Design of a flotation cell equipped with ultrasound transducers to enhance coal flotation

Ultrasonic treatment is widely used for surface cleaning during physical, chemical and physico-chemical processes in mineral processing. Several research papers and a few industrial applications about the subject suggest that the mechanism behind the positive effect of ultrasound for mineral processing and especially flotation is due to formation of cavitation by ultrasonic energy. Within this study, coal floatability is investigated by use of a specially designed flotation cell equipped with ultrasound transducers with different power, frequency and geometry. The results indicate that ultrasonic treatment during coal flotation positively affects the quality and quantity of the properties of floated coals while using of lesser amounts of reagent than a conventional flotation system.     

Applications of fractional complex transform and $\left( \frac{G^{\prime }}{G}\right) $-expansion method for time-fractional differential equations

In this paper, the fractional complex transform and the $\left( \frac{G^{\prime }}{G}\right) $-expansion method are employed to solve the time-fractional modfied Korteweg-de Vries equation (fmKdV),Sharma-Tasso-Olver, Fitzhugh-Nagumo equations, where $G$ satisfies a second order linear ordinary differential equation. Exact solutions are expressed in terms of hyperbolic, trigonometric and rational functions. These solutions may be useful and desirable to explain some nonlinear physical phenomena in genuinely nonlinear fractional calculus.     

Determination of the Breakage and Wetting Parameters of Calcite and Their Correlations

This paper presents the breakage and wetting parameters of calcite mineral obtained experimentally and establishes a correlation between these characteristic parameters. The breakage parameter obtained from the different feed sizes of grinding is the specific rate of breakage (S_i). The wettability parameter, obtained from surface chemistry‐based processes such as contact angle measurements or flotation methods, is the critical surface tension of wetting of a solid or mineral (γ_c). Calcite mineral, studied for the determination of the above parameters and their correlations, was ground in a laboratory‐size ceramic ball mill with dry, wet and chemically aided grindings and tested extensively to determine the γ_c values by using a contact angle goniometer and a newly designed micro‐column flotation cell. The highest S_i value obtained was 0.35 min^?1 for sodium dodecyl sulfate (SDDS)‐aided grinding, and the lowest S_i value was 0.26 min^?1 for dry grinding of the ?600+425 feed in the mill. The γ_c values for calcite were obtained as 34.0–34.9 mN/m for SDDS‐treated calcite surfaces, 29.9–31.4 mN/m for sodium oleate‐treated surfaces and >72 mN/m for both dry and wet ground products whose surfaces were not treated chemically. Some correlations were established between the S_i and γ_c parameters; as the S_i increases, γ_c decreases, indicating that relatively more hydrophobic surfaces are broken faster for the largest sizes, resulting in higher S_i values with more fines (lower γ of B_{i, j}) in the finer size distribution region (i.e. ?150 μm).     

Raman spectral signatures of mouse mammary tissue and associated lymph nodes: normal,tumor and mastitis

Raman spectroscopy involves the interaction of light with the molecular vibrations and therefore can provide information about molecular structure, tissue composition and changes in its environment. We explored whether Raman spectroscopy can reliably distinguish mammary tumors from normal mammary tissues and other pathological states in mice. We analyzed a large number of Raman spectra from the tumor and normal mammary glands of mice injected with 4T1 tumor cells, which were collected using a high‐resolution (less than 4 cm⁻¹) Raman spectrometer at a fixed (785 nm) laser excitation wavelength and with 60 mW of laser power. The spectra of normal and tumor mammary glands showed consistent differences in the intensity of certain Raman bands and loss of some bands in the tumor spectra. Multivariate statistical methods—principal component analysis (PCA) and discriminant functional analysis (DFA)—were used to separate the data into different groups of mammary tumors, mastitis, lymph nodes contralateral and tumor‐cell‐injected sides, and normal contralateral and tumor‐cell‐injected sides. We demonstrate that this spectroscopic technique has the feasibility of discriminating tumor and mastitis from normal tissues and other pathological states in a short period of time and may detect tumor transformation earlier than the standard histological examination stage. Copyright © 2006 John Wiley & Sons, Ltd.     

Electrochemical behavior of tadalafil on TiO2 nanoparticles–MWCNT composite paste electrode and its determination in pharmaceutical dosage forms and human serum samples using adsorptive stripping square wave voltammetry

A sensitive and selective electroanalytical method for the determination of tadalafil (TAD) using adsorptive stripping square wave voltammetry at multiwalled carbon nanotube paste electrode (MWCNTPE) and modified TiO₂-multiwalled carbon nanotube paste electrode (TiO₂-MWCNTPE) was presented. The calibration curves were linear in the concentration range of 3.6–8.1 and 12.7–61.1 μM on MWCNTPE, 0.27–15.2 μM on TiO₂-MWCNTPE. The recommended method was successfully applied to the determination of the drug in tablets and human serum samples with good recoveries. The selectivity of the proposed method was considered in the presence of Ca²⁺, K⁺, Na⁺, 2-mercapto benzimidazole, thiourea, and dopamine by means of recovery tests. Interfering agents did not show considerable effect on TAD determination. No electroactive interferences from the tablet excipients and endogenous substances from biological material were detected. The possible electrooxidation pathway and the number of transferred electrons were also investigated.     

Theoretical and Experimental Heat and Mass Transfer Analysis for a Falling Film Outside a Grooved Tube

The heat and mass transfer from a grooved tube is investigated experimentally for a falling-film flow. The experiments are conducted on a helical trapezoidal grooved tube at three temperatures of the feeding water: 30°C, 35°C, and 40°C. The Reynolds number (Re) of the air ranges between 1,500 and 3,500. Nusselt number (Nu) is expressed as a function of the Prandtl number (Pr), Re for air (Re_a), Re for water (Re_w); Sherwood number (Sh) is expressed as a function of the Schmidt number (Sc), Re_a, and Re_w, and the correlation coefficients are determined.     

Biodegradation of methylene blue and carbaryl by Trametes versicolor laccase preparations in the presence of a mediator compound

Laccase from Trametes versicolar was immobilized on to acrylate based microbeads carrying epoxy or carbonate groups. The amounts of immobilized enzyme on the carbonate and epoxy groups were 24.6 and 9.7?mg/g, respectively. In the presence of a mediator (i.e., acetosyringone) almost 100% biodegradation was observed for both Methylene Blue dye (MB) and Carbaryl pesticide (CP) by the immobilized laccases, while in the absence of mediator, 63 and 71%, respectively. The immobilized enzyme was operated in a fluidized bed reactor for biodegradation of MB and CP for 24?h, and the initial activity lost was only 8.0 and 2.0%, respectively. The data show that the immobilized enzyme can effectively be utilized for complete degradation of organic pollutants in wastewaters.     

Phenoxazine polymers: synthesis and structure

Phenoxazine polymers were obtained for the first time under conditions of chemical oxidative polymerization in aqueous alcohols and in an interphase process. The interphase process gave products with the higher molecular weight. Dependencies of the yields and degree of polymerization of phenoxazine from polymerization method, concentration of reactants, their ratio, reaction temperature and time, as well as chemical structures of the obtained polymers depending on the synthesis conditions, were studied. The polyphenoxazine chain growth is accomplished by the C-C-addition at the para-position of the phenyl rings with respect to nitrogen. Even when an excess of oxidant was used, the polyphenoxazine structure has only phenyleneamine units. The polymers obtained are amorphous and thermally stable.     

Crystal and electronic structure and magnetic properties of CeRhPb

The new intermetallic cerium compound CeRhPb was synthesized by arc melting and studied by means of X-ray diffraction and magnetic measurements. The crystal structure determined from the single-crystal X-ray data is of the ZrNiAl type (space group P6¯2m). The compound was found to be a Pauli paramagnet with 4f⁰ ground state of the Ce atoms. The ab-initio band structure calculations performed without and with spin polarization confirmed the nonmagnetic character of the plumbide studied.     

A robust method for automated background subtraction of tissue fluorescence

This paper introduces a new robust method for the removal of background tissue fluorescence from Raman spectra. Raman spectra consist of noise, fluorescence and Raman scattering. In order to extract the Raman scattering, both noise and background fluorescence must be removed, ideally without human intervention and preserving the original data. We describe the rationale behind our robust background subtraction method, determine the parameters of the method and validate it using a Raman phantom against other methods currently used. We also statistically compare the methods using the residual mean square (RMS) with a fluorescence‐to‐signal (F/S) ratio ranging from 0.1 to 1000. The method, ‘adaptive minmax’, chooses the subtraction method based on the F/S ratio. It uses multiple fits of different orders to maximize each polynomial fit. The results show that the adaptive minmax method was significantly better than any single polynomial fit across all F/S ratios. This method can be implemented as part of a modular automated real‐time diagnostic in vivo Raman system. Copyright © 2007 John Wiley & Sons, Ltd.