Effect of tool stiffness upon tool wear in high spindle speed milling using small ball end mill

Longer tool life can be tentatively achieved at a higher feed rate using a small ball end mill in high spindle speed milling (over several tens of thousands of revolutions per minute), although the mechanism by which tool life is improved has not yet been clarified. In the present paper, the mechanism of tool wear is investigated with respect to the deviation in cutting force and the deflection of a ball end mill with two cutting edges. The vector loci of the cutting forces are shown to correlate strongly with wear on both cutting edges of ball end mills having various tool stiffnesses related to the tool length. The results clarified that tool life can be prolonged by reducing tool stiffness, because the cutting forces are balanced, resulting in even tool wear on both cutting edges as tool stiffness is lowered to almost the breakage limit of the end mill. A ball end mill with an optimal tool length showed significant improvement in tool life in the milling of forging die models.     

The Dipeptidyl Peptidase-4 Inhibitor Teneligliptin Attenuates Hepatic Lipogenesis via AMPK Activation in Non-Alcoholic Fatty Liver Disease Model Mice

Non-alcoholic fatty liver disease (NAFLD), which is strongly associated with metabolic syndrome, is increasingly a major cause of hepatic disorder. Dipeptidyl peptidase (DPP)-4 inhibitors, anti-diabetic agents, are expected to be effective for the treatment of NAFLD. In the present study, we established a novel NAFLD model mouse using monosodium glutamate (MSG) and a high-fat diet (HFD) and investigated the effects of a DPP-4 inhibitor, teneligliptin, on the progression of NAFLD. Male MSG/HFD-treated mice were divided into two groups, one of which received teneligliptin in drinking water. Administration of MSG and HFD caused mice to develop severe fatty changes in the liver, but teneligliptin treatment improved hepatic steatosis and inflammation, as evaluated by the NAFLD activity score. Serum alanine aminotransferase and intrahepatic triglyceride levels were significantly decreased in teneligliptin-treated mice (p < 0.05). Hepatic mRNA levels of the genes involved in de novo lipogenesis were significantly downregulated by teneligliptin (p < 0.05). Moreover, teneligliptin increased hepatic expression levels of phosphorylated AMP-activated protein kinase (AMPK) protein. These findings suggest that teneligliptin attenuates lipogenesis in the liver by activating AMPK and downregulating the expression of genes involved in lipogenesis. DPP-4 inhibitors may be effective for the treatment of NAFLD and may be able to prevent its progression to non-alcoholic steatohepatitis.     

Spin-vortices and Spin-vortex-induced Loop Currents in the Pseudogap Phase of Cuprates

We explain several anomalous phenomena observed in the pseudogap phase of hole-doped cuprates based on the recently proposed spin-vortex superconductivity theory. In this theory, doped-holes become almost immobile small polarons, and spin-vortices are formed with those small polarons as their centers. A Hartree?CFock field for conduction electrons that is optimized for the interaction energy of local moments is derived; it contains a fictitious magnetic field arising from spin-vortices, and yields current carrying states. The obtained currents are loop currents around spin-vortices, i.e., the spin-vortex-induced loop currents (SVILCs), and a collection of them produces a macroscopic current. The SVILC explains (1) nonzero Kerr rotation in zero-magnetic field after exposed in a strong magnetic field; (2) the change of the sign of the Hall coefficient with temperature change; (3) the suppression of superconductivity in the x=1/8 static-stripe ordered sample; and (4) a large anomalous Nernst signal, including its sign-change with temperature change. We show that the hourglass-shaped magnetic excitation spectrum is the evidence for the existence of spin-vortices. We further argue that the ??Fermi-arc?? in the ARPES is a support for the presence of localized moments in the bulk; a disconnected arc-shaped Fermi surface is obtained by assuming an antiferromagnetic interaction between the localized moments in the bulk and itinerant electrons in the surface region.     

Adsorption characteristics of bovine serum albumin onto alumina with a specific crystalline structure

Bone cement containing alumina particles with a specific crystalline structure exhibits the ability to bond with bone. These particles (AL-P) are mainly composed of delta-type alumina (δ-Al₂O₃). It is likely that some of the proteins present in the body environment are adsorbed onto the cement and influence the expression of its bioactivity. However, the effect that this adsorption of proteins has on the bone-bonding mechanism of bone cement has not yet been elucidated. In this study, we investigated the characteristics of the adsorption of bovine serum albumin (BSA) onto AL-P and compared them with those of its adsorption onto hydroxyapatite (HA), which also exhibits bone-bonding ability, as well as with those of adsorption onto alpha-type alumina (α-Al₂O₃), which does not bond with bone. The adsorption characteristics of BSA onto AL-P were very different from those onto α-Al₂O₃ but quite similar to those onto HA. It is speculated that BSA is adsorbed onto AL-P and HA by interionic interactions, while it is adsorbed onto α-Al₂O₃ by electrostatic attraction. The results suggest that the specific adsorption of albumin onto implant materials might play a role in the expression of the bone-bonding abilities of the materials.     

An analysis of generation mechanisms of transitional peak current in sense-emitter current for IGBTs with current sense and techniques to remove it

It is important to remove the transitional peak current in sense-emitter current which is due to dynamic current-sharing during turn-on for a design of IGBTs with current-sense used protection against overcurrent and short circuit. But this analysis has been scarcely investigated. This paper clarifies generation mechanisms of the transitional peak current by simulations and experiments using a parallel operation model and reports on techniques to remove it. The following results were obtained. (1) In the two paralleling devices model which consists of a sense cell and main cells, the transitional peak current occurs during turn-on when a sense cell turns on faster than main cells. In this case, the main parameters that effect dynamic currents imbalance are gate resistance (Rg) and gate threshold voltage (Vth). (2) In dynamic currents imbalance based on individual Rg and Vth among main cells, it may be treated as a two-paralleling devices model which consists of a sense cell with Rgs and Vths, and main cells with average values Rgm and Vthm. (3) The transitional peak current can be removed by the design of Rgs and Vths in a sense cell are larger than average values of Rgm and Vthm in main cells. (4) On trial IGBTs with current sense Vths in a sense cell is different from the average-value Vthm in main cells to change impurity concentrations of each channel. It was confirmed that the transitional peak current in sense-emitter current can be removed by the design that Vths in a sense cell is larger than average value Vthm in main cells.     

Structural properties and phase diagram of La2MO4+δ (M=Ni,Cu)

The phase diagram of La₂MO_4+δ (M=Ni, Cu) and the temperature dependence of orthorhombicity for several orthorhombic phases were investigated byin situ X-ray powder diffraction. A successive phase transition, tetragonalI4/mmm-[second-order] → orthorhombicBmab-[ first-order] → orthorhombicPccn, was observed in La₂NiO_4.00. The orthorhombicity of thePccn phase decreases on cooling in contrast to that of theBmab phase. The orthorhombic La₂NiO_4.15 (Fmmm) shows a weak temperature dependence of orthorhombicity and exhibits a first-order phase transition to the tetragonalI4/mmm phase on heating. As judged from the temperature dependence of orthorhombicity, superconducting La₂CuO_4.07, which results from the phase separation in the high-pressure oxygenated sample, isBmab, while La₂CuO_4.07 prepared by electrochemical oxidation at room temperature isFmmm.     

Electrical conductivities of M3P2O8 (M = Ca,Ba)

Two-probe conductivity measurements made for M₃P₂O₈ (M = Ca, Ba) suggested that the electrical conduction of these phosphates would primarily be due to the migration of Ca²⁺ and Ba²⁺ ions. At relatively low temperatures and high oxygen partial pressures, in contrast to Ca₃P₂O₈, however, Ba₃P₂O₈ shows partial electronic conduction.     

System identification theory of the thermal network model and an application for multi-chamber airflow measurement

A comprehensive theory of multi-chamber air infiltration measurement using a single tracer gas is introduced from the general stand point of system identification. The thermal network model can be applied not only to the temperature transfer and diffusion system but also to the tracer gas transfer system. This model is formulated mathematically in a state equation. The coefficients in the state equation represent airflow rates of infiltration. Two theories for estimating these coefficients are deduced from the least square. These are batch and successive identification. Further, the evaluation method of estimation errors that has been so far insufficient is described. Finally, the accuracy and the practicality of the theory are confirmed by the actual measurement system and experiments.