Estimation of geomagnetic field disturbance using the wavelet transform

This paper discusses the main aspects of geomagnetic data processing using the wavelet transform. The wavelet transform is shown to be efficient for automatic extraction of unperturbed level of the horizontal component of the Earth’s magnetic field. As a result, it becomes possible to significantly reduce the errors arising during automatic calculations of the local geomagnetic activity index (local K-index) in comparison with adaptive smoothing (KAsm is Adaptative Smoothing method) recommended by INTERMAGNET. It has been found that prior to magnetic storms, we can observe a weak rise of geomagnetic activity in different frequency bands connected with the development of an approaching storm.     

Eu(III)-coupled luminescent multi-walled carbon nanotubes in surfactant solutions

A carbon nanotube/inorganic hybrid material has been fabricated by coupling Eu(III) complexes onto multi-walled carbon nanotubes (MWCNTs). Successful coupling has been verified by X-ray photoelectron spectroscopy (XPS) measurement where a clear signal from Eu3d has been identified. When sonicated in hexaethylene glycol monododecyl ether (C₁₂E₆) or sodium dodecyl sulfate (SDS) aqueous solutions, the MWCNTs with Eu-complex attached (denoted as Eu-MWCNTs hereafter) can be dispersed. UV–vis measurements on a dilute dispersion of Eu-MWCNTs in SDS aqueous solution reveal the characteristic absorption from Eu(III) complexes, which gives further proof of the successful coupling. The strong luminescent properties of Eu-MWCNTs allow them to be observed directly under a fluorescence microscope. Interestingly, it is found that Eu-MWCNTs can undergo continuous movements in C₁₂E₆ or SDS dilute solutions. When Eu-MWCNTs are incorporated into the lyotropic liquid crystal phase formed by C₁₂E₆ (above 40% by weight), however, movements have been hindered. Small angle X-ray scattering measurements showed that Eu-MWCNTs are ordered in the lyotropic liquid crystal. Fluorescence microscopy observations reveal that the luminescent properties of the Eu-MWCNTs have not been affected by the liquid crystalline surfactant matrix.     

Analyzing subtle features of natural time series by means of a wavelet-based approach

The present paper is devoted to the development of methods and approaches intended for the analysis of natural time series. Due to the strong variability, irregularity, and complex structure of the time series in question, the problem of automatic processing, i.e., in automatic mode, is rather complicated and merits further investigation in order to produce better solutions than those that presently exist. Relying on contemporary methods of signal processing, signal analysis, and recognition of complex data, we have suggested a new wavelet-based approach, which allows one to extract subtle structural features from a complex natural time series in an automatic mode. After that, it becomes possible to identify these features and analyze them in terms of a particular knowledge domain. Our methods and approaches have been successfully tested on the Earth??s magnetic field data obtained from the Paratunka observatory (Paratunka village, Kamchatka region, Far East of Russia).     

Thermodynamic Modeling of MgO-Al2O3-TiO2 System

This scientific paper gives consideration to the information on the structure of the triple component system,in particular MgO-Al2O3-TiO2 that serves as a basis...     

Holographic patterning of luminescent photopolymer nanocomposites

Volume phase gratings in the photopolymerisable composites, containing luminescent nanoparticles have been fabricated for the first time. Nanoparticles of LaPO₄, doped by Ce³⁺ and Tb³⁺ ions (the trade name is REN-X-green) with high luminescence quantum yield were used as a luminescent inorganic additive. The holographic gratings in such materials are formed as a result of the diffusion distribution of the nanoparticles during exposure of photopolymerisable composites to interference pattern. The influence of the pre-polymer formulation and the holographic patterning parameters on the grating formation is comprehensively investigated. The use of the optimised pre-polymer syrup containing two monomers with sufficiently different polymerisation rates allows fabrication of gratings with diffraction efficiency up to 80% at low optical losses (< 5%) (20 μm film thickness). To obtain maximum diffraction efficiency the intensity and the period of the interference pattern were optimised for each formulation. In addition maximum diffraction efficiency was achieved with the nanocomposites containing 30–32 wt.% of nanoparticles. On the other hand the highest possible modulation of the nanoparticles' concentration was obtained for the concentration of about 20 wt.%. In this case maximum ordering of the nanoparticles in the polymer matrix is achieved. The photoluminescence of the nanoparticles within the homogeneous polymer film and within the grating has been measured. The example application of the photopolymerisable composite containing luminescence inorganic nanoparticles in holographic security technology has been demonstrated.     

The expression of transforming growth factor beta in pregnant rat myometrium is hormone and stretch dependent

From a quiescent state in early pregnancy to a highly contractile state in labor, the myometrium displays tremendous growth and remodeling. We hypothesize that the transforming growth factor beta (TGFbeta) system is involved in the differentiation of pregnant myometrium throughout gestation and labor. Furthermore, we propose that during pregnancy the mechanical and hormonal stimuli play a role in regulating myometrial TGFbetas. The expression of TGFbeta1-3 mRNAs and proteins was examined by real-time PCR, Western immunoblot, and localized with immunohistochemistry in the rat uterus throughout pregnancy and labor. Tgfbeta1-3 genes were expressed differentially in pregnant myometrium. Tgfbeta2 gene was not affected by pregnancy, whereas the Tgfbeta1 gene showed a threefold increase during the second half of gestation. In contrast, we observed a dramatic bimodal change in Tgfbeta3 gene expression throughout pregnancy. Tgfbeta3 mRNA levels first transiently increased at mid-gestation (11-fold on day 14) and later at term (45-fold at labor, day 23). Protein expression levels paralleled the changes in mRNA. Treatment of pregnant rats with the progesterone (P4) receptor antagonist RU486 induced premature labor on day 19 and increased Tgfbeta3 mRNA, whereas artificial maintenance of elevated P4 levels at late gestation (days 20-23) caused a significant decrease in the expression of Tgfbeta3 gene. In addition, Tgfbeta3 was up-regulated specifically in the gravid horn of unilaterally pregnant rats subjected to a passive biological stretch imposed by the growing fetuses, but not in the empty horn. Collectively, these data indicate that the TGFbeta family contributes in the regulation of myometrial activation at term integrating mechanical and endocrine signals for successful labor contraction.     

Study of the formation processes of gold droplet arrays on Si substrates by high temperature anneals

In this study, the peculiarities of the transformations of gold films deposited on the Si wafer surfaces as a result of high temperature anneals are investigated experimentally depending on the conditions of wafer surface preparation and the annealing regimes. The morphology and the distribution functions of the crystallites of gold films as well as the gold droplets formed as a result of anneals are studied as functions of annealing temperature, type of annealing (rapid thermal or rapid furnace annealing), and the state of the surface of Si wafers. The results obtained can be used for the controlled preparation of the arrays of catalytic gold droplets for subsequent growth of Si wire-like crystals.     

Protective Effect of Water-Soluble C60 Fullerene Nanoparticles on the Ischemia-Reperfusion Injury of the Muscle Soleus in Rats

The biomechanical parameters of muscle soleus contraction in rats and their blood biochemical indicators after the intramuscular administration of water-soluble C₆₀ fullerene at doses of 0.5, 1, and 2 mg/kg 1 h before the onset of muscle ischemia were investigated. In particular, changes in the contraction force of the ischemic muscle soleus, the integrated power of the muscle, the time to achieve the maximum force response, the dynamics of fatigue processes, and the parameters of the transition from dentate to smooth tetanus, levels of creatinine, creatine kinase, lactate and lactate dehydrogenase, and parameters of prooxidant–antioxidant balance (thiobarbituric acid reactive substances, hydrogen peroxide, and reduced glutathione and catalase) were analyzed. The positive therapeutic changes in the studied biomechanical and biochemical markers were revealed, which indicate the possibility of using water-soluble C₆₀ fullerenes as effective prophylactic nanoagents to reduce the severity of pathological conditions of the muscular system caused by ischemic damage to skeletal muscles.