摘要:

The structure of micellar solutions is determined from X‐ray small‐angle scattering measurements on an absolute scale. The most probable structure is chosen by comparison with spherical cylindrical and lamellar models. This method is applied to two‐component micelles and it is possible to follow the variation of micellar dimensions when the concentration of each component is va

ISSN:1600-5767    

DOI:10.1107/S0021889877012771

出版商:International Union of Crystallography    

年代:1977

数据来源: WILEY

摘要:

The design, construction and operation of a multiple‐counter diffractometer are described. The instrument is used to measure up to five X‐ray reflections from single crystals quasi‐simultaneously: rates of data collection from protein crystals of 250 reflections per hour are ach

ISSN:1600-5767    

DOI:10.1107/S0021889877012783

出版商:International Union of Crystallography    

年代:1977

数据来源: WILEY

摘要:

The crystal and internal structures of the non‐stoichiometric compound TiNx(x= 0.61~0.999, δ‐phase, NaCl type) have been studied by electron diffraction and microscopy. In general, interstitial N atoms produce only short‐range order, but in TiN0.61there is long‐range order after aging at 500°C for one or three months. The ordered structure is tetragonal with lattice parametersa= 4.198 Å2a0(a0= 4.221 Å: lattice parameter of disordered TiN0.61), and belongs to the space groupI41/amdwith the atom positions 8 Ti at 8(e) withz= ¼+0.018, 4 N at 4(a) and 0.88 N at 4(b). The ordered regions develop from small isolated regions and coalesce gradually with aging. The resulting structure contains antiphase and semi‐antiphase domain boundaries with respect to the N atom arrangement. The appearance of the semi‐antiphase domain boundaries is due to the structure being able to have both 41and 43screw axes. The structural difference between TiNxand

ISSN:1600-5767    

DOI:10.1107/S0021889877012795

出版商:International Union of Crystallography    

年代:1977

数据来源: WILEY

摘要:

The separation or overlapping of adjacent subgrain images in Berg–Barrett X‐ray (reflection) micrographs is described for a reasonably general misorientation between the crystal subgrains. The five crystallographic parameters which describe the diffraction experiment also specify, effectively, the direction of the rotation axis for the misorientation, the amount of the angular misorientation, and the relative orientation of the subgrain boundary interf

ISSN:1600-5767    

DOI:10.1107/S0021889877012801

出版商:International Union of Crystallography    

年代:1977

数据来源: WILEY

摘要:

An air‐stream cooling device and a new crystal mounting technique minimize thermal‐gradient problems during precession photography of prote

ISSN:1600-5767    

DOI:10.1107/S0021889877012813

出版商:International Union of Crystallography    

年代:1977

数据来源: WILEY

摘要:

An effective method for greatly reducing the electron exposure of radiation‐sensitive organic or biological specimens while recording their diffraction patterns in a high‐voltage (MeV range) electron microscope is described. It involves recording on double‐coated screen‐type medical X‐ray film and backing it with a luminescent radiographic screen which intercepts the transmitted electrons and emits visible light that exposes the bottom emulsion of the film. Values of sensitivity, resolution, and enhancement ratio are tabulated: the latter values range up to 41. Typical patterns taken withl‐valin

ISSN:1600-5767    

DOI:10.1107/S0021889877012825

出版商:International Union of Crystallography    

年代:1977

数据来源: WILEY

摘要:

The use of electron diffraction in structural studies of fibrous polymers is complicated by the presence of an intense background associated with inelastic scattering. A method of digital processing is described which effectively removes the undesirable features of this background. The method is also applicable in low‐angle X‐ray diffraction stud

ISSN:1600-5767    

DOI:10.1107/S0021889877012837

出版商:International Union of Crystallography    

年代:1977

数据来源: WILEY

摘要:

Some symmetric X‐ray diffraction peaks can be approximated in shape by Pearson type VII distributions:This distribution is Cauchy form= 1, modified Lorentzian form= 2, and Gaussian form= ∞. Some properties of the distribution and some illustrative applications are presen

ISSN:1600-5767    

DOI:10.1107/S0021889877012849

出版商:International Union of Crystallography    

年代:1977

数据来源: WILEY

摘要:

Crystal data are reported for molecular compounds of hexamethylenetetramine with phenol (1:1), resorcinol (1:1), hydroquinone (1:1),o‐cresol (1 : 1),m‐cresol (1:2),p‐chlorophenol (1:2), andp‐bromopheno

ISSN:1600-5767    

DOI:10.1107/S0021889877012862

出版商:International Union of Crystallography    

年代:1977

数据来源: WILEY

摘要:

The structure of the ordered form of the partially ordered cubic: α‐Ga2Se3is based on a tetragonal, body‐centred cell, with space groupI41/acd,a= 23.235 (5),c= 10.828 (2) Å,Z= 48,Dm= 4.91 g cm−3at 30°C. Diffractometer data up to θ ~ 80° from CuKα radiation are given for the β phase with nominal

ISSN:1600-5767    

DOI:10.1107/S0021889877012874

出版商:International Union of Crystallography    

年代:1977

数据来源: WILEY