bluuebunny/crossref_metadata_2025_split huggingface dataset:
Construction of Organic Monolayers with Electron Transfer Function on a Hydrogen Terminated Si(111) Surface via Silicon–Carbon Bond and Their Electrochemical Characteristics in Dark and Under Illumination
Authors: Masuda Takuya , Uosaki Kohei 
Published: May 2004

Abstract
An organic monolayer with a functional group of electron mediation capability, viologen, was constructed on a hydrogen-terminated Si(111) surface via Si–C bond by photochemical attachment of 4-vinylbenzyl chloride followed by a surface quarternization reaction with 1-methyl-4-(4-pyridyl)pyridinium iodide. Furthermore, Pt particles were deposited on the monolayer by ion exchange reaction with PtCl42− followed by reduction by hydrogen gas. The mediation of electron transfer by viologen moieties was proved and electrochemical hydrogen evolution reaction rates were enhanced after the Pt deposition.
Synthesis and Adsorption Property of Calixarene-p-sulfonate-intercalated Layered Double Hydroxides
Authors: Sasaki Satoru , Aisawa Sumio , Hirahara Hidetoshi , Sasaki Akira , Narita Eiichi 
Published: May 2004

Abstract
The synthesis of the p-sulfonate[4]calixarene (CS4)/M2+–Al layered double hydroxides (Mg–Al and Zn–Al/CS4/LDHs) has been investigated as well as their adsorption behavior of benzyl alcohol (BA) in aqueous solution. The CS4/LDHs were easily synthesized by the conventional coprecipitation method. The basal spacing of the CS4/LDHs was expanded to 1.33 (Mg–Al) and 1.61 nm (Zn–Al), which indicates that CS4 cavity axis was oriented vertically (Mg–Al) and parallel (Zn–Al) to the LDH basal layer, respectively. In particular, the Zn–Al/CS4/LDH was found to have 2 types of micro pore, the CS4 cavity and the intermolecular space. The adsorption of BA to the CS4/LDH was influenced by the amount and orientation of CS4 ion in the interlayer of the LDHs.
Effect of Additives on Electrochemical Reduction of Oxygen in the Presence of Methanol
Authors: Shiroishi Hidenobu , Ayato Yusuke , Kunimatsu Keiji , Okada Tatsuhiro 
Published: May 2004

Abstract
Methanol oxidation on platinum has been suppressed and selective oxygen reduction was achieved in sulfuric acid – methanol aqueous solution by adding organic ligands or their complexes which have pyridyl structures.
Complementary Multicomplexation of Desymmetrized 2,2′-Bipyridine Ligands on Square Planar Pd(II) Centers
Authors: Tominaga Masahide , Kusukawa Takahiro , Sakamoto Shigeru , Yamaguchi Kentaro , Fujita Makoto 
Published: May 2004

Abstract
Upon complexation with Pd(II) ion, desymmetrized chelating ligand, 6-methyl-2,2′-bipyridine (1), gives only anti Pd·(1)22+ complex. This regioselective complexation is applied to complementary multicomplexation of liner molecular strands: namely, a strand containing two methyl-substituted 2,2′-bipyridine units is selectively complexed on Pd(II) with its counterpart strand in which methyl groups are complementarily substituted.
Guaiacol Oxidation Products in the Enzyme-Activity Assay Reaction by Horseradish Peroxidase Catalysis
Authors: Tonami Hiroyuki , Uyama Hiroshi , Nagahata Ritsuko , Kobayashi Shiro 
Published: May 2004

Abstract
In the horseradish peroxidase (HRP)-catalyzed oxidation of guaiacol (1), trimeric products, and diastereomers of biphenoquinones have been newly identified. The oxidation product was analyzed by HPLC, liquid chromatography electrospray ionization mass spectrometry (LC-ESIMS), and 1H NMR spectroscopy.
Pressure-dependent Activity of Dihydrofolate Reductase from a Deep-sea Bacterium Shewanella violacea Strain DSS12
Authors: Ohmae Eiji , Kubota Kazumasa , Nakasone Kaoru , Kato Chiaki , Gekko Kunihiko 
Published: May 2004

Abstract
A new dihydrofolate reductase (svDHFR) was purified from a deep-sea bacterium, Shewanella violacea strain DSS12, isolated from the Ryukyu Trench (5110 m). In contrast with E. coli DHFR, the enzyme activity of svDHFR increased with increasing hydrostatic pressure up to 100 MPa, suggesting that the enzyme kinetics and structural fluctuation of svDHFR are adapted to a high-pressure environment.
Large‐eddy simulation of turbulent flow in a street canyon
Authors: Cui Zhiqiang , Cai Xiaoming , J. Baker Chris 
Published: June 2004

AbstractThe turbulent flow inside an idealized urban street canyon with an aspect ratio of one is studied by means of large‐eddy simulation. The Regional Atmospheric Modelling System is configured to simulate the turbulent flow in a neutrally stratified atmosphere with the initial wind perpendicular to the street canyon axis. The mean velocity components, resolved‐scale turbulent kinetic energy (RS‐TKE), the skewness and kurtosis of the resolved‐scale velocity components (u along the canyon and w vertically) are compared with wind‐tunnel measurements. The comparison indicates that a reasonable agreement is achieved. The simulation slightly underestimates the intensity of the primary eddy. It is found that distribution of the RS‐TKE is very asymmetric: high in the vicinity of the downstream wall, and uniformly low in the vicinity of the upstream wall. The analyses of skewness and kurtosis indicate that there is a layer just below the rooftop in the canyon where ejection events dominate. Quadrant analysis of resolved‐scale velocity fluctuations, u′ and w′, under the rooftop at the centre of the canyon reveals that the exchange of momentum across the canyon top is contributed unevenly by different events. Weak ejection events dominate the frequency of occurrences, but fewer strong sweep events contribute the majority of the total momentum transfer. The features of momentum transfer are further investigated by analysing the spatial–temporal variations of u′, w′,and u′w′ at the roof level. It is found that the variation of these variables is highly intermittent and is associated with multi‐scale turbulent events. The period of eddies containing high RS‐TKE is attributed to the Kelvin–Helmhotz instabilities. These results improve our understanding of the turbulent structure in street canyon flow. Copyright © 2004 Royal Meteorological Society
Large‐eddy simulation of atmospheric convection on Mars
Authors: Michaels Timothy I. , Rafkin Scot C. R. 
Published: June 2004

AbstractLarge‐eddy simulations are performed using the Mars Regional Atmospheric Modeling System (a nonhydrostatic, mesoscale model) in order to obtain a detailed, three‐dimensional understanding of the daytime Mars atmospheric boundary layer. These microscale runs utilize the full radiative‐transfer (including a static dust profile) routines of the mesoscale model and a multi‐level, prognostic subsurface thermal model. Surface albedo, thermal inertia, Coriolis parameter and solar forcing are homogeneously set to values at the Mars Pathfinder landing site (19.33°N,33.55°W (IAU1991); Ls=143°). The initial state is obtained from a previous mesoscale simulation, and is representative of the Mars Pathfinder landing site during summer.The convective boundary layer of Mars is found to exhibit structures and turbulent statistics outwardly similar to those of earth's convective boundary layer. However, direct infrared radiative heating of the near‐surface atmosphere is the primary mechanism for the transfer of energy from the solar‐heated surface, and affects the behaviour of the convection. Mars convection is more intense than that on earth, primarily due to lesser gravity and atmospheric mass. Also, certain empirical scaling constants within the subgrid‐scale turbulence parametrization (originally developed for terrestrial large‐eddy simulations) appear to require significant reduction in order for the scheme to perform adequately on Mars. The simulation results are used to further meaningfully interpret spacecraft images of convective clouds. The results also compare favourably with Mars Pathfinder in situ meteorological measurements, and help reconcile large daytime variances in that dataset. Copyright © 2004 Royal Meteorological Society
A simulation study of 1D variational cloud retrieval with infrared satellite data from multiple fields of view
Authors: Szyndel M. D. E. , Collard A. D. , Eyre J. R. 
Published: June 2004

AbstractA method for retrieving cloud‐top height using one‐dimensional variational analysis with multiple pixels is examined. The method is tested for a range of cloud scenarios using simulated multi‐spectral infrared imagery. The skill of the multiple pixel method is compared to the skill of the single‐field‐of‐view method. It is found that, when applied to two pixels, the multiple‐field‐of‐view method considerably increases the skill of retrieval for the less cloudy pixel, and marginally improves the skill of retrieval for the cloudier pixel in the majority of cases. It is also found that, when applied to six pixels, the multiple‐field‐of‐view method has a positive impact in many cases. © Crown copyright, 2004. Royal Meteorological Society
Evolution and dynamics of summertime blocking over the Far East and the associated surface Okhotsk high
Authors: Nakamura Hisashi , Fukamachi Tomohiro 
Published: June 2004

AbstractTime evolution and dynamics of an upper‐level blocking ridge over the Far East and the associated surface high over the Sea of Okhotsk that give rise to abnormal summertime coolness over eastern Japan are investigated through a composite analysis applied to distinct surface high events. The formation mechanism and vertical structure of the blocking differ fundamentally between May and July, attributable to seasonal changes in the jet structure, storm‐track activity over the Far East and the land–sea thermal contrast within the Okhotsk region. In May, forcing from migratory eddies is strong enough for precursory anticyclonic anomalies retrograding slowly over the North Pacific to develop into a blocking ridge. The ridge remains equivalent barotropic under the weak land–sea thermal contrast in the Okhotsk region. In contrast, the eddy forcing is no longer the primary factor for the blocking formation in July, in the presence of the weakened and split westerlies. Rather, the propagation of a stationary Rossby wave packet that has emanated from precursory anticyclonic anomalies over northern Europe stagnates over the Far East, and the subsequent local breaking of the packet leads to the blocking formation. In a particular case in July 1993, a wave packet involved in blocking formation could be traced back as far upstream as the east coast of North America over the two previous weeks. Acting on the strong thermal contrast in July between the cool sea surface and a warm land mass to the west, the anomalous surface easterlies induced by the blocking ridge can build up a cold surface anticyclone through cold advection, rendering the blocking anomalies distinctly baroclinic. Copyright © 2004 Royal Meteorological Society
The role of the south‐east Asian monsoon and other seasonal features in creating the ‘tape‐recorder’ signal in the Unified Model
Authors: Bannister R. N. , O'neill A. , Gregory A. R. , Nissen K. M. 
Published: June 2004

AbstractA multi‐year simulation with an atmospheric general‐circulation model (AGCM), the Unified Model, is shown to simulate the main features of seasonal variations in the concentrations of water vapour in the stratosphere—the so‐called tape‐recorder signal. An off‐line transport model, utilizing winds from the AGCM, is used to synthesize the signal from local contributions. During June–July–August, the most significant localized contribution to the moist phase of the signal comes from an air stream emanating from the South‐East Asian monsoon. The moist air does not enter the stratosphere immediately above the monsoon in a localized ‘fountain’. Rather, the air stream moves southward, via the monsoon's upper level anticyclone, into the tropical stratosphere while moving steadily upwards across isentropic surfaces in a field of radiative heating in the tropical tropopause layer (TTL). As a result of this steady ascent during equatorward movement, not all the airstream is freeze dried in the cold cap of low temperatures which exists in the TTL above the monsoon. The water vapour mixing ratios of air entering the stratospheric tape‐recorder are therefore not entirely set by the minimum temperatures near the equator, but in part by physical conditions outside the inner tropical region used to define the tape‐recorder signal. During December–January–February, the flow near the tropopause is simpler. Dry air enters the stratosphere by slow upglide through the localized temperature minimum near the tropical tropopause over the western Pacific. The mixing ratios during the dry phase are set largely by freeze drying in this region. The simple tape‐recorder model, which envisages that mixing ratios are set by the minimum temperature near the tropical tropopause is therefore an oversimplification. Copyright © 2004 Royal Meteorological Society
Observations and simulations of the 8 November 1999 MAP mountain wave case
Authors: Smith S. A. 
Published: June 2004

AbstractA joint aircraft sortie took place over the Swiss Alps as part of the Mesoscale Alpine Program (MAP) on 8 November 1999. The synoptic situation is documented here and the Met Office Unified Model is shown to be capable of producing accurate simulations of the large‐scale flow over and around the Alps by a comparison of model profiles with data from the many radiosonde ascents available on this day. Upstream flow splitting, a cold pool over the Po valley and lee‐side föhn flow are all present in the simulation, and the upstream Scorer parameter and Froude numbers are predicted accurately. Trapped lee waves and vertically propagating waves are predicted at the correct wavelengths. However, the wave amplitudes are underpredicted. This is particularly true at higher levels, where the limited model resolution means that the inversion at the tropopause and its instabilities are not captured. The problems inherent in interpreting aircraft observations along a single transect which is not oriented along the wave vector are highlighted in this study, and an accurate high‐resolution simulation is essential to understanding the otherwise misleading aircraft data. © Crown copyright, 2004. Royal Meteorological Society
A laboratory study of the influence of ice crystal growth conditions on subsequent charge transfer in thunderstorm electrification
Authors: Saunders C. P. R. , Bax‐Norman H. , Avila E.E. , E. Castellano N. 
Published: June 2004

AbstractLaboratory studies of a thunderstorm charging mechanism involving rebounding collisions between ice crystals and riming graupel pellets, have shown the importance of the growth conditions of the interacting ice particles on the sign of the charge transferred. The present study shows a new result: if an ice crystal is not in thermal equilibrium with the environment (immediately following the mixing of two clouds at different saturations) the crystal surface may experience an enhanced growth rate that can influence the sign of the charge transfer and promote negative rimer charging. Furthermore, when an ice crystal in ice saturation conditions is introduced to a cloud at water saturation, leading to transient growth and heating, the period of thermal non‐equilibrium is shown to be sufficiently brief that the enhanced negative rimer charging is short lived. These results suggest that the earlier conclusions of Berdeklis and List—that the cloud saturation conditions around a growing ice crystal impart to the crystal surface a property that is carried with it and that influences the sign of subsequent charge transfer—are unfounded. The discrepancy is because in their laboratory simulations of thunderstorm conditions there is adequate time for the growing ice crystal surface to come to equilibrium with its environment. The established concept of the relative diffusional growth rate of the interacting surfaces controlling the sign of charge transfer, such that the faster growing surface charges positively, is consistent with the observations. Copyright © 2004 Royal Meteorological Society
Structure, genesis and scale selection of the tropical quasi‐biweekly mode
Authors: Chatterjee Piyali , Goswami B. N. 
Published: June 2004

AbstractThe quasi‐biweekly mode (QBM) and the 30–60 day mode are two major intraseasonal oscillations (ISOs) in the tropics. The QBM is known to have a major influence in determining the active and break conditions of the Indian monsoon during the northern summer. A westward‐propagating equatorial Rossby wave with quasi‐biweekly period influences the Australian monsoon during the northern winter. Universality between the summer and winter QBM is established through analysis of daily circulation and convection data for 10 years. It is shown that the mean spatial structure of the QBM in circulation and convection resembles that of a gravest meridional mode equatorial Rossby wave with wavelength of about 6000 km and westward phase speed of approximately 4.5 m s−1. However, the maximum zonal wind occurs at around 5°N (5°S) during the northern summer (winter). The wave structure appears to be translated northward (southward) by about 5° during the northern summer (winter). The relationship between outgoing long‐wave radiation and circulation data indicates that the mode is driven unstable by coupling with moist convection. Similarity in temporal and spatial characteristics of the mode during the two seasons leads us to propose that the same mechanism governs the genesis and scale selection of the mode in both the seasons.An acceptable mechanism for genesis and scale selection of the QBM has been lacking. In the present study, a mechanism for genesis and scale selection of the observed QBM is proposed. A simple 2½‐layer model that includes a steady Ekman boundary layer (BL) formulation incorporating effect of entrainment mixing is constructed for the convectively coupled equatorial waves. Without influence of the background mean flow, moist feedback in the presence of frictional BL convergence drives the gravest meridional mode equatorial Rossby wave unstable with observed wavelength and period but with zonal winds symmetric about the equator. Potential temperature perturbation associated with the Rossby wave is in phase with relative vorticity perturbation at low level. The BL drives moisture convergence in phase with the relative vorticity at the top of the BL. Release of latent heat associated with the BL convergence enhances the potential temperature leading to a positive feedback. The mean flow over the Indian Ocean and western Pacific at low levels is such that the zero ambient absolute vorticity or the ‘dynamic equator’ shifts to around 5°N (5°S) during summer (winter) and results in a shift of the unstable Rossby waves towards the north (south) by about 5°. The resulting structure of the unstable Rossby mode resembles the observed structure of the biweekly mode. It is shown that neither evaporation–wind feedback nor vertical shear of the mean flow is crucial for the existence of the mode. However these processes marginally modify the growth rate and make the structure of the unstable wave more realistic. Copyright © 2004 Royal Meteorological Society
Short‐wave radiative effects of biomass burning aerosol during SAFARI2000
Authors: Osborne Simon R. , Haywood James M. , Francis Peter N. , Dubovik Oleg 
Published: June 2004

AbstractWe present data from two case‐studies during the Southern AFricAn Research Initiative (SAFARI2000) of the radiative effects of a biomass burning plume advecting over the ocean. In situ aircraft measurements were made of the aerosol vertical structure, the aerosol microphysics, and the aerosol optical properties (scattering and absorption coefficients). Remote sensing measurements of the upwelling broadband short‐wave (SW) radiative fluxes (0.3–3.0µm) were made above the plume. Together with modelling of the clear‐air flux using a flexible radiation scheme, we have been able to determine the local mean direct radiative effects of the aerosol column for the two cases. Aerosol optical depths were derived using a number of techniques: the upwelling fluxes, vertical integration of the in situ extinction coefficient, and using downwelling sky radiances. These optical depths are compared and discussed; discrepancies are revealed through instrument sampling problems and horizontal inhomogeneity of the aerosol. Spectrally resolved downwelling SW sky radiances as a function of scattering angle were measured and modelled. The modelling technique illustrates the importance of including unpolluted marine boundary‐layer aerosol as part of the aerosol column. A retrieval algorithm that uses the measured downwelling sky radiances as input has also been utilized. This algorithm derives a columnar aerosol size distribution for comparison against the measured biomass burning and marine boundary‐layer size distributions. The retrieved columnar size distribution is acceptable in representing the atmospheric aerosol in terms of describing the effect on scattered radiances. © Crown copyright, 2004. Royal Meteorological Society
Simulation of the diurnal cycle in a climate model and its evaluation using data from Meteosat 7
Authors: Slingo A. , Hodges K. I. , Robinson G. J. 
Published: June 2004

AbstractThe representation of the diurnal cycle in the Hadley Centre climate model is evaluated using simulations of the infrared radiances observed by Meteosat 7. In both the window and water vapour channels, the standard version of the model with 19 levels produces a good simulation of the geographical distributions of the mean radiances and of the amplitude of the diurnal cycle. Increasing the vertical resolution to 30 levels leads to further improvements in the mean fields. The timing of the maximum and minimum radiances reveals significant model errors, however, which are sensitive to the frequency with which the radiation scheme is called. In most regions, these errors are consistent with well documented errors in the timing of convective precipitation, which peaks before noon in the model, in contrast to the observed peak in the late afternoon or evening. When the radiation scheme is called every model time step (half an hour), as opposed to every three hours in the standard version, the timing of the minimum radiance is improved for convective regions over central Africa, due to the creation of upper‐level layer‐cloud by detrainment from the convection scheme, which persists well after the convection itself has dissipated. However, this produces a decoupling between the timing of the diurnal cycles of precipitation and window channel radiance. The possibility is raised that a similar decoupling may occur in reality and the implications of this for the retrieval of the diurnal cycle of precipitation from infrared radiances are discussed. Copyright © 2004 Royal Meteorological Society