Ammonia (NH3) emission rates (ER) of ten commercial layer houses (six high-rise or HR houses and four manure-belt or MB houses) with different manure handling or dietary schemes were monitored for one year in Iowa (IA) and Pennsylvania (PA). Gaseous (NH3 and CO2) concentrations of incoming and exhaust air streams were measured using custom-designed portable monitoring units that shared similar performance to EPA-approved measurement apparatus. Building ventilation rates were determined by calibrated CO2 mass balance using the latest metabolic rate data for modern laying hens. The field monitoring involved a total of 386 and 164 house-day measurements or 18,528 and 7,872 30-min emission data points for the HR houses and the MB houses, respectively. The ER showed considerable diurnal and seasonal variations. The annual mean ERs (g NH3 hen-1 d-1) and standard errors were 0.90 ±0.027 for IA-HR houses with standard diet, 0.81 ±0.02 for IA-HR houses with a nutritionally balanced 1% lower crude protein diet, 0.83 ±0.070 for PA-HR houses with standard diet, 0.054 ±0.0035 for IAMB houses with daily manure removal, and 0.094 ±0.006 for PA-MB houses with twice a week manure removal. Mass balance of nitrogen (N) intake and output performed for IA-HR houses revealed a total N intake recovery of 94% to 101%, further verifying the certainty of the NH3 ER measurements. Results of the study contribute to the U.S. national inventory on NH3 emissions from animal feeding operations, particularly laying hen facilities as affected by housing type, manure handling scheme, crude protein content of the diet, and geographical location.

Twelve commercial broiler houses in the U.S. were each monitored for at least thirteen 48 h periods over the course of one year to obtain ammonia emission data. Paired repetition of houses on four farms represents current construction with variety in litter management (built-up or new litter each flock) and climate conditions (cold or mixed-humid). Ammonia concentration was determined using portable electrochemical sensors incorporating a fresh air purge cycle. Ventilation rate was determined via in-situ measurement of fan capacity, fan on-off times, and house static pressure difference. There were seasonal trends in exhaust ammonia concentration (highest in cold weather) and ventilation rates (highest in warm weather) but not for emission rate. Flocks with at least three monitoring periods (13 of 22 flocks) demonstrated similar emission rates at a given bird age among the four study farms and across the seasons. An analysis of emissions from all houses on the three farms using built-up litter resulted in predicted regression slopes of 0.028, 0.034, and 0.038 g NH3 bird-1 d-1 per day of age; the fourth farm, managed with new litter, had the lowest emission rate at 0.024 g NH3 bird-1 d-1. The intercept of these composite relationships was influenced by litter conditions, with flocks on new litter having essentially no emissions for about six days while built-up litter flocks had emissions starting at flock placement. Data from all four farms and all flocks provided a regression slope of 0.031(±0.001 std error) g NH3 bird-1 d-1 per day of age. Emission rate per animal unit for built-up litter flocks indicated very high emissions for the youngest birds (under 14 days of age), after which time the emissions decreased exponentially and were then relatively steady for the balance of the flock cycle.ABSTRACT. Twelve commercial broiler houses in the U.S. were each monitored for at least thirteen 48 h periods over the course of one year to obtain ammonia emission data. Paired repetition of houses on four farms represents current construction with variety in litter management (built-up or new litter each flock) and climate conditions (cold or mixed-humid). Ammonia concentration was determined using portable electrochemical sensors incorporating a fresh air purge cycle. Ventilation rate was determined via in-situ measurement of fan capacity, fan on-off times, and house static pressure difference. There were seasonal trends in exhaust ammonia concentration (highest in cold weather) and ventilation rates (highest in warm weather) but not for emission rate. Flocks with at least three monitoring periods (13 of 22 flocks) demonstrated similar emission rates at a given bird age among the four study farms and across the seasons. An analysis of emissions from all houses on the three farms using built-up litter resulted in predicted regression slopes of 0.028, 0.034, and 0.038 g NH 3 bird −1 d −1 per day of age; the fourth farm, managed with new litter, had the lowest emission rate at 0.024 g NH 3 bird −1 d −1 . The intercept of the...

The structure and ordering conditions of the self-assembled monolayers (SAMs) of HS(EO)xR, where R ) CH3, EO ) CH2CH2O, and x ) 3-6, on polycrystalline gold (Au) were determined by reflectionabsorption infrared spectroscopy (RAIRS), spectroscopic ellipsometry (SE), and electrochemical impedance spectroscopy (EIS). For x ) 5 and 6, RAIRS and SE data show that the 1-thiaoligo(ethylene oxide) [TOEO] segments adopt the highly ordered helical structure of the folded-chain crystal polymorph of crystalline poly(ethylene oxide) and are oriented normal to the substrate. RAIRS and SE data obtained as a function of immersion time show that x ) 6 attains the highly ordered, all helical conformation faster than x ) 5. For x ) 3 and 4, RAIRS and SE data indicate largely disordered structures, with some all-trans conformation but little evidence of the helical conformation. EIS measurements, in an aqueous environment, indicate a significant presence of water in all SAMs with x < 6 while x ) 6 remains essentially free of water and/or ions for extensive periods (2 h). These data suggest that a minimum of five ethylene oxide units are necessary for TOEO SAMs to adopt the helical conformation and that SAMs with x < 6 are penetrated by water or ionic species in an aqueous environment, regardless of the order of the TOEO segment in air.

Current ASAE standards of heat and moisture production (HP, MP) for swine are primarily based on data collected nearly four decades ago. Feedstuffs, management practices, growth rate, and lean percentage of swine have changed HP and MP considerably in that time period. Literature data shows that lean percent increased 1.55% in the last 10 years, resulting in an increase in HP by approximately 15%. Data were compiled into two categories: prior to 1988, and 1988 to present. Analysis of this data revealed that HP increased 12.4% to 35.3% between the two categories, with the largest differences occurring at higher temperatures. The results also revealed lack of HP and MP data for greater than 90 kg pigs. The HP and MP standards for design of swine housing systems should be updated.

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A series of extremely uniform prototype reference cantilevers has been created that can be used to calibrate the spring constants of atomic force microscopy (AFM) cantilevers and other micromechanical structures. By utilizing optimal combinations of material, design and the latest microfabrication processing techniques, arrays of cantilevers were created from single crystal (1 0 0) silicon. Nominal spring constants were estimated to be in the range 0.02 N m −1 to 0.2 N m −1. Resonance frequency measurements were used to assess the uniformity of devices from different portions of a silicon-on-insulator wafer and in different processing batches. Variations of less than 1% (relative standard deviation) in resonance frequency attested to the high degree of uniformity achieved. Independent calibration of cantilevers in an array using an electrostatic force balance indicated that the actual spring constants ranged from 0.0260 N m −1 ± 0.0005 N m −1 (±1.9%) to 0.2099 N m −1 ± 0.0009 N m −1 (±0.43%). The results confirm the feasibility of creating uniform reference cantilevers and calibrating them using a Système International d'Unités (SI)-traceable technique, making these devices excellent candidates as force calibration standards for AFM.

The self-assembled monolayers (SAMs) of a series of octadecyl 1-thiaoligo(ethylene oxide)x disulfides {[S(CH2CH2O)xC18H37]2}, where x ) 4-8, were assembled on gold and characterized by reflection-absorption infrared spectroscopy (RAIRS), spectroscopic ellipsometry (SE), electrochemical impedance spectroscopy (EIS), synchrotron X-ray reflectivity (XRR), and atomic force microscopy (AFM). For x ) 6-8, the EIS data indicate stable, highly ordered, nearly defect-free SAMs that behave as ideal capacitors in an electrochemical environment, comparable to well-packed SAMs of octadecanethiol. For these SAMs, the RAIRS data show that the 1-thiaoligo(ethylene oxide) (TOEO) segments, oriented normal to the substrate, adopt the ordered 7 /2 helical conformation of the folded-chain crystal polymorph of poly(ethylene oxide) (PEO) and the hydrocarbon segments, tilted ∼30°to the normal, adopt a nearly all-trans conformation. AFM measurements on x ) 6 yield reciprocal lattice points that are consistent with the 3 × 3R30°overlayer structure commonly found in SAMs of long-chain alkanethiols. Within the limits of our measurements, the x ) 6-8 SAMs appear to be isostructural. As a result, SAM thicknesses should increase in a predictable fashion. SE and XRR measurements indicate thickness increases of 0.30 ( 0.05 nm/ethylene oxide (EO) unit, in good agreement with the expected increase of ∼0.28 nm/EO unit as derived from the unit cell dimensions of crystalline PEO. Films in which relative thicknesses can be calculated directly from crystallographic dimensions and are independent of refractive index should be useful materials for surface science metrology.

A method for calibrating the stiffness of atomic force microscope (AFM) cantilevers is demonstrated using an array of uniform microfabricated reference cantilevers. A series of force-displacement curves was obtained using a commercial AFM test cantilever on the reference cantilever array, and the data were analyzed using an implied Euler-Bernoulli model to extract the test cantilever spring constant from linear regression fitting. The method offers a factor of 5 improvement over the precision of the usual reference cantilever calibration method and, when combined with the Systeme International traceability potential of the cantilever array, can provide very accurate spring constant calibrations.