Modifying Mesoporous SBA-15 by a Microencapsulation Method in the Matrix of Sodium Alginate

The present work represents hydrogel as a composite based on sodium alginate and mesoporous SBA-15. The hydrogel was obtained by modifying mesoporous SBA-15 by a microencapsulation method of the SBA-15 in the sodium alginate matrix. The solution of CaCl2 provided a gelation complex of sodium alginate/SBA-15 in a rigid gel-like structure. The sodium alginate/SBA-15 hydrogels beads of about 3 mm diameter were prepared. Composite material was characterized by using powder X- ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis. This composite material may have potential application in removal of metal ions – pollutants from aqueous solutions.XVI International Conference on Fundamental and Applied Aspects of Physical Chemistry : Proceedings, Vol. 2, September 26-30, Belgrad

Seasonal Variations of the Activity of Antioxidant Defense Enzymes in the Red Mullet (Mullus barbatus l.) from the Adriatic Sea

This study investigated seasonal variations of antioxidant defense enzyme activities: total, manganese, copper zinc containing superoxide dismutase (Tot SOD, Mn SOD, CuZn SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR) and biotransformation phase II enzyme glutathione-S-transferase (GST) activity in the liver and white muscle of red mullet (Mullus barbatus). The investigations were performed in winter and spring at two localities: Near Bar (NB) and Estuary of the River Bojana (EB) in the Southern Adriatic Sea. At both sites, Mn SOD, GSH-Px, GR and GST activities decreased in the liver in spring. In the white muscle, activities of Mn SOD, GSH-Px, GR and GST in NB decreased in spring. GR decreased in spring in EB, while CAT activity was higher in spring at both sites. The results of Principal Component Analysis (PCA) based on correlations indicated a clear separation of various sampling periods for both investigated tissues and a marked difference between two seasons. Our study is the first report on antioxidant defense enzyme activities in the red mullet in the Southern Adriatic Sea. It indicates that seasonal variations of antioxidant defense enzyme activities should be used in further biomonitoring studies in fish species

Different Anesthesia in Rat Induces Distinct Inter-Structure Brain Dynamic Detected By Higuchi Fractal Dimension

The complexity, entropy and other non-linear measures of the electroencephalogram ( EEG), such as Higuchi fractal dimension (FD), have been recently proposed as the measures of anesthesia depth and sedation. We hypothesized that during unconciousness in rats induced by the general anesthetics with opposite mechanism of action, behaviorally and poligraphically controlled as appropriately achieved stable anesthesia, we can detect distinct inter-structure brain dynamic using mean FDs. We used the surrogate data test for nonlinearity in order to establish the existence of nonlinear dynamics, and to justify the use of FD as a nonlinear measure in the time series analysis. The surrogate data of predefined probability distribution and autocorrelation properties have been generated using the algorithm of statically transformed autoregressive process (STAP). FD then is applied to quantify EEG signal complexity at the cortical, hippocampal and pontine level during stable general anesthesia (ketamine/xylazine or nembutal anesthesia). Our study showed for the first time that global neuronal inhibition caused by different mechanisms of anesthetic action induced distinct brain inter- structure complexity gradient in Sprague Dawley rats. EEG signal complexities were higher at cortical and hippocampal level in ketamine/ xylazine vs. nembutal anesthesia, with the dominance of hippocampal complexity. In nembutal anesthesia the complexity dominance moved to pontine level, and ponto- hippocampocortical decreasing complexity gradient was established. This study has proved the Higuchi fractal dimension as a valuable tool for measuring the anesthesia induced inter- structure EEG complexity.Serbian Ministry of Science and Technological Development [173022]; NIH [AG16303

Different Anesthesia in Rat Induces Distinct Inter-Structure Brain Dynamic Detected By Higuchi Fractal Dimension

The complexity, entropy and other non-linear measures of the electroencephalogram ( EEG), such as Higuchi fractal dimension (FD), have been recently proposed as the measures of anesthesia depth and sedation. We hypothesized that during unconciousness in rats induced by the general anesthetics with opposite mechanism of action, behaviorally and poligraphically controlled as appropriately achieved stable anesthesia, we can detect distinct inter-structure brain dynamic using mean FDs. We used the surrogate data test for nonlinearity in order to establish the existence of nonlinear dynamics, and to justify the use of FD as a nonlinear measure in the time series analysis. The surrogate data of predefined probability distribution and autocorrelation properties have been generated using the algorithm of statically transformed autoregressive process (STAP). FD then is applied to quantify EEG signal complexity at the cortical, hippocampal and pontine level during stable general anesthesia (ketamine/xylazine or nembutal anesthesia). Our study showed for the first time that global neuronal inhibition caused by different mechanisms of anesthetic action induced distinct brain inter- structure complexity gradient in Sprague Dawley rats. EEG signal complexities were higher at cortical and hippocampal level in ketamine/ xylazine vs. nembutal anesthesia, with the dominance of hippocampal complexity. In nembutal anesthesia the complexity dominance moved to pontine level, and ponto- hippocampocortical decreasing complexity gradient was established. This study has proved the Higuchi fractal dimension as a valuable tool for measuring the anesthesia induced inter- structure EEG complexity.Serbian Ministry of Science and Technological Development [173022]; NIH [AG16303

Independent complexity patterns in single neuron activity induced by static magnetic field

We applied a combination of fractal analysis and Independent Component Analysis (ICA) method to detect the sources of fractal complexity in snail Br neuron activity induced by static magnetic field of 2.7 mT. The fractal complexity of Br neuron activity was analyzed before (Control), during (MF), and after (AMF) exposure to the static magnetic field in six experimental animals. We estimated the fractal dimension (FD) of electrophysiological signals using Higuchi's algorithm, and empirical FD distributions. By using the Principal Component Analysis (PCA) and FastICA algorithm we determined the number of components, and defined the statistically independent components (ICs) in the fractal complexity of signal waveforms. We have isolated two independent components of the empirical FD distributions for each of three groups of data by using FastICA algorithm. ICs represent the sources of fractal waveforms complexity of Br neuron activity in particular experimental conditions. Our main results have shown that there could be two opposite intrinsic mechanisms in single snail Br neuron response to static magnetic field stimulation. We named identified ICs that correspond to those mechanisms - the component of plasticity and the component of elasticity. We have shown that combination of fractal analysis with ICA method could be very useful for the decomposition and identification of the sources of fractal complexity of bursting neuronal activity waveforms. (C) 2011 Elsevier Ireland Ltd. All rights reserved.Ministry of Education and Science, Republic of Serbia [OI 173027, OI 173022

Sinteza i karakterizacija nanokompozita Ag/PS

Ispitivan je uticaj površinski modifikovanih nanočestica srebra (Ag) na optičke i termičke osobine matrice polistirena (PS). Obojeni transparentni nanokompozitni filmovi, dobijeni direktnim mešanjem nanočestica Ag i komercijalnog PS, okarakterisani su UV-Vis i IR spektroskopijom. Termičke osobine nanokompozitnih filmova su ispitivane metodama termogravimetrijske analize (TGA) i diferencijalne skanirajuće kalorimetrije (DSC). Termička stabilnost polimerne matrice, u azotu i na vazduhu, raste sa povećanjem sadržaja nanočestica srebra. Temperatura staklastog prelaza PS opada u prisustvu nanočestica Ag u odnosu na čist polimer

Surrogate data modeling the relationship between high frequency amplitudes and Higuchi fractal dimension of EEG signals in anesthetized rats

We used spectral analysis and Higuchi fractal dimension (FD) to correlate the EEG spectral characteristics of the sensorimotor cortex, hippocampus, and pons with their corresponding EEG signal complexities in anesthetized rats. We have explored the quantitative relationship between the mean FDs and EEG wide range high frequency (8-50 Hz) activity during ketamine/xylazine versus nembutal anesthesia at surgical plane. Using FD we detected distinct inter-structure complexity pattern and uncovered for the first time that the polygraphically and behaviorally defined anesthetized state at surgical plane as equal during experiment in two anesthetic regimens, is not the same with respect to the degree of neuronal activity (degree of generalized neuronal inhibition achieved) at different brain levels. Using the correlation of certain brain structure EEG spectral characteristics with their corresponding FDs, and the surrogate data modeling, we determined what particular frequency band contributes to EEG complexities in ketamine/xylazine versus nembutal anesthesia. In this study we have shown that the quantitative relationship between higher frequency EEG amplitude and EEG complexity is the best-modeled by surrogate data as a 3rd order polynomial. On the base of our EEG amplitude/EEG complexity relationship model, and the evidenced spectral differences in ketamine versus nembutal anesthesia we have proved that higher amplitudes of sigma, beta, and gamma frequency in ketamine anesthesia yields to higher FDs. (C) 2011 Elsevier Ltd. All rights reserved.Serbian Ministry of Education and Science [OI 173022]; NIH [AG16303

Cortico-pontine theta carrier frequency phase shift across sleep/wake states following monoaminergic lesion in rat

This study was aimed to explore the sleep/wake states related cortico-pontine theta carrier frequency phase shift following a systemically induced chemical axotomy of the monoaminergic afferents within a brain of the freely moving rats. Our experiments were performed in 14 adult, male Sprague Dawley rats, chronically implanted for sleep recording. We recorded sleep during baseline condition, following sham injection (saline i.p. 1 ml/kg), and every week for 5 weeks following injection of the systemic neurotoxins (DSP-4 or PCA; 1 ml/kg, i.p.) for chemical axotomy of the locus coeruleus (LC) and dorsal raphe (DR) axon terminals. After sleep/wake states identification, FFT analysis was performed on 5 s epochs. Theta carrier frequency phase shift (Delta Phi) was calculated for each epoch by averaging theta Fourier component phase shifts, and the Delta Phi values were plotted for each rat in control condition and 28 days following the monoaminergic lesions, as a time for permanently established DR or LC chemical axotomy. Calculated group averages have shown that Delta Phi increased between pons and cortex significantly in all sleep/wake states (Wake, NREM and REM) following the monoaminergic lesions, with respect to controls. Monoaminergic lesions established the pontine leading role in the brain theta oscillations during all sleep/wake states.Serbian Ministry of Education and Science [OI173022]; NIH [AG016303]

Surrogate data modeling the relationship between high frequency amplitudes and Higuchi fractal dimension of EEG signals in anesthetized rats

We used spectral analysis and Higuchi fractal dimension (FD) to correlate the EEG spectral characteristics of the sensorimotor cortex, hippocampus, and pons with their corresponding EEG signal complexities in anesthetized rats. We have explored the quantitative relationship between the mean FDs and EEG wide range high frequency (8-50 Hz) activity during ketamine/xylazine versus nembutal anesthesia at surgical plane. Using FD we detected distinct inter-structure complexity pattern and uncovered for the first time that the polygraphically and behaviorally defined anesthetized state at surgical plane as equal during experiment in two anesthetic regimens, is not the same with respect to the degree of neuronal activity (degree of generalized neuronal inhibition achieved) at different brain levels. Using the correlation of certain brain structure EEG spectral characteristics with their corresponding FDs, and the surrogate data modeling, we determined what particular frequency band contributes to EEG complexities in ketamine/xylazine versus nembutal anesthesia. In this study we have shown that the quantitative relationship between higher frequency EEG amplitude and EEG complexity is the best-modeled by surrogate data as a 3rd order polynomial. On the base of our EEG amplitude/EEG complexity relationship model, and the evidenced spectral differences in ketamine versus nembutal anesthesia we have proved that higher amplitudes of sigma, beta, and gamma frequency in ketamine anesthesia yields to higher FDs. (C) 2011 Elsevier Ltd. All rights reserved.Serbian Ministry of Education and Science [OI 173022]; NIH [AG16303

Cortico-pontine theta carrier frequency phase shift across sleep/wake states following monoaminergic lesion in rat

This study was aimed to explore the sleep/wake states related cortico-pontine theta carrier frequency phase shift following a systemically induced chemical axotomy of the monoaminergic afferents within a brain of the freely moving rats. Our experiments were performed in 14 adult, male Sprague Dawley rats, chronically implanted for sleep recording. We recorded sleep during baseline condition, following sham injection (saline i.p. 1 ml/kg), and every week for 5 weeks following injection of the systemic neurotoxins (DSP-4 or PCA; 1 ml/kg, i.p.) for chemical axotomy of the locus coeruleus (LC) and dorsal raphe (DR) axon terminals. After sleep/wake states identification, FFT analysis was performed on 5 s epochs. Theta carrier frequency phase shift (Delta Phi) was calculated for each epoch by averaging theta Fourier component phase shifts, and the Delta Phi values were plotted for each rat in control condition and 28 days following the monoaminergic lesions, as a time for permanently established DR or LC chemical axotomy. Calculated group averages have shown that Delta Phi increased between pons and cortex significantly in all sleep/wake states (Wake, NREM and REM) following the monoaminergic lesions, with respect to controls. Monoaminergic lesions established the pontine leading role in the brain theta oscillations during all sleep/wake states.Serbian Ministry of Education and Science [OI173022]; NIH [AG016303]