Acute toxicity of aqueous extract of Ambrosia arborescens Mill. on biochemical and histopathological parameters in rats

Silva-Correa Carmen R.,Villarreal-La Torre Víctor E.,González-Siccha Anabel D.,Cruzado-Razco José L.,González-Blas María V.,Sagástegui-Guarniz William Antonio,Calderón-Peña Abhel A.,Aspajo-Villalaz Ci 한국독성학회 2022 Toxicological Research Vol.38 No.2

Medicinal plants play an important role in the management of various diseases, so their use has become widespread. However, in some cases the population uses plant species regardless of the toxicity they may possess. The objective of this study was to evaluate the acute toxicity of aqueous extract from the leaves of Ambrosia arborescens Mill. on the biochemical and histopathological parameters of albino Holtzman rats. To do this, the leaves of A. arborescens were collected in the province of Julcan, La Libertad Region—Peru. OECD (Organisation for Economic Cooperation and Development) guideline 423 was conducted, forming experimental groups of 10 animals each one (5 males and 5 females): Group I (Control), which received 2 mL physiological saline solution (SSF 0.9%), Groups II and III (A. arborescens-300 and A. arborescens-2000), which were given the aqueous extract leaves of A. arborescens in a single dose of 300 and 2000 mg/kg/day, respectively. On the 14th day of exposure, biochemical (creatinine, ALT and AST) and histopathological parameters were measured. The results show that the aqueous extract of A. arborescens at the dose of 2000 mg/kg produces an increase in biochemical parameters which is related to histopathological analysis of liver and renal tissue with mild congestion. The study concludes that the aqueous extract leaves of A. arborescens has a LD50 greater than 2000 mg/kg and produces mild congestion in kidneys and liver, but showed no significant toxicological changes in the other albino Holtzman rats organs.

Improved Mg–Al–Zn Magnesium Alloys Produced by High Energy Milling and Hot Sintering

Y. Galindez,E. Correa,A. A. Zuleta,A. Valencia‑Escobar,D. Calderon,L. Toro,P. Chacón,F. Echeverría E. 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.5

Powders of commercially pure magnesium (c.p. Mg), AZ91 magnesium alloy and zinc were milled using a high-energy mill.The effect of high energy milling (HEM) on powders morphology, chemical composition, crystallite size and compactionof different powders mixtures were studied. After compaction, samples were thermally treated at 450 °C and both densityand hardness were evaluated. It was found that as milling speed and time increases, the AZ91 alloy and c.p. Mg particleswere deformed and fractured up to sizes below 10 μm. X-ray diffraction patterns for both the c.p. Mg and the AZ91 powdersrevealed that the milling process induced changes in both the α-Mg and the β-Mg17Al12 phases. By increasing the millingspeed, the crystallite size decreases by up to 70% for AZ91 powders and by 80% for magnesium powders. The relativedensities of the compacted AZ samples were greater than 85% and this parameter increased for all samples after thermaltreatment at 450 °C, obtaining densities higher than 88%. Hardness measurements disclosed values as high as 84.3 HR15T.Theoretical calculations of mechanical strength were obtained for all samples based on the hardness values measured, findingvery encouraging results for the three Mg alloys.

Effect of pH on Dimethylamine Borane Reduced Electroless Nickel Deposits on AISI/SAE 1045 Steel Surface

L. Guerra,F. Echeverría,E. Correa 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.6

Electroless Ni–B coatings using DMAB-reduced plating baths at different pH conditions were formed on AISI/SAE 1045carbon steel. Substrates were grit-blasted with alumina, generating a rough surface suitable for anchorage and nucleationof the coating. The surface of the substrates were examined at selected times of electroless treatment using scanning electronmicroscopy. The structure of the coating was studied by means of X-ray diffraction. A low-cost boron determinationprocedure was implemented in order to determine the amount of boron incorporated into the electroless coatings. Coatingsnucleate faster at acid and neutral pH conditions; however, at the end of the plating process all coatings were adherent, withthe typical morphology of Ni–B electroless coatings. Substrates slightly corroded inside the plating bath at acid pH condition. The amount of boron into the coatings was approximately 2.15, 2.14 and 1.10% (wt%) for the acid, neutral and alkalinepH plating baths, respectively.

Prediction of optoelectronic features and efficiency for CuMX2 (M=Ga, In; X=S, Se) semiconductors using mbj+U approximation

Bikerouin M.,Balli M.,Correa J.D.,Mora-Ramos M.E. 한국물리학회 2021 Current Applied Physics Vol.32 No.-

The optoelectronic properties of a selected group of Cu-III-VI2 chalcopyrites-based materials are deeply investigated by using the modified Becke-Johnson (mBJ) potential, combined with DFT + U approach. The obtained results are further used to calculate these materials’ theoretical efficiency limit for solar cell applications. The bandgap findings indicate a reliable ±0.2 eV agreement. After evaluating the electronic and optical properties, the spectroscopic limited maximum efficiency (SLME) model was used as a metric for the screening. Besides the bandgap value considered in the Shockley–Queisser model, the SLME requires that the absorption spectra, the radiative recombination losses, and the absorber layer thickness must be considered to adequately calculate the efficiency of considered cells. Our findings unveil that some candidates, such as CuInS2, where an SLME of 30.25% is achieved at a film width of 500 nm can be classified in the category of materials with higher power conversion efficiency.

Comparison of Methodologies to Quantify Phytate Phosphorus in Diets Containing Phytase and Excreta from Broilers

de P. Naves, L.,Rodrigues, P.B.,Bertechini, A.G.,Correa, A.D.,de Oliveira, D.H.,de Oliveira, E.C.,Duarte, W.F.,da Cunha, M.R.R. Asian Australasian Association of Animal Productio 2014 Animal Bioscience Vol.27 No.7

The use of a suitable methodology to quantify the phytate phosphorus ($P_{phy}$) content in both the feed and the excreta from broilers is required to enable accurate calculation of the catalytic efficiency of the phytase supplemented in the feed. This study was conducted to compare 2 analytical methodologies (colorimetry and also high-performance liquid chromatography with a refractive index detector) in order to calculate the phytase efficiency by utilizing the results from the methodology that was shown to be the most appropriate. One hundred and twenty broilers were distributed in a $(4+1){\times}2$ factorial arrangement, corresponding to 4 diets that were equally deficient in P supplemented with increasing levels of phytase (0, 750, 1,500, and 2,250 units of phytase activity - FTU - per kg of feed) plus 1 positive control diet without phytase, supplied to male and female birds. The result indicated that the colorimetric methodology with an extraction ratio of 1:20 (mass of sample in g:volume of the solvent extractor in mL) was shown to be the most adequate. There was no interaction between the phytase level and the sex of the broilers (p>0.05). Males consumed 12% more $P_{phy}$ than did females (p<0.01), but the sex of the broilers did not affect (p>0.05) the excretion and retention coefficient of $P_{phy}$. The increase in the phytase level of the diet reduced (linear, p<0.01) the $P_{phy}$ excretion. The greatest $P_{phy}$ retention was estimated at 87.85% when the diet contained 1,950 FTU/kg (p<0.01), indicating that it is possible to reduce the inorganic P in the formulation at an amount equivalent to 87.85% of the $P_{phy}$ content present in the feed, which, in this research, corresponds to a decrease in 2.86 g of P/kg of the feed.

Accuracy of various imaging methods for detecting misfit at the tooth-restoration interface in posterior teeth

Francio, Luciano Andrei,Silva, Fernanda Evangelista,Valerio, Claudia Scigliano,Cardoso, Claudia Assuncao e Alves,Jansen, Wellington Correa,Manzi, Flavio Ricardo Korean Academy of Oral and Maxillofacial Radiology 2018 Imaging Science in Dentistry Vol.48 No.2

Purpose: The present study aimed to evaluate which of the following imaging methods best assessed misfit at the tooth-restoration interface: (1) bitewing radiographs, both conventional and digital, performed using a photostimulable phosphor plate (PSP) and a charge-coupled device (CCD) system; (2) panoramic radiographs, both conventional and digital; and (3) cone-beam computed tomography (CBCT). Materials and Methods: Forty healthy human molars with class I cavities were selected and divided into 4 groups according to the restoration that was applied: composite resin, composite resin with liner material to simulate misfit, dental amalgam, and dental amalgam with liner material to simulate misfit. Radiography and tomography were performed using the various imaging methods, and the resulting images were analyzed by 2 calibrated radiologists. The true presence or absence of misfit corresponding to an area of radiolucency in regions subjacent to the esthetic and metal restorations was validated with microscopy. The data were analyzed using a receiver operating characteristic (ROC) curve, and the scores were compared using the Cohen kappa coefficient. Results: For bitewing images, the digital systems (CCD and PSP) showed a higher area under the ROC curve (AUROC) for the evaluation of resin restorations, while the conventional images exhibited a larger AUROC for the evaluation of amalgam restorations. Conventional and digital panoramic radiographs did not yield good results for the evaluation of resin and amalgam restorations (P<.05). CBCT images exhibited good results for resin restorations(P>.05), but showed no discriminatory ability for amalgam restorations(P<.05). Conclusion: Bitewing radiographs (conventional or digital) should be the method of choice when assessing dental restoration misfit.

Intermetallic-Rich Layer Formation for Improving Corrosion Resistance of Magnesium Alloys

D. Calderón,Y. Galindez,L. Toro,A. A. Zuleta,A. Valencia‑Escobar,P. Chacón,E. Correa,F. Echeverría 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.3

The present work examines the formation of a corrosion protective coating containing intermetallic phases on magnesiumalloy substrates. The protective coating was formed on the surfaces of commercially pure magnesium (cp Mg) and AZ31Bmagnesium alloy by vacuum thermal evaporation of commercially pure aluminium (cp Al) and a subsequent heat treatmentof the sample. This coating was continuous, homogenous and its microstructure was a eutectic phase composed by clustersof α-Mg surrounded by β phase (Mg17Al12). This eutectic-type coating provided 168 and 504 h of protection inside the saltspray chamber for the cp Mg and AZ31 alloy samples, respectively. To achieve this, it was required to deposit at least 5.5 μmof cp Al and then perform a combined thermal treatment involving heating the samples to 583 K for 60 min and then raisingthe temperature to 693 K for 5 min.