Pneumatic capillary gun for ballistic delivery of microparticles

A pneumatic gun for ballistic delivery of microparticles to soft targets is proposed and demonstrated. The particles are accelerated by a high speed flow of Helium in a capillary tube. Vacuum suction applied to a concentric, larger diameter tube is used to divert substantially all of the flow of Helium from the gun nozzle, thereby preventing the gas from hitting and damaging the target. Speed of ejection of micron-sized gold particles from the gun nozzle, and their depth of penetration into agarose gels are reported.Comment: 7 pages, 3 figure

Caractérisation d'un procédé de dépôt de couches minces basé sur l'injection d'un aérosol dans un plasma à basse pression

Le dépôt chimique en phase vapeur assisté par plasma hors équilibre thermodynamique est largement étudié pour la synthèse de couches minces fonctionnelles. Pour certaines applications, la multifonctionnalité est un prérequis, ce qui peut être réalisé à l’aide d’un certain nombre de méthodes, dont le dépôt par plasma de couches minces nanocomposites. En utilisant un réacteurinjecteur, des précurseurs liquides avec ou sans nanoobjets peuvent être injectés dans la décharge sous la forme d’aérosols en régime pulsé, ce qui donne lieu à des plasmas transitoires avec des propriétés fondamentales qui dépendent du temps. L’impact de l’injection de pulses d’argon dans un plasma RF d’argon à basse pression a récemment été étudié par spectroscopie d’émission optique. La présente étude s’inscrit comme une suite à ce travail et vise à caractériser le procédé en présence de pulses de pentane pour le dépôt de couches minces hydrocarbonées, d’une part, et de pulses de pentane et de nanoparticules d’oxyde de zinc pour le dépôt de couches minces hydrocarbonées avec des nanoinclusions d’oxyde métallique, d’autre part. Dans la première partie, les résultats montrent que l’augmentation de la quantité d’aérosol injectée dans le plasma RF d’argon, obtenue en augmentant soit la fréquence des impulsions, soit la quantité de liquide injectée pendant une impulsion, influence différemment les variations transitoires de la pression d’opération et de la tension d’auto-polarisation sur le substrat pendant chaque impulsion. Dans la gamme des conditions expérimentales étudiées, la vitesse de dépôt des revêtements CxHy augmente avec la quantité de précurseur injecté. Cependant, en corrélant ces données avec les caractéristiques de l’aérosol obtenue par diffusion de la lumière, il s’avère que la taille des gouttelettes joue un rôle important dans la cinétique du dépôt et dans l’évolution des propriétés des couches déposées. Dans la seconde partie, les données montrent que des couches minces formées de nanoparticules de ZnO imbriquées dans une matrice CxHy peuvent être formées en remplaçant le pentane par une solution colloïdale. Dans ces conditions, la vitesse de dépôt et la quantité de nanoparticules injectées dans la couche peuvent être contrôlée en ajustant la fréquence des impulsions et la quantité de précurseur injectée pendant une impulsion.Plasma-enhanced chemical vapor deposition in non-equilibrium plasmas is widely studied for the synthesis of functional thin films. For some applications, multifunctionality is a prerequisite, which can be achieved using several methods, including plasma deposition of nanocomposite thin films. Using a reactor-injector, liquid precursors with or without nanoobjects can be injected into the discharge as pulsed aerosols, giving rise to transient plasmas with time-dependent fundamental properties. The impact of injecting argon pulses into a low-pressure RF argon plasma has recently been studied by optical emission spectroscopy. The present study is a follow-up to this work and aims to characterize the process in the presence of pentane pulses for the deposition of thin hydrocarbon layers, on the one hand, and pentane pulses and zinc oxide nanoparticles for the deposition of thin hydrocarbon layers with metal oxide nanoinclusions, on the other hand. In the first part, the results show that increasing the amount of aerosol injected into the RF argon plasma, obtained by increasing either the pulse frequency or the amount of liquid injected during a pulse, influences differently the temporal variations of the operating pressure and self-bias voltage on the substrate during each pulse. In the range of experimental conditions studied, the deposition rate of CxHy coatings increases with the amount of precursor injected. However, by correlating these data with the characteristics of the aerosol obtained by light scattering, it turns out that the size of the droplets plays an important role on the thin-film deposition kinetics and on the evolution of the properties of the plasma-deposited layers. In the second part, the data show that thin films formed of ZnO nanoparticles embedded in a CxHy matrix can be formed by replacing pentane with a colloidal solution. Under these conditions, the deposition rate and the quantity of nanoparticles injected into the layer can be controlled by adjusting the frequency of the pulses and the quantity of precursor injected during a pulse

Multiple Redox Modes in the Reversible Lithiation of High-Capacity, Peierls-Distorted Vanadium Sulfide.

This is the author accepted manuscript. The final version is available from ACS via http://dx.doi.org/10.1021/jacs.5b03395Vanadium sulfide VS4 in the patronite mineral structure is a linear chain compound comprising vanadium atoms coordinated by disulfide anions [S2](2-). (51)V NMR shows that the material, despite having V formally in the d(1) configuration, is diamagnetic, suggesting potential dimerization through metal-metal bonding associated with a Peierls distortion of the linear chains. This is supported by density functional calculations, and is also consistent with the observed alternation in V-V distances of 2.8 and 3.2 Å along the chains. Partial lithiation results in reduction of the disulfide ions to sulfide S(2-), via an internal redox process whereby an electron from V(4+) is transferred to [S2](2-) resulting in oxidation of V(4+) to V(5+) and reduction of the [S2](2-) to S(2-) to form Li3VS4 containing tetrahedral [VS4](3-) anions. On further lithiation this is followed by reduction of the V(5+) in Li3VS4 to form Li3+xVS4 (x = 0.5-1), a mixed valent V(4+)/V(5+) compound. Eventually reduction to Li2S plus elemental V occurs. Despite the complex redox processes involving both the cation and the anion occurring in this material, the system is found to be partially reversible between 0 and 3 V. The unusual redox processes in this system are elucidated using a suite of short-range characterization tools including (51)V nuclear magnetic resonance spectroscopy (NMR), S K-edge X-ray absorption near edge spectroscopy (XANES), and pair distribution function (PDF) analysis of X-ray data.SB acknowledges Schlumberger Stichting Fund and European Research Council (EU ERC) for funding. JC thanks BK21 plus project of Korea. We thank Phoebe Allan and Andrew J. Morris, University of Cambridge, for useful discussions. We also thank Trudy Bolin and Tianpin Wu of Beamline 9-BM, Argonne National Laboratory for help with XANES measurements. The DFT calculations were performed at the UCSB Center for Scientific Computing at UC Santa Barbara, supported by the California Nanosystems Institute (NSF CNS-0960316), Hewlett-Packard, and the Materials Research Laboratory (DMR-1121053). This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357

Conductivité électrique des verres et fontes d'oxydes (effet de l'incorporation de particules de RuO2)

MONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

Quels sont les leviers d'amélioration du management de la force de vante ? (pilotage et outils marketing. Application aux industries pharmaceutiques spécialisées en médecine esthétique)

AIX-MARSEILLE2-BU Pharmacie (130552105) / SudocSudocFranceF

La prévention : des aspects contradictoires (Commentaire)

Chaskiel Patrick, Sibille-Villeval Marie-Claire, Simonnet Claire. La prévention : des aspects contradictoires (Commentaire). In: Sciences sociales et santé. Volume 1, n°1, 1982. pp. 46-54

Localized RNAi and Ectopic Gene Expression in the Medicinal Leech

In this video, we show the use of a pneumatic capillary gun for the accurate biolistic delivery of reagents into live tissue. We use the procedure to perturb gene expression patterns in selected segments of leech embryos, leaving the untreated segments as internal controls

Ultrafast microfluidic mixer with three-dimensional flow focusing for studies of biochemical kinetics

Studies of the kinetics of biochemical reactions, especially of folding of proteins and RNA, are important for understanding the function of biomolecules and processes in live cells. Many biochemical reactions occur rapidly and thus need to be triggered on very short time scales for their kinetics to be studied, which is often accomplished by mixing in a turbulent flow. More rapid and sample-efficient mixing is achieved in laminar flow in a microfluidic device, in which the sample is two-dimensionally (2D) focused to a thin sheet. Here we describe the design and operation of an ultrafast microfluidic mixer with three-dimensional (3D) flow focusing. The confinement of a 3D-focused sample to a narrow stream near the middle of a microchannel renders its velocity nearly uniform and makes it possible to monitor the reaction kinetics without exclusion of any parts of the sample. Hence, the sample consumption is substantially reduced and the fluorescence of the sample can be monitored without a confocal setup. Moreover, the 3D-focusing allows facile measurements of velocity of the sample with a high spatial resolution using a specially developed technique based on epi-fluorescence imaging. The data on the velocity vs. position are used to precisely calibrate the conversion between position and the reaction time, which is essential for accurate kinetic measurements. The device performs mixing on a 10 µs scale, which is comparable to that of the laminar mixers with 2D focusing. Unlike previous ultrafast laminar mixers, which were machined in hard materials, the present microfluidic device is made of a single cast of poly(dimethylsiloxane), PDMS, and is thus simpler and less expensive to manufacture

Thorium oxide dissolution in HNO3_3-HF mixture: kinetics and mechanism

International audienceThis paper is an attempt to find out thorium oxide dissolution mechanism in HNO3-HF mixture. In a previous paper, several parameters effects on thorium oxide dissolution have been described, with specific focus on hydrofluoric acid effect, which can lead to an increase of the dissolution rate if present in small amount, but precipitates as ThF4 at higher content. Based on this previous study, experimental data were fitted using several dissolution models in order to find out the best one. Finally, a revisited model based on literature and considering the ThF4 formation was proposed. It describes the main steps of dissolution and is able to fit the experimental data for a wide range of solution compositions. This point is crucial since it allows considering an extrapolation of the established model to not-yet-studied conditions