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When the upper part of a high gas coal seam has hard and thick sandstone roof, the gas explosion accident in goaf is even caused by roof collapse. Taking the mining of 1007 working face of 10 coal seam under Xia KuoTan Coal Mine as the engineering background, using the method of indoor experiment and theoretical analysis, the possibility of rock friction effect igniting gas is studied. Under the engineering geological conditions, the results show that the heat produced by the friction process of hard sandstone can ignite gas. According to the 3DEC numerical simulation, the instability characteristics of the overburden hard rock are studied. The results show that the size of the slab instability area is not changed when the length of the working face increases. When the thickness of the roof is increased, the area of sliding instability is increased and the degree of sliding instability is more intense. At the boundary of the tunnel, the overlying strata are subjected to the largest shear stress, and it tends to form a friction surface with greater slip instability.

The reliability of the computer numerical control (CNC) system affects its processing performance and is a major concern in the manufacturing industry today. However, existing reliability models to assess the reliability of the CNC system often exhibit relatively large errors due to inadequate treatment of small samples. In order to get around the constraint of limited lifetime failure data and take full advantage of existing reliability parameters in traditional reliability models, a multisource information fusion-based reliability model grounded on Bayesian inference is proposed to deal with the small sample size. The prior distributions are derived by using the probability encoding method and conjugate distribution based on the idea of multisource information fusion. Then, using the Jensen–Shannon divergence (JSD) to measure the similarity between prior information and field observation data, a constrained optimization problem is established to determine the respective weight of prior information and field observation data. Finally, by conducting the reliability analysis of repairable CNC systems, the validity of the proposed model and its prior distribution derivation method are verified.

At present, 3D printing technology is becoming more and more popular, but the traditional learning method has some limitations. The price of 3D printing equipment is expensive, and there are some security risks in the process of learning operation. This paper mainly introduces the development and process research of high-temperature environmental protection metal 3D printing equipment and realizes the design of 3D printing equipment combined with virtual reality technology. In this paper, the whole system of 3D printing equipment is designed and built. The function of motion platform and substrate in mechanical system is analyzed, and the detailed structure design is carried out; the control principle of control system including motion control system and temperature control system is introduced in detail, and the corresponding design and construction work is carried out. In this paper, the pure tin wire with low melting point was used as the experimental material, and the mechanical properties and microstructure of the metal tin forming parts were analyzed. On the basis of tin formation experiment, metal deposition experiment and metal forming error experiment were carried out with H65 high melting copper wire as the raw material. The experimental results show that when the printing speed is 35/mm, the dimensional accuracy of the products is high; the microhardness of the printed tin is close to that of the original material, the surface hardness is 12.50HV0.05, and that of the copper alloy is 14.31HV0.05; the tensile strength of tin wire after melt deposition is slightly reduced after tensile test for the machined tin parts, the ultimate tensile strength of the first group of specimens is reduced by 1.58%, and that of the second group is reduced by 0.74%. This paper combines virtual reality technology with 3D printing technology and develops 3D printing equipment for high-temperature environmental protection metal using virtual reality technology. The forming and printing performance of the device is analyzed theoretically and experimentally. The experimental results verify the feasibility of the system and the practicability of the device.

Background. Early detection appears to be the most effective approach to improve the overall survival of patients with hepatocellular carcinoma (HCC). We evaluated the potential performance of plasma SEPT9 methylation (mSEPT9) as a noninvasive biomarker for the diagnosis of patients with HCC. Methods. A total of 373 subjects were included, and the group consisted of 104 HCC patients, 95 with an at-risk disease, and 174 healthy controls (HC). The methylation of mSEPT9 was determined using methylation-specific fluorescence quantitative PCR. The diagnostic performance of plasma mSEPT9 for HCC was assessed in a single-blind manner. Results. The receiver operating characteristic (ROC) curve showed that plasma mSEPT9 can be used to detect and discriminate HCC with an area under the ROC curve (AUROC) of 0.961, a sensitivity of 82.7%, and specificity of 96.0% from HC. These results showed that plasma mSEPT9 had better diagnostic performance than serum alpha fetoprotein (AFP) (AUROC 0.881, sensitivity 57.7%, and specificity 98.3%). Similar results were noted in the detection of early-stage HCC. When combined with serum AFP, the sensitivity increased to 91.3% and 87.7% for the detection of HCC and early-stage HCC,respectively. Notably, the levels of plasma mSEPT9 dramatically decreased after surgery ( P = 0.001 ). Conclusions. Plasma SEPT9 methylation might serve as a useful and noninvasive biomarker for the diagnosis of HCC and can be used to evaluate the therapeutic efficacy of HCC treatment.

In the geological survey, the recognition and classification of rock lithology are an important content. The recognition method based on rock thin section leads to long recognition period and high recognition cost, and the recognition accuracy cannot be guaranteed. Moreover, the above method cannot provide an effective solution in the field. As a communication device with multiple sensors, smartphones are carried by most geological survey workers. In this paper, a smartphone application based on the convolutional neural network is developed. In this application, the phone’s camera can be used to take photos of rocks. And the types and lithology of rocks can be quickly and accurately identified in a very short time. This paper proposed a method for quickly and accurately recognizing rock lithology in the field. Based on ShuffleNet, a lightweight convolutional neural network used in deep learning, combined with the transfer learning method, the recognition model of the rock image was established. The trained model was then deployed to the smartphone. A smartphone application for identifying rock lithology was designed and developed to verify its usability and accuracy. The research results showed that the accuracy of the recognition model in this paper was 97.65% on the verification data set of the PC. The accuracy of recognition on the test data set of the smartphone was 95.30%, among which the average recognition time of the single sheet was 786 milliseconds, the maximum value was 1,045 milliseconds, and the minimum value was 452 milliseconds. And the single-image accuracy above 96% accounted for 95% of the test data set. This paper presented a new solution for the rapid and accurate recognition of rock lithology in field geological surveys, which met the needs of geological survey personnel to quickly and accurately identify rock lithology in field operations.

Summary The effect of water velocity on feeding of benthic cruising foragers, like sturgeons, is poorly understood. Using an artificial endless stream, we conducted experiments with wild juvenile Chinese Sturgeon, Acipenser sinensis, to test the hypothesis that water current speed affects juvenile feeding efficiency on the Barcheek Goby, Rhinogobius giurinus, a common wild prey. Feeding consumption (Fc) of juveniles was positively related to water current speed (current speed in cm−1: mean Fc value) follow: 0: 2.33; 11:7.33; 31: 10.67; and 41: 13.7. Thus, current speed had a significant effect on foraging efficiency by sturgeon. The results indicate foraging by wild A. sinensis juveniles on gobies occurs mostly during flood and neap tidal flows when current velocities are fastest.

Summary The hypothesis was tested that cryodamage occurs during the storage of semen at −196°C and that cryopreservation has a negative effect on the enzyme activity and motility of semen in the Russian sturgeon, Acipenser gueldenstaedtii. In addition, the aim of the study was to determine the activity of metabolic enzymes, including adenosintriphosphatase (total ATPase), creatine kinase (CK), succinate dehydrogenase (SDH) and lactate dehydrogenase (LDH), plus antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and glutathione reductase (GR). After cryopreservation (storage at −196°C), the motility and duration of semen fell and the total ATPase, SDH, LDH and CK activity in the spermatozoa was reduced. In the seminal plasma, however, total ATPase, SDH, LDH and CK activity increased markedly. Activity also notably increased in the group with no diluents or cryoprotectants. SOD, CAT and GSH-Px activities also increased in the seminal plasma but dropped with regard to the spermatozoa, whereas the GR activity varied. The antioxidant enzyme activity trend between the groups with and without the addition of cryoprotectants was the same as in the metabolic enzyme activity. Cryopreservation had a great effect on the enzyme activity and motility of A. gueldenstaedtii semen; however, the cryoprotectant protected the semen during cryopreservation.

Summary Male and female Amur sturgeon (Acipenser schrenckii) at sexual maturity (age 7 years) were identified under controlled breeding conditions, and the plasma biochemical parameters were determined at different developmental stages of the gonads. The results showed that there was significant difference of the plasma calcium (Ca2+) and lactate dehydrogenase (LDH) content between the sexually mature males and females. The LDH content in males was highest, while the Ca2+ concentration was lowest. During different gonad developmental stages (II,III,IV-A and IV-B) of the, the content in the ovaries of plasma total protein (TP), globulin (GLB), total bilirubin (TBIL), triglycerides (TRIG), Ca2+ and inorganic phosphorus (P−) initially showed an upward trend, and decreased thereafter. The values of albumin (ALB), albumin/globulin (A/G) and total cholesterol (CHOL) increased gradually from stage of II to IV-B, and showed significantly higher levels at the stage of IV-A to IV-B (P

Fish express a high degree of diversity in morphology, which is closely related to behaviors such as swimming ability. The effect of morphology on swimming performance is explored using geometric morphometric analyses and classic critical swimming speed (Ucrit) tests in Chinese sturgeon Acipenser sinensis and Siberian sturgeon A.baerii. It was found that A.sinensis is a stronger swimmer compared to A.baerii, with an average 25% higher Ucrit (expressed in body lengths per second). In A.sinensis, the depth and length of the snout and the trailing edge length of the dorsal fin were negatively correlated with Ucrit, whereas the height of the trunk anterior, the leading edge length of the dorsal fin and anal fin, and the length and width of the ventral lobe were positively related to Ucrit; similar relationships between Ucrit and morphological characters of the anterior trunk, dorsal fin, anal fin and caudal fin were found in A.baerii. Moreover, although the degree of upward bending of the snout of A.baerii was negatively related to Ucrit, there was a positive relationship between the length of the caudal peduncle and Ucrit as well as between the dorsal tail lobe and Ucrit. In addition, the streamline index (SI) was calculated by comparing landmark coordinates on the trunk displayed in the relative warp, with its corresponding point on the NACA (the U.S. National Advisory Committee for Aeronautics) airfoil shape. SI showed that the body shape in RW1 of the A.baerii with more swimming capacity was more approximate to the NACA 0016 airfoil shape, but there was no such symmetry for A.sinensis, possibly due to body bending caused by stiffness.

This study evaluated the uptake of fluoride ions (F−) in tissues of juvenile Siberian sturgeon (Acipenser baerii). Fish were fed diets containing 75.2 (Control), 162.6, 360.8, 710.2, 1478.3 mg F− kg−1 in triplicate for 12 weeks with F− added as NaF. Growth was inhibited in fish fed diets with 710.2 or 1478.3 mg F− kg−1, but was not inhibited in fish fed diets with 162.6 or 360.8 mg F− kg−1. The F− concentration in scute, cartilage, skin and gill increased with time and dietary F− concentration, and with the order of concentration at the end of the experiment, highest to lowest levels: scute (7721.3 mgF− kg−1), cartilage (2324.2), gill (721.4) and skin (262.5). Muscle, liver, gut and pylorus did not accumulate F− with increasing F− level in the diet. Thus, F− up to 360.8 mg F− kg−1 can be included in the Siberian sturgeon diet without an adverse effect on growth or survival. The F− as low as 162.6 mg F− kg−1 in diet increased F− concentrations in scute and cartilage, and the high concentration of F− in cartilage is possibly a danger to the consumption of cartilage in sturgeon.

Summary To determine the teratogenic effects of lead (Pb) on young Chinese sturgeon (A. sinensis), fertilized eggs (96-h) were exposed to Pb2+ until juvenile stages (total exposure 112 days). Three nominal concentrations were employed: 0.2 mg L−1, 0.8 mg L−1 and 1.6 mg L−1. After the exposure period, juveniles were returned to Pb-free water for a subsequent 42 days depuration period. Fish exposed to 0.8 and 1.6 mg L−1 Pb2+ exhibited body deformities during the exposure phase, appearing mainly as curvatures to left or right at OD (Origin of dorsal fin) to OC (Origin of the dorsal caudal fin), and OC to PC (Posterior margin of caudal fin) as well as to the OP (Origin of pectoral fin), associated with ptosis at PC. Moreover, the higher the concentration of water-borne Pb, the sooner body deformations occurred, while also affecting a larger proportion of the test individuals. Free locomotion and effective foraging was greatly reduced with increasing body deformation (lordosis). Pb accumulation in tissues was concentration dependent. Muscles accumulated relatively higher Pb which may have contributed to its effect on the muscle contraction potential and thus may have effected the neuromuscular system (muscle-induced body curvature). Morphological recovery decreased during the depuration period and this was accompanied by declining tissue Pb concentrations, indicating some self-repairing capacity.

Summary The toxicity of fluoride (F−) to Chinese sturgeon (Acipenser sinensis) larvae was investigated in combination with chloride (Cl−), hardness (Ca2+), and copper ions (Cu2+) within a 6 days test period, while F− concentrations were also monitored in the Yangtze Estuary for 1 year to assess the toxicity implications of environmental contamination load. The mean LC50 value (6 days) of F− was determined with 131.74 mg L−1 for Chinese sturgeon larvae. Safe concentrations of F− for Chinese sturgeon larvae were calculated with 0.01 LC50 (6-days) and 1.32 mg L−1 with Cl− while Ca2+ decreased the toxicity of F−. F− ameliorated toxicity of Cu2+. F− concentrations varied between 0.27 and 0.85 mg L−1 in the Yangtze River Estuary from August 2007 to May 2008. We assume that at the present level F− in the Yangtze Estuary does not cause adverse effects to juvenile Chinese sturgeon.

This study tested the hypothesis that different starvation time for fish before blood sampling can influence the result of plasma biochemical analysis. Glucose (GLU), total cholesterol (CHOL), triglyceride (TGL) and total protein (TP) in the plasma of juvenile Amur sturgeon (Acipenser schrenckii) were measured after different starvation duration (0, 0.5, 1, 2 and 3 days). Starvation time had a significant influence on plasma GLU, CHOL, TGL and TP concentrations (P

The objective of this study to design a delivery system resistant to the gastrointestinal environment for oral vaccine against porcine rotavirus.Lactococcus lactisNZ9000 was transformed with segments ofvP4of the porcine rotavirus inserted into the pNZ8112 surface-expression vector, and a recombinantL. lactisexpressing VP4 protein was constructed. An approximately 27 kDa VP4 protein was confirmed by SDS-PAGE , Western blot and immunostaining analysis. BALB/c mice were immunized orally with VP4-expression recombinantL. lactisand cellular, mucosal and systemic humoral immune responses were examined. Specific anti-VP4 secretory IgA and IgG were found in feces, ophthalmic and vaginal washes and in serum. The induced antibodies demonstrated neutralizing effects on porcine rotavirus infection on MA104 cells. Our findings suggest that oral immunization with VP4-expressingL. lactisinduced both specific local and systemic humoral and cellular immune responses in mice.