Structural,Morphological and Optical Properties of Well-Ordered CdO Nanostructures Synthesized by Easy-Economical Chemical Bath Deposition Technique

In this Study, Cadmium Oxide (CdO) nanostructures were synthesized by using Chemical Bath Deposition Technique. The synthesized process was carried out at room temperature. The structural and optical properties of nanostructures was characterized by XRD, SEM and UV-Vis techniques. As a result, the CdO nanostructures are oriented along (111) plane of cubic crystal structure. The morphology of CdO nanostructures showed interconnected prism-like and cauliflower-type cluster nanostructure. The UV results of this structures with high absorbtion coefficient are observed to be in accordance with the CdO nanoparticles.     

On the complex factorization of the Lucas sequence

In this paper, firstly we present a connection between determinants of tridiagonal matrices and the Lucas sequence. Secondly, we obtain the complex factorization of Lucas sequence by considering how the Lucas sequence can be connected to Chebyshev polynomials by determinants of a sequence of matrices.     

On the influence of boundary conditions on the modal properties of a base frame

Supports of turbomachineries can be designed as base frames, which are constructions of steel-plates. One of the most important design requirements of the turbomachinery system is to avoid of natural frequencies in the operating speed range. Thus, a rotor dynamics analysis (see e.g. [1]), which is usually carried out using transfer matrix methods or finite element methods has to take the dynamic stiffness of the base frame into account. However, there are several problems to identify this complex and frequency dependent parameter, for example the localization of excitation or measurement responses and the difficulty of the support of base frames, e.g jack screws. In this article the support of a test base frames is analyzed by modal analysis experimentally. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Weakly automorphism invariant modules and essential tightness

While a module is pseudo-injective if and only if it is automorphism-invariant, it was not known whether automorphism-invariant modules are tight. It is shown that weakly automorphism-invariant modules are precisely essentially tight. We give various examples of weakly automorphism-invariant and essentially tight modules and study their properties. Some particular results: (1) R is a semiprime right and left Goldie ring if and only if every right (left) ideal is weakly injective if and only if every right (left) ideal is weakly automorphism invariant; (2) R is a CEP-ring if and only if R is right artinian and every indecomposable projective right R-module is uniform and essentially R-tight.     

A Simulation Study on the Determination of the Best Investment Plan for Istanbul Seaport

The article involves an account of a simulation study undertaken to determine the best investment plan and the best investment year for Istanbul seaport. The best investment plan is defined to be the alternative with minimum total cost, which is the sum of investment costs and ship waiting time cost discounted to their present value. Investment alternatives considered consist of the construction of a new port, construction of a new berth for the existing port and construction of hinterland warehouses. An attempt has been made to determine the best quay length, number of cranes and warehouse capacity for the new port. The sensitivity of the best investment plan and year to different demand levels is studied. Next, another experiment is conducted to determine the effect of increased efficiency on investment requirements. In all experiments total cost is determined with three levels of inflation and three levels of devaluation rates using three levels of discount factors.     

Über Metallkomplexe der Heteroarylformazane

Two new heteroarylformazans with two complex forming carboxy groups in the ortho position relative to the formazan chain have been synthesized. These compounds form complexes with uranyl, cobalt and nickel ions. The ratio metal/formazan of these complexes has been investigated.

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Teil der Dissertation,. Kaban, Univ. Istanbul 1975.     

Use of Benzoylthiourea Immobilized on Silica Gel for Separation and Preconcentration of Uranium(VI)

Benzoylthiourea immobilized on silica gel was prepared by two-step post-synthesis modification. The capacity of the chelating silica gel, which was characterized by FTIR, was 3.21 mmol · g⁻¹. The separation and enrichment of uranium(VI) from solutions was investigated. Effective extraction conditions were optimized in both batch and column methods prior to determination by spectrophotometry using arsenazo(III). The optimum pH range for quantitative adsorption is 4–7. Quantitative recovery of U(VI) was achieved by stripping with 0.1 mol · L⁻¹ HCl. The sorption capacity of modified silica gel was 0.85 mmol · g⁻¹ uranium(VI). Recovery of U(VI) was 99.1 ± 2.3% with a detection limit of 2 μg · L⁻¹. The preconcentration factor was 250, and the relative standard deviation was 1.53% for a 1 μg · L⁻¹ U(VI) solution. The method was used for the determination of uranium in synthetic samples and a soil sample.     

Rheological and dynamic-mechanical behavior of carbon nanotube/vinyl ester-polyester suspensions and their nanocomposites

Rheological properties of vinyl ester-polyester resin suspensions containing various amounts (0.05, 0.1 and 0.3 wt.%) of multi walled carbon nanotubes (MWCNT) with and without amine functional groups (-NH₂) were investigated by utilization of oscillatory rheometer with parallel plate geometry. Dispersion of corresponding carbon nanotubes within the resin blend was accomplished employing high shear mixing technique (3-roll milling). Based on the dynamic viscoelastic measurements, it was observed that at 0.3 wt.% of CNT loadings, storage modulus (G′) values of suspensions containing MWCNTs and MWCNT-NH₂ exhibited frequency-independent pseudo solid like behavior especially at lower frequencies. Moreover, the loss modulus (G″) values of the resin suspensions with respect to frequency were observed to increase with an increase in contents of CNTs within the resin blend. In addition, steady shear viscosity measurements implied that at each given loading rate, the resin suspensions demonstrated shear thinning behavior regardless of amine functional groups, while the neat resin blend was almost the Newtonian fluid. Furthermore, dynamic mechanical behavior of the nanocomposites achieved by polymerizing the resin blend suspensions with MWCNTs and MWCNT-NH₂ was investigated through dynamic mechanical thermal analyzer (DMTA). It was revealed that storage modulus (E′) and the loss modulus (E″) values of the resulting nanocomposites increased with regard to carbon nanotubes incorporated into the resin blend. In addition, at each given loading rate, nanocomposites containing MWCNT-NH₂ possessed larger loss and storage modulus values as well as higher glass transition temperatures (T_g) as compared to those with MWCNTs. These findings were attributed to evidences for contribution of amine functional groups to chemical interactions at the interface between CNTs and the resin blend matrix. Transmission electron microscopy (TEM) studies performed on the cured resin samples approved that the dispersion state of carbon nanotubes with and without amine functional groups within the matrix resin blend was adequate. This implies that 3-roll milling process described herein is very appropriate technique for blending of carbon nanotubes with a liquid thermoset resin to manufacture nanocomposites with enhanced final properties.