Wear mechanisms of the rough form tools in the automatic screw machine test

Tool wear mechanisms of the rough form tools in the automatic screw machine test during machining of bismuth-bearing low carbon resulfurized free machining steel under practical machining conditions were investigated. Four mechanisms, namely mild adhesive wear, abrasive wear, continuous wear, and plastic deformation have been observed to play some roles simultaneously. Mild adhesive wear, which is a wear process taking place during detachment of an adhered chip, is believed to be enhanced by fatigue. Abrasive wear could take place either by oxide inclusions in the workpiece or by the primary carbide particles of the tool freed by some wear mechanisms. Continuous wear has been attributed to some type of atomic process, most probably dissolution of tool material into the chip. On the flank face, continuous, abrasive, and mild adhesive wear are believed to be the major wear mechanisms. On the rake face, continuous wear appears to be the predominant tool wear mechanism. Based on this investigation and consideration of the effect of built-up edge (BUE), reduction of cutting force, optimization of BUE size, stabilization of BUE, and reduction of oxide inclusions are found to be important for reduction of tool wear under practical machining conditions.     

Differential Effect of Azetidine Substitution in Firefly Luciferin Analogues

Replacing an N,N-dimethylamino group in a classical fluorophore with a four membered azetidine ring provides an improved luminescence quantum yield. Herein, we extended this strategy to bioluminescent firefly luciferin analogues and evaluated its general validity. For this purpose, four types of luciferin cores were employed, and a total of eight analogues were evaluated. Among these analogues, unexpectedly, only the benzothiazole core analogue benefited from an azetidine substitution and showed enhanced bioluminescence. In addition, fluorescence measurements revealed that an azetidine substitution improved the fluorescence quantum yield by 2.3-times compared to a N,N-dimethylamino group. These findings clarify the differential effects of azetidine substituents in luciferins and present one possible strategy for enhancing photon output in benzothiazole type luciferins through a synthetic approach.     

A hydrogen‐storing quinaldine polymer: nickel‐electrodeposition‐assisted hydrogenation and subsequent hydrogen evolution

Quinaldine‐substituted poly(acrylic acid) (PQD) and its hydrogenated 1,2,3,4‐tetrahydroquinaldine derivative (PHQD) were prepared, and a cycle of hydrogen fixing and hydrogen evolution in and from the polymer, respectively, is described. A PQD layer coated on a carbon substrate was electrochemically reduced or hydrogenated using water as a hydrogen source, accompanied by the electrodeposition of nickel microparticles in the polymer layer, to convert PQD to PHQD. The conversion efficiency was enhanced by coating PQD on the substrate as a scaffold of nickel electrodeposition, in comparison with that of quinaldine and PQD dissolved in the electrolyte. The formed PHQD evolved hydrogen by simply warming it in water containing an iridium complex catalyst. Hydrogen fixing and evolution under mild conditions could suggest a new system of hydrogen carriers. © 2017 Society of Chemical Industry     

Near-Infrared Bioluminescence Imaging with a through-Bond Energy Transfer Cassette

A coelenterazine (CTZ) analogue emitting near-infrared (NIR) bioluminescence was synthesized for through-bond energy transfer (TBET)-based imaging modalities. The analogue, named Cy5-CTZ, was prepared by conjugating cyanine-5 (Cy5) dye to CTZ through an acetylene linker. This novel derivative is intrinsically fluorescent and emits NIR-shifted luminescence upon reacting with an appropriate luciferase, the Renilla luciferase. This Cy5-CTZ substrate is optically stable in physiological samples and rapidly permeabilize through the plasma membrane into the cytosolic compartment of live cells.     

Drying behavior of sludge with drying accelerator

Abstract

For fuelization of high moisture content sludge, efficient sludge drying technique using a drying accelerator was investigated. In the experiment, drying accelerator types and drying conditions were changed and the effect of accelerator type and/or drying condition on sludge drying behavior was evaluated by analyzing drying characteristic curve. Depending on drying accelerator type, the addition of drying accelerator did not always exert superiority in drying rate, but sludge with added acrylic resin having low glass transition temperature (DA10) demonstrated significantly enhanced drying rate. Addition of surface activating agent (SAA) instead of resin type drying accelerator also enhanced the sludge drying rate. The highest drying rate was obtained by addition of DA10 and SAA together, and the sludge drying rate has significantly been augmented at the high drying temperature condition.     

On the fatigue fracture at adsorption/desorption of water in/from liquid-repellent nanoporous silica

In this work, fatigue fracture tests on liquid-repellent nanoporous silica micro-particles dispersed in water are reported; then, models of the grain cracking and fragmentation are proposed. Such tests can be regarded, from an external standpoint, as conducted under temporally variable but spatially uniform pressure distribution in the liquid surrounding the silica grains, or from an internal standpoint, as surface fatigue that occurs at the cyclical adsorption/desorption of water in/from the nanoporous particles. The test rig represents a compression–decompression cylinder divided into two chambers, one of constant volume and the other of variable volume. Silica is introduced inside the cavity of fixed volume, and a micro-filter is used to separate it from the chamber of variable volume, in which only water is supplied. Experimental results suggest that the fatigue fracture of silica particles occurs from the inside, explosion-like, oppositely to the previously reported implosion-like collapse of silica under wet pressurization. This is accompanied by enhancement of the hydrophilic silanol groups on the silica surface and by redistribution of the size of particles and pores. Critical numbers of cycles to achieve fracture of the silica particles obtained experimentally, and from the models of grain cracking and fragmentation, under cyclical pressurization, are in good agreement.     

5-GHz pulsed fiber Fabry-Pe/spl acute/rot laser mode-locked using carbon nanotubes

We demonstrate passive mode-locking of a short-cavity (/spl sim/2 cm) fiber Fabry-Pe/spl acute/rot laser by incorporating a carbon-nanotube-based saturable absorber. Stable pulses are generated with a pulsewidth as short as 0.68 ps at a repetition rate as high as 5.18 GHz. This is the smallest femtosecond fiber pulsed laser ever demonstrated to date.     

Identification of a Putative β-Arrestin Superagonist of the Growth Hormone Secretagogue Receptor (GHSR)

Ghrelin is a pleiotropic feeding hormone which also has a pivotal role in the central nervous system. Upon the activation of its receptor, growth hormone secretagogue receptor (GHSR), the Gα_q/11-mediated and the β-arrestin-mediated signaling pathways are activated. As the β-arrestin pathway is a potential drug target, there is a strong need for β-arrestin-biased GHSR modulators. Activation of the β-arrestin pathway should inhibit the Gα_q/11-mediated calcium flux through internalization of the receptor. Hence, we used the antagonistic activity in the calcium assay as the first screening for the β-arrestin activation. By conducting the second screening assay for the β-arrestin activation based on extracellular signal regulated kinase (ERK) 1/2 phosphorylation, we discovered a putative β-arrestin-biased superagonist. The activity of the compound was not completely blocked with the competitive antagonist, which implies that the effect is mediated, at least partly, by allosteric binding of the compound.     

Long‐term changes in Japanese women's facial skin color

It has been suggested that skin color changes not only with advancing age but also with the times. The purpose of this study was to investigate changes in Japanese women's facial skin color over 25 years, as well as the changes in skin pigmentation that affect skin color. First, skin color changes in terms of Munsell color values were investigated. A total of 3181 Japanese women residing in the greater Tokyo area were enrolled, and datasets were collected using spectrophotometers, designated as the 1991, 2001, 2005, and 2015 data. The mean Munsell hue, value, and chroma were calculated for each measurement year. Next, the concentrations of melanin and hemoglobin were calculated from spectral data, to investigate changes in skin pigmentations. Finally, Monte Carlo simulations were performed to verify that the suggested changes in skin pigmentations brought about skin color changes. As a result, skin color significantly changed toward high lightness, low saturation, and high yellowness from the 1991 data to the 2001 data. From the 2005 to 2015 data, the skin color distribution shifted toward lower saturation and increased redness. In addition, the concentration of hemoglobin decreased significantly from the 1991 data to the 2001 data, while the melanin concentration decreased significantly from the 2005 data to the 2015 data.