Experimental Studies on Plant Metabolism

Treatment of Ricinus communis seeds with GA accelerated the production of reducing sugars and increased the total carbohydrate content. The effect increased progressively with increasing concentration of GA. — GA treatment also induced an earlier appearance of starch which was shown to be completely absent at the early stages of germination. Furthermore, GA accelerated the conversion of oils into carbohydrates. — Analysis of germinating seeds for their nitrogen content showed that whenever an increase in soluble-N due to GA treatment was detected, there was a decrease in protein-N. Breakdown of protein and formation of soluble-N increased progressively with increase in GA concentration. — GA induced variable changes in the length of the radicles and the hypocotyls, the dry weight and the water content of germinating seeds.     

Experimental and Simulation Studies of Electro-rheology

Abstract

Electro-rheological fluids are colloidal dispersions that, under the influence of an applied electric field, can show a spectacular increase in yield stress and viscosity. Despite many technological roles for fluids with a viscosity that can be controlled electrically, progress at making them commercially viable products has been slow, partly due to a lack of understanding of this phenomenon at the microscopic level. In this report, simulation and experimental data are combined to provide insights into the microscopic origins of this effect. The simulations produce electric field-induced “strings” of particles that span the electrodes, in agreement with the experimental observation, and are responsible for the major enhancements in the viscosity. The field also causes a strong distortion in the first coordination shell of colloidal particles. The combination of shear and electric field produces a long-range microstructure that is periodically forming and decaying, caused by the competing effects of electric field and shear rate. Comparison with experiment reveals that the Electro-rheological effect is driven by the applied field-induced Stokesian diffusion of the solid particles and relies little on the accompanying Brownian motion.     

Experimental Studies of Apospory in Ferns

Apospory in Pteridium aquilinum was found to have several novelfeatures, in particular the rapidity of its occurrence. Outgrowthsfrom detached laminae were detected in as little as 3 days.There was no evidence that failure of co-ordination betweencells, senescence of the sporophytic tissue or unfavourableculture conditions effected the initiation of outgrowths asearlier workers have suggested. The response of Thelypterispalustris was notably slower and more in line with earlier reportsof apospory. Marsilea vestita appeared to be incapable of anyform of aposporous behaviour. The only feature common to all occurrences of apospory in leavesof wild-type ferns is the severance of the lamina from the mainbody of the plant. It is proposed that this may deprive thecells of regulatory substances which maintain the activationof sporophytic genes. The results are also considered in relationto the phase changes in homosporous and heterosporous plantsand the behaviour of fern protoplasts in culture. apospory, ferns, Pteridium aquilinum, Marsilea vestita, Thelypteris palustris     

Studies on Infectious Mononucleosis: II: Attempts at Experimental Transmission to Monkeys

Heparinized blood specimens obtained from two patients in the acute phase of infectious mononucleosis and from a healthy technician were injected intravenously into rhesus monkeys (Macaca mulatta) and the animals were observed for three weeks to one month for clinical, hematological and serological signs of infectious mononucleosis.Splenomegaly was the only definite clinical finding after 12 and 16 days, respectively. There were no definite hematological changes.At autopsy, hyperplasia of the germinal centres of lymphoid follicles, occasional foci of lymphocytic infiltration in the red pulp, and abnormal lymphoid cells in venules or arteries of the spleen were noted.The lesions in the spleen suggest that asymptomatic, presumably viral, infections occur in rhesus monkeys after inoculation with material from patients with infectious mononucleosis.     

Studies on the Structure of Feather Keratin: I. X-Ray Diffraction Studies and Other Experimental Data

Previous data as well as new results are examined with a view to determining the boundary conditions which present experimental information places on a satisfactory polypeptide chain model for the structure of feather keratin. Our studies indicate these conditions to include the following: (1) A 189 A identity period, with a pseudoidentity of 94.5 A; (2) characteristic fiber axis periodicities of 23.6₄, A and 18.9 A; (3) a meridian reflection of 2.96 A, but none in the 1.0 A region; (4) a strong, but sensitive, equatorial reflection of about 33 A spacing, with a possible equatorial reflection near 50 A; (5) perpendicular infrared dichroism of v (NH) of at least 5:1; (6) a limited extensibility along the fiber axis direction; (7) the natural accommodation of about 12 per cent of proline residues in the structure; (8) the possibility of breaking down the structure into units of about 10,000 molecular weight. The implications of these conditions with respect to a satisfactory model are considered.     

Experimental and Theoretical Studies of Calcium Fructoborate

Calcium fructoborate samples of composition Ca(C₆H₁₀O₆BO)₂·3.5H₂O were characterized by chemical analysis, infrared and Raman spectroscopy, and thermoanalytical (thermogravimetric and differential thermal analysis) data. Theoretical studies, using density functional theory, were made for seven different structural models of the fructoborate moiety, and the most stable structure could be derived from these calculations. The results of the theoretical study also allow improving the assignment of the vibrational spectra of the compound.