Nonextensive Thermostatistics and the HH-Theorem Revisited

In this paper we present a new derivation of the $H$-theorem and the corresponding collisional equilibrium velocity distributions, within the framework of Tsallis' nonextensive thermostatistics. Unlike previous works, in our derivation we do not assume any modification on the functional form of Boltzmann's original "molecular chaos hypothesis". Rather, we explicitly introduce into the collision scenario, the existence of statistical dependence between the molecules before the collision has taken place, through a conditional distribution $f(\vec{v}_2|\vec{v}_1)$. In this approach, different equilibrium scenarios emerge depending on the value of the nonextensive entropic parameter.Comment: 6 pages, 1 figure, to appear in Physica

The Latin Leaflet

In the present work, we apply the asymptotic homogenization technique to the equations describing the dynamics of a heterogeneous material with evolving micro-structure, thereby obtaining a set of upscaled, effective equations. We consider the case in which the heterogeneous body comprises two hyperelastic materials and we assume that the evolution of their micro-structure occurs through the development of plastic-like distortions, the latter ones being accounted for by means of the Bilby–Kröner–Lee (BKL) decomposition. The asymptotic homogenization approach is applied simultaneously to the linear momentum balance law of the body and to the evolution law for the plastic-like distortions. Such evolution law models a stress-driven production of inelastic distortions, and stems from phenomenological observations done on cellular aggregates. The whole study is also framed within the limit of small elastic distortions, and provides a robust framework that can be readily generalized to growth and remodeling of nonlinear composites. Finally, we complete our theoretical model by performing numerical simulations

Escherichia coli expression and purification of LL37 fused to a family III carbohydrate-binding module from Clostridium thermocellum

The cathelicidin derived human peptide LL37 has a broad spectrum of antimicrobial and immunomodulatory activities. The large variety of biological activities makes LL37 a very promising candidate for clinical applications. The production of biologically active LL37 in large amounts with reduced costs can only be achieved using recombinant techniques. In this work, LL37 has been cloned to the N- and C-termini of a family III carbohydrate-binding module fused to the linker sequence (LK-CBM3) from Clostridium thermocellum; both constructions (LL37-LK-CBM3 and LK-CBM3-LL37) were cloned into the pET-21a vector. A formic acid recognition site was introduced between the two modules, allowing the isolation of LL37 after chemical cleavage. The recombinant proteins were expressed in Escherichia coli BL21 (DE3) and solubilized with Triton X-100. The purification was achieved using cellulose CF11 fibers, taking advantage of the CBM3 specific affinity for cellulose; after hydrolysis with formic acid, LL37 was further purified by reverse-phase HPLC, as confirmed by MALDI-TOF mass spectrometry. The production and purification methodology developed in this work compares advantageously to other protocols previously described, having fewer purification steps. Only the recombinant LL37 obtained from the C-terminally fused protein (LK-CBM3-LL37) showed antibacterial activity against E. coli K12, with a MIC of 180 μg/ml.University of Porto. Institute of Molecular Pathology and Immunology. Proteomics Unit (IPATIMUP)Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BD/27404/200

LL37, a human antimicrobial peptide with immunomodulatory properties

Cationic antimicrobial peptides (AMPs) represent the first line of defense against many invading pathogens. These small amphipathic peptides are part of the innate immune system and have a broad-spectrum activity against bacteria, fungi and viruses. In mammals, at least two distinct groups of AMPs are found. Defensins are the more representatives and cathelicidins form the second group. The hCAP18/LL37 is the only known human cathelicidin. The antimicrobial peptide is referred to as LL37, since it has a 37 amino acids sequence starting with two leucines. It is a 4.5 kDa, cationic (+6), amphipathic -helical peptide, with a broad spectrum of antimicrobial activity. Besides its antimicrobial properties LL37 plays a central role in innate immune responses and inflammation. It has been identified as a potent chemoattractant for mast cells, monocytes, T lymphocytes and neutrophils using formyl-peptide receptorlike 1 (FPRL1). LL37 also promotes wound healing, angiogenesis and arteriogenesis and acts as immune adjuvant.y FEDER funds through the Programa Operacional Factores de Competitividade – COMPETE and by national funds through the project PTDC/EDB/EBI/112170/2009 from the Fundação para a Ciência e Tecn

Value-at-Risk and Tsallis statistics: risk analysis of the aerospace sector

In this study, we analyze the aerospace stocks prices in order to characterize the sector behavior. The data analyzed cover the period from January 1987 to April 1999. We present a new index for the aerospace sector and we investigate the statistical characteristics of this index. Our results show that this index is well described by Tsallis distribution. We explore this result and modify the standard Value-at-Risk (VaR), financial risk assessment methodology in order to reflect an asset which obeys Tsallis non-extensive statistics.Comment: 10 pages, 4 figures, 1 table, to appear in Physica

Homogenized out-of-plane shear response three-scale fiber-reinforced composites

In the present work we embrace a three scales asymptotic homogenization approach to investigate the effective behavior of hierarchical linear elastic composites reinforced by cylindrical, uniaxially aligned fibers and possessing a periodic structure at each hierarchical level of organization. We present our novel results assuming isotropy of the constituents and focusing on the effective out-of-plane shear modulus, which is computed exploiting the solution of the arising anti-plane problems. The latter are solved semi-analytically by means of complex variables and successfully benchmarked against the results obtained by finite elements. Our findings can pave the way for multiscale modeling of complex hierarchical materials (such as bone and tendons) at a negligible computational cost

New hydrogel obtained by chitosan and dextrin-VA co-polymerization

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Three scales asymptotic homogenization and its application to layered hierarchical hard tissues

In the present work a novel multiple scales asymptotic homogenization approach is proposed to study the effective properties of hierarchical composites with periodic structure at different length scales. The method is exemplified by solving a linear elastic problem for a composite material with layered hierarchical structure. We recover classical results of two-scale and reiterated homogenization as particular cases of our formulation. The analytical effective coefficients for two phase layered composites with two structural levels of hierarchy are also derived. The method is finally applied to investigate the effective mechanical properties of a single osteon, revealing its practical applicability in the context of biomechanical and engineering applications

Textile depilling : superior finishing using cellulose-binding domains with residual enzymatic activity

Textile fabric depilling is an important industrial application of cellulases. The depilling effect and achievement of desirable touch properties are among the applications sought by users. This process, although effective, is associated with significant tensile strength loss. The depilling mechanism is still a subject of controversy. In this work, we introduce a new perspective in understanding of the depilling mechanism, specifically we consider the contribution of interfacial properties. Cellulose Binding Domains (CBDs) obtained by ultrafiltration after digestion with a protease, were used in depilling experiments. Compared with cellulose, the performance of CBDs was very positive. In fact, when using CBD with residual hydrolytic activity, it was possible to achieve superior depilling treatments