DSC analysis of Nd-Fe-B ribbons prepared by melt-spinning method with diverse compositions and cooling rates

Nd9.4Pr0.6Fe77.5-xB6Co6Ga0.5TixCx(x= 0, 1.5, 3, 4.5, 6) Melt-spun ribbons have been prepared at 15, 20 and 25 m/s quenching wheel speeds and were examined by using differential scanning calorimetry (DSC). It is remarkable that peak intensity increases with increasing solidification rate or the higher the Ti and C content of the structure. In both cases, the increased amounts of amorphous phase indicate their strongest peaks in the diagram. Another point related to the crystallization temperature of the ribbons in the presence of Ti and C, which will be discussed in detail in this manuscript

Introduction of nano-laminate Ti3SiC2 and SiC phases into Cf-C composite by liquid silicon infiltration method

The material Cf-C-SiC-Ti3SiC2 is promising for high temperature application. Due to the laminated structure and special properties, the Ti3SiC2 is one of the best reinforcements for Cf-C-SiC composites. In this paper, Cf-C-SiC-Ti3SiC2 composites were fabricated by liquid silicon infiltration (LSI) method; the effect of the TiC amount on the various composites properties were studied. For samples with 0, 50 and 90 vol.% of TiC, the results show that bending strength are 168, 190, and 181 MPa; porosities are 3.2, 4.7, and 9%; the fracture toughness are 6.1, 8.9, and 7.8 MPa∙m1/2; interlaminar shear strength are 27, 36, and 30 MPa; the amount of the MAX phase are 0, 8.5, and 5.6 vol.%, respectively. These results show that amount of TiC is not the main effective parameter in synthesis of Ti3SiC2. The existence of carbon promotes the synthesis of Ti3SiC2 indicating that only sufficient carbon content can lead to the appearance of Ti3SiC2 in the LSI process

Estudi dels exosomes com a mecanisme de comunicació intercel·lular en patologies pancreàtiques

[cat] La pancreatitis aguda és un procés inflamatori del pàncrees desencadenat per una activació inapropiada dels enzims pancreàtics. En la seva variant més severa, la malaltia progressa acompanyada d’afectacions no només a nivell local sino també sistèmic, essent la síndrome de resposta inflamatòria sistèmica (SIRS) i el dany pulmonar que se’n deriva una de les afectacions més primerenques i la principal causa de mortalitat dels pacients. Diferents estudis han identificat l’increment en l’expressió i secreció de múltiples mediadors inflamatoris, generats tant a nivell local com sistèmic. No obstant, el mecanisme patogènic de la malaltia encara es desconeix, de manera que en les fases inicials de la malaltia no és possible predir si un pacient desenvoluparà una variant lleu o severa de pancreatitis. A llarg dels últims anys, però, el descobriment dels exosomes ha revolucionat el camp de la comunicació intercel·lular. Aquestes vesícules extracel·lulars són capaces de transferir proteïnes, miRNAs i mRNAs de manera encapsulada, tot protegint-los del medi extracel·lular i transportant-los fins a òrgans i indrets del cos allunyats del seu focus de síntesi. En aquesta tesi, utilitzant un model experimental de pancreatitis aguda induïda per taurocolat sòdic en rata, hem avaluat el paper dels exosomes en la propagació de la resposta inflamatòria sistèmica. Els resultats obtinguts indiquen que posteriorment a la inducció de la malaltia hi ha un increment de la concentració d’exosomes circulants, els quals presenten un perfil proteic diferent dels exosomes circulants que hi ha en condicions control. Mitjançant experiments de marcatge i seguiment d’aquestes vesícules hem determinat que els exosomes circulants són capaços de creuar la barrera alveolocapil·lar i d’arribar fins l’espai aveolar, on són captats pels macròfags pulmonars residents. A més, en experiments in vitro es demostra com els exosomes secretats en condicions inflamatòries activen i polaritzen els macròfags cap a un fenotip de tipus proinflamatori. L’anàlisi proteòmic dels exosomes circulants mostra com, durant la pancreatitis aguda severa, aquestes vesícules presenten una gran quantitat de proteïnes sintetitzades majoritàriament pel teixit hepàtic, suggerint que el fetge podria estar secretant nous exosomes i alliberant-los al torrent sanguini en el transcurs de la malaltia. Aquesta hipòtesi va ser reforçada amb nous experiments de marcatge i seguiment dels exosomes, gràcies als quals es va observar com els exosomes generats a la cavitat peritoneal durant la pancreatitis aguda severa són filtrats i retinguts pel teixit hepàtic. En conjunt, els resultats obtinguts reforcen la idea que el fetge tindria un paper central durant la pancreatits aguda i que cal tenir-lo en compte per comprendre quin mecanisme regula l’extensió de la resposta inflamatòria en el transcurs de la malaltia. En tot aquest procés, a més, la lectina REG3-beta podria tenir un paper destacat. Aquesta proteïna d’estrès és una de les més sintetitzades pel pàncrees durant la pancreatitis aguda, la concentració de la qual pot arribar a augmentar fins a 100 vegades durant la fase aguda de la malaltia. La seva funció específica, però, a dia d’avui encara no s’ha descrit ben bé, tot i que se li han atribuït certes propietats antiinflamatòries, mitogèniques i d’opsonització de bacteris. En aquesta tesi es demostra com REG3-beta és capaç d’unir-se a la membrana dels exosomes circulants. A més, hem caracteritzat com aquesta unió depèn del seu domini lectina, i que comporta un bloqueig de la captació de les vesícules per part de les seves cèl·lules diana, impedint que aquestes alliberin els seus mediadors i duguin a terme la seva funció.[eng] Severe acute pancreatitis is an inflammatory disease of the pancreas which progresses accompanied by local and systemic alterations, being lung damage and SIRS the leading causes of death. Despite multiple inflammatory mediators have been detected and described, the pathogenic mechanism of the disease is still unknown. However, over the last few years the discovery of exosomes has revolutionized the field of intercellular communication, since they are able to transfer mediators such as proteins, miRNAs and mRNAs to distant organs. In this work, using an experimental model of taurocholate-induced acute pancreatitis in rats, we evaluated the role of exosomes in the extent of the systemic inflammatory response. Our results indicate that during acute pancreatitis, there is an increase in the concentration of circulating exosomes. By fluorescent exosome tracking in vivo experiments we demonstrate that circulating exosomes are able to cross the alveolocapillary barrier, be phagocyted by alveolar macrophages and polarize them to a proinflammatory phenotype in vitro. The proteomic analysis of circulating exosomes showed that, during acute pancreatitis, exosomes present a large number of proteins synthesized mainly by the hepatic tissue, suggesting that the liver is secreting new exosomes and releasing them into the bloodstream during the course of the disease. This hypothesis was reinforced with new tracking experiments, where we observed that that exosomes generated in the peritoneal cavity during severe acute pancreatitis are filtered and retained by the liver tissue. Overall, these results reveal that the liver would play a central role during severe acute pancreatitis and that it should be taken into account to understand which mechanism regulates the extent of the inflammatory response. The lectine REG3-beta could also play a prominent role in all this process. REG3-beta is the main protein synthesised by the pancreas during acute pancreatitis, the concentration of which can increase up to 100 times. Its specific function has not yet been described, although certain anti-inflammatory, mitogenic and opsonising properties have been attributed to it. In this thesis we demonstrate that REG3-beta binds to the membrane of circulating exosomes and that this interaction depends on its lectin domain. Consequently, this interaction blocks the exosome capture by target cells, preventing them from releasing their mediators and blocking their function

Synthesis of nano Mn-Zn ferrites by gel combustion method with three different fuels and investigation of their structure and properties

The purpose of studying the properties of zinc-manganese nanoferrite was to compare organic fuels that were produced in conditions created by the auto gel combustion method, using citric acid, glycine, and urea with different pH values: (citric acid = 6, glycine = 3 and urea = 0). The samples were prepared in stoichiometric ratios to gain Mn0.5Zn0.5Fe2O4, and all the samples were calcined in the same condition (500 °C and 30 minutes). It should be noted that the entire process of synthesis was photographed to analyze the effect of fuels during the combustion process. Combustion reactions were studied by simultaneous thermal analysis (STA), FT-IR spectroscopy, and X-ray diffraction (XRD), also the Rietveld method was used to determine the type and amount of crystalline phases. Magnetic properties of the samples were measured by vibration sample magnetometer (VSM), and their morphology and powder agglomeration was observed by field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). Superior magnetic properties of the sample synthesized with glycine were achieved. Urea gave the smallest particle size, while citric acid produced intermediate properties

Introduction of nano-laminate Ti3SiC2 and SiC phases into Cf-C composite by liquid silicon infiltration method

The material Cf-C-SiC-Ti3SiC2 is promising for high temperature application. Due to the laminated structure and special properties, the Ti3SiC2 is one of the best reinforcements for Cf-C-SiC composites. In this paper, Cf-C-SiC-Ti3SiC2 composites were fabricated by liquid silicon infiltration (LSI) method; the effect of the TiC amount on the various composites properties were studied. For samples with 0, 50 and 90 vol.% of TiC, the results show that bending strength are 168, 190, and 181 MPa; porosities are 3.2, 4.7, and 9%; the fracture toughness are 6.1, 8.9, and 7.8 MPa∙m1/2; interlaminar shear strength are 27, 36, and 30 MPa; the amount of the MAX phase are 0, 8.5, and 5.6 vol.%, respectively. These results show that amount of TiC is not the main effective parameter in synthesis of Ti3SiC2. The existence of carbon promotes the synthesis of Ti3SiC2 indicating that only sufficient carbon content can lead to the appearance of Ti3SiC2 in the LSI process

High-performance supercapacitor electrode materials based on chemical co-precipitation synthesis of nickel oxide (NiO)/cobalt oxide (Co3O4)-intercalated graphene nanosheets binary nanocomposites

Graphene (Gr)/metal oxide nanocomposites, as advanced electrode materials, have drawn significant attention in supercapacitors due to their two components' synergistic cooperation, which compensates each other's drawbacks and hence perform better than their individual components. In this study, two graphene/metal oxide nanocomposites, Gr/NiO and Gr/Co3O4 binaries were separately synthesized by a co-precipitation method in which NiO or Co3O4 as interlayer spacers were inserted into the graphene structure. The as-synthesized electroactive materials were drop-cast on the as-grown Cu(OH)2 nanowire arrays/Cu substrates fabricated by drenching copper into a rich-alkaline solution. Three-electrode's electrochemical characterizations in 6 M KOH electrolyte showed that Gr/Co3O4 and Gr/NiO exhibit high capacitances of 342.6 and 652 F g−1 at the scan sweep of 5 mV s−1, and 278.5 and 667.58 F g−1 at the current density of 1 A g−1, respectively. In addition, the power density of 250 W kg−1 leads to the energy densities of23.17 and 9.7 Wh kg−1 for Gr/NiO and Gr/Co3O4, respectively. The Gr/NiO with the cyclic stability of 95% has a better electrochemical performance than Gr/Co3O4 (with the cyclic stability of 83%), implying more pseudocapacitance contribution of the NiO nanoparticles embedded within the graphene nanosheets and more efficient synergistic cooperation between these two components. Furthermore, full Gr/NiO/Cu(OH)2/Cu||Gr/NiO/Cu(OH)2/Cu and Gr/Co3O4/Cu(OH)2/Cu||Gr/Co3O4/Cu(OH)2/Cu symmetric cells in the organic electrolyte of 1 M TEA-BF4 in acetonitrile within the potential window of 2 V were also assembled and at 10 mV s−1, exhibited the highest specific capacitances of 32.67 and 24.86 F g−1, respectively.Peer reviewe

Effect of fuel type on the combustion reaction behavior, phase structure and morphology of Ni0.5Co0.5Fe2O4 nanoparticles

Nickel-cobalt ferrite spinels are ferrimagnetic ceramic materials that possess a great potential for application in highdensity magnetic media, recording, color imaging, ferrofluids, and high-frequency devices. A change of their structure from micro- to nano- improves their properties drastically, therefore many methods have been investigated to fabricate nanopowder of these spinels. Gel combustion method is one of them. In this research, Ni0 5Co0 5Fe2O4 nanoparticles were fabricated via gel combustion method using metallic nitrates as an oxidant and citric acid, glycine and urea as fuels and the effects of fuel type on the reaction behavior, structure and morphology of Ni0 5Co0 5Fe2O4 nanoparticles were investigated. The reaction behavior was studied by thermal analysis method (TGA-DTA), crystallite size of powders was characterized by X-ray diffraction (XRD) and their morphology was studied by FE-SEM. The results revealed that the reaction was initiated in urea, glycine and citric at 219 °C, 197 °C, 212 °C, respectively. Samples fabricated from glycine and citric acid had a pure spinel structure but the others fabricated with urea fuel had iron oxide impurity. The crystallite size of nickel cobalt ferrite nanoparticles was in the range of 58 nm to 64 nm and the nanoparticles were agglomerated

Enhancement of dose response and nuclear magnetic resonance image of PAGAT polymer gel dosimeter by adding silver nanoparticles

In the present study, the normoxic polyacrylamide gelatin and tetrakis hydroxy methyl phosphoniun chloride (PAGAT) polymer gel dosimeters were synthesized with and without the presence of silver (Ag) nanoparticles. The amount of Ag nanoparticles varied from 1 to 3 ml with concentration 3.14 g/l, thus forming two types of PAGAT polymer gel dosimeters before irradiating them with 6 to 25 Gy produced by 1.25-MeV 60Co gamma rays. In this range, the predominant gamma ray interaction with matter is by Compton scattering effect, as the photoelectric absorption effect diminishes. MRI was employed when evaluating the polymerization of the dosimeters and the gray scale of the MRI film was determined via an optical densitometer. Subsequent analyses of optical densities revealed that the extent of polymerization increased with the increase in the absorbed dose, while the increase of penetration depth within the dosimeters has a reverse effect. Moreover, a significant increase in the optical density-dose response (11.82%) was noted for dosimeters containing 2 ml Ag nanoparticles

Investigation of Seed Germination Indices for Early Selection of Salinity Tolerant 1 Genotypes: A Case Study in Wheat

Plant establishment is highly correlated with successful germination and seedling growth, the most sensitive and critical stages. Abiotic stresses by their limiting and adverse effects on these stages finally result in poor yield. Therefore, investigating resistance to salinity among genotypes of a desired plant is highly recommended for anticipated drought seasons. To study the effects of salinity on seed germination and initial growth of seedlings, a factorial experiment was conducted based on a completely randomized design with four replicates using three wheat (Triticum aestivum) genotypes (Zagros, Gascogen and Kuhdasht). Salinity levels included 0 (control), 3.5, and 7 dS m-1 (deci-Siemens per meter). The results indicated that salinity had a significant influence on different germination indices (P<0.05). In all the genotypes, with an increase in salinity levels, indices including germination percentage, germination rate, seed vigor, coefficient of germination rate, coleoptile to plumule ratio, and daily germination mean decreased. Unlike the mentioned indices, the ratio of the radicle to plumule and the mean of germination time increased. Zagros genotype showed more tolerant than the other two. Based on these results, it seems that germination indices may be effectively used in selecting tolerant plants to salinity stress.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Effect of Graphene Nanosheets Content on Microstructure and Mechanical Properties of Titanium Matrix Composite Produced by Cold Pressing and Sintering

The effect of graphene nanosheet (GNS) reinforcement on the microstructure and mechanical properties of the titanium matrix composite has been discussed. For this purpose, composites with various GNS contents were prepared by cold pressing and sintering at various time periods. Density calculation by Archimedes&#8217; principle revealed that Ti/GNSs composites with reasonable high density (more than 99.5% of theoretical density) were produced after sintering for 5 h. Microstructural analysis by X-ray diffraction (XRD) and a field emission scanning electron microscope (FESEM) showed that TiC particles were formed in the matrix during the sintering process as a result of a titanium reaction with carbon. Higher GNS content as well as sintering time resulted in an increase in TiC particle size and volume fraction. Microhardness and shear punch tests demonstrated considerable improvement of the specimens&#8217; mechanical properties with the increment of sintering time and GNS content up to 1 wt. %. The microhardness and shear strength of 1 wt. % GNS composites were enhanced from 316 HV and 610 MPa to 613 HV and 754 MPa, respectively, when composites sintered for 5 h. It is worth mentioning that the formation of the agglomerates of unreacted GNSs in 1.5 wt. % GNS composites resulted in a dramatic decrease in mechanical properties