Yellow Gold Research Articles

Anelastic Effects of Phase Decomposition in 14-Carat AuAgCu Alloy

A relaxation peak has been observed in the internal friction spectrum of 18-carat AuAgCu yellow gold alloys at about 750K for 0.5Hz. It is related to the presence of grain boundaries, since it is absent in the spectrum of single crystals. For the 14-carat yellow gold alloy (Au38%Ag32%Cu30%), a phase decomposition between silver-rich and copper-rich solid solution occurs in the same temperature range. The effects of the phase decomposition on the internal friction and the dynamic modulus are studied by isochronal and isothermal measurements and correlated with the microstructure evolution. Upon cooling, the phase decomposition starts at grain boundaries at about 840K, producing a fine lamellar structure, and the grain boundary peak amplitude strongly decreases. As the phase decomposition progresses at the interior of the grains upon further cooling, the internal friction background increases. It remains very high in heating until solid solution homogenisation, which occurs above 890K. Such an increase of the internal friction background is observed also in the single crystalline alloy and may be attributed to the interfaces between lamellae of the silver and copper-rich phase.

Functional Property of Honey from <i>Echium vulgare</i>

Chemical property of honey from Echium vulgare was investigated. In comparison with other honey species, the con-tents of total phenolic compounds and total flavonoids were the highest. α-Amylase activity was also extremely high: about three to nine hundred times as much as those of other honey species. The antioxidative activity of honey was investigated using four different methods. Honey from E. vulgare showed the best performance in inhibiting lipid peroxidation and scavenging superoxide anion radicals, hydroxyl radicals, and DPPH radicals. Moreover, it exhibited stronger inhibition activity of ACE. It is known that higher antioxidative activity and scavenging activity against active oxygen species in honey species related to their colour. In the present study, however, it suggests that the phenolics in honey from E. vulgare with yellow gold colour might be the major active component responsible for the strong antioxidative activity and radical scavenging activity.

The cultural logic of racism in Richard Wright’s Native Son

The decolorization and mineralization of an azo dye, brilliant golden yellow (BGY, i¬max416 nm, i¥ = 7.81 x 103 Lmol-1 cm-1) by Fenton and photo-Fenton processes were investigated. The rate of decolorization is strongly dependent on the pH, initial concentrations of the dye, Fe(II) and H2O2. The effect of these parameters has been studied and the optimum operational conditions of these two methods were found. The optimum conditions were obtained at pH=3 for both processes. The photo-Fenton method proved to be the most efficient and occurs at a much higher oxidation rate than Fenton process. The results showed that about 99% of the dye decolorized within 20 and 5 min for Fenton and photo-Fenton processes, respectively. Characterization of the products after mineralization is discussed. Keywords: Dye pollution, Fenton and photo-Fenton processes, brilliant golden yellow, decolorization, mineralization.

Grain boundary relaxation and grain growth in 18-carat yellow gold alloy

A high-temperature anelastic relaxation peak in the mechanical loss spectrum of 18-carat yellow gold polycrystals is analysed and interpreted as due to grain boundary sliding accommodated predominantly by elastic deformation of the grains. The characteristic time scale of the relaxation process tvaries with the grain size d, and the grain size exponent is found to be m = 1.09 +/- 0.10 which is in perfect accord with the Zener model that attributes a grain boundary relaxation to viscous sliding along the grain boundaries. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Monitoring Rhodosporidium toruloides NCYC 921 batch fermentations growing under carbon and nitrogen limitation by flow cytometry

The yeast Rhodosporidium toruloides NCYC 921 was grown on carbon or nitrogen limited batch cultures. The fermentations were monitored using traditional techniques and multi-parameter flow cytometry. The lipid content was assessed by flow cytometry in association with the fluorocrome Nile Red which emits yellow gold fluorescence when dissolved in neutral lipids and red fluorescence when dissolved in polar lipids. In this way, it was possible to at-line monitor the yeast lipid composition in terms of polarity classes throughout the batch growths. It was found that the neutral lipids decreased during the carbon-limited stationary phase, and increased during the nitrogen-limited batch growth. The maximum lipid content was obtained for the nitrogen-limited yeast culture (24% w/w lipids). The yeast cells with permeabilised membranes profile remained almost unchanged during the time course of both fermentations. The scatter light measurements (forward and side scatter signals) provided information on the yeast growth phase. The multi-parameter flow cytometric approach here reported represents a better control system based on measurements made at the single cell level for optimization of the yeast lipid production bioprocess performance.

HUGHESITE, Na3Al(V10O28)*22H2O, A NEW MEMBER OF THE PASCOITE FAMILY OF MINERALS FROM THE SUNDAY MINE, SAN MIGUEL COUNTY, COLORADO

We report on the discovery, description and solution of the structure of a new member of the pascoite family of minerals, hughesite, from the Sunday mine, Gypsum Valley, San Miguel County, Slick Rock District, Colorado, USA (38°4’19” N, 108°48’15” W). Orange to golden orange crystals of hughesite occur in efflorescent crusts, averaging 2 mm thick, on the sandstone walls of mine workings and in rock fractures. Hughesite forms through the oxidation of corvusite, (Na,Ca,K) 1– x (V 5+ ,V 4+ ,Fe 2+ ) 8 O 28 •4H 2 O, and montrosite, (V 3+ ,Fe 2+ ,V 4+ )O(OH), the primary vanadium oxide phases present, as they react with acidic, oxidizing groundwater. Crystals vary in habit, including blocky, spear-shaped, and platy, with one good cleavage on (001). Crystals are transparent to translucent with a subadamantine luster, and upon partial dehydration, they become opaque. Hughesite is biaxial (–), with α 1.698(5), β 1.740(5), γ 1.770(5), and the measured 2 V 589nm is 84(2)°. It exhibits a strong r > v dispersion, and is pleochroic with X = Y light golden yellow, and Z dark golden yellow. Its absorption is characterized by Z > Y = X . Electron-probe microanalysis and the crystal-structure solution provided the empirical formula Na 2.99 Al 1.05 (V 10 O 28 )•22 H 2 O (based upon V = 10 apfu ). The ideal formula of hughesite is Na 3 AlV 10 O 28 •22H 2 O. The density calculated from the empirical formula using the single-crystal cell data is 2.29 g/cm 3 . Hughesite is triclinic, space group P 1, with a 8.668(4), b 10.295(4), c 12.908(5), α 105.826(9), β 97.899(9), γ 103.385(9)°, V 1053.0(8) A 3 , and Z = 1. The strongest four lines in the powder-diffraction pattern [ d in A(I) hkl ]: are 12.24(100)001, 8.25(38)100, 9.50(30)010, and 8.99(28)011. The crystal structure, refined to R 1 = 0.0496, consists of two components, the structural unit, which contains the decavanadate (V 10 O 28 ) 6− polyanion, and the fully hydrated interstitial complex, composed of two separate components, a Na 3 (OH 2 ) 12 O 2 trimer with two distinct cation sites, and a Al(OH 2 ) 6 monomer.

A new highland species of Pristimantis Jiménez de la Espada, 1871 (Anura: Strabomantidae) from the Pantepui region, northern South America

A new strabomantid frog of the genus Pristimantis Jiménez de la Espada, 1871 is described from the Eastern Pantepui Region, Guiana Shield, northern South America. The new species, Pristimantis aureoventris sp. nov., is known so far from two neighbouring tepuis, namely Wei Assipu Tepui (type locality) at the border between Guyana and Brazil and Mount Roraima in Guyana, and occurs between 2210–2305 m elevation. The new taxon is distinguished from all known congeners by the following combination of characters: Finger I < II; tympanum distinct; basal webbing between Toes IV-V; broad lateral fringes on fingers and toes; ventral skin areolate; vocal slits absent in male; two non-spinous whitish nuptial pads and vocal sac present in male; high degree of pattern polymorphism; throat, chest, and belly golden yellow, usually with reddish brown to dark brown mottling; internal organs little or not visible through the ventral skin in life. The call of the new species consists of bouts of a single amplitude-modulated (decreasing to the end) note repeated at a rate of ca. 18 notes/min with a dominant frequency ranging from 2180 to 2430 Hz.

Extractive removal of astacryl blue BG and astacryl golden yellow dyes from aqueous solutions by liquid–liquid extraction

Extractive removal of cationic dyes namely astacryl blue BG and astacryl golden yellow were carried out from aqueous solutions using salicylic acid dissolved in toluene. Extraction efficiency was studied under various experimental conditions, such as pH of feed solution, concentration of stripping agent, extractant concentration, extraction time, temperature, initial dye concentration, and reusability of solvent. Under the optimised experimental conditions 93–98% of dyes were extracted. The extracted dyes were quantitatively stripped with sulphuric acid solution. The organic phase obtained after the stripping of dyes was washed with dilute sodium hydroxide solution to neutralise any sulphuric acid trapped or adhered to the solvent and then with distilled water. This solvent was reused in succeeding extraction of dyes. The optimised conditions were: pH of the feed 10 ± 0.2, extractant concentration 2.89 × 10 − 2 mol/L, concentration of stripping agent 1.5 N H 2SO 4, extraction time 4 min, initial dye concentration 50 mg L − 1 , aqueous to organic (A/O) ratio 1:1. Finally real industrial textile wastewater was tested under optimised conditions, 92% of dye was extracted at 25 °C.

The osteogenic differentiation of human osteoprogenitor cells on Anodic-Plasma-Chemical treated Ti6Al7Nb

Biological integration of an implant to surrounding bone is an important event for its clinical success and is driven by numerous factors, including the attraction of bone forming cells. The implant’s surface properties influence the initial cell response at the cell/material interface, ultimately affecting the rate and quality of new tissue formation and the stability of the implant. As a consequence, various surface treatments have been developed to increase the clinical performance of titanium-based implants. Among them, the Anodic Plasma-Chemical (APC) technique allows for the combined chemical and morphological modification of titanium surfaces in a single process step. In the present study, we compared the potential of APC surface treatment of high-strength titanium alloys with vacuum plasma spray treatment and yellow gold anodization in supporting osteogenic differentiation of two different osteoprogenitor cell types. Both human fetal osteoblast cell line (hFOB1.19) and human mesenchymal stromal cells showed extensive cell spreading, faster cell growth and differentiation on APC surfaces compared to vacuum plasma spray treated and yellow gold anodized surfaces. Our findings showed that APC titanium-based surfaces provided an effective substrate for osteoprogenitor cells adhesion, proliferation and differentiation.

QUALITY OF YELLOW AND CHARENTAIS MELONS AFFECTED BY THE FRUIT SIZE

In this study the objective was to evaluate the quality of Yellow hybrid Gold Mine (Group Inodorus) and Charentais hybrid Fleuron (Group Cantaloupensis) influenced by the fruit size. The experiment was conduced between 11/24/2003 and 03/11/2004 at the Federal University of Vicosa. The fruits were harvested 42 days after anthesis at commercial stage and graded as type 6 (1.63 kg), 9 (1.05 kg) and 12 (0.74 kg) fruits/box with capacity of 10 kg of Gold Mine and type 4 (1.37 kg), 6 (0.90 kg) and 8 (0.64 kg) fruits/box with capacity of 5 kg of Fleuron fruits. For the hybrid Gold Mine the pulp firmness, pericarp thickness and respiration were higher in the fruits type 6. However, the total soluble solids were reduced and the ethylene production increased in smaller fruits. In the hybrid Fleuron the pulp pH, firmness, titrable acidity, total soluble solids and ethylene production were higher in fruits graded as type 4, but the pericarp thickness diminished with the reduction of the fruit size. The results of this experiment suggest that fruits with smaller fresh weight are qualitatively inferior regardless the hybrid.

열처리에 의한 14K, 18K yellow gold alloy의 경도 향상 및 표면 결함 완화

In this study, we conducted heat treatment on 14K, 18K yellow gold alloy at various temperature conditions for improving their hardness and moderating their surface defects. Also after the heat treatment we used EPMA (Electron Probe Micro Analyzer), XRF (x-ray Fluorescence spectroscopy) for qualitative analysis and OM (optical microscope), SEM (scanning electron microscope) to investigate the changes of surface grain boundary. We used Vickers hardness tester to verify the changes of hardness. After the heat treatment, 14K, 18K gold alloys showed improved hardness and moderated surface defects at specific temperatures and duration.

Auriacusite, Fe3+Cu2+AsO4O, the first M 3+ member of the olivenite group, from the Black Pine mine, Montana, USA

Auriacusite, ideally Fe3+Cu2+AsO4O, is a new arsenate mineral (IMA2009–037) and the Fe3+ analogue of olivenite, from the Black Pine mine, 14.5 km NW of Philipsburg, Granite Co., Montana, USA. It occurs lining quartz vughs and coating quartz crystals and is associated with segnitite, brochantite, malachite, tetrahedrite and pyrite. Auriacusite forms fibrous crystals up to about 5 µm in width and up to about 100 µm in length, which are intergrown to form fibrous mats. Individual crystals are a brownish golden yellow, whilst the fibrous mats are ochreous yellow. The crystals have a silky lustre and a brownish yellow streak. Mohs hardness is about 3 (estimated). The fracture is irregular and the tenacity is brittle. Auriacusite crystals are biaxial (+), with α = 1.830(5), β = 1.865(5) and γ = 1.910(5), measured using white light, and with 2V meas. = 83(3)o and 2V calc. = 84.6o. Orientation: X = a, Y = c, Z = b. Crystals are nonpleochroic or too weakly so to be observed. The empirical formula (based on 5 O atoms) is (Fe 1.33 3+ Cu0.85Zn0.03)Σ2.21(As0.51Sb0.27Si0.04 S0.02Te0.01)Σ0.85O5. Auriacusite is orthorhombic, space group Pnnm, a = 8.6235(7), b = 8.2757(7), c = 5.9501(5) A, V = 424.63(6) A3, Z = 4. The five strongest lines in the powder X-ray diffraction pattern are [d obs in A / (I) / hkl]: 4.884 / (100) / 101, 001; 2.991 / (92) / 220; 2.476 / (85) / 311; 2.416 / (83) / 022; 2.669 / (74) / 221. The crystal structure was solved from single-crystal X-ray diffraction data utilising synchrotron radiation and refined to R 1 = 0.1010 on the basis of 951 unique reflections with F o > 4σF. Auriacusite is identified as a member of the olivenite group with Fe3+ replacing Zn2+ or Cu2+ in trigonal bipyramidal coordination. Evidence suggests that auriacusite is an intermediate member between olivenite and an as yet undescribed Fe3+Fe3+-dominant member. The name is derived from the Latin auri (golden yellow) and acus (needle), in reference to its colour and crystal morphology.

H2O2-assisted photolysis of reactive dye BES golden yellow simulated wastewater

Reactive dye BES golden yellow simulated wastewater was treated with H(2)O(2)-assisted photolysis method. Influences of factors such as reaction time, initial pH and H(2)O(2) dosage were investigated, and the reaction kinetics of the process were explored. Results showed that, the degradation of 200 mg/L BES golden yellow solution happened only in the presence of both conditions: UV irradiation and H(2)O(2) addition. Initial pH and H(2)O(2) dosage had remarkable influence on the removal efficiency of the dye. Through several groups of univariate experiments, the optimum pH and H(2)O(2) dosage of the photolysis process were found to be 6-7 and 0.0375 mL 30% H(2)O(2) per milligram of BES golden yellow, respectively. The photolysis process was approximately in accordance with the second-order kinetic equation.

Stress-induced and atomic ordering in 18-carat Au–Cu–Ag alloys

Atomic ordering and stress-induced ordering (Zener relaxation) were studied in a series of 18-carat (75 wt%) yellow gold alloys (Au–Cu–Ag) by means of isothermal mechanical spectroscopy with a forced torsion pendulum at low frequencies. In the high-temperature solid solution, the Zener peak increases critically according to a Curie–Weiss type law when approaching the transition temperature to the ordered phase from above, then breaks down and disappears as the alloy orders. The two critical temperatures as well as the activation energy for the Zener relaxation are reported for each alloy of the series. The composition dependence of the two ordering phenomena is discussed, including the aspect of phase separation into a copper-rich and silver-rich phase as predicted by the ternary phase diagram.

Corrosion behaviour of a dental alloy in some beverages and drinks

The aim of the present work was to perform a systematic study of the effect of several beverages (alcoholic drinks, natural and artificial fruit juices, vinegar, soft drinks, milk) on the corrosion behaviour of an aluminum–bronze dental alloy. Results were compared to those obtained in artificial saliva and in a solution of sodium chloride. The material used was an aluminum–bronze alloy frequently used in Latin-American countries because of its similarity in appearance to the yellow gold alloys and of economic reasons. The investigation was carried out by means of traditional electrochemical techniques: polarization tests, polarization resistance measurements and weight loss tests. The ranking of aggressiveness of the beverages and solutions studied is given by the corrosion rate computed from the weight loss measurements, and it is as follows: artificial saliva, lemon juice, vinegar, 1 M NaCl, white wine, red wine and artificial orange juice. The aggressiveness of the different liquids is independent of both the pH and electrical conductivity of the solution. The most aggressive beverage (artificial orange juice) generates a corrosion rate only 1 order of magnitude higher than that of saliva, a difference that is not relevant for the odontological use considering the short time that beverages are in contact with dental alloys in the oral environment.

Volatile Aroma Composition of Chrysanthemum indicum L. Flower Oil

The aroma constituents of Chrysanthemum indicum L. were separated by the hydro distillation extraction method using a Clevenger-type apparatus, and were analyzed by gas chromatography-mass spectrometry (GC/MS). The yield of Chrysanthemum indicum L. flower oil was 2.0% (w/w) and the color was light golden yellow. Sixty-three volatile flavor components, which make up 89.28% of the total aroma composition of the flower oil, were tentatively characterized. This essential oil contained 35 hydrocarbons (48.75%), 12 alcohols (19.92%), 6 ketones (15.31%), 3 esters (4.61%), 5 aldehydes (0.43%), 1 oxide (0.22%), and 1 miscellaneous component (0.04%). α-Pinene (14.63%), 1,8-cineol (10.71%) and chrysanthenone (10.01%) were the predominant volatile components in Chrysanthemum indicum L., an aromatic medicinal herbaceous plant.

Conversation with Chen Kuan Lee about roof profiles (1947)

We spoke about the usability and further development of the Chinese roof profile in Chinese buildings today. How did this roof, this remarkable Chinese roof, which gives Chinese architecture a special signature against which other features pale into insignificance, come about? It is a saddle roof with an exaggerated rounding of the ridge and wide out-swinging eaves, and the surface is raised to the highest shine through the intensity of gleaming glazed tiles which display all the colours of nature: light and dark red, lemon yellow and golden yellow, sky blue and peacock blue, rare green and brown glazes of every kind. Through the wave profile of the over- and under-lapping tiles – which all adds to the formal effect – it survives every kind of weather.

On the strengthening mechanisms of 18 carat yellow gold and its mechanical behaviour

In order to contribute to a better understanding of the mechanical properties of gold alloys this paper investigates the mechanical behaviour of an 18 carat yellow alloy; the strain hardening behaviour during a tensile test was measured in the annealed as well as in different cold-work conditions. In addition, the contribution of different strengthening mechanisms is discussed on the basis of current results and of data reported in literature. In particular, the contributions of grain size refinement and copper solid solution alloying in improving the mechanical strength of gold alloys were quantified.

Attraction of Astylus variegatus (Germ.) (Coleoptera: Melyridae) by volatile floral attractants

The beetle Astylus variegatus (Germ.) (Coleoptera: Melyridae) is frequently found in flowers feeding on pollen. Responses of A. variegatus to volatile floral attractants were studied in common beans (Phaseolus vulgaris L.) fields. Traps originally designed to capture Diabrotica speciosa (Germ.) (Coleoptera: Chrysomelidae), consisted of plastic bottles (2 L) with 150 holes (5-mm diameter) yellow gold painted and containing inside a plastic strip (3.5 <FONT FACE=Symbol>´</FONT> 25 cm) with Lagenaria vulgaris (L.) powder (0.28% B cucurbitacin - feeding stimulant and arrestant for diabroticites) sprayed with carbaril insecticide. Treatments consisted of 1,4-dimethoxybenzene (one or two dispensers per trap), 1,4-dimethoxybenze + indole, 1,4-dimethoxybenzene + cinnameldehyde and control. Volatile average release rates (over ten days) was approximately 32 mg day-1 per dispenser under laboratory conditions. 1,4-dimethoxybenzene-lured traps caught significantly more beetles than the control, three and seven days after trap setting. Ten days after the onset of the experiment, there were no differences in number of beetles caught by treatments. Captures were higher in the 1,4-dimethoxybenzene + cinnamaldehyde treatment than in 1,4-dimethoxybenzene only in the first assessment. Adding indole to 1,4-dimethoxybenzene did not improve beetle captures.

A new variety and a new forma of Chimonanthus Lindl. from Shennongjia,China

描述了蜡梅(Chimonanthus praecox L.)一新变种即卷瓣蜡梅,该变种与原变种的主要区别是中花被片高度反卷,中被片颜色为白色或金黄色,主要分布于神农架林区.其中中被片颜色为白色的卷瓣蜡梅可以被看作一个新变型跳枝蜡梅.