Abstract. We describe a new and more efficient algorithm for checking universality and language inclusion on nondeterministic finite word automata (NFA) and tree automata (TA). To the best of our knowledge, the antichain-based approach proposed by De Wulf et al. was the most efficient one so far. Our idea is to exploit a simulation relation on the states of finite automata to accelerate the antichain-based algorithms. Normally, a simulation relation can be obtained fairly efficiently, and it can help the antichain-based approach to prune out a large portion of unnecessary search paths. We evaluate the performance of our new method on NFA/TA obtained from random regular expressions and from the intermediate steps of regular model checking. The results show that our approach significantly outperforms the previous antichain-based approach in most of the experiments.

Driven by the urgent demand of detecting trace amounts of pentachlorophenol (PCP) in contaminative water, a label-free immunosensor with ultra sensitivity and high selectivity was constructed based on a hybrid CdSe(x)Te(1-x) (0 ≤ x ≤ 1) nanocrystal (NCs)-modified TiO(2) nanotube (NT) arrays for the first time. The CdSe(x)Te(1-x) NCs were photoelectrodeposited on inner and outer space of the TiO(2) NTs, leading to high photoelectrical conversion efficiency in the visible region. PCP antibodies are covalently conjugated on the TiO(2) NTs due to the large surface area and good biocompatibility. Since the photocurrent is highly dependent on the TiO(2) surface properties, the specific interaction between PCP and the antibodies results in a sensitive change in the photocurrent, with a limit of detection (LOD) of 1 pM. High sensor-to-sensor reproducibility is achieved. The sensor was applied for the direct analysis of river water samples.

by judiciously adjusting the structure of ILs. ILs have been intensively studied as a "green" alternative to organic solvents for synthesis, catalysis, extraction, and separation. [2] They are also safe and versatile electrolytes for electrochemistry and energy-related applications. [3] However, their viscosities are generally two or three orders of magnitude higher than those of conventional organic solvents (molecular liquids), which inevitably lead to handling difficulties (e.g., infiltration, decantation, and dissolution), low reaction rates, competitive unimolecular side reactions, sluggish ionic transport, and significantly reduced ionic conductivity. [4] For the potential application of ILs, such high viscosities have to be deliberately avoided by choosing alternative anions such as bis (trifluoromethanesulfonimide) (TFSI − ) and dicyanamide anions with high charge delocalization [4b,5] or introducing ether groups that pack less efficiently and provide more available free volume to enable low viscosity. [6] Nevertheless, the disadvantageous high viscosities of ILs can become advantageous for special applications that require viscous materials, such as adhesion, sealing, and gelation. [7] Particularly, adhesion is the attraction between two different condensed phases when they are in contact to construct a robust joint. Adhesion involves not only the molecular interactions at the interface of two individual surfaces but also the energy within the deformed material when pulling them apart. Adhesives have been acknowledged as indispensable chemicals in daily life and in many industries ranging from packaging, labeling, housing construction, and automobile manufacturing to soft robots, wearable devices, and aerospace. [7a,b,8] Along with conventional resins and gum-based adhesives, many musselinspired and catechol-based polymeric materials had been developed as modern adhesives in the past. [9] Nevertheless, they possess inherent drawbacks such as irreversible oxidizing crosslinking, tedious synthesis, and poor cycling performance. [10] We recently reported a series of noncatechol adhesive materials produced by water-triggered supramolecular polymerization of crown ether-containing monomers, but the synthesis of such specific monomers involves complicated functionalization, which is difficult to scale up. [11] The presence of water in these supramolecular adhesives also becomes an obvious disadvantage as they cannot bear ultra-high vacuum adhesion.Adhesive materials have wide applications in diverse fields, but the development of a novel and multipurpose adhesive is a great challenge. This study demonstrates that conventional poly(ionic liquid)s (PILs) can be designed as highly efficient adhesives by simply introducing alkoxy moieties into the cationic backbone of PILs containing bis(trifluoromethanesulfonimide) (TFSI − ) anions. The incorporated flexible alkoxy chain not only reduces the glass transition temperature of PILs but also endows these materials with strong hydrogen bonding interactions, w...

We present a decision procedure for a logic that combines (i) word equations over string variables denoting words of arbitrary lengths, together with (ii) constraints on the length of words, and on (iii) the regular languages to which words belong. Decidability of this general logic is still open. Our procedure is sound for the general logic, and a decision procedure for a particularly rich fragment that restricts the form in which word equations are written. In contrast to many existing procedures, our method does not make assumptions about the maximum length of words. We have developed a prototypical implementation of our decision procedure, and integrated it into a CEGAR-based model checker for the analysis of programs encoded as Horn clauses. Our tool is able to automatically establish the correctness of several programs that are beyond the reach of existing methods.