bluuebunny/crossref_metadata_2025 huggingface dataset:
Tolerance to Dietary Phenolics and Diet Breadth in Three Seed‐eating Birds: Implications for Graminivory
Authors: RÍOS JUAN MANUEL , MANGIONE ANTONIO MARCELO , MARONE LUIS
Published: June 2012

The ability to cope with plant secondary compounds (PSCs) has profound implications for an animal's behavior. In the present study, we assessed the tolerance to dietary phenolics in three seed‐eating birds: Zonotrichia capensis, Saltatricula multicolor, and Diuca diuca, which differ in their diet breadth. Seeds in their habitat have distinct chemical composition: grass seeds have less PSCs, specifically, less total phenolics than forb seeds. Based on the detoxification limitation hypothesis and using published data of the natural history of these birds in the central Monte desert, we postulate that predominantly and exclusively graminivorous birds such as D. diuca and S. multicolor, respectively, are less tolerant due, in part, to a lower detoxification capacity than those with greater diet breadth, Z. capensis. To achieve this goal, we measured the food intake of diets varying in their concentration of tannic acid (TA). Indicators of tolerance were body mass change, food, TA and water intake, and glucuronic acid output throughout the experiment. Zonotrichia capensis performed better along the tolerance experiment: it maintained body mass from 0 to 4% TA diet, food and TA intake were higher than the other two species at the end of the experiment, and glucuronic acid output by Z. capensis was greater than D. diuca and S. multicolor from 2% TA diet until the end of the experiment. Our results suggest that Z. capensis is the most tolerant species and this physiological trait may explain their greater diet breadth. J. Exp. Zool. 00A:1‐9, 2012. © 2012 Wiley Periodicals, Inc.
Climatic variations in Central America and the Caribbean
Authors: Hastenrath Stefan , Polzin Dierk
Published: June 2012

Resuming earlier work, this study explores the circulation mechanisms of rainfall variations in Central America and the Caribbean during 1921–1986. Regarding interannual variability, correlation analysis shows as favourable for abundant rainfall in the region warm surface waters, low pressure, upward motion, and weak tradewinds on the Atlantic side and over the eastern Pacific enhanced southerlies and a northward displaced intertropical convergence zone. In the course of the twentieth century, the region experienced alternations between protracted and contrastingly extreme regimes of rainfall, from wet 1931–1938 to dry 1939–1947 to wet 1950–1956 to dry 1971–1978. Changes in circulation patterns from the dry to the wet regimes are in the sense of correlations in interannual variability, pattern changes being broadly inverse in the evolution from the wet to the dry regimes. The alternations between contrasting circulation and rainfall regimes are reflected in changing lake levels. The study exemplifies the information value of a novel circulation data set. Copyright © 2012 Royal Meteorological Society
Greenhouse warming and solar brightening in and around the Alps
Authors: Philipona Rolf
Published: June 2012

At low elevations (500 m a.s.l.) Central Europe's surface temperature increased about 1.3 °C since 1981. Interestingly, at high elevations (2200 m a.s.l.) in the Alps, temperature rose less than 1 °C over the same period. Detailed investigations of temperature, humidity and the radiation budget at lowland and alpine climate stations now show that the difference in temperature rise is likely related to unequal solar‐ and greenhouse warming. The analysis shows that the important decline of anthropogenic aerosols in Europe since the mid‐1980s led to solar brightening at low elevations, whereas inherent low aerosol concentrations at high elevations led to only minor changes of solar radiation in the Alps. In the Lowland, absolute humidity and also total net radiation show an about 6% K−1 Clausius–Clapeyron conform increase with temperature since the 1980s. In the Alps, however, the percentage increase rate of humidity and total net radiation is more than twice as large. This large water vapour increase in the Alps is likely related to strong warming and thermal advection in the Lowlands, and may also have increased due to atmospheric circulation changes. Hence, while in the Alps temperature increased primarily due to strong water vapour enhanced greenhouse warming, solar brightening combined with anthropogenic greenhouse gas and water vapour feedback greenhouse warming led to a higher temperature increase at low elevations in Central Europe. Copyright © 2012 Royal Meteorological Society
Solar global ultraviolet and broadband global radiant fluxes and their relationships with aerosol optical depth at New Delhi
Authors: Bano Tarannum , Singh Sachchidanand , Gupta N. C. , John Thomas
Published: June 2012

The solar global ultraviolet (GUV) and broadband global (G) radiation flux obtained on a horizontal plane in Delhi, during April 2010 to March 2011 have been used to investigate the temporal variability of these radiations and their ratio, fraction of UV (FUV). For the first time the clearness index (KT) has been estimated over Delhi and its variability during different months of the year and season has been studied in detail. The impact of atmospheric aerosols on KT has also been studied. It has been found that for every unit increase in aerosol optical depth (AOD) at 340 nm, KT decreases by 0.06. A strong anti‐correlation with correlation coefficient − 0.75 is observed between AOD and KT. On the basis of our field experience and observations at Delhi it is found that for highly cloudy and overcast conditions 0⩽KT⩽0.15, for partial cloudy or hazy conditions 0.15⩽KT⩽0.21 and KT > 0.21 for clear sky conditions. In addition, during foggy days in winter we have found KT values lying in the range 0.12–0.18 at Delhi. The day‐time daily‐averaged fluxes GUV and G varied in the range 0.15–1.23 MJ m−2 and 3.36–27.02 MJ m−2, respectively. The GUV and G showed similar pattern during the year except for the wet season when the FUV increased possibly due to an increase in water vapour concentration. Copyright © 2012 Royal Meteorological Society
Relative contributions of design, alignment, and loading variability in knee replacement mechanics
Authors: Fitzpatrick Clare K. , Clary Chadd W. , Laz Peter J. , Rullkoetter Paul J.
Published: June 2012

Substantial variation in total knee replacement (TKR) outcomes exists within the patient population. Some of this variability is due to differences in the design of the implanted components and variation in surgical alignment, while other variability is due to differences in the applied forces and torques due to anatomic and physiological differences within a patient population. We evaluated the relative contributions of implant design, surgical alignment, and patient‐specific loading variability to overall tibiofemoral joint mechanics to provide insight into which measures can be influenced through design and surgical decisions, and which are inherently dependent on variation within the patient population and should be considered in the robustness of the implant design and surgical procedure. Design, surgical, and loading parameters were assessed using probabilistic finite element methods during simulated stance‐phase gait and squat activities. Patient‐specific loading was found to be the primary contributor to joint loading and kinematics during low flexion, particularly under conditions of high external loads (for instance, the gait cycle with high internal–external torque), while design and surgical factors, particularly femoral posterior radius and posterior slope of the tibial insert became increasingly important in TKR performance in deeper flexion. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:2015–2024, 2012
In vitro and in vivo antifungal activity of a water‐dilutable cassia oil microemulsion against Geotrichum citri‐aurantii
Authors: Xu Shi‐Xiang , Li Yi‐Chen , Liu Xia , Mao Li‐Juan , Zhang Hui , Zheng Xiao‐Dong
Published: June 2012

BACKGROUND: Recently, food‐grade microemulsions have been of increasing interest to researchers and have shown great potential in industrial applications. In this study a food‐grade water‐dilutable microemulsion system with cassia oil as oil, ethanol as cosurfactant, Tween 20 as surfactant and water was developed and its antifungal activity in vitro and in vivo against Geotrichum citri‐aurantii was assessed.

RESULTS: The phase diagram results confirmed the feasibility of forming a water‐dilutable microemulsion based on cassia oil. One microemulsion formulation, cassia oil/ethanol/Tween 20 = 1:3:6 (w/w/w), was selected with the capability to undergo full dilution with water. The average particle size was 6.3 nm. The in vitro antifungal experiments showed that the microemulsion inhibited fungal growth on solid medium and prevented arthroconidium germination in liquid medium and that cassia oil had stronger activity when encapsulated in the microemulsion. The in vivo antifungal experiments indicated that the water‐dilutable microemulsion was effective in preventing postharvest diseases of citrus fruits caused by G. citri‐aurantii.

CONCLUSION: The results of this study suggest a promising utilisation of water‐dilutable microemulsions based on essential oils for the control of postharvest diseases. Copyright © 2012 Society of Chemical Industry
Wine composition plays an important role in the control of carcinogenic precursor formation by Lactobacillus hilgardii X1B
Authors: Arena Mario E , Lisi María S , Manca de Nadra María C , Alberto María R
Published: June 2012

BACKGROUND: Lactobacillus hilgardii, a wine lactic acid bacterium, is able to use arginine, through the arginine deiminase pathway with the formation of citrulline, a precursor of the carcinogen ethyl carbamate. The influence of different Argentine wine varieties (Merlot, Cabernet Sauvignon and Malbec), on bacterial growth and arginine metabolism was examined. Furthermore, the effect of different components normally present in wines on the enzyme activities of the arginine deiminase system was determined.

RESULTS: Malbec wine under all conditions assayed (33, 50 and 100% supplemented wine:basal media) showed higher arginine consumption and citrulline production than the other wines, as well as the highest bacterial growth and survival of Lactobacillus hilgardii X1B. Glucose and L‐malic inhibited both arginine deiminase enzymes while fructose and citric acid only inhibited arginine deiminase. The red wines assayed in this study had different composition, and this is an explanation for the different behavior of the bacterium.

CONCLUSION: The highest citrulline production in Malbec wine could be correlated with its lower concentrations of glucose, fructose, citric and phenolic acid than the other wines. Therefore, a wine with lower concentration of these sugars and acids could be dangerous due to the formation of ethyl carbamate precursors. Copyright © 2012 Society of Chemical Industry
Tourism Experience Network: Co‐creation of Experiences in Interactive Processes
Authors: Sfandla Chouki , Björk Peter
Published: June 2012

This article launches a new framework, the Tourism Experience Network (TEN), which explores co‐creation of experiences. The TEN framework absorbs value as experience logic in tourism marketing. Its uniqueness illustrates structuring processes and includes consumers/tourists in the service management. A theoretical explorative technique based on literature was used to construct the TEN. It departures from interactive networks, new service paradigm and tourism marketing, and contributes to tourism experience theories. Inspiration from the Industrial Marketing and Purchasing (IMP) group was embraced to modify issues inherent from traditional networks—the ARA model. By linking this approach with experience, actors are defined as experience facilitators in tourism and networks. Copyright © 2012 John Wiley & Sons, Ltd.
Spectrophotometric analysis of chlorophyll pigments in canola and rapeseed oils
Authors: Daun James K.
Published: June 2012

Of all the vegetable oils commonly in production, rapeseed and canola oil have the highest level of undesirable chlorophyll pigments. Chlorophyll is desirable as a flavour and colour agent in olive oil, the other species with significant levels. In canola and rapeseed oils, chlorophyll is not desired because it imparts an undesirable colour, especially in North America where consumers are accustomed to colourless oils. It also makes the processed oils more susceptible to oxidation, even after the chlorophyll components have been removed. The content and role of chlorophyll in canola seed and oil have been well reviewed recently [1].
Finite lattices and Gröbner bases
Authors: Herzog Jürgen , Hibi Takayuki
Published: June 2012

Gröbner bases of binomial ideals arising from finite lattices will be studied. In terms of Gröbner bases and initial ideals, a characterization of finite distributive lattices as well as planar distributive lattices will be given.
A class of delayed viral models with saturation infection rate and immune response
Authors: Wang Xia , Liu Shengqiang
Published: June 2012

In this paper, a class of three delayed viral dynamics models with immune response and saturation infection rate are proposed and studied. By constructing suitable Lyapunov functionals, we derive the basic reproduction numberR0and the corresponding immune response reproduction numbers for the viral infection models, and establish that the global dynamics are completely determined by the values of the related basic reproduction number and immune response reproduction numbers. Copyright © 2012 John Wiley & Sons, Ltd.
Flux intensity functions for the Laplacian at axisymmetric edges
Authors: Nkemzi Boniface , Jung Michael
Published: June 2012

We derive explicit representation formulas for the computation of flux intensity functions for mixed boundary value problems for the Poisson equation in axisymmetric domains with edges. We rely on the decomposition of the boundary value problems in three dimensions by means of partial Fourier analysis with respect to the rotational angle into boundary value problems in the two‐dimensional meridian domain of . Utilizing smooth cutoff functions, the solutions of the reduced problems are analyzed semi‐analytically near corners of the plane meridian domain, and the edge flux intensity functions are constructed via Fourier synthesis and convergence analysis. The formulas are also applicable in the case of crack fronts. The constructive nature of the formulas provides in a straightforward way an efficient strategy for the accurate computation of edge flux intensity functions in axisymmetric domains. A demonstration example that illustrates the application of the formulas is presented. Copyright © 2012 John Wiley & Sons, Ltd.
Regularized Dirac delta functions for phase field models
Authors: Lee Hyun Geun , Kim Junseok
Published: June 2012

The phase field model is a highly successful computational technique for capturing the evolution and topological change of complex interfaces. The main computational advantage of phase field models is that an explicit tracking of the interface is unnecessary. The regularized Dirac delta function is an important ingredient in many interfacial problems that phase field models have been applied. The delta function can be used to postprocess the phase field solution and represent the surface tension force. In this paper, we present and compare various types of delta functions for phase field models. In particular, we analytically show which type of delta function works relatively well regardless of whether an interfacial phase transition is compressed or stretched. Numerical experiments are presented to show the performance of each delta function. Numerical results indicate that (1) all of the considered delta functions have good performances when the phase field is locally equilibrated; and (2) a delta function, which is the absolute value of the gradient of the phase field, is the best in most of the numerical experiments. Copyright © 2012 John Wiley & Sons, Ltd.
A hybridized discontinuous Petrov–Galerkin scheme for scalar conservation laws
Authors: Moro D. , Nguyen N. C. , Peraire J.
Published: June 2012

We present a hybridized discontinuous Petrov–Galerkin (HDPG) method for the numerical solution of steady and time‐dependent scalar conservation laws. The method combines a hybridization technique with a local Petrov–Galerkin approach in which the test functions are computed to maximize the inf‐sup condition. Since the Petrov–Galerkin approach does not guarantee a conservative solution, we propose to enforce this explicitly by introducing a constraint into the local Petrov–Galerkin problem. When the resulting nonlinear system is solved using the Newton–Raphson procedure, the solution inside each element can be locally condensed to yield a global linear system involving only the degrees of freedom of the numerical trace. This results in a significant reduction in memory storage and computation time for the solution of the matrix system, albeit at the cost of solving the local Petrov–Galerkin problems. However, these local problems are independent of each other and thus perfectly scalable. We present several numerical examples to assess the performance of the proposed method. The results show that the HDPG method outperforms the hybridizable discontinuous Galerkin method for problems involving discontinuities. Moreover, for the test case proposed by Peterson, the HDPG method provides optimal convergence of order k + 1. Copyright © 2012 John Wiley & Sons, Ltd.
Floating stress‐point integration meshfree method for large deformation analysis of elastic and elastoplastic materials
Authors: Onishi Y. , Amaya K.
Published: June 2012

A new meshfree formulation of stress‐point integration, called the floating stress‐point integration meshfree method, is proposed for the large deformation analysis of elastic and elastoplastic materials. This method is a Galerkin meshfree method with an updated Lagrangian procedure and a quasi‐implicit time‐advancing scheme without any background cell for domain integration. Its new formulation is based on incremental equilibrium equations derived from the incremental virtual work equation, which is not generally used in meshfree formulations. Hence, this technique allows the temporal continuity of the mechanical equilibrium to be naturally achieved. The details of the new formulation and several examples of the large deformation analysis of elastic and elastoplastic materials are presented to show the validity and accuracy of the proposed method in comparison with those of the finite element method. Copyright © 2012 John Wiley & Sons, Ltd.
Dynamic failure simulation of quasi‐brittle material in dual particle dynamics
Authors: Sanchez J.J. , Randles P.W.
Published: June 2012

The feasibility of simulating dynamic fracture in quasi‐brittle material using a dual particle computational method with a smeared‐crack representation of material failure is explored. The computational approach utilized is dual particle dynamics, which incorporates a moving least squares interpolation of field variables between two sets of particles that discretize the spatial domain, and a Lagrangian description of the moving least squares weight function. Material failure is represented by an inelastic continuum strain contribution obtained from smearing the effect of a cohesive failure model over a discrete volume of material. A three‐dimensional simulation of the initiation and development of a dynamic mode I failure is performed for the case of approximate plane wave propagation. Post failure wave interaction with the resulting global failure surface replicates the behavior of a stress‐free boundary condition. The computational material failure approach is applied to problems of spalling in split Hopkinson pressure bar tests. Experimental failure trends are reproduced successfully.Copyright © 2012 John Wiley & Sons, Ltd.
Partitioned vibration analysis of internal fluid‐structure interaction problems
Authors: González José A. , Park K.C. , Lee I. , Felippa C.A. , Ohayon R.
Published: June 2012

A partitioned, continuum‐based, internal fluid–structure interaction (FSI) formulation is developed for modeling combined sloshing, acoustic waves, and the presence of an initial pressurized state. The present formulation and its computer implementation use the method of localized Lagrange multipliers to treat both matching and non‐matching interfaces. It is shown that, with the context of continuum Lagrangian kinematics, the fluid sloshing and acoustic stiffness terms originate from an initial pressure term akin to that responsible for geometric stiffness effects in solid mechanics. The present formulation is applicable to both linearized vibration analysis and nonlinear FSI transient analysis provided that a convected kinematics is adopted for updating the mesh geometry in a finite element discretization. Numerical examples illustrate the capability of the present procedure for solving coupled vibration and nonlinear sloshing problems. Copyright © 2012 John Wiley & Sons, Ltd.
Embedded kinematic boundary conditions for thin plate bending by Nitsche's approach
Authors: Harari Isaac , Shavelzon Evgeny
Published: June 2012

A stabilized variational formulation, based on Nitsche's method for enforcing boundary constraints, leads to an efficient procedure for embedding kinematic boundary conditions in thin plate bending. The absence of kinematic admissibility constraints allows the use of non‐conforming meshes with non‐interpolatory approximations, thereby providing added flexibility in addressing the C1‐continuity requirements typical of these problems. Work‐conjugate pairs weakly enforce kinematic boundary conditions. The pointwise enforcement of corner deflections is key to good performance in the presence of corners. Stabilization parameters are determined from local generalized eigenvalue problems, guaranteeing coercivity of the discrete bilinear form. The accuracy of the approach is verified by representative computations with bicubic C2 B‐splines, exhibiting optimal rates of convergence and robust performance with respect to values of the stabilization parameters. Copyright © 2012 John Wiley & Sons, Ltd.
A sub‐grid scale finite element agglomeration multigrid method with application to the Boltzmann transport equation
Authors: Buchan A.G. , Pain C.C. , Umpleby A.P. , Smedley‐Stevenson R.P.
Published: June 2012

This article describes a new element agglomeration multigrid method for solving partial differential equations discretised through a sub‐grid scale finite element formulation. The sub‐grid scale discretisation resolves solution variables through their separate coarse and fine scales, and these are mapped between the multigrid levels using a dual set of transfer operators. The sub‐grid scale multigrid method forms coarse linear systems, possessing the same sub‐grid scale structure as the original discretisation, that can be resolved without them being stored in memory. This is necessary for the application of this article in resolving the Boltzmann transport equation as the linear systems become extremely large. The novelty of this article is therefore a matrix‐free multigrid scheme that is integrated within its own sub‐grid scale discretisation using dual transfer operators and applied to the Boltzmann transport equation.

The numerical examples presented are designed to show the method's preconditioning capabilities for a Krylov space‐based solver. The problems range in difficulty, geometry and discretisation type, and comparisons made with established methods show this new approach to perform consistently well. Smoothing operators are also analysed and this includes using the generalized minimal residual method. Here, it is shown that an adaptation to the preconditioned Krylov space is necessary for it to work efficiently. Copyright © 2012 John Wiley & Sons, Ltd.
H1‐Galerkin expanded mixed finite element methods for nonlinear pseudo‐parabolic integro‐differential equations
Authors: Che Haitao , Zhou Zhaojie , Jiang Ziwen , Wang Yiju
Published: June 2012

H1‐Galerkin mixed finite element method combined with expanded mixed element method is discussed for nonlinear pseudo‐parabolic integro‐differential equations. We conduct theoretical analysis to study the existence and uniqueness of numerical solutions to the discrete scheme. A priori error estimates are derived for the unknown function, gradient function, and flux. Numerical example is presented to illustrate the effectiveness of the proposed scheme. © 2012 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2013
Posterior brain in fetuses with trisomy 18, trisomy 13 and triploidy at 11 to 13 weeks' gestation
Authors: Ferreira Ana Fatima A. , Syngelaki Argyro , Smolin Anna , Vayna Ana‐Maria , Nicolaides Kypros H.
Published: June 2012

Objective

To measure changes in the posterior fossa of first‐trimester fetuses with trisomy 18, trisomy 13 and triploidy.

Methods

Brain stem (BS) diameter and BS to occipital bone (BSOB) diameter were measured in images of the midsagittal view of the face at 11+0 to 13+6 weeks from 45 trisomy 18, 21 trisomy 13 and 15 triploid fetuses and compared with values in 162 euploid fetuses.

Results

In euploid fetuses BS and BSOB diameters increased significantly with crown–rum length and the BS to BSOB ratio decreased. In all three aneuploidies BSOB diameter was significantly higher than in euploid fetuses. In trisomy 18 and trisomy 13, the BS diameter and BS to BSOB ratio were decreased. The BS to BSOB ratio was below the 5th percentile in 16 (35.6%), 17 (81.0%) and 5 (33.3%) of trisomy 18, trisomy 13 and triploidy, respectively. In 7 (8.6%) of the aneuploid fetuses there was open spina bifida and in all these cases the BS to BSOB ratio was above the 95th percentile.

Conclusions

At 11 to 13 weeks' gestation many fetuses with trisomy 18, trisomy 13 and triploidy have measurable abnormalities in the posterior brain. © 2012 John Wiley & Sons, Ltd.
Service users and care providers' experiences of tertiary combined fetal medicine clinics
Authors: Miller Sarah , Liao Lih‐Mei , Warner Deborah , Chitty Lyn S.
Published: June 2012

Objective

To explore service users and care providers' experiences of combined fetal medicine and specialist paediatric clinics.

Method

A brief survey of service users and care providers at combined fetal medicine clinics, which bring together multiple specialists and expertise for the management of pregnancies complicated by fetal cardiac, renal, neurological or surgical abnormalities.

Results

Two hundred and sixty‐one patients and 22 health professionals participated. More than 85% of women rated the clinic highly, 61% reported that the service had changed how they viewed the abnormality, and 53% reported that they would welcome further visits to the combined clinic. The majority of health professionals reported that combined clinics improved the accuracy of parental counselling and enhanced communication between specialties involved in the management of complicated pregnancies. The clinics are generally regarded as being useful for the training of junior staff.

Conclusion

A service model that combines fetal medicine and paediatric specialists in a single clinic can efficiently modify parental perspective on fetal anomalies and enhance professional communication and training. Condition‐specific information leaflets could further enhance service quality. A larger study involving a socio‐demographically stratified sample of service users is needed to provide more authoritative data. © 2012 John Wiley & Sons, Ltd.
Implications for CdTe and CIGS technologies production costs of indium and tellurium scarcity
Authors: Candelise Chiara , Winskel Mark , Gross Robert
Published: June 2012

Scarcity of indium and tellurium has been highlighted as a potential barrier for cadmium telluride (CdTe) and copper indium gallium (di)selenide (CIGS) thin film technologies to achieve both large‐scale deployment and reduction in production costs. With the aim of assessing the relative weight of the aforementioned concerns, this paper looks at indium and tellurium availability and implications for CIGS and CdTe production costs of their price increases. A breakdown of CdTe and CIGS module production costs is provided, accounting for the relative share of each component materials over total module cost. Conditions affecting usage of the key materials in CdTe and CIGS technologies are weighted against potential future indium and tellurium price escalation to provide a fuller picture of production cost implications for the thin film photovoltaics technologies. This includes exploring and quantifying the potential for innovation and technological developments (including efficiency increases, reduced absorber layer, higher material utilisation during deposition process) to ease the impact of possible future indium and tellurium supply constraints and price increases. Copyright © 2012 John Wiley & Sons, Ltd.
Comparative theoretical investigation of the formation of DNA interstrand crosslinks induced by two kinds of N‐nitroso compounds: nitrosoureas and nitrosamines
Authors: Zhao Lijiao , Ma Xinyan , Zhong Rugang
Published: June 2012

Nitrosamines and nitrosoureas are two families of N‐nitroso compounds (NNCs) with a common nitroso group connected to the nitrogen atom; however, the two types of analogs often exhibit distinct bioactivities when they have similar substructures in the side chains. Nitrosamines are usually considered to be potent carcinogens to various organs and species, whereas nitrosoureas can inhibit cancer cell growth. This distinction between the two types of compounds complicates our understanding of the structure–bioactivity relationship of NNCs. In this work, the mechanisms for the formation of DNA interstrand crosslinks induced by nitrosoureas and nitrosamines, which are an important DNA damage related to the cytotoxicity of NNCs, were compared using the density functional theory method. 1,3‐Bis‐(2‐chloroethyl)‐1‐nitrosourea (BCNU) and the bifunctional metabolite of diethylnitrosamine, N‐nitrosoethyl‐(2‐hydroxyethyl)amine sulfonate (NEHEAS), were used as the computational models. Four pathways for the formation of G–C crosslinks induced by BCNU and NEHEAS were compared. The results show that the crosslinking mechanisms initiated by α‐alkylation are energetically feasible for both BCNU and NEHEAS, and the decompositions of BCNU and NEHEAS represent the rate‐limiting steps. However, for the crosslinking mechanisms initiated by β‐alkylation, BCNU and NEHEAS exhibit different preferences. The energy barrier for the decomposition of the BCNU‐induced β‐alkylation product is much higher than that of NEHEAS. Such an energy barrier may inhibit the mechanism of BCNU initiated by β‐alkylation. Consequently, it is postulated that BCNU and NEHEAS induce DNA interstrand crosslinks via different mechanisms, which may distinguish the bioactivity of the two types of NNCs. Copyright © 2012 John Wiley & Sons, Ltd.
Reactions of substituted aspirins with amino acids
Authors: Orth Elisa S. , Medeiros Michelle , Souza Bruno S. , Caon Natália B. , Kirby Anthony J. , Nome Faruk
Published: June 2012

Acyl transfers are key reactions in biology and in the laboratory. In biological systems they are involved in energy transport, in the assembly of complex molecules and in the mechanisms of efficient action of many hydrolytic enzymes. We report a mechanistic and calculational study of the selective N‐acylation reactions of amino acids by substituted aspirins, under mild conditions, in water at 25 °C. The acetylated amino‐acid products of the reactions were identified by nuclear magnetic resonance, and the reaction steps were studied by density functional theory. Copyright © 2012 John Wiley & Sons, Ltd.
Photoresponsive receptors for binding and releasing anions
Authors: Lee Semin , Flood Amar H.
Published: June 2012

Photoresponsive receptors allow users to modulate when and where molecular hosts can bind and release their targets. This capability was pioneered in biochemistry, trained on cations, and is only now emerging in the recognition chemistry of anions. This mini review outlines the five instances where anion receptors have been manipulated by light. Cylindrical, acyclic, and helical receptors have been integrated with azobenzenes, stiff‐stilbenes, and dithienylethenes to generate modest‐to‐moderate changes in the binding affinities for various halides and polyatomic anions. The central design requirement involves choosing the appropriate photoswitch such that the two photostates can define two different organizations of the receptor, thus, enabling one state to bind better than the other. This challenge underscores the importance of analyzing the possible conformations, complexes, and stoichiometries that may be accessible by host and guest as a means to identify structures that will successfully elicit a switching response. Copyright © 2012 John Wiley & Sons, Ltd.
A new access to polypyrrole‐based functionalized magnetic core‐shell nanoparticles
Authors: Karsten Sebastian , Nan Alexandrina , Turcu Rodica , Liebscher Jürgen
Published: June 2012

Magnetic nanoparticles (NP) have found various important applications in nanotechnology and nanomedicine, because they can be manipulated by external magnetic field and can be functionalized on their surface. Although a variety of magnetic core shell NP are known present research focuses on new NP with better properties (reduced toxicity, high colloidal and chemical stability, wide scope of application) and more straightforward and reproducible syntheses. In this work, we report the synthesis of azido‐functionalized polypyrrole (PPy)‐based superparamagnetic core shell NP by surface initiated polymerization wherein miniemulsion technique have been applied in this field for the first time. The new NP are attractive for biomedical applications because the PPy is biocompatible, the shell can easily be functionalized by Cu‐catalyzed click‐reaction as shown by the introduction of biotin and the material exhibits superparamagnetic behavior. The surface initiated polymerization is carried out at new magnetite NP, which are stabilized by pyrrol‐containing fatty acids. Although these starting NP lack a polymer shell, they show a remarkable stability and thus have the potential for further functionalization. The magnetic NP are characterized by various methods such as FTIR, X‐ray photoelectron spectroscopy, magnetic measurements, thermal gravimetric analysis, and dynamic light scattering. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Benzooxadiazaole‐based D–A–D co‐oligomers: Synthesis and electropolymerization
Authors: Pati Palas Baran , Das Soumyajit , Zade Sanjio S.
Published: June 2012

Four D–A–D type co‐oligomers have been synthesized by Stille condensation between monostannyl derivatives of furan/thiophene/selenophene/3,4‐ethylenedioxythiophene (EDOT) and 4,7‐dibromo‐benzo[1,2,5]oxadiazole. All these co‐oligomers were successfully electrochemically polymerized in dichloromethane and characterized by spectroelectrochemistry. All four polymers possess narrow optical band gap. Spectroelectrochemical studies of polymer films on indium tin oxide revealed that the replacement of donor EDOT with furan/thiophene/selenophene has affected the low‐energy charge‐carrier (bipolaron) formation significantly. Kinetic studies based on chronoamperometry show that the polymer P5 (EDOT‐capped benzo[1,2,5]oxadiazole system) possess better electrochromic property with high transmittance (66%) in visible region than the other copolymers. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Negative cancer stereotypes and disease‐specific self‐concept in head and neck cancer
Authors: Wong Janice C. , Payne Ada Y. M. , Mah Kenneth , Lebel Sophie , Lee Ruth N. F. , Irish Jonathan , Rodin Gary , Devins Gerald M.
Published: June 2012

Background

Life‐threatening diseases, such as head and neck cancer (HNCa), can stimulate the emergence of a new disease‐specific self‐concept. We hypothesized that (i) negative cancer‐stereotypes invoke distancing, which inhibits the adoption of a disease‐specific self‐concept and (ii) patient characteristics, disease and treatment factors, and cancer‐related stressors moderate the phenomenon.

Methods

Head and neck cancer outpatients (N = 522) completed a semantic‐differential measure of disease‐specific self‐concept (perceived similarity to the ‘cancer patient’) and other self‐report measures in structured interviews. Negative cancer‐stereotypes were represented by the number of semantic‐differential dimensions (0–3) along which respondents evaluated the stereotypic ‘cancer patient’ negatively (i.e., negative valence). We tested the two‐way interactions between negative valence and hypothesized moderator variables.

Results

We observed significant negative valence × moderator interactions for the following: (i) patient characteristics (education, employment, social networks); (ii) disease and treatment factors (cancer‐symptom burden); and (iii) cancer‐related stressors (uncertainty, lack of information, and existential threats). Negative cancer stereotypes were consistently associated with distancing of self from the stereotypic ‘cancer patient,’ but the effect varied across moderator variables. All significant moderators (except employment and social networks) were associated with increasing perceived similarity to the ‘cancer patient’ when respondents maintained negative stereotypes; perceived similarity decreased when people were employed or had extensive social networks. Moderator effects were less pronounced when respondents did not endorse negative cancer stereotypes.

Discussion

When they hold negative stereotypes, people with HNCa distance themselves from a ‘cancer patient’ identity to preserve self‐esteem or social status, but exposure to cancer‐related stressors and adaptive demands may attenuate these effects. Copyright © 2012 John Wiley & Sons, Ltd.
Introduction of Basic Functionalities on the Surface of Granular Adsorbers by Low Pressure Plasma Processes
Authors: De Vietro Nicoletta , d'Agostino Riccardo , Fracassi Francesco
Published: June 2012

Low pressure plasma, generated in a radio frequency reactor under rotation, was utilized to modify the ability of granular substrates to adsorb volatile acid compounds. Carbon black granules were treated with NH3 or allylamine containing feeds, while sepiolite granules were processed only in allylamine fed discharges. The chemical modifications induced by plasma treatments were evaluated by means of X‐ray photoelectron spectroscopy studies and water contact angle measurements, while scanning electron microscope and Brunauer, Emmet, Teller analyses were performed to study the surface morphological changes caused by plasma processes. The ability of the treated materials to adsorb acids, in gas or vapour phase, was estimated with hydrochloric, acetic and propanoic acid, employing a home‐made test system. The results show that the optimized plasma treatments are able to improve the adsorption ability of carbon black and sepiolite granules for the three acids investigated.

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Electrospray ionization and matrix‐assisted laser desorption/ionization mass spectrometric analysis of extrapolysaccharides of Escherichia coli
Authors: Gedda Gangaraju , Gopal Judy , Wu Hui‐Fen
Published: June 2012

RATIONALE

Conventional studies of extracellular polymeric substances (EPS) typically require elaborate separation procedures or complicated sample pretreatment processes such as purification by dialysis and lyophilization. The objective of this study is to demonstrate the use of electrospray ionization (ESI) and matrix‐assisted laser desorption/ionization (MALDI) mass spectrometry (MS) as powerful techniques for direct analysis of EPS secreted by E. coli.

METHODS

We have compared the extraction efficiency of two widely used extraction methods including physical extraction (room‐temperature centrifugation and high‐speed centrifugation) and chemical extraction using EDTA and formaldehyde. We specify the most favorable extraction method and the analyte to extractant concentration with respect to mass spectrometric analysis of EPS, based on the results obtained from ESI‐MS and MALDI‐MS analysis.

RESULTS

Chemical extraction methods were found to be more efficient than physical extraction methods. Of the chemical extractants, EDTA was found more effective compared to formaldehyde and gave more EPS peaks during ESI‐ and MALDI‐MS analysis. We report the classification of E. coli EPS into loosely bound, bound and tightly bound EPS based on a simple modification of an existing methodology. Our studies showed that ESI‐MS was very effective for <300 Da EPS studies and MALDI‐MS more suitable for rapid analysis of EPS above mass range 400 Da.

CONCLUSIONS

This is a preliminary study reporting for the first time the feasibility of ESI‐MS and MALDI‐MS techniques for the analysis of bacterial EPS without prior complicated purification and separation methodologies. Copyright © 2012 John Wiley & Sons, Ltd.
Discrimination of stable isotopes in fin whale tissues and application to diet assessment in cetaceans
Authors: Borrell A. , Abad‐Oliva N. , Gómez‐Campos E. , Giménez J. , Aguilar A.
Published: June 2012

RATIONALE

In stable isotope research, the use of accurate, species‐specific diet‐tissue discrimination factors (i.e., Δ13C and Δ15N) is central to the estimation of trophic position relative to primary consumers and to the identification of the dietary sources of an individual. Previous research suggested that the diet of fin whales from the waters off northwestern Spain is overwhelmingly based on krill, thus permitting reliable calculation of discrimination values in this wild population.

METHODS

After confirming that the stable isotope ratios (δ13C and δ15N values) in muscle from 65 aged fin whales remained constant through age classes (4–65 years), the signatures were determined in muscle, bone protein, skin, liver, kidney, baleen plates and brain, as well as food (krill), from a subset of individuals to calculate discrimination factors. Signatures were determined by means of elemental analysis isotope ratio mass spectrometry (EA‐IRMS) using a ThermoFinnigan Flash 1112.

RESULTS

The isotopic values remained constant regardless of age. The mean Δ15N values between krill and whale tissues ranged from 2.04 in bone protein to 4.27‰ in brain, and those of Δ13C ranged from 1.28 in skin to 3.11‰ in bone protein. This variation was consistent with that found in other groups of mammals, and is attributed to variation in tissue composition and physiology.

CONCLUSIONS

Because discrimination factors are relatively constant between taxonomically close species, the results here obtained may be reliably extrapolated to other cetaceans to improve dietary reconstructions. The skin discrimination factors are of particular relevance to monitoring diet through biopsies or other non‐destructive sampling methods. The large difference in bone protein discrimination factors from those of other tissues should be taken into consideration when bone collagen is used to determine trophic level or to assess diet in paleodietary isotopic reconstructions. Copyright © 2012 John Wiley & Sons, Ltd.
Flocking under hierarchical leadership with a free‐will leader
Authors: Dong Jiu‐Gang
Published: June 2012

Recently, a model for flocking was introduced by Cucker and Smale together with a proof of convergence. This proof established unconditional convergence to flocking (i.e., to a common velocity), provided the interaction between agents was strong enough and conditional convergence otherwise. The strength of the interaction is measured by a parameter β, and the critical value at which unconditional convergence stops holding is β = 1 ∕ 2. This model was extended by Shen to allow for a hierarchical leadership structure among the agents, and similar convergence results were proved. But, for discrete time, convergence result was only for the flock with an overall leader moving with a constant velocity. In this note, we establish convergence result for the flock with a free‐will leader. Copyright © 2012 John Wiley & Sons, Ltd.
crimsonHex: a learning objects repository for programming exercises
Authors: Queirós Ricardo , Leal José Paulo
Published: June 2012

A repository of learning objects is a system that stores electronic resources in a technology‐mediated learning process. The need for this kind of repository is growing as more educators become eager to use digital educational contents and more of it becomes available. The sharing and use of these resources relies on the use of content and communication standards as a means to describe and exchange educational resources, commonly known as learning objects. This paper presents the design and implementation of a service‐oriented repository of learning objects called crimsonHex. This repository supports new definitions of learning objects for specialized domains and we illustrate this feature with the definition of programming exercises as learning objects and its validation by the repository. The repository is also fully compliant with existing communication standards and we propose extensions by adding new functions, formalizing message interchange and providing a REST interface. To validate the interoperability features of the repository, we developed a repository plug‐in for Moodle that is expected to be included in the next release of this popular learning management system. Copyright © 2012 John Wiley & Sons, Ltd.
Stable Long-Term Blood Formation by Stem Cells in Murine Steady-State Hematopoiesis
Authors: Zavidij Oksana , Ball Claudia R. , Herbst Friederike , Oppel Felix , Fessler Sylvia , Schmidt Manfred , von Kalle Christof , Glimm Hanno
Published: June 2012

Hematopoietic stem cells (HSCs) generate all mature blood cells during the whole lifespan of an individual. However, the clonal contribution of individual HSC and progenitor cells in steady-state hematopoiesis is poorly understood. To investigate the activity of HSCs under steady-state conditions, murine HSC and progenitor cells were genetically marked in vivo by integrating lentiviral vectors (LVs) encoding green fluorescent protein (GFP). Hematopoietic contribution of individual marked clones was monitored by determination of lentiviral integration sites using highly sensitive linear amplification-mediated-polymerase chain reaction. A remarkably stable small proportion of hematopoietic cells expressed GFP in LV-injected animals for up to 24 months, indicating stable marking of murine steady-state hematopoiesis. Analysis of the lentiviral integration sites revealed that multiple hematopoietic clones with both myeloid and lymphoid differentiation potential contributed to long-term hematopoiesis. In contrast to intrafemoral vector injection, intravenous administration of LV preferentially targeted short-lived progenitor cells. Myelosuppressive treatment of mice prior to LV-injection did not affect the marking efficiency. Our study represents the first continuous analysis of clonal behavior of genetically marked hematopoietic cells in an unmanipulated system, providing evidence that multiple clones are simultaneously active in murine steady-state hematopoiesis.