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Currently, monocular simultaneous location and mapping (SLAM) systems cannot extract depth information from monocular cameras directly and require initialization to solve the problem of scale uncertainty. It is extremely difficult to reconstruct maps using such systems, and it is difficult to cope with scenarios that require navigation and obstacle avoidance. In order to solve the above problems, in this article, a simple monocular depth estimation network framework is proposed. Transfer learning from a pre-trained ResNet is utilized for the encoding part of the framework and a convolutional neural network (CNN) is used for the decoding part. Only a few training parameters and iterations are required to obtain fairly accurate depth information. At the same time, a similarity-based filter is used to denoise the surfels and improve the red green blue-depth (RGB-D) SLAM system, which not only reduces the impact of the depth estimation error on the surfels but also ensures the quality of the dense mapping. From the results of comparative experiments, it can be seen that the proposed monocular depth estimation network framework is better than current popular methods, and the associated SLAM system can achieve pose estimation and dense mapping tasks. As a monocular camera-based SLAM system, the proposed method is a promising and practical approach.

This article proposes a robust dynamic feature segmentation simultaneous localization and mapping (SLAM) 3-D reconstruction algorithm based on the dynamic segmentation framework of DynaSLAM in order to realize the SLAM system mapping in the dynamic environment of intelligent robots. The algorithm employs the method of feature point reextraction to solve the problem of an insufficient number of original feature points. In the preprocessing stage, the optimized epipolar geometry model is designed in this article, and the image is segmented jointly with Mask R-CNN. At the point cloud postprocessing stage, a kernel principal component analysis (PCA) is used to reduce noise, and then, this article designs a dynamic filtering method based on octree for further processing. This processing effectively eliminates additional dynamic outliers. The results of experiments on TUM and Bonn datasets show that this algorithm achieves more than 10% better attitude estimation accuracy than the DynaSLAM algorithm in a highly dynamic environment and has advantages over the state-of-the-art (SOTA) algorithms.

ABSTRACTStreptococcus suisserotype 2 (SS2), an emerging zoonotic pathogen, causes swine diseases and human cases of streptococcal toxic shock syndrome. RNA-binding proteins (RBPs) can modulate gene expression through post-transcriptional regulation. In this study, we identified an RBP harbouring an S1 domain, named RbpA, which facilitated SS2 adhesion to host epithelial cells and contributed to bacterial pathogenicity. Comparative proteomic analysis identified 145 proteins that were expressed differentially between ΔrbpAstrain and wild-type strain, including several virulence-associated factors, such as the extracellular protein factor (EF), SrtF pilus, IgA1 protease, SBP2 pilus, and peptidoglycan-binding LysM’ proteins. The mechanisms underlying the regulatory effects of RbpA on their encoding genes were explored, and it was found that RbpA regulates gene expression through diverse mechanisms, including post-transcriptional regulation, and thus acts as a global regulator. These results partly reveal the pathogenic mechanism mediated by RbpA, improving our understanding of the regulatory systems of S. suisand providing new insights into bacterial pathogenicity.

Traditional internal combustion engines (ICEs) have garnered considerable attention due to their high emissions and low efficiency issues. In this study, a novel ICE–fuel cell hybrid power system based on a single‐methanol fuel is proposed to address these concerns. The system utilizes methanol as fuel, directly supplying it to the methanol engine, and generates hydrogen for the fuel cell through methanol reforming technology. The structural design of the system fully exploits engine exhaust, first using waste heat for methanol reforming to produce hydrogen and then utilizing exhaust inertial potential energy to drive a dual turbocharging structure for air compression entering the fuel cell, thereby achieving self‐thermal balance. Thermodynamic analysis and cost evaluation indicate that the thermal efficiency of this system is improved by 8.34% compared to traditional diesel engine setups. Compared to engine‐fuel cell hybrid systems that do not utilize waste heat, the thermal efficiency is increased by 5.81%. In terms of economics, the cost of the methanol engine system is ≈.1466$ kW h−1$\left(\text{kW h}\right)^{- 1}$, which is 44.05% lower than the 0.262 $kW h−1$\left(\text{ kW h}\right)^{- 1}$fuel cost of traditional diesel engine systems. This study presents an innovative solution that significantly enhances thermal efficiency and offers economic advantages, providing a viable approach to address the low efficiency and high emissions issues of traditional ICEs. This study introduces a novel internal combustion engine–fuel cell hybrid power system based on single‐methanol fuel. The system design utilizes engine exhaust energy for methanol reforming to produce hydrogen and drive a dual turbocharger setup. Compared to conventional diesel engines, it achieves an 8.34% increase in thermal efficiency and reduces fuel costs by 44.05%.

Driven by increasingly stringent safety regulations and enhanced fire hazards awareness, rationally designing a highly flame-retardant and eco-friendly polymer composites has become critically significant, but remains challenging. Herein, to endow epoxy resin (EP) composites with exceptional fire safety while maintaining its desirable performances, a novel bio-nano flame retardant GPP@HNTs was successfully prepared via the electrostatic-driven hybridization of two natural-available green materials, halloysite nanotubes (HNTs) and phytic acid (PA). It was found that the GPP@HNTs can uniformly disperse in EP matrix due to its strong interfacial interaction with EP. In compassion with EP, the flame retardancy of GPP@HNTs/EP composites was effectively enhanced, reaching UL-94 V-0 rating and exhibiting a 42.55 % increase of LOI value, 32.76 % decrease in peak heat release rate (PHRR), 25.92 % reduction in total heat release (THR). Furthermore, the GPP@HNTs/EP composites also present excellent thermal stability and mechanical properties. Such a facile yet efficient hybridization design of bio-nano flame retardant paves the way for wide practical applications of the flame-retardant and mechanically robust EP composites in various industrial fields.

ABSTRACTThe Streptococcus suisserotype 2 (SS2) is a significant zoonotic pathogen that is responsible for various swine diseases, even causing cytokine storms of Streptococcal toxic shock-like syndromes amongst human. Cell wall anchoring proteins with a C-terminal LPxTG are considered to play vital roles during SS2 infection; however, their exporting mechanism across cytoplasmic membranes has remained vague. This study found that YSIRK-G/S was involved in the exportation of LPxTG-anchoring virulence factors MRP and SspA in virulent SS2 strain ZY05719. The whole-genome analysis indicated that diverse LPxTG proteins fused with an N-terminal YSIRK-G/S motif are encoded in strain ZY05719. Two novel LPxTG proteins SspB and YzpA were verified to be exported via a putative transport system that was dependent on the YSIRK-G/S directed translocation, and portrayed vital functions during the infection of SS2 strain ZY05719. Instead of exhibiting an inactivation of C5a peptidase in SspB, another LPxTG protein with an N-terminal YSIRK-G/S motif from Streptococcus agalactiaewas depicted to cleave the C5a component of the host complement. The consequent domain-architecture retrieval determined more than 10,000 SspB/YzpA like proteins that are extensively distributed in the Gram-positive bacteria, and most of them harbor diverse glycosyl hydrolase or peptidase domains within their middle regions, thus presenting their capability to interact with host cells. The said findings provide compelling evidence that LPxTG proteins with an N-terminal YSIRK-G/S motif are polymorphic effectors secreted by Gram-positive bacteria, which can be further proposed to define as cell wall anchoring effectors in a new subset.

Toxin-antitoxin (TA) systems, which are prevalent in bacteria and archaea, play diverse roles in bacterial physiology and have been proposed to be significant in stress adaptation. Despite the extensive characterization of numerous TA systems in various bacteria, the investigation of these systems within Streptococcus suis(S. suis) is still limited. Here, we systematically analyzed the type II TA systems of 95 S. suisgenomes available in the GenBank database using TAfinder. A total of 612 putative type II TA systems were retrieved and classified into 10 categories by phylogenetic analysis. Notably, an elevated occurrence of these TA systems was observed among the important prevalent serotypes 2, 4, 5, 9, 14, Chz, NCL1, and NCL3 strains. The following study identified the activities of TA systems using two strategies and confirmed the regulatory effect of HigBA on the type VII secretion system in S. suisby measuring β-galactosidase activity and transcriptional changes. Moreover, we unveiled a hitherto uncharacterized, highly prevalent novel TA system, with the composition of antitoxin-toxin-antitoxin (SS-ATA), which regulates the downstream two-component signaling system. Altogether, this study systematically analyzed the type II TA systems within S. suis, highlighting the widespread distribution of HigBA and SS-ATA as important regulatory elements in S. suis.

Aim:To develop a markerless gene deletion strategy in Streptococcus suisto solve the problem that several serotypes against electrotransformation of foreign DNA. Materials & methods:Bioinformatics retrieval was performed to identified ComRS systems functioning for natural transformation. A sacB-spccassette with the upper and lower homologous fragments was amplification by fusion-PCR for spectinomycin-positive and sucrose-negative selection during gene deletion. Results & conclusion:Three phylogenetic clusters of ComR were identified to function for natural transformation by specific recognition to competence pheromone in S. suis.Thus, they were employed to establish gene deletion method. Its efficiency for genetic replacement was dependent on the length of homologs fragment and the concentration of donor DNA. This rapid gene-editing technique may greatly facilitate molecular studies on S. suis.

Recent observational studies showed that breast-conserving surgery (BCS) resulted in superior survival compared to mastectomy in breast cancer patients. This study compared the clinical outcomes of BCS and mastectomy using propensity score (PS) matching analysis, which had advantages over conventional methods in reducing bias. Nonmetastatic breast cancer patients who underwent BCS and mastectomy were matched 1:1 based on their PS. We used the Kaplan-Meier method and Cox-regression model to estimate the treatment effects. A total of 2,866 patients with a median follow-up time of 67 months were included in the original study population. Although the mastectomy cohort (N=1,219) had more advanced disease compared to the BCS cohort (N=1,647), LRFS was similar between the two groups (93.8% vs. 92.4%, P>0.05). BCS (vs. mastectomy) was associated with improved DFS (73.8% vs. 58.7%, P<0.01) and CSS (91% vs. 78.2%, P<0.01) in the original population. In the PS-matched population (N=1,668), clinicopathological features were equally distributed between the two cohorts. BCS (vs. mastectomy) was not associated with improved DFS (70.7% vs. 66.9%, P>0.05) or CSS (87.5% vs. 84.9%, P>0.05). We found that PS methods reduce bias when estimating treatment effects using observational data. BCS and mastectomy show equivalent outcomes in nonmetastatic breast cancer patients.

ABSTRACTThe type VI secretion system (T6SS) is a widespread molecular weapon deployed by many bacterial species to target eukaryotic host cells or rival bacteria. Using a dynamic injection mechanism, diverse effectors can be delivered by T6SS directly into recipient cells. Here, we report a new family of T6SS effectors encoded by extended Hcps carrying diverse toxin domains. Bioinformatic analyses revealed that these Hcps with C-terminal extension toxins, designated as Hcp-ET, exist widely in the Enterobacteriaceae. To verify our findings, Hcp-ET1 was tested for its antibacterial effect, and showed effective inhibition of target cell growth via the predicted HNH-DNase activity by T6SS-dependent delivery. Further studies showed that Hcp-ET2 mediated interbacterial antagonism via a Tle1 phospholipase (encoded by DUF2235 domain) activity. Notably, comprehensive analyses of protein homology and genomic neighborhoods revealed that Hcp-ET3–4 is fused with 2 toxin domains (Pyocin S3 and Colicin-DNase) C-terminally, and its encoding gene is followed 3 duplications of the cognate immunity genes. However, some bacteria encode a separated hcp-et3and an orphan et4(et4O1) genes caused by a termination-codon mutation in the fusion region between Pyocin S3 and Colicin-DNase encoding fragments. Our results demonstrated that both of these toxins had antibacterial effects. Further, all duplications of the cognate immunity protein contributed to neutralize the DNase toxicity of Pyocin S3 and Colicin, which has not been reported previously. In conclusion, we propose that Hcp-ET proteins are polymorphic T6SS effectors, and thus present a novel encoding pattern of T6SS effectors.

ABSTRACTType VI secretion systems (T6SSs) are involved in the pathogenicity of several Gram-negative bacteria. The VgrG protein, a core component and effector of T6SS, has been demonstrated to perform diverse functions. The N-terminal domain of VgrG protein is a homologue of tail fiber protein gp27 of phage T4, which performs a receptor binding function and determines the host specificity. Based on sequence analysis, we found that two putative T6SS loci exist in the genome of the avian pathogenic Escherichia coli(APEC) strain TW-XM. To assess the contribution of these two T6SSs to TW-XM pathogenesis, the crucial clpVclusters of these two T6SS loci and their vgrGgenes were deleted to generate a series of mutants. Consequently, T6SS1-associated mutants presented diminished adherence to and invasion of several host cell lines cultured in vitro, decreased pathogenicity in duck and mouse infection models in vivo, and decreased biofilm formation and bacterial competitive advantage. In contrast, T6SS2-associated mutants presented a significant decrease only in the adherence to and invasion of mouse brain microvascular endothelial cell (BMEC) line bEnd.3 and brain tissue of the duck infection model. These results suggested that T6SS1 was involved in the proliferation of APEC in systemic infection, whereas VgrG-T6SS2 was responsible only for cerebral infection. Further study demonstrated that VgrG-T6SS2 was able to bind to the surface of bEnd.3 cells, whereas it did not bind to DF-1 (chicken embryo fibroblast) cells, which further proved the interaction of VgrG-T6SS2 with the surface of BMECs.

ABSTRACTAutotransporter (AT) proteins constitute a large family of extracellular proteins that contribute to bacterial virulence. A novel AT adhesin gene, aatB, was identified in avian pathogenic Escherichia coli(APEC) DE205B via genomic analyses. The open reading frame of aatBwas 1,017 bp, encoding a putative 36.3-kDa protein which contained structural motifs characteristic for AT proteins: a signal peptide, a passenger domain, and a translocator domain. The predicted three-dimensional structure of AatB consisted of two distinct domains, the C-terminal ß-barrel translocator domain and an N-terminal passenger domain. The prevalence analyses of aatBin APEC indicated that aatBwas detected in 26.4% (72/273) of APEC strains and was strongly associated with phylogenetic groups D and B2. Quantitative real-time reverse transcription-PCR analyses revealed that AatB expression was increased during infection in vitroand in vivo. Moreover, AatB could elicit antibodies in infected ducks, suggesting that AatB is involved in APEC pathogenicity. Thus, APEC DE205B strains with a mutated aatBgene and mutated strains complemented with the aatBgene were constructed. Inactivation of aatBresulted in a reduced capacity to adhere to DF-1 cells, defective virulence capacity in vivo, and decreased colonization capacity in lung during systemic infection compared with the capacities of the wild-type strain. Furthermore, these capacities were restored in the complementation strains. These results indicated that AatB makes a significant contribution to APEC virulence through bacterial adherence to host tissues in vivoand in vitro. In addition, biofilm formation assays with strain AAEC189 expressing AatB indicated that AatB mediates biofilm formation.

Streptococcus agalactiae(group B streptococcus [GBS]) has received continuous attention for its involvement in invasive infections and its broad host range. Transcriptional regulators have an important impact on bacterial adaptation to various environments. Research on transcriptional regulators will shed new light on GBS pathogenesis. In this study, we identified a novel XRE-family transcriptional regulator encoded on the GBS genome, designated XtgS. Our data demonstrate that XtgS inactivation significantly increases bacterial survival in host blood and animal challenge test, suggesting that it is a negative regulator of GBS pathogenicity.

Streptococcus suisis one of the most important pathogens affecting the swine industry and is also an emerging zoonotic agent for humans. Two-component signaling systems (TCSs) play important roles in the adaptation of pathogenic bacteria to host environments. In this study, we identified a novel TCS, named TCS09HKRR, which facilitated Streptococcus suisserotype 2 (SS2) resistance to clearance by the host immune system and contributed to bacterial pathogenicity.

ABSTRACTStreptococcus suishas received increasing attention for its involvement in severe human infections worldwide as well as in multidrug resistance. Two-component signaling systems (TCSSs) play important roles in bacterial adaptation to various environmental stimuli. In this study, we identified a novel TCSS located in S. suisserotype 2 (SS2), designated VraSRSS, which is involved in bacterial pathogenicity and susceptibility to antimicrobials. Our data demonstrated that the yvqFSSgene, located upstream of vraSRSS, shared the same promoter with the TCSS genes, which was directly regulated by VraSRSS, as shown in electrophoretic mobility shift assays. Notably, YvqFSSand VraSRSSconstitute a novel multidrug resistance module of SS2 that participates in resistance to certain groups of antimicrobials. Further analyses showed that VraSRSSinactivation significantly attenuated bacterial virulence in animal models, which, coupled with the significant activation of VraSRSSexpression observed in host blood, strongly suggested that VraSRSSis an important regulator of SS2 pathogenicity. Indeed, RNA-sequencing analyses identified 106 genes that were differentially expressed between the wild-type and ΔvraSRSSstrains, including genes involved in capsular polysaccharide (CPS) biosynthesis. Subsequent studies confirmed that VraSRSSindirectly regulated the transcription of CPS gene clusters and, thus, controlled the CPS thickness shown by transmission electron microscopy. Decreased CPS biosynthesis caused by vraSRSSdeletion subsequently increased bacterial adhesion to epithelial cells and attenuated antiphagocytosis against macrophages, which partially clarified the pathogenic mechanism mediated by VraSRSS. Taken together, our data suggest that the novel TCSS, VraSRSS, plays critical roles for multidrug resistance and full virulence in SS2.