bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Major, Minor, and Trace Elements in Human Serum by Using Inductively Coupled Plasma-Atomic Emission Spectroscopy
Authors: Mianzhi Zhuang , Barnes Ramon M.
Published: June 2005

An evaluation of two methods of sample preparation for human serum and two methods of calibration for inductively coupled plasma spectroscopy is made statistically for 10 elements. Digestion of 1 mL of serum in nitric-perchloric acids was found to be more reliable than a 10-fold dilution of the sample. With acid digestion, aqueous calibration standards are sufficient and standard addition is unnecessary. Only Ca, Na, Mg, P, and Sr can be determined reliably with the dilution approach. The relative standard deviations ranged between 0.7 and 6% for ICP-AES analysis with 0.75 mL sample injections.
On the Determination of Oxygen in Organic Solvents Using an Inductively Coupled Plasma
Authors: Hauser Peter Ch. , Blades M. W.
Published: June 2005

The application of an inductively coupled plasma spectrometer, equipped with a linear photodiode array detector, to the determination of total oxygen in compounds dissolved in xylene has been investigated. Sample introduction was achieved with the use of a concentric nebulizer, and nonresonant, near-infrared emission lines were used for detection. A torch that prevents the entrainment of atmospheric oxygen and that is not susceptible to the buildup of carbon deposits was developed for this application. It was found that the measured emission intensity is dependent on both the concentration of oxygen and the boiling point of the oxygen-containing compound that is dissolved in the xylene. The detection limit for oxygen determination was found to be 0.070% total oxygen.
Correlation-Based Data Processing for an Inductively Coupled Plasma/Fourier Transform Spectrometer System
Authors: Ng R. C. L. , Horlick Gary
Published: June 2005

A simple cross-correlation technique is presented for processing interferograms generated by an ultraviolet-visible Fourier transform spectrometer coupled to an inductively coupled plasma. Interferograms resulting from the emission of samples in the ICP can be automatically interrogated for the presence or absence of up to 70 elements, and automatic qualitative analysis is possible, complete with an assessment of spectral overlaps. In concept, the cross-correlation method amounts to “software slew-scanning” as it provides one with an a posteriori method to study and select the spectral information about the sample as measured with the FTS-ICP system. This represents a unique spectrochemical measurement capability compared with current dispersive-based, direct-reading, and slew-scanning spectrometers as applied to ICP emission spectrometry.
Optical Artifacts in Circularly Polarized Luminescence Spectroscopy
Authors: Dekkers Harry P. J. M. , Moraal Perry F. , Timper James M. , Riehl James P.
Published: June 2005

The source of optical artifacts in circularly polarized luminescence is examined by application of the method of Mueller matrices. Expressions for the circularly polarized luminescence intensity are developed that illustrate that the source of the artifact in most cases is due to the small inherent birefringence in the photoelastic modulator employed in the experimental measurement. Experimental results are presented that are consistent with this conclusion.
Rheo-Optical Fourier Transform Infrared Spectroscopy of Polymers. 10: Strain-Induced Crystallization of Sulfur-Crosslinked Natural Rubber during Cyclic Deformation
Authors: Siesler H. W.
Published: June 2005

Simultaneous Fourier transform infrared and stress-strain measurements have been applied to monitor the onset, progress, and decay of strain-induced crystallization during cyclic loading-unloading of sulfur-crosslinked natural rubber. The investigations also provided data in terms of the orientation of the average polymer and the polymer chains in the strain-induced crystal phase.
The Influence of Temperature on Absorbance in Graphite Furnace Atomic Absorption Spectrometry. I: General Considerations
Authors: Lovett R. J.
Published: June 2005

The influence of a temperature ramp on the absorbance in graphite furnace atomic spectroscopy has been investigated with the use of a computer simulation of the absorption process. For increasing temperature, the absorbance will increase for low values of the damping constant at constant pressure and all values of the damping constant at constant volume. For large values of the damping constant at constant pressure (the presumed real situation), the absorbance decreases with increasing temperature due to the narrowing of the collisional profile. Hyperfine structure diminishes the change in absorbance within limits. The evaluation of the number density of analyte for temperatures (times) other than the peak maximum temperature could be in error if the peak maximum absorbance of a GFAAS peak is used to derive the number densities at the other temperatures. In effect, the relative absorbances on the peak in GFAAS are not totally representative of the relative atom release and removal peak. The presence of multiple ground states can, under certain circumstances, improve the absorbance-atom density relationship between the peak maximum absorbance and other absorbances on the peak. The temperature ramp has no deleterious effect on the analytical capabilities of GFAAS when the effect of temperature on absorbance is considered.
Identification and Determination of Oxygen-Containing Inorganosulfur Compounds by Laser Raman Spectrometry
Authors: Sato Soei , Higuchi Seiichiro , Tanaka Shigeyuki
Published: June 2005

A new method for the analysis of oxygen-containing inorganosulfur compounds was developed utilizing laser Raman spectrometry. The Raman spectra in the 1400–200 cmcm−1 region was observed for nine different oxygen-containing inorganosulfur compounds dissolved in aqueous solutions and in the solid states. The Raman spectra of these compounds exhibited the characteristic spectral features for oxygen-sulfur inorganic compounds. The relation between the Raman frequencies and the chemical structures of the compounds is discussed in terms of characteristic group frequencies analysis and structural parameters. A table of these characteristic Raman bands and the quantitative aspects for the determination for some of these compounds in aqueous solution are also reported. With the use of the thiocyanate ion as an internal standard, the relation between the peak intensities and concentrations of the compounds exhibited good linearity. It is also found that simultaneous determination of several different compounds is possible. The laser Raman spectroscopic method is shown to be very useful for the structural analysis, identification, and determination of these compounds in solid states and in aqueous solutions.
The Rapid Identification of Bacteria Using Time-Resolved Fluorescence and Fluorescence Excitation Spectral Methods
Authors: Brahma S. K. , Baek M. P. , Gaskill D. , Force R. K. , Nelson W. H. , Sperry J.
Published: June 2005

Time-resolved fluorescence spectra have been obtained for Escherichia coli, Pseudomonas fluorescens, Staphylococcus epidermidis, and Enterobacter cloacae. Pseudomonas fluorescens has been shown to have distinctly different time-resolved spectra. Fluorescence excitation spectra for the three other organisms showing similar time-resolved spectra are very nearly alike, while spectra of Pseudomonas fluorescens are markedly different. This suggests that the changes in the average fluorescence lifetime with emission wavelength are due to the separate contributions from fluorophores of distinctly different lifetimes which have emission maxima at different wavelengths.
Subsurface Layer Detection by Fourier Transform Infrared Photoacoustic Spectroscopy
Authors: Teramae N. , Tanaka S.
Published: June 2005

Fourier transform infrared photoacoustic spectroscopy was applied to the nondestructive detection of subsurface layer of bilayered films. Spectral separation of the subsurface layer was carried out by the application of the subtraction technique to the photoacoustic amplitude spectra of bilayered films whose top layer has various values in thickness. As a result, it was found that the spectrum corresponding to the subsurface layer could be separated, and that the photoacoustic depth profiling was possible as far as the depth, which is approximately half the value of the thermal diffusion length.
FT-IR Studies of the Low-Temperature-Induced Chemical Changes in Rawhide Coal
Authors: Gethner J. S.
Published: June 2005

Control of the water in the porous structure of coal is desirable both in reaction studies and in order that one be able to rationally compare the composition and processing behavior of different coals. Experimental studies of coal routinely use coal which has been dried under standard conditions (frequently vacuumed at approximately 100°C). It is generally accepted that such drying produces little or no significant chemical or structural change other than volatilization of the water. Recently developed in-situ FT-IR difference spectroscopy techniques, which are extremely sensitive to chemical changes, are used to examine the effect of 100°C vacuum drying on Rawhide (subbituminous) coal. Complex spectroscopic changes of the coal are found to occur which might be indicative of changes both in internal hydrogen-bonded interactions in the coal and in the number and types of strong “crosslinking” bonds. Reactions involving carbon-oxygen functionality, probably as carboxylic acid groups, are observed. A significant change is observed in the composition of the acidic functionality contained in the coal. The substantial IR absorptivity changes in both static and kinetic experiments imply that significant perturbation of the organic coal matrix takes place upon drying. These data imply that mechanistic interpretations of low-temperature chemistry may not be correct. While it is quite conceivable that low-temperature thermal chemistry might not affect the behavior of coal in a much higher temperature pyrolysis, liquefaction or gasification procedure, it is likely to influence the results of some analytical procedures and interpretation of coal structural studies, low-temperature oxidation studies, and low-temperature degradation chemistry. Standardized drying procedures in any particular laboratory might have unknowingly changed the coal structure. Thus, the anomalous results of subsequent experiments could not be fully interpreted because the thermal history of the sample was altered.
Analysis of Two Spectral Lines with a Multichannel System or by Measuring n(2)(T): Comparison of Errors
Authors: Rebolledo M. A. , González F.
Published: June 2005

In this paper we have studied the errors involved in the analysis of two spectral lines with a photon-counting multichannel system. These errors are compared with those obtained from the measurement of the second-order factorial moment, n(2) ( T), for a single value of T.
A Fourier Transform Spectrometer for UV and Visible Measurements of Atomic Emission Sources
Authors: Stubley E. A. , Horlick G.
Published: June 2005

A versatile Michelson interferometer system capable of Fourier transform spectrochemical measurements from the UV to the infrared has been developed in our laboratory. Laser fringe referencing is used in the interferometer system to sequence digitization, and interferograms are signal averaged under white-light interferogram control. Interferograms are acquired and transformed with a PDP-11 minicomputer. Interfacing between the interferometer and the PDP-11 is accomplished with the use of a 6502-based-microprocessor-controlled system. Modifications to the interferometer system are described and its application to atomic spectrochemical measurements at wavelengths as short as 200 nm is briefly illustrated.
Laser Fluorescence Detection in Microcolumn Liquid Chromatography: Application to Derivatized Carboxylic Acids
Authors: McGuffin V. L. , Zare R. N.
Published: June 2005

A laser-induced fluorescence (LIF) detector is evaluated for use with high-efficiency liquid chromatography columns of capillary dimensions. This detector employs a cw helium-cadmium laser (325 nm, 5–10 mW) as the excitation source, together with a fused-silica capillary flowcell and filter/photomultiplier optical system. The flowcell, which is an integral part of the microcolumn, contributes from 0.06 nL2 to 0.06 µL2 variance to the chromatographic system for capillaries of 35 to 330 µm diameter, respectively. The LIF detector is capable of sensing femtogram amounts of coumarin 440, and the response is linearly related to concentration over at least eight orders of magnitude. The potential of this combination of analytical techniques is demonstrated through the analysis of multicomponent mixtures of derivatized fatty acids and prostaglandins at the pico- and subpicomole level.
A Real-Time Correlation-Based Data Processing System for Interferometric Signals
Authors: Ng R. C. L. , Horlick Gary
Published: June 2005

A relatively simple dedicated hardware processor is described that allows the real-time processing of interferogram signals as generated by a Fourier transform spectrometer. The heart of the processing system is a multiplier-accumulator chip. With this chip and a small support microcomputer, interferograms can be processed with the use of cross-correlation techniques. Application of the system to the processing of interferograms from an atomic emission source in the ultraviolet is briefly illustrated.
On the Problems of CD Spectropolarimeters. II: Artifacts in CD Spectrometers
Authors: Shindo Yohji , Nakagawa Masayuki , Ohmi Yasuhiro
Published: June 2005

The Mueller matrix approach is used to investigate the artifacts resulting from the coupling of anisotropic samples and imperfect hardwares of commercially available CD spectropolarimeters. On the basis of the results obtained, attention is called to the instrumental limitation of CD spectropolarimeters in the study of CD phenomena of systems with macroscopic anisotropy. Furthermore, strong doubts are presented about what is called an induced CD spectrum observed in an achiral anisotropic medium.
A Dual-Channel, Fiber-Optic-Coupled Direct Reader with Gated Integration for Transient Radiation Measurements
Authors: Swan J. M. , Sacks R. D.
Published: June 2005

A dual-channel, fiber-optic-coupled direct reader attachment for a spectrometer is described which uses bundles of 200-μm diameter quartz optical fibers as spectrometer exit slits and as a means of isolating the photomultiplier tubes from the region of the radiation source. The band-pass of the fiber exit slits is reduced by the coating of the fiber ends with an opaque Al film, leaving a 75-μm-wide clear region. The ends of the fibers are located in the focal plane of the spectrometer, with a fixed bundle positioned to correspond to the wavelength readout of the spectrometer and the other bundle adjustable on the focal plane to provide a simultaneous background correction at an adjacent wavelength. A dual-channel time-gated integrator based on an Evans 4130 integrator board is used with the fiber-optic-coupled photoelectric detector to obtain background-corrected, time-gated radiation measurements on transient, nonrepetitive radiation sources. Preparation techniques and optical properties of the quartz optical fiber bundles are discussed. Amplifier and timing circuits for the gated integrator are presented. Electrical and analytical performance data for the system are presented with the use of the high-intensity radiation pulse from an electrically vaporized thin-film plasma source.
Laser-Excited Atomic Fluorescence of Some Precious Metals in the Air/Acetylene Flame
Authors: Kachin S. V. , Smith B. W. , Winefordner J. D.
Published: June 2005

A pulsed, tunable dye laser pumped with a nitrogen laser is used to excite the atomic fluorescence of Ru, Pd, Ir, Pt, and Au in an air/acetylene flame. The detection limits obtained have been improved about 40 to 400 times, excepting those for Au. These elements can be detected at the ng/mL (ppb) level or less with analytical curve linearity of over four orders of magnitude. Improvement of the detection limits was achieved mainly by the use of a large-aperture detection system and a frequency-doubled dye laser for excitation of nonresonance atomic fluorescence. Interferences among these five elements and also from Rh, Os, Co, Cu, and Ni were investigated. The detection limits obtained are superior to flame atomic absorption spectrometry and flame atomic emission spectrometry and comparable to or better than the best detection limits of atomic emission inductively coupled plasma spectrometry and dc plasma spectrometry. Of course, the spectral selectivity greatly exceeds other analytical atomic spectroscopic methods.
Molecular Spectrometry with a Holographically Scanned cw Dye Laser and Supersonic Cooling
Authors: Whitten W. B. , Ramsey J. M.
Published: June 2005

The application of a high-resolution self-scanning cw dye laser to molecular spectrometry is explored. The laser uses optical feedback from a holographic pattern in a BaTiO3 crystal to control its frequency and linewidth. Fluorescence excitation spectra of molecular iodine in a supersonic expansion have been measured, demonstrating the potential of the new technique.
An Environmental Chamber for FT-IR Measurements of Thin Films on Smooth Metals
Authors: Saperstein David D.
Published: June 2005

A design of a cell to record IR spectra of monolayers on low area metals at elevated or reduced temperature and/or pressure is described. Its utility is illustrated with spectra of Langmuir-Blodgett monolayers of cadmium arachidate under nonambient conditions.
Polarized FT-IR Spectra of Benzene and Anthracene Oriented in a Nematic Liquid Crystal Solvent
Authors: Sedman Jacqueline , Butler Ian S.
Published: June 2005

Polarized FT-IR spectra have been obtained for benzene and anthracene oriented in a nematic liquid crystal solvent (Merck 1132) and allow vibrational symmetry assignments to be proposed for those fundamentals detected in the mid-IR region of the dichroic spectra. The symmetry assignments proposed for anthracene are in excellent agreement with those from earlier, technically more difficult, single-crystal IR transmission measurements.
Enhancement of Raman Spectra Obtained at Low Signal-To-Noise Ratios: Matched Filtering and Adaptive Peak Detection
Authors: Dyer Stephen A. , Hardin David S.
Published: June 2005

Two methods of Raman spectral peak enhancement are described. The matched-filter approach employs an optimal filter to maximize the signal-to-noise ratio at its output. The impulse response of the matched filter is the reversed version of the profile of the spectral peak to be enhanced; therefore, the effectiveness of the matched filter depends on a priori knowledge of the peak's shape. The adaptive peak detector (APD) utilizes a filter having a time-varying impulse response. APD performance is relatively insensitive to peak shape, but is instead contingent on a number of user-specified parameters. Background is provided to acquaint the reader with signal processing terminology, and practical guidelines are given for computationally inexpensive computer implementations of both techniques. Examples are shown which demonstrate the effects of these two enhancement methods on simulated Raman spectra.
Multiplicative Scatter Correction of Visible Reflectance Spectra in Color Determination of Meat Surfaces
Authors: Iversen Arve J. , Palm Torgny
Published: June 2005

Due to inhomogenous surfaces, differences in light scatter and a variable fat-to-meat ratio in the limited area hit by the incident light beam, the instrumentally evaluated color parameters of dry sausage exhibited unacceptable high standard deviations. Color parameters from cut surfaces were evaluated from reflectance spectra in the region 380–760 nm, measured by a scanning spectrophotometer fitted with an intergrating sphere. The spectra were transformed to the C.I.E. 1976 L*a*b* color system. Twenty-nine replicates were examined, and although it was impossible to differentiate them visually, even at different light conditions, the L*a*b* values ranged by as much as 7, 3.3, and 2.8 units, respectively. The MSC transformation compensates linearly for both additive and multiplicative optical effects in the data. It alters neither the mean reflectance spectrum nor the mean color values, but it reduces variations between replicates considerably. As expected, the SD in lightness, L*, was most affected, with a decrease by a factor 5.2, while the SD in redness-greenness, a*, and blueness-yellowness, b*, decreased by factors 2.3 and 1.7, respectively.
Infrared Studies of 2-Isopropenyl-2-Oxazoline Copolymers
Authors: Nyquist R. A. , Schuetz J. E.
Published: June 2005

An increase in the tensile strength of BA/MMA/AA/IPO copolymer cured latex film is attributed to the amide-ester cross-linkages formed by chemical reaction of AA and IPO units between latex particles. Amide-ester formation in this copolymer is not a linear function of temperature. Cross-linking between latex particles causes decreased mobility of remaining AA and IPO units, and further heating is required in order for the copolymer to again become fluid enough so that remaining AA and IPO units can react to form amide-ester linkages. An IR method is given for the quantitative analysis of SIPO copolymers.
Raman Spectroscopy in Trace Analysis for Phenols in Water
Authors: Marley Nancy A. , Mann Charles K. , Vickers Thomas J.
Published: June 2005

Data are reported for the determination of 2-, 3-, and 4-nitrophenols in water by Raman spectroscopy. Simultaneous multicomponent determination is shown to be possible with the use of correlation and least-squares data treatments. Detection limits of 0.03, 0.4, 0.07, and 0.2 mg/L are reported for 2-nitro-, 3-nitro-, 4-nitro-, and 2-chloro-4-nitro-phenol, respectively, with the use of the 458-nm line of an argon-ion laser. The potential for ultraviolet resonance enhancement in the determination of phenols has been examined with the use of the 337.1-nm line of a nitrogen laser. Enhancement results are reported for phenol and eight substituted phenols.
Zirconium Coprecipitation for Simultaneous Multielement Determination of Trace Metals in Seawater by Inductively Coupled Plasma Atomic Emission Spectrometry
Authors: Akagi Tasuku , Nojiri Yukihiro , Matsui Masahiro , Haraguchi Hiroki
Published: June 2005

Zirconium coprecipitation for simultaneous multielement determination of trace metals in seawater has been examined by inductively coupled plasma atomic emission spectrometry. Optimum pH conditions and other experimental procedures for coprecipitation were investigated in order that the method for multielement preconcentration could be evaluated. The concentration factor of 20 times the original concentration was obtained, although it was limited by spectral interference with zirconium. The present coprecipitation method improves the detection limits and other analytical figures of merit for 17 trace metals (Al, As, Cd, Co, Cr, Cu, Fe, La, Mn, Mo, Ni, Pb, Sb, Ti, V, Y, and Zn), which were estimated by the use of artificial seawater samples, and it was applied to natural seawater analysis.
Advanced Algorithm for Determining Component Spectra Based on Principal Component Analysis
Authors: Kawata S. , Komeda H. , Sasaki K. , Minami S.
Published: June 2005

A method is proposed for determining the component spectra from a set of unknown two-component mixture spectra. This method is considered as an advanced version of the Lawton-Sylvestre self-modeling curve resolution. The disadvantage of the weakness against noise is overcome by the introduction of the concept of filtering; the uncertainty of the solution is removed by the reduction of the band for each curve to a single curve with aid of the concept of entropy minimization. Experimental results with infrared absorption spectra of xylene isomer mixtures and visible absorption spectra of dye mixtures demonstrate the power of this method.
Fourier Transform Infrared Spectrometry Using a Very-Long-Pathlength Cell: Dioxygen Difluoride Stability and Reactions with Plutonium Compounds
Authors: Kim K. C. , Campbell G. M.
Published: June 2005

A unique spectroscopic device combining a Fourier transform infrared spectrometry instrument and a very-long-pathlength cell (a few hundred meters) is described. It shows much promise for spectroscopic studies of unstable or transient species at extremely low concentrations in a temperature-controlled environment. Results are presented of dioxygen difluoride (O2F2) fluorination reactions with Pu compounds and of O2F2 thermal stability measurements in the cell.
A Fourier Transform Diode Array Spectrometer for the UV, Visible, and Near-IR
Authors: Aryamanya-Mugisha Henry , Williams Ronald R.
Published: June 2005

A new Fourier transform spectrometer for the ultraviolet, visible, and near-infrared regions is described. Based on a Michelson interferometer with a tilted rather than moving mirror, the new spectrometer produces interferograms which are spatial (instead of temporal) intensity patterns and uses photodiode array detection. The primary advantages of the new spectrometer are optical and mechanical simplicity and extremely fast spectral acquisition, as well as large optical throughput. In addition, it is shown that shot noise does not dominate in the recorded interferogram and so Fellgett's advantage applies to the transformed spectrum.
Comparative Complexity of Emission Spectra from ICP, dc Arc, and Spark Excitation Sources
Authors: Winge R. K. , DeKalb E. L. , Fassel V. A.
Published: June 2005

A comparison of atomic emission spectra excited in high voltage spark and dc arc discharges and in an inductively coupled plasma revealed that the most complex spectra were emitted by the high voltage spark. The dc arc and the inductively coupled plasma yielded spectra of approximately equivalent complexity. These observations are not in accord with the impressions conveyed in the literature.
Some Industrial Applications of FT-IR Diffuse Reflectance Spectroscopy
Authors: Chalmers J. M. , Mackenzie M. W.
Published: June 2005

The technique of diffuse reflectance infrared spectroscopy can be used to characterize materials without recourse to extensive sample preparation. The applicability of this sampling approach is demonstrated on a variety of diffusely scattering solids including bulk powders and foams. The technique is also applied to the identification of chromatographically (HPLC and TLC) separated fractions.
Critical Aspects of Measurement of Circular and Linear Dichroism: A Device for Absolute Calibration
Authors: Norden Bengt , Seth Stefan
Published: June 2005

The polarization effect of one or several tilted, parallel air-spaced fused silica plates is calculated. It is generally necessary to include higher order reflections. A device consisting of 1–4 plates tilted 10–45° from normal incidence is proposed for the calibration of differential linear dichroism (LD) in the measurement ranges 10−3 to 10−1 decadic absorbance units and the wavelength region 200–700 nm. The experimental LD measured in these ranges on commercial circular dichrometers, converted to LD mode according to Norden and Davidsson, was in excellent agreement with the calculated, nonempirical results. Since the response function of the instrument in this conversion mode is the same for LD and CD, the method also provides a means for absolute calibration of CD. The results can also be applied to polarized scattering and fluorescence. (For previous papers on this theme, see Refs. 6, 9 and 12.)
Optimization of Precision and Accuracy in X-Ray Fluorescence Analysis of Silicate Rocks
Authors: Bower Nathan W.
Published: June 2005

The precision of XRF measurements on a Rigaku 3064 has been determined for 10 major and 12 trace elements in 10 geochemical reference rocks. A complete procedure for evaluating the sources of imprecision in XRF analyses is presented with new equations and data demonstrating that for many measurements a minute is an adequate count time for obtaining the minimum error (1% RSD) in an analysis. Longer analysis times were found to be limited by sample preparation errors, and for very long analysis times, the precision is predicted to get worse.
ESTIMATING COTTON LEAF AREA INDEX NONDESTRUCTIVELY WITH A LIGHT SENSOR
Authors: Tewolde H. , Sistani K. R. , Rowe D. E. , Adeli A. , Tsegaye T.
Published: June 2005

AccuPAR, which is a relatively new instrument for estimating leaf area index (LAI) by measuring light interception, has wide distribution but only limited independent evaluation of its accuracy. The objective of this study was to evaluate the accuracy of AccuPAR for estimating LAI of cotton (Gossypium hirsutum L.) planted on different row spacings. Cotton LAI was measured nondestructively with AccuPAR and destructively by taking plant samples three to four times during each growing season in 2002 and 2003 on research conducted at three locations in Mississippi, USA. The results suggested that meter accuracy was affected by differences between row spacing and the length of the light‐sensing segment of the meter. Supplemental tests showed that meter accuracy improved with meter placement, which eliminated length differences and with near solar noon measurements, which minimized row‐to‐row shading overlap. We conclude that the meter can more accurately estimate row crop LAI when the under‐canopy placement of the meter and the time of measurement are selected so that the light‐sensing segment of the meter captures shading of an entire row cross‐section and that row‐to‐row shading overlap is eliminated or minimized.
Association between Septoria tritici Blotch, Plant Height, and Heading Date in Wheat
Authors: Simón María Rosa , Perelló Analía E. , Cordo Cristina A. , Larrán Silvina , van der Putten Peter E. L. , Struik Paul C.
Published: June 2005

The relationship between resistance to Septoria tritici blotch with plant height and heading date has been in most cases attributed to genetic associations. More efficient selection for higher levels of quantitative resistance may result if the nature of the association between susceptibility with earliness and shortness can be determined. Genetic resistance to Septoria tritici blotch and its relationships with plant height and heading date were recorded in 50 Argentinean wheat (Triticum aestivum L.) cultivars in three environments (two in the field and one in the greenhouse) with one virulent isolate of Mycosphaerella graminicola (Fuckel) Schroeter, in Cohn (anamorph Septoria tritici Rob. ex Desm.). Furthermore, a set of 16 cultivars was tested with seven isolates of M. graminicola in the greenhouse at the adult stage. Cultivars varied greatly in resistance to the disease and plant material was identified with moderate to high levels of resistance to several isolates. The field and greenhouse experiments demonstrated no evidence of genetic associations between plant height, heading date, and resistance, indicating that selection of early and short lines with high levels of quantitative resistance is possible. The relationships between those traits were mainly caused by environmental and epidemiological factors, which indicates that management of cultivars should be optimized to minimize these associations.
Spatial Analysis of Precision Agriculture Treatments in Randomized Complete Blocks: Guidelines for Covariance Model Selection
Authors: Hong Nan , White Jeffrey G. , Gumpertz Marcia L. , Weisz Randy
Published: June 2005

Failure to account for spatially correlated errors when present in the classical randomized complete block (RCB) analysis may cause inefficient estimation of treatment significance. Covariance model selection is a necessary component for spatial adjustment to estimate treatment significance. We discuss methods for selecting a covariance model in RCB analyses in the presence of spatial correlation and demonstrate one procedure in detail. The procedure uses three models: the randomized complete block with independent and identically distributed errors (RCBiid), RCB with correlated errors, and models with correlated errors but no block effects. The semivariogram of the residuals from fitting a model with just fixed effects, the likelihood ratio test, and Akaike Information Criterion are used for model selection. To illustrate the procedure, we analyzed winter wheat (Triticum aestivum L.) forage and corn (Zea mays L.) grain yield in the presence of spatial heterogeneity within blocks from a site‐specific N management study. We compared the selected covariance models to the RCBiid models and to other spatial models with respect to the estimation of treatment significance. The procedure can be extended to any experiment with fixed effects, or with both fixed and random effects, and which may potentially have spatially correlated errors. The procedure is systematic and readily implemented; however, it remains difficult to evaluate whether an adequate covariance model has been selected.
Effects of Biomass Accumulation on the Playing Quality of a Kentucky Bluegrass Stabilizer System Used for Sports Fields
Authors: Sherratt P. J. , Street J. R. , Gardner D. S.
Published: June 2005

Sand‐based sports fields can deteriorate rapidly under intense sports traffic due to poor surface stability. Natural grass stabilizer systems have been developed as one option to improve sand‐based field stability and therefore provide a more consistent playing surface. Accumulation of biomass above the stabilizer system may form a layer between the grass plants and the stabilizer that causes the grass to shear off under sports traffic. A study was established in August 2000 at The Ohio State University to evaluate aeration, verticutting, and topdressing practices that may reduce biomass accumulation on a stabilizer system. The study examined playability characteristics of the stabilizer system and the relationship between biomass accumulation and playing quality by measuring traction, divot resistance, surface hardness, and ball rebound. The stabilizer had no effect on traction at 12.7‐mm depth but did increase traction at 18.8‐ and 31.3‐mm depths where shearing and physical displacement of underlying soil can occur on sand rootzones. The stabilizer increased divot resistance. Biomass accumulation reduced both traction at 18.8‐ and 31.3‐mm stabilizer profile depths and divot resistance. Biomass management on stabilizer carpet is thus necessary for long‐term performance. Sand topdressing increased biomass depth while verticutting reduced biomass depth. Verticutting one time per month increased divot resistance. Verticutting, however, increased both surface hardness and ball rebound. Solid tining reduced surface hardness but resulted in stabilizer deterioration. Thus, verticutting programs could be adopted to manage biomass accumulation on natural grass stabilizers. However, research into the prevention of biomass accumulation on sand‐based stabilized sports fields needs further investigation.
Defining Yield‐Based Management Zones for Corn‐Soybean Rotations
Authors: Brock A. , Brouder S. M. , Blumhoff G. , Hofmann B. S.
Published: June 2005

Unsupervised clustering has been proposed for developing georeferenced agronomic information into management zones (MZs). Our objectives were to use fuzzy c‐means clustering to identify yield‐based MZs, and to compare spatial association and agreement among corn (Zea mays L.) yield‐based (CYB) MZs, soybean [Glycine max (L.) Merr.] yield‐based (SYB) MZs, and published soil survey map units. Six years of yield monitor data (three per species) from four fields were used with the clustering software MZ Analyst. Clustering success was evaluated with four performance measures. Two measures of variance reduction and the fuzziness performance index (FPI) indicated clustering optimization with 4 to 6 MZs. In contrast, the normalized classification entropy (NCE) indicated that yield data were optimally organized with only 2 MZs. On average, the 4‐MZ delineation reduced the yield variance to 40% of the whole field variance (corn within CYB MZs and soybean within SYB MZs); mean relative yields within MZs were significantly different from each other, ranging from 23% below to 12% above the whole‐field mean. With 4 MZs, CYB and SYB MZs were significantly associated in all fields, but weighted agreement between CYB and SYB MZs was only slight (0.06 ≤ Kw ≤ 0.34), indicating crop‐specificity in MZ delineation. In general, highest yielding MZs were significantly associated with areas mapped as a poorly drained, level soil series while lower yielding MZs corresponded to map units for eroded or more slopping soils. However, clustering yields by soil series reduced yield variance less than unsupervised, yield‐based clustering. Routine application of MZ Analyst likely requires more decision support for identifying clustering success.
Corn Response to Late‐Spring Nitrogen Management in the Walnut Creek Watershed
Authors: Karlen Douglas L. , Dinnes Dana L. , Jaynes Dan B. , Hurburgh Charles R. , Cambardella Cynthia A. , Colvin Thomas S. , Rippke Glen R.
Published: June 2005

A 400‐ha subbasin study within the Walnut Creek watershed near Ames, IA, confirmed that using late‐spring soil nitrate nitrogen (NO3–N) test (LSNT) fertilizer recommendations could significantly reduce NO3–N loss in drainage water, but detailed crop response was not reported. Herein we summarize corn (Zea mays L.) response to the LSNT program when implemented across the Clarion–Nicollet–Webster soil association. The LSNT was used to determine the recommended N fertilizer rate that was applied uniformly across each field except on check strips where zero or nonlimiting (>220 kg N ha−1) sidedress N was applied. Leaf chlorophyll (SPAD) readings, end‐of‐season stalk nitrate concentrations, and grain yield and quality (protein, starch, and oil content) showed significant year, field, soil map unit and N rate response. Average grain yield with the LSNT program was significantly lower than the nonlimiting rate in 1997 and 1998 but not in 1999 or 2000. This suggests that although watershed‐scale implementation of the LSNT can reduce nitrate loss through drainage water, it may also increase producer risk, especially when above‐normal rainfall occurs shortly after the sidedress N fertilizer is applied. To encourage adoption of the LSNT program for its water quality benefits, we suggest that federal, state, or private agencies develop affordable risk insurance or some other financial incentives to help producers minimize the potential crop risk associated with this program.
DIALLEL‐SAS05: A Comprehensive Program for Griffing's and Gardner–Eberhart Analyses
Authors: Zhang Yudong , Kang Manjit S. , Lamkey Kendall R.
Published: June 2005

Diallel mating designs provide to breeders useful genetic information, such as general combining ability (GCA) and specific combining ability (SCA), to help them devise appropriate breeding and selection strategies. Here we report a much‐improved version of DIALLEL‐SAS that was originally released in 1997. The new program, DIALLEL–SAS05, has a clear and user‐friendly interface that was designed to meet users’ needs for various diallel‐cross design experiments. DIALLEL‐SAS05 has major advantages over DIALLEL‐SAS in that: (i) it analyzes not only all four Griffing's diallel methods (both fixed and random models), but it also computes Gardner–Eberhart's Analyses II and III; (ii) it provides desired results from diallel experiments with parent number from 4 to 12, (iii) it can analyze diallel data from any number of environments, and (iv) for a random‐effects model, it provides estimates of GCA (σ2g) and SCA (σ2s) variances, which can be used to estimate additive (σ2A) and dominance (σ2D) variances, and ultimately narrow‐sense heritability (h2). DIALLEL‐SAS05 also provides information on GCA × ENV, SCA × ENV, reciprocal × ENV, maternal × ENV, and nonmaternal × ENV interactions, when applicable. DIALLEL‐SAS05 should greatly improve researchers’ efficiency in analyzing and interpreting diallel‐cross data. The program code is available on a CD from the corresponding author.
Theoretical Analysis of Soil and Plant Traits Influencing Daily Plant Water Flux on Drying Soils
Authors: Sinclair Thomas R.
Published: June 2005

Experimental evidence has been accumulating for a number of years that daily transpiration rates respond to the progressive drying of soil in a similar manner across a wide range of conditions when expressed as a function of available volumetric soil water content. There is little decrease in gas exchange until only about one‐third of the available soil water remains in the soil, and then gas exchange decreases in a nearly linear manner until the available soil water is exhausted. There exists no theoretical derivation that explicitly provides a basis for explaining the consistency in this response observed over a wide range of conditions. A relatively simple derivation is presented by defining plant water flux on drying soil relative to a plant on well‐watered soil and by examining the response in the relevant range of soil volumetric water content. This derivation resulted in a relatively simple expression that predicted daily transpiration rate response to drying soil that was consistent with experimental observations. Further, the results of this analysis showed the response was essentially independent of root length density, transpiration rate, and soil depth. Also, large decreases in soil hydraulic conductivity as the soil dries had only modest influences on the daily transpiration rate response. Expression of relative transpiration as a function of volumetric soil water content available to support transpiration also minimized the influence of soil texture on the overall response of water flux to drying soil. The derivation offers a theoretical basis to explain the stability in daily transpiration response to drying soil that has been observed over a wide range of conditions.
Ultra‐High Plant Populations and Nitrogen Fertility Effects on Corn in the Mississippi Valley
Authors: Bruns H. Arnold , Abbas H. K.
Published: June 2005

Populations for high yield and low mycotoxin levels in furrow‐irrigated corn (Zea mays L.) have yet to be firmly established for the Midsouth USA. Preplant N applications compared with a split application and the effects on yield, yield components, and mycotoxin levels were also examined. Experiments were conducted at Site WR (102‐cm‐wide rows, Beulah fine sandy loam) and Site NR (76‐cm‐wide rows, Dundee silty clay). Plant densities of 71760, 82160, 92560, and 102960 plants ha−1 were grown in eight‐row plots, 9.1 m long at both sites. The N fertility treatments were 112 kg N ha−1 preplant, 224 kg N ha−1 preplant, and 112 kg N ha−1 preplant + 112 kg N ha−1 sidedressed at V6 (six leaves). Yields at Site WR did not differ among populations. Maximum yields at Site NR were at 71760 plants ha−1 (10.3 Mg ha−1) and then declined (b = −0.5065). Kernels per ear declined (b = −40.09 and b = −42.69), kernel weights declined (b = −0.4328 and b = −0.8172), and stalk lodging increased (b = 0.0103 and b = 0.0251) with increased populations for Sites WR and NR, respectively. These and previous data place the maximum population for corn in the Midsouth at about 70000 plants ha−1. No differences in yield occurred between the 224 kg N ha−1 preplant treatment and the split application of N. Yields were generally less with 112 kg N ha−1 per‐plant only. Aflatoxin and fumonisin levels at both sites were unaffected by plant population of N fertility.
Botanical Composition and Forage Production in an Emulated Silvopasture
Authors: Buergler Alicia L. , Fike John H. , Burger James A. , Feldhake Charles R. , McKenna James A. , Teutsch Chris D.
Published: June 2005

Integrating trees into pasture may increase pasture production and improve nutritive value by altering both species composition and productivity. Our objective was to determine forage yield and botanical composition in response to tree species, tree density, and slope position in an emulated silvopasture (the site had no animals). In 1995, black walnut (Juglans nigra L.) and honey locust (Gleditisia triacanthos L.) trees were planted within plots (r = 3) of predominantly tall fescue (Festuca arundinacea Schreb.) pasture. Trees were planted down slopes in rows to create low, medium, and high tree densities at shoulder‐, mid‐, and toe‐slope positions. Sampling sites (n = 54) under field treatment combinations were harvested May to October at 35‐d intervals in 2002 and 2003. Before spring, summer, and fall harvests, plots were subsampled for botanical composition. Tree species did not affect botanical composition when compared over the two seasons. Plots under honey locust trees tended to have more fescue in a dry year (2002) and more legumes and less dead herbage in a wet year (2003). Greater percentages of warm‐season grasses and fewer weeds were observed at low tree density sites in 2003. Forage mass (5280, 6130, and 4970 kg ha−1 at low, medium, and high tree densities) was 16% greater under medium‐density trees. Plots under black walnut yielded 13% more forage than those under honey locust (5790 vs. 5130 kg ha−1). Appropriately spaced trees have potential to positively alter botanical composition and can support greater forage production in a southern Appalachian silvopasture.
Hydrochemistry of rivers in an acid sulphate soil hotspot area in western Finland
Authors: ROOS M. , ÅSTRÖM M.
Published: June 2005

During heavy rains and snow melting, acid sulphate (AS) soils on the coastal plains of Finland are flushed resulting in discharge of acidic and metal-rich waters that strongly affect small streams. In this study, the impact of AS soils occurrence and hydrological changes on water quality were determined for 21 rivers (catchment sizes between 964122 km2) running through an AS soil hotspot area in western central Finland. Water samples, collected at the outlet, during eight selected events, were analysed for pH, dissolved organic carbon, electrical conductivity (EC) and 32 chemical elements. Based on the correlation with percentage arable land in the catchments (a rough estimate of AS soil occurrences, as up to 50% of the arable land is underlain with these soils), it was possible to categorize variables into those that are enriched in runoff from such land, depleted in runoff from such land (only one element), and not affected by land-use type in the catchments. Of the variables enriched in runoff from arable land, some were leached from AS soils during high-water flows, in particular (aluminium, boron, beryllium, cadmium, cobalt, copper, lithium, manganese, nickel, sulphur, silicon, thorium, thallium, uranium, and zinc) and others occurred in highest concentrations during lower flows (calcium, EC, potassium, magnesium, sodium, rubidium and strontium). Molybdenum and phosphorus were not leached from AS soils in larger amounts than from other soils and thus related to other factors connected to the arable land. Based on the concentrations of potentially toxic metals derived from AS soils, the 21 rivers were ranked from the least (Lestijoki River, Lapväärtinjoki River and Perhonjoki River) to the most (Sulvanjoki River, Vöyrinjoki River and Maalahdenjoki River) heavily AS soil impacted. It has been decided that Vöyrinjoki is to be dredged along a ca. 20 km distance. This is quite alarming considering the high metal concentrations in the river.;