Separation of serotonin from catechols by capillary zone electrophoresis with electrochemical detection

Capillary zone electrophoresis with electrochemical detection is demonstrated with columns having only 9-microns inner diameter. Amperometric detection limits of 0.7 amol are reported for serotonin. The difficult problem of resolving serotonin and dopamine--two neurotransmitters of interest having similar electrophoretic mobilities--is addressed by chemical means to improve selectivity. These include buffer modification with 2-propanol and a system employing borate complexation of the catechol in combination with sodium dodecyl sulfate micelles.     

Time series analysis of wind speed using VAR and the generalized impulse response technique

This research examines the interdependence in time series wind speed data measured in the same location at four different heights. A multiple-equation system known as a vector autoregression is proposed for characterizing the time series dynamics of wind. Additionally, the recently developed method of generalized impulse response analysis provides insight into the cross-effects of the wind series and their responses to shocks. Findings are based on analysis of contemporaneous wind speed time histories taken at 13, 33, 70 and 160 ft above ground level with a sampling rate of 10 Hz. The results indicate that wind speeds measured at 70 ft was the most variable. Further, the turbulence persisted longer at the 70-ft measurement than at the other heights. The greatest interdependence is observed at 13 ft. Gusts at 160 ft led to the greatest persistence to an “own” shock and led to greatest persistence in the responses of the other wind series.     

Investigation of fusion reactions in palladium and titanium tritide using galvanostatic,coulometric, and hydrogen permeation techniques

We describe several electrochemical methods used to investigate the possibility of cold fusion phenomena in palladium and titanium tritide cathodes. We performed long-term (up to 77 days) electrolysis experiments with electrochemical cells of the University of Utah type at current densities as high as 1 A/cm², while monitoring neutron and tritium levels. With some cells, we pulsed the current to determine if neutron bursts would result. In another cell, we used titanium tritide as the cathode to determine if D-T reactions yielding neutrons would occur. In no instance were levels of neutrons or tritium significantly above background except in the titanium tritide cell where isotopic exchange, occcurring between the electrode and the electrolyte, resulted in significant tritium levels. We also combined x-ray photoelectron spectroscopy (XPS) and electrochemical hydrogen permeation experiments to determine the effectiveness of various Pd surface treatment procedures on the resultant electrochemical hydrogen absorption efficiency. Electroanalytical and thermal desorption/gas analysis techniques indicated the maximum loading of H in Pd was to a ratio of HPd=0.8.     

Power up! Using Digital Gaming Techniques to Enhance Library Instruction

ABSTRACT

Incorporating digital gaming into education is an increasingly popular topic in academia. Educators’ views of digital gaming (e.g., computer, video, and online games) have shifted from categorizing these games as an entertaining, yet pedagogically void activity to a promising medium that engages students in the learning process. With over 70% of college students enthusiastically playing digital games, educators are tapping into digital gaming as an effective means to teach millennials problem solving and communication skills. This article investigates gamer characteristics, motivational and engaging aspects of digital games, and the parallels between gaming and the information retrieval process. The authors build on this information to present approaches to incorporate digital gaming techniques into the library classroom since it is not feasible for all libraries to create instructional digital games.     

Detection of low levels of trichloroethylene vapor with Raman spectrometry

The response of a novel fiber-optic Raman probe to low levels of trichloroethylene (TCE) vapors is characterized. The detection limit of the current probe for TCE vapor is 34 mg/L, and the probe exhibits a fully reversible response. The probe uses an organic-polymer, low-density polyethylene to concentrate TCE vapors in the optical path of the fiber-optic Raman spectrometer. The relative standard deviation for measurement of 677 mg/L of TCE in the vapor is 0.3%.     

Degenerate Two-Phase Incompressible Flow IV: Local Refinement and Domain Decomposition

This is the fourth paper of a series in which we analyze mathematical properties and develop numerical methods for a degenerate elliptic-parabolic partial differential system which describes the flow of two incompressible, immiscible fluids in porous media. In this paper we describe a finite element approximation for this system on locally refined grids. This adaptive approximation is based on a mixed finite element method for the elliptic pressure equation and a Galerkin finite element method for the degenerate parabolic saturation equation. Both discrete stability and sharp a priori error estimates are established for this approximation. Iterative techniques of domain decomposition type for solving it are discussed, and numerical results are presented.     

Radiation and thermal effects on porous and layer structured materials as getters of radionuclides

The long term radiation and thermal effects on porous and layer structured materials that may function as getters for radionuclides have been evaluated using accelerated laboratory experiments including energetic electron, ion or neutron irradiation, as well as high-temperature thermal annealing. The materials studied include: zeolites, layered silicates (mica and smectite clays), open framework structured apatite and crystalline silicotitanate (CST) which is an important synthetic ion-exchange material for the chemical separation of high-level liquid radioactive wastes.In situ transmission electron microscopy during irradiation by energetic electrons and ions has shown that all the studied materials are susceptible to irradiation-induced amorphization. Amorphization can be induced by ionization and/or direct displacement processes. Amorphization may be preceded or accompanied with dehydration, layer spacing reduction and gas bubble formation. In the case of zeolites, CST and some layer silicates, radiation effects are significantly enhanced at higher temperatures. In fact, thermal annealing at high temperatures alone can cause complete amorphization of zeolites. Our experiments have shown that amorphization or even partial amorphization will cause a dramatic reduction (up to 95%) in ion-exchange and sorption/desorption capacities of zeolite for radionuclides, such as Cs and Sr. Because the near-field or chemical processing materials (e.g., zeolites or CST) will receive a substantial radiation dose after they have incorporated radionuclides, our results suggest that radiation effects may, in some cases, retard the release rate of sorbed or ion-exchanged radionuclides.     

Calorimetric and thermodynamic analysis of palladium-deuterium electrochemical cells

An analysis is made of the chemical heats liberated from a palladium-deuterium electrochemical cell operating inside a calorimeter. It is important, in such an analysis, to carefully identify the chemical and electrochemical sources of heat, before any “excess heats” can be ascribed to non-chemical reactions.⁽¹⁾ The calorimeter measures the enthalpy (ΔH _r ) of the reaction; whereas, the electrochemical voltage of the cell reflects the free energy (ΔG _r ) of the reaction within the Pd-D electrolysis cell. The heat energy from the calorimeter cell therefore doesnot equal the electrical energy supplied to the cell, as might initially be expected. The magnitudes of the differing calorimetric and electrochemical energies were found to be related through the “thermoneutral potential” (ξ_H) of the electrochemical reaction. The chemical heat theoretically expected from the calorimeter is given by (1) I(ξ_L-ξ_H), the cell current (I), multiplied by the difference between the operating cell voltage (ξ_L) and the thermoneutral potential (ξ_H), rather than (2) Iξ_L, the electrical input power. This was verified empirically using a freon vaporization calorimeter, which operates on the principle of accurate measurement of the vaporization rate of liquid freon which completely surrounds the electrochemical cell. The calorimetrically-measured heats observed from a Pt/D₂O, 0.1M LiOD/Pd electrochemical cell were within 2% of the thermoneutral potential predicted value, I(ξ_L-ξ_H); but were found to be 15–30% less than the electrical work supplied to the cell, Iξ_L. Measurements of D₂O consumed by the cell reactions also verified that essentially no significant recombination of D₂ and O₂ gases occurred within the cell. No “excess heats” were observed from this Pd cell during the 36 days of its electrolytic operation. Likewise, no increase in the neutron flux around the cell was found, using three³He radiation detectors.     

A Galerkin procedure for systems of differential equations

A continuous time and an extrapolated coefficient Crank-Nicolson-Galerkin method are considered for approximating solutions of boundary and initial value problems for a quasi-linear parabolic system of partial differential equations which is coupled to a non-linear system of ordinary differential equations. A priori bounds are derived that reduce the estimation of error to problems in approximation theory. Then approximation theory results yield optimal order rates of convergence for theH ¹ (Ω) norm. The extrapolated coefficient method yields linear algebraic equations for strongly non-linear problems. this research was supported in part by the National Science Foundation Grant No. MCS 75-21317 and Energy-related Postdoctoral Fellowship at the University of Chicago.