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The toxic oxyanion tellurite (TeO32-) is acquired by cells of Rhodobacter capsulatus grown anaerobically in the light, via acetate permease ActP2 and then reduced to Te-0 in the cytoplasm as needle-like black precipitates. Interestingly, photosynthetic cultures of R. capsulatus can also generate Te-0 nanoprecipitates (TeNPs) outside the cells upon addition of the redox mediator lawsone (2-hydroxy-1,4-naphtoquinone). TeNPs generation kinetics were monitored to define the optimal conditions to produce TeNPs as a function of various carbon sources and lawsone concentration. We report that growing cultures over a 10 days period with daily additions of 1 mM tellurite led to the accumulation in the growth medium of TeNPs with dimensions from 200 up to 600-700 nm in length as determined by atomic force microscopy (AFM). This result suggests that nucleation of TeNPs takes place over the entire cell growth period although the addition of new tellurium Te-0 to pre-formed TeNPs is the main strategy used by R. capsulatus to generate TeNPs outside the cells. Finally, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) analysis of TeNPs indicate they are coated with an organic material which keeps the particles in solution in aqueous solvents. (C) 2016 Published by Elsevier B.V.

Palmitoylethanolamide (PEA) belongs to a group of endogenous molecules known as acylethanolamides. PEA has a great pharmacological potential based on its anti-inflammatory and analgesic properties, although its use is somewhat limited by the high lipophilic nature of the molecule, thereby impairing its use, particularly by topical and injective routes. Here we report the synthesis, pharmacodynamic and pharmacokinetic characterization of a series of Polyethylene glycol conjugates (esters and carbonates) of PEA and its analogous acylethanolamides, that have improved chemical and physical properties, i.e., higher water solubility and good hydrophilic/lipophilic balance, resulting in (i) improved accumulation in tissues (particularly skin and mucosae), (ii) prolonged release, and (iii) increased bioavailability. In particular, here we report the improvement of PEA and analogous acylethanolamides levels in the tissues - particularly in the skin and mucosae - and their prolonged release due to the improved bioavailability of related conjugates. Pharmacological properties of polyethylene glycol conjugates of PEA have been tested in experimental models of inflammation and inflammation-sustained pain (carrageenan induced oedema and mechanical hyperalgesia), two models in which PEA and analogous acylethanolamides activity has been widely described. Our results demonstrate that conjugates are able to extend the time frame in which PEA and analogous acylethanolamides exert their pharmacological effects. These results clearly indicate that polyethylene glycol conjugates of PEA and analogous acylethanolamides could provide powerful pharmacological tools when a prolonged anti-inflammatory and analgesic action of such molecules is desired.

The loss in performance during fuel cell operation is one of the critical factors that hamper fuel cells commercialization. This paper presents the University of Trieste Engineering and Architecture department research activity related to High Temperature Polymer Electrode Membrane (HT-PEM) fuel cell degradation. The aim of the research is to correlate catalyst degradation with fuel cell operation mode and performance. For evaluating catalyst degradation, a procedure to analyze the Membrane Electrode Assembly (MEA) with Small Angle X-ray Scattering (SAXS) technique has been developed and presented. Furthermore, accelerated degradation test have been carried out for samples conditioning. Preliminary SAXS analysis results confirm the agglomeration of the Pt particles that leads to a growth in size from 5 nm up to 8 nm for the considered MEAs. Accelerated degradation tests show a fuel cell loss in performance lower than 6% after 100,000 load cycling. First SAXS results of these tests are presented.

Realizzare un sistema di acquisizione dati e controllo che permetta di valutare la vita operativa di celle a combustibile polimeriche mediante test di degrado accelerato. Il sistema si deve caratterizzare per la facilità di utilizzo, la possibilità di attuare automaticamente differenti protocolli di test ed essere in grado di comunicare in remoto qualsiasi tipo di problematica. Inoltre deve essere garantita la riproducibilità e conformità delle prove effettuate.

2013/2014 Durability and cost are the major limiting factors in current PEM fuel cells development and commercialization. Electrocatalyst materials are the main responsible of both cost of the entire fuel cell stack and its degradation during operation [1,2]. In this research durability and degradation have been investigated in high temperature PEM fuel cells (HT-PEMFCs). Specific diagnostic techniques have been studied and tested for the investigation of electrocatalyst structural properties. An experimental sensibility analysis has been carried out with the purpose to assess advantages and limitations of the use of cyclic voltammetry to determine the electrocatalyst ECSA in H3PO4/PBI high temperature PEM fuel cells. Small angle x-ray scattering (SAXS) has been used to obtain structural information of the electrocatalyst nanoparticles, such as size and distribution. A procedure to characterize HT-PEMFCs MEAs by means of SAXS has been developed and tested. Transmission electron microscopy (TEM) is a complementary technique to SAXS: it has been used to validate the diagnostic method and to compare the results. Electrocatalyst evolution during long-term operation has been studied and related with performance loss. Specific stress test protocols have been developed to accelerate electrocatalyst degradation in commercial HT-PEMFC MEAs operated in single cell configuration. Two MEAs have been subjected to load cycling and one to start/stop cycling. One of the two testing protocols based on load cycling included open circuit (OC) condition in each cycle with the purpose to study the effects of frequent and short OCs during operation on MEA durability and electrocatalyst evolution. Specific start-up and shutdown procedures have been used in the start/stop test in order to limit other degradation mechanisms. Cell voltage and polarization curves have been recorded to monitor cell performance during the durability tests. The electrocatalyst structural evolution induced by load cycling has been characterized with SAXS and TEM. The stress test protocols have been effective to accelerate performance and electrocatalyst degradation of the MEA. The voltage decay rate at 200 mAcm-2 was higher than 25 μVh-1 in the samples subjected to load cycles. The start/stop cycling caused a performance degradation of 18 μV/cycle at 222 mAcm-2 during the first 450 cycles of the test. Regarding the diagnostic techniques used to characterize the electrocatalyst, cyclic voltammetry (CV) seems not to be particularly reliable when performed at high temperatures (>100°C) due to the high dependence of the voltammogram shape to humidity conditions. SAXS, on the other hand, seems to be an effective tool to investigate structural properties of PEMFC electrocatalysts. SAXS analysis showed that after 100,000 load cycles the mean size of the platinum nanoparticles more than doubled. TEM results varied about 30% from the SAXS results: this divergence could be due to a very different population size of the nanoparticles that have been analysed in the two methods. Moreover, the preparation of the sample used in TEM may have strongly influenced the electrocatalyst structure. Finally, a visualization of the electrocatalyst structural evolution on large areas of the MEAs subjected to load cycling showed preferential directions of the particles growth that could be due to the position of the channels on the flow-field plates of the fuel cell. XXVII Ciclo 1987

The catalyst layer is one of the most critical components of a PEM fuel cell. The catalyst, in the form of platinum nanoparticles, tends to aggregate and sinter during operation, with the consequence to reduce its active area thus the efficiency of the entire fuel cell. This paper aims to highlight the efficiency of scanning electron microscopy (SEM) and synchrotron small-angle X-ray scattering (SAXS) to characterize the catalyst layer degradation of a commercial MEA for high temperature PEM fuel cells. SEM is an effective tool for the surface analysis of the samples, since it is able to obtain a magnification from 10x up to 105x. SAXS is a suitable technique to investigate the structural features of colloidal scale (between 10 and 103 Å). The paper presents in detail the analysis of three MEAs: one is a virgin sample, one was operated discontinuously in a single fuel cell, one operated in a 25 cells stack. The experiments show the degradation of the catalyst layer after operation. In particular, the agglomeration of the Pt particles leads to a growth in size from 5 nm up to 8 nm.

The design of beta-cyclodextrin/multiwalled carbon nanotubes hybrid (beta-CD-MWCNT) as nanoplatform for the entrapment and delivery of guanine based drugs is described here. The functionalized carbon nanomaterials have been characterized by XPS spectroscopy, electron microscopy (FEG-SEM and TEM), AFM, TGA, and FT-IR to achieve insights on structure, morphology and chemical composition. The drug binding abilities of nanocarrier towards the guanine (G) and Acyclovir (Acy) were proved by UV-vis and DSC experiments. Host-guest equilibrium association constants and drug loading have been evaluated for G/beta-CD-MWCNT and Acy/beta-CD-MWCNT complexes. The release studies showed a sustained delivery of Acy without initial burst effect confirming a strong interaction of drug with the nanoplatform sites. The preliminary antiviral data indicated that the Acyclovir loaded into the beta-CD-MWCNT platform interferes with HSV-1 replication and the antireplicative effect was higher than the free drug. (C) 2014 Elsevier B.V. All rights reserved.