Rat mature sympathetic neurones derive neurotrophin 3 from peripheral effector tissues

In a previous study we have demonstrated that endogenous neurotrophin 3 (NT3) is required for the survival of most sympathetic neurones in postnatal rats. However, the mechanisms underlying the action of NT3 on sympathetic neurones is not known. Neither is it understood whether NT3 is retrogradely transported from peripheral tissues or acts locally in an autocrine fashion. In the present study, NT3-mRNA was quantified in sympathetic effector tissues and NT3 protein was localized in intact and lesioned sympathetic nerves in rats. NT3-mRNA is expressed and developmentally regulated in many effector tissues including mesenteric arteries, salivary gland, heart and kidney but hardly detectable in the superior cervical ganglia of adult animals. The majority of sympathetic neurones express immunoreactivity for TrkA and TrkC in both neonatal and adult rats. Sympathetic somata are normally immunoreactive for NT3, but the immunoreactivity is abolished by systemic administration of NT3 antibodies or axotomy of postganglionic neurones, suggesting an accumulation of NT3 from extraneuronal sources. Furthermore, the detection of NT3-immunoreactivity in the internal carotid nerve as early as 3 h following a compression and only on the distal side indicates endogenous NT3 is retrogradely transported by sympathetic neurones. These studies provide evidence indicating that NT3, like nerve growth factor, is an effector tissue-derived neurotrophic factor for sympathetic neurones both during development and in the adult animal. Thus, we have provided a clear example that one type of neurone derives, through a retrograde transport mechanism, two neurotrophic factors simultaneously from its peripheral effector tissues.     

Fatigue and Fracture Behavior of a Ca-Based Bulk-Metallic Glass

The compression and fatigue behavior of a Ca₆₅Mg₁₅Zn₂₀ bulk-metallic glass (BMG) was studied in air at room temperature. During the preparation of cubical samples of the Ca₆₅Mg₁₅Zn₂₀ for compression and fatigue investigations, small spherical cavities were found. Under both monotonic and cyclic compression loadings of the samples, fractures initiated at these cavities and propagated in a direction generally parallel to the loading axis. Finite-element analysis (FEA) was used to model the fracture behavior. The FEA of a centrally located spherical void showed that under compression loading, large tensile stresses evolved in the cavities. The orientation of the maximum principal stress (P1) was found to be normal to the direction of crack propagation, which is consistent with the experimental finding. Stresses in deeply embedded adjacent voids and those in superficial voids were also studied. The influence of the void location in the cubical sample on the fracture behavior was quantitatively discussed.     

Corrosion Behavior of Fe<Subscript>41</Subscript>Co<Subscript>7</Subscript>Cr<Subscript>15</Subscript>Mo<Subscript>14</Subscript>C<Subscript>15</Subscript>B<Subscript>6</Subscript>Y<Subscript>2</Subscript> Bulk Metallic Glass in Sulfuric Acid Solutions

An Fe₄₁Co₇Cr₁₅Mo₁₄C₁₅B₆Y₂ bulk metallic glass with a diameter of 5 mm was prepared with the copper-mold-casting method. The corrosion resistance of this amorphous steel in sulfuric-acid solutions was determined by electrochemical measurements. The passive film formed on the surface of the alloy after immersion in the 0.5-mol/l H₂SO₄ solution for 1 week was analyzed by X-ray photoelectron spectroscopy (XPS). Electrochemical measurements show that the corrosion resistance of the amorphous steel in the 1 mol/l-H₂SO₄ solution is superior to a stainless steel (SUS 321), and is almost the same as Ti6Al4V, which shows that the amorphous steel has an excellent corrosion resistance in sulfuric-acid solutions. As the concentration of the sulfuric-acid solutions increases from 0.5 mol/l to 4 mol/l, the corrosion resistance of the amorphous steel decreases. The XPS result reveals that a bilayer structure of protective film formed on the surface of the amorphous steel in a H₂SO₄ solution. The compositions of the inner part of the film are MoO₂, Cr₂O₃, CoO, and FeO, and those of the outer film are MoO₃, Cr(OH)₃, Co(OH)₂, and Fe(OH)₃.     

Effect of Praseodymium on Superconductivity and Magnetism in Y1–xPrxBa2Cu4O8 Prepared by Nitrite Pyrolysis Method

X-ray diffraction patterns show that most samples of Y_1-x Pr_xBa₂Cu₄O₈ examined in the present study contained a single YBa₂ Cu₄O₈ (1-2-4) superconductive phase for x<0.7.Lattice parameters a and b increased with Pr concentration, suggesting that most of the Pr is trivalent in Y_1-x Pr_x-Ba₂Cu₄O₈. The zero-resistance temperature, T _co, decreases monotonically from 80 K at x=0 to 12 K at x=0.65, and superconducting transition widths tend to broaden for x>0. The room-temperature resistivity changes linearly until x=0.7 and increases abruptly at x=-0.75. The critical concentration, x_cr, thus was estimated to be 0.7. The effective magnetic moments of Pr in Y _1-x Pr_xBa₂Cu₄O₈ were 3.63., 3.35, and 3.23, μ_B for x=0.2, 0.4 and 0.6, respectively. In the R_0.8 Pr_0.2Ba₂Cu₄O₈ system, the depression of T_c weakly depends on the ionic radius of rare-earth elements. Similarities and differences between Y _1-x Pr_xBa₂Cu₄O₈ and Y_1-xPr_x-Ba₂Cu₃O_7-y also were noted and are discussed in this paper.     

Plasmonic Fano resonance and dip of Au-SiO2-Au nanomatryoshka

This study theoretically investigates Fano resonances and dips of an Au-SiO₂-Au nanomatryoshka that is excited by a nearby electric dipole. An analytical solution of dyadic Green''s functions is used to analyze the radiative and nonradiative power spectra of a radial dipole in the proximity of a nanomatryoshka. From these spectra, the plasmon modes and Fano resonances that accompany the Fano dips are identified. In addition, the scattering and absorption spectra of a nanomatryoshka that is illuminated by a plane wave are investigated to confirm these modes and Fano dips. Our results reveal that a Fano dip splits each of the dipole and quadrupole modes into bonding and anti-bonding modes. The Fano dip and resonance result from the destructive interference of the plasmon modes of the Au shell and the Au core. The Fano factors that are obtained from the nonradiative power spectra of the Au shell and the Au core of a nanomatryoshka are in accordance with those obtained from the absorption cross section spectra. Moreover, these Fano factors increase as the plasmonic coupling of the Au shell with the core increases for both dipole and quadrupole modes.     

Ordered mesoporous silica prepared by quiescent interfacial growth method - effects of reaction chemistry

Acidic interfacial growth can provide a number of industrially important mesoporous silica morphologies including fibers, spheres, and other rich shapes. Studying the reaction chemistry under quiescent (no mixing) conditions is important for understanding and for the production of the desired shapes. The focus of this work is to understand the effect of a number of previously untested conditions: acid type (HCl, HNO₃, and H₂SO₄), acid content, silica precursor type (TBOS and TEOS), and surfactant type (CTAB, Tween 20, and Tween 80) on the shape and structure of products formed under quiescent two-phase interfacial configuration. Results show that the quiescent growth is typically slow due to the absence of mixing. The whole process of product formation and pore structuring becomes limited by the slow interfacial diffusion of silica source. TBOS-CTAB-HCl was the typical combination to produce fibers with high order in the interfacial region. The use of other acids (HNO₃ and H₂SO₄), a less hydrophobic silica source (TEOS), and/or a neutral surfactant (Tweens) facilitate diffusion and homogenous supply of silica source into the bulk phase and give spheres and gyroids with low mesoporous order. The results suggest two distinct regions for silica growth (interfacial region and bulk region) in which the rate of solvent evaporation and local concentration affect the speed and dimension of growth. A combined mechanism for the interfacial bulk growth of mesoporous silica under quiescent conditions is proposed.     

Ozonation of Pyrolytic Aqueous Phase: Changes in the Content of Phenolic Compounds and Color

Ozonation on the phenols present in pyrolytic aqueous phases attained from biomass thermochemical conversion was evaluated. During ozonation, the dark color of original samples was found to decrease as a function of ozonation time. The oxidation kinetics of phenols was quantified by a method based on the color changes of samples. The oxidation profiles showed different behaviors and in some cases the phenols presented a positive correlation with the relative R color parameter, except eugenol, syringol, and vanillin which were markedly different. Finally, the color changes observed seem to be associated with the changes in the overall content of phenols and with the change in the molecular weight of the heavy fractions that include lignin oligomers.     

MONITORING THE HYDROGEN RELEASE FROM COAL LIQUID SOLVENTS USING A HYDROGEN PROBE

A hydrogen probe made of nickel tubing has been used to monitor the release of hydrogen from coal liquid solvents at elevated temperatures and pressures. A knowledge of this release rate is helpful in determining the overall hydrogen balance for coal liquefaction operations, in choosing among alternative solvents and in evaluating the validity of model compounds. The hydrogen release was found for coal liquids to reach a constant value when the reactor temperature was steady. In the case of some model compounds the amount of hydrogen released continued to increase and equilibrium was not attained during a 10 hours measurement period. For the coal liquids the total pressure of the system was found to increase sharply with time indicating the production of gases other than hydrogen, while for the model compounds the total pressure increases were almost parallel to the increases of the hydrogen partial pressure. A correlation was developed for the percentage of hydrogen released with the aromatic fraction distribution in the coal liquids. The hydrogen probe was a valuable instrument for continuously following the hydrogen changes in these dehydrogenation experiments.