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Prof. Andrei Rotaru
1. University of Craiova, Department of Biology and Environmental Engineering, Str. A.I. Cuza, Nr. 13, 200585 Craiova, Romania

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Research Keywords & Expertise

0 Physical chemistry of materials, thermophysical properties of solids, thermal analysis and calorimetry, kinetics & thermodynamics of heterogeneous processes
0 Diffusional properties
0 Dynamic processes in relaxors
0 Structure-properties relation in electroceramics
0 Thin films of soft molecular compounds

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Physical chemistry of materials, thermophysical properties of solids, thermal analysis and calorimetry, kinetics & thermodynamics of heterogeneous processes
Thin films of soft molecular compounds

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Journal article
Published: 06 December 2020 in Molecules
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Two yellow bis-azo dyes containing anthracene and two azodiphenylether groups (BPA and BTA) were prepared, and an extensive investigation of their physical, thermal and biological properties was carried out. The chemical structure was confirmed by the FTIR spectra, while from the UV–Vis spectra, the quantum efficiency of the laser fluorescence at the 476.5 nm was determined to be 0.33 (BPA) and 0.50 (BTA). The possible transitions between the energy levels of the electrons of the chemical elements were established, identifying the energies and the electronic configurations of the levels of transition. Both crystals are anisotropic, the optical phenomenon of double refraction of polarized light (birefringence) taking place. Images of maximum illumination and extinction were recorded when the crystals of the bis-azo compounds rotated by 90° each, which confirms their birefringence. A morphologic study of the thin films deposited onto glass surfaces was performed, proving the good adhesion of both dyes. By thermal analysis and calorimetry, the melting temperatures were determined (~224–225 °C for both of them), as well as their decomposition pathways and thermal effects (enthalpy variations during undergoing processes); thus, good thermal stability was exhibited. The interaction of the two compounds with collagen in the suede was studied, as well as their antioxidant activity, advocating for good chemical stability and potential to be safely used as coloring agents in the food industry.

ACS Style

Carla Alice Carabet; Anca Moanță; Ion Pălărie; Gabriela Iacobescu; Andrei Rotaru; Marian Leulescu; Mariana Popescu; Petre Rotaru. Physical, Thermal and Biological Properties of Yellow Dyes with Two Azodiphenylether Groups of Anthracene. Molecules 2020, 25, 5757 .

AMA Style

Carla Alice Carabet, Anca Moanță, Ion Pălărie, Gabriela Iacobescu, Andrei Rotaru, Marian Leulescu, Mariana Popescu, Petre Rotaru. Physical, Thermal and Biological Properties of Yellow Dyes with Two Azodiphenylether Groups of Anthracene. Molecules. 2020; 25 (23):5757.

Chicago/Turabian Style

Carla Alice Carabet; Anca Moanță; Ion Pălărie; Gabriela Iacobescu; Andrei Rotaru; Marian Leulescu; Mariana Popescu; Petre Rotaru. 2020. "Physical, Thermal and Biological Properties of Yellow Dyes with Two Azodiphenylether Groups of Anthracene." Molecules 25, no. 23: 5757.

Article
Published: 10 October 2020 in Journal of Thermal Analysis and Calorimetry
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Department of Basic and Applied Science for Engineering, Sapienza University of Rome, Via Del Castro Laurenziano 7, 00161, Rome, Italy Stefano Vecchio Ciprioti Department of Biology and Environmental Engineering, University of Craiova, Str. A.I. Cuza Street, Nr. 13, 200585, Craiova, Romania Andrei Rotaru Department of Chemical Thermodynamics, Institute of Physical Chemistry, “Ilie Murgulescu” of the Romanian Academy, Str. Independentei, Nr. 202, 060021, Bucharest, Romania Andrei Rotaru Department of Civil Engineering and Architecture and INSTM UdR, University of Catania, V. le A. Doria 6, 95125, Catania, Italy Ignazio Blanco Department of Organic Chemical Technology, Faculty of Chemistry and Technology, University of Split, R. Boškovića 35, 21 000, Split, Croatia Matko Erceg You can also search for this author in PubMed Google Scholar You can also search for this author in PubMed Google Scholar You can also search for this author in PubMed Google Scholar You can also search for this author in PubMed Google Scholar Correspondence to Stefano Vecchio Ciprioti. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Reprints and Permissions Vecchio Ciprioti, S., Rotaru, A., Blanco, I. et al. Advancements of thermal analysis and calorimetry in Central-Eastern Europe and Mediterranean region. J Therm Anal Calorim (2020). https://doi.org/10.1007/s10973-020-10272-2 Download citation Published: 10 October 2020 DOI: https://doi.org/10.1007/s10973-020-10272-2

ACS Style

Stefano Vecchio Ciprioti; Andrei Rotaru; Ignazio Blanco; Matko Erceg. Advancements of thermal analysis and calorimetry in Central-Eastern Europe and Mediterranean region. Journal of Thermal Analysis and Calorimetry 2020, 142, 1601 -1604.

AMA Style

Stefano Vecchio Ciprioti, Andrei Rotaru, Ignazio Blanco, Matko Erceg. Advancements of thermal analysis and calorimetry in Central-Eastern Europe and Mediterranean region. Journal of Thermal Analysis and Calorimetry. 2020; 142 (5):1601-1604.

Chicago/Turabian Style

Stefano Vecchio Ciprioti; Andrei Rotaru; Ignazio Blanco; Matko Erceg. 2020. "Advancements of thermal analysis and calorimetry in Central-Eastern Europe and Mediterranean region." Journal of Thermal Analysis and Calorimetry 142, no. 5: 1601-1604.

Editorial
Published: 03 September 2020 in Ceramics International
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ACS Style

Andrei Rotaru; Stefano Vecchio Ciprioti; Luis A. Perez-Maqueda. Thermophysical Aspects of Functional Materials and Surfaces 2019 (TAFCS2). Ceramics International 2020, 46, 29357 .

AMA Style

Andrei Rotaru, Stefano Vecchio Ciprioti, Luis A. Perez-Maqueda. Thermophysical Aspects of Functional Materials and Surfaces 2019 (TAFCS2). Ceramics International. 2020; 46 (18):29357.

Chicago/Turabian Style

Andrei Rotaru; Stefano Vecchio Ciprioti; Luis A. Perez-Maqueda. 2020. "Thermophysical Aspects of Functional Materials and Surfaces 2019 (TAFCS2)." Ceramics International 46, no. 18: 29357.

Journal article
Published: 26 August 2020 in Ceramics International
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Ti-based composite materials with remarkable mechanical properties and good thermal stability were obtained and studied with the purpose of employment for producing resistant and versatile components in the automotive industry. The raw materials having the overall Ti80Mn8Al6Sn3Zr2C1 composition were prepared by mechanosynthesis from powders of comprising elements; after thermal processing and by following four different sintering pathways, both in the argon flow, the four samples (S1–S4) reached a specific composition of metallic and ceramic phases. Thermal analysis and calorimetry showed that the composite materials adsorb considerable amounts of argon, these being related to the obtained composition and microstructure. The results of the thermal study were used when choosing the thermal treatment conditions for sintering; in order to select the optimal processing conditions within the four different regimes of sintering for the raw materials and the final sample with the best functional properties, a comprehensive study for determining the composition, structure and morphological features was carried out by means of X-ray diffraction, energy-dispersive X-ray spectroscopy and scanning electron microscopy. Two samples (S1 & S4) of the obtained composite materials have increased porosity due to the presence of titanium aluminium carbides (Ti3AlC & Ti3AlC2) that are known as highly porous ceramics, therefore absorbing more argon during the preparation process. The roughness and wear tests showed that the best results (smallest roughness: Ra = 1.11 μm and smallest wear: w = 2.472·10−4 mm3 N−1 m−1) belong to the S2 sample sintered in argon for 15 min at 1100 °C and further calcinated at 1050 °C for 75 min.

ACS Style

Cristina Ileana Pascu; Ştefan Gheorghe; Andrei Rotaru; Claudiu Nicolicescu; Nicoleta Cioateră; Adrian Sorin Roșca; Daniela Sârbu; Petre Rotaru. Ti-based composite materials with enhanced thermal and mechanical properties. Ceramics International 2020, 46, 29358 -29372.

AMA Style

Cristina Ileana Pascu, Ştefan Gheorghe, Andrei Rotaru, Claudiu Nicolicescu, Nicoleta Cioateră, Adrian Sorin Roșca, Daniela Sârbu, Petre Rotaru. Ti-based composite materials with enhanced thermal and mechanical properties. Ceramics International. 2020; 46 (18):29358-29372.

Chicago/Turabian Style

Cristina Ileana Pascu; Ştefan Gheorghe; Andrei Rotaru; Claudiu Nicolicescu; Nicoleta Cioateră; Adrian Sorin Roșca; Daniela Sârbu; Petre Rotaru. 2020. "Ti-based composite materials with enhanced thermal and mechanical properties." Ceramics International 46, no. 18: 29358-29372.

Journal article
Published: 07 July 2020 in Molecules
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Enterosorbents are widely-used materials for human body detoxification, which function by immobilizing and eliminating endogenous and exogenous toxins. Here, activated carbons, obtained from the lignocellulosic raw vegetal materials of indigenous provenance, have been studied. Walnut shell and wood from local species of nuts and apple-trees were carbonized, and further activated at high temperatures with water vapors in a rotary kiln. A second activation was carried out, in a fluidized bed reactor, but for shorter times. The textural properties of the samples were determined from the adsorption isotherms of nitrogen at 77 K, allowing the obtaining of highly mesoporous materials, while the adsorption capacity permitted an essential rise of six to seven times in the maximal adsorption values of the metabolites, which was determined by the reactivation process. A kinetic study of vitamin B12 and creatinine immobilization was performed, the optimal immobilization time for the apple-tree wood reactivated carbons being 2 times longer than for those originating from walnut shells. An additional investigation was also performed in specific conditions that simulate the real environment of immobilization: the temperature of a febrile human body (at the temperature T = 38 °C) and the characteristic acidity of the urinary tract and stomach (at the pH of 5.68 and 2.53, respectively). The activated carbonic adsorbents studied here, together with the results of the immobilization studies, show that these procedures can conduct a good incorporation of some endogenous metabolic products, such as vitamin B12 and creatinine, therefore presenting a good opportunity for their use as forthcoming commercial enterosorbents.

ACS Style

Tudor Lupaşcu; Oleg Petuhov; Nina Ţîmbaliuc; Silvia Cibotaru; Andrei Rotaru. Adsorption Capacity of Vitamin B12 and Creatinine on Highly-Mesoporous Activated Carbons Obtained from Lignocellulosic Raw Materials. Molecules 2020, 25, 3095 .

AMA Style

Tudor Lupaşcu, Oleg Petuhov, Nina Ţîmbaliuc, Silvia Cibotaru, Andrei Rotaru. Adsorption Capacity of Vitamin B12 and Creatinine on Highly-Mesoporous Activated Carbons Obtained from Lignocellulosic Raw Materials. Molecules. 2020; 25 (13):3095.

Chicago/Turabian Style

Tudor Lupaşcu; Oleg Petuhov; Nina Ţîmbaliuc; Silvia Cibotaru; Andrei Rotaru. 2020. "Adsorption Capacity of Vitamin B12 and Creatinine on Highly-Mesoporous Activated Carbons Obtained from Lignocellulosic Raw Materials." Molecules 25, no. 13: 3095.

Article
Published: 02 July 2020 in Journal of Thermal Analysis and Calorimetry
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University of Craiova, Craiova, Romania Andrei Rotaru Institute of Physical Chemistry, “Ilie Murgulescu” of the Romanian Academy, Bucharest, Romania Andrei Rotaru Research Center for Thermal Analysis for Environmental Problems, West University of Timisoara, Timisoara, Romania Titus Vlase ICPE-CA National Institute for Research and Development in Electrical Engineering, Bucharest, Romania Petru Budrugeac Institute of Chemistry of the Republic of Moldova, Chişinău, Republic of Moldova Oleg Petuhov You can also search for this author in PubMed Google Scholar You can also search for this author in PubMed Google Scholar You can also search for this author in PubMed Google Scholar You can also search for this author in PubMed Google Scholar Correspondence to Andrei Rotaru. Reprints and Permissions Rotaru, A., Vlase, T., Budrugeac, P. et al. Recent developments in the field of Thermal Analysis and Calorimetry in Romania and Republic of Moldova. J Therm Anal Calorim (2020). https://doi.org/10.1007/s10973-020-09938-8 Download citation Published: 02 July 2020 DOI: https://doi.org/10.1007/s10973-020-09938-8

ACS Style

Andrei Rotaru; Titus Vlase; Petru Budrugeac; Oleg Petuhov. Recent developments in the field of Thermal Analysis and Calorimetry in Romania and Republic of Moldova. Journal of Thermal Analysis and Calorimetry 2020, 141, 1 -3.

AMA Style

Andrei Rotaru, Titus Vlase, Petru Budrugeac, Oleg Petuhov. Recent developments in the field of Thermal Analysis and Calorimetry in Romania and Republic of Moldova. Journal of Thermal Analysis and Calorimetry. 2020; 141 (3):1-3.

Chicago/Turabian Style

Andrei Rotaru; Titus Vlase; Petru Budrugeac; Oleg Petuhov. 2020. "Recent developments in the field of Thermal Analysis and Calorimetry in Romania and Republic of Moldova." Journal of Thermal Analysis and Calorimetry 141, no. 3: 1-3.

Journal article
Published: 29 January 2020 in Molecules
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Recent advancements in biomedicine have focused on designing novel and stable interfaces that can drive a specific cellular response toward the requirements of medical devices or implants. Among these, in recent years, electroactive polymers (i.e., polyvinylidene fluoride or PVDF) have caught the attention within the biomedical applications sector, due to their insolubility, stability in biological media, in vitro and in vivo non-toxicity, or even piezoelectric properties. However, the main disadvantage of PVDF-based bio-interfaces is related to the absence of the functional groups on the fluoropolymer and their hydrophobic character leading to a deficiency of cell adhesion and proliferation. This work was aimed at obtaining hydrophilic functional PVDF polymer coatings by using, for the first time, the one-step, matrix-assisted pulsed evaporation (MAPLE) method, testing the need of a post-deposition thermal treatment and analyzing their preliminary capacity to support MC3T3-E1 pre-osteoblast cell survival. As osteoblast cells are known to prefer rough surfaces, MAPLE deposition parameters were studied for obtaining coatings with roughness of tens to hundreds of nm, while maintaining the chemical properties similar to those of the pristine material. The in vitro studies indicated that all surfaces supported the survival of viable osteoblasts with active metabolisms, similar to the “control” sample, with no major differences regarding the thermally treated materials; this eliminates the need to use a secondary step for obtaining hydrophilic PVDF coatings. The physical-chemical characteristics of the thin films, along with the in vitro analyses, suggest that MAPLE is an adequate technique for fabricating PVDF thin films for further bio-applications.

ACS Style

Luminita Nicoleta Dumitrescu; Patricia Neacsu; Madalina G. Necula; Anca Bonciu; Valentina Marascu; Anisoara Cimpean; Antoniu Moldovan; Andrei Rotaru; Valentina Dinca; Maria Dinescu. Induced Hydrophilicity and In Vitro Preliminary Osteoblast Response of Polyvinylidene Fluoride (PVDF) Coatings Obtained via MAPLE Deposition and Subsequent Thermal Treatment. Molecules 2020, 25, 582 .

AMA Style

Luminita Nicoleta Dumitrescu, Patricia Neacsu, Madalina G. Necula, Anca Bonciu, Valentina Marascu, Anisoara Cimpean, Antoniu Moldovan, Andrei Rotaru, Valentina Dinca, Maria Dinescu. Induced Hydrophilicity and In Vitro Preliminary Osteoblast Response of Polyvinylidene Fluoride (PVDF) Coatings Obtained via MAPLE Deposition and Subsequent Thermal Treatment. Molecules. 2020; 25 (3):582.

Chicago/Turabian Style

Luminita Nicoleta Dumitrescu; Patricia Neacsu; Madalina G. Necula; Anca Bonciu; Valentina Marascu; Anisoara Cimpean; Antoniu Moldovan; Andrei Rotaru; Valentina Dinca; Maria Dinescu. 2020. "Induced Hydrophilicity and In Vitro Preliminary Osteoblast Response of Polyvinylidene Fluoride (PVDF) Coatings Obtained via MAPLE Deposition and Subsequent Thermal Treatment." Molecules 25, no. 3: 582.

Journal article
Published: 28 January 2020 in Polyhedron
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Seven new coordination polymers [Zn(I)2(4-bpmhz)]n (1), [Cd(I)2(4-bpmhz)]n (2), [Zn(I)2(3-bpmhz)]n (3), [Cd(I)2(3-bpmhz)2]n (4), [Zn(NO3)2(H2O)2(4-bpmhz)]n·0.5n(EtOH) (5), [Cd(NO3)2(4-bpmhz)3/2(MeOH)]n·0.5nH2O (6) and [Zn(NO3)2(3-bpmhz)2]n (7) were prepared following the reactions of the zinc and cadmium iodide or nitrate salts with the methylated azine ligands of the bis-monodentate N,N′-donor type, 1,2-bis(1-(pyridin-4-yl)ethylidene)hydrazine (4-bpmhz) and 1,2-bis(1-(pyridin-3-yl)ethylidene)hydrazine (3-bpmhz). The single-crystal X-ray diffraction studies show that compounds 1–5, and 7 display 1D chain structures, while compound 6 shows a 2D coordination network, and both 4-bpmhz and 3-bpmhz act as bidentate bridging ligands. The crystals 1 and 2 are isomorphous, and differ by the metal cation only. The single coordination chains in 1–3 have zigzag structures; they are linear in 5, while 4 and 7 display similar double-chain structures. The crystal packing in 5 and 6 provides cavities occupied by solvent molecules, ethanol and water. The compounds were characterized in the solid state and in solution by spectroscopic (FTIR, UV–Vis, NMR) methods; the solid state emissive properties were studied for all compounds, while their thermal stability and behaviour were investigated by thermogravimetry under inert atmosphere, while the thermochromism for several compounds was registered and discussed.

ACS Style

Vasile Lozovan; Victor Kravtsov; Elena Gorincioi; Andrei Rotaru; Eduard B. Coropceanu; Nikita Siminel; Marina S. Fonari. Chromism, positional, conformational and structural isomerism in a series of Zn(II) and Cd(II) coordination polymers based on methylated azine N,N′-donor linkers. Polyhedron 2020, 180, 114411 .

AMA Style

Vasile Lozovan, Victor Kravtsov, Elena Gorincioi, Andrei Rotaru, Eduard B. Coropceanu, Nikita Siminel, Marina S. Fonari. Chromism, positional, conformational and structural isomerism in a series of Zn(II) and Cd(II) coordination polymers based on methylated azine N,N′-donor linkers. Polyhedron. 2020; 180 ():114411.

Chicago/Turabian Style

Vasile Lozovan; Victor Kravtsov; Elena Gorincioi; Andrei Rotaru; Eduard B. Coropceanu; Nikita Siminel; Marina S. Fonari. 2020. "Chromism, positional, conformational and structural isomerism in a series of Zn(II) and Cd(II) coordination polymers based on methylated azine N,N′-donor linkers." Polyhedron 180, no. : 114411.

Article
Published: 05 October 2019 in Journal of Thermal Analysis and Calorimetry
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ACS Style

Andrei Rotaru; Dana Luca Motoc; Vlad T. Popa; Crisan Popescu. Thermal analysis and calorimetry in Europe. Journal of Thermal Analysis and Calorimetry 2019, 138, 1841 -1851.

AMA Style

Andrei Rotaru, Dana Luca Motoc, Vlad T. Popa, Crisan Popescu. Thermal analysis and calorimetry in Europe. Journal of Thermal Analysis and Calorimetry. 2019; 138 (3):1841-1851.

Chicago/Turabian Style

Andrei Rotaru; Dana Luca Motoc; Vlad T. Popa; Crisan Popescu. 2019. "Thermal analysis and calorimetry in Europe." Journal of Thermal Analysis and Calorimetry 138, no. 3: 1841-1851.

Article
Published: 04 September 2018 in Journal of Thermal Analysis and Calorimetry
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ACS Style

Andrei Rotaru; Tudor Lupaşcu; Florentin Paladi. Thermal analysis and calorimetry in the study of materials and processes for fundamental sciences and various applications in Central and Eastern Europe. Journal of Thermal Analysis and Calorimetry 2018, 134, 1 -5.

AMA Style

Andrei Rotaru, Tudor Lupaşcu, Florentin Paladi. Thermal analysis and calorimetry in the study of materials and processes for fundamental sciences and various applications in Central and Eastern Europe. Journal of Thermal Analysis and Calorimetry. 2018; 134 (1):1-5.

Chicago/Turabian Style

Andrei Rotaru; Tudor Lupaşcu; Florentin Paladi. 2018. "Thermal analysis and calorimetry in the study of materials and processes for fundamental sciences and various applications in Central and Eastern Europe." Journal of Thermal Analysis and Calorimetry 134, no. 1: 1-5.

Article
Published: 04 December 2017 in Journal of Thermal Analysis and Calorimetry
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ACS Style

Petru Budrugeac; Andrei Rotaru. Twenty-five years of Thermal Analysis and Calorimetry at the Romanian Academy. Journal of Thermal Analysis and Calorimetry 2017, 131, 113 -115.

AMA Style

Petru Budrugeac, Andrei Rotaru. Twenty-five years of Thermal Analysis and Calorimetry at the Romanian Academy. Journal of Thermal Analysis and Calorimetry. 2017; 131 (1):113-115.

Chicago/Turabian Style

Petru Budrugeac; Andrei Rotaru. 2017. "Twenty-five years of Thermal Analysis and Calorimetry at the Romanian Academy." Journal of Thermal Analysis and Calorimetry 131, no. 1: 113-115.

Erratum
Published: 04 February 2017 in Journal of Thermal Analysis and Calorimetry
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ACS Style

Romana Cerc Korošec; Andrei Rotaru. Erratum to: Thermal analysis and calorimetry in Central and Eastern Europe as a tool for solving diverse issues in different fields of science and applications. Journal of Thermal Analysis and Calorimetry 2017, 127, 2577 -2577.

AMA Style

Romana Cerc Korošec, Andrei Rotaru. Erratum to: Thermal analysis and calorimetry in Central and Eastern Europe as a tool for solving diverse issues in different fields of science and applications. Journal of Thermal Analysis and Calorimetry. 2017; 127 (3):2577-2577.

Chicago/Turabian Style

Romana Cerc Korošec; Andrei Rotaru. 2017. "Erratum to: Thermal analysis and calorimetry in Central and Eastern Europe as a tool for solving diverse issues in different fields of science and applications." Journal of Thermal Analysis and Calorimetry 127, no. 3: 2577-2577.

Journal article
Published: 01 August 2016 in Ceramics International
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This work reports on the microstructural and high-temperature impedance spectroscopy study of a family of dielectric ceramics Ba6MNb9O30 (M=Ga, Sc, In) of tetragonal tungsten bronze (TTB) structure with relaxor properties. For Ba6GaNb9O30 and Ba6InNb9O30 pellets, the SEM images have revealed good, dense internal microstructures, with well-bonded grains and only discrete porosity; in contrast Ba6ScNb9O30 pellets had a poorer microstructure, with many small and poorly-bonded grains gathered in agglomerates, resulting in significant continuous porosity and poorly defined grain boundary regions. The electroactive regions were characterised by the bulk and grain boundaries capacitances and resistances, while their contribution to the electrical conduction process was estimated by determining activation energies from the temperature (Arrhenius) dependence of both electric conductivities and time constants. For Ga and In analogues the electronic conductivity are dominated by the bulk response, while for Sc analogue, the poorly defined grain boundaries give a bulk-like response, mixing with the main bulk contribution.

ACS Style

Andrei Rotaru; Finlay Morrison. Microstructural and high-temperature impedance spectroscopy study of Ba6MNb9O30 (M=Ga, Sc, In) relaxor dielectric ceramics with tetragonal tungsten bronze structure. Ceramics International 2016, 42, 11810 -11821.

AMA Style

Andrei Rotaru, Finlay Morrison. Microstructural and high-temperature impedance spectroscopy study of Ba6MNb9O30 (M=Ga, Sc, In) relaxor dielectric ceramics with tetragonal tungsten bronze structure. Ceramics International. 2016; 42 (10):11810-11821.

Chicago/Turabian Style

Andrei Rotaru; Finlay Morrison. 2016. "Microstructural and high-temperature impedance spectroscopy study of Ba6MNb9O30 (M=Ga, Sc, In) relaxor dielectric ceramics with tetragonal tungsten bronze structure." Ceramics International 42, no. 10: 11810-11821.

Journal article
Published: 11 June 2016 in Journal of Thermal Analysis and Calorimetry
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Boric acid is a very important inorganic material with diverse uses in optoelectronics, petroleum industry, medicine, agriculture, etc. Recently, it was reported on the modification of the crystallization system of the triclinic boric acid (TBA) to hexagonal boric acid (HBA), when a special obtaining procedure is applied. In this paper, the thermokinetic stability of HBA novel material was comparatively studied with respect to the well-known TBA, in air flow atmosphere. Both HBA and TBA undergo a three-step overall thermal decomposition reaction (dehydration), following similar pathways; from the thermodynamic point of view HBA is more stable—decomposition temperatures and ΔH are higher in this case compared to those of TBA. The kinetic analysis was performed by means of the isoconversional methods, for each step of dehydration observing different thermokinetic regions. Higher thermal stability for HBA enables it to be employed at higher temperatures instead of TBA, explaining why the triclinic symmetry enhances the formation actually of the pseudo-hexagonal crystals as crystal habit at the macroscopic scale. Lower thermodynamic and kinetic stability of HBA makes it easier to be activated and thus more instable at the microstructural scale: this is an indirect proof of the TBA presence in the usual surrounding conditions and in the same time raises the probability for HBA molecules to slide onto their crystalline layers due to the lability of hydrogen bonds keeping them and thus increased potential to intercalate with other molecules. The present results open the possibility for promising applications of HBA as a better lubricant for various industries, while in the medical sector superior cleanser, antifungal and antibacterial properties may be foreseen.

ACS Style

Andrei Rotaru. Thermal and kinetic study of hexagonal boric acid versus triclinic boric acid in air flow. Journal of Thermal Analysis and Calorimetry 2016, 127, 755 -763.

AMA Style

Andrei Rotaru. Thermal and kinetic study of hexagonal boric acid versus triclinic boric acid in air flow. Journal of Thermal Analysis and Calorimetry. 2016; 127 (1):755-763.

Chicago/Turabian Style

Andrei Rotaru. 2016. "Thermal and kinetic study of hexagonal boric acid versus triclinic boric acid in air flow." Journal of Thermal Analysis and Calorimetry 127, no. 1: 755-763.

Journal article
Published: 31 May 2016 in Journal of Thermal Analysis and Calorimetry
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Kinetics of heterogeneous processes of materials is an important topic of thermal analysis field; it directly describes the dynamics of condensed matter systems, revealing “hot insights” of materials towards a better understanding of their structural, functional and transition-related properties. The advanced thermal and kinetic software by standard procedure TKS-SP 2.0 was successfully employed to perform kinetic computations, by making use of an extended spectrum of procedures, methods and discrimination criteria, it produces in real-time, high-volume and accurate sets of kinetic data from thermally induced processes. The discrimination between the kinetic models and the selection of the appropriate one is explained here in an in-depth study, employing the Perez-Maqueda et al. criterion under both integral and differential procedures in combination with the Gotor et al. master plots method. Perez-Maqueda et al. criterion describes the independence of the kinetic parameters from the heating rate, while the master plots method of Gotor et al. give the fastest way to check the kinetic models just by fitting in a continuous and visual manner the normalised transformation rate of a chemical or physical process with the relation ([f(α)·g(α)]/[f(α max)·g(α max)])—where the adjustment of the step of the kinetic model and of the values for the conversion degree at the maximal conversion rate inside the relation is performed. A working procedure is proposed to be applied for the step-by-step evaluations, discrimination and selection of the unique kinetic triplet {E, A, f(α)} corresponding to a certain investigated process.

ACS Style

Andrei Rotaru. Discriminating within the kinetic models for heterogeneous processes of materials by employing a combined procedure under TKS-SP 2.0 software. Journal of Thermal Analysis and Calorimetry 2016, 126, 919 -932.

AMA Style

Andrei Rotaru. Discriminating within the kinetic models for heterogeneous processes of materials by employing a combined procedure under TKS-SP 2.0 software. Journal of Thermal Analysis and Calorimetry. 2016; 126 (2):919-932.

Chicago/Turabian Style

Andrei Rotaru. 2016. "Discriminating within the kinetic models for heterogeneous processes of materials by employing a combined procedure under TKS-SP 2.0 software." Journal of Thermal Analysis and Calorimetry 126, no. 2: 919-932.

Journal article
Published: 06 January 2016 in Journal of Thermal Analysis and Calorimetry
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Tetragonal tungsten bronze (TTB) structures offer some promise as lead-free ferroelectrics and have an advantage of great flexibility in terms of accessible composition ranges due to the number of crystallographic sites available for chemical substitution. The ferroic properties of interest are coupled with strain, which will be important in the context of stability, switching dynamics and thin film properties. Coupling of strain with the ferroelectric order parameter gives rise to changes in elastic properties, and these have been investigated for a ceramic sample of Ba6GaNb9O30 (BGNO) by resonant ultrasound spectroscopy. Room temperature values of the shear and bulk moduli for BGNO are rather higher than for TTBs with related composition which are orthorhombic at room temperature, consistent with suppression of the ferroelectric transition. Instead, a broad, rounded minimum in the shear modulus measured at ~1 MHz is accompanied by a broad rounded maximum in acoustic loss near 115 K and signifies relaxor freezing behaviour. Elastic softening with falling temperature from room temperature, ahead of the freezing interval, is attributed to the development of dynamical polar nanoregions (PNRs), whilst the nonlinear stiffening below ~115 K is consistent with a spectrum of relaxation times for freezing of the PNR microstructure.

ACS Style

Andrei Rotaru; Jason A. Schiemer; Michael A. Carpenter. Elastic and anelastic relaxations accompanying relaxor ferroelectric behaviour of Ba6GaNb9O30 tetragonal tungsten bronze from resonant ultrasound spectroscopy. Journal of Thermal Analysis and Calorimetry 2016, 124, 571 -583.

AMA Style

Andrei Rotaru, Jason A. Schiemer, Michael A. Carpenter. Elastic and anelastic relaxations accompanying relaxor ferroelectric behaviour of Ba6GaNb9O30 tetragonal tungsten bronze from resonant ultrasound spectroscopy. Journal of Thermal Analysis and Calorimetry. 2016; 124 (2):571-583.

Chicago/Turabian Style

Andrei Rotaru; Jason A. Schiemer; Michael A. Carpenter. 2016. "Elastic and anelastic relaxations accompanying relaxor ferroelectric behaviour of Ba6GaNb9O30 tetragonal tungsten bronze from resonant ultrasound spectroscopy." Journal of Thermal Analysis and Calorimetry 124, no. 2: 571-583.

Journals
Published: 09 February 2015 in Dalton Transactions
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A series of isovalently A-site substituted relaxor dielectric tetragonal tungsten bronzes of general formula Ba6−x−ySrxCayGaNb9O30 were investigated.

ACS Style

Andrew J. Miller; Andrei Rotaru; Donna Arnold; Finlay D. Morrison. Effect of local A-site strain on dipole stability in A6GaNb9O30 (A = Ba, Sr, Ca) tetragonal tungsten bronze relaxor dielectrics. Dalton Transactions 2015, 44, 10738 -10745.

AMA Style

Andrew J. Miller, Andrei Rotaru, Donna Arnold, Finlay D. Morrison. Effect of local A-site strain on dipole stability in A6GaNb9O30 (A = Ba, Sr, Ca) tetragonal tungsten bronze relaxor dielectrics. Dalton Transactions. 2015; 44 (23):10738-10745.

Chicago/Turabian Style

Andrew J. Miller; Andrei Rotaru; Donna Arnold; Finlay D. Morrison. 2015. "Effect of local A-site strain on dipole stability in A6GaNb9O30 (A = Ba, Sr, Ca) tetragonal tungsten bronze relaxor dielectrics." Dalton Transactions 44, no. 23: 10738-10745.

Journal article
Published: 11 October 2014 in Journal of Thermal Analysis and Calorimetry
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New zinc(II) 2-aminobenzoate complexes with general formula Zn(2-NH2benz)2(L)2 (where 2-NH2benz is 2-aminobenzoate, and L is phenazone, N-methylnicotinamide, nicotinamide and isonicotinamide) were prepared and characterized by elemental analysis and by FTIR spectroscopy. The stability and thermal behaviour of the compounds were studied by thermal analysis techniques (TG/DTG, DTA), and the decomposition reactions were proposed. The decomposition of the studied compounds is always a multistep process, when after the release of the bioactive ligand, 2-aminobenzenecarbaldehyde, 2-aminobenzene and carbon dioxide were evolved. The solid intermediate compounds were confirmed by FTIR spectroscopy, and the volatile products were identified by mass spectrometry. The final solid product of thermal decompositions was zinc oxide, which was confirmed by XRD and FTIR analysis. The non-isothermal kinetic investigation of Zn(2-NH2benz)2(mnad)2 decomposition in air was performed by means of isoconversional methods, for a better understanding of the undergoing processes. The antimicrobial assay was carried out comparatively for the investigated compounds; they have higher biological activity towards Staphylococcus aureus, Escherichia coli and Candida albicans in comparison with zinc(II) 4-bromobenzoates.

ACS Style

Annamaria Krajnikova; Andrei Rotaru; Katarína Györyová; Katarína Homzová; Horia Octavian Manolea; Jana Kovářová; Daniela Hudecová. Thermal behaviour and antimicrobial assay of some new zinc(II) 2-aminobenzoate complex compounds with bioactive ligands. Journal of Thermal Analysis and Calorimetry 2014, 120, 73 -83.

AMA Style

Annamaria Krajnikova, Andrei Rotaru, Katarína Györyová, Katarína Homzová, Horia Octavian Manolea, Jana Kovářová, Daniela Hudecová. Thermal behaviour and antimicrobial assay of some new zinc(II) 2-aminobenzoate complex compounds with bioactive ligands. Journal of Thermal Analysis and Calorimetry. 2014; 120 (1):73-83.

Chicago/Turabian Style

Annamaria Krajnikova; Andrei Rotaru; Katarína Györyová; Katarína Homzová; Horia Octavian Manolea; Jana Kovářová; Daniela Hudecová. 2014. "Thermal behaviour and antimicrobial assay of some new zinc(II) 2-aminobenzoate complex compounds with bioactive ligands." Journal of Thermal Analysis and Calorimetry 120, no. 1: 73-83.

Journal article
Published: 25 September 2014 in Journal of Thermal Analysis and Calorimetry
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Guest Editors Dr. Andrei Rotaru INFLPR—National Institute for Laser, Plasma and Radiation Physics, Laser Department, Magurele (Ilfov), Bucharest, Romania [email protected] Prof. Daumantas Matulis Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Vilnius University, Vilnius, Lithuania [email protected] This compilation is based on the peer-reviewed and selected papers presented at CEEC-TAC2 The Central and Eastern European Committee for Thermal Analysis and Calorimetry (CEEC-TAC) was welcomed in the capital of Lithuania, Vilnius, from the 27th to the 30th of August 2013 as a successful meeting dedicated to new trends in thermal analysis and calorimetry (CEEC-TAC2). It came after the 1st CEEC-TAC meeting which was held in Craiova—Romania, between the 7th and 10th of September 2011, which gathered more than 300 participants and was considered a huge success. The city of Vilnius, which is the geographical center of Europe and the cross-point of various nations a ...

ACS Style

Andrei Rotaru; Daumantas Matulis. New Trends in Thermal Analysis and Calorimetry in Central and Eastern Europe. Journal of Thermal Analysis and Calorimetry 2014, 118, 585 -589.

AMA Style

Andrei Rotaru, Daumantas Matulis. New Trends in Thermal Analysis and Calorimetry in Central and Eastern Europe. Journal of Thermal Analysis and Calorimetry. 2014; 118 (2):585-589.

Chicago/Turabian Style

Andrei Rotaru; Daumantas Matulis. 2014. "New Trends in Thermal Analysis and Calorimetry in Central and Eastern Europe." Journal of Thermal Analysis and Calorimetry 118, no. 2: 585-589.

Journal article
Published: 01 September 2012 in Journal of Thermal Analysis and Calorimetry
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Guest Editors Andrei Rotaru INFLPR – National Institute for Laser Plasma and Radiation Physics Romania [email protected] Crisan Popescu DWI an der RWTH Aachen e.V. Germany [email protected] This compilation is based on the peer-reviewed and selected papers of CEEC-TAC1 The Central and Eastern European Committee for Thermal Analysis and Calorimetry (CEEC-TAC) has happily welcomed many scientists attending its first conference—CEEC-TAC1, that was hold from 7th to 10th of September 2011 in Craiova, Romania. The ever-growing community of Thermal Analysis and Calorimetry and all those interested to develop the field in the Central and Eastern European countries, made the organization of this new conference a desirable event. Every 2 years CEEC-TAC aims to gather scientists from Germany and Switzerland to Russia and Kazakhstan, and from the Baltic countries to the Balkans, Turkey and the Caucasus in a forum where all can meet, present their work, explain their results and discuss t

ACS Style

Andrei Rotaru; Crisan Popescu. Special Issue Advanced Thermal Science in Central-Eastern Europe. Journal of Thermal Analysis and Calorimetry 2012, 110, 1 -3.

AMA Style

Andrei Rotaru, Crisan Popescu. Special Issue Advanced Thermal Science in Central-Eastern Europe. Journal of Thermal Analysis and Calorimetry. 2012; 110 (1):1-3.

Chicago/Turabian Style

Andrei Rotaru; Crisan Popescu. 2012. "Special Issue Advanced Thermal Science in Central-Eastern Europe." Journal of Thermal Analysis and Calorimetry 110, no. 1: 1-3.