Planetary Gearbox Dynamic Modeling Considering Bearing Clearance and Sun Gear Tooth Crack.

Planetary gearbox systems are critical mechanical components in heavy machinery such as wind turbines. They may suffer from various failure modes, due to the harsh working environment. Dynamic modeling is a useful method to support early fault detection for enhancing reliability and reducing maintenance costs. However, reported studies have not considered the sun gear tooth crack and bearing clearance simultaneously to analyze their combined effect on vibration characteristics of planetary gearboxes. In this paper, a dynamic model is developed for planetary gearboxes considering the clearance of planet gear, sun gear, and carrier bearings, as well as sun gear tooth crack levels. Bearing forces are calculated considering bearing clearance, and the dynamic model equations are updated accordingly. The results reveal that the combination of bearing clearances can affect the vibration response with sun gear tooth crack by increasing the kurtosis. It is found that the effect of planet gear bearing clearance is very small, while the sun gear and carrier bearing clearance has clear impact on the vibration responses. These findings suggest that the incorporation of bearing clearance is important for planetary gearbox dynamic modeling.

Expression of a novel dual-functional polypeptide and its pharmacological action research.

AIMS: To develop a dual-functional medicine for hypoglycemic and anti-thrombus. MAIN METHODS: The long-acting glucagon like peptide-1 (5×GLP-1) and nattokinase (NK) were cloned by SOE PCR and gained the GLP-1 and NK fusion polypeptide after transformed into E. coli. Use of mice models for the hypoglycemic and anti-thrombus activity of the fusion polypeptide. Balb/C mice were given the carrageenan by intraperitoneal injection to induce tail thrombus models. Type 2 diabetes mellitus mice model was used to research the hypoglycemic function of the fusion polypeptide. KEY FINDINGS: Results showed that the fusion polypeptide could significantly prevent thrombus formation after oral administration. Continuous administration for 15 days, fasting blood glucose levels of the experimental group decreased to nearly normal levels. SIGNIFICANCE: The present study investigated the expression, purification and functional activity of the rolGLP-1 and NK fusion polypeptide, which provided a foundation for further studying the detailed pharmaceutical mechanism and drug development.

Construction of a Pichia pastoris strain efficiently secreting irisin and assessment of its bioactivity in HepG2 cells.

Irisin, a circulating myokine, has been shown to effectively ameliorate insulin resistance and type 2 diabetes mellitus by administration of the recombinant protein. Therefore, it is important to efficiently produce active irisin protein and further characterize its potential mechanism against hepatic insulin resistance. In this study, we obtained a multi-copy irisin-expressing P. pastoris strain through an optimized method, which is pH 5.5, 1.8% methanol for 96 h, for producing a high amount of recombinant irisin protein following a series of screening and optimization procedures. The higher-glycosylated irisin, which is supposed to be the active form was obtained by dialysis and ion-exchange chromatography purification method. Both of the laser scanning confocal microscope and the atomic force microscope not only detected the high-effectiveness entering cells of FITC-irisin but also localized it on the membrane of HepG2 cells. Immunofluorescence staining further suggested that irisin could localize in the cytoplasm but not in the nucleus. We further showed that glycosylated irisin rescued palmitate-induced reduction in Glut2 expression and cell viability, inhibited the apoptosis, potentially by activating PI3K/AKT pathway. In summary, we developed an efficient irisin-expressing P. pastoris strain and optimal expression condition, visualized its distribution, demonstrated biological activity and potential mechanisms in hepatic cells.

The extended Price equation quantifies species selection on mammalian body size across the Palaeocene/Eocene Thermal Maximum.

Species selection, covariation of species' traits with their net diversification rates, is an important component of macroevolution. Most studies have relied on indirect evidence for its operation and have not quantified its strength relative to other macroevolutionary forces. We use an extension of the Price equation to quantify the mechanisms of body size macroevolution in mammals from the latest Palaeocene and earliest Eocene of the Bighorn and Clarks Fork Basins of Wyoming. Dwarfing of mammalian taxa across the Palaeocene/Eocene Thermal Maximum (PETM), an intense, brief warming event that occurred at approximately 56 Ma, has been suggested to reflect anagenetic change and the immigration of small bodied-mammals, but might also be attributable to species selection. Using previously reconstructed ancestor-descendant relationships, we partitioned change in mean mammalian body size into three distinct mechanisms: species selection operating on resident mammals, anagenetic change within resident mammalian lineages and change due to immigrants. The remarkable decrease in mean body size across the warming event occurred through anagenetic change and immigration. Species selection also was strong across the PETM but, intriguingly, favoured larger-bodied species, implying some unknown mechanism(s) by which warming events affect macroevolution.