Microstructure, Mechanical Properties, and Corrosion Resistance of Ti-20Zr Alloy in Undoped and NaF Doped Artificial Saliva

Jose M. Calderon Moreno,Monica Popa,Steliana Ivanescu,Cora Vasilescu,Silviu Iulian Drob,Elena Ionela Neacsu,Mihai V. Popa 대한금속·재료학회 2014 METALS AND MATERIALS International Vol.20 No.1

The corrosion behavior of a new, advanced Ti-20Zr alloy with α+β microstructure (determined by opticalmicroscopy, XRD, and SEM) and very good mechanical properties (obtained from the stress-strain curve)is studied in this paper. The composition of the alloy native passive film was determined from a XPS analy-sis and the long-term corrosion resistance in undoped and doped states with 0.05M NaF artificial Carter-Brugi-rard saliva of different pH values, simulating the severe functional conditions of a dental implant, was analyzed byelectrochemical methods. This alloy possesses an advantageous balance between good mechanical resis-tance and plasticity and Young’s modulus and exhibits more favorable electrochemical parameters and cor-rosion resistance than CP Ti due to its more resistant passive layer containing Ti2O3, TiO2, and ZrO2 protectiveoxides. After 1000 h of immersion in saliva, the protective properties of the alloy were enhanced due tothe deposited surface layer that incorporated protective phosphates (shown by SEM and XPS).

Do changes in inflammatory markers predict hepatocellular carcinoma recurrence and survival after liver transplantation?

Lucas Jose Caram,Francisco Calderon,Esteban Masino,Victoria Ardiles,Ezequiel Mauro,Leila Haddad,Juan Pekolj,Jimena Vicens,Adrian Gadano,Eduardo de Santibanes,Martin de Santibanes 한국간담췌외과학회 2022 Annals of hepato-biliary-pancreatic surgery Vol.26 No.1

Backgrounds/Aims: The role of inflammation in malignant cell proliferation has been well described. High values of platelet-to-lymphocyte ratio (PLR) and neutrophil-to-lymphocyte ratio (NLR) as markers of systemic inflammation have shown associations with unfavorable long-term outcomes. The purpose of this study was to determine values of NLR and PLR evaluated prior to and after surgery and their associations with mortality and recurrence rates of liver transplant patients with hepatocellular carcinoma (HCC). Methods: A total of 105 patients with HCC who underwent orthotopic liver transplantation (OLT) were retrospectively reviewed. NLR and PLR values were obtained from complete blood counts prior to and after surgery. Overall survival (OS) and recurrence-free survival (RFS) in relation with delta NLR and PLR were estimated. Results: Serum alpha-fetoprotein levels > 100 ng/mL (p = 0.014) and lymphovascular emboli in the specimen (p = 0.048) were identified to be significant predictors of RFS. Child-Pugh score (p = 0.016) was found to be an independent factor associated with poorer OS. An increasing delta PLR was associated with worse RFS, although it showed no significant association with OS. Conclusions: The analysis of PLR as a continuous variable may predict recurrence outcomes in patients undergoing OLT for HCC. It is more representative than isolated values.

Influence of ruminal degradable intake protein restriction on characteristics of digestion and growth performance of feedlot cattle during the late finishing phase

May, Dixie,Calderon, Jose F.,Gonzalez, Victor M.,Montano, Martin,Plascencia, Alejandro,Salinas-Chavira, Jaime,Torrentera, Noemi,Zinn, Richard A. Korean Society of Animal Sciences and Technology 2014 한국축산학회지 Vol.56 No.4

Two trials were conducted to evaluate the influence of supplemental urea withdrawal on characteristics of digestion (Trial 1) and growth performance (Trial 2) of feedlot cattle during the last 40 days on feed. Treatments consisted of a steam-flaked corn-based finishing diet supplemented with urea to provide urea fermentation potential (UFP) of 0, 0.6, and 1.2%. In Trial 1, six Holstein steers ($160{\pm}10kg$) with cannulas in the rumen and proximal duodenum were used in a replicated $3{\times}3$ Latin square experiment. Decreasing supplemental urea decreased (linear effect, $P{\leq}0.05$) ruminal OM digestion. This effect was mediated by decreases (linear effect, $P{\leq}0.05$) in ruminal digestibility of NDF and N. Passage of non-ammonia and microbial N (MN) to the small intestine decreased (linear effect, P = 0.04) with decreasing dietary urea level. Total tract digestion of OM (linear effect, P = 0.06), NDF (linear effect, P = 0.07), N (linear effect, P = 0.04) and dietary DE (linear effect, P = 0.05) decreased with decreasing urea level. Treatment effects on total tract starch digestion, although numerically small, likewise tended (linear effect, P = 0.11) to decrease with decreasing urea level. Decreased fiber digestion accounted for 51% of the variation in OM digestion. Ruminal pH was not affected by treatments averaging 5.82. Decreasing urea level decreased (linear effect, $P{\leq}0.05$) ruminal N-NH and blood urea nitrogen. In Trial 2, 90 crossbred steers ($468kg{\pm}8$), were used in a 40 d feeding trial (5 steers/pen, 6 pens/treatment) to evaluate treatment effects on final-phase growth performance. Decreasing urea level did not affect DMI, but decreased (linear effect, $P{\leq}0.03$) ADG, gain efficiency, and dietary NE. It is concluded that in addition to effects on metabolizable amino acid flow to the small intestine, depriving cattle of otherwise ruminally degradable N (RDP) during the late finishing phase may negatively impact site and extent of digestion of OM, depressing ADG, gain efficiency, and dietary NE.

RESEARCH : Open Access ; Influence of ruminal degradable intake protein restriction on characteristics of digestion and growth performance of feedlot cattle during the late finishing phase

( Dixie May ),( Jose F Calderon ),( Victor M Gonzalez ),( Martin Montano ),( Alejandro Plascencia ),( Jaime Salinas-chavira ),( Noemi Torrentera ),( Richard A Zinn ) 한국동물자원과학회(구 한국축산학회) 2014 한국축산학회지 Vol.56 No.14

Two trials were conducted to evaluate the influence of supplemental urea withdrawal on characteristics of digestion (Trial 1) and growth performance (Trial 2) of feedlot cattle during the last 40 days on feed. Treatments consisted of a steam-flaked corn-based finishing diet supplemented with urea to provide urea fermentation potential (UFP) of 0, 0.6, and 1.2%. In Trial 1, six Holstein steers (160 ± 10 kg) with cannulas in the rumen and proximal duodenum were used in a replicated 3 × 3 Latin square experiment. Decreasing supplemental urea decreased (linear effect, P ≤ 0.05) ruminal OM digestion. This effect was mediated by decreases (linear effect, P ≤ 0.05) in ruminal digestibility of NDF and N. Passage of non-ammonia and microbial N (MN) to the small intestine decreased (linear effect, P = 0.04) with decreasing dietary urea level. Total tract digestion of OM (linear effect, P = 0.06), NDF (linear effect, P = 0.07), N (linear effect, P = 0.04) and dietary DE (linear effect, P = 0.05) decreased with decreasing urea level. Treatment effects on total tract starch digestion, although numerically small, likewise tended (linear effect, P = 0.11) to decrease with decreasing urea level. Decreased fiber digestion accounted for 51% of the variation in OM digestion. Ruminal pH was not affected by treatments averaging 5.82. Decreasing urea level decreased (linear effect, P ≤ 0.05) ruminal N-NH and blood urea nitrogen. In Trial 2, 90 crossbred steers (468 kg ± 8), were used in a 40 d feeding trial (5 steers/pen, 6 pens/ treatment) to evaluate treatment effects on final-phase growth performance. Decreasing urea level did not affect DMI, but decreased (linear effect, P ≤ 0.03) ADG, gain efficiency, and dietary NE. It is concluded that in addition to effects on metabolizable amino acid flow to the small intestine, depriving cattle of otherwise ruminally degradable N (RDP) during the late finishing phase may negatively impact site and extent of digestion of OM, depressing ADG, gain efficiency, and dietary NE.

Microstructure, Mechanical, and Anticorrosive Properties of a New Ti-20Nb-10Zr-5Ta Alloy Based on Nontoxic and Nonallergenic Elements

Monica Popa,Ecaterina Vasilescu,Paula Drob,Doina Raducanu,Jose Maria Calderon Moreno,Steliana Ivanescu,Cora Vasilescu,Silviu Iulian Drob 대한금속·재료학회 2012 METALS AND MATERIALS International Vol.18 No.4

For an alloy to be suitable for use as an implant material, it must have a low specific weight and Young’s modulus, good mechanical properties that are similar to those of bone, and very good corrosion resistance and biocompatibility. In this study, we have developed a novel Ti-20Nb-10Zr-5Ta alloy that is composed of nontoxic, nonallergenic, corrosion-resistant elements. This alloy has low specific weight and Young’s modulus and good mechanical properties. It has a fine microstructure with a matrix that is mainly composed of the β phase and some α phase due to recrystallization during cooling. It shows elastoplastic behavior with a fairly linear elastic behavior and low Young’s modulus (59 GPa). In addition, its ultimate tensile strength, 0.2% yield strength, and hardness are higher than those of CP Ti, commercial Ti-6Al-4V,and similar β-type alloys. It exhibited a very stable passive state and its electrochemical parameters and corrosion and ion release rates were better than those of CP Ti in Ringer’s solutions of different pH values that simulate the severe functional conditions of an implant; this is attributable to the beneficial influence of the alloying elements and to the better protective properties of the coated passive film.

Surface Analysis, Microstructural, Mechanical and Electrochemical Properties of New Ti-15Ta-5Zr Alloy

Cora Vasilescu,Silviu Iulian Drob,Petre Osiceanu,Paula Drob,Jose Maria Calderon Moreno1,Silviu Preda,Steliana Ivanescu,Ecaterina Vasilescu 대한금속·재료학회 2015 METALS AND MATERIALS International Vol.21 No.2

This paper describes the synthesis of a novel Ti-15Ta-5Zr alloy with an  + β stable, homogeneous, biphasicmicrostructure (by optical microscopy, X-ray diffraction and scanning electron microscopy) and the determinationof its mechanical properties, hardness and a Young’s modulus of 42.2 GPa. The alloy passive film compositionand thickness were analyzed by X-ray photoelectron spectroscopy; a thick, compact native passive filmcontaining the protective oxides of all constituent elements (TiO2, Ta2O5, ZrO2) was identified. The electrochemicalparameters confirmed a nobler behaviour and a more capacitive, resistant passive film on thealloy surface compared to Ti and other existing implant alloys; these facts are due to the alloying elements that,by their oxides stabilize and reinforce the alloy passive film. This passive film thickened in time, which increased itsprotective capacity. The new alloy had no susceptibility to galvanic or local corrosion. Ti-15Ta-5Zr alloyis recommended as an advanced orthopaedic implant material.