Ruby Color Research Articles

Beauty and the beast

Pernicious anemia was described 100 years before formulation of liver extracts to correct the fatal disorder. Later, the elucidation of the crystalline structure of vitamin B12 (cobalamin) and recognition of its beautiful ruby color resulted in its description as “nature's most beautiful co-factor.”1 These discoveries led to 2 Nobel prizes, for Minot, Murphy, and Whipple in 1934 (Physiology or Medicine), and for Hodgkins in 1964 (Chemistry), only the third woman to win a Nobel in Chemistry. Although low B12 levels had long been known to cause neurologic disease, Lindenbaum and colleagues2 uncovered B12-responsive neuropsychiatric conditions in persons without macrocytic anemia, some with normal circulating B12 levels (>200 pg/mL or >150 pmol/L). Vitamin B12 is an essential cofactor for the activation of methionine into S-adenosyl methionine (SAM), the primary methyl donor for most neuronal methylation reactions, including synthesis of catecholamine neurotransmitters, proteins, nucleic acids, phospholipids, and myelin. Homocysteine is an essential intermediary metabolite in this pathway and elevated plasma total homocysteine (tHcy) invariably accompanies low B12 levels. Beginning in the 1990s, a series of observational case-control and cohort studies associated elevated tHcy with an increased risk of stroke, cognitive decline, and dementia, including Alzheimer disease (AD). These associations were generally more robust than those …

Sound production in Calliptamus barbarus Costa 1836 (Orthoptera: Acrididae: Catantopinae)

Calliptamus barbarus Costa 1836 is an acridid species whose hind femora display chromatic polymorphism that may be of ruby colour with three bold and separate femoral spots, or pale orange, with only one large femoral spot. Since both bio forms (either with three (3S) or with one (1S) spot) appear to be segregated, and their sounds constitute an intra-specific recognition system during mating, the sounds emitted by both groups were studied in order to identify any differences between them. It was observed that the sound is produced by mandible friction in both males and females. The temporal characteristics of the acoustic emissions of the males of both bio forms showed significant differences under all conditions. In females, some differences in frequency and in temporal characteristics were also detected. Likewise males, the syllable length and the number of emitted pulses are greater in the 1S than in the 3S form. Together with other differences, these observations suggest a true separation between these bio forms, with a reproductive isolation that will probably lead to a speciation process.

Optical Spectra of Copper‐Doped Zn‐Phosphate Glasses

Copper‐containing, binary, Zn‐phosphate glasses were melted under reductive conditions. The profile of their optical spectra and their color change drastically when the ZnO content of the host is modified. An increase in the host's ZnO concentration tilts the copper oxidation state's equilibria toward the reduced species Cu+ and Cu0. In hosts containing more than 52 mol% ZnO, the Cu0 aggregates precipitate upon melt cooling to form ruby glasses. The ruby color also appears in glasses including 50 mol% ZnO, after thermal treatments. The effect of ZnO increase, in the composition of binary Zn‐phosphate glasses, on the redox equilibria of a copper dopant, is inverse to that caused by increase of Na2O content in the case of Na‐phosphate hosts.

From the green color of eskolaite to the red color of ruby: an X-ray absorption spectroscopy study

The best known cause for colors in insulating minerals is due to transition metal ions as impurities. As an example, Cr3+ is responsible for the red color of ruby (α-Al2O3:Cr3+) and the green color of eskolaite (α-Cr2O3). Using X-ray absorption measurements, we connect the colors of the Cr x Al2−x O3 series with the structural and electronic local environment around Cr. UV–VIS electronic parameters, such as the crystal field and the Racah parameter B, are related to those deduced from the analysis of the isotropic and XMCD spectra at the Cr L2,3-edges in Cr0.07Al1.93O3 and eskolaite. The Cr–O bond lengths are extracted by EXAFS at the Cr K-edge in the whole Cr x Al2−x O3 (0.07≤x< 2) solid solution series. The variation of the mean Cr–O distance between Cr0.07Al1.93O3 and α-Cr2O3 is evaluated to be 0.015 A (≈1%). The variation of the crystal field in the Cr x Al2−x O3 series is discussed in relation with the variation of the averaged Cr–O distances.

Origin of the different color of ruby and emerald

Origin of the different color of ruby and emerald

Ab initio calculation of the Cr K-edge in α-Al2O3:Cr3+

The red color of ruby (α-Al2O3:Cr3+) is assigned to transitions between 3d states of the chromium ion. A precise description of the structural and electronic environment of the Cr3+ ion in its slightly distorted octahedral site (C3 symmetry) is needed to understand the cause of the color. We have analysed the Cr K-edge in Cr3+ with a reciprocal space approach that allows the computation of self-consistent spin polarized charge density for large unit cells, beyond the traditional “muffin-tin” approximation. Structural and electronic information is deduced from the calculation.

AVALIAÇÃO DA CV. CABERNET FRANC PARA ELABORAÇÃO DE VINHO TINTO

A uva Cabernet Franc, originária da região de Bordeaux, França, foi introduzida no Rio Grande do Sul através da Estação Agronômica de Porto Alegre. É utilizada para a elaboração de vinho tinto para ser consumido jovem, embora apresente aptidão para envelhecer. Face a sua importância, conduziu-se este trabalho com o objetivo de determinar as características agronômicas e enológicas da uva Cabernet Franc para elaboração de vinho tinto. Para isso, realizaram-se estudos para caracterizar o cacho, o mosto e o vinho tinto nas safras de 1987 a 1994. Os resultados obtidos evidenciaram que a cv. Cabernet Franc tem cacho médio, formado por bagas pequenas. O mosto possui teores de açúcar e de acidez adequados para vinificação. O vinho apresenta elevado teor de K e de álcoois superiores. No aspecto sensorial, apresenta cor vermelho-rubi, com reflexos violáceos quando jovem, e de intensidade variável em função das safras vitícolas. No olfato, apresenta aroma com notas vegetais e frutadas, que lembram pimentão e frutas vermelhas, respectivamente. Gustativamente, o vinho apresenta boa estrutura, equilíbrio e personalidade marcante.

Origin of the Red Color of Satsuma Copper‐Ruby Glass as Determined by EXAFS and Optical Absorption Spectroscopy

The origin of the ruby color of Satsuma glass, a famous copper‐ruby glass produced in Japan in the mid‐19th century, has been examined by electron microprobe analysis (EPMA), X‐ray absorption fine structure (XAFS), and optical absorption spectroscopy analyses. CuK XAFS analysis reveals that the major component of copper in the ruby glass consists of Cu(I) ions in the glass structure. This species is distinct from Cu2O (cuprite), which we conclude is not responsible for the ruby color. Optical absorption spectra measured at 300 and 77 K clearly distinguishes the absorptions due to the colloidal particles of metallic copper and Cu2O. It is concluded that the trace amount of copper in the ruby glass, which is below the detection limit of the EPMA and XAFS techniques, exists as metallic copper particles of nanometer size and is responsible for the ruby‐red appearance of the Satsuma glass.

The influence of wine additives on colour and colour quality of young red wine

Zweigelt 1987, a typical Austrian wine treated with wine additives such as sulphur dioxide,l-ascorbic acid and sorbic acid was stored for 77 days. All characteristic wine components were analysed during the storage period. Only changes in colour could be detected. The changes in the amount of anthocyanins and anthocyanidin chlorides were analysed. The results show that Zweigelt 1987 mixed with wine additives such asl-ascorbic acid or sorbic acid resulted in a larger loss in colour than untreated wine. The changes could be measured photometrically but they were invisible to the naked eye. Appropriate use of wine additives did not appear to deterioriate the ruby colour of young red wine during the period tested.

淡いルビー色梨ワインの醸造

Some varieties of Japanese pear were proved to give bright, light ruby colored pear wines with lower acidity and relatively flat taste. Further study to obtain better ruby color gave the following results:1) The pear varietyShinsuiwas the most suitable variety.2) As to fermentation conditions, the best color was obtained when theShinsuipear must was fermented by a wine yeast strain, S. cerevisiaeK-3 at 15°.3) The ruby color was littlea ffected by the levels of potassium pyrosulite (50-150 mg/l) which was added into the pear musts before fermentation.

Application of aromatic red rice bran to rice wine brewing: Studies on red rice wine brewing (Part 2)

Rice wines were made from various kinds of rice and/or rice brans. The aromatic red rice wine made from unpolished aromatic red rice ( Oryza sativa var. Indica, Tapol), having a wine-like fruity aroma and sour taste, showed the highest quality, while rice wine made from polished aromatic red rice showed a lower quality in an organoleptic test and gas chromatographic analysis. Rice wines made from the bran of aromatic red rice and red rice, the waste product of the polishing process in Sekihan cooking, contained 2.5 times greater amounts of higher alcohols and 3.5–5.0 times greater amounts of volatile esters than rice wines made from the bran of glutinous and nonglutinous rices. Thus, the bran fraction of aromatic red rice was essential for the formation of a ruby color and fruity aroma. Various amounts of aromatic red rice bran were mixed with polished aromatic red rice and also applied to rice wine brewing. Rice wine made from 10 g of bran and 21 g of polished aromatic red rice showed the best quality according to the organoleptic test and gas chromatographic analysis. The optimal ratio of bran to polished rice as a raw material for rice wine brewing was almost equal to that of native unpolished rice. Aromatic red rice bran was further mixed with polished glutinous rice or nonglutinous rice and applied to rice wine brewing. The resulting rice wines had the characteristic ruby color and fruity aroma, just the same as the aromatic red rice wine made from native unpolished aromatic red rice. Thus, not only native unpolished aromatic red rice, but also its bran, could be applied directly and economically to rice wine brewing without the need for any complicated process.

Studies on the development process of gold ruby glasses

The relationship between the size of Au crystallites and the temperature of heat treatment in the development process of gold ruby glasses has been studied by small-angle X-ray scattering and transmission electron microscope. Glasses were heat-treated at temperatures from 550°C to 900°C. But the color can only be developed at temperatures higher than 600°C. The particle size of gold crystallites is about 340 Å at this moment and increases with temperature, the final particle size of Au crystallites being about 550 Å, the size at 900°C is almost identical with that at 700 °C. The particle size distribution of Au crystallites in gold ruby glasses will be more concentrated with the increase of temperature. Once the ruby color emerges, change in color induced by further heat treatment will be extremely small.

Synthesis of zinc-free ruby glasses

The effect on the color of a soda lime silicate glass of a single constant composition of the addition of coloring and reducing agents in different ratios was studied. As the control glass, the authors used the composition (mass composition /sup 0/): Sio/sub 2/, 75; Zno, 9.3; Na/sub 2/O, 15.7; the coloring agents were added to 100 parts of batch (g/100g of glass) as follows: CdS, 1.4 and Se, 0.35. A study of the effect of color of the glass of the addition of Group II metal oxides was carried out on glasses with an identical molar concentration of oxides: SiO/sub 2/, 75%; MeO, 9.3%; and Na/sub 2/O, 15.7%. In glasses of the SiO/sub 2/-MeO-Na/sub 2/O system (where MeO is MgO, CaO, SrO, BaO, or CdO) a ruby color was obtained when there was a significant increase in the amount of Se added to the batch (by comparison with the Zn containing compositions) or with roughly the same amounts of Se but with the addition of reducing agents to the batch.

Ruby Glass Produced in a Pt‐Au Crucible

The observation that a ruby color is produced in soda‐lime glass doped with SnO2, melted in a PtSAu crucible, and reheated is described and briefly discussed.

Study of the colouring process in copper ruby glasses by optical and EPR spectroscopy

The mechanism responsible for the development of the ruby colour in silica glasses containing copper have been investigated by means of optical and EPR spectroscopy. During the striking treatment, the evolution of the concentration of Cu+ and Sn2+ has been followed through their luminescence bands, whereas the Cu2+ concentration has been monitored by the EPR spectra. To account for the data, a model for the colouring which involves two simultaneous redox reactions: (i)2Cu+→Cu2++Cu0 (ii)2Cu2++Sn2+→2Cu++Sn4+ has been proposed. According to it, the role of tin is to act as a redox buffer to regenerate Cu+, therefore favouring the coalescence of Cu2O colloids.

Change in Rind, Flesh, and Juice Color of Blood Oranges Stored in Air Supplemented with Ethylene or in Oxygen‐Enriched Atmospheres

ABSTRACTRuby, Tarocco, and Sanguinello blood oranges were stored 4 wk at 15°C in flowing air, 20 ppm ethylene in air, 40% O2+ 60% N2, or 80% O2+ 20% N2, followed by storage in air. Ethylene caused rind color of Ruby and Tarocco oranges to become deeper orange while 80% O2 caused rind of Ruby and Sanguinello oranges to be paler orange than when stored in other atmospheres. Ethylene deepened red color of the flesh and juice of Ruby and Tarocco oranges, but high O2 more intensely deepened the red color of flesh and juice of all three cultivars. Total soluble solids content, total acidity, or pH of the juice was not affected. Fruit stored in the ethylene atmosphere developed off‐flavor.

Small‐Angle X‐Ray Scattering Analysis of Nucleation in Glass: II, Selenium Ruby Glasses

Nucleation studies were conducted on several selenium ruby glasses, of different colorant concentrations, using the technique of small‐angle X‐ray scattering. The glass rnicrostructure increased from homogeneous to 6‐nm (60‐Å) precipitating particles as the colors changed from colorless through yellow and orange to red. The glasses showed little difference in particle morphology despite differences in color, supporting the explanation of ruby color formation as due to energy band‐gap phenomena. Matrix intensities, particle volume concentrations, and interfacial surface areas were also determined.

Thermodynamics of Copper-Oxygen System Dissolved in a Glass—Relation to Copper Ruby Formation

The Cu2O(glass)-Cu(glass) equilibrium was studied in 25Na2O, 10Al2O3, 65B2Os glass at varied partial pressures of oxygen (pO2=10−12 to 10−17 atmosphere) and temperatures in contact with solid metallic copper. On heat-treatment, the best ruby was formed in glass melted at pO2=10−14 atmosphere, at higher pO2's no ruby colour developed, and at pO2 ≤10−15 atmosphere the glass produced progressively poorer rubies. Using the thermodynamic data estimated for the Cu2O(glass)-Cu(glass) system, possibilities for the precipitation of Cu (solid) and Cu2O (solid) are discussed. It is concluded that Cu2O (solid) is primarily responsible for the bright red ruby colour in this glass.

ChemInform Abstract: THERMODYNAMICS OF THE SYSTEM CU‐O AND RUBY FORMATION IN BORATE GLASS

AbstractDie Gleichgewichte CuO‐Cu2O und Cu2O‐Cu in der glasigen Lösung werden in 30 Na2O·70 B2O3‐ und 25 Na2O·10 Al2O3·65 B2O3‐Gläsern bei verschiedenen O2‐Partialdrücken und Temperaturen untersucht.

Thermodynamics of the System Cu‐O and Ruby Formation in Borate Glass

The CuO‐Cu2O and Cu2O‐Cu equilibria in glass solution were studied in 30Na2O 70B2O, and 25Na2O · 10Al2O3· 65B2O3 glasses at varied partial pressures of O2 and temperatures. The CuO‐Cu2O equilibrium was studied in a Pt crucible atpO2= 1 to 0.05 atm with ∼0.5 wt% Cu; the Cu2O‐Cu equilibrium was studied in Cu crucibles at much lower pO2's (10−14 to 10−17 atm), where no detectable amount of CuO was present. Plots of log [CuO]/[Cu2O]1/2) and log ([Cu2O]1/2/[Cu]) (where the brackets designate concentrations in glass solution) vs log pO2 gave best‐fit lines having slopes of ∼ 1/4. From the variation of the equilibrium constant with temperature, the enthalpies of the reactions °Cu2O(glass soln) + 1/4 O2 (g)→ CuO(glass soln) and Cu(glass soln)1/4 O2(g)→ Cu2O(glass soln) in the glasses were estimated to be − 14.57 and − 54.34 kcal/mol, respectively; these values are near the data for isolated Cu‐O systems. The enthalpy for the solution of Cu in glass was estimated to be + 23.7 kcal/mol. On heat treatment, the best ruby was formed in glasses melted at pO2= 10−14 atm; at higher pO2's no ruby was formed, and at pO2≤10−15 the glass produced progressively poorer rubies. Using the thermodynamic data estimated for the system Cu‐O in glass, possibilities for the precipitation of pure solid Cu and Cu2O are discussed. It was shown that Cu2O is primarily responsible for the bright red ruby color in glass.