Analysis of phenothiazines in human body fluids using disk solid-phase extraction and liquid chromatography

Seven phenothiazine derivatives, perazine, perphenazine, prochlorperazine, propericiazine, thioproperazine, trifluoperazine, and flupentixol, have been found to be extractable from human plasma and urine samples using disk solid-phase extraction (SPE) with an Empore C18 cartridge. Human plasma and urine (1 mL each) containing the 7 phenothiazine derivatives were mixed with 2 mL of 0.1M NaOH and 7 mL distilled water and then poured into the disk SPE cartridges. The drugs were eluted with 1 mL chloroform- acetonitrile (8 + 2) and determined by liquid chromatography with ammonium formate/formic acid-acetonitrile gradient elution. The detection was performed by ultraviolet absorption at 250 nm. The separation of the 7 phenothiazine derivatives from each other and from impurities was generally satisfactory using a SymmetryShield RP8 column (150 x 2.1 mm id, 3.5 microm particle size). The recoveries of the 7 phenothiazine derivatives spiked into plasma and urine samples were 64.0-89.9% and 65.1-92.1%, respectively. Regression equations for the 7 phenothiazine derivatives showed excellent linearity, with detection limits of 0.021-0.30 microg/mL for plasma and 0.017-0.30 microg/mL for urine. The within-day and day-to-day coefficients of variation for both samples were commonly below 9.0 and 14.9%, respectively.     

Cholesteric induction power of β-galactose derivatives

Galactose derivatives were explored as chiral dopants, effective for inducing chiral nematic liquid crystal (LC) phases. Galactose bearing O-isopropylidene substituents at the C3 and C4 and butoxybiphenyl substituents at the C2 and C6 positions exhibits a high helical twisting power (HTP) value of ?74.4 μm^?1. Such a high HTP value for the galactose derivative is attributed to (1) linkage of the C3 and C4 carbons with the O-isopropylidene substituent, which places the C2 and C6 substitutes in a skew arrangement at a large angle and (2) enhancement of the affinity with the host nematic LCs by incorporating aromatic substituents at the C2 and C6 positions that are similar to those in the host.     

Determination of long-lived radionuclides in radioactive wastes from the IEA-R1 nuclear research reactor

Ion-exchange resins and activated charcoal beds are employed for purification of the cooling water that is pumped through the core of pool type nuclear research reactors. Once expended, these media are replaced and become radioactive wastes that contain low concentrations of long-lived fission and activation products, uranium isotopes and transuranium elements. Determination of the radioactive inventory is of paramount importance in the management of such radioactive wastes, which, besides high-energy photon emitters that can be identified and quantified directly by gamma-ray spectrometry, also contain pure alpha, pure beta and low-energy photon emitters whose quantitative determination require radiochemical separation. These later are collectively known as difficult to measure (DTM) radionuclides. A characterization program embracing the DTM radionuclides is currently in progress for spent ion-exchange resins and activated charcoal beds that were definitively withdrawn from the water cleanup system of the IEA-R1 nuclear research reactor. Radiochemical methods used in the characterization program include separations with specific anionic resins, chromatographic extractions and co-precipitation, which enabled the measurement of the activity concentrations of ⁹⁰Sr, ²³⁴U, ²³⁵U, ²³⁸U, ²³⁸Pu, ^239+240Pu, ²⁴¹Pu, ²⁴¹Am and ²⁴⁴Cm. An enhanced retention of uranium and transuranium elements was observed in the activated charcoal compared to the ion-exchange resins as a result of the tendency of actinides to undergo hydrolysis in aqueous solutions.     

Impact of operational changes on the scaling factors of radioactive wastes from the IEA-R1 research reactor

Nowadays, the scaling factor methodology is widely used in order to estimate the activity concentration of difficult to measure nuclides in low- and intermediate-level waste from nuclear reactors. However, very few experimental studies evaluate how operational changes in the reactors affect scaling factors. The present work examines the impact of operational changes on the scaling factors that were determined for spent ion-exchange resins and spent activated charcoal permanently withdrawn as radioactive wastes from the water cleanup system of the IEA-R1 nuclear research reactor.     

Triangular arbitrage as an interaction among foreign exchange rates

We first show that there are in fact triangular arbitrage opportunities in the spot foreign exchange markets, analyzing the time dependence of the yen–dollar rate, the dollar–euro rate and the yen–euro rate. Next, we propose a model of foreign exchange rates with an interaction. The model includes effects of triangular arbitrage transactions as an interaction among three rates. The model explains the actual data of the multiple foreign exchange rates well.     

An X-ray diffraction study of anharmonic thermal vibrations in the ionic conductor,barium chloride fluoride (BaClF)

Integrated intensities of X-ray reflections from a barium chloride fluoride single crystal were measured at 24, 180, 289, 402, 467 and 610°C. The intensities were used for the determination of the anharmonic potential parameters up to the third order. Harmonic potential parameters for each ion were obtained from the temperature dependence of thermal parameters, and anharmonic potential parameters were determined by the least-squares procedures, utilizing the temperature factor formalism based on the cumulant expansion. As a result, it has been found that the Ba²⁺ and Cl^? ions show an anharmonicity, while no significant anharmonic effect was detected for the F^? ion. From the potential calculated around the Cl^? and F^? ions, it was found that both Cl^? and F^? ions diffuse more easily within the (001) plane than along the c axis.     

Turbulent heat transfer in a flat plate boundary layer disturbed by a cylinder

Augmentation of heat transfer from a flat plate using a turbulence promoter has been studied. A circular cylinder 8 mm in diameter was placed in the turbulent boundary layer detached from the flat plate. It was located parallel to the plate and perpendicular to the flow direction. Clearance, c, between the cylinder and the flat plate was varied in nine steps: c=0, 1, 2, 3, 4, 6, 11, 20 and 29.5 mm. Measurements were made of the local heat transfer coefficients, mean velocity profiles, turbulence intensity profiles, static pressure and skin friction. Experimental results showed that the heat transfer deterioration which occurs just downstream of the cylinder at c=0 mm can be removed by displacing the cylinder a small distance from the wall. The improvement in heat transfer is mainly due to the unsteadiness of the recirculating flow on the plate and the effect of intense turbulence arriving at the near wall region from the lower shear layer of the cylinder wake. Heat transfer augmentation is most effective when c=4 mm and becomes less effective when c is increased more than 6 mm. The enhancement disappears far downstream from the cylinder.     

Continuous relaxation for discrete DC programming

Discrete DC programming with convex extensible functions is studied. A natural approach for this problem is a continuous relaxation that extends the problem to a continuous domain and applies the algorithm in continuous DC programming. By employing a special form of continuous relaxation, which is named “lin-vex extension,” the produced optimal solution of the extended continuous relaxation coincides with the solution of the original discrete problem. The proposed method is demonstrated for the degree-concentrated spanning tree problem, the unfair flow problem, and the correlated knapsack problem.