Integrated Fluorescent Nanoprobe Design for High-Speed In Vivo Two-Photon Microscopic Imaging of Deep-Brain Vasculature in Mice

High-speed two-photon microscopy can be used to analyze vascular dynamics in living animals and is essential for the understanding of brain diseases. Recent advances in fluorescent probes/optical systems have allowed successful imaging of the hippocampal vasculature in the deep brain of mice (1 mm from the brain surface) under low-speed conditions (1–2 fps); however, using high-speed techniques (>30 fps), observation of the deep-brain vasculature is still challenging. Here, a new nanoemulsion that encapsulates thousands of red-emissive pyrene dye molecules while maintaining their high two-photon brightness [1.5 × 10² GM (GM = 10⁻⁵⁰ cm⁴·s·photon⁻¹·molecule⁻¹) at 960 nm excitation] and delivers a large amount of such pyrene dyes (65 nmol) into the blood vessels of mice is developed. Remarkably, the nanoprobe is found to exploit the inherent performance of a commonly used Ti:sapphire excitation laser and a sensitive gallium arsenide phosphide nondescanned fluorescence detector to the limit, enabling visualization of the brain vasculature under the cortex region of mice (up to 1.5 mm) under very low-speed conditions. As a highlight, such a nanoprobe is successfully used to directly observe the blood flow in the hippocampal CA1 region (1.1 mm) through high-speed resonant scanning (120 fps).     

Structures of Biological Minerals in Dental Research

Structural features of some calcium phosphates of biological interest are described. Structure of hydroxyapatite (OHAp), considered as the prototype for the inorganic component of bones and teeth is discussed with respect to the kinds and locations of ionic substitutions. Octacalcium phosphate (OCP), is a probable precursor in biological mineralization. OCP has a layer type structure, with one layer quite similar to that of OHAp and the other, a hydrated layer consisting of more widely spaced Ca, and PO₄ ions and the water molecules. The closeness of fit in the apatitic layers of OCP and OHAp accounts for the epitaxial, interlayered mixtures formed by these compounds and the in situ conversion of OCP to OHAp. Possible roles of OCP in biological mineralization are discussed.     

Aggregation of Cystatin C Changes Its Inhibitory Functions on Protease Activities and Amyloid β Fibril Formation

Cystatin C (CST3) is an endogenous cysteine protease inhibitor, which is implicated in cerebral amyloid angiopathy (CAA). In CAA, CST3 is found to be aggregated. The purpose of this study is to investigate whether this aggregation could alter the activity of the protein relevant to the molecular pathology of CAA. A system of CST3 protein aggregation was established, and the aggregated protein was characterized. The results showed that CST3 aggregated both at 80 °C without agitation, and at 37 °C with agitation in a time-dependent manner. However, the levels of aggregation were high and appeared earlier at 80 °C. Dot-blot immunoassay for oligomers revealed that CST3 could make oligomeric aggregates at the 37 °C condition. Electron microscopy showed that CST3 could make short fibrillary aggregates at 37 °C. Cathepsin B activity assay demonstrated that aggregated CST3 inhibited the enzyme activity less efficiently at pH 5.5. At 7.4 pH, it lost the inhibitory properties almost completely. In addition, aggregated CST3 did not inhibit Aβ_1-40 fibril formation, rather, it slightly increased it. CST3 immunocytochemistry showed that the protein was positive both in monomeric and aggregated CST3-treated neuronal culture. However, His6 immunocytochemistry revealed that the internalization of exogenous recombinant CST3 by an astrocytoma cell culture was higher when the protein was aggregated compared to its monomeric form. Finally, MTT cell viability assay showed that the aggregated form of CST3 was more toxic than the monomeric form. Thus, our results suggest that aggregation may result in a loss-of-function phenotype of CST3, which is toxic and responsible for cellular degeneration.     

Effect ofin Situ cooling on superconductivity of artificially layered BSCCO films with 2223 structure

Thin BSCCO films with the 2223 structure were deposited onto MgO substrate kept at 665°C by applying a sequential sputtering method using metallic Bi and Sr-Ca-Cu-O targets. The resultant films were then cooled under various oxygen partial pressures and cooling rates. It was found that the oxygen partial pressure and substrate temperature during cooling affect significantly the development of superconductivity of the as-deposited films. When the films were cooled stepwise under a critical oxygen partial pressure around 0.3 torr, the as-deposited films showed either superconductivity or nonsuperconductivity behavior. HRTEM images of the films showed no essential difference in the modulated structure, suggesting that the excess oxygen in the Bi-O double layers is the same and not the cause of the different superconducting behavior in the as-deposited films.     

The existence of the 1,2-dicarbonyl compounds glyoxal,methyl glyoxal and diacetyl in autoxidised edible oils

The 1,2-dicarbonyl compounds glyoxal, methyl glyoxal and diacetyl which are known to be mutagens without metabolic activation in the Salmonella typhimurium TA100 system, were detected in autoxidised edible oils (sesame, safflower and sardine oil). The method is based on the fact that the 1,2-dicarbonyl compounds react with 4-chloro-1,2-phenylenediamine to give 6-chloroquinoxaline derivatives, which can be detected by ⁶³Ni ECD-gas chromatography. Glyoxal, methyl glyoxal and diacetyl were detected at 4.7, 7.0 and 1.6 μg g^?1, respectively, in 20 h autoxidised methyl linolenate. Glyoxal, methyl glyoxal and diacetyl were also detected at 6.5, 7.0 and 3.1 μg g^?1, respectively, in 30 h autoxidised sardine oil.     

Design of polymers with metallic properties: Substituted polyperylene and poly(p-phenylene)

A design of novel synthetic polymers possessing metallic properties is studied on the basis of the one-dimensional tight-binding self consistent field-crystal orbital (SCF-CO) method. The idea presented here is to utilize crossing π bands of polyperylene (PP) and poly(p-phenylene) (PPP) by controlling the number of π electrons in the polymer skeletons. It is suggested that nitrogen-substituted PP, nitrogen-substituted PPP and boron-substituted PPP can be candidates for showing intrinsic metallic properties.     

Active flying-height control slider using MEMS thermal actuator

Today’s head/disk interface design has a wide flying height distribution due to manufacturing tolerances, environmental variations, and write-induced thermal protrusion. To reduce the magnetic spacing loss caused by these effects, we developed an active head slider with a nano-thermal actuator. The magnetic spacing of these sliders can be controlled in situ during drive operations. After simulating the heat transfer in the slider to obtain the thermal deformation of the air-bearing surface, we fabricated a thermal actuator using thin-film processing. An evaluation done using a read/write tester showed a linear reduction in the magnetic height as electric power was applied to the actuator. The actuator’s stroke was 2.5 nm per 50 mW with a time constant of 1 ms. There was no significant impact on the reliability of the read element.     

Fabrication of solid-state dye-sensitized TiO2 solar cells combined with polypyrrole

A solid-state solar cell was fabricated by photoelectrochemical polymerization of pyrrole on porous nanocrystalline TiO₂ electrode sensitized by the Grätzel dye, cis-di(thiocyanato)-N,N′-bis(2,2′-bipyridyl-4,4′-dicarboxylic acid)-ruthenium (II) dihydrate, [RuL₂(NCS)₂]), or a newly synthesized cis-Ru(dcb)₂(pmp)₂ (pmp=3-(pyrrole-1-ylmethyl)-pyridine). Polypyrrole successfully worked as a hole-transport layer with improvement of the cell characteristics when the TiO₂ cell with cis-Ru(dcb)₂(pmp)₂ was compared with the similarly fabricated cells using [RuL₂(NCS)₂]. The improvement by using Ru(dcb)₂(pmp)₂ can be explained as due to direct molecular wiring of the polymer-chain to the excited metal center of the complex.