Synthesis and characterization of crosslinked polyurethanes

Two polyurethane samples, crosslinked with aliphatic hyperbranched polyester, were synthesized and examined in this work. The sample PUPDMS-EO was prepared using ethylene oxide-poly(dimethylsiloxane)-ethylene oxide as macrodiol, while the synthesis of PUPTMO was performed using poly(tetramethyleneoxide). The obtained results show that thermal stability of these networks can be improved by introducing the siloxane sequences. However, the sample PUPDMS-EO has at the same time much lower crosslinking density than PUPTMO.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Surface modification of graphitic carbon nitride with copper nanoparticles

Two different synthetic routes were employed to modify surface of graphitic carbon nitride (gCN) with copper nanoparticles (CuNPs). Structure, morphology and CuNPs distribution on presynthesized g-CN surface are characterized by FT-IR, XRD and TEM. Results suggested that the simpler method based on mixing of precursors in inert atmosphere and room temperature, resulted in better CuNPs distribution compared to method which used refluxing as a step in synthesis

Interaction of gold nanoparticles with rat brain synaptosomal plasma membrane Na+/K+-ATPase and Mg2+-ATPase

The aim of the work was to investigate the interaction between borate capped gold nanoparticles (AuNPs) and the rat brain synaptosomal plasma membranes (SPM), as well as the effects of these AuNPs on SPM Na+ /K+ - ATPase and Mg2+-ATPase activity. Influence of AuNPs on Na+ /K+ -ATPase and Mg2+-ATPase activity was investigated as the function of AuNPs and protein concentration and preincubation time. AuNPs induced the stimulation of Na+ /K+ -ATPase activity for more than 100%, while Mg2+-ATPase activity reminded unaffected. We propose that this stimulation of enzyme activity was a consequence of an increase of the active surface of membranes.Physical chemistry 2012 : 11th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 201

The antimicrobial activity of triangular silver nanoplates on cotton fabric pretreated with chitozan

Triangular silver nanoplates are a type of most-studied noble-metal nanostructures over the past decade, owing to their special structural architecture, outstanding plasmonic features across both visible and IR regions, and catalytic properties for a wide range of applications. Herein, we used these nanoparticles to deposit on cotton (Co) fabric pretreated with biopolymer chitosan (CHT) and investigated their antimicrobial activity. The antimicrobial efficiency of the coated fabrics was evaluated toward Gram-negative bacteria E. coli, Gram-positive bacteria S. aureus and fungus C. albicans. It was found that deposited silver nanoparticles imparted excellent antimicrobial properties to Co fabric

Antibacterial activity of copper nanoparticles

Copper nanoparticles (CuNPs), with an average particle size of about 5 nm, was prepared by the simple chemical reduction procedure. TEM and UV– Vis spectroscopy contributed to the analysis of size and optical properties of CuNPs, and their antibacterial activity was evaluated toward human pathogenic bacteria Escherichia coli and Staphylococcus aureus, in a concentration dependent manner. The changes in the cell membrane morphology of tested strains were investigated by atomic force microscope (AFM), after 2 h of their contact with CuNPs. It was found that CuNPs cause different types of cell membrane disruptions, as well as that S. aureus bacteria were slightly resistant to the cell membrane damage than E. coli

Adsorption of Organophosphate Pesticide Dimethoate on Gold Nanospheres and Nanorods

Organophosphorus pesticide dimethoate was adsorbed onto gold nanospheres and nanorods in aqueous solution using batch technique. Adsorption of dimethoate onto gold nanoparticles was confirmed by UV-Vis spectrophotometry, TEM, AFM, and FTIR analysis. The adsorption of nanospheres resulted in aggregation which was not the case with nanorods. Nanoparticles adsorption features were characterized using Langmuir and Freundlich isotherm models. The Langmuir adsorption isotherm was found to have the best fit to the experimental data for both types of nanoparticles. Adsorption capacity detected for nanospheres is 456 mg/g and for nanorods is 57.1 mg/g. Also, nanoparticles were successfully used for dimethoate removal from spiked drinking water while nanospheres were shown to be more efficient than nanorods

A fluorescent nanoprobe for single bacterium tracking: functionalization of silver nanoparticles with tryptophan to probe the nanoparticle accumulation with single cell resolution

The investigation of the interaction of silver nanoparticles and live bacteria cells is of particular importance for understanding and controlling their bactericidal properties. In this study, the process of internalization of silver nanoparticles in Escherichia coli cells was followed by means of synchrotron excitation deep ultraviolet (DUV) fluorescence imaging. Antimicrobial nanostructures that can absorb and emit light in the UV region were prepared by functionalization of silver nanoparticles with tryptophan amino acid and used as environmentally sensitive fluorescent probes. The nanostructures were characterized by morphological (TEM) and spectroscopic methods (UV-vis, FTIR, XPS, and photoluminescence). The TEM images and the analyses of the UV-vis spectra suggested that the addition of tryptophan led to the formation of hybrid nanostructures with pronounced eccentricity and larger sizes with respect to that of the initial silver nanoparticles. The DUV imaging showed that it was possible to distinguish the fluorescent signal pertaining to silver-tryptophan nanostructures from the autofluorescence of the bacteria. The spatial resolution of the fluorescence images was 154 nm which was sufficient to perform analyses of the accumulation of the nanostructures within a single bacterium. The DUV imaging results imply that the tryptophan-functionalized silver nanoparticles interact with cell membranes via insertion of the amino acid into the phospholipid bilayer and enter the cells

Looking for leakage or monitoring for public assurance?

Monitoring is a regulatory requirement for all carbon dioxide capture and geological storage (CCS) projects to verify containment of injected carbon dioxide (CO2) within a licensed geological storage complex. Carbon markets require CO2 storage to be verified. The public wants assurances CCS projects will not cause any harm to themselves, the environment or other natural resources. In the unlikely event that CO2 leaks from a storage complex, and into groundwater, to the surface, atmosphere or ocean, then monitoring methods will be required to locate, assess and quantify the leak, and to inform the community about the risks and impacts on health, safety and the environment. This paper considers strategies to improve the efficiency of monitoring the large surface area overlying onshore storage complexes. We provide a synthesis of findings from monitoring for CO2 leakage at geological storage sites both natural and engineered, and from monitoring controlled releases of CO2 at four shallow release facilities – ZERT (USA), Ginninderra (Australia), Ressacada (Brazil) and CO2 field lab (Norway)