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Craciun D, Laszlo EA, Mirza-Rosca JC, Dorcioman G, Geanta V, Voiculescu I, Craciun G, Badea L, Craciun V. Structural Parameters and Behavior in Simulated Body Fluid of High Entropy Alloy Thin Films. Materials (Basel) 2024; 17:1162. [PMID: 38473633 DOI: 10.3390/ma17051162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Revised: 02/23/2024] [Accepted: 02/25/2024] [Indexed: 03/14/2024]
Abstract
The structure, composition and corrosion properties of thin films synthesized using the Pulsed Laser Deposition (PLD) technique starting from a three high entropy alloy (HEA) AlCoCrFeNix produced by vacuum arc remelting (VAR) method were investigated. The depositions were performed at room temperature on Si and mirror-like polished Ti substrates either under residual vacuum (low 10-7 mbar, films denoted HEA2, HEA6, and HEA10, which were grown from targets with Ni concentration molar ratio, x, equal to 0.4, 1.2, and 2.0, respectively) or under N2 (10-4 mbar, films denoted HEN2, HEN6, and HEN10 for the same Ni concentration molar ratios). The deposited films' structures, investigated using Grazing Incidence X-ray Diffraction, showed the presence of face-centered cubic and body-centered cubic phases, while their surface morphology, investigated using scanning electron microscopy, exhibited a smooth surface with micrometer size droplets. The mass density and thickness were obtained from simulations of acquired X-ray reflectivity curves. The films' elemental composition, estimated using the energy dispersion X-ray spectroscopy, was quite close to that of the targets used. X-ray Photoelectron Spectroscopy investigation showed that films deposited under a N2 atmosphere contained several percentages of N atoms in metallic nitride compounds. The electrochemical behavior of films under simulated body fluid (SBF) conditions was investigated by Open Circuit Potential (OCP) and Electrochemical Impedance Spectroscopy measurements. The measured OCP values increased over time, implying that a passive layer was formed on the surface of the films. It was observed that all films started to passivate in SBF solution, with the HEN6 film exhibiting the highest increase. The highest repassivation potential was exhibited by the same film, implying that it had the highest stability range of all analyzed films. Impedance measurements indicated high corrosion resistance values for HEA2, HEA6, and HEN6 samples. Much lower resistances were found for HEN10 and HEN2. Overall, HEN6 films exhibited the best corrosion behavior among the investigated films. It was noticed that for 24 h of immersion in SBF solution, this film was also a physical barrier to the corrosion process, not only a chemical one.
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Affiliation(s)
- Doina Craciun
- National Institute for Laser, Plasma and Radiation Physics, 077125 Măgurele, Romania
| | - Edwin A Laszlo
- Faculty of Physics, Doctoral School of Physics, University of Bucharest, 077125 Măgurele, Romania
| | - Julia C Mirza-Rosca
- Mechanical Engineering Department, University of Las Palmas de Gran Canaria, 35017 Las Palmas de Gran Canaria, Spain
- Materials Engineering and Welding Department, Transilvania University of Brasov, 500036 Brasov, Romania
| | - Gabriela Dorcioman
- National Institute for Laser, Plasma and Radiation Physics, 077125 Măgurele, Romania
| | - Victor Geanta
- Faculty of Material Science and Engineering, National University of Science and Technology Politehnica of Bucharest, 060042 Bucharest, Romania
| | - Ionelia Voiculescu
- Faculty of Material Science and Engineering, National University of Science and Technology Politehnica of Bucharest, 060042 Bucharest, Romania
| | | | - Liviu Badea
- Faculty of Physics, Doctoral School of Physics, University of Bucharest, 077125 Măgurele, Romania
- National R&D Institute for Non-Ferrous and Rare Metals, 077145 Pantelimon, Romania
| | - Valentin Craciun
- National Institute for Laser, Plasma and Radiation Physics, 077125 Măgurele, Romania
- Extreme Light Infrastructure for Nuclear Physics, IFIN-HH, 077125 Măgurele, Romania
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Chiang CC, Xia X, Craciun V, Rocha MG, Camargo SEA, Rocha FRG, Gopalakrishnan SK, Ziegler KJ, Ren F, Esquivel-Upshaw JF. Enhancing the Hydrophobicity and Antibacterial Properties of SiCN-Coated Surfaces with Quaternization to Address Peri-Implantitis. Materials (Basel) 2023; 16:5751. [PMID: 37687444 PMCID: PMC10488823 DOI: 10.3390/ma16175751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 08/14/2023] [Accepted: 08/18/2023] [Indexed: 09/10/2023]
Abstract
Peri-implantitis is a major cause of dental implant failure. This disease is an inflammation of the tissues surrounding the implant, and, while the cause is multi-factorial, bacteria is the main culprit in initiating an inflammatory reaction. Dental implants with silicon carbonitride (SiCN) coatings have several potential advantages over traditional titanium implants, but their antibacterial efficiency has not yet been evaluated. The purpose of this study was to determine the anti-bacterial potential of SiCN by modifying the surface of SiCN-coated implants to have a positive charge on the nitrogen atoms through the quaternization of the surface atoms. The changes in surface chemistry were confirmed using contact angle measurement and XPS analysis. The modified SiCN surfaces were inoculated with Streptococcus mutans (S. mutans) and compared with a silicon control. The cultured bacterial colonies for the experimental group were 80% less than the control silicon surface. Fluorescent microscopy with live bacteria staining demonstrated significantly reduced bacterial coverage after 3 and 7 days of incubation. Scanning electron microscopy (SEM) was used to visualize the coated surfaces after bacterial inoculation, and the mechanism for the antibacterial properties of the quaternized SiCN was confirmed by observing ruptured bacteria membrane along the surface.
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Affiliation(s)
- Chao-Ching Chiang
- Department of Chemical Engineering, College of Engineering, University of Florida, Gainesville, FL 32611, USA; (C.-C.C.)
| | - Xinyi Xia
- Department of Chemical Engineering, College of Engineering, University of Florida, Gainesville, FL 32611, USA; (C.-C.C.)
| | - Valentin Craciun
- National Institute for Lasers, Plasma and Radiation Physics, RO-077125 Magurele, Ilfov, Romania
| | - Mateus Garcia Rocha
- Department of Restorative Dental Sciences, Division of Operative Dentistry, College of Dentistry, University of Florida, Gainesville, FL 32610, USA
| | - Samira Esteves Afonso Camargo
- Department of Comprehensive Oral Healthy, Adams Dental School, University of North Carolina, Chapel Hill, NC 27599, USA
| | | | - Sarathy K. Gopalakrishnan
- Department of Chemical Engineering, College of Engineering, University of Florida, Gainesville, FL 32611, USA; (C.-C.C.)
| | - Kirk J. Ziegler
- Department of Chemical Engineering, College of Engineering, University of Florida, Gainesville, FL 32611, USA; (C.-C.C.)
| | - Fan Ren
- Department of Chemical Engineering, College of Engineering, University of Florida, Gainesville, FL 32611, USA; (C.-C.C.)
| | - Josephine F. Esquivel-Upshaw
- Department of Restorative Dental Sciences, Division of Prosthodontics, College of Dentistry, University of Florida, Gainesville, FL 32610, USA
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Dorcioman G, Grumezescu V, Stan GE, Chifiriuc MC, Gradisteanu GP, Miculescu F, Matei E, Popescu-Pelin G, Zgura I, Craciun V, Oktar FN, Duta L. Hydroxyapatite Thin Films of Marine Origin as Sustainable Candidates for Dental Implants. Pharmaceutics 2023; 15:pharmaceutics15041294. [PMID: 37111781 PMCID: PMC10142946 DOI: 10.3390/pharmaceutics15041294] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 04/12/2023] [Accepted: 04/14/2023] [Indexed: 04/29/2023] Open
Abstract
Novel biomaterials with promising bone regeneration potential, derived from rich, renewable, and cheap sources, are reported. Thus, thin films were synthesized from marine-derived (i.e., from fish bones and seashells) hydroxyapatite (MdHA) by pulsed laser deposition (PLD) technique. Besides the physical-chemical and mechanical investigations, the deposited thin films were also evaluated in vitro using dedicated cytocompatibility and antimicrobial assays. The morphological examination of MdHA films revealed the fabrication of rough surfaces, which were shown to favor good cell adhesion, and furthermore could foster the in-situ anchorage of implants. The strong hydrophilic behavior of the thin films was evidenced by contact angle (CA) measurements, with values in the range of 15-18°. The inferred bonding strength adherence values were superior (i.e., ~49 MPa) to the threshold established by ISO regulation for high-load implant coatings. After immersion in biological fluids, the growth of an apatite-based layer was noted, which indicated the good mineralization capacity of the MdHA films. All PLD films exhibited low cytotoxicity on osteoblast, fibroblast, and epithelial cells. Moreover, a persistent protective effect against bacterial and fungal colonization (i.e., 1- to 3-log reduction of E. coli, E. faecalis, and C. albicans growth) was demonstrated after 48 h of incubation, with respect to the Ti control. The good cytocompatibility and effective antimicrobial activity, along with the reduced fabrication costs from sustainable sources (available in large quantities), should, therefore, recommend the MdHA materials proposed herein as innovative and viable solutions for the development of novel coatings for metallic dental implants.
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Affiliation(s)
- Gabriela Dorcioman
- Lasers Department, National Institute for Lasers, Plasma and Radiation Physics, 077125 Magurele, Romania
| | - Valentina Grumezescu
- Lasers Department, National Institute for Lasers, Plasma and Radiation Physics, 077125 Magurele, Romania
| | - George E Stan
- National Institute of Materials Physics, 077125 Magurele, Romania
| | - Mariana Carmen Chifiriuc
- Department of Microbiology, Faculty of Biology, University of Bucharest, 060101 Bucharest, Romania
- Earth, Environmental and Life Sciences Division, Research Institute of the University of Bucharest (ICUB), 060101 Bucharest, Romania
- Romanian Academy, 010071 Bucharest, Romania
| | - Gratiela Pircalabioru Gradisteanu
- Earth, Environmental and Life Sciences Division, Research Institute of the University of Bucharest (ICUB), 060101 Bucharest, Romania
- Academy of Romanian Scientists, 051157 Bucharest, Romania
| | - Florin Miculescu
- Faculty of Materials Science and Engineering, Politehnica University of Bucharest, 060042 Bucharest, Romania
| | - Elena Matei
- National Institute of Materials Physics, 077125 Magurele, Romania
| | - Gianina Popescu-Pelin
- Lasers Department, National Institute for Lasers, Plasma and Radiation Physics, 077125 Magurele, Romania
| | - Irina Zgura
- National Institute of Materials Physics, 077125 Magurele, Romania
| | - Valentin Craciun
- Lasers Department, National Institute for Lasers, Plasma and Radiation Physics, 077125 Magurele, Romania
| | - Faik Nüzhet Oktar
- Department of Bioengineering, Faculty of Engineering, University of Marmara, 34722 Istanbul, Turkey
- Advanced Nanomaterials Research Laboratory (ANRL), University of Marmara, 34722 Istanbul, Turkey
| | - Liviu Duta
- Lasers Department, National Institute for Lasers, Plasma and Radiation Physics, 077125 Magurele, Romania
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Ramdane H, Benaioun N, Guezzoul M, Moulayat N, Craciun V. Investigation of the corrosion-preventing properties of nickel-coated austenitic stainless steel (AISI 304) in NaOH and NaOH + 10% NaCl solutions. INORG CHEM COMMUN 2023. [DOI: 10.1016/j.inoche.2023.110671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
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Roy M, Sarkar K, Som J, Pfeifer MA, Craciun V, Schall JD, Aravamudhan S, Wise FW, Kumar D. Modulation of Structural, Electronic, and Optical Properties of Titanium Nitride Thin Films by Regulated In Situ Oxidation. ACS Appl Mater Interfaces 2023; 15:4733-4742. [PMID: 36625508 DOI: 10.1021/acsami.2c18926] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Epitaxial titanium nitride (TiN) and titanium oxynitride (TiON) thin films have been grown on sapphire substrates using a pulsed laser deposition (PLD) method in high-vacuum conditions (base pressure <3 × 10-6 T). This vacuum contains enough residual oxygen to allow a time-independent gas phase oxidation of the ablated species as well as a time-dependent regulated surface oxidation of TiN to TiON films. The time-dependent surface oxidation is controlled by means of film deposition time that, in turn, is controlled by changing the number of laser pulses impinging on the polycrystalline TiN target at a constant repetition rate. By changing the number of laser pulses from 150 to 5000, unoxidized (or negligibly oxidized) and oxidized TiN films have been obtained with the thickness in the range of four unit cells to 70 unit cells of TiN/TiON. X-ray photoelectron spectroscopy (XPS) investigations reveal higher oxygen content in TiON films prepared with a larger number of laser pulses. The oxidation of TiN films is achieved by precisely controlling the time of deposition, which affects the surface diffusion of oxygen to the TiN film lattice. The lattice constants of the TiON films obtained by x-ray diffraction (XRD) increase with the oxygen content in the film, as predicted by molecular dynamics (MD) simulations. The lattice constant increase is explained based on a larger electrostatic repulsive force due to unbalanced local charges in the vicinity of Ti vacancies and substitutional O. The bandgap of TiN and TiON films, measured using UV-visible spectroscopy, has an asymmetric V-shaped variation as a function of the number of pulses. The bandgap variation following the lower number of laser pulses (150-750) of the V-shaped curve is explained using the quantum confinement effect, while the bandgap variation following the higher number of laser pulses (1000-5000) is associated with the modification in the band structure due to hybridization of O2p and N2p energy levels.
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Affiliation(s)
- Manosi Roy
- Department of Mechanical Engineering, North Carolina A&T State University, 1601 E Market St, Greensboro, North Carolina27411, United States
| | - Kaushik Sarkar
- Department of Mechanical Engineering, North Carolina A&T State University, 1601 E Market St, Greensboro, North Carolina27411, United States
| | - Jacob Som
- Department of Mechanical Engineering, North Carolina A&T State University, 1601 E Market St, Greensboro, North Carolina27411, United States
| | - Mark A Pfeifer
- Cornell Center for Materials Research, Cornell University, Clark Hall, 627, 142 Sciences Dr, Ithaca, New York14850, United States
| | - Valentin Craciun
- National Institute for Laser, Plasma and Radiation Physics, Strada Atomiştilor 409, Bucharest, Magurele077125, Romania
| | - J David Schall
- Department of Mechanical Engineering, North Carolina A&T State University, 1601 E Market St, Greensboro, North Carolina27411, United States
| | - Shyam Aravamudhan
- Joint School of Nanoscience and Nanoengineering, North Carolina A&T State University, Greensboro, North Carolina27401, United States
| | - Frank W Wise
- Cornell Center for Materials Research, Cornell University, Clark Hall, 627, 142 Sciences Dr, Ithaca, New York14850, United States
| | - Dhananjay Kumar
- Department of Mechanical Engineering, North Carolina A&T State University, 1601 E Market St, Greensboro, North Carolina27411, United States
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Udrea R, Irimiciuc SA, Craciun V. Subthreshold Laser Ablation Measurements by Langmuir Probe Method for ns Irradiation of HfO 2 and ZrO 2. Materials (Basel) 2023; 16:536. [PMID: 36676270 PMCID: PMC9861943 DOI: 10.3390/ma16020536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 12/22/2022] [Accepted: 12/22/2022] [Indexed: 06/17/2023]
Abstract
The unbiased Langmuir probe (LP) method was used to perform measurements on HfO2 and ZrO2 samples around the laser ablation threshold on a wide range of irradiation conditions. Important changes in the lifetime (from ms to μs) and the shape of the charge particle current were seen with the increase of the laser fluence. The ablation threshold was estimated by evaluating the overall average ablated charge as a function of the laser fluence. Above the ablation threshold, the generation of high kinetic species is seen, which can reach several keV. An important jump in ion acceleration potential is observed for values above 1 J/cm2, which coincides with the dominant presence of negative ions in the plasma. The evolution of several plasma parameters (ion density, expansion velocity, electron temperature, Debye length) was investigated and correlated with the fundamental ablation mechanism involved in various irradiation regimes. The LP data were correlated with COMSOL simulations on the maximum surface temperature reached during irradiation. Important correlations between the evaporation and melting processes and ablation threshold fluence and ion acceleration phenomena are also reported.
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Affiliation(s)
- Radu Udrea
- Apel Laser, Street Vanatorilor 25, Mogosoaia, 077135 Ilfov, Romania
- Physics Faculty, University of Bucharest, 077125 Magurele, Romania
| | | | - Valentin Craciun
- National Insitute for Lasers Plasma and Radiation Physics, 077125 Magurele, Romania
- Extreme Light Infrastructure for Nuclear Physics, 077125 Magurele, Romania
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Irimiciuc SA, Chertopalov S, Novotný M, Craciun V, Lancok J. On the Dynamics of Transient Plasmas Generated by Nanosecond Laser Ablation of Several Metals. Materials (Basel) 2021; 14:ma14237336. [PMID: 34885492 PMCID: PMC8658669 DOI: 10.3390/ma14237336] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 11/24/2021] [Accepted: 11/26/2021] [Indexed: 11/16/2022]
Abstract
The dynamics of transient plasma generated by UV ns-laser ablation of selected metals (Co, Cu, Ag, Bi) were investigated by the Langmuir Probe method in angle- and time-resolved modes. Multiple ionic and electronic structures were seen for all plasmas with some corresponding to anions or nanoparticle-dominated structures. The addition of an Ar atmosphere energetically confined the plasma and increased the charge density by several orders of magnitude. For pressure ranges exceeding 0.5 Pa fast ions were generated in the plasma as a result of Ar ionization and acceleration in the double layer defining the front of the plasma plume. Several correlations between the target nature plasma properties were attempted. The individual plasma structure expansion velocity increases with the melting point and decreases with the atomic mass while the corresponding charged particle densities decrease with the melting point, evidencing the relationship between the volatility of the sample and the overall abated mass.
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Affiliation(s)
- Stefan Andrei Irimiciuc
- National Institute for Laser, Plasma and Radiation Physics—NILPRP, 409 Atomistilor Street, 077125 Magurele, Romania;
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 182 00 Prague, Czech Republic; (M.N.); (J.L.)
- Correspondence: (S.A.I.); (S.C.)
| | - Sergii Chertopalov
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 182 00 Prague, Czech Republic; (M.N.); (J.L.)
- Correspondence: (S.A.I.); (S.C.)
| | - Michal Novotný
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 182 00 Prague, Czech Republic; (M.N.); (J.L.)
| | - Valentin Craciun
- National Institute for Laser, Plasma and Radiation Physics—NILPRP, 409 Atomistilor Street, 077125 Magurele, Romania;
- Extreme Light Infrastructure for Nuclear Physics, IFIN-HH, 077125 Magurele, Romania
| | - Jan Lancok
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 182 00 Prague, Czech Republic; (M.N.); (J.L.)
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Taleb A, Motto-Ros V, Carru MJ, Axente E, Craciun V, Pelascini F, Hermann J. Measurement error due to self-absorption in calibration-free laser-induced breakdown spectroscopy. Anal Chim Acta 2021; 1185:339070. [PMID: 34711325 DOI: 10.1016/j.aca.2021.339070] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 09/03/2021] [Accepted: 09/14/2021] [Indexed: 11/15/2022]
Abstract
Self-absorption of spectral lines is known to lower the performance of analytical measurements via calibration-free laser-induced breakdown spectroscopy. However, the error growth due to this effect is not clearly assessed. Here we propose a method to quantify the measurement error due to self-absorption based on the calculation of the spectral radiance of a plasma in local thermodynamic equilibrium. Validated through spectroscopic measurements for a binary alloy thin film of compositional gradient, the method evidences that measurement performance lowering due to self-absorption depends on the spectral shape of the analytical transition and on the intensity measurement method. Thus, line-integrated intensity measurements of Stark broadened lines enable accurate analysis, even at large optical thickness, if line width and plasma size are precisely known. The error growth due to self-absorption is significantly larger for line shapes dominated by Doppler broadening and for line-center intensity measurements. The findings present a significant advance in compositional measurements via calibration-free laser-induced breakdown spectroscopy, as they enable straightforward selection of most appropriate analytical lines.
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Affiliation(s)
- Aya Taleb
- Aix-Marseille University, CNRS, LP3, 13288, Marseille, France; Cetim Grand Est, 67400, Illkirch-Graffenstaden, France
| | - Vincent Motto-Ros
- University Lyon 1, CNRS, Institut Lumière Matière, 69622, Villeurbanne, France
| | - Mauro J Carru
- Aix-Marseille University, CNRS, LP3, 13288, Marseille, France
| | - Emanuel Axente
- National Institute for Laser, Plasma and Radiation Physics, 77125, Mǎgurele, Romania
| | - Valentin Craciun
- National Institute for Laser, Plasma and Radiation Physics, 77125, Mǎgurele, Romania
| | | | - Jörg Hermann
- Aix-Marseille University, CNRS, LP3, 13288, Marseille, France.
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Mogildea M, Mogildea G, Craciun V, Zgura SI. The Effects Induced by Microwave Field upon Tungsten Wires of Different Diameters. Materials (Basel) 2021; 14:ma14041036. [PMID: 33671682 PMCID: PMC7926306 DOI: 10.3390/ma14041036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 02/16/2021] [Accepted: 02/18/2021] [Indexed: 11/16/2022]
Abstract
The effects induced by microwave field upon tungsten wires of different diameters were investigated. Tungsten wires with 0.5 and 1.0 mm diameters were placed in the focal point of a single-mode cylindrical cavity linked to a microwave generator and exposed to microwave field in ambient air. The experimental results showed that the 0.5 mm diameter wire was completely vaporized due to microwaves strong absorption, while the wire with 1 mm diameter was not ignited. During the interaction between microwaves and tungsten wire with 0.5 mm diameter, a plasma with a high electronic excitation temperature was obtained. The theoretical analysis of the experiment showed that the voltage generated by metallic wires in interaction with microwaves depended on their electric resistance in AC and the power of the microwave field. The physical parameters and dimension of the metallic wire play a crucial role in the ignition process of the plasma by the microwave field. This new and simple method to generate a high-temperature plasma from a metallic wire could have many applications, especially in metal oxides synthesis, metal coatings, or thin film deposition.
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Affiliation(s)
- Marian Mogildea
- Institute of Space Science, MG-36, 077125 Magurele, Romania; (M.M.); (S.I.Z.)
| | - George Mogildea
- Institute of Space Science, MG-36, 077125 Magurele, Romania; (M.M.); (S.I.Z.)
- Correspondence:
| | - Valentin Craciun
- National Institute for Laser, Plasma and Radiation Physics, Laser Department, 409 Atomistilor St., 077125 Magurele, Romania;
- Extreme Light Infrastructure for Nuclear Physics, ELI-NP, HH-IFIN, 077125 Magurele, Romania
| | - Sorin I. Zgura
- Institute of Space Science, MG-36, 077125 Magurele, Romania; (M.M.); (S.I.Z.)
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Prepelita P, Garoi F, Craciun V. Structural and optical characteristics determined by the sputtering deposition conditions of oxide thin films. Beilstein J Nanotechnol 2021; 12:354-365. [PMID: 33968560 PMCID: PMC8077636 DOI: 10.3762/bjnano.12.29] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 04/03/2021] [Indexed: 05/16/2023]
Abstract
The influence of film thickness on the structural and optical properties of silicon dioxide (SiO2) and zinc oxide (ZnO) thin films deposited by radio frequency magnetron sputtering on quartz substrates was investigated. The deposition conditions were optimized to achieve stoichiometric thin films. The orientation of crystallites, structure, and composition were investigated by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), while the surface topography of the samples was analyzed using scanning electron microscopy (SEM). The optical characteristics were measured for samples with the same composition but obtained with different deposition parameters, such as increasing thickness. The optical constants (i.e., the refractive index n, the extinction coefficient k, and the absorption coefficient α) of the SiO2 and ZnO oxide films were determined from the transmission spectra recorded in the range of 190-2500 nm by using the Swanepoel method, while the energy bandgap was calculated from the absorption spectra. The influence of thickness on the structural and optical properties of the oxide films was investigated. Good optical quality and performance were noticed, which makes these thin films worthy of integration into metamaterial structures.
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Affiliation(s)
- Petronela Prepelita
- National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-36, Magurele 077125, Ilfov, Romania
| | - Florin Garoi
- National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-36, Magurele 077125, Ilfov, Romania
| | - Valentin Craciun
- National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-36, Magurele 077125, Ilfov, Romania
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Constantin G, Balan E, Voiculescu I, Geanta V, Craciun V. Cutting Behavior of Al 0.6CoCrFeNi High Entropy Alloy. Materials (Basel) 2020; 13:ma13184181. [PMID: 32962284 PMCID: PMC7560482 DOI: 10.3390/ma13184181] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 09/15/2020] [Accepted: 09/16/2020] [Indexed: 11/16/2022]
Abstract
There is an increased interest in high entropy alloys as a result of the special possibilities of improving the mechanical, physical or chemical characteristics resulting from metallic matrices made of different chemical elements added in equimolar proportions. The next step in developing new alloys is to determine the cutting conditions to optimize manufacturing prescriptions. This article presents a series of tests performed to estimate the machining behavior of the Al0.6CoCrFeNi high entropy alloy. The effects of temperature during machining, wear effects on the cutting tool, evolution of the hardness on the processed areas, cutting force components and resultant cutting force for high entropy alloy (HEA) in comparison with 304 stainless steel, scrap aspect and machined surface quality were analyzed to have an image of the HEA machinability. In terms of cutting forces, the behavior of the HEA was found to be about 59% better than that of stainless steel. XRD analysis demonstrated that the patterns are very similar for as-cast and machined surfaces. The wear effects that appear on the cutting edge faces for the tool made of rapid steel compared to carbide during HEA machining led to the conclusion that physical vapor deposition (PVD)-coated carbide inserts are suitable for the cutting of HEAs.
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Affiliation(s)
- George Constantin
- Robots and Manufacturing Systems Department, University Politehnica of Bucharest, 060042 Bucharest, Romania; (G.C.); (E.B.)
| | - Emilia Balan
- Robots and Manufacturing Systems Department, University Politehnica of Bucharest, 060042 Bucharest, Romania; (G.C.); (E.B.)
| | - Ionelia Voiculescu
- Quality Engineering and Industrial Technologies Department, University Politehnica of Bucharest, 060042 Bucharest, Romania
- Correspondence:
| | - Victor Geanta
- Engineering and Management of Metallic Material Processing Department, University Politehnica of Bucharest, 060042 Bucharest, Romania;
| | - Valentin Craciun
- National Institute for Laser, Plasma and Radiation Physic, 077125 Magurele, Romania;
- Extreme Light Infrastructure-Nuclear Physics, IFIN-HH, 077125 Magurele, Romania
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12
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Hsu SM, Ren F, Batich C, Clark AE, Craciun V, Esquivel-Upshaw JF. Dissolution activation energy of a fluorapatite glass-ceramic veneer for dental applications. Mater Sci Eng C Mater Biol Appl 2020; 111:110802. [PMID: 32279806 PMCID: PMC7282197 DOI: 10.1016/j.msec.2020.110802] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 11/08/2019] [Accepted: 02/29/2020] [Indexed: 12/01/2022]
Affiliation(s)
- S M Hsu
- Restorative Dental Sciences, Division of Prosthodontics, University of Florida, Gainesville, FL, USA.
| | - F Ren
- Department of Chemical Engineering, University of Florida, Gainesville, FL, USA.
| | - C Batich
- Department of Material Science and Engineering, University of Florida, Gainesville, FL, USA.
| | - A E Clark
- Restorative Dental Sciences, Division of Prosthodontics, University of Florida, Gainesville, FL, USA.
| | - V Craciun
- National Institute for Lasers, Plasma and Radiation Physics, Magurele, Ilfov, Romania; DENTIX MILLENNIUM SRL, Sabareni, Giurgiu, Romania.
| | - J F Esquivel-Upshaw
- Restorative Dental Sciences, Division of Prosthodontics, University of Florida, Gainesville, FL, USA.
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13
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Fares C, Elhassani R, Partain J, Hsu SM, Craciun V, Ren F, Esquivel-Upshaw JF. Annealing and N 2 Plasma Treatment to Minimize Corrosion of SiC-Coated Glass-Ceramics. Materials (Basel) 2020; 13:ma13102375. [PMID: 32455653 PMCID: PMC7287612 DOI: 10.3390/ma13102375] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Revised: 05/09/2020] [Accepted: 05/19/2020] [Indexed: 01/25/2023]
Abstract
To improve the chemical durability of SiC-based coatings on glass-ceramics, the effects of annealing and N2 plasma treatment were investigated. Fluorapatite glass-ceramic disks were coated with SiC via plasma-enhanced chemical vapor deposition (PECVD), treated with N2 plasma followed by an annealing step, characterized, and then immersed in a pH 10 buffer solution for 30 days to study coating delamination. Post-deposition annealing was found to densify the deposited SiC and lessen SiC delamination during the pH 10 immersion. When the SiC was treated with a N2 plasma for 10 min, the bulk properties of the SiC coating were not affected but surface pores were sealed, slightly improving the SiC’s chemical durability. By combining N2 plasma-treatment with a post-deposition annealing step, film delamination was reduced from 94% to 2.9% after immersion in a pH 10 solution for 30 days. X-ray Photoelectron spectroscopy (XPS) detected a higher concentration of oxygen on the surface of the plasma treated films, indicating a thin SiO2 layer was formed and could have assisted in pore sealing. In conclusion, post-deposition annealing and N2 plasma treatment where shown to significantly improve the chemical durability of PECVD deposited SiC films used as a coating for glass-ceramics.
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Affiliation(s)
- Chaker Fares
- Chemical Engineering Department, University of Florida College of Engineering, Gainesville, FL 32611, USA; (C.F.); (R.E.); (J.P.); (F.R.)
| | - Randy Elhassani
- Chemical Engineering Department, University of Florida College of Engineering, Gainesville, FL 32611, USA; (C.F.); (R.E.); (J.P.); (F.R.)
| | - Jessica Partain
- Chemical Engineering Department, University of Florida College of Engineering, Gainesville, FL 32611, USA; (C.F.); (R.E.); (J.P.); (F.R.)
| | - Shu-Min Hsu
- Department of Restorative Dental Sciences, University of Florida College of Dentistry, Gainesville, FL 32610, USA;
| | - Valentin Craciun
- Plasma and Radiation Physics, National Institute for Laser, Laser Department, RO-077125 Bucharest, Romania;
| | - Fan Ren
- Chemical Engineering Department, University of Florida College of Engineering, Gainesville, FL 32611, USA; (C.F.); (R.E.); (J.P.); (F.R.)
| | - Josephine F. Esquivel-Upshaw
- Department of Restorative Dental Sciences, University of Florida College of Dentistry, Gainesville, FL 32610, USA;
- Correspondence:
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14
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Ou NC, Preradovic K, Ferenczy ET, Sparrow CB, Germaine IM, Jurca T, Craciun V, McElwee-White L. Synthesis and Evaluation of Molybdenum Imido-Thiolato Complexes for the Aerosol-Assisted Chemical Vapor Deposition of Nitrogen-Doped Molybdenum Disulfide. Organometallics 2020. [DOI: 10.1021/acs.organomet.9b00705] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Nathan C. Ou
- Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, United States
| | - Konstantin Preradovic
- Department of Chemistry and the Renewable Energy and Chemical Transformations Cluster, University of Central Florida, Orlando, Florida 32816-2366, United States
| | - Erik T. Ferenczy
- Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, United States
| | - Courtney B. Sparrow
- Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, United States
| | - Ian M. Germaine
- Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, United States
| | - Titel Jurca
- Department of Chemistry and the Renewable Energy and Chemical Transformations Cluster, University of Central Florida, Orlando, Florida 32816-2366, United States
| | - Valentin Craciun
- National Institute for Laser, Plasma, and Radiation Physics, Bucharest-Magurele, Romania
- Extreme Light Infrastructure for Nuclear Physics, Bucharest-Magurele, Romania
| | - Lisa McElwee-White
- Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, United States
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15
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Carey PH, Ren F, Jia Z, Batich CD, Camargo SEA, Clark AE, Craciun V, Neal DW, Esquivel-Upshaw JF. Antibacterial Properties of Charged TiN Surfaces for Dental Implant Application. ChemistrySelect 2019; 4:9185-9189. [PMID: 32149184 PMCID: PMC7059626 DOI: 10.1002/slct.201901001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 08/01/2019] [Indexed: 02/03/2023]
Abstract
The formation and characterization of positively surface charged TiN surfaces were investigated for improving dental implant survival. Surface nitrogen atoms of a traditional TiN implant were converted to a positive charge by a quaternization reaction which greatly increased the antibacterial efficiency. Ti, TiN, and quaternized TiN samples were incubated with human patient subgingival bacteria for 4 hours at 37°C in an anaerobic environment with an approximate 40% reduction in counts on the quaternized surface over traditional Ti and TiN. The samples were challenged with Streptococcus Mutans and fluorescent imaging confirmed significant reduction in the quaternized TiN over the traditional Ti and TiN. Contact angle measurement and X-Ray Photoelectron Spectroscopy (XPS) were utilized to confirm the surface chemistry changes. The XPS results found the charged quaternized nitrogen peak at 399.75 eV that is unique to the quaternized sample.
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Affiliation(s)
- Patrick H Carey
- Department of Chemical Engineering, University of Florida, Gainesville, FL
| | - Fan Ren
- Department of Chemical Engineering, University of Florida, Gainesville, FL
| | - Ziqi Jia
- Department of Materials Science and Engineering, University of Florida, Gainesville, FL
| | - Christopher D Batich
- Department of Materials Science and Engineering, University of Florida, Gainesville, FL
| | - Samira E A Camargo
- Restorative Dental Sciences, Division of Prosthodontics University of Florida, Gainesville
| | - Arthur E Clark
- Restorative Dental Sciences, Division of Prosthodontics University of Florida, Gainesville
| | - Valentin Craciun
- National Institute for Lasers, Plasma and Radiation Physics, Magurele-Ilfov, Romania, and DENTIX MILLENNIUM SRL, Sabareni-Ilfov, Romania
| | - Daniel W Neal
- Department of Neurosurgery, University of Florida, Gainesville, FL
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16
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Ou NC, Bock DC, Su X, Craciun D, Craciun V, McElwee-White L. Growth of WO x from Tungsten(VI) Oxo-Fluoroalkoxide Complexes with Partially Fluorinated β-Diketonate/β-Ketoesterate Ligands: Comparison of Chemical Vapor Deposition to Aerosol-Assisted CVD. ACS Appl Mater Interfaces 2019; 11:28180-28188. [PMID: 31314491 DOI: 10.1021/acsami.9b08830] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Tungsten(VI) oxo complexes of the type WO(OR)3L [R = C(CH3)2CF3, C(CF3)2CH3, CH(CF3)2, L = hexafluoroacetylacetonate (hfac), ethyl trifluoroacetoacetonate (etfac), acetylacetonate (acac)] bearing partially fluorinated alkoxide and/or chelating ligands were synthesized. Thermal decomposition behavior and mass spectrometry (MS) fragmentation patterns of selected examples were studied. The thermolysis products of WO(OC(CF3)2CH3)3(hfac) were characterized by nuclear magnetic resonance and gas chromatography-MS. Studies of the sublimation behavior of the complexes demonstrated that their volatility depends on the degree of fluorination. Comparative studies of the deposition of tungsten oxide by chemical vapor deposition (CVD) and aerosol-assisted CVD were carried out using WO(OC(CF3)2CH3)3(hfac) as a single-source precursor. WOx materials were successfully deposited by both deposition methods, but the deposits differed in morphology, structure, and crystallinity.
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Affiliation(s)
- Nathan C Ou
- Department of Chemistry , University of Florida , Gainesville , Florida 32611-7299 , United States
| | - Duane C Bock
- Department of Chemistry , University of Florida , Gainesville , Florida 32611-7299 , United States
| | - Xiaoming Su
- Department of Chemistry , University of Florida , Gainesville , Florida 32611-7299 , United States
| | - Doina Craciun
- National Institute for Laser, Plasma, and Radiation Physics , Magurele RO-077125 , Bucharest , Romania
| | - Valentin Craciun
- National Institute for Laser, Plasma, and Radiation Physics , Magurele RO-077125 , Bucharest , Romania
- Extreme Light Infrastructure for Nuclear Physics , Magurele 700032 , Bucharest , Romania
| | - Lisa McElwee-White
- Department of Chemistry , University of Florida , Gainesville , Florida 32611-7299 , United States
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Prepelita P, Stavarache I, Craciun D, Garoi F, Negrila C, Sbarcea BG, Craciun V. Rapid thermal annealing for high-quality ITO thin films deposited by radio-frequency magnetron sputtering. Beilstein J Nanotechnol 2019; 10:1511-1522. [PMID: 31431863 PMCID: PMC6664415 DOI: 10.3762/bjnano.10.149] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 07/05/2019] [Indexed: 05/28/2023]
Abstract
In this work, rapid thermal annealing (RTA) was applied to indium tin oxide (ITO) films in ambient atmosphere, resulting in significant improvements of the quality of the ITO films that are commonly used as conductive transparent electrodes for photovoltaic structures. Starting from a single sintered target (purity 99.95%), ITO thin films of predefined thickness (230 nm, 300 nm and 370 nm) were deposited at room temperature by radio-frequency magnetron sputtering (rfMS). After deposition, the films were subjected to a RTA process at 575 °C (heating rate 20 °C/s), maintained at this temperature for 10 minutes, then cooled down to room temperature at a rate of 20 °C/s. The film structure was modified by changing the deposition thickness or the RTA process. X-ray diffraction investigations revealed a cubic nanocrystalline structure for the as-deposited ITO films. After RTA, polycrystalline compounds with a textured (222) plane were observed. X-ray photon spectroscopy was used to confirm the beneficial effect of the RTA treatment on the ITO chemical composition. Using a Tauc plot, values of the optical band gap ranging from 3.17 to 3.67 eV were estimated. These values depend on the heat treatment and the thickness of the sample. Highly conductive indium tin oxide thin films (ρ = 7.4 × 10-5 Ω cm) were obtained after RTA treatment in an open atmosphere. Such films could be used to manufacture transparent contact electrodes for solar cells.
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Affiliation(s)
- Petronela Prepelita
- National Institute for Laser, Plasma and Radiation Physics, P.O. Box MG-36, Magurele 077125, Ilfov, Romania
| | - Ionel Stavarache
- National Institute of Materials Physics, 405A Atomistilor Street, P.O. Box MG-7, Magurele 077125, Ilfov, Romania
| | - Doina Craciun
- National Institute for Laser, Plasma and Radiation Physics, P.O. Box MG-36, Magurele 077125, Ilfov, Romania
| | - Florin Garoi
- National Institute for Laser, Plasma and Radiation Physics, P.O. Box MG-36, Magurele 077125, Ilfov, Romania
| | - Catalin Negrila
- National Institute of Materials Physics, 405A Atomistilor Street, P.O. Box MG-7, Magurele 077125, Ilfov, Romania
| | | | - Valentin Craciun
- National Institute for Laser, Plasma and Radiation Physics, P.O. Box MG-36, Magurele 077125, Ilfov, Romania
- Dentix MILLENNIUM SRL, Sabareni-Ilfov, Romania
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18
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Pathak TK, Kroon RE, Craciun V, Popa M, Chifiriuc MC, Swart HC. Influence of Ag, Au and Pd noble metals doping on structural, optical and antimicrobial properties of zinc oxide and titanium dioxide nanomaterials. Heliyon 2019; 5:e01333. [PMID: 30923765 PMCID: PMC6424016 DOI: 10.1016/j.heliyon.2019.e01333] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 12/08/2018] [Accepted: 03/06/2019] [Indexed: 10/27/2022] Open
Abstract
Oxide materials (ZnO, TiO2) doped with noble metals were synthesized using the combustion technique. The results of the addition of Ag, Au, and Pd up to a concentration of 2 mol% on the structural, optical, morphological and antimicrobial properties was considered. X-ray diffraction experiments revealed that the crystal structure of the host materials remained unaltered despite doping with noble metals. From the scanning electron microscopy results, it was evident that the doped nanoparticles aggregated in clusters of different sizes in the host matrix. The plasmonic effect was also observed in the absorbance spectra of the different doped materials. The obtained materials have shown promising antimicrobial features. All ZnO materials exhibited a high antimicrobial activity, with very low minimum inhibitory concentration values, against the planktonic growth of all tested Gram-positive and Gram-negative bacterial strains. All doped materials exhibited very good anti-biofilm activity, the lowest minimal biofilm eradication concentration values being registered for ZnO doped with Au and Pd toward Escherichia coli and for ZnO doped with Ag against Candida albicans. These results indicate the potential that these materials have for antimicrobial applications in the fields of biomedicine and environmental protection.
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Affiliation(s)
- Trilok K Pathak
- Department of Physics, Teerthanker Mahaveer University, Moradabad, India.,Department of Physics, University of the Free State, Bloemfontein, South Africa
| | - R E Kroon
- Department of Physics, University of the Free State, Bloemfontein, South Africa
| | - Valentin Craciun
- National Institute for Laser, Bucharest, Magurele, Romania.,Dentix MileniumSRL, Sabareni, Ilfov, Romania
| | - Marcela Popa
- Microbiology Immunology Department, Faculty of Biology, The Research Institute of the University of Bucharest (ICUB), University of Bucharest, 77206, Bucharest, Romania
| | - M C Chifiriuc
- Microbiology Immunology Department, Faculty of Biology, The Research Institute of the University of Bucharest (ICUB), University of Bucharest, 77206, Bucharest, Romania
| | - H C Swart
- Department of Physics, University of the Free State, Bloemfontein, South Africa
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19
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Hermann J, Axente E, Pelascini F, Craciun V. Analysis of Multi-elemental Thin Films via Calibration-Free Laser-Induced Breakdown Spectroscopy. Anal Chem 2019; 91:2544-2550. [DOI: 10.1021/acs.analchem.8b05780] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jörg Hermann
- Aix-Marseille University, CNRS, LP3, 13009 Marseille, France
| | - Emanuel Axente
- National Institute for Lasers, Plasma and Radiation Physics, 77125 Mǎgurele, Romania
| | | | - Valentin Craciun
- National Institute for Lasers, Plasma and Radiation Physics, 77125 Mǎgurele, Romania
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20
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Hermann J, Grojo D, Axente E, Gerhard C, Burger M, Craciun V. Ideal radiation source for plasma spectroscopy generated by laser ablation. Phys Rev E 2017; 96:053210. [PMID: 29347637 DOI: 10.1103/physreve.96.053210] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Indexed: 11/07/2022]
Abstract
Laboratory plasmas inherently exhibit temperature and density gradients leading to complex investigations. We show that plasmas generated by laser ablation can constitute a robust exception to this. Supported by emission features not observed with other sources, we achieve plasmas of various compositions which are both uniform and in local thermodynamic equilibrium. These properties characterize an ideal radiation source opening multiple perspectives in plasma spectroscopy. The finding also constitutes a breakthrough in the analytical field as fast analyses of complex materials become possible.
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Affiliation(s)
- Jörg Hermann
- Aix-Marseille University, CNRS, LP3, 13009 Marseille, France
| | - David Grojo
- Aix-Marseille University, CNRS, LP3, 13009 Marseille, France
| | - Emanuel Axente
- National Institute for Lasers, Plasma and Radiation Physics, 077125 Măgurele, Romania
| | - Christoph Gerhard
- Technical University of Applied Sciences Wildau, 15745 Wildau, Germany
| | - Miloš Burger
- University of Belgrade, Faculty of Physics, 11000 Belgrade, Serbia
| | - Valentin Craciun
- National Institute for Lasers, Plasma and Radiation Physics, 077125 Măgurele, Romania
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21
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Martin C, Miller KH, Makino H, Craciun D, Simeone D, Craciun V. Optical properties of Ar ions irradiated nanocrystalline ZrC and ZrN thin films. J Nucl Mater 2017; Volume 488:16-21. [PMID: 32020950 PMCID: PMC6999656 DOI: 10.1016/j.jnucmat.2017.02.041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Thin nanocrystalline ZrC and ZrN films (<400 nm), grown on (100) Si substrates at a substrate temperature of 500 °C by the pulsed laser deposition (PLD) technique, were irradiated by 800 keV Ar ion irradiation with fluences from 1 × 1014 at/cm2 up to 2 × 1015 at/cm2. Optical reflectance data, acquired from as-deposited and irradiated films, in the range of 500 - 50000 cm-1 (0.06 - 6 eV), was used to assess the effect of irradiation on the optical and electronic properties. Both in ZrC and ZrN films we observed that irradiation affects the optical properties of the films mostly at low frequencies, which is dominated by the free carriers response. In both materials, we found a significant reduction in the free carriers scattering rate, i.e. possible increase in mobility, at higher irradiation flux. This is consistent with our previous findings that irradiation affects the crystallite size and the micro-strain, but it does not induce major structural changes.
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Affiliation(s)
- C. Martin
- Ramapo College of New Jersey, NJ, USA
| | - K. H. Miller
- NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
| | - H. Makino
- Research Institute, Kochi University of Technology, Kami, Kochi, 782-8502, Japan
| | - D. Craciun
- National Institute for Laser, Plasma, and Radiation Physics, Bucharest-Magurele, Romania
| | - D. Simeone
- CEA/DEN/DANS/DM2S/SERMA/LEPP-LRC CARMEN CEN Saclay France & CNRS/ SPMS UMR8785 LRC CARMEN, Ecole Centrale de Paris, F92292, Chatenay Malabry
| | - V. Craciun
- National Institute for Laser, Plasma, and Radiation Physics, Bucharest-Magurele, Romania
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22
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Popescu AC, Stan GE, Duta L, Nita C, Popescu C, Surdu VA, Husanu MA, Bita B, Ghisleni R, Himcinschi C, Craciun V. The Role of Ambient Gas and Pressure on the Structuring of Hard Diamond-Like Carbon Films Synthesized by Pulsed Laser Deposition. Materials 2015. [PMCID: PMC5455729 DOI: 10.3390/ma8063284] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Hard carbon thin films were synthesized on Si (100) and quartz substrates by the Pulsed Laser Deposition (PLD) technique in vacuum or methane ambient to study their suitability for applications requiring high mechanical resistance. The deposited films’ surface morphology was investigated by scanning electron microscopy, crystalline status by X-ray diffraction, packing and density by X-ray reflectivity, chemical bonding by Raman and X-ray photoelectron spectroscopy, adherence by “pull-out” measurements and mechanical properties by nanoindentation tests. Films synthesized in vacuum were a-C DLC type, while films synthesized in methane were categorized as a-C:H. The majority of PLD films consisted of two layers: one low density layer towards the surface and a higher density layer in contact with the substrate. The deposition gas pressure played a crucial role on films thickness, component layers thickness ratio, structure and mechanical properties. The films were smooth, amorphous and composed of a mixture of sp3-sp2 carbon, with sp3 content ranging between 50% and 90%. The thickness and density of the two constituent layers of a film directly determined its mechanical properties.
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Affiliation(s)
- Andrei C. Popescu
- National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, Magurele RO-077125, Romania; E-Mails: (L.D.); (C.N.); (C.P.); (V.C.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel./Fax: +40-21-457-4491
| | - George E. Stan
- National Institute of Materials Physics, 105bis Atomistilor Street, Magurele RO-077125, Romania; E-Mails: (G.E.S.); (M.-A.H.)
| | - Liviu Duta
- National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, Magurele RO-077125, Romania; E-Mails: (L.D.); (C.N.); (C.P.); (V.C.)
| | - Cristina Nita
- National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, Magurele RO-077125, Romania; E-Mails: (L.D.); (C.N.); (C.P.); (V.C.)
| | - Camelia Popescu
- National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, Magurele RO-077125, Romania; E-Mails: (L.D.); (C.N.); (C.P.); (V.C.)
| | - Vasile-Adrian Surdu
- Faculty of Applied Chemistry and Materials Science, University Politehnica from Bucharest, 1–7 Gh. Polizu Street, Bucharest RO-011061, Romania; E-Mail:
| | - Marius-Adrian Husanu
- National Institute of Materials Physics, 105bis Atomistilor Street, Magurele RO-077125, Romania; E-Mails: (G.E.S.); (M.-A.H.)
| | - Bogdan Bita
- National Institute for Research and Development in Microtechnologies, 126A Erou Iancu Nicolae Street, Voluntari RO-077190, Romania; E-Mail:
| | - Rudy Ghisleni
- Laboratory of Advanced Materials Processing, EMPA-Swiss Federal Laboratories for Materials Science and Technology, 39 Feuerwerkerstrasse, Thun CH-3602, Switzerland; E-Mail:
| | - Cameliu Himcinschi
- Institute of Theoretical Physics, TU Bergakademie Freiberg, Freiberg D-09596, Germany; E-Mail:
| | - Valentin Craciun
- National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, Magurele RO-077125, Romania; E-Mails: (L.D.); (C.N.); (C.P.); (V.C.)
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23
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Kim JK, Kim KW, Douglas EA, Gila BP, Craciun V, Lambers ES, Norton DP, Ren F, Pearton SJ, Cho H. Band offsets in YSZ/InGaZnO4 heterostructure system. J Nanosci Nanotechnol 2014; 14:3925-3927. [PMID: 24734665 DOI: 10.1166/jnn.2014.7939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The energy discontinuity in the valence band (deltaE(v)) of Y2O3-stabilized ZrO2 (YSZ)/InGaZnO4 (IGZO) heterostructures was obtained from X-ray photoelectron spectroscopy (XPS) measurements. The YSZ exhibited a bandgap of 4.4 eV from absorption measurements. A value of deltaE(v) = 0.57 +/- 0.12 eV was obtained by using Ga 2P3/2, Zn 2p3/2 and In 3d5/2 energy levels as references. This implies a conduction band offset (deltaE(c)) of 0.63 eV in YSZ/InGaZnO4 heterostructures and a nested interface band alignment.
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24
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Amirhaghi S, Beech F, Craciun V, Sajjadi A, Vickers M, Tarling S, Barnes P, Andboydi W. Growth of Cerium Oxide Buffer Layers and Superconducting thin films on Silicon. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-275-501] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTFilms of CeO2 have been grown on Si and glass substrates using the laser ablation deposition technique. X-ray diffraction measurements for the films deposited on glass indicated that they are the same as films grown on Si covered with the native oxide. This evidence supports a picture in which chemical rather than crystal-lographic effects constrain the film growth. The crystal quality for films grown on Si was shown to improve with increasing film thickness away from the amorphous layer. Low cooling rates as well as reduced film thickness were effective in avoiding the formation of micro-cracks. The surface morphology was shown to be dependent on the laser wave-length as well as the oxygen partial pressure. Thin films of YBa2Cu3O7δ could easily be grown on CeO2/Si showing c-axis orientation, whereas the growth of BiSrCaCuO (2212) on CeO2/Si resulted in the two films mixing with each other.
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Yu D, Trad T, McLeskey JT, Craciun V, Taylor CR. ZnO Nanowires Synthesized by Vapor Phase Transport Deposition on Transparent Oxide Substrates. Nanoscale Res Lett 2010; 5:1333-9. [PMID: 20676196 PMCID: PMC2897031 DOI: 10.1007/s11671-010-9649-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Accepted: 05/17/2010] [Indexed: 05/14/2023]
Abstract
Zinc oxide nanowires have been synthesized without using metal catalyst seed layers on fluorine-doped tin oxide (FTO) substrates by a modified vapor phase transport deposition process using a double-tube reactor. The unique reactor configuration creates a Zn-rich vapor environment that facilitates formation and growth of zinc oxide nanoparticles and wires (20-80 nm in diameter, up to 6 μm in length, density <40 nm apart) at substrate temperatures down to 300°C. Electron microscopy and other characterization techniques show nanowires with distinct morphologies when grown under different conditions. The effect of reaction parameters including reaction time, temperature, and carrier gas flow rate on the size, morphology, crystalline structure, and density of ZnO nanowires has been investigated. The nanowires grown by this method have a diameter, length, and density appropriate for use in fabricating hybrid polymer/metal oxide nanostructure solar cells. For example, it is preferable to have nanowires no more than 40 nm apart to minimize exciton recombination in polymer solar cells.
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Affiliation(s)
- Dongshan Yu
- Department of Mechanical Engineering, Virginia Commonwealth University, 401 W. Main Street, P.O. Box 843015, Richmond, VA, 23284-3015, USA
| | - Tarek Trad
- Department of Chemistry and Environmental Science, University of Texas at Brownsville, 80 Fort Brown, Brownsville, TX, 78520, USA
| | - James T McLeskey
- Department of Mechanical Engineering, Virginia Commonwealth University, 401 W. Main Street, P.O. Box 843015, Richmond, VA, 23284-3015, USA
| | - Valentin Craciun
- Department of Materials Science and Engineering, University of Florida, 320 MAE, Gainesville, FL, 32611, USA
| | - Curtis R Taylor
- Department of Mechanical and Aerospace Engineering, University of Florida, 320 MAE, Gainesville, FL, 32611, USA
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Coowanitwong I, Arya V, Patel G, Kim WS, Craciun V, Rocca JR, Singh R, Hochhaus G. Laser-ablated nanofunctional polymers for the formulation of slow-release powders for dry powder inhalers: physicochemical characterization and slow-release characteristics. J Pharm Pharmacol 2008; 59:1473-84. [PMID: 17976257 DOI: 10.1211/jpp.59.11.0003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Recently, dry powder inhalation (DPI) powders coated with nanometre-thin layers of biodegradable polymers, prepared using pulse laser deposition (PLD), have been evaluated as a slow-release formulation for DPI use, with the goal of improving pulmonary selectivity. This paper describes evaluation of the chemical stability of one potential polymer, poly lactic acid (PLA), during the ablation process, the resulting respirable properties and potential cytotoxicity of coated glucocorticoid powders, and the resulting sustained-release characteristics of PLA-coated glucocorticoids creating using PLD. Triamcinolone acetonide (TA) and budesonide (BUD) were used as two model glucocorticoids to determine pulmonary targeting (PT) in-vivo. The chemical stability of PLA was determined at various laser energy densities. The respirable fraction and the cytotoxicity of the micronized particles of TA and BUD, coated using optimum laser energy density, were determined. In-vitro dissolution profiles were generated for the coated/uncoated formulations and an ex-vivo receptor binding assay was used to determine PT in rats. Increasing laser energy density led to decreases in molecular weight and film density, and increases in degradation products, roughness and thickness of the film. The mean dissolution time of coated formulations of BUD was longer (4 h) than with the less lipophilic TA (2 h). This correlated well with a more pronounced pulmonary selectivity observed for coated BUD ex-vivo. Stability and the physical properties of the film correlated with the laser energy density. We observed a direct relationship between the dissolution rate of the uncoated and coated formulation and the degree of PT; however, physiochemical properties of the drug (e.g. lipophilicity) may also contribute to the improved PT.
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Affiliation(s)
- Intira Coowanitwong
- Department of Pharmaceutics, College of Pharmacy, University of Florida, Gainesville, FL 32610, USA
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Abstract
The solvent-induced film structure of poly(n-vinyl carbazole) (PVK) thin films on indium tin oxide (ITO)-coated glass was examined. PVK thin films were prepared via spin-coating using five different solvents. We investigated the relationship between the solvent characteristics and film properties, including surface roughness and structure, film thickness, and density. The spin-coated polymer thin films are not in thermodynamic equilibrium; rather, the film properties are affected by the dynamics of the spin-coating process. We found that water present in tetrahydrofuran (THF) induces dewetting of PVK films during the spin-coating process. Solvents with a high evaporation rate lead to high surface roughness due to Marangoni convection. The results show that the surface roughness and structure of the films are dominated by the dynamics of the film formation process, rather than thermodynamic interactions between the polymer and solvents.
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Affiliation(s)
- Shyh-Chyang Luo
- Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611, USA
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28
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Nelea V, Pelletier H, Iliescu M, Werckmann J, Craciun V, Mihailescu IN, Ristoscu C, Ghica C. Calcium phosphate thin film processing by pulsed laser deposition and in situ assisted ultraviolet pulsed laser deposition. J Mater Sci Mater Med 2002; 13:1167-1173. [PMID: 15348661 DOI: 10.1023/a:1021150207350] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Calcium orthophosphates (CaP) and hydroxyapatite (HA) were intensively studied in order to design and develop a new generation of bioactive and osteoconductive bone prostheses. The main drawback now in the CaP and HA thin films processing persists in their poor mechanical characteristics, namely hardness, tensile and cohesive strength, and adherence to the metallic substrate. We report here a critical comparison between the microstructure and mechanical properties of HA and CaP thin films grown by two methods. The films were grown by KrF* pulsed laser deposition (PLD) or KrF* pulsed laser deposition assisted by in situ ultraviolet radiation emitted by a low pressure Hg lamp (UV-assisted PLD). The PLD films were deposited at room temperature, in vacuum on Ti-5Al-2.5Fe alloy substrate previously coated with a TiN buffer layer. After deposition the films were annealed in ambient air at 500-600 degrees C. The UV-assisted PLD films were grown in (10(-2)-10(-1) Pa) oxygen directly on Ti-5Al-2.5Fe substrates heated at 500-600 degrees C. The films grown by classical PLD are crystalline and stoichiometric. The films grown by UV-assisted PLD were crystalline and exhibit the best mechanical characteristics with values of hardness and Young modulus of 6-7 and 150-170 GPa, respectively, which are unusually high for the calcium phosphate ceramics. To the difference of PLD films, in the case of UV-assisted PLD, the GIXRD spectra show the decomposition of HA in Ca(2)P(2)O(7), Ca(2)P(2)O(9) and CaO. The UV lamp radiation enhanced the gas reactivity and atoms mobility during processing, increasing the tensile strength of the film, while the HA structure was destroyed.
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Affiliation(s)
- V Nelea
- Laboratoire d'Ingénierie de Surface, Ecole Nationale Supérieure des Arts et Industries, 24 Bld. de la Victoire, F-67084, Strasbourg, France.
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Craciun C, Ghircoiasiu M, Craciun V. Electron-microscopic studies on the effect of calcium pantothenate upon rat liver and locally irradiated epidermis. Acta Morphol Hung 1992; 40:231-48. [PMID: 1365767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 03/25/2023]
Abstract
Calcium pantothenate was administered to Wistar rats in a dose of 180 mg/day/rat for 42 days, in order to investigate its effect upon the ultrastructure of the epidermis locally irradiated with a dose of 600 rep and upon partly hepatectomized liver and locally irradiated epidermis, as compared to control. The resulting data have revealed that calcium pantothenate is metabolized without entailing ultrastructural changes. Both liver and epidermis appear to be protected by calcium pantothenate, which greatly diminishes or even cancels the display of irradiation-induced negative effects. The changes brought about by irradiation are throughly presented and the subcellular mechanisms providing the radioprotection of epidermis and liver are accurately defined.
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Affiliation(s)
- C Craciun
- Babes-Bolyai University, Dept. Biology, Cluj-Napoca, Romania
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Amirhaghi S, Craciun V, Beech F, Vickers M, Tarling S, Barnes P, Boyd IW. Pulsed Laser Deposition of High Quality ZnO Thin Films. ACTA ACUST UNITED AC 1992. [DOI: 10.1557/proc-285-489] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTThin films of ZnO have been grown on silicon and glass substrates by the pulsed laser deposition method. The effects of the oxygen partial pressure, substrate temperature and laser wavelength on the structural and optical properties of the films have been studied. The KrF excimer laser (at 248 nm) was found to produce better quality thin films than the frequency doubled Nd:YAG laser (532 nm). Layers produced at substrate temperatures as low as 300°C were c-axis oriented with a FWHM value for the 002 XRD reflection less than 0.2° and exhibited optical transmission higher than 80% in the visible region.
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