A computer-aided method for optimum design of plate cam-size avoiding undercutting and separation phenomena—II: Design nomogramsEine rechnergestützte methode zur konstruktion optimaler kurvengetriebe ohne unterschnitt und anheben der rolle. Teil 2: Konstruktionsnomogramme

This study presents design nomograms which make it easy for the cam designer to estimate the limiting value of the investigated parameter which can be applied to a plate cam follower system, as long as the maximum contact stress between the cam and follower during both rise and return strokes of cam revolution can be determined. The undesirable phenomena of the undercutting of cam profile and the separation between the cam and the follower are taken into consideration. Moreover, these design nomograms give correlations between the investigated parameters and the optimum plate cam size and also are used to study the influence of an investigated parameter on this size. The optimum plate cam size is the combination of cam base circle radius and the amount of cam follower offset, and satisfies the suggested design procedure which is based on taking the contact stress as a design criterion. The investigated parameters are dynamic, kinematic, geometric and material. A brief discussion on using the suggested design procedure to design the size of plate cam is described. For a numerical example, the presented design nomograms are for reciprocating cam-roller-follower which operated by parabolic plate cam.     

Evaluation and control of the adhesiveness of cohesive calcium carbonate particles at high temperatures

Understanding the adhesiveness of fine particulate materials at high temperatures is important to achieving the stable, economical operation of various industrial systems. In the present research, two types of calcium carbonate (CaCO₃) particles having different mean particle sizes (often used as heat carriers in energy systems) were evaluated. The tensile strengths of beds of these materials were determined at various temperatures by tensile strength measurement tester. The adhesiveness was found to increase greatly at 500 °C even without chemical reactions or sintering, and X-ray diffraction analyses showed thermal expansion of the CaCO₃ crystals at 500 °C. Pure alumina (Al₂O₃) and silica (SiO₂) microparticles did not exhibit the same pronounced increases in tensile strength or crystal expansion at this same temperature. Because the surface distances between these primary particles were presumably small, it is proposed that van der Waals forces between the particles greatly increased at high temperatures. The addition of Al₂O₃ nanoparticles to the CaCO₃ decreased the tensile strengths of the powder beds both at ambient temperature and at 500 °C. The experimental data confirm that the surface distances between primary particles were increased upon incorporating the nanoparticles, such that the tensile strength decreased during heat treatment.     

Experimental visualization of lithium diffusion in LixFePO4

Chemical energy storage using batteries will become increasingly important for future environmentally friendly ('green') societies. The lithium-ion battery is the most advanced energy storage system, but its application has been limited to portable electronics devices owing to cost and safety issues. State-of-the-art LiFePO4 technology as a new cathode material with surprisingly high charge-discharge rate capability has opened the door for large-scale application of lithium-ion batteries such as in plug-in hybrid vehicles. The scientific community has raised the important question of why a facile redox reaction is possible in the insulating material. Geometric information on lithium diffusion is essential to understand the facile electrode reaction of LixFePO4 (0相似文献   

Role of NADH shuttle system in glucose-induced activation of mitochondrial metabolism and insulin secretion

Glucose metabolism in glycolysis and in mitochondria is pivotal to glucose-induced insulin secretion from pancreatic beta cells. One or more factors derived from glycolysis other than pyruvate appear to be required for the generation of mitochondrial signals that lead to insulin secretion. The electrons of the glycolysis-derived reduced form of nicotinamide adenine dinucleotide (NADH) are transferred to mitochondria through the NADH shuttle system. By abolishing the NADH shuttle function, glucose-induced increases in NADH autofluorescence, mitochondrial membrane potential, and adenosine triphosphate content were reduced and glucose-induced insulin secretion was abrogated. The NADH shuttle evidently couples glycolysis with activation of mitochondrial energy metabolism to trigger insulin secretion.     

Control of swelling height of Si crystal by irradiating Ar beam

It has been found that ion implantation can induce a swelling (step-height) phenomenon on crystal surface. In this paper, we studied about the control of swelling height of Si crystal by irradiating Ar beam under various parameters (fluence, charge and energy). These irradiation parameters were regulated by an irradiation facility that enables to achieve the multiple ionization. For both charges, the swelling height was studied with the various fluencies of two different charges Ar(1+) and Ar(4+). The swelling height increased with increasing the fluence. The swelling height was also studied by changing energy of Ar(4+) beam. The swelling height increased by increasing the energy. The obtained swelling heights are understood base on the contribution of ion-beam induced defect, which is evaluated by SRIM. By comparing with the previous results, it was found that the expansion phenomena also depend on irradiated ion. The swelling structures were found to be stable more than two months. The present results have shown that this method of producing swelling structure indicates the potential application to fabricate 3-D nanostructure.     

Nanomechanical membrane-type surface stress sensor

Nanomechanical cantilever sensors have been emerging as a key device for real-time and label-free detection of various analytes ranging from gaseous to biological molecules. The major sensing principle is based on the analyte-induced surface stress, which makes a cantilever bend. In this letter, we present a membrane-type surface stress sensor (MSS), which is based on the piezoresistive read-out integrated in the sensor chip. The MSS is not a simple "cantilever," rather it consists of an "adsorbate membrane" suspended by four piezoresistive "sensing beams," composing a full Wheatstone bridge. The whole analyte-induced isotropic surface stress on the membrane is efficiently transduced to the piezoresistive beams as an amplified uniaxial stress. Evaluation of a prototype MSS used in the present experiments demonstrates a high sensitivity which is comparable with that of optical methods and a factor of more than 20 higher than that obtained with a standard piezoresistive cantilever. The finite element analyses indicate that changing dimensions of the membrane and beams can substantially increase the sensitivity further. Given the various conveniences and advantages of the integrated piezoresistive read-out, this platform is expected to open a new era of surface stress-based sensing.     

Determination of peptide phi angles in solids by relayed anisotropy correlation NMR

A solid state NMR method is presented for determination of a backbone dihedral angle phi in peptides, being based on the previously reported method, relayed anisotropy correlation (RACO) NMR [Y. Ishii et al., Chem. Phys. Lett. 256 (1996) 133]. In the present method, the 15N-1H and the 13C-1H dipolar tensors in the 1H-15N-13C-1H system are two-dimensionally (2D) correlated via polarization transfer from 15N to 13C under magic angle spinning (MAS). This method was applied to N-acetyl[1,2-13C,15N]D,L-valine, and the H-C-N-H dihedral angle was determined to be 154.0 +/- 1.4 degrees or 206.0 +/- 1.4 degrees, the former agreeing with the X-ray value of 154 +/- 5 degrees.     

Scoring resistance of TiC- and TiN-coated gears

In trying to clarify the effect of TiC and TiN coatings on the scoring resistance and wear characteristics of gears, various tests on rollers and gears coated with TiC and TiN coatings have been run. From the test results obtained by an Amsler machine and a power-circulating gear machine, it was found that the seizure resistance of the coated roller pair was larger than that of the uncoated roller pair. Further, the scoring resistance of the gear pair, which was combined with the coated wheel and uncoated pinion, was significantly large, and TiC and TiN coatings had a significant effect on increasing scoring resistance of the gears.