Characterization of Listeria monocytogenes isolates from lactating dairy cows in a Wisconsin farm: Antibiotic resistance,mammalian cell infection,and effects on the fecal microbiota

Listeria monocytogenes is an invasive foodborne pathogen that is ubiquitously present in the dairy farm environment. Although cattle are a reservoir of L. monocytogenes, most adult animals do not exhibit clinical symptoms, suggesting a homeostasis between this pathogen and the bovine gastrointestinal ecosystem. Nevertheless, substantial prevalence of L. monocytogenes fecal shedding by dairy cattle has been reported in many studies, posing threats of transmission within the herd and contamination of the human food supply. Accordingly, understanding the L. monocytogenes ecology within the bovine gastrointestinal tract is important to prevent clinical illness in the animal host, reduce transmission, and guide intervention strategies. In this study, we conducted a longitudinal sampling of fecal samples from 20 lactating dairy cows in one Wisconsin farm over a 29-d period and found a strikingly high incidence of L. monocytogenes shedding, in 90% of sampled animals. The L. monocytogenes isolates were genetically diverse, representing all common serotypes previously identified from cattle. Additionally, most tested isolates were resistant to ampicillin, and a few were also resistant to gentamicin or trimethoprim/sulfamethoxazole. Most isolates effectively infected human epithelial cells (Caco-2) and murine fibroblasts (L2), suggesting that they are all capable of causing systemic infection if the intestinal barrier is breached. Finally, we investigated the effects of L. monocytogenes colonization on the gastrointestinal tract microbiota by analyzing the fecal bacterial communities of some shedding and nonshedding cows. Whereas L. monocytogenes did not affect the α and β diversity of tested animals, a subset of shedding cows exhibited different abundances of certain operational taxonomic units within the Bacteroidetes and Firmicutes phyla compared with nonshedding cows. Overall, our findings highlight the threat of antibiotic resistance among some L. monocytogenes isolates, emphasize the need for a strain-specific approach in listeriosis treatment, and suggest the potential negative influence of subclinical L. monocytogenes carriage on animal gut health.     

Galactosyl oligosaccharide purification by ethanol precipitation

Galactosyl oligosaccharides (GOS) are prebiotics commonly manufactured by β-galactosidase conversion of lactose, producing a mixture containing GOS, lactose, glucose and galactose. Enrichment of GOS in this mixture adds value to the product. This study aimed to determine whether the addition of ethanol to aqueous saccharide solutions could be used to selectively precipitate and enrich GOS from a reaction mixture. High concentrations of ethanol (>70% v/v) were required to induce precipitation. The total saccharide concentration was a significant variable, with higher GOS enrichment occurring at lower total saccharide concentrations. Varying the temperature between 10 and 40 °C had less impact than had changes in the concentration of saccharide or ethanol. GOS was enriched 2.3 (±0.1) fold in the precipitate formed in a solution of 90% (v/v) ethanol with 28 g/L of total saccharide at 40 °C. Performing two such precipitations sequentially reduced the monosaccharides from 48% (w/w) of the total saccharides to 4% (w/w). GOS precipitation has potential for industrial application as it is simple in operation and offers levels of purification similar to those by other techniques.     

Development and evaluation of a magnesium–zinc–strontium alloy for biomedical applications — Alloy processing,microstructure, mechanical properties,and biodegradation

A new biodegradable magnesium–zinc–strontium (Mg–Zn–Sr) alloy was developed and studied for medical implant applications. This first study investigated the alloy processing (casting, rolling, and heat treatment), microstructures, mechanical properties, and degradation properties in simulated body fluid (SBF). Aging treatment of the ZSr41 alloy at 175 °C for 8 h improved the mechanical properties when compared to those of the as-cast alloy. Specifically, the aged ZSr41 alloy had an ultimate tensile strength of 270 MPa, Vickers hardness of 71.5 HV, and elongation at failure of 12.8%. The mechanical properties of the ZSr41 alloy were superior as compared with those of pure magnesium and met the requirements for load-bearing medical implants. Furthermore, the immersion of the ZSr41 alloy in SBF showed a degradation mode that progressed cyclically, alternating between pitting and localized corrosion. The steady-state average degradation rate of the aged ZSr41 alloy in SBF was 0.96 g/(m²·hr), while the pH of SBF immersion solution increased. The corrosion current density of the ZSr41 alloy in SBF solution was 0.41 mA/mm², which was much lower than 1.67 mA/mm² for pure Mg under the same conditions. In summary, compared to pure Mg, the mechanical properties of the new ZSr41 alloy improved while the degradation rate decreased due to the addition of Zn and Sr alloying elements and specific processing conditions. The superior mechanical properties and corrosion resistance of the new ZSr41 alloy make it a promising alloy for next-generation implant applications.     

The effect of nanowire length and diameter on the properties of transparent, conducting nanowire films

This article describes how the dimensions of nanowires affect the transmittance and sheet resistance of a random nanowire network. Silver nanowires with independently controlled lengths and diameters were synthesized with a gram-scale polyol synthesis by controlling the reaction temperature and time. Characterization of films composed of nanowires of different lengths but the same diameter enabled the quantification of the effect of length on the conductance and transmittance of silver nanowire films. Finite-difference time-domain calculations were used to determine the effect of nanowire diameter, overlap, and hole size on the transmittance of a nanowire network. For individual nanowires with diameters greater than 50 nm, increasing diameter increases the electrical conductance to optical extinction ratio, but the opposite is true for nanowires with diameters less than this size. Calculations and experimental data show that for a random network of nanowires, decreasing nanowire diameter increases the number density of nanowires at a given transmittance, leading to improved connectivity and conductivity at high transmittance (>90%). This information will facilitate the design of transparent, conducting nanowire films for flexible displays, organic light emitting diodes and thin-film solar cells.     

The historical geographies of growing and fermenting the Delaware grape in the Kōfu Basin of Yamanashi Prefecture,Japan

The Kōfu Basin in Yamanashi Prefecture is at the center of table grape and wine production in Japan. This article traces the historical geographies of the growing and fermentation of Delaware grapes in this region. Data were gathered from over 145 interviews with stakeholders across the table grape and wine industries, extensive archival research and participant observation as a grape farmer in the Kōfu Basin for over one and a half years. Emphasis is placed on intertwining that history to overarching developments in local viticulture and winemaking. This includes tracing the arrival of the cultivar from the USA to Japan at the start of the Meiji Restoration in 1868, early fermentation and later rapid diffusion linked to its popularity as the first commercially available seedless cultivar. Delaware reached the pinnacle of its popularity as a grape for the table and wine in the 1960s and 1970s, before changes in consumer demands to higher value table grapes and away from sweet wines led to its fairly rapid decline. Although significantly less Delaware is grown or fermented today, this introduced grape was and surprisingly continues to be highly influential on the developmental trajectories of Japanese grape growing and winemaking.     

Device characteristics of a 10.1% hydrazine‐processed Cu2ZnSn(Se,S)4 solar cell

A power conversion efficiency record of 10.1% was achieved for kesterite absorbers, using a Cu₂ZnSn(Se,S)₄ thin‐film solar cell made by hydrazine‐based solution processing. Key device characteristics were compiled, including light/dark J–V, quantum efficiency, temperature dependence of V_oc and series resistance, photoluminescence, and capacitance spectroscopy, providing important insight into how the devices compare with high‐performance Cu(In,Ga)Se₂. The record kesterite device was shown to be primarily limited by interface recombination, minority carrier lifetime, and series resistance. The new level of device performance points to the significant promise of the kesterites as an emerging and commercially interesting thin‐film technology. Copyright © 2011 John Wiley & Sons, Ltd.     

Improving myoelectric pattern recognition robustness to electrode shift by changing interelectrode distance and electrode configuration

Pattern recognition of myoelectric signals for prosthesis control has been extensively studied in research settings and is close to clinical implementation. These systems are capable of intuitively controlling the next generation of dexterous prosthetic hands. However, pattern recognition systems perform poorly in the presence of electrode shift, defined as movement of surface electrodes with respect to the underlying muscles. This paper focused on investigating the optimal interelectrode distance, channel configuration, and electromyography feature sets for myoelectric pattern recognition in the presence of electrode shift. Increasing interelectrode distance from 2 to 4 cm improved pattern recognition system performance in terms of classification error and controllability (p < 0.01). Additionally, for a constant number of channels, an electrode configuration that included electrodes oriented both longitudinally and perpendicularly with respect to muscle fibers improved robustness in the presence of electrode shift (p < 0.05). We investigated the effect of the number of recording channels with and without electrode shift and found that four to six channels were sufficient for pattern recognition control. Finally, we investigated different feature sets for pattern recognition control using a linear discriminant analysis classifier and found that an autoregressive set significantly (p < 0.01) reduced sensitivity to electrode shift compared to a traditional time-domain feature set.