Testing the flammability of materials exposed to arcs

Apparatus tests flammability and ignition characteristics of materials in close proximity to incandescent metal fragments or spalls ejected from intermittent short circuit arcs in air or oxygen rich atmospheres. It simulates a situation where an exposed live wire makes contact with a grounded member in areas containing organic matter

The relationship of feeder calf size and shape to rumen characteristics

Thirty days before they were marketed, feeder calves were measured, sampled and allotted to preconditioning or market-management systems at the farms of Tennessee and Kentucky feeder-calf producers during each fall marketing season (1977-1978). Body measurements were weight (WT). height (HT), length (LEN). depth (DP), width (WD) and fat thickness over the 12th rib (BF). Rumen samples were taken by the tube method from intact steers and volatile fatty acids (VFA), protozoa concentrations and pH were determined. Rumen liquid volume and in vitro gas producing potential of the fluid (GPP) were estimated. Principal component indices describing general calf size (SIZE) and calf shape (SHAPE) were calculated. Calves from two farms were used to study the relationship of SIZE and SHAPE to rumen function at FO before weaning. Rumen volume was correlated with WT, WD, HT, DP and SIZE. Acetate was related (P\u3c.01) to WT and BF. Depth and HT were the only individual body measurements that explained a large portion of the variation in protozoal concentration. Acetate and total VFA increased linearly (P\u3c.10) as SIZE increased. Similar trends were observed for acetate, butyrate and higher VFA. The relationship of acetate and total VFA to SHAPE was curvilinear. Similar curvilinear trends were observed in the relationship of Spirotricha and total protozoal concentrations with SHAPE. At FO the calves were randomly assigned to one of the three following market-management systems: 1) weaning and feeding a concentrate diet during the last 30 days before marketing and feeding hay at the orderbuyer barn (PW) and 2) allowing the calves to graze pasture with their dams during this period and feeding hay (NI) or a 50% concentrate diet at the orderbuyer barn (HE). Rumen characteristics were measured at the beginning and end of the market phase. In general, calf size was related to changes in the total rumen protozoal concentration and to changes in protozoa subclass and genera populations. Calf shape was generally related to changes in volatile fatty acid concentrations. The changes in VFA concentrations were generally smallest in PW calves and the relationship of these changes to shape was greatest in HE calves. The relationship of protozoal changes to shape was more varied among the three groups (NI, HE, and PW calves) and were more difficult to explain than the relationship with size. Significant relationships of calf size and shape to change in rumen characteristics of weanling calves and changes in rumen characteristics during market were observed. This relation ship was affected by market-management or preconditioning system to which the calves were subjected. In general, VFA concentrations and market changes were related to calf size and protozoal concentrations and market changes were related to calf shape

Effect of vessel wettability on the foamability of "ideal" surfactants and "real-world" beer heads

The ability to tailor the foaming properties of a solution by controlling its chemical composition is highly desirable and has been the subject of extensive research driven by a range of applications. However, the control of foams by varying the wettability of the foaming vessel has been less widely reported. This work investigates the effect of the wettability of the side walls of vessels used for the in situ generation of foam by shaking aqueous solutions of three different types of model surfactant systems (non-ionic, anionic and cationic surfactants) along with four different beers (Guinness Original, Banks’s Bitter, Bass No 1 and Harvest Pale). We found that hydrophilic vials increased the foamability only for the three model systems but increased foam stability for all foams except the model cationic system. We then compared stability of beer foams produced by shaking and pouring and demonstrated weak qualitative agreement between both foam methods. We also showed how wettability of the glass controls bubble nucleation for beers and champagne and used this effect to control exactly where bubbles form using simple wettability patterns

Drop impact behaviour on alternately hydrophobic and hydrophilic layered bead packs

A high level of water repellency in soils has an impact on soil hydrology, plant growth and soil erosion. Studies have been performed previously on model soils; consisting of close packed layers of glass spheres (140–400 μm in diameter), to mimic the behaviour of rain water on water repellent soils. In this study measurements were performed on multi-layered bead packs, to assess the interaction of water drops impacting layers consisting of different hydrophobic and hydrophilic layers. A high speed video camera was used to record the impact behaviour of water droplets on the bead packs focussing on the spreading of the droplet and the subsequent rebound behaviour of the droplet. Observations were made from the videos of the liquid marble effect on the droplet, whereby hydrophobic particles form a coating around the droplet, and how it differed depending on the arrangement of hydrophobic and hydrophilic layers within the bead pack. The droplet release height was varied in order to establish a relationship between impact velocity and the degree to which liquid marbling occurs, with higher impact speeds leading to a greater degree of liquid marbling. Measurements were also made to find the transition speeds between the three rebound conditions; rebound, pinning and fragmentation, showing an overall decrease in pinning velocity as the bead size increased