Decrease In Peak Area Research Articles

Application of differential scanning calorimetry to cure optimization and quality control of a vinyl ester resin

AbstractTo optimize cure time for a given resin, the relationship between time, temperature, and degree of cure must be established. Using an epoxy‐based vinyl ester as an example, these relationships were determined with the use of differential scanning calorimetry (DSC). DSC curves can indicate the glass transition temperation (Tg) and the residual cure exotyherm (RCE) peak of a plastic of composite smaple. With increasing degree of cure, (Tg) increases, and the RCE peak area decreases. The data confirms a model showing that various timetemperature combinations can lead to the same degree of cure. Graphic representations of the relationships between time, temperature, and degree pf cure presented, which include degration regions (here, both Tg and shear strength are lowered). Graphs may be used for optimizing production cure conditions and for setting quality control criteria. This method should be applicable to most thermoset resins.

Some aspects of the structure-properties relationships associated with haze in SOS

Silicon on sapphire wafers having visual haze ratings from 1–8 have been characterized by using a variety of techniques, including X-ray rocking curve analysis, X-ray orientation measurements, lattice parameter determination, resistivity measurements and Hall mobility measurements. The results indicate that: (1) Considerable X-ray line broadening occurs above a visual haze level of 3. (2) (100) X-ray peak area decreases rapidly above visual haze level of 3. (3) A change from a predominantly [100] silicon orientation to a mixed {100} and {110} orientation occurs concomitantly with the {100} peak area decrease above a visual haze level of 3. (4) The lattice parameter is not dependent upon haze level. (5) Resistivity increases of 2–3 orders of magnitude occur above a visual haze level of 3. (6) Point-to-point resistivity variations occur which are dependent upon deposition temperature. (7) Hall mobility is related to the visual haze level. (8) UV reflectivity measurements can be correlated with visual haze ratings but are capable of discriminating haze sub-classes within the visual haze 1 range. These techniques yield a self-consistent set of measurements which show that both microstructure and impurity levels (autodoping) can be correlated with the visual haze rating.

Effect of surface plasmon oscillations on Auger electron emission

The integrated areas of the Al L 23VV and O KL 23L 23 Auger peaks and the Al surface plasmon energy ħω S are reported for the Al(001) surface as a function of exposure to O in the exposure range 0–114 L(1 L=1langmuir=10 −6Torr sec). It is shown that for exposures below a critical value of 15 L, ħω S is constant within experimental error while the O Auger peak area increases linearly. For exposures above 15 L, ħω S decreases linearly from 10.5 eV to 8.5 eV and the O Auger peak area undergoes relatively slow linear increases correspondingly. The Al Auger peak area decreases by 30% per 1 eV decrease of ħω S. The results are discussed with reference to theory relating Auger transition intensities to the spectral density function.

Studies on the elastase-serum protein interaction II. On the digestion of human [formula omitted], an elastase inhibitor, by elastase

Previous experiments with elastase (pancreatopeptidase E, EC 3.4.4.7) whole serum mixtures had shown that α 2- macroglobulin was an elastase inhibitor. These experiments also had shown that the α 2- macroglobulin-elastase complex was unstable, suggesting the possibility that the inhibitor ( α 2- macroglobulin ) was digested by the enzyme. α 2- Macroglobulin was isolated from human whole serum by fractional precipitation with (NH 4) 2SO 4 followed by gel filtration and anion-exchange chromatography. An alternate procedure used preparative ultracentrifugation preceding the gel filtration stage. 1.08 moles of purified α 2- macroglobulin was capable of binding 1 mole of elastase. The dissociation constant for the α 2- macroglobulin-elastase complex was K = 1.3 · 10 −8 . Analysis of time-course elastase-α 2-macroglobulin mixtures in the analytical ultracentrifuge revealed that 28% of the α 2- macroglobulin was digested in 20 h at 37° (decrease in peak area) and 44% at the end of 47 h. Analysis of the 47-h digest by double diffusion in agar gel showed, in addition to a main precipitation line, two additional arcs of precipitate representative of α 2- macroglobulin fragments. Judging from the diffusion rates in agar gel and shape of the precipitin lines these fragments possess molecular weights of the order of 50 000 and 200 000. Analysis of the 47-h digest by zone electrophoresis followed by overlaying with substrate showed the fragments produced to be associated with active enzyme. These results confirm the earlier suggestion that α 2- macroglobulin is digested by elastase and offer an explanation for the possible existence of free elastase in peripheral blood or tissue.