bluuebunny/crossref_metadata_2025 huggingface dataset:
Fatigue of survivors following cardiac surgery: Positive influences of preoperative prayer coping
Authors: Ai Amy L. , Wink Paul , Shearer Marshall
Published: April 2012

Objectives. Fatigue symptoms are common among individuals suffering from cardiac diseases, but few studies have explored longitudinally protective factors in this population. This study examined the effect of preoperative factors, especially the use of prayer for coping, on long‐term postoperative fatigue symptoms as one aspect of lack of vitality in middle‐aged and older patients who survived cardiac surgery.

Method. The analyses capitalized on demographics, faith factors, mental health, and on medical comorbidities previously collected via two‐wave preoperative interviews and standardized information from the Society of Thoracic Surgeons’ national database. The current participants completed a mailed survey 30 months after surgery. Two hierarchical regressions were performed to evaluate the extent to which religious factors predicted mental and physical fatigue, respectively, after controlling for key demographics, medical indices, and mental health.

Results. Preoperative prayer coping, but not other religious factors, predicted less mental fatigue at the 30‐month follow‐up, after controlling for key demographics, medical comorbidities, cardiac function (previous cardiovascular intervention, congestive heart failure, left ventricular ejection fraction, New York Heart Association Classification), mental health (depression, anxiety), and protectors (optimism, hope, social support). Male gender, preoperative anxiety, and reverence in secular context predicted more mental fatigue. Physical fatigue increased with age, medical comorbidities, and preoperative anxiety. Including health control beliefs in the model did not eliminate this effect.

Conclusions. Prayer coping may have independent and positive influences on less fatigue in individuals who survived cardiac surgery. However, future research should investigate mechanisms of this association.
Graphene as a diffusion barrier for Al and Ni/Au contacts on silicon
Authors: Kim Hong-Yeol , Lee Chongmin , Kim Jihyun , Ren Fan , Pearton S. J.
Published: April 2012

The insertion of chemically vapor deposited graphene layers between Al metallization and Si substrates and between Au and Ni metal layers on Si substrates is shown to provide a significant reduction in spiking and intermixing of the metal contacts and reaction with the Si, where the bilayer graphene was transferred to the samples after the Cu-foil was etched. The graphene prevents reaction between Al and Si up to the temperatures of 700 °C and the intermixing of Au and Ni up to the temperatures of at least 600 °C. The outstanding performance of the graphene as a metal diffusion barrier will be very useful to improve the stability of the metallizations at elevated temperatures.
Quantification with a dedicated breast PET/CT scanner
Authors: Bowen Spencer L. , Ferrero Andrea , Badawi Ramsey D.
Published: April 2012

Purpose:

Dedicated breast PET/CT is expected to have utility in local staging, surgical planning, monitoring of therapy response, and detection of residual disease for breast cancer. Quantitative metrics will be integral to several such applications. The authors present a validation of fully 3D data correction schemes for a custom built dedicated breast PET/CT (DbPET/CT) scanner via18F‐FDG phantom scans.

Methods:

A component‐based normalization was implemented, live‐time was estimated with a multicomponent model, and a variance reduced randoms estimate was computed from delayed coincidences. Attenuation factors were calculated by using a CT based segmentation scheme while scatter was computed using a Monte Carlo (MC) simulation method. As no performance standard currently exists for breast PET systems, custom performance tests were created based on prior patient imaging results. Count‐rate linearity for live‐time and randoms corrections was measured with a decay experiment for a solid polyethylene cylinder phantom with an offset line source. A MC simulation was used to validate attenuation correction, a multicompartment phantom with asymmetric activity distribution provided an assessment of scatter correction, and image uniformity after geometric and detector normalization was measured from a high count scan of a uniform cylinder phantom. Raw data were reconstructed with filtered back projection (FBP) after Fourier rebinning. To quantify performance absolute activity concentrations, contrast recovery coefficients and image uniformity were calculated through region of interest analysis.

Results:

The most significant source of error was attributed to mispositioning of events due to pile‐up, presenting in count‐related axial and transaxial nonuniformities that were not corrected for with the normalization method used here. Within the range of singles counts observed during clinical trials residual error after applying all corrections was comparable to that of a commercial whole body PET/CT system.

Conclusions:

The results suggest that DbPET/CT is capable of producing quantitative images under the operating conditions expected during patient imaging.
Evolving treatment plan quality criteria from institution‐specific experience
Authors: Ruan D. , Shao W. , DeMarco J. , Tenn S. , King C. , Low D. , Kupelian P. , Steinberg M.
Published: April 2012

Purpose:

The dosimetric aspects of radiation therapy treatment plan quality are usually evaluated and reported with dose volume histogram (DVH) endpoints. For clinical practicality, a small number of representative quantities derived from the DVH are often used as dose endpoints to summarize the plan quality. National guidelines on reference values for such quantities for some standard treatment approaches are often used as acceptance criteria to trigger treatment plan review. On the other hand, treatment prescription and planning approaches specific to each institution warrants the need to report plan quality in terms of practice consistency and with respect to institution‐specific experience. The purpose of this study is to investigate and develop a systematic approach to record and characterize the institution‐specific plan experience and use such information to guide the design of plan quality criteria. In the clinical setting, this approach will assist in (1) improving overall plan quality and consistency and (2) detecting abnormal plan behavior for retrospective analysis.

Methods:

The authors propose a self‐evolving methodology and have developed an in‐house prototype software suite that (1) extracts the dose endpoints from a treatment plan and evaluates them against both national standard and institution‐specific criteria and (2) evolves the statistics for the dose endpoints and updates institution‐specific criteria.

Results:

The validity of the proposed methodology was demonstrated with a database of prostate stereotactic body radiotherapy cases. As more data sets are accumulated, the evolving institution‐specific criteria can serve as a reliable and stable consistency measure for plan quality and reveals the potential use of the “tighter” criteria than national standards or projected criteria, leading to practice that may push to shrink the gap between plans deemed acceptable and the underlyingunknown optimality.

Conclusions:

The authors have developed a rationale to improve plan quality and consistency, by evolving the plan quality criteria from institution‐specific experience, complementary to national standards. The validity of the proposed method was demonstrated with a prototype system on prostate stereotactic body radiotherapy (SBRT) cases. The current study uses direct and indirect DVH endpoints for plan quality evaluation, but the infrastructure proposed here applies to general outcome data as well. The authors expect forward evaluation together with intelligent update based on evidence‐based learning, which will evolve the clinical practice for improved efficiency, consistency, and ultimately better treatment outcome.
Using spatial information about recurrence risk for robust optimization of dose‐painting prescription functions
Authors: Bender Edward T.
Published: April 2012

Purpose:

To develop a robust method for deriving dose‐painting prescription functions using spatial information about the risk for disease recurrence.

Methods:

Spatial distributions of radiobiological model parameters are derived from distributions of recurrence risk after uniform irradiation. These model parameters are then used to derive optimal dose‐painting prescription functions given a constant mean biologically effective dose.

Results:

An estimate for the optimal dose distribution can be derived based on spatial information about recurrence risk. Dose painting based on imaging markers that are moderately or poorly correlated with recurrence risk are predicted to potentially result in inferior disease control when compared the same mean biologically effective dose delivered uniformly. A robust optimization approach may partially mitigate this issue.

Conclusions:

The methods described here can be used to derive an estimate for a robust, patient‐specific prescription function for use in dose painting. Two approximate scaling relationships were observed: First, the optimal choice for the maximum dose differential when using either a linear or two‐compartment prescription function is proportional to R, where R is the Pearson correlation coefficient between a given imaging marker and recurrence risk after uniform irradiation. Second, the predicted maximum possible gain in tumor control probability for any robust optimization technique is nearly proportional to the square of R.
Inverse‐planned modulated‐arc total‐body irradiation
Authors: Kirby Neil , Held Mareike , Morin Olivier , Fogh Shannon , Pouliot Jean
Published: April 2012

Purpose:

To develop a simple and robust method for inverse‐planned total‐body irradiation (TBI) that is more comfortable and has better dose homogeneity than the conventional forward‐planned techniques and that can be delivered in a standard‐sized treatment vault.

Methods:

Modulated‐arc TBI (MATBI) utilizes an arc of static open‐field beams to irradiate patients as they lay on a stationary couch beneath the gantry, with cerrobend blocks suspended over organs at risk to provide shielding. Prior to treatment, full‐body computed tomography (CT) images are acquired of each patient and imported into thePINNACLE3 planning system, which modulates the monitor units for the open‐field beams to optimize the body dose uniformity. The volume of the body within 10% of the prescription dose, V(±10), is used as a metric to evaluate the dose uniformity. For comparison to MATBI, the dose distribution of a conventional forward‐planned treatment is also calculated. Quality assurance measurements are acquired before treatment by delivering the plans to a phantom and during treatment with an ionization chamber inside a buildup block, placed between the patient's ankles.

Results:

For MATBI, the achieved values of V(±10) were 75.8%, 90.2%, 84.6%, and 79.8% compared to 60.3%, 77.4%, 65.6%, and 68.5% for the conventional TBI technique, respectively. The pretreatment ion chamber measurements in the phantom had an average error of 1.2%. Those acquired during treatment had larger errors, with most points being within 3% of predictions.

Conclusions:

MATBI provides better dose uniformity and comfort than the conventional forward‐planned TBI techniques. In addition, the technique can be implemented on most linacs, in standard‐sized vaults, without the use of a translating couch.
Comparative economic analyses of patient safety improvement strategies in acute care: a systematic review
Authors: Etchells Edward , Koo Marika , Daneman Nick , McDonald Andrew , Baker Michael , Matlow Anne , Krahn Murray , Mittmann Nicole
Published: April 2012

Background

The objective was to systematically review comparative economic analyses of patient safety improvements in the acute care setting.

Methods

A systematic review of 15 patient safety target conditions and six improvement strategies was conducted. The authors searched the published literature through Medline (2000–November 2011) using the following search terms for costs: ‘costs and cost analysis’, ‘cost-effectiveness’, ‘cost’ and ‘financial management, hospital’. The methodological quality of potentially relevant studies was appraised using Cochrane rules of evidence for clinical effectiveness in quality improvement, and standard economic methods.

Results

The authors screened 2151 abstracts, reviewed 212 potentially eligible studies, and identified five comparative economic analyses that reported a total of seven comparisons based on at least one clinical effectiveness study of adequate methodological quality. Pharmacist-led medication reconciliation to prevent potential adverse drug events dominated (lower costs, better safety) a strategy of no reconciliation. Chlorhexidine for vascular catheter site care to prevent catheter-related bloodstream infections dominated a strategy of povidone-iodine for catheter site care. The Keystone ICU initiative to prevent central line-associated bloodstream infections was economically dominant over usual care. Detecting surgical foreign bodies using standard counting compared with a strategy of no counting had an incremental cost of US$1500 (CAN$1676) for each surgical foreign body detected. Several safety improvement strategies were less economically attractive, such as bar-coded sponges for reducing retained surgical sponges compared with standard surgical counting, and giving erythropoietin to reduce transfusion requirements in critically ill patients to avoid one transfusion-related adverse event.

Conclusions

Five comparative economic analyses were found that reported a total of seven comparisons based on at least one effectiveness study of adequate methodological quality. On the basis of these limited studies, pharmacist-led medication reconciliation, the Keystone ICU intervention for central line-associated bloodstream infections, chlorhexidine for vascular catheter site care, and standard surgical sponge counts were economically attractive strategies for improving patient safety. More comparative economic analyses of such strategies are needed.
A GENERALIZATION OF TODA LATTICES AND THEIR BI-HAMILTONIAN STRUCTURES
Authors: GENG XIANGUO , LI FANG , XUE BO
Published: April 2012

A hierarchy of new nonlinear differential-difference equations associated with fourth-order discrete spectral problem is proposed, in which a typical member is a generalization of the Toda lattice equation. The bi-Hamiltonian structures for this hierarchy are obtained with the help of trace identity.
A THEORETICAL STUDY OF NONLINEAR CAPACITANCE OF MAMMALIAN OUT HAIR CELL BY A NONTRANSPORTING FIVE-STATE MODEL
Authors: ZHANG LEI , ZHANG YONG , KIM CHUL KOO , LEE KONG-JU-BOCK
Published: April 2012

Understanding the nonlinear capacitance (NLC) of prestin and outer hair cell (OHC) is important for exploring the activity of mammalian cochlea. After introducing a nontransporting five-state model of the OHC motor which is the tetramer of prestin, we obtain the peak of the NLC of OHC and the peak shift of the NLC as functions of the concentration of the intracellular Cl- anions. By employing the same model, we calculate the frequency dependence of the NLC as well. The model results both in equilibrium state and of the frequency dependence agree with the experimental observations. Accordingly, it suggests that the introduced five-state model is a candidate for exploring the NLC of both OHC and prestin.
DEFECT FORMATION AND MAGNETIC PROPERTIES OF COPPER DOPED ZnO NANOWIRES
Authors: SHI LI-BIN
Published: April 2012

Theoretical calculation based on density functional theory (DFT) and generalized gradient approximation (GGA) has been carried out in studying defect formation energies, ionization energies and magnetic properties of copper doped ZnO nanowires (NW). It is found from formation energy calculation that n-type Cu-doped ZnO NW is non-FM and p-type Cu-doped ZnO NW could be FM. The results show that total energies of FM coupling are lower than those of AFM coupling for majority of 12 configurations, indicating that the FM coupling between Cu atoms is more stable than AFM coupling. The FM stability is interpreted by Cu 3d energy level coupling. In addition, zinc and oxygen vacancies affecting FM coupling is also discussed. It is found that FM coupling can be tuned by zinc and oxygen vacancies.
THE HELIX-COIL TRANSITION IN A DOUBLE-STRANDED POLYNUCLEOTIDE AND THE TWO-DIMENSIONAL RANDOM WALK
Authors: HAYRAPETYAN G. N. , MOROZOV V. F. , PAPOYAN V. V. , POGHOSYAN S. S. , PRIEZZHEV V. B.
Published: April 2012

The helix-coil transition in a double-stranded homopolynucleotide is considered. The new approach to the melted loops account is proposed. The relative distance between the corresponding monomers of two polymer chains is modeled by the two-dimensional random walk on the square lattice. Returns of the random walk to the origin describe the formation of hydrogen bonds between complementary units. To take into account the interaction of monomers inside the chains, we consider various regimes of return to the origin. One of them involves two competing interactions and demonstrates a nontrivial sharp denaturation transition. The rich phase behavior of the double-stranded homopolynucleotide is discussed in terms of the proposed approach.
THE QUANTUM HALL EFFECT IN GRAPHENE
Authors: CEA PAOLO
Published: April 2012

We investigate the quantum Hall effect in graphene. We argue that in graphene in presence of an external magnetic field there is dynamical generation of mass by a rearrangement of the Dirac sea. We show that the mechanism breaks the lattice valley degeneracy only for the n = 0 Landau levels and leads to the new observed ν = ±1 quantum Hall plateaus. We suggest that our result can be tested by means of numerical simulations of planar Quantum Electro Dynamics with dynamical fermions in an external magnetic fields on the lattice.
UNCERTAIN AND STOCHASTIC FINANCIAL MODELS WITH MULTIPLE DELAYS
Authors: MIRCEA GABRIELA , NEAMŢU MIHAELA , BUNDĂU OLIVIA , OPRIŞ DUMITRU
Published: April 2012

This paper studies the autonomous uncertain and stochastic systems with multiple delays, which describe a financial system involving the interest rate, the investment demand and the price index. For the deterministic model associated to the uncertain financial system, we set the conditions for the existence of the delay parameter value for which the model displays a Hopf bifurcation. For the stochastic system, we identify the differential equations for the mean value as well as for the square mean value. The last part of the paper includes numerical simulations and conclusions.
HYPERCHAOS IN A MEMRISTOR-BASED MODIFIED CANONICAL CHUA'S CIRCUIT
Authors: FITCH ANDREW L. , YU DONGSHENG , IU HERBERT H. C. , SREERAM VICTOR
Published: April 2012

After the successful solid state implementation of the memristor, memristor-based circuits have received a lot of attention. In this paper, a memristor with cubic nonlinear characteristics is employed in the modified canonical Chua's circuit. A systematic study of hyperchaotic behavior in this circuit is performed with the help of nonlinear tools such as Lyapunov exponents, phase portraits and bifurcation diagrams. In particular, an imitative memristor circuit is examined to reveal the construction of hyperchaotic attractors.
LIMIT CYCLES FOR A CLASS OF CONTINUOUS PIECEWISE LINEAR DIFFERENTIAL SYSTEMS WITH THREE ZONES
Authors: LIMA MAURÍCIO FIRMINO SILVA , LLIBRE JAUME
Published: April 2012

In this paper, we consider a class of planar continuous piecewise linear vector fields with three zones. Using the Poincaré map, we show that these systems admit always a unique limit cycle, which is hyperbolic.
A COMPLEX NETWORK PERSPECTIVE OF WORLD STOCK MARKETS: SYNCHRONIZATION AND VOLATILITY
Authors: LIU XIAO FAN , TSE CHI K.
Published: April 2012

This paper studies the cross-correlations of 67 stock market indices in the past 5 years. In order to capture the interaction of the stock markets, we propose to take a complex network approach to analyzing the interdependence of the individual stock markets. Specifically, stock markets are considered as network nodes, and the network links (weights of links) are defined by the cross-correlations between market indices over a period of time (time window). Thus, the resulting network provides information about the interdependence of individual markets, with the network links representing the extents to which the markets are correlated. If we allow the time window to move in forward time and construct a network for each time window over a long period of time, we are able to capture the dynamics of the network. In our study, all networks are constructed from raw data of market indices, and our aim is to investigate how network properties can be used to infer market behavior. By examining the variation of the network parameters as time elapses, we show that stock markets of different countries have time-varying interaction, and that developed markets tend to demonstrate similar behavior while emerging markets are statistically independent of each other. Furthermore, we observe synchronization in the network of stock markets, which is an important universal property observed in many physical and man-made networks. Specifically, we show that stock markets of different countries generally behave in a synchronous manner when they experience fluctuation, which is especially notable in the developed markets. This work exposes the interdependence of stock markets in the world and proposes a complex network approach to identifying some salient global behavior of the interconnecting markets.
IRREVERSIBLE BIFURCATION PHENOMENON IN POWER-GRID CONNECTED CONVERTER SYSTEMS
Authors: WAN CHENG , HUANG MENG , TSE CHI K. , WONG SIU-CHUNG , RUAN XINBO
Published: April 2012

Three-phase voltage source converters (VSC) are commonly used to convert ac power from a three-phase grid to a regulated dc voltage with unity input power factor. The control of the VSC is normally achieved by an outer voltage feedback loop and a sinusoidal pulse-width-modulated (SPWM) inner current loop. However, the nonideal power grid and the presence of other interacting loads give rise to nonlinear operation and drive the VSC to enter an irreversible instability region. In this paper, an irreversible bifurcation phenomenon in a three-phase voltage-source converter connected to a power grid with an interacting load is reported. The converter can also be regarded as exhibiting a catastrophic bifurcation in which the input current expands to cause undesirable component stress. A large-signal analysis is adopted to identify the physical origin of the phenomenon and to locate the boundary of the instability.
CONVERGENCE ANALYSIS OF THE FINITE ELEMENT METHOD FOR A FUNDAMENTAL MODEL IN TURBULENCE
Authors: KAYA S. , MANICA C. C.
Published: April 2012

This report is concerned with the question of computing accurate approximations to the motion of large structures in turbulent flows. We choose a fundamental closure model used in Large Eddy Simulation and investigate how a simple finite element method can be used to compute discrete solutions. We determine that both stability and accuracy of the discretization depend strongly on how filtering is performed. A numerical example is provided that supports our theoretical findings.
ELASTIC FLOW WITH JUNCTIONS: VARIATIONAL APPROXIMATION AND APPLICATIONS TO NONLINEAR SPLINES
Authors: BARRETT JOHN W. , GARCKE HARALD , NÜRNBERG ROBERT
Published: April 2012

We consider stable semidiscrete approximations of parametrized curve networks for gradient flows of elastic type functionals. Here meaningful and relevant conditions at junction points, such as double and triple junctions, need to be derived and suitably discretized. Examples for double junction types are C0 attachment and C1 continuity. We develop strong and weak formulations for the elastic flow for curve networks with such junction points. For junctions with three or more curves, the conditions at the junctions are derived here for the first time. Possible applications include a simplified one-dimensional model of geometric biomembranes, as well as nonlinear splines in two and higher dimensions. The numerical results presented in this paper demonstrate the practicality of the introduced finite element approximations.
STRONG AND WEAK SEMICLASSICAL LIMIT FOR SOME ROUGH HAMILTONIANS
Authors: ATHANASSOULIS AGISSILAOS , PAUL THIERRY
Published: April 2012

We present several results concerning the semiclassical limit of the time-dependent Schrödinger equation with potentials whose regularity does not guarantee the uniqueness of the underlying classical flow. Different topologies for the limit are considered and the situation where two bicharacteristics can be obtained out of the same initial point is emphasized.
AN EFFECTIVE MASS MODEL FOR THE SIMULATION OF ULTRA-SCALED CONFINED DEVICES
Authors: BEN ABDALLAH NAOUFEL , JOURDANA CLÉMENT , PIETRA PAOLA
Published: April 2012

In this paper, we present the derivation and the simulation of an effective mass model, describing the quantum motion of electrons in an ultra-scaled confined nanostructure. Due to the strong confinement, the crystal lattice is considered periodic only in the one-dimensional transport direction and an atomistic description of the entire cross-section is given. Using an envelope function decomposition, an effective mass approximation is obtained. It consists of a sequence of one-dimensional device-dependent Schrödinger equations, one for each energy band, in which quantities retaining the effects of the confinement and of the transversal crystal structure are inserted. In order to model a gate-all-around field effect transistor, self-consistent computations include the resolution, in the whole domain, of a Poisson equation describing a slowly varying macroscopic potential. Simulations of the electron transport in a simplified one-wall carbon nanotube are presented.
Crossing boundaries, the influence of groundwater model boundaries and a method to join and split MODFLOW models
Authors: Black A. D. , Lewis R. T. , Grout M. W. , Witterick W. R.
Published: April 2012

Neighbouring groundwater models often have large areas of overlap to avoid boundary issues in hydrogeological assessments and such overlap or artificial boundaries can lead to inconsistent representations of aquifers and processes. This paper presents the aggregation of six adjacent models spanning East Anglia, England, into one model without internal boundaries. This study principally discusses the effect of, and difficulties arising from model edge boundaries. In addition, a review of conceptual and numerical discontinuities at model boundaries is included and a more consistent and robust modelling approach over the whole area is demonstrated. The large, joined model is used to delineate groundwater divides, assess their transient migration, review edge boundary implications for water balances and investigate abstraction impacts without the influence of internal static boundaries. Computer codes developed in conjunction with this study facilitate joining adjacent models and, conversely, splitting of the joined model back into models at the scale of the original component models using simulated groundwater divides, or to smaller submodels incorporating edge boundary conditions calculated from the parent model.
A national approach to groundwater modelling: developing a programme and establishing technical standards
Authors: Rushton K. R. , Skinner A. C.
Published: April 2012

In the 1970s regional groundwater modelling began to be used in support of many hydrogeological investigations in the UK. A number of the studies were concerned with groundwater development at a regional scale in conjunctive use schemes; elsewhere the effect of pumping from aquifers on river flows or the ingress of saline water was considered. Due to the limited power of digital computers at that time, special numerical codes were often prepared for individual projects, with consequent inefficiency and inconsistency of practice. However, by the mid 1990s the need to formalize and standardize groundwater modelling projects was recognized. The Environment Agency of England and Wales prepared a strategy to manage and monitor the projects. A Template Project Brief was prepared to define the many tasks involved in groundwater studies and to clarify the roles of contractor and client (Environment Agency). In addition Guidance Notes were prepared to disseminate procedures and techniques that had resulted in successful outcomes. This paper summarizes some of the earlier studies, provides information about the Project Brief and Guidance Notes and illustrates some critical issues in groundwater modelling by reference to two case studies.
Recharge estimation methodologies employed by the Environment Agency of England and Wales for the purposes of regional groundwater resource modelling
Authors: Quinn S. A. , Liss D. , Johnson D. , Van Wonderen J. J. , Power T.
Published: April 2012

Recharge calculations based on daily soil moisture balance models define the resource available for most regional-scale groundwater models used by the environmental regulator in England and Wales. A switch in recent years from the Penman–Grindley methodology to the Food and Agricultural Organization approach has improved the representation of soil properties in these calculations. A new Meteorological Office algorithm for calculating potential evapotranspiration inputs has also been adopted and rain-gauge data processing on individual models are currently being streamlined towards the use of nationally derived grids. A range of infiltration, bypass and runoff–recharge mechanisms have been conceptualized and modelled incorporating simple representation of unsaturated zone storage and flow processes. This paper reviews the recent changes adopted and considers future challenges.
Groundwater resource modelling for public water supply management in London
Authors: Jones M. A. , Hughes A. G. , Jackson C. R. , Van Wonderen J. J.
Published: April 2012

In London, groundwater abstractions for public supply are predominantly from the Chalk aquifer. However, water resource pressures put existing abstractions at risk and often require complex analysis to support new source development. Thames Water develops and uses regional groundwater models for such analysis to support communication with stakeholders such as the Environment Agency, the environmental regulator of England and Wales. Using two case studies, the importance of regional models as Thames Water assets is demonstrated. While Thames Water has developed regional models as a context for sub-catchment scale analysis of groundwater source development, they are subsequently used to address other issues. As a result, the models are updated regularly, enhancing both conceptual understanding and calibration. These models cost less than 1% of the capital cost of new water source schemes. However, as they are enhanced and applied more widely, the models accrue further value as active decision support tools. Regional model usage to investigate a range of local systems and interactions is of particular value to Thames Water. In this regard, it is important to appreciate and promote the clarity and consistency generated when stakeholder-specific issues can be analysed within an agreed regional model framework.
Study of the Influence of the Rare Earth Elements (Ce3+ and Ce4+) Concentration on the Siloxanes Coating Applied on the Copper Surface
Authors: Basho Érika N. , Sakai Rafael T. , Da Cruz Fabíola M. , De Melo Hercilio G. , Benedetti Assis V. , Suegama Patrícia H.
Published: April 2012

This work studied the influence of the rare earth (Ce3+ and Ce4+) elements concentration in polysiloxane films deposited on copper by dip-coating process, and evaluated their resistance in a 3.5 wt.% NaCl medium. Classical electrochemistry techniques were used as open circuit potential, polarization curves and electrochemical impedance spectroscopy. The results revealed that by adding low concentration of Ce4+ ions, the coating prevents the electrolyte uptake any longer retarding the substrate degradation consequently.
Influence of Benzoyl Peroxide (BPO) on Polysiloxane Thin Films Doped with Ce(III) onto Tin Coated Steel and Their Anticorrosion Properties
Authors: Da Cruz Fabíola M. , Suegama Patrícia H. , Fugivara Cecílio S. , Santilli Celso V. , Della Noce Rodrigo , Benedetti Assis V.
Published: April 2012

The influence of benzoyl peroxide (BPO) on the synthesis of polysiloxane thin films doped with Ce(III) deposited onto Sn coated steel as well as their anticorrosion properties are reported. The addition of BPO, whose role is polymerize the film, showed an increase in |Z| values due to the fact that augments the crossed link bonds and therefore improves the protective feature of the film. Ce(III) does not act in the polymerization process and thus is essential the addition of BPO to obtain more resistant polysiloxane films.
Study of the Corrosion of Buried Steel Grids of Electrical Power Transmission Towers
Authors: Klunk Marcos A. , De Oliveira Adriano A. , Furtado Gilnei G. , Knörnschild Gerhard , Dick Luis F.
Published: April 2012

The corrosion of metal structures in large facilities such as AC power transmission lines results in economic losses due to the necessary replacement of these structures and the interruption of power supply. To evaluate soil corrosion of the buried part of the structure the corrosion rate of AISI1020 steel samples was determined by weight loss measurements as a function of the exposure time to the soil close to a power transmission tower. The same measurements were made with samples which were connected to the tower while buried in the soil. By comparison of the two measurement series the influence of the AC power signal on soil corrosion can be studied.
Effect of Trivalent Chromium Based Treatment on the Protective Properties of Steel Coated with Polymeric Film
Authors: Queiroz Fernanda M. , Tomachuk Célia R. , Zumelzu Ernesto , De Melo Hercilio G. , Costa Isolda
Published: April 2012

Three main requirements are mandatory in order to achieve optimal quality in canned food: adequate processing of the product, definition of the preserving method, and a correct alloy for the deposit. Lacquer coatings are applied on food cans to enhance corrosion protection and also with decorative purposes. In this investigation, steel coated with a Cr3+ based treatment layer and polyethylene teraphtalate polymeric film (PET), applied by co- extrusion, was characterized by electrochemical impedance spectroscopy (EIS) measurements, in NaCl 0.5 M solution, to evaluate the coating corrosion resistance in this environment. The experimental results showed that this new material (tin free) has good corrosion resistance regardless of the porosity found in the polymeric film, indicating that it can be a non-polluting alternative to replace tinplate and hexavalent chromium conversion layer in the food industry, being compatible with the packed product.
Electrochemical Behavior of Electrogalvanized Steel with a Conversion Treatment at Room Temperature
Authors: Tomachuk Célia R. , Queiroz Fernanda M. , Costa Isolda
Published: April 2012

Conversion treatments applied on electrogalvanized steel are largely used for corrosion protection. Cr3+ based conversion treatment has been established as an alternative to Cr6+ treatments. However, commercially available baths operate at temperatures around 60 °C and use high concentrations of Cr3+ salts. In order to attend the world market demand for processes with low energy consumption and Green Technologies, a Cr3+ treatment has been developed with much lower contents of Cr3+ salts, about 80% lower, which operates at room temperature. The corrosion resistance of surface treated electrogalvanized steel in baths with two different concentrations of Cr3+ ions was evaluated by electrochemical impedance spectroscopy in chloride solution. The results showed that the surface treatment with low Cr3+concentration and carried out at room temperature, leads to better corrosion resistance in comparison to the commercial type, and it might be considered as a potential replacement for chromating treatments that have been increasingly banished from use.
Electrooxidation of the Reactive Orange 16 Dye Using Boron Doped Diamond and DSA Type Electrodes
Authors: Migliorini Fernanda L. , Alegre Marcela D. , Alves Suellen A. , Lanza Marcos R. , Baldan Mauricio R. , Ferreira Neidenei G.
Published: April 2012

The comparison of the efficiencies for boron-doped diamond (BDD) and for DSA-Cl2® type electrodes to degrade the reactive orange 16 (RO16) dye is presented. The results for the dye electrochemical degradation were investigated by spectroscopic techniques UV/VIS analysis, Total Organic Carbon (TOC), and High Performance Liquid Chromatography (HPLC). The BDD electrode showed the higher performance in the whole range of current densities studied for the color removal as well as in the mineralization of organic materials present in such dye.
Electrochemical Characterization and Evaluation of the Analytical Potentialities of Glassy Carbon Electrodes Modified with Extracted Lignin from Black (Kraft) Liquor
Authors: Buoro Rafael M. , Silva Robson P. , Bacil Raphael P. , Lima Antonio W. , Rabóczkay Tibor , Cides da Silva Luis C. , Serrano Silvia H.
Published: April 2012

The electrochemical behavior of Kraft Lignin Glassy Carbon Modified electrodes, GCE-LIG, was studied. The modified electrode was prepared by recovering the glassy carbon surfaces with 10 μL of 1.0 and 0.01 g L-1 lignin in DMF. The polymeric film produced showed electrochemical activity due the quinone / hydroquinone (Q/HQ) redox couple produced from lignin by a mechanism involving an electrochemical oxidation step followed by a coupled chemical reaction. The GCE-LIG is stable at negative potentials up to - 1.5 V in pH range of 2.0 to 8.0, but the lignin polymeric film is leached from the electrode surface at potentials higher than + 0.8 V. The modified electrodes showed resistive behavior, which increased with the film thickness. Another interesting characteristic of the GCE-LIG is its selectivity to coordination complexes since the electrochemical activity increases as function of the major complexes lability.
Electrochemical Treatment of Real Textile Industrial Effluent Using Diamond Electrode
Authors: Solano Sales Aline , Do Nascimento Brito Chrystiane , Ribeiro da Silva Djalma , Martínez-Huitle Carlos A.
Published: April 2012

In this work, a real effluent discharged by Brazilian textile industry, has been electrochemically treated using boron doped diamond (BDD) anode for removing chemical oxygen demand (COD) and colour. Preliminary experiments were performed under real discharged effluent conditions (pH, conductivity and COD) in order to verify the applicability of this treatment process. However, a partial elimination of COD and colour effluent were achieved, 12% and 21%, respectively. Therefore, new set of experiments were carried out where COD of textile effluent was completely reduced by applying 60 mA cm-2 in presence of Na2SO4 and NaCl; reducing the time of depuration and consequently, the costs, confirming the potential efficiency of this dyestuff treatment.
Electropolymerization Mechanism in Aqueous Solution of the Oxo-Manganese Complex Biomimicking of the Enzimatic Center Present on the Photosystem II
Authors: Martin Cibely S. , Teixeira Marcos F.
Published: April 2012

The [Mn4IVO5(terpy)4(H2O)2]6+ complex, show great potential for electrode modification by electropolymerization using cyclic voltammetry. The electropolymerization mechanism was based in the electronic transfer between dx2-y2 orbitals of the center metallic and pπ orbital of the ligand, which show great complexity of the system due to orbitals overlap present in octahedral complex of the metal-μ-oxo. The voltammetric behavior both in and after electropolymerization process were also discussed, where the best condition of electropolymerization was observed for low scan rate and 50 potential cycles. A study in ITO/glass electrode for better characterization of polymer was also performed.
Voltammetric Determination Of Sulfite Using Graphite Paste Electrode Modified with Nanoparticles of Copper Pentacyanonitrosylferrate
Authors: Do Carmo Devaney R. , Silvestrini Daniela R. , Cumba Loanda R. , Souza Marcelo M.
Published: April 2012

Copper Pentacyanonitrosylferrate (NCuNP) nanoparticles were prepared in formamide solvent. The material was characterized by Infrared (FTIR), X-Ray Diffraction (XRD) and Ultraviolet-Visible (UV-Vis) Spectroscopy. The Cyclic Voltammogram (CV) the modified graphite paste electrode with NCuNP exhibits two redox couples with (Eθ')1 = 0.29 and (Eθ')2 = 0.86 V attribute at Cu(I)/Cu(II) and Fe(II)(CN)5NO/Fe(III)(CN)5NO processes, respectively (KCl = 1.0 mol L-1; v = 20 mV s-1). The redox couple with (Eθ')2 presents an electrocatalytic response for sulfite. The modified graphite paste electrode gives a linear response of 7.0 × 10-4 to 3.0 × 10-2 mol L-1 (r = 0.998), for sulfite determination with Detection Limit (DL) of of 1.76 x10-3 mol L-1 and an amperometric sensitivity of 3.38 mA/mol L-1 and relative standard desviations ± 3% (n=3).
Preparation of PtSn/C Skeletal-Type Electrocatalysts for Ethanol Electro-Oxidation
Authors: Crisafulli Rudy , Oliveira Neto Almir , Linardi Marcelo , Vitorio Spinacé Estevam
Published: April 2012

PtSnCu/C electrocatalysts were synthesized with 20 wt% of metals loading and different Pt:Sn:Cu atomic ratios by borohydride reduction method using 2-propanol as solvent, H2PtCl6.6H2O, SnCl2.2H2O and CuCl2.2H2O as metals sources, NaBH4 as reducing agent and carbon black Vulcan XC72 as support. In a second step, the electrocatalysts were treated with nitric acid. The obtained materials were characterized by X-ray diffraction and EDX analysis. The electro-oxidation of ethanol was studied by chronoamperometry in acid medium at room temperature. The X-ray diffractograms of the as-synthesized electrocatalysts showed the typical face-centered cubic (FCC) structure of Pt and Pt alloys. After treatment with nitric acid the X-ray diffractrograms showed that the FCC structure was preserved and EDX analysis that Sn an Cu were partially removed. The results obtained by chronoamperometry showed for all electrocatalysts an increase of performance for ethanol electro-oxidation after acid treatment.
Voltammetric Determination of Captopril Employing Platinum Electrode Modiﬁed with Iron (III) Hexacyanoferrate (II) Film
Authors: Eleotério Izabel C. , Balbino Marco A. , De Oliveira Marcelo F.
Published: April 2012

Environment contamination with drugs even at concentrations in the order mg L-1 and ng L-1 culminates in environmental and public health problems because these substances are biologically active. For this reason, the pursuit of instrumental methods for the determination of these substances has been the main target of several investigators. Captopril, an antihypertensive drug employed for the treatment of heart failure, has been identified by means of electrochemical technique. To this end, a platinum electrode modified with an iron (III) hexacyanoferrate (II) film (Prussian blue) associated with the cyclic voltammetry mode has been utilized. Our results have furnished a linear correlation coefficient (r) of 0.998 with a standard deviation (SD) of 0.007 μA, a detection limit (based on the 3 SD/m ratio) in 7 µmol L-1, and a quantification limit (based on the relationship 10 SD/m) of 23.3 µmol L-1.
Spectroelectrochemical Study of the Hybrid between Vanadium Oxide and Carboxybenzylviologen for Application in Electrochromic Electrodes
Authors: De Oliveira Renato S. , Alves Wendel A. , Ponzio Eduardo A.
Published: April 2012

In this work, we describe the synthesis of a new organic-inorganic hybrid material, which is composed by 1,1'-bis(4-carboxybenzyl)-4,4'-bipyridine (carboxybenzylviologen) bromide and vanadium pentoxide xerogel for application in electrochromic electrodes. The presence of the viologen resulted in a stabilization of the electrochemical response of vanadium pentoxide xerogel and improvement in spectroelectrochemical properties. The hybrid presented good reversibility and cyclability during 100 cycles, electrochromic efficiency was 16 cm²C-¹, 92.7 % (410 nm) transmittance variation and 59.1 % color retention after 100 cycles of color changing.
Synthesis and Characterizations of LiSICON Li2Co2(MoO4)3 with Different Amounts of Starch
Authors: Marques Marcelo M. , Siqueira Júnior José M. , Resende Jackson A. , Leal Katia Z. , Ponzio Eduardo A.
Published: April 2012

This paper describes a simple procedure to synthesize materials with NASICON-like structures, using starch as a mild combustion fuel. The results of ICP-MS, x-ray and Raman spectroscopy present that the samples can be classified as a solid solution and isostructural to Li2Co2(MoO4)3. The analysis by x-ray diffraction shows that the increase on starch amount promotes crystallinity, leading to diffraction peaks more intense and better defined. Moreover, we can infer that the amount of starch increases substantially the material capacity (5 mAhg-1 to 52 mAhg-1), as well leads to a better definition of the redox peaks
Morphine and Clonidine Synergize to Ameliorate Low Back Pain in Mice
Authors: Tajerian Maral , Millecamps Magali , Stone Laura S.
Published: April 2012

Chronic low back pain (LBP) is a debilitating condition associated with signs of axial and radiating pain. In humans with chronic LBP, opioids are often prescribed with varying outcomes and a multitude of side effects. Combination therapies, in which multiple pharmacological agents synergize to ameliorate pain without similar potentiation of adverse reactions, may be useful in improving therapeutic outcome in these patients. The SPARC-null mouse model of low back pain due to disc degeneration was used to assess the effects of opioid (morphine) andα2-adrenergic agonist (clonidine) coadministration on measures of axial and radiating pain. The results indicate that systemic morphine and clonidine, coadministered at a fixed dose of 100 : 1 (morphine : clonidine), show a synergistic interaction in reversing signs of axial LBP, in addition to improving the therapeutic window for radiating LBP. Furthermore, these improvements were observed in the absence of synergy in assays of motor function which are indicative of side effects such as sedation and motor incoordination. These data show that the addition of low-dose systemic clonidine improves therapeutic outcome in measures of both axial and radiating pain. Combination therapy could be of enormous benefit to patients suffering from chronic LBP.
A Coarse-Grained Reconfigurable Architecture with Compilation for High Performance
Authors: Wan Lu , Dong Chen , Chen Deming
Published: April 2012

We propose afast data relay(FDR) mechanism to enhance existing CGRA (coarse-grained reconfigurable architecture). FDR can not only provide multicycle data transmission in concurrent with computations but also convert resource-demanding inter-processing-element global data accesses into local data accesses to avoid communication congestion. We also propose the supporting compiler techniques that can efficiently utilize the FDR feature to achieve higher performance for a variety of applications. Our results on FDR-based CGRA are compared with two other works in this field: ADRES and RCP. Experimental results for various multimedia applications show that FDR combined with the new compiler deliver up to 29% and 21% higher performance than ADRES and RCP, respectively.