The thermoelectric power of the metallic glass Ca0.8Al0.2

We report the first measurement of the thermoelectric power Q, of a metallic glass that contains only normal metals. The thermoelectric power of amorphous Ca_0.8Al_0.2 has been measured as a function of temperature from 10 K to 420 K. It is found that Q is positive, varies linearly with temperature and has a small slope. This is similar to the thermoelectric power found for other metallic glasses containing large concentrations of transition metal atoms.     

Two particle rapidity correlation in proton-emulsion nucleus interactions at 400 GeV

We present a study of two-particle correlations in proton-emulsion nucleus reactions at 400 GeV. In particular the correlations at different nuclear excitations and different rapidity regions are treated. Positive correlations, depending on nuclear excitation, are observed in the rapidity region η<1.5.     

Interstitial site of Cu in Ca

Fluorescence EXAFS was used to study the siting of a dilute solution of Cu in Ca. The Cu is interstitial in Ca, and no more than .4Å away from the center of the octahedral site. No lattice dilation was seen about the Cu atom, even though Cu is “too big” to fit into the interstitial site.     

Marangoni convection in weld pools with a free surface

A steady-state two-dimensional model of heat transfer and fluid flow was developed to describe Marangoni convection in the weld pool. Both the pool surface and the fusion boundary were calculated. The validity of the model was verified against an asymptotic solution for Marangoni-convection-induced free surface geometry. Two different cases were studied, i.e. a negative surface tension temperature coefficient ?γ/?T a positive one, and the resultant shapes of the weld pool surface were compared.     

Polyarylates (I): Investigation of the interfacial polycondensation reaction by UV

The interfacial polycondensation of bisphenol A with isophthaloyl chloride and terephthaloyl chloride in dichloromethane with triethylbenzylammonium chloride as the catalyst was described. A well-defined two-phase system had been observed, so the concentration of bisphenolate in the aqueous phase could be determined by UV spectrometer. The conversion was found to increase rapidly with reaction time, but the rate of increase in molecular weight was slow. At the initial stage with conversion up to 95%, the reaction proceeded similarly to that of solution polycon-densation because the synthesized polyarylate could be dissolved in dichloromethane, and a polymer with a low molecular weight resulted. At the final stage of the reaction, the molecular weight was increased to a very high value due to the local concentration effect. The mole ratio of bisphenol A to diacid chlorides was found to affect the molecular weight very much. In the case of a mole ratio less than 1, the reaction remained in the initial stage mostly, and the molecular weight was low. However, for a mole ratio greater than 1, polyarylate with a very high molecular weight could be obtained because the local concentration effect was much more significant owing to the high concentration of bisphenolate that remained in the aqueous phase at the final stage.     

Polyarylates. IV. Synthesis of block copolymers via two-step interfacial polycondensation

A new method for preparing block copolyarylates via two-step interfacial polycondensation is proposed. First, oligomers with acid chloride end groups were obtained from interfacial polycondensation with a mole ratio of bisphenol A to diacid chloride(s) less than I. In the second step, two reaction systems containing various oligomers were mixed thoroughly and more bisphenolate was charged into this mixture. The synthesis of the block copolyarylates was justified from the viewpoint of statistics, and of differences in molecular weight between oligomers and block copolymers. These block copolyarylates could be differentiated from polyarylates through crystal-line behavior and solubility in m-cresol analyses.     

Mass spectra of aryl substituted N-t- butylbenzamides: Substituent effects on unimolecular ion decomposition

The major reactions of aryl substituted N-t-butylbenzamides upon electron-impact involve direct cleavage of a methyl radical, the loss of a butene molecule with the transfer of one hydrogen, or the loss of a butenyl radical with the transfer of two hydrogens. The last of these processes parallels the mass spectral behavior of aliphatic amides. Substituent effects indicate that electron-withdrawing groups on the aromatic ring enhance the two hydrogen transfer process, while electron-donating groups enhance the single hydrogen transfer process. Ion abundances, ionization potentials and appearance potentials are discussed with respect to correlation with σ⁺ values.