5\u27-Nucleotidase and Thrombin-Like Activities of Selected Crotalid Venoms

Thrombin-like activities were not observed inCrotalus basiliscus, C. molossus and C. scutulatus scutulatus crude venoms. 5\u27-Nucleotidase specific activities of 0.863, 0.273 and 5.520 units/mg of crude venom protein were observed inC. basiliscus, C. molossus and C. s. scutulatus venoms, respectively. Concanavalin ASepharose 4 B (Con A)affinitychromatography yielded two fractions from each of the crude venoms. Ineach instance, both fractions exhibited 5\u27-nucleotidase activities and the Con A-binding proteins had higher activities than the Con A-nonbinding proteins. 5\u27-Nucleotidase activities inthe DEAESephadex A-50 chromatographic fractions were localized in the first elution fraction and the last fraction(s) to elute. EDTAhad no effect on the 5\u27-nucleotidase activities ofthe crude venoms

5\u27-Nucleotidase and Thrombin-Like Activities of Selected Crotalid Venoms

Thrombin-like activities were not observed inCrotalus basiliscus, C. molossus and C. scutulatus scutulatus crude venoms. 5\u27-Nucleotidase specific activities of 0.863, 0.273 and 5.520 units/mg of crude venom protein were observed inC. basiliscus, C. molossus and C. s. scutulatus venoms, respectively. Concanavalin ASepharose 4 B (Con A)affinitychromatography yielded two fractions from each of the crude venoms. Ineach instance, both fractions exhibited 5\u27-nucleotidase activities and the Con A-binding proteins had higher activities than the Con A-nonbinding proteins. 5\u27-Nucleotidase activities inthe DEAESephadex A-50 chromatographic fractions were localized in the first elution fraction and the last fraction(s) to elute. EDTAhad no effect on the 5\u27-nucleotidase activities ofthe crude venoms

An Absolute Measurement of Neutron Flux Using Calorimetry

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Measurement of the Neutron Lifetime by Counting Trapped Protons

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Measurement of the Neutron Lifetime by Counting Trapped Protons

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

A gamma- and X-ray detector for cryogenic, high magnetic field applications

As part of an experiment to measure the spectrum of photons emitted in beta-decay of the free neutron, we developed and operated a detector consisting of 12 bismuth germanate (BGO) crystals coupled to avalanche photodiodes (APDs). The detector was operated near liquid nitrogen temperature in the bore of a superconducting magnet and registered photons with energies from 5 keV to 1000 keV. To enlarge the detection range, we also directly detected soft X-rays with energies between 0.2 keV and 20 keV with three large area APDs. The construction and operation of the detector is presented, as well as information on operation of APDs at cryogenic temperatures

Radiative β decay of the free neutron

The theory of quantum electrodynamics predicts that the β decay of the neutron into a proton, electron, and antineutrino is accompanied by a continuous spectrum of emitted photons described as inner bremsstrahlung. While this phenomenon has been observed in nuclear β decay and electron-capture decay for many years, it has only been recently observed in free-neutron decay. We present a detailed discussion of an experiment in which the radiative decay mode of the free neutron was observed. In this experiment, the branching ratio for this rare decay was determined by recording photons that were correlated with both the electron and proton emitted in neutron decay. We determined the branching ratio for photons with energy between 15 and 340 keV to be (3.09±0.32)×10-3 (68% level of confidence), where the uncertainty is dominated by systematic effects. This value for the branching ratio is consistent with theoretical predictions. The characteristic energy spectrum of the radiated photons, which differs from the uncorrelated background spectrum, is also consistent with the theoretical spectrum

From Lurker to Active Participant

The original publication is available from www.springerlink.com. Sloep, P. B., & Kester, L. (2009). From Lurker to Active Participant. In R. Koper (Ed)., Learning Network Services for Professional Development (pp. 17-26). Berlin, Germany: Springer Verlag.In this chapter we will specifically go into the question of how prospective Learning Network users may be convinced of these benefits, for that is likely to be the necessary condition for their active participation in any Learning Network. Their question would be ‘Why should I participate?’, this chapter inventories an-swers to that question, which are then translated into a few guidelines for those contemplating to set up a particular, topic-bound Learning Network. Two kinds of answer are distinguished. Proximate answers, which affect the decision to partici-pate here and now; and ultimate answers, which motivate participation, but only in the long run, after the decision to participate has already been taken. Both are im-portant, the former to persuade people to participate, the latter to persuade people to keep participating. Before going into them, we’ll introduce a concrete example to add some realism to the discussion.The work on this publication has been sponsored in part by the TENCompetence Integrated Project that is funded by the European Commission's 6th Framework Programme, priority IST/Technology Enhanced Learning. Contract 027087 [http://www.tencompetence.org

Production of Medical Radioisotopes with High Specific Activity in Photonuclear Reactions with γ\gamma Beams of High Intensity and Large Brilliance

We study the production of radioisotopes for nuclear medicine in $(\gamma,x{\rm n}+y{\rm p})$ photonuclear reactions or ($\gamma,\gamma'$) photoexcitation reactions with high flux [($10^{13}-10^{15}$)$\gamma$/s], small diameter $\sim (100 \, \mu$m$)^2$ and small band width ($\Delta E/E \approx 10^{-3}-10^{-4}$) $\gamma$ beams produced by Compton back-scattering of laser light from relativistic brilliant electron beams. We compare them to (ion,$x$n$+ y$p) reactions with (ion=p,d,$\alpha$) from particle accelerators like cyclotrons and (n,$\gamma$) or (n,f) reactions from nuclear reactors. For photonuclear reactions with a narrow $\gamma$ beam the energy deposition in the target can be managed by using a stack of thin target foils or wires, hence avoiding direct stopping of the Compton and pair electrons (positrons). $(\gamma,\gamma')$ isomer production via specially selected $\gamma$ cascades allows to produce high specific activity in multiple excitations, where no back-pumping of the isomer to the ground state occurs. We discuss in detail many specific radioisotopes for diagnostics and therapy applications. Photonuclear reactions with $\gamma$ beams allow to produce certain radioisotopes, e.g. $^{47}$Sc, $^{44}$Ti, $^{67}$Cu, $^{103}$Pd, $^{117m}$Sn, $^{169}$Er, $^{195m}$Pt or $^{225}$Ac, with higher specific activity and/or more economically than with classical methods. This will open the way for completely new clinical applications of radioisotopes. For example $^{195m}$Pt could be used to verify the patient's response to chemotherapy with platinum compounds before a complete treatment is performed. Also innovative isotopes like $^{47}$Sc, $^{67}$Cu and $^{225}$Ac could be produced for the first time in sufficient quantities for large-scale application in targeted radionuclide therapy.Comment: submitted to Appl. Phys.