Subacute proteome changes following traumatic injury of the developing brain: Implications for a dysregulation of neuronal migration and neurite arborization

Traumatic brain injury (TBI) is a major cause of morbidity and mortality among children and adolescents. To gain insight into developmental events influenced by TBI, we analyzed subacute mouse brain proteome changes in a percussion head trauma model at P7 ipsi- and contralateral to the site of injury. The comparison of brain proteomes of trauma mice and controls revealed reproducible changes in the intensity of 28 proteins (30 protein spots) in response to trauma. The changes detected suggest that TBI leads to apoptosis, inflammation, and oxidative stress. These changes were consistent with our results of histological and biochemical evaluation of the brains which revealed widespread apoptotic neurodegeneration, microglia activation, and increased levels of protein carbonyls. Furthermore, we detected changes in proteins involved in neuronal migration as well as axonal and dendritic growth and guidance, suggesting interference of trauma with these developmental events.     

Effect of different thermal treatments on the mechanical performance of poly(L‐lactic acid) based eco‐composites

PLLA‐based eco‐composites reinforced with kenaf fiber and rice straw and containing red or yellow pigments have been studied. The mechanical behavior of the composites was tested by DMTA at two different annealing temperatures (65°C and 85°C) and times (15 min and 120 min) as well as at two preparation conditions: vacuum drying and long time at room temperature. A decrease of microhardness was observed during the water absorption tests. Moreover, the rice straw‐based composites absorbed more water than the kenaf‐ones. Generally, the dyed NFs composites presented better water resistance than undyed ones. The pigments improved the adhesion and led to better mechanical performance. The natural fibers favored the cold crystallization process of PLLA and shifted the cold crystallization peak temperature to lower values, as it was confirmed by DSC measurements. The values of tensile storage modulus obtained after different preparation condition were strongly affected by the process of physical ageing. According to, tan δ parameter, the samples stored at room temperature for a long time showed the highest amorphous content. The PLLA eco‐composite reinforced with kenaf fibers, dyed with the red pigment, and annealed at 85°C for 2 h displays the best mechanical properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Anti-Idiotype scFv Localizes an Autoepitope in the Globular Domain of C1q

We addressed the issue of C1q autoantigenicity by studying the structural features of the autoepitopes recognized by the polyclonal anti-C1q antibodies present in Lupus Nephritis (LN) sera. We used six fractions of anti-C1q as antigens and selected anti-idiotypic scFv antibodies from the phage library “Griffin.1”. The monoclonal scFv A1 was the most potent inhibitor of the recognition of C1q and its fragments ghA, ghB and ghC, comprising the globular domain gC1q, by the lupus autoantibodies. It was sequenced and in silico folded by molecular dynamics into a 3D structure. The generated 3D model of A1 elucidated CDR similarity to the apical region of gC1q, thus mapping indirectly for the first time a globular autoepitope of C1q. The V_H CDR2 of A1 mimicked the ghA sequence GSEAD suggested as a cross-epitope between anti-DNA and anti-C1q antibodies. Other potential inhibitors of the recognition of C1q by the LN autoantibodies among the selected recombinant antibodies were the monoclonal scFv F6, F9 and A12.     

DSC analysis of crystallization and melting behavior of polypropylene in model composites with glass and poly(ethylene terephthalate) fibers

Isothermal and nonisothermal crystallization of maleic anhydride grafted polypropylene (PP), which is used for the production of split warp knit composite preforms,¹ are analyzed in model composites to determine the influence of reinforcement glass fibers (GF) and poly(ethylene terephthalate) (PET) binding yarns on the crystallization kinetics. Basic energetic parameters of crystallization are determined, and the melting behavior of PP in model composites is analyzed. The crystallization of PP carried out in nonisothermal and isothermal regimes is facilitated in the presence of GF, and the additional effects of PET fibers are also shown. Better conditions for nucleation, resulting in lower energy for formation of a stable nucleus and lower critical dimensions, are proposed as a reason for this. The crystal structure of PP in model composites exhibits lower lamellae thickness and is less disposed to recrystallization. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 239–246, 1999     

Switching azonaphthols containing a side chain with limited flexibility. Part 1. Synthesis and tautomeric properties

A series of azo dyes, possessing amide fragments with restricted flexibility tethered to 4-(phenyldiazenyl)naphthalen-1-ol, was obtained from 1-hydroxy-2-naphthoic acid by subsequent conversion to amides and diazo coupling. It was shown that the position of the tautomeric equilibrium in solution strongly depends on the solvent in both UV and NMR concentration scale. The compounds exist as pure enol forms in chloroform and hydrocarbons, while in polar solvents (acetone, acetonitrile, alcohols) a tautomeric mixture is observed. According to the quantum-chemical calculations the aggregation of the keto tautomer is the possible reason for this shift in the position of the tautomeric equilibrium. To support the theoretical predictions, it was found that from acetone the keto form crystallizes as a dimer with hydrogen bonding between N₁-H in the one molecule and amide CO in the other forming a three-dimensional structure. The importance of the side-chain nitrogen atom on the dimer formation was confirmed by solution and solid state study of 4-(phenyldiazenyl)-2-acetylnaphthalen-1-ol. The results indicate that the new azo-dyes obtained could be suitable candidates for switching and sensing applications in non-polar solvents.     

Natural fiber eco‐composites

The natural fiber (NF) reinforced composites, so called eco‐composites, are subject of many scientific and research projects, as well as many commercial programs. The growing global environmental and social concern, high rate of depletion of petroleum resources, and new environmental regulations have forced the search for new composites and green materials, compatible with the environment. The aim of this article is to present a brief review of the most suitable and commonly used biodegradable polymer matrices and NF reinforcements in eco‐composites, as well as some of the already produced and commercialized NF eco‐composites. POLYM. COMPOS. 28:98–107, 2007. © 2007 Society of Plastics Engineers     

Crystallization behavior of polyhydroxybutyrate in model composites with kenaf fibers

The kinetics of the nonisothermal crystallization process of polyhydroxybutyrate in polyhydroxybutyrate/kenaf fiber model composites (with 80/20 and 70/30 w/w matrix/kenaf fibers) were investigated with differential scanning calorimetry. An analysis of the data was carried out with the Avrami, Ozawa, and modified Avrami and Ozawa models, as well as the Kissinger approach, for the determination of the crystallization activation energy. The Ozawa model was unsuitable for analyzing the nonisothermal data, whereas the other models described these systems very well. By the analysis of all the relevant parameters, the nucleation activity of the kenaf fibers was confirmed. The activation energies from the Kissinger method were evaluated to be 41.2, 32.6, and 26.3 kJ/mol for the pure polymer resin and 80/20 and 70/30 (w/w) polyhydroxybutyrate/kenaf fiber composites, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 804–809, 2006     

Aging effects on gasoline-ethanol blend properties and composition

Blends of 75% gasoline and 25% ethanol (E25) are unique fuels used in Brazil. The natural E25 oxidation process due to aging under atmospheric conditions has been investigated. To evaluate aging effects on the properties of commercially available fuel blends, two samples of regular E25, one sample of regular E25 with additives, and one sample of high octane E25 were tested. The samples were analyzed as new and in aging periods of 30 and 180 days. Fuel density, distillation temperatures T₁₀, T₅₀ and T₉₀, motor and research octane number, as well as concentrations of ethanol, oxygen, olefins, total aromatics, benzene and saturates were evaluated. It was observed an increase of fuel density, distillation temperatures, aromatics and oxygen concentration, and a decrease of the concentration of olefins with aging. The results indicate that the use of aged fuel in automotive engines may increase fuel consumption, carbon deposits formation, carbon monoxide and hydrocarbon emissions.     

Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)‐based biocomposites reinforced with kenaf fibers

Biodegradable thermoplastic‐based composites reinforced with kenaf fibers were prepared and characterized. Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV), produced by bacterial fermentation, was selected as polymeric matrix. To improve PHBV/fibers adhesion, low amount of a proper compatibilizing agent, obtained by grafting maleic anhydride onto PHBV, was added during matrix/fibers melt mixing (reactive blending). When compared with uncompatibilized composites, the presence of the compatibilizer induces a stronger interfacial adhesion and a more pronounced improvement of the mechanical properties. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Tailoring Structure,Composition, and Energy Storage Properties of MXenes from Selective Etching of In‐Plane,Chemically Ordered MAX Phases

The exploration of 2D solids is one of our time's generators of materials discoveries. A recent addition to the 2D world is MXenes that possses a rich chemistry due to the large parent family of MAX phases. Recently, a new type of atomic laminated phases (coined i‐MAX) is reported, in which two different transition metal atoms are ordered in the basal planes. Herein, these i‐MAX phases are used in a new route for tailoriong the MXene structure and composition. By employing different etching protocols to the parent i‐MAX phase (Mo_2/3Y_1/3)₂AlC, the resulting MXene can be either: i) (Mo_2/3Y_1/3)₂C with in‐plane elemental order through selective removal of Al atoms or ii) Mo_1.33C with ordered vacancies through selective removal of both Al and Y atoms. When (Mo_2/3Y_1/3)₂C (ideal stoichiometry) is used as an electrode in a supercapacitor—with KOH electrolyte—a volumetric capacitance exceeding 1500 F cm^?3 is obtained, which is 40% higher than that of its Mo_1.33C counterpart. With H₂SO₄, the trend is reversed, with the latter exhibiting the higher capacitance (≈1200 F cm^?3). This additional ability for structural tailoring will indubitably prove to be a powerful tool in property‐tailoring of 2D materials, as exemplified here for supercapacitors.