Valentin Gurgu

Dr. Valentin Gurgu


Research Focus & Metrics

Academic Career Length

9Years (2018-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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26 April 2024 in Polymers
Verified
Journal Article
Open access
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MBMarius Bumbac
Marius Bumbac
CNCristina Mihaela Nicolescu
Cristina Mihaela Nicolescu
Traian ZaharescuTraian Zaharescu
Traian Zaharescu
VGValentin Gurgu
Valentin Gurgu
CBCostel Bumbac
Costel Bumbac
CDCrinela Dumitrescu
Crinela Dumitrescu
The preparation of polymer composites that incorporate material of a biogenic nature in the polymer matrices may lead to a reduction in fossil polymer consumption and a potentially higher biodegradability. Furthermore, microalgae biomass as biogenic filler has the advantage of fast growth and high tolerance to different types of culture media with higher production yields than those provided by the biomass of terrestrial crops. On the other hand, algal biomass can be a secondary product in wastewater treatment processes. For the present study, an SBS polymer composite (SBSC) containing 25% (w/w) copolymer SBS1 (linear copolymer: 30% styrene and 70% butadiene), 50% (w/w) copolymer SBS2 (linear copolymer: 40% styrene and 60% butadiene), and 25% (w/w) paraffin oil was prepared. Arthrospira platensis biomass (moisture content 6.0 ± 0.5%) was incorporated into the SBSC in 5, 10, 20, and 30% (w/w) ratios to obtain polymer composites with spirulina biomass. For the biodegradation studies, the ISO 14855-1:2012(E) standard was applied, with slight changes, as per the specificity of our experiments. The degradation of the studied materials was followed by quantitatively monitoring the CO2 resulting from the degradation process and captured by absorption in NaOH solution 0.5 mol/L. The structural and morphological changes induced by the industrial composting test on the materials were followed by physical–mechanical, FTIR, SEM, and DSC analysis. The obtained results were compared to create a picture of the material transformation during the composting period. Thus, the collected data indicate two biodegradation processes, of the polymer and the biomass, which take place at the same time at different rates, which influence each other. On the other hand, it is found that the material becomes less ordered, with a sponge-like morphology; the increase in the percentage of biomass leads to an advanced degree of degradation of the material. The FTIR analysis data suggest the possibility of the formation of peptide bonds between the aromatic nuclei in the styrene block and the molecular residues resulting from biomass biodegradation. It seems that in industrial composting conditions, the area of the polystyrene blocks from the SBS-based composite is preferentially transformed in the process.

28 March 2023 in Processes
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Journal Article
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ODOtilia Elena Dragomir
Otilia Elena Dragomir
FDFlorin Dragomir
Florin Dragomir
MPMarius-Adrian Păun
Marius-Adrian Păun
ODOctavian Duca
Octavian Duca
VGValentin Gurgu
Valentin Gurgu
IDIoan-Cătălin Drăgoi
Ioan-Cătălin Drăgoi
In recent years, most of the research in the field of smart grids integrating renewable energy sources assumed energy efficiency as a scheduling objective. However, the aspects of energy consumption or energy demand have not been described clearly, even though they have been proven to be an effective way of reducing energy consumption. In this context, this study aimed to cover a key research challenge in the field, such as the development of an intelligent strategy for solving energy consumption scheduling problems. The added value of our proposal consists of classifying individual consumption profiles assigned to each operation cycle phase, instead of considering an average of non-varying consumption of household appliances. Within this hybrid approach, the proposed explainable system, based on self-organizing maps of neural networks, fuzzy clustering algorithm, and scheduling technics, correlates the complex interrelation between power generated from renewable energy sources in a smart grid, prosumers’ load behaviors, and the consumption profile of controllable or uncontrollable appliances. The tests were made using green energy consumption and production from real monitored data sets. The load-shifting algorithm that was used to reduce energy consumption from the national energy grid proved its effectiveness. In fact, consumers paid 25% less for the energy they used from the national energy grid during the times when the amount of electricity produced from renewable sources was reduced as a result of weather conditions.

1 April 2021 in Studies in Informatics and Control
Verified
Journal Article
Closed access
ODOctavian Duca
Octavian Duca
CBClaudiu Bidică
Claudiu Bidică
Minca EugeniaMinca Eugenia
Minca Eugenia
VGValentin Gurgu
Valentin Gurgu
MPMarius-Adrian Păun
Marius-Adrian Păun
FDFlorin Dragomir
Florin Dragomir

29 April 2024 in Polymers
Verified
Journal Article
Open access
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MBMarius Bumbac
Marius Bumbac
CNCristina Mihaela Nicolescu
Cristina Mihaela Nicolescu
Traian ZaharescuTraian Zaharescu
Traian Zaharescu
CBCostel Bumbac
Costel Bumbac
EMElena Elisabeta Manea
Elena Elisabeta Manea
CDCrinela Dumitrescu
Crinela Dumitrescu
Bio-fillers are intensively studied for advanced polymer composite circular design and production. In this context, the algal biomass may be considered an important and relatively low-cost resource, when harvested as a by-product from wastewater treatment plants. The biomass of the algal species Chlorella vulgaris is frequently used in this type of environmental process, and its macro constituents’ composition ranges from around 15–25% carbohydrates, 10–20% lipids, and 50–60% proteins. Poly (styrene-butadiene-styrene) (SBS) copolymers have a matrix composed of glassy polystyrene domains connected by flexible polybutadiene segments. Although the physical-mechanical properties of SBS copolymers recommend them for many industrial applications, they have the drawback of low biodegradability. This study aimed to assess the aerobic biodegradability of polymer composites by integrating biomass from Chlorella vulgaris at varying mass percentages of 5, 10, and 20% into SBS copolymer composites. Biodegradation tests were conducted under industrial composting conditions (58 °C and 50% relative humidity) for 180 days. The biodegradability of materials was evaluated by measuring the CO2 produced in each vessel during the study period. Potential correlations between the amount of carbon dioxide released and the percentage of biomass added to the polymer matrix were examined. Structural and morphological changes were assessed using Fourier Transform infrared spectroscopy (FTIR), thermal analysis (DSC), and scanning electron microscopy (SEM). Physical and chemical testing revealed a decrease in sample density after the industrial composting test, along with noticeable changes in melt flow index (MFI). The observed physical and chemical changes, coupled with FTIR, SEM, and DSC data, indicate increased cross-linking and higher porosity in biodegraded polymer structures with higher biomass content. This behavior is likely due to the formation of cross-linked connections between polymer chains and polypeptide chains resulting from protein degradation, enhancing connections between polystyrene units facilitated by peptide bonds with the benzene units of the styrene blocks within the polymer matrix.

17 May 2018 in Bulletin of Materials Science
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Journal Article
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Ioan Alin BucuricaIoan Alin Bucurica
Ioan Alin Bucurica
IPIon Popescu
Ion Popescu
Cristiana RadulescuCristiana Radulescu
Cristiana Radulescu
GCGheorghe Valerica Cimpoca
Gheorghe Valerica Cimpoca
Ioana-Daniela DulamaIoana-Daniela Dulama
Ioana-Daniela Dulama
DLDorin LET
Dorin LET

13 December 2018
Verified
Book Chapter
Open access
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Rodica-Mariana IonRodica-Mariana Ion
Rodica-Mariana Ion
VGValentin Gurgu
Valentin Gurgu
Ioan Alin BucuricaIoan Alin Bucurica
Ioan Alin Bucurica
SSSofia Slamnoiu-Teodorescu
Sofia Slamnoiu-Teodorescu
Ioana-Daniela DulamaIoana-Daniela Dulama
Ioana-Daniela Dulama
Anca Irina GheboianuAnca Irina Gheboianu
Anca Irina Gheboianu
Nowadays, there is a lack of knowledge regarding the traditional construction technology used in many of some important monuments in Romania. To address this limitation and to assist in their conservation and restoration, this study documents the existing condition of different historic structures. Methods and applications for 3D scanning, image scanning and no-contact and non-destructive methods are applied in this paper for structural analysis of the stuccoes from a patrimony building (Fântaneanu House, Slatina). To record and document the condition of this house, the laser scanning is used in order to identify the initial size and shape of some damaged parts of the monument. Advancement in diagnosis methods (spectral and microscopic analytical methods) for the conservation/restoration of this patrimony building.