Lead scandium tantalate (PbSc_0.5Ta_0.5O₃, PST) is one of the most promising ferroelectric materials for electrocaloric (EC) refrigeration because of the large enthalpy change (ΔH) at room temperature (RT), whose properties are determined by the ordering arrangement of two kinds of heterovalent ions in B-sites. The highly ordered PST ceramic always has excellent EC properties, while it is difficult to achieve. Besides, research on the modulation of ordering degree (Ω) in PST ceramics is still rare up to now, particularly regarding its impact on ferroelectric properties, phase transition characteristics, and electrocaloric effects. Thus, it is imperative to bridge this research gap.

The development of multifunctional composites with desired electromagnetic wave absorption and antibacterial performance for the medical field has aroused wide concern. In this work, SiOC/Ag composites were successfully fabricated via liquid phase method. When the filler content of SiOC/Ag-3 is 40 wt.%, SiOC/Ag-3 exhibits excellent electromagnetic wave absorption performance, achieving a minimum reflection loss value of -58.03 dB with a matching thickness of only 2.82 mm. The superior electromagnetic wave absorption performance is attributed to multiple reflections, conductive loss and interfacial polarization loss. Besides, the RCS simulation indicates all RCS values of PEC with SiOC/Ag-3 coating are below -20 dB·m² across the incident angle range from -60° to 60°, exhibiting strong radar stealth performance. Moreover, SiOC/Ag composites also achieve excellent antibacterial ability to E. coli and S.aureus by reactive oxygen species under visible light radiation. This work provides new insights into the design and development of bifunctional composites with electromagnetic wave absorption and antibacterial performance for application in medical devices.

Tianjin Normal University (Prof. Cheng-Peng Li) and Southeast Normal University (Prof. Yan-Qian Lan) have developed crystalline porous framework (CPF) composite beads to trap ⁹⁹TcO₄^– in nuclear wastewater. 1 g of beads processed 4.8 L of pre-treated simulated waste, with residual Tc levels reduced to 0.026 ppb—significantly below the WHO (0.159 ppb) and U.S. EPA (0.053 ppb) drinking water standards (calculated from nonradioactive surrogate ReO₄^–). This scalable strategy enables deep purification of trace radionuclide, enabling industrial deployment of nanoscale adsorbent technologies.

This work demonstrates the first realization of an in-orbit cold atom gyroscope using the China Space Station Atom Interferometer, representing the emergence of a space quantum inertial sensing epoch.This work demonstrates the first realization of an in-orbit cold atom gyroscope using the China Space Station Atom Interferometer, representing the emergence of a space quantum inertial sensing epoch.

Purpose

This paper provides a structural model to value startup companies and determine the optimal level of research and development (R&D) spending by these companies.

Design/methodology/approach

This paper describes a new variant of float-the-money options, which can act as a financial instrument for financing R&D expenses for a specific time horizon or development stage, allowing the investor to share in the startup's value appreciation over that duration. Another innovation of this paper is that it develops a structural model for evaluating optimal level of R&D spending over a given time horizon. The paper deploys the Gompertz-Cox model for the R&D project outcomes, which facilitates investigation of how increased level of R&D input can enhance the company's value growth.

Findings

The author first introduces a time-varying drift term into standard Black-Scholes model to account for the varying growth rates of the startup at different stages, and the author interprets venture capital's investment in the startup as a “float-the-money” option. The author then incorporates the probabilities of startup failures at multiple stages into their financial valuation. The author gets a closed-form pricing formula for the contingent option of value appreciation. Finally, the author utilizes Cox proportional hazards model to analyze the optimal level of R&D input that maximizes the return on investment.

Research limitations/implications

The integrated contingent claims model links the change in the financial valuation of startups with the incremental R&D spending. The Gompertz-Cox contingency model for R&D success rate is used to quantify the optimal level of R&D input. This model assumption may be simplistic, but nevertheless illustrative.

Practical implications

Once supplemented with actual transaction data, the model can serve as a reference benchmark valuation of new project deals and previously invested projects seeking exit.

Social implications

The integrated structural model can potentially have much wider applications beyond valuation of startup companies. For instance, in valuing a company's risk management, the level of R&D spending in the model can be replaced by the company's budget for risk management. As another promising application, in evaluating a country's economic growth rate in the face of rising climate risks, the level of R&D spending in this paper can be replaced by a country's investment in addressing climate risks.

Originality/value

This paper is the first to develop an integrated valuation model for startups by combining the real-world R&D project contingencies with risk-neutral valuation of the potential payoffs.