nyuuzyou/wikis huggingface dataset:
Marquetry

== Description ==
A decorative inlaid pattern made from thin layers of wood, ivory, metal, mother-of-pearl, straw, or tortoiseshell, veneered to another surface, usually furniture. Wood marquetry techniques were developed in Antwerp in the early 17th century then imported to France where elaborate luxury pieces were made with very intricate patterns. By the 18th century, workshops in northern Europe and England were known for this specialized technique. The simplest marquetry uses two different color sheets of veneer, temporarily fastened together then cut into a pattern with a fine saw. This created two contrasting panels of identical design (in French called partie and contre-partie, "part" and "counterpart"). Marquetry using colored straw was a specialty of some European spa resorts from the end of the 18th century. 
See also niello, and pietre dure.
== Synonyms and Related Terms ==
inlay; intarsia; marqueterie (Fr.); mfurniturearketierte (Deut.); markieteria (Pol.); marquetería (Esp.); tarsia (It.)
== Additional Images ==
File:SC441328.jpg|thumb|Casket with marquetryMFA# 40.234
File:40.234 detail and X-Ray.jpg|Detail and X-ray of marquetry on MFA# 40.234
==Resources and Citations==
* P.Ramond, R. Bonnefond, 'La marqueterie' Metiers d'art, 27 (no. 26), October 1984.°
* Patrick Edwards, 'Current trends in conservation of marquetry surfaces' Postprints of the Wooden Artifacts Group (AIC), 1997.
* Hermann Kuhn, Conservation and Restoration of Works of Art and Antiquities, Butterworths, London, 1986
* Wikipedia: http://en.wikipedia.org/wiki/Marquetry (Accessed Nov. 9, 2005)
* Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997
* The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998
Category:Materials database
Marquisette

== Description ==
A lightweight, translucent fabric with an open texture. Marquisette is made from cotton, rayon, silk, nylon or rayon in a leno or gauze weave. When prepared with a plain weave, it is often called scrim. Marquisette is used for curtains, dresses, mosquito nets and clothing.
== Synonyms and Related Terms ==
scrim; marquisette (Esp.); lichte gordijnstof (Ned); marquisette (Ned); vitrage (Ned);
Category:Materials database
Mars Plastic eraser

== Description ==
[Staedtler, Germany] A trademark for a white vinyl eraser. First manufactured in 1967, Mars Plastic erasers are composed of polyvinyl chloride with phthalate plasticizers and calcium carbonate fillers. Mars Plastic erasers leave copious small white crumbs that can be removed with vacuuming (Estabrook, 1989). Surface pH measurement of the Mars Plastic erasers gave a neutral value of 7.66 (Estabrook, 1989). They are sulfur-free.
== Risks ==
Decomposes with heat evolving hydrogen chloride fumes
==Resources and Citations==
* E. Estabrook "Considerations of the Effect of Erasers on Cotton Fabric" JAIC 28:79-96, 1989. Link 
* E. J. Pearlstein, D. Cabelli, A. King, & N. Indictor :Effects of Eraser Treatment on Paper" JAIC 22(1):1-12, 1982. Link
* Staedtler product information sheet at: https://www.staedtler.com/us/en/products/pencils-and-accessories/erasers/mars-plastic-526-50-eraser-in-premium-quality-526-50-up/
Category:Materials database
Mars black

== Description ==
Synthetically prepared black iron oxide pigment that was developed in the early 20th century. Mars black is a permanent pigment that has a warm brownish black color. It is a dense, heavy powder and unlike most naturally produced black iron oxide pigments, it is magnetic (the exception is ground magnetite). Mars black absorbs oil readily and unlike lampblack, it is a good drier. Mars black can also be used with watercolors and it does not effloresce when used in mortars and cements. 
See also Mars colors and iron oxide black.
== Synonyms and Related Terms ==
magnetic black iron oxide; Pigment Black 11; Marsschwarz (Deut.); noir de Mars (Fr.); nero di marte (It.); ijzeroxidezwart (synthetisch) (Ned.); negro de marte (Port.); Mapico black
== Risks ==
No significant hazards.
== Resources and Citations ==
* Reed Kay, The Painter's Guide To Studio Methods and Materials, Prentice-Hall, Inc., Englewood Cliffs, NJ, 1983
* Ralph Mayer, A Dictionary of Art Terms and Techniques, Harper and Row Publishers, New York, 1969 (also 1945 printing)
* Michael McCann, Artist Beware, Watson-Guptill Publications, New York City, 1979
* Art and Architecture Thesaurus Online, http://www.getty.edu/research/tools/vocabulary/aat/, J. Paul Getty Trust, Los Angeles, 2000
Category:Materials database
Mars brown

== Description ==
Synthetically prepared dark brown iron oxide pigment. Mars brown is a permanent pigment with good tinting strength and good oil-drying properties. 
See Mars colors.
== Synonyms and Related Terms ==
Pigment Brown 6 and 7; CI 77491 and 77492
== Risks ==
* No significant hazards.
==Resources and Citations==
* Ralph Mayer, A Dictionary of Art Terms and Techniques, Harper and Row Publishers, New York, 1969 (also 1945 printing)
* Michael McCann, Artist Beware, Watson-Guptill Publications, New York City, 1979
Category:Materials database
Mars colors

== Description ==
Originally a brand name in the late 18th century, Mars colors is now the common name used for synthetic iron oxide pigments. Mars colors are made from hydrated iron oxide co-precipitated with alum using lime or potash. The proportion of the mixture controls the degree of color. The product is dried to produce Mars yellow. Other colors, orange, red, black, brown, and violet result from calcining the yellow. Their chemical and physical properties are the same as the natural iron oxides. Mars colors are permanent pigments with good tinting strength and are good driers for oil paints.
== Synonyms and Related Terms ==
Mars yellow; Mars orange; Mars violet; Mars brown; Mars black; Mars red; Mapico pigments; Mars pigments
[[[SliderGallery rightalign|Mars Red (Forbes MFA 85) 785 nm resize.tif~Raman Mars red (MFA)|Mars Yellow (Forbes MFA 242) 785nm (640x445).jpg~Raman yellow (MFA)|PIG85.jpg~XRD]]]
== Risks ==
* No significant hazards.
== Physical and Chemical Properties ==
Lightfast.
==Resources and Citations==
* R. J. Gettens, G.L. Stout, Painting Materials, A Short Encyclopaedia, Dover Publications, New York, 1966
* G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 319
* Ralph Mayer, A Dictionary of Art Terms and Techniques, Harper and Row Publishers, New York, 1969 (also 1945 printing)
* Michael McCann, Artist Beware, Watson-Guptill Publications, New York City, 1979
* R.D. Harley, Artists' Pigments c. 1600-1835, Butterworth Scientific, London, 1982
* Art and Architecture Thesaurus Online, https://www.getty.edu/research/tools/vocabulary/aat/, J. Paul Getty Trust, Los Angeles, 2000
Category:Materials database
Mars orange

== Description ==
Synthetically prepared iron oxide pigment mixed with aluminum oxide. Mars orange is a permanent pigment with good tinting strength and good oil-drying properties. 
See also Mars colors.
== Synonyms and Related Terms ==
Marsorange (Deut.); orange de mars (Fr.); arancio di marte (It.); ijzeroxideoranje (Ned.)
[[[SliderGallery rightalign|Mars orange (Forbes MFA 214) collodion slide, 785 nm resize.tif~Raman (MFA)|f214sem.jpg~SEM|f214edsbw.jpg~EDS]]]
== Risks ==
* No significant hazards.
==Resources and Citations==
* R. Mayer, The Artist's Handbook of Materials and Techniques, Viking Press, New York, 1981.
* R. J. Gettens, G.L. Stout, Painting Materials, A Short Encyclopaedia, Dover Publications, New York, 1966
* Ralph Mayer, A Dictionary of Art Terms and Techniques, Harper and Row Publishers, New York, 1969 (also 1945 printing)
* Michael McCann, Artist Beware, Watson-Guptill Publications, New York City, 1979
Category:Materials database
Mars red

== Description ==
Synthetically prepared red iron oxide pigment. Mars red ranges in colors from scarlet to maroon. It is a permanent pigment with good tinting strength and good oil-drying properties. 
See also Mars colors.
== Synonyms and Related Terms ==
toem; Pigment Red 101; CI 77491; vermelho de Marte (Port.)
== Risks ==
No significant hazards.
[[[SliderGallery rightalign|Mars Red (Forbes MFA 85) 785 nm resize.tif~Raman (MFA)|f85sem.jpg~SEM|f85edsbw.jpg~EDS|Slide9 FC85.PNG~XRF]]]
== Resources and Citations ==
* Ralph Mayer, A Dictionary of Art Terms and Techniques, Harper and Row Publishers, New York, 1969 (also 1945 printing)
* Michael McCann, Artist Beware, Watson-Guptill Publications, New York City, 1979
* R.D. Harley, Artists' Pigments c. 1600-1835, Butterworth Scientific, London, 1982
Category:Materials database
Mars violet

== Description ==
Synthetically prepared violet color iron oxide pigment. Mars violet is a permanent pigment with good tinting strength and good oil-drying properties. 
See Mars colors.
== Risks ==
No significant hazards.
==Resources and Citations==
R. Mayer, The Artist's Handbook of Materials and Techniques, Viking Press, New York, 1981.
* Ralph Mayer, A Dictionary of Art Terms and Techniques, Harper and Row Publishers, New York, 1969 (also 1945 printing)
* Michael McCann, Artist Beware, Watson-Guptill Publications, New York City, 1979
* Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997
* Art and Architecture Thesaurus Online, https://www.getty.edu/research/tools/vocabulary/aat/, J. Paul Getty Trust, Los Angeles, 2000
Category:Materials database
Mars yellow

== Description ==
Synthetically prepared iron oxide pigment. Mars yellow is medium to deep yellow color with good tinting strength and is permanent. It is inexpensive, has good-film forming properties and acts as a drier for oil paints. Synthetic yellow iron oxides are extensively used in the paint industry to produce cream tints with titanium dioxide. 
See also Mars colors.
== Synonyms and Related Terms ==
synthetic yellow ocher; Pigment Yellow 42 and 43; CI 77492; Marsgelb (Deut.); jaune de mars (Fr.); giallo di marte (giallo ossido) (It.); ijzeroxidegeel (Ned.); amarelo de Marte (Port.); yellow iron oxide; iron yellow; yellow oxide of iron; Ferrite; Ferrox; Mapico yellow
== Risks ==
No significant hazards.
[[[SliderGallery rightalign|Mars Yellow (Forbes MFA 242) 785nm (640x445).jpg~Raman (MFA)|PIG242.jpg~XRD|f242sem.jpg~SEM|f242edsbw.jpg~EDS]]]
== Additional Images ==
File:11_Mars_yellow_200X.jpg|Mars yellow at 200x transmitted light
File:11_Mars_yellow_200X_pol.jpg|Mars yellow at 200x polarized light
==Resources and Citations==
* R. J. Gettens, G.L. Stout, Painting Materials, A Short Encyclopaedia, Dover Publications, New York, 1966
* G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 319, 835
* Reed Kay, The Painter's Guide To Studio Methods and Materials, Prentice-Hall, Inc., Englewood Cliffs, NJ, 1983
* Ralph Mayer, A Dictionary of Art Terms and Techniques, Harper and Row Publishers, New York, 1969 (also 1945 printing)
* Michael McCann, Artist Beware, Watson-Guptill Publications, New York City, 1979
* R.D. Harley, Artists' Pigments c. 1600-1835, Butterworth Scientific, London, 1982
* Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997
* Art and Architecture Thesaurus Online, https://www.getty.edu/research/tools/vocabulary/aat/, J. Paul Getty Trust, Los Angeles, 2000
Category:Materials database
Marten hair

== Description ==
The tail hair from any of several small weasel-like animals of the family Mustelidae, such as the Martes martes or Martes zibellina. Martens are commonly found in Russia, Norway, Germany and Switzerland. The bluish-brown hairs are long, strong, and silky. Brushes made from marten hair are similar to sable brushes.
== Synonyms and Related Terms ==
Martes martes (Baum marten); Martes zibellina (black sable, Russian sable); Martes foina (stone or beech marten)
==Resources and Citations==
* Edward Reich, Carlton J. Siegler, Consumer Goods: How to Know and Use Them, American Book Company, New York City, 1937
* Zora Sweet Pinney, 'A Handle on the Terms used for Artists' Brushes', unpublished glossary, 1999
* Wikipedia: http://en.wikipedia.org/wiki/Marten (Accessed Feb. 10, 2006)
Category:Materials database
Martensite

== Description ==
A hard, needle-like crystalline form of carbon steel made by fast cooling. Martensite, named for a German chemist in 1895, is the chief constituent of hardened steel. It is also formed as a decomposition product of austenite. Martensite has been found in ancient materials (Scott, 1991).
== Synonyms and Related Terms ==
martensite (Fr.); Martensit (Deut.); martensiet (Ned.); martensite (Port.)
==Resources and Citations==
* D.Scott, Metallography and Microstructure of Ancient and Historic Metals. Getty Conservation Institute, 1991.
Category:Materials database
Martin's cement

== Description ==
A type of gypsum cement. Martin's cement is made with finely powdered gypsum mixed with potassium carbonate to accelerate cure. It is a hard, white finish plaster.
== Synonyms and Related Terms ==
gypsum cement
==Resources and Citations==
* G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 174
* Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
Category:Materials database
Masanobu, Large Perspective View of the Interior of Echigo-ya in Suruga-chô, 11.13343

Large Perspective View of the Interior of Echigo-ya in Suruga-chô (Suruga-chô Echigoya gofukuten ô-ukie)
「駿河町越後屋呉服店大浮画」
Okumura Masanobu (1686–1764)
Publisher: Okumuraya Genroku
Edo period about 1745 (Enkyô 2)
for more information see:
MFA Online Collections Database
== Summary == 
Analysis point	Image	Method	Results
Pt 1 	 	 	red lead, vermilion
Pt 2 	 	 	red lead, vermilion
Pt 3 	 	 	iron oxide red, red lead
Pt 4 	 	 	gamboge
Pt 5 	 	 	flavonoid
Pt 6 	 	 	red lead, flavonoid
Pt 7 	 	 	madder
Pt 8 	 	 	inconclusive
Pt 9 	 	 	safflower
Note: The center of the circle is point of analysis.
Category:Okumura Masanobu (奥村政信) 1686–1764
Category:Flavonoids: Ukiyo-e colorant
Category:Gamboge: Ukiyo-e colorant
Category:Iron Oxide Red: Ukiyo-e colorant
Category:Madder: Ukiyo-e colorant
Category:Other Reds: Ukiyo-e colorant
Category:Red lead: Ukiyo-e colorant
Category:Safflower: Ukiyo-e colorant
Category:Vermilion: Ukiyo-e colorant
Masanobu, Perspective Picture of a Triptych of the Three Evening Poems, by the Authentic Originator of Color Printing and Perspective Prints, 11.13344

Perspective Picture of a Triptych of the Three Evening Poems, by the Authentic Originator of Color Printing and Perspective Prints (Uki-e sanseki sanpukutsui, benizuri-e narabi ni uki-e kongen shômei)
「浮絵三夕三幅對　紅摺並浮絵根元正名」
Okumura Masanobu (1686–1764)
Publisher: Okumuraya Genroku
Edo period about 1742–44
for more information see:
MFA Online Collections Database
== Summary == 
Analysis point	Image	Method	Results
Pt 1 	 	 	flavonoid
Pt 2 	 	 	gamboge
Pt 3 	 	 	red lead
Pt 4 	 	 	iron oxide red
Pt 5 	 	 	safflower?
Pt 6 	 	 	brass
Pt 7 	 	 	inconclusive
Note: The center of the circle is point of analysis.
Category:Okumura Masanobu (奥村政信) 1686–1764
Category:Brass: Ukiyo-e colorant
Category:Flavonoids: Ukiyo-e colorant
Category:Gamboge: Ukiyo-e colorant
Category:Iron Oxide Red: Ukiyo-e colorant
Category:Red lead: Ukiyo-e colorant
Category:Safflower: Ukiyo-e colorant
Masking paper

== Description ==
Any paper that is used to cover or hide another surface. Masking paper is commonly used to prevent spray paint from reaching regions that are not selected for painting.
==Resources and Citations==
* G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 271
* The Dictionary of Paper, American Paper Institute, New York, Fourth Edition, 1980
Category:Materials database
Masking tape

== Description ==
A pressure-sensitive tape developed in 1925 by 3M to help define lines during the spray painting of two-tone automobiles. Masking tape is composed of a creped strip of kraft paper that has an adhesive coating on one side. Originally a rubber-based adhesive was used, but most masking tapes now have an acrylic adhesive. In addition to paint applications, masking tape has been used for binding, sealing and mending. Masking tape is designed to remove cleanly from a surface with no damage or residue, but it can be difficult to remove if left on for more than a few days.
== Synonyms and Related Terms ==
ruban-cache (Fr.); ruban protecteur (Fr.); bande-cache (Fr.);
==Resources and Citations==
* Pam Hatchfield, Pollutants in the Museum Environment, Archetype Press, London, 2002
* Ceramics and Glass Conservation Section, List of Workshop Materials, The British Museum, London
* The Dictionary of Paper, American Paper Institute, New York, Fourth Edition, 1980
* Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997
* A Glossary of Paper Conservation Terms, Margaret Ellis (ed.), Conservation Center of the Institute of Fine Arts, New York City, 1998
* The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998
* Art and Architecture Thesaurus Online, https://www.getty.edu/research/tools/vocabulary/aat/, J. Paul Getty Trust, Los Angeles, 2000
Category:Materials database
Masonry

== Description ==
Construction with stone, brick, or rubble. Ancient masonry examples used irregular blocks of stone set together without mortar. Most modern masonry uses mortar or cement in the joints. Rubble masonry uses field stones or irregular quarried stones. Ashlar masonry used regularly cut square or rectangular quarry stones set with fine, close joints. Simulated masonry includes numerous precast products that imitate the appearance of stones with mortar joints.
== Synonyms and Related Terms ==
maçonnerie (Fr.); alvenaria (Port.); stonework; brickwork;
==Resources and Citations==
* G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 173
* Dictionary of Building Preservation, Ward Bucher, ed., John Wiley & Sons, Inc., New York City, 1996
* Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997
* The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998
* Art and Architecture Thesaurus Online, https://www.getty.edu/research/tools/vocabulary/aat/, J. Paul Getty Trust, Los Angeles, 2000
Category:Materials database
Masonry cement

== Description ==
A premixed cement used for mortar of masonry walls. Masonry cements are generally more workable than normal portland cement. They usually contain a portland cement base with hydrated lime, crushed limestone, diatomaceous earth or granulated slag to aid in spreading.
== Synonyms and Related Terms ==
masonry cement
==Resources and Citations==
* G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 173
* Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
* The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998
* Ivan Myjer, contributed information, 1998
Category:Materials database
Mass spectrometry

== Description ==
In mass spectrometry, an instrument is used to produce ions from molecules. Two common ways of doing this are bombarding the sample either with a beam of electrons (electron ionization) or with small molecules such as methane (chemical ionization). The initial ion, called the molecular ion, often undergoes fragmentation into a pattern of smaller molecular weight ions. The ions are separated according to their mass-to-charge ratio and their relative intensities, producing a mass spectrum. In a quadrupole instrument, the ions produced in the source enter a high-vacuum area between rod electrodes maintained at opposite polarity. The application of varying radio frequencies and DC and AC voltages allows only ions with specific mass-to-charge ratios to be ejected to the detector. In ion trap mass spectrometers, the ionization and storage of ions occur in the same location. The ion trap electrodes create a three-dimensional electric field that holds the ions. Application of an appropriate radio frequency voltage is then used to eject ions with specific mass-to-charge ratios. Mass spectrometers frequently serve as detectors for gas or liquid chromatographs.
The description above obtained from the National Gallery of Art, Scientific Research: Glossary of Conservation Terminology
== Synonyms and Related Terms ==
MS; spectrométrie de mass (Fr.)
==Resources and Citations==
* Wikipedia: Mass spectrometry
Category:Materials database
Massicot

== Description ==
A heavy yellow powder composed of lead monoxide. Massicot is the name used for both the native mineral as well as the lead monoxide product made by heating lead carbonate to 300C. Litharge, another crystalline form of lead monoxide, is the oxidized product of molten lead that has been stirred or atomized to incorporate air then cooled and ground to form the yellow powder. Litharge tends to be slightly more orange than massicot due to the presence of small amounts of red lead oxide. Lead monoxide has been used as a drier in oil and as a low-fire flux in making ceramics and glass. It was also used as a yellow pigment in paints and glazes. Thin layers of lead monoxide produce iridescent colors on brass and bronze. It has also been used as a filler for rubber and to produce artificial tortoiseshell and horn.
[[[SliderGallery rightalign|MassicotUCL.jpg~Raman]]]
== Synonyms and Related Terms ==
lead monoxide; masicote (Esp.); litargirio (Esp.); massicot (Fr.); massicote (Port.); plumbous oxide; plumbic ocher; fiallolino; giallorino; Flemish yellow; masticot; lead ocher
== Risks ==
* Toxic by inhalation or ingestion. 
* Skin contact may cause irritation or ulcers. 
* Carcinogen, teratogen, suspected mutagen.
* Millipore Sigma: SDS
== Physical and Chemical Properties ==
* Soluble in acetic acid, dilute nitric acid and alkalis. Insoluble in water and ethanol. 
* Turns gray on exposure to sulfur fumes and light.
Composition 	PbO
CAS 	1317-36-8
Melting Point 	888 C
Density 	9.40-9.53 g/ml
Refractive Index	2.51; 2.71; 2.61
== Resources and Citations ==
* R. J. Gettens, G.L. Stout, Painting Materials, A Short Encyclopaedia, Dover Publications, New York, 1966 Comment: Yellow lead monoxide has been found in sites from predynastic times in Egypt....Pliny described the preparation of both litharge and massicot....In modern times, massicot is not used as a paint pigment
* Ralph Mayer, A Dictionary of Art Terms and Techniques, Harper and Row Publishers, New York, 1969 (also 1945 printing) Comment: Massicot was used as an artists pigment from the 15th c. to the end of the 18th . or the early 19thc
* R.D. Harley, Artists' Pigments c. 1600-1835, Butterworth Scientific, London, 1982
* Thomas B. Brill, Light Its Interaction with Art and Antiquities, Plenum Press, New York City, 1980 Comment: Massicot is essentially absent from paintings after the thirteenth century but was used in very early times (400BC in Egypt)...
* The Dictionary of Art, Grove's Dictionaries Inc., New York, 1996 Comment: "Pigments"
* Wikipedia: http://en.wikipedia.org/wiki/Massicot (Accessed Feb. 2, 2006)
* Dictionary of Building Preservation, Ward Bucher, ed., John Wiley & Sons, Inc., New York City, 1996
* G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 445
* Susan E. Schur, Conservation Terminology: A review of Past & Current Nomenclature of Materials, Technology and Conservation, Spring (p.34-39); Summer (p.35-38); Fall (p.25-36), 1985
Category:Materials database