Distribution of metal onto the belt of a horizontal strip caster

This paper presents a new method for metal distribution onto the belt of a horizontal single belt strip caster. Water and liquid tin have been used to study the flow conditions in the feeding zone on the conveyor belt. Tests of a method presented in literature for metal distribution have been conducted and a new method that uses multiple parallel jets in order to obtain stable feeding conditions have been tested. This method gives a controlled way of maintaining a continuous liquid film and it also has a stable meniscus. The freezing problem with a triple point will also be eliminated by use of this method.     

Interpreting laser Doppler recordings from free flaps

Although the transfer of free flaps is nowadays accomplished with an increasing degree of safety, thrombosis of the microvascular anastomoses is still a problem. In order to avoid delay in re-operating, various methods for objective blood flow monitoring have been tried, among them Laser Doppler Flowmetry (LDF). When one reviews the literature, it is apparent that opinions differ about whether or not LDF is a reliable technique for this purpose. To focus on the need to interpret continuous recordings, this paper reports our findings in six latissimus dorsi free flaps chosen from our series of LDF monitoring procedures. One uneventful flap, no. 1, had an immediate postoperative LDF value of 4.5 perfusion units (PU). LDF values improved during the recovery period and the graphic recording showed fluctuations due to normal physiological variations of the blood flow in the flap. Another uneventful flap, no. 4, showed the same pattern, though at an appreciably lower level, 2 PU, on average. Flap no. 2 had an acceptably high value of 3.5 PU despite suffering a venous thrombosis. However, the LDF recording showed no fluctuations and the value declined gradually. Another flap, no. 3, showed fluctuations and blood flow was normal although the value decreased to 2.5 PU. In flap no. 5, any value between 2 and 3.5 PU could be obtained merely by adjusting the position of the probe in the holder. In no. 6, the LDF value suddenly dropped, accompanied by a decrease in the total amount of backscattered light, indicating venous obstruction which was confirmed at re-operation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Competitive protein adsorption to polymer surfaces from human serum

Surface modification by “soft” plasma polymerisation to obtain a hydrophilic and non-fouling polymer surface has been validated using radioactive labelling. Adsorption to unmodified and modified polymer surfaces, from both single protein and human serum solutions, has been investigated. By using different radioisotopes, albumin and Immunoglobulin G (IgG) adsorption has been monitored simultaneously during competitive adsorption processes, which to our knowledge has not been reported in the literature before. Results show that albumin and IgG adsorption is dependent on adsorption time and on the presence and concentration of other proteins in bulk solutions during adsorption. Generally, lower albumin and IgG adsorption was observed on the modified and more hydrophilic polymer surfaces, but otherwise the modified and unmodified polymer surfaces showed the same adsorption characteristics.     

Air flow and particle control with different ventilation systems in a classroom

Most ventilation and air conditioning systems are designed without much concern about how settling particles behave in ventilation air flows. For displacement ventilation systems, designers normally assume that all pollutants follow the buoyant air flow into an upper zone, where they are evacuated. This is, however, not always true. Previous studies show that high concentrations of settling respirable particles can be found in the breathing zone, and that the exposure rates can be a health hazard to occupants. The emphasis here is on how ventilation systems should be designed to minimize respirable airborne particles in the breathing zone. The supply and exhaust conditions of the ventilation air flow are shown to play an important role in the control of air quality. Computer simulation programs of computational fluid dynamics (CFD) type are used. Particle concentrations, thermal conditions and modified ventilation system solutions are reported.     

Adsorption of Novel Alkylaminoamide Sugar Surfactants at Tailor-made Surfaces

N,N-di(3-aminopropyl)dodecylamine (C12-Y-amine), N-dodecyl-N,N-di[(3-d-gluconylamido)propyl]amine (C12-DGA), N-dodecyl-N,N-bis[(3-lactobionylamido)propyl]amine (C12-DLA), N-dodecyl-N-[(3-lactobionylamido)propyl]amine (C12-LA), and ethoxylated N,N-di(3-aminopropyl)dodecylamine [C12-Y-amine with 4 and 8 ethylene oxide (EO)] have been synthesized, and their physical-chemical properties have been studied. Adsorption was measured at the air–water interface by the du Noüy ring method and at solid surfaces consisting of self-assembled monolayers (SAMs) of alkanethiols on gold using surface plasmon resonance. Results from surface tension measurements showed that adsorption at the air–water interface is pH dependent. At low pH, reduction in surface tension is less pronounced as a result of protonation of the amino groups of the surfactants. At the SAM model surfaces, generated by adsorption of alkanethiols or mixtures of alkanethiols on gold presenting methyl, hydroxyl, and carboxyl groups, the highest amount of adsorbed surfactant was obtained on a surface composed of a mixture of methyl and carboxyl groups. In general, the sugar-derived surfactants, DGA, DLA, and LA, adsorbed less than the ethoxylates. Surfactant biodegradation was investigated by the closed bottle test. Only C12-Y-amine was found to be readily biodegradable. However, the polyol surfactants were more biodegradable than the ethoxylates.

Surfactants in water-borne paints

The main uses of surfactants in water-borne coatings are discussed. Special attention is put on the use of surfactants in latex polymerization and in post-emulsification of binders, such as alkyd resins. The advantage of polymerizable surfactants as emulsifier is pointed out and the use of atomic force microscopy (AFM) to observe differences in film properties between formulations based on polymerizable surfactants and on conventional surfactants is illustrated. The paper further discusses the problem of competitive adsorption between surfactants and between surfactant and associative thickener in paint formulations.     

EAF Smelting Trials of Waste‐Carbon Briquettes at Avesta Works of Outokumpu Stainless AB for Recycling Oily Mill Scale Sludge from Stainless Steel Production

The EAF steel plant of Avesta Works, Outokumpu Stainless AB, has been used to perform smelting reduction trials of briquettes consisting of oily mill scale sludge, carbon and other wastes. A total of 7 briquette smelting trials were performed. The heats were processed smoothly smelting 3 t of briquettes or 3.4 mass‐% of metal charges. The quantities of FeSi powder and O₂ gas injected and electric energy supplied were increased to smelt briquettes of 6 t. No impacts were found on the analyses of the crude stainless steel tapped from the EAF during the trials. The results of the briquette smelting have been evaluated by referring to the data from the reference heats and results from earlier laboratory tests. The recovery of Cr, Ni and Fe elements from the briquettes was nearly complete and was found to occur mainly through carbon reduction. The slag masses were not increased in three trials as compared with the reference heats. There were moderate increases in the slag masses in four trial heats. The increases were, nevertheless, lower by 52‐69% than the slag masses generated by Sireduction of the briquette oxides. Afterwards, by referring results from the present trials, waste‐carbon briquettes amounting to 1‐3 t were smelted very smoothly in many of the EAF heats at Avesta Works to recycle the oily mill scale sludge and other wastes from stainless steel production.     

Discussion of Partitioning of synchronous machine windings forinternal fault analysis [Comments and authors' reply]

M.T. Holmberg et al. comment on the original paper by P.P. Reichmeider et al. (see ibid., vol.15, no.4, p.372-9, 2000). They point out that the authors do not appear to have mentioned as to how leakage inductance for part of the winding would be determined once the winding is partitioned. The original authors reply to the comments