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Presents a study which measured the hole-drift-mobility of molecularly doped polymer diethylaminobenzaldehyde-diphenyl hydrazone in polycarbonate. Experimental details; Results and discussion; Conclusion.

Background: Single-particle and collective modes of nuclear excitation compete in the isotopes of the elements 30Zn, 32Ge, 34Se, 36Kr, and 38Sr. Purpose: To study the factors which determine the onset of collectivity in this region. Methods: Data obtained from National Nuclear Data Center compilations supplemented by recent measurements of excitation energies and B(E2) reduced transition probabilities between the low-lying states in these elements were examined. The data were analyzed as a function of the neutron number N as well as the parameter P = NpNn/(Np + Nn) related to the number of valence protons and neutrons, Np and Nn, in the 28 ≤ Z,N ≤ 50 shell. Results: The systematics of the data show variations ranging from mostly single-particle to collective excitations. Conclusions: Collectivity sets in when the number of both protons and neutrons lie near the middle of the shell 30 ≤ Z,N ≤ 50. Backbends appear in the data showing that particles and holes in the major shell behave differently. The 22+ states exhibit single particle behavior. The transition probabilities of the 22+ states in the Kr isotopes differ significantly from the systematics. [ABSTRACT FROM AUTHOR]

Using a pin-on-disc sliding-wear test apparatus, the wear behavior of a typical composite restorative vs. styli fashioned from human enamel, sintered alumina, and magnesium fluoride was examined. The rates of restorative wear were found to be identical, within the experimental error of the measurements, for tests using either human enamel pins or styli fabricated from sintered alumina. Moreover, these two pin materials generated morphologically similar wear-tracks in the restorative disc. Thus, styli of sintered alumina produce restorative wear that is both qualitatively and quantitatively analogous to that observed in tests using human enamel pins. [ABSTRACT FROM AUTHOR]

The wear behavior of a composite restorative in sliding contact with a stylus fashioned from human enamel has been investigated as a function of the effective stiffness of the stylus-restorative contact. The results demonstrate that: (1) the stiffness parameter affects wear surface morphology of both the composite and the enamel; and (2) a decrease in stiffness produces a larger variance in the rate of wear of a composite, but this factor has no significant effect on the average wear-rate for the material and test conditions explored. [ABSTRACT FROM AUTHOR]

The sliding-wear behavior of a number of commercially available microfilled and light-cured composite restoratives has been investigated and compared with the wear characteristics of conventional composites. The surface profiles of the composite restoratives, both pre- and post-test, have also been examined in order to study material attrition processes. The results indicate that: (1) microfilled composites are significantly more resistant to sliding wear than are restoratives containing conventionally-sized filler particles; (2) light-cured, microfilled composites exhibit a lower rate of sliding wear than do self-curing, microfilled restoratives; and (3) the wear process leads to an increase in surface roughness for all materials tested, but microfilled materials display lower surface roughness values, both before and after sliding-wear tests, than do restoratives containing conventional-sized filler particles. [ABSTRACT FROM AUTHOR]

Background: The 8838Sr and 9040JZr nuclei have been utilized as closed cores for large-scale shell-model calculations in the 28 ≥ Z ≥S 50 region around the N = 50 shell. Measurements of magnetic moments for nuclei in this region would provide microscopic information about the use of 88Sr and 90Zr as stable closed-core nuclei. While the g factors of the T+1 states in the stable Sr isotopes have been previously measured, experimental g factors for the radioactive 82,90Sr have not been obtained to date. Purpose: The purpose was to measure the g factors of the 2+1 and 4+1, states in the unstable 82Sr and 90Sr nuclei in order to extend the systematics along the Sr isotopic chain. A comparison of the structure of the N = 52 isotopes 90Sr and 92Zr will shed light on the relative robustness of proton subshell closures at Z = 38 and Z = 40. Methods: The pickup reaction of α particles in inverse kinematics together with the transient field technique were applied to beams of 78Kr and 86Kr at the Cyclotron Institute of Texas A&M University. Results: The values g(82Sr;2+1) = +0.44(19), g(82Sr;4+1) = +0.53(39), g(90Sr;2+1) = -0.12(11), and g i S r f ) = -0.02(17) were measured for the first time. Simultaneously, the g factors of the low-lying states in the Coulomb-excited beam projectiles were remeasured. The g(4+1) = +1.03(14) in 86Kr was also measured for the first time. Conclusions: For 82Sr both g factors are in agreement with the collective value Z/A expected for nuclei in the middle of a major shell. The g factors in 90Sr are negative but smaller than in the isotone 92Zr. The results also indicate that 88Sr is a proton-soft core nucleus and perhaps even softer than 90Zr. [ABSTRACT FROM AUTHOR]

The influence of several experimental parameters on the sliding-wear behavior of a composite restorative has been examined. The results demonstrate that: 1) Changes in surface finish and sliding velocity have little effect on the moderate wear-rate observed at nominal levels of stress, and 2) increased contact stress can profoundly alter wear mechanisms and produce marked surface failure at levels well within the range associated with human mastication.

Ten strains of Byssochlamys fulva and three strains of B. nivea were cultured in a laboratory medium and tested for their ability to produce patulin. Two strains of B. fulva and all three strains of B. nivea produced the mycotoxin. One strain of B. fulva produced patulin in 11 of 13 processed fruit juices, with greatest amounts being produced in blueberry, red raspberry, and boysenberry juices, whereas no patulin was detected in prune or tomato juices. Grown in Concord grape juice at 18, 25, 30, and 38 degrees C, this strain produced the highest patulin concentration at 18 degrees C after 25 days, whereas biomass production was greatest at 25 and 30 degrees C after 20 and 25 days.

Polygalacturonase, biomass, and ascospore production by four strains of Byssochlamys fulva cultured in laboratory media supplemented with glucose, sucrose, or fructose was studied over a 20-day incubation period at 30 degrees C. The production of polygalacturonase was variable, but most activity was detected between 4 and 8 days in 1% sugar media at an initial pH of 4 or 5. The rate of biomass production was retarded early in the incubation period in media initially at pH 3 or 4 as compared to pH 5, but the amount of growth was about the same in media containing the test sugars after 20 days. Large numbers of ascospores were produced between 8 and 10 days in media containing 5% sugar initially at pH 5 and 4. Production of ascospores was retarded at pH 3 in media containing 5% sugar as compared to media initially at pH 5 and 4.

The influence of variation in contact stress on the sliding-water behaviour of a dispersed amalgam has been investigated. The results demonstrate that: (1) the rate of wear of the amalgam in sliding contact with pins fashioned from human enamel remains virtually constant (0.39 +/- 0.06 micrometer/h-1) throughout the range of stresses encountered in vivo; and (2) the wear process involves adhesive transfer of amalgam to the contacting face of the enamel pin during sliding.