Infrared anomalies in ultrathin Ti3C2Tx MXene films

Visible transparent but infrared reflective materials are ideal candidates for both transparent conductive films and low-emissivity glass, which are highly desired in a broad variety of areas such as touchscreens and displays, photovoltaics, smart windows, and antistatic coatings. Ultrathin Ti3C2Tx MXene films are emerging as promising low-emissivity transparent candidates. However, the fundamental IR properties of Ti3C2Tx has not been revealed experimentally due to daunting challenges in the preparation of continuous, large-area, and ultrathin films of optical quality on flat substrates. Herein, we proposed a tape-free transfer method that can help prepare centimeter-size and ultrathin (down to 8 nm) Ti3C2Tx films on diverse optical substrates. Benefitting from this method, the refractive index and permittivity for Ti3C2Tx were successfully measured. Ti3C2Tx films exhibit large in-plane permittivity in the IR region, yielding maximum IR reflectance of 88% for bulk films. Interestingly, three anomalies were found in ultrathin Ti3C2Tx films: strong dispersion in the permittivity, interlayer space-dependent optical properties, and abnormally high IR absorption for a 15-nm-thick film. These anomalies are important guidelines in the design of Ti3C2Tx-based low-emissivity transparent films and other related devices, and may inspire other intriguing applications such as ultrathin IR absorption coatings and tunable IR optical devices

Middle school students' mental unwellness and academic performance in China: The effects of parental involvement.

This study investigated the relationship between the mental unwellness of middle school students in China and their academic performance in the subjects of Chinese, mathematics, and English. Additionally, this study explored the potential ameliorating effects of parental involvement variables (parental non-academic activity involvement and parent-child communication) on the adverse impact of mental unwellness on academic performance. The examination of the effects of parental involvement also considered the differential effects of involvement by mothers and fathers. This study utilized national longitudinal representative data from the China Education Panel Survey (CEPS). Findings of the two-level Hierarchical Linear Modeling (HLM) analyses indicated that mental unwellness in Grade 7 negatively impacted academic performance in the aforementioned subjects in Grade 8. Nonetheless, these adverse impacts were alleviated when the parental involvement variables were taken into account. Furthermore, the results revealed that mother-child communication and father-child communication had moderating effects on the negative relationship between mental unwellness and academic performance in Chinese and English, respectively. This study contributes to the existing literature by shedding light on the beneficial effects of parental involvement and highlighting the differential involvement of mothers and fathers

Asian American Students' Postsecondary STEM Education Pathways

This study aims to understand Asian American students’ postsecondary STEM education pathways. It examined Asian American students as a whole and as geographical and generational subgroups. It studied postsecondary STEM education as a whole and as five different fields. It examined STEM pathways through six research topics. And, it explored factors that related to Asian American students’ STEM education pathways. This study contributes to the current research body by focusing on an important matter that needs more exploration, by offering justifiable definitions and classifications of Asian Americans and STEM education, and by suggesting related factors of STEM education. An US national representative and longitudinal data set, Education Longitudinal Study of 2002 (ELS: 2002), was utilized in this study to explore the intended research topics. SPSS, R, and AM were used for the analyses. Missing data imputation was applied. When analyzing the data, the nested structure of ELS: 2002 was considered. And, both descriptive and inferential analyses were carried out. The descriptive analyses were used both as a preparation for inferential analyses and as ways to answer the research questions. The inferential analyses were realized through stepwise logistic regressions. With three regressions for Asian Americans as a whole and three regressions for Asian Americans as subgroups, six stepwise regressions were conducted for the research topics of postsecondary enrollment, STEM choice as a whole, and STEM completion as whole. Due to the limitation of the analytic sample sizes, the research topics of STEM as an individual major choice, STEM individual major completion, and STEM individual major persistence were not examined by using regressions. This study found that Asian American students were generally more likely to receive postsecondary education and major in STEM fields than White students. Among the five STEM fields, Asian American and White students both favored the fields of biological/agricultural sciences and engineering/engineering technologies. Both Asian American and White students were likely to obtain STEM degrees and persist in the same STEM fields they originally chose. More importantly, examination of the within-Asian American differences indicated that basically no difference was found among Asian American subgroups at certain stages of STEM education: receiving postsecondary education, choosing a STEM major, obtaining a STEM degree, and persisting in the same STEM fields. Nevertheless, Asian American subgroup disparities were found in choosing and obtaining a degree in different STEM fields. On the other hand, different stages of Asian American students’ postsecondary STEM education pathways did not involve the same related factors. Moreover, the same factors did not exhibit the same relative status at different pathway stages. The results imply the importance for future research to examine the within- Asian American and STEM education differences. Also, they have implications for ways to increase postsecondary enrollment, STEM major choice, and STEM degree obtainment