Physicochemical and rheological characterization of a novel hydrocolloid extracted from Althaea officinalis root

Althaea officinalis L. root polysaccharide (AOP) was extracted, and its physicochemical and rheological properties were investigated. Gel permeation chromatography results showed that the molecular weight was 1560 kDa. High-performance liquid chromatography indicated that it was an acidic heteropolysaccharide consisting of five types of monosaccharides including galacturonic acid (40.2%), rhamnose (31.7%), glucose (13.68%), galactose (9.07%), and arabinose (5.35%). The intrinsic viscosity value for AOP in deionized water was 9.4 dl g−1. The AOP solutions at different concentrations (0.5%, 1%, 2%, and 3% w/v), showed shear-thinning behavior, and the apparent viscosity decreased in the presence of different concentrations of NaCl and at different pHs. The frequency sweep test showed the AOP solutions at concentrations less than 0.5% and above 1% exhibited viscous and weak gel behavior, respectively. Since the hysteresis phenomenon was observed in the temperature sweep test of 2% AOP solution, it can be considered as a thermal irreversible gel during the heating and cooling proces

Single polymer laminate composites by compression molding of knitted textiles and microparticles of polyamide 6: Preparation and structure-properties relationship

Knitted reinforced single polymer laminate composites based on polyamide 6 (KSPCsPA6) were produced bycompression molding of polyamide 6 microparticlesMPs()PA6powder-coating annealed PA6 Rib or Jersey knittedtextile structures. TheMPsPA6were synthesized by solution/precipitation activated anionic ring-opening poly-merization ofε-caprolactam. The tensile properties ofKSPCsPA6were studied in relation to the knitted re-inforcement architecture,fiber volume fraction, ply orientation and stacking orders. The tensile stiffness andstrength of the newly preparedKSPCsPA6withfiber content of 15% showed significant improvements as com-pared to the neat anionic PA6 matrix and to commercial hydrolytic PA6 (HPA6). The mechanical behavior of theKSPCsPA6was correlated with the geometry parameters of the knitted reinforcements, the polymorph content ofthe samples and their crystallinity indexes determined by differential scanning calorimetry and wide-angle X-raydiffraction. The fracture behavior of KSPCsPA6was investigated by electron microscopy complemented by si-mulation studies.All authors gratefully acknowledge the support of the project TSSiPRO-NORTE-01-0145-FEDER-000015 funded by the regional operational program NORTE 2020, under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund. This work was partially financed by FEDER funds through the Competitiy Factors Operational Program - COMPETE and by national funds through FCT – Foundation for Science and Technology within the project POCI-01-0145-FEDER-007136. SDT thanks FCT for his PhD Grant SFRH/BD/94759/2013. NVD thanks for the financial support of FCT through the strategic projects LA25/2013-2014 and UID/CTM/50025/2013. Finally, ZZD is thankful to FCT for the SFRH/BSAB/130271/2017 personal research grant

Effects of base fabric parameters on the electro-mechanical behavior of piezoresistive knitted sensors

Strain sensors embedded into fabric structure are one of the most interesting research areas for health and engineering monitoring. In this paper, a textile-based strain sensor has been developed using an intrinsically conductive stainless steel-polyester plain knitted fabric. The influence of fabric structural parameters, such as loop length on electromechanical properties of sensors was studied under a tensile fatigue set. Knitted fabric structure deformation during tensile fatigue was monitored and image processed. Peak fitting of electric resistant waveforms (ERWs) and tensile fatigue versus time were performed to analyze the ERWs behavior in detail wherein the entire elongation of knit strain sensor partitioned into two distinct phases, such as loop head and loop leg sections. The results evidenced a discrepancy between loop head and loop leg elongation rate at the stretching onset and end of relaxing phase. The ERW with the higher resolution was obtained using the longest loop length along with the higher extension.This work was supported in part by FEDER through the COMPETE Program and in part by national funds through Portuguese Foundation for Science and Technology (FCT) under Project POCI-01-0145-FEDER- 007136 and Project UID/CTM/00264. The work of S. D. Tohidi was supported by the FCT under Grant SFRH/BD/94759/2013. The work of A. Zille was supported by FCT under Contract IF/00071/2015. The associate editor coordinating the review of this paper and approving it for publication was Prof. Tarikul Islam.info:eu-repo/semantics/publishedVersio

Microstructural-mechanical properties relationship in single polymer laminate composites based on polyamide 6

This paper studies theflexural and the impact properties of polyamide 6-based knitted reinforced single polymercomposites (KSPCs) prepared by compression molding of powder-coated textile structures. To prepare matrixcomponent, polyamide 6 microparticles (MPs) were synthesized by activated anionic ring-opening poly-merization ofε-caprolactam in solution and then used for powder-coating of the knitted structures. The influenceof the reinforcements' architecture, plies orientation, stacking order andfiber content on thefinal mechanicalproperties of KSPCs were investigated. Rib1 × 1 and Jersey knitted structures were selected as reinforcementsand treated by a stretching-annealing procedure to modify their mechanical properties. The anisotropic tensileand compression properties imparted by the knitted structures were found to be the major factors determiningthe impact andflexural behavior of KSPCs. Moreover, reinforcement's crossover points, the plies orientation andthe presence of a transcrystalline layer at the matrix-reinforcement interface were identified as relevant para-meters. The fracture mechanism of KSPCs was linked to the morphology and crystalline structure of the resultingcomposites and investigated by simulation andfinite element analysis of knitted reinforcemenents.This work was partially financed by FEDER funds through the COMPETE program and by national funds through FCT – Foundation for Science and Technology within the project POCI-01-0145-FEDER 007136. SDT thanks FCT for his Ph.D. Grant SFRH/BD/94759/2013. NVD thanks for the financial support of FCT in the frames of the stra tegic project UID/CTM/50025/2013. Finally, ZZD is thankful to FCT for the SFRH/BSAB/130271/2017 personal research grant. All authors gratefully acknowledge the support of the project TSSiPRO-NORTE-01-0145-FEDER-000015 funded by the regional operational program NORTE 2020, under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund

Micromechanical finite element parametric study of polyamide 6 based single polymer composites reinforced by woven textile structures

This study presents a finite element-based micromechanical analysis of woven single polymer composites (WSPC), prepared by compression molding from polyamide 6 (PA6) woven fabrics powder-coated with PA6 microparticles. Initially, the PA6 microparticles (MP) were synthesized by solution/precipitation activated anionic ring-opening polymerization of ε-caprolactam. After the powder coating, the MP fraction upon each textile ply was transformed into the continuous PA6 matrix by hot pressing at a temperature lower than the melting of the PA6 textile reinforcements. Plain and satin PA6 woven fabrics were selected as reinforcements that were stretched and annealed prior to molding so as to enhance their mechanical performance. The tensile and Izod impact properties of WSPC were characterized in relation to the reinforcement architecture, fiber content and ply orientation. Finite element analysis was used for a parametric study of woven reinforcements and to correlate the deformation and stress distribution of the structures with the tensile failure of the composites. Moreover, to assess the interfacial matrix-reinforcements bonding state, a study of the surfaces fracture, obtained by SEM topography, using image processing was performed.This work was partially financed by FEDER funds through the COMPETE program and by national funds through FCT – Foundation for Science and Technology within the project POCI-01-0145-FEDER007136. SDT thanks FCT for his PhD Grant SFRH/BD/94759/2013. NVD thanks for the financial support of FCT through the strategic project UID/CTM/50025/2013. ZZD is thankful to FCT for the SFRH/BSAB/130271/2017 personal research grant. All authors acknowledge the support of the project TSSiPRO-NORTE-01-0145-FEDER-000015 funded by the regional operational program NORTE 2020, under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund

Comparative structural and mechanical studies on polyamide 6 knitted-reinforced single polymer composites prepared by different reactive processing techniques

Single polymer laminate composites based on anionic polyamide 6 (PA6) matrix-reinforced by PA6 knitted textile structures (KSPC) were produced by nylon reactive injection molding and powder coating/compression molding (PCCM) processing techniques. The effect of the reinforcement’s structure and the fiber volume fraction on the mechanical properties of the knitted-reinforced PA6 composites resulting from the two methods were investigated and compared. The morphology and the crystalline structure of KSPC materials were studied to identify the main factors determining the tensile properties. The results showed that the PCCM method produced laminate composites with higher Young’s modulus and mechanical strength in tension. Microscopy, differential scanning calorimetry and X-ray diffraction experiments were carried out to correlate the morphology and crystalline structure of the composites and their precursors with the different tensile behavior of KSPC prepared using the two techniques. The microscopy and X-ray scattering studies suggested the formation of a transcrystalline layer at the matrix/reinforcement interface. POLYM. COMPOS., 40:E886–E897, 2019. © 2018 Society of Plastics EngineersThis work was partially financed by FEDER funds through the COMPETE program and by national funds through FCT – Foundation for Science and Technology within the project POCI‐01‐0145‐FEDER‐007136. SDT thanks FCT for his PhD Grant SFRH/BD/94759/2013. NVD thanks for the financial support of FCT in the frames of the strategic project UID/CTM/50025/2013. Finally, ZZD is thankful to FCT for the SFRH/BSAB/130271/2017 personal research grant. All authors gratefully acknowledge the support of the project TSSiPRO‐NORTE‐01‐0145‐FEDER‐000015 funded by the regional operational program NORTE 2020, under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund

Modeling Flame Propagation of Coal Char Particles in Heterogeneous Media

In the present research, combustion of a quiescent coal char particle cloud has been studied in the media with spatially discrete sources by means of numerical approach. A thermal model based on diffusion-controlled regime of coal char particles has been generated in order to estimate the characteristics of flame propagation in heterogeneous media. The model uses discrete heat sources to analyze dust combustion of particles with the diameter of 50 μm. Oxygen and Nitrogen have been considered as the main oxidizer and the inert gas, respectively. Flame propagation speed in various dust and oxygen concentrations has been studied. Flame speed as a function of particle size has been investigated and comparison between cases with and without consideration of radiation effect has been made. Furthermore, minimum ignition energy as a function of dust concentration for different particle sizes has been studied. Results show a reasonable compatibility with the existing experimental data

Independent Evolution of Transcriptional Inactivation on Sex Chromosomes in Birds and Mammals

X chromosome inactivation in eutherian mammals has been thought to be tightly controlled, as expected from a mechanism that compensates for the different dosage of X-borne genes in XX females and XY males. However, many X genes escape inactivation in humans, inactivation of the X in marsupials is partial, and the unrelated sex chromosomes of monotreme mammals have incomplete and gene-specific inactivation of X-linked genes. The bird ZW sex chromosome system represents a third independently evolved amniote sex chromosome system with dosage compensation, albeit partial and gene-specific, via an unknown mechanism (i.e. upregulation of the single Z in females, down regulation of one or both Zs in males, or a combination). We used RNA-fluorescent in situ hybridization (RNA-FISH) to demonstrate, on individual fibroblast cells, inactivation of 11 genes on the chicken Z and 28 genes on the X chromosomes of platypus. Each gene displayed a reproducible frequency of 1Z/1X-active and 2Z/2X-active cells in the homogametic sex. Our results indicate that the probability of inactivation is controlled on a gene-by-gene basis (or small domains) on the chicken Z and platypus X chromosomes. This regulatory mechanism must have been exapted independently to the non-homologous sex chromosomes in birds and mammals in response to an over-expressed Z or X in the homogametic sex, highlighting the universal importance that (at least partial) silencing plays in the evolution on amniote dosage compensation and, therefore, the differentiation of sex chromosomes.This project was supported by an Australian Research Fellowship to PDW (DP0987091) and an Australian Research Council discovery project grant to PDW, JED and JAMG (DP1094868) (http://www.arc.gov.au/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

A cross-species comparison of escape from X inactivation in Eutheria: implications for evolution of X chromosome inactivation

Sex chromosome dosage compensation in both eutherian and marsupial mammals is achieved by X chromosome inactivation (XCI)—transcriptional repression that silences one of the two X chromosomes in the somatic cells of females. We recently used RNA fluorescent in situ hybridization (FISH) to show, in individual nuclei, that marsupial X inactivation (in the absence of XIST) occurs on a gene-by-gene basis, and that escape from inactivation is stochastic and independent of gene location. In the absence of similar data from fibroblast cell lines of eutherian representatives, a meaningful comparison is lacking. We therefore used RNA-FISH to examine XCI in fibroblast cell lines obtained from three distantly related eutherian model species: African savannah elephant (Loxodonta africana), mouse (Mus musculus) and human (Homo sapiens). We show that, unlike the orthologous marsupial X, inactivation of the X conserved region (XCR) in eutherians generally is complete. Two-colour RNA-FISH on female human, mouse and elephant interphase nuclei showed that XCR loci have monoallelic expression in almost all nuclei. However, we found that many loci located in the evolutionarily distinct recently added region (XAR) displayed reproducible locus-specific frequencies of nuclei with either one or two active X alleles. We propose that marsupial XCI retains features of an ancient incomplete silencing mechanism that was augmented by the evolution of the XIST gene that progressively stabilized the eutherian XCR. In contrast, the recently added region of the eutherian X displays an incomplete inactivation profile similar to that observed on the evolutionarily distinct marsupial X and the independently evolved monotreme X chromosomes