Magnetic powder MnO-Fe \u3c inf\u3e 2 O \u3c inf\u3e 3 composite - A novel material for the removal of azo-dye from water

Fine powder adsorbents or catalysts often show better adsorptive or catalytic properties, but they encounter the difficulties of separation and recovery in application. In this study, four inexpensive magnetic powder MnO-Fe2O3 composites used as adsorbent-catalyst materials were prepared and characterized. These materials could be recovered efficiently by a magnetic separation method. Their adsorptive properties for the removal of an azo-dye, acid red B (ARB), from water and the regeneration of adsorbents containing ARB by catalytic combustion was studied. These powder adsorbents showed excellent adsorption towards ARB under acidic conditions. A very fast adsorption rate was observed and could be well described by a pseudo-second-order kinetics model. The adsorption capacity increased with increasing Fe content and surface area of the adsorbent, and the highest adsorption capacity of 105.3 mg/g was obtained at pH 3.5. The adsorption was not affected by the presence of Cl-, but was significantly affected by SO42-. The adsorbent containing ARB can be regenerated by catalytic combustion of adsorbed ARB at 400°C in air. Laboratory experiments demonstrated that this material is reusable. © 2004 Elsevier Ltd. All rights reserved

k-Value-based ferron assay and its application

Al(13) is notable for its promising application in many fields. It has been believed that Al(13) could be assayed in term of Al(b) derived from traditional ferron assay. But the inherent relation between Al(13) and Al(b) is not clear. Here, the new k-value-based ferron assay using nonlinear least squares analysis is suggested to resolve the ambiguity. The experimental results reveal that the moderate kinetics (k value) around 0.001 s(-1) can be ascribed to Al(13). In the short-term aging of freshly neutralized aluminum solutions with OH/Al molar ratio of 2.2, the rapid progress of Al(13)-like transformation into Al(13) can be traced by this method, whereas it may be masked by traditional ferron assay because the metastable intermediates also contribute absorbance to Al(b) fraction. Al(b) can only be regarded as Al(13) when Al(13) forms completely and becomes the stable specie in the matured solution. (C) 2009 Elsevier Inc. All rights reserved

Modified ferron assay for speciation characterization of hydrolyzed Al(III): a precise k value based judgment

The speciation of Al-OH complexes in terms of Al(a), Al(b) and Al(c) could be achieved by traditional ferron assay and Al(b) is generally considered as Al(13), however, the inherent correlation between them remains an enigma. This paper presents a modified ferron assay to get precise determination of Al(13) using nonlinear least squares analysis, and to clarify the correlation between Alb and Al(13). Two parallel reactions conforming to pseudo-first-order kinetics can simulate the complicate reactions between polynuclear complexes and ferron successfully. Four types of experimental kinetic constant (k value) of Al-OH complexes can be observed by this method when investigating three typical aluminium solutions. Comparing with the results of (27)Al NMR, the species with moderate kinetics around 0.001 s(-1) can be confirmed to resemble to Al(13) polycation. The other types of kinetics are also well-regulated in partially neutralized aluminium solutions with various OH/Al ratios (b values) in the range 0 similar to 2.5. It would provide potential means to trace the in-situ formation of Al(13) in dilute solutions such as coagulation with Al-based coagulant

Fractal Model for Acoustic Absorbing of Porous Fibrous Metal Materials

To investigate the changing rules between sound absorbing performance and geometrical parameters of porous fibrous metal materials (PFMMs), this paper presents a fractal acoustic model by incorporating the static flow resistivity based on Biot-Allard model. Static flow resistivity is essential for an accurate assessment of the acoustic performance of the PFMM. However, it is quite difficult to evaluate the static flow resistivity from the microstructure of the PFMM because of a large number of disordered pores. In order to overcome this difficulty, we firstly established a static flow resistivity formula for the PFMM based on fractal theory. Secondly, a fractal acoustic model was derived on the basis of the static flow resistivity formula. The sound absorption coefficients calculated by the presented acoustic model were validated by the values of Biot-Allard model and experimental data. Finally, the variation of the surface acoustic impedance, the complex wave number, and the sound absorption coefficient with the fractal dimensions were discussed. The research results can reveal the relationship between sound absorption and geometrical parameters and provide a basis for improving the sound absorption capability of the PFMMs

Parametric excitation of optomechanical resonators by periodical modulation

Optical excitation of mechanical resonators has long been a research interest, since it has great applications in the physical and engineering field. Previous optomechanical methods rely on the wavelength-dependent, optical anti-damping effects, with the working range limited to the blue-detuning range. In this study, we experimentally demonstrated the excitation of optomechanical resonators by periodical modulation. The wavelength working range was extended from the blue-detuning to red-detuning range. This demonstration will provide a new way to excite mechanical resonators and benefit practical applications, such as optical mass sensors and gyroscopes with an extended working range.NRF (Natl Research Foundation, S’pore)Published versio

Additional file 1 of Exploration of key factors in Gingival Crevicular fluids from patients undergoing Periodontally Accelerated Osteogenic Orthodontics (PAOO) using proteome analysis

Supplementary Material

Archform Comparisons between Skeletal Class II and III Malocclusions

<div><p>The purpose of this cross-sectional research was to explore the relationship of the mandibular dental and basal bone archforms between severe Skeletal Class II (SC2) and Skeletal Class III (SC3) malocclusions. We also compared intercanine and intermolar widths in these two malocclusion types. Thirty-three virtual pretreatment mandibular models (Skeletal Class III group) and Thirty-five Skeletal Class II group pretreatment models were created with a laser scanning system. FA (the midpoint of the facial axis of the clinical crown)and WALA points (the most prominent point on the soft-tissue ridge)were employed to produce dental and basal bone archforms, respectively. Gained scatter diagrams of the samples were processed by nonlinear regression analysis via SPSS 17.0. The mandibular dental and basal bone intercanine and intermolar widths were significantly greater in the Skeletal Class III group compared to the Skeletal Class II group. In both groups, a moderate correlation existed between dental and basal bone arch widths in the canine region, and a high correlation existed between dental and basal bone arch widths in the molar region. The coefficient of correlation of the Skeletal Class III group was greater than the Skeletal Class II group. Fourth degree, even order power functions were used as best-fit functions to fit the scatter plots. The radius of curvature was larger in Skeletal Class III malocclusions compared to Skeletal Class II malocclusions (<i>r_WALA3</i>><i>r_WALA2</i>><i>r_FA3</i>><i>r_FA2</i>). In conclusion, mandibular dental and basal intercanine and intermolar widths were significantly different between the two groups. Compared with Skeletal Class II subjects, the mandibular archform was more flat for Skeletal Class III subjects.</p></div