It is shown that order-disorder relations in the distribution of the isomorphous substitutions are important in the characterization of different 2/1 phyllosilicates and in the determination of their behavior. These order-disorder relations are shown by selected area diffraction patterns obtained from single crystals. The range of layer charges corresponding to smectites (charge per half-cell <0.6) is that for which phyllosilicates are stable with disordered substitutions. Phyllites with charge >0.6 show anomalous diffusions which indicate that the distributions of exchangeable Ba ions are partially ordered; this result is taken as evidence that the isomorphous substitutions also are partially ordered.

Natural infection with the influenza virus is believed to generate cross-protective immunity across both types and subtypes. However, less is known about the persistence of this immunity and thus the susceptibility of individuals to repeat infection. We used 13 years (2005–2017) of surveillance data from Queensland, Australia, to describe the incidence and distribution of repeat influenza infections. Consecutive infections that occurred within 14 days of prior infection were considered a mixed infection; those that occurred more than 14 days later were considered separate (repeat) infections. Kaplan-Meier plots were used to investigate the probability of reinfection over time and the Prentice, Williams and Peterson extension of the Cox proportional hazards model was used to assess the association of age and gender with reinfection. Among the 188 392 notifications received during 2005–2017, 6165 were consecutively notified for the same individual (3.3% of notifications), and 2958 were mixed infections (1.6%). Overall, the probability of reinfection was low: the cumulative incidence was <1% after one year, 4.6% after five years, and 9.6% after ten years. The majority of consecutive infections were the result of two type A infections (43%) and were most common among females (adjusted hazard ratio (aHR): 1.15, 95% confidence interval (CI) 1.09–1.21), children aged less than 5 years (relative to adults aged 18–64 years aHR: 1.58, 95% CI 1.47–1.70) and older adults aged at least 65 years (aHR: 1.35; 95% CI 1.24–1.47). Our study suggests consecutive infections are possible but rare. These findings have implications for our understanding of population immunity to influenza.

A study has been carried out on the influence of acid concentration, time and temperature of reaction, liquid to solid ratio and chemical composition of the mineral on the extension and selectivity of the octahedral cations extracted during acid leaching of palygorskite. The mechanism of the extraction of Mg2+, Al3+, and Fe3+ is discussed on the basis of kinetic models fitted for a reacting-shell model, taking into account particle shape and the rate controlling step. A model is given from which kinetics parameters and the activation energy of the process are calculated. The different behaviour observed for the two palygorskites could be explained on the basis of their differences in surface areas.

Dans ce travail on a étudié l'influence des conditions expérimentales du traitement acide d'une sépiolite sur la vitesse d'extraction des ions Mg et la variation des propriétés texturales des produits résultants. On a élaboré un modèle cinétique pour l'attaque acide de la sépiolite ce qui nous a permis de calculer les paramètres cinétiques et, en dernier lieu d'obtenir des valeurs pour l'energie d'activation du processus.

Les analyses thermiques (A.T.P. et A.T.D.) de la palygorskite ont été réalisées entre 20 et 900° La palygorskite contient trois types d'eau nettement différenciés par leur rôle dans la structure. Cependant, les analyses thermiques indiquent un chevauchement des domaines de température où ces diverses molécules d'eau sont éliminées. L'interprétation des enregistrements à partir de la zone de plus haute température (qui correspond aux plus fortes énergies de liaison des molécules d'eau éliminées) permet d'obtenir un bon accord entre les résultats expérimentaux et ceux calculés à partir du modèle dioctaédrique du minéral.

La sépiolite chauffée à 300°C et 480°C sous vide a été étudiée avec un microscope électronique en haute-résolution. Les clichés donnent une photographie réelle des structures de la sépiolite naturelle et de la sépiolite anhydre, telles qu'elles ont été calculées par la cristallographie. Les résultats obtenus sont en accord avec ceux de la diffraction des rayons X et de la spectroscopie infrarouge.

Leaching of two palygorskites with different octahedral aluminium contents has been carried out in HCl at 20°–70°C. The acid concentration was varied in the range 0·05–6 mol. 1−1, using 4–500 g.g−1 liquid to solid ratios. Acid leaching of up to 60% of the octahedral cations did not provoke structural changes or amorphization of the samples. On the bases of the selectivity of extraction of Mg2+, Fe3+ and Al3+, it appeared that most of the octahedral edge positions are occupied by Mg2+, some by Fe3+, and practically none by Al3+. Differences in acid-leaching behaviour between the two palygorskites was better related to accessible surface than chemical composition.

A Parabolised Navier-Stokes (PNS) flow solver is used to predict the aerodynamic heating on the surface of a hypersonic vehicle. This case study highlights some of the main heat flux sensitivies to various conditions for a full-scale vehicle and illustrates the use of different complimentary methods in assessing the heat load for a realistic application. Different flight phases of the vehicle are considered, with freestream conditions from Mach 4 to Mach 8 across a range of altitudes. Both laminar and turbulent flows are studied, together with the effect of the isothermal wall temperature, boundary-layer transition location and body incidence. The effect of the Spalart-Allmaras and Baldwin-Lomax turbulent models on the heat transfer distributions is assessed. A rigorous assessment of the computations is conducted through both iterative and grid convergence studies and a supporting experimental investigation is performed on a 1/20th scale model of the vehicle’s forebody for the validation of the numerical results. Good agreement is found between the PNS predictions, measurements and empirical methods for the vehicle forebody. The present PNS approach is shown to provide useful predictions of the heat transfer over the axisymmetric vehicle body. A highly complex flow field is predicted in the fin-body-fin region at the rear of the vehicle characterised by strong interference effects which limit the predictions over this region to a predominately qualitative level.

The purpose of this study was to examine the effects of pre-university adiposity and physical fitness on changes of body weight and adiposity during the freshmen year. Twenty-nine freshmen (sixteen females and thirteen males) completed the study. Body weight and composition (dual-energy X-ray absorptiometry), waist circumference (WC), energy intake (7 d food diary) and activity-related energy expenditure (accelerometry) were measured in September, December and at the end of March. Peak oxygen uptake (VO2peak) was assessed at baseline only. Significant increases in body weight (1·9 (sd 2·0) kg, P < 0·05), BMI (0·6 (sd 0·7) kg/m2, P < 0·05), WC (2·7 (sd 3·0) cm, P < 0·05) and % body fat (BF) (3·1 (sd 2·3) %, P < 0·01) were noted in males, especially over the course of the first semester. No significant changes were observed in females. Results from correlation analyses showed that, baseline %BF was negatively associated with changes in body weight (r − 0·53, P < 0·01) and %BF (r − 0·41, P < 0·05) over the academic year. Baseline %BF predicted 27 % (P < 0·05) of the change in weight. Alcohol intake explained 34 % (P < 0·01) and 17 % (P < 0·05) of the changes in WC and %BF, respectively. The change in body weight and %BF were also positively associated with baseline VO2peak (r 0·51, P < 0·01; r 0·48, P < 0·01, respectively) while dietary restraint was negatively related to the changes in %BF (r − 0·43, P < 0·05). In summary, lower pre-university adiposity, higher VO2peak and higher alcohol intake are associated with greater changes in adiposity and body weight during the freshmen year.

Tetralogy of Fallot is often found in association with a wide variety of other cardiac lesions, but is rarely found in association with lesions causing obstruction to the left ventricular inflow or outflow. Subaortic stenosis has only rarely been reported in association with tetralogy of Fallot. We report a patient with Marfan syndrome who underwent repair of tetralogy of Fallot at five years of age. Discrete and progressive subaortic stenosis developed two years after the surgical correction, in a previously normal and unobstructed left ventricular outflow tract. Surgical removal of the acquired fibrous subaortic shelf was successful. Clinical signs of obstruction within the left ventricular outflow tract after surgical repair of tetralogy of Fallot should prompt further investigation to exclude the onset of acquired subaortic stenosis.