Toroidal coils

Figure 8.1.5 Schematic of a continuous-flow 13 C probe employing an additional proton toroidal coil...

Tsai, R.S., El Tayar, N., Testa, B. (1991) Toroidal coil centrifugal partition chromatography, a method for measuring partition... 

Zimek Z. (1978) A single-pulse toroidal coil beam-charge monitor. RadiatPhys Chem 11 179-181. 

Inasmuch as the irradiation dose can change from pulse to pulse, it is desirable and often necessary to monitor the dose delivered by each pulse. This can be done by means of various devices a toroidal coil placed around the electron beam [116], a secondary emission chamber placed just before the exit window of the accelerator [13], a charge collector placed in the proximity of the irradiation cell [117], or, electron beam energy permitting, behind the irradiation cell [118], With these devices, a parameter is obtained representing the relative dose of each pulse calibration against chemical dosimeters provides the knowledge of the absolute irradiation dose associated with each individual pulse. 

The effects of the Coriolis force on countercurrent chromatography have been demonstrated on the toroidal coil centrifuge which uses a coiled tube mounted around the periphery of the centrifuge bowl [2]. When a protein mixture containing cytochrome-c. 

Fig. 2 Effects of Coriolis force on partition efficiency and retention of the stationary phase in protein separation by the toroidal coil centrifuge.

Fig. 3 Effects of Coriolis force on the two-phase flow in the separation coil of the toroidal coil centrifuge (a) Coriolis force parallel (b) Coriolis force crossing.

Table 1 Effects of Coriolis Force on Partition Efficiencies of Three Stable Proteins in Toroidal Coil CCC...

Several useful CCC systems have been developed from these centrifuge schemes. The nonplanetary scheme has been used for toroidal coil CCC [3,4], centrifugal precipitation chromatography [5], and on-line apheresis in the blood bank [6,7]. The nonsynchronous scheme has been applied to partition of cells with polymer phase systems and also to cell elutriation with physiological solutions [8,9]. The type J synchronous scheme is further developed into a highly efficient CCC system called high-speed CCC (HSCCC) [10]. 

K. Matsuda, S. Matsuda, and Y. Ito, Toroidal coil counter-current chromatography. Achievement of high resolution by optimizing flow-rate, rotation speed, sample volume and tube length, /. Chromatogr. A 808 95-104 (1998). 

In each separation, the toroidal coil was first entirely filled with a stationary phase (either the upper or the lower phase), and a sample solution was injected into the coil. Next, the mobile phase (organic phase) was pumped into the column while the column was rotated at the desired rate. The effluent from the outlet of the column was collected in test tubes at a rate of 0.2 mL/tube, and at a flow rate of 0.1 mL/min. After the desired peaks eluted, the centrifuge run was terminated and the column contents were fractionated into test tubes at 0.5 mIVtube by eluting the column with the solvent initially used as the stationary phase, at a flow rate of 0.25 mL/min. 

CPC = coil planet centrifuge ACPC = type-I L-angle rotor CPC DCCC = droplet CCC HCPC = horizontal flow-through CPC MLCPC = type-J multilayer CPC SDA = spiral disk assembly TCC = toroidal coil centrifuge ICPC = type-I CPC XCPC = cross-axis CPC. 

The nucleosome core has a disk shape and is composed of eight histone molecules. The octameric core of histones has -145 base pairs of DNA wound about it in approximately PA turns of a left-handed torroidal supercoil. Two copies each of histones H2A, H2B, H3, and H4 are on the inside of the toroidal coil, whereas histone HI is associated with the DNA where it emerges from the core. Each core histone has a basic tail that protrudes from the core structure. In total, -200 bp of DNA is present per nucleosome. 

Toroidal coils, knots and catenanes. Supercoils in DNA need not physically exist as interwound supercoils. The negative supercoils can exist as left-handed toroidal coils, which topologically satisfy the requirement for W. Although in a toroidal coil the helix does not cross itself in the fashion of an interwound supercoil, it does cross itself in the plane of the toroidal coil. The organization of DNA in nucleosomes in eukaryotes involves the toroidal coiling of the DNA around proteins. 

In the toroidal coil CCC (helix CCC) system, operated under a centrifugal force, the dimensions of the coil are reduced (Fig. 2, lower left). The coil is mounted around the periphery of a centrifuge bowl so that the stable, radially acting centrifugal force field retains the stationary phase,... 

Fig. 3 Design of helix CCC (toroidal coil CCC) apparatus. A, Schematic drawing of centrifuge head of original helix CCC apparatus B, cross-sectional view of advanced design of helix CCC equipped with seal-free flow-through device. 1, Motor 2, toothed pulleys 3, toothed belt 4, stationary miter gear 5, horizontal idler miter gear 6, inverted upper miter gear mounted at bottom of column holder shaft (8) 7, gear box 9, column holder 10, coiled separation column 11, hollow tube support 12, flow tubes and 13, clamps.

Several useful CCC systems have been developed from these centrifuge schemes. The non-planetary scheme has been used for toroidal coil centrifugal precipita-... 

Table 1 Effects of Coriolis force on partition efficiencies of three stable proteins in toroidal coil CCC.

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