An overview of temperature issues in microwave-assisted pyrolysis

Microwave-assisted pyrolysis is a promising thermochemical technique to convert waste polymers and biomass into raw chemicals and fuels. However, this process involves several issues related to the interactions between materials and microwaves. Consequently, the control of temperature during microwave-assisted pyrolysis is a hard task both for measurement and uniformity during the overall pyrolytic run. In this review, we introduce some of the main theoretical aspects of the microwaves–materials interactions alongside the issues related to microwave pyrolytic processability of materials

Environmental-dependent proline accumulation in plants living on gypsum soils

[EN] Biosynthesis of proline¿or other compatible solutes¿is a conserved response of all organisms to different abiotic stress conditions leading to cellular dehydration. However, the biological relevance of this reaction for plant stress tolerance mechanisms remains largely unknown, since there are very few available data on proline levels in stress-tolerant plants under natural conditions. The aim of this work was to establish the relationship between proline levels and different environmental stress factors in plants living on gypsum soils. During the 2-year study (2009¿2010), soil parameters and climatic data were monitored, and proline contents were determined, in six successive samplings, in ten taxa present in selected experimental plots, three in a gypsum area and one in a semiarid zone, both located in the province of Valencia, in south-east Spain. Mean proline values varied significantly between species; however, seasonal variations within species were in many cases even wider, with the most extreme differences registered in Helianthemum syriacum (almost 30 lmol g-1 of DW in summer 2009, as compared to ca. 0.5 in spring, in one of the plots of the gypsum zone). Higher proline contents in plants were generally observed under lower soil humidity conditions, especially in the 2009 summer sampling preceded by a severe drought period. Our results clearly show a positive correlation between the degree of environmental stress and the proline level in most of the taxa included in this study, supporting a functional role of proline in stress tolerance mechanisms of plants adapted to gypsum. However, the main trigger of proline biosynthesis in this type of habitat, as in arid or semiarid zones, is water deficit, while the component of ¿salt stress¿ due to the presence of gypsum in the soil only plays a secondary role.This work has been supported by the Spanish Ministry of Science and Innovation (Project CGL2008-00438/BOS), with contribution from the European Regional Development Fund.Boscaiu, M.; Bautista Carrascosa, I.; Lidón Cerezuela, AL.; Llinares Palacios, JV.; Lull, C.; Donat-Torres, M.; Mayoral García-Berlanga, O.... (2013). Environmental-dependent proline accumulation in plants living on gypsum soils. Acta Physiologiae Plantarum. 35:2193-2204. https://doi.org/10.1007/s11738-013-1256-3S2193220435Alvarado JJ, Ruiz JM, López-Cantarero I, Molero J, Romero L (2000) Nitrogen metabolism in five plant species characteristic of gypsiferous soils. J Plant Physiol 156:612–616Ashraf M, Foolad MR (2007) Roles of glycine betaine and proline in improving plant abiotic stress resistance. Environ Exp Bot 59:206–216Bates LS, Waldren RP, Teare ID (1973) Rapid determination of free proline for water stress studies. Plant Soil 39:205–207Briens M, Larher F (1982) Osmoregulation in halophytic higher plants: a comparative study of soluble carbohydrates, polyols, betaines and free proline. Plant, Cell Environ 5:287–292Burriel F, Hernando V (1947) Nuevo método para determinar el fósforo asimilable en los suelos. Anales de Edafología y Fisiología Vegetal 9:611–622Caballero I, Olano JM, Loidi J, Escudero A (2003) Seed bank structure along a semi-arid gypsum gradient in Central Spain. J Arid Environ 55:287–299Escudero A, Carnes LF, Pérez García F (1997) Seed germination of gypsophytes and gypsovags in semi-arid central Spain. J Arid Environ 36:487–497Escudero A, Somolinos RC, Olano JM, Rubio A (1999) Factors controlling the establishment of Helianthemum squamatum, an endemic gypsophite of semi-arid Spain. J Ecol 87:290–302FAO (1990) Management of gypsiferous soils. FAO Soils Bull 62Ferriol M, Pérez I, Merle H, Boira H (2006) Ecological germination requirements of the aggregate species Teucrium pumilum (Labiatae) endemic to Spain. Plant Soil 284:205–216Flowers TJ, Colmer TD (2008) Salinity tolerance in halophytes. New Phytol 179:945–963Flowers TJ, Troke PF, Yeo AR (1977) The mechanism of salt tolerance in halophytes. Ann Rev Plant Physiol 28:89–121Gil R, Lull C, Boscaiu M, Bautista I, Lidón A, Vicente O (2011) Soluble carbohydrates as osmolytes in several halophytes from a Mediterranean salt marsh. Not Bot Horti Agrobo 39(2):9–17Grigore MN, Boscaiu M, Vicente O (2011) Assessment of the relevance of osmolyte biosynthesis for salt tolerance of halophytes under natural conditions. Eur J Plant Sci Biotech 5:12–19Hare PD, Cress WA, Van Standen J (1998) Dissecting the roles of osmolyte accumulation during stress. Plant Cell Environ 21:535–553Keeney DR, Nelson DW (1982) Nitrogen inorganic forms. In: Page AL et al (eds) Methods of soil analysis, part 2: chemical and microbiological properties. Soil Science Society of America, Madison, pp 643–698Knudsen D, Peterson GA, Pratt PF (1982) Lithium, Sodium and Potassium. In: Page AL et al (eds) Methods of soil analysis, part 2: chemical and microbiological properties. Soil Science Society of America, Madison, pp 225–246Kuo S (1996) Phosphorus. In: Spark DL (ed) Methods of soil analysis: chemical methods, part 3. Soil Science Society of America, Madison, pp 869–919Martens H, Maes T (1989) Multivariate calibration. Wiley, New York, pp 97–108Martínez-Duro E, Ferrandis P, Escudero A, Luzuriaga AL, Herranz JM (2010) Secondary old-field succession in an ecosystem with restrictive soils: does time from abandonment matter? Appl Veg Sci 13:234–248Meyer SE (1986) The ecology of gypsophile endemism in the eastern Mojave desert. Ecology 67:1303–1313Meyer SE, García-Moya E (1989) Plant community patterns and soil moisture regime in gypsum grasslands of north central Mexico. J Arid Environ 16:147–155Meyer SE, García-Moya E, Lagunes-Espinoza LC (1992) Topographic and soil surface effects on gypsophile plant community patterns in central Mexico. J Veg Sci 3:429–438Moruno F, Soriano P, Vicente O, Boscaiu M, Estrelles E (2011) Opportunistic germination behaviour of Gypsophila (Caryophyllaceae) in two priority habitats from semi-arid Mediterranean steppes. Not Bot Horti Agrobo 39(1):18–23Mota JF, Sánchez Gómez P, Merlo Calvente ME, Catalán Rodríguez P, Laguna Lumbreras E, de la Cruz Rot M, Navarro Reyes FB, Marchal Gallardo F, Bartolomé Esteban C, Martínez Labarga JM, Sainz Ollero H, Valle Tendero F, Serra Laliga L, Martínez Hernández F, Garrido Becerra JA, Pérez García FJ (2009) Aproximación a la checklist de los gipsófitos ibéricos. Anales de Biología 31:71–80Murakeözy ÉP, Nagy Z, Duhazé C, Bouchereau A, Tuba Z (2003) Seasonal changes in the levels of compatible osmolytes in three halophytic species of inland saline vegetation in Hungary. J Plant Physiol 160:395–401Nelson DW, Sommers LE (1982) Total carbon, organic carbon, and organic matter. In: Page AL et al (eds) Methods of soil analysis, part 2: chemical and microbiological properties. Soil Science Society of America, Madison, pp 539–577Palacio S, Escudero A, Montserrat-Martí G, Maestro M, Milla R, Albert M (2007) Plants living on gypsum: beyond the specialist model. Ann Bot 99:333–343Parsons RF (1977) Gypsophily in plants—a review. Am Midl Nat 96:1–20Pueyo Y, Alados CL, Maestro M, Komac B (2007) Gypsophile vegetation patterns under a range of soil properties induced by topographical position. Plant Ecol 189:301–311Rivas-Martínez S, Rivas-Sáenz S (2009) Worldwide Bioclimatic Classification System. Phytosociological Research Center, Complutense University of Madrid, Spain. http://www.globalbioclimatics.org/ . Accessed 15 Nov 2012Romão RL, Escudero A (2005) Gypsum physical soil crusts and the existence of gypsophytes in semi-arid central Spain. Plant Ecol 181:127–137Rubio A, Escudero A (2000) Small-scale spatial soil-plant relationship in semi-arid gypsum environment. Plant Soil 220:139–150Ruíz JM, López-Cantarero I, Rivero RM, Romero L (2003) Sulphur phytoaccumulation in plant species characteristic of gypsiferous soils. Int J Phytorem 5:203–210Szabados L, Savouré A (2010) Proline: a multifunctional amino acid. Trends Plant Sci 15:89–97Szabados L, Kovács H, Zilberstein A, Bouchereau A (2011) Plants in extreme environments: importance of protective compounds in stress tolerance. Adv Bot Res 57:105–150Tecator Application Note (1984) AN 5226: Determination of ammonium in 2 M KCl soil extracts by FIAstar 5000. AN 5201: Determination of the sum of nitrate and nitrite in water by FIAstar 5000. (Adapted for 2 M KCl soil extracts)Tipirdamaz R, Gagneul D, Duhazé C, Aïnouche A, Monnier C, Özkum D, Larher F (2006) Clustering of halophytes from an inland salt marsh in Turkey according to their ability to accumulate sodium and nitrogenous osmolytes. Environ Exp Bot 57:139–153Verheye WH, Boyadgiev TG (1997) Evaluating the land use potential of gypsiferous soils from field pedogenic characteristics. Soil Use Manage 13:97–103Vicente O, Boscaiu M, Naranjo MA, Estrelles E, Bellés JM, Soriano P (2004) Responses to salt stress in the halophyte Plantago crassifolia (Plantaginaceae). J Arid Environ 58:463–481Yancey PH (2005) Organic osmolytes as compatible, metabolic and counteracting cytoprotectants in high osmolarity and other stresses. J Exp Biol 208:2819–283

Powder Compaction: Compression Properties of Cellulose Ethers

Effective development of matrix tablets requires a comprehensive understanding of different raw material attributes and their impact on process parameters. Cellulose ethers (CE) are the most commonly used pharmaceutical excipients in the fabrication of hydrophilic matrices. The innate good compression and binding properties of CE enable matrices to be prepared using economical direct compression (DC) techniques. However, DC is sensitive to raw material attributes, thus, impacting the compaction process. This article critically reviews prior knowledge on the mechanism of powder compaction and the compression properties of cellulose ethers, giving timely insight into new developments in this field

Autothermal reforming of palm empty fruit bunch bio-oil: thermodynamic modelling

This work focuses on thermodynamic analysis of the autothermal reforming of palm empty fruit bunch (PEFB) bio-oil for the production of hydrogen and syngas. PEFB bio-oil composition was simulated using bio-oil surrogates generated from a mixture of acetic acid, phenol, levoglucosan, palmitic acid and furfural. A sensitivity analysis revealed that the hydrogen and syngas yields were not sensitive to actual bio-oil composition, but were determined by a good match of molar elemental composition between real bio-oil and surrogate mixture. The maximum hydrogen yield obtained under constant reaction enthalpy and pressure was about 12 wt% at S/C = 1 and increased to about 18 wt% at S/C = 4; both yields occurring at equivalence ratio Φ of 0.31. The possibility of generating syngas with varying H2 and CO content using autothermal reforming was analysed and application of this process to fuel cells and Fischer-Tropsch synthesis is discussed. Using a novel simple modelling methodology, reaction mechanisms were proposed which were able to account for equilibrium product distribution. It was evident that different combinations of reactions could be used to obtain the same equilibrium product concentrations. One proposed reaction mechanism, referred to as the ‘partial oxidation based mechanism’ involved the partial oxidation reaction of the bio-oil to produce hydrogen, with the extent of steam reforming and water gas shift reactions varying depending on the amount of oxygen used. Another proposed mechanism, referred to as the ‘complete oxidation based mechanism’ was represented by thermal decomposition of about 30% of bio-oil and hydrogen production obtained by decomposition, steam reforming, water gas shift and carbon gasification reactions. The importance of these mechanisms in assisting in the eventual choice of catalyst to be used in a real ATR of PEFB bio-oil process was discussed

"L’implacable lumière du Nord" : l’impressionnisme littéraire chez les auteurs scandinaves et britanniques à la fin du XIXe siècle

L’impressionnisme littéraire, bien que traité dans nombre de travaux, demeure un concept vague, aux définitions multiples, et dont l’existence même est contestée par certains critiques. Afin de dépasser ces querelles, cette étude propose de l’analyser comme un moteur décisif du développement du modernisme dans le nord de l’Europe (Grande-Bretagne et Scandinavie) à la fin du XIXe siècle. Le corpus porte principalement sur des auteurs tels Henry James, Herman Bang, Stella Kleve et Thomas Hardy qui ont eux-mêmes fait des rapprochements entre impressionnisme et esthétique littéraire. A partir d’un repérage de caractéristiques stylistiques essentielles, fondée notamment sur des analyses texte-image, la thèse montre l’importance de l’impressionnisme littéraire dans l’émergence d’une nouvelle esthétique fondée sur la subjectivité et ouvrant la voie au « tournant vers l’intérieur » (le « inward turn » analysé par Erich Kahler). Elle établit un parallèle entre deux histoires littéraires : celle d’un terme ayant permis une théorisation autoréflexive du modernisme naissant, et celle de l’impression littéraire dans la fiction du nord de l’Europe, qui précède le mouvement artistique qui lui donnera son nom. Enfin, la mise en perspective des préoccupations esthétiques et des différentes formes d’engagement des auteurs aboutit à défendre l’hypothèse que l’empathie esthétique est un principe structurant du moment impressionniste, tant dans ses dimensions littéraires et artistiques que sociales.2018MULH889