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In August 1908, a white mob attacked Springfield, Illinois’s Black community, destroying homes and businesses and lynching two Black men. National outrage over the violence helped spur the movement that created the NAACP the following year.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
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In X-ray crystallography, wide-angle X-ray scattering (WAXS) or wide-angle X-ray diffraction (WAXD) is the analysis of Bragg peaks scattered to wide angles, which (by Bragg's law) are caused by sub-nanometer-sized structures.[1] It is an X-ray-diffraction[2] method and commonly used to determine a range of information about crystalline materials. The term WAXS is commonly used in polymer sciences to differentiate it from SAXS but many scientists doing "WAXS" would describe the measurements as Bragg/X-ray/powder diffraction or crystallography.
Wide-angle X-ray scattering is similar to small-angle X-ray scattering (SAXS) but the increasing angle between the sample and detector is probing smaller length scales. This requires samples to be more ordered/crystalline for information to be extracted. In a dedicated SAXS instrument the distance from sample to the detector is longer to increase angular resolution. Most diffractometers can be used to perform both WAXS and limited SAXS in a single run (small- and wide-angle scattering, SWAXS) by adding a beamstop/knife edge.
The WAXS technique is used to determine the degree of crystallinity of polymer samples.[3] It can also be used to determine the chemical composition or phase composition of a film, the texture of a film (preferred alignment of crystallites), the crystallite size and presence of film stress. As with other diffraction methods, the sample is scanned in a wide-angle X-ray goniometer, and the scattering intensity is plotted as a function of the 2θ angle.
X-ray diffraction is a non destructive method of characterization of solid materials. When X-rays are directed at solids they scatter in predictable patterns based on the internal structure of the solid. A crystalline solid consists of regularly spaced atoms (electrons) that can be described by imaginary planes. The distance between these planes is called the d-spacing.
The intensity of the d-space pattern is directly proportional to the number of electrons (atoms) in the imaginary planes. Every crystalline solid has a unique pattern of d-spacings (known as the powder pattern), which is a fingerprint for that solid. Solids with the same chemical composition but different phases can be identified by their pattern of d-spacings.
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In X-ray crystallography, wide-angle X-ray scattering (WAXS) or wide-angle X-ray diffraction (WAXD) is the analysis of Bragg peaks scattered to wide angles, which (by Bragg's law) are caused by sub-nanometer-sized structures. It is an X-ray-diffraction method and commonly used to determine a range of information about crystalline materials. The term WAXS is commonly used in polymer sciences to differentiate it from SAXS but many scientists doing "WAXS" would describe the measurements as Bragg/X-ray/powder diffraction or crystallography. Wide-angle X-ray scattering is similar to small-angle X-ray scattering (SAXS) but the increasing angle between the sample and detector is probing smaller length scales. This requires samples to be more ordered/crystalline for information to be extracted. In a dedicated SAXS instrument the distance from sample to the detector is longer to increase angular resolution. Most diffractometers can be used to perform both WAXS and limited SAXS in a single run (small- and wide-angle scattering, SWAXS) by adding a beamstop/knife edge.
Small-angle X-ray scattering (SAXS) is a small-angle scattering technique by which nanoscale density differences in a sample can be quantified. This means that it can determine nanoparticle size distributions, resolve the size and shape of (monodisperse) macromolecules, determine pore sizes and characteristic distances of partially ordered materials. This is achieved by analyzing the elastic scattering behaviour of X-rays when travelling through the material, recording their scattering at small angles (typically 0.1 – 10°, hence the "Small-angle" in its name). It belongs to the family of small-angle scattering (SAS) techniques along with small-angle neutron scattering, and is typically done using hard X-rays with a wavelength of 0.07 – 0.2 nm. Depending on the angular range in which a clear scattering signal can be recorded, SAXS is capable of delivering structural information of dimensions between 1 and 100 nm, and of repeat distances in partially ordered systems of up to 150 nm. USAXS (ultra-small angle X-ray scattering) can resolve even larger dimensions, as the smaller the recorded angle, the larger the object dimensions that are probed. SAXS and USAXS belong to a family of X-ray scattering techniques that are used in the characterization of materials. In the case of biological macromolecules such as proteins, the advantage of SAXS over crystallography is that a crystalline sample is not needed. Furthermore, the properties of SAXS allow investigation of conformational diversity in these molecules. Nuclear magnetic resonance spectroscopy methods encounter problems with macromolecules of higher molecular mass (> 30–40 kDa). However, owing to the random orientation of dissolved or partially ordered molecules, the spatial averaging leads to a loss of information in SAXS compared to crystallography.
Xenocs is a scientific instrumentation company based in Grenoble, France, providing instruments, software and related services for x-ray characterization of materials, in particular Small Angle X-ray Scattering (SAXS) and Wide Angle X-ray Scattering (WAXS). Xenocs systems are utilized by academic institutions, public research laboratories, and industrial R&D centers for nanoscale characterization and the development of advanced materials. Application segments range from nanomaterials, polymers, food, consumer care, and energy storage to biomaterials and pharmaceuticals. As of September 2020, the Xenocs group reported 75 employees.
Gunne Sax is a retired clothing label owned by Jessica McClintock, Inc., which specialized in formal and semi-formal wear for young women. Eleanor Bailey and Carol Miller co-founded the label in San Francisco in 1967, before partnering with Jessica McClintock in 1969 for a $5,000 investment. The name "Gunne Sax" was associated with the label's roots in prairie, Victorian, and Edwardian-styled designs which drew on many elements popular in late-19th and early-20th-century American fashion such as lace, gingham, and calico. The enterprise was named after the "gunny sack" (hessian/burlap bag) or trim used on some of the earlier dresses. Gunne Sax also manufactured renaissance- and medieval-inspired designs, with empire waistlines and center plackets, and used other historical costume elements such as corset-like laced bodices and puffed sleeves that tightened below the elbow, a style popular in the Tudor period, and then in the 1820s, 1830s and 1890s, known as "leg o'mutton." The earliest labels are known amongst collectors as "black labels". Black labels with the text “Gunne Sax of California” were used only in 1969, making them the most rare to find, though current market value largely depends on the style of the dress. Black labels with the text “Gunne Sax by Jessica” were used from 1969 through the early 70’s. A white “hearts label" was used for a short time following, until, during the mid 1970s and early 1980s, a larger label with scrollwork was put into use. From the 1980s onward, Gunne Sax dresses tended to follow modern prom dress sensibilities, such as tight, strapless bodices and full skirts, favoring fabrics like satin, taffeta, and tulle. In 1999 taffeta was the number one seller paired with matte satin or brocade corsets, with an addition of skirts made in tulle or dotted swiss. Gunne Sax also had a children/young girls' line referred to as Jeunes Filles. In 2023, online retailer ModCloth released a limited collection of Gunne Sax clothing.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →Joe Louis.