Relation between formation rates of methane and hydrogen on pyrolysis of coal under pressure

In an earlier paper¹ it became clear that secondary-methane formation occurs under certain experimental conditions during pyrolysis of coal. In order to study this more deeply, the evolution rates of methane and hydrogen were measured simultaneously for an anthracite and a lignite. The secondary-methane formation was accompanied by a corresponding decrease in hydrogen formation. It is suggested that secondary-methane formation occurs according to the equation C + 2H₂ = CH₄ on an average and is proportional to the partial pressure of evolved hydrogen.     

Structure and oxidation resistance of plasma sprayed Ni–Si coatings on carbon steel

Ni–Si coatings consisting of mainly NiSi₂ and NiSi were deposited on a carbon steel by air plasma spraying. Isothermal oxidation tests of the carbon steel substrates with the Ni–Si coatings at 500–800 °C have been carried out. The result indicated that a protective SiO₂-based oxide scale was formed on the surface of the coatings after oxidation. On the other hand, during oxidation, phase transformation occurred among the NiSi₂, NiSi and Ni₂Si phases constructing the Ni–Si coatings. This was caused by the extraction of silicon from the silicides and the reformation of silicides at the silcide/Si-blocks interface. Above 700 °C, the outward diffusion of iron and carbon became very fast and consequently decarburization happened at the coating/substrates interface, which induced the formation of pores in the substrates near the interface. In addition, grain boundary oxidation of Cr in the steel substrate was observed above 700 °C.     

Fractional Invariance Principle

Abstract. The paper presents a central limit theorem and an allied invariance theorem related to what Marinucci and Robinson [Journal of Statistics, Planning and Inference (1999) Vol. 21, pp. 111–122] termed type II fractional Brownian motion. To widen the applicability, their independent and identically distributed (i.i.d.) assumption for the innovation process is relaxed, allowing it to be mildly conditionally heteroscedastic and requiring the Martingale‐difference property only asymptotically. Additionally, the paper presents, for contrast, the weak convergence of the conventional partial sum process in a related set‐up.     

Nanocrystalline Ge synthesis by the chemical reduction of hydrothermally grown Si0.6Ge0.4O2

Previously, we have reported the use of high pressure oxidation techniques for the growth of compositionally congruent oxides from Si_1−xGe_x. We have now used this technique as part of a two-step process of oxidation at 25 MPa and 475°C followed by reduction in 0.1 MPa (1 atm) H₂ at 700-850δC for the synthesis of nanocrystalline Ge precipitates. Using transmission electron microscopy, we show that the proposed method produces a dispersion of fine (<10 nm) precipitates of Ge embedded in an SiO₂ matrix. The structure of the oxide prior to reduction with H₂ was investigated with Fourier transform infrared spectroscopy which reveals SiO₂, GeO₂, SiO, Si-O-H, and Ge-O-H bonding states in the glass. In this paper, we discuss the thermodynamics and kinetics of both the hydrothermal oxidation technique and the proposed Ge nanocrystalline synthesis process.     

Metalation states versus enzyme activities of Cu, Zn-superoxide dismutase probed by electrospray ionization mass spectrometry

Cu, Zn-superoxide dismutase (SOD-1), an enzyme that catalyzes the disproportionation reaction of superoxide to produce oxygen and hydrogen peroxide, thereby protecting cells from oxidative stress, is a homodimer that coordinates one copper and one zinc ion per monomer. Cu (2+) and Zn (2+) ions play important roles in enzyme activity and structural stability, respectively. In addition, dimer formation is also essential for fulfilling the function of SOD-1. We here report on the reconstitution and enzyme activities of several metalation states of SOD-1 (Cu 4-, Cu 3Zn-, and Cu 2Zn 2-homodimers). Each metalation state of the reconstituted SOD-1 could be unambiguously differentiated by electrospray ionization mass spectrometry, the metal ions of which had been completely replaced by 99 atom % (63)Cu and (68)Zn stable isotopes. It was found that (1) the Cu 4-dimer possessed 84% of the activity of the native enzyme, (2) the Cu-site resisted being coordinated with Zn (2+) ions while the Zn-site could be bound with Cu (2+) ions, and (3) the simultaneous addition of the Cu (2+) and Zn (2+) ions to generate a fully metalated form produced the multiply metalated SOD-1 (Cu 4-, Cu 3Zn-, and Cu 2Zn 2-dimers), which were clearly distinguishable from one another by the use of the stable isotopes, while the sequential addition of Zn (2+) followed by the Cu (2+) ion predominantly produced a Cu 2Zn 2-dimer comparable to the native enzyme.     

High-pressure atom transfer radical polymerization of methyl methacrylate for well-defined ultrahigh molecular-weight polymers

The feasibility of high-pressure atom transfer radical polymerization (ATRP) for synthesizing well-defined polymers of extraordinarily high molecular weights was demonstrated. ATRP of methyl methacrylate (MMA) under pressures up to 500 MPa was investigated at 60 °C. The addition of a small amount of a Cu(II)Cl₂/ligand complex along with the general benefits of high pressure of enhancing propagation and suppressing termination brought about an excellent control of polymerization even with an extremely low concentration of ATRP initiator. For example, there was produced PMMA with a number-average molecular weight M_n of 3.6 × 10⁶ and a polydispersity index of 1.24, which had never been achieved by conventional ATRP.     

Accurate modeling of dielectric interfaces by the effective permittivities for the fourth-order symplectic finite-difference time-domain method

The fourth-order finite-difference time-domain (FDTD) method using a symplectic integrator propagator can calculate the propagation of the electromagnetic waves with very low dispersion error in the region of a constant or smoothly varying index profile. An additional technique is required for the problem with the discontinuous dielectric interfaces. We derived the third-order effective permittivities at dielectric interfaces for the fourth-order FDTD method in the case of 2D TE polarization. As the required accuracy level is increased, the memory resources used by the fourth-order FDTD method with the effective permittivities are reduced severalfold or more compared with the standard FDTD method. The accurate performance of the proposed method is demonstrated through numerical examples.     

Production of nanopatterns by a combination of electron beam lithography and a self-assembled monolayer for an antibody nanoarray

We report on a flexible method of producing antibody (IgG) nanopatterns by combining electron beam (EB) lithography and a perfluorodecyltriethoxysilane (FDTES) self-assembled monolayer (SAM). Using EB lithography of the FDTES SAM, we easily fabricated IgG patterns with feature sizes on the order of 100 nm. The patterned IgG retained its ability to interact specifically with an anti-LgG. The influence of different concentrations of the IgG and anti-IgG on the resulting fluorescent IgG arrays was investigated. These IgG nanopatterns appeared to be remarkably well controlled and showed almost no detectable nonspecific binding of proteins on a hydrophobic SAM under a suitable incubation condition, characterized by atomic force microscopy, and epi-fluorescence microscopy. The technique enables the realization of high-throughput protein nanoscale arrays with high specificity.