catalin ducu | University of Pitesti (original) (raw)

Books by catalin ducu

Papers by catalin ducu

Proceedings "New Challenges in Heat Treatment and Surface Engineering" (ISBN: 978-953-96459-9-9) ; Editors: Smoljan, Božo and Matijević Božidar ; Publisher: Croatian Society for Heat Treatment and Surface Engineering, Zagreb, 2009, pages: 215-220, 2009

Current Trends in Natural Sciences, 2020

In recent years, more and more studies have highlighted the potential of fruits of Aronia melanoc... more In recent years, more and more studies have highlighted the potential of fruits of Aronia melanocarpa (Michx.) Elliott for the pharmaceutical and cosmetic industry, due to the high content of polyphenols and anthocyanins. Currently, the use of agricultural production of Aronia melanocarpa is mainly done through the use of fruit juice or powders in the food industry. In the present study we set out to achieve a superior route of fruit valorization by obtaining extracts for the pharmaceutical and cosmetics industry. For ultrasound-assisted extraction, Aronia melanocarpa fruits were preprocessed (drying, grinding, sieving) and then subjected to ultrasonic-assisted solvent extraction. The study carried out in this phase of the experiment followed the influence of the concentration of the solvent (water/ethanol ratio) on the anthocyanin content and the chromatographic profile of the extract. The chromatographic profile was obtained using the HPTLC method. The analysis material was represented by 3 extracts obtained under various experimental conditions, from the species Aronia melanocarpa (Michx.) Elliot fruits. The best HPTLC chromatographic imprint was shown for Aronia fruit extracts prepared in 3:1 water-ethanol mixture, at amplitude of 40%. In the other experimental variants the anthocyanin content was low.

IOP Conference Series: Materials Science and Engineering, 2019

Rene 41, super alloy nickel base with aging hardening, presents an exceptional strength at high t... more Rene 41, super alloy nickel base with aging hardening, presents an exceptional strength at high temperatures, find used at temperatures above 871°C. After aging, the microstructure of the alloy is made up of solid solution and precipitates and the mechanical properties show a significant variation with the aging temperature. The researches presented in this paper aims to determine the influence of thermal shocks at 1000 ° C on the alloy microstructure and the hardness. The heat shocks were applied in the surface, with the aid of solar energy, in 3 and 6 cycles of 30s. Samples were characterized, in surface and in section, by hardness measurements, scanning electron microscopy and EDX. The variations in the hardness characteristics were correlated with the structural transformations induced by the thermal shocks applied to the surface.

International Journal of Mechanical Sciences, 2019

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service... more This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Highlights  analytical solution for the estimate of the mean crushing force is proposed for structures with polygonal and star shaped crosssection;  literature available data were investigated for the validation of proposed model;  nondimensional analysis of the mean crushing force was performed for the evaluation of the results predicted by the proposed analytical solution;  proposed analytical solution was compared with existing, specific analytical solutions.

Applied Surface Science, 2006

Nanostructures formed by Au nanoparticles on ZnO thin film surface are of interest for applicatio... more Nanostructures formed by Au nanoparticles on ZnO thin film surface are of interest for applications which include medical implants, gassensors, and catalytic systems. A frequency tripled Nd:YAG laser (l = 355 nm, t FWHM $ 10 ns) was used for the successive irradiation of the Zn and Au targets. The ZnO films were synthesized in 20 Pa oxygen pressure while the subsequent Au coverage was grown in vacuum. The obtained structures surface morphology, crystalline quality, and chemical composition depth profile were investigated by acoustic (dynamic) mode atomic force microscopy, X-ray diffraction, and wavelength dispersive X-ray spectroscopy. The surface is characterized by a granular morphology, with average grain diameters of a few tens of nanometers. The surface roughness decreases with the increase of the number of laser pulses applied for the irradiation of the Au target. The Au coverage reveals a predominant (1 1 1) texture, whereas the underlying ZnO films are c-axis oriented. A linear dependence was established between the thickness of the Au coverage and the number of laser pulses applied for the irradiation of the Au target.

Journal of Science and Arts

In an attempt to obtain as much data as possible about the fragmentary sword discovered in 2017 i... more In an attempt to obtain as much data as possible about the fragmentary sword discovered in 2017 in one of the most important Dacian sites (Ocnita, Vâlcea County), but also about the way in which the environment in which it was preserved for approximatively 2,000 years has influenced its conservation status, the methods of characterization applied aim to obtain results concerning, on the one hand, the composition of the material from which the weapon was made, and as far as possible the technique used by the blacksmith craftsmen, and on the other hand, the composition of the soil in which the weapon was deposited to see the way the soil influenced the conservation state in which the weapon was found. Several analytical techniques, such as optical macroscopy (OM), X-ray fluorescence spectrometry (XRF), X-ray CT scanning, X-ray diffraction (XRD), scanning electron microscopy with energy dispersive spectroscopy (SEM) were used in order to investigate the corrosion processes that aroused...

2021 13th International Conference on Electronics, Computers and Artificial Intelligence (ECAI), 2021

Recently, superparamagnetic nanomaterials have paying attention great interest for to their catal... more Recently, superparamagnetic nanomaterials have paying attention great interest for to their catalytic properties and their applications. The present paper aims to make a description from the point of view of morphological, microstructural, and chemical elemental analysis of iron oxide powder, obtained by hydrolytic synthesis, using iron (III) FeC13 chloride as precursor and sodium hydroxide solution (NaOH) as a hydrolysis agent. Correlation: purity-size-morphology-microstructure versus synthesis parameters aims to establish the optimal parameters of the elaboration process. The experimental research was performed at different concentrations of the FeC13 precursor: 0.1 M, 0.4M, 0.7M, at a temperature of 65°C, and the addition of a 2MNaOH solution. In this paper, the influence of some process factors, such as concentration and temperature, on the following parameters was analyzed: the degree of purity, on the dimensions, on the morphology and microstructure of the iron oxide nanoparticles. This analysis was implemented through the following techniques: X-ray diffraction (XRD), electron microscopy scanning coupled with Energy-dispersive X-ray spectroscopy (SEM-EDS), respectively by obtaining infrared spectrum of absorption or emission of a solid (FTIR).

Applied Organometallic Chemistry, 2020

The synthesis, crystal structure and electrochemical properties of a Ni(II) Schiff base complex, ... more The synthesis, crystal structure and electrochemical properties of a Ni(II) Schiff base complex, [Ni(L)]PF 6 (where L is 2,4,9,11,11-pentamethyl-2,3,4 triaza-1-one-4-amine) are reported herein. The complex has been characterized by its electrochemical behavior, X-ray crystallographic structural analysis, physio-chemical methods and spectroscopic techniques. Electrospray mass spectroscopic analysis gives a dominant ion peak with m/ z = 296 which corresponds to the {[Ni(L)]PF 6-HPF 6 } ? fragment. Cyclic voltammograms for [Ni(L)]PF 6 , obtained in DMF (0.1 M Bu 4 NPF 6) at a glassy carbon electrode with a scan rate of 100 mV s-1 , exhibit reversible ([Ni II (L)] ? / [Ni I (L)]) reduction and chemically irreversible ([Ni II (L)] ? / [Ni III (L)] 2? ? electroactive product) oxidation processes at-2.05 and 0.62 V, respectively. The diffusion coefficient, calculated using the Randles-Sevcik relationship, is 9.7 9 10-6 cm 2 s-1. Electrochemical studies reveal that the Ni I reduced form of the complex is capable of catalyzing CO 2 reduction at a potential that is thermodynamically more favorable than for the reduced [Ni(N,N 0ethylenebis(acetylacetoneiminato)]complex. Spectroelectrochemical analyses following bulk electrolysis of [Ni(L)]PF 6 under CO 2 revealed the formation of oxalate and bicarbonate.

IOP Conference Series: Materials Science and Engineering, 2019

Nano-oxides attracted the attention of the reserchers due to their numerous applications. From th... more Nano-oxides attracted the attention of the reserchers due to their numerous applications. From this point of view, the development of new synthesis methods has become equally important for industry. The use of solar energy can become one of the ecological methods of obtaining nano-powders. Our paper presents the comparison of the morphology of nanopowders of Al-doped zinc oxide and Mn-doped copper oxide, obtained by physical vapour deposition using solar energy (SPVD), at different pressure and solar flux. The morphological characterization of doped oxide nanopowders synthesized by SPVD was performed by scanning electron microscopy.

Current Trends in Natural Sciences

Colonization of skin lesions with various infectious agents is still a major health threat. The m... more Colonization of skin lesions with various infectious agents is still a major health threat. The misuse and abuse of antibiotics and synthetic drugs has led to increased resistance of pathogens and therefore difficulties in treating these medical conditions, requiring the development of new materials with antimicrobial efficacy. Thus, the aim of the study was to determine the therapeutic potential of hydrogels based on plant extracts (Chelidonium majus L., Arnica montana L., Calendula officinalis L., Aristolochia clematitis L., Hippophae rhamnoides L.) and zinc oxide nanoparticles in skin lesions by assessing cytotoxicity and cell viability. The two types of zinc oxide nanoparticles were obtained at 100 atmospheres and oven dried as well as at 100 atmospheres and spray dried. The data from our study suggest that none of the hydrogels tested show a notable cytotoxic effect on fibroblast culture. Dilution of the stock product in all experimental samples resulted in a cell viability of ...

The 30th SIAR International Congress of Automotive and Transport Engineering, 2019

This study is focused on developing a method to analyze the strain of the steering tie rod capabl... more This study is focused on developing a method to analyze the strain of the steering tie rod capable to be used for numerical investigation. The strain is determined using two experimental methods: bonded strain gauge and Digital Image Correlations (DIC). Experimental data obtained by the two methods will be compared and correlated. In conclusion, the study will develop a procedure for complex investigations of the deformation state/conditions.

Current Trends in Natural Sciences, 2019

Two hydro-alcoholic extracts of Aronia melanocarpa berries were obtained by different extraction ... more Two hydro-alcoholic extracts of Aronia melanocarpa berries were obtained by different extraction techniques: classical solvent extraction by maceration with solvent, under stirring, for 10 hours and ultrasonic assisted extraction at 20 kHz for 5 minutes, respectively. In both cases the ratio dried vegetal material: hydro-alcoholic solvent mixture (3:1, v: v) was 1: 10 (g: g). The resulting extracts were analysed to evaluate their antioxidant capacity. An important antioxidant activity expressed by the amount of total polyphenols content and antiradical power it was shown for both extracts. The method using ultrasounds was more efficient leading to extracts richer in polyphenols (5376.947 mg GAE/10. 0g D.W.) and with higher antiradical power meaning higher percentage of inhibition of DPPH and lower EC50. Using this powerful extract, the synthesis of some silver nanoparticles was performed, and the results were confirmed by molecular absorption spectrometry (MAS) and scanning electron...

Surface and Coatings Technology, 2021

Abstract Mixed titanium‑aluminum oxide coatings were successfully grown on grade-2 commercially p... more Abstract Mixed titanium‑aluminum oxide coatings were successfully grown on grade-2 commercially pure titanium substrates by using plasma electrolytic oxidation technique. The mechanical features and the resistance against corrosion were attributed to microstructural, morphological and surface changes resulting from different preparation conditions. The formation of bulk metal oxides consisting of a dominant TiAl2O5/Ti2Al6O13 structure together with α-Al2O3 and γ-Al2O3 phases in the coatings accompanied by fully oxidized metal atoms on top of the surface showed a maximum 24.5 GPa hardness and 45 N adhesive critical load, respectively. Best corrosion performance of the coatings in 3.5% NaCl was found to be two orders of magnitude higher when compared to uncoated Ti.

In this paper we used X-Ray diffraction techniques in order to study the microstructural paramete... more In this paper we used X-Ray diffraction techniques in order to study the microstructural parameters of TiN thin films deposited on silicon substrate by cathodic arc method. In terms of preferred orientation, the texture for all TiN thin films can be described as || normal direction fiber texture. The residual stresses were evaluated using the crystallite group method, applicable for specimens exhibiting a crystallographic fiber texture being simultaneously strong and sharp.

Materials, 2021

Combined analysis methods such as optical microscopy (OM), cathodoluminescence (CL) microscopy, X... more Combined analysis methods such as optical microscopy (OM), cathodoluminescence (CL) microscopy, X-ray diffraction (XRD), and scanning electron microscopy–energy dispersive X-ray spectrometry (SEM–EDX) have made it possible to obtain the first physico-chemical data of Dacian potsherds, exhumed at the archeological site of Ocnița-Buridava, Romania; the samples were provided by the “Aurelian Sacerdoțeanu” County Museum Vâlcea, dating from the 2nd century BC to the 1st century AD. The mineralogical and petrographic analyses revealed two types of ceramic pastes, taking into account the granulometry of the inclusions and highlighting the choice of the potter for fabricating the ceramic either by wheel or by hand. All samples showed an abundance in quartz, mica (muscovite and biotite), and feldspars. These observations were confirmed by cathodoluminescence imagery, revealing heterogeneous pastes with varied granulometric distributions. The XRD patterns indicated the presence of the mineral...

Proceedings of the 4th International Congress of Automotive and Transport Engineering (AMMA 2018), 2018

This study is focused on developing of a material capable to be used for numerical prediction of ... more This study is focused on developing of a material capable to be used for numerical prediction of mechanical structures life time. A damage model was implemented starting from a classical stress-strain dataset and it is influence over the results was evaluated. An enhanced analysis of the strain field was achieved by using tensile testing on shaped specimens in conjunction with Digital Image Correlation (DIC). A specialized method, X-Ray Diffraction (XRD), for the investigation of the residual stresses was also used to correlate the strain field with the residual stresses stored by the deformed specimens.

Light Metals 2019, 2019

The purpose of this article is to better understand the behaviour of the residual stresses in alu... more The purpose of this article is to better understand the behaviour of the residual stresses in aluminium alloy plates, to control and minimize them by adjusting the quenching and the stretching process parameters. Residual stresses have usually the same role in a material as ordinary mechanical stresses, but while the stresses due to external loads can be calculated with a high degree of accuracy, the same thing cannot be said about residual stresses. The evolution of the residual stresses in the aluminium plates and the influence of the quenching and stretching process conditions was investigated by the Hole-Drilling method. The experiments were performed only on the industrial equipment. Plates with the same chemical composition were quenched by water spray or by immersion in water with or without agitation of the cooling medium. Also the plates quenched by water spray were unidirectional, bidirectional and successive stretchered. The results show the influence of the quenching con...

Numerical investigations of 3D printed structures under compressive loads using damage and fractu... more Numerical investigations of 3D printed structures under compressive loads using damage and fracture criterion: experiments, parameter identification and validation

2018 International Semiconductor Conference (CAS), 2018

In this study, CNT-PANI composites were prepared in soft chemical synthesis conditions using hydr... more In this study, CNT-PANI composites were prepared in soft chemical synthesis conditions using hydrothermal method. Our aim is to obtain CNT-PANI films with potential applications in VOC's detection, using an environmental friendly, low energy consumption technique: hydrothermal-electrochemical deposition of composite films. Thin films were characterized by AFM and FT-IR analyses.

Proceedings "New Challenges in Heat Treatment and Surface Engineering" (ISBN: 978-953-96459-9-9) ; Editors: Smoljan, Božo and Matijević Božidar ; Publisher: Croatian Society for Heat Treatment and Surface Engineering, Zagreb, 2009, pages: 215-220, 2009

Current Trends in Natural Sciences, 2020

In recent years, more and more studies have highlighted the potential of fruits of Aronia melanoc... more In recent years, more and more studies have highlighted the potential of fruits of Aronia melanocarpa (Michx.) Elliott for the pharmaceutical and cosmetic industry, due to the high content of polyphenols and anthocyanins. Currently, the use of agricultural production of Aronia melanocarpa is mainly done through the use of fruit juice or powders in the food industry. In the present study we set out to achieve a superior route of fruit valorization by obtaining extracts for the pharmaceutical and cosmetics industry. For ultrasound-assisted extraction, Aronia melanocarpa fruits were preprocessed (drying, grinding, sieving) and then subjected to ultrasonic-assisted solvent extraction. The study carried out in this phase of the experiment followed the influence of the concentration of the solvent (water/ethanol ratio) on the anthocyanin content and the chromatographic profile of the extract. The chromatographic profile was obtained using the HPTLC method. The analysis material was represented by 3 extracts obtained under various experimental conditions, from the species Aronia melanocarpa (Michx.) Elliot fruits. The best HPTLC chromatographic imprint was shown for Aronia fruit extracts prepared in 3:1 water-ethanol mixture, at amplitude of 40%. In the other experimental variants the anthocyanin content was low.

IOP Conference Series: Materials Science and Engineering, 2019

Rene 41, super alloy nickel base with aging hardening, presents an exceptional strength at high t... more Rene 41, super alloy nickel base with aging hardening, presents an exceptional strength at high temperatures, find used at temperatures above 871°C. After aging, the microstructure of the alloy is made up of solid solution and precipitates and the mechanical properties show a significant variation with the aging temperature. The researches presented in this paper aims to determine the influence of thermal shocks at 1000 ° C on the alloy microstructure and the hardness. The heat shocks were applied in the surface, with the aid of solar energy, in 3 and 6 cycles of 30s. Samples were characterized, in surface and in section, by hardness measurements, scanning electron microscopy and EDX. The variations in the hardness characteristics were correlated with the structural transformations induced by the thermal shocks applied to the surface.

International Journal of Mechanical Sciences, 2019

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service... more This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Highlights  analytical solution for the estimate of the mean crushing force is proposed for structures with polygonal and star shaped crosssection;  literature available data were investigated for the validation of proposed model;  nondimensional analysis of the mean crushing force was performed for the evaluation of the results predicted by the proposed analytical solution;  proposed analytical solution was compared with existing, specific analytical solutions.

Applied Surface Science, 2006

Nanostructures formed by Au nanoparticles on ZnO thin film surface are of interest for applicatio... more Nanostructures formed by Au nanoparticles on ZnO thin film surface are of interest for applications which include medical implants, gassensors, and catalytic systems. A frequency tripled Nd:YAG laser (l = 355 nm, t FWHM $ 10 ns) was used for the successive irradiation of the Zn and Au targets. The ZnO films were synthesized in 20 Pa oxygen pressure while the subsequent Au coverage was grown in vacuum. The obtained structures surface morphology, crystalline quality, and chemical composition depth profile were investigated by acoustic (dynamic) mode atomic force microscopy, X-ray diffraction, and wavelength dispersive X-ray spectroscopy. The surface is characterized by a granular morphology, with average grain diameters of a few tens of nanometers. The surface roughness decreases with the increase of the number of laser pulses applied for the irradiation of the Au target. The Au coverage reveals a predominant (1 1 1) texture, whereas the underlying ZnO films are c-axis oriented. A linear dependence was established between the thickness of the Au coverage and the number of laser pulses applied for the irradiation of the Au target.

Journal of Science and Arts

In an attempt to obtain as much data as possible about the fragmentary sword discovered in 2017 i... more In an attempt to obtain as much data as possible about the fragmentary sword discovered in 2017 in one of the most important Dacian sites (Ocnita, Vâlcea County), but also about the way in which the environment in which it was preserved for approximatively 2,000 years has influenced its conservation status, the methods of characterization applied aim to obtain results concerning, on the one hand, the composition of the material from which the weapon was made, and as far as possible the technique used by the blacksmith craftsmen, and on the other hand, the composition of the soil in which the weapon was deposited to see the way the soil influenced the conservation state in which the weapon was found. Several analytical techniques, such as optical macroscopy (OM), X-ray fluorescence spectrometry (XRF), X-ray CT scanning, X-ray diffraction (XRD), scanning electron microscopy with energy dispersive spectroscopy (SEM) were used in order to investigate the corrosion processes that aroused...

2021 13th International Conference on Electronics, Computers and Artificial Intelligence (ECAI), 2021

Recently, superparamagnetic nanomaterials have paying attention great interest for to their catal... more Recently, superparamagnetic nanomaterials have paying attention great interest for to their catalytic properties and their applications. The present paper aims to make a description from the point of view of morphological, microstructural, and chemical elemental analysis of iron oxide powder, obtained by hydrolytic synthesis, using iron (III) FeC13 chloride as precursor and sodium hydroxide solution (NaOH) as a hydrolysis agent. Correlation: purity-size-morphology-microstructure versus synthesis parameters aims to establish the optimal parameters of the elaboration process. The experimental research was performed at different concentrations of the FeC13 precursor: 0.1 M, 0.4M, 0.7M, at a temperature of 65°C, and the addition of a 2MNaOH solution. In this paper, the influence of some process factors, such as concentration and temperature, on the following parameters was analyzed: the degree of purity, on the dimensions, on the morphology and microstructure of the iron oxide nanoparticles. This analysis was implemented through the following techniques: X-ray diffraction (XRD), electron microscopy scanning coupled with Energy-dispersive X-ray spectroscopy (SEM-EDS), respectively by obtaining infrared spectrum of absorption or emission of a solid (FTIR).

Applied Organometallic Chemistry, 2020

The synthesis, crystal structure and electrochemical properties of a Ni(II) Schiff base complex, ... more The synthesis, crystal structure and electrochemical properties of a Ni(II) Schiff base complex, [Ni(L)]PF 6 (where L is 2,4,9,11,11-pentamethyl-2,3,4 triaza-1-one-4-amine) are reported herein. The complex has been characterized by its electrochemical behavior, X-ray crystallographic structural analysis, physio-chemical methods and spectroscopic techniques. Electrospray mass spectroscopic analysis gives a dominant ion peak with m/ z = 296 which corresponds to the {[Ni(L)]PF 6-HPF 6 } ? fragment. Cyclic voltammograms for [Ni(L)]PF 6 , obtained in DMF (0.1 M Bu 4 NPF 6) at a glassy carbon electrode with a scan rate of 100 mV s-1 , exhibit reversible ([Ni II (L)] ? / [Ni I (L)]) reduction and chemically irreversible ([Ni II (L)] ? / [Ni III (L)] 2? ? electroactive product) oxidation processes at-2.05 and 0.62 V, respectively. The diffusion coefficient, calculated using the Randles-Sevcik relationship, is 9.7 9 10-6 cm 2 s-1. Electrochemical studies reveal that the Ni I reduced form of the complex is capable of catalyzing CO 2 reduction at a potential that is thermodynamically more favorable than for the reduced [Ni(N,N 0ethylenebis(acetylacetoneiminato)]complex. Spectroelectrochemical analyses following bulk electrolysis of [Ni(L)]PF 6 under CO 2 revealed the formation of oxalate and bicarbonate.

IOP Conference Series: Materials Science and Engineering, 2019

Nano-oxides attracted the attention of the reserchers due to their numerous applications. From th... more Nano-oxides attracted the attention of the reserchers due to their numerous applications. From this point of view, the development of new synthesis methods has become equally important for industry. The use of solar energy can become one of the ecological methods of obtaining nano-powders. Our paper presents the comparison of the morphology of nanopowders of Al-doped zinc oxide and Mn-doped copper oxide, obtained by physical vapour deposition using solar energy (SPVD), at different pressure and solar flux. The morphological characterization of doped oxide nanopowders synthesized by SPVD was performed by scanning electron microscopy.

Current Trends in Natural Sciences

Colonization of skin lesions with various infectious agents is still a major health threat. The m... more Colonization of skin lesions with various infectious agents is still a major health threat. The misuse and abuse of antibiotics and synthetic drugs has led to increased resistance of pathogens and therefore difficulties in treating these medical conditions, requiring the development of new materials with antimicrobial efficacy. Thus, the aim of the study was to determine the therapeutic potential of hydrogels based on plant extracts (Chelidonium majus L., Arnica montana L., Calendula officinalis L., Aristolochia clematitis L., Hippophae rhamnoides L.) and zinc oxide nanoparticles in skin lesions by assessing cytotoxicity and cell viability. The two types of zinc oxide nanoparticles were obtained at 100 atmospheres and oven dried as well as at 100 atmospheres and spray dried. The data from our study suggest that none of the hydrogels tested show a notable cytotoxic effect on fibroblast culture. Dilution of the stock product in all experimental samples resulted in a cell viability of ...

The 30th SIAR International Congress of Automotive and Transport Engineering, 2019

This study is focused on developing a method to analyze the strain of the steering tie rod capabl... more This study is focused on developing a method to analyze the strain of the steering tie rod capable to be used for numerical investigation. The strain is determined using two experimental methods: bonded strain gauge and Digital Image Correlations (DIC). Experimental data obtained by the two methods will be compared and correlated. In conclusion, the study will develop a procedure for complex investigations of the deformation state/conditions.

Current Trends in Natural Sciences, 2019

Two hydro-alcoholic extracts of Aronia melanocarpa berries were obtained by different extraction ... more Two hydro-alcoholic extracts of Aronia melanocarpa berries were obtained by different extraction techniques: classical solvent extraction by maceration with solvent, under stirring, for 10 hours and ultrasonic assisted extraction at 20 kHz for 5 minutes, respectively. In both cases the ratio dried vegetal material: hydro-alcoholic solvent mixture (3:1, v: v) was 1: 10 (g: g). The resulting extracts were analysed to evaluate their antioxidant capacity. An important antioxidant activity expressed by the amount of total polyphenols content and antiradical power it was shown for both extracts. The method using ultrasounds was more efficient leading to extracts richer in polyphenols (5376.947 mg GAE/10. 0g D.W.) and with higher antiradical power meaning higher percentage of inhibition of DPPH and lower EC50. Using this powerful extract, the synthesis of some silver nanoparticles was performed, and the results were confirmed by molecular absorption spectrometry (MAS) and scanning electron...

Surface and Coatings Technology, 2021

Abstract Mixed titanium‑aluminum oxide coatings were successfully grown on grade-2 commercially p... more Abstract Mixed titanium‑aluminum oxide coatings were successfully grown on grade-2 commercially pure titanium substrates by using plasma electrolytic oxidation technique. The mechanical features and the resistance against corrosion were attributed to microstructural, morphological and surface changes resulting from different preparation conditions. The formation of bulk metal oxides consisting of a dominant TiAl2O5/Ti2Al6O13 structure together with α-Al2O3 and γ-Al2O3 phases in the coatings accompanied by fully oxidized metal atoms on top of the surface showed a maximum 24.5 GPa hardness and 45 N adhesive critical load, respectively. Best corrosion performance of the coatings in 3.5% NaCl was found to be two orders of magnitude higher when compared to uncoated Ti.

In this paper we used X-Ray diffraction techniques in order to study the microstructural paramete... more In this paper we used X-Ray diffraction techniques in order to study the microstructural parameters of TiN thin films deposited on silicon substrate by cathodic arc method. In terms of preferred orientation, the texture for all TiN thin films can be described as || normal direction fiber texture. The residual stresses were evaluated using the crystallite group method, applicable for specimens exhibiting a crystallographic fiber texture being simultaneously strong and sharp.

Materials, 2021

Combined analysis methods such as optical microscopy (OM), cathodoluminescence (CL) microscopy, X... more Combined analysis methods such as optical microscopy (OM), cathodoluminescence (CL) microscopy, X-ray diffraction (XRD), and scanning electron microscopy–energy dispersive X-ray spectrometry (SEM–EDX) have made it possible to obtain the first physico-chemical data of Dacian potsherds, exhumed at the archeological site of Ocnița-Buridava, Romania; the samples were provided by the “Aurelian Sacerdoțeanu” County Museum Vâlcea, dating from the 2nd century BC to the 1st century AD. The mineralogical and petrographic analyses revealed two types of ceramic pastes, taking into account the granulometry of the inclusions and highlighting the choice of the potter for fabricating the ceramic either by wheel or by hand. All samples showed an abundance in quartz, mica (muscovite and biotite), and feldspars. These observations were confirmed by cathodoluminescence imagery, revealing heterogeneous pastes with varied granulometric distributions. The XRD patterns indicated the presence of the mineral...

Proceedings of the 4th International Congress of Automotive and Transport Engineering (AMMA 2018), 2018

This study is focused on developing of a material capable to be used for numerical prediction of ... more This study is focused on developing of a material capable to be used for numerical prediction of mechanical structures life time. A damage model was implemented starting from a classical stress-strain dataset and it is influence over the results was evaluated. An enhanced analysis of the strain field was achieved by using tensile testing on shaped specimens in conjunction with Digital Image Correlation (DIC). A specialized method, X-Ray Diffraction (XRD), for the investigation of the residual stresses was also used to correlate the strain field with the residual stresses stored by the deformed specimens.

Light Metals 2019, 2019

The purpose of this article is to better understand the behaviour of the residual stresses in alu... more The purpose of this article is to better understand the behaviour of the residual stresses in aluminium alloy plates, to control and minimize them by adjusting the quenching and the stretching process parameters. Residual stresses have usually the same role in a material as ordinary mechanical stresses, but while the stresses due to external loads can be calculated with a high degree of accuracy, the same thing cannot be said about residual stresses. The evolution of the residual stresses in the aluminium plates and the influence of the quenching and stretching process conditions was investigated by the Hole-Drilling method. The experiments were performed only on the industrial equipment. Plates with the same chemical composition were quenched by water spray or by immersion in water with or without agitation of the cooling medium. Also the plates quenched by water spray were unidirectional, bidirectional and successive stretchered. The results show the influence of the quenching con...

Numerical investigations of 3D printed structures under compressive loads using damage and fractu... more Numerical investigations of 3D printed structures under compressive loads using damage and fracture criterion: experiments, parameter identification and validation

2018 International Semiconductor Conference (CAS), 2018

In this study, CNT-PANI composites were prepared in soft chemical synthesis conditions using hydr... more In this study, CNT-PANI composites were prepared in soft chemical synthesis conditions using hydrothermal method. Our aim is to obtain CNT-PANI films with potential applications in VOC's detection, using an environmental friendly, low energy consumption technique: hydrothermal-electrochemical deposition of composite films. Thin films were characterized by AFM and FT-IR analyses.

The 30th SIAR International Congress of Automotive and Transport Engineering, 2019

Developing a complex characterization method for analyzed material represent the focus of this st... more Developing a complex characterization method for analyzed material represent the focus of this study. We aimed to develop a method that can be used for numerical investigation of mechanical structures. The first test performed was tensile test (classical test), the material analysis continued with shear test and triaxiality. The measurements are achieved by Digital Image Correlation (DIC), a new technique for an for improved analysis of the strain field.