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•Wash primers with zinc tannates inhibit in the same way as those with phosphates.•Alkyd paints with zinc tannates provide an outstanding anticorrosive protection.•Alkyd primers with ...zinc tannates developed the best adhesion.•Zinc tannates’ protection mechanism involves the formation of iron tannates.•Environments with low corrosivity favoured zinc tannates’ protection mechanism.
The aim of this research was to evaluate the anticorrosive properties of alkyd paints and wash primers formulated with zinc tannates containing Tara tannins. Their inhibitory efficiency was compared with paints pigmented with well-known anticorrosive pigments by accelerated corrosion tests (salt spray test, Prohesion test, and sulphur dioxide test), natural exposure tests and some electrochemical techniques (corrosion potential, polarization resistance and impedance measurements). It was demonstrated that the capacity of inhibiting corrosion of zinc tannates is equivalent to that shown by most commercially available conventional pigments, such as zinc phosphate and zinc chromate.
•The humidity chamber could not differentiate between the protective behavior of different water-borne epoxy coatings.•Results from impedance measurements do not correlate with those from the ...humidity chamber and those from salt spray test.•Anticorrosive behavior depends on the resin and slightly on the anticorrosive pigment.•Outdoor exposure results only correlated with those from impedance measurements.
One of the most inexpensive and effective method to protect steel against corrosion is paints containing active pigments. The traditional way to test these coatings performance is by accelerated tests (exposition to salt spray and/or humidity chambers) and electrochemical tests (corrosion potential, ionic resistance and electrochemical impedance spectroscopy). However, these tests give incomplete information if the results are not correlated to outdoor or service tests.
The aim of this work was to evaluate water-borne epoxy anticorrosion paints containing different commercial phosphate pigments. The paints were exposed to a semi-industrial atmosphere for 7 years. Electrochemical tests and accelerated assays were also done in order to find a correlation between laboratory and service tests.
The results obtained showed no correlation between those from pigment suspensions and those from painted panels, as it seemed that paint performance is highly dependent on the resin. The pigments zinc iron phosphate and zinc aluminium phosphate performed poorly in pigment suspensions. However, the coatings containing them exhibited the highest ionic resistance, the lowest film capacitance and gave the better results in outdoor tests. Results in outdoor exposure tests correlated with those from impedance measurements.
•Biocolonization of painted surfaces causes health problems and reduces its useful life.•Melamine-formaldehyde microcapsules containing essential oils were obtained.•Waterborne coating with ...microcapsules-essential oil was successfully developed.•Innovative waterborne coating protects indoor surfaces from Aspergillus fumigatus.
There is a great concern about the indoor microbial colonization especially in places that should have high standards of environmental hygiene. Besides, due it shortened the useful life of the coating by discoloration and degradation. Currently this is a problem that must be solved in an innovative and eco-friendly way. In this sense, the aim of the work was to develop a green waterborne paint formulated with microcapsules containing essentials oil as biocide agent. This novel hygienic coating would be applied as to protect indoor surfaces from fungi. The microcapsules were synthesized by interfacial polymerization. Melamine-formaldehyde (MF) resin was used for the microcapsule shell wall, and Lavandin and Tea Tree essential oils (EOs) as core materials. The synthesized microcapsules were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy and particle size analysis. Preparation of acrylic waterborne paint was performed and the microcapsules MF-EOs were dispersed into the original paint just before application on commercial gypsum boards. The stability of the MF-EOs in the paint was successfully achieved. Two control paints were used, one containing EOs in free form and other without biocide.
The effectiveness of the microcapsules into paint film against spore suspension of Aspergillus fumigatus was evaluated by seeding the fungus on the painted surface. The fungal growth was evaluated according to ASTM D5590 standard specification. The score obtained from MF-Lavandin paint indicates just a trace growth onto the painted surface (<10 %). On the control and MF-Tea tree paints the growth was 70 %. The MF-Lavandin showed a high inhibition activity against fungal in the dry paint film compared with the one containing free form EOs paint.
•Metal nanoparticles were studied as fungal inhibitors in paints.•The silver smaller size nanoparticles were the most effective ones.•Two fungi, isolated from contaminated paints, were used as ...aggressive fungi.•The gloss of the paints did not change with the addition of the nanoparticles.•Color changes only appeared in the case of higher concentrations of silver.
There are nanotechnology-based materials that can be used as antimicrobial additives in different applications such as water-borne paints. Antimicrobial paints are important tool in order to avoid indoor biological colonization and therefore prevent paint bio-deterioration and health problems in people and pets. These paints would have application in kitchens, bathrooms and hospitals. The present study evaluated the incorporation of silver (of two different sizes), copper and zinc oxide nanoparticles in indoor waterborne paints and the bio-resistance imparted by them. The antifungal activity of nanoparticles is a less studied topic in relation to the antibacterial activity but is no less important from the environmental point of view. Molds that grow in indoor environments contribute significantly with bioaerosol formation and therefore on air contamination and human health deterioration. In this sense, this research evaluated the nanoparticles’ antifungal activity using previously isolated fungi, Chaetomium globosum and Alternaria alternata, on solid medium. Then, the bio-resistance of acrylic paints, with nanoparticles incorporated, was evaluated in Petri dishes and observations were made using scanning electron microscopy. The better results were obtained with the paint that contained silver with the smaller size (10nm).
Steel panels must be protected during storage and transportation because they can corrode. This protection used to be afforded by chromate primers, but nowadays tannin-based primers are being ...studied. These primers are not only used as protection but also as adhesion promoter if the steel surface was not well prepared (presence of oxides or low roughness).
The objective of this work was to prepare lanthanum “tannate”, employing tara and quebracho tannins. The “tannates” were incorporated in primers formulation and applied on steel SAE 1010 panels (previously exposed to the humidity chamber or with 6 μm of roughness depth). These primed panels were exposed to humidity chamber where corrosion and blistering degrees were evaluated. Adhesion test were done. Electrochemical assays such as ionic resistance and corrosion potential measurements were carried out.
Results showed that the adhesion and the barrier properties of the primers were good. Besides, on low roughness steel, the primers diminished the corrosion current.
Results were compared with traditional zinc tetroxychromate primer.
The aim of the study was to evaluate safety and efficacy of IP in LT, particularly in marginal grafts. From 2007 to 2008, 75 LT donors were randomized to receive IP (IP+) or not (IP–). Considering ...the graft quality, we divided the main groups in two subgroups (marg+/marg–). IP was performed by 10‐min inflow occlusion (Pringle maneuver utilizing a toruniquet). Donor variables considered were gender, age, AST/ALT, ischemia time and steatosis. Recipient variables were gender, age, indication to LT and MELD/CHILD/UNOS score. AST/ALT levels, INR, bilirubin, lactic acid, bile output on postoperative days 1, 3 and 7 were evaluated. Histological analysis was performed evaluating necrosis/steatosis, hepatocyte swelling, PMN infiltration and councilman bodies. Thirty patients received IP+ liver. No differences were seen between groups considering recipient and donor variables. Liver function and AST/ALT levels showed no significant differences between the main two groups. Marginal IP+ showed lower AST levels on day1 compared with untreated marginal livers (936.35 vs. 1268.23; p = 0.026). IP+ livers showed a significant reduction of moderate‐severe hepatocyte swelling (33.3% vs. 65.9%; p = 0.043). IP+ patients had a significant reduction of positive early microbiological investigations (36.7% vs. 57.1%; p = 0.042). In our experience IP was safe also in marginal donors, showing a protective role against IRI.
This prospective randomized study showed the safety and efficacy of ischemic preconditioning in liver transplantation, evaluating its correlation to clinical and histological improvement of both optimal and marginal preconditioned grafts.
In a typical urban configuration, a microclimatic analysis has been carried out. Using a CFD method, a N-S oriented urban street canyon, with a given H W ratio, has been examined. The standard k- ...turbulence model has been used to simulate a three-dimensional flow field and to calculate the thermo-fluid dynamics parameters that characterize the street canyon. In this study has been analyzed the thermal flow field when the walls of the building change the properties of solar radiation absorption, in particular for α=0.2 and α=0.8. Solar radiation considered is that of 21 07 in Milan in two different hours: at 11:00 a.m. and at 02:00 p.m. The study shows the importance of the thermophysical properties of a wall, in the development of the thermal field and flow field. This is a very important topic, in terms of improvement of wellbeing and the quality of the air within the cities, through the choice of materials and colors of the facades of buildings.
Machine perfusion (MP) has been shown worldwide to offer many advantages in liver transplantation, but it still has some gray areas. The purpose of the study is to evaluate the donor risk factors of ...grafts, perfused with any MP, that might predict an ineffective MP setting and those would trigger post-transplant early allograft dysfunction (EAD). Data from donors of all MP-perfused grafts at six liver transplant centers have been analyzed, whether implanted or discarded after perfusion. The first endpoint was the negative events after perfusion (NegE), which is the number of grafts discarded plus those that were implanted but lost after the transplant. A risk factor analysis for NegE was performed and marginal grafts for MP were identified. Finally, the risk of EAD was analyzed, considering only implanted grafts. From 2015 to September 2019, 158 grafts were perfused with MP: 151 grafts were implanted and 7 were discarded after the MP phase because they did not reach viability criteria. Of 151, 15 grafts were lost after transplant, so the NegE group consisted of 22 donors. In univariate analysis, the donor risk index >1.7, the presence of hypertension in the medical history, static cold ischemia time, and the moderate or severe macrovesicular steatosis were the significant factors for NegE. Multivariate analysis confirmed that macrosteatosis >30% was an independent risk factor for NegE (odd ratio 5.643,
p
= 0.023, 95% confidence interval, 1.27–24.98). Of 151 transplanted patients, 34% experienced EAD and had worse 1- and 3-year-survival, compared with those who did not face EAD (NoEAD), 96% and 96% for EAD vs. 89% and 71% for NoEAD, respectively (
p
= 0.03). None of the donor/graft characteristics was associated with EAD even if the graft was moderately steatotic or fibrotic or from an aged donor. For the first time, this study shows that macrovesicular steatosis >30% might be a warning factor involved in the risk of graft loss or a cause of graft discard after the MP treatment. On the other hand, the MP seems to be useful in reducing the donor and graft weight in the development of EAD.
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