Search

Effect-directed analysis was used to identify previously unidentified aryl hydrocarbon receptor (AhR) agonists in sediments collected from a highly industrialized area of Ulsan Bay, Korea. The specific objectives were to (i) investigate potent fractions of sediment extracts using the H4IIE-lucbioassay, (ii) determine the concentrations of known AhR agonists (polycyclic aromatic hydrocarbons (PAHs) and styrene oligomers (SOs)), (iii) identify previously unreported AhR agonists in fractions by use of GC-QTOFMS, and (iv) evaluate contributions of individual compounds to overall AhR-mediated potencies, found primarily in fractions containing aromatics with log Kow5–8. Greater concentrations of PAHs and SOs were also found in those fractions. On the basis of GC-QTOFMS and GC-MSD analyses, 16 candidates for AhR agonists were identified in extracts of sediments. Of these, seven compounds, including 1-methylchrysene, benzo[j]fluoranthene, 3-methylchrysene, 5-methylbenz[a]anthracene, 11H-benzo[b]fluorene, benzo[b]naphtho[2,3-d]furan, and benzo[b]naphtho[2,1-d]thiophene, exhibited significant AhR activity. Relative potency values of newly identified AhR agonists were found to be greater than or comparable to that of benzo[a]pyrene (BaP). The potency balance analysis showed that newly identified AhR agonists explained 0.07–16% of bioassay-derived BaP-EQs. These chemicals were widely distributed in industrial sediments; thus, it is of immediate importance to conduct studies on sources and potential effects of those chemicals.

Abstract: Recolonization of benthic fauna in defaunated sediment contaminated with octylphenol (OP) has been investigated by the use ofin situ microcosm exposure study. Trays with defaunated sediment (control) and those treated with five OP concentrations (0.59, 5.4, 7.6, 66, and 660 μg g−1, sediment dry weight (DW)) were exposed at the subtidal (ca. 10 m), in the southern coast of Korea, over two months. The initial response (after one-month exposure) of macrozoobenthos at the trays of control and three lower OP (0.59–7.6 μg g−1 DW) showed rapid colonization of macrozoobenthos with high diversity and abundance. However, the species number sharply decreased after two-month exposure, particularly at the tray of greatest OP (660 μg g−1 DW) treated with species number from 15 (after 30-days) to 3 (after 70-days). Other univariate indices such as abundance and biomass of benthic macrofauna also showed concentration-and time-dependent declines, indicating a potential adverse effect of OP on benthic community recolonization. Further, the multi-dimensional scaling (MDS) analysis that clearly separated two distinct faunal groups of macrobenthos during exposure supported the concentration-dependant recolonization followed by succession at the OP concentration of >7.6 μg g−1 DW. Similar to macrofauna, the meiofaunal abundance significantly decreased at the OP concentration of >7.6 μg g−1 DW, indicating certain threshold of OP between 7.6–66 μg g−1 DW that caused adverse effect on benthic community recolonization. Although the critical adverse OP concentration found in community level was relatively high compared to the environmental concentrations (ppb levels) reported in coastal sediments, it should be pointed out that certain species could be influenced by the exposure of lower OP concentrations.

During a search for keratinocyte differentiation-related genes, we obtained a cDNA fragment from the 5'-untranslated region of a previously identified splicing variant of desmoglein 3 (Dg3). This transcript encodes a protein of 282 amino acids, which corresponds to the N-terminal truncated intracellular domain of Dg3 (?NDg3). Northern blot analysis detected a 4.6-kb transcript matching the predicted size of ?NDg3 mRNA, and Western blot analysis with an antibody raised against the Dg3 C-terminus (H-145) detected a 31-kDa protein. Increased ?NDg3 expression was observed in differentiating keratinocytes by RT-PCR and Western blot analysis, suggesting that ?NDg3 is indeed a differentiation-related gene product. In immunohistochemical studies of normal and pathologic tissues, H-145 antibody detected the protein in the cytoplasm of suprabasal layer cells, whereas an antibody directed against the N-terminal region of Dg3 (AF1720) reacted with a membrane protein in the basal layer. In addition, ?NDg3 transcript and protein were upregulated in psoriatic epidermis, and protein expression appeared to increase in epidermal tumors including Bowen's disease and squamous cell carcinoma. Moreover, overexpression of ?NDg3 led to increased migration and weakening of cell adhesion. These results suggest that ?NDg3 have a role in keratinocyte differentiation, and that may be related with tumorigenesis of epithelial origin.

This study focused on the determination of fracture toughness by instrumented indentation technique. A theoretical model to estimate the fracture toughness of ductile materials is proposed and used to verify those results. Modeling of IIT to evaluate fracture toughness is based on two main ideas; the energy input up to characteristic fracture initiation point during indentation was correlated with material’s resistance to crack initiation and growth, and this characteristic fracture initiation point was determined by concepts of continuum damage mechanics. The estimated fracture toughness values obtained from the indentation technique showed good agreement with those from conventional fracture toughness tests based on CTOD. In addition, we confirmed that the proposed model can be also applied in the brittle material through modification of void volume fraction.

The instrumented indentation technique (IIT) has recently attracted significant research interest because it is nondestructive and easy to perform, and can characterize materials on local scales. Residual stress can be determined by analyzing the indentation load-depth curve from IIT. However, this technique using a symmetric indenter is limited to an equibiaxial residual stress state. In this study, we determine the directionality of the non-equibiaxial residual stress by using the Knoop indentation technique. Different indentation load-depth curves are obtained at nonequibiaxial residual stresses depending on the Knoop indentation direction. A model for Knoop indentation was developed through experiments and theoretical analysis.

The material characterization on the weak points of the structural systems is essential to evaluate safety accurately. However, general material characterization methods such as uniaxial tensile test and CTOD (crack tip opening displacement) test are destructive, therefore, it cannot be applied to the system in use. To overcome this problem, the material characterization using instrumented indentation technique was developed. However, current researches on instrumented indentation technique focus on the hardness measurement. The evaluation of flow property, residual stress and fracture toughness using instrumented indentation technique is not sufficiently performed. In this paper, we introduce the evaluation method of the flow property, the residual stress near the weldment and the fracture toughness developed from damage mechanics. The algorithm of flow property evaluation, the residual stress evaluation model and the fracture toughness model by using indentation were verified comparing with the experimental results.

Flow properties and stress state are indispensable factors for safety assessment of structural materials in operation, which were evaluated using instrumented indentation tests (IITs). Flow properties were obtained by defining representative stress and strain, and IIT results for 10 steel materials were discussed by comparing with those from uniaxial tensile tests. The indentation load-depth curve is significantly affected by the presence of residual stress, and the stress-induced load change was converted to a quantitative stress value. The stress state of a friction stir-welded joint of API X80 steel was evaluated and compared with that measured by energy-dispersive X-ray diffraction.

An indentation fracture toughness model is applied to estimate non-destructively the fracture toughness of power plant materials such as ASTM A53 and ASME SA335 P91. Fracture toughness evaluated using the model showed good agreement with current standard fracture toughness test results.

Abstract In watermelon, grafting of seedlings to rootstocks is necessary because watermelon roots are less viable than the rootstock. Moreover, commercially important watermelon varieties require disease-resistant rootstocks to reduce total watermelon yield losses due to infection with viruses such as cucumber green mottle mosaic virus (CGMMV). Therefore, we undertook to develop a CGMMV-resistant watermelon rootstock using a cDNA encoding the CGMMV coat protein gene (CGMMV-CP), and successfully transformed a watermelon rootstock named ‘gongdae’. The transformation rate was as low as 0.1–0.3%, depending on the transformation method used (ordinary co-culture vs injection, respectively). However, watermelon transformation was reproducibly and reliably achieved using these two methods. Southern blot analysis confirmed that the CGMMV-CP gene was inserted into different locations in the genome either singly or multiple copies. Resistance testing against CGMMV showed that 10 plants among 140 T1 plants were resistant to CGMMV infection. This is the first report of the development by genetic engineering of watermelons resistant to CGMMV infection.

TLP method was applied to the lead free soldering process; Sn-3.5Ag core solder (Tm of 221°C) / Sn-Bi coating layer (Tm of 139°C at eutectic) was reflowed on UBM pad. Sn-Bi was formed by electroplating method at current range of 2~6A/dm2, which had varied the coating layer composition from 96wt% to 28wt% Bi. Specimens were reflowed on copper pad at temperature range of 200 and 220°C, and then interface reaction was examined. It was claimed that high Bi adding in the plated layer improved the wetting performance on Cu. Even at the reflow temperature of 200°C, SEM observation revealed well-defined interface junctions between solder and copper pad, i.e. nucleation and growth of CuxSn intermetallic compound. After heating for 5min at 220℃, Bi was resolved into Sn-3.5Ag core solder and completely homogenized, which is favorable from the viewpoint of long term fatigue reliability.

Not Available

Advanced constitutive relations are used in geotechnical engineering to capture measured soil and rock behaviour in the laboratory, and in numerical models to represent the material response. These constitutive relations have traditionally been difficult to use, understand, and develop except by a limited number of specialists. This paper describes a framework for transforming the representation of constitutive relations, as well as stress and strain quantities from a series of mathematical equations and matrix quantities to multidimensional geometric/visual objects in a dynamic interactive colour‐rich display environment. The paper proposes a shift in current approaches to the development of constitutive equations and their use in numerical simulations by taking advantage of rapid advancements in information technology and computer graphics. A novel interactive visualization development and learning environment for material constitutive relations referred to as VizCoRe is presented. Visualization examples of two constitutive relations, the linear elastic with von Mises failure criteria and the Modified Cam Clay (MCC) are shown. These include two‐ and three‐dimensional renderings of stress states and paths and yield and failure surfaces. In addition, the environment allows for the visualization of the implicit integration algorithm used for the numerical integration of both constitutive models. Copyright © 2002 John Wiley & Sons, Ltd.

Abstract: Ion-beam assisted deposition (IBAD) for Cr/Cu coatings was investigated. For high density and electric resistivity, IBAD was found to be an appropriate method. The density was increased from 8.60 g/cm3 to 8.85 g/cm3, depending on IBAD conditions, and the resistivity was increased from 6.4 μΩ·cm to 7.2 μΩ·cm. It is also suggested that the crystallographic orientations of polycrystalline Cu surfaces were able to be aligned to (111) planes by the IBAD process.