Much attention has been devoted to predicting and controlling fracture toughness in ferrous weldments. Extensive studies relat ing toughness with welding parameters and weldment composit ion have been made. All such studies have sought to define the important variables affecting toughness. Unfortunately, such studies often resulted in linear regressions of one variable against toughness, fractu...

The series of methyl halides, CH(3)X (X = F, Cl, Br, and I), is prototypic for demonstrating the s.c. normal halogen dependence of light-atom nuclear magnetic resonance shielding constants in the presence of halogen atoms of varying electronegativity. We report a systematic experimental and first-principles theoretical study of the (13)C and (1)H shielding tensors in this series. The experiment...

A counterintuitive gauge-dependence of NMR shieldings for rare-gas dimers is presented and analyzed. It is shown that common belief about the existence of a natural gauge-origin for spherical atoms with respect to NMR shielding calculations is wrong.

Hartree-Fock (HF) and Density Functional Theory (DFT) methods employed to study the effect of conformational change on the 13C chemical shifts of 6-mono axial and equatorial substituted and 6,7-di axial-axial, equatorial-equatorial and axial-equatorial substitutedderivatives of 5,6,7,8-tetrahydrodibenzo[a,c]cyclo-octene. The geometry of the conformers have been optimized...

Gas tungsten arc welding (GTAW), also known as tungsten inert gas (TIG) welding, is an arc welding process that uses a nonconsumable tungsten electrode to produce the weld. The weld area is protected from atmospheric contamination by a shielding gas (usually an inert gas such as argon), and a filler metal is normally used, though some welds, known as autogenous welds, do not require it. A const...

INTRODUCTION is attributable to the parietal distribution of the vacuoles within the cells of the particular strain of blue-green alga used in these experiments . Gas vacuoles are small, cylindrical, gas-filled vesicles which occur in certain procaryotic cells . They are found in numerous blue-green algae, many photosynthetic bacteria, some halophilic bacteria, and some planktonic freshwater ba...

Nuclear spin relaxation provides detailed dynamical information on molecular systems and materials. Here, first-principles modeling of the chemical shift anisotropy (CSA) relaxation time for the prototypic monoatomic (129)Xe gas is carried out, both complementing and predicting the results of NMR measurements. Our approach is based on molecular dynamics simulations combined with pre-parametrize...

A main problem raised by arc welding manufacturing is the determination of the optimal process parameters to ensure weld quality as well as resource efficient and sustainable production. To address this problem a better process understanding is required. In this study thermal magneto hydrodynamic modeling of a welding arc is used to reach a deeper insight into the influence of the composition o...

The chemical shielding is the most familiar and universal parameter in the field of nuclear magnetic resonance (NMR). It may be calculated or measured experimentally; it may be studied by gas phase, liquid phase, or solid phase NMR, as well as by quantum mechanical methods. This chapter will introduce NMR both from a theoretical and an experimental standpoint, and quantum theory. The following ...