The yeasts Candida utilis and Saccharomycopsis fibuliger were propagated as a source of single-cell protein in a continuous, mixed, aerobic, single-stage cultivation on blancher water generated during potato processing. A series of steadystate experiments based on a two-level factorial design, half-replicate modified with an intermediate experiment, was performed to determine the effect of pH, 3.8 to 4.8; dissolved oxygen, 42 to 80% saturation; dilution rate, 0.17 to 0.31 h-1I and temperature, 27 to 320C on the amount of carbon consumed, the rate of carbon consumption (Rc), the amount of reducing sugar consumed, the rate of sugar consumption (Rg), the amount of protein produced, the rate of protein production (Rp), the yield from carbon, and the yield from reducing sugar. The results were analyzed by stepwise multiple regression and Fisher's least significant difference test. Analyses showed that high dilution rates resulted in increased Rc, Rg, and Rp and indicated that a rate of 0.31 h-1 was below the critical dilution rate. A temperature of 320C increased the amount of carbon consumed by 34%. A pH of 4.3 to 4.8 increased the amount of protein produced. The yield from carbon was constant, and the relatively high yield from reducing sugar indicated that other substrates were consumed. Dissolved oxygen was in excess at 42% saturation and above. Since C. utilis predominated the mixed cultures and amylase production appeared to be limited, a single-stage fermentation lacked efficiency. The experimental design allowed preliminary optimization of major environmental variables with relatively few experiments and provided a basis for future kinetic studies.

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Summary Spurred in part by literature published in the immediate aftermath of the severe acute respiratory syndrome epidemic in 2003, powered air‐purifying respirators have seen increased use worldwide during the COVID‐19 pandemic. Whereas these devices provide excellent protection of the user, there is an added element of risk during doffing and cleaning of the device. An additional layer of barrier protection, in the form of a polypropylene gown, to be worn over the hood and motor belt, can be used to minimise this risk. However, the device entrains air perpendicular to the lie of the gown, resulting in the impermeable material being sucked into the air intake, and partial occlusion of flow. In this report, we describe a clinical‐academic partnership whereby a bespoke filter guard was designed to disrupt airflow and prevent gown entrainment, thereby enabling full barrier protection of both the device and user. This intervention was simple, cheap, scalable and able to be mass produced.

The purpose o f this study was to investigate experimentally the effect of the homogeneous, gas phase thermal decomposition o f ozone upon heat transfer to ozone-oxygen mixtures in turbulent flow past a solid surface. Effluent from a silent discharge ozone generator passed through the 5/8-inch diameter, 1 0-inch long electrically heated glass test section. Seven inches from the test section inlet, local heat transfer coefficients were measured. Reynolds numbers in the test section were from 6000 to 13,000, and the wall temperatures investigated were from 623 O to 755" K. The experimental procedure consisted of measuring local heat transfer coefficients for both pure oxygen and ozone-oxygen mixtures (2.0 to 3.4% ozone b y volume) a t the some Reynolds number and temperature driving force. The chemical reaction reduced the heat transfer coefficient b y as much as 27%. A mathematical analysis based on the film theory model is in agreement with experimental results. HE transfer of heat between a solid surface and a fluid can be tion at the surface andl'or in the fluid. I n addition to a temperature gradient and the ordinary energy transport modes, concentration gradients are established as a result of the chemical reaction, and energy is also transported as chemical or configurational energy associated with the different diffusing molecules. At steady state, the reaction products and reactants diffuse in opposite directions. If there exists a significant difference in their chemical energies-i.e., if the heat of reaction is large-then a substantial net transport of energy results from the mass transfer.Heat transfer in a chemically reacting fluid is influenced by the usual physical properties and the fluid dynamics in the vicinity of the solid surface. However, the nature and rate of the chemical reaction itself are the key factors. If the reaction is sufficiently slow, its effect upon heat transfer can be neglected T .significantly affected by the occurrence of a chemical reac-and heat transfer coefficients computed by conventional methods. At the other extreme, for very fast reversible reactions, diffusion is the rate controlling mechanism, and chemical equilibrium can be assumed throughout the gas. The assumption of chemical equilibrium simplifies the general problem considerably in that the composition is a function of temperature and pressure, and the rate of the chemical reaction is not a factor in the analysis. I n this latter situation, the effect of the chemical reaction can be included as an additive contribution to the thermal conductivity and heat capacity of the fluid-that is, by considering effective thermal properties, the problem is equivalent to heat transfer in a nonreacting fluid with widely varying physical properties. The reversible dissociation of nitrogen tetroxide (N20&2N02) is an excellent example of a gas phase equilibrium reaction, and heat transfer i n this system has been thoroughly studied by many investigators (Brokaw,