bluuebunny/crossref_metadata_2025_split huggingface dataset:
O PROFESSOR E O MÉTODO: PAPÉIS, DIÁLOGOS E DILEMAS (The teacher and the method: roles, dialogues and dilemmas)
Authors: Amarante José 
Published: January 2019

<p>A imprecisão terminológica na área de ensino de línguas estrangeiras tem levado, desde a década de 60, à proposição de uma definição terminológica, cujo consenso, a nosso ver, está ainda em processo de negociação. Da obsessão pela busca do <em>método perfeito</em>, a partir da segunda metade do século XX, à constatação - do final da década de 90 até nossos dias - da impossibilidade de sucesso nessa busca e à definição de um <em>ecletismo </em>na formatação pedagógica, o terreno é ainda espinhoso. Merecem destaque nesse processo de definição conceitual as propostas de Anthony (1963) e de Richards &amp; Rodgers (1986), com as quais queremos dialogar. Além disso, pretendemos discutir, a partir das dimensões da profissão docente, alguns aspectos: os papéis do professor na sua relação com métodos, as delicadezas conceituais do chamado ecletismo pedagógico, os diálogos possíveis entre as concepções do professor e as concepções implícitas ou explícitas dos materiais didáticos, e os dilemas decorrentes desse processo de “negociação”. Sua discussão desemboca na análise desses aspectos conceituais no contexto do ensino do latim, quando o autor defende, no papel do professor em relação ao uso de “métodos”, uma atitude de coautoria de materiais para o ensino.</p>
Dopamine compartmentalization, selective dopaminergic vulnerabilities in Parkinson's disease and therapeutic opportunities
Authors: Uhl George R. 
Published: January 2019

AbstractProgressive depletion of selected dopamine neurons is central to much Parkinson's disease (PD) disability. Although symptomatic treatments can ameliorate the disabilities that this neuronal depletion causes, no current strategy is documented to slow these losses. There is substantial evidence that dopamine in intracytoplasmic/extravesicular neuronal compartments can be toxic. Here, I review evidence that supports roles for dopamine compartmentalization, mediated largely by serial actions of plasma membrane SLC6A3/DAT and vesicular SLC18A2/VMAT2 transporters, in the selective patterns of dopamine neuronal loss found in PD brains. This compartmentalization hypothesis for the dopamine cell type specificity of PD lesions nominates available drugs for amelioration of damage arising from miscompartmentalized dopamine and raises cautions in using other drugs.
Passivity‐based adaptive control of a 2‐DOF serial robot manipulator with temperature dependent joint frictions
Authors: Azizi Yaghoub , Yazdizadeh Alireza 
Published: January 2019

SummaryMechanical systems are always suffering from the effects of temperature dependent friction forces where the system is operated in a wide range of temperature. Temperature and its variation play an important role in friction force in mechanical systems. If it is not compensated, it will tend to unwanted consequences, including steady‐state errors, limit cycling, and hunting. Therefore, it is necessary to take the temperature effects into account. This has been a strong motivation for the researchers to work on temperature effects on joint friction. In this paper, an adaptive compensation (control) scheme is proposed and applied to a 2‐degree‐of‐freedom serial robot manipulator by taking the temperature effects into account on the joints friction. In the proposed control scheme, the temperature is not required to be sensed. In this paper, joint friction is described by LuGre dynamic model with temperature dependent parameters. These parameters are described by some functions with unknown temperature dependent terms. According to the mathematical and practical concepts, the temperature dependent friction is decomposed into a viscous term and a disturbance term. An adaptive controller is designed to compensate the friction effect and it is shown that the proposed controller relaxes the condition for a priori knowledge about the environment characteristics, including the upper and lower bounds of the environment temperature and the parameters of the functions, describing the temperature dependent joint frictions. The stability and convergence of the joint position and velocity are proved in the sense of Lyapunov and then the proposed method is confirmed by the simulations.
Transparent, Flexible, Penetrating Microelectrode Arrays with Capabilities of Single‐Unit Electrophysiology
Authors: Seo Kyung Jin , Artoni Pietro , Qiang Yi , Zhong Yiding , Han Xun , Shi Zhan , Yao Wenhao , Fagiolini Michela , Fang Hui 
Published: January 2019

AbstractAccurately mapping neuronal activity across brain networks is critical to understand behaviors, yet it is very challenging due to the need of tools with both high spatial and temporal resolutions. Here, penetrating arrays of flexible microelectrodes made of low‐impedance nanomeshes are presented, which are capable of recording single‐unit electrophysiological neuronal activity and at the same time, transparent, allowing to bridge electrical and optical brain mapping modalities. These 32 transparent penetrating electrodes with site area, 225 µm2, have a low impedance of ≈149 kΩ at 1 kHz, an adequate charge injection limit of ≈0.76 mC cm−2, and up to 100% yield. Mechanical bending tests reveal that the array is robust up to 1000 bending cycles, and its high transmittance of 67% at 550 nm makes it suitable for combining with various optical methods. A temporary stiffening using polyethylene glycol allows the penetrating nanomesh arrays to be inserted into the brain minimally invasively, with in vivo validation of recordings of spontaneous and evoked single‐unit activity of neurons across layers of the mouse visual cortex. Together, these results establish a novel neurotechnology—transparent, flexible, penetrating microelectrode arrays—which possesses great potential for brain research.
Fabrication of Ultrathin 2D Cu‐BDC Nanosheets and the Derived Integrated MOF Nanocomposites
Authors: Zhan Guowu , Fan Longlong , Zhao Feigang , Huang Zhongliang , Chen Bin , Yang Xin , Zhou Shu‐feng 
Published: January 2019

AbstractFreestanding 2D nanosheets with many unprecedented properties have been used in a myriad of applications. In this work, 2D copper‐bearing metal‐organic frameworks (MOFs; viz., Cu‐BDC) nanosheets are successfully fabricated via a facile and benign methodology through using Cu2O nanocubes (≈60 nm) as a confined metal ion source and 1,4‐benzenedicarboxylic acid (H2BDC) as an organic linker. The Cu2O nanocubes gradually release Cu+ ions which are further oxidized by the dissolved oxygen and serve as nutrients for construction of 2D frameworks. In contrast, the conventional solvothermal synthesis with copper salt exclusively yields bulk Cu‐BDC with edge dimensions of 2–10 µm. Interestingly, the as‐prepared Cu‐BDC nanosheets show ultrathin thickness, oriented growth, and excellent crystallinity, which can be exploited as a platform for the design of a series of 2D‐integrated nanocatalysts by loading various metal nanocrystals such as Au, Ag, Pt, and Ru, with 3‐mercaptopropionic acid as molecular link. In addition, it is found that Cu‐BDC/M composites with highly accessible active sites on the surface exhibit high catalytic activity in several condensation reactions between benzaldehyde and primary amines. The findings offer an alternative strategy for rational design and synthesis of 2D MOF nanosheets and the derived 2D nanocomposites for catalytic applications.
From Atoms to Lives: The Evolution of Nanoparticle Assemblies
Authors: Xue Zhenjie , Yan Cong , Wang Tie 
Published: January 2019

AbstractNanoparticle (NP) assemblies have been studied over the past several decades, and the field is advancing more quickly and reaching into more diverse fields. Reports issued from academic and industrial laboratories have driven these advances. Countless breakthroughs have been reported in widely different fields, including thermoelectronics, photoelectronics, catalysts, energy sources, and medical carriers. A “family tree” is clearly needed to accurately trace the developments in the study of NP assemblies. This review uses the unconventional approach of comparing the atomic and NP worlds to describe the development of NP research during the past several decades. The corresponding classifications, such as atoms and NPs, molecules and molecular‐type NP assemblies, crystals and crystalline‐type NP assemblies, biological organisms and analogous artificial assemblies, and biologically functional NP complex assemblies, are discussed in detail. It concludes with remarks concerning the trend from nonliving to living applications of NP assemblies.
Metamorphic Stretchable Touchpad
Authors: Biswas Shantonu , Reiprich Johannes , Pezoldt Joerg , Stauden Thomas , Jacobs Heiko O. 
Published: January 2019

AbstractConventional touchpads are an example of a common human–machine interface. They are rigid devices with a limited usability without any form of adaptability and conformity to different morphologies necessary for gaming and virtual reality applications. A metamorphic touchpad is an envisioned conceptual approach of shape changing electronics. To demonstrate this, a multipurpose touchpad able to serve as a flexible, 2D stretchable, and 3D metamorphic device is designed and fabricated. The approach replaces the rigid carrier and rigid interconnects by mechanically stretchable structures. The metamorphic touchpad can be wrapped around 3D shapes or undergo reversible topological changes from a conventional planar to a hemispheric shape.
Self‐Assembly of Colloidal Spheres toward Fabrication of Hierarchical and Periodic Nanostructures for Technological Applications
Authors: Liang Xiaoguang , Dong Ruoting , Ho Johnny C. 
Published: January 2019

AbstractThe current research status on the self‐assembly of colloidal spheres for the fabrication of various hierarchical and periodic nanostructures is summarized, in which these structures exhibit unique properties for different technological applications in plasmonics, surface‐enhanced Raman scattering, solar cells, and others. The fundamentals of colloidal self‐assembly are first introduced. After which, the functions of the obtained monolayer of colloidal spheres (e.g., nanosphere monolayer) to act as the patterned mask for the subsequent pattern transfer onto underlying substrates are thoroughly discussed. In employing these nanosphere lithography techniques and fabrication templates, the focus switches to the successive construction of numerous nanostructures and their promising utilizations in a wide range of application domains. Finally, the current challenges and future opportunities of colloidal self‐assembly are presented. This review not only aims to provide further insights for researchers to enable the ingenious designs of nanostructures, but also to facilitate the exciting research and development utilizing colloidal self‐assembly for future manufacturing technologies.
Engineering Tunable Broadband Near‐Infrared Emission in Transparent Rare‐Earth Doped Nanocrystals‐in‐Glass Composites via a Bottom‐Up Strategy
Authors: Pan Qiwen , Cai Zhenlu , Yang Yerong , Yang Dandan , Kang Shiliang , Chen Zhi , Qiu Jianrong , Zhan Qiuqiang , Dong Guoping 
Published: January 2019

AbstractApplications of trivalent rare earth (RE3+)‐doped light sources in solid‐state laser technology, optical communications, biolabeling, and solar energy management have stimulated a growing demand for broadband emission with flexible tunability and high efficiency. Codoping is a conventional strategy for manipulating the photoluminescence of active RE3+ ions. However, energy transfer between sensitizers and activators usually induces nonradiative migration depletion that brings detrimental luminescent quenching. Here, a transparent framework is employed to assemble ordered RE3+‐doped emitters to extend the emission spectral range by extracting photons from a variety of RE3+ ions with sequential energy gradient. To block migration‐mediated depletion between different RE3+ ions, a nanoscopic heterogeneous architecture is constructed to spatially confine the RE3+ clusters via a “nanocrystals‐in‐glass composite” (NGC) structure. This bottom‐up strategy endows the obtained RE3+‐doped NGC with high emission intensity (nearly one order of magnitude enhancement) and broadband near‐infrared emission from 1300 to 1600 nm, which covers nearly the whole low‐loss optical communication window. Most crucially, NGC is a versatile approach to design tunable broadband emission for the potential applications in high‐performance photonic devices, which also provides new opportunities for engineering multifunctional materials by integration and manipulation of diverse functional building units in a nanoscopic region.
Gold‐catalyzed Rapid Construction of Nitrogen‐containing Heterocyclic Compound Library with Scaffold Diversity and Molecular Complexity
Authors: Qiao Jin , Jia Xiuwen , Li Pinyi , Liu Xiaoyan , Zhao Jingwei , Zhou Yu , Wang Jiang , Liu Hong , Zhao Fei 
Published: January 2019

Abstract1,3‐unsubstituted 2‐(1H‐indol‐2‐yl)ethanamines were employed for the first time to react with alkynoic acids (AAs) to achieve gold‐catalyzed highly selective cascade reactions to furnish novel indole‐fused skeletons. Furthermore, with this powerful gold catalytic system, a library of indole/pyrrole/thiophene/benzene/naphthalene/pyridine‐based nitrogen‐containing heterocyclic compounds (NCHCs) with scaffold diversity and molecular complexity was constructed rapidly using various amine nucleophiles (ANs) and diverse AAs as the building blocks. This general protocol features excellent selectivity, extraordinarily broad substrate scope, readily available inputs, good to high yields, high bond‐forming efficiency, and step economy, thus providing a facile and efficient access to a variety of valuable nitrogen‐containing heterocycles.magnified image
Selective C−H or N−H Imidoylative Annulation of 2‐(2‐Isocyanophenyl)‐1H‐indoles Leading to Diverse Indole‐fused Scaffolds
Authors: Teng Fan , Hu Weiming , Hu Huaanzi , Luo Shuang , Zhu Qiang 
Published: January 2019

Abstract2‐(2‐Isocyanophenyl)‐1H‐indoles, a class of functionalized isocyanides containing both aromatic C−H and indolo N−H functionalities, are first applied in selective imidoylative annulation reactions. Scaffolds of 6‐aryl 11H‐indolo[3,2‐c]quinoline and 6‐aryl indolo[1,2‐c]quinazoline, both of which are of biological importance, are obtained selectively through capturing the imidoyl radical or imidoyl palladium intermediates by the C−H and N−H bonds, respectively.magnified image
Metal‐Free Oxidation of Trichloroacetimidates to Aldehydes
Authors: Lou Ji‐Cong , Li Jian‐Ye , Sun Wen‐Wu , Wu Bin 
Published: January 2019

AbstractA metal‐free oxidation reaction of trichloroacetimidates to aldehydes or ketones with DMSO as an oxidant is reported. The reaction exhibits a broad range of functional group tolerance. Detailed mechanistic studies were performed with the aid of NMR, in situ IR spectroscopy, GC‐MS analysis and 18O‐labeling experiments.
Das Zusammenspiel zwischen Wasserstoffbrücken und Präorganisation in der Entwicklung von selbstassemblierenden Systemen
Authors: Philips Divya S. , Kartha Kalathil K. , Politi Antiope T. , Krüger Timo , Albuquerque Rodrigo Q. , Fernández Gustavo 
Published: January 2019

AbstractKooperative π‐π‐Wechselwirkungen und Wasserstoffbrückenbindungen werden häufig in supramolekularen Polymerisationen genutzt. Nähere Untersuchungen zu deren Zusammenspiel wurden in der Vergangenheit jedoch weitestgehend vernachlässigt. In dieser Arbeit wird das Aggregationsverhalten einer Reihe von C2‐ und C3‐ symmetrischen Oligophenylenethinylenen, die sich in der Topologie des Amids (N‐ oder C‐zentriert) unterscheiden, verglichen. Diese geringe strukturelle Veränderung bewirkt drastische Unterschiede in den photophysikalischen und supramolekularen Eigenschaften. Somit wird der gegenseitige Einfluss von Wasserstoffbrückenbindungen und geometrischer Präorganisation auf den Assemblierungsprozess und dessen Endresultat in supramolekularen Systemen hervorgehoben.
Effects of the γ‐irradiation strength and basalt additive content on the mechanical performance and dielectric response of polypropylene films
Authors: Kılıç Mehmet , Özdemir Zeynep Güven , Alkan Ümit , Karabul Yaşar , İçelli Orhan 
Published: January 2019

ABSTRACTIn this study, we investigated the effects of high‐dose γ‐ray irradiation on the mechanical and dielectric properties of polypropylene (PP)–basalt thick films. PP–basalt thick‐film composites with various basalt contents from 0.5 to 10.0% were prepared by a hot‐press method. The samples were exposed to γ radiation at different doses in the range 3–25 kGy. The mechanical properties of the samples, such as the Young's modulus, tensile strength, percentage strain at break, and energy at break, were examined in the context of the γ‐irradiation process. Although the maximum elasticity was obtained for the unirradiated 0.5% basalt‐added composite, the 6 kGy γ‐irradiated PP–1.0% basalt sample exhibited the highest elasticity properties among all of the composites. The best mechanical properties, including the ultimate tensile strength and energy at break values, were achieved for the 12 kGy γ‐irradiated neat PP. The dielectric properties of the PP–basalt composites were also investigated in the 100 Hz to 15 MHz frequency region at room temperature. According to the analysis of the dielectric properties, the 3 kGy γ‐irradiated neat PP may have potential for microelectronic device applications that require low dielectric constant and dielectric loss materials. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47414.
Effects of montmorillonite on structures and properties of injection‐molded polypropylene
Authors: Zhang Chunbo , Ma Yi , Feng Bo , Han Zhihua , Zhang Zhicheng , Liang Wenbin , Wang Ke 
Published: January 2019

ABSTRACTA nanocomposite of polypropylene with montmorillonite (PP‐MMT) was prepared via melt blending. The structures and properties of PP‐MMT were studied by differential scanning calorimetry, polarized optical microscopy, transmission electron microscopy (TEM), and wide‐angle X‐ray diffraction (WAXD). The orientation behaviors of both MMT and PP in an injection‐molded specimen were revealed by TEM and WAXD. The results indicate that the specimen displays a multilayer structure: in the inner layer, the long axes of MMT stacks are parallel to the transverse direction (TD) of the specimen and the b‐axes of PP crystallites are perpendicular to the TD; whereas in the outer layer, the long axes of MMT are perpendicular to the TD and the b‐axes of PP crystallites are parallel to the TD. The orientation of PP crystallites in PP‐MMT is much lower than that in pure PP, which results in lower molding shrinkage of PP‐MMT. Structure–property relationship of PP‐MMT was discussed with a conclusion that a moderate improvement in performances of PP‐MMT might be derived from the intercalated dispersion and special orientation of MMT stacks. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47442.
Dielectric property of modified barium titanate/polyamide 11 nanocomposites with different surfactants
Authors: Li WenMin , Chen Minzhang , Yang YunYun , Yuan Dandan , Ren Ying , Cai Xufu 
Published: January 2019

ABSTRACTBarium titanate/polyamide 11 (BT/PA11) nanocomposites were prepared by modifying BT nanoparticles with dry surface modification process, which had well dispersion, high dielectric constant, and low dielectric loss. Various methods were reported to improve dispersion and compatibility with complex process and high cost. Herein, three surfactants [
γ‐aminopropyl triethoxy silane (KH550), sorbitan monostearate (SP60), and octadecyl phosphate ester (OPE)] were chosen to modify BT nanoparticles. Then modified‐BT nanoparticles were blended with PA11. The structure was characterized by Fourier transform infrared, scanning electron microscope, and wide angle X‐ray diffraction. Dielectric property was studied by broadband dielectric spectroscopy. The frequency dependence and temperature dependence of dielectric constant, dielectric loss, and dielectric modulus were analyzed. In general, dielectric property has strong frequency and temperature dependence. Furthermore, dielectric spectra shows that modified BT/PA11 nanocomposites have higher dielectric constant, lower dielectric loss, fewer interface polarization, and more dipole polarization. In contrast to three surfactants, OPE‐BT nanoparticles have better effects, whose dielectric constant increases from 19 to 28 at 1 Hz, and dielectric loss decreases from 0.36 to 0.23. Meanwhile, mechanical property was characterized by universal testing machine. In all, the work improves dispersion of BT nanoparticles and dielectric property with easy process and low cost. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47447.
Bio‐based polyurethane films using white dextrins
Authors: Konieczny Jakob , Loos Katja 
Published: January 2019

ABSTRACTSeveral new eco‐friendly materials have the potential to replace conventional petroleum‐derived materials and monomers. Among them are natural polysaccharides. The use of polysaccharides in polyurethane (PU) synthesis has not yet been studied extensively, even though as multihydroxyl compounds, they can easily serve as crosslinkers in PU synthesis. One naturally occurring (hyper‐)branched polymer is amylopectin, a component of starch. In this work, we report the PU synthesis and film‐forming capacity using the asymmetric cyclic aliphatic diisocyanate—isophorone diisocyanate (IPDI) with acetylated and pristine partially hydrolyzed amylopectin/white dextrin (AVEDEX W80) as a crosslinker. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47454.
Reinforcing effect of amine‐functionalized and carboxylated porous graphene on toughness, thermal stability, and electrical conductivity of epoxy‐based nanocomposites
Authors: Naderi Mehdi , Ebrahimi Farnaz , Najafi Mohammad , Naderi Hamed 
Published: January 2019

ABSTRACTEpoxy‐based nanocomposites reinforced with nonfunctionalized porous graphene (NPG), carboxylated porous graphene (CNPG), and amine‐functionalized porous graphene (ANPG) were investigated with regard to mechanical properties, thermal stability, and electrical conductivity. Nanomaterials were added to the epoxy matrix in varying contents of 0.5, 1, and 2 wt %. Generally, mechanical properties were improved as a result of introducing nanomaterials into the epoxy resin. However, the amelioration of toughness was only observed in functionalized NPGs/epoxy nanocomposites. Field emission scanning electron microscopy images showed that functionalized nanomaterials induced a rougher fracture surface compared to the neat epoxy. Dynamic mechanical analysis along with differential scanning calorimetry confirmed an increment in the glass‐transition temperature (Tg) of the reinforced nanocomposites. Also, they proved that functionalization made the epoxy network tougher and more flexible. The electrical conductivity and thermal stability of the epoxy resin were also improved when loaded with nanomaterials. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47475.