A 13C chemical shifts study of iodopyrazoles: experimental results and relativistic and non-relativistic calculations

Structural Chemistry - This work reports the 13C chemical shifts of 49 iodopyrazoles and the 15N chemical shifts of 6 iodopyrazoles, most of them from the literature but a number of significant...     

Simultaneous detection of Mn,Co, Ni,and Cu using ion chromatography coupled with ICP-MS with a special focus on the determination of 59Ni in corrosion deposits

Journal of Radioanalytical and Nuclear Chemistry - A simple method for the simultaneous detection of stable and long-lived Mn, Ni, Co and Cu isotopes has been created by coupling an ion...     

The Assignment of Long-Range 13C-1H Coupling Constants in Pyrazoles 13C NMR,Selective Decoupling

Although quite a few papers have been devoted to the ¹³C NMR study of pyrazoles, there is one problem that has not yet been satisfactorily solved, namely the assignment of the ²JCH and ³JCH coupling constants. In general, the ³C chemical shifts and ¹JCH coupling constants can be easily attributed, but the assigment of the long-range ²JCH and ³JCH coupling constants is not straight forward. In N- substituted pyrazoles, where annular tautomerism is prevented, each carbon atom can have two long-range coupling constants with the ring protons.     

A Photoelectron Spectroscopic Study of the 2-Azidopyridine ⇋ Tetrazolo [1.5-α]Pyridine Equilibrium between 391 and 533 K

The azido/tetrazole equilibrium has been widely examined^1,2,3 but most of the studies concern the solid state and the solution. The publications dealing with the vapour phase are rare and contain only qualitative information obtained either by IR or MS. However, it is clearly established that the azido form is stabilized at high temperatures. In the particular case of 2-azidopyridine I, according to ¹H NMR and IR data, the equilibrium lies strongly on the side of the tetrazole II in solution.^3,4 In the vapour phase at high temperature, mass spectrometry,⁵ IR,⁶ and the nature of compounds obtained by gas phase pyrolysis^7,8 of tetrazolo [1,5-α]pyridines, shown that the azide form is favoured in those conditions.     

Implementing PLS for distance-based regression: computational issues

Distance-based regression allows for a neat implementation of the partial least squares recurrence. In this paper, we address practical issues arising when dealing with moderately large datasets (n ~ 10⁴) such as those typical of automobile insurance premium calculations.     

Plated and Intact Femur Strains in Fracture Fixation Using Fiber Bragg Gratings and Strain Gauges

This paper presents an experimental methodology to determine plated and intact femur strains using fiber Bragg gratings and strain gauges. A plated and an intact synthetic femur were used and loaded under a simplistic static load of 600 N. A stainless steel (316L) plate was used to fixate a simulated 45° fracture on one femur. Strains were recoded at the same sites on both femurs. Strain shielding is shown to be more pronounced at the distal region of the plated femur. The experimental methodology based on fiber Bragg grating sensors is a novel approach to assess bone plate strains, which could also be used to obtain biologic tissue and implant surface strains in locations where conventional strain gauge use is not technically feasible.     

A Facile Method to Determine the Absolute Structure of Achiral Molecules: Supramolecular‐Tilt Structures

Achiral compounds 4‐methoxy‐4‐(p‐methoxyphenyl)cyclohexanoneethylene ketal ( 2 ), 4‐hydroxy‐4‐(p‐methoxy phenyl)cyclohexanoneethylene ketal ( 3 ), and 3,5‐dimethyl‐4‐nitropyrazole ( 4 ) crystallized in chiral structures and the samples showed an enantiomeric excess. We have determined the absolute structures of these compounds by using X‐ray diffraction with copper radiation at low temperatures. Moreover, we have also established the prevalent absolute structures in these samples, by comparing their calculated and solid‐state vibrational circular dichroism (VCD) spectra. The consistency of this method was confirmed by using (R,R)‐2,8‐diiodo‐4,10‐dimethyl‐6 H,12H‐5,11‐methano‐dibenzo[b,f][1,5]diazocine, Tröger′s base, (R,R)‐ 1 , as a chiral compound of known absolute configuration.