Rotating-anode X-ray Generator Research Articles

X-Ray Scattering from Nonideal Czochralski Silicon Crystals for High Energy Synchrotron Radiation

Nonideal Czochralski (CZ) silicon crystals were characterized systematically by double-crystal and triple-crystal diffractometry in the Bragg case for high energy synchrotron radiation. The crystals were either annealed at 780°C, 1000°C, and 1170°C, or lapped, with a mean abrasive particle sizes of 13 µm, 25 µm, and 42 µm. Triple-crystal diffractometry was performed at 60 keV of the BL14 vertical wiggler of the Photon Factory and double-crystal diffractometry by use of a Mo rotating-anode X-ray generator. Physical properties of the annealed and lapped crystals were studied quantitatively with respect to mosaic spread and lattice parameter fluctuation.

A micro-XRF spectrometer based on a rotating anode generator and capillary optics

The analytical characteristics of a laboratory-scale micro-X-ray fluorescence spectrometer, based on a rotating anode X-ray generator and capillary optics, are described. Usually, a microbeam 15 μm in diameter, derived from a copper or molybdenum anode operated at 45 kV, is used for sample irradiation. Elemental yields around the 1 count s −1(μg cm −2) −1 level are obtained, corresponding to absolute detection limits for thin samples in the 0.05–1 pg range and to relative MDL levels of 3–10 ppm for thick organic samples. The use of the instrument for studying (trace) element migration in Roman glass and for the nondestructive analysis of decorations on Japanese 18th century porcelain vases is described.

Crystallization and preliminary X-ray diffraction analysis of two lysinal derivatives of Achromobacter protease I.

Two crystal forms of lysinal derivatives of Achromobacter protease I have been obtained. The first, modified by benzyloxycarbonyl-Val-lysinal crystallizes in the monoclinic space group P2(1) with unit-cell dimensions of a = 39.6, b = 71.2, c = 45.6 A and beta = 98.4 degrees. The second, modified by benzyloxycarbonyl-Leu-Leu-lysinal crystallizes in the orthorhombic space group I222 (or I2(1)2(1)2(1)) with unit-cell dimensions of a = 98.7, b = 102.2 and c = 55.8 A. The space groups and the unit-cell dimensions of the present two lysinal derivatives are different to those of the protease and TLCK- modified one. The space group of the protease is P1 with cell dimensions a = 39.53, b = 40.34, c = 43.92 A, alpha = 114.81, beta = 113.75 and gamma = 74.00 degrees and that of the TLCK-modified one is also P1 with cell dimensions of a = 37.30, b = 42.74, c = 48.02 A, alpha = 120.10, beta = 112.81 and gamma = 68.54 degrees. Diffraction to 1.9 A resolution for the Val-lysinal modified crystal and to 2.2 A resolution for the Leu-Leu-lysinal modified crystal has been observed using a rotating-anode X-ray generator. Full structure determinations of these lysinal-modified protease crystals may lead to an understanding of the molecular basis of enzyme-substrate interactions in the catalytic process of this protease.

A point-focusing small angle x-ray scattering camera using a doubly curved monochromator of a W/Si multilayer

A point-focusing small angle x-ray scattering (SAXS) camera using a doubly curved monochromator of a W/Si multilayer has been designed, constructed, and tested. The two radii of curvature of the monochromator are 20 400 and 7.6 mm. The reflectivity of its first-order Bragg reflection for CuKα radiation was calculated to be 0.82, being comparable to that (0.81) of its total reflection. By only 10 s x-ray exposure, scattering from a high-density polyethylene film was detected on an imaging plate (IP). A rotating-anode x-ray generator operated at 40 kV and 30 mA was used. Diffraction from rat-tail collagen has shown that the optical arrangement gives the Bragg spacing up to, at least, 30 nm for CuKα radiation. Combined with IPs, the camera may permit us to carry out time-resolved SAXS measurements for phase behaviors of liquid crystals, lipids, polymer alloys, etc., on conventional x-ray generators available in laboratories.

X-ray Scattering Study of the Melting Transition of a CCl4 Monolayer on Graphite

We have performed an extensive X-ray scattering study of 0.85 monolayer of carbon tetrachloride adsorbed on graphite with a rotating anode X-ray generator. By using a position sensitive detector, we were able to study simultaneously two diffraction peaks during the whole melting transition. A measure of the Debye-Waller correlation function coefficient, η QB , based on peak broadening was performed for the two peaks in the solid regime. The proportionality law between these two coefficients has been verified, with a fairly good agreement and it confirms the quasi-long-range order in the solid. At melting, the coefficient η QB for the first peak is equal to 0.23, a value compatible with previous experimental work and standard theory. The intensities of the diffraction peaks exhibit variations with η QB and coherence length which are in agreement with theoretical predictions in both solid and liquid regimes.

Analysis of a fast crystalline-state reaction by a new diffractometer designed for rapid data collection

A new diffractometer for rapid data collection has been designed and constructed. It is composed of an adjustable, rotating-anode X-ray generator, κ-type, three-circle goniometer, and a multi-layer Weissenberg camera system with imaging plates instead of X-ray film. The quality of the three-dimensional intensity data collected within 2 h is comparable to that obtained by a conventional four-circle diffractometer. With this diffractometer, the mechanism of the ring cleavage of a tricyclooctane derivative, which occurs within several hours of X-ray exposure with retention of the single-crystal form, was clearly established.

Analysis of a fast crystalline-state reaction by a new diffractometer designed for rapid data collection

A new diffractometer for rapid data collection has been designed and constructed. It is composed of an adjustable, rotating-anode X-ray generator, κ-type, three-circle goniometer, and a multi-layer Weissenberg camera system with imaging plates instead of X-ray film. The quality of the three-dimensional intensity data collected within 2 h is comparable to that obtained by a conventional four-circle diffractometer. With this diffractometer, the mechanism of the ring cleavage of a tricyclooctane derivative, which occurs within several hours of X-ray exposure with retention of the single-crystal form, was clearly established.

Development of New In-House Grazing X-ray Reflection System for Analyzing Liquid Surface and Interface

An in-house grazing X-ray reflection (GXR) apparatus has been newly built for studying the liquid surface, and the liquid-solid and liquid-liquid interfaces. This apparatus consists of a high flux rotating anode X-ray generator, pairs of slits for incident and diffracted beams, a channel-cut Ge 440 crystal monochromator and a double-axis diffractometer. This system was tested by measuring X-ray reflectivity profiles from free surface of water or mercury, and the water-mercury interface.

Glass-capillary collimator for distance compensation and partial monochromatization at rotating-anode X-ray generators

Access to the beam ports of rotating-anode X-ray generators is often obstructed by direct-coupled or belt-driven target drives. The construction of an easily adjustable stable glass-capillary collimator is described, which renders possible the unrestricted use of beam ports of these generators. Transmitted intensity and monochromaticity of the primary beam are sufficient for precession photographs of proteins after additional 20 mu m Ni filtering as demonstrated by a precession photograph of hen egg lysozyme. The straight capillary collimator is now a routinely usable low-cost device for each X-ray laboratory.

Performance of a diamond-anvil high-pressure x-ray diffractometer in the Guinier geometry

In this paper, the performance of a novel high-pressure diamond-anvil powder x-ray diffractometer in Guinier geometry is reported. The diffractometer is a combination of a curved quartz-crystal monochromator, a Mao–Bell-type diamond-anvil cell, a flat position sensitive detector, and a Huber goniometer with compound stages to realize this geometry. The incident x-ray beam is from a rotating anode x-ray generator. It is shown that the above experimental arrangement results in an enhanced S/N ratio, improvement in resolution, and reduction of the data-acquisition time. Test results on UAl2 are presented to demonstrate the advantages of the setup in the study of phase transitions at high pressure.

Characterization of Oxide Film Grown on Stainless Steel by a New In-House Grazing Incidence X-ray Scattering (GIXS) Apparatus

An in-house grazing incidence X-ray scattering (GIXS) apparatus has been newly developed for characterizing the surface structure at a microscopic level. This system consists of an 18-kW rotating anode X-ray generator, a flat or channel-cut Ge(111) single crystal monochromator and crossed double-axis diffractometers. Using this new apparatus, the X-ray reflection profiles of chromium oxide films grown on colored stainless steels were measured. The values of critical angle and thickness of films are estimated and the density variation of chromium oxide films is suggested. Surface diffraction profiles from the SUS304 stainless steel oxidized for 240 s at 1073 K in air were also measured in the vicinity of the critical angle with the GIXS geometry. The observed peaks were identified as Cr 2 O 3 , FeCr 2 O 4 and the austenite phase of SUS304. The depth profile has also been discussed from the integrated intensities of both phases of oxide and the stainless steel

In-laboratory stopped-flow extended x-ray absorption fine structure apparatus in the dispersive mode for determination of the structure of short-lived intermediates

We have constructed an in-laboratory stopped-flow extended x-ray absorption fine structure (EXAFS) apparatus by combining laboratory EXAFS equipment in the dispersive mode and a stopped-flow unit with two 150-μm-thick boron nitride windows. The rotating anode x-ray generator with a Mo target was used as an x-ray source. The self-scanning photodiode array was adopted as a position sensitive-linear x-ray detector. In order to obtain a suitable x-ray flux intensity, the accumulation of weak intensities during a short gate time was carried out by repeating the measurements. We have confirmed the performance of our apparatus by repeatedly measuring a number of static EXAFS spectra of 0.20 mol dm−3 aqueous solution of copper(II) sulfate. By use of our newly developed apparatus, we have succeeded in the direct determination of the structure of the reaction intermediate, the heterodinuclear copper(II)/mercury(II) complex, formed in the copper(II) ion incorporation into the homodinuclear mercury(II) complex of 5,10,15,20-tetrakis(4-sulfonatophenyl)porphine.

EXAFS Experiments with High-Power Rotating Anode X-rays

A new laboratory EXAFS facility, which is composed of a dedicated high-power rotating anode X-ray generator and a Johanson-type focusing spectrometer, has been developed. The present X-ray source has provided a line focal spot of about 0.1 mm in width, with a maximum allowable current of 900 mA when operated at a tube voltage of 20 kV. High intensity monochromatic X-rays of more than 106 cps, which are free from higher order harmonics, have been obtained with sufficient energy resolution. The performance of the present EXAFS facility, as well as its application to practical samples, are demonstrated.

Crystallization and preliminary X-ray crystallographic analysis of Mirabilis antiviral protein

Mirabilis antiviral protein is a single-chain ribosome-inactivating protein purified from the tuberous root of Mirabilis jalapa L. We obtained several forms of crystals of the protein by the hanging drop vapor diffusion method, but most of these crystals were not suitable for X-ray crystallography. After refining the growth conditions, crystals of Crystallographic quality were grown in 20-μl droplets of an equi-volume mixture of 1.5% ( w v ) protein solution and a reservoir solution containing 49 to 50% ( w v ) ammonium sulfate and 50 m m-ammonium citrate (pH 5.4) at room temperature. Addition of 2 m m-adenine sulfate reduced twinning and “crystal shower”. The resulting trigonal crystals diffract beyond 2.5 Å resolution using a rotating anode X-ray generator. The space group was determined to be P3 121 or P3 221 ( a = b = 103.9 A ̊ , c = 134.6 A ̊ , α = β = 90 °, γ = 120 °) based on their precession photography of h0 l and hk0 zones. There seems to be three monomers in an asymmetric unit for V M = 2.51 A ̊ 3/Da .

Crystallization and Main-Chain Structure of Neutral Protease from Streptomyces caespitosus1

A neutral protease, i.e., a zinc-containing metalloendoprotease from Streptomyces caespitosus, has been crystallized using acetone as a precipitating agent. The crystals diffract to better than 1.5 A resolution when a rotating anode X-ray generator is used as an X-ray source. Protein phase angles were calculated by the multiple isomorphous replacement method using two heavy-atom derivatives (HgCl2 and CH3HgCl). A 6 A resolution electron density map clearly showed molecular boundaries. Although its amino acid sequence is not known, the folding pattern of the polypeptide chain could be traced on a 2.5 A resolution electron density map. A large cleft, which is located on the molecular surface, was proved to be the active site of the enzyme by structure analyses of inhibitor-complex crystals. The highest electron density peak, which corresponds to the cleft, was assigned to a catalytically essential zinc atom on difference Fourier synthesis between native and EDTA-soaked crystals.

Gas–solid interactions studied by quantitative powder X-ray diffraction analysis

An X-ray diffraction chamber suitable for the simultaneous, quantitative study of solid structure and product composition of stoichiometric and catalytic reactions between solids and gases is described. It may be attached to a conventional or rotating-anode laboratory-scale X-ray generator and to synchrotron sources. Some typical results obtained in the oxidative coupling of methane over lithium nickel oxide at 700 °C are cited (see also the following paper). Rietveld profile analysis of the diffraction patterns recorded using the chamber may be routinely carried out, especially with uniform heterogeneous catalysts.

Design and performance of the multiwire area X-ray diffractometer at the University of Virginia

A multiwire area diffractometer system for measuring X-ray diffraction intensities has been developed and has been functioning as a Biotechnology Resource since 1984. The system consists of four flat multiwire area detectors and associated electronics, rotating-anode X-ray generator, goniostat, monochromator and crystal cooler. An HP 1000 minicomputer has been used to control the goniostat, to collect the data, and concurrently to process it. This computer is being replaced with a MicroVAX 3600. Computer programs, primarily written in Fortran 77, determine and update the orientation of the crystal, integrate the intensities of the reflections, and continually monitor the quality of the output. A statistical determination of systematic errors using lysozyme crystals showed that data accuracy is limited only by counting statistics for σ/\bar I above about 0.02. A compilation of papers published by users based on data obtained at the facility is presented.

Crystallization of serine carboxypeptidases

Crystallization of three different serine Carboxypeptidases has been achieved by the method of hanging-drop vapor diffusion. Serine Carboxypeptidases II from wheat bran and malted barley crystallize isomorphously from polyethylene glycol solutions at room temperature (pH 4 to 7) in space group P4 12 12 or enantiomorph with cell dimensions of a = b = 98.2 A ̊ and c = 209.5 A ̊ . The crystals diffract to about 2.3 Å resolution using rotating-anode X-ray generators. Assuming a dimer of M r 120,000 in the asymmetric unit, V m = 2.1 A ̊ 3/dalton . These crystals appear suitable for structural studies. A genetically engineered serine carboxypeptidase from yeast, which lacks three of four glycosylation sites present in the wild-type, has also been crystallized by vapor diffusion against methylpentanediol at 4 °C, pH 6.4 to 8.0.

A high-resolution multiwire area detector for X-ray scattering

A high-resolution multiwire area detector has been developed for recording X-ray scattering from biological specimens. The detector is 100 × 100 mm 2 and, under the present operating conditions, has a spatial resolution of about 250 μm in both directions. The detector is set up on a double-mirror focusing camera on a rotating anode X-ray generator and has been used in a number of small-angle experiments, two of which are described in this paper.

Synchrotron radiation protein data collection system using the newly developed Weissenberg camera and imaging plate for crystal structure analysis (abstract)

It has been an earnest desire of protein crystallographers to collect fast, accurate, high resolution diffraction data from protein crystals, preferably with exposure time as short as possible. In order to meet this challenge, a new type of Weissenberg camera has been developed for the recording of diffraction intensity from protein crystals using synchrotron radiation. The BL6A2 line has a plane-bending mirror designed by Y. Sato. The optical bench with triangular tilt-cut Si crystal monochromator was designed by N. Kamiya and was installed in the BL6A2 hutch. The Weissenberg camera was set on the 2θ arm of the optical bench. This camera can be used with Fuji Imaging Plate (IP) as an x-ray detector, and the reading out of the image from the IP is carried out by using BA100. The characterization of this system was carried out using the native crystal of chicken gizzard G-actin DNase I complex and its Yb3+, PCMB, indium, and FMA derivatives. Since these crystals are very sensitive for x rays, the resolution limit of the diffraction was 5 Å with a 4-circle diffractometer on a rotating anode x-ray generator (N. Sakabe et al., J. Biochem. 95, 887. This complex was crystallized in space group P2,2,2, with a=42.0, b=225.3, and c=77.4 Å. The data were collected with this system with the 430-mm radius cassette when Photon Factory was operated at 2.5 GeV and 270 mA and the wavelength λ=1.004 Å was chosen. In order to avoid overlapping of diffraction spots, oscillation angle range and coupling constant (degree/mm) were settled on the basis of simulation patterns of diffraction spots up to the maximum resolution to be measured considering the direction of the crystal axes, wavelength, radius of the camera, and mosaicness of the crystal. When the oscillation axis was a axis, the oscillation angle range was selected at either 10° (1°/mm) or 5° (0.5°/mm) depending on the density of reciprocal lattice points along the incident beam, and typical exposure time in each IP was 50 and 25 s, respectively. The exposure was stopped after 10 times oscillation. The total range of 117.5° was recorded on 16 sheets of IP with an overlapping range 0.5°. The data processing was carried out using program weis coded by T. Higashi. Two complete data sets along the a and c axes were collected using two crystals, independently, and the merge R(F2) for native crystal was 0.068. In order to know the feasibility of the data (F+−F−), Patterson maps were calculated with data of each derivative, and heavy atom vectors clearly appeared as prominent peaks in the Harker sections of the Patterson maps of both Yb3+ and PCMB derivatives. The heavy atom positions were obtained from the combinations of different Patterson and different Fourier maps, and were refined by using least-squares techniques. The final figure of merit up to 2.5 Å resolution was 0.61 with 22 700 reflections. The assignment of DNase I part on the electron density maps is progressing using the Nicholson molecular model referring to its structure reported by C. Oefner and D. Suck [J. Mol. Biol. 192, 605 (1986)]. In addition to promising results of ω-aminoacid pyruvate aminotransferase [N. Watanabe et al., Book of abstracts of second Japan-China Bilateral Symposium on Biophysics, p. 83 (1988)], these results support that this data collection system consisting of a new type of Weissenberg camera using SR, Fuji Imaging Plate, BA100, and program weis is one of the fastest and most accurate systems for protein crystallography in use today. We thank the Education Ministry and the Foundations of Yamada, Naito and Toray for the financial support of this project. We are grateful to Dr. K. Namba of ERATO for our use of BA100.