Understanding soft matter mechanical behavior is of great interest as multiphasic combinations of their composition induce new properties which can be exploited for innovative applications. However, the final features optimization requires a tight multiscale control of the structure, even during the elaboration early stages. This paper presents a multifrequency technique to investigate this evolution at mesoscopic scale and its bonds with other scales. A TMS resonator is used as a discrete spectral ultrasonic microrheometer from 5MHz to 50MHz. Then, soft matter can be described as an elastic structure, due to macromolecular interactions, immersed in an effective viscous fluid. An original model of the measured mechanical impedance is proposed and enables the simultaneous monitoring of the effective viscosity and the internal structure. It is based on fractional calculus. In addition to complex shear modulus, the evolution of a fractional parameter, ranging from zero for solids to one for Newtonian fluids, can be studied. The model and the experimental set-up are validated with various complex materials: Newtonian glycerol mixtures, cosmetic emulsions, and silica gels. Effective viscosity accuracy is demonstrated (less than 5% of error for Newtonian fluids). Structural values of complex fluids range from 0.6 (gels) to 1 (liquids). The extracted structural parameter can be linked to the fractal dimension. Hence, this technique is relevant to describe soft matter structure. Moreover, the structural parameter on-line monitoring can be useful to optimize the elaboration process of new products. Indeed, a microscopic characteristic time can be extracted and correlated to the macroscopic gelation time.

Background: New biosensor techniques allowing detection of low concentrated substances show a great variety nowadays. The construction of a system with modified quartz as a part of a Quartz Crystal Microbalance (QCM) techniques helps the detection and confirmation of low toxin concentrations in a sample. Objective: The study aims to allow the application of methods for preparation and modification of the gold surface of piezoelectric crystal for detection of aflatoxin B1(AFB1) in the concentration range 0.2 - 2.0 µg/L by QCM technique (quartz - crystal microbalance). Methods: The procedure for the preparation of quartz crystal sensors for experimental purposes was performed. The quartz surface was activated and covered with self-assembled monolayer to immobilize antibody (rabbit anti-aflatoxin B1) for the detection of antigen - antibody reaction. Results: The G” corresponds to viscous properties of the material, during applied deformation of the material in the presence of different concentrations, which revealed in the sensitivity of the used resonator. Conclusion: Detection of toxic pollutants may be achieved via QCM methods, ultrasound resonator and piezoelectric quartz techniques for measurement. These techniques allow detection of significantly low concentrations of toxic pollutants, in particular, AFB1, compared to analysis with direct and indirect ELISA immunoassays.

To carry out our study, standard cream's models were formulated changing Oil/Water ratio and emulsifier's concentration. The droplets organization and behavior of these complex preparations were compared with viscoelastic parameters measured at microscopic scale using High Frequency rheology. Microscopy and granulometry measurements were used to determine droplets organization in the aqueous phase of emulsions to complete this study.

The evolution of the elastic and thermal properties of a tetramethylorthosilicate (TMOS)-based gel that exhibits an extraordinary ringing effect when enclosed in a bottle is investigated during the sol-gel transition. The results demonstrate the feasibility of three proposed experimental methods for monitoring of gels during their formation. The shear stiffening evolution during gelation is monitored by ringing bottle, resonant acoustic spectroscopy and by an ultrasonic technique using piezo electric excitation and detection. The evolution of the longitudinal modulus and the thermal diffusivity of the gel during stiffening are simultaneously determined by a combined photoacoustic and photothermal method based on heterodyne diffraction detection of impulsive stimulated scattering by, respectively, a propagating acoustic wave grating and a decaying thermal expansion grating that were both thermo elastically generated using a pulsed laser. Also, the feasibility of an inverse photopyroelectric method and a hot ball technique to monitor the thermal transport efficiency and thermal impedance of a forming gel by tracking the thermal conductivity, the thermal diffusivity, and the thermal effusivity is demonstrated. The network polymerization and stiffening during the sol-gel transition in TMOS-gel corresponds with substantial changes in the shear acoustic velocity and in all thermal properties, while the longitudinal acoustic velocity is only weakly affected.

Hyaluronic acid (HA) is present in almost all biological fluids and tissues. The chemical HA structure is described as a linear polysaccharide with a high molecular mass (about one MDa) formed from disaccharide units containing Nacetyl-d-glucosamine and glucuronic acid. This chemical structure ensures an excellent biocompatibility. In addition its viscoelastic properties are singularly appreciated in cosmetic products like moisturizing preparations, anti-wrinkle effect cream (for the elasticity restoration) [1], and skin protection against ultraviolet irradiation [2]. HA is usually produced from non-sustainable resource, or from genetically modified (GMO) bacteria, or from animal waste [3]. A novel method production of this high value product (more than 100 k€/kg [4]) had recently emerged based on microalgae production process [5]. In order to be competitive, users of this new manufacturing method need to assess in-line the quality of the product and if it possible use this information for product quality optimization. Electromagnetic sensors are well known in the food industry for reliability and quick quality assessment of hydrocarbon based food like wheat [6]. This paper reports some preliminary results on microalgae by product of an electromagnetic wideband radiofrequency sensor. This sensor consists of an open coaxial line cell filled with a liquid solution and impedance measurement of the cell is carried by an network analyzer at a temperature of 25°C. The microalgae studied where separated in two phases, a liquid one extracted directly from the reactor (MC) and a foam like extracted by an in-reactor skimmer (ME). In order to assess the sensibility of the measurement and simulate different production yield, extracted fraction MC and ME where diluted. These dilutions were carried with respectively microalgae nutriment solution (NS) and pure water in order to keep a constant ionic strength to achieve the low frequency conductivity constant and to avoid a measurement bias. The preliminary results show a good sensitivity of impedance vs HA microalgae concentration in the 1 MHz to 10 MHz range.

This work is related to the synthesis and characterization of new hybrid sol-gel materials. Several carriers based on poly (N-acryloylglycine) (NAGly) composed of poly (ethylene glycol) dimethacrylate (PEGDM) were prepared. The effectiveness of biofilms formation of bacterial strains Escherichia coli and Pseudomonas fluorescents on the matrices was investigated by biochemical methods. Two types of hybrid gels were synthesized based on PEGDM, 2-hydroxyethyl acrylate (HEA) and N-acryloxysuccinimide ester (NAS) with incorporation of inorganic precursors. The rheological properties of the gels and formed biofilms were investigated by quartz crystal microbalance (QCM). The experimental results demonstrated that the obtained matrices are appropriate for biofilms formation.

The sensing of dielectric properties of organic media is required in various fields such as agriculture, food industry or human health. Indeed these properties are related to the state of the organic media, and may be used as relevant indicators, especially in the radiofrequencies (RF), to either assess the quality of food in food industry or the physiopathological state of tissues in medical applications. As opposed to some conventional dielectric measurement techniques, the technique proposed in this study is contactless, easy to implement, and sensitive to both the conductivity and the permittivity of the media under investigation. The sensing technique lies in the distant monitoring of a high-quality factor inductive RF resonator, electromagnetically coupled to the investigated medium. In this study, the authors aim at assessing the feasibility and accuracy of dielectric media sensing by means of their contactless and easy-to-implement method. To that purpose, a wireless cylindrical inductive RF resonator inductively coupled to a monitoring bobbin coil is considered. It constitutes a radiating transmit and receive inductive sensor electromagnetically interacting with its direct environment (e.g. organic material). The dielectric properties of this environment are sensed through the impedance changes of the resonator, which is remotely monitored by a distant bobbin coil. In this study, the resonator is implemented for the distant sensing of organic material phantoms constituted of solutions featuring tabulated dielectric properties. A lumped element modeling of the RF probe interacting with the medium is proposed. Preliminary results open the way to the development of easy-to-implement dielectric characterization techniques of organic media, such as contactless medical sensing devices.

New TiO2-based hybrid materials composed of an organic polymer, cellulose acetate butyrate and copolymer of acrylonitrile acrylamide (AN + AA) were prepared. The effectiveness of immobilization of microbial strain Arthrobacter oxydans 1388 on the newly synthesized hybrid membranes was investigated by biochemical methods. The obtained results revealed that the matrix more suitable for biofilm formation was composed of organic polymers without a metal component in the membrane composition. The influence of Ni2+ on urease activity produced by biofilms was investigated. The experimental results demonstrated that 2 mg L-1 concentration of Ni2+ in the nutrient medium is more appropriate for biofilm proliferation.

Verdigris is a green copper organometallic pigment, widely used in paintings during the fifteenth and sixteenth centuries. With ageing, chromatic modifications like browning or darkening can be observed on those green painted layers. An original but crucial approach has been developed based on the characterization of a reference neutral verdigris pigment—anhydrous copper acetate—and model samples, made of verdigris and linseed oil. Samples have undergone artificial ageing (temperature, light) to reproduce the color change effect. They were analysed before and after accelerated ageing tests by a complementary set of classical techniques: colorimetry, electron paramagnetic resonance, X-ray absorption spectroscopy, and UV–visible absorption. Our experiments revealed that the incorporation of the verdigris pigment in linseed oil induces a transformation of the copper acetate bimetallic structure, with the formation of monomeric species. These monomers, however, are not directly responsible for the darkening. The chromatic alteration seems instead linked to the transient formation of Cu(I) in the copper complexes of the pigment/oil system. This formation could be initiated by ambient light absorption through ligand-to-metal charge transfer, which favors the decarboxylation of the copper complexes leading to the reduction of Cu(II) into Cu(I). Moreover, dioxygen can react with partially decarboxylated dimers to form peroxy-Cu dimer complexes that can be responsible for the darkening.

The biodegradation of aniline is of a great concern and has attracted many researchers’ attention. Because of its toxic and recalcitrant nature as well as the wide application of aniline containing chemicals, aniline is considered to be an increasing threat both to the environment and to human health. Microbial transformation and degradation are major mechanisms to eliminate aniline from the environment. Most of the microorganisms found in the nature, industrial and clinical environments are attached to a surface. The aim of this study is to synthesize new hybrid biocompatible materials, to investigate the obtained matrices for their ability to hold biofilm formation. It was report about comparison of the formation of biofilms from model gram-negative bacteria Pseudomonas species 1625 onto different, newly synthesized hybrid carriers. Some kinetic investigations on aniline biodegradation applying obtained biofilms are also discussed.

To incorporate microorganisms and to preserve their integrity, new matrices of poly( N ‐acryloylglycine) have been designed under appropriate conditions. To understand the interactions between the microorganisms and the organic part of the matrices, different conetworks of poly( N ‐acryloylglycine) have been synthesized and characterized. Copolymerization with two crosslinkers was performed with different compositions. The thermal and swelling properties of conetworks are specifically controlled and compared. These investigations show that the swelling ratio of these materials is compatible with the incorporation of biomolecules in these matrices. They successfully permit Pseudomonas species 1625 bacteria incorporation. The biological activity of bacteria is also preserved, allowing the use of these materials for innovative biological applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 835‐841, 2013