română ALEXANDRU BURCEA, TALAAT GABRIEL REZK-GAVRILĂ, EDWIN SEVER BECHIR BOGDAN CONSTANTIN COSTĂCHEL, LAURENȚA LELIA MIHAI
Abstract
A cervical abrasion lesion is represented by a concave surface, situated at the gum line area. The aim of this study was to compare the efficiency of three composite resins used for the rehabilitation of cervical abrasions. Cervical abrasion lesions were rehabilitated with Estelite Asterıa - Tokuyama, GrandioSO x-tra Bulk Fill - Voco, and Tetric EvoCeram Bulk Fill - Ivoclar Vivadent) composite resins. 111 abrasion cervical lesions were restored with the three aesthetic dental composites in the assessed patients (26). The assessments were realized at 6 days after the insertion of the restoration material (baseline), and then 6, 12 and 18 months after, according to the modified USPHS criteria regarding the colour stability, anatomical contour, surface texture, marginal adaptation and integrity, marginal discoloration, apparition of secondary caries, postoperative sensitivity, and retention of the restoration. The restored teeth with abrasion lesions were distributed in three groups divided by the used restorative material: group G1 (EA, abrasion lesions restored with Estelite Asterıa composite), group G2 (GSOx, restoration with GrandioSO x-tra Bulk Fill composite), and group G3 (TEC, restoration made with Tetric EvoCeram Bulk Fill composite). The comparative study was a split-mouth study. All three restorative dental materials presented good clinical results after 18 months, in all studied criterion, without significant differences.
Keywords
dental non-carious cervical abrasion, direct restorations, composites, modified USPHS criteria
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Year
2023
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Issue
53 (1)
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Pages
13-22
ECEM DOGAN, MUSTAFA SENGOR, OGUZHAN GUNDUZ, CEM BULENT USTUNDAG
Abstract
This study aims to obtain nanoparticles by electrospinning method using xanthan gum (XG) and gelatine (GEL) polymers. For the development of these nanoparticles, ten different groups were produced. In some groups, nanofiber was obtained instead of particles. The nanofiber formation was determined in the 10 wt% GEL, 12 wt% GEL, 3 wt% XG, 8 wt% GEL + 3 wt% XG. 12 wt% GEL + 0.1 wt% XG groups. 4 wt% GEL + 1 wt% XG and 8 wt% GEL + 3 wt% XG groups showed nanoparticles structure. To assess the nanofibers chemical properties, Fourier transform infrared spectroscopy (FTIR) were used. Scanning electron microscopy (SEM) was used to characterize mechanical and morphological properties. Physical properties and swelling behaviours were examined to analyse the samples. As a result of the swelling test, 3 wt% XG was degraded, 10 wt% and 12 wt% gelatin groups started to degrade after the fourth day. Our work deduced that GEL/XG nanoparticles could use for carrier purposes. Also, this study was beneficial in finding the right ratios in the production of nanoparticles and nanofibers from the XG/GEL mixture by electrospinning. In addition, proper electrospinning parameters in nanofiber and nanoparticles production are also important results of the study and will be further used in developing composite nanostructures with regenerative or drug release capability.
Keywords
gelatin; xanthan gum; electrospinning; particle; fiber
ANDREEA IONIŢĂ (AFILIPOAEI), ZINA VULUGA, FLORIN OANCEA, GEORGE-MIHAIL TEODORESCU, RALUCA AUGUSTA GABOR, CRISTIAN ANDI NICOLAE, MĂLINA DEȘLIU-AVRAM, JENICA PACEAGIU
Abstract
In the present work, composites based on recycled polypropylene (PPr) and 30% treated and untreated lignocellulosic waste were prepared. The recycled polypropylene comes from recovered surgical masks used during the COVID-19 pandemic, from which the elastic band and the metal strip have been removed. The lignocellulosic waste used as a reinforcing agent consisted of the depleted substrate from the culture of Pleurotus ostreatus fungi, being a sawdust enriched in chitin pellets of corn cobs treated with borhot from the brewing of beer. The composites with 30% of treated/untreated sawdust were obtained in dynamical conditions by melt processing. The effects of sawdust, both treated and untreated, on tensile properties (strength and modulus of elasticity), dynamic-mechanical properties (storage/loss modulus and loss factor), thermal conductivity and thermal stability were studied. The results showed improved thermal and mechanical properties of bio-composite materials based on recycled polypropylene from used face masks and sawdust, which can be used as construction materials.
Keywords
face mask, lignocellulosic agricultural waste, PP recycled, thermal insulation properties
G. VIGNESH KUMAR, S. UDHAYAKUMAR
Abstract
Increasing threads of the global warming and issues in disposals in municipal solid waste without compromising the mechanical properties the existing composite materials requires some additional materials. The traditional glass fiber, basalt fiber and epoxy based hybrid composite material is accommodate with bio waste tamarind seed polysaccharides and cashew nut frictional dust with different mesh with that the mechanical properties are improved based on the results of tensile, impact and flexural tests. The biodegradable test confirms the biodegradation of the fabricated samples with frictional dust.
Keywords
Frictional Dust, Hybrid biocomposite, biodegradation, tensile property, Tamarind seed polysaccharides
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Year
2023
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Issue
53 (2)
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Pages
103-110
.FLORENTINA MARILENA CLICINSCHI, DORINEL TĂLPEANU, ALINA IULIA DUMITRU, VIOLETA TSAKIRIS, GABRIELA BEATRICE SBÂRCEA, DELIA PĂTROI, MARINESCU VIRGIL EMANUEL
Abstract
The aim of the work is to obtain through the spark plasma sintering (SPS) technique, ceramic composite materials based on Si3N4 and SiC, with different sintering additions (Al2O3 and Y2O3) with improved mechanical properties. The spark plasma sintering process was carried out in vacuum at a pressure of 50 MPa, at temperatures between 1600-1800°C and a maximum sintering time of 5 minutes. In order to put in evidence the structural and morphological behavior of the obtained composites at different sintering temperature that lead to their improved mechanical properties, they were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. Physical-mechanical characteristics (apparent density, apparent porosity and Vickers hardness) were determined for all sintered samples. Structural analysis by X-ray diffraction, revealed the formation of two major phases α and β-Si3N4, with an increase of their crystallographic transformation from one phase to another (α→β) with the increasing of the sintering temperature. Si3N4 and SiC based ceramic composites sintered at 1800°C and with a 5wt.% Y2O3 content, showed a good correlation of physical-mechanical and structural characteristics, having a relative density of 93% of the theoretical density, Vickers hardness values of 18.39 GPa and bending strength of 336 MPa.
Keywords
Spark Plasma Sintering,Si3N4, SiC, ceramic composites, X-ray diffraction, scanning electron microscopy
IULIANA PAUN, CRISTINA ILEANA COVALIU- MIERLA, EUGENIU VASILE
Abstract
Benzalkonium chlorides are among the active ingredients of the products with biocidal properties used for disinfection of hands and surfaces. After use, a large part of benzalkonium chlorides end up in the wastewater from the treatment plants where they can cause imbalances of the biological treatment step by destroying the bacteria in the activated sludge. Having bactericidal properties, these pollutants are unlikely to be removed by conventional wastewater treatment techniques. In this paper we present an unconventional method for wastewater treatment using TiO2 nanomaterial with a particle size of 10 nm having the photocatalytic activity for degrading two components of benzalkonium chloride, namely tetradecyldimethyl benzyl ammonium chloride (C14-BAC) and hexadecyldimethylbenzyl ammonium chloride (C16-BAC) from wastewater. The concentration of the two compounds was analyzed using a high-performance liquid chromatograph equipped with a diode array detector (HPLC-DAD). The wastewater treatment yield was 100 %, and the half-life was for C14-BAC of 7.56 h and for C16-BAC of 10.67 h.
Keywords
benzalkonium chloride, nanomaterial, TiO2 powder, wastewater treatment
ANDRADA-ELENA ALECU, STEFANIA-ANDREEA GIRJOABA, MIHAELA BEREGOI, MIHAELA BACALUM, MINA RAILEANU, SORIN-ION JINGA, CRISTINA BUSUIOC
Abstract
In this work, polyvinylidene fluoride (PVDF) fibres loaded with mineral powders, such as titanium dioxide (TiO23xMgSi2Oy), were prepared by electrospinning polymeric suspensions containing 20 wt.% PVDF and 3 wt.% powder. The piezoelectric polymer was combined with powders having antibacterial, piezoelectric, or bioactive properties, respectively, in the desire to obtain multifunctional materials compatible with the requirements of the medical field. All powders were characterized in terms of morphology and crystalline structure, which confirmed the nanometric character of TiO223xMgSi2Oy. The final fibrous scaffolds were homogeneous, composed of individual fibres with a diameter below 1 μm and decorated with aggregates of inorganic particles, placed either inside the fibres or attached to their surface. The biological evaluation demonstrated the superiority of the composites towards the plain polymer in terms of cell viability.
Keywords
Polyvinylidene fluoride; Titanium dioxide; Barium titanate; Akermanite; Electrospinning; Tissue Engineering
DR.R.SHANMUGAM
Abstract
The modernization developments globally lead to an abundance of infrastructure progression. This progression is consequential to numerous sources of predicament like scarcity of construction resources on the other hand increases productivity thrown away from industry. Of late, managing scrap is the principal concern faced globally. The throwaway problem is the most significant issue facing the world as a source of ecological contamination. Recent growth in transportation has generated an immense number of motor vehicles creating an enormous quantum of scrap tyres. This paper investigates incorporating the salvage of scrap tyre rubber of coarse aggregate in M30 eco-friendly composite blocks as a fragmentary substitution. As per the recent government norms M30 eco-friendly composite is used for principally constructional works. This research is to appraise the accomplishment of steel slag as coarse aggregate in the fly-ash-based eco-friendly composite. Eco-friendly composite(EFC) is 100 % cement Scrap tyre rubber and steel slag were progressively incorporated with 0%, 5%, 10%, 15% ,and 20% to substitute coarse aggregate with sisal fiber in, 4% of fly ash. Properties of coarse aggregates, fine aggregates, fly ash and scrap tyre rubber were found. Paver Blocks were cast and tested for 7, 14 and 28 days of strength. The result shows that the compressive and flexural strength of M30 eco-friendly composite with scrap tyre rubber is 5% for Blocks is optimal. Laboratory tests were carried out and the conclusion was made based on the results. The outcome shows that the mechanical characteristics of M30 eco-friendly composite with scrap tyre rubber are 5% for eco-friendly composite (EFC) Blocks are most advantageous. Also, structural characteristics were studied.
Keywords
Eco-friendly composite, fly ash, Sisal fiber, Steel slag, Scrap tyre rubber
PAVEL TOPALĂ, ALEXANDR OJEGOV, VITALIE BEȘLIU, DANIELA RĂILEANU
Abstract
Micro- and nano-technology is nowadays a field of production that grows up vigorously and attempts to solve the material and energy crisis that has affected all mankind on the one hand, and, on the other hand, it comes with new solutions in miniaturization of the technique and solving the problems faced by the compatibility of existing materials with the living matter, i.e. it comes with apply for a better life. The recent studies regarding the interaction of surface materials with plasma pulsed electrical discharges caused by a solitary discharge have shown that under the action of PEDM the active surfaces of the parts applied in machine building, electronics, chemical industry, food industry, medicine, etc. micro-modifications of these surfaces can take place, along with the formation of 3D-structured carbon films with micrometric thicknesses, synthesis of amorphous films of oxides and hydroxides of nanometres thicknesses. The application of surface micro-geometry modifications ensures the increase of the thermoelectric current of the electrons up to 10 times, the surface-active resistance by 107 times, the resistance to corrosion in the aggressive media from 2 to 100 times.
Keywords
micro-, nanotechnologies, pellicle, film, corrosion, emission, resistance