Solvent Effect upon Ion-pair Extraction of Different Sodium Dyes Using Some Crown Ethers

Liquid-liquid extractive-spectrophotometric studies of sodium ion complexes of 18-crown-6(18C6), dibenzo-18-crown-6(DB18C6), 15-crown-5(15C5), and 12-crown-4(12C4) and anionic dyes [4-(2-pyridylazo)-resorcinol monosodium salt monohydrate (PAR), Eriochrom Black T (EBT), and methyl orange (MOR)] and sodium picrate (PICRAT) as the counter ion are described. The overall extraction equilibrium constants for the 1 : 1 complexes of the above crown ethers with sodium dyes between different organic solvents and water have been determined at 25deg;C. They were conducted in various solvent-water systems maintaining an identical initial cation concentration in water, [M0+]w, and macrocyclic ligand concentration in the organic phase, [L0]org}, so that in all extractions [M0+]w : [L0]org ratios were 1 : 1, 1 : 10, 1 : 20, 1 : 50, and 1 : 62.5. An ion association complex formed between the sodium-crown ether complex ion and a dye anion was extracted into the organic solvent, and then the dye concentration of the separated aqueous phase was measured with an ultraviolet-visible spectrophotometer. PAR was the best associated dye with all crown ethers sodium-dyes and the extracted dye occurs as the ion-pair complex. Methylene chloride was found to be better than other extractive solvents used in this study.     

Comparison of the Optoelectronic Performance of Neutral and Cationic Forms of Riboflavin

The riboflavin dye 2,3,4,5-tetra-O-acetyl-1-[3-(6-bromohexyl)-7,8-dimethyl-2,4-dioxo-3,4-dihydrobenzo[g]pteridin-10(2H)-yl]-1-deoxypentitol and its pyridinium salt were synthesized, and studied by absorption and fluorescence spectroscopy in solutions and on thin film states. The first absorption band of riboflavin-pyridinium salt derivative is red-shifted by 10 nm compared to neutral one on film. Cationic riboflavin derivative shows significant wavelength changes on its fluorescence emission spectrum in the excited state depending on the solvent polarity and the electronic environment. The fluorescence quantum yields of cationic riboflavin gave much higher values as compared to that of its neutral form. The fluorescence lifetimes were found to be in the range of 5.5–6.6 ns with mono ? exponential behavior. These dyes possess low-lying HOMO energy levels which are suitable to be able to inject holes to donor polymers so that they can be used as acceptor component in the active layer of bulk heterojunction solar cells (BHJ-SCs). Photovoltaic responses are reported for P3HT:riboflavin active layer wherein the synthesized dyes are used as acceptor component. Also, neutral riboflavin shows greater electron mobility value of 1.3 × 10^?3 cm²/V?s compared to its cationic derivative.     

Gold nanoparticles having dipicolinic acid imprinted nanoshell for Bacillus cereus spores recognition

Taking into account the recognition element for sensors linked to molecular imprinted polymers (MIPs), a proliferation of interest has been witnessed by those who are interested in this subject. Indeed, MIP nanoparticles are theme which recently has come to light in the literature. In this study, we have proposed a novel thiol ligand-capping method with polymerizable methacryloylamidocysteine (MAC) attached to gold nanoparticles, reminiscent of a self-assembled monolayer. Furthermore, a surface shell by synthetic host polymers based on molecular imprinting method for recognition has been reconstructed. In this method, methacryloyl iminodiacetic acid-chrome (MAIDA–Cr(III)) has been used as a new metal-chelating monomer via metal coordination–chelation interactions and dipicolinic acid (DPA) which is the main participant of Bacillus cereus spores has been used as a template. Nanoshell sensors with templates produce a cavity that is selective for DPA. The DPA can simultaneously chelate to Cr(III) metal ion and fit into the shape-selective cavity. Thus, the interaction between Cr(III) ion and free coordination spheres has an effect on the binding ability of the gold nanoparticles nanosensor. The interactions between DPA and MIP particles were studied observing fluorescence measurements. DPA addition caused significant decreases in fluorescence intensity because they induced photoluminescence emission from Au nanoparticles through the specific binding to the recognition sites of the crosslinked nanoshell polymer matrix. The binding affinity of the DPA imprinted nanoparticles has been explored by using the Langmuir and Scatchard methods and the analysis of the quenching results has been performed in terms of the Stern–Volmer equation.     

Diffusion-weighted magnetic resonance imaging in differentiation of postobstructive consolidation from central lung carcinoma

Purpose

To prospectively evaluate diffusion-weighted (DW) magnetic resonance (MR) imaging for differentiation of postobstructive consolidation from centrally located lung carcinomas by using apparent diffusion coefficients (ADCs).

Materials and Methods

An institutional review board approved this study; informed consent was obtained from patients. Forty-nine consecutive patients (3 women, 46 men; mean age, 63.6 years; age range, 42–85 years) with lung carcinoma underwent DW MR imaging. Forty patients had central and nine patients had peripheral lung carcinomas. ADC of each lung carcinoma was calculated from DW MR images obtained with two different b values (0, 1000 s/mm²).In the final study group including 27 patients with central lung carcinoma accompanying distal lung consolidation (mean age, 67.2 years; 3 women, 24 men), ADCs of lung carcinomas were statistically compared among cytologic/histologic types and accompanying postobstructive consolidations. Unpaired t test was used for measurable variables with normal distribution, and Kruskal–Wallis variance analysis and Mann–Whitney U tests were used for the measurable variables without normal distribution.

Results

There was no significant difference between mean ADC values of all types of carcinomas (P=.302) and also between mean ADC values of central (1.91 ± 0.7×10⁻³ mm²/s) and peripheral carcinomas (1.58 ± 0. 6×10⁻³ mm²/s) (P=.224). The mean ADC value for the masses of central lung carcinoma with postobstructive consolidations was 1.83 ± 0.75×10⁻³ mm²/s, and for consolidation was 2.50 ± 0.76×10⁻³ mm²/s. ADC of central carcinoma masses was significantly lower than that of postobstructive consolidations (P=.003).

Conclusions

ADC values of central lung carcinoma masses appear to be lower than accompanying postobstructive consolidations. ADC values could be considered useful as a differentiating parameter among central lung carcinomas and accompanying postobstructive consolidations.     

DX-center energy calculation with quantitative mobility spectrum analysis in n-AlGaAs/GaAs structures with low Al content

Experimental Hall data that were carried out as a function of temperature (60–350 K) and magnetic field (0–1.4 T) were presented for Si-doped low Al content (x=0.14) n–Al_xGa_1−xAs/GaAs heterostructures that were grown by molecular beam epitaxy (MBE). A 2-dimensional electron gas (2DEG) conduction channel and a bulk conduction channel were founded after implementing quantitative mobility spectrum analysis (QMSA) on the magnetic field dependent Hall data. An important decrease in 2DEG carrier density was observed with increasing temperature. The relationship between the bulk carriers and 2DEG carriers was investigated with 1D self consistent Schrödinger–Poisson simulations. The decrement in the 2DEG carrier density was related to the DX-center carrier trapping. With the simulation data that are not included in the effects of DX-centers, 17 meV of effective barrier height between AlGaAs/GaAs layers was found for high temperatures (T>300 K). With the QMSA extracted values that are influenced by DX-centers, 166 meV of the DX-center activation energy value were founded at the same temperatures.     

The neutron-proton pairing and the moments of inertia of the rare earth even-even nuclei

In this study, the possible effect of the neutron-proton pairing interaction in the heavy nuclei has been investigated in the framework of the BCS model by making a simple approximation. This effect has been searched realistically by calculating the moments of inertia of deformed even-even nuclei. Calculations show that the moments of inertia of rare earth nuclei changed dramatically and approached the experimental values.     

IR, Raman and SERS spectra of 2-phenoxymethylbenzothiazole

The FT-IR and FT-Raman spectra of 2-phenoxymethylbenzothiazole were recorded and analyzed. The surface enhanced Raman scattering (SERS) spectrum was recorded in a silver colloid. The vibrational wavenumbers of the compound have been computed using the Hartree–Fock/6-31G* basis and compared with the experimental values. The appearance of the Ag–O stretching mode at 237 cm⁻¹ in the SERS spectrum along with theoretically calculated atomic charge density, leads us to suggest that the molecule is adsorbed through the oxygen atom with the molecular plane tilted on the colloidal silver surface. The direction of charge transfer contribution to SERS has been discussed from the frontier orbital theory.     

Dynamic modelling and simulation of a hot strip finishing mill

Hot rolling is an essential industrial process in the production of sheet steel, a widely used product in manufacturing and construction. A finishing mill performs a set of operations in a hot strip rolling mill, and is a complex unit including many processes and control loops. Its modelling is a challenging task due to the variety of phenomena that occur within the mill, and variable transport delays. Model validation is also challenging due to a scarcity of measurements. On the other hand, a dynamic model that adequately reflects the numerous interactions between the mill units can be very useful for tasks such as high performance control design or vibration analysis. In this study, a one-dimensional model has been developed and validated against real plant data. The end use of the model is intended to be looper control analysis, but the model is kept sufficiently general so that it can be used or easily extended for other applications.     

Use of ionic liquid based chitosan as sorbent for preconcentration of fluoroquinolones in milk,egg, fish,bovine, and chicken meat samples by solid phase extraction prior to HPLC determination

The possibility of using ionic liquid based chitosan sorbent for the separation and preconcentration of fluoroquinolone antibiotics (marbofloxacin, enoxacin, ofloxacin, ciprofloxacin, and enrofloxacin) has been studied. For this reason, different ionic liquids were prepared and coated on the chitosan sorbent. The conditions of the preconcentration of fluoroquinolones on a microcolumn have been optimized and the extraction efficiencies of the prepared sorbents have been compared. The compounds were eluted with 5 mL of 20% NH₃ (v/v, MeOH) solution and determined by HPLC with diode array and fluorescence detector. The limits of detection were found as 4.23 µ g L^?1 for marbofloxacin, and 1.09 µg L^?1 for enoxacin; 3.23 × 10^?3 µg L^?1 for ofloxacin; 8.39 × 10^?3 µg L^?1 for ciprofloxacin; and 19.50 × 10^?3 µg L^?1 for enrofloxacin. The developed method was applied for the analysis of fluoroquinolone in milk, egg, fish, bovine, and chicken samples and the recoveries were obtained in the range 70–100%.