It is shown that the quadrature derivatives in some analytical gradients of energies evaluated with a multi-centre radial-angular grid do not vanish even limit an infinitely dense grid, causing severe errors when neglected. The question are those respect to lattice constant crystal or helical angle chain screw-axis symmetry. This contrast atomic gradients, which can be made arbitrarily small by...

background: different factors such as impression techniques and materials can affect the passive fi t between the superstructure and implant. the aim of this study was to determine the effect of different impression materials and techniques on the dimensional accuracy of implant defi nitive casts. materials and methods: four internal hex implants (biohorizons ø4 mm) were placed on a metal maxil...

Ligating simple amino alcohol or amino ester monomers containing enantiotopic fluorine substituents to the C-terminus of a helical peptide places the fluorine atoms in diastereotopic environments, and gives two distinct and easily identifiable signals in the (19)F NMR spectrum. In the case of a dynamically inverting helix built from achiral monomers, the chemical shift separation between the (1...

An N-terminal L-α-methylvaline dimer induces complete conformational control over the screw sense of an otherwise achiral helical peptide foldamer formed from the achiral quaternary amino acids Aib and Ac6 c. The persistent right-handed screw-sense preference of the helix enables remote reactive sites to fall under the influence of the terminal chiral residues, and permits diastereoselective re...

The planetary flywheel can significantly reduce the weight of flywheel, allowing inerter to be lightweight. When a ball screw inerter-based active actuator is used in vehicle suspension system, nonlinear features affect performance. actuator’s dynamic model constructed this study based on and electromagnetic torque generating mechanism permanent magnet synchronous motor. impact screw–nut fricti...

PURPOSE To present a new intraoral welding technique, which can be used to manufacture screw-retained, mandibular fixed full-arch prostheses. METHODS Over a 4-year period, all patients with complete mandibular edentulism or irreparably compromised mandibular dentition, who will restore the masticatory function with a fixed mandibular prosthesis, were considered for inclusion in this study. Th...

Progressive cavity pumps are used in industry for the circulation of high viscosity fluids, such as crude oil and petroleum products, sewage sludge, oils, salt water, wastewater. Also known single screw pumps, these composed a rotor which has shape rounded screw, moves inside rubber stator. The stator an double helical internal surface which, together with rotor, creates that along rotor. movem...

Conformationally mobile oligomers with helical structures, or 'dynamic foldamers', may populate a mixture of screw-sense conformers whose relative proportion has been used as a means of communicating information on a molecular scale. The dibenzazepinyl urea provides a means of quantifying both the sense and degree of this screw-sense preference through a combination of circular dichroism (CD) a...