Authors:L. Komunjer, M. Ollivon, B. Fouconnier, A-T Luong, I. Pezron, and D. Clausse
Trichlorofluoromethane (CCl3F) and water form clathrate hydrate which melts at 8.5 °C under atmospheric pressure. By DSC and X rays analysis we could
distinguish between hydrate and ice formed in emulsion containing NaCl and show that quantity of hydrate formed and its dissociation
temperature are dependent on solution concentration. The equilibrium curve hydrate-NaCl solution is displaced towards higher
temperatures with respect to corresponding ice curve. Consequently solid–liquid equilibrium can not be established in presence
of both solids. Growth of hydrate crystals at the expense of ice was evidenced. Role of salt in hydrate growth and ice melting
Emulsion counting, more correctly known as colloid counting, is the most widely practised technique for the radioassay of aqueous sample types by the liquid scintillation technique. The double ratio technique can be used to determine whether or not radioactivity is being counted with true solution efficiency, and was applied to a range of systems consisting of deionised water, Triton X-100 and toluene (containing3H-water,3H-toluene or14C-toluene). Some hypotheses were developed in an attempt to explain the double ratio values obtained for the various systems studied.
Authors:Piotr M. Korczyk, Monika E. Dolega, Slawomir Jakiela, Pawel Jankowski, Sylwia Makulska, and Piotr Garstecki
Conducting reactions in droplets in microfluidic chips offers several highly attractive characteristics, among others, increased yield and selectivity of chemical syntheses. The use of droplet microfluidic systems in synthetic chemistry is, however, hampered by the intrinsically small throughput of micrometric channels. Here, we verify experimentally the potential to increase throughput via an increase of the scale of the channels.We use the results of these experiments characterizing the processes of (1) generation of droplets, (2) mixing in droplets, (3) inter-phase extraction, and (4) the yield of synthesis of pyrrole, to postulate a number of guidelines for scaling up the throughput of microfluidic droplet systems. In particular, we suggest the rules for maximizing the throughput via an increase of the size of the channels and via parallelization to optimize the throughput of synthesis against the cost of fabrication of the chips and against the kinetic requirements of specific reactions.
Authors:L. Zane Miller, Jeremy L. Steinbacher, Tania I. Houjeiry, Ashley R. Longstreet, Kendra L. Woodberry, B. Frank Gupton, Banghao Chen, Ron Clark, and D. Tyler McQuade
Monodisperse silica microcapsules are typically fabricated using hard templating methods. Though soft templating methods are known, none yet provides a fast and easy method to produce monodisperse capsules. Herein, we describe a mesofluidic strategy whereby monodisperse droplets of reactive silica precursors are formed using a snap-off mechanism via a T junction. Both the mesofluidic system and the composition of the reactive silica formulation are critical features. Using solid- and solution-state 29Si nuclear magnetic resonance, scanning electron microscopy, and optical microscopy, we have developed models for why some formulations form exploding capsules, why some capsules contain crystalline materials, and why some capsules have thin or thick walls.
Authors:J. Gerard, C. Swanson, L. Ver Weire, and J. Pietruszewski
A nondestructive neutron activation technique for the simultaneous direct determination of chlorine, bromine, and iodine in
silver halide mixtures is described using a252Cf neutron multiplier (CFX). About 5–50 mg of sample are used. The analysis is semiroutine, without the need for a monitor
included with each sample since the flux stability and reproducibility are within ±1%, decaying only with the 2.65 year half-life
of252Cf. The precision and accuracy are counting-statistics controlled and are generally ±1% RSD or better. The method offers an
attractive alternative to existing chemical and instrumental methods for these determinations in silver halide mixtures because
it has the potential for providing reasonably rapid analyses with good precision and accuracy.
Authors:V. Volk, A. Karelin, A. Vakhrushin, and V. Karelin
The possibility of complex reprocessing of thermal off-steam and gas stream after its condensation is discussed. Two step pertraction process is proposed; in the first step the acids are extracted, and the metals in the second one. The principle flowsheet and material balance equations are given.
Two-phase additivity rule for radiation yields of p-nitrophenol, m-nitrophenol and p-nitrosophenol has been demonstrated. The data of partial radiation yields indicated that the nitrobenzene phase is by several times more reactive than a water phase /H2O, 3M HNO3 or 1.5M H2SO4/ in respect of nitrophenols formation.