bluuebunny/crossref_metadata_2025 huggingface dataset:
A Study on the Mobile Learning of English and American Literature Based on Wechat Public Account
Authors: Dai Guiyu , Liu Yang , Cui Shanmeng
Published: May 2018

This paper uses Edgar Dale’s Audio-visual Learning Theory and Jean Piaget’s Constructionist Learning Theory as the theoretical framework to conduct two control experimental tests and a questionnaire research to investigate students’ impression and expectations toward Wechat public account based mobile learning mode as well as its validity, advantages and shortcomings. The findings of the research are as follows: (1) students who use the WeChat public account based mobile learning mode can perform better in acquiring knowledge and passing examinations than non-users; (2) students’ mobile learning habits find a good basis for their acceptance of the new WeChat learning mode; (3) most students respond to the new WeChat learning mode with a positive attitude, and universities can introduce this mode into the course design; (4) this new WeChat learning mode helps students learn literature in the aspects of interest stimulation, ability improvement and literature content learning; (5) WeChat mobile learning is only an extension of the current form of learning and cannot replace the current traditional school education; (6) Mobile learning mode based WeChat public account is an important teaching aid for teachers in the aspects of information dissemination, interactive mode and updated contents; (7) The experience of improving the current mobile learning model of WeChat public account can be enriched from students’ feedback. It is hoped that WeChat mobile learning will efficiently activate students’ learning potentials and promote English and American literature teaching innovation.
What Are the Factors Affecting the Use of English Language in English-only Classrooms: Student’s Perspectives in Pakistan
Authors: Asif Sadia , Bashir Rahat , Zafar Shabana
Published: May 2018

English as a medium of instruction and communication is becoming a central pedagogy in various countries in the world. In Pakistan, most of the advanced academic institutions use English as their medium of instruction, however students and teachers have been observed communicating in their first languages, especially Urdu, in the classrooms. This study was conducted at the Institute of Communication and Cultural Studies, University of Management and Technology, to examine the factors that limit students and teachers from communicating in English. Qualitative research methods were employed to find the factors affecting the use of English in English-only classrooms. A total of 130 participants were included in this study. Among them, 68 participants were engaged in student questionnaires. The participants were students of four native languages (Urdu, Punjabi, Siraiki and Pushto) with different level of English language proficiency. Required literature search was performed using key databases and journals, related to applied linguistics, English language and education. Our results demonstrated that most of the students like to communicate in English and be a part of the English-only environment, however they acknowledged some key factors that prevented them from speaking English in the classrooms. Fundamental factors included linguistics, individual, social, psychological and institutional which were largely based upon their beliefs, assumptions, needs and desires. This study may provide insights to the policymakers to work on issues related to communications and medium of instructions in Pakistan. It may also help teachers and educators to understand the underlying factors that compel students to speak their first languages instead of English.
Behavioral Perspectives on Risk Prone Behavior: Why Do People Take Risks?
Authors: Wolf Shelby , Houlihan Daniel
Published: May 2018

Utilizing the principles and concepts of behavioral economics and operant psychology, researchers in both fields initiated the creation of the optimal foraging theory. This theory describes foraging behaviors mostly within animals other than humans. However, within recent empirical studies, optimal foraging theory has been modified to explain risky choices and decision-making processes within the context of risk-sensitive foraging theory for both animals and humans alike. Although most individuals belonging to the homo sapiensspecies would not like to admit that their behavior is very animalistic in nature, there is a great deal of veracity behind this idea, ranging from explaining gambling behavior to addictive behaviors to even homicide. Risk prone behavior describes behavior elicited for the potential gain of rewards under certain conditions, usually competitive in nature. The purpose of the current paper is to shed some light on this topic and how it relates to the most primitive of behaviors exhibited by human beings.
Estimation of skin permeation by liquid chromatography
Authors: Soriano-Meseguer Sara , Fuguet Elisabet , Port Adriana , Rosés Martí
Published: May 2018

Dermal absorption is a key process in the drug delivery studies of the pharmaceutical and cosmetic industries, as well as in the fields of dermal toxicology, risk assessment, and the exposure of environmental pollutants. This process is typically described by the skin-water permeability coefficient. However, in vivo determination is laborious and expensive. Thus, in the last few years, the development of prediction models from structure descriptors or subrogation through physico-chemical measurements has gained interest. In the present work, a previous subrogation model based on the chromatographic retention on a common C18 column has been tested for a wide set of drugs with very different chemical nature and having a wide range of permeability values. A total of 65 compounds have been used to establish the correlation between skin permeation and the HPLC retention, corrected by the McGowan volume of the drug. Afterwards it was successfully validated in terms of robustness and prediction ability. Finally, the permeability coefficient was estimated for a set of 29 new drugs, and results compared to the ones obtained by other estimation methods, as well as the available in vitro measured values, with very good agreement.
Visual Similarity Perception of Directed Acyclic Graphs: A Study on Influencing Factors and Similarity Judgment Strategies
Authors: Ballweg Kathrin , Pohl Margit , Wallner Günter , Von Landesberger Tatiana
Published: May 2018

Visual comparison of directed acyclic graphs (DAGs) is commonly encountered in various disciplines (e.g., finance, biology). Still, knowledge about humans' perception of their similarity is currently quite limited. By similarity perception, we mean how humans perceive commonalities and differences of DAGs and herewith come to a similarity judgment. To fill this gap, we strive to identify factors influencing the DAG similarity perception. Therefore, we conducted a card sorting study employing a quantitative and qualitative analysis approach to identify (1) groups of DAGs the participants perceived as similar and (2) the reasons behind their groupings. We also did an extended analysis of our collected data to (1) reveal specifics of the influencing factors and (2) investigate which strategies are employed to come to a similarity judgment. Our results suggest that DAG similarity perception is mainly influenced by the number of levels, the number of nodes on a level, and the overall shape of the DAG. We also identified three strategies used by the participants to form groups of similar DAGs: divide and conquer, respecting the entire dataset and considering the factors one after the other, and considering a single factor. Factor specifics are, e.g., that humans on average consider four factors while judging the similarity of DAGs. Building an understanding of these processes may inform the design of comparative visualizations and strategies for interacting with them. The interaction strategies must allow the user to apply her similarity judgment strategy to the data. The considered factors bear information on, e.g., which factors are overlooked by humans and thus need to be highlighted by the visualization.
Reconstructing Generalized Staircase Polygons with Uniform Step Length
Authors: Sitchinava Nodari , Strash Darren
Published: May 2018

Visibility graph reconstruction, which asks us to construct a polygon that has a given visibility graph, is a fundamental problem with unknown complexity (although visibility graph recognition is known to be in PSPACE).
As far as we are aware, the only class of orthogonal polygons that are known to have efficient reconstruction algorithms is the class of orthogonal convex fans (staircase polygons) with uniform step lengths.
We show that two classes of uniform step length polygons can be reconstructed efficiently by finding and removing rectangles formed between consecutive convex boundary vertices called tabs.
In particular, we give an $O(n^2m)$-time reconstruction algorithm for orthogonally convex polygons,
where $n$ and $m$ are the number of vertices and edges in the visibility graph, respectively.
We further show that reconstructing a monotone chain of staircases (a histogram) is fixed-parameter tractable, when parameterized on the number of tabs, and polynomially solvable in time $O(n^2m)$ under alignment restrictions.
As a consequence of our reconstruction techniques, we also get recognition algorithms for visibility graphs of these classes of polygons with the same running times.
The influence of Pleistocene dynamics on the South African salt marsh species Sarcocornia pillansii (Moss) A. J. Scott (Amaranthaceae): Inferences from phylogeography and species distribution modelling
Authors: Veldkornet Dimitri A , Rajkaran Anusha , Adams Janine B
Published: May 2018

Glacial–interglacial climate oscillations during the Pleistocene played a significant role in shifting species distributions. During this period (26 500 - 19 000 years ago) the sea level was 120 m lower than it is currently with large areas of the Southern African continental shelf being exposed. This formed a barrier to cold-water dispersal of various aquatic organisms between the west and east coast. This study explores the influence of past climatic conditions on the salt marsh species Sarcocornia pillansii (Moss) A. J. Scott using species distribution modelling and multi-locus phylogeography. The area under curve (AUC) values were considered ‘good’ (> 0.80), indicating that the models had high specificity and sensitivity. The AUC was greater for the Maxent model (AUC = 0.881) compared to the Bioclim model (AUC = 0.837) under current conditions. Climate simulation of the Last Glacial Maximum (LGM) indicated greatest habitat suitability in estuaries along the west (Orange River Estuary to Langebaan) and east (Algoa Bay to Keiskamma) coast of South Africa. This pattern is reflected in the phylogeographic analysis where a greater number of haplotypes were found in estuaries west and east of the greater continental shelf. The nuclear DNA dataset that included 97 sequences eight ribotypes whereas the chloroplast DNA for 94 sequences that were resolved into four haplotypes. The results suggest that species survived in these estuaries (as refugia) during Pleistocene climate cycles. Post-LGM increases in sea level along the south coast allowed confluence between isolated river systems, offering opportunities for dispersal among populations.
Conserved mass peaks in MALDI-TOF mass spectra of bacterial species at the genus and species levels
Authors: Ng Wenfa
Published: May 2018

Microbes are identified based on their distinguishing characteristics such as gene sequence or metabolic profile. Nucleic acid approaches such as 16S rRNA gene sequencing provide the gold standard method for microbial identification in the contemporary era. However, mass spectrometry-based microbial identification is gaining credence through ease of use, speed, and reliability. Specifically, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been used in identifying bacteria, fungus, molds and archaea to the species level with high accuracy. The approach relies on the existence of unique mass spectrum fingerprint for individual microbial species. By comparing the mass spectrum of an unknown microbe with that catalogued in a reference database of known microorganisms, microbes could be identified through mass spectrum fingerprinting. However, the approach lacks fundamental biological basis given the relative difficulty in assigning specific protein to particular mass peak in the profiled mass spectrum, which hampers a deeper understanding of the mass spectrum obtained. This study seeks to examine the existence of conserved mass peaks in MALDI-TOF mass spectra of bacteria at the species and genus levels using open access data from SpectraBank. Results revealed that conserved mass peaks existed for all bacterial species examined. Large number of conserved mass peaks such as that of Escherichia coli and Morganella morganii suggested more closely-related strains of a species though functional annotation of the mass peaks is required to provide a deeper understanding of the mechanisms underlying the conservation of specific proteins. On the other hand, strains of Staphylococcus aureus and Pseudomonas putida had the least number of conserved mass peaks. Presence of conserved mass peaks in many genus provided further evidence that MALDI-TOF MS microbial identification had a biological basis in identification of microbial species to the genus level. In addition, it also highlighted that a subset of proteins could define the taxonomical boundary between the species and genus level. Finally, existence of only one conserved mass peak in Bacillus genus corroborated the difficulty of discriminating Bacillus species based on MALDI-TOF mass spectra. Similarly, no conserved mass peak at the genus level could be found for the Staphylococcus genus. Overall, existence of conserved mass peaks of bacteria at the species and genus levels provided evidence of a firm biological basis in the mass spectrum fingerprinting approach of MALDI-TOF MS microbial identification. This could help identify specific species in mass spectrum of single or multiple microbial species. Further functional annotation of the conserved mass peaks could illuminate in greater detail the biological mysteries of why certain proteins are conserved in specific genus and species.
Evaluation of prototype of improved electron collimation system for Elekta linear accelerators
Authors: Pitcher Garrett M. , Hogstrom Kenneth R. , Carver Robert L.
Published: May 2018

Purpose

This study evaluated a new electron collimation system design for Elekta 6–20 MeV beams, which should reduce applicator weights by 25%–30%. Such reductions, as great as 3.9 kg for the largest applicator, should result in considerably easier handling by members of the radiotherapy team.

Methods

Prototype 10 × 10 and 20 × 20‐cm2 applicators, used to measure weight, in‐field flatness, and out‐of‐field leakage dose, were constructed according to the previously published design with two minor modifications: (a) rather than tungsten, lead was used for trimmer material; and (b) continuous trimmer outer‐edge bevel was approximated by three steps. Because of lead plate softness, a 0.32‐cm aluminum plate replaced the equivalent lead thickness on the trimmer's downstream surface for structural support. Models of all applicators (6 × 6–25 × 25 cm2) with these modifications were inserted into a Monte Carlo (MC) model for dose calculations using 7, 13, and 20 MeV beams. Planar dose distributions were measured and calculated at 1‐ and 2‐cm water depths to evaluate in‐field beam flatness and out‐of‐field leakage dose.

Results

Prototype 10 × 10 and 20 × 20‐cm2 applicator measurements agreed with calculated weights, in‐field flatness, and out‐of‐field leakage doses for 7, 13, and 20 MeV beams. Also, MC dose calculations showed that all applicators (6 × 6–25 × 25 cm2) and 7, 13, and 20 MeV beams met our stringent in‐field flatness specifications (±3% major axes; ±4% diagonals) and IEC out‐of‐field leakage dose specifications.

Conclusions

Our results validated the new electron collimating system design for Elekta 6–20 MeV electron beams, which could serve as basis for a new clinical electron collimating system with significantly reduced applicator weights.
Biopolymers for Antitumor Implantable Drug Delivery Systems: Recent Advances and Future Outlook
Authors: Talebian Sepehr , Foroughi Javad , Wade Samantha J. , Vine Kara L. , Dolatshahi‐Pirouz Alireza , Mehrali Mehdi , Conde João , Wallace Gordon G.
Published: May 2018

In spite of remarkable improvements in cancer treatments and survivorship, cancer still remains as one of the major causes of death worldwide. Although current standards of care provide encouraging results, they still cause severe systemic toxicity and also fail in preventing recurrence of the disease. In order to address these issues, biomaterial‐based implantable drug delivery systems (DDSs) have emerged as promising therapeutic platforms, which allow local administration of drugs directly to the tumor site. Owing to the unique properties of biopolymers, they have been used in a variety of ways to institute biodegradable implantable DDSs that exert precise spatiotemporal control over the release of therapeutic drug. Here, the most recent advances in biopolymer‐based DDSs for suppressing tumor growth and preventing tumor recurrence are reviewed. Novel emerging biopolymers as well as cutting‐edge polymeric microdevices deployed as implantable antitumor DDSs are discussed. Finally, a review of a new therapeutic modality within the field, which is based on implantable biopolymeric DDSs, is given.
Influence of Iron Catalyst in the Carbon Spheres Synthesis for Energy and Electrochemical Applications
Authors: Scarselli Manuela , Limosani Francesca , Passacantando Maurizio , D'Orazio Franco , Nardone Michele , Cacciotti Ilaria , Arduini Fabiana , Gautron Eric , De Crescenzi Maurizio
Published: May 2018

Carbon spheres of nanometric dimension are known since the first studies on the synthesis of fullerenes. Their shape originates from the curvature of a carbon sheet similar to fullerenes, but with numerous graphitic rings that regulate the inside structure and the formation of open edges at the surface. This paper focuses on the structural and electronic characterization of carbon spheres obtained from a chemical vapor deposition synthesis process. Two different sets of samples are analyzed in detail, in particular, electron microscopies and Raman spectroscopy help understanding the morphology and the graphitic‐sp2 arrangement of the carbon atoms in the architectures. In addition, the iron catalyst used during the reaction process confers the carbon spheres a ferromagnetic response at room temperature. Therefore, both the structural properties of the samples and the active contribution of iron mark the difference in the measured photoresponse as well as in the electrochemical behavior. The X‐ray photoelectron spectroscopy study addresses these points by giving information on the composition and the iron chemical state in the assembly. The collected results underline the advantages offered by this nanomaterial for sustainable applications.
Formation Mechanism, Growth Kinetics, and Stability Limits of Graphene Adlayers in Metal‐Catalyzed CVD Growth
Authors: Wang Zhu‐Jun , Ding Feng , Eres Gyula , Antonietti Markus , Schloegl Robert , Willinger Marc Georg
Published: May 2018

A new mechanism by which catalytic chemical vapor deposition of graphene spontaneously terminates at a single layer on Pt foils is discussed. This self‐limited growth regime is identified by direct imaging of adlayer graphene evolution using in‐situ environmental scanning electron microscopy. Two fundamentally different mechanisms for adlayer nucleation are revealed. Besides primary nucleation, which is the standard nucleation that occurs only at the onset of growth, a secondary nucleation of adlayers is observed near full coverage of the substrate. Direct observation reveals layer‐dependent growth kinetics and the establishment of a dynamic equilibrium between the forward reaction of carbon incorporation and the reverse reaction of graphene etching. Increasing coverage of the active catalyst gives rise to a spontaneous reversal of adlayer evolution from growth to etching. The growth reversal has important practical benefits. It creates a self‐limited growth regime in which all adlayer graphene is removed and it enables large‐scale production of 100% single‐layer graphene.
Comparing the sniffing behavior of great apes
Authors: Jänig Susann , Weiß Brigitte M. , Widdig Anja
Published: May 2018

The importance of smell in humans is well established but we know little about it in regard to our closest relatives, the great apes, as systematic studies on their olfactory behavior are still lacking. Olfaction has long been considered to be of lesser importance in hominids given their relatively smaller olfactory bulbs, fewer functional olfactory receptor genes than other species and absence of a functional vomeronasal organ. Therefore, the aim of this study was to evaluate the use of olfaction in hominids. In particular, we observed sniffing behavior in captive groups of four species (Sumatran orangutans, Pongo abelii; Western lowland gorillas, Gorilla gorilla gorilla; Western chimpanzees, Pan troglodytes verus; bonobos, Pan paniscus) and evaluated in which contexts sniffing was used. Our results show that all investigated species frequently used the sense of smell, and that the sniffing frequency varied with species, sex, age, and context. Most sniffing events were observed in gorillas in comparison to the three other species. Sniffing frequencies were also influenced by sex, with males sniffing slightly more often than females. Furthermore, our results revealed an effect of age, with younger individuals sniffing more often than older individuals. All species mainly sniffed in the non‐social context (i.e., toward food and other environmental items) rather than in the social context (i.e., at conspecifics), suggesting that the evaluation of the environment and the nutritional value of food items is of major importance to all great ape species investigated here. In contrast to the other species and female chimpanzees, however, male chimpanzees most often used olfaction to inspect their conspecifics. Together, our study suggests that olfaction is likely to be more important in great apes than previously appreciated.
Dynamics and Recovery of Genuine Multipartite Einstein–Podolsky–Rosen Steering and Genuine Multipartite Nonlocality for a Dissipative Dirac System via the Unruh Effect
Authors: Sun Wen‐Yang , Wang Dong , Ye Liu
Published: May 2018

The dynamics behaviors of genuine multipartite Einstein–Podolsky–Rosen steering (GMS) and genuine multipartite nonlocality (GMN) are investigated herein, and how the lost GMS and GMN under a mixed decoherence system can be recovered is explored. Explicitly, the decoherence system can be modeled by that a tripartite Werner‐type state suffers from the non‐Markovian regimes and one subsystem of the tripartite is under a non‐inertial frame. The conditions for steerable and nonlocal states can be obtained with respect to the tripartite Werner‐type state established initially. GMS and GMN are very fragile and vulnerable under the influence of the collective decoherence. GMS and GMN will vanish with growing intensity of the Unruh effect and the non‐Markovian reservoir. Besides, all achievable GMN's states are steerable, while not every steerable state (GMS's state) can achieve nonlocality. This means that the steering–nonlocality hierarchy is still tenable and GMN's states are a strict subset of the GMS's states in such a scenario. Subsequently, an available methodology to recover the damaged GMS and GMN is proposed. It turns out that the lost GMS and GMN can be effectively restored, and the ability of GMS and GMN to suppress the collective decoherence can be enhanced.
[Hg4Te8(Te2)4]8−: ein Schwermetall‐Porphyrinoid in einer lamellaren Struktur
Authors: Donsbach Carsten , Reiter Kevin , Sundholm Dage , Weigend Florian , Dehnen Stefanie
Published: May 2018

Die Produkte der ionothermalen Behandlung von Na2[HgTe2] in ionischen Flüssigkeiten (CnC1Im)[BF4] mit langen Alkylketten (n=10, 12) weisen lamellare Kristallstrukturen auf, deren molekulare makrocyclische Anionen, [Hg8Te16]8− (1), die schwersten bekannten topologischen Verwandten von Porphyrin darstellen. [Hg8Te16]8− unterscheidet sich von Porphyrin naturgemäß infolge des fehlenden π‐Elektronen‐Systems, weshalb auch keine “globale” Aromatizität zu beobachten ist. Quantenchemische Studien belegen jedoch (schwache) Ringströme in den Pyrrol‐artigen Fünfringen, was auf das Vorhandensein einer schwachen (σ‐)Aromatizität schließen lässt. Aufgrund ihrer lamellaren Natur könnten sich die Verbindungen zur Bildung von Einzelschichten mit solchen Chalkogenidometallat‐Anionen eignen.
Fluctuating Carbonaceous Networks with a Persistent Molecular Shape: A Saddle‐Shaped Geodesic Framework of 1,3,5‐Trisubstituted Benzene (Phenine)
Authors: Ikemoto Koki , Lin Jennie , Kobayashi Ryo , Sato Sota , Isobe Hiroyuki
Published: May 2018

A saddle‐shaped macromolecule has been synthesized. The molecule was designed as a geodesic saddle with 1,3,5‐trisubstituted benzene (named phenine) as the fundamental unit. The phenines were woven into a polygonal framework that was composed of 168 sp2‐hybridized carbon atoms. The saddle‐shaped structure with unique symmetry showed atypical conformational changes. The biaryl linkages in this molecule had a small energy barrier for rotation, and these structural fluctuations resulted in seven 1H NMR resonances representing 84 aromatic hydrogen atoms. Nevertheless, the overall saddle shape of the molecule was persistent, and the “up” and “down” orientations of phenine moieties circulated to give average 1H resonances. The structural characteristics of this molecule, including the anomalous entropy‐driven dimerization, may deepen our understanding of defect‐rich graphitic sheets.
Pinene: reichlich vorhandene und erneuerbare Bausteine für eine Vielzahl an nachhaltigen Polymeren
Authors: Winnacker Malte
Published: May 2018

Pinene – eine Gruppe von Monoterpenen, die eine Doppelbindung enthalten – sind sehr nützliche und erneuerbare Monomerbausteine für eine Vielzahl an nachhaltigen Polymeren und Materialien. Ihre Verfügbarkeit von hauptsächlich nicht‐essbaren Pflanzenteilen sowie die Leichtigkeit ihrer Isolierung machen diese Moleküle einzigartig innerhalb der Vielfalt an Biomasse, die für neue Materialien nutzbar gemacht werden kann. Dementsprechend wird ihre Verwendung für die Synthese von biobasierten Polymeren intensiv untersucht, wobei hier insbesondere in den vergangenen 2–3 Jahren starke Fortschritte erzielt wurden. Direkte kationische oder radikalische Polymerisationen über die Doppelbindungen der Pinene sowie die Polymerisation nach weiterer Funktionalisierung können eine Vielzahl an nachhaltigen Polymeren mit zahlreichen Anwendungsmöglichkeiten ergeben, was in diesem Kurzaufsatz zusammengefasst ist.
Copper‐Mediated Polymerization without External Deoxygenation or Oxygen Scavengers
Authors: Liarou Evelina , Whitfield Richard , Anastasaki Athina , Engelis Nikolaos G. , Jones Glen R. , Velonia Kelly , Haddleton David M.
Published: May 2018

As a method for overcoming the challenge of rigorous deoxygenation in copper‐mediated controlled radical polymerization processes [e.g., atom‐transfer radical polymerization (ATRP)], reported here is a simple Cu0‐RDRP (RDRP=reversible deactivation radical polymerization) system in the absence of external additives (e.g., reducing agents, enzymes etc.). By simply adjusting the headspace of the reaction vessel, a wide range of monomers, namely acrylates, methacrylates, acrylamides, and styrene, can be polymerized in a controlled manner to yield polymers with low dispersities, near‐quantitative conversions, and high end‐group fidelity. Significantly, this approach is scalable (ca. 125 g), tolerant to elevated temperatures, compatible with both organic and aqueous media, and does not rely on external stimuli which may limit the monomer pool. The robustness and versatility of this methodology is further demonstrated by the applicability to other copper‐mediated techniques, including conventional ATRP and light‐mediated approaches.
The Effect of the Active‐Site Structure on the Activity of Copper Mordenite in the Aerobic and Anaerobic Conversion of Methane into Methanol
Authors: Sushkevich Vitaly L. , Palagin Dennis , van Bokhoven Jeroen A.
Published: May 2018

Samples of the zeolite mordenite with different Si/Al ratios were used to synthesize materials with monomeric and oligomeric copper sites that are active in the direct conversion of methane into methanol. A comparison of two reactivation protocols with oxygen (aerobic oxidation) and water (anaerobic oxidation), respectively, revealed that such copper–oxo species possess different reactivity towards methane and water. We show for the first time that oligomeric copper species exhibit high activity under both aerobic and anaerobic activation conditions, whereas monomeric copper sites produce methanol only in aerobic processes.
Supramolecularly Catalyzed Polymerization: From Consecutive Dimerization to Polymerization
Authors: Tang Xiaoyan , Huang Zehuan , Chen Hao , Kang Yuetong , Xu Jiang‐Fei , Zhang Xi
Published: May 2018

Herein, we propose a new method for promoting covalent polymerization by supramolecular catalysts. To this end, we employed cucurbit[8]uril (CB[8]) as a supramolecular catalyst, and successfully prepared polyelectrolytes in an aqueous solution by taking advantage of the CB[8]‐enhanced photodimerization of Brooker merocyanine moieties. Interestingly, 10 mol % CB[8] is enough to effectively catalyze this polymerization, because CB[8] can be spontaneously replaced by terminal groups from photodimerized products. In addition, the molecular weights of the obtained polyelectrolytes can be varied by the irradiation time or the monomer. By combining supramolecular catalysis and polymer chemistry, this line of research may enrich the methodology of polymerization and open up new horizons for supramolecular polymer chemistry.
Two Bacterial Diterpene Synthases from Allokutzneria albata Produce Bonnadiene, Phomopsene, and Allokutznerene
Authors: Lauterbach Lukas , Rinkel Jan , Dickschat Jeroen S.
Published: May 2018

Two diterpene synthases from Allokutzneria albata were studied for their products, resulting in the identification of the new compound bonnadiene from the first enzyme. Although phylogenetically unrelated to fungal phomopsene synthase, the second enzyme produced a mixture of phomopsene and a biosynthetically linked new compound, allokutznerene, as well as spiroviolene. Both enzymes were subjected to in‐depth mechanistic studies involving isotopic labelling experiments, metal‐cofactor variation, and site‐directed mutagenesis. Oxidation products of phomopsene and allokutznerene are also discussed.
Synthesis and properties of phthalonitrile terminated polyaryl ether nitrile containing fluorene group
Authors: Wang Guangxing , Guo Ying , Li Zheng , Xu Shuangshuang , Han Yue , Luo Zhenhua , Ye Li , Zhou Heng , Zhao Tong
Published: May 2018

A series of phthalonitrile terminated polyaryl ether nitrile oligomers containing fluorene group (BPPENs) were synthesized and cured in the presence of bis[4‐(4‐aminophenoxy)phenyl]sulfone. Additionally, the quartz fiber reinforced composites were prepared by hot‐pressing process. The structure of oligomers was characterized by 1H‐NMR and GPC. The curing behavior of BPPENs was studied by DSC, IR, and rheological tests in detail. Thermal stability and mechanical properties were also investigated. The results showed that the oligomers showed excellent solubility. BPPENs could be dissolved in common solvents at ambient temperature. TGA and DMA results showed that the cured polymer and composites possessed excellent thermal properties with high residual weight of 72.4% at 1000 °C and 5% thermal degradation temperature (T5%) of 548 °C under inert atmosphere. The bending strength of quartz fiber reinforced composites was about 500 MPa, exhibiting good mechanical property. The products could be used as high performance polymers or a modifier for heat‐resistant resins. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46606.
Development and characterization of collagen/gelatin films and gels incorporated with pequi oil
Authors: Horn Marilia M. , Martins Virginia C. A. , Fernandes Yasmin O. M. , Vulcani Valcinir A. S. , Plepis Ana Maria G.
Published: May 2018

Natural compounds, such as pequi oil, could be added to collagen/gelatin mixtures to improve its properties. Gels characterized by rheological analysis indicated modifications in entanglement network of the mixtures after pequi oil addition. Films processed by casting were analyzed by mechanical and thermal properties, contact angle, and scanning electron microscopy (SEM). The pequi oil addition reduced the contact angle values due to the addition of carboxyl groups found in the palmitic and oleic acid chains of pequi oil. The rough characteristic observed by SEM images was a result of a good homogenization process after oil incorporation. In addition, pequi oil addition decreased the tensile forces and elongation of the films and increased the thermal stability possibly due to lower inter‐ and intra‐molecules interactions. The results suggested a good compatibility between pequi oil and biopolymers and the potential application of this natural compound to increase the wound healing process. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46627.
Antiarthritic Effects of Sorafenib in Rats with Adjuvant‐Induced Arthritis
Authors: Wang Zhen‐Zhen , Liu Fei , Gong Yong‐Fang , Huang Tian‐Yu , Zhang Xiao‐Ming , Huang Xue‐Ying
Published: May 2018

Rheumatoid arthritis (RA) is a chronic inflammatory disease affecting the synovial membrane of joints. In this study, we aimed to investigate whether sorafenib exerts antiarthritic effects on RA in vivo. Adjuvant arthritis (AA) was induced (day 0) in male Sprague–Dawley rats by intradermal injection of 0.1 mL of complete Freund's complete adjuvant into the left hind paw. Sorafenib (10, 20, or 40 mg/kg/day) was administered intragastrically from day 10 to 24. Body weight, paw volume, synovial inflammation, and tumor necrosis factor alpha (TNF‐α), interleukin‐1β (IL‐1β), IL‐10, and IL‐17 serum levels were detected. In addition, microvascular density (MVD) and the expression of vascular endothelial growth factor receptor 2 (VEGFR‐2) and fibroblast growth factor receptor 1 (FGFR‐1) in synovial tissues were analyzed. Our data revealed that sorafenib administration led to significant body weight gain in AA rats but suppressed paw swelling, synovial hyperplasia, and inflammatory infiltration. Furthermore, it decreased TNF‐α, IL‐1β, and IL‐17 serum levels and upregulated IL‐10. MVD and VEGFR‐2 and FGFR‐1 expression in synovial tissues were significantly reduced. Thus, this study shows that sorafenib exerts anti‐arthritic effects in AA rats and therefore has potential in RA treatment. Anat Rec, 301:1519–1526, 2018. © 2018 Wiley Periodicals, Inc.
Design of Single‐Site Photocatalysts by Using Metal–Organic Frameworks as a Matrix
Authors: Wen Meicheng , Mori Kohsuke , Kuwahara Yasutaka , An Taicheng , Yamashita Hiromi
Published: May 2018

Single‐site photocatalysts generally display excellent photocatalytic activity and considerably high stability compared with homogeneous catalytic systems. A rational structural design of single‐site photocatalysts with isolated, uniform, and spatially separated active sites in a given solid is of prime importance to achieve high photocatalytic activity. Intense attention has been focused on the design and fabrication of single‐site photocatalysts by using porous materials as a platform. Metal–organic frameworks (MOFs) have great potential in the design and fabrication of single‐site photocatalysts due to their remarkable porosity, ultrahigh surface area, extraordinary tailorability, and significant diversity. MOFs can provide an abundant number of binding sites to anchor active sites, which results in a significant enhancement in photocatalytic performance. In this focus review, the development of single‐site MOF photocatalysts that perform important and challenging chemical redox reactions, such as photocatalytic H2 production, photocatalytic CO2 conversion, and organic transformations, is summarized thoroughly. Successful strategies for the construction of single‐site MOF photocatalysts are summarized and major challenges in their practical applications are noted.
Honeycomb‐Patterned Polyimide Film as a Versatile Coating for High‐Performance Dielectric Material
Authors: Ma Yingyi , Xu Le , Wu Zijian , Zhang Wenlong , Zhang Mingyan , He Zhenfeng
Published: May 2018

A honeycomb‐patterned porous film was conveniently prepared by means of the microemulsion method and then used as an effective coating for improving the dielectric properties and water resistance of polyimide (PI) film while maintaining its mechanical properties. The dielectric properties could be regulated by tuning the structure of the porous film through controlling its formation conditions. When suitable conditions were used, the prepared composite PI film exhibited a significant reduction of 28.3 % in its dielectric constant and 9.48–54.99 % in dielectric loss accompanied by an extremely low water uptake of 0.62 % relative to the 2.47 % of flat PI film. The composite PI film also displayed excellent durability under moist conditions, as the dielectric constant was still below 2.4 after exposure to 75 % relative humidity for more than 12 h. This provides a novel method to improve and control the dielectric properties of materials. It also suggests that this film is a suitable candidate for coating dielectric materials in high‐humidity environments.
Verankerungsverhalten textiler Bewehrungen in dünnen Betonbauteilen
Authors: Bielak Jan , Spelter Arne , Will Norbert , Claßen Martin
Published: May 2018

Die Frage der sicheren und sinnvollen Verankerung von textiler Bewehrung im Beton beschäftigt nicht nur Anwender des innovativen Verbundwerkstoffs Carbonbeton. Auch in der Forschung sind für die Thematik des Verbunds und der Verankerung wesentliche Fragen nicht abschließend geklärt. Bisher existiert kein Bemessungsmodell für die Verankerung oder Übergreifung, welches bei der derzeit verfügbaren Bandbreite textiler Bewehrungen mit weicher bis steifer Tränkung gleichermaßen gültig ist. Die unterschiedlichen Versagensmechanismen des Verbunds, die aus den Charakteristika der Materialien resultieren, werden selten klar unterschieden. Dieser Artikel verdeutlicht die Auswirkungen des Formschlusses auf das Verankerungsverhalten am Beispiel einer textilen Bewehrung mit steifer Tränkung und ordnet Ergebnisse von experimentellen Untersuchungen in die bisherige Forschung ein. Hierzu wird ein Prüfaufbau für einen Auszugversuch vorgestellt, welcher auch zur Abschätzung des Verankerungsverhaltens in Praxisprojekten und zur Qualitätskontrolle in der Produktion genutzt werden kann.
A Designed Enzyme Promotes Selective Post‐translational Acylation
Authors: Gosavi Pallavi M. , Jayachandran Megha , Rempillo Joel J. L. , Zozulia Oleksii , Makhlynets Olga V. , Korendovych Ivan V.
Published: May 2018

A computationally designed, allosterically regulated catalyst (CaM M144H) produced by substituting a single residue in calmodulin, a non‐enzymatic protein, is capable of efficient and site selective post‐translational acylation of lysines in peptides with highly diverse sequences. Calmodulin′s binding partners are involved in regulating a large number of cellular processes; this new chemical‐biology tool will help to identify them and provide structural insight into their interactions with calmodulin.
Synthesis of Azo Dyes from Mesoionic Carbenes and Nitrous Oxide
Authors: Eymann Léonard Y. M. , Scopelliti Rosario , Tirani Farzaneh Fadaei , Severin Kay
Published: May 2018

Covalent adducts of imidazole‐based mesoionic carbenes and nitrous oxide (N2O, “laughing gas”) can be converted into azo dyes by reaction with arenes in the presence of AlCl3 or HCl. The azo coupling can be achieved with electron‐rich aromatic compounds such as mesitylene, trimethoxybenzene, azulene, or dibenzo‐18‐crown‐6. The latter coupling reaction allows for the easy preparation of a colorimetric sensor for potassium or sodium ions. As a putative intermediate of the reaction with acid, we were able to isolate and structurally characterize a rare diazohydroxide. Using imidazolium compounds with two N2O groups, it was possible to prepare amine‐substituted azo dyes or dyes with two azoarene groups attached to the heterocycle. A triazole‐based mesoionic carbene was also found to form a stable covalent adduct with N2O. The adduct could be used to prepare novel azo triazolium dyes in good yields.
Small molecule targeting of the actin associating protein tropomyosin Tpm3.1 increases neuroblastoma cell response to inhibition of Rac‐mediated multicellular invasion
Authors: Mitchell Camilla B. , Stehn Justine R. , O'Neill Geraldine M.
Published: May 2018

The migration and invasion of cells through tissues in the body is facilitated by a dynamic actin cytoskeleton. The actin‐associating protein, tropomyosin Tpm3.1 has emerged to play important roles in cell migration and invasion. To date, investigations have focused on single cell migration and invasion where Tpm3.1 expression is inversely associated with Rac GTPase‐mediated cell invasion. While single cell and collective cell invasion have many features in common, collective invasion is additionally impacted by cell–cell adhesion, and the role of Tpm3.1 in collective invasion has not been established. In the present study we have modelled multicellular invasion using neuroblastoma spheroids embedded in 3D collagen and analysed the function of Tpm3.1 using recently established compounds that target the Tpm3.1 C‐terminus. The major findings from our study reveal that combined Rac inhibition and Tpm3.1 targeting result in greater inhibition of multicellular invasion than either treatment alone. Together, the data suggest that Tpm3.1 disruption sensitises neuroblastoma cells to inhibition of Rac‐mediated multicellular invasion.
Multispectral Live‐Cell Imaging
Authors: Cohen Sarah , Valm Alex M. , Lippincott‐Schwartz Jennifer
Published: May 2018

Fluorescent proteins and vital dyes are invaluable tools for studying dynamic processes within living cells. However, the ability to distinguish more than a few different fluorescent reporters in a single sample is limited by the spectral overlap of available fluorophores. Here, we present a protocol for imaging live cells labeled with six fluorophores simultaneously. A confocal microscope with a spectral detector is used to acquire images, and linear unmixing algorithms are applied to identify the fluorophores present in each pixel of the image. We describe the application of this method to visualize the dynamics of six different organelles, and to quantify the contacts between organelles. However, this method can be used to image any molecule amenable to tagging with a fluorescent probe. Thus, multispectral live‐cell imaging is a powerful tool for systems‐level analysis of cellular organization and dynamics. © 2018 by John Wiley & Sons, Inc.
Common Polymorphisms of CYP2B6 Influence Stereoselective Bupropion Disposition
Authors: Kharasch Evan D. , Crafford Amanda
Published: May 2018

Bupropion hydroxylation is a bioactivation and metabolic pathway, and the standard clinical CYP2B6 probe. This investigation determined the influence of CYP2B6 allelic variants on clinical concentrations and metabolism of bupropion enantiomers. Secondary objectives evaluated the influence of CYP2C19 and P450 oxidoreductase variants. Healthy volunteers in specific cohorts (CYP2B6*1/*1, CYP2B6*1/*6, CYP2B6*6/*6, and also CYP2B6*4 carriers) received single‐dose oral bupropion. Plasma and urine bupropion and hydroxybupropion was quantified. Subjects were also genotyped for CYP2C19 and P450 oxidoreductase variants. Hydroxylation of both bupropion enantiomers, assessed by plasma hydroxybupropion/bupropion AUC ratios and urine hydroxybupropion formation clearances, was lower in CYP2B6*6/*6 but not CYP2B6*1/*6 compared with CYP2B6*1/*1 genotypes, and numerically greater in CYP2B6*4 carriers. CYP2C19 and P450 oxidoreductase variants did not influence bupropion enantiomers hydroxylation or plasma concentrations. The results show that clinical hydroxylation of both bupropion enantiomers was equivalently influenced by CYP2B6 allelic variation. CYP2B6 polymorphisms affect S‐bupropion bioactivation, which may affect therapeutic outcomes.
Reactivity of Cp*Al towards Silanols: Formation and Hydrolysis of Alumosiloxanes
Authors: Wittwer Philipp , Stelzer Adrian , Braun Thomas
Published: May 2018

Treatment of [Cp*Al]4 (1) (Cp* = pentamethylcyclopentadienyl) with various silanols gave access to the compounds [Al{OSi(OtBu)3}3(DMAP)] (3) (DMAP = 4‐dimethylaminopyridine), [HNEt3][Al(OSiPh3)4] (4), and [Al7(OH)9{(OSiiPr2)2O}6] (6). ESI mass spectrometry revealed that 6 exchanges its outer hydroxyl groups in the presence of H218O water. Hydrolysis of 4 led to the formation of [HNEt3][Al(OH)(OSiPh3)3] (5), but only in the presence of additional NEt3. The structures in the solid state of 6·toluene, 6·(THF)3, 6·(H2O·2THF)3, and 5 were determined by X‐ray crystallography.
Exploring attentional biases towards facial expressions of pain in men and women
Authors: Keogh E. , Cheng F. , Wang S.
Published: May 2018

Background

Interpersonal factors may help explain why men and women differ in their perception and expression of pain. Whilst the focus is often on the person in pain, how observers respond to those in pain is important. This study explored whether male–female differences exist in the way observers attend to expressions of pain in others.

Methods

Fifty‐three adults (26 females) completed a visual dot‐probe task, to measure selective attentional biases to facial expressions of pain and fear. Expression pairs (e.g. pain/neutral) were displayed by either the same male or female actor, and in two different viewing duration conditions: 150 and 1250 ms. Dot‐probes appeared in either a congruent or incongruent location to the target expression.

Results

No evidence was found for sex‐related attentional biases towards pain or fear. However, when examining congruency and incongruency indexes separately, differences emerged. The congruency index analysis indicated that in the 150‐ms presentation condition, both men and women were slower during congruent female pain/neutral trials when compared to neutral/neutral trials, and relatively faster at responding during congruent male pain/neutral trials.

Conclusions

There is utility in exploring the attentional processes involved in the decoding of pain‐related expressions to understand the influence of sex and gender differences in pain. Although male–female differences were found, this was most clearly related to the actor. Our results point to an early attentional mechanism that orients attention away from female expressions of pain. Future consideration of sex‐ and gender‐related contextual factors in attentional processing is warranted.

Significance

Sex‐related factors seem to affect how observers view the pain of others. Our results point to an early attentional mechanism that orients the attention of observers away from female expressions of pain.