The basic possibility of creation of high speed cryogenic monodisperse targets is shown. According to calculations at input of thin liquid cryogenic jets with a velocity of bigger 100 m/s in vacuum ...the jets don't manage to freeze at distance to 1 mm and can be broken into monodisperse drops. Drops due to evaporation are cooled and become granules. High speed cryogenic monodisperse targets have the following advantages: direct input in vacuum (there is no need for a chamber of a triple point chamber and sluices), it is possible to use the equipment of a cluster target, it is possible to receive targets with a diameter of D < 20 μk from various cryogenic liquids (H2, D2, N2, Ar,...) with dispersion less than 1%, the high velocity of monodisperse granules(> 100m/s), exact synchronization of the target hitting moment in a beam with the moment of sensors turning on.
The technique of the automated precision parameters diagnostics of the compelled capillary disintegration of liquid jet is developed for the solution of heat-physical problems of receiving the stable ...monodisperse drop streams. The analysis of the images received from two digital cameras, located at the angle ninety degrees to each other is the basic of this procedure. One of cameras fixes the image of a drop flow in plane X, another - in plane Y. The minimum time of storing images is ∼0.1 microsecond. By means of specially developed software in the "on line" mode it is possible to process images and to determine the following parameters: jets speed, drops speed, jets length, jets diameter and drops diameter. Testing on objects with the known geometrical sizes confirmed working capacity and efficiency of the technique and the software. The relative error of parameters determination does not exceed 0.5% for jets with length of several millimeters. The developed technique and the software allow to increase the accuracy and reliability of parameters determination of compelled capillary disintegration of liquid jets and drop streams and expand possibilities of parameters control of setups for receiving monodisperse streams.
The purpose of the present work is to numerically calculate cooling of thin deuterium jets to create units for receiving high-speed cryogenic monodisperse targets. The model of cryogenic jet outflow ...into the low pressure area has been created. Using PHOENICS software the temperature change of the surface and the interior of a jet over time for various external parameters has been investigated by the numerical method. The dependences of temperature changes of liquid deuterium jets have been obtained along the jet surface and along the radius depending on the jet diameter, velocity, initial jet temperature and pressure in the working chamber of units for receiving cryogenic monodisperse targets. The principal possibility of creating high-speed cryogenic monodisperse targets is shown. According to the calculations, at injection of thin liquid Deuterium jets with a speed of up to 100 ms‒1 into the working chamber with low pressure, the jets do not have time to freeze at a distance of up to 1 mm. The results of numerical calculations can be used to develop units for receiving high-speed cryogenic mono-disperse targets.
The purpose of work is development of the model and carrying out numerical calculations of cooling of thin jets from hydrogen and deuterium as applicable to installations for receiving cryogenic ...monodisperse targets. For this purpose the model of the expiration of a cryogenic jet to the low pressure area is created, the change of surface temperature and an internal jet part at different external parameters with respect to time is investigated through numerical solutions in PHOENICS software. Dependences of temperature change of liquid jets from hydrogen and deuterium along jet surface and on radius depending on jet diameter, speed, initial jet temperature and pressure in the working chamber of installations for receiving cryogenic monodisperse targets are carried out. The basic possibility of creation of high-speed cryogenic monodisperse targets is shown. According to calculations, at input of thin liquid jets of hydrogen or deuterium with a speed up to 100 m/s in the working chamber with low pressure, jets at distance up to 1 mm do not manage to freeze and can be broken into monodisperse drops. Drops are cooled and become granules due to evaporation. The developed model, the program for determination of parameters of steady monodisperse disintegration of liquid cryogenic jets and results of numerical calculations can be used during creation of installations for receiving high-speed cryogenic monodisperse targets.
The most generally useful methods for cleaning and processing of surfaces are the sand-jets and shot blasting jets. Installations of this kind are used for cleaning of corrosion surfaces, the ...oil-dirt deposits, paint coatings. However the use of these installations follows to high investment and operational expenditure, larger risk of operators disease, the negative affect for a environment. These problems can be solved with the use of new cleaning method through application of mono-disperse (identical by the size and the form) ice granules of 300 - 1000 microns, accelerated by air stream in the nozzle device to the speed of 10 - 100 m/s. In view of the extreme complexity of the receiving such particles by means of cooling and the subsequent freezing of water drops are necessary additional experimental researches. For study of thermal processes of receiving mono-disperse ice granules the experimental installation was created and experiments on deactivation and cleaning of surfaces with pollution of various types are made. Experiments showed that by means of a stream of the accelerated ice granules it is rather successfully possible to delete oil-dirt deposits, outdated paint coats and rust. Besides, efficient deactivation of radioactive surfaces is possible. The coefficient deactivation of γ activity is highest.
The development of accelerating and laser technologies has made the production of high-energy radiation beams possible. The beam interaction with cryogenic monodisperse targets can help in studying ...the extreme states of matter; creating compact electron, proton, and heavy ion accelerators; making isotopes and developing new methods in nuclear medicine; and creating new sources of radiation for micro- and nanoelectronics. The results presented in this paper are obtained by studying the problems of the monodisperse target production of cryogenic liquids (hydrogenium, nitrogen, etc.) and metals and their use in the applied tasks set for accelerating equipment.
We report development of generators for periodic, satellite-free fluxes of monodisperse drops with diameters down to 10 microm from cryogenic liquids such as H2, N2, Ar, and Xe (and, as a reference ...fluid, water). While the break up of water jets can be described well by Rayleigh's linear theory, we find jet regimes for H2 and N2 which reveal deviations from this behavior. Thus, Rayleigh's theory is inappropriate for thin jets that exchange energy and/or mass with the surrounding medium. Moreover, at high evaporation rates, the axial symmetry of the dynamics is lost. When the drops pass into vacuum, frozen pellets form due to surface evaporation. The narrow width of the pellet flux paves the way towards various industrial and scientific applications.
The translocation of the small GTP-binding protein Rho from the cytosolic to membrane-bound form is an early step in many cellular signal-transduction events, but little is known regarding the ...mechanism of Rho association with the plasma membrane. We have used membranes from human erythrocytes to uncover a novel class of integral membrane components involved in the Rho-membrane association. Membranes of human erythrocytes contain several proteins of the Ras superfamily. Using specific antibodies and C3 exoenzyme of Clostridium botulinum we have identified one of them as RhoA. This protein was detected in both cytosol and membrane fractions of hypotonically lysed erythrocytes. We found that cytosolic Rho bound specifically to the cytoplasmic surface of the erythrocyte membrane and that the translocation of Rho to the membrane was absolutely dependent on the prior incubation of the cytosol with guanosine 5'--gamma-thio-triphosphate (1-50 microM) at low Mg2+ concentration. Rho binding sites could not be extracted from the membrane using conditions that extracted all other peripheral proteins and were unaffected by heat treatment and protease digestion. Rho binding was saturable, with a Kd in the range 1-5.0 nM, and the number of binding sites was estimated to be approx. (1-2) x 10(3) sites per cell. This is the first report of Rho binding to integral membrane components. The identity of these components may reveal novel aspects of the mechanism by which Rho exerts its multiple biochemical effects.
Erythroid dematin is a major component of red blood cell junctional complexes that link the spectrin–actin cytoskeleton to the overlying plasma membrane. Transcripts of dematin are widely distributed ...including human brain, heart, lung, skeletal muscle, and kidney. In vitro, dematin binds and bundles actin filaments in a phosphorylation‐dependent manner. The primary structure of dematin consists of a C‐terminal domain homologous to the ‘headpiece’ domain of villin, an actin‐binding protein of the brush border cytoskeleton. Except filamentous actin, no other binding partners of dematin have been identified. To investigate the physiological function of dematin, we employed the yeast two‐hybrid assay to identify dematin‐interacting proteins in the adult human brain. Here, we show that dematin interacts with the guanine nucleotide exchange factor Ras‐GRF2 by yeast two‐hybrid assay, and this interaction is further confirmed by blot overlay, surface plasmon resonance, co‐transfection, and co‐immunoprecipitation assays. Human Ras‐GRF2 is expressed in a variety of tissues and, similar to other guanine nucleotide exchange factors (GEFs), displays anchorage independent growth in soft agar. Co‐transfection and immunoblotting experiments revealed that dematin blocks transcriptional activation of Jun by Ras‐GRF2 and activates ERK1 via a Ras‐GRF2 independent pathway. Because much of the present evidence has centered on the identification of the Rho family of GTPases as key regulators of the actin cytoskeleton, the direct association between dematin and Ras‐GRF2 may provide an alternate mechanism for regulating the activation of Rac and Ras GTPases via the actin cytoskeleton.
We report development of generators for periodic, satellite-free fluxes of mono-disperse drops with diameters down to 10 mikrometers from cryogenic liquids like H_2, N_2, Ar and Xe (and, as reference ...fluid, water). While the breakup of water jets can well be described by Rayleigh's linear theory, we find jet regimes for H_2 and N_2 which reveal deviations from this behavior. Thus, Rayleigh's theory is inappropriate for thin jets that exchange energy and/or mass with the surrounding medium. Moreover, at high evaporation rates, axial symmetry of the dynamics is lost. When the drops pass into vacuum, frozen pellets form due to surface evaporation. The narrow width of the pellet flux paves the way towards various industrial and scientific applications.
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