Spherical Chains Research Articles

Dynamical properties of colloidal systems: II. Correlation- and response functions

For systems of interacting Brownian particles a Fokker-Planck equation is derived for the probability distribution function of the concentration fluctuations, using assumption of a Gaussian static distribution function. The drift- and the diffusion term are determined by static correlation functions. By this approach specific properties of different systems as e.g., suspensions of charged spherical particles or chain polymers are taken into account. Although the diffusion term is fluctuation dependent the properties of detailed balance and both fluctuation dissipation theorems are satisfied. Using the formalism of Martin, Siggia and Rose, Dyson- and vertex-equations for the two-particle correlation functions are derived. An explicit calculation of these functions, together with related quantities as the dynamic structure factor, and of the diffusion coefficients, is given in a mean-field approximation. The results are compared with several earlier theories, which were developed for specific systems.

Accurate calculation of hydrodynamic interactions in polymer solutions and suspensions

A solution was obtained of the Navier-Stokes equation of axisymmetrical slow motion of spherical chains. Correlation ratios were derived between the coefficient of forward friction and the number of spheres and the distance between them.

Purification and properties of Renilla reniformis luciferase.

Luciferase from the anthozoan coelenterate Renilla reniformis (Renilla luciferin:oxygen 2-oxidoreductase (decarboxylating), EC 1.13.12.5.) catalyzes the bioluminescent oxidation of Renilla luciferin producing light (lambdaB 480 nm, QB 5.5%), oxyluciferin, and CO2 (Hori, K., Wampler, J.E., Matthews, J.C., and Cormier, M.J. (1973), Biochemistry 12, 4463). Using a combination of ion-exchange, molecular-sieve, sulfhydryl-exchange, and affinity chromatography, luciferase has been purified, approximately 12 000-fold with 24% recovery, to homogeneity as judged by analysis with disc and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, gel filtration, and ultracentrifugation. Renilla luciferase is active as a nearly spherical single polypeptide chain monomer of 3.5 X 10(4) daltons having a specific activity of 1.8 X 10(15) hp s-1 mg-1 and a turnover number of 111 mumol min-1 mumol-1 of enzyme. This enzyme has a high content of aromatic and hydrophobic amino acids such that it has an epsilon280nm 0.1% of 2.1 and an average hydrophobicity of 1200 cal residue-1. The high average hydrophobicity of luciferase, which places it among the more hydrophobic proteins reported, is believed to account, at least in part, for its tendency to self-associate forming inactive dimers and higher molecular weight species.

Dynamic Characteristics of a Gyroscope and a Vibration Absorber

A two-degree-of-freedom gyroscope can't preserve its original direction when a housing on which the gyroscope is mounted oscillates. This problem has been dealt with by many people, but their works have been in want of universality in condition. In this paper, authors discuss the motion of a gyroscope mounted on a housing oscillating about an axis having arbitrary direction, and obtain the formulas of the drift rates by taking advantage of the fact that one can regard a two-degree-of-freedom gyroscope as a spherical quadric crank chain mechanism when the spin axis remains unchanged. And they investigate the effect of the dynamic unbalances of gimbals, the flexibility of a rotor shaft and frictions of bearings. And authors manufacture a gyroscopic vibration absorber for trial and examine its effect.

The Drifts of Gyroscope Mounted on the Oscillating Housing

It is a very important problem that the spin axis of a two-degree-of-freedom gyroscope can't preserve its original direction in case the housing on which the gyroscope is mounted oscicllates. The authors discuss the behavior of the spin axis of a gyroscope mounted on the oscillating housing, and analyze the phenomena theoretically and experimentally. In this paper the formulas of the drift rates are obtained by taking advantage of the fact that one can regard a two-degree-of-freedom gyroscope with two gimbals as a spherical quadric crank chain mechanism in case that the directioin of the spin axis remains unchanged. In the experimental section the drift rates and the amplitudes of the forced vibration are measured for various initial positions of both gimbals and forced frequencies, and resonance is investigated.

On the mechanism of carbon formation in flames

A physical model for carbon formation in flames is developed by assuming that positive ions serve as nuclei and that particles are ionized during growth and agglomeration. Analysis of the model predicts the well-known chained structure of carbon particles collected from flames and the uniform size and crystallite structure of the spherical chain units. The predicted size of the crystallites is essentially identical to the experimentally observed value of 20 to 30 A. The model is based on experimental information in the literature. The predicted structure of particles results from the effects of interparticle electrostatic forces during growth and agglomeration. The analysis includes calculation of the state of ionization of particles under typical flame conditions and calculation of the forces, and the resulting energy requirements for collision, between both dielectric (young) and conducting (older) particles.

Compressibility of Polymer Solutions

The compressibility of polymer solutions was measured by the ultrasonic method (in Mc range). The partial specific compressibility of polymer in the solution was determined, and they yielded information about the polymer in the solution.The information on the polymer were divided into the following two parts: (1) the response of a spherical polymer chain in the solution as a pearl necklace model, (2) the response of a mixing unit of the polymer chain as a pearl in necklace.The response of a spherical polymer chain was proportional to the intrinsic viscosity of each solution, and was related to the chain dimentions as the viscometric expantion parameter was. On the other hand, the compressibility of a mixing unit of the polymer was the specific value of each component.