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Control of metal cation distribution in layered double hydroxide for enhanced oxygen evolution reaction
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Greenhouse gas emissions, firm value, and the investor base: Evidence from Korea
No full textThis paper examines the association between greenhouse gas (GHG) emissions, firm value and foreign ownership for Korean firms. In Korea, firms that emit GHG more than a given threshold have been mandated to disclose the levels of GHG emissions since 2011. We find that firms bound to disclose GHG emissions are likely to be valued less compared to firms without disclosure obligations. In addition, foreign investors' ownership is lower for mandatory-disclosure firms than firms without such requirements. Among mandatory-disclosure firms, GHG intensity is negatively associated with firm value and this association is strengthened after 2015, following the Paris Accords
Stability of Cr oxide formed on Fe-20Cr-2Si alloy in 1200 degrees C steam or oxygen
No full textFe-20Cr-2Si alloy, proposed as a high-temperature oxidation barrier for accident-tolerant fuel cladding in light water reactors, maintained oxidation resistance at 1200 degrees C under Ar-50%H2O and Ar-20%O2 environments for up to 24 h. However, Cr2O3 on the Fe-20Cr-2Si alloy volatilized above 1000 degrees C, degradation started under Ar20%O2, and voids were observed at the metal/oxide interface. These were attributed to the copious formation of volatile species owing to the high oxygen partial pressure in Ar-20%O2. Thus, more vacancies were generated and moved to the metal/oxide interface. Contrastingly, degradation was not initiated under Ar-50%H2O, indicating sufficient resistance of Fe-20Cr-2Si to highly oxidizing environments
Design of Pore Properties of an Al-Based Metal-Organic Framework for the Separation of an Ethane/Ethylene Gas Mixture via Ethane-Selective Adsorption
No full textA series of Al-based isomorphs (CAU-10H, MIL-160, KMF-1,and CAU-10pydc)were synthesized using isophthalic acid (ipa), 2,5-furandicarboxylicacid (fdc), 2,5-pyrrole dicarboxylic acid (pyrdc), and 3,5-pyridinedicarboxylicacid (pydc), respectively. These isomorphs were systematically investigatedto identify the best adsorbent for effectively separating C2H6/C2H4. All CAU-10 isomorphs exhibitedpreferential adsorption of C2H6 over that ofC(2)H(4) in mixture. CAU-10pydc exhibited the bestC(2)H(6)/C2H4 selectivity(1.68) and the highest C2H6 uptake (3.97 mmolg(-1)) at 298 K and 1 bar. In the breakthrough experimentusing CAU-10pydc, 1/1 (v/v) and 1/15 (v/v) C2H6/C2H4 gas mixtures were successfully separatedinto high-purity C2H4 (>99.95%), with remarkableproductivities of 14.0 L-STP kg(-1) and32.0 L-STP kg(-1), respectively, at 298K. Molecular simulations revealed that the exceptional separationperformance of CAU-10pydc originated from the increased porosity andreduced electron density of the pyridine ring of pydc, leading toa relatively larger decrease in pi-pi interactionswith C2H4 than in the C-H center dot center dot center dot pi interactions with C2H6. This study demonstratesthat the pore size and geometry of the CAU-10 platform are modulatedby the inclusion of heteroatom-containing benzene dicarboxylate orheterocyclic rings of dicarboxylate-based organic linkers, therebyfine-tuning the C2H6/C2H4 separation ability. CAU-10pydc was determined to be an optimum adsorbentfor this challenging separation
Revealing the Molecular Weight Effect on Highly Efficient Polythiophene Solar Cells
No full textPolythiophenes (PTs) are promising electron donors inorganic solarcells (OSCs) due to their simple structures and excellent syntheticscalability. Benefiting from the rational molecular design, the powerconversion efficiency (PCE) of PT solar cells has been greatly improved.Herein, five batches of the champion PT (P5TCN-F25) with molecularweights ranging from 30 to 87 kg mol(-1) were prepared,and the effect of the molecular weight on the blend film morphologyand photovoltaic performance of PT solar cells was systematicallyinvestigated. The results showed that the PCEs of the devices improvedfirst and then maintained a high value with the increase of molecularweight, and the highest PCE of 16.7% in binary PT solar cells wasobtained. Further characterizations revealed that the promotion inphotovoltaic performance mainly comes from finer phase separationstructures and more compact molecular packing in the blend film. Thebest device stabilities were also achieved by polymers with high molecularweights. Overall, this study highlights the importance of optimizingthe molecular weight for PTs and offers directions to further improvethe PCE of PT solar cells
Non-asymptotic estimates for TUSLA algorithm for non-convex learning with applications to neural networks with ReLU activation function
No full textWe consider nonconvex stochastic optimization problems where the objective functions have super-linearly growing and discontinuous stochastic gradients. In such a setting, we provide a nonasymptotic analysis for the tamed unadjusted stochastic Langevin algorithm (TUSLA) introduced in Lovas et al. (2020). In particular, we establish nonasymptotic error bounds for the TUSLA algorithm in Wasserstein-1 and Wasserstein-2 distances. The latter result enables us to further derive nonasymptotic estimates for the expected excess risk. To illustrate the applicability of the main results, we consider an example from transfer learning with ReLU neural networks, which represents a key paradigm in machine learning. Numerical experiments are presented for the aforementioned example, which support our theoretical findings. Hence, in this setting, we demonstrate both theoretically and numerically that the TUSLA algorithm can solve the optimization problem involving neural networks with ReLU activation function. Besides, we provide simulation results for synthetic examples where popular algorithms, e.g., ADAM, AMSGrad, RMSProp and (vanilla) stochastic gradient descent algorithm, may fail to find the minimizer of the objective functions due to the super-linear growth and the discontinuity of the corresponding stochastic gradient, while the TUSLA algorithm converges rapidly to the optimal solution. Moreover, we provide an empirical comparison of the performance of TUSLA with popular stochastic optimizers on real-world datasets, as well as investigate the effect of the key hyperparameters of TUSLA on its performance
Preparation of multiferroic lead iron niobate thin film with low crystallization temperature via sol-gel method using monoethanolamine
No full textThis study reports the synthesis of a multiferroic lead iron niobate (PbFe1/2Nb1/2O3, PFN) thin film with a low crystallization temperature using monoethanolamine (MEA) as a chelating agent via a sol-gel method. The results revealed that the presence of MEA led the Nb precursor to react at similar to 150 degrees C instead of 325-350 degrees C, thus indicating that the Nb precursor reacted first with the Fe precursor rather than the Pb precursor. Furthermore, X-ray diffraction patterns revealed that the addition of MEA allowed the PFN thin films to be sintered as a single phase at low temperatures (similar to 500 degrees C), while this can be only achieved at temperatures above 800 degrees C in the absence of MEA. The scanning electron microscope images revealed that the obtained PFN thin film was uniformly coated on the SiO2/Si substrate both in the absence and presence of MEA. Consequently, the presence of MEA can broaden the application scope of PFN thin films in photovoltaic devices
Good for Us? Good for Me? Government Intervention for Sustainability and Service Quality
No full textKorean government???s recent policy prohibits lodging properties from offering disposable hotel amenities including shampoo, soaps, and toothbrushes. Lodging businesses in Korea have been forced to either remove amenities or offer substitutes. Government policies for social and environmental sustainability often force businesses to cease existing services and offer substitutes, which is likely to harm service quality and customer satisfaction. Therefore, the business needs to understand how customers respond to such interventions and possible service quality declines. This study examines whether and how types of substitutes (i.e., perfect substitutes, imperfect substitutes, and no substitutes) that a hotel provides to comply with the government sustainability policy influence customers??? policy acceptance and customer satisfaction with the service. We also propose that the influence of substitute types on customer satisfaction and policy acceptance be moderated by the communication messages of the hotel. More specifically, we employ regulatory focus theory to develop the communication message frame, namely prevention hope and promotion hope. Our results show that consumers offered perfect substitutes have greater policy acceptance and higher satisfaction than those offered imperfect substitutes and no substitutes. Interestingly, however, no significant differences in satisfaction and policy acceptance are found between imperfect substitutes and no substitute groups. In terms of communication messages, a message with a promotion hope frame is more effective than a prevention hope message to improve the satisfaction of the incomplete substitute group, while no significant differences in satisfaction between the two message frames are found for perfect substitutes and no substitute groups. With the findings, we provide meaningful insights into how businesses respond to government intervention for sustainability and offer useful managerial implications