bluuebunny/crossref_metadata_2025 huggingface dataset:
Serum MMP-9/TIMP-1 and MMP-2/TIMP-2 ratios in multiple sclerosis: relationships with different magnetic resonance imaging measures of disease activity during IFN-beta-1a treatment
Authors: Avolio C , Filippi M , Tortorella C , Rocca M A , Ruggieri M , Agosta F , Tomassini V , Pozzilli C , Stecchi S , Giaquinto P , Livrea P , Trojano M
Published: June 2005

Matrix metalloproteinase-9 (MMP-9) is involved in blood-brain barrier (BBB) disruption in active multiple sclerosis (MS), while MMP-2 seems to be associated with the chronic progressive phase of the disease. Recombinant interferon beta-1a (rIFNβ-1a) is effective in restoring the BBB. We studied the relationships between serum MMP-9, MMP-2, TIMP-1 and TIMP-2 and different magnetic resonance imaging (MRI) measures of disease activity in MS patients during treatment with rIFNβ-1a. Twenty-one relapsing-remitting (RR) MS patients underwent longitudinally simultaneous blood withdrawals and MRI (before and after standard dose (SD) and triple dose (TD) of gadolinium (Gd)) examinations before and during 48 weeks of rIFNβ-1a (Rebif® 22 mcg three times a week) treatment. Serum MMP-9, MMP-2, TIMP-1 and TIMP-2 were measured, MMP-9 to TIMP-1 and MMP-2 to TIMP-2 ratios were calculated and the numbers of Gd-SD, Gd-TD, new-Gd-SD, new-Gd-TD and new-T2 lesions counted. Serum MMP-9/TIMP-1 ratio (P< 0.0001), as well as the numbers of ‘active’ lesions (P ranging from 0.0004 to 0.005) decreased during treatment. Moreover, serum MMP-9/TIMP-1 ratio proved to be a good positive predictor (estimate= 0.85; P> 0.05) of the numbers of MRI Gd-TD active lesions. These data confirm that serum MMP-9/TIMP-1 ratio may be viewed as a reliable marker and may be predictive of MRI activity in RR MS.
Acute partial transverse myelitis with normal cerebral magnetic resonance imaging: transition rate to clinically definite multiple sclerosis
Authors: Scott Thomas F , Kassab Salima L , Singh Shalu
Published: June 2005

Objective: To determine the long-term risk of developing clinically definite multiple sclerosis (CDMS) in patients with acute partial transverse myelitis (APTM) and normal cerebral magnetic resonance imaging (MRI) scans. Methods: We retrospectively studied 30 consecutive patients with clinical evidence of APTM. Patients with symmetric severe acute transverse myelitis were considered to have complete transverse myelitis and were excluded. All patients underwent spinal and cerebral MRIs, 13 underwent cerebrospinal fluid analysis and 11 patients underwent evoked potential studies. Various other studies were performed to assess for connective tissue disease and causes of APTM other than demyelinating disease. Results: After an average follow-up of 61 months, all laboratory and clinical evidence, including relapse history, indicated that three patients developed lesions on cerebral MRI and could be classified as CDMS by either Poser criteria (two patients) or MacDonald criteria (one patient). Relapses limited to the spinal cord seen clinically were seen in 14/30 (46.6%) patients. Oligoclonal bands were seen in 8/13 (62%) patients; one patient transitioned to CDMS. Unifocal lesions of the cord were seen in 19/30 (63%) patients, multifocal lesions were seen in 8/30 (27%) and 3/30 (10%) had negative MRIs. The three patients who converted to CDMS did so within five years of the onset of myelitis. Conclusion: APTM with normal cerebral MRI had a low rate of conversion to CDMS in this long-term study. To date, there have been only a few follow-up studies that have addressed this issue.
MRI results from the European Study on Intravenous Immunoglobulin in Secondary Progressive Multiple Sclerosis (ESIMS)
Authors: Fazekas F , Sørensen P S , Filippi M , Ropele S , Lin X , Koelmel H W , Fernandez O , Pozzilli C , O'Connor P , Enriquez M Maas , Hommes O R ,   ESIMS trialists
Published: June 2005

Background: Monthly application of high-dose intravenous immunoglobulin (IVIG) to patients with secondary progressive multiple sclerosis (MS) showed no clinical benefit in the European Study on Immunoglobulin in MS (ESIMS). Magnetic resonance imaging (MRI) results may provide insights into the morphologic consequences of such treatment. Methods: A total of 318 patients (mean age 44± 7 years) were enrolled in 31 European and Canadian centres and treated monthly with 1 g/kg body weight of IVIG or equivalent amounts of albumin 0.1% for 27 months. MRI was performed at baseline and after 12 and 24 months and comprised of conventional dual-echo T2-weighted and T1-weighted scans before and after application of 0.1 mmol/kg Gd-DTPA. Results: Similar to clinical variables, MRI measures at baseline were well comparable between treatment groups except for a somewhat lower mean number of contrast-enhancing lesions and number of active scans in IVIG-treated patients. Over the trial period there was almost no change of the T2-lesion load and the ‘black hole’ volume in both treatment groups and the cumulative number of contrast-enhancing lesions were similar. There was only a trend for fewer new or enlarged T2-lesions in IVIG patients, which disappeared after correction for the imbalance in the number of contrast-enhancing lesions at baseline. Brain volume in terms of a partial cerebral fraction decreased significantly less with IVIG than placebo treatment (final visit:-0.62± 0.88% versus-0.88± 0.91%; P= 0.009). This difference remained statistically significant with correction for active lesions at baseline (P= 0.02) and was seen primarily in male patients and those with an Expanded Disability Status Scale score ≥ 6 and no relapses in the two years before the study. Conclusion: The absence of significant differences in conventional MRI measures between both treatment groups parallels the negative clinical results of ESIMS. The causes for and possible long-term clinical effects of a lower rate of brain volume loss in IVIG patients should be explored further.
Eight-year immunogenicity and safety of interferon beta-1a-Avonex®treatment in patients with multiple sclerosis
Authors: Herndon Robert M , Rudick Richard A , Munschauer Frederick E , Mass Michele K , Salazar Andres M , Coats Michael E , Labutta Robert , Richert John R , Cohan Stanley L , Genain Claude , Goodkin Donald , Toal Martin , Riester Katherine
Published: June 2005

An open-label extension study of the phase III trial of intramuscular interferon beta-1a (IFNβ-1a-Avonex) was conducted to evaluate the immunogenicity and safety of IFNβ-1a-Avonex over six years in patients with relapsing multiple sclerosis (MS). Patients who participated in the pivotal phase III study were offered enrolment; entry was also open to patients who had not participated. All patients received IFNβ-1a-Avonex 30 mg intramuscularly once weekly for six years, for a treatment duration of up to eight years in patients who received IFNβ-1a-Avonex in the phase III trial. Serum levels of IFNβ antibodies were measured every six months using a screening enzyme-linked immunosorbent assay (ELISA) followed by an antiviral cytopathic effect assay to detect neutralizing antibodies (NAbs) in serum samples positive on ELISA. The incidence of adverse events and laboratory test results assessed safety. Of 382 total patients, 218 had participated in the phase III study (103 placebo, 115 IFNβ-1a-Avonex) and 164 had not participated; 24 of the 164 were IFNβ-naïve. At baseline, 281 patients were negative for IFNβ antibodies (NAb-). NAbs (titre≥ 20) developed at any time over six years in 5% of these patients. Of 140 patients who had been on IFNβ-1b-Betaseron, 49 were positive for NAbs (NAb+) at baseline; 11 of 115 who had been on IFNβ-1a-Avonex were NAb+ at baseline. Thirty-nine of 49 patients who had been on Betaseron and were NAb+ had titres <100; 36 of these 39 seroconverted to NAb-while on IFNβ-1a-Avonex, with a median time of approximately six months. Ten patients who had been on Betaseron had NAb titres ≥ 100; five remained NAb+ during six years on IFNβ-1a-Avonex and five seroconverted to NAb-, but only after at least two years. Five patients who had been on IFNβ-1a-Avonex during the clinical trial were NAb+ with titres <100 at baseline; four seroconverted to NAb-, with a median time of two to three years. Six patients who had been on IFNβ-1a-Avonex had NAb titres ≥100; five of these remained NAb+ at six years. No patient with a NAb titre >1000 seroconverted to NAb-, whether initially treated with IFNβ-1a-Avonex or -Betaseron. Adverse events were similar to those observed in the pivotal phase III trial. Results from this trial indicated that IFNβ-1a-Avonex was associated with a low incidence of NAbs and was well tolerated for up to eight years. Further, the results indicate that persistence of NAbs is dependent on titre and IFNβ product.
Performance of gasoline fuel cell cars - a simulation study
Authors: Fischer K , Rzepka M , Stimming U , Biermann J-W , Johannaber M , Wallentowitz H
Published: June 2005

This paper reports on the analysis and evaluation of different automobile traction concepts of an electrically powered compact class vehicle equipped with an energy converting fuel cell system. All simulation models of the fuel cell cars are based on an on-board gasoline reformer unit. As fuel cell systems both a solid oxide fuel cell (SOFC) and a polymer electrolyte membrane fuel cell (PEMFC) are compared. For a study of the influence of the energy management concept on system performance, the fuel cell car is eventually equipped with an auxiliary energy buffering battery. A variety of studies are shown concerning the performance and energy consumption of the different systems as well as sensitivity studies for selected system parameters.
Analysis of out-of-plane motion of a disc brake system using a two-degree-of-freedom model with contact stiffness
Authors: Oh J-E , Joe Y-G , Shin K
Published: June 2005

A two-degree-of-freedom out-of-plane model with contact stiffness is presented to describe dynamic interaction between the pad and disc of a disc brake system. It is assumed that the out-of-plane motion of the system depends on the friction force acting along the in-plane direction. The dynamic friction coefficient is modelled as a function of both in-plane relative velocity and out-of-plane normal force. When the friction coefficient depends only on the relative velocity, the contact stiffness has the role of negative stiffness. The results of stability analysis show that the stiffnesses of the pad and disc are equally important. Complex eigenvalue analysis is conducted for the case where the friction coefficient is also dependent on the normal force. The results further verify the importance of the stiffness. It has also been found that increasing the gradient of the friction coefficient with respect to the normal force makes the system more unstable. Non-linear analysis is also performed to demonstrate various responses. Comparing the responses with experimental data has shown that the proposed model may qualitatively well represent a certain type of brake noise.
Development of a fuel stratification spark ignition engine
Authors: Li Y , Zhao H , Leach B , Ma T
Published: June 2005

A fuel stratification concept is being researched and developed in a three-valve twin-spark ignition engine. This concept requires that two different fuels or fuel components be introduced into the cylinder separately through two independent inlet ports. The fuels will be stratified laterally by means of strong tumble in the cylinder. Similar to the traditional air/fuel stratification engine, this fuel stratification engine can operate in very lean mixture or high exhaust gas dilution at part loads to reduce fuel consumption and NOx emissions. While at high-load operation, a higher compression ratio may be allowed owing to a potential increase in antiknock features if the lower research octane number (RON) fuel or component is ignited first, leaving the higher RON fuel in the end gas region. As a result, the fuel economy can be improved not only at part loads but possibly at full loads as well. This paper reports the development of such a fuel stratification engine. Firstly, the intake system of the engine was modified to produce a strong tumble flow which was measured by a digital particle image velocimetry (PIV) system. Then, a two-tracer planar laser induced fluorescence (PLIF) system was developed to visualize the fuel stratification in the cylinder. The engine combustion at part and full loads was also tested and analysed from cylinder pressure history. These research results show that the present strong tumble flow was characterized by a symmetrically distributed mean velocity in the intake stroke and a very small velocity component along the direction of the tumble rotational axis in the compression stroke. This flowfield created good fuel stratification laterally. The lean burn limit was considerably extended at part loads, and the knock limit at high loads also had a noticeable difference when higher and lower RON fuels respectively were ignited first.
Real-world performance of catalytic converters
Authors: Samuel S , Morrey D , Fowkes M , Taylor D H C , Garner C P , Austin L
Published: June 2005

This paper investigates experimentally the performance of a three-way catalytic (TWC) converter for real-world passenger car driving in the United Kingdom. A systematic approach is followed for the analysis using a Euro-IV vehicle coupled with a TWC converter. The analysis shows that the real-world performance of TWC converters is significantly different from the performance established on legislative test cycles. It is identified that a light-duty passenger vehicle certified for Euro-IV emissions reaches the gross polluting threshold limits during real-world driving conditions. This result is shown to have implications for overall emission levels and the use of remote emissions sensing and on-board diagnostics (OBD) systems.
Effects of dimethyl carbonate fuel additive on diesel engine performances
Authors: Zhang G D , Liu H , Xia X X , Zhang W G , Fang J H
Published: June 2005

The physical and chemical properties of some oxygenated compounds are discussed, including dimethoxymethane (methylal, or DMM), dimethyl carbonate (DMC), and ethyl acetate. In particular, DMC may be a promising additive for diesel fuel owing to its high oxygen content, no carbon-carbon atomic bonds, suitable boiling point, and solubility in diesel fuel. The aim of this research was to study the combustion characteristics and performance of diesel engines operating on diesel fuel mixed with DMC. The experimental results have shown that particulate matter (PM) emissions can be reduced using the DMC oxygenated compound. The combustion analysis indicated that the ignition delay of the engine fuelled with DMC-diesel blended fuel is longer, but combustion duration is much shorter, and the thermal efficiency is increased compared with that of a base diesel engine. Further, if injection is also delayed, NOx emissions can be reduced while PM emissions are still reduced significantly. The experimental study found that diesel engines fuelled with DMC additive had improved combustion and emission performances.
Engine performance and emission characteristics of a compression ignition engine fuelled with diesel/dimethoxymethane blends
Authors: Ren Y , Huang Z H , Jiang D M , Liu L X , Zeng K , Liu B , Wang X B
Published: June 2005

The performance and emissions of a compression ignition engine fuelled with diesel/dimethoxymethane (DMM) blends were studied. The results showed that the engine's thermal efficiency increased and the diesel equivalent brake specific fuel consumption (b.s.f.c.) decreased as the oxygen mass fraction (or DMM mass fraction) of the diesel/DMM blends increased. This change in the diesel/DMM blends was caused by an increased fraction of the premixed combustion phase, an oxygen enrichment, and an improvement in the diffusive combustion phase. A remarkable reduction in the exhaust CO and smoke can be achieved when operating on the diesel/DMM blend. Flat NO x/smoke and thermal efficiency/smoke curves are presented when operating on the diesel/DMM fuel blends, and a simultaneous reduction in both NO x and smoke can be realized at large DMM addition. Thermal efficiency and NO x give the highest value at 2 per cent oxygen mass fraction (or 5 per cent DMM volume fraction) for the combustion of diesel/DMM blends.
Design guidelines for pregnant occupant safety
Authors: Acar B S , Weekes A M
Published: June 2005

During pregnancy a woman's body undergoes a considerable change in size and shape, and this can impact upon her safety during car travel. The two main issues are proper seat belt use and positioning, and steering wheel clearance. A comprehensive analysis of the questionnaire responses by pregnant women and anthropometric measurements demonstrates that the difficulties experienced can be explained by the physical changes and interactions throughout the body during gestation. Analysis of the anthropometry of pregnant women highlights that many pregnant users could easily be excluded from designs inadvertently if the design is based on males or non-pregnant females. Thus incorporation of pregnant women's anthropometry into automotive design could reduce the exclusion rates and alleviate problems. This paper presents guidelines for the automotive industry generated from experiences and anthropometry of pregnant women, with the aim of improving safety for pregnant car occupants.
Optimal control of an electrorheological fluid suspension system for tracked vehicles
Authors: Choi S B , Park D W , Lee D Y
Published: June 2005

In this paper, a controllable electrorheological fluid suspension system (ERSS) is proposed for a tracked vehicle. After identifying the Bingham properties of an electrorheological fluid, a double-rod-type ERSS is devised, and its damping characteristics are evaluated with respect to the intensity of the electric field. Subsequently, the governing equation of motion of a tracked vehicle featuring the ERSS is established followed by the formulation of a linearized state space model. An optimal controller integrated with Kalman filter is then designed in order to suppress unwanted vibrations of the tracked vehicle subjected to bump and random road excitations. Control performances such as vertical acceleration at the centre of gravity are evaluated in both time and frequency domains.
Performance and emissions characteristics of biodiesel from soybean oil
Authors: Canakci M
Published: June 2005

Biodiesel is an alternative diesel fuel that can be produced from renewable feedstocks such as vegetable oils, waste frying oils, and animal fats. It is an oxygenated, non-toxic, sulphur-free, biodegradable, and renewable fuel. Many engine manufacturers have included this fuel in their warranties since it can be used in diesel engines without significant modification. However, the fuel properties such as cetane number, heat of combustion, specific gravity, and kinematic viscosity affect the combustion, engine performance and emission characteristics. In this study, the engine performance and emissions characteristics of two different petroleum diesel fuels (No. 1 and No. 2 diesel fuels) and biodiesel from soybean oil and its 20 per cent blends with No. 2 diesel fuel were compared. The results showed that the engine performance of the neat biodiesel and its blend was similar to that of No. 2 diesel fuel with nearly the same brake fuel conversion efficiency, and slightly higher fuel consumption. CO2 emission for the biodiesel was slightly higher than for the No. 2 diesel fuel. Compared with diesel fuels, biodiesel produced lower exhaust emissions, except NO x.
Two-Frequency CARS for Mixture Analysis Using Pentacene in p-Terphenyl as a Model
Authors: Steehler Jack K. , Wright John C.
Published: June 2005

The usefulness of multiresonant nonlinear spectroscopy for analyzing complicated mixtures requires understanding of the factors controlling the relative signal positions and intensities of individual components. In this study the effects of different types of detuning from resonance, of the interactions of such detunings, and of the incident laser powers are illustrated. CARS spectra specific to the different pentacene sites in p-terphenyl are observed for different types of detunings from resonance, and the complications introduced by multiple components are interpreted. Population changes at moderate laser powers due to resonance with the allowed S0 to S1 transition lead to striking changes in the observed spectra, and markedly affect the interpretation of the observed resonances.
Quantitative Depth Profiling of Biporous Nickel Electrodes by Frequency-Domain Laser-Induced Photoacoustic Spectroscopy
Authors: Mandelis Andreas , Lymer John D.
Published: June 2005

Frequency-domain Photoacoustic Spectroscopy (PAS) was used with a He-Ne laser exciting beam to probe commercially available, powdered and pressed nickel electrodes with dual-porosity profiles. The frequency response of the electrodes was shown to be capable of providing quantitative information about the thermal conductivity and diffusivity of each of the two porous layers, provided the depth of the porosity junction in the electrode bulk is known. The reasonable agreement of the experimental data with a one-dimensional mathematical model of the photoacoustic response from a two-layer, photoacoustically saturated, continuous system indicates that powdered and pressed nickel electrodes behave photoacoustically approximately like a simple continuous composite-layer solid. This conclusion, together with experimental PAS results from uniporous electrodes, emphasizes the high potential of photoacoustic spectroscopy as a nondestructive, depth profiling, analytical technique for the determination of complex porosity profiles in electrodes manufactured for use in electrochemical energy conversion devices, such as fuel cells.
A Simple Graphical Procedure for Rapid Estimation of Ash in Coal by X-Ray Back-Scattering
Authors: Pandey H. D. , Prasad M. S.
Published: June 2005

This paper describes a simple graphical calibration procedure for rapid determination of ash content in coal samples. The results obtained with this procedure are compared with those obtained earlier with the use of a regression equation. The two results are found to be in agreement.
Characteristics of Capillary Discharge Lamp Developed for Determination of S, P, Se, and as by Flame Atomic Absorption Spectroscopy
Authors: Lowe M. D. , Sutton M. M.
Published: June 2005

The characteristics of a capillary discharge lamp, developed as a spectral source for the measurement of sulphur, phosphorus, selenium, and arsenic concentrations by flame atomic absorption spectroscopy, have been determined. Atomic spectral lines for each of the elements were produced when flowing mixtures of helium and vapor of the element, or a compound of the element, were passed through a quartz capillary discharge tube. Absorbance-concentration relationships, together with analytical sensitivities and detection limits, were obtained for sulphur, phosphorus, selenium, and arsenic with the use of a modified flame atomic absorption spectrophotometer, the optical system of which was purged with argon when necessary. The capillary discharge lamp readings were compared with measurements made under similar operating conditions with selenium and arsenic hollow cathode lamps. The capillary discharge lamp results were also compared with those obtained by other workers using electrodeless discharge lamps, modified hollow cathode lamps, and controlled temperature-gradient lamps. It was evident that the capillary discharge lamp possesses performance characteristics which make it potentially suitable as a spectral source for atomic absorption spectroscopy. Sensitivities and detection limits obtained with the use of this novel lamp were similar to those reported for other spectral sources.
Optical Constant Determination of Thin Polymer Films in the Infrared
Authors: Graf R. T. , Koenig J. L. , Ishida H.
Published: June 2005

Thin films of poly(vinyl chloride), poly(methyl methacrylate), and poly(styrene) were analyzed by Fourier transform infrared spectroscopy. The interference fringes present in the transmission spectra of these samples were used to determine film thickness and average refractive index. Subsequent Kramers-Kronig analysis of these transmission spectra provided the dispersion of the refractive index and the absorption index across the entire mid-infrared region. Interference fringes were absent in the optical constant spectra, and good agreement was obtained between our optical constant spectra and those of other authors.
Measurement of Monoatomic Vapor Concentrations of Some Elements by Atomic Absorption Spectrophotometry: Cu, Ag, Au, Mn, and Al
Authors: Panday V. K. , Ganguly A. K.
Published: June 2005

Measurement of the absorbance of resonance radiation from a hollow cathode lamp has been used to study the concentration of monoatomic metal vapor in equilibrium with its solid phase in an inert argon atmosphere (two Torr) over a pressure range 10−7 – 10−4 Torr for copper, silver, gold, manganese, and aluminum. The results obtained by this technique are compared with the vapor pressure data obtained by other workers using different techniques. The monoatomic vapor pressure data plotted against the reciprocal of temperature give a straight line, and the mean enthalpies of vaporization have been calculated from the slope of this line. The enthalpies are in agreement with the values obtained by earlier investigators using different techniques for copper, silver, gold, and manganese, but tend to be lower in the case of aluminum. The absolute vapor pressures calculated by this approach are higher for aluminum in the range of investigations.
Comparison of Calculated Detection Limits in Molecular Absorption, Molecular Luminescence, Raman, Molecular Ionization, and Photothermal Spectrometry*
Authors: Winefordner J. D. , Rutledge M.
Published: June 2005

Detection limits for absorption, luminescence, photoionization, Raman, and photothermal molecular spectrometric methods are calculated from signal-to-noise expressions. The detection limits (in m−3) represent the best possible values by the various methods, since the limiting noises in each case were chosen. Molecular luminescence methods, with laser excitation, approach 1 species/cm3. Methods relying upon two (or more) laser wavelengths generally have much poorer detection limits than the simpler single-wavelength methods.
Infrared Intensities of Liquids I: Determination of Infrared Optical and Dielectric Constants by FT-IR Using the CIRCLE ATR Cell
Authors: Bertie John E. , Eysel Hans H.
Published: June 2005

The CIRCLE ATR accessory has been used to measure the optical and dielectric constants of organic liquids and water. The method, based on Fresnel's equations, is described in detail, and the agreement between the results obtained and literature values is shown to be adequate for chemical use. The utility of optical and dielectric constants for the calculation of traditional infrared intensities in liquids and of dipole moment derivatives is outlined.
A Thin-Layer Electrochemical Cell for Infrared Spectroscopic Measurements of the Electrode/Electrolyte Interface
Authors: Seki H. , Kunimatsu K. , Golden W. G.
Published: June 2005

A thin-layer electrochemical cell which allows for the convenient measurement of infrared reflection-absorption spectra (IRRAS) of the electrode/electrolyte interphase has been designed and built. In order to minimize the thickness of the electrolyte in front of the electrode surface, one mounts the working electrode on the end of a piston so that it can be pressed against an infrared window. Infrared radiation is then reflected from the electrode surface via the infrared window without experiencing severe attenuation due to the electrolyte. Contaminants are minimized by the machining of both the cell body and piston from an inert fluorocarbon plastic. Calcium fluoride was chosen as the window material because of its transparency, its low refractive index, and its low solubility in aqueous electrolyte. The use of this cell in a Fourier transform infrared reflection-absorption spectrometer utilizing polarization modulation is described. The IRRAS spectra obtained from this cell have been analyzed with the use of the generalized Fresnel equations for stratified media. Some of the computational results for the water/silver electrode interphase are used to interpret the measured spectra of water near the electrode. The discussion includes infrared intensity distributions in aqueous media and their influence on the IRRAS measurement.
Infrared Intensities in Liquids II: Accuracy of FT-IR Transmission Measurements
Authors: Bertie John E. , Jones R. N. , Behnam V.
Published: June 2005

The absorption intensities of organic liquids have recently been measured against a primary standard by dispersive spectroscopy. No primary standard is known that can be used with rapid-scanning FT-IR spectrometers. Accordingly, we have remeasured the absorption intensities of C6H6C(ℓ ), CH2C12(ℓ ), and C6F6(ℓ ), largely in 500-μm thick cells, by FT-IR spectroscopy, and we compare the results with those of the calibrated dispersive spectroscopy. The agreement is excellent. Further evidence about the reproducibility of the intensities of these bands in different laboratories and on different instruments is desirable, because some of these bands may prove to be useful as secondary standards of photometric accuracy in transmission spectroscopy.
Linearization and Scatter-Correction for Near-Infrared Reflectance Spectra of Meat
Authors: Geladi P. , MacDougall D. , Martens H.
Published: June 2005

This paper is concerned with the quantitative analysis of multicomponent mixtures by diffuse reflectance spectroscopy. Near-infrared reflectance (NIRR) measurements are related to chemical composition but in a nonlinear way, and light scatter distorts the data. Various response linearizations of reflectance (R) are compared ( R with Saunderson correction for internal reflectance, log 1/ R, and Kubelka-Munk transformations and its inverse). A multi-wavelength concept for optical correction (Multiplicative Scatter Correction, MSC) is proposed for separating the chemical light absorption from the physical light scatter. Partial Least Squares (PLS) regression is used as the multivariate linear calibration method for predicting fat in meat from linearized and scatter-corrected NIRR data over a broad concentration range.

All the response linearization methods improved fat prediction when used with the MSC; corrected log 1/ R and inverse Kubelka-Munk transformations yielded the best results. The MSC provided simpler calibration models with good correspondence to the expected physical model of meat. The scatter coefficients obtained from the MSC correlated with fat content, indicating that fat affects the NIRR of meat with an additive absorption component and a multiplicative scatter component.
DEPT NMR Spectra of Copolymers
Authors: Newmark Richard A.
Published: June 2005

DEPT (Distortionless Enhancement by Polarization Transfer) spectra have been obtained on eight commercial polymers in order that the general applicability of this new multipulse technique for the assignment of carbon multiplicity in their proton noise decoupled 13C NMR spectra might be assessed. The spin-lattice and spin-spin relaxation times have been measured and correlated with the quality of the edited DEPT spectra.
Experimental Proof of the Relation between Thickness of the Probed Surface Layer and Absorbance in FT-IR/ATR Spectroscopy
Authors: Ohta Koji , Iwamoto Reikichi
Published: June 2005

Experimental investigation has been made of the relation of absorbance of a band in FT-IR/ATR spectroscopy to the thickness of the probed surface layer from the measurements of two-layered samples. The two-layered samples are composed of a polystyrene surface layer varying in thickness from 0.01 to 3.64 μm and a polyurethane base layer of 100 *im thickness. The component spectrum of the surface or base layer was separated by spectral subtraction. FT-IR/ATR spectroscopic measurements were mostly measured by nonpolarized incident light. The relation of observed absorbances of several selected bands of both the surface and base layers to the thickness of the surface layer was compared with the theoretical calculations from Harrick's equation. In the comparison, the effect of “nonpolarization” of the incident light was corrected for the observed absorbances. The agreement was excellent between the observation of and the theoretical calculation for both the surface and base layers. A method was proposed to determine the thickness of the spectrally separable surface layer on a film. The usefulness of this method was demonstrated by application to the redetermination of the thickness of the surface layer of the present two-layered samples. An expression was proposed to give the contribution of a surface layer of a certain thickness to the total absorbance of a band in ATR spectroscopy.
Elimination of the Intraion Spectral Interference between the 5D0 and 5D1 Emission Bands of Eu3+ in EuP5O14 by Using the Time-Resolved Spectroscopy Technique
Authors: Laulicht I. , Peer I.
Published: June 2005

The advantage of the time-resolved spectroscopy technique for reducing the spectral interference between the 5D0 and 5D1 emission lines of Eu3+ ions in EuP5O14 crystals is explained in detail. It is shown that this technique may be very helpful for rare earth ions fluorescence studies in general whenever a group of two or more neighboring levels emit photons to the same lower levels but their lifetimes are different. The wavelengths of many new lines of the 5D0 → 7Fj (j = 3–6) emission bands of Eu3+ in EuP5O14 are measured by this technique.
Laser-Enhanced Ionization of Refractory Elements in a Nitrous Oxide-Acetylene Flame
Authors: Messman Jerry D. , Schmidt Norman E. , Parli Joe D. , Green Robert B.
Published: June 2005

Laser-enhanced ionization (LEI) spectrometry using a water-cooled electrode immersed directly in a nitrous oxide-acetylene flame has been examined for the determination of refractory elements. LEI detection limits for refractory elements in aqueous solution are comparable to or better than detection limits obtained by flame atomic absorption, plasma emission, and atomic fluorescence techniques. Only graphite furnace atomic absorption spectrometry exhibits superior detectability for certain refractory elements in aqueous solution over LEI spectrometry using a nitrous oxide-acetylene flame. The successful application of the nitrous oxide-acetylene flame now extends the applicability of LEI spectrometry to include most of the elements in the periodic table which can be determined by other common atomic spectrochemical techniques.
Microliter Sample Introduction for ICP-AES
Authors: Faske Arthur J. , Snable Kimberley R. , Boorn Andrew W. , Browner Richard F.
Published: June 2005

A simple Flow Injection/Inductively Coupled Plasma-Atomic Emission Spectrometry system is described. The analytical performance, in terms of linearity, precision, and detection limits, was investigated for both aqueous and organic solvents. Acceptable detection limits were obtained with the use of approximately one-hundreth of the minimum sample volume required for continuous aspiration. Some deterioration of detection limits, however, was observed. The suitability of this system to biological samples was demonstrated by the analysis of iron- and cobalt-rubredoxins and National Bureau of Standards' Bovine Liver standard reference material.
Xenon-Lamp-Excited Fluorimetry of Several Anthracene Derivatives in a Supersonic Jet
Authors: Yamada S. , Smith B. W. , Voigtman E. , Winefordner J. D.
Published: June 2005

A simple and highly sensitive supersonic jet fluorimeter using a xenon arc lamp is described. Well-resolved fluorescence spectra were obtained for anthracene, 9-methylanthracene, and 9-chloroanthracene. Simultaneous identification of three compounds out of the mixture of four anthracenes was successful.
Application of Factor Analysis to the Analysis of the Kinetics and Mechanism of the X-Ray-Induced Decomposition of Potassium Perchlorate
Authors: Gilbert R. A. , Llewellyn J. A. , Swartz W. E.
Published: June 2005

Factor analysis has been applied to the analysis of the x-ray-induced decomposition of sodium Perchlorate, which yields chlorate and chloride as products. The analysis indicates that the chlorate ion cannot be an intermediate in the perchlorate-to-chloride reduction, as has been reported. A new mechanism consistent with the analysis and rate data for the decomposition are discussed.
Performance of an FT-IR with a Cube-Corner Interferometer
Authors: White Robert L.
Published: June 2005

The stability and performance of a Fourier transform infrared spectrometer with a cube-corner interferometer is investigated. Evaluation of instrument performance is based on results from interferogram subtraction experiments, 100% line interpretations, and comparison with theory. It is demonstrated that cube-corner retroreflectors compensate for interferometer moving-mirror tilt, making possible accurate spectroscopic measurements well into the visible region of the electromagnetic spectrum. In addition, cube-corner interferometers have potential for true dual-beam FT-IR measurements.
Alkali Halide Pellets of Deuterated Compounds for Infrared Spectrometry
Authors: MacCarthy Patrick
Published: June 2005

Methods for preparing alkali halide pellets of compounds deuterated at active hydrogen sites were investigated and the basic underlying problems were identified. As a result, a simple technique suitable for routine laboratory use has been developed for pelletizing deuterated compounds of this type for infrared spectrometry.
Automatic Tracing and Presentation of Interpretation Rules Used by PAIRS: Program for the Analysis of IR Spectra
Authors: Tomellini Sterling A. , Hartwick Richard A. , Woodruff Hugh B.
Published: June 2005

PAIRS (Program for the Analysis of Infrared Spectra) has been modified to allow the user automatically to trace and understand the interpretation decision making process. The added capability of the interpreter greatly increases its usefulness as a research tool. The generation and testing of new interpretation rules is also easier with the use of the improved interpreter. A description of the program, including changes, and an example of the added capabilities are presented.
Site-Selective Nonlinear Four-Wave Mixing by Multiply Enhanced Nonparametric and Parametric Spectroscopy
Authors: Lee S. H. , Steehler J. K. , Nguyen D. C. , Wright J. C.
Published: June 2005

A family of nonlinear four-wave mixing techniques that are capable of site-selective organic spectroscopy are presented. Three lasers are used in the methods in order to achieve fully resonant mixing. Three lasers are shown to provide better sensitivity, selectivity, and versatility in the study of ground and excited electronic state vibrational spectroscopy. New approaches become possible in the establishment of resonances that translate the output signal from the normal Stokes or anti-Stokes side of the lasers to intermediate positions that are free of fluorescence interference. These new methods are divided into Multiply Enhanced Parametric Spectroscopy (MEPS) and Multiply Enhanced Nonparametric Spectroscopy (MENS), depending upon the spectroscopic characteristics for site-selective applications. The characteristics of MEPS and MENS are found to be quite different and depend upon the number and separation of the sites, the power of the lasers, the relative shifts of the levels, and the correlation effects in the inhomogeneous broadening. The feasibility of MENS and the site-selective capability of both CARS and MENS is demonstrated experimentally with the use of the pentacene: p-terphenyl system as a model.
Synchronous Scanning Methods for Organic Spectroscopy with Fully Resonant Four-Wave Mixing
Authors: Nguyen D. C. , Wright J. C.
Published: June 2005

New synchronous scanning methods are developed for fully resonant four-wave mixing experiments with three input frequencies. Enhanced sensitivity and selectivity are observed for the vibrational and vibronic resonances that are coupled, consequently simplifying the spectral information obtained. The factors affecting selectivity and spectral simplification are discussed. Spectra obtained with the use of two-laser and three-laser CARS reveal various schemes of multiple resonance. Under resonant excitation at moderate power, saturation and power broadening reduce the effective electronic resonance enhancement. Resonances based on coupling between vibrational and vibronic levels are less susceptible to such power-induced phenomena. It is demonstrated that four-wave mixing with three input lasers provides the capabilities of measuring intermode vibronic coupling terms of the third-order susceptibility and performing fully resonant nonparametric four-wave mixing experiments that have the same characteristics as CSRS but are free from molecular fluorescence.
Coherent Anti-Stokes Raman Spectroscopy of Commercial Oil Samples
Authors: van Hare D. R. , Carreira L. A. , Rogers L. B.
Published: June 2005

Three commercial oil samples were analyzed with the use of the selectivity of resonance CARS. No fractionation procedures were used; the oil samples were simply dissolved in an appropriate solvent and pumped from 365 nm to 480 nm. All three samples could be differentiated by characteristic Raman bands at various pump wavelengths. In addition, comparisons between the CARS spectra of the oil samples and the CARS spectra of pure PAHs at the same pump wavelength yielded tentative identifications of perylene and benzo(ghi)perylene in two of the samples.
Alkyl Chain Length and the Spectral Characteristics of p-Aminophenones
Authors: Pan Huo Ping , Okuno Iwao
Published: June 2005

We report on the syntheses of some p-aminophenones with different lengths in their alkyl chains. In the mass spectra, beginning with p-amino- n-butyrophenone, the m/e 135 ion forms and its intensity increases sharply with alkyl chain length. The lengthening of the alkyl chain increases the intensity of the IR CH stretching absorption in the region of 3000–2800 cm−1, but decreases the complexity in the absorption region from 3.00 ppm to about 0.80 ppm in the PMR spectra
Protein Conformation by Infrared Spectroscopy: Resolution Enhancement by Fourier Self-Deconvolution
Authors: Yang Wang-Jih , Griffiths Peter R. , Byler D. Michael , Susi Heino
Published: June 2005

Fourier self-deconvolution (FSD) has been employed to enhance the resolution of the infrared spectra of proteins in the solid state and in D2O solution. The feasibility of using diffuse reflectance spectrometry for measuring the infrared spectra of solid proteins has been demonstrated. FSD permits inherently broad absorption bands to be resolved into distinct peaks which can be associated with specific protein secondary structures. Because the areas of the resolved peaks are the same as the areas of the previously unidentifiable components, this new method should enable quantitative estimates of the proportion of each conformation in a protein to be calculated.
Instrumental Dependence of Optimal Interferogram Sampling for Gram-Schmidt Reconstructions of Gas Chromatography/Fourier Transform Infrared Data
Authors: Sparks Daniel T. , Owens Patrick M. , Williams Stephen S. , Wang Ching Po , Isenhour T. L.
Published: June 2005

Three different commercial FT-IR spectrometers were used to collect GC/FT-IR data for assessing the effects of interferometer stability on the optimal parameters to use for Gram-Schmidt chromatographic reconstructions. Disagreements in the literature regarding the optimum region of the interferogram to use for vector reconstructions are shown to result from interferometer stability differences. It is determined that the use of double-sided vectors in the Gram-Schmidt calculation simplifies the choice of reconstruction parameters. Additionally, it is demonstrated that the Gram-Schmidt algorithm outperforms integrated spectral absorbance methods for any logical choice of Gram-Schmidt parameters.
Development of a Microwave-Induced Nitrogen Discharge at Atmospheric Pressure (MINDAP)
Authors: Deutsch R. D. , Hieftje G. M.
Published: June 2005

A microwave-induced plasma has been sustained with the use of nitrogen as the nebulizer and plasma supporting gas. A concentric tube torch was constructed so the plasma could be easily ignited and maintained. This new plasma emission source has a flame-like appearance and extends 10 cm beyond the cavity, at an applied power of 250 W. The nitrogen plasma readily accepts aerosol samples and is compatible with sample introduced from a conventional nebulizer system. The radial (side-on) optical viewing configuration was found to have lower background emission than the more commonly employed axial (end-on) configuration. Optimum operating conditions were established from the effects of applied power, flow rate, and signal-to-background noise on the intensity of both atom and ion transitions. A discussion of the background spectral features and the analytical potential of this new source is presented.
The Use of Principal Components in the Analysis of Near-Infrared Spectra
Authors: Cowe Ian A. , McNicol James W.
Published: June 2005

The statistical technique of principal components is used to analyze two sets of near-infrared spectra, wheat flour samples for which % moisture and % protein values are included, and milled barley samples for which hot water extract values are included. The methodology and interpretation of this technique are described within the context of NIR data, and its advantages both in providing insight into the variation of the spectra, and as a method of avoiding the problems caused by highly correlated reflectance energy values in the derivation of calibration equations, are highlighted. In each set of samples the first principal component accounts for the vast majority of the variation. These components also have an almost identical shape, which is interpreted as reflecting particle size. The second wheat component and the third barley component are also almost identical, with a shape very similar to that of the spectrum of water. Both fourth components share peaks at points in the spectrum which are used by fixed-filter instruments to measure protein in cereals.
Evaluation of Microwave-Induced Air-Plasma as an Excitation Source
Authors: Zhang Y. K. , Hanamura S. , Winefordner J. D.
Published: June 2005

A single-electrode atmospheric pressure microwave discharge air-plasma is reported. Fundamental characteristics, such as the effects of microwave power, auxiliary air flow, and nebulizer air flow on emission intensity, detection limits, and dynamic ranges for twelve elements and several interference experiments are reported. The plasma temperature is found to be about 4700°K. This simple system can be applied to the spectrochemical analysis of solution samples. The results with the use of this system to determine calcium, sodium, and potassium in SRM-1566 (oyster tissue) and SRM-92 (low-boron glass) show excellent agreement with the NBSs certified values.
Raman Spectral Study of the Composition of Basic Silicate Solutions
Authors: Dutta Prabir K. , Shieh Dah-Chung
Published: June 2005

Raman spectral data are reported for silicate solutions at varying hydroxide ion concentrations. The gradual change in the spectra is explained as being due to various monomeric, dimeric, cyclic, and polymeric silicate species in solution. Band assignments are made by comparison with the Raman spectra of phosphates and crystalline silicate minerals.
Oriented Polycrystalline Films for Infrared Spectroscopic Studies
Authors: Landry J. M. , Katon J. E. , Hughes J. M.
Published: June 2005

Polarized infrared spectra obtained from oriented samples are very useful for determining vibrational assignments and/or crystal structure information. The technique of growing highly oriented polycrystalline films for such studies has been used for some time to obtain mid-infrared data of organic compounds. This paper summarizes the important factors in the growth of such films and describes extensions of the technique to organometallic and inorganic compounds and to the far-infrared spectral region. Implications of the technique with respect to crystal orientation and polymorphism are also considered.