Reaction of cyclohexanone with [NH4]+ under chemical ionization conditions. 1—formation of protonated unsubstituted imines

High resolution and metastable decomposition spectra of the ions [M + NH₄]⁺ (and [M + ND₄]⁺) formed by reaction of [NH₄]⁺ (and [ND₄]⁺) with cyclohexanone have been measured. The results provide evidence that the m/z 98 ion, which is abundant in the chemical ionization (NH₃) spectrum of cyclohexanone, is in fact composed of two isobaric ions: a protonated imine ion and the molecular ion of cyclohexanone. The former is formed by a mechanism analogous to that occurring in solution.     

The neuroblast and angioblast chemotaxic factor SDF-1 (CXCL12) expression is briefly up regulated by reactive astrocytes in brain following neonatal hypoxic-ischemic injury

Background  

Stromal cell-derived factor 1 (SDF-1 or CXCL12) is chemotaxic for CXCR4 expressing bone marrow-derived cells. It functions in brain embryonic development and in response to ischemic injury in helping guide neuroblast migration and vasculogenesis. In experimental adult stroke models SDF-1 is expressed perivascularly in the injured region up to 30 days after the injury, suggesting it could be a therapeutic target for tissue repair strategies. We hypothesized that SDF-1 would be expressed in similar temporal and spatial patterns following hypoxic-ischemic (HI) injury in neonatal brain.     

Elucidation de structure et comportement de produits naturels sous ionisation chimique—I: Mise en evidence de la cinerubine a par etude des decompositions unimoleculaires des ions produits en phase gazeuse par iBu+

Positive ion chemical ionization mass spectrometry by ⁱBu⁺ is used to determine the structure of anthracycline 4915 A. The metastable decompositions of protonated molecular ion (m/z 828) and fragment ions (aglycone and sugar moieties) show that the antibiotic in cinerubine A. Unimolecular decompositions occuring in the first field-free region are detected by “Linked Scan méthods” B/E and B²/E.     

Search for a Δ++ presence in the 3He nucleus by means of the 3He (p,t) Δ++ reaction

The reaction ³He (p, t) Δ⁺⁺ has been studied to look for evidence of (Δ⁺⁺, 2n) components of the ³He wave function. The experimental conditions, proton energy and triton angles, have been chosen to emphasize such components.     

The Pauson–Khand Mechanism Revisited: Origin of CO in the Final Product

The mechanism of the Pauson–Khand reaction has been studied by mass spectrometry and it has been found, through ion‐molecule reaction with ¹³CO, that the carbon monoxide incorporated into the product cyclopentenone is one that has been retained within the complex. Theoretical and kinetic calculations support this finding, which provides a complementary explanation for the effect of Pauson–Khand promoters.