Solid-state vibrational spectroscopy: Part 11. An infrared and raman vibrational spectroscopic study of metal(II) halide aniline complexes

Infrared (4000?200 cm^?1) and Raman (3500?50 cm^?1) spectra are reported for metal(II) halide aniline complexes of the following stoichiometries: (MX₂an₂) (M  Co, Ni or Hg, X  Cl; M  Mn, X  Cl or Br; M  Zn or Cd, X  Cl, Br or I); (MX₂an₃) (M  Mn, X  Cl or Br; M  Ni, X  Cl); (CdCl₂an) and an assignment is proposed for all the observed bands. Low-temperature (83 K) IR spectra are also reported and it is noted that whilst the aniline ring and CH mode values are virtually insensitive to temperature, the NH₂ rocking and metal-ligand stretching mode values increase with decreasing temperature, whilst the NH₂ stretching mode values decrease with decreasing temperature.     

The two‐dimensional coordination polymer poly[[bis(3‐methyl­pyridine)­cadmium(II)]‐tetra‐μ‐cyano‐nickel(II)]

The title complex, [CdNi(CN)₄(C₆H₇N)₂]_n, adopts a slightly distorted octahedral geometry around the Cd centre. Four cyanide N atoms occupy the equatorial coordination sites around the Cd centre. The structure consists of corrugated and cyanide‐bridged polymeric networks made up of tetracyano­nickelate ions coordinated to cadmium, with the Ni ion coordinated by four cyanide ligands in a square‐planar arrangement. The Cd and Ni atoms occupy special positions of 2/m site symmetry. The 3‐methyl­pyridine group, except for two methyl H atoms, lies on a crystallographic mirror plane. The 3‐methyl­pyridine molecules, bound to cadmium in trans positions, are located on both sides of the network. The bonding in the networks occurs because of a departure of the Ni—C—N—Cd sequence of atoms from linearity at the C and N atoms.     

Network growth with preferential attachment for high indegree and low outdegree

We study the growth of a directed transportation network, such as a food web, in which links carry resources. We propose a growth process in which new nodes (or species) preferentially attach to existing nodes with high indegree (in food-web language, number of prey) and low outdegree (or number of predators). This scheme, which we call inverse preferential attachment, is intended to maximize the amount of resources available to each new node. We show that the outdegree (predator) distribution decays at least exponentially fast for large outdegree and is continuously tunable between an exponential distribution and a delta function. The indegree (prey) distribution is poissonian in the large-network limit.     

Polaronic effects in a Gaussian quantum dot

The problem of an electron interacting with longitudinal-optical (LO) phonons is investigated in an N$N$-dimensional quantum dot with symmetric Gaussian confinement in all directions using the Rayleigh–Schrödinger perturbation theory, a variant of the canonical transformation method of Lee–Low–Pines, and the sophisticated apparatus of the Feynman–Haken path-integral technique for the entire range of the coupling parameters and the results for N=2$N=2$ and N=3$N=3$ are obtained as special cases. It is shown that the polaronic effects are quite significant for small dots with deep confining potential well and the parabolic potential is only a poor approximation of the Gaussian confinement. The Feynman–Haken path-integral technique in general gives a good upper bound to the ground state energy for all values of the system parameters and therefore is used as a benchmark for comparison between different methods. It is shown that the perturbation theory yields for the ground state polaron self-energy a simple closed-form analytic expression containing only Gamma functions and in the weak-coupling regime it provides the lowest energy because of an efficient partitioning of the Gaussian potential and the subsequent use of a mean-field kind of treatment. The polarization potential, the polaron radius and the number of virtual phonons in the polaron cloud are obtained using the Lee–Low–Pines–Huybrechts method and their variations with respect to different parameters of the system are discussed.     

FT-IR Spectroscopic Investigation of Adsorption of Pyrimidine on Sepiolite and Montmorillonite from Anatolia

The adsorption of pyrimidine (PM) on natural montmorillonite and sepiolite from Turkey was investigated by FT-IR spectroscopy. The intercalation of PM within montmorillonite has been shown by X-ray diffraction to increase the interlayer spacing. The spectroscopic results indicate that PM molecules adsorbed on sepiolite are coordinated to Lewis acidic centers or surface hydroxyls by H-bonding interaction through one of the pyrimidine ring nitrogen lone pairs. Moreover, some of the adsorbed PM molecules may enter the interior channels of the sepiolite structure and replace zeolitic water. The intercalated PM molecules within montmorillonite are coordinated to exchangeable cations directly or indirectly through water bridges.     

Dynamic Characteristics of a Prototype Arch Dam

This study determines the dynamic characteristics of a prototype arch dam-reservoir-foundation system using Operational Modal Analysis method. Achievement of this purpose involved construction of a prototype arch dam-reservoir-foundation system under laboratory conditions. Ambient vibration tests on the arch dam model identified its natural frequencies, mode shapes, and damping ratios. Natural excitations such as small impact loads vibrated to arch dam. Sensitivity accelerometers which were placed on the dam’s crest collected signals in measurements. Measurements were recorded for empty and full reservoirs. Operational Modal Analysis software processed signals which were collected from the ambient vibration tests. Enhanced Frequency Domain Decomposition technique estimated dynamic characteristics of the dam. Results showed that there was an approximate 20–25% difference between natural frequencies related to empty and full reservoirs.     

Raman micro-spectroscopic analysis of cultured HCT116 colon cancer cells in the presence of roscovitine

Raman micro-spectroscopic analysis of cultured HCT116 colon cancer cells in the presence of roscovitine, [seliciclib, 2-(1-ethyl-2-hydroxy-ethylamino)-6-benzylamino-9-isopropylpurine], a promising drug candidate in cancer therapy, has been performed for the first time. The aim of this study was to investigate modulations in colon cancer cells induced by roscovitine. Raman spectra of the cultured HCT116 colon cancer cells treated with roscovitine at different concentrations (0, 5, 10, 25 and 50 μM) were recorded in the range 400-1850 cm(-1). It was shown that the second derivative profile of the experimental spectrum gives valuable information about the wavenumbers and band widths of the vibrational modes of cell components, and it eliminates the appearance of false peaks arising from incorrect baseline corrections. In samples containing roscovitine, significant spectral changes were observed in the intensities of characteristic protein and DNA bands, which indicate roscovitine-induced apoptosis. Roscovitine-induced apoptosis was also assessed by flow cytometry analysis, and analysis of propidium iodide staining. We observed some modifications in amide I and III bands, which arise from alterations in the secondary structure of cell proteins caused by the presence of roscovitine.     

Some Ricci-flat ($$\alpha ,\beta $$)-metrics

In this paper, we study a special class of Finsler metrics, \((\alpha ,\beta )\)-metrics, defined by \(F=\alpha \phi (\beta /\alpha )\), where \(\alpha \) is a Riemannian metric and \(\beta \) is a 1-form. We find an equation that characterizes Ricci-flat \((\alpha ,\beta )\)-metrics under the condition that the length of \(\beta \) with respect to \(\alpha \) is constant.     

Preparation of novel heterogeneous catalysts by adsorption of a cationic tetrapyrrole on to bentonite: equilibrium, kinetics, and thermodynamics

Abstract  

Adsorption of an octacationic tetrapyrrole, octakis(2-trimethylammoniumethylsulfanyl)porphyrazinatocobalt octaiodide (QCoPz), from aqueous solutions on to negatively charged bentonite was investigated. Effects of temperature, dye concentration, solid concentration, and contact time on adsorption were determined. Zeta potential and ion-release measurements were also used as supporting experiments. Experimental data were analyzed using four adsorption kinetic models; a pseudo second-order kinetic model resulted in better correlation with experimental results than the others. Experimental equilibrium data were analyzed by non-linear regression using five adsorption isotherm models with two, three, or four terms. Free energies, enthalpies, and entropies for the adsorption process were determined. The results indicated that adsorption of QCoPz on bentonite was exothermic and spontaneous in nature. FT-IR spectroscopy of the composite and its desorptive behavior were also investigated to identify the mechanism of adsorption. The novel QCoPz–bentonite composites obtained are likely to be used in “green chemistry” and in a wide range of optical and/or catalytic applications, especially those crucially important in the petroleum and pulp/paper industries for waste water cleaning (destruction of mercaptans, sulfides, phenol, and halogenated aromatics, etc.) and removal of bad odor.