Simulation of a 2-site Langmuir model for characterizing the sorption capacity of Cs and Se in crushed mudrock under various ionic strength effects

The sorption capacity of cesium (Cs) and selenium (Se) in crushed mudrock was demonstrated in this study through a 2-site Langmuir model. To employ such a numerical analysis, batch tests were applied in this study in synthetic seawater and groundwater with sorption/desorption kinetic experiments (time-dependent) and different concentrations (10^?2–10^?7 M). The 2-site sorption models, which correspond to two rate constants (λ ₁ and λ ₂), might be more adequate than 1-site sorption models in characterizing Cs and Se sorption/desorption according to the least square errors between the numerical analysis and the results of the batch tests. The fitting results showed that a 2-site Langmuir model is capable of appropriately describing Cs and Se sorption in mudrock. Consequently, the sorption capacity was calculated at about 0.06 mol/kg for Cs and at 0.015 mol/kg for Se.     

A CSP and tabulation-based adaptive chemistry model

We demonstrate the feasibility of a new strategy for the construction of an adaptive chemistry model that is based on an explicit integrator stabilized by an approximation of the Computational Singular Perturbation (CSP)-slow-manifold projector. We examine the effectiveness and accuracy of this technique first using a model problem with variable stiffness. We assess the effect of using an approximation of the CSP-slow-manifold by either reusing the CSP vectors calculated in previous steps or from a pre-built tabulation. We find that while accuracy is preserved, the associated CPU cost was reduced substantially by this method. We used two ignition simulations – hydrogen–air and heptane–air mixtures – to demonstrate the feasibility of using the new method to handle realistic kinetic mechanisms. We test the effect of utilizing an approximation of the CSP-slow-manifold and find that its use preserves the order of the explicit integrator, produces no degradation in accuracy, and results in a scheme that is competitive with traditional implicit integration. Further analysis on the performance data demonstrates that the tabulation of the CSP-slow-manifold provides an increasing level of efficiency as the size of the mechanism increases. From the software engineering perspective, all the machinery developed is Common Component Architecture compliant, giving the software a distinct advantage in the ease of maintainability and flexibility in its utilization. Extension of this algorithm is underway to implement an automated tabulation of the CSP-slow-manifold for a detailed chemical kinetic system either off-line, or on-line with a reactive flow simulation code.     

Shortening of travelling-wave-amplified spontaneous emission by a transversal pumping scheme

An experimental investigation on shortening of travelling-wave ASE employing a transversal pumping is presented. A N₂ laser with =337.1 nm, pulsewidth: 700 ps is used as a pump source. An ASE pulse with duration of 45, 55 and 45 ps from dye solution of Rh 6G, Rh B and C311, respectively, is obtained. Pulse shapes of output signals generated from these solutions in three different pumping schemes are compared.     

The general three-vertex,BRS identities and renormalizability of the light-cone gauge

The general one-loop three-vertexГ _μeλ ^abc (p, q, r) in the four-component formulation of the Yang-Mills theory is calculated in the light-cone gauge. The nonvanishing counter Lagrangian constructed from this three-vertex and the self-energy is proportional to the original Lagrangian, the single renormalization constant being -11g² C _YM Г(2?ω)/48π². Gauge dependent and nonlocal counterterms do not contribute to the renormalization constant, but are needed to verify the appropriate Slavnov-Taylor (ST) and Becchi-Rouet-Stora (BRS) identities.     

The proposed Penning trap mass spectrometer facility at TASCC

The proposed Penning trap mass spectrometer, to be located at the TASCC facility of the Chalk River Laboratories, is described. The facility will be used for precise atomic mass determinations among both stable and unstable nuclides. The unstable nuclides would be produced in heavy ion reactions using the TASCC facility. The products from these reactions would be collected using an He-jet transport system loaded with NaCl aerosols. After transport to a background free area, the nuclides of interest would be laser desorbed and resonantly ionized. Subsequently, these ions would be accumulated in a Paul trap, cooled and injected into a precision Penning trap mass spectrometer for mass analysis.     

Analysis of Quantum Rod Diffusion by Polarized Fluorescence Correlation Spectroscopy

To measure the polarization dependence of fluorescent probes, a confocal-microscope-based polarized fluorescence correlation spectroscopy system was developed, and the polarization dependence on the rotational diffusion of well-defined quantum rods (Qrods) was investigated and characterized. The rotational diffusion region of the Qrods was observed over a time range of less than 10^?5 s in a water solution, and the rotational diffusion parameters were extracted using a rotational diffusion model in which the viscosity of the solution media was varied. Our work demonstrated that polarized fluorescence correlation spectroscopy (FCS) is useful for investigating both the rotational and translational diffusion of fluorescent probes.