scholarly journals Absorption X-ray in quartz crystal with temperature gradient

2009 ◽  
Vol 65 (a1) ◽  
pp. s199-s200
Author(s):  
Vahan R. Kocharyan
2014 ◽  
Vol 70 (a1) ◽  
pp. C1137-C1137
Author(s):  
Vahan Kocharyan ◽  
Sargis Khlopuzyan ◽  
Poghos Grigoryan ◽  
Edik Baghdasaryan ◽  
Ruben Amiraghyan

The research of the focusing and defocusing of the diffracted X-rays with different wave fronts in crystals under the influences of the temperature gradient and the ultrasonic vibrations is given in the works [1,2]. This work is dedicated experimentally investigation of Laue diffraction of the hard X-rays in quartz single crystals under the influence of the temperature gradient. It is shown that the reflected beams under the influence of the temperature gradient are focused. When the vector of the temperature gradient is anti parallel to the diffraction vector, in accordance to the increasing value of the temperature gradient the focus point continuously approaches the crystal. When the vector of the temperature gradient is parallel to the diffraction vector, in accordance with the increasing value of the temperature gradient the focus point continuously distances itself from the crystal, and at a certain value of the temperature gradient it becomes a plane wave. Parallel to the further increasing of the temperature gradient we see an imaginary focus, which continuously approaches the entry surface of the crystal. It is shown that by using a thicker single crystal it is possible to focus and pump a larger angular and spectral width of X-rays in the direction of diffraction.


Author(s):  
A R Mkrtchyan ◽  
A P Potylitsyn ◽  
A V Vukolov ◽  
A I Novokshonov ◽  
A S Gogolev ◽  
...  

Author(s):  
A. R. Mkrtchyan ◽  
A. P. Potylitsyn ◽  
A. V. Vukolov ◽  
A. I. Novokshonov ◽  
A. S. Gogolev ◽  
...  

2011 ◽  
Vol 286 (41) ◽  
pp. 35699-35707 ◽  
Author(s):  
Attila Iliás ◽  
Károly Liliom ◽  
Brigitte Greiderer-Kleinlercher ◽  
Stephan Reitinger ◽  
Günter Lepperdinger

Hyaluronan (HA), a polymeric glycosaminoglycan ubiquitously present in higher animals, is hydrolyzed by hyaluronidases (HAases). Here, we used bee HAase as a model enzyme to study the HA-HAase interaction. Located in close proximity to the active center, a bulky surface loop, which appears to obstruct one end of the substrate binding groove, was found to be functionally involved in HA turnover. To better understand kinetic changes in substrate interaction, binding of high molecular weight HA to catalytically inactive HAase was monitored by means of quartz crystal microbalance technology. Replacement of the delimiting loop by a tetrapeptide interconnection increased the affinity for HA up to 100-fold, with a KD below 1 nm being the highest affinity among HA-binding proteins surveyed so far. The experimental data of HA-HAase interaction were further validated showing best fit to the theoretically proposed sequential two-site model. Besides the one, which had been shown previously in course of x-ray structure determination, a previously unrecognized binding site works in conjunction with an unbinding loop that facilitates liberation of hydrolyzed HA.


2021 ◽  
Vol 28 (3) ◽  
Author(s):  
Daisuke Ishikawa ◽  
Alfred Q. R. Baron

The detailed fabrication and performance of the temperature-gradient analyzers that were simulated by Ishikawa & Baron [(2010). J. Synchrotron Rad. 17, 12–24] are described and extended to include both quadratic and 2D gradients. The application of a temperature gradient compensates for geometric contributions to the energy resolution while allowing collection of a large solid angle, ∼50 mrad × 50 mrad, of scattered radiation. In particular, when operating relatively close to backscattering, π/2 − θB = 1.58 mrad, the application of a gradient of 1.32 K per 80 mm improves the measured total resolution from 60 to 25 meV at the full width at half-maximum, while when operating further from backscattering, π/2 − θB = 6.56 mrad, improvement from 330 to 32 meV is observed using a combination of a gradient of 6.2 K per 80 mm and dispersion compensation with a position-sensitive detector. In both cases, the operating energy was 15.8 keV and the incident bandwidth was 22 meV. Notably, the use of a temperature gradient allows a relatively large clearance at the sample, permitting installation of more complicated sample environments.


2011 ◽  
Vol 38 (8) ◽  
pp. 0815001
Author(s):  
刘利锋 Liu Lifeng ◽  
肖沙里 Xiao Shali ◽  
毋玉芬 Wu Yufen ◽  
钱家渝 Qian Jiayu ◽  
施军 Shi Jun ◽  
...  
Keyword(s):  

2019 ◽  
Vol 13 (9) ◽  
pp. 2345-2359 ◽  
Author(s):  
Pascal Hagenmuller ◽  
Frederic Flin ◽  
Marie Dumont ◽  
François Tuzet ◽  
Isabel Peinke ◽  
...  

Abstract. The deposition of light-absorbing particles (LAPs) such as mineral dust and black carbon on snow is responsible for a highly effective climate forcing, through darkening of the snow surface and associated feedbacks. The interplay between post-depositional snow transformation (metamorphism) and the dynamics of LAPs in snow remains largely unknown. We obtained time series of X-ray tomography images of dust-contaminated samples undergoing dry snow metamorphism at around −2 ∘C. They provide the first observational evidence that temperature gradient metamorphism induces dust particle motion in snow, while no movement is observed under isothermal conditions. Under temperature gradient metamorphism, dust particles can enter the ice matrix due to sublimation–condensation processes and spread down mainly by falling into the pore space. Overall, such motions might reduce the radiative impact of dust in snow, in particular in arctic regions where temperature gradient metamorphism prevails.


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