On the development of all-cellulose capsules by vesicle-templated Layer-by-Layer assembly

Polymeric multilayer capsules formed by the Layer-by-Layer (LbL) technique are interesting candidates for the purposes of storage, encapsulation, and release of drugs and biomolecules for pharmaceutical and biomedical applications. In the current study, cellulose-based core-shell particles were developed via the LbL technique alternating two cellulose derivatives, anionic carboxymethylcellulose (CMC), and cationic quaternized hydroxyethylcellulose ethoxylate (QHECE), onto a cationic vesicular template made of didodecyldimethylammonium bromide (DDAB). The obtained capsules were characterized by dynamic light scattering (DLS), ζ potential measurements, and high-resolution scanning electron microscopy (HR-SEM). DLS measurements reveal that the size of the particles can be tuned from a hundred nanometers with a low polydispersity index (deposition of 2 layers) up to micrometer scale (deposition of 6 layers). Upon the deposition of each cellulose derivative, the particle charge is reversed, and pH is observed to considerably affect the process thus demonstrating the electrostatic driving force for LbL deposition. The HR-SEM characterization suggests that the shape of the core-shell particles formed is reminiscent of the spherical vesicle template. The development of biobased nano- and micro-containers by the alternating deposition of oppositely charged cellulose derivatives onto a vesicle template offers several advantages, such as simplicity, reproducibility, biocompatibility, low-cost, mild reaction conditions, and high controllability over particle size and composition of the shell.Portuguese Foundation for Science and Technology, FCT, via the projects PTDC/ASP-SIL/30619/2017, UIDB/05183/2020 and the researcher grant CEECIND/01014/2018info:eu-repo/semantics/publishedVersio

Perspectives on the Lindman Hypothesis and cellulose interactions

In the history of cellulose chemistry, hydrogen bonding has been the predominant explanation when discussing intermolecular interactions between cellulose polymers. This is the general consensus in scholarly textbooks and in many research articles, and it applies to several other biomacromolecules’ interactions as well. This rather unbalanced description of cellulose has likely impacted the development of materials based on the processing of cellulose—for example, via dissolution in various solvent systems and regeneration into solid materials, such as films and fibers, and even traditional wood fiber handling and papermaking. In this review, we take as a starting point the questioning of the general description of the nature of cellulose and cellulose interactions initiated by Professor Björn Lindman, based on generic physicochemical reasoning about surfactants and polymers. This dispute, which became known as “the Lindman hypothesis”, highlights the importance of hydrophobic interactions in cellulose systems and that cellulose is an amphiphilic polymer. This paper elaborates on Björn Lindman’s contribution to the subject, which has caused the scientific community to revisit cellulose and reconsider certain phenomena from other perspectives.info:eu-repo/semantics/publishedVersio

Water Use Efficiency Variation and Its Components in Wheat Cultivars

Genetic variations of water use efficiency (WUE) in wheat cultivar were studied in different models. These models in addition accumulating WUE; evaluate the contribution of its components. In this study, seven bread wheat cultivars were sown at four separate randomized complete block design with four replications at different moisture regimes in two growing seasons. Combined analysis of variance showed significant differences for total dry matter, WUE, relative water loss (transpiration efficiency), and initial water of flag leaves (uptake efficiency). Sardary, Sabalan and Alamut cultivars had the lowest WUE and total dry matter, but Zarrin and Shahriar were the highest values. Sardary with low uptake efficiency and Zarrin with high grain yield had the minimum and maximum transpiration efficiency. The WUE and evapotranspiration efficiency had a positive significant correlation with total dry matter and grain yield respectively. Results of path analysis showed that WUE (0.6) and total dry matter (0.31) had the highest direct effect on grain yield. Contribution of evapotranspiration efficiency (0.82) on WUE was higher than harvest index (0.30)

Performance and some physiological traits of Iranian corn (Zea mays L.) varieties as impelled by drought stress

Plants are exposed to various environmental stresses. One of these factors is the amount of accessible water, which restricts the crop production. To study the effect of water deficit on physiological traits of five corn varieties (SC108, SC500, SC647, SC700 and SC704) at both vegetative and reproductive stages, two separate field experiments were carried out based on a randomized complete blocks design with five replications. Furthermore, by using poly ethylene glycol (PEG) 6000, the influence of dehydration on both normal and stressed seeds of field experiment was assessed in glasshouse. Results revealed that grain yield (-48%), relative water content (-26%), leaf chlorophyll (-32%) decreased and electrical conductivity (+98%), potassium (+104%), carbohydrates (+47%) contents increased under drought. Maximum and minimum grain yield were obtained in SC704 and SC108, respectively. In glasshouse experiments, radicle and plumule length and dry weight declined when comparing to non-stress conditions. SC704 and SC500 were identified as the most tolerant varieties at both field and glasshouse experiments, respectively. None of the stressed seeds of the field experiment germinated using PEG 6000.Las plantas están expuestas a varios estreses ambientales. Uno de estos factores es la cantidad de agua accesible, lo que limita la producción de cultivos. Para estudiar el efecto del déficit hídrico sobre los caracteres fisiológicos de cinco variedades de maíz (SC108, SC500, SC647, SC700 y SC704) en las etapas vegetativas y reproductivas, se realizaron dos experimentos de campo independientes en un diseño de bloques completos al azar con cinco repeticiones. Además, mediante el uso de poly ethylene glycol (PEG) 6000, se evaluó en el invernadero, la influencia de la deshidratación de semillas normales y bajo estrés provenientes del experimento de campo. Los resultados revelaron que el rendimiento de granos (-48%), contenido relativo de agua (-26%) y la clorofila en las hojas (-32%) disminuyeron y la conductividad eléctrica (+98%), potasio (+104%) y contenido de carbohidratos (+47%) aumentaron bajo la sequedad. El rendimiento máximo y mínimo del grano fue obtenido para las variedades SC704 y SC108, respectivamente. En los experimentos de invernadero, la longitud y peso seco de las raíces y de la plúmula se redujeron en comparación con la condición sin estrés. SC704 y SC500 se identificaron como las variedades más tolerantes en experimentos de campo y de invernadero, respectivamente. Ninguna de las semillas bajo estrés del experimento de campo germinó utilizando PEG 6000

EVALUATION THE EFFECT OF PLANTING DATE ON COLD TOLERANCE IN BARLEY GENOTYPES

ABSTRACT In order to evaluate cold tolerance of twenty barley genotypes under field conditions an experiment was carried out with Randomized Complete Blocks Design at 3 sowing dates (October 6, November 5 and December 5) during 2011 -2012 seasons. Also, another experiment was done on the same genotypes based on Completely Randomized Design with 5 replications under greenhouse conditions. Results analysis of variance showed that significant differences between sowing dates for traits of plant height, spike per m 2 , grain per spike, 1000 KW and grain yield. First sowing date at October had higher spike per m 2 , 1000 KW, grain yield and total dry matter. There were significant differences, for total dry matter and ion leakage at 4 and 6 leaves stage. The highest and lowest ion leakages were observed at Redut/OK84817 (37.30µds/m 2 ) and Legia/CWB117-5-9-5 (21.44µds/m 2 ) genotypes, respectively. Traits of 1000 KW, total dry matter had positive significant correlations with grain yield r = 0.62 ** and r =0.74 ** , respectively. It seems that these traits could be used an indirect criteria for cold tolerance evaluation. At regression analysis with stepwise method 1000-kernel weight and harvest index remained at final model. Cluster analysis with all traits showed that genotypes of 12, 16, 4, 3, 17, 8, 15, 7, 14, 20, 11 and 9 were superior genotypes. At principal component analysis four first components showed 80.9% from total variation. First component was important at improving grain yield and third components named as a grain yield components

On Structural and Molecular Order in Cellulose Acetate Butyrate Films

Cellulose acetate butyrate (CAB) is a possible candidate, being a raw material derived from renewable resources, to replace fossil-based materials. This is due to its thermoplastic properties and the relative ease with which it could be implemented within the existing industry. With a significant amount of variation in CAB on the market today, a knowledge gap has been identified regarding the understanding of the polymer structural arrangement in films. This relates to the underlying mechanisms that regulate CAB film material properties, insights that are important in product development. In this study, commercially available CAB was investigated with XRD, SEM, AFM, and TOPEM DSC in order to obtain physicochemical information related to its micro-structural features in solvent-cast films. The film-forming ability relates mostly to the number of hydroxyl groups, and the semi-crystallinity of the films depends on the type and position of the side groups along the cellulose backbone. The appearance of signs of possible cholesteric ordering in the films could be connected to higher amounts of hydroxyl groups along the backbone that disturb the helix arrangement, while the overall order was primarily related to the butyrate substitution and secondarily related to the molecular weight of the particular CAB studied. Cold crystallization was also observed in one CAB sample