Extraction and reliable determination of acrylamide from thermally processed foods using ionic liquid-based ultrasound-assisted selective microextraction combined with spectrophotometry

Acrylamide (AAm) is a carcinogenic chemical that can form in thermally processed foods by the Maillard reaction of glucose with asparagine. AAm can easily be formed especially in frequently consumed chips and cereal-based foods depending on processing conditions. Considering these properties of AAm, a new, simple and green method is proposed for the extraction of AAm from thermally processed food samples. In this study, an ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate, [Bmim][BF₄]) as extractant was used in the presence of a cationic phenazine group dye, 3,7-diamino-5-phenylphenazinium chloride (PSH⁺, phenosafranine) at pH 7.5 for the extraction of AAm as an ion-pair complex from selected samples. Under optimum conditions, the analytical features obtained for the proposed method were as follows; linear working range, the limits of detection (LOD, 3S_b/m) and quantification (LOQ, 10S_b/m), preconcentration factor, sensitivity enhancement factor, sample volume and recovery% were 2.2–350 µg kg^?1, 0.7 µg kg^?1, 2.3 µg kg^?1, 120, 95, 60 mL and 94.1–102.7%, respectively. The validity of the method was tested by analysis of two certified reference materials (CRMs) and intra-day and inter-day precision studies. Finally, the method was successfully applied to the determination of AAm levels in thermally processed foods using the standard addition method.     

An Inexpensive and Sensitive Method for Speciative Determination of Sn(IV), Sn(II), and Total Sn as Sn(IV) in Selected Beverages by Micellar Improved Spectrophotometry

Food Analytical Methods - In the present study, an inexpensive, selective, and micellar sensitive spectrophotometric method for Sn(IV) was developed at 537 nm. The method is based on the...     

Involvement of GPx-3 in the Reciprocal Control of Redox Metabolism in the Leukemic Niche

The bone marrow (BM) microenvironment plays a crucial role in the development and progression of leukemia (AML). Intracellular reactive oxygen species (ROS) are involved in the regulation of the biology of leukemia-initiating cells, where the antioxidant enzyme GPx-3 could be involved as a determinant of cellular self-renewal. Little is known however about the role of the microenvironment in the control of the oxidative metabolism of AML cells. In the present study, a coculture model of BM mesenchymal stromal cells (MSCs) and AML cells (KG1a cell-line and primary BM blasts) was used to explore this metabolic pathway. MSC-contact, rather than culture with MSC-conditioned medium, decreases ROS levels and inhibits the Nrf-2 pathway through overexpression of GPx3 in AML cells. The decrease of ROS levels also inactivates p38MAPK and reduces the proliferation of AML cells. Conversely, contact with AML cells modifies MSCs in that they display an increased oxidative stress and Nrf-2 activation, together with a concomitant lowered expression of GPx-3. Altogether, these experiments suggest that a reciprocal control of oxidative metabolism is initiated by direct cell–cell contact between MSCs and AML cells. GPx-3 expression appears to play a crucial role in this cross-talk and could be involved in the regulation of leukemogenesis.     

Microprocessor-controlled mixing system for rebreathing equilibration

A simple, economic, and accurate microprocessor system for the determination of mixed venous PCO2 has been described. Through the automatic gas mixing system, it is possible to facilitate the use of the rebreathing equilibration technique for the purpose of cardiac output calculations. It was also possible to flush the rebreathing bag within a brief time, providing the investigator with an automatic three-way valve driven by a solenoid.     

Rarefied gas dynamics aspects of pharmaceutical freeze-drying

Freeze-drying is a low-pressure, low-temperature condensation pumping process widely used in manufacture of bio/pharmaceutical products. Because of the need to avoid the aggressive evaporation drying, typical operating pressures in freeze-drying are below 100 Pa. Understanding relevant rarefied flow physics can help improve freeze-drying systems and processes. The paper presents various rarefied gas dynamics aspects of freeze-drying including thermal creep and conduction, pressure and concentration-gradient driven flows and sonic expansion flows with icing. In particular, flow through the duct where the Knudsen number is small enough is modeled using conventional CFD techniques. The effect of the hardware on flow in the duct is discussed in detail. Furthermore, flow and icing in the freeze-drying condenser is modeled using the direct simulation Monte Carlo (DSMC) technique. The effect of duct length on the uniformity of mass flux and ice accretion rates are discussed. It is found that by increasing the duct length, there is a trade-off between increased residual pressure and improved uniformity. The simulations show that by augmenting the DSMC method with conventional CFD technique in appropriate regimes, the gas dynamics in the entire freeze-dryer system can be modeled numerically for given sublimation rate and geometry.     

Search for ionisation density effects in the radiation absorption stage in LiF:Mg,Ti

Optical absorption (OA) dose-response of LiF:Mg,Ti (TLD-100) is studied as a function of electron energy (ionisation density) and irradiation dose. Contrary to the situation in thermoluminescence dose-response where the supralinearity is strongly energy-dependent, no dependence of the OA dose filling constants on energy is observed. This result is interpreted as indicating a lack of competitive process in the radiation absorption stage. The lack of an energy dependence of the dose filling constant also suggests that the charge carrier migration distances are sufficiently large to smear out the differences in the non-uniform distribution of ionisation events created by the impinging gamma/electron radiation of various energies.     

Political orientation and modern versus aversive racism: Tests of Dovidio and Gaertner's (1998) integrated model.

According to J. F. Dovidio and S. L. Gaertner's (1998) integrated model of racism, politically liberal European Americans tend to express racism differently than conservative European Americans, with liberals demonstrating aversive racism and conservatives, symbolic or modern racism. In support of the model, in Experiment 1 liberals showed bias in favor of a twice-prosecuted African American relative to a European American in their judgment of double jeopardy, whereas conservatives did the reverse. Experiment 2 replicated these effects while eliminating a confound in the design of Experiment 1. Experiment 3 found evidence for the intrapsychic conflict hypothesized to underlie aversive racism. Specifically, only liberals displayed greater physiological arousal to the touch of an African American versus a European American experimenter. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dynamic analysis of removal and selective oxidation of H2S to elemental sulfur over Cu-V and Cu-V-Mo mixed oxides in a fixed bed reactor

Selective oxidation of H₂S to elemental sulfur was studied using the Cu-V and Cu-V-Mo mixed oxide catalysts with different O₂/H₂S ratios between 0 and 3. High activities and high sulfur selectivities reaching 0.98 were obtained with the Cu-V catalyst. The Cu-V-Mo mixed oxide catalyst showed higher activity with a somewhat less selectivity. The Cu-V catalyst, which was originally in the form of α-Cu₂V₂O₇, was converted to Cu₃VS₄, CuS and VO_x during the initial stages of reaction. Oxidized form of the catalyst resulted in the formation of mostly SO₂. Partially reduced catalyst containing V⁺² and V⁺⁴ was highly selective for the production of elemental sulfur, which was produced by a series of redox reactions involving lattice oxygen.