Double shell technique

Double Shell Technique. Plates were constructed of a hammered undecorated exterior plate and a hammered interior plate with a repousse decoration. The two were secured together either by soldering or by bending the edges of the exterior plate inward and hammering them down over the interior plate. 

Radiographic studies on more than 100 Sasanian silver artifacts and an equal number of related silver objects strongly indicate that the Sasanian silversmith used hammering exclusively as the major shaping technique for all his objects. Among vessels accepted as genuine Sasanian, none were found that appeared to have been made by the double shell technique or that could be positively identified as cast. 

The incorrect description by Orbeli and Trever of Sasanian silver-smithing techniques did not misinform the serious scholar alone the modem forger was fooled also. Many Sasanian silver objects exist that were manufactured either by the double shell technique or by casting. Since our study indicated that these techniques were not used by the Sasanian silversmith, the authenticity of such objects should be considered very questionable. (Combined anomalies in style, iconography, elemental analysis, method of manufacture, and corrosion should provide, of course, the definitive evidence that these objects are not made by a Sasanian silversmith.)... 

Figure 9. (top) Forgery of Sasanian silver gilt plate, private collection. Figure 10. (Tjottomj X-ray radiograph of forgery shown in Figure 9. Decorations appear as darker areas indicating hollow area between two surfaces. This plate is manufactured by the double shell technique, a method not used by Sasanian silversmiths. Exposure 200 kV, 5 mA, lead screens.

A radical is defined to be a molecule in an open shell electronic state. It is often, although not necessarily, very reactive and short-lived in a laboratory environment. Several new species have been studied since the publication of the previous supplement, although the number for which microwave transition frequencies have been measured is still quite small. Many of the new observations have been made by radio astronomers who now have access to frequencies up to 350 GHz. Experiments employing double resonance techniques (simultaneous irradiation with microwaves and either infrared or visible radiation) have also made a contribution to the development of the field. The information about linear molecules, in 2, 2, and states, is contained in section 3.2.1. The non-linear radicals, almost all of which are triatomic, are presented in 3.2.2 (Non-Unear triatomic) and 3.2.3 (Non-linear larger molecules). 

In the same year, our group in Lausanne published first results from a similar instrument which was equipped with an electrospray ion source for producing closed-shell biomolecular ions, the first demonstrations of which were the measurement of the UV spectra of cold, protmiated aromatic amino acids, tryptophan [46], tyrosine [46, 122], and phenylalanine [122]. Spectroscopic detection is achieved by measuring the small percentage of parent ions that fragment subsequent to UV absorption. The internal temperature of the ions was estimated to be 11-16 K from an analysis of the intensity of hot band transitions of low frequency vibrational modes. If the temperatures achieved in buffer-gas cooled ion traps are low enough and the spectra sufficiently simple, one can often resolve UV absorption spectra for different stable cOTiformers of the molecule [122]. In this case, one can use the IR-UV double resonance techniques so profitably employed in supersonic molecular beam studies [91,123-128] to measure conformer-specific infrared spectra, and this was applied by Steams et al. to both individual amino acids [129] as well as peptides with up to 12 amino acid residues [130]. Subsequent improvements to the Lausanne machine (Fig. 7) included the addition of an ion funnel to... 

Solid—solid blending can be accomplished by a number of techniques. Some of the most common include mechanical agitation which includes devices such as ribbon blenders, impellers, paddle mixers, orbiting screws, etc a rotary fixed container which includes twin-shell (Vee) and double-cone blenders and fluidization, in which air is used to blend some fine powders. 

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