Thermodynamics of extraction of Re O 4 − from aqueous sulfuric acid media with Tri-n-butyl phosphate dissolved in kerosene

Rhenium distribution between Tri-n-butyl phosphate (TBP) dissolved in kerosene and sulfuric aqueous media is investigated under different temperatures, acidities, and TBP concentrations. Results show an exothermic extraction reaction with a distribution factor that decreases with the increase of the temperature and increases with the increase of the acidity and the TBP concentration. The stoichiometry of the reaction indicates neutralization of 1 mole of H⁺ with 1 mole of ReO ₄ ⁻ and solvating of a neutral molecule with four molecules of TBP. The structure of the complexes formed is, therefore, 4TBP · HReO₄. The apparent Gibbs free energy of the formation of 4TBP · HReO₄ from TBP, ReO ₄ ⁻ , and H⁺ is determined to be equal to −66,989 + 219.8 T J/mole.     

Predicting the Detonation Velocity of CHNO Explosives by a Simple Method

A simplified method is shown, based on a semi‐empirical procedure, to estimate the detonation velocities of CHNO explosives at various loading densities. It is assumed that the product composition consists almost of CO, CO₂, H₂O and N₂ for oxygen‐rich explosives. In addition solid carbon and H₂ are also counted for an oxygen‐lean explosive. The approximate detonation temperature, as a second needed parameter, can be calculated from the total heat capacity of the detonation products and the heat of formation of the explosive by PM3 procedure. The detonation velocities of some well‐known CHNO explosives, calculated by the simple procedure, fit well with measured detonation velocities and the results from the well‐established BKW‐EOS computer code.     

Feature Extraction in Fractional Fourier Domain for Classification of Passive Sonar Signals

Journal of Signal Processing Systems - The acoustic signals radiated from the marine vessels contain information about their machinery characteristics that can be useful for the detection and...     

Phase II monitoring of survival times with categorical covariates

Monitoring surgical outcomes is of paramount importance especially by accounting for health conditions of the patients prior to surgery. However, the problem arises as the effect of some covariates is pronounced but cannot be measured. In this paper, in order to deal with the effect of measured and unmeasured (categorical) covariates simultaneously, a class of survival analysis regression models called accelerated failure time (AFT) model and discrete frailty models is integrated and some Phase II risk-adjusted control schemes are devised to monitor the patients' lifetime. Three monitoring procedures including the cumulative sum (CUSUM), exponentially weighted moving average (EWMA), and probability limits-based control charts are developed in the presence and absence of censored observations. The performance analysis reveals that the proposed AFT frailty-based CUSUM control chart outweighs the competing counterparts in detecting shifts under various scenarios. Subsequently, two CUSUM control charts have been constructed corresponding to the cases of neglecting both the unmeasured and measured covariates and ignoring just the unmeasured covariate. The results clearly indicate that the detection ability for both of the mentioned CUSUM control charts declines, and including the unmeasured and measured covariates is critical while monitoring surgical outcomes. Finally, a real case study in a cardiac surgical center in the United Kingdom has been provided to investigate the application of the proposed AFT frailty-based CUSUM control scheme.     

Use of INT to determine the respiratory activity of immobilised and free Penicillium chrysogenum

The specific oxygen uptake rates (OUR) of k-carrageenan-immobilised and free cell cultures of Penicillium chrysogenum were determined using an oxygen electrode in a closed chamber. This was compared with the respiratory activity determined by the extent of staining with iodonitrophenyl tetrazolium chloride (INT). The degree of INT staining correlated with the OUR; an increase in INT deposition corresponding to an increase in the measured OUR. The INT staining technique could therefore be used to determine cell respiratory activity. In this way a profile of fungal cell activity throughout immobilised cell aggregates and free cell pellets was determined. In both types of cell culture, after the initial growth period only the peripheral biomass was observed to be active.     

Designing a double-negative metamaterial photonic crystal using the Thue–Morse sequence

Journal of Computational Electronics - This study investigates the propagation of electromagnetic waves through a one-dimensional quasi-photonic crystal with the transfer matrix method. Our...     

Experimental investigation of the effects of different chemical absorbents on wetting and morphology of poly(vinylidene fluoride) membrane

Membrane wetting is of one the most important factor that affects the CO₂ absorption efficiency in membrane contactors due to the increase of mass transfer resistance. In this study, the effects of different absorbents on the wettability of poly(vinylidene fluoride) membranes were investigated. Four absorbents including monoethanolamine, potassium carbonate–piperazine (PZ), potassium carbonate–monoethanolamine, and methyldiethanolamine–PZ were applied to investigate the effects of different absorbents on membrane wetting. Membrane properties before and after contact with absorbents were investigated using methods of thermogravimetric analysis, Fourier transform infrared spectroscopy, electron scanning microscope, and contact angle measurements. The results revealed that methyldiethanolamine and mixed absorbents containing methyldiethanolamine caused the most morphological changes in membrane. The results showed that reduction percentages of contact angle for water, K2CO3/PZ, K2CO3/MEA, MEA, and MDEA/PZ solutions were 14.52, 16.9, 21.19, 23.7, and 28.33, respectively, after 30 days immersion. The results also showed that potassium carbonate–PZ solution caused the least change in membrane wettability. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45543.     

Adaptation of Acidithiobacillus ferrooxidans to high grade sphalerite concentrate

In this study different strategies were employed for adapting Acidithiobacillus ferrooxidans cells to both Zn²⁺ ions and high grade sphalerite concentrate. The serial subculturing was found to be a very efficient strategy for adapting A. ferrooxidans cells to higher Zn²⁺ concentrations, as well as high grade sphalerite concentrate, provided that a suitable protocol was employed. Adaptation of A. ferrooxidans cells to 30 g/L Zn²⁺ significantly enhanced the rate of bioleaching of Zn²⁺ from high grade sphalerite concentrate. Preadaptation to Zn²⁺ ion also shortened the time required to adapt the cells to the concentrate. A. ferrooxidans PTCC 1642, exhibited a higher rate of Zn²⁺ bioleaching from high grade sphalerite concentrate compared to A. ferrooxidans DSMZ 583; however, due to the adaptation protocol employed the difference in performance of the two strains was not very great. Based on the results obtained in this study suggestions were given for the mechanisms during the adaptation of A. ferrooxidans cells to high grade sphalerite concentrate.