Multiparametric Porous Silicon Sensors

We investigated the possibility of using several sensing parameters from porous silicon in order to improve gas selectivity. By fabricating porous silicon optical microcavities, three independent quantities can be measured, i.e. the electrical conductance, the photoluminescence intensity, and the wavelength of the optical resonance. We monitored the change of these three parameters as a function of NO2 (0.5-5 ppm), ethanol (300-15000 ppm) and relative humidity (0-100%). Preliminary results confirm that the examined species affect the parameters in a different way, both as a relative change and as dynamic

Spectroscopic characterisation of the naphthalene dioxygenase from Rhodococcus sp. StrainNCIMB12038

Polycyclic aromatic hydrocarbons (PAHs), such as naphthalene, are potential health risks due to their carcinogenic and mutagenic effects. Bacteria from the genus Rhodococcus are able to metabolise a wide variety of pollutants such as alkanes, aromatic compounds and halogenated hydrocarbons. A naphthalene dioxygenase from Rhodococcus sp. strain NCIMB12038 has been characterised for the first time, using electron paramagnetic resonance (EPR) spectroscopy and UV-Vis spectrophotometry. In the native state, the EPR spectrum of naphthalene 1,2-dioxygenase (NDO) is formed of the mononuclear high spin Fe(III) state contribution and the oxidised Rieske cluster is not visible as EPR-silent. In the presence of the reducing agent dithionite a signal derived from the reduction of the [2Fe-2S] unit is visible. The oxidation of the reduced NDO in the presence of O2-saturated naphthalene increased the intensity of the mononuclear contribution. A study of the “peroxide shunt”, an alternative mechanism for the oxidation of substrate in the presence of H2O2, showed catalysis via the oxidation of mononuclear centre while the Rieske-type cluster is not involved in the process. Therefore, the ability of these enzymes to degrade recalcitrant aromatic compounds makes them suitable for bioremediative applications and synthetic purposes

Dosimetry with gafchromic films based on a new micro-opto-electro-mechanical system

This work presents the first tests performed with radiochromic films and a new Micro‒Opto‒Electro-Mechanical system (MOEMS) for in situ dosimetry evaluation in radiotherapy in real time. We present a new device and methodology that overcomes the traditional limitation of time-delay in radiochromic film analysis by turning a passive detector into an active sensor. The proposed system consists mainly of an optical sensor based on light emitting diodes and photodetectors controlled by both customized electronic circuit and graphical user interface, which enables optical measurements directly. We show the first trials performed in a low‒energy proton cyclotron with this MOEMS by using gafchromic EBT3 films. Results show the feasibility of using this system for in situ dose evaluations. Further adaptation is ongoing to develop a full real‒time active detector by integrating MOEM multi‒arrays and films in flexible printed circuits. Hence, we point to improve the clinical application of radiochromic films with the aim to optimize radiotherapy treatment verifications

Quantification and improvement of the dynamics of human serum albumin and glycated human serum albumin with astaxanthin/astaxanthin-metal ion complexes: physico-chemical and computational approaches

Glycated human serum albumin (gHSA) undergoes conformational changes and unfolding events caused by free radicals. The glycation process results in a reduced ability of albumin to act as an endogenous scavenger and transporter protein in diabetes mellitus type 2 (T2DM) patients. Astaxanthin (ASX) in native form and complexed with metal ions (Cu2+ and Zn2+) has been shown to prevent gHSA from experiencing unfolding events. Furthermore, it improves protein stability of gHSA and human serum albumin (HSA) as it is shown through molecular dynamics studies. In this study, the ASX/ASX-metal ion complexes were reacted with both HSA/gHSA and analyzed with electronic paramagnetic resonance (EPR) spectroscopy, rheology and zeta sizer (particle size and zeta potential) analysis, circular dichroism (CD) spectroscopy and UV-Vis spectrophotometer measurements, as well as molecular electrostatic potential (MEP) and molecular docking calculations. The addition of metal ions to ASX improves its ability to act as an antioxidant and both ASX or ASX-metal ion complexes maintain HSA and gHSA stability while performing their functions

Global gene expression analysis of Canine cutaneous mast cell tumor: Could molecular profiling be useful for subtype classification and prognostication?

Prognosis and therapeutic management of dogs with cutaneous mast cell tumors (MCTs) depend on clinical stage and histological grade. However, the prognostic value of this latter is still questionable. In the present study, MCT transcriptome was analyzed to identify a set of candidate genes potentially useful for predicting the biological behavior of MCTs. Fifty-one canine MCT biopsies were analyzed. Isolated and purified total RNAs were individually hybridized to the Agilent Canine V2 4x44k DNA microarray. The comparison of reference differentiated and undifferentiated MCT transcriptome revealed a total of 597 differentially expressed genes (147 down-regulated and 450 up-regulated). The functional analysis of this set of genes provided evidence that they were mainly involved in cell cycle, DNA replication, p53 signaling pathway, nucleotide excision repair and pyrimidine metabolism. Class prediction analysis identified 13 transcripts providing the greatest accuracy of class prediction and divided samples into two categories (differentiated and undifferentiated), harboring a different prognosis. The Principal Component Analysis of all samples, made by using the selected 13 markers, confirmed MCT classification. The first three components accounted for 99.924% of the total variance. This molecular classification significantly correlated with survival time (p = 0.0026). Furthermore, among all marker genes, a significant association was found between mRNA expression and MCT-related mortality for FOXM1, GSN, FEN1 and KPNA2 (p<0.05). Finally, marker genes mRNA expression was evaluated in a cohort of 22 independent samples. Data obtained enabled to identify MCT cases with different prognosis. Overall, the molecular characterization of canine MCT transcriptome allowed the identification of a set of 13 transcripts that clearly separated differentiated from undifferentiated MCTs, thus predicting outcome regardless of the histological grade. These results may have clinical relevance and warrant future validation in a prospective study

Optical limiting sensor based on multilayer optimization of Ag/VO2 phase changing material

An optical limiting sensor working in the infrared was developed to address the need for eye and sensor protection against laser threats. Metallic and dielectric photonic resonators (thin-film multilayers) incorporating phase-change-materials (PCM) like VO2 were simulated and experimentally realized, with optimization of the deposition procedure by RF magnetron sputtering at low temperature. For the first time, the silver is placed between the substrate and the VO2 , thus improving the device limiting performances. By maximizing the difference of transmittance between the ‘ON’ and the ‘OFF’ states at the standard light wavelength for telecom applications (1550 nm), we calculated optimum thickness for VO2 and Ag films. The deposited thin films were characterized by SEM and Raman spectroscopy, and VO2 transition temperature was investigated by measuring resistance changes. As a proof of concept of the device working principle, we calculated transmittance drop of 70% when the sensor is exposed to a laser pulse excitation (20ps, 500 MW/cm^2 ). Our results pave the way for multilayer with optical limiting properties

Investigation of dopant profiles in nanosized materials by scanning transmission electron microscopy

Scanning electron microscopy is capable to provide chemical information on specimens interesting for the field of materials science and nanotechnology. The spatial resolution and the chemical information provided by incoherent imaging and detection of transmitted, forward-scattered electrons can reveal useful information about the specimen composition and microstructure. This paper discusses the capability and potential of low-voltage Scanning Transmission Electron Microscopy (STEM) for the characterization of multilayered structures and dopant profiles in crystalline materials