bluuebunny/crossref_metadata_2025 huggingface dataset:
Method for Quantifying Percentage Wood Failure in Block-Shear Specimens by a Laser Scanning Profilometer
Authors: Scott CT , Hernandez R , Frihart C , Gleisner R , Tice T
Published: April 2008

A new method for quantifying percentage wood failure of an adhesively bonded block-shear specimen has been developed. This method incorporates a laser displacement gage with an automated two-axis positioning system that functions as a highly sensitive profilometer. The failed specimen is continuously scanned across its width to obtain a surface failure profile. The laser is then moved incrementally along the length of the specimen and repeatedly scanned to obtain a three-dimensional digital profile of the surface. This digital profile can then be reconstructed and analyzed with appropriate software. Special algorithms are used to quantify percentage wood failure and degree of wood failure (depth of wood failure) and to recognize various surface anomalies, such as bondline voids. This paper presents exploratory data on several different types of wood failures and correlates these measurements to the visual inspections of skilled evaluators. The device is very sensitive to most observed failures, particularly those with deep wood failure. However, shallow failures close to the bondline can be problematic. The algorithms allow a “roughness” tolerance to be specified to characterize these surfaces. This new method will be useful for automating measurement of wood failure in block-shear specimens with good precision and repeatability.
The Study of Bond Strength and Bond Durability of Reactive Powder Concrete
Authors: Lee M-G , Chiu C-T , Wang Y-C
Published: April 2008

This research project aims to use reactive powder concrete, RPC. as a new repair material and evaluate its bond strength and bond durability to existing concrete. One accelerated aging environment, namely a freeze-thaw cycle acceleration deterioration test, was selected for the evaluation of bond durability of the repair materials. Before and after aging, the samples were evaluated by the compressive strength, bond strength (slant shear test), steel pull out strength, and relative dynamic modulus NDT tests.

The test results show that the RPC possesses high bond strength, dynamic modulus, and bond durability as compared with other concretes. The adhesion between the RPC and the steel is also much greater than that for the other concretes. It would be interesting to verify the consequences of this improved adhesion in reinforced concrete structures.

Test results revealed that RPC was still in good condition after 1000 cycles of freezing and thawing in accordance with ASTM C 666-97. After 1000 cycles, the nonshrinkage high strength mortar showed a reduction in compressive strength, slant shear strength, steel pull out strength, and dynamic modulus by 17, 21, 24, and 25 %, compared with the corresponding values of 6, 7, 5, and 10 %, respectively, for RPC. Specimens of normal strength concrete were used as reference specimens. The 5 cm × 10 cm slant shear cylinders made of normal strength concrete had deteriorated severely after 600–700 freeze-thaw cycles. For the normal strength concrete, the average values of relative dynamic modulus of elasticity based on resonant frequencies after 300 and 600 freeze-thaw cycles were 75 and 55 %, compared with the corresponding values of 96 and 92 %, respectively, for RPC.
New Technique for Measuring Extended Viscosity Ranges — Gel Times, Pot Life, or Cure Monitoring — with Programmable Rotational Viscometers or Rheometers
Authors: Moonay DJ
Published: April 2008

A new algorithm written in commercially available software controls programmable viscometers and rheometers so that multiple decades of apparent viscosity data may be acquired. This work is new and important because previous methods involved either: (1) very simple instrumentation providing (a) single-point viscosity data or (b) equipment providing “gel times” but no viscosity data, or (2) complicated instrumentation costing at least $20 000. Isothermal cure of a common epoxy system was successfully monitored in this work. Apparent viscosities measured during one room-temperature cure experiment ranged from approximately 1000 mPa·s to 50 000 000 mPa·s. Good repeatability of data was found for different batches prepared with similar stoichiometry. Viscosities measured at approximately 167 min of cure time, during multiple tests, differed by less than 1 %. Various test geometries were used, including disposable cylindrical spindles and sample chambers, to allow easy cleanup, with samples 10 mL or less in size. Samples were also successfully tested at 50 and 60°C. Aspects of the algorithm and its implementation are discussed. It is hoped that this new method will help personnel testing adhesives.
Retrieval Analysis of Cross-linked Acetabular Bearings
Authors: Collier JP , Mayor MB , Currier BH , Wittmann MW
Published: April 2008

Polyethylene acetabular bearings which have been purposely cross-linked with doses of radiation above the 2.5–4 Mrads historically used for sterilization are now being implanted clinically. While there are considerable data from hip simulators that suggest that the wear rate of these new, cross-linked materials may be lower than their predecessors [1], there are little clinical data available. This study provides the results of the analysis of six retrieved cross-linked acetabular bearings, all with implantation durations of less than two years.
Assessment of Surface Roughness and Waviness Using White Light Interferometry for Short-Term Implanted, Highly Crosslinked Acetabular Components
Authors: Kurtz SM , Turner J , Herr M , Edidin AA , Rimnac CM
Published: April 2008

The reduction of volumetric wear continues to be one of the imminent challenges for the orthopaedic research community in the area of ultra-high molecular weight polyethylene (UHMWPE) joint replacement components. Retrieval analyses are necessary to determine the relationship between in vitro hip simulator predictions and actual wear performance in vivo. To quantify short term wear in retrieved highly crosslinked acetabular components it is necessary to differentiate between the initial surface morphology (dominated by manufacturer's machining marks) and the smaller scale surface features associated with in vivo adhesive/abrasive wear mechanisms. We have developed and validated a technique for deconvolution of as-manufactured versus in vivo generated surface topology from retrieved, highly crosslinked polyethylene acetabular inserts. Surface topology was characterized by white light interferometry with advanced texture analysis software. A Fourier transform algorithm was used to deconvolve the low-frequency features (i.e., waviness) such as machining marks, from the high-frequency features (i.e., roughness). Twenty-one (21) short-term (less than 24 months) conventional and highly crosslinked retrievals from different manufacturers were evaluated in this study. The wear surfaces in the short-term retrievals were deconvolved using the cut-off frequencies from the new inserts. The frequency distribution and magnitude of the machining marks were found to be material and manufacturer specific. This study highlights the importance of quantitative techniques, such as white light interferometry for distinguishing between initial and in vivo generated surface morphology. The topology observed in the crosslinked retrievals was consistent with the surface damage mechanisms previously observed in conventional UHMWPE components, namely macroscopic and microscopic adhesive/abrasive wear.
The Wear of Highly Crosslinked UHMWPE in the Presence of Abrasive Particles: Hip and Knee Simulator Studies
Authors: Laurent MP , Blanchard CR , Yao JQ , Johnson TS , Gilbertson LN , Swarts DF , Crowninshield RD
Published: April 2008

The in-vitro wear behavior in the presence of abrasive particles was determined for two highly crosslinked ultrahigh molecular weight polyethylenes (HXPE), one in clinical application for hips and the other for knees. The wear studies were performed in joint simulators and were largely comparative, with conventional ultrahigh molecular weight polyethylene (UHMWPE) gamma irradiated 37 kGy in nitrogen used as the control. The test methodology used for these three-body wear tests was developed in-house. It was found that the wear advantage of the HXPEs relative to the conventional UHMWPE observed under clean conditions is largely preserved in the presence of the abrasive particles used (alumina and bone cement for hips, bone cement for knees) under the test conditions. These results suggest that the surface molecular chain orientation-inhibition mechanism proposed to account for the increased wear resistance of highly crosslinked polyethylenes undergoing micro adhesive/abrasive wear is still operational even when a thicker surface layer is disturbed in the presence of abrasive particles. Therefore, the wear of the UHMWPE is not simply dependent on the bulk mechanical properties of the UHMWPE. The higher than expected wear of the 22 mm hip liners compared to the 32 mm liners in the presence of abrasive particles suggests that the wear rate of the UHMWPE becomes stress dependent rather than load dependent for sufficiently high stresses.
The Effect of Reduced Fracture Toughness on Pitting and Delamination Type Wear of Elevated Cross-Linked Polyethylene
Authors: Maher SA , Furman BD , Wright TM
Published: April 2008

We hypothesized that the reduced fracture toughness associated with elevated cross-linking of ultra high molecular weight polyethylene would lead to an increase in pitting and delamination in specimens tested in a knee wear apparatus. Two blocks of compression molded polyethylene were electron beam irradiated, one block at 120 kGy, the other at 65 kGy; a third block was not irradiated to serve as a control. The 120 and 65 kGy blocks were post-irradiation heat treated. Wear, J-integral and tensile test specimens were machined from the blocks, and all specimens were sterilized, aged and tested. 65 kGy and 120 kGy irradiated material had significantly lower fracture toughness compared to the control material. Despite the reduced fracture toughness, no evidence of pitting, delamination, or subsurface damage occurred in the corresponding wear specimens after 2 million cycles. In contrast, half of the control specimens exhibited extensive pitting. Our hypothesis was rejected: reduced fracture toughness associated with the elevated cross-linked polyethylene groups was not associated with an increase in pitting and delamination type wear.
The Effect of Specimen Thickness on the Mechanical Behavior of UHMWPE Characterized by the Small Punch Test
Authors: Kurtz SM , Herr M , Edidin AA
Published: April 2008

The small punch test has been validated for Ultra High Molecular Weight Polyethylene (UHMWPE) in ASTM F 2183-02. Because only a limited volume of material may be available from retrieved components, reducing the specimen size may increase the number of test specimens. It is unknown if the reduction in specimen thickness will affect the small punch metrics. Therefore, the goal of this study was to examine the relationship between the small punch specimen thickness and the test metrics. Ram extruded GUR 1050 UHMWPE was used to make 5 small punch specimens (diameter 6.35 mm) for each of four different thicknesses: 0.25 mm, 0.33 mm, 0.43 mm, and 0.5 mm. Specimens were tested following ASTM F 2183-02. Power law-based scaling relationships were observed between normalized specimen thickness and the normalized peak load, ultimate load, and work-to-failure of the small punch test (R2 = 0.99, R2= 0.99, and R2=0.94, respectively). A nearly cubic relationship was observed between the normalized specimen thickness and the normalized initial stiffness, which was proportional to the elastic modulus of the UHMWPE, and was predicted based on beam theory (R2 =0.99). The results of this study provide indication of a reliable means for normalizing small punch test measurements to account for variations in specimen thickness.
Quantitative Habitat Analysis: A New Tool for the Integration of Modeling, Planning, and Management of Natural Resources
Authors: Marsh LK , Haarmann T
Published: April 2008

Federal laboratories are often caught between the need to meet mission objectives and the mandate to act as national stewards for natural resources. Following the initiation of the Manhattan Project in 1943, restricted land use at Los Alamos National Laboratory (LANL) retained many undisturbed areas that function as ecosystem sanctuaries for plants and animals throughout the 43 mi2 site. We developed a Quantitative Habitat Analysis (QHA) that enables both managers and scientists to better meet the goals of ecosystem management and sustainable development for LANL. QHA is a multi-faceted modeling, planning, and management tool with the goal of applying existing models in a new way. QHA provides an objective, standardized, and replicable system for management of wild areas by federal agencies. As part of the development of QHA, we reviewed 42 existing wildlife and habitat models, assessments, or evaluation methods and 12 computer programs. A pilot field study was conducted on 12 plots testing five different methods to determine the most suitable for data collection for the tool. Once methods were selected and models determined, a QHA application tool was created in ArcView to test the pilot data within the tool for user-friendly application. This year, 45 field sites were sampled. QHA currently comprises five main sub-models analyzed within a geographic information system using ArcView: 1) Ecological Land Classification (landscape level effects), 2) Rapid Ecological Assessment (general assessment)/U.S. National Vegetation Classification Element Occurrence (ecosystem “health”), 3) BEHAVE (wildfire and fuels monitoring), 4) Habitat Analysis and Modeling System (wildlife), and 5) ECORSK.6 (bio-contaminants). Key to this QHA tool was the use of “common currencies.” The common currencies consist of weighted scores that calculate a “grade” or means of comparison between different programs and scoring methods. Development and calibration of the QHA continues.
Predicting Biodiversity Potential Using a Modified Layers of Habitat Model
Authors: Kapustka LA , Galbraith H , Luxon M , Yocum JM , Adams WJ
Published: April 2008

Ecological resources of the 360-km2 Kennecott Utah Copper Corporation property in the Oquirrh Mountains has been studied since the 1970s. Detailed descriptions of the vegetation were undertaken in 1994 as part of a site-wide Ecological Risk Assessment (EcoRA). A vegetation map was produced from infrared aerial photographs and floristics lists were compiled for a site-wide ecological risk assessment. Vegetation cover was characterized using a relevé sampling procedure. Data from georeferenced relevé sampling points were used to propagate vertical structure characteristics across polygons. We adapted the Layers of Habitat HSI Model and calculated an index value for each polygon. Submontane shrub and the submontane shrub/desert shrub cover types comprised 32% and 12% respectively of the site-wide index; contributing more to the site-wide index than their area would suggest. Conversely, the grassland and salt desert shrub cover types contributed less to the site-wide index than their area would suggest. Index values were grouped into pentiles and the polygons were displayed in GIS format to illustrate the spatial distribution of structural diversity. The Layers of Habitat model is a surrogate for biodiversity (richness) potential. The spatial representation of structural diversity is being used to guide management practices to enhance site-wide biodiversity.
Development of HSI Models to Evaluate Risks to Riparian Wildlife Habitat from Climate Change and Urban Sprawl
Authors: Galbraith H , Price J , Dixon M , Stromberg J
Published: April 2008

Hitherto, HSI models have largely been utilized to quantify the quality of existing habitat for wildlife species, without reference to how that habitat may have been altered in the past or how it might be altered in the future. In this study, we are using HSI models as part of an integrated modeling approach to estimate the risk of habitat quality gain or loss for a variety of indicator species due to future climate change and aquifer management decisions at the San Pedro Riparian National Conservation Area (SPRNCA). Current anthropogenic stressors, including agricultural and municipal water use, are having adverse impacts on the extent and quality of riparian habitat in the SPRNCA. Future climate change, through its potential effects on hydrology and water demand by local communities, may exacerbate these effects. Because of these current and potential future changes, vertebrates that depend on riparian habitats for their breeding, wintering or migration sites are at risk. Combining climate, hydrology, and vegetation modeling with HSI models allows us to predict the effects these risks.
Toward an Ecological Framework for Assessing Risk to Vertebrate Populations from Brine and Petroleum Spills at Exploration and Production Sites
Authors: Efroymson RA , Carlsen TM , Jager HI , Kostova T , Carr EA , Hargrove WW , Kercher J , Ashwood TL
Published: April 2008

Brine and petroleum spills may affect terrestrial vertebrates through loss of reproductive habitat or reduced food availability rather than direct toxicity. A proposed ecological framework for evaluating impacts of these spills includes individual-based population models, a site conceptual trophic model, habitat suitability maps, and a stochastic brine spill generator. Simulation results for mammal populations in the Tallgrass Prairie Preserve petroleum exploration and production (E&P) site in Oklahoma are presented. The persistence of simulated American badger (Taxidea taxus) populations decreased with increasing brine spill area. The decline in persistence and average final population size was much steeper in highly fragmented landscapes. The simulated time to extinction for prairie vole (Microtus ochrogaster) populations showed a threshold at 30% habitat loss from spills; above this threshold the time to extinction decreased with increasing spill area. Vole density was sensitive to the interaction of predation and fragmentation, with fragmentation causing population extinction in the presence of predation, yet stabilizing the population in the absence of predation. We anticipate that our results will aid in future development of “exclusion criteria” for leaving unrestored habitat at E&P sites.
Beneficial Reuse of Foundry Sands in Controlled Low Strength Material
Authors: Dingrando JS , Edil TB , Benson CH
Published: April 2008

A study was conducted to determine how the unconfined compressive strength and flow of flowable fills prepared with foundry sand depends on the bentonite content of the sand. The study showed that there are several advantages of using foundry sands with bentonite content > 6% as the fine aggregate in flowable fill. These advantages include: (i) lower long-term strength gain (making the design of excavatable mixtures simpler and less risky), (ii) less flow loss, (iii) fewer components and fewer interactions between components that are difficult to characterize, and (iv) a larger fraction of inexpensive foundry sand being used in the mixture. The unconfined compressive strength (UCS) of flowable fills prepared with foundry sands is sensitive to the water-cement ratio (W/C), at least when the W/C spans a broad range (4–11). Mixtures with W/C < 6.5 generally will have excessive UCS, whereas a suitable UCS is generally associated with W/C > 6.5. Bentonite content does not affect the UCS systematically, but it does have an indirect effect in that foundry sands with more bentonite require more water to flow, which affects strength. The amount of water required to achieve adequate flow primarily is a function of the bentonite content of the foundry sand, to general, as the bentonite content of the foundry sand increases, the water content of the mixture should increase correspondingly. The amount of fly ash has only a modest effect on the amount of water required. The most important factor affecting flow loss is the presence of cementitious fly ash in the mixture. Flow loss can be reduced appreciably by using a foundry sand with at least 6% bentonite so that fly ash fines need not be added to the mixture.
Case History: Stabilization Of The Sugar Creek Limestone Mine Using Dry Scrubber Ash
Authors: Moberly RL , Voss LB , Mings ML
Published: April 2008

Mine stabilization with coal combustion by-products such as fly ash is common throughout the United States. However, the use of the dry scrubber ash as opposed to fly ash has created some unique challenges in permitting and monitoring. The dry scrubber ash is a mixture of fly ash and residue from a dry scrubber unit designed to control air pollutants. The dry scrubber ash contains ammonia, and ventilation during mine stabilization can become a major issue. An abandoned room and pillar limestone mine in Sugar Creek, Missouri, which is owned by Lafarge North America, Inc. (Lafarge), is being backfilled using between 100 tons (90,700 kg) and 900 (816,300 kg) tons per day of dry scrubber ash slurry generated by two nearby power plants. Mixing the dry scrubber ash with water at the site creates the slurry. The slurry is injected into the mine through 8- to 10-inch (0.2 to 0.25 rn) diameter cased boreholes drilled through as much as 175 feet (53.3 m) of soil and rock overburden. Because of previous subsidence, the Mine Safety and Health Administration (MSHA) refused permission to enter the majority of the mine and also did not allow construction equipment to be placed on top of the unstable portions of the mine. Planning and permitting for this project started in the mid 1990's. Prior to beginning injection activities, Lafarge obtained both Local and State permits for the dry scrubber ash project. The various permits required monitoring the extent of the underground areas stabilized, the progress in filling subsided areas, the volume of fly ash placed for stabilization, and potential environmental impacts (including ammonia emissions). Because of the restriction placed by MSHA on entering the majority of the mine, all observations of injection to date have been conducted via remote video photography or ultrasonic distance measuring sensor. The mine stabilization began on December 19, 2001. As of May 2003, approximately 165,000 tons (149.7 million kg) of dry scrubber ash slurry have been injected into the mine.
Thermally Insulating Foundations and Ground Slabs Using Highly-Foamed Concrete
Authors: Jones MR , Giannakou A
Published: April 2008

Foamed concrete, comprising a cementitious paste or mortar together with preformed foam, has many attractive properties, perhaps the most useful being its excellent thermal insulation properties, and therefore it can be classified as controlled thermal fill (CTF). Although widely used as a simple backfill, foamed concrete can be designed easily for particular densities (800-1600 kg/m3), flow characteristics (100–300 mm spread), strength (typically less than 10 MPa), and thermal insulation performance (0.2–0.6 W/mK). These properties make it an ideal material for house construction, in particular, for enhancing the thermal efficiency of the foundations and ground slab. This paper examines the performance of a range of foamed concretes for trench fill foundations and ground slabs in terms of thermal performance and main engineering, permeation, and durability properties. The consonant advantages of using fly ash (low-lime, fine, and coarse) technology will also be discussed.
Rising to New Challenges in Formulating for Agriculture
Authors: Lindner GJ
Published: April 2008

Today's formulator of agricultural products is barraged with a host of increasing challenges. They are faced with the need to develop more profitable differentiated products in shorter product cycles with fewer resources, and in the face of increasingly crowded patent landscapes and shifting regulatory environments. Consolidation among agricultural manufacturers is driven by financial requirements to grow market share while at the same time reduce costs to improve profitability. Unfortunately, corresponding consolidation and cost reduction has resulted in narrowing of technical focus and reduction in technical resources available for new product development so there is increasing pressure for differentiation from intense competition between fewer, larger suppliers in many markets. This focus on fewer products and the corresponding need to protect investments has concentrated the intellectual property field. Overlaid on this, regulatory issues including new rules on existing products, also apply growing pressure on formulators as threats to viability of formulae. Technologies offering higher rates of first pass success, troublefree operation, and “future proofing” against component loss offer advantages in addressing challenges. High success rate approaches feature experimental design techniques when developing robust formulations and development of differentiated products uses selection criteria that address current and anticipated needs. The needs reflect regulatory and toxicological considerations in addition to physical performance and are met by selecting low risk and broadly effective inert ingredients.
The Effect of Dispersant Solubility, Dispersant Dosage, Granule Diameter, and Dome Versus Radial Extrusion on Granule Spontaneity of Disintegration and Resistance to Attrition
Authors: Winowiski T , Lebo S , Gustafsson J
Published: April 2008

Dissolution rate of 16 sulfonated dispersants was measured in both water and 32-0-0 liquid fertilizer. Two dispersants, BNA and UCA, having different dissolution rates, were used to granulate a 70 % Amicarbazone formulation. Extrusions were made on a MG-55 Multigranulator using both the dome and radial modes with 0.8 mm and 1.0 mm screens. BNA and UCA were included at levels of 5, 10, and 15% of the formulation. The remaining 14 dispersants were compared at fixed levels of 10 % using only the 0.8 mm screen and dome mode. Premix water requirements varied according to dispersant chemistry. Granule disintegration was measured in hard water by number of inversions, ASTM E l945, and CIPAC MT-174. High level of dispersant, slow dissolution rate of dispersant, and larger diameter granules lead to reduced disintegration rate in water. In addition to these factors, disintegration in 32-0-0 was further affected by porosity of the granule.
Improved Formulations through Synergistic Combinations based on Alkyl Glucosides
Authors: Bergström K , Johansson IM
Published: April 2008

Sugar surfactants have attracted a lot of interest in the last decades, both due to technical properties as well as to the extremely favorable ecological and toxicological properties. It is well known that alcohol glucosides have excellent aqueous solubility, a low temperature dependence compared to nonionic ethoxylates, and are stable in the presence of high levels of electrolytes. Furthermore, they are compatible with anionic, cationic, and other nonionic surfactants, making them extremely suitable for formulating concentrated products in the agrochemical area. In this paper, the synergistic effect of shortchained alkyl glucosides mixed with alcohol ethoxylates or amine derivatives have been investigated. These synergies have been manifested by lowering both surface tension and cmc as well as increasing wetting properties towards hydrophobic surfaces. The model system used contained agrochemical electrolytes such as glyphosate, MCPA-DMA salt and fertilizers. The relevance of the finding is supported by the increased bio-efficacy of a mixed adjuvant seen in a greenhouse test. Furthermore, this study shows that short-chained glucosides can be used as efficient solubilizers for adjuvants or wetting agents in high electrolyte system (i.e., fertilizers, active ingredients) to avoid phase separation. The effect has been assessed by studying the influence on cloud point as well as the amount of glucoside needed to solubilizer a nonionic wetting agent into a high electrolyte solution.
Predicted Deposition Variability Due to Fluctuations in Release Height and Drop Size Distribution
Authors: Teske ME , Thistle HW , Reardon RC , Cormier G , Amirault P , Davies DC , Cameron RS , Dorr G , Hewitt AJ , Brown JR , LeClerc MY , Karipot A
Published: April 2008

An extensive field study has been undertaken to quantify the aerial release of spray material through the changes in meteorology as the day progresses. An important subset of these collected data is one-second interval data of the aircraft behavior and the mechanical release systems. These unique data provide an excellent source of information on bounding the variability in the expected deposition patterns, and how this variability might impact any error bounds established around the time-averaged predictions generated by the AGDISP model. This paper quantifies the variability in aerial application parameters and makes suggestions with regard to possible implications of this variability on the variability of deposition predictions in the flight line direction.
Comparison of Abscission Spray Application Practices for Mechanical Harvesting of Oranges
Authors: Farooq M , Salyani M , Whitney JD
Published: April 2008

Two air-carrier sprayers were used to investigate the feasibility of applying abscission materials from one side of the tree in a two-row bedded orange grove. One-sided (bed side) and two-sided (both bed and ditch side) applications at 2.4 and 4.8 km/h were compared using each sprayer. Tank mixture contained active ingredient (a.i.) 5-chloro-3-methyl-4-nitro-l-H-pyrazole (CMN-P) at about 350 mg/L a.i., a surfactant, a drift retardant, and a fluorescent tracer. Leaf samples were collected from different locations on the bed and ditch sides, and deposition was determined by fluorometry. The efficacy of abscission application was assessed in terms of fruit detachment force (FDF) and percent fruit removal (PFR) by trunk shakers.

With both sprayers, one-sided applications resulted in comparable depositions to two-sided applications at the far side of the lower canopy level. This result implies that one-sided applications might provide acceptable spray coverage in lightly foliated canopies. Abscission sprays at one-half or full a.i. (526 or 1052 g/ha) rate reduced fruit detachment force significantly. The best results were obtained with two-sided applications at lower ground speed (highest volume/a.i. rate). The air-curtain sprayer at full a.i. rate and the air-blast sprayer at one-half or full a.i. rate resulted in a significant increase in percent fruit removal.
Effect of Adjuvant on the Efficacy of Glyphosate Applied at Different Times of Day
Authors: Young BG , Young JM
Published: April 2008

Glyphosate was applied alone and with either ammonium sulfate (AMS) or RUSA 703 (a premix of hydroxypropyl guar and AMS). Herbicide treatments were applied at 3-h intervals starting at 6:00 am and ending at 9:00 pm. The efficacy of glyphosate was dependent on the application time of day for all weed species tested, except for common waterhemp in the greenhouse. In general, applications at 6:00 am and 9:00 pm resulted in the least control of all weed species. The efficacy of glyphosate was often improved with the addition of AMS when glyphosate was applied at a suboptimal time of day. RUSA 703 did not result in any benefit in glyphosate efficacy beyond AMS. The addition of RUSA 703 to glyphosate improved the efficacy of glyphosate as often as AMS in greenhouse studies, but not in field studies.
A Novel Water Conditioning Adjuvant for Use with Formulated and Nonformulated Glyphosate
Authors: Penner D , Michael J , Brown WG
Published: April 2008

Glyphosate is a weak acid, sold as the isopropylamine, ammonium, potassium, or trimethylsulfonium salt. A water conditioning adjuvant such as diammonium sulfate is commonly recommended for glyphosate application in hard water. This is especially necessary for applications to velvetleaf, which has calcium-rich leaves. There is an application preference to handle liquids rather than solids. Our goal was to identify a liquid water conditioning adjuvant with high specific activity, which is cost effective, as well as efficacious across herbicides and weed species. The specific objective of the research was to evaluate the performance characteristics of NT3 as a water conditioning adjuvant for various glyphosate formulations on several weed species. Studies were conducted in the greenhouse with supplemental lighting. Ammonium sulfate was a more effective water conditioning adjuvant than ammonium nitrate, ammonium hydroxide, or sulfuric acid for use with glyphosate on velvetleaf. The novel water conditioning adjuvant, NT, at 1 % was as effective as or more effective than ammonium sulfate at 2 % with glyphosate across various glyphosate salts and formulations and across the weed species, velvetleaf, giant foxtail, and common lambsquarters. Furthermore, it provided limited rainfastness. NT is a liquid, it has a higher specific activity than ammonium sulfate, and it is efficacious across weed species.
Analysis of Gasoline and Diesel Fuel Samples by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES), Using Pneumatic Nebulizer and Standard Spray Chamber
Authors: Onyeso CC
Published: April 2008

A method has been developed for accurate quantitative determination of additive elements and wear metals in gasoline and diesel fuel in the concentration range of 0 to 50 ppm using inductively coupled plasma atomic emission spectrometry (ICP-AES). This method requires an ICP capable of detecting metals at the 0.02 mg/kg level, and capable of linear calibration over the range of 0.05 to 20.0 mg/kg with a correlation coefficient of 0.9999 or better. No additional ICP-AES accessory or lengthy sample preparation is required. The PerkinElmer Optima 4300 has been shown to meet this requirement.
Direct Trace and Ultra-Trace Metals Determination in Crude Oil and Fractions by Inductively Coupled Plasma Mass Spectrometry
Authors: Dreyfus S , Pécheyran C , Magnier C , Prinzhofer A , Lienemann CP , Donard OFX
Published: April 2008

A method was developed to analyze direct trace and ultra-trace metal elements in crude oil nd its fractions (maltenes-asphaltenes) by ICP-MS after sample dilution in xylene. Efficient introduction of organic compounds requires addition of O2 for complete combustion of the sample; carbon deposit on cones (interface) and extraction lenses was minimized by optimization of argon to oxygen ratio in the plasma. A PFA-100 (100 μl.mn-1) MicroFlow Nebulizer and a Scott “double pass” chilled spray chamber were associated for an optimal introduction of petroleum products. The Q-ICP/MS was equipped with platinum cones to limit drifts caused by cone corrosion during an organic analysis. A standard addition method was realized for the calibration procedure in order to control the matrix effects. Method validation was completed by analyzing three certified reference materials from the National Institute for Standards and Technology (NIST). NIST 1085b, NIST 1084a, and NIST 1634c accuracies were approximately 10 %. Detection limit of ultra trace elements in xylene were at pg.g-1 level. A clean PFA filter system was developed to separate the oil fractions (maltenes and asphaltenes) by precipitation of asphaltenes (heavy fraction) in n-heptane. For optimal detection conditions, the samples were diluted in xylene according to their pre-estimated element concentration range. Total mass balance shows a recovery close to 100 % for Ni, V, Cu, Mo, Ag, Sn, Ba, and Pb. These results show that elements analyzed are highly concentrated in the asphaltenic fraction.
Determination of Sulfur Content in Crude Oil Using On-Li ne X-ray Transmission Technology
Authors: Fess S
Published: April 2008

This paper describes the function and use of X-ray Transmission (XRT) analytical instrumentation as applied to the classification and blending of crude oil that contains 0.1–3.3 % sulfur by weight. In the XRT method, sulfur absorbs X-rays transmitted between an X-ray source and detector. The technique compensates for density changes in the oil and minimizes the effects of variations in the C/H ratio of the oil. When used on-line the instrument obtains the sulfur measurement in the high- pressure flow conditions required to pump crude oil, typically 800 psig in pipelines. Automatic compensation for variations in oil density and temperature are achieved using integrated densitometer and temperature sensor readings taken by the instrument as the sulfur is being measured. In this paper calibration, precision, and long-term stability results are shown. Experimental data were obtained using a commercially available on-line XRT analyzer.
DP-SCD and LTMGC for Determination of Low Sulfur Levels in Hydrocarbons
Authors: Gras RL , Luong JC , Mustacich RV , Shearer RL
Published: April 2008

A novel measurement technique has been developed for the rapid determination of low levels of sulfur in hydrocarbon matrices. The technique employs low thermal mass gas chromatography (LTMGC) and a dual plasma sulfur chemiluminescence detector (DP-SCD). Highly sensitive total volatile sulfur measurement can be made in less than 30 s with detection limits in the 20–30 parts per billion range. Response is linear over at least three orders of magnitude sulfur with excellent repeatability. By taking advantage of LTMGC's rapid temperature programming and cool down time, it is also possible to measure individual sulfur species, analogous to ASTM D 5623. Conditions have also been developed using the same analytical apparatus to detect the major elemental sulfur allotropes (S2, S3, S6, S7, and S8) in gasoline at levels that can cause silver corrosion.
Mercury Measurements in Fossil Fuels, Particularly Petrochemicals
Authors: Stockwell PB , Corns WT , Bryce DW
Published: April 2008

The dangers of mercury and its derivatives, especially organomercury compounds have been well documented for almost half a century. Concerns remain regarding mercury contamination in aqueous ecosystems. Significant quantities of mercury are present in fossil fuels, particularly petrochemicals.

We still manage to pollute the atmosphere and environment by the use of coal and petrochemicals. The impact of mercury in natural gas has been such that there have been at least six experiences of plant failure which have been traced to corrosion due to mercury attacks on aluminium rotors in the plant fabric. Very little attention is being given to mercury removal strategies, and in order for these to be successful there is an urgent requirement to determine the speciation profile of the natural gas or liquid hydrocarbon condensates. Atomic fluorescence spectrometry is an ideal analytical technique to determine the levels of mercury both before and after removal systems. The authors will outline achievements of both laboratory and online measurement systems for this important area of research. These systems have been operating at the required levels of performance and in the case of some of the online systems, have been in place operating 24 hours per day 7 days per week for more than 2 years. This has encouraged other companies to install similar systems.
Recent Advances in Gas Chromatographic/Atomic Emission Hetero-Atom Selective Detection for Characterization of Petroleum Streams and Products
Authors: Di Sanzo FP , Diehl JW
Published: April 2008

The selective detection of organo-compounds containing hetero-atoms is used extensively in the petroleum industry for process control (sulfur, nitrogen, etc.) and additives in fuels (sulfur, nitrogen, oxygen, phosphorous, etc.). The most common selective atom detection is performed with atomic emission (AED), sulfur/nitrogen chemiluminescence (SCD, NCD), and photometric (FPD, p-FPD). Atomic emission detection has an advantage over the other selective detectors since in an automated analysis scheme several hetero-elements may be detected for rapid sample screening. This paper describes the unique capabilities of atomic emission detection of fuels and petroleum fractions using several applications. In addition, a simplified version of comprehensive GCxGC that enhances hetero-atom selectivity by significantly reducing the matrix interference from the large hydrocarbon background is coupled with a microwave induced helium plasma atomic emission detector (GCxGC/AED). The GCxGC uses simple valve based flow modulation optimized for samples with a boiling point in the gasoline and jet fuel range. The technique is useful for screening fuels additives, contaminants, etc.
Improvements in the Determination of Fluorine in Fuel and Lubricants by Oxidative Combustion and Ion-Selective Electrode Detection
Authors: Nash LJ
Published: April 2008

Oxidative combustion combined with ion-selective electrode detection is one of several techniques available for the analysis of fluorine in fuels and lubricants to the petroleum and petrochemical industry. This technique was first developed in the mid-1990s to provide an alternative to the widely used Wickbold method, which is very time consuming and extremely hazardous. The earl designs were marginally successful due to the lack of sensitivity and stability, the use of large volumes of solvents, inconsistent delivery of fluids, plugging of catch and hold valves, numerous sources of contamination, and long analysis times. The design has been refined to enhance the sensitivity, stability, and accuracy of the fluoride determination. Enhancements include improved ion-specific electrodes with increased sensitivity, the use of circulating baths to stabilize temperature fluctuations, improved sample introduction and flow systems, and redesigned electronic circuitry.
Phosphorus Additive Chemistry and Its Effects on the Phosphorus Volatility of Engine Oils
Authors: Selby TW , Bosch RJ , Fee DC
Published: April 2008

The most widely used and effective anti-wear/anti-oxidation additives in engine oil contain phosphorus that can partially volatilize during engine operation. Unfortunately, volatile phosphorus in the exhaust stream degrades the function of the exhaust catalyst in reducing air pollution. Earlier studies in a special volatility bench test using the Phosphorus Emission Index have shown that phosphorus volatility is not related to engine oil volatility or to phosphorus content in the unused engine oil. At the time, it had been speculated that this unexpected lack of correlation with initial phosphorus concentration could be explained by 1) the effects of other engine oil additives and/or 2) variations in the phosphorus additive chemistry. The first speculation was relatively recently confirmed by taxi fleet studies of catalyst degradation by phosphorus-containing oils by the Ford Motor Company. It remained to determine if differences in phosphorus additive chemistry were also a factor, and this is the subject of the present study.
Analysis of the Volatiles Generated During the Selby-Noack Test by 31P NMR Spectroscopy
Authors: Bosch RJ , Fee DC , Selby TW
Published: April 2008

A series of engine oil samples collected during a study of their Phosphorus Emission Index values were analyzed by 31P Nuclear Magnetic Resonance Spectroscopy. (The PEI analyses themselves were presented in an associated paper [1]). NMR spectra were generated to obtain and explain the mode of formation and identity of the phosphorus-containing species in the volatiles generated during the Selby-Noack volatility test and to compare these species to those found in both the fresh oil and the residual oil remaining after the volatility test.
An Assessment of Current GCL Manufacturing Quality Control and On-Site Acceptance Testing Standard of Practice
Authors: Erickson RB , Jesionek KS
Published: April 2008

The intent of establishing an ASTM standard practice for geosynthetic clay liner (GCL) manufacturing quality control (MQC) (ASTM D 5889) and a guide for construction quality assurance (CQA) (ASTM D 6495) acceptance testing requirements is to lead the industry toward a common standpoint with regard to GCL material requirements and testing. Although these methods provide the design practitioner a baseline for specifying GCL material properties and testing, the acceptance of these methods by the design community is dependent upon the intent of each design, the differences in GCL materials and the designer's exposure to GCLs.

An assessment of GCL material properties and testing outlined in the ASTM methods for MQC and CQA testing is presented. To gage the extent to which the methods have standardized the North American GCL market, the authors compare the ASTM methods to 160 GCL specifications from projects they were involved over the past year. Although approximately 70 % of the actual GCL project specifications conform to the current industry standard of practice, additional progress in promoting the ASTM methods and test designations will further standardize MQC and CQA testing whereby reducing exceptions and clarifications between GCL manufacturers and designers. From this comparison, the authors present recommended changes to the current ASTM MQC and CQA standards to bring the ASTM standards in line with current state of the practice GCL testing.
Laboratory Measurement of GCL Shear Strength
Authors: Fox PJ , Stark TD , Swan RH
Published: April 2008

This paper discusses the laboratory measurement of internal and interface shear strengths of geosynthetic clay liners (GCLs). All relevant issues are addressed, including test apparatus, gripping/clamping, hydration, consolidation, shear displacement rate, and post-test measurements. The standard 300 x 300 mm direct shear box is expected to remain the apparatus of choice for GCL strength testing. A poor gripping/clamping system may cause progressive failure of a GCL specimen, resulting in erroneous peak and large displacement shear strengths. GCL specimens should be hydrated and consolidated to match expected field hydration and loading conditions. Consolidation stresses should be applied in small increments to minimize bentonite extrusion. The appropriate displacement rate during shear is an issue of continuing debate. Available data indicate that dry encapsulated GCLs and hydrated geomembrane/needle-punched GCL interfaces can be sheared at 1 mm/min. Peak internal shear strengths of hydrated GCLs generally increase withincreasing displacement rate although some key studies have produced contradictory results. Residual internal shear strengths of hydrated GCLs may increase or remain constant with increasing displacement rate. A maximum displacement rate of 0.1 mm/min. is recommended for hydrated GCL internal shear tests until this issue is resolved. Once a test is completed, the mode of failure should be recorded and GCL water contents should be measured. Shear stress-displacement relationships should be included as part of all GCL testing reports.
Investigation of the Behavior of Geosynthetic Clay Liners Subjected to Thermal Gradients in Basal Liner Applications
Authors: Southen JM , Rowe RK
Published: April 2008

Composite liners comprised of geomembranes and geosynthetic clay liners can be an effective means of minimizing fluid flow and associated groundwater contamination from municipal solid waste landfills. There remains uncertainty, however, regarding the long-term performance of such systems under conditions of elevated temperature that may occur at the base of landfills attributable to exothermic waste degradation processes. The heat generated by these processes may lead to the development of a thermal gradient through the lining system that creates a risk of desiccation within the uppermost portion of the subsoil and the geosynthetic clay liner itself. To investigate this issue, a series of small-scale laboratory experiments were developed in an effort to simulate the hydraulic and thermal conditions existing at the base of a landfill. This paper presents the results of investigations into the influence of various parameters on the behavior of a composite liner. The distribution of temperature and water content over time is discussed, as well as potential impacts on the performance of the geosynthetic clay liner.