bluuebunny/crossref_metadata_2025 huggingface dataset:
Porous gelatin–siloxane hybrid scaffolds with biomimetic structure and properties for bone tissue regeneration
Authors: Lei Bo , Shin Kwan‐Ha , Koh Young‐Hag , Kim Hyoun‐Ee
Published: March 2014

We produced highly porous gelatin–siloxane (GLA‐S) hybrid scaffolds with biomimetic anisotropic porous structure, physiochemical properties, mechanical behaviors and biological functions by treating gelatin–siloxane hybrid gels in an ammonium hydroxide solution. The siloxane used as an inorganic phase could effectively crosslink the gelatin polymer, which allowed for the unidirectional enlargement of ammonia vacuoles during ammonium hydroxide treatment. This created aligned pores in an axial direction when the siloxane contents (10 and 20 wt %) were high. In addition, the gelatin polymer could be uniformly hybridized with the siloxane phase at the molecular level, while intense interaction between these two phases could be achieved. This resulted in a significant increase in mechanical properties. The GLA‐S hybrid scaffold with a siloxane content of 10 wt % showed reasonably high compressive yield strength of 4.2 ± 0.1 MPa and compressive modulus of 84 ± 5 MPa at a porosity of 86 vol %, which would be comparable to those of natural cancellous bone. In addition, the GLA‐S hybrid scaffold had good biocompatibility assessed by in vitro cell tests using pre‐osteoblast MC3T3‐E1 cells. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 102B: 1528–1536, 2014.
Structure‐Properties Relationship of In Situ Synthesized Poly(Butylene Succinate)/Silica Nanocomposites: Application in Extrusion Blowing of Films
Authors: Jacquel Nicolas , Saint‐Loup René , Pascault Jean‐Pierre , Rousseau Alain , Fenouillot Françoise
Published: March 2014

The melt synthesis of poly(butylene succinate)/silica (PBS/SiO2) nanocomposites is investigated via an in situ approach. The use of two types of nanosilica, fumed (or pyrogenic) silica and colloidal silica, is described. In all cases, the addition of silica favors an increase of the melt viscosity during the polycondensation step. This behavior is attributed to both polymer–silica interactions and PBS chain coupling via possible reaction with silica silanols. Biodegradable film is a promising application for PBS. In this context, it is proved that silica greatly facilitates PBS processing by extrusion blowing (a longitudinal draw ratio of 16 is attained). Moreover, tensile tests performed on films demonstrate significant reinforcement of the material with the addition of the nanofiller. The dispersion of the particles into the polymer matrix is assessed by transmission electron microscopy and further characterized by image analysis. It appears that pyrogenic and colloidal silica particles are regularly dispersed in the polymer matrix and that this dispersion is stable upon film blowing.
Drastic Tuning of the Photonic Properties of «(Push–Pull)n» trans‐Bis(ethynyl)bis(Tributylphosphine)Platinum(II)‐Containing Polymers
Authors: Wang Xiaorong , Fortin Daniel , Brisard Gessie , Harvey Pierre D.
Published: March 2014

The trans‐Pt(PBu3)2Cl2 complex reacts with 1 equiv. of 2,6‐diethynyl‐AQ and 2 equiv. of 2‐ethynyl‐AQ (AQ = anthraquinone) to form the polymer (trans‐Pt(2,6‐diethynyl‐AQ)2(PBu3)2)n, 1, and the model compounds, 2, trans‐Pt(PBu3)2(2‐ethynyl‐AQ)2 (in a 20:1 ratio as trans‐(2a) and cis‐(2b) rotational isomers), respectively. These redox‐active and luminescent materials have been characterized by gel permeation chromatography, thermal gravimetric analysis, X‐ray crystallography, electrochemistry, photophysics, and DFT computations (B3LYP). The typical π,π* T2→S0 phosphorescence centered on the trans‐Pt(PBu3)2(aryl)2 chromophore, [Pt], generally encountered for the analogous polymers (trans‐Pt(PBu3)2(aryl)2‐acceptor)n (acceptor = quinonediimine, QN2; anthraquinone diimine, AQN2), for which the CT T1→S0 emission is silent, has been completely annihilated and replaced by a red‐shifted T1→S0 emission in 1 and 2a, which arise from a triplet charge transfer excited state [Pt]→AQ.

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In situ thermal reduction of graphene oxide forming epoxy nanocomposites and their dielectric properties
Authors: Toselli M. , Fabiani D. , Mancinelli P. , Fréchette M. , Heid T. , David E. , Saccani A.
Published: March 2014

The electrical properties of epoxy based composites modified by low amounts of graphite oxide, below the conduction threshold, have been investigated. The composites have been prepared without the use of solvents by direct sonication of graphite oxide (GO) powders and of chemically modified and partially reduced GO powders in the based epoxy monomer. Through a mild thermal treatment, in situ reduction of the previously dispersed GO has been obtained directly inside the epoxy resins. The changes in the electrical response of the materials thus obtained have been compared to that of pristine unmodified epoxy resin. Data so far collected underline the possibility to tune the electrical conductivity of the composites within two orders of magnitude and to increase the values of permittivity without significantly worsening dielectric losses. POLYM. COMPOS., 36:294–301, 2015. © 2014 Society of Plastics Engineers
A detection algorithm for drug‐induced liver injury in medical information databases using the Japanese diagnostic scale and its comparison with the Council for International Organizations of Medical Sciences/the Roussel Uclaf Causality Assessment Method scale
Authors: Hanatani Tadaaki , Sai Kimie , Tohkin Masahiro , Segawa Katsunori , Kimura Michio , Hori Katsuhito , Kawakami Junichi , Saito Yoshiro
Published: March 2014

Purpose

Drug‐induced liver injury (DILI) is one of the primary targets for pharmacovigilance using medical information databases (MIDs). Because of diagnostic complexity, a standardized method for identifying DILI using MIDs has not yet been established. We applied the Digestive Disease Week Japan 2004 (DDW‐J) scale, a Japanese clinical diagnostic criteria for DILI, to a DILI detection algorithm, and compared it with the Council for International Organizations of Medical Sciences/the Roussel Uclaf Causality Assessment Method (CIOMS/RUCAM) scale to confirm its consistency. Characteristics of DILI cases identified by the DDW‐J algorithm were examined in two Japanese MIDs.

Methods

Using an MID from the Hamamatsu University Hospital, we constructed a DILI detection algorithm on the basis of the DDW‐J scale. We then compared the findings between the DDW‐J and CIOMS/RUCAM scales. We examined the characteristics of DILI after antibiotic treatment in the Hamamatsu population and a second population that included data from 124 hospitals, which was derived from an MID from the Medical Data Vision Co., Ltd. We performed a multivariate logistic regression analysis to assess the possible DILI risk factors.

Results

The concordance rate was 79.4% between DILI patients identified by the DDW‐J and CIOMS/RUCAM; the Spearman rank correlation coefficient was 0.952 (P < 0.0001). Men showed a significantly higher risk for DILI after antibiotic treatments in both MID populations.

Conclusions

The DDW‐J and CIOMS/RUCAM algorithms were equivalent for identifying the DILI cases, confirming the utility of our DILI detection method using MIDs. This study provides evidence supporting the use of MID analyses to improve pharmacovigilance. Copyright © 2014 John Wiley & Sons, Ltd.
Morphology and properties of perfluorosulfonic acid polymer/perfluorocarboxylic acid polymer blend membranes
Authors: Wang Jing , Wang Xuejun , Dou Peng , Zhang Heng , Zhang Yongming
Published: March 2014

A melt‐extruded method has been used to prepare blend membranes of Perfluorosulfonic Acid Polymer (PFSA) and Perfluorocarboxylic Acid Polymer (PFCA) with different combination ratios. Fourier Transform Infrared (FT‐IR) and X‐ray Diffraction (XRD) analyses have showed that the chemical structure and crystallization behaviour of both polymers remained unchanged in the blend membrane, and the crystallinity has been increased for the blend membrane with a higher weight fraction of PFCA. According to the results obtained from Scanning Electron Microscope (SEM), PFSA and PFCA polymers are well compatible, forming mixed aggregates containing both sulphonyl and carboxyl ions. Surprisingly, a membrane containing a 50:50 ratio of PFSA/PFCA has showed microphase separation, and it possesses the smallest ionic cluster size among all the blend membranes prepared, as illustrated by the Small Angle X‐ Ray Scattering (SAXS) analysis. In addition, when the PFCA content was increased, the ion exchange capacity (IEC) for blend membranes remained the same, while their water uptake and proton conductivity have decreased rapidly. Compared with the PFSA/PFCA two‐layered membrane, this PFSA/blend/PFCA membrane not only maintained respectable electrolysis property, also exhibited significantly higher peel strength, especially after the hydrolization process; plus, it has showed excellent resistance to the peeling damage under the operational conditions of chlor‐alkali electrolytic cells. POLYM. ENG. SCI., 55:180–189, 2015. © 2014 Society of Plastics Engineers
Epitope mapping and targeted quantitation of the cardiac biomarker troponin by SID‐MRM mass spectrometry
Authors: Zhao Cheng , Trudeau Beth , Xie Helen , Prostko John , Fishpaugh Jeffrey , Ramsay Carol
Published: March 2014

The absolute quantitation of the targeted protein using MS provides a promising method to evaluate/verify biomarkers used in clinical diagnostics. In this study, a cardiac biomarker, troponin I (TnI), was used as a model protein for method development. The epitope peptide of TnI was characterized by epitope excision followed with LC/MS/MS method and acted as the surrogate peptide for the targeted protein quantitation. The MRM‐based MS assay using a stable internal standard that improved the selectivity, specificity, and sensitivity of the protein quantitation. Also, plasma albumin depletion and affinity enrichment of TnI by anti‐TnI mAb‐coated microparticles reduced the sample complexity, enhanced the dynamic range, and further improved the detecting sensitivity of the targeted protein in the biological matrix. Therefore, quantitation of TnI, a low abundant protein in human plasma, has demonstrated the applicability of the targeted protein quantitation strategy through its epitope peptide determined by epitope mapping method.
Micro analysis to map the glycome code
Authors: Simone Giuseppina
Published: March 2014

Proteins play pivotal functions in cells; the study of these proteins and functions is the realm of proteomics. Less appreciated is that the proteins can be sugar coated and that glycosylation affects how the immune system recognizes the protein, as being friend or foe. Protein glycosylation and glycan‐protein interactions are involved in malignant processes, including those that underlie tumor, diabetes, and Alzheimer's disease. Some aspects of the glycome, including the role that simple glycans and their derivates have in the modulation of cellular behavior, have not yet been elucidated. Novel interdisciplinary technologies are needed to improve our understanding of those fields. Here, we describe the hierarchical levels of glycan structure and discuss the potential of microfluidics to gain an improved understanding of those mechanisms.
Optimization of an α‐(Amino acid)‐N‐carboxyanhydride polymerization using the high vacuum technique: Examining the effects of monomer concentration, polymerization kinetics, polymer molecular weight, and monomer purity
Authors: Kowtoniuk Robert A. , Pei Tao , DeAngelo Caitlin M. , Waldman Jacob H. , Guidry Erin N. , Williams J. Michael , Garbaccio Robert M. , Barrett Stephanie E.
Published: March 2014

l‐Ornithine‐based poly(peptides) have been widely utilized in the field of drug delivery, however few studies have been conducted examining the details of polymerization. In this article, the effects of monomer concentration, polymerization kinetics, polymer molecular weight and monomer purity were investigated using l‐carboxybenzyl (Cbz)‐ornithine as a model monomer. The mechanism of polymerization herein follows the normal amine mechanism to produce poly(peptides) having controlled molecular weights, known chain ends and a narrow polydispersity index (PDI). A preferred monomer concentration range was determined, which required minimal polymerization times and allowed for predictable and reproducible molecular weights with narrow PDIs. The impact of monomer purity on the polymerization was established and monomer purification conditions are reported, which produce high‐purity monomer after a single recrystallization. Additionally, the optimized polymerization conditions and monomer purification protocol were combined with a sequential monomer addition technique to produce high molecular weight poly(ornithine) with a narrow PDI and known chain ends. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1385–1391
Two‐Step direct arylation for synthesis of naphthalenediimide‐based conjugated polymer
Authors: Nohara Yuta , Kuwabara Junpei , Yasuda Takeshi , Han Liyuan , Kanbara Takaki
Published: March 2014

A naphthalenediimide (NDI)‐based conjugated polymer was synthesized by a two‐step direct C‐H arylation sequence. In the first step, two ethylenedioxythiophene units were coupled to NDI by direct arylation. In the second step, the direct arylation polycondensation of the monomer, formed in the first step, with 2,7‐dibromo‐9,9‐dioctylfluorene afforded the corresponding NDI‐based conjugated polymer (PEDOTNDIF) with molecular weight of 21,500 in 91% yield. The optical and electrochemical properties of the polymer were evaluated. The polymer showed ambipolar behavior in organic field‐effect transistors (OFETs). The electron mobility of PEDOTNDIF was estimated to be 2.3 × 10−6 cm2 V−1 s−1 using an OFET device with source‐drain (S‐D) Au electrodes. A modified OFET device with S‐D MgAg electrodes increased the electron mobility for PEDOTNDIF to 1.0 × 10−5 cm2 V−1 s−1 due to the more suitable work function of these electrodes, which reduced the injection barrier to the semiconducting polymer. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1401–1407
Survey of Plasmonic Nanoparticles: From Synthesis to Application
Authors: Kretschmer Florian , Mühlig Stefan , Hoeppener Stephanie , Winter Andreas , Hager Martin D. , Rockstuhl Carsten , Pertsch Thomas , Schubert Ulrich S.
Published: March 2014

The unique properties of plasmonic nanostructures have fuelled research based on the tremendous amount of potential applications. Their tailor‐made assemblies in combination with the tunable size and morphology of the initial building blocks allow for the creation of materials with a desired optical response. In this respect, it is crucial to synthesize nanoparticles with a defined shape that are at the core of such developments. Moreover, the interaction of individual nanoparticles with an incident electromagnetic field cannot only be influenced by their structure, but in fact, also by their spatial arrangement to each other. To harvest such opportunities, a profound theoretical understanding of these interactions is required as well as concise strategies to create such ordered assemblies. A quantitative evaluation of their optical properties can only be conducted when discrete structures of high uniformity can be achieved. As a consequence, separation steps have to be applied in order to obtain materials of high purity and uniformity. This also allows for an easier structural characterization of the nanoparticles and their assembled superstructures. In this progress report, an overview about the current development in this field of research is provided.
Self‐bending hydrogel actuation for electrode shafts in cochlear implants
Authors: Stieghorst Jan , Tegtmeier Katharina , Aliuos Pooyan , Zernetsch Holger , Glasmacher Birgit , Doll Theodor
Published: March 2014

A self‐bending electrode shaft for application in cochlear implants (CI) is presented. It is desired to reduce the distance between the electrode contacts and nerve cells in the modiolus of the inner ear. Therefore a coextrusion and overmolding device to fabricate a novel electrode shaft consisting of an eccentrically positioned hydrogel swelling actuator was established. Finite‐element‐analysis (FEA) was performed to analyse the self‐bending effect in relationship to the applied hydrostatic pressure. The mechanical actuation of a fabricated electrode shaft was tested in vitro by injection of water into the hydrogel. Curving of the electrode shaft was observed. Osmotic pressure in relation to the mass fraction of the swelling polymer inside the hydrogel was calculated.
Spatial Pattern of Phytoplankton Based on the Morphology‐Based Functional Approach along a River–Floodplain Gradient
Authors: Mihaljević M. , Stević F. , Špoljarić D. , Pfeiffer T. Žuna
Published: March 2014

Current efforts to yield an appropriate method that would simplify the use of phytoplankton in the ecological evaluation of freshwaters resulted in different approaches based on clustering phytoplankton organisms. In this study, we applied the morphology‐based functional group (MBFG) concept to determine the spatial changes of phytoplankton in the natural riverine floodplain of the alluvial reaches of the Danube River along the horizontal gradient from the river towards the floodplain habitats.

The obtained results showed that the magnitude of environmental changes depended on alternations in hydrological variables (hydropattern and water level) that influenced changes in the physical and chemical conditions. High‐intensity flood pulses caused environmental homogenizations and nitrate enrichment of the floodplain habitats. Phytoplankton dynamics were strongly associated with the environmental changes, and using the MBFG approach, two basic hydrological conditions were identified: inundation phase dominated by diatoms (GVI) and isolation phase dominated by filamentous cyanobacteria (GIII). Total diatom biomass decreased along the floodplain gradient with a diminishing of physical constraints, and site‐specific variables became more important in favouring diatom assemblages. The different response of cyanobacterial species to mixing regime was of particular significance for species successions during bloom period. Altogether, classifying very diverse diatoms (centrics and pennates and planktonic and benthic) and cyanobacterial taxa into single groups represents a weakness of the MBFG approach, which might make it impossible to reflect all the ecological differences governed by environmental constraints along river–floodplain gradients. Copyright © 2014 John Wiley & Sons, Ltd.
Concurrency control of bulk access transactions on a parallel disk database machine
Authors: Ohmori Tadashi , Kitsuregawa Masaru , Tanaka Hidehiko
Published: March 2014

A scheme for concurrency control of bulk access transactions on a Shared‐Nothing database machine is described. A “weighted transaction precedence graph” that expresses transaction cost as well as serializability and a cautions scheduler based on it are capable of producing serializable schedules with decreased data and resource contention. In simulations the new scheduler achieved throughout levels 1.3 to 2 times those attainable with conventional locking protocols.
Object identification based on uncertain sparse sensor information
Authors: Kawashima Toshio , Shirakawa Yoichi , Aoki Yoshinao
Published: March 2014

This paper discusses the problem of object identification based on spatially sparse uncertain information. First, it is assumed that the sensor information is composed of two kinds of information, i.e., the geometrical parameter distribution and the decision tree. The description format for the uncertain sensor information is defined. Then a method is presented where the set of uncertain sensor information obtained by the measurement of the object is combined (fusion), and the match between the object and the model is examined. Finally, the case of measurement of the two‐dimensional figure by the sparse shape sensor is considered. The process of fusion is demonstrated and the usefulness of the proposed method is shown by a matching experiment.

In the proposed method, an object identification procedure is employed where the information obtained from several sensors is described as geometrical parameters together with their error distributions, and the match to the model is examined by combining those parameters. The information, for which more than one decision tree interpretation is possible, is described as the basic probability of the Dempster‐Shafer theory. The parameters are fused for each interpretation, and the reliability of the result of fusion is estimated by the combination rule. As a simulation experiment, the case with the tactile sensor in contact with a column object is considered, and the object identification process is demonstrated.
Scale‐space filtering for periodic waveforms
Authors: Wada Toshikazu , Gu Yi He , Sato Makoto
Published: March 2014

Scale‐space filtering is one of the hierarchical representations of the waveform in which the given waveform is observed in multiscale measurement. Scale‐space filtering using the Gaussian filter, whose bandwidth varies with the scale, continuously blurs the waveform. It has a property that the number of zero crossings of the waveform decreases monotonically while increasing the scale. This property is called monotonicity.

The relations among intervals sectioned by zero crossings are represented by a tree structure. Thus, most of the past studies on the scale‐space filtering can be viewed as the studies of the waveforms in (‐∞, ∞). However, there has been no adequate discussion on the scale‐space filtering of the periodic waveform.

This paper describes a method to construct scale‐space filtering so that the monotonicity of the zero crossings applies also to the periodic waveform. By analyzing the zero crossings of the waveform, essential differences between the ordinary scale‐space filtering and the periodic scale‐space filtering are indicated. An example is presented for the structural analysis of the speech waveform, and the difference between the hierarchical structures derived by those scale‐space filters is discussed.
Connecting Poverty to Purchase in Informal Markets
Authors: London Ted , Esper Heather , Grogan‐Kaylor Andrew , Kistruck Geoffrey M.
Published: March 2014

Base‐of‐the‐Pyramid (BoP) enterprises seek to serve impoverished customers in informal markets. While BoP enterprises have grown in prominence, comparatively little multidimensional theoretical work has explored why these customers ultimately elect to purchase their products. Using a sample of 555 potential customers in rural India, our results indicate that the influence of different dimensions of poverty on likelihood of purchase is largely a function of the strength of the formal institutional environment. Specifically, stronger formal institutional environments can act as both a complement to, and a substitute for, the influence of individual‐ and network‐level norms on purchasing decisions in informal markets. Copyright © 2014 Strategic Management Society.
Topical Delivery of Avastin to the Posterior Segment of the Eye In Vivo Using Annexin A5‐associated Liposomes
Authors: Davis Benjamin M. , Normando Eduardo M. , Guo Li , Turner Lisa A. , Nizari Shereen , O'Shea Paul , Moss Stephen E. , Somavarapu Satyanarayana , Cordeiro M. Francesca
Published: March 2014

Effective delivery to the retina is presently one of the most challenging areas in drug development in ophthalmology, due to anatomical barriers preventing entry of therapeutic substances. Intraocular injection is presently the only route of administration for large protein therapeutics, including the anti‐Vascular Endothelial Growth Factors Lucentis (ranibizumab) and Avastin (bevacizumab). Anti‐VEGFs have revolutionised the management of age‐related macular degeneration and have increasing indications for use as sight‐saving therapies in diabetes and retinal vascular disease. Considerable resources have been allocated to develop non‐invasive ocular drug delivery systems. It has been suggested that the anionic phospholipid binding protein annexin A5, may have a role in drug delivery. In the present study we demonstrate, using a combination of in vitro and in vivo assays, that the presence of annexin A5 can significantly enhance uptake and transcytosis of liposomal drug carrier systems across corneal epithelial barriers. This system is employed to deliver physiologically significant concentrations of Avastin to the posterior of the rat eye (127 ng/g) and rabbit retina (18 ng/g) after topical application. Our observations provide evidence to suggest annexin A5 mediated endocytosis can enhance the delivery of associated lipidic drug delivery vehicles across biological barriers, which may have therapeutic implications.
Controllable and Facile Fabrication of Gold Nanostructures for Selective Metal‐Assisted Etching of Silicon
Authors: Zhang Xinyue , Zhu Juan , Huang Xiaopeng , Qian Qiuping , He Yonglin , Chi Lifeng , Wang Yapei
Published: March 2014

A method with the combination of organic‐vapor‐assisted polymer swelling and nanotransfer printing (nTP) is used to manufacture desirable patterns consisting of gold nano‐clusters on silicon wafers for Au‐assisted etching of silicon. This method remarkably benefits to the size control and regional selection of the deposited Au. By tuning the thickness of the Au films deposited on the polydimethylsiloxane (PDMS) stamps, along with the swelling of PDMS stamps in acetone atmosphere, the Au films are cracked into diverse nanostructures. These nanostructures are covalently transferred onto silicon substrates in a large scale and enable to accelerate the chemical etching of silicon. The etched areas are composed of porous structures which can be readily distinguished from the surroundings on optical microscope. PDMS stamps and the Au clusters provide the control over the feature of the etched areas and the porous silicon, respectively. The silicon surfaces with patterned porous features offer a platform for exploiting new functional templates, for example, they present a diversity of antireflective and fluorescent performance.
Quantile regression analysis of length‐biased survival data
Authors: Wang Huixia Judy , Wang Lan
Published: March 2014

Length‐biased time‐to‐event data commonly arise in epidemiological cohort studies and cross‐sectional surveys. Ignoring length‐biased sampling often leads to severe bias in estimating the survival time in the general population. We propose a flexible quantile regression framework for analysing the covariate effects on the population survival time under both length‐biased sampling and random censoring. This framework allows for easy interpretation of the statistical model. Furthermore, it allows the covariates to have different impacts at different tails of the survival distribution and thus is able to capture important population heterogeneity. Using an unbiased estimating equation approach, we develop a new estimator that allows the censoring variable to depend on covariates in a non‐parametric way. We establish the consistency and asymptotic normality for the proposed estimator. A lack‐of‐fit test is proposed for diagnosing the adequacy of the population quantile regression model. The finite sample performance of the proposed methods is assessed through a simulation study. We demonstrate that the proposed method is effective in discovering interesting covariate effects by analysing the Canadian Study of Health and Aging dementia data. Copyright © 2014 John Wiley & Sons Ltd
Using Qualitative Research to Assess Teaching and Learning in Technology‐Infused TILE Classrooms
Authors: Van Horne Sam , Murniati Cecilia Titiek , Saichaie Kem , Jesse Maggie , Florman Jean C. , Ingram Beth F.
Published: March 2014

This chapter describes the results of an assessment project whose purpose was to improve the faculty‐development program for instructors who teach in technology‐infused TILE (Transform, Interact, Learn, Engage) classrooms at the University of Iowa. Qualitative research methods were critical for (1) learning about how students and instructors interacted in these new learning spaces and (2) improving faculty development to ensure that instructors could design and implement effective learning activities in the TILE environment.
Coffeehouse as Classroom: Examination of a New Style of Active Learning Environment
Authors: Morrone Anastasia S. , Ouimet Judith A. , Siering Greg , Arthur Ian T.
Published: March 2014

This chapter explores whether a new learning space, designed to be more like a café than a classroom, provides an environment that facilitates active and collaborative learning.
Strategies to Address Common Challenges When Teaching in an Active Learning Classroom
Authors: Petersen Christina I. , Gorman Kristen S.
Published: March 2014

This chapter provides practical strategies for addressing common challenges that arise for teachers in active learning classrooms. Our strategies come from instructors with experience teaching in these environments.
A review of PEM fuel cell durability: materials degradation, local heterogeneities of aging and possible mitigation strategies
Authors: Dubau Laetitia , Castanheira Luis , Maillard Frédéric , Chatenet Marian , Lottin Olivier , Maranzana Gaël , Dillet Jérôme , Lamibrac Adrien , Perrin Jean‐Christophe , Moukheiber Eddy , ElKaddouri Assma , De Moor Gilles , Bas Corine , Flandin Lionel , Caqué Nicolas
Published: March 2014

Through a tight collaboration between chemical engineers, polymer scientists, and electrochemists, we address the degradation mechanisms of membrane electrode assemblies (MEAs) during proton exchange membrane fuel cell (PEMFC) operation in real life (industrial stacks). A special attention is paid to the heterogeneous nature of the aging and performances degradation in view of the hardware geometry of the stack and MEA. Macroscopically, the MEA is not fuelled evenly by the bipolar plates and severe degradations occur during start‐up and shut‐down events in the region that remains/becomes transiently starved in hydrogen. Such transients are dramatic to the cathode catalyst layer, especially for the carbon substrate supporting the Pt‐based nanoparticles. Another level of heterogeneity is observed between the channel and land areas of the cathode catalyst layer. The degradation of Pt3Co/C nanocrystallites employed at the cathode cannot be avoided in stationary operation either. In addition to the electrochemical Ostwald ripening and to crystallite migration, these nanomaterials undergo severe corrosion of their high surface area carbon support. The mother Pt3Co/C nanocrystallites are continuously depleted in Co, generating Co2+ cations that pollute the ionomer and depreciate the performance of the cathode. Such cationic pollution has also a negative effect on the physicochemical properties of the proton‐exchange membrane (proton conductivity and resistance to fracture), eventually leading to hole formation. These defects were localized with the help of an infrared camera. The mechanical fracture‐resistance of various perfluorosulfonated membranes further demonstrated that polytetrafluoroethylene‐reinforced membranes better resist hole formation, due to their high resistance to crack initiation and propagation. WIREs Energy Environ 2014, 3:540–560. doi: 10.1002/wene.113

This article is categorized under:

Fuel Cells and Hydrogen > Science and Materials

Fuel Cells and Hydrogen > Systems and Infrastructure

Energy Research & Innovation > Science and Materials
Effects of intensity and seasonal timing of disturbances on a rocky intertidal benthic community on the southern coast of Korea
Authors: Kim Sangil , Kang Yun Hee , Choi Chang Jae , Won Nam‐Il , Seo In‐Soo , Lee Hyuk Je , Jung Sukgeun , Park Sang Rul
Published: March 2014

The effects of intensity and timing of disturbances on recovery of marine benthic organisms were investigated on a rocky intertidal shore in Gwangyang Bay, Korea. We hypothesized that the recovery pattern of the benthic community structure would be affected by disturbance intensity and season. Twenty‐eight permanent plots were set up, with disturbance intensity (cleared plots and sterile plots) and seasonal disturbance (fall 1999 and spring 2000) incorporated into the experimental design. To monitor natural seasonal variation in benthic community abundances, we established seven permanent unmanipulated plots. Turf‐forming algae were observed in the unmanipulated plots throughout the experimental period, whereas green algae and invertebrate presence varied with season. In the disturbance‐intensity experiment, turf‐forming and green algae were dominant in cleared plots. The highest coverage of sessile organisms was observed in sterile plots, which exhibited the highest species richness because of their relatively low macroalgal coverage. Seasonal effects of disturbance were an important factor in the recovery pattern of benthic organisms under high disturbance intensity. Coverage of green algae was higher in sterile spring plots than in sterile fall plots; this result was attributed to low spatial competition, as the disturbances occurred just before green algal blooms. On the other hand, the abundances of barnacles and bivalves were highest on sterile fall plots, as these organisms were suppressed by green algal blooms in other periods. These results indicate that the effects of disturbance intensity on benthic community recovery patterns can be influenced by season of disturbance.
Effective conditions for the reflection of an acoustic wave by low-porosity perforated plates
Authors: Laurens S. , Piot E. , Bendali A. , Fares M’B. , Tordeux S.
Published: March 2014

This paper describes an investigation of the acoustic properties of a rigid plate with a periodic pattern of holes, in a compressible, ideal, inviscid fluid in the absence of mean flow. Leppington & Levine (J. Fluid Mech., vol. 61, 1973, pp. 109–127) obtained an approximation of the reflection and transmission coefficients of a plane wave incident on an infinitely thin plate with a rectangular array of perforations, assuming that a characteristic size of the perforations is negligible relative to that of the unit cell of the grating, itself assumed to be negligible relative to the wavelength. One part of the present study is of methodological interest. It establishes that it is possible to extend their approach to thick plates with a skew grating of perforations, thus confirming recent results of Bendali et al. (SIAM J. Appl. Math., vol. 73 (1), 2013, pp. 438–459), but in a much simpler way without using complex matched asymptotic expansions of the full wave or to a grating of multipoles. As is well-known, effective compliances for the plate can then be derived from the corresponding approximations of the reflection and transmission coefficients. These compliances are expressed in terms of the Rayleigh conductivity of an isolated perforation. Consequently, in one other part of the present study, the methodology recently introduced by Laurens et al. (ESAIM, Math. Model. Numer. Anal., vol. 47 (6), 2013, pp. 1691–1712) to obtain sharp bounds for the Rayleigh conductivity has been extended to include the case for which the openings of the perforations on the upper and lower sides of the plate are elliptical in shape. This not only enables the determination of these bounds and of the associated reflection and transmission coefficients for actual plates with tilted perforations but also yields single expressions covering all usual cases of perforations: straight or tilted with a circular or an elliptical cross-section.
On precessing flow in an oblate spheroid of arbitrary eccentricity
Authors: Zhang Keke , Chan Kit H. , Liao Xinhao
Published: March 2014

We consider a homogeneous fluid of viscosity$\nu $confined within an oblate spheroidal cavity of arbitrary eccentricity$\mathcal{E}$marked by the equatorial radius$d$and the polar radius$d \sqrt{1-\mathcal{E}^2}$with$0<\mathcal{E}<1$. The spheroidal container rotates rapidly with an angular velocity${\boldsymbol{\Omega}}_0 $about its symmetry axis and precesses slowly with an angular velocity${\boldsymbol{\Omega}}_p$about an axis that is fixed in space. It is through both topographical and viscous effects that the spheroidal container and the viscous fluid are coupled together, driving precessing flow against viscous dissipation. The precessionally driven flow is characterized by three dimensionless parameters: the shape parameter$\mathcal{E}$, the Ekman number${\mathit{Ek}}=\nu /(d^2 \delimiter "026A30C {\boldsymbol{\Omega}}_0\delimiter "026A30C )$and the Poincaré number${\mathit{Po}}=\pm \delimiter "026A30C {\boldsymbol{\Omega}}_p\delimiter "026A30C / \delimiter "026A30C \boldsymbol{\Omega}_0\delimiter "026A30C $. We derive a time-dependent asymptotic solution for the weakly precessing flow in the mantle frame of reference satisfying the no-slip boundary condition and valid for a spheroidal cavity of arbitrary eccentricity at${\mathit{Ek}}\ll 1$. No prior assumptions about the spatial–temporal structure of the precessing flow are made in the asymptotic analysis. We also carry out direct numerical simulation for both the weakly and the strongly precessing flow in the same frame of reference using a finite-element method that is particularly suitable for non-spherical geometry. A satisfactory agreement between the asymptotic solution and direct numerical simulation is achieved for sufficiently small Ekman and Poincaré numbers. When the nonlinear effect is weak with$\delimiter "026A30C {\mathit{Po}}\delimiter "026A30C \ll 1$, the precessing flow in an oblate spheroid is characterized by an azimuthally travelling wave without having a mean azimuthal flow. Stronger nonlinear effects with increasing$\delimiter "026A30C {\mathit{Po}}\delimiter "026A30C $produce a large-amplitude, time-independent mean azimuthal flow that is always westward in the mantle frame of reference. Implications of the precessionally driven flow for the westward motion observed in the Earth’s fluid core are also discussed.
Coupling of surface water and groundwater nitrate-N dynamics in two permeable agricultural catchments
Authors: MELLANDER P.-E. , MELLAND A. R. , MURPHY P. N. C. , WALL D. P. , SHORTLE G. , JORDAN P.
Published: March 2014

The current study investigated the coupling of groundwater and surface water nitrogen (N) dynamics over 3 years, and considered intensive agricultural land-management influences over this period where the risk of N loss to water was considered high. Groundwater N (as nitrate) was monitored monthly in different strata and zones in four hillslopes, two in each of two agricultural catchments ofc. 10 km2, and stream water N flux was monitored sub-hourly in the catchment outlets. Field nutrient sources were connected to surface waterviagroundwater; the groundwater along hillslopes was seen to be influenced spatially and temporally by management, geology and weather as observed in the concentration variability of nitrate in groundwater. Based on spatio-temporal averages of nitrate-N concentration, groundwater status was considered good (at least below a maximum acceptable concentration (MAC) of 11·3 mg/l). However, zones coincident with land-use change (ploughing and reseeding, typical of a management event in intensive landscapes), showed high spatio-temporal variability in nitrate-N concentration, exceeding the MAC temporarily, before recovering. This spatio-temporal variability highlighted the need for insight into these differences when interpreting groundwater quality data from a limited number of basin-scale sampling points and occasions. In both catchments the 3-year mean nitrate-N concentration in stream water was similar to the spatio-temporal mean concentration in groundwater. The magnitude and variability of loads, however, were more related to changes in annual runoff rather than changes in annual groundwater nitrate-N status. In one wet year, nitrate-N loads exceeded 48 kg/ha from an Arable catchment and 45 kg/ha from a grassland catchment (close to double the loss in a dry year).
Dynamics of bovine intramammary infections due to coagulase-negative staphylococci on four farms
Authors: Bexiga Ricardo , Rato Márcia G. , Lemsaddek Abdelhak , Semedo-Lemsaddek Teresa , Carneiro Carla , Pereira Helena , Mellor Dominic J , Ellis Kathryn A , Vilela Cristina L
Published: March 2014

The objectives of this study were to compare the impact of different coagulase-negative species (CNS) on udder health measured in terms of individual quarter milk somatic cell count (SCC) and duration of intramammary infection, and to get some insight into most likely routes of infection for different CNS species. This longitudinal observational study was performed on four farms that were sampled at 4-week intervals for a total of 12 visits each. Quarters infected with CNS were followed through time with milk samples being submitted for bacteriological culture and SCC determination. PCR amplification of the internal transcribed spacer region and sequencing of the sodA and rpoB genes were used for species allocation. Pulsed-field gel electrophoresis (PFGE) was performed to assess strain identity. The percentage of quarters affected per farm varied between 6 and 35%, with the most frequently isolated CNS species being Staphylococcus epidermidis, followed by Staph. simulans, Staph. chromogenes and Staph. haemolyticus. It was possible to follow 111 intramammary infections due to CNS through time. Duration of infection had a mean of 188 d and was not significantly different between CNS species. Geometric mean quarter SCC overall was 132 000 cells/ml and was also not significantly different between CNS species. Despite the possibility of a different epidemiology of infection, the impact in terms of udder health seems to be similar for different CNS species.
Effects of overmilking and liner type and characteristics on teat tissue in small ruminants
Authors: Alejandro Manuel , Roca Amparo , Romero Gema , Díaz José-Ramón
Published: March 2014

The aim of this work was to study the effect on teat wall thickness and canal length in sheep and goats of overmilking for 2 min (OM+2) and of milking with used (AL; +3000 milkings) and twisted (TL; 45°) liners in sheep and goats, as well as the effect of milking goats with liners designed for sheep (SL, shorter length and diameter than liners for goats). To this end, we performed four experiments in goats and three in sheep, in a Latin square design with two experimental periods. During the experimental period 4 controls were carried out, performing ultrasound scans before and immediately after milking to determine the teat wall thickness (TWT), teat wall area (TWA), teat end area (TEWA) and teat canal length (TCL). OM+2 caused a significant increase in TWT, TWA, TEWA and TCL in goats and in TWA, TEWA and TCL in sheep. Liner features had a strong influence on the variables studied; aged liners caused significant changes in TWT and TCL in goats and in TWT in sheep; twisted liners produced a significant effect on the increase of TWT and TCL in goats, without reaching significance level in sheep; and milking goats with sheep liners led to a significant increase in TWT, TWA, TEWA and TCL. In practice, it is therefore important to avoid overmilking and the use of worn-out liners. It is also necessary to use liners designed for the morphological features of each species, taking special care to carry out periodic liner positioning revisions to ensure the benefits of pulsation on the teat end. Finally, it would be necessary to carry out long-term experiments to study whether the increase in thickness observed in some experiments is sufficient to affect milking efficiency and mammary gland health status.
External possession in Chimwiini
Authors: HENDERSON BRENT
Published: March 2014

Most discussion surrounding external possessors has centered around dative NPs or clitics in Indo-European or Semitic languages and focused on whether or not such structures are derived via movement. This paper examines external possessors in Chimwiini, a Bantu language that lacks datives. It will be shown that while these constructions share certain structural and semantic restrictions with their counterparts in other languages, these properties do not straightforwardly correlate with arguments for a movement or base-generation analysis. This suggests the derivational mechanics of the constructions involved are independent of the semantic restrictions placed on them.
IX.—Water Movements in the Tay Estuary
Authors: West J. R.
Published: March 2014

Synopsis

The present poor understanding of the fundamental mechanisms of estuarine water movement necessitates an empirical or semi-empirical approach to the circulation problem.

The Tay estuary may be considered as a system for which the inputs consist of phenomena of marine and fluvial origin, and the output is the resultant fluid motion. The definition of the boundaries of the system and of the inputs is explained. The functional dependence of fluid motion is examined with respect to the existing knowledge of estuarine circulation and the economic and technological difficulties associated with prototype estuarine investigations. The results of these studies formed the basis for planning a field study of the Tay estuary.

Data collected during the year 1969-70 has permitted the formulation of empirical relationships between parametric forms of the input and output variables. Thus, to a first approximation, the parameters of estuarine water motion can be predicted for particular antecedent input conditions.
XIII.—The Fisheries of the Forth–Tay Estuaries
Authors: Thomas H. J. , Saville A.
Published: March 2014

Synopsis

The most valuable species are Nephrops, salmon, haddock, lobster and sprat. Demersal fish, haddock, whiting, cod, plaice and lemon sole, are mainly taken by seine-netters and light trawlers from 40 to 70 ft overall length. Landings of cod and lemon sole have declined, as has fishing effort. The estuarine environment is especially important for plaice and cod, which spend their early life in coastal waters. Pelagic fish, herring, sprat and mackerel, are unimportant but occasionally pair-trawling for sprats occupies up to 75 boats. Nephrops trawlers, from 40 to 55 ft, fish mainly west of May Island. The Nephrops stocks are heavily exploited. Creel fishing for lobster and crab supports 85 boats. The lobster stocks are intensively fished and landings have decreased. Periwinkles and mussels are gathered but shrimps, though present, are not exploited. Landings of salmon and sea trout, mainly by net and coble from the estuaries, are important chiefly in the Tay. The fisheries have changed dramatically in the past century. Those for herring, oysters and queens have ceased whilst new fisheries have developed for Nephrops and sprat.
The Distribution of Bottom Sediments in Loch Leven, Kinross
Authors: Calvert S. E.
Published: March 2014

Synopsis

The sediments of shallow and deep water areas of Loch Leven are, respectively, medium to very fine-grained sands and silty clays (muds). The largest area of more or less uniform sediment type (sands) occurs on the north-eastern shelf. The sediments with the finest grain size are found in an area to the south and east of Castle Island and Reed Bower. Here, the median grain size is less than 4 microns. The amount of sand in a sediment is very highly correlated with the median grain size of the sediment and may therefore most usefully be used to describe the general distribution of sediments in the loch. The distribution of organic carbon in the loch sediments is largely confined to deep-water areas. The southern deep area is more organic rich than the northern deep area. The amount of organic carbon in a sediment is positively correlated with the amounts of clay and silt in the sediment.