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Crystallization is one of the key steps for the determination of a protein structure by X-ray diffraction. Microfluidics offers new perspectives for high throughput screening of the crystallization conditions with much reduced cost. In particular, fast prototyping of microfluidic devices by soft-lithography using PDMS has lead to successful demonstrations of both on chip crystallisation and large scale integration. However, PDMS, which is gas permeable, can lead irreversibly to the liquid evaporation in microfluidic chambers. Because of the fragility of the protein crystals, this is clearly undesirable for post-crystallization experiments. We describe here a simple but yet efficient approach to solve this problem, where the PDMS device is placed inside a small tight box having two compartments separated with a thin membrane. Inside the box, a good control of humidity can be achieved and protein crystals could be conserved over a long period without dehydratation.

We report on a micro-fabrication method based on micro-aspiration assisted lithography (MAAL). Unlike nanoimprint lithography where a mould is pressed into a resist layer spin coated on a substrate, MAAL uses aspiration forces to guide the resist material in the mould cavities. By suing this technique, the limit of capillary based lithography techniques has been extended. Double layer PDMS moulds were fabricated using multi-layer soft-lithography in which a micro-aspiration network could be introduced close to the pattern layer of the mould. As a result, high resolution patterning could be obtained with a UV curable resist. We also show the results of patterning of a thin layer of PDMS, nano-particles as well as agar gels. We have also provided a semi-quantitative analysis in order to understand the limitation of different approaches.

This paper deals with a novel and flexible method for microfluidic device assembling. In general, microfluidic device assembly is obtained by irreversible sealing with anodic, thermal or chemical bonding. Reversible assembly can be obtained by aspiration through a crossing channel network (CCN) between the two pieces of microfluidic device (channels and substrate). In this way, relatively high injection pressure can be achieved in microfluidic channels without leakage. We describe the principle and the fabrication of such PDMS devices and also show two examples of the described assembly method applied to surface functionalization.

Electrocapillary force can be used to displace a mercury droplet confined in microfluidic channels. When the plug is moved into an area of a thin membrane of low Young's module, the surface tension of the confined mercury droplet provides a force to deform the membrane. We show that this effect, together with the electrocapillary force controlled movement, can be used for the actuation of microfluidic elements. We applied this technique to micro valves obtained by using multilayer soft-lithography techniques. Fabrication of integrated microelectrodes as well as single and multiple mercury plugs using microfluidic techniques has also been shown, thereby providing a set of technology for more detailed investigations.

Protein immobilization is of great importance for the development of biosensors, immunoassays and microfluidic devices. In this work, we study the in situ bio-functionalization and cell adhesion in microfluidic channels. A way of covalently linking antibodies on the channel surface while keeping their bio-functionality and its application for efficient cell adhesion were shown. Soft lithography has been used to fabricate simple microfluidic devices and all chemical and biologic materials were injected into microfluidic channels for the in situ bio-functionalization and cell adhesion. Our results show that the established bio-processing protocol significantly enhances the protein immobilization on both glass and poly-dimethylsiloxane surfaces, thereby allowing one to develop a large number of applications.

Ferrites have magnetic properties suitable for electronic applications, especially in the microwave range (circulators and isolators). Hexagonal ferrite, such as barium ferrite (BaFe12O19 or BaM), are of great interest for microwave device applications because of their large resistivity and high permeability at high frequencies. BaM films, 1–10 μm thick, were deposited under optimized conditions by RF magnetron sputtering on alumina and silicon substrates. After deposition, films were amorphous and needed a post-deposition annealing at 800 °C to crystallize and to present magnetic properties. X-ray diffraction (XRD) and scanning electron microscopy (SEM) results showed that BaM films deposited on alumina and silicon substrates presented a good crystallization, a smooth surface and no cracks. Ba, Fe and O depth profiles obtained by secondary ion mass spectroscopy (SIMS) showed that the films have a good in-depth uniformity. The film residual stress was evaluated using curvature measurements. Whatever the substrate type, the films are in compression after deposition. Upon annealing and crystallization, a tensile stress adds up in relation with crystalline arrangements. Finally, regarding the magnetic properties measured using a vibrating sample magnetometer (VSM), the optimized saturation magnetization of such films reached 500 mT and the coercive force 325 kA/m. These values are close to that of the bulk BaM.

Introduction La scoliose idiopathique de l’adolescent (SIA) est une deformation tridimentionnelle du rachis, d’etiologie inconnue. Nous posons l’hypothese pathogenique suivante : la SIA s’accompagne d’une representation centrale erronee de la verticalite a l’origine d’une adaptation posturale du tronc dans les 3 plans de l’espace. Pour le verifier, nous avons debute une etude dont l’objectif est d’evaluer le sens de la verticalite dans la SIA, a la fois dans ses composantes top down et bottom up . Materiel et methodes Trois types de mesure ont ete realisees : – Verticale visuelle subjective (VVS) realisee en conditions visuelles statique et dynamique (stimulation optocinetique 40°/sec) chez 83 SIA versus 15 controles non scoliotiques ; – Verticale posturale subjective (VPS) chez 12 SIA ; – evaluation de l’image du tronc deforme par le Spinal Appareance Questionnaire (SAQ) chez 19 SIA versus 5 hypercyphoses thoraciques. Resultats Exactement 51,8 % des SIA ont une VVS anormale, surtout en condition visuelle dynamique versus 0 % dans le groupe controle. Les valeurs de VPS dans la SIA sont proches de celles trouvees chez les hemiplegiques pusher (exemple : tilt droit = 8,28°4,05). Les SIA avec une scoliose majeure ont un SAQ significativement deteriore par rapport aux hypercyphoses thoraciques. Discussion–conclusion Un sous-groupe de patients SIA presente une perturbation du sens de la verticalite. Cette anomalie peut etre secondaire a la deformation scoliotique mais peut egalement etre un facteur d’evolutivite de la SIA.

The ring cavity device with large diffraction path in the free-space of the cavity cannotbe described within the mean-field model. It is shown to generate a large variety of monoconicaland multiconical patterns with wave and/or Turing modes, for anonlinear medium either made of two-level atoms or with a χ (2) crystal.Even in the limit of a single-longitudinal mode operation, monoconical structures can be differentfrom those predicted by the mean-field model. For instance, chaotic localized structures with anatomic medium and square patterns with a DOPO are presented.

International audience; We present a thermo-resistance based micro-calorimeter using a glass/platinum/PDMS prototyping technology which is more flexible than the existing silicon based technology for lab on a chip device integration. Resistance monitoring and fluid injection techniques are optimized in order to reduce thermal noises and improve the detection sensibility. We used neutralization acid-base reaction to evaluate the device capability in determination of both reagent concentration and reaction enthalpy. We also performed a glucose/glucose oxy-dase enzymatic reaction to illustrate the advantage of using PDMS device for the studies of aerobic reaction.

Investigations of the thermal drifts of the resistivity and gauge factors of polysilicon are needed to extend its use as a transducing material for high temperature piezoresistive microsensor applications. Longitudinal gauge factors of LPCVD B-doped and rapid thermal-annealed polysilicon films, patterned onto oxidized silicon using a clamped beam technique, have been measured in the 20–200 °C temperature range as a function of the doping concentration between 8 × 10 18 and 10 20 cm −3 . The gauge factors have been simulated as a function of the B-concentration and the temperature, starting from experimental data for the polysilicon resistivity and literature data for the hole resistivity and the piezoresistive effect in monocrystalline silicon. Only a model involving a significant piezoresistive effect at grain boundaries can adequately fit the temperature dependent gauge factors of polysilicon.

Silicon on insulator (SOI) pressure sensors show potential applications in high temperature environment. However, as a result of thermal mismatch, large stresses usually exist in the composite SiO 2 /Si membranes which would provide an otherwise promising substrate for such sensors. These stresses can significantly influence the long term reliability of such membranes. In this work a high spatial resolution (10 μm 2 ) Raman spectroscopy method has been used to measure the localized stresses over an oxidized membrane, thus yielding stress maps. The method is based on the frequency shift of the Raman line at 520 cm −1 . Shift between 0.05 and 1 cm −1 are observed. A three-dimensional commercially available finite element modeling (FEM) software (ANSYS) has been used to modelize the thermal stress distribution over the complete micromachined bilayer membrane. Its validity has been checked out through optical profilometer deflection measurements. The experimental Raman shifts were compared with those calculated using stresses from FEM and a biaxial stress hypothesis. Finally, the sensitivity of Raman stress mapping method for high temperature SOI pressure sensors is discussed.

The stability of the 8-fold orientational order quasipattern is studied both analytically and numerically. Close to the intensity threshold, the sequence, that minimizes the free energy, displays structures built up with four, two and one modes, successively, as the linear refractive index decreases. Differently, when increasing the intensity above the threshold, the 8-fold orientational order quasipattern bifurcates to a three mode quasiperiodic pattern, followed by a robust rhombic pattern. A multiconical emission process is invoked to explain the occurrence of the rhombuses.

Near-field patterns with three to fifteen petals set on a single circle are numerically observed in the ring cavity device. Three to six petal daisies result from usual finite size effects. We point out the non-trivial formation of seven to fifteen petal daisies, with a top-hat input, and a small diffusion term that controls this daisy-type pattern formation, preventing the usual hexagonal structure to be formed.

Flower-like patterns are numerically investigated when the schematic Rb four-level relevant transition is reduced to the lower two Zeeman sub-levels via the adiabatic elimination of the upper states. These flower-like patterns are the signature of small aspect ratio while typical patterns like squares are displayed in the opposite limit. Depending on the relative weights of diffraction effects and nonlinearities, they display, or not, self-similar shapes in the near and the far field.

A general method is presented for determining the average tensorial components of a physical quantity for a polycrystalline sample with random crystallite orientation, when this tensor is known for a monocrystal. The technique, based on the determination of the rotationally invariant part of the tensor, is very convenient and provides analytical results. Explicit expressions are given for symmetrical 4th rank and 8th rank tensors and are applied to calculate piezoresistive effects in polycrystalline silicon.

The formation of multi-petals and multi-spirals is analysed with the help of a generalized dispersion relation, taking advantage of the invariance of the rotation frequency of a pattern. It results in an eigenvalue problem, which allows us to predict the rotation frequency and the radial curvature of the pattern, in good agreement with exact calculations: A stationary pattern is predicted to look like petals, while a uniform rotating pattern is predicted to have some curvature, leading to a spiral shape.

We present numerical simulations of a simplified model for the ring cavity device in the case of round-trip time equal to the atomic radiative lifetime. Real pattern effects are of primordial importance, especially in small systems where the boundary conditions seem the key for the pattern selection. For a plane-wave input, our system displays not only hexagons, as in the mean-field model, but also stationary rolls, squares and octagons with a weakly chaotic structure. All these structures are also obtained in the case of bell-shaped input profile with large aspect ratio; they even appear regular and wonderful, as if boundary effects stabilize them.

The instability threshold characteristics are derived for the ring cavity with passive weakly absorbing two-level atoms cell. Emission of several conical shells is predicted, depending on the optical arrangement, and on the buffer gas pressure. In the case of pure vapor, each conical shell has its own frequency, while all the conical shells display the same frequency in case of large buffer gas pressure.

ObjectiveThe AIS is a three-dimensional deformation of the spine, frequent, potentially progressive, with unknown etiology. It is generally accepted as being multifactorial origin, including neurosensorial factors, with orthostatic postural control disorders. In particular, Assaiante et al. showed a selective impaired of the dynamic proprioceptive tract. However, the procedures used to establish this impaired are complex and require motion analysis laboratories, inaccessible in routine clinical practice. Our objective is to determine whether, by clinical equilibration tests, simple, realizable in routine care, it is possible to find the same result.MethodsA cross-sectional study comparing 114 adolescents with right thoracic AIS (including 94 girls, mean age: 14.5±1.9years, Cobb angle: 35.7±15.3°) with 81 matched non-scoliotic adolescents (including 69 girls, mean age: 14.1±1.9 years) was conducted between January 2013 and March 2015. Three clinical equilibration tests are performed: a dynamic test (Fukuda stepping test-Utenberger), two static tests (Romberg sensitized Support monopodal eyes closed).ResultsFor the static tests, no significant difference between the 2 groups. The difference is significant for the dynamic test, for the distance travelled (P

ObjectiveThe AIS is pathology with multifactorial origin. It affects between 1–3% of the population aged 10–16 years. Many authors suggest orthostatic postural control disorders in AIS. The orthostatic postural control is the ability to organize the standing posture on the earth-vertical. The longitudinal body axis, the trunk and the spinal axis are oriented in an internal representation of the gravitational vertical. Our hypothesis is that AIS is the consequence of a re-organization of orthostatic postural control, on an erroneous internal representation of earth-vertical. Our objective is to show a disturbance of the sense of verticality in the AIS, by measuring the Subjective Visual Vertical (SVV) in AIS, particularly in dynamic visual condition.MethodsProspective study: a group of adolescents with AIS versus a control group of non-scoliotic adolescents. The test is a measure of the SVV (Synapsis), standing posture, in static and dynamic visual conditions (visual disturbance by optokinetic stimulation 40°/sec). Six measures are evaluated. Norms for static condition–2.5° to +2.5°, and for dynamic condition–4 to +4°.ResultsPreliminary results on 35 scoliotic adolescents (Group S: 31 girls, 14.2±1.74 years, angle: 38.4±15.7°), versus 5 non-scoliotic adolescents (GroupC: 5 girls, 14.9±1.14 years). Group S: static VVS=1.59±1.45°; dynamic VVS=4.7±8.27°. 57.1% with a least 1 pathological value, 28.5% with a least 2 pathological values, particularly in dynamic visual condition (clockwise rotation with right tilt of the VVS, average 12.39°). Group C: static VVS=0.72±0.5°; dynamic VVS=2.17±1.5°. No subject control with pathological value.DiscussionThis preliminary study shows a disturbance in the vertical evaluation in the AIS. One possible explanation is a disturbance of the sense of verticality by impaired multisensory central integration.The authors are grateful to the Harps Association's members, for their helpful comments.

The Lyapunov analysis of low-dimensional instabilities in retarded differential systems predicts both the Hopf bifurcation thresholds and the fundamental frequencies. A demonstration is made in a saturable thin sample ring cavity.

Mated pairs of Mongolian gerbils were rejoined by two of their own young, one of each sex, after periods of separation starting when the young were four or seven weeks old and lasting either one or four weeks. An additional sub-group of litters was separated when six weeks old, for a period of separation of two weeks. In another group of mated-pairs, mated-adults were introduced and observed in the same way. Occurrences of sniffing, opposition and pursuit between each adult and each intruder was noted over a period of one hour. A clear effect of the sex of the resident adult on agonistic behaviour was evident. The adult female develops its agonistics acts sooner than the male i.e. it is more responsive than the male to a short duration of separation from the juveniles. The adult female shows either pursuit or opposition to juveniles but shows almost no agonistic behaviour in the presence of unrelated adults. As for the adult male, its agonistic acts begin to appear after four weeks of separation and persist with very frequent opposition, in adult-adult meetings. The sex of the intruder only appeared to be a significant factor after four weeks of separation. After four weeks of separation, opposition of the adult male to the young male was significantly higher than that to the young female. Sniffing of the young male by the adult female was significantly higher than that of the young female. With the same period of separation, but with opponents of eleven weeks, as well as in meetings of adults, each resident adult had a greater number of interactions with the intruder of the same sex.