Gut microbial induction of host immune maturation exemplifies host-microbe mutualism. We colonized germ-free (GF) mice with mouse microbiota (MMb) or human microbiota (HMb) to determine whether small intestinal immune maturation depends on a coevolved host-specific microbiota. Gut bacterial numbers and phylum abundance were similar in MMb and HMb mice, but bacterial species differed, especially the Firmicutes. HMb mouse intestines had low levels of CD4(+) and CD8(+) T cells, few proliferating T cells, few dendritic cells, and low antimicrobial peptide expression--all characteristics of GF mice. Rat microbiota also failed to fully expand intestinal T cell numbers in mice. Colonizing GF or HMb mice with mouse-segmented filamentous bacteria (SFB) partially restored T cell numbers, suggesting that SFB and other MMb organisms are required for full immune maturation in mice. Importantly, MMb conferred better protection against Salmonella infection than HMb. A host-specific microbiota appears to be critical for a healthy immune system.

Gut Immune Maturation Depends Upon Colonization with Host-Specific Microbiota

A 10-week feeding trial was conducted to investigate the effects of dietary bile acids (BA) on growth, glucose and lipid metabolism, liver histopathology, and the underlying regulation mechanism on AKT/FOXO1 (forkhead box O1) and cAMP/AMPK/SREBP1 (sterol regulatory element-binding protein 1) pathway in largemouth bass (Micropterus salmoides) fed with a high starch diet. Six experimental diets were prepared with BA levels at 0 (B0), 80 (B80), 160 (B160), 240 (B240), 300 (B300), and 600 (B600) mg/kg in a basal diet with 18.7% starch. Each diet was fed to six replicates with 30 fish (6.17 ± 0.03 g) in each tank. The highest weight gain rate (WGR) was observed in B300 group and the optimal level of BA was estimated at 475 mg/kg by a monistic cubic equation regression analysis. Dietary BA inclusion decreased hepatosomatic index (HSI) and hepatic lipid content significantly. The fish in B300 group clearly showed alleviated hepatic fibrosis, but more steatohepatitis symptoms diagnosed with various histopathological and immunofluorescence analysis. 10 out of 12 samples were observed hepatic fibrosis in B0 group while only two fibrosis samples in B300 group. The promoted liver histopathology by dietary BA was related to improved glucose and lipid metabolism. Dietary BA inhibited the expression of G6Pase by activating AKT and reducing FOXO1 transcription, which improved the regulation ability of gluconeogenesis, activated cAMP/AMPK and repressed SREBP1 transcription to inhibit hepatic lipogenesis, which prevented hepatic lipid accumulation. In conclusion, dietary BA enhanced the growth and alleviated liver fibrosis induced by a high starch diet to steatohepatitis/recovery symptom via improving glucose and lipid metabolism, which regulated by AKT/FOXO1 and cAMP/AMPK/SREBP1 pathway in largemouth bass.

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Dietary Bile Acids Enhance Growth, and Alleviate Hepatic Fibrosis Induced by a High Starch Diet via AKT/FOXO1 and cAMP/AMPK/SREBP1 Pathway in Micropterus salmoides

The non-Newtonian fluid polishing is an advanced method that is applied to machining the complex surfaces. This method significantly improves the surface quality and mechanical properties of the material. In addition, it also reduces the concentrated stress at the root of the gear, so the fatigue resistance of the material is increased. The characteristics of shear thickening fluid are applied to machining the alloy steel SCM435 gears in this study. Firstly, the relationships between main machining parameters (distance D, velocity V, and inclination angle I) and responses (pressure and surface roughness of gear) is investigated in the polishing process. The effect of three machining parameters to the polishing process is carried out by conducting the simulation and experiment. The simulations results found that the pressure area is distributed throughout all the gear surfaces and maximum pressure value is achieved about 16.3 kPa with inclination angle of 26 degrees. In addition, experimental results indicated that the surface roughness of the gear surfaces can be reach 12 nm after 25 min polishing. Finally, the multi-responses optimization is utilized to optimize the pressures on the gear surfaces in machining process. The experimental results illustrated that the surface roughness is achieved the smallest at maximum pressure area. The best surface roughness of the gear surfaces can be reach 13 nm under optimal machining parameters such as the distance of 15 mm, velocity of 1.5 m/s and inclination angle of 32 degrees.

Machining parameter optimization in shear thickening polishing of gear surfaces

Linkage model and manufacturing process of shaping non-circular gears

As the current research of face gear drive cannot realize fluctuating gear ratio, a design method of orthogonal fluctuating gear ratio face gear drive is proposed. The mathematical model of orthogo...

Geometry design, three-dimensional modeling and kinematic analysis of orthogonal fluctuating gear ratio face gear drive

Dietary supplementation of Grobiotic®-A increases short-term inflammatory responses and improves long-term growth performance and liver health in largemouth bass (Micropterus salmoides)

A simple and accurate numerical method was proposed for calculating the tooth profile of a noncircular gear. This method is directly based on the real gear shaping process, rather than deducing and solving complicated meshing equations used in the traditional method. The tooth profile is gradually obtained from the boundary produced by continuously plotting the cutter profile on the gear transverse plane. The key point of the method is picking up the graph boundaries. The relative position of the cutter profile on the gear transverse plane is determined by the given pitch line of the noncircular gear, parameters of the shaper cutter, and the shaping process data. In comparison with the traditional method, it is universal and is much more efficient and accurate, especially for noncircular gears, which have nontrivial pitch lines. Special problems in gear design and manufacturing, such as tooth pointing, undercut, and fillet interference, are included in the process. As an application example of the numerical method, a square internal gear is chosen from a new type of hydraulic motor with noncircular planetary gears, and the tooth profile of that gear is computed. The gear is successfully machined by electromagnetic discharge (EMD) using the resulting data.

Numerical computing method of noncircular gear tooth profiles generated by shaper cutters

The invention discloses a bevel gear machining method. According to the geometric parameters and the required tooth system of a gear to be machined, the method comprises the following steps that: (1) the parameters of a shaping gear wheel are determined; (2) the tooth traces of the shaping gear wheel are determined; (3) the parameters of a cutter are determined; (4) the cutter movement on the tooth surface of the shaping gear wheel is determined; (5) the basic tooth surface modification of the shaping gear wheel is determined; (6) the movement of the shaping gear wheel generating the gear is determined; (7) the movement of the gear generated by the shaping gear wheel is corrected; and (8) the generation of the gear to be machined is completed. The invention has the advantages that: (1) the cutting and the grinding of bevel gears with straight teeth, curved teeth, cycloidal teeth, quasi-involute teeth and the like can be implemented on one machine tool; (2) the dimension of the cutter is determined only by the module of the gear to be machined and has nothing to do with the diameter of the gear to be machined and the tooth width; (3) the diameter of the cutter or the grinding wheel is small, the torque of the machine tool spindle is small, the force applied to the machine tool is small, the deformation of the machine tool is small and the machining accuracy is high; (4) the position, the dimension and the shape of the contact spots on the tooth surface can be conveniently controlled and all kinds of theoretically full-conjugated bevel gear pairs can be machined; and (5) the transmission ratio function required by the gear pairs to be machined can be accurately realized.

Bevel gear machining method

The grinding of elliptical gears on a computer numerical control (CNC) gear grinder with conical wheel is studied according to the mesh theory of elliptical gears. Two machining methods form the machine structure and movement, namely a mobile grinding wheel type and a fixed grinding wheel type. Mathematical models of the movement relation for the elliptical gear grinding process are built up. Since the teeth of the elliptical gears are different from each other, their generating length is also different. Based on the analysis of generating and indexing movement, a universal generating length formula of each tooth is proposed. Basic machining parameters of each tooth, for these two types of machines, are computed using a practical example. The dynamic simulation of generating track is given. The research results show that the grinding of elliptical gears with a CNC conical wheel gear grinder is feasible.

Xutang Wu

Papers

Dietary supplementation of Grobiotic®-A increases short-term inflammatory responses and improves long-term growth performance and liver health in largemouth bass (Micropterus salmoides)

Numerical computing method of noncircular gear tooth profiles generated by shaper cutters

Bevel gear machining method

Investigation on the grinding of elliptical gears with CNC conical wheel gear grinder