The use of a phase adjuster (PA) has been proposed to improve the cooling effect of a loop-tube-type thermoacoustic cooling system. A PA is a device for increasing the particle velocity of sound by narrowing a part of the loop tube. In this experiment, we present a discussion of the efficiency of heat-to-sound energy conversion in a loop-tube-type thermoacoustic prime mover, particularly emphasizing on the inner diameter change of PA. It is found that the sound pressure is higher for larger inner diameter; the particle velocity is higher for larger inner diameter and the phase difference between the sound pressure and the particle velocity is bigger for larger inner diameter. It is also found that sound intensity is different according to the inner diameter, and that it is higher for larger inner diameter. Results obtained confirm that PA improves the efficiency of heat-to-sound energy conversion in the loop-tube-type thermoacoustic prime mover, and that the efficiency depends on the inner diameter of PA.

Functionalization of nanoparticles (NPs) with targeting moieties has a high potential to advance precision nanomedicine. However, the targeting moieties on a NP surface are known to be masked by a protein corona in biofluids, lowering the targeting efficiency. Although it has been demonstrated at the cellular level, little is known about the influence of the protein corona on the subcellular targeting. Herein, we adopted triphenylphosphonium (TPP) as a mitochondrial targeting moiety and investigated the effects of protein coronas from fetal bovine serum and human plasma on its targeting ability and cytotoxicity. Specifically, we introduced TPP in low (l) and high (h) densities on the surface of nanodiamond (ND) functionalized with polyglycerol (PG). Despite the "corona-free" PG interface, we found that the TPP moiety attracted proteins to form a corona layer with clear linearity between the TPP density and the protein amount. By performing investigations on human cervix epithelium (HeLa) and human lung epithelial carcinoma (A549) cells, we further demonstrated that (1) the protein corona alleviated the cytotoxicity of both ND-PG-TPP-l and -h, (2) a smaller amount of proteins on the surface of ND-PG-TPP-l did not affect its mitochondrial targeting ability, and (3) a larger amount of proteins on the surface of ND-PG-TPP-h diminished its targeting specificity by restricting the NDs inside the endosome and lysosome compartments. Our findings will provide in-depth insights into the design of NPs with active targeting moiety for more precise and safer delivery at the subcellular level.

Detonation nanodiamonds (DNDs) have attracted considerable attention, in particular, in the field of nanomedicine due to their biocompatibility as well as various functionalities imparted by surface modification. Meanwhile, boron neutron capture therapy (BNCT) is an advanced cancer treatment utilizing nuclear fission reaction of 10B upon neutron irradiation. Recently, quite a few boron-containing nanoparticles have been investigated to deliver 10B atoms into cancer tissue selectively and retentively. In this study, we explored boronic acid functionalized DNDs as an anticancer agent for BNCT. Phenylboronic acid (PBA) moiety was introduced to polyglycerol (PG) modified DNDs (DND-PG) through multistep organic transformation, giving percent order of boron atoms. The process is scalable and reliable by simple covalent chemistry and the resulting product is well dispersed, and stable chemically and physically under physiological conditions. In the in vivo experiments, the resulting material was accumulated in the tumor to exert BNCT efficacy upon neutron irradiation. These results demonstrate that the PBA functionalized DNDs are a promising candidate as an anticancer nanodrug for BNCT.

The efficiency of dye-sensitized solar cells (DSSCs) using Ru complex dyes and Co complex redox couples has been increased with a strategy to prevent charge recombination via the addition of bulky or lengthy peripheral units to the dyes. However, despite the efforts, most of the DSSCs are still suffering from nonunity quantum efficiency and fast recombination. We examine the effect of SCN ligand, which has been used for many Ru complex dyes and could attract positively charged Co complexes. We find that replacing the ligands with 2,6-bis(2'-(4'-trifluoromethyl)pyrazolyl)pyridine increases the quantum efficiency and electron lifetime. With the combination of the replacement of SCN ligands and the addition of bulky moiety, ∼80% external quantum efficiency is achieved. These suggest that not only the addition of a blocking effect but also the reduction of electrostatic and dispersion forces between dyes and Co complexes are essential to control the charge separation and recombination processes.