Activation spectra, measurement

While the control resins were deep red in color due to the presence of soluble porphyrin complexes, the methacrylate resins obtained after removal of the polyethylene-supported catalysts varied from light yellow to nearly water-white (APHA < 25). UV-Vis spectrophotometric analysis of the yellow resins indicated an absorption signal for the cobalt porphyrin complex Soret band (wavelength of cobalt(ll) porphyrin species appears at -415 nm free porphyrin ligand is formd at -423 tun). Resin samples that visttally appear as water-white show little or no porphyrin species present in the spectrum. Measured catalyst activity and PDl of the polyethylene-supported porphyrin complexes are in the expected range for soluble porphyrin CCT catalysts (PDl = M /Mn - 1.2- 2.0)." The screening resrrlts clearly... 

Sader HS, Fedler KA, Rennie RP, Stevens S, Jones RN. (2004) Omiganan pentahydrochloride (MBI 226), a topical 12-amino-acid cationic peptide Spectrum of antimicrobial activity and measurements of bactericidal activity. Antimicrob Agents Chemother 48 3112-3118. 

Figure 1 shows the activation spectrum of polystyrene measured by Hirt and co-workers (8). It represents the yellowing, as measured by the increase in absorbance at 4000 A., caused by the various wavelengths of ultraviolet radiation between 2800 and 4000 A. The ultraviolet source used for these measurements was a xenon arc equipped with a borosilicate... 

Figure I. Activation spectrum of polystyrene measured by Hirt et al. (8)...

After purification the enzymes were precipitated by 80% ammonium sulphate in 250mM potassium phosphate, (containing O.SmM EDTA) pH 7.6 and stored at 4°C in an approximately 5-fold excess, of FAD. Prior to use, the enzyme was dissolved in 250mM KPi, 0.3 mM EDTA, pH 7.6, and run through a Sephadex G-25 column to remove the ammonium sulphate and excess FAD. The enzyme concentration was measured from the visible spectrum, taking 443 = 14,8001.mor. cm l Total protein was measured by the Bradford microassay and enzyme activity was measured by the ferricenium assay. ... 

Same material but containing 0.1% of a photostabilizer (Cyasorb UV 3346, American Cyanamid Co.) was also studied in a similar experiment designed to obtain a direct activation spectrum of the material [133]. After 1400 h exposure in an Atlas Ci 65 weatherometer, the samples showed measurable changes in both elongation at break as well as the tensile strength. Maximum effectiveness was found at A = 335-355 nm. 

A new coupled neutron-gamma multigroup library for 26 nuclides has been generated, based on Evaluated Nuclear Data File ENDF/B-IV for shielding calculations and validated. Activation cross sections for a number of materials used as activation foils for neutron flux and spectrum measurements have been prepared. 

Neutron flux and neutron spectrum measurements require an assortment of neutron activation foils and threshold detectors (e.g., Au, In, Cd, Al) as well as counting facilities such as gas flow proportional counters, Nal or HPGe detectors to any level of sophistication desired. 

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