Extremely Rapid Self-Healable and Recyclable Supramolecular Materials through Planetary Ball Milling and Host–Guest Interactions

The host–guest interaction as noncovalent bonds can make polymeric materials tough and flexible based on the reversibility property, which is a promising approach to extend the lifetime of polymeric materials. Supramolecular materials with cyclodextrin and adamantane are prepared by mixing host polymers and guest polymers by planetary ball milling. The toughness of the supramolecular materials prepared by ball milling is approximately 2 to 5 times higher than that of supramolecular materials prepared by casting, which is the conventional method. The materials maintain their mechanical properties during repeated ball milling treatments. They are also applicable as self-healable bulk materials and coatings, and they retain the transparency of the substrate. Moreover, fractured pieces of the materials can be re-adhered within 10 min. Dynamic mechanical analysis, thermal property measurements, small-angle X-ray scattering, and microscopy observations reveal these behaviors in detail. Scars formed on the coating disappear within a few seconds at 60 °C. At the same time, the coating shows scratch resistance due to its good mechanical properties. The ball milling method mixes the host polymer and guest polymer at the nano level to achieve the self-healing and recycling properties.     

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.     

Effects of Dietary Cholesterol on Tissue Ceramides and Oxidation Products of Apolipoprotein B-100 in ApoE-Deficient Mice

Oxidized LDL (oxLDL) has been shown to activate the sphingomyelinase pathway producing ceramide in vascular smooth muscle cells. Therefore ceramide, which is a biologically active lipid causing apoptosis in a variety of cells, may be involved in the apoptotic action of oxLDL. In this study, we examined whether cholesterol enriched diets affected ceramide metabolism and oxidation product of LDL, represented by degradation of apolipoprotein B-100 (apoB) in apoE-deficient (apoE^−/−) mice. ApoE^−/− and wild type mice were fed a standard (AIN-76) diet or 1% cholesterol-enriched diet for 8 weeks. Tissue ceramide levels were analyzed using electrospray tandem mass spectrometry (LC-MS/MS). Ceramide levels in the plasma and the liver of apoE^−/− mice were intrinsically higher than those of the wild type. In apoE^−/− mice, dietary cholesterol significantly increased several ceramides and degradation products of apoB in plasma compared to those fed the control diet. Dietary cholesterol did not affect tissue ceramide levels in the wild type mice. Based on these results, plasma ceramides possibly correlate with the increase in LDL oxidation and are a risk factor for atherosclerosis.     

Transport of carnitine and acetylcarnitine by carnitine/organic cation transporter (OCTN) 2 and OCTN3 into epididymal spermatozoa

Carnitine and acetylcarnitine are important for the acquisition of motility and maturation of spermatozoa in the epididymis. In this study, we examined the involvement of carnitine/organic cation transporter (OCTN) in carnitine and acetylcarnitine transport in epididymal spermatozoa of mice. Uptake of both compounds by epididymal spermatozoa was time-dependent and partially Na(+)-dependent. Kinetic analyses revealed the presence of a high-affinity transport system in the spermatozoa, with K(m) values of 23.6 and 6.57 muM for carnitine and acetylcarnitine respectively in the presence of Na(+). Expression of OCTN2 and OCTN3 in epididymal spermatozoa was confirmed by immunofluorescence analysis. The involvement of these two transporters in carnitine and acetylcarnitine transport was supported by a selective inhibition study. We conclude that both Na(+)-dependent and -independent carnitine transporters, OCTN2 and OCTN3, mediate the supply of carnitine and acetylcarnitine to epididymal spermatozoa in mice.     

Functionalized imidazolium ionic liquids as electrolyte components of lithium batteries

Some basic properties and compatibility toward lithium electrode for electrolytes based on substituted imidazolium ionic liquid have been investigated. The ionic liquids having imidazolium cation substituted by methylcarboxyl or cyano group suffers from low conductivity. However, reversible lithium deposition–dissolution process was observed in electrolytes based on these electrolytes. In particular, lithium salt solution in cyanomethyl-substituted imidazolium ionic liquid provided similar cycle efficiency to conventional organic solvent electrolyte at constant-current condition. The mixed ionic liquid electrolyte containing the cyanomethyl-substituted ionic liquid also provided good cycle performance despite of containing large amount of 1-ethyl-3-methyl imidazolium (EMI)-based ionic liquid. Such mixed electrolyte system serves both the stability of lithium electrode process and valid conductivity for practical use.     

Proposal for an engineering definition of a fatigue crack initiation unit for evaluating the fatigue limit on the basis of crystallographic analysis of pearlitic steel

In this study, in order to define a fatigue crack initiation unit, the relationship between the fatigue crack initiation process and the crystal structure in the pearlitic steel used for railroad rails was examined and fatigue tests, focusing on crack initiation, were performed. The fracture surfaces were analyzed using a scanning electron microscope (SEM) and electron backscatter diffraction (EBSD). The crystal structure of the pearlitic steel is composed of “pearlitic colonies” that have the same lamellar structure direction and “pearlitic blocks” that have the same ferrite crystal direction. The SEM and EBSD results revealed that the crack initiation depends on the pearlitic colonies. Therefore, we defined the characteristic dimension for fatigue crack initiation as the pearlitic colony size. However, for safety purposes, the pearlitic block size should be considered the engineering definition of the fatigue crack initiation unit, since decreasing the pearlitic block size should cause an improvement in the fatigue limit of pearlitic steel.     

Direct demonstration of the presence of zinc in the acetone-extractable red pigment from Parma ham

We studied the presence of zinc in the red pigment extracted from Parma ham by scanning electron microscopy/energy dispersive X-ray microanalysis. The large peak of about 8.6keV and the small peaks at about 1.1keV and 9.5keV were derived from K(α), L(α1) and K(β) X-ray of zinc, respectively. Thus, the results suggested that zinc existed in the red pigment extracted from Parma ham. In contrast, the K(α) X-ray peak of iron (6.4keV) was not detected and the K(α) X-ray peak of magnesium (1.3keV) was hardly detected. These results revealed that the red pigment contained not iron but zinc. In addition to the results of mass analysis in previous studies, the red pigment was demonstrated to be zinc protoporphyrin IX.     

Enhanced accumulation of anthocyanin in cultured strawberry cells by repetitive feeding of L-phenylalanine into the medium

L-Phenylalanine (Phe), biosynthetic precursor of anthocyanin, was repetitively added into a suspension culture of strawberry cells, constantly producing anthocyanins. In the repetitive feeding culture, the maximum anthocyanin accumulation per culture was 30% and 81% higher than those in a single Phe-feeding culture and non-feeding culture, respectively. This means that the inhibitory effect of Phe on cell growth was successfully avoided and its intracellular free-state concentration was maintained at a higher level by the repetitive feeding of L-phenylalanine at relatively lower intra-medium concentration. These results support the phenylalanine pool hypothesis which states that the intracellular L-phenylalanine level determines anthocyanin production. However, it was also suggested that there exist other restrictions controlling intracellular anthocyanin accumulation.     

Disconnection detection using earth capacitance measurement in photovoltaic module string

A disconnection detection method using an earth capacitance measurement in photovoltaic (PV) module string was experimentally studied. In the experiments with disconnections between PV modules in the string, the earth capacitance of the string was increased in proportion to the module number, and this feature resulted in that the disconnection position between the modules could be estimated by comparing the earth capacitance value of the failed string with that of the good string. Since the earth capacitance was not affected by the irradiance change, the detection method could be applied anytime to locate the disconnection position in the string without the effect of the irradiance change. Moreover, this method could be applied not only to the string consisting of the crystalline Si modules but also to the string consisting of the amorphous Si modules. Copyright © 2008 John Wiley & Sons, Ltd.