A numerical study of fatigue crack closure induced by plasticity

Crack closure delays the intrinsic mechanisms responsible for crack growth, therefore, it must be considered in fatigue crack growth modelling. The objective of this work is to develop a numerical procedure to predict crack closure induced by plasticity. First the crack closure was experimentally measured on M(T) 6082‐T6 aluminium alloy specimens of 3 mm thickness. A pin microgauge was used with the compliance technique. Then different parameters of the numerical procedure were analysed, namely the finite element mesh and the crack propagation scheme. The size of crack‐tip elements has an important influence and it is recommended to be of the same order of cyclic plastic zone. Crack‐opening levels only 10% lower than experimental results were obtained considering kinematic hardening and two load cycles in each increment.     

Mesenchymal stem cell secretome and nanotechnology: Combining therapeutic strategies

Mesenchymal stem cells (MSC) have pushed the field of stem cell-based therapies by inducing tissue regeneration, immunosuppression, and angiogenesis mainly through vesicles and soluble factors release (paracrine signaling). MSC-extracellular vesicles (MSC-EV) adaptable secretome and homing to injured sites allowed researchers to unlock a new era of cell-free based therapy. In parallel, nanoparticles (NP) have been explored in contributing to transport and drug delivery systems, giving drugs desired physical-chemical properties to exploit cell behavior. However, NPs can be quickly recognized by immune cells and cleared from circulation. In this viewpoint, we explore how combining both therapeutic strategies can improve efficacy and circumvent limitations of both therapies. MSCEV benefit from the potent MSC membrane composition, guiding chemotaxis to tumor sites, a very restricted microenvironment. MSC-EV has low immunogenicity, high stability, long half-life and can explore tissue targeting ligands as a precise drug carry, even across biological barriers. Those properties promote enhanced targeted drug delivery that can be combined with NP, exploring biological membrane production through: 1. direct cell therapy with NP-infused MSC; 2. NP-containing MSC-EV generated by NP-infused MSC; 3. by coating NP in MSC membrane (“MSC NanoGhosts”), allowing precise cargo definition without losing targeting. Therefore, nanotechnology combined with cell-based therapeutic resources can greatly improve targeted drug delivery, improving efficacy and opening a new venue of therapeutic possibilities.     

Consumer rejection threshold of ethyl phenylacetate and phenylacetic acid,compounds responsible for the sweet‐like off odour in wines made from sour rotten grapes

Backgrounds and Aims: This study aimed to determine a consumer rejection threshold (CRT) for ethyl phenylacetate (EPhA) and phenylacetic acid (PhAA) in wine. These compounds have recently been reported to be responsible for sweet‐like, honey off odours in wine made from sour rotten grapes. Methods and Results: Non‐expert wine consumers (n = 35) received pairs of samples comprising a control wine against a spiked wine with an ascending concentration of the target compounds and were asked to indicate which sample they preferred. Results estimated a conjoint CRT for EPhA and PhAA of 140 and 700 µg/L, respectively. Wines spiked with a EPhA and PhAA concentration around the CRT evoked intense ‘dried fruit’ aromas that led to a decrease of the general aroma quality; these wines are significantly rejected by consumers. Conclusions: The measured CRT provides an initial estimation of the risk concentration for EPhA and PhAA in red wine, as they represent a ‘taint’ for regular wine consumers. Significance of the Study: These data allow wine producers to predict if a given wine will be disliked by consumers or to help guide ‘blending away’ of such wines.     

DNA mismatch repair gene methylation in gastric cancer in individuals from northern Brazil

Gastric cancer is one of the most common malignancies. DNA methylation is implicated in DNA mismatch repair genes deficiency. In the present study, we evaluated the methylation status of MLH1, MSH2, MSH6 and PMS2 in 20 diffuse- and 26 intestinal-type gastric cancer samples and 20 normal gastric mucosal of gastric cancer patients from Northern Brazil. We found that none of the nonneoplastic samples showed methylation of any gene promoter and 50% of gastric cancer samples showed at least one methylated gene promoter. Methylation frequencies of MLH1, MSH2, MSH6 and PMS2 promoter were 21.74%, 17.39%, 0% and 28.26% respectively in gastric cancer samples. MLH1 and PMS2 methylation were associated with neoplastic samples compared to nonneoplastic ones. PMS2 methylation was associated with diffuse- and intestinal-type cancer compared with normal controls. Intestinal-type cancer showed significant association with MLH1 methylation. Diffuse-type cancer was significantly associated with MSH2 methylation. Our findings show differential gene methylation in tumoral tissue, which allows us to conclude that methylation is associated with gastric carcinogenesis. Methylation of mismatch repair genes was associated with gastric carcinogenesis and may be a helpful tool for diagnosis, prognosis and therapies. However, MSH6 does not seem to be regulated by methylation in our samples.     

The effects of copper and high sugar concentrations on growth, fermentation efficiency and volatile acidity production of different commercial wine yeast strains

The effect of high sugar concentrations or the presence of copper residues on fermentation efficiency and volatile acid (VA) production were examined for selected commercial wine yeast strains. Fermentation rate as measured by accumulated mass loss appeared to be least affected by high sugar concentrations during the first few days of fermentation for strains VIN13, WE14, N96 and RJ11. It was, however, only fermentations using VIN13, WE372, N96 and L2056 that contained less than 11 g/L fructose after 21 days. VIN13 and RJ11 produced the lowest VA in the 21^o, 25^o and 28^oBrix musts. Fermentation efficiency of six strains was also studied in must containing 0.25 mM Cu²⁺. Results indicated that strains NT50, Collection Cépage Cabernet (CC) and D80 were not significantly affected, whereas VIN13, NT112 and RJ11 contained significantly more glucose and fructose after fermentation in the must containing copper. Copper addition also increased VA production, with strains RJ11 and NT50 being the most affected.