An electron microprobe study of the influence of beam current density on the stability of detectable elements in mixed-salts (isoatomic) microdroplets

This paper shows that a means of accurately measuring beam current during microprobe analysis of inorganic fluid microdroplets is essential, since certain elements were sublimated from such specimens under easily achieved beam current densities, i.e. S at 1·8 nA/μm², K at 2·5 nA/μm², Na at 3·5 nA/μm², P at 5·3 nA/μm². In comparison, Cl was volatilized even under the mildest conditions used (0·35 nA/μm²), and Ca, Mg and Co were stable under the severest operating conditions (7·1 nA/μm²). Elements were less stable in large (3 μm diameter) droplets than in small (1 μm) droplets under identical irradiation conditions. The onset of volatilization is a direct function of the current delivered per unit area and not of the total integrated dose. The addition of 50 g/l of urea to the mixed-salts (isoatomic) solution, or (a) the mounting of the droplets so that the carbon-celloidin support film was interposed between them and the electron source, and (b) top-coating the droplets with carbon, did not, in general, raise the threshold of volatilization of a given element, but did effectively retard the rate of loss at current densities above the volatilization threshold. A literature survey confirmed that similar losses can occur from biological tissue specimens, albeit at higher beam current densities. Finally, the possibility that local specimen heating during electron/specimen interaction is a cause of element loss during microprobe analysis is discussed.     

The performance of heat pumps in service-comparison of a computer model with a real installation

A comparison is made between a computer model which was developed in an earlier paper and experimental results in which a heat pump was used to heat a house during the heating season 1978–1979. The heat pump used was an air-to-water machine, and it is found that the radiator temperature in the experiment varies according to the heat demand of the house because of the effect of thermal inertia of the water and other thermal masses in the heat transfer system. The computer model simulates this effect, using hourly weather data to calculate the heat demand of the house and assuming that the radiators run at the temperature necessary to supply the heat demand during each hour. The model also calculates the coefficient of performance of the heat pump, and hence calculates the running cost in kilowatt-hours for each hour. The calculated running cost is compared with daily readings of kilowatt-hour meters. It is found that the comparison is very accurate during normal operation of the heat pump, with an accuracy of better than 1 per cent over a period of four months of the heating season, although the accuracy is not always quite so good. A comparison is also made between hourly calculated radiator temperatures and continuous recordings of flow and return temperatures. The comparison in this case is satisfactory, but there is a time lag due to the effect of thermal inertia of the building fabric which the computer model is not intended to simulate.     

Low temperature synthetic studies of beta-aluminas

Low temperature synthesis of beta-alumina leads to epitaxial mixtures of beta and beta″ types. Beta″ alumina is metastable unless stabilized with magnesium (and, presumably, lithium). Beta aluminas have not been seen below 950°C, but we are unable to show that beta is metastable at lower temperatures. Fine, preformed beta powders hardly sinter at all below 1500°C.     

Household energy consumption in the People's Republic of China

Results are presented of a study of household energy consumption in the People's Republic of China, focusing on fuel utilization for home cooking and heating and on electricity consumption by household appliances. Our analysis is based on some published data and on new data collected specifically for this study during 1981 on energy use by 343 families in four different regions of China: Shanghai, Liaoning, Guangdong, and Jiangsu. We characterize present Chinese household energy consumption, identify trends in energy use and lifestyle, and identify opportunities for increased efficiency of energy utilization in households.     

Power company fuel supply — Problems and solutions

A power company in the business of supplying electricity to its customers faces numerous problems associated with power production. One of its major problems is to supply its power plants with fuel and to use that fuel as economically as possible.The purpose of this paper is to discuss the difficulties that a power company has in supplying itself with fuel and to propose a technique that will produce a more prudent and economical use of fuel. The technique utilizes a multistage computer algorithm, which takes into consideration the power company's complete fuel supply process from coal mine to busbar. It requires a mathematical modeling of this process and allows for as much modeling flexibility as possible.     

High throughput methods for polymer nanocomposites research: Extrusion, NMR characterization and flammability property screening

A large number of parameters influence polymer-nanocomposite performance and developing a detailed understanding of these materials involves investigation of a large volume of the associated multi-dimensional property space. This multi-dimensional parameter space for polymer-nanocomposites consists of the obvious list of different material types under consideration, such as polymer and nano-additive, but also includes interphase surface chemistry, and processing conditions. This article presents combinatorial library design and high-throughput screening methods for polymer nanocomposites intended as flame-resistant materials. Here, we present the results of using a twin-screwn extruder to create composition-gradient library strips of polymer nanocomposites that are screened with a solid-state NMR method to rapidly evaluate the optimal processing conditions for achieving nanocomposite dispersion. In addition, we present a comparison of a new rapid Cone calorimetry method to conventional Cone calorimetry and to the gradient heat-flux flame spread method.