Intercalation on Transition Metal Trichalcogenides via a Quasi-Amorphous Phase with 1D Order

Intercalation into 1D transition metal trichalcogenides (TMTs) in which fibers are bonded by a weak van der Waals force can be expected to create various intercalation compounds and develop unique physical properties according to the combination of the host materials and guest ions. However, structural changes via intercalation into 1D TMTs are not as simple as those in 2D transition metal dichalcogenides (TMDs) and are still not understood comprehensively. ZrTe₃: a typical compound with a 1D trigonal prismatic structure, belongs to TMTs. Herein, through the Ag introduction to ZrTe₃ via solid-state intercalation, a novel crystal phase with a 1D octahedral structure and a quasi-amorphous (QA) phase during the structural transition are discovered; the QA phase is a novel state of matter in which long-range order is lost while retaining 1D order. Based on the Ag concentration, the transport properties are flexibly modulated from superconductivity to semiconductivity. Density functional theory calculations indicate the attraction between Ag ions and the pair diffusion due to their attraction. Furthermore, judging the attraction or repulsion between guest ions predicts whether to induce a QA phase or simple lattice expansion like the intercalation into 2D TMDs.     

Flexible ultraviolet detector with robust ZnO nanoparticle nanoassemblies on catechol-functionalized polysiloxane nanofilms

As a result of the vast Young's moduli difference between an inorganic semiconducting channel and flexible substrates, flexible optoelectronic devices readily lose their functionality through material delamination and local fracturing, which lead to short-circuiting of devices. For this study, we synthesized a catechol-containing polysiloxane (CFPS) adhesive and applied it to ZnO nanoparticle (NP) assembly on plastic substrates for flexible UV detector applications. The 30 nm thick CFPS adhesive can anchor 70 nm thick ZnO NPs strongly through a coordination bond, thereby forming an ultra-stable ZnO NP channel layer. A peeling test of ZnO NP layer was conducted using transparent tape (Scotch®; 3 M Inc.). The ZnO NPs were firmly immobilized, reflecting the outstanding mechanical stability of CFPS adhesives. A UV detector also exhibited stable photo-response performance even after a thousand iterations of bending with 3 mm curvature radii. The result indicates the polycyclosiloxane-based flexible device as promising for wearable detector applications.     

Fabrication of fluorinated polymer nanosheets using the Langmuir–Blodgett technique: characterization of their surface properties and applications

This review describes the bottom‐up design of ultra‐thin fluorinated polymer films. Fluorinated polymer assemblies offer unique and application‐oriented properties strongly correlated with surface chemistry. We focus on our recent topic of research, fluorinated polymer nanosheets, which are ultra‐thin polymer films fabricated from amphiphilic fluorinated polyalkylacrylamides using the elegant Langmuir–Blodgett technique. These fluorinated polymer nanosheets have excellent hydrophobicity, extremely low surface energy and a low friction coefficient. Therefore, fluorinated polymer nanosheets are attractive nanomaterials for surface modification in terms of tailoring of wettability, frictional properties, adhesion and surface chemistry. The nanocoating technique using reactive fluorinated polymer nanosheets and surface modification of hard disks and microchannels are also reviewed. Copyright © 2010 Society of Chemical Industry     

In situ hydrogen plasma treatment for improved transport of (4 0 0) oriented polycrystalline silicon films

Polycrystalline silicon (poly-Si) films were deposited on glass by very high-frequency (100 MHz) plasma enhanced chemical vapor deposition from a gaseous mixture of SiF₄ and H₂ with small amounts of SiH₄. (2 2 0) oriented films prepared at small SiF₄/H₂ ratios (<30/40 sccm) showed intrinsic transport properties of poly-Si. However, the room temperature dark conductivity (σ_d) of the (4 0 0) oriented film was very high for intrinsic poly-Si, 7.2×10⁻⁴S/cm. This conductivity exhibited a T^−1/4 behavior, suggesting a high defect density at the grain boundaries. It was found that in situ hydrogen plasma treatment successfully produced (4 0 0) oriented poly-Si with a reasonably low σ_d of 4.5×10⁻⁷S/cm and a good photoconductivity of 1.3×10⁻⁴S/cm.     

Preparation of a new polyamide macromer having a vinylbenzyl group from bicyclic oxalactam and its radical copolymerization with styrene

Summary A new polyamide macromer having a vinylbenzyl end group (1), of which molecular weight was 3700–3800, was prepared by the anionic polymerization of bicyclic oxalactam (2) followed by the reaction with p-vinylbenzylamine. Its radical copolymerization with styrene was conducted to obtain a novel graft copolymer consisting of a polystyrene stock-chain and hydrophilic polyamide branches.     

A study of generator system selection for large wind turbine generator system

This paper focuses on selection of wind turbine generation systems that include generators, converters, and gears. We study three systems: a permanent magnet generator (PMG) system, a doubly‐fed generator (DFG) system, and a synchronous generator (SYG) system in terms of the system efficiencies and running costs. The system efficiencies and running costs are calculated by considering the relationship between wind power and wind conditions. According to these results, the one‐step gear PMG system is the best choice for a large wind turbine system. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 161(1): 51–57, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20506     

Study on intelligent humidity control materials: Water vapor adsorption properties of mesostructured silica derived from amorphous fumed silica

The intelligent humidity control materials were synthesized using fumed silica and quaternary alkylammonium surfactant (decyl-, dodecyl-, tetradecyl- and hexadecyl-trimethylammonium chlorides) as a liquid-crystal template under hydrothermal conditions. X-ray diffraction and transmission electron micrographs indicate that a homogeneous hexagonal structure of SiO2 was formed for those products. The mesostructured products had high B.E.T. surface areas between 960 and 1300 m2/g, with uniform mesopore diameters of 2–4nm. These physical quantities were controlled by varying the size of the organic template. Water vapor adsorption isotherms for these materials possess a sharp increase in adsorption when the relative water vapor pressure is at 40–60%. Over this range of pressures, the maximum amount of adsorbed water content is between 40 and 90%. These silicates have the potential to be effectively used as humidity control elements in construction materials.     

Polyethyleneimine/chitosan hexamer-mediated gene transfection into intestinal epithelial cell cultured in serum-containing medium

In search of an efficient nonviral vector, polyethyleneimine (PEI)-based vectors were examined. In general, the transfection efficiency of nonviral vectors is suppressed by serum. Here we show that PEI based vectors, particularly, the chitosan hexamer-PEI vector, could perform efficient gene transfection into intestinal epithelial cells (IEC-6) in the presence of serum. The conjugation order of the two polymers with a plasmid (first, chitosan hexamer; second, PEI) was found to be an important factor in enhancing transfection efficiency.     

Access concentration detection in click logs to improve mobile Web-IR

Effective ranking algorithms for mobile Web searches are being actively pursued. Due to the peculiar and troublesome properties of mobile contents such as scant text, few outward links, and few input keywords, conventional Web search techniques using bag-of-words ranking functions or link-based algorithms are not good enough for mobile Web searches. Our solution is to use click logs to clarify access-concentrated search results for each query and to utilize the titles and snippets to expand the queries. Many previous works regard the absolute click numbers as the degree of access concentration, but they are strongly biased such that higher-ranked search results are more easily clicked than lower-ranked ones. Therefore, it is considered that only higher-ranked search results are access-concentrated ones and that only terms extracted from them can be used to expand a query. In this paper, we introduce a new measure that is capable of estimating the degree of access concentration. This measure is used to precisely extract access concentration sites from many search results and to expand queries with terms extracted from them. We conducted an experiment using the click logs and data from an actual mobile Web search site. Results obtained show that our proposed method is a more effective way to boost the search precision than using other query expansion methods such as the top K search results or the most-often-clicked search results.