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Fish body measurement is essential for monitoring fish farming and evaluating growth. Non-destructive underwater measurements play a significant role in aquaculture management. This study involved annotating images of fish in aquaculture settings and utilized a line laser for underwater distance calibration and fish body inclined-angle calculation. The YOLOv8 model was employed for fish identification and key-point detection, enabling the determination of actual body dimensions through a mathematical model. The results show a root-mean-square error of 6.8 pixels for underwater distance calibration using the line laser. The pre-training YOLOv8-n, with its lower parameter counts and higher MAP values, proved more effective for fish identification and key-point detection, considering speed and accuracy. Average body length measurements within 1.5 m of the camera showed a minor deviation of 2.46% compared to manual measurements. The average relative errors for body length and width were 2.46% and 5.11%, respectively, with corresponding average absolute errors. This study introduces innovative techniques for fish body measurement in aquaculture, promoting the digitization and informatization of aquaculture processes. [ABSTRACT FROM AUTHOR]

Aiming at the challenges to the accurate and stable heading control of underactuated unmanned surface vehicles arising from the nonlinear interference caused by the overlay and the interaction of multi interference, and also the uncertainties of model parameters, a heading control algorithm for an underactuated unmanned surface vehicle based on an improved backpropagation neural network is proposed. Based on applying optimization theory to realize that the underactuated unmanned surface vehicle tracks the desired yaw angle and maintains it, the improved momentum of weight is combined with an improved tracking differentiator to improve the robustness of the system and the dynamic property of the control. A hyperbolic tangent function is used to establish the nonlinear mappings an approximate method is adopted to summarize the general mathematical expressions, and the gradient descent method is applied to ensure the convergence. The simulation results show that the proposed algorithm has the advantages of strong robustness, strong anti-interference and high control accuracy. Compared with two commonly used heading control algorithms, the accuracy of the heading control in the complex environment of the proposed algorithm is improved by more than 50%. [ABSTRACT FROM AUTHOR]

To eliminate the measurement errors of insulation parameters caused by the internal impedance of VT (voltage transformer) and the damping resistance in resonant grounding distribution networks, a new online measurement technology based on an extended zero-sequence circuit is proposed. A constant current signal with variable frequency is injected into distribution network through a VT, and the return voltage is measured from another unloaded VT. An extended zero-sequence circuit is established to ensure that the injected current and the return voltage directly act on the insulation branch to ground; thus, the influence of the VT internal impedance can be eliminated. The resonance frequency is obtained according to the phase difference between the injected current and the return voltage, and the measurement error caused by damping resistance can be eliminated. Then, the capacitance to ground and leakage conductance can be accurately calculated. A measuring device based on the proposed technology was developed, and tests were carried out on a 10-kV distribution network laboratory and an actual 10-kV substation. The test results show that the proposed method has high measurement accuracy. The measurement process does not require a power interruption, and it does not affect the normal operation of the power system. [ABSTRACT FROM AUTHOR]

• Complex seawater leads to challenge to stability and activity of HER catalyst. • Adverse corrosion, precipitation and deposition are harmful to HER catalyst. • Four strategies on structure, polyanion, coating, and nanostructure are outlined. • With great progress, deficient stability and unclear mechanism hinder development. • Four outlooks from inner and outer of catalysts have been presented for research. Hydrogen is the ideal energy to resolve the depletion and shortage of fossil fuel. Seawater electrolysis to hydrogen has been considered the strategic direction for large-scale hydrogen production in the future. The cathodic hydrogen evolution reaction (HER) electrocatalyst is vital to the seawater electrolysis efficiency. However, the complex seawater causes the detrimental side reactions of corrosion, precipitation and deposition reactions to the HER electrocatalysts. To overcome these adverse effects, four efficient strategies of stable structure, polyanion passivating layer, protective coating, and unique nanostructure have been developed. These strategies could effectively repel Cl−, strengthen corrosion resistance, and prevent precipitates/deposits adhesion. Therefore, the stability and activity retention of the HER electrocatalysts for seawater electrolysis have been significantly improved. However, the problems of low stability, unclear electrocatalyst structure and reaction mechanism, inactive and unstable coating, as well as inferior performances to industrial requirement hinder the development of seawater electrocatalysts on HER. Then, the outlooks have been put forward for future research. Exploration of super-stable electrocatalysts, verifying reconstructed structures and reaction mechanism, utilization of ion exchange membranes, optimization outer environment of electrocatalysts would boost the development of seawater electrocatalysts and large-scale hydrogen production, benefitting mankind to achieve the "dual carbon goals". [ABSTRACT FROM AUTHOR]

[Display omitted] • High-valence Mo/Mn-doped amorphous MoMn-NiCoS is made by pulse electrodeposition. • MoMn-NiCoS is one bifunctional catalyst for alkaline water/seawater splitting. • MoMn-NiCoS shows high activity, robust stability, and corrosion resistance. • Electron structure modulation/surface reconstruction/amorphous phase are vital. • MoMn-NiCoS offers a wise strategy for design/development of efficient catalyst. Alkaline water/seawater electrolysis has drawn broad concern for green hydrogen production. Design and development of efficient, stable, and inexpensive bifunctional catalysts is one great bottleneck to overall alkaline water/seawater splitting. Herein, high-valence Mo, Mn co-doped amorphous bimetallic sulfide (MoMn-NiCoS) was prepared by facile pulse electrodeposition technology. High-valence Mo, Mn significantly enhanced the bifunctional catalytic performances for elevated reaction kinetics and rapid charge transfer with optimal electron structure modulation. Therefore, MoMn-NiCoS exhibited excellent bifunctional performances with low overpotentials of 70/69/73 mV and 247/226/282 mV at 10 mA cm−2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline water/simulated seawater/natural seawater, respectively. Besides, MoMn-NiCoS||MoMn-NiCoS electrolyzers required small cell voltages of 1.57/1.56/1.62 V to reach 10 mA cm−2 for overall alkaline water/simulated seawater/natural seawater splitting. Moreover, MoMn-NiCoS performed prominent stability during the 50 h-chronopotentiometry test at 50 mA cm−2 for the electrolyzer. Meanwhile, NiCo-based hydroxides/oxyhydroxides and sulfate ions were formed for electrocatalyst surface reconstruction during catalytic process, which were beneficial to the excellent bifunctional electrocatalytic activities and chloride repulsion. No hypochlorite formation verified the superior chloride oxidation inhibition of MoMn-NiCoS. The excellent catalytic performances of MoMn-NiCoS were attributed to the high-valence dual-cation doping, amorphous structure, electron structure modulation, synergetic effect, and surface reconstruction. This work provided an insightful strategy for the design and development of high-efficiency, stable, and cost-effective bifunctional electrocatalysts for overall alkaline water/seawater electrolysis. [ABSTRACT FROM AUTHOR]

The more trials that are performed, the more accurate the results of HT ht determination will be. The new parameter HT ht of several soils is compared with the original paper in Fig. In this discussion, a new parameter HT ht is proposed to evaluate the strength anisotropy. [Extracted from the article]

Hadal trenches extend below 6000 m water depth. The high hydrostatic pressures occurring in the trenches (>60 MPa) create unfriendly for life conditions. Here, we isolated 55 fungal strains from hadal (>6000 m) and non-hadal (∼3500 m and 5500 m) sediments from the Mariana Trench using different pressure incubation experiments. The fungal strains that were successfully isolated, were assigned to Ascomycota (14 genera/25 species) and Basidiomycota taxa (5 genera/5 species). Among them, 41 fungal strains (38 isolates from Ascomycota and 3 isolates from Basidiomycota) were able to grow at hydrostatic pressures of 20 MPa, while 3 of these strains maintained successful growth at 60 MPa, which resembles the hydrostatic pressure at 6000 m water depth. Whole-genome sequencing and physiological activity data from two fungal isolates (Penicillium bialowiezense A30 and Cladosporium colombiae 601) growing at 20 MPa highlight the metabolic potential of fungal piezotolerants from the Mariana Trench in carbon (e.g., carbohydrate metabolism), nitrogen (e.g., assimilatory nitrate reduction) and sulfur (e.g., assimilatory sulfate reduction) cycling. Overall, our study demonstrates the existence of piezotolerant fungi from the Mariana Trench that can grow successfully under hydrostatic pressures of 20–60 MPa and highlights their potential ecological and metabolic functions in deep sea and hadal trench ecosystems. • 55 fungi strains have been isolated from Mariana Trench sediments. Among them, 41 strains under 20 MPa and 3 strains under HHP up to 60 MPa showed apparent growth. • This research has demonstrated the existence of piezotolerant fungi, provided fungal biomaterials for mycology, and further explored the ecological function of fungi in hadal trench ecosystems. [ABSTRACT FROM AUTHOR]

This study investigated the prevalence of antimicrobial resistant Enterococcus faecalis ( E. faecalis ) from ducks at slaughterhouses, analyzed antimicrobial resistance genes and virulence-associated genes of the isolates. Multilocus sequence typing (MLST) was performed to characterize their molecular characteristics. A total of 227 E. faecalis isolates (67.8%) were obtained from cecum (n = 114), cloaca (n = 50), skin (n = 59), and rinsed water (n = 4). These E. faecalis exhibited high level of resistance against tetracycline (95.6%), doxycycline (94.3%), linezolid (75.8%), erythromycin (72.2%), followed by norfloxacin (56.8%), vancomycin (38.3%), penicillin (36.1%), teicoplanin (30.8%). Lower level of resistance was found to high-level streptomycin (19.8%), imipenem (15.9%) and high-level gentamicin (5.7%). The vast majority of isolates (90.3%) were multidrug resistant (MDR). Moreover, the commonly observed resistance genes were optrA (90.7%) and ermB (90.3%), followed by aph(3')-Ⅲ (86.8%), tetM (84.6%), acc(6')-aph(2) (77.5%), blaZ (76.7%) and aac(6')-Ie-aph(2")-Ia (75.8%). The less frequently observed genes were vanC (19.8%), blaTEM (4.8%), vanM (2.6%), and vanA (0.4%). None of the strains carried aph(2")-Ic and vanB genes. Furthermore, a high prevalence of ten virulence determinants was identified, and efaA (99.1%) was predominant, followed by eep (97.4%), srtA (96.9%), asa1 (95.6%), fsrB (92.1%), sprE (89.9%), aggA (63.9%), gelE (56.4%), esp (33.9%), and cylL (15.4%). Eleven isolates (4.9%) co-carried all of the tested virulence-associated genes. MLST analysis demonstrated that, E. faecalis isolates consisted of 12 known STs and 5 new STs, among which 6 of the identified STs were associated with nosocomial infection. Our data indicated that retail ducks serve as an important source of MDR E. faecalis with high pathogenicity potential, and suggested that transmission to humans could not be excluded. [ABSTRACT FROM AUTHOR]

Aimed at the problems that the multi-workstation revolver of ultra high-speed packaging machine had high motion inertia impact and high structure dynamic characteristics under the condition of large dead weight, ultra high-speed rotation and complex multi-workstation load. The paper analyzed the working load and constraint condition of multi-workstation revolver under rated working condition, and the finite element analysis model was constructed by using ANSYS Workbench platform, and the optimal topology optimization material distribution characteristics of multi-workstation revolver in the design domain was calculated with topology optimization technology, and based on the topology optimization density map and 3D model, two optimized schemes were constructed by the structure scheme of gradient ring band and stiffener and the structure scheme of gradient arc groove and weight reduction hole respectively with symmetric structure. The results showed that the structure scheme of gradient ring band and stiffener is optimal, which can be meet the static and structural natural frequency requirements under proper working load at the same time, compared with the prototype design, the quality of the optimal structure scheme is reduced by 16. 33%, and the maximum equivalent stress of the optimal structure scheme is reduced by 11.25%, and the dynamic specific stiffness efficiency of the optimal structure scheme is increased by 4.14%. [ABSTRACT FROM AUTHOR]

Rodents have been extensively used as animal models in microbiome studies. However, all rodents have a habitual nature called coprophagy, a phenomenon that they self‐reinoculate feces into their gastrointestinal tract. Recent studies have shown that blocking coprophagy can alter rodents' diversity of gut microbiota, metabolism, neurochemistry, and cognitive behavior. However, whether rodents' coprophagy behavior affects the levels of inflammation and depression is unclear. In order to address this problem, we first blocked coprophagy in healthy mice. It displayed an increase in the levels of depression, verified by depressive‐like behaviors and mood‐related indicators, and inflammation, verified by the increased levels of the pro‐inflammatory cytokine, in coprophagy‐blocked mice. Furthermore, we transplanted fecal microbiota from chronic restraint stress (CRS) depression model mice and lipopolysaccharide (LPS) inflammation model mice to healthy recipient mice, respectively. It showed that the disease‐like phenotypes in the coprophagy‐blocked group were worse than those in the coprophagy‐unblocked group, including severer depressive symptoms and higher levels of pro‐inflammatory cytokines (IL‐1β, IL‐6, TNF‐α and IFN‐γ) in serum, prefrontal cortex (PFC), and hippocampus (HIP). These findings showed that blocking coprophagy in mice not only increased the levels of inflammation and depression in healthy mice but also aggravated inflammation and depression induced by fecal microbiota from disease donors. The discovery may provide a vital reference for future research involving FMT in rodents. [ABSTRACT FROM AUTHOR]

Excessive amounts of fluoride in water cause irreversible harm to people and seriously threaten human health. Therefore, fluoride ion in water should be deeply removed. The waste liquor of itaconic acid fermentation contains many organic acids, residual sugars, proteins, and other impurities, which are difficult to remove. Thus, in this study, the itaconic acid fermentation waste liquid was successfully mixed with urea to prepare N-doped porous carbon (PC-N). The prepared PC-N was applied for the removal of fluoride in water. The specific surface area of PC-N is as high as 1803 m2 g−1, and the SEM results show an abundant pore structure. The FTIR results showed that the adsorbent surface had an abundant functional group structure. The removal rate of F− by PC-N was 91% when pH = 6. After 6 cycles of recycling, PC-N performance remains stable at about 73% of that of the fresh adsorbent. Moreover, Freundlich and PSO can better fit the adsorption data, indicating that F− on PC-N adsorption results from the joint action of physical and chemical adsorption. After calculating the adsorption thermodynamics, ΔH and ΔS are −14.5529 kJ mol−1 and 13.6507 J (mol K)−1, and ΔG is negative, indicating that the adsorption process is exothermic and spontaneous. The outcome results of this work have achieved the goal of "treating waste with waste" and realized the dual protection of the environment. [ABSTRACT FROM AUTHOR]

In this paper, a novel dynamic surface sliding mode control (DSSMC) method, combined with a lateral velocity tracking differentiator (LVTD), is proposed for the cooperative formation control of underactuated unmanned surface vehicles (USVs) exposed to complex marine environment disturbances. Firstly, in view of the kinematic and dynamic models of USVs and the design idea of a virtual control law in a backstepping approach, the trajectory tracking control problem of USVs' cooperative formation is transformed into a stabilisation problem of the virtual control law of longitudinal and lateral velocities. Then, aiming at the problem of differential explosion caused by repeated derivation in the process of backstepping design, the first-order low-pass filter about the virtual longitudinal velocity and intermediate state quantity of position is constructed to replace differential calculations during the design of the control law, respectively. In order to reduce the steady-state error when stabilising the virtual lateral velocity control law, the integral term is introduced into the design of the sliding mode surface with a lateral velocity error, and then the second-order sliding mode surface with an integral is structured. In addition, due to the problem of controller oscillation and the role of the tracking differentiator (TD) in active disturbance rejection control (ADRC), the LVTD is designed to smooth the state quantity of lateral velocity. Subsequently, based on the dynamic model of USV under complex marine environment disturbances, the nonlinear disturbance observer is designed to observe the disturbances and compensate the control law. Finally, the whole cooperative formation system is proved to be uniformly and ultimately bounded, according to the Lyapunov stability theory, and the stability and validity of the method is also verified by the simulation results. [ABSTRACT FROM AUTHOR]

The Gram-negative rod-shaped bacterium Serratia marcescens is an opportunistic pathogen of many organisms, including insects. We report the identification and optimal in vitro chitinase production conditions of a novel chitinolytic S. marcescens strain TC-1 isolated from a naturally infected white grub (Anomala corpulenta) collected from a peanut field at Nanyang city, Henan province, China. Strain identification was conducted by morphological, physiological, biochemical and molecular analyses. The amplified 16S rRNA gene of TC-1 showed a similarity greater than 99% with multiple strains of S. marcescens. Based on Neighbor-joining phylogenetic tree analysis of bacterial 16S rRNA gene sequences, TC-1 formed a clade with S. marcescens, clearly separated from other Serratia spp. The strain TC-1 showed larvicidal activities against five insect species (A. corpulenta, Plutella xylostella, Spodoptera exigua, Helicoverpa armigera, Bombyx mori) and the nematode Caenorhabditis elegans, but not against S. litura. The operating parameters of chitinase production by TC-1 were optimized by response surface methodology using a three-factor, three-level Box-Behnken experimental design. The effects of three independent variables i.e. colloidal chitin concentration (7–13 g l−1), incubation time (24–72 h) and incubation temperature (24–32 °C) on chitinase production by TC-1 were investigated. A regression model was proposed to correlate the independent variables for an optimal chitinase activity predicted as 20.946 U ml−1, using a combination of colloidal chitin concentration, incubation time and incubation temperature of 9.06 g l−1, 63.83 h and 28.12 °C, respectively. The latter agreed well with a mean chitinase activity of 20.761 ± 0.102 U ml−1 measured in the culture supernatants of TC-1 grown under similar conditions with a colloidal chitin concentration, incubation time and incubation temperature of 9 g l−1, 64 h and 28 °C, respectively. Our study revealed the S. marcescens strain TC-1 with potential as a biocontrol agent of insect pests and nematodes and demonstrated the proposed regression model's potential to guide chitinase production by this strain. [ABSTRACT FROM AUTHOR]

A total of 220 Campylobacter isolates was recovered from 656 samples along a commercial duck slaughter line after a panel of confirmation tests including selective culture methods, biochemical identification and multiplex PCR in southwestern China. The prevalence of Campylobacter spp. was 33.5%, including 16.6% of Campylobacter jejuni , 15.7% of Campylobacter coli and 3.6% of other Campylobacter species. A high level of resistance was observed to tetracycline (96.4%) and clindamycin (92.3%), followed by azithromycin (66.8%), erythromycin (47.3%), nalidixic acid (44.5%), chloramphenicol (42.7%), gentamicin (41.4%), and ciprofloxacin (37.3%). Forty-seven classes of antimicrobial resistance profile were found, and multidrug resistant (MDR) strains occupied 75.9% of the Campylobacter isolates. Virulence-associated genes of cadF (100%), cheY (92.7%) and cdtB (92.3%) were commonly observed in the Campylobacter isolates, followed by flaA (77.2%), iamA (71.8%), cdtA (60%), cdtC (54.1%) and ciaB (42.7%). Virulence gene of virB11 (7.7%) was less frequently detected. Totally, 48 virulence gene profiles were generated among Campylobacter isolates. Our results confirmed the prevalence of Campylobacter spp. in the duck slaughterhouse, which were MDR and harbored several putative virulence-associated genes that might pose harm to human. • Duck is a vital reservoir for Campylobacter species, which has a potential risk to public health. • Prevalence of Campylobacter jejuni was slightly dominant than Campylobacer coli in duck slaughterhouse. • Campylobacter spp. was resistant to multiple antimicrobial agents with high MIC values. • Antimicrobial resistance of C. coli was higher than that of C. jejuni in duck slaughterhouse. • C. jejuni harbored more virulence-associated genes than C. coli. [ABSTRACT FROM AUTHOR]

In order to eliminate the common carbide networks in Fe-Cr-C tool steel, a low-cost Fe-Cr-C steel with high hardness and high toughness was designed. Correspondingly, a multistage heat treatment process is also designed. Multistage heat treatment includes homogenization, spheroidizing annealing, quenching and low temperature tempering. Compared to AISI D2 steel (58–62HRC, 24.3–27.9 J/cm2), the designed steel maintains high hardness (60.5HRC) and higher unnotched impact toughness (46.2 J/cm2). The hardening and toughening mechanisms of the designed Fe-Cr-C steel were studied by mechanical properties testing, multi-scale characterization and thermodynamic calculation. Experimental results show that the complete austenite phase region of Fe-Cr-C steel is the key factor to eliminate carbide networks by homogenization treatment. The gradient scale M 7 C 3 produced by the spheroidizing annealing and quenching enhances the hardening effect through refining prior austenite grains size, promoting martensite nucleation, and limiting martensite growth. During the low temperature tempering, volume fraction reduction of retained austenite weakens the transformation induced plasticity (TRIP) effect and softens martensite, which is beneficial to improve the toughness. Finally, the decomposition of twinning martensite caused by nanoscale θ-Fe 3 C precipitation and the precipitation hardening of nanoscale θ-Fe 3 C play important role in maintaining hardness and improving toughness. • A novel low-cost Fe-Cr-C steel and its multi-stage heat treatment were designed to achieve high hardness and toughness. • The carbide networks are completely eliminated, and the carbides with a diffuse and gradient scale are obtained. • After tempering, the weaken of TRIP effect and martensite softening are important reasons for the increase of toughness. • The decomposition of martensite mechanical twins due to the precipitation behavior of θ-Fe3C is also improve the toughness. [ABSTRACT FROM AUTHOR]

A dual model predictive control (DMPC) method based on virtual trajectory is proposed in this paper, in order to achieve autonomous cooperative formation control of underactuated unmanned surface vehicles (USVs) in complex ocean environment. Firstly, the formation tracking error model of the USVs is designed, and considering the large initial state tracking error of USVs, a virtual transition trajectory is put forward to guide the design of tracking controller. To solve the mutation problem caused by misalignment of the follower USV's desired trajectory in the early stage, an improved differential tracker is introduced into virtual leader USV to smooth the desired trajectory of the follower USV. In addition, a dual mode switching strategy is designed to decide when and how to quit the transition of the virtual USV. A nonlinear disturbance observer is introduced to compensate the complex marine environment interference. Finally, by introducing terminal penalty function and linear state feedback controller, the Lyapunov function is constructed to prove the control stability of the proposed model predictive control method in finite time domain, and the effectiveness and reliability of the proposed method are verified by simulation experiments. • A dual MPC method based on virtual USV trajectory is proposed for the cooperative formation control of USVs. • An improved differential tracker is introduced into virtual leader USV to smooth the desired trajectory of the follower. • A dual-mode switching strategy is designed to select which trajectory as the USVs' tracking trajectory. [ABSTRACT FROM AUTHOR]

• The complex gradient microstructure evolution of carburized carbon steel under multi-step heat treatment was studied. • A novel heat treatment method for carburized steel was proposed and the hardness of carburized layer was increased. • The hardening mechanism of carburized layer by novel heat treatment method was discussed. The microstructure evolution of 15MnNi4Mo steel after carburizing was studied, and the hardening mechanism of carburized layer under the influence of sub-temperature quenching was discussed. The results show that due to the high Ni content, the high-temperature tempering process of 15MnNi4Mo is slow, and the carburizing layer evolution behavior is mainly the decomposition of martensite and retained austenite, while the heart region is mainly the decomposition of M/A island. The sub-temperature quenching retains some of the carbides after tempering which increases the hardness (60HV) of the carburized layer by reducing the retained austenite, refining the substructures of martensite and accumulating dislocations around carbides. [ABSTRACT FROM AUTHOR]

The prevalence and diversity of Salmonella spp. was investigated along the duck slaughter line in Sichuan Province of China from May 2016 to July 2017. A total of 156 Salmonella isolates were recovered out of 523 samples with an overall prevalence of 27.3%, and high prevalence was observed in caecal samples (43.5%) and carcasses after defeathering (27.0%). Eleven different serotypes were confirmed, among which S. Indiana, S. Newlands and S. Newport were commonly observed serotypes. Resistance was most frequently observed against nalidixic acid (94.2%), followed by ampicillin (59.6%), tetracycline (51.3%) and trimethoprim/sulfisoxazole (46.2%) with a medium resistance level. Resistance to ciprofloxacin (27.6%), minocycline (20.5%) and kanamycin (19.2%) was less commonly detected. Among the Salmonella isolates, 98.1% of the strains were resistant to at least one antimicrobial agent and 63.5% of the isolates were classified as multidrug resistant (MDR). The top five virulence-associated genes were ssaQ (94.2%), avrA (92.3%), mgtC (92.3%), bcfC (87.2%) and siiD (84.6%). All of the Salmonella isolates harbored at least one virulence-associated gene, and 142 (91.0%) isolates co-harbored at least five virulence-associated genes. In addition, pulsed-field gel electrophoresis (PFGE) subtyping generated 41 PFGE patterns with a similarity index ranging from 33.8% to 99.1%. The majority of Salmonella isolates with same serovars or from same visit tended to cluster into identical pulsotypes, while a correlation among PFGE clusters, resistant profiles and virulotypes was not observed. The results revealed that Salmonella isolates from the duck slaughterhouse were not only genotype multiform, the majority of them were also multidrug resistant and co-carried multiple virulence-associated genes, which may pose potential risk to public health. • S. Indiana, S. Newlands and S. Newport were common serotypes. • Virulotypes of same serotype varied significantly with different combinations. • Correlation among PFGE clusters, resistance profiles and virulotypes was not observed. • Introduced Salmonella was the major factor implicated in contamination at the duck slaughterhouse. [ABSTRACT FROM AUTHOR]