Design details and characterization of all digital closed-loop interferometric fiber optic gyroscope with superluminescent light emitting diode

This paper describes the design details and the characterization of an all digital closed-loop (ADCL) interferometric fiber optic gyroscope (IFOG) Prototype with sine wave biasing modulation and SLED emiting at 1288.9 nm, constructed in TUBITAK UME. Electronic feedback section of ADCL-IFOG is composed of 16 bit AD7714YN ADC, 14 bit-LTC1667CG DAC, fully controlled and synchronized by 89C51 microcontroller. The averaged sensitivity of the ADCL-IFOG prototype in unit of error voltage applied to the phase modulator was calculated as 132.65 μV/(°/h) which equals to a scale factor of 7.53888 (°/h)/mV with a standard deviation of 0.85% for a range of 1–15270 (°/h) rotation rate, corresponding to a range of Sagnac phase shifts varying from 0.00115 to 17.57448 (°). The maximum peak to peak noise and the bias stability of the prototype were determined as 4.97 and 1.48 (°/h) at 23.0°C, respectively. The variation of the noise and bias stability on a temperature range of 23.0–42.0°C was observed.     

Statistical regression and artificial neural network analyses of impinging jet experiments

The purpose of this paper is to focus on the experimentally obtained results of impinging jet applications by the help of two different analysis methods. Circular round pipes (D = 7.9, 10.8, 13.8 and 23.1 mm) have been used as the impinging jets. The heat transfer is calculated with Nusselt number (Nu). The variable parameters are the dimensionless jet-to-impingement plate distance (z/D), Reynolds number (Re) and dimensionless temperature measurement points on the heated surface (x/L, y/L). Some important analysis methods such as artificial neural network (ANN), statistical regression, and uncertainty analysis are applied to the obtained data. It is shown that the ANN application is not simply a classification analysis; it is actually an application of the convergence of functions. As a result, by considering random data, 4.57% convergence level is obtained regarding the pipe diameter. The software STATISTICA 5.0 is used to estimate new empirical correlations nonlinearly. The smallest regression coefficient for the correlations is 0.87, while the highest value is 0.99. The result of the uncertainty analyses showed that the total uncertainties are in the agreeable range; 8% for Nu, and 2.89% for Re. Dr. Nevin Celik is a Post Doctoral Fellowship in University of Minnesota since August 2007.     

Electroinitiated Cationic Copolymerization of Styrene and 4-Methoxystyrene

The copolymerization of styrene and 4-methoxystyrene by constant potential electrolysis in 1,2-dichloroethane was achieved at three different potentials. Amounts of the monomers in the resulting copolymers were found to be potential-dependent. The effect of polymerization potential on copolymer composition was also found to be related to anodic peak potentials (E_p,a) of the monomers.

Monomer reactivity ratios were found with the integrated Lewis-Mayo equation.     

Structural,Spectroscopic, Antimicrobial Activity and DFT Studies on 4-Methyl-<Emphasis Type="Italic">N</Emphasis>-(4-methylphenylsulfonyl)-<Emphasis Type="Italic">N</Emphasis>-phenylbenzenesulfonamide

This study reports the structural characterization of a disulfonimide derivative, 4-methyl-N-(4-methylphenylsulfonyl)-N-phenylbenzenesulfonamide (MPBSA), using spectroscopic and quantum chemical methods. The molecule was characterized with FT-IR, ¹H ¹³C NMR and UV-Vis spectroscopies. Quantum chemical calculations of molecular geometry, vibrational wavenumbers and gauge including atomic orbital (GIAO) ¹H and ¹³C-NMR chemical shifts of the compound were carried out by using density functional method (DFT) at B3LYP/6?311++G(d,p) level of theory. Electronic absorption spectra of the compound have been computed using the time-dependent density functional theory (TD-DFT) method at the same level. A satisfactory consistency between the experimental and theoretical findings was obtained. The antimicrobial activity screening of the compound was performed on some bacteria and fungus species using microdilution method. The results showed that the title molecule have noteworthy antibacterial and antifungal activities.     

Metal adsorption properties of multi-functional PAMAM dendrimer based gels

Metal adsorption studies are getting important and there are many functional adsorbents developed recently. Here, we report the synthesis of multifunctional PAMAM G2 (polyamidoamine) possessing methacryl, amine, hydroxyl and phosphonate groups used in free radical curing gel formulations. UV curable gel is conducted in the presence of acrylamide, bisacrylamide, and polyethylene glycol diacrylate. Adsorption study of the resulting novel sorbents (gels) are carried out with a series of metals. Through a comprehensive study, structure–property relationship of the series gels is conducted by using different amount of amine, hydroxyl, and/or phosphonate ester groups on the PAMAM G2. Selected metals are Cr³⁺, Fe³⁺, Ni²⁺, Cu²⁺, Ag⁺, and Cd²⁺ within a series of hard, intermediate, and soft ionic species. Adsorption study is carried out in pure water environment at neutral pH. Metal ions removal percentages and adsorption capacities of gel adsorbents are calculated by using atomic absorption spectroscopy. There is relationship between the overall functional groups presence in gel formulation and swelling densities for removing the metal ions. Introducing dendrimer into the gel formulation enhanced the metal ions adsorption against to Bare GEL formulation which do not possess dendrimer units. Consequently, the maximum removal efficiency has been obtained for Cr³⁺ and Fe³⁺.     

Cooperative Network Formation via Two-Colour Light-Activated λ-Orthogonal Chromophores

Independently addressing photoreactive sites within one molecule with two colours of light is a formidable challenge. Here, we combine two sequence independent λ-orthogonal chromophores in one heterotelechelic dilinker molecule, to exploit their disparate reactivity utilizing the same reaction partner, a maleimide-containing polymer. We demonstrate that polymer network formation only proceeds if two colours of light are employed. Upon single colour irradiation, linker-decorated post-functionalized polymers are generated at either wavelength and in either sequence. Network formation, however, is only achieved by sequential or simultaneous two colour irradiation. The herein introduced photoreactive system demonstrates the power of wavelength orthogonal chemistry in macromolecular synthesis.