NMR and fluorescence studies of the self-association behavior of an amphiphilic polyanion bearing hydrocarbon and fluorocarbon hydrophobes

The association behavior of the terpolymers of sodium 2-acrylamido-2-methylpropanesulfonate (NaAMPS), N-dodecylmethacrylamide (DodMAm), and N-(2-(perfluorooctyl)ethyl)methacrylamide (PFOEMAm) (A/H(x)/F(y)) and their reference copolymers of NaAMPS and PFOEMAm (A/F(y)) was characterized using ¹⁹F and ¹H NMR, steady state fluorescence, and dynamic light scattering techniques in water (or D₂O) containing 0.1 M NaCl. The terpolymers formed micelle-like aggregates where hydrophobic microdomains are formed by hydrophobic associations among the perfluorooctylethyl (PFOE) and dodecyl (Dod) groups, the PFOE group exhibiting a stronger tendency for interpolymer association than the Dod groups. A careful analysis of the characterization data led to a conclusion that the hydrophobic microdomain formed from the terpolymer is microscopically phase separated into the fluorocarbon phase and hydrocarbon phase.     

Effect of charge accumulation on ac breakdown through a crackbetween two insulating walls

Breakdown in air through a crack between two insulating plane walls was investigated, using a knife edge, plane electrode configuration. A crack of width s was formed by two plane walls of PE blocks. The minimum crack width studied was 15 μm. The maximum electrode distance studied was 80 mm. The experiments were performed in air controlled at 20 to 25°C and 40 to 50%RH. In the region of the crack width 15>s>100 μm (A region), ac breakdown voltage (BDV) decreased with the decrease in s. In the region 0.1>s>1 mm (B region), BDV slightly increased with a decrease in the width. BDV decreased at the width of the crack where the magnitude of positive charge due to ac partial discharges (PD) was large. The magnitude of the negative charge due to PD was almost unchanged in the B region, but it increased in the A region. The surface voltage distribution on the wall suggested that positive charge accumulation on the wall and its neutralization play an important role of charge quantity of PD on the crack width     

Monoacylglycerols Activate Capsaicin Receptor, TRPV1

Transient receptor potential vanilloid subtype 1 (TRPV1) is known as capsaicin (CAP) receptor and activated by CAP. Activation of TRPV1 by CAP increases energy expenditure and thermogenesis in rodents or human. Therefore, TRPV1 may be target for energy expenditure enhancement and thermogenesis. To search for novel TRPV1 agonist, we screened 19 types of foods by using TRPV1-expressing HEK293 cells. TRPV1 was activated by hexane extract of wheat flour, and its functional compounds were 1-monoacylglycerols containing oleic, linoleic, and alpha-linolenic acids. Their potencies (EC50) were about 50 times larger than that of CAP and their efficacies (maximal response) were about half of that of CAP. TRPV1 was activated by 1-monoacylglycerols (MGs) having C18 and C20 unsaturated and C8-C12 saturated fatty acid (FA). Moreover, 2-MGs having C18 and C20 unsaturated FA acted on TRPV1 with the same potency. On the other hand, no activation of TRPV1 was induced by MGs having C16 and C18 saturated FA, di- or triacylglycerols of C18:1 FA. Pain-relating aversive responses were induced when TRPV1-activating 1-monoacylglycerols (50 mM) was administered subcutaneously into rat hind paw. These effects were inhibited by the co-injection of capsazepine (10 mM) which is a TRPV1 competitive antagonist. These results suggested that these 1-monoacylglycerols activate TRPV1 in vitro and in vivo.     

Identification of the Target Protein of Agelasine D,a Marine Sponge Diterpene Alkaloid,as an Anti‐dormant Mycobacterial Substance

One of the major reasons for the wide epidemicity of tuberculosis and for the necessity for extensive chemotherapeutic regimens is that the causative agent, Mycobacterium tuberculosis, has an ability to become dormant. Therefore, new lead compounds that are anti‐bacterial against M. tuberculosis in both active and dormant states are urgently needed. Marine sponge diterpene alkaloids, agelasines B, C, and D, from an Indonesian marine sponge of the genus Agelas were rediscovered as anti‐dormant‐mycobacterial substances. Based on the concept that the transformants over‐expressing targets of antimicrobial substances confer drug resistance, strains resistant to agelasine D were screened from Mycobacterium smegmatis transformed with a genomic DNA library of Mycobacterium bovis BCG. Sequence analysis of the cosmids isolated from resistant transformants revealed that the responsible gene was located in the genome region between 3475.051 and 3502.901 kb. Further analysis of the transformants over‐expressing the individual gene contained in this region indicated that BCG3185c (possibly a dioxygenase) might be a target of the molecule. Moreover, agelasine D was found to bind directly to recombinant BCG3185c protein (K_D 2.42 μm), based on surface plasmon resonance (SPR). This evidence strongly suggests that the BCG3185c protein is the major target of agelasine D, and that the latter is the anti‐mycobacterial substance against dormant bacilli.     

Polyamide4‐block‐poly(vinyl acetate) via a polyamide4 azo macromolecular initiator: Thermal and mechanical behavior,biodegradation, and morphology

A series of polyamide4‐block‐poly(vinyl acetate)s were synthesized by the radical polymerization of vinyl acetate (VAc) using an azo macromolecular initiator composed of polyamide4 (PA4). The block copolymers were investigated by examining their molecular weight, structure, thermal and mechanical properties, biodegradation, and the morphology of the film surface. The compositions and molecular weights (Mw) ranging from 46,800 to 163,700 g mol^?1 of the block copolymers varied linearly with increasing molar ratio of VAc to azo‐PA4. The block copolymers have high melting points of 248.2–262.5°C owing to PA4 blocks and heats of fusion, which were linearly dependent on the PA4 content. The mechanical properties of the block copolymers were monotonically dependent on the composition, i.e., increasing the PA4 content increased the tensile strength, whereas increasing the poly(vinyl acetate) content increased the elongation at break. The morphology of the block copolymers suggested the appearance of microphase separation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42466.     

Zn protoporphyrin IX is formed not from heme but from protoporphyrin IX

We examined the effects of exogenous myoglobin, a bivalent chelator, and nitrite on Zn protoporphyrin IX (ZPP) formation by using model systems. ZPP was formed in a model solution without addition of exogenous myoglobin. After incubation, the amount of ZPP in a model solution was increased but that of heme was not decreased compared with the amounts before incubation. Protoporphyrin IX (PPIX) instead of ZPP also accumulated in a model solution with addition of EDTA, but the amount of heme was not reduced. These results suggested that ZPP was not formed by the Fe–Zn substitution in heme but was formed by the insertion of Zn into PPIX, which was formed independently. The fact that the effects of various factors in model systems with/without addition of a bivalent chelator were similar suggested that ZPP formation was strongly affected by PPIX formation. Inhibition of PPIX formation by nitrite might be the reason for the low levels of ZPP in cured meats.     

Dynamic behavior of a solid particle bed in a liquid pool: SIMMER-III code verification

Dynamic behavior of solid particle beds in a liquid pool against pressure transients was investigated to model the mobility of core materials in a postulated disrupted core of a liquid metal fast reactor. A series of experiments was performed with a particle bed of different bed heights, comprising different monotype solid particles, where variable initial pressures of the originally pressurized nitrogen gas were adopted as the pressure sources. Computational simulations of the experiments were performed using SIMMER-III, a fast reactor safety analysis code. Comparisons between simulated and experimental results show that the physical model for multiphase flows used in the SIMMER-III code can reasonably represent the transient behaviors of pool multiphase flows with rich solid phases, as observed in the current experiments. This demonstrates the basic validity of the SIMMER-III code on simulating the dynamic behaviors induced by pressure transients in a low-energy disrupted core of a liquid metal fast reactor with rich solid phases.     

Vacuum electrical breakdown characteristics and surface condition of Ti electrodes with oxidation conditions

Outgassing from an electrode surface is regarded as a major factor leading to electrical breakdowns in vacuum. Recently oxidation treatment at 200/spl deg/C was reported as an effective means of reducing Ti outgassing. In this paper, we report our measurement and comparison of the electrical breakdown characteristics of Ti electrodes with different oxidation conditions (without oxidation, oxidation at 200/spl deg/C, oxidation at 450/spl deg/C). In addition, we analyzed electrode surfaces before and after breakdown experiments in situ with X-ray photoelectron spectroscopy (XPS). Before oxidation, we machined the electrode's surfaces to the roughness of 0.8 /spl mu/m Rmax with diamond turning. Breakdown experiments demonstrated that the breakdown field is highest at the first application of voltage to electrodes with oxidized at 200/spl deg/C. Before breakdown experiment, surface analysis revealed that all the sample electrodes had a large amount of carbon originating from the hydrocarbons of contaminants, and after the experiments, they revealed that the carbons had disappeared. To obtain breakdown characteristics of electrodes with smoother surfaces, we conducted experiments on electrodes with a surface roughness of 0.05 /spl mu/m Ra. For these electrodes, the breakdown field was higher at first breakdown; the repetitions required to achieve saturated breakdown fields were significantly fewer, and the amount of carbon on electrode surfaces before breakdown was less.     

Increase in capacitance and tan δ between conductors onprinted circuit board at low frequency due to ionic migration

An endurance test for a printed circuit board to ionic migration was carried out for 2000 h in a chamber controlled at 85°C and 85%RH. The capacitance C and tan δ between the conductors on the board were measured to find their correlation with ionic migration in the board. The measurement frequency of C and tan δ ranged from 1 to 1000 Hz. The configuration of the test circuit was designed according to IPC-SM-840. The material of the insulating board was fiberglass-reinforced epoxy resin. The distance between the Cu conductors was 0.165 mm, and 70 V dc was applied continuously. In the low frequency region (<30 Hz), C and tan δ gradually increase after ~800 h voltage application. During the gradual increase, steeply transient increases in C and tan δ are detected at about the same time when a deposit was seen to have formed on the board between the conductors, although no significant decrease in insulating resistance between the conductors is observed. It was confirmed that the deposit could be detected early from the steep increases in C and tan δ in the low frequency region. In the high frequency region (>30 Hz), on the other hand, gradual slight increases are observed from ~1100 h after voltage application, but no steep increases. The dependence of C and tan δ on frequency at the measurement is due to the low mobility of Cu ions in the water film on the insulating board