Although a great deal of literature contrasts the Chinese learner with Western learning conceptions and practice, a closer look at these studies reveals that many are explored through the lens of ...cultural knowledge and assumptions. The results of these studies generate a distorted understanding of Chinese students. Moreover, students' learning is best explained in the context of local environments. This study therefore examines the "Chinese learner" through a case study of mainland Chinese postgraduate students' intercultural learning experiences at British universities. The results show that learning beliefs and behaviors evolve as individuals participate in authentic situations. It is essential to break the stereotypes of Chinese students and constantly document the progress of their learning so as to generate effective intercultural pedagogy and practices in culturally diverse classrooms. Further, how Chinese students approach their learning is a complex phenomenon with multiple facets interacting including external factors, namely sociohistorical, cultural, and academic contexts, and internal factors, such as each student's intellectual development. Academic staff in multicultural classrooms should recognize not just similarities but also diversity of students from the same culture and amend their teaching practices in response to students' developing needs and interests (HRK / Abstract übernommen).
Exfoliating montmorillonite (Mt) to nanolayers is a crucial step during producing clay/polymer nanocomposites(CPN). Only well-exfoliated and well-dispersed Mt. nanolayers in the polymer matrix can ...significantly improve the properties of the nanocomposites. This review examines the latest scientific advances in the exfoliation methods of Mt., the insights into the exfoliation mechanisms, and the peculiar functionalities of the resultant CPN. The direct exfoliation of Mt. dispersed in water or organic solvents is often intensified by ultrasonication. Grinding of Mt. in the form of solid in a high-energy ball mill can directly exfoliate Mt. to some extent. Exfoliating Mt. for producing CPN is mainly achieved through so-called in situ exfoliation, solution exfoliation and melt exfoliation. The Mt./polymer nanocomposites exhibit typically improved barrier properties, mechanical strength, thermal stability, and fire retardancy. The literature survey suggests that future work should place emphases on developing green and effective exfoliation methods, and deepening understanding of exfoliation mechanisms and the interfacial interactions between the inorganic Mt. nanolayers and organic monomers/polymers. Future research is suggested to assembling exfoliated Mt. nanolayers with functional polymeric molecules or other nano-scale building blocks to produce functional hierarchical nanomaterials with practical applications.
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•Literature survey and opinions on exfoliating montmorillonite (Mt) into nanolayers.•Organic modification of Mt for exfoliating Mt in polymer matrix.•Exfoliation of Mt by in situ polymerization, in polymer solution, and melt exfoliation•Exfoliated Mt for improving barrier, mechanical and thermal properties, and flame retardancy.•Remarks on challenges and opportunities in exfoliation of Mt for nanocomposites.
Metal–organic frameworks (MOFs) with carboxylate ligands as co‐catalysts are very efficient for the oxygen evolution reaction (OER). However, the role of local adsorbed carboxylate ligands around the ...in‐situ‐transformed metal (oxy)hydroxides during OER is often overlooked. We reveal the extraordinary role and mechanism of surface‐adsorbed carboxylate ligands on bi/trimetallic layered double hydroxides (LDHs)/MOFs for OER electrocatalytic activity enhancement. The results of X‐ray photoelectron spectroscopy (XPS), synchrotron X‐ray absorption spectroscopy, and density functional theory (DFT) calculations show that the carboxylic groups around metal (oxy)hydroxides can efficiently induce interfacial electron redistribution, facilitate an abundant high‐valence state of nickel species with a partially distorted octahedral structure, and optimize the d‐band center together with the beneficial Gibbs free energy of the intermediate. Furthermore, the results of in situ Raman and FTIR spectra reveal that the surface‐adsorbed carboxylate ligands as Lewis base can promote sluggish OER kinetics by accelerating proton transfer and facilitating adsorption, activation, and dissociation of hydroxyl ions (OH−).
In the oxygen evolution reaction (OER), surface‐adsorbed carboxylate ligands on bi/trimetallic layered double hydroxides (LDHs)/MOFs demonstrate a synergistic effect. As a Lewis base the carboxylate ligands promote the sluggish OER by accelerating proton transfer and facilitating adsorption, activation, and dissociation of OH− ions, while also facilitating intrinsic electron redistribution and a partially distorted octahedral structure.
A review of the salinity measurement technology based on the optical fiber sensor is presented. The principles of optical fiber measurement, the structures of probes and the characteristics of ...various sensing structures are concerned. Firstly, this paper discusses the relationship between the salinity and refractive index, and the effect of ion pairs on the refractive index. Secondly, four methods of direct or non-direct measurements of salinity are summarized, including optical refraction method, optical fiber grating, optical interference and surface plasmon effect. Subsequently, the article compares performances of various sensing structures and analyses the advantages and disadvantages of different sensors. Finally, a prospect of salinity measurement requirement and the development direction of fiber-optic sensors in this area are addressed.
A
bstract
In the geometric approach to defining complexity, operator complexity is defined as the distance in the operator space. In this paper, based on the analogy with the circuit complexity, the ...operator size is adopted as the metric of the operator space where the path length is the complexity. The typical sectional curvatures of this complexity geometry are positive. It is further proved that the typical sectional curvatures are always positive if the metric is an arbitrary function of operator size, while complexity geometry is usually expected to be defined on negatively curved manifolds. By analyzing the sectional curvatures distribution for the
N
-qubit system, it is shown that surfaces generated by Hamiltonians of size smaller than the typical size can have negative curvatures. In the large
N
limit, the form of complexity metric is uniquely constrained up to constant corrections if we require sectional curvatures are of order 1
/N
2
. With the knowledge of states, the operator size should be modified due to the redundant action of operators, and thus is generalized to be state-dependent. Then we use this state-dependent operator size as the metric of the Hilbert space to define state complexity. It can also be shown that in the Hilbert space, 2-surfaces generated by operators of size much smaller than the typical size acting on typical states also have negative curvatures.
Dendrite growth of alkali metal anodes limited their lifetime for charge/discharge cycling. Here, we report near-perfect anodes of lithium, sodium, and potassium metals achieved by electrochemical ...polishing, which removes microscopic defects and creates ultra-smooth ultra-thin solid-electrolyte interphase layers at metal surfaces for providing a homogeneous environment. Precise characterizations by AFM force probing with corroborative in-depth XPS profile analysis reveal that the ultra-smooth ultra-thin solid-electrolyte interphase can be designed to have alternating inorganic-rich and organic-rich/mixed multi-layered structure, which offers mechanical property of coupled rigidity and elasticity. The polished metal anodes exhibit significantly enhanced cycling stability, specifically the lithium anodes can cycle for over 200 times at a real current density of 2 mA cm
with 100% depth of discharge. Our work illustrates that an ultra-smooth ultra-thin solid-electrolyte interphase may be robust enough to suppress dendrite growth and thus serve as an initial layer for further improved protection of alkali metal anodes.
Much of the recent progress in Vision-to-Language problems has been achieved through a combination of Convolutional Neural Networks (CNNs) and Recurrent Neural Networks (RNNs). This approach does not ...explicitly represent high-level semantic concepts, but rather seeks to progress directly from image features to text. In this paper we first propose a method of incorporating high-level concepts into the successful CNN-RNN approach, and show that it achieves a significant improvement on the state-of-the-art in both image captioning and visual question answering. We further show that the same mechanism can be used to incorporate external knowledge, which is critically important for answering high level visual questions. Specifically, we design a visual question answering model that combines an internal representation of the content of an image with information extracted from a general knowledge base to answer a broad range of image-based questions. It particularly allows questions to be asked where the image alone does not contain the information required to select the appropriate answer. Our final model achieves the best reported results for both image captioning and visual question answering on several of the major benchmark datasets.
Low-cost transition-metal dichalcogenides (MS2) have attracted great interest as alternative catalysts for hydrogen evolution. However, a significant challenge is the formation of sulfur–hydrogen ...bonds on MS2 (S–Hads), which will severely suppress hydrogen evolution reaction (HER). Here we report Cu nanodots (NDs)-decorated Ni3S2 nanotubes (NTs) supported on carbon fibers (CFs) (Cu NDs/Ni3S2 NTs-CFs) as efficient electrocatalysts for HER in alkaline media. The electronic interactions between Cu and Ni3S2 result in Cu NDs that are positively charged and can promote water adsorption and activation. Meanwhile, Ni3S2 NTs are negatively charged and can weaken S–Hads bonds formed on catalyst surfaces. Therefore, the Cu/Ni3S2 hybrids can optimize H adsorption and desorption on electrocatalysts and can promote both Volmer and Heyrovsky steps of HER. The strong interactions between Cu and Ni3S2 cause the Cu NDs/Ni3S2 NTs-CFs electrocatalysts to exhibit the outstanding HER catalytic performance with low onset potential, high catalytic activity, and excellent stability.
A new sensing method for simultaneous measurement of seawater temperature and salinity by C-type micro-structured fiber was proposed. The C-type fiber structure formed by removing the outer wall of ...one pore from a six holes micro-structured fiber, which would bring in birefringence and broke original pattern of degeneracy. By optimizing the parameters of this fiber structure, X polarization and Y polarization of fundamental mode were separate. Therefore, it could be used for double parameter measurement. Besides, gold film coated on the surface of structure to enhance sensing sensitivity by Surface Plasmon Resonance (SPR) principle. In this study, finite element analysis method was used to analyze the spectral transmission characteristics of C-type micro-structured optical fiber. The surface of wedge-shaped defect was contacted with seawater directly to feel salinity; meanwhile, thermo-optic material filled into pores to detect the temperature of seawater. Through model analysis, it was proved that the proposed filling structure could produce two SPR loss valleys, which had different responses to temperature and salinity. Under optimized structure, maximum salinity sensitivity of 1.402nm/‰ was obtained for X-polarization and maximum temperature sensitivity of −7.609nm/°C was obtained for Y polarization, which demonstrated that the designed scheme could not only solve the cross sensitivity problem of two parameters but also achieve high sensitivity. In addition, C-type micro-structured fiber is non-cascade integrated, strong stability, and flexibility in design, which has great potential for sensing applications.
Chiral Brønsted acid-catalysed asymmetric synthesis has received tremendous interest over the past decades, and numerous efficient synthetic methods have been developed based on this approach. ...However, the use of chiral Brønsted acids in these reactions is mostly limited to the activation of imine and carbonyl moieties, and the direct activation of carbon–carbon triple bonds has so far not been invoked. Here we show that chiral Brønsted acids enable the catalytic asymmetric dearomatization reactions of naphthol-, phenol- and pyrrole-ynamides by the direct activation of alkynes. This method leads to the practical and atom-economic construction of various valuable spirocyclic enones and 2H-pyrroles that bear a chiral quaternary carbon stereocentre in generally good-to-excellent yields with excellent chemo-, regio- and enantioselectivities. The activation mode of chiral Brønsted acid catalysis revealed in this study is expected to be of broad utility in catalytic asymmetric reactions that involve ynamides and the related heteroatom-substituted alkynes.Chiral Brønsted acid catalysis is mostly limited to the activation of imine and carbonyl moieties. Now, by direct activation of alkynes, chiral Brønsted acids have been used to enable the catalytic asymmetric dearomatization of naphthol-, phenol- and pyrrole-ynamides for the construction of various spirocyclic enones and 2H-pyrroles bearing a chiral quaternary carbon stereocentre.
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