Lehigh University

About: Lehigh University is a education organization based out in Bethlehem, Pennsylvania, United States. It is known for research contribution in the topics: Catalysis & Fracture mechanics. The organization has 12684 authors who have published 26550 publications receiving 770061 citations.

Fundamental study of thermal conduction in dry soils

Abstract: The thermal conductivity of the different soil components—mineral, liquids and air—varies across two or- ders of magnitude. Two studies are implemented to explore the role of contacts in heat conduction in dry granular mate- rials. The first set of experiments is designed to elucidate heat transfer at contacts, and it is complemented with a numeri- cally based inversion analysis for different local and boun- dary conditions to extract proper material parameters. Then, the thermal conductivity of dry soils is measured at different packing densities to address the relevance of coordination number and particle shape effects. Together, both studies confirm the prevailing effect of contact quality and number of contacts per unite volume on heat conduction in granular materials. Interparticle contacts and the presence of liquids in pores play a critical role in heat transfer, and determine the ordered sequence of typical thermal conductivity values: kair < kdry-soil < kwater < ksaturated-soil < kmineral.

Propagation and non-propagation of short fatigue cracks at a sharp notch

Abstract: — Sharply notched specimens of a structural low-carbon steel were fatigued under several ratios of the maximum to minimum loads. The growth behavior of a short fatigue crack near the notch tip was analyzed based on crack closure measurements. A fatigue crack first decelerates with increasing crack length, and then accelerates or becomes non-propagating depending on the applied stress. A similar deceleration is seen when the rate is correlated to the stress intensity range. The effective stress intensity range is a unique parameter in correlating the growth rate of a short crack for all the stress levels examined, and the relation is identical to that obtained for a long crack. By considering the increase in crack closure with crack length, a quantitative method is proposed for predicting the non-propagating crack length and the fatigue limit of notched specimens as a function of the applied stress and the notch geometry.

Measuring grief: A short version of the perinatal grief scale

Abstract: Despite a considerable number of studies, there are two major drawbacks in the literature on grief and bereavement. One is a lack of adequate and generally agreed upon measures for assessing grief. The second is a lack of ability to predict from existing measures the likelihood of what has been termed “chronic” or “pathological” grief reactions. This paper reports the results of the development of a bereavement measure for the study of perinatal loss which attempts to address these gaps. The measure is specific to a pregnancy-related loss, although it has the potential for adaptation to use for other types of loss. Analysis of responses from 138 women has resulted in the reduction of the original measure from 104 to a more manageable and almost equally comprehensive and reliable 33 items. In addition, a factor analysis has produced three factors, two of which indicate the possibility for longer-term and more severe grief reactions. Because of its sound psychometric qualities and interesting factor structure, the measure shows promise of being useful for both research and clinical purposes.

Reaction of Pyrrole and Chlorauric Acid A New Route to Composite Colloids

Abstract: Composite colloids of gold and polypyrrole were prepared using two different methods: 1, using pyrrole colloid, created by the oxidation of pyrrole by ferric chloride, to subsequently reduce chlorauric acid and, 2, oxidizing pyrrole monomer with chlorauric acid in a sodium dodecylbenzene sulfonate solution. In each case, the polypyrrole colloid consisted of irregularly shaped particles approximately 500 nm in diameter. The gold produced in each case was in the form of irregular spheres, approximately 407 nm in diameter in method 1 and 13 nm in method 2. X-ray photoelectron spectroscopy was used to determine the oxidation state of the species present. Transmission electron microscopy and light scattering data were used to determine the particle sizes of both gold and polypyrrole colloids. Energy dispersed spectrum X-ray analysis and electron diffraction were used to confirm the presence of metallic gold in the composite colloids. The second-order rate constant for the reaction of chlorauric acid with pyrrole in dilute solution was found to he 13 M -1 s -1 . Aqueous solutions of palladium, platinum, rhodium, cobalt, tin, silver, zinc, nickel, titanium, cadmium, mercury, arsenic, and selenium were also examined for their potential to act as oxidants to produce composite polypyrrole colloids. Palladium, platinum, and rhodium salts were suitable oxidants, producing polypyrrole in less than 12 h.