Fluid dynamics: an emerging route for the scalable production of graphene in the last five years

Bulk applications of graphene in fields such as advanced composites, conductive ink, and energy storage require cheap and scalable graphene. Fortunately, in the last decade, liquid-phase exfoliation of graphite to give pristine graphene has been thought as a promising way to massive production of graphene at high efficiency and low cost, in terms of the cheap and abundant graphite source and a variety of cost-effective exfoliation techniques. Though many exfoliation techniques are available so far, this article will highlight the recent progress of fluid dynamics route which emerges as a promising scalable and efficient way for graphene production in the last five years. The emphasis is set on vortex fluidic devices and pressure- and mixer-driven fluid dynamics, with our perspectives on the latest progress, exfoliation mechanism, and some key issues that require further study in order to realize industrial applications.Comment: 18 figure

Contract Enforcement and Family Control of Business: Evidence from China

Family control of business is prevalent in developing economies, and one of the leading theories suggests that it is a response to weak contract enforcement in such economies. In this paper, we investigate the impacts of contract enforcement on the degree of family control of business using a sample of China's private enterprises. It is found that weaker contract enforcement is associated with the higher degree of family control of business. Our results are robust to the control for omitted variables and reserve causality issues, to the adjustment for the sample attrition bias, to the use of a sub-sample, and to the inclusion of other explanations for the family control of business.Family Control of Business, Contract Enforcement, China's Private Enterprises

Pure Exporter: Theory and Evidence

This paper provides the first evidence about pure exporters (i.e., firms exporting all of their output to the foreign market) -- a phenomenon overlooked and cannot be explained in the existing literature. It then offers a generalized model of Melitz (2003) for examining the existence and behavior of pure exporters. In particular, pure exporters arise when the export market is sufficiently large -- a situation more likely to hold in developing countries as opposed to large developed countries; and their productivity levels are above those of non-exporters, but below those of firms having both domestic sales and export. These theoretical predictions are borne out in a data of Chinese manufacturing firms for the period of 1998-2005.Pure Exporter, Firm Heterogeneity, Exporting Behavior

A Convex Formulation for Spectral Shrunk Clustering

Spectral clustering is a fundamental technique in the field of data mining and information processing. Most existing spectral clustering algorithms integrate dimensionality reduction into the clustering process assisted by manifold learning in the original space. However, the manifold in reduced-dimensional subspace is likely to exhibit altered properties in contrast with the original space. Thus, applying manifold information obtained from the original space to the clustering process in a low-dimensional subspace is prone to inferior performance. Aiming to address this issue, we propose a novel convex algorithm that mines the manifold structure in the low-dimensional subspace. In addition, our unified learning process makes the manifold learning particularly tailored for the clustering. Compared with other related methods, the proposed algorithm results in more structured clustering result. To validate the efficacy of the proposed algorithm, we perform extensive experiments on several benchmark datasets in comparison with some state-of-the-art clustering approaches. The experimental results demonstrate that the proposed algorithm has quite promising clustering performance.Comment: AAAI201

Quantum oscillations and three-dimensional quantum Hall effect in ZrTe5_5

Recent experiments have reported a lot of spectacular transport properties in topological materials, such as quantum oscillations and three-dimensional (3D) quantum Hall effect (QHE) in ZrTe$_5$. In this paper, by using a strong topological insulator model to describe ZrTe$_5$, we study the magnetotransport property of the 3D system. With fixed carrier density, we find that there exists a deferring effect in the chemical potential, which favors distinguishing the saddle points of the inverted LLs. On the other hand, with fixed chemical potential, the features of 3D QHE are demonstrated and we attribute the underlying mechanisms to the interplay between Dirac fermions, magnetic field and impurity scatterings.Comment: 11 pages, 5 figure

The Effectiveness of a Hybrid Cybersecurity Summer Camp for Teachers

Cybersecurity teacher education plays a vital role in narrowing the gap in the need for cybersecurity professionals in the workforce. In this paper, the authors examined the effectiveness of a hybrid cybersecurity summer camp for secondary education in-service teachers. The pre- and post-camp quizzes showed significant statistical difference, t(17) = -8.42, p \u3c .001, with a large effect size of 2.24. Focus group interviews with the teacher participants further suggested that the hybrid modality is not only viable but also a preferred format welcomed by the teachers

Learning-by-Teaching in CS Education: A Systematic Review

To investigate the strategies and approaches in teaching Computer Science (CS), we searched the literature review in CS education in the past ten years. The reviews show that learning-by-teaching with the use of technologies is helpful for improving student learning. To further investigate the strategies that are applied to learning-by-teaching, three categories are identified: peer tutoring, game-based flipped classroom, and teachable agents. In each category, we further searched and investigated prior studies. The results reveal the effectiveness and challenges of each strategy and provide insights for future studies