First graders' cognitive representation of number and understanding of place value: Cross-national comparisons: France, Japan, Korea, Sweden, and the United States.

Attempts to replicate the results of earlier research comparing US and Japanese 1st graders' cognitive representation of number and understanding of place value. First graders from France, Sweden, and Korea were also included in the study. This investigation examines the idea that variability in mathematics performance may be due, in part, to differences in cognitive representation of number that is affected by numerical language characteristics differentiating Asian- and non-Asian-language groups. Comparison of Asian- and non-Asian-language speakers revealed that the performance of the children was different across the 2 groups but similar within the groups. There is strong evidence that cognitive representation of number may differ depending on the language spoken. There were also differences in performance on place value tasks related to the language spoken. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The central position of education in knowledge mobilization: insights from network analyses of spatial reasoning research across disciplines

Scientometrics - Knowledge mobilization is becoming increasingly important for research collaborations, but few methodologies support increased knowledge sharing. This study provides insights,...     

Electrochemical enzyme immunoassay of a peptide hormone at picomolar levels

A novel electrochemical enzyme immunoassay system with a 10 ng L(-1) level detection limit was developed for the determination of B-type natriuretic peptide (BNP), an important marker for the diagnosis of heart failure. Sample BNP was added to a solution containing a certain concentration of acetylcholinesterase(AChE)-labeled anti-BNP antibody to undergo an immunological reaction. After the immunological reaction, we proposed two assay schemes. One involves measuring the amount of antibody-enzyme conjugate that reacted with two BNP molecules (reacted conjugate). The other involves measuring the amount of antibody-enzyme conjugate with at least one free binding site (unreacted conjugate). Then the amount of reacted or unreacted conjugate was determined by measuring the AChE activity after the recovery of each conjugate from the immunological reaction mixture. To determine the trace level of the recovered antibody-enzyme conjugate, the AChE activity was determined with high sensitivity on the basis of the chemisorption/electrochemical desorption process of thiocholine, which was produced through the enzymatic reaction, on a silver surface. The thiocholine chemisorption (i.e., accumulation) on the silver electrode surface resulted in a sensitivity for the electrochemical determination of the AChE activity that was 2 orders of magnitude greater than that obtained when using direct measurement without accumulation. The procedure for determining the AChE activity of unreacted conjugate after its recovery on a BNP-modified disk was applied to the determination of BNP in serum samples. This procedure involves the removal of the immunological reaction mixture before the enzymatic reaction process, which allows the AChE activity to be measured without any interference from endogenous pseudocholinesterase, which exists with high activity in serum. With both procedures, the BNP could be measured within an hour. The detection limits were 20 and 40 ng L(-1) using the reacted and unreacted conjugate measuring procedures, respectively.     

Ionically conductive polymer gel electrolytes prepared from vinyl acetate and methyl methacrylate for electric double layer capacitor

In order to obtain highly conductive polymer electrolytes for an electric double layer capacitor, three kinds of polymer gel electrolytes were prepared. Vinyl acetate (VAc) and methyl methacrylate (MMA) were copolymerized with divinyl adipate (DA) and ethylene glycol dimethacrylate (EGDMA), respectively, in propylene carbonate (PC) containing tetraethylammonium tetrafluoroborate (TEATFB) to form network polymer gel electrolytes. MMA was also copolymerized with butylene glycol DMA for comparison. The polymer gel electrolytes obtained were characterized by means of thermogravimetry, complex impedance analysis, and cyclic voltammetry for use in the electric double layer capacitor. The ionic conductivities of the polymer gel electrolytes were dependent on the TEATFB concentration, temperature, and crosslinking degree. The polymer gel electrolytes in the VAc‐DA system exhibited higher room temperature conductivities (10⁻² S/cm) than those in the MMA‐EGDMA system. Further, the polymer gel electrolytes in the VAc‐DA system showed good electrochemical stability windows ranging from −4.0 to 4.0 V versus Ag. Thermal analysis revealed that the polymer gel electrolytes in both systems were stable up to 150°C. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 12–18, 2000     

Fire-resistant nonwovens of EVOH and PET treated with amorphous sodium polyborate

Nonwovens made of poly(ethylene terephthalate) (PET) and ethylene–vinyl alcohol copolymer (EVOH) are found to become highly fire resistant by treating with amorphous sodium polyborate (SPB). The fire-resistant nonwovens with 10-mm thickness show a gradual temperature increase up to 127 °C and no hole, when their back sides are fired with a gas burner for 12 min. The analysis using the EPMA and the DTA/TG indicates that the SPB foam promotes the formation of char (carbon) layer, and that the char layer together with the SPB foam insulates inside from the oxygen and the heat.     

Establishment of a model substrate oil for antioxidant activity assessment by oil stability index method

A model substrate oil using methyl linoleate was established for the determination of the antioxidant activity by Oil Stability Index (OSI) method. OSI values for methyl linoleate with different concentrations (5–100%) in silicone oil were measured at different temperatures (70–120°C). As the temperature increased, the OSI value decreased in each concentration of methyl linoleate. Optimal temperature and concentration of antioxidants, α-tocopherol, and butylated hydroxytoluene on OSI values for 10% methyl linoleate model oil was measured at 90, 100, 110, and 120°C. The logarithmic relationship between temperature and OSI using model substrate oil was similar to that of soybean oil. Furthermore, application of some spice extracts to this model oil system was carried out to give results thhat compared well with those available in the literature. Thus, the procedure using methyl linoleate-silicone oil as a model substrate oil is available for evaluating the antioxidant activity by the OSI method.     

Oxygen ion conductivity of the ceria-samarium oxide system with fluorite structure

Ionic conduction of oxygen in the ceria-samarium oxide system was investigated as a function of temperature, partial pressure of oxygen and the oxide composition, together with its crystal structure, density and defect structure. The ionic conductivity of (CeO₂)_1–x(SmO_1.5)_x was the highest in ZrO₂-, ThO₂- and CeO₂-based oxide systems. The system CeO₂-SmO_1.5 consisted of the solid solution with a fluorite structure atx<50 at.%. The ionic transference number was nearly unity between 600 and 900°C. With an increase in Sm₂O₃ content, the ionic conductivity gradually decreased due to a decrease in mobility of oxygen ions. The samarium oxide-doped ceria was less reducible than pure and alkaline earth oxide-doped ceria.     

Di(2-ethylhexyl) phthalate contamination of retail packed lunches caused by PVC gloves used in the preparation of foods

Plasticizer contamination of foods sold in retail packed lunches and set lunches in restaurants was determined by GC/MS. The phthalate esters were as follows: diethyl, dipropyl, dibutyl, dipentyl, dihexyl, butylbenzyl, dicyclohexyl, di(2-ethylhexyl), dioctyl, diisooctyl (mixture of isomers) and diisononyl (mixture). Di(2- ethylhexyl) adipate was also determined. Sixteen packed lunches and ten set lunches were analysed, and in all samples the concentration of di(2-ethylhexyl) phthalate (DEHP) was the highest, at 0.80-11.8 mg/ kg in packed lunches and 0.012-0.30 mg/kg in set lunches. The DEHP content of five packed lunches exceeded 1.85 mg, which is the EU tolerable daily intake (TDI) for a person of 50 kg body weight. Foodstuffs that were components of the packed lunches were taken from the factory at each step of preparation and phthalates were determined. For example, chicken contained 0.08 mg/kg DEHP when uncooked, 13.1 mg/ kg after frying and 16.9 mg/kg after packing. Disposable PVC gloves used in the preparation of foods were apparently the source of high DEHP concentrations. The gloves used during cooking or packaging were sprayed with 68% (w/w) ethanol to sterilize them. PVC gloves from the factory contained 22 or 41% by weight of DEHP. To confirm the link with the contamination problem, samples of boiled rice, croquette and boiled dry radish were handled in the laboratory with PVC gloves containing 30% (w/w) DEHP. DEHP migration levels of 0.05 mg/kg in rice or 0.33 mg/kg in croquette, and 11.1 mg/kg in radish were found. The alcohol sprayed onto the gloves increased the migration of DEHP to 2.03 mg/kg in rice, 2.45 mg/ kg in croquette, and 18.4 mg/kg in radish.     

Migration of di(2-ethylhexyl) phthalate from polyvinyl chloride tubes used in preparation of foods

Three samples of polyvinyl chloride products for food use were examined for di(2-ethylhexyl) phthalate (DEHP) migration levels under the conditions described in the Japanese Food Sanitation Law. These samples were two kinds of tubes and one stretched film, containing 12 to 41% DEHP by weight. DEHP migration levels from them were very low, all below 0.1 ppm, into 3 kinds of food simulant; water, 4% acetic acid and 20% ethanol. However, high levels of DEHP migrated into n-heptane, 12 ppm from the stretched film sample and more than 800 ppm from the tube samples. Migration from the 2 tubes was higher than 150 ppm, the limit of residues after evaporation in containers and wraps. Though the limit of residues after evaporation is not set for equipment used in the preparation of foods, the tested tubes were considered to be unsuitable for uses in which they come into direct contact with oils, fats or oily foods.     

The role of impressions on users’ tactile interaction with product materials: An analysis of associative concept networks

Depth impressions are an inner associative layer of humans’ expressed impressions. To analyze tactile interaction, it is essential to examine what users feel and imagine and how they create depth impressions by touching and looking at different product materials. On the basis of tactile interactions, this study aims to capture and analyze users’ depth impressions of materials. This research also proposes an ‘impressionably’ new tactile material for design from the viewpoint of depth impressions. To capture depth impressions, we investigated users’ tactile interactions in an experiment. The experiment used samples of six common natural and artificial materials, along with the proposed new micro-print-based material. A concept network-based method was employed in two stages to analyze the experimentally obtained verbalized protocols and to identify any depth impressions. This method allowed us to capture and analyze the depth impressions behind the surface impressions. This research found that the feel of materials’ tactile naturalness and users’ habituation to the tested samples are related to their depth impressions and the complexity of their concept networks. The depth impressions and concept network of the proposed micro-print material are distinct and beyond those for existing natural or artificial materials. These findings will provide the basis for employing new analysis tools and facilitate the development of impressionably better tactile materials for design.