bluuebunny/crossref_metadata_2025 huggingface dataset:
Oxygen inhibition layer of composite resins: effects of layer thickness and surface layer treatment on the interlayer bond strength
Authors: Bijelic‐Donova Jasmina , Garoushi Sufyan , Lassila Lippo V. J. , Vallittu Pekka K.
Published: December 2014

An oxygen inhibition layer develops on surfaces exposed to air during polymerization of particulate filling composite. This study assessed the thickness of the oxygen inhibition layer of short‐fiber‐reinforced composite in comparison with conventional particulate filling composites. The effect of an oxygen inhibition layer on the shear bond strength of incrementally placed particulate filling composite layers was also evaluated. Four different restorative composites were selected: everX Posterior (a short‐fiber‐reinforced composite), Z250, SupremeXT, and Silorane. All composites were evaluated regarding the thickness of the oxygen inhibition layer and for shear bond strength. An equal amount of each composite was polymerized in air between two glass plates and the thickness of the oxygen inhibition layer was measured using a stereomicroscope. Cylindrical‐shaped specimens were prepared for measurement of shear bond strength by placing incrementally two layers of the same composite material. Before applying the second composite layer, the first increment's bonding site was treated as follows: grinding with 1,000‐grit silicon‐carbide (SiC) abrasive paper, or treatment with ethanol or with water‐spray. The inhibition depth was lowest (11.6 μm) for water‐sprayed Silorane and greatest (22.9 μm) for the water‐sprayed short‐fiber‐reinforced composite. The shear bond strength ranged from 5.8 MPa (ground Silorane) to 36.4 MPa (water‐sprayed SupremeXT). The presence of an oxygen inhibition layer enhanced the interlayer shear bond strength of all investigated materials, but its absence resulted in cohesive and mixed failures only with the short‐fiber‐reinforced composite. Thus, more durable adhesion with short‐fiber‐reinforced composite is expected.
Integrating physiological threshold experiments with climate modeling to project mangrove species’ range expansion
Authors: Cavanaugh Kyle C. , Parker John D. , Cook‐Patton Susan C. , Feller Ilka C. , Williams A. Park , Kellner James R.
Published: December 2014

Predictions of climate‐related shifts in species ranges have largely been based on correlative models. Due to limitations of these models, there is a need for more integration of experimental approaches when studying impacts of climate change on species distributions. Here, we used controlled experiments to identify physiological thresholds that control poleward range limits of three species of mangroves found in North America. We found that all three species exhibited a threshold response to extreme cold, but freeze tolerance thresholds varied among species. From these experiments, we developed a climate metric, freeze degree days (FDD), which incorporates both the intensity and the frequency of freezes. When included in distribution models, FDD accurately predicted mangrove presence/absence. Using 28 years of satellite imagery, we linked FDD to observed changes in mangrove abundance in Florida, further exemplifying the importance of extreme cold. We then used downscaled climate projections of FDD to project that these range limits will move northward by 2.2–3.2 km yr−1 over the next 50 years.
Geophysical and Hydrologic Studies of Lake Seepage Variability
Authors: Toran Laura , Nyquist Jonathan , Rosenberry Donald , Gagliano Michael , Mitchell Natasha , Mikochik James
Published: December 2014

Variations in lake seepage were studied along a 130 m shoreline of Mirror Lake NH. Seepage was downward from the lake to groundwater; rates measured from 28 seepage meters varied from 0 to −282 cm/d. Causes of this variation were investigated using electrical resistivity surveys and lakebed sediment characterization. Two‐dimensional (2D) resistivity surveys showed a transition in lakebed sediments from outwash to till that correlated with high‐ and low‐seepage zones, respectively. However, the 2D survey was not able to predict smaller scale variations within these facies. In the outwash, fast seepage was associated with permeability variations in a thin (2 cm) layer of sediments at the top of the lakebed. In the till, where seepage was slower than that in the outwash, a three‐dimensional resistivity survey mapped a point of high seepage associated with heterogeneity (lower resistivity and likely higher permeability). Points of focused flow across the sediment–water interface are difficult to detect and can transmit a large percentage of total exchange. Using a series of electrical resistivity geophysical methods in combination with hydrologic data to locate heterogeneities that affect seepage rates can help guide seepage meter placement. Improving our understanding of the causes and types of heterogeneity in lake seepage will provide better data for lake budgets and prediction of mass transfer of solutes or contaminants between lakes and groundwater.
Low‐Temperature Sintering and Microwave Dielectric Properties of MgZrNb2O8 Ceramics with BaCu (B2O5) Addition
Authors: Tang Xin , Yang Hui , Zhang Qi‐long , Zhou Jue‐hui
Published: December 2014

The effects of BaCu (B2O5) doping on sintering characteristics, phase constitute, and dielectric properties of MgZrNb2O8 ceramics were investigated. Results indicated that a small amount of BaCu (B2O5) can effectively lower the sintering temperature of MgZrNb2O8 ceramics from 1300°C to 1100°C due to liquid phase sintering effect. However, the second phase of Ba3Nb8O21 appeared when the addition of BaCu (B2O5) exceeds 2wt%. Typically, 2wt% BaCu (B2O5)‐added MgZrNb2O8 ceramics sintered at 1100°C for 4 h could reach dense structure and exhibited microwave dielectric properties of εr = 25.96, Q×f = 65,064GHz (f = 8.68GHz), and τf = −47 ppm/°C. Moreover, this ceramic has a chemical compatibility with Ag70/Pd30 electrodes, making it a very promising candidate material for the application of microwave multilayer electronic components.
XRD Analysis of the Role of Cesium in Sodium‐Based Geopolymer
Authors: Chlique Christophe , Lambertin David , Antonucci Pascal , Frizon Fabien , Deniard Philippe
Published: December 2014

The purpose of this work was to study the role of cesium in sodium‐based geopolymer and its thermal stability for nuclear waste management. A series of mixed sodium and cesium geopolymer samples (Na1−x
Cs
x
)2O·Al2O3·SiO2·12H2O (referred to as (Na1−

x
Cs
x
)‐GP, where x = 0, 0.08, 0.15, 0.42, 1) have been prepared. All geopolymer samples were heated at 1100°C for 24 h. Pollucite (CsAlSi2O6) and feldspathoid (CsAlSiO4) were crystallized from Cs‐GP. Nepheline (NaAlSiO4) and a small amount of crystallized silica were obtained from Na‐GP. The other geopolymers (Na1−

x
Cs
x
)‐GP (x = 0.08, 0.15, 0.42) led to pollucite and nepheline main phases. Amorphous silica phase was observed in all the geopolymer samples with various amounts. Phase quantification and scanning electron microscope revealed that higher Cs concentrations in Na‐GP tend to decrease the amorphous phase while improving pollucite and nepheline phase quantification. The amorphous geopolymers have also been studied by pair distribution function analysis. Tetrahedral chains formed by T–O bonding (with T = Si, Al) were shown to be more tighten around Cs+ than around Na+. It led to shorter Cs–T bond than Na–T bond matching the higher solvation property of Na+. Furthermore, thermal study analysis pointed out the fact that geopolymer samples (Na1−

x
Cs
x
)‐GP, can be considered as solid solutions.
Structural and Kinetic Analysis of BaCl2 Nanocrystals in Fluorochlorozirconate Glass‐Ceramics
Authors: Alvarez Carlos J. , Leonard Russell L. , Gray Sharon K. , Johnson Jacqueline A. , Petford‐Long Amanda K.
Published: December 2014

The presence of BaCl2 nanocrystals and the crystallographic phase that they adopt controls the optical behavior of fluorochlorozirconate glass‐ceramics. We have used in situ X‐ray diffraction heating experiments and ex situ transmission electron microscopy to follow the BaCl2 nanocrystal nucleation and growth processes as a function of heating rate and isothermal hold temperature. The BaCl2 nanocrystals nucleate with the hexagonal crystal structure and grow as spherical particles to a size of ~10 to 20 nm. They then undergo a structural transformation to the orthorhombic phase and their shape changes to rounded disks, with diameters ranging from 150 to 250 nm, and thicknesses ranging from 80 to 120 nm. The change in size results from Ostwald ripening of the hexagonal BaCl2 nanocrystals to form the orthorhombic BaCl2 nanocrystals.
White‐Emitting Tuning and Energy Transfer in Eu2+/Mn2+‐Substituted Apatite‐Type Fluorophosphate Phosphors
Authors: Guo Ning , Jia Chengzheng , Li Jing , Zhao Yuefeng , Ouyang Ruizhuo , Lü Wei
Published: December 2014

Herein, a series of Eu2+&Mn2+substituted fluorophosphates Ca6Gd2Na2(PO4)6F2 phosphor with apatite structure have been synthesized and investigated by the powder X‐ray diffraction, photoluminescence spectra, fluorescence decay curves, thermal quenching, and chromaticity properties. Particularly, both Eu2+ and Mn2+ emissions at the two different lattice sites 4f and 6h in Ca6Gd2Na2(PO4)6F2 matrix have been identified and discussed. The dual energy transfer of Eu2+→Mn2+ and Gd3+→Mn2+ in Ca6Gd2Na2(PO4)6F2:Eu2+,Mn2+ samples have been validated and confirmed by the photoluminescence spectra. The dependence of color‐tunable on the activator concentration of Mn2+ was investigated to realize white light emission. By varying the doping concentration of the Mn2+ ion, a series of tunable colors including pure white light and candle light are obtained under the excitation of 350 nm. Moreover, the fluorescence decay curves have been fitted and analyzed using the Inokuti–Hirayama theoretical model to estimate the Eu–Mn interaction mechanism. We also investigated temperature‐dependent photoluminescence quenching characteristics according to the Arrhenius equation. Preliminary studies on the properties of the phosphor indicated that the obtained phosphors might have potential application as a single‐component white‐emitting phosphor for UV‐based white LEDs.
Microstructural Features and Functional Properties of Bilayered BaTiO3/BaTi1−xZrxO3 Ceramics
Authors: Amaral Thiago Martins , Antonelli Eduardo , Ochoa Diego Alejandro , García José Eduardo , Hernandes Antonio Carlos
Published: December 2014

Validity of mixture rule for dielectrics in series configuration and the correlation between microstructure and electrical properties in bilayered BaTiO3/BaTi1−xZrxO3 ceramics were studied. Samples were obtained from BaTi1−xZrxO3 (BTZx) nanopowder synthesized by the polymeric precursor technique and had their microstructure, dielectric, piezoelectric, and ferroelectric properties investigated. These bilayered ceramics' properties were compared to the properties of homogeneous BTZx samples. And, also, the formers' electrical permittivities were compared with the predictions of the simple mixture rule. According to the results, the microstructures of the layers do not differ from the microstructure of the corresponding homogeneous BTZx ceramic. And pyroelectric coefficient measurements show that the electrical properties of the interface do not contribute to the functional properties of the bilayered samples. Nevertheless, on increasing Zr4+, the agreement between the experimental and the predicted permittivity of the bilayered ceramics is gradually reduced, mainly at temperatures where the permittivity is governed by the response of the layer containing Zr4+. As a mechanical joint between the layers, the interface induces stresses during sintering due to thermal mismatch between compositions, thereby affecting the bilayers' electrical properties. Our results show that interface's mechanical effects compromise the functional properties of layered ferroelectric ceramics.
In Situ Diffraction from Levitated Solids Under Extreme Conditions—Structure and Thermal Expansion in the Eu2O3–ZrO2 System
Authors: Maram Pardha S. , Ushakov Sergey V. , Weber Richard J.K. , Benmore Chris J. , Navrotsky Alexandra
Published: December 2014

The accurate determination of structure and thermal expansion of refractory materials at temperatures above 1500°C is challenging. Here, for the first time, we demonstrate the ability to reliably refine the structure and thermal expansion coefficient of oxides at temperatures to 2200°C using in situ synchrotron diffraction coupled with aerodynamic levitation. Solid solutions in the Eu2O3–ZrO2 binary system were investigated, including the high‐temperature order–disorder transformation in Eu2Zr2O7. The disordered fluorite phase is found to be stable above 1900°C, and a reversible phase transition to the pyrochlore phase is noticed during cooling. Site occupancies in Eu2Zr2O7 show a gradual increase in disorder on both cation and anion sublattices with increasing temperature. The thermal expansion coefficients of all cubic solid solutions are relatively similar, falling in the range 8.6–12.0 × 10−6 C−1. These studies open new vistas for in situ exploration of complex structural changes in high‐temperature materials.
Abundance of Cottus poecilopus is influenced by O2 saturation, food density and Salmo trutta in three tributaries of the Rožnovská Bečva River, Czech Republic
Authors: Baran R. , Kubecka J. , Kubín M. , Lojkásek B. , Mrkvička T. , Ricard D. , Rulík M.
Published: December 2014

The distribution patterns of alpine bullhead Cottus poecilopus in three tributary streams of the Rožnovská Bečva River (Danube basin) were studied with respect to temperature, oxygen concentration and saturation, shading, current, conductivity, total organic carbon (TOC), nitrates and phosphates, biochemical oxygen demand (BOD5), pH, redox potential, bottom grain structure, density of macroinvertebrates and the abundance of brown trout Salmo trutta. Sites with lower abundance per hectare of C. poecilopus differed significantly in dissolved oxygen saturation, density of macroinvertebrates during the autumn period (positive correlation with C. poecilopus) and in abundance per hectare of S. trutta (negative correlation). These results indicate that these factors significantly influence the distribution of this endangered species in the studied catchment and that stocking of S. trutta will impair its recovery.
Self‐Reported Walking Difficulty Predicts Late‐Life Mortality in Finnish War Veterans: Results from the Veteran 1992 Project Survey
Authors: Leskinen Riitta , Laatikainen Tiina , Peltonen Markku , Levälahti Esko , Antikainen Riitta
Published: December 2014

Objectives

To determine risk factors and their combinations that predict late‐life mortality.

Design

Postal questionnaire.

Setting

Veteran 1992 Project Survey.

Participants

Finnish Second World War veterans living in Finland (177,989 men, 48,745 women), with a participation rate of 93%.

Measurements

Main outcomes were total, cardiovascular disease (CVD), and accident and violence (AAV) mortality. Absolute 10‐year mortality risks for total mortality with combinations of different risk factors were calculated.

Results

The strongest predictor of total mortality was self‐reported walking difficulty (hazard ratio (HR) = 1.74, 95% confidence interval (CI) = 1.71–1.76 in men without disability, HR = 1.62, 95% CI = 1.58–1.67 in men with disability, HR = 1.61, 95% CI = 1.57–1.65 in women). The highest HRs of CVD mortality were for self‐reported walking difficulty among men without disability (HR = 1.98, 95% CI = 1.95–2.02) and among men with disability (HR = 1.88, 95% CI = 1.82–1.94). In women, the highest HR for CVD mortality was for multimorbidity (HR = 1.87, 95% CI = 1.79–1.96). For AAV mortality, the highest HRs were for falls in men and age in women. A combination of walking difficulty and multimorbidity had the highest absolute 10‐year mortality risk for total mortality (0.730 in men without disability, 0.729 in men with disability, 0.487 in women).

Conclusion

Self‐reported walking difficulty was the most important predictor of total mortality in all veteran groups and for CVD mortality in men. The study demonstrates the importance of self‐reported walking difficulty and multimorbidity as markers of high mortality risk in Finnish war veterans.
Comparison of the deleterious effects of binge drinking‐like alcohol exposure in adolescent and adult mice
Authors: Lacaille Hélène , Duterte‐Boucher Dominique , Liot Donovan , Vaudry Hubert , Naassila Mickael , Vaudry David
Published: December 2014

A major cause of alcohol toxicity is the production of reactive oxygen species generated during ethanol metabolism. The aim of this study was to compare the effect of binge drinking‐like alcohol exposure on a panel of genes implicated in oxidative mechanisms in adolescent and adult mice. In adolescent animals, alcohol decreased the expression of genes involved in the repair and protection of oxidative DNA damage such as atr, gpx7, or nudt15 and increased the expression of proapoptotic genes such as casp3. In contrast, in the adult brain, genes activated by alcohol were mainly associated with protective mechanisms that prevent cells from oxidative damage. Whatever the age, iterative binge‐like episodes provoked the same deleterious effects as those observed after a single binge episode. In adolescent mice, multiple binge ethanol exposure substantially reduced neurogenesis in the dentate gyrus and impaired short‐term memory in the novel object and passive avoidance tests. Taken together, our results indicate that alcohol causes deleterious effects in the adolescent brain which are distinct from those observed in adults. These data contribute to explain the greater sensitivity of the adolescent brain to alcohol toxicity.

image

The effects of alcohol exposure were investigated on genes involved in oxidative mechanisms. In adolescent animals, alcohol decreased the expression of genes involved in DNA repair, a potential cause of the observed decrease of neurogenesis. In contrast, in the adult brain, alcohol increased the expression of genes associated with antioxidant mechanisms. Apoptosis was increase in all groups and converged with other biochemical alterations to enhance short‐term memory impairment in the adolescent brain. These data contribute to explain the greater sensitivity of the adolescent brain to alcohol toxicity.
Shopping While Nonwhite: Racial Discrimination among Minority Consumers
Authors: BENNETT ARONTÉ MARIE , HILL RONALD PAUL , DADDARIO KARA
Published: December 2014

“Shopping While Black” refers to negative experiences that African American consumers endure in the marketplace. The term was coined before the turn of the century and the tabulation of the 2000 census. However, this term may be antiquated—not because African Americans no longer have disparate consumer experiences, but because these experiences impact all American minorities. This study examines the prevalence of racially motivated discriminatory experiences across consumer contexts. Specifically, it offers an empirical look at ways that racial minorities believe they are treated in a variety of consumption environments. Results show that minority groups experience similar levels of perceived discrimination: Asian Americans and Hispanic Americans are as frequently victims of marketplace discrimination as are African Americans. Interestingly, these shared experiences do not necessarily translate into similar beliefs in the continued existence of discrimination as a derogatory force for American minority consumers.
Global Professional Service Firms and the Challenge of Institutional Complexity: ‘Field Relocation' as a Response Strategy
Authors: Faulconbridge James , Muzio Daniel
Published: December 2014

In this paper we use the case of the internationalization of English law firms into Italy, and the refocusing of their operations on the city of Milan, to make a number of contributions to existing literatures on responses to institutional complexity. First, we contribute to the literature on how organizations address complexity at the field level, by revealing the role of ‘field relocation' as a particular response strategy. We also identify a number of organizational tactics – re‐scoping, re‐scaling, and re‐staffing – through which ‘field relocation' is accomplished. Second, we also show the importance of further developing our understanding of the geography of institutional fields by highlighting how the ‘receptivity' of different field locations may affect responses to complexity. This identifies the importance of geographically locating fields and sub‐fields in studies of organizational responses to institutional complexity.
Flexible working, work–family conflict, and maternal gatekeeping: The daily experiences of dual‐earner couples
Authors: Radcliffe Laura S. , Cassell Catherine
Published: December 2014

This study explores the impact of flexible working on the daily experiences of work–family conflict for dual‐earner couples with child dependants. In exploring these daily experiences, the occurrence of maternal gatekeeping behaviours, and the relationship between flexible working and such behaviours is investigated. We draw on episodic and longitudinal data from qualitative diaries kept for a 1‐month period by both members of 24 couples (48 participants) as well as from introductory and subsequent in‐depth qualitative interviews with the couples, both together and apart. We report an evidence suggesting that work–family conflicts are experienced and resolved differently, depending on whether it is the male or the female who works flexibly within dual‐earner couples. This link between flexible working and gender is demonstrated to have an important impact on maternal gatekeeping behaviours, which are highlighted as playing a crucial role in such daily experiences and how they are resolved.

Practitioner points

Traditional gender norms still play a role in parents' decisions to work flexibly and workers who opt for non‐traditional routes may feel stigmatized.

HR departments and employers need to promote the legitimacy of male access to flexible working and work–life balance policies, so these are not perceived as opportunities for mothers alone.

Greater father take‐up of work–life balance initiatives that offer more opportunities for involvement in childcare should be encouraged.

Employers should offer a variety of flexible working arrangements to provide employees with desirable and healthy resolution options when faced with incidents of work–family conflict.
The effects of human immunodeficiency virus infection on the expression of the drug efflux proteins P-glycoprotein and breast cancer resistance protein in a human intestine model
Authors: Ellis Kelstan , Marlin Jerry W , Taylor Tracey A H , Fitting Sylvia , Hauser Kurt F , Rice Greg , McRae MaryPeace
Published: December 2014

Objectives

In human immunodeficiency virus (HIV) infection, decreased penetration of antiretroviral drugs is postulated to contribute to HIV persistence within lymphoid-rich regions of the gastrointestinal (GI) tract. However, mechanistic explanations for this phenomenon remain unclear. Specifically, investigations of HIV effects on drug efflux proteins within intestinal models are minimal.

Methods

Using an in-vitro co-culture model of the GI tract, the effects of HIV infection on drug efflux proteins, P-glycoprotein and breast cancer resistance protein (BCRP) were evaluated. The influence of the HIV-1 protein, Tat, and oxidative stress on P-glycoprotein and BCRP was also evaluated.

Key findings

P-glycoprotein expression demonstrated an HIV-induced upregulation in Caco-2 cells over time for cells grown in co-culture with resting lymphocytes. BCRP overall expression increased with HIV exposure in activated primary human lymphocytes co-cultured with Caco-2 cells. Tat treatment resulted in no significant alterations in P-glycoprotein (43% increase), BCRP expression, or oxidative stress.

Conclusions

HIV exposure within an in-vitro intestinal model resulted in increases in P-glycoprotein and BCRP in a cell-specific manner. Additionally, observed changes were not mediated by Tat. Collectively, these results suggest that alterations in BCRP and P-glycoprotein may contribute, in part, to decreased antiretroviral concentrations within the gut-associated lymphoid tissue of the GI tract in HIV infection.
Essential oils and their constituents as skin penetration enhancer for transdermal drug delivery: a review
Authors: Herman Anna , Herman Andrzej P
Published: December 2014

Objectives

In this paper, we focused on essential oils and their constituents as skin penetration enhancers for transdermal drug delivery, mechanism of their action as well as their possible toxicity.

Key findings

Essential oils and their volatile constituents can penetrate through the skin as well as enhance penetration of different drug from topical formulation into the lower skin layers using different mechanisms of action based on (1) disintegration of the highly ordered intercellular lipid structure between corneocytes in stratum corneum, (2) interaction with intercellular domain of protein, which induces their conformational modification, (3) increase the partitioning of a drug. After application to the skin, essential oils and their components are rapidly metabolized, not accumulated in the organism and fast excreted what strongly suggest that they can be successfully use as safe penetration enhancers.

Essential oils and their constituents may be preferred over the traditionally used synthetics materials as safe and suitable permeation enhancers to promote the percutaneous absorption of hydrophilic and lipophilic drugs from topical formulation into the lower skin layers.
New thermosensitive nanoparticles prepared by biocompatible pegylated aliphatic polyester block copolymers for local cancer treatment
Authors: Karavelidis Vassilios , Bikiaris Dimitrios , Avgoustakis Konstantinos
Published: December 2014

Objective

New pegylated thermosensitive polymers were developed to study them as drug vehicles in targeting release nanoparticulate systems of anticancer drugs.

Methods

The drug vehicles were prepared in the form of core-shell nanoparticles using novel polymeric materials synthesized by copolymerization of poly(propylene adipate) (PPAd) and methoxy-polyethylene glycol (mPEG) with different molecular weights. The physical and chemical properties of the synthesized mPEG-PPAd copolymers were studied using several techniques, and their cytocompatibility was evaluated. For drug nanoencapsulation, a water in oil (W/O) emulsification and solvent evaporation technique was used and the prepared nanoparticles were studied for their physical properties, morphology, drug release and anticancer efficacy against cancer cell lines.

Key findings

The size of the nanoparticles lied in a range suitable for tumour targeting. Drug release was affected by the composition of polymer, the temperature and pH of the release medium. The release results obtained indicate that judicious selection of nanoparticles composition may allow for enhanced drug delivery to the tumours following application of local hyperthermia.

Conclusions

The paclitaxel-loaded mPEG-PPAd nanoparticles were found to be cytotoxic against to the human hepatoma HepG2) and the human epithelial (HeLa) cancer cell lines. Enhanced cytotoxicity against the HeLa cells was observed at elevated temperature (42°C compared with 37°C), providing support for the potential usefulness of the mPEG-PPAd nanoparticles for the development of thermo-sensitive anticancer drug delivery systems.
Developing accurate models of the human airways
Authors: Marshall Lindsay J , Oguejiofor Wilson , Willetts Rachel S , Griffiths Helen R , Devitt Andrew
Published: December 2014

Objectives

Particle delivery to the airways is an attractive prospect for many potential therapeutics, including vaccines. Developing strategies for inhalation of particles provides a targeted, controlled and non-invasive delivery route but, as with all novel therapeutics, in vitro and in vivo testing are needed prior to clinical use. Whilst advanced vaccine testing demands the use of animal models to address safety issues, the production of robust in vitro cellular models would take account of the ethical framework known as the 3Rs (Replacement, Reduction and Refinement of animal use), by permitting initial screening of potential candidates prior to animal use. There is thus a need for relevant, realistic in vitro models of the human airways.

Key findings

Our laboratory has designed and characterised a multi-cellular model of human airways that takes account of the conditions in the airways and recapitulates many salient features, including the epithelial barrier and mucus secretion.

Our human pulmonary models recreate many of the obstacles to successful pulmonary delivery of particles and therefore represent a valid test platform for screening compounds and delivery systems.
Synthesis and pharmacological evaluations of 4-hydroxycoumarin derivatives as a new class of anti-S
taphylococcus aureus agents
Authors: Li Zhou-peng , Li Jing , Qu Di , Hou Zheng , Yang Xiao-hui , Zhang Zi-dan , Wang Yu-kun , Luo Xiao-xing , Li Ming-kai
Published: December 2014

Objectives

Due to the increasing prevalence of drug-resistant Staphylococcus aureus infection, we develop novel 4-hydroxycoumarin derivatives as antimicrobials.

Methods

The antibacterial activity of 4-hydroxycoumarin derivatives against drug-susceptive S. aureus (ATCC 29213) and methicillin-resistant S. aureus (MRSA) were evaluated using minimal inhibitory concentration (MIC) assay; the activity of favourable compound was further observed using bacterial growth curves assay and in the MRSA infection mice.

Key findings

Compared with dihydropyran derivatives, compound 1 as one of biscoumarins showed most potent activity with MIC values of 4–8 μg/ml and apparently inhibited the growth rate of S. aureus ATCC 29213 and USA300 strain in concentrations of both 16 and 32 mg/ml. In the mice infected with MRSA USA300, administration of 5 mg/kg compound 1 improved the animal survival rate to 66.7%, and improved the pathological change in lung tissue compared with the infection model animals. No significant cytotoxicity of compound 1 was observed on the umbilical vein endothelial cells (HUVECs) under the concentration of 800 μg/ml.

Conclusion

Compared with the dihydropyran derivatives, biscoumarins exhibited more promising activity against both drug-sensitive and drug-resistant S. aureus, and it is efficacious in treating MRSA infections in mouse models with a favourable safety in human cells.
Filtering of plant functional traits is determined by environmental gradients and by past land use in a Mediterranean coastal marsh
Authors: Batriu Efrem , Ninot Josep Maria , Pino Joan
Published: December 2014

Question

What is the effect of past land use and environmental gradients on plant functional traits within coastal marsh plant communities?

Location

Mediterranean microtidal marshes in the Llobregat Delta, NE Spain.

Methods

We used a data set collected previously comprising 45 vegetation plots with associated soil parameters, water table conditions and past land use. For each species we obtained the values or states for a set of plant functional traits: plant height, leaf dry matter content, specific leaf area, seed production, seed weight, life form and lateral expansion. To account for the effect of phylogeny, we evaluated trait diversity skewness by means of an ultrametric phylogenetic tree specifically constructed for the species studied. The association between both environmental gradients and past disturbance, and plant functional traits was tested by means of RLQ analysis.

Results

Of all the traits, only seed weight showed a phylogenetic signal; consequently, phylogeny was not included in the RLQ analysis. Conductivity was negatively correlated with seed weight, whereas water table conditions and soil ionic balance were negatively correlated with specific leaf area. Past disturbance was negatively correlated with leaf dry matter content and with lateral expansion.

Conclusions

Plant traits of Llobregat Delta coastal marsh communities are conditioned by environmental gradients and by past land use. Soil ionic balance and water table conditions determine key plant functional traits such as specific leaf area. This finding also corroborates the importance of soil ionic balance as a plant life driver in microtidal Mediterranean marshes. The effect of past land use on species traits might, however, be partially indirect and mediated by associated environmental changes.
Functional diversity reveals complex assembly processes on sea‐born volcanic islands
Authors: Karadimou Elpida , Tsiripidis Ioannis , Kallimanis Athanasios S. , Raus Thomas , Dimopoulos Panagiotis
Published: December 2014

Questions

Do the mechanisms driving community assembly differ between two islands of different age and history of vegetation development? How does sampling scale affect the strength that each assembly mechanism poses on the assembly of plant communities?

Location

Volcanic islands (Palea Kameni and Nea Kameni) of Santorini Archipelago, Greece.

Methods

Functional diversity has been proposed as a framework for discriminating among mechanisms of community assembly, such as habitat filtering, limiting similarity and random assembly. We investigated four plant communities in two sea‐born volcanic islands. We recorded plant diversity at scales from 1 m2 to 64 m2. We calculated three indices of functional diversity: functional richness, functional evenness and functional divergence, using 26 functional traits (including vegetative characteristics, ecological preferences and regenerative characteristics). We used null model analysis to test for two different assembly mechanisms: habitat filtering and limiting similarity or random assembly.

Results

The assemblage of the four communities was complex and did not follow a single mechanism. In most cases, finer‐scale patterns indicated randomness, while coarser scales revealed more structured communities. In the older island, the scrub community was mainly defined by limiting similarity. The therophytic community displayed a limited range of functional traits, indicating mainly habitat filtering, but within this range, the evenness of the distribution indicated limiting similarity. On the younger island, the range of traits did not differ from random. However, within this range of traits, one therophytic community showed signs of limiting similarity, while the second therophytic community displayed uneven functional trait distribution, indicating mainly habitat filtering. The three indices reflected different facets of functional diversity and were not correlated, thus we may argue that they are not redundant, and we even detected different mechanisms of assembly within the same community.

Conclusions

The functional diversity of the therophytic communities in the younger island implied no specific assembly mechanism; perhaps due to its age, the community is still at the early stages of colonization (i.e. stochastic processes, such as arrival of new species, prevail). In the older island, the lack of disturbances for a long period allowed the establishment of communities assembled by specific mechanisms, such as competition and habitat filtering.
Neural circuitry of abdominal pain‐related fear learning and reinstatement in irritable bowel syndrome
Authors: Icenhour A. , Langhorst J. , Benson S. , Schlamann M. , Hampel S. , Engler H. , Forsting M. , Elsenbruch S.
Published: December 2014

Background

Altered pain anticipation likely contributes to disturbed central pain processing in chronic pain conditions like irritable bowel syndrome (IBS), but the learning processes shaping the expectation of pain remain poorly understood. We assessed the neural circuitry mediating the formation, extinction, and reactivation of abdominal pain‐related memories in IBS patients compared to healthy controls (HC) in a differential fear conditioning paradigm.

Methods

During fear acquisition, predictive visual cues (CS+) were paired with rectal distensions (US), while control cues (CS−) were presented unpaired. During extinction, only CSs were presented. Subsequently, memory reactivation was assessed with a reinstatement procedure involving unexpected USs. Using functional magnetic resonance imaging, group differences in neural activation to CS+ vs CS− were analyzed, along with skin conductance responses (SCR), CS valence, CS‐US contingency, state anxiety, salivary cortisol, and alpha‐amylase activity. The contribution of anxiety symptoms was addressed in covariance analyses.

Key Results

Fear acquisition was altered in IBS, as indicated by more accurate contingency awareness, greater CS‐related valence change, and enhanced CS+‐induced differential activation of prefrontal cortex and amygdala. IBS patients further revealed enhanced differential cingulate activation during extinction and greater differential hippocampal activation during reinstatement. Anxiety affected neural responses during memory formation and reinstatement.

Conclusions & Inferences

Abdominal pain‐related fear learning and memory processes are altered in IBS, mediated by amygdala, cingulate cortex, prefrontal areas, and hippocampus. Enhanced reinstatement may contribute to hypervigilance and central pain amplification, especially in anxious patients. Preventing a ‘relapse’ of learned fear utilizing extinction‐based interventions may be a promising treatment goal in IBS.
GLABROUS INFLORESCENCE STEMS3 (GIS3) regulates trichome initiation and development in Arabidopsis
Authors: Sun Lili , Zhang Aidong , Zhou Zhongjing , Zhao Yongqin , Yan An , Bao Shengjie , Yu Hao , Gan Yinbo
Published: December 2014

Arabidopsis trichome formation is an excellent model for studying various aspects of plant cell development and cell differentiation. Our previous works have demonstrated that several C2H2 zinc finger proteins, including GIS, GIS2, ZFP5, ZFP6 and ZFP8, control trichome cell development through GA and cytokinin signalling in Arabidopsis.

We identified a novel C2H2 zinc finger protein, GLABROUS INFLORESCENCE STEMS 3 (GIS3), which is a key factor in regulating trichome development in Arabidopsis.

In comparison with wild‐type plants, loss‐of‐function of GIS3 mutants exhibited a significantly decreased number of trichomes in cauline leaves, lateral branches, sepals of flowers, and main stems. Overexpression of GIS3 resulted in increased trichome densities in sepal, cauline leaves, lateral branches, main inflorescence stems and in the appearance of ectopic trichomes on carpels.

The molecular and genetic analyses show that GIS3 acts upstream of GIS, GIS2, ZFP8 and the key trichome initiation factors, GL1 and GL3. Steroid‐inducible gene expression analyses and chromatin immunoprecipitation (ChIP) experiments suggest that GIS and GIS2 are the direct target genes of GIS3.
Host identity is a dominant driver of mycorrhizal fungal community composition during ecosystem development
Authors: Martínez‐García Laura B. , Richardson Sarah J. , Tylianakis Jason M. , Peltzer Duane A. , Dickie Ian A.
Published: December 2014

Little is known about the response of arbuscular mycorrhizal fungal communities to ecosystem development. We use a long‐term soil chronosequence that includes ecosystem progression and retrogression to quantify the importance of host plant identity as a factor driving fungal community composition during ecosystem development.

We identified arbuscular mycorrhizal fungi and plant species from 50 individual roots from each of 10 sites spanning 5–120 000 yr of ecosystem age using terminal restriction fragment length polymorphism (T‐RFLP), Sanger sequencing and pyrosequencing.

Arbuscular mycorrhizal fungal communities were highly structured by ecosystem age. There was strong niche differentiation, with different groups of operational taxonomic units (OTUs) being characteristic of early succession, ecosystem progression and ecosystem retrogression. Fungal alpha diversity decreased with ecosystem age, whereas beta diversity was high at early stages and lower in subsequent stages. A total of 39% of the variance in fungal communities was explained by host plant and site age, 29% of which was attributed to host and the interaction between host and site (24% and 5%, respectively).

The strong response of arbuscular mycorrhizal fungi to ecosystem development appears to be largely driven by plant host identity, supporting the concept that plant and fungal communities are tightly coupled rather than independently responding to habitat.
Reconciling functions and evolution of isoprene emission in higher plants
Authors: Loreto Francesco , Fineschi Silvia
Published: December 2014

Compilation and analysis of existing inventories reveal that isoprene is emitted by c. 20% of the perennial vegetation of tropical and temperate regions of the world. Isoprene emitters are found across different plant families without any clear phylogenetic thread. However, by critically appraising information in inventories, several ecological patterns of isoprene emission can be highlighted, including absence of emission from C4 and annual plants, and widespread emission from perennial and deciduous plants of temperate environments. Based on this analysis, and on available information on biochemistry, ecology and functional roles of isoprene, it is suggested that isoprene may not have evolved to help plants face heavy or prolonged stresses, but rather assists C3 plants to run efficient photosynthesis and to overcome transient and mild stresses, especially during periods of active plant growth in warm seasons. When the stress status persists, or when evergreen leaves cope with multiple and repeated stresses, isoprene biosynthesis is replaced by the synthesis of less volatile secondary compounds, in part produced by the same biochemical pathway, thus indicating causal determinism in the evolution of isoprene‐emitting plants in response to the environment.

Contents

Summary
578

I.
Introduction
578

II.
Isoprene emission has clear biological and ecological patterns
579

III.
Reconciling ecological patterns of isoprene emission with possible evolutionary and functional threads
580

Acknowledgements
581

References
581
Life is physics and chemistry and communication
Authors: Witzany Guenther
Published: December 2014

Manfred Eigen extended Erwin Schroedinger's concept of “life is physics and chemistry” through the introduction of information theory and cybernetic systems theory into “life is physics and chemistry and information.” Based on this assumption, Eigen developed the concepts of quasispecies and hypercycles, which have been dominant in molecular biology and virology ever since. He insisted that the genetic code is not just used metaphorically: it represents a real natural language. However, the basics of scientific knowledge changed dramatically within the second half of the 20th century. Unfortunately, Eigen ignored the results of the philosophy of science discourse on essential features of natural languages and codes: a natural language or code emerges from populations of living agents that communicate. This contribution will look at some of the highlights of this historical development and the results relevant for biological theories about life.
Pharmaceuticals in the environment: expected and unexpected effects on aquatic fauna
Authors: Fabbri Elena
Published: December 2014

A growing database reports that human and veterinary pharmaceutical residues are present in aquatic and terrestrial environments worldwide. Evidence indicates that nontarget organisms may be chronically exposed to low (ng/L to μg/L range) concentrations of a variety of pharmaceuticals, but that even these concentrations may result in significant biological effects. Here are briefly summarized well‐documented examples demonstrating how pharmaceuticals behave differently from conventional pollutants, which suggests that they must be considered when risk to ecosystems and human health is assessed. In particular, examples are presented of expected effects related to the therapeutic mode of action, unwanted/side effects mainly related to oxidative stress, and unexpected effects induced by environmental concentrations of pharmaceuticals in aquatic animals. A list of the most relevant reviews on the subject is also provided to provide a more complete perspective on the effects of environmental pharmaceuticals in nontarget species.
Are E‐cigarettes a safe and good alternative to cigarette smoking?
Authors: Rom Oren , Pecorelli Alessandra , Valacchi Giuseppe , Reznick Abraham Z.
Published: December 2014

Electronic cigarettes (E‐cigarettes) are devices that can vaporize a nicotine solution combined with liquid flavors instead of burning tobacco leaves. Since their emergence in 2004, E‐cigarettes have become widely available, and their use has increased exponentially worldwide. E‐cigarettes are aggressively advertised as a smoking cessation aid; as healthier, cheaper, and more socially acceptable than conventional cigarettes. In recent years, these claims have been evaluated in numerous studies. This review explores the development of the current E‐cigarette and its market, prevalence of awareness, and use. The review also explores the beneficial and adverse effects of E‐cigarettes in various aspects in accordance with recent research. The discussed aspects include smoking cessation or reduction and the health risks, social impact, and environmental consequences of E‐cigarettes.
Durable Purchases over the Later Life Cycle
Authors: Browning Martin , Crossley Thomas F. , Lührmann Melanie
Published: December 2014

We investigate life‐cycle patterns of demand for services from household durables using UK panel data. We take careful account of prices, demographics, labour supply and health. Demand for consumer electronics rises with age, while the demand for household appliances is flat. These findings contrast with the well documented decline in non‐durable consumption at older ages, and suggest that studies that estimate the overall discount rate from nondurable consumption may underestimate consumer patience and the savings required to fund retirement. We also find important non‐separabilities between the demand for durables, labour supply and health status.
Estimating and evaluating Value‐at‐Risk forecasts based on realized variance: empirical evidence from ICE Brent Crude oil futures
Authors: Haugom Erik , Veka Steinar , Lien Gudbrand , Westgaard Sjur
Published: December 2014

This paper is the first to use the concept of realized volatility to forecast Value‐at‐Risk (VaR) for ICE Brent Crude oil futures. We examine sensitivities in the VaR forecasts across intra‐daily sampling frequency used to calculate realized volatility. We evaluate the VaR forecasts using Christoffersen's test for conditional coverage on quantiles of particular interest. Additionally, we examine a percentile–percentile plot of the VaR forecasts for all percentiles. The main empirical results show that very good VaR forecasts can be obtained using Gaussian critical values in combination with volatility forecasts based on realized volatility. An examination of the sampling frequency suggests that the most accurate VaR forecasts are obtained with a sampling frequency of between 1 and 10 min. This has important implications for practitioners operating in the financial oil sector.
Determinants of economic growth in OPEC: an extreme bounds analysis
Authors: Zarra‐Nezhad Mansour , Hosseinpour Fatimah
Published: December 2014

The aim of this study is to identify robust determinants of economic growth in Organization of Petroleum Exporting Countries (OPEC). To examine the robustness of 101 potential determinants of economic growth in OPEC about 11 million regressions are estimated. The results of extreme bounds analysis with the unbalanced panel data of 21 years shows that variety of trade policy measures are robust and support export‐led growth hypothesis. Proxies of export passed very strict test of Levine and Renelt, while oil export is not robust. The results also support conditional‐convergence hypothesis.