In Situ Compatibilization of Biopolymer Ternary Blends by Reactive Extrusion with Low-Functionality Epoxy-Based Styrene Acrylic Oligomer

[EN] The present study reports on the use of low-functionality epoxy-based styrene¿acrylic oligomer (ESAO) to compatibilize immiscible ternary blends made of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), polylactide (PLA), and poly(butylene adipate-co-terephthalate) (PBAT). The addition during melt processing of low-functionality ESAO at two parts per hundred resin (phr) of biopolymer successfully changed the soften inclusion phase in the blend system to a thinner morphology, yielding biopolymer ternary blends with higher mechanical ductility and also improved oxygen barrier performance. The compatibilization achieved was ascribed to the in situ formation of a newly block terpolymer, i.e. PHBVb- PLA-b-PBAT, which was produced at the blend interface by the reaction of the multiple epoxy groups present in ESAO with the functional terminal groups of the biopolymers. This chemical reaction was mainly linear due to the inherently low functionality of ESAO and the more favorable reactivity of the epoxy groups with the carboxyl groups of the biopolymers, which avoided the formation of highly branched and/or cross-linked structures and thus facilitated the films processability. Therefore, the reactive blending of biopolymers at different mixing ratios with low-functionality ESAO represents a straightforward methodology to prepare sustainable plastics at industrial scale with different physical properties that can be of interest in, for instance, food packaging applications.This research was funded by the EU H2020 project YPACK (Reference number 773872) and by the Spanish Ministry of Science, Innovation, and Universities (MICIU) with project numbers MAT2017-84909-C2-2-R and AGL2015-63855-C2-1-R. L. Quiles-Carrillo wants to thank the Spanish Ministry of Education, Culture, and Sports (MECD) for financial support through his FPU Grant Number FPU15/03812. Torres-Giner also acknowledges the MICIU for his Juan de la Cierva contract (IJCI-2016-29675).Quiles-Carrillo, L.; Montanes, N.; Lagaron, J.; Balart, R.; Torres-Giner, S. (2019). In Situ Compatibilization of Biopolymer Ternary Blends by Reactive Extrusion with Low-Functionality Epoxy-Based Styrene Acrylic Oligomer. 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Дослідження електричних та структурних властивостей наночастинок діоксиду марганцю

Кристалічний діоксид марганцю (MnO2) готували методом розчинення в мікрохвильовій печі з використанням гідроксиду натрію як агента. Електропровідність, електричний модуль та діелектричні властивості наночастинок MnO2 були проаналізовані методом імпедансної спектроскопії в діапазоні частот від 1 до 8 МГц та діапазоні температур від 273 до 423 К. Провідність MnO2 зростає зі збільшенням частоти. Було встановлено, що температурна залежність провідності наночастинок підкоряється діаграмі Арреніуса, енергія активації становить – 0,088 еВ. Максимальна провідність виявляється рівною 311,79 См/см при конкретній температурі 298 К. Відповідна не дебаєвська поведінка у матеріалах MnO2 аналізується за допомогою аналізу модулів та діелектричних спектрів. Модульний і діелектричний спектри підтвердили процес релаксації. Діелектрична константа та діелектричні втрати були виявлені діелектричним спектральним аналізом. Діелектрична константа була постійною в області високих частот і варіювалася в області низьких частот. Діелектрична константа виявилася рівною – 1211 при певній температурі 298 К в області дуже низьких частот. Діелектричні втрати також були постійними при високих частотах в будь-яких температурних умовах і змінювались в області низьких частот. Структуру наночастинок MnO2 проаналізували методом порошкової рентгенівської дифракції. Результати порошкової рентгенографії показали, що підготовлений зразок наночастинок був кристалічним з тетрагональною фазою. За формулою Шеррера середній розмір кристалітів становить близько 20 нм.Crystalline manganese dioxide (MnO2) was prepared by microwave assisted solution method using sodium hydroxide as an agent. Electric conductivity, electric modulus and dielectric properties of MnO2 nanoparticles were analyzed by AC Impedance spectroscopy in the frequency range 1 to 8 MHz and temperature range in-between 273 K to 423 K. Conductivity of MnO2 increases with increasing frequency. Temperature dependence of the nanoparticle conductivity was found to obey the Arrhenius plot, activation energy is – 0.088 eV. The maximum conductivity is found to be 311.79 S/cm at a particular temperature of 298 K. The conformed non-Debye type behavior in the MnO2 materials is analyzed through modulus analysis and dielectric spectra. The modulus and dielectric spectra confirmed the relaxation process. Dielectric constant and dielectric loss were found from the dielectric spectral analysis. The dielectric constant was constant at high frequency region and varied at low frequency region. The dielectric constant is found to be – 1211 at a particular temperature of 298 K in very low frequency region. The dielectric loss also was constant at high frequencies in all temperature conditions and varied at low frequency region. Structure of MnO2 nanoparticles has been analyzed by powder X-ray diffraction method. The powder XRD results revealed that the prepared nanoparticles sample was crystalline with a tetragonal phase. Average crystallite size is found to be around 20 nm using Scherrer formula

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Not AvailableCarbon dioxide concentration is likely to increase by 2 2.5 fold by the end of 21st century from its current level of 400 ppm due to anthropogenic activities mediated climate change. As yam is an important food and nutrition security crop, it is of paramount importance to assess the effect of climate change on the physiological processes especially photosynthetic efficiency to identify the climate-smart varieties to meet the future food demand. The aim of this experiment was to assess the net photosynthetic rate, stomatal conductance, intercellular CO2, transpiration and physiological water use efficiency of seven yam varieties subjected to 400 ppm (ambient), 600, 800 and 1000 ppm (elevated carbon dioxide concentration). All the parameters were found significant at P<0.001. The mean photosynthetic rate increased significantly increased at 400 1000 ppm and no down-regulation was observed. Similar trend was observed in case of intercellular CO2 and physiological water use efficiency (WUEinstantaneous and WUEintrinsic). However, stomatal conductance increased significantly up to 800 and decreased at 1000 ppm. Contrasting results were recorded with regard to transpiration, which steadily decreased at ascending carbon dioxide concentrations. Further, photosynthesis rate had a significant (P<0.001) positive linear correlation with the elevated carbon dioxide (R2 = 0.783) and intercellular CO2 concentration (R2=0.763). White yam and greater yam were found to be responsive to elevated carbon dioxide as photosynthetic rate at 1000 ppm increased up to »68% in comparison to 400 ppm.Not Availabl

Real-time iTRAQ-based proteome profiling revealed the central metabolism involved in nitrogen starvation induced lipid accumulation in microalgae

To understand the post-transcriptional molecular mechanisms attributing to oleaginousness in microalgae challenged with nitrogen starvation (N-starvation), the longitudinal proteome dynamics of Chlorella sp. FC2 IITG was investigated using multipronged quantitative proteomics and multiple reaction monitoring assays. Physiological data suggested a remarkably enhanced lipid accumulation with concomitant reduction in carbon flux towards carbohydrate, protein and chlorophyll biosynthesis. The proteomics-based investigations identified the down-regulation of enzymes involved in chlorophyll biosynthesis (porphobilinogen deaminase) and photosynthetic carbon fixation (sedoheptulose-1,7 bisphosphate and phosphoribulokinase). Profound up-regulation of hydroxyacyl-ACP dehydrogenase and enoyl-ACP reductase ascertained lipid accumulation. The carbon skeletons to be integrated into lipid precursors were regenerated by glycolysis, beta-oxidation and TCA cycle. The enhanced expression of glycolysis and pentose phosphate pathway enzymes indicates heightened energy needs of FC2 cells for the sustenance of N-starvation. FC2 cells strategically reserved nitrogen by incorporating it into the TCA-cycle intermediates to form amino acids; particularly the enzymes involved in the biosynthesis of glutamate, aspartate and arginine were up-regulated. Regulation of arginine, superoxide dismutase, thioredoxin-peroxiredoxin, lipocalin, serine-hydroxymethyltransferase, cysteine synthase, and octanoyltransferase play a critical role in maintaining cellular homeostasis during N-starvation. These findings may provide a rationale for genetic engineering of microalgae, which may enable synchronized biomass and lipid synthesis

Molecular typing and differentiation of Mycobacterium tuberculosis clinical isolates using Double Repetitive Element PCR and Duplex PCR

Background: To date, the advancements in polymerase chain reaction (PCR) assures accurate, fast identification and mycobacterial speciation in clinical settings, which promotes a better tuberculosis (TB) treatment regimen. Methods: In this study, a total of 78 clinically suspected cases of TB were processed for the detection of Mycobacterial infections by standard Ziehl Neelsen (ZN) staining, conventional Lowenstein–Jensen (LJ) and BACTEC MGIT-960™ liquid culture. Strain typing was performed by using Double Repetitive Element PCR (DRE-PCR) and Duplex PCR (DPCR) to differentiate Mycobacterium tuberculosis complex (MTB) from non-tuberculous mycobacteria (NTM), respectively. Results: Of 78 clinical isolates, 25 (32%) were drug-susceptible, and 53 (68%) were resistant to at least one drug. The BACTEC MGIT-960™ showed the highest (88.5%) positivity rate, compared with conventional LJ (82%) and ZN smear (61.5%). The mean time detection and drug susceptibility for MTB was 28 and 40 days in LJ culture, and 10 and 13 days in BACTEC MGIT-960™ culture. Using DPCR, Mycobacterium avium infection was identified in HIV-positive (2.56%) and MTB in HIV-negative patients (97.4%), and the DRE-PCR system divulged 15 unique genotype patterns, and an institutional-based epidemiology database was created. Conclusions: The combination of an in-house DRE–DPCR system could possibly identify and differentiate MTB from other mycobacterial species in a single reaction. In addition, restriction polymorphism analysis and DNA sequencing of NTM could assist in species identification directly from clinical isolates