Synthesis, electro-spectroelectrochemical characterization and electrocatalytic behavior towards dioxygen reduction of a new water-soluble cobalt phthalocyanine containing naphthoxy-4-sulfonic acid sodium salt

A new water-soluble cobalt phthalocyanine, 2(3), 9(10), 16(17), 23(24)-tetrakis(4-(1-naphthoxy-4-sulfonic acid sodium salt)) phthalocyaninato cobalt(II) NhtCoPc, where Nht indicates naphthoxy-4-sulfonic acid sodium salt, was synthesized and its electro-spectroelectrochemical and electrocatalytic behavior towards oxygen reduction reaction were investigated in details. The complexation reaction was monitored with the UV-vis spectral changes of NhtH₂Pc in methanol solution. The reaction was completed when the main Q-band was observed in maximum intensity. The electrochemical studies showed that the cobalt complex exhibited two reversible one-electron reductions with the corresponding anodic wave and an irreversible oxidation reaction in DMSO solution. These reduction processes were assigned to Co(2+)Pc(2−)/Co(+)Pc(2−) and Co(+)Pc(2−)/Co(+)Pc(3−) couples, respectively. The well-defined UV-vis spectra of the mono-anionic species [NhtCo(+)Pc(2−)]⁻, di-anionic species [NhtCo(+)Pc(3−)]²⁻, and mono-cationic species [NhtCo(3+)Pc(2−)]⁺, were obtained by the applied potentials (E_app = −0.60, −1.40, and 0.70 V, respectively) in a thin-layer cell. NhtCoPc was incorporated into the conductive polyaniline (PAni) films as a dopant-anion during electropolimerization in acid medium, and thus formed the Pt/PAni-NhtCoPc electrode. This modified electrode was characterized by scanning electron microscopy (SEM), as well. The addition of NhtCoPc to the polymerization solution changes markedly the morphology of the films obtained and increases the redox-activity towards oxygen reduction of the PAni film formed compared to those of Pt/PAni and bare platinum electrodes in the same experimental conditions.     

Estimating the uniaxial compressive strength of some clay-bearing rocks selected from Turkey by nonlinear multivariable regression and rule-based fuzzy models

Abstract: Although the use of predictive models in rock engineering and engineering geology is an important issue, some simple and multivariate regression techniques traditionally employed in these areas have recently been challenged by the use of fuzzy inference systems and artificial neural networks. The purpose of this study was to construct some predictive models to estimate the uniaxial compressive strength of some clay-bearing rocks, depending on examination of their slake durability indices and clay contents. For this purpose, the simple and nonlinear multivariable regression techniques and the Mamdani fuzzy algorithm are compared in terms of their accuracy. To increase the accuracy of the Mamdani fuzzy inference system, the weighted if–then rules are extracted. To compare the predictive performances of the models, the statistical performance indices (root mean square error and variance account for) are calculated and the results are discussed. The indices reveal that the fuzzy inference system has a slightly higher prediction capacity than the regression models. The basic reason for the higher performance of the fuzzy inference system is the flexibility of the fuzzy approach.     

A practical procedure for the back analysis of slope failures in closely jointed rock masses

Where closely jointed rock masses are encountered in slopes, failure can occur both through the rock mass, as a result of combination of macro and micro jointing, and through the rock substance. Determination of the strength of this category of rock mass is extraordinarily difficult since the size of representative specimens is too large for laboratory testing. This difficulty can be overcome by using a non-linear rock mass failure criterion or by back analysis of such slopes to estimate the rock mass strength. In this paper, a practical procedure and a computer program are presented for the back determination of shear strength parameters mobilized in slopes cut in closely jointed rock masses which obey a non-linear failure criterion rather than a linear one. The procedure shows that the constants to derive normal stress dependent shear strength parameters of the failed rock masses can be determined by utilizing a main cross-section and without a pre-determined value of rock mass rating (RMR). Trials are made for different RMR_m and RMR_s values corresponding to various possible combinations of the constant m and s, which are used in the Hoek–Brown failure criterion, satisfying the limit equilibrium condition. It is also noted that the procedure provides a quick check for the rock mass rating obtained from the site investigations. The method is used in conjunction with the Bishop's method of analysis based on circular slip surfaces. The procedure outlined in this paper has also been satisfactorily applied to documented slope failure case histories in three open pit mines in Turkey.     

Liquefaction potential at Izmit Bay: comparison of predicted and observed soil liquefaction during the Kocaeli earthquake

The 1999 Kocaeli earthquake resulted in large-scale damage to structures and a death toll of more than 20,000. Numerous liquefaction and associated ground deformations caused by the earthquake were particularly observed along the southern coasts of Izmit Bay and Sapanca Lake, as well as the city of Adapazari. The paper discusses the soil liquefaction and lateral spreading along the southern coast of Izmit Bay. A microzonation map was created using the data from liquefaction susceptibility analyses and a liquefaction severity index. The predicted liquefiable zones showed good agreement with site observations. The assessment suggests that the amount of liquefaction-susceptible layers in the soil profile reduces away from the coastal zone.      

Estimating the uniaxial compressive strength of a volcanic bimrock

Preparation of the standard sized cores from geological mixtures or fragmented rocks such as mélanges, fault rocks, coarse pyroclastic rocks, breccias and sheared serpentinites is often extremely difficult. Therefore, determination of the mechanical parameters such as cohesion, friction angle and UCS is extraordinarily difficult for these types of rocks. This paper presents the results of studies using Ankara Agglomerate to develop an empirical approach for the determination of the UCS for a volcaniclastic mixture of strong andesite blocks within weak tuff matrix, formed from the aggregation of volcanically exploded rock debris mixed with ash fall (tuff), i.e. a bock-in-matrix rock or ‘bimrock’. The uniaxial compressive strength of a volcanic bimrock can be predicted using the conceptual approach within as-yet poorly understood error limits. Therefore, the approach introduced is open to improvement depending on the number of data and cases including different type of bimrocks.     

A Robust Electroactive n‐Dopable Aromatic Polyketone

A new n‐dopable polyketone, poly[(5‐(2,5‐dihexyl‐4‐(thiophen‐2‐yl)phenyl)thiophen‐2‐yl)(4‐ketophenyl)methanone] (PTK), is synthesized via Friedel–Crafts acylation. Though insulating in the neutral state, PTK becomes conductive upon electrochemical reduction. The stable, two‐electron, fully reversible reduction is probed spectroelectrochemically and via in‐situ conductivity measurements.     

Novel poly(orthosilicate)s based on linear aliphatic diols: Synthesis,characterization, and swelling properties

Condensation reactions between tetraethyl orthosilicate and linear aliphatic diol monomers at moderately high temperatures in proper stoichiometric ratios gave crosslinked poly(orthosilicate)s. The synthesized crosslinked polymers were found to be insoluble in common organic solvents, such as tetrahydrofuran, dichloromethane, benzene, and acetone, but did show swelling abilities in these solvents. All of the crosslinked polymers had moderate thermal stability and good, regenerable solvent uptake abilities. The synthesized polymers have been characterized by Fourier transform infrared spectroscopy solid‐state ¹³C‐ and ²⁹Si‐NMR, thermogravimetric analysis, differential scanning calorimetry methods, and elemental analysis. In this report, the synthesis characterization, and swelling properties of crosslinked poly(orthosilicate)s for environmental removal and recovery of organic solvents are presented. The effect of the length of the aliphatic diol monomers on the properties of the synthesized polymers was also examined. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

The effects of deposition parameters on surface morphology and crystallographic orientation of electroless Ni-B coatings

Electroless Ni-B coatings were deposited on AISI 304 stainless steels by electroless deposition method, which was performed for nine different test conditions at various levels of temperature, concentration of NaBH₄, concentration of NiCl₂, and time, using the Taguchi L₉(3⁴) experimental method. The effects of deposition parameters on the crystallographic orientation of electroless Ni-B coatings were investigated using SEM and XRD equipment. SEM analysis revealed that the Ni-B coatings developed six types (pea-like, maize-like, primary nodular, blackberry-like or grapes-like, broccoli-like, and cauliflower-like) of morphological structures depending on the deposition parameters. XRD results also showed that these structures exhibited different levels of amorphous character. The concentration of NaBH₄ had the most dominant effect on the morphological and crystallographic development of electroless Ni-B coatings.