Search Results (27)

This study investigated the optimal strategies for improving sugar biosynthesis in mango fruits. Randomized block design was used for experimental treatments. The mango cultivar “Renong-1” was sprayed with five green plant growth regulators, including solutions of SBP (sucrose-based polymers, a new highly efficient and eco-friendly plant growth regulator), SPM (sucrose + potassium dihydrogen phosphate + microelement fertilizer), TPM (taurine + potassium dihydrogen phosphate + microelement fertilize), PFA (potassium fulvic acid), and SOP (seaweed oligosaccharide peptide) at different fruit development stages. Indicators, such as soluble solid content, soluble sugar and starch contents, and activities of 11 enzymes associated with sugar metabolism in physiologically mature and in full ripening fruits were evaluated. The results showed that SBP solution diluted 100-fold exerted the strongest effect on the soluble sugar content and sweetness value of “Renong-1” mango fruits. Based on the linear regression analysis, a significant negative correlation was observed between the activity of acid invertase and the perceived sweetness of physiologically mature fruits, while the activities of other enzymes were significantly negatively correlated with the perceived sweetness of full ripening fruits. According to multiple regression (by lars function in R) and other comprehensive analysis, A1B3 (spraying SBP solution one time in the young fruit stage) was selected as the optimal treatment combination for enhancing “Renong-1” mango perceived sweetness, followed by A1B2 (spraying SBP solution for the first time in the young fruit stage and the second time at medium maturity) as the alternative treatment combination. Full article

Positioning based on Low Earth Orbit (LEO) satellite Signals of Opportunity (SOP) often relies on Doppler observations. Therefore, the accuracy of Doppler frequency measurements significantly impacts the positioning performance. Traditional frequency estimation methods for ORBCOMM satellite signals are typically implemented in the frequency domain and neglect the impact of the “frequency chirp” effect on measurement accuracy, which leads to low computational efficiency, poor noise resistance, and limited estimation accuracy. To address this issue, a high-precision frequency estimation method combining a “coarse and fine” process is proposed. In the coarse estimation process, ephemeris prior information is combined with matched filtering to effectively separate the Doppler rate, thereby mitigating the spectral broadening caused by the Doppler rate. In the fine estimation process, ORBCOMM signal characteristics are fully exploited. Single-sideband filtering is applied to improve noise resistance, followed by precise frequency discrimination of the delayed signal. Experimental results demonstrate that the proposed method outperforms the state-of-the-art “FFT + MLE” approach, achieving a frequency measurement accuracy on the order of 0.01 Hz while requiring fewer computational resources. Furthermore, this method improves estimation performance by approximately 12 dB without compromising frequency measurement accuracy. Full article

As aviation technology advances, numerous new aircraft enter the market. These not only offer airlines technological and fuel efficiency advantages but also present the challenge of how to conduct pilots’ aircraft-type transition training efficiently and economically. To address this issue, this study designed a methodology to quantitatively assess the similarity in panel display control design and standard operating procedures (SOPs) between aircraft types. Then, by combining the results of a questionnaire survey on A320, A330, B737, and B777 transition training and training cost data, it was verified quantitatively that inter-aircraft similarity has a positive impact on reducing the difficulty and cost of transition training. Taking the similarity in aircraft types as a feature, the KNN algorithm was used to successfully construct a difficulty prediction model for the training program of aircraft-type transition training. To overcome the limitation of insufficient training cost data volume, this study adopts the transfer learning method to construct a prediction model of the transition training cost, and the final significant prediction accuracy proves the effectiveness of the method. The research in this paper not only provides strong data support for the resource planning and cost management of airlines’ aircraft-type transition training but also provides new research perspectives and methodological guidance for the field of aviation training. Full article

Edema disease (ED) is a severe and lethal infectious ailment in swine, stemming from Shiga-toxin-producing Escherichia coli (STEC). An efficient, user-friendly, and safe vaccine against ED is urgently required to improve animal welfare and decrease antibiotic consumption. Recombinant attenuated Salmonella vaccines (RASV) administered orally induce both humoral and mucosal immune responses to the immunizing antigen. Their potential for inducing protective immunity against ED is significant through the delivery of STEC antigens. rSC0016 represents an enhanced recombinant attenuated vaccine vector designed for Salmonella enterica serotype Choleraesuis. It combines sopB mutations with a regulated delay system to strike a well-balanced equilibrium between host safety and immunogenicity. We generated recombinant vaccine strains, namely rSC0016 (pS-FedF) and rSC0016 (pS-rStx2eA), and assessed their safety and immunogenicity in vivo. The findings demonstrated that the mouse models immunized with rSC0016 (pS-FedF) and rSC0016 (pS-rStx2eA) generated substantial IgG antibody responses to FedF and rStx2eA, while also provoking robust mucosal and cellular immune responses against both FedF and rStx2eA. The protective impact of rSC0016 (pS-FedF) against Shiga-toxin-producing Escherichia coli surpassed that of rSC0016 (pS-rStx2eA), with percentages of 83.3%. These findings underscore that FedF has greater suitability for vaccine delivery via recombinant attenuated Salmonella vaccines (RASVs). Overall, this study provides a promising candidate vaccine for infection with STEC. Full article

Our study aimed to explore the effects of postbiotics on protecting against Salmonella infection in mice and clarify the underlying mechanisms. Eighty 5-week-old C57BL/6 mice were gavaged daily with Lactiplantibacillus plantarum (LP)-derived postbiotics (heat-killed bacteria, LPB_inactive; culture supernatant, LPC) or the active bacteria (LPB_active), and gavaged with Salmonella enterica Typhimurium (ST). The Turbidimetry test and agar diffusion assay indicated that LPC directly inhibited Salmonella growth. Real-time PCR and biofilm inhibition assay showed that LPC had a strong ability in suppressing Salmonella pathogenicity by reducing virulence genes (SopE, SopB, InvA, InvF, SipB, HilA, SipA and SopD2), pili genes (FilF, SefA, LpfA, FimF), flagellum genes (FlhD, FliC, FliD) and biofilm formation. LP postbiotics were more effective than LP on attenuating ST-induced intestinal damage in mice, as indicated by increasing villus/crypt ratio and increasing the expression levels of tight junction proteins (Occludin and Claudin-1). Elisa assay showed that LP postbiotics significantly reduced ST-induced inflammation by regulating the levels of inflammatory cytokines (the increased IL-4 and IL-10 and the decreased TNF-α) in serum and ileum (p < 0.05). Furthermore, LP postbiotics inhibited the activation of NOD-like receptor thermal protein domain-associated protein 3 (NLRP3) inflammasome by decreasing the protein expression of NLRP3 and Caspase-1, and the gene expression of Caspase-1, IL-1β and IL-18. Meanwhile, both LPC and LPB observably activated autophagy under ST infection, as indicated by the up-regulated expression of LC3 and Beclin1 and the downregulated p62 level (p < 0.05). Finally, we found that LP postbiotics could trigger an AMP-activated protein kinase (AMPK) signaling pathway to induce autophagy. In summary, Lactiplantibacillus plantarum-derived postbiotics alleviated Salmonella infection via modulating bacterial pathogenicity, autophagy and NLRP3 inflammasome in mice. Our results confirmed the effectiveness of postbiotics agents in the control of Salmonella infection. Full article

The aim of this study was to explore the association between antimicrobial resistance, ESBL genes, and virulence genes of Salmonella isolates. From 2019 to 2021, a total of 117 Salmonella isolates were obtained from symptomatic chickens in Sichuan Province, China. The strains were tested for antimicrobial resistance and the presence of ESBL according to the Clinical and Laboratory Standards Institute (CLSI) instructions. The presence of ESBL genes and genes for virulence was determined using Polymerase Chain Reaction (PCR). In addition, Multilocus Sequence Typing (MLST) was applied to confirm the molecular genotyping. Moreover, the mechanism of ESBL and virulence gene transfer and the relationships between the resistance phenotype, ESBL genes, and virulence genes were explored. The isolates exhibited different frequencies of resistance to antibiotics (resistance rates ranged from 21.37% to 97.44%), whereas 68.38% and 41.03% of isolates were multi-drug resistance (MDR) and ESBL-producers, respectively. In the PCR analysis, bla_CTX-M was the most prevalent ESBL genotype (73.42%, 58/79), and bla_CTX-M-55 showed the most significant effect on the resistance to cephalosporins as tested by logistic regression analysis. Isolates showed a high carriage rate of invA, avrA, sopB, sopE, ssaQ, spvR, spvB, spvC, stn, and bcfC (ranged from 51.28% to 100%). MLST analysis revealed that the 117 isolates were divided into 11 types, mainly ST92, ST11, and ST3717. Of 48 ESBL-producers, 21 transconjugants were successfully obtained by conjugation. Furthermore, ESBL and spv virulence genes were obtained simultaneously in 15 transconjugants. These results highlighted that Salmonella isolates were common carriers of ESBLs and multiple virulence genes. Horizontal transfer played a key role in disseminating antimicrobial resistance and pathogenesis. Therefore, it is necessary to continuously monitor the use of antimicrobials and the prevalence of AMR and virulence in Salmonella from food animals and to improve the antibiotic stewardship for salmonellosis. Full article

Salmonella enterica is a pathogen capable of colonizing various environments, including the intestinal tract of different animals such as mammals, birds, and reptiles, which can act as carriers. S. enterica infection induces different clinical diseases, gastroenteritis being the most common, which in some cases, can evolve to septicemia and meningitis. Reptiles and amphibians have been reported as a reservoir of Salmonella, and transmission of the pathogen to humans has been documented. This study aimed to determine the presence of virulence genes and characterize the genotypic antibiotic resistance profile in Salmonella strains isolated from Caiman crocodilus fuscus obtained in situ (natural habitat) in Prado, Tolima, Colombia in a previous study and stored in a strain bank in our laboratory. Fifteen Salmonella strains were evaluated through endpoint PCR to determine the presence of resistance genes and virulence genes. The genes bla_TEM, strB, and sul1 were detected in all the strains that confer resistance to ampicillin, streptomycin, and sulfamethoxazole, as well as the virulence genes invA, pefA, prgH, spaN, tolC, sipB, sitC, pagC, msgA, spiA, sopB, sifA, lpfA, csgA, hilA, orgA, iroN, avrA, and sivH, indicating the possible role of babilla (Caiman crocodilus fuscus) as a carrier of multidrug-resistant bacteria. Full article

One of the most common diseases affecting people and leading to high morbidity is kidney injury. The alleviation of inflammation and apoptosis is considered a potential therapeutic approach for kidney injury. Sophocarpine (SOP), a tetracyclic quinolizidine alkaloid, exhibits various beneficial biological properties. To investigate the effects of SOP on isoproterenol (ISO)-induced kidney injury, we randomly divided mice into four groups: Control, ISO, ISO+SOP (20 mg/kg) and ISO+SOP (40 mg/kg). SOP was administered intraperitoneally to the mice over two weeks, accompanied by intraperitoneal stimulation of ISO (10 mg/kg) for another four weeks. After the mice were sacrificed, several methods such as ELISA, staining (H&E, TUNEL, DHE and Masson) and Western blotting were applied to detect the corresponding indicators. The kidney injury serum biomarkers SCr and BUN increased after the ISO challenge, while this effect was reversed by treatment with SOP. Pathological changes induced by ISO were also reversed by treatment with SOP in the staining. The inflammatory cytokines IL-β, IL-6, TNF-α, MCP-1 and NLRP3 increased after the challenge with ISO, while they were decreased by treatment with SOP. The apoptotic proteins cleaved-caspase-3 and Bax increased, while Bcl-2 decreased, after the challenge with ISO, and these effects were reversed by treatment with SOP. The antioxidant proteins SOD-1 and SOD-2 decreased after being stimulated by ISO, while they increased after the treatment with SOP. The fibrotic proteins collagen I, collagen III, α-SMA, fibronectin, MMP-2 and MMP-9 increased after the challenge with ISO, while they decreased after the treatment with SOP. We further discovered that the TLR-4/NF-κB and TGF-β1/Smad3 signaling pathways were suppressed, while the Nrf2/HO-1 signaling pathway was activated. In summary, SOP could alleviate ISO-induced kidney injury by inhibiting inflammation, apoptosis, oxidative stress and fibrosis. The molecular mechanisms were suppression of the TLR-4/NF-κB and TGF-β1/Smad3 signaling pathways and activation of the Nrf2/HO-1 signaling pathway, indicating that SOP might serve as a novel therapeutic strategy for kidney injury. Full article

Unmanned aerial vehicle (UAV)-based relaying has been considered to offer an excellent performance due to its flexible mobility, on-demand deployment, and cost effectiveness compared to conventional ground-relaying methods. This paper studies the secrecy performance of a dual-hop UAV-assisted relay network, where the base station communicates with the ground user via a low altitude UAV in the presence of randomly distributed eavesdroppers. A stochastic geometric approach is employed to model the spatial locations of the ground user and the eavesdroppers which follows a Homogeneous Poisson Point Process (HPPP). Based on this theory, cumulative distribution functions (CDF) of the ground user and the eavesdroppers are obtained. Considering the decode-and-forward (DF) relay protocol, the CDF equivalent end-to-end instantaneous signal-to-noise ratio (SNR) of the network is derived. To characterize the network secrecy performance, the exact analytical expressions for the network security outage probability (SOP), the strictly positive secrecy capacity (SPSC), and the average secrecy capacity (ASC) are derived. Moreover, a Monte-Carlo simulation is provided to show the accuracy of the derived analytical expressions. The results depict that both the network and channel parameters that include the fading parameter, the density of the eavesdroppers, the average SNR of the B-to-U link, the average SNR of the U-to-E link, the UAV altitude, and the coverage radius have a significant influence on the network secrecy performance. Full article

A rapid and high-quality single-nucleotide polymorphisms (SNPs)-based method was developed to improve detection and reduce salmonellosis burden. In this study, whole-genome sequence (WGS) was used to investigate SNPs, the most common genetic marker for identifying bacteria. SNP-sites encompassing 15 sets of primers (666–863 bp) were selected and used to amplify the target Salmonella serovar strains, and the amplified products were sequenced. The prevalent Salmonella enterica subspecies enterica serovars, including Typhimurium; Enteritidis, Agona, enterica, Typhi, and Abony, were amplified and sequenced. The amplified sequences of six Salmonella serovars with 15 sets of SNP-sites encompassing primers were aligned, explored SNPs, and SNPs-carrying primers (23 sets) were designed to develop a multiplex PCR marker (m-PCR). Each primer exists in at least two SNPs bases at the 3′ end of each primer, such as one was wild, and another was a mismatched base by transition or transversion mutation. Thus, twenty-three sets of SNP primers (242–670 bp), including 13 genes (SBG, dedA, yacG, mrcB, mesJ, metN, rihA/B, modA, hutG, yehX, ybiY, moeB, and sopA), were developed for PCR confirmation of target Salmonella serovar strains. Finally, the SNPs in four genes, including fliA gene (S. Enteritidis), modA (S. Agona and S. enterica), sopA (S. Abony), and mrcB (S. Typhimurium and S. Typhi), were used for detection markers of six target Salmonella serotypes. We developed an m-PCR primer set in which Salmonella serovars were detected in a single reaction. Nevertheless, m-PCR was validated with 21 Salmonella isolates (at least one isolate was taken from one positive animal fecal, and n = 6 reference Salmonella strains) and non-Salmonella bacteria isolates. The SNP-based m-PCR method would identify prevalent Salmonella serotypes, minimize the infection, and control outbreaks. Full article

Salmonella is a Gram-negative bacterium known to be the major cause of gastrointestinal diseases and systemic infections. During infection of murine B cells, Salmonella activates the PI3K/Akt pathway through its effector, SopB. This signaling pathway induces the downregulation of NLRC4 transcription, resulting in reduced secretion of IL-1β. Thus, Salmonella-infected B cells do not progress to pyroptosis; consequently, the bacteria can survive inside these cells. However, the mechanism by which Salmonella evades the control of B cells has not yet been elucidated. In this study, we found that SopB activates mTORC1, which is necessary for bacterial survival, since B cells cultured with the mTORC1 inhibitor rapamycin and B cells lacking raptor can control Salmonella infection. A similar result was observed in B cells when they were infected with the Salmonella SopB mutant (Δsopb). Salmonella also promoted the phosphorylation of the ULK1 complex at serine 757 (Ser757) by mTORC1, resulting in decreased levels of LC3-II in infected B cells. In this study, we did not observe these results when B cells were infected with Δsopb Salmonella. Our results demonstrated that Salmonella survival within B cells depends on the inhibition of autophagy by mTORC1 activation. Full article

An echelon-use lithium-ion battery (EULB) refers to a powered lithium-ion battery used in electric vehicles when the battery capacity is attenuated to less than 80% and greater than 20%. Aiming at the degradation of the performance of the EULB and the unclear initial value of the state of energy (SOE), estimations of the state of power (SOP) of an EULB are not accurate. An SOP estimation method based on an adaptive dual unscented Kalman filter (ADUKF) is proposed. First, the second-order resistor-capacitance symmetry equivalent model (SRCSEM) of the EULB is established. Second, an unscented transformation (UT) is introduced and the battery parameters estimated by the ADUKF: (a) the SOE is estimated based on an adaptive unscented Kalman filtering (AUKF) algorithm, that uses the observation noise equation γ_k, R_k and the processes noise equation q_k, Q_k, and (b) the ohmic internal resistance (OIR) and actual capacity (AC) are estimated based on the aforementioned algorithm, which uses the observation noise equation γ_θ,k, R_θ,k and the process noise equation q_θ,k, Q_θ,k. Third, the working voltage and OIR are predicted using optimal estimation, and the SOP of the EULB is estimated. MATLAB simulation results show that EULB symmetry capacity decays to 80%, 60%, 40%, and 20% of rated capacity, the proposed algorithm is adaptive regardless of whether the initial SOE value is consistent with the actual value, and the estimation error of the EULB’s SOP is less than 3.28%, showing high accuracy. The results of this study can provide valuable reference for estimating EULB parameters, and help to understand the usage behavior of retired batteries. Full article

This study was undertaken to determine the virulence, antimicrobial resistance and molecular subtypes of Salmonella in the Central Region of Peninsular Malaysia. A total of 45 Salmonella Enteritidis were detected from live chicken (cloacal swab), and chicken products (fresh and ready-to-eat meat) samples upon cultural isolation and serotyping. Similarly, an antimicrobial susceptibility test based on the Kirby Bauer disk diffusion method as well as antimicrobial resistance AMR genes, virulence determinants and multilocus sequence typing (MLST) typing were conducted after the Whole Genome Sequencing and analysis of the isolates. The results indicate that sequence types ST1925 (63.7%), and ST11 (26.5%) were the predominant out of the seven sequence types identified (ST292, ST329, ST365, ST423 and ST2132). The phenotypic antimicrobial profile corresponds to the genotypic characterization in that the majority of the isolates that exhibited tetracycline, gentamycin and aminoglycoside resistance; they also possessed the tetC and blaTEM β-Lactam resistance genes. However, isolates from cloacal swabs showed the highest number of resistance genes compared to the chicken products (fresh and ready-to-eat meat) samples. Furthermore, most of the virulence genes were found to cluster in the Salmonella pathogenicity island (SPI). In this study, all the isolates were found to possess SPI-1, which codes for the type III secretion system, which functions as actin-binding proteins (SptP and SopE). The virulence plasmid (VP) genes (spvB, spvC) were present in all genotypes except ST365. The findings of this study, particularly with regard to the molecular subtypes and AMR profiles of the Salmonella Enteritidis serotype shows multidrug-resistance features as well as genetic characteristics indicative of high pathogenicity. Full article

Salmonella enterica is one of the most common causes of foodborne illness worldwide. Contaminated poultry products, especially meat and eggs are the main sources of human salmonellosis. Thus, the aim of the present study was to determine prevalence, antimicrobial resistance profiles, virulence, and resistance genes of Salmonella Enteritidis (S. enteritidis) and Salmonella Typhimurium (S. Typhimurium) isolated from laying hens, table eggs, and humans, in Sharkia Governorate, Egypt. The antimicrobial activity of Biosynthesized Silver Nanoparticles (AgNPs) was also evaluated. Salmonella spp. were found in 19.3% of tested samples with laying hens having the highest isolation rate (33.1%). S. Enteritidis) (5.8%), and S. Typhimurium (2.8%) were the dominant serotypes. All isolates were ampicillin resistant (100%); however, none of the isolates were meropenem resistant. Multidrug-resistant (MDR) was detected in 83.8% of the isolates with a multiple antibiotic resistance index of 0.21 to 0.57. Most isolates (81.1%) had at least three virulence genes (sopB, stn, and hilA) and none of the isolates harbored the pefA gene; four resistance genes (blaTEM, tetA, nfsA, and nfsB) were detected in 56.8% of the examined isolates. The AgNPs biosynthesized by Aspergillus niveus exhibit an absorption peak at 420 nm with an average size of 27 nm. AgNPs had a minimum inhibitory concentration of 5 µg/mL against S. enteritidis and S. typhimurium isolates and a minimum bactericidal concentration of 6 and 8 µg/mL against S. enteritidis and S. typhimurium isolates, respectively. The bacterial growth and gene expression of S. enteritidis and S. typhimurium isolates treated with AgNPs were gradually decreased as storage time was increased. In conclusion, this study indicates that S. enteritidis and S. typhimurium isolated from laying hens, table eggs, and humans exhibits resistance to multiple antimicrobial classes. The biosynthesized AgNPs showed potential antimicrobial activity against MDR S. enteritidis and S. typhimurium isolates. However, studies to assess the antimicrobial effectiveness of the biosynthesized AgNPs in laying hen farms are warranted. Full article

Owing to the degradation of the performance of a retired battery and the unclear initial value of the state of charge (SOC), the estimation of the state of power (SOP) of an echelon-use battery is not accurate. An SOP estimation method based on an adaptive dual extended Kalman filter (ADEKF) is proposed. First, the second-order Thevenin equivalent model of the echelon-use battery is established. Second, the battery parameters are estimated by the ADEKF: (a) the SOC is estimated based on an adaptive extended Kalman filtering algorithm, that uses the process noise covariance $Q_k$ and observes the noise covariance $R_k$ , and (b) the ohmic internal resistance and actual capacity are estimated based on the aforementioned algorithm, that uses the process noise covariance $Q_{\theta ,k}$ and observes the noise covariance $R_{\theta ,k}$. Third, the working voltage and internal resistance are predicted using optimal estimation, and the SOP of the echelon-use battery is estimated. MATLAB simulation results show that, regardless of whether or not the initial value of the SOC is clear, the proposed algorithm can be adjusted to the adaptive algorithm, and if the estimation accuracy error of the echelon-use battery SOP is less than 4.8%, it has high accuracy. This paper provides a valuable reference for the prediction of the SOP of an echelon-use battery, and will be helpful for understanding the behavior of retired batteries for further discharge and use. Full article