bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and characterization of nickel-spiked freshwater sediments for toxicity tests: Toward more environmentally realistic nickel partitioning
Authors: Brumbaugh William G. , Besser John M. , Ingersoll Christopher G. , May Thomas W. , Ivey Chris D. , Schlekat Christian E. , Garman Emily Rogevich 
Published: May 2013

Abstract

Two spiking methods were compared and nickel (Ni) partitioning was evaluated during a series of toxicity tests with 8 different freshwater sediments having a range of physicochemical characteristics. A 2-step spiking approach with immediate pH adjustment by addition of NaOH at a 2:1 molar ratio to the spiked Ni was effective in producing consistent pH and other chemical characteristics across a range of Ni spiking levels. When Ni was spiked into sediment having a high acid-volatile sulfide and organic matter content, a total equilibration period of at least 10 wk was needed to stabilize Ni partitioning. However, highest spiking levels evidently exceeded sediment binding capacities; therefore, a 7-d equilibration in toxicity test chambers and 8 volume-additions/d of aerobic overlying water were used to avoid unrealistic Ni partitioning during toxicity testing. The 7-d pretest equilibration allowed excess spiked Ni and other ions from pH adjustment to diffuse from sediment porewater and promoted development of an environmentally relevant, 0.5- to 1-cm oxic/suboxic sediment layer in the test chambers. Among the 8 different spiked sediments, the logarithm of sediment/porewater distribution coefficient values (log Kd) for Ni during the toxicity tests ranged from 3.5 to 4.5. These Kd values closely match the range of values reported for various field Ni-contaminated sediments, indicating that testing conditions with our spiked sediments were environmentally realistic. Environ Toxicol Chem 2013;32:2482–2494. © 2013 SETAC
Recent observations of high mass density polar mesospheric clouds: A link to space traffic?
Authors: Siskind David E. , Stevens Michael H. , Hervig Mark E. , Randall Cora E. 
Published: May 2013

AbstractObservations of polar mesospheric clouds by the Aeronomy of Ice in the Mesosphere Explorer show that for the Northern summers of 2007–2010, the cloud ice water content (IWC) and occurrence frequency varied with the meteorological forcing from the Southern winter stratosphere. With the increase in solar flux in the last two years, expectations were that the clouds would decrease due to reduced water vapor (H2O) and/or higher temperatures. Surprisingly, we observe more clouds in 2011 and 40% greater IWC in 2011 and 2012. The increase is particularly pronounced in the clouds with highest IWC. These high IWC clouds are associated with significant enhancements in total H2O (vapor and ice). We suggest this implies an additional source of H2O and that this is provided by space traffic exhaust. A preliminary estimate of the H2O released from summertime space traffic over the last six years is qualitatively consistent with this suggestion.
Strengthening of ocean heat uptake efficiency associated with the recent climate hiatus
Authors: Watanabe Masahiro , Kamae Youichi , Yoshimori Masakazu , Oka Akira , Sato Makiko , Ishii Masayoshi , Mochizuki Takashi , Kimoto Masahide 
Published: May 2013

AbstractThe rate of increase of global‐mean surface air temperature (SATg) has apparently slowed during the last decade. We investigated the extent to which state‐of‐the‐art general circulation models (GCMs) can capture this hiatus period by using multimodel ensembles of historical climate simulations. While the SATg linear trend for the last decade is not captured by their ensemble means regardless of differences in model generation and external forcing, it is barely represented by an 11‐member ensemble of a GCM, suggesting an internal origin of the hiatus associated with active heat uptake by the oceans. Besides, we found opposite changes in ocean heat uptake efficiency (κ), weakening in models and strengthening in nature, which explain why the models tend to overestimate the SATg trend. The weakening of κ commonly found in GCMs seems to be an inevitable response of the climate system to global warming, suggesting the recovery from hiatus in coming decades.
Overturning circulation driven by breaking internal waves in the deep ocean
Authors: Nikurashin Maxim , Ferrari Raffaele 
Published: May 2013

AbstractA global estimate of the water‐mass transformation by internal wave‐driven mixing in the deep ocean is presented. The estimate is based on the energy conversion from tidal and geostrophic motions into internal waves combined with a turbulent mixing parameterization. We show that internal wave‐driven mixing in the deep ocean can sustain 20–30 Sv of water‐mass transformation. One third or more of this transformation is attributed to lee waves generated by geostrophic motions flowing over rough topography, primarily in the Southern Ocean. While these results are uncertain due to many assumptions, poorly constrained parameters and data noise that enter in the calculation, the result that lee wave‐driven mixing plays an important role in the abyssal ocean circulation is likely robust. The implication is that lee wave‐driven mixing should be represented in ocean and climate models, but currently it is not.
The influence of hyporheic exchange on reach‐scale water budgets in a Precambrian Shield catchment, Quebec, Canada
Authors: Zanatta Ryan C. , Carey Sean K. , Richardson Murray 
Published: May 2013

AbstractThe influence of hyporheic exchange on water and solute budgets of streams is widely identified as important; yet, there is a notable absence of research identifying its role in Precambrian Shield headwater streams. This research addressed this shortcoming by quantifying the proportions of solute mass loss, net and gross water gains and losses for selected reaches over a single summer recession period. Six conservative tracer injections were performed on nine reaches of a 2.94‐km2 catchment in Gatineau Park, Quebec, Canada, from July to November, 2011. High solute exchange occurred for all reaches despite most showing positive net discharge. Solute losses in stream reaches typically exceeded 10%, and substantial gross water losses and gains indicate a high degree of bi‐directional water exchange along stream reaches. Both solute loss and the fraction of channel water involved in hyporheic exchange increased throughout the summer in response to a decrease in discharge and increase in the time of contact. Results support the assertion that reductions in groundwater contributions to streamflow throughout the summer baseflow period allow for greater exchange of water through hyporheic flowpaths, which constitute the majority of gross channel losses and gains. Spatial (inter‐reach) variability in mass loss has been previously ascribed to watershed control on exchange potential. In this catchment, net discharge and gross hydrologic gains were inversely related to the average flowpath gradients within the valley bottom and local hillslope contributing areas. Copyright © 2013 John Wiley & Sons, Ltd.
Assessing regression‐based statistical approaches for downscaling precipitation over North America
Authors: Chen Jie , Brissette François P. , Leconte Robert 
Published: May 2013

AbstractThis paper assesses linear regression‐based methods in downscaling daily precipitation from the general circulation model (GCM) scale to a regional climate model (RCM) scale (45‐ and 15‐km grids) and down to a station scale across North America. Traditional downscaling experiments (linking reanalysis/dynamical model predictors to station precipitation) as well as nontraditional experiments such as predicting dynamic model precipitation from larger‐scale dynamic model predictors or downscaling dynamic model precipitation from predictors at the same scale are conducted. The latter experiments were performed to address predictability limit and scale issues. The results showed that the downscaling of daily precipitation occurrence was rarely successful at all scales, although results did constantly improve with the increased resolution of climate models. The explained variances for downscaled precipitation amounts at the station scales were low, and they became progressively better when using predictors from a higher‐resolution climate model, thus showing a clear advantage in using predictors from RCMs driven by reanalysis at its boundaries, instead of directly using reanalysis data. The low percentage of explained variances resulted in considerable underestimation of daily precipitation mean and standard deviation. Although downscaling GCM precipitation from GCM predictors (or RCM precipitation from RCM predictors) cannot really be considered downscaling, as there is no change in scale, the exercise yields interesting information as to the limit in predictive ability at the station scale. This was especially clear at the GCM scale, where the inability of downscaling GCM precipitation from GCM predictors demonstrates that GCM precipitation‐generating processes are largely at the subgrid scale (especially so for convective events), thus indicating that downscaling precipitation at the station scale from GCM scale is unlikely to be successful. Although results became better at the RCM scale, the results indicate that, overall, regression‐based approaches did not perform well in downscaling precipitation over North America. Copyright © 2013 John Wiley & Sons, Ltd.
Global sensitivity analysis of hydrologic processes in major snow‐dominated mountainous river basins in Colorado
Authors: Sanadhya Pranay , Gironás Jorge , Arabi Mazdak 
Published: May 2013

AbstractThe performance of watershed models in simulating stream discharge depends on the adequate representation of important watershed processes. In snow‐dominated systems, snow, surface and subsurface hydrologic processes comprise a complex network of nonlinear interactions that influence the magnitude and timing of discharge. This study aims to identify critical processes and interactions that control discharge hydrographs in five major mountainous snow‐dominated river basins in Colorado, USA. A comprehensive watershed model (Soil and Water Assessment Tool) and a variance‐based global sensitivity analysis technique (Fourier Amplitude Sensitivity Test) were used in conjunction to identify critical models parameters and processes that they represent. Average monthly streamflow and streamflow root mean square error over a period of 20 years were used as two separate objective functions in this analysis. Examination of the sensitivity of monthly streamflow revealed the influence of parameters on flow volume, whereas the sensitivity of streamflow root mean square error also exposed the influence of parameters on the timing of the hydrographs. A stability analysis was performed to investigate the computational requirements for a robust sensitivity analysis. Results show that streamflow volume is mostly influenced by shallow subsurface processes, whereas interactions between groundwater and snow processes were the key in the timing of streamflows. A large majority of important parameters were common among all study watersheds, which underlies the prospect for regionalization of process‐based hydrologic modelling in headwater river basins in Colorado. Copyright © 2013 John Wiley & Sons, Ltd.
Photochromic Diarylethene Derivatives Bearing Hydrophilic Substituents
Authors: Shoji Yuichiro , Yagi Akira , Horiuchi Masahiro , Morimoto Masakazu , Irie Masahiro 
Published: May 2013

AbstractPhotochromic diarylethene derivatives bearing hydrophilic N,N‐bis(2‐(2‐(2‐methoxyethoxy)ethoxy)ethyl)sulfonamide (SO2NTEG2) (1–3) or myo‐inositol (4–6) substituents were synthesized. Although the solubility in aqueous solution of the derivatives containing the four tri(ethylene glycol) chains was relatively poor, the solubility was improved by introducing two myo‐inositol residues. The derivatives could be dissolved even in pure water and underwent photochromism upon alternate irradiation with ultraviolet (UV) and visible light, in both organic and aqueous solutions. The absorption maxima of the open‐ and closed‐ring isomers of these derivatives and the photostationary conversion ratios from the open‐ to the closed‐ring isomers upon UV irradiation did not change much, even when the solvent polarity was changed. These results indicate that the diarylethene derivatives are mono‐molecularly dissolved in aqueous solution and that intermolecular interactions between the derivatives are negligible when the concentration is less than 1×10−4 mol⋅L−1.
X-ray–verified fractures are associated with finite element analysis–derived bone strength and trabecular microstructure in young adult men
Authors: Rudäng Robert , Darelid Anna , Nilsson Martin , Mellström Dan , Ohlsson Claes , Lorentzon Mattias 
Published: May 2013

ABSTRACT

It has been suggested that fracture during childhood could be a predictor of low peak bone mass and thereby a potential risk factor for osteoporosis and fragility fractures later in life. The aim of this cross-sectional, population-based study was to investigate whether prevalent fractures, occurring from birth to young adulthood, were related to high-resolution peripheral quantitative computed tomography (HR-pQCT)–derived trabecular and cortical microstructure, as well as bone strength estimated by finite element (FEA) analysis of the radius and tibia in 833 young adult men around the time of peak bone mass (ages 23 to 25 years). In total, 292 subjects with prevalent X-ray–verified fractures were found. Men with prevalent fractures had lower trabecular bone volume fraction (BV/TV) at the radius (5.5%, p &lt; 0.001) and tibia (3.7%, p &lt; 0.001), as well as lower cortical thickness (5.1%, p &lt; 0.01) and cortical cross-sectional area (4.1%, p &lt; 0.01) at the tibia. No significant differences were seen for the cortical porosity or mean pore diameter. Using a logistic regression model (including age, smoking, physical activity, calcium intake, height, and weight as covariates), every SD decrease of FEA-estimated failure load was associated with an increased prevalence of fractures at both the radius (odds ratio [OR] 1.22 [1.03–1.45]) and tibia (OR 1.32 [1.11–1.56]). Including dual-energy X-ray absorptiometry (DXA)–derived radius areal bone mineral density (aBMD), cortical thickness, and trabecular BV/TV simultaneously in a logistic regression model (with age, smoking, physical activity, calcium intake, height, and weight as covariates), BV/TV was inversely and independently associated with prevalent fractures (OR 1.28 [1.04–1.59]), whereas aBMD and cortical thickness were not (OR 1.19 [0.92–1.55] and OR 0.91 [0.73–1.12], respectively). In conclusion, prevalent fractures in young adult men were associated with impaired trabecular BV/TV at the radius, independently of aBMD and cortical thickness, indicating that primarily trabecular bone deficits are of greatest importance for prevalent fracture in this population. © 2013 American Society for Bone and Mineral Research.
The Existence of Mixed Orthogonal Arrays with Four and Five Factors of Strength Two
Authors: Chen Guangzhou , Ji Lijun , Lei Jianguo 
Published: May 2013

AbstractSymmetric orthogonal arrays and mixed orthogonal arrays are useful in the design of various experiments. They are also a fundamental tool in the construction of various combinatorial configurations. In this paper, we investigated the mixed orthogonal arrays with four and five factors of strength two, and proved that the necessary conditions of such mixed orthogonal arrays are also sufficient with several exceptions and one possible exception.
Directional synthesis of liquid higher olefins through catalytic transformation of bio‐oil
Authors: Yuan Yanni , Bi Peiyan , Fan Minghui , Zhang Zhaoxia , Jiang Peiwen , Li Quanxin 
Published: May 2013

AbstractBACKGROUNDCatalytic transformation of bio‐oil into higher olefins can provide valuable bio‐fuels and chemicals used in the manufacture of high‐octane gasoline, detergents, plasticizers and other petrochemicals. This work explores the production of higher olefins from bio‐oil through catalytic cracking of bio‐oil along with light olefins oligomerization.RESULTSFor bio‐oil catalytic cracking, the olefins yield reached 43.8 C‐mol% with near‐complete bio‐oil conversion. The oxygenated organic compounds in bio‐oil go through deoxygenation, cracking and hydrogen transfer reactions and form light olefins over the zeolite acid sites. For the oligomerization of light olefins, the highest selectivity and yield of C5+ olefins over the LTGO catalyst reached 85.4 C‐mol% and 326.7 g kg−1cata h−1, respectively. Main products below 300°C were C6=—C12= olefins, originating from light olefin oligomerization. The influences of the reaction conditions were investigated in detail, and the reaction mechanism was addressed.CONCLUSIONBio‐oil can be catalytically converted to C2=–C4= light olefins over HZSM‐5, and further selectively transformed to C5+ high olefins via the oligomerization of light olefins over LTGO. The transformation of bio‐oil to higher olefins may be useful for the production of bio‐fuels and high value chemicals using renewable biomass. © 2013 Society of Chemical Industry
Sonographic diagnosis of bilateral pneumothorax following an acupuncture session
Authors: Harriott Allison , Mehta Ninfa , Secko Michael , Romney Marie‐Laure S. 
Published: May 2013

ABSTRACTWe present the case of a 57‐year‐old woman who presented with the acute onset of chest pain and dyspnea, which started while undergoing acupuncture for neck pain. A bedside ultrasound revealed bilateral pneumothoraces, which were confirmed radiographically. We discuss the details of the case, the sonographic features of pneumothorax, and the role of bedside ultrasonography in the assessment of an acutely dyspneic patient. © 2013 Wiley Periodicals, Inc. J Clin Ultrasound 42:27–29, 2014
Decadal prediction of interannual tropical and North Pacific sea surface temperature
Authors: Lienert Fabian , Doblas‐Reyes Francisco J. 
Published: May 2013

AbstractThe performance of a coupled climate forecast system initialized with observations, relative to the accompanying uninitialized system, to re‐forecast annual‐mean tropical and North Pacific Sea Surface Temperature (SST) departures at the decadal time scale is described. The study finds that the correlation skill of the leading Empirical Orthogonal Function (EOF) mode of North Pacific SSTs, i.e., the Pacific Decadal Oscillation (PDO), is limited to about one year, while the second mode, i.e., the North Pacific Gyre Oscillation (NPGO), is skillfully forecast throughout the 10‐year forecast range. In the tropical Pacific, it is found that the correlation skill of the leading EOF mode of tropical Pacific SSTs, i.e., El Niño Southern Oscillation (ENSO), and the second mode, i.e., ENSO‐Modoki, is limited to about two years and one year. A main contributor to forecast skill of the NPGO are the effects of the long‐term trend on Pacific SSTs while little impact of the initialization was found.
SERPINB2 down‐regulation contributes to chemoresistance in head and neck cancer
Authors: Huang Zhiquan , Li Haigang , Huang Qi , Chen Dan , Han Jingjing , Wang Lili , Pan Chanbin , Chen Weiliang , House Michael G. , Nephew Kenneth P. , Guo Zhongmin 
Published: May 2013

AbstractResistance to cisplatin‐based chemotherapy is responsible for the majority of deaths from head and neck squamous cell carcinoma (HNSCC). In this study, using genome‐wide gene expression analysis to investigate potential molecular mediators of HNSCC chemoresistance, we identified SERPINB2, a known inhibitor of extracellular serine proteinase urokinase‐type plasminogen activator (uPA), as an important candidate. Whereas SERPINB2 is known to function as a suppressor of uPA molecular cascades, many of which play important roles in tumor invasion and metastasis, a role for SERPINB2 in cancer drug resistance has not been examined. By using quantitative real‐time PCR and Western blot analysis, we determined that SERPINB2 mRNA and protein levels correlated with chemoresistance in HNSCC cell lines, and significantly lower SERPINB2 expression levels were observed in two cisplatin resistant HNSCC subclones compared to their isogenic drug‐sensitive parental lines. Immunohistochemical analysis of HNSCC tumor tissues from patients treated with neoadjuvant cisplatin‐based chemotherapy (n = 67 cases) revealed a significant association between SERPINB2 protein levels, tumor differentiation and patient relapse. Moreover, SERPINB2 down‐regulation was a strong predictor of reduced overall survival in patients with HNSCC who received cisplatin‐based chemotherapy (P = 0.001, log rank test). Studies using either siRNA‐mediated down‐regulation or forced over‐expression of SERPINB2 in HNSCC cell lines confirmed a functional role for SERPINB2 in drug resistance. The findings were further supported using chemical inhibitors of STAT3 activity (a downstream effecter of uPAR signaling pathway), showing that STAT3 suppression altered HNSCC cell line cisplatin sensitivity. This is the first report on a role for SERPINB2 in acquired resistance to cisplatin in patients with HNSCC. © 2013 Wiley Periodicals, Inc.
Zebularine inhibits the growth of A549 lung cancer cells via cell cycle arrest and apoptosis
Authors: You Bo Ra , Park Woo Hyun 
Published: May 2013

AbstractZebularine (Zeb) is a DNA methyltransferase (DNMT) inhibitor to that has an anti‐tumor effect. Here, we evaluated the anti‐growth effect of Zeb on A549 lung cancer cells in relation to reactive oxygen species (ROS) levels. Zeb inhibited the growth of A549 cells with an IC50 of approximately 70 µM at 72 h. Cell cycle analysis indicated that Zeb induced an S phase arrest in A549 cells. Zeb also induced A549 cell death, which was accompanied by the loss of mitochondrial membrane potential (MMP; ΔΨm), Bcl‐2 decrease, Bax increase, p53 increase and activation of caspase‐3 and ‐8. In contrast, Zeb mildly inhibited the growth of human pulmonary fibroblast (HPF) normal cells and lead to a G1 phase arrest. Zeb did not induce apoptosis in HPF cells. In relation to ROS level, Zeb increased ROS level in A549 cells and induced glutathione (GSH) depletion. The well‐known antioxidant, N‐acetyl cysteine (NAC) prevented the death of Zeb‐treated A549 cells. Moreover, Zeb increased the level of thioredoxin reductase 1 (TrxR1) in A549 cells. While the overexpression of TrxR1 attenuated death and ROS level in Zeb‐treated A549 cells, the downregulation of TrxR1 intensified death and ROS level in these cells. In conclusion, Zeb inhibited the growth of A549 lung cancer cells via cell cycle arrest and apoptosis. The inhibition was influenced by ROS and TrxR1 levels. © 2013 Wiley Periodicals, Inc.