Influence of skin-layer microstructure in ultrafast laser surface treatment

In this work, the morphology of AISI 316L stainless steel surfaces, textured with ultrafast laser machining, was studied by scanning probe microscopy. In particular, correlations between the morphology and the polycrystalline microstructure of the material were searched. Topographic maps of the treated surfaces revealed a transition from small-sized to larger size and rather irregular features, driven by increase in laser fluence and depending on process parameters. In addition, a metrological analysis of the material grains demonstrated a shape and size similarity with laser-induced features attained for certain process parameters, suggesting that surface texture turns influenced by the microstructure of the skin-layer

Real CO2 emissions benefits and end user’s operating costs of a plug-in Hybrid Electric Vehicle

Although plug-in Hybrid Electric Vehicles (pHEVs) can be considered a powerful technology to promote the change from conventional mobility to e-mobility, their real benefits, in terms of CO2 emissions, depend to a great extent on the average efficiency of their Internal Combustion Engine and on the energy source mix which is used to supply the electrical demand of pHEV. Furthermore the operating cost of the vehicle should also be taken into account in the design process, since it represents the main driver in the customer’s choice. This article has the purpose of assessing, through numerical simulations, the effects of different technology mixes used to produce electrical energy for the battery recharging, of different Internal Combustion Engines on the pHEV performance, and highlighting the main differences with respect to the regulatory test procedure

Influence of ns laser texturing of AISI 316L surfaces for reducing bacterial adhesion

Nanosecond pulsed laser texturing has been performed on stainless steel with the objective of developing surface treatments to reduce bacterial adhesion on mechanical components in food handling machinery. The adhesion of Escherichia coli (E. coli) on four distinct textures has been investigated with standardised protocols for measurement of antibacterial performance. Surface morphology has been studied in detail for each texture to ascertain the presence of hierarchical structures and determine the role of topography in reducing bacterial adhesion. Despite the absence of sub-micrometric features comparable with bacterial size, this work highlights the crucial role that nanosecond pulsed laser irradiation plays in promoting a thin layer of iron oxide that reduces E. coli adhesion through local repulsive electrostatic interactions

Molecular dynamics model for the antibactericity of textured surfaces

An original model has been developed for the initial stage of bacterial adhesion on textured surfaces. Based on molecular dynamics, the model describes contact between individual bacterial cells in a planktonic state and a surface, accounting for both the mechanical properties of the cells and the physico-chemical mechanisms governing interaction with the substrate. Feasibility of the model is assessed via comparison with experimental results of bacterial growth on stainless steel substrates textured with ultrashort laser pulses. Simulations are performed for two different bacterial species, Staphylococcus aureus and Escherichia coli, on two distinct surface types characterised by elongated ripples and isolated nanopillars, respectively. Calculated results are in agreement with experiment outcomes and highlight the role of mechanical stresses within the cell wall due to deformation upon interaction with the substrate, creating unfavourable conditions for bacteria during the initial phases of adhesion. Furthermore, the flexibility of the model provides insight into the intricate interplay between topography and the physico-chemical properties of the substrate, pointing to a unified picture of the mechanisms underlying bacterial affinity to a textured surface

Predicting cognitive decline in patients with hypoxaemic COPD

AbstractThe objective was to identify predictors of cognitive decline in patients with hypoxaemic COPD on continuous oxygen therapy.Eighty-four consecutive ambulatory hypoxaemic COPD patients in stable clinical conditions were prospectively studied over the course of 2 yr. Baseline multidimensional assessment included respiratory function tests, blood gas analysis, Mini Mental Status (MMS) test, Geriatric Depression Scale (GDS), Activities of Daily Living (ADLs) and Charlson's index of comorbidity. Reassessments were made 1 yr and 2 yr thereafter. Sequential changes in MMS, GDS and ADLs were assessed by Friedman's ANOVA by rank test.Forty patients completed the study (group A), while 44 died or were lost to follow-up (group B). Group B was characterized by more severe respiratory function impairment and worse performances on ADLs and GDS. In group A, MMS deteriorated from baseline to the 1 yr and 2 yr reassessments (27 ± 2·9 vs. 25·8 ± 4·1 and 25·4 ± 4, P<0·005), whereas GDS and ADLs did not change significantly; the 23 patients experiencing a decline of MMS had baseline lower percentage predicted FVC (52·3 ± 17·1 vs. 66·9 ± 13·4, P<0·03) and FEV1 (27·2 ± 8·6 vs. 44 ± 26·8, P<0·02) values and better affective status (GDS score: 11·9 ± 7·7 vs. 16·5 ± 5·6, P<0·04). Two-year changes in MMS and in GDS scores were inversely correlated (Spearman's ρ = −0·32, P = 0·04).Cognitive decline is faster in the presence of severe bronchial obstruction and parallels the worsening of the affective status in COPD patients on oxygen therapy. The onset of depression rather than baseline depressive symptoms seems to be a risk factor for cognitive decline

Repeatability of the ISAAC video questionnaire and its accuracy against a clinical diagnosis of asthma

AbstractThe objective of the study was to evaluate the performance of the International Study of Asthma and Allergies in Childhood (ISAAC) video questionnaire in terms of repeatability and accuracy against a clinical diagnosis of asthma achieved according to the National Heart, Lung and Blood Institute (NHLBI) algorithm.Two hundred and forty-one subjects, aged 13–14 years from two secondary schools in Rome, Italy, were enrolled. Video and written ISAAC questionnaires were completed twice, 3 months apart, by 194 and 190 adolescents, respectively. Two months later, 106 subjects were visited by two physicians blinded to the results of questionnaires.Sixteen subjects were classified as having clinical asthma (CA) at the clinical visit, and eight of them as having clinical active asthma (CAA) on the basis of at least one positive outcome of the NHLBI algorithm. The repeatability of video questionnaire was similar to that of the written questionnaire for items on exercise wheeze and nocturnal cough and, to a lesser degree, for items concerning any wheeze in the past. The video questionnaire showed a worse performance than the written questionnaire for items on asthma attack: K-value (95% CL)=0·59 (0·37–0·80) for video scene no. 5 and K-value (95% CL)=0·86 (0·74–0·98) for written question no. 6. The overall accuracy of the video questionnaire, estimated as a positive answer to any video scene, was lower in terms of sensitivity than that of any written question when CA was used as a gold standard (0·50 vs. 0·81, P=0·025) and increased with respect to CAA (0·75vs. 0·87, P=0·317). The specificity of any video scene was better than that of any written question, independently from the gold standard used.In conclusion, the video questionnaire showed a fairly good accuracy, although slightly lower than that of the written questionnaire and provided sufficiently reliable results. However, samples of subjects from different geographic areas and cultures should be studied in order to conclusively define the performance of the ISAAC video questionnaire

Effect of the rearing substrate on total protein and amino acid composition in black soldier fly

Insects are becoming increasingly relevant as protein sources in food and feed. The Black Soldier Fly (BSF) is one of the most utilized, thanks to its ability to live on many leftovers. Vegetable processing industries produce huge amounts of by-products, and it is important to efficiently rear BSF on different substrates to assure an economical advantage in bioconversion and to overcome the seasonality of some leftovers. This work evaluated how different substrates affect the protein and amino acid content of BSF. BSF prepupae reared on different substrates showed total protein content varying between 35% and 49% on dry matter. Significant lower protein contents were detected in BSF grown on fruit by-products, while higher contents were observed when autumnal leftovers were employed. BSF protein content was mainly correlated to fibre and protein content in the diet. Among amino acids, lysine, valine and leucine were most affected by the diet. Essential amino acids satisfied the Food and Agricultural Organization (FAO) requirements for human nutrition, except for lysine in few cases. BSF could be a flexible tool to bio-convert a wide range of vegetable by-products of different seasonality in a high-quality protein-rich biomass, even if significant differences in the protein fraction were observed according to the rearing substrate