Process Chain for Numerical Simulation of IMLS

Additive layer manufacturing methods imply, among other advantages, extensive flexibility concerning their ability to realize mass customization. Despite various efforts towards process enhancement, numerous deficiencies concerning part distortion or residual stresses are still observable. The present work deals with the definition of an efficient process chain for numerical simulation of indirect metal laser sintering (IMLS), in order to improve dimensional accuracy. The underlying method is based on investigations of dilatometric behavior of iron based powder, which is integrated into reaction kinetic models and coupled with a finite element analysis (FEA). Thus, singular process steps, e. g. solid phase sintering, phase transformations or infiltration, are numerically modelled with adequate accuracy. Referring to thermomechanical simulation, possibilities for pre-scaling of part geometries are presented.Mechanical Engineerin

An Anti-Corruption Bureau’s Inexorable Endeavor: A Study of Malawi’s Cashgate Scandal

The “Cashgate” scandal has had far-reaching consequences for the southern African nation of Malawi and its people. Western donors suspended budgetary aid—circa $150 million annually—upon learning that civil servants and senior cabinet ministers in former President Joyce Banda’s administration had manipulated the government’s financial management system to embezzle more than$45 million over an eighteen-month period. As a precondition to the resumption of aid, the donors required that the government not only implement financial management reforms but also fully prosecute the perpetrators and recover the stolen assets. The donors’ position solidified when audits of Malawian government ledgers from 2009 to 2014 could not account for $356 million. This essay examines whether Malawi’s Anti-Corruption Bureau (ACB) has the institutional capacity to achieve the prosecutorial benchmarks set by Western donors. Despite the obstacles inherent in an overstretched and underfunded criminal justice system, the ACB has made some progress, with fifteen convictions on theft and money laundering charges, and$1.4 million in cash and property recovered. Yet, as this essay observes, the quest to secure convictions and recover assets in the more complex cases of senior officials will become quixotic unless the government provides the ACB with sufficient independence, authority, and resources. Lacking ACB operational success, donors seem disinclined to resume direct budgetary support to Malawi. And as Western countries retract, China moves in, extending its influence

Oscillatory instabilities during formic acid oxidation on Pt(100), Pt(110) and Pt(111) under potentiostatic control. II. Model calculations

A kinetic model is developed for the electrocatalytic oxidation of formic acid on Pt under potentiostatic control. The model development proceeds stepwise via a simple model of the electrocatalytic CO oxidation. The full model consists of four coupled, nonlinear ordinary differential equations. The scanned and stationary current/outer potential (I/U) behavior, stationary current oscillations, two-parameter bifurcation diagrams and stirring effects are simulated using realistic model parameters. The numerical findings are found to be consistent with the experimental results given by Strasser et al. The model reproduces period-1 as well as mixed-mode oscillations. Furthermore, a mechanistic analysis of the model was performed: two suboscillators are identified whose characteristics allow a plausible interpretation of the observed dynamics. After a classification of the suboscillators into previously described categories, an attempt is made to identify the minimal mechanistic requirements for electrochemical current oscillations

Rfx6 Maintains the Functional Identity of Adult Pancreatic β Cells.

SummaryIncreasing evidence suggests that loss of β cell characteristics may cause insulin secretory deficiency in diabetes, but the underlying mechanisms remain unclear. Here, we show that Rfx6, whose mutation leads to neonatal diabetes in humans, is essential to maintain key features of functionally mature β cells in mice. Rfx6 loss in adult β cells leads to glucose intolerance, impaired β cell glucose sensing, and defective insulin secretion. This is associated with reduced expression of core components of the insulin secretion pathway, including glucokinase, the Abcc8/SUR1 subunit of KATP channels and voltage-gated Ca2+ channels, which are direct targets of Rfx6. Moreover, Rfx6 contributes to the silencing of the vast majority of “disallowed” genes, a group usually specifically repressed in adult β cells, and thus to the maintenance of β cell maturity. These findings raise the possibility that changes in Rfx6 expression or activity may contribute to β cell failure in humans

catena-Poly[copper(I)-bis(μ-trifluoro­methane­sulfonato-κ2 O:O′)-copper(I)-bis(μ-trimethyl trithio­phosphite)-κ2 P:S;κ2 S:P]

The title compound, [Cu2(CF3SO3)2(C3H9PS3)2]n, crystallizes as infinite chains in which two trimethyl trithio­phosphite ligands and two trifluoro­methane­sulfonate anions bridge the essentially tetra­hedrally coordinated CuI ions in an alternating fashion. The P and one S atom of each trimethyl trithio­phosphite ligand are employed for coordination. The mol­ecular structure exhibits the rare motif of copper(I) bridged by two trifluoro­methane­sulfonate anions generating eight-membered rings