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Botnet is one of main threats towards the Internet.Currently, botnets can expand to the whole world due to various types of network services, pervasive security vulnerabilities and massive deployment of networked devices, e.g., internet of things (IoT) devices.Future botnets will become more cross-platform and stealthy, which introduces severe security risks to cyberspace.Therefore, in-depth research on botnets can offer study targets to corresponding defensive studies, which is very meaningful for designing an architecture to secure the next-generation cyberspace.Hence, an HTTP-based scalable botnet framework was proposed to address the problems of compatibility, stealthiness and security.Specifically, the framework adopted a centralized controlling model.Moreover, it used the HTTP protocol as the designed botnet’s communication protocol and block encryption mechanisms based on symmetric cryptography to protect the botnet’s communication contents.Furthermore, a secure control mechanism for multi-platform botnets was designed.In particular, the proposed mechanism utilized source-level code integration and cross-compilation techniques to solve the compatibility challenge.It also introduced encrypted communication with dynamic secret keys to overcome the drawbacks of network traffic regularity and ease of analysis in traditional botnets.Moreover, it designed server migration and reconnection mechanisms to address the weakness of single-point-failure in centralized botnet models.Simulation results in three experimental scenarios with different levels of botnet controllability show that there is a linear relationship between the size of a botnet and the service overhead of the related C＆amp;C servers.In addition, under the condition of the same botnet scale, a higher level of controllability introduces a higher throughput and a greater system overhead.The above results demonstrate the effectiveness and the practical feasibility of the proposed method.

Three‐way catalysis represents a pivotal technology for converting automobile exhaust pollutants into non‐toxic gases. Substituting some noble metals with transition metals is considered a promising way to reduce catalyst costs. Herein, we have investigated the catalytic potential of different configurations of Pd−Cu catalysts prepared by impregnation (PdCu/MA), sol‐gel (PdCu‐MA), impregnation with physical mixing (Pd/Cu/MA) and sol‐gel with physical mixing (Pd/Cu‐MA) to modify the interaction of Pd/Cu and MgAl1.82Ce0.18O4 (MA) spinel in this comparative study. The different structures in these catalysts lead to different catalytic performances. PdCu/MA exhibits the best three‐way catalytic performance, which owe to the small‐sized PdCu particles with high Pd2+ content (45.3 %) and optimal interaction of Pd/Cu particles and MgAl1.82Ce0.18O4 support. Furthermore, comprehensive CO‐DRIFTS, H2‐TPR, and O2‐TPD analyses discover that the metal‐support interaction is beneficial to enhance the catalytic performance in three‐way catalysis. Overall, we demonstrated that the interaction between PdCu bimetals and support can regulate the electronic state of Pd, thereby enhancing the use and efficiency of noble metals. [ABSTRACT FROM AUTHOR]

The fault diagnosis of rotating machinery is vital in industry but traditionally depends on manual expertise, requiring substantial resources. To improve diagnostic accuracy, enable effective condition monitoring, and minimize the impact of faults on operations, advanced diagnostic techniques are essential. Hence, we propose an advanced fault diagnosis framework that leverages improved particle swarm optimization (IPSO), variational mode decomposition (VMD), and probabilistic neural networks (PNN) to accurately diagnose faults in rotating machinery using gear and rolling bearing vibration signals. Initially, the vibration signals are decomposed into intrinsic mode functions via VMD, enabling the capture of subtle but critical fault features. To address parameter selection challenges in VMD, we employed IPSO to optimize the VMD parameters, ensuring the optimal decomposition effect. Further, we refined the feature set by applying Laplace fraction optimization and feature dimensionality reduction, isolating sensitive features that serve as input to a PNN-based fault classification model. Experimental results demonstrated that this IPSO-VMD-PNN framework achieves high diagnostic accuracy for various fault types, establishing it as an effective tool for fault identification in rotating machinery. [ABSTRACT FROM AUTHOR]

The three-way catalysts (TWC) are required to have high thermal stability and excellent catalytic activity. The MgAl2O4 spinel is a thermal stable material, but its reactivity is unsatisfactory. In this work, CeO2 was used as a promoter to modify MgAl2O4 spinel, and the cerium modified MgAl2O4 spinel (MAC) was applied as the carrier to construct PdCu/MAC catalyst. The catalytic activity evaluation showed that modifying MgAl2O4 spinel with a handful of cerium (0.12 mol-Ce/mol-Mg) dramatically improved the three-way catalytic activity, especially for the elimination of NOx and C3H8. The XRD and XPS proved that these cerium cations incorporated into spinel lattices and occupied Al sites. For this reason, the cerium in PdCu/MAC-1 is mainly in +3 valence (Ce3+/Ce = 60.2%), which is accompanied by the formation of abundant oxygen vacancies (45.9%). These factors significantly promoted the dispersion of PdCu nanoparticles, and thus strengthened metal-support interaction, consequently the enhanced catalytic performance. However, adding excessive cerium (0.24 mol-Ce/mol-Mg) resulted in negative effect. This might be related to the appearance of isolated CeO2 crystal originating from the separate nucleation of excessive cerium cations. This work provides some guidance for developing TWC with both high thermal stability and activity. [ABSTRACT FROM AUTHOR]

Drug-induced cardiotoxicity is a significant contributor to drug recalls, primarily attributed to limitations in existing drug screening platforms. Traditional heart-on-a-chip platforms often employ metallic electrodes to record cardiomyocyte electrical signals. However, this approach hinders direct cardiomyocyte morphology observation and typically yields limited functionality. Consequently, this limitation may lead to an incomplete understanding of cardiomyocyte characteristics. To address these challenges, we introduce a multifunctional cardiac microphysiological system featuring transparent indium tin oxide electrodes. This innovative design aims to overcome the limitations of conventional heart-on-a-chip systems where metal electrodes interfere with the observation of cells and increase the difficulty of subsequent image processing of cell images. In addition to facilitating optical measurement combined with image processing capabilities, this system integrates a range of electrodes with diverse functionalities. These electrodes can realize cellular electrical stimulation, field potential monitoring, and impedance change tracking, enabling a comprehensive investigation of various cardiomyocyte traits. To demonstrate its versatility, we investigate the effects of four cardiac drugs with distinct pharmacological profiles on cardiomyocytes using this system. This platform provides a means for quantitatively and predictively assessing cardiac toxicity, which could be applied to conduct a comprehensive evaluation during the drug discovery process. [ABSTRACT FROM AUTHOR]

In vitro organoid models, typically defined as 3D multicellular aggregates, have been extensively used as a promising tool in drug screening, disease progression research, and precision medicine. Combined with advanced microfluidics technique, organoid-on-a-chip can flexibly replicate in vivo organs within the biomimetic physiological microenvironment by accurately regulating different parameters, such as fluid conditions and concentration gradients of biochemical factors. Since engineered organ reconstruction has opened a new paradigm in biomedicine, innovative approaches are increasingly required in micro-nano fabrication, tissue construction, and development of pharmaceutical products. In this Perspective review, the advantages and characteristics of organoid-on-a-chip are first introduced. Challenges in current organoid culture, extracellular matrix building, and device manufacturing techniques are subsequently demonstrated, followed by potential alternative approaches, respectively. The future directions and emerging application scenarios of organoid-on-a-chip are finally prospected to further satisfy the clinical demands. [ABSTRACT FROM AUTHOR]

In this paper, we prepared a series of Ce1-xTixO2 (x = 0–0.20) nanorods by hydrothermal method, which were used to construct the PdCu/Ce1−xTixO2 catalysts. The Ce1−xTixO2 and PdCu/Ce1−xTixO2 samples were characterized by transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), N2 adsorption–desorption, X-ray diffraction (XRD), inductively coupled plasma optical emission spectrometer (ICP-OES), etc. Catalytic activity, stability, and repeatability of the catalysts for methanol oxidation were investigated. The results show that doping a proper amount of titanium could strengthen the interaction between Ce1−xTixO2 support and PdCu nanoalloy, thus increasing the oxygen vacancy concentration and promoting Pd species with a higher oxidation state. These modified properties are beneficial for the deep oxidation of methanol. The light-off temperature (T50) and full-conversion temperature (T90) of methanol over the PdCu/CeO2 catalyst are 108 °C and 159 °C, respectively. The greatest activity improvement is found for PdCu/Ce0.9Ti0.1O2, which shows the lowest T50 of 88 °C and T90 of 138 °C. Furthermore, neither PdCu/CeO2 nor the modified PdCu/CeO2 catalyst produces by-products and exhibit excellent stability and repeatability throughout the whole test period. This study provides a reference for in-depth understanding and designing of efficient and stable CeO2-based oxidation catalysts. [ABSTRACT FROM AUTHOR]