Formation of mononuclear N,O-chelate zirconium complexes by direct insertion of epoxide into tetrakis(dimethylamido)zirconium: highly promising approach for developing an ALD precursor of ZrO2 thin films.

A zirconium complex containing an N,O-chelate and alkylamide ligand has great potential for application in atomic layer deposition (ALD). However, the synthesis of this mononuclear Zr complex remains a major challenge because of the highly electrophilic nature and rich coordination of the Zr(IV) atom. Herein, a nonclassical and highly effective route for synthesizing the mononuclear N,O-chelate Zr complex was envisaged and verified using rationally designed reactions, involving the ring-opening insertion of epoxide into tetrakis(dimethylamido)zirconium(IV) (TDMAZ) at room temperature. To the best of our knowledge, very few studies in which mononuclear Zr complexes comprising alkylamide in combination with aminoalkoxide are structurally characterized. This method is extremely simple, atom economical, and easily scalable. Importantly, the produced precursor complex enables ALD of ZrO2 at a satisfactory growth rate (0.93 Å per cycle), close to that of the commercial ALD precursor CpZr(NMe2)3 (0.9 Å per cycle).

Changes in air pollution levels after COVID-19 outbreak in Korea.

In order to control the spread of COVID-19, social distancing measures were implemented in many countries. This study investigated changes in air pollution during the social distancing after the COVID-19 outbreak in Korea. Ambient PM2.5, PM10, NO2, and CO that are particularly related to industrial activities and traffic were reduced during the social distancing in response to the COVID-19 outbreak. In March 2020, immediately after social distancing, mean levels of PM2.5, PM10, NO2, and CO decreased nationwide from last year's mean levels by 16.98 µg/m3, 21.61 µg/m3, 4.16 ppb, and 0.09 ppm, respectively (p-value for the year-to-year difference <0.001, =0.001, =0.008, <0.001), a decrease by 45.45%, 35.56%, 20.41%, and 17.33%, respectively. Changes in ambient O3 or SO2 were not observed to be attributable to social distancing. Our findings, that such effort for a short period of time resulted in a significant reduction in air pollution, may point toward reducing air pollution as a public health problem in a more sustainable post-COVID-19 world.

Full-Color-Tunable Nanophotonic Device Using Electrochromic Tungsten Trioxide Thin Film.

Color generation based on strategically designed plasmonic nanostructures is a promising approach for display applications with unprecedented high-resolution. However, it is disadvantageous in that the optical response is fixed once the structure is determined. Therefore, obtaining high modulation depth with reversible optical properties while maintaining its fixed nanostructure is a great challenge in nanophotonics. In this work, dynamic color tuning and switching using tungsten trioxide (WO3), a representative electrochromic material, are demonstrated with reflection-type and transmission-type optical devices. Thin WO3 films incorporated in simple stacked configurations undergo dynamic color change by the adjustment of their dielectric constant through the electrochromic principle. A large resonance wavelength shift up to 107 nm under an electrochemical bias of 3.2 V could be achieved by the reflection-type device. For the transmission-type device, on/off switchable color pixels with improved purity are demonstrated of which transmittance is modulated by up to 4.04:1.

Do Individual Differences and Aging Effects in the Estimation of Geographical Slant Reflect Cognitive or Perceptual Effects?

Several individual differences including age have been suggested to affect the perception of slant. A cross-sectional study of outdoor hill estimation (N = 106) was analyzed using individual difference measures of age, experiential knowledge, fitness, personality traits, and sex. Of particular note, it was found that for participants who reported any experiential knowledge about slant, estimates decreased (i.e., became more accurate) as conscientiousness increased, suggesting that more conscientious individuals were more deliberate about taking their experiential knowledge (rather than perception) into account. Effects of fitness were limited to those without experiential knowledge, suggesting that they, too, may be cognitive rather than perceptual. The observed effects of age, which tended to produce lower, more accurate estimates of hill slant, provide more evidence that older adults do not see hills as steeper. The main effect of age was to lower slant estimates; such effects may be due to implicit experiential knowledge acquired over a lifetime. The results indicate the impact of cognitive, rather than perceptual factors on individual differences in slant estimation.