Structure design and surface interference analysis of double crown surface configuration of multistage face gears

A novel transmission using the multistage face gears as the core component is used to realize variable speed with differential gear shifting, there are multiple face gears superimposed on the radial direction, meshing with planetary wheel at the same time, which achieves different outputs speed through braking different face gears. In order to solve the interference problems caused by asynchronous meshing motion between several face gears and the same cylinder gear, this study mainly focuses on the meshing theory study based on the double crown surfaces in tooth profile and tooth orientation. The surface structure of straight tooth and double crown are constructed according to the related surface equations, the corresponding interference conditions are obtained by comparison, every single stage face gear model is designed and assembled. This study shows that the double crown configuration surface structure can easily improve contact characteristics compared with straight tooth surface structure of face gear. In addition, the double crown configuration surface structure can improve the distribution and direction of contact path. This study is expected to establish a new tooth surface model, which can provide the best machining parameters for the face gears

Simulation Analysis on Quasistatic Characteristics of Multistage Face Gears with Double Crown Surface

The multistage face gears are the core component of the planetary gear train, which is symmetrically meshed by multiple single-stage face gear and multiple cylindrical gears. However, it is difficult to synchronize the contact between face gears and cylindrical gear due to the tooth number differences. Thus, the interference problems between two stages and big stress concentration are obvious. The crown surface configuration technology and structure design were introduced to optimize the meshing condition. To improve the double crown design feasibility and meshing stability, it is necessary to establish a reasonable multistage face gears pair simulation model to evaluate various influence factors on the contact condition and quasi-static characteristics of multistage face gears structure. The relevant scatter plots are fitted by comparing the contact results with different crown quantities and friction coefficients to intuitively obtain the variation regularity of maximum deformation, maximum strain, maximum stress and maximum strain energy. The natural frequency and mode coefficient are also determined by modal analysis under these two conditions. All the above mentioned studies verified the contact conjugate properties of double crown surface configuration were suitable. The results can provide a foundation for structure optimization and transmission reliability of multistage face gears

Improving the stability and transdermal permeability of phycocyanin loaded cubosomes

Instability and low transdermal permeability of protein antioxidants are major obstacles to resist oxidative stress in transdermal drug delivery system. To overcome these shortcomings, cubosomes were developed as an advanced transdermal delivery system to improve stability and transdermal absorption of the model antioxidant phycocyanin in this study. Glyceryl monooleate and poloxamer 407 (P407) were used to prepare cubosomes as carrier matrix and stabilizer, respectively. Phycocyanin loaded cubosomes (PC-cubosomes) were prepared by the emulsification and homogenization method. A 33 full factorial design was used to optimize the cubosome formulations. The final optimal PC-cubosomes possessed an average particle size of 183.2 ± 0.5 nm and a negative surface charge as well as achieved a high encapsulation efficiency of 87.2% ± 2.7%. PC-cubosomes appeared as nano-sized and well-shaped spheres with highly ordered cubical structures. The residual amount of phycocyanin in PC-cubosomes was 3-fold higher than that in the free drug solution after 10 days ultraviolet radiation exposure. In vitro release kinetics of phycocyanin from PC-cubosomes fitted to the Higuchi kinetic model, indicating that phycocyanin released from cubosomes mainly attributed to drug diffusion and dissolution. PC-cubosomes also exhibited higher permeability (39.79 μg⋅cm−2⋅hour−1) across the rat skin than phycocyanin solution (16.33 μg⋅cm−2⋅hour−1). Furthermore, PC-cubosomes were easily taken up by keratinocytes, thereby achieving a prolonged anti-oxidative stress effect. These results therefore suggested that cubosomes could be a promising transdermal delivery system to improve the stability and transdermal permeability of phycocyanin

Alginate oligosaccharides trigger multiple defense responses in tobacco and induce resistance to Phytophthora infestans

Alginate oligosaccharides (AOSs), important plant immunity inducers, are widely used in agriculture because of their important role in the biological control of crop diseases. However, the mechanism by which AOSs induce plant resistance to pathogens is not clear. Here, we report AOS with a degree of polymerization of 2–5, which was obtained by a newly reported enzyme Aly2. AOS treatment exhibited high activity in enhancing resistance to Phytophthora infestans (P. infestans). AOS significantly induced reactive oxygen species (ROS) accumulation, calcium influx, stomata closure, and callose deposition. The salicylic acid (SA) synthesis-related gene and the defense-related genes were upregulated after AOS treatment. A transcriptome file generated from AOS-treated seedlings verified the SA pathway and suggested the presence of chitin elicitor receptor kinase (CERK). The subsequent results showed that AtCERK1 binds AOS tightly, suggesting that AtCERK1 is responsible for AOS recognition. This study laid a theoretical foundation for the broad application of AOS

Studies on fatty acids and microbiota characterization of the gastrointestinal tract of Tianzhu white yaks

IntroductionThe gut microbiota significantly influences the host’s production performance and health status, with different gastrointestinal tissues exhibiting functional diversity reflected in their microbial diversity.MethodsIn this study, five adult male Tianzhu white yaks (4.5 years old) were selected and fed under the same nutritional conditions. After the feeding experiment, the yaks were slaughtered, and chyme samples were collected from the rumen, abomasum, jejunum, and colon for 16S rRNA full-length sequencing and volatile fatty acid analysis.ResultsThe results showed that the microbial composition and diversity of the rumen and abomasum were similar, with close genetic distances and functional projections. In contrast, the jejunum and colon had distinct microbial compositions and diversity compared to the rumen and abomasum. At the phylum level, the dominant phyla in the rumen, abomasum, and colon were Firmicutes and Bacteroidetes, while in the jejunum, the dominant phyla were Firmicutes and Proteobacteria. The abundance of Firmicutes differed significantly between the jejunum (87.24%) and the rumen (54.67%), abomasum (67.70%), and colon (65.77%). Similarly, Bacteroidetes showed significant differences between the jejunum (2.21%) and the rumen (36.54%), abomasum (23.81%), and colon (28.12%). At the genus level, Rikenellaceae_RC9_gut_group and Christensenellaceae_R-7_group were dominant in both the rumen and abomasum. In the jejunum, Romboutsia and Paeniclostridium were dominant, while Rikenellaceae_RC9_gut_group and UCG-005 were the dominant genera in the colon. At the species level, rumen_bacterium_g_Rikenellaceae_RC9_gut_group and rumen_bacterium_g_Christensenellaceae_R-7_group were dominant in both the rumen and abomasum, while Clostridium_sp._g_Romboutsia and bacterium_g_Paeniclostridium were unique to the jejunum. Ruminococcaceae_bacterium_g_UCG-005 and bacterium_g_Rikenellaceae_RC9_gut_group were unique to the colon. KEGG functional prediction of the microbiota indicated that the dominant functions in the rumen, abomasum, colon, and jejunum were amino acid metabolism, glycan biosynthesis and metabolism, carbohydrate metabolism, and membrane transport, respectively, reflecting the digestive functions of these organs. Volatile fatty acid analysis showed that the concentrations of acetic acid, propionic acid, and butyric acid in the rumen were significantly higher than those in the abomasum, jejunum, and colon (p < 0.05). Among these, the propionic acid concentration in the jejunum was significantly lower than in the abomasum and colon. Additionally, correlation analysis results indicated that acetic acid and butyric acid were significantly positively correlated with the ruminal bacterial community (p < 0.05). The total volatile fatty acid concentration was highest in the rumen, decreased to less than one-fifth of the rumen’s total volatile fatty acid concentration in the abomasum and jejunum, and then reached a second peak in the colon.ConclusionThis study explored the microbial composition and differential bacterial genera in the rumen and intestines of Tianzhu white yak, comparing the differences in volatile fatty acid levels and microbial composition and function across different regions. This is important for understanding their gastrointestinal microbiota’s spatial heterogeneity

Effects of Panax notoginseng saponins on proliferation and differentiation of rat embryonic cortical neural stem cells

AbstractBackgroundWe aimed to study the effect of Panax notoginseng saponins (PNS) on the proliferation, differentiation, self-renewal, and expressions of basic fibroblast growth factor (bFGF) and brain-derived neurotrophic factor (BDNF) in rat embryonic neural stem cells (NSCs).MethodsCortical stem cells were isolated from rat embryos on Embryonic Day 17 (E17) and identified by nestin expression. Subsequently, primary culture, subculturing, and single cell cloning were performed on the cells. After the first cell passage (P1), the cells were resuspended and divided into a control group and a treatment group. Control cells were cultured in serum-free basal culture medium with B27 and dulbecco's modified eagle medium (DMEM)/F12. The same medium supplemented with PNS (100 μg/mL) was used to culture cells in the treatment group. Both groups were incubated at 37°C in a 5% CO2 incubator. Immunocytochemistry was performed 4 days after incubation.ResultsPrimary, P1, and P2 cells in the treatment group formed neurospheres, as did single cell clones of the P1 cells in this group. After being cultured for 4 days, the number of nestin-, proliferating cell nuclear antigen (PCNA)-, Tuj-1-, neurofilament (NF)-, vimentin-, glial fibrillary acidic protein (GFAP)-, bFGF-, and BDNF-positive cells significantly increased in the treatment group in comparison to the control group. All positively stained cells could form clear clusters.ConclusionPNS can promote rat embryonic cortical NSC survival, self-renewal, proliferation, and differentiation through neurotrophic factors by autocrine or paracrine signaling

Numerical modeling and dynamic characteristics study of coupling vibration of multistage face gearsplanetary transmission

Abstract. A novel transmission with multistage face gears as the core component achieves variable speeds via differential gear shifting. Single/multistage coupled vibration models have been established in this study to derive the coupled vibration equation in order to accurately solve the load distribution between the meshing teeth and the vibration shock between the shifting stages in the transmission process, improve the transmission smoothness of the face gears during the shifting processing, suppress the resonance of face gears meshing, reduce the noise, and optimize the power transmission performance. The characterization relationships of the key parameters such as equivalent mass, rotational inertia, equivalent mesh stiffness, support stiffness, and meshing damping coefficient to dynamic characteristics were investigated. The linear and nonlinear dynamic characteristics of coupled vibration differential equations were solved. The influence rules of factors such as integrated transmission error, dynamic load, tooth surface friction, loading speed, and load on the transmission system were analyzed. The results of the study provide a theoretical basis for the expansion of field of application of transmission devices. </jats:p

Study on kinematic characteristics of planetary multistage face gears transmission

A planetary gear transmission system with multistage face gears combinations as core component can easily realize the variable speed in differential transmission ratios with structural advantages. In order to improve the transmission stability and loading capacity, it is necessary to set up a reasonable kinematic model for multistage face gears pair. This study focuses on the kinematic characteristics of multistage face gears structure with double crown surface by the methods of numerical calculation and experimental verification. The transmission error and efficiency solving models are established by numerical calculation method to analyze the influences of each factor in detail. Then the correctness of the above numerical models are verified with transmission error and efficiency experiment. In addition, the numerical results are compared with the experimental results to further indicate the important influences of the multistage face gears components on the transmission error and efficiency of whole transmission system. The results can provide references for the dynamic and experimental study of multistage face gears in some degree. </jats:p

PLGA microsphere-based composite hydrogel for dual delivery of ciprofloxacin and ginsenoside Rh2 to treat Staphylococcus aureus-induced skin infections

When antibiotic-resistant pathogenic bacteria pose a high threat to human health, bacterial multidrug efflux pumps become major contributors to the high-level antibiotic resistance in most microorganisms. Since traditional antibiotics are still indispensable currently, we report a dual drug delivery system to maximize the antibacterial efficacy of antibiotics by inhibiting efflux pumps in bacteria before their exposure to antibiotics. In this research, a microsphere/hydrogel composite was constructed from ciprofloxacin (Cip)-loaded poly (lactic-co-glycolic acid) (PLGA) microspheres and ginsenoside Rh2 (G-Rh2) dispersed thermo-sensitive hydrogel to treat skin infections. In vitro drug release studies indicated that while G-Rh2 in hydrogel presented a faster and short-term release manner to rapidly inhibit the NorA efflux pumps, Cip showed a sustained and long-term release behavior to provide a local high concentration gradient for facilitating drug percutaneous penetration. The combination of Cip and G-Rh2 demonstrated a high degree of synergism against both methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA), hence significantly improving their in vitro antibacterial activity and efficiency. Moreover, the antibacterial performance of the microsphere/hydrogel composite with a sequential release profile is superior to that of other formulations in mouse model of MRSA skin infections, indicating its great potential to treat antibiotic-resistant skin infections