bluuebunny/crossref_metadata_2025 huggingface dataset:
The First Encounter: Peasant Resistance to State Control of Grain in East China in the Mid-1950s
Authors: Li Huaiyin
Published: March 2006

Focusing on Dongtai and Songjiang counties in east China, this report examines peasant resistance to the “unified purchase and sale” programme in the 1950s. The heavy procurement burden on most households in the prosperous Songjiang county led to various forms of resistance from peasants that culminated in collective violence. In sharp contrast, the low procurement quota on a limited number of households in the impoverished Dongtai county only caused moderate resistance. In both counties, however, local government leaders faced the increasing inapplicability of the prevailing notion of “class line” to the new realities of rural disgruntlement. As this report demonstrates, in both counties, resistance to the state's grain programme came primarily from ordinary peasants rather than their class enemies of landlords and rich peasants. For the first time, the CCP felt the need to redefine peasant discontent under the socialist state as a new category, later known as “contradictions within the people,” which remains valid to date in official representations of rural disturbances.
Peptide-induced hyperactivation-like vigorous flagellar movement in starfish sperm
Authors: Shiba Kogiku , Tagata Tomoko , Ohmuro Junko , Mogami Yoshihiro , Matsumoto Midori , Hoshi Motonori , Baba Shoji A.
Published: March 2006

Asterosap, a sperm-activating peptide (SAP) from the starfish egg jelly coat, is diffusible and controls a cGMP-signalling pathway in starfish sperm in the same manner as resact, a potent chemoattracting SAP in sea urchins. This fact suggests that asterosap may serve as a chemoattractant like resact at concentrations with appropriate gradients. Since asterosap is one of three egg jelly components, which in concert induce the acrosome reaction, it is still worthwhile to evaluate how asterosap modulates sperm motility prior to this reaction. We analysed the flagellar movement of sperm of the starfish Aphelasterias japonica in artificial seawater (ASW) containing the asterosap isoform P15 at 1 μmol l−1. We found that sperm swim straighter with more symmetrical flagellar movement in P15 than in ASW, but without any significant difference in the flagellar beat frequency and the swimming velocity. The flagellar movement is, however, dramatically different between sperm firmly attached to the solid surface by the head in P15 and those attached in ASW: in P15 the flagellum bends to a greater extent, with higher curvature and with higher shear angle up to a right angle to the flagellar wave axis, and beats at an increased frequency. The vigorous flagellar movement of sperm, which can be activated when sperm are placed in high-load circumstances just as entering into a jelly layer, may increase propulsive forces and hydrodynamic resistances, allowing sperm to undergo the acrosome reaction as effectively as possible.
Nitric-oxide-dependent activation of pig oocytes: the role of the cGMP-signalling pathway
Authors: Petr J. , Rajmon R. , Chmelíková E. , Tománek M. , Lánská V. , Přibáňová M. , Jílek F.
Published: March 2006

Pig oocytes matured in vitro were parthenogenetically activated (78%) after treatment with 2 mM nitric oxide-donor (±)-S-nitroso-N-acetylpenicillamine (SNAP) for 24 h. Inhibition of soluble guanylyl cyclase with the specific inhibitors 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) or 6-anilino-5,8-quinolinequinone (LY83583) suppressed the SNAP-induced activation in a dose-dependent manner (23% of activated oocytes after treatment with 400 μM ODQ; 12% of activated oocytes after treatment with 40 μM LY83583). 8-Bromo-cyclic guanosine monophosphate (8-Br-cGMP), a phosphodiesterase-resistant analogue of cGMP, enhances the effect of suboptimal doses (0.1 or 0.5 mM) of the NO donor SNAP. DT3, a specific inhibitor of cGMP-dependent protein kinase (PKG, PKG), is also able to inhibit the activation of pig oocytes after NO donor treatment. Involvement of the cGMP-dependent signalling pathway is specific for NO-induced oocyte activation, because both the guanylyl cyclase inhibitor ODQ and the PKG inhibitor DT3 are unable to inhibit activation in oocytes treated with the calcium ionophore A23187. These data indicate that the activation of pig oocytes with an NO donor is cGMP-dependent and that PKG plays an important role in this mode of oocyte activation.
A potential relationship between the acrosome response characteristics of bovine spermatozoa and their in vitro fertilizing ability
Authors: Molnarova Zuzana , Machatkova Marie , Machal Ladislav , Horakova Jindra , Hanzalova Katerina
Published: March 2006

The aim of the work was to study a potential relationship between acrosome response characteristics of bovine spermatozoa and their ability to fertilize oocytes and produce in vitro embryos. Sperm of artificial insemination bulls with a high rate (22.0 ± 4.1%, group A, n = 7) or a low rate (10.3 ± 4.1%, group B, n = 8) of embryos were used. For acrosome assessment, motile spermatozoa from a Percoll gradient were incubated with or without heparin and examined by the fix-vital sperm assay (FVSA). The differences between the heparin-treated (H+) and the non-treated (H−) spermatozoa were significant (p < 0.01) in all bulls at all tested intervals. According to the kinetics of the heparin response, the bulls fell into three categories: fast (FR, n = 7), moderate (MR, n = 5) or slow (SR, n = 3) acrosome responses (p < 0.01). Five MR bulls were found in group A in comparison with two MR bulls in group B (57.1 vs 12.5%; p < 0.05). Intensity of the acrosome response (response index) was significantly higher in bull group A compared with bull group B (7.0 vs 4.6, p < 0.01). A positive correlation was recorded between response index and embryo rate (r = 0.668, p < 0.01). In conclusion (a) the kinetics of spermatozoa response to heparin may be important for in vitro fertilization, bulls with a moderate response appearing to be most suitable for embryo production; (b) greater spermatozoa response to heparin was related to more effective embryo production.
Response of thick and thin film λ/2 microstrip rejection filter to leaf moisture
Authors: Ghorpade Rajesh , Puri Vijaya
Published: March 2006

Thick and thin film λ/2 microstrip L section rejection filters in the X and Ku bands have been used to investigate the effect of leaf moisture on their response. The results reported are in the form of a comparative study of the X and Ku band response of the rejection filters. The investigations are aimed at using the overlay technique for studying the effect of leaf moisture changes on the rejection property of the filter. The leaves investigated were Tradescantia (magenta), Pothas Scandens (green), and Acalypha (bicolored red and green). These leaves were chosen because of their differences in thickness, texture, and color or chlorophyll content. The effects in the Ku band are more dramatic than in the X band for high moisture content (fresh leaves). The results show differences in the response of the thick and thin film filters to condition of leaf overlay. The response to moisture content in the dried leaves is almost similar irrespective of type of metallization of the filter, though the thick film filter seems to be more useful in the X band since some differences between 24 hour dried and 48 hour dried leaf overlay are seen.
Surface creep along the Longitudinal Valley fault, Taiwan from InSAR measurements
Authors: Hsu Leslie , Bürgmann Roland
Published: March 2006

We use interferometric synthetic aperture radar (InSAR) analysis in eastern Taiwan to study reverse creep on the Longitudinal Valley fault (LVF). A stack of the three highest‐quality image pairs spanning 1997–2000 shows sharp range change offsets along the eastern side of the Longitudinal Valley, suggesting 11–35 mm/yr of surface creep between 23 and 23.4°N. No shallow slip was observed along the northern or southern ends of the valley, nor on mapped fault traces on the western edge of the valley. The width of the zone of deformation varied, suggesting distributed shear in shallow sediments above the creeping fault in some places. The InSAR results support the view that although surface creep is rapid in certain locations, significant portions of the LVF are locked and thus represent a substantial seismic hazard.
Interferometric synthetic aperture radar atmospheric correction: Medium Resolution Imaging Spectrometer and Advanced Synthetic Aperture Radar integration
Authors: Li Zhenhong , Fielding Eric J. , Cross Paul , Muller Jan‐Peter
Published: March 2006

Atmospheric water vapor effects represent one of the major limitations of repeat‐pass InSAR, and limit the accuracy of deformation rates derived from InSAR. The use of contemporaneous MERIS data to correct ENVISAT ASAR measurements shows a significant reduction in water vapor effects. After correction, the RMS differences between GPS and InSAR range changes in the satellite line of sight direction decreased to 0.55 cm with a reduction of up to 0.35 cm. It is also shown that it is possible to implement an extra ‘conservative’ cloud mask and obtain better water vapor corrections than that from using the official ESA cloud mask product.
Non‐traditional reflection of internal waves from a sloping bottom, and the likelihood of critical reflection
Authors: Gerkema Theo , Shrira Victor I.
Published: March 2006

The problem of internal inertio‐gravity wave reflection from an arbitrarily orientated uniform slope is solved in a linear setting and with Coriolis effects fully included; that is, the horizontal component () of the Earth rotation vector is taken into account. A new criterion is derived for critical reflection. The presence of creates a specific anisotropy: the criterion depends on the orientation of the bottom slope in the horizontal geographical plane, while it does not depend on the horizontal orientation of the incident wave. Using an empirical‐based bottom‐slope distribution, the probability of critical reflection is calculated for diurnal and semi‐diurnal internal‐tide bands, for a range of latitudes and for various values of stratification. The probability is largest near the inertial latitudes, i.e., when the internal tides are near‐inertial. It is explained how the inclusion of gives significant changes in the probability near these latitudes, especially for weak stratification.
Eastward electrojet in the morning sector
Authors: Rostoker Gordon , Fenrich Frances , Lerner Rob
Published: March 2006

The growth of an eastward electrojet in the afternoon and midnight sector is usually interpreted as the growth of directly driven activity which may terminate in a substorm expansive phase onset. If the eastward electrojet is detected shortly after magnetic midnight, it is thought to be the extension of the evening sector electrojet into the early morning hours. In this paper we shall show that an eastward electrojet can develop at high latitude in the morning sector and that it may be a consequence of the presence of northward electric field poleward of the morning sector westward electrojet at times when the high latitude ionosphere is sunlit.
Carbon dioxide exchange and early old‐field succession
Authors: Emanuel Ryan E. , Albertson John D. , Epstein Howard E. , Williams Christopher A.
Published: March 2006

Old‐field succession is a widespread process active in shaping landscapes in the eastern United States, contributing significantly to the terrestrial sink of atmospheric carbon dioxide, particularly at midlatitudes. However, few studies document ecosystem‐scale carbon dioxide exchange during the early years of old‐field succession, particularly during the temporal transition from cultivation to abandonment. Rates of carbon dioxide exchange were measured for 20 months over a field in Virginia during the transition from an actively cultivated crop field to an unmanaged old field, including one season of crop growth and two seasons of successional growth. Ecosystem carbon respiration exceeded carbon assimilation during growing seasons and dormant periods, resulting in a net flux of carbon dioxide from the biosphere to the atmosphere of between 1.27 and 1.85 kg C m−2 for the entire 20‐month period (an average loss to the atmosphere of 2.07 to 3.01 g C m−2 day −1). Crop growth (from 10 January 2001 to 6 June 2001) resulted in a net loss of between 0.22 and 0.32 kg C m−2 to the atmosphere (an average daily loss of 1.5 to 2.2 g C m−2), whereas the two seasons of successional growth combined contributed an additional 1.05 to 1.53 kg C m−2 to the atmosphere (an average daily loss of 2.2 to 3.3 g C m−2). Empirical modeling was used to demonstrate control of ecosystem carbon respiration by soil temperature, soil moisture status, and the status of vegetation growth activity. Tower‐based estimates of carbon loss were compared at both short (half hourly) and long (seasonal) timescales to independent, ground‐based measurements. Using estimates of carbon exchange from previously published studies, these results are placed in the context of a trajectory of old‐field succession.
El Niño–like pattern in the Pacific during marine isotope stages (MIS) 13 and 11?
Authors: Mohtadi Mahyar , Hebbeln Dierk , Nuñez Ricardo Samuel , Lange Carina B.
Published: March 2006

Paleoceanographic evidence from midlatitudes bearing on the long‐term development of Pacific Ocean surface circulation through the middle and late Pleistocene is scant because of a lack of marine paleorecords exceeding the last four or five glacial cycles. Here we compare benthic and planktonic foraminiferal stable carbon isotope data from a 1‐Myr marine record in the southeastern subtropical Pacific with records from the equatorial Pacific and Southern Ocean in order to reconstruct sea surface circulation in this part of the world ocean and its possible link to the El Niño/Southern Oscillation (ENSO). We especially address marine isotope stages (MIS) 13 and 11, when internal climate dynamics are suggested to produce somewhat unusual interglacial periods. Our results show that the Southern Ocean controlled the circulation in the subtropical Pacific throughout the middle and late Pleistocene and that the hitherto existing hypotheses cannot explain the peak δ13C values in both MIS 13 and 11. We argue that the surface circulation pattern in the southeast Pacific during MIS 13 and 11 should have differed from any other interglacial, and we suggest that the subsequent changes in the latitudinal and meridional heat and moisture transfer contributed to the unusual paleoceanographic settings during these stages. We further hypothesize unusually strong El Niño–like conditions during MIS 13 and 11. This hypothesis, if true, challenges a direct forcing of ENSO by orbital parameters.
Identifying sources of a conservative groundwater contaminant using backward probabilities conditioned on measured concentrations
Authors: Neupauer Roseanna M. , Lin Ranhao
Published: March 2006

If contamination is observed in an aquifer, a backward probability model can be used to obtain information about the former position, source location, or release time of the observed contamination. A backward location probability density function (PDF) describes the possible former positions of an observed contaminant particle at a specified time in the past and can be used to identify the location of the contaminant source. A backward travel time probability density function describes the possible travel times of an observed contaminant particle from a known upgradient location to the observation location and can be used to determine the time of release of contamination from the source. Neupauer and Wilson (1999, 2001, 2002) obtained backward PDFs that depend on the observation locations and sampling times, in addition to the transport properties of the aquifer and solute. We present an approach for conditioning these backward PDFs on measured concentrations. We focus on identifying the location or release time of an instantaneous point source of contamination. We derive the conditioning equations and demonstrate some important features of the technique through the use of a hypothetical example.
Effect of historical changes in land use and climate on the water budget of an urbanizing watershed
Authors: Claessens Luc , Hopkinson Charles , Rastetter Edward , Vallino Joseph
Published: March 2006

We assessed the effects of historical (1931–1998) changes in both land use and climate on the water budget of a rapidly urbanizing watershed, Ipswich River basin (IRB), in northeastern Massachusetts. Water diversions and extremely low flow during summer are major issues in the IRB. Our study centers on a detailed analysis of diversions and a combined empirical/modeling treatment of evapotranspiration (ET) response to changes in climate and land use. A detailed accounting of diversions showed that net diversions increased due to increases in water withdrawals (primarily groundwater pumping) and export of sewage. Net diversions constitute a major component of runoff (20% of streamflow). Using a combination of empirical analysis and physically based modeling, we related an increase in precipitation (2.7 mm/yr) and changes in other climate variables to an increase in ET (1.7 mm/yr). Simulations with a physically based water‐balance model showed that the increase in ET could be attributed entirely to a change in climate, while the effect of land use change was negligible. The land use change effect was different from ET and runoff trends commonly associated with urbanization. We generalized these and other findings to predict future streamflow using climate change scenarios. Our study could serve as a framework for studying suburban watersheds, being the first study of a suburban watershed that addresses long‐term effects of changes in both land use and climate, and accounts for diversions and other unique aspects of suburban hydrology.
Hydrologic and topographic controls on storm‐event exports of dissolved organic carbon (DOC) and nitrate across catchment scales
Authors: Inamdar Shreeram P. , Mitchell Myron J.
Published: March 2006

Patterns of DOC and nitrate (NO3−) concentrations and fluxes were studied for six storm events across four forested, glaciated, subcatchments (1.6 to 696 ha) in western New York, USA. End‐member mixing analysis (EMMA) showed that catchment runoff was composed of shallow groundwater (SGW) discharged at seeps and throughfall (THF) on the rising limb and THF and riparian water (RW) on the recession limb. High THF NO3− contributions produced a pronounced rise and maximum in streamflow NO3−, while low THF concentrations resulted in a dilution trajectory. We did not find any evidence for NO3− flushing by a rising water table. We propose an alternate model for NO3− where the occurrence of seeps and steep slope gradients are the primary determinants of NO3− generation and delivery, and VSAs or saturated areas have a secondary role as loci for interception of NO3− contributions from throughfall. Exports of DOC from the catchments were attributed to THF contributions and the flushing of riparian and hillslope‐bench saturated areas. Concentrations of DOC increased with increasing catchment size and percent‐saturated area whereas NO3− values showed an opposite trend. Concentrations of DOC from a wetland catchment were consistently high, but higher percent increases in event DOC concentration were observed for those catchments with riparian and hillslope‐bench saturated areas. Catchments dominated by riparian zones and catchments with discrete, distal wetlands may have substantial untapped stores of DOC, which become mobilized during high moisture conditions. Thus wetlands in steeply incised valleys may not be effective in buffering hillslope solute loadings.
A stochastic analysis of transient two‐phase flow in heterogeneous porous media
Authors: Chen Mingjie , Keller Arturo A. , Zhang Dongxiao , Lu Zhiming , Zyvoloski George A.
Published: March 2006

The Karhunen‐Loeve moment equation (KLME) approach is implemented to model stochastic transient water‐NAPL two‐phase flow in heterogeneous subsurface media with random soil properties. To describe the constitutive relationships between water saturation, capillary pressure, and phase relative permeability, the widely used van Genuchten model and Parker and Lenhard models are adopted. The log‐transformed intrinsic permeability, soil pore size distribution, and van Genuchten fitting parameter n are treated as normally distributed stochastic variables with a separable exponential covariance model. The perturbation part of these three log‐transformed variables is decomposed via Karhunen‐Loeve expansion. The dependent variables (phase pressure, phase mobility, and capillary pressure) are expanded by polynomial expansions and the perturbation method. Incorporating these expansions of random soil properties variables and dependent variables into the governing equations yields a series of differential equations in different orders. We construct the moments of the dependent variables from the solutions of these differential equations. We demonstrate the stochastic model with two‐dimensional examples of transient two‐phase flow. We also conduct Monte Carlo simulations using the finite element heat and mass (FEHM) transfer code, whose results are considered “true” solutions. The match between the results from FEHM and KLME indicates the validity of the proposed KLME application in transient two‐phase flow. The computational efficiency of the KLME approach over Monte Carlo methods is at least an order of magnitude for transient two‐phase flow problems.
Vadose zone fluid flow estimates calculated from temperature measurements taken in the southern Albuquerque Basin at Tome, New Mexico
Authors: Reiter Marshall
Published: March 2006

Closely spaced temperature measurements taken across the vadose zone at Tome, New Mexico, suggest upward and/or horizontal fluid flow between ∼58 and ∼30 m depth. The temperature‐depth profile is an independent data set that in the present example is best fitted by the exponential expression characterizing vertically upward water flow. In addition, expressions representing horizontal flow and combined horizontal and vertical flow also provide relatively good fits to the temperature data. A unique hydrogeologic environment is present at the Tome site, where a thick clay layer straddles the water table at ∼59 m depth. Neutron and bulk density porosity logs indicate the clay porosity is largely liquid phase water filled. It is suggested that matrix potential and perhaps osmosis are able to drive an uncommonly large vertical fluid flow for southwestern U.S. desert vadose zone sites because the presence of the saturated clay layer straddling the relatively shallow water table provides ideal conditions. The vertical specific discharge estimate is ∼0.09 m yr−1 liquid water. Horizontal flow may also be possible in the clay layer and is estimated as ∼23 m yr−1. Both the vertical and horizontal flow estimates are not untypical for the saturated zone in the Albuquerque Basin.
Computation of methodology-independent ionic solvation free energies from molecular simulations. I. The electrostatic potential in molecular liquids
Authors: Kastenholz M. A. , Hünenberger Philippe H.
Published: March 2006

The computation of ionic solvation free energies from atomistic simulations is a surprisingly difficult problem that has found no satisfactory solution for more than 15years. The reason is that the charging free energies evaluated from such simulations are affected by very large errors. One of these is related to the choice of a specific convention for summing up the contributions of solvent charges to the electrostatic potential in the ionic cavity, namely, on the basis of point charges within entire solvent molecules (M scheme) or on the basis of individual point charges (P scheme). The use of an inappropriate convention may lead to a charge-independent offset in the calculated potential, which depends on the details of the summation scheme, on the quadrupole-moment trace of the solvent molecule, and on the approximate form used to represent electrostatic interactions in the system. However, whether the M or P scheme (if any) represents the appropriate convention is still a matter of on-going debate. The goal of the present article is to settle this long-standing controversy by carefully analyzing (both analytically and numerically) the properties of the electrostatic potential in molecular liquids (and inside cavities within them). Restricting the discussion to real liquids of “spherical” solvent molecules (represented by a classical solvent model with a single van der Waals interaction site), it is concluded that (i) for Coulombic (or straight-cutoff truncated) electrostatic interactions, the M scheme is the appropriate way of calculating the electrostatic potential; (ii) for non-Coulombic interactions deriving from a continuously differentiable function, both M and P schemes generally deliver an incorrect result (for which an analytical correction must be applied); and (iii) finite-temperature effects, including intermolecular orientation correlations and a preferential orientational structure in the neighborhood of a liquid-vacuum interface, must be taken into account. Applications of these results to the computation methodology-independent ionic solvation free energies from molecular simulations will be the scope of a forthcoming article.
Gel to glass transition in simulation of a valence-limited colloidal system
Authors: Zaccarelli E. , Saika-Voivod I. , Buldyrev S. V. , Moreno A. J. , Tartaglia P. , Sciortino F.
Published: March 2006

We numerically study a simple model for thermoreversible colloidal gelation in which particles can form reversible bonds with a predefined maximum number of neighbors. We focus on three and four maximally coordinated particles, since in these two cases the low valency makes it possible to probe, in equilibrium, slow dynamics down to very low temperatures T. By studying a large region of T and packing fraction ϕ we are able to estimate both the location of the liquid-gas phase separation spinodal and the locus of dynamic arrest, where the system is trapped in a disordered nonergodic state. We find that there are two distinct arrest lines for the system: a glass line at high packing fraction, and a gel line at low ϕ and T. The former is rather vertical (ϕ controlled), while the latter is rather horizontal (T controlled) in the ϕ−T plane. Dynamics on approaching the glass line along isotherms exhibit a power-law dependence on ϕ, while dynamics along isochores follow an activated (Arrhenius) dependence. The gel has clearly distinct properties from those of both a repulsive and an attractive glass. A gel to glass crossover occurs in a fairly narrow range in ϕ along low-T isotherms, seen most strikingly in the behavior of the nonergodicity factor. Interestingly, we detect the presence of anomalous dynamics, such as subdiffusive behavior for the mean squared displacement and logarithmic decay for the density correlation functions in the region where the gel dynamics interferes with the glass dynamics.
Quantum study of Eley-Rideal reaction and collision induced desorption of hydrogen atoms on a graphite surface. I. H-chemisorbed case
Authors: Martinazzo Rocco , Tantardini Gian Franco
Published: March 2006

Collision induced (CI) processes involving hydrogen atoms on a graphite surface are studied quantum mechanically within the rigid, flat surface approximation, using a time-dependent wave packet method. The Eley-Rideal (ER) reaction and collision induced desorption (CID) cross sections are obtained with the help of two propagations which use different sets of coordinates, a “product” and a “reagent” set. Several adsorbate-substrate initial states of the target H atom in the chemisorption well are considered, and CI processes are studied over a wide range of projectile energy. Results show that (i) the Eley-Rideal reaction is the major reactive outcome and (ii) CID cross sections do not exceed 4Å2 and present dynamic thresholds for low values of the target vibrational quantum number. ER cross sections show oscillations at high energies which cannot be reproduced by classical and quasiclassical trajectory calculations. They are related to the vibrational excitation of the reaction products, which is a rather steep decreasing function of the collision energy. This behavior causes a selective population of the low-lying vibrational states and allows the quantization of the product molecular states to manifest itself in a collisional observable. A peak structure in the CID cross section is also observed and is assigned to the selective population of metastable states of the transient molecular hydrogen.
Quantum study of Eley-Rideal reaction and collision induced desorption of hydrogen atoms on a graphite surface. II. H-physisorbed case
Authors: Martinazzo Rocco , Tantardini Gian Franco
Published: March 2006

Following previous investigation of collision induced (CI) processes involving hydrogen atoms chemisorbed on graphite [R. Martinazzo and G. F. Tantardini, J. Chem. Phys. 124, 124702 (2006)], the case in which the target hydrogen atom is initially physisorbed on the surface is considered here. Several adsorbate-substrate initial states of the target H atom in the physisorption well are considered, and CI processes are studied for projectile energies up to 1 eV. Results show that (i) Eley-Rideal cross sections at low collision energies may be larger than those found in the H-chemisorbed case but they rapidly decrease as the collision energy increases; (ii) product hydrogen molecules are vibrationally very excited; (iii) collision induced desorption cross sections rapidly increase, reaching saturation values greater than 10Å2; (iv) trapping of the incident atoms is found to be as efficient as the Eley-Rideal reaction at low energies and remains sizable (3–4Å2) at high energies. The latter adsorbate-induced trapping results mainly in formation of metastable hot hydrogen atoms, i.e., atoms with an excess energy channeled in the motion parallel to the surface. These atoms might contribute in explaining hydrogen formation on graphite.
Kirkwood-Buff integrals of aqueous alcohol binary mixtures
Authors: Perera A. , Sokolić F. , Almásy L. , Koga Y.
Published: March 2006

The Kirkwood-Buff integrals of some binary aqueous alcohol mixtures are computed from the available vapor pressure measurements and compared with previous results as well as small angle neutron scattering experiments. The emphasis of the present report is on accuracy of the results that can be achieved by these two different types of measurements. This seems to be needed, mainly in view of the discrepancies between the various published results, as shown herein. It is argued that agreement in peak positions is more important than that in magnitude. In general, very good agreement is obtained by both methods, and sources of disagreements are discussed. The issue of the computer simulations of aqueous systems and the problematics related to correlations, microheterogeneity, and consequently the Kirkwood-Buff integrals are equally discussed herein.
Critical fluctuations of the micellar triethylene glycol monoheptyl ether-water system
Authors: Haller J. , Behrends R. , Kaatze U.
Published: March 2006

Using the equal volume criterion and also the pseudospinodal conception the critical demixing point of the triethylene glycol monoheptyl ether/water system (C7E3∕H2O) has been determined as Ycrit=0.1 and Tcrit=296.46K (Y, mass fraction of surfactant). From density measurements the critical micelle concentration (cmc) followed as Ycmc=0.007 at 288.15K and Ycmc=0.0066 at 298.15K. The (static) shear viscosity ηs and the mutual diffusion coefficient D of the C7E3∕H2O mixture of critical composition have been evaluated to yield their singular and background parts. From a combined treatment of both quantities the relaxation rate Γ of order parameter fluctuations has been derived. Γ follows power law with universal critical exponent and amplitude Γ0=3.1×109s−1. Broadband ultrasonic spectra of C7E3∕H2O mixtures exhibit a noncritical relaxation, reflecting the monomer exchange between micelles and the suspending phase, and a critical term due to concentration fluctuations. The former is subject to a relaxation time distribution that broadens when approaching the critical temperature. The latter can be well represented with the aid of the dynamic scaling model by Bhattacharjee and Ferrell (BF) [Phys. Rev. A. 31, 1788 (1985)]. The half-attenuation frequency in the scaling function of the latter model is noticeably smaller (Ω1∕2BF≈1) than the theoretically predicted value Ω1∕2BF=2.1. This result has been taken as an indication of a coupling between the fluctuations in the local concentration and the kinetics of micelle formation, in correspondence with the idea of a fluctuation controlled monomer exchange [T. Telgmann and U. Kaatze, Langmuir 18, 3068 (2002)].
Infrared diode laser spectroscopy of jet-cooled NiCO, Ni(CO)3(C13O), and Ni(CO)3(CO18)
Authors: Martinez Alonzo , Morse Michael D.
Published: March 2006

Gas phase infrared spectroscopic investigations of the CO vibration of jet-cooled NiCO, Ni(CO)3(C13O), and Ni(CO)3(CO18) are reported. The spectra were obtained using a recently assembled pulsed-discharge slit-jet IR diode laser spectrometer. The rotationally resolved spectrum of NiCO was collected as it was formed in the discharge, while the spectra of Ni(CO)3(C13O) and Ni(CO)3(CO18) were recorded as they were destroyed. For NiCO, band origins of 2010.692 89(34) and 2010.64528(23)cm−1 were measured, along with values of B0=0.151094(7) and 0.149597(6)cm−1 and B1=0.150244(7) and 0.148742(6)cm−1 for Ni58CO and Ni60CO, respectively. The B0 values for these isotopologs were used to determine the two bond lengths in NiCO, giving r0(Ni–C)=1.641(40)Å and r0(C–O)=1.193(53)Å, in agreement with recent microwave measurements. The constants determined for Ni(CO)3(C13O) were υ0=2022.075753(95)cm−1, B″=0.034736(2)cm−1, and B′=0.034688(2)cm−1. For Ni(CO)3(CO18), υ0=2021.93683(18)cm−1, B″=0.033764(4)cm−1, and B′=0.033710(4)cm−1 were obtained. From these rotational constants, bond lengths of r0(Ni–C)=1.839±0.007Å and r0(C–O)=1.121±0.010Å were obtained. These values are discussed in relation to the bond lengths measured by electron and x-ray diffraction methods.
Theoretical study of the effects of F to Cl chemical substitution on the electronic structure and the luminescence properties of Cs2GeF6:Os4+ and Cs2ZrCl6:Os4+ materials
Authors: Pascual José Luis , Barandiarán Zoila , Seijo Luis
Published: March 2006

It has been experimentally determined that Cs2ZrCl6:Os4+ shows luminescence and up-converted luminescence from the highest t2g4 excited level 2A1g(A1g1), whereas Cs2GeF6:Os4+ 2A1g(A1g1) does not luminescence at all. Ab initio quantum chemical calculations on these materials are presented here and show that the variation of the energy gap between the t2g4 and t2g3eg1 manifolds with F to Cl chemical substitution is a key factor to interpret the experimental findings. This energy gap is calculated to be some 1500cm−1 (≃2ν¯a1g) in the fluoride host, whereas it is about 3300cm−1 (≃9ν¯a1g) in the chloride host. The calculated values for the ground state totally symmetric vibrational frequency ν¯a1g are 626cm−1 (Cs2GeF6:Os4+) and 355cm−1 (Cs2ZrCl6:Os4+), in good agreement with the available experimental data. Geometrical structure of (OsX6)2− clusters (X=F,Cl) embedded in Cs2GeF6 and Cs2ZrCl6 lattices is calculated as well. New assignments for some spectral features based in the results of our calculations are proposed.
Ultraviolet-visible-near infrared and mid-Fourier transform infrared spectroscopic studies of intermolecular interaction in cholesteryl oleyl carbonate in mesophases
Authors: Das P. , Sinha R. K. , Basu S.
Published: March 2006

Ultraviolet-visible-near infrared (UV-Vis-NIR) and Fourier transform infrared (FTIR) spectroscopic studies are presented of molecular association between like molecules of cholesteryl oleyl carbonate, each containing suitable π-donor (steroid ring CC) and π-acceptor (C–O single bonds united with a CO bond to give a carbonate group) moieties. Frequency shifts and intensity enhancements of donor and acceptor oscillators appear to be governed by reduced mass, vibronic coupling constants, and a few other parameters such as relative change in force constants, etc. Donor-acceptor complex formation is characterized not only by the appearance of new bands in the mid-FTIR spectrum but also by the emergence of a new, intense electronic band centered at ∼3700cm−1, the so-called charge-transfer band, in the UV-Vis-NIR spectrum. This band is strong in the smectic-A and solid phases, but progressively diminishes when temperature is raised to realize the upper end of the cholesteric phase and eventually the isotropic phase. Also, a new, small electronic band at ∼360nm, only seen in the entire thermal range of the cholesteric phase, is attributed to the Lifshitz-van der Waals interaction between pretransitional smectic-A domains existing in the cholesteric phase. It is argued that mesophases may owe their thermodynamic stability to both Lifshitz-van der Waals and vibronic coupling (or electron-phonon coupling in extended systems such as smectics and solids) interactions.
Relative humidity control for atomic force microscopes
Authors: Stukalov Oleg , Murray Chris A. , Jacina Amy , Dutcher John R.
Published: March 2006

We describe the design and performance of a relative humidity (RH) control chamber for use with atomic force microscopes (AFM) in which the tip is scanned across the stationary sample. The small volume (∼9cm3) chamber encloses the sample, the cantilever holder, and a commercial humidity/temperature sensor. The RH is controlled by passing a controlled ratio of dry and humid nitrogen gas across the sample. This unique design prevents exposure of the scanner assembly to humid gas and maintains all of the functionalities of the AFM system with no measurable degradation of its performance. Using this system, the RH at the sample position can be varied between 5% and 95% and controlled to within ±0.2% during an AFM measurement. To demonstrate the performance of the RH control chamber in imaging and force spectroscopy modes, we have characterized the RH-dependent swelling of small chitosan droplets with diameters of 3–40μm, and the RH dependence of capillary forces between the AFM tip and a mica surface.
Microphotoluminescence of exciton and biexciton around 1.5μm from a single InAs∕InP(001) quantum dot
Authors: Saint-Girons G. , Chauvin N. , Michon A. , Patriarche G. , Beaudoin G. , Brémond G. , Bru-Chevallier C. , Sagnes I.
Published: March 2006

We report on the fabrication by low-pressure metalorganic vapor phase epitaxy of InAs∕InP(001) quantum dots (QDs) emitting around 1.5μm, and on the observation of microphotoluminescence (μPL) from a single QD in this wavelength range. The QDs are diamond shaped, with a density of 6.3∙109cm−2. μPL experiments were carried out on a QD sample covered with a gold mask containing apertures (diameter of 200nm). Well defined peaks corresponding to the emission of single QDs were recorded between 1.24 and 1.6μm. The analysis of the pump power dependence of their intensity allows us to discriminate between exciton and biexciton emission lines.
Laser irradiation and its effects on heat transfer in heat assisted magnetic recording
Authors: Hu Shengbin , Xu Baoxi
Published: March 2006

Heat assisted magnetic recording is proposed to be a candidate to overcome superparamagnet effect and support terabit∕in.2 recording. However, laser heating technique induces serious challenges to build a reliable and stable head-disk interface. One of them is how to measure the temperature in the disk magnetic layer of which thickness is around the nanometer level and in a slider giant magnetoresistive (GMR) sensor. In this article, we propose a novel method to measure temperature in magnetic media and slider of GMR sensor. It combines material characterization by vibration scanning magnetometer and read/write performance characterization of magnetic head and disk on spin stand. Experimental results of temperature rise in the slider and locally heated region in a magnetic disk are presented. Under various laser power irradiations, glass substrate disks with/without magnetic recording layer (on one side) were used. All experiments were performed on Guzik spin stand with an attached optical system. Results indicate that the heat transfers not only from the slider to the air bearing surface but also from the locally heated magnetic disk to the slider through the air bearing. The heat distribution on the slider depends on the slider material and the laser beam location. The results also show that the resistance variation in the GMR sensor could be a good indicator to monitor slider flying height fluctuation in the future.
Neutral particle analyzer diagnostics on the TCV tokamak
Authors: Karpushov Alexander N. , Duval Basil P. , Schlatter Christian , Afanasyev Valery I. , Chernyshev Fedor V.
Published: March 2006

Experimental apparatus and data analysis techniques used in neutral particle analyzer (NPA) diagnostics on the Tokamak à Configuration Variable (TCV) are described. Two NPAs are used on TCV to measure the energy spectrum of neutral particle fluxes from the plasma. The “five-channel energy analyzer of atomic particles” used in double electrical analysis mode with fast voltage sweeping detect particles without atomic mass discrimination in the energy range of 0.6–8.0keV with a time resolution of 0.5–2.0ms and an energy resolution of 7%–20%. The 28-channel “compact neutral particle analyzer” (CNPA) is an EIIB spectrometer with mass and energy separations designed for medium sized fusion machines featuring a carbon neutral stripping foil, a permanent magnet for dispersion, and channel-electron multiplier detectors. The CNPA simultaneously detects two mass species [hydrogen (H) and deuterium (D) or D and helium (He)] in the 0.5–50keV energy range with a resolution of 60%–10% and a time resolution of 0.5–4.0ms. The CNPA views the plasma across the path of the diagnostic neutral beam and can perform active charge-exchange NPA measurement. Data analysis procedures and numerical algorithms developed for NPA measurement are routinely used on TCV to obtain information on the plasma ion temperature, ion energy distribution function, plasma isotope ratios, and other plasma characteristics.
High sensitivity cymbal-based accelerometer
Authors: Sun Cheng-Liang , Lam K. H. , Choy S. H. , Chan H. L. W. , Zhao X.-Z. , Choy C. L.
Published: March 2006

A high sensitivity piezoelectric accelerometer has been developed by replacing the conventional piezoelectric rings with a cymbal transducer. The sensitivity of the cymbal-based accelerometers containing cymbal transducers with different endcap thicknesses and different seismic masses has been measured as a function of driving frequency. Due to the high d33′ coefficient of the cymbal transducers, the cymbal-based accelerometers have a high sensitivity of ∼97pC∕ms−2 with the amplitude rise of 2.85% (<1dB) at one-third of the mounted resonance frequency (3.38kHz). The effect of the seismic mass, the resonance frequency, and d33′ coefficient of the cymbal transducers on the sensitivity and the frequency range of the cymbal-based accelerometers are reported.
On the wide-energy-range tuning of x-ray photoemission electron microscope optics for the observation of the photoelectrons excited by several keV x-rays
Authors: Yasufuku H. , Yoshikawa H. , Kimura M. , Vlaicu A. M. , Kato M. , Kudo M. , Fujikata J. , Fukushima S.
Published: March 2006

We have newly developed an x-ray photoemission electron microscope (XPEEM) which uses both soft x-rays and hard x-rays at the undulator beam line BL15XU in the synchrotron radiation (SR) facility SPring-8 to observe various practical materials. In combination with an energy analyzer and high brilliant x-ray source, the detection of high kinetic energy inner-shell photoelectrons is essential for revealing the chemical properties of specimen subsurfaces or buried interfaces, owing to long inelastic mean free path of the high kinetic energy photoelectrons. The most significant result in our design is the new combined electric and magnetic field objective lens in which the magnetic field penetrates up to the sample surface. This allows the measurement with high spatial resolution of both low intensity images of inner-shell photoelectrons with high kinetic energy and high intensity images of secondary electrons. By using the sample bias scan method, we can easily change the focus condition of the objective lens in order to allow the energy filtered imaging with photoelectrons having the kinetic energy in a wide range (1–10000eV). By the combination of high brilliant SR x-rays, the new objective lens, and sample bias method, our XPEEM can successfully obtain the microarea x-ray photoelectron spectra and energy filtered XPEEM images of inner-shell photoelectrons, such as Si 1s, without any surface cleaning procedure. The energy filtered XPEEM image using photoelectrons from deep inner shells, Si 1s, was obtained for the first time.
Geometrical enhancement of field emission of individual nanotubes studied by in situ transmission electron microscopy
Authors: Xu Zhi , Bai X. D. , Wang E. G.
Published: March 2006

Field emission of an individual multiwalled carbon nanotube, driven by a customer-built piezomanipulator, was measured in a transmission electron microscope. The measurement geometry and the nanotube structure were imaged in situ. A linear dependence of field enhancement factor β on the distance d between the nanotube tip and its counteranode is found. The enhanced field emission mechanism is studied by a tip-flat emission model. The results indicate that the radius of emission apex r is an important factor in field emission with a relationship of β∝r−1∕2, while the tube length has little influence on β.
Viscoelastic properties of polymer surfaces investigated by nanoscale dynamic mechanical analysis
Authors: Chakravartula A. , Komvopoulos K.
Published: March 2006

The viscoelastic properties of polymer surfaces were investigated by nanoscale dynamic mechanical analysis (nano-DMA) involving contact force modulation in the frequency range of 10–200Hz. Nano-DMA experiments were performed with a Berkovich diamond tip of nominal radius of curvature equal to ∼100nm under a mean contact force of 8–10μN and alternating force equal to 2% of the mean force. Variations in the loss tangent, storage modulus, and loss modulus of low- and high-density polyethylene and ultrahigh molecular weight polyethylene with the force frequency demonstrated significantly different viscoelastic behaviors for shallow depths (<40nm) than for relatively large depths (i.e., 75–100nm). The effects of alternating force frequency and indentation depth on the viscoelastic properties of the different polyethylene materials are interpreted in terms of the microstructure characteristics and the molecular chain mobility at the polymer surfaces. The results show that nano-DMA is an effective technique for nanoscale studies of the viscoelastic behavior of polymer surfaces.
Superconducting π qubit with three Josephson junctions
Authors: Yamashita T. , Takahashi S. , Maekawa S.
Published: March 2006

We propose a qubit consisting of a superconducting ring with two zero junctions and one ferromagnetic π junction. In the system, degenerate states appear in the phase space without an external magnetic field because of a competition between the zero and π states. Quantum tunneling between the degenerate states leads to a formation of bonding and antibonding states which are used as a bit. For manipulating the states, only a small magnetic field around zero is required. This feature leads to a large-scale integration and a construction of the smaller-sized qubit which is robust to the decoherence by external noises.