Of tumbling

Monson P R and McClain W M 1970 Polarization dependence of the two-photon absorption of tumbling molecules with application to liquid 1-chloronaphthalene and benzene J. Chem. Rhys. 53 29-37... 

Diamonds were first discovered in ancient times in India and Borneo and later in Brazil in 1670 in alluvial deposits where water had sorted minerals on the basis of density and toughness. This type of tumbling often concentrates the better quality crystals such as those found in the ocean off the west coast of Africa. Exploration can be done by stream panning or drilling in conjunction with a search for the heavy mineral assemblages that accompany diamond. Alluvial deposits account for about 40% of the diamond found in primary sources. 

L Inside length of tumbling mill m ft X, Size of coarser feed to mill cm in... 

Particle Motion and Scale-Up Veiy little fundamental information is published on centrifugal granulators. Qualitatively, good operation rehes on maintaining a smoothly rotating stable rope of tumbling... 

Principles The process consists of tumbling the metal to be coated with a powder of the coating metal. It is considered that a form of welding is involved, but the type of conditions conducive to successful deposition indicates that the deposit adheres by mechanical keying (A/, must therefore be relatively soft) and adhesive forces. Thus pretreatments such as abrading or pickling enhance the keying effect, and the use of a soft metal... 

In addition to the dipole-dipole relaxation processes, which depend on the strength and frequency of the fluctuating magnetic fields around the nuclei, there are other factors that affect nOe (a) the intrinsic nature of the nuclei I and S, (b) the internuclear distance (r,s) between them, and (c) the rate of tumbling of the relevant segment of the molecule in which the nuclei 1 and S are present (i.e., the effective molecular correlation time, Tf). 

In order to combat this, the rotating frame Overhauser effect spectroscopy (ROESY) techniques can be employed. An in-depth discussion of how this technique works is outside the remit of this book but suffice to say, in the ROESY methods (1- and 2-D), NOE data is acquired as if in a weak r.f. field rather than in a large, static magnetic field and this assures that all NOEs are present and positive, irrespective of tumbling rate and magnet size. It is possible that some TOCSY correlations can break through in ROESY spectra but these will have opposite phase to the genuine ROESY correlations and so should therefore not be a problem - unless they should overlap accidentally with them. A 2-D ROESY spectrum of the naphthalene compound is shown below (Spectrum 8.6). 

Carbon black adsorbed OLOA 1200 very strongly, eventually picking up 5% of its weight in dispersant. The first 2% adsorbed almost instantly, but additional increments adsorbed more and more slowly (see Figure 5). Such time-dependence in adsorption of large molecules is quite common (15), but is seldom studied. The adsorption isotherms determined after 48 hours of tumbling at 25°... 

Figure 8. Effect of tumbling time on screen loading density...

Then each sample was subjected to. a predetermined number of tumblings (same for each sample) and new charge immediately measured. It was found that in each case the charges were greater than before turfibling. Results of tests are given in Table E8 6) H. Rathsburg ... 

Mariner 9 tly-by of Mars revealed a surface remain of massive blocks of tumbled character cut by ridges and grahen-type troughs Huge volcanic peaks dominate a pock-marked landscape. Extensive channels characierislrc of concentrated erosive powers of torrential floods were also evident, as were braided stream systems emanating front what were resolved to be plateau-type elevations. 

---