Improving Electrical Properties of Polypropylene/GNP composites Using Compatibilizer and Solvent-Assisted Melt Blending

Over the past few years, polymer products have become essential to our lives. Many people may think that polymers are simply plastics, however, that is just the tip of the iceberg. Polymer products are used in food, sport, medical, and technological industries. There have been numerous applications in all these areas, but in the technological industry, electronic devices, in particular, are affected by electrostatic discharge (ESD) generated by friction during handling, packaging, or transportation. This requires the use of antistatic packaging, a special package that has low electrical resistivity in order to avoid electron accumulation. This study is an attempt to address this knowledge gap by use of compatibilizer approach & filler system to deliver high value improvements to microinjection molded parts

Influence of Zn excess on compositional, structural and vibrational properties of Cu2ZnSn0.5Ge0.5Se4 thin films and their effect on solar cell efficiency

This Accepted Manuscript will be available for reuse under a CC BY-NC-ND licence after 24 months of embargo periodThe effect of Zn content on compositional, structural and vibrational properties of Cu2ZnSn1-xGexSe4 (CZTGSe, x ~ 0.5) thin films is studied. Kesterite layer is deposited by co-evaporation onto 5 × 5 cm2 Mo/SLG substrate followed by a thermal treatment at maximum temperature of 480 °C, obtaining areas with different composition and morphology which are due to the sample position in the co-evaporation system and to the non-uniform temperature distribution across the substrate. Kesterite layers with higher Zn amounts are characterized by lower Cu and Ge contents; however, a uniform Ge distribution through the absorber layer is detected in all cases. The excess Zn concentration leads to the formation of ZnSe secondary phase on the surface and in the bulk of the absorber as determined by Raman spectroscopy. When higher Ge content and no ZnSe are present in the absorber layer, a compact structure is formed with larger grain size of kesterite. This effect could explain the higher Voc of the solar cell. The Zn content does not affect the bandgap energy significantly (Eg near 1.3 eV), although the observed effect of Zn excess in CZTGSe results in a decreased device performance from 6.4 to 4.2%. This investigation reveals the importance of the control of the off-stoichiometric CZTGSe composition during the deposition process to enhance solar cells propertiesThis work was supported by Spanish Ministry of Science, Innovation and Universities Project WINCOST (ENE2016-80788-C5-2-R) and European Project INFINITE CELL (H2020-MSCA-RISE-2017-777968). ARP also acknowledges financial support from Community of Madrid within Youth Employment Program (PEJD-2017-PRE/IND-4062). MG acknowledges the financial support from ACCIÓ-Generalitat de Catalunya within the TECNIOspring Plus fellowship (TECSPR18-1-0048

Steps to Reconstitute in vitro a Complete Round of COPI vesicle Budding, Uncoating and Fusion

Among the three functionally characterized vesicles within the cell (Clathrin, COPII and COPI coated vesicles), COPI vesicles mediate the transport in both anterograde and retrograde transport within the Golgi complex (Orci et al., 1997) as well as recycling of proteins from the Golgi to the ER (Cosson and Letourneur, 1994; Letourneur et al., 1994). An in vitro based assay using soluble coatomer and ARF1 together with synthetic liposomes containing p23 tail peptide yielded generation of COPI vesicles, thus establishing the minimal requirements for COPI coat assembly (Bremser et al., 1999). In a program to reconstitute one round of budding, uncoating and fusion of a COPI vesicle from defined components, the next step is to include in a liposomal system the components needed for the fusion reaction. For that purpose, SNAREs (Soluble N-Ethylmaleimid-sensitive fusion protein Attachment protein REceptors) were required since they were shown to be the machinery for fusion (McNew et al., 2000; Nickel et al., 1999; Sollner et al., 1993; Weber et al., 1998)). To study their behavior in the COPI budding process, different ER and Golgi SNAREs (Sec22p, Vti1p, Gos1p, Bos1p, Bet1p, Ykt6p) were produced in bacteria, purified and reconstituted into liposomes in their correct physiological orientation. Sec22p and Vti1p do not seem to be preferentially taken up in COPI coated vesicles under the conditions of the in vitro budding assay. Preliminary data allowed reconstitution of SNARE complexes and further experiments should allow the study of the mechanisms involved in their specific uptake in COPI vesicles. Prior to fusion, vesicles need to be uncoated. This process was shown to be dependent on ARF1-GTP hydrolysis (Tanigawa et al., 1993), a reaction catalyzed by ARF-GTPase activating protein (ARF-GAP). Therefore myristoylated yeast ARF1p as well as its ARF-GAP (Glo3p) was produced in bacteria, purified to apparent homogeneity and in an active state with regard to exchange of nucleotide and GTP hydrolysis in presence of liposomes. Moreover, selecting for large size liposomes used in the in vitro budding assay was critical to ensure newly formed vesicles are authentic ones and not preexisting small structures. Therefore, gel filtration experiments were successfully used to achieve this goal. Tools were provided to reconstitute one round of vesicular transport in vitro. Active proteins (ARF1p, coatomer) involved in coat assembly, ARF-GAP required for uncoating and the fusion machinery proteins SNAREs were provided. A Homogenous population of large liposomes was generated so that the total signal observed after budding is due only to de novo generated COPI vesicles and not to preexisting small structures

Etude des signalisations autophagique et neurotrophique dans des lignées de glioblastome humain activées lors de l’hypoxie

Glioblastoma multiform (GBM), a primary brain tumor that is the most common and the most aggressive. It’s characterized by a high degree of hypoxia and a resistance to therapy because of its adaptation capacities including autophagy. This degradation process allows recycling of cellular components to produce precursors for anabolism and ATP. We have studied the hypoxia-induced autophagy in three human GBM cell lines, the U87MG, M059K and M059J. We have found a survival hypoxia-induced autophagy that was efficient in all cell lines. Indeed, we observed an accumulation of autophagosomes when we inhibited the autophagic flux with chloroquine (CQ). Treatment with CQ or interference of Beclin1 or Atg5 expression by specific siRNA in GBM cells significantly decreased their metabolic activity and growth. However, we did not detect PARP cleavage by western blotting. Thus, we verified the neurotrophic signaling as another survival pathway by which GBM cells resist to hypoxia. After hypoxia, the transcription level of TrkC FL (full length), TrkC-T1 (truncated TrkC) and the NT-3 (the TrkC ligand) significantly increases in the U87MG cell lines, as far as the translation level of TrkC FL and TrkC-T1. When we explored the TrkC FL signaling pathway, there was an increase in the phosphorylation level of p38. After inhibition of this MAPK, we observed PARP cleavage, which was particularly important in hypoxia conditions. This cleavage was further enhanced upon CQ treatment. The autophagy inhibition using either CQ, siBeclin1 or siAtg5, increases TrkC FL and T1 expression, suggesting that in the absence of autophagy, cells would adapt by increasing TrkC signaling.Finally, we have verified for hypoxic (BNIP3) and autophagic (LC3) markers on tumor sections from patients with GBM. We confirmed the hypoxic character of GBM, and showed important autophagy activation, after autophagosomes quantification. In comparison with cavernoma (benign brain tumor), patients with GBM showed a significant increase in TrkC and NT-3 expression, highlighting the importance of neurotrophic signaling in GBM tumor cell survival.Le glioblastome multiforme (GBM) est la tumeur cérébrale la plus fréquente et la plus agressive. Il s’agit d’une tumeur capable de survivre même dans des conditions d’oxygénation faible ou hypoxie. En effet, les cellules cancéreuses du GBM activent des voies de survie en réponse à cette privation de dioxygène, dont l’autophagie. Il s’agit d’un mécanisme catabolique conduisant à la dégradation des constituants cellulaires, générant ainsi des précurseurs pour l’anabolisme cellulaire ainsi que de l’ATP. Nous avons étudié l’activation de l’autophagie en réponse à l’hypoxie, dans trois lignées cellulaires de GBM humain, les U87MG, les M059K et les M059J. Une autophagie de survie est activée dans les trois lignées cellulaires, en réponse à l’hypoxie. L’inhibition du flux autophagique par la chloroquine (CQ), induit une accumulation des autophagosomes, soulignant ainsi l’efficacité du processus. L’inhibition de l’autophagie par la CQ ou par des siRNA spécifiques dirigés contre les transcrits de Beclin1 ou d’Atg5, entraîne une diminution significative de l’activité métabolique cellulaire, ainsi qu’un retard de prolifération. Toutefois, nous n’avons pas détecté de mort apoptotique dépendante des caspases. Nous avons donc étudié une deuxième voie de signalisation de survie cellulaire, la signalisation neurotrophique. Une augmentation significative des transcrits de TrkC FL et T1 (TrkC tronqué) ainsi que de leur ligand, la NT-3 a été observée dans les cellules U87MG cultivées en hypoxie. De même, le taux de production des protéines TrkC FL et T1 a significativement augmenté en hypoxie. L’augmentation de l’expression du TrkC FL était accompagnée par une augmentation de sa phosphorylation et de celle de la p38 MAPK. L’inhibition de cette dernière par siRNA induit un clivage de la PARP, qui est d’autant plus important suite à l’ajout de la CQ. Ces effets étaient plus marqués au niveau des cellules cultivées en hypoxie. L’inhibition de l’autophagie par la CQ, augmente l’expression de TrkC FL et la phosphorylation de la p38, ce qui suggère qu’en absence de l’autophagie, les cellules s’adapteraient en augmentant la signalisation du TrkC.La recherche des zones hypoxiques et autophagiques sur des coupes de tumeurs issues de patients atteints de GBM, confirme le caractère hypoxique de cette tumeur, et montre une induction du processus autophagique. En comparaison avec le cavernome (tumeur cérébrale bénigne), les patients atteints de GBM montrent une augmentation significative de l’expression de TrkC et de NT-3, ce qui renforce l’importance de la signalisation neurotrophique dans la survie des cellules de GBM

Collagen-containing scaffolds enhance attachment and proliferation of non-cultured bone marrow multipotential stromal cells

Large bone defects are ideally treated with autografts, which have many limitations. Therefore, osteoconductive scaffolds loaded with autologous bone marrow (BM) aspirate are increasingly used as alternatives. The purpose of this study was to compare the growth of multipotential stromal cells (MSCs) from unprocessed BM on a collagen-containing bovine bone scaffold (Orthoss® Collagen) with a non-collagen-containing bovine bone scaffold, Orthoss®. Another collagen-containing synthetic scaffold, Vitoss® was included in the comparison. Colonization of scaffolds by BM MSCs (n = 23 donors) was evaluated using microscopy, colony forming unit-fibroblast assay and flow-cytometry. The number of BM MSCs initially attached to Orthoss® Collagen and Vitoss® was similar but greater than Orthoss® (p = 0.001 and p = 0.041, respectively). Furthermore, the number of MSCs released from Orthoss® Collagen and Vitoss® after 2-week culture was also higher compared to Orthoss® (p = 0.010 and p = 0.023, respectively). Interestingly, collagen-containing scaffolds accommodated larger numbers of lymphocytic and myelomonocytic cells. Additionally, the proliferation of culture-expanded MSCs on Orthoss® collagen and Vitoss® was greater compared to Orthoss® (p = 0.047 and p = 0.004, respectively). Collectively, collagen-containing scaffolds were superior in supporting the attachment and proliferation of MSCs when they were loaded with unprocessed BM aspirates. This highlights the benefit of collagen incorporation into bone scaffolds for use with autologous bone marrow aspirates as autograft substitutes

PHYTOCHEMICAL CHARACTERIZATION AND ANTIOXIDANT ACTIVITY OF THE NORTHERN MOROCCAN SPECIES: WITHANIA FRUTESCENS L.

Objective: In this study, we were interested in qualitative, quantitative phytochemical characterization and evaluation of the antioxidant capacity of the total extracts of a plant from northern Morocco, the species selected for this study is Withania frutescens. Materials and Methods: Analysis of mineral elements by inductive coupling plasma-atomic absorption spectroscopy (ICP-AES), phytochemical screening, polyphenol and tannin assays, evaluation of antioxidant activity by the 1,2-diphenyl-β-picrylhydrazyl (DPPH) free radical scavenging method and reducing power. Results: The plant contains alkaloids, saponins, tannins, mucilages, and coumarins. It has a relatively high content of total polyphenols and tannins of 19.53±0.018 μg genetic generalized epilepsy/mg MS and 6.258±0.062 μg Eqcat/mg MS, respectively. The analysis of mineral elements by ICP-AES shows that our species is rich in mineral elements which are calcium, magnesium, and sodium, and it is devoid of metallic elements such as nickel, lead, cadmium, and cobalt. The evaluation of antioxidant activity by the DPPH free radical scavenging method shows that the half maximal inhibitory concentration of the tested extracts has an antiradical activity of about 0.056±0.008 μg/ml for the ethanol extract and 0.213±0.004 μg/ml for the methanol extract compared to the butylated hydroxytoluene value of 0.009±0.0004 μg/ml which was used as a reference. The reducing capacity test shows that methanolic extract has a high antioxidant capacity (0.213±0.006) compared to ethanolic extract (0.043±0.004) but remains low compared to ascorbic acid (0.003±0.0004) which was used as reference. Conclusion: Phytochemical analysis of W. frutescens shows that this plant is rich in high quantities of alkaloids, saponins, mucilage, tannins, and coumarins. It contains an average amount of total polyphenols and tannins that confer significant antioxidant activity to the plant studied

Film as a Generative Catalyst for an Empathic University Curriculum

Film screening may enhance the Moroccan university curriculum by providing supplementary educational tools. While the regular educational vision suggests intentional and direct methods, film screening opens promising prospects arising from indirect and deeper emotional perspective. The class composition, in general, imposes certain pedagogical association between professor and students since what matters within the conventional context is the communicative perspective involving the cognitive criteria. What concerns the empathic dimension contrastingly is how to shape a dynamic interaction between emotional and cognitive moods. However, though there is an apparent sort of assimilation and reciprocity between the normative educational class and the empathic one on the ground that the filmmaker takes the place of the university professor while students act as spectators, the question is still open on whether there is any qualitative addition behind film screening that would make a difference

Functional expression of Multidrug Resistance Protein 4 MRP4/ABCC4

To study the function and structure of membrane proteins, high quantities of pure and stable protein are needed. One of the first hurdles in accomplishing this is expression of the membrane protein at high levels and in a functional state. Membrane proteins are naturally expressed at low levels, so finding a suitable host for overexpression is imperative. Multidrug resistance protein 4 (MRP4) or ATP-binding cassette subfamily C member 4 (ABCC4) is a multi-transmembrane protein that is able to transport a range of organic anionic compounds (both endogenous and xenobiotic) out of the cell. This versatile transporter has been linked with extracellular signaling pathways and cellular protection, along with conferring drug resistance in cancers. Here we report the use of MRP4 as a case study to be expressed in three different expression systems: mammalian, insect, and yeast cells, to gain the highest yield possible. Interestingly, using the baculovirus expression system with Sf9 insect cells produced the highest protein yields. Vesicular transport assays were used to confirm that MRP4 expressed in Sf9 was functional using a fluorescent cAMP analogue (fluo-cAMP) instead of the traditional radiolabeled substrates. MRP4 transported fluo-cAMP in an ATP-dependent manner. The specificity of functional expression of MRP4 was validated by the use of nonhydrolyzable ATP analogues and MRP4 inhibitor MK571. Functionally expressed MRP4 in Sf9 cells can now be used in downstream processes such as solubilization and purification in order to better understand its function and structure

Stabilization of human Multidrug Resistance Protein 4 (MRP4/ABCC4) using novel solubilization agents.

Membrane proteins (MPs) are important drug discovery targets for a wide range of diseases. However, elucidating the structure and function of native MP is notoriously challenging as their original structure has to be maintained once removed from the lipid bilayer. Conventionally, detergents have been used to solubilize MP with varying degrees of success concerning MP stability. To try to address this, new, more stabilizing agents have been developed, such as calixarene-based detergents and styrene–maleic acid (SMA) copolymer. Calixarene-based detergents exhibit enhanced solubilizing and stabilizing properties compared with conventional detergents, whereas SMA is able to extract MPs with their surrounding lipids, forming a nanodisc structure. Here we report a comparative study using classical detergents, calixarene-based detergents, and SMA to assess the solubilization and stabilization of the human ABC transporter MRP4 (multidrug resistance protein 4/ABCC4). We show that both SMA and calixarene-based detergents have a higher solubility efficiency (at least 80%) than conventional detergents, and show striking overstabilization features of MRP4 (up to 70 °C) with at least 30 °C stability improvement in comparison with the best conventional detergents. These solubilizing agents were successfully used to purify aggregate-free, homogenous and stable MRP4, with sevenfold higher yield for C4C7 calixarene detergent in comparison with SMA. This work paves the way to MRP4 structural and functional investigations and illustrates once more the high value of using calixarene-based detergent or SMA as versatile and efficient tools to study MP, and eventually enable drug discovery of challenging and highly druggable targets