460,891 research outputs found
Characteristic of Individual Indicators of Endogenous Intoxication in the Experimental Asthma Dynamics and Their Correction by Thiotriasolin
The aim of this work was to find out the specifics of changes in endogenous intoxication, middle mass molecules (MMM) and erythrocyte intoxication index (EII) in the blood of animals for experimental asthma in different periods of its development and to correct them by thiotriazolin.Material and methods. Researches were carried out on 72 Guinea-pigs (males), which were divided into 6 groups for 12 animals in each of them. The last sixth group included animals that were treated by thiotriazolin. The drug thiotriazolin rate of 100 mg / kg intramuscularly since 23rd day of the experiment for 10 days was administered in the animals of sixth group. Experimental model of bronchial asthma was restored on Guinea-pigs by the V.I. Babych method (1979). In all groups of animals there were determined the middle mass molecules concentration in blood in the wave of 254 nm by I.A.Volchehorskiy, D.A.Dyatlova, E.I. Lvovska and others methods and EII by V.K. Kazymyrko V.I. Maltsev methods. Numerical results were adapted with static method using Student\u27s criteria.Results of the research. The highest level of endogenous intoxication in the blood was in the fifth group of Guinea pigs with asthma (33rd day), indicating the direct dependence of the antigenic effect on their severity. Using of the thiotriazolin within 10 days (from 23rd to 33rd day) caused the decrease of the MMM254 concentration and EII in serum compared with a group of Guinea pigs, that were not entered the medicine. It approved its treating effect.Conclusions. So, the research of middle mass molecules and erythrocyte intoxication index indicators in different periods of experimental asthma showed their gradual increase in serum of Guinea pigs with the greatest severity in 33rd day of the experiment. It might indicate the development of endogenous intoxication animals. But the using of thiotriazolin caused the decreasing of these indicators. That gives a reason to state its positive effect on some markers of endogenous intoxication and feasibility of further researches
Bound states of charges on top of graphene in magnetic field
We show theoretically that in the external magnetic field like charges on top
of graphene monolayer may be mutually attracted to form macro-molecules. For
this to happen graphene needs to be in Quantum Hall plateau state with local
chemical potential being between the Landau levels. Graphene electron(s) gets
localized in the middle between charges and provides overscreening of Coulomb
repulsion between the charges. The size of the resulting macro-molecules is of
the order of the magnetic length ( nm for magnetic field 10 T). The
possible stable macro-molecules that unit charges can form on graphene in
magnetic field are classified. The binding survives significant temperatures,
exceeding mobility barriers for many ionically bond impurities. The influence
of possible lattice-scale effects of valley-mixing are discussed.
Tuning the doping of graphene or the magnetic field, the binding of
impurities can be turned on and off and the macro-molecule size may be tuned.
This opens the perspective to nanoscopic manipulation of ions on graphene by
using magnetic field and gating.Comment: 9 pages, revised text, added refs, added a chapter on Valley-mixin
EPR Study of Spin Labeled Brush Polymers in Organic Solvents
Spin-labeled polylactide brush polymers were synthesized via ring-opening metathesis polymerization (ROMP), and nitroxide radicals were incorporated at three different locations of brush polymers: the end and the middle of the backbone, and the end of the side chains (periphery). Electron paramagnetic resonance (EPR) was used to quantitatively probe the macromolecular structure of brush polymers in dilute solutions. The peripheral spin-labels showed significantly higher mobility than the backbone labels, and in dimethylsulfoxide (DMSO), the backbone end labels were shown to be more mobile than the middle labels. Reduction of the nitroxide labels by a polymeric reductant revealed location-dependent reactivity of the nitroxide labels: peripheral nitroxides were much more reactive than the backbone nitroxides. In contrast, almost no difference was observed when a small molecule reductant was used. These results reveal that the dense side chains of brush polymers significantly reduce the interaction of the backbone region with external macromolecules, but allow free diffusion of small molecules
NMR measurements on intercalated 3R-TaS2.Ix (I=NH3 and N2H4)
Proton nuclear magnetic resonance was used to probe the environment of the intercalant molecule in low dimensional (aeolotropic) solids 3RI-TaS2(NH3)2/3 and 3RII-TaS2(N2H4)4/3, and, specifically to look for phase transitions associated with changes in superlattice geometry. The proton resonance frequency for the intercalated molecules in the temperature interval 200 to 300K indicates that there are different magnetic environments in three temperature domains. (i) There is only one resonance field for molecules in isotropic magnetic environments. (ii) The high- and low-temperature domains (I and III) have molecules in only two different environments, whereas in the middle temperature domain (II) there are at least four different magnetic environments. (iii) The different magnetic environments measured by the ratio of anisotropic to isotropic resonance absorption intensity (rai) indicate that the ratios rai are constants of the sample in domains I and II. (iv) At low temperatures (domain III), rai depends on magnetic field polarisation effects and the temperature treatment of the sample. The authors conclude that the different magnetic environments observed for ammonia and hydrazine appear to be determined by the host, octahedrally coordinate TaS2
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A Simple Graphene NH₃ Gas Sensor via Laser Direct Writing.
Ammonia gas sensors are very essential in many industries and everyday life. However, their complicated fabrication process, severe environmental fabrication requirements and desorption of residual ammonia molecules result in high cost and hinder their market acceptance. Here, laser direct writing is used to fabricate three parallel porous 3D graphene lines on a polyimide (PI) tape to simply construct an ammonia gas sensor. The middle one works as an ammonia sensing element and the other two on both sides work as heaters to improve the desorption performance of the sensing element to ammonia gas molecules. The graphene lines were characterized by scanning electron microscopy and Raman spectroscopy. The response and recovery time of the sensor without heating are 214 s and 222 s with a sensitivity of 0.087% ppm-1 for sensing 75 ppm ammonia gas, respectively. The experimental results prove that under the optimized heating temperature of about 70 °C the heaters successfully help implement complete desorption of residual NH₃ showing a good sensitivity and cyclic stability
Dynamic hydration valve controlled ion permeability and stability of NaK channel
The K^+^, Na^+^, Ca^2+^ channels are essential to neural signalling, but our current knowledge at atomic level is mainly limited to that of K^+^ channels. Unlike a K^+^ channel having four equivalent K^+^-binding sites in its selectivity filter, a NaK channel conducting both Na^+^ and K^+^ ions has a vestibule in the middle part of its selectivity filter, in which ions can diffuse but not bind specifically. However, how the NaK channel conducts ions remains elusive. Here we find four water grottos connecting with the vestibule of the NaK selectivity filter. Molecular dynamics and free energy calculations show that water molecules moving in the vestibule-grotto complex hydrate and stabilize ions in the filter and serve as a valve in conveying ions through the vestibule for controllable ion permeating. During ion conducting, the water molecules are confined within the valve to guarantee structure stability. The efficient exquisite hydration valve should exist and play similar roles in the large family of cyclic nucleotide-gated channels which have similar selectivity filter sequences. The exquisite hydration valve mechanism may shed new light on the importance of water in neural signalling
Cytoplasmic DNA in the unfertilized sea urchin egg: Physical properties of circular mitochondrial DNA and the occurrence of catenated forms
The mitochondrial DNA in the unfertilized egg of the sea urchin Lytechinus pictus is present in an amount approximately seven times that of the haploid nuclear DNA.(1) The mitochondrial DNA has a higher buoyant density than the nuclear DNA and consists of circular duplex molecules of a uniform size of about 5µ. The circular DNA has been recovered(1) in both the intact (closed) and nicked (open) states characteristic of the circular duplex viral DNA's(2) and the mitochondrial DNA's from birds and mammals.(3, 4
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