Abstract Powder coatings have been used for coating metal substrates in industrial applications. The incorporation of nanofillers as muscovite mica and montmorillonite (MMT) can improve the properties of the coatings. The objective of this study is to develop, apply and characterize a hybrid powder coating (30% epoxy/70% polyester) adding nanofillers in concentrations of 2, 4 and 6 phr separately in a twin screw extruder. The characterization of the coatings was performed by thermal, mechanical and chemical analysis. The incorporation of clay into the polymer increased the surface roughness resulting in a diffuse reflection of incident light and on a gloss reduction. The muscovite mica presented a lamellar structure, constituted by a set of overlapping parallel plates. The morphology analysis showed that the MMT presented irregular agglomerates resulting in inferior mechanical properties to coatings with muscovite mica. In the salt spray test, all samples showed high corrosion protection, around 850 hours.

Introduction: The effects of extracorporeal shock wave therapy (ESWT) have been investigated in human osteoblasts, fracture foci, nonunion and periosteum cells. The best results of nonunion treatment with ESWT have been documented for hypertrophic type. The objective of this study was to investigate the effects of ESWT in an atrophic nonunion focus generated in a rabbit tibia model. Methods: Three groups were included: A, fractures receiving ESWT; B (“control”), fractures not receiving ESWT, and C, no fractures (right leg). A total of 37 New Zealand white and skeletally mature rabbits (cuniculus NV) were treated. Periosteum was cauterized using bipolar electrocautery at 20 mm in both bone stumps (proximal and distal). Then ESWT was applied in one session. Staining with hematoxylin-eosin was used. A biomechanical analysis with a 3-point loading system was performed. Maximum load and elastic modulus were evaluated in each group. Results: Histological study evidenced signs of union (periosteal and endosteal fracture callus) which were considerably larger in tibias of Group A (treated with ESWT) as compared to the control group (Group B). Conclusion: In an experimental model of atrophic pseudarthrosis caused by electrocautery in tibias of rabbits, significant radiographic and histological changes were observed after focus intervention with the application of ESWT.

Introducción: Los efectos de las ondas de choque extracorpóreas se han investigado en osteoblastos humanos, focos fracturarios, seudoartrosis y células periósticas. Los mejores resultados del tratamiento de la seudoartrosis con ondas de choque extracorpóreas se han documentado para seudoartrosis hipertróficas. El objetivo de este estudio fue investigar el efecto de la terapia con ondas de choque extracorpóreas sobre un foco de seudoartrosis “atrófica” generado en tibia de conejo. Métodos: Se establecieron tres grupos: A, fracturados sometidos a ondas de choque extracorpóreas; B (“control”), fracturados no sometidos a ondas de choque y C, no fracturados (pierna derecha). Se trataron 37 conejos (cuniculus NV) blancos y esqueléticamente maduros de Nueva Zelanda. Se practicó la cauterización del periostio con electrobisturí bipolar en una extensión de 20 mm, en ambos muñones óseos (proximal y distal). Luego se aplicaron ondas de choque extracorpóreas en una sola sesión. Se realizaron tinciones con hematoxilina-eosina. Se efectuó el análisis biomecánico con un método de carga a “3 puntos”. Se estudiaron la carga máxima aplicada y el módulo de elasticidad para cada grupo. Resultados: El estudio histológico permitió registrar signos de consolidación -callo fracturario perióstico y endostal- considerablemente mayores en las tibias de los animales del grupo A (tratado con ondas de choque extracorpóreas) que en las del grupo B “control”. Conclusión: En un modelo experimental original de seudoartrosis atrófica generada por electrocauterización en tibia de conejos, se registraron cambios significativos radiográficos e histológicos luego de la intervención del foco mediante ondas de choque extracorpóreas.

AbstractPolymer coatings have been used for the corrosion protection of metal surfaces acting as a physical barrier against several corroding media. In spite of the good efficiency of these coatings their resistance is limited due to the presence of localized defects which give place to localized corrosion. Aiming to improve the barrier properties of these coatings this work has proposed the use of nanocomposites as powder coatings based on a standard formulation of a commercial powder varnish. Nanocomposites with 2 and 4 wt% contents of organophilic montmorillonite (OMMT) were obtained in the molten state through of a co-rotating twin-screw extruder. The application of the nanocomposite coatings was performed by electrostatic pulverization on mild steel panels. The coatings were characterized to determine their structure using X-ray diffraction (XRD). The morphologies of the coatings were assessed using transmission electron microscopy (TEM). Gloss and adhesion measurements and the flexibility and impact resistance of the coatings were included in the physical assessment of the coatings. The corrosion performance was evaluated by the salt spray test and by electrochemical impedance spectroscopy (EIS). The coatings with clays presented predominantly exfoliated structures, with good dispersion of OMMT in the epoxy matrix. The addition of OMMT reduced the impact resistance, flexibility and gloss but increased the barrier properties of the coatings. The best corrosion performance in NaCl solution was achieved for 4 wt% OMMT.

Background: It has been shown that a reduction in mean arterial pressure (MAP) causes a haemostatic effect in the intramedullary canal. We found no publications describing an association between in vivo MAP and cementation defects during arthroplasty. This study investigates the association between these two factors. Methods: Fifty six patients were selected after total hip replacement according to a convenience sample. Mean arterial pressure (MAP) during the cementation process was obtained reviewing the intraoperative anaesthetic records. Bubbles and radiolucencies in the bonecement interphase were considered cementation defects. Regression calculations were made using the Spearman method across both variables. Results: The amount of bubbles found in the femoral region was not related to the MAP,R2 = 0,02 (p > 0,05). A statistically significant association between radiolucencies in the cement mantle and MAP values was found. R2 = 0,7 (p < 0,05). Conclusions: A linear correlation was established between cementation defects like radiolucencies and MAP values. This correlation was not seen with bubble defects.

Introducción: Se ha demostrado que la disminución de la presión arterial media (PAM) produce un efecto hemostático en el conducto endomedular. En relación con la calidad del cementado en las artroplastias, no se han hallado publicaciones que correlacionen in vivo los valores de PAM y los defectos de cementación. Se diseñó un estudio de corte transversal de correlación con el objetivo de investigar la posible asociación entre estos dos factores. Materiales y métodos: Se seleccionaron 56 pacientes sometidos a artroplastias primarias de cadera, de acuerdo con un muestreo por conveniencia. Los valores de presión arterial media durante el cementado se obtuvieron mediante la revisión de los monitoreos anestésicos intraoperatorios. Se consideraron defectos de cementado las burbujas y radiolucencias presentes en la interfaz hueso-cemento. Se efectuaron cálculos de regresión con el método de Spearman entre ambas variables. Resultados: La cantidad de burbujas encontradas por región femoral no se correlacionó con la PAM, R2 = 0,02 (p > 0,05). Se observó una asociación estadísticamente significativa entre la mayor cantidad de radiolucencias en el manto de cemento y los mayores valores de PAM, R2 = 0,7 (p < 0,05). Conclusiones: Se ha logrado establecer una correlación lineal entre la aparición de defectos del cementado en forma de radiolucencias y los valores de la PAM. En cuanto a los defectos denominados burbujas, no se observó tal correlación.