bluuebunny/crossref_metadata_2025 huggingface dataset:
Large Deviations for Brownian Intersection Measures
Authors: König Wolfgang , Mukherjee Chiranjib
Published: May 2012

We consider p independent Brownian motions in
\input amssym ${\Bbb R}^d$. We assume that p ≥ 2 and p (d − 2) < d. Let ℓt denote the intersection measure of the p paths by time t, i.e., the random measure on \input amssym ${\Bbb R}^d$
that assigns to any measurable set \input amssym $A \subset {\Bbb R}^d$
the amount of intersection local time of the motions spent in A by time t. Earlier results of X. Chen derived the logarithmic asymptotics of the upper tails of the total mass \input amssym $\ell _t \left({{\Bbb R}^d } \right)$
as t → ∞. In this paper, we derive a large‐deviation principle for the normalized intersection measure t−pℓt on the set of positive measures on some open bounded set \input amssym $B \subset {\Bbb R}^d$
as t → ∞ before exiting B. The rate function is explicit and gives some rigorous meaning, in this asymptotic regime, to the understanding that the intersection measure is the pointwise product of the densities of the normalized occupation times measures of the p motions. Our proof makes the classical Donsker‐Varadhan principle for the latter applicable to the intersection measure.

A second version of our principle is proved for the motions observed until the individual exit times from B, conditional on a large total mass in some compact set
$U \subset B$. This extends earlier studies on the intersection measure by König and Mörters. © 2012 Wiley Periodicals, Inc.
Divalent Europium Nanocrystals: Controllable Synthesis, Properties, and Applications
Authors: Wang Chuanxi , Xu Lin , Li Xiangwei , Lin Quan
Published: May 2012

Magnetic and luminescent bifunctional divalent europium nanocrystals (Eu2+ NCs) are a promising class of novel advanced materials that have various applications in magneto‐optic devices, catalysis, bioimaging, and solar cells. In the past few decades, much work has been carried out to study the synthesis, properties, and applications of Eu2+ NCs. The aim of this Minireview is to present the progress in preparing Eu2+ NCs based on the reported research, by describing the advantages and disadvantages of the synthesis methods. The morphologies and size are controlled through adjusting the experimental conditions. Eu2+ NCs show superior magnetic and luminescence properties simultaneously. Self‐assembly and doping with other ions are important routes to improve their magnetic and luminescence properties. Their applications in magneto‐optic devices are discussed. Some difficulties and challenges in the fabrication of Eu2+ NCs are discussed, such as water‐soluble Eu2+ NCs and tunable luminescence in the whole visible region.
Calixarene‐Based Surfactants: Conformational‐Dependent Solvation Shells for the Alkyl Chains
Authors: Basílio Nuno , Garcia‐Rio Luis
Published: May 2012

Thermodynamic parameters obtained from studying the micellization of amphiphilic p‐sulfonatocalix[n]arenes were correlated with the alkyl chain length and with the number of monomeric units (n) in the calix[n]arene structure. The micellization Gibbs free energy (Δ${G{{{\rm o}\hfill \atop {\rm M}\hfill}}}$) becomes more negative upon increasing the alkyl chain length of the p‐sulfonatocalix[4]arene. This is in agreement with the trend generally observed for other surfactants. However, the Δ${G{{{\rm o}\hfill \atop {\rm M}\hfill}}}$ value for transferring one CH2 group from the bulk aqueous medium to the micelle [Δ${G{{{\rm o}\hfill \atop {\rm M}\hfill}}}$(CH2)] is lower than the value generally observed for single‐chain surfactants, suggesting the existence of intramolecular interactions between the alkyl chains of the free unimers. On the other hand, the critical micelle concentration (cmc; per alkyl chain unit) increased with the increasing number of monomeric units. These results are explained on the basis of the conformation adopted by the calixarene in the bulk solution. The calix[4]arene derivatives are preorganized into the cone conformation, which is favorable for the formation of globular aggregates. The calix[6]arene and calix[8]arene derivatives do not adopt cone conformations. Changing these conformations to the more favorable cone conformer in the aggregates implies an energetic cost that contributes to making Δ${G{{{\rm o}\hfill \atop {\rm M}\hfill}}}$ less efficient. In the case of the calix[6]arene derivative this energetic cost is enthalpic, whereas in the case of the octamer it is both enthalpic and entropic. Both the Δ${G{{{\rm o}\hfill \atop {\rm M}\hfill}}}$(CH2) value and the change in heat capacity (ΔC${{\rm p}{{{\rm o}\hfill \atop {\rm M}\hfill}}}$) seem to indicate that for the cone calix[4]arene derivatives all alkyl chains are solvated by the same hydration shell, whereas in the case of the highly flexible calix[8]arene derivative each alkyl chain is individually hydrated.
Structural Characteristics of Graphane‐Type C and BN Nanostructures by Periodic Local MP2 Approach
Authors: Tanskanen Jukka T. , Maschio Lorenzo , Karttunen Antti J. , Linnolahti Mikko , Pakkanen Tapani A.
Published: May 2012

The structural characteristics of fully‐hydrogenated carbon and boron nitride mono‐ and multilayer slabs, together with nanotubes derived from the slabs, are investigated mainly by means of periodic local second‐order Møller–Plesset perturbation (LMP2) calculations and the results are compared with Hartree–Fock (HF), density functional theory (DFT), and dispersion function‐augmented DFT (DFT‐D) obtained ones. The investigated systems are structurally analogous to (111) and (110) slabs of diamond, where the hydrogenated (111) slab of diamond corresponds to the experimentally known graphane. Multilayering of monolayers and nanotubes is energetically favorable at the LMP2 level for both C and BN, while HF and DFT are not able to reproduce this behavior for CH systems. The work highlights the importance of utilizing methods capable of properly describing weak interactions in the investigation of dispersively‐bound systems such as the multilayered graphanes and the corresponding nanotubes.
The Nature of Chemical Bonds from PNOF5 Calculations
Authors: Matxain Jon M. , Piris Mario , Uranga Jon , Lopez Xabier , Merino Gabriel , Ugalde Jesus M.
Published: May 2012

Natural orbital functional theory (NOFT) is used for the first time in the analysis of different types of chemical bonds. Concretely, the Piris natural orbital functional PNOF5 is used. It provides a localization scheme that yields an orbital picture which agrees very well with the empirical valence shell electron pair repulsion theory (VSEPR) and Bent’s rule, as well as with other theoretical pictures provided by valence bond (VB) or linear combination of atomic orbitals–molecular orbital (LCAO‐MO) methods. In this context, PNOF5 provides a novel tool for chemical bond analysis. In this work, PNOF5 is applied to selected molecules that have ionic, polar covalent, covalent, multiple (σ and π), 3c–2e, and 3c–4e bonds.
Spiral Intramolecular Charge Transfer and Large First Hyperpolarizability in Möbius Cyclacenes: New Insight into the Localized π Electrons
Authors: Zhong Rong‐Lin , Xu Hong‐Liang , Su Zhong‐Min , Li Zhi‐Ru , Sun Shi‐Ling , Qiu Yong‐Qing
Published: May 2012

Much effort has been devoted to investigating the unusual properties of the π electrons in Möbius cyclacenes, which are localized in a special region. However, the localized π electrons are a disadvantage for applications in optoelectronics, because intramolecular charge transfer is limited. This raises the question of how the intramolecular charge transfer of a Möbius cyclacene with clearly localized π electrons can be enhanced. To this end, [8]Möbius cyclacene ([8]MC) is used as a conjugated bridge in a donor–π‐conjugated bridge–acceptor (D–π–A) system, and NH2‐6‐[8]MC‐10‐NO2 exhibits a fascinating spiral charge‐transfer transition character that results in a significant difference in dipole moments Δμ between the ground state and the crucial excited state. The Δμ value of 6.832 D for NH2‐6‐[8]MC‐10‐NO2 is clearly larger than that of 0.209 D for [8]MC. Correspondingly, the first hyperpolarizability of NH2‐6‐[8]MC‐10‐NO2 of 12 467 a.u. is dramatically larger than that of 261 a.u. for [8]MC. Thus, constructing a D–π–A framework is an effective strategy to induce greater spiral intramolecular charge transfer in MC although the π electrons are localized in a special region. This new insight into the properties of π electrons in Möbius cyclacenes may provide valuable information for their applications in optoelectronics.
Polypyridyl Complexes of Ruthenium(II): Stabilization of G‐quadruplex DNA and Inhibition of Telomerase Activity
Authors: Liu Du , Liu Yanan , Wang Chuan , Shi Shuo , Sun Dongdong , Gao Feng , Zhang Qianling , Liu Jie
Published: May 2012

Two ruthenium(II) complexes [Ru(phen)2(tip)](ClO4)2 (1) and [Ru(bpy)2(tip)](ClO4)2 (2; phen=1,10‐phenanthroline, bpy=2,2’‐bipyridine, tip=2‐thiophenimidazo[4,5‐f][1,10]phenanthroline) were synthesized and characterized by elemental analysis, 1H NMR spectroscopy, and electrospray ionization‐mass spectrometry to explore the role of metal complexes as novel telomeric quadruplex stabilizers. The different quadruplex binding properties of these compounds were evaluated by absorption and emission analyses, circular dichroism spectroscopy, fluorescence resonance energy transfer (FRET) melting assay, NMR spectroscopy, and molecular modeling. The results show that both complexes can well induce and stabilize different G‐quadruplex structures using a 1:1 [quadruplex]/[complex] binding mode ratio. Complex 1 exhibits higher interaction ability at 1.43×106 M−1 binding affinity and superior G‐quadruplex selectivity over duplex DNA through multiple interaction (mainly intercalating) with the G‐quadruplex at the 3’‐terminal face. Furthermore, polymerase chain reaction (PCR)‐stop assay, electrophoretic mobility shift assay, telomerase repeat amplification protocol, and MTT assay demonstrate that complex 1 not only can stabilize dimer forms of the G‐quadruplex at low concentrations but also exhibit better inhibitory activity for telomerase and cancer cells. The results suggest that complex 1 may be a potential telomerase inhibitor for cancer chemotherapy.
Investigation of Copper Corrosion Inhibition with Frequency‐Dependent Alternating‐Current Scanning Electrochemical Microscopy
Authors: Santana Juan José , Pähler Maike , Schuhmann Wolfgang , Souto Ricardo M.
Published: May 2012

Alternating current scanning electrochemical microscopy (AC‐SECM) is used to investigate the inhibition of copper corrosion by four potential inhibitors, namely benzotriazole (BTAH), 5‐methyl‐benzotriazole (MBTAH), 2‐mercaptobenzimidazole (MBI), and ethyl xanthate (EX). It is shown that the formation of inhibitor films on the metal can be followed from the decrease of the substrate’s local electrochemical activity associated with the formation of inhibitor‐containing surface layers. Sensitive imaging can be performed that accounts for changes in electrochemical activity of the modified surfaces, as well as for their corrosive attack from the environment. AC‐SECM is shown to be a powerful technique for the investigation of corrosion processes.
An Affective–Cognitive Processing Model of Post‐Traumatic Growth
Authors: Joseph Stephen , Murphy David , Regel Stephen
Published: May 2012

A topic that has begun to attract interest from clinical psychologists and psychotherapists is post‐traumatic growth. First, we provide a general overview of the field, setting out the historical development, main concepts, measurement issues and research findings. Second, we review evidence showing that the relationship between post‐traumatic stress and post‐traumatic growth is likely curvilinear. Third, a new affective–cognitive processing model of post‐traumatic growth will be introduced in which post‐traumatic stress is understood to be the engine of post‐traumatic growth. Fourth, points of clinical intervention are described showing the ways in which therapists can facilitate post‐traumatic growth. Copyright © 2012 John Wiley & Sons, Ltd.

Key Practitioner Message

No one approach to the treatment of trauma is able to help all people all of the time.

Post‐traumatic growth emerges out of satisfactory affective–cognitive processing.

A common‐factor approach that recognizes that there are many points of therapeutic intervention is described.
Microbial Nanowires: A New Paradigm for Biological Electron Transfer and Bioelectronics
Authors: Malvankar Nikhil S. , Lovley Derek R.
Published: May 2012

The discovery that Geobacter sulfurreducens can produce protein filaments with metallic‐like conductivity, known as microbial nanowires, that facilitate long‐range electron transport is a paradigm shift in biological electron transfer and has important implications for biogeochemistry, microbial ecology, and the emerging field of bioelectronics. Although filaments in a wide diversity of microorganisms have been called microbial nanowires, the type IV pili of G. sulfurreducens and G. metallireducens are the only filaments that have been shown to be required for extracellular electron transport to extracellular electron acceptors or for conduction of electrons through biofilms. Studies of G. sulfurreducens pili preparations and intact biofilms under physiologically relevant conditions have provided multiple lines of evidence for metallic‐like conduction along the length of pili and for the possibility of pili networks to confer high conductivity within biofilms. This mechanism of electron conduction contrasts with the previously known mechanism for biological electron transfer via electron tunneling or hopping between closely associated molecules, a strategy unlikely to be well adapted for long‐range electron transport outside the cell. In addition to promoting electron exchange with abiotic electron acceptors, microbial nanowires have recently been shown to be involved in direct interspecies electron transfer between syntrophic partners. An improved understanding of the mechanisms for metallic‐like conductivity in microbial nanowires, as well as engineering microorganisms with desirable catalytic abilities with nanowires, could lead to new applications in microbial electrosynthesis and bioelectronics.
On Electron Transport through Geobacter Biofilms
Authors: Bond Daniel R. , Strycharz‐Glaven Sarah M. , Tender Leonard M. , Torres César I.
Published: May 2012

Geobacter spp. can form a biofilm that is more than 20 μm thick on an anode surface by utilizing the anode as a terminal respiratory electron acceptor. Just how microbes transport electrons through a thick biofilm and across the biofilm/anode interface, and what determines the upper limit to biofilm thickness and catalytic activity (i.e., current, the rate at which electrons are transferred to the anode), are fundamental questions attracting substantial attention. A significant body of experimental evidence suggests that electrons are transferred from individual cells through a network of cytochromes associated with cell outer membranes, within extracellular polymeric substances, and along pili. Here, we describe what is known about this extracellular electron transfer process, referred to as electron superexchange, and its proposed role in biofilm anode respiration. Superexchange is able to account for many different types of experimental results, as well as for the upper limit to biofilm thickness and catalytic activity that Geobacter biofilm anodes can achieve.
Robust smart‐card‐based remote user password authentication scheme
Authors: Chen Bae‐Ling , Kuo Wen‐Chung , Wuu Lih‐Chyau
Published: May 2012

Smart‐card‐based remote user password authentication schemes are commonly used for providing authorized users a secure method for remotely accessing resources over insecure networks. In 2009, Xu et al. proposed a smart‐card‐based password authentication scheme. They claimed their scheme can withstand attacks when the information stored on the smart card is disclosed. Recently, Sood et al. and Song discovered that the smart‐card‐based password authentication scheme of Xu et al. is vulnerable to impersonation and internal attacks. They then proposed their respective improved schemes. However, we found that there are still flaws in their schemes: the scheme of Sood et al. does not achieve mutual authentication and the secret key in the login phase of Song's scheme is permanent and thus vulnerable to stolen‐smart‐card and off‐line guessing attacks. In this paper, we will propose an improved and efficient smart‐card‐based password authentication and key agreement scheme. According to our analysis, the proposed scheme not only maintains the original secret requirement but also achieves mutual authentication and withstands the stolen‐smart‐card attack. Copyright © 2012 John Wiley & Sons, Ltd.
Saccharin pre‐exposure enhances appetitive flavor learning in pre‐weanling rats
Authors: Swithers Susan E. , Ogden Sean B. , Laboy Alycia F. , Davidson T.L.
Published: May 2012

In adult rats, data suggest that consumption of sweet tastes that do not deliver anticipated caloric consequences using high‐intensity, non‐caloric sweeteners, such as saccharin, interferes with learned relations that may contribute to energy balance. The goal of the present study was to assess the development of learning about sweet taste and calories by assessing whether pre‐exposure to saccharin solutions reduces cue competition in pre‐weanling rats. The results demonstrated that rats pre‐exposed to saccharin and then trained with a novel grape flavor paired with a glucose‐sweetened solution consumed more of the novel grape flavor presented alone than rats that had been pre‐exposed to saccharin and given the grape flavor paired with water alone. No differences in intake of the novel grape flavor were observed in groups given pre‐exposure to water or glucose solutions. Thus, by 15 days of age, rats appear to have established an association between sweet tastes and calories, and this association can be weakened by exposure to saccharin. © 2012 Wiley Periodicals,Inc. Dev Psychobiol 54: 818–824, 2012
Flexibility and applicability of β‐expectation tolerance interval approach to assess the fitness of purpose of pharmaceutical analytical methods
Authors: Bouabidi A. , Talbi M. , Bourichi H. , Bouklouze A. , El Karbane M. , Boulanger B. , Brik Y. , Hubert Ph. , Rozet E.
Published: May 2012

An innovative versatile strategy using Total Error has been proposed to decide about the method's validity that controls the risk of accepting an unsuitable assay together with the ability to predict the reliability of future results. This strategy is based on the simultaneous combination of systematic (bias) and random (imprecision) error of analytical methods. Using validation standards, both types of error are combined through the use of a prediction interval or β‐expectation tolerance interval. Finally, an accuracy profile is built by connecting, on one hand all the upper tolerance limits, and on the other hand all the lower tolerance limits. This profile combined with pre‐specified acceptance limits allows the evaluation of the validity of any quantitative analytical method and thus their fitness for their intended purpose.

In this work, the approach of accuracy profile was evaluated on several types of analytical methods encountered in the pharmaceutical industrial field and also covering different pharmaceutical matrices. The four studied examples depicted the flexibility and applicability of this approach for different matrices ranging from tablets to syrups, different techniques such as liquid chromatography, or UV spectrophotometry, and for different categories of assays commonly encountered in the pharmaceutical industry i.e. content assays, dissolution assays, and quantitative impurity assays. The accuracy profile approach assesses the fitness of purpose of these methods for their future routine application. It also allows the selection of the most suitable calibration curve, the adequate evaluation of a potential matrix effect and propose efficient solution and the correct definition of the limits of quantification of the studied analytical procedures. Copyright © 2012 John Wiley & Sons, Ltd.
Capillary Electrophoresis Coupled with Electrochemiluminescence for the Facile Separation and Determination of Salbutamol and Clenbuterol in Urine
Authors: Bao Yi , Yang Fan , Yang Xiurong
Published: May 2012

A capillary electrophoresis coupled with tris(2,2′‐bipyridyl) ruthenium(II) (Ru(bpy)32+) electrochemiluminescence detection system was developed to determine salbutamol and clenbuterol in urine. Some factors that affected the performances of separation and detection were investigated. Under the optimized conditions, one single quantitative analysis of salbutamol and clenbuterol was achieved at a separation voltage of 15 kV within 9 min, and the LODs (S/N=3) and LOQs (S/N=10) of salbutamol and clenbuterol were 8.43×10−8 mol/L, 2.61×10−7 mol/L and 2.73×10−7 mol/L, 8.21×10−7 mol/L, respectively. The recovery obtained from the analysis of spiked urine samples was between 88.6 % and 104.7 % with RSDs lower than 6.70 %. The method was successfully applied to determine salbutamol and clenbuterol in urine samples.
Structural Characterization of Graphene Nanosheets for Miniaturization of Potentiometric Urea Lipid Film Based Biosensors
Authors: Nikoleli Georgia‐Paraskevi , Israr Muhammad Q. , Tzamtzis Nikolaos , Nikolelis Dimitrios P. , Willander Magnus , Psaroudakis Nikolas
Published: May 2012

The present article describes a miniaturized potentiometric urea lipid film based biosensor on graphene nanosheets. Structural characterization of graphene nanosheets for miniaturization of potentiometric urea lipid film based biosensors have been studied through atomic force microscopy (AFM) and transmission electron microscopy (TEM) measurements. UV‐Vis and Fourrier transform IR (FTIR) spectroscopy have been utilized to study the pre‐ and postconjugated surfaces of graphene nanosheets. The presented potentiometric urea biosensor exhibits good reproducibility, reusability, selectivity, rapid response times (∼4 s), long shelf life and high sensitivity of ca. 70 mV/decade over the urea logarithmic concentration range from 1×10−6 M to 1×10−3 M.
A correction for balancing discontinuous bed slopes in two‐dimensional smoothed particle hydrodynamics shallow water modeling
Authors: Vacondio R. , Rogers B. D. , Stansby P. K. , Mignosa P.
Published: May 2012

In this paper, a smoothed particle hydrodynamics (SPH) numerical model for the shallow water equations (SWEs) with bed slope source term balancing is presented. The solution of the SWEs using SPH is attractive being a conservative, mesh‐free, automatically adaptive method without special treatment for wet‐dry interfaces. Recently, the capability of the SPH–SWEs numerical scheme with shock capturing and general boundary conditions has been used for predicting practical flooding problems. The balance between the bed slope source term and fluxes in shallow water models is desirable for reliable simulations of flooding over bathymetries where discontinuities are present and has received some attention in the framework of Finite Volume Eulerian models. The imbalance because of the source term resulting from the calculation of the the water depth is eradicated by means of a corrected mass, which is able to remove the error introduced by a bottom discontinuity. Two different discretizations of the momentum equation are presented herein: the first one is based on the variational formulation of the SWEs in order to obtain a fully conservative formulation, whereas the second one is obtained using a non‐conservative form of the free‐surface elevation gradient. In both formulations, a variable smoothing length is considered. Results are presented demonstrating the corrections preserve still water in the vicinity of either 1D or 2D bed discontinuities and provide close agreement with 1D analytical solutions for rapidly varying flows over step changes in the bed. The method is finally applied to 2D dam break flow over a square obstacle where the balanced formulation improves the agreement with experimental measurements of the free surface. Copyright © 2012 John Wiley & Sons, Ltd.
Leukemia/lymphoma‐related factor regulates oligodendrocyte lineage cell differentiation in developing white matter
Authors: Dobson Nicole R. , Moore Ryan T. , Tobin Jennifer E. , Armstrong Regina C.
Published: May 2012

Leukemia/lymphoma‐related factor (LRF) is a zinc‐finger transcription factor that regulates differentiation and oncogenesis in multiple tissues and cell lineages. The potential role for LRF in cells of the CNS has not been examined to date. This study shows prominent nuclear expression of LRF in diverse neuronal populations and in oligodendrocytes. We focused on examining the function of LRF during the transition from oligodendrocyte progenitor (OP) to mature oligodendrocyte that is associated with myelination in the postnatal spinal cord. During spinal cord myelination, LRF is expressed in only a minority of OP cells whereas most mature oligodendrocytes exhibited nuclear LRF immunoreactivity. Mice with floxed alleles of the Zbtb7a gene, which encodes for LRF protein, were used for in vivo analysis of LRF function. Lentiviral driven Cre recombinase inactivation of LRF at postnatal day 7 reduced the proportion of OP cells that differentiated into mature oligodendrocytes by postnatal day 28. Astrocyte populations were not altered by LRF deletion in the same tissues. These results indicate that LRF deletion reduces differentiation within the oligodendrocyte lineage and does not alter OP lineage choice. In vitro analysis confirmed a specific effect of LRF on OP differentiation. In neonatal OP cultures, RNA interference targeting LRF inhibited OP differentiation while LRF transduction was sufficient to induce differentiation into oligodendrocytes. These results support a critical role for LRF in transcriptional control of differentiation in oligodendrocyte lineage cells during developmental myelination in the CNS. © 2012 Wiley Periodicals, Inc.
Interaction between intestinal dendritic cells and bacteria translocated from the gut in rats with cirrhosis
Authors: Muñoz Leticia , Borrero María José , Ubeda María , Lario Margaret , Díaz David , Francés Rubén , Monserrat Jorge , Pastor Óscar , Aguado-Fraile Elia , Such José , Álvarez-Mon Melchor , Albillos Agustín
Published: May 2012

Cirrhosis with ascites is associated with a high rate of gut bacterial translocation (GBT) and spontaneous bacterial infections of enteric origin. We addressed the activation state and role of intestinal dendritic cells (DCs) in experimental ascitic cirrhosis and their relationship with GBT. Cirrhosis with ascites was CCl4 induced in rats. To examine their activation state and functions, DCs (CD103+RT1B+CD3−CD45RA−) were isolated from the intestinal lamina propria and mesenteric lymph nodes (MLNs), and the following parameters were determined by flow cytometry: surface antigen expression; spontaneous or lipopolysaccharide-stimulated tumor necrosis factor alpha (TNF-α) production; and

in vitro

capacity to phagocytose latex beads and to migrate toward the chemokine (C-C motif) ligand 21. GBT was defined as the growth of bacteria in MLNs culture. Bacterial DNA (Bact-DNA) in MLNs was identified by polymerase chain reaction. In rats with Bact-DNA in MLNs without GBT, intestinal and MLNs CD103+-DCs showed features of activation, expansion of the proinflammatory CD4+-DC subpopulation, augmented TNF-α production, and increased phagocytic and migratory capacities. In contrast, in rats with GBT, CD103+-DCs showed the absence of an activated phenotype, lowered TNF-α production, and relatively deficient phagocytosis and migration capacities. The CD103+-DC of rats without Bact-DNA in MLNs or GBT were similar to controls. In cirrhotic rats, bowel decontamination with antibiotics eliminated Bact-DNA in MLNs and GBT, normalized the activation state and functions of CD103+-DCs, and increased their TNF-α production.

Conclusion :

In experimental cirrhosis with ascites, continuous pressure of gut bacteria shapes the phenotypic and functional profile of intestinal DCs to produce effects that range from their activation and enhanced functions to their exhaustion and tolerance.
Estimate of the alpha parameter in an oat crop under rain‐fed conditions
Authors: Carmona Facundo , Rivas Raúl , Caselles Vicente
Published: May 2012

In this article, we estimated the alpha parameter of the Priestley–Taylor model under rain‐fed conditions. This study was conducted in an oat crop, from 7 September to 22 October 2009, in a region of subhumid plains (Tandil, Argentina). An energy balance station was installed within the experimental field to monitor its development. The alpha parameter value obtained was 1.41 ± 0.01, which led to an overestimation of the evapotranspiration of just 2% and a relative error in estimating evapotranspiration of 8%. The results suggest that the alpha parameter obtained is adequate in estimating the evapotranspiration of oat crops or similar crops in subhumid plains of Buenos Aires, Argentina. Copyright © 2012 John Wiley & Sons, Ltd.
The European Flood Alert System and the communication, perception, and use of ensemble predictions for operational flood risk management
Authors: Demeritt David , Nobert Sebastien , Cloke Hannah L. , Pappenberger Florian
Published: May 2012

Although ensemble prediction systems (EPS) are increasingly promoted as the scientific state‐of‐the‐art for operational flood forecasting, the communication, perception, and use of the resulting alerts have received much less attention. Using a variety of qualitative research methods, including direct user feedback at training workshops, participant observation during site visits to 25 forecasting centres across Europe, and in‐depth interviews with 69 forecasters, civil protection officials, and policy makers involved in operational flood risk management in 17 European countries, this article discusses the perception, communication, and use of European Flood Alert System (EFAS) alerts in operational flood management. In particular, this article describes how the design of EFAS alerts has evolved in response to user feedback and desires for a hydrographic‐like way of visualizing EFAS outputs. It also documents a variety of forecaster perceptions about the value and skill of EFAS forecasts and the best way of using them to inform operational decision making. EFAS flood alerts were generally welcomed by flood forecasters as a sort of ‘pre‐alert’ to spur greater internal vigilance. In most cases, however, they did not lead, by themselves, to further preparatory action or to earlier warnings to the public or emergency services. Their hesitancy to act in response to medium‐term, probabilistic alerts highlights some wider institutional obstacles to the hopes in the research community that EPS will be readily embraced by operational forecasters and lead to immediate improvements in flood incident management. The EFAS experience offers lessons for other hydrological services seeking to implement EPS operationally for flood forecasting and warning. Copyright © 2012 John Wiley & Sons, Ltd.
Tracing sediment sources in a tropical highland catchment of central Mexico by using conventional and alternative fingerprinting methods
Authors: Evrard Olivier , Poulenard Jérôme , Némery Julien , Ayrault Sophie , Gratiot Nicolas , Duvert Clément , Prat Christian , Lefèvre Irène , Bonté Philippe , Esteves Michel
Published: May 2012

Land degradation is intense in tropical regions where it causes for instance a decline in soil fertility and reservoir siltation. Two fingerprinting approaches (i.e. the conventional approach based on radionuclide and geochemical concentrations and the alternative diffuse reflectance infrared Fourier transform spectroscopy method) were conducted independently to outline the sources delivering sediment to the river network draining into the Cointzio reservoir, in Mexican tropical highlands. This study was conducted between May and October in 2009 in subcatchments representative of the different environments supplying sediment to the river network. Overall, Cointzio catchment is characterized by very altered soils and the dominance of Andisols and Acrisols. Both fingerprinting methods provided very similar results regarding the origin of sediment in Huertitas subcatchment (dominated by Acrisols) where the bulk of sediment was supplied by gullies. In contrast, in La Cortina subcatchment dominated by Andisols, the bulk of sediment was supplied by cropland. Sediment originating from Potrerillos subcatchment characterized by a mix of Acrisols and Andisols was supplied in variable proportions by both gullies and rangeland/cropland. In this latter subcatchment, results provided by both fingerprinting methods were very variable. Our results outline the need to take the organic carbon content of soils into account and the difficulty to use geochemical properties to fingerprint sediment in very altered volcanic catchments. However, combining our fingerprinting results with sediment export data provided a way of prioritizing the implementation of erosion control measures to mitigate sediment supply to the Cointzio reservoir supplying drinking water to Morelia city. Copyright © 2012 John Wiley & Sons, Ltd.
Three‐dimensional polycaprolactone scaffold‐conjugated bone morphogenetic protein‐2 promotes cartilage regeneration from primary chondrocytes in vitro and in vivo without accelerated endochondral ossification
Authors: Jeong Claire G. , Zhang Huina , Hollister Scott J.
Published: May 2012

As articular cartilage is avascular, and mature chondrocytes do not proliferate, cartilage lesions have a limited capacity for regeneration after severe damage. The treatment of such damage has been challenging due to the limited availability of autologous healthy cartilage and lengthy and expensive cell isolation and expansion procedures. Hence, the use of bone morphogenetic protein‐2 (BMP‐2), a potent regulator of chondrogenic expression, has received considerable attention in cartilage and osteochondral tissue engineering. However, the exact role of BMP‐2 in cartilage repair has been postulated to promote both cartilage formation and subsequent cartilage degradation through hypertrophy and endochondral ossification. Furthermore, it is likely that the manner in which BMP‐2 is presented to chondrocytes will influence the physiologic pathway (repair vs. degeneration). This study investigates the relative influence of BMP‐2 on cartilage matrix and potential subsequent bone matrix production using primary chondrocytes seeded on designed 3D polycaprolactone (PCL) scaffolds with chemically conjugated BMP‐2. The results show that chemically conjugated BMP‐2 PCL scaffolds can promote significantly greater cartilage regeneration from seeded chondrocytes both in vitro and in vivo compared with untreated scaffolds. Furthermore, our results demonstrate that the conjugated BMP‐2 does not particularly accelerate endochondral ossification even in a readily permissible and highly vascular in vivo environment compared with untreated PCL scaffolds. This study not only reveals the potential use of the BMP‐2 conjugation delivery method for enhanced cartilage tissue formation but also gives new insights for the effects of conjugated BMP‐2 on cartilage regeneration and osteochondral ossification. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2012.
Fabrication and characterization of three‐dimensional electrospun scaffolds for bone tissue engineering
Authors: Andric Tea , Wright Lee D. , Taylor Brittany L. , Freeman Joseph W.
Published: May 2012

When traumatic injury, tumor removal, or disease results in significant bone loss, reconstructive surgery is required. Bone grafts are used in orthopedic reconstructive procedures to provide mechanical support and promote bone regeneration. In this study, we applied a heat sintering technique to fabricate 3D electrospun scaffolds that were used to evaluate effects of mineralization and fiber orientation on scaffold strength. We electrospun PLLA/gelatin scaffolds with a layer of PDLA and heat sintered them into three‐dimensional cylindrical scaffolds. Scaffolds were mineralized by incubation in 10× simulated body fluid for 6, 24, and 48 h to evaluate the effect of mineralization on scaffolds compressive mechanical properties. The effects of heat sintering hydroxyapatite (HA) microparticles directly to the scaffolds on mineral deposition, distribution and mechanical properties of the scaffolds were also evaluated. We found that orientation of the fibers had little effect on the compressive mechanical properties of the scaffolds. However, increasing the mineralization times resulted in an increase in compressive mechanical properties. Also, the direct addition of HA microparticles had no effect on the scaffold mechanical properties, but had a significant effect on the mineral deposition on PLLA/gelatin scaffolds. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.
In situ crosslinkable heparin‐containing poly(ethylene glycol) hydrogels for sustained anticoagulant release
Authors: Baldwin Aaron D. , Robinson Karyn G. , Militar Jaimee L. , Derby Christopher D. , Kiick Kristi L. , Akins Robert E.
Published: May 2012

Low‐molecular weight heparin (LMWH) is widely used in anticoagulation therapies and for the prevention of thrombosis. LMWH is administered by subcutaneous injection usually once or twice per day. This frequent and invasive delivery modality leads to compliance issues for individuals on prolonged therapeutic courses, particularly pediatric patients. Here, we report a long‐term delivery method for LMWH via subcutaneous injection of long‐lasting hydrogels. LMWH is modified with reactive maleimide groups so that it can be crosslinked into continuous networks with four‐arm thiolated poly(ethylene glycol) (PEG‐SH). Maleimide‐modified LMWH (Mal‐LMWH) retains bioactivity as indicated by prolonged coagulation time. Hydrogels comprising PEG‐SH and Mal‐LMWH degrade via hydrolysis, releasing bioactive LMWH by first‐order kinetics with little initial burst release. Separately dissolved Mal‐LMWH and PEG‐SH solutions were co‐injected subcutaneously in New Zealand White rabbits. The injected solutions successfully formed hydrogels in situ and released LMWH as measured via chromogenic assays on plasma samples, with accumulation of LMWH occurring at day 2 and rising to near‐therapeutic dose equivalency by day 5. These results demonstrate the feasibility of using LMWH‐containing, crosslinked hydrogels for sustained and controlled release of anticoagulants. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.
In vitro and in vivo toxicity of rinsed and aged nanocellulose–polypyrrole composites
Authors: Ferraz Natalia , Strømme Maria , Fellström Bengt , Pradhan Sulena , Nyholm Leif , Mihranyan Albert
Published: May 2012

Novel composites of nanocellulose and the conducting polymer polypyrrole (PPy) are herein suggested as potential candidates for active ion‐extraction membranes in electrochemically controlled hemodialysis. This study has defined processing parameters to obtain a biocompatible nanocellulose‐PPy composite, and for the first time, the effect of the composite aging on cell viability has been studied. The influence of rinsing and extraction process steps, as well as aging under different conditions (i.e. in air, at –20°C and in argon), on the electroactivity and cytotoxicity of a PPy‐nanocellulose composite has been investigated. The biocompatibility evaluation was based on indirect toxicity assays with fibroblasts and monocyte cell lines and an acute toxicity test in mice, while the electroactivity was evaluated by cyclic voltammetry experiments. The as‐prepared composite did not induce any cytotoxic response in vitro or in vivo. Extensive rinsing and 48 h incubation in biological buffer previous to the preparation of the culture medium extracts were, however, necessary to obtain a noncytotoxic composite. The as‐prepared composite was also found to exhibit acceptable electrochemical performance, which was retained upon 4 weeks storage in argon atmosphere. It was shown that aging of the composite had a negative effect on biocompatibility, regardless of the storage condition. Thus, to allow for longtime storage of electroactive nanocellulose‐PPy hemodialysis membranes, the degradation of PPy upon storage must be controlled. The present results show that the biocompatibility of PPy composites depends on the rinsing and pretreatment of the composite material as well as the aging of the material. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2012.
Orthopedic implant cobalt‐alloy particles produce greater toxicity and inflammatory cytokines than titanium alloy and zirconium alloy‐based particlesin vitro, in human osteoblasts, fibroblasts, and macrophages
Authors: Dalal Ali , Pawar Vivek , McAllister Kyron , Weaver Carolyn , Hallab Nadim J.
Published: May 2012

The performance of total joint arthroplasty (TJA) depends on the size/shape, material, and amounts of implant debris. Much remains unknown in terms of which types of debris are most reactive. We compared the responses of human periimplant cells, osteoblasts, fibroblasts, and macrophages, exposed to particles of different metal‐based particles (i.e., cobalt‐chromium‐molybdenum (CoCrMo) alloy, titanium (Ti) alloy, zirconium (Zr) oxide, and Zr alloy. CoCrMo‐alloy particles were by far the most toxic (p< 0.05) and decreased viability and proliferation of human osteoblasts, fibroblasts, and macrophages by >50% at a dose of only 50 particles per cell. All particle types induced the production of interleukin (IL)‐6, tumor necrosis factor (TNF)‐α, and IL‐8 by osteoblasts, fibroblasts, and monocytes/macrophages. However, the greatest cytokine responses of macrophages were to CoCrMo alloy (TNF‐α and IL‐8) and Ti alloy (IL‐1β). Likewise, the greatest responses of fibroblasts and osteoblasts were to CoCrMo alloy (IL‐6 and TNF‐α) (i.e., IL‐6 300 pg/mL; 30‐fold max, TNF‐α 150 pg/mL; 15‐fold max) versus controls. For macrophages, CoCrMo particles induced IL‐8 (> 2000 pg/mL; approx 100‐fold max) above controls and were also significantly elevated above levels produced by Zr‐based particles. Submicron sized (0.2‐0.9 μm) Zr‐based particles (originally presumed to be more reactive) induced less toxicity and inflammatory responses when compared with larger (approx 1 μm) CoCrMo‐alloy and Ti‐alloy particles. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2012.
Augmenting the articular cartilage‐implant interface: Functionalizing with a collagen adhesion protein
Authors: Allon Aliza A. , Ng Kenneth W. , Hammoud Sommer , Russell Brooke H. , Jones Casey M. , Rivera Jose J. , Schwartz Jeffrey , Hook Magnus , Maher Suzzane A.
Published: May 2012

The lack of integration between implants and articular cartilage is an unsolved problem that negatively impacts the development of treatments for focal cartilage defects. Many approaches attempt to increase the number of matrix‐producing cells that can migrate to the interface, which may help to reinforce the boundary over time but does not address the problems associated with an initially unstable interface. The objective of this study was to develop a bioadhesive implant to create an immediate bond with the extracellular matrix components of articular cartilage. We hypothesized that implant‐bound collagen adhesion protein (CNA) would increase the interfacial strength between a poly(vinly alcohol) implant and an articular cartilage immediately after implantation, without preventing cell migration into the implant. By way of a series of in vitro immunohistochemical and mechanical experiments, we demonstrated that (i) free CNA can bind to articular cartilage, (ii) implant‐bound CNA can bind to collagen type II and (iii) implants functionalized with CNA result in a fourfold increase in interfacial strength with cartilage relative to untreated implants at day zero. Of note, the interfacial strength significantly decreased after 21 days in culture, which may be an indication that the protein itself has lost its effectiveness. Our data suggest that functionalizing scaffolds with CNA may be a viable approach toward creating an initially stable interface between scaffolds and articular cartilage. Further efforts are required to ensure long‐term interface stability. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2012.
Compositional dependence of hematopoietic stem cells expansion on bioceramic composite scaffolds for bone tissue engineering
Authors: Mishra Sarika , Rajyalakshmi A. , Balasubramanian K.
Published: May 2012

Bioceramics are although well known for their osteoinductive and osseointegrative properties in bone tissue regeneration, yet, they are inappropriate for load bearing applications due to inadequate mechanical strength. In this article, the authors report the expansion of hematopoietic stem cells (HSCs) on as‐synthesized composite scaffolds from hydroxyapatite and β‐tricalcium phosphate for bone tissue engineering, in an adequate load‐bearing application. The physical, structural, and mechanical properties of the composite scaffolds have been examined and correlated with the in vitro adhesion pattern of HSCs. The results indicated that the response of HSCs varies with change in the stoichiometry of composite scaffolds. The H2T2 scaffolds have exhibited the highest expansion of CD34+ cells and long‐term culture initiating cells when compared with other stoichiometries. The results suggest that H2T2 composite can be a potential strategic bone‐graft substitute in contrast with monolithic bioceramics, serving a dual role of bioresorbability and enhanced load‐bearing capacity. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 100A: 2483–2491, 2012.
Tissue engineering of ureteral grafts by seeding urothelial differentiated hADSCs onto biodegradable ureteral scaffolds
Authors: Shi Jian‐Guo , Fu Wei‐Jun , Wang Xiao‐Xiong , Xu Yong‐De , Li Gang , Hong Bao‐Fa , Wang Yan , Du Zhi‐Yan , Zhang Xu
Published: May 2012

The study is aimed to evaluate the differentiation potential of human adipose‐derived stem cells (hADSCs) into urothelial lineage, and to assess possibility of constructing ureteral grafts using the differentiated hADSCs and a novel polylactic acid (PLA)/collagen scaffolds. HADSCs were indirectly cocultured with urothelial cells in a transwell coculture system for urothelial differentiation. After 14 days coculturing, differentiation was evaluated by detecting urothelial lineage markers (cytokeratin‐18 and uroplakin 2) in mRNA and protein level. Then the differentiated hADSCs were seeded onto PLA/collagen ureteral scaffolds and culturedin vitrofor 1 week. The biocompatibility of the scaffolds was tested by scanning electron microscopy (SEM) and MTT analysis. At last, the cell/scafflod grafts were subcutaneously implanted into 4‐week‐old female athymic mice for 14 days. The results demonstrated that the hADSCs could be efficiently induced into urothelial lineage by indirect coculture. The differentiated cells seeded onto the PLA/collagen ureteral scaffolds survived up to 7 days and maintained proliferationin vitro, which indicated that the scaffolds displayed good biocompatibility.In vivostudy showed that the differentiated cells in the grafts survived, formed multiple layers on the scaffolds and expressed urothelial lineage markers. In conclusion, hADSCs may serve as an alternative cell resource in cell‐based tissue engineering for ureteral reconstruction. These cells could be employed to construct a model of ureteral engineering grafts and be effectively appliedin vivo, which could be a new strategy on ureteral replacement with applicable potential in clinical research. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 100A:2612–2622, 2012.