[Dynamics of the profile of biochemical markers of arterial hypertension in the elderly patients under exposure to a physical load]. / Dinamika profilia biokhimicheskikh markerov arterial'noi gipertenzii u pozhilykh patsientov pri vozdeistvii fizicheskoi nagruzki.

BACKGROUND: The elderly age is an independent, non-modifiable risk factor for the development of cardiovascular diseases, including arterial hypertension (AH). One of the causes attributable to the increase in the number of cardiovascular diseases (including hypertension) is a decrease in the level of the motor activity in humans under the modern living conditions. In connection with this, the modern society is actively looking for various means that could contribute to the prolongation of active human longevity. The regular physical activity can and should be the most important among such means. AIM: The objective of the present work was to study the biochemical markers of arterial hypertension in the elderly patients and the influence of physical activity on their dynamics. MATERIAL AND METHODS: The study involved the elderly patients including 148 ones at the age from 60 to 74 years who underwent examination and/or treatment for stage I-II arterial hypertension (AH I-II) based at the medical facilities of the city of Stavropol. 30.4% of these patients were men and 69.6% women. All of them were asked to take the drugs needed to treat hypertension during a period of 12 months. The patients were divided into two groups. The first group (the main group) consisted of 72 patients (48.6%) who receivedregular sessions of medical physical training, in addition to conventional drug therapy. The patients who received only medication were referred to the second group comprised of 76 subjects (51.4%). RESULTS: The results of the study give evidence that the combination of the physical exercises with standard drug therapy in the elderly and senile patients presenting with AH I-II promotes considerable improvement in the overall health status of the treated patients including red blood indices (p<0.05). The more pronounced influence of the treatment on the biochemical indices of endothelial dysfunction (the homocysteine level) and lipid metabolism (total cholesterol) was documented in the group of the patients who practiced exercise therapy (p<0,05) than in those comprising the group of comparison treated in the absence of exercise therapy (p=0). The greatest effect was observed after 6 months from the beginning of the exercise therapy. CONCLUSIONS: The investigation into the biological markers of arterial hypertension in the elderly patients with this pathological condition has demonstrated that the regularly practiced moderate physical exercises (exercitation, walking) leads to a significant decrease of the homocysteine level as well as the normalization of lipid metabolism and indices of the red blood.

Er-doped light emitting slot waveguides monolithically integrated in a silicon photonic chip.

An integrated erbium-based light emitting diode has been realized in a waveguide configuration allowing 1.54 µm light signal routing in silicon photonic circuits. This injection device is based on an asymmetric horizontal slot waveguide where the active slot material is Er(3+) in SiO2 or Er(3+) in Si-rich oxide. The active horizontal slot waveguide allows optical confinement, guiding and lateral extraction of the light for on-chip distribution. Light is then coupled through a taper section to a passive Si waveguide terminated by a grating which extracts (or inserts) the light signal for measuring purposes. We measured an optical power density in the range of tens of µW/cm(2) which follows a super-linear dependence on injected current density. When the device is biased at high current density, upon a voltage pulse (pump signal), free-carrier and space charge absorption losses become large, attenuating a probe signal by more than 60 dB/cm and thus behaving conceptually as an electro-optical modulator. The integrated device reported here is the first example, still to be optimized, of a fundamental block to realize an integrated silicon photonic circuit with monolithic integration of the light emitter.

Electrical pump & probe and injected carrier losses quantification in Er doped Si slot waveguides.

Electrically driven Er(3+) doped Si slot waveguides emitting at 1530 nm are demonstrated. Two different Er(3+) doped active layers were fabricated in the slot region: a pure SiO(2) and a Si-rich oxide. Pulsed polarization driving of the waveguides was used to characterize the time response of the electroluminescence (EL) and of the signal probe transmission in 1 mm long waveguides. Injected carrier absorption losses modulate the EL signal and, since the carrier lifetime is much smaller than that of Er(3+) ions, a sharp EL peak was observed when the polarization was switched off. A time-resolved electrical pump & probe measurement in combination with lock-in amplifier techniques allowed to quantify the injected carrier absorption losses. We found an extinction ratio of 6 dB, passive propagation losses of about 4 dB/mm, and a spectral bandwidth > 25 nm at an effective d.c. power consumption of 120 µW. All these performances suggest the usage of these devices as electro-optical modulators.

Erbium emission in MOS light emitting devices: from energy transfer to direct impact excitation.

The electroluminescence (EL) at 1.54 µm of metal­oxide­semiconductor (MOS) devices withEr3C ions embedded in the silicon-rich silicon oxide (SRSO) layer has been investigated under different polarization conditions and compared with that of erbium doped SiO2 layers. EL time-resolved measurements allowed us to distinguish between two different excitation mechanisms responsible for the Er3C emission under an alternate pulsed voltage signal (APV). Energy transfer from silicon nanoclusters (Si-ncs) to Er3C is clearly observed at low-field APV excitation. We demonstrate that sequential electron and hole injection at the edges of the pulses creates excited states in Si-ncs which upon recombination transfer their energy to Er3C ions. On the contrary, direct impact excitation of Er3C by hot injected carriers starts at the Fowler­Nordheim injection threshold (above 5 MV cm(-1)) and dominates for high-field APV excitation.

Dielectric study of the antiplasticization of trehalose by glycerol.

Recent measurements have suggested that the antiplasticizing effect of glycerol on trehalose can significantly increase the preservation times of proteins stored in this type of preservative formulation. In order to better understand the physical origin of this phenomenon, we examine the nature of antiplasticization in trehalose-glycerol mixtures by dielectric spectroscopy. These measurements cover a broad frequency range between 40 Hz to 18 GHz (covering the secondary relaxation range of the fragile glass-former trehalose and the primary relaxation range of the strong glass-former glycerol) and a temperature (T) range bracketing room temperature (220 K to 350 K). The Havriliak-Negami function precisely fits our relaxation data and allows us to determine the temperature and composition dependence of the relaxation time tau describing a relative fast dielectric relaxation process appropriate to the characterization of antiplasticization. We observe that increasing the glycerol concentration at fixed T increases tau (i.e., the extent of antiplasticization) until a temperature dependent critical "plasticization concentration" xwp is reached. At a fixed concentration, we find a temperature at which antiplasticization first occurs upon cooling and we designate this as the "antiplasticization temperature," Tant. The ratio of the tau values for the mixture and pure trehalose is found to provide a useful measure of the extent of antiplasticization, and we explore other potential measures of antiplasticization relating to the dielectric strength.