A method has been developed whereby the degree of cyclization of a polybenzoxazole based on 3,3′-dioxy-4,4′-diaminodiphenylmethane and isophthalic acid dichloride has been estimated on the basis of an analysis of the IR spectra of model compounds and polymeric ones containing o-oxyamide and be...

A simple gas chromatographic method is described for the analysis of 3,3′-dichloro-4,4′-diaminodiphenylmethane (MOCA) in air. MOCA is quantitatively collected on a Gas-Chrom S tube and the solid sorbent is extracted with acetone. An aliquot sample of the extract is introduced directly into the...

The kinetics of polycondensation of the diglycidyl ether of diphenylol propane and 3,3′-dichloro-4,4′-diaminodiphenylmethane has been studied by GPC and pulsed NMR. It is shown that in a wide interval of depths of conversion to the point of gel formation change in the concentrations of the sta...

Oxidation of the polybenzoxazole from 3,3′-dihydroxy-4,4′-diaminodiphenylmethane and isophthalyl dichloride, occurring during heat treatment at 240–350°C has been investigated. It is shown that at 240–300°C it is mainly the aliphatic groups of the polybenzoxazole that undergo oxidation. At...

Optimum conditions were found for the synthesis of aromatic polyimides based on 3,3′-dihydroxy-4,4′-diaminodiphenylmethane and pyromellitic or 3,3′4,4′-tetracarboxydiphenyloxide dianhydrides. Benzoxazole-imide copolymers based on polyhydroxyamide and polyamide acid were obtained. The effect ...

Heterogeneous synthesis of 3,3′-dimethyl-4,4′-diaminodiphenylmethane (MDT) from o-tolylamine and formaldehyde on acidic zeolites HY, HZSM-5, Hβ and TS-1 was investigated. Hβ zeolite with strong Bronsted acidity and proper textural property demonstrated better catalytic performance than other...

Synthesis of 3,3′-dimethyl-4,4′-diaminodiphenylmethane (MDT) from o-tolylamine and formaldehyde over zeolites was investigated. Among the three tested zeolites, Hβ showed higher catalytic activity than HY and HZSM-5 for MDT synthesis. In the case of Hβ as a catalyst, the effects of feed comp...

Collision-induced dissociation (CID) of hexapeptide radical cations consisting of four alanine residues, one α-methyltryptophan and a glycine residue at the C-terminus results predominantly in bond cleavages around the sterically crowded α-methyltryptophan residue, but all generated [b5 – H]+...

Radicals produced in L-alanine-3,3,3-d3 and L-alanine-d4 by X-irradiation and their spectral change were investigated using X-band ESR. Apparently, two major radicals appeared. One is the radical formed by deamination from a protonated anion and the other is produced by the loss of an alpha hydr...

The structural and energetic properties for neutral and charged complexes of transition metal atoms and benzene molecules, TM(C6H6)m ≤ 3, TM = Fe, Co, Ni, were studied using density functional theory. Including dispersion corrections all-electron calculations were done with the BPW91–D2 and M1...

The pure rotational spectra of 1,2- and 1,3-benzene-d2 have been measured over the 8–18 GHz range with a pulsed microwave Fourier transform spectrometer. Rotational constants have been determined from the measured transition frequencies. Structural information has been obtained from the moments...

Rubrosterone, a metabolite of ecdysterols isolated from Achyranthes spp. (Amaranthaceae), has been synthesized by two routes from ecdysterone.

A metabolite of insect moulting hormone, rubrosterone was synthesized from dehydroepiandrosterone in 20 steps.

Manganese–calcium and manganese–strontium heteronuclear compounds are of considerable current interest in the context of modeling the structure of the oxygen-evolving complex (OEC) of photosystem II (PSII), an oxygen-bridged Mn4CaO5 cluster stabilized by carboxylate ligands. This review survey...

Strontium efficiently activates mouse oocytes, however, there is limited information on its use in cattle. Thus, the objective of this study was to establish a suitable protocol for activating bovine oocyte with strontium. For pronuclear development, the absence of calcium and magnesium in the a...

Publisher SummaryThis chapter discusses the decomposition of azides. The inorganic azides constitute a particularly well-defined group of relatively simple ionic reactants and the optical properties of many metal azides permit the determination of the band structures of the solids. From these, t...

Strontium (Sr) has become more attractive for orthopaedic applications as they can simultaneously stimulate bone formation and prevent bone loss. A Sr-containing bioactive bone cement (Sr-BC) has been designed to fix osteoporotic bone fracture. Sr is a trace element, so the safety of containing ...

Strontium (Sr) is known to stimulate osteogenesis, while inhibiting osteoclastogenesis, thus encouraging research on its application as a therapeutic agent for bone repair/regeneration. It has been suggested that it may possess immunomodulatory properties, which might act synergistically in bone...

ObjectivesDentin hypersensitivity often is treated by promotion of dentin tubule occlusion. In this in vitro study we evaluated nanomechanical properties and degree of tubule occlusion conferred to sound and demineralized human root dentin following treatment with a 10% (w/w) strontium acetate s...

The thermal stability of solid strontium azide is considerably reduced by pre-irradiation with γ-rays (Co60). The isothermal decomposition of the unirradiated salt is followed by measuring the pressure of gas evolved in a constant-volume system. It is characterised by a pronounced induction per...