Applied Nanophotonics with Two-Dimensional Materials

University of Technology Sydney. Faculty of Science.Silicon semiconductor technology has revolutionized electronics beyond the imagination of pioneering scientists. This technology's rate of progress since 1947 has been enormous, with the number of transistors on a single chip growing from a few thousand in the earliest transistors to more than two billion today. However, there seems to be a limit to the miniaturization of electronics chips, when the size of individual transistors can no longer be reduced, or they become unstable when quantum tunneling starts to kick in at a few atoms limit. Therefore, there is an urgent need to complement Si CMOS technology and to fulfil future computing requirements as well as the need for diversification of applications with new materials. In that context, two-dimensional (2D) materials emerge as a promising alternative. They demonstrate a range of superior optical and electronic properties, which are essential for future optoelectronic applications. In the crystal form, thin layers of these materials are stacked and held together by relatively weak van der Waals forces. Consequently, it is easier to exfoliate and transfer them to a target substrate by a simple tape exfoliation and stamping method. This is a substantial advantage of 2D materials over their three-dimensional (3D) counterparts for incorporation in devices. 2D materials promise a heterogeneous platform that is particularly appealing for on-chip integration, owing to their small footprints and compatibility with semiconductor technology. In this thesis, we investigate the engineering of hexagonal boron nitride (hBN) at the nanoscale to generate single photon emitters in hBN flakes and nanoparticles. Next, we discuss the effort to develop novel nanophotonic platforms by integrating hBN quantum emitters in dielectric waveguides; we successfully coupled and propagated quantum light in hBN through the waveguides. Finally, we present the work on the incorporation of transition metal dichalcogenide (TMDC) material in a circular Bragg's grating structure to improve the directionality of the emitted photon stream and light extraction efficiency

The Relationship between Foreign Direct Investment, Electricity Consumption and Economic Growth in Vietnam

One of the prerequisites for the successful implementation of national industrialization and modernization is the synchronous development of fundamental industries. Electricity is a key industry that determines the success of other industries. The main purpose of this paper is to investigate the causal relationship between electricity consumption, foreign direct investment and economic growth in Vietnam during the period 1990-2015, by using Toda-Yamamoto approach and autoregressive distributed lag (ARDL) approach. The empirical results show strong statistical evidence that electricity consumption and foreign direct investment have positive impacts on economic growth in Vietnam in both short term and long term. Keywords: FDI, electricity consumption, economic growth, Vietnam. JEL Classifications: F21; F43; Q4

Effects of High-Energy Electron Irradiation on Quantum Emitters in Hexagonal Boron Nitride

© 2018 American Chemical Society. Hexagonal boron nitride (hBN) mono and multilayers are promising hosts for room-temperature single photon emitters (SPEs). In this work we explore high-energy (∼MeV) electron irradiation as a means to generate stable SPEs in hBN. We investigate four types of exfoliated hBN flakes - namely, high-purity multilayers, isotopically pure hBN, carbon-rich hBN multilayers and monolayered material - and find that electron irradiation increases emitter concentrations dramatically in all samples. Furthermore, the engineered emitters are located throughout hBN flakes (not only at flake edges or grain boundaries) and do not require activation by high-temperature annealing of the host material after electron exposure. Our results provide important insights into controlled formation of hBN SPEs and may aid in identification of their crystallographic origin

Community engagement in the prevention and control of COVID-19: Insights from Vietnam.

INTRODUCTION: Community engagement (CE) is an effective public health strategy for improving health outcomes. There is limited published knowledge about effective approaches to CE in ensuring effective responses to COVID-19 throughout lockdowns, travel restrictions and social distancing. In this paper, we contribute to bridging this gap by highlighting experience of CE in Vietnam, specifically focusing on migrant workers in Vietnam. METHODS: A cross-sectional qualitative study design was used with qualitative data collection was carried out during August-October 2020. Two districts were purposefully selected from two large industrial zones. Data was collected using in-depth interviews (n = 36) with individuals and households, migrants and owners of dormitories, industrial zone factory representatives, community representatives and health authorities. Data was analyzed using thematic analysis approach. The study received ethics approval from the Hanoi University Institutional Review Board. RESULTS: The government's response to COVID-19 was spearheaded by the multi-sectoral National Steering Committee for the Prevention and Control of COVID-19, chaired by the Vice Prime Minister and comprised different members from 23 ministries. This structure was replicated throughout the province and local levels and all public and private organizations. Different activities were carried out by local communities, following four key principles of infection control: early detection, isolation, quarantine and hospitalization. We found three key determinants of engagement of migrant workers with COVID-19 prevention and control: availability of resources, appropriate capacity strengthening, transparent and continuous communication and a sense of trust in government legitimacy. DISCUSSION AND CONCLUSION: Our results support the current literature on CE in infection control which highlights the importance of context and suggests that future CE should consider five key components: multi-sectoral collaboration with a whole-of-community approach to strengthen governance structures with context-specific partnerships; mobilization of resources and decentralization of decision making to encourage self-reliance and building of local capacity; capacity building through training and supervision to local institutions; transparent and clear communication of health risks and sensitization of local communities to improve compliance and foster trust in the government measures; and understanding the urgent needs ensuring of social security and engaging all parts of the community, specifically the vulnerable groups

COVID-19 Stressors on Migrant Workers in Vietnam: Cumulative Risk Consideration.

This study explored the impact of COVID-19 on migrant workers in Vietnam, using a cumulative risk assessment (CRA) framework which comprises four domains (workplace, environment, individual and community). A cross-sectional study was conducted. Data were collected in 2020 through a self-administered questionnaire with 445 domestic migrant workers in two industrial zones in two northern provinces (Bac Ninh and Ninh Binh) in Vietnam. The majority of migrant workers were female (65.2%), aged between 18 and 29 years old (66.8%), and had high school or higher education level qualifications. Most migrant workers had good knowledge about preventive measures (>90%) and correct practices on COVID-19 prevention (81.1%). Three health risk behaviors were reported: 10% of participants smoked, 25% consumed alcohol and 23.1% were engaged in online gaming. In terms of workplace, occupational working conditions were good. Noise was the most commonly reported hazard (29%). Regarding environment, about two-thirds of migrant workers lived in a small house (<36 m2). Most participants (80.4%) lived with their families. About community domain, many reported low salary or losing their job during January-July, 2020. Most migrants received information about COVID-19. The migrant workers suffered from poor health and low occupational safety, fear of job loss and income cut, poor housing and living conditions and limited access to public services. The holistic approach to address stressors is recommended to improve health and safety of migrant workers

ẢNH HƯỞNG CỦA CÔNG NGHỆ THỰC TẾ ẢO TĂNG CƯỜNG ĐẾN Ý ĐỊNH MUA HÀNG TRỰC TUYẾN CỦA NGƯỜI TIÊU DÙNG

The study shows the effects of factors affecting consumers' purchase intention after experiencing Virtual Try-on (VTO) in Vietnam. The study is carried out by quantitative method through data from 408 subjects of different ages in Hanoi and Northern provinces. The findings of the study demonstrate that perceived usefulness, perceived ease of use, perceived enjoyment, and perceived privacy risk, have a significant impact on users' attitudes toward Virtual Try-On (VTO). Consequently, these factors increase their influence on customers' purchase intentions. Based on these results, the research group recommends that, in practical settings, enterprises concentrate on providing high-quality services, promoting their products to augment the aforementioned factors, and simultaneously addressing users' attitudes to enhance the overall customer experience. Therefore, this study provides valuable insights into the factors that influence customers' attitudes toward VTO technology, thereby contributing to the existing literature on the topic.Nghiên cứu chỉ ra những tác động của các nhân tố ảnh hưởng tới ý định mua hàng của người tiêu dùng qua hành vi sử dụng công nghệ trải nghiệm sản phẩm trực tuyến (Virtual Try-on - VTO) tại Việt Nam. Phương pháp định lượng được sử dụng để phân tích dữ liệu từ 408 đối tượng trong nhiều độ tuổi khác nhau trên địa bàn thành phố Hà Nội và các tỉnh thành phố miền Bắc. Kết quả cho thấy rằng các nhân tố như cảm nhận tính hữu ích, cảm nhận tính dễ sử dụng, cảm nhận tính thích thú, và cảm nhận rủi ro về quyền riêng tư có tác động đến thái độ của người dùng với công nghệ VTO từ đó gia tăng ảnh hưởng tới ý định mua sắm của khách hàng. Nhóm nghiên cứu đề xuất rằng, trong bối cảnh thực tiễn, doanh nghiệp cần tập trung vào cung cấp dịch vụ chất lượng, quảng bá sản phẩm để nâng cao các yếu tố đã được đề cập, đồng thời quan tâm đến thái độ của người dùng để cải thiện trải nghiệm tích cực cho khách hàng

A potential low cost medium for cultivation of Dunaliella salina DCCBC15 in Vietnam

Dunaliella salina is a marine alga with high potential for beta-carotene (pro-vitamin A), up to more than 10% of cellular dry weight under appropriate stress conditions of limiting one of the following nutrients: nitrogen, phosphate, high light or high salt. Obtaining high biomass in low cost medium is the essential step of the two-phase culture system for beta-carotene production. For future development of beta-carotene production from Dunaliella in Vietnam, it is our first step to study a low cost medium using natural seawater enriched with industrial fertilizer N-P-K (30-15-10) commercially available in Vietnam. The primary results of biomass, cell density, chlorophyll a as well as growth rate are very promising to use this medium for mass culture of Dunaliella salina. The medium is recommended for growing other marine algae as well