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1.
Chemosphere ; 282: 131066, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34470152

RESUMO

Copper ion (Cu2+), a common corrosion product released from copper pipes, is widely present in water distribution system (WDS). Cu2+ was confirmed to be capable to catalyze the decay of monochloramine (NH2Cl), which is a commonly used disinfectant and need to maintain a minimum concentration in WDS. Cu2+ and NH2Cl form a system in WDS and their interaction with other substances in WDS is unclear. In this study, the performance of Cu2+/NH2Cl system on degradation of trace pollutants, taking carbamazepine (CBZ) as an example, in WDS was investigated, and significant promotion on CBZ degradation was observed. The acceleration was due to the generation of Cl, OH and other oxidants, which were identified by scavenge experiments. CBZ degradation in Cu2+/NH2Cl system was highly pH-dependent, because the catalytic effect of Cu2+ can only work at low pH (Cu2+ precipitating at pH > 6.0). The removal of CBZ increased with the concentration of Cu2+ increasing. Water matrix (NOM, HCO3- and Br-) can inhibit the removal of CBZ in Cu2+/NH2Cl system. Further, five disinfection byproducts (DBPs), namely, trichloromethane (TCM), dichloroacetonitrile (DCAN), dichloroacetone (DCP), trichloronitromethane (TCNM) and trichloroacetone (TCP), were detected in chloramination in the presence/absence of Cu2+. Compared with chloramination without Cu2+, the cytotoxicity and genotoxicity of formed DBPs increased significantly in the presence of Cu2+, indicating that the chemical safety in WDS deserves more attention.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Carbamazepina , Cobre , Corrosão , Desinfecção , Halogenação , Água , Poluentes Químicos da Água/análise
2.
Int J Mol Sci ; 22(15)2021 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-34361065

RESUMO

Chitosan coatings are deposited on the surface of Mg20Zn magnesium alloy by means of the spin coating technique. Their structure was investigated using Fourier Transform Infrared Spectroscopy (FTIR) an X-ray photoelectron spectroscopy (XPS). The surface morphology of the magnesium alloy substrate and chitosan coatings was determined using Scanning Electron Microscope (FE-SEM) analysis. Corrosion tests (linear sweep voltamperometry and chronoamperometry) were performed on uncoated and coated magnesium alloy in the Hank's solution. In both cases, the hydrogen evolution method was used to calculate the corrosion rate after 7-days immersion in the Hank's solution at 37 °C. It was found that the corrosion rate is 3.2 mm/year and 1.2 mm/year for uncoated and coated substrates, respectively. High corrosion resistance of Mg20Zn alloy covered by multilayer coating (CaP coating + chitosan water glass) is caused by formation of CaSiO3 and Ca3(PO4)2 compounds on its surface.


Assuntos
Ligas/química , Quitosana/química , Materiais Revestidos Biocompatíveis/química , Magnésio/química , Zinco/química , Fenômenos Bioquímicos , Corrosão , Propriedades de Superfície
3.
Int J Mol Sci ; 22(16)2021 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-34445794

RESUMO

Xenogeneic biomaterials Cerbone® and OsteoBiol® are widely used in oral implantology. In dental practice, xenogeneic biomaterial is usually combined with autologous bone to provide bone volume stability needed for long-term dental implants. Magnesium alloy implants dissolve and form mineral corrosion layer that is directly in contact with bone tissue, allowing deposition of the newly formed bone. CSBD heals by intramembranous ossification and therefore is a convenient model for analyses of ostoconductive and osteoinductive properties of different type of biomaterials. Magnesium alloy-enriched biomaterials have not yet been applied in oral implantology. Therefore, the aim of the current study was to investigate biological properties of potentially new bovine xenogeneic biomaterial enriched with magnesium alloy in a 5 mm CSBD model. Osteoconductive properties of Cerabone®, Cerabone® + Al. bone, and OsteoBiol® were also analyzed. Dynamics of bone healing was followed up on the days 3, 7, 15, 21, and 30. Calvary bone samples were analyzed by micro-CT, and values of the bone morphometric parameters were assessed. Bone samples were further processed for histological and immunohistochemical analyses. Histological observation revealed CSBD closure at day 30 of the given xenogeneic biomaterial groups, with the exception of the control group. TNF-α showed high intensity of expression at the sites of MSC clusters that underwent ossification. Osx was expressed in pre-osteoblasts, which were differentiated into mature osteoblasts and osteocytes. Results of the micro-CT analyses showed linear increase in bone volume of all xenogeneic biomaterial groups and also in the control. The highest average values of bone volume were found for the Cerabone® + Mg group. In addition, less residual biomaterial was estimated in the Cerabone® + Mg group than in the Cerabone® group, indicating its better biodegradation during CSBD healing. Overall, the magnesium alloy xenogeneic biomaterial demonstrated key properties of osteoinduction and biodegradidibility during CSBD healing, which is the reason why it should be recommended for application in clinical practice of oral implantology.


Assuntos
Ligas/farmacologia , Materiais Biocompatíveis/farmacologia , Osso e Ossos/efeitos dos fármacos , Magnésio/farmacologia , Cicatrização/efeitos dos fármacos , Animais , Regeneração Óssea/efeitos dos fármacos , Substitutos Ósseos/farmacologia , Bovinos , Corrosão , Hidroxiapatitas/farmacologia , Teste de Materiais/métodos , Minerais/farmacologia , Osteoblastos/efeitos dos fármacos , Osteócitos/efeitos dos fármacos , Osteogênese/efeitos dos fármacos , Próteses e Implantes , Ratos , Microtomografia por Raio-X/métodos
4.
Science ; 373(6557): 857-858, 2021 08 20.
Artigo em Inglês | MEDLINE | ID: mdl-34413226

Assuntos
Ligas , Magnésio , Corrosão , Humanos
5.
Environ Pollut ; 286: 117556, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34438488

RESUMO

In the present study, produced water sample collected from the Indian crude oil reservoir is used to enrich the bacterial communities. The impact of these enriched bacterial communities on the biodegradation of crude oil, biofilm formation, and biocorrosion process are elucidated. A crude oil degradation study is carried out with the minimal salt medium and 94% of crude oil was utilized by enriched bacterial communities. During the crude oil degradation many enzymes including alkane hydroxylase, alcohol dehydrogenase, and lipase are playing a key role in the biodegradation processes. The role of enriched bacterial biofilm on biocorrosion reactions are monitored by weight loss studies and electrochemical analysis. Weight loss study revealed that the biotic system has vigorous corrosion attacks compared to the abiotic system. Both AC-Impedance and Tafel analysis confirmed that the nature of the corrosion reaction take place in the biotic system. Very less charge transfer resistance and higher corrosion current are observed in the biotic system than in the abiotic system. Scanning electron microscope confirms that the dense biofilm formation favoured the pitting type of corrosion. X-ray diffraction analysis confirms that the metal oxides formed in the corrosion systems (biotic). From the metagenomic analysis of the V3-V4 region revealed that presence of diverse bacterial communities in the biofilm, and most of them are uncultured/unknown. Among the known genus, Bacillus, Halomonas, etc are dominant in the enriched bacterial biofilm sample. From this study, we conclude that the uncultured bacterial strains are found to be playing a key role in the pitting type of corrosion and they can utilize crude oil hydrocarbons, which make them succeeded in extreme oil reservoir environments.


Assuntos
Petróleo , Bactérias/genética , Biodegradação Ambiental , Biofilmes , Corrosão
6.
Sensors (Basel) ; 21(12)2021 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-34207959

RESUMO

Corrosion identification and repair is a vital task in aircraft maintenance to ensure continued structural integrity. Regarding fuselage lap joints, typically, visual inspections are followed by non-destructive methodologies, which are time-consuming. The visual inspection of large areas suffers not only from subjectivity but also from the variable probability of corrosion detection, which is aggravated by the multiple layers used in fuselage construction. In this paper, we propose a methodology for automatic image-based corrosion detection of aircraft structures using deep neural networks. For machine learning, we use a dataset that consists of D-Sight Aircraft Inspection System (DAIS) images from different lap joints of Boeing and Airbus aircrafts. We also employ transfer learning to overcome the shortage of aircraft corrosion images. With precision of over 93%, we demonstrate that our approach detects corrosion with a precision comparable to that of trained operators, aiding to reduce the uncertainties related to operator fatigue or inadequate training. Our results indicate that our methodology can support specialists and engineers in corrosion monitoring in the aerospace industry, potentially contributing to the automation of condition-based maintenance protocols.


Assuntos
Aeronaves , Inteligência Artificial , Automação , Corrosão , Redes Neurais de Computação
7.
Talanta ; 233: 122565, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34215061

RESUMO

This work presents a new fast and sensitive method for voltammetric determination of Al(III) as Al(III)-cupferron complexes, which was used for the analysis of solution after exposure of aluminum alloy AA2024. Experimental conditions of voltammetric measurement such as preconcentration time, potential, and operating parameters were optimized. The formed Al(III)-cupferron complexes were adsorbed on an in situ plated lead film electrode (PbFE) using the potentials of -1.2 V (15 s) and -0.7 V (60 s) versus Ag/AgCl electrode. The promising results were obtained in 0.1 mol L-1 ammonia buffer at pH = 8.15 and 6 ∙ 10-5 mol L-1 Pb(II), 3 ∙ 10-4 mol L-1cupferron. The calibration graph was linear from 1 ∙ 10-10 to 2 ∙ 10-7 mol L-1 with the calculated detection limit of 3.3 ∙ 10-11 mol L-1, repeatability with RSD of 4.9% (n = 5). The accuracy was established by analysis of the synthetic sample.


Assuntos
Alumínio , Adsorção , Corrosão , Eletroquímica , Eletrodos
8.
Mater Sci Eng C Mater Biol Appl ; 127: 112239, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34225879

RESUMO

Biodegradable magnesium (Mg)-based vascular stents can overcome the limitations of conventional permanent metallic stents, such as late in-stent restenosis and thrombosis, but still have difficulty retarding degradation while providing adequate mechanical support to the blood vessel. We incorporated silica nanoparticles surface-functionalized with hexadecyltrimethoxysilane (mSiNP) into a poly (l-lactic acid) (PLLA) coating as a physical barrier to disturb the penetration of the corrosive medium as well as a bioactive source that releases silicon ions capable of stimulating endothelial cells. The corrosion resistance and biocompatibility of this bifunctional PLLA/mSiNP nanocomposite coating were investigated using different weight ratios of mSiNP. The nanocomposite coating containing more than 10 wt% of the mSiNP (PLLA/10mSiNP and PLLA/20mSiNP) significantly delayed the corrosion of the Mg substrate and exhibited favorable endothelial cell responses, compared to the pure PLLA coating. Specifically, the calculated corrosion rates of PLLA/10mSiNP and PLLA/20mSiNP decreased by half, indicating the durability of the coating after immersion in simulated body fluid for 12 days. Based on the in vitro cellular response, the incorporation of the mSiNPs into the PLLA coating significantly improved the endothelial cell responses to the Mg substrate, showing better initial cell surface coverage, migration, and proliferation rate than those of pure PLLA. These results indicate that the PLLA/mSiNP nanocomposite coatings have significant potential to improve the corrosion resistance and vascular compatibility of biodegradable Mg-based vascular stents.


Assuntos
Magnésio , Nanocompostos , Materiais Revestidos Biocompatíveis/farmacologia , Corrosão , Células Endoteliais , Ácido Láctico , Teste de Materiais , Poliésteres , Dióxido de Silício , Stents
9.
Molecules ; 26(12)2021 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-34208688

RESUMO

This study aimed to examine the extract of barks of Tamarix aphylla as a corrosion inhibitor. The methodology briefly includes plant sample collection, extraction of the corrosion inhibitor, gravimetric analysis, plotting potentiodynamic polarization plots, electrochemical impedance spectroscopic measurements, optimization of conditions, and preparation of the inhibitor products. The results show that the values of inhibition efficiency (IE%) increased as the concentrations of the inhibitor increased, with a maximum achievable inhibition efficiency of 85.0%. Potentiodynamic polarization (PP) tests revealed that the extract acts as a dual-type inhibitor. The results obtained from electrochemical impedance spectroscopy (EIS) measurements indicate an increase in polarisation resistance, confirming the inhibitive capacity of the tested inhibitor. The adsorption of the inhibitor on the steel surface follows the Langmuir adsorption isotherm model and involves competitive physio-sorption and chemisorption mechanisms. The EIS technique was utilized to investigate the effect of temperature on corrosion inhibition within the 298-328 K temperature range. Results confirm that the inhibition efficiency (IE%) of the inhibitor decreased slightly as the temperature increased. Lastly, the thermodynamic parameters for the inhibitor were calculated.


Assuntos
Aço/química , Tamaricaceae/química , Tamaricaceae/metabolismo , Carbono , Corrosão , Espectroscopia Dielétrica , Casca de Planta/química , Casca de Planta/metabolismo , Extratos Vegetais/química , Propriedades de Superfície , Termodinâmica
10.
Bone Joint J ; 103-B(7): 1238-1246, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34192940

RESUMO

AIMS: Dual mobility implants in total hip arthroplasty are designed to increase the functional head size, thus decreasing the potential for dislocation. Modular dual mobility (MDM) implants incorporate a metal liner (e.g. cobalt-chromium alloy) in a metal shell (e.g. titanium alloy), raising concern for mechanically assisted crevice corrosion at the modular liner-shell connection. We sought to examine fretting and corrosion on MDM liners, to analyze the corrosion products, and to examine histologically the periprosthetic tissues. METHODS: A total of 60 retrieved liners were subjectively scored for fretting and corrosion. The corrosion products from the three most severely corroded implants were removed from the implant surface, imaged using scanning electron microscopy, and analyzed using Fourier-transform infrared spectroscopy. RESULTS: Fretting was present on 88% (53/60) of the retrieved liners, and corrosion was present on 97% (58/60). Fretting was most often found on the lip of the taper at the transition between the lip and the dome regions. Macrophages and particles reflecting an innate inflammatory reaction to corrosion debris were noted in six of the 48 cases for which periprosthetic tissues were examined, and all were associated with retrieved components that had high corrosion scores. CONCLUSION: Our results show that corrosion occurs at the interface between MDM liners and shells and that it can be associated with reactions in the local tissues, suggesting continued concern that this problem may become clinically important with longer-term use of these implants. Cite this article: Bone Joint J 2021;103-B(7):1238-1246.


Assuntos
Ligas de Cromo/química , Prótese de Quadril , Desenho de Prótese , Titânio/química , Adulto , Idoso , Idoso de 80 Anos ou mais , Artroplastia de Quadril , Corrosão , Remoção de Dispositivo , Feminino , Humanos , Masculino , Microscopia Eletrônica de Varredura , Pessoa de Meia-Idade , Polietileno/química , Falha de Prótese , Reoperação , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de Superfície
11.
Molecules ; 26(11)2021 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-34205014

RESUMO

With the trend for green technology, the study focused on utilizing a forgotten herb to produce an eco-friendly coating. Andrographis paniculata or the kalmegh leaves extract (KLE) has been investigated for its abilities in retarding the corrosion process due to its excellent anti-oxidative and antimicrobial properties. Here, KLE was employed as a novel additive in coatings and formulations were made by varying its wt%: 0, 3, 6, 9, and 12. These were applied to stainless steel 316L immersed in seawater for up to 50 days. The samples were characterized and analyzed to measure effectiveness of inhibition of corrosion and microbial growth. The best concentration was revealed to be 6 wt% KLE; it exhibited the highest performance in improving the ionic resistance of the coating and reducing the growth of bacteria.


Assuntos
Andrographis/química , Materiais Revestidos Biocompatíveis/farmacologia , Extratos Vegetais/química , Água do Mar/química , Aço Inoxidável/farmacologia , Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Antioxidantes/química , Antioxidantes/farmacologia , Materiais Revestidos Biocompatíveis/química , Corrosão , Química Verde , Teste de Materiais , Folhas de Planta/química , Água do Mar/microbiologia , Aço Inoxidável/química
12.
Molecules ; 26(13)2021 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-34201553

RESUMO

The endoprosthetic care of hip and knee joints introduces multiple materials into the human body. Metal containing implant surfaces release degradation products such as particulate wear and corrosion debris, metal-protein complexes, free metallic ions, inorganic metal salts or oxides. Depending on the material composition of the prostheses, a systemic exposure occurs and may result in increasing metal concentrations in body fluids and tissues especially in the case of malfunctions of the arthroplasty components. High concentrations of Cr, Co, Ni, Ti and Al affect multiple organs such as thyroid, heart, lung and cranial nerves and may lead to metallosis, intoxications, poly-neuropathy, retinopathy, cardiomyopathy and the formation of localized pseudo tumors. The determination of the concentration of metals in body fluids and tissues can be used for predicting failure of hip or knee replacements to prevent subsequent severe intoxications. A semi-automated robot-assisted measurement system is presented for the determination of heavy metals in human tissue samples using inductively coupled plasma mass spectrometry (ICP-MS). The manual and automated measurement processes were similarly validated using certified reference material and the results are compared and discussed. The automation system was successfully applied in the determination of heavy metals in human tissue; the first results are presented.


Assuntos
Espectrometria de Massas/métodos , Metais Pesados/análise , Robótica/instrumentação , Robótica/métodos , Alumínio/análise , Autopsia , Cromo/análise , Cobalto/análise , Corrosão , Humanos , Íons/análise , Níquel/análise , Próteses e Implantes/efeitos adversos , Titânio/análise
13.
Molecules ; 26(11)2021 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-34198881

RESUMO

Euterpe oleracea Mart. (Arecaceae) is an endogenous palm tree from the Amazon region. Its seeds correspond to 85% of the fruit's weight, a primary solid residue generated from pulp production, the accumulation of which represents a potential source of pollution and environmental problems. As such, this work aimed to quantify and determine the phytochemical composition of E. oleracea Mart. seeds from purple, white, and BRS-Pará açaí varieties using established analytical methods and also to evaluate it as an eco-friendly corrosion inhibitor. The proanthocyanidin quantification (n-butanol/hydrochloric acid assay) between varieties was 6.4-22.4 (w/w)/dry matter. Extract characterization showed that all varieties are composed of B-type procyanidin with a high mean degree of polymerization (mDP ≥ 10) by different analytical methodologies to ensure the results. The purple açaí extract, which presented 22.4% (w/w) proanthocyanidins/dry matter, was tested against corrosion of carbon steel AISI 1020 in neutral pH. The crude extract (1.0 g/L) was effective in controlling corrosion on the metal surface for 24 h. Our results demonstrated that the extracts rich in polymeric procyanidins obtained from industrial açaí waste could be used to inhibit carbon steel AISI 1020 in neutral pH as an abundant, inexpensive, and green source of corrosion inhibitor.


Assuntos
Euterpe/química , Proantocianidinas/farmacologia , Aço/química , Corrosão , Química Verde , Extratos Vegetais/química , Proantocianidinas/química , Sementes/química
14.
Anal Chem ; 93(28): 9657-9662, 2021 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-34236831

RESUMO

Quantitative scanning micropipette contact method measurements are subject to the deleterious effects of reference electrode interference. The commonly used Ag/AgCl wire quasi-reference counter electrode in the miniaturized electrochemical cell of the scanning micropipette contact method was found to leak Ag+ into the electrolyte solution. The reduction of these Ag+ species at the working electrode surface generates a faradaic current, which significantly affects the low magnitude currents inherently measured in the scanning micropipette contact method. We demonstrate that, during the microscopic corrosion investigation of the AA7075-T73 alloy using the oil-immersed scanning micropipette contact method, the cathodic current was increased by the Ag+ reduction, resulting in positive shifts of corrosion potentials. The use of a leak-free Ag/AgCl electrode or an extended distance between the Ag/AgCl wire and micropipette tip droplet eliminated the Ag+ contamination, making it possible to measure accurate corrosion potentials during the oil-immersed scanning micropipette contact method measurements.


Assuntos
Ligas , Prata , Corrosão , Eletrodos
15.
Langmuir ; 37(31): 9439-9450, 2021 08 10.
Artigo em Inglês | MEDLINE | ID: mdl-34314588

RESUMO

Metal pipes in industrial production are exposed to various corrosive ions. The combined action of these ions with oxygen in water causes corrosion and contamination of the metal pipes and equipment. In addition, metallic ions in water react with anions to form scale on the surface of the metal, which significantly reduces the service life of the metal and equipment, resulting in safety hazards. Waterborne coatings have attracted tremendous attention due to the less negative impact on the environment, but their practical applications are severely restricted by poor barrier properties and poor mechanical durability. Herein, the barrier properties of water-based coatings are successfully improved by adding functional slow-release nanofillers, and the fillers also endow the coating with excellent antiscaling properties. A functional slow-release nanofiller (lecithin/SiO2/HEDP) was prepared using HEDP (etidronic acid) as the scale inhibitor active material and SiO2 as the carrier, combined with a phospholipid membrane with slow-release permeability. With the addition of slow-release fillers, compared with the EP coating, the impedance modulus of composite coatings increases about 1 order of magnitude, the scale inhibition rate is as high as 80.7%, and the antiscaling life is double that of the coating without the phospholipid-coated filler. Thus, this study is expected to provide a new perspective for the preparation of new slow-release fillers and high-efficiency scale inhibitor coatings.


Assuntos
Resinas Epóxi , Dióxido de Silício , Corrosão , Permeabilidade
16.
Acta Biomed ; 92(S3): e2021025, 2021 07 26.
Artigo em Inglês | MEDLINE | ID: mdl-34313658

RESUMO

BACKGROUND AND AIM OF THE WORK: Magnesium (Mg) is a metal physiologically present in bone tissue and essential for bone health. Mg-based-alloys exhibit mechanical properties, namely density and strength, similar to human cortical bone. These features have been exploited for the development of osteosynthesis devices in biodegradable Mg-based-alloys. Accordingly, the aim of this study was to rank the effectiveness and safety of Mg-based alloys applied in bone surgery in comparison to other suitable metals, focusing in particular on Mg superior biocompatibility and biodegradability. METHODS: a systematic-review of the literature was conducted including only primary research studies dealing with patients suffering from fractured or osteotomized bones fixed using Mg-based osteosynthesis-devices. RESULTS: literature revision suggested Mg-alloys holding comparable properties and side effects in comparison with titanium (Ti) screws, thus showing similar efficacy and safety. In particular, the gas formation in the carpal bones was identified as the main side effect of the Mg-alloys, during the corrosion/degradation phase of Mg. CONCLUSIONS: according to the considered literature, the main advantages exploiting Mg-alloys for bone implants are related to their biocompatibility, bio-absorbability/-degradability, the lack of surgical removal, osteoconductivity and antibacterial activity. On the opposite, the main limitation of Mg-alloys is due to the poor mechanical resistance of small devices for internal fixation of bone fragments that lack of sufficient strength to withstand high forces. Therefore, an important future prospect could rely in the development of innovative hybrid systems aimed at fixing high load-bearing fractures, as well as in regenerative-medicine by developing new Mg-based engineered scaffolds.


Assuntos
Ligas , Magnésio , Implantes Absorvíveis , Corrosão , Humanos , Titânio
17.
ACS Biomater Sci Eng ; 7(8): 3683-3695, 2021 08 09.
Artigo em Inglês | MEDLINE | ID: mdl-34291900

RESUMO

Ti6Al4V is one of the most lightweight, mechanically resistant, and appropriate for biologically induced corrosion alloys. However, surface properties often must be tuned for fitting into biomedical applications, and therefore, surface modification is of paramount importance to carry on its use. This work compares the interaction between two different cell lines (L929 fibroblasts and osteoblast-like MG63) and medical grade Ti6Al4V after surface modification by plasma nitriding or thin film deposition. We studied the adhesion of these two cell lines, exploring which trends are consistent for cell behavior, correlating with osseointegration and in vivo conditions. Modified surfaces were analyzed through several physicochemical characterization techniques. Plasma nitriding led to a more pronounced increase in surface roughness, a thicker aluminum-free layer, made up of diverse titanium nitride phases, whereas thin film deposition resulted in a single-phase pure titanium nitride layer that leveled the ridged topography. The selective adhesion of osteoblast-like cells over fibroblasts was observed in nitrided samples but not in thin film deposited films, indicating that the competitive cellular behavior is more pronounced in plasma nitrided surfaces. The obtained coatings presented an appropriate performance for its use in biomedical-aimed applications, including the possibility of a higher success rate in osseointegration of implants.


Assuntos
Materiais Revestidos Biocompatíveis , Estanho , Ligas , Corrosão , Propriedades de Superfície
18.
Molecules ; 26(12)2021 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-34207914

RESUMO

Extracts from plant materials have great potential as alternatives to inorganic corrosion inhibitors, which typically have harmful consequences. Experimental and theoretical methodologies studied the effectiveness of agricultural waste, namely, date palm seed extract as a green anti-corrosive agent in 0.5 M hydrochloric acid. Experimental results showed that immersion time and temperature are closely related to the effectivity of date palm seed as a corrosion inhibitor. The inhibition efficiency reduced from 95% to 91% at 1400 ppm when the immersion time was increased from 72 h to 168 h. The experimental results also indicated that the inhibition efficiency decreased as the temperature increased. The presence of a protective layer of organic matter was corroborated by scanning electron microscopy. The adsorption studies indicated that date palm seed obeyed Langmuir adsorption isotherm on the carbon steel surface, and Gibbs free energy values were in the range of -33.45 to -38.41 kJ·mol-1. These results suggested that the date palm seed molecules interacted with the carbon steel surface through mixture adsorption. Theoretical calculations using density functional theory showed that the capability to donate and accept electrons between the alloy surface and the date palm seed inhibitor molecules is critical for adsorption effectiveness. The HOMO and LUMO result indicated that the carboxyl (COOH) group and C=C bond were the most active sites for the electron donation-acceptance type of interaction and most auxiliary to the adsorption process over the Fe surface.


Assuntos
Carbono/química , Ácido Clorídrico/química , Phoeniceae/química , Extratos Vegetais/farmacologia , Sementes/química , Aço/química , Corrosão , Microscopia Eletrônica de Varredura/métodos , Modelos Teóricos , Extratos Vegetais/química , Temperatura
20.
Curr Microbiol ; 78(9): 3394-3402, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34232364

RESUMO

Salt water, in addition to being a naturally corrosive environment, also includes factors such as temperature, pressure, and the presence of the microbial community in the environment that influence degradation processes on metal surfaces. The presence or absence of water flow over the metal surfaces is also an important aspect that influences the corrosion of metals. The objective of this study was to evaluate the presence or absence of salt water flow in the formation of biofilms grown in 316L stainless steel coupons. For this, the 316L stainless steel coupons were exposed in two different microcosms, the first being a system with continuous salt water flow, and the second without salt water flow system. The results of the sequencing of the 16S rDNA genes showed a clear difference in structures and diversity between the evaluated biofilms. There was greater abundance and diversity in the "In Flux" system when compared to the "No Flux" biofilm. The analysis of bacterial diversity showed a predominance of the Gammaproteobacteria class in both systems. However, at lower taxonomic levels, there were considerable differences in representativeness. Representatives of Vibrionales, Alteromonadales, Oceanospirillales, and Flavobacteriales were predominant in "No Flux", whereas in "In Flux" there was a greater representation of Alteromonadales, Rhodobacterales, and Saprospirales. These findings help to understand how the flow of water influences the dynamics of the formation of microbial biofilms on metal surfaces, which will contribute to the choice of strategies used to mitigate microbial biofouling.


Assuntos
Microbiota , Aço Inoxidável , Biofilmes , Corrosão , Água
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