Reactive Crystallization Kinetics of K2SO4 from Picromerite-Based MgSO4 and KCl

In this work, the kinetic parameters, the degrees of initial supersaturation (S0) and the profiles of supersaturation (S) were determined for the reactive crystallization of K2SO4 from picromerite (K2SO4.MgSO4.6H2O) and KCl. Different reaction temperatures between 5 and 45 °C were considered, and several process analytical techniques were applied. Along with the solution temperature, the crystal chord length distribution (CLD) was continuously followed by an FBRM probe, images of nucleation and growth events as well as the crystal morphology were captured, and the absorbance of the solution was measured via ATR-FTIR spectroscopy. In addition, the ion concentrations were analyzed. It was found that S0 is inversely proportional to the reactive crystallization temperature in the K+, Mg2+/Cl−, SO42−//H2O system at 25 °C, where S0 promotes nucleation and crystal growth of K2SO4 leading to a bimodal CLD. The CLD was converted to square-weighted chord lengths for each S0 to determine the secondary nucleation rate (B), crystal growth rate (G), and suspension density (MT). By correlation, from primary nucleation rate (Bb) and G with S0, the empirical parameters b = 3.61 and g = 4.61 were obtained as the order of primary nucleation and growth, respectively. B versus G and MT were correlated to the reaction temperature providing the rate constants of B and respective activation energy, E = 69.83 kJ∙mol−1. Finally, a general Equation was derived that describes B with parameters KR = 13,810.8, i = 0.75 and j = 0.71. The K2SO4 crystals produced were of high purity, containing maximal 0.51 wt% Mg impurity, and were received with ~73% yield at 5 °C

Column bioleaching of fluoride-containing secondary copper sulfide ores : experiments with Sulfobacillus thermosulfidooxidans.

Bioleaching is a mature technology, which is widely employed commercially in the leaching of primary sources of metals (ores, concentrates, and mine residues). The current work discussed the effects of aluminum sulfate additions to the growth medium, PLS recirculation and bleeding on the column bioleaching of secondary copper sulfide ores with a significant content of fluoride-containing minerals. Fluoride is toxic to bacteria at the pH of bioleaching but its toxicity may be overcome in the presence of soluble aluminum and ferric iron. Therefore, experiments were carried out in 10 ? 100 cm height aerated columns, loaded with 10 kg of crushed and agglomerated copper ore and inoculated with Sulfobacillus thermosulfidooxidans. Initially, fluoride concentrations of up to 2.5 g/L in the pregnant leach solution were observed due to the fast dissolution of fluoride-bearing minerals. Aluminum was added to the leaching solution to reduce the Al/F ratio so that the concentration of HF (the main toxic species) was decreased, but while the total fluoride concentration was higher than that of aluminum, the bacterial population as low. Therefore, the current work emphasizes that it is possible to set up conditions to enable bioleaching even at high fluoride concentrations. Following this approach, copper extractions above 90% were achieved for a H2SO4 consumption ranging from 128.8 to 206.1 Kg/ton

Triple Co-Administration of Ivermectin, Albendazole and Praziquantel in Zanzibar: A Safety Study

This paper describes how the use of three drugs which are used separately in mass drug distribution programmes when given together appear safe for use in large populations which have been previously treated with the same drugs separately (Mectizan [ivermectin], albendazole and praziquantel). The target diseases—lymphatic filariasis, soil-transmitted worms and schistosomiasis—were prevalent in Zanzibar up to 2000 but have been largely controlled by mass drug administration. The Ministry of Health and Social Welfare, with the support of WHO, initiated a small scale trial in a population of triple therapy in over 5,000 people initially in two sites, and having found there were no severe adverse events associated with the combined treatment then upscaled to treat the whole of the eligible population of over 700,000. Similarly, there were no severe adverse events. This is the first time the three drugs have been used together at the same time at scale in Africa and provide a basis for expansion of integrated preventive chemotherapy of helminths (worms). The next steps need to be initiated in populations which have heavier worm loads and such interventions need to be subject to close monitoring and ethical review

VARIATION OF THE LATTICE-PARAMETERS OF A BI-BASED SUPERCONDUCTOR WITH TEMPERATURE

Variation of the lattice parameters and thermal expansion coefficients of Bi-2223 superconductor have been measured from room temperature up to the melting point using X-ray diffraction. The lattice parameters (a and c) gradually increase up to about 250 degrees C. Between 250 degrees C to 450 degrees C the variation of the lattice parameters are quite anomalous, in that a remains almost constant while c decreases. From 450 degrees C to 600 degrees C both parameters gradually increase. Above 650 degrees C the structure of Bi-2223 becomes unstable. The initial thermal expansion coefficient along the c-axis is about four times that along the a-axis. Similar large anisotropy has also been observed in the measurements of the stress of Bi-2223

Detection of streptococcus pneumoniae in commercially-made silicone pacifiers used by infants and toddlers in selected barangays of Dasmarinas City, Cavite

Pacifiers are frequently used by children to substitute breastfeeding and as a comfrot item, they also bear the risk of carrying pathogenic bacteria that can make their users sick. The bacteria this study focuses on is Streptococcus pneumoniae, which causes diseases like pneumonia, meningitis, acute otitis media, and more. The study aims to determine the bacteria\u27s morphological characteristics as obtained from the pacifier samples, affirm their presence, and determine whether there is a significant presence of Streptococcus pneumoniae in the representative samples as exhibited by their colony count. Pacifiers collected from three barangays in Dasmarinas, Cavite were swabbed and underwent serial dilution and spread plating in a Blood Agar Plate No Streptococcus pneumoniae was detected in any of the samples, most bacteria found were various strains of bacillus and cocci. As the study focuses on detection, data such as the presence of Streptococcus pneumoniae or other bacteria were interpreted through a frequency distribution table