Rheology and ultrasonic properties of Pt57.5Ni5.3Cu14.7P22.5 liquid

The equilibrium and nonequilibrium viscosity and isoconfigurational shear modulus of Pt57.5Ni5.3Cu14.7P22.5 supercooled liquid are evaluated using continuous–strain-rate compression experiments and ultrasonic measurements. By means of a thermodynamically-consistent cooperative shear model, variations in viscosity with both temperature and strain rate are uniquely correlated to the variations in isoconfigurational shear modulus, which leads to an accurate prediction of the liquid fragility and to a good description of the liquid strain-rate sensitivity

Estimating Watershed Mercury Contribution to Lake Fort Smith State Park, Arkansas, USA

Mercury contamination associated with human activities poses global human health and environmental risks. A fish-consumption advisory has been in effect at Lake Fort Smith in central west Arkansas for more than a decade due to observed methylmercury concentrations in fish tissue. Lake Fort Smith is an important municipal drinking water supply and recreational resource. Water samples from the majority contributing tributary stream, Frog Bayou creek, were collected periodically, under differing hydrologic conditions in order to quantify the allochthonous mercury load delivered to the lake. Temperature, specific conductance, and turbidity data were collected and used to estimate dissolved organic carbon, methylmercury and mercury concentration in Frog Bayou creek. Dissolved organic carbon (DOC) concentration has been previously shown to have a strong correlation with total mercury (THg) and methylmercury (MeHg) presence and mobility in surface waters. Whereas a weak correlation was observed between DOC and THg concentrations (r2= 0.47), the relation between turbidity and THg was strong (r2 = 0.95), enabling use of turbidity as a proxy for the estimation of influx of THg in Frog Bayou creek. Analysis of water samples collected from streamflow indicated very little methylmercury contribution from the watershed, suggesting methylation of mercury is occurring predominantly within the body of Lake Fort Smith itself. Turbidity proved an inexpensive, real-time proxy for quantitative determination of mercury and methylmercury load in streamflow. This methodology provided better understanding of variations in mercury concentrations under differing hydrologic regimes and provided a tool for long-term watershed mercury load approximation to Lake Fort Smith

Presidential Address - The Social Service of Science

The extent to which society may be considered as an organism is still, I understand, a matter of controversy with sociologists. But without awaiting its adjudication, we may surely make use of a simile as ancient as that of the Apostle who spoke of individual Christians as members of one body, or as that of the wise old Roman, who taught the mutinous plebs the parable of the body politic, all of whose members were nourished by the well-fed patrician belly, and consider together this evening the social function of science in the body social

Anelastic to Plastic Transition in Metallic Glass-Forming Liquids

The configurational properties associated with the transition from anelasticity to plasticity in a transiently deforming metallic glass-forming liquid are studied. The data reveal that the underlying transition kinetics for flow can be separated into reversible and irreversible configurational hopping across the liquid energy landscape, identified with beta and alpha relaxation processes, respectively. A critical stress characterizing the transition is recognized as an effective Eshelby “backstress,” revealing a link between the apparent anelasticity and the “confinement stress” of the elastic matrix surrounding the plastic core of a shear transformation zone

Deformation of glass forming metallic liquids: Configurational changes and their relation to elastic softening

The change in the configurational enthalpy of metallic glass forming liquids induced by mechanical deformation and its effect on elastic softening is assessed. The acoustically measured shear modulus is found to decrease with increasing configurational enthalpy by a dependence similar to one obtained by softening via thermal annealing. This establishes that elastic softening is governed by a unique functional relationship between shear modulus and configurational enthalpy

Notes on the Lower Strata of the Devonian Series in Iowa

In a report recently made to the State Geological Survey, the writer communicates in detail some facts regarding the brecciated zone of the Devonian in Linn county, Iowa, and the terranes subjacent. The following is in part a brief summary of this report

Occurrence of Megalomus canadensis, Hall, in the LeClaire at Port Byron, Illinois

This common fossil of the Guelph of Canada has not been noted in the Le Claire beds of Iowa, or their immediate extension into adjacent states. Its occurrence, therefore, at Port Byron, Illinois, in the Barrett quarries one and one-half miles north of the town, is of special interest, since it shows a range much further to the west than hitherto observed, and a co-mingling of the Guelph and Niagara faunas in the Le Claire, similar to that in the so-called Guelph of Wisconsin. The specimens are well preserved, casts of the normal type not conforming to the variety of M. Compressus

Variation in the Position of the Nodes on the Axial Segments of Pygidium of a Species of Encrinurus

In defining the different species of the genus encrinurus (Emmrich) use has frequently been made of the disposition of nodes on the rings of the mid-lobe of the tail-shield. It is largely by this diagnostic that Foerste, for example, distinguishes E. thresheri from E. ornatus. Hall and Whitfield and the latter authors again, use the same criterion in separating E. ornatus from the European species figured in Murchison\u27s Siluria

Stochastic Metallic-Glass Cellular Structures Exhibiting Benchmark Strength

By identifying the key characteristic “structural scales” that dictate the resistance of a porous metallic glass against buckling and fracture, stochastic highly porous metallic-glass structures are designed capable of yielding plastically and inheriting the high plastic yield strength of the amorphous metal. The strengths attainable by the present foams appear to equal or exceed those by highly engineered metal foams such as Ti-6Al-4V or ferrous-metal foams at comparable levels of porosity, placing the present metallic-glass foams among the strongest foams known to date