An ion chromatographic method was developed which is able to separate five unsubstituted and hydroxy C4 dicarboxylic acids, succinic, malic, tartaric, maleic and fumaric acid, besides the other unsubstituted C2-C5 dicarboxylic acids, oxalic, malonic and glutaric acids, as well as inorganic ions in samples extracted from atmospheric particulate matter. By the application of this method it was fo...

Z. Naturforsch. 53 b, 788-791 (1998); received May 25, 1998 Carnitine, Tartrate, Hydrogen Bonds L-Carnitine forms a salt-like 2:1 adduct with L-tartaric acid which crystallizes in the orthorhombic space group P212121 with Z = 4 formula units in the unit cell. The lattice is composed of an L-tartrate dianion and two crystallographically independent L-carnitinium cations. The two cations show onl...

The ortho to para conversion of water ion, H2O(+), due to the interaction between the magnetic moments of the unpaired electron and protons has been theoretically studied to calculate the spontaneous emission lifetime between the ortho- and para-levels. The electron spin-nuclear spin interaction term, Tab(SaΔIb + SbΔIa) mixes ortho (I = 1) and para (I = 0) levels to cause the "forbidden" ortho ...

The first regioselective oxidative coupling of 2-hydroxycarbazoles is described. With a vanadium catalyst and oxygen as the terminal oxidant, dimers with an ortho-ortho' coupling pattern were obtained with high selectivity. Further oxidation led to ortho'-ortho' coupling to generate a tetramer, which provided insight that the atropisomerization barriers of the unsymmetrical biaryl bonds are muc...

introduction superficial x-ray therapy is one of the most important treatment methods in radiotherapy especially in the treatment of superficial skin lesions (up to 300 kvp). quality of the x-ray beam that can be expressed by half-value layer (hvl), are important indices for this type of treatment effective energy of photon and homogeneity coefficient (hc). materials and methods the hc of the s...

Phase selective, ultrahigh loading of nanoparticles into target domains of block copolymer composites was achieved by blending the block copolymer hosts with small molecule additives that exhibit strong interactions with one of the polymer chain segments and with the nanoparticle ligands via hydrogen bonding. The addition of D-tartaric acid to poly(ethylene oxide-block-tert-butyl acrylate) (PEO...

Background and Aim: This study aimed to evaluate the effect of repeated bonding by self-etching primers (SEPs) and a conventional phosphoric acid-etchant on shear bond strength (SBS), adhesive remnant index (ARI), and enamel morphology at different debonding time points. Materials and Methods: In this experimental study, 120 premolars were randomly divided into six groups of 20. In the first t...

PURPOSE Myopia is a common ocular disorder, and progression of myopia in children is of increasing concern. Modern overnight orthokeratology (ortho-k) is effective for myopic reduction and has been claimed to be effective in slowing the progression of myopia (myopic control) in children, although scientific evidence for this has been lacking. This 2 year pilot study was conducted to determine w...

Tartaric acid is one of the most prominent naturally occurring chiral compounds. Whereas its application in the production of chiral ligands for metal-catalysed reactions has been exhaustively investigated, its potential to provide new organocatalysts has been less extensively explored. Nevertheless, some impressive results, such as the use of TADDOLs as chiral H-bonding catalysts or of tartrat...