The small signal admittance of carbon implanted p-n diodes

In this paper we consider, in detail, how the introduction of radiation damage centres, produced by the implanation of carbon ions, affects the small signal admittance of silicon p-n diodes. Thermally stimulated capacitance measurements are used to obtain the charge states and activation energies of the damage centres. For carbon doses between 1 × 10¹¹ cm^?2 and 1 × 10¹² cm^?2 two trapping levels are observed with activation energies of E_t?E_v=0·31 eV and E_c?E_t=0·37 eV, and for doses between 5 × 10¹² cm^?2 and 5 × 10¹³ cm^?2 an extra level appears with an energy of E_c?E_t=0·25 eV. A study is made of the effects of these damage centres on the small signal capacitance and conductance of the diodes under forward bias. The results are interpreted in terms of a conductivity modulation effect, and it is proposed that this technique yields valuable information on the profile of the damage centres.     

Monitoring the run-time activity of algol 68-R programs

A program profiling system for the language Algol 68-R is described. The system provides deterministic information concerning the run-time behaviour of certain Algol language constructs. This is accomplished by preprocessing program texts prior to compilation using a syntax analyzer for Algol 68-R.     

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.     

Erythrocyte sodium and potassium in patients with hypokalaemia

1. The erythrocyte content of sodium and of potassium were measured in 231 unselected patients with hypokalaemia, and together with net ouabain-sensitive sodium efflux in patients with severe hypokalaemia, before (20 patients) and during potassium repletion (14 patients). 2. The erythrocytes of the patients with hypokalaemia compared with control subjects had on average an increase in sodium content, a decrease in potassium content and a reduction in the rate constant of ouabain-sensitive sodium efflux. All three changes had a similar curvilinear relation to the concentration of potassium in plasma with relatively little change in the measured variable unless the plasma potassium was very low. 3. There was a similar curvilinear relation between the final sodium and potassium content of normal erythrocytes and the potassium concentration of the medium in which they were incubated for 48 h in vitro. 4. These results suggest that the changes in the sodium and potassium content of erythrocytes in hypokalaemia are due to a direct inhibiting effect of the hypokalaemia on the activity of the sodium pump. 5. In many patients with hypokalaemia of moderate degree the increase in erythrocyte sodium content was less than expected from the effect in vitro of a low extracellular potassium concentration. This finding suggests that a compensatory change, presumably an increase in the number of sodium pumps, is a common event even in moderate hypokalaemia.     

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.     

Fate of Escherichia coli O157:H7 during composting of bovine manure in a laboratory-scale bioreactor

Inactivation profiles of Escherichia coli O157:H7 in inoculated bovine manure-based compost ingredients were determined by composting these ingredients in a bioreactor under controlled conditions. A 15-liter bioreactor was constructed to determine the fate of E. coli O157:H7 and changes in pH, moisture content, temperature, and aerobic mesophilic and thermophilic bacterial counts during composting. Fresh cow manure, wheat straw, cottonseed meal, and ammonium sulfate were combined to obtain a moisture content of ca. 60% and a carbon/nitrogen ratio of 29:1. The compost ingredients were held in the bioreactor at a constant external temperature of 21 or 50 degrees C. Self-heating of the ingredients due to microbial activity occurred during composting, with stratified temperatures occurring within the bioreactor. At an external temperature of 21 degrees C, self-heating occurred for 0 to 3 days, depending on the location within the bioreactor. E. coli O157:H7 populations increased by 1 to 2 log10 CFU/g during the initial 24 h of composting and decreased by ca. 3.5 log10 CFU/g near the bottom of the bioreactor and by ca. 2 log10 CFU/g near the middle and at the top during 36 days of composting. At an external temperature of 50 degrees C. E. coli O157:H7 was inactivated rapidly (by ca. 4.9 log10 CFU/g at the top of the bioreactor, by 4.0 log10 CFU/g near the middle, and by 5.9 log10 CFU/g near the bottom) within 24 h of composting. When inoculated at an initial level of ca. 10(7) CFU/g. E. coli O157:H7 survived for 7 days but not for 14 days at all three sampling locations, as indicated by either direct plating or enrichment culture. At the top of the bioreactor a relatively constant moisture content of 60% was maintained, whereas the moisture content near the bottom decreased steadily to 37 to 45% over 14 days of composting. The pH of the composting mixture decreased to ca. 6 within 1 to 3 days and subsequently increased to 8 to 9. Results obtained in this study indicate that large populations (10(4) to 10(7) CFU/g) of E coli O157:H7 survived for 36 days during composting in a bioreactor at an external temperature of 21 degrees C but were inactivated to undetectable levels after 7 to 14 days when the external temperature of the bioreactor was 50 degrees C. Hence, manure contaminated with large populations (e.g., 10(7) CFU/g) of E. coli O157:H7 should be composted for more than 1 week, and preferably for 2 weeks, when held at a minimum temperature of 50 degrees C.     

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.