The Effects of Hypertext Glosses on L2 Vocabulary Acquisition: A Meta-Analysis

In the field of second language acquisition (SLA), "comprehensible input" (Krashen, 1985) has been considered a critical factor to help learners acquire foreign and second languages (L2). From this perspective, the notion of extensive or free voluntary reading (Day & Bamford, 1998; Krashen, 1993) has emerged that L2 learners should be given more pleasure reading by minimizing a burden look-up behavior. At the same time, technology innovation has made it possible for extensive reading to occur through technology over the past decades. In particular with hypertext glosses or multimedia annotations, a number of studies have indicated that hypertext glossed input is comprehensible input and has made it possible for L2 readers to benefit all from extensive reading. This study examines (1) effects of hypertext gloss use on L2 vocabulary acquisition in computerized reading contexts, and (2) which specific combination of either text-only (single) or text + visual (multiple) hypertext glosses is more effective on L2 vocabulary acquisition and 3) What potential moderators to systematically account for between study variation are. In addition, it aims to synthesize characteristics of studies, technology use and research methods from empirical research studies for a comprehensible and insightful review of the effect of hypertext glosses on L2 vocabulary acquisition. Meta-analysis as a quantitative method was conducted to synthesize overall findings of empirical studies by calculating a standardized mean difference effect size. From 300 papers considered, 10 met the Criteria for Inclusion through a final filtering process, and were finally meta-analyzed to extract effect sizes in the present study. On the basis of 35 weighted mean effect size, 0.46 (Cohen, 1988: medium), the magnitude of text + visual (multiple) hypertext gloss combination was moderately effective on L2 vocabulary acquisition when L2 learners were given two conditions: a text-only or a text + visual hypertext glosses. The results revealed that various L2 learners, including English as a second or foreign language (ESL/EFL), Spanish as a foreign language (SFL), Japanese as a foreign language (JFL), and German as a foreign language (GFL), benefit from multiple hypertext glosses while reading computerized texts. In terms of research design, hypertext gloss studies have been almost always conducted in settings of class session-based quasi-experiment design with a researcher-developed program at a university or college level. More implications are discussed for future research

Unveiling the carrier transport mechanism in epitaxial graphene for forming wafer-scale, single-domain graphene

Graphene epitaxy on the Si face of a SiC wafer offers monolayer graphene with unique crystal orientation at the wafer-scale. However, due to carrier scattering near vicinal steps and excess bilayer stripes, the size of electrically uniform domains is limited to the width of the terraces extending up to a few microns. Nevertheless, the origin of carrier scattering at the SiC vicinal steps has not been clarified so far. A layer-resolved graphene transfer (LRGT) technique enables exfoliation of the epitaxial graphene formed on SiC wafers and transfer to flat Si wafers, which prepares crystallographically single-crystalline monolayer graphene. Because the LRGT flattens the deformed graphene at the terrace edges and permits an access to the graphene formed at the side wall of vicinal steps, components that affect the mobility of graphene formed near the vicinal steps of SiC could be individually investigated. Here, we reveal that the graphene formed at the side walls of step edges is pristine, and scattering near the steps is mainly attributed by the deformation of graphene at step edges of vicinalized SiC while partially from stripes of bilayer graphene. This study suggests that the two-step LRGT can prepare electrically single-domain graphene at the wafer-scale by removing the major possible sources of electrical degradation

Fabrication of Complex Three-Dimensional Structures of Mica through Digital Light Processing-Based Additive Manufacturing

Mica is a group of clay minerals that are frequently used to fabricate electrical and thermal insulators and as adsorbents for the treatment of cationic pollutants. However, conventional subtractive manufacturing has the drawback of poor three-dimensional (3D) shape control, which limits its application. In this study, we propose digital light processing (DLP)-based additive manufacturing (AM) as one of the most effective ways to address this drawback. Two major challenges for the ceramic DLP process are the production of a homogeneous and stable slurry with the required rheological properties and the maintenance of printing precision. The mica green body was fabricated using a 53 vol.% solid loading slurry through DLP, which exhibited good dimensional resolution under an exposure energy dose of 10 mJ/cm2. The precise, complex 3D structure was maintained without any defects after debinding and sintering at 1000 °C. The use of ceramic AM to overcome the shape-control limitations of mica demonstrated in this study offers great potential for expanding the applications of mica

Unveiling the carrier transport mechanism in epitaxial graphene for forming wafer-scale, single-domain graphene.

Graphene epitaxy on the Si face of a SiC wafer offers monolayer graphene with unique crystal orientation at the wafer-scale. However, due to carrier scattering near vicinal steps and excess bilayer stripes, the size of electrically uniform domains is limited to the width of the terraces extending up to a few microns. Nevertheless, the origin of carrier scattering at the SiC vicinal steps has not been clarified so far. A layer-resolved graphene transfer (LRGT) technique enables exfoliation of the epitaxial graphene formed on SiC wafers and transfer to flat Si wafers, which prepares crystallographically single-crystalline monolayer graphene. Because the LRGT flattens the deformed graphene at the terrace edges and permits an access to the graphene formed at the side wall of vicinal steps, components that affect the mobility of graphene formed near the vicinal steps of SiC could be individually investigated. Here, we reveal that the graphene formed at the side walls of step edges is pristine, and scattering near the steps is mainly attributed by the deformation of graphene at step edges of vicinalized SiC while partially from stripes of bilayer graphene. This study suggests that the two-step LRGT can prepare electrically single-domain graphene at the wafer-scale by removing the major possible sources of electrical degradation

Stone-Wales defect-rich carbon-supported dual-metal single atom sites for Zn-air batteries

This work aims to obtain a fundamental understanding of active sites near stone-wales (SW) defects rich nitrogen-doped graphene (DG) with specific coordination of carbon atom rings. It reveals that the SW rich defects (e.g., pentagon (5), pentagon—octagon—pentagon (i.e. 585), or pentagon-heptagon-heptagon-pentagon (5775) rings, appears correspondingly with carbon rings that brought active sites during catalytic reactions. Moreover, we anchored dual isolated metallic atoms (Ni/Fe) on DG support via linkers (O/N) called NiFe-DG. X-ray absorption spectroscopy indicates Ni/Fe metal single atoms are embedded via Fe-N4 and Ni-N4 coordination on DG surfaces. It exhibits high catalytic activity for oxygen reduction reaction (ORR) with an onset potential of 0.97 V, a half-wave potential of 0.86 V, and diffusion current density of 5.7 mA cm− 2, which is at par with commercial Pt/C. The catalyst shows superior stability, retained 82% of the initial current density even after 12 h under an applied potential of 0.86 V. Similarly, the oxygen evolution reaction (OER) overpotential of 358 mV was achieved at 10 mA cm− 2 with a lower Tafel slope value (76 mV/dec) than commercial Pt/C. It maintains 85% stability for 12 h at a constant potential of 1.588 V, shows better stability than commercial Pt/C.</p

Vertical Metal-Oxide Electrochemical Memory for High-Density Synaptic Array Based High-Performance Neuromorphic Computing

Cross-point arrays of analog synaptic devices are expected to realize neuromorphic computing hardware for neural network computations with compelling speed boost and superior energy efficiency, as opposed to the conventional hardware based on the von Neumann architecture. To achieve desired characteristics of analog synaptic devices for fully parallel vector-matrix multiplication and vector-vector outer-product updates, metal-oxide based electrochemical random-access memory (ECRAM) is proposed as a promising synaptic device due to its complementary metal-oxide-semiconductor-compatibility and outstanding synaptic characteristics over other non-volatile memory candidates. In this work, ECRAM devices with 3D vertical structure is fabricated to demonstrate a minimal 4F(2) cell size, highly scalable channel volume and low programming energy, providing optimized synaptic device performance and characteristics as well as high integrity as a cross-point array. Various weight-update profiles of the vertical ECRAM devices are obtained by adjusting programming voltage pulses, exhibiting trade-offs among dynamic range, linearity, symmetry, and update deviation. Based on simulation with advanced algorithms for analog cross-point array and neural network designs, the potential of vertical ECRAM for high-density array is evaluated. Simulation studies suggest that the neuromorphic computing performance can be improved further by balancing the weight update characteristics of vertical ECRAM.N