Structure influence on biophenols solubility in model biomembranes detected by differential scanning calorimetry

The protective effects of some foods, in particular fruits and vegetables, against cardiovascular disease and cancer are believed to be due to the presence of antioxidant substances such as hydroxyaromatic compounds. The aim of this work was to study (i) the interaction of three biophenols derived from benzoic acid (p-hydroxybenzoic acid, vanillic acid, syringic acid and benzoic acid) with model biomembranes and (ii) their transfer through an aqueous medium to be absorbed into a lipid bilayer, investigating the effect they exert on the thermotropic behaviour of model membranes represented by dimyristoylphosphatidylcholine multilamellar vesicles using differential scanning calorimetry. The compounds, when dispersed in liposomes during their preparation, at pH = 4, were found to modify the gel to liquid crystal phase transition of the lipid vesicles, causing a temperature shift towards lower values. The temperature shift was a function of the concentration of acids in the lipid aqueous dispersions and their lipophilic character. The kinetic experiments of compounds transfer through the aqueous medium and the absorption by the bilayer were performed contacting the antioxidant compounds (at a fixed concentration) and the model membrane at increasing incubation times. These experiments reveal that the transfer of the examined compounds through the aqueous medium and their uptake by bilayer are influenced by the presence of substituents located on the ring, which should consequently modify their lipophilicity.     

Calorimetric approach of the interaction and absorption of polycyclic aromatic hydrocarbons with model membranes

The ability of polycyclic aromatic hydrocarbons (PAHs) to interact with cell membranes outer lipid layer and subsequently to penetrate inside cells can be a prerequisite for exhibiting a mutagenic and carcinogenic activity. The effect exerted by pyrene, benzo[a]pyrene, and anthracene, three structurally similar polycyclic aromatic hydrocarbons possessing mutagenic and carcinogenic activity on the thermotropic behavior of model membranes represented by dimyristoylphosphatidylcholine (DMPC) vesicles, was investigated by differential scanning calorimetry (DSC). The examined compounds, when dispersed in liposomes during their preparation, exerted a different action on the gel-to-liquid crystal phase transition of DMPC multilamellar vesicles. Pyrene and benzo[a]pyrene affected the transition temperature (Tm), shifting it toward lower values with a concomitant decrease of the associated enthalpy changes (AM). Anthracene does not significantly affect the thermotropic behavior of lipid vesicles for all tested concentrations. The interaction between PAHs and model membranes was also studied by considering the ability of such compounds as a finely powdered solid or adsorbed on soil surrogate (constituted by silica gel) to migrate through an aqueous medium. This transfer process was compared with the PAHs intermembrane transfer from PAH loaded liposomes to empty membranes. These processes can mimic absorption kinetics mediated by hydrophilic or lipophilic media. No interaction occurred between model membranes and solid PAHs. A very small effect was also observed for PAHs released by silica gel, suggesting that the migration and absorption are hindered by the aqueous layer and that their low hydrophilic character inhibits migration through the aqueous layer surrounding the multilamellar vesicles (MLV). Different behavior was observed by considering the time-dependent studies carried out by contacting, for increasing times, equivalent amounts of empty DMPC vesicles with PAH loaded ones; all compounds were able to migrate between the two different kinds of model membranes. Thus, PAHs are unable to reach and penetrate biological membranes migrating through an aqueous layer but, when dispersed in a lipophilic medium, are able to penetrate and diffuse inside a membrane. The obtained experimental results seem to validate the employment of the DSC technique in order to study the ability of bioactive compounds, not only to interact with biological membranes, but also to be adsorbed inside a cell when dispersed in a lipophilic medium.     

Validation of a confirmatory analytical method for the determination of aflatoxins B1, B2, G1 and G2 in foods and feed materials by HPLC with on-line photochemical derivatization and fluorescence detection

A sensitive and selective analytical method for the simultaneous separation and quantitative determination of aflatoxins B₁, B₂, G₁ and G₂ in foodstuffs and materials for feed has been validated. The method is based on high performance liquid chromatography with on-line post-column photochemical derivatization and fluorescence detection. The chromatographic separation of aflatoxins was accomplished using a C₁₈ column eluted with an isocratic mobile phase consisting of water, methanol and acetonitrile. The sample preparation required a simple extraction of aflatoxins with MeOH/H₂O (80:20, v/v) and a purification step by immunoaffinity column cleanup. The total analysis time, including sample preparation and chromatographic separation, did not exceed 40 min with a run time of 10 min. The on-line photochemical derivatization ensures better results in terms of simplicity, sensitivity and reproducibility with respect to chemical derivatization techniques, and provides an increase of the peak resolution and an extent of automation in comparison with the electrochemical ones. The procedure for the determination of aflatoxins in food samples and cereals for animal consumption was extensively validated following Regulation (EC) No. 882/2004. Detection limits in wheat bran samples of 0.08 µg kg^?1 for AFB₁, 0.02 µg kg^?1 for AFB₂, 0.16 µg kg^?1 for AFG₁ and 0.04 µg kg^?1 for AFG₂ were attained. The method allows high recovery with mean values ranging from 72 to 94% and it satisfies the necessary requirements for sensitivity, linearity, selectivity, precision and ruggedness, demonstrating the conformity of the method with provisions of Regulation (EC) No. 401/2006.     

Pulsed Electromagnetic Fields in Bone Healing: Molecular Pathways and Clinical Applications

In this article, we provide an extensive review of the recent literature of the signaling pathways modulated by Pulsed Electromagnetic Fields (PEMFs) and PEMFs clinical application. A review of the literature was performed on two medical electronic databases (PubMed and Embase) from 3 to 5 March 2021. Three authors performed the evaluation of the studies and the data extraction. All studies for this review were selected following these inclusion criteria: studies written in English, studies available in full text and studies published in peer-reviewed journal. Molecular biology, identifying cell membrane receptors and pathways involved in bone healing, and studying PEMFs target of action are giving a solid basis for clinical applications of PEMFs. However, further biology studies and clinical trials with clear and standardized parameters (intensity, frequency, dose, duration, type of coil) are required to clarify the precise dose-response relationship and to understand the real applications in clinical practice of PEMFs.     

Recent progress in Bose-Einstein condensation experiments

When the atoms in a gas are cooled to extremely low temperatures, their quantum-mechanical nature starts to dominate the properties of the whole gas. Under the appropriate conditions, the atoms will 'condense' into a single quantum state of the system-a phenomenon known as Bose-Einstein condensation (BEC). The resulting 'condensate' behaves as a single, observable quantum-mechanical object. During the last decade, this new state of matter has displayed many remarkable properties. In this paper, we review some of the most recent experimental developments in the BEC field, highlighting the role of atomic interactions and the high degree of control with which condensates may be manipulated.     

Estimation of the cortical connectivity by high-resolution EEG and structural equation modeling: simulations and application to finger tapping data

Today, the concept of brain connectivity plays a central role in the neuroscience. While functional connectivity is defined as the temporal coherence between the activities of different brain areas, the effective connectivity is defined as the simplest brain circuit that would produce the same temporal relationship as observed experimentally between cortical sites. The most used method to estimate effective connectivity in neuroscience is the structural equation modeling (SEM), typically used on data related to the brain hemodynamic behavior. However, the use of hemodynamic measures limits the temporal resolution on which the brain process can be followed. The present research proposes the use of the SEM approach on the cortical waveforms estimated from the high-resolution EEG data, which exhibits a good spatial resolution and a higher temporal resolution than hemodynamic measures. We performed a simulation study, in which different main factors were systematically manipulated in the generation of test signals, and the errors in the estimated connectivity were evaluated by the analysis of variance (ANOVA). Such factors were the signal-to-noise ratio and the duration of the simulated cortical activity. Since SEM technique is based on the use of a model formulated on the basis of anatomical and physiological constraints, different experimental conditions were analyzed, in order to evaluate the effect of errors made in the a priori model formulation on its performances. The feasibility of the proposed approach has been shown in a human study using high-resolution EEG recordings related to finger tapping movements.     

Discriminating real objects in radar imaging by exploiting the squared modulus of the continuous wavelet transform

New technique based on continuous wavelet transform (CWT) for classifying objects in synthetic aperture radar (SAR) imaging is presented. The CWT allows to analyse two-dimensional SAR images to highlight the frequency and angular behaviour of the scatterers. This technique allows to build a SAR hyperimage, that is, a four-dimensional data cube which represents for each spatial location (x, y) of the scatterer in the image, its frequency and angular energy behaviour. When analysing different targets, objects or areas in SAR images, it has been recently observed that some scatterers belonging to a same class of objects could have similar frequency and angular energy responses. The previous observations have motivated the determination to exploit these energy responses to discriminate these objects. This discrimination is performed by frequency and angular correlations between the response of a particular scatterer (measured) and those of all the scatterers in the SAR image. Some examples of discrimination from real SAR data are presented and show an interest of the method for target classification and recognition for SAR imaging     

Bioinspired Metal-Organic Frameworks in Mixed Matrix Membranes for Efficient Static/Dynamic Removal of Mercury from Water

The mercury removal efficiency of a novel metal-organic framework (MOF) derived from the amino acid S-methyl-L-cysteine is presented and the process is characterized by single-crystal X-ray crystallography. A feasibility study is further presented on the performance of this MOF—and also that of another MOF derived from the amino acid L-methionine—when used as the sorbent in mixed matrix membranes (MMMs). These MOF-based MMMs exhibit high efficiency and selectivity—in both static and dynamic regimes—in the removal of Hg²⁺ from aqueous environments, due to the high density of thioalkyl groups decorating MOF channels. Both MMMs are capable to reduce different concentration of the pollutant to acceptable limits for drinking water (<2 parts per billion). In addition, a novel device, consisting of the recirculation and adsorption of contaminated solutions through the MOF–MMMs, is designed and successfully explored in the selective capture of Hg²⁺. Thus, filtration of Hg²⁺ solutions with multiple passes through the permeation cell shows a gradual decrease of the pollutant concentration. These results suggest that MOF-based MMMs can be implemented in water remediation, helping to reduce either contaminants from accidental unauthorized or deliberate metal industrial dumping and to ensure access for clean and potable freshwater.     

SPIRE: a digital library for scientific information

In this paper we describe the architecture and implementation of a digital library framework for scientific data, particularly imagery, with a focus on support for content-based search. Content is specified by the user at one or more of the following abstraction levels: pixel, feature, and semantic. An object-definition mechanism has been developed that supports example-based and constraint-based specification of both simple and complex query targets.This framework incorporates a methodology yielding a computationally efficient implementation of image processing algorithms, thus allowing the interactive, real-time extraction and manipulation of user-specified features and content during the execution of queries. The framework is well-suited for searching scientific databases, including satellite imagery, and medical and seismic data repositories, where the richness of the information does not allow the a priori generation of exhaustive indexes.