Abstract: Implementations of this specification provide query optimization methods, apparatuses, and systems for secure multi-party databases. In an implementation, a method includes: receiving a current query associated with a plurality of target database of a multi-party database system, generating a plurality of execution plans for the current query, determining, for each execution plan, a respective cost computation formula of a plurality of cost computation values for computing an execution cost of jointly executing the execution plan by the plurality of target databases, receiving a secure computation result from each of a plurality of query engines corresponding to the plurality of target databases, and determining an optimal execution plan having a lowest cost value in the plurality of cost computation formulas based on the secure computation result.

Abstract: The present disclosure provides a display substrate, a preparing method thereof, and a display device. The display substrate includes: a base substrate including a spacing region; a plurality of light-emitting device groups on the base substrate, any two adjacent light-emitting device groups of the plurality of light-emitting device groups being spaced apart from each other by the spacing region; and a light-shielding layer on the base substrate. The light-shielding layer covers the plurality of light-emitting device groups and fills the spacing region, a first portion of the light-shielding layer covering the plurality of light-emitting device groups has a first thickness, a second portion of the light-shielding layer filling the spacing region has a second thickness, the first thickness is less than the second thickness.

Abstract: Disclosed is a liquid-phase oxidative decomposition method for radioactively contaminated carbonaceous material, providing a method of oxidizing carbon into a gas in liquid phase to treat radioactively contaminated carbonaceous material. The method comprises the following steps: ball milling a mixture of a molybdenum-containing substance and a carbonaceous material, thermally treating the ball milled mixture, and performing liquid-phase oxidation of the thermally treated mixture. The thermal treatment causes carbon to enter space between molybdenum atoms so as to reduce the particle size of carbon and improve the chemical reactivity of carbon, and an oxidant is then used to oxidize the carbon in the space between molybdenum atoms into a gas in liquid phase, while the molybdenum-containing moiety is converted into a water-soluble substance.

Abstract: Disclosed is a liquid-phase oxidative decomposition method for radioactively contaminated carbonaceous material, providing a method of oxidizing carbon into a gas in liquid phase to treat radioactively contaminated carbonaceous material. The method comprises the following steps: ball milling a mixture of a molybdenum-containing substance and a carbonaceous material, thermally treating the ball milled mixture, and performing liquid-phase oxidation of the thermally treated mixture. The thermal treatment causes carbon to enter space between molybdenum atoms so as to reduce the particle size of carbon and improve the chemical reactivity of carbon, and an oxidant is then used to oxidize the carbon in the space between molybdenum atoms into a gas in liquid phase, while the molybdenum-containing moiety is converted into a water-soluble substance.