METAL REPLACEMENT WITH POLYMERS IN PROFESSIONAL FOOD PROCESSING APPLIANCES

Metal replacement is one of the most promising solutions in industrial appliances, both to save money, reduce weight and increase competitiveness on market. Polymers in cooking environments are risky materials if exposed to heat and fire, and flame retardant additives and fire behaviour are key points that has to be considered before replace metals and in general in initial materials selection during appliances project and production

Upcycling of polyester fiber and garment-textile waste

This research is part of the project MATE.RIA, aimed at extending the life of post-consumer garment-textiles and identifying a new market for polyethylene terephthalate (PET) waste produced during fiber manufacturing. Here we investigate the possibility of developing innovative products exploiting the thermal insulation capability of textiles for architectural applications. The materials considered in this work are the polyester fiber waste from the production line and the end-of-life garment-textiles, provided by the project partners FranaPolifibre and HUMANA, respectively. Gel Permeation Chromatography, Differential Scanning Calorimetry, and uniaxial tensile tests were used to preliminarily determine structural, thermal, and mechanical properties. The materials were then used to produce prototype of thermoregulatory panels, which were obtained by applying a layer of PET to one or both fabric surfaces: the fabric acts as a thermal insulator while the PET layer provides rigidity. Two techniques were used to apply PET layers on a fabric: textile dip coating in PET solution and coupling with cast film. Both processes required the preparation of a PET solution. Hexafluoro isopropanol (HFIP) has been selected as solvent due to its compatibility with the textiles. A solution of 250 g/L was utilized for dip coating. Textiles varying in percentages of cotton and polyester were dip-coated in a solution on their “Right side”, “Wrong side”, or on both surfaces. Cast films were obtained by 200 g/L of PET/HFIP. Dried membranes that ranged in thickness from 157 to 190 μm were coupled with the fabrics after wetting the membrane surface with additional HFIP. The thermal regulation capability of the panel could be modified through Phase Change Materials (PCMs) inclusion. Composites' morphological and porosity characteristics have been examined via optical microscopy analysis. Incorporating PCMs suitable for architectural applications into the composite is under investigation

Plasticizer design strategies enabling advanced applications of cellulose acetate

Plasticized cellulose acetate (CA) is one of the most applied bio-based polymers due to its structural properties and easy processing. Plasticizers are added to CA to increase workability, prevent degradation under processing conditions and ensure thermo-mechanical properties suitable for the intended final application. Moreover, inexpensive and non-toxic solvents enable its processing into fibers, films, and solid blocks. However, when incorporated in the polymer matrix, plasticizers are prone to migration. CA products can suffer embrittlement, cracking, warping, or discoloration during their life cycle, affecting the material’s integrity and durability. The design of new plasticizers compatible with the polymer at high concentrations, tailored to be effective in lowering the glass transition temperature, and with a low tendency to migration could considerably reduce material degradation over time. This review offers a perspective on the current plasticizers and comprehensively depicts the plasticization mechanisms in CA for internal and external plasticization. Understanding the plasticization mechanisms paves the way to identify a rationale for designing new plasticizers for this polymer

Nonlinear viscoelasticity of freestanding and polymer-anchored vertically aligned carbon nanotube foams

Vertical arrays of carbon nanotubes (VACNTs) show unique mechanical behavior in compression, with a highly nonlinear response similar to that of open cell foams and the ability to recover large deformations. Here, we study the viscoelastic response of both freestanding VACNT arrays and sandwich structures composed of a VACNT array partially embedded between two layers of poly(dimethylsiloxane) (PDMS) and bucky paper. The VACNTs tested are ∼2 mm thick foams grown via an injection chemical vapor deposition method. Both freestanding and sandwich structures exhibit a time-dependent behavior under compression. A power-law function of time is used to describe the main features observed in creep and stress-relaxation tests. The power-law exponents show nonlinear viscoelastic behavior in which the rate of creep is dependent upon the stress level and the rate of stress relaxation is dependent upon the strain level. The results show a marginal effect of the thin PDMS/bucky paper layers on the viscoelastic responses. At high strain levels (ɛ = 0.8), the peak stress for the anchored CNTs reaches ∼45 MPa, whereas it is only ∼15 MPa for freestanding CNTs, suggesting a large effect of PDMS on the structural response of the sandwich structures

Materials selection for food processing professional appliances

Professional appliances are characterized by an intense use in harsh environments; therefore, they need to communicate, through materials sensorial attributes, robustness and reliability. During their lifetime, professional appliances face specific chemical compatibility problems related to daily contact with food chemicals and detergent compounds compliance, and to misuse practices. These products are developed as tailor-made solutions, designed to satisfy both client needs and usability, even in very specific operative conditions. For this reason, they are developed on one hand through a performance driven technical design process, and on the other through a sensorial oriented materials selection, to improve the user experience with the product. From the Ashby method, the implementation of a flexible materials selection process, able to match sensorial attributes with the real products performances, needs for improvements, due to the highly competitive professional appliances market. The most common design approach in the industrial production of business to business market appliances sees the designer and the engineer as separate figures, which compel respectively to the aesthetical and emotional issues and to the technical and performances requirements. Both these figures operate materials selection with two different perspectives: the lack of communication among the two roles is often due to the different levels of analysis of the process. Electrolux Professional is trying to overcome this limit using an innovative approach, being an appropriate environment to test new solutions. A unique selection method applied to real products, able to couple qualitative and quantitative properties, and to consider both the modification of the technical and chemical properties and the material sensorial perceptions along the products life, can be the driving force of an innovative materials selection approach. The related design process will be then integrated to reach in a unique step a concept that satisfies both the technical performances and the user perception requirements

Materials selection tools in professional appliances: hypothesis to estimate materials’ performance and impact on industrial processes

Concept The use of materials’ selection in professional appliances increased in recent times, thanks to its potential pre-evaluation of materials’ performance and impact on industrial production processes. Through a collaboration among Politecnico di Milano (Department of Design and Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”) and Electrolux Professional S.p.A. (Global Research & Development, Innovation & Technologies Area), an evaluation of materials’ tangible and intangible properties has been developed using non-traditional methods. Among all the currently professional appliances, the oven environment has been chosen as the most emblematic study case. In the first part, this work evidences the major limits and critical points of the materials’ selection tools currently and most commonly proposed in industrial applications. Within these, the main key points highlighted are the translation and connection of quantitative and qualitative properties and the risk associated to the materials selection process reliability. In a second step, some ameliorative hypotheses are built to overcome these limits, using a repeatable and suitable method for different materials selection cases. Motivations and Objectives The research aim is to develop an innovative and versatile method for the materials selection in professional appliances field, used by engineers and designers. From the Ashby [1] and the Karana [2] selection strategies, the non-traditional materials selection methodology would offer a complete evaluation of materials’ tangible and intangible properties. Different variables, indeed, have been taken into consideration: material’s technical properties (e.g. mechanical, thermal and processability parameters), durability (e.g. food chemicals and detergents), food-material compliance and customer perception of properties. The need of a unique materials selection method, able to convert quantitative to qualitative evaluation of properties and to estimate the risk associated to the materials selection reliability, driven the research. A procedure, which evaluates components’ life and possible failure modes (based on DOE and FMEA) [3] [4] [5], is under development in order to integrate these information into the future products development. Results and Discussion The research presents the development of the materials selection methodology under consideration supported by some case studies that focus on durability properties of materials

Biomanufacturing of a Chitosan/Collagen Scaffold to Drive Adhesion and Alignment of Human Cardiomyocyte Derived from Stem Cells☆

Abstract The in vitro generation of a three-dimensional (3D) myocardial tissue employing cells, biomaterials, and biomolecules is a promising strategy in cardiac tissue regeneration. Despite significant progresses in this field, cellular models are not yet able to provide a source of myocardial cells that will efficiently integrate and substitute damaged myocardial tissue. Stem cell-derived human cardiomyocytes (CMs) represent the most promising source for cardiac cell therapy. In order to sustain attachment, spreading, and orientation of human CMs on a scaffold we exploited an innovative negative replica patterning based on electrophoretic deposition to realize multi-scale micro-structured chitosan-collagen (C/C) scaffolds. Specific patterns were micro-structured on the cathode titanium disks using a laser machine. Cubic and hexagonal patterns were deeply characterized, and reproduced on the surface of the C/C scaffold. We initially challenged different blend with spontaneous contracting neonatal rat CMs to identificate the best substratum, finding that C/C 5:1 proportion can better sustain this type of culture. Finally, human CMs derived from induced pluripotent stem cells were seeded on these patterned scaffolds and colonization of the substrate was observed, thus confirming the validity of the chosen biomaterial. Moreover, preliminary experiments demonstrate the effectiveness of the pattern in controlling the orientation of human CMs. In conclusion, we designed and fabricated a scaffold that allows the attachment, spreading, and orientation of human CMs due to a correct C/C blend composition, to an innovative manufacturing process, and to an effective 3D architecture of the patterns. These data will surely help in solving the quest for a cardiac clinical patch

Assessment of congenital coronary artery fistulas by transesophageal color Doppler echocardiography

PURPOSE: Coronary angiography is the gold standard for imaging the coronary tree, but the relation of coronary artery fistulas to other structures, and their origin and course, may not be apparent. We evaluated the ability of multiplane color Doppler transesophageal echocardiography to identify coronary fistulas. PATIENTS AND METHODS: Twenty-one patients with angiographically confirmed coronary artery fistulas were investigated by transesophageal echocardiography in four Italian hospitals between January 1997 and May 2001. RESULTS: Transesophageal echocardiography correctly diagnosed fistulous connection in all 21 patients. This included 6 patients with connections from the left circumflex artery (into the right chambers of the heart in 5 patients, and into the left ventricle in 1 patient), 10 patients with a fistula arising from the left anterior descending artery or left main coronary artery (with drainage into the right ventricle or main pulmonary artery), and 5 patients with a fistula from the right coronary artery (with drainage sites in the lateral aspect of the right ventricle, the low posterior right atrium, or the superior vena cava). In 4 of the 21 patients, angiography did not identify the precise site of a fistula into the coronary sinus or right ventricle. CONCLUSION: Color Doppler transesophageal echocardiography is useful in the diagnosis and in the precise localization of coronary artery fistulas

Silk fibroin microgels as a platform for cell microencapsulation

: Cell microencapsulation has been utilized for years as a means of cell shielding from the external environment while facilitating the transport of gases, general metabolites, and secretory bioactive molecules at once. In this light, hydrogels may support the structural integrity and functionality of encapsulated biologics whereas ensuring cell viability and function and releasing potential therapeutic factors once in situ. In this work, we describe a straightforward strategy to fabricate silk fibroin (SF) microgels (µgels) and encapsulate cells into them. SF µgels (size ≈ 200 µm) were obtained through ultrasonication-induced gelation of SF in a water-oil emulsion phase. A thorough physicochemical (SEM analysis, and FT-IR) and mechanical (microindentation tests) characterization of SF µgels were carried out to assess their nanostructure, porosity, and stiffness. SF µgels were used to encapsulate and culture L929 and primary myoblasts. Interestingly, SF µgels showed a selective release of relatively small proteins (e.g., VEGF, molecular weight, MW = 40 kDa) by the encapsulated primary myoblasts, while bigger (macro)molecules (MW = 160 kDa) were hampered to diffusing through the µgels. This article provided the groundwork to expand the use of SF hydrogels into a versatile platform for encapsulating relevant cells able to release paracrine factors potentially regulating tissue and/or organ functions, thus promoting their regeneration

Effects of the equilibrium atmosphere on Taleggio cheese storage in micro perforated packaging

Taleggio is an Italian smear-ripened cheese, whose complex microbiota demands the optimisation of the pack-aging system to avoid excessive changes during storage. Metabolic processes of the cheese rind microbiota can be usefully exploited in equilibrium modified atmosphere packaging (EMAP) by balancing microbiota respiration and film permeation. Here, we present the application of three different micro perforated EMAPs as models for smear-ripened cheese compared to two control packaging configurations. Analyses of the main microbial groups, headspace gas, textural profile, and sensory properties were performed to find the best packaging for storage. Results showed that two of the alternative micro perforated packaging systems were able to control the excessive changes during storage, thus limiting fungal overgrowth and allowing the typical development of smear microbiota with minor changes to hardness and cohesiveness. Finally, the sensory evaluation positively favoured one of the alternatively packed cheeses based on its compactness, typical dairy traits, and minor off-flavours. These findings showed that EMAP can be a valid alternative solution to control the storage of Taleggio cheese. Further studies could be conducted to evaluate this system on other smear cheeses