320 research outputs found
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Trap Crop Systems for Striped Cucumber Beetle Control in Winter Squash
ABSTRACT CHAPTER 1
Striped cucumber beetle, Acalymma vittatum F., is the primary insect pest of cucurbit crops in the Northeastern United States. Adult beetles colonize squash crops from field borders, causing feeding damage at the seedling stage and transmitting the bacteria Erwinia tracheiphila Hauben et al. Conventional control methods rely on insecticide applications to the entire field, but surrounding main crops with a more attractive perimeter could reduce reliance on insecticides. Acalymma vittatum demonstrates a marked preference for Blue Hubbard squash (Cucurbita maxima Duchesne) over butternut squash (C. moschata Duchesne). Given this preference, Blue Hubbard squash has the potential to be an effective perimeter trap crop. We evaluated this system in commercial butternut fields in 2003 and 2004, comparing fields using perimeter trap cropping with Blue Hubbard to conventionally managed fields. In 2003 we used a foliar insecticide to control beetles in the trap crop borders, and in 2004 we compared systemic and foliar insecticide treatments for the trap crop borders. We found that using a trap crop system reduced or eliminated the need to spray the main crop area, reducing insecticide use by up to 94% compared to conventional control methods, with no increase in herbivory or beetle numbers. We also surveyed the growers who participated in these experiments and found a high level of satisfaction with the effectiveness and simplicity of the system. These results suggest that this method of pest control is both effective and simple enough in its implementation to have high potential for adoption amongst growers.
ABSTRACT CHAPTER 2
Winter squash is a vital agricultural commodity in many parts of the world. In the Northeastern United States, the primary insect pest of these crops is the striped cucumber beetle, Acalymma vittatum F, which has traditionally been controlled with multiple full field pesticide applications. Recent studies have indicated that using a Blue Hubbard squash perimeter trap crop system (PTC hereafter) can reduce insecticide use by \u3e90% in butternut squash, the primary winter squash grown in this region. This method involves dedicating a portion of the field to the trap crop. Despite the savings in insecticide costs, growers may be reluctant to give up field space for Blue Hubbard squash, which has a limited market. Finding a more marketable trap crop than Blue Hubbard would lower the barrier for adoption of this system. We tested eight varieties of three species of cucurbits for attractiveness to beetles relative to Blue Hubbard and butternut squash, and chose buttercup squash as the most promising replacement for Blue Hubbard. We compared the effect of a buttercup border, Blue Hubbard border, or control (no border) on beetle numbers, herbivory, and insecticide use. We found that buttercup squash performed equally well as Blue Hubbard as a trap crop, with up to 97% reduction in the total field area requiring insecticide compared to control fields. This study confirms the effectiveness of PTC systems and offers growers a more marketable trap crop
A 50 year old with a rapid neuropsychiatric deterioration and choreaform movements
A 50-year-old man presented acutely to the hospital with behavioural disturbance, choreiform movements and profound nihilistic delusions. He reported recent drug and alcohol abuse, and also apparent involvement in several recent criminal activities, for which he felt he should be punished. He arrived alone at the hospital after a concerned neighbour had called an ambulance. His initial level of agitation prevented formal cognitive testing. However, he was alert, verbally responsive and could obey commands. He was afebrile with normal observations and normal plasma glucose. Although his examination was challenging, the only abnormal neurological findings were bilateral choreiform upper limb movements
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Advanced Lithium Ion Battery Materials Prepared with Atomic Layer Deposition
As the world consumes the dwindling supply of fossil fuels, an alternative to gasoline powered vehicles will become necessary. Lithium ion batteries (LIBs) are emerging as the dominant power source for portable electronics, and are seen as a promising energy source in the development of electric vehicles. Current LIB technology is not well suited for vehicles, increases in the energy density, power density and durability are needed before LIB are ready for widespread use in electric vehicles. LiCoO2 and graphite are the dominant cathode and anode active materials, respectively in LIBs. On the cathode side, instabilities in LiCoO2 can lead to the deterioration of the LIB. Decomposition of electrolyte on the graphite anode surface to form a solid-electrolyte interphase (SEI) consumes lithium from the cathode resulting in a lower battery capacity. Instabilities in the in the SEI can result in catastrophic battery failure. Previous studies have employed metal oxides films, typically grown with wet chemical techniques, to stabilize LiCoO2 and mitigate the formation of the SEI on graphite. The thicknesses of films grown with wet chemical techniques was typically ∼50-1000 Å. In order to achieve higher power densities, the particle size of LIB active materials is being scaled down. As active materials get smaller the mass contribution of a protective film can become a significant fraction of the total mass. Atomic layer deposition (ALD) has been used to grow ultra thin films of Al2O3 on LiCoO2 and graphite. By altering the interaction between the active material and the battery electrolyte it was possible to improve the stability of both LiCoO2 and graphite electrodes in LIBs. In the case of graphite, the Al2O3 film may be thought of as an artificial SEI. During the initial charge-discharge cycle of a LIB, the electrolyte decomposes on the anode to form the SEI. The formation of the SEI is believed to prevent further decomposition of the electrolyte on the anode surface. The SEI contains electrolyte decomposition products including Li2CO3, Li2O, LiOH, LiF and R-OLi. In order to grow a truly artificial SEI on the graphite anode, i.e. grow a film that mimics the SEI that forms during charge-discharge cycling, new ALD chemistries for the growth of Li2CO3 and LiOH have been developed. The ALD of an artificial SEI layer may limit lithium loss and improve the capacity stability during charge-discharge cycles
The Sleipner storage site:Capillary flow modeling of a layered CO2 plume requires fractured shale barriers within the Utsira Formation
AbstractTo prevent ocean acidification and mitigate greenhouse gas emissions, it is necessary to capture and store carbon dioxide. The Sleipner storage site, offshore Norway, is the world's first and largest engineered waste repository for a greenhouse gas. CO2 is separated from the Sleipner gas condensate field and stored in the pore space of the Utsira Formation, a saline aquifer approximately 1km below the surface and 200km from the coast. Statoil, the field operator, has injected almost 1Mt/yr of captured CO2 into the storage site since 1996. The buoyant CO2 plume ascended rapidly through eight thin shale barriers within the aquifer to reach the top seal in less than three years. The plume's progress has been monitored by eight seismic surveys, as well as gravimetric and electromagnetic monitoring, which record the spreading of nine thin CO2 layers. This paper presents a capillary flow model using invasion percolation physics that accurately matches the plume's geometry. The approach differs from standard Darcy flow simulations, which fail to match the plume geometry. The calibrated capillary flow simulation indicates that a mass balance for the plume is likely, but can only replicate the plume geometry if the thin intra-formational shale barriers are fractured. The model enables an estimate of the shale barrier behavior and caprock performance. The fractures are very unlikely to have been caused by CO2 injection given the confining stress of the rock and weak overpressure of the plume, and so fracturing must pre-date injection. A novel mechanism is suggested: the deglaciation of regional ice sheets that have rapidly and repeatedly unloaded approximately 1km of ice. The induced transient pore pressures are sufficient to hydro-fracture thin shales. The fractures enable fast CO2 ascent, resulting in a multi-layered plume. Shallow CO2 storage sites in the Northern North Sea and other regions that have been loaded by Quaternary ice sheets are likely to behave in a similar manner
Thermal atomic layer etching of germanium-rich SiGe using an oxidation and "conversion-etch" mechanism
The thermal atomic layer etching (ALE) of germanium-rich SiGe was demonstrated using an oxidation and "conversion-etch" mechanism with oxygen (O-2) or ozone (O-3), hydrofluoric acid (HF), and trimethylaluminum [TMA, Al(CH3)(3)] as the reactants. The crystalline germanium-rich SiGe film was prepared using physical vapor deposition and had a composition of Si0.15Ge0.85. In situ spectroscopic ellipsometry was employed to monitor the thickness of both the SiGe film and the surface oxide layer on the SiGe film during thermal ALE. Using a reactant sequence of O-2-HF-TMA, the etch rate of the SiGe film increased progressively with temperatures from 225 to 290 degrees C. At 290 degrees C, the SiGe film thickness decreased linearly at a rate of 0.57 angstrom /cycle with a surface oxide thickness of 18-19 angstrom. This etch rate was obtained using reactant pressures of 25, 0.2, and 0.4Torr and doses of 1.5, 1.0, and 1.0s for O-2, HF, and TMA, respectively. The TMA and HF reactions were self-limiting and the O-2 reaction was reasonably self-limiting at 290 degrees C. Using an O-3-HF-TMA reaction sequence, the SiGe ALE etch rate was 0.42 angstrom /cycle at 290 degrees C. This etch rate was obtained using reactant pressures of 15, 0.2, and 0.4Torr and dose times of 0.5, 1.0, and 1.0s for O-3, HF, and TMA, respectively. The O-3, TMA, and HF reactions were all self-limiting at 290 degrees C. Atomic force microscopy images revealed that thermal ALE with the O-2-HF-TMA or O-3-HF-TMA reaction sequences did not roughen the surface of the SiGe film. The SiGe film was etched selectively compared with Si or Si3N4 at 290 degrees C using an O-2-HF-TMA reaction sequence. The etch rate for the SiGe film was >10 times faster than Si(100) or Si3N4 that was prepared using low-pressure chemical vapor deposition. This selectivity for the SiGe film will be useful to fabricate Si nanowires and nanosheets using SiGe as the sacrificial layer.Peer reviewe
High‐Throughput Miniaturized Screening of Nanoparticle Formation via Inkjet Printing
This is the peer reviewed version of the following article:Ioanna D. Styliari, et al, ‘High‐Throughput Miniaturized Screening of Nanoparticle Formation via Inkjet Printing’, Macromolecular Materials and Engineering, (2018), which has been published in final form at https://doi.org/10.1002/mame.201800146. Under embargo until 27 May 2019. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.The self‐assembly of specific polymers into well‐defined nanoparticles (NPs) is of great interest to the pharmaceutical industry as the resultant materials can act as drug delivery vehicles. In this work, a high‐throughput method to screen the ability of polymers to self‐assemble into NPs using a picoliter inkjet printer is presented. By dispensing polymer solutions in dimethyl sulfoxide (DMSO) from the printer into the wells of a 96‐well plate, containing water as an antisolvent, 50 suspensions are screened for nanoparticle formation rapidly using only nanoliters to microliters. A variety of polymer classes are used and in situ characterization of the submicroliter nanosuspensions shows that the particle size distributions match those of nanoparticles made from bulk suspensions. Dispensing organic polymer solutions into well plates via the printer is thus shown to be a reproducible and fast method for screening nanoparticle formation which uses two to three orders of magnitude less material than conventional techniques. Finally, a pilot study for a high‐throughput pipeline of nanoparticle production, physical property characterization, and cytocompatibility demonstrates the feasibility of the printing approach for screening of nanodrug delivery formulations. Nanoparticles are produced in the well plates, characterized for size and evaluated for effects on metabolic activity of lung cancer cells.Peer reviewe
Sensitivity, reliability and construct validity of GPS and accelerometers for quantifying peak periods of rugby competition
Training prescription and monitoring of team-sport athletes rely on accurate quantification of player movement. Our aim was to determine the sensitivity, reliability and construct validity of measures derived from a wearable device incorporating Global Positioning System (GPS) and accelerometer technology to quantify the peak periods of rugby competition. Match movement data were collected from 30 elite and 30 sub-elite rugby union players across respective competitive seasons. Accelerometer and GPS measures were analysed using a rolling average to identify peak movement for epochs ranging from 5 to 600 seconds. General linear mixed modelling was used to quantify the effects of playing position and match-half on the peak movement and variabilities within and between players represented reliability of each measure. Mean positional differences and match-half changes were assessed via standardisation and magnitude-based decisions. Sensitivity of measures was quantified via evaluation of ("signal") and typical error of measurement ("noise"). GPS and accelerometer measures had poor sensitivity for quantifying peak movement across all epochs and both levels of rugby union competition (noise 4× to 5× the signal). All measures displayed correspondingly low reliability across most epochs and both levels of competition (ICC<0.50). Construct validity was evident in mean differences between playing positions and match halves that were consistent with expected activity profiles in rugby union. However, it was clear from the pattern of differences across epoch durations and levels of competition that GPS and accelerometer measures provided different information about player movement. The poor sensitivity and low reliability of GPS and accelerometer measures of peak movement imply that rugby union players need to be monitored across many matches to obtain adequate precision for assessing individuals. Although all measures displayed construct validity, accelerometers provided meaningful information additional to that of GPS. We recommend using accelerometers alongside GPS to monitor and prescribe match respresentative training
\u3ci\u3ePhotosystem II Subunit S\u3c/i\u3e overexpression increases the efficiency of water use in a field-grown crop
Insufficient water availability for crop production is a mounting barrier to achieving the 70% increase in food production that will be needed by 2050. One solution is to develop crops that require less water per unit mass of production. Water vapor transpires from leaves through stomata, which also facilitate the influx of CO2 during photosynthetic assimilation. Here, we hypothesize that Photosystem II Subunit S (PsbS) expression affects a chloroplastderived signal for stomatal opening in response to light, which can be used to improve wateruse efficiency. Transgenic tobacco plants with a range of PsbS expression, from undetectable to 3.7 times wild-type are generated. Plants with increased PsbS expression show less stomatal opening in response to light, resulting in a 25% reduction in water loss per CO2 assimilated under field conditions. Since the role of PsbS is universal across higher plants, this manipulation should be effective across all crops
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