A method for stabilising technetium-99m exametazime prepared from a commercial kit

Technetium-99m exametazime (99mTc-d,l-HMPAO), prepared by the reconstitution of the Ceretec kit, is widely used in the investigation of regional cerebral blood flow. The radiochemical purity specification of not less than 80% lipophilic complex requires that the kit is used within 30 min of reconstitution. In certain circumstances this imposes restrictions on its clinical availability. A number of approaches to extending the 30-min shelf life have been proposed and these are discussed. A method of stabilising the kit by the addition of 200 micrograms cobalt chloride hexahydrate (CoCl2 x 6H2O) in 2 ml of water is described. The addition of this solution can extend the shelf life of the reconstituted kit to at least 5 h post reconstitution.     

A theory for the diffusion of large molecules in amorphous polymers above Tg

A general theory of diffusion of large molecules in rubbery amorphous polymers is of interest for the scientific understanding and with regard to material design and process optimization. A broadly applicable model would be useful in developing controlled transport of plasticizers and other additives through polymeric substances. A diffusion model is presented which has been developed for large molecular penetrants above the T_g of the amorphous polymer allowing for required increase in redistribution of the free volume of the polymer structure, as well as the penetrant size and shape. Applicability of the model is demonstrated by comparing theoretically developed diffusion curves for DNOP and DNDP in PVC vs. their weight fractions at 82°C and 91°C. These theoretically derived plots are compared with experimental D vs. w₁ curves for these systems generated at lower temperature.     

Asymptotic stability and the method of linear bounds

If x? = Ax is asymptotically stable, it is possible to find linear bounds for g(x); so that x? = Ax + g(x) is also asymptotically stable. An explicit expression is given for functions which satisfy these bounds.     

Parentally provided alkaloid does not protect eggs ofUtetheisa ornatrix (Lepidoptera: Arctiidae) against entomopathogenic fungi

Eggs ofUtetheisa ornatrix proved equally vulnerable to fungal infection (Beauveria bassiana, Paecilomyces lilacinus) whether they contained parentally provided pyrrolizidine alkaloid (monocrotaline) or were free of such alkaloid. In in vitro tests, monocrotaline, either as free base or N-oxide, had no inhibiting effect on fungal cultures.Report No. 99 of the series Defense Mechanisms of Arthropods; No. 98 is Attygalle et al.,Experientia (in press).     

An airborne far-infrared spectrometer for astronomical observations

A Fabry-Perot spectrometer for airborne observations of astronomical spectral lines has been designed for use in the 50 to 200 μm region of the far-infrared. The spectrometer uses a fixed wavelength Fabry-Perot filter cooled to 4.2 K in conjunction with a high order scanning Fabry-Perot at room temperature. This arrangement provides high spectral resolution and also minimizes the thermal background radiation on the detector. The instrument has been successfully used to study all the presently detected fine structure lines between 50 and 120 μm.     

The effect of changes in initial reactant composition on solid-gas equilibria resulting from constant-volume,adiabatic processes

A method is given for the computation of the chemical equilibria attained by adiabatic chemical reactions in similar systems, all with the same volume and mass, as a result of changes in the initial reactant compositions. Changes in equilibrium composition and temperature are directly related to changes in the initial elemental abundances, in the form of a set of simultaneous equations. Since it is not necessary to perform complete calculations for each solution required, the solution of these equations constitutes a saving in computation. The method can be applied to solid-gas systems. The systems must be ideal or they have to obey an empirical equation of state, wherein covolume is a function of volume only.     

New polyisobutylene-based model ionomers

Mechanical properties of tri-arm polyisobutylene based ionomers have been investigated. Number average molecular weights (¯M_n's) of the polymers were varied from 8,300 to 34,000. The ionomer of lowest ¯M_n (8,300) exhibits very low extension at break (～ 150%) while the others with ¯M_n's of 11,000, 14,000 and 34,000 show very high extensions, often exceeding 1,000%, and display relatively low permanent set and low hysteresis behavior. Since the ionic bonding is located exclusively at the chain ends, end-linked pseudo networks are formed due to coulombic attractions.At higher temperatures the coulombic interactions are weakened and the networks can be compression molded (～150°C).     

Australian SKA Pathfinder: A High-Dynamic Range Wide-Field of View Survey Telescope

The Australia SKA Pathfinder (ASKAP) is a new telescope under development as a world-class high-dynamic-range wide-field-of-view survey instrument. It will utilize focal plane phased array feeds on the 36 12-m antennas that will compose the array. The large amounts of data present a huge computing challenge, and ASKAP will store data products in an archive after near real-time pipeline processing. This powerful instrument will be deployed at a new radio-quiet observatory, the Murchison Radio-astronomy Observatory in the midwest region of Western Australia, to enable sensitive surveys of the entire sky to address some of the big questions in contemporary physics. As a pathfinder for the SKA, ASKAP will demonstrate field of view enhancement and computing/processing technology as well as the operation of a large-scale radio array in a remote and radio-quiet region of Australia.