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Kostoglou N, Stock S, Solomi A, Holzapfel DM, Hinder S, Baker M, Constantinides G, Ryzhkov V, Maletaskic J, Matovic B, Schneider JM, Rebholz C, Mitterer C. The Roles of Impurities and Surface Area on Thermal Stability and Oxidation Resistance of BN Nanoplatelets. Nanomaterials (Basel) 2024; 14:601. [PMID: 38607135 PMCID: PMC11013371 DOI: 10.3390/nano14070601] [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: 02/21/2024] [Revised: 03/22/2024] [Accepted: 03/24/2024] [Indexed: 04/13/2024]
Abstract
This study considers the influence of purity and surface area on the thermal and oxidation properties of hexagonal boron nitride (h-BN) nanoplatelets, which represent crucial factors in high-temperature oxidizing environments. Three h-BN nanoplatelet-based materials, synthesized with different purity levels and surface areas (~3, ~56, and ~140 m2/g), were compared, including a commercial BN reference. All materials were systematically analyzed by various characterization techniques, including gas pycnometry, scanning electron microscopy, X-ray diffraction, Fourier-transform infrared radiation, X-ray photoelectron spectroscopy, gas sorption analysis, and thermal gravimetric analysis coupled with differential scanning calorimetry. Results indicated that the thermal stability and oxidation resistance of the synthesized materials were improved by up to ~13.5% (or by 120 °C) with an increase in purity. Furthermore, the reference material with its high purity and low surface area (~4 m2/g) showed superior performance, which was attributed to the minimized reactive sites for oxygen diffusion due to lower surface area availability and fewer possible defects, highlighting the critical roles of both sample purity and accessible surface area in h-BN thermo-oxidative stability. These findings highlight the importance of focusing on purity and surface area control in developing BN-based nanomaterials, offering a path to enhance their performance in extreme thermal and oxidative conditions.
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Affiliation(s)
- Nikolaos Kostoglou
- Department of Materials Science, Montanuniversität Leoben, 8700 Leoben, Austria; (A.S.); (C.R.); (C.M.)
| | - Sebastian Stock
- Department Physics, Mechanics and Electrical Engineering, Montanuniversität Leoben, 8700 Leoben, Austria;
| | - Angelos Solomi
- Department of Materials Science, Montanuniversität Leoben, 8700 Leoben, Austria; (A.S.); (C.R.); (C.M.)
- Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia 2109, Cyprus
| | - Damian M. Holzapfel
- Materials Chemistry, RWTH Aachen University, 52074 Aachen, Germany; (D.M.H.); (J.M.S.)
| | - Steven Hinder
- Department of Mechanical Engineering Sciences, University of Surrey, Guildford GU2 7XH, UK; (S.H.); (M.B.)
| | - Mark Baker
- Department of Mechanical Engineering Sciences, University of Surrey, Guildford GU2 7XH, UK; (S.H.); (M.B.)
| | - Georgios Constantinides
- Department of Mechanical Engineering and Materials Science and Engineering, Cyprus University of Technology, Lemesos 3036, Cyprus;
| | - Vladislav Ryzhkov
- Research School of High-Energy Physics, Tomsk Polytechnic University, 634050 Tomsk, Russia;
| | - Jelena Maletaskic
- Vinča Institute of Nuclear Sciences—National Institute of the Republic of Serbia, University of Belgrade, 11000 Belgrade, Serbia; (J.M.); (B.M.)
| | - Branko Matovic
- Vinča Institute of Nuclear Sciences—National Institute of the Republic of Serbia, University of Belgrade, 11000 Belgrade, Serbia; (J.M.); (B.M.)
| | - Jochen M. Schneider
- Materials Chemistry, RWTH Aachen University, 52074 Aachen, Germany; (D.M.H.); (J.M.S.)
| | - Claus Rebholz
- Department of Materials Science, Montanuniversität Leoben, 8700 Leoben, Austria; (A.S.); (C.R.); (C.M.)
- Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia 2109, Cyprus
| | - Christian Mitterer
- Department of Materials Science, Montanuniversität Leoben, 8700 Leoben, Austria; (A.S.); (C.R.); (C.M.)
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Knabl F, Kostoglou N, Terziyska V, Hinder S, Baker M, Bousser E, Rebholz C, Mitterer C. Short-Time Magnetron Sputtering for the Development of Carbon-Palladium Nanocomposites. Nanomaterials (Basel) 2024; 14:164. [PMID: 38251129 PMCID: PMC10818909 DOI: 10.3390/nano14020164] [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: 12/01/2023] [Revised: 01/01/2024] [Accepted: 01/09/2024] [Indexed: 01/23/2024]
Abstract
In recent nanomaterials research, combining nanoporous carbons with metallic nanoparticles, like palladium (Pd), has emerged as a focus due to their potential in energy, environmental and biomedical fields. This study presents a novel approach for synthesizing Pd-decorated carbons using magnetron sputter deposition. This method allows for the functionalization of nanoporous carbon surfaces with Pd nano-sized islands, creating metal-carbon nanocomposites through brief deposition times of up to 15 s. The present research utilized direct current magnetron sputtering to deposit Pd islands on a flexible activated carbon cloth substrate. The surface chemistry, microstructure, morphology and pore structure were analyzed using a variety of material characterization techniques, including X-ray photoelectron spectroscopy, X-ray diffraction, Raman spectroscopy, gas sorption analysis and scanning electron microscopy. The results showed Pd islands of varying sizes distributed across the cloth's carbon fibers, achieving high-purity surface modifications without the use of chemicals. The synthesis method preserves the nanoporous structure of the carbon cloth substrate while adding functional Pd islands, which could be potentially useful in emerging fields like hydrogen storage, fuel cells and biosensors. This approach demonstrates the possibility of creating high-quality metal-carbon composites using a simple, clean and economical method, expanding the possibilities for future nanomaterial-based applications.
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Affiliation(s)
- Florian Knabl
- Department of Materials Science, Montanuniversitӓt Leoben, 8700 Leoben, Austria; (V.T.); (C.R.); (C.M.)
| | - Nikolaos Kostoglou
- Department of Materials Science, Montanuniversitӓt Leoben, 8700 Leoben, Austria; (V.T.); (C.R.); (C.M.)
| | - Velislava Terziyska
- Department of Materials Science, Montanuniversitӓt Leoben, 8700 Leoben, Austria; (V.T.); (C.R.); (C.M.)
| | - Steven Hinder
- Department of Mechanical Engineering Sciences, University of Surrey, Guildford GU2 7XH, UK; (S.H.); (M.B.)
| | - Mark Baker
- Department of Mechanical Engineering Sciences, University of Surrey, Guildford GU2 7XH, UK; (S.H.); (M.B.)
| | - Etienne Bousser
- Centre for Characterization and Microscopy of Materials (CM)2, Polytechnique Montréal, Montréal, QC H3T 1J4, Canada;
| | - Claus Rebholz
- Department of Materials Science, Montanuniversitӓt Leoben, 8700 Leoben, Austria; (V.T.); (C.R.); (C.M.)
- Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia 1678, Cyprus
| | - Christian Mitterer
- Department of Materials Science, Montanuniversitӓt Leoben, 8700 Leoben, Austria; (V.T.); (C.R.); (C.M.)
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Zulfiqar U, Kostoglou N, Thomas AG, Rebholz C, Matthews A, Lewis DJ. Flexible nanoporous activated carbon for adsorption of organics from industrial effluents. Nanoscale 2021; 13:15311-15323. [PMID: 34492671 DOI: 10.1039/d1nr03242a] [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] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
This paper reports a study involving the formation of a self-assembled polymeric monolayer on the surface of a high surface area activated carbon to engineer its affinity towards organic contaminants. A nanoporous activated carbon cloth with a surface area of ∼1220 m2 g-1 and a pore volume of ∼0.42 cm3 g-1 was produced by chemical impregnation, carbonisation and high-temperature CO2 activation of a commercially available viscose rayon cloth. The subsequent modification with a silane polymer resulted in a nanoscale self-assembled monolayer that made it selective towards organic solvents (contact angle <10°) and repellant towards water (contact angle >145°). The adsorbent showed more than 95% efficiency in the separation of various types of oil/water mixtures under neutral, basic and acidic conditions. Benefiting from inherent nanoscale features, a robust hierarchical structure and a thermally stable monolayer (∼300 °C), this nanoporous adsorbent maintained high efficiency for more than 20 cycles and separated surfactant stabilised emulsion with >92% oil removal efficiency. The adsorbent was studied extensively with a series of advanced characterisation techniques to establish the formation mechanism and performance in emulsion separation. Findings from this work provide crucial insights towards large-scale implementation of surface engineered activated carbon-based materials for a wide range of industrial separation applications.
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Affiliation(s)
- Usama Zulfiqar
- Department of Materials, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
| | - Nikolaos Kostoglou
- Department of Materials Science, Montanuniversität Leoben, 8700 Leoben, Austria
| | - Andrew G Thomas
- Department of Materials, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
| | - Claus Rebholz
- Department of Materials, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
- Department of Mechanical and Manufacturing Engineering, University of Cyprus, 1678 Nicosia, Cyprus
| | - Allan Matthews
- Department of Materials, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
| | - David J Lewis
- Department of Materials, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
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Kostoglou N, Tampaxis C, Charalambopoulou G, Constantinides G, Ryzhkov V, Doumanidis C, Matovic B, Mitterer C, Rebholz C. Boron Nitride Nanotubes Versus Carbon Nanotubes: A Thermal Stability and Oxidation Behavior Study. Nanomaterials (Basel) 2020; 10:E2435. [PMID: 33291505 PMCID: PMC7762177 DOI: 10.3390/nano10122435] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [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: 10/16/2020] [Revised: 11/27/2020] [Accepted: 12/03/2020] [Indexed: 11/17/2022]
Abstract
Nanotubes made of boron nitride (BN) and carbon have attracted considerable attention within the literature due to their unique mechanical, electrical and thermal properties. In this work, BN and carbon nanotubes, exhibiting high purity (>99%) and similar surface areas (~200 m2/g), were systematically investigated for their thermal stability and oxidation behavior by combining thermal gravimetric analysis and differential scanning calorimetry methods at temperatures of up to ~1300 °C under a synthetic air flow environment. The BN nanotubes showed a good resistance to oxidation up to ~900 °C and fully transformed to boron oxide up to ~1100 °C, while the carbon nanotubes were stable up to ~450 °C and almost completely combusted up to ~800 °C. The different oxidation mechanisms are attributed to the different chemical nature of the two types of nanotubes.
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Affiliation(s)
- Nikolaos Kostoglou
- Department of Materials Science, Montanuniversität Leoben, 8700 Leoben, Austria; (C.M.); (C.R.)
| | - Christos Tampaxis
- National Center for Scientific Research Demokritos, 15341 Athens, Greece; (C.T.); (G.C.)
| | | | - Georgios Constantinides
- Department of Mechanical and Materials Science and Engineering, Cyprus University of Technology, 3036 Lemesos, Cyprus;
| | - Vladislav Ryzhkov
- Research School of High-Energy Physics, Tomsk Polytechnic University, 634050 Tomsk, Russia;
| | | | - Branko Matovic
- Vinča Institute of Nuclear Sciences, University of Belgrade, 11000 Belgrade, Serbia;
| | - Christian Mitterer
- Department of Materials Science, Montanuniversität Leoben, 8700 Leoben, Austria; (C.M.); (C.R.)
| | - Claus Rebholz
- Department of Materials Science, Montanuniversität Leoben, 8700 Leoben, Austria; (C.M.); (C.R.)
- Department of Mechanical and Manufacturing Engineering, University of Cyprus, 1678 Nicosia, Cyprus
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Doumanidis CC, Al Kaabi HA, Alzaabi AS, Gunduz IE, Rebholz C, Doumanidis CC. Brownian-like kinematics of ball milling for particulate structural modeling. POWDER TECHNOL 2016. [DOI: 10.1016/j.powtec.2016.07.033] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Abstract
Ball milling (BM) offers a flexible process for nanomanufacturing of reactive bimetallic multiscale particulates (nanoheaters) for self-heated microjoining engineering materials and biomedical tooling. This paper introduces a mechanics-based process model relating the chaotic dynamics of BM with the random fractal structures of the produced particulates, emphasizing its fundamental concepts, underlying assumptions, and computation methods. To represent Apollonian globular and lamellar structures, the simulation employs warped ellipsoidal (WE) primitives of elasto-plastic strain-hardening materials, with Maxwell–Boltzmann distributions of ball kinetics and thermal transformation of hysteretic plastic, frictional, and residual stored energetics. Interparticle collisions are modeled via modified Hertzian contact impact mechanics, with local plastic deformation yielding welded microjoints and resulting in cluster assembly into particulates. The model tracks the size and diversity of such particulate populations as the process evolves via sequential collision and integration events. The simulation was shown to run in real-time computation speeds on modest hardware, and match successfully the fractal dimension and contour shape of experimental ball-milled Al–Ni particulate micrographs. Thus, the model serves as a base for the design of a feedback control system for continuous BM.
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Affiliation(s)
| | - I. E. Gunduz
- School of Mechanical Engineering, Purdue University, West Lafayette, IL 47907 e-mail:
| | - Claus Rebholz
- Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia 1678, Cyprus e-mail:
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Stylianopoulos T, Kokonou M, Michael S, Tryfonos A, Rebholz C, Odysseos AD, Doumanidis C. Tensile mechanical properties and hydraulic permeabilities of electrospun cellulose acetate fiber meshes. J Biomed Mater Res B Appl Biomater 2012; 100:2222-30. [DOI: 10.1002/jbm.b.32791] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2012] [Revised: 06/27/2012] [Accepted: 07/11/2012] [Indexed: 11/07/2022]
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8
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Betelu S, Polychronopoulou K, Rebholz C, Ignatiadis I. Novel CeO2-based screen-printed potentiometric electrodes for pH monitoring. Talanta 2011; 87:126-35. [DOI: 10.1016/j.talanta.2011.09.051] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 09/23/2011] [Accepted: 09/27/2011] [Indexed: 10/17/2022]
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9
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Gravani S, Polychronopoulou K, Stolojan V, Cui Q, Gibson PN, Hinder SJ, Gu Z, Doumanidis CC, Baker MA, Rebholz C. Growth and characterization of ceria thin films and Ce-doped γ-Al2O3 nanowires using sol-gel techniques. Nanotechnology 2010; 21:465606. [PMID: 20975211 DOI: 10.1088/0957-4484/21/46/465606] [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] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
γ-Al(2)O(3) is a well known catalyst support. The addition of Ce to γ-Al(2)O(3) is known to beneficially retard the phase transformation of γ-Al(2)O(3) to α-Al(2)O(3) and stabilize the γ-pore structure. In this work, Ce-doped γ-Al(2)O(3) nanowires have been prepared by a novel method employing an anodic aluminium oxide (AAO) template in a 0.01 M cerium nitrate solution, assisted by urea hydrolysis. Calcination at 500 °C for 6 h resulted in the crystallization of the Ce-doped AlOOH gel to form Ce-doped γ-Al(2)O(3) nanowires. Ce(3+) ions within the nanowires were present at a concentration of < 1 at.%. On the template surface, a nanocrystalline CeO(2) thin film was deposited with a cubic fluorite structure and a crystallite size of 6-7 nm. Characterization of the nanowires and thin films was performed using scanning electron microscopy, transmission electron microscopy, electron energy loss spectroscopy, x-ray photoelectron spectroscopy and x-ray diffraction. The nanowire formation mechanism and urea hydrolysis kinetics are discussed in terms of the pH evolution during the reaction. The Ce-doped γ-Al(2)O(3) nanowires are likely to find useful applications in catalysis and this novel method can be exploited further for doping alumina nanowires with other rare earth elements.
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Affiliation(s)
- S Gravani
- Mechanical and Manufacturing Engineering Department, Engineering School, University of Cyprus, Nicosia, Cyprus
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10
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Singh DP, Polychronopoulou K, Rebholz C, Aouadi SM. Room temperature synthesis and high temperature frictional study of silver vanadate nanorods. Nanotechnology 2010; 21:325601. [PMID: 20639583 DOI: 10.1088/0957-4484/21/32/325601] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We report the room temperature (RT) synthesis of silver vanadate nanorods (consisting of mainly beta-AgV O(3)) by a simple wet chemical route and their frictional study at high temperatures (HT). The sudden mixing of ammonium vanadate with silver nitrate solution under constant magnetic stirring resulted in a pale yellow coloured precipitate. Structural/microstructural characterization of the precipitate through x-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed the high yield and homogeneous formation of silver vanadate nanorods. The length of the nanorods was 20-40 microm and the thickness 100-600 nm. The pH variation with respect to time was thoroughly studied to understand the formation mechanism of the silver vanadate nanorods. This synthesis process neither demands HT, surfactants nor long reaction time. The silver vanadate nanomaterial showed good lubrication behaviour at HT (700 degrees C) and the friction coefficient was between 0.2 and 0.3. HT-XRD revealed that AgV O(3) completely transformed into silver vanadium oxide (Ag(2)V(4)O(11)) and silver with an increase in temperature from RT to 700 degrees C.
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Affiliation(s)
- D P Singh
- Department of Physics, Southern Illinois University, Carbondale, IL 62901, USA.
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11
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Temin E, Harrington L, Mitchell P, Rebholz C, Dyer K, Doyle J, Hughes P, Moyer P. 364: Success Rates in Out-of-Hospital Intubation. Ann Emerg Med 2008. [DOI: 10.1016/j.annemergmed.2008.06.391] [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: 11/28/2022]
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12
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Kokonou M, Rebholz C, Giannakopoulos KP, Doumanidis CC. Fabrication of nanorods by metal evaporation inside the pores of ultra-thin porous alumina templates. Nanotechnology 2007; 18:495604. [PMID: 20442478 DOI: 10.1088/0957-4484/18/49/495604] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Porous alumina has attracted a great deal of attention as a template material for the growth of nanowires and nanodots. Typically, the pores have a high aspect ratio, which forbid the use of evaporation techniques for filling them, due to a pore closure effect. For this reason electrochemical methods are mainly used. However, there are materials, such as Al, which are very difficult to deposit electrochemically. In this work, the fabrication of Al nanorods by electron gun evaporation into low aspect-ratio pores of ultra-thin porous alumina templates is described. The thicknesses of the templates are in the range from 50 to 70 nm, while their pores have diameters from 20 to 40 nm, i.e. their diameter:height aspect ratios are very low, from 1:1.5 to 1:3. These properties make it possible to completely fill the pores with evaporation techniques. This method can be generalized to any target and substrate material.
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Affiliation(s)
- M Kokonou
- Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia CY-1678, Cyprus.
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Anderson L, Rebholz C, Feldman J, Mitchell P, Curcio T, Kahn J. Variables Affecting Illness and Injury Among Long-distance Hikers. Acad Emerg Med 2007. [DOI: 10.1197/j.aem.2007.03.883] [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: 11/10/2022]
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14
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Chawla N, Feldman J, Moyer P, Dyer S, Manger J, Mitchell P, Rebholz C, Barnewolt B, Beshansky J, Brown D, Ho K, Jacobs A, Kimmelstiel C, Pearlmutter M, Rosenfield K, Ruthazer R, Shah PB, Selker H. Inter-observer Agreement about Out-of-hospital Notification of Acute ST Segment Elevation Myocardial Infarction. Acad Emerg Med 2007. [DOI: 10.1197/j.aem.2007.03.755] [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: 11/10/2022]
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Monclus MA, Baker MA, Rebholz C, Stolojan V, Gibson PN, Leyland A, Matthews A. Nanostructural studies of PVD TiAlB coatings. SURF INTERFACE ANAL 2006. [DOI: 10.1002/sia.2160] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Rebholz C, Bleicher W, Epple E. Eine ,Trendlupe' für die Registrierung von Vitalparameterverläufen. BIOMED ENG-BIOMED TE 1985. [DOI: 10.1515/bmte.1985.30.s1.165] [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: 11/15/2022]
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