PLGA, chitosan or chitosan-coated PLGA microparticles for alveolar delivery?. A comparative study of particle stability during nebulization

Various types of rifampicin (RIF)-loaded microparticles were compared for their stability during nebulization. Poly(lactide-co-glycolide) (PLGA), chitosan (CHT) and PLGA/CHT microparticles (MPs) were prepared by emulsion or precipitation techniques. MPs ability to be nebulized (NE%) as well as stability during freeze-drying or/and nebulization (NEED%), were evaluated after RIF extraction from MPs and determination by light spectroscopy. MP mean diameters and -potential values were measured by dynamic light scattering, morphology was assessed by SEM, cytotoxicity by MTT method and mucoadhesive properties by mucin association. In all cases, freeze-drying prior to nebulization did not affect EE%, NE or NEED%. In CHT, MPs RIF encapsulation efficiency (EE%) decreased with increasing CHT concentration (viscosity) and CHT-MP NEED% was higher when the polymer was crosslinked by glutaraldehyde. PLGA MPs, exhibited both higher RIF EE% and also higher nebulization ability and NEED%, compared to CHT ones, but also higher cytotoxicity. However, when the two polymers were combined in the PLGA/CHT MPs, EE%, NE% and NEED% increased with increasing MP CHT-content. PLGA/CHT MPs with 0.50% or 0.75% CHT exhibited highest EE% for RIF and also best nebulization ability and stability, compared to all other MP formulations studied. Additionally they had good mucoadhesive properties and comparably low cytotoxicity. © 2007 Elsevier B.V. All rights reserved

PtSe(2 )outperforms Pt as a counter electrode in dye sensitized solar cells

International audienceIn the present study, we show that PtSe2 films, prepared by soft selenization of pre-deposited Pt, is a very efficient counter electrode (CE) in dye sensitized solar cells (DSSCs). Devices based on PtSe2 achieve better photoconversion efficiency (9.5 and PLUSMN; 1.2%) than those employing bare Pt CE (9.18 and PLUSMN; 0.21%), even if the latter use three times more Pt loading than that used to prepare the PtSe2 CE. Films with of various Pt loadings have been prepared by electrodeposition and their catalytic properties have been investigated and compared with films of corresponding Pt loading which have been transformed to PtSe2 by low-temperature selenization. The improved performance of the PtSe2 CEs has been assigned to the higher availability of catalytic active sites and the more effective mechanism of interfacial electron transfer. This is a first attempt to explore the role of PtSe2 as the CE in DSSCs. The strong advantages of PtSe2 in relation to catalytic activity, stability, efficiency, combined with cost reduction, due to the lower mass loading required for a given performance, renders this noble-transition metal dichalcogenide a promising candidate to boost the performance of third generation photovoltaics, opening-up possibilities, at the same time, for other applications where Pt is used as the catalyst

Highly functional titania nanoparticles produced by flame spray pyrolysis : photoelectrochemical and solar cell applications

Nanoparticulate titania was synthesized by flame spray pyrolysis and was used to construct photoanodes for photoelectrochemical cells and quantum dot sensitized solar cells. Powders obtained by flame spray pyrolysis were composed of smaller nanoparticles and had higher specific surface areas than common commercial types of titania and this was carried over to the structure of the photoanodes and reflected on the photoelectrocatalytic and solar cell behavior of the photoanodes. The highest specific surface area and the smallest nanoparticle size produced in this work were 249 m2g-1 and 7 nm, respectively. CdS-sensitized photoanodes were affected by the amount of the deposited sensitizer, which was the largest in the case of the powder with the highest specific surface area. When, however, the photoanodes were loaded with a relatively large amount of CdSe sensitizer, the role of the latter increased and the differences between the different forms of titania diminished

Laser-assisted explosive synthesis and transfer of turbostratic graphene-related materials for energy conversion applications

International audienceProduction of high-grade graphene-like materials using a simple, reliable processes and its simultaneous transfer onto soft surfaces have not yet achieved; hence impeding wide-ranging graphene applications. Even more complex processes are required to prepare graphene-based nanohybrids, which offer additional synergistic functionalities in relation to graphene. Here, an uncomplicated and scalable process to prepare high-purity few-layer turbostratic graphene and graphene/SiOx nanohybrids is demonstrated employing laser-mediated explosive synthesis and transfer of graphene flakes. The process is capable of producing, and simultaneously transferring, graphene flakes on any substrate, such as polymer, glass, metal, ceramics, etc. Graphene and nanohybrids exhibit sp2 structures of turbostratic stacking, with low sheet resistance and very high (~30) C/O ratio. The merits of the method are showcased by two energy-related examples, flexible single-electrode triboelectric nanogenerators and electric double-layer capacitors. This method emerges as a paradigm of additive manufacturing for graphene-based devices with impact for applications in flexible electronics. © 2022, The Author(s)

Substrate related structural, electronic and electrochemical properties of evaporated CeOx ion storage layers

Summarization: Thin CeOx films were deposited on Indium Tin Oxide (ITO) coated glass and on Aluminium (Al) foil using electron beam evaporation. Combined analysis based on various experimental techniques has clearly revealed that the properties of the films are influenced by the substrate on which they are deposited: The CeOx/ITO films have smaller grain size and thus a larger amount of oxygen vacancies under reducing conditions than their CeOx/Al counterparts. Their morphology difference characterizes their behavior during lithiation: The CeOx/ITO films exhibit a Li+ diffusion coefficient of about one order of magnitude higher than that of the CeOx/Al films.Presented on: Thin Solid Film