Vibration analysis and cutting simulation of structural nonlinearity for machine tool

The dynamic behavior of a machine tool is affected by the forces applied to the structure. However, cutting processes have been analyzed considering the linear systems in most of the studies so far. In this study, a machine tool structure was excited by using an electromagnetic shaker and the force-dependant frequency response characteristics were measured. Based on the measured result, the nonlinear characteristics of the machine tool structure was identified, and a machine tool with the nonlinear characteristics was mathematically reproduced, which enabled to analyse the nonlinear frequency response characteristics and simulate cutting processes.     

Enzymatic enrichment of arachidonic acid from Mortierella single-cell oil

An attempt was made to enrich arachidonic acid (AA) from Mortierella single-cell oil, which had an AA content of 25%. The first step involved the hydrolysis of the oil with Pseudomonas sp. lipase. A mixture of 2.5 g oil, 2.5 g water, and 4000 units (U) Pseudomonas lipase was incubated at 40°C for 40 h with stirring at 500 rpm. The hydrolysis was 90% complete after 40 h, and the resulting free fatty acids (FFA) were extracted with n-hexane (AA content, 25%; recovery of AA, 91%). The second step involved the selective esterification of the fatty acids with lauryl alcohol and Candida rugosa lipase. A mixture of 3.5 g fatty acids/lauryl alcohol (1:1, mol/mol), 1.5 g water, and 1000 U Candida lipase was incubated at 30°C for 16 h with stirring at 500 rpm. Under these conditions, 55% of the fatty acids were esterified, and the AA content in the FFA fraction was raised to 51% with a 92% yield. The long-chain saturated fatty acids in the FFA fraction were eliminated as urea adducts. This procedure raised the AA content to 63%. To further elevate the AA content, the fatty acids were esterified again in the same manner with Candida lipase. The repeated esterification raised the AA content to 75% with a recovery of 71% of its initial content.     

The effect of material combinations and relative crack size to the stress intensity factors at the crack tip of a bi-material bonded strip

Several types of singular stress fields may appear at the corner where an interface between two bonded materials intersects a traction-free edge depending on the material combinations. Since the failure of the multi-layer systems often originates at the free-edge corner, the analysis of the edge interface crack is the most fundamental to simulate crack extension. In this study, the stress intensity factors for an edge interfacial crack in a bi-material bonded strip subjected to longitudinal tensile stress are evaluated for various combinations of materials using the finite element method. Then, the stress intensity factors are calculated systematically with varying the relative crack sizes from shallow to very deep cracks. Finally, the variations of stress intensity factors of a bi-material bonded strip are discussed with varying the relative crack size and material combinations. This investigation may contribute to a better understanding of the initiation and propagation of the interfacial cracks.     

One-step synthesis of magnetically recyclable Au/Co/Fe triple-layered core-shell nanoparticles as highly efficient catalysts for the hydrolytic dehydrogenation of ammonia borane

Magnetically recyclable Au/Co/Fe core-shell nanoparticles (NPs) have been successfully synthesized via a one-step in situ procedure. Transmission electron microscope (TEM), energy dispersive X-ray spectroscopic (EDS), and electron energy-loss spectroscopic (EELS) measurements revealed that the trimetallic Au/Co/Fe NPs have a triple-layered core-shell structure composed of a Au core, a Co-rich inter-layer, and a Fe-rich shell. The Au/Co/Fe core-shell NPs exhibit much higher catalytic activities for hydrolytic dehydrogenation of ammonia borane (NH₃BH₃, AB) than the monometallic (Au, Co, Fe) or bimetallic (AuCo, AuFe, CoFe) counterparts.      

Prenylated chalcones 4-hydroxyderricin and xanthoangelol stimulate glucose uptake in skeletal muscle cells by inducing GLUT4 translocation

Scope: Glucose uptake in skeletal muscle is crucial for glucose homeostasis. Methods and results: Insulin and muscle contraction increase glucose uptake accompanied by the translocation of glucose transporter (GLUT) 4. In a search for promising foods, which can increase glucose uptake in skeletal muscle, we screened for active polyphenols by assaying for uptake of 2‐deoxyglucose (2DG) in rat L6 muscle cells. Among 37 compounds, 4‐hydroxyderricin and xanthoangelol, prenylated chalcones abundant in Ashitaba (Angelica keiskei Koidzumi, family Apiaceae), significantly increased 2DG uptake in L6 cells by 1.9‐fold at 10 μM, compared with the level in DMSO‐treated control cells. Next, we investigated the effect of these chalcones on the translocation of GLUT4 and its underlying mechanisms. The chalcones increased the GLUT4 level in the plasma membrane of L6 cells, but activated neither protein kinase C ζ/λ, Akt, nor adenosine monophosphate‐activated protein kinase, all of which regulate the GLUT4 translocation. Interestingly, the oral administration of a titrated chalcone‐enriched Ashitaba extract containing 150.6 mg/g (dry base) of 4‐hydroxyderricin and 146.0 mg/g (dry base) of xanthoangelol suppressed acute hyperglycemia in oral glucose tolerance tests of mice. Conclusions: Ashitaba is a promising functional food for the maintenance of the blood glucose level by inducing skeletal muscle‐associated glucose uptake.     

A Characteristic Reaction of Lignin in Ionic Liquids; Glycelol Type Enol-Ether as the Primary Decomposition Product of β-O-4 Model Compound

Abstract

Guaiacylglycerol-β-guaiacyl ether (GG), which contains a predominant inter-unit linkage of lignin, could be converted into a corresponding glycerol type enol-ether (EE), 3-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxyphenoxy)-2-propenol, by the heat treatment in ionic liquids. EE is believed to be the unstable intermediate of the lignin decomposition process under acidic and alkaline conditions. By contrast, EE could be isolated as a relatively stable compound from the reaction mixture of ionic liquids. EE was formed as a primary reaction product in all ionic liquids used in this research under the temperature conditions of 120°C, although the decomposition rate and secondary decomposition products of GG varied with the ionic liquid used. NMR data suggested that dehydration reaction of GG progressed stereospecifically and [Z] isomer was predominantly formed (stereoselectivety of [Z] is higher than 90%).     

Endothelial Dysfunction Accelerates Impairment of Mitochondrial Function in Ageing Kidneys via Inflammasome Activation

Chronic kidney disease is a common problem in the elderly and is associated with increased mortality. We have reported on the role of nitric oxide, which is generated from endothelial nitric oxide synthase (eNOS), in the progression of aged kidneys. To elucidate the role of endothelial dysfunction and the lack of an eNOS-NO pathway in ageing kidneys, we conducted experiments using eNOS and ASC-deficient mice. C57B/6 J mice (wild type (WT)), eNOS knockout (eNOS KO), and ASC knockout (ASC KO) mice were used in the present study. Then, eNOS/ASC double-knockout (eNOS/ASC DKO) mice were generated by crossing eNOS KO and ASC KO mice. These mice were sacrificed at 17−19 months old. The Masson positive area and the KIM-1 positive area tended to increase in eNOS KO mice, compared with WT mice, but not eNOS/ASC DKO mice. The COX-positive area was significantly reduced in eNOS KO mice, compared with WT and eNOS/ASC DKO mice. To determine whether inflammasomes were activated in infiltrating macrophages, the double staining of IL-18 and F4/80 was performed. IL-18 and F4/80 were found to be co-localised in the tubulointerstitial areas. Inflammasomes play a pivotal role in inflammaging in ageing kidneys. Furthermore, inflammasome activation may accelerate cellular senescence via mitochondrial dysfunction. The importance of endothelial function as a regulatory mechanism suggests that protection of endothelial function may be a potential therapeutic target.     

The inhibitory action of long-chain fatty acids on the DNA binding activity of p53

The in vitro relationship between human p53 DNA binding domain (p53 DBD) and FA was investigated. We found that saturated and monounsaturated long-chain FA inhibited the double-stranded DNA (dsDNA) binding activity of p53 DBD. The strongest inhibitors of saturated and unsaturated FA were docosanoic acid (22∶0) and cis-12-heneicosenoic acid (21∶1n−9), respectively. n-Octadecane, trans-unsaturated FA, and FAME had no influence on the binding activity of p53 DBD, showing that the FA structures such as one or no double bond of cis configuration, hydrocarbon chain of length C₂₀ to C₂₂, and free carboxyl groups are important for the inhibition. The inhibitory effect of the R248A mutant of p53 DBD by saturated FA was as strong as that for wild-type p53 DBD. On the other hand, the inhibition of dsDNA binding activity of the same mutant by the cis-configuration of monounsaturated FA was weaker than that for the wild type. These results suggest that R248 in p53 DBD is important for binding to monounsaturated FA. This is the first report that long-chain FA act as dsDNA binding inhibitor of p53, and it could be considered that FA in the cell membrane might regulate the activity of p53 for cell division, cell-cycle checkpoint, and tumor suppression.