Bifurcation and stability analysis of a two step model for monitoring anaerobic digestion processes

This paper deals with the equilibria and stability analysis of the two step anaerobic model initially proposed by [12] to describe the dynamical behavior of an anaerobic fixed-bed wastewater treatment process. In a first part, the model is analyzed: its equilibria and their stability are established considering qualitative properties of the kinetics. In a second part, it is shown that the overloading tolerance (denoted herein OT), a parameter proposed in [9] to monitor anaerobic processes on-line, may not be suitable for monitoring the system and even causes serious problems under certain functioning conditions. Based on the analysis results established in the first part, a modified OT is proposed and evaluated in simulation

Thermal properties comparison of hybrid CF/FF and BF/FF cyanate ester-based composites

[EN] Insights within thermal expansion, conductivity, and decomposition dependencies with temperature on symmetrical and unsymmetrical layered carbon (CF) or basalt (BF) fabrics in combination with flax fibers (FF) were approached. Driven by commercial application and environmental concerns, the paper draws attention on a modified formula of cyanate ester with a common epoxy resin under an optimized ratio of 70:30 (vol%) as well as on the hybrid reinforcements stacking sequences. Synergetic effects were debated in terms of the CF and BF stacking sequences and corresponding volume fraction followed by comparisons with values predicted by the deployment of hybrid mixtures rules (RoHM/iRoHM). CF hybrid architectures revealed enhanced effective thermophysical properties over their BF counterparts and both over the FF-reinforced polymer composite considered as a reference. Thermal conductivities spread between 0.116 and 0.299 W m-1 K-1 from room temperature up to 250 C on all hybrid specimens, giving rise to an insulator character. Concerning the coefficient of thermal expansion, CF hybrid architectures disclosed values of 1.236 10-6 K-1 and 3.102 10-6 K-1 compared with BF affine exhibiting 4.794 10-6 K-1 and 6.245 10-6 K-1, respectively, with an increase in their volume fraction.The corresponding author gratefully acknowledges the financial assistance of German Academic Exchange Service-DAAD that enabled and supported the internship with Fraunhofer Research Institution for Polymeric Materials and Composites-PYCO, Germany. Many thanks go to Dr. Christian Dreyer and Dr. Maciej Gwiazda for the resin formula and access to the composite manufacturing technology.Motoc, DL.; Ferrándiz Bou, S.; Balart, R. (2018). Thermal properties comparison of hybrid CF/FF and BF/FF cyanate ester-based composites. Journal of Thermal Analysis and Calorimetry. 133(1):509-518. https://doi.org/10.1007/s10973-018-7222-yS5095181331Assarar M, Zouari W, Sabhi H, Ayad R, Berthelot J-M. Evaluation of the damping of hybrid carbon–flax reinforced composites. Compos Struct. 2015;132:148–54.Duc F, Bourban PE, Plummer CJG, Månson JAE. Damping of thermoset and thermoplastic flax fibre composites. Compos A Appl Sci Manuf. 2014;64:115–23.Saba N, Jawaid M, Alothman OY, Paridah MT. A review on dynamic mechanical properties of natural fibre reinforced polymer composites. Constr Build Mater. 2016;106:149–59.Tian H, Zhang S, Ge X, Xiang A. Crystallization behaviors and mechanical properties of carbon fiber-reinforced polypropylene composites. J Therm Anal Calorim. 2017;128(3):1495–504.Alvarez V, Rodriguez E, Vázquez A. Thermaldegradation and decomposition of jute/vinylester composites. J Therm Anal Calorim. 2006;85(2):383–9.Manfredi LB, Rodríguez ES, Wladyka-Przybylak M, Vázquez A. Thermal degradation and fire resistance of unsaturated polyester, modified acrylic resins and their composites with natural fibres. Polym Degrad Stab. 2006;91(2):255–61.Lazko J, Landercy N, Laoutid F, Dangreau L, Huguet MH, Talon O. Flame retardant treatments of insulating agro-materials from flax short fibres. Polym Degrad Stab. 2013;98(5):1043–51.Bar M, Alagirusamy R, Das A. Flame retardant polymer composites. Fibers Polym. 2015;16(4):705–17.Kollia E, Loutas T, Fiamegkou E, Vavouliotis A, Kostopoulos V. Degradation behavior of glass fiber reinforced cyanate ester composites under hydrothermal ageing. Polym Degrad Stab. 2015;121:200–7.Jawaid M, Abdul Khalil HPS. Cellulosic/synthetic fibre reinforced polymer hybrid composites: a review. Carbohyd Polym. 2011;86(1):1–18.Azwa ZN, Yousif BF, Manalo AC, Karunasena W. A review on the degradability of polymeric composites based on natural fibres. Mater Des. 2013;47:424–42.H-y Cheung, M-p Ho, K-t Lau, Cardona F, Hui D. Natural fibre-reinforced composites for bioengineering and environmental engineering applications. Compos B Eng. 2009;40(7):655–63.Dittenber DB, GangaRao HVS. Critical review of recent publications on use of natural composites in infrastructure. Compos A Appl Sci Manuf. 2012;43(8):1419–29.Faruk O, Bledzki AK, Fink H-P, Sain M. Biocomposites reinforced with natural fibers: 2000–2010. Prog Polym Sci. 2012;37(11):1552–96.Praveen RS, Jacob S, Murthy CRL, Balachandran P, Rao YVKS. Hybridization of carbon–glass epoxy composites: an approach to achieve low coefficient of thermal expansion at cryogenic temperatures. Cryogenics. 2011;51(2):95–104.Jawaid M, Abdul Khalil HPS, Alattas OS. Woven hybrid biocomposites: dynamic mechanical and thermal properties. Compos A Appl Sci Manuf. 2012;43(2):288–93.Swolfs Y, Gorbatikh L, Verpoest I. Fibre hybridisation in polymer composites: a review. Compos A Appl Sci Manuf. 2014;67:181–200.Rojo E, Alonso MV, Oliet M, Del Saz-Orozco B, Rodriguez F. Effect of fiber loading on the properties of treated cellulose fiber-reinforced phenolic composites. Compos B Eng. 2015;68:185–92.LeGault M. Natural fiber composites: market share, one part at the time. Compos World. 2016;5(2):68–75.Joshi SV, Drzal LT, Mohanty AK, Arora S. Are natural fiber composites environmentally superior to glass fiber reinforced composites? Compos A Appl Sci Manuf. 2004;35(3):371–6.Wambua P, Ivens J, Verpoest I. Natural fibres: can they replace glass in fibre reinforced plastics? Compos Sci Technol. 2003;63(9):1259–64.Bertomeu D, García-Sanoguera D, Fenollar O, Boronat T, Balart R. Use of eco-friendly epoxy resins from renewable resources as potential substitutes of petrochemical epoxy resins for ambient cured composites with flax reinforcements. Polym Compos. 2012;33(5):683–92.Alam M, Akram D, Sharmin E, Zafar F, Ahmad S. Vegetable oil based eco-friendly coating materials: a review article. Arab J Chem. 2014;7(4):469–79.Bakare FO, Ramamoorthy SK, Åkesson D, Skrifvars M. Thermomechanical properties of bio-based composites made from a lactic acid thermoset resin and flax and flax/basalt fibre reinforcements. Compos A Appl Sci Manuf. 2016;83:176–84.Pardauil JJR, de Molfetta FA, Braga M, de Souza LKC, Filho GNR, Zamian JR, et al. Characterization, thermal properties and phase transitions of amazonian vegetable oils. J Therm Anal Calorim. 2017;127(2):1221–9.Głowińska E, Datta J, Parcheta P. Effect of sisal fiber filler on thermal properties of bio-based polyurethane composites. J Therm Anal Calorim. 2017;130(1):113–22.Mosiewicki MA, Aranguren MI. A short review on novel biocomposites based on plant oil precursors. Eur Polym J. 2013;49(6):1243–56.Lligadas G, Ronda JC, Galià M, Cádiz V. Renewable polymeric materials from vegetable oils: a perspective. Mater Today. 2013;16(9):337–43.Fombuena V, Sanchez-Nacher L, Samper MD, Juarez D, Balart R. Study of the properties of thermoset materials derived from epoxidized soybean oil and protein fillers. J Am Oil Chem Soc. 2013;90(3):449–57.Pil L, Bensadoun F, Pariset J, Verpoest I. Why are designers fascinated by flax and hemp fibre composites? Compos A Appl Sci Manuf. 2016;83:193–205.Wooster TJ, Abrol S, Hey JM, MacFarlane DR. Thermal, mechanical, and conductivity properties of cyanate ester composites. Compos A Appl Sci Manuf. 2004;35(1):75–82.Mallarino S, Chailan JF, Vernet JL. Glass fibre sizing effect on dynamic mechanical properties of cyanate ester composites I. Single frequency investigations. Eur Polym J. 2005;41(8):1804–11.Sothje D, Dreyer C, Bauer M, editors. Advanced possibilities in thermoset recycling. In: The 3rd international conference on thermosets. 2013; Berlin, Germany.Yuan L, Huang S, Gu A, Liang G, Chen F, Hu Y, et al. A cyanate ester/microcapsule system with low cure temperature and self-healing capacity. Compos Sci Technol. 2013;87:111–7.Czigány T. Special manufacturing and characteristics of basalt fiber reinforced hybrid polypropylene composites: mechanical properties and acoustic emission study. Compos Sci Technol. 2006;66(16):3210–20.Marom G, Fischer S, Tuler FR, Wagner HD. Hybrid effects in composites: conditions for positive or negative effects versus rule-of-mixtures behaviour. J Mater Sci. 1978;13(7):1419–26.Torquato S. Random heterogeneous materials: microstructure and macroscopic properties. New York: Springer; 2002.Cherki A-B, Remy B, Khabbazi A, Jannot Y, Baillis D. Experimental thermal properties characterization of insulating cork–gypsum composite. Constr Build Mater. 2014;54:202–9.Bismarck A, Aranberri-Askargorta I, Springer J, Lampke T, Wielage B, Stamboulis A, et al. Surface characterization of flax, hemp and cellulose fibers; Surface properties and the water uptake behavior. Polym Compos. 2002;23(5):872–94.Motoc Luca D, Ferrandiz Bou S, Balart Gimeno R. Effects of fibre orientation and content on the mechanical, dynamic mechanical and thermal expansion properties of multi-layered glass/carbon fibre-reinforced polymer composites. J Compos Mater. 2014;49(10):1211–1221.CES EduPack. Granta Design; 2013.Monteiro SN, Calado V, Rodriguez RJS, Margem FM. Thermogravimetric behavior of natural fibers reinforced polymer composites—An overview. Mater Sci Eng, A. 2012;557:17–28

Increased epithelial cell proliferation in the ileal pouch mucosa of patients with familial adenomatous polyposis

To eliminate the risk of colorectal cancer in patients with familial adenomatous polyposis (FAP), reconstructive proctocolectomy is performed. Although most colonic mucosa is resected during the ileal pouch anal anastomosis, adenomas and carcinomas may develop in the pouch. This may be caused by altered cell kinetics due to intraluminal changes in the pouch. In 32 patients with FAP, biopsy specimens from the mucosa of the pouch and also of the afferent ileal loop were taken. Tissue sections were immunohistochemically processed with the monoclonal antibodies M30 and MIB-1 to assess apoptotic and proliferative indices, respectively. Cell proliferation was also assessed by a modified sign test. There were no significant differences in apoptotic rates between the mucosa of the pouch and the mucosa of the afferent ileal loop. However, cell proliferation was significantly higher in the mucosa of the pouch vs afferent ileal loop, both by using the quantitative (68.3% vs 61.6%, p = 0.001) and semiquantitative methods (p < 0.05). Our newly developed semiquantitative approach outperformed previously described methods. The higher cell proliferation in the pouch as compared to the afferent ileal loop may contribute to the increased risk for adenomas and carcinomas in the pouch of patients with FAP and emphasizes the need for regular endoscopic surveillance

“Help! I Need Somebody”: Music as a global resource for obtaining wellbeing goals in times of crisis

Health and self-regulatio

Interaction management between social agents and human

In this paper we address the problem of managing social interactions between a human user and a set of social agents in structured environments. These agents have to regulate a measurable characteristic of the user. Our study focuses mainly therapeutic, caring for elderly people and assessment applications. The agent concept considered in this study is suitable for multi-robot systems (physical, service, mobile or not), but also to virtual agents (avatars) in a virtual reality (VR) application. The proposed approach has been adapted for an application of social phobia treatment using virtual reality. Thus, we conducted a case study to show the effectiveness of our contribution

Towards a systematic approach to reduce complex bioprocess models - Application to the ADM1

A mathematical reduction method named Homotopy is applied to the Anaerobic Digestion Model No. 1 or ADM1, cf. (Batstone et al., 2002), a complex model of bioprocess describing the anaerobic digestion. Because we are interested in what happens on small timescales, the proposed method neglects the slow dynamics keeping only the fastest ones in using the technique of eigenvalue-state association. This transformation is described by the Homotopy matrix H. Simulations show that the reduced model behaves globally like the initial model at steady states. This approach is confronted with the reduction method using balancing of empirical gramians, an approach that ensures the same input-output behaviour of the reduced model with regard to the original one