A spatial and temporal analysis of child pedestrian crashes in Santiago,Chile

This paper presents a spatial and temporal analysis of child pedestrian crash data in Santiago, Chile during the period 2000–2008. First, this study identified seven critical areas with high child pedestrian crash risk employing kernel density estimation, and subsequently, statistically significant clusters of the main attributes associated to these crashes in each critical area were determined in a geographic information systems environment. Moran's I index test identified a positive spatial autocorrelation on crash contributing factors, time of day, straight road sections and intersections, and roads without traffic signs within the critical areas during the studied period, whereas a random spatial pattern was identified for crashes related to the age attribute. No statistical significance in the spatial relationship was obtained in child pedestrian crashes with respect to gender, weekday, and month of the year. The results from this research aid in determining the areas in which enhanced school-age child pedestrian safety is required by developing and implementing effective enforcement, educational, and engineering preventive measures.     

Isolation and identification of a ferulic acid dehydrotrimer from saponified maize bran insoluble fiber

Following saponification of maize bran insoluble fiber a ferulic acid dehydrotrimer was isolated using Sephadex LH-20 chromatography. Structural identification was carried out using UV-spectroscopy, mass spectrometry and 1D and 2D NMR experiments ( ¹H, ¹³C, DEPT, COSY, TOCSY, ¹³C- ¹H HSQC, HMBC). UV-spectroscopy indicated characteristics of ferulate structures, mass spectrometry showed a trimeric ferulate structure, and the NMR spectra provided diagnostic evidence for its being a 5-5/8-O-4-coupled dehydrotrimer. Ferulic acid dehydrodimers are mainly derived from diferulates which cross-link polysaccharides. Because of the involvement of a 5-5-dehydrodiferulic acid unit in the identified trimer, this novel dehydrotriferulic acid from cereal grain fiber need not imply the cross-linking of three polysaccharide chains; molecular modeling of the ferulate dehydrodimerization in earlier studies showed that the 5-5-diferulate, uniquely, can form intramolecularly. This first identified ferulic acid dehydrotrimer nevertheless reveals that polysaccharide chains can be more extensively cross-linked than previously recognized.     

Wear Performance of Dental Materials: A Comparison of Substructure Ceramics,Veneering Ceramics,and Non‐Precious Alloys

The aim of this in vitro study was to compare the two‐body wear resistance of different dental ceramics and non‐precious alloys. Two‐body wear tests were performed in a chewing simulator with steatite antagonists. A pin‐on‐block design with a vertical load of 50 N for 1.2 × 10⁵ cycles (f = 1.6 Hz; lateral movement: 1 mm, mouth opening: 2 mm) was used for the wear test. Surface roughness R_a (SP6, Perthen‐Feinprüf, G) and wear depth were determined using a 3D‐Profilometer (Laserscan 3D, Willytec, G). Scanning electron microscopy (Quanta FEG 400, FEI, NL) was applied for evaluating wear performance of both, materials and antagonists. Statistics: one‐way ANOVA (α = 0.05). The in vitro wear test showed that the wear performance of dental materials is strongly influenced by the type of material (ceramic, zirconia, or alloy). Zirconia and alloy provided low wear in contrast to glass‐ceramic systems. In contradiction to common expectations, hard zirconia and alloy systems showed even lower antagonistic wear than glass‐ceramics.     

铬鞣革的体相与表面化学相关性及Cr(Ⅲ)和Cr(Ⅵ)的释放

欧洲约有1%~3%的一般人群对铬(Cr)过敏。从人类健康和环境风险的角度来看,评估皮革内潜在的Cr(Ⅲ)和Cr(Ⅵ)释放十分重要。研究考察了皮革体相和表面化学的相关性、Cr(Ⅲ)和Cr(Ⅵ)的释放,以及具有联合释放能力的特定皮革,对释放的铬的还原和络合。采用SEM、EDS、XPS、ATR-FTIR和二苯卡巴肼比色法表征4种皮革。将皮样与人工汗(ASW,pH6.5)和缓冲液(PB,pH 7.5~8.0)接触,采用分光光度法和AAS,对比Cr(Ⅲ)和Cr(Ⅵ)释放效果。具有联合释放能力的特定皮革,在ASW和PB中,能够有效减少Cr(Ⅵ)的含量,其还原能力与革表面及释放的铬的含量相关。采用ATR-FTIR表征不具有该能力且含有较少芳烃基的皮革。结果表明,在革表面和PB溶液中均存在Cr(Ⅵ)。     

Measurements of size distribution nanoparticles in ultraviolet‐curable methacrylate‐based boehmite nanocomposites

A deep study on the possibility to increase the quality of the dispersion of organically modified Boehmite nanoparticles into photo‐polymerizable methacrylic‐siloxane monomers, to be used as coatings, was conducted using unconventional indirect analyses. The nanocomposite were produced using two different procedures, starting from the conventional “solvent dispersion method.” The two procedures used differ for the technique used to obtain the dispersion of Boehmite, i.e., sonication or magnetic stirring and for the time used in each procedure. The efficiency of each method of preparation of nanostructured systems was analyzed, both in the liquid (uncured) and ultraviolet (UV) cured state. First, dynamic light scattering and rheological measurements were performed on the liquid suspensions, supplying experimental data used in proper theoretical models to estimate the dimensions and distribution of Boehmite particles. The suspensions obtained with the two different methods were, then, UV cured obtaining thin and thick films, on which scanning electron microscopy and transmittance measurements were performed. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Chemistry and Antioxidant Properties of Essential Oil and Oleoresins Extracted from the Seeds of Tomer (Zanthoxylum armatum DC)*

The seeds of Zanthoxylum armatum DC, on hydrodistillation, yielded 1.2% of the essential oil. The oleoresins were extracted by a Soxhlet extractor using ethanol, ethyl acetate, and isopropyl alcohol. Gas chromatography-mass spectrometry analysis of the essential oil resulted in the identification of 38 components, of which linalool (62%) and limonene (18.1%) were the major components. The major components of oleoresins were linoleic acid, palmitoleic acid, and linalool. The antioxidant potential of essential oil and oleoresins were evaluated by 2,2′-diphenyl picrylhydrazyl radical scavenging, Fe²⁺ chelating, ferric thiocyanate method, and various lipid peroxidation assays. The essential oil showed maximum antioxidant potential, whereas oleoresins showed moderate antioxidant activity.     

Detwinning Phenomenon and Its Effect on Resulting Twinning Structure of an Austenitic Hadfield Steel

Metallurgical and Materials Transactions A - Hadfield Steel shows high strain hardening which can be linked to its ability to form twins during mechanical loading. Twinning in Hadfield Steel is...     

Polymerization of MMA at the surface of inorganic submicron particles

Inorganic submicron particles, such as TiO₂, were modified with titanate coupling agents. The structure and stability of some titanates, both in solution and at the particle surface, were investigated by various methods. The modified titanium dioxide was dispersed in a solution of sodium dodecylsulphate (SDS) in water. The surfactant adsorbs at the now hydrophobic particle surface, thus creating a micellelike structure with an inorganic particle in the centre. In this system an emulsion polymerization of methyl methacrylate was carried out. Product formed at the particle surface is either physically bound by entanglement or chemically bound by covalent bonding to the titanates. In this way a core-shell morphology is obtained with an inorganic core and a polymer shell. The effects of several reaction parameters on the kinetics of the polymerization were studied. The encapsulated TiO₂ particles may offer interesting prospects in those applications where good coupling between polymer matrix and inorganic particles is necessary, such as latex paints and polymer composite materials.     

The ESTEEM platform: enabling P2P semantic collaboration through emerging collective knowledge

In this paper, we present Esteem (Emergent Semantics and cooperaTion in multi-knowledgE EnvironMents), a community-based P2P platform for supporting semantic collaboration among a set of independent peers, without prior reciprocal knowledge and no predefined relationships. Goal of Esteem is to go beyond the existing state-of-the-art solutions for P2P knowledge sharing and to provide an integrated platform for both data and service discovery. A distinguishing feature of Esteem is the use of semantic communities to explicitly give shape to the collective knowledge and expertise of peer groups with similar interests. Key techniques of Esteem will be presented in the paper and concern: shuffling-based communication, ontology and service matchmaking, context management, and quality-aware data integration. An application example of data and service discovery in the health-care domain will be presented, by also discussing results of system and user evaluation.