bluuebunny/crossref_metadata_2025 huggingface dataset:
Crystallization behavior of poly(lactide)/poly(β‐hydroxybutyrate)/talc composites
Authors: Tri Phuong Nguyen , Domenek Sandra , Guinault Alain , Sollogoub Cyrille
Published: February 2013

The morphology and miscibility of commercial poly(lactide) (PLA)/poly(β‐hydroxybutyrate) (PHB, from 5 to 20 wt %) blends prepared by melt extrusion method, were investigated using differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) observations. The results show that for all the studied blend contents, PLA/PHB blends are immiscible. The effects of PHB and talc on the nonisothermal cold crystallization kinetics of PLA were examined using a differential scanning calorimetry (DSC) at different heating rates. PHB acted as a nucleating agent on PLA and the addition of talc to the blend yielded further improvement, since significant increase in the enthalpy peak was observed for samples containing 10 wt % PHB and talc (from 0.5 to 5 phr). The crystallization kinetics were then examined using the Avrami–Jeziorny and Liu–Mo approach. The simultaneous presence of PHB and talc induced a decrease of the crystallization half time. The evolution of activation energies determined with Kissinger's equation suggests that blending with PHB and incorporating talc promote nonisothermal cold crystallization of PLA. The synergistic nucleating effect of PHB and talc was also observed on isothermal crystallization of PLA from the melt. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Effect of the filler structure of carbon nanomaterials on the electrical, thermal, and rheological properties of epoxy composites
Authors: He Zhiping , Zhang Xiaohua , Chen Minghai , Li Min , Gu Yizhuo , Zhang Zuoguang , Li Qingwen
Published: February 2013

Carbon nanotubes (CNTs) and graphene nanosheets (GNSs) were used as fillers in epoxy composites with the aim of increasing the electrical and thermal conductivities of the composites. The filling of pristine CNTs produced the highest electrical conductivity (σ), whereas a high CNT functionalization and the two‐dimensional planar structure of GNSs were promising for improving the thermal conductivity. A combination of CNTs and GNSs exploited the advantages of both. When the CNT fraction was larger than 50 wt %, a higher σ was obtained. When a small amount of functionalized CNTs was added to the GNSs, the thermal conductivity was also increased. The rheological measurements revealed the lowest complex viscosity for the GNS filling and showed the exciting advantages of an easy processing. As a result, the mixed filling also exhibited a much lower viscosity than the pure CNT fillings. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Synthesis of novel antibacterial monomers (UDMQA) and their potential application in dental resin
Authors: Liang Xiaoxu , Huang Qiting , Liu Fang , He Jingwei , Lin Zhengmei
Published: February 2013

To prepare antibacterial dental resin, a series of novel urethane dimethacrylates quaternary ammonium methacrylate monomers (UDMQAs) with different substituted alkyl chain length were synthesized, and their structures were confirmed by FTIR and 1H‐NMR spectra. The obtained UDMQAs were used to replace 2,2‐Bis[4‐(2‐hydroxy‐3‐methacryloyloxypropyl)‐phenyl]propane (Bis‐GMA) totally as base monomers of dental resin and mixed with Tri‐ethyleneglycol dimethacrylate (TEGDMA) at the mass ratio of 50/50. The properties of these prepared resins like antibacterial activity, double bond conversion (DC), polymerization shrinkage, flexural strength (FS), and modulus (FM), water sorption and sol fraction were investigated. The most commonly used dental resin Bis‐GMA/TEGDMA (50wt/50wt) was chosen as a reference. The results showed that UDMQAs could endow dental resin with antibacterial activity. Compared with Bis‐GMA‐based dental resin, UDMQAs‐based resin had the same or higher DC, lower polymerization shrinkage, lower flexural strength and modulus, and higher water sorption and sol fraction. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
‘Role stretch’: assessing the blurring of teaching and non‐teaching in the classroom assistant role in Scotland
Authors: Warhurst Chris , Nickson Dennis , Commander Johanna , Gilbert Kay
Published: February 2013

With the increasing number of teaching and classroom assistants across the UK there is now much debate about what their role should be. In particular concerns have arisen about the extent to which they overstep the boundary from supporting teaching and learning into teaching pupils. This study assesses this issue within Scotland. It draws on a national survey of 2000 head teachers, teachers and classroom assistants and interviews with directors of education in nearly half of all Scottish local authorities. Findings from the research suggest a small number of classroom assistants in Scotland are overstepping the boundary into teaching. The paper concludes with an explanation as to why this is happening taking into account aspects such as local authority policy, school size and the individual characteristics of the classroom assistants.
Reworking practice through an AfL project: an analysis of teachers’ collaborative engagement with new assessment guidelines
Authors: Hermansen Hege , Nerland Monika
Published: February 2013

In recent years, the concept of Assessment for Learning (AfL) has travelled across countries, giving rise to a range of educational policy initiatives and school development projects. While researchers have focused on issues such as how formative assessment can support student learning and lead to more efficient classroom practices, less attention has been paid to the collaborative work required to develop shared assessment practices at the school level, and to the integration of AfL‐related principles and tools in the collective practice. This paper focuses on the challenges emerging for a teacher team engaging with an AfL project in a lower secondary school in Norway. By employing concepts and perspectives from social practice theory, AfL is understood as a problem complex that needs to be explored and developed locally. We have analysed data from seven video‐recorded meetings of an AfL team, supplemented by interviews and field notes, in order to make visible the micro processes of teachers' collaborative work. The analysis shows how the teachers needed to rework historically established practices and principles, which in turn called for a negotiation and re‐contextualisation of new concepts and artefacts in their efforts to develop shared assessment practices. This again required ways of representing existing practices and imagining future scenarios. Based on these observations we recommend that AfL projects be understood in their wider curricular, institutional, and social contexts, and that the constructive dimensions of teachers' collaborative work in such projects should be acknowledged.
The politics of languages in education: issues of access, social participation and inequality in the multilingual context of Pakistan
Authors: Tamim Tayyaba
Published: February 2013

This paper, based on some findings of a wider three‐year study, sets forth the issue of languages used and taught in education as a dimension of inequality and highlights its implications for widening participation and access in the multilingual context of Pakistan. The paper takes secondary education in private and government schools in Pakistan as a point of departure, and through themes that emerge from a qualitative multiple‐case studies account of 32 participants (final year graduating students and their same‐sex five‐ to six‐years older siblings) explores issues of inequality with reference to Amertya Sen's capability approach and Pierre Bourdieu's social critical theory. The findings revealed that the concurrent processes of (a) hegemony of English; (b) its discriminatory distribution through schooling; and (c) devaluation of local languages, led by the language policy and mediated through educational institutions, diminished the transformative impact of education in expanding opportunities for widening participation and access. Issues of inequality continue to haunt the underprivileged despite their secondary education. The paper highlights the importance of considering the political economy of languages chosen and taught in formal education as a means of evaluating social justice in educational contexts and considering languages in education decisions with reference to national language policy.
Isostructural unbranched alkyl‐chains as tools for stabilizing β‐turn structure
Authors: Kaur Rajwant , Kishore Raghuvansh
Published: February 2013

To investigate the structural role played by isostructural unbranched alkyl‐chains on the conformational ensemble and stability of β‐turn structures, the conformational properties of a designed model peptide: Plm‐Pro‐Gly‐Pda (1, Plm: H3C—(CH2)14—CONH—; Pda: —CONH— (CH2)14—CH3) have been examined and compared with the parent peptide: Boc‐Pro‐Gly‐NHMe (2, Boc: tert‐butoxycarbonyl; NHMe: N‐methylamide). The characteristic 13C NMR chemical‐shifts of the Pro Cβ and Cγ resonances ascertained the incidence of an all‐trans peptide‐bond in low polarity deuterochloroform solution. Using FTIR and 1H NMR spectroscopy, we establish that apolar alkyl‐chains flanking a β‐turn promoting Pro‐Gly sequence impart definite incremental stability to the well‐defined hydrogen‐bonded structure. The assessment of 1H NMR derived thermodynamic parameters of the hydrogen‐bonded amide‐NHs via variable temperature indicate that much weaker hydrophobic interactions do contribute to the stability of folded reverse turn structures. The far‐UV CD spectral patterns of 1 and 2 in 2,2,2‐trifluoroethanol are consistent with Pro‐Gly specific type II β‐turn structure, concomitantly substantiate that the flanking alkyl‐chains induce substantial bias in enhanced β‐turn populations. In view of structural as well as functional importance of the Pro‐Gly mediated secondary structures, besides biochemical and biological significance of proteins lipidation via myristoylation or palmytoilation, we highlight potential convenience of the unbranched Plm and Pda moieities not only as main‐chain N‐ and C‐terminal protecting groups but also to mimic and stabilize specific isolated secondary and supersecondary structural components frequently observed in proteins and polypeptides. © 2013 Wiley Periodicals, Inc. Biopolymers 99: 419–426, 2013.
Development of a new UPLC‐MSMS method for the determination of temozolomide in mice: application to plasma pharmacokinetics and brain distribution study
Authors: Goldwirt Lauriane , Zahr Noel , Farinotti Robert , Fernandez Christine
Published: February 2013

A sensitive and accurate liquid chromatography method with mass spectrometry detection was developed and validated for the quantification of temozolomide in mouse plasma and brain. Theophyllin was used as the internal standard. A single‐step protein precipitation was used for plasma and brain sample preparation. The method was validated with respect to selectivity, extraction recovery, linearity, intra‐ and inter‐day precision and accuracy, limit of quantification and stability. The method has a limit of quantification of 50 ng/mL for temozolomide in plasma and 125 ng/g in brain. This method was used successfully to perform brain and plasma pharmacokinetic studies of temozolomide in mice after intraperitoneal administration. Copyright © 2013 John Wiley & Sons, Ltd.
Is there a role for immune checkpoint blockade with ipilimumab in prostate cancer?
Authors: Cha Edward , Small Eric J.
Published: February 2013

Treatment for advanced prostate cancer has and will continue to grow increasingly complex, owing to the introduction of multiple new therapeutic approaches with the potential to substantially improve outcomes for this disease. Agents that modulate the patient's immune system to fight prostate cancer – immunotherapeutics – are among the most exciting of these new approaches. The addition of antigen‐specific immunotherapy to the treatment of castration‐resistant prostate cancer (CRPC) has paved the way for additional research that seeks to augment the activity of the immune system itself. The monoclonal antibody ipilimumab, approved in over 40 countries to treat advanced melanoma and currently under phase 2 and 3 investigation in prostate cancer, is thought to act by augmenting immune responses to tumors through blockade of cytotoxic T‐lymphocyte antigen 4, an inhibitory immune checkpoint molecule. Ipilimumab has been studied in seven phase 1 and 2 clinical trials that evaluated various doses, schedules, and combinations across the spectrum of patients with advanced prostate cancer. The CRPC studies of ipilimumab to date suggest that the agent is active in prostate cancer as monotherapy or in combination with radiotherapy, docetaxel, or other immunotherapeutics, and that the adverse event profile is as expected given the safety data in advanced melanoma. The ongoing phase 3 program will further characterize the risk/benefit profile of ipilimumab in chemotherapy‐naïve and ‐pretreated CRPC.
When food is more than nutrition: Understanding emotional eating and overconsumption
Authors: Kemp Elyria , Bui My , Grier Sonya
Published: February 2013

This research examines how more proximal or immediate goals of affect regulation impact goals of weight loss and maintenance. Findings suggest that both psychological and social factors play a role in eating behavior and food overconsumption. Specifically, the narratives of self‐identified emotional eaters reveal that negative emotion, prefactual thinking, and ruminative propensities play major roles in contributing to food‐related consumption. Additionally, emotional eating informants' consumption behavior is greatly impacted by the attitudes and behaviors of others. Several approaches for developing interventions for emotional eaters and furthering transformative research in obesity and overconsumption are discussed.

Copyright © 2013 John Wiley & Sons, Ltd.
Fluorescent Probes for G‐Quadruplex Structures
Authors: Vummidi Balayeshwanth R. , Alzeer Jawad , Luedtke Nathan W.
Published: February 2013

Mounting evidence supports the presence of biologically relevant G‐quadruplexes in single‐cell organisms, but the existence of endogenous G‐quadruplex structures in mammalian cells remains highly controversial. This is due, in part, to the common misconception that DNA and RNA molecules are passive information carriers with relatively little structural or functional complexity. For those working in the field, however, the lack of available tools for characterizing DNA structures in vivo remains a major limitation to addressing fundamental questions about structure–function relationships of nucleic acids. In this review, we present progress towards the direct detection of G‐quadruplex structures by using small molecules and modified oligonucleotides as fluorescent probes. While most development has focused on cell‐permeable probes that selectively bind to G‐quadruplex structures with high affinity, these same probes can induce G‐quadruplex folding, thereby making the native conformation of the DNA or RNA molecule (i.e., in the absence of probe) uncertain. For this reason, modified oligonucleotides and fluorescent base analogues that serve as “internal” fluorescent probes are presented as an orthogonal means for detecting conformational changes, without necessarily perturbing the equilibria between G‐quadruplex, single‐stranded, and duplex DNA. The major challenges and motivation for the development of fluorescent probes for G‐quadruplex structures are presented, along with a summary of the key photophysical, biophysical, and biological properties of reported examples.
Partitioning of Fluoroquinolones on Wastewater Sludge
Authors: Zhou Xuefei , Zhang Yalei , Shi Lu , Chen Jiabin , Qiang Zhimin , Zhang Tian C.
Published: February 2013

Laboratory‐scale batch experiments were conducted to investigate the adsorption behavior of eight fluoroquinolones (FQs) on aerobic, anoxic, and anaerobic sludge, under different adsorpiton time, pH, and temperature conditions. Results indicated that adsorption of FQs onto all sludge was a physical sorption process. The relationship of the partitioning coefficient (Kd) and the octanol/water partition coefficient (Kow) for each FQ was established. The adsorbed fraction of FQs on sludge could then be predicted with the Kd. It was calculated that about 50–72% of the FQs were adsorbed on the sludge. Therefore, the adsorption effect must be considered when studying the fate and occurrence of FQs in wastewater treatment systems.
L‐band surface‐coil resonator with voltage‐control impedance‐matching for EPR tooth dosimetry
Authors: Haga Tadatsugu , Hirata Hiroshi , Lesniewski Piotr , Rychert Kevin M. , Williams Benjamin B. , Flood ANN B. , Swartz Harold M.
Published: February 2013

A surface‐coil resonator that is capable of voltage‐control for impedance‐matching is described in the context of its application in electron paramagnetic resonance (EPR)‐based tooth dosimetry. Varactor‐based coupling of an 1,150 MHz surface‐coil resonator was achieved to supply RF power. The developed resonator consists of a single‐turn loop, 9 mm in mean diameter; a capacitor made of a polytetrafluoroethylene (PTFE) substrate; a quarter‐wavelength parallel transmission line; a half‐wave line balun, and varactors. The surface coil and the PTFE substrate capacitor were connected to a quarter‐wavelength parallel transmission line. For the newly developed resonator, an RF magnetic field‐generation efficiency of 130 μT/W1/2 was achieved, and the sensitivity of the surface‐coil resonator was investigated with an irradiated tooth. Measurements consisting of six sets of EPR spectra on a 10 Gy irradiated tooth using this newly developed resonator achieved a standard error of the mean (SEM) of 1.1 Gy. This level of accuracy of dose measurements was comparable to the SEM with a previously developed resonator; however, the previous resonator was not capable of voltage‐control for impedance‐matching adjustment, which represents a significant advance in facilitating automation. © 2013 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 43B:32–40, 2013
Effects of different field strengths, gradient directions, and acquisitions on fractional anisotropy in diffusion tensor imaging: A tract‐based spatial statistics study
Authors: Seo Youngseob
Published: February 2013

The effects of increasing acquisitions and gradient directions on fractional anisotropy (FA) at 1.5T versus 3T were investigated using an operator‐independent methodology (tract‐based spatial statistics) by minimizing technical differences in image acquisition between the two magnetic resonance imaging platforms and also FA values at roughly equivalent signal‐to‐noise ratio and data acquisition time were compared. Five healthy subjects underwent this experiment. Diffusion tensor imaging (DTI) was performed at 1.5T and 3T. Gradient schemes were 6, 30, and 96 directions. The numbers of acquisitions were 5, 10, and 15 for 6‐direction; 1, 2, and 3 acquisitions for 30‐direction; and 1 acquisition for 96‐direction scheme. FA values in the callosal genu (CG), callosal splenium (CS), posterior limb of the internal capsule (PLIC), and the superior longitudinal fasciculus (SLF) bilaterally were assessed. For 6‐direction scheme at 5 acquisitions, FA values were higher at 1.5T than at 3T. FA values derived using 30‐direction scheme were higher at 3T than 1.5T in the left SLF and PLIC bilaterally. In the CG and CS, FA values at equivalent signal‐to‐noise ratio derived from different acquisitions and gradient directions differed by <7.6%. In the right PLIC and left SLF, FA values measured for 6‐direction scheme differed from 30‐direction scheme by >11% at 1.5T. DTI data acquired at 3T are not always comparable to that at 1.5T. The center of the brain does not appear to be affected but the peripheral white matter appears to be affected by field strengths, number of acquisitions, and gradient directions. © 2013 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 43B:41–48, 2013
Universality for the Focusing Nonlinear Schrödinger Equation at the Gradient Catastrophe Point: Rational Breathers and Poles of the Tritronquée Solution to Painlevé I
Authors: Bertola Marco , Tovbis Alexander
Published: February 2013

The semiclassical (zero‐dispersion) limit of solutions $q=q(x,t,\epsilon)$ to the one‐dimensional focusing nonlinear Schrödinger equation (NLS) is studied in a scaling neighborhood D of a point of gradient catastrophe ($x_0,t_0$). We consider a class of solutions, specified in the text, that decay as $|x| \rightarrow \infty$. The neighborhood D contains the region of modulated plane wave (with rapid phase oscillations), as well as the region of fast‐amplitude oscillations (spikes). In this paper we establish the following universal behaviors of the NLS solutions q near the point of gradient catastrophe: (i) each spike has height $3|q{_0}(x_0,t_0)|$ and uniform shape of the rational breather solution to the NLS, scaled to the size ${\cal O}(\epsilon)$; (ii) the location of the spikes is determined by the poles of the tritronquée solution of the Painlevé I (P1) equation through an explicit map between D and a region of the Painlevé independent variable; (iii) if $(x,t)\in D$ but lies away from the spikes, the asymptotics of the NLS solution $q(x,t, \epsilon)$ is given by the plane wave approximation $q_0(x,t, \epsilon)$, with the correction term being expressed in terms of the tritronquée solution of P1. The relation with the conjecture of Dubrovin, Grava, and Klein about the behavior of solutions to the focusing NLS near a point of gradient catastrophe is discussed. We conjecture that the P1 hierarchy occurs at higher degenerate catastrophe points and that the amplitudes of the spikes are odd multiples of the amplitude at the corresponding catastrophe point. Our technique is based on the nonlinear steepest‐descent method for matrix Riemann‐Hilbert problems and discrete Schlesinger isomonodromic transformations. © 2013 Wiley Periodicals, Inc.
Liposomal Amphotericin B for the Treatment of Cryptococcal Meningitis in HIV/AIDS Patients in India—A Pilot Pharmacokinetic Study
Authors: Jadhav Manoj , Jadhav Priyanka , Shinde Vishal , Kadam Prashant , Kshirsagar Nilima
Published: February 2013

The liposomal formulation of amphotericin B greatly reduces side effects like nephrotoxicity. The present pilot study describes the pharmacokinetic characteristics of liposomal Amp B given to eight patients of cryptococcal meningitis with HIV/AIDS at a dose of 1 and 3 mg/kg/day. We observed that the pharmacokinetic parameters namely AUC, Cmax, CL, Vd, and half‐life were not proportionate with 1 and 3 mg/kg/day dose of Fungiosme™. With 1 and 3 mg/kg/day dose the mean Cmax was found to be 626.54 ± 39.26 and 1049.90 ± 742.75 ng/mL, respectively. In conclusion, liposomal Amp B was observed to be safe and efficacious in the treatment of cryptococcal meningitis in HIV/AIDS patients, however, a pharmacokinetics study with larger cohort of patients of cryptococcal meningitis in HIV AIDS is warranted.
Diversification and senescence of Foxp3+ regulatory T cells during experimental autoimmune encephalomyelitis
Authors: Tauro Sharyn , Nguyen Phuong , Li Bofeng , Geiger Terrence L.
Published: February 2013

The fate of Foxp3+ regulatory T (Treg) cells responding during autoimmunity is not well defined. We observed a marked elevation in KLRG1+ (where KLRG1 stands for killer cell lectin‐like receptor G1) CNS‐infiltrating Treg cells in experimental autoimmune encephalomyelitis (EAE), and assessed their origin and properties. KLRG1+ Treg cells showed increased activation marker expression, Foxp3 and CD25 levels, and more rapid cell cycling than KLRG1− cells. KLRG1− Treg cells converted into KLRG1+ cells and this was increased in autoimmune inflammation. Conversion was unidirectional; KLRG1+ Treg cells did not revert to a KLRG1− state. KLRG1+ but notKLRG1−Treg cells survived poorly, indicative of terminal differentiation. This was associated with diminished BCL2 and increased apoptosis of isolated cells. KLRG1 was also upregulated on iTreg cells after transfer and EAE induction or on iTreg cells developing spontaneously during EAE. KLRG1+ Treg cells produced more IL‐10 and had altered effector cytokine production compared with their KLRG1− counterparts. Despite their differences, KLRG1+ and KLRG1− Treg cells proved similarly potent in suppressing EAE. KLRG1+ and KLRG1− populations were phenotypically heterogeneous, with the extent and pattern of activation marker expression dependent both on cellular location and inflammation. Our results support an extensive diversification of Treg cells during EAE, and associate KLRG1 with altered Treg‐cell function and senescence.
Bayesian inference about odds ratio structure in ordinal contingency tables
Authors: Kateri M. , Agresti A.
Published: February 2013

When the goal of a study is to compare two groups on an ordinal categorical scale, a large number of inferential methods are available. Most methods are designed to detect a location effect, such as by focusing a single‐degree‐of‐freedom test on an effect parameter. Often, rather than merely summarizing by aP‐value to describe the evidence against a null hypothesis, it is of interest to consider whether a stronger conclusion can be made. For example, can we conclude that the population distributions are stochastically ordered? For parameter space regions described by order restrictions, frequentist methods are not well designed for significance testing. For example, a frequentistP‐value for testing identical distributions against an alternative of stochastically ordered distributions can be very small even when the sample distributions give clear evidence that the distributions do not have the ordering property. The Bayesian approach seems better equipped to handle such questions. We discuss this in the context of stochastic ordering and other types of ordinal odds ratio structure, for the two‐group comparison and for more general contexts. For Dirichlet priors, simple simulations provide posterior probabilities of particular ordinal odds ratio structures. Copyright © 2013 John Wiley & Sons, Ltd.
Probing the deep critical zone beneath the Luquillo Experimental Forest, Puerto Rico
Authors: Buss H. L. , Brantley S. L. , Scatena F. N. , Bazilievskaya E. A. , Blum A. , Schulz M. , Jiménez R. , White A. F. , Rother G. , Cole D.
Published: February 2013

Recent work has suggested that weathering processes occurring in the subsurface produce the majority of silicate weathering products discharged to the world's oceans, thereby exerting a primary control on global temperature via the well‐known positive feedback between silicate weathering and CO2. In addition, chemical and physical weathering processes deep within the critical zone create aquifers and control groundwater chemistry, watershed geometry and regolith formation rates. Despite this, most weathering studies are restricted to the shallow critical zone (e.g. soils, outcrops). Here we investigate the chemical weathering, fracturing and geomorphology of the deep critical zone in the Bisley watershed in the Luquillo Critical Zone Observatory, Puerto Rico, from two boreholes drilled to 37.2 and 27.0 m depth, from which continuous core samples were taken. Corestones exposed aboveground were also sampled. Weathered rinds developed on exposed corestones and along fracture surfaces on subsurface rocks slough off of exposed corestones once rinds attain a thickness up to ~1 cm, preventing the corestones from rounding due to diffusion limitation. Such corestones at the land surface are assumed to be what remains after exhumation of similar, fractured bedrock pieces that were observed in the drilled cores between thick layers of regolith. Some of these subsurface corestones are massive and others are highly fractured, whereas aboveground corestones are generally massive with little to no apparent fracturing. Subsurface corestones are larger and less fractured in the borehole drilled on a road where it crosses a ridge compared with the borehole drilled where the road crosses the stream channel. Both borehole profiles indicate that the weathering zone extends to well below the stream channel in this upland catchment; hence weathering depth is not controlled by the stream level within the catchment and not all of the water in the watershed is discharged to the stream. Copyright © 2013 John Wiley & Sons, Ltd.
Unraveling a municipal effluent's toxicity to Tripneustes gratilla sperm fertilization
Authors: Vazquez Lourdes C.
Published: February 2013

A tiered investigative approach was employed to characterize and identify substances responsible for the persistent toxicity of a primary-treated municipal effluent to gametes of the Hawaiian sea urchin, Tripneustes gratilla. Toxicity identification evaluation (TIE) procedures from the US Environmental Protection Agency were modified to account for the tolerance of T. gratilla gametes to various sample manipulations. Microtox rapid toxicity screening was applied in some aspects of the study after verifying a correlation between the pattern of toxic responses of T. gratilla gametes and that of the bioluminescent bacteria Vibrio fischeri. Toxicity identification evaluation phase I manipulations revealed a toxicity profile implicating surfactants as possible toxicants, and TIE phase II toxicity assessment of isolated fractions coupled with colorimetric surfactant analyses confirmed the possible role of surfactants in effluent toxicity. The toxic effects of standard reference surfactants on T. gratilla fertilization indicated a concordance with the effects of the more nonpolar effluent fractions. Treatability studies showed that biodegradation by activated sludge eliminated effluent toxicity to urchin gametes. Environ Toxicol Chem 2013;32:1382–1387. © 2013 SETAC
Risk assessment using the species sensitivity distribution method: Data quality versus data quantity
Authors: Dowse Renee , Tang Doudou , Palmer Carolyn G. , Kefford Ben J.
Published: February 2013

Species sensitivity distributions (SSDs) are cumulative distributions of measures of species sensitivity to a stressor or toxicant, and are used to estimate concentrations that will protect p% of a community (PCp). There is conflict between the desire to use high-quality sensitivity data in SSDs, and to construct them with a large number of species forming a representative sample. Trade-offs between data quality and quantity were investigated using the effects of increasing salinity on the macroinvertebrate community from the Hunter River catchment, in eastern Australia. Five SSDs were constructed, representing five points along a continuum of data quality versus data quantity and representativeness. This continuum was achieved by the various inclusion/exclusion of censored data, nonmodeled data, and extrapolation from related species. Protective concentrations were estimated using the Burr type III distribution, Kaplan-Meier survival function, and two Bayesian statistical models. The dominant taxonomic group was the prime determinant of protective concentrations, with an increase in PC95 values resulting from a decrease in the proportion of Ephemeropteran species included in the SSD. In addition, decreases in data quantity in a SSD decreased community representativeness. The authors suggest, at least for salinity, that the inclusion of right censored data provides a more representative sample of species that reflects the natural biotic assemblage of an area to be protected, and will therefore improve risk assessment. Environ Toxicol Chem 2013;32:1360–1369. © 2013 SETAC
Toxicological implications of microcystins for zebrafish embryos in the presence of other environmental pollutants
Authors: Pavagadhi Shruti , Gong Zhiyuan , Balasubramanian Rajasekhar
Published: February 2013

Microcystins (MCs) interact with environmental contaminants as well as various other congeners of the MC family in the natural environment and with antioxidants in the exposed organisms. These interactions are likely to modify the toxicological behavior of MCs at the cellular level. The present study was conducted to determine the toxicological response of extracellular MCs in aquatic systems under environmentally relevant conditions. Microcystin–leucine–arginine (MCLR) and microcystin–arginine–arginine (MCRR) were introduced at different concentrations in a single-component (MCLR or MCRR) or dual-component (MCLR and MCRR) system to zebrafish embryos in the presence of inorganic elements (Hg, As, Pb, and Cd) and nutrient species (NO3−, PO43−, and Cl−1). Hatchability, heart rate, and mortality of zerbrafish embryos were monitored together with changes in the activity of glutathione-S-transferase (GST) to evaluate their response on exposure to MCLR and MCRR. There was a significant reduction in all these parameters at higher doses of MCLR and MCRR (>100 ng/mL), implying bioaccumulation of these MCs in embryos and adverse effects on early development stages of the fish. It was further observed that PO43−and Cl− enhanced the toxic effects of MCLR and MCRR while NO3− attenuated their toxic effects. In contrast, all 4 toxic elements together increased the toxicity of MCLR and MCRR to embryos compared with their single-component counterparts. Thus, the toxic effects of MCs depend not only on their relative environmental concentrations, but also on those of other environmental pollutants and the levels of antioxidants in exposed organisms. Environ Toxicol Chem 2013;32:1574–1581. © 2013 SETAC
Mathematical relationships between metrics of chemical bioaccumulation in fish
Authors: Mackay Don , Arnot Jon A. , Gobas Frank A.P.C. , Powell David E.
Published: February 2013

Five widely used metrics of bioaccumulation in fish are defined and discussed, namely the octanol–water partition coefficient (KOW), bioconcentration factor (BCF), bioaccumulation factor (BAF), biomagnification factor (BMF), and trophic magnification factor (TMF). Algebraic relationships between these metrics are developed and discussed using conventional expressions for chemical uptake from water and food and first-order losses by respiration, egestion, biotransformation, and growth dilution. Two BCFs may be defined, namely as an equilibrium partition coefficient KFW or as a nonequilibrium BCFK in which egestion losses are included. Bioaccumulation factors are shown to be the product of the BCFK and a novel equilibrium multiplier M containing 2 ratios, namely, the diet-to-water concentration ratio and the ratio of uptake rate constants for respiration and dietary uptake. Biomagnification factors are shown to be proportional to the lipid-normalized ratio of the predator/prey values of BCFK and the ratio of the equilibrium multipliers. Relationships with TMFs are also discussed. The effects of chemical hydrophobicity, biotransformation, and growth are evaluated by applying the relationships to a range of illustrative chemicals of varying KOW in a linear 4-trophic-level food web with typical values for uptake and loss rate constants. The roles of respiratory and dietary intakes are demonstrated, and even slow rates of biotransformation and growth can significantly affect bioaccumulation. The BCFKs and the values of M can be regarded as the fundamental determinants of bioaccumulation and biomagnification in aquatic food webs. Analyzing data from food webs can be enhanced by plotting logarithmic lipid-normalized concentrations or fugacities as a linear function of trophic level to deduce TMFs. Implications for determining bioaccumulation by laboratory tests for regulatory purposes are discussed. Environ Toxicol Chem 2013;32:1459–1466. © 2013 SETAC
A multivariate analysis approach to the study of chemical and functional properties of chemo‐diverse plant derivatives: lavender essential oils
Authors: Maietti Silvia , Rossi Damiano , Guerrini Alessandra , Useli Chiara , Romagnoli Carlo , Poli Ferruccio , Bruni Renato , Sacchetti Gianni
Published: February 2013

Six lavender essential oils, L. angustifolia and five Lavandula x hybrida cultivars (Super Z, Abrialis, R.C., Alardii and Ordinario), were evaluated from a phytochemical and biological standpoint, and the results were computed by using multivariate data analysis. The essential oils were analysed by gas chromatography, gas chromatography–mass spectrometry and headspace gas‐chromatography. Multivariate analyses (principal component analysis) identified three main phytochemical clusters among lavender essential oils, represented by 1,8‐cineole, linalyl acetate and linalool. Functional properties of the essential oils were checked by (1) estimating cytotoxicity and genotoxicity using the Saccharomyces cerevisiae D7 strain; (2) determining antifungal activity against three common phytopathogens (Pythium ultimum, Magnaporthe grisea and Botrytis cinerea), by performing an agar vapour bioassay; and (3) calculating the antioxidant capacity by using the 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) and β‐carotene bleaching tests. No mutagenic effects were detected, but multivariate analyses (PLS, partial least squares regression) showed that the essential oils belonging to the linalool cluster were the most cytotoxic. Antifungal activity against phytopathogens confirmed the predictive results of PLS. The differences among lavender essential oils regarding weak antioxidant capacity showed a positive relationship between the high polarity compounds and the DPPH method, as determined by PLS. The opposite effect was shown for the same type of compound and β‐carotene. Ketones and esters did not exert any significant antioxidant activity. In conclusion, taking lavender essential oils as a model and computing multivariate data of a reduced number of parameters, the proposed approach assured the description of the relationship between a phytocomplex, its constituents and bioactivities, and allowed a comprehensive, predictive approach to be defined, for which the chemical profile provides a possible synergic overall effort in terms of applicative perspectives. Copyright © 2013 John Wiley & Sons, Ltd.
Review:In vitrobiofilm models for studying oral malodour
Authors: Greenman John , Saad Saliha , Hewett Keith , Thorn Robin M. S. , Reynolds Darren M.
Published: February 2013

Most cases of oral malodour are thought to be due to microbial biofilms that form in the pits and fissures that exist on the dorsum of the tongue. The tongue microflora is mainly fed by saliva, but nutrient sources could also include exfoliated mammalian cells and tissue fluid (e.g. crevicular fluid) which may bring high concentrations of sulfur‐containing substrates. In addition, consumed food could also contribute nutrients to a lesser degree. The collective microbial biofilm metabolism breaks down proteins, peptides and glycoproteins into cell transportable monomers, including sugars and amino acids. A significant portion of the biofilm can convert nutrient substrates into volatile organic compounds (VOCs), including odiferous volatile sulfur compounds (VSCs). A number ofin vitrobiofilm models have been developed to study the generation and inhibition of microbial oral malodour. Dynamic steady‐state models coupled with real‐time monitoring of VOCs seems to offer advantages over models based on batch sampling from batch culture. Copyright © 2013 John Wiley & Sons, Ltd.
The Effect of Adding Ce1–xSmxO2–x/2 with Different Sm Contents on the Electrochemical Performance of GdBaCo2O5+δ Based Composite Cathode
Authors: Li N. , Lü Z. , Wei B. , Huang X. Q. , Zhang Y. H. , Zhu X. B. , Su W. H.
Published: February 2013

In this paper, the Ce1–xSmxO2–x/2 (x = 0.025, 0.05, 0.1, 0.2) samples were synthesized and then mixed with GdBaCo2O5+δ (GBCO) to form GBCO–Ce1–xSmxO2–x/2 composite cathodes. The electrochemical performance of the composite cathodes was investigated by the electrochemical impedance spectroscopy (EIS) as a function of temperature and oxygen partial pressure. The impedance spectra results demonstrated that the introduction of proper Ce1–xSmxO2–x/2 phase remarkably enhanced the electrochemical performance of GBCO cathode and caused a reduction in the total polarization resistance (Rp). Furthermore, as the amount of Ce1–xSmxO2–x/2 in composite cathode was fixed, the variation of Sm content in Ce1–xSmxO2–x/2 also had a significant influence on the electrochemical performance of the GBCO–Ce1–xSmxO2–x/2 cathodes. For example, the Rp of GBCO cathodes containing 10 wt.% Ce1–xSmxO2–x/2 considerably reduced from 0.37 to 0.17 Ω cm2 at 600 °C with the decreasing Sm content x from 0.2 to 0.025. The improvement in performance of the GBCO–Ce1–xSmxO2–x/2 cathodes compared to pure GBCO cathode could be mainly attributed to the catalytic activity of Ce1–xSmxO2–x/2 towards the surface diffusion related processes, which was an elementary step in oxygen reduction reaction at cathode.
Bid–Ask Spreads and Implied Volatilities of Key Players in a FX Options Market
Authors: Galai Dan , Schreiber Ben Z.
Published: February 2013

This study proposes a simultaneous estimation of the bid–ask spreads (BAS) and implied volatility (IV), based on trading options of various key players in the Israeli OTC FX options market. It explores the surface shape of both variables based on a “clientele effect.” We employ detailed data on OTC foreign exchange options trading that enable us to examine the behavior of the key players (financial companies, non‐financial firms, households, and foreign investors) during relatively turbulent and tranquil periods. Using simultaneous unbiased estimates of BAS and IV, we find substantial differences in BASs among key players while insignificant differences in IV. This evidence reflects differences in key players' profile such as trading size, sophistication and contestability on one hand and a “no arbitrage opportunities” of IV on the other hand. © 2013 Wiley Periodicals, Inc. Jrl Fut Mark
Frequency‐dependent landscape response to climatic forcing
Authors: Godard Vincent , Tucker Gregory E. , Burch Fisher G. , Burbank Douglas W. , Bookhagen Bodo
Published: February 2013

Whereas the existence of pronounced orbitally controlled periodicities is a major feature of Earth climate, its impact on landscape dynamics remains poorly understood. We use a Landscape Evolution Model (LEM) to systematically investigate the response of landscapes to a range of periodic oscillations in precipitation. The resulting sediment‐flux evolution displays a pronounced sensitivity to the period of the input precipitation signal, such that, for a given erodibility, a specific periodicity maximizes the amplitude of the response. This optimal period of “resonance” scales as the inverse of the erodibility, but is progressively filtered out of the response when the intensity of hillslope diffusion increases. This frequency‐dependent landscape behavior displayed by our model provides a mechanistic perspective on Molnar's (2004) proposition that ubiquitous changes in Late Cenozoic continental denudation could result directly from modifications in the spectral content of the climatic signal.
Recent anthropogenic increases in SO2from Asia have minimal impact on stratospheric aerosol
Authors: Neely R. R. , Toon O. B. , Solomon S. , Vernier J.‐P. , Alvarez C. , English J. M. , Rosenlof K. H. , Mills M. J. , Bardeen C. G. , Daniel J. S. , Thayer J. P.
Published: February 2013

Observations suggest that the optical depth of the stratospheric aerosol layer between 20 and 30 km has increased 4–10% per year since 2000, which is significant for Earth's climate. Contributions to this increase both from moderate volcanic eruptions and from enhanced coal burning in Asia have been suggested. Current observations are insufficient to attribute the contribution of the different sources. Here we use a global climate model coupled to an aerosol microphysical model to partition the contribution of each. We employ model runs that include the increases in anthropogenic sulfur dioxide (SO2) over Asia and the moderate volcanic explosive injections of SO2observed from 2000 to 2010. Comparison of the model results to observations reveals that moderate volcanic eruptions, rather than anthropogenic influences, are the primary source of the observed increases in stratospheric aerosol.
The 1970's shift in ENSO dynamics: A linear inverse model perspective
Authors: Aiken Christopher M. , Santoso Agus , McGregor Shayne , England Matthew H.
Published: February 2013

Inverse methods are used to investigate whether the observed changes in El Niño–Southern Oscillation (ENSO) character since the 1970's climate shift are consistent with a change in the linear ENSO dynamics. Linear Inverse Models (LIMs) are constructed from tropical sea surface temperature (SST), thermocline depth, and zonal wind stress anomalies from the periods 1958–1977 and 1978–1997. Each LIM possesses a single eigenmode that strongly resembles the observed ENSO in frequency and phase propagation character over the respective periods. Extended stochastically forced simulations using these and the LIM from the combined period are then used to test the hypothesis that differences in observed ENSO character can be reproduced without changes in the linear ENSO dynamics. The frequency and amplitude variations of ENSO seen in each period can be reproduced by any of the three LIMs. However, changes in the direction of zonal SST anomaly propagation in the equatorial Pacific cannot be explained within the paradigm of a single autonomous stochastically forced linear system. This result is suggestive of a possible fundamental change in the dynamical operator governing ENSO and supports the utility of zonal phase propagation, rather than ENSO frequency or amplitude, for diagnosing changes in ENSO dynamics.
Radio‐induced incoherent scatter ion line enhancements with wide altitude extents in the high‐latitude ionosphere
Authors: Senior A. , Rietveld M. T. , Häggström I. , Kosch M. J.
Published: February 2013

Apparent large electron density enhancements deduced from incoherent scatter radar observations during recent high power radio wave injection experiments at the European Incoherent Scatter Scientific Association (EISCAT) facility near Tromsø, Norway have been previously reported. These apparent enhancements extend over a wide altitude range, including the topside ionosphere. Observational evidence is presented, which shows that these apparent density enhancements appear to exhibit aspect‐sensitive backscattering and are not associated with corresponding changes in the frequency of the incoherent scatter plasma line. It is concluded that although an enhancement in the power of the incoherent scatter ion line is observed, it is not the result of an enhancement in the plasma density, but must be due to some other unknown mechanism.
Deep‐sea nutrient loss inferred from the marine dissolved N2/Ar ratio
Authors: Hamme Roberta C. , Emerson Steven R.
Published: February 2013

Some estimates of the budget of bioavailable nitrogen (fixed‐N) suggest that the oceanic nitrogen cycle is grossly out of balance. We use observations of dissolved N2/Ar ratios along abyssal flow paths in the ocean to investigate fixed‐N loss by benthic denitrification, one of the largest uncertainties. Dissolved N2/Ar in the deep‐sea increases from the North Atlantic to the North Pacific. At depths >3500 m, this can be explained by the mixing of low N2/Ar source waters from the North Atlantic with high N2/Ar source waters from the Southern Ocean. Benthic denitrification in sediments bathed by these abyssal waters is below the detection limit. However, measureable increases in N2/Ar at depths of 2000–3000 m between the subtropical and subarctic North Pacific, regions that share the same source water, must be caused by benthic denitrification. The Cascadia Basin, with high denitrification rates and connection to the open North Pacific, is a likely source.