Characterization is absolutely necessary and is a must in order to understand and estimate different silver nanoparticle (nm) size in specific group wise manner which corresponds to group wise in number & sizes, a...Characterization is absolutely necessary and is a must in order to understand and estimate different silver nanoparticle (nm) size in specific group wise manner which corresponds to group wise in number & sizes, and their importance and effect on biological tissue and organs with agglomeration for nano toxicological studies in environments, the acute toxicity of colloidal silver nano particles (AgNps) were studied in fresh dissected tissues of Swiss Albino mice and their fetuses. In this manuscript, an attempt is made to demonstrate the synthesis and characterization of silver nano particles with a wide range of sizes (from 2.75 nm up to 1908.2 nm in radius) by reducing silver nitrate powder with polyvinyl pyrollidone in aqueous solutions in the presence of a sodium borohydride stabilizer. The resulting particles were found spherical aggregates with a rough surface and poly dispersity index below 18.26% (>0.783 PDI). The particle optical, cumulative, diluents and electrical conductivity properties were examined by dynamic light scattering and zeta potential but morphology was evaluated after examination by transmission electron microscopy & image-j. Silver nanoparticles were directly coated with polyvinyl pyrollidone with a sodium borohydride stabilizer. Optical properties on a single-particle level were studied by means of auto correlation function measurements. The effective poly dispersity index of the charged silver nanoparticles was low enough to form a colloidal crystal at low ionic strength. Colloidal form is found more toxic than suspended particles in 1.5 molar sodium chloride solution;this shows increase of silver nanoparticles size due to agglomeration, will reduce the toxicity but increase teratogenicity.展开更多
This study introduces measures to identify resonant (concentration of energy in a single or a few frequencies) or unfavorable earthquake ground motions. Probabilistic measures based on the entropy rate and the geometr...This study introduces measures to identify resonant (concentration of energy in a single or a few frequencies) or unfavorable earthquake ground motions. Probabilistic measures based on the entropy rate and the geometric properties of the power spectral density function (PSDF) of the ground acceleration are developed first. Subsequently, deterministic measures for the frequency content of the ground acceleration are also developed. These measures are then used for identifying resonance and criticality in stochastic earthquake models and 110 acceleration records measured at rock, stiff, medium and soft soil sites. The unfavorable earthquake record for a given structure is defined as the record having a narrow frequency content and dominant frequency close to the structure fundamental natural frequency. Accordingly, the measures developed in this study may provide a basis for selecting records that are capable of producing the highest structural response. Numerical verifications are provided on damage caused to structures by identified resonant records.展开更多
文摘Characterization is absolutely necessary and is a must in order to understand and estimate different silver nanoparticle (nm) size in specific group wise manner which corresponds to group wise in number & sizes, and their importance and effect on biological tissue and organs with agglomeration for nano toxicological studies in environments, the acute toxicity of colloidal silver nano particles (AgNps) were studied in fresh dissected tissues of Swiss Albino mice and their fetuses. In this manuscript, an attempt is made to demonstrate the synthesis and characterization of silver nano particles with a wide range of sizes (from 2.75 nm up to 1908.2 nm in radius) by reducing silver nitrate powder with polyvinyl pyrollidone in aqueous solutions in the presence of a sodium borohydride stabilizer. The resulting particles were found spherical aggregates with a rough surface and poly dispersity index below 18.26% (>0.783 PDI). The particle optical, cumulative, diluents and electrical conductivity properties were examined by dynamic light scattering and zeta potential but morphology was evaluated after examination by transmission electron microscopy & image-j. Silver nanoparticles were directly coated with polyvinyl pyrollidone with a sodium borohydride stabilizer. Optical properties on a single-particle level were studied by means of auto correlation function measurements. The effective poly dispersity index of the charged silver nanoparticles was low enough to form a colloidal crystal at low ionic strength. Colloidal form is found more toxic than suspended particles in 1.5 molar sodium chloride solution;this shows increase of silver nanoparticles size due to agglomeration, will reduce the toxicity but increase teratogenicity.
基金Project (No. JSPS-P-08073)supported by the Japanese Society for the Promotion of Science
文摘This study introduces measures to identify resonant (concentration of energy in a single or a few frequencies) or unfavorable earthquake ground motions. Probabilistic measures based on the entropy rate and the geometric properties of the power spectral density function (PSDF) of the ground acceleration are developed first. Subsequently, deterministic measures for the frequency content of the ground acceleration are also developed. These measures are then used for identifying resonance and criticality in stochastic earthquake models and 110 acceleration records measured at rock, stiff, medium and soft soil sites. The unfavorable earthquake record for a given structure is defined as the record having a narrow frequency content and dominant frequency close to the structure fundamental natural frequency. Accordingly, the measures developed in this study may provide a basis for selecting records that are capable of producing the highest structural response. Numerical verifications are provided on damage caused to structures by identified resonant records.
