Treatment of Iron Tailings at the Forecariah Guinea Mine - Guinea Conakry

Forecariah Guinea Mine SA (FGMSA) in Guinea - Conakry mines and processes Iron ore. About 0.5 Mt of tailings material has already been generated with additional 4000 tons generated daily. This paper presents a re-treatment technology for the Iron tailings obtained from the processing plant of FGMSA. Metallurgical tests were carried out on the tailings to determine which process route gives the most satisfactory result in terms of recovery and cost. Two representative samples (FCOPD-01 and FCDOP-02), taking from the tailings, were investigated. Particle Size Distribution (PSD) and chemical composition of various size fractions of representative samples of the tailings were performed. Dense Medium Separation (DMS) and Magnetic Separation (WHIMS) were also performed on a number of size fractions. The initial chemical composition of the various size fractions shows that the highest Fe grades were present in the +1 mm fractions at 58.8% and 58.6% for FCOPD-01 and FCOPD-02 respectively. The PSD of the tailings also indicated a mass yield of 77.9% for the +1 mm fraction and 22.1% for the -1 mm fraction. Contaminant Oxides, such as Al2O3 and SiO2 tend to be higher in the finer size fractions (-1 mm) of both samples. Result from the DMS analysis performed on the (-4 +0.5) mm fraction shows an underflow mass yields of 45.98% with Fe grade of 65.55% and overflow mass yield of 53.08% with Fe grade of just 13.5%. Magnetic separation (WHIMS) results on the (-4 +0.5) mm samples also gave varied mass yield and Fe grade at different magnetic intensities (3000 Gauss, 6000 Gauss and 10,000 Gauss). However, the highest Fe mass yield and grade produced from the magnetic separation were 18.10% and 50.8% respectively. The results show that DMS technique has the potential to re-treat the tailings at FGMSA. Keywords: Treatment, Iron ore, Tailings, Magnetic separation, Dense Medium Separatio

Intestinal Colonization Dynamics of Vibrio cholerae

To cause the diarrheal disease cholera, Vibrio cholerae must effectively colonize the small intestine. In order to do so, the bacterium needs to successfully travel through the stomach and withstand the presence of agents such as bile and antimicrobial peptides in the intestinal lumen and mucus. The bacterial cells penetrate the viscous mucus layer covering the epithelium and attach and proliferate on its surface. In this review, we discuss recent developments and known aspects of the early stages of V. cholerae intestinal colonization and highlight areas that remain to be fully understood. We propose mechanisms and postulate a model that covers some of the steps that are required in order for the bacterium to efficiently colonize the human host. A deeper understanding of the colonization dynamics of V. cholerae and other intestinal pathogens will provide us with a variety of novel targets and strategies to avoid the diseases caused by these organisms

Is There an Environmental Kuznets Curve for Sulfur?

The environmental Kuznets curve (EKC) hypothesis proposes that there is an inverted U-shape relation between environmental degradation and income per capita. Various explanations for this phenomenon have been put forward and some authors argue that important explanatory variables are omitted from conventional EKC estimates. Inclusion of these omitted variables is argued to increase the estimated "turning point" - the level of GDP per capita above which environmental degradation is declining. In this paper we use a new cross-section/time-series data base of sulfur emissions for a wide range of developed and developing countries. The methodology involves estimating EKCs for subsets of this database as well as for the sample as a whole. The results show that estimating an EKC using data for only the OECD countries, as has often been the case, leads to estimates where the turning point is at a much lower level than when the EKC is estimated using data for the World as a whole. The paper explores possible explanations of these results using Monte Carlo analysis, and other statistical tests.We conclude that the simple EKC model is fundamentally misspecified and that there are omitted variables which are correlated with GDP

Chaperone-like activity of tubulin

Tubulin, a ubiquitous protein of eukaryotic cytoskeleton, is a building block unit of microtubule. Although several cellular processes are known to be mediated through the tubulin-microtubule system, the participation of tubulin or microtubule in protein folding pathway has not yet been reported. Here we show that goat brain tubulin has some functions and features similar to many known molecular chaperones. Substoichiometric amounts of tubulin can suppress the non-thermal and thermal aggregation of a number of unrelated proteins such as insulin, equine liver alcohol dehydrogenase, and soluble eye lens proteins containing β- and γ-crystallins. This chaperone-like activity of tubulin becomes more pronounced as temperature increases. Aging of tubulin solution at 37° C also enhances its chaperone-like activity. Tubulin loses its chaperone-like activity upon removal of its flexible hydrophilic C-terminal tail. These results suggest that both electrostatic and hydrophobic interactions are important in substrate binding by tubulin and that the negatively charged C-terminal tails play a crucial role for its chaperone-like activity

Converting Fontan-Björk to 1.5- or 2-ventricle circulation

Patients with tricuspid atresia and ventricular septal defect have in the past occasionally undergone a Fontan with “Björk” modification to create a connection between the right atrium and the right ventricular outflow tract. While rarely performed now, patients with this physiology often face severe complications requiring re-intervention. We hypothesize that surgical conversion to a 2-ventricle or 1.5-ventricle circulation can improve hemodynamics, clinical status, and thus increase time to transplant. We present two successful cases to illustrate this idea

Speed control of a five-phase induction motor drive using modified super-twisting algorithm

The present work proposes an alternative for the inner current control based on the modified super-twisting algorithm with time delay estimation. Simulation results were carried out to verify the performance of the proposed robust control strategy for a five-phase induction motor drive. A stability analysis is also presented.CONACYT – Consejo Nacional de Ciencia y TecnologíaPROCIENCI

Improving the technology of boiled sausages with the addition of vegetable protein for the nutrition of school-age children

The content of the article is closely related to the fact that all modern society promotes a healthy lifestyle. Meat products are of particular importance for this concept-proper nutrition is also considered. Poultry meat is used as the main source of raw materials in the production of product formulations, as well as lentil flour as vegetable protein. During the study, it was found that when using protein raw materials from lentils, the stability of meat emulsions increased, and the proportion of fat decreased, and the proportion of protein in the products increased, which ensured a decrease in cholesterol and the overall energy value of the products. At the same time, the amino acid composition of the products is balanced, the consistency improves, and the yield increases. In the course of laboratory studies, the mass fraction of protein, fat, carbohydrates, moisture and nitrites in the proposed product was determined. A sample of the product with lentil flour was formed, which underwent organoleptic examination

A microscopic study of the fitness-dependent topology of the world trade network

Previous studies have suggested that the world-trade network belongs to the class of static hidden variable models. In this article we investigate the microscopic structure of the world trade network, that is the hidden variable correlation matrix of the network. The hidden variable is defined as a rank ordering of gross domestic products. This choice significantly reduces the noise in the statistical analysis found in previous studies. The hidden variable correlation matrix, that expresses the probability that a trade relationship between two countries of given fitness exists, suggests an attachment kernel that at least partially favours trading pairs or dissimilar fitness rather than the purely multiplicative one found previously. Additionally, we provide an in-depth look at the data source and reveal that first-order results, such as the degree distribution, exhibit significant qualitative differences depending on the data provider. Furthermore, we shed light on the intertemporal activity of international trade and point out that fluctuations occur mostly between countries with strong dissimilarities of fitness and connectivity

The International-Trade Network: Gravity Equations and Topological Properties

This paper begins to explore the determinants of the topological properties of the international - trade network (ITN). We fit bilateral-trade flows using a standard gravity equation to build a "residual" ITN where trade-link weights are depurated from geographical distance, size, border effects, trade agreements, and so on. We then compare the topological properties of the original and residual ITNs. We find that the residual ITN displays, unlike the original one, marked signatures of a complex system, and is characterized by a very different topological architecture. Whereas the original ITN is geographically clustered and organized around a few large-sized hubs, the residual ITN displays many small-sized but trade-oriented countries that, independently of their geographical position, either play the role of local hubs or attract large and rich countries in relatively complex trade-interaction patterns