Mathematical Modeling of the Reduction of Safranin onto Chemically Modified Rice Husks in Stirred Tank Reactor Using Response Surface Methodology and Artificial Neural Network

ABSTRACT

The effluents coming from the dye industries are colored and polluted, and the disposal of these wastes into receiving waters causes damage to the water as well as the environment. The use of rice husk for the removal of dye from wastewater has been explored in a stir tank reactor. The effects of operation variables such as adsorbent dosage, contact time, dye concentration, initial pH, and agitation on the removal of safranin were investigated in a stirred tank reactor. The combined effect of various process parameters on dye removal were analyzed using response surface methodology (RSM), and the modeling of the process parameter had been done using the artificial neural network simulation method. It was observed that response surface methodology can determine the optimization of the process parameters and the model derived from the simulation of the artificial neural network (ANN) (deviation from experimental results was ～0.09%) described the process variable efficiently. It was observed that at the initial solution pH of 6.28 and adsorbent dosage of 15.63 g L^?1, dye removal of safranin was 97%.     

Safranin O Staining Using a Microwave Oven

We investigated the effects of microwave irradiation on a safranin O staining method for paraffin sections of formalin fixed rabbit larynx. The control sections were stained according to the conventional method, and the experimental sections were stained in microwave oven for 10 sec at 360 W in Weigert's iron hematoxylin, and for 30 sec at 360 W in fast green and 0.1% safranin O staining solutions. Light microscopic examination of the sections revealed that the microwave heating did not adversely affect the staining properties of cartilage tissue compared to the conventional staining method. Small differences such as darker staining of the matrix and shrinkage of the cytoplasm was observed in some microwave treated sections. The present study revealed that microwave application can be used safely for the safranin O method with the advantage of reduced staining time.     

ATP Accelerates Respiration of Mitochondria From Rat Lung and Suppresses Their Release of Hydrogen Peroxide

Lung mitochondria were isolated by differential centrifugation from pentobarbital-anesthetized male rats. One to three millimolar Mg²⁺-ATP increased the consumption of oxygen of lung mitochondria oxidizing 10 mM succinate > fourfold (P < 0.01) whereas ATP increased the respiration of liver mitochondria by < 35%. ATP also hyperpolarized partially uncoupled lung mitochondria in the presence of the mitochondria-specific antagonist, oligomycin. However, only 20% of the ATPase activity in the lung mitochondria was blocked by oligomycin compared to a blockade of 91% for liver mitochondria. We investigated the effect of reducing the non-mitochondrial ATPase activity in the lung preparation. A purer suspension of lung mitochondria from a Percoll gradient was inhibited 95% by oligomycin. The volume fraction identified as mitochondria by electron microscopy in this suspension (73.6± 3.5%) did not differ from that for liver mitochondria (69.1± 4.9%). ATP reduced the mean area of the mitochondrial profiles in this Percoll fraction by 15% (P <0.01) and increased its state 3 respiration with succinate as substrate by 1.5-fold (P < 0.01) with no change in the state 4 respiration measured after carboxyatractyloside. Hence, ATP increased the respiratory control ratio (state 3/state 4, P <0.01). In contrast, state 3 respiration with the complex 1-selective substrates, glutamate and malate, did not change with addition of ATP. The acceleration of respiration by ATP was accompanied by decreased production of H₂O₂. Thus ATP-dependent processes that increase respiration appear to improve lung mitochondrial function while minimizing the release of reactive oxygen species.     

A rapid and quantitative safranin‐based fluorescent microscopy method to evaluate cell wall lignification

One of the main characteristics of plant cells is the presence of the cell wall located outside the plasma membrane. In particular cells, this wall can be reinforced by lignin, a polyphenolic polymer that plays a central role for vascular plants, conferring hydrophobicity to conducting tissues and mechanical support for upright growth. Lignin has been studied extensively by a range of different techniques, including anatomical and morphological analyses using dyes to characterize the polymer localization in situ. With the constant improvement of imaging techniques, it is now possible to revisit old qualitative techniques and adapt them to obtain efficient, highly resolutive, quantitative, fast and safe methodologies. In this study, we revisit and exploit the potential of fluorescent microscopy coupled to safranin‐O staining to develop a quantitative approach for lignin content determination. The developed approach is based on ratiometric emission measurements and the development of an imagej macro. To demonstrate the potential of our methodology compared with other commonly used lignin reagents, we demonstrated the use of safranin‐O staining to evaluate and compare lignin contents in previously characterized Arabidopsis thaliana lignin biosynthesis mutants. In addition, the analysis of lignin content and spatial distribution in the Arabidopsis laccase mutant also provided new biological insights into the effects of laccase gene downregulation in different cell types. Our safranin‐O‐based methodology, also validated for Linum usitatissimum (flax), Zea mays (maize) and Populus tremula x alba (poplar), significantly improves and speeds up anatomical and developmental investigations of lignin, which we hope will contribute to new discoveries in many areas of cell wall plant research.     

Safranin O Staining Using a Microwave Oven

We investigated the effects of microwave irradiation on a safranin O staining method for paraffin sections of formalin fixed rabbit larynx. The control sections were stained according to the conventional method, and the experimental sections were stained in microwave oven for 10 sec at 360 W in Weigert's iron hematoxylin, and for 30 sec at 360 W in fast green and 0.1% safranin O staining solutions. Light microscopic examination of the sections revealed that the microwave heating did not adversely affect the staining properties of cartilage tissue compared to the conventional staining method. Small differences such as darker staining of the matrix and shrinkage of the cytoplasm was observed in some microwave treated sections. The present study revealed that microwave application can be used safely for the safranin O method with the advantage of reduced staining time.     

Combined histochemistry and autofluorescence for identifying lignin distribution in cell walls

Histological staining methods commonly used for detecting cellulose and lignin in cell walls were combined with epifluorescence microscopy to visualize differences in lignification between and within cellular elements. We tested our approach on sections of one-year-old branches of Fraxinus ornus L., Myrtus communis L., Olea europaea L., Pistacia lentiscus L. and Rhamnus alaternus L., containing both normal and tension wood. Sections were subjected to various staining techniques, viz. safranin O, safranin O/fast green FCF, and alcoholic solutions of safranin O/astra blue, according to the commonly accepted protocols. Stained and unstained sections were compared using both light and epifluorescence microscopy. Safranin O with or without counterstaining hid the strong fluorescence of vessel walls, cell corners and middle lamellae allowing the secondary wall fibers to fluoresce more clearly. Epifluorescence microscopy applied to stained sections showed more cell wall details than autofluorescence of unstained sections or white light microscopy of counterstained sections. This simple approach proved reliable and valuable for detecting differences in lignification in thick sections without the need for costly equipment.     

Isolation of cardiac mast cells in experimental Trypanosoma cruzi infection

Mast cells (MC) secrete diverse pre-stored chemical mediators that are pivotal in inflammatory and fibrotic etiologies, such as Trypanosoma cruzi-induced myocardiopathy. However, due to reduced number of cardiac MC, in situ and in vitro identification, and difficult tissue isolation, these cells are rarely addressed. In this work we optimized the identification of cardiac and peritoneal MC and developed an enzymatic method for MC isolation using control and T. cruzi-infected mice. MC were identified by: toluidine blue (TB); alcian blue (AB)/safranin (S); AB or a mixed solution composed by AB/S/TB. Previous evaluations of cardiac MC in T. cruzi infection were based on TB staining and our results using AB/S/TB solution showed an increase in, at least, five times the detection of MC. This mixed solution may improve the identification of MC populations also from skin, mucosa and tissues that are infected by other pathogens or under the influence of chronic inflammation, leading to more precise results. Furthermore, the appropriate combination of samples (frozen/unfixed/thick slices) and staining protocols can assure the best evaluation of MC. We have also isolated cardiac MC using collagenase and developed a highly efficient 60%/70% Percoll-graded protocol that enriched in, at least, 95% the population of cardiac MC.     

Combined histochemistry and autofluorescence for identifying lignin distribution in cell walls

Histological staining methods commonly used for detecting cellulose and lignin in cell walls were combined with epifluorescence microscopy to visualize differences in lignification between and within cellular elements. We tested our approach on sections of one-year-old branches of Fraxinus ornus L., Myrtus communis L., Olea europaea L., Pistacia lentiscus L. and Rhamnus alaternus L., containing both normal and tension wood. Sections were subjected to various staining techniques, viz. safranin O, safranin O/fast green FCF, and alcoholic solutions of safranin O/astra blue, according to the commonly accepted protocols. Stained and unstained sections were compared using both light and epifluorescence microscopy. Safranin O with or without counterstaining hid the strong fluorescence of vessel walls, cell corners and middle lamellae allowing the secondary wall fibers to fluoresce more clearly. Epifluorescence microscopy applied to stained sections showed more cell wall details than autofluorescence of unstained sections or white light microscopy of counterstained sections. This simple approach proved reliable and valuable for detecting differences in lignification in thick sections without the need for costly equipment.     

Spectroscopic studies on the interaction mechanisms of safranin T with herring sperm DNA using acridine orange as a fluorescence probe

Under the condition of physiological pH environment (pH = 7.40), the interactions of safranin T (ST) with herring sperm DNA were studied by means of spectral methods using acridine orange (AO) as a fluorescence probe. The spectroscopic characteristics of DNA–AO in the case of ST (along with the increase of concentration) were observed in an aqueous medium. The binding constants for ST stranded DNA and competitive bindings of ST interacting with DNA–AO systems were examined by fluorescence spectra, and the binding mechanism of ST with DNA was researched via viscosity measurements. All the testimony manifested that bonding modes between ST and DNA were evidenced to be intercalative binding and electrostatic binding, and the combining constant of ST with DNA was obtained. The binding of ST to DNA was driven by entropy and enthalpy through the calculated thermodynamic parameters (Δ_rH_m^?, Δ_rS_m and Δ_rG_m^?). Copyright © 2014 John Wiley & Sons, Ltd.     

Optimum Sorption Isotherm by Linear and Nonlinear Methods for Safranin onto Alkali-Treated Rice Husk

Rice husk, a lignocellulosic by-product of the agroindustry, was treated with alkali and used as a low-cost adsorbent for the removal of safranin from aqueous solution in batch adsorption procedure. In order to estimate the equilibrium parameters, the equilibrium adsorption data were analyzed using the following two-parameter isotherms: Freundlich, Langmuir, and Temkin. A comparison of linear and nonlinear regression methods in selecting the optimum adsorption isotherm was applied on the experimental data. Six linearized isotherm models (including four linearized Langmuir models) and three nonlinear isotherm models are thus discussed in this paper. In order to determine the best-fit isotherm predicted by each method, seven error functions namely, coefficient of determination (r ²), the sum of the squares of the errors (SSE), sum of the absolute errors (SAE), average relative error (ARE), hybrid fractional error-function (HYBRID), Marquardt's percent standard deviation (MPSD), and the chi-square test (χ²) were used. It was concluded that the nonlinear method is a better way to obtain the isotherm parameters and the data were in good agreement with the Langmuir isotherm model.