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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 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 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.
Laura Dudus,Corina Minciuna,Stefan Tudor,Monica Lacatus,Bogdan Stefan Vasile,Catalin Vasilescu 대한부인종양학회 2024 Journal of Gynecologic Oncology Vol.35 No.2
Objective: To acknowledge that minimally invasive pelvic exenteration is a feasible alternativeto open surger y and potentially identif y prediction factors for patient outcome. Methods: The study was designed as a retrospective single team analysis of 12 consecutivecases, set between Januar y 2008 and Januar y 2022. Results: Six anterior and 6 total pelvic exenterations were performed. A 75% of caseswere treated using a robotic approach. In 4 cases, an ileal conduit was used for urinar yreconstruction. Mean operative time was 360±30.7 minutes. for anterior pelvic exenterationsand 440±40.7 minutes. for total pelvic exenterations and mean blood loss was 350±35 mL. AnR0 resection was performed in 9 cases (75%) and peri-operative morbidity was 16.6%, withno deaths recorded. Median disease-free sur vival was 12 months (10–14) and overall sur vival(OS) was 20 months (1–127). In terms of OS, 50% of patients were still alive 24 monthsafter surger y. Taking into consideration the follow up period,16.6% of females under 50 orabove 70 years old did not reach the cut off and 4 out of 6 patients that failed to reach it werediagnosed with distant metastases or local recurrence (p=0.169). Conclusion: Our experience is ver y much consistent with literature in regard to primar y siteof cancer, post-operative complications, R0 resection and sur vival rates. On the other hand,minimally invasive approach and urinar y reconstruction type were in contrast with citedpublications. Minimally invasive pelvic exenteration is indeed a safe and feasible procedure,providing patients selection is appropriately performed.