The production of silver nanoparticles(AgNPs) has increased tremendously during recent years due to their antibacterial and physicochemical properties. As a consequence, these particles are released inevitably into th...The production of silver nanoparticles(AgNPs) has increased tremendously during recent years due to their antibacterial and physicochemical properties. As a consequence, these particles are released inevitably into the environment, with soil being the main sink of disposal. Soil interactions have an effect on AgNP mobility, transport and bioavailability. To understand AgNP adsorption processes, lab-controlled kinetic studies were performed.Batch tests performed with five different Mediterranean agricultural soils showed that cation exchange capacity and electrical conductivity are the main parameters controlling the adsorption processes. The adsorption kinetics of different sized(40, 75, 100 and 200 nm)and coated(citrate, polyvinylpyrrolidone and polyethyleneglycol(PEG)) AgNPs indicated that these nanoparticle properties have also an effect on the adsorption processes.To assess the mobility and bioavailability of AgNPs and to determine if their form is maintained during adsorption/desorption processes, loaded soils were submitted to leaching tests three weeks after batch adsorption studies. The DIN 38414-S4 extraction method indicated that AgNPs were strongly retained on soils, and single-particle inductively coupled plasma mass spectrometry confirmed that silver particles maintained their nanoform, except for 100 nm PEG-AgNPs and 40 nm citrate-coated AgNPs. The DTPA(diethylenetriaminepentaacetic acid) leaching test was more effective in extracting silver,but there was no presence of AgNPs in almost all of these leachates.展开更多
The aim of this work is to study the interaction of spoken words and images that are used within programs targeted to popularize knowledge among teenagers. We will look into the program Bit@bit developed by Television...The aim of this work is to study the interaction of spoken words and images that are used within programs targeted to popularize knowledge among teenagers. We will look into the program Bit@bit developed by Television de Catalunya, which is intended to disseminate computer concepts, tools and procedures. In this kind of program, one can find spoken language (on/off screen voices, interviews, etc.), other oral material (sounds, music, songs), written language (descriptions, title sequences, inserts and Uniform Resource Locator, or electronic addresses), and other visual material (film cut images, advertising, other TV programs, cartoons, films, both location or studio images, depicting reality, or computer screens, or logotypes). The profusion of multimodal elements used in this program helps to keep the young audience's attention. The use of references to their world or knowledge, as a target group, is based on interplay among different semiotic strategies. At the same time, the entire program's multi-segmentation into short video clips, combined with a fast paced sound track helps its audience to understand the specialized explanations presented. Of all the multimodal wealth that the program presents, we will concentrate only on the relationship between the words and the images (leaving other secondary semiotics to one side), the main strategy for achieving the objective of transmitting knowledge and winning adolescent audiences.展开更多
基金The Spanish Ministry of Economy and Competitiveness financed this work through the project CGL2013-48802-C3-2-R(Program 2014)the Spanish Ministry of Economy and Competitiveness(Ref.BES-2014-070625)the University of Girona for financial support(MPCUdG2016/103)
文摘The production of silver nanoparticles(AgNPs) has increased tremendously during recent years due to their antibacterial and physicochemical properties. As a consequence, these particles are released inevitably into the environment, with soil being the main sink of disposal. Soil interactions have an effect on AgNP mobility, transport and bioavailability. To understand AgNP adsorption processes, lab-controlled kinetic studies were performed.Batch tests performed with five different Mediterranean agricultural soils showed that cation exchange capacity and electrical conductivity are the main parameters controlling the adsorption processes. The adsorption kinetics of different sized(40, 75, 100 and 200 nm)and coated(citrate, polyvinylpyrrolidone and polyethyleneglycol(PEG)) AgNPs indicated that these nanoparticle properties have also an effect on the adsorption processes.To assess the mobility and bioavailability of AgNPs and to determine if their form is maintained during adsorption/desorption processes, loaded soils were submitted to leaching tests three weeks after batch adsorption studies. The DIN 38414-S4 extraction method indicated that AgNPs were strongly retained on soils, and single-particle inductively coupled plasma mass spectrometry confirmed that silver particles maintained their nanoform, except for 100 nm PEG-AgNPs and 40 nm citrate-coated AgNPs. The DTPA(diethylenetriaminepentaacetic acid) leaching test was more effective in extracting silver,but there was no presence of AgNPs in almost all of these leachates.
文摘The aim of this work is to study the interaction of spoken words and images that are used within programs targeted to popularize knowledge among teenagers. We will look into the program Bit@bit developed by Television de Catalunya, which is intended to disseminate computer concepts, tools and procedures. In this kind of program, one can find spoken language (on/off screen voices, interviews, etc.), other oral material (sounds, music, songs), written language (descriptions, title sequences, inserts and Uniform Resource Locator, or electronic addresses), and other visual material (film cut images, advertising, other TV programs, cartoons, films, both location or studio images, depicting reality, or computer screens, or logotypes). The profusion of multimodal elements used in this program helps to keep the young audience's attention. The use of references to their world or knowledge, as a target group, is based on interplay among different semiotic strategies. At the same time, the entire program's multi-segmentation into short video clips, combined with a fast paced sound track helps its audience to understand the specialized explanations presented. Of all the multimodal wealth that the program presents, we will concentrate only on the relationship between the words and the images (leaving other secondary semiotics to one side), the main strategy for achieving the objective of transmitting knowledge and winning adolescent audiences.