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Open Access Publications from the University of California

Scholarly Works (3 results)

  • Article
  • Peer Reviewed
The Proceedings of the International Plant Nutrition Colloquium XVI (2009)

The main objectives of this study were to elucidate the roles of silicon (Si) in alleviating cadmium-induced oxidative stress in roots of pakchoi grown hydroponically using two contrasting pakchoi (Brassica chinensis L.) cultivars: cv. Shanghaiqing (SHQ), a Cd-sensitive cultivar and cv. Hangyoudong (HYD), a Cd-tolerant cultivars. Lipid peroxidation, enzymatic and non-enzymatic antioxidants and histochemical stainning were examined in the two pakchoi plants grown under lower (0.5 mg Cd L-1) and higher (5 mg Cd L-1) Cd stress without or with 1.5 mM Si. Root length was decreased by Cd stress, especially in the sensitive cultivar. Addition of Si significantly increased root length of both cultivars under both levels of Cd tested. The decreases in activities of superoxide dismutase (SOD), catalase (CAT), asorbate peroxidases (APX) and increases in concentrations of malondialdehyde (MDA) were observed in the Cd treatments, which were all counteracted by addition of Si. These alleviative effects of Si were more significant in the Cd-tolerant cultivar than in the Cd-sensitive cultivar. Such effects were confirmed by using histochemical staining methods. All these results suggest that Si-mediated alleviation of Cd toxicity be attributed mainly to Si-enhanced root length, antioxidant defense capacity and membrane integrity and to Si-suppressed oxidative damage.

    Cover page: Silicon-mediated alleviation of cadmium toxicity in roots of Brassica chinensis is mainly attributable to silicon-enhanced antioxidant defense capacity and silicon-suppressed oxidative damage
    • Article
    • Peer Reviewed
    UC Irvine Previously Published Works (2020)
    Human adults are faster to respond to small/large numerals with their left/right hand when they judge the parity of numerals, which is known as the SNARC (spatial-numerical association of response codes) effect. It has been proposed that the size of the SNARC effect depends on response latencies. The current study introduced a perceptual orientation task, where participants were asked to judge the orientation of a digit or a frame surrounding the digit. The present study first confirmed the SNARC effect with native Chinese speakers (Experiment 1) using a parity task, and then examined whether the emergence and size of the SNARC effect depended on the response latencies (Experiments 2, 3, and 4) using a perceptual orientation judgment task. Our results suggested that (a) the automatic processing of response-related numerical-spatial information occurred with Chinese-speaking participants in the parity task; (b) the SNARC effect was also found when the task did not require semantic access; and (c) the size of the effect depended on the processing speed of the task-relevant dimension. Finally, we proposed an underlying mechanism to explain the SNARC effect in the perceptual orientation judgment task.
      Cover page: Automaticity in processing spatial-numerical associations: Evidence from a perceptual orientation judgment task of Arabic digits in frames
      • Article
      • Peer Reviewed
      UC Berkeley Previously Published Works (2021)
      Structural defects vary the optoelectronic properties of monolayer transition metal dichalcogenides, leading to concerted efforts to control defect type and density via materials growth or postgrowth passivation. Here, we explore a simple chemical treatment that allows on-off switching of low-lying, defect-localized exciton states, leading to tunable emission properties. Using steady-state and ultrafast optical spectroscopy, supported by ab initio calculations, we show that passivation of sulfur vacancy defects, which act as exciton traps in monolayer MoS2 and WS2, allows for controllable and improved mobilities and an increase in photoluminescence up to 275-fold, more than twice the value achieved by other chemical treatments. Our findings suggest a route for simple and rational defect engineering strategies for tunable and switchable electronic and excitonic properties through passivation.
        Cover page: Rational Passivation of Sulfur Vacancy Defects in Two-Dimensional Transition Metal Dichalcogenides
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