Giant thermal conductivity in diamane and the influence of horizontal reflection symmetry on phonon scattering

Zhu, Liyan,Li, Wu,Ding, Feng Royal Society of Chemistry 2019 Nanoscale Vol.11 No.10

<P>Diamane, a chemically derived two-dimensional material, shows many superior physical and chemical properties similar to diamond thin films. Through the Peierls-Boltzmann transport equation, we reveal giant thermal conductivity in diamane with a stacking order of both AB and AA (respectively, abbreviated as D-AB and D-AA, hereafter) which are both comparable to that of diamond. Like in graphene, the phonon transport falls into the hydrodynamic regime even at room temperature, and the major contribution to the total thermal conductivity comes from the out-of-plane acoustic phonon modes (>40%). In addition, the thermal conductivity shows a dependence on the stacking order, namely, the thermal conductivity of D-AA, ∼2240 W m<SUP>−1</SUP> K<SUP>−1</SUP> at 300 K, is around 15% larger than that of D-AB, which is due to the strong restriction on the phonon scattering phase space induced by the horizontal reflection symmetry in D-AA. Such a kind of restriction, not limited to single atomic plane systems, is a general feature in two-dimensional materials with a horizontal reflection symmetry.</P>

Reducing the calculation of the linear complexities of -periodic sequences

Liyan zhu,ZhengQing Jiang 한국공학안전보건예술학회 2011 한국공학예술학회 논문지 Vol.3 No.-

We reduce the calculation of the linear complexity of the -periodic sequence under gcd(u,p) = 1 to the calculation of maximum of some linear complexities of -periodic sequences over Fp . And combining with the Berlekamp-Massy algorithm or generalized Games-Chan algorithm, we could efficiently compute the linear complexity of -periodic sequence. Thus we present an efficient and attractive algorithm for the calculation of the linear complexities of -periodic sequences.

Indicator of percolation transition in graphite oxide suspension containing cations

Liyan Liu,Jiale You,Haonan Zhu,Wei Tang 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.7

The percolation transition behavior occurs in the solid-liquid separation of graphite oxide (GO), whichchanges the system from suspension to colloid state and terminates the separation process. An indicator of percolationtransition is necessary to help control the status of GO suspension to finish the solid-liquid separation process. Theswell ratio, macroscopic appearance TEM, and rheological behavior of GO suspension were tested before and after thepercolation transition occurred in a specific interval of K+ concentration. Then, the physical properties of 1.00 g/L GOsuspension containing 0.40-0.80 g/L K+, including conductivity, thermal conductivity, viscosity, surface tension, andabsorbance were characterized. The values of these physical properties showed a sharp change in the specific interval ofK+ concentration. We calculated the first and second slope of two adjacent points of each physical property to obtain aproper percolation transition indicator. The conductivity with the second slope up to 500% was the most significantchange among these physical parameters, which can be used as an indicator of percolation transition in GO suspension. To verify the availability of the indicator, we explored the percolation transition behavior of Ca2+ and Al3+ in GOsuspension and K+ with different GO solid content, found that the conductivity is still the most significant percolationtransition indicator. The indicator obtained in this paper is reliable under varying content of GO and types of cations insuspension, which can be used to determine the percolation transition threshold during the solid-liquid separation ofGO suspension containing cations.

Optimization of operating conditions in the purification of graphite oxide dispersions

Guorui Zhu,Wei Tang,Ying Liu,Liyan Liu,Ranhao Xing 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.11

In the graphite oxide (GO) suspension purification process, some metallic impurities in GO cannot be separated. The residual metallic impurities dominate graphite oxide properties and have a negative influence on applications. Therefore, the removal of metallic impurities from graphite oxide has been brought into focus now. Single factor experiments and orthogonal experiments are used to get the optimal purification condition. The results show that purification agent, temperature, stirring intensity and contact time affect the purification degree, and the purification agent is the most important element for the purification efficiency. The optimal purification condition is 10% hydrochloric acid (H10), 20 oC, 0 rpm and 60 min. Besides, the theoretical stage is calculated by the mass conservation equation and distribution balance equation and the minimum stage is 3 under the optimal purification condition.

A Cross-National study of cloth’s purchasing behavior between Chinese and Korean Consumers

Mina Woo,Liyan Zhu,Chulmo Koo 한국호텔외식관광경영학회 2015 한국호텔외식경영학회 학술발표논문집 Vol.- No.-

Many researchers have been done from the aspect of comparing consumers from Western countries but few studies compared consumers within Asian market. With the development of tourism market between China and other Asian nations, more and more cross-national research should be done as the barriers between China and other countries fell down. The present research did an exploratory study on consumer behavior by comparing Chinese and Korean female consumers’ clothing purchase behavior in the decision-making process. Consumers’ purchasing decision making process can be classified into five stages: problem recognition, information search, alternative evaluation, purchase, and post acquisition behavior. This study compares these two groups at each of the former four stages by T-test The result shows that Chinese and Korean consumers are somewhat different in consumer needs in terms of the way to be satisfied with clothing, the way of gathering fashion information, the evaluation criteria of selecting clothing, and the selection of store. Compared with Koreans, Chinese females have more functional needs to be met through clothing, whereas Korean females have more experiential needs to be met. Although both Chinese and Koreans are considered as both collectivistic in previous researches, Koreans have a stronger tendency towards individualism than Chinese in purchasing clothing. Korean female consumers try to realize their needs to be unique and to express their internal attributes through clothing, while Chinese female consumers try to maintain social harmony and fit-in. The present study also conducted ANCOVA to see whether covariate income mediates the differences between Chinese and Korean respondents. ANCOVA result shows that most of these differences were caused by cultural difference with some also explained by different disposable income level between these two Asian countries. These implications give some hints to global marketers, especially marketers in tourism industry. The result of crossnational comparison of Asian consumers’ decision making process can provide valuable information to them in their development of international marketing strategies.

Distinct expression patterns and functions of the pygopus genes in amphioxus and zebrafish early embryogenesis

Guanghui Qian,Liyan Zhu,Guang Li,Xin Liu,Yiquan Wang 한국유전학회 2015 Genes & Genomics Vol.37 No.4

The Wnt/b-catenin transcriptional activation complex requires the adapter protein Pygopus (Pygo), which links the basal transcription machine to b-catenin to regulate the transcription of target genes. Previous studies revealed that the Pygo genes were broadly involved in the embryonic development of Drosophila, Xenopus and mouse, however, their functions in the embryonic development of amphioxus and zebrafish remain to be investigated. Here, we cloned and characterized one Pygo gene from amphioxus Branchiostoma belcheri (BbPygo) and two fromzebrafish Danio rerio (DrPygo1 and DrPygo2). The spatial–temporal expression profiles showed that all these genes were maternally expressed. BbPygo expression was distributed ubiquitously in the amphioxus embryos before the gastrula stage and became restricted in the pharyngeal region in late stages. Similar to BbPygo, DrPygo2 was also expressed throughout whole embryos before the early gastrula stage, but limited in the pharyngeal region and central nervous system (CNS) in subsequent developing stages. Further knockdown of the DrPygo2 resulted in developmental defects of the body axis, CNS and cartilage segments in zebrafish. In contrast, the expression signal of the DrPygo1 gene was not detectable using the in situ hybridization method, which is consistent with its extremely low expression level detected by RTqPCR. The expression patterns and function investigations revealed in this study suggest that the three Pygo genes probably function differentially though all of them show a conserved maternal expression pattern during the early embryonic stages of amphioxus and zebrafish.

Extraction of visual texture features of seabed sediments using an SVDD approach

Li, Yan,Liu, Shijie,Zhu, Puqiang,Yu, Jiancheng,Li, Shuo Pergamon Press 2017 Ocean engineering Vol.142 No.-

<P><B>Abstract</B></P> <P>Perception of the seabed environment is an important capability of autonomous underwater vehicles. This paper focuses on defining and extracting robust texture features from visual images that lead to useful and practical automated identification of the types of seabed sediments. The visual texture features are described by using a gray-level co-occurrence matrix (GLCM) and fractal dimension, after which an unsupervised learning method, self-organizing map (SOM), is adopted to evaluate the validity of features descriptors on three types of seabed sediments. Subsequently, a kernel-based approach that exhibits robustness versus low numbers of high-dimensional samples, named support vector domain description (SVDD), is applied to classify the types of seabed sediments. In comparison with state-of-the-art classifiers, the experimental results demonstrated the effectiveness of the SVDD on the classification of seabed sediments.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The visual images of seabed sediments are characterized by the texture features which are extracted based on the GLCM and fractal theory. </LI> <LI> A multi-class classification strategy for seabed sediments is proposed by adding a distance measure after SVDD implementation. </LI> <LI> The experimental results demonstrate that the proposed classification strategy is feasible in recognizing the type of seabed sediments. </LI> </UL> </P>