omniomni/omni-engineering huggingface dataset:
X-ray scattering techniques. X-ray scattering techniques are a family of non-destructive analytical techniques which reveal information about the crystal structure, chemical composition, and physical properties of materials and thin films. These techniques are based on observing the scattered intensity of an X-ray beam hitting a sample as a function of incident and scattered angle, polarization, and wavelength or energy.

Note that X-ray diffraction is sometimes considered a sub-set of X-ray scattering, where the scattering is elastic and the scattering object is crystalline, so that the resulting pattern contains sharp spots analyzed by X-ray crystallography (as in the Figure). However, both scattering and diffraction are related general phenomena and the distinction has not always existed.  Thus Guinier's classic text from 1963 is titled "X-ray diffraction in Crystals, Imperfect Crystals and Amorphous Bodies" so 'diffraction' was clearly not restricted to crystals at that time.

Scattering techniques

Elastic scattering
 X-ray diffraction, sometimes called Wide-angle X-ray diffraction (WAXD)
 Small-angle X-ray scattering (SAXS) probes structure in the nanometer to micrometer range by measuring scattering intensity at scattering angles 2θ close to 0°.
 X-ray reflectivity is an analytical technique for determining thickness, roughness, and density of single layer and multilayer thin films.
 Wide-angle X-ray scattering (WAXS), a technique concentrating on scattering angles 2θ larger than 5°.

Inelastic X-ray scattering (IXS)
In IXS the energy and angle of inelastically scattered X-rays are monitored, giving the dynamic structure factor .  From this many properties of materials can be obtained, the specific property depending on the scale of the energy transfer. The table below, listing techniques, is adapted from. Inelastically scattered X-rays have intermediate phases and so in principle are not useful for X-ray crystallography. In practice X-rays with small energy transfers are included with the diffraction spots due to elastic scattering, and X-rays with large energy transfers contribute to the background noise in the diffraction pattern.

See also 

 Anomalous scattering
 Anomalous X-ray scattering
 Backscatter
 Materials science
 Metallurgy
 Mineralogy
 Rachinger correction
 Structure determination
 Ultrafast x-ray
 X-rays
 X-ray generator

References

External links

 Learning Crystallography
 International Union of Crystallography
 IUCr Crystallography Online
 The International Centre for Diffraction Data (ICDD)
 The British Crystallographic Association
 Introduction to X-ray Diffraction at University of California, Santa Barbara

Laboratory techniques in condensed matter physics
X-ray crystallography
Materials science
X-ray scattering
Leaf mold. Leaf mold (spelled leaf mould outside of the United States) is the compost produced by decomposition of shaded deciduous shrub and tree leaves, primarily by fungal breakdown in a slower, cooler manner as opposed to the bacterial degradation of leaves.

Description
Leaves shed in autumn tend to have a very low nitrogen content and are often dry. Their main constituents, cellulose and lignin, are two recalcitrant molecules resistant to degradation. Because of this, autumn leaves break down far more slowly than most other compost ingredients which may take a very long time on their own. Specialised biota, such as molds, produce extracellular enzymes which can easily break down those complex plant polymers(cellulose, lignin and hemicellulose) into biologically accessible forms enriching the soil environment.

The importance of this decomposition of the leaves and other  shed plant litter is that their degradation and decomposition forms a critical step in the mineralization of organic nutrients and their  recycling.

Time and process
Fungal decomposition of a heap of leaves in damp temperate climates can take between one and three years to break down into a dark brown fine powdery humic matter. A succession of different fungal species may be involved. A range of micro detritivores are also involved in converting the leaf material into a fine-grained humus, including many isopods, millipedes, earthworms, etc.

Uses
In the natural environment, the decomposition of leaves provides a moist growing medium for young plants and protects the ground from drying out during periods of low rainfall. It is a significant component of soil organic matter, particularly in temperate deciduous woodland. The slow rate of decomposition gradually releases plant nutrients bound up in the leaves back into the environment to be re-used by plants. Autumn leaves are often collected in gardens and farms into pits or containers for the resultant leaf mold to be used later.

Oxygen and moisture are essential for leaf decomposition. Leaf mold is not high in nutrient content but is an excellent humic soil conditioner because its structure and moisture retention provide a good growing medium for seedling roots.

Leaves collected from roads and pavements may be contaminated by pollutants which can become more concentrated as the leaves decompose into a smaller volume

See also
Worm compost
Spent mushroom compost
Recycling

References

External links
BBC Gardening: How to Make Leaf Mould
How to Make Leaf Mould - Greenfingers.com
UK Gardening - How to Make Leaf Mould

Composting
Soil improvers
Permaculture
Sustainable gardening
Sustainable products
Soil
Leaves

ja:腐葉土
Elmer Rees. Elmer Gethin Rees,  (19 November 1941 – 4 October 2019) was a Welsh mathematician with publications in areas ranging from topology, differential geometry, algebraic geometry, linear algebra and Morse theory to robotics. He held the post of Director of the Heilbronn Institute for Mathematical Research, a partnership between the University of Bristol and the British signals intelligence agency GCHQ, from its creation in 2005 until 2009.

Biography 
Rees was born in Llandybie and grew up in Wales. He studied at St Catharine's College, Cambridge gaining a BA before moving on to the University of Warwick, where he completed his PhD in 1967. His thesis on Projective Spaces and Associated Maps, was written under the supervision of David B. A. Epstein.

Rees's career had taken him to University of Hull, the Institute for Advanced Study in Princeton, New Jersey, Swansea University and St Catherine's College, Oxford, before becoming a professor at the University of Edinburgh in 1979, where he remained until retiring from the post in 2005.

He was elected as a fellow of the Royal Society of Edinburgh in 1982. One of his most notable legacies was the establishment of the International Centre for Mathematical Sciences.

Rees was appointed Commander of the Order of the British Empire (CBE) in the 2009 Birthday Honours.

While at the universities of Oxford and Edinburgh, he supervised at least 15 PhD students, including Anthony Bahri, John D. S. Jones, Gregory Lupton, Jacob Mostovoy, Simon Willerton and Richard Hepworth.

Footnotes

External links and references

Senatus Academicus, University of Edinburgh. "Special Minute - Professor Elmer Gethin Rees MA PhD FRSE". Retrieved 2006-10-21.
University of Edinburgh Honorary Degree (24 June 2008)
Heilbronn Institute for Mathematical Research
Elmer Rees 70th birthday conference
70th birthday conference poster

1941 births
2019 deaths
20th-century Welsh educators
21st-century Welsh educators
20th-century Welsh mathematicians 
21st-century Welsh mathematicians
20th-century Welsh scientists
21st-century Welsh scientists
20th-century Welsh writers
21st-century Welsh writers
Algebraic geometers
Academics of the University of Edinburgh
Alumni of St Catharine's College, Cambridge
Alumni of the University of Warwick
Commanders of the Order of the British Empire
Differential geometers
Fellows of the Royal Society of Edinburgh
British topologists
ARC Document Solutions. ARC Document Solutions, Inc. (formerly American Reprographics Company) is a publicly traded company that provides specialized document solutions, with an emphasis on the non-residential segment of the architecture, engineering and construction ("AEC") industry. The firm is headquartered in San Ramon, CA.

Overview
ARC Document Solutions provides onsite managed print services (MPS), archiving and information management (AIM), construction document and information management (CDIM), as well as the sale of technology applications to support these services to more than 90,000 customers.

It operates approximately 170 service centers throughout North America, provides its equipment and services onsite in more than 10,000 customer locations, and services its large enterprise customers with a corporate sales force called Global Solutions.

The company began as a $9 million stand-alone reprographics provider in Southern California in the late 1980s. It has grown to its present size and geographic coverage through the acquisition of more than 140 other companies. It remains the largest company of its kind in the U.S. with more than 2,400 employees.

History
The company began in 1988 as Micro Device, dba "Ford Graphics", a $9 million, privately held Los Angeles-based reprographics company, acquired and managed by ARC's two founders, K. "Suri" Suriyakumar and S. "Mohan" Chandramohan. Following four acquisitions in California, the company was organized as "American Reprographics Company, L.L.C.", a California Limited Liability Corporation, in 1997. Acquired operations generally maintained their original brands in the marketplace to retain local recognition.

Following additional acquisitions that expanded the company's geographical reach into major metropolitan markets in a majority of U.S. states, American Reprographics L.L.C. made its initial public offering in February 2005 and was subsequently listed on the New York Stock Exchange (NYSE) under the ticker symbol "ARP."

Concurrent with the consolidation of its local brands in January 2010, the company's ticker symbol was changed to "ARC". The Delaware corporation name was formally changed to "ARC Document Solutions" in 2012.

ARC has received recognition from Forbes magazine (as one of its "Best 200 Small Companies"), Gartner, MPSA, BERTL, and Océ. In Fiscal 2017, the company's revenue was $406 million.

On November 22, 2024, TechPrint Holdings, Inc. completed the acquisition of ARC.

References

External links
 
 

Companies listed on the New York Stock Exchange
Companies based in Contra Costa County, California
2024 mergers and acquisitions
Reprography. Reprography (a portmanteau of reproduction and photography) is the reproduction of graphics through mechanical or electrical means, such as photography or xerography.  Reprography is commonly used in catalogs and archives, as well as in the architectural, engineering, and construction industries.

Overview
In the United States, the industry is a relatively small industry, with approximately 3000 firms. It comprises entrepreneurial businesses serving predominantly the large- and wide-format reproduction needs of the legal, architectural, engineering, manufacturing, retail, and advertising industries. Average sales volume is about $1.5 million and average employee counts are 20–25 people.

Large-format reproductions are produced with a variety of technologies dependent, in part, on the application of the final product and quantity needed. Examples of typical reproduction methods include: diazo (blueline), electrostatic (xerographic), photographic, laser, and ink jet.

Reproductions can be made from the same size or smaller/larger hard copy originals. Prints can also be computer generated from CADD (computer aided design and drafting) files or from a growing variety of desktop publishing and design software packages.

In addition to addressing the large-format reproduction needs of their customers, reprographers frequently sell reprographic equipment and consumable supplies. Other business services such as mounting and lamination, quick copying, microfilming, scanning and facility management may also be provided.

Typical items produced by reprographers include architectural/engineering blueprints and renderings, indoor and outdoor signage, maps, billboards, backlit displays, trade show graphics, legal and medical exhibits, etc. 
Most of the reprographics firms in the United States belong to the International Reprographics Association (IRgA).

Reprographics is also referred to as "reproprinting".

See also
 Blueprint
 Duplicating machines
 Image scanner
 List of duplicating processes
 Overprinting
 Photocopying
 Whiteprint

External links 
 International Reprographic Association
 Reprographics 101 Blog
 The Reprographics Industry Hall of Fame

Office equipment
Printing processes
Recombination. Recombination may refer to:
Carrier generation and recombination, in semiconductors, the cancellation of mobile charge carriers (electrons and holes)
Recombination (evolutionary algorithm), also called crossover
Genetic recombination, the process by which genetic material is broken and joined to other genetic material
Bacterial recombination
Homologous recombination
Plasma recombination, the formation of neutral atoms from the capture of free electrons by the cations in a plasma
Recombination (chemistry), the opposite of dissociation
Cage effect, a special kind of recombination reaction that appears in condensed phases
Recombination (cosmology), the time at which protons and electrons formed neutral hydrogen in the timeline of the Big Bang
Ferrite. Ferrite may refer to:

 Ferrite (iron), one of the allotropes of iron that is stable at room temperature and pressure, α-Fe
 Ferrite (magnet), a ferromagnetic ceramic material

See also
 
 Ferrite bead, a component placed on the end of a data cable to reduce interference
 Ferrite core, a structure on which the windings of electric transformers and other wound components are formed
 Barium ferrite (BaFe12O19), a ferrimagnetic ceramic material
 Bismuth ferrite, a promising multiferroic material
 Calcium aluminoferrite, , a mineral found in cements
Chlorite. The chlorite ion, or chlorine dioxide anion, is the halite with the chemical formula of . A chlorite (compound) is a compound that contains this group, with chlorine in the oxidation state of +3. Chlorites are also known as salts of chlorous acid.

Compounds

The free acid, chlorous acid HClO2, is the least stable oxoacid of chlorine and has only been observed as an aqueous solution at low concentrations. Since it cannot be concentrated, it is not a commercial product. The alkali metal and alkaline earth metal compounds are all colorless or pale yellow, with sodium chlorite (NaClO2) being the only commercially important chlorite. Heavy metal chlorites (Ag+, Hg+, Tl+, Pb2+, and also Cu2+ and ) are unstable and decompose explosively with heat or shock.

Sodium chlorite is derived indirectly from sodium chlorate, NaClO3. First, the explosively unstable gas chlorine dioxide, ClO2 is produced by reducing sodium chlorate with a suitable reducing agent such as methanol, hydrogen peroxide, hydrochloric acid or sulfur dioxide.

Structure and properties
The chlorite ion adopts a bent molecular geometry, due to the effects of the lone pairs on the chlorine atom, with an O–Cl–O bond angle of 111° and Cl–O bond lengths of 156 pm.
Chlorite is the strongest oxidiser of the chlorine oxyanions on the basis of standard half cell potentials.

Uses
The most important chlorite is sodium chlorite (NaClO2), used in the bleaching of textiles, pulp, and paper. However, despite its strongly oxidizing nature, it is often not used directly, being instead used to generate the neutral species chlorine dioxide (ClO2), normally via a reaction with HCl:

5 NaClO2 + 4 HCl → 5 NaCl + 4 ClO2 + 2 H2O

Health risks 
In 2009, the California Office of Environmental Health Hazard Assessment, or OEHHA, released a public health goal of maintaining amounts lower than 50 parts per billion for chlorite in drinking water after scientists in the state reported that exposure to higher levels of chlorite affect sperm and thyroid function, cause stomach ulcers, and caused red blood cell damage in laboratory animals. Some studies have indicated that at certain levels chlorite may also be carcinogenic.  

The federal legal limit in the United States allows chlorite up to levels of 1,000 parts per billion in drinking water, 20 times as much chlorite as California’s public health goal.

Other oxyanions
Several oxyanions of chlorine exist, in which it can assume oxidation states of −1, +1, +3, +5, or +7 within the corresponding anions Cl−, ClO−, , , or , known commonly and respectively as chloride, hypochlorite, chlorite, chlorate, and perchlorate. These are part of a greater family of other chlorine oxides.

See also
 Tetrachlorodecaoxide, a chlorite-based drug
 Chloryl,

References

Kirk-Othmer Concise Encyclopedia of Chemistry, Martin Grayson, Editor, John Wiley & Sons, Inc., 1985

 
Chlorine oxides
Arsenopyrite. Arsenopyrite (IMA symbol: Apy) is an iron arsenic sulfide (FeAsS). It is a hard (Mohs 5.5–6) metallic, opaque, steel grey to silver white mineral with a relatively high specific gravity of 6.1.  

When dissolved in nitric acid, it releases elemental sulfur.  When arsenopyrite is heated, it produces sulfur and arsenic vapor. With 46% arsenic content, arsenopyrite, along with orpiment, is a principal ore of arsenic. When deposits of arsenopyrite become exposed to the atmosphere, the mineral slowly converts into  iron arsenates.  Arsenopyrite is generally an acid-consuming sulfide mineral, unlike iron pyrite which can lead to acid mine drainage.

The crystal habit, hardness, density, and garlic odour when struck are diagnostic. Arsenopyrite in older literature may be referred to as mispickel, a name of German origin. It is also sometimes referred to as mundic, a word derived from Cornish dialect and which also refers to a copper ore, as well as a form of deterioration in aggregate concrete made with mine tailings.

Arsenopyrite also can be associated with significant amounts of gold. Consequently, it serves as an indicator of gold bearing reefs. Many arsenopyrite gold ores are refractory, i.e. the gold is not easily cyanide leached from the mineral matrix.

Arsenopyrite is found in high temperature hydrothermal veins, in pegmatites, and in areas of contact metamorphism or metasomatism.

Crystallography

Arsenopyrite crystallizes in the monoclinic crystal system and often shows prismatic crystal or columnar forms with striations and twinning common. Arsenopyrite may be referred to in older references as orthorhombic, but it has been shown to be monoclinic.  In terms of its atomic structure, each Fe center is linked to three As atoms and three S atoms.  The material can be described as Fe3+ with the diatomic trianion AsS3−.  The connectivity of the atoms is more similar to that in marcasite than pyrite.  The ion description is imperfect because the material is semiconducting and the Fe-As and Fe-S bonds are highly covalent.

Related minerals
Various transition group metals can substitute for iron in arsenopyrite. The arsenopyrite group includes the following rare minerals:
Clinosafflorite: 
Gudmundite: 
Glaucodot or alloclasite:  or 
Iridarsenite: 
Osarsite or ruarsite:  or

See also
 
 Classification of minerals
 List of minerals

References

External links
 

Iron minerals
Sulfide minerals
Arsenic minerals
Monoclinic minerals
Minerals in space group 14
Lead programmer. In software development, a lead programmer is responsible for providing technical guidance and mentorship to a team of software developers. Alternative titles include development lead, technical lead, lead programmer, or lead application developer.  When primarily contributing a low-level enterprise software design with focus on the structure of the app, e.g. design patterns, the role would be a software architect (as distinct to the high-level less technical role of solutions architect.)

Responsibilities

A lead programmer has responsibilities which may vary from company to company, but in general is responsible for overseeing the work, in a technical sense, of a team of software developers working on a project, ensuring work meets the technical requirements, such as coding conventions, set by the software architect responsible for the underlying architecture. A lead programmer's duties are often "hands on", meaning they typically write software code on a daily basis, assisting their team to meet deadlines and improve the quality of the codebase. They act as a mentor for new or lower-level software developers or programmers, as well as for all the members on the development team, primarily through processes such as pair programming, conducting of  code reviews, promoting good development principles, such as test-driven development, and taking the lead in correcting code defects.

Although the responsibilities are primarily technical, lead programmer also generally serve as an interface between the programmers and management, have ownership of their team's development plans and have supervisorial responsibilities in delegating work. They ensure that sections of software projects come in on time and under budget, and assisting technically with hiring and reviewing performance of staff. Lead programmers also serve as technical advisers to management and provide programming perspective on requirements. Typically a lead programmer will oversee a development team of between two and ten programmers.

A lead programmer typically reports to a principal who manages a number of teams. Technical direction may be provided by a software architect. Where teams follow the waterfall, extreme programming, or kanban approaches, the lead programmer is referred to as an engineering manager, or a software development manager, and collaborates directly with a peer, the product owner, who gathers the customer requirements that the end product must meet. In a true Agile approach, the lead programmer collaborates with a separate position of scrum master, who acts as an intermediary seeking a compromise between business demand (product owner) and team capacity and skillset, e.g. which story tickets from the product backlog will be passed into the next Agile sprint.

References 

 Lead programmer
Software project management
Bytownite. Bytownite is a calcium rich member of the plagioclase solid solution series of feldspar minerals with composition between anorthite and labradorite. It is usually defined as having between 70 and 90%An (formula: ). Like others of the series, bytownite forms grey to white triclinic crystals commonly exhibiting the typical plagioclase twinning and associated fine striations.

The specific gravity of bytownite varies between 2.74 and 2.75. The refractive indices ranges are nα=1.563 – 1.572, nβ=1.568 – 1.578, and nγ=1.573 – 1.583. Precise determination of these two properties with chemical, X-ray diffraction, or petrographic analysis are required for identification.

Occurrence

Bytownite is a rock forming mineral occurring in mafic igneous rocks such as gabbros and anorthosites. It also occurs as phenocrysts in mafic volcanic rocks. It is rare in metamorphic rocks. It is typically associated with pyroxenes and olivine.

The mineral was first described in 1836 and named for an occurrence at Bytown (now Ottawa), Canada. Other noted occurrences in Canada include the Shawmere anorthosite in Foleyet Township, Ontario, and on Yamaska Mountain,
near Abbotsford, Quebec. It occurs on Rùm island, Scotland and Eycott Hill, near Keswick, Cumberland, England. It is reported from Naaraodal, Norway and in the Bushveld complex of South Africa. It is also found in Isa Valley, Western Australia.

In the US it is found in the Stillwater igneous complex of Montana; from near Lakeview, Lake County, Oregon. It occurs in the Lucky Cuss mine, Tombstone, Arizona; and from the Grants district, McKinley County, New Mexico. In the eastern US it occurs at Cornwall, Lebanon County, Pennsylvania and Phoenixville, Chester County, Pennsylvania.

References

 Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., Wiley,

External links

Tectosilicates
Calcium minerals
Sodium minerals
Feldspar
Triclinic minerals
Gemstones
Minerals in space group 2

fr:Bytownite