Dendritic cells (DCs) are able in tissue culture to phagocytose and present antigens derived from infected, malignant, and allogeneic cells. Here we show directly that DCs in situ take up these types of cells after fluorescent labeling with carboxyfluorescein succinimidyl ester (CFSE) and injection into mice. The injected cells include syngeneic splenocytes and tumor cell lines, induced to undergo apoptosis ex vivo by exposure to osmotic shock, and allogeneic B cells killed by NK cells in situ. The CFSE-labeled cells in each case are actively endocytosed by DCs in vivo, but only the CD8+ subset. After uptake, all of the phagocytic CD8+ DCs can form major histocompatibility complex class II–peptide complexes, as detected with a monoclonal antibody specific for these complexes. The CD8+ DCs also selectively present cell-associated antigens to both CD4+ and CD8+ T cells. Similar events take place with cultured DCs; CD8+ DCs again selectively take up and present dying cells. In contrast, both CD8+ and CD8− DCs phagocytose latex particles in culture, and both DC subsets present soluble ovalbumin captured in vivo. Therefore CD8+ DCs are specialized to capture dying cells, and this helps to explain their selective ability to cross present cellular antigens to both CD4+ and CD8+ T cells.

Photoplethysmography (PPG) technology has been used to develop small, wearable, pulse rate sensors. These devices, consisting of infrared light-emitting diodes (LEDs) and photodetectors, offer a simple, reliable, low-cost means of monitoring the pulse rate noninvasively. Recent advances in optical technology have facilitated the use of high-intensity green LEDs for PPG, increasing the adoption of this measurement technique. In this review, we briefly present the history of PPG and recent developments in wearable pulse rate sensors with green LEDs. The application of wearable pulse rate monitors is discussed.

Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) are shown to be globally distributed, environmentally persistent, and bioaccumulative. Although the toxicities of these compounds were reported, the cleanup procedure from the environment is not developed because of their inertness. In this report the sonochemical degradations of PFOS and PFOA to the products through the fission of the perfluorocarbon chains were observed and the half-life times of the PFOS and PFOA degradations under an argon atmosphere determined to be 43 and 22 min, respectively. The shortening of perfluorocarbon chain of PFOS and PFOA leads to the lowering of the toxicity in view of the decrease of the persistence, and the technique would contribute to the remediation of the environmental pollution by these compounds.

This is a report regarding the preparation of nanosized gold/palladium bimetallic particles utilizing a cavitation phenomenon induced by irradiation of high-intensity ultrasound in an aqueous solution of gold(III) and palladium(II) ions. The particles are found to be composed of gold-core and palladium-shell by a transmission electron microscopic and nanoarea energy-dispersive X-ray spectroscopic analyses. Sodium dodecyl sulfate added to the sample solution is found to be a stabilizer for the nanoparticles generated as well as an important source of reducing species for noble metal ions. The thickness of a palladium shell and the size of a gold core seem to depend on the ratio of the concentrations of noble metal ions. The morphological differences in the sonochemical and radiochemical products suggest that the formation of a core-shell structure can be affected by the physical effects of ultrasound, such as effective stirring, microjet stream, or shock wave during the collapse of a cavitation bubble. Bimetallic nanoparticles show higher activities for the hydrogenation of 4-pentenoic acid than for those of the mixtures of monometallic nanoparticles with a corresponding gold/ palladium ratio. When the gold/palladium ratio is 1:4, the activity of the bimetallic particles is about three times higher than that of palladium monometallic nanoparticles prepared under the same conditions.

The oxidation of nitrite by dissolved oxygen to form nitrate is known to be accelerated ca. 105 times by the freezing of the aqueous solution. Here we report a detailed study on the acceleration mechanism of the above-mentioned oxidation. The reaction was studied at pH values between 3.0 and 5.6 at various freezing rates, by different freezing methods, and with and without additional salts. The effect of freezing which induced concentration (freeze concentration) of reactants into the unfrozen bulk solution was too small to explain the acceleration factor of ca. 105. Nitrate formations were completely prevented by addition of salts, such as NaCl and KCl, which make the freezing potential of ice negative, while the reaction was not affected by addition of salts, such as Na2SO4 and NH4Cl, which make the freezing potential of ice positive. When a sample solution was frozen in such a way as to form a single crystal of ice, most nitrite was exclusively liberated from the ice to the gas phase. This observation suggests the importance of ice in the polycrystalline form to retain nitrite during freezing. When freezing begins, grains of crystalline ice begin to grow. The solutes are rejected from the ice and concentrated in the interfacial water layer by assistance of the electrostatic force generated by the freezing potential. At a certain stage of freezing, the water layer is completely confined by the walls of some ice grains. Protons move from the ice phase to the unfrozen solution surrounded by the ice walls to neutralize the electric potential generated, and thus the pH of the unfrozen solution decreases. As a result, the reactant species, HNO2, increased more in the unfrozen solution. After this stage, the concentrations of the reactants in the unfrozen solution abruptly increase resulting in the acceleration of the rate of formation of nitrate. On the basis of the above mechanism, the concentration factor for nitrite was calculated as 2.4 × 103. The validity of this mechanism is further discussed.