Study on the Sintering and Mg Composition Effect on MgB2 Superconducting Bulks and Wires Synthesized by Powder-in-Sealed-Tube Method

Numerous research efforts aimed at the MgB2 (Magnesium diboride) as a superconducting material due to its higher critical temperature than Nb-based superconductors such as NbTi, Nb3Sn. Nowadays MgB2 is becoming more popular as the candidate to be applied on medical devices and large-scale applications because of its full coherence lengths, improved critical current density and fields, and simple crystal structure. In this study, we fabricated the 4 mm MgB2 superconducting wires by mixing stoichiometric mole ratio of Mg: B with 1.0:2.0 and 1.1:2.0 through the Powder-In-Sealed-Tube (PIST) method to optimize high critical temperature (TC) than the conventional MgB2 bulk and wire. Furthermore, we decreased the diameter of 4 mm to 1.8 mm wire and analyze the effect of critical temperature. The specimens were sintered at a different temperature to investigate the sintering effect of MgB2 superconducting wire. The resistivity versus temperature relationship, surface morphology, and crystal phase was characterized using Cryogenic system, SEM (Scanning Electron Microscopy), and XRD (X-ray Diffractometer), respectively. We optimized the high Tc,onset for the bulk and 4 mm wire compared to other studies that are 42.1K and 40.3K respectively at 800°C sintered temperature. Finally, the results suggest that the stoichiometric ratio of MgB2 exhibited excellent feasibility to prepare conventional MgB2 superconducting wire.

Has Korean growth become greener? Spatial econometric evidence for energy use and renewable energy

Using province-level data for South Korea, we analyze the dynamic relationship between economic growth and several energy parameters. Specifically, we decompose the growth effect into scale, composition, and technique effects, and control for regional spillovers through the use of a dynamic GMM estimator for spatial panel data models. The analyzed period, ranging from 2000 to 2017, allows us to look for changes in the regional growth effects following the implementation of the National Strategy for Green Growth in 2009. Our estimates show that the scale and composition effect tended to increase both per capita final energy use and energy intensity, outweighing reductions through the technique effect. In contrast, when considering renewable energy production, the scale and technique effect increased and the composition effect decreased the corresponding figures. Thereby, the technique effect was the main driver of increases in renewable energy production. Despite the larger, yet comparatively small share of renewables in Korea’s energy mix, no considerable change of the growth effects can be observed since 2009. Therefore, to reduce the risks for the economy and achieve the political objectives of the green growth strategy throughout the whole country and in a timely manner, a stronger commitment seems to be required.

International Trade, CO2 Emissions and Re-examination of “Pollution Haven Hypothesis” in China

We use input–output analysis and Levinson’s structural decomposition method to measure China’s CO2 emissions under the no-trade hypothesis, to calculate how international trade affects China’s emissions. We also analyze the driving factors of the difference between hypothetical no-trade CO2 emissions and actual emissions and discuss the existence of “pollution haven hypothesis” (PHH) in China. The results show that (1) from 2000 to 2017, the hypothetical no-trade CO2 emissions are 2.43–14.67% lower than actual emissions. The scale effect is the main cause of this difference, while the composition effect fluctuates and has little impact. (2) Although exports make other economies’ CO2 emissions transfer to China, imports also help avoid China’s emissions from some carbon-intensive sectors. (3) International trade has little impact on the cleanliness of China’s industry composition. The no-trade industry composition is slightly cleaner than the actual one before 2010, after which trade improves the cleanliness of industry composition to a small extent. PHH is invalid for China in recent years, and results for most developing countries do not support PHH. (4) The relationship between no-trade effects and income per capita for all the economies does not also support PHH. Most economies reduce emissions, and their industry compositions are cleaner because of trade, regardless of their development degree.

Decomposing public-private teachers’ wage gap: evidence from Brazil

A two-stage wage gap decomposition permits measuring the contribution of observableand unobservable characteristics of the wage gap formation and evolution comparingteachers’ earnings in the public and private sectors from 2006 to 2017. Teachers fromthe public sector earn more than the ones from the private sector at mean, median, andquantile 10 due to the composition effect. The analysis across levels of education showsthat the composition effect is important in explaining the wage gap in early childhoodeducation while the structure effect is more relevant to the wage gap decomposition inprimary and high school education.

How Strikes Can Arise: Sequences of Interaction in the Genesis of a Total Strike in Madrid Underground

Workers’ responses to austerity measures during the Great Recession were multiple and diverse. When and why they opted for contentious collective actions instead of reluctant acquiescence is still a subject of debate. In this article, I revisit the issue by examining the genesis of a total strike in Madrid Underground in June 2010, which occurred in response to a wage cut applied to this publicly owned enterprise. By drawing upon union communica-tions produced at the time of the events and semi-directive inter-views conducted with union representatives and ordinary workers, I retrace the sequences of interaction between workers, unions, the company management, and the regional government, which even-tually led to the total strike. The findings reveal that the question of ‘how’ is as important as the ‘why’: the relationship between the wage cut and the strike is in fact anything but direct. Rather, the strike resulted from a largely unintended ‘composition effect’–a combination of nested interactions between multiple and inter-dependent players.