Experimental and numerical study of vacuum resin infusion of stiffened carbon fiber reinforced panels

Liquid resin infusion processes are becoming attractive for aeronautic applications as an alternative to conventional autoclave-based processes. They still present several challenges, which can be faced only with an accurate simulation able to optimize the process parameters and to replace traditional time-consuming trial-and-error procedures. This paper presents an experimentally validated model to simulate the resin infusion process of an aeronautical component by accounting for the anisotropic permeability of the reinforcement and the chemophysical and rheological changes in the crosslinking resin. The input parameters of the model have been experimentally determined. The experimental work has been devoted to the study of the curing kinetics and chemorheological behavior of the thermosetting epoxy matrix and to the determination of both the in-plane and out-of-plane permeability of two carbon fiber preforms using an ultrasonic-based method, recently developed by the authors. The numerical simulation of the resin infusion process involved the modeling of the resin flow through the reinforcement, the heat exchange in the part and within the mold, and the crosslinking reaction of the resin. The time necessary to fill the component has been measured by an optical fiber-based equipment and compared with the simulation results

Bio-based furan-polyesters/graphene nanocomposites prepared by in situ polymerization

In situ intercalative polymerization has been investigated as a strategic way to obtain poly(propylene 2,5-furandicarboxylate) (PPF) and poly(hexamethylene 2,5-furandicarboxylate) (PHF) nanocomposites with different graphene types and amounts. Graphene (G) has been dispersed in surfactant stabilized water suspensions. The loading range in composites was 0.25–0.75 wt %. For the highest composition, a different type of graphene (XT500) dispersed in 1,3 propanediol, containing a 6% of oxidized graphene and without surfactant has been also tested. The results showed that the amorphous PPF is able to crystallize during heating scan in DSC and graphene seems to affect such capability: G hinders the polymer chains in reaching an ordered state, showing even more depressed cold crystallization and melting. On the contrary, such hindering effect is absent with XT500, which rather induces the opposite. Concerning the thermal stability, no improvement has been induced by graphene, even if the onset degradation temperatures remain high for all the materials. A moderate enhancement in mechanical properties is observed in PPF composite with XT500, and especially in PHF composite, where a significative increase of 10–20% in storage modulus E’ is maintained in almost all the temperature range. Such an increase is also reflected in a slightly higher heat distortion temperature. These preliminary results can be useful in order to further address the field of application of furan-based polyesters; in particular, they could be promising as packaging materials

CTX-M-15 Type Extended-Spectrum Beta-Lactamase-Producing Enterobacter cloacae In Bioaerosol of a Municipal Solid Waste Recycling Plant: A New Possible Reservoir of Infection?

Background: Although there are many reports of antibiotic resistant microorganisms released from the treated municipal wastewater, less attention has been given to other waste treatment activities. We report the occurrence of antibiotic resistant strains isolated from the working setting of a solid waste recycling plant in Italy which serves 195 municipalities. Methods: To assess microbial contamination levels, several sampling points were chosen for their relevance in evaluating exposure of the workers to biological risk, especially during indoor operations. Active sampling was carried out using the Surface Air System and Rodac plate method was applied to surface sampling. Species identification and antimicrobial susceptibilities were obtained by Vitek2 System (bioMérieux, France) and by the agar-diffusion method. The presence of resistance genes was investigated by multiplex PCR assay. Results: In all sampling points a significant contamination of aerosol was detected, although the total microbial counts resulted within the limit proposed by the National authority (10000 CFU/sqm). The counts of Enterobacteriaceae were always above the limit of 100 CFU/sqm and strains of Enterobacter cloacae resistant to third generation cephalosporins were detected, carrying the blaCTX-M15 gene. Conclusions: The contamination of workplace with multidrug-resistant strains is a crucial area for public health actions to avoid the conjunction of factors that promote evolution and spread of antibiotic resistance

GnRH agonist versus GnRH antagonist in in vitro fertilization and embryo transfer (IVF/ET)

Several protocols are actually available for in Vitro Fertilization and Embryo Transfer. The review summarizes the main differences and the clinic characteristics of the protocols in use with GnRH agonists and GnRH antagonists by emphasizing the major outcomes and hormonal changes associated with each protocol. The majority of randomized clinical trials clearly shows that in "in Vitro" Fertilization and Embryo Transfer, the combination of exogenous Gonadotropin plus a Gonadotropin Releasing Hormone (GnRH) agonist, which is able to suppress pituitary FSH and LH secretion, is associated with increased pregnancy rate as compared with the use of gonadotropins without a GnRH agonist. Protocols with GnRH antagonists are effective in preventing a premature rise of LH and induce a shorter and more cost-effective ovarian stimulation compared to the long agonist protocol. However, a different synchronization of follicular recruitment and growth occurs with GnRH agonists than with GnRH antagonists. Future developments have to be focused on timing of the administration of GnRH antagonists, by giving a great attention to new strategies of stimulation in patients in which radio-chemotherapy cycles are needed

Curve classes on irreducible holomorphic symplectic varieties

We prove that the integral Hodge conjecture holds for 1-cycles on irreducible holomorphic symplectic varieties of K3 type and of Generalized Kummer type. As an application, we give a new proof of the integral Hodge conjecture for cubic fourfolds.Comment: 15 page

The Relationship between Gut Microbiota and Respiratory Tract Infections in Childhood: A Narrative Review

Respiratory tract infections (RTIs) are common in childhood and represent one of the main causes of hospitalization in this population. In recent years, many studies have described the association between gut microbiota (GM) composition and RTIs in animal models. In particular, the “inter-talk” between GM and the immune system has recently been unveiled. However, the role of GM in human, and especially infantile, RTIs has not yet been fully established. In this narrative review we provide an up-to-date overview of the physiological pathways that explain how the GM shapes the immune system, potentially influencing the response to common childhood respiratory viral infections and compare studies analysing the relationship between GM composition and RTIs in children. Most studies provide evidence of GM dysbiosis, but it is not yet possible to identify a distinct bacterial signature associated with RTI predisposition. A better understanding of GM involvement in RTIs could lead to innovative integrated GM-based strategies for the prevention and treatment of RTIs in the paediatric population

Valorization of wheat bran agro-industrial byproduct as an upgrading filler for mycelium-based composite materials

When considered by a biorefinery approach, an agroindustrial byproduct such as wheat bran can find a new standing in the field of fabrication of mycelium-based materials. The present work reports on a systematic study on the effect of wheat bran as an upgrading feedstock for the growth and development of fully biobased and biodegradable composites. Two families of materials based on bran/cotton and bran/hemp mixtures were fabricated on an industrial scale. The natural materials thus obtained were fully characterized and their end-life was assessed in composting conditions. The research focusses on two main aspects: the nutritional contribution of bran for the fungal growth and its effect on the mechanical properties as a filler in the final composites. It must be noted that the valorization and exploitation of a byproduct such as bran can have a considerable impact on the industrial production of mycelium-based composite materials, by reducing the time of production while increasing their mechanical performances

Natural deep eutectic solvents as thermostabilizer for Humicola insolens cutinase

As a new generation of green solvents, deep eutectic solvents (DESs) are considered a promising alternative to current harsh organic solvents and find application in many chemical processing methods such as extraction and synthesis. DESs, normally formed by two or more components via various hydrogen bond interactions, offer high potential as medium for biocatalysis reactions where they can improve efficiency by enhancing substrate solubility and the activity and stability of the enzymes. In the current study, the stabilization of Humicola insolens cutinase (HiC) in natural deep eutectic solvents (NADESs) was assessed. The best hydrogen bond donor among sorbitol, xylitol, erythritol, glycerol and ethylene glycol, and the best acceptor among betaine, choline chloride, choline acetate, choline dihydrogen citrate and tetramethylammonium chloride, were selected, evaluating binding energies and molecular orientations through molecular docking simulations, and finally used to prepare NADES aqueous solutions. The effects of component ratio and NADES concentration on HiC thermostability at 90 degrees C were also investigated. The choline dihydrogen citrate:xylitol, in a 1:1 ratio with a 20 wt% concentration, was selected as the best combination in stabilizing HiC, increasing its half-life three-fold

Impact of comprehensive pulmonary rehabilitation on anxiety and depression in hospitalized COPD patients.

To prospectively evaluate the effect of inpatient pulmonary rehabilitation (iPR) on anxiety and depression as outcome measures in patients with COPD, we studied 149 consecutive adults COPD referred to our iPR after an exacerbation. Patients were divided according to the GOLD staging into: Group 1 (stage 2a, n = 48, FEV1 63 +/- 9% pred.), Group 2 (stage 2b, n = 53, FEV1 42 +/- 6% pred.) and Group 3 (stage 3, n = 48, FEV1 25 +/- 7% pred.). The iPR consisted of twelve 3-hours daily sessions. Hospital Anxiety Depression (HAD) Scale as well as 6-minute walk (6MWD) with evaluation of dyspnea (D) and leg fatigue (F) at rest and end of effort, and health related quality of life by means of St. George Respiratory Questionnaire (SGRQ) were assessed before (T0) and after (T1) the iPR. 6MWD, D and F at end of effort and SGRQ total score similarly improved (p < 0.001) in all groups after iPR. The mean level of HAD-anxiety (from 9.1 +/- 4.0 to 7.7 +/- 3.5, from 9.0 +/- 4.6 to 7.2 +/- 4.6 and from 8.1 +/- 4.1 to 6.7 +/- 4.3 in group 1,2 and 3 respectively) and HAD-depression (from 9.4 +/- 3.5 to 8.2 +/- 3.5, from 9.1 +/- 4.2 to 8.2 +/- 4.5 and from 9.0 +/- 4.0 to 7.4 +/- 4.5 respectively) similarly changed (p < 0.0001) over time in all groups. The total percentage of patients with abnormal score (> 10) of HAD-anxiety (from 31% to 21%) and HAD-depression (from 30% to 22%) significantly decreased (p < 0.05) after the iPR. Inpatient pulmonary rehabilitation may improve levels of anxiety and depression as well as symptoms, exercise capacity and health related quality of life in moderate to severe COPD patients after an acute exacerbation