Materials Literature
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Studies on the dissolution of stressed crystals have shown that stress corrosion can lead to roughening of interfaces. The corrosion pattern develops due to gradients in elastic energy along a free crystal surface with an initial roughness. Dissolution will cause further increase in elastic energy, which in turn will…
The types of damage to sample surfaces that can occur during x-ray or electron irradiation used during Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS) are summarized. The material and instrumental dependence of the rate and nature of damage formation or sample degradation are highlighted.…
Abstract This paper describes a method for evaluating the kinetic constants in a rate expression for catalytic combustion applications using experimental light‐off curves. The method uses a transient one‐dimensional single channel monolith finite element reactor model to simulate reactor performance. The heat and mass…
Abstract Alternating poly(amide urea)s from ε-caprolactam, diamines H 2 N-(CH 2 ) x - NH 2 (x = 2 - 4), and diphenyl carbonate were prepared in two steps. The microstructure of the poly(amide urea)s, as determined by means of 1 H NMR spectroscopy, reveals a strictly alternating sequence of the building blocks. The mol…
The role of KOH in the one-stage KOH-activation of rice straws was studied using FTIR, XPS, TGA, and DTG techniques. It was found that at the impregnation, KOH extracts to some extent the lignin component from rice straw and reacts with hydroxyl groups. On heat-treatment, the impregnated KOH facilitates intermolecular…
Abstract The type B structure of the single rare earth element disilicates has been revised using room temperature and pressure single-crystal X-ray diffraction measurements on Gd 2 Si 2 O 7 , Tb 2 Si 2 O 7 and Ho 2 Si 2 O 7 synthesized at 2–2.5 GPa, 1400–1500 °C in a piston-cylinder apparatus and Dy 2 Si 2 O 7 synthe…
This paper describes a method of studying and modeling the dielectric relaxation for stationary power apparatus in an interconnected network to get the necessary aging indicators. The polarization phenomenon was studied using Recovery Voltage (RVM) and Polarization Current (PCM) Measurements on individual power appara…
Tyrosine hydroxylase (TyrH) catalyzes the hydroxylation of tyrosine to dihydroxyphenylalanine. In the proposed mechanism, a ferryl-oxo species attacks the aromatic ring of tyrosine, forming a cationic intermediate. However, no significant isotope effect is found for wild-type TyrH when 3,5-2H2-tyrosine is used as a su…
The synthesis of novel bis-axially coordinated ruthenium(II) complexes with tetra-15-crown-5-phthalocyanine and N-donor ligands ( R 4 Pc ) Ru ( L 2 ) ( R 4 Pc 2- = 4,5,4',5',4'',5'', 4''',5'''- tetrakis(1,4,7,10,13-pentaoxotridecamethylene)phthalocyaninate-ion, L = pyridine (py), isoquino-line (iqnl), triethylamine (…
Stable icosahedral quasicrystals have been synthesized in the Sc–Cu–Zn system by quench-and-anneal or in-situ filtration methods. These have a composition near Sc16.2(3)Cu12.3(3)Zn71.5(6) at 480°C with a quasilattice constant of 4.995 6(7) Å determined by the Elser method from a single-phase Guinier pattern. An electr…
6F-Polyimides with a phenylethynyl endcap (HFPE) were fabricated into carbon fiber composites using the standard polymerization of monomer reactant (PMR) approach via the ester/acid route. T650-35/HFPE carbon fiber composites were evaluated against the corresponding T650-35/PMR-II-50 composites with nadic endcap at 31…
Strong blue emission is observed from Ti-doped MgAl 2 O 4 , yellow emission from a Mn-doped one and white light emission from a V-doped one. The optimum condition to obtain the strongest emission was studied by changing the doping density and growing atmosphere. The microscopic models for these emission processes are…
We have developed a new formulation of the coupled-wave method (CWM) to handle aperiodic lamellar structures, and it will be referred to as the aperiodic coupled-wave method (ACWM). The space is still divided into three regions, but the fields are written by use of their Fourier integrals instead of the Fourier series…
Abstract Polypropylene homopolymer melts containing up to 50 percent by weight of talc filler (24 vol%) were tested on a Gottfert Rheotens melt strength testing unit. Melt strength and drawability parameters were measured from these tests to evaluate changes in the extensional behavior of the melt induced by filler ad…
AISI type 304L stainless steel (SS) was assessed for its corrosion resistance in nitric acid solution. The effect of variation in nitric acid concentration (1 to 10N) and temperature (298 K, 313 K, 333 K, 348 K) on the corrosion resistance of 304L SS was investigated using potentiodynamic polarisation studies. The cor…
Both lighter- and hydrophobic heavier-than-liquid particles will float on liquid–air surfaces. Capillary forces cause the particles to cluster in typical situations identified here. This kind of clustering causes particles to segregate into islands and bands of high concentrations in thin liquid films rimming the insi…
Tensile strength and creep behavior of a two‐dimensional (2D) laminate carbon–carbon composite (C/C) were examined from room temperature to 2773 K in an inert atmosphere. The tensile strength of the C/C was monotonically enhanced with increasing test temperatures. In particular, significant improvement was observed at…
This paper compares the processability, mechanical properties, and water absorption behavior of polypropylene (PP) composites filled with white rice husk ash (WRHA) and silica. It is shown that preparation of WRHA filled composites requires less energy than silica filled composites. WRHA-PP composites exhibit better i…
Protein farnesyltransferase (FTase) catalyzes the addition of a farnesyl chain onto the sulfur of a C-terminal cysteine of a protein substrate. Magnesium ions enhance farnesylation catalyzed by FTase by several hundred-fold, with a KMg value of 4 mM. The magnesium ion is proposed to coordinate the diphosphate leaving…
Filmes finos de quitosana (média massa molecular) foram produzidos a partir de soluções precursoras em diversas concentrações e caracterizados com respeito à estrutura e grau de absorção de água. Os filmes foram obtidos por adsorção sobre lâminas de vidro previamente funcionalizadas (técnica de automontagem). Análises…