Universal Control on Pyroresistive Behavior of Flexible Self‐Regulating Heating Devices

Smart heating devices with reliable self‐regulating performances and high efficiency, combined with additional properties like mechanical flexibility, are of particular interest in healthcare, soft robotics, and smart buildings. Unfortunately, the development of smart heaters necessitates managing normally conflicting requirements such as good self‐regulating capabilities and efficient Joule heating performances. Here, a simple and universal materials design strategy based on a series connection of different conductive polymer composites (CPC) is shown to provide unique control over the pyroresistive properties. Hooke's and Kirchhoff's laws of electrical circuits can simply predict the overall pyroresistive behavior of devices connected in series and/or parallel configurations, hence providing design guidelines. An efficient and mechanically flexible Joule heating device is hence designed and created. The heater is characterized by a zero temperature coefficient of resistance below the self‐regulating temperature, immediately followed by a large and sharp positive temperature coefficient (PTC) behavior with a PTC intensity of around 10⁶. Flexibility and toughness is provided by the selected elastomeric thermoplastic polyurethane (TPU) matrix as well as the device design. The universality of the approach is demonstrated by using different polymer matrices and conductive fillers for which repeatable results are consistently obtained.     

Towards a progressive home-making: the ambivalence of migrants’ experience in a multicultural condominium

Following the rhetoric of globalisation and hyper-mobility, the ideas of placelessness and detachment from place seem to be the essential features of contemporary cities. This conceals the human necessity to constantly create new senses of home and new home-making practices. Starting from ethnographic research in a multicultural condominium (called Hotel House) in Italy, the paper uses the urban experience of migrants to look at different home-making practices by analysing them as multidimensional (spatial, social and emotional) processes. Firstly, migrants living in Hotel House produce ‘home’ by imbuing domestic spaces with their own memory and meaning and creating public and collective spaces characterised by ‘homely relations’. In both cases, they produce material, emotional and symbolic resources. Secondly, the paper analyses the ‘dark side of home-making’, inasmuch as the social density of the home-making practices in Hotel House’s domestic and public spaces also favours strong forms of social control, particularly relevant for women and young people. Thirdly, the paper analyses how the sense of home sustains a collective intercultural mobilisations against Hotel House’s institutional abandonment and stigmatisation that reveal the threshold-crossing capacity of ‘home’. Home, in conclusion, is not a romanticised, fixed and bounded place to protect. It is a plural and conflictual field of action that can support social exclusion but can also open new interconnections and possibilities of peoples’ empowerment.     

Sourdough on quinoa and buckwheat gluten-free breads: Evaluation of autochthonous starter fermentation on bread nutritional and technological properties

The aim of this work was to evaluate the effect of two autochthonous strains of lactic acid bacteria as sourdough (SD) starters on gluten-free bread technological quality and in vitro starch hydrolysis and antioxidant activity. Two strains of Limosilactobacillus fermentum isolated from buckwheat (BW) and quinoa flours were used. SDs were prepared from wholegrain quinoa or BW flours. Bread technological properties, total polyphenol content and in vitro antioxidant activity and starch hydrolysis and dialysability were assessed. Specific bread volumes were between 2.61 and 2.76 cm³ g⁻¹. Breads with quinoa-based SD had overall higher technological quality than breads made with BW SDs, shown by a softer, well-aerated crumb, with an opener crumb structure and larger air area. Crumb firming during storage was reduced up to 29% when quinoa SD was used, and up to 42% when BW SD was added. Quinoa breads showed higher polyphenols and FRAP values, whereas BW breads had significantly higher ABTS values. Total starch hydrolysis and dialysability were significantly reduced when SD was used. Starch hydrolysis was reduced up to 42% and 25% when quinoa and BW SD were used, respectively. SD application produced breads with higher technological quality and modified in vitro starch hydrolysis and antioxidant capacity. Even though these effects seemed to be influenced by pH, a biological effect was also observed.     

Bed Expansion and Particle Classification in Liquid Fluidized Beds with Structured Internals

The inclusion of a structured packing as internal in a liquid‐solid fluidized bed allows expansion of the liquid velocity operation range before elutriation, promoting the liquid solid contact and mixing. The bed expansion of liquid‐solid fluidized beds provided with structured packing as internals is examined, for solids denser than the liquid phase and within a wide range of operating conditions. A correlation to estimate the bed expansion in liquid‐solid fluidized beds using structured packing as internals is developed. In addition, the feasibility of employing structured packing as internals for favoring classification of different density particles is demonstrated by analyzing the mass elutriated from the column at different liquid velocities for single particles or binary mixtures.     

墨西哥制造

<正>Emiliano Godoy生于墨西哥,曾经游学美国和丹麦。他认为制造业要实施可持续发展战略,就必须在设计中注重材料的选择和运用。人们可以从他的设计中看到其对材料和结构的不断尝试。多年来,他     

Effect of thermal annealing on the electrical conductivity of high-strength bicomponent polymer tapes containing carbon nanofillers

A new concept is described that creates highly oriented multifunctional polymer nanocomposite tapes (or fibres) that combine high stiffness and strength with good electrical properties and a low percolation threshold of conductive nanofillers. The concept is based on a bicomponent construction consisting of a highly oriented polymer core together with conductive polymer composite skins based on a polymer with lower melting temperature than the core. This construction allows for a thermal annealing process that can be applied selectively to the skins to improve their conductivity through a kinetic re-aggregation process while retaining the mechanical properties of the core and hence those of the overall tape or fibre. In the current study this generic concept was applied to bicomponent tapes based on a polypropylene homopolymer core and a multi-wall carbon nanotube or carbon black filled polypropylene copolymer skin. The conductivity of the bicomponent tape containing 5.3 wt.% of MWNTs in its outer skins increased from 1.3E?6 to 1.5 S/cm after annealing while the percolation threshold in the copolymer skins of highly drawn bicomponent tapes could be decreased from 5.3 to 1.1 wt.%. To the best of the authors’ knowledge this is the lowest percolation threshold reported in literature for highly drawn polymer nanocomposites fibres or tapes. In fact, the percolation threshold is as low as 0.1 wt.% when considered on the overall tape as the conductive skins account for only 10% of the total volume of these bicomponent tapes.     

Synthesis of amorphous silicon/magnesia based direct opals with tunable optical properties

The effective refractive index of silica based artificial opals can be strongly modulated through magnesiothermic and wet etching processes. The magnesiothermic reduction of silica spheres assembled in a fcc lattice produces amorphous silicon/magnesia matrix, which can be easily converted in oxidized porous silicon, preserving the ordered structure. These results are verified by electron microscopies and IR/Raman spectroscopies. The optical properties are analyzed in terms of the experimental reflectance spectra. By comparing the measured data to rigorous calculations, the good quality of the opaline replicas is demonstrated.     

Calcium‐phosphate and parathyroid intradialytic profiles: A potential aid for tailoring the dialysate calcium content of patients on different hemodialysis schedules

Severe hyperparathyroidism is a challenge on hemodialysis. The definition of dialysate calcium (Ca) is a pending issue with renewed importance in cases of individualized dialysis schedules and of portable home dialysis machines with low‐flow dialysate. Direct measurement of calcium mass transfer is complex and is imprecisely reflected by differences in start‐to‐end of dialysis Ca levels. The study was performed in a dialysis unit dedicated to home hemodialysis and to critical patients with wide use of daily and tailored schedules. The Ca‐phosphate (P)‐parathyroid hormone (PTH) profile includes creatinine, urea, total and ionized Ca, albumin, sodium, potassium, P, PTH levels at start, mid, and end of dialysis. “Severe” secondary hyperparathyroidism was defined as PTH > 300 pg/mL for ≥3 months. Four schedules were tested: conventional dialysis (polysulfone dialyzer 1.8–2.1 m²), with dialysate Ca 1.5 or 1.75 mmol/L, NxStage (Ca 1.5 mmol/L), and NxStage plus intradialytic Ca infusion. Dosages of vitamin D, calcium, phosphate binders, and Ca mimetic agents were adjusted monthly. Eighty Ca‐P‐PTH profiles were collected in 12 patients. Serum phosphate was efficiently reduced by all techniques. No differences in start‐to‐end PTH and Ca levels on dialysis were observed in patients with PTH levels < 300 pg/mL. Conversely, Ca levels in “severe” secondary hyperparathyroid patients significantly increased and PTH decreased during dialysis on all schedules except on Nxstage (P < 0.05). Our data support the need for tailored dialysate Ca content, even on “low‐flow” daily home dialysis, in “severe” secondary hyperparathyroid patients in order to increase the therapeutic potentials of the new dialysis techniques.