Cause Of Color Research Articles

Coloration of power plant plumes—NO 2 or aerosols?

This article presents an analysis of in situ power plant plume measurements to investigate whether NO 2 or aerosols dominate as the cause of power plant plume coloration. The analysis uses the ratio of NO 2 concentration to the aerosol scattering coefficient ( b sp ) to identify which constituent dominates as the cause of coloration (White, 1980). Presentation of plots of this ratio, NO x, NO 2 and b sp as a function of distance from the plant identifies the dominant cause and controlling mechanisms of coloration as a function of distance from the plant. For aerosols with a mass mean diameter greater than 0.5 μm NO 2 is most frequently the dominant cause of coloration. From plant to plant the frequency that NO 2 dominates as the cause of coloration is independent of the relative amount of paniculate controls used. Instead, the most important variable is the amount of NO 2 at 1 km downwind, presumably reflecting primary NO 2 emissions.

The cause of coloration in Derbyshire Blue John banded fluorite and other blue banded fluorites

SummaryThe cause of coloration of Blue John fluorite from Castleton, Derbyshire, and blue banded fluorites from Ashover, Derbyshire, and Weardale, Co. Durham, has been investigated by a number of techniques, including mass spectrometry, optical spectroscopy, and paramagnetic resonance measurements on natural and irradiated samples. In all respects Blue John is indistinguishable from the other blue banded fluorites. Although traces of hydrocarbons were found in all the natural fluorites including Blue John, they are shown not to be the cause of the colouration. The optical spectra and bleaching behaviour are consistent with colouration by colloidal calcium rather than F-centres. The causes of colour banding are discussed.

The Blue or Blue-Green Coloration of Dried Specimens of Metzgeria

The bluish coloration in dried specimens of Metzgeria is associated with morphology; it occurs in two distinct groups of the genus, one with a ta- pered thallus, the other with dorsal gemmae. The blue or blue-green coloration in dried specimens of Metzgeria was apparently first recorded by Dickson in M. fruticulosa (Dicks.) Evans in 1785, when the species was still included in Riccia. This color characteristic is described in some standard handbooks, for example MacVicar (1926), and scattered records of it also occur in the descriptions of such taxa as Metzgeria violacea (Ach.) Dum., Jungermannia (Metzgeria) furcata L. var. aeruginosa Hook., and Metzgeria disciformis Evans. Few special studies of this problem have been made. Evans (1923) stressed the coloration in a comparison of some Chilean species of Metzgeria. However, the Euro- pean M. fruticulosa has received more attention, notably by Herzfelder (1921), who observed a correlation between coloration of the hepatic and tannin in the bark upon which it grew. It appears that all bluish colorations, whether the whole thallus is deeply bluish or only tinged at the apices, are associated with certain taxonomic or morphological groups of the genus, and from the labels of recent collections we find a much wider range of substrata for such specimens than was earlier suspected. Here I wish to record some comments and notes accumulated during my study of Metzgeria in the hope that a new approach to this problem will eventually be found. Although I am not familiar with fresh material of the species studied, the peculiar coloration seems to appear after drying, and gets deeper as years go by, as can be seen in many very old museum specimens. Few data are available from more recently col- lected materials, although from plants collected in the summer of 1965 Robinson (1967) describes the tips of thalli as usually intensely bluish-green in Metzgeria violacea var. dorsipara, in a key to the Colombian species of Metzgeria. The cause of coloration may possibly be oil-bodies, which are specific cellular in-

Promising new field of study common to solid state physics and the sciences of natural substance

Modern instrumentation and research in electronic structures of minerals and mineral properties and behavior within a wide range of environments and systems has already led to the emergence of the physics of minerals as a practically independent discipline. This discipline, in its present state of development, is based mainly on the quantum analysis of minerals by means of all types and variants of spectroscopy-spectrography and of microscopy which has become adapted to all wavelengths. Such analysis is even now productive of new concepts in mineralogy, geochemistry and physics of geological substance, including newly discovered micromechanisms of isomorphous replacements, redistributions of atoms and electrons in crystal structures, polytypism of layered silicates, and mechanisms or causes of coloration and of defects in minerals. — V. P. Sokoloff.

Colour Variations in Bituminous Coal with Thickness of Sections

THE colour of bituminous coal has been variously attributed to large polynuclear condensed aromatics1–3, free radicals4–6, charge-transfer complexes2,7 and free π-electrons8. The chemical-physical causes of colour remain matters of conjecture and will not be treated here; the optical aspects and simulation of colour in coal will be discussed. Thick sections of coal vitrain are black, or opaque in the visible region of the spectrum. For thin sections, however, the transmitted colour progressively changes from brown to red to yellow with decrease in thickness9,10. The yellow colour is characteristic of the thinnest sections that can be successfully made by the normal procedure. The recent success at this laboratory with the grinding of a thin section to form a wedge suggests that, at thicknesses represented by regions near the tip of the wedge, white light is transmitted; that is, the vitrain is clear and colourless11. Similar variations in colour with thickness are observed for carbonaceous derivatives such as some heavy oils, asphalts and pitches from coal and petroleum. This communication presents an explanation for these colour changes, and the production of identical colour-changes with thickness is demonstrated with pure compounds that are lightly coloured or colourless.

Patination of Cultural Flints

All flints containing unstable impurities are susceptible to patination. The rate of patination varies with many factors: (i) the texture and microstructure of the flint; (ii) its permeability; (iii) the kind, proportion and distribution of impurities; and (iv) environmental factors, such as temperature and soil chemistry. The thickness of the patina varies also with time. Two contrasting types of patina can develop: a chalky white patina and a ferruginous brown patina. Both types are observable primarily as a color change, and study of these types is facilitated by a clear understanding of the causes of color in flint. The color of most flints is the result of repeated refraction and reflection of light at numerous intergranular surfaces, whereby part of the light is internally absorbed and part is reflected back to the observer. The ratio of reflected to absorbed light governs the lightness of the color, or its value. The preferential absorption of certain wavelengths by natural pigments (such as iron oxide and hydrous iron oxide) disseminated through the flint determine the hue of the color. The color changes produced during patination relate to changes in texture and impurity content occasioned by the attack of weathering agents on impurities in the flint. The creation of voids by the dissolution and leaching of carbonates, the loosening of quartz crystallites, and the dispersal of clays all modify the reflectivity of the flint. Chemical changes involving the epigments, their dispersal along intergranular surfaces, or removal by leachig modify both reflectivity and capacity to preferentially absorb. Attempts to correlate patina thickness with age, and thus to use flint patinae chronometrically, have proven unsatisfactory because other factors, whose importance in some cases exceeds that of age, have not been taken into account. The texture and microstructure of flint, its permeability, and the kind, proportion, and distribution of impurities can be evaluated by regular petrographic techniques. Environmental factors can be assumed constant for artifacts from the same types of soil in a given climatic region. Only after allowances have been made for these additional variables does the age-dependence of flint patination become clear.

The cause of color in turquoise.

The cause of color in turquoise.

Dr. Ida Smedley-MacLean

After graduation at the University of Manchester, Dr. MacLean (then Miss Ida Smedley) worked on certain problems in pure organic chemistry under Prof. H. E. Armstrong, investigating inter alia the cause of colour in the dinitrobenzenes. She also acted as demonstrator in chemistry and carried out researches on problems concerning the increase in molecular refractivity of compounds containing a conjugated ethenoid linkage structure. This work resulted in a very interesting communication on the diphenylbutadienes and hexatrienes published in the Journal of the Chemical Society of 1908. Shortly after this early work, Miss Smedley was awarded a Beit Memorial Research Fellowship and went to work in the Biochemical Laboratories of the Lister Institute under Arthur Harden, chemist-in-chief. These laboratories had just been constituted by amalgamation of the Laboratories for Pathological Chemistry under J. B. Leathes (later of Toronto and Sheffield), with the Chemical Laboratory under Harden. One must suppose that about this time Miss Smedley developed that intense and lifelong interest in problems of fat metabolism. Study of fat metabolism and fat synthesis had already been actively pursued at the Institute by J. B. Leathes and the school he there established. It was, however, a field in which few then delved. Dr. Hugh MacLean, who later took a great interest in the study of the lipins, arrived at the Institute as one of Harden's assistants about the same time as Miss Smedley, and their marriage took place in 1913.

The cause of color in precious stones

The cause of color in precious stones

The cause of colour of the blue quartzes of the charnockites of south india and the Champion gneiss and other related rocks of Mysore

The cause of colour of the blue quartzes of the charnockites of south india and the Champion gneiss and other related rocks of Mysore

The Effects of Differences in the Apparent Source of Illumination upon the Shade Assumed by a Flatfish on a Given Background

Previous articleNext article No AccessThe Effects of Differences in the Apparent Source of Illumination upon the Shade Assumed by a Flatfish on a Given BackgroundFrancis B. Sumner and Ancel B. KeysFrancis B. Sumner Search for more articles by this author and Ancel B. Keys Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Volume 2, Number 4Oct., 1929 Article DOIhttps://doi.org/10.1086/physzool.2.4.30152972 Views: 8Total views on this site Citations: 14Citations are reported from Crossref Journal History This article was published in Physiological Zoology (1928-1998), which is continued by Physiological and Biochemical Zoology (1999-present). PDF download Crossref reports the following articles citing this article:Martin Stevens Color Change, Phenotypic Plasticity, and Camouflage, Frontiers in Ecology and Evolution 4 (May 2016).https://doi.org/10.3389/fevo.2016.00051Martin Stevens Evolutionary Ecology: Insect Mothers Control Their Egg Colours, Current Biology 25, no.1717 (Aug 2015): R755–R757.https://doi.org/10.1016/j.cub.2015.07.010Martin Stevens, Alice E. Lown, Louisa E. Wood Color change and camouflage in juvenile shore crabs Carcinus maenas, Frontiers in Ecology and Evolution 2 (May 2014).https://doi.org/10.3389/fevo.2014.00014Martin Stevens, Cheo Pei Rong, Peter A. Todd Colour change and camouflage in the horned ghost crab Ocypode ceratophthalmus, Biological Journal of the Linnean Society 109, no.22 (Apr 2013): 257–270.https://doi.org/10.1111/bij.12039M. Fujimoto, Y. Satoh, F. Morishita Measurement of background‐visual field in flatfishes by CRT display method, Marine Behaviour and Physiology 19, no.44 (Feb 1992): 285–290.https://doi.org/10.1080/10236249209378815M. Fujimoto, T. Arimoto, F. Morishita, T. Naitoh The background adaptation of the flatfish, Paralichthys olivaceus, Physiology & Behavior 50, no.11 (Jul 1991): 185–188.https://doi.org/10.1016/0031-9384(91)90519-TJOY GRAYSON, MALCOLM EDMUNDS The causes of colour and colour change in caterpillars of the poplar and eyed hawkmoths (Laothoe populi and Smerinthus ocellata), Biological Journal of the Linnean Society 37, no.33 (May 2009): 263–279.https://doi.org/10.1111/j.1095-8312.1989.tb01904.xWilliam M. Saidel How to Be Unseen: An Essay in Obscurity, (Jan 1988): 487–513.https://doi.org/10.1007/978-1-4612-3714-3_20W. A. Douglas, W. J. R. Lanzing Colour change and visual cues in the sand flathead, Platycephalus arenarius (Ramsay and Ogilby), Journal of Fish Biology 18, no.66 (Jun 1981): 619–628.https://doi.org/10.1111/j.1095-8649.1981.tb03804.xMichael J. Gentle The Eye and Colour Change in the Minnow ( Phoxinus Phoxinus L), Journal of Experimental Biology 57, no.33 (Dec 1972): 701–707.https://doi.org/10.1242/jeb.57.3.701FRANCIS B. SUMNER QUANTITATIVE CHANGES IN PIGMENTATION, RESULTING FROM VISUAL STIMULI IN FISHES AND AMPHIBIA, Biological Reviews 15, no.33 (Jul 1940): 351–374.https://doi.org/10.1111/j.1469-185X.1940.tb00763.x F. B. Sumner Quantitative Effects of Visual Stimuli Upon Pigmentation, The American Naturalist 73, no.746746 (Sep 2015): 219–234.https://doi.org/10.1086/280832F. A. BROWN, JR. LIGHT INTENSITY AND MELANOPHORE RESPONSE IN THE MINNOW, ERICYMBA BUCCATA COPE, The Biological Bulletin 70, no.11 (Sep 2016): 8–15.https://doi.org/10.2307/1537307Francis B. Sumner, Denis L. Fox A study of variations in the amount of yellow pigment (xanthophyll) in certain fishes, and of the possible effects upon this of colored backgrounds, Journal of Experimental Zoology 66, no.22 (Oct 1933): 263–301.https://doi.org/10.1002/jez.1400660204

LX. On the component parts of light, and the cause of colour

LX. <i>On the component parts of light, and the cause of colour</i>