Graphene-based humidity sensors: the origin of alternating resistance change.

The response of a graphene-based humidity sensor is considered as a function of film structures. Analysis of the resistance changes due to water molecule adsorption on the graphene or multi-layer graphene (MLG) surface is performed for films with different structures and resistivities from hundreds of ohms/sq to hundreds of kilo-ohms/sq. The results revealed possible increase, decrease and non-monotonous behavior of resistance with changes in film structure. Adsorption of water molecules at grain boundary defects is assumed to lead to an increase in film resistivity due to the donor property of water and the p-type conductivity of graphene. Another type of conductive center with a higher capture cross-section is realized in the case of water molecule adsorption at edge defects in MLG films (the formation of conductive chains with ionic conductivity). If these chains form a continuous network the film resistivity decreases. The result of the competition between the opposite effects of the conductivity compensation and formation of the water-based conductive chains depends on the film structure and determines the response of humidity sensors. Sensor sensitivity is found to increase when only one type of defect determines water adsorption (edge defects or grain boundary defects).

[Evaluation of blood hematological and biochemical parameters by bioimpedance spectroscopy].

The purpose of the study was to determine the capability of bioimpedance spectroscopy (BIS) to evaluate the hematological and biochemical parameters of blood. BIS readings were estimated on an ABC-01 Medass hardware-computer complex; blood hematological and biochemical parameters (n = 46) were determined on automated analyzers. The BIS readings were found to be closely correlated with packed cell volume and hemoglobin and red blood cell values, but weakly related to plasma biochemical parameters and white blood cell counts. BIS readings may be used to calculate red blood cell counts taken in units of measurement in hematological practice, by applying the multiple regression equations. Thus, the blood BIS technique may be employed to estimate basic hematological parameters (hemoglobin concentration, red blood cell counts, and packed cell volume).

Technology of Two-dimensional Bioimpedance Analysis of the Human Body Composition.

The BIA primary result sheets as a rule contain one-dimensional graphical scales with a selected area of normal values. In 1994, Piccoli et al. proposed BIVA, an alternative form of BIA data presentation, where two bioimpedance parameters are considered simultaneously as tolerance ellipses: resistance and reactance normalized to height. The purpose of this study is to develop an approach to data analysis in body composition bioimpedance research in two-dimensional representations. The data of 1.124.668 patients aged 5 to 85 years who underwent a bioimpedance study in Russian Health Centers from 2009 to 2015 were used. Statistical programming in the R Studio environment was carried out to estimate two-dimensional distribution densities of pairs of body composition parameters for each year of life. The non-Gaussian distribution is found in most parameters of bioimpedance analysis of body composition for most ages (Lilliefors test, p-value << 0.0001). The slices of the actual two-dimensional distribution pairs of body composition parameters had an irregular shape. The authors of the article propose using the actually observed distribution for populations where numerous bioimpedance studies have already been carried out. Such technology can be called two-dimensional bioimpedance analysis of human body composition (2DBIA). The 2DBIA approach is clearer for practitioners and their patients due to the use of body composition parameters in addition to electrical impedance parameters.

[A portable impedance meter for monitoring liquid compartments of human body under space flight conditions].

A portable two-frequency tetrapolar impedance meter was developed to study the state of liquid compartments of human body under zero-gravity conditions. The portable impedance meter makes it possible to monitor the hydration state of human body under conditions of long-term space flight on board international space station.

Effect of acute and chronic glucocorticoid treatments on epithelial cell proliferation in the esophagus and small intestine of rats.

Data about glucocorticoid influence on proliferation in the esophagus and small intestine are very contradictory and need to be reexamined. Moreover, only the effects of acute or short-term treatments with glucocorticoids have been demonstrated, whereas nothing is known about their effects under chronic exposure. This work was therefore carried out to examine proliferative activity in the esophagus and small intestine under conditions of acute and chronic glucocorticoid exposure. Rats were treated with either glucocorticoid triamcinolone acetonide or vehicle for 3, 33, or 63 days. Proliferation was assessed in the basal layer of esophageal epithelium and in the epithelium of jejunal crypts, using three criteria, as the number of mitotic, bromodeoxyuridine-labelled, and proliferating cell nuclear antigen-labelled cells. Treatment with glucocorticoid for 3 days led to a slight decrease in all parameters in the esophageal epithelium and had almost no effect on proliferation in the epithelium of jejunal crypts. Long-term treatment with glucocorticoid for either 33 or 63 days resulted in an increase in all parameters tested in both esophageal and jejunal crypt epithelia. Sixty-three-day treatment had a more prominent and significant (P < 0.05) effect. These results suggest that acute glucocorticoid treatment nonsignificantly reduces the number of cells in the cell cycle in the esophageal epithelium, whereas chronic treatment increases the number of proliferating cells in both esophageal and jejunal crypt epithelia.

Two month glucocorticoid treatment increases estradiol-induced stromal and myometrial cell proliferation in the uterus of ovariectomized rats.

The present work was undertaken to examine the effect of 2 month glucocorticoid treatment on estradiol-induced proliferation in the uterus. Ovariectomized rats were treated with long-acting triamcinolone acetonide or saline for 60 days followed by a single injection of estradiol dipropionate or vehicle. Proliferation in the uterus was estimated by the mitotic index, bromodeoxyuridine-labelling index and proliferating cells nuclear antigen-labelling index 24, 36 and 48 h after the injection of estradiol or vehicle. Two month glucocorticoid treatment resulted in an initial decrease in all the parameters for luminal and glandular epithelia followed by an increase to 48 h after estradiol injection, and in a large increase in all proliferative parameters for stromal and myometrial cells at all periods of observation, compared with control rats untreated with glucocorticoid. The 2 month glucocorticoid treatment protocol had no significant effect on the parameters without estradiol administration. Analysis of proliferation for myometrial cells was also performed after 1 month treatment with glucocorticoid followed by estradiol or saline. Results showed no significant influence of 1 month treatment with glucocorticoid on myometrial cells.

[Automated measurement of cardiac output during physical exercise using a rheographic method]. / Avtomatizirovannoe izmerenie serdechnogo vybrosa reograficheskim metodom prifizicheskikh nagruzkakh.

The authors propose the methods of measuring the hemodynamic indices on the basis of the impedance rheoplethysmography, electrocardiometer and programming microcalculator. The use of the disk electrodes instead of the circular electrodes makes it possible to take measurements during physical tests, e.g. veloergometric tests.

[Effect of hyperventilation on the cerebral blood flow and metabolism in patients with craniocerebral trauma]. / Tserebral'nyi krovotok i metabolizm vo vremia giperventiliatsii u bol'nykh s izolirovannoi cherepno-mozgovoi travmoi.

Cerebral blood flow and metabolism were studied in 44 patients with acute severe craniocerebral injuries (contusions of the brain and removal of intracranial hematomas) with consciousness depression (moderate coma), hospitalized in intensive neurological care wards. Oxygen supply to the brain was repeatedly evaluated (acid-base status of the jugular vein blood, oxygen arterio-venous difference, oxygen extraction coefficient), oxymetry of the brain was repeatedly carried out, and vital functions were monitored over the entire period of disease. Cerebral blood flow was monitored by rheoencephalography, which helped timely detect the changes in cerebral blood flow in patients with craniocerebral injuries during different ventilation protocols used in intensive care. All studies were carried out during three stages: 1) initial stage, when the patients were brought to intensive neurological care wards after surgical intervention, and during normoventilation (paCO2 36-40 mm Hg; 2) moderate hyperventilation (paCO2 35-26 mm Hg); and 3) pronounced hyperventilation (paCO2 25-20 mm Hg). Specific changes in the cerebral blood flow during the acute period of craniocerebral injury were detected during different ventilation regimens in 2 groups of patients: group 1 with lethal outcomes and group 2 with positive changes.

[Evaluation of aqueous compartments of the body by integral bioimpedance spectrometry in x-ray surgical interventions in children]. / Otsenka vod'nykh sektorov organizma metodom integral'noi bioimpedansnoi spektrometrii pri rentgenokhirurgicheskikh vmeshatel'stvakh u detei.

There were studied 14 children (mean age 5.71 +/- 0.60 years, body weight 18.95 +/- 3.50 kg, height 101.0 +/- 4.03 cm) with initially normal osmotic and volumic status. Plasma osmolarity, blood aldosterone level, aqueous compartments balance were (evaluated by segmented bioimpedance spectrometry), urine osmolarity and diuresis were investigated after bolus injection of x-ray contrast agent (RCA) urografin-60% (mean volume 2 ml/kg for 2-4 sec). A statistically significant gradual decrease in the total volume of water (TVW) in the organism was observed, with 8.53% deficiency of TVW by the second hour after RCA injection in comparison with the initial level. TVW deficiency developed as the result of diuresis which increased 7-fold in the presence of increased plasma osmolarity after injection of RCA bolus. Correction of the volume of circulating blood and plasma was carried out mainly at the expense of intracellular liquid, whose deficiency was actually 4.5 times higher than of extracellular liquid. Bioimpedance spectrometry indicated centralized redistribution of water in the organism, as TVW deficiency was mainly due to water in the limbs. The results indicate the need in infusion therapy after RCA injection in order to correct the resultant water deficit.

Two-month glucocorticoid treatment increases proliferation in the stomach and large intestine of rats.

BACKGROUND/AIMS: It has been shown that acute or short-term treatments with glucocorticoids lead to a marked decrease in proliferation in the stomach and large intestine. The effects of more prolonged glucocorticoid treatment on cell renewal in these organs are not known. The present work was therefore undertaken to examine the proliferative activity in the stomach and colon during 2 months of glucocorticoid treatment in comparison with shorter treatments. METHODS: Rats were treated with either the glucocorticoid triamcinolone acetonide or vehicle for 63, 33 or 3 days. Proliferation was assessed in the glandular epithelium of the fundal part of the stomach and in the epithelium of the colonic crypts using three criteria: the mitotic index; the bromodeoxyuridine labelling index, and the proliferating cell nuclear antigen-labelling index (percentage of mitotic or labelled cells). RESULTS: Treatment with glucocorticoid for 63 days resulted in a very significant increase in all proliferative parameters tested in the gastric mucosa and the colonic crypts. On the contrary, treatments with glucocorticoid for 3 or 33 days had a marked inhibitory influence on proliferation in these tissues. CONCLUSION: As opposed to treatments for 3 or 33 days, glucocorticoid treatment for 2 months leads to an increase in the number of cycling cells in the gastric and colonic mucosae.