Materials

Research

Jump to: Review

24 pages, 5699 KiB

Open AccessArticle

Improving the Hydrophobicity of Plasticized Polyvinyl Chloride for Use in an Endotracheal Tube

by Lavinia Marcut, Aurel George Mohan, Iuliana Corneschi, Elena Grosu, Gheorghe Paltanea, Ionela Avram, Alexandra Valentina Badaluta, Gabriel Vasilievici, Cristian-Andi Nicolae and Lia Mara Ditu

Materials 2023, 16(22), 7089; https://doi.org/10.3390/ma16227089 - 08 Nov 2023

Cited by 1 | Viewed by 837

Abstract

An endotracheal tube (ETT) is a greatly appreciated medical device at the global level with widespread application in the treatment of respiratory diseases, such as bronchitis and asthma, and in general anesthesia, to provide narcotic gases. Since an important quantitative request for cuffed [...] Read more.

An endotracheal tube (ETT) is a greatly appreciated medical device at the global level with widespread application in the treatment of respiratory diseases, such as bronchitis and asthma, and in general anesthesia, to provide narcotic gases. Since an important quantitative request for cuffed ETTs was recorded during the COVID-19 pandemic, concerns about infection have risen. The plasticized polyvinyl chloride (PVC) material used to manufacture ETTs favors the attachment of microorganisms from the human biological environment and the migration of plasticizer from the polymer that feeds the microorganisms and promotes the growth of biofilms. This leads to developing infections, which means additional suffering, discomfort for patients, and increased hospital costs. In this work, we propose to modify the surfaces of some samples taken from commercial ETTs in order to develop their hydrophobic character using surface fluorination by a plasma treatment in SF6 discharge and magnetron sputtering physical evaporation from the PTFE target. Samples with surfaces thus modified were subsequently tested using XPS, ATR-FTIR, CA, SEM + EDAX, profilometry, density, Shore A hardness, TGA-DSC, and biological antimicrobial and biocompatibility properties. The obtained results demonstrate a successful increase in the hydrophobic character of the plasticized PVC samples and biocompatibility properties. Full article

(This article belongs to the Special Issue State-of-the-Art Materials Science and Engineering in Romania 2023)

► Show Figures

Figure 1

14 pages, 9389 KiB

Open AccessArticle

Microstructural Characterization of Al_0.5CrFeNiTi High Entropy Alloy Produced by Powder Metallurgy Route

by Laura Elena Geambazu, Dorinel Tălpeanu, Robert Viorel Bololoi, Ciprian Alexandru Manea, Alina Elena Bololoi, Florin Miculescu, Delia Pătroi and Vasile Dănuţ Cojocaru

Materials 2023, 16(21), 7038; https://doi.org/10.3390/ma16217038 - 04 Nov 2023

Cited by 1 | Viewed by 738

Abstract

Alloys with superior properties represent the main topic of recent studies due to their effectiveness in reducing the cost of equipment maintenance and enhancing usage time, in addition to other benefits in domains such as geothermal, marine, and airspace. Al_0.5CrFeNiTi was [...] Read more.

Alloys with superior properties represent the main topic of recent studies due to their effectiveness in reducing the cost of equipment maintenance and enhancing usage time, in addition to other benefits in domains such as geothermal, marine, and airspace. Al_0.5CrFeNiTi was produced by solid state processing in a planetary ball mill, with the objective of obtaining a high alloying degree and a homogenous composition that could be further processed by pressing and sintering. The metallic powder was technologically characterized, indicating a particle size reduction following mechanical alloying processing when compared to the elemental raw powder materials. The microstructural analysis presented the evolution of the alloying degree during milling but also a compact structure with no major defects in the pressed and sintered bulk samples. The X-ray diffraction results confirmed the presence of face-centered cubic (FCC) and body-centered cubic (BCC) phases, predicted by the theoretical calculations, along with a hexagonal close-packed (HCP) phase, where the Al, Cr, Fe, Ni, and Ti phase was identified in both the alloyed powder material and sintered sample. Full article

(This article belongs to the Special Issue State-of-the-Art Materials Science and Engineering in Romania 2023)

► Show Figures

Figure 1

21 pages, 12495 KiB

Open AccessArticle

Co_xCrFeNiTi High-Entropy Alloys Prepared via Mechanical Alloying and Spark Plasma Sintering for Magnetron Sputtering Coatings

by Ciprian Alexandru Manea, Laura Elena Geambazu, Dorinel Tălpeanu, Virgil Marinescu, Gabriela Beatrice Sbârcea, Delia Pătroi, Radu Mihail Udrea, Magdalena Valentina Lungu and Mariana Lucaci

Materials 2023, 16(19), 6386; https://doi.org/10.3390/ma16196386 - 24 Sep 2023

Viewed by 1250

Abstract

The main objective of this study was to develop a high-entropy alloy (HEA) derived from the Co_xCrFeNiTi HEA system (x = 0.5, 1) for protective coatings using the magnetron sputtering method. In order to produce the high-entropy alloy targets required for [...] Read more.

The main objective of this study was to develop a high-entropy alloy (HEA) derived from the Co_xCrFeNiTi HEA system (x = 0.5, 1) for protective coatings using the magnetron sputtering method. In order to produce the high-entropy alloy targets required for the magnetron sputtering process, mechanically alloyed metallic powders were consolidated via spark plasma sintering (SPS). The microstructural analysis results of the HEA mixture presented morphology changes after 30 h of alloying, with the particles presenting uniform polygonal shapes and dimensions. Subsequently, 316L stainless steel (SS) specimens were coated via magnetron sputtering, comparing their composition with that of the sputtering targets used for deposition to establish stoichiometry. Microstructural analyses of the SPSed HEAs revealed no defects and indicated a uniform elemental distribution across the surface. Furthermore, the CoCrFeNiTi equiatomic alloy exhibited a nearly stoichiometric composition, both in the coating and the sputtering target. The XRD analysis results indicated that amorphous coatings were obtained for both Co_0.5CrFeNiTi and the CoCrFeNiTi HEA, and nanoindentation tests indicated that the CoCrFeNiTi HEA coating presented a hardness of 596 ± 22 HV, compared to the 570 ± 19 HV measured for Co_0.5CrFeNiTi, suggesting an improved wear resistance. Full article

(This article belongs to the Special Issue State-of-the-Art Materials Science and Engineering in Romania 2023)

► Show Figures

Figure 1

13 pages, 2395 KiB

Open AccessArticle

Mechanical Properties and Liquid Absorption of Calcium Phosphate Composite Cements

by Ioana Lacan, Marioara Moldovan, Codruta Sarosi, Stanca Cuc, Mihaela Pastrav, Ioan Petean and Razvan Ene

Materials 2023, 16(16), 5653; https://doi.org/10.3390/ma16165653 - 17 Aug 2023

Viewed by 1095

Abstract

Calcium phosphate cements present increased biocompatibility due to their chemical composition being similar to that of the hydroxyapatite in the hard tissues of the living body. It has certain limitations due to its poor mechanical properties, such as low tensile strength and increased [...] Read more.

Calcium phosphate cements present increased biocompatibility due to their chemical composition being similar to that of the hydroxyapatite in the hard tissues of the living body. It has certain limitations due to its poor mechanical properties, such as low tensile strength and increased brittleness. Thus, the optimal way to improve properties is through the design of novel composite cements. The purpose was fulfilled using a 25% hydroxyethyl methacrylate (HEMA) mixed with 3% urethane dimethacrzlate (UDMA) base matrix with various ratios of polyethylene glycol (PEG 400) and polycaprolactone (PCL). Mineral filler is based on tricalcium phosphate (TCP) with different chitosan ratio used as bio-response enhancer additive. Four mixtures were prepared: S0—unfilled polymer matrix; S1 with 50% TCP filler; S2 with 50% chitosan + TCP filler; and S3 with 17.5% chitosan + TCP mixed with 17.5% nano hydroxyapatite (HA). The mechanical properties testing revealed that the best compressive strength was obtained by S2, followed by S3, and the worst value was obtained for the unfilled matrix. The same tendency was observed for tensile and flexural strength. These results show that the novel filler system increases the mechanical resistance of the TCP composite cements. Liquid exposure investigation reveals a relative constant solubility of the used filler systems during 21 days of exposure: the most soluble fillers being S3 and S2 revealing that the additivated TCP is more soluble than without additives ones. Thus, the filler embedding mode into the polymer matrix plays a key role in the liquid absorption. It was observed that additive filler enhances the hydrophobicity of UDMA monomer, with the matrix resulting in the lowest liquid absorption values, while the non-additivated samples are more absorbent due to the prevalence of hydrolytic aliphatic groups within PEG 400. The higher liquid absorption was obtained on the first day of immersion, and it progressively decreased with exposure time due to the relative swelling of the surface microstructural features. The obtained results are confirmed by the microstructural changes monitored by SEM microscopy. S3 and S2 present a very uniform and compact filler distribution, while S1 presents local clustering of the TCP powder at the contact with the polymer matrix. The liquid exposure revealed significant pore formation in S0 and S1 samples, while S3 and S2 proved to be more resistant against superficial erosion, proving the best resistance against liquid penetration. Full article

(This article belongs to the Special Issue State-of-the-Art Materials Science and Engineering in Romania 2023)

► Show Figures

Figure 1

13 pages, 6364 KiB

Open AccessArticle

Metal–Ceramic Compatibility in Dental Restorations According to the Metallic Component Manufacturing Procedure

by Nazem Dawod, Marian Miculescu, Iulian Vasile Antoniac, Florin Miculescu and Doriana Agop-Forna

Materials 2023, 16(16), 5556; https://doi.org/10.3390/ma16165556 - 10 Aug 2023

Cited by 2 | Viewed by 1034

Abstract

In terms of production technology, metal–ceramic systems for dental restorations comply with a concrete algorithm, the efficiency of which is always dependent on the applications for which they are intended. The first stage involves obtaining metal support, followed by firing the ceramic on [...] Read more.

In terms of production technology, metal–ceramic systems for dental restorations comply with a concrete algorithm, the efficiency of which is always dependent on the applications for which they are intended. The first stage involves obtaining metal support, followed by firing the ceramic on the surface of the metal to meet the list of functional and aesthetic requirements of a future restoration. The compatibility of the two materials—the metal component and the ceramic component—must be ensured in several respects: chemical compatibility, thermo–chemical compatibility, and mechanical compatibility. Thus, there is a need to simulate the thermal behavior of the metal–ceramic couple in its processing to achieve appropriate dental prostheses. In this study, three types of Co–Cr metal frames were manufactured using three different production technologies: conventional casting, milling (CAM), and selective laser melting (SLM). Composition analyses, scanning electron microscopy (SEM), and microstructural analyses of the metal–ceramic interface for each type of production technology, as well as the determination of the hardness and the thermal expansion coefficients of experimental materials and three-point bending tests, were carried out in this study. Considering all these aspects, we demonstrated the influence of the technology of producing the metallic part of the metal–ceramic bonding process in dental prostheses. Full article

(This article belongs to the Special Issue State-of-the-Art Materials Science and Engineering in Romania 2023)

► Show Figures

Figure 1

28 pages, 4600 KiB

Open AccessArticle

In Vitro Evaluation of Ag- and Sr-Doped Hydroxyapatite Coatings for Medical Applications

by Elena Ungureanu, Alina Vladescu (Dragomir), Anca C. Parau, Valentina Mitran, Anisoara Cimpean, Mihai Tarcolea, Diana M. Vranceanu and Cosmin M. Cotrut

Materials 2023, 16(15), 5428; https://doi.org/10.3390/ma16155428 - 02 Aug 2023

Cited by 7 | Viewed by 1508

Abstract

Osseointegration plays the most important role in the success of an implant. One of the applications of hydroxyapatite (HAp) is as a coating for metallic implants due to its bioactive nature, which improves osteoconduction. The purpose of this research was to assess the [...] Read more.

Osseointegration plays the most important role in the success of an implant. One of the applications of hydroxyapatite (HAp) is as a coating for metallic implants due to its bioactive nature, which improves osteoconduction. The purpose of this research was to assess the in vitro behavior of HAp undoped and doped with Ag and/or Sr obtained by galvanostatic pulsed electrochemical deposition. The coatings were investigated in terms of chemical bonds, contact angle and surface free energy, electrochemical behavior, in vitro biomineralization in acellular media (SBF and PBS), and biocompatibility with preosteoblasts cells (MC3T3-E1 cell line). The obtained results highlighted the beneficial impact of Ag and/or Sr on the HAp. The FTIR spectra confirmed the presence of hydroxyapatite within all coatings, while in terms of wettability, the contact angle and surface free energy investigations showed that all surfaces were hydrophilic. The in vitro behavior of MC3T3-E1 indicated that the presence of Sr in the HAp coatings as a unique doping agent or in combination with Ag elicited improved cytocompatibility in terms of cell proliferation and osteogenic differentiation. Therefore, the composite HAp-based coatings showed promising potential for bone regeneration applications. Full article

(This article belongs to the Special Issue State-of-the-Art Materials Science and Engineering in Romania 2023)

► Show Figures

Figure 1

22 pages, 14995 KiB

Open AccessFeature PaperArticle

Effect of Fluoride Coatings on the Corrosion Behavior of Mg–Zn–Ca–Mn Alloys for Medical Application

by Tiberiu Bita, Aurora Antoniac, Ion Ciuca, Marian Miculescu, Cosmin Mihai Cotrut, Gheorghe Paltanea, Horatiu Dura, Iuliana Corneschi, Iulian Antoniac, Ioana Dana Carstoc and Alin Danut Bodog

Materials 2023, 16(13), 4508; https://doi.org/10.3390/ma16134508 - 21 Jun 2023

Cited by 3 | Viewed by 1547

Abstract

The most critical shortcoming of magnesium alloys from the point of view of medical devices is the high corrosion rate, which is not well-correlated with clinical needs. It is well- known that rapid degradation occurs when an implant made of Mg-based alloys is [...] Read more.

The most critical shortcoming of magnesium alloys from the point of view of medical devices is the high corrosion rate, which is not well-correlated with clinical needs. It is well- known that rapid degradation occurs when an implant made of Mg-based alloys is placed inside the human body. Consequently, the implant loses its mechanical properties and failure can occur even if it is not completely degraded. The corrosion products that appear after Mg-based alloy degradation, such as H₂ and OH⁻ can have an essential role in decreasing biocompatibility due to the H₂ accumulation process in the tissues near the implant. In order to control the degradation process of the Mg-based alloys, different coatings could be applied. The aim of the current paper is to evaluate the effect of fluoride coatings on the corrosion behavior of magnesium alloys from the system Mg–Zn–Ca–Mn potentially used for orthopedic trauma implants. The main functional properties required for the magnesium alloys to be used as implant materials, such as surface properties and corrosion behavior, were studied before and after surface modifications by fluoride conversion, with and without preliminary sandblasting, of two magnesium alloys from the system Mg–Zn–Ca–Mn. The experimental results showed that chemical conversion treatment with hydrofluoric acid is useful as a method of increasing corrosion resistance for the experimental magnesium alloys from the Mg–Zn–Ca–Mn system. Also, high surface free energy values obtained for the alloys treated with hydrofluoric acid correlated with wettability lead to the conclusion that there is an increased chance for biological factor adsorption and cell proliferation. Chemical conversion treatment with hydrofluoric acid is useful as a method of increasing corrosion resistance for the experimental Mg–Zn–Ca–Mn alloys. Full article

(This article belongs to the Special Issue State-of-the-Art Materials Science and Engineering in Romania 2023)

► Show Figures

Figure 1

Review

Jump to: Research

28 pages, 5464 KiB

Open AccessReview

Antimicrobial Solutions for Endotracheal Tubes in Prevention of Ventilator-Associated Pneumonia

by Lavinia Marcut, Veronica Manescu (Paltanea), Aurora Antoniac, Gheorghe Paltanea, Alina Robu, Aurel George Mohan, Elena Grosu, Iuliana Corneschi and Alin Danut Bodog

Materials 2023, 16(14), 5034; https://doi.org/10.3390/ma16145034 - 17 Jul 2023

Viewed by 3154

Abstract

Ventilator-associated pneumonia is one of the most frequently encountered hospital infections and is an essential issue in the healthcare field. It is usually linked to a high mortality rate and prolonged hospitalization time. There is a lack of treatment, so alternative solutions must [...] Read more.

Ventilator-associated pneumonia is one of the most frequently encountered hospital infections and is an essential issue in the healthcare field. It is usually linked to a high mortality rate and prolonged hospitalization time. There is a lack of treatment, so alternative solutions must be continuously sought. The endotracheal tube is an indwelling device that is a significant culprit for ventilator-associated pneumonia because its surface can be colonized by different types of pathogens, which generate a multispecies biofilm. In the paper, we discuss the definition of ventilator-associated pneumonia, the economic burdens, and its outcomes. Then, we present the latest technological solutions for endotracheal tube surfaces, such as active antimicrobial coatings, passive coatings, and combinatorial methods, with examples from the literature. We end our analysis by identifying the gaps existing in the present research and investigating future possibilities that can decrease ventilator-associated pneumonia cases and improve patient comfort during treatment. Full article

(This article belongs to the Special Issue State-of-the-Art Materials Science and Engineering in Romania 2023)

► Show Figures