bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Soil Nitrate and Water Content Using Attenuated Total Reflectance Spectroscopy
Authors: Borenstein A. , Linker R. , Shmulevich I. , Shaviv A.
Published: October 2009

Direct determination of nitrate and soil moisture can significantly improve N-application management and thus reduce N-derived environmental pollution related to agriculture. Several studies have shown that Fourier transform infrared attenuated total reflectance (FT-IR/ATR) spectroscopy could be used to estimate the nitrate content of standardized soil pastes. Paste standardization appeared to be the main obstacle to in situ application of this approach, and the present study shows how FT-IR/ATR can be used to estimate both water content and nitrate concentration of field soil samples. Water content and nitrate concentration are determined sequentially using two subsamples of the initial soil sample. An a priori determined amount of highly concentrated nitrate solution is added to the first subsample and the ATR spectrum of this paste is used to estimate the sample water content. It is then possible to calculate the amount of water that should be added to the second subsample so that the resulting paste is very close to the ideal standard paste. Nitrate concentration, mg [N]/kg [dry soil], is estimated using the FT-IR/ATR spectrum of this second paste. Results are presented for a laboratory experiment with four agricultural soils, as well as for a field trial with a calcareous soil. For water content, the determination errors range from 0.01 to 0.02 g [water]/g [dry soil]. For nitrate concentration, the errors for three of the soils range from 5.9 to 8.4 mg [N]/kg [dry soil], while for the fourth, calcareous clay soil, the determination error is 13.6 mg [N]/kg [dry soil]. The determination errors obtained for the field trial are similar to the ones obtained for a similar soil under laboratory conditions, which shows the potential usefulness of the approach for improving N-application management and reducing environmental pollution.
Absorption Spectrometry by Narrowband Light in Optically Saturated and Optically Pumped Collision and Doppler Broadened Gaseous Media under Arbitrary Optical Thickness Conditions
Authors: Axner Ove , Schmidt Florian M. , Foltynowicz Aleksandra , Gustafsson Jörgen , Omenetto Nicoló , Winefordner James D.
Published: October 2009

This work examines absorption spectrometry by narrowband light in gaseous media with arbitrary optical thickness when the light induces optical saturation or optical pumping. Two quantities are defined: the observed absorbance, Aobs, and the true absorbance, Atrue. The former is the absorbance that is measured under the existing conditions, whereas the latter represents the absorbance one would measure if the light acted solely as a probe of the populations of the various levels, and it is therefore directly proportional to the concentration or density of absorbers. A general integral equation for the propagation of light in media of arbitrary optical thickness in which the light influences the populations of the levels involved is derived. This expression is transcendental in the observed absorbance and cannot be solved analytically. It is shown that an analytical expression can be derived by investigating the inverse relationship, i.e., Atrue = f ( Aobs). Inasmuch as collision and Doppler broadened media react differently to optical saturation, they are considered separately. It is shown that a nonlinear response results if the medium is optically saturated (or pumped) and not optically thin. Expressions for the error introduced if the technique of standard additions is uncritically applied to such a system are derived.
Time-Resolved Fourier Transform Infrared Spectroscopy of Chemical Reactions in Solution Using a Focal Plane Array Detector
Authors: Kaun N. , Vellekoop M. J. , Lendl B.
Published: October 2009

A Fourier transform infrared (FT-IR) microscope equipped with a single as well as a 64 × 64 element focal plane array MCT detector was used to measure chemical reaction taking place in a microstructured flow cell designed for time-resolved FT-IR spectroscopy. The flow cell allows transmission measurements through aqueous solutions and incorporates a microstructured mixing unit. This unit achieves lamination of the two input streams with a cross-section of 300 × 5 μm each, resulting in fast diffusion-controlled mixing of the two input streams. Microscopic measurement at defined positions along the outlet channel allows time-resolved information of the reaction taking place in the flow cell to be obtained. In this paper we show experimental results on the model reaction between formaldehyde and sulfite. Using the single-point MCT detector, high-quality FT-IR spectra could be obtained from a spot size of 80 × 200 μm whereas the FPA detector allowed recording light from an area of 260 × 260 μm focused on its 64 × 64 detector elements. Therefore, more closely spaced features could be discerned at the expense of a significantly lower signal-to-noise (S/N) ratio per spectrum. Multivariate curve resolution–alternating least squares was used to extract concentration profiles of the reacting species along the outlet channel axis.
Spectrofluorimetric Characterization of Mixed Nanoaggregates Comprising a Double-Chain Cationic Surfactant and a Cationic or Non-Ionic Single-Chain Surfactant
Authors: Del Burgo Patricia , Aicart Emilio , Junquera Elena
Published: October 2009

A series of mixed vesicle and pre-vesicle nanoaggregates, comprising a cationic double-chain surfactant (di-decyldimethylammonium bromide, di-C10DMAB, or di-dodecyldimethylammonium bromide, di-C12DMAB), and a cationic (dodecylethyldimethylammonium bromide, C12EDMAB) or non-ionic (octyl-β-D-glucopyranoside, OBG) single-chain surfactant have been characterized by means of steady-state fluorescence spectroscopy. For that purpose, the fluorescent emission of two probes, one anionic (TNS) and the other non-ionic (PRODAN), which is known to be sensitive to the polarity, rigidity, and/or microviscosity of the environment within which the probes are housed, has been measured in the presence of the above-mentioned mixed aggregates. The results of this analysis yield interesting information about the characteristics of the vesicle surface and bilayer, as well as about the existence of clusters and/or nanoaggregates prior to the formation of vesicles.
Analysis of Data Obtained from a Frequency-Multiplexed Phase-Modulation Fluorometer Using an Autoregressive Model
Authors: Iwata Tetsuo , Muneshige Akitaka , Araki Tsutomu
Published: October 2009

In order to derive plural values of fluorescence lifetimes simultaneously from a multi-component sample, we formulate a mathematical method for analyzing data obtained from a frequency-multiplexed phase-modulation fluorometer (FM-PMF) using an autoregressive (AR) model. Various parameter settings necessary for performing accurate data analysis based on the AR model are studied through numerical simulations. Measurement results of fluorescence lifetimes of real samples, 10 ppm quinine sulfate in 0.1 N H2SO4, 10 ppm rhodamine 6G in ethanol, and their mixture with a volume ratio of 1:1, demonstrate that the proposed method works quite well.
Study of Thermal Dynamics of Defatted Bovine Serum Albumin in D2O Solution by Fourier Transform Infrared Spectra and Evolving Factor Analysis
Authors: Yuan Bo , Murayama Koichi , Yan Huiming
Published: October 2009

Fourier transform infrared (FT-IR) spectra have been measured for defatted bovine serum albumin (BSA) in D2O with a concentration of 2.0 wt % over a temperature range of 26–90 °C and the corresponding difference spectra have been calculated by subtracting the contribution of D2O at the same temperature. Evolving factor analysis (EFA) by selecting two factors and three factors has been employed to analyze the temperature-dependent difference IR spectra in the 1700–1600 cm−1 spectral region of the defatted BSA in D2O solution. Three-factor EFA has been employed to determine the distinction of the three protein species involved in the process of temperature elevation: native, transitional, and denatured protein. The temperature profiles obtained from three-factor EFA indicate that heat-induced conformational change in the secondary structures of defatted BSA in D2O undergoes two two-state transitions, a drastic transition and a slight transition, which occur in the temperature ranges of 68–82 °C and 56–76 °C, respectively.
Accurate Myoglobin Oxygen Saturation by Optical Spectroscopy Measured in Blood-Perfused Rat Muscle
Authors: Arakaki Lorilee S. L. , Burns David H. , Kushmerick Martin J.
Published: October 2009

Optical spectra were acquired from myoglobin and hemoglobin solutions and from the tibialis anterior muscle of Sprague–Dawley rats in the visible region (515 to 660 nm). Validation studies were performed on the in vitro spectra to demonstrate that partial least squares analysis of second-derivative spectra yields accurate measurements of myoglobin saturation in the presence of varying hemoglobin concentrations and saturations. When hemoglobin concentrations were varied between 0.25 and 4 times that of myoglobin, myoglobin saturations were measured with a root mean squared error (RMSE) of 4.9% ( n = 56) over the full range from 0 to 1. Myoglobin saturations were also shown to be largely unaffected by hemoglobin saturation. RMSE values of only 1.7% ( n = 77) were found when hemoglobin saturations were varied independently from myoglobin saturations. These in vitro validation studies represent the most complete and rigorous done to date using partial least squares analysis on myoglobin and hemoglobin spectra. Analysis of reflectance spectra from the rat hind limb yielded accurate measures of volume-averaged myoglobin fractional saturation in the presence of hemoglobin in vivo. Hemodilution showed that myoglobin fractional saturation measurements in the rat leg are not sensitive to changes in hematocrit, thereby confirming the results from solutions in vitro. Decreases in optical density of 11.3 ± 3.0% (n = 3) were achieved while myoglobin saturation decreased by only 3.1 ± 3.8%. Myoglobin saturation was significantly increased when the fraction of inspired O2 was increased, showing that manipulations of myoglobin saturation are detectable and that myoglobin is not fully saturated in resting muscle. Together, these in vitro and in vivo studies show that cellular oxygenation derived from myoglobin fractional saturation can be measured accurately with little cross-talk from hemoglobin in the visible wavelength region, thereby extending optical spectroscopic studies of cellular and vascular oxygenation beyond the near-infrared regions previously studied.
Rapid, Nondestructive Near-Infrared Assay for Water in Sealed Dimethyl Sulfoxide Compound Repository Containers
Authors: Pelletier Michael J. , Fabiilli Mario L.
Published: October 2009

Water contamination in dimethyl sulfoxide (DMSO) compound libraries is a recognized problem in the pharmaceutical industry. We describe a nondestructive, near-infrared (NIR) assay for water contamination inside the sealed containers used for compound libraries. This assay does not require opening the containers. We also report our observation of the permeation of water from laboratory air through the sealed container and into the DMSO solution over a period of months, as well as the rate of water absorption by DMSO directly exposed to laboratory air.
Kinetics of Lisinopril Intramolecular Cyclization in Solid Phase Monitored by Fourier Transform Infrared Microscopy
Authors: Widjaja Effendi , Tan Wei Jian
Published: October 2009

The solid-state intramolecular cyclization of lisinopril to diketopiperazine was investigated by in situ Fourier transform infrared (FT-IR) microscopy. Using a controllable heating cell, the isothermal transformation was monitored in situ at 147.5, 150, 152.5, 155, and 157.5 °C. The collected time-dependent FT-IR spectra at each isothermal temperature were preprocessed and analyzed using a multivariate chemometric approach. The pure component spectra of the observable component (lisinopril and diketopiperazine) were resolved and their time-dependent relative contributions were also determined. Model-free and various model fitting methods were implemented in the kinetic analysis to estimate the activation energy of the intramolecular cyclization reaction. Arrhenius plots indicate that the activation energy is circa 327 kJ/mol.
Discriminant Analyzing System for Wood Wastes Using a Visible—Near-Infrared Chemometric Imaging Technique
Authors: Kobori Hikaru , Yonenobu Hitoshi , Noma Junichi , Tsuchikawa Satoru
Published: October 2009

A new optical system was developed and applied to automated separation of wood wastes, using a combined technique of visible–near-infrared (Vis-NIR) imaging analysis and chemometrics. Three kinds of typical wood wastes were used, i.e., non-treated, impregnated, and plastic-film overlaid wood. The classification model based on soft independent modeling of class analogy (SIMCA) was examined using the difference luminance brightness of a sample. Our newly developed system showed a good/promising performance in separation of wood wastes, with an average rate of correct separation of 89%. Hence, it is concluded that the system is efficiently feasible for online monitoring and separation of wood wastes in recycling mills.
On-Line Near-Infrared Spectrometer to Monitor Urea Removal in Real Time during Hemodialysis
Authors: Cho David S. , Olesberg Jonathon T. , Flanigan Michael J. , Arnold Mark A.
Published: October 2009

The ex vivo removal of urea during hemodialysis treatments is monitored in real time with a noninvasive near-infrared spectrometer. The spectrometer uses a temperature-controlled acousto optical tunable filter (AOFT) in conjunction with a thermoelectrically cooled extended wavelength InGaAs detector to provide spectra with a 20 cm−1 resolution over the combination region (4000–5000 cm−1) of the near-infrared spectrum. Spectra are signal averaged over 15 seconds to provide root mean square noise levels of 24 micro-absorbance units for 100% lines generated over the 4600–4500 cm−1 spectral range. Combination spectra of the spent dialysate stream are collected in real-time as a portion of this stream passes through a sample holder constructed from a 1.1 mm inner diameter tube of Teflon. Real-time spectra are collected during 17 individual dialysis sessions over a period of 10 days. Reference samples were extracted periodically during each session to generate 87 unique samples with corresponding reference concentrations for urea, glucose, lactate, and creatinine. A series of calibration models are generated for urea by using the partial least squares (PLS) algorithm and each model is optimized in terms of number of factors and spectral range. The best calibration model gives a standard error of prediction (SEP) of 0.30 mM based on a random splitting of spectra generated from all 87 reference samples collected across the 17 dialysis sessions. PLS models were also developed by using spectra collected in early sessions to predict urea concentrations from spectra collected in subsequent sessions. SEP values for these prospective models range from 0.37 mM to 0.52 mM. Although higher than when spectra are pooled from all 17 sessions, these prospective SEP values are acceptable for monitoring the hemodialysis process. Selectivity for urea is demonstrated and the selectivity properties of the PLS calibration models are characterized with a pure component selectivity analysis.
Two-Dimensional Correlation Analysis of Nuclear Magnetic Resonance Metabonomics Data
Authors: Šašić Slobodan
Published: October 2009

Two-dimensional (2D) correlation analysis has been used in this study to identify changes in complex nuclear magnetic resonance (NMR) metabonomics spectra of rat urine samples obtained during a study in which vasculitis (vascular injury), an important safety element in preclinical trials, was induced. Two types of correlation analysis were performed, along the variables and along the samples, and both 2D covariance and correlation coefficient maps were calculated. The binned and “raw” NMR spectra were analyzed (0.04 and 0.001 ppm resolution, respectively). Good correlation was found among the major peaks of the binned spectra, and two groups of samples were identified using sample–sample 2D correlation maps. Much more complex correlation features were obtained from the “raw” spectra, in which the specific, butterfly-like patterns were obtained in the covariance map but with only a few significant correlation coefficients in the corresponding 2D correlation maps. In terms of classification, the same group of the last nine spectra that indicated the end of the process and clustered in the 2D sample–sample covariance map of the binned data was also found in the 2D sample–sample covariance map of the raw NMR spectra but, again, not in the 2D correlation coefficient map. A discussion is given on the details of the application of the correlation analysis with regard to spectral data resolution, alignment, the effect of actual intensities of the NMR signal, and reference to various results from 2D correlation analysis of vibrational spectra.
Aleurone Cell Walls of Wheat Grain: High Spatial Resolution Investigation Using Synchrotron Infrared Microspectroscopy
Authors: Jamme F. , Robert P. , Bouchet B. , Saulnier L. , Dumas P. , Guillon F.
Published: October 2009

Infrared microspectroscopy and immunolabeling techniques were employed in order to obtain deeper insight into the biochemical nature of aleurone cell walls of wheat grain. The use of a synchrotron source, thanks to its intrinsic brightness, has provided unprecedented information at the level of a few micrometers and has allowed the discrimination of various polysaccharides in cell walls. The high spectral quality obtained in the small analyzed domain has been beneficial in estimating the relative proportions of β-glucan and arabinoxylan, through the use of principal component analysis (PCA). The highest amount of β-glucan is found in periclinal cell walls close to the starchy endosperm. The junction regions between aleurone cells are enriched in arabinoxylan. At the early stage of wheat grain development (271°D), the chemical composition along the cell walls is more heterogeneous than at the mature stage. Both synchrotron infrared microspectroscopy and immunolabeling experiments made it possible to reveal the spatial heterogeneity of the various chemical compositions of aleurone cell walls.
A New Method for the Time-Resolved Analysis of Structure and Orientation: Polarization Modulation Infrared Structural Absorbance Spectroscopy
Authors: Liang Yongri , Mauran Damien , Prud'Homme Robert E. , Pellerin Christian
Published: October 2009

Polarization modulation infrared linear dichroism (PM-IRLD) is often used for measurements of molecular orientation with high sensitivity and good time resolution. However, PM-IRLD is unable to provide the structural absorbance spectrum because it does not measure separately the parallel and perpendicular spectra. Here we propose a new method, named polarization modulation infrared structural absorbance spectroscopy (PM-IRSAS), to overcome this limitation of PM-IRLD. PM-IRSAS measures the dichroic difference and structural absorbance spectra simultaneously and, therefore, allows quantitative analysis of molecular orientation and conformation with 200 ms time resolution. The PM-IRSAS method was first validated through comparison with conventional polarized FT-IR spectroscopy using drawn polymer films. Second, it was demonstrated that the PM-IRSAS method can provide a quantitative analysis of dynamic orientation and conformation changes in PET films during deformation and crystallization processes.
Multivariate Analysis of Attenuated Total Reflection—Fourier Transform Infrared Spectroscopic Data to Confirm the Origin of Honeys
Authors: Hennessy Siobhán , Downey Gerard , O'Donnell Colm
Published: October 2009

Fourier transform infrared (FT-IR) spectroscopy and chemometrics were used to verify the origin of honey samples ( n = 150) from Europe and South America. Authentic honey samples were collected from five sources, namely unfiltered samples from Mexico in 2004, commercially filtered samples from Ireland and Argentina in 2004, commercially filtered samples from the Czech Republic in 2005 and 2006, and commercially filtered samples from Hungary in 2006. Samples were diluted with distilled water to a standard solids content (70° Brix) and their spectra (2500–12 500 nm) recorded at room temperature using an FT-IR spectrometer equipped with a germanium attenuated total reflection (ATR) accessory. First- and second-derivative and standard normal variate (SNV) data pretreatments were applied to the recorded spectra, which were analyzed using partial least squares (PLS) regression analysis, factorial discriminant analysis (FDA), and soft independent modeling of class analogy (SIMCA). In general, when an attenuated wavelength range (6800–11 500 nm) rather than the whole spectrum (2500–12 500 nm) was studied, higher correct classification rates were achieved. An overall correct classification of 93.3% was obtained for honeys by PLS discriminant analysis, while FDA techniques correctly classified 94.7% of honey samples. Correct classifications of up to 100% were achieved using SIMCA, but models describing some classes had very high false positive rates.
Fully Automated High-Performance Signal-to-Noise Ratio Enhancement Based on an Iterative Three-Point Zero-Order Savitzky—Golay Filter
Authors: Schulze H. Georg , Foist Rod B. , Ivanov Andre , Turner Robin F. B.
Published: October 2009

The automated processing of data from high-throughput and real-time collection procedures is becoming a pressing problem. Currently the focus is shifting to automated smoothing techniques where, unlike background subtraction techniques, very few methods exist. We have developed a filter based on the widely used and conceptually simple moving average method or zero-order Savitzky–Golay filter and its iterative relative, the Kolmogorov–Zurbenko filter. A crucial difference, however, between these filters and our implementation is that our fully automated smoothing filter requires no parameter specification or parameter optimization. Results are comparable to, or better than, Savitzky–Golay filters with optimized parameters and superior to the automated iterative median filter. Our approach, because it is based on the highly familiar moving average concept, is intuitive, fast, and straightforward to implement and should therefore be of immediate and considerable practical use in a wide variety of spectroscopy applications.
How to Deal with Some Spurious Fringes in Fourier Transform Infrared Spectrometers
Authors: Max Jean-Joseph , Chapados Camille
Published: October 2009

Faulty fringes coming from an infrared spectrometer may creep into a spectrum. Because these come from one faulty interferogram out of many used to obtain the spectrum, these may pass unnoticed. However, they cause some problems in the data treatment of factor analysis and other spectral analysis. We present a method for detecting the faulty fringes and give a simple method to eliminate them at the interferogram accumulation level.
High Precision in Raman Frequency Achieved Using Real-Time Calibration with a Neon Emission Line: Application to Three-Dimensional Stress Mapping Observations
Authors: Odake Shoko , Fukura Satoshi , Kagi Hiroyuki
Published: October 2009

A three-dimensional (3D) Raman mapping system with a real-time calibration function was developed for detecting stress distributions in solid materials from subtle frequency shifts in Raman spectra. An atomic emission line of neon at 918.3 cm−1 when excited at 514.5 nm was used as a wavenumber standard. An emission spectrum of neon and a Raman spectrum from a sample were introduced into a single polychromator using a bifurcated optical fiber. These two spectra were recorded simultaneously on a charge-coupled device (CCD) detector using double-track mode. Energy deviation induced by the fluctuation of laboratory temperature, etc., was removed effectively using the neon emission line. High stability during long measurements was achieved. By applying curve fitting, positions of the Raman line were determined with precision of about 0.05 cm−1. The present system was applied to measurements of residual pressure around mineral inclusions in a natural diamond: 3D stress mapping was achieved.
Use of Attenuated Total Reflection—Fourier Transform Infrared Spectroscopy to Measure Collagen Degradation in Historical Parchments
Authors: Gonzalez Lee , Wess Tim
Published: October 2009

Developing a noninvasive method to assess the degraded state of historical parchments is essential to providing the best possible care for these documents. The conformational changes observed when collagen molecules, the primary constituent of parchment, unfold have been analyzed using attenuated total reflection–Fourier transform infrared (ATR-FT-IR) spectroscopy and the nanoscopic structural changes have been analyzed using X-ray diffraction (XRD). The relationship between the results obtained from these techniques was studied using principal component analysis, where correlation was found. The extent of gelatinization of historical parchments has been assessed using ATR-FT-IR and XRD and the frequency shifts observed as collagen degrades into gelatin have been reported. These results indicate that collagen degradation can be measured noninvasively in parchment and demonstrate the utility of ATR-FT-IR spectroscopy as a method to investigate historical documents.
Glow-Discharge-Assisted Laser-Induced Breakdown Spectroscopy: Increased Sensitivity in Solid Analysis
Authors: Tereszchuk K. A. , Vadillo J. M. , Laserna J. J.
Published: October 2009

A glow discharge operating in steady-state and pulsed temporal conditions is used to excite the material previously excited by a pulsed laser ablation system. The system provides a simple means by which to potentially excite the material ablated by the incident laser pulse by taking advantage of enhanced collisional excitation. In this way, one can effectively reduce laser pulse energies below the excitation and ionization thresholds to potentially those required solely for laser ablation of the material, reducing sample damage and improving the lateral resolution. Several critical parameters such as the gas pressure, gas type, and discharge voltage were evaluated, demonstrating the potential of the technique for spatially resolved analysis. The new dual glow-discharge laser-induced breakdown spectroscopy (GD-LIBS) synchronous scheme provides significant signal enhancements when compared to LIBS or GD under identical conditions.
A Simple and Rapid Fluorimetric Method for Simultaneous Determination of Protoporphyrin IX and Zinc Protoporphyrin IX in Whole Blood
Authors: Zhou Pei-Chen , Huang Wei , Zhang Rong-Bin , Zou Zhe-Xiang , Luo He-Dong , Falih Ali Abbas , Li Yao-Qun
Published: October 2009

Derivative variable-angle synchronous fluorescence (DVASF) spectrometry improves the spectral resolution and selectivity of the fluorescence method. The feasibility of DVASF spectrometry for the simultaneous determination of protoporphyrin IX (PP) and zinc protoporphyrin IX (ZnPP) was investigated. PP and ZnPP were distinguished from each other simultaneously and rapidly by the DVASF method. The spectra were resolved well, and the two components were determined in a single scan, avoiding the spectral compensation factor for PP and chromatographic separation. The linear range of the calibration curve for PP was from 0.190 to 152 nmol/L and for ZnPP was from 0.383 to 230 nmol/L. The detection limits of PP and ZnPP were 0.098 nmol/L and 0.088 nmol/L, respectively. The within-run imprecision (RSD, n = 5) for PP was 4.1%, and for ZnPP was 4.2%. Mean recoveries (SD) of PP and ZnPP added to a blood sample were 86.4 (7.3)% and 72.9 (6.6)%, respectively. This method should be a potential tool in the rapid routine screening of large quantities of samples.
Near-Infrared Spectroscopic Investigation of the Hydrothermal Degradation Mechanism of Wood as an Analogue of Archaeological Objects. Part I: Softwood
Authors: Inagaki Tetsuya , Mitsui Katsuya , Tsuchikawa Satoru
Published: October 2009

The degradation mechanism of softwood due to the variation of strength was analyzed in conjunction with spectroscopy and chemometrics, where the sample was thermally treated with a steam atmosphere. Near-infrared (NIR) spectra, chemical composition, oven-dried density, equilibrium moisture content, compressive Young's modulus parallel to the grain, and cellulose crystallinity of artificially degraded hinoki cypresses as an analogue of archaeological objects were systematically measured. Partial least squares (PLS) regression analysis was employed to predict compressive Young's modulus using NIR spectra and some kinds of wood properties as independent variables. Good prediction models were obtained for both independent variables. The scores and the loading plots derived from PLS analysis were applied to consistently explain the mechanism of hydrothermal degradation. It was suggested that the variation of compressive Young's modulus with hydrothermal treatment was governed by two main components, that is, depolymerization of polysaccharides and variation of cellulose crystallinity.
An Optimization of Parameters for Application of a Laser-Induced Breakdown Spectroscopy Microprobe for the Analysis of Works of Art
Authors: Osticioli Iacopo , Wolf Martin , Anglos Demetrios
Published: October 2009

Laser-induced breakdown spectroscopy (LIBS) provides many advantages for analysis of works of art. Both qualitative and semi-quantitative information about the elemental composition of an object can be rapidly obtained using LIBS. The time of response is on the order of a few seconds and no sample preparation is required. The possibility of performing analysis in museums and archeological sites makes LIBS particularly important; the combination of laser ablation and analysis as encountered in LIBS provides means to effectively carry out depth profiling of samples. By combining the use of a microscope, the dimension of the spot of the laser used to carry out analysis can be reduced and the spatial resolution highly improved; in this way, a very small area of the sample (on the order of 10 μm) can be analyzed. The aim of this work is to investigate the best working conditions in order to obtain the least amount of material removal during analysis, and, at the same time, the best quality in the spectral response for rapid and reliable identification of the elemental composition of an object. First, investigations were undertaken using metal alloys; second, the optimized LIBS conditions were used for analysis of models of painting layers prepared in the laboratory. Finally, a painting cross-section and a 19th century painted icon were analyzed using the micro-LIBS setup.
Raman Mapping Using Advanced Line-Scanning Systems: Geological Applications
Authors: Bernard Sylvain , Beyssac Olivier , Benzerara Karim
Published: October 2009

By allowing nondestructive chemical and structural imaging of heterogeneous samples with a micrometer spatial resolution, Raman mapping offers unique capabilities for assessing the spatial distribution of both mineral and organic phases within geological samples. Recently developed line-scanning Raman mapping techniques have made it possible to acquire Raman maps over large, millimeter-sized, zones of interest owing to a drastic decrease of the data acquisition time without losing spatial or spectral resolution. The synchronization of charge-coupled device (CCD) measurements with x,y motorized stage displacement has allowed dynamic line-scanning Raman mapping to be even more efficient: total acquisition time may be reduced by a factor higher than 100 compared to point-by-point mapping. Using two chemically and texturally complex geological samples, a fossil megaspore in a metamorphic rock and aragonite-garnet intergrowths in an Eclogitic marble, we compare here two recent versions of line-scanning Raman mapping systems and discuss their respective advantages and disadvantages in terms of acquisition time, image quality, spatial and imaging resolutions, and signal-to-noise ratio. We show that line-scanning Raman mapping techniques are particularly suitable for the characterization of such samples, which are representative of the general complexity of geological samples.
Quantitative Determination of Pharmaceutical Drug Formulations by Near-Infrared Spectroscopic Imaging
Authors: Kolomiets O. , Hoffmann U. , Geladi P. , Siesler H. W.
Published: October 2009

Over the last decade Fourier transform infrared (FT-IR) and near-infrared (NIR) spectroscopic imaging with focal plane array (FPA) detectors have proved powerful techniques for the rapid visualization of samples by a combination of spectroscopic and spatial information. Using these methods, selected sample areas can be analyzed with reference to the identification and localization of chemical species by FT-IR spectroscopy in the transmission or attenuated total reflection (ATR) mode and by NIR spectroscopy in diffuse reflection with a lateral resolution in the micrometer range. The present communication focuses on the quantitative determination of the active ingredient composition of a solid drug formulation by NIR spectroscopic imaging with a focal plane array detector and the results obtained are compared to the quantitative data obtained by conservative light-fiber NIR spectroscopic diffuse reflection measurements with a single-element detector. The communication also addresses the issue of penetration depth of NIR radiation into the investigated solid material.
Statistical Modeling of Spatial Distortion in Hyperspectral Calibration
Authors: Lo Edisanter , Fountain Augustus W. , Ingram John
Published: October 2009

This paper describes a statistically based efficient algorithm for the laboratory spectral calibration of a low-resolution terrestrial hyperspectral imaging camera operating in the visible range. Didymium oxide is used as a wavelength standard. The observed periodic spatial distortion in the wavelength abscissa of the hypercube is removed automatically through statistical modeling and the calibration of the wavelength abscissa is determined using a numerical method. The performance and cost of this algorithm in removing the spatial distortion are assessed quantitatively.
Influences of Composition on Electroless Deposition of Silver Nanoparticles on Glass Substrates for Surface-Enhanced Raman Scattering Measurements
Authors: Cheng Min-Liang , Yang Jyisy
Published: October 2009

A silver-mirror reaction was used to prepare active substrates for surface-enhanced Raman scattering (SERS). Glass plates were surface treated with a thin layer of silver nanoparticles (Ag-NPs). The factors influencing the performance of the SERS substrates were systematically studied. Factors included concentrations, species of complexing agents, and reducing agents. p-Nitrothiophenol ( pNTP) was used to test the surfaces with Ag-NPs, with the observed signals used to compare the performance resulting from different reducing and complexing agents. The morphologies of the Ag-NPs formed by different reaction conditions were also examined by scanning electron microscope (SEM) and correlated with the SERS signals. Reducing agents included formaldehyde, sodium tartrate, and several carbohydrates. The results indicate that the use of glucose as a reducing agent produced the most suitable Ag-NPs for SERS measurements. Complexing agents of ammonia and ethyl amine offered the best performances. The optimal concentration of complexing agent was found to be approximately six times the concentration of silver ions. With a reaction time of 2 min, the optimized concentrations of glucose and silver nitrate were 0.5 M and 50 mM, respectively. In general, the enhancement factor was on the order of 105 to 106 for the substrates prepared in this work.
Portable Equipment for Luminescence Lifetime Measurements on Surfaces
Authors: Romani A. , Clementi C. , Miliani C. , Brunetti B. G. , Sgamellotti A. , Favaro G.
Published: October 2009

The prototype of a portable instrument, based on the time-correlated single-photon counting method, purposely assembled for in situ measurements of luminescence lifetimes on artwork surfaces, is here presented. Preliminary tests have been carried out using the portable instrument and the results have been compared with those obtained using a bench instrument. In this way we have proven that the prototype provides lifetime measurements with good precision. It is also shown that fluorescence lifetime determinations, coupled with steady-state fluorescence spectra, allow the distinguishing, on laboratory samples, of different red organic lakes having similar fluorescence spectra, achieving new boundaries in the nondestructive diagnosis of artwork materials. The first in situ application of the technique on an original work of art, The Book of Kells, held at Trinity College Library, Dublin, highlighted the diagnostic potential of coupled steady-state and time-resolved luminescence spectroscopy in the identification of organic colorants.
Development of Infrared Photothermal Deflection Spectroscopy (Mirage Effect) for Analysis of Condensed-Phase Aerosols Collected in a Micro-Orifice Uniform Deposit Impactor
Authors: Dada Oluwatosin O. , Bialkowski Stephen E.
Published: October 2009

The potential of mid-infrared photothermal deflection spectrometry for aerosol analysis is demonstrated. Ammonium nitrate aerosols are deposited on a flat substrate using a micro-orifice uniform deposit impactor (MOUDI). Photothermal spectroscopy with optical beam deflection (mirage effect) is used to detect deposited aerosols. Photothermal deflection from aerosols is measured by using pulsed infrared laser light to heat up aerosols collected on the substrate. The deflection signal is obtained by measuring the position of a spot from a beam of light as it passes near the heated surface. The results indicate non-rotating impaction as the preferred MOUDI impaction method. Energy-dependent photothermal measurement shows a linear relationship between signal and laser intensity, and no loss of signal with time is observed. The detection limit from the signal–mass curve is 7.31 ng. For 30 minutes collection time and 30 L/min flow rate of the impactor, the limit of detection in terms of aerosol mass concentration is 0.65 μgm−3.
Reaction Kinetics of Acetone Peroxide Formation and Structure Investigations Using Raman Spectroscopy and X-Ray Diffraction
Authors: Jensen L. , Mortensen P. M. , Trane R. , Harris P. , Berg R. W.
Published: October 2009

Triacetone triperoxide (TATP) has been prepared in order to study the effect of pH and temperature on the reaction kinetics. Raman spectra of liquid mixtures of acetone and hydrogen peroxide were recorded versus time throughout the experiments. The spectral data of the liquid phases indicate that at 25 °C the reaction between acetone and hydrogen peroxide proceeds to form intermediates within one day. Based on the assumption that a likely reaction path involves a sequence of reaction steps between acetone and hydrogen peroxide, calculations of Raman spectra were performed using a density functional theory (DFT)/Hartree–Fock approach. It was not possible from this to assess with certainty which intermediate products formed most extensively in an acetone/hydrogen peroxide mixture. However, it was concluded that the most likely reaction mixture is a mixture of the different intermediate products and that the rate determining step is the ring closure. The reaction rate of TATP formation was found to increase with temperature and with sulfuric acid additions to the acetone/hydrogen peroxide mixture. By correlation of the induction time of TATP crystallization against pH it was shown that the reaction rate is first order with respect to the H+ concentration. Raman spectra of the precipitates from mixtures were in agreement with previous studies done for TATP, except in one case in which a crystal crystallized at 343 K had a distinctly different Raman spectrum. Comparison with calculated spectra revealed that the crystal produced could be diacetone diperoxide (DADP) or tetraacetone tetraperoxide (TrATrP). Single crystal X-ray diffraction analyses revealed that the crystal crystallized at 343 K was DADP.
Noninvasive Mail Inspection System with Terahertz Radiation
Authors: Hoshina Hiromichi , Sasaki Yoshiaki , Hayashi Aya , Otani Chiko , Kawase Kodo
Published: October 2009

Using the high penetrability of the terahertz waves and the characteristic absorption spectra in this frequency range, we have built a noninvasive mail inspection system targeting drugs and explosives. The system is composed of two stages; in the first stage, the scattering of a continuous terahertz wave is used for selecting mail that contains concealed powder; in the second stage, the absorption spectrum of the suspicious mail is measured and the material is identified using a terahertz spectrum database. We evaluated the performance and the limits of the inspection system.
Multivariate Prediction of the Thermal-Induced Weak Interaction Changes of Poly(N-Isopropylacrylamide) Film by the Interconversion between Middle and Near-Infrared Spectra
Authors: Zhang Liping , Noda Isao , Wu Yuqing
Published: October 2009

The use of a novel spectral interconversion scheme to probe weak molecular interactions of a polymer system is reported. Based on the multivariate regression model using partial least squares (PLS), the thermally induced changes in the weak interaction of poly( n-isopropylacrylamide) (PNiPA) film was studied by the interconversion between mid-infrared (MIR) and near-infrared (NIR) spectra measured at temperatures between 40 and 220 °C. It was demonstrated that not only NIR spectra but also well-resolved MIR spectra of PNiPA film, either in narrow or wide spectral ranges, can be predicted from each other based on the proposed scheme. The thermally induced weak interaction changes of PNiPA, expressed as either the band shift or intensity changes at a specific region, can be probed properly. Meanwhile, the effect of several important factors such as the selected spectral range, correlation between the specific bands, and especially the multiple scattering corrections (MSC) on the accuracy of the spectral prediction were also investigated in detail. This study provides a novel method for the analysis of weak interactions in complex systems.
Fourier Transform Infrared Imaging Spectroscopy of the Diffusion Process of D2O into Polyamide 11
Authors: Wessel Elke , Vogel Christian , Siesler Heinz W.
Published: October 2009

Fourier transform infrared (FT-IR) spectroscopic imaging with focal plane array detectors has proved a powerful technique for rapid chemical visualization of samples, with a lateral resolution up to 10–15 μm in the transmission micro mode. In the present communication the application of this technique is described for the study of the diffusion of D2O into a polyamide 11 (PA11) film. Apart from the in situ visualization of the diffusion front propagation in the time-resolved FT-IR images, the type of diffusion and the diffusion coefficient of D2O in the investigated polyamide have been determined.
A Time-Resolved Infrared Vibrational Spectroscopic Study of the Photo-Dynamics of Crystalline Materials
Authors: Towrie Mike , Parker Anthony W. , Ronayne Kate L. , Bowes Katharine F. , Cole Jacqueline M. , Raithby Paul R. , Warren John E.
Published: October 2009

Time-resolved infrared vibrational spectroscopy is a structurally sensitive probe of the excited-state properties of matter. The technique has found many applications in the study of molecules in dilute solution phase but has rarely been applied to crystalline samples. We report on the use of a sensitive pump–probe time-resolved infrared spectrometer and sample handling techniques for studies of the ultrafast excited-state dynamics of crystalline materials. The charge transfer excited states of crystalline metal carbonyls and the proton transfer of dihydroxyquinones are presented and compared with the solution phase.
Classification of Heterogeneous Solids Using Infrared Hyperspectral Imaging
Authors: Rutlidge Helen T. , Reedy Brian J.
Published: October 2009

Methods were explored for the classification of heterogeneous powder mixtures using Fourier transform infrared (FT-IR) hyperspectral image data. The images collected were non-congruent, meaning that samples of the same mixture do not have the same spatial arrangements of their components in their images. In order to classify such images on a one-image-per-object basis, dimension reduction was carried out so as to produce a score or feature vector for each image that preserved information about the heterogeneity of the sample. These feature vectors were then classified using discriminant analysis (DA) or soft independent modeling of class analogy (SIMCA). The most successful approach was the use of a median-interquartile range “super-spectrum” as the feature vector representing each image; using principal component analysis (PCA) DA classification, 87.5% of training samples were correctly classified using leave-one-out cross-validation, and 100% of a test set were correctly classified. This compares with 52.5% and 72%, respectively, when single-point spectra were used to classify the samples.
Determination of the Thickness of Silazane-Based SiOx Coatings in the Submicrometer Range by Near-Infrared Reflection Spectroscopy
Authors: Scherzer Tom , Mirschel Gabriele , Heymann Katja , Prager Lutz , Buchmeiser Michael R.
Published: October 2009

The thickness of thin silica layers in the submicrometer range, i.e., between about 150 and 700 nm, was determined by near-infrared (NIR) reflection spectroscopy. Silica layers were prepared by spin-coating of perhydropolysilazane (PHPS) on silicon wafers or poly(ethylene terephthalate) (PET) foil and subsequent conversion of the PHPS into SiOx by vacuum ultraviolet (VUV) irradiation at 172 nm. Since the NIR spectra of the inorganic layers do not show overtone and combination bands, analysis is based on tiny differences in reflectance of samples provided with layers of different thicknesses. Quantitative investigations were carried out by use of chemometric approaches on the basis of the partial least squares (PLS) algorithm. Optimization of the chemometric models was achieved by systematic variation of the preprocessing of the spectra before application of the PLS regression. The root mean square error of prediction (RMSEP) and the coefficient of determination R2 were used for the evaluation of the various pretreatment strategies. Reference data for the calibration procedures were obtained by means of gravimetry. The maximum error for the determination of the thickness was estimated to be on the order of 20%. The method was used to monitor the homogeneity of the thickness of silica layers made by use of a pilot scale coating machine. Thickness profiles recorded by NIR spectroscopy showed clear differences between layers with uniform or non-uniform quality of the application. Moreover, a close correlation of the profiles with the average coating weights determined by gravimetry was found.