRABACK MICHAEL , DETCHPROHM THEERADETCH
Published: April 2011

Efficiency droop and green gap are terms that summarize performance limitations in GaInN / GaN high brightness light emitting diodes (LEDs). Here we summarize progress in the development of green LEDs and report on time resolved luminescence data of polar c -plane and non-polar m -plane material. We find that by rigorous reduction of structural defects in homoepitaxy on bulk GaN and V -defect suppression, higher efficiency at longer wavelengths becomes possible. We observe that the presence of donor acceptor pair recombination within the active region correlates with lower device performance. To evaluate the aspects of piezoelectric polarization we compare LED structures grown along polar and non-polar crystallographic axes. In contrast to the polar material we find single exponential luminescence decay and emission wavelengths that remain stable irrespective of the excitation density. Those findings render high prospects for overcoming green gap and droop in non-polar homoepitaxial growth.
SILICON FINFETS AS DETECTORS OF TERAHERTZ AND SUB-TERAHERTZ RADIATION
Authors: STILLMAN W. , DONAIS C. , RUMYANTSEV S. , SHUR M. , VEKSLER D. , HOBBS C. , SMITH C. , BERSUKER G. , TAYLOR W. , JAMMY R.
Published: April 2011

We report on terahertz detection (from 0.2 THz to 2.4 THz) by Si FinFETs of different widths (with 2, 20, and 200 fins connected in parallel). FinFETs (with a small number of fins and with feature sizes as short as 20 nm to 40 nm) showed a very high responsivity (far above that previously measured for standard CMOS). We explain this improvement by negligible narrow channel effects.
PROGRESS IN DEVELOPMENT OF ROOM TEMPERATURE CW GASB BASED DIODE LASERS FOR 2-3.5 μM SPECTRAL REGION
Authors: HOSODA TAKASHI , CHEN JIANFENG , TSVID GENE , WESTERFELD DAVID , LIANG RUI , KIPSHIDZE GELA , SHTERENGAS LEON , BELENKY GREGORY
Published: April 2011

Recent progress and state of GaSb based type-I lasers emitting in spectral range from 2 to 3.5 μm is reviewed. For lasers emitting near 2 μm an optimization of waveguide core width and asymmetry allowed reduction of far field divergence angle down to 40-50 degrees which is important for improving coupling efficiency to optical fiber. As emission wavelength increases laser characteristics degrade due to insufficient hole confinement, increased Auger recombination and deteriorated transport through the waveguide layer. While Auger recombination is thought to be an ultimate limiting factor to the performance of these narrow bandgap interband lasers we demonstrate that continuous improvements in laser characteristics are still possible by increasing hole confinement and optimizing transport properties of the waveguide layer. We achieved 190, 170 and 50 mW of maximum CW power at 3.1, 3.2 and 3.32 μm wavelengths respectively. These are the highest CW powers reported to date in this spectral range and constitute 2.5-fold improvement compared to previously reported devices.
CONNECTING ELECTRICAL AND STRUCTURAL DIELECTRIC CHARACTERISTICS
Authors: BERSUKER G. , VEKSLER D. , YOUNG C. D. , PARK H. , TAYLOR W. , KIRSCH P. , JAMMY R. , MORASSI L. , PADOVANI A. , LARCHER L.
Published: April 2011

An attempt is made to correlate electrical measurement results to specific defects in the dielectric stacks of high-k/metal gate devices. Defect characteristics extracted from electrical data were compared to those obtained by ab initio calculations of the dielectric structures. It is demonstrated that oxygen vacancies in a variety of charge states and configurations in the interfacial SiO2layer of the high-k gate stacks contribute to random telegraph noise signal, time-dependent dielectric breakdown, and the flatband voltage roll-off phenomenon.
ADVANCED SOLUTIONS FOR MOBILITY ENHANCEMENT IN SOI MOSFETS
Authors: PHAM-NGUYEN L. , FENOUILLET-BERANGER C. , PERREAU P. , DENORME S. , GHIBAUDO G. , FAYNOT O. , SKOTNICKI T. , OHATA A. , CASSE M. , IONICA I. , VAN DEN DAELE W. , PARK K-H. , CHANG S-J. , BAE Y-H. , BAWEDIN M. , CRISTOLOVEANU S.
Published: April 2011

SOI technology offers ample room for scaling, performance improvement, and innovations. The current status is reviewed by focusing on several technological options for boosting the transport properties in SOI MOSFETs. The impact of series resistance, high-K dielectrics, and metal gate in advanced transistors is discussed. Carrier mobility measurements as a function of channel length and temperature reveal the beneficial effect of strain, mitigated however by various types of defects. The experimental data is exclusively collected from state-of-the-art, ultrathin body, fully depleted MOSFETs. Simple models are presented to clarify the mobility behavior.
ELECTRON SCATTERING IN BURIED InGaAs/HIGH-K MOS CHANNELS
Authors: OKTYABRSKY S. , NAGAIAH P. , TOKRANOV V. , YAKIMOV M. , KAMBHAMPATI R. , KOVESHNIKOV S. , VEKSLER D. , GOEL N. , BERSUKER G.
Published: April 2011

Hall electron mobility in buried QW InGaAs channels, grown on InP substrates with HfO 2 gate oxide, is analyzed experimentally and theoretically as a function of top barrier thickness and composition, carrier density, and temperature. Temperature slope α in μ ~Tα dependence is changing from α=-1.1 to +1 with the reduction of the top barrier thickness indicating the dominant role of remote Coulomb scattering (RCS) in interface-related contribution to mobility degradation. Insertion of low-k SiO x interface layer formed by oxidation of thin in-situ MBE grown amorphous Si passivation layer has been found to improve the channel mobility, but at the expense of increased EOT. This mobility improvement is also consistent with dominant role of RCS. We were able to a obtain a reasonable match between experiment and simple theory of the RCS assuming the density of charges at the high-k/barrier interface to be in the range of (2-4)×1013 cm-2.
LOW-POWER BIOMEDICAL SIGNAL MONITORING SYSTEM FOR IMPLANTABLE SENSOR APPLICATIONS
Authors: HAIDER MOHAMMAD RAFIQUL , HOLLEMAN JEREMY , MOSTAFA SALWA , ISLAM SYED KAMRUL
Published: April 2011

Implantable biomedical sensors and continuous real time in vivo monitoring of various physiological parameters requires low-power sensor electronics and wireless telemetry for transmission of sensor data. In this article, generic blocks required for such systems have been demonstrated with design examples. Ideally neural or electro-chemical sensor signal monitoring units comprise of low noise amplifiers, current or voltage mode analog to digital domain data conversion circuits and wireless telemetry circuits. The low-noise amplifier described here has a novel open loop amplifier scheme used for neural signal recording systems. The design has been implemented using 0.5-μm SOI-BiCMOS process. The fabricated chip can work with 1 V supply and consumes 805 nA. The current mode analog to digital conversion signal processing circuitry takes the current signal as an input and generates a pulse-width modulated data signal. The data signal is then modulated with a high frequency carrier signal to generate FSK data for wireless transmission. The design is fabricated in 0.5-μm standard CMOS process and consumes 1.1 mW of power with 3.5 V supply.
LOW-FREQUENCY ELECTRONIC NOISE IN GRAPHENE TRANSISTORS: COMPARISON WITH CARBON NANOTUBES
Authors: LIU GUANXIONG , STILLMAN WILLIAM , RUMYANTSEV SERGEY , SHUR MICHAEL , BALANDIN ALEXANDER A.
Published: April 2011

We report results of the experimental investigation of the low-frequency noise in graphene transistors. The graphene devices were measured in three-terminal configuration. The measurements revealed low flicker noise levels with the normalized noise spectral density close to 1/f (f is the frequency) and the Hooge parameter αH ~10-3. Both top-gate and back-gate devices were studied. The analysis of the noise spectral-density dependence on the gate biases helped us to elucidate the noise sources in these devices. We compared the noise performance of graphene devices with that of carbon nanotube devices. It was determined that graphene devices works better than carbon nanotube devices in terms of the low-frequency noise. The obtained results are important for graphene electronic, communication and sensor applications.
ZnO NANOCRYSTALLINE HIGH PERFORMANCE THIN FILM TRANSISTORS
Authors: BAYRAKTAROGLU BURHAN , LEEDY KEVIN , NEIDHARD ROBERT
Published: April 2011

In this study, nc - ZnO films deposited in a Pulsed Laser Deposition (PLD) system at various temperatures were used to fabricate high performance transistors. As determined by Transmission Electron Microscope (TEM) images, nc - ZnO films deposited at a temperature range of 25°C to 400°C were made of closely packed nanocolums showing strong orientation. The influences of film growth temperature and post growth annealing on device performance were investigated. Various gate dielectric materials, including SiO 2, Al 2 O 3, and HfO 2 were shown to be suitable for high performance device applications. Bottom-gate FETs fabricated on high resistivity (>2000 ohm-cm) Si substrates demonstrated record DC and high speed performance of any thin film transistors. Drain current on/off ratios better than 1012 and sub-threshold voltage swing values of less than 100mV/decade could be obtained. Devices with 2μm gate lengths produced exceptionally high current densities of >750mA/mm. Shorter gate length devices (LG=1.2μm) had current and power gain cut-off frequencies, f T and f max , of 2.9GHz and 10GHz, respectively.
ZINC OXIDE NANOPARTICLES FOR ULTRAVIOLET PHOTODETECTION
Authors: SAWYER SHAYLA , QIN LIQIAO , SHING CHRISTOPHER
Published: April 2011

Zinc Oxide ( ZnO ) nanoparticles were created by a top-down wet-chemistry synthesis process ( ZnO - A ) and then coated with polyvinyl-alcohol (PVA) ( ZnO - U ). In ZnO - U , strong UV emission was apparent while the parasitic green emission, which normally appears in ZnO suspensions, was suppressed. A standard lift-off process via e-beam lithography was used to fabricate a detector by evaporating Aluminum ( Al ) as ohmic electrodes on the ZnO nanoparticle film. Photoconductivity experiments showed that linear current-voltage response were achieved and the ZnO - U nanoparticles based detector had a ratio of UV photo-generated current more than 5 times better than that of the ZnO - A based detector. In addition, non-linear current-voltage responses were observed when interdigitated finger Gold ( Au ) contacts were deposited on ZnO - U . The UV generated current to dark current ratios were between 4 and 7 orders of magnitude, showing better performance than the photodetector with Al contacts. ZnO - U were also deposited on Gallium Nitride ( GaN ) and Aluminum Gallium Nitride ( AlGaN ) substrates to create spectrally selective photodetectors. The responsivity of detector based on AlGaN is twice that of commercial UV enhanced Silicon photodiodes. These results confirmed that ZnO nanoparticles coating with PVA is a good material for small-signal, visible blind, and wavelength selective UV detection.
CARBON-BASED NANOELECTROMECHANICAL DEVICES
Authors: BENGTSSON STEFAN , ENOKSSON PETER , GHAVANINI FARZAN A. , ENGSTRÖM KLAS , LUNDGREN PER , CAMPBELL ELEANOR E. B. , EK-WEIS JOHAN , OLOFSSON NIKLAS , ERIKSSON ANDERS
Published: April 2011

Carbon-based nanoelectromechanical devices are approaching applications in electronics. Switches based on individual carbon nanotubes deliver record low off-state leakage currents. Arrays of vertically aligned carbon nanotubes or nanofibers can be fabricated to constitute varactors. Very porous, low density arrays of quasi-vertically aligned arrays of carbon nanotubes behave mechanically as a single unit with very unusual material properties.
CHARGE PUDDLES AND EDGE EFFECT IN A GRAPHENE DEVICE AS STUDIED BY A SCANNING GATE MICROSCOPE
Authors: CHAE J. , YANG H. J. , BAEK H. , HA J. , KUK Y. , JUNG S. Y. , SONG Y. J. , ZHITENEV N. B. , STROSCIO J. A. , WOO S. J. , SON Y.-W.
Published: April 2011

Despite the recent progress in understanding the geometric structures of defects and edges in a graphene device (GD), how such defects and edges affect the transport properties of the device have not been clearly defined. In this study, the surface geometric structure of a GD was observed with an atomic force microscope (AFM) and the spatial variation of the transport current by the gating tip was measured with scanning gate microscopy (SGM). It was found that geometric corrugations, defects and edges directly influence the transport current. This observation is linked directly with a proposed scattering model based on macroscopic transport measurements.
A TWO-STAGE EVOLUTIONARY APPROACH FOR EFFECTIVE CLASSIFICATION OF HYPERSENSITIVE DNA SEQUENCES
Authors: KAMATH UDAY , SHEHU AMARDA , DE JONG KENNETH A.
Published: April 2011

Hypersensitive (HS) sites in genomic sequences are reliable markers of DNA regulatory regions that control gene expression. Annotation of regulatory regions is important in understanding phenotypical differences among cells and diseases linked to pathologies in protein expression. Several computational techniques are devoted to mapping out regulatory regions in DNA by initially identifying HS sequences. Statistical learning techniques like Support Vector Machines (SVM), for instance, are employed to classify DNA sequences as HS or non-HS. This paper proposes a method to automate the basic steps in designing an SVM that improves the accuracy of such classification. The method proceeds in two stages and makes use of evolutionary algorithms. An evolutionary algorithm first designs optimal sequence motifs to associate explicit discriminating feature vectors with input DNA sequences. A second evolutionary algorithm then designs SVM kernel functions and parameters that optimally separate the HS and non-HS classes. Results show that this two-stage method significantly improves SVM classification accuracy. The method promises to be generally useful in automating the analysis of biological sequences, and we post its source code on our website.
Future Directions for Through Silicon Vias
Authors: Fischer Paul B. , Morrow Patrick , Baskaran Rajashree , O'Brien Kevin
Published: April 2011

Die stacking using Through Silicon Vias (TSVs) is a promising path for short, dense, and low capacitance interconnects. Logic to memory and logic to logic stacking are specific examples of applications which directly benefit from TSV technology. Low capacitance TSVs offer power efficient path to reach > 1TB/s bandwidths. In the case of logic-to-logic stacking power can be reduced by up to 50% for a deeply pipelined machine (1). Despite clear technical advantages prolific adoption of TSV technologies has been limited in part by implementation costs. Materials and equipment improvements are improving the probability of finding TSV based stacking applications which justify the cost. Continued scaling will further reduce costs and create ongoing material and equipment opportunities and opportunities for new TSV applications. After reviewing specific logic to memory and logic to logic applications, future scaling directions will be discussed.
Conformal Electroless Deposition of Barrier and Cu Seed Layers for Realizing All-Wet TSV Filling Process
Authors: Shingubara Shoso , Inoue Fumihiro , Yokoyama Takumi , Miyake Hiroshi , Shimizu Tomohiro , Terui Toshifumi , Tanaka Shukichi , Kondo Kazuo
Published: April 2011

Conformal electroless deposition of barrier and seed layers was studied for fabrication of a high aspect ratio through-Si via (TSV). Formation of a thin barrier metal layer of Ni-B and Co-B is possible using a Au nanoparticle (Au-NP) catalyst, which is densely adsorbed on the SiO2 of the TSV sidewall. A silane coupling agent of 3-aminopropyl-triethoxysilane is effective for enhancement of the adsorption density of Au-NP. A conformal electroless Cu layer is deposited on the barrier layer by displacement plating without a catalyst. These results strongly suggest that an all-wet process for the formation of Cu-filled TSV with a high aspect ratio is possible.
Role of Additives in the Electrodeposition of Sn, Ag and Sn-Ag Films from Iodide-Pyrophosphate Solution
Authors: Venkatasamy Venkatram , Riemer Steven , Tabakovic Ibro , Kief Mark
Published: April 2011

Studies towards the understanding of the electrodeposition Sn-Ag alloys from KI-K4P2O7 solution and the effect of PEG 600 and Hydrazine Hydrochloride additives on their electrochemistry and material properties is presented. PEG acts as a complexing agent that reduces the difference in the reduction potentials of Sn+2 and Ag+ species. Hydrazine Hydrochloride acts as an anti-oxidant of Sn+2 species and also a reducing agent of Sn+4 species to Sn+2. Hydrazine Hydrochloride also prevents the formation of Sn dendrites during electrodeposition, as the presence of Sn+4 is being proposed as one of the main causes of the dendrite formation. The ideal deposition conditions included the bath composition of Ag at 0.0035 M and deposition current density of 40 mA/cm2. Stress measurements of the Sn-Ag films shows that it is Tensile. X-Ray analysis of the deposit showed the presence of pure Sn and Ag3Sn intermetallic in the deposit.
Investigation of Laterally-Enhanced Growth Mechanism of Au Electrodeposition onto SiO2 Surface Modified with Organic Molecules
Authors: Kobayashi Chiaki , Yoshida Shuhei , Saito Mikiko , Homma Takayuki
Published: April 2011

We investigated the influence of electrodeposition conditions to the laterally-enhanced growth from a patterned electrode onto a SiO2 surface modified with organic molecules. After modifying the SiO2 surface with polyamidoamine (PAMAM) or self-assembled monolayers (SAMs) of aminopropyl- triethoxysilane (APTES), electrodeposition was carried out toward lateral direction on the SiO2 surface. In order to investigate the influence of the coverage of the organic molecules, the different coverage of APTES-SAMs on the SiO2 were prepared, and it was suggested that Au ions adsorbed at APTES-SAMs enhance the lateral growth. It was also confirmed that condition of the laterally- enhanced growth, such as thickness and morphology, was changed in accordance with the change in the applied potential and the concentration of Au ions in the bath.
Platinum Islands on SAMs as Template for Enzyme-Catalyzed Glucose Oxidation
Authors: Lenz Jennifer , Gajdzik Janine , Natter Harald , Hempelmann Rolf , Kohring Gert-Wieland , Giffhorn Friedrich , Manolova Mila , Kolb Dieter M.
Published: April 2011

Multilayer electrodes for highly enantioselective sugar conversion are obtained by using monoatomically high platinum islands as pattern for further electrode modification with pyranose-2-oxidase (P2Ox). We describe this kind of electrode for the glucose oxidation. The reaction is monitored via the H2O2 production by the enzyme as side product. As first layer, a self-assembled monolayer (SAM) is arranged on the Au(111) surface via dip coating in a solution of 4-mercaptopyridine. On top of the SAM, a controlled distribution of platinum islands is obtained by a combination of electroless and electrochemical deposition using a solution of K2PtCl4. The platinum islands have a diameter of about 6 nm. Thereon, poly(allylamine hydrochloride) (PAA) obtained by dip coating provides a linker for immobilization of the enzyme pyranose-2-oxidase. Our assumption is that only one enzyme molecule is bound to one platinum island. This well ordered surface structure is probably the reason for the very high conversion efficiency.
Movement of Hydrogen during SCC of SUS310S Stainless Steel
Authors: Masuda Hiroyuki
Published: April 2011

We have found that less noble potential region existed near the crack tip on SUS304 and SUS316L stainless steel and around the crack on SUS310S stainless steel. Ag decoration was done at the same time to study the relation between the less noble potential region and hydrogen distribution. The results showed there is a good correlation between them. MFM and KFM observation at less noble potential region on SUS316L and SUS310S stainless steel revealed that hydrogen-induced martensite existed at less noble potential region. In present work, repeated crack growth tests were done to study the relation between the movement of hydrogen and the crack formation. The results show that small cracks are produced when hydrogen-induced martensite phase is formed ahead of the crack tip and join together with hydrogen-induced martensite phase becomes former austenite phase.
Combining Raman Microprobe and XPS to Study High-Temperature Oxidation of Metals
Authors: Windisch Charles F. , Henager Charles , Engelhard Mark , Bennett Wendy
Published: April 2011

Raman microprobe spectroscopy was applied in studies of high-temperature air oxidation of a ferritic alloy (HT-9) in the absence and presence of zirconia coatings with the objective of evaluating the technique as a way to quickly screen candidate cladding materials and actinide-based mixed oxide fuel mixtures for advanced nuclear reactors. When oxidation was relatively uniform, Raman spectra collected using microscope optics with low spatial resolution were found to be similar to those collected with conventional Raman spectroscopy. These spectra could be used to identify major oxide corrosion products and follow changes in the composition of the oxides due to heating. However, when the oxidation films were comprised of multiple layers of varying composition, or with layers containing metallic phases, techniques with higher depth resolution and sensitivity to zero-valence metals were necessary. The requirements were met by combining Raman microprobe using different optical configurations and x-ray photoelectron spectroscopy.
Dealloying Studies of Cu3Pd Single Crystal Surfaces
Authors: Meimandi Shilan , Renner Frank U.
Published: April 2011

Nano-porous metals formed by dealloying have application potential in a variety of fields such as catalysts, actuators, biomedical sensors and fuel cells. Several aspects of formation of porous surface during dealloying have not completely been understood. The Cu-Pd system is interesting as a model system for corrosion as well as a potential catalyst material. The initial dealloying and selective dissolution of single-crystals Cu3Pd (111) and Cu3Pd (100) in 0.1 M H2SO4 in the potential range of 400-800mV has been studied. With in-situ X-ray diffraction (Synchrotron Light), we observed the epitaxial Pd layer peak to appear by increasing the potential close to the critical potential. Ex-Situ atomic force microscopy (AFM) showed the formation of nanoscale islands of Pd (20-50 nm). Our aim in this project is to study the initial steps of dealloying of well-defined Cu-Pd surfaces on the atomic scale and to compare the results to the Cu-Au system.
Evaluation of the Local Chloride Concentration and the Local Mechanical Stresses in Intergranular Damages Grown on a 2024 Aluminum Alloy
Authors: Larignon Céline , Alexis Joël , Andrieu Eric , Baret-Blanc Christine , Odemer Grégory
Published: April 2011

The corrosion behavior of a 2024 T351 aluminum alloy exposed to a chloride solution was studied in the present paper. The work was focused on the effect of an environmental and thermal cyclic exposure to corrosive media and aimed to identify the main parameters explaining the changes observed between continuous and cyclic immersion tests. Optical and scanning electron microscope observations showed an increase of the intergranular corrosion damage with the extension of the corrosion from the grain boundaries to the subgrain boundaries for samples exposed to cyclic tests. An experimental set-up, including a laser beam, allowed mechanical stresses induced by the solidification of the electrolyte trapped in the corrosion damage during exposure to negative temperatures to be revealed and the chloride concentration of the electrolyte to be determined. Results were helpful in proposing corrosion mechanism during thermal and environmental cyclic exposure to chloride solutions.
Effect of Phase on the Electrochemical and Morphological Properties of Praseodymium-Based Coatings
Authors: Treu Becky L. , Fahrenholtz William , O'Keefe Matthew , Morris Eric , Albers Richard
Published: April 2011

The corrosion protection of epoxy-polyamide primers containing either hexagonal Pr2O3 or cubic Pr6O11 inhibitors deposited on chromate conversion coated Al 2024-T3 substrates was studied. Electrochemical evaluations, scanning electron microscopy with energy dispersive spectroscopy, and x-ray diffraction were used to characterize primers. The electrochemical response of coated panels prior to and following ASTM B117 salt spray exposure was also studied. The addition of PrOx species to the primer matrix improved the corrosion protection of artificial defects by decreasing icorr values from ~10-7 to ~10-9 A/cm2, increasing the passivation range (> 300 mV), and shifting Ecorr values to more negative potentials. After salt spray testing, Pr-hydroxide/hydroxycarbonate species were present on the surfaces of the primers. The addition of Pr2O3 afforded enhanced corrosion protection compared to the addition of Pr6O11 because Pr2O3 is a more reactive phase that provided more Pr3+ species for transport and reaction than Pr6O11.
Electrochemical effect of Gemini Surfactant and Co-Surfactants on Corrosion Inhibition of Steel in Acid Medium
Authors: Asefi Dourna , Arami Mokhtar , Mahmoodi Niyaz Mohammad
Published: April 2011

The effect of chain length compatibility on corrosion the inhibition effect of mixed inhibitor systems of cationic gemini surfactant, l,4-butan-bis (dodecyl dimethyl ammonium bromide) (designated as 12-4-12) with nonionic co-surfactants, C7OH (1-heptanol), C12OH (1-dodecanol) and C15OH (1-pentadecanol), on low carbon steel in acid medium was studied using weight loss, open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) measurements. The data demonstrated that the corrosion rate decreased by increasing surfactant concentration. In addition, less chain length difference causes more compatibility and inhibition on behavior of surfactant and co-surfactant mixture. Inhibition efficiency for C12OH + gemini surfactant was increased compared to the other mixtures explored.
Effect of pH on the Corrosion Behavior of Reinforcing Steel in Simulated Concrete Pore Solutions
Authors: Zhu Yan-Feng , Du Rong Gui , Xu Hui , Li Yan , Tang Fang-Miao , Chen Wen , Lin Chang-Jian
Published: April 2011

Reinforcing steel in concrete is usually in a passive state due to the high alkalinity of the concrete pore solution. However, the passivity may be lost and the corrosion occurs on the steel by a decrease of pH due to carbonation. In this work, the effect of pH on the corrosion behavior of reinforcing steel in simulated concrete pore solutions was studied by potentiodynamic anodic polarization, a scanning microreference electrode and scanning electron microscopy. The results showed that reinforcing steel exhibited different corrosion characteristics in the solutions with different pH values, the steel was in a state of passivity in the pure simulated pore solution, and the potential distribution on the reinforcing steel surface changed in homeostasis. When the pH value of the solution decreased to 11.30, localized corrosion occurred on the steel surface by the measurement of the steel potential distribution. This value is higher than that of the polarization curve measurements.
Corrosion Performance of Composite Galvanic Coatings with Variable Concentration of Polymeric Nanoaggregates and/or Cr(III) Conversion Layers
Authors: Koleva Dessi , Taheri P. , Tsvetkova Neli , Boshkov N. , Van Breugel Klaas , De Wit J. Hans W. , Mol J.M.C.
Published: April 2011

This paper reports on the corrosion performance of composite zinc layers (~ 8µm) on a steel substrate, considering the influence of nano-aggregates and Cr(III) conversion layers, compared to control (only Zn layers) conditions. The main factors, influencing the corrosion performance of Zn in this study are: a) the effect of two concentrations of polymeric nano-aggregates (0.1g/l and 0.3g/l PEO113-b-PS218 core-shell micelles in the starting electrolyte); b) the effect of Cr(III) conversion layers on both pure Zn and composite Zn layers. For most of the hereby investigated time intervals i.e. treatment in aerated 5% NaCl from 2h until 120h, the composite coatings present higher corrosion resistance, especially within longer treatment. Corrosion current densities are similar to Zn, however, anodic currents are significantly lower. After treatment in NaCl, the composite Zn coatings present a more homogenous product layer, formed as a result of the presence of the nano-aggregates. The additional Cr(III) treatment does not significantly improve the corrosion resistance of the composite coatings for the hereby investigated time intervals.
Nanowire-Nanoparticle Conjugate Photolytic Devices
Authors: Kalkan A. Kaan , MacLaskey Sean , Jones Ryan , Topal Cagri O.
Published: April 2011

The present work demonstrates hydrogen generation by nanowire-nanoparticle conjugate structures under visible radiation. The mechanism of hydrogen generation is attributed to photolytic cleavage of water. The nanostructures are synthesized by sol-gel and reduction chemistries and characterized by XRD, SEM, TEM, and optical spectroscopy. Photolysis is analyzed by gas chromatography. We discuss the possible mechanisms involved in the observed photolysis in terms of unique attributes of the multifunctional nanostructures, such as efficient channeling of photocarriers to redox reactions at the interfaces and self-alignment of energy levels leading to efficient charge transfer.
Bunch-Free Electroless-Etched Si Nanowire Array
Authors: Li Chuanbo , Fobelets K. , Tymieniecki M. S. , Hamayun M. , Durrani Z. A. K. , Green M.
Published: April 2011

Surface tension and Van der Waals bonding occur during electroless-chemical-etching of Si nanowire (NW) arrays and result in the bunching of the tops of the Si NWs. Different methods including the addition of ethanol during etching, freeze drying and post-RIE treatment, are examined to reduce the size of the NW bundles. The addition of a small volume of ethanol in the etch solution reduce the surface tension and bunching. Freeze drying was found to decrease the size of the NW bunches down to a few micrometers. Post-RIE etching efficiently reduces the size of NW bunches while also slimming the NWs.
Zinc Oxide (ZnO) Nanostructures for Photoelectrochemical Water Splitting Application
Authors: Shet Sudhakar
Published: April 2011

We have investigated the synthesis of ZnO nanostructures and their influence on photoelectrochemical response for water splitting application. A porous ZnO nanocoral structure synthesized using two step process provides a large surface area, superior light trapping, and an excellent pathway for carrier transport, resulted in a significantly increased PEC response compared to the compact ZnO thin films. We have also deposited ZnO nanorods. We found that the presence of N2 in the growth ambient help to promote the formation of aligned nanorods at high substrate temperature of 500°C, resulting in the significantly enhanced PEC response, compared to ZnO films. We investigated the presence of optimum N2 to Ar ratio in the deposition ambient, which promotes the formation of well aligned ZnO nanorods.
Citric Acid Assisted Sol-Gel Synthesis and Photoluminescence Characteristics of CaAl1.8Y0.2-xO4: xTb Nanoparticles
Authors: Taxak Vinod B. , Khatkar Satyender P. , Han Sang-Do , Kumar Mukesh
Published: April 2011

A novel green light emitting nano-sized phosphor, Tb3+ doped CaAl1.8Y0.2-xO4:xTb3+ was synthesized using citric acid assisted sol-gel process. Comparing with traditional material processing techniques, sol-gel process is a relatively simple method. The advantages of low temperature solution base process have been exploited to produce nano particles and the phase transformation involved in the pure homogeneous mixture formation. Synthesis conditions such as calcinations temperature and citric acid concentration are varied in order to determine the exact optimum conditions for synthesizing CaAl1.8Y0.2-xO4:xTb3+ nano particles with superior optical properties and smaller particle size. The nano crystals obtained through sol-gel method was characterized by using scanning electron microscopy (SEM), X-ray diffraction (XRD) technique and photoluminescence (PL) spectra. The predominant green colour from magnetic dipole transition 5D4 → 7F5 of Tb3+ was located at 543 nm.
Simulation of the Plasma Gas Condensation Based Synthesis and Extinction Spectra of Gold Nanoparticles
Authors: Bhattacharya Neelanjan , Das Biswajit
Published: April 2011

Nanoparticles can be synthesized using solution based or using ultra high vacuum based methods. Das et al.,[1] have already demonstrated nanoparticles of copper on solid state substrates using "plasma gas condensation", a vacuum based synthesis approach. This paper reports the simulation results for the synthesis of gold nanoparticles using plasma gas condensation and a study of their optical properties. The simulations as per [2] for process parameter control for the synthesis of gold nanoparticles using plasma gas condensation are discussed. The interaction of the nanoparticles with light is then studied. The electric field induced at the metal dielectric interface, which is relevant for SERS devices, is also calculated for different sizes of nanoparticles.
Development of Gold Coated Superparamagnetic Iron Oxide Nanoparticles for Nitroreductase Delivery
Authors: Cude Matthew P. , Gwenin Chris D.
Published: April 2011

Directed enzyme prodrug therapies (DEPT) currently suffer from inherent problems associated with localising and retaining enzymes at tumours. Superparamagnetic iron oxide nanoparticles (SPION) have been synthesised (≈10 nm) and surface functionalised with gold by direct reduction and by attachment of pre-synthesised Au seeds; these Au-SPION sols are stable in aqueous solution and are susceptible to magnetic manipulation. We have genetically modified the nitroreductase (NTR) yfkO from Bacillus Licheniformis to include a sequence of 12 cysteine residues, this modified NTR retains activity with CB1954 and has been immobilised onto gold via the 12 Au-S bonds. The yfkO-cys12 can therefore be immobilised with controlled orientation onto the Au-SPION to allow a magnetically directed enzyme prodrug therapy (MDEPT) to be developed; creating a novel strategy to target and localise prodrug activation to cancer tumour sites using magnetism.
Surface Modification of Cobalt Chromium Alloy via Phosphonic Acid Organic Nanosized Thin Films
Authors: Bhure Rahul , Abdel-Fattah Tarek M. , Bonner Carl , Hall Joseph C. , Mahapatro Anil
Published: April 2011

To address critical challenges with the use of Co-Cr alloy, a common metal alloy used in biomedical applications we demonstrated the formation of phosphonic acid organic nanosized thins films on Co-Cr alloy. X-ray photoelectron spectroscopy (XPS) determined the surface atomic composition before and after film deposition. The presence of phosphorous 'P' after deposition indicated presence of organic film formation. Similarly, changes in surface hydrophobicity as indicated by contact angle measurements suggested organic thin film formation.
In-Vitro Corrosion Inhibition of Magnesium Alloy via Organic Nanocoatings
Authors: Matos Negrón Taína D. , Abdel-Fattah Tarek M. , Bonner Carl , Mahapatro Anil
Published: April 2011

Magnesium alloy has been gaining interest for its potential biomedical applications as a biodegradable / bioabsorbable metallic implant. However its major disadvantage for biomedical applications is its low corrosion resistance especially in physiological environments. We demonstrate the formation of organic nano-coatings to control the bio-corrosion of Mg alloy. X-ray photoelectron spectroscopy (XPS) determined the surface atomic composition before and after film deposition. The presence of phosphorous "P" after deposition indicated the presence of organic film formation. Similarly, changes in surface hydrophobicity as indicated by contact angle measurements suggested organic thin film formation. Preliminary, In-Vitro corrosion behavior in PBS solutions indicated the effectiveness of these coatings to control the in vitro corrosion of Mg alloy
Nanotechnology and Microbial Electrochemistry for Environmental Remediation
Authors: Johnson Ashley , Merilis Giorvanni , Hastings Jason , Palmer M. Elizabeth , Fitts Jeffrey , Chidambaram Dev
Published: April 2011

Clostridia can synthesize catalytic nanoparticles in-situ at the zone of treatment. In essence, the microbial surface becomes the support for the catalyst, thus maintaining their high surface area. Concomitantly, microbes generate electron donors that cause reduction of contaminants. Current groundwater treatment technologies rely on delivering pre-formed catalytic nanoparticles into groundwater treatment zones and the addition of expensive molecular hydrogen to above ground pump and treat systems; two shortcomings that are overcome in this one-step process.
Exploration of Electric-Field Effects in Solid State Ionic Devices
Authors: Blackburn Bryan M. , Wachsman E. D.
Published: April 2011

This work explored the effect of localized electric fields on the performance of solid-state ionic devices. This was accomplished through the use of field electrodes, which created an electric field without leaking charge to the electrochemical cell. This is a significant distinction from fields generated with a direct bias including electrochemically promoted or NEMCA (Non-Faradaic Electrochemically Modified Catalytic Activity) enhanced cells. To investigate these field effects, we utilized a potentiometric gas sensor as a model device. We found that indirectly generated fields can improve device performance. For example, we have seen more than a 20X increase in NOx sensitivity. In this work, we compare planar sensor results, core and valence level photoelectron spectroscopy measurements, and other past surface science evidence to explore the origin of these effects. Our method for actively controlling ionic device performance can potentially be applied to gas sensors, fuel cells, gas separation membranes, and chemical reactors.
In Situ Spectroscopic Measurements of Local Potentials and Electrochemically Active Regions on Operating Solid Oxide Cells
Authors: Zhang Chunjuan , Grass Michael E. , DeCaluwe Steven C. , Liu Zhi , Bluhm Hendrik , Hussain Zahid , Jackson Gregory S. , Eichhorn Bryan W.
Published: April 2011

Ambient pressure X-ray photoelectron spectroscopy was used to detect rigid shifts in photoelectron kinetic energies and material chemical states for operating solid oxide electrochemical cells. The kinetic energy shifts directly correspond to the surface electric potentials and therefore can be used to detect the local potentials / potential losses for operating cells. The ceria valence state changes under applied biases relative to equilibrium conditions (at open circuit voltage) reveal the electrochemically active regions ~150 μm away from the current collectors for ceria thin film electrodes. The results provide fundamental mechanistic information about the active length scales in ceria electrodes, the surface reaction kinetics, charge transport, as well as activities for oxidation and electrolysis on operating solid oxide electrochemical cells.