Gold black

In contrast to the molecular wire of molecular interface, electron mediators are covalently bound to a redox enzyme in such a manner as an electron tunneling pathway is formed within the enzyme molecule. Therefore, enzyme-bound mediators work as molecular interface between an enzyme and an electrode. Degani et al. proposed the intramolecular electron pathway of ferrocene molecules which were covalently bound to glucose oxidase [ 4 ]. However, few fabrication methods have been developed to form a monolayer of mediator-modified enzymes on the electrode surface. We have succeeded in development of a novel preparation of the electron transfer system of mediator-modified enzyme by self-assembly in a porous gold-black electrode as schematically shown in Fig.12 [14]. 

It is noted that the anodic peak current prominently increases with an increase in the molar ratio of ferrocene to glucose oxidase whilst the amount of enzyme self-assembled on the electrode surface is fixed as presented in Figs. 14-16. This indicates that each modified ferrocene may contribute to electron transfer between the enzyme and the electrode in the case of gold-black electrode, the ferrocene-modified enzyme could form multi electron transfer paths on the porous gold-black electrode. 

Fig. 16 Relationship between the number of bound ferrocenes per glucose oxidase and anodic peak current on the gold black electrode...

Substrate concentration dependence of response current of the gold-black electrode was compared with that of gold disk electrode. The ferrocene-modified glucose oxidase which was used in this measurement had 11 ferrocenes per glucose oxidase. The electrode potential was controlled at 0.4 V vs. Ag/AgCl. The response current was recorded when the output reached at a steady state. The response current was enhanced when ferrocene-modified glucose oxidase was self-assembled on a porous gold-black electrode. 

The porous matrix of gold-black electrode has enabled ferrocene-modified glucose oxidase to perform the smooth electron transfer by means of easy access between self-assembled molecules and electrode surface. 

Aizawa et al. [14] have immobilized mediator-modified glucose oxidase within micropores of a gold black electrode by self-assembling via the thiol-gold interaction. 

Fig.21 Glucose concentration dependence of response current on ferrocene-modified glucose oxidase self-assembledon the gold black ( ) and plain gold (0) electrodes...

O Neill, P., and A. Ignatiev, 1978. Influence of microstructure on the optical properties of particulate materials gold black, Phys. Rev., B18, 6540-6548. 

Imamura M, Haruyama T, Kobatake E, Ikariyama Y, Aizawa M. Self-assembly of mediator-modified enzyme in porous gold-black electrode for biosensing. Sensors and Actuators B 1995, 24, 113-116. 

In Nigeria wealth was displayed in quantities of ivory jewellery in the form of simple bracelets and anklets, and ornaments for the home. In other African countries ivory was used for much less ostentatious items, such as hairpins or ear studs. With the arrival of the Europeans a market opened up for exporting carved objects, but most of the material was exported in its raw state. In the time of slavery it became part of the white gold/black gold story. Local men were commandeered to carry the tusks to the coast and onto the ships, after which the men themselves were ordered to stay on board and were taken away to be traded as slaves. 

Fig. 7.13.21 shows a cross section of a thermoelectric infrared sensor. This structure has potentially low cost because of its high compatibility with the widely used SiCMOS ICs [4], To improve sensitivity, the sensor uses a swastika pattern with a curved beam and a gold-black absorber with good IR absorptivity so as to attain a UV absorption coefficient of 90% or larger. 

Figure 4.1 Voltammetric detection of DNA oligonucleotides. After immobilization of the ssDNA probe on gold (black), the electrode surface was additionally covered with mercaptobutanol (gray) to prevent unspecific binding. Competitive hybridization of MB-labeled reporter and nonlabeled target ssDNA. The amount of hybridized reporter DNA is gauged by differential pulse voltammetry. [From Panke (2007).]...

The principle of the Thomson polymer IR sensor is represented by Fig. 14 and Fig. 15. The P(VF2 TrFE) copolymer constitues the pyroelectric layer (5-10 pm), the insulation layer is a polyimide (10 pm). The upper electrode is also the infrared absorber and is made in aluminium or gold black. The lower level is the CCD level which constitues the second electrode. The polarisation of the polymer is realized by application of 100 V/pm between the two electrodes of the pyroelectric capacitor. 

Fig. 27 From top to bottom (and left to right) bubble generation from 1 to 4 pit arrangements at low and high power. Left Bright field illumination (inverted colour) showing bubble patterns at slow speed imaging. Right Shapes of cleaned areas in gold (black) caused by bubble cavitation. Reproduced with permission from [110], Copyright 2012 AIP Publishing...

On the other hand, it is easy to prepare metals in the form of evaporated thin films on a large variety of substrates. Their geometries are readily dictated by the evaporation masks employed. By making the evaporated films very thin, heat capacities can be made to be very low, and the speed of response can be high. Because of the high reflectivity of metals it is necessary to overcoat the films with an evaporated film of a material such as platinum or gold black which will absorb the incident radiation. Like thermistor bolometers, most metal film bolometers operate at room temperature. See Dewaard and Wormser [2.79] for additional details. 

In practice, few surfaces closely approach blackbody behavior, e.g., carbon black, platinum black, gold black, and carborundum. However, a small... 

An alternate approach involves the use of spatially uniform detectors. Blevin and Brown (26) developed a gold-film bolometer with a broadband response that was uniform to within 2% over an area of 9 x 4 mm for a 0.25-mm beam spot. The detector used a NaCl window and had a minimum detectable power of 4 nW for a bandwidth of 1 Hz. Hanssen and Snail (49) measured the spatial uniformity of a windowless, 14 x 14-mm gold-black coated pyroelectric (LiTaOj) detector at 10.6 /im. For a 0.25-mm beam spot, the response was uniform to within +1.7% over 13 mm, excluding one narrow scratched region where a 10-15% deviation was observed. The minimum detectable power was 1 /iW (standard uncertainty) for a bandwidth of 1 Hz (50). 

Fig. 4. Response of a gold-black coated pyroelectric (LiTaOj) detector at 10.6 fan versus incidence angle for unpolarized radiation.

In the IR range the absorption coefficients of various polymer materials have, in general, not flat but rather compUcated shapes and are small, so that thin polymer film almost cannot absorb the incident rarUatioo. Then on IR-absorbing layer such as gold black, which can absorb the radiatioo almost perfectly throughout the whole IR range. 

Fig. 12.8 Tg as a function of the nominal interfacial energy for the following confined pol5nners 22 nm thick PS supported on OTS (orange diamonds), 20 nm thick PS capped in A1 (pink triangles), 22 nm PVAc supported on silicon oxide (green open diamonds), 22 nm PVAc supported on A1 (red open squares), 22 nm PVAc supported on gold (black open circles) 13 nm PET capped in A1 (blue squares) 10 nm polysulfone (PSF) capped in A1 (blue pentagon) 22 nm PC capped in A1 (dark cyan stars). The arrows indicate the shift of Tg occurring after prolonged annealing in the melt state (reprinted with permission from ref. [115])...

Gold black Ultrafine particles of gold, often made by gas evaporation. Used as an IR radiation adsorber in bolometers. 

Polarizing the metal in acid above ca. 1.80 V results in the formation of a reddish brown oxide layer which on reduction yields a relatively active form of the finely divided metal, i.e., a type of gold black. The reactions involved were investigated using potential sweep techniques by Lohrengel and Schulze, who found that rapid growth in add required a potential in excess of 2.0 V a multilayer film was clearly formed under such conditions as two, and occasionally three, peaks were recorded on the cathodic sweep. These authors postulated that while the inner layer was both a poor electronic and ionic conductor, the reverse conditions prevailed for the thicker outer film, which they also suggested was rather compact in character. 

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