Image steganography based on intelligent devices is one of the effective routes for safely and quickly transferring secret information. However, optical image steganography has attracted far less ...attention than digital one due to the state‐of‐the‐art technology limitations of high‐resolution optical imaging in integrated devices. Optical metasurfaces, composed of ultrathin subwavelength meta‐atoms, are extensively considered for flat optical‐imaging nano‐components with high‐resolutions as competitive candidates for next‐generation miniaturized devices. Here, multiplex imaging metasurfaces composed of single nanorods are proposed under a detailed strategy to realize optical image steganography. The simulation and experimental results demonstrate that an optical steganographic metasurface can simultaneously transfer independent secret image information to two receivers with special keys, without raising suspicions for the general public under the cloak of a cover image. The proposed optical steganographic strategy by metasurfaces can arbitrarily distribute a continuous grayscale image together with a black‐and‐white image in separate channels, implying the distinguishing feature of high‐density information capacity for integration and miniaturization in optical meta‐devices.
Optical image steganography, a technique for hiding information, leads a primary role in securely transferring secret images to receivers on a public channel without raising suspicions. A brand‐new strategy using an ultrathin metasurface can obtain multiplexing image steganography that embeds two secret images into a cover image for independently transferring to different receivers as a kind of miniatured meta‐devices.
With a hypothesis that the social hierarchy of the grey wolves would be also followed in their searching positions, an improved grey wolf optimization (GWO) algorithm with variable weights (VW-GWO) ...is proposed. And to reduce the probability of being trapped in local optima, a new governing equation of the controlling parameter is also proposed. Simulation experiments are carried out, and comparisons are made. Results show that the proposed VW-GWO algorithm works better than the standard GWO, the ant lion optimization (ALO), the particle swarm optimization (PSO) algorithm, and the bat algorithm (BA). The novel VW-GWO algorithm is also verified in high-dimensional problems.
Halide methyltransferases (HMTs) provide an effective way to regenerate S‐adenosyl methionine (SAM) from S‐adenosyl homocysteine and reactive electrophiles, such as methyl iodide (MeI) and methyl ...toluene sulfonate (MeOTs). As compared with MeI, the cost‐effective unnatural substrate MeOTs can be accessed directly from cheap and abundant alcohols, but shows only limited reactivity in SAM production. In this study, we developed a dynamic cross‐correlation network analysis (DCCNA) strategy for quickly identifying hot spots influencing the catalytic efficiency of the enzyme, and applied it to the evolution of HMT from Paraburkholderia xenovorans. Finally, the optimal mutant, M4 (V55T/C125S/L127T/L129P), exhibited remarkable improvement, with a specific activity of 4.08 U/mg towards MeOTs, representing an 82‐fold increase as compared to the wild‐type (WT) enzyme. Notably, M4 also demonstrated a positive impact on the catalytic ability with other methyl donors. The structural mechanism behind the enhanced enzyme activity was uncovered by molecular dynamics simulations. Our work not only contributes a promising biocatalyst for the regeneration of SAM, but also offers a strategy for efficient enzyme engineering.
S‐Adenosylmethionine assumes a crucial role in biocatalytic alkylation. To improve the catalytic ability of BxHMT towards methyl toluene sulfonate, a strategy named dynamic cross‐correlation network analysis (DCCNA) was proposed for the identification of potential mutation sites, both distal and proximal. Experimental results proved the efficiency of the approach, which is expected to be a useful tool for other enzyme engineering studies.
Furancarboxylic acids are promising biobased building blocks in pharmaceutical and polymer industries. In this work, dual‐enzyme cascade systems composed of galactose oxidase (GOase) and alcohol ...dehydrogenases (ADHs) are constructed for controlled synthesis of 5‐formyl‐2‐furancarboxylic acid (FFCA) and 2,5‐furandicarboxylic acid (FDCA) from 5‐hydroxymethylfurfural (HMF), based on the catalytic promiscuity of ADHs. The byproduct H2O2, which is produced in GOase‐catalyzed oxidation of HMF to 2,5‐diformylfuran (DFF), is used for horseradish peroxidase (HRP)‐mediated regeneration of the oxidized nicotinamide cofactors for subsequent oxidation of DFF promoted by an ADH, thus implementing H2O2 internal recycling. The desired products FFCA and FDCA are obtained with yields of more than 95 %.
Internal affairs: A dual‐enzyme cascade system, composed of galactose oxidase and alcohol dehydrogenases (ADHs), is developed for controlled synthesis of furancarboxylic acids from 5‐hydroxymethylfurfural, based on the catalytic promiscuity of ADHs. The byproduct H2O2 is used for horseradish peroxidase‐mediated regeneration of the oxidized nicotinamide cofactors, thus implementing H2O2 internal recycling.
Notwithstanding the significant attention that network function virtualization architectures received over the last few years, little attention has been placed on cases where proactive caching is ...considered within a service chain. Caching algorithms have been developed independently from virtual network function (VNF) chaining schemes, and as we explain in detail in this paper such operation might lead to sub-optimal overall network and service performance. Since caching of popular content is envisioned to be one of the key adopted technologies in emerging 5G networks to increase network efficiency and overall end user perceived quality of service, we explicitly consider the interplay and subsequent optimization of caching-based VNF service chains. To this end, a mathematical programming framework is proposed tailored to VNF caching chains and, in addition, we detail a scale-free heuristic algorithm to provide competitive solutions for large network instances since the problem itself can be seen as a variant of the classical NP-hard uncapacitated facility location problem. A wide set of numerical investigations is presented for characterizing the attainable system performance of the proposed schemes.
We propose a novel approach to generating optical pulling forces on a gold nanowire, which are placed inside or above a hyperbolic metamaterial and subjected to plane wave illumination. Two ...mechanisms are found to induce the optical pulling force, including the concave isofrequency contour of the hyperbolic metamaterial and the excitation of directional surface plasmon polaritons. We systematically study the optical forces under various conditions, including the wavelength, the angle of incidence of light, and the nanowire radius. It is shown that the optical pulling force enabled by hyperbolic metamaterials is broadband and insensitive to the angle of incidence. The mechanisms and results reported here open a new avenue to manipulating nanoscale objects.
Prior to zygotic genome activation, early mammalian development relies on maternal-effect genes to orchestrate the oocyte-to-embryo transition. Recently, a subcortical maternal complex (SCMC) was ...identified to be essential for mouse preimplantation development. The SCMC integrates multiple proteins encoded by maternal-effect genes and appears to be functionally conserved across mammalian species. In addition, mutations in human SCMC genes are associated with certain human reproductive disorders. Here, we highlight recent advances in the biology of the SCMC and propose that this complex may be a representative example of maternal functional modules in mammalian oocyte-to-embryo transition. These findings may provide further insights into the molecular regulation of mammalian early embryogenesis, with possible implications for human early embryonic development and reproduction medicine.
Apart from the mitochondria, nucleoli, and various other individual maternal factors in the oocyte, the SCMC has been identified as an oocyte-to-embryo-specific protein complex, indispensable for the development of early mouse life.
The SCMC comprises Mater, Filia, Floped, Tle6, Zbed3, Nlrp2, and possibly Padi6 and other proteins, in mice. All known components of the SCMC are encoded by maternal-effect genes.
The SCMC orchestrates multiple developmental events during the mouse oocyte-to-embryo transition, including zygotic genome activation, F-actin dynamics, genome stability, organelle organization, and DNA methylation maintenance at imprinted loci.
The SCMC is functionally conserved across mammals, including humans. Certain clinical human reproductive disorders are associated with mutations in SCMC genes.
The SCMC acts as a representative example of maternal functional modules, providing an opportunity to better understand maternal control of early embryogenesis in mammals, especially humans.
Highlights ► Recent examples improving the processes performance of existing reactions were highlighted in this review. ► Some recent new synthetic routes for the synthesis of chiral chemicals were ...outlined in this review. ► Some recent important and interesting enzymes for the synthesis of chiral chemicals were focused on in this review.
Many new algorithms have been proposed to solve the mathematical equations formulated to describe the real-world problems. But there still does not exist one algorithm that could solve the problems ...all. And most of the proposed algorithms have defects in some aspects, they need to be improved in application. In order to find a more efficient optimization algorithm and inspired by the better performance of the Arithmetic Optimization algorithm (AOA) and Aquila Optimizer (AO), we proposed a hybridization algorithm of them and abbreviated AOAAO in this paper. Considering the better performance of the Harris Hawk optimization (HHO) algorithm, an energy parameter E was also introduced to balance the exploration and exploitation procedures of individuals in AOAAO swarms, and furthermore, piecewise linear map was introduced to decrease the randomness of the energy parameter. Pseudo code of the proposed AOAAO algorithm was presented, Simulation experiments were carried out on the benchmark functions and three classical engineering problems were also involved in optimization. Nine popular well demonstrated algorithms were included for comparison. Results confirmed the AOAAO would be more efficient in optimization with faster convergence rate, and higher convergence accuracy.
Because of the No Free Lunch (NFL) rule, we are still under the way developing new algorithms and improving the capabilities of the existed algorithms. Under consideration of the simple and steady ...convergence capability of the sine cosine algorithm (SCA) and the fast convergence rate of the Harris Hawk optimization (HHO) algorithms, we hereby propose a new hybridization algorithm of the SCA and HHO algorithm in this paper, called the CSCAHHO algorithm henceforth. The energy parameter is introduced to balance the exploration and exploitation procedure for individuals in the new swarm, and chaos is introduced to improve the randomness. Updating equations is redefined and combined of the equations in the SCA and HHO algorithms. Simulation experiments on 27 benchmark functions and CEC 2014 competitive functions, together with 3 engineering problems are carried out. Comparisons have been made with the original SCA, HHO, Archimedes optimization algorithm (AOA), Seagull optimization algorithm (SOA), Sooty Tern optimization algorithm (STOA), Arithmetic optimizer (AO) and Chimp optimization algorithm (ChOA). Simulation experiments on either unimodal or multimodal, benchmark or CEC2014 functions, or real engineering problems all verified the better performance of the proposed CSAHHO, such as faster convergence rate, low residual errors, and steadier capability. Matlab code of this algorithm is shared in Gitee with the following address: https://gitee.com/yuj-zhang/cscahho.
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