A prototype personal aerosol sampler based on electrostatic precipitation and electrowetting-on-dielectric actuation of droplets

This is an Open Access article, distributed under the terms of the Open Government Licence. http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/ Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved. The version of record (T. G. Foat, et al, 'A prototype personal aerosol sampler based on electrostatic precipitation and electrowetting-on-dielectric actuation of droplets', Journal of Aerosol Science, Vol. 95, pp. 43-53, May 2016) is available online at doi: https://doi.org/10.1016/j.jaerosci.2016.01.007.An electrostatic precipitator (ESP) based personal sampler with a laboratory based electrowetting-on-dielectric (EWOD) concentrator could provide a high concentration rate personal aerosol sampler system. A prototype system has been developed based on the concept of a lightweight personal ESP collecting aerosol particles onto a hydrophobic surface followed by the use of an EWOD actuated droplet system to transfer the deposited sample into a microlitre size water droplet.A personal sampler system could provide military or civilian personnel with a wide area biological monitoring capability supplying information on who has been infected, what they have been infected with, how much material they were exposed to and possibly where and when they were infected. Current commercial-off-the-shelf (COTS) personal sampler solutions can be bulky and use volumes of water to extract the sample that are typically a thousand times greater than the proposed method.Testing of the prototype ESP at a sample flow rate of 5Lmin-1 demonstrated collection efficiencies greater than 80% for sodium fluorescein particles larger than 4μm diameter and of approximately 50% at 1.5μm. The ESP-EWOD system collection efficiency measured for Bacillus atrophaeus (BG) spores with an air sample flow rate of 20L min-1 was 2.7% with a concentration rate of 1.9×105 min-1. This was lower than expected due to the corona ions from the ESP affecting the hydrophobicity of the collection surface and hence the EWOD efficiency. However, even with this low efficiency the concentration rate is more than an order of magnitude higher than the theoretical maximum of the best current COTS personal sampler. For an optimised system, ESP-EWOD system efficiency should be higher than 32% with a comparable increase in concentration rate.Peer reviewe

Comparison of Six Artificial Diets for Western Corn Rootworm Bioassays and Rearing

The western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is considered the most important maize (Zea mays L.) pest in the U.S. Corn Belt. Bioassays testing susceptibility to Bacillus thuringiensis Berliner (Bt) and other toxins of corn rootworm larvae often rely on artificial diet formulations. Successful bioassays on artificial diet for corn rootworm have sometimes been challenging because of microbial contamination. Toward the long-term goal of developing a universal artificial diet for western corn rootworm larvae, we compared larval survival, dry weight, and percentage of molt in 10-d bioassays from six current diets of which we were aware. In addition, as part of longer term rearing efforts, we recorded molting over an extended period of development (60 d). Six different artificial diets, including four proprietary industry diets (A, B, C, and D), the first published artificial diet for western corn rootworm (Pleau), and a new diet (WCRMO-1) were evaluated. Western corn rootworm larval survival was above 90% and contamination was 0% on all diets for 10 d. Diet D resulted in the greatest dry weight and percentage molting when compared with the other diets. Although fourth-instar western corn rootworm larvae have not been documented previously (only three instars have been previously documented), as many as 10% of the larvae from Diet B molted into a fourth instar prior to pupating. Overall, significant differences were found among artificial diets currently used to screen western corn rootworm. In order for data from differing toxins to be compared, a single, reliable and high-quality western corn rootworm artificial diet should eventually be chosen by industry, academia, and the public as a standard for bioassays

Susceptibility of northern corn rootworm (\u3ci\u3eDiabrotica barberi\u3c/i\u3e) populations to Cry3Bb1 and Gpp34/Tpp35Ab1 proteins in seedling and diet overlay toxicity assays

The northern corn rootworm, Diabrotica barberi Smith & Lawrence (Coleoptera: Chrysomelidae) is a major pest of maize in the United States Corn Belt. Recently, resistance to Bacillus thuringiensis (Bt) maize was reported in North Dakota and increased use of Bt maize hybrids could facilitate resistance evolution in other maizeproducing states. In this study, susceptibility to Bt proteins was evaluated in wild D. barberi populations from 8 fields collected in 5 different states (Minnesota, Missouri, Nebraska, Iowa, and North Dakota). Field populations were compared to a susceptible D. barberi colony in seedling and diet toxicity assays conducted with 3 concentrations of Cry3Bb1 (0.4, 4.0, and 40.0 μg/cm2) and Gpp34/Tpp35Ab1 (previously called Cry34/35Ab1; 1.4, 14.0, and 140.0 μg/cm2). The 2019 population from Meeker Co., Minnesota (MN-2019), exhibited the lowest mortality to Cry3Bb1 and also had nominally lowest mortality to Gpp34/Tpp35Ab1 at the highest concentrations tested in diet toxicity assays. Percent second instar was also highest for larvae of the Minnesota population surviving Cry3Bb1. In seedling assays, MN and IA-2018 populations exhibited the highest proportion survival and dry weight to both proteins expressed in corn. No significant differences in mortality, percent second instar, and dry weight were observed at the highest concentration for both proteins among the populations collected in in 2020. Most D. barberi populations were still highly susceptible to Cry3Bb1 and Gpp34/Tpp35Ab1 proteins based on diet and seedling assays, but resistance appears to be developing in some D. barberi populations. Now that methods are available, resistance monitoring may also be needed for D. barberi in some regions

Natural Distribution of Parasitoids of Larvae of the Fall Armyworm, Spodoptera frugiperda, in Argentina

To develop a better understanding of the natural distribution of the fall armyworm, Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae), and to update the knowledge of the incidence of its complex of parasitoids. S. frugiperda, samplings in whorl-stage corn were carried out in provinces of Argentina from 1999 to 2003. S. frugiperda larvae were collected from corn in localities of the provinces of Tucumán, Salta, Jujuy, Santiago del Estero, La Rioja, Córdoba, San Luis, Chaco and Misiones. In each locality 30 corn plants were sampled and only larvae located in those plants were collected. The parasitoids that emerged from S. frugiperda larvae were identified and counted. The abundance of the parasitoids and the parasitism rate were estimated. The S. frugiperda parasitoids collected were Campoletis grioti (Blanchard) (Hymenoptera: Ichneumonidae), Chelonus insularis (Cresson) (Hymenoptera: Braconidae), Archytas marmoratus (Townsend) (Diptera Tachinidae) and/or A. incertus (Macquart), Ophion sp. (Hymenoptera: Ichneumonidae), Euplectrus platyhypenae Howard (Hymenoptera: Eulophidae), and Incamyia chilensis (Aldrich) (Diptera Tachinidae). C. grioti was the most abundant and frequent during the five-year survey. Similar diversity of parasitoids was obtained in all the provinces, with the exception of I. chilensis and E. platyhypenae that were recovered only in the province of Salta. In the Northwestern region, in Tucumán, C. grioti and species of Archytas were the most abundant and frequent parasitoids. On the contrary, in Salta and Jujuy Ch. insularis was the parasitoid most abundant and frequently recovered. The parasitism rate obtained in Tucumán, Salta and Jujuy provinces were 21.96%, 17.87% and 6.63% respectively with an average of 18.93%. These results demonstrate that hymenopteran and dipteran parasitoids of S. frugiperda occurred differentially throughout the Argentinian provinces and played an important role on the natural control of the S. frugiperda larval population

The epidemiology of enterococci

The enterococci are emerging as a significant cause of nosocomial infections, accounting for approximately 10 % of hospital acquired infections. They are found as normal inhabitants of the human gastrointestinal tract, but may also colonize the oropharynx, vagina, perineal region and soft tissue wounds of asymtomatic patients. Until recently, evidence indicated that most enterococcal infections arose from patients' own endogenous flora. Recent studies, however, suggest that exogeneous acquisition may occur and that person-to-person spread, probably on the hands of medical personnel, may be a significant mode of transmission of resistant enterococci within the hospital. The use of broad-spectrum antibiotics, especially cephalosporins, is another major factor in the increasing incidence of enterococcal infections. These findings suggest that barrier precautions, as applied with other resistant nosocomial pathogens, along with more judicial use of antibiotics may be beneficial in preventing nosocomial spread of resistant enterococci.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47899/1/10096_2005_Article_BF01963631.pd