Semi-automated protein crystal mounting device for the sulfur single-wavelength anomalous diffraction method

Use of longer-wavelength X-rays has advantages for the detection of small anomalous signals from light atoms, such as sulfur, in protein molecules. However, the accuracy of the measured diffraction data decreases at longer wavelengths because of the greater X-ray absorption. The capillary-top mounting method (formerly the loopless mounting method) makes it possible to eliminate frozen solution around the protein crystal and reduces systematic errors in the evaluation of small anomalous differences. However, use of this method requires custom-made tools and a large amount of skill. Here, the development of a device that can freeze the protein crystal semi-automatically using the capillary-top mounting method is described. This device can pick up the protein crystal from the crystallization drop using a micro-manipulator, and further procedures, such as withdrawal of the solution around the crystal by suction and subsequent flash freezing of the protein crystal, are carried out automatically. This device makes it easy for structural biologists to use the capillary-top mounting method for sulfur single-wavelength anomalous diffraction phasing using longer-wavelength X-rays.

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X-Ray absorption edge elemental imaging of B. thuringienis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100153038 ◽

1989 ◽

Vol 47 ◽

pp. 212-213

Author(s):

R. L. Stears

Keyword(s):

Absorption Edge ◽

Elemental Distribution ◽

X Rays ◽

Differential Absorption ◽

Synchrotron Source ◽

High Brightness ◽

X Ray ◽

Elemental Imaging ◽

Cellular Integrity ◽

X Ray Absorption

Because of the nature of the bacterial endospore, little work has been done on analyzing their elemental distribution and composition in the intact, living, hydrated state. The majority of the qualitative analysis entailed intensive disruption and processing of the endospores, which effects their cellular integrity and composition.Absorption edge imaging permits elemental analysis of hydrated, unstained specimens at high resolution. By taking advantage of differential absorption of x-ray photons in regions of varying elemental composition, and using a high brightness, tuneable synchrotron source to obtain monochromatic x-rays, contact x-ray micrographs can be made of unfixed, intact endospores that reveal sites of elemental localization. This study presents new data demonstrating the application of x-ray absorption edge imaging to produce elemental information about nitrogen (N) and calcium (Ca) localization using Bacillus thuringiensis as the test specimen.

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Al-driven peculiarities of local coordination and magnetic properties in single-phase Alx-CrFeCoNi high-entropy alloys

Nano Research ◽

10.1007/s12274-021-3704-5 ◽

2021 ◽

Author(s):

Alevtina Smekhova ◽

Alexei Kuzmin ◽

Konrad Siemensmeyer ◽

Chen Luo ◽

Kai Chen ◽

...

Keyword(s):

Magnetic Properties ◽

Single Phase ◽

Magnetic Circular Dichroism ◽

Surface Region ◽

Face Centered Cubic ◽

X Rays ◽

X Ray ◽

High Entropy ◽

X Ray Absorption ◽

Absorption Edges

AbstractModern design of superior multi-functional alloys composed of several principal components requires in-depth studies of their local structure for developing desired macroscopic properties. Herein, peculiarities of atomic arrangements on the local scale and electronic states of constituent elements in the single-phase face-centered cubic (fcc)- and body-centered cubic (bcc)-structured high-entropy Alx-CrFeCoNi alloys (x = 0.3 and 3, respectively) are explored by element-specific X-ray absorption spectroscopy in hard and soft X-ray energy ranges. Simulations based on the reverse Monte Carlo approach allow to perform a simultaneous fit of extended X-ray absorption fine structure spectra recorded at K absorption edges of each 3d constituent and to reconstruct the local environment within the first coordination shells of absorbers with high precision. The revealed unimodal and bimodal distributions of all five elements are in agreement with structure-dependent magnetic properties of studied alloys probed by magnetometry. A degree of surface atoms oxidation uncovered by soft X-rays suggests different kinetics of oxide formation for each type of constituents and has to be taken into account. X-ray magnetic circular dichroism technique employed at L2.3 absorption edges of transition metals demonstrates reduced magnetic moments of 3d metal constituents in the sub-surface region of in situ cleaned fcc-structured Al0.3-CrFeCoNi compared to their bulk values. Extended to nanostructured versions of multicomponent alloys, such studies would bring new insights related to effects of high entropy mixing on low dimensions.

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Synchrotron X-ray induced acoustic imaging

Scientific Reports ◽

10.1038/s41598-021-83604-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Seongwook Choi ◽

Eun-Yeong Park ◽

Sinyoung Park ◽

Jong Hyun Kim ◽

Chulhong Kim

Keyword(s):

Acoustic Imaging ◽

Signal Frequency ◽

X Rays ◽

Repetition Period ◽

Linear Accelerators ◽

X Ray ◽

X Ray Computed ◽

Medical Linear Accelerators ◽

Ionizing Radiation Exposure ◽

X Ray Absorption

AbstractX-ray induced acoustic imaging (XAI) is an emerging biomedical imaging technique that can visualize X-ray absorption contrast at ultrasound resolution with less ionizing radiation exposure than conventional X-ray computed tomography. So far, medical linear accelerators or industrial portable X-ray tubes have been explored as X-ray excitation sources for XAI. Here, we demonstrate the first feasible synchrotron XAI (sXAI). The synchrotron generates X-rays, with a dominant energy of 4 to 30 keV, a pulse-width of 30 ps, a pulse-repetition period of 2 ns, and a bunch-repetition period of 940 ns. The X-ray induced acoustic (XA) signals are processed in the Fourier domain by matching the signal frequency with the bunch-repetition frequency. We successfully obtained two-dimensional XA images of various lead targets. This novel sXAI tool could complement conventional synchrotron applications.

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An investigation into the existence of zero-point energy in the Rock-Salt Lattice by an X-Ray Diffraction Method

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character ◽

10.1098/rspa.1928.0055 ◽

1928 ◽

Vol 118 (779) ◽

pp. 334-350 ◽

Cited By ~ 41

Keyword(s):

Rock Salt ◽

Diffraction Method ◽

Zero Point ◽

Temperature Factor ◽

X Rays ◽

Zero Point Energy ◽

Chlorine Atoms ◽

Point Energy ◽

X Ray ◽

State Of Rest

In the present paper we shall attempt to collate the results of four separate lines of research which, taken together, appear to provide some interesting checks between theory and experiment. The investigations to be considered are (1) the discussion by Waller* and by Wentzel,† on the basis of the quantum (wave) mechanics, of the scattering of radiation by an atom ; (2) the calculation by Hartree of the Schrödinger distribution of charge in the atoms of chlorine and sodium ; (3) the measurements of James and Miss Firth‡ of the scattering power of the sodium and chlorine atoms in the rock-salt crystal for X-rays at a series of temperatures extending as low as the temperature of liquid air ; and (4) the theoretical discussion of the temperature factor of X-ray reflexion by Debye§ and by Waller.∥ Application of the laws of scattering to the distribution of charge calculated for the sodium and chlorine atoms, enables us to calculate the coherent atomic scattering for X-radiation, as a function of the angle of scattering and of the wave-length, for these atoms in a state of rest, assuming that the frequency of the X-radiation is higher than, and not too near the frequency of the K - absorption edge for the atom.¶ From the observed scattering power at the temperature of liquid air, and from the measured value of the temperature factor, we can, by applying the theory of the temperature effect, calculate the scattering power at the absolute zero, or rather for the atom reduced to a state of rest. The extrapolation to a state of rest will differ according to whether we assume the existence or absence of zero point energy in the crystal lattice. Hence we may hope, in the first place to test the agreement between the observed scattering power and that calculated from the atomic model, and in the second place to see whether the experimental results indicate the presence of zero-point energy or no.

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Anisotropy of X-ray Absorption Cross Section in CeCoGe3 Single Crystal

Crystals ◽

10.3390/cryst11050544 ◽

2021 ◽

Vol 11 (5) ◽

pp. 544

Author(s):

Andrei Rogalev ◽

Fabrice Wilhelm ◽

Elena Ovchinnikova ◽

Aydar Enikeev ◽

Roman Bakonin ◽

...

Keyword(s):

Cross Section ◽

Absorption Cross Section ◽

Linear Dichroism ◽

X Rays ◽

Absorption Cross ◽

X Ray ◽

Measured Absorption ◽

Linearly Polarized ◽

X Ray Absorption ◽

Absorption Edges

Absorption spectra of two orthogonal linearly polarized x-rays in a single CeCoGe3 crystal were measured at the ID12 beamline of the ESRF for the energies near the K-edges of Ge, Co and near the L23 edges of Ce. The X-ray natural linear dichroism (XNLD) was revealed in the vicinity of all the absorption edges, which indicates a splitting of electronic states in a crystalline field. Mathematical modelling in comparison with experimental data allowed the isotropic and anisotropic parts of atomic absorption cross section in CeCoGe3 to be determined near all measured absorption edges. The calculations also show that the “average” anisotropy of the cross section close to the Ge K-edge revealed in the experiment is less than the partial anisotropic contributions corresponding to Ge atoms in two different Wyckoff positions.

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Recent X-ray diffraction studies of muscle

Quarterly Reviews of Biophysics ◽

10.1017/s0033583500000536 ◽

1968 ◽

Vol 1 (2) ◽

pp. 177-216 ◽

Cited By ~ 41

Author(s):

Jean Hanson

Keyword(s):

Electron Microscopy ◽

Diffraction Method ◽

Artificial Muscle ◽

Regular Structure ◽

Normal Activity ◽

Protein Crystal ◽

Natural State ◽

X Rays ◽

X Ray Diffraction ◽

Muscle Biology

An intact living muscle has such a regular structure that it diffracts light or X-rays, thereby providing patterns that contain uniquely valuable information. Interpretation of these patterns is not straightforward, but is helped by light microscopy and electron microscopy, which can often provide similar though less reliable information. At all levels of complexity, from that of the fibrils to that of the molecules, structure in a muscle is orderly. No other natural cell assembly is so suited to study by the diffraction method, and the results obtained in recent years are an outstanding example of how this method can elucidate a biological problem. In contrast to protein crystallography, where the system studied is artificial, muscle can be examined in its natural state, during normal activity. The levels of structure explored as yet in muscle are above that of the atoms in the molecules. Such structure is more commonly investigated by electron microscopy, and the application of the diffraction method to living muscle has provided a valuable check on the preparative artifacts that worry the microscopist. The great complexity of a muscle, as compared with a protein crystal, and the fact that the system is only semi-crystalline, giving a much less detailed diffraction pattern, make the problems of interpretation especially difficult. But a great deal of useful information is available about other properties of muscle and its constituents, and the flourishing state of muscle biology at present is a major factor contributing to the successful application of the diffraction method.

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X–ray absorption fine structure (XAFS) of Si wafer measured using total reflection X–rays

Spectrochimica Acta Part B Atomic Spectroscopy ◽

10.1016/s0584-8547(98)00209-2 ◽

1999 ◽

Vol 54 (1) ◽

pp. 215-222 ◽

Cited By ~ 7

Author(s):

Jun Kawai ◽

Shinjiro Hayakawa ◽

Yoshinori Kitajima ◽

Yohichi Gohshi

Keyword(s):

Fine Structure ◽

Total Reflection ◽

X Rays ◽

X Ray ◽

Absorption Fine ◽

X Ray Absorption ◽

Si Wafer

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A single crystal, linearly polarized Fe 2p X-ray absorption study of gillespite

Mineralogical Magazine ◽

10.1180/002646198547477 ◽

1998 ◽

Vol 62 (1) ◽

pp. 65-75 ◽

Cited By ~ 7

Author(s):

P. F. Schofield ◽

G. van der Laan ◽

C. M. B. Henderson ◽

G. Cressey

Keyword(s):

Single Crystal ◽

Ground State ◽

Branching Ratio ◽

Linear Dichroism ◽

Electronic Charge ◽

Magic Angle ◽

X Rays ◽

X Ray ◽

Peak Structure ◽

X Ray Absorption

AbstractThe Fe 2p X-ray absorption spectra of single crystal gillespite, BaFeSi4O10, show a strong linear dichroism, i.e. a large difference in the absorption when measured with the polarization of the X-rays either parallel or perpendicular to the plane of the FeO4 group. The isotropic spectrum, obtained from measurement at the ‘magic angle’, and the polarization dependent spectra have been compared to atomic multiplet calculations and show an excellent agreement with theory. Analysis of the branching ratio, the linear dichroism, and the detailed peak structure confirms that the 5A1 level is the ground state at room temperature and pressure. The 5B2 level is sufficiently low in energy that a distortion of the electronic charge density, induced by increased pressure, may result in a 5B2 ground state.

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SURFACE SEGREGATION STUDIES OF SOFC CATHODES: COMBINING SOFT X-RAYS AND ELECTROCHEMICAL IMPEDENCE SPECTROSCOPY

MRS Proceedings ◽

10.1557/proc-1217-y07-04 ◽

2009 ◽

Vol 1217 ◽

Author(s):

Lincoln Miara ◽

Louis Piper ◽

Jacob Nathan Davis ◽

Laxmikant Saraf ◽

Tiffany Kaspar ◽

...

Keyword(s):

Single Crystal ◽

Surface Segregation ◽

Elevated Temperatures ◽

Electrochemical Impedance ◽

Lanthanum Manganite ◽

X Rays ◽

Two Phase ◽

X Ray ◽

Cation Migration ◽

X Ray Absorption

AbstractA system to grow heteroepitaxial thin-films of solid oxide fuel cell (SOFC) cathodes on single crystal substrates was developed. The cathode composition investigated was 20% strontium-doped lanthanum manganite (LSM) grown by pulsed laser deposition (PLD) on single crystal (111) yttria-stabilized zirconia (YSZ) substrates. By combining electrochemical impedance spectroscopy (EIS) with x-ray photoemission spectroscopy (XPS) and x-ray absorption spectroscopy XAS measurements, we conclude that electrically driven cation migration away from the two-phase gas-cathode interface results in improved electrochemical performance. Our results provide support to the premise that the removal of surface passivating phases containing Sr2+ and Mn2+, which readily form at elevated temperatures even in O2 atmospheric pressures, is responsible for the improved cathodic performance upon application of a bias.

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