bluuebunny/crossref_metadata_2025 huggingface dataset:
A study on the injection characteristics of a liquid-phase liquefied petroleum gas injector for air-fuel ratio control
Authors: Sim Hansub , Lee Kangyoon , Chung Namhoon , Sunwoo Myoungho
Published: June 2005

Liquefied petroleum gas (LPG) is widely used as a gaseous fuel in spark ignition engines because of its considerable advantages over gasoline. However, the LPG engine suffers a torque loss because the vapour-phase LPG displaces a larger volume of air than do gasoline droplets. In order to improve engine power as well as fuel consumption and air-fuel ratio control, considerable research has been devoted to improving the LPG injection system. In the liquid-phase LPG injection systems, the injection rate of an injector is affected by the fuel temperature, injection pressure, and driving voltage. When injection conditions change, the air-fuel ratio should be accurately controlled in order to reduce exhaust emissions. In this study, correction factors for the fuel injection rate are developed on the basis of fuel temperature, injection pressure, and injector driving voltage. A compensation method to control the amount of injected fuel is proposed for a liquid-phase LPG injection control system. The experimental results show that the liquid-phase LPG injection system works well over the entire range of engine speeds and load conditions, and the air-fuel ratio can be accurately controlled by using the proposed compensation algorithm.
Phototriggered Chemical Reduction of NADP+ by Zn-reconstituted Myoglobin and Triethanolamine as a Sacrificial Donor
Authors: Nishiyama Katsuhiko , Mie Yasuhiro , Kishita Midori , Yamada Chiho , Kitagawa Rumiko , Taniguchi Isao
Published: June 2005

The phototriggered chemical reduction of NADP+ was accomplished in the dark by photoirradiated zinc protoporphyrin-reconstituted myoglobin (Zn–Mb) and triethanolamine (TEA) as a sacrificial donor. The reduction efficiency of NADP+ in the dark depended strongly on the concentration of TEA and the duration of photoirradiation.
Microwave-assisted One-pot Synthesis of α-Amino Phosphonates via Three Component Coupling on a Silica Gel Support
Authors: Zhan Zhuang-Ping , Yang Rui-Feng , Li Jun-Ping
Published: June 2005

A fast, highly efficient, general procedure under microwave irradiation, using silica gel-supported reagents for the synthesis of α-aminophosphonates is developed through a one-pot reaction of aldehydes and ketones with amines.
Fabrication and Characterization of Nanostructurally Flowerlike Aggregates of TiO2 via a Surfactant-free Solution Route: Effect of Various Reaction Media
Authors: Yang Songwang , Gao Lian
Published: June 2005

Flowerlike submicrometer-scaled aggregates assembled with nanorod structures have been successfully fabricated via a simple surfactant-free solution process. The fabricated nanostructures exhibit high photocatalytic activity in the photodegradation of aqueous Methylene Blue solution.
Highly Ruffled Manganese(III) Complexes of meso-Tetra(tert-butyl)porphyrin
Authors: Ikezaki Akira , Nakamura Mikio
Published: June 2005

Extraordinarily ruffled acetato[5,10,15,20-tetra(tert-butyl)porphinato]manganese(III) has been prepared. The 1H NMR spectra have revealed that the inversion barrier of the porphyrin ring exceeds 66 kJ mol−1 and that the spin densities are quite different between the diastereotopic β-carbon atoms.
Markers of oxidative damage, antioxidant status and clinical outcome in critically ill patients
Authors: Mishra Vinita , Baines Malcolm , Wenstone Richard , Shenkin Alan
Published: June 2005

Background: Oxidative stress is a consequence of critical illness, and may have an impact on survival. We studied markers of oxidative damage and antioxidant (AO) protection and compared them with clinical scores and outcome.

Methods: Blood sampling and clinical scoring was carried out on 60 consecutively admitted intensive therapy unit (ITU) patients within 24 h of admission and then every three days of ITU stay. The patients included 30 surgical and 30 medical patients, of whom 46 survived their stay in ITU. Clinical scoring was by Acute Physiology and Chronic Health Evaluation (APACHE) II score, multiple organ dysfunction (MOD) score and sepsis rating. Oxidative damage was assessed by measurement of plasma malondialdehyde (MDA) and F2 isoprostanes (F2 IsoPs). AO protection was assessed by measurement of plasma total AO status, AO gap, ascorbic acid and the enzymes glutathione peroxidase and superoxide dismutase.

Results: Both clinical markers, APACHE II and MOD, and oxidative damage markers MDA and F2 IsoPs were significantly higher in non-survivors (NS) than in survivors (S) at the time of admission. Median (interquartile ranges) were (APACHE II), 14[12-17] (S), 20.5[16.7-22.2] (NS), P<0.0001; (MOD), 3.0[2.0-5.0] (S), 8.0[4.7-9.2] (NS), P<0.0005; (MDA, µmol/L), 0.22[0.19-0.27] (S), 0.25[0.20-0.34] (NS), P=0.04 and (F2 IsoPs, pg/mL), 9.7[6.0-9.9] (S), 11.0[9.0-12.0] (NS), P=0.01. Oxidative damage markers reduced (improved) in the survivors but increased in the non-survivors. There was little difference between the groups in AO protection markers. There was a significant positive correlation between MOD and markers of oxidative damage at the time of admission ( r=0.40, P=0.003, F2 IsoPs; r=0.28, P=0.035, MDA) and between the oxidative damage markers themselves ( r=0.32, P=0.017).

Conclusion: Increased oxidative stress is associated with poor outcome in critically ill patients, and may be a prognostic indicator. Oxidative damage markers are more useful than AO protection markers in predicting outcome.
Can opportunistic case-finding of paraproteins be clinically justified?
Authors: Beetham Robert , Howie Neil , Soutar Richard
Published: June 2005

The addition of serum protein electrophoresis by laboratory staff upon finding an increased total protein or globulin appears to be practised widely in the UK. The criteria for assessing which samples are subject to electrophoresis vary considerably. They consist of initial objective laboratory data subsequently modified, somewhat subjectively, by other laboratory data and clinical details, but have often been chosen pragmatically. The aim of the practice is to identify patients with occult B-cell malignancies that warrant treatment. While it has been lent legitimacy in many cases by involving clinical haematologists in discussions, the views of other stakeholders, including other physicians and patients, have often not been considered, thus raising a number of ethical questions that need to be addressed.

The practice is reviewed against both current knowledge of B-cell malignancies and monoclonal gammopathy of undetermined significance and criteria for screening, of which this forms a particular example. The arguments for and against addition of electrophoresis are finely balanced, partly because of the very limited outcome data available.

We conclude that those currently following this practice should continue to do so, there is a need to establish outcome data as widely as possible according to standard criteria and there should be involvement of physicians, patients and national bodies in discussions about the practice so that the practical and ethical issues can be addressed.
The effects of green tea ingestion over four weeks on atherosclerotic markers
Authors: Sung Heungsup , Min Won-Ki , Lee Woochang , Chun Sail , Park Hyosoon , Lee Yong-Wha , Jang Seongsoo , Lee Do-Hoon
Published: June 2005

Background: The objective of this study was to evaluate the effects of green tea ingestion over four weeks on atherosclerotic biological markers.

Methods: After a one-week baseline period, 12 healthy male volunteers aged 28-42 years drank 600 mL of green tea dailyfor four weeks. Lipid profile, oxidized low-density lipoprotein (ox-LDL), total antioxidant capacity (TAC), C-reactive protein (CRP) and soluble cell adhesion molecules were measured at baseline and after two and four weeks ingestion of green tea.

Results: There was no significantchange in the concentrations of lipid profile, TAC, CRP, soluble intercellular adhesion molecule-1 (sICAM-1), or soluble E-selectin after ingestion of green tea. The levels of ox-LDL and soluble vascular cell adhesion molecule-1 (sVCAM-1) were significantly decreased after four weeks of green tea ingestion (Wilcoxon signed rank test, P=0.006).

Conclusions: The results of this study suggest an in vivo anti-oxidative effect for green tea and an influence of green tea on atherosclerotic biological markers. The effect of green tea seen on ox-LDL and sVCAM-1provides a potential mechanism for the cardiovascular benefits of regular ingestion of green tea.
A simple precipitation method for measuring sialic acid in apolipoprotein B-containing lipoproteins in plasma
Authors: Shishino Koji , Yoshioka Yuki , Hashimoto Kaori , Ochi Masaaki , Aono Kenji , Murase Mitsuharu , Osawa Haruhiko , Makino Hideichi , Saheki Shuichi
Published: June 2005

Background: A convenient method for the measurement of sialic acid in plasma apoB-containing lipoproteins is described.

Methods: Dextran sulphate-Mg2+ precipitation and enzymatic sialic acid assay were combined and applied to analysis of plasma from 96 healthy controls and 136 hyperlipidaemic subjects of types IIa ( n=46), IIb ( n=43), and IV ( n=47).

Results: The sialic acid concentrations (mean±SD) in plasma apoB-containing lipoproteins were 19.4±5.9, 24.3±4.7 ( P<0.0001 versus normal), 23.0±4.7 ( P<0.0001), 27.9±5.2 ( P<0.0001), and 22.3±3.4 mg/L ( P<0.002), for normal, all types of hyperlipidaemia, types IIa, IIb, and IV, respectively. The contents of sialic acid in apoB were 2.03±0.41%, 2.09±0.35% (no significance versus normal), 1.86±0.27% ( P<0.0001), 1.97±0.26% ( P<0.02), and 2.28±0.41% ( P<0.002), for normal, all types of hyperlipidaemia, types IIa, IIb, and IV, respectively.

Conclusion: The content of sialic acid in apoB decreased significantly in type IIa but increased in type IV hyperlipidaemia, which may reflect the presence of sialic acid in very low-density lipoprotein apolipoproteins other than apoB. This simple precipitation method will be useful to evaluate the sialic acid content in low-density lipoprotein in hyperlipidaemic subjects, especially of type IIa.
Replacement of immunoassay by LC tandem mass spectrometry for the routine measurement of drugs of abuse in oral fluid
Authors: Allen KR , Azad R , Field HP , Blake DK
Published: June 2005

Background: There is increasing interest in the use of oral fluid as the matrix for the detection of drugs of abuse which requires the use of sensitive immunoassays to achieve the low detection limits required. The use of liquid chromatography linked to tandem mass spectrometry (LC/MS/MS) is explored as a possible replacement for immunoassay in screening for drugs of abuse in oral fluid samples.

Methods: Oral fluid samples collected from 72 subjects attending an addiction clinic were screened for opiates, cocaine, methadone and benzodiazepines using both enzyme-linked immunosorbent assays (ELISA) and LC/MS/MS. The latter analysis used a short gradient elution with individual drugs detected by multiple reaction monitoring using tandem mass spectrometry. Results between the two methods were compared qualitatively using the cut-off concentrations defined by the ELISA assays.

Results: With regard to the ELISA assays which show group specificity, LC/MS/ MS detected the presence of 6-monoacetylmorphine, morphine or dihydrocodeine in all but two of 49 samples positive for opiates. Of 55 samples positive for benzodiazepines by ELISA, all but two were confirmed by LC/MS/MS. Overall, LC/MS/MS compared favourably with ELISA for detection of specific drugs or their metabolites in the case of morphine, methadone and the cocaine metabolite benzoylecgonine. Many of the discrepant results between the two assays were a result of samples with drug concentrations near to the cut-off concentrations and the imprecision of these assays at very low concentrations.

Conclusion: LC/MS/MS offers a more flexible, specific and sensitive alternative to the screening of oral fluid samples for drugs of abuse than ELISA. A wide range of drugs and metabolites can be detected from a single sample injection.
Curve Fitting of Heterodyne Data
Authors: Reddy B. R.
Published: June 2005

The least-squares curve fitting procedure of experimental data is described for heterodyne detection. Two independent methods, the Maximum Likelihood method of Fisher and SIMPLEX, have been tried. The relative merits and limitations are discussed in detail.
Statistical Evaluation of an Inductively Coupled Plasma Atomic Emission Spectrometric Method for Routine Water Quality Testing
Authors: Garbarino J. R. , Jones B. E. , Stein G. P. , Belser W. T. , Taylor H. E.
Published: June 2005

In an interlaboratory test, inductively coupled plasma atomic emission spectrometry (ICP-AES) was compared with flame atomic absorption spectrometry and molecular absorption spectrophotometry for the determination of 17 major and trace elements in 100 filtered natural water samples. No unacceptable biases were detected. The analysis precision of ICP-AES was found to be equal to or better than alternative methods. Known-addition recovery experiments demonstrated that the ICP-AES determinations are accurate to between ±2 and ±10 percent; four-fifths of the tests yielded average recoveries of 95–105 percent, with an average relative standard deviation of about 5 percent.
Lens and Wedge Absorption Cells for FT-IR Spectroscopy
Authors: Hirschfeld Tomas
Published: June 2005

New cell geometries for extending the dynamic range of FT-IR absorption spectroscopy are described. These are variants of the stepped multiple thickness cells described before, in which the cell thickness varies continuously with location. Either homogeneous wedge or lenslike cells are used. The resulting distortion of the cell's photometric linearity can be straightened out computationally. However, the change in the measured energy levels drastically increases the dynamic range of the measurement for a given tolerable relative error in absorbance. The theoretical behavior of the cells is analyzed, and their photometric distortion and dynamic range calculated. The experimental realization of one of them is used to show the usefulness and limitations of the procedure.
An Introduction to Time-Resolved Pump/Probe Spectroscopy
Authors: Lytle F. E. , Parrish R. M. , Barnes W. T.
Published: June 2005

The construction and operating principles of a two-color pump/probe spectrometer are described. This instrument is capable of obtaining ground-state absorption spectra, both singlet-singlet and triplet-triplet excited-state absorption spectra, photoproduct spectra, and stimulated fluorescence spectra. In addition, time-dependent measurements can be made with an impulse response of 250 ps and a free temporal range of 13 ns.
Lifetime Measurements of Metastable Levels of Thallium and Lead in the Air-Acetylene Flame by Laser-Enhanced Ionization Spectrometry
Authors: Omenetto N. , Berthoud T. , Cavalli P. , Rossi G.
Published: June 2005

Laser-enhanced ionization spectrometry with two-step excitation has been used to evaluate the collisional lifetime of the metastable P levels of thallium and lead in an air-acetylene flame burning at atmospheric pressure and supported by a three-slot burner head fitted on a conventional nebulizing chamber. A water-cooled molybdenum electrode immersed in the flame was maintained at high negative potential with respect to the burner body. The ionization current resulting after the two-step excitation was amplified and measured with a digital storage oscilloscope and a boxcar averager. The two excimer lasers were triggered externally with two trigger pulses, one being delayed in time with respect to the other one. In this way the second laser photon, tuned at a transition starting from the metatable level under study, could be correspondingly delayed from the first photon tuned at a transition starting from the ground state. The lifetimes measured were found to be 81 ns and 360 ns for T1 and Pb, respectively.
Physical Interpretation of the Orientation Phenomenon of the Small Molecules in a Polymeric Matrix (Model of Polarizability)
Authors: Konwerska-Hrabowska Joanna
Published: June 2005

The linear UV dichroism was studied for 18 compounds encased in stretched polyethylene (PE) films and analyzed to establish the main physical factor responsible for molecular orientation. When the “shape-model” and “polarizability-model” were compared, it was found that polarizability is a more important factor than the shape of molecules. The specific relative orientation between small molecules and polymer chains is determined by the minimum in the interaction energy, i.e., the balance of repulsive and attractive forces.
A Method for Determining the Optical Properties of Materials with Respect to Thermal Radiation and Radiation from a Number of other Sources
Authors: Stay B. J. , Chalmers J. M. , Mackenzie M. W. , Mosely D. R.
Published: June 2005

A method for determining the optical properties (transmittance, reflectance, absorptance) with respect to thermal infrared radiation, and by extension of radiation from a number of other sources, is described and demonstrated by application to polymer films. A procedure for operation of the method on a Perkin Elmer 3600 Data Station interfaced to a Perkin Elmer 580B infrared spectrophotometer is described.
Triplet State Processes in Aqueous Colloidal Dispersions of Polycyclic Aromatic Hydrocarbons at Room Temperature
Authors: Weinberger Robert , Love L. J. Cline
Published: June 2005

A unique and facile means of producing room-temperature phosphorescence (RTP) from colloidal or microcrystalline suspensions of aromatic molecules in aqueous media is reported. Unlike previously reported RTP techniques, colloidal RTP is insensitive to quenching by dissolved oxygen. Delayed fluorescence was observed from several non-phosphorescent species. Potential uses of the technique are for the determination of the solubility of highly insoluble compounds and the ability to distinguish between suspended and dissolved matter.
Deconvolution in the Frequency Domain
Authors: Friesen W. I. , Michaelian K. H.
Published: June 2005

The Finite Impulse Response Operator (FIRO) method for improving the resolution of bands in a frequency-domain spectrum, developed recently by Jones and Shimokoshi (Applied Spectroscopy 37, 59 (1983)), is discussed in detail and its relationship to the analogous method of Kauppinen et al. (Applied Spectroscopy 35, 271 (1981), is shown. Under-, self-, and over-deconvolution are discussed for simulated and experimental spectra. Deconvolution of instrumentally broadened bands is discussed and implemented for the v1, Raman band of CC14; use of a Gauss-Lorentz lineshape gives the best results for this band. General guidelines for application of the FIRO method are also given.
Optimization of Sample Absorbance for Quantitative Analysis in the Presence of Pathlength Error in the IR and NIR Regions
Authors: Hirschfeld T. , Honigs D. , Hieftje G.
Published: June 2005

Optimal absorbance levels for quantitative analysis in the presence of photometric error have been described in the past. In newer instrumentation, such as FT-IR and NIRA spectrometers, the photometric error is no longer limiting. In these instruments, pathlength error due to cell or sampling irreproducibility is often a major concern. One can derive optimal absorbance by taking both pathlength and photometric errors into account. This paper analyzes the cases of pathlength error > photometric error (trivial) and various cases in which the pathlength errors and the photometric error are of the same order: adjustable concentration (trivial until dilution errors are considered), constant relative pathlength error (trivial), and constant absolute pathlength error. The latter, in particular, is analyzed in detail to give the behavior of the error, the behavior of the optimal absorbance in its presence, and the total error levels attainable.
Background Correction in Raman Spectroscopic Determination of Dimethylsulfone, Sulfate, and Bisulfate
Authors: Ling Yong-Chien , Vickers Thomas J. , Mann Charles K.
Published: June 2005

A study has been made to compare the effectiveness of thirteen methods of spectroscopic background correction in quantitative measurements. These include digital filters, least-squares fitting, and cross-correlation, as well as peak area and height measurements. Simulated data sets with varying S/N and degrees of background curvature were used. The results were compared with the results of corresponding treatments of Raman spectra of dimethyl sulfone, sulfate, and bisulfate. The range of variation of the simulated sets was greater than was possible with the experimental data, but where conditions were comparable, the agreement between them was good. This supports the conclusion that the simulations were valid. Best results were obtained by a least-squares fit with the use of simple polynomials to generate the background correction. Under the conditions employed, limits of detection were about 80 ppm for dimethyl sulfone and sulfate and 420 ppm for bisulfate.
Analytical Characteristics of the Microwave-Induced Nitrogen Discharge at Atmospheric Pressure (MINDAP)
Authors: Deutsch R. D. , Keilsohn J. P. , Hieftje G. M.
Published: June 2005

A microwave-induced plasma (MIP) is sustained at atmospheric pressure with the use of nitrogen as the plasma and nebulizer gas. The plasma is operated at 2450 MHz and has been optimized at 250 W of rf power with a total nitrogen flow rate of 1.78 L/min. The analytical performance of this plasma has been evaluated and compared with other atmospheric pressure plasma systems. Detection limits were typically in the part-per-billion concentration range, and calibration curves were linear over three-to-five orders of magnitude. Interelement interferences were observed but were overcome with the use of releasing agents. Precision for an analytical measurement was generally better than 2°/o relative standard deviation.
Further Developments in the Methodology of Surface Analysis by FT-IR: Quantitative Aspects of Diffuse Reflectance Methods
Authors: McKenzie M. T. , Koenig J. L.
Published: June 2005

The quantitative aspects of diffuse reflectance FT-IR are explored for standard E-glass/AAPS ( N-2-aminoethyl-3-aminopropyltrimethoxysilane) treated samples. Nondestructive sample preparation procedures are used. One generates calibration curves by plotting the normalized integrated intensity of the coupling agent bands in the 2990–2800 and 1700–1500 cm−1 regions vs. the concentration of the treatment solution. The data are derived by DRIFT spectroscopy, and the above results are plotted for the overlayer technique as well as for no overlayer. The scatter in the quantitative data due to fiber orientation effects has been measured and is found to be significant (20–30%). However, averaging over several orientations of the fibers results in a linear dependence of the integrated intensities of the coupling agent bands on solution concentration. The well-known breakpoint that has been observed for other coupling agent systems does not appear in the curve derived from the averaged spectra. The above-mentioned scatter is eliminated by the use of KBr overlayers on the samples. Linear calibration curves relating band intensity to concentration can be constructed. When the overlayer procedure is used, breakpoints do occur in the calibration curves. The position of these breakpoints agrees well with observations for the similar coupling agent γ-APS.
The Measurement of On-The-Fly Fourier Transform Infrared Reference Spectra of Environmentally Important Compounds
Authors: Gurka Donald F. , Umaña Mirtha , Pellizzari E. D. , Moseley Arthur , De Haseth James A.
Published: June 2005

The United States Environmental Protection Agency (U.S. EPA) requires reference spectra to support its gas chromatography/Fourier transform infrared (GC/FT-IR) routine environmental monitoring program. Although on-the-fly (OTF) techniques are needed to satisfy the Agency's high sample throughput requirements, the FT-IR vapor-phase reference spectra produced by the Agency thus far have been measured under static conditions. Accordingly, the OTF spectra of 47 environmentally important compounds have been measured by packed-column GC/FT-IR under carefully controlled conditions. The compounds selected for spectral measurement are currently regulated by the U.S. EPA and generally represent compound classes which are absent, or poorly represented, in the current U.S. EPA data base (e.g., organochlorine and organophosphorus pesticides). Where feasible, the Co-blentz Society guidelines for the measurement and recording of vapor-phase infrared reference spectra and supporting data were followed. The sensitivity order of the reference compounds as determined by the strongest spectral band and the quantity of compound injected on-column was, organophosphorus and thio-organophosphorous > aliphatic organochlorine ≥ polynuclear aromatic.
Photoacoustic Investigations of Thermally Thin Sublimates
Authors: Holter A. , Perkampus H.-H.
Published: June 2005

Photoacoustic investigations of thermally thin copper phthalocyanine sublimates on quartz were made in wide optical absorption range to verify the validity of the Rosencwaig-Gersho (RG) theory. As could be shown experimentally, both the dependence of the photoacoustic signal on the modulation frequency as well as the constancy of the photoacoustic phase angle spectra agree very well with the theoretical predictions of the RG theory. An additional exponential damping factor has to be taken into account, however, when describing the normalized photoaoustic signal as a function of the absorbance. The influence of the photoacoustic saturation effect on the normalized photoacoustic spectra is discussed.
Interferometric Detection of Near-Infrared Nonmetal Atomic Emission from a Microwave-Induced Plasma
Authors: Freeman J. E. , Hieftje G. M.
Published: June 2005

A feasibility study has coupled a helium microwave-induced plasma (MIP) and a commercial Fourier transform infrared spectrometer for nonmetal determination. In the He MIP, compounds containing nonmetal atoms are fragmented and the resulting atoms excited. Strong nonmetal emission from such elements as C, N, and O then appears on a weak, relatively unstructured plasma background in the near-infrared region (800–2000 nm). Results are sufficiently promising that continuing studies are suggested, involving both dispersive and multiplex spectrometers.
The Structure of Hexane Soot I: Spectroscopic Studies
Authors: Akhter M. S. , Chughtai A. R. , Smith D. M.
Published: June 2005

Soot produced from the combustion of fossil fuels, widely distributed in the atmosphere, is significantly different from most carbons for which the surface structure and/or reactivity have been studied. The composition and surface structure of soot derived from the combustion of n-hexane have been examined by FT-IR, Raman, UC CP/MAS NMR, and EPR spectroscopies as well as through desorption measurements. Carbon-oxygen functionalities on the fresh carbon surface include acid anhydride, a carbonyl conjugated with an aromatic segment, an alkyl-ketone, and aryl ether linkages. Also present, confirmed by isotopic substitution, is a quantity of unsaturated C-H, dependent upon the combustion conditions. The degree of aromaticity and the graphitic nature of this soot have been determined.
Fundamental Detection Limits in Spectrophotometric Analysis
Authors: Harris T. D. , Williams A. M.
Published: June 2005

Recently developed methods for measuring small absorbances have potential application in trace element spectrophotometry. Achievement of low detection limits requires compatibility between the chemical systems and the instrumental characteristics. The factors that determine compatibility are examined systematically and a new basis for comparing sensitivity is derived. The comparison is shown to be superior to the Sandell sensitivity factor for this new instrumentation. This new sensitivity factor leads to guidelines for the selection of useful chemical systems for trace analysis.
Phase Behaviors of Saturation Transfer ESR Signals at High Microwave Fields
Authors: Shimoyama Y. , Watari H.
Published: June 2005

The phase behavior of saturation transfer electron spin resonance (ST-ESR) was studied with the use of the second harmonic absorption ( V2) spectrum of the spin label (2,2,6,6-tetramethylpiperidine-1-oxyl) in glycerol-water solution. Upon application of an intense microwave field (0.508 G), a pronounced nonzero component was observed at the modulation phase where the peak-to-peak amplitude is expected to be zero. This component is the saturation transfer spectrum which is latent at the phases giving intense V2 signals. A single intergration of these obtained spectra yields a significant integrated value which varies in a sinusoidal manner. The phase discrepancy was found to be 70 degrees between the variations of the peak-to-peak amplitude and the integrated value.
A Nanosecond Photon-Counting Fluorimetric System Using a Modified Multichannel Vernier Chronotron
Authors: Iwata Tetsuo , Uchida Teruo , Minami Shigeo
Published: June 2005

A new time-resolved photon-counting instrument with high data-gathering efficiency is described. The principle of operation is based on the measurement of the nanosecond temporal distribution of the emitted photon burst during the short duration of transient emission. The instrument is characterized by the unique capabilities of a modified vernier chronotron with plural coincidence circuits and serial-timing data memories, which serve as an efficient multichannel event-time analyzer of 1.5-ns time resolution. The data-gathering efficiency is improved by a factor of 20 or more in comparison with that of the conventional single-photon counting method. In regular operation, the time history of transient emission for the period of 144 ns is obtained; and for phenomena with longer duration, the time-scale expansion mode of operation is provided. To demonstrate the whole system performance, a fluorescence decay curve of 1-ppm quinine sulfate in 0.1-N H2SO4 is presented.
Spectral Efficiency of the SpectraSpan III Echelle Grating Spectrometer
Authors: Zander Andrew T. , Miller Myron H. , Hendrick Martha S. , Eastwood Delyle
Published: June 2005

The efficiency of an echelle grating spectrometer incorporating prism cross-dispersion is empirically evaluated over a broad wavelength range incorporating a large number of orders. A derived parameter, the spectrometer efficiency, proportional to the spectrometer luminosity, conveniently gauges dynamic features of the echelle efficiency. Characteristics of efficiency over broad wavelengths suggested by earlier work are clearly observed. The shift of blaze wavelength with decreasing order of diffraction, predicted in a recent model of echelle grating efficiency, is experimentally documented.
The Structure of Hexane Soot II: Extraction Studies
Authors: Akhter M. S. , Chughtai A. R. , Smith D. M.
Published: June 2005

Successive extraction of soluble components of hexane soot with a suite of solvents has been followed by CGC/MS, FT-IR, UV/Vis, fluorescence, and NMR spectroscopic analysis of these extracts. From these studies, additional understanding of the structure and reactivity of this material has emerged. A significant portion of the soot is extractable as polynuclear aromatic and aliphatic compounds, while the nonextractable solid structure, with both aromatic and aliphatic portions, contains such carbon-oxygen functionalities as acid anhydride, carbonyl, and ether linkages. A model of hexane soot as formed in flame is proposed on the basis of this work.
Application of Inductively Coupled Plasma Spectrometry (ICP) to the Analysis of Calcined Bauxites
Authors: Coedo A. Gomez , Fuentes F. J. Valle
Published: June 2005

Inductive coupled plasma (ICP) has been used with high sensitivity and wide linear response range for high concentrations of calcined bauxites. Previously, bauxites were subjected to an elemental qualitative analysis by means of the direct current arc emission spectrographic technique. The selection of specific analytical lines and spectral interferences in the ICP is reported and the relative standard deviation for the major elements is presented. The work is confirmed by a comparison of the results obtained by ICP vs. those attained by wet methods.
Spectral Studies of Actinide Elements by Resonance Ionization Mass Spectrometry
Authors: Donohue D. L. , Young J. P. , Smith D. H.
Published: June 2005

Resonance ionization mass spectrometry (RIMS) was applied to a spectral study of Th, U, Np, Am, and Cm in the wavelength region of 580–607 nm. One or more analytically useful RIMS peaks were observed for all these actinides except Cm. From the data presented, spectral interference among these elements can be assessed. Several new high-lying energy levels for these elements have been cataloged.
Cadmium(II)-Exchanged Zeolite as a Solid Sorbent for the Preconcentration and Determination of Atmospheric Hydrogen Sulfide II: Spectroscopic Techniques
Authors: Street Kenneth W. , Mark Harry B. , Vasireddy Sivasankararao , LaRue-Filio Rebecca A. , Anderson C. William , Fuller Michael P. , Simon Stephen J.
Published: June 2005

Instrumental techniques are compared for usage in the determination of atmospheric H2S which has been preconcentrated on Cd(II)-exchanged zeolite. The study covers the range of 0.01 to 100 μg of immobilized sulfide. For high concentrations (2–100 μg), combustion analysis followed by nondispersive IR is the simplest and most precise technique, and results with the use of this method are accurate to ±3% relative. In the range of 0.25–40 μg, the sulfide, after conversion to methylene blue, may be determined by conventional spectrophotometry, with a relative precision of ±13%. For the lowest concentration range investigated (0.01–2.0 μg), photoacoustic spectroscopy gave the only quantitative results after the H2S was converted to methylene blue.
Multivariate Least-Squares Methods Applied to the Quantitative Spectral Analysis of Multicomponent Samples
Authors: Haaland David M. , Easterling Robert G. , Vopicka David A.
Published: June 2005

In an extension of earlier work, weighted multivariate least-squares methods of quantitative FT-IR analysis have been developed. A linear least-squares approximation to nonlinearities in the Beer-Lambert law is made by allowing the reference spectra to be a set of known mixtures. The incorporation of nonzero intercepts in the relation between absorbance and concentration further improves the approximation of nonlinearities while simultaneously accounting for nonzero spectral baselines. Pathlength variations are also accommodated in the analysis, and under certain conditions, unknown sample pathlengths can be determined. All spectral data are used to improve the precision and accuracy of the estimated concentrations. During the calibration phase of the analysis, pure component spectra are estimated from the standard mixture spectra. These can be compared with the measured pure component spectra to determine which vibrations experience nonlinear behavior. In the predictive phase of the analysis, the calculated spectra are used in our previous least-squares analysis to estimate sample component concentrations. These methods were applied to the analysis of the IR spectra of binary mixtures of esters. Even with severely overlapping spectral bands and nonlinearities in the Beer-Lambert law, the average relative error in the estimated concentrations was <1%.
Optimization of Photothermal Refraction for Flowing Liquid Samples
Authors: Weimer Wayne A. , Dovichi Norman J.
Published: June 2005

A model has been developed for photothermal refraction using flowing liquid samples. In photothermal refraction, a cylindrical thermal lens is formed within the sample because of the temperature rise produced by the absorbance of a pump laser beam. This cylindrical thermal lens is intersected at right angles with a second probe laser. For static samples, the maximum signal results when the pump and probe beams are coplanar. Defocusing of the probe beam by the cylindrical thermal lens is detected as a change in the far-field probe beam center intensity. Flow acts to distort the temperature distribution by transporting heat down stream. For flowing samples, the optimum signal is found when the probe beam is located about one pump beam spot size down stream from the pump beam axis.
A Comparison of Data Reduction Techniques for Line-Excited Optoacoustic Analysis of Mixtures
Authors: Tilden Scott B. , Denton M. Bonner
Published: June 2005

The use of discrete line laser excitation for the optoacoustic analysis of gas mixtures holds promise as a formidable analytical tool. However, this technique presents challenging demands on the data reduction process to increase the reliability of the analytical results. The problems unique to this method which make data reduction difficult are discussed. Use of simultaneous equations, multivariate least-squares, and a new iterative coefficient weighted least-squares approach are compared. Data indicating the relative performance of these methods are presented.
Experimental Characterization of Aerosol Production, Transport, Vaporization, and Atomization Systems. Part I: Factors Controlling Aspiration Rates
Authors: Skogerboe R. K. , Freeland S. J.
Published: June 2005

This paper describes the results of the first stage of an investigation designed to extend present knowledge of the factors affecting aerosol production, transport, vaporization, and atomization in analytical spectroscopy systems. It focuses on factors controlling aspiration of aqueous solutions. The results demonstrate that the effect of gas flow on the pressure drop induced at the tip of the solution draw tube can be described by a simple linear equation; that the relationship between gas flow rate and solution nebulization rate can also be modelled by a simple equation; and that these relationships are not adequately represented by the Hagen-Poiseulle equation, as is often claimed.
Near-Infrared Spectrophotometric Methods Development with a Limited Number of Samples: Application to Carbonate in Geological Samples
Authors: Honigs D. E. , Hirschfeld T. B. , Hieftje G. M.
Published: June 2005

In the present study, an approach is described which can be used to create a near-infrared spectrophotometric calibration in a situation where only a limited number of training samples are available. The particular application studied is the determination of carbonate concentration in a series of 23 powdered geological samples. Because of the small size of the data set, unusual techniques were used to create the analytical calibration. The number of analytical wavelengths was determined by factor analysis. The analytical wavelengths and weighting coefficients were determined by means of a previously described algorithm. Finally, the calibration was confirmed by a cross-validation procedure and by the reconstruction of the spectrum of pure “carbonate” from the near-infrared reflectance spectra of the samples.
Pattern Recognition of Two-Dimensional Fluorescence Data Using Cross-Correlation Analysis
Authors: Rossi T. M. , Warner I. M.
Published: June 2005

An algorithm for spectral matching of excitation-emission matrices (EEMs) is reported. The pattern-recognition method developed operates completely in the frequency domain after Fourier transformation of unknown and standard EEMs. Spectral matches are evaluated by correlation and intervector distances between Fourier spectra of EEMs. Application of this method to single-component EEMs demonstrates the utility of pattern recognition for the identification of spectrally similar anthracene derivatives. In a study of multicomponent EEMs, mixtures of polynuclear aromatics (PNAs) are identified by comparison to a standard set of mixtures, and eigenvector deconvolution is coupled with pattern recognition for the identification of individual components in two-component mixtures. In addition, the feasibility of applying automatic pattern recognition to the identification of bacteria based on their uptake of fluorescent dyes is explored.
Emission FT-IR Analyses of Jet Fuel Deposits
Authors: Lauer James L. , Vogel Eter , Seng Gary T.
Published: June 2005

Deposits were collected on small flat and removable strips of metal from an aircraft fuel slowly flowing over them for varying lengths of time (up to 14 h). Both the strips and the fuel were heated to about 250°C. The fuel contained oxygen. After every test the deposit weight was determined with a microbalance, and the infrared emission spectrum of the deposit maintained at 100°C was recorded with a specially adapted Fourier spectrophotometer. Deposit thicknesses varied from 22 nm to 500 nm. Plots of deposit thickness squared vs. time were linear, with an abrupt change of slope after five hours of run time. Corresponding to these different slopes were also different infrared spectra, the earlier ones showing strong -C-O- bands around 1100 cm−1, the latter primarily -C=0 bands near 1700 cm−1. Fuels containing up to 1% of thiphene or pyrrole showed only the latter bands. These results are consistent with a diffusion mechanism dependent on the timely arrival at the liquid-deposit interface of a sufficient concentration of a reaction intermediate.
Rotational Isomers in Anhydrides from IR Spectroscopy and MO Calculations
Authors: Colthup N. B.
Published: June 2005

In this study ab initio MO calculations were used to calculate the relative energies of various types of C-O rotational isomers in acetic anhydride. MO calculations were also used to predict the IR intensity ratio for the in-phase and out-of-phase carbonyl stretch bands in acetic anhydride. A linear relationship was developed between the intensity ratio and the square of the tangent of the C-O dihedral angles. This relationship was used to show that crystalline stearic anhydride has a planar skeleton and stearic anhydride in the liquid state has a C-O dihedral angle of about 32°.
Effects of Solution Composition on the Physical Characteristics of Aerosols Produced by Nebulization
Authors: Skogerboe R. K. , Freeland S. J.
Published: June 2005

It has been confirmed that the size distribution of the analyte contained in an aqueous aerosol is affected by the chemical composition of the solution nebulized. The present work has shown that the addition of sodium to copper solutions shifts the aerodynamic and physical size distributions for the copper upward, while the sodium size distributions remain relatively constant. Examination of solid aerosols produced by flash evaporation of aqueous droplets has indicated that the particles tend to be hollow spheres which may encapsulate smaller spheres, as has been observed for particles emitted from combustion sources. The possible significance of droplet evaporation during aerosol transport is examined and judged to be a plausible and at least partial cause of the effects observed.
Quantitative XRF Analysis of Trace Barium in Porcelains by Source Excitation
Authors: Yap C. T. , Tang S. M.
Published: June 2005

Quantitative determination of barium in Chinese porcelains from the seventeenth century to modern times together with some modern non-Chinese porcelains was made with the use of calibration curves obtained by the addition method. All Chinese porcelains from K'ang Hsi (Kangxi, 1662–1722) up to World War II were found to have a barium content between 100 ppm and 130 ppm. For those made after World War II, the barium content varies from 60 ppm to 7000 ppm, and only a few pieces are in the range from 100 ppm to 130 ppm, making it possible to identify most of the modern fake reproductions.
Determination of Triglycerides on Cotton Fabrics Using Fourier Transform Attenuated Total Reflection Infrared Spectroscopy
Authors: Murthy R. S. Shreedhara , Leyden D. E. , Grime J. Keith
Published: June 2005

Triglycerides deposited on cotton fabric in the form of artificial body soil (ABS) were quantified with the use of ATR/FT-IR spectroscopy after ABS had been transferred onto the ATR crystal under pressure. This approach improved the signal-to-background ratio by avoiding interference from cellulose absorption, and improved precision as contact of the cloth sample with the ATR crystal was not necessary. ABS concentrations comparable to natural body soil levels were determined. This procedure was shown to be useful for following the depletion of “surface” ABS after different washing procedures.
The Power of Spectroscopic Methods in the Determination of the Relative Orientation of Guest Molecules in a Stretched Polyethylene (PE) Matrix
Authors: Konwerska-Hrabowska Joanna
Published: June 2005

Comparison of values for the relative orientation of pyrene guest molecules and PE host macromolecules obtained by spectroscopic measurements and by calculations of the minimum of the interaction energy between the guest and host molecules is presented. Accordance between both results as well as with the Groszek model is found.
Laser-Excited Atomic Fluorescence of Some Precious Metals and Refractory Elements in the Inductively Coupled Plasma
Authors: Huang X. , Lanauze J. , Winefordner J. D.
Published: June 2005

The combination of an excimer (XeCl) pumped pulsed dye laser with frequency-doubled output as an excitation source and the inductively coupled argon plasma (ICP) as an atom/ion reservoir was used in the study of the atomic fluorescence of Ag, Au, Hf, Ir, Mo, Nb, Pd, Pt, Ru, Ta, and Zr. The detection limits were found to be in the range of 1.3–58 ng mL−1 (ppb) with a linear dynamic range (LDR) of over four orders of magnitude, except for Au and Hf. These represent the first published results for laser-excited atomic fluorescence spectroscopy in the ICP cell for the elements studied, except for Mo and Zr, and the LODs found were superior to those obtained by flame atomic absorption spectroscopy (FAAS), except for Ag, Au, and Mo, and similar to those obtained by emission ICP.
High-Resolution Infrared Spectroscopy Using a Temperature-Controlled Long-Path Absorption Cell: The v3 Band of Uranium Hexafluoride at 16 μm
Authors: Kim K. C. , Reisfeld M. J.
Published: June 2005

High-resolution UF6 absorption spectra at 16 μm have been obtained with the use of tunable diode lasers and a long-pathlength (∼103-m) sample cell. The frequencies of the v3 Q-branch subband heads for both 238UF6 and 235UF6 have been determined, along with those for the ( v3 + v6) – v6 “hot-band” transition. Band contour studies have been carried out as a function of temperature, and comparisons are made with previous work.
Theory of Holographic Relaxation Spectroscopy with Nonsinusoidal Gratings
Authors: Shibata John H. , Johnson Charles S.
Published: June 2005

The theory of holographic relaxation experiments is presented with special attention given to nonsinusoidal laser-induced concentration patterns. Diffraction efficiencies are derived at all Bragg orders for photochromic volume gratings created both with crossed laser beams and by means of square-wave intensity patterns. Analytical equations are obtained for the square-wave case. The equations include real and imaginary parts of the complex index of refraction, the wavelength of the probe beam, and time dependence resulting from mass diffusion. Numerical evaluations are presented for first- and second-order diffraction from pure absorption gratings with various optical thicknesses as functions of exposure. It is concluded that square-wave grating profiles with optimized duty factors produce higher diffraction efficiencies under almost all conditions than do profiles created holographically. Square-wave exposure profiles are recommended for use in grating relaxation experiments because of both efficiency and experimental convenience. In general, the time dependence of transient signals is very complicated; but for low efficiencies, i.e., weak gratings, diffraction at the jth Bragg incidence is dominated by a single exponential term having a characteristic time of 1/[ D( jK)2] where D is the tracer diffusion coefficient and K is 2π divided by the grating period.