Chitosan gel film bandages: correlating structure, composition, and antimicrobial properties

Chitosan gel films were successfully obtained by evaporation cast from chitosan solutions in aqueous acidic solutions of organic acids (lactic and acetic acid) as gel film bandages, with a range of additives that directly influence film morphology and porosity. We show that the structure and composition of a wide range of 128 thin gel films, is correlated to the antimicrobial properties, their biocompatibility and resistance to biodegradation. Infrared spectroscopy and solid-state 13C nuclear magnetic resonance spectroscopy was used to correlate film molecular structure and composition to good antimicrobial properties against 10 of the most prevalent Gram positive and Gram negative bacteria. Chitosan gel films reduce the number of colonies after 24 h of incubation by factors of ∼105–107 CFU/mL, compared with controls. For each of these films, the structure and preparation condition has a direct relationship to antimicrobial activity and effectiveness. These gel film bandages also show excellent stability against biodegradation with lysozyme under physiological conditions (5% weight loss over a period of 1 month, 2% in the first week), allowing use during the entire healing process. These chitosan thin films and subsequent derivatives hold potential as low-cost, dissolvable bandages, or second skin, with antimicrobial properties that prohibit the most relevant intrahospital bacteria that infest burn injuries.

Investigation of the chemical origin and evidential value of differences in the SERS spectra of blue gel inks

Highly swellable polymer films doped with Ag nanoparticle aggregates (poly-SERS films) have been used to record very high signal:noise ratio, reproducible surface-enhanced (resonance) Raman (SER(R)S) spectra of in situ dried ink lines and their constituent dyes using both 633 and 785 nm excitation. These allowed the chemical origins of differences in the SERRS spectra of different inks to be determined. Initial investigation of pure samples of the 10 most common blue dyes showed that the dyes which had very similar chemical structures such as Patent Blue V and Patent Blue VF (which differ only by a single OH group) gave SERRS spectra in which the only indications that the dye structure had been changed were small differences in peak positions or relative intensities of the bands. SERRS studies of 13 gel pen inks were consistent with this observation. In some cases inks from different types of pens could be distinguished even though they were dominated by a single dye such as Victoria Blue B (Zebra Surari) or Victoria Blue BO (Pilot Acroball) because their predominant dye did not appear in other inks. Conversely, identical spectra were also recorded from different types of pens (Pilot G7, Zebra Z-grip) because they all had the same dominant Brilliant Blue G dye. Finally, some of the inks contained mixtures of dyes which could be separated by TLC and removed from the plate before being analysed with the same poly-SERS films. For example, the Pentel EnerGel ink pen was found to give TLC spots corresponding to Erioglaucine and Brilliant Blue G. Overall, this study has shown that the spectral differences between different inks which are based on chemically similar, but nonetheless distinct dyes, are extremely small, so very close matches between SERRS spectra are required for confident identification. Poly-SERS substrates can routinely provide the very stringent reproducibility and sensitivity levels required. This, coupled with the awareness of the reasons underlying the observed differences between similarly coloured inks allows a more confident assessment of the evidential value of inks SERS and should underpin adoption of this approach as a routine method for the forensic examination of inks.

SOL-GEL Lanthanum Phosphate, Composite and coating for functional Applications.

Lanthanum phosphate is one among the lanthanide family of “Rare Earths” following the periodic table of elements. Known under the generic name, Monazite, the rare earth phosphates have melting points above 1900 °C, high thermal phase stability, low thermal conductivity and thermal expansion coefficient similar to some of the high temperature oxides like alumina and zirconia.

Mise au point d'essais simples pour estimer les propriétés mécaniques et la sensibilité au gel des sols et des matériaux de chaussées

La conception de la structure d’une chaussée dépend en grande partie des caractéristiques du sol qui constituera l’infrastructure, telles que ses propriétés mécaniques réversibles et sa sensibilité à l’eau et au gel. Ces paramètres peuvent être mesurés en laboratoire grâce à l’exécution d’essais très fiables, mais laborieux et dispendieux comme par exemple les essais en cellule triaxiale et celui du potentiel de ségrégation en cellule de gel. L’utilisation des équipements portatifs, comme le déflectomètre LWD et le Percomètre®, permet d’effectuer une évaluation des propriétés du sol. Dix types de sols d’infrastructure ont été testés en laboratoire; les résultats ont été validés avec des essais in situ et corrélés avec les modules réversibles et les potentiels de ségrégation obtenus en laboratoire. Des modèles mathématiques ont été développés permettant une quantification adéquate du module réversible et du potentiel de ségrégation en fonction des propriétés géotechniques du sol.

Vysočajše utverždennyj ego imperatorskim" vělistvom" požarnyj ustav" dlâ g. Vyborga, izdannyj v" Gel'singforsě 26 ânvarâ 1840 goda

Julkaistu myös suomeksi nimellä: Palo-asetus Wiipurin kaupungille. - Julkaistu myös ruotsiksi nimellä: Brandordning för Wiborgs stad.