A storage heat pump using an ‘ozone-friendly’ refrigerant

The paper describes the integration of a chemical and a vapour-compression heat pump for energy storage applications. The vapour-compression system is designed to operate using the UK cheap rate ‘Economy 7’ electricity tariff. The system is characterized thermodynamically using various refrigerant/absorbent pairs in the chemical storage circuit and an ozone-friendly refrigerant, R134a, in the vapour-compression circuit. Results indicate that the H₂O/Na₂S pair provides a high energy storage density and is the most suitable for use in this system. The paper also describes the design features of a domestic-sized version of this heat pump system. Air in the sunspace (conservatory) of a house was used as a heat source for the heat pump.     

A note concerning analytical expressions for Rice's upper-bound solution for fully plastic edge notched strips

A brief review of plasticity solutions for the edge-notched strips under combined axial force and bending moment is performed, and the lack of a suitable analytical model for certain regimes is identified. A formal derivation of Rice's upper bound model, which was evaluated by the original proposer via a semi-graphical procedure, is given, leading to exact analytical expressions for this model. Results are given in the form of a non-dimensional interaction (‘constraint’) diagram. The model has a number of applications, including studies on fracture mechanics testpieces.     

The physical chemistry of light-curable glass-ionomers

This paper reviews aspects of the physical chemistry of light-curable glass-ionomer cements. These materials have a tendency to undergo phase separation in solution and, when set, to take up water and swell. Other likely features of their behaviour include: (i) retardation of the ionic curing reaction by the presence of organic components; (ii) modification of the photochemical cure process by the presence of ionic species; and (iii) gradual phase separation on setting, leading to a domain structure in the solid state. The paper concludes that longer-term clinical studies are needed to demonstrate whether these features lead to durable materials or to materials containing inherent physico-chemical weaknesses that will limit their overall usefulness.     

Envelope glycoprotein gp120 of human immunodeficiency virus type 1 alters ion transport in astrocytes: implications for AIDS dementia complex

Infection by human immunodeficiency virus type 1 (HIV-1) is often complicated by a variety of neurological abnormalities. The most common clinical syndrome, termed acquired immunodeficiency syndrome (AIDS) dementia complex, presents as a subcortical dementia with cognitive, motor, and behavioral disturbances and is unique to HIV-1 infection. The pathogenesis of this syndrome is poorly understood but is believed to involve interactions among virally infected macrophages/microglia, astrocytes, and neurons. In this study, we show that exposure of primary rat and human astrocytes to heat-activated HIV-1 virions, or to eukaryotically expressed HIV-1 and HIV-2 envelope glycoproteins (gp120) stimulates amiloride-sensitive Na+/H+ antiport, potassium conductance, and glutamate efflux. These effects are blocked specifically by amiloride, an inhibitor of Na+/H+ antiport and by the selective removal of gp120 with immobilized monoclonal antibody. As a result of modulation of astrocytic function by gp120, the ensuing neuronal depolarization and glutamate exposure could activate both voltage-gated and N-methyl-D-aspartate-regulated Ca2+ channels, leading to increases in intraneuronal Ca2+ and neuronal death. These findings implicate the astrocyte directly in the pathogenesis of AIDS dementia complex.