Evaluation of a model system for the selective study of the lipid peroxidation process

The effect of molecular environment on the peroxidation of linoleic acid (LA), a polyunsaturated fatty acid (PUFA), initiated by ferrous ions was investigated in acidic and neutral pH conditions. Mixed nonionic surfactants TWEEN®‐20/LA micelles were established as a model system to obtain a surfactant‐in‐lipid aqueous system at high acidity level. The peroxidation of LA was induced by ferrous ions and the kinetics of the produced conjugated dienes was followed by UV measurements and the ferric thiocynate method. Ferrous ions were oxidized only by the preformed LA hydroperoxides, which under established conditions produced lipid alkoxyl and peroxyl radicals as the sole initiators of propagation. The results revealed the LA peroxidation process remained mainly unaffected within the 2.5<pH<5.5 range, while highly pH sensitive around pH 7. The propagation process prevailed at optimal concentrations of 500 µM of LA and 280 µM TWEEN®‐20, and at the ferrous ion concentration up to 75 µM, irrespective of the buffer used. Practical applications: A simple model system in water, suitable for the selective study of the lipid peroxidation propagation phase induced by ferrous ion is presented here. Fatty acids serve as model compounds susceptible to processes associated with oxidative radical initiated‐modifications of lipids. The obtained results contribute to a better understanding of the oxidative behavior of lipids, particularly those soluble in nonionic surfactant micelles in acidic medium. The oxidative stability of the PUFA in model systems containing TWEEN®‐20 and ferrous ion at low pH could be predicted and controlled by measuring the lipid hydroperoxide formation. The experimental conditions presented may also provide a suitable system for the study of the termination phase of lipid peroxidation.     

Electromagnetic wave absorption by an organic resin solution based on ferrite particles with a spinel crystal structure

We have investigated an organic resin solution designed for EM wave absorption based on a magnetic filler, composed of phases within the Mn_0.66Zn_0.27Fe_2.07O₄ system, embedded in an absorber composite with concentration ratios of 50:50, 75:25 and 90:10 by weight. The formation of the manganese zinc ferrite particles, as the principal magnetic phases, was achieved via the conventional ceramic method. The electromagnetic parameters of the composites were measured with a vector network analyser at 100 MHz to 10 GHz. The subject of the paper was a study of the electromagnetic absorber properties and the rheological properties of the resin composite based on ferrite particles with respect to using the materials in architectural coatings.     

Antitumor Mechanisms of Amino Acid Hydroxyurea Derivatives in the Metastatic Colon Cancer Model

The paper presents a detailed study of the biological effects of two amino acid hydroxyurea derivatives that showed selective antiproliferative effects in vitro on the growth of human tumor cell line SW620. Tested compounds induced cell cycle perturbations and apoptosis. Proteins were identified by proteomics analyses using two-dimensional gel electrophoresis coupled to mass spectrometry, which provided a complete insight into the most probable mechanism of action on the protein level. Molecular targets for tested compounds were analyzed by cheminformatics tools. Zinc-dependent histone deacetylases were identified as potential targets responsible for the observed antiproliferative effect.     

Activity of antioxidants in solution and in irradiated heterogeneous system

The efficiency of some common antioxidants, α-tocopherol, butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), was studied relative to β-carotene in a homogeneous solution and in a model system of an irradiated solid food. Relative reactivities in homogeneous solution covered a range of three orders of magnitude, α-tocopherol being the best and BHT the poorest antioxidant of the three. In irradiated systems consisting of oleic acid coated on a solid support (egg white), the range of reactivities was much narrower within one order of magnitude. In solution, there was a parallelism of the relative reactivities with oxidizing alkoxyl radicals derived from oleic acid hydroperoxides andtert-butyl hydroperoxide. On the solid support the relative reactivities of α-tocopherol and BHA with oleic acid radiation-induced oxidizing radicals were reversed, BHA appearing the best. Efficient antioxidants do not retain their great antioxidant activity in comparison with the moderate ones on transition from a homogeneous solution to a heterogeneous system. Relative efficiencies of antioxidants do not critically depend on the nature of oxidizing radicals in heterogeneous media.     

Iron and manganese bacteria in Ranney wells

From an examination of water samples and of relevant plates (glass and metal ones) in the water of Ranney wells, iron and manganese bacteria have been studied.     

Gel Strength and Sensory Attributes of Fig (Ficus carica) Jams and Preserves as Influenced by Ripeness

ABSTRACT: In this article, gel strength and sensory attributes of jams and preserves made from figs at different stages of ripeness were investigated. Special emphasis was put on investigating the relationship of these attributes and pectin composition during ripening. Jams were produced with the addition of sugars and commercial pectin. In the production of preserves, no additional sugars or commercial pectin were used. Basic physicochemical properties (total solids, sugars, pH, total acidity) of figs were determined at all stages of ripeness. Total solids, sugars, and pH value increased in figs during ripening. To better understand the role of fig pectin in gel formation, the amount of 3 pectin fractions, soluble in water (PFW), soluble in oxalate (PFO), and soluble in alkali (PFA), as well as their gel-forming abilities were determined. The most abundant pectin fraction in figs was found to be PFO. Its amount was not influenced by the stage of ripeness. The amount of PFW and PFA decreased with increased ripeness of the fruit. Strength of gels formed with PFW and PFA isolated at different stages of ripeness followed the same trend. Gels made with PFO were remarkably softer in comparison with other gels. While strength of jams was not influenced by the ripeness of fig fruits, the strength of preserves decreased with increased ripeness of the fruit. The stage of ripeness did not have a significant influence on sensory attributes of jams or preserves. However, the type of product had a significant influence on taste, firmness, and color. Jams scored higher than preserves when these 3 attributes were evaluated.     

Effect of sequence selection on MAI suppression in limited spreading CDMA systems

Increasingly, spread spectrum systems are being proposed which support a range of data rates and traffic types in a band limited environment. One way to achieve a range of data rates with fixed bandwidth is to allow the use of different processing gains. If the range of data rates supported is large, the lower bound on the processing gain can become quite small. Receivers based on LMMSE algorithms offer high efficiency for CDMA systems through interference suppression, however at small processing gains, the sequence set correlation properties prove to be a significant limitation on the system efficiency. This paper provides examples of sets of short length spreading sequences which have good auto-correlation (AC) and cross-correlation (CC) properties which are essential to allow relatively high system efficiency. A CDMA system using an LMMSE receiver is examined with selected short length sets to demonstrate the application of the sequences. The sets proposed are compared to system performance when using well known sequence families. This revised version was published online in July 2006 with corrections to the Cover Date.     

The missing component in rail charging modeling—access charges principle selection

The motive of this research is the fact that until now no universal model of access charges (AC) has been defined. In the process of modeling, the AC principle is one of the key elements for defining the AC. In this paper, a model for the AC principle selection based on the analytic network process (ANP) approach is proposed. The developed model presents the objectives of the identified stakeholders through the established criteria from three different perspectives: the government influence, railway market environment, and efficiency of network use. Based on the results of a research, network structure of the ANP method can successfully resolve the dependence and conflicts among evaluation criteria for the AC principle selection. The proposed ANP‐based model can become a tool for evaluation and ranking of the AC principle as shown in the case study of the Serbian Railways. This paper is based on real data.     

The Code Design of the Space-time Trellis Codes with Dynamic Transmit Power Allocation

Space-time trellis codes (STTCs) have been shown to efficiently use transmit diversity to improve the error performance. In existing space-time trellis codes, the transmit power is equally distributed across all transmit antennas. However, this power allocation strategy is not optimum regarding the error performance. In this paper, we propose a design of space-time trellis codes with dynamic transmit power allocation (STTCs/DTPA), when partial channel state information (CSI) is available at the transmitter side. It is demonstrated that this new scheme can achieve a full diversity order and have much better error performance than the standard STTCs scheme, the existing STTCs/DTPA, and some other closed-loop transmit diversity schemes with partial CSI.