background. acid etching prior to orthodontic bracket bonding may result in enamel wear or cracks following bracket removal. the manufacturer of fuji ortho lc glass-ionomer (gi) claims that it can bond brackets to wet unetched enamel. this study aimed to compare the bracket bond strength to etched and unetched enamel under dry and wet conditions. methods. in this in vitro study, 60 intact premo...

Results of an experimental study of binary recombination of para- and ortho-H(3)(+) ions with electrons are presented. Near-infrared cavity-ring-down absorption spectroscopy was used to probe the lowest rotational states of H(3)(+) ions in the temperature range of 77-200 K in an H(3)(+)-dominated afterglow plasma. By changing the para/ortho abundance ratio, we were able to obtain the binary rec...

Phthalates are widely used as plasticizers to make polymers more flexible in industrial and household products. However, lower molecular weight ortho-phthalate plasticizers have serious health effects and are restricted or banned in many countries for use in children’s products. In addition, several government agencies restrict or are investigating restricting ortho-phthalates (ortho-dialkyl ph...

Introduction In an earlier publication (2) a comparison was made of the growth regulating activites of various compounds as indicated by the elongation of sections of Avena coleoptiles. From this comparison it was seen that the substitution of various halogen atoms in the phenoxyacetic acid (POA) structure increased its effect on elongation except when both ortho positions were occupied. Also, ...

A complete theoretical model of the nuclear spin conversion in CH3F induced by intramolecular ortho-para state mixing is proposed. The model contains parameters determined from the level-crossing spectra of the CH3F spin conversion. This set of parameters includes the ortho-para decoherence rate, the magnitude of the hyperfine spin-spin interaction between the molecular nuclei and the energy ga...

A sulfoxide-directed, metal-free ortho-propargylation of aromatics and heteroaromatics exploits intermolecular delivery of a propargyl nucleophile to sulfur followed by an intramolecular relay to carbon. The operationally simple cross-coupling procedure is general, regiospecific with regard to the propargyl nucleophile, and shows complete selectivity for products of ortho-propargylation over al...

High-resolution stimulated Raman gain spectroscopy of the Q1(0) transition of para-H2 crystals with varying ortho-H2 concentrations is reported. A crystal containing 0.06% of ortho-H2 showed a single sharp Raman transition with the width of less than 7MHz. The Raman signal became broader with increasing concentration of ortho-H2 . At the concentration of 2%, the spectrum splits into a doublet. ...

The low-energy scattering of ortho positronium (Ps) by ortho Ps has been studied in a full quantum mechanical coupled-channel approach. In the singlet channel (total spin sT = 0) we find Sand P-wave resonances at 3.35 eV (width 0.02 eV) and 5.05 eV (width 0.04 eV), respectively and a binding of 0.43 eV of Ps2. The scattering length for sT = 0 is 3.95 Å and for sT = 2 is 0.83 Å. The small sT = 2...