Salmonella biofilms: An overview on occurrence,structure, regulation and eradication

The ability of Salmonella to form complex surface-associated communities, called biofilms, contributes to its resistance and persistence in both host and non-host environments and is especially important in food processing environments. In this review, the different types of abiotic (plastic, glass, cement, rubber, and stainless steel) and biotic surfaces (plant surfaces, epithelial cells, and gallstones) on which Salmonella biofilms have been described are discussed, as well as a number of commonly used laboratory setups to study Salmonella biofilm formation (rdar morphotype, pellicle formation, and biofilms on polystyrene pegs). Furthermore, the structural components important during Salmonella biofilm formation are described (curli and other fimbriae, BapA, flagella, cellulose, colanic acid, anionic O-antigen capsule and fatty acids), with special attention to the structural variations of biofilms grown on different surfaces and under different conditions. Indeed, biofilm formation is strongly influenced by different environmental signals, via a complex regulatory network. An extensive overview is given on the current understanding of this genetic network and the interactions between its different components (CsgD, RpoS, Crl, OmpR, IHF, H-NS, CpxR, MlrA, c-di-GMP, BarA/SirA, Csr, PhoPQ, RstA, Rcs, metabolic processes and quorum sensing). To further illustrate that biofilm formation is a mechanism of Salmonella to adapt to different environments, the resistance of Salmonella biofilms against different stress factors including desiccation stress, disinfectants (e.g. hypochlorite, glutaraldehyde, cationic tensides and triclosan) and antibiotics (e.g. ciprofloxacin) is described. Finally, a number of Salmonella biofilm inhibitors, identified through bottom-up- and top-down-approaches, are discussed, such as surfactin, glucose, halogenated furanones, 4(5)-aryl 2-aminoimidazoles, furocoumarins and salicylates. Also the potential of combination therapy (e.g. combinations of triclosan and quaternary ammonium salts or halogenated furanones and antibiotics/disinfectants) and nano- and micro-emulsions to inhibit Salmonella biofilm formation is discussed. Insight into the pathogen's complex biofilm process will eventually lead to further unraveling of its intricacies and more efficient strategies to combat Salmonella biofilms.     

Antioxidant activity of phenolic and phenylethanoid glycosides from Teucrium polium L

In the present study, the chemical composition and antioxidant activities of Teucrium polium L. (Lamiaceae) were assessed. Fractionation of methanol extract obtained from the aerial parts of T. polium yielded one new phenylethanoid glycoside, named poliumoside B, together with four known flavonoids, two iridoid glycosides and a known poliumoside. The structures of all of these compounds were elucidated on the basis of spectroscopic data from 1D and 2D NMR experiments and MS spectral analyses. The antioxidant activities of the crude extracts and of the isolated compounds were evaluated through tests such as DPPH radical-scavenging capability, reducing power, xanthine oxidase inhibitory effect and inhibition of linoleic acid peroxidation. The highest antioxidant activity was found in the n-butanol extract, which also contained active polyphenols, thus suggesting that this plant could be used as a source of natural molecules, to provide safe antioxidant additives and nutraceuticals. The structure–activity relationships of the isolated compounds are also discussed.     

A new test cell for the evaluation of thermo-physical performance of facades building components

How do the new building façade components work under real climatic conditions? The question is especially related to the dynamic behaviour of new and complex components such as the ventilated walls, the Phase Change Material, or others that use nano-technologies and aerogels. One of the objectives of the undergoing research activity, named Abitare Mediterraneo, is the evaluation of their thermal behaviour through the use of an outdoor test cell, in order to reproduce under the real external conditions the performance of these components, and consequently define the main thermal parameters such as the attenuation factor and the thermal inertia, characterising the component; moreover, the results will be used to write new algorithms for dynamic simulation tools allowing an appropriate evaluation of the complex behaviour of the whole building at a real scale condition. The new test cell is realised in Florence, Italy. The design starts from the study of the experience of the existing PASSYS test cells, overtaking the main weakness of the building structure and of the heat-flux sensors.     

Optical and electrical characterization of carbon nanoparticles produced in laminar premixed flames

Optical and electrical properties of carbonaceous particles produced in laboratory scale, premixed ethylene/air flames are obtained. Light absorption and Raman spectroscopy show that the change in particle nanostructure follows a graphitization trajectory as the flame richness increases. The optical band gap decreases and the size of the aromatic network in the particle increases, while the interlayer spacing between parallel layers decreases. The electrical conductivity of the materials increases by increasing flame richness in agreement to the graphitization trajectory. A non-ohmic behavior has been found and explained in terms of electron tunneling in a percolative network. Our results show that the electrical properties of flame formed carbon nanoparticles are strongly dependent on their nanostructure, and hence they have to be used carefully for the determination of particle concentration with conductometric sensors. Moreover, the dependence of the electrical properties of combustion formed particles might be useful for the development of cheap sensors for the selective detection of different classes of combustion aerosols.     

OPTIMIZED PROCEDURE TO EVALUATE THE THERMAL ENERGY TRANSFER IN HEMODIALYSIS TREATMENT

Hemodialysis treatment is biased by complications during its operative phases. One of these potential accidents consists in intradialytic hypotension, that causes discomfort to the patient and may even increase the risk of death. Therefore, it is very important to predict these events in routine clinical procedures. A cause of hypotension may be thermal energy/heat exchanges between extracorporeal system and the surrounding environment. A model to evaluate these heat losses is proposed and improved in order to maintain constant patient blood temperature. A convenient procedure is defined to improve and optimize clinical treatment. Although most hemodialysis machines automatically control the dialysate solution temperature starting from peripheral body temperature measurements, the proposed method is based on the control of the pre-dialysis core temperature of the patient, and the temperature of the blood entering the artery from the extracorporeal circuit after the treatment in the dialyzer. Measurements of arterial and venous blood temperatures are obtained in a non invasive way by a suitable estimate of the thermal energy exchanges between the blood and the environment during the extracorporeal recirculation. The suggested model guarantees a constant core temperature of the patient, improving prevention from intradialytic hypotension.     

High-speed single cable synchronization system for data-converters

A clock-cycle accurate synchronization technique for fully integrated data-converters is presented. Only a single cable is needed to distribute both the required synchronization signal and the converter clock. Different possible implementations, both to generate and decompose the distributed signal, are presented. A discrete component generator circuit is discussed. To avoid setup and hold time violations, on-chip signal reconstruction is unavoidable. A 40 nm CMOS recovery circuit was developed. Simulation results, including layout parasitics, show the wide frequency operating range of the proposed technique.     

Social Exclusion in Later Life: A Systematic Review of the Literature

In the last decade, there has been a growing awareness regarding social exclusion. Considering the ageing population and the likelihood of older people being socially excluded, the aims of this article are to: (1) review existing studies concerning social exclusion in later life; and (2) identify how environmental and life-course perspectives are presented in studies focusing on social exclusion in later life. A systematic review in seven scientific databases was conducted to explore the peer-reviewed evidence. In total, 26 articles were included and analysed. Findings describe the variety of methods, conceptualisation, dimensions and measures used in this recent area of research. Determinants of social exclusion in later life are discussed and life-course and environmental perspectives are examined. The discussion highlights the complex character of the concept and measurement of social exclusion, and the presence of general and age-specific dimensions of social exclusion in later life. The time and context relativity and the need for life-course and environmental perspectives on social exclusion in later life are discussed. Finally, future directions of research are discussed.     

Cycling reliability of RF-MEMS switches with Gold–Platinum multilayers as contact material

Microsystem Technologies - Contact resistance is the main parameter used for assessing the high cycling reliability of RF microelectromechanical (RF-MEMS) switches. In this paper the use of a...     

Antioxidant activities of chestnut nut of Castanea sativa Mill. (cultivar ‘Judia’) as function of origin ecosystem

The antioxidant properties of different ecotypes of chestnut nut (cv. Judia) were studied. Total phenolics and flavonoids were also determinated. Total phenolics amount ranged from 9.6 mg/g of GAE (hottest ecotype, Murça) to 19.4 mg/g of GAE (coldest ecotype, Valpaços). Gallic and ellagic acid were the predominant compounds and Valpaços had the highest values while, Murça had the lowest ones. The antioxidant capacity of ethanolic extracts were evaluated through several biochemical essays: ABTS (2,2′-azinobis-(3-ethylbenzothiazoline-6-sulphonic acid)) and DPPH (2,2-diphenyl-1-picrylhydrazyl) radical-scavenging activity, FRAP (ferric reducing/antioxidant power) and inhibition of oxidative haemolysis in erythrocytes. In order to evaluate the antioxidant efficiency of each ecotype, the EC₅₀ values were calculated. Once again Valpaços revealed the best antioxidant properties, presenting much lower EC₅₀ values. Climatic conditions influence seems to be a limiting factor for production of phenolic compounds and consequently for the antioxidant properties of chestnut nuts.     

Analysis of Grain Boundary Character in a Fine-Grained Nickel-Based Superalloy 718

In the current work, sheets of superalloy 718 were processed via thermomechanical route by hot and cold rolling, followed by annealing below the δ phase solvus temperature and precipitation hardening to optimum strength. Grain boundary character distribution throughout the processing was mapped via EBSD and its evolution discussed. The results show that it is possible to process the alloy to a fine grain size obtaining concomitantly a considerably high proportion of special boundaries Σ3, Σ9, and Σ27. The precipitation of δ phase presented a strong grain refining role, without significantly impairing the twinning mechanism and, consequently, the Σ3, Σ9, and Σ27 boundary formations.