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1.
Carbohydr Polym ; 255: 117383, 2021 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-33436212

RESUMEN

Cellulose nanofibrils were efficiently produced from eucalyptus fibers using a combined NaOH and enzymatic treatment followed by a pilot scale grinding process. The structural changes of fibers were assessed after NaOH treatments at 5, 10 and 15 wt% concentrations. A progressive shift from a cellulose I to a cellulose II crystalline structure was observed with X-ray diffraction (XRD) and nuclear magnetic resonance (NMR). The further enzymatic hydrolysis was improved for the NaOH treated samples. The increase of crystallinity indices due to enzymatic hydrolysis was of + 4.7 %, + 3.5 %, and +10.3 % for samples treated with NaOH 5, 10 and 15 wt% respectively, and DP values were drastically reduced to 340, 190 and 166 respectively. A morphological analysis underlined an optimum with the combination of NaOH 10 wt% and enzymatic hydrolysis. This treatment followed by the grinding process resulted in CNF with a rigid structure, with diameters ranging from 10 to 20 nm and lengths between 150 and 350 nm. A multi-scale analysis enabled to study the impact of this combined treatment on CNF properties and energy consumption. A decrease in mechanical properties of nanopapers was observed for the combined treatment and NaOH treatment alone compared to enzymatic hydrolysis alone, with Young's modulus of 8.94, 4.84 and 11.21 GPa respectively. However, optical properties were improved, with transmittance values of 42.2, 15.4 and 7.1 % respectively. This new pretreatment can therefore lead to CNF with tunable properties depending on the application, with possible industrialization thanks to the reduction of energy needs.


Asunto(s)
Celulosa/química , Eucalyptus/química , Nanofibras/química , Hidróxido de Sodio/química , Biomasa , Cristalización , Módulo de Elasticidad , Hidrólisis , Ensayo de Materiales/métodos , Nanofibras/ultraestructura
2.
J Occup Environ Hyg ; 18(3): 128-138, 2021 03.
Artículo en Inglés | MEDLINE | ID: mdl-33476218

RESUMEN

The outbreak of the COVID-19 pandemic is causing a shortage of personal protective equipment (PPE) across the world. As a public health response to control the pandemic, wearing homemade face coverings has been proven as a resort to protect both the wearer and others from droplets and aerosols transmission. Although aerosols and droplets can be removed through these non-medical materials with a series of filtration mechanisms, their filtration performances have not been evaluated in detail. Moreover, many factors, such as the fabric properties and the method of usage, also affect filtration performance. In this study, the size-dependent filtration performances of non-medical materials as candidates for face coverings were evaluated comprehensively. The flow resistance across these filter materials, an indicator of breathability, was also examined. The effect of materials properties, washing and drying cycles, and triboelectric effect on particle filtration was also studied. Results showed that the filtration efficiency varied considerably from 5-50% among fabrics materials due to the material properties, such as density and microscopic structure of the materials. Microfiber cloth demonstrated the highest efficiency among the tested materials. In general, fabric materials with higher grams per square meter (GSM) show higher particle filtration efficiency. The results on washing and drying fabric materials indicated decent reusability for fabric materials. The triboelectric charge could increase the filtration performance of the tested fabric materials, but this effect diminishes soon due to the dissipation of charges, meaning that triboelectric charging may not be effective in manufacturing homemade face coverings.


Asunto(s)
/prevención & control , Filtración/instrumentación , Máscaras , Textiles , Ensayo de Materiales/métodos , Dispositivos de Protección Respiratoria
3.
Life Sci ; 270: 119126, 2021 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-33508295

RESUMEN

AIMS: To investigate the biomimetic fabrication of fibrous-like organic-inorganic hybrid structures via a simple bottom-up approach, viz. self-assembly of simple molecules, and apply fibrous-like composites as a novel primer to improve dentin bond strengths of self-etch adhesives. MATERIALS AND METHODS: The resultants of commercial amorphous calcium phosphate (ACP) nanoparticles and 10-methacryloyloxydecyl dihydrogen phosphate (MDP) ethanol-aqueous solution were analyzed by TEM, SEM, XRD, DLS and AFM. The acid and alkali resistance of abovementioned self-assembled composites were analyzed with TEM. Micro-tensile bond strengths (MTBS) tests were performed after polished dentin surfaces were pretreated with self-assembled composites. The pretreated dentin surfaces and dentin-resin interfaces were characterized by SEM/TEM. KEY FINDINGS: ACP nanoparticles in MDP solution could self-assemble into fibrous-like nanotube structures in 8 nm diameter. Self-assembly and self-proliferation process went from ACP nanoparticles, dissolved ACP nanoparticles (less than 50 nm), twig-like structures and fibrous-like nanotubes to cellular networks. The fibrous-like nanotubes were only detected when the amount of ACP in reaction system were more than 0.01 g. The more ACP interacted with MDP, the more fibrous-like nanotubes were formed. After the dentin surfaces were treated with fibrous-like nanotube composites, MTBS could be significantly improved. Moreover, the fibrous-like nanotube structures could be resistant to acidic challenge, and were stable at least for 3 months. SIGNIFICANCE: The fibrous-like nanotube structures could be self-assembled via a bottom-up approach at certain ratio of MDP and commercial ACP nanoparticles. The application of fibrous-like nanotube composites as a novel primer prior to self-etch adhesives greatly improved dentin bond strengths.


Asunto(s)
Biomimética/métodos , Dentina/química , Nanotubos/química , Adhesivos/química , Fosfatos de Calcio/química , Humanos , Ensayo de Materiales/métodos , Metacrilatos/química , Nanopartículas/química , Resistencia a la Tracción/fisiología
4.
S Afr Med J ; 0(0): 13162, 2020 12 09.
Artículo en Inglés | MEDLINE | ID: mdl-33334390

RESUMEN

BACKGROUND: Given the global shortage of N95 filtering facepiece respirators (FFP2 in Europe) during the COVID-19 pandemic, KN95 masks (Chinese equivalent of the N95 and FFP2) were imported and distributed in South Africa (SA). However, there are hardly any published independent safety data on KN95 masks. OBJECTIVES: To evaluate the seal, fit and filtration efficiency of several brands of KN95 masks marketed for widespread use in SA healthcare facilities, using standardised testing protocols. METHODS: The verifiability of manufacturer and technical details was first ascertained, followed by evaluation of the number of layers comprising the mask material. The testing protocol involved a directly observed positive and negative pressure user seal check, which if passed was followed by qualitative fit testing (sodium saccharin) in healthy laboratory or healthcare workers. Quantitative fit testing (3M) was used to validate the qualitative fit testing method. The filtration efficacy and integrity of the mask filter material were evaluated using a particle counter-based testing rig utilising aerosolised saline (expressed as filtration efficacy of 0.3 µm particles). Halyard FLUIDSHIELD 3 N95 and 3M 1860 N95 masks were used as controls. RESULTS: Twelve KN95 mask brands (total of 36 masks) were evaluated in 7 participants. The mask type and manufacturing details were printed on only 2/12 brands (17%) as per National Institute of Occupational Safety and Health and European Union regulatory requirements. There was considerable variability in the number of KN95 mask layers (between 3 and 6 layers in the 12 brands evaluated). The seal check pass rate was significantly lower in KN95 compared with N95 masks (1/36 (3%) v. 12/12 (100%); p<0.0001). Modification of the KN95 ear-loop tension using head straps or staples, or improving the facial seal using Micropore 3M tape, enhanced seal test performance in 15/36 KN95 masks evaluated (42%). However, none of these 15 passed downstream qualitative fit testing compared with the control N95 masks (0/15 v. 12/12; p<0.0001). Only 4/8 (50%) of the KN95 brands tested passed the minimum filtration requirements for an N95 mask (suboptimal KN95 filtration efficacy varied from 12% to 78%, compared with 56% for a surgical mask and >99% for the N95 masks at the 0.3 µm particle size). CONCLUSIONS: The KN95 masks tested failed the stipulated safety thresholds associated with protection of healthcare workers against airborne pathogens such as SARS-CoV-2. These preliminary data have implications for the regulation of masks and their distribution to healthcare workers and facilities in SA.


Asunto(s)
Transmisión de Enfermedad Infecciosa de Paciente a Profesional/prevención & control , Ensayo de Materiales/métodos , Exposición Profesional/prevención & control , /epidemiología , Diseño de Equipo/métodos , Diseño de Equipo/normas , Análisis de Falla de Equipo , Humanos , Administración de la Seguridad/organización & administración , Sudáfrica/epidemiología
5.
PLoS One ; 15(12): e0244463, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33373392

RESUMEN

Advances in additive manufacturing enable the production of tailored lattice structures and thus, in principle, coronary stents. This study investigates the effects of process-related irregularities, heat and surface treatment on the morphology, mechanical response, and expansion behavior of 316L stainless steel stents produced by laser powder bed fusion and provides a methodological approach for their numerical evaluation. A combined experimental and computational framework is used, based on both actual and computationally reconstructed laser powder bed fused stents. Process-related morphological deviations between the as-designed and actual laser powder bed fused stents were observed, resulting in a diameter increase by a factor of 2-2.6 for the stents without surface treatment and 1.3-2 for the electropolished stent compared to the as-designed stent. Thus, due to the increased geometrically induced stiffness, the laser powder bed fused stents in the as-built (7.11 ± 0.63 N) or the heat treated condition (5.87 ± 0.49 N) showed increased radial forces when compressed between two plates. After electropolishing, the heat treated stents exhibited radial forces (2.38 ± 0.23 N) comparable to conventional metallic stents. The laser powder bed fused stents were further affected by the size effect, resulting in a reduced yield strength by 41% in the as-built and by 59% in the heat treated condition compared to the bulk material obtained from tensile tests. The presented numerical approach was successful in predicting the macroscopic mechanical response of the stents under compression. During deformation, increased stiffness and local stress concentration were observed within the laser powder bed fused stents. Subsequent numerical expansion analysis of the derived stent models within a previously verified numerical model of stent expansion showed that electropolished and heat treated laser powder bed fused stents can exhibit comparable expansion behavior to conventional stents. The findings from this work motivate future experimental/numerical studies to quantify threshold values of critical geometric irregularities, which could be used to establish design guidelines for laser powder bed fused stents/lattice structures.


Asunto(s)
Diseño Asistido por Computadora , Diseño de Equipo/métodos , Ensayo de Materiales/métodos , Stents Metálicos Autoexpandibles , Acero Inoxidable/química , Enfermedad Coronaria/cirugía , Procedimientos Endovasculares/instrumentación , Análisis de Elementos Finitos , Humanos , Estrés Mecánico
6.
PLoS One ; 15(10): e0240499, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33048980

RESUMEN

During the current SARS-CoV-2 pandemic there is unprecedented demand for personal protective equipment (PPE), especially N95 respirators and surgical masks. The ability of SARS-CoV-2 to be transmitted via respiratory droplets from asymptomatic individuals has necessitated increased usage of both N95 respirators in the healthcare setting and masks (both surgical and homemade) in public spaces. These precautions rely on two fundamental principles of transmission prevention: particle filtration and droplet containment. The former is the focus of NIOSH N95 testing guidelines, and the latter is an FDA guideline for respirators and surgical masks. While studies have investigated droplet containment to provide guidance for homemade mask production, limited work has been done to characterize the filtration efficiency (FE) of materials used in home mask making. In this work, we demonstrate the low-cost (<$300) conversion of standard equipment used to fit-test respirators in hospital and industrial settings into a setup that measures quantitative FEs of materials based on NIOSH N95 guidelines, and subsequently measure FEs of materials found in healthcare and consumer spaces. These materials demonstrate significant variability in filtration characteristics, even for visually similar materials. We demonstrate a FE of 96.49% and pressure drop of 25.4 mmH20 for a double-layer of sterilization wrap used in surgical suites and a FE of 90.37% for a combination of consumer-grade materials. The excellent filtration characteristics of the former demonstrate potential utility for emergent situations when N95 respirators are not available, while those of the latter demonstrate that a high FE can be achieved using publicly available materials.


Asunto(s)
Filtros de Aire/normas , Betacoronavirus , Infecciones por Coronavirus/prevención & control , Seguridad de Equipos/métodos , Máscaras/normas , Ensayo de Materiales/métodos , Pandemias/prevención & control , Equipo de Protección Personal/normas , Neumonía Viral/prevención & control , Dispositivos de Protección Respiratoria/normas , Aerosoles , Infecciones por Coronavirus/virología , Seguridad de Equipos/instrumentación , Personal de Salud , Humanos , Ensayo de Materiales/instrumentación , Exposición Profesional/prevención & control , Neumonía Viral/virología
7.
J Vis Exp ; (162)2020 08 21.
Artículo en Inglés | MEDLINE | ID: mdl-32894265

RESUMEN

In this study, the hemocompatibility of tubes with an inner diameter of 5 mm made of polyvinyl chloride (PVC) and coated with different bioactive conjugates was compared to uncoated PVC tubes, latex tubes, and a stent for intravascular application that was placed inside the PVC tubes. Evaluation of hemocompatibility was done using an in vitro hemodynamic loop model that is recommended by the ISO standard 10993-4. The tubes were cut into segments of identical length and closed to form loops avoiding any gap at the splice, then filled with human blood and rotated in a water bath at 37 °C for 3 hours. Thereafter, the blood inside the tubes was collected for the analysis of whole blood cell count, hemolysis (free plasma hemoglobin), complement system (sC5b-9), coagulation system (fibrinopeptide A), and leukocyte activation (polymorphonuclear elastase, tumor necrosis factor and interleukin-6). Host cell activation was determined for platelet activation, leukocyte integrin status and monocyte platelet aggregates using flow cytometry. The effect of inaccurate loop closure was examined with x-ray microtomography and scanning electron microscopy, that showed thrombus formation at the splice. Latex tubes showed the strongest activation of both plasma and cellular components of the blood, indicating a poor hemocompatibility, followed by the stent group and uncoated PVC tubes. The coated PVC tubes did not show a significant decrease in platelet activation status, but showed an increased in complement and coagulation cascade compared to uncoated PVC tubes. The loop model itself did not lead to the activation of cells or soluble factors, and the hemolysis level was low. Therefore, the presented in vitro hemodynamic loop model avoids excessive activation of blood components by mechanical forces and serves as a method to investigate in vitro interactions between donor blood and vascular medical devices.


Asunto(s)
Células Sanguíneas/metabolismo , Prótesis Vascular , Materiales Biocompatibles Revestidos/química , Hemodinámica/fisiología , Ensayo de Materiales/métodos , Células Sanguíneas/citología , Coagulación Sanguínea , Proteínas del Sistema Complemento/metabolismo , Humanos , Ensayo de Materiales/normas , Modelos Biológicos , Plasma/metabolismo , Activación Plaquetaria , Cloruro de Polivinilo/química
9.
Niger J Clin Pract ; 23(8): 1068-1072, 2020 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-32788483

RESUMEN

Aims: The aim of this study was to compare the influence of operators on the microhardness and compressive strength of mineral trioxide aggregate (MTA). Materials and Methods: Forty dental specialists were asked to prepare a series of MTA samples. The tested material was ProRoot MTA (DentsplyMaillefer, Switzerland). Each participant prepared one sample to a consistency they considered acceptable for use in practice (improvised group) and another one according to the manufacturer's recommended water-to-powder (WP) ratio (pre-weighed group). The samples were incubated at 37°C and 95% humidity for 4 days. Parameters evaluated in this study were microhardness and compressive strength. Results: Operators mixed MTA samples with varying WP ratios. However, there was no significant difference between the microhardness and compressive strength values of MTA samples between the improvised, the pre-weighed and the control groups. MTA was mixed in a thicker consistency than the manufacturers recommended ratio (0.33) by 62.5% of the operators. Conclusion: According to the results of this study, even though the WP ratios that were utilized in the clinical setting vary, microhardness and compressive strength values of MTA was not significantly affected.


Asunto(s)
Compuestos de Aluminio/química , Compuestos de Calcio/química , Fuerza Compresiva , Ensayo de Materiales/métodos , Óxidos/química , Materiales de Obturación del Conducto Radicular , Silicatos/química , Estudios de Casos y Controles , Combinación de Medicamentos , Dureza , Humanos , Agua
10.
Niger J Clin Pract ; 23(8): 1148-1154, 2020 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-32788494

RESUMEN

Aims: The effect of mechanical loading on the microtensile bond strength (µTBS) of universal adhesives to dentin was evaluated in this study. Methods and Materials: Human molar teeth had the occlusal dentin surfaces exposed and were allocated into ten groups (five experimental groups and five control groups) that used the following universal adhesive systems in self-etch mode: All-Bond Universal (ABU), Single Bond Universal (SBU), Gluma Bond Universal (GBU), Tetric N-Bond Universal (TBU), and Clearfil Universal Bond (CUB). Following the bonding procedures and build-ups, the specimens were either stored in water at 37°C for 24 h or were mechanically loaded (50 N for 60,000 cycles) prior to the µTBS test. Data were analyzed using the one-way analysis of variance (ANOVA) and Tukey's posthoc test (P = 0.05). Results: Both the adhesive type and mechanical loading had significant effects on the µTBS (P < 0.05). The µTBS values of SBU and ABU were significantly higher than the values of the other adhesives (P < 0.05). However, the µTBS values of ABU decreased significantly after mechanical loading (P < 0.05). Conclusions: With the exception of ABU, mechanical loading had no deleterious effects on the µTBS of the universal adhesive systems examined in this study.


Asunto(s)
Adhesivos/química , Recubrimiento Dental Adhesivo/métodos , Recubrimientos Dentinarios/química , Bisfenol A Glicidil Metacrilato , Resinas Compuestas , Glutaral , Humanos , Ensayo de Materiales/métodos , Diente Molar , Ácidos Polimetacrílicos , Cementos de Resina/química , Resistencia a la Tracción
11.
Int J Infect Dis ; 99: 505-513, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-32861829

RESUMEN

OBJECTIVES: Face masks are an important component of personal protection equipment employed in preventing the spread of diseases such as COVID-19. As the supply of mass-produced masks has decreased, the use of homemade masks has become more prevalent. It is important to quantify the effectiveness of different types of materials to provide useful information, which should be considered for homemade masks. METHODS: Filtration effects of different types of common materials were studied by measuring the aerosol droplet concentrations in the upstream and downstream regions. Flow-field characteristics of surrounding regions of tested materials were investigated using a laser-diagnostics technique, i.e., particle image velocimetry. The pressure difference across the tested materials was measured. RESULTS: Measured aerosol concentrations indicated a breakup of large-size particles into smaller particles. Tested materials had higher filtration efficiency for large particles. Single-layer materials were less efficient, but they had a low pressure-drop. Multilayer materials could produce greater filtering efficiency with an increased pressure drop, which is an indicator of comfort level and breathability. The obtained flow-fields indicated a flow disruption downstream of the tested materials as the velocity magnitude noticeably decreased. CONCLUSIONS: The obtained results provide an insight into flow-field characteristics and filtration efficiency of different types of household materials commonly used for homemade masks. This study allows comparison with mass-produced masks under consistent test conditions while employing several well-established techniques.


Asunto(s)
Infecciones por Coronavirus/prevención & control , Filtración , Máscaras , Ensayo de Materiales , Pandemias/prevención & control , Neumonía Viral/prevención & control , Textiles , Aerosoles , Betacoronavirus , Filtración/instrumentación , Humanos , Ensayo de Materiales/métodos , Tamaño de la Partícula
12.
J Interv Cardiol ; 2020: 8413831, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32665769

RESUMEN

Aims: To investigate the healing process and nickel release of the Hyperion occluder (Comed BV, Netherlands), as compared to the Amplatzer septal occluder (ASO) (St. Jude Medical Inc., St. Paul, MN, USA) in a chronic swine model. Background: Some long-term complications occurring after percutaneous atrial septal defect (ASD) closure may be partially associated with an inappropriate healing of the device and increased nickel release. There is no direct comparative study of different occluders for healing and nickel release. Methods: After percutaneous ASD creation, 12 pigs were implanted with 15 mm Hyperion (n = 6) and 15 mm ASO (n = 6) devices. After 1 month (n = 3 for each device) and 3 months (n = 3 for each device) of follow-up, device explantation was performed and healing was assessed using histopathological workup. Systemic and tissular nickel release was performed. Results: Implantation was successful in 100% without complications. Device coverage was observed as early as 1 month after implantation and was almost complete after 3 months. A granulation tissue with a predominantly mononuclear inflammatory reaction was observed in contact with nitinol wires while an inflammatory reaction was seen in contact with textile fibers. We found no statistically significant difference between the 2 devices whether for histological grading scores or systemic nickel release, regardless to follow-up duration. Conclusions: In this preclinical study, we demonstrated that Amplatzer septal occluder and Hyperion occluder were not significantly different for device healing and nickel release processes.


Asunto(s)
Aleaciones/farmacología , Defectos del Tabique Interatrial/cirugía , Efectos Adversos a Largo Plazo/inducido químicamente , Ensayo de Materiales/métodos , Complicaciones Posoperatorias/inducido químicamente , Implantación de Prótesis , Dispositivo Oclusor Septal/efectos adversos , Aleaciones/efectos adversos , Animales , Investigación sobre la Eficacia Comparativa , Efectos Adversos a Largo Plazo/prevención & control , Níquel/efectos adversos , Níquel/farmacología , Evaluación de Resultado en la Atención de Salud , Complicaciones Posoperatorias/prevención & control , Diseño de Prótesis , Implantación de Prótesis/efectos adversos , Implantación de Prótesis/instrumentación , Porcinos , Oligoelementos/efectos adversos , Oligoelementos/farmacología , Resultado del Tratamiento
13.
PLoS One ; 15(7): e0234851, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32609741

RESUMEN

A lack of N95 Filtering Facepiece Respirators (FFRs) during the COVID-19 crisis has placed healthcare workers at risk. It is important for any N95 reuse strategy to determine the effects that proposed protocols would have on the physical functioning of the mask, as well as the practical aspects of implementation. Here we propose and implement a method of heating N95 respirators with moisture (85°C, 60-85% humidity). We test both mask filtration efficiency and fit to validate this process. Our tests focus on the 3M 1860, 3M 1870, and 3M 8210 Plus N95 models. After five cycles of the heating procedure, all three respirators pass both quantitative fit testing (score of >100) and show no degradation of mask filtration efficiency. We also test the Chen Heng V9501 KN95 and HKYQ N95 finding no degradation of mask filtration efficiency, however even for unheated masks these scored <50 for every fit test. The heating method presented here is scalable from individual masks to over a thousand a day with a single industrial convection oven, making this method practical for local application inside health-care facilities.


Asunto(s)
Betacoronavirus , Infecciones por Coronavirus/epidemiología , Descontaminación/métodos , Equipo Reutilizado , Calefacción/métodos , Humedad , Máscaras/virología , Neumonía Viral/epidemiología , Dispositivos de Protección Respiratoria/virología , Infecciones por Coronavirus/virología , Filtración/instrumentación , Humanos , Ensayo de Materiales/métodos , Exposición Profesional/prevención & control , Pandemias , Neumonía Viral/virología
14.
PLoS One ; 15(6): e0235168, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32579611

RESUMEN

OBJECTIVE: There is an increasing need for small diameter vascular grafts with superior host hemo- and cytocompatibilities, such as low activation of platelets and leukocytes. Therefore, we aimed to investigate whether the preparation of bacterial nanocellulose grafts with different inner surfaces has an impact on in vitro host cytocompatibility. METHODS: We have synthesized five different grafts in a bioreactor, namely open interface surface (OIS), inverted (INV), partially air dried (PAD), surface formed in air contact (SAC) and standard (STD) that were characterized by a different surface roughness. The grafts (length 55 mm, inner diameter 5 mm) were attached to heparinized polyvinyl chloride tubes, loaded with human blood and rotated at 37°C for 4 hours. Then, blood was analyzed for frequencies of cellular fractions, oxidative products, soluble complement and thrombin factors. The results were compared to clinically approved grafts made of polyethylene terephthalate and expanded polytetrafluoroethylene. Additionally, blood platelets were labelled with 111Indium-oxine to visualize the distribution of adherent platelets in the loop by scintigraphy. RESULTS: SAC nanocellulose grafts with the lowest surface roughness exhibited superior performance with <10% leukocyte and <50% thrombocyte loss in contrast to other grafts that exhibited >65% leukocyte and >90% thrombocyte loss. Of note, SAC nanocellulose grafts showed lowest radioactivity with scintigraphy analyses, indicating reduced platelet adhesion. Although the levels of reactive oxygen species and cell free DNA did not differ significantly, the levels of thrombin-antithrombin complexes were lowest in SAC grafts. However, all nanocellulose grafts exhibited enhanced complement activation. CONCLUSION: The systematic variation of the inner surfaces of BNC vascular grafts significantly improves biocompatibility. Especially, SAC grafts exhibited the lowest loss of platelets as well as leukocytes and additionally significantly diminished activation of the coagulation system. Further animal studies are needed to study in vivo biocompatibilities.


Asunto(s)
Materiales Biocompatibles/química , Prótesis Vascular , Celulosa/química , Polisacáridos Bacterianos/química , Grado de Desobstrucción Vascular/fisiología , Animales , Coagulación Sanguínea/efectos de los fármacos , Implantación de Prótesis Vascular/métodos , Celulosa/ultraestructura , Oclusión de Injerto Vascular/fisiopatología , Oclusión de Injerto Vascular/prevención & control , Heparina/farmacología , Humanos , Ensayo de Materiales/métodos , Microscopía Electrónica de Rastreo , Adhesividad Plaquetaria/fisiología , Tereftalatos Polietilenos/química , Politetrafluoroetileno/química , Propiedades de Superficie , Grado de Desobstrucción Vascular/efectos de los fármacos
15.
Jt Dis Relat Surg ; 31(2): 328-334, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32584733

RESUMEN

OBJECTIVES: This study aims to investigate the biocompatibility and cytotoxicity of daptomycin, gentamicin, vancomycin and teicoplanin at commonly-used dose intervals added to polymethylmethacrylate (PMMA) in vitro. MATERIALS AND METHODS: This prospective study was conducted between February 2016 and June 2016. Antibiotics were added to PMMA at doses frequently used in clinical practice. The antibiotic doses added were teicoplanin (2 g, 3 g, 4 g), gentamicin (0.5 g, 0.75 g, 1 g), daptomycin (0.5 g.) and vancomycin (2 g, 3 g, 4 g). Standard cement balls (10 mm) were created. Activated L929 mouse fibroblast cell culture was used for incubation. Agar diffusion, Cell Proliferation Kit II (XTT) test and electron microscope investigations were performed to examine biocompatibility and cytotoxicity. RESULTS: In the cytotoxicity test, teicoplanin at 4 g and daptomycin at 0.5 g doses were observed to cause reductions in viability percentages. The same doses caused 20% and 20-40% cell lysis indices during the agar diffusion test. On electron microscope images, cytotoxic effects in fibroblast cells and involvement with the surface of cement balls were observed. CONCLUSION: Gentamicin, vancomycin and teicoplanin were observed to be non-toxic and biocompatible at commonly-used dose intervals. Teicoplanin at 4 g and daptomycin at 0.5 g doses were identified to be cytotoxic and not biocompatible. When selecting antibiotics to be added to bone cement, care should be taken that the antibiotic is non-toxic and biocompatible.


Asunto(s)
Cementos para Huesos/farmacología , Daptomicina/farmacología , Gentamicinas/farmacología , Teicoplanina/farmacología , Vancomicina/farmacología , Animales , Antibacterianos/farmacología , Células Cultivadas , Pruebas Inmunológicas de Citotoxicidad/métodos , Relación Dosis-Respuesta a Droga , Ensayo de Materiales/métodos , Ratones , Materiales de Enseñanza
16.
Sci Rep ; 10(1): 9456, 2020 06 11.
Artículo en Inglés | MEDLINE | ID: mdl-32528137

RESUMEN

A silicalite-1 film (SF) deposited on Ti-6Al-4V alloy was investigated in this study as a promising coating for metallic implants. Two forms of SFs were prepared: as-synthesized SFs (SF-RT), and SFs heated up to 500 °C (SF-500) to remove the excess of template species from the SF surface. The SFs were characterized in detail by X-ray photoelectron spectroscopy (XPS), by Fourier transform infrared spectroscopy (FTIR), by scanning electron microscopy (SEM) and water contact angle measurements (WCA). Two types of bone-derived cells (hFOB 1.19 non-tumor fetal osteoblast cell line and U-2 OS osteosarcoma cell line) were used for a biocompatibility assessment. The initial adhesion of hFOB 1.19 cells, evaluated by cell numbers and cell spreading area, was better supported by SF-500 than by SF-RT. While no increase in cell membrane damage, in ROS generation and in TNF-alpha secretion of bone-derived cells grown on both SFs was found, gamma H2AX staining revealed an elevated DNA damage response of U-2 OS cells grown on heat-treated samples (SF-500). This study also discusses differences between osteosarcoma cell lines and non-tumor osteoblastic cells, stressing the importance of choosing the right cell type model.


Asunto(s)
Citotoxinas/farmacología , Osteoblastos/efectos de los fármacos , Osteocitos/efectos de los fármacos , Titanio/química , Materiales Biocompatibles/química , Línea Celular , Línea Celular Tumoral , Membrana Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Citotoxinas/química , Calor , Humanos , Ensayo de Materiales/métodos , Microscopía Electrónica de Rastreo/métodos , Espectroscopía de Fotoelectrones/métodos , Propiedades de Superficie/efectos de los fármacos
17.
Acta Orthop Traumatol Turc ; 54(3): 293-299, 2020 May.
Artículo en Inglés | MEDLINE | ID: mdl-32544065

RESUMEN

OBJECTIVE: The aim of this study was to evaluate the clinical outcomes and the coronal correction rate of the main and accompanying curves of adolescent idiopathic scoliosis (AIS) corrected with pedicle screws inserted consecutively or intermittently. METHODS: The prospectively collected data of 60 patients (8 men and 52 women; mean age: 14.6±2.5 years) who underwent corrective surgery for AIS between January 2010 and December 2015 were reviewed retrospectively. Two groups were constituted according to the pedicle screw construct type: consecutive pedicle screw construct (CPSC) and intermittent pedicle screw construct (IPSC) groups. The preoperative, early postoperative, and 24-month follow-up radiographs and the Scoliosis Research Society-22 (SRS-22) scores were reevaluated. The Cobb angle of the main and accompanying curves, the correction rate, and the flexibility of the curves were calculated. RESULTS: The mean preoperative Cobb angles were 57.03° and 57.46°, the mean postoperative Cobb angles were 14.93° and 14.4°, and the mean correction rates were 76.22% and 75.31% in IPSC and CPSC groups, respectively (p>0.05). The preoperative and postoperative accompanying curve magnitudes and correction rates were similar (p>0.05). These radiographic outcomes were also consistent with the SRS-22 scores. CONCLUSION: Both the pedicle screw constructs had satisfactory outcomes following the surgery, which were confirmed by both the SRS-22 scores and radiographs taken perioperatively and at follow-ups. The IPSC and CPSC groups did not demonstrate a significant change in the correction rate of the main and minor or major accompanying structural and nonstructural curves, and also in the SRS-22 scores. LEVEL OF EVIDENCE: Level III, Retrospective comparative study.


Asunto(s)
Tornillos Óseos/normas , Procedimientos Ortopédicos/instrumentación , Tornillos Pediculares/normas , Escoliosis/cirugía , Adolescente , Femenino , Estudios de Seguimiento , Humanos , Masculino , Ensayo de Materiales/métodos , Ensayo de Materiales/estadística & datos numéricos , Procedimientos Ortopédicos/métodos , Evaluación de Resultado en la Atención de Salud , Periodo Posoperatorio , Radiografía/métodos , Columna Vertebral/diagnóstico por imagen , Columna Vertebral/cirugía
18.
PLoS One ; 15(6): e0233148, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32525868

RESUMEN

Creating a secure and comfortable linkage between the residual limb and prosthetic socket in persons with lower limb amputation is a critical factor for successful rehabilitation, including ambulation and other activities of daily living. Unwanted rotation within the socket can be a clinical problem for prosthesis users. One way of addressing issues experienced with transverse plane control of the socket may be through increased friction interface forces. It has been proposed that friction at the residual limb/socket interface may be increased by adding texture to interface components. Three-dimensional (3D) printing may be used to fabricate sockets with texture patterns added to the inner socket surface. Hence, the aim of this study was to investigate the effects of socket texturing on transverse plane rotation of the socket on a mock residual limb under two suspension conditions: passive suction and active vacuum. To conduct this study, we developed a mechanical testing protocol as no standardized tests currently exist to assess prosthetic sockets. Sockets with 14 different texture patterns were fabricated using the Squirt-Shape™ 3D printer. Textured sockets were compared to an Original Squirt-Shape (OSS) socket and a smooth thermoformed socket. Sockets were fitted with a mock residual limb and bi-axially loaded to 350 N compression with simultaneous rotation (2.5°, 5° and 7.5°) using a custom rotation assembly attached to a uniaxial hydraulic material testing system. There was a statistically significant three-way interaction between suspension, angle and texture (p < 0.0005). Torques between textured and reference sockets, for all rotation angles and both suspension conditions, were significantly different (p < 0.0005). Using newly developed testing protocols, it was demonstrated that some texture patterns significantly increased torque (i.e., resistance against unwanted rotation) in the transverse plane compared to both OSS and smooth sockets, especially for passive suction. Rotation testing of sockets may provide insight into socket design to improve suspension in the transverse plane.


Asunto(s)
Fricción/fisiología , Ensayo de Materiales/métodos , Diseño de Prótesis/métodos , Miembros Artificiales/efectos adversos , Humanos , Fenómenos Mecánicos , Presión , Ajuste de Prótesis/métodos , Rotación , Soporte de Peso/fisiología
19.
In Vivo ; 34(3 Suppl): 1637-1644, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-32503823

RESUMEN

BACKGROUND: Sneezes produce many pathogen-containing micro-droplets with high velocities of 4.5-50.0 m/s. Face masks are believed to protect people from infection by blocking those droplets. However, current filtration efficiency tests can't evaluate masks under sneeze-like pressure. The goal of this study was to establish a method to evaluate the filtration efficiency of mask materials under extreme conditions. MATERIALS AND METHODS: Efficiency of surgical masks, gauze masks, gauze, cotton, silk, linen and tissue paper on blocking micro-droplet sized starch particles (average 8.2 µm) and latex microspheres (0.75 µm) with a velocity of 44.4 m/s created by centrifugation was qualitatively analyzed by using imaging-based analysis. RESULTS: The 4 layers of silk could block 93.8% of microspheres and 88.9% of starch particles, followed by the gauze mask (78.5% of microspheres and 90.4% of starch particles) and the 2 layers of cotton (74.6% of microspheres and 87.5-89.0% of particles). Other materials also blocked 53.2-66.5% of microspheres and 76.4%-87.9% of particles except the 8 layers of gauze which only blocked 36.7% of particles. The filtration efficiency was improved by the increased layers of materials. CONCLUSION: Centrifugation-based filtration efficiency test not only compensates shortcomings of current tests for masks, but also offers a simple way to explore new mask materials during pandemics. Common mask materials can potentially provide protection against respiratory droplet transmission.


Asunto(s)
Centrifugación/métodos , Control de Infecciones/instrumentación , Máscaras , Ensayo de Materiales/métodos , Estornudo , Filtración , Humanos , Interacciones Hidrofóbicas e Hidrofílicas , Microesferas , Papel , Tamaño de la Partícula , Material Particulado , Presión , Electricidad Estática , Textiles
20.
J Vis Exp ; (159)2020 05 17.
Artículo en Inglés | MEDLINE | ID: mdl-32478730

RESUMEN

The properties of cured wood adhesives are difficult to study because of the loss of water and other components to the wood, the influence of wood on the adhesive cure, and the effect of adhesive penetration on the wood interphase; thus, normal testing of a neat adhesive film is generally not useful. Most tests of wood adhesive bond strength are slow, laborious, can be strongly influenced by the wood and do not provide information on the kinetics of cure. Test method ASTM D 7998-19, however, can be used for fast evaluation of the strength of wood bonds. The use of a smooth, uniform, and strong wood surface, like maple face-veneer, and sufficient bonding pressure reduces the adhesion and wood strength effects on bond strength. This method has three main applications. The first is to provide consistent data on bond strength development. The second is to measure the dry and wet strengths of bonded lap shear samples. The third is to better understand the adhesive heat resistance by quickly evaluating thermal sensitivity and distinguishing between thermal softening and thermal degradation.


Asunto(s)
Adhesivos/química , Ensayo de Materiales/métodos , Madera/química , Resistencia al Corte
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