Power Law Scaling for a System of Interacting Units with Complex Internal Structure

We study the dynamics of a system composed of interacting units each with a complex internal structure comprising many subunits. We consider the case in which each subunit grows in a multiplicative manner. We propose a model for such systems in which the interaction among the units is treated in a mean field approximation and the interaction among subunits is nonlinear. To test the model, we identify a large data base spanning 20 years, and find that the model correctly predicts a variety of empirical results.Comment: 4 pages with 4 postscript figures (uses Revtex 3.1, Latex2e, multicol.sty, epsf.sty and rotate.sty). Submitted to PR

Sol-gel preparation of a di-ureasil electrolyte doped with lithium perchlorate

Solid polymer electrolytes (SPEs) synthesized by the sol-gel process and designated as ormolytes (organically modified electrolytes), have been prepared through the incorporation of lithium perchlorate, LiClO4 into the U(2000) organic-inorganic hybrid network. Electrolytes with lithium salt compositions of n (where n indicates the number of oxyethylene units per Li+ ion) between ∞ and 0.5 were characterized by conductivity measurements, cyclic voltammetry at a gold microelectrode, thermal analysis and spectroscopic techniques. The conductivity results obtained suggest that this system offers a quite significant improvement over previously characterized analogues doped with lithium triflate.Fundação para a Ciência e a Tecnologia (FCT) - POCI/QUI/59856/2004.Fundação Calouste Gulbenkian - MMS.Universidade do Minho.Universidade de Trás-os-Montes e Alto Douro

Study of sol-gel derived di-ureasils doped with zinc triflate

Prova tipográfica (In Press)A publicar em "Solid States Sciences".Zinc triflate (Zn(CF3SO3)2)-doped sol-gel derived di-urea cross-linked POE/siloxane ormolytes (designated as di-ureasils) with ∞ > n ≥ 1 (where the salt content is expressed as n, the molar ratio of oxyethylene moieties to Zn2+ ions) were investigated. The hybrids with n ≥ 5 are entirely amorphous; those with n > 10 are thermally stable up to approximately 305 ºC. The siliceous network of representative samples (n = 200 and 10) is essentially composed of (SiO)3Si(CH2)- environments and is thus highly branched. The distance between the structural units in samples with 200 ≥ n ≥ 10 and n ≤ 7 is 4.2 and 4.3 Å, respectively. The estimated interdomain distance is 11 and 13 Å for xerogels with 200 ≥ n ≥ 20 and n ≤ 10, respectively. At n = 1 a crystalline POE/Zn(CF3SO3)2 complex of unknown stoichiometry is formed. The conductivity maxima are located at n = 60 (3x10-6 S cm-1) and n = 20 (7x10-5 S cm-1) at 30 and 100 ºC, respectively.Fundação para a Ciência e a Tecnologia - POCTI/P/CTM/46780/03; SFRH/BD/13559/03

Sol-gel derived Li+-doped poly(ε-caprolactone)/siloxane biohybrid electrolytes

Electrolytes based on a poly(ε-caprolactone) (PCL)/siloxane organic/inorganic host framework doped with lithium triflate (LiCF3SO3) were synthesised through the sol-gel process. In this biohybrid matrix short PCL chains are covalently bonded via urethane linkages to the siliceous network. Samples with salt composition n (molar ratio of PCL repeat units per Li+ ion) ranging from ∞ to 0.5 were investigated. All the ormolyte materials analysed are amorphous. Xerogels with n > 0.5 are thermally stable up to about 300°C. The most conducting ormolyte of the series is that with n = 0.5 (1.6×10−7 and 3.2×10−5 Ω−1 cm−1 at 25 and 100°C, respectively). This sample is electrochemically stable between −1 and 6 V versus Li+.Fundação para a Ciência e Tecnologia - POCTI/P/CTM/33653/00, SFRH/BD/13559/03, POCTI/P/CTM/46780/03.Fundação para a Ciência e a Tecnologia (FCT

Psychometric properties of the modified Yale Food Addiction Scale 2.0 in a large Brazilian sample

Objective: The field of food addiction has attracted growing research attention. The modified Yale Food Addiction Scale 2.0 (mYFAS 2.0) is a screening tool based on DSM-5 criteria for substance use disorders. However, there is no validated instrument to assess food addiction. Methods: The mYFAS 2.0 has been transculturally adapted to Brazilian Portuguese. The data for this study was obtained through an anonymous web-based research platform: participants provided socio- demographic data and answered Brazilian versions of the the mYFAS 2.0 and the Barratt Impulsivity Scale (BIS-11). Analysis included an assessment of the Brazilian mYFAS 2.0’s internal consistency reliability, factor structure, and convergent validity in relation to BIS-11 scores. Results: Overall, 7,639 participants were included (71.3% females; age: 27.2 6 7.9 years). The Brazilian mYFAS 2.0 had adequate internal consistency reliability (Cronbach’s alpha = 0.89). A single factor solution yielded the best goodness-of-fit parameters for both the continuous and categorical version of the mYFAS 2.0 in confirmatory factor analysis. In addition, mYFAS 2.0 correlated with BIS-11 total scores (Spearman’s rho = 0.26, p o 0.001) and subscores. Conclusion: The Brazilian mYFAS 2.0 demonstrated adequate psychometric properties in our sample; however, future studies should further evaluate its discriminant validity

Mechanical joining methods for additive manufactured assembly tools

The use of additive manufacturing (AM) processes is growing in the manufacturing industry. One application with great potential for using these processes is the manufacture of assembly tools for a high-ly competitive markets, such as the automotive industry. A critical aspect of the assembly tool design is its capability to incorporate modifications even at a late stage of its development in very short time. In many cases, these modifications are achieved using metal inserts in the polymeric tool, which allow to add new geometric features. This capability increases the usefulness and versatility of components produced by AM and compensate for potential shortcomings of using additive mate-rials. The purpose of this paper is to evaluate the potential use of accessories in additive manufactured com-ponents. In addition, the effect of different percentages of infill tool material on the joining quality of accesso-ries is evaluated. This is done by performing a screw pull-out test on a ABS ESD-7 part, produced by fused deposition modelling. The following different joining solutions were compared and studied in this work: em-bedded inserts, glue, heating processes, pressure (Tap-in) and creation of threads, such as, printing the thread directly and machining the thread onto the material.Programa Operacional Competitividade e Internacionalização - COMPETE 2020, Projeto nº 002814, Ref. POCI-01-0247-FEDER-002814 entre a Univ. do Minho e a Bosc

The shape of ecological networks

We study the statistics of ecosystems with a variable number of co-evolving species. The species interact in two ways: by prey-predator relationships and by direct competition with similar kinds. The interaction coefficients change slowly through successful adaptations and speciations. We treat them as quenched random variables. These interactions determine long-term topological features of the species network, which are found to agree with those of biological systems.Comment: 4 pages, 2 figure

Presentation and validation of a new optical sensing concept based in a 3d-printing solution

In high competitive markets, such as the automotive industry, the better quality of products, reduction of manufacturing costs and the fulfilment of all delivery deadlines can only be achieved through continuous improvement of production capabilities. One current strategy is to develop and create smarter and adaptive assembly tools. Automation is a relevant area of development in the current industrial world and the baseline of the fourth industrial revolution (Industry 4.0). Namely, it is very important to use sensing components on jigs for assembly parts in the production line. The arrangement of sensing components on the assembly tools is very dependent of the product, making the project more complex and less flexible. This issue can penalise the productivity heavily, especially if a wide range of products and changeover operations are usual. The use of Additive Manufacturing (AM) is growing in the industry and offers a high potential for research and development in the present stage. The AM is advantageous in many areas, especially in the rapid construction of complex tools (RP). This paper presents a new optical sensing concept based on the 3D printing of internal circuits in the assembly tools. This solution can bring many advantages and increase tools flexibility.Programa Operacional de Competividade e Internacionalização - COMPETE 2020, Projeto nº 002814; Ref. POCI-01-0247-FEDER-002814, entre a Univ. Minho e a Bosc

Optical Sensor for Diverse Organic Vapors at ppm Concentration Ranges

A broadly responsive optical organic vapor sensor is described that responds to low concentrations of organic vapors without significant interference from water vapor. Responses to several classes of organic vapors are highlighted, and trends within classes are presented. The relationship between molecular properties (vapor pressure, boiling point, polarizability, and refractive index) and sensor response are discussed