VARIATIONS IN SALINITY STRUCTURE IN SASKATCHEWAN’S DEVONIAN CARBONATES

Industry provided and public domain geochemical and isotopic data from 1950 to present day were collected for the purpose of this research. The intent of this study is to better understand the groundwater flow patterns and hydrochemistry in Devonian carbonates within the Saskatchewan and Williston basins. The Birdbear, Duperow, Souris River, and Dawson Bay formations are of interest owing to their proximity to the mining units of the Prairie Evaporite Formation. Due to the undesirable outcomes of groundwater interacting with the soluble minerals of the mining unit, the understanding of the nature of the water contained in the overlying units is of great importance. The creation of a comprehensive database has allowed for graphical as well as spatial analysis of water chemistry data within the basin. In addition, it is now possible to assess for patterns of variation and to attempt to track chemical evolution at a regional scale through the manipulation of this data. By combining data on water chemistry, interpreting the salinity characteristics and expressing the results in a spatial context, information on mineral precipitation, dissolution, and fluid migration were obtained. Patterns found were then utilized to assess regional scale hydrogeology, recharge and discharge. Through a graphical and regional assessment of the stratigraphic hydrochemistry it has been shown that the four units differ. The Birdbear, Duperow, Souris River, and Dawson Bay formations were shown to comprise of an end member type system ranging from meteoric water dominated to original syndepositional evaporated sea water dominated chemistries. Ratios of Na to Cl and Br to Cl, TDS concentrations, as well as δD and δ18O isotope values of water samples have demonstrated Birdbear and Duperow formations have seen the greatest influence from meteoric water input and halite dissolution while the Dawson Bay Formation shows a signature indicative of syndepositional evaporated sea water. The Souris River Formation consists of a mixture of these two end-member hydrochemistries. At a regional scale, the four formations follow known trends in hydrogeology, with recharge indicated in in the south and south west sides of the basins, and discharge in the north and north east along the Manitoba escarpment. Concentrations of TDS also support the location of previously mapped large-scale evaporite dissolution features. It has been shown using TDS, Na/Cl, and δH2/δO18 that the signature of a water sample from a stratigraphic unit in the center of the basin can look identical to that of the signature of a different stratigraphy at the basin edge. Resultant variation in salinities, indicating the different sources of ground water as well as the evolution through various degrees of water rock interaction, has raised questions on the validity of attempting to use chemistry to stratigraphically fingerprint water samples. It has been shown groundwater salinity characteristics have a great degree of variability depending on the location in the basin. Therefore when attempting to use chemistry to determine which stratigraphic horizon a water sample comes from it is essential that both a thorough regional and local scale hydrochemical analysis are done

Low-frequency ultrasound to enhance topical drug delivery to the nail

The aim of this study was to investigate the potential of low-frequency ultrasound as a physical technique to enhance the ungual permeation of topically applied drugs

Confounding Issues in the Deadweight Loss of Gift-Giving

When a gift is given, someone other than the final consumer makes the consumption choice. Thus there is a possibility that the gift will not match the preferences of the receiver, i.e., the gift will represent a wise use of the money given the gift-giver's tastes but not necessarily a wise use of money given the recipient's tastes. In other words, gift giving can result in a deadweight loss. This paper addresses and clarifies the discrepancy between Waldfogel's (1993) finding of a deadweight loss from gift giving and Solnick and Hemenway's (1996) finding of a deadweight gain from gift giving. It also builds on some of the concerns raised by Ruffle and Tykocinski (2000).

Image-Based Investigation : Biorelevant Solubility of α and γ Indomethacin

Solubility is a physicochemical property highly dependent on the solid-state form of a compound. Thus, alteration of a compound’s solid-state form can be undertaken to enhance the solubility of poorly soluble drug compounds. In the Biopharmaceutics Classification System (BCS), drugs are classified on the basis of their aqueous solubility and permeability. However, aqueous solubility does not always correlate best with in vivo solubility and consequently bioavailability. Therefore, the use of biorelevant media is a more suitable approach for mimicking in vivo conditions. Here, assessed with a novel image-based single-particle-analysis (SPA) method, we report a constant ratio of solubility increase of 3.3 ± 0.5 between the α and γ solid-state forms of indomethacin in biorelevant media. The ratio was independent of pH, ionic strength, and surfactant concentration, which all change as the drug passes through the gastrointestinal tract. On the basis of the solubility ratio, a free-energy difference between the two polymorphic forms of 2.9 kJ/mol was estimated. Lastly, the use of the SPA approach to assess solubility has proven to be simple, fast, and both solvent- and sample-sparing, making it an attractive tool for drug development.Peer reviewe

Characterisation of an in Vitro Aged Cell Culture Model

The present study aims to provide a detailed protocol to obtain an aged cell culture model, which is conveniently characterised in terms of morphology, metabolism, and key biochemical markers of senescence. Commercial Human Dermal Fibroblasts (HDF) (67-year-old female Asian donor) were cultured over a span of 35 passages to determine at what passages they express the phenotypes found in vivo in the geriatric population. The growth rate and density (counting, Trypan Blue) at confluence declined 4- and 3-fold, respectively. During 15 passages in vitro ageing the fibroblast metabolic capacity (XTT) was heavily reduced (by 75%), while conversely the content of cellular proteins (SRB) slightly increased (2 fold). Senescent cells (SA-β-gal positive) were continuously emerging from 0 to 20%. Freezing/thawing at this stage restored metabolic performance to original values which declined at a similar rate as before. Passages 5 - 10 of our selected aged HDFs were found to mimic in vivo tissue of older adults to the greatest extent

Sustained release of antimicrobials from double-layer nanofiber mats for local treatment of periodontal disease, evaluated using a new micro flow-through apparatus

Periodontal disease is a widespread chronic condition associated with degradation of periodontal tissues that requires more effective approaches for its treatment. Thus, the aim was to develop a nanodelivery system for local application of antimicrobials, with evaluation in vitro using a newly developed micro flow-through apparatus that simulates local in-vivo conditions in the periodontal pocket: small resting volume, and low gingival crevicular fluid flow rate. We successfully developed a double-layer nanofiber mat composed of a chitosan/ poly(ethylene) oxide nanofiber layer with 30% ciprofloxacin, and a poly(ε-caprolactone) nanofiber layer with 5% metronidazole. The precisely designed composition enabled sustained in-vitro release of the antimicrobials according to their specific drug release mechanisms. The rate-limiting step of ciprofloxacin release was its own low solubility at pH 7.4, when there was excess of solid drug present in the delivery system. In contrast, sustained release of metronidazole was due to slow penetration of dissolution medium through the hydrophobic poly(ε-caprolactone) nanofiber layer. The double-layer nanofiber mat developed showed antibacterial activity against Escherichia coli and Aggregatibacter actinomycetemcomitans based on plate antibiogram assays. The antimicrobial concentrations released from the nanofiber mats determined using the developed apparatus were above the minimal inhibitory concentrations against the periodontal pathogens for up to 7 days, which is valuable information for prediction of the efficacy of the nanodelivery system. Although this apparatus was specifically designed for characterization of formulations associated with treatments for periodontal disease, its applicability is much wide, as for development of any delivery system for application at target sites that have similar local conditions

Properties, Engineering and Applications of PolymericNanofibers: Current Research and Future Advances

The subject of nanomedicine has seen a surge in research activity over the past decade, with nanofibers being a particularly active field. Nanofibers are solid, dry fibers with nanometer diameters, made of various polymers, whereas electrospinning is a versatile, simple, elegant, reproducible, continuous and scalable technology for their preparation. Nanofibers are a unique class of materials in the biomedical field, since they provide a biomimetic environment on the nanometer scale, a three-dimensional architecture with the desired surface properties on the micrometer scale, combined with mechanical strength and physiological acceptability on the macro scale. In particular, their ability to imitate the fibrillar elements of a natural extracellular matrix in a very realistic way is crucial. In this paper we introduce the fundamental aspects of the electrospinning process and the properties of nanofibers, as well as highlighting the enormous potential of nanofibers as drug-delivery systems and tissue scaffolds

Rhombohedral magnetostriction in dilute iron (Co) alloys

Iron is a well-utilized material in structural and magnetic applications. This does not mean, however, that it is well understood, especially in the field of magnetostriction. In particular, the rhombohedral magnetostriction of iron, λ111 , is anomalous in two respects: it is negative in sign, in disagreement with the prediction of first principles theory, and its magnitude decreases with increasing temperature much too rapidly to be explained by a power law dependence on magnetization. These behaviors could arise from the location of the Fermi level, which leaves a small region of the majority 3d t2g states unfilled, possibly favoring small internal displacements that split these states. If this view is correct, adding small amounts of Co to Fe fills some of these states, and the value of λ111 should increase toward a positive value, as predicted for perfect bcc Fe. We have measured the magnetostriction coefficients (λ111 and λ100) of pure Fe, Fe97Co3, and Fe94Co6 single crystals from 77 K to 450 K. Resonant ultrasound spectroscopy has been used to check for anomalies in the associated elastic constants, c 44 and c′. The additional electrons provided by the cobalt atoms indeed produced positive contributions to bothmagnetostriction constants, λ111 and λ100, exhibiting an increase of 2.8 × 10−6 per at. % Co for λ111 and 3.8 × 10−6 per at. % Co for λ100