Solvent Water Content as a Factor in the Design of Metal Ion Extraction Systems Employing Ionic Liquids

In the extraction of strontium nitrate from aqueous nitric acid solutions into a series of hydrophobic N-(1-hydroxyalkyl)-N’-alkylimidazolium bis[(trifluoromethyl)sulfonyl]imides by dicyclohexano-18-crown-6, a correlation has been demonstrated between the conditional extraction constant of strontium (K’_ex,Sr) and the concentration of water in the equilibrated ionic liquid (IL) phase. Despite the absence of a hydroxyl group on the IL cation, essentially the same relationship is observed for the analogous N,N’-dialkylimidazolium ILs. In both instances, the correlation is attributed to the coextraction of the hydrated nitrate ion and its solvation by the hydrated diluent. Transitions of water in the attenuated total reflectance-infrared spectra of the ILs are consistent with the existence of multiple states of water. The extraction efficiency for a given water content is greater for the ILs examined than for conventional solvents (i.e., n-alcohols). When coupled with existing knowledge of the factors influencing cation partitioning into ILs, these results provide insight into the IL structural characteristics required to effect efficient metal ion extraction from acidic media.     

Rare Cell Capture in Microfluidic Devices

This article reviews existing methods for the isolation, fractionation, or capture of rare cells in microfluidic devices. Rare cell capture devices face the challenge of maintaining the efficiency standard of traditional bulk separation methods such as flow cytometers and immunomagnetic separators while requiring very high purity of the target cell population, which is typically already at very low starting concentrations. Two major classifications of rare cell capture approaches are covered: (1) non-electrokinetic methods (e.g., immobilization via antibody or aptamer chemistry, size-based sorting, and sheath flow and streamline sorting) are discussed for applications using blood cells, cancer cells, and other mammalian cells, and (2) electrokinetic (primarily dielectrophoretic) methods using both electrode-based and insulative geometries are presented with a view towards pathogen detection, blood fractionation, and cancer cell isolation. The included methods were evaluated based on performance criteria including cell type modeled and used, number of steps/stages, cell viability, and enrichment, efficiency, and/or purity. Major areas for improvement are increasing viability and capture efficiency/purity of directly processed biological samples, as a majority of current studies only process spiked cell lines or pre-diluted/lysed samples. Despite these current challenges, multiple advances have been made in the development of devices for rare cell capture and the subsequent elucidation of new biological phenomena; this article serves to highlight this progress as well as the electrokinetic and non-electrokinetic methods that can potentially be combined to improve performance in future studies.     

The impact of multi-frequency and forced disturbances upon drop size distributions in prilling

The dynamics of curved liquid jets, such as those emanating from wall of a porous cylinder rotating about its vertical axis, are of interest to industries employing the prilling process to manufacture particulate products such as fertilisers. Although many theoretical and experimental studies have been published to date, none have addressed how mechanical vibrations affect the dynamics. In this paper, the influence of multiple disturbance frequencies upon the jet dynamics (imparted by mechanical vibrations), is examined for the first time. The theoretical predictions, obtained using both linear and non-linear models, show a much better agreement with results obtained from pilot-scale experiments than have been obtained in previous studies. The use of additional forced disturbances to control the particle size is also considered.     

Application of neural networks to detection of medical fraud

A multi-layer perceptron (MLP) network was trained to classify the practice profiles of a sample of medical general practitioners who had been classified by expert consultants into four classes ranging from having normal to having abnormal profiles. This method follows the two-class neural network classification of medical practice profiles developed at the Health Insurance Commission in 1990. A technique based on the probabilistic interpretation of the output of the neural network was used to see if it improved the performance of the MLP given the extent of noise (i.e. inconsistencies) in the experts' classifications. Kohonen's Self-Organising Map was also applied to analyse the consultants' classifications and it was found that an approach which combined the four classes into two was a more appropriate way to represent the classification data. The MLP network was then retrained using a two-class classification and a high agreement rate between the classifications of the MLP and the classifications of consultants was achieved.     

Hydrologic Characteristics of a 35-Year-Old Underground Mine Pool

The hydrology of a 14,672 acre (5,940 ha) coal mine complex in Cambria County, Pennsylvania, USA, was characterized. This flooded mine complex was evaluated to determine the potential of using the mine water for downstream agricultural purposes in an adjoining watershed. The hydrologic characteristics of the mine complex dictate the amounts and rates of mine water discharge that are available. The original coal extraction rate was known to be 63%, but post-mining subsidence has reduced the effective porosity to a mean of 11%. Thus, the mine stores considerably less mine water than was anticipated, a priori. The mine receives vertical recharge averaging 0.27 gallons (gal) per minute per acre (24.6 L/s per ha), which is equivalent to 11.6% of the mean precipitation. The recharge rate fluctuates about the mean by ±22%. The low storage capacity combined with the moderately low recharge rates allow the large mine complex to be rapidly drawn down when the pumping rate is raised from 4.68 to 9.36 × 10⁶ gal (17.7–35.4 × 10⁶ L/day). Conversely, the mine refills rapidly, up to 0.8 ft (0.24 m) or spatially 33 acres (13.4 ha) per day, once the pumping rate is reduced back to 4.68 × 10⁶ gal/day (17.7 × 10⁶ L/day), which is well below the total recharge rate. In addition to vertical recharge, 6.3–40.4% of the inflow into the mine pool complex occurs from coal barrier seepage from an adjacent flooded mine. The seepage rates are relatively constant and are estimated to be insensitive to changes in head up to 50 ft (15.2 m).     

Surface-relief fiber Bragg gratings for sensing applications

We present a new type of fiber Bragg grating (FBG) in which we etch the grating into the flat surface of a D-shaped optical fiber. Instead of being written in the core of the fiber, as are standard FBGs, these surface-relief FBGs are placed in the cladding above the core. These gratings are a viable alternative to standard FBGs for sensing applications. We describe the fabrication process for etching Bragg gratings into the surface of D-fibers and demonstrate their performance as temperature sensors.     

Synthesis and Biological Evaluation of (−) and (+)-Spiroleucettadine and Analogues

A second-generation enantiospecific synthesis of spiroleucettadine is described. The original reported antibacterial activity was not observed when the experiment was repeated on the synthetic samples; however, significant anti-proliferative activity was uncovered for both enantiomers of spiroleucettadine. Comparison of the optical rotational data and ORD-CD spectra of both enantiomers and the reported spectrum from the natural source have not provided a definitive answer regarding the absolute stereochemistry of naturally occurring spiroleucettadine. Efforts then focussed on alteration at the C-4 and C-5 positions of the slightly more active (−)-spiroleucettadine. Ten analogues were synthesised, with three analogues found to possess similar anti-proliferative profiles to spiroleucettadine against the H522 lung cancer cell line.     

Cladding Glass Development for Semiconductor Core Optical Fibers

Glass-clad optical fibers comprising a crystalline semiconductor core have garnered considerable recent attention for their potential utility as novel waveguides for applications in nonlinear optics, sensing, power delivery, and biomedicine. To date, cladding compositions have relied on commercially-available expedients and have not been tailored for the specific semiconductor core nor the application. In this work, more-optimum silicate and nonoxide glass compositions are developed for unary (Si, Ge), binary (InSb, GaAs), and ternary (GaAlSb) semiconductor cores based on two main design criteria: (1) matching the thermal expansion coefficient between semiconductor core and glass cladding and (2) matching the viscosity-temperature dependences such that the cladding glass draws into fiber at a temperature slightly above the melting point of the semiconductor. While this latter requirement is critical to the molten core fabrication method, which offers a practical approach to long fiber lengths at acceptable manufacturing speeds (>m/s), these compositions are more broadly applicable to other semiconductor fiber processing methods. Preliminary experimental results on silicon core optical fiber are provided and show a marked diminution in oxygen content relative to analogous fibers drawn using a pure silica cladding.     

In Grid Protection,New Technologies Can Threaten and Secure Utilities

The risks and security challenges that utilities must manage have increased substantially in recent decades.