Organometallic polymers. II. Crosslinking of ferrocenylene–methylene-type polymers

Poly(ferrocenylene-methylmethylene) (PFMM) was prepared and subsequently crosslinked by the aid of either 1,1'-bis(α-hydroxyethyl)ferrocene or polyfunctional ferrocene polymers, containing reactive-CH₂OH or-CH(CH₃)OH groups. The thermal behavior of both the primary polymer and the thermoset was investigated. The solubility parameter of PFMM was determined and the degree of crosslinking was studied by solvent swelling and sol fraction measurements. Various thermosetting structural composites were prepared and subjected to mechanical testing.     

Characteristics of the 4-methylumbelliferone laser dye

The emission characteristics of the coumarin-dye 4-Methyl-umbelliferone (4-MU) are investigated by studying the low-intensity fluorescence spectra and the laser-pumped gain spectra for various solvents and pump powers. A total of five different forms were found to exist, each of which can be isolated in a proper solvent. Of the five species, I is the neutral molecule, two others (II and V) are results of ground-state reactions, while two (III and IV) are produced by excited-state reactions and do not have a stable ground state. By proper adjustment of the solvent a number of combinations of the five forms can coexist and lase together, giving rise to a variety of gain spectra and allowing the possibility of "tailoring" a desired gain curve over most of the visible spectrum. Comparison of the gain and fluorescence spectra indicates the presence of triplet or excited-state losses in some of the forms, yields comparative values of emission parameters, and reveals an acidity-dependent quenching of one of the excited-state species.     

Neuromuscular blocking effects of aminoglycoside antibiotics on fast- and slow-contracting muscles of the cat

The neuromuscular-blocking effects of neomycin, streptomycin, and gentamicin were examined in fast- and slow-twitch muscles of pentobarbital-anesthetized cats. These antibiotics were more effective in reducing indirectly stimulated contractions of the gastrocnemius muscle than of the ipsilateral soleus muscle in adult cats. Respiratory-depressant effects of these antibiotics were more closely associated temporally with effects on soleus than on gastrocnemius twitch. Neomycin was a more potent neuromuscular blocking agent in kittens greater than 7 weeks old than in kittens less than 6 weeks old. Calcium ions were more effective in antagonizing the effects of neomycin on gastrocnemius than on soleus twitch; however, neostigmine was more effective in antagonizing the effects of neomycin on soleus than on gastrocnemius twitch. These data indicate a difference in responsiveness of fast- and slow-twitch muscles (fast greater than slow) to the neuromuscular-blocking effects of aminoglycoside antibiotics, and suggest that this may be related to a difference in the predominance of pre- and postjunctional inhibitory actions of these agents in the 2 muscle types.     

Relationships between course of anesthesia, depth of anesthesia and acetylcholine content of the brain after urethane and pentobarbital administration in the rat

The authors describe a rare case of congenital cyst of cisterna ambiens treated surgically. Histological examination of cyst wall suggested that the cyst belonged to the group of developmental anomalies of the type of dysraphic intracranial cerebral herniae.     

Allgemeine Untersuchungsverfahren und Laboratoriumstechnik

Ohne Zusammenfassung     

Selective cation exchange resin I. Selectivity towards alkali metals

A sulphonic cation-exchange resin, containing nitro groups in the aromatic ring, was shown to have selective properties towards the heavier of the alkali metals.     

Fracture in the crossed-lamellar structure ofConus shells

Crossed-lamellar crystal architecture is the characteristic textural pattern of the calcium carbonate shell in many kinds of molluscs. By loading specimens from shells of the genusConus in various orientations in bending tests it is shown that crossed-lamellar structure is highly anisotropic. This anisotropy is to be expected from the microscopic and submicroscopic structure, particularly the substructure of the primary lamellae and their orientation to one another, and from the paths taken by cracks travelling through layers of different orientation.     

Terpolymerization studies. II. Terpolymerization of acrylonitrile,styrene, and esters of α-cyanocinnamic acid. Polymerization methods and properties

Terpolymers of acrylonitrile, styrene, and seven esters of α-cyanocinnamic acid were prepared by conventional polymerization methods up to high conversions. For emulsion polymerization systems, the rate dependence on the concentration of the emulsifier was determined. Terpolymers, made in suspension and in bulk, were used for the preparation of films and molded specimens in order to study their physical properties/chemical structure relationships.     

Die einzelnen Lebensmittel (Chemie, Technologie, Analytik)

Ohne Zusammenfassung