Application of Nonlinear Regression Analysis for Methyl Violet (MV) Dye Adsorption from Solutions onto Illite Clay

Dyes are toxic chemicals and the main source of color pollution in the textile wastewaters. Therefore, the use of illite clay as an adsorbent to remove methyl violet dye from solutions was investigated in this study. Equilibrium experiments were carried out in batch mode as a function of temperature, ionic strength, and pH. The equilibrium was attained within 24 hours. The capacity of illite clay increased when pH, temperature, and ionic strength were raised. Four adsorption isotherm models, viz, the Langmuir, Freundlich, Khan, and Sips, were used to analyze the equilibrium data. The nonlinear optimization technique was used to fit the data to the isotherm models, and for this purpose five error functions were used. The equilibrium data could be explained by the Sips isotherm model, and among the entire error equations generally the HYBRID error function provided the lowest sum of the normalized error values. Thermodynamic parameters indicated that dye adsorption had endothermic and unspontaneous nature. Also, the positive enthalpy change indicated that dye uptake occurred by physical binding. The maximum dye capacity of illite was found as 159.95 mg g^?1 at 60°C. High dye capacity exposed that illite would be used effectively in cationic dye removal.     

A Directly Fused Subporphyrin Dimer with a Wavelike Structure

[Ni(cod)₂]‐mediated intramolecular reductive coupling of β–β′ linked meso,meso′‐dibromosubporphyrin dimer gave the anti‐isomer of meso–meso′, β–β′ doubly linked subporphyrin dimer as the first example of a fused subporphyrin dimer. The fused dimer 3 _anti displays an wavelike coplanar structure, a perturbed and red‐shifted absorption spectrum, reversible redox behaviors with a decreased electrochemical HOMO–LUMO band gap, and a short S₁‐state lifetime owing to the delocalized π‐electronic network.     

Synthesis of (3,6-dihydro-2H-pyran-2-yl)phosphonate derivatives and investigation of catalyst effect on frontier molecular orbitals using DFT method

Hetero Diels-Alder (HDA) reactions between 2,3-dimethyl-1,3-butadiene and diethyl ester of aroyl phosphonates catalyzed by AlCl₃ to afford (3,6-dihydro-2H-pyran-2-yl) phosphonate derivatives were investigated. Aroyl phosphonates with electron-withdrawing groups generally resulted in better isolated chemical yields. A stoichiometric amount of AlCl₃ rather than a catalytic amount was necessary to activate the cycloaddition reaction. The amount of AlCl₃ catalyst and its effect on LUMO of ethyl ester benzoyl phosphonate were also investigated by performing density functional theory (DFT) (B97D/6-31+G(d,p)) computations in dichloromethane. An increased loading of AlCl₃ induced a considerable decrease in the LUMO energy of ethyl ester of benzoyl phosphonate. The computed Gibbs free activation energy is 17.03 kcal/mol in DCM at 0°C using the same computational level.     

Annual variations of the elemental concentrations of PM10 in ambient air of Nagoya City as determined by ICP-AES and ICP-MS.

PM10 samples were collected at an urban site of Nagoya City during September, 2003, to August, 2004, and annual variations of the concentrations of the elements in PM10 samples were examined by inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). The annual concentration variations of ca. 30 elements in ambient air were in the range from sub-ng m(-3) to several microg m(-3). From an evaluation by the enrichment factors of the elements, elements such as Al, Ca, Fe, Mg, Ti, Mn, Ba, Sr, Ce, La, Nd, Co, Cs, and Pr, in PM10 samples were found to have originated mostly from natural sources, while the elements such as S, Zn, Pb, Cu, Ni, Sb, Sn, Cd, Bi, W, Tl, and In originated from anthropogenic emission sources. Furthermore, in seasonal variations of the elemental concentrations of PM10 samples in ambient air, the elements originated mostly from natural sources provided significantly high concentrations in spring during the "Kosa" period (the dust season from March to May). On the other hand, the elements mainly from anthropogenic emission sources provided relatively higher concentrations in autumn and winter, which may be explained by the fact that the urban atmospheric structure is stabilized by the temperature-inversion layer formed over the city in those seasons. In addition, all of the elements provided significantly low concentrations in the summer, due to the dilution effect of the oceanic winds as well as due to the convection of air mass up to the high levels.     

Iron hydroxide nanoparticles coated with poly(ethylene glycol)-poly(aspartic acid) block copolymer as novel magnetic resonance contrast agents for in vivo cancer imaging

PEG-coated β-FeOOH nanoparticles were prepared through electrostatic complex formation of iron oxide nanoparticles with poly(ethylene glycol)-poly(aspartic acid) block copolymer [PEG-P(Asp)] in distilled water. By dynamic light scattering (DLS) measurement, the nanopaticle size was determined to be 70 nm with narrow distribution. The FT-IR and zeta potential experimental results proved that PEG-PAsp molecules bound to the surface of the iron oxide nanoparticles via the coordination between the carboxylic acid residues in the PAsp segment of the block copolymer and the surface Fe of the β-FeOOH nanoparticles. The PEG-coated nanoparticles revealed excellent solubility and stability in aqueous solution as well as in physiological saline. In vivo MRI experiments on tumor-bearing mice demonstrated that the PEG-coated nanoparticles prepared by the current approach achieved an appreciable accumulation into solid tumor, suggesting their potential utility as tumor-selective MRI contrast agents.     

Supramolecular control of unwinding and rewinding of a double helix of oligoresorcinol using cyclodextrin/adamantane system

The double helix of the oligoresorcinol nonamer formed in water was unwound by beta-cyclodextrin (beta-CD), and the resulting single strands of the nonamer threaded the beta-CD to form a twisted [3]-pseudorotaxane with a controlled helicity. Upon the addition of an adamantane, the single strand of the oligoresorcinol nonamer was expelled out of the beta-CD wheels, thus regenerating the double helix. This supramolecularly controlled, reversible unwinding and rewinding of the double helix is unique and can be readily monitored by spectroscopic techniques.     

High sequence-coverage detection of proteolytic peptides using a bis(terpyridine)ruthenium(II) complex

The use of a bis(terpyridine)ruthenium(ii) complex for peptide labeling (Ru-CO labeling) supplied high intensity peaks in mass spectrometry (MS) analysis that overcame the contribution of protonation or sodiated adduction to peptides. Ru-CO-labeled insulin A- and B-chains were detected simultaneously in comparable peak abundance by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The mass spectra of chymotryptic peptide fragments of Ru-CO-labeled insulin also simultaneously indicated both N-terminal fragment ions, and amino acid sequences were determined easily by matrix-assisted laser desorption/ionization post-source-decay (MALDI-PSD). The sensitivity of detecting Ru-CO-labeled peptide fragment ions was not dependent on the length or the sequences of the peptides. The Ru-CO labeling method was applied to tryptic myoglobin fragments. The method indicated that each fragment ion is detected nearly equal in abundance and enabled the desired fragment ions to be distinguished from matrix clusters or their in-source fragments in lower mass regions. The desired fragment ions can be found in the mass region higher than 670.70 (= Ru-CO). This method provided a high sequence coverage (96%) by peptide mass fingerprinting (PMF). Application of this method to a protein mixture (myoglobin, lysozyme and ubiquitin) successfully achieved high sequence-coverage characterization (>90%) of these proteins simultaneously.     

Magnetic properties of synthetic libethenite Cu2PO4OH: a new spin-gap system

Synthetic mineral libethenite Cu(2)PO(4)OH was prepared by the hydrothermal method, and its structure at 200 K was refined by single-crystal X-ray diffraction. The structure of Cu(2)PO(4)OH is built up from Cu2(2)O(6)(OH)2 dimers of edge-sharing Cu2O(4)(OH) trigonal bipyramids and [Cu1(2)O(6)(OH)(2)] proportional chains of edge-sharing Cu1O(4)(OH)(2) octahedra. Magnetic properties of Cu(2)PO(4)OH were investigated by magnetic susceptibility, magnetization, and specific heat measurements. Cu(2)PO(4)OH is a spin-gap system with a spin gap of about 139 K. It was shown by spin dimer analysis that, to a first approximation, the magnetic structure of Cu(2)PO(4)OH is described by an isolated square-spin cluster model defined by the Cu1-O-Cu2 superexchange J with Cu1...Cu2 = 3.429 A. The fitting analysis of the magnetic susceptibility data with a square-spin cluster model results in J/k(B) = 138 K. Specific heat data show that Cu(2)PO(4)OH does not undergo a long-range magnetic ordering down to 1.8 K. We also report vibrational properties studied with Raman spectroscopy and the thermal stability of Cu(2)PO(4)OH.     

Electrochemical,Spectroelectrochemical, and Electrocatalytic Dioxygen Reducing Properties of Peripheral Tetra-2,6-dimethoxyphenoxy Substituted Phthalocyanines

By using of peripherally tetrakis-2,6-dimethoxyphenoxy substituted Co(II), Fe(III), and Mn(III) phthalocyanines was observed to extend the redox richness of the phthalocyanine ring with the addition of reversible metal-based electron transfer couples to the phthalocyanine ring-based electron transfer processes in solution. The emergence of highly steady anionic and cationic redox species with clear spectral and colour changes both in solution and in the film during in situ spectroelectrochemical and in situ electrocolorimetric measurements pointed out their applicability as electrochromic materials. Furthermore, the phthalocyanine complexes demonstrated strong interaction with dioxygen and thus, high electrocatalytic enforcement for its reduction.     

Evaluation on dye removal capability of didodecyldimethylammonium-bentonite from aqueous solutions

The removal efficiency of Reactive Blue 19 (RB19) by using surfactant-modified bentonite (MB) from aqueous solutions, and also textile wastewater samples was examined. Natural bentonite (NB) was firstly modified with didodecyldimethylammonium bromide (DDDAB) in order to increase the removal capacity of bentonite. MB was then characterized by Fourier Transformed Infrared Spectrophotometer (FTIR), x-ray diffractometry (XRD), x-ray fluorescence (XRF), Scanning Electron Microscope (SEM)/EDX, zeta potential, elemental, and thermal analysis techniques. The high adsorption capacity of MB was 407.7?mg g^?1 at pH?=?1.5 and 20^°C. The adsorption of Reactive Blue 19 onto MB agreed with the pseudo-second-order kinetic and Langmuir isotherm models.