Search

Graphite films are widely used in microelectronic devices as heat-dissipation materials due to their high thermal conductivity, low thermal expansion coefficient and lightweight. In the 5G era, the miniaturization and integration of microelectronic devices are continuously improving, so there are higher requirements for heat-dissipation materials. Therefore, flexible graphite films with high thermal conductivity are urgently needed. In this work, nickel-coated CNTs (Ni@CNTs) were prepared first as additives to be incorporated into the PI matrix via in situ polymerization, and then the Ni@CNTs/PI composite films were carbonized and graphitized at high temperature to form graphite films. In this composite system, nickel particles can effectively improve the graphitization degree of the obtained graphite films, which is beneficial to the improvement of their thermal conductivity, as well as the CNTs can effectively enhance the cross-plane thermal conductivity and mechanical strength of the graphite films. The graphite films obtained from the graphitization of PI/Ni@CNTs (0.4 wt%) have a perfect graphene structure and optimal properties. The optimal layer thickness of graphene is 0.3354 nm, while the d-spacing of the graphite layers is around 0.3358 nm. The in-plane thermal conductivity is 1.13 times greater than that of the graphite film made from the pure PI film (G0 film), which has a value of 1198.5 W m−1 K−1. The cross-plane thermal conductivity is 6.26 W m−1 K−1, which is 2.96 times that of the G0 film (2.11 W m−1 K−1). The bending strength is 72.3 Mpa, which is 2.28 times that of the G0 film (31.7 Mpa). The introduction of Ni@CNTs greatly improves the comprehensive properties of graphite films, and the preparation technology has an important guiding significance for the preparation of high thermal conductivity flexible graphite films and important industrial application value. [ABSTRACT FROM AUTHOR]

A large Stokes-shifted fluorescent imide (HBTN-MC) and its related polyimides (HBHBTNms and HPHBTNms) were first designed and synthesized by introducing an excited state intramolecular proton transfer fluorophore 2-(2′-hydroxyphenyl)benzothiazole (HBT). The imide exhibited a large Stokes shift of 9654 cm−1 in the dichloromethane solution and 7648 cm−1 in the solid state. Based on the experimental and theoretical methods, the photophysical properties and the excited state intramolecular proton transfer (ESIPT) process of HBTN-MC have been systematically studied. The performances of the polyimides have been optimized by changing the alicyclic dianhydride and adjusting the copolymerization ratio. The as-prepared polyimide films retained the ESIPT performance with a large Stokes shift of larger than 8105 cm−1, a high photoluminescence quantum efficiency (ϕ) of 29%, decent colorless and transparency, high thermal performance (Td, 5% = 468 °C and Tg > 260 °C), and solubility in both conventional aprotic and protic solvents. In short, the newly developed imide and polyimides provide good examples for the development of ESIPT polymers with controllable emission wavelengths as well as high thermal, environmental, and radiation stability. [ABSTRACT FROM AUTHOR]

Abstract With the increased use of time series data in human research, ranging from ecological momentary assessments to data passively obtained, researchers can explore dynamic processes more than ever before. An important question researchers must ask themselves is, do I think all individuals have similar processes? If not, how different, and in what ways? Dr. Peter Molenaar’s work set the foundation to answer these questions by providing insight into individual-level analysis for processes that are assumed to differ across individuals in at least some aspects. Currently, such assumptions do not have a clear taxonomy regarding the degree of homogeneity in the patterns of relations among variables and the corresponding parameter values. This paper provides the language with which researchers can discuss assumptions inherent in their analyses. We define strict homogeneity as the assumption that all individuals have an identical pattern of relations as well as parameter values; pattern homogeneity assumes the same pattern of relations but parameter values can differ; weak homogeneity assumes there are some (but not all) generalizable aspects of the process; and no homogeneity explicitly assumes no population-level similarities in dynamic processes across individuals. We demonstrate these assumptions with an empirical data set of daily emotions in couples. [ABSTRACT FROM AUTHOR]

Despite considerable interest in the causes and consequences of work-family conflict, and the frequent suggestion in fertility research that difficulty in balancing work and family is one of the factors leading to low fertility rates in several developed countries, little research uses longitudinal data to examine whether women who report difficulty in balancing their work and family roles go on to have fewer subsequent births. This article uses longitudinal data from the National Institute of Child Health and Human Development Study of Early Child Care (N = 809) to examine whether difficulties in balancing work and family are associated with fewer subsequent births. Our results provide little support for the idea that working women in the United States who have difficulty in balancing work and family delay or forgo having additional children. Instead, women in the United States may achieve their fertility goals at the expense of continued labor force participation.

This study investigated the performance of fit indexes in selecting a covariance structure for longitudinal data. Data were simulated to follow a compound symmetry, first-order autoregressive, first-order moving average, or random-coefficients covariance structure. We examined the ability of the likelihood ratio test (LRT), root mean square error of approximation (RMSEA), comparative fit index (CFI), and Tucker-Lewis Index (TLI) to reject misspecified models with varying degrees of misspecification. With a sample size of 20, RMSEA, CFI, and TLI are high in both Type I and Type II error rates, whereas LRT has a high Type II error rate. With a sample size of 100, these indexes generally have satisfactory performance, but CFI and TLI are affected by a confounding effect of their baseline model. Akaike's Information Criterion (AIC) and Bayesian Information Criterion (BIC) have high success rates in identifying the true model when sample size is 100. A comparison with the mixed model approach indicates that separately modeling the means and covariance structures in structural equation modeling dramatically improves the success rate of AIC and BIC. (Contains 4 tables and 5 figures.)

Information‐Centric Networking (ICN) changes the network communication mode from host‐centric to information‐centric, which directly identifies content in a unified manner and conducts positioning, routing and transmission based on content. In‐network caching is used to speed up content distribution and build the network into an integrated platform for information transmission, storage and service. ICN is regarded as one of the most promising next generation internet architectures. Because of in‐network caching strategy of ICN, English corpus content is cached by ICN router, so as to perform real‐time English translation. Therefore, this study proposes a caching strategy based on English corpus content popularity. Compared with the existing caching strategy, the experimental results demonstrate that the proposed strategy can improve lagging probability, latency and accuracy in real‐time English translation. The real‐time English translation is performed through the English corpus content, and the router caches the corpus content. After user request routing in the process of translation, if the related translation content hit the cache en‐route, it will respond directly instead of obtaining the corpus from the server every time. Through nearby services, the transmission efficiency of corpus content is improved, and fast response and real‐time translation are achieved. [ABSTRACT FROM AUTHOR]