Using heterogeneous satellites for passive detection of moving aerial target

Passive detection of a moving aerial target is critical for intelligent surveillance. Its implementation can use signals transmitted from satellites. Nowadays, various types of satellites co-exist which can be used for passive detection. As a result, a satellite signal receiver may receive signals from multiple heterogeneous satellites, causing difficult in echo signal detection. In this paper, a passive moving aerial target detection method leveraging signals from multiple heterogeneous satellites is proposed. In the proposed method, a plurality of direct wave signals is separated in a reference channel first. Then, an adaptive filter with normalized least-mean-square (NLMS) is adopted to suppress direct-path interference (DPI) and multi-path interference (MPI) in a surveillance channel. Next, the maximum values of the cross ambiguity function (CAF) and the fourth order cyclic cumulants cross ambiguity function (FOCCCAF) correspond into each separated direct wave signal and echo signal will be utilized as the detection statistic of each distributed sensor. Finally, final detection probabilities are calculated by decision fusion based on results from distributed sensors. To evaluate the performance of the proposed method, extensive simulation studies are conducted. The corresponding simulation results show that the proposed fusion detection method can significantly improve the reliability of moving aerial target detection using multiple heterogeneous satellites. Moveover, we also show that the proposed detection method is able to significantly improve the detection performance by using multiple collaborative heterogeneous satellites

Palladium Supported on Carbon Nanotubes for Methane Catalytic Oxidation

A series of palladium/multi-walled carbon nanotube (Pd/MWCNT) catalysts were prepared for the total oxidation of methane. Their morphologies, thermal stabilities and redox properties were investigated using different analytical techniques. Their textural properties were also measured by the Brunauer-Emmett-Teller method. On this basis, the catalytic behaviors were tailored by pretreating with mixed acid solutions and changing the MWCNT diameters. The results show that higher MWCNT diameters improved the Pd dispersion and enhanced the catalytic properties of the Pd/MWCNT. A proper ratio of HNO3 to H2SO4 can provide moderately active sites such as oxygen-containing groups (OCG) and defects, on which the Pd precursor can be attached or anchored. Excessive H2SO4 will deteriorate the carbon framework and lower the frequency of OCG decorated on the outer surface of the MWCNT. As a result, the activity of the Pd/MWCNT catalysts for methane oxidation is suppressed

Morphology-dependent performance of Co3O4 via facile and controllable synthesis for methane combustion

Spinel type cobalt oxide (Co3O4) nanocrystals were controllably synthesized with different morphologies (cubical, hexagonal and flower-like) via a facile hydrothermal method. The properties of the nanostructured Co3O4 were characterized by XRD, SEM, TEM, HRTEM and XPS techniques. The performance of the catalysts in methane combustion was evaluated under lean methane atmosphere. Superior catalytic activities for methane combustion were observed over these oxides. The performances seemed to depend on their morphologies. The catalytic activities of flower-like Co3O4 and hexagonal plate-like Co3O4 were comparable to those of noble metal catalysts due to the preferred exposure of more active {111} crystal plane. In case of cubical Co3O4 the {001} plane is the dominantly exposed crystal plane. The results may provide significant insights for the development of nanostructured metal oxide catalysts for the catalytic combustion of methane. (C) 2016 Elsevier B.V. All rights reserved

Uncovering the hidden threat: The widespread presence of chromosome-borne accessory genetic elements and novel antibiotic resistance genetic environments in Aeromonas

ABSTRACTThe emergence of antibiotic-resistant Aeromonas strains in clinical settings has presented an escalating burden on human and public health. The dissemination of antibiotic resistance in Aeromonas is predominantly facilitated by chromosome-borne accessory genetic elements, although the existing literature on this subject remains limited. Hence, the primary objective of this study is to comprehensively investigate the genomic characteristics of chromosome-borne accessory genetic elements in Aeromonas. Moreover, the study aims to uncover novel genetic environments associated with antibiotic resistance on these elements. Aeromonas were screened from nonduplicated strains collected from two tertiary hospitals in China. Complete sequencing and population genetics analysis were performed. BLAST analysis was employed to identify related elements. All newly identified elements were subjected to detailed sequence annotation, dissection, and comparison. We identified and newly designated 19 chromosomal elements, including 18 integrative and mobilizable elements (IMEs) that could be classified into four categories: Tn6737-related, Tn6836-related, Tn6840-related, and Tn6844a-related IMEs. Each class exhibited a distinct pattern in the types of resistance genes carried by the IMEs. Several novel antibiotic resistance genetic environments were uncovered in these elements. Notably, we report the first identification of the blaOXA-10 gene and blaVEB-1 gene in clinical A. veronii genome, the first presence of a tetA(E)–tetR(E) resistance gene environment within the backbone region in IMEs, and a new mcr-3.15 resistance gene environment. The implications of these findings are substantial, as they provide new insights into the evolution, structure, and dissemination of chromosomal-borne accessory elements

Heterogeneous DNA hydrogel loaded with Apt02 modified tetrahedral framework nucleic acid accelerated critical-size bone defect repair

Segmental bone defects, stemming from trauma, infection, and tumors, pose formidable clinical challenges. Traditional bone repair materials, such as autologous and allogeneic bone grafts, grapple with limitations including source scarcity and immune rejection risks. The advent of nucleic acid nanotechnology, particularly the use of DNA hydrogels in tissue engineering, presents a promising solution, attributed to their biocompatibility, biodegradability, and programmability. However, these hydrogels, typically hindered by high gelation temperatures (∼46 °C) and high construction costs, limit cell encapsulation and broader application. Our research introduces a novel polymer-modified DNA hydrogel, developed using nucleic acid nanotechnology, which gels at a more biocompatible temperature of 37 °C and is cost-effective. This hydrogel then incorporates tetrahedral Framework Nucleic Acid (tFNA) to enhance osteogenic mineralization. Furthermore, considering the modifiability of tFNA, we modified its chains with Aptamer02 (Apt02), an aptamer known to foster angiogenesis. This dual approach significantly accelerates osteogenic differentiation in bone marrow stromal cells (BMSCs) and angiogenesis in human umbilical vein endothelial cells (HUVECs), with cell sequencing confirming their targeting efficacy, respectively. In vivo experiments in rats with critical-size cranial bone defects demonstrate their effectiveness in enhancing new bone formation. This innovation not only offers a viable solution for repairing segmental bone defects but also opens avenues for future advancements in bone organoids construction, marking a significant advancement in tissue engineering and regenerative medicine