Assessment of bone structure and acoustic impedance in C3H and BL6 mice using high resolution scanning acoustic microscopy

Two hundred-MHz time-resolved scanning acoustic microscopy was applied for the investigation of acoustic and structural bone properties of mice from two inbred strains. Transverse sections of femur taken from 5 C57BL/6J@Ico and 5 C3H/HeJ@Ico mice were explored. Both strains had the same bone diameter, but the C3H/HeJ@Ico mice had greater cortical thickness, smaller cancellous diameter, and greater acoustic impedance values than C57BL/6J@Ico mice. The strong differences in the measured acoustic impedances among the two inbred strains indicate that the impedance is a good parameter to detect genetic variations of the skeletal phenotype in small animal models.     

Pseudorapidity distribution of charged particles in d+Au collisions at sqrt[sNN]=200 GeV

The measured pseudorapidity distribution of primary charged particles in minimum-bias d+Au collisions at sqrt[s(NN)]=200 GeV is presented for the first time. This distribution falls off less rapidly in the gold direction as compared to the deuteron direction. The average value of the charged particle pseudorapidity density at midrapidity is |eta|< or =0.6)=9.4+/-0.7(syst) and the integrated primary charged particle multiplicity in the measured region is 82+/-6(syst). Estimates of the total charged particle production, based on extrapolations outside the measured pseudorapidity region, are also presented. The pseudorapidity distribution, normalized to the number of participants in d+Au collisions, is compared to those of Au+Au and p+(-)p systems at the same energy. The d+Au distribution is also compared to the predictions of the parton saturation model, as well as microscopic models.     

Significance of the fragmentation region in ultrarelativistic heavy-ion collisions

We present measurements of the pseudorapidity distribution of primary charged particles produced in Au+Au collisions at three energies, sqrt[s(NN)]=19.6, 130, and 200 GeV, for a range of collision centrali-ties. The distribution narrows for more central collisions and excess particles are produced at high pseudorapidity in peripheral collisions. For a given centrality, however, the distributions are found to scale with energy according to the "limiting fragmentation" hypothesis. The universal fragmentation region described by this scaling grows in pseudorapidity with increasing collision energy, extending well away from the beam rapidity and covering more than half of the pseudorapidity range over which particles are produced. This approach to a universal limiting curve appears to be a dominant feature of the pseudorapidity distribution and therefore of the total particle production in these collisions.     

The role of the pyrimidine ring in the main chain of polyamic acids and polyimides

Thermoimidization kinetics of polypyromellitamic acids prepared from 2,5-bis(p-aminophenyl)pyrimidine and 4,4-diaminoterphenyl have been investigated by IR spectroscopy. It has been shown that the activation energy for the pyrimidine-containing polymer is nearly twice as low as that for the aromatic analog. This is explained by base catalysis of cyclization of the amidoacid fragments by pyrimidine rings in polymer chains. Base catalysis facilitates the process of imidization and favors the formation of polyimidic macromolecules with a lower incidence of defects. Also, the pyrimidine rings obviously catalyze the resynthesis of amidoacid fragments from the anhydride rings and amino groups formed on the destruction of the polymer chain during thermoimidization, and ensure almost complete recovery of the macromolecules with the previous bonds.For part 3, see Ref. 1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 429–432, March, 1994.The authors are grateful to T. K. Meleshko for consultations about chemical imidization.     

Thermogravimetric investigations of carbonaceous materials—Syndiotactic polystyrene systems

A system of a syndiotactic polystyrene (s-PS)-carbonaceous material, obtained as a result of syndiotactic polymerisation of styrene in the presence of carbonaceous materials of organic origin of different degree of coalification before and after their ammoxidation, was studied. The initial materials were plum stone waste, brown coal and hard coal. The interactions between the system components were studied by the method of differential scanning calorimetry (DSC). It has been found that the type of the carbonaceous material used determines the thermal effects of the phase transitions in s-PS (detected on thermograms) and the melting point of s-PS. It has been shown that on melting of the syndiotactic polystyrene in the presence of the carbonaceous materials containing a relatively large number of oxide groups, the polymer oxidation reactions occur. This effect does not occur when carbonaceous materials with preliminary ammoxidation are applied.     

Solubilities of normal alkanoic acids by the UNIFAC group contribution method

The UNIFAC group contribution method was applied to predict solubilities of C₁₀–C₂₂ normal alkanoic acids in hydrocarbons, esters, ketones, and alcohols. The results were compared with the literature experimental data. It was found that taking into account dimerization of the acids improves considerably the prediction accuracy.