26 results on '"H. Zondag"'
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2. Spray deposition inside multiple-row nursery trees with a laser-guided sprayer1
- Author
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R. H. Zondag, H. Liu, Hengyu Liu, H. Zhu, and Y. Shen
- Subjects
0106 biological sciences ,Sprayer ,Acoustics ,Nozzle ,04 agricultural and veterinary sciences ,Horticulture ,Environmental Science (miscellaneous) ,Laser ,01 natural sciences ,040501 horticulture ,law.invention ,Tree structure ,law ,visual_art ,Botany ,Sterling silver ,visual_art.visual_art_medium ,Environmental science ,0405 other agricultural sciences ,010606 plant biology & botany - Abstract
Multiple-row container-grown trees require specially designed sprayers to achieve efficient spray delivery. A five-port air-assisted sprayer with both automatic and manual control modes was developed to discharge adequate spray deposition inside multiple-row trees. The sprayer resulted from integration of a high-speed laser-scanning sensor with a sophisticated nozzle flow control system, an embedded computer with a touch screen, a Doppler speed sensor, a specially-designed algorithm and an air-assisted sprayer base. It was able to detect target tree presence and measure target tree size, shape and leaf density. The sprayer then controlled the spray output of each nozzle to match tree structures. The sprayer was tested for its sprayer deposition quality inside canopies in a four-row sterling silver linden (Tilia tomentosa 'Sterling Silver' Moench) field and another six-row northern red oak (Quercus rubra L.) field. Tests were conducted with the sprayer in variable-rate application (VRA) and constant-rate application (CRA) modes. The average spray deposit on foliage of trees was 1.37±0.47 μL cm−2 from VRA and 1.29±0.42 μL cm−2 from CRA in linden, and was 2.15±0.57 μL cm−2 from VRA and 2.72±0.94 μL cm−2 from CRA in red oak, respectively. In comparison, spray coverage on foliage of trees was 19.8±3.0% from VRA and 20.9±4.3% from CRA in the linden trial, and was 27.9±3.7% from VRA and 30.5±5.4% from CRA, respectively, in the red oak trial. The newly developed air-assisted sprayer in both VRA and CRA modes would be able to discharge adequate spray deposition inside multiple-row tree plants while conserving pesticide. Index words: environmental protection, pest control, pesticide, precision sprayer, spray coverage. Species used in this study: sterling silver linden (Tilia tomentosa 'Sterling Silver' Moench), northern red oak (Quercus rubra L.).
- Published
- 2017
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3. Applications of Thermal Energy Storage in the Energy Transition: Benchmarks and Developments
- Author
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Duncan Gibb, Antje Seitz, Maike Johnson, Joaquim Romaní, Jaume Gasia, Luisa F. Cabeza, Richard Gurtner, Lars Reinholdt, Erasmus Rothuizen, P. A. Sorensen, J. F. Fourmigué, S. Rougé, D. Haillot, J.P.Bédécarrats, S. Belik, T. Bauer, S. Zunft, T. Urbaneck, A. Vandersickel, S. Vasta, V. Palomba, T. Nomura, Y. Kato, R. de Boer, H. Zondag, A. Sevault, U. Dar, E. Grønnesby, A. Campos-Celador, G. Diarce, P. Löveryd, K. Friman, A. S. Kalagasidis, P. Johansson, P. Tan, N. Stathopolous, S. N. Gunasekara, J. Chiu, M. Bunea, B. Koçak, and H. Paksoy
- Subjects
reactions ,adsorption ,PCM ,thermal energy storage ,sensible heat ,annex 30 - Abstract
Thermal energy storage technologies occupy a unique position in the energy sector. On the one hand, the basic principles of storing heat have been understood for well over a century and applied in domestic and industrial settings. This includes concepts as fundamentalas hot water heaters or regenerator heat storages in steelmaking processes. These technologies are well-established within their respective sectors and have contributed to the efficient and convenient use of heat in many ways.On the other hand, there are novel applicationsof thermal storage that are beginning to be exploited and new technologies that are being applied in innovative ways. The story begins with classical technologies that are currently finding new uses in power plants, district heating grids and industrial processesin order to provide a wide range of benefits. These include energy efficiency in processes, increased use of renewable energy and cost savings. In addition to this, there have been technological developments that are opening new doors within well-known applications. Some suitable examples are the cost-effective storage of molten salts in a thermocline, high-temperature latent heat storage for high power levels and thermochemical reactions that can store heatloss-free. The evolution of the energy system has furthermore led to new possibilities for the usageof heat.It is beginning to be recognized that thermal energy storage is an enabling and cross-cutting technology that can unlock potentials in various sectors. By facilitating the coupling of the electricity and heat sectors, it is emerging as a key solution for the energy transition that improves thermal and electrical energy management in a flexible and reliable manner. Annex 30 has worked to advance the implementation of thermal energy storage systems by developing an analysis methodology for storage integration, determining key performance indicators and collecting and analyzing case studies of TES systems integrated in processes.
- Published
- 2018
4. LASER TAG: INTELLIGENT SPRAYERS CHANGE THE PEST MANAGEMENT GAME©
- Author
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R. H. Zondag, Heping Zhu, Amy Fulcher, Diana Cochran, and R. Rosetta
- Subjects
Integrated pest management ,Engineering ,Agroforestry ,business.industry ,Horticulture ,business - Published
- 2014
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5. Fertilizer Applications for Container-Grown Ornamental Tree Production
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T. Demaline, R. H. Zondag, James C. Locke, Charles R. Krause, H. Zhu, J. Merrick, and H. Y. Jeon
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Canopy ,Irrigation ,Growing season ,Horticulture ,Environmental Science (miscellaneous) ,engineering.material ,Potting soil ,Potting ,Nutrient ,Ornamental plant ,engineering ,Environmental science ,Fertilizer - Abstract
Better management of nutrient applications during a growing season is needed to economically produce marketable container-grown ornamental shade trees. Fertilizer practices were used to test the growth of Acer rubrum ‘Red Sunset’ trees in two commercial nursery fields (each containing four plots) that were irrigated with either city or pond water. In each field, the same 16 treatments were replicated. Two slow-release granular fertilizers (18-5-12 and 12-0-42) were applied separately or together by incorporation, topdress or both to a potting mix for trees grown in 26 liter (7 gal) containers and placed above or below ground. Trees irrigated with pond water also received supplemental liquid nutrients throughout the growing season along with nitric acid to lower the pH of the potting substrate. Tree growth was assessed by stem diameter (caliper), height, canopy size, leaf color and root measurements. Significant higher caliper increases occurred in trees treated with 18-5-12 fertilizer and irrigated with either pond or city water than trees treated with the 12-0-42 fertilizer. Significantly higher percent increases in caliper also occurred for trees irrigated with pond water and top-dressed with 18-5-12 fertilizer than trees with incorporated 18-5-12 fertilizer. With the same slow-release fertilizer applications, trees irrigated with pond water and supplemental nutrients had greater percent increases of caliper, larger canopy areas and better root systems than trees irrigated with city water. The differences in tree height increase were not as great as the caliper increases. However, tree growth irrigated with pond water required additional inputs with extra nutrients and labor costs throughout the growing season.
- Published
- 2013
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6. Reduced Use of Pesticides for Effective Controls of Arthropod Pests and Plant Diseases
- Author
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Heping Zhu, Jay Daley, Jim Merrick, Charles R. Krause, and Randall H. Zondag
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Toxicology ,Aphid ,Pesticide use ,biology ,fungi ,Ornamental plant ,Arthropod ,Horticulture ,Environmental Science (miscellaneous) ,Pesticide ,biology.organism_classification - Abstract
Current label recommendations of pesticides for arthropod pests and plant diseases in the nursery and green industry are vague and frequently result in excessive pesticide use. The objective of this research was to demonstrate that modifications of spray application techniques with current spray equipment in ornamental nursery production could reduce pesticide use. The efficacy of half rates and full rates of both active ingredients and carrier was investigated in commercial nurseries with air-assisted sprayers in two tests and a state inspector survey for the control of arthropod pests and plant diseases. Sprayers were optimized with properly sized nozzles and properly calibrated operating parameters. In Test 1, treatments were conducted in approximately 0.5 ha (1.2 A) plot each in three commercial nurseries for control of arthropod pests and diseases, and in Test 2, the same treatment for aphid control was evaluated in a birch tree plot. The survey was a compilation of the pests and diseases that were diagnosed by state inspectors in over 2,800 plant varieties and species from two commercial nursery fields [total about 280 ha (692 A)] after the spray treatments in six growing seasons. Crop damage by 49 insects and 40 diseases were surveyed for different application rates. The studies revealed that insect and disease control using 50% of the label rates was as effective as full rates when quality spray coverage on targets was achieved, resulting in real cost benefits to producers, consumers and the environment.
- Published
- 2011
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7. COMPARISON OF IRRIGATION, LEACHATE AND TREE GROWTH BETWEEN SOILLESS AND COAL ASH BASED MEDIA
- Author
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L. Chen, R. H. Zondag, H. Zhu, J. M. Frantz, and R. Krause
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Irrigation ,Moisture ,business.industry ,Coal combustion products ,Drip irrigation ,Horticulture ,engineering.material ,Fly ash ,Bottom ash ,engineering ,Environmental science ,Coal ,Fertilizer ,business - Abstract
In nursery production, knowledge of water quality and quantity is needed to improve irrigation and fertilizer application efficiency as it relates to potential for soil and groundwater contamination. Water and fertilizer use and loss as well as tree growth were investigated for Red Sunset maple (Acer rubrum 'Franksred') trees in a pot-in-pot system with two different potting media and one coal ash based medium. The coal ash based medium (Mix #1) was mainly composed of biosolids, flue gas desulfurization gypsum, and coal combustion bottom ash. The two potting media mainly composed of aged pine bark and steamed composted nursery trimmings as well as left-over potting medium from commercial nurseries, but one with low initial amendments (Mix #2) and the other one with high initial amendments (Mix #3). Trickle irrigation was applied to each tree with an automatic control system. Watering trees started when the medium moisture was below 30%, and stopped when the moisture was 42%. During two-year tests, the amount of water including irrigation and rainfall applied to each tree with Mix #1, #2 and #3 was 741, 910 and 950 L, respectively. The amount of water loss through drainage for each tree with Mix #1, #2 and #3 was 107, 147 and 112 L, respectively. Among the tree media, Medium #3 produced the highest tree growth rate, followed by the Mix #2. The coal ash based medium had great potentials to be used for nursery production.
- Published
- 2009
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8. Influence of Spray Volume on Spray Deposition and Coverage within Nursery Trees
- Author
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Charles R. Krause, Michael E. Reding, R. C. Derksen, R. H. Zondag, and Heping Zhu
- Subjects
Horticulture ,Waste management ,Volume (thermodynamics) ,Sprayer ,Environmental science ,Acre ,Environmental Science (miscellaneous) ,Deposition (chemistry) ,Spray volume - Abstract
Information on better utilizing airblast sprayers to achieve high pesticide spray application efficiency in nursery tree production is needed. Foliar spray deposition and coverage at different heights inside crabapple tree canopies were investigated for a conventional airblast sprayer operating at four different application rates ranging from 230 to 900 liters/ha [24 to 94 gallons per acre (GPA)]. Deposition on the ground at various distances from the sprayer was also measured at the 700 liters/ha (73 GPA) application rate. Foliar deposition and coverage on targets below 2.6 m (8.5 ft) inside tree canopies increased as the application rate increased, but the increase in the coverage was much lower than the deposition. For trees taller than 2.6 m (8.5 ft), the sprayer could not deliver uniform spray deposition and coverage across the tree height. The portion of trees below 2.1 m (6.9 ft) was well covered by the spray deposits with 230 liters/ha (24 GPA) application rate while higher application rates resulted in over spray application. Less than 30% of total spray volume was deposited on target trees while over 34% of the total spray volume was lost on the ground. The tree-row volume method should include foliage density and tree-row gaps to avoid excessive estimation of spray application rates for nursery tree crops.
- Published
- 2008
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9. Effect of Application Variables on Spray Deposition, Coverage, and Ground Losses in Nursery Tree Applications
- Author
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R. H. Zondag, R. C. Derksen, Charles R. Krause, Ross D. Brazee, and Robert D. Fox
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Canopy ,Hydrology ,Tree canopy ,biology ,Sprayer ,Horticulture ,Environmental Science (miscellaneous) ,biology.organism_classification ,Volume (thermodynamics) ,Ground speed ,Environmental science ,Orchard ,Row ,Corylus colurna - Abstract
An experimental cross-flow (CF) fan sprayer and a conventional, axial-fan (AF), orchard sprayer were used to treat multiple rows consisting of four year old, multi-stem, red maple trees, Acer rubrum L. and Turkish filbert trees, Corylus colurna L. The effects of sprayer type, fan orientation, application volume, and ground speed on canopy and ground spray deposits and canopy spray coverage across multiple target rows were evaluated. Variations in deposits and coverage across the canopies were generally smaller for the CF sprayer than the AF sprayer. The AF sprayer produced the highest overall deposits in the first row nearest the sprayer. Reducing fan speed kept more material in the tree row adjacent to the sprayer while decreasing spray volume did not affect the spray deposits in that row. Tower sprayer fan orientation did not affect canopy deposits but could be used to minimize spray drift. These results indicate that the most uniform spray distribution in a tree canopy is obtained by treating the canopy from each side. These findings also suggest growers should experiment with different spray volume and speed settings that can provide efficacious applications more efficiently.
- Published
- 2006
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10. An assessment of household willingness to pay for curbside recycling: A comparison of payment card and referendum approaches
- Author
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Keith R. Jones, Randall H. Zondag, Frank R. Lichtkoppler, and Thomas W. Blaine
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Conservation of Natural Resources ,Family Characteristics ,Health Services Needs and Demand ,Contingent valuation ,Environmental Engineering ,Actuarial science ,Public economics ,Cost-Benefit Analysis ,Community Participation ,General Medicine ,Management, Monitoring, Policy and Law ,Space (commercial competition) ,Payment card ,Identification (information) ,Goods and services ,Willingness to pay ,Referendum ,Economics ,Humans ,Regression Analysis ,Policy Making ,Explanatory power ,Waste Management and Disposal ,Social Welfare - Abstract
Curbside recycling is a tool that communities use to reduce the need for landfill space. This study provides contingent valuation estimates of household willingness to pay (WTP) to continue a curbside recycling program in the face of budget cuts. Comparisons of two forms of the contingent valuation method (CVM) are provided: a single bounded referendum and a payment card. Neither approach emerges as unambiguously superior. Response rates were virtually identical. Both approaches show that support for curbside recycling is highly sensitive to price. Regression results from the payment card provided a more thorough identification of socio-demographic variables associated with WTP than the referendum, but the explanatory power of the two regressions did not differ significantly. The referendum estimates of mean WTP exceed those from the payment card, although the disparities are less than those typically reported in the CVM literature. Local policy makers cited the CVM results as influencing their decisions regarding funding options for the future of the program, and seemed to appreciate the fact that the two approaches provided a fairly narrow range of estimates of WTP. In an era when more of the burden of financing of environmental programs is being shifted to the local level, use of CVM to estimate the WTP of consumers for highly disaggregated goods and services designed to achieve environmental improvement will likely become more relevant to local decision makers who are interested in understanding their constituents' views.
- Published
- 2005
- Full Text
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11. Spray Delivery to Nursery Trees by Air Curtain and Axial Fan Orchard Sprayers
- Author
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Charles R. Krause, Ross D. Brazee, R. H. Zondag, R. C. Derksen, and Robert D. Fox
- Subjects
Canopy ,Tree canopy ,Mechanical fan ,Test site ,Sprayer ,Single row ,Nozzle ,Environmental engineering ,Environmental science ,Horticulture ,Environmental Science (miscellaneous) ,Orchard - Abstract
Two types of air-assist sprayers were used to treat, from one side only, a single row of hedge-pruned, red maple (Acer rubrum L. ‘Red Sunset’) trees in a commercial Ohio nursery. A traditional orchard type sprayer and a prototype air curtain sprayer using crossflow fans and hydraulic nozzles were evaluated for differences in canopy deposits, spray coverage, and downwind ground deposits. The air curtain sprayer produced more uniform deposits vertically but not higher mean deposits than the traditional orchard type sprayer. The air curtain sprayer also produced somewhat higher ground deposits downwind of the treatment area. There were no differences in spray coverage between sprayers despite differences in the droplet spectrum produced by each sprayer. Evidence from the coverage and ground target samples indicate that slower fans on the air curtain sprayer might be needed to reduce air speed to retain more spray within the tree canopy. As operated, neither of the sprayers can be expected to produce uniform spray deposits around the nursery stock if treatments are made from one side of the row only. Canopy and ground target deposits indicate that alternate row spraying will not necessarily produce uniform deposits across two tree rows as planted at the test site.
- Published
- 2004
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12. REAL-TIME MEASUREMENT OF DRAINAGE FROM POT-IN-POT CONTAINER NURSERIES
- Author
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Charles R. Krause, Ross D. Brazee, R. C. Derksen, N. R. Fausey, R. H. Zondag, and Heping Zhu
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Hydrology ,Irrigation ,Volume (thermodynamics) ,Rain gauge ,Hydraulic engineering ,Maximum difference ,Environmental engineering ,Environmental science ,Drainage ,Container (type theory) ,Agricultural and Biological Sciences (miscellaneous) ,Weather station - Abstract
In pot-in-pot nursery production, information on the amount of drainage water loss from the pots due to irrigation and rainfall is beneficial to improving irrigation water use efficiency and optimizing nutrition management. An experimental field site was established to determine drainage water loss from pot-in-pot container nurseries with micro-irrigation. The site consisted of 50 container-grown trees, 10 tipping-bucket rain gauge units, and a portable weather station. Rain gauge units were calibrated four different ways to determine repeatability and reliability for real-time measurement of the drainage water. Volume of water was calculated from the product of number of tips and volume per tip. Accuracy of measurements was verified by the amount of drainage water collected weekly in collection buckets located under rain gauge units for various irrigation applications and rainfall events. The maximum difference in the weekly amount of drainage water collected with the collection buckets and measured with the rain gauge units was 1.215 L (or 5.3% error) when the daily irrigation application to five trees was 15.5 L. The system reported real-time measurement of drainage water due to irrigation and rainfall, and provided a research tool to evaluate strategies for nurseries to better manage irrigation schedules.
- Published
- 2004
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13. DETECTION AND QUANTIFICATION OF NURSERY SPRAY PENETRATION AND OFF-TARGET LOSS WITH ELECTRON BEAM AND CONDUCTIVITY ANALYSIS
- Author
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Ross D. Brazee, L. E. Horst, Heping Zhu, Charles R. Krause, R. C. Derksen, R. H. Zondag, and Robert D. Fox
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Canopy ,biology ,Sprayer ,Chemistry ,Thermal conductivity detector ,Analytical chemistry ,Soil science ,Penetration (firestop) ,Conductivity ,biology.organism_classification ,Agricultural and Biological Sciences (miscellaneous) ,food.food ,Tsuga ,food ,TRACER ,Gleditsia triacanthos - Abstract
Spray penetration and off-target loss from a conventional, air-assist, axial-fan sprayer and a high-clearance, boom-type sprayer were investigated in Honey Locust (Gleditsia triacanthos) and Canadian Hemlock (Tsuga canadensis) trees located in two different production nurseries. Aqueous tracer solutions of either Ca(NO3)2 foliar fertilizer or Cu(OH)2 fungicide were used in the experiments. Spray deposition distributions within canopies and off-target loss to drift and the ground were assessed via residues collected on foliage, electron microscope stubs, artificial plates, vertical and ground-level profile plastic tapes, and high-volume air samplers. Electron beam analysis (EBA) was used to assay residues on stubs, leaves, and needles placed and collected at several locations and heights in the canopy. Plastic tape samples were evaluated with a laboratory spray deposit analyzer using a conductivity detector. Both assessment methods used in the present study were useful for detection and quantification of Ca or Cu spray penetration within nursery canopies. The average spray deposit on upper surfaces of leaves was three times that deposited on lower surfaces within the Honey Locust trees. Spray deposit at the top of Canadian Hemlock tree canopies was 14 times higher than that at the middle and bottom of canopies. Spray deposit on ground targets greatly decreased as the distance from the spray path increased in both nurseries; however, airborne spray deposits did not decrease as much with increasing downwind distance as ground deposits.
- Published
- 2004
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14. Influence of travel speed on spray deposition uniformity from an air-assisted variable-rate sprayer
- Author
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Yue Shen, Heping Zhu, Hui Liu, Yu Chen, Erdal H. Ozkan, and Randall H. Zondag
- Subjects
Canopy ,Hydrology ,Deposition (aerosol physics) ,Sprayer ,Environmental science ,Orchard ,Tree species - Abstract
A newly developed LiDAR-guided air-assisted variable-rate sprayer for nursery and orchard applications was tested at various travel speeds to compare its spray deposition and coverage uniformity with constant-rate applications. Spray samplers, including nylon screens and water-sensitive papers (WSP), were mounted inside tree canopies to measure spray deposits and coverage. Experiments were conducted with six different size tree species in commercial nurseries and travel speeds ranged from 3.2 to 8.0 km h-1. Test results showed that variable-rate sprayer was able to adjust spray outputs to match canopy structures and travel speeds. For the variable-rate application, there were no significant variations in spray deposits and coverage for each tree species among the travel speeds of 3.2, 5.6 and 8.0 km h-1. The variable-rate application had significantly lower variations in spray deposits within canopies of different size trees than the constant spray application.
- Published
- 2013
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15. The discrimination potential of radio-opaque composite restorations for identification: part 3
- Author
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H, Zondag and V M, Phillips
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Observer Variation ,Dental Materials ,Contrast Media ,Forensic Anthropology ,Humans ,Bicuspid ,Zirconium ,Dental Restoration, Permanent ,Silicon Dioxide ,Composite Resins ,Radiography, Bitewing ,Models, Dental ,Forensic Dentistry - Abstract
The methods used for disaster victim identification is comparative postmortem profiling of dental and fingerprint data. Twelve dental concordant features are normally required for dental identification. The radiographic image of dental amalgam restorations has been shown to be highly significant for identification purposes. The aim of this study was to investigate the radiological morphology of standardized radio-opaque composite fillings in premolar teeth with regard to their discriminatory potential for identification purposes. Thirty lower first premolar teeth ("Typodont" acrylic teeth) that were filled with 3- surface fillings (MOD) radio-opaque composite resin (Z100) by 4th year dental students were used for this study. Bitewing radiographs were taken of all thirty fillings and labeled Set 1. A second set (Set 2) consisted of 10 randomly selected duplicate radiographs of Set 1, plus 2 other radiographic images not from Set 1. Instructions were given to 20 dentally trained examiners to match the 12 radiographic images of Set 2 with the 30 images of Set 1. The results showed that 18 of the 20 examiners correctly matched the 12 radiographic images, one scored 11 out of 12 and one scored 10 out of 12. This study shows that if the ante-mortem and post-mortem radiographs of a single composite filling have exactly the same morphology, this image is unique and 12 concordant features are not necessary for dental identification.
- Published
- 2012
16. Off-target loss in ornamental nurseries with different spray techniques
- Author
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H, Zhu, R C, Derksen, C R, Krause, and R H, Zondag
- Subjects
Aerosols ,Air Pollutants ,Agriculture ,Wind ,Models, Theoretical ,Pesticides ,Environmental Monitoring - Abstract
Information is lacking on spray techniques to reduce off-target loss on the ground and via spray drift from the treated area in nursery applications. Airborne deposits at three elevations on sampling towers and on the ground at several distances from the sprayer were investigated with the three spray treatments in an open field without crops. Tests were conducted with an air blast sprayer equipped with conventional hollow cone nozzles (HC), low drift nozzles (AI), and conventional hollow cone nozzles with a drift retardant (HCDR) in an open field without crops. To compare field test results, wind tunnel experiments were conducted to assess spray deposits on the floor beyond 0.4 m downwind distance from the nozzles and airborne deposits at 2.1 m downwind from the spray discharge point with the three spray techniques. Droplet size distributions across spray patterns were measured with a laser particle/droplet image analysis system. There was no significant difference in airborne deposits for the three elevations at both 15 and 30 m downwind from the sprayer between AI and HC methods except for 3.05 m elevation at the 15 m distance although the average airborne deposits with AI were lower than that with HC. The downwind spray deposits on the ground at 15 and 30 m from the sprayer with AI were higher than that with HC and HCDR. Compared with conventional hollow cone nozzles, drift reduction from air induction nozzles or the spray mixture with drift retardant was significant in wind tunnel tests but was not significant in field tests.
- Published
- 2010
17. Effects of sprayer configuration on efficacy for the control of scab on crabapple using electron beam analysis
- Author
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Charles R. Krause, Heping Zhu, Randall H. Zondag, Leona Horst, and R. C. Derksen
- Subjects
Malus ,Residue (complex analysis) ,biology ,Chemistry ,Sprayer ,X-Rays ,biology.organism_classification ,Atomic and Molecular Physics, and Optics ,Conidium ,Fungicides, Industrial ,Fungicide ,Plant Leaves ,Horticulture ,Ascomycota ,Apple scab ,Microscopy, Electron, Scanning ,Mancozeb ,Cultivar ,Pest Control ,Instrumentation ,Plant Diseases - Abstract
Foliar diseases like apple scab result in significant economic losses to growers each year. Assessment in past studies involved only macroscopic disease ratings. More complete knowledge of the fate and behavior of fungicide has been needed to reduce pesticide use with less off-target contamination. Field studies were conducted in a production nursery for over 4 years. A moderately susceptible cultivar of ornamental crabapple, Malus spp. cv “Candied Apple”, was sprayed with a fungicide using two sprayer/nozzle configurations. The fungicide used in this study was Mankocide, combination of Cu(OH)2 and mancozeb that permitted electron beam analysis (EBA) identification based on the presence of Cu, MN and Zn in the molecule and formulation. EBA was conducted using a cold field emission scanning electron microscopy and energy dispersive x-ray microanalyzer. Fresh leaf samples were placed on sticky stubs after each fungicide treatment. The presence or absence of fungal conidia and fungicide residue were measured. EBA permitted direct visualization and identification of the pathogens, morphologically, and chemical characterization of fungicide present. EBA was useful to quantify disease control related to fungicide coverage, sprayer configuration and treatment efficacy. SCANNING 31: 24–27, 2009. Published 2009 by Wiley Periodicals, Inc.
- Published
- 2009
18. An Empirical Study into the State of Practice and Challenges in IT Project Portfolio Management
- Author
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H. Zondag, Michel R. V. Chaudron, and E. Gleisberg
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Process management ,Empirical research ,Application portfolio management ,business.industry ,Key (cryptography) ,Systems engineering ,IT portfolio management ,Portfolio ,Project management ,Project portfolio management ,Investment (macroeconomics) ,business - Abstract
Optimizing IT investments in alignment with key business drivers is a challenge for all organizations. Organizations need to prioritize and select a portfolio of IT projects that provides optimal benefit and balances utility, risk, and resources. This paper reports on an exploratory empirical study into the processes and project-selection criteria used by several large companies. The objective of this research is to identify successful practices as well as some common challenges that companies have in performing IT portfolio management. These empirical findings provide insight into the current state of practice and common challenges. These form the basis for guidelines for implementing and improving IT portfolio processes.
- Published
- 2008
- Full Text
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19. Spray deposition and off-target loss in nursery tree crops with conventional nozzle, air induction nozzle and drift retardant
- Author
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Heping Zhu, Michael E. Reding, R. C. Derksen, Charles R. Krause, Ross D. Brazee, Robert D. Fox, H. Erdal Ozkan, and Randall H. Zondag
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Hydrology ,Deposition (aerosol physics) ,Sprayer ,Nozzle ,Significant difference ,Environmental engineering ,Particle ,Environmental science ,Droplet size ,Fire retardant ,Spray nozzle - Abstract
Spray deposits at various elevations within crabapple trees and on the ground were investigated with an air blast sprayer equipped with conventional hollow cone nozzles, air induction nozzles, and conventional hollow cone nozzles with a drift retardant in a commercial nursery field. Airborne deposits at three elevations on sampling towers and on the ground at several distances from the sprayer were also investigated with the three spray treatments in an open area without trees. Droplet size distributions across spray patterns were measured with a laser particle/droplet image analysis system. In general, there was no significant difference for deposits within nursery tree canopies and on the ground with three different spray techniques. With the 700 L/ha application rate, which was 360 L/ha lower than the rate normally used in nursery application, the tree canopies received over 4 to 14.5 times spray deposits actually needed from the air blast sprayer with the three spray techniques, and a large portion of spray droplets deposited on the ground.
- Published
- 2005
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20. New Techniques for Monitoring Drip Irrigation Water Use Efficiency, Drainage, and Leachate in Container Nurseries
- Author
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Norman R. Fausey, Charles R. Krause, Randall H. Zondag, Heping Zhu, R. C. Derksen, and Ross D. Brazee
- Subjects
Hydrology ,Irrigation ,Hydrology (agriculture) ,Moisture ,Environmental engineering ,Environmental science ,Water quality ,Drip irrigation ,Watertable control ,Drainage ,Water content - Abstract
Techniques are needed to ecologically monitor nursery production practices with proper use of water resource and nutrient management. An experimental system to examine water quality, irrigation efficiency and drainage from pot-in-pot nursery container production was established in a commercial nursery field. The system mainly consisted of a plot containing 50 trees planted in 50 pot-in-pot containers and irrigated with micro spray stakes; 10 drainage water measurement devices; 10 pot media moisture probes; 10 thermocouples; a weather station and a data logger. Preliminary tests indicated the system was feasible to monitor water inputs, drainage water loss, medium moisture content and temperature, leachate of nitrogen, phosphate and potassium in drainage water, rainfall and weather conditions, and tree growth in pot-in-pot nursery production.
- Published
- 2004
- Full Text
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21. Incident urogenital and anorectal Chlamydia trachomatis in women: the role of sexual exposure and autoinoculation: a multicentre observational study (FemCure).
- Author
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Dukers-Muijrers NHTM, Schim van der Loeff M, Wolffs P, Bruisten SM, Götz HM, Heijman T, Zondag H, Lucchesi M, De Vries H, and Hoebe CJPA
- Subjects
- Chlamydia trachomatis genetics, Cohort Studies, Female, Humans, Prospective Studies, Sexual Behavior, Chlamydia Infections epidemiology, Gonorrhea epidemiology
- Abstract
Background: Anorectal infections with Chlamydia trachomatis (CT) are common in women visiting STI outpatient clinics. We here evaluated the risk posed by sexual exposure and by alternate anatomical site infection for incident anorectal and urogenital CT., Methods: Prospective multicentre cohort study, FemCure. Participants were treated for CT, and after 4, 6, 8, 10 and 12 weeks, they self-collected anorectal and urogenital samples (swabs) for CT-DNA testing. We calculated the proportion with incident CT, that is, CT incidence (at weeks 6-12) by 2-week time-periods. Compared with no exposure (A), we estimated the risk of incident CT for (B) sexual exposure, (C) alternate site anatomic site infection and (D) both, adjusted for confounders and expressed as adjusted ORs with 95% CIs., Results: We analysed data of 385 participants contributing 1540 2-week periods. The anorectal CT incidence was 2.9% (39/1343) (95 CI 1.8 to 3.6); 1.3% (A), 1.3% (B), 27.8% (C) and 36.7% (D). The ORs were: 0.91 (95% CI 0.32 to 2.60) (B), 26.0 (95% CI 7.16 to 94.34) (C), 44.26 (95% CI 14.38 to 136.21) (D).The urogenital CT incidence was 3.3% (47/1428) (95% CI 2.4 to 4.4); 0.7% (A), 1.9% (B), 13.9% (C) and 25.4% (D). The ORs were: 2.73 (95% CI 0.87 to 8.61) (B), 21.77 (95% CI 6.70 to 70 71) (C) and 49.66 (95% CI 15.37 to 160.41) (D)., Conclusions: After initial treatment, an alternate anatomical site CT infection increased the risk for an incident CT in women, especially when also sex was reported. This may suggest a key role for autoinoculation in the re-establishment or persistence of urogenital and anorectal chlamydia infections., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.)
- Published
- 2022
- Full Text
- View/download PDF
22. Does Previous Syphilis Alter the Course of Subsequent Episodes of Syphilis?
- Author
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Schim van der Loeff MF, Zondag H, Bruisten S, and Jongen VW
- Subjects
- Humans, HIV Infections, Syphilis complications, Syphilis diagnosis
- Published
- 2022
- Full Text
- View/download PDF
23. Assessment of TB treatment on patient well-being.
- Author
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Schultink MP, Kerstjens HAM, Ter Beek L, Zondag H, Brijan R, de Lange WCM, van der Werf TS, and Akkerman OW
- Subjects
- Humans, Tuberculosis, Pulmonary
- Published
- 2021
- Full Text
- View/download PDF
24. Reactive force field development for magnesium chloride hydrates and its application for seasonal heat storage.
- Author
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Pathak AD, Nedea S, van Duin AC, Zondag H, Rindt C, and Smeulders D
- Abstract
MgCl2 hydrates are considered as high-potential candidates for seasonal heat storage materials. These materials have high storage capacity and fast dehydration kinetics. However, as a side reaction to dehydration, hydrolysis may occur. Hydrolysis is an irreversible reaction, which produces HCl gas thus affecting the durability of heat storage systems. In this study, we present the parameterization of a reactive force field (ReaxFF) for MgCl2 hydrates to study the dehydration and hydrolysis kinetics of MgCl2·H2O and MgCl2·2H2O. The ReaxFF parameters have been derived by training against quantum mechanics data obtained from Density Functional Theory (DFT) calculations consisting of bond dissociation curves, angle bending curves, reaction enthalpies, and equation of state. A single-parameter search algorithm in combination with a Metropolis Monte Carlo algorithm is successfully used for this ReaxFF parameterization. The newly developed force field is validated by examining the elastic properties of MgCl2 hydrates and the proton transfer reaction barrier, which is important for the hydrolysis reaction. The bulk moduli of MgCl2·H2O and MgCl2·2H2O obtained from ReaxFF are in close agreement with the bulk moduli obtained from DFT. A barrier of 20.24 kcal mol(-1) for the proton transfer in MgCl2·2H2O is obtained, which is in good agreement with the barrier (19.55 kcal mol(-1)) obtained from DFT. Molecular dynamics simulations using the newly developed ReaxFF on 2D-periodic slabs of MgCl2·H2O and MgCl2·2H2O show that the dehydration rate increases more rapidly with temperature in MgCl2·H2O than in MgCl2·2H2O, in the temperature range 300-500 K. The onset temperature of HCl formation, a crucial design parameter in seasonal heat storage systems, is observed at 340 K for MgCl2·H2O, which is in agreement with experiments. The HCl formation is not observed for MgCl2·2H2O. The diffusion coefficient of H2O through MgCl2·H2O is lower than through MgCl2·2H2O, and can become a rate-limiting step. The diffusion coefficient increases with temperature and follows the Arrhenius law both for MgCl2·H2O and MgCl2·2H2O. These results indicate the validity of the ReaxFF approach for studying MgCl2 hydrates and provide important atomistic-scale insight of reaction kinetics and H2O transport in these materials.
- Published
- 2016
- Full Text
- View/download PDF
25. A DFT-based comparative equilibrium study of thermal dehydration and hydrolysis of CaCl₂ hydrates and MgCl₂ hydrates for seasonal heat storage.
- Author
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Pathak AD, Nedea S, Zondag H, Rindt C, and Smeulders D
- Abstract
Salt hydrates store solar energy in chemical form via a reversible dehydration-hydration reaction. However, as a side reaction to dehydration, hydrolysis (HCl formation) may occur in chloride based salt hydrates (specially in MgCl2 hydrates), affecting the durability of the storage system. The mixture of CaCl2 and MgCl2 hydrates has been shown experimentally to have exceptional cycle stability and improved kinetics. However, the optimal operating conditions for the mixture are unknown. To understand the appropriate balance between dehydration and hydrolysis kinetics in the mixtures, it is essential to gain in-depth insight into the mixture components. We present a GGA-DFT level study to investigate the various gaseous structures of CaCl2 hydrates and to understand the relative stability of their conformers. The hydration strength and relative stability of conformers are dominated by electrostatic interactions. A wide network of intramolecular homonuclear and heteronuclear hydrogen bonds is observed in CaCl2 hydrates. Equilibrium product concentrations are obtained during dehydration and hydrolysis reactions under various temperature and pressure conditions. The trend of the dehydration curve with temperature in CaCl2 hydrates is similar to the experiments. Comparing these results to those of MgCl2 hydrates, we find that CaCl2 hydrates are more resistant towards hydrolysis in the temperature range of 273-800 K. Specifically, the present study reveals that the onset temperatures of HCl formation, a crucial design parameter for MgCl2 hydrates, are lower than for CaCl2 hydrates except for the mono-hydrate.
- Published
- 2016
- Full Text
- View/download PDF
26. The discrimination potential of radio-opaque composite restorations for identification: part 3.
- Author
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Zondag H and Phillips VM
- Subjects
- Bicuspid diagnostic imaging, Contrast Media chemistry, Humans, Models, Dental, Observer Variation, Silicon Dioxide chemistry, Zirconium chemistry, Composite Resins chemistry, Dental Materials chemistry, Dental Restoration, Permanent classification, Forensic Anthropology methods, Forensic Dentistry methods, Radiography, Bitewing statistics & numerical data
- Abstract
The methods used for disaster victim identification is comparative postmortem profiling of dental and fingerprint data. Twelve dental concordant features are normally required for dental identification. The radiographic image of dental amalgam restorations has been shown to be highly significant for identification purposes. The aim of this study was to investigate the radiological morphology of standardized radio-opaque composite fillings in premolar teeth with regard to their discriminatory potential for identification purposes. Thirty lower first premolar teeth ("Typodont" acrylic teeth) that were filled with 3- surface fillings (MOD) radio-opaque composite resin (Z100) by 4th year dental students were used for this study. Bitewing radiographs were taken of all thirty fillings and labeled Set 1. A second set (Set 2) consisted of 10 randomly selected duplicate radiographs of Set 1, plus 2 other radiographic images not from Set 1. Instructions were given to 20 dentally trained examiners to match the 12 radiographic images of Set 2 with the 30 images of Set 1. The results showed that 18 of the 20 examiners correctly matched the 12 radiographic images, one scored 11 out of 12 and one scored 10 out of 12. This study shows that if the ante-mortem and post-mortem radiographs of a single composite filling have exactly the same morphology, this image is unique and 12 concordant features are not necessary for dental identification.
- Published
- 2009
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