Sea urchins have a globiferous pedicellaria that stands from a test with a stalk on which lies a head made of three movable jaws with venom-injecting teeth. The globiferous pedicellariae of the flower sea urchin Toxopneustes pileolus, one of the most developed among sea urchins, are unique in that the jaws are provided with a jaw membrane that gives the pedicellaria an appearance of a flower when the jaws are open. We observed this membrane in an ionic liquid that does not require processes, such as fixation, dehydration, or coating with conductive materials, for observation with a scanning electron microscope. Using this technique, we discovered dumbbell-shaped ossicles, which consist of two spheres of similar size connected by a cylinder. The diameter of the sphere is 4-8 µm, and the total length of the ossicle is 10-20 µm. The jaw membrane is trimmed with an edge zone. The ossicles were found sparsely in the connective tissue of general part of the membrane, but in the edge zone their density was so high that neighboring ossicles were in close contact with each other. Some neighboring ossicles crossed their cylinders and some inserted one of their spheres to snugly fit in the gap between the spheres of neighboring ossicles. Their structural role is very likely in strengthening the jaw membrane, probably serving as fillers in the general part of the membrane; in the edge zone the interlocking of adjacent ossicles forms a loose network providing a firm frame for the head of the globiferous pedicellaria. When opened, the stiff frame prevents the membrane from sagging. When clasped, it works as a closed door, firmly keeping prey trapped.
Molecular mechanisms underlying the development and morphogenesis of oral epithelia, comprising the gustatory and nongustatory epithelium, remain unclear. Here, we show that Bcl11b, a zinc finger transcription factor, plays an important role in the development of lingual papillae, especially filiform papillae. In both gustatory and nongustatory epithelium, Bcl11b was expressed in keratin 14–positive epithelial basal cells, which differentiate into keratinocytes and/or taste cells. Loss of Bcl11b function resulted in abnormal morphology of the gustatory papillae: flattened fungiform papillae, shorter trench wall in the foliate and circumvallate papillae, and ectopic invagination in more than half of circumvallate papillae. However, Bcl11b loss caused no effect on differentiation of taste receptor cells. In nongustatory epithelium, the impact of Bcl11b deficiency was much more striking, resulting in a smooth surface on the tongue tip and hypoplastic filiform papillae in the dorsal lingual epithelium. Immunohistochemical analyses revealed that a keratinocyte differentiation marker, Tchh expression was severely decreased in the Bcl11b−/− filiform papillae. In addition, expression of Pax9, required for morphogenesis of filiform papillae and its downstream target genes, hard keratins, almost disappeared in the tongue tip and was decreased in the dorsal tongue of Bcl11b−/− mice. Gene expression analyses demonstrated a delayed onset of expression of epithelial differentiation complex genes, which disturbed barrier formation in the mutant tongue. These results indicate that Bcl11b regulates the differentiation of keratinocytes in the tongue and identify Bcl11b as an essential factor for the lingual papilla morphogenesis.
The self-assembly of ABA triblock copolymers comprising flexible amorphous poly(ethyl methacrylate) (PEMA, A block) and semiflexible liquid crystal (LC) polyester (B block) was investigated for amorphous block volume fractions (phi) ranging from 20% to 80%. Two copolymer series with different LC block molecular weights (M-n,M-LC) were examined. At phi < 55%, block copolymers with M-n,M-LC = 11 600 formed lamellar microdomains in which LC segments mostly extended along the lamella normal but folded to fit in the lamellae. When phi was augmented, the LC segment fold (N-fold) increased to enhance the interface between the LC and amorphous segments and counterbalanced the increase in amorphous lamella thickness by reducing the LC lamella thickness. When phi > 68%, the LC lamellae were divided into cubes, transforming into spheres in the PEMA matrix. When M-n,M-LC decreased to 6300, the copolymers showed similar morphology. However, the lamellae adopted zigzag configurations showing a greater tilting angle between the lamella normal to the LC chain axis with increasing phi. Thus, the LC and PEMA segments enhanced their interface by mutually sliding along the chain axis instead of increasing N-fold.
Solid-state lithium polymer secondary batteries (LPB) are fabricated with a two-electrode-type cell construction of Lilsolid-state polymer electrolyte (SPE)vertical bar LiFePO(4). Plasticizers of poly(ethylene glycol) (PEG)-borate ester (B-PEG) or PEG-aluminate ester (Al-PEG) are added into lithium-conducting SPEs in order to enhance their ionic conductivity, and lithium bis-trifluoromethansulfonimide (LiTFSI) is used as the lithium salt. An improvement of the electrochemical properties is observed upon addition of the plasticizers at an operation temperature of 60 degrees C. However, a decrease of discharge capacities abruptly follows after tens of stablecycles. To understand the origin of the capacity fading, electrochemical impedance techniques, ex-situ NMR and scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy (EDS) techniques are adopted. Alternating current (AC) impedance measurements indicate that the decrease of capacity retention in the LPB is related to a severe increase of the interfacial resistance between the SPE and cathode. in addition, the bulk resistance of the SPE film is observed to accompany the capacity decay. Ex situ NMR studies combined with AC impedance measurements reveal a decrease of Li salt concentration in the SPE film aftercycling. Ex situ SEM/EDS observations show an increase of concentration of anions on the electrode surface after cycling. Accordingly, the anions may decompose on the cathode surface, which leads to a reduction of the cycle life of the LPB. The present study suggests that a choice of Li salt and an increase of transference number is crucial for the realization of lithium polymer batteries.
Cross-sectional TEM images of carbon nanofibers formed through methane decomposition over Ni/SiO2 catalysts were observed by using all ultramicrotome. The TEM images indicated that carbon nanofibers have regular hexagonal prism structures.
The smectic X-1 phase formed from the banana 4-bromo-1,3-phenylenebis[4-(4-n-tetradecanoxyphenyliminomethyl)benzoate] (4Br-P-14-O-PIMB) molecule, possesses a distinct two-dimensional structure with a long-range density modulation of similar to 17.5 nm along the layer. The X-1 phase is formed upon cooling from the well-known B-2 phase, and then its characteristic modulated structure is retained at room temperature. A transmission electron microscopic (TEM) observation was performed for shadowed replica film which imprints the surface structure of the homeotropically aligned X, phase. The modulation was detected as clear stripes with periodicities ranging from 15 to 18 nm, which agree with the modulation length determined by X-ray measurement. The results confirm that the periodicity along the layer is not due to the simple density modulation occurring within a smooth layer, but can be explained by the layer undulation that creates the crests and troughs.