A study of hydrogen environment effects on microstructure property behavior of NASA-23 alloy and related alloy systems

This work is part of the overall advanced main combustion chamber (AMCC) casting characterization program of the Materials and Processes Laboratory of the Marshall Space Flight Center. The influence of hydrogen on the tensile properties and ductility behavior of NASA-23 alloy were analyzed. NASA-23 and other referenced alloys in cast and hipped conditions were solution treated and aged under selected conditions and characterized using optical metallography, scanning electron microscopy, and electron microprobe analysis techniques. The yield strength of NASA-23 is not affected much by hydrogen under tensile tests carried at 5000 psig conditions; however, the ultimate strength and ductility properties are degraded. This implies that the physical mechanisms operating would be related to the plastic deformation process. The fracture surfaces characteristics of NASA-23 specimens tensile tested in hydrogen, helium, and air were also analyzed. These revealed surface cracks around specimen periphery with the fracture surface showing a combination of intergranular and transgranular modes of fracture. It is seen that the specimens charged in hydrogen seem to favor a more brittle fracture mode in comparison to air and helium charged specimens. The AMCC casting characterization program is to be analyzed for their hydrogen behavior. As a result of this program, the basic microstructural factors and fracture characteristics in some cases were analyzed

Are buybacks back? Menu-driven debt-reduction schemes with heterogenous creditors

There is always some price that is low enough so that a debtor country gains by buying back some of its debts. Similarly, there is always some price that is high enough so that creditors gain by selling their debt claims. What is needed is a mechanism that allows trades to take place at some price within this range. One mechanism, the market buyback, has been called a boondoggle. However, market buybacks are too expensive from the debtor's point of view and faced with a buyback bid, each creditor has incentives to hold onto its claim unless the bid is larger than the value of debt after the deal. Concerted debt-reduction agreements can overcome this type of coordination failure, but they may be difficult to reach in practice because of the heterogeneity of creditors. The authors argue that the menu approach to debt reduction retains the advantages but not the inconvenience of buybacks and concerted agreements. They introduce a model of bank asset pricing in the presence of tax incentives and deposit insurance. They then derive the equilibrium level of exit and new money for a distributionof creditors facing a given menu program. They show that the optimal menu includes some positive level of debt repurchase in almost all cases - challenging the argument that buybacks are undesirable. The authors conclude that the menu program dominates the standard buyback and new money approaches.Banks&Banking Reform,Economic Theory&Research,Financial Intermediation,Financial Crisis Management&Restructuring,Municipal Financial Management

Chronic Pancreatitis Presenting as Recurrent Pleural Effusion

Chronic Pancreatitis presenting as recurrent pleural effusion is an uncommon and often unrecognized clinical syndrome. The effusion frequently occurs without clinical evidence of pancreatitis, but occasionally it may be associated with calcification and pseudocyst of the pancreas. They usually presents as an exudative effusion of unknown cause and characterized by very high levels of amylase in the pleural fluid. In this report, a case of massive pancreatic pleural effusions are presented which was recurrent initially right sided and few month later left side

Note on seasonal fishery of Holothuria (Metriatyla) scabra Jaeger from Pamban Island

Out of the nearly 200 species of sea cucumber known from the seas around India, about 75 species are reported from the shallow waters of the Indian coast. Of these about 12 species are commercially important. Holothuria scabra locally ceilled as 'Vella attai' is the dominant species exploited by fishermen by skin diving in the Palk Bay and Gulf of Mannar

Irreducible pseudo 2-factor isomorphic cubic bipartite graphs

A bipartite graph is {\em pseudo 2--factor isomorphic} if all its 2--factors have the same parity of number of circuits. In \cite{ADJLS} we proved that the only essentially 4--edge-connected pseudo 2--factor isomorphic cubic bipartite graph of girth 4 is $K_{3,3}$, and conjectured \cite[Conjecture 3.6]{ADJLS} that the only essentially 4--edge-connected cubic bipartite graphs are $K_{3,3}$, the Heawood graph and the Pappus graph. There exists a characterization of symmetric configurations $n_3$ %{\bf decide notation and how to use it in the rest of the paper} due to Martinetti (1886) in which all symmetric configurations $n_3$ can be obtained from an infinite set of so called {\em irreducible} configurations \cite{VM}. The list of irreducible configurations has been completed by Boben \cite{B} in terms of their {\em irreducible Levi graphs}. In this paper we characterize irreducible pseudo 2--factor isomorphic cubic bipartite graphs proving that the only pseudo 2--factor isomorphic irreducible Levi graphs are the Heawood and Pappus graphs. Moreover, the obtained characterization allows us to partially prove the above Conjecture