bluuebunny/crossref_metadata_2025 huggingface dataset:
Interaction between a Capacitor Electrolyte and γ-Aluminum Oxide Studied by Fourier Transform Infrared Spectroscopy
Authors: Száraz Ildikó , Forsling Willis
Published: October 2003

The interaction between γ-aluminum oxide and an ethylene glycol (EG) based capacitor electrolyte was investigated by Fourier transform infrared (FT-IR) spectroscopy. It was found that only a few ingredients of the electrolyte react with the oxide (azelaic acid, poly(1-vinyl-2-pyrrolidone) (PVP), and phosphoric acid); the others act as pH or conductivity buffers (boric acid, ammonia, and water). The adsorption of azelaic acid and PVP from the electrolyte was studied as a function of temperature, pH, and time, and the result was compared to the adsorption from model solutions of simpler composition. The influence of other components such as phosphoric acid both in the electrolyte and on the aluminum oxide was also investigated, as was the presence of water. At low pH and high temperature ( T ≥ 105 °C) the acid formed an ester with EG and this product adsorbed on the oxide surface. The PVP was attached to the adsorbed azelaic acid by hydrophobic interaction, which is pH independent. Ester formation was found to be catalyzed by other electrolyte ingredients like boric acid. At high pH, surface adsorption of azelaic acid occurs through a deprotonated species, which is mainly coordinated through outer-sphere complexation. At high temperature or after a long equilibration time, the surface of the alumina changed, resulting in less adsorption of the organic substances, independent of pH. This change is due to a selective adsorption of phosphate species from the electrolyte, which block active surface sites.
Molecular Composition and Orientation of Interstitial versus Surface Silicon Oxides for Si(111)/SiO2 and Si(100)/SiO2 Interfaces using FT-IR and X-ray Photoelectron Spectroscopies
Authors: Kandilioti Georgia , Siokou Angeliki , Papaefthimiou Vasiliki , Kennou Stella , Gregoriou Vasilis G.
Published: October 2003

This work represents a characterization study of silicon oxide on Si(111) and Si(100) surfaces intended for use as substrates in organic light-emitting diodes (OLEDs) on chip devices. Samples have been prepared using either native oxide formation or thermal oxidation, and they have also been treated for activation of hydroxyl groups on their surface. Both Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) have been used in order to understand the molecular orientation as well as the chemical composition of the various oxide types formed during these different oxidation processes. These spectroscopic studies reveal the formation of two different types of oxides on these substrates. The first type is a thin oxide layer on the surface, whereas the second type, called interstitial, is found deeper in the substrate. Specifically, it was found that the Si(100) substrate forms a randomly oriented interstitial oxide, whereas the presence of a lower quantity but more oriented interstitial oxide was found for the Si(111) substrate. In addition, we report for the first time the position of the impurity oxygen for Si(111) substrates at 1122 cm−1. Finally, in both Si(100) and Si(111) substrates, the thin (<15 Å) silicon oxide layers are oriented and appear to contain silicon atoms of similar oxidation states. In contrast, both the thicker surface film (100 Å) as well as the interstitial oxide produced by the thermal oxidation procedure show random orientation and relative uniformity. Overall these orientation studies clearly show that the formation process of surface oxides in different substrates clearly creates species that are oriented differently with respect to the surface.
FT-IR Microspectroscopic Study of Shot Formation in Melt-Blown Webs
Authors: Ko W. C. , Bresee R. R.
Published: October 2003

We used Fourier transform infrared (FT-IR) microspectroscopy to investigate the chemical nature of fibers and defects called “shot” in melt-blown webs. Spectral differences were observed and evaluated in light of known thermal and oxidative degradation reactions for conditions comparable to those we used for melt blowing. Three different isotactic polypropylene polymers were evaluated in terms of the amount of shot produced and the amount of oxidative degradation exhibited by fibers and shot particles from each polymer. Little oxidative degradation was observed in fibers and the amount of degradation in fibers varied little for the three polymers we evaluated. Substantially more degradation was observed in shot particles, and the amount of degradation varied among the three polymers. Compared to polymer bound for fibers, we concluded that high temperature and mechanical shear in the extruder may introduce more chain scission in polymer bound for shot particles. Autoxidation reactions may occur after melt exits the die, and our data indicated that more oxidative degradation occurred in polymer that became shot particles than polymer that became fibers. The most favorable site for oxidation seemed to be tertiary rather than methylene hydrogen. Overall, the thermal history of polymer that becomes shot particles may be significantly different than the thermal history of polymer that becomes fibers, and this difference may have influenced shot formation.
Effect on the Partial Least-Squares Prediction of Yarn Properties Combining Raman and Infrared Measurements and Applying Wavelength Selection
Authors: De Groot P. J. , Swierenga H. , Postma G. J. , Melssen W. J. , Buydens L. M. C.
Published: October 2003

The combination of Raman and infrared spectroscopy on the one hand and wavelength selection on the other hand is used to improve the partial least-squares (PLS) prediction of seven selected yarn properties. These properties are important for on-line quality control during production. From 71 yarn samples, the Raman and infrared spectra are measured and reference methods are used to determine the selected properties. Making separate PLS models for all yarn properties using the Raman and infrared spectra, prior to wavelength selection, reveals that Raman spectroscopy outperforms infrared spectroscopy. If wavelength selection is applied, the PLS prediction error decreases and the correlation coefficient increases for all properties. However, a substantial wavelength selection effect is present for the infrared spectra compared to the Raman spectra. For the infrared spectra, wavelength selection results in PLS prediction errors comparable with the prediction performance of the Raman spectra prior to wavelength selection. Concatenating the Raman and infrared spectra does not enhance the PLS prediction performance, not even after wavelength selection. It is concluded that an infrared spectrometer, combined with a wavelength selection procedure, can be used if no (suitable) Raman instrument is available.
Silver Clusters onto Nanosized Colloidal Silica as Novel Surface-Enhanced Raman Scattering Active Substrates
Authors: Muniz-Miranda Maurizio
Published: October 2003

A new method is proposed for obtaining surface-enhanced Raman scattering (SERS)-active substrates by photochemical reduction of silver nitrate onto colloidal silica. Transmission electron microscopy (TEM) and UV–visible absorption spectroscopy are employed to investigate the nanoscale structure of the materials. High quality SERS spectra are obtained from different organic ligands to check the efficiency of these substrates. A marked stability of the colloidal suspension is ensured by the scarce tendency of the Ag-doped silica particles to aggregate by either aging or adsorption of ligand.
Monitoring the Temperature of Dilute Aqueous Solutions Using Near-Infrared Water Absorption
Authors: Otal Eugenio H. , Iñón Fernando A. , Andrade Francisco J.
Published: October 2003

An alternative spectroscopic approach for monitoring the temperature of aqueous solutions is presented. The method is based upon the temperature-induced spectral changes undergone by the second overtone (around 960 nm) of the near-infrared (NIR) water absorption band. Single and multilinear regression analysis are tested in order to evaluate the predictive ability of temperature. A linear dependence is found when measurements are performed at a single wavelength, but a lower prediction error is obtained when multilinear models are applied. No matrix effects produced by moderately concentrated common dissolved ions are found in a broad range of pH. A signal-to-noise ratio allows a precision of 0.5 °C for temperature monitoring. A prediction error of 0.77 °C (single linear regression) and 0.25 °C (multilinear approach) are achieved in a range from 15 to 90 °C. Advantages in terms of instrumentation and data analysis required are discussed.
Near-Infrared Spectroscopic Monitoring of the Diffusion Process of Deuterium-Labeled Molecules in Wood. Part I: Softwood
Authors: Tsuchikawa Satoru , Siesler H. W.
Published: October 2003

The diffusion process of several molecules (D2O, n-butanol (OD) and t-butanol (OD)) in softwood (Sitka spruce) was investigated by means of a deuterium exchange method and Fourier transform near-infrared (FT-NIR) polarization spectroscopy. The location of OH groups in different states of order of cellulose in wood was clarified by analyzing the FT-NIR transmission spectra ranging from 7200 to 6000 cm−1. Four absorption bands were assigned to 2 × v(OH) absorptions of the amorphous regions, OH groups in semi-crystalline regions, and two types of intramolecular hydrogen-bonded OH groups in the crystalline regions, respectively. The saturation level of accessibility was very different for these absorption bands (i.e., 70–80, 60, and 40–50% for the amorphous, semi-crystalline, and crystalline regions, respectively). However, the saturation accessibilities for each absorption band varied little with molecular structure and geometry of the diffusants. The diffusion rate of D2O was much faster than that of n-butanol (OD) and t-butanol (OD) for all states of orders. The size effect of the butanols led to slight differences in the diffusive transport in the crystalline regions.
Fluorescence Microspectroscopy Technique for the Study of Intracellular Protoporphyrin IX Dynamics
Authors: Sudworth Caroline D. , Stringer Mark R. , Cruse-Sawyer Janet E. , Brown Stanley B.
Published: October 2003

We describe a technique designed to monitor the fluorescence dynamics of photosensitizers used in photodynamic therapy (PDT) at micrometer-scale locations within individual formalin-fixed cells. The accumulation of protoporphyrin IX (PpIX) within keratinocytes and fibroblasts, following incubation with 5-aminolaevulinic acid (ALA), is shown to be dependent upon both incubation time and cell proliferation status. Also, the process of photobleaching within these cells is demonstrated via the depletion in PpIX fluorescence emission during exposure to 532 nm light. All spectra show a progressive reduction of the 634 nm PpIX peak, following a biexponential decay that is consistent with a singlet oxygen mediated process. The rate of photobleaching, when plotted as a function of light dose, increases with reduced incident laser power. The generation of the hydroxyaldehyde-chlorin photoproduct (photoprotoporphyrin), as monitored by the increase in fluorescence emission centered on 672 nm, is also greatest when the lowest laser power is applied. When light is delivered in two fractions, PpIX fluorescence recovers during the dark period and there is an increase in bleaching rate at the onset of the second exposure. These results are qualitatively consistent with measurements performed in vivo, which demonstrate that the photodynamic dose is dependent upon fluence rate and oxygen status.
Two-Dimensional Imaging Biosensor for the Monitoring of Lactate Released from Brain Slices
Authors: Qhobosheane Monde , Liu Xiaojing , Gu Yunrong , Wu Donghai , Tan Weihong
Published: October 2003

Real-time monitoring of lactate release from brain slices has been studied with an optical two-dimensional (2D) imaging biosensor. The 2D biosensor is prepared by direct immobilization of lactate dehydrogenase (LDH) molecules onto a flat silica glass surface through a covalent binding mechanism. The biosensor is able to spatially differentiate lactate concentration variations with conventional optical microscopic spatial resolution. This biosensor has the capability to effectively detect lactate down to a concentration of 100 nM. The 2D biosensor responds uniformly with 2.5% RSD from pixel to pixel. With a 100 ms response time, this 2D biosensor has the capability of monitoring simultaneously many cells in one image. We have studied the impact of KCl on lactate release from brain slices. Clear differences have been observed in lactate release for different regions of the tissue. The real-time determination of the newly released lactate from the mouse brain slices clearly demonstrates the feasibility of monitoring lactate release from living specimens. The 2D biosensor will enable us to study cellular communications and possibly other biological processes that require simultaneous temporal and spatial resolution.
Fluorescence Line Narrowing Spectroscopy of Polycyclic Aromatic Hydrocarbons on Solid—Liquid Extraction Membranes
Authors: Bystol Adam J. , Campiglia Andres D.
Published: October 2003

The potential of solid–liquid extraction fluorescence line narrowing spectroscopy is evaluated for screening polycyclic aromatic hydrocarbons in aqueous samples. Octadecyl silica membranes are used with the dual purpose of sample preconcentration and solid substrate for spectroscopic measurements. 4.2 K fluorescence line narrowed spectra are directly recorded from the membrane with the aid of a fiber-optic probe. The experimental procedure is free from organic solvents and takes less than 5 min per sample. With 10 mL of water sample, the limits of detection are at the parts-per-billion level. Qualitative analysis is based on wavelength time matrices, which provide a unique format for compound identification based on spectral and lifetime data. The selectivity of this approach is demonstrated with the unambiguous determination of naphthalene in a heavily contaminated water sample.
Inductively Coupled Plasma Atomic Emission Spectrometry: An Efficient Tool for Precise Determination of Mg/Ca and Sr/Ca Ratios in Biocarbonates
Authors: Sun Yali , Sun Min
Published: October 2003

A method is developed to precisely determine Mg/Ca and Sr/Ca ratios in biocarbonates by inductively coupled plasma atomic emission spectrometry (ICP-AES). This method precision (RSD%) is 0.52% for Mg/Ca and 0.28% for Sr/Ca, respectively. The precision suggests that ICP-AES is satisfactory for supplying good quality Mg/Ca and Sr/Ca data of biocarbonates for paleo-reconstruction. This ICP-AES technique was applied to 51 continuous coral sub-samples, and the results show annually periodical variations in coral Mg/Ca and Sr/Ca ratios, which are consistent with previous findings.
Laser-Enhanced Ionization with Avalanche Amplification: Detection of Cesium at fg/mL Levels
Authors: Temirov J. P. , Matveev O. I. , Smith B. W. , Winefordner J. D.
Published: October 2003

The avalanche amplification of the laser-enhanced ionization signal of Cs atoms in a flame has been studied. Ionization of Cs atoms, enhanced by two-step excitation, was detected in hydrogen and propane flames. By employing the effect of avalanche amplification of electrons, high signal-to-noise ratio (∼104) was obtained for a 100 ppt Cs solution. The extrapolated limit of detection was 30 fg/mL (ppq).
Potential for Using a Digital Micromirror Device as a Signal Multiplexer in Visible Spectroscopy
Authors: Spudich Thomas M. , Utz Charles K. , Kuntz Jennifer M. , Deverse Richard A. , Hammaker Robert M. , McCurdy David L.
Published: October 2003

A digital micromirror device (DMD™) was tested to demonstrate its potential as a multiplexing device for the simultaneous detection of visible electromagnetic radiation. Using a Visual Basic program, four sections of the DMD were illuminated by a light source and each region of mirrors was modulated at different low frequencies (14.92, 20.00, 25.00, and 34.48 Hz). A time-domain, multiplexed signal was collected from the sectors and a Fourier transform was performed on these data. The resulting frequency-domain spectrum showed that signal intensities correlated well with what was expected. Three different times were used to establish the best frequency resolution. Using this calculated frequency resolution, a 16-s scan could allow simultaneous detection of up to 240 emission/absorption wavelengths. Data collected also shows the selectivity of micromirror regions and the ability to choose specific regions of the micromirror plane, which could be valuable for a number of spectroscopic techniques.
Laser Plasma Spectroscopy of Al-Cu-Fe Quasicrystal and Alloy
Authors: Satta M. , Zeng X. , Mao X. , Mao S. S. , Russo R. E. , Giardini A. , Mele A.
Published: October 2003

Electron number density and temperature were determined from laser-induced plasmas produced by irradiating Al-Cu-Fe targets of a quasicrystal and of an alloy of similar composition. The Al(I) atomic emission spectra of the two systems were measured as a function of the distance from the target and of the time delay after laser irradiation. Differences of plasma characteristics were observed for laser ablation of quasicrystal and alloy targets, and the results were interpreted on the basis of different plasma formation mechanisms for the two systems.
Mars Analysis by Laser-Induced Breakdown Spectroscopy (MALIS): Influence of Mars Atmosphere on Plasma Emission and Study of Factors Influencing Plasma Emission with the Use of Doehlert Designs
Authors: Brennetot R. , Lacour J. L. , Vors E. , Rivoallan A. , Vailhen D. , Maurice S.
Published: October 2003

A project called MALIS (Mars Analysis by Laser-Induced breakdown Spectroscopy) is under progress to perform in situ analysis of Mars soils and rocks. This paper reports on the behavior of plasma in Martian conditions, i.e., in a CO2 atmosphere at pressures between 5 and 12 mbar. Plasma expansion and lifetime have been studied in order to compare plasma evolution under standard conditions (air at atmospheric pressure) and in a Mars atmosphere. We have shown that the Mars environment favors plasma expansion and lifetime. The second part of the study concerns optimization of the emission signal from the plasma. An original approach has been chosen, as we used a Doehlert design for the first time in laser-induced breakdown spectroscopy (LIBS). The best conditions obtained are for a laser wavelength of 1064 nm with the maximum energy available due to space limitations, which is 40 mJ at 15 Hz. The other factors studied are delay, angle of incidence, and CO2 pressure. We have shown that these factors do not have the same influence depending on which spectroscopic line is used, i.e., the atomic line or the ionic line.
Study of Fitting Algorithms Applied to Simultaneous Analysis of Large Numbers of Peaks in γ-ray Spectra
Authors: Morháč M. , Kliman J. , Jandel M. , Krupa Ľ. , Matousek V.
Published: October 2003

In this paper several nonlinear fitting algorithms without matrix inversion are proposed and investigated. The fitting algorithms represent an integral part of the analysis procedure, allowing us to simultaneously process large numbers of peaks in large blocks of data. The algorithms were applied to the analysis of both one-dimensional as well as two-fold coincidence γ-ray spectra. The properties of the proposed methods and the suitability of employing the appropriate algorithms to different kinds of γ-ray spectra were studied.
Effects of Particle Size and Laser-Induced Heating on the Raman Spectra of Alpha Quartz Grains
Authors: Chio Chi Hong , Sharma Shiv K. , Lucey Paul G. , Muenow David W.
Published: October 2003

Raman spectra of α-quartz (Qz) grains of various size (250 μm to <11 μm) and arrangement (individual and aggregated) have been investigated with a combination of confocal Raman and micro-Raman systems. Frequency downshift and line broadening of the 464 cm−1, vs(Si–O–Si) band are observed in the smallest size group (<11 μm, both individual grains and aggregates) because of laser-induced heating and are used to estimate the temperature of the sampled region. The intensity ratio of the anti-Stokes to Stokes Raman lines is also used to estimate the vibrational temperature of the samples under different excitation power. The degree of laser-induced heating is more noticeable in the aggregates than in the individual grains with the use of medium-level laser excitation (≤150 mW). Heating diminishes with increasing grain size, and it can only be detected in grain aggregates between 11 and 20 μm in diameter using 150 mW excitation. Intensity studies of the vs(Si–O–Si) band using individual grains show no noticeable signs of grain size effects. However, grain size effects become an important factor in the study of aggregates in which spectral intensity diminishes with respect to decreasing grain size.
Exploitation of Friedel—Crafts Acylation as a Color Derivatizing Reaction for Terpene and Lipids Analyses
Authors: Studer Joe , Purdie Neil , Krouse Justin
Published: October 2003

Rapid Friedel–Crafts chromogenic acylations of alkene groups at ambient temperatures are shown to be successful selective procedures for discriminating among a group of natural products, twelve of which are structurally related low molecular weight hydrocarbons that include nine terpenoids, and nineteen unsaturated and polyunsaturated fatty acid esters. The procedure has all the properties needed of a rapid, routine assay for use as a quality control test reagent for standard reference materials and natural oils, for on-line analyses during their commercial processing, and the potential for applications in the analyses of multicomponent mixtures without the need for prior separation.
Friedel—Crafts Acylation as a Quality Control Assay for Steroids
Authors: Studer Joe , Purdie Neil , Krouse Justin A.
Published: October 2003

The rapid Friedel–Crafts chromogenic acylation of alkene groups at ambient temperatures using a 25:1 mixture of 98% acetyl chloride and 70% perchloric acid is shown to have all the properties needed to serve as a potential quality control reagent that can be used to routinely discriminate among steroid analogs. Although ostensibly a non-selective reagent, from these and prior applications on terpenes and polyunsaturated acid esters, it is seen that the reaction is capable of discriminating bewteen geometric isomers and even enantiomers. The selectivity towards acylation of the α- over the β-position at C-17 makes the method adaptable to screening for anabolic steroids. Reactions at that position produce the more unusual results, including a positive color reaction for α-methyltestosterone even though there is no alkene functional group in the vicinity of C-17. For molecules with more than one alkene, concurrent acylations are independent one from the other and, in the absence of any interferences, their spectral properties are found to be additive.
Determination of Enantiomeric Excess Using the Ultraviolet—Circular Dichroism and the High-Performance Liquid Chromatography—Circular Dichroism Methods
Authors: Chen Li , Zhao Yanjun , Gao Feng , Garland Marc
Published: October 2003

Two useful numerical methods using ultraviolet (UV) and circular dichroism (CD) spectroscopies are proposed to determine enantiomeric excess (e.e). An algorithm is also proposed to generate self-consistent pure R and S enantiomer reference spectra. After all pure reference spectra are generated, a simulated annealing algorithm is applied to minimize the mismatch between the experimental spectra and the spectra after a least-squares fit. Optimal factors for R and S enantiomers are then used to determine e.e. The ultraviolet–circular dichroism (UV-CD) method uses the combined UV and CD spectra in a composite form, while the high-performance liquid chromatography (HPLC)-CD method only employs the CD spectra with the total concentrations of R plus S enantiomers provided by HPLC using a non-chiral stationary phase. Both methods were successfully tested on mixtures with known composition and then applied to real experimental data (unknown compositions). Compared with the UV-CD method, the results show that excellent results are more readily obtained using the HPLC-CD method. With the systems studied, the latter usually provided outstanding estimations of e.e with low error percentages.
Investigation of Asphaltene Association by Front-Face Fluorescence Spectroscopy
Authors: Albuquerque Flávio Cortiñas , Nicodem David E. , Rajagopal Krishnaswamy
Published: October 2003

The tendency of asphaltenes to aggregate and form clusters in solvents was studied by fluorescence spectroscopy. This was done by evaluating the relative fluorescence quantum yield of asphaltenes diluted at several concentrations in toluene and by studying the changes in the fluorescence spectra of asphaltene solutions as the composition of the solvent, toluene and cyclohexane, is changed. The asphaltene fraction (heptane insoluble) was collected from a Brazilian heavy crude oil, and solutions of this material varying from 0.016 g/L up to 10 g/L were prepared in toluene. Front-face emission spectra were obtained in two wavelength ranges, from 310 to 710 nm, excited at 300 nm (short range), and from 410 to 710 nm, excited at 400 nm (long range). Severe quenching was observed at concentrations above about 0.1 g/L. Stern–Volmer plots (reciprocal of quantum yield against concentration) exhibited nonlinear, downward-curved behavior, indicating that a more complex suppression mechanism, probably influenced by the association of the asphaltene molecules, is taking place. The same asphaltenes were dissolved (0.1 g/L) in binary mixtures of toluene and cyclohexane, and emission spectra in both the short range and long range were obtained. Fluorescence was progressively quenched at longer wavelengths of the spectra as the proportion of cyclohexane in the solvent grew. Cyclohexane, a poor asphaltene solvent, is probably inducing static quenching through association of asphaltenes.
Multi-Wavelength Mid-Infrared Micro-Spectral Imaging Using Semiconductor Lasers
Authors: Guo B. , Wang Y. , Peng C. , Luo G. P. , Le H. Q.
Published: October 2003

Infrared (IR, 3–12-μm) microscopic spectral imaging is an important analytical technique. Many current instruments employ thermal IR light sources, which suffer the problem of low brightness and high noise. This paper evaluates the system engineering merit in using semiconductor lasers, which offer orders-of-magnitudehigher power, brightness, and lower noise. A microscopic spectral imaging system using semiconductor lasers (quantum cascade) as illuminators, and focal plane array detectors demonstrated a high signal-to-noise ratio (>20 dB) at video frame rate for a large illuminated area. The comparative advantages of laser vs. thermal light source are analyzed and demonstrated. Microscopic spectral imaging with fixed-wavelength and tunable lasers of 4.6-, 5.1-, 6-, and 9.3-μm wavelength was applied to a number of representative samples that consist of biological tissues (plant and animal), solid material (a stack of laminated polymers), and liquid chemical (benzene). Transmission spectral images with ∼30-dB dynamic range were obtained with clear evidence of spectral features for different samples. The potential of more advanced systems with a wide coverage of spectral bands is discussed.
Specific Interactions Study in Complexes of Poly(Mono-n-Alkyl Itaconates) with Tertiary Polyamides
Authors: Katime Issa , Meaurio Emilio , Cesteros Luis C. , Mendizábal Eduardo
Published: October 2003

This paper reports an FT-IR study of blends of poly(mono-n-alkyl itaconates) with poly(N,N-dimethylacrylamide) (PDMA) and poly(ethyloxazoline) (PEOX). Strong hydrogen bonding has been found, and both polybases have shown similar acceptor strengths. Derivative techniques show asymmetric profiles for the free carbonyl band of the polybases, resulting in shifted band locations. The extent of the interassociation has been estimated by spectral curve fitting of the polybase carbonyl band. The results show that the interaction degree in blends with PEOX does not depend on the length of the poly(monoalkyl itaconate) side group, while an inter-associating ability loss is observed in blends with PDMA as the side-group size of the polyacid increases. This different behavior is attributed to the greater interspacing between vicinal carbonyl groups in PEOX. This band shows conformational sensitivity and reflects the conformational changes that occur as the steric hindrances present in the medium (due to the bulky side groups of the polyacids) increase.
FT-IR Spectroscopic Analysis of Rainbow Trout Liver Exposed to Nonylphenol
Authors: Çakmak Gülgün , Togan Inci , Uğuz Cevdet , Severcan Feride
Published: October 2003

Nonylphenol (NP) is a biodegradation product of nonylphenol ethoxylates (NPEs) belonging to the alkylphenol ethoxylates (APEs) group. APEs are widely used nonionic surfactants in detergents, herbicides, pesticides, paints, and cosmetics. The present work investigates the effects of NP on rainbow trout ( Oncorhynchus mykiss) livers at the molecular level using Fourier transform infrared (FT-IR) spectroscopy. The FT-IR spectra revealed dramatic differences between the NP-treated and control tissues, which mainly indicated that the level of triglycerides increased, the lipid order increased, and the protein concentration decreased in the treated samples. Moreover, it was also found that glycogen levels significantly decreased and the relative content of nucleic acids increased in NP-treated fish. The 17β-Estradiol-treated fish liver spectra were found to be quite similar to those of NP-treated fish. All these results implied that rainbow trout may offer considerable promise to be used as a bioindicator for NP in the future.
New Approach to Generalized Two-Dimensional Correlation Spectroscopy. IV: Eigenvalue Manipulation Transformation (EMT) for Partial Attenuation of Dominant Factors
Authors: Jung Young Mee , Kim Seung Bin , Noda Isao
Published: October 2003

This paper extends our previous work on the potential of eigenvalue manipulating transformation (EMT) of a data matrix for spectral selectivity enhancement in two-dimensional (2D) correlation analysis. EMT operation by uniformly lowering the power of a set of eigenvalues associated with the original data exaggerates the information content of minor principal components and reduces that of major principal components. Thus, much more subtle differences of spectral behavior for each component are now highlighted. Similarly, the selective truncation of dominant principal component (PC) factors to bring up the subtle contributions of minor factors is also considered. The EMT-reconstructed data matrix where power parameter m is negative greatly reduces the contribution of the first PC. Hybrid models for the attenuation of the contribution of the first PC are discussed. Synchronous 2D correlation spectra from PC1-attenuated data matrix A** obtained by varying the value of the attenuation parameter k show a much more profound effect than asynchronous 2D correlation spectra. As the value of k is increased, features of 2D correlation spectra start looking very much like those from the principle component analysis (PCA)-reconstructed data with only the second and third PCs and from the EMT-reconstructed data matrix where the power parameter m is negative.
Spectral Code Index (SPECOIND): A General Infrared Spectral Database Search Method
Authors: Li Jian Feng , Fan Bo Tao , Doucet Jean-Pierre , Panaye Annick
Published: October 2003

A new spectral code that can be used by Relational Database Management Systems (RDBMS) as an index for infrared (IR) spectra searches in Relational Database (RDB) is presented and its suitability is evaluated. Spectral codes are constructed for all spectra in the database as the spectral indexes and three query strings are created with the same theory used for the creation of the index code for the query spectrum. Some effects of parameters used to create index strings and query strings are discussed. All spectral searches are accomplished in structured query language (SQL) approach and the utilization examples of SQL have been shown. The sequential application of this procedure can reduce the original library of about 18 000 spectra to a few spectra that can be used as references for subsequent detailed comparison. The software developed for the proposed system is particularly suitable for spectral search and structure interpretation.
Identification of Bacterial Spores Using Statistical Analysis of Fourier Transform Infrared Photoacoustic Spectroscopy Data
Authors: Thompson Sandra E. , Foster Nancy S. , Johnson Timothy J. , Valentine Nancy B. , Amonette James E.
Published: October 2003

Fourier transform infrared photoacoustic spectroscopy (FTIR-PAS) has been applied for the first time to the identification and speciation of bacterial spores. A total of forty specimens representing five strains of Bacillus spores ( Bacillus subtilis ATCC 49760, Bacillus atrophaeus ATCC 49337, Bacillus subtilis 6051, Bacillus thuringiensis subsp. kurstaki, and Bacillus globigii Dugway) were analyzed. Spores were deposited, with minimal preparation, into the photoacoustic sample cup and their spectra recorded. Principal component analysis (PCA), classification and regression trees (CART), and Mahalanobis distance calculations were used on this spectral library to develop algorithms for step-wise classification at three levels: (1) bacterial/nonbacterial, (2) membership within the spore library, and (3) bacterial strain. Internal cross-validation studies on library spectra yielded classification success rates of 87% or better at each of these three levels. Analysis of fifteen blind samples, which included five samples of spores already in the spectral library, two samples of closely related Bacillus globigii 01 spores not in the library, and eight samples of nonbacterial materials, yielded 100% accuracy in distinguishing among bacterial/nonbacterial samples, membership in the library, and bacterial strains within the library.
External Cavity Diode Laser Based Photoacoustic Detection of CO2 at 1.43 μm: The Effect of Molecular Relaxation
Authors: Veres Anikó , Bozóki Zoltán , Mohácsi Árpád , Szakáll Miklós , Szabó Gábor
Published: October 2003

Photoacoustic spectroscopy, based on an external cavity diode laser operating at 1431 nm, was used for measuring CO2 concentration as a minority component in a gas mixture. By using N2 as a buffer gas, a molecular relaxation effect was observed, which influenced both the amplitude and the phase of the measured photoacoustic signal and consequently reduced the sensitivity of the PA system. This molecular relaxation effect could be suppressed by adding water vapor of a constant and relatively high (∼4%) concentration to the gas sample. In parallel with this, the arising spectral interference between H2O and CO2 necessitated the development of a simple yet efficient signal analysis method, which increased the sensitivity of the system by more than one order of magnitude and accordingly reduced the minimum detectable CO2 concentration down to ∼1000 ppm.
Gas-Phase Detection of Trinitrotoluene Utilizing a Solid-Phase Antibody Immobilized on a Gold Film by Means of Surface Plasmon Resonance Spectroscopy
Authors: Bowen J. , Noe L. J. , Sullivan B. P. , Morris K. , Martin V. , Donnelly G.
Published: October 2003

A multilayered biosensor was constructed and found to detect trinitrotoluene (TNT) in ppb concentrations in air both prior to and after detonation of TNT without use of a liquid phosphate buffered saline (PBS) superstrate. The biosensor surface was fabricated from a monoclonal antibody for TNT covalently bound to an 11,11′-dithio-bis(succinimidoylundecanoate) (DSU) self-assembled monolayer immobilized on a thin gold film bonded to a BK7 glass slide. The binding between the immobilized antibody and TNT antigen was detected using surface plasmon resonance spectroscopy (SPRS). Biosensor specificity for TNT was demonstrated with chemical homologues as well as against an unrelated explosive, RDX.
Reflectometric Study of Contaminant Layer on a Probe Window
Authors: Soetedjo Hariyadi , Räty Jukka
Published: October 2003

In this study properties of a contaminant material on the surface of a probe window (prism) were investigated. The probe window, i.e., the prism, is part of the reflectometer apparatus exploited in this study. The contaminant layer was considered to originate from a pulping solution containing lignin contacting the surface of the prism. In these experiments the contact time was up to 5.0 hours. To find the values of the contaminant material properties, i.e., refractive index ( n), extinction coefficient ( k), and effective thickness ( d), an optical model was proposed assuming that the contaminant layer is continuous and homogenous. In addition, the model includes an inter-diffusion layer existing between the contaminant layer and the lignin solution. From the fitting procedure using the optical model of depth profiling, it was found that the growth rate of the contaminant layer was approximately 60 nm per hour. The results obtained by theory and experiments were consistent for both s- and p-polarizations and for the various wavelengths of the light source (300, 400, and 500 nm).
True Chemical Composition Profiles at Polymer Interphases: Recovery from Measurements Distorted by Instrumental Broadening
Authors: Tomba Pablo , Eliçabe Guillermo
Published: October 2003

The determination of chemical composition profiles at polymer interphases is an important issue at the moment of elucidating the physical mechanisms that operate in polymer diffusion processes and for calculating diffusion parameters. Several techniques are available to measure these profiles, the most common being forward recoil spectroscopy, Rutherford backscattering spectrometry, nuclear reaction analysis, confocal Raman microspectroscopy (CRM), and scanning infrared microscopy. However, all these techniques are affected by the limited resolution of the experimental setup, which in practice produces a rounding effect on the sharp corners of the composition profile; this may lead to incorrect conclusions regarding the measurements. In this work an inverse technique is proposed to correct this undesirable effect in the profiles. The inversion is performed on a model of the measuring process, which includes the instrumental broadening function, a quantitative representation of the limited resolution. The proposed methodology was tested using numerically generated experiments and genuine experimental runs obtained from CRM measurements at interphases of polymer bilayers. In all cases, the recovered profiles were close to the expected ones. In the truly experimental results diffusion tails are observed behind and ahead of the diffusion front before the numerical treatment of the data. These tails may be caused by a genuine mass diffusion or by an artifact. After the numerical treatment the tails disappear and a sharp interphase is recovered, a result one expects for the polymer pairs under study.
Quantitative Analysis of Polyethylene Blends by Fourier Transform Infrared Spectroscopy
Authors: Cran Marlene J. , Bigger Stephen W.
Published: October 2003

The quantitative analysis of binary polyethylene (PE) blends by Fourier transform infrared (FT-IR) spectroscopy has been achieved based on the ratio of two absorbance peaks in an FT-IR spectrum. The frequencies for the absorbance ratio are selected based on structural entities of the PE components in the blend. A linear relationship between the absorbance ratio and the blend composition was found to exist if one of the absorbance peaks is distinct to one of the components and the other peak is common to both components. It was also found that any peak resulting from short-chain branching in copolymers (such as linear low-density polyethylene (LLDPE) or metallocene-catalyzed LLDPE (mLLDPE)), is suitable for use as the peak that is designated as being distinct to that component. In order to optimize the linearity of the equation, however, the selection of the second common peak is the most important and depends on the blend system studied. Indeed, under certain circumstances peaks that are not spectrally distinct can be used successfully to apply the method. The method exhibits potential for the routine analysis of PE blends that have been calibrated prior to its application.
Two-Dimensional Infrared Spectroscopy and Principal Component Analysis Studies on a New Azobenzene Derivative Supramolecular System Based on Hydrogen Bonds
Authors: Wu Yuqing , Hao Ya-Qiong , Li Min , Guo Chaowei , Ozaki Yukihiro
Published: October 2003

Infrared (IR) spectra of a supramolecular assembly with an azobenzene derivative and intermolecular hydrogen bonds have been measured in the temperature range from 30 to 200 °C to investigate heat-induced structural changes and thermal stability. Principal component analysis (PCA) and two kinds of two-dimensional (2D) correlation spectroscopy, variable–variable (VV) 2D and sample–sample (SS) 2D spectroscopy, have been employed to analyze the observed temperature-dependent spectral variations. The PCA and SS 2D correlation analyses have demonstrated that the complete decoupling of hydrogen bonds in the supramolecular assembly occurs between 110 and 115 °C, which is in good agreement with the results of a differential scanning calorimetry (DSC) study for the heating process. The PCA of the IR spectra in the region of 3600–3100 cm−1 has illustrated that there are at least four principal components for the different NH2 and CONH species in the present supramolecular system. The VV 2D correlation spectroscopy study has provided information about the structure and strength of hydrogen bonds of NH2 and CONH groups and their temperature-dependent variations. The different species of hydrogen-bonded NH2 and CONH groups in the supramolecular system can be clarified by the VV 2D correlation analysis. The VV 2D correlation analysis has also revealed the specific order of the temperature-induced changes in the hydrogen bonds of NH2 and CONH groups.
Characterization of Tetrol I-1 and (±)-anti-BPDE-DNA Adducts with Solid-Matrix Fluorescence Quenching
Authors: Smith Barry W. , Hurtubise Robert J.
Published: October 2003

The solid-matrix fluorescence (SMF) quenching of (±)-anti-benzo[a]pyrene-trans-7,8-dihydrodiol-9,10-epoxide (BPDE)-DNA adducts and a hydrolysis product of the DNA adducts, tetrol I-1, were investigated by using thallium nitrate and sodium iodide to quench the SMF. Several fluorescence quenching models were evaluated for both (±)-anti-BPDE-DNA adducts and tetrol I-1. The SMF quenching phenomena were quite different with the two salts for the (±)-anti-BPDE-DNA adducts and tetrol I-1. Generally, with thallium nitrate as a quencher, a two-site model with two independent quenching sites was applicable to both the (±)-anti-BPDE-DNA adducts and tetrol I-1 data. However, with sodium iodide, the SMF quenching data for tetrol I-1 were fit to the sphere of action model, but the (±)-anti-BPDE-DNA adducts SMF quenching data were qualitatively related to a BET isotherm. From the SMF quenching data, unique information was acquired for the quasi-intercalated BPDE-DNA adducts and the external form of the BPDE-DNA adducts. In addition, insights were obtained on how the adsorbed salts interacted with the solid matrix and with the (±)-anti-BPDE-DNA adducts and tetrol I-1.
Speciation of New Tri- and Tetra-Glucoconjugated Tetrapyrrolic Macrocycles (Porphyrins and Chlorins): An Electronic Molecular Spectroscopy Study
Authors: Desroches Marie-Catherine , Layac Sandrine , Prognon Patrice , Maillard Philippe , Grierson David S. , Curis Emmanuel , Nicolis Ioannis , Kasselouri Athena
Published: October 2003

In this work, we study the physicochemical properties of some newly developed glycoconjugated photosensitizers that can be used in photodynamic therapy (PDT) of cancers: meso-tri-and tetra-( meta-O-β-d-glucosyloxyphenyl)porphyrins and meso-, tri-, and tetra-( meta-O-β-d-glucosyloxyphenyl)chlorins. Their properties are compared to the non-glycosylated hydroxylated parent compounds meso-tetra-( meta-hydroxyphenyl) porphyrin and meso-tetra-( meta-hydroxyphenyl)chlorin. It was found that at the ground state, all porphyrins present, independent of the substitution, have the same mean ionization constant (pKa = 2.7), corresponding to two indistiguishable steps of protonation of tetrapyrrolic nitrogens. On the other hand, in the case of chlorins, one proton process can be observed and the corresponding nitrogen exhibits a slightly superior basicity (pKa = 3.0) with respect to porphyrins. Hydroxylated compounds present a second transition at high pH corresponding to the ionization of phenol groups (pKa = 10.5). Consequently, all photosensitizers are not charged at physiological pH (≈7.4), and so the ionization process does not influence their activity in biological media. Ionization induces very important variations in photosensitizer absorption and emission spectra. For example, absorption in the red region (band V), one of the most important characteristics of a good photosensitizer, is only important for diprotonated porphyrins and neutral chlorins. As far as fluorescence emission is concerned, neutral chlorins are almost six times more fluorescent than the corresponding neutral porphyrins (Φchlorin/Φporphyrin ≈ 6). It should be emphasized that the spectra modifications induced by pH variations can find interesting applications in the optimization of visible and fluorescence detection in high-performance liquid chromatography (HPLC) as well as in the development of direct, rapid fluorimetric analytical methods.
Surface-Enhanced Resonance Raman Scattering of Black Inkjet Dyes in Solution and in Situ Printed onto Paper
Authors: Littleford R. E. , Hughes M. P. , Dent G. , Tackley D. , Smith W. E.
Published: October 2003

Understanding the changes that occur when dyes are absorbed onto paper is crucial for the design of new inkjet dyes. This problem is particularly difficult for black dyes that have complex chromophores, and as a result, spectroscopic information on electronic and structural changes can be of importance. Surface-enhanced resonance Raman scattering (SERRS) and electronic structure calculations were used to probe in situ changes in the chromophore in black di-azo dyes printed onto paper. The data indicate that the low-energy chromophore is due mainly to the hydrazone group and the high-energy chromophore to both the azo and hydrazone groups. A comparison of SERRS from the dyes adsorbed onto silver particles in suspension and from the dyes on paper demonstrated a broadening of the chromophore into the red for both dyes and evidence of a structural change in one dye.
Two-Dimensional Correlation Spectroscopy: Effect of Reference Spectrum on Noise-Free and Noisy Spectra
Authors: Czarnecki Mirosław A.
Published: October 2003

It has been shown that for two-dimensional (2D) correlation analysis with a perturbation average, the first or the last spectrum in the data set as a reference provides identical qualitative results. On the other hand, selection of the reference spectrum significantly different from the spectra used for 2D correlation analysis may complicate interpretation of the contour plots and in consequence lead to erroneous results. The effect of noise is relatively small when 2D correlation spectra are calculated without the reference spectrum. For the other reference spectra the magnitude of the noise effect is comparable. In all cases, the asynchronous spectra are more strongly affected by the noise as compared to the synchronous spectra.