The structure of malaria pigment beta-haematin

Despite the worldwide public health impact of malaria, neither the mechanism by which the Plasmodium parasite detoxifies and sequesters haem, nor the action of current antimalarial drugs is well understood. The haem groups released from the digestion of the haemoglobin of infected red blood cells are aggregated into an insoluble material called haemozoin or malaria pigment. Synthetic beta-haematin (FeIII-protoporphyrin-IX)2 is chemically, spectroscopically and crystallographically identical to haemozoin and is believed to consist of strands of FeIII-porphyrin units, linked into a polymer by propionate oxygen-iron bonds. Here we report the crystal structure of beta-haematin determined using simulated annealing techniques to analyse powder diffraction data obtained with synchrotron radiation. The molecules are linked into dimers through reciprocal iron-carboxylate bonds to one of the propionic side chains of each porphyrin, and the dimers form chains linked by hydrogen bonds in the crystal. This result has implications for understanding the action of current antimalarial drugs and possibly for the design of new therapeutic agents.     

Redesigning a Large Supply Chain Management System to Reduce the Government Administration: A Socio-Functional Systems Approach

Redesigning managerial structure and redefining managerial processes in a large supply chain network in national scale is the main focus in this study. The considered supply chain is mainly under governmental management. Reducing the role of the government in managing the supply chain is a strategy pursued in this study. The supply chain is approached as a socioeconomic system and a methodology is designed to address important aspects of the system. The methodology is divided into two streams addressing two main aspects of a socioeconomic system—functional and social. Organizational cybernetics is the core of functional stream. The SCOR model has been used as a well-accepted supply chain management tool alongside the viable system model. The Social stream benefits from ideas of the methods which are used in the soft systems methodology and interactive planning. The methodology is applied in the considered supply chain network in which the final product is chicken meat. While supply chain management is mostly approached from a functional viewpoint, this study also considers its social aspects. Using soft methods as well as functional methods result in a systemic design which is functionally and socially desirable.     

Consensus supertrees: The synthesis of rooted trees containing overlapping sets of labeled leaves

Given two dendrograms (rooted tree diagrams) which have some but not all of their base points in common, a supertree is a dendrogram from which each of the original trees can be regarded as samples The distinction is made between inconsistent and consistent sample trees, defined by whether or not the samples provide contradictory information about the supertree An algorithm for obtaining the strict consensus supertree of two consistent sample trees is presented, as are procedures for merging two inconsistent sample trees Some suggestions for future work are made