Relationships between fracture parameters and fracture surface roughness of brittle polymers

Fracture parameters such as crack velocity à, stress intensity factor K _d and a specific crack extension resistance R ^* were measured for Homalite-100, PMMA and epoxy in the course of fast crack propagation using a Cranz-Schardin type high speed camera. Fracture surface roughness was evaluated as a function of crack length a so that it could be correlated with the fracture parameters above. The results showed that none of those parameters could be uniquely related to . Instead, there was a good correlation between and a product R ^* à.     

NOx reduction behavior on alumina with discharging nonthermal plasma in simulated oxidizing exhaust gas

The NO_x reduction activity on γ‐alumina was significantly improved by discharging nonthermal plasma in a simulated oxidizing exhaust gas under conditions of a high space velocity. On the other hand, those on a Pt‐loaded catalyst and Cu‐ZSM‐5 could not be improved. The discharging nonthermal plasma converted NO to NO₂ and hydrocarbons to partial‐oxidized hydrocarbons, such as aldehydes, under the oxidizing conditions. From the relationship between the NO_x reduction activities and the properties of several alumina catalysts, it was found that the NO_x reduction activity was correlated with the number of acid sites on the alumina based on the NH₃ adsorption measurement. Therefore, it is concluded that the NO_x reduction occurred at the acid sites of the alumina, and the discharging nonthermal plasma improves the NO_x reduction activity by NO₂ formation and partial‐oxidation of hydrocarbons. These results suggest that a catalytic reaction assisted by the discharging nonthermal plasma could be a promising technology for NO_x reduction in lean‐burn and diesel exhaust gases even under the conditions of high space velocity. Copyright © 2006 Society of Chemical Industry     

Interlaminar fracture analysis of composite DCB specimens

Mode I interlaminar fracture was studies using double cantilever beam (DCB) specimens of unidirectional carbon fiber/epoxy composites. An improved analytical model was introduced to study the crack opening displacement (COD), compliance (C) and fracture toughness (G _I) as a function of the material stiffness () ahead of the crack front. The COD expression was derived and compared with the COD profiles near the crack tip measured by moiré interferometry. Results showed that the COD expression can predict all the important qualitative features of the measured COD profiles; also, the quantitative agreement at the loading point was very good. It was found that plays an important role in evaluating the values of COD, C and GI.     

The structure difference of proteins isolated on substrate with different techniques as studied by the atomic force microscope

The height and width of proteins deposited on mica substrates were measured from cross sections of their atomic force microscope (AFM) images. The tapping mode AFM gave very stable and reproducible images for high molecular weight proteins. The following results were obtained: (1) The thickness of mono-, bi-, and trilayered purple membranes was 5.3, 10.4, and 16.0 nm, respectively. The calibration curve of z range of AFM based on the above data was linear. The deviation of the calibration curve at the origin was < 0.6 nm. (2) The height of slow form α-2-macroglobulin (α2M) molecule changed depending on sampling methods. When the protein was freeze-dried on a mica substrate prewetted with water, α2M gave the highest value for its height. The fact that freeze-drying, especially after prewetting of the substrate, was effective to prevent flattening of the molecule suggested that sample deposition must be as gentle as possible to keep the original height of the molecules. (3) Furthermore, we compared differences of height and width between α2M and myosin filament. The result suggested that α2M had a disk-like rather than a spherical form. Large proteins such as α2M are still difficult to crystallize for x-ray analysis, and we tested the AFM method for the study of minute height differences of such proteins.     

Preparation and characterization of gelatin sponge millispheres from air-in-water-in-oil-type emulsions

A novel method for the preparation of gelatin sponge millispheres (GSMs) for biomaterials such as embolic agents and cell scaffolds was developed using an air-in-water-in-oil-type emulsion. The droplets, consisting of a foamy gelatin suspension in caprylic triglyceride, were gelled and rinsed with isopropanol. Sonication and depressurization were used during the rinsing process to create interconnected pores. GSMs cross-links created over 4 h at 155°C without any agent were insoluble and had short and long diameters of 1.1 ± 0.2 mm and 1.3 ± 0.2 mm, respectively. The residual isopropanol and caprylic triglyceride were <0.05% (w/w) and <1% (w/w) respectively. The level of bacterial endotoxins in the extracts was below 0.025 EU/ml, and no bacterial or fungal growth was found during sterility testing. The GSMs produced using this method were considered to meet the basic requirements of embolic agents.     

A long-term degradation study of power generation characteristics of anode-supported solid oxide fuel cells using LaNi(Fe)O3 electrode

The long-term operation of an anode-supported solid oxide fuel cell was examined to study the degradation factor. The cell was constructed using LaNi_0.6Fe_0.4O₃ (LNF), alumina-doped scandia stabilized zirconia (SASZ), and NiO-SASZ as the cathode, electrolyte, and anode respectively. The cell had Pt current collectors and was operated for 6500 h. The test was carried out at 1073 K with a constant load of 0.4 A cm⁻² and included thermal cycling. The cell voltage degradation rate was below 0.86%/1000 h when the cell was operated for up to 5200 h. Changes in the resistance of the cells during the experiments were analyzed by impedance spectroscopy. The cathode polarization resistance and ohmic resistance increased with time. The elements (Si and B) contained in the water condensed from the cathode exhaust gas were identified using inductively coupled plasma (ICP).     

Occurrence of tetrodotoxin and paralytic shellfish poisons in a gastropod implicated in food poisoning in southern Taiwan

The toxicity of the gastropod Nassarius papillosus implicated in a food paralytic poisoning incident in Liuchiu Island, Taiwan, in October 2005 is reported. The symptoms of a victim (67 years old) were featured by general paresthesia, paralysis of phalanges and extremities, paralysis, coma, and aphasia. The remaining specimens of shell were assayed for toxicity. The range of specimen toxicity was found to be 63-474 mouse units (MU) per specimen for N. papillosus by a tetrodotoxin (TTX) bioassay. The mean (SD) toxicity of the digestive gland and other portions were 296 ± 120 and 382 ± 156 MU in N. papillosus. The toxin was partially purified from the acidic methanol extract of the gastropod by using a C18 solid-phase extraction column. The eluate was then filtered through a 3000 MW cut-off ultrafree microcentrifuge filter. It was shown that the toxin purified from gastropods analysed by high-performance liquid chromatography and liquid chromatography/mass spectrometry contained TTX 42-60 µg g^-1 (about 90%), whereas along with minor paralytic shellfish poisons (PSP) it was 3-6 µg g^-1 (about 10%).     

Rational choice of bioactive conformations through use of conformation analysis and 3-way partial least squares modeling

Comparative molecular field analysis (CoMFA) has become widely used in three-dimensional (3D) QSAR studies. Although CoMFA has been of general use, there are some critical problems in the proper application. A major problem of CoMFA, including most other 3D QSAR methodologies, is that the results are dependent on the chosen bioactive conformations and the corresponding alignment rules of molecules. Recently, we have proposed a novel method with a 3-way PLS formulation for solving the conformation/alignment problem in 3D QSAR studies [K. Hasegawa, M. Arakawa, K. Funatsu, Chemom. Intell. Lab. Syst., 47 (1999) 33–40]. The purpose of the present study is to demonstrate the general utility of our approach by applying to a real CoMFA data set. The data set of Protein-Tyrosine Kinase (PTK) inhibitors was used as a test sample. The possible 3D conformations of all molecules were generated by conformational analysis and they were characterized by field variables of CoMFA. To each unique conformation of the most active compound, one sample-variable sheet comprising of the most similar conformations was defined. The 3-way arrays for 3-way PLS analysis were created by collecting all sample-variable sheets. From the regression coefficient values of the 3-way PLS model, conformations largely contributing to inhibitory activity were selected and the resulting final CoMFA model could give the reasonable 3D coefficient contour maps.     

Multi-shot flash lamp annealing method for electroless-plated Ni-P film on UV-surface-modified ABS

The multi-shot flash lamp annealing (FLA) method as a rapid annealing technique was developed for an electroless-plated Ni-P film on UV-surface-modified acrylonitrile–butadiene-styrene (ABS) in place of the conventional annealing method. The new multi-shot FLA method continuously irradiates a Xe flash discharge with low irradiance (<1?J?cm^–2) with a frequency of 3?Hz. An adhesion strength between the electroless Ni-P film and ABS of more than 1.2?kN?m^–1 was achieved in a short time of approximately 30?s; this adhesion strength was larger than that obtained in the conventional method of 1?h duration. The etching effect of the FLA method was assessed by a study of the surface morphologies of the Ni-P films. XRD spectra of the Ni-P films showed an improvement in the crystallinity of the films. Considering surface elemental analyses of the peeled Ni-P-film/ABS, a cohesive failure, which implies high adhesion, was observed in the ABS. The proposed FLA method is expected to efficiently improve the adhesion and significantly reduce the annealing time in the electroless plating process.     

Persulfate-induced photochemical decomposition of a fluorotelomer unsaturated carboxylic acid in water

The persulfate (S(2)O(8)(2-))-induced photochemical decomposition of C(3)F(7)CF=CHCOOH in water was investigated to develop a method to neutralize stationary sources of fluorotelomer unsaturated carboxylic acids (FTUCAs), which have recently been detected in the environment, and are considered to be more toxic than the environmentally persistent perfluorocarboxylic acids (PFCAs). Photolysis of S(2)O(8)(2-) produced highly oxidative sulfate radical anions (SO(4)(-)), which efficiently decomposed C(3)F(7)CF=CHCOOH to F(-) and CO(2) via C(3)F(7)COOH. With an initial S(2)O(8)(2-) concentration of 12.5mM and irradiation from a 200-W xenon-mercury lamp, C(3)F(7)CF=CHCOOH at a concentration of 680muM was completely decomposed within 5min. When 8.00mM S(2)O(8)(2-) was used, the initial rate of C(3)F(7)CF=CHCOOH decomposition induced by 254-nm light irradiation was 45 times as high as that with photolysis alone. The apparent quantum yield for the C(3)F(7)CF=CHCOOH decomposition with 6.25mM S(2)O(8)(2-) and 254-nm light was 2.4, indicating that virtually all SO(4)(-) anions produced by the photolysis of S(2)O(8)(2-) contribute to the decomposition of C(3)F(7)CF=CHCOOH.