The sialotranscriptomes of
revealed a transcript overexpressed in female salivary glands that codes a mature 7.8 kDa peptide. The peptide, specific to the
genus, has a unique sequence, presents a ...putative secretory nature and its function is unknown. Here, we confirmed that the peptide is highly expressed in the salivary glands of female mosquitoes when compared to the salivary glands of males, and its secretion in mosquito saliva is able to sensitize the vertebrate host by inducing the production of specific antibodies. The synthetic version of the peptide downmodulated nitric oxide production by activated peritoneal murine macrophages. The fractionation of a
salivary preparation revealed that the fractions containing the naturally secreted peptide reproduced the nitric oxide downmodulation. The synthetic peptide also selectively interfered with cytokine production by murine macrophages, inhibiting the production of IL-6, IL-12p40 and CCL2 without affecting TNF-α or IL-10 production. Likewise, intracellular proteins associated with macrophage activation were also distinctively modulated: while iNOS and NF-κB p65 expression were diminished, IκBα and p38 MAPK expression did not change in the presence of the peptide. The anti-inflammatory properties of the synthetic peptide were tested
on a dextran sulfate sodium-induced colitis model. The therapeutic administration of the
peptide reduced the leukocytosis, macrophage activity and nitric oxide levels in the gut, as well as the expression of cytokines associated with the disease, resulting in amelioration of its clinical signs. Given its biological properties
and
, the molecule was termed
-specific
dulatory
ptide (AeMOPE-1). Thus, AeMOPE-1 is a novel mosquito-derived immunobiologic with potential to treat immune-mediated disorders.
The corrosion behavior of borided X12CrNiMoV12-3 steel immersed during 5 days in a 0.1 M NaCl + 0.04 M Na
2
SO
4
aqueous solution was obtained. The boride layer (FeB/Fe
2
B) formed on the surface of ...the material was developed using the powder-pack boriding process at 1223 K during 6 hours of exposure. Some corrosion electrochemical parameters such as the polarization resistance, the current density, the anodic and cathodic Tafel slopes were determined by means of the potentiodynamic polarization technique, in which the corrosion resistance values of the borided stainless steel were compared with those estimated for the non-borided X12CrNiMoV12-3 steel (reference material).The corrosion behavior of the borided X12CrNiMoV12-3 steel was associated with the development of B
2
S
3
and Fe
2
O
3
on the surface of the boride layer as well as for the presence of texture fibers such as {020}//ND and {021}//ND (estimated from crystallographic texture analysis), which drastically reduced the corrosion resistance values of the boride layer exposed to the aqueous solution. Finally, the electrochemical reactions produced during the immersion of the borided X12CrNiMoV12-3 steel in the neutral chloride-sulfate aqueous solution were proposed.
Interfacial indentation test of FeB/Fe2B coatings Campos-Silva, I.; Martínez-Trinidad, J.; Doñu-Ruíz, M.A. ...
Surface & coatings technology,
12/2011, Letnik:
206, Številka:
7
Journal Article, Conference Proceeding
Recenzirano
The present study uses interfacial indentation testing to estimate the adhesion of the FeB/Fe2B coating formed on the surface of borided AISI 316 steel. This technique creates and propagates a crack ...along the FeB/Fe2B interface and defines the apparent fracture toughness, which can then be related to the adhesion and mechanical support of the aforementioned interface. The boriding process was performed on the surface of AISI 316 steel by means of the powder-pack method at temperatures of 1123, 1173, 1223 and 1273K with 2, 4, 6, 8 and 10h for each temperature. The Young's modulus for each surface layer was obtained by Knoop microindentation at a constant indentation load. Vickers microindentation fracture technique was used to generate microcracks at the FeB/Fe2B interface with varying indentation loads. The applied load, Young's modulus, hardness, and lateral crack lengths generated from the corners of the indentations, along with the depth of the FeB layer, were used to determine the apparent fracture toughness and adhesion of the FeB/Fe2B interface. The apparent fracture toughness of the FeB/Fe2B interface varied between 3.56 and 4.45MPa m. Finally, the intensity of residual stress at the FeB/Fe2B interface was estimated as a function of the FeB layer thickness.
► The adhesion of the FeB/Fe2B interface was estimated by Vickers indentation ► The fracture resistance at the interface was related to the FeB layer thickness ► Compressive residual stresses in the borided interface were estimated by indentation
Novel findings of boride layer adhesion resistance on AISI D2 steel after post-heat treatments were obtained using scratch tests. The boride layer on the steel was developed using powder-pack ...boriding assisted by a pulsed-DC field, with a constant temperature and exposure time and a current of 5A. In addition, the electrical resistivity behavior of the powder mixture was evaluated both before and during the boriding treatment. The results indicate that the post-heat treatments had a significant effect on the microstructure of the layer-substrate system. When a monophasic Fe
2
B layer was combined with a mixed martensite–bainite microstructure in the substrate, the scratch resistance was found to be almost twofold superior to the layer that was not exposed to the post-heat treatments.
Aims: To evaluate the effect of wine phenolic compounds on the production of volatile phenols (4-vinylphenol 4VP and 4-ethylphenol 4EP) from the metabolism of p-coumaric acid by lactic acid bacteria ...(LAB). Methods and Results: Lactobacillus plantarum, Lactobacillus collinoides and Pediococcus pentosaceus were grown in MRS medium supplemented with p-coumaric acid, in the presence of different phenolic compounds: nonflavonoids (hydroxycinnamic and benzoic acids) and flavonoids (flavonols and flavanols). The inducibility of the enzymes involved in the p-coumaric acid metabolism was studied in resting cells. The hydroxycinnamic acids tested stimulated the capacity of LAB to synthesize volatile phenols. Growth in the presence of hydroxycinnamic acids, especially caffeic acid, induced the production of 4VP by resting cells. The hydroxybenzoic acids did not significantly affect the behaviour of the studied strains. Some of the flavonoids showed an effect on the production of volatile phenols, although strongly dependent on the bacterial species. Relatively high concentrations (1 g l⁻¹) of tannins inhibited the synthesis of 4VP by Lact. plantarum. Conclusions: Hydroxycinnamic acids were the main compounds stimulating the production of volatile phenols by LAB. The results suggest that caffeic and ferulic acids induce the synthesis of the cinnamate decarboxylase involved in the metabolism of p-coumaric acid. On the other hand, tannins exert an inhibitory effect. Significance and Impact of the Study: This study highlights the capacity of LAB to produce volatile phenols and that this activity is markedly influenced by the phenolic composition of the medium.
In this study, the fracture toughness of the Fe2B layer was estimated using the Berkovich indentation technique. Boron diffusion at the surface of the AISI 1018 steel was conducted using a ...powder-pack boriding process at a temperature of 1273K with 6h of exposure. The mechanical characterization of the Fe2B layer was performed on three different distances from the surface using a range of indentation loads (10 to 500mN) for each distance. The behavior of the hardness as a function of the indentation load showed the presence of the indentation size effect (ISE) at the different distances from the surface, in which the apparent or real hardness was estimated according to the concept of the Nix and Gao model. Finally, two indentation-cracking models were used to estimate the fracture toughness of the Fe2B layer on the different distances from the surface; the results were ranged from 1.5 to 4.2 MPa m1/2, which denoted the brittleness and the influence of the anisotropic nature of the boride layer.
•The fracture toughness along the depth of the Fe2B layer was evaluated.•The apparent hardness of the boride layer was established by the GND theory.•The fracture resistance of the Fe2B layer is a function of the indentation distance.
An experimental and numerical study of the scratch test on FeB/Fe2B bilayers is presented. The boride layers were formed at the surface of AISI 304 steels by developing the powder-pack boriding ...process at temperatures of 1223K for 2, 6 and 10h of exposure times. From the set of experimental conditions of the boriding process, scratch tests were performed with a linearly-increasing load mode of 1 to 90N on 7mm in length to determinate the most effective and informative testing conditions and to estimate the critical load (Lc) at which the boride layer fails. The damage in the boride layer was examined by high resolution SEM. Experiments tests indicated that at a critical load the boride layer fails through brittle fracture. Numerical calculations considering the residual stress field generated by the scratch load showed that at this load the tensile stresses inside the boride layer become large enough to cause brittle failure. The residual stress fields generated by the scratch load were analyzed and related with the failure mechanisms observed by the experimental tests.
•Scratch tests on boride layers were evaluated using the finite element method.•Normal and shear stresses during the scratch test were analyzed.•Cohesive and adhesion failures were observed in the boride layers.
New results about the growth kinetics of CoB–Co
B layers developed at the surface of CoCrMo alloy using the powder-pack boriding process assisted by a direct current field (PBDCF) were estimated in ...this work. The PBDCF was conducted at temperatures of 1048 – 1148 K with different exposure times for each temperature, whereas the growth kinetics of the cobalt boride layers was modelled using a system of two differential equations. In addition, indentation properties such as hardness, Young’s modulus and residual stresses were estimated along the depth of the borided CoCrMo surface. The growth kinetics of the cobalt boride layers developed by PBDCF indicated that thicker boride layers were formed on the material’s surface which was in contact to the current field at the anode, in contrast to the surface exposed at the cathode. The kinetics of cobalt boride layers were compared with those obtained by conventional powder-pack boriding process.
In this study, the indentation properties of the Fe2B layer were evaluated. The powder-pack boriding process on low-carbon steels was carried out at a temperature of 1273K for 4, 6 and 8h of ...exposure. First, Vickers indentation testing was performed on the boride layer at a distance of 50μm from the surface of the borided steel with applied loads in the range of 0.0981 to 9.81N for the set of experimental conditions of the boriding process. Furthermore, the hardness–depth profile, the behavior of the Young's modulus, and the elastic and plastic work of indentation were estimated by the instrumented (Berkovich) indentation testing using a constant load of 250 mN along the depth of the Fe2B layer. The results of the Vickers hardness testing on 50 μm from the surface indicated the presence of the indentation size effect (ISE) in the boride layer, in which the apparent or real hardness was estimated according to the proportional specimen resistance (PSR) model, and the dislocation band (DB) model. Finally, using the results of the instrumented indentation tests along the depth of the boride layer, the thermal residual stresses and the hardness dissipation parameter (HDP) were evaluated as a function of the boriding temperature and exposure time.
•Indentation tests were used to evaluate mechanical properties of the Fe2B layer.•The real hardness of the boride layer was estimated on 50microns from the surface.•The H/E ratio can be established to explain the wear resistance of the Fe2B layer.
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