bluuebunny/crossref_metadata_2025_split huggingface dataset:
In vitro assessment of mutagenicity and clastogenicity of BDE‐99, a pentabrominated diphenyl ether flame retardant
Authors: Evandri Maria G. , Mastrangelo Sabina , Costa Lucio G. , Bolle Paola 
Published: August 2003

AbstractPolybrominated diphenyl ethers (PBDEs), which are widely used as flame retardants, are considered persistent organic pollutants. To date, the available toxicological data on PBDEs are limited and were primarily obtained by studying technical blends. The present study was undertaken to investigate the genotoxicity of the pure congener 2,2′,4,4′,5‐brominated diphenyl ether (BDE‐99), one of the major isomers present in penta‐commercial products. Bacterial reverse mutation assays in Salmonella typhimurium strains TA98 and TA100 and in Escherichia coli WP2 uvrA, and the Allium cepa chromosome aberration test were carried out to evaluate mutagenicity and clastogenicity. The experimental design also involved testing a well‐known polychlorinated biphenyl (PCB) mixture, Aroclor® 1254, which is structurally related to PBDEs. BDE‐99 was negative in the bacterial mutagenicity assays, with and without S9 mix. Also, the frequency of structural chromosome aberrations was not significantly higher than the control and no signs of cytotoxicity were observed in BDE‐99‐treated A. cepa. Aroclor® 1254 was not mutagenic, but it induced a significant increase in chromosomal aberrations in A. cepa. In conclusion, BDE‐99 was not mutagenic in S. typhimurium or E. coli, or clastogenic in A. cepa; however, the possibility that PBDEs might act through an epigenetic mechanism cannot be excluded. Environ. Mol. Mutagen. 42:85–90, 2003. © 2003 Wiley‐Liss, Inc.
Mutation frequency analysis of mononucleotide and dinucleotide repeats after oxidative stress
Authors: Yamada Nazumi A. , Parker Jennifer M. , Farber Rosann A. 
Published: August 2003

AbstractMany tumors exhibit genetic instability at the DNA sequence level in the form of frameshift mutations in simple repeats (microsatellite instability). A high level of microsatellite instability, such as that seen in hereditary nonpolyposis colorectal cancer (HNPCC), arises from defects in the mismatch repair pathway. A low level of microsatellite instability is found in some non‐HNPCC‐associated cancers, such as those of the breast and lung, and is not attributable to mismatch repair defects. We hypothesized that oxidative DNA damage may be at least partly responsible for the generation of microsatellite mutations in these tumors. We investigated whether oxidative DNA damage can induce microsatellite mutations in mismatch repair‐proficient cultured cells. Telomerase‐immortalized normal human fibroblasts were stably transfected with a plasmid containing a tk‐neo fusion gene, such that the neo coding region was placed out of frame by the presence of an upstream microsatellite sequence. Cells were treated with H2O2 and mutation frequencies were determined for G17, A17, and (CA)17 repeats. Mutation frequencies of mononucleotide repeats in cells with the neo gene in the (+1) reading frame were reduced after treatment. No effect was observed in cells with the mononucleotide repeats in the (–1) reading frame. A small increase in mutation frequency was observed in cells with the (CA)17 repeat. Our data suggest that diploid human cells may have protective mechanisms that prevent the induction of microsatellite mutations by a short exposure to high levels of oxidative stress. Environ. Mol. Mutagen. 42:75–84, 2003. © 2003 Wiley‐Liss, Inc.
A model of sensitivity: 1,3‐butadiene increases mutant frequencies and genomic damage in mice lacking a functional microsomal epoxide hydrolase gene
Authors: Wickliffe Jeffrey K. , Ammenheuser Marinel M. , Salazar James J. , Abdel‐Rahman Sherif Z. , Hastings‐Smith Darlene A. , Postlethwait Edward M. , Lloyd R. Stephen , Ward Jonathan B. 
Published: August 2003

AbstractThe specific role that polymorphisms in xenobiotic metabolizing enzymes play in modulating sensitivity to 1,3‐butadiene (BD) genotoxicity has been relatively unexplored. The enzyme microsomal epoxide hydrolase (mEH) is important in detoxifying the mutagenic epoxides of BD (butadiene monoepoxide [BDO], butadiene diepoxide [BDO2]). Polymorphisms in the human mEH gene appear to affect the function of the enzyme. We exposed mice with normal mEH activity (WT) and knockout mice without mEH activity (KO) to 20 ppm BD (inhalation) or 30 mg/kg BDO2 (intraperitoneal [IP] injection). We then compared Hprt mutant frequencies (MFs) among these groups. KO mice exposed to BD exhibited a significant (P < 0.05) 12.4‐fold increase in MF over controls and a significant 5.4‐fold increase in MF over exposed WT mice. Additionally, KO mice exposed to BDO2 exhibited a significant 4.5‐fold increase in MF over controls and a significant 1.7‐fold increase in MF over exposed WT mice. We also compared genomic damage in WT and KO mice (comet tail moment) following IP exposure to 3 mg/kg and 30 mg/kg BDO2. KO mice exposed to 3 mg/kg exhibited significantly more DNA damage than controls (7.5–12.1‐fold increase) and exposed WT mice (3 mg/kg; 4.8‐fold increase). KO mice exposed to 30 mg/kg BDO2 exhibited significantly more DNA damage than all other groups (2.3–27.9‐fold increase). Correlation analysis indicated that a significant, positive relationship (r2 = 0.92) exists between comet‐measured damage and Hprt MFs. The lack of mEH activity increases the genetic sensitivity of mice exposed to BD and BDO2. This model should facilitate a mechanistic understanding of the observed variation in human genetic sensitivity following exposure to BD. Environ. Mol. Mutagen. 42:106–110, 2003. © 2003 Wiley‐Liss, Inc.
Frameshift mutations induced by three classes of acridines in the lacZ reversion assay in Escherichia coli: Potency of responses and relationship to slipped mispairing models
Authors: Hoffmann George R. , Calciano Margaret A. , Lawless Bryan M. , Mahoney Kathleen M. 
Published: August 2003

AbstractThe frameshift mutagenicity of 9‐aminoacridine (9AA) was compared with that of quinacrine, the acridine mustards ICR‐191 and quinacrine mustard (QM), and the nitroacridine Entozon in the lacZ reversion assay in Escherichia coli. As intercalating agents, 9AA and quinacrine cause mutations through noncovalent associations with DNA. Mustards and nitroacridines form covalent adducts in DNA and give rise to different spectra of mutations. Quinacrine and 9AA most effectively induced −1 frameshifts in a run of guanine residues, with 9AA being the more potent mutagen. They also induced +G frameshifts. The acridine mustard ICR‐191 was a stronger mutagen than 9AA, owing largely to its potent induction of +G frameshifts. QM induced +G frameshifts more strongly than did its nonreactive counterpart quinacrine. The nitroacridine Entozon differed from the other acridines in being a potent inducer of −2 frameshifts, but it was less effective in inducing ±1 frameshifts. Quinacrine, although a simple intercalator, induced all five kinds of frameshift mutations detected in the assay, as did the acridine mustards. Although +A and −A frameshifts were induced, adenine runs were less susceptible to acridine mutagenesis than guanine runs. The patterns of frameshift mutagenicity in the lacZ assay are similar to those in an assay based on the reversion of mutations in the tetracycline‐resistance gene of the plasmid pBR322. The similarity suggests that the responses reflect the inherent bacterial mutagenicity of the compounds in the local sequence context and are not highly dependent on the broader sequence context. The results are interpreted with respect to slipped mispairing models of frameshift mutagenesis. Environ. Mol. Mutagen. 42:111–121, 2003. © 2003 Wiley‐Liss, Inc.
A twenty‐one‐year record of surface change on a Namib linear dune
Authors: Livingstone Ian 
Published: August 2003

AbstractRepeated surveying of two sites on a Namib linear dune between 1980 and 2001 provides a 21‐year record of dune surface change. The surveys conﬁrm the view that the dunes are not inactive relics but are responding to the present‐day wind regime. They also provide no evidence that the dunes are migrating laterally. Examination of wind data for the survey period provides some evidence that the form of the crest of the dunes is actively responding to the natural year‐by‐year climate variability, such that an increase in the frequency of easterly winds leads to the development of a double‐crested form while fewer easterly winds lead to a single‐crested form. Copyright © 2003 John Wiley & Sons, Ltd.
A simple low‐cost sand catcher for wind‐tunnel simulations
Authors: Cornelis Wim M. , Gabriels Donald 
Published: August 2003

AbstractA simple low‐cost sand catcher has been developed for use in wind‐tunnel experiments. It is 500 mm high with a 300 mm by 20 mm inlet opening, and is designed to measure total mass transport directly. The length is 280 mm and its walls slowly expand at an angle of 5·6°. The top view is similar to that of the widely used BSNE sampler. Each sidewall is vented with three ventilation screens. Two sets of experiments were conducted on dune sand and at different wind velocities to investigate to what degree the catcher samples isokinetically, efﬁciently and non‐selectively. The results indicate that the catcher measures sufﬁciently isokinetically (inlet wind velocity over outside wind velocity >0·9). Catch efﬁciency was around 0·75 and the degree of non‐selectivity was >0·80 for 95 per cent of the particle sizes of the test material. It was also observed that the inﬂuence of wind velocity on the tested sampler characteristics was of minor importance so that no speciﬁc corrections need to be made for different wind velocities. Copyright © 2003 John Wiley & Sons, Ltd.
Particle path length distributions in meandering gravel‐bed streams: results from physical models
Authors: Pyrce Richard S. , Ashmore Peter E. 
Published: August 2003

AbstractIn gravel‐bed rivers with well‐deﬁned pool–bar morphology, the path length of transported bed particles must be, at least during ‘channel‐forming’ ﬂows, equal to the length scale of the morphology. This is the basis for some methods for estimating bed material transport rates. However, previous data, especially from ﬁeld tests, are often strongly positively skewed with mean much shorter than the pool–bar spacing. One possible explanation is that positively skewed distributions occur only in channels lacking distinct pool–bar topography or only at lower discharges in pool–bar channels. A series of ﬂume experiments using ﬂuorescent tracers was used to measure path length distributions in low‐sinuosity meandering channels to assess the relation with channel morphology and ﬂow conditions. At channel‐forming ﬂows, 55 to 75 per cent of the tracer grains were deposited on the ﬁrst point bar downstream of the point of tracer input, with 15 per cent passing beyond the ﬁrst bar. Path length distributions are symmetrical with mean equal to the pool–bar spacing and can be described with a Cauchy distribution. In some cases there was a secondary mode close to the point of tracer introduction; this bimodal distribution ﬁts a combined gamma–Cauchy distribution. Only when discharge was reduced below the channel‐forming ﬂow were frequency distributions unimodal and positively skewed with no relation to the pool–bar spacing. Thus, path length distributions become more symmetrical, and mean path length increases to coincide with pool–bar spacing, as ﬂow approaches channel‐forming conditions. This is a substantial modiﬁcation of existing models of particle transfer in gravel‐bed rivers. Copyright © 2003 John Wiley & Sons, Ltd.
Short‐term erosion rates from a 7Be inventory balance
Authors: Wilson Christopher G. , Matisoff Gerald , Whiting Peter J. 
Published: August 2003

AbstractDetailed soil erosion studies beneﬁt from the ability to quantify the magnitude of erosion over time scales appropriate to the process. An inventory balance for 7Be was used to calculate sediment erosion in a 30·73 m2 plot during a series of runoff‐producing thunderstorms occurring over three days at the Deep Loess Research Station in Treynor, Iowa, USA. The inventory balance included determination of the pre‐ and post‐storm 7Be inventories in the soil, the atmospheric inﬂux of 7Be during the event, and proﬁles of the 7Be activity in the soil following the atmospheric deposition. The erosion calculated in the plot using the 7Be inventory balance was 0·058 g cm−2, which is 23 per cent of the annual average erosion determined using 137Cs inventories. The calculated erosion from the mass balance is similar to the 0·059 g cm−2 of erosion estimated from the amount of sediment collected at the outlet of the 6 ha ﬁeld during the study period and the delivery ratio (0·64). The inventory balance of 7Be provides a new means for evaluating soil erosion over the time period most relevant to quantifying the prediction of erosion from runoff. Copyright © 2003 John Wiley & Sons, Ltd.
The precision of sampling grain‐size percentiles using the Wolman method
Authors: Green Julian C. 
Published: August 2003

AbstractThe precision of sampling different grain‐size percentiles in comparison to each other is of signiﬁcance for choosing which percentile is appropriate to characterize riverbed surface sediments. The traditional view, based on normal grain‐size distributions derived by the Wolman grid‐by‐number method, has identiﬁed the median percentile as having the highest sampling precision. However, grain‐size distributions are highly variable and often fail to follow a theoretical distribution. This paper presents both theoretical and empirical techniques to determine the precision of sampling different percentiles. These methods are then applied to a range of natural distributions found in UK rivers. It is found that grains between the 66th and 91st percentiles are the most precisely sampled, with maximum precision obtained with the 73rd percentile. Copyright © 2003 John Wiley & Sons, Ltd.
Processes, spatio‐temporal factors and measurements of current erosion in the French Southern Alps: a review
Authors: Descroix Luc , Mathys Nicolle 
Published: August 2003

AbstractPresent erosion in mountainous areas of Western Europe causes land management problems, particularly for areas located downstream of erosion zones. Except for transalpine roads and ski resorts, economic activities no longer require as much space as they did in the past. Therefore, natural reforestation has provided signiﬁcant protection for alpine hillslopes during the 20th century. However, extreme ﬂoods continue to cause severe damage in intra‐alpine valleys, as well as in piedmont and surrounding plains, making the study of present water erosion phenomena very important.Many studies have investigated the processes and factors of water erosion on slopes at both the catchment and plot scales. They have focused on rock fragmentation and transportation in different ﬁelds, the spatial and temporal explanatory variables, the consequences downstream (ﬂooding, sedimentation, river bed evolution) and the impact of ﬂoods.In the French Alps, present erosion has been studied in a variety of outcrops, with several recent studies conducted in ﬁelds such as marls, clayey deposits, molasses and moraines. These kinds of outcrops are found throughout the alpine massif, including an area of special interest on the great Jurassic black marl outcrop where badlands are frequently observable. Geomorphologists and hydrologists have been particularly interested in the strong erosion processes in marls, seeking to determine the main patterns and the impact of spatial and temporal factors on soil loss quantities.The main climatic factors of rock disaggregation were found to be the freeze–thaw and wet–dry cycles, which destroy rock cohesion, and the splash effect of rain. The principal site variables are vegetation cover, exposure and dip–slope angle. Erosion rates are two or three orders of magnitude higher on bare soils than on pastures; northern aspect slopes suffer two to four times as much soil loss as southern aspect slopes. Finally, the angle formed by the slope and the dip also determines different behaviours: erosion rates are higher when slope and dip are perpendicular than when they are parallel. The transportation agents are mostly debris ﬂows and runoff caused by intense precipitation. Annual erosion depth in the marls is generally assumed to be substantial, up to 10 mm. The high value can be explained by the severity of the climatic conditions and the brittleness of the lithology, which results in numerous fractures. Copyright © 2003 John Wiley & Sons, Ltd.
Mid‐Holocene sub‐blanket‐peat alluvia and sediment sources in the upper Liffey valley, Co. Wicklow, Ireland
Authors: Thorp Martin , Glanville Peter 
Published: August 2003

AbstractA recently exposed section across a ﬁrst‐order valley buried beneath the regional blanket peat on hillside slopes in the upper Liffey valley, Co. Wicklow, is described. The section shows two alluvia within a shallow valley form underlain by an extensive boulder and stone line over regional till and weathered granite. 14C dates from wood in the alluvia indicate the older alluvium to have formed between 4324 ± 53 BP and 4126 ± 45 BP and the younger between 3217 ± 53 BP and 2975 ± 53 BP. The basal layer of the overlying peat yielded a date of 2208 ± 61 BP. The younger alluvium shows the effects of soil paludiﬁcation prior to the peat expansion. Dated pollen analyses elsewhere in the upper catchment conﬁrm the spread of blanket peat over most areas above 350 m after 4000–3600 BP. The buried valley was contributing sediments to the mid‐Holocene ﬂoodplains in the upper Liffey valley prior to the extension of blanket peat over the catchment after which sediment yields from it and the other catchment slopes declined. Copyright © 2003 John Wiley & Sons, Ltd.
A vertically moving grid finite‐element modelling of tidal flow in the Changjiang Estuary, China
Authors: Shi Z. , Li S. S. , Petersen O. S. 
Published: August 2003

AbstractAn estuarine two‐dimensional vertical finite‐element model of tidal flow has been established by laterally integrating Navier–Stokes equation. To this end, a moving grid finite‐element method has been used. An arbitrarily shaped quadrilateral element has been selected. This model has been validated by using field data from two monitoring stations at the North Passage of the Changjiang Estuary. Using this numerical model, two types of modelled results were obtained: (1) vertical distributions of tidal current velocities at the North Passage of the Changjiang Estuary; (2) longitudinal distributions of tidal current velocities at maximum flood tide, at high slack water, at maximum ebb tide and at low slack water tide at the North Passage of the Changjiang Estuary. The conclusion is that the model provides a reasonable agreement with observed data. Copyright © 2003 John Wiley & Sons, Ltd.
Coupled lubrication and Stokes flow finite elements
Authors: Stay Matthew S. , Barocas Victor. H. 
Published: August 2003

AbstractA method is developed for performing a local reduction of the governing physics for fluid problems with domains that contain a combination of narrow and non‐narrow regions, and the computational accuracy and performance of the method are measured. In the narrow regions of the domain, where the fluid is assumed to have no inertia and the domain height and curvature are assumed small, lubrication, or Reynolds, theory is used locally to reduce the two‐dimensional Navier–Stokes equations to the one‐dimensional Reynolds equation while retaining a high degree of accuracy in the overall solution. The Reynolds equation is coupled to the governing momentum and mass equations of the non‐narrow region with boundary conditions on the mass and momentum flux. The localized reduction technique, termed ‘stitching,’ is demonstrated on Stokes flow for various geometries of the hydrodynamic journal bearing—a non‐trivial test problem for which a known analytical solution is available. The computational advantage of the coupled Stokes–Reynolds method is illustrated on an industrially applicable fully‐flooded deformable‐roll coating example. The examples in this paper are limited to two‐dimensional Stokes flow, but extension to three‐dimensional and Navier–Stokes flow is possible. Copyright © 2003 John Wiley & Sons, Ltd.
A fully implicit method for steady and unsteady viscous flow simulations
Authors: Li Jie , Li Fengwei , E Qin 
Published: August 2003

AbstractIn this paper a time‐accurate, fully implicit method has been applied to solve a variety of steady and unsteady viscous flow problems. It uses a finite volume cell‐centred formulation on structured grids and employs central space discretization with artificial dissipation for the residual computation. In order to obtain a second‐order time‐accurate implicit scheme, a Newton‐like subiteration is performed in the original LU‐SGS method to converge the calculations at each physical time step by means of a dual‐time approach proposed by Jameson. The numerical experiments show that the present method is very efficient, reliable, and robust for steady and unsteady viscous flow simulations, especially for some low speed flow problems. Copyright © 2003 John Wiley & Sons, Ltd.
Numerical analysis of supersonic combustion ramjet with upstream fuel injection
Authors: Savino Raffaele , Pezzella Giuseppe 
Published: August 2003

AbstractThis paper describes possible fuel injection scheme for airbreathing engines that use hydrocarbon fuels. The basic idea is to inject fuel at the spike tip of the supersonic inlet to achieve mixing and combustion efficiency with a limited length combustion chamber. A numerical code, able to solve the full Navier–Stokes equations in turbulent and reacting flows, is employed to obtain numerical simulations of the thermo‐fluidynamic fields at different scramjet flight conditions, at Mach numbers of M=6.5 and 8. The feasibility of the idea of the upstream injection is checked for a simple axisymmetric configuration and relatively small size. The results are discussed in connection with the potential benefits deriving from the use of new ultra high temperature ceramics (UHTC). Copyright © 2003 John Wiley & Sons, Ltd.
Lattice Boltzmann simulations for flow and heat/mass transfer problems in a three‐dimensional porous structure
Authors: Yoshino M. , Inamuro T. 
Published: August 2003

AbstractThe lattice Boltzmann method (LBM) for a binary miscible fluid mixture is applied to problems of transport phenomena in a three‐dimensional porous structure. Boundary conditions for the particle distribution function of a diffusing component are described in detail. Flow characteristics and concentration profiles of diffusing species at a pore scale in the structure are obtained at various Reynolds numbers. At high Reynolds numbers, the concentration profiles are highly affected by the flow convection and become completely different from those at low Reynolds numbers. The Sherwood numbers are calculated and compared in good agreement with available experimental data. The results indicate that the present method is useful for the investigation of transport phenomena in porous structures. Copyright © 2003 John Wiley & Sons, Ltd.