NATURAL ZEOLITES IN AIR DRYING

The local clinoptilolite from Bigadis region in Turkiye, was used for air drying in packed column. The effective diffusion coefficient of water in natural zeolite was found as 5×10^-10 m² s^-1 from isothermal uptake measurements. Effects of packing height and airvelocity on breakthrough curves were studied.     

Modeling of ferrofluid magnetic actuation with dynamic magnetic fields in small channels

One of the most important and promising research areas in biomedical and micropumping applications is magnetic actuation of ferrofluids with dynamic magnetic fields. For ensuring the use of ferrofluids in various applications in engineering fields, their flows generated by magnetic fields should be extensively investigated and simulated. In this study, simulations of ferrofluid actuation with dynamic magnetic fields were performed by modeling it using the COMSOL Multiphysics software, and iron oxide nanoparticle-based ferrofluids at different angles of rotating magnets were considered to provide insight into ferrofluid flow in small channels. Ferrofluid flows were modeled at different magnetic flux densities provided by rotating magnets, and velocity profiles inside the channel were analyzed. It was shown that ferrofluid actuation can be considered as a futuristic micropumping alternative, simulation results matched well with the experimental results of previous work, and the established model could serve as a tool to analyze ferrofluid flows generated by dynamic magnetic fields. The results of the model show that flow rates up to 100 µl/s can be reached at a rotation angle of 30° by using dynamic magnetic fields. Various applications including biomedical applications might be envisaged.     

Photochemically masked benzophenone: Photoinitiated free radical polymerization by using benzodioxinone

A new photoinitiating system for free radical polymerization of methyl methacrylate (MMA) is reported. This system consists of benzodioxinone and hydrogen donors such as triethylamine (TEA), N,N-dimethyl ethanol amine (DMEA) and tetrahydrofuran (THF). A feasible mechanism involves photoinduced formation of benzophenone from benzodioxinone and subsequent hydrogen abstraction of photoexcited benzophenone from hydrogen donors to yield radicals capable of initiating polymerization of MMA.     

Corrosion inhibition of aluminum by novel phthalocyanines in hydrochloric acid solution

The corrosion inhibition characteristics of quaternized 1,(4)-tetrakis[(2-mercapto)pyridine]phthalocyanine (I) and 2,3-octakis[(2-mercapto)pyridine] phthalocyanine (II) on aluminum in 0.1 M HCl solution has been studied by means of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The maximum inhibition efficiency was obtained for compound I with two-electrochemical techniques applied. Langmuir isotherm fits well the experimental data. The inhibition efficiency increases with increase in the phthalocyanine concentration, but decreases with an increase in temperature. The phthalocyanines act predominately as cathodic inhibitor.     

pH‐ and temperature‐induced release of doxorubicin from multilayers of poly(2‐isopropyl‐2‐oxazoline) and tannic acid

We present a simple strategy to prepare doxorubicin (DOX) containing hydrogen‐bonded films of poly(2‐isopropyl‐2‐oxazoline) (PIPOX) and tannic acid (TA) which release DOX in acidic conditions while releasing a minimal amount of DOX at physiological pH. Water soluble complexes of TA and DOX (TA ? DOX) were prepared prior to film construction. PIPOX and TA ? DOX were deposited at the surface at pH 6.5 using the layer‐by‐layer (LbL) technique. We found that multilayers released a minimal amount of DOX at physiological pH due to further ionization of TA with increasing pH and enhanced electrostatic interactions between TA and DOX. In contrast, pH‐induced release of DOX was observed in moderately acidic conditions due to protonation of TA as the acidity increased and electrostatic interactions between TA and DOX decreased. Moreover, we found that raising the temperature from 25 °C to 37.5 °C increased the amount of DOX released from the surface. This can be rationalized with the conformational changes within the multilayers correlated with the lower critical solution temperature behaviour of PIPOX and increased kinetic energy of DOX molecules. Considering the acidic nature of tumour tissues and important biological properties of PIPOX and TA, these multilayers are promising for pH‐ and temperature‐triggered release of DOX from surfaces. © 2017 Society of Chemical Industry     

Macromolecular design and application using Mn2(CO)10‐based visible light photoinitiating systems

The environmentally friendly Mn₂(CO)₁₀‐based visible light photoinitiating system is a powerful method for the preparation of linear and crosslinked polymeric structures. From a practical point of view, the most important feature of this initiating system is its optical characteristics in the visible range with high quantum yield and good solubility properties. This photoinitiating system is applicable for a variety of monomers that can be polymerized via either radical or cationic mechanisms. Various complex macromolecular structures such as telechelic polymers, block and graft copolymers, polymer networks and surface modifications can be simply prepared by using halogenated precursors. This photoinitiating system is also combined with controlled radical polymerization techniques providing a mild and efficient method for polymer synthesis. © 2016 Society of Chemical Industry     

Reduction of Cu(II) by photochemically generated phosphonyl radicals to generate Cu(I) as catalyst for atom transfer radical polymerization and azide-alkyne cycloaddition click reactions

The photoinduced electron transfer reactions of acylphosphine oxide type photoinitiators with Cu(II)Cl₂/N,N,N′,N′′,N′′-pentamethyldiethylenetriamine complex for both atom transfer radical polymerization and copper catalyzed azide-alkyne cycloaddition processes is investigated by laser flash photolysis. The photolytically generated phosphonyl radicals are effective in reducing Cu(II) salts to Cu(I) with rate constants of ∼2 × 10⁹ M⁻¹ s⁻¹.     

The synthesis and characterization of Cu(II) phthalocyanine bearing peripheral monoazacrown ethers and a spectral investigation of its film forming character

The synthesis, liquid crystalline behavior and self-organizing properties of Cu(II)Pc bearing monoazacrown ether moieties that contain long alkyloxyphenyl N-pivotal groups are described. The Cu(II) phthalocyanine derivative has a hexagonal, columnar structure; optical absorption and vibrational spectroscopy revealed a predominantly co-facial interaction between the chromophores and their orientation parallel to a NaCl surface. It is proposed that such homeotropic alignment is attributable to the ability of the pendant monoazacrown ether groups to coordinate the Na⁺ ions within the NaCl surface.     

Analysis of international debt problem using artificial neural networks and statistical methods

It is known from the scientific researches that artificial neural networks are alternatives of statistical methods such as regression analysis and classification in recent years. Since multi-layer backpropagation neural network models are nonlinear, it is expected that the neural network models should make better classifications and predictions. The studies on this subject support that idea. In this study, a macro-economic problem on rescheduling or non-rescheduling of the countries’ international debts is taken into account. Among the statistical methods, logistic and probit regression, and the different neural network backpropagation algorithms are applied and comparisons are made. Evaluations and suggestions are made depending on the results and different neural network architecture.     

Geostatistical assessment of rock zones for tunneling

Geostatistical assessments can be used for understanding the distribution of regionalized variables (ReVs) in any spatial study. Many researchers have used the theory of ReVs for different modeling purposes such as hydraulics, mining deposits, etc. In this paper, ReV technique is used for understanding the mechanical variation properties of rock zones under sampled and unsampled conditions in sewer tunnels for Istanbul. This study has been carried out for three different rock properties that are compressive strength, rock quality designation (RQD), Schmidt hammer hardness, and one rock cuttability property, net cutting rate. In order to define ReVs distribution, first semivariogram functions are determined and then kriging maps are generated for identifying the regional dependence. Furthermore, it is possible to make estimations for every point within the study area, and prepare maps for the interpretation of regional features of the ReV concerned. Net cutting rate is a cuttability property of rock, which can be regionalized and compared with the mechanical properties of rocks. This can be used for predicting the performance of excavator.