Numerical analysis and experimental validation of planar electrorefiner for spent nuclear fuel treatment using a tertiary model

To improve the uranium recovery rate in pyroprocessing, it is crucial to develop a planar-type electrorefiner. This can be achieved prior to actual experiments by using computer simulations to analyze the shape, arrangement, and size of the cathode. In this paper, tertiary-model-based computational analysis was performed on a planar-type electrorefiner. Flat-plate and rod-type cathodes were analyzed under constant-current condition; calculations were performed on high-efficiency-type electrodes with convection effects under the same conditions by comparing the dependence of the generated overpotential on the applied current. Analytic and experimental results were analyzed by comparing the electric potential of the plate-type device with that of a uranium electrorefiner while varying the arrangement of the electrodes.     

Running a Profitable Construction Company: Revisited Break-Even Analysis

Many companies have a tendency to spread out their operations into branches and∕or separate corporations. The construction industry is a good example. With work being slow in some areas, it is sometimes more profitable to spread out the company into different areas in order to absorb more work and therefore create branches to the main office. When this is done, it is important to centralize these branches and analyze them as a whole to help the corporation. In this process, the break-even analysis can be used to help analyze the operations. Consideration for a corporation having one or more branches involved in several projects takes time and teamwork. The team that is organized to help in the decision-making process needs a plan to determine how the project will affect the company and other jobs that are already in progress. With one corporation having two or more branches, it can be difficult to figure out where the company as a whole needs to be in order to turn a profit. The team must consider what each branch is doing in volume and what their break-even points are. This comes down to an important point of this research, which is “where to break even” before the profit consideration is made. This research provides an exemplary application of the break-even analysis to an actual construction company with one or more branches.     

Plastic ELISA-on-a-chip based on sequential cross-flow chromatography

A plastic chip that can perform immunoassays using an enzyme as signal generator, i.e., ELISA-on-a-chip, was developed by incorporating an immunostrip into channels etched on the surfaces of the chip. To utilize an analytical concept of cross-flow chromatography, the chip consisted of two cross-flow channels in the horizontal and vertical directions. In the vertical channel, we placed a 2-mm-wide immunostrip for cardiac troponin I (cTnI), which was identical to a conventional rapid test kit except for the utilization of an enzyme, horseradish peroxidase (HRP), as tracer. An enzyme substrate supply channel and a horizontal flow absorption pad compartment were transversely arranged on each lateral side of the signal generation pad of the strip, respectively. Upon application of a sample containing cTnI, it migrated vertically through the membrane strip by capillary action, and antigen-antibody binding occurred. After 15 min, the horizontal flow was initiated by the addition of a chromogenic substrate solution for HRP into the supply channel and by partial superimposition of the horizontal flow absorption pad onto the signal generation pad. A color signal proportional to the analyte concentration was produced on this pad, measured after 5 min as optical densities using a digital camera-based detector, and quantified by integration of the densities under the peak after normalization. Its calibration curve indicated that the detection limit of the chip was approximately 0.1 ng/mL and its quantification limit was 0.25 ng/mL. In measuring blindly prepared samples, the chip performance correlated with that of a reference system, Beckman Coulter Access, within 2.5-fold discrepancy at the detection limit.     

A study of carbon-nanotube-based nanoelectromechanical resonators tuned by shear strain

This paper has investigated, using a classical molecular dynamics simulation method based on the Tersoff-Brenner potential, the resonance-frequency changes of single-walled carbon-nanotube resonators originating from the purely mechanical response of single-walled carbon nanotubes. The tension decreased with increasing rotation angle, so the resonance frequencies could be changed by controlling the rotation angles of the single-walled carbon nanotubes. The resonance frequencies decreased with increasing angle, and when the rotation angle was greater than 60°, the changes were marked. For nanotubes of similar length, the bandwidth for the (3, 3) single-walled carbon nanotube was higher than for the (5, 0) single-walled carbon nanotube. Because properties arising from the shear-strain-induced tension response can affect the electromechanical behavior of carbon nanotubes, the shear-strain-induced tension response should be given serious consideration in the application of embedded carbon nanotubes in nanoelectromechanical systems.     

Optical and Dielectric Properties of Chalcogenide Glasses at Terahertz Frequencies

Terahertz time‐domain spectroscopy has been used to study the optical and dielectric properties of three chalcogenide glasses: Ge₃₀As₈Ga₂Se₆₀, Ge₃₅Ga₅Se₆₀, and Ge₁₀As₂₀S₇₀. The absorption coefficients α(ν), complex refractive index n(ν), and complex dielectric constants ?(ν) were measured in a frequency range from 0.3 THz to 1.5 THz. The measured real refractive indices were fitted using a Sellmeier equation. The results show that the Sellmeier equation fits well with the data throughout the frequency range and imply that the phonon modes of glasses vary with the glass compositions. The theory of far‐infrared absorption in amorphous materials is used to analyze the results and to understand the differences in THz absorption among the sample glasses.     

Adsorption of cobalt(II) ion by titanium-based oxides in high temperature water

Titanium-based adsorbents such as TiO₂ and Fe-Ti-O were prepared by hydrolysis of Ti(OC₃H₇)₄ and alkalinizing an equimolar mixed solution of TiCL₄ and FeCl₂ followed by heat treatment of their hydroxides, respectively. The prepared Fe-Ti-O adsorbent was found to be stable nonstoichiometric ferrous and ferric titanium oxides with pseudobrookite and rutile structures. The Co²⁺ adsorption characteristics of the adsorbent in high temperature water were investigated in the autoclave.Co ²⁺ adsorption capacity of the Fe-Ti-O adsorbent was determined to be larger man that of TiO₂ at high temperatures. The enthalpy changes of 34 and 49 kJ-mol^-1 due to the adsorption of Co²⁺ on the TiO₂ and Fe-Ti-O adsorbents indicate that the adsorption is endothermic in the experimental temperature range (15-280 ‡C). From this preliminary study, titanium-based oxides are shown to have good potential applicability for reactor water purification as high temperature adsorption media.     

Numerical heat transfer analysis for the design of the engineering-scale electrowinning cell in pyroprocessing

A heat transfer analysis of the electrowinning cell was conducted to develop a basic tool for designing of the engineering-scale electrowinner. For calculating the heat transfer properties of argon gas and LiCl–KCl eutectic salt in the electrowinning cell, the ANSYS CFX commercial code was adapted. The simulation model was prepared, and the temperature profiles of the argon gas and the salt were compared with those in the lab-scale electrowinning cell. Using the simulation model, temperature distributions of the engineering-scale electrowinning cell were analyzed. When the heating zone length was 2.5 times longer than the height of the LiCl–KCl salt, the salt temperature was maintained at about 500 °C and its temperature gradient became less than 5 °C. The cooling zone length had an influence on both temperatures of the argon gas under the cell cover as well as the salt. When the cooling zone length was about 0.16–0.19 of the heating zone length, the temperature of the salt was maintained at 500 °C and the argon gas temperature under the cover decreased below 200 °C. The number of the heat shield plates and size mainly affected the temperature gradient of the salt and argon gas under the cover. More than 3 heat shield plates had to be placed in the cooling zone and their diameters should be extended over 410 mm that is over 0.95 of the cell diameter.     

Thermodynamic Relation between Silicon and Aluminum in Liquid Iron

The thermodynamic relation between silicon and aluminum in liquid iron was studied by measuring the effect of silicon on the solubility product of AlN in liquid Fe-Si-Al-N alloys containing silicon up to 1.5?mass pct in the temperature range from 1823?K to 1923?K (1550 °C to 1650 °C). The effects of aluminum and silicon on nitrogen solubility in liquid iron were separately determined in the same temperature range. The experimental results were thermodynamically analyzed using Wagner??s interaction parameter formalism to determine the first-order interaction parameters of silicon on nitrogen and aluminum in liquid iron as follows: $ e_{\text{N}}^{\text{Si}} = 0. 0 6 7 3, \;e_{\text{Al}}^{\text{Si}} = 0.009 $ (1823?K to 1923?K (1550 °C to 1650 °C), Si ?? 1.5?mass pct)     

On-Site diagnostic device based on immuno-separation of proteins

A membrane immuno-chromatographic system that selectively separates plasma lipoproteins and generates a signal in proportion to the concentration of cholesterol (HDL-C) within high-density lipoprotein (HDL) was investigated as a point-of-care device for the prognosis of coronary heart disease. The system consists of three functional membrane strip pads connected in a sequence for: (from the bottom) immuno-separation based on biotinstreptavidin reaction, catalytic conversion of cholesterol to hydrogen peroxide, and production of a signal. For immunochromatography, a monoclonal antibody, specific to apolipoprotein B100 that is present on the surfaces of low-density lipoproteins (LDL) and very low-density lipoproteins (VLDL), with a high binding constant (5xl0¹⁰ L/mol) was raised and chemically conjugated to streptavidin. The conjugate was first reacted with lipoprotein particles, and this mixture was absorbed by the capillary action into the biotin pad of the system. After being transferred by medium, immunocapture of LDL and VLDL particles onto the biotin pad took place, andin situ generation of a signal in proportion to HDL-C consecutively occurred. The capture was selective as well as effective (minimum 90% of LDL and VLDL in clinical concentration ranges), and the detection limit of HDL-C was far lower than 20 mg/dL. To construct a userfriendly device, we are currently investigating the automation of such processes of reactions and separation by adapting a liquid flow-controlling technology that programs the times for the immune reaction and separation. My group further pursues an interdisciplinary study to develop a micro system employing semiconductor-based technologies that will eventually enable the handling of sub-micro liter volume of body fluid as a specimen.