bluuebunny/crossref_metadata_2025_split huggingface dataset:
Parametric resonance in the dynamics of an elliptic vortex in a periodically strained environment
Authors: Koshel Konstantin V. , Ryzhov Eugene A. 
Published: January 2017

Abstract. The model of an elliptic vortex evolving in a periodically strained background flow is studied in order to establish the possible unbounded regimes. Depending on the parameters of the exterior flow, there are three classical regimes of the elliptic vortex motion under constant linear deformation: (i) rotation, (ii) nutation, and (iii) infinite elongation. The phase portrait for the vortex dynamics features critical points which correspond to the stationary vortex not changing its form and orientation. We demonstrate that, given superimposed periodic oscillations to the exterior deformation, the phase space region corresponding to the elliptic critical point experiences parametric instability leading to locally unbounded dynamics of the vortex. This dynamics manifests itself as the vortex nutates along the strain axis while continuously elongating. This motion continues until nonlinear effects intervene near the region associated with the steady-state separatrix. Next, we show that, for specific values of the perturbation parameters, the parametric instability is effectively suppressed by nonlinearity in the primal parametric instability zone. The secondary zone of the parametric instability, on the contrary, produces an effective growth of the vortex's aspect ratio.
CURE CHARACTERISTICS OF DEVULCANIZED RUBBER:THE ISSUE OF LOW SCORCH
Authors: Joseph Anu Mary , George Benny , Madhusoodanan K. N. , Alex Rosamma 
Published: January 2017

ABSTRACT
We investigate the reasons behind the observed low scorch during the revulcanization of devulcanized rubber. Mechanically devulcanized carbon black filled natural rubber vulcanizates originally cured by conventional vulcanization (CV), semiefficient vulcanization (semi EV), efficient vulcanization (EV), and peroxide systems as well as buffing dust obtained from pre-cured tread with known formulation were used. Revulcanization of these devulcanized samples using sulfur/sulfonamide system led to the following observations; irrespective of the type of sulfur cure system used for the initial vulcanization of the rubber, (i) the devulcanized samples cured without pre-vulcanization induction time and (ii) devulcanized samples prepared from peroxide vulcanized rubber cured with scorch safety. Based on the earlier reports that solvent extraction of devulcanized rubber did not improve the scorch time during revulcanization, the role of zinc bound non-extractable moieties was investigated using devulcanized rubber prepared from activator-free vulcanizates, which disproved the role of such moieties. This confirmed that the scorch reducing moieties should be attached to the rubber main chain, which can be unreacted crosslink precursors and cyclic sulfides left after the initial accelerated sulfur vulcanization of the original sample. The ability of pre-vulcanization inhibitor to induce scorch safety when devulcanized rubber is revulcanized as such, without adding any virgin rubber, proved that mercaptobenzothiazole (MBT) generated from crosslink precursors is the cause of low scorch. Acetone extracted devulcanized rubber samples prepared from tetramethyl thiuramdisulfide (TMTD) cured natural rubber, which does not follow the MBT pathway when revulcanized, cured with scorch safety, which further proved the role of MBT. Based on the previous reports and our results, it is obvious that powdering of rubber vulcanizate and devulcanization processes have no role on the low process safety of these materials, but it is inherent to the initial accelerated sulfur vulcanization chemistry undergone by these materials.
Efficacy of using Zaontz urethral stent in hypospadias repair by the Face, Legs, Activity, Cry, Consolability (FLACC) scale: A prospective study
Authors: Ozcan Serkan , Bagcioglu Murat , Karakan Tolga , Diri Mehmet Akif , Demirbas Arif 
Published: January 2017

Introduction: The developments in hypospadias surgical techniques and materials are intended to improve surgery outcomes and patient comfort. The aim of this study is to determine the effect of the Zaontz urethral stent (ZUS) (Cook Medical) on patient comfort and surgical success rates in children undergoing hypospadias surgery.Methods: A feeding tube was used to repair 46 cases of primary distal hypospadias, and ZUS (6F, 8F, and 10F in diameter) was used to repair to 31 cases of primary distal hypospadias between December 2009 and June 2011 in our clinic. ZUS was compared with the feeding tube in terms of surgical success rates and patient comfort in assessments made during postoperative periods.Results: The patients with ZUS were followed with a stent for seven days postoperatively, as were the patients with the feeding tube. There was no statistical difference between the two groups in terms of fistula formation (p>0.05). Patient comfort was evaluated by the Face, Legs, Activity, Cry, Consolability (FLACC) scale on the first and third postoperative days, and a statistically significant difference was observed in favour of ZUS on the third postoperative day (p<0.05).Conclusions: Compared with a feeding tube in hypospadias repair, ZUS does not make any contribution to the urinary fistula rates. However, ZUS may have an advantage in terms of patient comfort in the postoperative followup. On the other hand, the small number of patients and the high price of the ZUS were the most important limitations. Prospective, randomized trials are needed to assess efficacy and cost.
Innovación en la formación inicial del profesorado: exploración de creencias sobre la enseñanza de las Ciencias Sociales en alumnos de Magisterio
Authors: Feliu Torruella María , Vallés Sisamón Alba , Cardona Gómez Gemma 
Published: January 2017

<p>La formación inicial del profesorado se sitúa como una variable de gran influencia para promover cambios en las aulas de nuestras escuelas. Es por ello que el presente artículo quiere contribuir a la innovación y mejora de este ámbito replanteando los planes docentes de algunas de las asignaturas del grado de magisterio. Los cambios de estos planes docentes estarán basados en la exploración de creencias e ideas de un grupo de 295 estudiantes de esta carrera en la Universidad de Barcelona. Concretamente, el objetivo de este trabajo es conocer las creencias que mantienen los estudiantes sobre el tipo de metodologías que utilizarían para impartir sus clases de Ciencias Sociales. Esta exploración se realizó a través de un cuestionario elaborado por el propio equipo de investigación. Los resultados muestran que los estudiantes mantienen creencias mixtas sobre cómo enseñar ya que consideran importantes tanto estrategias de carácter constructivo como de carácter transmisivo. Aparecen también diferencias significativas entre las valoraciones de los alumnos de primero y cuarto de carrera. Acorde con los resultados, presentamos algunas líneas de actuación interesantes para abordar el replanteamiento de la formación inicial en el ámbito de la didáctica de las Ciencias Sociales. </p>
Wet chemical preparation and isotope exchange process of H/D-terminated Si(111) and Si(110) studied by adsorbate vibrational analysis
Authors: Kawamoto Erina , Kang Jungmin , Matsuda Takuya , Yamada Taro , Suto Shozo 
Published: January 2017

Abstract
A convenient procedure for preparing D-terminated Si(111)-(1×1) and Si(110)-(1×1) by wet chemical etching was developed and applied to the vibrational analysis of these surfaces by high-resolution electron-energy loss spectroscopy (HREELS). Fully H-terminated Si(111)/(110) was first prepared in regular 40% NH4F/H2O solution, followed by immersion in saturated KF/D2O solution. HREELS revealed partially D-terminated H:Si(111)/(110) with the amount of deuterium termination depending on the immersion time. A series of various immersion times revealed the H/D exchange reaction kinetics, which are associated with the Si substrate etching processes on Si(111) (step-flow etching) and Si(110) (zipper reaction). The H–Si and D–Si stretching vibration frequencies as functions of the surface D fraction did not appear to change on Si(111), but on Si(110) the H–Si signal red shifted at a high D fraction. This is due to the adsorbate–adsorbate interaction, which is more intense on Si(110) because of the short nearest-neighbor distance of the adsorbates.
Why choose Random Forest to predict rare species distribution with few samples in large undersampled areas? Three Asian crane species models provide supporting evidence
Authors: Mi Chunrong , Huettmann Falk , Guo Yumin , Han Xuesong , Wen Lijia 
Published: January 2017

Species distribution models (SDMs) have become an essential tool in ecology, biogeography, evolution and, more recently, in conservation biology. How to generalize species distributions in large undersampled areas, especially with few samples, is a fundamental issue of SDMs. In order to explore this issue, we used the best available presence records for the Hooded Crane (Grus monacha,n = 33), White-naped Crane (Grus vipio,n = 40), and Black-necked Crane (Grus nigricollis,n = 75) in China as three case studies, employing four powerful and commonly used machine learning algorithms to map the breeding distributions of the three species: TreeNet (Stochastic Gradient Boosting, Boosted Regression Tree Model), Random Forest, CART (Classification and Regression Tree) and Maxent (Maximum Entropy Models). In addition, we developed an ensemble forecast by averaging predicted probability of the above four models results. Commonly used model performance metrics (Area under ROC (AUC) and true skill statistic (TSS)) were employed to evaluate model accuracy. The latest satellite tracking data and compiled literature data were used as two independent testing datasets to confront model predictions. We found Random Forest demonstrated the best performance for the most assessment method, provided a better model fit to the testing data, and achieved better species range maps for each crane species in undersampled areas. Random Forest has been generally available for more than 20 years and has been known to perform extremely well in ecological predictions. However, while increasingly on the rise, its potential is still widely underused in conservation, (spatial) ecological applications and for inference. Our results show that it informs ecological and biogeographical theories as well as being suitable for conservation applications, specifically when the study area is undersampled. This method helps to save model-selection time and effort, and allows robust and rapid assessments and decisions for efficient conservation.
Diversity and distribution of the Caddisflies (Insecta: Trichoptera) of Ecuador
Authors: Ríos-Touma Blanca , Holzenthal Ralph W. , Huisman Jolanda , Thomson Robin , Rázuri-Gonzales Ernesto 
Published: January 2017

BackgroundAquatic insects and other freshwater animals are some of the most threatened forms of life on Earth. Caddisflies (Trichoptera) are highly biodiverse in the Neotropics and occupy a wide variety of freshwater habitats. In Andean countries, including Ecuador, knowledge of the aquatic biota is limited, and there is a great need for baseline data on the species found in these countries. Here we present the first list of Trichoptera known from Ecuador, a country that harbors two global biodiversity “hotspots.”MethodsWe conducted a literature review of species previously reported from Ecuador and supplemented these data with material we collected during five recent field inventories from about 40 localities spanning both hotspots. Using species presence data for each Ecuadorian province, we calculated the CHAO 2 species estimator to obtain the minimum species richness for the country.ResultsWe recorded 310 species, including 48 new records from our own field inventories for the country. CHAO 2 calculations showed that only 54% of the species have been found. Hydroptilidae and Hydropsychidae were the most species rich families. We report the family Xiphocentronidae for the first time from Ecuador as well as several new records of genera from different families.DiscussionAs in the neighboring Andean countries of Colombia and Peru, it is common to find undescribed species of caddisflies. There are vast areas of Ecuador and the northern Andes that are completely unexplored, and we expect that hundreds of new species are yet to be discovered.
Italian and Swedish adolescents: differences and associations in subjective well-being and psychological well-being
Authors: Garcia Danilo , Sagone Elisabetta , De Caroli Maria Elvira , Nima Ali Al 
Published: January 2017

BackgroundOne important aspect of subjective judgments about one’s well-being (i.e., subjective well-being: life satisfaction, positive affect, and negative affect) is that cultural features, such as, nationality seem to shape cognitive judgments about the “the ideal life.” In this comparative study we examined differences in subjective well-being and psychological well-being between Italian and Swedish adolescents and tested if the relationship between the three constructs of subjective well-being (i.e., satisfaction with life, positive affect, and negative affect) and psychological well-being was moderated by the adolescents’ nationality.MethodItalian (n= 255) and Swedish (n= 277) adolescents answered to the Satisfaction with Life Scale, the Positive Affect Negative Affect Schedule, and Ryff’s Scales of Psychological Well-Being. Differences between samples were tested using a Multiple Analysis of Variance. We also conducted a multiple group analysis (Italy and Sweden) using Structural Equation Modelling to investigate the relationship between all three subjective well-being constructs and psychological well-being.ResultsItalian adolescents scored significantly higher in satisfaction with life than Swedish adolescents. Additionally, across countries, girls scored significantly higher in negative affect than boys. In both countries, all three constructs of subjective well-being were significantly associated to adolescents’ psychological well-being. Nevertheless, while the effect of the relationship between affect and psychological well-being was almost the same across countries, life satisfaction was more strongly related to psychological well-being among Swedish adolescents.ConclusionsThe present study shows that there are larger variations between these two cultures in the cognitive construct of subjective well-being than in the affective construct. Accordingly, associations between the cognitive component, not the affective component, of subjective well-being and psychological well-being differ between countries as well.
Morphology of high‐latitude plasma density perturbations as deduced from the total electron content measurements onboard the Swarm constellation
Authors: Park Jaeheung , Lühr Hermann , Kervalishvili Guram , Rauberg Jan , Stolle Claudia , Kwak Young‐Sil , Lee Woo Kyoung 
Published: January 2017

AbstractIn this study, we investigate the climatology of high‐latitude total electron content (TEC) variations as observed by the dual‐frequency Global Navigation Satellite Systems (GNSS) receivers onboard the Swarm satellite constellation. The distribution of TEC perturbations as a function of geographic/magnetic coordinates and seasons reasonably agrees with that of the Challenging Minisatellite Payload observations published earlier. Categorizing the high‐latitude TEC perturbations according to line‐of‐sight directions between Swarm and GNSS satellites, we can deduce their morphology with respect to the geomagnetic field lines. In the Northern Hemisphere, the perturbation shapes are mostly aligned with the L shell surface, and this anisotropy is strongest in the nightside auroral (substorm) and subauroral regions and weakest in the central polar cap. The results are consistent with the well‐known two‐cell plasma convection pattern of the high‐latitude ionosphere, which is approximately aligned with L shells at auroral regions and crossing different L shells for a significant part of the polar cap. In the Southern Hemisphere, the perturbation structures exhibit noticeable misalignment to the local L shells. Here the direction toward the Sun has an additional influence on the plasma structure, which we attribute to photoionization effects. The larger offset between geographic and geomagnetic poles in the south than in the north is responsible for the hemispheric difference.
Modeling the plasmasphere based on LEO satellites onboard GPS measurements
Authors: Chen Peng , Yao Yibin , Li Qinzheng , Yao Wanqiang 
Published: January 2017

AbstractThe plasmasphere, which is located above the ionosphere, is a significant component of Earth's atmosphere. A global plasmaspheric model was constructed using the total electron content (TEC) along the signal propagation path calculated using onboard Global Positioning System observations from the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) and MetOp‐A, provided by the COSMIC Data Analysis and Archive Center (CDAAC). First, the global plasmaspheric model was established using only COSMIC TEC, and a set of MetOp‐A TEC provided by CDAAC served for external evaluation. Results indicated that the established model using only COSMIC data is highly accurate. Then, COSMIC and MetOp‐A TEC were combined to produce a new global plasmaspheric model. Finally, the variational characteristics of global plasmaspheric electron content with latitude, local time, and season were investigated using the global plasmaspheric model established in this paper.
Silver‐Catalyzed Chemoselective [4+2] Annulation of Two Isocyanides: A General Route to Pyridone‐Fused Carbo‐ and Heterocycles
Authors: Hu Zhongyan , Dong Jinhuan , Men Yang , Lin Zhichen , Cai Jinxiong , Xu Xianxiu 
Published: January 2017

AbstractA silver‐catalyzed chemoselective [4+2] annulation of aryl and heteroaryl isocyanides with α‐substituted isocyanoacetamides was developed for the facile and efficient synthesis of 2‐aminoquinolones, naphthyridines, and phenanthrolines. A mechanism for this multistep domino reaction is proposed on the basis of a 13C‐labeling experiment, according to which an unprecedented chemoselective heterodimerization of two different isocyanides generates an α‐amidoketenimine intermediate, which undergoes 1,3‐amino migration to form an α‐imidoylketene, followed by 6 π electrocyclization.
Mangan‐katalysierte Mehrkomponentensynthese von Pyrimidinen aus Alkoholen und Amidinen
Authors: Deibl Nicklas , Kempe Rhett 
Published: January 2017

AbstractDie Entwicklung von neuartigen, vorzugsweise katalytischen Reaktionen, um Verbindungsklassen ausgehend von Alkoholen herzustellen, ist von hoher Bedeutung, da sie zur Erhaltung der fossilen Kohlenstoffressourcen und zur Reduktion von CO2‐Emissionen beiträgt. Um die extrem seltenen Edelmetallressourcen zu schonen, ist der Ersatz von seltenen Metallen wie Ir, Rh oder Pt durch breit verfügbare 3d‐Metalle in Schlüsseltechnologien wie der Katalyse ebenso wichtig. Wir berichten hier über eine durch einen Mangankomplex katalysierte Version der Mehrkomponentensynthese von Pyrimidinen aus Amidinen und drei (unterschiedlichen) Alkoholen. Die Reaktion verläuft über Kondensations‐ und Dehydrierungsschritte, was selektive C‐C‐und C‐N‐Bindungsknüpfungen erlaubt. Wir nutzen selektive β‐Alkylierungen, um sekundäre Alkohole mehrfach mit unterschiedlichen primären Alkoholen zu alkylieren, um vollständig substituierte Pyrimidine in einem Eintopfprozess zu synthetisieren. PN5P‐Mn‐Pincer‐Komplexe, die in unserem Labor entwickelt wurden, katalysieren diesen nachhaltigen Mehrkomponentenprozess am effizientesten. Ein Vergleich unserer Mangankomplexe mit verwandten Cobaltkomplexen zeigt, dass Mangan der katalytischen Reaktivität von Iridium nahekommt, Cobalt jedoch nicht. Wir erwarten, dass diese Analogie dazu genutzt werden kann, weitere katalytische Anwendungen von Mangankomplexen zu entwickeln, bei denen Hydrierungs‐ oder Dehydrierungsschritte involviert sind.
Stable and Rapid Thiol Bioconjugation by Light‐Triggered Thiomaleimide Ring Hydrolysis
Authors: Kalia Dimpy , Pawar Sharad P. , Thopate Jyoti S. 
Published: January 2017

AbstractMaleimide‐mediated thiol‐specific derivatization of biomolecules is one of the most efficacious bioconjugation approaches currently available. Alarmingly, however, recent work demonstrates that the resulting thiomaleimide conjugates are susceptible to breakdown via thiol exchange reactions. Herein, we report a new class of maleimides, namely o‐CH2NHiPr phenyl maleimides, that undergo unprecedentedly rapid ring hydrolysis after thiol conjugation to form stable thiol exchange‐resistant conjugates. Furthermore, we overcome the problem of low shelf lives of maleimide reagents owing to their propensity to undergo ring hydrolysis prior to bioconjugation by developing a photocaged version of this scaffold that resists ring hydrolysis. UV irradiation of thiol bioconjugates formed with this photocaged maleimide unleashes rapid thiomaleimide ring hydrolysis to yield the desired stable conjugates within 1 h under gentle, ice‐cold conditions.
Photoisomerization of a Chiral Imine Molecular Switch Followed by Matrix‐Isolation VCD Spectroscopy
Authors: Pollok Corina H. , Riesebeck Tim , Merten Christian 
Published: January 2017

AbstractCharacterizing the stereochemistry of transient photoisomerization products remains a big challenge for the design of molecular machines, such as unidirectional molecular motors. Often these states are not stable long enough to be characterized in detail using conventional spectroscopic tools. The structurally simple camphorquinone imine 1 serves to illustrate the advantage of combining the matrix‐isolation technique with vibrational circular dichroism (VCD) spectroscopy for the investigation of photoisomerizations of chiral molecules. In particular, it is shown that both (E)‐ and (Z)‐1 can be generated photochemically at cryogenic temperatures in an argon matrix, and more importantly, that the stereochemistry of both switching states can be characterized reliably.
Mn(III)–pentadentate Schiff base complex supported on multi‐walled carbon nanotubes as a green, mild and heterogeneous catalyst for the synthesis of tetrahydrobenzo[b]pyrans via tandem Knoevenagel–Michael cyclocondensation reaction
Authors: Rakhtshah Jamshid , Salehzadeh Sadegh , Zolfigol Mohammad Ali , Baghery Saeed 
Published: January 2017

Mn(III)–pentadentate Schiff base complex supported on multi‐walled carbon nanotubes as a recyclable and reusable, green and nano‐heterogeneous catalyst was designed and fully characterized using infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, inductively coupled plasma mass spectrometry, elemental analysis and thermogravimetric analysis. A facile, eco‐friendly, mild and green procedure was developed for the one‐pot three‐component synthesis of tetrahydrobenzo[b]pyrans via tandem Knoevenagel–Michael cyclocondensation reactions between aromatic aldehydes, 1,3‐diones and malononitrile using a catalytic amount of Mn(III)–pentadentate Schiff base complex supported on MWCNTs as an efficient recyclable heterogeneous catalyst under solvent‐free conditions at room temperature. This process has the advantages of easy availability, stability, recyclability and eco‐friendliness of the catalyst, short reaction times, high to excellent yields and simple work‐up procedure.