Critères influençant le choix du premier poste après l'internat de chirurgie orale en France.

INTRODUCTION: The Specialized Diploma in Oral Surgery (Diplôme d’études spécialisées en chirurgie orale) was established in 2011. It gives its holders a unique combination of medical and surgical expertise. As a specialty, oral surgery can be pursued via both medical and dental pathways. However, the criteria guiding students’ choice of first job after residency remain largely unknown. PURPOSE OF THE RESEARCH: The primary objective was to evaluate the factors influencing students’ choice of first job after completing their oral surgery residency. RESULTS: The main geographical factors influencing job choice were the presence of family or friends, a short commute, and the location of the spouse’s place of work. Key practice conditions included access to advanced technical facilities and an operating theater offering general anesthesia. Clinical activities ranged from pre-implant grafts to general oral surgery. The likelihood of pursuing a hospital-based position in the same facility was correlated with the well-being experienced during the residency (p < 0.05) and with the oral surgeons’ medical background (p = 0.001). Significant associations exist between region of origin, internship location, and practice region (p < 0.001; p <0.001). CONCLUSIONS: The main factors influencing the choice of first position after oral surgery residency depend on family-related and technical criteria.

Synthesis and cell-free cloning of DNA libraries using programmable microfluidics.

Microfluidics may revolutionize our ability to write synthetic DNA by addressing several fundamental limitations associated with generating novel genetic constructs. Here we report the first de novo synthesis and cell-free cloning of custom DNA libraries in sub-microliter reaction droplets using programmable digital microfluidics. Specifically, we developed Programmable Order Polymerization (POP), Microfluidic Combinatorial Assembly of DNA (M-CAD) and Microfluidic In-vitro Cloning (MIC) and applied them to de novo synthesis, combinatorial assembly and cell-free cloning of genes, respectively. Proof-of-concept for these methods was demonstrated by programming an autonomous microfluidic system to construct and clone libraries of yeast ribosome binding sites and bacterial Azurine, which were then retrieved in individual droplets and validated. The ability to rapidly and robustly generate designer DNA molecules in an autonomous manner should have wide application in biological research and development.

The dynamics and stability of lubricating oil films during droplet transport by electrowetting in microfluidic devices.

The operation of digital microfluidic devices with water droplets manipulated by electrowetting is critically dependent on the static and dynamic stability and lubrication properties of the oil films that separate the droplets from the solid surfaces. The factors determining the stability of the films and preventing surface fouling in such systems are not yet thoroughly understood and were experimentally investigated in this study. The experiments were performed using a standard digital microfluidic cartridge in which water droplets enclosed in a thin, oil-filled gap were transported over an array of electrodes. Stable, continuous oil films separated the droplets from the surfaces when the droplets were stationary. During droplet transport, capillary waves formed in the films on the electrode surfaces as the oil menisci receded. The waves evolved into dome-shaped oil lenses. Droplet deformation and oil displacement caused the films at the surface opposite the electrode array to transform into dimples of oil trapped over the centers of the droplets. Lower actuation voltages were associated with slower film thinning and formation of fewer, but larger, oil lenses. Lower ac frequencies induced oscillations in the droplets that caused the films to rupture. Films were also destabilized by addition of surfactants to the oil or droplet phases. Such a comprehensive understanding of the oil film behavior will enable more robust electrowetting-actuated lab-on-a-chip devices through prevention of loss of species from droplets and contamination of surfaces at points where films may break.

Macro to microfluidics system for biological environmental monitoring.

Biological environmental monitoring (BEM) is a growing field of research which challenges both microfluidics and system automation. The aim is to develop a transportable system with analysis throughput which satisfies the requirements: (i) fully autonomous, (ii) complete protocol integration from sample collection to final analysis, (iii) detection of diluted molecules or biological species in a large real life environmental sample volume, (iv) robustness and (v) flexibility and versatility. This paper discusses all these specifications in order to define an original fluidic architecture based on three connected modules, a sampling module, a sample preparation module and a detection module. The sample preparation module highly concentrates on the pathogens present in a few mL samples of complex and unknown solutions and purifies the pathogens' nucleic acids into a few µL of a controlled buffer. To do so, a two-step concentration protocol based on magnetic beads is automated in a reusable macro-to-micro fluidic system. The detection module is a PCR based miniaturized platform using digital microfluidics, where reactions are performed in 64 nL droplets handled by electrowetting on dielectric (EWOD) actuation. The design and manufacture of the two modules are reported as well as their respective performances. To demonstrate the integration of the complete protocol in the same system, first results of pathogen detection are shown.

Gas-liquid selective oxidations with oxygen under explosive conditions in a micro-structured reactor.

The gas-liquid oxidation of cyclohexane is performed at high temperature (>200 degrees C) and pressure (up to 25 bar) using pure oxygen in a Pyrex capped silicon etched microreactor which allows convenient screen reaction conditions well above the flammability limit.

Opto-electronic DNA chip-based integrated card for clinical diagnostics.

Clinical diagnostics is one of the most promising applications for microfluidic lab-on-a-chip or lab-on-card systems. DNA chips, which provide multiparametric data, are privileged tools for genomic analysis. However, automation of molecular biology protocol and use of these DNA chips in fully integrated systems remains a great challenge. Simplicity of chip and/or card/instrument interfaces is amongst the most critical issues to be addressed. Indeed, current detection systems for DNA chip reading are often complex, expensive, bulky and even limited in terms of sensitivity or accuracy. Furthermore, for liquid handling in the lab-on-cards, many devices use complex and bulky systems, either to directly manipulate fluids, or to ensure pneumatic or mechanical control of integrated valves. All these drawbacks prevent or limit the use of DNA-chip-based integrated systems, for point-of-care testing or as a routine diagnostics tool. We present here a DNA-chip-based protocol integration on a plastic card for clinical diagnostics applications including: (1) an opto-electronic DNA-chip, (2) fluid handling using electrically activated embedded pyrotechnic microvalves with closing/opening functions. We demonstrate both fluidic and electric packaging of the optoelectronic DNA chip without major alteration of its electronical and biological functionalities, and fluid control using novel electrically activable pyrotechnic microvalves. Finally, we suggest a complete design of a card dedicated to automation of a complex biological protocol with a fully electrical fluid handling and DNA chip reading.

Electrical detection of DNA hybridization based on enzymatic accumulation confined in nanodroplets.

Electrical monitoring of DNA hybridization is one way to reduce the cost and size of the DNA chip reader in comparison with the more classical optical detection. Within electrical methods, electrochemical detection shows very high performances in terms of accuracy and sensitivity, especially when an enzymatic accumulation is used to amplify the signal. However, signal multiplexing for miniaturized systems based on both enzymatic accumulation and electrochemical detection remains challenging due to the Brownian diffusion of the detected product of the enzymatic reaction. We present here a DNA chip with electrical detection based on the following sequence: (i) hybridization of nucleic acids and washing in a liquid layer as usual, (ii) formation of independent nanodroplets on each detection site, (iii) enzymatic accumulation in each droplet avoiding cross-contamination between neighboring sites, and (iv) electrochemical detection of the product accumulated during the enzymatic reaction. The simple and fast transition from the liquid layer (hybridization step) to an array of nanodroplets (enzymatic accumulation and detection steps) was performed through the filling of the hybridization chamber with a solution containing the enzymatic substrates, the drawing of this solution, and the simultaneous creation of droplets thanks to retention areas based on circular rims or hydrophilic rings. Using this approach, hybridization is achieved in a liquid layer as usual, followed by the enzymatic accumulation in nanodroplets to avoid the cross-talk between neighboring sites. Moreover, working in droplets enables a fast increase in the concentration of the product generated by the enzymatic reaction and thus an improvement of the detection limit of the system.