Preparation and Characterization of Activated Carbon from Microwave and Conventional Heated Almond Shells Using Phosphoric Acid Activation

Activated carbon production from almond shells using phosphoric acid activation agent was achieved by applying both conventional heating and microwave heating in succession. The morphology and surface properties of activated carbon were studied using thermogravimetric and differential gravimetric analysis, Fourier-transform infrared spectroscopy, scanning electron microscopy, and Brunauer–Emmett–Teller analysis. A surface area of 1128 m²/g was achieved by optimizing the microwave power (500?W), microwave application time (15?minutes), conventional heating time (45?minutes), conventional heating temperature (500?°C), and the phosphoric acid:sample ratio (0.7:1). An adsorption capacity of methylene blue of 148?mg/g and an iodine value of 791?mg/g was obtained for the prepared activated carbon.     

Decompositions of some weaker forms of continuity

The aim of this paper is to give decompositions of some weaker forms of continuity using the concepts of classes B ₁, B ₂, B ₃, αA and αC introduced by ourselves.     

Existence of positive solutions for nonlinear three-point problems on time scales

In this paper, by using fixed point theorems in cones, we study the existence of at least one, two and three positive solutions of a nonlinear second-order three-point boundary value problem for dynamic equations on time scales. As an application, we also give some examples to demonstrate our results.     

Synthesis of the possible carcinogenic dihydrodiol and diol epoxide of phthalazine

Inverse-Diels-Alder reaction of dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate with benzene cis-diol gave dihydrodiol containing the 1,4-dihydropyridazine ring. Attempts at oxidation of the dihydropyridazine ring with PIFA and MnO₂ resulted in the formation of 5- and 5,6-dihydroxy-phthalazine derivatives. The oxidation of the dihydropyridazine ring was achieved by way of photooxygenation. The phthalazine type dihydrodiol is unstable and easily undergoes aromatization. The Diels-Alder reaction of tetrazine with cyclohexadiene acetonide and epoxy-ketal cyclohexene as a dienophile was investigated. These reactions led to the possible carcinogenic phthalazine type of dihydrodiol and diol epoxide where the hydroxyl groups are protected.     

FTIR studies of vitamin E-cholesterol-DPPC membrane interactions in CH2 region

Binary and ternary mixtures of alpha-tocopherol (alphaT), cholesterol and dipalmitoyl phosphatidylcholine (DPPC) in the form of multilamellar liposomes have been investigated by Fourier Transform Infrared Spectroscopy (FTIR). Investigation of frequencies, bandwidths and band shapes of CH(2) stretching and scissoring bands indicate that the effect of alphaT is dominant in comparison with cholesterol and alphaT decreases the interaction of cholesterol with phospholipid membranes.     

Selective spectrophotometric determination of TNT in soil and water with dicyclohexylamine extraction

Contaminated land and groundwater remediation in military waste dumping sites often necessitates the use of simple, cost-effective, and rapid tests for detecting trinitrotoluene (TNT) residues in the field along with their dinitro-analogues. A simple, rapid, low-cost, and field-adaptable (on-site) colorimetric method was developed for quantifying TNT in the presence of RDX, PETN, picric acid, 2,4-DNT (dinitrotoluene), dinitrophenol, and dinitroaniline. Most commercialized methods for TNT assay-with the exception of Cold Regions Research and Engineering Laboratory of the U.S. Army (CRREL) method-use proprietary chemicals, and the color stability and intensity are highly dependent on the composition of the organic solution comprised of acetone or methanol. The developed colorimetric method is based on the extraction of TNT from water-acetone solution into an organic solvent mixture of dicyclohexylamine (DCHA)-isobutyl methyl ketone (IBMK) (10:1, v/v), filtration through a filter paper into a stoppered optical cell containing anhydrous sodium sulfate, and measurement of the absorbance of the organic extract at 531 nm after 5 min. The red-violet color of the extract was due to intermolecular charge-transfer (CT) between the electron attracting TNT and electron-donating DCHA, and the molar absorptivity for TNT in final organic solution was (1.16 ± 0.02) × 10⁴ L mol⁻¹ cm⁻¹.The R.S.D. of the slope of calibration line was 0.7%. The LOD of the method in the final organic phase was 0.38 μM TNT, and LOD values expressed on the basis of original soil TNT content were 0.5, 1.3, and 1.5 ppm (μg g⁻¹) for clay, loamy clay, and sandy soils, respectively. Unlike other spectrophotometric methods, the developed assay was basically tolerant to common cations and anions found in soil and water at 100-fold weight ratios, and to soil humic acids. Among a number of compounds that may be encountered in polynitro-explosive storage and waste reclaimation sites such as picric acid, dinitrophenol, 2,4-dinitrotoluene, dinitroaniline, RDX, PETN, and tetryl, only tetryl interfered with the developed TNT assay. Water tolerance and exploitability over a wide pH range were other superiorities over the CRREL method. The CT-complex was relatively stable, as the absorbance of the organic extract was not significantly influenced from the dilution of the water-acetone phase. Aside from the extractive-photometric procedure established for aqueous solutions, a simulated field colorimetric assay for TNT directly applicable to soil was also devised, based on direct color development in a 4:1 (v/v) acetone-dicyclohexylamine organic extract of soil at a liquid-to-solid ratio of 5 mL g⁻¹.     

Microemulsion photopolymerization of methacrylates stabilized with sodium dodecyl sulfate and poly(N-acetylethylenimine) macromonomers

Methyl methacrylate and butyl methacrylate were polymerized in oil-in-water microemulsions that were stabilized by sodium dodecyl sulphate (SDS). A poly(N-acetylethylenimine) (PNAEI) macromer was also included in the recipe, as a cosurfactant and a comonomer. Polymerizations were initiated by UV-irradiation. The average diameters of latex particles, obtained by STM, were in the range of 17-200 nm. The experimental data evidenced that the particle size was mainly dependent on the SDS/PNAEI ratio. Polymerization yields were around 75-85%. The synthesized copolymers have viscosity average molecular weights in the range of 2.1-2.4×10⁶ and glass transition temperatures of 38.0-43.5°C, lower than those obtained without using PNAEI. The investigation by means of FTIR and 1H-NMR techniques revealed that PNAEI was incorporated into the nanoparticles.     

Film Formation from Nanosized Copolymeric Latex Particles: A Photon Transmission Study

The photon transmission technique was used to monitor the evolution of transparency during film formation from nanosized copolymeric latex particles. The latex films were prepared from poly(methyl methacrylate-co-butyl methacrylate) (P(MMA-co-BMA)) particles which were produced by microemulsion polymerization. These films were annealed at elevated temperatures in various time intervals above the glass transition temperature (T(g)) of P(MMA-co-BMA). It is observed that the transmitted photon intensity (I(tr)) from these films increased as the annealing temperature increased. There are three different film formation stages. These stages are explained by the void closure, healing, and interdiffusion processes, respectively. The activation energies for viscous flow (DeltaH approximately 16 kcal/mol), minor chains (DeltaE(H) approximately 27 kcal/mol), and backbone motion (Delta E(b) approximately 132 kcal/mol) were obtained using various models. Void closure (tau(v), T(v)) and healing points (tau(H), T(H)) were determined. Using the time-temperature pairs, void closure and healing activation energies were measured and found to be 21 and 30 kcal/mol, respectively. Copyright 2001 Academic Press.     

Binuclear and mononuclear cobalt(II), nickel(II) and copper(II) complexes of 4,4′-bis(alkylaminoisonitrosoacetyl)diphenyl-methane derivatives

4,4-Bis(chloroacetyl)diphenylmethane has been prepared from ClCH₂COCl and Ph₂CH₂. 4,4-Methylenebis(phenylglyoxylohydroximoyl chloride has also been obtained. Four new substituted 4,4-bis(alkylaminoisonitrosoacetyl)diphenylmethanes (ligands) have been prepared from 4,4-methylenebis(phenylglyoxylohydroximoyl chloride) and the corresponding amines. The Ni^II, Cu^II and Co^II complexes of these ligands were prepared and their structures were identified using AAS, i.r., ¹H-n.m.r. spectral data, elemental analyses and magnetic susceptibility measurements.