4,594 research outputs found
Tris(n-octyl)arsine oxide as a reagent for liquid-liquid extraction
No full textThe extraction of HClO₄, HCl, HBr, HI, HNO₃, citric acid and the metal ions; iron(III), zinc(II), cadmium(II), hafnium(IV) and zirconium(IV) by tris(n-octyl)arsine oxide (TOCASO) in benzene was investigated. A survey of the qualitative extraction of some 40 metal ions was also reported. From saturation loading curves it was found that the proton to TOCASO ratio was 2:1 when the acids were extracted by 0.1 M concentrations of the reagent in benzene. In the HClO₄ system, the co-extraction of water was noted and the adduct was probably of the type TOCASO[proton symbol]H₃O[proton symbol]ClO[superscript negative sign, subscript 4]. Hydrochloric acid formed a 2:1 adduct with TOCASO at aqueous acid concentrations [greater than or equal to] 1.0 M. The HCl adduct was presumably of the type TOCASOHHCl[superscript negative sign, subscript 2]. Hydrobromic and hydroiodic acid formed 1:1 adducts at initial aqueous acid concentrations of 0.1 to 2.0 M. The co-extraction of one mole of water with each mole of acid was observed under these conditions. At HBr and HI concentrations [greater than or equal to] 4.0 M and [less than or equal to] 7.0 M formation of the adducts, TOCASOH�HBr[superscript negative sign, subscript 2] and TOCASOH�HI[superscript negative sign, subscript 2], was observed without co-extraction of water. Nitric acid formed a 1:1 adduct at initial acid concentrations of 0.1 to 1.0 M with co-extraction of water. As the nitic acid concentration was increased the ratio of reagent to acid increased, and concurrently, the ratio of water to acid decreased. At initial aqueous citric acid concentrations [greater than or equal to] 2.0 M the stoichiometry indicated a molar ratio of reagent to acid of 3:2. ..
Investigation of stresses in a plate containing circular holes
No full textIn this investigation, the magnitude and position of the maximum stresses, as well as the stress distributions (maximum sheading stress) of critical sections of large plates perforated by circular holes and subjected to two-dimensional hydrostatic tension, were determined by PhotoStress method. The plates tested had (1) four circular holes on a ring, (2) four circular holes on a ring with a central hole, (3) four circular holes on the first ring, and four circular holes on the second ring -- in parallel position, and (4) four circular holes on the first ring and four circular holes on the second ring -- 45��apart from parallel position. A series of tests, with different ratios of hole diameters to ring diameters have been performed in each case mentioned. The PhotoStress material used to make the models was Epon 828, a product of Shell Chemical Company. Only plastic plates have been used, and aluminum paint was sprayed on the bottom surface of the plastic model in order to make a mirror surface, which served the same purpose as an actual structural surface for the reflection of light. A technique for applying two-dimensional hydrostatic tensions on the periphery of a large p late was developed in order to carry out the investigation. Curves of stress distribution in dimensionless form have been plotted for the various sections in each PhotoStress model. Some comparisons were made between the experimental results and analytical values, whenever the latter were available
A study of administrative viewpoint in the role of student involvement in policy and decision-making at Texas colleges and universities
No full textThe purposes of the study were two-fold: (1) to assess students' existing and idealized roles in the policy and decision-making processes at the seventy-four senior Texas institutions and colleges offering advanced degrees, as seen by the respective college or university presidents and the chairmen of the governing boards; and (2) to determine the significance of the concept of change between presidents and chairmen of the governing boards in the implementation of processes of student involvement in policy and decision-making in the responding institutions. The population was the seventy-four college and university presidents and the fifty-eight chairmen of the governing boards of Texas colleges, universities, and institutions that were considered senior schools by The Coordinating Board, Texas College and University System. A modification was made of Paul R. Hensarling's Instrument for Evaluation of Student Involvement in High-School Policy Making. The survey questionnaire contained forty-eight statements organized in three major sections: I. Organization and Administration, II. Student Governance, and III. Rules and Regulations. Six null hypotheses were offered to be tested in the study. The first four compared the two parties in their perceptual viewpoint of the existing and ideal roles for student involvement in the decision-making processes in Texas colleges. The fifth hypothesis distinguished the difference between administrative attitudes, in relation to the purpose of the study, in the analysis of school population size, type of institutional support, and level of highest degree offered by an institution. The sixth hypothesis determined the significance of the concept of change between the two administrator groups in viewing student participation in their schools in the last five-year period. Statistical data were compiled on the first five hypotheses using analysis of variance, and a chi-square method was used to develop the sixth hypothesis. ..
Plasma electron thermalization measurements utilizing the spectral distribution of laser light scattered by plasma electrons
No full textThe Thompson-scattering method has been used to investigate the thermalization of plasma electrons in hydrogen, helium and argon plasmas. The thermalization measurements were made after the injection of the plasma into a semi-cusp magnetic field. The magnetic field was found to be effective in isolating the plasma while the thermalization measurements were made. The measurement of the temporal development of the plasma electron temperature yielded experimental results that were found to be in good agreement with the thermalization theory of Spitzer¹ and Sivukhin.² The results did, however, indicate a slower electron heating rate than is predicted by the theory. This effect is believed to have been caused by the loss of high energy electrons during the thermalization process
The effects of motivation on performance of individuals possessing selected personality characteristics
No full text[Purpose] The purpose of this study was to investigate whether the performance of an anaerobic task was affected by selected motivational techniques and whether the performance scores are related to selected personality factors. It was also the purpose of this study to determine if any performance differences brought about by the various motivational techniques were significantly different for Athletes and Non-Athletes. [Procedure] Six hundred and fifty male college freshmen completed a questionnaire constructed of thirty-five items from the Sixteen Personality Factor Questionnaire. Using the scores obtained on this questionnaire as criteria, one hundred and twenty subjects were selected, thirty representing each of the personality factors Schizothymia, Dominance, and Self-sufficiency, and thirty subjects representing the Control group. The subjects selected for this study were also identified as being either Athletes or Non-Athletes. Each subject was scheduled to meet with the investigator once a week for three consecutive weeks. At each meeting the subject was asked to perform a one minute all-out ride on the bicycle ergometer. The scores for each test were recorded in total pedal revolutions accumulated for the one minute period. Each test was performed under a different motivational technique. The three motivational techniques used in this investigation were: simple task instruction, simple task instruction and verbal reinforcement, and simple task instruction and competition. ..
A digital computer solution of a three-dimensional photoelastic study of a thick-walled cylindrical shell
No full textNo Abstrac
Absorption of resonance scattered gamma-rays as a method of measuring nuclear level widths
No full textA novel method for determining nuclear level widths is used in this investigation. Neutron capture gamma-rays from iron bombard a lead target. The incident 7.285 Mev gamma-rays cause resonance fluorescence of the Pb�������� in the target. The energy of the emitted gamma-rays varies continuously with the scattering angle as the result of the recoil energy is about 500 ev. The energy resolution is so well defined that a level width can be determined by measuring the resonance depression caused by an absorber placed in the scattered beam. The method is applied to the known level in lead and as self-absorption preformed. Only a portion of the resonance depression was observed since it is located near 0��and small angle Compton scattering interferes with the signal. The value observed for the width was 0.7 �� 0.2 ev which agrees with the measurements performed by other methods. Applications of the technique are suggested which should be of substantial value to the nuclear spectroscopist
Coupled reactors kinetics equations
No full textA general formulation of the kinetics equations of a system of coupled reactors is developed within the framework of neutron transport theory. The time behavior of the neutron population in a system of M interacting reactors is described by a set of M coupled generalized point kinetics equations. The kinetic behavior in each reactor being determined partly by its own characteristics and partly by the neutronic contribution from the rest of the system. The method of approach consists of describing the neutron population within a reactor by a single equation, the time dependent transport equation, and classifying neutrons on the surface of the reactor by groups according to the particular direction they travel with respect to a unit normal at the surface. This permits the use of the concept of surface coupling to account for the neutronic interaction between the reactors. To obtain the kinetics equation of the jth reactor in the system an adjoint equation is formulated in conjunction with the time dependent transport equation. The adjoint equation describes a fictitious steady state in the jth reactor when isolated from its environment. The mathematical procedure to derive the kinetics equations is basically the same as that used informulating generalized point kinetics equations. The coupled reactors kinetics equations are cast in terms of an amplitude time function and the reactor parameters defined as functions of a time dependent space flux shape. ..
Investigation of a three-component plasma streaming into a dipole magnetic field
No full textThompson scattered laser light has been used to determine time resolved electron temperature and density as a hydrogen plasma, with helium and argon ions in 25 and 10% concentrations, drifted into a dipole magnetic field. Doppler broadening of the H (subscript alpha) line yielded data on the hydrogen ion temperature. The plasma was not trapped and was not monitored while drifting through the dipole cusp. A two-phase plasmoid model is proposed in order to explain the behavior of the observed densities and temperatures. A given plasmoid is followed from its initiation until it passes the observation point while undergoing a collisionless transfer of directed ion energy to cyclotron energy due to the magnetic field gradient and then thermalizing through coulomb collisions. Calculations using this model approximate the observed behavior and the trends pertinent to the effect of the heavy ions added as impurities
- …
