Drying processes in the presence of temperature gradients --Pore-scale modelling

The European Physical Journal E - The influence of temperature gradients on the drying of water-saturated porous networks has been studied. We have focussed on the influence of the temperature on...     

Quasi-static liquid-air drainage in narrow channels with variations in the gap

This paper studies the shape of an air bubble quasi-statically flowing in the longitudinal direction of narrow channels. Two bottom topographies are treated, i.e., linear and quadratic variations of the gap along the transverse direction. This work analyses the main characteristics of the gas-liquid interface with respect to the wedge aspect ratio. From the convergence of asymptotic, numerical and experimental analyses, we found simple dependences for the finger width and total curvature as a function of channel aspect ratio. These results provide simple and general expressions for the pressure drop needed to overcome capillary forces and push the air finger inside the channel.     

Enhanced method performances for conventional and chiral CE-ESI/MS analyses in plasma

Due to its high efficiency, selectivity, and sensitivity, CE-ESI/MS has evolved as an efficient technique for the drugs and metabolites analysis in biological matrices. However, a sample preparation is mandatory prior to CE-ESI/MS analysis. To achieve fast and simplified sample preparation of plasma samples, protein precipitation (PP) and liquid-liquid extraction (LLE) were used with two injection techniques: hydrodynamic (HD) and electrokinetic (EK) injection. CE-ESI/MS analyses of pharmaceutical compounds and amphetamine derivatives were developed. Detection limits of 1 ppm were reached with PP and HD injection whereas 1 ppb was detected when samples were prepared with LLE and injected by EK. Same experiments were performed for stereoselective determinations in partial-filling mode and detection limits achieved were equivalent to conventional analysis (0.5 ppb per enantiomer). When complex matrices are analyzed, MS signal suppression or enhancement effects are generally not reproducible and could compromise results with ESI. Therefore, matrix effect was investigated in CE-ESI/MS with a commercially available coaxial sheath-liquid ESI interface used as postcapillary infusion system to determine MS signal alterations. Matrix effects were differentially evidenced according to the selected sample preparation. With PP, signal suppression was observed out of the analyses migration window, while for LLE no relevant matrix effect occurred in all experiments.     

Antibiotics in food: Legislation and validation of analytical methodologies

In this paper, European food safety legislation is presented, and special attention is devoted to monitoring residues of veterinary drugs in foodstuffs of animal origin. After a short review of the state of the art of analytical methodology for antibiotic residue analysis, the paper focuses on validation of analytical methods, with Decision 657/2002/EC as reference document. Finally, the main issues of the quality control of the analytical data, i.e. analysis of reference materials and participation in proficiency tests, are briefly addressed.     

Functionalized Biomimetic Magnetic Nanoparticles as Effective Nanocarriers for Targeted Chemotherapy

Novel MamC‐mediated biomimetic magnetic nanoparticles (BMNPs) are proposed as valuable carriers for targeted chemotherapy because of the size (36 ± 12 nm) and of surface properties conferred by MamC coating. They are super‐paramagnetic at room and body temperatures, have a large magnetic moment per particle, mediate hyperthermia, are cytocompatible, and, having a negative surface charge at physiological pH, can be efficiently coupled with DOXOrubicin (DOXO) and a monoclonal antibody (mAb) directed against the human Met/hepatocyte growth factor receptor (overexpressed in many cancers) displaying coupling stability, while releasing DOXO at acidic pH. This release can be enhanced by hyperthermia. The DOXO‐mAb‐BMNPs selectively recognize Met, bind efficiently to Met⁺ tumor cells, and discharge DOXO within their nuclei more efficiently than DOXO‐BMNPs, exerting cytotoxicity. These data represent proof of concept for future in vivo experiments in which the controlled dual targeting (mAb‐mediated and magnetic) approach and combined (chemotherapy and hyperthermia) therapy will be studied.     

Comparison of two methods of treatment for intraluminal thermal ablation using an ultrasound cylindrical phased array

Intraluminal (within the alimentary tract) thermal surgery has been shown to be a useful therapeutic option when extracorporeal focused ultrasound applicators cannot be used since their beam may not reach the target site. If plane transducers are used for the treatment of alimentary tract tumours, the applicator must be rotated in order to generate a cylindrical volume of necrosis. However, rotating these applicators and controlling their shooting direction presents technical difficulties. If tubular transducers are used it is difficult to treat arbitrary angles with a large therapeutic length. To solve these difficulties, the feasibility of an ultrasound phased array applicator has been evaluated using a cylindrical prototype (outer diameter 10.6 mm), which is composed of 16 elementary transducers working at 4.55 MHz and arranged on a quarter of the cylinder. Using this applicator it is possible to generate plane or cylindrical waves. Plane waves were generated by exciting eight successive elements of the array with appropriate delay times. The exposure direction was changed by exciting a different set of eight elements. In this way, the ultrasound beam was electronically rotated through the tissues. Cylindrical waves were generated by exciting several transducers without delay times. Imaging was provided using a miniature echographic probe. Ex vivo experiments were carried out in pig liver to compare two approaches of treatment. The first consisted of generating successive plane waves separated from each other by a 6 degrees angle. The second one consisted of exciting all the 16 elements without delay times. In the two cases, the lesions were well-defined and occupied a quarter of cylinder. In both sets of experiments, the sonication time and the intensity were 20 s and 17 W/cm(2), respectively. In the first case, the depth was up to 17 mm compared to 6 mm in the second case.     

The feasibility of constructing a cylindrical array with a plane rotating beam for interstitial thermal surgery

Thermal surgery has been shown to be a useful therapeutic option when external ultrasound applicators cannot be used as their beam will not reach the target site. If plane transducers are used, the ultrasound beam has to be rotated in order to generate a sufficiently large volume of necrosis. However, rotating deep-seated interstitial applicators and controlling their shooting direction presents major technical problems. The purpose of this study is to evaluate the feasibility of constructing a cylindrical array with a plane rotating beam for ablating esophageal tumors by interstitial hyperthermia. The feasibility of such an array has been initially evaluated using a plane array (which is easier to make from a technical point of view). This array was made with a new piezoelectric material because its mechanical properties make it ideal for the construction of a cylindrical array in the future. We showed that the beam of each array element is sufficiently divergent and that cross-coupling is small enough to generate a plane wave from a cylindrical array. In addition, power tests and electro-acoustic efficiency measurements demonstrated that the output was sufficient to induce tissue necrosis in the relevant conditions.     

A possible interpretation of atomic valency as a spontaneously broken symmetry response

The concept of atomic valency is looked at as a specific response of an atomic system to an arbitrary environment. It is shown, on the basis of a mathematical result in group actions theory, how valency might be related both to previously found Hartree–Fock deformed states and to the isotropy groups (up to a conjugation) of the extrema of the electronic energy functional.     

Two‐color operation of a free‐electron laser with a tilted beam

With the successful operation of free‐electron lasers (FELs) as user facilities there has been a growing demand for experiments with two photon pulses with variable photon energy and time separation. A configuration of an undulator with variable‐gap control and a delaying chicane in the middle of the beamline is proposed. An injected electron beam with a transverse tilt will only yield FEL radiation for the parts which are close to the undulator axis. This allows, after re‐aligning and delaying the electron beam, a different part of the bunch to be used to produce a second FEL pulse. This method offers independent control in photon energy and delay. For the parameters of the soft X‐ray beamline Athos at the SwissFEL facility the photon energy tuning range is a factor of five with an adjustable delay between the two pulses from ?50 to 950 fs.