Is bismuth subsalicylate an effective nontoxic catalyst for plga synthesis?

Poly(d,l ‐lactide‐co‐glycolide) (PLGA) copolyesters are commonly used in biomedical applications. Researches were carried out on nontoxic or low‐toxic catalysts that are enough efficient to provide short polymerization times, adequate microstructure chains and similar properties than the commercial PLGA materials. In this study, PLGA were synthesized by ring‐opening copolymerization (ROP) using three different catalysts. Stannous octoate is the first catalyst we used, as it is very efficient, even its toxicity is still on debate. Two others low‐toxic catalysts [zinc lactate and bismuth subsalicylate (BiSS)] were also evaluated. The comparison of these ROP was realized in terms of kinetics and control of the polymerization. Then, the influence of the catalyst on the PLGA microstructure chains is reported. Finally, abiotic hydrolytic degradation rate is studied. Results described in this article show that BiSS is one very attractive catalyst to produce low toxic PLGA for biomedical applications. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1130–1138     

Development of ion-conducting polymer electrolytes for use in high-energy lithium rechargeable batteries

Polymers based on poly(thylene oxide) (PEO) are a very promising new type of stable electrolytes for lithium rechargeable batteries. Their relatively low ionic conductivities can be more than compensated by the very small electrolyte thicknesses that can be used. Specific energies of 100 Wh/kg at sustained specific powers of 70 W/kg, have been obtained at Hydro-Québec with 100 μm of PEO electrolyte at 100°C. In an electric vehicle, this would give a driving range of over 300 km at 80 km/h, more than three times as much as lead-acid batteries. PEO-related polymers have been developed for lower temperature applications such as computers or portable appliances. Advantages over competitive Ni-Cd batteries are higher energy densities and absence of self-discharge, with expected shell lifes of 10 years. Laboratory prototypes (3600 cm², 10 Wh) demonstrate the absence of scale-up effects and excellent cycling capability (over 300 charge-discharge cycles).     

Nucleation and Growth Synthesis of Siloxane Gels to Form Functional,Monodisperse, and Acoustically Programmable Particles

Nucleation and growth methods offer scalable means of synthesizing colloidal particles with precisely specified size for applications in chemical research, industry, and medicine. These methods have been used to prepare a class of silicone gel particles that display a range of programmable properties and narrow size distributions. The acoustic contrast factor of these particles in water is estimated and can be tuned such that the particles undergo acoustophoresis to either the pressure nodes or antinodes of acoustic standing waves. These particles can be synthesized to display surface functional groups that can be covalently modified for a range of bioanalytical and acoustophoretic sorting applications.     

Flow field topology of transient mixing driven by buoyancy

Transient mixing driven by buoyancy occurs through the birth of a symmetric Rayleigh-Taylor morphology (RTM) structure for large length scales. Beyond its critical bifurcation the RTM structure exhibits self-similarity and occurs on smaller and smaller length scales. The dynamics of the RTM structure, its nonlinear growth and internal collision, show that its genesis occurs from an explosive bifurcation which leads to the overlap of resonance regions in phase space. This event shows the coexistence of regular and chaotic regions in phase space which is corroborated with the existence of horseshoe maps. A measure of local chaos given by the topological entropy indicates that as the system evolves there is growth of uncertainty. Breakdown of the dissipative RTM structure occurs during the transition from explosive to catastrophic bifurcation; this event gives rise to annihilation of the separatrices which drives overlap of resonance regions. The global bifurcation of explosive and catastrophic events in phase space for the large length scale of the RTM structure serves as a template for which mixing occurs on smaller and smaller length scales.     

为IBA C70回旋加速器设计研制的采用Cusp场型H-离子源与产生He束的ECR离子源的双束轴向注入系统

At the moment,a 70MeV cyclotron is under construction by the IBA company.This cyclotron will be able to accelerate H~- beam from a multicusp source and with a beam intensity in the range of 10mA at the source extraction.A He~(1 2 ) beam is also required.This beam will be produced by a PANTECHNIK ECR ion source(SUPERNANOGAN)with an extracted current of 1 to 2mA.In this paper the studies and design of the two sources with a common axial injection in the cyclotron are described.     

Sur la thermogravimétrie des précipités analytiques : Dosage du Potassium

The authors have studied the pyrolysis of 10 compounds of potassium and defined the limits of temperature between which they must dried in order to be determined accurately by weighing. Apart from the hexanitritocobaltate, the use of which is restricted to volumetric and coloimetric analysis, it can be said that the 9 other salts examined are well suited to the determination of potassium, the hydrontertrate, used within the limits prescribed by the authors, merits special attention.     

Sur la stabilité thermique des étalons analytiques. XIII

Résumé L'examen de 12 substances proposées comme étalons révèle que le chlorure et l'iodure de zinc doivent être manipulés à l'abri de l'humidité atmosphérique après séchage au-dessous de 60°; l'acétate et le sulfate de zinc issus d'un flacon neuf peuvent être pesés directement; le fluorure de sodium est parfaitement stable jusqu'à 850°; le carbonate de sodium et de potassium peut être utilisé tel quel mais il est préférable de le déshydrater entre 250 et 700°; l'hydrogénosulfate de potassium est hygroscopique et doit être séché avant pesée, sans dépasser 200°; l'hexaméthylènetétramine, le morpholine N-dithiocarbonate de morpholinium, le tétraphénylborure de sodium sont bien secs; il ne faut pas dépasser 150° pour obtenir la chloramine T anhydre. Les auteurs précisent la différence de comportement entre l'hydrogénosulfate et le pyrosulfate de potassium.

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Summary Study of 12 materials suggested as standards reveals that zinc chloride and iodide should be handled away from the atmospheric moisture after drying below 60°. Zinc acetate and sulfate freshly taken from a new bottle may be weighed immediately. Sodium fluoride is perfectly stable up to 850°. Sodium-potassium carbonate may be used just as they are but it is preferable to dry them between 250 and 700° before weighing. Potassium hydrogen sulfate is hygroscopic and should be dried prior to weighing but not above 200°. Hexamethylenetetramine, morpholinium morpholine-N-dithiocarbonate, sodium tetraphenyl boron are quite dry. Chloramine T can be obtained anhydrous without going higher than 150°. The difference in behavior between potassium hydrogen sulfate and pyrosulfate is stated precisely.

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Zusammenfassung Die Untersuchung 12 als Standard vorgeschlagener Substanzen ergab, daß Zinkchlorid und -jodid nach Trocknung unterhalb 60° zur Entfernung der Luftfeuchtigkeit verwendet werden können. Zinkacetat und -sulfat können nach Entnahme aus einer frischen Packung direkt eingewogen werden. Natriumfluorid ist bis 850° stabil. Natrium-Kaliumcarbonat kann wohl unmittelbar verwendet werden, doch ist es besser, es zwischen 250 und 700° zu entwässern. Kaliumhydrogensulfat ist hygroskopisch und muß vor dem Einwägen getrocknet werden, ohne die Temperatur über 200° zu steigern. Hexamethylentetramin, morpholin-N-dithiocarbonsaures Morpholinium und Natriumtetraphenylborat sind hinreichend trocken. Um wasserfreies Chloramin T zu erhalten, darf man nicht über 150° gehen. Der Unterschied im Verhalten von Kaliumhydrogensulfat und -pyrosulfat wird genau angegeben.

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Pour le 12ème mémoire de cette série, voir Mikrochim. Acta [Wien]1963, 348.

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En l'honneur du ProfesseurA. A. Benedetti-Pichler.