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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.
Surface Protection Obtained by Anodic Oxidation of New Ti-Ta-Zr Alloy
( C. Vasilescu ),( S. I. Drob ),( J. M. Calderon Moreno ),( P. Drob,M. Popa ),( E. Vasilescu ) 한국부식방식학회(구 한국부식학회) 2018 Corrosion Science and Technology Vol.17 No.2
A new 80Ti-15Ta-5Zr wt% alloy surface was protected by anodic oxidation in phosphoric acid solution. The protective oxide layer (TiO<sub>2</sub>, ZrO<sub>2</sub> and Ta suboxides and thickness of 15.5 nm) incorporated PO<sub>4</sub> <sup>3-</sup> ions from the solution, according to high resolution XPS spectra. The AFM analysis determined a high roughness with SEM detected pores (20 - 50 nm). The electrochemical studies of bare and anodically oxidized Ti-15Ta-5Zr alloy in Carter-Brugirard saliva of different pH values and saliva with 0.05M NaF, pointed to a nobler surface for the protected alloy, with a thicker electrodeposited oxide layer acting as a barrier against aggressive ions. The oxidized alloy significantly decreased corrosion current densities and total quantity of ions released into the oral environment in comparison with the bare one, at higher polarisation resistance and protective capacity of the electrodeposited layer. The impedance data revealed a bi-layered oxidation film formed by: a dense, compact, barrier layer in contact with the metallic substrate, decreasing the potential gradient across the metal/oxide layer/solution interface, reducing the anodic dissolution and a more permissive, porous layer in contact with the electrolyte. The open circuit potential for protected alloy shifted to nobler values, with thickening of the oxidation film signifying long-term protection.
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.
( J. M. Calderon Moreno ),( P. Drob ),( C. Vasilescu ),( S. I. Drob ),( M. Popa ),( E. Vasilescu ) 한국부식방식학회(구 한국부식학회) 2017 Corrosion Science and Technology Vol.16 No.5
Film of new Ti-15Zr-5Nb alloy formed during galvanic anodizing in orthophosphoric acid solution was characterized by optical microscope, scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and Raman micro-spectroscopy. Its anticorrosive properties were determined by electrochemical techniques. The film had a layer with nanotube-like porosity with diameters in 500-1000 nm range. The nano layer contained significant amounts of P and O as well as alloying element. Additionally, Raman micro-spectroscopy identified oxygen as oxygen ion in TiO<sub>2</sub> anatase and phosphorous as P<sub>2</sub>O<sub>7</sub><sup>4-</sup> ion in phosphotitanate compound. All potentiodynamic polarization curves in artificial Carter-Brugirard saliva with pH values (pH= 3.96, 7.84, and 9.11) depending on the addition of 0.05M NaF revealed nobler behavior of anodized alloy and higher polarization resistance indicating the film is thicker and more compact nanolayer. Lower corrosion rates of the anodized alloy reduced toxicity due to less released ions into saliva. Bigger curvature radii in Nyquist plot and higher phase angle in Bode plot for the anodized alloy ascertain a thicker, more protective, insulating nanolayer existing on the anodized alloy. Additionally, ESI results indicate anodized film consists of an inner, compact, barrier, layer and an outer, less protective, porous layer.
Economic Significance of Non-Timber Forest Products as a Sustainable Source of Rural Livelihoods
Himayatullah Khan,Laura G. Vasilescu,Branka Buric 세계문화관광학회 2009 Conference Proceedings Vol.10 No.0
Human societies derive many essential goods from natural ecosystems, including seafood, game animals, fodder, fuel wood, timber, and pharmaceutical products. These goods represent important and familiar parts of the economy. Non-timber forest products (NTFPs) are an important forest resource in Pakistan, with the potential to make a significant economic contribution to small, resource-based communities. Non-timber forest products include all the human-exploited uses of plant and fungal species of the forest, other than timber, pulpwood, shakes or other wood products. The commercial harvest of NTFPs from forest lands is a significant economic activity in Pakistan and in some areas it is important to rural economic development. This study is based on a sample of 209 households in three selected villages of District Abbottabad. The data were collected using a pre-tested interview schedule in spring 2008. This study investigates the role of common property resources as a source of sustainable rural income in Ayubia National Park. No study has ever been conducted in Pakistan on the role of NTFPs collected from the forests in ANP area. This study was conducted to examine the extent of dependency of households on NTFPs as family income; the relative contribution of NTFPs in annual family income; category wise variation of NTFP collection among households, if any; the type of NTFP collected by villagers; and trend of NTFP collection for sale, etc. The study finds that family size and family type contributed positively to NTFPs income and labour employment, landholdings and agricultural income and cost of technology contributing negatively to NTFPs dependence.
( Himayatullah Khan ),( Laura G. Vasilescu ),( Branka Buric ) 한국문화관광학회 2009 문화관광연구 Vol.11 No.2
Human societies derive many essential goods from natural ecosystems, including seafood, game animals, fodder, fuel wood, timber, and pharmaceutical products. These goods represent important and familiar parts of the economy. Non-timber forest products (NTFPs) are an important forest resource in Pakistan, with the potential to make a significant economic contribution to small, resource-based communities. Non-timber forest products include all the human-exploited uses of plant and fungal species of the forest, other than timber, pulpwood, shakes or other wood products. The commercial harvest of NTFPs from forest lands is a significant economic activity in Pakistan and in some areas it is important to rural economic development. This study is based on a sample of 209 households in three selected villages of District Abbottabad. The data were collected using a pre-tested interview schedule in spring 2008. This study investigates the role of common property resources as a source of sustainable rural income in Ayubia National Park. No study has ever been conducted in Pakistan on the role of NTFPs collected from the forests in ANP area. This study was conducted to examine the extent of dependency of households on NTFPs as family income; the relative contribution of NTFPs in annual family income; category wise variation of NTFP collection among households, if any; the type of NTFP collected by villagers; and trend of NTFP collection for sale, etc. The study finds that family size and family type contributed positively to NTFPs income and labour employment, landholdings and agricultural income and cost of technology contributing negatively to NTFPs dependence.
Lindoy, L.F.,Meehan, G.V.,Vasilescu, I.M.,Kim, H.J.,Lee, J.E.,Lee, S.S. Elsevier Publishing Company 2010 Coordination chemistry reviews Vol.254 No.15
The transition and post-transition metal ion chemistry of a wide range of potentially pentadentate dibenzo-substituted macrocyclic ligands incorporating nitrogen, oxygen and/or sulfur donors is reviewed and shown to result in a diverse range of structural types. Aspects of metal ion recognition, bulk membrane transport, systems incorporating appended chromophores, a sulfate binding system, induced Cu(I)/Cu(II) redox switching, coordination polymers, and unsymmetric macrocyclic ligand systems are all discussed.
Martiniuc, Alexandru,Dumitrascu, Traian,Ionescu, Mihnea,Tudor, Stefan,Lacatus, Monica,Herlea, Vlad,Vasilescu, Catalin The Korean Gastric Cancer Association 2021 Journal of gastric cancer Vol.21 No.1
Purpose: Incidence, risk factors, and clinical consequences of pancreatic fistula (POPF) after D1+/D2 radical gastrectomy have not been well investigated in Western patients, particularly those from Eastern Europe. Materials and Methods: A total of 358 D1+/D2 radical gastrectomies were performed by surgeons with high caseloads in a single surgical center from 2002 to 2017. A retrospective analysis of data that were prospectively gathered in an electronic database was performed. POPF was defined and graded according to the International Study Group for Pancreatic Surgery (ISGPS) criteria. Uni- and multivariate analyses were performed to identify potential predictors of POPF. Additionally, the impact of POPF on early complications and long-term outcomes were investigated. Results: POPF was observed in 20 patients (5.6%), according to the updated ISGPS grading system. Cardiovascular comorbidities emerged as the single independent predictor of POPF formation (risk ratio, 3.051; 95% confidence interval, 1.161-8.019; P=0.024). POPF occurrence was associated with statistically significant increased rates of postoperative hemorrhage requiring re-laparotomy (P=0.029), anastomotic leak (P=0.002), 90-day mortality (P=0.036), and prolonged hospital stay (P<0.001). The long-term survival of patients with gastric adenocarcinoma was not affected by POPF (P=0.661). Conclusions: In this large series of Eastern European patients, the clinically relevant rate of POPF after D1+/D2 radical gastrectomy was low. The presence of co-existing cardiovascular disease favored the occurrence of POPF and was associated with an increased risk of postoperative bleeding, anastomotic leak, 90-day mortality, and prolonged hospital stay. POPF was not found to affect the long-term survival of patients with gastric adenocarcinoma.
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).