Dielectrophoretic ultra-high-frequency characterization and in silico sorting on uptake of rare earth elements by Cupriavidus necator

Rare earth elements (REEs) are widely used across different industries due to their exceptional magnetic and electrical properties. In this work, Cupriavidus necator is characterized using dielectrophoretic ultra-high-frequency measurements, typically in MHz range to quantify the properties of cytoplasm in C. necator for its metal uptake/bioaccumulation capacity. Cupriavidus necator, a Gram-negative bacteria strain is exposed to REEs like europium, samarium, and neodymium in this study. Dielectrophoretic crossover frequency experiments were performed on the native C. necator species pre- and post-exposure to the REEs at MHz frequency range. The net conductivity of native C. necator, Cupriavidus europium, Cupriavidus samarium, and Cupriavidus neodymium are 15.95 ± 0.029 μS/cm, 16.15 ± 0.028 μS/cm, 16.05 ± 0.029 μS/cm, 15.61 ± 0.005 μS/cm respectively. The estimated properties of the membrane published by our group are used to develop a microfluidic sorter by modeling and simulation to separate REE absorbed C. necator from the unabsorbed native C. necator species using COMSOL Multiphysics commercial software package v5.5.     

Electrical conductance,density and viscosity of the system lead(II) dodecanoate/dodecanoic acid

Data are presented for the densities, electrical conductances and viscosities of the molten system lead(II) dodecanoate/dodecanoic acid. Over the concentration range studied, molar volumes are linear functions of concentration at any selected temperature, although there are indications of deviations from ideal behaviour over the complete composition range from pure soap to pure acid. The molar volumes of the system lead(II) carboxylate/carboxylic acid for the even chain acids C₁₀ to C₁₈ are linear functions of chain length. As with other lead(II) dodecanoate systems, the Arrhenius plots for the conductance of the mixtures show curvature.Activation energies for conductance in the low temperature region show a steady decrease with increasing mole fraction of the acid. It is suggested that this arises largely from the increased mobility of the Pb²⁺ ion. The activation energies for viscous flow in the mixtures are similar to that of pure lead dodecanoate. Studies of the viscosities of the system lead(II) carboxylate/carboxylic acid as a function of the temperature for the even chain length acids C₁₀ to C₁₈ suggest a slight decrease in size of the unit of viscous flow when acid is present.     

Perturbation Solution for One-Dimensional Flow to a Constant-Pressure Boundary in a Stress-Sensitive Reservoir

Transport in Porous Media - Most analyses of fluid flow in porous media are conducted under the assumption that the permeability is constant. In some “stress-sensitive” rock formations,...     

A regioselective 1,3‐dipolar cycloaddition of 2‐arylidene‐1‐tetralones with DPNI

Synthesis of a series of novel 1,3‐diphe nyl‐4‐arylspiropyrazolines[5.2¹]‐1¹‐tetralones has been accomplished in good yield by regioselective 1,3‐dipolar cycloaddition of diphenylnitrilimine with (E)‐2‐arylidene‐1‐tetralones. X‐ray crystal structure analysis of one of the products 4b confirms the structure and the regiochemistry of cycloaddition. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 331–336, 1999     

Anomalous temperature dependence of speed of sound of bulk poly(N-isopropylacrylamide) hydrogels near the phase transition

Bulk Poly(N-isopropylacrylamide) (PNIPAm) hydrogels are thermally responsive polymers that undergo a sharp volumetric phase transition around its lower critical solution temperature of 33 °C. The physical characteristics of bulk, micro-, and nano-form PNIPAm hydrogel have been well-studied, and have applications ranging from biomedical devices to mechanical actuators. An important physical characteristics which reveals lack of available information is speed of sound. Prior studies have utilized Brillouin scattering, multi-echo reflection ultrasound spectroscopy, the sing-around method, and others in measuring the speed of sound. We use a planar resonant cavity with bulk PNIPAm hydrogel in aqueous solution to determine the temperature dependent speed of sound around the lower critical solution temperature. The results show sharp nonmonotonic behavior of the sound velocity in vicinity of the phase transition.     

Elemental characterization of airborne particulates at two Nigerian locations during the Harmattan season

Airborne particulate matter collected during the Harmattan season at Kano in the northern part, and Ile-Ife in the southern part of Nigeria was analyzed for about 30 elements by a combination of instrumental neutron activation analysis and X-ray fluorescence analysis. Although the total suspended particulate concentration (ng/m³) is much higher in Kano than Ife, the elemental composition at both locations is very similar and cluster analysis shows a strong correlation between the two, indicating a common origin for particulates. Particle-size distribution studies show that Kano dust is mainly coarse while Ife dust is mainly fine. The crustal-type elements are mainly concentrated in the coarse particles (3 m) at both locations while the conventional anthropogenic elements are hosted mainly by the fine particles (0.49 m and below).     

Usefulness of nuclear and atomic-based analysis techniques in air pollution studies in Nigeria

Three nuclear and atomic-based techniques for elemental analysis of air-particulate samples are discussed in terms of their usefulness in an environmental monitoring and impact assessment programme, supported by the European Economic Community, in Nigeria. Instrumental neutron activation analysis (INAA) and proton induced X-ray emission (PIXE) analysis are compared with respect to the number of elements detected and the detection limits obtained for air-particulate matrices. The latter is used in conjunction with Rutherford backscattering spectrometry (RBS) in order to correct for variations in matrix composition. A scanning electron microprobe (SEM) with analytical facilities is also employed mainly for characterization of the air-particulates through measurement of particle size and morphology. The value of carrying out statistical analysis for differentiating between collection sites or sources of pollution is emphasised. Reference to results obtained from the analysis of air-particulates collected during the Harmattan season at Kano and Ife, separated by about 1000 km place the problem in context and serve to illustrate the requirements.     

Generalized Fourier transforms for the acoustic pressure and velocity in compressible dissipative stratified media

Generalized Fourier transforms are derived for the acoustic pressure and velocity in compressible dissipative plane stratified media. The acoustic source terms are accounted for in the equations of continuity and force. The acoustic pressure and velocity are each expressed as sums of two infinite (branch cut) integrals and a discrete term. In the far field the infinite integrals correspond to the direct and specularly reflected waves and the lateral wave. The discrete term associated with the pole of the reflection coefficient is the surface wave. The transforms provide a suitable basis for the expansion of the acoustic pressure and the velocity when the height of the interface, the adiabatic bulk modulus, the equilibrium density, and the absorption of the medium vary. Both exact boundary conditions and the approximate impedance boundary condition are considered in this work.     

Influence of atomic recoil on power broadened lineshapes in 2-level atoms

The power broadened absorption lineshapes of 2-level sodium atoms were carefully studied, using a frequency stabilized cw dye laser and a highly collimated atomic beam. At low driving fields the absorption lineshape was lorentzian as expected. However, at field intensities greater than 50 mW/cm², the lineshape exhibited an asymmetry which was attributed to atomic recoil effects.     

Electro‐osmotic surface effects generation in an electrokinetic‐based transport device: A comparison of RF and MW plasma generating sources

It is a common practice in insulator‐based dielectrophoretic separation to use and reuse PDMS‐constructed microdevice for an extended period of time while performing biological and technical replicate experiments. This is usually done to rule out any effects of device variation on separation efficiency. Ensuring that all experimental conditions remain the same is critical to the conclusion that can be drawn from such repeated experiments. One important contributing factor to the flow of materials within the device is electro‐osmotic velocity, which stems from the surface condition of the device construction materials. In this paper, we present an affordable microwave‐based (MESA‐Mgen) oxygen plasma cleaner developed for approximately less than $100 using readily obtainable parts from an average local hardware store with no specialized tools. This low‐cost room‐air microwave plasma generator was designed using an R‐4055, 400 W, 2450 MHz half‐pint household microwave oven (Sharp ® ) for exploring the possibility of sealing polydimethylsiloxane (PDMS) devices onto glass with minimal budgetary commitment. Microfluidic channels generated using MESA‐Mgen were evaluated for their electro‐osmotic velocities while factors including contact angles, storage‐solvent, half‐way hydrophobicity period were also explored with MESA‐Mgen, and the results were compared to those obtained from the commercially available plasma cleaner (COM‐PC). These outcomes revealed that the MESA‐Mgen induced hydrophilicity and ensured leak‐free sealing of PDMS substrates in a manner comparable with the COM‐PC.