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In order to reduce the leakage between the teeth of the twin-screw pump and improve the working performance, it is necessary to reduce the clearance between the teeth; In this paper, the end face profile equation of A-type screw rotor is derived by coordinate transformation method, the end face profile is generated based on MATLAB software, and the cusp and curve of the profile are optimized by arc transition method; The changes of pressure field and velocity field in the fluid domain of screw rotor before and after optimization are analyzed by finite element method; Taking the twin-screw pump as the research object, the fluid-structure coupling analysis and calculation of the master and slave screw rotors are carried out. The modal analysis of the screw without prestress and under the action of prestress is carried out respectively. Through the simulation calculation, the first six modal vibration shapes of the screw are taken, and the results of the two different states are compared. The results show that when the working pressure difference is 2 MPa, the maximum pressure after optimization increases by 1 % compared with that before optimization. With the continuous increase of center distance, the maximum pressure of flow field fluctuates slightly up and down; The maximum velocity after optimization is 3.5 % lower than that before optimization. The comparison results show that the frequency of the screw rotor increases with the increase of the modal order of the screw rotor without prestress. The frequencies of the second and third orders are similar, and the amplitudes of the first and fourth orders are similar. After the fluid-structure coupling force is applied, the change trends of the modal frequencies of each order are basically the same, but the magnitudes of the frequencies and amplitudes change. The amplitude of the main and driven screw rotors under the fluid-structure interaction decreases rapidly in the third-order vibration mode and is lower than the amplitude without prestress.

To study the influence of fissure angle on the failure mechanism of coal mass, uniaxial compression tests were conducted on coal specimens with different fissure angles. The failure process and acoustic emission characteristics during loading were obtained. The mechanical properties and failure mode were further analyzed. The results showed that (1) The stress-strain behavior of specimens with different fissure angles can be divided into four typical stages, compaction, elastic deformation, crack growth and propagation, and strain-softening. The existence of pre-existing fissures reduces the duration of the elastic stage with an obvious influence on the crack growth and propagation stage, and strain-softening stage. (2) The uniaxial compressive strength, elastic modulus of the specimens containing pre-existing fissure are all lower than those of the unfissured. The strength and elastic modulus do not change significantly with fissure angle, which is closely related to the primary fracture of the coal. (3) With the increase of the fissure angle, the crack initiation location moves from the center of the pre-existing fissure to the tip. While fissure angle has no obvious effect on the crack propagation direction, the cracks develop along the loading direction. (4) The AE characteristics can be divided into three typical periods, quiet period, active period, and remission period. With the increase of the fissure angle, the duration proportion of the quiet period increases, indicating that the energy storage time of coal increases. With the increase of the fissure angle, the occurrence time of low frequency and high energy signal is delayed, indicating that the large-size rupture gradually concentrates in the late loading period. (5) Compared with rock samples containing pre-existing fissure, coal specimens have more primary fractures, and the failure mechanism of coal is dominated by the non-uniform primary fractures.

The heterogeneous multilayer interface of VN/Ag coatings and transition multilayer interface of VN/Ag coatings were prepared on Inconel 781 and Si(100), and the microstructures, mechanical and tribological properties were investigated from 25 to 700 °C. The results showed that the surface roughness and average grain size of VN/Ag coatings with transition multilayer interface are obviously larger than those of VN/Ag coatings with heterogeneous multilayer interface. The coatings with transition multilayer interface have higher adhesion force and hardness than the coatings with heterogeneous multilayer interface, and both coatings can effectively restrict the initiation and propagation of microcracks. Both coatings have excellent self-adaptive lubricating properties with a decrease of friction coefficient as the temperature increases, but their wear rates reveal a drastic increase. The phase composition of the worn area of both coatings was investigated, which indicates that a smooth Ag, Magneli phase (V2O5) and bimetallic oxides (Ag3VO4 and AgVO3) can be responsible to the excellent lubricity of both coatings. To sum up, the coatings with transition multilayer interface have excellent adaptive lubricating properties and can properly control the diffusion rate and release rate of the lubricating phase, indicating that they have great potential in solving the problem of friction and wear of mechanical parts.

The lithology and thickness of the rock beam affect its mechanical properties and acoustic emission characteristics when it is fractured. In this study, three-point bending tests of rock beams were carried out. Then, we proposed to utilize the percentage of peak energy to characterize the intensity of energy release during fracture. Finally, the energy release mechanism of coal roof fracture was discussed. The evolution process of acoustic emission includes five stages. The acoustic emission amplitude distribution of rock beams has three typical patterns. Most of the cracks after fracture are tensile cracks, the proportion of tensile cracks is positively correlated with the elastic modulus. The percentage of peak energy is positively correlated with thickness and elastic modulus. More energy is released when thick and hard roof fractures. When necessary, measures such as reducing the thickness or the strength of the roof could be taken to improve the safety of mining.

In the internal thread extrusion forming, if the process parameters are not selected properly, the extrusion torque will increase, the extrusion temperature will be too high, or even the tap will break. In order to obtain effective process parameters under certain working conditions, this paper uses a combination of numerical simulation and process experiment to analyze the influence of the bottom hole diameter, extrusion speed, and friction factor on the extrusion torque and extrusion temperature. Through an orthogonal experiment, the significant influence law of different process parameters on the extrusion torque and extrusion temperature was studied, and the order of their influence was determined. Based on the optimal process parameters, numerical simulations and process tests were carried out, and the extrusion effect and related parameters were compared and analyzed. The results show that the extruded thread has clear contour, uniform tooth pitch, complete tooth shape, and good flatness. Compared with before optimization, the maximum extrusion torque has been reduced by 37.15%, the maximum temperature has been reduced by 29.72%, and the extrusion quality has been improved. It shows that the optimized method and optimized process parameters have good engineering practicability.

Background The efficacy of chemotherapeutic treatment of esophageal squamous cell carcinoma (ESCC) is limited by drug resistance during. This severely compromises the long-term survival rate of patients. Therefore, reversing chemotherapy resistance in ESCC may improve the therapeutic outcome. Here, we investigated the molecular mechanism of MUC1-C, the C-terminal transmembrane subunit of MUC1 (a transmembrane heterodimer protein), and its role in the reversal of cisplatin sensitivity in ESCC cells. Methods We assessed the efficacy of GO-203, a cell-penetrating peptide, as a chemotherapeutic target of MUC1-C using cell proliferation, colony-forming, and transwell assays. Apoptosis was analyzed in GO-203-treated cells by flow cytometry. Tumor xenograft assay was performed in nude mice to corroborate our in vitro findings. Results GO-203 treatment inhibited cell proliferation and restrained the migration and invasion of cisplatin-resistant ESCC. Moreover, targeting MUC1 resulted in enhanced apoptosis in GO-203-treated cells. These in vitro pro-apoptotic and anti-proliferative effects of GO-203 in combination with cisplatin were validated by in vivo models. Significantly smaller tumor volumes were observed in ESCCs-xenografted nude mice treated with GO-203 in combination with cisplatin compared with mice treated with monotherapy or their control counterparts. We found that blocking MUC1-C with GO-203 significantly reversed the cisplatin resistance in ESCC via modulating Akt and ERK pathways. Conclusions Our findings suggest that GO-203 may hold potential as an ancillary therapeutic molecule and a chemosensitizer to improve the outcomes of cisplatin-based chemotherapy especially in patients with cisplatin-resistant ESCC.

Severe deformation and instability problem of surrounding rock was caused by multiple severe mining dynamic load for roadway. Auxiliary haulage roadway 3101 for Menkeqing mine’s first working face was taken as engineering background in this paper. Field observation, borehole observation and numerical simulation were adopted to systemically analyze deformation and failure law of surrounding rock under double roadway driving and working face mining. The results were showed as follow: (1) When the roadway was subjected to the action of double roadway driving and working face mining, the deformation of surrounding rock began to increase sharply until 350 m behind the working face, characterized by serious subsidence in roof, heavy in floor and asymmetric destruction in two ribs. The deformation of the surrounding rock tended to be stable until 550 m in the rear of the working face; (2) Low strength and poor mechanical properties of surrounding rock, multiple mining and long-term effects of high stress are main reason of the overall instability of the roadway. (3) The key to control of the surrounding rock was to improve the integrity of the surrounding rock and to strengthen the key parts (coal pillar rib and roof) of roadway. The specific measures were as follows: improving the stability of coal pillar rib and roof, avoiding the transfer of high supporting stress to the floor, strengthening surface protecting of support structure, and improving the integrity of the roadway. According to the above research, a suitable strengthening control technology of surrounding rock which included “all cross-sectional bolt-wire mesh + high strength and lengthen bolt + high pre-tightening force cable” was put forward for field engineering practice. Through numerical simulation and engineering practice, the subsidence of the roof and the asymmetric deformation of two ribs could be effectively controlled, and ensured the stability of retained roadway in the process of mining.

The roof deformation and damage of roadway driving next to goaf in the vertical and horizontal directions are serious, the process of horizontal squeezing–expansion is difficult to be controlled using the traditional anchor truss structure. To solve this problem, a new type of cable-truss structure was designed to effectively control the deformation and damage of the roof along the vertical and horizontal directions. Besides, it had the function of horizontal bidirectional constant resistance. The mechanism of the structure is explained first. Then, the basic mechanical properties obtained through laboratory tests are presented. Finally, field practice is discussed. The results show that the new cable-truss structure has a load bearing force acting on its combination beam according to the horizontal movement of roadway roof. It can also adjust its length to prevent or adapt to the horizontal squeezing-expansion movement of roof, which ensures that the combination beam will not be distorted, torn, or broken. Thus, this new cable-truss structure can effectively mitigate the roof-caving accidents.

The co-reduction roasting and grinding magnetic separation‒of seaside titanomagnetite and blast furnace dust was investigated with and without fluorite addition at a reduction roasting temperature of 1250°C for 60 min, a grinding fineness of −43 μm accounting for 69.02wt% of the total, and a low-intensity magnetic field strength of 151 kA/m. The mineral composition, microstructure, and state of the roasted products were analyzed, and the concentrations of CO and CO2 were analyzed in the co-reduction roasting. Better results were achieved with a small fluorite dosage (≤4wt%) in the process of co-reduction. In addition, F− was found to reduce the melting point and viscosity of the slag phase because of the high content of aluminate and silicate minerals in the blast furnace dust. The low moisture content of the blast furnace dust and calcic minerals inhibited the hydrolysis of CaF2 and the loss of F−. Compared with the blast furnace dust from Chengdeng, the blast furnace dusts from Jiugang and Jinxin inhibited the diffusion of F− when used as reducing agents, leading to weaker effects of fluorite.

Spermiogenesis is a highly ordered and complex process in the male germ cell differentiation. The microtubule-based motor proteins KIF3A and KIF3B are required for the progression of the stages of spermiogenesis. In this study, the main goal was to determine whether KIF3A and KIF3B have a key role in spermiogenesis in Palaemon carincauda. The complete cDNA of KIF3A/3B from the testis of P. carincauda was cloned by using PCR and rapid amplification of cDNA ends (RACE). The predicted secondary and tertiary structures of KIF3A/3B contained three domains which were the: a) head region, b) stalk region, and c) tail region. Real-time quantitative PCR (qPCR) results revealed that KIF3A and KIF3B mRNAs were obtained for all the tissues examined, with the greatest gene expression in the testis. In situ hybridization indicated the KIF3A and KIF3B mRNAs were distributed in the periphery of the nuclear in the early spermatid of spermiogenesis. In the middle and late spermatid stages, KIF3A and KIF3B mRNAs were gradually upregulated and assembled to one side where acrosome biogenesis begins. In the mature sperm, KIF3A and KIF3B mRNAs were distributed in the acrosome cap and spike. Immunofluorescence studies indicated that KIF3A, tubulin, mitochondria, and Golgi were co-localized in different stages during spermiogenesis in P. carincauda. The temporal and spatial gene expression dynamics of KIF3A/3B indicate that KIF3A and KIF3B proteins may be involved in acrosome formation and nucleus shaping. Moreover, these proteins can transport the mitochondria and Golgi that facilitate acrosome formation in P. carincauda.

Spermatogenesis is a highly ordered process in the differentiation of male germ cells. Nuclear morphogenesis is one of the most fundamental cellular transformations to take place during spermatogenesis. These striking transformations from spermatogonia to spermatozoa are a result of phase-specific adaption of the cytoskeleton and its association with molecular motor proteins. KIFC1 is a C-terminal kinesin motor protein that plays an essential role in acrosome formation and nuclear reshaping during spermiogenesis in mammals. To explore its functions during the same process in Larimichthys crocea, we cloned and characterized the cDNA of a mammalian KIFC1 homolog (termed lc-KIFC1) from the total RNA of the testis. The 2481 bp complete lc-KIFC1 cDNA contained a 53 bp 5' untranslated region, a 535 bp 3' untranslated region, and a 1893 bp open reading frame that encoded a special protein of 630 amino acids. The predicted lc-KIFC1 protein possesses a divergent tail region, stalk region, and conserved carboxyl motor region. Protein alignment demonstrated that lc-KIFC1 had 73.2, 49.8, 49.3, 54.6, 56.5, 53.1, and 52.1% identity with its homologs in Danio rerio, Eriocheir sinensis, Octopus tankahkeei, Gallus gallus, Xenopus laevis, Mus musculus, and Homo sapiens, respectively. Tissue expression analysis revealed that lc-kifc1 mRNA was mainly expressed in the testis. The trend of lc-kifc1 mRNA expression at different growth stages of the testis showed that the expression increased first and then decreased, in the stage IV of testis, its expression quantity achieved the highest level. In situ hybridization and immunofluorescence results showed that KIFC1 was localized around the nucleus in early spermatids. As spermatid development progressed, the signals increased substantially. These signals peaked and were concentrated at one end of the nucleus when the spermatids began to undergo dramatic changes. In the mature sperm, the signal for KIFC1 gradually became weak and was mainly localized in the tail. In summary, evaluation of the expression pattern for lc-KIFC1 at specific stages of spermiogenesis has shed light on the potential functions of this motor protein in major cytological transformations. In addition, this study may provide a model for researching the molecular mechanisms involved in spermatogenesis in other teleost species, which will lead to a better understanding of the teleost fertilization process.

Amdoparvoviruses infect carnivore species, including mink, raccoon dog, fox, skunk, and red panda. Amdoparvovirus infection is a major cause of morbidity and mortality in farmed minks. Here, we developed a direct TaqMan qPCR assay for detection and quantification of carnivore amdoparvoviruses by using three primers and one probe based on the conserved VP2 gene. The detection limit for Aleutian mink disease virus (AMDV) and Raccoon dog and arctic fox amdoparvovirus (RFAV) were 4.06 × 101 copies/μl and 2.93 × 101 copies/μl, respectively. Both intra- and inter-assay variability were less than 2%. Among 74 carnivore samples, the positive rates for amdoparvoviruses were 62.2% (46/74) by direct TaqMan qPCR, while only 40.5% (30/74) by SYBR Green I qPCR. This result suggests that the direct TaqMan qPCR was more sensitive than the SYBR Green I qPCR. Additionally, the direct TaqMan qPCR is a rapid and sensitive method for liquid samples at microliter level as the assay employed the direct alkaline lysis method to obtain viral DNA and, therefore, eliminated the cumbersome steps in extracting DNA. Overall, the direct TaqMan qPCR assay possessed high specificity, sensitivity, and reproducibility, indicating that it can be used as a powerful tool for detection and quantification of various carnivore amdoparvoviruses in epidemiological and pathogenesis studies.

The present study aimed to investigate the effect of quercetin on cytotoxicity and cognitive degradation induced by amyloid β(Aβ)‑peptide in mice. Using the 1,1-diphenyl-2‑picrylhydrazyl (DPPH) method and a Y‑maze assay, the radical quenching ability and effect on working memory were determined, respectively, of quercetin treatment following 4 days of Aβ administration. The acute oral toxicity was assessed used to determine the concentration of quercetin at which 50% lethality of the neuronal cells was induced. For determination of the effect of quercetin on degradation of learning and memory loss induced by Aβ, a passive avoidance test was used. The results revealed that quercetin was involved in the inhibition of DPPH radical activity and was found to reduce radical activity by 76.5%. Quercetin significantly protected PC12 neuronal cells from death induced by Aβ treatment. Treatment of mice with daily doses of 100 mg/kg body weight quercetin for 30 days significantly improved the degradation of learning and memory loss induced by Aβ. The acute oral dose of quercetin in mice was determined to be 575 mg/kg body weight. Therefore, quercetin was found to be of therapeutic value for the treatment of neurological disorders, including AD, although further investigations are required.

Catalase (CAT) is an essential antioxidant in organisms, its can eliminate hydrogen peroxides produced in the cellular environment. Previous studies have focused mainly on the functions of CAT by pathogen challenge, but the functions of CAT by metals stress remain unclear. In order to investigate the function of CAT in Acrossocheilus fasciatus (AfCat), we cloned CAT complete cDNA sequences and analyzed its functions by cadmium (Cd) stress. qPCR analysis illustrated that the expression of CAT changed rapidly and dynamically in response to Cd from 0.05 mg L-1 to 1.25 mg L-1. Enzyme activity assay result showed that CAT activity was up-regulated significantly in response to Cd from 0.05 mg L-1 to 1.25 mg L-1. Histochemistry analysis showed that the structure of liver, testis and kidney were severely damaged by exposed to Cd of 1.25 mg L-1. Collectively, the results of our study indicate that AfCat may play an indispensable role in maintaining redox balance under Cd exposure, but AfCat expression will be inhibited when Cd accumulation reaches to the critical concentration. This study will illuminate the potential functions of AfCat in the defense mechanisms of reproductive and metabolic systems under Cd exposure in A. fasciatus.

Heat shock protein 70 (HSP70) is molecular chaperone that is important for reproductive biological processes. In this study, a full length HSP70 from the mudskipper (Boleophthalmus pectinirostris) was characterized. It was found to contain: a 108 bp 5'-untranslated region, a 208 bp 3'-untranslated region, and a 1953 bp open reading frame, which encodes a protein of 650 amino acids with a theoretical molecular weight of 71.1 kDa and an isoelectric point of 5.17. RT-PCR analysis revealed that HSP70 was ubiquitously expressed in all major tissues with differential expression levels. This suggests that HSP70 has vital and conserved biological functions. HSP70 was localized mainly in the cytoplasm of germinal cells, indicating an important role of this protein during spermatogenesis. In response to heat stress, the testes presented abnormal morphology in connective tissues, in which HSP70 immunoreactivity was not observed. HSP70 mRNA expression in the gill, liver, and testes was significantly increased, which suggests that HSP70 plays an important role in protection against heat stress.

Physicochemical Problems of Mineral Processing; ISSN 2084-4735