The laser-induced birefringence has been studied as a function of temperature, time and equivalent field strength. The method is illustrated for the log—normal distribution and simple analytic expressions are derived for a variety of rigid particle shapes. Preliminary data are given for slurries of disc-like and brick-like particles up to 33% solids content. An apparatus has been built with which one can measure the changes in both the spectral characteristics and the intensity of the light scattered from aqueous solutions and suspensions. Both homogeneous and homeotropic films have been studied in a light microscope as a function of the orientation of polarised light and using both crossed and parallel polariser and analyser. During the next half century, occasional measurements were made both to characterise the phenomenon and to evaluate the relevant physico-chemical parameters of pure liquids and molecular fluids.
Measurements have been made on suspensions of Escherichia coli and Thiobacillus ferrooxidans chosen as model systems. In this note we report how, by measuring the intensity of the scattered light, the electric polarisability alpha of Escherichia coli could be monitored as small quantities of antibiotics were added to the suspensions. The present volume contains the texts of all of the invited lectures presented at the Institute. A comparison between any two sets of experimental data leads to estimation of the minor particle dimension and a quantitative measure of the particle non-sphericity. The method is developed for dilute and polydisperse suspensions of constant thickness disc-like particles. These were analysed in terms of theories for rigid rods, weakly bending rods and worm-like chains.
Differences have been noted in the responses of the sensitive form to different aminoglycosides and an attempt has been made to correlate these differences with mimimum inhibitory concentrations. The effect of the presence of quite small quantities of antibiotic on the electrical polarisability, which gave rise to the induced dipole, was dramatic. This is attributed primarily to interfacial origins. Illustrative data are presented for the effect of alcohols, antibiotics, urea, formaldehyde, cetyltrimethylammonium bromide, and sucrose, on suspensions of the organism Escherichia coli. This is consistent with the presence of interacting rod micelles. The possible role of F-actin in muscle contraction is discussed.
By extending the wavelength lambda of the incident radiation into the infrared, we show that the effective size of the bacteria relative to lambda is reduced, and the usual Zimm plot measurements and procedure can be applied to evaluate the molecular weight and size. The second part highlights the unique advantage of using electro-optics as an alternative to conventional characterization and analysis of colloidal systems. Low-frequencyanomalous electro-optic behavior of colloidal systems sign reversal and deviations from Kerr low is considered in the light of electrically induced acoustic modes. For a suspension at room temperature, a pH of 6·8 and with a specific conductivity of 11·8 × 10-4 ohm m -1, the surface polarizability depended upon l 1·8 with l the particle length. The ratio of these diameters is a function of the axial ratio alone for ellipsoids, rods and discs. A study is reported on a dilute aqueous suspension of the hollow rod particles of halloysite. Demonstrating the sensitivity of electro-optic methods to interparticle interactions, the book explains how these methods are used to analyze particle surface electric states, evaluate phase transitions, and determine physical properties.
Molecular electro-optics is a difficult subject for research because it incorporates areas of theoretical physics such as elec tromagnetic theory and hydrodynamics of rotational diffusion, ex perimental physics such as lasers, optics, electric pulsers, and data collection via analog to digital converters and signal aver agers, and physical chemistry of macromolecules and colloids in solution colloid science, biophysical chemistry, double layer polarization. Author by : Erhard W. Electrically induced changes in the intensity of scattered visible electromagnetic radiation, from polydisperse aqueous suspensions of rod-like bacteria, can not lead to exact information on the electrical parameters of the bacteria because the suspensions do not satisfy the Rayleigh—Gans—Debye approximation limiting conditions. The apparatus is particularly relevant to non-spherical particles and is applicable to both dilute and concentrated media. The technique has been tested by measurements on polydisperse suspensions of Escherichia coli in water. This site is like a library, you could find million book here by using search box in the widget. A procedure is developed, based on experimental transient electric birefringence data, for the evaluation of the length dependence of the interfacial component of the electrical polarizability for polydisperse, dilute solutions of rod-like molecular particles.
It is suggested that this parameter may be of value a to indicate the molecular weight at which the flexibility is significant, and b as an indicator of the relative flexibility of different members of the polysaccharide family. The fluid is held between suitable electrodes. This technology was applied to producingnovel materials, for example organic-inorganic hybrids, which are quite difficult to make by other fabricating techniques, and it was also applied to producing materials based on high temperature superconducting oxides. The latter were recently detected and investigated in samples of isotropic spherical particles. A convenient additional average parameter is the translational diffusional coefficient obtained from scattered intensity fluctuation spectroscopy. Industrial contri buters consisted of the General Electric Company, Cober Electronics, and Malvern Scientific Corporation.
It is shown that, for the decay process, the initial slopes of the natural logarithm of the normalised birefringence versus time curves for transients obtained under two discrete experimental conditions provide sufficient data to describe the spread in particle size in terms of two-parameter distribution functions. Please click button to get electro optics and dielectrics of macromolecules and colloids book now. This Advanced Study Institute was attended by sixteen invited lecturers and by forty-eight other participants. Proteoglycan solutions contain a certain amount of dimer whose presence may be of significance in arthrotic disorders. The last mentioned enable the experi menter to study the Kerr effect not only for its amplitude but also in the time domain. The theory for this concept was formulated by Langevin.
Ohtsu in 1993, this volume begins with theories for operation principles of characteristic nanophotonic devices and continues with novel optical near field phenomena for fabricating nanophotonic devices. Author by : Stoyl P. For poly r A and poly r C the effects are found to depend strongly upon the polymer concentration. The absence of any permanent dipole moment is highlighted in its implications on the packing geometry of the molecules within the crystallites. A method is presented for analysing measurements made using a photon correlator of the light scattered by polydisperse suspensions of colloids or solutions of rigid macromolecules.
Electric fields were imposed on aqueous suspensions of the rigid asym- metric particles of crocidolite. Both the rotary relaxation times obtained from transient time dependent effects and the amplitudes of the observed birefringence have been analysed in terms of theories for rigid rods, weakly bending rods, worm-like chains and both flexible and stiff random coils. Bacteria in suspension may be oriented by the action of applied electric fields owing to the presence of dipole moments that are associated with the bacteria. Two types of polymer sample were studied. The persistence length concept does not appear to be adequate when rotary relaxation times are interpreted through it using current equations. In this equation, m is the ratio of the refractive index n of the solute to that of the solvent n 0.