Growth and microstructures of sputtered ferroelectric PbTiO3 thin films

Abstract

PbTiO₃ thin films, 5–200 nm in thickness, were epitaxially growth on miscut (001) SrTiO₃ substrates by planar magnetron sputtering for understanding of film growth mechanism and their ferroelectricity. The surface of the miscut substrates with miscut angle of 1.7 degree contains periodic step lines and terraces; the step height is 0.4 nm and terrace width is 14 nm. The surface structures of PbTiO₃ films comprised periodic striped patterns which was reflected in the initial surface of the substrate. It was found that under a stoichiometric film composition the film growth was governed by Frank-van der Merwe type and resultant epitaxial films showed extremely smooth surface. Deposition on a miscut substrate under a stoichiometric condition is essential to making the uniform ferroelectric thin films.     

Evaluation of the Correlation between Porphyrin Accumulation in Cancer Cells and Functional Porphyrin Positions of the Phenyl Group

Porphyrin selectively shows tumour accumulation and has attracted attention as a carrier molecule for drug delivery systems (DDS). Porphyrin has two functional sites termed the meso- and β-positions. In previous work, meso-porphyrin derivatives with an alkyl group were found to exhibit greater accumulation in human breast cancer cells (MCF-7). To identify the correlation between porphyrin accumulation and functional porphyrin positions of other functional groups, the accumulation of porphyrin derivatives with a phenyl group was investigated. The β-porphyrin derivative with a phenyl group showed higher accumulation in MCF-7 cells and greater affinity for albumin than the meso-porphyrin derivative. The results of density functional theory (DFT) calculations suggest that the β-porphyrin derivative with a phenyl group had higher planarity across the total structure than the meso-porphyrin derivative. It was concluded that the greater planarity of the β-porphyrin derivative with a phenyl group might lead to superior MCF-7 cell accumulation.     

High sensitive immunoassay for endocrine disrupting chemicals using antibody immobilized microcapillary bundle structure

We proposed and fabricated a new chemical reactor with a vertical fluid flow operation for the wide biochemical applications. For rapid and high-yield reaction between reagents with large quantity, the filters, which possess 2,100 cylindrical through-bores were fabricated by deep X-ray lithography using synchrotron radiation. First, we tried the application of the fabricated vertical reactor to a sandwich enzyme-linked immunosorbent assay for the analysis of mouse immunoglobulin and nonylphenol using ultra violet absorption spectroscopy. We also confirmed the possibility of the analysis methods for competitive enzyme-linked immunosorbent assay of an endocrine disrupter, nonylphenol in a series of vertical fluidic operation. This sensitivity was one order higher than the sensitivity obtained by ordinary enzyme-linked immunosorbent assay using 96-wells microtiter plate and the same anti-NP-antibody.     

Harnessing Topology and Stereochemistry of Glycidylamine-Derived Lipid Nanoparticles for in Vivo mRNA Delivery to Immune Cells in Spleen and Their Application for Cancer Vaccination

mRNA lipid nanoparticles (LNPs) have reached an inflection point and are now paving the way for a new wave of precision therapies. The design of nonhepatocyte RNA delivery systems without targeting ligands, however, remains a challenge. It is reported that the development of ligand-free glycidylamine (GA) derivatives containing LNPs (GA-LNPs) that preferentially deliver mRNA to immune cells in the spleen. Notably, it is demonstrated that the stereochemistry of GA-lipids has a significant impact on their self-assembly and in vitro and in vivo RNA delivery efficiency and tropism. This impact is dependent on the monomeric structure of GA and number of stereogenic centers. Furthermore, the nonlinear topology of GA lipid derivatives induced a sevenfold improvement in mRNA delivery efficiency. The top-performing estriol-GA05-30 LNPs elicited strong antitumor activity in a therapeutic and prophylactic cancer model and are well tolerated in mice. These results highlight the significance of the chemistry of ionizable lipids for extrahepatic RNA delivery and indicated a promising direction for the development of next-generation mRNA immunotherapies.     

Probing a two-step channel formation process in injection-type pentacene field-effect transistors by time-resolved electric-field-induced optical second-harmonic generation measurement

By using time-resolved electric-field-induced optical second-harmonic generation measurement, we studied carrier motion in pentacene field-effect transistors (FETs) with poly-4-vinylphenol (PVP) and with polyimide (PI) gate-insulator whose active layers were depleted by pre-biasing. Upon removal of the pre-biasing, channel formation proceeded as a two-step process in FETs with PVP gate-insulator and a conduction channel was formed eventually. On the other hand, no conduction channel was formed in FETs with PI gate-insulator but two-step carrier propagation was observed in a similar way. Results showed that a local electric field induced on the gate-insulator surface gives a significant effect on the carrier injection and the following carrier transport.     

Development of externally pressurized small-size conical-shaped gas bearings for micro rotary machines

We have developed externally pressurized small-size conical shaped gas bearings for micro rotary machines such as gas blowers, compressors, and medical devices. The bearings are lightweight and enable machines and devices to be downsized by reducing the number of parts, since the journal and thrust loads can be supported by a pair of bearings. The conical bearings (diameters 8 mm and 10 mm) were designed and the manufacturing techniques were considered. The bearing type is a double-row inherent orifice bearing with four feed holes per row. The shape accuracy of the manufactured bearings is within the design limits, being less than 0.005 mm in both roundness and cylindricity. The surface roughness (arithmetic average roughness) of the parts is 0.0002 mm. The static characteristics were calculated and validated by testing on manufactured bearings. Comparative agreement was obtained between the measured and designed values. The proposed calculation method presents as a relatively simple approach for predicting the bearing characteristics. The test rotor exceeded 350 Hz (21,000 rpm) in the rotational test, and whirl vibration was absent. During testing, the maximum rotor vibration amplitude was 0.0125 mm (corresponding to an eccentricity ratio of 0.89).     

Compatibility with Jet A-1 of a GCL Subjected to Freeze–Thaw Cycles

Needle-punched geosynthetic clay liner (GCL) specimens subjected to 0, 5, and 12 freeze–thaw cycles in the laboratory, and GCL specimens recovered from a composite barrier wall in the Canadian Arctic after 1 and 3 years were examined to assess the hydraulic conductivity/permeability with respect to both deionized deaired water and Jet A-l. The GCL specimens recovered from the field after 3 years had a hydraulic conductivity with respect to water that was approximately 30% less than that of the GCL specimens subjected to 12 initial freeze–thaw cycles in the laboratory, suggesting that the laboratory conditions are more severe than field conditions. The combined effects of both the freeze–thaw cycles and Jet A-l permeation increased the permeability. This increase is attributed to the creation of macropores in the GCL due to freezing and to an expansion of free-pore space due to contraction of the double layer caused by permeation of Jet A-l. Although there was an increase in permeability due to the combined effect of freeze–thaw and permeation by Jet A-l, the effect was relatively small and the results suggest that the GCL continued to exhibit good performance as a hydraulic barrier when subject to extreme climatic conditions and hydrocarbons both in the laboratory and in the field.     

Interfaces between geothermal brine-induced scales and SiC-FILLED polymer LININGS

Silicon carbide (SiC) grit-filled polymeric materials with high thermal conductivity can be used to line carbon-steel heat-exchanger tubes in geothermal power plants at moderate temperatures and to improve resistance to corrosion. The susceptibility of ester groups within the polymers to a reaction with Ba, which is among the chemical ingredients of some geothermal brines, is a critical issue for this lining material because of the formation of Ba-complexed carboxylate hydrolysates. Such hydrolysates promote the deposition of brine-induced scales.     

Physical and mechanical properties of municipal solid waste incineration residues with cement and coal fly ash using X-ray Computed Tomography scanners

A significant volume of Municipal Solid Waste incineration bottom ash and fly ash (i.e., incineration residues) are commonly disposed as landfill. Meanwhile, reclamation of landfill sites to create a new land space after their closure becomes an important goal in the current fewer and fewer land availability scenario in many narrow countries. The objective of this study is to reclaim incineration residue materials in the landfill site by using cement and coal fly ash as stabilizers aiming at performing quality check as new developed materials before future construction. Indeed, physical and mechanical properties of these new materials should be initially examined at the micro scale, which is the primary fundamental for construction at larger scale. This research examines quantitative influences of using the combination of cement and coal fly ash at different ratio on the internal structure and ability of strength enhancement of incineration residues when suffering from loading. Couple of industrial and micro-focus X-ray computed tomography (CT) scanners combined with an image analysis technique were utilized to characterize and visualize the behavior and internal structure of the incineration residues-cement-coal fly ash mixture under the series of unconfined compression test and curing period effect. Nine types of cement solidified incineration residues in term of different curing period (i.e., 7, 14, 28 days) and coal fly ash addition content (i.e., 0%, 9%, 18%) were scanned before and after unconfined compression tests. It was shown that incineration residues solidified by cement and coal fly ash showed an increase in compression strength and deformation modulus with curing time and coal fly ash content. Three-dimension computed tomography images observation and analysis confirmed that solidified incineration residues including incineration bottom and fly ash as well as cement and coal fly ash have the deliquescent materials. Then, it was studied that stabilized parts play a more important role than spatial void distribution in increment or reduction of compression strength.