In this study, titanium oxide (TiO2) prepared via a solid-state electrochemical oxidation process was characterized and applied in photovoltaic devices employing a selenium light-absorbing layer with a bandgap of 1.9 eV, making it promising for indoor photovoltaic (IPV) applications. This process enables the oxidation of titanium metal thin films at relatively low temperatures, facilitating the formation of electron transport layers that may be suitable for future application to flexible substrates. The fabricated TiO2 thin films were employed as electron transport layers in selenium-based photovoltaic devices. Ultraviolet photoelectron spectroscopy (UPS), X-ray photoelectron spectroscopy (XPS), and transmittance spectroscopy revealed a conduction band offset of −0.42 to −0.47 eV with selenium, resulting in the formation of a cliff-type junction. This band alignment is comparable to that reported for sputter-deposited ZnMgO and TiO2 electron transport layers used in high-performance Se thin-film solar cells. Au/MoO3/p-Se/Te/n-TiO2/ITO photovoltaic devices achieved a power conversion efficiency of 3.5% after heat and light soaking treatment. These results demonstrate the feasibility of solid-state electrochemically oxidized TiO2 as an electron transport layer for selenium photovoltaics and establish solid-state electrochemical oxidation as a low-temperature and solvent-free fabrication route for future flexible optoelectronic devices.
Limb-trunk coordination plays an essential role in daily actions. The reticulospinal contribution in limb muscles has been suggested to be modulated by long-term motor experience, such as strength training. However, it remains unclear whether reticulospinal contributions in limb-trunk coordinated movements are modulated by strength training. This study aimed to determine whether reticulospinal contributions to limb-trunk coordination differ between strength-trained and untrained individuals. Fifteen long-term (≥3 yrs) strength-trained and 15 untrained healthy men participated in this study. Participants performed a rapid bilateral arm-curl task while standing, using a load corresponding to 35% of their one-repetition maximum, in response to visual, visual-auditory (80 dB), or visual-startling (115 dB) stimuli. Electromyography (EMG) was recorded from the right biceps brachii (BB) and erector spinae (ES) muscles during the task. In the visual-alone condition, ES activation occurred closer in time to BB onset in the trained group than in the untrained group, indicating tighter temporal coordination between the limb prime mover and trunk postural muscles in strength-trained individuals. In both groups, visual-startling stimuli shortened the EMG onset of both the BB and ES, suggesting reticulospinal contributions to both muscles. Notably, the relative reduction in EMG onset of the BB induced by the startling stimulus was smaller in the trained group than in the untrained group, whereas no difference between groups was observed for the ES. These findings suggest that strength training may modify limb-trunk muscle coordination during standing arm curls and may be associated with muscle-specific adaptations in reticulospinal contributions.
This paper establishes a uniform convergence result for a positive semi-definite modification of the Malliavin-Mancino Fourier estimator, designed for estimating the spot volatility process from high-frequency, non-synchronized data. The estimator, referred to as the PDF estimator, was previously introduced and its consistency in L2 was established. This work strengthens that result by proving the estimator's uniform convergence in probability together with its convergence rate. Under a set of assumptions concerning the regularity of the volatility process and the relationship between tuning parameters and observation frequency, we demonstrate that the proposed estimator converges uniformly to the true spot volatility process at any order strictly smaller than n−1/7 against the number of observations n in the general non-synchronized setting, provided the underlying process is a semimartingale. When the observations are in addition synchronous and equally spaced, the discretization error becomes orthogonal on the grid and the same analysis yields any order strictly smaller than n−1/4, which matches the optimal rate known for classical pointwise estimators; a global estimator thus attains, in the uniform topology, the accuracy hitherto established only pointwise. Since there has been no order estimates for the uniform convergence of a global estimator like Malliavin-Mancino's, these findings provide a stronger theoretical guarantee for the method, ensuring that the entire estimated volatility path closely approximates the true path as the observation density increases, which is a crucial property for applications in financial econometrics and risk management.
Renewable energy variability necessitates flexible demand-side management to maintain grid stability. Battery electric vehicles (BEVs) can serve as distributed energy resources through vehicle-to-grid (V2G) technology, yet realizing this potential depends critically on user acceptance of home-based discharging. This study investigates BEV users' preferences for home discharging behavior under V2G conditions, systematically comparing weekday and weekend contexts. Choice-based conjoint experiments were conducted with Japanese BEV owners, incorporating four attributes: discharging time slot, electricity selling price, current state of charge (SoC), and guaranteed minimum SoC. Results indicated that all four attributes influenced discharging decisions, with electricity selling price and time slot as the dominant factors. Weekday preferences were sharply concentrated in late evening and overnight periods, whereas weekend preferences were more evenly distributed. Scenario-based simulations using three identified user segments-Price driven, Balanced, and Time slot driven-showed that combining elevated electricity selling prices with higher current SoC during peak hours (17:00-24:00) raised their relative discharging probability by 47.1% on weekdays and 57.1% on weekends (17.6 and 19.8 percentage points) versus the low incentive case. Separate sensitivity analyses revealed electricity selling price as the primary lever and current SoC as a smaller, directionally consistent complement for shifting discharging preferences toward peak hours, both amplified on weekends across all segments. These findings provide a foundation for designing time-varying, day-type-differentiated, and segment-targeted V2G tariff structures that align user preferences for discharging behavior with grid flexibility needs, helping mitigate supply-demand imbalances from variable renewable energy integration.
This study explores value co-creation and co-destruction across the macro, meso, and micro levels of a service ecosystem by examining the development of Japan's donation system. Although service-dominant logic (SDL) has become a central framework in marketing, its application in public sector ecosystems remains limited. Similarly, some studies have addressed how value co-creation and co-destruction unfold interdependently in the context of an ecosystem. By analyzing the 15-year history of Japan's "hometown tax" donation system, this study reveals how reciprocal gifts, conceptualized as goods, expand the perceived value of donations, while simultaneously creating friction among stakeholders. As local governments sought to attract donations with increasingly appealing reciprocal gifts in the system, the central government viewed these practices as value-destructive, leading to regulatory interventions. The findings illustrate the intertwined relationship between value co-creation and co-destruction, underscoring the importance of institutional design and transformation not only for the diffusion of donation practices but also for the service ecosystem as a whole.
