Production of 99Mo and 64Cu in a mixed field of photons and neutrons in a clinical electron linear accelerator

Journal of Radioanalytical and Nuclear Chemistry - The medical isotopes 99Mo and 64Cu were produced via the dual routes of 100Mo(γ,n)99Mo + 98Mo(n,γ)99Mo and 65Cu(γ,n)...     

Polymerization of styrene with the VOCL3–AlEt2Br catalyst system

The rate of polymerization with the VOCl₃–AlEt₂Br catalyst system at 30°C. in n-hexane reached a maximum at an Al/V molar ratio of 1.5. At this ratio, the rate of polymerization was first-order with respect to catalyst and second-order with respect to monomer concentrations. The apparent activation energy calculated was 6.4 kcal./mole. Diethylzine was found to act as a chain transfer agent. However, the molecular weights of polymers obtained were low. The possibility of bromide-containing catalyst sites acting in the termination reaction has been investigated. The average valence of vanadium is discussed in relation to molecular weights.     

Photocrosslinking and thermal behavior of the polyesters containing conjugated diacetylenes

A series of polyesters containing conjugated diacetylenic groups in the polymer backbone were synthesized by interfacial condensation of 3,5-hexadiyne-1,6-diol and diacid chlorides of succinic, glutaric, adipic, azealic, sebacic, terephthalic, and isophthalic acids. The polyesters were characterized by their infrared and ultraviolet absorption spectra, elemental analysis, and viscosity measurements. Powder x-ray patterns indicated high degress of crystallinity. The polyesters were found to be highly photoreactive. The relative photoreactivities of the polyester films were determined by the adhesion method. Only small differences in the reactivity have been observed despite structural changes in the R group in the polymer backbone. Differential thermal analysis behavior of all polymers in the temperature range ambient to 300°C and isothermal behavior of HGI at two different temperatures have been studied.     

Stability and recovery ofPenicillium funiculosum cellulase under use conditions

The stability ofPenicillium funiculosum cellulase has been investigated under the conditions used for cellulose hydrolysis. Fifty five percent of filter paper activity (FPA) was inactivated on incubation at 50°C for 24 h, whereas there was no loss in endoglucanase and β-glucosidase activity. The addition of 2% polyethylene glycol (PEG) during incubation stabilized the FPA. The influence of pH during fermentation on the thermal stability of the enzyme is discussed. The recovery of enzymes after hydrolysis of bagasse at 50°C was between 8 and 14%. Under the optimal conditions of elution, the recovery of enzyme was 35% (1). Increasing the enzyme to the substrate ratio fivefold and presence of PEG during hydrolysis resulted in 80, 83, and 95% recovery of β-glucosidase, FPA, and endoglucanase activity, respectively. Index Entries: Stability; recovery of cellulase P.funiculosum.     

Quantum state reconstruction for rigid rotors

We describe a quantum state reconstruction scheme for dipolar rigid rotors based on determination of the expectation value of the molecular orientation. A key feature is the use of half-cycle pulses to excite the rotor prior to the orientation measurement. The set of expectation values obtained by varying the intensity and polarization of the laser and the time interval between excitation and measurement can be inverted directly to yield the rotor density operator. When the density operator corresponds to the admixture of relatively few rotor states, our procedure successfully reconstructs both pure and mixed states.