Synthesis and viscoelastic properties of new thermosetting resins having isocyanurate and oxazolidone rings in their molecular structures

A new type of thermosetting resin can be obtained from solventless varnishes composed of polyfunctional isocyanates and epoxides. The IR spectra show that the cured resins have isocyanurate and oxazolidone rings in their chemical structure, hence their name, isocyanurate–oxazolidone resins. The viscoelastic behavior of the cured resins can be varied considerably by selecting an appropriate reactant species and changing the equivalent ratio of the isocyanate and epoxy groups in the varnishes. Three relaxations, labeled α, β, and γ, characterize their dynamic mechanical spectra. The α-dispersion is due to the glass transition, the β-dispersion, to local mode motions of the backbone chains of resins, and the γ-dispersion, to the molecular motions of long alkyl chains. If certain additives are mixed into the varnishes before curing, microphase separation takes place during the reactions. The resins finally obtained have a peculiar physical structure in which rubber particles are dispersed throughout a matrix phase as confirmed by scanning electron-microscopic analysis and viscoelastic behavior.     

Conformation of single PMMA chain in uniaxially stretched film studied by scanning near-field optical microscopy

The conformation of the single polymer chain in uniaxially stretched poly(methyl methacrylate) (PMMA) films was studied by scanning near-field optical microscopy (SNOM), which enabled us to observe the elongated conformation of each polymer chain embedded in the film. The conformation of the individual PMMA chains was quantitatively evaluated from the fluorescence intensity distribution. Observation of films with different strains showed that the microscopic strain of the single chain was smaller than the macroscopic strain (?) of the film. Especially at the later stage of the deformation (? > 1.5), the PMMA chain was not stretched with the increase in the macroscopic elongation of the film, suggesting the presence of slipping of polymer chain on the course of stretching.     

Lubricant-Supplying Properties and Durability of Oil-Impregnated Polymers

Numerical optimization of tribological elements usually demands extended computations. The particle swarm optimization (PSO) method is known for its simple implementation and high efficiency in solving multifactor optimization problems. In this study, several parallel computing schemes using PSO for air foil bearing design are compared. The parallel programming models applied are multicore computing by OpenMP and many-core graphics processing unit (GPU) computing using Compute Unified Device Architecture (CUDA) and OpenACC. The best case was obtained when the OpenMP coding was applied at the algorithm level of optimization. The performance of CUDA was found to be compatible with OpenMP when parallel computing was used to solve the bearing model. Due to excess data communications computing using OpenACC was significantly slower than the other approaches. The parallel computing scheme recommended in this study is independent of PSO, which is applicable to tribological studies requiring global optimization analysis.     

Airborne freeboard measurements of sea ice and lake ice at the Sea of Okhotsk coast in 1993-95 by a laser altimeter

An airborne laser altimeter using a Nd:YAG laser was constructed to measure surface profiles of sea ice and frozen lakes. The measurements were conducted to develop a technique for estimating the ice amount of the sea ice in the Sea of Okhotsk off the northern shore of Hokkaido Island, Japan. Distributions of freeboards, mean elevations and ice concentrations were investigated from the data observed in 1993-95. Distribution functions of the ice freeboard changed considerably depending on ice concentrations in contrast with the decreasing function for the sea ice in the Arctic Ocean. The mean ice freeboard, however, correlated very well with the ice concentration, which is very important for estimating total ice amounts in regions of drifting ice. The surface roughness of a frozen lake was also observed and analysed.     

Exogenous ANP Treatment Ameliorates Myocardial Insulin Resistance and Protects against Ischemia–Reperfusion Injury in Diet-Induced Obesity

Increasing evidence suggests natriuretic peptides (NPs) coordinate interorgan metabolic crosstalk. We recently reported exogenous ANP treatment ameliorated systemic insulin resistance by inducing adipose tissue browning and attenuating hepatic steatosis in diet-induced obesity (DIO). We herein investigated whether ANP treatment also ameliorates myocardial insulin resistance, leading to cardioprotection during ischemia–reperfusion injury (IRI) in DIO. Mice fed a high-fat diet (HFD) or normal-fat diet for 13 weeks were treated with or without ANP infusion subcutaneously for another 3 weeks. Left ventricular BNP expression was substantially reduced in HFD hearts. Intraperitoneal-insulin-administration-induced Akt phosphorylation was impaired in HFD hearts, which was restored by ANP treatment, suggesting that ANP treatment ameliorated myocardial insulin resistance. After ischemia–reperfusion using the Langendorff model, HFD impaired cardiac functional recovery with a corresponding increased infarct size. However, ANP treatment improved functional recovery and reduced injury while restoring impaired IRI-induced Akt phosphorylation in HFD hearts. Myocardial ultrastructural analyses showed increased peri-mitochondrial lipid droplets with concomitantly decreased ATGL and HSL phosphorylation levels in ANP-treated HFD, suggesting that ANP protects mitochondria from lipid overload by trapping lipids. Accordingly, ANP treatment attenuated mitochondria cristae disruption after IRI in HFD hearts. In summary, exogenous ANP treatment ameliorates myocardial insulin resistance and protects against IRI associated with mitochondrial ultrastructure modifications in DIO. Replenishing biologically active NPs substantially affects HFD hearts in which endogenous NP production is impaired.     

Spot F positron source electro-deposited on a graphite rod

2.2 GBq of ¹⁸F (half-life 110 min) was effectively deposited on a graphite electrode of diameter 3 or 5 mm. The fraction of the electro-deposited ¹⁸F was as high as 97% of the total ¹⁸F produced in the solution. The fraction of the positrons emitted out of the electrode was 44% of the total β⁺. Thus, as much as 36% of the β⁺ from the produced ¹⁸F is available for the source of slow positron beams.     

Synthesis and properties of poly(2-adamantyl vinyl ether)-based optical plastics

Cationic polymerization of 2-adamantyl vinyl ether (2-vinyloxytricyclo[3.3.1.1^3,7]decane; 2-AdVE) and copolymerization of 2-AdVE with n-butyl vinyl ether (NBVE), 2-methoxyethyl vinyl ether (MOVE), or 2-(2-vinyloxyethoxy)ethyl acrylate (VEEA), vinyl ethers containing a flexible chain or a polymerizable group, were performed to obtain poly(vinyl ether) plastics for optical use. With the living cationic initiating systems such as isobutyl vinyl ether–acetic acid adduct/ethylaluminum sesquichloride (IBEA/Et_1.5AlCl_1.5) or the hydrogen chloride/zinc chloride (HCl/ZnCl₂), all the obtained copolymers had unimodal and relatively narrow molecular weight distributions (polydispersity ratio: M _w/M _n = ~1.5 at high conversion) throughout the copolymerizations. These results indicate that the copolymerizations of 2-AdVE with the three comonomers led to the statistical copolymers without contamination of homopolymers. With BF₃OEt₂ as an initiator, homopolymer of 2-AdVE and poly(2-AdVE)-based polymers, poly(2-AdVE-stat-NBVE), poly(2-AdVE-stat-MOVE), and poly(2-AdVE-stat-VEEA), were produced with high-molecular weights (M _n = 31,800–116,000) in toluene at ?30 °C in quantitative yield within 10 min. They have excellent thermal stability owing to their high glass transition and thermal decomposition temperatures. The transparency (86–91 %) and refractive index (1.52–1.53) of the molded polymers are similar to those of conventional optical plastics such as poly(methyl methacrylate) (PMMA) and polycarbonate (PC), whereas their specific gravity (1.09–1.12) and water absorption (0.06–0.17 %) are significantly lower than those of PMMA and PC. In addition, the Abbe number of poly(2-AdVE), poly(2-AdVE-stat-NBVE), and poly(2-AdVE-stat-MOVE) exceeded 60 and was higher than those of PMMA and PC, indicating that the poly(2-AdVE)-based plastics are very suitable for optical lens.     

Exercise and functional foods

Appropriate nutrition is an essential prerequisite for effective improvement of athletic performance, conditioning, recovery from fatigue after exercise, and avoidance of injury. Nutritional supplements containing carbohydrates, proteins, vitamins, and minerals have been widely used in various sporting fields to provide a boost to the recommended daily allowance. In addition, several natural food components have been found to show physiological effects, and some of them are considered to be useful for promoting exercise performance or for prevention of injury. However, these foods should only be used when there is clear scientific evidence and with understanding of the physiological changes caused by exercise. This article describes various "functional foods" that have been reported to be effective for improving exercise performance or health promotion, along with the relevant physiological changes that occur during exercise.     

Dramatic effect of dispersed carbon nanotubes on the mechanical and electroconductive properties of polymers derived from ionic liquids

Free-radical polymerization of an imidazolium ion-based ionic liquid bearing a methacrylate group, gelling with single-walled carbon nanotubes (SWNTs), allows fabrication of a mechanically reinforced, electroconductive soft material (bucky plastic). A film sample of this material displays an excellent conductivity of 1 S cm(-1) and a 120-fold enhancement of the Young's modulus at a 7 wt % content of SWNTs. The conductivity is temperature-dependent in the range 5-300 K, suggesting that the conductive process involves carrier hopping. Scanning electron and atomic force micrographs of a bucky plastic film display the presence of crosslinked networks consisting of finely dispersed SWNTs. Such nanotube networks, developed in the polymer matrix, likely suppress slipping of entrapped polymer molecules via a strong interfacial interaction and also facilitate intertubular carrier transport. Although a bucky plastic derived from a vinylimidazolium ion-based ionic liquid monomer shows a comparable conductivity to that of the methacrylate version, the film is brittle irrespective of the presence or absence of SWNTs.     

Generative adversarial network for road damage detection

Machine learning can produce promising results when sufficient training data are available; however, infrastructure inspections typically do not provide sufficient training data for road damage. Given the differences in the environment, the type of road damage and the degree of its progress can vary from structure to structure. The use of generative models, such as a generative adversarial network (GAN) or a variational autoencoder, makes it possible to generate a pseudoimage that cannot be distinguished from a real one. Combining a progressive growing GAN along with Poisson blending artificially generates road damage images that can be used as new training data to improve the accuracy of road damage detection. The addition of a synthesized road damage image to the training data improves the F‐measure by 5% and 2% when the number of original images is small and relatively large, respectively. All of the results and the new Road Damage Dataset 2019 are publicly available ( https://github.com/sekilab/RoadDamageDetector ).