bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polybrominated diphenyl ethers in biota and sediments of the Pearl River Estuary, South China
Authors: Xiang Cai-Hong , Luo Xiao-Jun , Chen She-Jun , Yu Mei , Mai Bi-Xian , Zeng Eddy Y. 
Published: June 2007

Abstract
Polybrominated diphenyl ethers (PBDEs) were analyzed in three invertebrate species, five fish species with different living and feeding habits, and surface sediments collected from the Pearl River Estuary, South China. The concentrations of 10 PBDE congeners (BDEs 28, 47, 66, 99, 100, 85, 154, 153, 138, and 183) ranged from 34.1 to 444.5 ng/g lipid and from 9.88 to 39.0 ng/g organic carbon in biota and sediment samples, respectively. In sediments and some biota samples, BDE 209 was found as the major congener, ranging from nondetectable to 623.5 ng/g lipid in biota samples and from 792 to 4,137 ng/g organic carbon in sediment samples. Different levels of PBDEs in various biota species were attributed to the different feeding habits of the aquatic species or their ability to metabolize PBDE. Different congener profiles between the biota and sediment samples were observed and attributed to the bioaccumulation potential or the ability to metabolize individual BDE congeners. Polybrominated diphenyl ether levels in the biota from the Pearl River Estuary correlated well with lipid contents but did not correlate with the biota lengths. The distribution of biota-sediment accumulation factors for individual PBDE congeners was consistent with the general pattern predicted from a widely used bioaccumulation model.
Influence of dissolved organic matter on the complexation of mercury under sulfidic conditions
Authors: Miller Carrie L. , Mason Robert P. , Gilmour Cynthia C. , Heyes Andrew 
Published: June 2007

AbstractThe complexation of Hg under sulfidic conditions influences its bioavailability for microbial methylation. Neutral dissolved Hg-sulfide complexes are readily available to Hg-methylating bacteria in culture, and thermodynamic models predict that inorganic Hg-sulfide complexes dominate dissolved Hg speciation under natural sulfidic conditions. However, these models have not been validated in the field. To examine the complexation of Hg in natural sulfidic waters, octanol/water partitioning methods were modified for use under environmentally relevant conditions, and a centrifuge ultrafiltration technique was developed. These techniques demonstrated much lower concentrations of dissolved Hg-sulfide complexes than predicted. Furthermore, the study revealed an interaction between Hg, dissolved organic matter (DOM), and sulfide that is not captured by current thermodynamic models. Whereas Hg forms strong complexes with DOM under oxic conditions, these complexes had not been expected to form in the presence of sulfide because of the stronger affinity of Hg for sulfide relative to its affinity for DOM. The observed interaction between Hg and DOM in the presence of sulfide likely involves the formation of a DOM-Hg-sulfide complex or results from the hydrophobic partitioning of neutral Hg-sulfide complexes into the higher-molecular-weight DOM. An understanding of the mechanism of this interaction and determination of complexation coefficients for the Hg-sulfide-DOM complex are needed to adequately assess how our new finding affects Hg bioavailability, sorption, and flux.
Risk of weathered residual Exxon Valdez oil to pink salmon embryos in Prince William Sound
Authors: Brannon Ernest L. , Collins Keya M. , Cronin Mathew A. , Moulton Lawrence L. , Parker Keith R. , Wilson William 
Published: June 2007

Abstract
It has been hypothesized that pink salmon eggs incubating in intertidal streams transecting Prince William Sound (PWS) beaches oiled by the Exxon Valdez oil spill were exposed to lethal doses of dissolved hydrocarbons. Since polycyclic aromatic hydrocarbon (PAH) levels in the incubation gravel were too low to cause mortality, the allegation is that dissolved high-molecular-weight hydrocarbons (HPAH) leaching from oil deposits on the beach adjacent to the streams were the source of toxicity. To evaluate this hypothesis, we placed pink salmon eggs in PWS beach sediments containing residual oil from the Exxon Valdez oil spill and in control areas without oil. We quantified the hydrocarbon concentrations in the eggs after three weeks of incubation. Tissue PAH concentrations of eggs in oiled sediments were generally &lt;100 ppb and similar to background levels on nonoiled beaches. Even eggs in direct contact with oil in the sediment resulted in tissue PAH loads well below the lethal threshold concentrations established in laboratory bioassays, and very low concentrations of HPAH compounds were present. These results indicate that petroleum hydrocarbons dissolved from oil deposits on intertidal beaches are not at concentrations that pose toxic risk to incubating pink salmon eggs. The evidence does not support the hypothesis that interstitial pore water in previously oiled beaches is highly toxic.
Adverse effects of chronic copper exposure in larval northern leopard frogs (Rana pipiens)
Authors: Chen Te-Hao , Gross Jackson A. , Karasov William H. 
Published: June 2007

Abstract
Northern leopard frogs (Rana pipiens) were exposed to environmentally relevant concentrations of copper in water (control and 5, 25, and 100 μg/L, as CuSO4) in a static renewal system for 154 d from posthatch stage to metamorphosis. After 10 d of copper exposure (from Gosner stages 19–25), survival of tadpoles was not significantly different between treatments (averages range from 96.7 to 99.3%), but a significantly higher incidence of deformities (p &lt; 0.05) was observed in the 100-μg/L treatment. Tadpole growth rate was decreased in the 25- and 100-μg/L treatments relative to controls. Tadpole survival, swimming performance, percent metamorphosis, time to metamorphosis, and survival during and time required for tail resorption were also negatively affected in the 100-μg/L treatment. Copper concentrations in tadpole tissues ranged from 46.5 to 769.5 mg/kg dry mass and were positively related to copper concentrations in the water. In conclusion, copper was shown to affect development, growth, survival, and behavior in larval northern leopard frogs at ecologically relevant concentrations. The existing U.S. Environmental Protection Agency freshwater-quality chronic criterion for copper appears to be protective for larval Rana pipiens.
Effect of dichlorvos on the acetylcholinesterase from tambaqui (Colossoma macropomum) brain
Authors: Assis Caio Rodrigo Dias , Amaral Ian Porto Gurgel , Castro Patrícia Fernandes , Carvalho Luiz Bezerra , Bezerra Ranilson Souza 
Published: June 2007

Abstract
Dichlorvos is an acutely toxic organophosphorous pesticide that is known as a classical acetylcholinesterase (AChE; EC 3.1.1.7) inhibitor. Here, the brain AChE from the important Amazonian fish tambaqui (Colossoma macropomum) was assayed in the presence of this insecticide and also of deltamethrin, a classical sodium and potassium channel inhibitor (negative control). Four tissue homogenates were analyzed in triplicate for AChE activity using acetylthiocholine as the substrate and 5,5′-dithiobis(2-nitrobenzoic) acid (DTNB) as the color-developing agent. Each tissue homogenate represented pooled brains from five fish. The inhibitory effect of dichlorvos on AChE activities was determined at concentrations from 0.001 to 10 ppm and compared to controls. This effect followed an exponential decay model (y = 9.420 + 26.192e(–x/5.380); r2 = 0.989), presenting IC50 (the concentration of dichlorvos that is required for 50% of AChE inhibition) of 0.081 ppm (0.368 μmol/L). No effect was observed for the deltamethrin, and the concentration 0.0452 μmol/L of dichlorvos was significantly different from this control. These results suggest that tambaqui brain AChE can be proposed as a biomarker for dichlorvos and can be used as a tool for aquatic environment monitoring.
Development and validation of a 2,000-gene microarray for the fathead minnow (Pimephales promelas)
Authors: Larkin Patrick , Villeneuve Daniel L. , Knoebl Iris , Miracle Ann L. , Carter Barbara J. , Liu Li , Denslow Nancy D. , Ankley Gerald T. 
Published: June 2007

AbstractGene microarrays provide the field of ecotoxicology new tools to identify mechanisms of action of chemicals and chemical mixtures. Herein we describe the development and application of a 2,000-gene oligonucleotide microarray for the fathead minnow Pimephales promelas, a species commonly used in ecological risk assessments in North America. The microarrays were developed from various cDNA and subtraction libraries that we constructed. Consistency and reproducibility of the microarrays were documented by examining multiple technical replicates. To test application of the fathead minnow microarrays, gene expression profiles of fish exposed to 17β-estradiol, a well-characterized estrogen receptor (ER) agonist, were examined. For these experiments, adult male fathead minnows were exposed for 24 h to waterborne 17β-estradiol (40 or 100 ng/L) in a flow-through system, and gene expression in liver samples was characterized. Seventy-one genes were identified as differentially regulated by estradiol exposure. Examination of the gene ontology designations of these genes revealed patterns consistent with estradiol's expected mechanisms of action and also provided novel insights as to molecular effects of the estrogen. Our studies indicate the feasibility and utility of microarrays as a basis for understanding biological responses to chemical exposure in a model ecotoxicology test species.
Diamondback terrapins, Malaclemys terrapin, as a sentinel species for monitoring mercury pollution of estuarine systems in South Carolina and Georgia, USA
Authors: Blanvillain Gaëlle , Schwenter Jeffrey A. , Day Rusty D. , Point David , Christopher Steven J. , Roumillat William A. , Owens David W. 
Published: June 2007

Abstract
Total mercury concentrations were measured in diamondback terrapin blood and scutes collected from four sites in South Carolina, USA, and at a superfund site in Brunswick, Georgia, USA. There was a strong correlation between mercury concentrations in the two terrapin body compartments (Kendall's tau = 0.79, p &lt; 0.001). Mercury concentrations in terrapin scute and blood and in salt marsh periwinkles, Littoraria irrorata, were significantly higher in Brunswick (scute x̄ = 3810.2 ng/g, blood x̄ = 746.2 ng/g) than from all other sites (scute x̄ = 309.5 ng/g, blood x̄ = 43.2 ng/g, p &lt; 0.001). Seasonal fluctuations of total mercury in the blood and scutes of terrapins collected in the Ashley River, South Carolina, were significantly lower in August than in April, June, or October in blood (p &lt; 0.001); however, scute concentrations did not vary seasonally. Overall, we found higher concentrations of mercury in the scutes of females than males (n = 32, p &lt; 0.05). Larger females may preferentially prey on larger food items, like large periwinkles, which had significantly higher mercury levels in their body tissues than smaller periwinkles (p &lt; 0.001). Methylmercury levels in terrapin scutes were measured, revealing that 90% of the total mercury stored in this compartment was in the organic form. A methylmercury biomagnification factor of 173.5 was calculated from snails to terrapin scutes, and we found that mercury levels in scutes were representative of the mercury levels in other compartments of the ecosystem. These findings show that terrapin scutes are good predictors of mercury pollution and that this species could be used as a bioindicator for assessing mercury contamination of estuarine systems.
A survey of horse owners in Great Britain regarding horses in their care. Part 2: Risk factors for recurrent airway obstruction
Authors: HOTCHKISS J. W. , REID S. W. J. , CHRISTLEY R. M. 
Published: June 2007

Summary Reasons for performing study: Recurrent airway obstruction (RAO) is a commonly encountered respiratory condition of horses. Despite this, the epidemiology of this predominately manageable and reversible disease in Great Britain has been largely ignored. Objectives: To estimate the prevalence of RAO in the general horse population of Great Britain and to investigate possible risk factors for RAO associated with management or early life. Methods: Horse owners were surveyed using a self‐administered postal questionnaire that contained a risk‐screening questionnaire (RSQ) designed to identify horses with RAO. These owners were randomly selected, following geographical stratification, using 2‐stage cluster sampling of veterinary practices and their clients. Multilevel, multivariable logistic regression models were used to investigate risk factors for RAO in the selected horse population. Results: The estimated true prevalence of RAO in the selected horse population was 14.0% (95%CI 10.7–17.4%). Risk factors for RAO identified in a general horse management logistic regression model included increasing age and exposure to an urbanised environment. Recurrent airway obstruction has long been associated with mature horses while the association with an urbanised environment could be related to different management practices in these areas or possibly air pollution could be involved. The second model associated exposure to hay and respiratory infection in early life with a horse having RAO in later life. Challenges to the respiratory system in early life may be involved in the development of this disease. Conclusions and potential relevance: Recurrent airway obstruction is a significant health problem in the horse population of Great Britain. This form of epidemiological investigation highlights potential risk factors for the disease.
Equine idiopathic cheek teeth fractures: Part 2: A practice‐based survey of 147 affected horses in Britain and Ireland
Authors: TAYLOR L. , DIXON P. M. 
Published: June 2007

Summary Reasons for performing study: There is limited information on the prevalence of idiopathic cheek teeth (CT) fractures in the general equine population and on which CT are most commonly affected. Objectives: To obtain information on the prevalence of fracture patterns and clinical details of idiopathic CT fractures. Methods: Details of cases with idiopathic CT fractures encountered were obtained via a questionnaire sent to suitably experienced veterinary practitioners and equine dental technicians (EDTs). Results: Details of 147 horses that suffered a total of 182 idiopathic CT fractures; and median 0.4% (range 0.07–5.9%) of horses examined were diagnosed with such fractures; 133 maxillary CT and 49 mandibular CT fractures were found; maxillary Triadan 09s and 10s were preferentially fractured (46% of all fractured CT); fracture patterns included maxillary CT slab fractures (through 1st and 2nd pulp chambers) in 87 teeth (48% of all fractured CT), maxillary CT midline sagittal fractures (through the infundibula) in 31 CT; and various other types of maxillary CT fractures in 15 CT. In the mandibular CT, lateral slab fractures (through the 4th and 5th pulp chambers) were found in 28 CT and a variety of other fracture patterns in the other 21 mandibular CT. Clinical signs included quidding in 33% of cases, bitting and behavioural problems (29%) and halitosis (12%), however 39% of horses with idiopathic CT fractures were asymptomatic. Treatments included oral extraction of the smaller dental fragment in 37% of cases, extraction of the entire fractured tooth (9%); removal of sharp edges on the remaining part of fractured tooth (14%); reduction of height of the opposite tooth (4%); other surgical or endodontic treatments, or referral of case for further investigation and treatment (10%); or no specific treatment (39%). Following treatment, 81% of cases were reported to be asymptomatic, 6% had ongoing clinical problems and the outcome was unclear in 13% of cases. Conclusions: Idiopathic CT fractures are present in approximately 0.4% of horses and may variably cause none to severe clinical signs. Most idiopathic CT fractures respond well to treatment. Potential relevance: Understanding of the prevalence, clinical findings and treatment of idiopathic CT fractures will improve management of these disorders.
Magnetic resonance imaging evaluation of 264 horses with foot pain: The podotrochlear apparatus, deep digital flexor tendon and collateral ligaments of the distal interphalangeal joint
Authors: DYSON S. , MURRAY R. 
Published: June 2007

Summary Reasons for performing study: To improve understanding of the interrelationships between injuries of the podotrochlear apparatus and deep digital flexor tendon (DDFT). Hypotheses: There is a difference in frequency of different types of lesions at different anatomical sites of the DDFT. Lesions of the collateral sesamoidean ligament (CSL), distal sesamoidean impar ligament (DSIL), distal interphalangeal (DIP) joint and navicular bursa are seen in association with lesions of the navicular bone. Methods: The magnetic resonance (MR) images of 264 horses with unilateral or bilateral foot pain were analysed and graded. Descriptive statistics were performed to establish the frequency of occurrence of DDFT lesion types at different anatomical levels, and lesions of the CSL, DSIL, navicular bursa, DIP joint and collateral ligaments (CLs) of the DIP joint. A Chi‐square test was used to test for a difference in the proportion of navicular bone grades between limbs with and without DDFT lesions at each level, and to compare navicular bone grades for limbs with and without each of DSIL, CSL, navicular bursa or DIP joint lesions. Results: Lesions of the DDFT occurred in 82.6% of limbs, occurring most commonly at the level of the CSL (59.4%) and the navicular bone (59.0%). Core lesions predominated at the level of the proximal phalanx (90.3%), whereas at the level of the CSL and navicular bone core lesions, sagittal splits and dorsal abrasions were most common. There was a positive association between DDFT lesions and navicular bone pathology involving all aspects of the bone. Lesions of the DSIL (38.2% limbs) were more common than those of the CSL (10.5%), but the presence of either was associated with abnormalities of the navicular bone, especially involving the proximal or distal borders and the medulla. Conclusions and clinical relevance: There are close interactions between injuries of the components of the podotrochlear apparatus, the DDFT, the navicular bursa and the DIP joint. Further knowledge about the biomechanical risk factors for injury may have importance for both disease prevention and management.
Hybrid modeling and dynamics of a controlled reverse flow reactor
Authors: Mancusi Erasmo , Russo Lucia , Brasiello Antonio , Crescitelli Silvestro , di Bernardo Mario 
Published: June 2007

AbstractA hybrid system approach is adopted to study the dynamic behavior of a controlled reverse flow reactor, where the occurrence of flow inversions is caused by a feedback control strategy. With this approach it is analyzed, theoretically and numerically a typical behavior of hybrid systems: Zeno phenomena. Hybrid system theory is also adopted to define a suitable Poincarè map that is a composition of two switching maps. Based on the Poincaré map an efficient methodology is developed for the continuation of limit cycles, and detection of local bifurcations as the set‐point value, and inlet temperature are varied. This analysis shows that Zeno states can be coexisting with symmetric and asymmetric periodic regimes in a wide range of the parameters. The analysis of the nonlinear behavior and Zeno phenomena gives an insight on the limits of some model assumptions, and how these assumptions should be removed to avoid the unphysical response of Zeno executions. Considering a time delay due to the valves in the reactor, the unphysical Zeno state is removed, while Zeno like oscillations are shown to be still persistent. © 2007 American Institute of Chemical Engineers AIChE J, 2007
Hydrothermal synthesis of mesoporous materials from diatomaceous earth
Authors: Jing Zhenzi , Maeda Hirotaka , Ioku Koji , Ishida Emile H. 
Published: June 2007

AbstractHydrothermal synthesis of mesoporous materials from diatomaceous earth has been carried out under saturated steam pressure (0.2–1.56 MPa) at 393–473 K for up to 72 h by slaked lime introduction. During the hydrothermal synthesis process, calcium silicate hydrate (CSH) was among the first phase formed and invariably appeared before tobermorite. The CSH formation seemed to exert a positive effect on the strength development and pore size evolution initially; whilst the tobermorite formation appeared to further enhance the strength and narrow the pore size. With curing at 473 K for 18 h, both of the strength and pore size distribution tended to reach optimal at which the pore size distribution also ranges between mesoporous area (2–50 nm in diameter). The highest strength seemed to coincide with the finest pore size distribution of the synthesized porous material during hydrothermal processing in this study. © 2007 American Institute of Chemical Engineers AIChE J, 2007
Electronic Aptamer‐Based Sensors
Authors: Willner Itamar , Zayats Maya 
Published: June 2007

AbstractThe selection of aptamers—nucleic acids that specifically bind low‐molecular‐weight substrates or proteins—by the SELEX (systematic evolution of ligands by exponential enrichment) procedure has attracted recent efforts directed to the development of new specific recognition units. In particular, extensive activities have been directed to the application of aptamers as versatile materials for the design of biosensors. The Minireview summarizes the recent accomplishments in developing electronic aptamer‐based sensors (aptasensors), which include electrochemical, field‐effect transistor, and microgravimetric quartz crystal microbalance sensors, and describes methods to develop amplified aptasensor devices and label‐free aptasensors.
Thermal degradations of chlorinated natural rubber from latex and chlorinated natural rubber from solution
Authors: Cai Ying , Li Si‐Dong , Li Cheng‐Peng , Li Pu‐Wang , Wang Chen , Lv Ming‐Zhe , Xu Kui 
Published: June 2007

AbstractThe thermal degradations of chlorinated natural rubbers from latex (CNR‐L) and from solution (CNR‐S) under nitrogen atmosphere were studied with thermogravimetric analysis (TGA). The thermal degradations of CNR‐L and CNR‐S are one‐step reaction. The shapes of the thermogravimetric and derivative thermogravimetric curves are similar. The degradation temperatures of CNR‐L and CNR‐S increase linearly with the increment of heating rates. The heating rate hardly affects the thermal degradation rates of CNR‐L and CNR‐S at the various degradation stages. The thermal degradations of CNR‐S and CNR‐L are dehydrochlonation reactions. The reaction activation energy (E) of CNR, at the first stage, is around 100 kJ/mol. After that, E remains relatively steady (80–140 kJ/mol). At the last stage, E rises rapidly (130–270 kJ/mol). The variation tendency of frequency factor (A) is similar to that of E. As the initial degradation temperature T0 of CNR‐L is 10.9°C lower than that of CNR‐S, the thermal stability of CNR‐S is better than that of CNR‐L, which may be caused by the difference of molecular structure between CNR‐L and CNR‐S, as FTIR results indicate that there are more OH, CO and COO groups in the CNR‐L molecular chains. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007