Indirect rapid tooling with aluminium and milled fibre reinforced resins

It is well known that Rapid Prototyping (RP) and Rapid Tooling (RT) are fundamental technologies to reduce the time tomarket and consequently increase productivity and competitiveness of companies working in different industrial sectors.RT with epoxy resins is presently accepted as an established process of indirect rapid tooling. However, patents,processing difficulties and companies limitations disable a wider implementation of this technology.This paper presents the experimental results of a detailed work, conducted at INEGI, to manufacture moulds for plasticinjection, with tailored properties, using RP models and aluminium filled and fibres reinforced epoxy resins

The effect of aluminium granulometry on the behaviour of filled epoxy resins for rapid tooling

Aluminium filled epoxies moulds have beenused in indirect rapid tooling. These moulds, whichhave a low cost processing, are very competitive,when applied in the manufacturing of low volumeseries.The geometry and the size distribution of thealuminium particles affect significantly the powderpacking density, the resin ratio, the thermalconductivity, the curing time, the homogeneity andthe mechanical characteristics of the tool.Using three high temperature epoxy resins itwas possible to understand the resin behaviour inthe presence of the aluminium filler and formulatefilled resins with the best compromise ofmechanical, thermal and processing performance

Infection By The Human Papillomavirus In Teenagers Sexually Active: Clinic And Subclinic Manifestations.

This research studies the association of the cervical condyloma with the intraepithelial neoplasia, during sex activity, pregnancy, diagnose methods, cytology and colposcopy in teenagers. The objective of this research is to study the propaedeutics for the uterine coli condyloma diagnose in a group of teenagers. For this purpose, we have studied 131 teenagers sexually active with ages between 14 and 19 years and presenting histologically confirmed uterine coli condyloma. Association with intraepithelial neoplasia, sexual activity duration, method of diagnose, pregnancy analysis, cytology and colposcopy results and association with vulva and vagina injuries were evaluated. The high association rate with condyloma and intraepithelial neoplasia after a short time of sexual activity and the none presence of macroscopic warts in the genital organs in 80% of cases presenting cervical condyloma, demonstrate that: a more careful investigation with colposcopy and biopsy of the inferior genitals of the women-teenagers sexually active is needed, when presenting modified cervical cytology.113494895

Corrosion resistance in artificial perspiration of Cr-based decorative coatings

We aim at developing hexavalent chromium-free coatings for frequently touched decorative parts. Cr(N,O) and multilayered CrN/CrO coatings were deposited by means of reactive magnetron sputtering. All samples presented good adhesion to the substrates enhanced by an epoxy layer designed to enhance PVD coating adhesion. Similar substrates are found in the automotive industry and can be used in appliances where a metallic finish is desired by the consumer. Corrosion behavior was induced, using artificial sweat to simulate long exposure to human touch for 96 h. In potentiodynamic polarization tests, the coatings were revealed to be nobler than the substrate alone. Cr displayed a non-existent passivation region, while gCrN exhibited a quick passivation of the surface and its respective breakdown and several current fluctuations, indicating the occurrence of pitting, which was confirmed by SEM micrography after the corrosion. Regarding EIS results, all films depicted a diminution of impedance modulus (|Z|) after 96 h, which indicates a diminution of corrosion resistance against artificial sweat. Nitride films exhibited the worst anticorrosive features. On the other hand, Cr and CrO exhibited the highest |Z| values. These results are corroborated by low the corrosion rates of both coatings. The equivalent electrical circuit allows us to confirm oxide formation in the outermost layer of the films due to electrolyte/surface interaction, indicating a self-protecting mechanism. Nitride films showed the lowest values and less corrosion resistance, confirming the results obtained in polarization potentiodynamic tests. The coatings developed in this work, namely Cr and CrO, showed a promising corrosion resistance behavior that could endure a lifetime of frequent human touch in various decorative applications either automotive or general appliances.This work was supported by COMPETE 2020 a Portuguese and European Union initiative through the Project POCI-01-0247-FEDER-072607, R&D and production of logos for the automotive industry. This research was sponsored by Norte2020, through European Social Fund (FSE), under the National Doctoral Program in “Surfaces Engineering and Protection”, NORTE-08-5369-FSE-000047. This research is sponsored by national funds through FCT—Fundação para a Ciência e a Tecnologia, under the Ph.D. Research Scholarship with Reference No. 2020.09436.BD. Author Maria José Lima acknowledges FCT for the research contract 2021.00675.CEECIND. This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of Strategic Funding (co-financed via UIDB/00285/2020 and UIDB/04650/2020) and LA/P/0112/2020

Surface functionalization of cuttlefish bone-derived biphasic calcium phosphate scaffolds with polymeric coatings

Cuttlefish bone (CB) has been explored as biomaterial in the bone tissue-engineering field due to its unique porous structure and capacity of the aragonite mineral to be hydrothermally converted into calcium phosphates (CaPs). In the present study, undoped and ion (Sr2+, Mg2+ and/or Zn2+) doped biphasic calcium phosphate (BCP) scaffolds were prepared by hydrothermal transformation (HT, 200 °C, 24 h) of CB. The obtained scaffolds were sintered and then coated with two commercial polymers, poly(ε-caprolactone) (PCL) or poly(DL-lactide) (PDLA), and with two synthesized ones, a poly(ester amide) (PEA) or a poly(ester urea) (PEU) in order to improve their compressive strength. The scaffolds were characterized by X-ray diffraction (XRD) coupled with structural Rietveld refinement, Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). The results demonstrate that CB could be entirely transformed into BCPs in the presence or absence of doping elements. The initial CB structure was preserved and the polymeric coatings did not jeopardize the interconnected porous structure. Furthermore, the polymeric coatings enhanced the compressive strength of the scaffolds. The in vitro bio-mineralization upon immersing the scaffolds into simulated body fluid (SBF) demonstrated the formation of bone-like apatite surface layers in both uncoated and coated scaffolds. Overall, the produced scaffolds exhibit promising properties for bone tissue engineering applications.publishe