Towards an unified chemical model of secondary bonding.

The concept of secondary bond covers a wide range of non-covalent interactions involving an acceptor (or electrophilic) molecule and an electron donor (or nucleophilic) one. It involves triel, tetrel, pnictogen, chalcogen, halogen, and aerogen bonds as well as hydrogen bonds. Such interactions yield complexes in which the internuclear distance of the electrophilic and nucleophilic centers is intermediate between the sums of the covalent and van der Waals radii of these atoms.

Measurement in saliva from neurotypical adults of biomarkers pertinent to autism spectrum disorders.

Aim: Measure biomarkers pertinent to autism in saliva from humans.

Materials & Methods: At 7:30 PM (reading instructions) and 8:30 PM (hearing instructions), neurotypical adults (6 M, 6 F) each spat into tubes containing protease inhibitors. Cells were counted, samples aliquoted, frozen and thawed.

Hydrogen bonding and delocalization in the ELF analysis approach.

Delocalization of the electron density in the proton donor fragment has been studied for 21 complexes, A-HB (A = F, Cl; B = Ne, Ar, CO, N, FH, ClH, HO, PH, NH, Cl, F, covering the whole range of hydrogen bond strength. The proton donor and proton acceptor fragments are defined by a minimum variance principle achieved by the ELF partition. It is shown that the variance of the proton donor population as well as the charge transfer between the fragments calculated from the ELF partition is always smaller than that evaluated within the QTAIM framework.

Theoretical aspects of autism: biomarkers--a review.

Autism is dramatically increasing in incidence and is now considered an epidemic. There are no objective means to diagnose the disorder. Diagnosis is made subjectively, based on the perceived behavior of the subject.

Theoretical aspects of autism: causes--a review.

Autism, a member of the pervasive developmental disorders (PDDs), has been increasing dramatically since its description by Leo Kanner in 1943. First estimated to occur in 4 to 5 per 10,000 children, the incidence of autism is now 1 per 110 in the United States, and 1 per 64 in the United Kingdom, with similar incidences throughout the world. Searching information from 1943 to the present in PubMed and Ovid Medline databases, this review summarizes results that correlate the timing of changes in incidence with environmental changes.