Browsing by Author "Zhang, Yuan"

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    Antonymous Adjectives in Disyllabic Lexical Compounds in Mandarin: A Cognitive Linguistics Perspective
    (Horizon Research Publishing,USA, 2015) Zhang, Yuan; Kemmer, Suzanne
    Corpus-based research into antonyms in English, Sweden and Japanese has gradually brought the lexical relation of antonymy into functional-cognitive linguistics in recent years. When antonymous adjectives are examined in Mandarin corpora, we find that they co-occur in both discontinuous constructions, for example, 既不热也不冷ji bure ye buleng, literally not hot also not cold, 'neither hot nor cold', and lexical compounds, often called disyllabic compounds, for example, 大小da xiao, literally big-small, 'size'. This study is a cognitive account of Mandarin disyllabic compound constructions composed of two antonymous adjective roots, such as长短chang duan, literally long-short, 'length', 左右zuo you, literally left-right, 'control', and 反正 fan zheng, literally back-face, 'anyway'. With the help of the Lancaster corpus of Mandarin Chinese (LCMC) and the corpus from the Center for Chinese Linguistics (CCL), 51 instances of antonymous adjective compounds were retrieved. When the antonymous adjectives co-occur, there are interactions between the componential semantics and the constructional semantics. While the disyllabic compound constructions may inherit the part of speech from their components, they may also have their own part of speech, functioning as nouns, adverbs and even verbs. The different categories reflect different construals of the same conceptual content. In a nutshell, by adopting a cognitive linguistics approach, we show that the different uses of these compounds are related in a systematic way.
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    Atomically thin gallium layers from solid-melt exfoliation
    (AAAS, 2018) Kochat, Vidya; Samanta, Atanu; Zhang, Yuan; Bhowmick, Sanjit; Manimunda, Praveena; Asif, Syed Asif S.; Stender, Anthony S.; Vajtai, Robert; Singh, Abhishek K.; Tiwary, Chandra S.; Ajayan, Pulickel M.
    Among the large number of promising two-dimensional (2D) atomic layer crystals, true metallic layers are rare. Using combined theoretical and experimental approaches, we report on the stability and successful exfoliation of atomically thin “gallenene” sheets on a silicon substrate, which has two distinct atomic arrangements along crystallographic twin directions of the parent α-gallium. With a weak interface between solid and molten phases of gallium, a solid-melt interface exfoliation technique is developed to extract these layers. Phonon dispersion calculations show that gallenene can be stabilized with bulk gallium lattice parameters. The electronic band structure of gallenene shows a combination of partially filled Dirac cone and the nonlinear dispersive band near the Fermi level, suggesting that gallenene should behave as a metallic layer. Furthermore, it is observed that the strong interaction of gallenene with other 2D semiconductors induces semiconducting to metallic phase transitions in the latter, paving the way for using gallenene as promising metallic contacts in 2D devices.
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    Exfoliation, Characterizations, and Applications of 2D Gallium Sheets
    (2016-11-30) Zhang, Yuan; Ajayan, Pulickel
    The isolation of graphene from graphite have boomed the two dimensional materials research for many years. The metallic layers have been studied rarely, so I decided to explore the two-dimensional gallium layer. Unlike the traditional top-down techniques of exfoliation, I here develop a novel solid-melt interface exfoliation technique, which take advantages of the interface between the solid and molten phases of the gallium. Some characterization figures will be reported to study the thickness, the morphology, the crystal nature, and the composition details. I also used the standard electron beam lithography to fabricate the gallium device, which helps to investigate the electronic properties of the atomic-thick gallium layer. At last, to prove the scalability and reproducibility of the solid-melt exfoliation technique, I used a new stamping technique to create gallium layers showing a successful rate between 80%-90%, which could be established to a unique and innovative metal stamping technique in future industry. Also, I provided several possible improvements and insights about my own project, which may worth a try in future study. At last, the progress and challenges of the two dimensional materials area will be covered according to my own understanding.