bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ecological limit functions relating fish community response to hydrologic departures of the ecological flow regime in the Tennessee River basin, United States
Authors: Knight Rodney R. , Murphy Jennifer C. , Wolfe William J. , Saylor Charles F. , Wales Amy K. 
Published: November 2013

ABSTRACTEcological limit functions relating streamflow and aquatic ecosystems remain elusive despite decades of research. We investigated functional relationships between species richness and changes in streamflow characteristics at 662 fish sampling sites in the Tennessee River basin. Our approach included the following: (1) a brief summary of relevant literature on functional relations between fish and streamflow, (2) the development of ecological limit functions that describe the strongest discernible relationships between fish species richness and streamflow characteristics, (3) the evaluation of proposed definitions of hydrologic reference conditions, and (4) an investigation of the internal structures of wedge‐shaped distributions underlying ecological limit functions.Twenty‐one ecological limit functions were developed across three ecoregions that relate the species richness of 11 fish groups and departures from hydrologic reference conditions using multivariate and quantile regression methods. Each negatively sloped function is described using up to four streamflow characteristics expressed in terms of cumulative departure from hydrologic reference conditions. Negative slopes indicate increased departure results in decreased species richness.Sites with the highest measured fish species richness generally had near‐reference hydrologic conditions for a given ecoregion. Hydrology did not generally differ between sites with the highest and lowest fish species richness, indicating that other environmental factors likely limit species richness at sites with reference hydrology.Use of ecological limit functions to make decisions regarding proposed hydrologic regime changes, although commonly presented as a management tool, is not as straightforward or informative as often assumed. We contend that statistical evaluation of the internal wedge structure below limit functions may provide a probabilistic understanding of how aquatic ecology is influenced by altered hydrology and may serve as the basis for evaluating the potential effect of proposed hydrologic changes. Published 2013. This article is a U.S. Government work and is in the public domain in the USA. Ecohydrology published by John Wiley & Sons, Ltd.
One‐Pot Microwave Synthesis of Fluorescent Carbogenic Nanoparticles from Triton X‐100 for Cell Imaging
Authors: Rajendran Ramesh , Sohila Subramaniam , Muralidharan Rajalakshmi , Muthamizhchelvan Chellamuthu , Ponnusamy Suruttaiyaudiyar 
Published: November 2013

AbstractCarbon‐based fluorescent nanoparticles have attracted a lot of attention in the field of bioimaging as a result of their excellent emission properties along with their low toxicity. Fluorescent carbogenic nanoparticles (CNPs) were synthesized by a one‐pot microwave pyrolysis technique by using Triton X‐100 as a carbon source. The CNPs are spherical in shape with an average diameter of 5.5 nm, as characterized by transmission electron microscopy and atomic force microscopy. The as‐synthesized CNPs showed strong blue emission under UV illumination, excitation‐dependent emission properties, and chemical stability under different pH conditions. The graphitic nature of the CNPs was studied by using Raman and X‐ray photoelectron spectroscopy. Moreover, the toxicity of these particles was studied through an MTT assay, which showed no noticeable toxicity. The results suggest that the CNPs can be used as effective fluorescent probes for cellular imaging applications.
Reactivity of Diimido Complexes of Moybdenum and Tungsten towards Lithium Derivatives of Diphosphanes and Triphosphanes
Authors: Grubba Rafał , Wiśniewska Aleksandra , Ponikiewski Łukasz , Caporali Maria , Peruzzini Maurizio , Pikies Jerzy 
Published: November 2013

AbstractThe reaction of R2P–P(SiMe3)Li (R = tBu, iPr) with the diimido molybdenum complex [(ArN)2MoCl2·dme] (Ar = 2,6‐iPr2C6H3; dme = 1,2‐dimethoxyethane) yielded the side‐on‐coordinated phosphanylphosphinidene anionic complexes [(2,6‐iPr2C6H3N)2Mo(Cl)(η2‐P=PR2)]– (7Mo, 8Mo). The thermal decomposition of [(2,6‐iPr2C6H3N)2M(Cl)(η2‐P=PR2)]– [M = Mo (7Mo), W (8W)] to [(2,6‐iPr2C6H3N)2M(Cl)(1,2‐η‐tBu2P=P–PtBu2)] [M = Mo (3Mo), W (3W)] was investigated by 31P{1H} NMR spectroscopy. The reactions of [(ArN)2MCl2·dme] (Ar = 2,6‐iPr2C6H3; M = Mo, W) with tBu2P–P(Li)–PtBu2 gave molybdenum and tungsten complexes [(2,6‐iPr2C6H3N)2M(Cl)(1,2‐η‐tBu2P=P–PtBu2)] (3Mo, 3W) bearing an unusual triphosphorus ligand. The solid‐state structures of [(2,6‐iPr2C6H3N)2Mo(Cl)(η2‐P=PtBu2)]– (7Mo), [(2,6‐iPr2C6H3N)2Mo(Cl)(η2‐P=PiPr2)]– (8Mo), [(2,6‐iPr2C6H3N)2Mo(Cl)(1,2‐η‐tBu2P=P–PtBu2)] (3Mo) and [(2,6‐iPr2C6H3N)2W(Cl)(1,2‐η‐tBu2P=P–PtBu2)] (3W) were established by single‐crystal X‐ray diffraction analysis.
A PVC Membrane Sensor for Potentiometric Determination of Atorvastatin in Biological Samples and Pharmaceutical Preparations
Authors: Saber Amr Lotfy 
Published: November 2013

AbstractThe present article reports for the first time the use of Aliquat 336S‐atorvastatin as an electroactive material in a poly(vinyl chloride) matrix membrane sensor plasticized with ortho‐nitrophenyl‐octylether (o‐NPOE) or dioctylphthalate (DOP) for determination of atorvastatin in biological samples (human plasma) and in pharmaceutical preparations. The sensor shows fast, stable and reproducible response over the concentration range of 1.0×10−7–1.0×10−2 mol L−1 atorvastatin with anionic slopes of 60.94±0.2 and 58.22±0.2 and pH range of 5.0–9.0 for o‐NPOE and DOP plasticized based membrane sensors, respectively. The response time of the sensor is stable and fast (10 s). Results were achieved with average recoveries of 99.5 % and 99.3 % and mean standard deviations of ±1.1 % and ±1.4 % for o‐NPOE and DOP plasticized based membrane sensors, respectively. The sensor exhibits high selectivity towards atorvastatin in the presence of many anions, drug excipients and diluents. Validation of the method according to the quality assurance standards shows suitability of the proposed sensors for use in the quality control assessment of the drug.
Passive sampling methods for contaminated sediments: Scientific rationale supporting use of freely dissolved concentrations
Authors: Mayer Philipp , Parkerton Thomas F , Adams Rachel G , Cargill John G , Gan Jay , Gouin Todd , Gschwend Philip M , Hawthorne Steven B , Helm Paul , Witt Gesine , You Jing , Escher Beate I 
Published: November 2013

Abstract
Passive sampling methods (PSMs) allow the quantification of the freely dissolved concentration (Cfree) of an organic contaminant even in complex matrices such as sediments. Cfree is directly related to a contaminant's chemical activity, which drives spontaneous processes including diffusive uptake into benthic organisms and exchange with the overlying water column. Consequently, Cfree provides a more relevant dose metric than total sediment concentration. Recent developments in PSMs have significantly improved our ability to reliably measure even very low levels of Cfree. Application of PSMs in sediments is preferably conducted in the equilibrium regime, where freely dissolved concentrations in the sediment are well-linked to the measured concentration in the sampler via analyte-specific partition ratios. The equilibrium condition can then be assured by measuring a time series or a single time point using passive samplers with different surface to volume ratios. Sampling in the kinetic regime is also possible and generally involves the application of performance reference compounds for the calibration. Based on previous research on hydrophobic organic contaminants, it is concluded that Cfree allows a direct assessment of 1) contaminant exchange and equilibrium status between sediment and overlying water, 2) benthic bioaccumulation, and 3) potential toxicity to benthic organisms. Thus, the use of PSMs to measure Cfree provides an improved basis for the mechanistic understanding of fate and transport processes in sediments and has the potential to significantly improve risk assessment and management of contaminated sediments. Integr Environ Assess Manag 2014;10:197–209. © 2014 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of SETAC.
Key Points
Passive sampling methods (PSMs) can quantify the freely dissolved concentration (Cfree) of a hydrophobic organic contaminant in sediment. Cfree is directly related to chemical activity, which drives diffusive uptake into benthic organisms and exchange across the sediment-water interface. Cfree and chemical activity offer a well-defined basis for the mechanistic understanding of fate and transport processes in sediments and for predicting adverse effects to benthic organisms. Recent developments in PSMs are advancing practical application to improve risk assessment and management of contaminated sediments.
Ultrasound‐assisted fabrication of a biocompatible magnetic hydroxyapatite
Authors: Zhou Gang , Song Wei , Hou Yongzhao , Li Qing , Deng Xuliang , Fan Yubo 
Published: November 2013

AbstractThis work describes the fabrication and characterization of a biocompatible magnetic hydroxyapatite (HA) using an ultrasound‐assisted co‐precipitation method. X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FT‐IR), and transmission electron microscopy (TEM) were used to characterize the structure and chemical composition of the produced samples. The M–H loops of synthesized materials were traced using a vibrating sample magnetometer (VSM) and the biocompatibility was evaluated by cell culture and MTT (3‐(4,5‐dimethylthiazol‐2‐yl)−2,5‐diphenyltetrazolium bromide) assay. Furthermore, in vivo histopathological examinations were used to evaluate the potential toxicological effects of Fe3O4‐HA composites on kidney of SD rats injected intraperitoneally with Fe3O4‐HA particles. The results showed that magnetic iron oxide particles first replace OH ions of HA, which are parallel to the c axis, and then enter the HA crystal lattice which produces changes in the crystal surface of HA. Chemical bond interaction was observed between PO43− groups of HA and iron ions of Fe3O4. The saturation magnetization (MS) of Fe3O4‐HA composites was 46.36 emu/g obtained from VSM data. Cell culture and MTT assays indicated that HA could affect the growth and proliferation of HEK‐293 cells. This Fe3O4‐HA composite produced no negative effects on cell morphology, viability, and proliferation and exhibited remarkable biocompatibility. Moreover, no inflammatory cell infiltration was observed in kidney histopathology slices. Therefore, this study succeeds to develop a Fe3O4‐HA composite as a prospective biomagnetic material for future applications. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 3704–3712, 2014.
Human Variation and Risk Assessment: Microarray and Other Studies Utilizing Human Hepatocytes and Human Liver Subcellular Preparations
Authors: Hodgson Ernest , Wallace Andrew D. , Shah Ruchir R. , Choi Kyoungju , Joo Hyun 
Published: November 2013

ABSTRACTThe new paradigms proposed for human health risk assessment stress the need for the use of human and human‐derived cell lines, and this review summarizes the use of primary human hepatocytes and hepatocyte subcellular preparations for the investigation of the metabolism and metabolic interactions of environmental chemicals. This includes interactions based on inhibition, induction, and activation. The role of cytotoxicity is also considered. The use of hepatocytes and hepatocyte preparations provides especially important information for the investigation of human variation and is summarized. This area is, at present, relatively neglected but will in the future be essential for accurate assessment of human health risk. A detailed summary of an initial attempt to utilize microarray technology for the study of genome‐wide effects is included.
DWI findings of autoimmune pancreatitis: Comparison between symptomatic and asymptomatic patients
Authors: Oki Hodaka , Hayashida Yoshiko , Oki Haruka , Kakeda Shingo , Aoki Takatoshi , Taguchi Masashi , Harada Masaru , Korogi Yukunori 
Published: November 2013

PurposeTo compare the MR findings including diffusion‐weighted imaging (DWI) between symptomatic and asymptomatic patients with autoimmune pancreatitis (AIP) and to determine whether DWI can be used as an objective biomarker for symptomatic AIP, which is considered an indication for steroid therapy.Materials and MethodsThis retrospective study was approved by our institutional review board. MRI scans from 37 patients with AIP (symptomatic, n = 19; asymptomatic, n = 18) were retrospectively evaluated. The imaging studies were performed on a 1.5 Tesla scanner and assessed for parenchymal enlargement, narrowing of the main pancreatic duct, hypointensity on fat‐suppressed T1‐weighted images (FS‐T1WI), a capsule‐like rim, extrapancreatic lesions, and hyperintensity on DWI. The findings were compared by univariate and multivariate logistic regression analysis. Apparent diffusion coefficient (ADC) values were also calculated.ResultsMultivariate analysis showed that hyperintensity on DWI were most significantly associated with the symptoms of AIP (odds ratio = 28.2; P = 0.003). Interobserver agreement for DWI was also high. The ADC values were significantly lower in symptomatic than in asymptomatic patients (0.94 ± 0.17 versus 1.16 ± 0.16 × 10−3 mm2/s, P < 0.001). Receiver operating characteristic curve analysis of the ADC values to differentiate between symptomatic and asymptomatic patients showed that sensitivity was 68.4%, specificity 83.3%, and AUC 0.74.ConclusionSignal intensity on DWI and ADC value were well correlated with the active symptoms of AIP patients. DWI may be useful as an objective biomarker for determining the indication for steroid therapy. J. Magn. Reson. Imaging 2015;41:125–131. © 2013 Wiley Periodicals, Inc.
Implementation of two‐dimensional L‐COSY at 7 tesla: An investigation of reproducibility in human brain
Authors: Verma Gaurav , Hariharan Hari , Nagarajan Rajakumar , Nanga Ravi P.R. , Delikatny Edward J. , Albert Thomas M. , Poptani Harish 
Published: November 2013

PurposeTo evaluate the utility of two‐dimensional (2D) Localized Correlated Spectroscopy (L‐COSY) in metabolic profiling of the human brain at 7 Tesla (T).Materials and MethodsThe 2D L‐COSY sequence was implemented at 7T and its reliability was assessed by test–retest studies of a metabolite phantom and a healthy volunteer. L‐COSY data were acquired from the occipital lobe of healthy subjects (n = 6; all male; age, 30–72 years) to assess intersubject variability. Additionally, two subjects underwent scans from the parieto‐occipital region, basal ganglia, frontal lobe or dorsolateral prefrontal cortex to test the versatility of L‐COSY in studying differing anatomy. Integral/volume measurements of L‐COSY spectra were used to estimate normalized metabolite‐to‐creatine concentrations.ResultsPhantom test–retest studies revealed coefficients of variation (CVs) of 3–20% for most metabolites. Human 2D L‐COSY spectra permitted detection of several metabolite resonances from multiple locations and inter‐subject variation studies demonstrated CVs of 4–26%. Cross‐peaks from gamma‐aminobutyric acid (GABA), isoleucine (Ile), lysine (Lys) and Ethanolamine (Eth) were quantified, which are not readily resolvable with conventional one‐dimensional (1D) MR spectroscopy.Conclusion2D L‐COSY at 7T demonstrated improved sensitivity in detecting additional metabolites with reliability comparable to established techniques at lower fields, which may aid in the metabolic assessment of diseased states. J. Magn. Reson. Imaging 2014;40:1319–1327. © 2013 Wiley Periodicals, Inc.
Stereoselective Condensation of L‐Lactic Acid in Presence of Heterogeneous Catalysts
Authors: Raase Jennifer Marina , Reichert Karl‐Heinz , Schomäcker Reinhard 
Published: November 2013

SummaryMelt phase condensation of L‐lactic acid with heterogeneous catalysts was performed at 0.5 mbar and 180 °C for 1 to 5 h, aiming at enantiopure products. The products were characterized by DSC, HPLC,1H‐NMR spectroscopy and GPC. Zirconium sulfate tetrahydrate was found to be a suitable catalyst with respect to its selectivity and activity. The activity of this catalyst depends on the calcination conditions. By supporting the catalyst on an acidic material with a very high specific surface area, the catalytic activity can be strongly increased without losing selectivity. Products with nearly 100 mol% L‐lactic acid units were obtained even at high conversion and catalyst concentration.
Stimuli‐Responsive Hydrogels Synthesis using Free Radical and RAFT Polymerization
Authors: Gonçalves Miguel A. D. , Pinto Virgínia D. , Costa Rita A. S. , Dias Rolando C. S. , Hernándes‐Ortiz Julio C. , Costa Mário Rui P. F. N. 
Published: November 2013

SummaryTemperature and pH stimuli‐responsive hydrogel particles were synthesized using inverse‐suspension polymerization in batch stirred reactor. Different water soluble co‐monomers were present in the initial mixture (e.g. N‐isopropylacrylamide and acrylic acid) as well as crosslinkers with different functionalities. Different operating conditions such as polymerization temperature, monomers dilution, neutralization and the initial ratios of co‐monomers and monomers/crosslinker were also tried. Hydrogel particles were produced considering classical free‐radical polymerization (FRP) and also RAFT polymerization. Commercially available RAFT agents 4‐cyano‐4‐phenylcarbonothioylthio‐pentanoic acid (CPA), 2‐(dodecylthiocarbonothioylthio)‐2‐methylpropionic acid (DDMAT) and cyanomethyl dodecyl trithiocarbonate (CDT) were alternatively used. Sampling at different polymerization times allowed the study of the kinetics of polymerization through the analysis by SEC of the soluble phase. A tetra‐detector array with simultaneous detection of refractive index, light scattering, intrinsic viscosity and ultra‐violet signals was used in these studies. Usefulness of in‐line FTIR‐ATR monitoring to study the building process of such networks was also assessed. The performance of hydrogel beads was studied through drug delivery tests triggered by changes in the environmental temperature and pH. This research aims to contribute for the elucidation of the connection between the synthesis conditions, molecular architecture and properties/performance of such advanced materials.
Effect of Six Technical Lignins on Thermo‐Mechanical Properties of Novolac type Phenolic Resins
Authors: Martínez Juan D. , Velásquez Jorge A. 
Published: November 2013

SummaryLignin has been studied as an alternative to phenol in phenolic resins, due to economic and environmental reasons. The possibility of partially replacing phenol in phenol–formaldehyde (PF) resins by different types of lignins and analyze the lignin functional groups influence on the thermo‐mechanical properties of the resins, has been explored. Novolac phenolic resins were prepared with six lignins: five lignins from black liquor of soda pulping bagasse and a commercial ammonium lignosulphonate from pinus taeda (LSA). These lignins have different percentages of functional groups (OH aromatic carbonyls and methoxyl) and polysaccharides. The kinetic study found that modified resins elaborated with lignin LSA exhibit the highest values of activation energy (148.66 and 148.92 kJ mol−1 in models of Flynn‐Wall‐Osawa and Friedman respectively), resulting to be the most stable of modified resins. Finally, this same resin has the highest value of the modulus of elasticity (MOE) of 8.02 GPa, even higher than unmodified phenolic resins. Therefore, LSA lignin, showed the best results in friction phenolic resins, this would imply the stability is within the bio‐polymer and attributable to the linkage between PF and lignin.
Modelling of Spray Polymerisation Processes
Authors: Säckel Winfried , Nieken Ulrich 
Published: November 2013

SummarySpray polymerisation is a technique to carry out polymerisations in a highly efficient manner. As experimental optimisation of process parameters is tedious, simulations of the processes inside a single droplet are desirable. Today's models used in spray polymerisation assume ideal mixing and thus do not resolve the particle state along the radius. In this contribution we derive a single particle model for the case of free radical polymerisation, which spatially resolves the physical and chemical processes. The model allows for predicting inhomogeneity of the polymeric product as a function of drying conditions. The state of the polymer is calculated using the method of moments.
Study of the Segregated Behavior of Anionic Microfluidic Polymerization
Authors: Cortese Bruno , Schulze Simon , de Croon Mart , Hessel Volker , Klemm Elias 
Published: November 2013

SummaryIn order to explain the reasons behind the good performance of a microfluidic reactor for anionic polymerization of a commercial polymer ‐ narrow polydispersity index, PDI, of 1.04 (unpublished results of FP7 COPIRIDE project) ‐ modeling of styrene was selected as test system. A comprehensive model accounting for the changes of all the relevant physical parameters was developed and used to compute the fluid dynamics inside the microreactor. The results show that despite the small characteristic dimension of the system an almost segregated behavior is obtained as a consequence of the reaction. This effect leads to the counterintuitive finding that, despite having a very large residence time distribution in the microreactor, polymers with very low PDIs are obtained in a quality as mentioned above.
Emulsion Polymerization Using Switchable Surfactants: A Route Towards Water Redispersable Latexes
Authors: Su Xin , Fowler Candace , O'Neill Catherine , Pinaud Julien , Kowal Erica , Jessop Philip , Cunningham Michael 
Published: November 2013

SummaryColloidal latexes of polystyrene and poly(methyl methacrylate) have been prepared by emulsion polymerization using amidine‐based switchable surfactants. Particles with sizes ranging from 50 nm to 350 nm were obtained. Destabilization of the latexes requires only air and heat which destabilize the latex by removing CO2 from the system. The resulting micron sized particles can be easily filtered to yield a dry polymer powder and a clear aqueous phase. We have also developed a new benign means of reversibly coagulating anionic latexes by using “switchable water”, an aqueous solution of switchable ionic strength. The addition of CO2 and switchable water to an anionic latex can result in aggregation of the latex. Subsequent removal of CO2 by sparging with air allows the aggregated latex to be redispersed and recovered in its original state.