This article discusses hearing disability in early modern Europe, focusing on medical ideas to demonstrate a profound shift in thinking about deafness over the course of the eighteenth century. Scholars have previously described changes in the social status of the deaf in the eighteenth century, pointing at clerics’ sympathy for the deaf and philosophers’ fascination with gestures as the origin of language, but there is remarkably little scholarship on the growing interest in deafness and hardness of hearing by physicians. From the seventeenth century onwards, however, medical men investigated earwax and mucus in the Eustachian Tube and developed theories about the propagation of sound waves via fluid airs and nervous juices in relation to hearing and deafness. This article argues that this focus on fluids brought about a new medical understanding of auditory perception, which viewed hearing and deafness not as dichotomous but as states along a continuous spectrum. As such, this article offers a new perspective on the study and treatment of hearing difficulties in early modern Europe, arguing that there was no solid dividing line between deafness and hearing; if anything, it was permeable and unstable.

The effects of boron and zirconium contents from 0 to 0.049 wt% on the casting fluidity, as-cast microstructure and mechanical properties of IN718C superalloy are systematically investigated. The results show that as the B or Zr content increases, the fluidity firstly increases and then decreases. The optimum fluidity is obtained at the pouring temperature of 1470 °C when the content of B is 0.0059 wt% or Zr is 0.042 wt%, respectively. The addition of Zr can lead to the formation of blocky laves phase, but B has no influence on microstructure morphology. Furthermore, the addition of B or Zr can effectively improve the tensile and stress life properties as well as casting fluidity of IN718C superalloy. As compared with IN718C master alloys, the tensile strength can increase 6.2–8.6% and stress life can be improved by 1.3 times when B content is 0.0059 wt%. In addition, when the alloy contains 0.042 wt% Zr, the tensile strength can increase 5.6–7% and stress life can increase 1.076 times than that of the master alloy.

The beneficial influence of three common spices was examined in experimental rats on: (i) the membrane fluidity of intestinal brush-border membranes (BBM), (ii) the activity of intestinal membrane-bound enzymes, and (iii) ultrastructural alterations in the intestinal epithelium. Groups of male Wistar rats were maintained on dietary black pepper (0·5 %), red pepper (3·0 %), ginger (0·05 %) and spice bioactive compounds piperine (0·02 %) and capsaicin (0·01 %) for 8 weeks. A membrane fluidity study using an apolar fluorescent probe showed increased BBM fluidity in all the spice-fed animals. This was corroborated by a decreased cholesterol:phospholipid ratio in the jejunal and ileal regions of the intestine. These dietary spices stimulated the activities of BBM enzymes (glycyl-glycine dipeptidase, leucine amino peptidase and γ-glutamyl transpeptidase) in the jejunal mucosa, suggesting a modulation in membrane dynamics due to the apolar spice bioactive compounds interacting with surrounding lipids and hydrophobic portions in the protein vicinity, which may decrease the tendency of membrane lipids to act as steric constraints to enzyme proteins and thus modify enzyme conformation. Scanning electronic microscopy of the intestinal villi in these spice treatments revealed alterations in the ultrastructure, especially an increase in microvilli length and perimeter which would mean a beneficial increase in the absorptive surface of the small intestine, providing for an increased bioavailability of micronutrients. Thus, dietary spices (black pepper, red pepper and ginger) were evidenced to induce alterations in BBM fluidity and passive permeability property, associated with the induction of an increased microvilli length and perimeter, resulting in an increased absorptive surface of the small intestine.

By using fluorescent probes the distribution and fluid properties of lipid and saccharide-bound molecules was assessed in the tegument of praziquantel (−) treated Schistosoma mansoni adult male worms. Our results show that higher amounts of glycoproteins and/or glycolipids are exposed in damaged areas of the membrane compared with undamaged ones. At damaged regions these molecules present high lateral diffusion coefficient and mobile fraction values which suggests that after praziquantel(−) treatment they are being shed by the worm into the medium. The lateral diffusion coefficient of the lipid analogue 5'-octadecanoyl aminofluorescein is unchanged in damaged or undamaged areas but the mobile fraction is significantly reduced at damaged areas. The immunological significance of these altered surface properties is discussed.

The lateral diffusion (DL) properties of the fluorescent lipid probe 5-N (octadecanoyl) aminofluorescein (AF18) inserted into the surface of muscle-stage larvae of Trichinella spiralis were investigated by fluorescence recovery after photobleaching. AF18 was not free to diffuse laterally in dormant larvae, and this remained unchanged after larval activation in vitro with trypsin and bile. However, a significant increase in surface fluidity of the probe was demonstrated (%R = 74·5; DL = 11·5 × 10−9 cm2/sec) when larvae invaded intestinal epithelial tissue following oral infection of mice. Membrane-permeant photoactivatable caged cyclic AMP was used to analyse the putative mechanism responsible for this increase in lateral diffusion in the parasite surface. Although incubation of larvae with 1–50 μM caged cAMP had no effect on surface fluidity, incubation with 100 μM caged cAMP induced a substantial increase in the lateral mobility of AF18 (%R = 64·3; DL = 8·3 × 10−11 cm2/sec) immediately following photo-activation of the caged messenger. This induced fluidity, however, was transient and the larval surface reverted to immobility within 15 min. These observations constitute the first reported measurement of the fluid properties of the surface of intracellular parasites, the first demonstration of the parasite surface fluidity altering as a result of host cell invasion and the first indication of a mechanism underlying changes in surface fluidity in parasitic helminths.