Development of optical coatings for 157-nm lithography. II. Reflectance,absorption, and scatter measurement

The total loss that can be suffered by an antireflection (AR) coating consists of reflectance loss, absorption loss, and scatter loss. To separate these losses we developed a calorimetric absorption measurement apparatus and an ellipsoidal Coblentz hemisphere based scatterometer for 157-nm optics. Reflectance, absorption, and scatter of AR coatings were measured with these apparatuses. The AR coating samples were supplied by Japanese vendors. Each AR coating as supplied was coated with the vendor's coating design by that vendor's coating process. Our measurement apparatuses, methods, and results for these AR coatings are presented here.     

New method for obtaining the distillation curves of petroleum products and coal-derived liquids using a small amount of sample

Based on thermogravimetric principles a new distillation method for petroleum products and coal-derived liquids has been developed. The boiling point distributions of five petroleum fractions (kerosene; 128–228 °C; light gas oil, 178–298 °C; middle gas oil, 200–360 °C; vacuum gas oil, 268–565 °C; and high vacuum gas oil, 305–604 °C) and one highly aromatic coal-tar fraction (wash oil, 180–310 °C) were obtained. The results are in good agreement with those obtained by standard (ASTM) distillation methods. The amount of sample required is very small (≈10 mg) and can be solid or liquid. The experiments at normal pressure were carried out using a specially designed sample holder made of quartz. In the case of high-boiling-point fractions (distillation under reduced pressure) a normal sample holder can be used. The results are automatically recorded as temperature versus weight loss.     

Solubility increase of coals by the reaction with alcohol — elucidation of reaction mechanism using model compounds

The reaction mechanism of coal-ethanol reaction was examined using model compounds: phenol, benzylphenylether, diphenylmethane and anthracene. The main reaction for these compounds was the splitting of ether bonds, ethylation of benzene nucleii, hydrogenation of aromatic nucleii and the splitting of methylene linkages. The most important reactions were the first two types. The splitting of ether linkages would reduce the molecular weight of coal and ethylation of aromatic rings would be favorable to the easy dissolution of coal in solvents.     

pH-responsive Multi-PEGylated dual cationic nanoparticles enable charge modulations for safe gene delivery

In gene therapy, the cytotoxicity of many polycations is undesirable and has been attributed to nonspecific membrane destabilizing effects and intracellular polyplex-mediated toxicity. To help prolong the pharmacokinetic profile of nonviral vehicles for gene delivery, the cationic surface charge of current systems is typically shielded through the conjugation of polyethylene glycol (PEG) chains to the particle surface. However, the design of an intelligent polycation with environment-sensing charge modulations is essential to minimize cytotoxicity and enhance gene expression. We have designed a novel di-cationic block copolymer, poly(aspartate-hydrazide)-block-poly(L-lysine), capable of pH-mediated endosomal membrane disruption based on charge interactions, which has negligible toxicity elsewhere to the cell. The poly(L-lysine) segment, with a high pK(a) value of approximately 9.4, preferentially forms a poly-ion complex with the negative phosphate groups of pDNA, whereas the pH-responsive poly(aspartate-hydrazide) segment, with the comparatively lower pK(a) approximately 5.0, is characterized by a substantial fraction of unprotonated amino groups at physiological pH. As a consequence, complexation between such a polymer and pDNA leads to the formation of a two-layered nanoparticle. In particular, the nanoparticle possesses an unprotonated pH-responsive segment to serve as both a scaffold for acid-labile linkages of various moieties such as aldehyde-PEG and to transition from neutral to charged for disrupting endosomal membranes, and safely enhancing gene expression. Our system supports an endosomal escape mechanism based on charge interactions rather than the proton-sponge effect, and may be an important step towards engineering new classes of intelligent nonviral vectors.     

Precision control of radical polymerization via transition metal catalysis: from dormant species to designed catalysts for precision functional polymers

In the past decade, living radical polymerization has provided one of the most versatile methods to precisely construct designed polymer architectures with complexity and polar functionality. This process takes advantage of carbon-radical intermediates, which tolerate a variety of functional groups in monomers and reaction media. "Transition metal-catalyzed living radical polymerization", one of these living systems, has widely been employed for precision polymer synthesis. Not only can this process produce well-defined functional polymers, but it can also generate hybrids or conjugates with other (often biological) materials. Metal-catalyzed systems retain the advantages of conventional radical polymerization but distinguish themselves through a catalytic reversible halogen exchange equilibrium: the growing radical exists alongside a dormant speciesa covalent precursor capped with a terminal halogen from an initiator. The catalyst dictates the selectivity, exchange rate, and control over the polymerization. This Account provides an updated overview of our group's efforts in transition metal-catalyzed living radical polymerization with specific emphasis on the design of metal catalysts and the resulting precision polymer syntheses. With increasing use of the living processes as convenient tools for materials synthesis, researchers are currently seeking more active and versatile metal catalysts that are tolerant to functional groups. Such catalysts would enable a wider range of applications and target products, would have low metal content, could be readily removed from products, and would allow recycling. Since we first developed the "transition metal-catalyzed living radical polymerization" with RuCl 2(PPh 3) 3, FeCl 2(PPh 3) 2, and NiBr 2(PPh 3) 2, we have strived to systematically design metal catalysts to meet these new demands. For example, we have enhanced catalytic activity and control through several modifications: electron-donating or resonance-enhancing groups, moderate bulkiness, heterochelation via a ligand, and halogen-donor additives. For some catalysts, the use of amphiphilic and polymeric ligands allow efficient recovery of catalysts and convenient use in aqueous media. We have also used ligand design (phosphines) and other methods to improve the thermal stability of iron- and nickel-based catalysts and their tolerance to functional groups.     

Observation of lightning at 500‐kV transmission lines (part 1)

We investigated the phenomenon of lightning strokes on 500‐kV transmission lines from 1984 to 1993. The investigation covered the recording of lightning paths by still cameras and measurements of lightning current at the lower part of transmission tower on 31 towers, over a 12.7‐km‐long section of the transmission line. We also observed lightning on an isolated tower at a nuclear power station. In the course of lightning observations spanning a 10‐year period, we have confirmed the suitability of the lightning protection design on transmission lines. The distribution of lightning incidence angle (θ) expressed in terms of (cos^mθ) was characterized by exponent m = 2 for the three‐dimensional observations and m = 3.5 for the two‐dimensional observations. No cases of shielding failure on 500‐kV transmission lines were observed. The ratio of lightning current at the top of the isolated tower to the lower part was about 11 to 1. In addition, the lightning current waveform at the top of the isolated tower was similar to that at the lower part. © 1999 Scripta Technica, Electr Eng Jpn, 130(2): 59–67, 2000     

Fe2O3-filled carbon nanotubes as a negative electrode for an Fe–air battery

Fe₂O₃-filled carbon nanotube material was prepared by filling carbon nanotubes (CNTs) with iron nitrate and then heating in an argon flow. The morphology and structure of this material were investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM) coupled with X-ray energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) measurements. The morphology, particle size and amount of iron oxide that filled CNTs depended on the amount of iron nitrate precursor. When Fe:C = 1:17 wt%, almost all of the iron oxide particles resided inside CNTs and their particle size was smaller than that at Fe:C = 1:8 wt%. The electrochemical properties of this material were investigated using cyclic voltammetry (CV) and galvanostatic cycling.     

棉织物的无氯光化学漂白

描述了日本茨城的日本国家高级产业科学技术研究院(AIST)开发的一种有效的光化学棉织物漂白工艺.这种工艺在室温下采用无氯试剂的水溶液.介绍了光化学漂白样机的构成和效率.     

Temporal and Spatial Variations in N2O Emissions from a Chinese Cabbage Field as a Function of Type of Fertilizer and Application

We conducted a field experiment in an Andosol near Tsukuba (Japan) to study the effects of the type of nitrogen fertilizer on nitrous oxide (N₂O) emissions and on nitrogen uptake by Chinese cabbage (Brassica campestris L.). We used four treatments: fertilizer containing no nitrogen (CONT), broadcast application of urea (BR-U), band application of urea (B-U), and band application of controlled-release urea (B-CU). The application rate was 250 kg N ha⁻¹, a conventional rate in the region. We measured N₂O flux two or three times a week during the 82-day growth period, then divided the cumulative emissions into three stages: early (28 days), middle (27 days), and late (27 days). The temporal variation in N₂O emissions differed among the treatments. Broadcast urea application produced 70% of N₂O emissions during the early stage. N₂O emissions increased with increasing cabbage growth in the CONT treatment, indicating that plant growth accompanied by increasing root biomass could stimulate N₂O emissions from unfertilized soil. There were no differences in the patterns of temporal variation in N₂O flux between the two band applications (B-U and B-CU); N₂O emissions in the early and middle stages were 46 and 42%, respectively, for B-U, vs. 41 and 40% for B-CU. However, the overall N₂O emission was reduced by 40.5% in the B-CU treatment compared with the B-U treatment. N₂O emissions from the soils within fertilized bands were dramatically higher than those between the fertilized bands, and this trend continued until harvesting.