Noise Estimation in Electroencephalogram Signal by Using Volterra Series Coefficients

The Volterra model is widely used for nonlinearity identification in practical applications. In this paper, we employed Volterra model to find the nonlinearity relation between electroencephalogram (EEG) signal and the noise that is a novel approach to estimate noise in EEG signal. We show that by employing this method. We can considerably improve the signal to noise ratio by the ratio of at least 1.54. An important issue in implementing Volterra model is its computation complexity, especially when the degree of nonlinearity is increased. Hence, in many applications it is urgent to reduce the complexity of computation. In this paper, we use the property of EEG signal and propose a new and good approximation of delayed input signal to its adjacent samples in order to reduce the computation of finding Volterra series coefficients. The computation complexity is reduced by the ratio of at least 1/3 when the filter memory is 3.

Immunomodulatory Properties of Taranjebin (Camel’s Thorn) Manna and Its Isolated Carbohydrate Macromolecules

Taranjebin manna is a substance produced by Poophilus nebulosus Leth. (Aphrophoridae) larva that feed from host plant Alhagi maurorum (Leguminosae). In Persian ethnomedicine, it is used as an antipyretic, antiviral, antimicrobial, demulcent, and adaptogen. But it is contraindicated in acute fever and some infections. This controversy might be due to its immunomodulatory properties. This study evaluated immunomodulatory properties of Taranjebin and its macromolecules. Taranjebin solution was prepared as described in traditional literature. After dialysis and precipitation, the macromolecules were isolated on DEAE Sephadex A-25. The cytotoxic/proliferative properties of Taranjebin and its isolated macromolecules on human Jurkat E6.1 cells were investigated (15.62-1000 μg/mL) using WST-1 reagent. Three of 4 isolated acidic polysaccharides inhibited the proliferation of Jurkat cells in a dose-dependent manner at concentrations higher than 31.25 μg/mL (IC50 range of 44.81-147.97 μg/mL). The crude aqueous Taranjebin solution had proliferative effects. These results indicate the immunomodulatory properties of Taranjebin.

Immunomodulatory properties of Trehala manna decoction and its isolated carbohydrate macromolecules

ETHNOPHARMACOLOGICAL RELEVANCE

Trehala manna (Shekar tighal) is a cocoon-shaped manna produced by larval activity of Curculionidae family on some Echinops species. In Persian traditional medicine, it is used not only for the treatment of fever and constipation but also for sore throat, influenza and some other viral and bacterial infections which seems to be related to its boosting effects on immune system. The aim of this study was to evaluate immunomodulatory properties of Trehala manna and its isolated polysaccharides.

MATERIALS AND METHODS

Several carbohydrate macromolecules were isolated from Trehala manna decoction using solvent-solvent extraction, ion exchange and size-exclusion chromatography. The macromolecules were characterized by gas chromatography-mass spectrometry and spectrophotometric methods. The immunomodulatory effects of Trehala manna decoction and its isolated polysaccharides were evaluated on Jurkat cells at different concentrations using WST-1 reagent.

RESULTS

Seven water-soluble polysaccharides were isolated with the structures of rhamnogalacturonan, glucogalacturonan, manno-arabinogalacturonan or homogalacturonan and the molecular weights (MW) of ≤1.67-667 ≤ kDa. Large polysaccharides with MW ≥667 kDa and pectin inhibited the proliferation of Jurkat cells in a dose-dependent manner with the IC50 range of 98.06-429.53 µg/mL. The IC50 for low MW polysaccharides (around 1 kDa) did not show considerable cytotoxicity (IC50>1000 µg/mL), in contrast, they exhibited a dose-dependent enhancement of cell proliferation at concentration range of 15.62-62.50 μg/mL.

CONCLUSION

Trehala aqueous decoction and its isolated polysaccharides showed some immunomodulatory effects on Jurkat cell line in a dose-dependent manner and the molecular weight of these polysaccharides also revealed a great impact on their cytotoxic/proliferative properties.

A New Adaptive Diffusive Function for Magnetic Resonance Imaging Denoising Based on Pixel Similarity

Although there are many methods for image denoising, but partial differential equation (PDE) based denoising attracted much attention in the field of medical image processing such as magnetic resonance imaging (MRI). The main advantage of PDE-based denoising approach is laid in its ability to smooth image in a nonlinear way, which effectively removes the noise, as well as preserving edge through anisotropic diffusion controlled by the diffusive function. This function was first introduced by Perona and Malik (P-M) in their model. They proposed two functions that are most frequently used in PDE-based methods. Since these functions consider only the gradient information of a diffused pixel, they cannot remove noise in noisy images with low signal-to-noise (SNR). In this paper we propose a modified diffusive function with fractional power that is based on pixel similarity to improve P-M model for low SNR. We also will show that our proposed function will stabilize the P-M method. As experimental results show, our proposed function that is modified version of P-M function effectively improves the SNR and preserves edges more than P-M functions in low SNR.

Analysis of ammonia separation from purge gases in microporous hollow fiber membrane contactors

In this study, a mathematical model was developed to analyze the separation of ammonia from the purge gas of ammonia plants using microporous hollow fiber membrane contactors. A numerical procedure was proposed to solve the simultaneous linear and non linear partial differential equations in the liquid, membrane and gas phases for non-wetted or partially wetted conditions. An equation of state was applied in the model instead of Henry's law because of high solubility of ammonia in water. The experimental data of CO₂-water system in the literature was used to validate the model due to the lack of data for ammonia-water system. The model showed that the membrane contactor can separate ammonia very effectively and with recoveries higher than 99%. SEM images demonstrated that ammonia caused some micro-cracks on the surfaces of polypropylene fibers, which could be an indication of partial wetting of membrane in long term applications. However, the model results revealed that the membrane wetting did not have significant effect on the absorption of ammonia because of very high solubility of ammonia in water. It was also found that the effect of gas velocity on the absorption flux was much more than the effect of liquid velocity.