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The light-weight and high-stiffness metal lattice sandwich structure formed by selective laser melting has an important application prospect in aerospace, military and other fields. In this study, the response of square lattice sandwich panels with different core spacings under three-point bending was analyzed by finite element analysis, and the results were verified by experimental samples formed by selective laser melting. The results show that there is a linear relationship between the core spacing and cylindrical bending stiffness when the core spacing is within a certain range, the influence of core spacing on cylindrical bending stiffness is very significant and the influence of core spacing on the cylindrical bending stiffness of the square lattice sandwich panel of 45° is greater than that of the square lattice sandwich panel of 0°. The cylindrical bending stiffness of square lattice sandwich panel of 0° and 45° is basically the same under the same relative density when the relative density is within a certain range, which means that they have similar cylindrical bending stiffness under the same weight. When the relative density is less than 5%, the relative density has a significant influence on the cylindrical bending stiffness, and the influence decreases when the relative density exceeds 5%. With the increase of the core spacing, the stress concentration area is transferred from the part of panel under the loading pad to the ends of cores between the support pads due to the reduction of the cylindrical bending resistance of the lattice structure. According to the mechanical analysis, the initial load prediction formula for the yield and plastic stages can be proposed, The comparison between the theoretical results and the FEA results shows that the relative error is less than 13.6%, indicating that the formula is relatively accurate. The experimental results are in good agreement with the FEA results, especially for the cylindrical bending stiffness, the relative error between the FEA value and the experimental value is only less than 6.5%, indicating that the three-point bending deformation and mechanical properties of the lattice sandwich panel can be effectively predicted by FEA.

Pig welfare is closely related to the economical production of pig farms. With regard to pig welfare assessment, pig sounds are significant indicators, which can reflect the quality of the barn environment, the physical condition and the health of pigs. Therefore, pig sound analysis is of high priority and necessary. In this review, the relationship between pig sound and welfare was analyzed. Three kinds of pig sounds are closely related to pig welfare, including coughs, screams, and grunts. Subsequently, both wearable and non-contact sensors were briefly described in two aspects of advantages and disadvantages. Based on the advantages and feasibility of microphone sensors in contactless way, the existing techniques for processing pig sounds were elaborated and evaluated for further in-depth research from three aspects: sound recording and labeling, feature extraction, and sound classification. Finally, the challenges and opportunities of pig sound research were discussed for the ultimate purpose of precision livestock farming (PLF) in four ways: concerning sound monitoring technologies, individual pig welfare monitoring, commercial applications and pig farmers. In summary, it was found that most of the current researches on pig sound recognition tasks focused on the selection of classifiers and algorithm improvement, while fewer research was conducted on sound labeling and feature extraction. Meanwhile, pig sound recognition faces some challenging problems, involving the difficulty in obtaining the audio data from different pig growth stages and verifying the developed algorithms in a variety of pig farms. Overall, it is suggested that technologies involved in the automatic identification process should be explored in depth. In the future, strengthen cooperation among cross-disciplinary experts to promote the development and application of PLF is also nessary.

To prepare excellent radiation protection material, bismuth tungstate nanocrystals were synthesized by hydrothermal method, and polyurethane based bismuth tungstate composites were prepared. The effects of crystal structure and morphology on the gamma ray shielding properties of bismuth tungstate were studied. The results indicated that the pH value of precursor solution had a large effect on the synthesis of bismuth tungstate, orthorhombic Bi2WO6 were obtained under acidic and neutral conditions, and tetragonal Bi0.875W0.125O1.6875 were obtained under strong alkali condition. With the increase of pH value, the morphology of bismuth tungstate changed from flower like microspheres to persimmon like microstructures, and then to randomly stacked nanosheets. It was found that orthorhombic persimmon-like Bi2WO6 showed higher shielding properties to 81 keV gamma rays, whereas tetragonal Bi0.875W0.125O1.6875 showed higher shielding properties to 59.5 and 121.8 keV gamma rays, obvious differences were observed between the mechanical properties of the composites prepared by different crystalline bismuth tungstate. The results of this study provide a reference for the development of new radiation shielding materials with non-toxic, light weight and high efficiency.

With the V-shaped support continuous rigid frame bridge as the engineering background, the 0# block with V-shaped support was used for the construction stage analysis and construction working condition analysis. According to the analysis results, the following conclusions can be drawn: The stress of the 0# block with V-shaped support met the specification requirements during the construction process, and the stress characteristics during the construction process can be used for reference by designers and constructors. The 0# block with V-shaped support was more sensitive to horizontal displacement along the bridge and vertical displacement, and structural displacement monitoring should be paid attention to during the construction process. There is a certain gap between the analysis results of the construction working condition analysis and the more real analysis results of the construction stage, and the construction stage analysis is used as much as possible in the calculation and analysis of the actual project. [ABSTRACT FROM AUTHOR]

As a common structural element of directly buried heating pipeline, small angular deviations may easily fail within the city heating network. To study the law of strength by the non-linear finite element method (FEM), a numerical model under external load was developed, whereas the soil and pipe were simulated by solid elements and the interaction between pipeline and soil was simulated by contact elements. Changes and laws in peak Mises stress of the pipeline were determined through the calculation and comparison of stress under different characteristics like pipe diameter, wall thickness, angular radius etc. Case study showed that pipe-soil interaction model can accurately simulate the damage of pipeline as compared with experiment and the beam-soil spring model. To expand the applications of small angular deviations in heating engineering, it is possible to protect small angular deviations by increasing wall thickness, degree of compaction, limiting the radius, and improving the proportion of backfill. [ABSTRACT FROM AUTHOR]

The stability and mean extinction time for a metapopulation system driven by cross-correlated noises are investigated based on the Levins model. The stationary probability distribution is derived according to the Fokker-Planck equation. By virtue of the steepest decent method, the explicit expression of the mean extinction time is obtained. The numerical results show that additive white noise intensity Q weaken the stability of metapopulation, meaning that the internal noises have negative effect on the metapopulation. Also the multiplicative colored noise intensity D weaken the stability of metapopulation, meaning that the fluctuation of the external noises is harmful to the metapopulation. On the contrary, the stability of metapopulation is strengthed as the self correlation time of the multiplicative colored noiseτ increasing. Furthermore, the mean extinction time T(xs → x0) is a decreasing function of D when λ < 0, while a non-monotonic function of D when λ > 0, and there exists a maximal value as D varies. Meantime, T(xs → x0) is a increasing function of τ. [ABSTRACT FROM AUTHOR]

In recent years, China has made great progress in basic nanomedicine, nanotoxicology and nanobiology research. Nanotechnology has been continuously applied in biomaterial and medical device, more and more medical devices applying nanomaterials are developed and manufactured. In order to gain more comprehension and accurate understanding of the research and industrial development in nanobiomaterial medical devices, this study reviewed the common nanomaterial in medical devices and the regulatory situation of nanomaterial medical devices at home and abroad, and discussed the current challenges in biological evaluation of nanomaterial medical devices, with a view to providing ideas for the safety evaluation and research of related products.

In this study, cytometric beads array(CBA) was used to determine the immunoglobulin content in humoral immunity evaluation of biomedical materials. The bovine-derived acellular dermal matrix was selected as a test sample and implanted into Balb/C mice subcutaneously to 4 weeks according to the high, medium and low dose groups. Four weeks later, IgG1, IgG2a, IgG2b, IgG3, IgA, and IgM were measured by CBA. The data of the test group and the control group were analyzed statistically. The results showed that compared with the negative control group, there was no significant difference in the IgG3, IgA content in the positive control group, while the IgG1, IgG2a, IgG2b, and IgM contents were significantly higher than the negative control group; no significant differences were seen in the sample groups. The results show that the method is suitable for analysis of immunoglobulin content in humoral immunity evaluation of biomedical materials.

Objective To study the therapeutic effect of rapamycin (RAPA) on experimental autoimmune myasthenia gravis (EAMG) rats and to explore the related immune mechanisms. Methods The mouse-derived acetylcholine receptor alpha subunit 97-116 peptide (R97-116) was used to immunize Lewis rats to establish an EAMG rat model. The rats were randomly divided into three groups: complete Freund's adjuvant control group (CFA group), EAMG model control group, and RAPA treatment group [1 mg/(kg.d)]. The Lennon muscle strength scoring scale was used to evaluate rats' clinical symptoms in each group once every two days, and their body mass was recorded. ELISA was performed to detect the level of anti-R97-116 antibodies in the peripheral blood of rats. Flow cytometry was used to detect the numbers of Th17 cells and regulatory T cells (Tregs) in rat splenocytes. Splenocytes were stimulated with 5 μg/mL concanavalin A (ConA), 10 μg/mL R97-116 and RPMI1640 medium, and the proliferation activity of rat splenocytes was tested by CCK-8 assay. Results RAPA treatment significantly improved the body mass and clinical scores in EAMG rats. Compared with the CFA group, the number of Th17 cells in the spleen of the EAMG group increased, and the number of Tregs decreased. Compared with the EAMG group, the number of Th17 cells in the spleen of RAPA-treated rats significantly dropped, the number of Tregs went up, and the level of anti-R97-116 antibodies in the serum went down. RAPA treatment inhibited the proliferation of lymphocytes induced by RPMI1640 medium, R97-116, and ConA stimulation. Conclusion RAPA may alleviate the clinical symptoms of EAMG rats by down-regulating the ratio of Th17 cells/Tregs.

Objective: To investigate the effectiveness of extracorporeal shock wave therapy combined with platelet-rich plasma (PRP) injection in treatment of knee osteoarthritis (KOA) by prospective clinical study., Methods: Between June 2015 and June 2018, 180 patients with KOA met the inclusion criteria were included in study and randomly allocated to group A ( n =60), group B ( n =60), and group C ( n =60). The patients were treated with autologous PRP intra-articular injection in group A, extracorporeal shock wave therapy in group B, and extracorporeal shock wave therapy combined with autologous PRP intra-articular injection in group C, once a week and 5 times a duration of treatment. There was no significant difference in age, gender, disease duration, side of KOA, and Kellgren-Lawrence grading between groups ( P >0.05). The pain and function of knee joint were assessed by visual analogue scale (VAS) score, Lequesne Index score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, and knee joint activity before treatment and at 1, 3, and 5 weeks after the first treatment., Results: There were significant differences in VAS score, Lequesne Index score, WOMAC score, and knee joint activity between pre- and post-treatment in all groups ( P <0.05). VAS score, Lequesne Index score, and WOMAC score gradually decreased with the prolongation of treatment time ( P <0.05); but there was no significant difference in knee joint activity between different time points ( P >0.05). There was no significant difference in VAS score, Lequesne Index score, WOMAC score, and knee joint activity between groups before treatment ( P >0.05); the scores of group C were superior to groups A and B ( P < 0.05) at different time points after treatment; while the knee joint activities of 3 groups were similar ( P >0.05)., Conclusion: The extracorporeal shock wave therapy combined with PRP injection can relieve the pain synergistically for KOA.