The impact of online education on carbon emissions in the context of the COVID-19 pandemic - Taking Chinese universities as examples.

While the COVID-19 pandemic has had various impacts on economic and social development, it may have partially reduced human energy use, thereby helping achieve the goals of reducing carbon emissions and promoting carbon neutrality. During the pandemic, online education was widely used to replace traditional education all over the world. There is a lack of empirical studies on whether and to what extent the change of education model can reduce carbon emissions. Taking Chinese universities as cases, this study, concentrating on two main elements - transportation and electricity consumption - constructs a model and calculates the impact of online education on carbon emissions. The results show that online education can significantly reduce energy consumption and lower carbon emissions. In the field of higher education alone, the carbon emissions reduction caused by online education in half a year is equivalent to the total carbon emissions reduction of college students caused by online education during the half-year is equivalent to the total carbon emissions in 1.296 h in China, 2.688 h in the United States, 5.544 h in India, 12 h in Japan and 3.864 h in European countries of OECD. Therefore, this study suggests that the impact of online education on carbon emissions should be further studied, online education should be promoted through legislation and other systemic measures, and the goals of carbon emissions and carbon neutrality should be explored further within the field of education.

Enhancing the Efficiency of Graphene Oxide Reduction in Low-Power Digital Video Disc Drives by a Simple Precursor Heat Treatment.

Laser reduction of graphene oxide (GO) produces graphene effectively. As a low-power laser source, commercial digital video disc (DVD) drives provide a versatile platform to produce reduced graphene films in designed 2D patterns. However, research on how GO characteristics affect its laser reduction efficiency in DVD drives is rarely conducted. Here, we investigate how heating the GO dispersion affects the photoreduction process of GO films in a LightScribe DVD drive. Without noticeably changing the oxygen content, such mild heat treatment significantly improves GO's absorption in the visible region, resulting in significant enhancement on GO's laser reduction efficiency. We demonstrate that the laser reduction efficiency increases with the increasing treatment time. The enhanced reduction level greatly improves the performance of laser-scribed graphene electrodes in applications such as glucose sensors (with an optimal linear response range up to 2550 µM) and supercapacitors (with an optimal areal capacity of 1.37 mF cm-2 at the scan rate of 50 mV s-1). This proposed approach provides general insights into the production of laser-reduced graphene with low-power laser sources, for advanced device applications such as wearable electronics and flexible microelectronics.

A flexible and highly sensitive nonenzymatic glucose sensor based on DVD-laser scribed graphene substrate.

Flexible and implantable glucose biosensors are emerging technologies for continuous monitoring of blood-glucose of diabetes. Developing a flexible conductive substrates with high active surface area is critical for advancing the technology. Here, we successfully fabricate a flexible and highly sensitive nonenzymatic glucose by using DVD-laser scribed graphene (LSG) as a flexible conductively substrate. Copper nanoparticles (Cu-NPs) are electrodeposited as the catalyst. The LSG/Cu-NPs sensor demonstrates excellent catalytic activity toward glucose oxidation and exhibits a linear glucose detection range from 1 µM to 4.54 mM with high sensitivity (1.518 mA mM-1 cm-2) and low limit of detection (0.35 µM). Moreover, the LSG/Cu-NPs sensor shows excellent reproducibility and long-term stability. It is also highly selective toward glucose oxidation under the presence of various interfering species. Excellent flexing stability is also demonstrated by the LSG/Cu-NPs sensor, which is capable of maintaining 83.9% of its initial current after being bent against a 4-mm diameter rod for 180 times. The LSG/Cu-NPs sensor shows great potential for practical application as a nonenzymatic glucose biosensor. Meanwhile, the LSG conductive substrate provides a platform for the developing next-generation flexible and potentially implantable bioelectronics and biosensors.