Estimating environmental efficiency of the selected Asian countries: does convergence exist?

Environmental degradation has attained much attention from researchers and policymakers at national and global levels. The ever-increasing energy use in production methods is considered one of the fundamental reasons for environmental degradation. The concept of environmental efficiency in the wake of sustainable growth evolved in the last three decades. The present study has been designed to estimate environmental efficiency using the Malmquist-Luenberger productivity index (MLI) using annual data from 43 Asian countries from 1990 to 2019. The MLI is an established econometric approach to estimate cases where input variables are used to get output variables in desirable and undesirable forms. Labor, capital, and energy consumption are input variables, while carbon dioxide (CO2) emissions (undesirable variable) and gross domestic product (undesirable variable) are taken as output variables. The results suggested that, on average, environmental efficiency has decreased by 0.3% over the period in selected Asian countries. Cambodia, Turkey, and Nepal have the highest total factor productivity (TFP) output growth rate on average among 43 Asian countries. These countries are excellent examples of sustainable development that balances environmental protection and efficiency. On the other hand, Kuwait, Mongolia, and Yemen showed the least TFP growth. The study also employed unconditional and convergence tests where the countries' conditional convergence is based on foreign direct investment, population density, inflation, industrialization, and globalization. Some policy implications for Asian countries are also discussed at the end of the study.

Natural convection flow of a second grade fluid in an infinite vertical cylinder.

In current study natural convection flow of second grade fluid in an oscillating infinite vertical cylinder is investigated. The dimensionless governing equations for temperature and velocity are obtained by introducing the non-dimensional variables. Exact solutions for temperature and velocity field are computed by means of integral transformation. Solutions for cosine and sine oscillations of velocity field are introduced in the form of transient and post-transient arrangements. A special case for Newtonian fluid is obtained from general results and transients solutions are computed in terms of tables. In the end, the impact of dimensionless numbers (Grashof and Prandtl numbers) at different values of time is presented in graphical form and found that velocity for Newtonian fluid has greater values than the second grade fluid. Furthermore, there are some comparisons of calculated solutions with existing solutions in literature.

Wafer-Scale Synthesis of Semiconducting SnO Monolayers from Interfacial Oxide Layers of Metallic Liquid Tin.

Atomically thin semiconductors are one of the fastest growing categories in materials science due to their promise to enable high-performance electronic and optical devices. Furthermore, a host of intriguing phenomena have been reported to occur when a semiconductor is confined within two dimensions. However, the synthesis of large area atomically thin materials remains as a significant technological challenge. Here we report a method that allows harvesting monolayer of semiconducting stannous oxide nanosheets (SnO) from the interfacial oxide layer of liquid tin. The method takes advantage of van der Waals forces occurring between the interfacial oxide layer and a suitable substrate that is brought into contact with the molten metal. Due to the liquid state of the metallic precursor, the surface oxide sheet can be delaminated with ease and on a large scale. The SnO monolayer is determined to feature p-type semiconducting behavior with a bandgap of ∼4.2 eV. Field effect transistors based on monolayer SnO are demonstrated. The synthetic technique is facile, scalable and holds promise for creating atomically thin semiconductors at wafer scale.