Two-channel high-pressure helium-3 scintillation neutron detector

We have developed a two-channel, high-pressure /sup 3/He gas scintillation detector that operates in coincidence mode. The detector consists of two 16-mm diameter avalanche photodiodes viewing a 7-mm gap between them and mounted inside a stainless steel shell with 1.5-mm thick input windows. The gap is filled with a /sup 3/He+0.5%Xe gas mixture pressurized at 35 bar. The detector rejects signals generated by radiation interacting directly with the photodiodes and works as a "wall-less" detector, sensitive to interactions occurring only in the gas. The detector shows axial and radial position sensitivity to thermal neutrons within the gap between photodiodes. The position sensitivity is observed in good agreement with computer simulations. Applications are discussed.     

Titanium dioxide — Manufacture, environment and life cycle analysis: The tioxide experience

Conclusions  Pressure from an increasingly better informed and concerned public will continue to drive legislators to impose tighter environmental standards in all industries. In addition, the debate about sustainable economic development and environmental protection will become more sophisticated. Forward-looking companies will respond positively to societal pressures by contributing to the debate, developing their understanding of the nature of environmental impact and complying with legislation. Experience shows that LCA has a role to play in helping entire chains of production move towards more environmentally sustainable production methods whereby energy conservation and co-product manufacture are maximised and wastes for disposal minimised. This article is based on a paper given at the 15th SLF Congress in Lillehammer, Norway in May 1977     

Analysis of remotely sensed data: the formative decades and the future

Developments in the field of image understanding in remote sensing over the past four decades are reviewed, with an emphasis, initially, on the contributions of David Landgrebe and his colleagues at the Laboratory for Applications of Remote Sensing, Purdue University. The differences in approach required for multispectral, hyperspectral and radar image data are emphasised, culminating with a commentary on methods commonly adopted for multisource image analysis. The treatment concludes by examining the requirements of an operational multisource thematic mapping process, in which it is suggested that the most practical approach is to analyze each data type separately, by techniques optimized to that data's characteristics, and then to fuse at the label level.     

Structure of the human sensorimotor system. I: Morphology and cytoarchitecture of the central sulcus

Chromaffin cells grafted to the brain of animals with experimental parkinsonism and patients with Parkinson's disease can restore nigrostriatal functions. Mechanisms underlying these beneficial effects are unknown, but may include growth factors rather than the minute amounts of dopamine (DA) liberated from chromaffin cells. We now report that protein from chromaffin granules, which release their contents by exocytosis, promotes survival and uptake of 3H-DA of mesencephalic DAergic neurons in vitro and protect against N-methylpyridinium ion toxicity. This neurotrophic effect is accompanied by cell proliferation and mediated by astroglial cells induced in these cultures. Inhibition of cell proliferation and concomitant astrogliosis by 5-fluorodeoxyuridine and alpha-aminoadipic acid abolishes the trophic effect. Two highly specific inhibitors of the epidermal growth factor receptor (EGFR) signal transduction pathway, 4,5-dianilinophthalimide (10 microM) and tyrphostin B56 (10 microM), selectively block the neurotrophic capacity of chromaffin granule protein. As expected, they also block the mitogenic effects of EGF and TGF-alpha. However, these two mitogens do not mimic the pronounced mitogenic and trophic actions of chromaffin granule protein. Culture medium conditioned by mesencephalic cells pretreated with chromaffin granule protein promotes survival of DAergic neurons without increasing numbers of astroglial cells. The effective molecule is unlikely to be glial cell line-derived neurotrophic factor, whose mRNA is not detectable in cultures treated with chromaffin granule protein. We conclude that chromaffin granules contain a putatively novel growth factor, which signals through the EGFR and may be responsible for the known protective and restorative actions of chromaffin cell grafts to the lesioned nigrostriatal system.     

Demonstration of the conditions conducive to agglomeration of zinc calcine in fluidized bed roasters

Agglomeration in the fluidized bed roasting of zinc sulphide concentrate was investigated in a continuous pilot-scale fluidized bed roaster. Alone or together, low stoichiometric excess oxygen (<10%) and high temperature (>940 °C) contributed most significantly to agglomeration of zinc calcine particles. Only one test – with 0% excess oxygen at 940 °C – led to severe agglomeration and subsequent defluidisation. Neither large initial particle size nor low gas superficial velocity promoted agglomeration as much as the combination of low stoichiometric excess oxygen and high temperature.Lead sulphide, a common impurity in zinc sulphide concentrate, also appeared to have played a key role in agglomeration. Both low excess oxygen and high temperature favoured a high partial pressure of sublimated lead sulphide. Upon contact with oxygen, lead sulphide oxidised to lead oxide, which then precipitated as a liquid onto the rather inert bed particles. As a liquid, lead oxide formed coatings that caused small particles to adhere to larger ones, as well as liquid bridges that bound particles together.     

Gelgard—A new fire retardant for air and ground attack

Viscous water and gels have been proven to be more effective on forest fires than plain water. In 1963 and 1964, a new member of this family of fire retardants was tested. The authors describe the properties and characteristics of the compound, report the results of laboratory and field tests, and compare its effectiveness to that of plain water and other viscosity agents.