Polypropylene surface modification by low pressure plasma to increase adhesive bonding: Effect of process parameters

The purpose of this study is to evaluate the effect of a cold plasma surface treatment of polypropylene substrates with the aim of increasing their adhesion characteristics. These substrates were treated with plasma, using different process parameters such as power, time and working gas. The effect of the treatment has been studied through a surface characterization, analyzing the chemical species created on the topmost layer of the substrates thanks to the plasma treatment and evaluating the surface energy, through contact angle measurements. Then, untreated and plasma treated samples with various parameters were used to create single overlapping bonded joints and evaluate the effect of the surface treatment on the mechanical characteristics of the joints. Experimental results show that plasma treatment is an effective treatment for the surface preparation of polypropylene adhesive bonding. In fact, the increase in surface energy and the formation of chemical bonds between oxygen and carbon have favored the adhesion, thus increasing the mechanical strength of the joint

cold plasma pretreatment of carbon fibre composite substrates to improve adhesive bonding performance

The purpose of the paper is to investigate the effects of low pressure plasma treatment on wettability of carbon fibre reinforced polymer samples and on shear properties of adhesive bonded joints based on these substrates. In particular, two plasma process parameters, exposure time and power input, were optimized, performing contact angle evaluation on lap-shear tests. The plasma treatment was also compared with a conventional mechanical abrasion and untreated and only degreased specimens. The experimental results show that choosing the optimal parameters is possible to improve the wettability of composite substrates and reduce the contact angle

Hybrid FSWeld-bonded joint fatigue behaviour

Aluminium alloys, widely used in aeronautics, are increasingly involved in the automotive industry due to the good relationship between mechanical strength and specific weight. The lightening of the structures is the first objective, which allows the decreasing in the weight in motion. The use of aluminium alloys has also seen the introduction of the Friction Stir Welding (FSW) technique for the production of structural overlapping joints. FSW allows us to weld overlap joints free from defects, but with the presence of a structural notch further aggravated by the presence of a "hook" defect near the edge of the weld. Furthermore, FSW presents a weld penetration area connected to the tool geometry and penetration. The experimental activity will be focused on the combination of two different joining techniques, which can synergistically improve the final joint resistance. In particular, the welding and bonding process most commonly known as weld-bonding is defined as a hybrid process, as it combines two different junction processes. In this paper we analyse FSWelded AA6082 aluminium alloy overlapped joint with the aim of quantitatively evaluating the improvement provided by the presence of an epoxy adhesive between the plates. After optimising the weld-bonding process, the mechanical behaviour of welded joints will be analysed by static and dynamic tests. The presence of the adhesive should limit the negative effect of the structural notch inevitable in a FSW overlapped joint

Serum thyroid hormone antibodies are frequent in patients with polyglandular autoimmune syndrome type 3, particularly in those who require thyroxine treatment

Polyglandular autoimmune syndrome (PAS) type 3 consists of autoimmune thyroid disease (AITD) coexisting with ≥1 non-thyroidal autoimmune disease (NTAID) other than Addison’s disease and hypoparathyroidism. We evaluated the prevalence and repertoire of thyroid hormones antibodies (THAb) in PAS-3 patients. Using a radioimmunoprecipation technique, we measured THAb (T3IgM, T3IgG, T4IgM, and T4IgG) in 107 PAS-3 patients and 88 controls (patients with AITD without any NTAID). Based on the selective coexistence of AITD with one NTAID (chronic autoimmune gastritis, non-segmental vitiligo or celiac disease), patients were divided into group 1 (chronic autoimmune gastritis positive, n = 64), group 2 (non-segmental vitiligo positive, n = 24), and group 3 (celiac disease positive, n = 15). At least one of the four THAb was detected in 45 PAS-3 patients (42.1%) and 28 controls (31.8%, P = 0.14), with similar rates in the three PAS-3 groups. The rates of T3Ab, T4Ab, and T3 + T4Ab were similar in groups 1 and 2, while in group 3, T3Ab was undetected (P = 0.02). In PAS-3 patients, the rate of levothyroxine treatment was greater in THAb-positive patients compared to THAb-negative patients (76.7 vs. 56.1%, P = 0.03, RR = 1.4, 95% CI 1.03–1.81). Not unexpectedly, levothyroxine daily dose was significantly higher in group 1 and group 3, namely in patients with gastrointestinal disorders, compared to group 2 (1.9 ± 0.4 and 1.8 ± 0.3 vs. 1.5 ± 0.2 μg/kg body weight, P = 0.0005 and P = 0.004). Almost half of PAS-3 patients have THAb, whose repertoire is similar if chronic autoimmune gastritis or celiac disease is present. A prospective study would confirm whether THAb positivity predicts greater likelihood of requiring levothyroxine treatment

Laser surface texturing of polypropylene to increase adhesive bonding

In this paper, the main parameters of laser surface texturing of polymeric substrates have been studied. The final aim of the texturing is to increase the performance of bonded joints of grey-pigmented polypropylene substrates. The experimental investigation was carried out starting from the identification of the most effective treatment parameters, in order to achieve a good texture without compromising the characteristics of the bulk material. For each of these parameters, three values were individuated and 27 sets of samples were realised. The surface treatment was analysed and related to the mechanical characteristics of the bonded joints performing lap-shear tests. A statistical analysis in order to find the most influential parameter completed the work

A Cognitive Model for Emergency Management in Hospitals: Proposal of a Triage Severity Index

Hospitals play a critical role in providing communities with essential medical care during all types of disasters. Any accident that damages systems or people often requires a multifunctional response and recovery effort. Without an appropriate emergency planning, it is impossible to provide good care during a critical event. In fact, during a disaster condition, the same “critical” severity could occur for patients. Thus, it is essential to categorize and to prioritize patients with the aim to provide the best care to as many patients as possible with the available resources. Triage assesses the severity of patients to give an order of medical visit. The purpose of the present research is to develop a hybrid algorithm, called triage algorithm for emergency management (TAEM). The goal is twofold: First, to assess the priority of treatment; second, to assess in which hospital it is preferable to conduct patients. The triage models proposed in the literature are qualitative. The proposed algorithm aims to cover this gap. The model presented exceeds the limits of literature by developing a quantitative algorithm, which performs a numerical index. The hybrid model is implemented in a real scenario concerning the accident management in a petrochemical plant

A Response Surface Methodology Approach to Improve Adhesive Bonding of Pulsed Laser Treated CFRP Composites

In this work, a response surface-designed experiment approach was used to determine the optimal settings of laser treatment as a method of surface preparation for CFRP prior to bonding. A nanosecond pulsed Ytterbium-doped-fiber laser source was used in combination with a scanning system. A Face-centered Central Composite Design was used to model the tensile shear strength (TSS) of adhesive bonded joints and investigate the effects of varying three parameters, namely, power, pitch, and lateral overlap. The analysis was carried out considering different focal distances. For each set of joints, shear strength values were modeled using Response Surface Methodology (RSM) to identify the set-up parameters that gave the best performance, determining any equivalent conditions from a statistical point of view. The regression models also allow the prediction of the behavior of the joints for not experimentally tested parameter settings, within the operating domain of investigation. This aspect is particularly important in consideration of the process optimization of the manufacturing cycle since it allows the maximization of joint efficiency by limiting the energy consumption for treatment

Effect of fibre laser marking on surface properties and corrosion resistance of a Fe-Ni-Cr alloy

Fiber laser techniques are increasing their use in many applications, including modification of material surface properties. In particular they are often used for materials' marking as a non-contact processing. In spite of this, the impact of the laser beam on the surface causes metallurgical and morphological changes. The developments during the laser-material interaction can also affect other surface properties, especially corrosion properties which are crucial in the case of Iron-Nickel alloys. Effect of laser marking on a Fe-Cr-Ni alloy using a Tm-fibre laser (IPG Photonics TRL1904; maximum power: 50W, wavelength: 1904 nm), is described in this paper. In order to evaluate the effect of the laser on corrosion properties a specific ageing test in salt spray has been performed. Moreover, superficial morphology analyses have been performed on samples before and after corrosion tests. Possibilities and limitations of laser marking on these alloys have been discussed, in particular from the point of view of the marked surface corrosion resistance preservation

Low-pressure plasma treatment of CFRP substrates for epoxy-adhesive bonding: an investigation of the effect of various process gases

This work reports a systematic and quantitative evaluation of the effects induced on the adhesive properties of carbon fiber reinforced polymer (CFRP) substrates by various vacuum cold-plasma treatments. In particular, surface activation of the CFRP substrates was performed using several combinations of exposure time, plasma power, and processing gas (air, O 2 , Ar and N 2 ). By comparing these plasma treatments with conventional techniques of abrasion and peel ply, it was possible to substantially increase the performance of the adhesively bonded joints made by overlapping the CFRP substrates with a structural epoxy resin. On each differently treated surface, measurements of roughness and of wettability were performed, allowing the evaluation of the increase in surface energy after the plasma treatment. XPS analyses allowed the identification of the chemical state of the substrates and showed an in-depth functionalization of the outer layer of the CFRP material. The experimental results show that an engineered plasma treatment of the CFRP substrates allows one to modify the surface morphology and both wetting and chemical activation properties of the treated surfaces, resulting in an increased mechanical shear strength of the joints

SECCA procedure for anal incontinence and antibiotic treatment: a case report of anal abscess

Background: Fecal Incontinence (FI) can seriously affect quality of life. The treatment of fecal incontinence starts conservatively but in case of failure, different surgical approaches may be proposed to the patient. Recently several not invasive approaches have been developed. One of these is the radiofrequency (RF) energy application to the internal anal sphincter. Case presentation: We report a rare case of an anal abscess related to a SECCA procedure in a 66-year-old woman affected by gas and FI for twenty years. Conclusions: The complications post-SECCA procedure reported in literature are generally not serious and often self-limited, such as bleeding or anal pain. This is a case of an anal abscess. We suggest that this finding could consolidate the importance of administering antibiotic therapy to patients and to run a full course of at least 6 days rather than a short-term (24 h) therapy, with the aim to minimize the incidence of this complication