Purification of biomimetic apatite-based hybrid colloids intended for biomedical applications: a dialysis study

The field of nanobiotechnology has lately attracted much attention both from therapeutic and diagnosis viewpoints. Of particular relevance is the development of colloidal formulations of biocompatible nanoparticles capable of interacting with selected cells or tissues. In this context, the purification of such nanoparticle suspensions appears as a critical step as residues of unreacted species may jeopardize biological and medical outcomes, and sample purity is thus increasingly taken into account by regulatory committees. In the present work, we have investigated from a physico-chemical point of view the purification by dialysis of recently developed hybrid colloids based on biomimetic nanocrystalline apatites intended for interacting with cells. Both Eu-doped (2 mol.% relative to Ca) and Eu-free suspensions were studied. The follow-up of the dialysis process was carried out by way of FTIR, TEM, XRD, pH and conductivity measurements. Mathematical modelling of conductivity data was reported. The effects of a change in temperature (25 and 45 ◦C), dialysis medium, and starting colloid composition were evaluated and discussed. We show that the dialysis method is a well-adapted and cheap technique to purify such mineral–organic hybrid suspensions in view of biomedical applications, and we point out some of the characterization techniques that may prove helpful for following the evolution of the purification process with time

Exploiting textual source information for epidemiosurveillance

In recent years as a complement to the traditional surveillance reporting systems there is a great interest in developing methodologies for early detection of potential health threats from unstructured text present on the Internet. In this context, we examined the relevance of the combination of expert knowledge and automatic term extraction in the creation of appropriate Internet search queries for the acquisition of disease outbreak news. We propose a measure that is the number of relevant disease outbreak news detected in function of the terms automatically extracted from a set of example Google and PubMED corpora. Due to the recent emergence we have used the African swine fever as a disease example. (Résumé d'auteur

Lambiotte, Premery, France: An industrial pyrolysis biorefinery operated during 120 years

The Lambiotte process is a well-known process for the continuous carbonization of wood. It is also sometimes called as the “CISR” process which is still in operation in Belgium, France, etc. [1, 2]. But this process is the small and simplified “son” of a much more advanced process (sometimes called as “SIFIC”) developed by the Lambiotte company in France (in Premery). The CISR reactor is smaller than the SIFIC one and burns the condensable products to produce mainly char. The SIFIC process was an integrated forest-refinery. It was operated in Premery to produce about 20000 tons per year of char from about 100000-120000 tons of wet wood (~45% moisture content, before drying in mobile vertical beds) but also to produce various chemicals from the carbonization bio-oils. The carbonization oil was fractionated and purified in an advanced process combining solvent extraction, distillation (more than 40 distillation columns) and catalytic reactions. In the beginning of the 20th century, the factory was able to produce: methanol, formol and their derivatives, acetates and solvent (from acetic acid), creosote, guaiacol, (wood) pitch, various medicines (such as antiseptics). Then even food aromas have been produced. Please click Additional Files below to see the full abstract

Synthesis and Optical Properties of Cu2CoSnS4 Colloidal Quantum Dots

Monodisperse quaternary chalcopyrite Cu2CoSnS4 colloidal quantum dots have been synthesized by acid peptization of a tailored Cu2CoSnS4 precursor displaying loosely packed, ultrafine primary crystallites. Well-defined peaks shifted to higher energy compared to the Cu2CoSnS4 bulk band gap value were observed on the UV-Vis absorption curve consistent with a quantum confinement behavior. First investigations by room temperature time resolved photoluminescence (TRPL) spectroscopy suggest that the photoluminescence emission does not arise from a donor–acceptor recombination.

Bacterioplankton production determined by DNA synthesis, protein synthesis, and frequency of dividing cells in Tuamotu atoll lagoons and surrounding ocean

This study compares three independent methods used for estimating bacterioplankton production in waters from the lagoon (mesotrophic) and the surrounding ocean (oligotrophic) of two atolls from the Tuamotu archipelago (French Polynesia). Thymidine and leucine incorporation were calibrated in dilution cultures and gave consistent results when the first was calibrated against cell multiplication and the second against protein synthesis. This study demonstrates that determining conversion factors strongly depends on the selected calculation method (modified derivative, integrative, and cumulative). These different estimates are reconciled when the very low proportion of active cells is accounted for. Frequency of dividing-divided cells (FDDC) calibrated using the same dilution cultures led to unrealistically high estimates of bacterial production. However, highly significant correlations between FDDC and either thymidine- or leucine-specific incorporation per cell were found in lagoon waters in situ. These correlations became more positive when oceanic data were added. This suggests that the FDDC method is also potentially valid to determine bacterioplankton growth rates after cross calibration with thymidine or leucine methods. If recommended precautions are observed, the three methods tested in the present study would give reliable production estimates. (Résumé d'auteur

Employee Responses To Psychological Contract Breach And Violation: Intentions To Leave The Job, Employer Or Profession

Empirical research supports the idea that the perception of under-fulfillment of psychological contract (i.e., breach and violation) increases the willingness to leave the employer via turnover cognitions (i.e., available alternatives and search a job). Further research indicates that employee turnover is not only restricted to the notion of an employee leaving an employer to join another employer. To go beyond this restriction, data were collected among a sample of professional employees. The results suggest that when employees feel that under-fulfillment of psychological contract occur, they may leave the organization or the current job for one another by in the same organization, but did not consider leaving the profession. Findings are discussed in light of relevant literature

DIGISAFE® XME: High Availability Vital Computer

International audienceDuring the 1980s, progress achieved in automation systems led us to computerize functions that had hitherto used hard wired or relay logic. This especially included system safety related functions which previously used hardware based systems. The safety of these functions was based on a "failsafe" principle: any failure placed the equipment in a non dangerous state

Microscopie à deux photons pour l’imagerie cellulaire fonctionnelle : avantages et enjeux. ou Un photon c’est bien… mais deux c’est mieux !

L’observation de la dynamique des événements moléculaires dans la cellule in situ présente une série de défis, notamment la capacité de suivre ces événements avec le maximum de résolution spatiale et temporelle tout en minimisant l’interférence avec la biologie du tissu et de la cellule. L’exploitation récente d’approches fondées sur l’optique non-linéaire, telle que la microscopie par balayage laser de fluorescence produite par excitation à deux photons, a permis de faire des progrès énormes dans ce domaine, notamment parce qu’elle permet de faire des mesures dans un espace très confiné à l’intérieur du tissu intact et à des profondeurs inaccessibles avec la microscopie linéaire conventionnelle. En minimisant l’excitation indésirable du tissu en dehors du point focal, on améliore la résolution et la sensibilité, on simplifie le système optique et on minimise la phototoxicité. Ces avantages sont à la source du succès de la microscopie à deux photons pour l’imagerie cellulaire fonctionnelle. Des percées récentes en optique/photonique permettent d’envisager d’améliorer davantage la résolution spatiale et temporelle de ce type d’imagerie et la capacité de sonder encore plus profondément dans le tissu pour repousser les limites de la biochimie fonctionnelle et de la biologie cellulaire actuelles.One of the main challenges of modern biochemistry and cell biology is to be able to observe molecular dynamics in their functional context, i.e. in live cells in situ. Thus, being able to track ongoing molecular events with maximal spatial and temporal resolution (within subcellular compartments), while minimizing interference with tissue biology, is key to future developments for in situ imaging. The recent use of non-linear optics approaches in tissue microscopy, made possible in large part by the availability of femtosecond pulse lasers, has allowed major advances on this front that would not have been possible with conventional linear microscopy techniques. Of these approaches, the one that has generated most advances to date is two-photon laser scanning fluorescence microscopy. While this approach does not really provide improved resolution over linear microscopy in non absorbing media, it allows us to exploit a window of low absorbance in live tissue in the near infrared range. The end result is much improved tissue penetration, minimizing unwanted excitation outside the focal area, which yields an effective improvement in resolution and sensitivity. The optical system is also simplified and, more importantly, phototoxicity is reduced. These advantages are at the source of the success of two-photon microscopy for functional cellular imaging in situ. Yet, we still face further challenges, reaching the limits of resolution that conventional optics can offer. Here we review some recent advances in optics/photonics approaches that hold promises to improve our ability to probe the tissue in finer areas, at faster speed, and deeper into the tissue. These include super-resolution techniques, introduction of non paraxial optics in microscopy and use of amplified femtosecond lasers, yielding enhanced spatial and temporal resolution as well as tissue penetration