Foreign-Funded Enterprises and Pollution Halo Hypothesis: A Spatial Econometric Analysis of Thirty Chinese Regions

China is one of the world’s major environmental polluters, therefore, Chinese environmental efficiency is an issue of global importance. In this study, we aim to identify economic factors affecting environmental efficiency scores in different regions of China from a spatial econometric perspective. We measure environmental efficiency scores, relative to the theoretically consistent production possibilities frontier estimated, according to a novel iterative methodology. As expected, we find that environmental efficiency scores are negatively affected by the prevalence of heavy industry sector in the economy, with a higher share of coal as a source of energy exacerbating the problem. We also find evidence that strongly support the pollution halo hypothesis, which credits foreign-funded enterprises with producing in a more environmentally-friendly way. Surprisingly, we find a negative association between the share of tertiary sectors in a regional economy and environmental efficiency—emphasizing the need to address the indirect effects produced on the environment by the seemingly innocuous sectors, such as the hotel sector. We encourage the creation of foreign-funded enterprises, and support formulating environmental protection policies that consider the indirect effects various economic sectors have on the environment

Artificial Engine Sound Synthesis Method for Modification of the Acoustic Characteristics of Electric Vehicles

Sound radiation from electric motor-driven vehicles is negligibly small compared to sound radiation from internal combustion engine automobiles. When running on a local road, an artificial sound is required as a warning signal for the safety of pedestrians. In this study, an engine sound was synthesized by combining artificial mechanical and combustion sounds. The mechanical sounds were made by summing harmonic components representing sounds from rotating engine cranks. The harmonic components, including not only magnitude but also phase due to frequency, were obtained by the numerical integration method. The combustion noise was simulated by random sounds with similar spectral characteristics to the measured value and its amplitude was synchronized by the rotating speed. Important parameters essential for the synthesized sound to be evaluated as radiation from actual engines were proposed. This approach enabled playing of sounds for arbitrary engines. The synthesized engine sounds were evaluated for recognizability of vehicle approach and sound impression through auditory experiments

Cost-Benefit Analysis of Seawalls in South Korea: A Bottom-Up Assessment

<p>We present a cost-benefit analysis of coastal protection via seawalls in South Korea against climate-change-induced sea level rise. This is the first bottom-up analysis for South Korea, deriving the optimal solution from extensive geographical and financial databases with detailed street-address-level information. Our analysis indicates that the net benefit is maximized if seawalls are built along 21% of the South Korean coast. By comparing the bottom-up solution to the aggregate solution and utilizing a comprehensive sensitivity analysis, we highlight two implications for the climate change economics literature. First, the country-level aggregate analysis adopted by many existing studies may include a sizable aggregation bias. Second, relative to the climate change mitigation problem, the coastal protection problem is less sensitive to the choice of the discount rate.</p

Photomultiplication‐Type Organic Photodetectors with High EQE‐Bandwidth Product by Introducing a Perovskite Quantum Dot Interlayer

A photomultiplication (PM)-type organic photodetector (OPD) that exploits the ionic motion in CsPbI3 perovskite quantum dots (QDs) is demonstrated. The device uses a QD monolayer as a PM-inducing interlayer and a donor-acceptor bulk heterojunction (BHJ) layer as a photoactive layer. When the device is illuminated, negative ions in the CsPbI3 QD migrate and accumulate near the interface between the QDs and the electrode; these processes induce hole injection from the electrode and yield the PM phenomenon with an external quantum efficiency (EQE) >2000% at a 3 V applied bias. It is confirmed that the ionic motion of the CsPbI3 QDs can induce a shift in the work function of the QD/electrode interface and that the dynamics of ionic motion determines the response speed of the device. The PM OPD showed a large EQE-bandwidth product >10(6) Hz with a -3 dB frequency of 125 kHz at 3 V, which is one of the highest response speeds reported for a PM OPD. The PM-inducing strategy that exploits ionic motion of the interlayer is a potential approach to achieving high-efficiency PM OPDs.11Nsciescopu

Latent and controllable doping of stimuli-activated molecular dopants for flexible and printable organic thermoelectric generators

Conjugated polymers (CPs) are a promising class of materials for organic thermoelectric generators (OTEGs); however, achieving high electrical conductivity through molecular doping while maintaining compatibility with thin-film printing processes remains a huge challenge. In this paper, we present a novel doping strategy using stimuli-activated molecular dopants (SAMDs) based on photoacid generators (PAGs) that can be activated by light of a specific wavelength. We demonstrate that this approach can effectively control the doping efficiency and optoelectronic properties of CP-PAG-blended thin films, resulting in a wide range of electrical conductivities. Our selected PAG molecules enabled efficient printing of the CP-PAG mixed solution and yielded a high thermoelectric figure of merit. To elucidate the mechanism behind this high thermoelectric performance, we systematically investigated the morphologies, microstructures, and energy structures of the PAG-doped CP thin films and performed various comparative tests. We also demonstrate the feasibility of using SAMDs to print flexible OTEG modules on thin polyimide substrates. We believe that our work represents a significant step toward the development of efficient, scalable, and sustainable thermoelectric devices for power generation and waste heat recovery, and highlights the advantages of PAG-based SAMDs for printable organic thermoelectrics

Investigating heterogeneous defects in single-crystalline WS2 via tip-enhanced Raman spectroscopy

© 2022 Springer Nature Limited. Nanoscale defects in two-dimensional (2D) transition metal dichalcogenides (TMDs) alter their intrinsic optical and electronic properties, and such defects require investigation. Atomic-resolution techniques such as transmission electron microscopy detect nanoscale defects accurately but are limited in terms of clarifying precise chemical and optical characteristics. In this study, we investigated nanoscale heterogeneous defects in a single-crystalline hexagonal WS2 monolayer using tip-enhanced Raman spectroscopy (TERS). We observed the Raman properties of heterogeneous defects, which are indicated by the shifted A(1)&apos;(Gamma) modes appearing on the W- and S-edge domains, respectively, with defect-induced Raman (D) mode. In the edge region, various Raman features occur with nanoscale defects. In addition, the TERS signals from single-crystalline WS2 indicate the existence of two majority defects in each domain, which imply S- and W-dominated vacancies. Quantum mechanical computations were performed for each majority defect and demonstrated the defect-induced variation in the vibrational phonon modes. TERS imaging promises to be a powerful technique for determining assorted nanoscale heterogeneous defects as well as for investigating the properties of other nanomaterials.11Nsciescopu