bluuebunny/crossref_metadata_2025 huggingface dataset:
Integration of Ozonation and an Anaerobic Sequencing Batch Reactor (AnSBR) for the Treatment of Cherry Stillage
Authors: Álvarez Pedro M. , Beltrán Fernando J. , Rodríguez Eva M.
Published: October 2005

Cherry stillage is a high strength organic wastewater arising from the manufacture of alcoholic products by distillation of fermented cherries. It is made up of biorefractory polyphenols in addition to readily biodegradable organic matter. An anaerobic sequencing batch reactor (AnSBR) was used to treat cherry stillage at influent COD ranging from 5 to 50 g/L. Different cycle times were selected to test biomass organic loading rates (OLRB), from 0.3 to 1.2 g COD/g VSS·d. COD and TOC efficiency removals higher than 80% were achieved at influent COD up to 28.5 g/L but minimum OLRB tested. However, as a result of the temporary inhibition of acetogens and methanogens, volatile fatty acids (VFA) noticeably accumulated and methane production came to a transient standstill when operating at influent COD higher than 10 g/L. At these conditions, the AnSBR showed signs of instability and could not operate efficiently at OLRB higher than 0.3 g COD/g VSS·d. A feasible explanation for this inhibition is the presence of toxic polyphenols in cherry stillage. Thus, an ozonation step prior to the AnSBR was observed to be useful, since more than 75% of polyphenols could be removed by ozone. The integrated process was shown to be a suitable treatment technology as the following advantages compared to the single AnSBR treatment were observed: greater polyphenols and color removals, higher COD and TOC removal rates thus enabling the process to effectively operate at higher OLR, higher degree of biomethanation, and good stability with less risk of acidification.
Stochastic Modeling ofS. cerevisiaeInactivation by Supercritical CO2
Authors: Spilimbergo S. , Mantoan D.
Published: October 2005

Pasteurization ofS. cerevisiaein a simple substrate with supercritical CO2was performed at 36 °C on a laboratory multibatch apparatus of a total volume of 150 mL. The pressure values ranged from 100 to 300 bar. The results show a clear dependence between inactivation ratio and increase of pressure. A mathematical modeling of the process was exploited to fit the experimental evidences: inactivation curves were analyzed using a stochastic model based on the multihit model (1). The nonlinear survival curve shows a shoulder and a tail which represent the lag and the resistant phase, respectively. The meaning of the nonlinear relationship between inactivation ratio and time is also discussed; the effect of pressure on the values assumed by the parameters of the model proposed was investigated.
Cell‐Free Production of Aggregation‐Prone Proteins in Soluble and Active Forms
Authors: Kang Sang‐Hyeon , Kim Dong‐Myung , Kim Hyo‐Jin , Jun Soo‐Youn , Lee Ki‐Young , Kim Hye‐Jin
Published: October 2005

We have developed an efficient cell‐free protein synthesis system for the production of soluble and active eukaryotic proteins that are predominantly produced as inclusion bodies in bacteria. S30 extracts (indicating the supernatant of cell homogenate when centrifuged at 30,000g) for cell‐free protein synthesis were prepared from Escherichia coli that was modified to overexpress a set of chaperones (GroEL/ES or DnaK/J‐GrpE) and disulfide isomerase (leader sequence‐free mature DsbC expressed in the cytoplasm). The solubility and biological activity concentration (biological activity per unit volume of cell‐free protein synthesis reaction mixture) of the protein synthesized by the new cell‐free protein synthesis system showed a dramatic improvement. Solubility enhancement was most dramatic with the existence of DnaK/J‐GrpE. It shows that the co‐translational interaction with DnaK/J‐GrpE prior to folding trial is important in maintenance of the aggregation‐prone protein in a folding‐competent soluble state. For maximizing the biological activity concentration of the expressed protein, the additional presence of GroEL/ES and DsbC was required. When human erythropoietin was expressed in the developed cell‐free protein synthesis system including endogenously overexpressed chaperones and/or DsbC, the biological activity concentration of erythropoietin was enhanced by 700%. It implies that the post‐translational folding and disulfide bond reshuffling as well as co‐translational folding are important in acquiring functionally active protein from cell‐free expression system. This is the first report of using S30 extracts including endogenously overexpressed chaperones and/or disulfide isomerase for the efficient production of soluble and active proteins in cell‐free protein synthesis. This new cell‐free protein synthesis system was capable of introducing much larger amounts of chaperones and disulfide isomerase compared to a conventional method that supplements them separately. The developed cell‐free protein synthesis system supported efficient expression of the eukaryotic proteins in soluble and active forms without the need of any exogenous addition or coexpression of folding effectors.
Design and Testing for a Nontagged F1‐V Fusion Protein as Vaccine Antigen against Bubonic and Pneumonic Plague
Authors: Powell Bradford S. , Andrews Gerard P. , Enama Jeffrey T. , Jendrek Scott , Bolt Chris , Worsham Patricia , Pullen Jeffrey K. , Ribot Wilson , Hines Harry , Smith Leonard , Heath David G. , Adamovicz Jeffrey J.
Published: October 2005

A two‐component recombinant fusion protein antigen was re‐engineered and tested as a medical counter measure against the possible biological threat of aerosolized Yersinia pestis. The active component of the proposed subunit vaccine combines the F1 capsular protein and V virulence antigen of Y. pestis and improves upon the design of an earlier histidine‐tagged fusion protein. In the current study, different production strains were screened for suitable expression and a purification process was optimized to isolate an F1‐V fusion protein absent extraneous coding sequences. Soluble F1‐V protein was isolated to 99% purity by sequential liquid chromatography including capture and refolding of urea‐denatured protein via anion exchange, followed by hydrophobic interaction, concentration, and then transfer into buffered saline for direct use after frozen storage. Protein identity and primary structure were verified by mass spectrometry and Edman sequencing, confirming a purified product of 477 amino acids and removal of the N‐terminal methionine. Purity, quality, and higher‐order structure were compared between lots using RP‐HPLC, intrinsic fluorescence, CD spectroscopy, and multi‐angle light scattering spectroscopy, all of which indicated a consistent and properly folded product. As formulated with aluminum hydroxide adjuvant and administered in a single subcutaneous dose, this new F1‐V protein also protected mice from wild‐type and non‐encapsulated Y. pestis challenge strains, modeling prophylaxis against pneumonic and bubonic plague. These findings confirm that the fusion protein architecture provides superior protection over the former licensed product, establish a foundation from which to create a robust production process, and set forth assays for the development of F1‐V as the active pharmaceutical ingredient of the next plague vaccine.
Aqueous Extraction of Recombinant Human Proinsulin from Transgenic Maize Endosperm
Authors: Farinas Cristiane S. , Leite Adilson , Miranda Everson A.
Published: October 2005

Different plant species have been used as systems to produce recombinant proteins. Maize is a crop considered to have a large potential to produce high levels of recombinant proteins and is the host for the recombinant proteins from plants currently available on the market. In the development of a plant system to produce a recombinant proteins it is important to consider the costs related to downstream processing. Also, the steps necessary to achieve the protein purity required will be highly influenced by the quality of the extract obtained. In this study, we analyzed aqueous extracts from the endosperm of transgenic maize expressing recombinant human proinsulin (rhProinsulin). A study of the effects of the variables pH and ionic strength on the extraction efficiency was carried out using experimental design and response surface methodology. Besides the concentration of the recombinant protein, the characteristics of the extracts were evaluated in terms of concentration of native components (proteins, carbohydrates, and phenolic compounds) and extract filterability. The highest rhProinsulin concentration (97.33 ng/mL) was found with a 200 mM NaCl pH 10.0 extraction solution. Under this experimental condition the concentrations of total soluble proteins, carbohydrates, and phenolics were 2.01 mg/mL, 2.21 mg/mL, and 0.11 mmol/L, respectively.
Laccase‐Mediated Remazol Brilliant Blue R Decolorization in a Fixed‐Bed Bioreactor
Authors: Palmieri Gianna , Giardina Paola , Sannia Giovanni
Published: October 2005

A crude laccase mixture preparation from Pleurotus ostreatus cultures supplemented with copper and ferulic acid was used to decolorize the anthraquinonic dye Remazol Brilliant Blue R (RBBR). Performance of this enzymatic system was tested, and a maximum of 70% decolorization was achievable under optimal conditions. The crude preparation was immobilized by entrapment in copper alginate beads attaining 65% yield of laccase activity. Stability of the immobilized laccases was remarkably increased in comparison with that of the free enzyme preparation. Efficiency of the immobilized system was evaluated during stepwise dye additions in batch operations. Under the best conditions, 70% RBBR decolorization was achieved even after 20 cycles, although decolorization time exponentially increased after the 10th cycle. Different fixed‐bed bioreactors were prepared and analyzed in continuous decolorization processes. The best performance was obtained by decreasing the amount of enzyme loaded and by improving laccase retention using chitosan‐coated alginate beads.
Production of Biodiesel by Lipase‐Catalyzed Transesterification of Vegetable Oils: A Kinetics Study
Authors: Al‐Zuhair Sulaiman
Published: October 2005

Kinetics of production of biodiesel by enzymatic methanolysis of vegetable oils using lipase has been investigated. A mathematical model taking into account the mechanism of the methanolysis reaction starting from the vegetable oil as substrate, rather than the free fatty acids, has been developed. The kinetic parameters were estimated by fitting the experimental data of the enzymatic reaction of sunflower oil by two types of lipases, namely, Rhizomucor miehei lipase (RM) immobilized on ion‐exchange resins and Thermomyces lanuginosa lipase (TL) immobilized on silica gel. There was a good agreement between the experimental results of the initial rate of reaction and those predicted by the proposed model equations, for both enzymes. From the proposed model equations, the regions where the effect of alcohol inhibition fades, at different substrate concentrations, were identified. The proposed model equation can be used to predict the rate of methanolysis of vegetable oils in a batch or a continuous reactor and to determine the optimal conditions for biodiesel production.
Zusammenhänge zwischen rezeptiver Selbstdarstellungskompetenz und Leistung im Assessment Center
Authors: Preckel Daniel , Schüpbach Heinz
Published: October 2005

Zusammenfassung. Laborexperimentelle Studien zur Konstruktvalidität des Assessment Centers (AC) weisen darauf hin, dass Teilnehmende im AC besser beurteilt werden, wenn sie die von den Beobachtern beurteilten Anforderungen korrekt erkennen und ihr Verhalten im Sinne einer Selbstdarstellung darauf ausrichten. Im Fokus der vorliegenden Studie stand die Frage, ob sich der Zusammenhang zwischen Erkennensfähigkeit der AC-Teilnehmenden und den Beobachterurteilen auch unter den Realbedingungen der betrieblichen eignungsdiagnostischen Praxis nachweisen lässt. Die Stichprobe bestand aus 72 Bewerbern, die ein eintägiges AC in einem international tätigen Unternehmen der opto-elektronischen Industrie durchliefen. Es konnten signifikante Zusammenhänge zwischen Erkennensfähigkeit und Beobachterurteilen über vier verschiedene AC-Übungen hinweg gefunden werden. Die Erkennensfähigkeit blieb intraindividuell über die Übungen hinweg relativ stabil und erwies sich als unabhängig von kognitiven Fähigkeiten und Persönlichkeitsfaktoren.
Halo and mirror instabilities in the presence of finite Larmor radius effects
Authors: Pokhotelov O. A. , Balikhin M. A. , Sagdeev R. Z. , Treumann R. A.
Published: October 2005

The fully kinetic theory of low‐frequency electromagnetic modes in high‐β plasma is developed accounting for finite ion‐Larmor radius effects (FLR) in non‐Maxwellian space plasmas. The most general linear mirror mode dispersion relation is derived for arbitrary velocity distributions in the fully kinetic limit. Closer inspection shows that this dispersion relation describes two different instabilities. The first one corresponds to the classical mirror instability on the slow mode branch including FLR effects. Its growth rate attains a maximum at wavelengths the order of the ion gyroradius. Furthermore, if the plasma is mirror stable, i.e., when the condition for the mirror instability is not satisfied, another instability arises in the presence of a halo on the tail of the ion distribution. We term this new instability “halo instability.” It grows complementary to the mirror instability on the fast mode branch. It arises under conditions when the ratio of halo and thermal velocities exceeds some well‐defined critical value.
Subtidal inner‐shelf circulation near Point Conception, California
Authors: Cudaback Cynthia N. , Washburn Libe , Dever Ed
Published: October 2005

We discuss connections between inner‐shelf and mid‐shelf circulation near Point Conception, California, as well as the wind forcing of inner‐shelf circulation. Point Conception marks the southern edge of a major upwelling zone that extends from Oregon to central California. The coastline makes a sharp eastward turn at Point Conception, and the Santa Barbara Channel to the east is generally assumed to be an upwelling shadow. Consistent with this regional division, inner‐shelf currents are strongly correlated with wind north of Point Conception, but not in the Santa Barbara Channel. One exception to this generalization is a location in the Santa Barbara Channel, near a pass that cuts through the coastal mountains, where local winds have a dominant cross‐shore component and directly drive cross‐shore currents over the inner shelf. Inner‐shelf currents in the Santa Barbara Channel, when compared with mid‐shelf currents in that area, are weaker, but strongly correlated. By contrast, inner‐shelf currents north of Point Conception show a far greater incidence of poleward flow than is seen over the mid‐shelf in that area. Poleward flow events, lasting 1–5 days, transport warm water from the Santa Barbara Channel around Point Conception to the central California coast. These events are associated with relaxation of the generally equatorward wind, but not always with mid‐shelf flow reversals.
Temperature dependence of atmospheric moisture lifetime
Authors: Kennett E. J. , Toumi R.
Published: October 2005

In this study, the temperature dependence of atmospheric moisture lifetime is investigated using the European Centre for Medium‐Range Weather Forecasts 40‐year Reanalysis (ERA40) dataset. ERA40 shows that atmospheric moisture lifetimes can vary by greater than a factor of 4 within the column. Globally, the shortest lifetimes occur at temperatures of about −40°C, with mean lifetimes of just over a day at this level. Lifetimes derived independently from aircraft microphysical measurements in cirrus clouds confirm the rapid loss of moisture at about −40°C. This can be understood to result from changes in the rate of nucleation and size distribution of ice particles with decreasing temperature. A similar temperature dependence is observed in water vapor scale height, with relative humidity increasing with decreasing temperature below about −40°C. The variability of atmospheric moisture lifetime with temperature is found to be a fundamental microphysical control on the distribution of water vapor.
Evaluation of the distribution of subtropical free tropospheric humidity in AMIP‐2 simulations using METEOSAT water vapor channel data
Authors: Brogniez H. , Roca R. , Picon L.
Published: October 2005

In the framework of the Atmospheric Model Intercomparison Project (AMIP) phase 2, we have established a diagnostic of the free tropospheric humidity (FTH) distribution using METEOSAT data over the 1984–1995 period for 14 climate models. The methodology of evaluation follows a two step “model‐to‐satellite” approach. First the raw METEOSAT “Water Vapor” radiances are simulated from the model profiles of temperature and humidity using the RTTOV‐7 radiative transfer model. Second, the radiances are converted into FTH using the same coefficients as in the satellite product offering a direct comparison. The analysis is focused on the dry subtropical areas observed by METEOSAT: the Eastern Mediterranean and the tropical South Atlantic Ocean. Most of the models reproduce the observed seasonal cycle both in terms of phasing and magnitude, despite an overall moist bias. A few models are in close agreement with the satellite data. The magnitude of the satellite estimated inter‐annual variability is also generally captured by models. Again, a small subset of models shows close agreement with the observations. This comparison suggests general improvements of the models with respect to the AMIP‐1 simulations.
Cycle 20 solar wind modulation of galactic cosmic rays: Understanding the challenge
Authors: Ahluwalia H. S.
Published: October 2005

It is well known that time variations of galactic cosmic rays for cycle 20 (1964–1976) challenge our understanding of the heliospheric dynamics and the physical processes involved in causing observed modulations. Several interesting questions have been raised over the years. We attempt to provide some plausible answers based on analyses of cosmic ray data obtained with detectors on the ground, on balloons, and on satellites; median rigidity of response of these detectors to the cosmic ray spectrum covers a range of rigidities (R) from 1 to 70 GV. In particular, we explore the observed correlation between hourly rates of neutron monitors and the time series of the product of solar wind velocity (V) and interplanetary magnetic field intensity (B) at Earth's orbit. Local convection is identified as a contributor to “steps” in cosmic ray time variations near Earth and in the outer heliosphere. The amplitude of 11‐year modulation varies as 1/R; data do not support the concept of “transition” rigidity for modulation. We argue that heliosheath‐related modulation effects are minimal at Earth's orbit at R > 3 GV. Heuristic considerations suggest that the space‐dependent part of the diffusion coefficient should vary as 1/B (not 1/B2). We relate modulation function to the product BV, suggesting it plays a significant role in the solar modulation of cosmic rays.
Borehole temperatures and tree rings: Seasonality and estimates of extratropical Northern Hemispheric warming
Authors: Harris Robert N. , Chapman David S.
Published: October 2005

We construct an extratropical reduced temperature–depth profile for land areas north of 20°N latitude from the global borehole temperature database compiled for climate reconstruction. The mean reduced temperature profile compares well with a time series constructed from an initial baseline temperature (0.6° ± 0.1°C) and the last 140 years of gridded annual surface air temperature data diffused into the ground. This analysis yields a root‐mean‐square misfit of only 15 mK and indicates warming of 1.1°C over the past 500 years. In contrast, a tree ring analysis from the same area (Briffa et al., 2001) indicates considerably less warming over the same time period. The recognition that tree rings correlate most strongly with warm season temperatures (April–September), while boreholes reflect annual temperatures, offers an explanation for the discrepancy in warming estimates. This analysis yields a reconstruction of surface temperature over the past 500 years that is consistent with both the borehole and tree ring analysis and also provides an estimate of long‐term cold season temperature. We estimate that continental extratropical Northern Hemisphere annual and cold season (October–March) temperatures have warmed by 0.2° ± 0.1°C and 0.3° ± 0.3°C, respectively, between 1500 and 1856, prior to the start of the instrumental surface air temperature record.
Carbon and oxygen isotope ratios of tree ring cellulose along a precipitation transect in Oregon, United States
Authors: Roden John S. , Bowling David R. , McDowell Nate G. , Bond Barbara J. , Ehleringer James R.
Published: October 2005

The carbon and oxygen isotopic compositions of tree ring cellulose were examined for trees along a precipitation gradient in western Oregon, United States. Two years of cellulose from four sites dominated by coniferous forests ranging in precipitation from 227 to 2129 mm were sampled in conjunction with studies that measured the δ18O and δ13C of ecosystem respiration. The mean tree ring cellulose δ13C varied from −22.1 to −26.3‰ among sites and showed enrichment with decreasing water availability across the transect. The δ13C in cellulose varied across the precipitation transect in a similar pattern to the δ13C of leaf and root tissues as well as ecosystem respiration, although tree ring cellulose was enriched in 13C by over 3‰ compared to other organic matter components. The mean tree ring cellulose δ18O varied from 28.1 to 30.3‰. However, trends of cellulose δ18O change with water availability were obscured by differences in stem water δ18O. When calculated as deviation from stem water (δ18Ocellulose − δ18Ostem water) the differences in evaporative enrichment between sites was more pronounced (range of 9.6‰). The limited observed variation in tree ring cellulose δ18O of field grown trees despite large site difference in stem and leaf water δ18O across the transect agreed with predictions from a mechanistic model. Tree ring records of cellulose δ18O may provide useful proxy information regarding humidity and site water balance especially if combined with δ13C records that also vary with plant water status.
From Hypothesis-Testing Psychology to Procedure-Testing Psychologic
Authors: Smedslund Jan
Published: October 2005

Psychologists do not analyze the conceptual relations between their independent and dependent variables. Hence, they fail to recognize that the plausibility of their hypotheses stems from the conceptual relatedness of the variables. The outcome is research that appears to test hypotheses but really tests only procedures, because the hypotheses involve conceptually related variables and are necessarily true. Domains in which this has been demonstrated are discussed. Psychologic is an axiomatic system intended to formulate the psychologically relevant conceptual relationships embedded in language and is an instrument for describing, explaining, predicting, and controlling intrapersonal and interpersonal processes.
A Conceptual Framework for Examining Adolescent Identity, Media Influence, and Social Development
Authors: Te'Neil Lloyd Blake
Published: October 2005

The adolescent identity, media, and sociocognitive schema (AIMSS) framework offers a theoretical understanding of adolescent consumption and cognitive processing of media entertainment. Review and integration of mass communication theory, developmental theory, and ecological theory serves as the conceptual foundation. The framework outlines linkages between media exposure and adolescent development, in particular adolescent identity formation and social competence. A key contribution of the model is consideration of the positive and negative aspects of adolescent cognition and behavioral functioning. The present article offers several recommendations for testing the utility of the AIMSS framework.
Applying Persuasion Strategies to Alter HIV-Relevant Thoughts and Behavior
Authors: Devos-Comby Loraine , Salovey Peter
Published: October 2005

Health communication strategies are at the core of both mass media campaigns and public health interventions conducted at the community level concerning the prevention of HIV/AIDS. They are often nested in complex contexts that prevent us from being able to identify the persuasive impact of a specific message. The authors attempt to account for an array of factors contributing to the persuasiveness of messages about HIV. The aim is to synthesize the psychological literature on persuasion and thus provide a conceptual framework for understanding message effects in HIV communications. This discussion concerns fear appeals, message framing, tailoring, cultural targeting, and additional factors pertaining to the message, source, and channel of the communication. Whenever possible, recommendations for further research are formulated.
Dynamics in a room-temperature ionic liquid: A computer simulation study of 1,3-dimethylimidazolium chloride
Authors: Bhargava B. L. , Balasubramanian S.
Published: October 2005

The transport properties and solvation dynamics of model 1,3-dialkylimidazolium chloride melt at 425K is studied using molecular-dynamics simulations. Long trajectories of a large system have been generated and quantities such as the self-diffusion coefficient of ions, shear viscosity, and ionic conductivity have been calculated. Interestingly, the diffusion of the heavier cation is found to be faster than the anion, in agreement with experiment. The interaction model is found to predict a higher viscosity and lower electrical conductivity compared to experimental estimates. Analysis of the latter calculations points to correlated ion motions in this melt. The solvation time correlation function for dipolar and ionic probes studied using equilibrium simulations exhibits three time components, which include an ultrafast (subpicosecond) part as well as one with a time constant of around 150ps. The ultrafast solvent relaxation is ascribed to the rattling of anions in their cage, while the slow component could be related to the reorientation of the cations as well as to ion diffusion.
Dynamics of polymers in a particle-based mesoscopic solvent
Authors: Mussawisade K. , Ripoll M. , Winkler R. G. , Gompper G.
Published: October 2005

We study the dynamics of flexible polymer chains in solution by combining multiparticle-collision dynamics (MPCD), a mesoscale simulation method, and molecular-dynamics simulations. Polymers with and without excluded-volume interactions are considered. With an appropriate choice of the collision time step for the MPCD solvent, hydrodynamic interactions build up properly. For the center-of-mass diffusion coefficient, scaling with respect to polymer length is found to hold already for rather short chains. The center-of-mass velocity autocorrelation function displays a long-time tail which decays algebraically as (Dt)−3∕2 as a function of time t, where D is the diffusion coefficient. The analysis of the intramolecular dynamics in terms of Rouse modes yields excellent agreement between simulation data and results of the Zimm model for the mode-number dependence of the mode-amplitude correlation functions.
Hierarchical structure of the energy landscape of proteins revisited by time series analysis. II. Investigation of explicit solvent effects
Authors: Alakent Burak , Camurdan Mehmet C. , Doruker Pemra
Published: October 2005

Time series analysis tools are employed on the principal modes obtained from the Cα trajectories from two independent molecular-dynamics simulations of α-amylase inhibitor (tendamistat). Fluctuations inside an energy minimum (intraminimum motions), transitions between minima (interminimum motions), and relaxations in different hierarchical energy levels are investigated and compared with those encountered in vacuum by using different sampling window sizes and intervals. The low-frequency low-indexed mode relationship, established in vacuum, is also encountered in water, which shows the reliability of the important dynamics information offered by principal components analysis in water. It has been shown that examining a short data collection period (100ps) may result in a high population of overdamped modes, while some of the low-frequency oscillations (<10cm−1) can be captured in water by using a longer data collection period (1200ps). Simultaneous analysis of short and long sampling window sizes gives the following picture of the effect of water on protein dynamics. Water makes the protein lose its memory: future conformations are less dependent on previous conformations due to the lowering of energy barriers in hierarchical levels of the energy landscape. In short-time dynamics (<10ps), damping factors extracted from time series model parameters are lowered. For tendamistat, the friction coefficient in the Langevin equation is found to be around 40–60cm−1 for the low-indexed modes, compatible with literature. The fact that water has increased the friction and that on the other hand has lubrication effect at first sight contradicts. However, this comes about because water enhances the transitions between minima and forces the protein to reduce its already inherent inability to maintain oscillations observed in vacuum. Some of the frequencies lower than 10cm−1 are found to be overdamped, while those higher than 20cm−1 are slightly increased. As for the long-time dynamics in water, it is found that random-walk motion is maintained for approximately 200ps (about five times of that in vacuum) in the low-indexed modes, showing the lowering of energy barriers between the higher-level minima.
Heavier alkali-metal monosulfides (KS, RbS, CsS, and FrS) and their cations
Authors: Lee Edmond P. F. , Wright Timothy G.
Published: October 2005

The heavier alkali-metal monosulfides (KS, RbS, CsS, and FrS) have been studied by high-level ab initio calculations. The RCCSD(T) method has been employed, combined with large flexible valence basis sets. All-electron basis sets are used for potassium and sulfur, with effective core potentials being used for the other metals, describing the core electrons. Potential-energy curves are calculated for the lowest two neutral and cationic states: all neutral monosulfide species have a Π2 ground state, in contrast with the alkali-metal monoxide species, which undergo a change in the electronic ground state from Π2 to Σ+2 as the group is descended. In the cases of KS, RbS, and CsS, spin-orbit curves are also calculated. We also calculate potential-energy curves for the lowest Σ−3 and Π3 states of the cations. From the potential-energy curves, spectroscopic constants are derived, and for KS the spectroscopic results are compared to experimental spectroscopic values. Ionization energies, dissociation energies, and heats of formation are also calculated; for KS, we explore the effects of relativity and basis set extrapolation on these values.
Gyro-Landau fluid equations for trapped and passing particles
Authors: Staebler G. M. , Kinsey J. E. , Waltz R. E.
Published: October 2005

A new system of gyro-Landau fluid (GLF) equations for tokamak plasmas is presented. The new equations include both trapped particles, which can average the Landau resonance, and passing particles which do have a Landau resonance. The trap GLF (TGLF) model is unrestricted in trapped fraction or perpendicular wave number of the electrostatic perturbation. The linearly unstable eigenmodes of the TGLF equations include low-frequency trapped ion modes all the way up to high-frequency electron temperature gradient driftwaves. Extensive benchmarking of the linear TGLF eigenmodes with a large database of gyrokinetic linear stability calculations verifies that the TGLF model is accurate over the full range of plasma parameters tested.
Thermal broadening of the J-band in disordered linear molecular aggregates: A theoretical study
Authors: Heijs D. J. , Malyshev V. A. , Knoester J.
Published: October 2005

We theoretically study the temperature dependence of the J-band width in disordered linear molecular aggregates, caused by dephasing of the exciton states due to scattering on vibrations of the host matrix. In particular, we consider inelastic one- and two-phonon scatterings between different exciton states (energy-relaxation-induced dephasing), as well as the elastic two-phonon scattering of the excitons (pure dephasing). The exciton states follow from numerical diagonalization of a Frenkel exciton Hamiltonian with diagonal disorder; the scattering rates between them are obtained using the Fermi golden rule. A Debye-type model for the one- and two-phonon spectral densities is used in the calculations. We find that, owing to the disorder, the dephasing rates of the individual exciton states are distributed over a wide range of values. We also demonstrate that the dominant channel of two-phonon scattering is not the elastic one, as is often tacitly assumed, but rather comes from a similar two-phonon inelastic scattering process. In order to study the temperature dependence of the J-band width, we simulate the absorption spectrum, accounting for the dephasing-induced broadening of the exciton states. We find a power-law (Tp) temperature scaling of the effective homogeneous width, with an exponent p that depends on the shape of the spectral density of the host vibrations. In particular, for a Debye model of vibrations, we find p≈4, which is in good agreement with the experimental data on J aggregates of pseudoisocyanine [I. Renge and U. P. Wild, J. Phys. Chem. A, 101, 7977 (1997)].
Combining configurational entropy and self-concentration to describe the component dynamics in miscible polymer blends
Authors: Cangialosi D. , Schwartz G. A. , Alegría A. , Colmenero J.
Published: October 2005

We provide a new approach to describe the component segmental dynamics of miscible polymer blends combining the concept of chain connectivity, expressed in terms of the self-concentration, and the Adam-Gibbs model. The results show an excellent agreement between the prediction of our approach and the experimental data. The self-concentrations obtained yield length scales between 1 and 3.2nm depending on the temperature, the flexibility of the polymer, expressed in terms of the Kuhn segment, and its concentration in the blends, at temperatures above the glass transition range of the blend.
New theoretical insight into the interactions and properties of formic acid: Development of a quantum-based pair potential for formic acid
Authors: Roszak Szczepan , Gee Richard H. , Balasubramanian Krishnan , Fried Laurence E.
Published: October 2005

We performed ab initio quantum-chemical studies for the development of intra- and intermolecular interaction potentials for formic acid for use in molecular-dynamics simulations of formic acid molecular crystal. The formic acid structures considered in the ab initio studies include both the cis and trans monomers which are the conformers that have been postulated as part of chains constituting liquid and crystal phases under extreme conditions. Although the cis to trans transformation is not energetically favored, the trans isomer was found as a component of stable gas-phase species. Our decomposition scheme for the interaction energy indicates that the hydrogen-bonded complexes are dominated by the Hartree-Fock forces while parallel clusters are stabilized by the electron correlation energy. The calculated three-body and higher interactions are found to be negligible, thus rationalizing the development of an atom-atom pair potential for formic acid based on high-level ab initio calculations of small formic acid clusters. Here we present an atom-atom pair potential that includes both intra- and inter molecular degrees of freedom for formic acid. The newly developed pair potential is used to examine formic acid in the condensed phase via molecular-dynamics simulations. The isothermal compression under hydrostatic pressure obtained from molecular-dynamics simulations is in good agreement with experiment. Further, the calculated equilibrium melting temperature is found to be in good agreement with experiment.
On the accuracy of correlation-energy expansions in terms of local increments
Authors: Stoll Hermann , Paulus Beate , Fulde Peter
Published: October 2005

The incremental scheme for obtaining the energetic properties of extended systems from wave-function-based ab initio calculations of small (embedded) building blocks, which has been applied to a variety of van der Waals-bound, ionic, and covalent solids in the past few years, is critically reviewed. Its accuracy is assessed by means of model calculations for finite systems, and the prospects for applying it to delocalized systems are given.
Influence of initial conditions on homogeneous nucleation kinetics in a closed system
Authors: Kožíšek Zdeněk , Demo Pavel
Published: October 2005

The formation of nuclei of a new phase from the supersaturated mother phase in a closed system is studied. The depletion of the mother phase due to phase transition is taken into account. Basic kinetic equations describing such process are solved numerically to determine the number density of nuclei of newly forming phase and nucleation rate. It is shown that in contrary to the standard nucleation model, when the depletion of the mother phase is not taken into account, the initial size distribution of the clusters affects considerably the nucleation process at higher supersaturations. Our model starts with the equilibrium size distribution of clusters up to various cluster sizes in the undercritical region. At lower supersaturation the formation of nuclei is similar to the standard model because of the low depletion of the mother phase. At higher supersaturation, the depletion of the mother phase plays an important role and some extremal value appears at the size distribution of nuclei, which is not observed in the standard model. The extremum in the size distribution is not a consequence of the coalescence process itself, but it is caused rather by the depletion of the mother phase during the phase transformation.
Reactivity enhancement of ultracold O(P3)+H2 collisions by van der Waals interactions
Authors: Weck P. F. , Balakrishnan N.
Published: October 2005

The role of van der Waals forces in O(P3)+H2(υ=1,j=0) collisions is investigated theoretically at low and ultralow temperatures. Quantum scattering calculations have been performed for zero total angular momentum using the lowest London-Eyring-Polanyi-Sato double-polynomial A″3 potential-energy surface reported by [Rogers et al., J. Phys. Chem. A 104, 2308 (2000)] and its recent BMS1 and BMS2 extensions developed by [Brandão et al., J. Chem. Phys. 121, 8861 (2004)] which provide a more accurate treatment of the van der Waals interaction. Our calculations show that van der Waals forces strongly influence chemical reactivity at ultracold translational energies. The presence of a zero-energy resonance for the BMS1 surface is found to enhance reactivity in the ultracold regime and shift the Wigner threshold to lower temperatures.
Submarine granular flows down inclined planes
Authors: Cassar C. , Nicolas M. , Pouliquen O.
Published: October 2005

Submarine flows of granular material down a rough inclined plane are experimentally investigated. We focus on the dense flow regime when the whole sediment layer is flowing down the slope and when no deposition nor entrainment occurs. In this regime, steady uniform flows are observed for which we systematically measure the depth-averaged velocity, the thickness, and the excess pore pressure for different inclinations and different flow rates. The experimental measurements are analyzed within a theoretical approach inspired by recent results obtained for dry granular flows. The basic assumption of the model is that the constitutive law obtained in the dry case still holds for submarine flow, if one substitutes the inertial time scale coming into play in the rheology by a viscous time scale. The agreement between the measurements and the theory supports this assumption.
Capacitive effects in quasi-steady-state voltage and lifetime measurements of silicon devices
Authors: Cuevas A. , Recart F.
Published: October 2005

When measuring I-V characteristics and carrier lifetimes in quasi-steady-state (QSS) conditions, it is important to consider the time dependence of the charge due to excess carriers within the device. This paper shows that the space-charge region present in pn-junction devices and in many lifetime test structures can produce a significant capacitive effect when measuring the low voltage and low carrier density range of QSS I-V curves. Both computer modeling and experiments show that the junction capacitance is particularly significant in the case of low-resistivity silicon wafers, but it can also be noticeable in intermediate and high-resistivity samples. The paper demonstrates that the static I-V characteristics can be accurately reconstructed using a simple analytical model for the space-charge region. It thus fills a gap in the understanding of the low injection range of QSS voltage and lifetime measurements.
Laser-induced fluorescence imaging of plants using a liquid crystal tunable filter and charge coupled device imaging camera
Authors: Saito Yasunori , Matsubara Tomohiro , Koga Tomoya , Kobayashi Fumitoshi , Kawahara Takuya D. , Nomura Akio
Published: October 2005

We developed a laser-induced fluorescence imaging system for plant monitoring use, with which it was possible to make an image at any wavelength between 430 and 750nm. The excitation source for the fluorescence was a cw ultraviolet laser diode with 398nm, and the detector was an image-intensified charge coupled device. A liquid crystal tunable filter was used as the fluorescence wavelength selection device. All of the system performance including the wavelength tuning was electrically controlled, so that it could be operated with no mechanical vibration noise. The fluorescence images of a coffee tree leaf obtained at 440, 530, 685, and 740nm clearly showed a distribution pattern of the fluorescence intensity over the leaf. The pattern reflected the different physiological statuses of the plant. Advantages of the imaging system were experimentally discussed on a point of detection of inhomogeneous physiological activities over a plant leaf.
An alternative isolation of tungsten tips for a scanning tunneling microscope
Authors: Abelev E. , Sezin N. , Ein-Eli Y.
Published: October 2005

Experimental results obtained from electrochemical preparation of tungsten followed by a novel insulating technique are reported. An additional effective method for insulation of the electrochemically etched W tips based on cathophoretic paint deposition is described. The cathophoretic paint deposition isolation method was found to be highly reproducible, forming an isolated stable film in both aqueous and nonaqueous organic solvents.
Magnetic phase transition in YCo3B2 studied by magnetic resonance
Authors: Sigalov O. , Shames A. I. , Caspi E. N. , Dubman M. , Ettedgui H. , Goren S. D. , Shaked H.
Published: October 2005

Magnetic-susceptibility measurements, nuclear magnetic resonance (NMR) of B11, and electron magnetic-resonance (EMR) spectra of YCo3B2 were measured as a function of the temperature. The temperature dependence of the magnetic susceptibility showed a lambda-shaped anomaly at 150K. Whereas upon cooling, a shift in the resonance position of the NMR and EMR spectra is observed at 150K, marking the emergence of an internal magnetic field. The quadrupolar splitting of the NMR lines showed a marked discontinuity at 150K. The (T1T)−1∕2 values were found to be independent of temperature for T>175K, and to increase sharply upon cooling for T<150K. The intensity of the EMR line which is independent of temperature for T>160K is also found to increase markly upon cooling below 150K. All these effects are discussed and it is proposed that YCo3B2 undergoes a magnetic ordering phase transition at 150K.
The role of the chemical nature of implanted species on quenching and recovery of photoluminescence in ion-irradiated porous silicon
Authors: Jacobsohn L. G. , Cooke D. W. , Bennett B. L. , Muenchausen R. E. , Nastasi M.
Published: October 2005

The effects of ion irradiation on porous Si (po-Si) photoluminescence (PL) have been investigated. Specimens were progressively irradiated with H+ and He+ ions followed by PL measurements. After the final irradiation, which resulted in total PL quenching, PL recovery was monitored for more than 200 days. The behavior of both PL quenching and recovery was correlated to the amount of retained irradiation-induced damage, determined by channeling spectrometry measurements, and to the chemical nature of the implanted species. Quenching was attributed to the generation of defects that create nonradiative states within the gap, while recovery was attributed to the passivation of these defects by atmospheric exposure. H+ irradiation is approximately five times more efficient in quenching PL and leads to approximately four times lower recovery rate than He+ irradiation. This behavior is attributed to the formation of stable H-defect complexes.
Improved optical chamber for small measuring cells with temperature control
Authors: Barón Máximo , Guaraglia Carlos L. , Lichtenstein Gabriel
Published: October 2005

An improved optical chamber is described containing a Chatelain prism with controlled heating and temperature control. It consists of placing the prism between two copper plates heated through a miniaturized device that creates a hot air current inside a small acrylic chamber. The heater is a power transistor controlled by an operational amplifier that creates a 3 h ramp generated digitally through firmware in a microcontroller. The cell temperature, obtained through a thermistor, can be controlled to ±0.1K.
Theory of the plasma sheath in a magnetic field parallel to the wall
Authors: Tskhakaya D. D. , Shukla P. K. , Eliasson B. , Kuhn S.
Published: October 2005

The plasma-wall transition (PWT) layer in a magnetic field parallel to the wall is investigated with a two-fluid approach, where the continuity and momentum equations for electrons and ions are used to describe the semi-bounded plasma, whereas the background gas of neutral particles is assumed to be uniformly distributed. The equations include ionization, recombination and charge exchange processes. The magnetic field is parallel to the confining wall, which is assumed to have a potential different from the one in the bulk plasma. A linear analysis of the PWT layer reveals two distinct length scales, namely the short Debye screening length scale and the much longer collisional length modified by the magnetic field. It is found that the ionization and recombination processes are important to connect the PWT layer to the bulk plasma, which is characterized by a balance between ionization and recombination. The PWT layer is here treated as a unit, without a priori splitting into sheath and presheath sublayers. The nonlinear set of equations is solved numerically to obtain the profiles of the electrostatic potential, the densities, and the velocity components. Near the wall, where the electron velocity is large, the Lorentz force and collisions lead to an electron density distribution significantly different from the Boltzmann one.