Osteoporosis deteriorates bone mass and biomechanical strength, becoming a life-threatening cause to the elderly. MicroRNA is known to regulate tissue remodeling; however, its role in the development of osteoporosis remains elusive. In this study, we uncovered that silencing miR-29a expression decreased mineralized matrix production in osteogenic cells, whereas osteoclast differentiation and pit formation were upregulated in bone marrow macrophages as co-incubated with the osteogenic cells in transwell plates. In vivo, decreased miR-29a expression occurred in ovariectomy-mediated osteoporotic skeletons. Mice overexpressing miR-29a in osteoblasts driven by osteocalcin promoter (miR-29aTg/OCN) displayed higher bone mineral density, trabecular volume and mineral acquisition than wild-type mice. The estrogen deficiency-induced loss of bone mass, trabecular morphometry, mechanical properties, mineral accretion and osteogenesis of bone marrow mesenchymal cells were compromised in miR-29aTg/OCN mice. miR-29a overexpression also attenuated the estrogen loss-mediated excessive osteoclast surface histopathology, osteoclast formation of bone marrow macrophages, receptor activator nuclear factor-κ ligand (RANKL) and C–X–C motif chemokine ligand 12 (CXCL12) expression. Treatment with miR-29a precursor improved the ovariectomy-mediated skeletal deterioration and biomechanical property loss. Mechanistically, miR-29a inhibited RANKL secretion in osteoblasts through binding to 3′-UTR of RANKL. It also suppressed the histone acetyltransferase PCAF-mediated acetylation of lysine 27 in histone 3 (H3K27ac) and decreased the H3K27ac enrichment in CXCL12 promoters. Taken together, miR-29a signaling in osteogenic cells protects bone tissue from osteoporosis through repressing osteoclast regulators RANKL and CXCL12 to reduce osteoclastogenic differentiation. Arrays of analyses shed new light on the miR-29a regulation of crosstalk between osteogenic and osteoclastogenic cells. We also highlight that increasing miR-29a function in osteoblasts is beneficial for bone anabolism to fend off estrogen deficiency-induced excessive osteoclastic resorption and osteoporosis.

The vibration of an annular plate that is free along its outer edge, and that is connected to a flange along its inner edge by bolts that are equally spaced in the circumferential direction, is studied. A disk with this geometry, or a stacked array of such disks, is common in applications involving data storage, rotating machinery, or brake systems. The periodic structural imperfections that are associated with the bolt pattern can have interesting implications for the plate’s dynamic response. Changes that occur in the natural frequencies and mode shapes as a result of such deviations from an ideally clamped inner edge are studied through laboratory measurements, and through an approximate model that captures the rotationally periodic character of the bolted plate and flange system. In the axisymmetric case, the natural frequencies of the plate’s “sine” and “cosine” vibration modes are repeated for a specified number of nodal diameters. Under the influence of a regular bolt pattern, and the resulting local variations of the stiffness and compression at the plate/flange interface, some natural frequencies are repeated and others split. This process depends on the number of bolts used to mount the plate, and on the number of nodal diameters present in a specific vibration mode. A straightforward criterion to predict the split and repeated modes is discussed.

Viscoelastic damping isolator (VDI) is a new way to reduce the vibration of punch press in automobiles, motorcycles, IT, aerospace, mold and other industries. It not only reduces the vibration of large punching machine and equipment, but also decreases its maintenance costs and avoids endangering the surrounding environment. VDI is composed of partitions, damping fluid, steel springs and level adjusters. Different number of the partitions are welded on upper and lower rectangular steel plates, respectively. Steel springs are placed at the edges between the plates to support up to 150 tons of weight of the punch press. Screw level adjusters are place between lower and thick bottom plates to adjust the horizontal level of the isolator. The damping fluid is filled in the space between interlacing partitions approximate 60% of the height of the composed isolator. The impact energy produced by the presser is dissipated by shear deformation between the damping fluid and partitions. This article used 3D graphing software and finite element method (FEM) to investigate the dynamic characteristic of the damping isolator after impacted by the puncher. The normal mode analysis of the VDI is obtained. The isolator is settled within 0.3 seconds after 300,000 N shock impact and satisfies industrial specification of large punchers with loading frequency of 100 cycle/min.

Sun intensity and angle on efficiency of solar cell System is considered to study. Solar energy is a clean, non-polluting and renewable resource; it uses the photovoltaic effect to convert sunlight into a free and available energy source. However, solar energy output is highly affected by the temperature and intensity of sunlight. As the temperature of the solar module rises, energy output will decrease, if the intensity of sunlight is stronger, there will be more output energy. With adequate heat sink and proper ventilation, a module’s temperature will be decreased, and also increase output energy. This study uses 10 kilowatt grid-connected photovoltaic system and a solar tracker to measure the direction of the sun, to find out the relationship between solar intensity and angle effects on energy output.

Finite element analysis on natural properties of a micro drill with ultrasonic vibration is considered to study. Because getting smaller aperture in the printed circuit board (PCB), it tends to be more severe due to vibration. The vibration has adverse effects to machining accuracy and surface roughness which will increase tool abrasion and further accelerate the destruction from material fatigue. There are many ways to produce perforations, such as laser micro-machining and micro-drilling. The industry still adopts micro drill piercing process due to the cost and technical considerations. In order to enhance the cutlery life and the quality of the drilling process, the cutting characteristic of bur is important. Hence, the vibration during drilling must be suppressed. This study is to investigate the natural properties of a micro drill under ultrasonic vibration (50 kHz) excited with a piezoelectric-driven actuator and numerically by using finite element analysis.

This paper investigates the vibration of an annular disk that is subjected to rotation and in-plane frictional traction distributed over a sector of the disk’s two faces. Technical applications include noise, vibration, and harshness in automotive and aircraft disk brakes, clutches, transmissions, and other rotating machine components. To the degree that the rotor-to-stator friction in such cases is directed along the disk’s deformable surface, it is treated here as a nonconservative follower-type load. The vibration model incorporates membrane stiffness which derives both from rotation, and from the stresses established as a result of friction. The plane stress state is determined in closed form as a Fourier series, and that solution is compared with the companion, but computationally intensive, results from finite element analysis. For the cases of sector-shaped and full annular loading, the vibration model predicts the critical mode, which is defined as the one that becomes dynamically unstable at the lowest friction level. Vibration modes and propagating waves that fall into opposite symmetry classes are shown to have opposite stability characteristics in the presence of frictional loading.

Vibration of an array of stacked annular plates, in which adjacent plates couple weakly through an acoustic layer, is investigated through experimental and theoretical methods. Such acoustic coupling manifests itself through split natural frequencies, beating in the time responses of adjacent or separated plates, and system-level modes in which plates in the array vibrate in- or out-of-phase at closely-spaced frequencies. Laboratory measurements, including a technique in which the frequency response function of all in-phase modes but no out-of-phase modes, or visa versa, is measured, demonstrate the contribution of coupling to the natural frequency spectrum, and identify the combinations of design parameters for which it is important. For the lower modes of primary interest here, the natural frequencies of the out-of-phase system modes decrease as the air layer becomes thinner, while those of the in-phase mode remain sensibly constant at the in vacuo values. A vibration model comprising N classical thin plates that couple through the three-dimensional acoustic fields established in the annular cavities between plates is developed, and its results are compared with measurements of the natural frequencies and mode shapes.

Material characteristics, such as electric potential, distance between target material and substrate, and so on, are important parameters for vacuum metal films deposition (sputtering) system. Properly controlling these parameters during the sputtering process can reduce the residual stress after deposition and can effectively improve the deformation of substrate and density of metal thin film. This study aims at simulating a vacuum metal film deposition system for substrate application with normal metal material. Both the copper foil, as a target material, and the substrate that is placed on a carrier platform are included in a vacuum chamber. The argon ion gas is excited by a radio frequency power generator to form the plasma source in the sputtering system. ''Glow Discharge'' of the ''Paschen Curve'' during plasma generation process is employed to excite the argon ion gas to bombard the target material. The ejected atoms of target material are deposited on the substrate surface to form the desired thin films. Several different parameters, such as radio frequency power, electric field intensity, distance between the target materials and the substrate, and so on, are discussed in this article. Numerical analysis results indicate that the distance between the substrate and target materials may affect the density of metal film significantly. The MATLAB simulation results can provide the technique of finding better workpiece height and high coating quality for the semi-conduction industrial adopting sputtering system for metal thin film production.