The growing importance of understanding and controlling particulate emissions from gasoline engines is outlined, and an experimental simulation approach is described which has the potential for exploring particle deposition/capture and oxidation phenomena under well-controlled conditions, thus avoiding some of the uncertainties involved in interpreting engine experiments. Artificially generated sub-100 nm carbon particles are introduced into a synthetic exhaust gas stream, simulating engine-out soot emissions. Initial experiments in insulated pipe flows have shown very little particle deposition or change in mean size for residence times up to 1–2 s at uniform temperatures up to 400°C and hydrocarbon concentrations up to 4000 ppm C1′ in line with the results of supporting analytical and computational studies. Further numerical predictions suggested that it might be possible to capture some 20–30 per cent of the particles by turbulent diffusion alone at higher gas flowrates more representative of those in engine exhaust pipes. The effect of two different catalysts and an uncoated monolith on particle size and concentration has been investigated at space velocities of 50000 and 100000 h−1, with an inlet gas temperature of 400°C. Particle penetration through the catalysts increased with particle size but in all cases exceeded 70 per cent, with no evidence of significant changes in particle mean size. In the next phase of experimental and modelling work, the contribution of thermophoresis to particle deposition in uninsulated pipes will be examined.

The coupled phase approach is extended to model sound propagation in an emulsion of two compressible, thermoviscous liquids. This provides an alternative to scattering theory for modeling sound propagation in emulsions in the low-acoustic radius regime. Predictions of the new theory are compared with predictions of multiple-scattering theory and experimental results for ultrasonic velocity and attenuation in an emulsion. For the particular set of experimental data used here, the coupled phase theory gives predictions close to the scattering theory predictions, and a better prediction of the dependence of the attenuation on volume fraction. A similar difference between the two theoretical approaches has been found in earlier work on coupled phase models for sound propagation in suspensions.

To determine whether the effects of platelet activating factor on the airways may be due to the production of leukotrienes we studied the effects of pretreatment with the selective cysteinyl leukotriene antagonist SK&F 104353-Z2 on the airway and cellular responses to inhaled platelet activating factor. Eight healthy men were studied in a randomised, double blind placebo controlled cross-over study. A single dose of platelet activating factor that caused a fall of at least 35% in specific airways conductance (sGaw) was determined initially for each subject. Challenge with this dose of platelet activating factor was then carried out on two further occasions after pretreatment with a single nebulised dose of SK&F 104353-Z2 or placebo. The % reductions in specific airways conductance and of partial flow at 30% of vital capacity (PVmax30) were less after SK&F 104353-Z2 than after placebo (22 versus 34 for sGaw, 19 versus 31 for PVmax30). The mean (95% confidence limits (CL] differences in the maximum % fall from control values for SK&F 104353-Z2 and placebo were -12.6 (-23.8, -1.4) for sGaw and -12.5, (-20.8 -4.2) for PVmax30. The mean % fall in neutrophil count was similar after SK&F 104353-Z2 (46%) and after placebo (50%) (95% CL of difference 13.6, 6.6). Bronchial responsiveness to methacholine did not increase above baseline values in any subject when measured two weeks after challenge by platelet activating factor. This study suggests that leukotrienes play a part in the response to platelet activating factor in man.

The volume flow rate of blood in the portal vein was measured using a duplex ultrasound system. The many errors inherent in the duplex method were assessed with particular reference to the portal vein and appropriate correction factors were obtained by in vitro calibration. The effect of posture on flow was investigated by examining 45 healthy volunteers in three different positions; standing, supine and tilted head down at 20 degrees from the horizontal. The mean volume blood flow in the supine position was 864 (188)ml/min (mean 1SD). When standing, the mean volume blood flow was significantly reduced by 26% to 662 (169)ml/min. There was, however, no significant difference between flow when supine and when tilted head down at 20 degrees from the horizontal.

A data collection system for gathering electrical impedance measurements from the human breast is described. The system consists of 16 electrodes which are held in a ring that encompasses the breast. The system, which is battery operated, is controlled by a microprocessor enabling computer control of electrode selection and storage of data.

Sir, The paper by Evans et al. (Archives, 1978, 53, 330) describing a simple method for measuring oxygen consumption contains inaccuracies I should like to correct. The assertion that methods using a lower flow rate 'almost certainly result in CO2 retention' is wrong. The method described by me (Smales, 1978) uses a flow rate of 1 1/min and by sampling continuously from the nares in a term infant we were unable to demonstrate any alteration in the CO2 profile using the Edward's medishield medical mass spectrometer. At 500 ml/min, however, baseline shift was observed. In addition when oxygen consumption was measured at various flow rates between 1 and 3 1/min no significant differences were observed. I would suggest that the reason for this is that when a constant bias flow is applied to the proximal channel, flow rates exceeding this may occur during expiration through the distal part of tubing. In the method described by Evans et al. the flow rate of mixed expiratory gases through the distal tubing is constant and must therefore be higher to avoid CO2 retention. Although they omitted my data from their list of comparative values of V02 in neonates, Evans et al. will find that there is also close agreement with previous workers. 0. R. C. SMALES Nottingham City Hospital, Hucknall Road, Nottingham NGS JPB

HLA antigens were determined in 37 patients with asbestosis and 37 matched controls with equivalent asbestos exposure but no pulmonary fibrosis. All had worked in the same textile factory. No significant differences in the prevalence of antigens were found between the two groups or between either group and controls who had not been exposed to asbestos. When the data were combined with findings from other pilot studies the previously suggested association between asbestosis and HLA-B27 was not confirmed. Subjects who were positive for HLA-B12 tended also to have advanced radiographic fibrosis. Asbestos workers without pulmonary fibrosis had an unexpectedly high frequency of HLA-BW5, which might indicate that this antigen protects against the development of pulmonary fibrosis.

Summary Methods for studying the stability over time of regression relationships are considered. Recursive residuals, defined to be uncorrelated with zero means and constant variance, are introduced and tests based on the cusum and cusum of squares of recursive residuals are developed. Further techniques based on moving regressions, in which the regression model is fitted from a segment of data which is moved along the series, and on regression models whose coefficients are polynomials in time are studied. The Quandt log-likelihood ratio statistic is considered. Emphasis is placed on the use of graphical methods. The techniques proposed have been embodied in a comprehensive computer program, timvar. Use of the techniques is illustrated by applying them to three sets of data.

Nitrogen corona treated polyethylene was found to adsorb larger quantities of iodine from dilute solution (<10−4M) than an equivalent untreated polyethylene. The extent of the preferential adsorption is related to the length of treatment in the corona and also upon the initial concentration of the iodine solution. This preferential adsorption is suggested to occur via an electrostatic mechanism through charges induced into the polymer surface by the corona.

Experiment has shown that the nitrogen corona-induced autohesion of polyethylene and the nitrogen-corona induced sorption of iodine by polyethylene both follow similar mechanisms. The controlling factor is postulated to be the formation of short-lived electrets within the polymer surface.

The resultant surface activation of polymers by corona discharges has been found to be markedly influenced by the type and purity of gases used in the corona. In this work it is shown that for the nitrogen gas corona treatment (15 KV, 15 mins) of polyethylene and polypropylene, traces of oxygen, >0.5% and <0.15% respectively, are sufficient to produce chemical changes in the polymer surface.

AbstractThe importance of data produced by gel permeation chromatography (GPC) in polymer engineering is emphasized. The steps involved in deriving a differential molecular weight distribution curve (dMWD) from the chromatogram obtained by GPC are outlined. Each step is described, indicating its importance. Several viscosity‐molecular weight relationships, useful in the production of relevant calibration curves from the polystyrene calibration, are included. The presentation of results and experimental procedures are given.

Abstract— The complexity of neonatal disease in puppies is discussed, and it is suggested that the term ‘Fading Puppy Complex (F.P.C.)’ be used until the aetiology is clarified.Infection of young puppies with some micro‐organisms (Streptococci, E. coli, Brucella and Toxoplasma) which have been implicated in the aetiology of the F.P.C., is described.Laboratory and clinical information, including treatment and prevention of this condition, is discussed.A survey of the literature shows that much more work is required to establish the true rôle of infectious organisms in the F.P.C.Résumé— L'auteur expose la complexité de la maladie des chiots nouveauxnés et propose qu'en attendant des connaissances étiologiques complètes, celle‐ci soit déignée par le terme “syndrome de dépérissement” (“Fading Puppy Complex”= F.P.C.).L'auteur décrit diverses infections dues à des micro‐organismes (streptocoques, E. coli, brucella et toxoplasme) qui seniblent intervenir dans l'étiologie du F.P.C.II examine ensuite les résultats de la recherche expérimentale et clinique, y compris les connaissances actuelles en matière de traitement et de prévention.L'étude des textes disponibles oblige à constater l'importance des travaux restant à faire pour établir le rôle des organismes infectieux dans le syndrome étudié.Zusammenfassung— Der Komplex der neonatalen Erkrankungen von Welpen wird erörtert, und es wird vorgeschlagen, dafür den Ausdruck “Fading Puppy Complex” (FPC) zu verwenden, bis die Ätiologie geklärt ist.Die Infektion junger Welpen mit einigen Mikroorganismen (Streptokokken, E. coli, Brucella und Toxoplasma), denen eine Rolle in der Ätiologie des FPC zugeschrieben wird, wird beschrieben.Laboratoriums‐ und klinische Daten, unter anderem auch über die Behandlung und Ver‐hütung dieses Zustands, werden besprochen.Eine Literaturübersicht zeigt, dass noch viel Arbeit zu leisten ist, um die wahre Rolle der infizier‐enden Organismen beim FPC aufiuklären.

Reduction of benzotrifuroxan with trimethyl, triethyl, or tri-isopropyl phosphite yields a complex of benzotrifurazan with the corresponding trialkyl phosphate. Benzotrifurazan has a complexing ability similar to that of 1,3,5-trinitrobenzene.