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Backward erosion piping constitutes a major threat for dikes on sandy or silty foundations during high water and floods. This erosion mechanism results in the formation and development of shallow hollow spaces (pipes) at the interface between the impermeable top layer and the aquifer. Erosion at the tip of the pipe determines the progression of the pipe towards the upstream side. A valid criterion should be developed to predict the critical local gradient at which erosion at the pipe tip occurs. Based on the failure mode of the tip of the pipe that the erosion near the toe of the scarp of the pipe tip causes the collapse of the scarp, in combination with the seepage field near the pipe tip, analyses are conducted regarding the equilibrium of forces on single particles at the toe of the scarp and a group of particles of the scarp. The conditions for incipient motion for particles at the pipe tip are determined. And a novel criterion for predicting the critical local gradient at the pipe tip is developed, which is essential for assessing the risk of pipe progression in practice. [ABSTRACT FROM AUTHOR]

β-1,3/1,6-glucan as a prebiotic improves immune performance in animals. These functions are closely related to the effect of β-1,3/1,6-glucan on gut microbiota structure. However, the effect of β-1,3/1,6-glucan on the gut microbiota structure of broilers is unclear. The aim of this study was to confirm the effects of β-1,3/1,6-glucan on the cecal microflora structure of yellow-feathered broilers. This study monitored the antimicrobial resistance (AMR) level of Escherichia coli in feces of yellow-feathered broilers by standard broth dilution method and mastered the AMR level of chickens selected. The effects of β-1,3/1,6-glucan on gut microbiota were investigated by 16S rRNA sequencing. The results showed that the number of isolated multidrug-resistant E. coli strains accounted for 98.41%. At 14, 21, and 28 days of age, supplemented of 0.2%, 0.1%, and 0.1% β-1,3/1,6-glucan in yellow-feathered broiler diets significantly altered gut microbial composition, and beneficial bacteria Alistipes, Bacteroides and Faecalibacterium were significantly increased. These findings provide guidance and recommendations for β-1,3/1,6-glucan as a broiler feed additive to improve the growth of broilers. [ABSTRACT FROM AUTHOR]

A selective and reliable method was developed and validated for the determination of 14 lipophilic pesticides in raw propolis by gas chromatography–tandem mass spectrometry (GC-MS/MS) analysis. A test portion of milled sample was extracted with n-hexane followed by back extraction with acetonitrile and cleanup using EMR-Lipid and Florisil column adsorption. Matrix-matched standards were used to compensate for matrix effects. Typical linear correlation coefficients (R2) were ≥ 0.989 in concentration range of 0.001–0.200 μg/mL. Method validation was carried out at three spiking levels and three individual days, and it was found that the mean interday average recoveries were 61.0–106.8% with relative standard deviations ≤ 16.9%. Limits of quantification were ranged from 0.002 to 0.020 μg/g. Analysis of market propolis samples showed contamination by pesticides (e.g., tau-fluvalinate) to some degree. [ABSTRACT FROM AUTHOR]

Backward erosion piping is an important failure mechanism in both dikes and dams where uniform silts and sands are covered by a cohesive layer. It is an internal erosion mechanism during which shallow pipes are formed at the interface of the aquifer and the cohesive top layer in the direction opposite to the flow. The hydraulic conditions near the pipe tip determine the onset of erosion near the pipe tip, which causes pipe lengthening. The seepage field near the pipe tip was analysed using the analytical solutions. The two-dimensional (2D) analytical solution available for calculating the seepage field at the vertical section of the pipe tip in three-dimensional (3D) groundwater flow has been validated on the basis of experiments with 3D configurations. The motion characteristics of particles at the pipe tip were explained on the basis of the analysis of the effect of the ditch at the toe of the pipe tip on the hydraulic conditions near the pipe tip. The equilibrium of the soil in front of the pipe tip was analysed to determine the pressure distribution on the top of the sand layer in front of the pipe tip. The unified method for calculating the local critical hydraulic gradient at the pipe tip in both 2D and 3D experiments was proposed. The local critical hydraulic gradients at the pipe tip were analysed for the available experiments, indicating that the influences of grain diameter and scale on the local critical hydraulic gradient are limited, a finding that is essential for the development of a new model. [ABSTRACT FROM AUTHOR]

Backward erosion piping is a prominent failure mechanism in water-retaining structures. It is a phenomenon in which shallow pipes are formed in an upstream direction at the interface of a sandy aquifer and an impermeable top layer. Experiments were conducted at two different scales to investigate the erosion mechanism near the pipe tip that causes the pipe to lengthen at the grain scale. The erosion process of grains at the tip of the pipe was filmed from the top and the side. The observations and video recordings allowed for a better understanding of the features of the pipe tip. A zone of loosened sand grains was formed around the pipe during the pipe development. The extent of the loosened zone was determined by analysing the images captured during the lengthening of the pipe. The motion characteristics of particles at the pipe tip and the erosion mechanism near the pipe tip were obtained by analysing the erosion process observed. The findings can serve as a basis for the establishment of a criterion for pipe progression and the development of a novel piping prediction model. [ABSTRACT FROM AUTHOR]

Gut microbial diversity and the core microbiota of the Jinhua pig, which is a traditional, slow-growing Chinese breed with a high body-fat content, were examined from a total of 105 fecal samples collected from 6 groups of pigs at 3 weaning ages that originated from 2 strains and were raised on 3 different pig farms. The bacterial community was analyzed following high-throughput pyrosequencing of 16S rRNA genes, and the fecal concentrations of short-chain fatty acids (SCFAs) were measured by gas chromatograph. Our results showed that Firmicutes and Bacteroidetes were the dominant phyla, and Lactobacillus, Streptococcus, Clostridium, SMB53, and Bifidobacterium were the most abundant genera. Fifteen predominant genera present in every Jinhua pig sample constituted a phylogenetic core microbiota and included the probiotics Lactobacillus and Bifidobacterium, and the SCFA-producing bacteria Clostridium, Prevotella, Bacteroides, Coprococcus, Roseburia, Ruminococcus, Blautia, and Butyricicoccus. Comparisons of the microbiota compositions and SCFA concentrations across the 6 groups of pigs demonstrated that genetic background and weaning age affected the structure of the gut microbiota more significantly than the farm. The relative abundance of the core genera in the pigs, including Lactobacillus, Clostridium, Prevotella, Bacteroides, Roseburia, Ruminococcus, Blautia, and Butyricicoccus varied dramatically in pigs among the 2 origins and 3 weaning ages, while Oscillospira, Megasphaera, Parabacteroides, and Corynebacterium differed among pigs from different farms. Interestingly, there was a more significant influence of strain and weaning age than of rearing farm on the SCFA concentrations. Therefore, strain and weaning age appear to be the more important factors shaping the intestinal microbiome of pigs. [ABSTRACT FROM AUTHOR]

Most pathogens in intestine are opportunist, called 'opportunistic pathogens' that usually do not cause disease in a healthy host. Only when the host's resistance is lowered or the intestinal microecological balance is destroyed, the opportunistic pathogens are capable of causing disease. Here, two opportunistic pathogens, Salmonella enteritidis and Vibrio parahaemolyticus were chosen to test the possible antagonistic effect of the probiotic agent Clostridium butyricum on these pathogens infections in vitro using fish intestinal epithelial cells (FIECs). The C. butyricum and its spent culture supernatants exhibited significant inhibitory activity on S. enteritidis and V. parahaemolyticus growth and adherence to FIECs. The C. butyricum also showed significant inhibitory effects on S. enteritidis and V. parahaemolyticus induced apoptosis, which may due to its growth and adhesion inhibitory effects. These results indicated that the probiotic bacterium C. butyricum has preventive and therapeutic effects on S. enteritidis and V. parahaemolyticus infections in fish. [ABSTRACT FROM AUTHOR]

Myeloid differentiation factor 88 (MyD88) is an important adapter protein of the innate immune system, but it has never before been reported in yellow catfish (Pelteobagrus fulvidraco). In this study, we cloned and characterized the yellow catfish MyD88 gene. The gene was 1230 bp in length and contained an 876-bp open reading frame which encodes a polypeptide of 291 amino acid residues. The theoretical molecular mass and isoelectric point of this polypeptide were 33.4341 kDa and 5.17, respectively. Furthermore, bioinformatic and phylogenetic analyses grouped yellow catfish MyD88 with MyD88 of other fish. We found that the deduced amino acid sequence showed that the conserved N-terminal death domain and the C-terminal typical Toll/interleukin-1 receptor domain were very similar to those of other fish. Moreover, reverse transcription PCR showed that yellow catfish MyD88 is ubiquitously expressed in all tissues examined, with highest expression levels observed in the spleen and lowest levels in the intestine. Importantly, MyD88 was shown to be significantly up-regulated in the intestines after 30-day dietary supplement of Clostridium butyricum. Collectively, these results indicate that yellow catfish MyD88 has a conserved structure and is probably an important component of innate immunity in yellow catfish. This study is the first to identify and characterize MyD88 in yellow catfish, thereby providing a reference for further research into the yellow catfish innate immune system. [ABSTRACT FROM AUTHOR]