bluuebunny/crossref_metadata_2025 huggingface dataset:
Defects and disorder in carbon nanotubes
Authors: Collins Philip G.
Published: August 2017

This article examines the physical consequences of defects and disorder in carbon nanotubes (CNTs). It begins with a pedagogical categorization of the types of defects and disorder found in CNTs, including lattice vacancies and bond rotations, and goes on to discuss considers two primary sources of disorder: the environment surrounding a CNT and the substrate supporting it. It then considers various experimental methods for locating defects in CNTs, including atomic-resolution scanning tunnelling microscopy, transmission electron microscopy, electrochemical and chemoselective labelling, optical spectroscopy, and electrical conductance. The article concludes with a review of the long-range consequences of defects and disorder on the physical properties of CNTs such as chemical reactivity, electrical transport, and mechanical effects.
Magnetic properties of nanoparticles
Authors: Mørup Steen , Frandsen Cathrine , Hansen Mikkel F.
Published: August 2017

This article discusses the magnetic properties of nanoparticles. It first considers magnetic domains and the critical size for single-domain behavior of magnetic nanoparticles before providing an overview of magnetic anisotropy in nanoparticles. It then examines magnetic dynamics in nanoparticles, with particular emphasis on superparamagnetic relaxation and the use of Mössbauer spectroscopy, dc magnetization measurements, and ac susceptibility measurements for studies of superparamagnetic relaxation. It also describes magnetic dynamics below the blocking temperature, magnetic interactions between nanoparticles, and fluctuations of the magnetization directions. Finally, it analyzes the magnetic structure of nanoparticles, focusing on magnetic phase transitions and surface effects, non-collinear spin structures, and magnetic moments of antiferromagnetic nanoparticles.
Order and Disorder in the Extracellular Matrix
Authors: van der Horst Astrid , Wuite Gijs J. L.
Published: August 2017

This article examines order and disorder in the extracellular matrix (ECM). The mechanical and structural properties of the tissues in the human body are largely determined by the ECM, the fibrillar network of proteins surrounding the cells. The main component of the ECM is collagen, which self-assembles in vivo into fibrils and fibers that supply rigidity and tensile strength to the ECM. The protein is often found together with elastin, another self-assembling ECM scleroprotein, whose properties of elasticity, extensibility, and elastic recoil supplement the mechanical properties of collagen. This article first provides an overview of protein synthesis and structure, with particular emphasis on tropocollagen, tropoelastin, and recombinantly-made polypeptides. It then considers the hierarchical supramolecular organization of the ECM, collagen and elastin before concluding with an assessment of structure-function relations at the matrix level.
Biological Fluid Interfaces and Membranes
Authors: Brown Aidan T. , Cicuta Pietro
Published: August 2017

This article examines the properties of biological fluid interfaces and membranes, with particular emphasis on monolayers and bilayers. There are several examples of interfaces between biological fluids; the most relevant to human physiology are probably the liquid/air interfaces in the lungs and on the surface of the eyes. Both of these feature films with remarkable properties of compressibility and self-healing. After providing an overview of the constituent molecules of biological interfaces, this article reviews the current knowledge on surface films and membranes, giving context for their role in biology, but paying special attention to the basic physical ideas that underpin fundamental studies of in-vitro model systems. It also considers isolated membranes, characterized by tension, elasticity and viscous damping, as well as closed vesicles and cells where the membrane separates the cytoskeleton from the extracellular matrix.
Surfactants
Authors: Langevin Dominique
Published: August 2017

This article discusses the principles and action of surfactants, with particular emphasis on the most general case of small surfactant molecules with long hydrocarbon chains. Surfactants, also called amphiphilic molecules, are an essential part of many soft condensed matter systems where their basic role is to stabilize interfaces between different component materials. These molecules have a tendency to adsorb at interfaces between water and apolar media, solids, liquids, or air. This article begins with an overview of surface tension and surface rheology before turning to bulk aggregates such as micelles. It then describes microemulsions, non-equilibrium systems, emulsions and foams as well as the structure and mechanical characteristics of interfaces, individually and macroscopically (in emulsions and foams), and on the structures formed by surfactant aggregation into micelles and microemulsions. It also examines the case of adsorption at fluid surfaces, such as air–water and oil–water interfaces.
Liquid Crystals
Authors: Lavrentovich Oleg D.
Published: August 2017

This article discusses modern directions of research in liquid crystals (LCs). LCs represent one of the best studied classes of soft matter, along with colloids, polymer solutions and melts, gels, and foams. Phenomena observed in LCs and approaches developed for their description become of heuristic value in other branches of science. This article considers the basic properties of low-molecular weight thermotropic LCs, with an additional emphasis on the developments of the last decade, such as LC colloids. It begins with an overview of thermotropic and lyotropic systems, followed by a review of the concept of order parameter, elasticity, surface anchoring, and topological defects. It also evaluates hybrid systems combining LCs with polymers or colloids, along with new ways of creating mesomorphic systems and the dynamics of LCs, including anisotropic viscosity, director dynamics and the Frederiks transition, and flow induced by thermal expansion. Finally, it describes various applications of LCs.
Physics of Granular Systems
Authors: Blumenfeld Raphael , Edwards Sam F. , Walley Stephen M.
Published: August 2017

This article discusses the fundamental physics of granular systems. It begins with an overview of the science of granular matter, followed by a description of the ‘micro’-structure on the granular level. It then considers stress transmission in mechanically equilibrated granular assemblies, focusing on conditions for marginal rigidity, isostaticity theory, and limitations of linear stress theories. It also examines the use of statistical mechanics to analyse and classify granular materials, taking into account the micro-canonical volume ensemble, structural degrees of freedom, the canonical volume ensemble and the quasi-particles of the volume ensemble, the stress ensemble, and the relationship between the volume and stress ensembles. The article concludes with an assessment of recent advances in the ongoing attempt to construct a statistical mechanical theory of granular systems.
Dynamics of Entangled Polymers
Authors: Larson Ronald G. , Wang Zuowei
Published: August 2017

This article explores the dynamics of entangled polymers, with particular emphasis on how the unusual and often dramatic mechanical properties of concentrated polymer systems are determined by the physics of entanglements. It begins with an overview of the foundations of entangled polymer dynamics, organized around tubes and slip links used in modeling entanglements, the packing length and concentration effects, the results of computer simulations on entanglements, topological contacts, and the effects of large deformations. The focus is on the nature of ‘entanglement’, both from a bottom-up molecular view, and from a phenomenological one. The discussion then turns to the linear viscoelasticity of entangled polymer solutions and melts, along with nonlinear viscoelasticity. Models of polymer dynamics in the linear regime are also described, including the ‘standard tube model’. The article concludes with suggestions for future work.
Locomotor Training and Strength and Balance Exercises for Walking Recovery After Stroke: Response to Number of Training Sessions
Authors: Rose Dorian K. , Nadeau Stephen E. , Wu Samuel S. , Tilson Julie K. , Dobkin Bruce H. , Pei Qinglin , Duncan Pamela W.
Published: August 2017

Background

Evidence-based guidelines are needed to inform rehabilitation practice, including the effect of number of exercise training sessions on recovery of walking ability after stroke.

Objective

The objective of this study was to determine the response to increasing number of training sessions of 2 interventions—locomotor training and strength and balance exercises—on poststroke walking recovery.

Design

This is a secondary analysis of the Locomotor Experience Applied Post-Stroke (LEAPS) randomized controlled trial.

Setting

Six rehabilitation sites in California and Florida and participants’ homes were used.

Participants

Participants were adults who dwelled in the community (N=347), had had a stroke, were able to walk at least 3 m (10 ft) with assistance, and had completed the required number of intervention sessions.

Intervention

Participants received 36 sessions (3 times per week for 12 weeks), 90 minutes in duration, of locomotor training (gait training on a treadmill with body-weight support and overground training) or strength and balance training.

Measurements

Talking speed, as measured by the 10-Meter Walk Test, and 6-minute walking distance were assessed before training and following 12, 24, and 36 intervention sessions.

Results

Participants at 2 and 6 months after stroke gained in gait speed and walking endurance after up to 36 sessions of treatment, but the rate of gain diminished steadily and, on average, was very low during the 25- to 36-session epoch, regardless of treatment type or severity of impairment.

Limitations

Results may not generalize to people who are unable to initiate a step at 2 months after stroke or people with severe cardiac disease.

Conclusions

In general, people who dwelled in the community showed improvements in gait speed and walking distance with up to 36 sessions of locomotor training or strength and balance exercises at both 2 and 6 months after stroke. However, gains beyond 24 sessions tended to be very modest. The tracking of individual response trajectories is imperative in planning treatment.
Efficacy of Leaf Oil from Pimenta racemosa var. racemosa in Controlling Bacterial Wilt of Tomato
Authors: Deberdt Péninna , Davezies Isabelle , Coranson-Beaudu Régine , Jestin Alexandra
Published: August 2017

Bacterial wilt, caused by Ralstonia solanacearum, is a major plant disease throughout the Caribbean. The ability of the essential oil from Pimenta racemosa var. racemosa to control bacterial wilt of tomato (R. solanacearum, phylotype IIB/4NPB) was investigated. Lemongrass (chemotype 1)-, aniseed (chemotype 2)-, and clove (chemotype 3)-scented chemotypes of P. racemosa var. racemosa essential oil were tested. Six concentrations of emulsified essential oil (from 0.01 to 0.14% [v/v]) were evaluated by in vitro culture amendment assays and by in vivo experiments in greenhouse. Chemotype 3 displayed remarkable in vitro antibacterial activity against R. solanacearum, because the minimum inhibitory concentration was only 0.03%, compared with 0.14% for chemotypes 1 and 2. In greenhouse experiments, no incidence of bacterial wilt was observed in tomato plants grown in soil treated with chemotype 3 of P. racemosa var. racemosa at a concentration of 0.14%. In the untreated control soil, 62% of plants displayed symptoms of bacterial wilt. Treatment with chemotype 3 significantly increased the growth of tomato plants compared with untreated controls. These results suggest that chemotype 3 of P. racemosa var. racemosa essential oil is a good candidate for further development as a soil biofumigant for the control of tomato bacterial wilt.
Stable isotope analyses of feather amino acids identify penguin migration strategies at ocean basin scales
Authors: Polito Michael J. , Hinke Jefferson T. , Hart Tom , Santos Mercedes , Houghton Leah A. , Thorrold Simon R.
Published: August 2017

Identifying the at-sea distribution of wide-ranging marine predators is critical to understanding their ecology. Advances in electronic tracking devices and intrinsic biogeochemical markers have greatly improved our ability to track animal movements on ocean-wide scales. Here, we show that, in combination with direct tracking, stable carbon isotope analysis of essential amino acids in tail feathers provides the ability to track the movement patterns of two, wide-ranging penguin species over ocean basin scales. In addition, we use this isotopic approach across multiple breeding colonies in the Scotia Arc to evaluate migration trends at a regional scale that would be logistically challenging using direct tracking alone.
How pigeons couple three-dimensional elbow and wrist motion to morph their wings
Authors: Stowers Amanda K. , Matloff Laura Y. , Lentink David
Published: August 2017

Birds change the shape and area of their wings to an exceptional degree, surpassing insects, bats and aircraft in their ability to morph their wings for a variety of tasks. This morphing is governed by a musculoskeletal system, which couples elbow and wrist motion. Since the discovery of this effect in 1839, the planar ‘drawing parallels’ mechanism has been used to explain the coupling. Remarkably, this mechanism has never been corroborated from quantitative motion data. Therefore, we measured how the wing skeleton of a pigeon (Columba livia) moves during morphing. Despite earlier planar assumptions, we found that the skeletal motion paths are highly three-dimensional and do not lie in the anatomical plane, ruling out the ‘drawing parallels’ mechanism. Furthermore, micro-computed tomography scans in seven consecutive poses show how the two wrist bones contribute to morphing, particularly the sliding ulnare. From these data, we infer the joint types for all six bones that form the wing morphing mechanism and corroborate the most parsimonious mechanism based on least-squares error minimization. Remarkably, the algorithm shows that all optimal four-bar mechanisms either lock, are unable to track the highly three-dimensional bone motion paths, or require the radius and ulna to cross for accuracy, which is anatomically unrealistic. In contrast, the algorithm finds that a six-bar mechanism recreates the measured motion accurately with a parallel radius and ulna and a sliding ulnare. This revises our mechanistic understanding of how birds morph their wings, and offers quantitative inspiration for engineering morphing wings.
The relative compliance of energy-storing tendons may be due to the helical fibril arrangement of their fascicles
Authors: Shearer Tom , Thorpe Chavaunne T. , Screen Hazel R. C.
Published: August 2017

A nonlinear elastic microstructural model is used to investigate the relationship between structure and function in energy-storing and positional tendons. The model is used to fit mechanical tension test data from the equine common digital extensor tendon (CDET) and superficial digital flexor tendon (SDFT), which are used as archetypes of positional and energy-storing tendons, respectively. The fibril crimp and fascicle helix angles of the two tendon types are used as fitting parameters in the mathematical model to predict their values. The outer fibril crimp angles were predicted to be 15.1° ± 2.3° in the CDET and 15.8° ± 4.1° in the SDFT, and the average crimp angles were predicted to be 10.0° ± 1.5° in the CDET and 10.5° ± 2.7° in the SDFT. The crimp angles were not found to be statistically significantly different between the two tendon types (p= 0.572). By contrast, the fascicle helix angles were predicted to be 7.9° ± 9.3° in the CDET and 29.1° ± 10.3° in the SDFT and were found to be statistically highly significantly different between the two tendon types (p< 0.001). This supports previous qualitative observations that helical substructures are more likely to be found in energy-storing tendons than in positional tendons and suggests that the relative compliance of energy-storing tendons may be directly caused by these helical substructures.
Biophysical properties of the human finger for touch comprehension: influences of ageing and gender
Authors: Abdouni A. , Djaghloul M. , Thieulin C. , Vargiolu R. , Pailler-Mattei C.  , Zahouani H.
Published: August 2017

The human finger plays an extremely important role in tactile perception, but little is known about how age and gender affect its biophysical properties and their role in tactile perception. We combined studies on contact characteristics, mechanical properties and surface topography to understand age and gender effects on the human finger. The values obtained regarding contact characteristics (i.e. adhesive force) were significantly higher for women than for men. As for mechanical properties (i.e. Young's modulus
E
), a significant and positive correlation with age was observed and found to be higher for women. A positive correlation was observed between age and the arithmetic mean of surface roughness for men. However, an inverse age effect was highlighted for women. The age and gender effects obtained have never been reported previously in the literature. These results open new perspectives for understanding the weakening of tactile perception across ages and how it differs between men and women.
Development of a novel and cost-effective redox sensor for voltammetric determination of pantoprazole sodium during pharmacokinetic studies
Authors: Khashaba Pakinaz Y. , Ali Hassan Refat H. , El-wekil Mohamed M.
Published: August 2017

A pencil graphite electrode modified with poly (bromocresol green (BCG)) was prepared by electro-polymerization process for the determination of pantoprazole sodium. The surface morphology and structure of poly (BCG) film were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. The determination of pantoprazole sodium in Britton–Robinson buffer (pH 7.0) was carried out by square wave adsorptive stripping voltammetric technique. Under optimum conditions, the linear response of the peak with concentration of the cited drug was in the range of 6.6–360 × 10−8 M with limit of detection of 2.2 × 10−8 M. Moreover, the poly (BCG)-modified electrode has been successfully applied to determine pantoprazole sodium in tablets, vials and during pharmacokinetic studies.
A mix-and-click method to measure amyloid-β concentration with sub-micromolar sensitivity
Authors: Xue Christine , Lee Yoon Kyung , Tran Joyce , Chang Dennis , Guo Zhefeng
Published: August 2017

Aggregation of amyloid-β (Aβ) protein plays a central role in Alzheimer's disease. Because protein aggregation is a concentration-dependent process, rigorous investigations require accurate concentration measurements. Owing to the high aggregation propensity of Aβ protein, working solutions of Aβ are typically in the low micromolar range. Therefore, an ideal Aβ quantification method requires high sensitivity without sacrificing speed and accuracy. Absorbance at 280 nm is frequently used to measure Aβ concentration, but the sensitivity is low with only one tyrosine and no tryptophan residues in the Aβ sequence. Here we present a fluorescence method for Aβ quantification using fluorescamine, which gives high fluorescence upon reaction with primary amines. We show that, using hen egg white lysozyme as a standard, fluorescence correlates linearly with primary amine concentration across a wide range of fluorescamine concentrations, from 62.5 to 1000 µM. The maximal sensitivity of detection is achieved at a fluorescamine concentration of 250 µM or higher. The fluorescamine method is compatible with the presence of dimethyl sulfoxide, which is commonly used in the preparation of Aβ oligomers, and limits the use of absorbance at 280 nm due to its high background reading. Using aggregation kinetics, we show that the fluorescamine method gives accurate concentration measurements at low micromolar range and leads to highly consistent aggregation data. We recommend the fluorescamine assay to be used for routine and on-the-fly concentration determination in Aβ oligomerization and fibrillization experiments.
Human altruism, evolution and moral philosophy
Authors: FitzPatrick William J.
Published: August 2017

This paper has two central aims. The first is to explore philosophical complications that arise when we move from (i) explaining the evolutionary origins of genetically influenced traits associated with human cooperation and altruism, to (ii) explaining present manifestations of human thought, feeling and behaviour involving cooperation and altruism. While the former need only appeal to causal factors accessible to scientific inquiry, the latter must engage also with a distinctive form of explanation, i.e. reason-giving explanation, which in turn raises important philosophical questions, the answers to which will affect the nature of the ultimate explanations of our moral beliefs and related actions. On one possibility I will explore, this explanatory project cannot avoid engaging with first-order ethical theory. The second aim is to apply lessons from these explanatory complications to the critique of ‘evolutionary debunking arguments’, which seek to debunk morality, or at least objective construals of it (i.e. moral realism), by appeal to allegedly scientific debunking explanations of our moral beliefs that would defeat our justification for them. The explanatory complications brought out in the first half raise difficulties for such debunking arguments. If we avoid begging central philosophical questions then such debunking arguments pose little threat of saddling us with moral scepticism or subjectivism, though they do pose an important challenge for those developing a moral realist view.
Pollination benefits are maximized at intermediate nutrient levels
Authors: Tamburini Giovanni , Lami Francesco , Marini Lorenzo
Published: August 2017

Yield production in flowering crops depends on both nutrient availability and pollination, but their relative roles and potential interactions are poorly understood. We measured pollination benefits to yield in sunflower, combining a gradient in insect pollination (0, 25, 50, 100%) with a continuous gradient in nitrogen (N) fertilization (from 0 to 150 kg N ha−1) in an experiment under realistic soil field conditions. We found that pollination benefits to yield were maximized at intermediate levels of N availability, bolstering yield by approximately 25% compared with complete pollinator exclusion. Interestingly, we found little decrease in yield when insect visits were reduced by 50%, indicating that the incremental contribution of pollination by insects to yield is greater when the baseline pollination service provision is very low. Our findings provide strong evidence for interactive, nonlinear effects of pollination and resource availability on seed production. Our results support ecological intensification as a promising strategy for sustainable management of agroecosystems. In particular, we found optimal level of pollination to potentially compensate for lower N applications.
Revised time scales of RNA virus evolution based on spatial information
Authors: Saxenhofer Moritz , Weber de Melo Vanessa , Ulrich Rainer G. , Heckel Gerald
Published: August 2017

The time scales of pathogen evolution are of major concern in the context of public and veterinary health, epidemiology and evolutionary biology. Dating the emergence of a pathogen often relies on estimates of evolutionary rates derived from nucleotide sequence data. For many viruses, this has yielded estimates of evolutionary origins only a few hundred years in the past. Here we demonstrate through the incorporation of geographical information from virus sampling that evolutionary age estimates of two European hantaviruses are severely underestimated because of pervasive mutational saturation of nucleotide sequences. We detected very strong relationships between spatial distance and genetic divergence for both Puumala and Tula hantavirus—irrespective of whether nucleotide or derived amino acid sequences were analysed. Extrapolations from these relationships dated the emergence of these viruses most conservatively to at least 3700 and 2500 years ago, respectively. Our minimum estimates for the age of these hantaviruses are ten to a hundred times older than results from current non-spatial methods, and in much better accordance with the biogeography of these viruses and their respective hosts. Spatial information can thus provide valuable insights on the deeper time scales of pathogen evolution and improve our understanding of disease emergence.
A spatial memory signal shows that the parietal cortex has access to a craniotopic representation of space
Authors: Semework Mulugeta , Steenrod Sara C. , Goldberg Michael E.
Published: August 2017

Humans effortlessly establish a gist-like memory of their environment whenever they enter a new place. They can then use this memory to guide action even in the absence of vision. Neurons in the lateral intraparietal area (LIP) of the monkey exhibit a form of this environmental memory, responding when a monkey makes a saccade that brings the spatial location of a stimulus that appeared on a number of prior trials, but not on the present trial into their receptive fields. The stimulus need never have appeared in the receptive field of the neuron. This response is usually weaker with a longer latency than the neuron's visual response. We suggest that these results demonstrate that LIP has access to a craniotopic memory of space, which is activated when the spatial location of the vanished stimulus can be described by a retinotopic vector from the center of gaze to the stimulus.
Unexpected mixed-mode transmission and moderate genetic regulation ofSymbiodiniumcommunities in a brooding coral
Authors: Quigley Kate M. , Warner Patricia A. , Bay Line K. , Willis Bette L.
Published: August 2017

Determining the extent to whichSymbiodiniumcommunities in corals are inherited versus environmentally-acquired is fundamental to understanding coral resilience and to predicting coral responses to stressors like warming oceans that disrupt this critical endosymbiosis. We examined the fidelity with whichSymbiodiniumcommunities in the brooding coralSeriatopora hystrixare vertically transmitted and the extent to which communities are genetically regulated, by genotyping 60 larvae and their parents (9 maternal and 45 paternal colonies) using high throughput sequencing of the ITS-2 locus. Unexpectedly,Symbiodiniumcommunities associated with brooded larvae were distinct from those within parent colonies, including the presence of types not detected in adults. Bayesian heritability (h2) analysis revealed that 33% of variability in larvalSymbiodiniumcommunities was genetically controlled. Results highlight flexibility in the establishment of larval communities and overturn the paradigm that symbiont transmission is exclusively vertical in brooding corals. Instead, we show thatSymbiodiniumtransmission inS. hystrixinvolves a mixed-mode strategy, similar to many terrestrial invertebrate symbioses. Also, variation in the abundances of commonSymbiodiniumtypes among adult communities suggests that microhabitat differences influence the structure ofin hospite Symbiodiniumcommunities. Partial genetic regulation coupled with flexibility in the environmentally-acquired component of larvalSymbiodiniumcommunities implies that corals with vertical transmission, likeS. hystrix,may be more resilient to environmental change than previously thought.
SureMap: Versatile, Error Tolerant, and High Sensitive Read Mapper
Authors: Seraji MohammadJavad Rezaei , Motahari Seyed Abolfazl
Published: August 2017

SureMap is a versatile, error tolerant and high sensitive read mapper which is able to map “difficult” reads, those requiring many edit operations to be mapped to the reference genome, with acceptable time complexity. Mapping real datasets reveal that many variants unidentifiable by other mappers can be called using Suremap. Moreover SureMap has a very good running time and accuracy in aligning very long and noisy reads like PacBio and Nanopore against reference genome.
Lung tumors with distinct p53 mutations respond similarly to p53 targeted therapy but exhibit genotype-specific statin sensitivity
Authors: Turrell Frances K. , Kerr Emma M. , Gao Meiling , Thorpe Hannah , Doherty Gary J. , Cridge Jake , Shorthouse David , Speed Alyson , Samarajiwa Shamith , Hall Benjamin A. , Griffiths Meryl , Martins Carla P.
Published: August 2017

Lung adenocarcinoma accounts for ∼40% of lung cancers, the leading cause of cancer-related death worldwide, and current therapies provide only limited survival benefit. Approximately half of lung adenocarcinomas harbor mutations in TP53 (p53), making these mutants appealing targets for lung cancer therapy. As mutant p53 remains untargetable, mutant p53-dependent phenotypes represent alternative targeting opportunities, but the prevalence and therapeutic relevance of such effects (gain of function and dominant-negative activity) in lung adenocarcinoma are unclear. Through transcriptional and functional analysis of murine KrasG12D-p53null, -p53R172H (conformational), and -p53R270H (contact) mutant lung tumors, we identified genotype-independent and genotype-dependent therapeutic sensitivities. Unexpectedly, we found that wild-type p53 exerts a dominant tumor-suppressive effect on mutant tumors, as all genotypes were similarly sensitive to its restoration in vivo. These data show that the potential of p53 targeted therapies is comparable across all p53-deficient genotypes and may explain the high incidence of p53 loss of heterozygosity in mutant tumors. In contrast, mutant p53 gain of function and their associated vulnerabilities can vary according to mutation type. Notably, we identified a p53R270H-specific sensitivity to simvastatin in lung tumors, and the transcriptional signature that underlies this sensitivity was also present in human lung tumors, indicating that this therapeutic approach may be clinically relevant.
SIRT7 and the DEAD-box helicase DDX21 cooperate to resolve genomic R loops and safeguard genome stability
Authors: Song Chenlin , Hotz-Wagenblatt Agnes , Voit Renate , Grummt Ingrid
Published: August 2017

R loops are three-stranded nucleic acid structures consisting of an RNA:DNA heteroduplex and a “looped-out” nontemplate strand. As aberrant formation and persistence of R loops block transcription elongation and cause DNA damage, mechanisms that resolve R loops are essential for genome stability. Here we show that the DEAD (Asp–Glu–Ala–Asp)-box RNA helicase DDX21 efficiently unwinds R loops and that depletion of DDX21 leads to accumulation of cellular R loops and DNA damage. Significantly, the activity of DDX21 is regulated by acetylation. Acetylation by CBP inhibits DDX21 activity, while deacetylation by SIRT7 augments helicase activity and overcomes R-loop-mediated stalling of RNA polymerases. Knockdown of SIRT7 leads to the same phenotype as depletion of DDX21 (i.e., increased formation of R loops and DNA double-strand breaks), indicating that SIRT7 and DDX21 cooperate to prevent R-loop accumulation, thus safeguarding genome integrity. Moreover, DDX21 resolves estrogen-induced R loops on estrogen-responsive genes in breast cancer cells, which prevents the blocking of transcription elongation on these genes.
Three-dimensional texture visualization approaches: applications to nickel and titanium alloys
Authors: Callahan Patrick G. , Echlin McLean P. , Stinville Jean Charles , Pollock Tresa M. , Singh Saransh , Ram Farangis , De Graef Marc
Published: August 2017

This paper applies the three-dimensional visualization techniques explored theoretically by Callahan, Echlin, Pollock, Singh & De Graef [J. Appl. Cryst.(2017),50, 430–440] to a series of experimentally acquired texture data sets, namely a sharp cube texture in a single-crystal Ni-based superalloy, a sharp Goss texture in single-crystal Nb, a random texture in a powder metallurgy polycrystalline René 88-DT alloy and a rolled plate texture in Ti-6Al-4V. Three-dimensional visualizations are shown (and made available as movies as supplementary material) using the Rodrigues, Euler and three-dimensional stereographic projection representations. In addition, it is shown that the true symmetry of Euler space, as derived from a mapping onto quaternion space, is described by the monoclinic color space groupPccin the Opechowski and Guccione nomenclature.
Characterization of individual stacking faults in a wurtzite GaAs nanowire by nanobeam X-ray diffraction
Authors: Davtyan Arman , Lehmann Sebastian , Kriegner Dominik , Zamani Reza R. , Dick Kimberly A. , Bahrami Danial , Al-Hassan Ali , Leake Steven J. , Pietsch Ullrich , Holý Václav
Published: August 2017

Coherent X-ray diffraction was used to measure the type, quantity and the relative distances between stacking faults along the growth direction of two individual wurtzite GaAs nanowires grown by metalorganic vapour epitaxy. The presented approach is based on the general property of the Patterson function, which is the autocorrelation of the electron density as well as the Fourier transformation of the diffracted intensity distribution of an object. Partial Patterson functions were extracted from the diffracted intensity measured along the [000\bar{1}] direction in the vicinity of the wurtzite 00\bar{1}\bar{5} Bragg peak. The maxima of the Patterson function encode both the distances between the fault planes and the type of the fault planes with the sensitivity of a single atomic bilayer. The positions of the fault planes are deduced from the positions and shapes of the maxima of the Patterson function and they are in excellent agreement with the positions found with transmission electron microscopy of the same nanowire.
Unlocking hospitality managers career transitions through applying Schein’s career anchors theory
Authors: McGuire David , Polla Giovana , Heidl Britta
Published: August 2017

Purpose

This paper seeks to unlock the career transitions of hospitality managers through applying Schein’s career anchors theory. It seeks to understand how Schein’s Career Anchors help explain the career transitions of managers in the Scottish hospitality industry.

Design/methodology/approach

The paper adopts a non-sequential multi-method design. All 22 hospitality managers who participated in the study completed an online version of Schein’s Career Anchors containing 40 items covering all eight career anchors. The career histories of participants were then gathered through use of a semi-structured interview. Comparisons were then drawn across the career anchor classification and the data on career transitions collected from participants.

Findings

The results highlight the continued relevance of Schein’s career anchors theory and indicate that Schein’s career anchors theory may constitute a useful tool for understanding hospitality managers’ career needs and engaging in meaningful career planning.

Originality/value

The study provides a useful insight into hospitality managers’ career motivations, and knowledge of career anchors will help hospitality organisations more effectively engage, recruit and retain hospitality managers.
US REITs capital structure determinants and financial economic crisis effects
Authors: Morri Giacomo , Parri Edoardo
Published: August 2017

Purpose

The purpose of this paper is to identify the capital structure determinants through an analysis of 74 All-Equity REITs listed in the US market from 2005 to 2014. Furthermore, the paper aims at understanding the impact of the financial economic crisis (FEC) among the identified explanatory variables.

Design/methodology/approach

A fixed effect panel regression model is performed based on Trade-off Theory (TOT) and Pecking Order Theory as a starting point to provide expectations on the relationships incurring among the identified variables.

Findings

First, while tangibility of assets and crisis evidenced a positive relationship with REITs’ financial leverage, operating risk and growth opportunities variables displayed a negative relationship. Meanwhile, size and profitability did not appear to influence the capital structure. Second, it appears that the positive effects of tangibility of assets and profitability variables on US REITs’ capital structure increased as a consequence of the FEC. Operating risk and growth opportunities variables slightly increased their negative relationship with US REITs’ capital structure after the FEC. The TOT prevails when explaining the economic reality underlying US REITs.

Practical implications

The paper contributes to the understanding of US REITs’ financing decisions within the US market. The FEC also had a substantial indirect impact on the financial leverage determinants of US REITs, the latter being nowadays more oriented to maintaining a flexible capital structure.

Originality/value

The paper provides a comprehensive view of the medium-term effect of the FEC on US REITs’ capital structure.
Synthesis and evaluation of novel antibacterial monoazo disperse dyes based on sulfonamide derivatives on polyester
Authors: Mokhtari Javad , Babaii Bahareh , Akbarzadeh Abolfath , Ferdowsi Parnian
Published: August 2017

Purpose

This paper aims to present the design and synthesis of a series of novel antibacterial monoazo disperse dyes based on sulfonamide derivatives to combine the dyeing and functional finishing steps on polyester into one process.

Design/methodology/approach

The diazoniom salts of sulfonamides, namely, 4-amino-N-(2-pyrimidinyl) benzenesulfonamide, 4-amino-N-(4-methyl-2-pyrimidinyl) benzenesulfonamide and 4-amino-N-(4,6-dimethyl-2-pyrimidinyl) benzenesulfonamide were prepared and then coupled to N,N-diethyl aniline, N,N-dicyanoethyl aniline and N,N-dihydroxy ethyl aniline, respectively, to produce the dyes.

Findings

The structures of the dyes were characterized using their spectral data (FTIR, 1H-NMR, UV-Vis) and elemental analysis. The results indicated that all the dyes exhibit positive solvatochromism in more polar solvents. Dispersion of the dyes was prepared in water and applied to polyester fabrics. The synthesized dye 3a which had good exhaustion on the fabric (89.98 per cent) and were tinctorially stronger (28899 l/mol.cm) showed higher visual colour yield (16.51). The antibacterial efficacy of the dyes was assessed, and they showed activity against both gram-positive and gram-negative bacteria but in different levels depending on their structures.

Research limitations/implications

A simple way to combing functional finishing and dyeing in one process was successfully performed via design and synthesis of disperse dyes with an antibacterial moiety incorporated into dye molecules. The dyes were fully charaterized and evaluated on polyester.

Originality/value

A series of novel antibacterial monoazo disperse dyes based on sulfonamide derivatives were synthesized. The authors studied their application for dyeing of polyester fabric. The dyes offered good results in terms of preparation, yield, purity, visual colour yield, fastness properties and activity against bacteria.
Synthesis of novel dyes based on curcumin for the creation of antibacterial silk fabrics
Authors: Gaffer Hatem , Mashaly Hamada , Abdel-Rhman Shaymaa Hassan , Hammouda Mamdouh
Published: August 2017

Purpose

The study reported in this paper aims to synthesize some new curcumin containing sulphadiazine and sulphathiazole dyestuffs and study their application in dyeing silk fabrics rendering the dyed fabric antibacterial.

Design/methodology/approach

Simultaneous dyeing and antibacterial finishing for silk fabric using a new antibacterial acid dye having a modified chemical structure to curcumin were conducted. This modification of curcumin dye was carried out by introducing sulphonamide containing heterocyclic rings sulphadiazine and sulfathiazole through coupling with curcumin. All newly synthesized dyes were characterized by elemental analyses and spectral data (IR, 1H-NMR and MS). The dyeing characteristics of these dyestuffs were evaluated at optimum conditions. Antibacterial activities of the dyed samples at different concentrations of both dyes were studied against gram-positive (Staphylococcus aureus) and gram-negative (Salmonella typhimurium) bacteria.

Findings

The synthesized curcumin-containing sulphonamide dyes were applied on silk fabrics. The modified dyes exhibited good fastness properties compared to curcumin dye at optimum conditions. It was found that synthesized dyes exhibit good fastness and antibacterial properties efficient against gram-positive and gram-negative bacteria. The dyed silk fabrics showed higher antibacterial efficacy after many times of washing.

Originality/value

Curcumin, a common natural dye used for fabric and food colouration, was used as an antimicrobial finish due to its bactericidal properties on dyed textiles. A common dyeing process could provide textiles with colour as well as antimicrobial properties. Novel antibacterial dyestuff containing curcumin moieties with sulphonamide coupler components were shown to be an interesting natural colorant for silk with high antimicrobial ability of the dyed silk fabrics. This work has afforded a new acid dye that can be used in medical textile.
Physico-chemical characterisation of epoxy acrylate resin from jatropha seed oil
Authors: Jusoh Taib Emiliana Rose , Abdullah Luqman Chuah , Aung Min Min , Basri Mahiran , Salleh Mek Zah , Saalah Sariah , Mamat Suhaini , Chee Ching Yern , Wong Jia Li
Published: August 2017

Purpose

This paper aims to demonstrate the synthesis of polyesterification reaction of non-edible jatropha seed oil (JO) and acrylic acid, which leads to the production of acrylated epoxidised-based resin. To understand the physico-chemical characteristics when synthesis the JO-based epoxy acrylate, the effect of temperature on the reaction, concentration of acrylic acid and role of catalyst on reaction time and acid value were studied.

Design/methodology/approach

First, the double bond in JO was functionalised by epoxidation using the solvent-free performic method. The subsequent process was acrylation with acrylic acid using the base catalyst triethylamine and 4-methoxyphenol as an inhibitor respectively. The physico-chemical characteristics during the synthesis of the epoxy acrylate such as acid value was monitored and analysed. The formation of the epoxy and acrylate group was confirmed by a Fourier transform infrared spectroscopy spectra analysis and nuclear magnetic resonance analysis.

Findings

The optimum reaction condition was achieved at a ratio of epoxidised JO to acrylic acid of 1:1.5 and the reaction temperature of 110°C. This was indicated by the acid value reduction from 86 to 15 mg KOH/g sample at 6 hours.

Practical implications

The JO-based epoxy acrylate synthesised has a potential to be used in formulations the prepolymer resin for UV curable coating applications. The JO which is from natural resources and is sustainable raw materials that possible reduce the dependency on petroleum-based coating.

Originality/value

The epoxidised jatropha seed oil epoxy acrylate was synthesised, as a new type of oligomer resin that contains a reactive acrylate group, which can be alternative to petroleum-based coating and can used further in the formulation of the radiation curable coating.
Exploring the feasibility of a classroom‐based vocabulary intervention for mainstream secondary school students with language disorder
Authors: Lowe Hilary , Joffe Victoria
Published: August 2017

Vocabulary knowledge has been shown to be a predictor of academic success, posing a challenge for children and young people with language disorder. Language disorder can persist into adolescence and yet there is limited evidence on how to support the vocabulary skills of adolescents with language disorder in a mainstream setting. This article describes an experimental study aimed at investigating the feasibility of a whole‐class approach to increase the understanding and use of curriculum vocabulary in adolescents with language disorder. Ten curriculum words were taught by the science teacher using a phonological‐semantic approach, and 10 matched same‐topic words were taught using routine teaching practice. Progress was made post‐intervention in word knowledge of both low‐frequency experimental and control words, with significantly greater change in knowledge of the experimental words. Most students, and the teacher, viewed the phonological‐semantic word‐learning approach favourably.
Improving the resilience of disaster management organizations through virtual communities of practice: A Delphi study
Authors: Gimenez Raquel , Hernantes Josune , Labaka Leire , Hiltz Starr Roxanne , Turoff Murray
Published: August 2017

A resilience‐focused approach leads organizations to improve the management of disasters through being aware, flexible, trained, and prepared, having committed top managers and staff, and being part of a wider network of stakeholders. Based on the organizational resilience principles identified in the literature, this article analyses the potential for improvement of the organizational resilience of disaster management organizations through their involvement in virtual communities of practice (VCoPs). VCoPs are groups of stakeholders from different organizations with a common interest that collaborate and exchange knowledge on a regular basis. This article presents a Delphi study that was conducted with a multidisciplinary group of international experts that work in disaster management organizations to evaluate the contribution of VCoPs. The results of the Delphi show that VCoPs help organizations to improve the organizational resilience principles. Nevertheless, there is still a series of barriers that organizations need to face in terms of collaboration and information sharing. This article classifies the existing barriers that hinder participation in VCoPs and suggests solutions to overcome them.
Resilience, culture change, and cancer risk reduction in a fire rescue organization: Clean gear as the new badge of honor
Authors: Harrison Tyler R. , Yang Fan , Anderson David , Morgan Susan E. , Wendorf Muhamad Jessica , Talavera Ed , Schaefer Solle Natasha , Lee David , Caban‐Martinez Alberto J. , Kobetz Erin
Published: August 2017

Fire rescue organizations are central to community models of resilience, especially in the context of crisis. The ability of fire rescue organizations to fulfill their role relies on their ability to operate at full capacity; however, fire rescue services may face internal crises that require these organizations to be resilient in their own right. This study uses grounded theory drawing on concepts of organizational culture and resilience to show how one key partner in the community model of resilience (Palm Beach County Fire Rescue) is working to address their own crisis—an epidemic of cancer. Firefighters are engaging in behaviours to increase resilience by working towards cultural change to reduce cancer risk, using social capital to increase networks and expertise, and utilizing internal assets to enact change. Barriers to change include cultural practices, perceived threats to occupational practice, and logistics and resources to enact desired change. A model of risk reduction and resilience is advanced that explores how organizational culture and practice both support and undermine individual resilience and organizational resilience. Implications for communication and change efforts are explored.