Extraction of phenolic compounds from fresh leaves: A comparison of methods

The conventional sonicator/shaker bath method for phenolic extraction was compared with a less traditional one using a homogenizer. The homogenizer proved to be both more efficient and consistent in extracting phenolics from tender, as well as tough, leaves. We propose that adoption of the homogenizer technique will increase phenolic yield and efficiency.     

LOCATING THE CAMERA IN A DIGITAL TIME

This paper provides a practice-led exploration of various photographic periods, processes and camera media and their changing placement within a data-driven society and the wider context of how these media can be more closely considered in regard to their sustainable nature. The paper argues that making associations between the different photographic contexts of analogue and digital should become a default process for practitioners, including the understanding of the resource differences between them and their implications on the environment.     

In vitro model improves the prediction of soil arsenic bioavailability: worst-case scenario

There is a strong interest in developing an in vitro arsenic (As) model that satisfactorily estimates the variability in in vivo relative oral bioavailability (RBA) measurements. Several in vitro tests have been developed, but none is universally accepted due to their limited success in predicting soil As RBA. A suite of amorphous and crystalline solid As phases were chosen, utilizing a worst-case scenario (WCS) that simulated fasting children's gastric solution chemistry. The objectives of this study were to (i) determine the effects of residence time, pH, and solid-to-solution ratio on As bioaccessibility and speciation in the in vitro gastric test; (ii) provide the fundamental basis for an optimized in vitro model constrained by the WCS; and (iii) validate the optimized in vitro test with the in vivo RBA obtained with BALB/c mice. The gastric pH was the only significant (p < 0.05) factor influencing solid As bioaccessibility. Bioaccessible As retained the oxidation state after its release from the solid into the gastric solution. The optimized in vitro model adequately predicted RBA values for a suite of solid As phases typically encountered in soils, with the exception of aluminum-based solids. This study is an excellent starting point for developing an in vitro test applicable to different As-contaminated soils.     

Cured polyesters based upon bisacid A2: Water absorption,toluene resistance,and resistance to 5% aqueous HNO3 and NaOH

Earlier papers have described the preparation and purification of bisacid A2,^1,2 the preparation and cure of crosslinkable polyesters,³ the thermal properties of cast sheet,⁴ and the mechanical properties of glass fiber laminates⁵ which were made from reactants that included bisacid A2 in two series of cocondensates. The present paper details the water absorption and the long-term effects (up to 12 months) of toluene, 5% aq. HNO₃, and 5% aq. NaOH. The effects of the last two were found to be negligible, but the water absorption and the toluene resistance appeared to be capable of correlation with the known composition and the inferred structure of the copolyesters.     

Stiffness alterations of single cells induced by UV in the presence of nanoTiO2

Nanocrystalline titanium dioxide (nanoTiO2) has been reported to generate reactive oxygen species (ROS) under UV illumination. In our studies, changes in mechanical properties of human skin fibroblasts, exposed to the oxidative stress induced in the presence of nanoTiO2 and UV light, were studied using atomic force microscopy (AFM). The exposure of cells to the action of ROS was performed at low TiO2 concentration (4 microg/mL) and under illumination with low-intensity UVA (8 and 20 mW/cm2) or UVC (0.1 mW/ cm2). AFM measurements of the cell stiffness were carried out immediately after exposure of cells to the oxidative stress. The data suggest that under illumination with low-intensity UVA nanoTiO2 generates ROS, which, in turn, damage cellular and subcellular structures. This process was detected by AFM as a marked drop in the cellular stiffness of ca. 30-75%, which occurred rapidly, in the time frame of 1 min. The photo-oxidative stress inducing the decrease of cell stiffness was cancelled in the presence of a well-established antioxidant, beta-carotene. The results highlight the sensitivity of AFM to detect early changes in mechanical properties of cells exposed to oxidative stress.     

Phenotypic and genetic characterization of antimicrobial resistance in Salmonella serovars isolated from retail meats in Alberta, Canada

This study determined the prevalence of Salmonella serovars, antimicrobial resistance (AMR) and resistance genes in Salmonella isolated from retail meats purchased in Alberta, Canada. Samples were collected during one year period (May 2007–April 2008) on weekly basis from 19 census divisions in Alberta. A total of 564 samples including chicken (n = 206), turkey (n = 91), beef (n = 134) and pork (n = 133) were purchased. Salmonella were recovered from chicken (40%), turkey (27%) and pork (2%) samples and was not found in ground beef. A total of 21, 8, and 3 different serovars were recovered from chicken, turkey and pork meats, respectively. Salmonella Hadar was most common in chicken whereas S. Heidelberg was common in turkey meat. Overall 29% (32/110) of isolates were susceptible to tested antimicrobials and resistance to ciprofloxacin, amikacin and nalidixic acid was not found in any isolate. Multiresistance (≥2 antimicrobials) was found in 56% of isolates. Resistance to amoxicillin–clavulanic acid (AMC), ceftiofur (TIO), and ceftriaxone (CRO) was found in about 21% of chicken and 25% of turkey isolates. Resistance to either of tetracycline (TET), streptomycin (STR) or ampicillin (AMP) was unconditionally associated with S. Hadar but resistance to either of TET, AMP, AMC, TIO, CRO or cefoxitin was associated with S. Heidelberg. The strA/B (42% isolates), tet(A) (28% isolates), bla_CMY-2 (21% isolates) and bla_TEM (17% isolates) were the most common resistance genes found. The bla_CMY-2 and bla_TEM genes were unconditionally associated with S. Heidelberg; tet(A) and strA/B with S. Hadar and tet(B) gene with S. Kentucky. The strA/B genes were not associated with S. Heidelberg. Our data suggests that the prevalence of Salmonella serovars varied by the meat type and that AMR and resistance genes varied by the Salmonella serovars.     

N-acryloxysuccinimide: Synthesis, characterization, and incorporation in dental adhesives

In an attempt to enrich the world of dentistry through the development of new materials, this study proposes to synthesize and incorporate a monomer containing the N-hydroxysuccinimide (NHS) ester reactive group to a dental adhesive. As such, this study developed a simple method to obtain NHS esters by employing acrylic acid (AA) and NHS in the presence of EDC (N-ethyl-N′-(3-dimethylaminopropyl)carbodiimide), from an aprotic medium. The experimental N-acryloxysuccinimide (NSA) monomer was analyzed by infrared spectroscopy (FTIR) and nuclear magnetic resonance of hydrogen (¹H NMR). This monomer was then incorporated within a prepared dental adhesive, in a 5% proportion. The modified adhesive, containing NSA, was applied to the dental surface of bovine teeth to obtain an adhesive/dentin interface in vitro. The characterization of this interface by Raman spectroscopy presented the formation of new amide bonds. Moreover, through scanning electron microscopy (SEM), it became possible to observe an intense penetration of this modified adhesive on the dental surface. Considering the outcome, it can be concluded that the synthesized NSA monomer provided a favorable condition for the dental adhesives to interact chemically with the dentin collagen fibers.