bluuebunny/crossref_metadata_2025 huggingface dataset:
Mathematical Modeling of Nylon 6/6,6 Copolymerization: Beneficial Influence of Comonomers on Degree of Polymerization in Batch Reactor
Authors: Liu Fei F. , Hurley James M. , Khare Neeraj P. , McAuley Kim B.
Published: May 2017

A model is developed for hydrolytic copolymerization of caprolactam with hexamethylene diamine (HMD) and adipic acid (ADA) in a batch reactor to produce nylon 6/6,6 copolymer. The reaction mechanism includes hydrolysis of caprolactam and cyclic dimer, polycondensation, polyaddition, transamidation, and ring formation via end biting and back biting. The catalyzing effect of carboxyl groups is accounted for using kinetic parameters from the literature. Model predictions are compared with low‐temperature literature data before simulating reactor conditions of industrial interest. The model predicts a higher degree of polymerization (DP) for nylon 6/6,6 copolymer compared to nylon 6 and 6,6 homopolymers produced using the same reactor conditions. Dynamic changes in concentrations of water, caprolactam, HMD, ADA, and end groups are tracked and used to explain the positive influence of comonomers on reaction rates and DP. Insights gained from this model will form a useful basis to build future models of continuous industrial reactors.

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The surface modification by carboxyl ionic liquid for mesoporous silica and the preparation of composite polymer electrolyte with the modified mesoporous silica
Authors: Lu Yanbo , Wang Ran , Ren Wentan , Zhang Yong
Published: May 2017

A modified mesoporous silica was prepared by esterification reaction of the hydroxyl group on the surface of mesoporous silica with 1‐carboxymethyl‐3‐methyl imidazolium bis(trifluoromethylsulfonate)imine ([(HOOC)C1C1Im][NTf2]). The esterification reaction and structure of the modified mesoporous silica were investigated using the X‐ray photoelectron spectroscopy, Nitrogen adsorption–desorption analysis, Transmission electronic microscopy, Field emission scanning electronic microscopy, Energy dispersive X‐ray spectroscopy, and Thermogravimetric analysis.The analysis results indicated that the carboxyl group of [(HOOC) C1C1Im] [NTf2] can occur the catalytic esterification reaction with the hydroxyl group on the surface of mesoporous silica and the introduction of ILs did not affect the long range ordered pore structure of mesoporous silica, and the modified mesoporous silica contains 8.14% (wt.) of [(HOOC)C1C1Im][NTf2]. In addition, a composite polymer electrolyte (CPE) was prepared through introducing the modified mesoporous silica and bis (trifluoromethanesulfon) imide lithium salt (LiTFSI) into the carboxylate butadiene‐acrylonitrile rubber (XNBR) matrix and the ionic conductivity and mechanical properties of the CPE were studied. The results showed that the mechanical properties and ionic conductivity of the CPE were obviously improved by filling the modified mesoporous silica. When loading 20 phr modified mesoporous silica, the tensile strength was increased to 6.2 MPa from 2.4 MPa, and that the ionic conductivity at room temperature was increased to 1.5 × 10−5 S/cm from 2.0 × 10−6 S/cm. POLYM. COMPOS., 39:3586–3593, 2018. © 2017 Society of Plastics Engineers
Human Neural Stem Cell Biodistribution and Predicted Tumor Coverage by a Diffusible Therapeutic in a Mouse Glioma Model
Authors: Barish Michael E. , Herrmann Kelsey , Tang Yang , Argalian Herculian Siranush , Metz Marianne , Aramburo Soraya , Tirughana Revathiswari , Gutova Margarita , Annala Alexander , Moats Rex A. , Goldstein Leanne , Rockne Russell C. , Gutierrez Jennifer , Brown Christine E. , Ghoda Lucy , Aboody Karen S.
Published: May 2017

Engineered neural stem cells (NSCs) intrinsically migrating to brain tumors offer a promising mechanism for local therapeutic delivery. However, difficulties in quantitative assessments of NSC migration and in estimates of tumor coverage by diffusible therapeutics have impeded development and refinement of NSC-based therapies. To address this need, we developed techniques by which conventional serial-sectioned formalin-fixed paraffin-embedded (FFPE) brains can be analyzed in their entirety across multiple test animals. We considered a conventional human glioblastoma model: U251 glioma cells orthotopically engrafted in immunodeficient mice receiving intracerebral (i.c.) or intravenous (i.v.) administrations of NSCs expressing a diffusible enzyme to locally catalyze chemotherapeutic formation. NSC migration to tumor sites was dose-dependent, reaching 50%–60% of total administered NSCs for the i.c route and 1.5% for the i.v. route. Curiously, the most efficient NSC homing was seen with smaller NSC doses, implying existence of rate-limiting process active during administration and/or migration. Predicted tumor exposure to a diffusing therapeutic (assuming a 50 µm radius of action) could reach greater than 50% of the entire tumor volume for i.c. and 25% for i.v. administration. Within individual sections, coverage of tumor area could be as high as 100% for i.c. and 70% for i.v. routes. Greater estimated therapeutic coverage was observed for larger tumors and for larger tumor regions in individual sections. Overall, we have demonstrated a framework within which investigators may rationally evaluate NSC migration to, and integration into, brain tumors, and therefore enhance understanding of mechanisms that both promote and limit this therapeutic modality.
A Perylenediimide Tetramer‐Based 3D Electron Transport Material for Efficient Planar Perovskite Solar Cell
Authors: Cheng Ming , Li Yuanyuan , Liu Peng , Zhang Fuguo , Hajian Alireza , Wang Haoxin , Li Jiajia , Wang Linqin , Kloo Lars , Yang Xichuan , Sun Licheng
Published: May 2017

A perylenediimide (PDI) tetramer‐based three dimensional (3D) molecular material, termed SFX‐PDI4, has been designed, synthesized, and characterized. The low‐lying HOMO and LUMO energy levels, high electron mobility and good film‐formation property make it a promising electron transport material (ETM) in inverted planar perovskite solar cells (PSCs). The device exhibits a high power conversion efficiency (PCE) of 15.3% with negligible hysteresis, which can rival that of device based on PC61BM. These results demonstrate that three dimensional PDI‐based molecular materials could serve as high performance ETMs in PSCs.
Long-Range Dependence and Self-Similarity
Authors: Pipiras Vladas , Taqqu Murad S.
Published: May 2017

This modern and comprehensive guide to long-range dependence and self-similarity starts with rigorous coverage of the basics, then moves on to cover more specialized, up-to-date topics central to current research. These topics concern, but are not limited to, physical models that give rise to long-range dependence and self-similarity; central and non-central limit theorems for long-range dependent series, and the limiting Hermite processes; fractional Brownian motion and its stochastic calculus; several celebrated decompositions of fractional Brownian motion; multidimensional models for long-range dependence and self-similarity; and maximum likelihood estimation methods for long-range dependent time series. Designed for graduate students and researchers, each chapter of the book is supplemented by numerous exercises, some designed to test the reader's understanding, while others invite the reader to consider some of the open research problems in the field today.
Decolonization in a Digital Age: Cryptocurrencies and Indigenous Self-Determination in Canada
Authors: Alcantara Christopher , Dick Caroline
Published: May 2017

Indigenous scholars and leaders have long been interested in reducing the role of the Canadian state in their political, economic, and social lives. This paper explores the extent to which digital currencies, such as Bitcoin or MazaCoin, might be used to facilitate Indigenous self-determination, political autonomy, and economic prosperity. Based on our review of the literature, we argue that cryptocurrencies demonstrate some potential for advancing these goals but that there are a number of potential roadblocks as well. Future research should investigate how Indigenous communities might use digital currencies and other related technologies to further their political, economic, and social goals.
Ngoelmun Yawar, Our Journey: The Transition and the Challenges for Female Students Leaving Torres Strait Island Communities for Boarding Schools in Regional Queensland
Authors: Bobongie Francis
Published: May 2017

This paper explores the transitional experiences and challenges faced by girls from the Torres Strait Islands when they leave individual communities to attend boarding school in regional Queensland. The paper presents original ethnographic research using a narrative enquiry approach, capturing stories as narrated by a broad cohort of girls from within these communities, both past and present students. The stories relayed in this article are integral to assisting parents and extended family, staff and administrators to better manage the transition process from one community to another. Identifying the cultural, social and academic challenges associated with the transition process will enable those involved in student support both within the community and the school system to do so with an enhanced awareness so that the students involved may be helped to negotiate this experience more easily. This paper will also inform, although not directly engaging with the topic, the ongoing debate about the advantages and disadvantages of girls leaving their communities to attend boarding school. It will also add weight to the call to improve current strategies to assist with the transition process.
Automating long-term glacier dynamics monitoring using single-station seismological observations and fuzzy logic classification: a case study from Spitsbergen
Authors: GAJEK W. , TROJANOWSKI J. , MALINOWSKI M.
Published: May 2017

Retreating glaciers are a consequence of a warming climate. Thus, numerous monitoring campaigns are being carried out to increase understanding of this on-going process. One phenomenon related to dynamic glacial changes is glacier-induced seismicity; however, weak seismic events are difficult to record due to the sparse seismological network in arctic areas. We have developed an automatic procedure capable of detecting glacier-induced seismic events using records from a single permanent seismological station. To distinguish between glacial and non-glacial signals, we developed a fuzzy logic algorithm based on the signal frequency and energy flow analysis. We studied the long-term changes in glacier-induced seismicity in Hornsund (southern Spitsbergen) and in Kongsfjorden (western Spitsbergen). We found that the number of detected glacial-origin events in the Hornsund dataset over the years 2013-14 has doubled. In the Kongsfjorden dataset, we observed a steady increase in the number of glacier-induced events with each year. We also observed that the seasonal event distribution correlates best with 1 month lagged temperatures, and that extreme rain events can intensify seismic emissions. Our study demonstrates the possibility of using long-term seismological observations from a single permanent station to automatically monitor the dynamic activity of nearby glaciers and retrieve its characteristic features.
Alcohol consumption pattern and risk of Barrett’s oesophagus and erosive oesophagitis: an Italian case–control study
Authors: Filiberti Rosa A. , Fontana Vincenzo , De Ceglie Antonella , Blanchi Sabrina , Grossi Enzo , Della Casa Domenico , Lacchin Teresa , De Matthaeis Marina , Ignomirelli Orazio , Cappiello Roberta , Rosa Alessandra , Foti Monica , Laterza Francesco , D’Onofrio Vittorio , Iaquinto Gaetano , Conio Massimo
Published: May 2017

Knowledge about the association between alcohol and Barrett’s oesophagus and reflux oesophagitis is conflicting. In this case–control study we evaluated the role of specific alcoholic beverages (red and white wine, beer and liquors) in 339 Barrett’s oesophagus and 462 oesophagitis patients compared with 619 endoscopic controls with other disorders, recruited in twelve Italian endoscopic units. Data on alcohol and other individual characteristics were obtained from structured questionnaires. No clear, monotonic significant dose–response relationship was pointed out for red wine. However, a generalised U-shaped trend of Barrett’s oesophagus/oesophagitis risk due to red wine consumption particularly among current drinkers was found. Similar results were also found for white wine. Liquor/spirit consumption seemed to bring about a 1·14–2·30 risk excess, although statistically non-significant, for current Barrett’s oesophagus/oesophagitis drinkers. Statistically significant decreasing dose–response relationships were found in Barrett’s oesophagus for frequency and duration of beer consumption. Similar, but less clear downward tendencies were also found for oesophagitis patients. In conclusion, although often not statistically significant, our data suggested a reduced risk of Barrett’s oesophagus and oesophagitis with a low/moderate intake of wine and beer consumption. A non-significant increased risk of Barrett’s oesophagus/oesophagitis was observed with a higher intake of any type of heavy alcohol consumption, but no conclusion can be drawn owing to the high number of non-spirit drinkers and to the small number of drinkers at higher alcohol intake levels.
Implications of Genetically Modified Crops and Intellectual Property Rights on Agriculture in Developing Countries
Authors: Olusegun Olaitan Oluwaseyi , Olubiyi Ifeoluwa Ayokunle
Published: May 2017

Food is essential for human survival. When the right quantity and quality is taken, it ensures growth and an adequate supply of nutrition to the body, which results in basic effectiveness in all spheres of life. Genetically modified crops have the potential to alleviate hunger and provide more food, especially in developing countries that have high levels of hunger, malnutrition and poverty. Although the debates on genetically modified crops generally focus on intellectual property, other issues include health and environmental concerns. This article examines these issues with the aim of providing holistic knowledge of the subject matter, which is important for stakeholders, particularly in developing countries, in deciding to protect plant variety rights. The article concludes that it is essential for developing countries to consider food security issues in fulfilling their obligations under the TRIPS Agreement.
New Evidence on Mutual Fund Performance: A Comparison of Alternative Bootstrap Methods
Authors: Blake David , Caulfield Tristan , Ioannidis Christos , Tonks Ian
Published: May 2017

We compare two bootstrap methods for assessing mutual fund performance. The first produces narrow confidence intervals due to pooling over time, whereas the second produces wider confidence intervals because it preserves the cross correlation of fund returns. We then show that the average U.K. equity mutual fund manager is unable to deliver outperformance net of fees under either bootstrap. Gross of fees, 95% of fund managers on the basis of the first bootstrap and all fund managers on the basis of the second bootstrap fail to outperform the luck distribution of gross returns.
Legacies of ‘madiro’? Worker-peasantry, livelihood crisis and ‘siziphile’ land occupations in semi-arid north-western Zimbabwe
Authors: Thebe Vusilizwe
Published: May 2017

This paper examines acts of land ‘self-provisioning’ (‘siziphile’ land occupations) and ‘radical land restitution’ (of land previously annexed from people by the local authority for a pilot grazing project) by villagers in a communal area in Lupane District in north-western Zimbabwe. Situating these occurrences within the wider and historical context of ‘madiro’ (freedom farming and unauthorised development of settlements) and Matabeleland land politics and semi-proletarianisation, it stresses the livelihood history of households, the disappointments with local job opportunities and destruction of urban-based livelihoods in a crumbling economy, and the accompanying crisis of communal area agriculture. It concludes that these factors provided a real threat to semi-proletarianisation. By self-provisioning of the land the overriding concern of villagers was to maintain a certain level of livelihood survival, even if it was at odds with their livelihood strategies, while they sought opportunities to maintain semi-proletarianisation.
‘Written in Bone’: New Discoveries about the Lives and Burials of Four Roman Londoners
Authors: Redfern Rebecca C. , Marshall Michael , Eaton Katherine , Poinar Hendrik N.
Published: May 2017

The Museum of London selected four individuals for multidisciplinary scientific analyses in order to establish their ancestry, aspects of their personal appearance and health. We also reinterpreted their burial context in order to better understand how identity was constructed and expressed in this unique Roman settlement. Our study discovered the presence of people with Black and White European ancestry, some of whom had migrated from the southern Mediterranean. The most surprising result was that Harper Road woman's chromosomes were male. Overall, our experience of undertaking a multidisciplinary study served to further underline the need for these different techniques to be used in combination when investigating past identities. The mtDNA results were very broad and required the mobility isotopes to better understand their significance, while the aDNA evidence confirmed the osteological analysis. In terms of public engagement at the Museum of London, the ability to determine hair and eye colour had a significant impact.
Salt of the Hearth: Understanding the Briquetage from a Later Romano-British Saltern at Pyde Drove, near Woolavington, Somerset
Authors: Hughes Simon , Payne Naomi , Rainbird Paul
Published: May 2017

A saltern associated with salt production was excavated at Pyde Drove, near Woolavington. The large assemblage of briquetage recovered has allowed for some novel interpretations of the function of the different component types within the hearth structures. The saltern comprised a mound of waste material adjacent to 12 brine-settling tank pits and two salt water channels. A further settling tank was revealed beneath the mound. The pottery indicates that activity on the site dates to the later Romano-British period.
Mapping ‘Militant Democracy’: Variation in Party Ban Practices in European Democracies (1945-2015)
Authors: Bourne Angela K. , Casal Bértoa Fernando
Published: May 2017

Introduction – Explaining party bans, political and legal contexts – Banned parties and banning states in Europe, the political context – Nature of banned parties – Nature of banning states – Tolerant and intolerant democracies, the legal context – Evolving rationales for party bans and procedures for proscription – Contemporary rationales for banning parties – Anti-democratic ideology – Non-democratic internal organisation – Party names – Party orientation to violence – Protecting the present order – Evolving rationales for party bans – Weimar and legitimacy paradigms – Conclusions, directions for future research
A THREE-VALUED QUANTIFIED ARGUMENT CALCULUS: DOMAIN-FREE MODEL-THEORY, COMPLETENESS, AND EMBEDDING OF FOL
Authors: LANZET RAN
Published: May 2017

This paper presents an extended version of the Quantified Argument Calculus (Quarc). Quarc is a logic comparable to the first-order predicate calculus. It employs several nonstandard syntactic and semantic devices, which bring it closer to natural language in several respects. Most notably, quantifiers in this logic are attached to one-place predicates; the resulting quantified constructions are then allowed to occupy the argument places of predicates. The version presented here is capable of straightforwardly translating natural-language sentences involving defining clauses. A three-valued, model-theoretic semantics for Quarc is presented. Interpretations in this semantics are not equipped with domains of quantification: they are just interpretation functions. This reflects the analysis of natural-language quantification on which Quarc is based. A proof system is presented, and a completeness result is obtained. The logic presented here is capable of straightforward translation of the classical first-order predicate calculus, the translation preserving truth values as well as entailment. The first-order predicate calculus and its devices of quantification can be seen as resulting from Quarc on certain semantic and syntactic restrictions, akin to simplifying assumptions. An analogous, straightforward translation of Quarc into the first-order predicate calculus is impossible.
Explaining Differing Democratic Norm Commitment: Rethinking the Religion-Psychological Security-Democratic Norm Support Connection
Authors: Eisenstein Marie A. , Clark April K.
Published: May 2017

The psychological security index is an important predictor of democratic norm support. However, insufficient attention has been paid to the separate but independent contributions of dogmatism, self-esteem, and trust, the three components typically combined to create that index. Thus, we do not know the unique influence of these components on democratic norm commitment. We also do not know the exact nature of the influence of the multiple dimensions of religion (belief, belonging, behavior) on the separate psychological security components. Using structural equation modeling and two national surveys, we examine the religion-psychological security-democratic norm support relationship. Our findings do not fully support a negative association between religion and democratic values. In fact, no matter the influence of religious belief, belonging, or behavior on psychological security, the mediating link of psychological security to democratic norm support is what is most important. Indeed, any differences that manifest as a consequence of the various dimensions of religion disappear in the religion-psychological security-democratic norm support linkage. As such, anti-democratic values are a product of one's psychological attributes and are almost entirely unrelated to one's religion. Further, our findings challenge the theoretical underpinnings of the psychological security index, as we find little evidence that the separate components used to construct the composite measure, particularly trust, are an appropriate proxy for authoritarianism.
On Aërial Navigation
Authors: Cayley George
Published: May 2017

Since the days of Bishop Wilkins the scheme of flying by artificial wings has been much ridiculed, and indeed the idea of attaching wings to the arms of a man is ridiculous enough, as the pectoral muscles of a bird occupy more than two-thirds of its whole muscular strength, whereas in man the muscles that could operate upon the. wings thus attached would probably not exceed one-tenth of the whole mass. There is no proof that, weight for weight, a man is comparatively weaker than a bird; it is therefore probable, if he can be made to exert his whole strength advantageously upon a light surface similarly proportioned to his weight, as that of the wing to the bird, that he would fly like a bird. The flight of a strong man by great muscular exertion, though a curious and interesting circumstance, inasmuch as it will probably be the first means of ascertaining this power and supplying the basis whereon to improve, it would be of little use.
“Artificial Flight Attainable”
Authors: Hollands Sydney W.
Published: May 2017

It is now generally admitted that the balloon as a means of transit from place to place is essentially uncontrollable, and this remark applies in an almost equal degree to buoyant gas bags of whatever form. The main reason of this is obvious, viz., that, as regards horizontal, or even oblique progression, it is due to the great bulk offered to the wind (so much sail surface really), with which the vehicle must drift helplessly. This inevitable drifting no motor nor mechanism that the balloon will lift can counteract or cope with.
An Evaluation of Pre-emergence Metam-Potassium and S-metolachlor for Yellow Nutsedge (Cyperus esculentus) Management in Sweetpotato
Authors: Meyers Stephen L. , Shankle Mark W.
Published: May 2017

Field studies were conducted in 2014 and 2015 at Pontotoc, MS to evaluate combinations of metam-potassium and S-metolachlor for yellow nutsedge control and sweetpotato crop response. Treatments consisted of a factorial of five metam-potassium rates (0, 149, 261, 372, and 484 kgha−1) by three S-metolachlor rates (0, 0.80, and 1.34 kgha−1). Additionally, a hand-weeded check was included for comparison. Crop injury was limited to ≤4% at 4 weeks after transplanting (WAP) and was transient. At 2 WAP yellow nutsedge control was 58, 74, and 76% in plots treated with S-metolachlor at 0, 0.80, and 1.34 kgha−1, respectively. Nutsedge control in all treatments decreased from 2 to 15 WAP. At 15 WAP, S-metolachlor at 0, 0.80, and 1.34 kg ha−1 provided 35, 68, and 70% yellow nutsedge control, respectively. Metam-potassium rate did not influence yellow nutsedge control after transplanting. Sweetpotato yields in the hand-weeded check were 4,640; 22,180; 7,180; 34,000; and 1,360 kgha−1 for jumbo, no. 1, canner, marketable, and cull grades, respectively. S-metolachlor applied at either 0.80 or 1.34 kgha−1 provided jumbo, no. 1, and marketable sweetpotato yields equivalent to the hand-weeded check. Canner and cull yields were not influenced by S-metolachlor rate. Metam-potassium rates used in the present study resulted in yields equal to or greater than the hand-weeded check.
Intron retention is regulated by altered MeCP2-mediated splicing factor recruitment
Authors: Wong Justin J. -L. , Gao Dadi , Nguyen Trung V. , Kwok Chau-To , van Geldermalsen Michelle , Middleton Rob , Pinello Natalia , Thoeng Annora , Nagarajah Rajini , Holst Jeff , Ritchie William , Rasko John E. J.
Published: May 2017

While intron retention (IR) is considered a widely conserved and distinct mechanism of gene expression control, its regulation is poorly understood. Here we show that DNA methylation directly regulates IR. We also find reduced occupancy of MeCP2 near the splice junctions of retained introns, mirroring the reduced DNA methylation at these sites. Accordingly, MeCP2 depletion in tissues and cells enhances IR. By analysing the MeCP2 interactome using mass spectrometry and RNA co-precipitation, we demonstrate that decreased MeCP2 binding near splice junctions facilitates IR via reduced recruitment of splicing factors, including Tra2b, and increased RNA polymerase II stalling. These results suggest an association between IR and a slower rate of transcription elongation, which reflects inefficient splicing factor recruitment. In summary, our results reinforce the interdependency between alternative splicing involving IR and epigenetic controls of gene expression.
Quantum-circuit refrigerator
Authors: Tan Kuan Yen , Partanen Matti , Lake Russell E. , Govenius Joonas , Masuda Shumpei , Möttönen Mikko
Published: May 2017

Quantum technology promises revolutionizing applications in information processing, communications, sensing and modelling. However, efficient on-demand cooling of the functional quantum degrees of freedom remains challenging in many solid-state implementations, such as superconducting circuits. Here we demonstrate direct cooling of a superconducting resonator mode using voltage-controllable electron tunnelling in a nanoscale refrigerator. This result is revealed by a decreased electron temperature at a resonator-coupled probe resistor, even for an elevated electron temperature at the refrigerator. Our conclusions are verified by control experiments and by a good quantitative agreement between theory and experimental observations at various operation voltages and bath temperatures. In the future, we aim to remove spurious dissipation introduced by our refrigerator and to decrease the operational temperature. Such an ideal quantum-circuit refrigerator has potential applications in the initialization of quantum electric devices. In the superconducting quantum computer, for example, fast and accurate reset of the quantum memory is needed.
Highly selective covalent organic functionalization of epitaxial graphene
Authors: Bueno Rebeca A. , Martínez José I. , Luccas Roberto F. , del Árbol Nerea Ruiz , Munuera Carmen , Palacio Irene , Palomares Francisco J. , Lauwaet Koen , Thakur Sangeeta , Baranowski Jacek M. , Strupinski Wlodek , López María F. , Mompean Federico , García-Hernández Mar , Martín-Gago José A.
Published: May 2017

Graphene functionalization with organics is expected to be an important step for the development of graphene-based materials with tailored electronic properties. However, its high chemical inertness makes difficult a controlled and selective covalent functionalization, and most of the works performed up to the date report electrostatic molecular adsorption or unruly functionalization. We show hereafter a mechanism for promoting highly specific covalent bonding of any amino-terminated molecule and a description of the operating processes. We show, by different experimental techniques and theoretical methods, that the excess of charge at carbon dangling-bonds formed on single-atomic vacancies at the graphene surface induces enhanced reactivity towards a selective oxidation of the amino group and subsequent integration of the nitrogen within the graphene network. Remarkably, functionalized surfaces retain the electronic properties of pristine graphene. This study opens the door for development of graphene-based interfaces, as nano-bio-hybrid composites, fabrication of dielectrics, plasmonics or spintronics.
A general method for controlling and resolving rotational orientation of molecules in molecule-surface collisions
Authors: Godsi Oded , Corem Gefen , Alkoby Yosef , Cantin Joshua T. , Krems Roman V. , Somers Mark F. , Meyer Jörg , Kroes Geert-Jan , Maniv Tsofar , Alexandrowicz Gil
Published: May 2017

The outcome of molecule–surface collisions can be modified by pre-aligning the molecule; however, experiments accomplishing this are rare because of the difficulty of preparing molecules in aligned quantum states. Here we present a general solution to this problem based on magnetic manipulation of the rotational magnetic moment of the incident molecule. We apply the technique to the scattering of H2 from flat and stepped copper surfaces. We demonstrate control of the molecule’s initial quantum state, allowing a direct comparison of differences in the stereodynamic scattering from the two surfaces. Our results show that a stepped surface exhibits a much larger dependence of the corrugation of the interaction on the alignment of the molecule than the low-index surface. We also demonstrate an extension of the technique that transforms the set-up into an interferometer, which is sensitive to molecular quantum states both before and after the scattering event.
Inadequate sleep as a contributor to type 2 diabetes in children and adolescents
Authors: Dutil C , Chaput J-P
Published: May 2017

Lack of sleep is a modifiable risk factor for adverse health in humans. Short sleep duration and poor sleep quality are common in the pediatric population; the largest decline in sleep duration over the past decades has been seen in children and adolescents. The objective of the present narrative review was to provide for the first time an overview of the literature on sleep and its association with type 2 diabetes mellitus (T2D) biomarkers in children and adolescents. For this narrative review, 23 studies were retained (21 observational and 2 experimental studies). Notwithstanding the conflicting results found in these studies and despite being attenuated by adiposity level, maturity, sex and age, there is still some compelling evidence for an association between sleep duration (for both objective or subjective measurements of duration) and architecture with one or more T2D biomarkers in children and adolescents. The majority of the studies reviewed did focus on sleep duration and one or more T2D biomarkers in children and adolescents, but sleep architecture, more precisely the suppression of slow wave sleep and rapid eye movement sleep, has also been shown to be associated with insulin resistance. Only two studies looked at sleep quality, and the association between sleep quality and insulin resistance was not independent of level of adiposity. Future experimental studies will help to better understand the mechanisms linking insufficient sleep with T2D. Work also needs to be carried out on finding novel and effective strategies aimed at improving sleep hygiene and health outcomes of children and adolescents.
Determination of nasal and oropharyngeal microbiomes in a multicenter population-based study – findings from Pretest 1 of the German National Cohort
Authors: Akmatov Manas K. , Koch Nadine , Vital Marius , Ahrens Wolfgang , Flesch-Janys Dieter , Fricke Julia , Gatzemeier Anja , Greiser Halina , Günther Kathrin , Illig Thomas , Kaaks Rudolf , Krone Bastian , Kühn Andrea , Linseisen Jakob , Meisinger Christine , Michels Karin , Moebus Susanne , Nieters Alexandra , Obi Nadia , Schultze Anja , Six-Merker Julia , Pieper Dietmar H. , Pessler Frank
Published: May 2017

We examined acceptability, preference and feasibility of collecting nasal and oropharyngeal swabs, followed by microbiome analysis, in a population-based study with 524 participants. Anterior nasal and oropharyngeal swabs were collected by certified personnel. In addition, participants self-collected nasal swabs at home four weeks later. Four swab types were compared regarding (1) participants’ satisfaction and acceptance and (2) detection of microbial community structures based on deep sequencing of the 16 S rRNA gene V1–V2 variable regions. All swabbing methods were highly accepted. Microbial community structure analysis revealed 846 phylotypes, 46 of which were unique to oropharynx and 164 unique to nares. The calcium alginate tipped swab was found unsuitable for microbiome determinations. Among the remaining three swab types, there were no differences in oropharyngeal microbiomes detected and only marginal differences in nasal microbiomes. Microbial community structures did not differ between staff-collected and self-collected nasal swabs. These results suggest (1) that nasal and oropharyngeal swabbing are highly feasible methods for human population-based studies that include the characterization of microbial community structures in these important ecological niches, and (2) that self-collection of nasal swabs at home can be used to reduce cost and resources needed, particularly when serial measurements are to be taken.
Digital Etch Technique for Forming Ultra-Scaled Germanium-Tin (Ge
1−x
Sn
x
) Fin Structure
Authors: Wang Wei , Lei Dian , Dong Yuan , Gong Xiao , Tok Eng Soon , Yeo Yee-Chia
Published: May 2017

We developed a new digital etch process that allows precise etching of Germanium or Germanium-tin (Ge1−x
Sn
x
) materials. The digital etch approach consists of Ge1−x
Sn
x
oxide formation by plasma oxidation and oxide removal in diluted hydrochloric acid at room temperature. The first step is a self-limiting process, as the thickness of oxide layer grows logarithmically with the oxidation time and saturates fast. Consistent etch rates in each cycle were found on the Ge1−x
Sn
x
samples, with the surfaces remaining smooth after etch. The digital etch process parameters were tuned to achieve various etch rates. By reducing the radio frequency power to 70 W, etch rate of sub-1.2 nm was obtained on a Ge0.875Sn0.125 sample. The digital etch process was employed to fabricate the Ge1−x
Sn
x
fin structures. Extremely scaled Ge0.95Sn0.05 fins with 5 nm fin width were realized. The side walls of the Ge0.95Sn0.05 fins are smooth, and no crystal damage can be observed. This technique provides an option to realize aggressively scaled nanostructure devices based on Ge1−x
Sn
x
materials with high-precision control.
Quantitative trait loci for large sink capacity enhance rice grain yield under free-air CO2 enrichment conditions
Authors: Nakano Hiroshi , Yoshinaga Satoshi , Takai Toshiyuki , Arai-Sanoh Yumiko , Kondo Katsuhiko , Yamamoto Toshio , Sakai Hidemitsu , Tokida Takeshi , Usui Yasuhiro , Nakamura Hirofumi , Hasegawa Toshihiro , Kondo Motohiko
Published: May 2017

The global atmospheric CO2 concentration has been increasing annually. To determine the trait that effectively increases rice (Oryza sativa L.) grain yield under increased atmospheric CO2 concentrations, as predicted in the near future, we grew a chromosome segment substitution line (CSSL) and a near-isogenic line (NIL) producing high spikelet numbers per panicle (CSSL-GN1 and NIL-APO1, respectively) under free-air CO2 enrichment (FACE) conditions and examined the effects of a large sink capacity on grain yield, its components, and growth-related traits under increased atmospheric CO2 concentrations. Under ambient conditions, CSSL-GN1 and NIL-APO1 exhibited a similar grain yield to Koshihikari, as a result of the trade-off between increased spikelet number and reduced grain filling. However, under FACE conditions, CSSL-GN1 and NIL-APO1 had an equal or a higher grain yield than Koshihikari because of the higher number of spikelets and lower reduction in grain filling. Thus, the improvement of source activity by increased atmospheric CO2 concentrations can lead to enhanced grain yield in rice lines that have a large sink capacity. Therefore, introducing alleles that increase sink capacity into conventional varieties represents a strategy that can be used to develop high-yielding varieties under increased atmospheric CO2 concentrations, such as those predicted in the near future.
Direct Observation of Sink-Dependent Defect Evolution in Nanocrystalline Iron under Irradiation
Authors: El-Atwani O. , Nathaniel J. E. , Leff A. C. , Hattar K. , Taheri M. L.
Published: May 2017

Crystal defects generated during irradiation can result in severe changes in morphology and an overall degradation of mechanical properties in a given material. Nanomaterials have been proposed as radiation damage tolerant materials, due to the hypothesis that defect density decreases with grain size refinement due to the increase in grain boundary surface area. The lower defect density should arise from grain boundary-point defect absorption and enhancement of interstitial-vacancy annihilation. In this study, low energy helium ion irradiation on free-standing iron thin films were performed at 573 K. Interstitial loops of a
0
/2 [111] Burgers vector were directly observed as a result of the displacement damage. Loop density trends with grain size demonstrated an increase in the nanocrystalline (<100 nm) regime, but scattered behavior in the transition from the nanocrystalline to the ultra-fine regime (100–500 nm). To examine the validity of such trends, loop density and area for different grains at various irradiation doses were compared and revealed efficient defect absorption in the nanocrystalline grain size regime, but loop coalescence in the ultra-fine grain size regime. A relationship between the denuded zone formation, a measure of grain boundary absorption efficiency, grain size, grain boundary type and misorientation angle is determined.
Fitness estimates from experimental infections predict the long-term strain structure of a vector-borne pathogen in the field
Authors: Durand Jonas , Jacquet Maxime , Rais Olivier , Gern Lise , Voordouw Maarten J.
Published: May 2017

The populations of many pathogen species consist of a collection of common and rare strains but the factors underlying this strain-specific variation in frequency are often unknown. Understanding frequency variation among strains is particularly challenging for vector-borne pathogens where the strain-specific fitness depends on the performance in both the vertebrate host and the arthropod vector. Two sympatric multiple-strain tick-borne pathogens, Borrelia afzelii and B. garinii, that use the same tick vector, Ixodes ricinus, but different vertebrate hosts were studied. 454-sequencing of the polymorphic ospC gene was used to characterize the community of Borrelia strains in a local population of I. ricinus ticks over a period of 11 years. Estimates of the reproduction number (R0), a measure of fitness, were obtained for six strains of B. afzelii from a previous laboratory study. There was substantial variation in prevalence among strains and some strains were consistently common whereas other strains were consistently rare. In B. afzelii, the strain-specific estimates of R0 in laboratory mice explained over 70% of the variation in the prevalences of the strains in our local population of ticks. Our study shows that laboratory estimates of fitness can predict the community structure of multiple-strain pathogens in the field.
Visualization of a Mammalian Mitochondrion by Coherent X-ray Diffractive Imaging
Authors: Kim Yoonhee , Kim Chan , Kwon Ou Young , Nam Daewoong , Kim Sang Soo , Park Jae Hyun , Kim Sunam , Gallagher-Jones Marcus , Kohmura Yoshiki , Ishikawa Tetsuya , Song Changyong , Tae Giyoong , Noh Do Young
Published: May 2017

We report a three dimensional (3D) quantitative visualization of a mammalian mitochondrion by coherent x-ray diffractive imaging (CXDI) using synchrotron radiation. The internal structures of a mitochondrion from a mouse embryonic fibroblast cell line (NIH3T3) were visualized by tomographic imaging at approximately 60 nm resolution without the need for sectioning or staining. The overall structure consisted of a high electron density region, composed of the outer and inner membranes and the cristae cluster, which enclosed the lower density mitochondrial matrix. The average mass density of the mitochondrion was about 1.36 g/cm3. Sectioned images of the cristae reveal that they have neither a baffle nor septa shape but were instead irregular. In addition, a high resolution, about 14 nm, 2D projection image was captured of a similar mitochondrion with the aid of strongly scattering Au reference objects. Obtaining 3D images at this improved resolution will allow CXDI to be an effective and nondestructive method for investigating the innate structure of mitochondria and other important life supporting organelles.
Metazoan Ribosome Inactivating Protein encoding genes acquired by Horizontal Gene Transfer
Authors: Lapadula Walter J. , Marcet Paula L. , Mascotti María L. , Sanchez-Puerta M. Virginia , Juri Ayub Maximiliano
Published: May 2017

Ribosome inactivating proteins (RIPs) are RNA N-glycosidases that depurinate a specific adenine residue in the conserved sarcin/ricin loop of 28S rRNA. These enzymes are widely distributed among plants and their presence has also been confirmed in several bacterial species. Recently, we reported for the first time in silico evidence of RIP encoding genes in metazoans, in two closely related species of insects: Aedes aegypti and Culex quinquefasciatus. Here, we have experimentally confirmed the presence of these genes in mosquitoes and attempted to unveil their evolutionary history. A detailed study was conducted, including evaluation of taxonomic distribution, phylogenetic inferences and microsynteny analyses, indicating that mosquito RIP genes derived from a single Horizontal Gene Transfer (HGT) event, probably from a cyanobacterial donor species. Moreover, evolutionary analyses show that, after the HGT event, these genes evolved under purifying selection, strongly suggesting they play functional roles in these organisms.
Impact of Hepatitis C Treatment as Prevention for People Who Inject Drugs is sensitive to contact network structure
Authors: Metzig Cornelia , Surey Julian , Francis Marie , Conneely Jim , Abubakar Ibrahim , White Peter J.
Published: May 2017

Treatment as Prevention (TasP) using directly-acting antivirals has been advocated for Hepatitis C Virus (HCV) in people who inject drugs (PWID), but treatment is expensive and TasP’s effectiveness is uncertain. Previous modelling has assumed a homogeneously-mixed population or a static network lacking turnover in the population and injecting partnerships. We developed a transmission-dynamic model on a dynamic network of injecting partnerships using data from survey of injecting behaviour carried out in London, UK. We studied transmission on a novel exponential-clustered network, as well as on two simpler networks for comparison, an exponential unclustered and a random network, and found that TasP’s effectiveness differs markedly. With respect to an exponential-clustered network, the random network (and homogeneously-mixed population) overestimate TasP’s effectiveness, whereas the exponential-unclustered network underestimates it. For all network types TasP’s effectiveness depends on whether treated patients change risk behaviour, and on treatment coverage: higher coverage requires fewer total treatments for the same health gain. Whilst TasP can greatly reduce HCV prevalence, incidence of infection, and incidence of reinfection in PWID, assessment of TasP’s effectiveness needs to take account of the injecting-partnership network structure and post-treatment behaviour change, and further empirical study is required.
Sexual homomorphism in dioecious trees: extensive tests fail to detect sexual dimorphism in Populus
Authors: McKown Athena D. , Klápště Jaroslav , Guy Robert D. , Soolanayakanahally Raju Y. , La Mantia Jonathan , Porth Ilga , Skyba Oleksandr , Unda Faride , Douglas Carl J. , El-Kassaby Yousry A. , Hamelin Richard C. , Mansfield Shawn D. , Cronk Quentin C. B.
Published: May 2017

The evolution of sexual dimorphism and expansion of sex chromosomes are both driven through sexual conflict, arising from differing fitness optima between males and females. Here, we pair work in poplar (Populus) describing one of the smallest sex-determining regions known thus far in complex eukaryotes (~100 kbp) with comprehensive tests for sexual dimorphism using >1300 individuals from two Populus species and assessing 96 non-reproductive functional traits. Against expectation, we found sexual homomorphism (no non-reproductive trait differences between the sexes), suggesting that gender is functionally neutral with respect to non-reproductive features that affect plant survival and fitness. Combined with a small sex-determining region, we infer that sexual conflict may be effectively stymied or non-existent within these taxa. Both sexual homomorphism and the small sex-determining region occur against a background of strong environmental selection and local adaptation in Populus. This presents a powerful hypothesis for the evolution of dioecious species. Here, we suggest that environmental selection may be sufficient to suppress and stymy sexual conflict if it acts orthogonal to sexual selection, thereby placing limitations on the evolution of sexual dimorphism and genomic expansion of sex chromosomes.
Spatial topologies affect local food web structure and diversity in evolutionary metacommunities
Authors: Bolchoun Lev , Drossel Barbara , Allhoff Korinna Theresa
Published: May 2017

An important challenge in theoretical ecology is to better predict ecological responses to environmental change, and in particular to spatial changes such as habitat fragmentation. Classical food-web models have focused on purely ecological predictions, without taking adaptation or evolution of species traits into account. We address this issue using an eco-evolutionary model, which is based on body masses and diets as the key traits that determine metabolic rates and trophic interactions. The model implements evolution by the introduction of new morphs that are related to the existing ones, so that the network structure itself evolves in a self-organized manner. We consider the coupling and decoupling of habitats in multi-trophic metacommunities consisting of 2 or 4 habitats. Our model thus integrates metacommunity models, which describe ecosystems as networks of networks, with large community evolution models. We find that rescue effects and source-sink effects occur within coupled habitats, which have the potential to change local selection pressures so that the local food web structure shows a fingerprint of its spatial conditions. Within our model system, we observe that habitat coupling increases the lifetimes of top predators and promotes local biodiversity.