bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of varying the dose of corn syrup on the insulin and glucose response to the oral sugar test
Authors: Jocelyn N. A. , Harris P. A. , Menzies‐Gow N. J. 
Published: March 2018

SummaryBackgroundThe oral sugar test (OST) is used to identify equine insulin dysregulation (ID); however only a dose of 0.15 mL/kg bwt corn syrup has been evaluated.ObjectivesTo determine the effect of varying the dose of corn syrup on insulin and glucose response to the OST and the test's ability to distinguish between ponies with a history of laminitis (PL) and without laminitis (NL).Study designRandomised crossover experiment.MethodsAfter an overnight fast, in a three‐way randomised crossover study with a 7‐day washout, 0.15, 0.3 or 0.45 mL/kg bwt corn syrup was administered orally to eight ponies (5 PL and 3 NL) and blood obtained between 0 and 120 min. Serum [insulin] and [glucose] were measured using previously validated radioimmunoassay and colorimetric assays respectively. The repeatability of and the effect of continued pasture access on the dose that best distinguished PL and NL ponies were then assessed. The effect of dose, laminitis history and fasting on serum [insulin] and [glucose] responses were assessed using mixed‐effects models.ResultsThe serum [insulin] following 0.15 mL/kg bwt were not significantly different from 0.3 mL/kg bwt at any time point, while serum [insulin] following 0.45 mL/kg bwt significantly (P<0.01) differed from 0.15 and 0.3 mL/kg bwt at all time points apart from 0 min. The serum [insulin] concentration significantly (P<0.01) differed between NL (mean 86 [95% CI 59, 113] μiu/mL) and PL (146 [95% CI 124, 167] μiu/mL) only following 0.45 mL/kg bwt at 60 min. Repeatability of serum [insulin] at 60 min following 0.45 mL/kg bwt dose under fasted conditions was 0.51. Using AUC insulin improved repeatability to 0.83. There was no significant difference between the fasted and at pasture results.Main limitationsThe OST was performed in small numbers of ponies on limited occasions.ConclusionsA dose of 0.45 mL/kg bwt corn syrup may be preferable to differentiate PL and NL ponies.
The global system‐ranking efficiency model and calculating examples with consideration of the nonhomogeneity of decision‐making units
Authors: Wang Shuhong , Sun Xiaoli 
Published: March 2018

AbstractData envelopment analyses have been widely used to evaluate the relative efficiency of decision‐making units (DMUs). However, the traditional data envelopment analysis model has not considered the problem of DMUs' nonhomogeneity. If nonhomogeneous DMUs are evaluated under the same production frontier, conclusions may not be precise. For example, some DMUs' input redundancy and output deficit cannot be adjusted as per planning results, which may lead to mistakes in management. This paper loosens the assumption of DMU homogeneity and builds a global system‐ranking efficiency model based on existing literature, which divides the problem of DMUs' nonhomogeneity into external nonhomogeneity and internal homogeneity. Data have been collected from 114 listed enterprises in China's solar power industry, and the analysis results indicate that this paper's model is stable and reliable and can be used as a reference for production managers.
Comparison of adherence to generic multi‐tablet regimens vs. brand multi‐tablet and brand single‐tablet regimens likely to incorporate generic antiretroviral drugs by breaking or not fixed‐dose combinations in HIV‐infected patients
Authors: Rwagitinywa Joseph , Lapeyre‐Mestre Maryse , Bourrel Robert , Montastruc Jean‐Louis , Sommet Agnès 
Published: March 2018

AbstractAdherence to antiretroviral (ARV) is crucial to achieve viral load suppression in HIV‐infected patients. This study aimed to compare adherence to generic multi‐tablet regimens (MTR) vs. brand MTR likely to incorporate ARV drugs without breaking fixed‐dose combinations (FDC) and brand single‐tablet regimens (STR) likely to incorporate generics by breaking the FDC. Patients aged of 18 years or over exposed to one of the generic or the brand of lamivudine (3TC), zidovudine/lamivudine (AZT/TC), nevirapine (NVP), or efavirenz (EFV), or the brand STR of efavirenz/emtricitabine/tenofovir (EFV/FTC/TDF). Adherence was measured by medication possession ratio (MPR) using both defined daily dose (DDD) and daily number of tablet recommended for adults (DNT). Adherence to generic MTR vs. brand MTR and brand STR was compared using Kruskal–Wallis. The overall median adherence was 0.97 (IQR 0.13) by DNT method and 0.97 (0.14) by DDD method. Adherence in patients exposed to generic MTR (n = 165) vs. brand MTR (n = 481) and brand STR (n = 470) was comparable by DNT and DDD methods. In conclusion, adherence to generic MTR was high and comparable with adherence to brand MTR and to STR. Utilization of DDD instead DNT to measure the MPR led to small but nonsignificant difference that has no clinical impact.
Crystal structure of the nitrosuccinate lyase CreD in complex with fumarate provides insights into the catalytic mechanism for nitrous acid elimination
Authors: Katsuyama Yohei , Sato Yukari , Sugai Yoshinori , Higashiyama Yousuke , Senda Miki , Senda Toshiya , Ohnishi Yasuo 
Published: March 2018

Enzymes belonging to the aspartase/fumarase superfamily catalyze elimination of various functional groups from succinate derivatives and play an important role in primary metabolism and aromatic compound degradation. Recently, an aspartase/fumarase superfamily enzyme, CreD, was discovered in cremeomycin biosynthesis. This enzyme catalyzes the elimination of nitrous acid from nitrosuccinate synthesized from aspartate by CreE, a flavin‐dependent monooxygenase. Nitrous acid generated by this pathway is an important precursor of the diazo group of cremeomycin. CreD is the first aspartase/fumarase superfamily enzyme that was reported to catalyze the elimination of nitrous acid, and therefore we aimed to analyze its reaction mechanism. The crystal structure of CreD was determined by the molecular replacement native‐single anomalous diffraction method at 2.18 Å resolution. Subsequently, the CreD‐fumarate complex structure was determined at 2.30 Å resolution by the soaking method. Similar to other aspartase/fumarase superfamily enzymes, the crystal structure of CreD was composed of three domains and formed a tetramer. Two molecules of fumarate were observed in one subunit of the CreD‐fumarate complex. One of them was located in the active site pocket formed by three different subunits. Intriguingly, no histidine residue, which usually functions as a catalytic acid in aspartase/fumarase superfamily enzymes, was found around the fumarate molecule in the active site. Based on the mutational analysis, we propose a catalytic mechanism of CreD, in which Arg325 acts as a catalytic acid.DatabasesThe crystal structures of CreD and the CreD‐fumarate complex were deposited to PDB under the accession numbers 5XNY and 5XNZ, respectively.EnzymesNitrosuccinate lyase CreD, EC4.3
Vapor Intrusion Screening at Petroleum UST Sites
Authors: Lahvis Matthew A. , Hers Ian , Davis Robin V. , Wright Jackie , DeVaull George E. 
Published: March 2018

AbstractDetailed site investigations to assess potential inhalation exposure and risk to human health associated with the migration of petroleum hydrocarbon vapors from the subsurface to indoor air are frequently undertaken at leaking underground storage tank (UST) sites, yet documented occurrences of petroleum vapor intrusion are extremely rare. Additional assessments are largely driven by low screening‐level concentrations derived from vapor transport modeling that does not consider biodegradation. To address this issue, screening criteria were developed from soil‐gas measurements at hundreds of petroleum UST sites spanning a range of environmental conditions, geographic regions, and a 16‐year time period (1995 to 2011). The data were evaluated to define vertical separation (screening) distances from the source, beyond which, the potential for vapor intrusion can be considered negligible. The screening distances were derived explicitly from benzene data using specified soil‐gas screening levels of 30, 50, and 100 µg/m3 and nonparametric Kaplan‐Meier statistics. Results indicate that more than 95% of benzene concentrations in soil gas are ≤30 µg/m3 at any distance above a dissolved‐phase hydrocarbon source. Dissolved‐phase petroleum hydrocarbon sources are therefore unlikely to pose a risk for vapor intrusion unless groundwater (including capillary fringe) comes in contact with a building foundation. For light nonaqueous‐phase liquid (LNAPL) hydrocarbon sources, more than 95% of benzene concentrations in soil gas are ≤30 µg/m3 for vertical screening distances of 13 ft (4 m) or greater. The screening distances derived from this analysis are markedly different from 30 to 100 ft (10 to 30 m) vertical distances commonly found cited in regulatory guidance, even with specific allowances to account for uncertainty in the hydrocarbon source depth or location. Consideration of these screening distances in vapor intrusion guidance would help eliminate unnecessary site characterization at petroleum UST sites and allow more effective and sustainable use of limited resources.
Comparison of Constant and Transient‐Source Zones on Simulated Contaminant Plume Evolution in Groundwater: Implications for Hydrogeological Risk Assessment
Authors: Thornton Steven F. , Tobin Kevin , Smith Jonathan W. N. 
Published: March 2018

AbstractContaminant fate and transport models used for hydrogeological risk assessment commonly include an assumed constant source concentration to predict downgradient concentrations in groundwater. This assumption is unrealistic in many cases where nonaqueous phase liquids (NAPLs) are the contaminant source. In this study the effect of a constant and transient (declining) source term on contaminant plume chemistry and groundwater impacts predicted by a hydrogeological risk assessment model is investigated for the release of dissolved phase constituents from an unleaded petroleum fuel light nonaqueous phase liquid (LNAPL). Two transient source models were developed: a mass balance model and an exponential decay model. Both use Raoult's Law to describe the aqueous phase partitioning and depletion of organic compounds from a multicomponentLNAPLsource to groundwater. The models were used to estimate the changingLNAPLcomposition and effective aqueous solubility of six common constituents (benzene, toluene, ethylbenzene, xylene, methyl‐tert‐butyl‐ether, and tert‐amyl‐methyl‐ether) in a representative unleaded petroleum fuel. The predicted source concentrations were then compared with groundwater quality data from a contaminated site. The source concentrations estimated from these models were propagated into a hydrogeological risk assessment model using the Remedial Targets Worksheet v3.1 developed by the Environment Agency of England and Wales. Different groundwater impacts and associated estimates of risk were predicted between the constant and transient source simulations. These are illustrated using simple calculations and established risk assessment methods. The constant‐source model predicted higher contaminant concentrations at the compliance point, which also persisted over a much longer duration. Consequently, there was a greater requirement for remedial action estimated using the hydrogeological model in scenarios that assumed a constant‐source. This could result in unnecessary remedial action in cases where no unacceptable risk is predicted when a more representative description of a declining source is used.
Spatiotemporal Variations in Microbial Communities in a Landfill Leachate Plume
Authors: Brad T. , Obergfell C. , van Breukelen B. M. , van Straalen N. M. , Röling W. F. M. 
Published: March 2018

AbstractWe examined the spatiotemporal changes of microbial communities in relation to hydrochemistry variation over time and space in an aquifer polluted by landfill leachate (Banisveld, The Netherlands). Sampling in 1998, 1999, and 2004 at the same time of the year revealed that the center of the pollution plume was hydrochemically rather stable, but its upper fringe moved to the surface over time, especially at distances greater than 40 m away from the landfill. Complex and spatiotemporal heterogeneous bacterial and eukaryotic communities were resolved using denaturing gradient gel electrophoresis (DGGE) of 16S and 18S rRNA gene fragments. Large fluctuations were noted in the eukaryotic communities associated with strongly polluted and cleaner groundwater. The bacterial communities in strongly polluted samples were different from those in cleaner groundwater in 1998 and 1999, but no longer in 2004. The temporal variation in microbial communities was greater than the spatial variation: the 1998 bacteria communities in strongly polluted groundwater were more related to each other than to those recovered in 1999 and 2004. During the three sampling periods, the bacterial communities were more stable close to the landfill than at larger distances from the landfill. Overall, pollution appears to have only a minor influence on microbial communities. The considerable spatiotemporal variation in microbial community composition may contribute to better biodegradation of pollutants. Designing management strategies for natural attenuation of aquifer pollution will benefit from further long‐term, high‐density monitoring of changes in microbial communities, their diversity and physiological properties, in relation to changes in hydrochemistry.
Natural Buffering of Groundwater Contaminants Related to Development in Fractured Rock
Authors: Metcalf Meredith J. , Robbins Gary A. 
Published: March 2018

AbstractIn rural areas of New England groundwater from fractured crystalline and sedimentary bedrock is a critical water resource. Increasingly, studies have shown that development occurring in rural areas is resulting in the impairment of water quality in fractured rock aquifers. The objective of this study was to evaluate the spatial and temporal variations in groundwater quality associated with development and evaluate the extent to which common groundwater contaminants associated with rural development may be naturally buffered. The study entailed a compilation and synthesis of over 2500 reports on domestic water quality that spanned a 30 year period. Focus was placed on the spatial distribution and temporal variations in sodium, chloride, iron, manganese, nitrate, and nitrite. Results indicate that despite significant levels of development, the amount of contamination to the bedrock has been minimal. Of the constituents examined, only the chloride concentration exhibits a systematic increase over time, but the level of chloride remained relatively low. The flux of chloride to the bedrock from deicing appears minimal despite the significant amounts of road salt used in the study area. Sodium concentrations in the bedrock remained relatively constant and appear to be buffered by ion exchange with calcium as suggested by the increase in hardness with time. Iron and manganese were present at relatively low levels but did not show any systematic trends over time. Nitrate and nitrite concentrations were very low and found to be inversely correlated with manganese and iron concentrations. This suggests that the presence of iron and manganese contribute to denitrification. This study indicated that both geochemical and biogeochemical processes are active buffering mechanisms that help shield the bedrock from contaminants associated with development.
An Injectable Apatite Permeable Reactive Barrier for In Situ 90Sr Immobilization
Authors: Vermeul Vince R. , Szecsody Jim E. , Fritz Brad G. , Williams Mark D. , Moore Robert C. , Fruchter Jonathan S. 
Published: March 2018

AbstractAn injectable permeable reactive barrier (PRB) technology was developed to sequester 90Sr in groundwater through the in situ formation of calcium‐phosphate mineral phases, specifically apatite that incorporates 90Sr into the chemical structure. This injectable barrier technology extends the PRB concept to sites where groundwater contaminants are too deep or where site conditions otherwise preclude the application of more traditional trench‐emplaced barriers. An integrated, multiscale development and testing approach was used that included laboratory bench‐scale experiments, an initial pilot‐scale field test, and the emplacement and evaluation of a 300‐feet‐long treatability‐test‐scale PRB. The apatite amendment formulation uses two separate precursor solutions, one containing a Ca‐citrate complex and the other a Na‐phosphate solution, to form apatite precipitate in situ. Citrate is needed to keep calcium in solution long enough to achieve a more uniform and areally extensive distribution of precipitate formation. In the summer of 2008, the apatite PRB technology was applied as a 91‐m‐long (300 feet) PRB on the downgradient edge of a 90Sr plume beneath the Hanford Site in Washington State. The technology was deployed to reduce 90Sr flux discharging to the Columbia River. Performance assessment monitoring data collected to date indicate that the barrier is meeting treatment objectives (i.e., 90% reduction in 90Sr concentration). The average reduction in 90Sr concentrations at four downgradient compliance monitoring locations was 95% relative to the high end of the baseline range approximately 1 year after treatment, and continues to meet remedial objectives more than 4 years after treatment.
Temperature as a Tool to Evaluate Aerobic Biodegradation in Hydrocarbon Contaminated Soil
Authors: Sweeney Robert E. , Ririe G. Todd 
Published: March 2018

AbstractThis study evaluates the theory, and some practical aspects of using temperature measurements to assess aerobic biodegradation in hydrocarbon contaminated soil. The method provides an easily applicable alternative for quantifying the rate of biodegradation and/or evaluating the performance of in situ remediation systems. The method involves two nonintrusive procedures for measuring vertical temperature profiles down existing monitoring wells; one using a thermistor on a cable for one‐time measurements and the other using compact temperature data loggers deployed for 3‐month to 1‐year period. These vertical temperature profile measurements are used to identify the depth and lateral extent of biodegradation as well as to monitor seasonal temperature changes throughout the year. The basic theory for using temperature measurements to estimate the minimum rate of biodegradation will be developed, and used to evaluate field measurements from sites in California where biodegradation of spilled petroleum hydrocarbons is due to natural processes. Following, temperature data will be used to evaluate the relative rates of biodegradation due to natural processes and soil vapor extraction (SVE) at a former refinery site in the North‐Central United States. The results from this study show that the temperature method can be a simple, cost effective tool for assessing biodegradation in the soil, and optimizing remediation systems at a wide variety of hydrocarbon spill sites.
Persistence of a Groundwater Contaminant Plume after Hydraulic Source Containment at a Chlorinated‐Solvent Contaminated Site
Authors: Matthieu D. E. , Brusseau M. L. , Guo Z. , Plaschke M. , Carroll K. C. , Brinker F. 
Published: March 2018

AbstractThe objective of this study was to characterize the behavior of a groundwater contaminant (trichloroethene, TCE) plume after implementation of a source‐containment operation at a site in Arizona. The plume resides in a quasi‐three‐layer system comprising a sand/gravel unit bounded on the top and bottom by relatively thick silty clayey layers. The system was monitored for 60 months beginning at start‐up in 2007 to measure the change in contaminant concentrations within the plume, the change in plume area, the mass of the contaminant removed, and the integrated contaminant mass discharge (CMD). The concentrations of TCE in groundwater pumped from the plume extraction wells have declined significantly over the course of operation, as have concentrations for groundwater sampled from 40 monitoring wells located within the plume. The total CMD associated with operation of the plume extraction wells peaked at 0.23 kg/d, decreased significantly within 1 year, and thereafter began an asymptotic decline to a current value of approximately 0.03 kg/d. Despite an 87% reduction in contaminant mass and a comparable 87% reduction in CMD for the plume, the spatial area encompassed by the plume has decreased by only approximately 50%. This is much less than would be anticipated based on ideal flushing and mass‐removal behavior. Simulations produced with a simplified three‐dimensional (3D) numerical model matched reasonably well to the measured data. The results of the study suggest that permeability heterogeneity, back diffusion, hydraulic factors associated with the specific well field system, and residual discharge from the source zone are all contributing to the observed persistence of the plume, as well as the asymptotic behavior currently observed for mass removal and for the reduction in CMD.
Organic Contaminants in Portland Cements Used in Monitoring Well Construction
Authors: Smith Bert , Siegel Donald , Neslund Charles , Carter Charles 
Published: March 2018

AbstractWe report the results of two independent laboratory investigations to evaluate total and leachable concentrations of glycols, glycol ethers, phenol, and other compounds in representative Type I and Type I/II Portland cement products that United States Environmental Protection Agency (EPA), The American Society of Testing and Materials (ASTM) and others recommend as annular sealants in monitoring well completions. Water well drillers also use these cements in their well completions. The EPA has included some of these compounds for analysis in their National Hydraulic Fracturing Study to evaluate the effects of hydraulic fracturing on ground‐ and surface water resources. During any contaminant investigation, materials used in monitoring or water well drilling, completion, development, and sampling must be free of the chemicals being targeted by the regulatory agency. Three of five bulk cement products we tested contained part per million (ppm) (mg/kg) concentrations of diethylene glycol, ethylene glycol, tetraethylene glycol, and triethylene glycol; chemicals added as grinding aids during manufacture. Some cements also contained ppb (µg/kg) concentrations of benzoic acid, phenols, propylene glycol, and 2‐butoxyethanol. Leaching of cured cement samples in water produced ppm (mg/L) concentrations of glycols in the supernatant. These results show that cured cements in monitoring or water wells can contaminate groundwater samples with glycols and phenol. Our findings should help prevent future sample bias and false positives when testing for glycol compounds and phenol in groundwater samples from monitoring or water wells and highlight the need to test materials or products used in monitoring or water well drilling, completions, development, and sampling to avoid false positives when sampling and analyzing for less common analytical constituents.