bluuebunny/crossref_metadata_2025 huggingface dataset:
Breaking beta: deconstructing the parasite transmission function
Authors: McCallum Hamish , Fenton Andy , Hudson Peter J. , Lee Brian , Levick Beth , Norman Rachel , Perkins Sarah E. , Viney Mark , Wilson Anthony J. , Lello Joanne
Published: March 2017

Transmission is a fundamental step in the life cycle of every parasite but it is also one of the most challenging processes to model and quantify. In most host–parasite models, the transmission process is encapsulated by a single parameter
β
. Many different biological processes and interactions, acting on both hosts and infectious organisms, are subsumed in this single term. There are, however, at least two undesirable consequences of this high level of abstraction. First, nonlinearities and heterogeneities that can be critical to the dynamic behaviour of infections are poorly represented; second, estimating the transmission coefficient
β
from field data is often very difficult. In this paper, we present a conceptual model, which breaks the transmission process into its component parts. This deconstruction enables us to identify circumstances that generate nonlinearities in transmission, with potential implications for emergent transmission behaviour at individual and population scales. Such behaviour cannot be explained by the traditional linear transmission frameworks. The deconstruction also provides a clearer link to the empirical estimation of key components of transmission and enables the construction of flexible models that produce a unified understanding of the spread of both micro- and macro-parasite infectious disease agents.

This article is part of the themed issue ‘Opening the black box: re-examining the ecology and evolution of parasite transmission’.
Transmission dynamics: critical questions and challenges
Authors: Antonovics Janis
Published: March 2017

This article overviews the dynamics of disease transmission in one-host–one-parasite systems. Transmission is the result of interacting host and pathogen processes, encapsulated with the environment in a ‘transmission triangle’. Multiple transmission modes and their epidemiological consequences are often not understood because the direct measurement of transmission is difficult. However, its different components can be analysed using nonlinear transmission functions, contact matrices and networks. A particular challenge is to develop such functions for spatially extended systems. This is illustrated for vector transmission where a ‘perception kernel’ approach is developed that incorporates vector behaviour in response to host spacing. A major challenge is understanding the relative merits of the large number of approaches to quantifying transmission. The evolution of transmission mode itself has been a rather neglected topic, but is important in the context of understanding disease emergence and genetic variation in pathogens. Disease impacts many biological processes such as community stability, the evolution of sex and speciation, yet the importance of different transmission modes in these processes is not understood. Broader approaches and ideas to disease transmission are important in the public health realm for combating newly emerging infections.

This article is part of the themed issue ‘Opening the black box: re-examining the ecology and evolution of parasite transmission’.
Host heterogeneity affects both parasite transmission to and fitness on subsequent hosts
Authors: Stephenson Jessica F. , Young Kyle A. , Fox Jordan , Jokela Jukka , Cable Joanne , Perkins Sarah E.
Published: March 2017

Infectious disease dynamics depend on the speed, number and fitness of parasites transmitting from infected hosts (‘donors’) to parasite-naive ‘recipients’. Donor heterogeneity likely affects these three parameters, and may arise from variation between donors in traits including: (i) infection load, (ii) resistance, (iii) stage of infection, and (iv) previous experience of transmission. We used the Trinidadian guppy,
Poecilia reticulata
, and a directly transmitted monogenean ectoparasite,
Gyrodactylus turnbulli
, to experimentally explore how these sources of donor heterogeneity affect the three transmission parameters. We exposed parasite-naive recipients to donors (infected with a single parasite strain) differing in their infection traits, and found that donor infection traits had diverse and sometimes interactive effects on transmission. First, although transmission speed increased with donor infection load, the relationship was nonlinear. Second, while the number of parasites transmitted generally increased with donor infection load, more resistant donors transmitted more parasites, as did those with previous transmission experience. Finally, parasites transmitting from experienced donors exhibited lower population growth rates on recipients than those from inexperienced donors. Stage of infection had little effect on transmission parameters. These results suggest that a more holistic consideration of within-host processes will improve our understanding of between-host transmission and hence disease dynamics.

This article is part of the themed issue ‘Opening the black box: re-examining the ecology and evolution of parasite transmission’.
Growth rate, transmission mode and virulence in human pathogens
Authors: Leggett Helen C. , Cornwallis Charlie K. , Buckling Angus , West Stuart A.
Published: March 2017

The harm that pathogens cause to hosts during infection, termed virulence, varies across species from negligible to a high likelihood of rapid death. Classic theory for the evolution of virulence is based on a trade-off between pathogen growth, transmission and host survival, which predicts that higher within-host growth causes increased transmission and higher virulence. However, using data from 61 human pathogens, we found the opposite correlation to the expected positive correlation between pathogen growth rate and virulence. We found that (i) slower growing pathogens are significantly more virulent than faster growing pathogens, (ii) inhaled pathogens and pathogens that infect via skin wounds are significantly more virulent than pathogens that are ingested, but (iii) there is no correlation between symptoms of infection that aid transmission (such as diarrhoea and coughing) and virulence. Overall, our results emphasize how virulence can be influenced by mechanistic life-history details, especially transmission mode, that determine how parasites infect and exploit their hosts.

This article is part of the themed issue ‘Opening the black box: re-examining the ecology and evolution of parasite transmission’.
Uncertain links in host–parasite networks: lessons for parasite transmission in a multi-host system
Authors: Walker Josephine G. , Plein Michaela , Morgan Eric R. , Vesk Peter A.
Published: March 2017

For many parasites, the full set of hosts that are susceptible to infection is not known, and this could lead to a bias in estimates of transmission. We used counts of individual adult parasites from historical parasitology studies in southern Africa to map a bipartite network of the nematode parasites of herbivore hosts that occur in Botswana. Bipartite networks are used in community ecology to represent interactions across trophic levels. We used a Bayesian hierarchical model to predict the full set of host–parasite interactions from existing data on parasitic gastrointestinal nematodes of wild and domestic ungulates given assumptions about the distribution of parasite counts within hosts, while accounting for the relative uncertainty of less sampled species. We used network metrics to assess the difference between the observed and predicted networks, and to explore the connections between hosts via their shared parasites using a host–host unipartite network projected from the bipartite network. The model predicts a large number of missing links and identifies red hartebeest, giraffe and steenbok as the hosts that have the most uncertainty in parasite diversity. Further, the unipartite network reveals clusters of herbivores that have a high degree of parasite sharing, and these clusters correspond closely with phylogenetic distance rather than with the wild/domestic boundary. These results provide a basis for predicting the risk of cross-species transmission of nematode parasites in areas where livestock and wildlife share grazing land.

This article is part of the themed issue ‘Opening the black box: re-examining the ecology and evolution of parasite transmission’.
Parasite transmission in a natural multihost–multiparasite community
Authors: Auld Stuart K. J. R. , Searle Catherine L. , Duffy Meghan A.
Published: March 2017

Understanding the transmission and dynamics of infectious diseases in natural communities requires understanding the extent to which the ecology, evolution and epidemiology of those diseases are shaped by alternative hosts. We performed laboratory experiments to test how parasite spillover affected traits associated with transmission in two co-occurring parasites: the bacterium
Pasteuria ramosa
and the fungus
Metschnikowia bicuspidata
. Both parasites were capable of transmission from the reservoir host (
Daphnia dentifera
) to the spillover host (
Ceriodaphnia dubia
), but this occurred at a much higher rate for the fungus than the bacterium. We quantified transmission potential by combining information on parasite transmission and growth rate, and used this to compare parasite fitness in the two host species. For both parasites, transmission potential was lower in the spillover host. For the bacterium, virulence was higher in the spillover host. Transmission back to the original host was high for both parasites, with spillover influencing transmission rate of the fungus but not the bacterium. Thus, while inferior, the spillover host is not a dead-end for either parasite. Overall, our results demonstrate that the presence of multiple hosts in a community can have important consequences for disease transmission, and host and parasite fitness.

This article is part of the themed issue ‘Opening the black box: re-examining the ecology and evolution of parasite transmission’.
Sinusoidal voltage protocols for rapid characterisation of ion channel kinetics
Authors: Beattie Kylie A. , Hill Adam P. , Bardenet Rémi , Cui Yi , Vandenberg Jamie I. , Gavaghan David J. , de Boer Teun P. , Mirams Gary R.
Published: March 2017

Understanding the roles of ion currents is crucial to predict the action of pharmaceuticals and mutations in different scenarios, and thereby to guide clinical interventions in the heart, brain and other electrophysiological systems. Our ability to predict how ion currents contribute to cellular electrophysiology is in turn critically dependent on our characterisation of ion channel kinetics — the voltage-dependent rates of transition between open, closed and inactivated channel states. We present a new method for rapidly exploring and characterising ion channel kinetics, applying it to the hERG potassium channel as an example, with the aim of generating a quantitatively predictive representation of the ion current. We fit a mathematical model to currents evoked by a novel 8 second sinusoidal voltage clamp in CHO cells over-expressing hERG1a. The model is then used to predict over 5 minutes of recordings in the same cell in response to further protocols: a series of traditional square step voltage clamps, and also a novel voltage clamp comprised of a collection of physiologically-relevant action potentials. We demonstrate that we can make predictive cell-specific models that outperform the use of averaged data from a number of different cells, and thereby examine which changes in gating are responsible for cell-cell variability in current kinetics. Our technique allows rapid collection of consistent and high quality data, from single cells, and produces more predictive mathematical ion channel models than traditional approaches.

Table of Contents Category

Techniques for Physiology1

Key Points

Ion current kinetics are commonly represented by current-voltage relationships, time-constant voltage relationships, and subsequently mathematical models fitted to these. These experiments take substantial time which means they are rarely performed in the same cell.

Rather than traditional square-wave voltage clamps, we fit a model to the current evoked by a novel sum-of-sinusoids voltage clamp that is only 8 seconds long.

Short protocols that can be performed multiple times within a single cell will offer many new opportunities to measure how ion current kinetics are affected by changing conditions.

The new model predicts the current under traditional square-wave protocols well, with better predictions of underlying currents than literature models. The current under a novel physiologically-relevant series of action potential clamps is predicted extremely well.

The short sinusoidal protocols allow a model to be fully fitted to individual cells, allowing us to examine cell-cell variability in current kinetics for the first time.
Visualizing Long-Term Single-Molecule Dynamics in vivo by Stochastic Protein Labeling
Authors: Liu Hui , Dong Peng , Ioannou Maria S. , Li Li , Shea Jamien , Pasolli H. Amalia , Grimm Jonathan , Rivlin Pat , Lavis Luke D. , Koyama Minoru , Liu Zhe
Published: March 2017

Our ability to unambiguously image and track individual molecules in live cells is limited by packing of multiple copies of labeled molecules within the resolution limit. Here we devise a universal genetic strategy to precisely control copy number of fluorescently labeled molecules in a cell. This system has a dynamic titration range of >10,000 fold, enabling sparse labeling of proteins expressed at different abundance levels. Combined with photostable labels, this system extends the duration of automated single-molecule tracking by 2 orders of magnitude. We demonstrate long-term imaging of synaptic vesicle dynamics in cultured neurons as well as in intact zebrafish. We found axon initial segment utilizes a ‘waterfall’ mechanism gating synaptic vesicle transport polarity by promoting anterograde transport processivity. Long-time observation also reveals that transcription factor hops between clustered binding sites in spatially-restricted sub-nuclear regions, suggesting that topological structures in the nucleus shape local gene activities by a sequestering mechanism. This strategy thus greatly expands the spatiotemporal length scales of live-cell single-molecule measurements, enabling new experiments to quantitatively understand complex control of molecular dynamics in vivo.
Pyroxasulfone resistance inLolium rigidumconferred by enhanced metabolic capacity
Authors: Busi R , Porri A , Gaines TA , Powles SB
Published: March 2017

Author Contributions

RB and AP designed and performed the experiments. RB, AP, TG, SP wrote the manuscript.

One sentence summary

This study provides novel insight into herbicide resistance conferred by GST-based detoxification to allow proactive intervention to minimize weed resistance evolution.

The evolution of herbicide-resistant weed populations in response to synthetic herbicide selective pressure is threatening safe weed control practices achieved by these molecules. In Australia multiple-resistant populations of annual ryegrass (Lolium rigidum) are effectively controlled by soil-applied herbicides which provide adequate weed control.

In this study we define the mechanistic basis of the experimentally-evolved resistance to the soil-applied herbicide pyroxasulfone in aL. rigidumpopulation. TLC and HPLC-MS provide biochemical confirmation that pyroxasulfone resistance is metabolism-based with identification and quantification of pyroxasulfone metabolites formedviaa glutathione conjugation pathway in pyroxasulfone-resistantL. rigidumplants. The observed over-expression of two putative resistance-endowingGSTgenes is consistent with pyroxasulfone-resistance in parental plants (P6) and positively correlated to pyroxasulfone resistance in F1pair-cross progenies. Thus, a major detoxification mechanism involves glutathione conjugation to pyroxasulfone andGSTover-expression in pyroxasulfone-resistantL. rigidumplants. The definition of the genetic basis of metabolic resistance in weeds can be a first crucial step towards chemical means to reverse resistance and improve long-term weed resistance management.
Pediatric Sarcoma Data Forms a Unique Cluster Measured via the Earth Mover’s Distance
Authors: Chen Yongxin , Dela Cruz Filemon , Sandhu Romeil , Kung Andrew , Mundi Prabhjot , Deasy Joseph , Tannenbaum Allen
Published: March 2017

In this note, we combined pediatric sarcoma data from Columbia University with adult sarcoma data collected from TCGA, in order to see if one can automatically discern a unique pediatric cluster in the combined data set. Using a novel clustering pipeline based on optimal transport theory, this turned out to be the case. The overall methodology may find uses for the classification of data from other biological networking problems.
Automated assembly of a reference taxonomy for phylogenetic data synthesis
Authors: Rees Jonathan A. , Cranston Karen
Published: March 2017

Taxonomy and nomenclature data are critical for any project that synthesizes biodiversity data, as most biodiversity data sets use taxonomic names to identify taxa. Open Tree of Life is one such project, synthesizing sets of published phylogenetic trees into comprehensive supertrees. No single published taxonomy met the taxonomic and nomenclatural needs of the project. Here we describe a system for reproducibly combining several source taxonomies into a synthetic taxonomy, and we discuss the challenges of taxonomic and nomenclatural synthesis for downstream biodiversity projects.
Deletion of the short N-terminal extension in OCP reveals the main site for the FRP binding
Authors: Sluchanko Nikolai N. , Slonimskiy Yury B. , Moldenhauer Marcus , Friedrich Thomas , Maksimov Eugene G.
Published: March 2017

The photoactive Orange Carotenoid Protein (OCP) plays a central role in cyanobacterial photoprotection. Photoconversion entails significant structural rearrangements in OCP required for its binding to the phycobilisome to induce excitation energy dissipation, whereas the fluorescence recovery protein (FRP) is required for OCP detachment and restoration of phycobilisome fluorescence. Although key to understanding the whole reversible mechanism of photoprotection, the FRP binding site on OCP has been representing challenge since the discovery of FRP in 2010 and is currently unknown. OCP comprises two structural domains organized into a compact basic orange form due to specific protein-chromophore and inter-domain protein-protein interactions and interacts with FRP tightly only when photoactivated. As an important stabilizing element in the orange OCP, the short αA-helix within the N-terminal extension (NTE) binds to OCP’s C-terminal domain (CTD), but unfolds upon photoactivation and interferes with phycobilisome binding. By using an alloy of biochemical and biophysical techniques, here we demonstrate that the NTE shares specific structural and functional similarities with FRP and discover the main site of OCP-FRP interactions in the OCP-CTD.
Transcription factor Wilms’ tumor 1 regulates developmental RNAs through 3′ UTR interaction
Authors: Bharathavikru Ruthrothaselvi , Dudnakova Tatiana , Aitken Stuart , Slight Joan , Artibani Mara , Hohenstein Peter , Tollervey David , Hastie Nick
Published: March 2017

Wilms’ tumor 1 (WT1) is essential for the development and homeostasis of multiple mesodermal tissues. Despite evidence for post-transcriptional roles, no endogenous WT1 target RNAs exist. Using RNA immunoprecipitation and UV cross-linking, we show that WT1 binds preferentially to 3′ untranslated regions (UTRs) of developmental targets. These target mRNAs are down-regulated upon WT1 depletion in cell culture and developing kidney mesenchyme. Wt1 deletion leads to rapid turnover of specific mRNAs. WT1 regulates reporter gene expression through interaction with 3′ UTR-binding sites. Combining experimental and computational analyses, we propose that WT1 influences key developmental and disease processes in part through regulating mRNA turnover.
Oncogenic Kras drives invasion and maintains metastases in colorectal cancer
Authors: Boutin Adam T. , Liao Wen-Ting , Wang Melody , Hwang Soyoon Sarah , Karpinets Tatiana V. , Cheung Hannah , Chu Gerald C. , Jiang Shan , Hu Jian , Chang Kyle , Vilar Eduardo , Song Xingzhi , Zhang Jianhua , Kopetz Scott , Futreal Andrew , Wang Y. Alan , Kwong Lawrence N. , DePinho Ronald A.
Published: March 2017

Human colorectal cancer (CRC) is a major cause of cancer mortality and frequently harbors activating mutations in the KRAS gene. To understand the role of oncogenic KRAS in CRC, we engineered a mouse model of metastatic CRC that harbors an inducible oncogenic Kras allele (Krasmut) and conditional null alleles of Apc and Trp53 (iKAP). The iKAP model recapitulates tumor progression from adenoma through metastases. Whole-exome sequencing revealed that the Krasmut allele was heterogenous in primary tumors yet homogenous in metastases, a pattern consistent with activated Krasmut signaling being a driver of progression to metastasis. System-level and functional analyses revealed the TGF-β pathway as a key mediator of Krasmut-driven invasiveness. Genetic extinction of Krasmut resulted in specific elimination of the Krasmut subpopulation in primary and metastatic tumors, leading to apoptotic elimination of advanced invasive and metastatic disease. This faithful CRC model provides genetic evidence that Krasmut drives CRC invasion and maintenance of metastases.
X-ray investigation of strained epitaxial layer systems by reflections in skew geometry
Authors: Zaumseil Peter
Published: March 2017

Four different SiGe/Si layer structures, pseudomorphically grown and (partially) relaxed, are used as examples to demonstrate that reflections in symmetric skew geometry can successfully be used to realize a complex analysis of these systems. Taking the intensity exactly along the truncation rod of a reciprocal lattice point, it is possible to simulate this diffraction curve and determine the layer parameter in the projection according to the netplane tilt relative to the surface. The main precondition for this technique and for performing reciprocal space mapping with sufficiently high resolution is a low angular divergence of the incident and detected beams perpendicular to the diffraction plane, which can also be achieved by suitable optical elements on laboratory-based diffractometers.
1,3,5-Tri(iodoethynyl)-2,4,6-trifluorobenzene: halogen-bonded frameworks and NMR spectroscopic analysis
Authors: Szell Patrick M. J. , Gabidullin Bulat , Bryce David L.
Published: March 2017

Halogen bonding is the non-covalent interaction between the region of positive electrostatic potential associated with a covalently bonded halogen atom, named the σ-hole, and a Lewis base. Single-crystal X-ray diffraction structures are reported for a series of seven halogen-bonded cocrystals featuring 1,3,5-tris(iodoethynyl)-2,4,6-trifluorobenzene (1) as the halogen-bond donor, and bromide ions (as ammonium or phosphonium salts) as the halogen-bond acceptors: (1)·MePh3PBr, (1)·EtPh3PBr, (1)·acetonyl-Ph3PBr, (1)·Ph4PBr, (1)·[bis(4-fluorophenyl)methyl]triphenylphosphonium bromide, and two new polymorphs of (1)·Et3BuNBr. The cocrystals all feature moderately strong iodine–bromide halogen bonds. The crystal structure of pure [bis(4-fluorophenyl)methyl]triphenylphosphonium bromide is also reported. The results of a crystal engineering strategy of varying the size of the counter-cation are explored, and the features of the resulting framework materials are discussed. Given the potential utility of (1) in future crystal engineering applications, detailed NMR analyses (in solution and in the solid state) of this halogen-bond donor are also presented. In solution, complex13C and19F multiplets are explained by considering the delicate interplay between variousJcouplings and subtle isotope shifts. In the solid state, the formation of (1)·Et3BuNBr is shown through significant13C chemical shift changes relative to pure solid 1,3,5-tris(iodoethynyl)-2,4,6-trifluorobenzene.
Taking the halogen bonding–hydrogen bonding competition one step further: complexes of difluoroiodomethane with trimethylphosphine, dimethyl sulfide and chloromethane
Authors: Geboes Yannick , De Proft Frank , Herrebout Wouter A.
Published: March 2017

To rationalize the driving factors in the competition of halogen bonding and hydrogen bonding, the complexes of the combined halogen-/hydrogen-bond donor difluoroiodomethane with the Lewis bases trimethylphosphine, dimethyl sulfide and chloromethane are studied. For all Lewis bases,ab initiocalculations lead to halogen- and hydrogen-bonded complexes. Fourier transform–IR experiments involving solutions of mixtures of difluoroiodomethane with trimethylphosphine(-d9) or dimethyl sulfide(-d6) in liquid krypton confirm the coexistence of a halogen-bonded and hydrogen-bonded complex. Also for solutions containing chloromethane, evidence of the formation of binary associations is found, but no definitive assignment of the multiple complex bands could be made. Using van't Hoff plots, the experimental complexation enthalpies for the halogen- and hydrogen-bonded complex of difluoroiodomethane with trimethylphosphine are determined to be −15.4 (4) and −10.5 (3) kJ mol−1, respectively, while for the halogen- and hydrogen-bonded complexes with dimethyl sulfide, the values are −11.3 (5) and −7.7 (6) kJ mol−1, respectively. The experimental observation that for both trimethylphospine and dimethyl sulfide the halogen-bonded complex is more stable than the hydrogen-bonded complex supports the finding that softer Lewis bases tend to favor iodine halogen bonding over hydrogen bonding.
Cyclic networks of halogen-bonding interactions in molecular self-assemblies: a theoretical N—X...NversusC—X...N investigation
Authors: Parra Ruben D. , Castillo Álvaro
Published: March 2017

The geometries and energetics of molecular self-assembly structures that contain a sequential network of cyclic halogen-bonding interactions are investigated theoretically. The strength of the halogen-bonding interactions is assessed by examining binding energies, electron charge transfer (NBO analysis) and electron density at halogen-bond critical points (AIM theory). Specifically, structural motifs having intramolecular N—X...N (X= Cl, Br, or I) interactions and the ability to drive molecular self-assemblyviathe same type of interactions are used to construct larger self-assemblies of up to three unit motifs. N—X...N halogen-bond cooperativity as a function of the self-assembly size, and the nature of the halogen atom is also examined. The cyclic network of the halogen-bonding interactions provides a suitable cavity rich in electron density (from the halogen atom lone pairs not involved in the halogen bonds) that can potentially bind an electron-deficient species such as a metal ion. This possibility is explored by examining the ability of the N—X...N network to bind Na+. Likewise, molecular self-assembly structures driven by the weaker C—X...N halogen-bonding interactions are investigated and the results compared with those of their N—X...N counterparts.
Crystal and molecular structure of (2Z,5Z)-3-(2-methoxyphenyl)-2-[(2-methoxyphenyl)imino]-5-(4-nitrobenzylidene)thiazolidin-4-one
Authors: Djafri Ahmed , Chouaih Abdelkader , Daran Jean-Claude , Djafri Ayada , Hamzaoui Fodil
Published: March 2017

In the title compound, C24H19N3O5S, the thiazole ring (r.m.s. deviation = 0.012 Å) displays a planar geometry and is surrounded by three fragments, two methoxyphenyl and one nitrophenyl. The thiazole ring is almost in the same plane as the nitrophenyl ring, making a dihedral angle of 20.92 (6)°. The two methoxyphenyl groups are perpendicular to the thiazole ring [dihedral angles of 79.29 (6) and 71.31 (7)° and make a dihedral angle of 68.59 (7)°. The molecule exists in anZ,Zconformation with respect to the C=N imine bond. In the crystal, a series of C—H...N, C—H...O and C—H...S hydrogen bonds, augmented by several π–π(ring) interactions, produce a three-dimensional architecture of molecules stacked along theb-axis direction. The experimentally derived structure is compered with that calculated theoretically using DFT(B3YLP) methods.
Crystal structure of Pigment Red 254 from X-ray powder diffraction data
Authors: Ivashevskaya Svetlana N.
Published: March 2017

The crystal structure of Pigment Red 254 [P.R. 254, C18H10Cl2N2O2; systematic name: 3,6-bis(4-chlorophenyl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione] was solved from laboratory X-ray powder diffraction data using the simulated annealing method followed by Rietveld refinement because the very low solubility of the pigment in all solvents impedes the growth of single crystals suitable for X-ray analysis. The molecule lies across an inversion center. The dihedral angle between the benzene ring and the pyrrole ring in the unique part of the molecule is 11.1 (2)°. In the crystal, molecules are linkedviaN—H...O hydrogen bonds, forming chains along [110] incorporatingR22(8) rings.
Interaction between maleic acid andN-R-furfurylamines: crystal structure of 2-methyl-N-[(5-phenylfuran-2-yl)methyl]propan-2-aminium (2Z)-3-carboxyacrylate andN-[(5-iodofuran-2-yl)methyl]-2-methylpropan-2-aminium (2Z)-3-carboxyprop-2-enoate
Authors: Kvyatkovskaya Elisaveta A. , Zaytsev Vladimir P. , Zubkov Fedor I. , Dorovatovskii Pavel V. , Zubavichus Yan V. , Khrustalev Victor N.
Published: March 2017

The title molecular salts, C15H20NO+·C4H3O4−, (I), and C9H15INO+·C4H3O4−, (II), have very similar molecular geometries for both cation and anion. The anions of both (I) and (II) are practically planar (r.m.s. deviations = 0.062 and 0.072 Å, respectively) and adopt a rare symmetrical geometry with the hydroxy H atom approximately equidistant from the two O atoms. In their crystals, the cations and anions in both (I) and (II) form tight ionic pairsviastrong N—H...O hydrogen bonds, with a roughly perpendicular disposition of the anion to the furan ring of the cation. This ion-pair conformation appears to correlate with the lack of reactivity of these salts in [4 + 2] cycloaddition reactions. In the extended structures of (I) and (II), the ion pairs form hydrogen-bonded chains propagating along [010] and [001], respectively,viaN—H...O hydrogen bonds.
Crystal structure of methyl (4R)-4-(4-methoxybenzoyl)-4-{[(1R)-1-phenylethyl]carbamoyl}butanoate
Authors: Manchado Alejandro , Salgado Mateo M. , Vicente Álvaro , Díez David , Sanz Francisca , Garrido Narciso M.
Published: March 2017

The title compound, C22H25NO5, was prepared by CAN [cerium(IV) ammonium nitrate] oxidation of the corresponding β-lactam. The dihedral angle between the benzene rings is 13.3 (4)° and the C—N—C(=O)—C torsion angle is 176.1 (6)°. In the crystal, amide-C(4) N—H...O and reinforcing C—H...O hydrogen bonds link the molecules into infinite [010] chains. Further C—H...O hydrogen bonds cross-link the chains in thec-axis direction.
Tricaesium citrate monohydrate, Cs3C6H5O7·H2O: crystal structure and DFT comparison
Authors: Rammohan Alagappa , Sarjeant Amy A. , Kaduk James A.
Published: March 2017

The crystal structure of tricaesium citrate monohydrate, 3Cs+·C6H5O73−·H2O, has been solved and refined using laboratory X-ray single-crystal diffraction data, and optimized using density functional techniques. This compound is isostructural to the K+and Rb+compounds with the same formula. The three independent Cs cations are eight-, eight-, and seven-coordinate, with bond-valence sums of 0.91, 1.22, and 1.12 valence units. The coordination polyhedra link into a three-dimensional framework. The hydroxy group forms the usualS(5) hydrogen bond with the central carboxylate group, and the water molecule acts as a donor in two strong hydrogen bonds.
Improving the accuracy of time-harmonic FE simulations in induction heating applications
Authors: McMeekin Kevin , Sirois Frédéric , Tousignant Maxime , Bocher Philippe
Published: March 2017

Purpose

Surface heat treatment by induction heating (10-100 kHz) requires precise prediction and control of the depth of the induced phase transformation. This paper aims at identifying common issues with the measurement and modeling of magnetic properties used in induction heating simulations, and it proposes ways to improve the situation.

Design/methodology/approach

In particular, it is demonstrated how intrinsic magnetic properties (i.e. the B-H curve) of a sample can change during the magnetic characterization process itself, due to involuntary annealing of the sample. Then, for a B-H curve that is supposed perfectly known, a comparison is performed between multiple models, each one representing the magnetic properties of steel in time-harmonic (TH) finite element method simulations. Finally, a new model called “power-equivalent model” is proposed. This model provides the best possible accuracy for a known nonlinear and hysteretic B-H curve used in TH simulations.

Findings

By carefully following the guidelines identified in this paper, reduction of errors in the range of 5-10 per cent can be achieved, both at the experimental and modeling levels. The new “power-equivalent model” proposed is also expected to be more generic than existing models.

Originality/value

This paper highlights common pitfalls in the measurement and modeling of magnetic properties, and suggests ways to improve the situation.
Improved Litz wire manufacture process using resonant power converter-based induction heating
Authors: Naval Alejandro , Sarnago Hector , Lope Ignacio , Lucia Oscar , Burdio José M.
Published: March 2017

Purpose

Litz wire manufacturing using mechanical procedures presents several limitations regarding reliability and repeatability, especially when a small strand diameter is used. This paper aims to propose a power supply design for Litz wire manufacturing using a high-frequency high-performance resonant converter.

Design/methodology/approach

This paper proposes the design of a resonant power supply for induction heating specially designed to tackle with the challenge of heating Litz wires quickly.

Findings

The proposed converter enables the removal of the isolating coating from the Litz wire through induction heating, improving significantly the manufacturing process.

Originality/value

The proposed converter improves significantly the manufacturing process of Litz wire through induction heating, with economic and reliability benefits.
Induction heating in estimation of thermal properties of conductive materials
Authors: Zgraja Jerzy , Cieslak Adam
Published: March 2017

Purpose

The purpose of the research was to develop a method for the determination of temperature characteristics of thermal diffusivity and specific heat on a single and the same stand, powered from an inverter for induction heating. Determination of the thermal diffusivity has been based on the idea of the pulse method. Searched solutions allowed to reduce inaccuracy of the pulse method when such an unusual source of pulse of energy is used.

Design/methodology/approach

Coupled electromagnetic and thermal calculations were carried out to verify proposed methods for estimating thermal properties of an induction heated charge. Presented methods were applied into a real laboratory stand and they were examined experimentally.

Findings

Achieved results of calculations allow to estimate thermal properties of the induction heated charge with 2 and 5 per cent of uncertainty, respectively, for heat capacity and thermal diffusivity. It gives possibility to use results as an input for further proceedings connected with estimation of electrical parameters in a more complex system.

Practical implications

Presented methods of estimating thermal properties of the induction heated charge were verified experimentally on a dedicated laboratory stand. It gives a practical possibility to implement previously established assumptions and examine them. This is a significant step toward the construction of an easy-to-use device for a comprehensive determination of material parameters of metals directly in the heat treatment plant.

Originality/value

This study presents a trial of implementation of induction heating as a source of energy in the impulse method for estimation of thermal properties of the material. Additionally, it presents a process of improving results achieved with the flash methods which were presented in previous papers. The method of estimation of specific heat which uses induction heating as the heat source was presented too.
Design concepts of induction mass heating technology based on multiple-criteria optimization
Authors: Pleshivtseva Yuliya , Rapoport Edgar , Nacke Bernard , Nikanorov Alexander , Di Barba Paolo , Forzan Michele , Lupi Sergio , Sieni Elisabetta
Published: March 2017

Purpose

The purpose of this paper is to describe main ideas and demonstrate results of the research activities carried out by the authors in the field of design concepts of induction mass heating technology based on multiple-criteria optimization. The main goal of the studies is the application of different optimization methods and numerical finite element method (FEM) codes for field analysis to solve the multi-objective optimization problem that is mathematically formulated in terms of the most important optimization criteria, for example, maximum temperature uniformity, maximum energy efficiency and minimum scale formation.

Design/methodology/approach

Standard genetic algorithm (GA), non-dominated sorting genetic algorithm (NSGA) and alternance method of parametric optimization based on the optimal control theory are applied as effective tools for the practice-oriented problems for multiple-criteria optimization of induction heaters’ design based on non-linear coupled electromagnetic and temperature field analysis. Different approaches are used for combining FEM codes for interconnected field analysis and optimization algorithms into the automated optimization procedure.

Findings

Optimization procedures are tested and investigated for two- and three-criteria optimization problems solution on the examples of induction heating of a graphite disk, induction heating of aluminum and steel billets prior to hot forming.

Practical implications

Solved problems are based on the design of practical industrial applications. The developed optimization procedures are planned to be applied to the wide range of real-life problems of the optimal design and control of different electromagnetic devices and systems.

Originality/value

The paper describes main ideas and results of the research activities carried out by the authors during past years in the field of multiple-criteria optimization of induction heaters’ design based on numerical coupled electromagnetic and temperature field analysis. Implementing the automated procedure that combines a numerical FEM code for coupled field analysis with an optimization algorithm and its subsequent application for designing induction heaters makes the proposed approach specific and original. The paper also demonstrates that different optimization strategies used (standard GA, NSGA-II and the alternance method of optimal control theory) are effective for real-life industrial applications for multiple-criteria optimization of induction heaters design.
Inverse technique for determining temperature dependence of material properties
Authors: Pánek David , Kotlan Václav , Hamar Roman , Doležel Ivo
Published: March 2017

Purpose

This paper aims to present a methodology of finding temperature dependencies of selected physical parameters of metals. The method is based on the combination of measurement of the surface temperature of material during the process of heating and subsequent solution of the inverse problem using multi-parametric optimization.

Design/methodology/approach

The methodology is based on measurements and numerical solution of the forward and inverse problem, taking into account all involved nonlinearities (saturation curve of the processed steel material and temperature dependences of its physical parameters). The inverse problem is solved by a genetic algorithm.

Findings

The suggested methodology was successfully verified on several metal materials whose temperature-dependent parameters are known. The calculated and measured results exhibit a very good accordance (the differences do not exceed about 10 per cent for room and higher temperatures).

Research limitations/implications

At this moment, the methodology successfully works when the temperature dependence of just one material parameter is to be found (which means that the temperature dependencies of other parameters are known). The accuracy of results also depends on the correctness of other input data.

Practical implications

This paper provides a relatively easy possibility of finding the temperature dependencies of thermal conductivity or heat capacity of various alloys.

Originality/value

The paper proposes a methodology of finding the temperature dependence of a given material parameter that is not known in advance (which is of great importance in case of alloys).
Emissivity compensated infrared thermometry for planar materials
Authors: Osta Marta , Carretero Claudio , Blasco Pilar , Carretero Enrique , Alonso Rafael
Published: March 2017

Purpose

This paper aims to analyze the conical-shaped compensator applied to infrared (IR) thermometry for planar materials.

Design/methodology/approach

The compensator for the IR thermometry system has been analyzed by means of numerical simulations performed in a commercial finite element analysis tool. Afterwards, the characteristics of a final system have been proposed. The simulation results have been validated by means of experimental measurements performed in a prototype of the proposed system.

Findings

The proposed conical shape geometry of the compensator is suitable to reduce the errors associated with the temperature estimation by IR thermometry when emissivity of the material is not known with adequate accuracy.

Practical implications

This work proposed an arrangement of conical-shaped compensator to increase the precision in the IR radiation thermometry of planar materials.

Originality/value

In this paper, the conical shape geometry is proposed instead of the classical semi-spherical geometry for the compensator of an IR radiation thermometry system with the purpose of reducing the thickness of the complete system. This new proposal can be advantageous when geometrical constraints are imposed.
Numerical modelling of induction heated multi-zones rubber vulcanization process
Authors: Ebel Wladimir , Nikanorov Alexander , Baake Egbert
Published: March 2017

Purpose

The purpose of this paper is to research a multi-zone rubber vulcanization process heated by induction.

Design/methodology/approach

The design is an abstract setup model with two zones, where the homogene rubber compound is heated with different regimes. Simulation is completely done in ANSYS Mechanical by the finite element method solution. The research is made mostly simulative.

Findings

The results show that it is possible to obtain a factor-three vulcanization level difference in a core of a 20-mm rubber plate in a distance of less than 60 mm, while the heating is done from the side of the surface.

Originality/value

The originality is the combination of rubber vulcanization with a dynamic heat source in a form of electromagnetic induction applied on the mold form. This allows a high level of control of the vulcanization process of the rubber compound.
Stereotype threat effects on African American and Latina/o Elementary students tested together
Authors: Wasserberg Martin James
Published: March 2017

Purpose

This study aimed to investigate whether a diagnostic testing condition leads to stereotype threat effects for African American and Latina/o children (N= 81) when tested together at an urban elementary school in Miami, Florida.

Design/methodology/approach

To analyze the effect of stereotype threat on participants’ reading test performance, a 2 (race/ethnicity) × 2 (test condition) ANOVA was conducted.

Findings

Results indicated that presenting a reading test as diagnostic of abilities hindered the performance of African American children but not of Latina/o children.

Practical Implications

A relationship to Latina/o racial identity is explored as well as suggestions for developing interventions capable of attenuating stereotype threat effects for African American children.

Originality/value

In past research, Latina/o children have been demonstrated to be negatively affected by stereotype threat when tested alone or in the presence of a White comparison group (McKown and Weinstein, 2003; Nader and Clark, 2011). However, the Latina/o participants in this study, tested with an African American comparison group, were unaffected by stereotype threat trending toward experiencing stereotype lift. The present findings posit questioning as to whether Latina/o racial identity moderates stereotype threat effects and how it plays out in elementary schools.
Linguistic hegemony today: recommendations for eradicating language discrimination
Authors: Scott Lakia M. , Venegas Elena M.
Published: March 2017

Purpose

The purpose of this paper is to discuss issues of contemporary language conflict in educational contexts.

Design/methodology/approach

This is a conceptual paper which examines current educational practices and policies through the lens of linguistic hegemony.

Findings

The authors identify three primary areas in which linguistic hegemony persists at present, including English-only policies, varied perspectives on language difference and harsh graduation mandates.

Originality/value

The authors extend upon Antonio Gramsci’s notion of hegemonic culture as well as Robert Phillipson’s concept of linguistic imperialism in identifying current instances of linguistic hegemony in educational policies and practices throughout the USA.