Study of a Resonator with a View Toward Using It to Measure the Dielectric Constant of Magnetically Treated Water-Dispersed Systems

We consider problems involved in measuring the dielectric constant when industrial intermediates of sugar production are exposed to transient electromagnetic fields. Based on our studies of the interaction between the water-dispersed system and the electromagnetic field, we suggest a measurement system using the spectral density of the output signal of a resonant circuit.     

An improved tool–holder model for RCSA tool-point frequency response prediction

In addition to the precise kinematic motions of the machine tools and spindles, machining accurate parts necessitates controlling the dynamic behavior of the tool tip with respect to the workpiece. High-fidelity models of tool-tip dynamics can be used to select operating parameters that improve the accuracy by reducing the effect of vibrations. To effectively model the tool-tip dynamics for arbitrary tool-and-holder combinations using the receptance coupling substructure analysis (RCSA) technique, highly accurate and numerically efficient models of the tool–holder dynamics are needed. In this paper, we present a tool–holder model that incorporates a spectral-Tchebychev technique with the Timoshenko beam equation to obtain a completely parameterized solution. Comparison of the tool–holder model to a three-dimensional finite elements solution shows that the dynamic behavior is captured with sufficient accuracy. The tool–holder model is then coupled with the experimentally determined spindle–machine dynamics through RCSA to realize a model of the tool-tip dynamics. The coupled model is validated through experiments for three different tool overhang lengths. The presented technique can be used to predict the tool-tip dynamics for different tool-and-holder combinations and for optimization studies without the need for extensive experimentation.     

EXTRACTION OF TITANIUM(IV) FROM AQUEOUS HYDROCHLORIC ACID SOLUTIONS INTO ALAMINE 336-M-XYLENE MIXTURES

Extraction of Ti(IV) from its aqueous hydrochloric acid solutions into organic Alamine 336-m-xylene systems was investigated. Extraction experiments were conducted with three different initial metal concentrations of 1, 3, and 6 mg/mL, each at three acidic molarities of 1, 5, and 10 M. It was observed that the extractability of Ti(IV) increases with increasing acidic molarities. Alamine 336 diluted with m-xylene was found to be a suitable extractant for Ti(IV) across this acidic range. In parallel, a mathematical model was developed to correlate metal extractability and Alamine 336 volume content. Optimal Alamine 336 contents were estimated for single-stage extraction.     

Double-walled carbon nanotube/polymer nanocomposites: Electrical properties under dc and ac fields

The electrical properties of the poly(methyl methacrylate:carbon nanotubes nanocomposites) have been investigated by direct current conductivity and complex impedance spectroscopy methods. The direct current conductivity results of the poly(methyl methacrylate):carbon nanotube as a nanocomposites show that the electrical conductivity property of the poly(methyl methacrylate) changes from insulating state to semiconducting state with incorporation of double wall carbon nanotube DWCNTs into insulating polymer matrix. The alternating current conductivity mechanism of the nanocomposites is controlled by the correlated barrier hopping mechanism. The correlated barrier hopping CBH model for intimate valence alternation pairs IVAP's describes the conduction mechanism of PMMA doped with (1%) DWCNTs, while correlated barrier hopping CBH model for non-intimate valence alternation pairs describes the conduction mechanism of PMMA doped with (5% and 8%) DWCNTs. The real part of the complex impedance decreases with the increase of the applied frequency which revealed that the PMMA:DWCNT nanocomposites behaves like semiconducting materials. The complex impedance Nyquist plots for PMMA doped with different concentration DWCNTs over are characterized by the appearance of a single semicircular arc whose radii of curvature decreases with increasing the temperature. Cole and Cole plots show the presence of temperature dependent electrical relaxation phenomena in the PMMA:DWCNT nanocomposites. The obtained electronic parameters confirm that PMMA:DWCNTs exhibit organic semiconductor behavior.     

Preparation of thin film alloys with electrodeposition from heterotrinuclear M1–M2–M1 complexes (M1: NiII, CuII; M2: CuII, CoII, ZnII, CdII)

M₁ ^II–M₂ ^II–M₁ ^II type linear complexes (where M₁ = Ni²⁺, Cu²⁺ and M₂ = Cu²⁺, Zn²⁺, Co²⁺ and Cd²⁺ were prepared and dissolved in dimethyl sulfoxide. They were then electrodeposited on mild steel surfaces by the use of rotating disc electrodes. The deposition potentials were determined from cyclic voltammetric i-E scans. The metal films deposited on mild steel surfaces were characterized with atomic absorption spectrometer (AAS), X-ray fluorescence (XRF) and ion chromatography (IC) methods. Although the stoichiometric quantity of M₂ metal cation was half of the M₁ metal cation in the complex, the amount of M₂ metal deposited upon the surface was markedly greater. The amount of M₂ ion deposited on the surface was found to increase with the hardness of the ion. The X-ray diffraction (XRD) patterns showed that the excessively deposited metal on the surface was in metallic form as well as alloy. The size of the deposited film particles was investigated by the use of atomic force microscope (AFM) technique and the particles were observed to be bigger than nanoparticle size.     

Importance of H(2)O(2)/Fe(2+) ratio in Fenton's treatment of a carpet dyeing wastewater

The effectiveness of the Fenton's reagent (H(2)O(2)/Fe(2+)) in the treatment of carpet dyeing wastewater was investigated under different operational conditions, namely, H(2)O(2) and FeSO(4) concentrations, initial pH and temperature. Up to 95% COD removal efficiency was attained using 5.5 g/l FeSO(4) and 385 g/l H(2)O(2) at a pH of 3, temperature of 50 degrees C. The H(2)O(2)/Fe(2+) ratio (g/g) was found to be between 95 and 290 for maximum COD removal. It was noteworthy that, keeping H(2)O(2)/Fe(2+) ratio constant within the range of 95-290, it became possible to decrease FeSO(4) concentration to 1.1 g/l and H(2)O(2) concentration to 96.3 g/l, still achieving nearly the same COD removal efficiency. The relative efficiencies of Fenton's oxidation and coagulation stages revealed that Fenton's coagulation removed organic compounds which were not removed by Fenton's oxidation, indicating that the Fenton's coagulation acted as a polishing step.     

Biological treatment and nanofiltration of denim textile wastewater for reuse

This study aims at coupling of activated sludge treatment with nanofiltration to improve denim textile wastewater quality to reuse criteria. In the activated sludge reactor, the COD removal efficiency was quite high as it was 91+/-2% and 84+/-4% on the basis of total and soluble feed COD, respectively. The color removal efficiency was 75+/-10%, and around 50-70% of removed color was adsorbed on biomass or precipitated within the reactor. The high conductivity of the wastewater, as high as 8 mS/cm, did not adversely affect system performance. Although biological treatment is quite efficient, the wastewater does not meet the reuse criteria. Hence, further treatment to improve treated water quality was investigated using nanofiltration. Dead-end microfiltration (MF) with 5 microm pore size was applied to remove coarse particles before nanofiltration. The color rejection of nanofiltration was almost complete and permeate color was always lower than 10 Pt-Co. Similarly, quite high rejections were observed for COD (80-100%). Permeate conductivity was between 1.98 and 2.67 mS/cm (65% conductivity rejection). Wastewater fluxes were between 31 and 37 L/m2/h at 5.07 bars corresponding to around 45% flux declines compared to clean water fluxes. In conclusion, for denim textile wastewaters nanofiltration after biological treatment can be applied to meet reuse criteria.     

Double Stimuli‐Responsive Isoporous Membranes via Post‐Modification of pH‐Sensitive Self‐Assembled Diblock Copolymer Membranes

Double stimuli‐responsive membranes are prepared by modification of pH‐sensitive integral asymmetric polystyrene‐b‐poly(4‐vinylpyridine) (PS‐b‐P4VP) diblock copolymer membranes with temperature‐responsive poly(N‐isopropylacrylamide) (pNIPAM) by a surface linking reaction. PS‐b‐P4VP membranes are first functionalized with a mild mussel‐inspired polydopamine coating and then reacted via Michael addition with an amine‐terminated pNIPAM‐NH₂ under slightly basic conditions. The membranes are thoroughly characterized by nuclear magnetic resonance (¹H‐NMR), Fourier transform infrared spectroscopy and X‐ray‐induced photoelectron spectroscopy. Additionally dynamic contact angle measurements are performed comparing the sinking rate of water droplets at different temperatures. The pH‐ and thermo‐double sensitivities of the modified membranes are proven by determining the water flux under different temperature and pH conditions.     

Ultrasound‐Propelled Nanoporous Gold Wire for Efficient Drug Loading and Release

Ultrasound (US)‐powered nanowire motors based on nanoporous gold segment are developed for increasing the drug loading capacity. The new highly porous nanomotors are characterized with a tunable pore size, high surface area, and high capacity for the drug payload. These nanowire motors are prepared by template membrane deposition of a silver‐gold alloy segment followed by dealloying the silver component. The drug doxorubicin (DOX) is loaded within the nanopores via electrostatic interactions with an anionic polymeric coating. The nanoporous gold structure also facilitates the near‐infrared (NIR) light controlled release of the drug through photothermal effects. Ultrasound‐driven transport of the loaded drug toward cancer cells followed by NIR‐light triggered release is illustrated. The incorporation of the nanoporous gold segment leads to a nearly 20‐fold increase in the active surface area compared to common gold nanowire motors. It is envisioned that such US‐powered nanomotors could provide a new approach to rapidly and efficiently deliver large therapeutic payloads in a target‐specific manner.     

Parameters affecting oleochemical production from waste bleaching earth via alcoholysis

The edible oil industry is one of the largest industries in the world. In the edible oil refining process, large amounts of waste are discarded every day. Evaluation of these wastes is vital for environmental issues. Most of this waste is due to the bleaching process in which bleaching earths are largely used. Due to its high adsorption capacity, bleaching earth adsorbs oil nearly 40% of its weight. In order to evaluate this waste for oleochemical production, alcoholysis reactions were investigated. Parameters affecting the reaction, such as catalyst type and amount, alcohol type, alcohol:oil molar ratio and temperature, were investigated. The reactions were conducted in the presence of different catalysts such as NaOH, NaOCH₃ and homogeneous alkali polymeric gel catalyst (HAPJEK) and performed at a temperature range of 60–78°C and in the presence of a catalyst (1–2% based on oil weight) at alcohol:oil molar ratios of 5:1–7:1. Based on optimisation by response surface methodology (RSM), the critical synthesis conditions for 210 min reaction time with a maximum of 85.8% methyl ester content were determined as temperature: 68.4°C, catalyst amount 1.5% based on oil weight and methanol/oil molar ratio: 6.4.