Development of a novel micro-assay for evaluation of peroxyl radical scavenger capacity: Application to carotenoids and structure-activity relationship

A micro-assay was developed and validated, using a microplate reader in 96-well format, C(11)-BODIPY(581/591) as fluorescent probe and AIBN as ROO() generator. The structure-activity relationship was established for 15 carotenoid standards, indicating that the opening of the β-ionone ring and the increase of chromophore extension in the carotenoid structure were the major factors leading to the increase of ROO() scavenging capacity. The values for ROO() scavenging capacity were calculated using α-tocopherol as reference compound. Among the studied carotenoids, all-trans-lycopene was the most efficient ROO() scavenger (8.67±0.74) followed by all-trans-astaxanthin (6.50±0.62). All the carotenoids showed to be more effective ROO() scavengers than α-tocopherol and some hydrophilic compounds. Finally, the method was successfully applied to assay the ROO() scavenging capacity of carotenoid extracts from two Amazonian fruits, peach palm (7.83±0.21) and mamey (6.90±0.44).     

In vivo and in vitro tracking of erosion in biodegradable materials using non-invasive fluorescence imaging

The design of erodible biomaterials relies on the ability to program the in vivo retention time, which necessitates real-time monitoring of erosion. However, in vivo performance cannot always be predicted by traditional determination of in vitro erosion, and standard methods sacrifice samples or animals, preventing sequential measures of the same specimen. We harnessed non-invasive fluorescence imaging to sequentially follow in vivo material-mass loss to model the degradation of materials hydrolytically (PEG:dextran hydrogel) and enzymatically (collagen). Hydrogel erosion rates in vivo and in vitro correlated, enabling the prediction of in vivo erosion of new material formulations from in vitro data. Collagen in vivo erosion was used to infer physiologic in vitro conditions that mimic erosive in vivo environments. This approach enables rapid in vitro screening of materials, and can be extended to simultaneously determine drug release and material erosion from a drug-eluting scaffold, or cell viability and material fate in tissue-engineering formulations.     

One Dimensional Inverse Dielectric Profiling of Embedded Slabs by a Quadratic Approximation

In this paper the inverse problem of the determination of the dielectric profile of a slab embedded into a homogeneous half space starting from the knowledge of the scattered field for different illumination angles is considered. A comparison between the features of a linear and a quadratic distorted approximation of the scattering problem is carried out, in order to determine the kind of profiles that can be reconstructed. In particular, the investigation of the direct problem reveals that, under the linear approximation, only a limited number of Fourier harmonics of the profile give contribution to the scattered field. The use of the quadratic approximation allows to change the number and order of the harmonic that can be imaged. The dependence of the results on the dielectric permittivity of the host medium is also highlighted. Numerical examples support the theoretical considerations.     

In Vivo Skin Permeation of Sodium Naproxen Formulated in Pluronic F-127 Gels: Effect of Azone® and Transcutol®

The objective of this study was to determine the penetration of sodium naproxen, formulated in Pluronic F-127 (PF-127) gels containing Azone® and Transcutol® as penetration enhancers, through human skin in vivo. It was found that the combination of Azone® and Transcutol® in PF-127 gels enhanced sodium naproxen penetration, with enhancement ratios of up to two fold compared with the formulation containing only Transcutol®. These results were confirmed by TEWL and ATR-FTIR spectroscopy, suggesting a synergic action for Azone® and Transcutol®. Because of the thermo-reversible behavior of Pluronic gels, the influence of the components added to the gel formulations on viscosity, as a function of temperature, was also studied.     

Microstructure and flow behaviour during backward extrusion of semi-solid 7075 aluminium alloy

The microstructure and flow behaviour during thixo backward extrusion of 7075 aluminium alloy were investigated. Reheating the steel die and the aluminium billet placed into the die at the same time using an induction furnace provides rapidly a very homogeneous microstructure suitable for thixoforming. During thixoextrusion, despite the high solid fraction, the solid globules are weakly connected and slide over each other without any plastic deformation. The flow remains quasi homogeneous resulting in homogeneous induced microstructure of the component.     

PUCK: an automated prompting system for smart environments: toward achieving automated prompting—challenges involved

The growth in popularity of smart environments has been quite steep in the last decade and so has the demand for smart health assistance systems. A smart home-based prompting system can enhance these technologies to deliver in-home interventions to users for timely reminders or brief instructions describing the way a task should be carried out for successful completion. This technology is in high demand given the desire of people who have physical or cognitive limitations to live independently in their homes. In this paper, with the introduction of the “PUCK” prompting system, we take an approach to automate prompting-based interventions without any predefined rule sets or user feedback. Unlike other approaches, we use simple off-the-shelf sensors and learn the timing for prompts based on real data that are collected with volunteer participants in our smart home test bed. The data mining approaches taken to solve this problem come with the challenge of an imbalanced class distribution that occurs naturally in the data. We propose a variant of an existing sampling technique, SMOTE, to deal with the class imbalance problem. To validate the approach, a comparative analysis with cost-sensitive learning is performed.     

Constitution, structural chemistry and magnetism in the ternary system Ce–Ag–Si

Phase relations were established for the Ce–Ag–Si system at 850°C by means of X-ray diffraction, light optical microscopy and quantitative electron probe microanalysis. Phase equilibria are characterised by the existence of extended solid solutions starting from the binaries: Ce(Ag_xSi_1−x)_2−y (ThSi₂-type), Ce(Ag_1−xSi_x)_1−y (unknown structure type) and Ce(Ag_1−xSi_x)_2−y (unknown structure type). Three ternary phases were found to exist, CeAg₂Si₂ (ThCr₂Si₂-type), Ce(Ag_xSi_1−x)_2−y (AlB₂-type) and the new ternary compound CeAgSi₂ with unknown structure type. Magnetic behaviour was studied from magnetic susceptibility and magnetisation measurements down to 1.7 K and employing magnetic fields up to 5 T. Soft ferromagnetism is observed for CeAg_xSi_2−x (AlB₂-type) below 5 K. Alloys Ce(Ag_xSi_1−x)_2−y with 0.08<x_Ag<0.30 (ThSi₂-type) encounter ferromagnetic order below 7 K. For x_Ag=0.31 the ferromagnetic interaction changes to antiferromagnetism with T_N=5.7 K. For CeAgSi₂ ferrimagnetic or canted antiferromagnetic order is indicated below 7 K.     

An apparatus for in situ spectroscopy of radiation damage of polymers by bombardment with high-energy heavy ions

A new target station providing Fourier transform infrared (FT-IR) spectroscopy and residual gas analysis (RGA) for in situ observation of ion-induced changes in polymers has been installed at the GSI Helmholtz Centre for Heavy Ion Research. The installations as well as first in situ measurements at room temperature are presented here. A foil of polyimide Kapton HN(?) was irradiated with 1.1 GeV Au ions. During irradiation several in situ FT-IR spectra were recorded. Simultaneously outgassing degradation products were detected with the RGA. In the IR spectra nearly all bands decrease due to the degradation of the molecular structure. In the region from 3000 to 2700 cm(-1) vibration bands of saturated hydrocarbons not reported in literature so far became visible. The outgassing experiments show a mixture of C(2)H(4), CO, and N(2) as the main outgassing components of polyimide. The ability to combine both analytical methods and the opportunity to measure a whole fluence series within a single experiment show the efficiency of the new setup.