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1.
Bone Joint J ; 102-B(7_Supple_B): 116-121, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32600200

RESUMO

AIMS: This study aimed to determine if macrophages can attach and directly affect the oxide layers of 316L stainless steel, titanium alloy (Ti6Al4V), and cobalt-chromium-molybdenum alloy (CoCrMo) by releasing components of these alloys. METHODS: Murine peritoneal macrophages were cultured and placed on stainless steel, CoCrMo, and Ti6Al4V discs into a 96-well plate. Cells were activated with interferon gamma and lipopolysaccharide. Macrophages on stainless steel discs produced significantly more nitric oxide (NO) compared to their control counterparts after eight to ten days and remained elevated for the duration of the experiment. RESULTS: On stainless steel, both nonactivated and activated cell groups were shown to have a significant increase in metal ion release for Cr, Fe, and Ni (p < 0.001, p = 0.002, and p = 0.020 respectively) compared with medium only and showed macrophage-sized corrosive pits on the stainless steel surface. On titanium alloy discs there was a significant increase in aluminum (p < 0.001) among all groups compared with medium only. CONCLUSION: These results indicated that macrophages were able to attach to and affect the oxide surface of stainless steel and titanium alloy discs. Cite this article: Bone Joint J 2020;102-B(7 Supple B):116-121.


Assuntos
Prótese Articular , Macrófagos/química , Aço Inoxidável , Titânio , Vitálio , Ligas , Animais , Sobrevivência Celular , Cromo/análise , Meios de Cultura , Íons , Ferro/análise , Camundongos , Microscopia Eletrônica de Varredura , Níquel/análise , Óxido Nítrico/análise
2.
Chemosphere ; 257: 127182, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32534293

RESUMO

The impact of offshore constructions on the marine environment is unknown in many aspects. The application of Al- and Zn-based galvanic anodes as corrosion protection results in the continuous emission of inorganic matter (e.g. >80 kg Al-anode material per monopile foundation and year) into the marine environment. To identify tracers for emissions from offshore wind structures, anode materials (Al-based and Zn-based) were characterized for their elemental and isotopic composition. An acid digestion and analysis method for Al and Zn alloys was adapted and validated using the alloy CRMs ERM®-EB317 (AlZn6CuMgZr) and ERM®-EB602 (ZnAl4Cu1). Digests were measured for their elemental composition by ICP-MS/MS and for their Pb isotope ratios by MC ICP-MS. Ga and In were identified as potential tracers. Moreover, a combined tracer approach of the elements Al, Zn, Ga, Cd, In and Pb together with Pb isotope ratios is suggested for a reliable identification of offshore-wind-farm-induced emissions. In the Al anodes, the mass fractions were found to be >94.4% of Al, >26200 mg kg-1 of Zn, >78.5 mg kg-1 of Ga, >0.255 mg kg-1 of Cd, >143 mg kg-1 of In and >6.7 mg kg-1 of Pb. The Zn anodes showed mass fractions of >2160 mg kg-1 of Al, >94.5% of Zn, >1.31 mg kg-1 of Ga, >254 mg kg-1 of Cd, >0.019 mg kg-1 of In and >14.1 mg kg-1 of Pb. The n(208Pb)/n(206Pb) isotope ratios in Al anodes range from 2.0619 to 2.0723, whereas Zn anodes feature n(208Pb)/n(206Pb) isotope ratios ranging from 2.0927 to 2.1263.


Assuntos
Monitoramento Ambiental , Metais Pesados/análise , Poluentes Químicos da Água/análise , Ligas , Alumínio , Corrosão , Eletrodos , Isótopos/análise , Espectrometria de Massas em Tandem , Vento
3.
Khirurgiia (Mosk) ; (4): 61-64, 2020.
Artigo em Russo | MEDLINE | ID: mdl-32352670

RESUMO

A 93-year-old patient underwent endoscopic treatment of perforated duodenal ulcer after previous laparoscopic suturing complicated by failure of sutured defect. A self-expanding nitinol stent with partial polyurethane coating was used. Positive effect of the treatment was noted. Further study of this method and its clinical introduction in case of favorable results can significantly reduce the incidence of complications and mortality in patients with perforated gastroduodenal ulcers.


Assuntos
Úlcera Duodenal/cirurgia , Úlcera Péptica Perfurada/cirurgia , Idoso de 80 Anos ou mais , Ligas , Materiais Revestidos Biocompatíveis , Duodenoscopia , Gastroscopia , Humanos , Laparoscopia/efeitos adversos , Poliuretanos , Implantação de Prótese , Reoperação , Stents Metálicos Autoexpansíveis , Técnicas de Sutura/efeitos adversos
4.
J Contemp Dent Pract ; 21(1): 1, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32381792

RESUMO

Root canal treatment is one of the most challenging practices in dentistry as the complexity and the variability of the endodontic space can often lead the operator to create false trajectories or missing canals. The technical advances in the development of even more efficient and resistant endodontic instrument reached important results in the last few years with the adoption of NiTi alloys and thermal treatments, which could increase the flexibility and the resistance of the instruments.1,2.


Assuntos
Endodontia , Ligas , Ligas Dentárias , Assistência Odontológica , Humanos , Tratamento do Canal Radicular
5.
Cancer Radiother ; 24(2): 128-134, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32224107

RESUMO

PURPOSE: Shielding disks play an important role in intraoperative electron radiation therapy, and different designs are currently used in clinical practice. This paper investigates the dosimetric impact of the shielding disk used during intraoperative electron radiation therapy (IOERT). MATERIALS AND METHODS: This paper focuses on the study of four shielding disks types that have been used in our clinic: Aluminum (Al)/Lead (Pb), PMMA/Copper(Cu)/PMMA, Aluminum (Al)/Copper (Cu) and Aluminum (Al)/Steel with their specific thicknesses. The theoretical study was conducted with the EGSnrc Monte Carlo (MC) code. On the other hand, the measurements were carried out with gafchromic films for the four shielding disks for the same setup inside the water phantom. Finally, a comparison of the simulated and measured PDD curves was performed for the four material combinations. RESULTS: MC simulation and gafchromic measurements illustrated that dose values under the four shielding disks types were close to 0, whereas the backscattering enhancement of the disks were 103% with Al/Pb shielding disk, 102% with Al/Steel shielding disk, 102% with Al/Cu shielding disk, 95% with PMMA/Cu/PMMA shielding disk. The PDDs values of the gafchromic films in front of the disks were: 107%, 105%, 104%, and 94% for the Al/Pb, Al/Steel, Al/Cu, and PMMA/Cu/PMMA disks respectively. CONCLUSIONS: The dose values above and under the shielding disks were acceptable for the four studied shielding types. Demonstrated it is possible to use any of them clinically, while the best shielding disk was the Al/Pb since it has minimum thickness and a small backscatter enhancement.


Assuntos
Elétrons/uso terapêutico , Cuidados Intraoperatórios/instrumentação , Método de Monte Carlo , Órgãos em Risco , Proteção Radiológica/instrumentação , Ligas , Alumínio , Neoplasias da Mama/radioterapia , Cobre , Desenho de Equipamento , Feminino , Coração , Humanos , Cuidados Intraoperatórios/métodos , Pulmão , Aceleradores de Partículas , Imagens de Fantasmas , Dosagem Radioterapêutica , Costelas , Espalhamento de Radiação , Aço
6.
Environ Sci Pollut Res Int ; 27(18): 22639-22647, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32319060

RESUMO

The formation of highly graphitic phenolic resin chars (GPFCs) during catalytic carbonization at relatively low reaction temperature (1200-1600 °C) using novel Ni-Zn-B alloy catalyst with small amount of addition (5-15%) was systematically studied. Only two kinds of graphites (turbostratic graphite and ordered graphite) can be found in GPFCs after catalytic carbonization with Ni-Zn-B and their proportions were changed with reaction conditions. When Ni-Zn-B was involved at 1200-1600 °C, the phenolic resin char was fully transformed to be graphite, and ordered graphite content increased to 28.42% at 1400 °C, which was also almost twice of ordered graphite content in the char catalyzed by pure Ni. But the order graphite content would decrease due to sintering at higher reaction temperature. The addition of Zn and B can promote nickel-based alloy catalytic action by reducing melt point and accelerating graphitization respectively. It was also found that ordered graphite content could be used as a key evaluation parameter to directly reflect the quality of GPFCs based on detailed characteristics analysis. The model between three reaction conditions (reaction temperature, retention time, catalyst content) and ordered graphite content was built with artificial neural network (ANN), and the prediction accuracy of ANN was high up to 91.48%.


Assuntos
Grafite , Ligas , Formaldeído , Fenóis , Polímeros , Zinco
7.
PLoS One ; 15(4): e0231179, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32240256

RESUMO

Site-specific atom probe tomography (APT) from aluminum alloys has been limited by sample preparation issues. Indeed, Ga, which is conventionally used in focused-ion beam (FIB) preparations, has a high affinity for Al grain boundaries and causes their embrittlement. This leads to high concentrations of Ga at grain boundaries after specimen preparation, unreliable compositional analyses and low specimen yield. Here, to tackle this problem, we propose to use cryo-FIB for APT specimen preparation specifically from grain boundaries in a commercial Al-alloy. We demonstrate how this setup, easily implementable on conventional Ga-FIB instruments, is efficient to prevent Ga diffusion to grain boundaries. Specimens were prepared at room temperature and at cryogenic temperature (below approx. 90K) are compared, and we confirm that at room temperature, a compositional enrichment above 15 at.% of Ga is found at the grain boundary, whereas no enrichment could be detected for the cryo-prepared sample. We propose that this is due to the decrease of the diffusion rate of Ga at low temperature. The present results could have a high impact on the understanding of aluminum and Al-alloys.


Assuntos
Ligas/química , Alumínio/química , Tomografia/métodos , Gálio/química , Íons , Temperatura
8.
PLoS One ; 15(4): e0231276, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32275737

RESUMO

OBJECTIVES: Alloyed metallic nanoparticles of silver and copper are effective against intracellular infection. However, systemic toxicity may arise due to the non-specific delivery of the nanoparticles. In addressing the issue, this study deals with the targeting of silver-copper-boron (ACB) nanoparticles to infected osteoblasts, which could decrease systemic toxicity and form the basis of targeting specific markers expressed in bone infections. METHODS: ACB nanoparticles were synthesized and conjugated to the Cadherin-11 antibody (OBAb). The effect of targeting nanoparticles against extracellular and intracellular S. aureus was determined by enumeration of bacterial growth. The binding of the targeting nanoparticles to infected osteoblasts as well as the visualization of live/dead bacteria due to treatment was carried out using fluorescence microscopy. MTT assay was used to determine the viability of osteoblasts with different concentrations of the nanoparticles. RESULTS: The ACB nanoparticles conjugated to OBAb (ACB-OBAb) were effective against extracellular S. aureus. The ACB-OBAb nanoparticles showed a 1.32 log reduction of intracellular S. aureus at a concentration of 1mg/L. The ACB-OBAb nanoparticles were able to bind to the infected osteoblast and showed toxicity to osteoblasts at levels ≥20mg/L. Also, the percentage of silver, copper, and boron in the nanoparticles determined the effectiveness of their antibacterial activity. CONCLUSION: The ACB-OBAb nanoparticles were able to target the osteoblasts and demonstrated significant antibacterial activity against intracellular S. aureus. Targeting shows promise as a strategy to target specific markers expressed on infected osteoblasts for efficient nanoparticle delivery, and further animal studies are recommended to test its efficacy in vivo.


Assuntos
Ligas/farmacologia , Osso e Ossos/citologia , Boro/farmacologia , Cobre/farmacologia , Espaço Intracelular/microbiologia , Nanopartículas Metálicas/química , Prata/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Antibacterianos/farmacologia , Caderinas/imunologia , Linhagem Celular , Endocitose/efeitos dos fármacos , Humanos , Espaço Intracelular/efeitos dos fármacos , Nanopartículas Metálicas/ultraestrutura , Testes de Sensibilidade Microbiana , Osteoblastos/efeitos dos fármacos , Osteoblastos/microbiologia
10.
Nature ; 580(7802): 188-189, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32269348
11.
Comput Methods Biomech Biomed Engin ; 23(8): 372-383, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32116034

RESUMO

The aim of this study was to assess the stress/strain in dental implant/abutments with alternative materials, in implants with different microgeometry, through finite element analysis (FEA). Three-dimensional models were created to simulate the clinical situation of replacement of a maxillary central incisor with implants, in a type III bone, with a provisional single crown, loaded with 100 N in a perpendicular direction. The FEA parameters studied were: implant materials-titanium, porous titanium, titanium-zirconia, zirconia, reinforced fiberglass composite (RFC), and polyetheretherketone (PEEK); and abutment materials-titanium, zirconia, RFC, and PEEK; implant macrogeometry-tapered of trapezoidal threads (TTT) and cylindrical of triangular threads (CTT) (ø4.3 mm × 11 mm). Microstrain, von Mises, shear, and maximum and minimum principal stresses in the structures and in peri-implant bone were compared. There was increased stress and strain in peri-implant bone tissue caused by implants of materials with lower elastic modulus (mainly for PEEK and RFC). They also presented higher concentration of stresses in the implant itself (especially RFC). Zirconia implants led to lower stress and strains in peri-implant bone tissue. Less rigid abutments (RFC and PEEK) associated with titanium implants led to higher stress in the implant and in peri-implant bone tissue. The TTT macrogeometry showed a higher stress concentration in the implant and peri-implant bone tissue. The stress/strain in peri-implant bone tissue and implant structures were affected by the material used, where reduced values were caused by stiffer materials. Lower stress/strain values were obtained with cylindrical implants of triangular treads.


Assuntos
Ligas/química , Dente Suporte , Implantes Dentários , Análise do Estresse Dentário , Análise de Elementos Finitos , Dinâmica não Linear , Estresse Mecânico , Titânio/química , Humanos
12.
Zhonghua Yi Xue Za Zhi ; 100(7): 546-551, 2020 Feb 25.
Artigo em Chinês | MEDLINE | ID: mdl-32164109

RESUMO

Objective: To analyze the wear debris characteristics ofcarbon-based nano- multilayer coatings on Ti(6)Al(4)V alloys and compared with the cobalt chromium molybdenum alloy (CoCrMo) femoral head to evaluate the friction and wear performance of the new coated femoral head. Methods: Three groups were set up in the wear simulation experiment according to the type of femoral head. Group A: imported Cobalt-Chromium-Molybdenum alloy femoral head (CoCrMo); group B: Titanium alloy femoral head (Ti(6)Al(4)V) with carbon-based nano-multilayer coatings; group C: domestic Cobalt-Chromium-Molybdenum alloy femoral head (CoCrMo). All heads were jointed with an ultra-high molecular weight polyethylene (UHMWPE) acetabular cup. Serum samples were collected and stored in the hip joint simulator. After the sample has been digested and diluted, it was filtered through 5 µm, 1.2 µm and 0.4 µm filters, and the filter paper was collected for testing. Scanning electron microscope (SEM) was used to randomly select regions on the filter to obtain images of wear debris. Energy dispersive X-ray spectroscopy (EDS) was used to determine the elemental type of the particle and to eliminate possible contamination. The composition and structure of the abrasive chips were measured using Fourier transform infrared spectrometer (FTIR). The parameters related to the wear debris includingparticle size, shape, number and volume were calculated. The differences in correlation parameters between the groups were compared to evaluate the friction and wear properties of the new coated joints. Results: The main component of the wear debris produced was UHMWPE, and the particle size was mostly below 1 µm. The submicron particle ratio of group B was 49.4%, which was significantly lower than that of the group A and C (75% and 60%, respectively; χ(2)=66.032, 31.754, both P<0.017). The shape was mainly round, and there was no statistical difference between the groups (χ(2)=0.590, P=0.744). The number of particles in group B was significantly less than that of group C on all filters (t=9.960, 8.019, 5.790, all P<0.01), and less than group A on the 0.4 µm filter (t=7.810, P=0.000). Conclusion: The frictional wear performance of the new carbon-based nano-multilayer coatings femoral head is significantly better than that of the domestic femoral head, and even partially exceeds the imported femoral head level, which helps to reduce the production of particles and prevent osteolysis and aseptic loosening induced by UHMWPE particles.


Assuntos
Cabeça do Fêmur , Prótese de Quadril , Ligas , Carbono , Humanos , Teste de Materiais , Falha de Prótese , Titânio
13.
Expert Rev Med Devices ; 17(3): 167-171, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32073915

RESUMO

Introduction: This Wingspan Stent is a self-expanding, laser-cut, nitinol stent designed for the treatment of severe symptomatic intracranial artery stenosis to be used in conjunction with the Gateway angioplasty balloon. This review will describe the technical features of the stent, its composition, design, and functional characteristics, as well as an overview of its safety and efficacy.Areas covered: The engineering and manufacturing specifications are described for the stent. A systematic review of the literature from 2005 to 2019 is performed to define the safety profile of the stent as an implant for cerebral artery revascularization, stroke prophylaxis, and acute stroke treatment. These reports are compared to the published reports of patients with similar characteristics treated with medical therapy alone.Expert opinion: Although prior off-label studies have shown variable results, recent on-label studies have shown that the Wingspan stent itself is very safe, with low complication rates, and that it may confer long-term benefits in stroke prevention compared to medical therapy alone. Provided that established guidelines are followed, the Wingspan stent is effective in cerebral artery revascularization, and improves clinical outcomes in acute large vessel occlusive stroke with underlying intracranial atherosclerotic stenosis.


Assuntos
Arteriosclerose Intracraniana/cirurgia , Stents/efeitos adversos , Ligas , Ensaios Clínicos como Assunto , Humanos , Resultado do Tratamento
14.
PLoS One ; 15(2): e0228593, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32074123

RESUMO

The present investigation devices a novel X-type six-high (X-6h) mill. In addition, parametric models of different roll layouts such as the four-high (4-h), I-type six-high (I-6h), and X-6h mills are established. Three-dimensional (3D) finite element (FE) contact analysis for a strip rolling process is conducted when the mills are subjected to a constant vertical load of 65 kN. Through comparative analysis of von Mises stress, contact stress and elastic deformation displacement in three roll layouts, the rigidity characteristic of each is obtained, and it is found that the proposed X-6h mill has the largest roll gap stiffness. The influence of different roll diameter ratios on the roll gap stiffness of the roll system is investigated, based on which an optimization design model is built. Further, by taking into account the roll gap stiffness of the roll system as the optimization objective, the optimum diameter ratios of backup roll (BUR) to work roll (WR) of the X-6h rolling mill is achieved via the genetic algorithm (GA) optimization method, obtaining the optimum structural parameters of BUR and WR as well. The reliability of the proposed design is verified by manufacturing a prototype mill which produced magnesium alloy and aluminum alloy strips of high quality.


Assuntos
Indústria Manufatureira/instrumentação , Ciência dos Materiais/instrumentação , Aço/química , Ligas/química , Ligas/normas , Análise de Elementos Finitos , Magnésio/química , Indústria Manufatureira/métodos , Ciência dos Materiais/métodos , Fenômenos Mecânicos , Aço/normas
15.
Nat Commun ; 11(1): 1002, 2020 02 21.
Artigo em Inglês | MEDLINE | ID: mdl-32081910

RESUMO

Innovations in soft material synthesis and fabrication technologies have led to the development of integrated soft electronic devices. Such soft devices offer opportunities to interact with biological cells, mimicking their soft environment. However, existing fabrication technologies cannot create the submicron-scale, soft transducers needed for healthcare and medical applications involving single cells. This work presents a nanofabrication strategy to create submicron-scale, all-soft electronic devices based on eutectic gallium-indium alloy (EGaIn) using a hybrid method utilizing electron-beam lithography and soft lithography. The hybrid lithography process is applied to a biphasic structure, comprising a metallic adhesion layer coated with EGaIn, to create soft nano/microstructures embedded in elastomeric materials. Submicron-scale EGaIn thin-film patterning with feature sizes as small as 180 nm and 1 µm line spacing was achieved, resulting in the highest resolution EGaIn patterning technique to date. The resulting soft and stretchable EGaIn patterns offer a currently unrivaled combination of resolution, electrical conductivity, and electronic/wiring density.


Assuntos
Equipamentos e Provisões Elétricas , Eletrônica/instrumentação , Metais , Nanotecnologia/métodos , Ligas , Elastômeros , Condutividade Elétrica , Desenho de Equipamento , Gálio , Índio , Indústria Manufatureira/métodos , Impressão , Propriedades de Superfície
16.
Nat Biomed Eng ; 4(2): 142-143, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32051576
17.
J Cardiovasc Surg (Torino) ; 61(1): 84-92, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32079379

RESUMO

BACKGROUND: The aim of this study was to evaluate the safety and performance of the sinus-SuperFlex-635 self-expandable nitinol stent (Optimed GmbH) for the treatment of steno-occlusive lesions in the superficial femoral artery (SFA) and proximal popliteal artery (PPA). METHODS: The prospective, multicenter, observational HERO study recruited 117 eligible patients (83 men; mean age 69.4±9.7y) from 7 centers in Belgium. RESULTS: A total of 129 stents were successfully deployed in 121 lesions in 117 patients (100%). The patients presented with symptomatic ≥50% stenosis or chronic total occlusion (CTO) (30.6%). Mean lesion length was 71.4±56.3 mm. Moderate to severe calcification was present in 82.6% of the lesions. Acute lesion success (<30% residual stenosis) was achieved in 96.0%. There were no in-hospital serious adverse events. Duplex ultrasound-driven primary patency at 12 months was recorded in 84 of 107 (78.5%) lesions. The overall target lesion revascularization (TLR) rate was 8.4% at 12 months; the target extremity revascularization (TER) rate was 4.7%. Clinical assessment at 12 months demonstrated improvement by at least 1 Rutherford class, without the need for TLR (i.e. primary sustained clinical improvement) in 83.9% of patients and with the need for TLR in 90.6% of patients (i.e. secondary sustained clinical improvement). CONCLUSIONS: Based on the high primary patency, low stent fracture rate and significant clinical improvement, combined with refined stent design and long stent availability, the sinus-SuperFlex-635 self-expandable nitinol stent proves its value in the treatment of complex femoropopliteal lesions.


Assuntos
Procedimentos Endovasculares/instrumentação , Artéria Femoral , Doença Arterial Periférica/terapia , Artéria Poplítea , Stents Metálicos Autoexpansíveis , Calcificação Vascular/terapia , Idoso , Idoso de 80 Anos ou mais , Ligas , Bélgica , Procedimentos Endovasculares/efeitos adversos , Feminino , Artéria Femoral/diagnóstico por imagem , Artéria Femoral/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Doença Arterial Periférica/diagnóstico por imagem , Doença Arterial Periférica/fisiopatologia , Artéria Poplítea/diagnóstico por imagem , Artéria Poplítea/fisiopatologia , Estudos Prospectivos , Desenho de Prótese , Sistema de Registros , Fatores de Tempo , Resultado do Tratamento , Calcificação Vascular/diagnóstico por imagem , Calcificação Vascular/fisiopatologia , Grau de Desobstrução Vascular
18.
Artigo em Inglês | MEDLINE | ID: mdl-32032411

RESUMO

In order to obtain a more-natural esthetic prothesis, the use of hybrid abutments is becoming widespread in implant dentistry. The aim of this in vitro study was to assess the effects of different surface treatments, as well as the effects of different combinations of surface treatments and cementation protocols, on the shear bond strength between titanium alloy disks and lithium disilicate glass-ceramics. Forty titanium-alloy disks (4 × 6.6 mm) were fabricated using computer-aided designed/computer-assisted manufacturing, and an identical number of lithium disilicate glass-ceramic disks of similar sizes were fabricated by a heat-pressing technique to be attached to the titanium disks. The specimens from each material group were divided into two groups (n = 20 each) according to the surface treatment type: alumina airborne-particle abrasion or etching with hydrofluoric acid. Each group was then divided into two subgroups (n = 10) depending on the resin-cement type: Multilink Hybrid Abutment Cement (Ivoclar Vivadent) or PANAVIA SA Cement Plus (Kuraray). After thermocycling (5,000 cycles), a shear bond strength (SBS) test was conducted using a universal testing machine. Statistical analysis was performed by analysis of one-way analysis of variance and unpaired tests (P < .05). Statistically, the highest SBS values were obtained using airborne-particle abrasion. The surface treatment of titanium alloys by sandblasting led to a higher SBS compared to etching with hydrofluoric acid. The cement type also had a significant influence on SBS results.


Assuntos
Colagem Dentária , Titânio , Ligas , Cerâmica , Porcelana Dentária , Análise do Estresse Dentário , Teste de Materiais , Cimentos de Resina , Resistência ao Cisalhamento , Propriedades de Superfície
19.
PLoS One ; 15(2): e0229711, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32102092

RESUMO

PURPOSE: Real-time magnetic resonance imaging (MRI) is a promising alternative to X-ray fluoroscopy for guiding cardiovascular catheterization procedures. Major challenges, however, include the lack of guidewires that are compatible with the MRI environment, not susceptible to radiofrequency-induced heating, and reliably visualized. Preclinical evaluation of new guidewire designs has been conducted at 1.5T. Here we further evaluate the safety (device heating), device visualization, and procedural feasibility of 3T MRI-guided cardiovascular catheterization using a novel MRI-visible glass-fiber epoxy-based guidewire in phantoms and porcine models. METHODS: To evaluate device safety, guidewire tip heating (GTH) was measured in phantom experiments with different combinations of catheters and guidewires. In vivo cardiovascular catheterization procedures were performed in both healthy (N = 5) and infarcted (N = 5) porcine models under real-time 3T MRI guidance using a glass-fiber epoxy-based guidewire. The times for each procedural step were recorded separately. Guidewire visualization was assessed by measuring the dimensions of the guidewire-induced signal void and contrast-to-noise ratio (CNR) between the guidewire tip signal void and the blood signal in real-time gradient-echo MRI (specific absorption rate [SAR] = 0.04 W/kg). RESULTS: In the phantom experiments, GTH did not exceed 0.35°C when using the real-time gradient-echo sequence (SAR = 0.04 W/kg), demonstrating the safety of the glass-fiber epoxy-based guidewire at 3T. The catheter was successfully placed in the left ventricle (LV) under real-time MRI for all five healthy subjects and three out of five infarcted subjects. Signal void dimensions and CNR values showed consistent visualization of the glass-fiber epoxy-based guidewire in real-time MRI. The average time (minutes:seconds) for the catheterization procedure in all subjects was 4:32, although the procedure time varied depending on the subject's specific anatomy (standard deviation = 4:41). CONCLUSIONS: Real-time 3T MRI-guided cardiovascular catheterization using a new MRI-visible glass-fiber epoxy-based guidewire is feasible in terms of visualization and guidewire navigation, and safe in terms of radiofrequency-induced guidewire tip heating.


Assuntos
Cateterismo Cardíaco/métodos , Coração/diagnóstico por imagem , Imagem por Ressonância Magnética/métodos , Ligas , Animais , Cateteres Cardíacos , Sistema Cardiovascular , Resinas Epóxi , Desenho de Equipamento , Segurança de Equipamentos , Vidro , Modelos Animais , Imagens de Fantasmas , Suínos
20.
PLoS One ; 15(1): e0227259, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31968000

RESUMO

The paper discusses results of an interdisciplinary research project integrating lead isotope, chemical, and archaeological analysis of 20 early metal objects from central Italy. The aim of the research was to develop robust provenance hypotheses for 4th and 3rd millennia BC metals from an important, yet hitherto neglected, metallurgical district in prehistoric Europe, displaying precocious copper mining and smelting, as well as socially significant uses of metals in 'Rinaldone-style' burials. All major (and most minor) ore bodies from Tuscany and neighbouring regions were characterised chemically and isotopically, and 20 Copper Age axe-heads, daggers and halberds were sampled and analysed. The objects were also reassessed archaeologically, paying special attention to find context, typology, and chronology. This multi-pronged approach has allowed us to challenge received wisdom concerning the local character of early metal production and exchange in the region. The research has shown that most objects were likely manufactured in west-central Italy using copper from Southern Tuscany and, quite possibly, the Apuanian Alps. A few objects, however, display isotopic and chemical signatures compatible with the Western Alpine and, in one case, French ore deposits. This shows that the Copper Age communities of west-central Italy participated in superregional exchange networks tying together the middle/upper Tyrrhenian region, the western Alps, and perhaps the French Midi. These networks were largely independent from other metal displacement circuits in operation at the time, which embraced the north-Alpine region and the south-eastern Alps, respectively.


Assuntos
Arqueologia , Metalurgia/história , Mineração/história , Ligas/história , Sepultamento/história , Carvão Mineral/história , Cobre/história , Geografia , História Antiga , Isótopos/análise , Itália , Chumbo/análise
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