Twisted Radio Waves and Twisted Thermodynamics

We present and analyze a gedanken experiment and show that the assumption that an antenna operating at a single frequency can transmit more than two independent information channels to the far field violates the Second Law of Thermodynamics. Transmission of a large number of channels, each associated with an angular momenta ‘twisted wave’ mode, to the far field in free space is therefore not possible.     

Epoxidation in lyotropic mesophases

Summary The influence of the surfactant structure and water content on the epoxidation of propene to R- propene oxide withMycobacterium strain E3 immobilized in lyotropic mesophase/hexane two phase systems has been studied.     

Determination of molybdenum and tungsten in biological materials

A spectrophotometric method for the quantitative determination of molybdenum and tungsten in the presence of each other in biological materials, has been developed. The method involves the selective formation and extraction of the complexes of the metals with 4-methyl-1,2-dimercaptobenzene under specified conditions of acidity and temperature. Possible interference by components found in biological materials, was examined and shown to be negligible.     

Formation of fibrous materials from dense calcium caseinate dispersions

Application of shear and cross-linking enzyme transglutaminase (Tgase) induced fibrous hierarchical structures in dense (30% w/w) calcium caseinate (Ca-caseinate) dispersions. Using Tgase was essential for the anisotropic structure formation. The fibrous materials showed anisotropy on both micro- and macroscale as determined with scanning electron microscopy (SEM) and mechanical analyses, respectively. SEM revealed protein fibers with a diameter of approximately 100-200 nm; visually, we observed fibers of about 1 mm. Both shear and Tgase affected the reinforcement of the fibers to a large extent, whereas the mechanical properties in the direction perpendicular to the shear flow remained constant. Shearing Ca-caseinate without Tgase yielded a slightly anisotropic layered structure. Both cross-linking in the absence of shear and cross-linking during mixing resulted in gels without alignment. The formation of shear- and enzyme-induced anisotropic structures was explained by aligning of protein aggregates due to shear and concurrent solidification of the aligned protein aggregates.     

Micromanipulation measurements of biological materials

Micromanipulation enables the mechanical properties of microscopic biological particles to be measured in particular cells. It is capable of measurements at high deformations, including up to cell bursting. Particles as small as 1 m, with breaking forces as low as 1 N, can be characterised. The method can be enhanced by mechanical modelling to allow intrinsic mechanical properties such as the cell wall elastic modulus to be estimated. Present and potential applications include studying yeast and bacterial cell disruption, mechanical damage to animal cells in suspension cultures and filamentous microorganisms in submerged fermentations, plant cell behaviour in food processing, and flocculation processes.     

Spectrophotometric assay for diphenylthiohydantoin in biological materials

A new method for the determination in tissues of DPTH, a potent antagonist of thyroxine, has been developed based upon the strong uv absorbance characeristic of the thiohydantoins. Substances present in tissue homogenates which would interfere with the DPTH assay by virtue of their uv absorbance characteristics have been eliminated by means of a simple two-step extraction procedure. The important parameters affecting the specificity and efficiency of the extraction conditions procedure have been identified; considerable latitude in the choice of extraction conditions allows a high degree of adaptability to individual requirements. The assay protocol currently used in our laboratory involves extraction of the DPTH-containing tissue with xylene followed by the extraction of the xylene with 1.0 n NaOH. After removal of traces of dissolved xylene from the DPTH-containing alkali solution by bubbling with N₂, its DPTH concentration is calculated from the absorbance at 264.5 nm. DPTH concentrations in rat tissues as a function of time after a single oral dose have been determined.