Some focusing techniques and their application to low-angle neutron scattering

Both imaging and simple converging collimator systems can provide a focused neutron beam. Each system has been tested and appears suitable for exploitation. Imaging systems employing bent multilayer monochromators can be made simply by elastically bending a flat multilayer. The periodic spacing of the multilayer can be made to match that of the sample. The converging Soller slit provides a purely geometric means of prouducing a focused beam. Wavelength spread and distribution across the beam can be controlled separately. Soller-slit technology is further advanced than that of multilayers. The experiments sketched above demonstrate that converging or focused neutron beams suitable for low-angle scattering work can be produced with existing technology. Focusing incurs little or no loss of intensity and does not seriously distort the resolution function of a low-angel instrument. It permits a small spectrometer to make use of both advanced detector technology and large samples and thus to approach the capability of a much larger machine.     

Amyotrophic lateral sclerosis with deafness: report of a case and review of the literature

A case of chronic bulb-pontine paralysis with deafness, with early onset, coursing along nine years is reported. There seem to be histopathologic and electromyographic evidences on which is concluded to be a variant form of juvenile amyotrophic lateral sclerosis (Van Laere form).     

The relative importance of dopamine and noradrenaline receptor stimulation for the restoration of motor activity in reserpine or alpha-methyl-p-tyrosine pre-treated mice

Two animal models of Parkinsonism have been employed to investigate the role of noradrenaline in the motor effects of levodopa. Pretreatment with reserpine or alpha-methyl-p-tyrosine (AMPT) causes cerebral amine depletion and reduction of motor activity, which can be reversed by levodopa. The effect of inhibitors of noradrenaline (NA) synthesis and antagonists of NA and dopamine (DA) receptors on the action of levodopa have been studied. For comparison, the effects of such treatments on apomorphine action has been investigated. Reversal of reserpine (10 mg/kg) induced akinesia in mice by levodopa (200 mg/kg) plus the peripheral decarboxylase inhibitor MK 486 (L-alpha-methyl-dopahydrazine; 25 mg/kg) was inhibited by prior administration of phenoxybenzamine (20 mg/kg), haloperidol (1 mg/kg), pimozide (1 mg/kg) or the dopamine-beta-hydroxylase inhibitor FLA-63 (bis [4-methyl-l-homopiperazinylthiocarbonyl] disulphide; 15 or 25 mg/kg). Apomorphine (2 mg/kg) reversal of reserpine akinesia was similarly inhibited by haloperidol (1 mg/kg) and pimozide (2 mg/kg) but not by phenoxybenzamine (20 mg/kg) or FLA-63 (25 mg/kg). Apomorphine (5 mg/kg) reversal of reserpine akinesia was enhanced by simultaneous administration of the noradrenergic agonist clonidine (1 mg/kg) and this effect was not significantly altered by prior administration of FLA-63. Clonidine, however, reversed the FLA-63 induced inhibition of the levodopa effect on reserpine akinesia. Levodopa reversal of akinesia induced by AMPT (200 mg/kg) was also inhibited by FLA-63, pimozide and haloperidol. Phenoxybenzamine, however, was without effect, but produced a different pattern of behaviour. Similarly, pimozide and haloperidol blocked apomorphine reversal of AMPT induced akinesia; FLA-63 was without effect but phenoxybenzamine produced marked inhibition. The results suggest that full restoration of motor activity in reserpine or AMPT pretreated animals requires stimulation of both DA and NA receptors.     

Screening Microalgal Cultures in Search of Microbial Exopolysaccharides with Potential as Adhesives

Nearly 800 cultures from the Commonwealth Scientific and Industrial Research Organisation (CSIRO) Collection of Living Microalgae (CCLM) were screened for exopolysaccharide (EPS) production by examining the viscosity of conditioned media supernatants. We first established dose-response relationships for the viscosity of reference polysaccharides dissolved in microalgal growth media. Then, using the 40 most viscous CCLM cultures, we confirmed that the viscosity of culture supernatants correlated well with their total sugar (and thus EPS) content. The conditioned medium with the highest viscosity (6.55 cP, equivalent to 1.16 g/L xanthan gum) was produced by a non-axenic isolate of the cyanobacterium Microcystis aeruginosa f. flos-aquae. Two types of bacteria, designated CSIRO501 (Gram-positive) and CSIRO505 (Gram-negative), were subcultured from it. At 20 dry wt% sugar, an exopolymer preparation from CSIRO505 contained substantially more EPS than its counterparts from CSIRO501 or from axenic Microcystis cultures, and it resembled a well-known bacterial EPS (xanthan gum) in being much more effective at bonding wood than PVC. It bonded wooden lap joints with a dry shear strength of 1.5 MPa, four times the value obtained in equivalent tests of a commercial polyvinyl acetate (PVA) glue.     

EFFECT OF CHEMICAL AND TURBULENT TIME SCALES ON POLLUTANT FORMATION DURING COMBUSTION

The relative effects of turbulent dissipation and chemical reaction time scales on CO and NO formation from CH₄, combustion are qualitatively assessed. Due consideration is given to the respective roles played by the initial magnitude of the temperature fluctuations and their rate of change. Thus, it is shown that concentration levels of CO and NO increase with increasing temperature fluctuations at the start of reaction and that long characteristic dissipation times favor pollutant formation. For initially large levels of temperature fluctuations the results indicate that pollutant generation is essentially independent of the way temperature fluctuations evolve with time.