Optical Drug Monitoring: Photoacoustic Imaging of Nanosensors to Monitor Therapeutic Lithium in Vivo

Personalized medicine could revolutionize how primary care physicians treat chronic disease and how researchers study fundamental biological questions. To realize this goal, we need to develop more robust, modular tools and imaging approaches for in vivo monitoring of analytes. In this report, we demonstrate that synthetic nanosensors can measure physiologic parameters with photoacoustic contrast, and we apply that platform to continuously track lithium levels in vivo. Photoacoustic imaging achieves imaging depths that are unattainable with fluorescence or multiphoton microscopy. We validated the photoacoustic results that illustrate the superior imaging depth and quality of photoacoustic imaging with optical measurements. This powerful combination of techniques will unlock the ability to measure analyte changes in deep tissue and will open up photoacoustic imaging as a diagnostic tool for continuous physiological tracking of a wide range of analytes

Rheological, physicochemical, and microstructural properties of asphalt binder modified by fumed silica nanoparticles

Warm mix asphalt (WMA) is gaining increased attention in the asphalt paving industry as an eco-friendly and sustainable technology. WMA technologies are favorable in producing asphalt mixtures at temperatures 20–60 °C lower in comparison to conventional hot mix asphalt. This saves non-renewable fossil fuels, reduces energy consumption, and minimizes vapors and greenhouse gas emissions in the production, placement and conservation processes of asphalt mixtures. At the same time, this temperature reduction must not reduce the performance of asphalt pavements in-field. Low aging resistance, high moisture susceptibility, and low durability are generally seen as substantial drawbacks of WMA, which can lead to inferior pavement performance, and increased maintenance costs. This is partly due to the fact that low production temperature may increase the amount of water molecules trapped in the asphalt mixture. As a potential remedy, here we use fumed silica nanoparticles (FSN) have shown excellent potential in enhancing moisture and aging susceptibility of asphalt binders. In this study, asphalt binder modification by means of FSN was investigated, considering the effects of short-term and long-term aging on the rheological, thermal, and microstructural binder properties. This research paves the way for optimizing WMA by nanoparticles to present enhanced green asphalt technology

The effects of subchronic lithium administration in male Wistar mice on some biochemical parameters

Lithium salts are efficiently used for treatment of psychiatric disorders. However, prolonged treatment frequently involves adverse side-effects. In the present work, effects of lithium carbonate administration on some biochemical parameters were studied in male mice. Lithium carbonate (20, 40 or 80 mg/kg body weight, corresponding to 3.77, 7.54 or 15.08 mg Li element/kg body weight, respectively) was injected daily for 14 or 28 days. The following parameters were recorded: water consumption, body weight, lithium and testosterone serum concentrations, activities of catalase (CAT), superoxide-dismutase (SOD) and glutathione-peroxidase (GPX) and level of lipid peroxidation (expressed as TBARS) in liver was performed. Lithium treatment, especially at the highest dose for 28 days, was found to induce weight gain, polydipsia and a significant decrease of plasma testosterone level. Lipid peroxidation level and activities of SOD and GPX were increased in liver which suggests a perturbation of the antioxidative status. Our results indicate that subchronic exposure to lithium, which induces weight gain and polydipsia under our experimental conditions, also damages the male reproductive system and triggers an oxidative stress in the liver

Synthesis of some cationic gemini surfactants and their inhibitive effect on iron corrosion in hydrochloric acid medium

Some gemini surfactants in the series of 1,2-ethane bis(dimethyl alkyl (CnH2n+1) ammonium bromide) referred as n-2-n have been synthesized, where n = 10, 12 and 14. The purity of surfactants synthesized was checked by rutinary methodologies (1H-NMR, MS and elemental analysis). Their surface active properties at equilibrium in water at 25 °C were determined. The inhibitive effect of these compounds, in the case of iron immersed in 1 M HCl, was investigated through mass-loss, potentiokinetic methods and electrochemical impedance spectroscopy. Polarization data indicate that these compounds act as very good cathodic inhibitors of iron in 1 M HCl. In the anodic range, the surfactants studied do not show an inhibition effect at iron electrode potential more positive than -100 mV/Saturated Calomel Electrode. Impedance plots of iron in the presence of various concentrations of surfactants studied are similar to semicircles in the capacitive quadrant. The associated values of transfer resistances increase by increasing the additive concentrations. From all measurements performed, the variation of the inhibition efficiency versus concentration shows the same trend. The gemini surfactants appear to be adsorbed in the metal/liquid interface through the general adsorption mode following the Frumkin adsorption isotherm model. The electrochemical impedance spectroscopy shows that the maximum inhibition efficiency is attributed to a formation of an adsorbed layer at the iron surface. From tensiometric measurements, it was found that the ability of gemini surfactants studied to adsorb at the interface air/water is concordant with their order of the inhibition efficiency of iron corrosion.We thank the CNPRST for its financial support (PARS Chim.008) and the TWAS (Grant 97-121 RG/CHE/AF/AC).Peer reviewe

A viscoelastic-viscoplastic model for short-fibre reinforced polymers with complex fibre orientations

This paper presents an innovative approach for the modelling of viscous behaviour of short-fibre reinforced composites (SFRC) with complex distributions of fibre orientations and for a wide range of strain rates. As an alternative to more complex homogenisation methods, the model is based on an additive decomposition of the state potential for the computation of composite’s macroscopic behaviour. Thus, the composite material is seen as the assembly of a matrix medium and several linear elastic fibre media. The division of short fibres into several families means that complex distributions of orientation or random orientation can be easily modelled. The matrix behaviour is strain-rate sensitive, i.e. viscoelastic and/or viscoplastic. Viscoelastic constitutive laws are based on a generalised linear Maxwell model and the modelling of the viscoplasticity is based on an overstress approach. The model is tested for the case of a polypropylene reinforced with short-glass fibres with distributed orientations and subjected to uniaxial tensile tests, in different loading directions and under different strain rates. Results demonstrate the efficiency of the model over a wide range of strain rates

A viscoelastic-viscoplastic model for short-fibre reinforced polymers with complex fibre orientations

This paper presents an innovative approach for the modelling of viscous behaviour of short-fibre reinforced composites (SFRC) with complex distributions of fibre orientations and for a wide range of strain rates. As an alternative to more complex homogenisation methods, the model is based on an additive decomposition of the state potential for the computation of composite’s macroscopic behaviour. Thus, the composite material is seen as the assembly of a matrix medium and several linear elastic fibre media. The division of short fibres into several families means that complex distributions of orientation or random orientation can be easily modelled. The matrix behaviour is strain-rate sensitive, i.e. viscoelastic and/or viscoplastic. Viscoelastic constitutive laws are based on a generalised linear Maxwell model and the modelling of the viscoplasticity is based on an overstress approach. The model is tested for the case of a polypropylene reinforced with short-glass fibres with distributed orientations and subjected to uniaxial tensile tests, in different loading directions and under different strain rates. Results demonstrate the efficiency of the model over a wide range of strain rates

Influence of clay addition on the properties of olive oil in water emulsions

International audienceThe behaviour of olive oil-in-water emulsions (O/W) was studied in the presence of smectite particles. The distribution of these particles in the emulsions and the effect of their interaction with the surfactant on the stability of the emulsions were investigated. Whereas the variation of surfactant and/or clay content did not seem to affect the nature of the emulsion, it had a significant influence on emulsion stability. This observation led to two main assumptions on the distribution of clay particles within the emulsion, either exclusively in the continuous phase, or also at the oil-water interface. In the absence of clay, the variation of surfactant concentration (from 0 to 17% (w/w)) allowed to distinguish 3 domains. In the first concentration domain (0-4.2%) emulsions stability increased with the content of surfactant. Within the second domain (4.2-8.5% (w/w)), a slight decrease in stability was observed due to flocculation by depletion. For surfactant concentrations equal or higher than 8.5% (3rd domain), emulsion stability increased sharply, probably due to the development of interactions between surfactant molecules as they came closer to their gelling concentration. The effect of clay addition to the aqueous phase (up to 10% (w/w)) on the physicochemical properties of the studied emulsions was assessed from stability, drop size, interfacial tension, rheological and acido-basic analyses. A model based on the location of clay particles either in the bulk or at the interface could be proposed, in which clay particles would interact with surfactant molecules in the bulk phase, and form a mechanical barrier around the oil droplets, thus increasing emulsion stability

Gemini surfactants of the type 1,2-ethanediyl bis-(dimethylalkylammonium bromide)

Gemini surfactants in the series 1,2-ethanediyl bis-(dimethyl-alkylammonium bromide), referred to as (n-2-n), were synthesized, purified and characterized by elemental analysis, 1H NMR, 13C and mass spectra. The thermodynamic properties of aqueous solutions of these surfactants were studied by different techniques. Thus, for gemini (10-2-10), cryoscopic osmometry was used to determine the c.m.c. and osmotic coefficient. By density measurement, the c.m.c., molar volume at the c.m.c. and the volume change during micellization were determined. Gemini (10-2-10) and higher homologs (12-2-12) and (14-2-14) were also investigated by electrical conductivity and surface tension measurements. Electrical conductivity measurements were used to determine their c.m.c. and degree of ionization. From surface tension versus log (molar concentration), we determined the c.m.c., surface tension at the c.m.c. (γc.m.c.), pC20 (negative log of the surfactant's molar concentration, C20, required to reduce the surface tension by 20 mN/m). The surface excess (Γmax) at the air/aqueous solution interface, the minimum area per surfactant molecule at the air/aqueous solution interface (A0) and the critical packing parameter (CPP) were then calculated. Surface tension measurements show that while the alkyl chain affects the critical micellar concentration it has little effect on the area per molecule at the air/water interface. The inhibitive effect of these compounds on the corrosion of iron in hydrochloric acid was also studied using gravimetric and electrochemical impedance spectroscopy. The results obtained show that these compounds are good inhibitors of iron corrosion and reach their maximum inhibition efficiency near their critical micellar concentration.Peer reviewe