Myelomatous involvement of the maxilla is an exceptionally rare occur­ rence, and the presentation of the lesion as an expansile jaw bone tumour has not been reported. 2 cases, one with a maxillary lesion, the other with a mandibular lesion are presented, both of which illustrate gross bone expansions. Additionally, I case presented with a rare biclonal TgG kappa and IgG lambda light chain secreting myeloma. Relevant clinical , immunological, histological , biochemical and histochemical features are presented and discussed, and suggestions pertaining to surgical. management made. E. J. Raubenheimer', G. E. Lello', J. Dauth" M. S. Fayman , N. Dvornak and J. C. SenekaP 'Department of Oral Pathology; 'Department of Maxillofacial and Oral Surgery; 'Department of Chemical Pathology, Medical University of Southern Africa , Medunsa

Tracing the source of origin of illegal ivory will contribute to the identification of poorly managed game parks and facilitate steps taken to prevent the African elephant from becoming extinct. This study was aimed at establishing a database on the composition of ivory obtained from elephant sanctuary areas in Southern Africa. Fragments of elephant ivory from seven geographically distinct areas in South Africa, Namibia and Botswana were analysed for inorganic and organic content. A total of 20 elements was detected in the inorganic fraction of ivory, some in concentrations as low as 0.25 μg/g. The concentrations of calcium, phosphate, magnesium, fluoride, cobalt and zinc showed statistically significant differences (p<0.007) between ivory obtained from different regions. Analyses of the organic fraction identified 17 amino acids. Ivory from arid regions showed significantly lower proline plus hydroxyproline content and under-hydroxylation of lysine residues. This study indicates that chemical analyses of ivory could be beneficial in tracing the source of illegal ivory.

Trifunctional methyltrimethoxysilane and bifunctional dimethyldimethoxysilane monomers were cocondensed in water in the presence of surfactant. Strictly spherical micronetworks of narrow size distribution were obtained for particle sizes 10 nm < R < 30 nm. By special ''endcapping'' reactions all reactive SiOH groups were removed quantitatively, and the resulting micronetworks become soluble in common organic solvents like toluene, THF, or chloroform. For contents of trifunctional monomer larger than 50 mol % the particles do not swell irrespective of the choice of the solvent, whereas for lower mole fractions of trimethoxysilane an increasing swelling ratio is observed. Below 2.5 mol % trifunctional monomer the reaction within a microparticle remains subcritical and nonspherical, branched molecules are obtained. Subsequent addition of the bi- and trifunctional units leads to a micronetwork topology with different physical properties as compared to the simultaneously cocondensed one at identical overall particle composition. For instance, at 57 mol % trifunctional monomer content the ''homogeneously'' cross-linked microgel exhibits no glass transition before decomposition whereas the core-shell particle with linear chains in the core shows a weak glass transition at T-g = -107 degrees C.

Extremely small monodisperse micronetworks have potential applications as molecular containers or reaction vessels. The advantages of the sol‐gel synthesis reported here, involving endcapping with Si‐O‐SiR3 groups, are pointed out and the characterization of the resulting spherical particles (radius between 5 nm and 20 nm), see Figure, is described. The variety of functional groups and the high density of potential reaction sites are stressed.magnified image

Even UV-curing and electron beam (EB) curing systems must contain suitable additives before many of the properties required by customers may be obtained. A fundamental aspect of formulating is good compatibility between the additives and the other components in the system. A new generation of polydimethylsiloxanes has been developed that is not only compatible but also reduces foaming tendency and slip resistance and improves surface tension.

Graft copolymers with poly(organosiloxane) backbone and thermoplastic side chains have been synthesized via the “grafting from” method based on azo- and triazene modified poly(organosiloxane)s. Initiation of free radical polymerization is possible from the polymeric azo and triazene initiators after thermal decomposition of the labile functions in solution. The graft products have been characterized by NMR, GPC, and DSC. Stable, free standing films can be cast from the graft copolymers.

The photolytic decomposition of tetrakis(1-phenyl-3-hexyl-triazenido)-platinum(IV) is studied in a variety of media, and found to proceed according to simple first order kinetics. Two excimer laser wavelengths, an excimer-laser pumped dye laser, and a broadband mercury lamp are used for excitation. As referred to the incident power, selective irradiation near the complex-specific absorption maximum is found to be most efficient for inducing the photolytic decomposition. A different influence of degassing and oxygen saturation is observed for tetrahydrofurane and for technical siloxane solvents. To elucidate the origins of the observed behaviour, decomposition products of the complex, and products of hydrosilylation reactions catalyzed by this compound, are identified by GC/MS analysis.

The triazenols 4-R(1)-C6H4-N=N-N(OH)-R(2) (1), oxidized with t-BuO(2)(.) radicals, produced nitroxide radicals R(1)-C6H4-N(O-.)-N=N(R(2))O-+(-) (5). The suggested radical structure was confirmed by N-15-labeling. The reaction of triazenols 1 with PbO2 proceeded under N-2 elimination, in which case nitroxides R(1)-C6H4-N(R(2))-O-. (2) were observed as the final radical products. The intermediate R(1)-C6H4. radicals were identified by spin-trapping.

Triazenes p-R1–C6H4–NN–NR2R3(R1= H, butyl, CH3O, CN and NO2, R2= CH3, cyclohexyl, butyl or longer chains, R3= H, OH) are irreversibly cathodically reduced at –1.5 to –2.7 V (vs. saturated calomel electrode) and oxidised from 0.8 to 1.7 V. The reduction peak potentials became more negative and the first oxidation peak potentials less positive if R3 was OH. Using spin-trapping, radicals p-R1–C6H4˙ and ˙R2 were identified as fragmentation products in the electrolytic and peroxy-initiated decomposition of triazenes. Radicals p–R1C6H4–NO˙–R2, representing the oxidised cage products after N2 elimination, were observed in the oxidation of triazenes with peroxy acid. An NO2-centred radical anion was found in the cathodic reduction of a Pt complex with R1= NO2. The above specified decomposition route of triazenes is modified if these are coordinated in Pt complexes. The formation of radicals is discussed assuming two tautomeric forms of triazenes.

Siloxanes with vinyl ether groups are prepared by hydrosilylation reaction of dihydrosiloxanes with divinyl ethers in excess. Different stoichiometry, produces linear copolymers of different viscosities and double bond concentrations always with an active vinyl ether group at each chain end. Polymerisations triggered by UV light were done with mixtures of these compounds and a series of onium salts. Very fast cure is observed even with low doses at 290 nm. V.E. silicones are found to cure essentially quantitative. The comparison with other highly reactive cationic monomers revealed that compounds are among the fastest curing prepolymers in cationic chemistry.

Polycondensation of methyltrimethoxysilane in the presence of the surfactant benzethonium chloride yields strictly spherical organosilicon micronetworks of controlled size in the range of 3 nm less than or equal to R less than or equal to 15 nm with R the particle radius. After a short induction period the size of the particle increases linearly with the cube root of added monomer volume which proves the number of growing nuclei to be constant with time or conversion, whereas the mechanism controlling the number of growing nuclei remains unclear. In many respects the polycondensation resembles a condensation in mu-emulsion although the surface are per surfactant molecule (headgroup area) is shown to decrease with decreasing particle size, a fact which is not yet understood. The particle density in solution is only about one-third of the dry particle density which means that the mu-network is considerably swollen in solution.

The first homoleptic tetrakis(arylalkyltriazenido) derivative of platinum, [C6H5NNN(CH2)5CH3]4Pt (3), has been prepared by reacting platinumtetrachloride with 1-phenyl-3-n-hexyltriazene and n-butyllithium in THF. The readily soluble, yellow complex, stable towards air and water, has been characterized by single cristal x-ray cristallography and Pt-195 NMR spectroscopy. Compound 3 crystallizes in the triclinic space group P1BAR (a = 1090.3(3) pm, b = 1081.1(2) pm, c = 1174.4(2) pm, alpha = 93.86(1)-degrees, beta = 108.07(2)-degrees, gamma = 99.00(2), V = 1.289(1) nm3, Z = 1 and R/R(w) = 0.038/0.035). The thermo- and photochemical decomposition of the complex was investigated by DSC- and UV-measurements.

The concentrations of sodium, potassium, chloride, urea, creatinine, uric acid, total protein, albumin, inorganic phosphorous, calcium, magnesium, cholesterol, triglyceride, glucose, aspartate and alanine transaminases (AST and ALT), creatine kinase (CK), lactic acid dehydrogenase (LD), gamma-glutamyltransferase (GGT), alkaline phosphatase (ALP) and total bilirubin in the serum of a captive population of the mountain tortoise (Geochelone pardalis) (n = 13) were determined. Results varied considerably, particularly for most enzymes such as AST (11-113 U/l,ALT (1-72 U/l), CK (12-242 U/l), LD (147-2641 U/l) and ALP (56-168 U/l).

The synthesis of new, unsymmetrically functionalized azo compounds and their incorporation into polymers is described. Their photochemical decomposition and thermal stability was studied by UV spectroscopy and differential scanning calorimetry (DSC), respectively. Chemical degradation was followed by viscosity measurements.

Photosensitive microcapsules, which are thermally quite stable, are formed via interfacial polycondensation in which one of the shell-forming reactants contains an azo function.An azo monomer, containing alpha,omega-carboxylic diacid dichloride was reacted with a trifunctional aliphatic amine on the oil-water interface resulting in a shell-forming crosslinked polyamide. The size of the resulting photosensitive microcapsules was determined. It could be shown that these microcapsules can be opened by means of UV-light.