Gold Ring Research Articles

Gold in Chains: Self‐Assembly of a Gold(I) Catenane

Aurophilic interactions play a pivotal role in the preparation of interlocking “rings of gold”, as described recently [Angew. Chem. Int. Ed. Engl. 1995, 34, 1894]. Secondary Au…Au bonding thus complements the more traditional tools of supramolecular synthesis, such as van der Waals interactions, charge‐transfer interactions, and hydrogen bonding.

A Flight of Swallows

Recent ornithological research on swallow behavior has inspired a fresh look at the well-known flight painted on three walls of room Delta 2 at Akrotiri, Thera. The standard interpretation is that the birds are courting. while an alternative proposal has them feeding fledglings in midair. Instead, the swallows are exhibiting classic signs of aggressive, high-intensity display, the object of which is possession of airborne feathers for use in nests. Similarly represented swallows occur elsewhere in the Theran wall paintings, as well as in other media and contexts. The evidence, especially from gold rings, shows that displaying swallows were important features of Aegean avian epiphany. Seen in this light, Delta 2 assumes new meaning as a cultic space in which iconography and architecture combined to create a dramatic setting for epiphanic ritual.

Development of a rotating ring-disc electrode for high temperature studies in cryolite-based melts

A compact rotating ring-disc electrode incorporating a molybdenum disc, gold ring and boron nitride insulator has been designed, constructed and evaluated in molten cryolite-based electrolytes at temperatures up to 1000°C and rotation rates between 0 and 2000 rpm. The electrode design is extremely versatile and relatively maintenance free, with no visible evidence of melt leakage at the ring-insulator and disc-insulator interfaces. The operating performance of the gold-molybdenum rotating ring-disc electrode was evaluated from collection efficiency measurements based on the dissolution of the disc surface and subsequent detection of soluble species transported to the ring. The observed collection efficiency was less than the theoretical value determined from the geometry of the electrode, primarily because of noncoplanarity of the electrode surface at the working temperature. The results confirm that the electrode should be useful for mechanistic studies in high temperature molten fluoride electrolytes.

Why are large persistent currents observed in small gold rings?

It is demonstrated using three-dimensional computer simulations that some simple non-interacting electron models that include electron scattering by grain boundaries exhibit coexistence of large persistent currents and small conductances, similar to that observed experimentally in isolated micrometre-scale gold rings. Models with simple grain boundaries, and models with small numbers of regularly stepped or atomically rough dilute grain boundaries, have been studied and found to yield similar results, which differ markedly, however, from the predictions of models that assume only random impurity scattering. This difference is due to the fact that equilibrium persistent currents and non-equilibrium transport coefficients are physically different things and depend in different ways on the topology of the defect structure in a conducting ring. Experiments on metal and semiconductor rings that should be able to determine whether this is the explanation of the effects observed by Chandrasekhar et al. (1991) are proposed.

A Novel Approach to Combine Scanning Electrochemical Microscopy and Scanning Photoelectrochemical Microscopy

A new instrumental technique that combines scanning electrochemical microscopy and scanning photoelectrochemical microscopy is described. This technique is capable of monitoring electroassisted and/or photoassisted reactions on semiconductor surfaces either concurrently or sequentially. The instrument uses a probe which consists of an optical fiber coated with gold and isolated from its surrounding environment with a polymer film. Measurements of the electroreduction of at the gold ring which had been generated by photo‐oxidation of Br− on a 50 Å thick film on Ti are discussed.

Syntheses of dinuclear gold(I) ring complexes containing 1,1-dicyanoethene-2,2-dithiolate- S, S and bis(diphosphines) as bridging ligands. X-ray crystal structure of [Au 2μ-(i-MNT)μ-(dppee)

The reaction of [Au 2μ-bis(diphosphine)Cl 2] with potassium 1,1-dicyanoethene-2,2-dithiolate [K 2(i-MNT)], yields the heterobridged complexes: [Au 2μ-(i-MNT)μ-(dppee)] ( 1) (dppee=bis(diphenylphosphinoethylene)), [Au 2μ-(i-MNT)μ-(dppe)] ( 2) (dppe=bis(diphenylphosphino)ethane), [Au 2μ-(i-MNT)μ-(dppb)] 3) (dppb= bis(diphenylphosphino)butane), [Au 2μ-(i-MNT)μ-(dppAs)] ( 4) (dppAs=(diphenylarsino)(diphenylphosphino)- ethane). The molecular structure of 1 is described. Complex 1 crystallized in the triclinic space group P 1 with a=10.451(2), b=11.774(1), c=13.432(2) Å, α=65.40(1), β=82.30(1), γ=77.75(1)° and V=1466.6(4) Å 3. The structure features two linear two-coordinate gold(I) centers bridged by the i-MNT ligand on one side and by a bis(diphosphine) ligand on the other forming a dinuclear complex with an Au···Au distance of 2.867(1) Å in a twisted nine-membered ring structure.

Semiconductor analog of the large persistent currents observed in small gold rings

The remarkably large persistent currents that are observed in disordered micron-scale gold rings at low temperatures have recently been explained in a theory of non-interacting electrons scattered by crystal grain boundaries. The present article examines the possibility that the basic physics underlying this explanation may also have observable consequences in a different system, a ballistic two-dimensional semiconductor ring with a potential barrier. It is predicted, using computer simulations, that such semiconductor rings can exhibit large persistent currents ∼ ev F/L ( L is the ring circumference), despite the electron transmission probability through the barrier being small, in the regime of quantum-mechanical tunneling of electrons through the barrier. This, like the phenomenon observed in gold rings, is a manifestation of the fundamental dissimilarity of non-equilibrium transport phenomena and equilibrium persistent currents. PACS numbers: 73.20. Dx, 73.50.Jt, 72.10.-d

An experimental study of a soft heating method for clinical application of interstitial hyperthermia

A heating device using a small heater made of temperature sensitive ferrite and gold ring was developed for clinical application of interstitial hyperthermia. The temperature characteristics were evaluated and the influence of irradiation with gold was examined. The device had the characteristics of regulating the temperature accurately and automatically. Gold enhanced the effect of irradiation. This method is useful and safe for interstitial hyperthermia of malignant brain tumors and it can be applied clinically. >

Synthesis and characterization of dinuclear gold(I) ring and open-ring complexes containing saturated and unsaturated dithiol bridging ligands and phosphine or bis(diphosphine) donor ligands. Crystal structures of [Au2(.mu.-S(CH2)3S) (.mu.-dppm)], [Au2(.mu.-MNT)(PPh3)2], [Au2(.mu.-S2C6H4) (PPh3)2], and [Au4(.mu.-S2C6H3CH3)2(PEt3)2

Dinuclear gold(I) complexes of the type [Au 2 (μ-dithiolate)(L) n ] where L is a phosphine or bis(dialkylphosphine) have been synthesized. The molecular structures of [Au 2 (μ-S(CH 2 ) 3 S)(μ-dppm)] [dppm=bis((diphenylphosphino)methane)], [Au 2 (μ-MNT)(PPh 3 ) 2 ] (MNT=1,2-dicyanoethene- 1,2-dithiolate-S,S'), and [Au 2 (μ-S 2 C 6 H 4 )-(PPh 3 ) 2 ] are described. In addition, the structure of the tetranuclear bis(dithiolate) [Au 4 (μ-S 2 C 6 H 3 CH 3 ) 2 (PEt 3 ) 2 ] is reported.

The Languages of Losing Battles

Although they serve a common end, written and spoken language complement and compete with each other in Eudora Welty's Losing Battles. Teaching, writing, and books are province of Julia Mortimer, who dies on morning of Granny Vaughn's reunion. Lexie Renfro had presumed to be Julia's successor, she fell down on Virgil and could not finish her training Normal. Gloria Short, Julia's chosen heir, also denies that role when she marries Jack Renfro, her pupil. Julia's opposite, Granny Vaughn, commands a different province, spoken language and its transmission of family history. These feminine modes of expression differ in that written language (books, letters) conceptualizes, moves toward abstractions; whereas oral language deals with concrete, experiential.(1) In a process marked by both modes pulpit oratory of late Grandpa Vaughn diminishes into that of Brother Bethune speaking (to Granny's disparagement) from family reunion pulpit. When Grandpa Vaughn's patriarchal voice is replaced by Brother Bethune's, his Baptist conception of authority (infant baptism can't save souls from sin) is reduced to local mythology, a shift from oracular to anecdotal. Both feminine voice modes thus mark a decline in male authority. Beulah rules her family, not her husband Ralph; and their idolized son Jack's impulsiveness gives rise to demonstrable instances of male folly. Rather than looking inside Curly Stovall's open safe for missing gold ring, for example, Jack carries away whole safe: but he's a man! Done it man's way, Aunt Nanny says.(2) Even account of Grandpa Vaughn's daddy, builder of Damascus Church, implies criticism: he'd preach in church on Sunday and rest of week we could stand on his own front porch and have it to look at (p. 181) - six days, not one, to admire his creation. Whether through Julia's language (meant to lead Banner beyond parochialism) or Granny Vaughn's oral history (to perpetuate family values), male authority is questioned: not out of malice or subversion, rather in an undercurrent of irony, sometimes funny, sometimes, sad. Battles and banners are seminal images in Losing Battles; they mark main conflict of novel between local and absolute. Thus Curly Stovall's store and Gloria's Banner School face each other across road that runs through town as if in course of continuing battle (p. 410). Jack's noisy fight with Curly in store over missing gold ring disrupts Gloria's effort across road to teach her class poem about Columbus and gray Azores. She teaches an ideal of outreach; Jack and Curly's rivalry becomes a comic brawl. Other contenders are two ancient, discolored sawdust poles [left from Dearman's sawmill business] ... like Monitor and Merrimack in history book (p. 410). Aside from its pictures, conceptualizes Civil War issues in abstraction of printed words, whereas actual sawdust piles not only look like ironcla ships, are debilitated physical remnants of Reconstruction itself. The issues of War become localized in concrete images. Written words rather than images signifying combat appear in letter from Julia that Judge Moody reads to reunion (to family's displeasure, who want it told to them); Julia wrote, I've fought a hard war with ignorance. Except in those cases that you can count on your fingers, I lost every battle (p. 298). Moody himself is one success who stayed in Boone County, he never forgave Julia for compelling him to stay there. As a judge he remains her judgment on Banner's ignorance - the very pocket (p. 304). Lexie, Ralph Renfro's old maid sister who wanted to teach school and who dampens spirit of reunion, likewise remarks to Ralph: these children of yours are least prepared to be corrected of any I ever ran up against. How they'll conduct themselves on Day of Judgment I find hard to imagine (p. …

The Archaeological and Literary Evidence for the Burning of the Persepolis Palace

Recent excavations in Macedonia have provided an analogy to the pillaging of the Palace at Persepolis. In plundered tombs at Aiani the excavators found a number of small gold discs with impressed rosettes and of gilded silver ivy leaves; at Katerini some thirty-five gold discs with impressed rosettes, a gold double pin, a gold ring from a sword-hilt, a bit of a gilded pectoral, gilded silver fittings once attached to a leather cuirass, many buttons and other fragments; and at Palatitsia (near Vergina) bits of a gilded bronze wreath and of a gold necklace, and an ivory fitting. It was suggested that some of these objects had been dropped when ornamental facings were being torn away from a wooden funerary couch and from clothing by the robbers, who were probably working at speed and dared not return. In the antechamber of the tomb at Katerini many of the objects I have mentioned were found inside a burnt layer, and M. Andronikos has provided the explanation that they had been burnt on the pyre outside the tomb and then brought inside with the debris of the pyre itself. Nothing else was associated with burnt material.

Electrochemical oxidation of 5‐hydroxytryptamine and 5‐hydroxyindoleacetic acid by integrated pulse linear scan voltammetry at ultrasmall gold ring electrodes

AbstractUltrasmall gold ring electrodes have been constructed by electrodeposition of gold onto carbon ring electrodes. Electrodes thus formed show similar adsorption/desorption peaks for oxygen in H2SO4 solution compared to those obtained at conventional‐sized electrodes. These electrodes have been used in conjunction with linear scan voltammetry and subsequent cleaning pulses to obtain repeatable quantitative results for the electochemical oxidation of 5‐hydroxytrptamine and 5‐hydroxyindoleacetic acid. This technique involves the use of a linearly scanned applied potential, followed by a large positive potential to clean the electrode oxidatively and negative potential for electrode activation. The result of the cleaning pulses is that oxidation products of 5‐hydroxytryptamine are cleaned off the electrode and reproducible voltammograms are obtained.

Electrical-transport properties and microwave device performance of sputtered TlCaBaCuO superconducting thin films

Tl-Ca-Ba-Cu-O high-temperature superconducting thin films were deposited on lanthanum aluminate substrates, by rf magnetron sputtering and postannealing methods. A reproducible fabrication process with low-resistance metal contacts has been established for high-Tc and high-Jc TlCaBaCuO thin films after patterning using standard microelectronic photolithography and wet chemical etching techniques. Low-resistance gold contacts on TlCaBaCuO thin films were obtained by annealing in an oxygen flow of 1 l/min followed by a slow furnace cooling. Specific contact resistivity was approximately 10−10 Ω cm2 below 77 K. High transition temperatures as high as 100 K, and current density at zero magnetic field greater than 105 A/cm2 are routinely obtained in 0.3–0.5 μm TlCaBaCuO thin films. The morphology studies of the films using scanning electron microscopy show the correlation between Jc and the microstructure of the films. Films with featureless morphology have larger zero-field transport currents. The microwave properties of TlCaBaCuO thin films were investigated by designing, fabricating, and characterizing microstrip ring resonators with a fundamental resonance frequency of 12 GHz on 10-mil-thick lanthanum aluminate (LaAlO3) substrates. Ring resonators with a superconducting ground plane of 0.3 μm thickness and a gold ground plane of 1 μm thickness were fabricated and characterized in the temperature range of 60–95 K. Typical unloaded quality factors Q for the ring resonators at 12 GHz were above 1500 at 65 K, compared to an unloaded Q of 370 for a gold ring resonator. A surface resistance as low as 1.5 mΩ at 12 GHz and 77 K was obtained in 0.3 μm TlCaBaCuO thin films using the ring resonator Q measurements. Typical values of penetration depth at 0 K in the TlCaBaCuO thin films were determined to be between 7000 and 8000 Å using the temperature variation of resonance frequency measurements.

A Roman Gold Ring from Kinwarton near Alcester, Warwickshire

A Roman Gold Ring from Kinwarton near Alcester, Warwickshire

Gold contamination of the fine fraction of till during sampling and sample preparation

Contamination of gold ring and natural gold grains into plastic capsules used in INAA analysis and the fine fraction of till (0.064 mm) have been studied. An artificial contamination of till samples with a gold ring caused Au contents of 100–600 ppb in the fine fraction. A few rubbings of plastic capsules with a gold ring gave Au amounts of 15–170 ng per capsule. Natural gold grains of sizes 0.1–1.0 mm added into “gold-free” till samples before drying and sieving caused Au contents of 1–27 ppb into the fine fraction. In a regional geochemical survey an anomaly of a few hundreds of square kilometers with concentrations of 100–600 ppb Au in the fine fraction of till was observed. Later studies showed that this area was very low in Au, concentrations being generally below one ppb. The anomaly was interpreted as a contamination caused by the gold rings of the samplers.

Fabrication of 35 nm linewidth gold rings and observation of h/e and h/2e magnetoconductance oscillations

A detailed description is given of the fabrication of gold rings with a diameter of ∼700 nm and a linewidth between 25 and 50 nm. The fabrication technique is based on electron beam lithography in combination with lift-off.In contrast to previous work, the magnetoconductance of these rings shows at low magnetic field oscillations with flux period h/2e superimposed on oscillations with flux period h/e. At high magnetic fields, only the h/e oscillations are observed.

The Examined Life

6. Stop the favoritism James 2:1-11 1 My brethren, do not hold your faith in our glorious Lord Jesus Christ with an attitude of personal favoritism. 2 For if a man comes into your assembly with a gold ring and dressed in fine clothes, and there also comes in a poor man in dirty clothes, 3 and you pay special attention to the one who is wearing the fine clothes, and say, "You sit here in a good place," and you say to the poor man, "You stand over there, or sit down by my footstool," 4 have you not made distinctions among yourselves, and become judges with evil motives?

Vibrational autodetachment spectroscopy of Au−6 : Image-charge-bound states of a gold ring

Spectral experiments on mass-selected negative cluster ions of gold and silver were performed in the wavelength range near the threshold for one-photon photodetachment of the extra electron. The Au−6 cluster ion displayed a uniquely well resolved spectrum consisting of a progression in a single vibrational mode. Details of this threshold photodetachment spectrum and the associated photoelectron energy distribution suggest an explanation based on autodetachment from totally symmetric vibrational levels of very weakly bound excited electronic state (bound by image charge forces) of the Au−6 cluster in the form of a planar, six-fold symmetric, gold ring.

Electrochemical examination of the copper oxidation state in the fluorine doped Nd 2CuO 4 superconductor

Measurements of the flux of copper species reaching the ring electrode of a rotating Nd 2CuO 4− x F x disk-gold ring electrode configuration in acidified chloride solutions allow for the real-time analysis of x as the superconductor is etched. The method is based on analyzing the ratio of copper oxidation states arising from the open circuit dissolution reaction of the Nd 2CuO 4− x F x disk into chloride solutions. Through voltammetry at the gold ring electrode, the Cu 2+ and Cu 1+ products are measured quantitatively and x determined. For specimens showing a 27 K onset of T c, the average copper oxidation state is 1.74, corresponding to the stoichiometry Nd 2CuO 3.74F 0.26. Superconductor electrode potentials are determined directly by the Cu 2+/Cu 1+ ratios.

Radioactive gold ring dermatitis

A superficial squamous cell carcinoma developed in a woman who wore a radioactive gold ring for more than 30 years. Only part of the ring was radioactive. Radiation dose measurements indicated that the dose to basal skin layer was 2.4 Gy (240 rad) per week. If it is assumed that the woman continually wore her wedding ring for 37 years since purchase, she would have received a maximum dose of approximately 4600 Gy.