Infrared Spectroscopy Methods Research Articles

Spectral Analysis of Event-Related Hemodynamic Responses in Functional Near Infrared Spectroscopy

The goal of this paper is to design experiments that confirm the evidence of cognitive responses in functional near infrared spectroscopy and to establish relevant spectral subbands. Hemodynamic responses of brain during single-event trials in an odd-ball experiment are measured by functional near infrared spectroscopy method. The frequency axis is partitioned into subbands by clustering the time-frequency power spectrum profiles of the brain responses. The predominant subbands are observed to confine the 0-30 mHz, 30-60 mHz, and 60-330 mHz ranges. We identify the group of subbands that shows strong evidence of protocol-induced periodicity as well as the bands where good correlation with an assumed hemodynamic response models is found.

Mechanism of formation of cobalt nanoparticles in a nanoreactor based on supramolecular system [LiAl2(OH)6]2[Coedta]·nH2O

DTA (differential thermal analysis), XPA (XRD phase analysis), FMR (ferromagnetic resonance), and IR (infrared spectroscopy) methods were used to study the formation of nanosized particles of cobalt in a nanoreactor based on supramolecular system [LiAl2(OH)6]2[Coedta]·nH2O. It was shown that under thermal decomposition of this phase at temperatures above 325°C, an amorphous phase containing cobalt(II) cations in the oxygen (nitrogen) surrounding, carbonized product (coke) as well as XRD-amorphous lithium aluminate are formed. Further interaction of the amorphous cobalt-containing phase with coke leads to the formation of nanosized ferromagnetic particles of cobalt covered with a layer of coke and lithium aluminate.

Application of a Portable near Infrared Spectrometer for the Manufacturing of Noodle Products

We applied the rapid, non-destructive and convenient near infrared (NIR) spectroscopy method, using a portable NIR spectrometer, to the manufacturing process of noodle products (Inaniwa Udon). Characterisation of wheat flours, which are a primary ingredient of noodle products, was identified easily by the pricipal component (PC) score plots based on the standardised NIR spectra. We assessed these results not only from a practical standpoint, but also for the chemical interpretation of NIR spectra. Without any sample preparation, NIR spectra revealed moisture content in the products. Further investigation revealed that moisture content is proportional to viable bacterial counts in the products, so determining moisture content in products by the rapid, non-destructive and convenient method of using a portable NIR spectrometer, as used in this work, is extremely useful in the Inaniwa Udon quality control process.

Metastability in Undoped Microcrystalline Silicon Thin Films Deposited by HWCVD

ABSTRACTFilms deposited by the Hot Wire CVD method were studied by means of dark conductivity, FTIR, Hydrogen Evolution, SEM and AFM surface characterization. Three types of metastability were observed: a) long term irreversible degradation due to oxidization processes on the film surface, b) reversible degradation determined by uncontrolled water adsorption, c) fast field switching effect in the film bulk.Oxygen and hydrogen content and its bonding configurations have been analyzed by hydrogen evolution and infrared spectroscopy methods on the films deposited on glass substrates and silicon wafers subsequently. It has been found that metastable processes close to the film surface are stronger than in the bulk. The switching effect is the fast increase of charge carrier density observed on bottom chromium contacts under a condition of air admittance. We propose this effect is associated with morphology changes during film growth and electrical field induced by adsorbed atmospheric components on the film surface.

Infrared spectrometry of Venus: IR Fourier spectrometer on Venera 15 as a precursor of PFS for Venus express

Thermal infrared spectrometry in the range 6–40 μm with spectral resolution of 4.5–6.5 cm −1 was realized onboard of Venera 15 for the middle atmosphere of Venus investigations. The 3-D temperature and zonal wind fields ( h, ϕ, LT) in the range 55–100 km and the 3-D aerosol field ( h, ϕ, LT) in the range 55–70 km were retrieved and analyzed. The solar related waves at isobaric levels, generated by the absorbed solar energy, were investigated. In the thermal IR spectral range the, ν 1, ν 2 and ν 3 SO 2 and the H 2O rotational (40 μm) and vibro-rotational (6.3 μm) absorption bands are observed and used for minor compounds retrieval. An advantage of the thermal infrared spectrometry method is that both the temperature and aerosol profiles, which need for retrieval of the vertical profiles of minor compounds, are evaluated from the same spectrum. The Fourier spectrometer on Venera-15 may be considered as a precursor of the Planetary Fourier Spectrometer (PI Prof. V. Formisano), which is included in the payload of the planned Venus Express mission. It has a spectral range 0.9–45 μm, separated into two channels: a short wavelength channel (SWC) in the range 0.9–5 μm and a long wavelength channel (LWC) from 6 to 45 μm, and spectral resolution of 1–2 cm −1. In the history of planetary Fourier spectrometry the PFS is a unique instrument, which possesses a short wavelength channel. A functioning of this instrument on the polar orbit with a good spatial and local time coverage will advance our knowledge in the fundamental problems of the Venus atmosphere.

Latex quantification in homogenate and purified latex samples from various plant species using near infrared reflectance spectroscopy

Parthenium argentatum (guayule) is under commercial development as a source of hypoallergenic latex, which is suitable for the manufacture of latex medical devices safe for use by people suffering from Type I latex protein allergy. Improving agronomic practices, post-harvest shrub handling, and optimizing latex extraction and purification protocols during bioprocessing are hampered by the relatively cumbersome latex quantification methods currently employed. Current methods require several hours before analytical results can be obtained. The object of our study was to develop and test a near infrared (NIR) spectroscopic method for rapid quantification of latex in both wet and dried P. argentatum homogenate and purified latex samples. The procedure was tested on latex samples from Ficus elastica (Indian rubber tree), Helianthus annuus (sunflower), Hevea brasiliensis (Brazilian or para rubber tree) and Taraxacum kok-saghyz (Russian dandelion). P. argentatum latex could be accurately quantified, over a wide concentration range of 0 to 25 mg/ml. The correlations between the measured rubber content and the rubber content predicted by NIR were 0.96 and 0.91 for dry and wet samples, respectively. The presence of homogenate components unrelated to the latex fraction did not perturb the correlations obtained. Similar predictive models could be used to measure the rubber content in F. elastica, H. annuus, H. brasilensis and T. kok-saghyz.

P.4.054 Modulating effect of EGCG upon glutamate induced calcium increase in PC12 cells

Vinpocetine (Cavinton®, Gedeon Richter, Budapest) is widely used as a neuroprotective drug in the prevention and treatment of cerebrovascular diseases. Vinpocetine is a potent inhibitor of the voltage-dependent Na+ channels and a selective inhibitor of the Ca2+/caldmoduline-dependent phosphodiesterase 1. The clinical efficacy has been supported by several previous studies. Positron emission tomography (PET) is a powerful method to evaluate the fate, the site of action, the pharmacological and physiological effects of a drug in the brain and other organs. We have demonstrated in monkey that the [11C]-labelled vinpocetine rapidly enters the brain after intravenous (i.v.) injection, the maximal uptake being approximately 5% of the total injected radioactivity. The distribution pattern of vinpocetine in the brain was heterogenous, with the highest uptake in the thalamus, basal ganglia and visual cortex. These findings were confirmed in healthy humans, where the i.v. administered [11C]-labelled vinpocetine had a similar distribution pattern. The highest uptake in the brain was 3.71% of the total administered radioactivity. Quite recently, we have shown that [11C]-labelled vinpocetine administered orally to healthy human volunteers also rapidly appears in the brain and shows a similar distribution pattern, the highest uptake being 0.71% of the total administered radioactivity. In two separate sets of clinical studies where chronic ischaemic post-stroke patients were either treated with a single infusion (Study 1) or with daily vinpocetine infusion for 2 weeks (Study 2), we have shown that vinpocetine increases the regional cerebral glucose uptake and to a certain extent glucose metabolism in the so-called peri-stroke region as well as in the relatively intact brain tissue. The 2-week-long treatment also increased the regional cerebral blood flow (CBF) especially in the thalamus, basal ganglia and visual cortex of the nonsymptomatic hemisphere. We have demonstrated the cerebral perfusion-enhancing and parenchymal oxygen extraction-increasing effects of vinpocetine in subacute ischaemic stroke patients by near infrared spectroscopy (NIRS) and transcranial Doppler (TCD) methods.

Influence of polyvinylpyrrolidone on the precipitation of calcium carbonate and on the transformation of vaterite to calcite

The precipitation process of calcium carbonate (CaCO 3) in the absence and presence of poly (N-vinyl-2-pyrrolidone) (PVP) was investigated using scanning electron microscopy, powder X-ray diffraction, and Fourier transform infrared spectroscopy methods at room temperature. The results indicate that PVP does not affect the polymorphy, but has influence on their morphology and size of CaCO 3 crystals. With the addition of PVP, the amorphous CaCO 3 could aggregate into bigger amorphous spherulites before transforming to crystalline state. Also, the transformation from the thermodynamically unstable vaterite to the stable calcite was investigated in the presence of PVP. As a particle-stabilizing agent, PVP molecules inhibit the formation of vaterite, however, promote the formation of calcite as well as the rate of the solvent-mediated transformation from vaterite to calcite.

Clinical and non-clinical investigations using positron emission tomography, near infrared spectroscopy and transcranial Doppler methods on the neuroprotective drug vinpocetine: A summary of evidences

Vinpocetine (Cavinton®, Gedeon Richter, Budapest) is widely used as a neuroprotective drug in the prevention and treatment of cerebrovascular diseases. Vinpocetine is a potent inhibitor of the voltage-dependent Na + channels and a selective inhibitor of the Ca 2+/caldmoduline-dependent phosphodiesterase 1. The clinical efficacy has been supported by several previous studies. Positron emission tomography (PET) is a powerful method to evaluate the fate, the site of action, the pharmacological and physiological effects of a drug in the brain and other organs. We have demonstrated in monkey that the [ 11C]-labelled vinpocetine rapidly enters the brain after intravenous (i.v.) injection, the maximal uptake being approximately 5% of the total injected radioactivity. The distribution pattern of vinpocetine in the brain was heterogenous, with the highest uptake in the thalamus, basal ganglia and visual cortex. These findings were confirmed in healthy humans, where the i.v. administered [ 11C]-labelled vinpocetine had a similar distribution pattern. The highest uptake in the brain was 3.71% of the total administered radioactivity. Quite recently, we have shown that [ 11C]-labelled vinpocetine administered orally to healthy human volunteers also rapidly appears in the brain and shows a similar distribution pattern, the highest uptake being 0.71% of the total administered radioactivity. In two separate sets of clinical studies where chronic ischaemic post-stroke patients were either treated with a single infusion (Study 1) or with daily vinpocetine infusion for 2 weeks (Study 2), we have shown that vinpocetine increases the regional cerebral glucose uptake and to a certain extent glucose metabolism in the so-called peri-stroke region as well as in the relatively intact brain tissue. The 2-week-long treatment also increased the regional cerebral blood flow (CBF) especially in the thalamus, basal ganglia and visual cortex of the nonsymptomatic hemisphere. We have demonstrated the cerebral perfusion-enhancing and parenchymal oxygen extraction-increasing effects of vinpocetine in subacute ischaemic stroke patients by near infrared spectroscopy (NIRS) and transcranial Doppler (TCD) methods.

Blend uniformity analysis using stream sampling and near infrared spectroscopy.

A near infrared spectroscopic method was developed to determine drug content in a 20% (wt/wt) ibuprofen and spray-dried hydrous lactose blend. A blending profile was obtained after blending for 0.5, 1, 3, 5, 10, and 20 minutes. Stream sampling was used to collect about 20 blend samples at each of the blending times from a laboratory scale V-blender. The samples collected were used to develop a near infrared calibration model. The calibration model was then used to determine the drug content of unknown samples from 2 validation blends. The validation blends were not included in the calibration model; they were used to evaluate the effectiveness of the calibration model. A total of 45 samples from the 2 validation blends were predicted by the near infrared calibration model and then analyzed by a validated UV spectrophotometric method. The root mean square error of prediction for the first validation blend was 5.69 mg/g and 3.30 mg/g for the samples from the second blend. A paired t test at the 95% confidence level did not indicate any differences between the drug content predicted by the near infrared spectroscopy (NIRS) method and the validated UV method for the 2 blends. The results show that the NIRS method could be developed while the blending profile is generated and used to thoroughly characterize a new formulation during development by analyzing a large number of samples. The new formulation could be transferred to a manufacturing plant with an NIRS method to facilitate blend uniformity analysis.

Blend uniformity analysis using stream sampling and near infrared spectroscopy

A near infrared spectroscopic method was developed to determine drug content in a 20% (wt/wt) ibuprofen and spray-dried hydous lactose blend. A blending profile was obtained after blending for 0.5, 1, 3, 5, 10, and 20 minutes. Stream sampling was used to collect about 20 blend samples at each of the blending times from a laboratory scale V-blender. The samples collected were used to develop a near infrared calibration model. The calibration model was then used to determine the drug content of unknown samples from 2 validation blends. The validation blends were not included in the calibration model; they were used to evaluate the effectiveness of the calibration model. A total of 45 samples from the 2 validation blends were predicted by the near infrared calibration model and then analyzed by a validated UV spectrophotometric method. The root mean square error of prediction for the first validation blend was 5.69 mg/g and 3.30 mg/g for the samples from the second blend. A paired t test at the 95% confidence level did not indicate any differences between the drug content predicted by the near infrared spectroscopy (NIRS) method and the validated UV method for the 2 blends. The results show that the NIRS method could be developed while the blending profile is generated and used to thoroughly characterize a new formulation during development by analyzing a large number of samples. The new formulation could be transferred to a manufacturing plant with an NIRS method to facilitate blend uniformity analysis.

Use of optical methods to characterize thin silane films coated on aluminium

AbstractFor corrosion and adhesion problems, the aluminium and its alloys are usually modified by different surface treatments. Silane coupling agents that are an alternative treatment for the chromate‐containing pretreatment are being used more frequently in industry. This paper focuses on the study of a no‐rinse system using the non‐functional silane bis‐1,2‐(triethoxysilyl)ethane (BTSE). The objective of this work is to study the effect of curing BTSE films coated on aluminium substrates. Spectroscopic ellipsometry is used to determine the thickness and optical constants of the silane coatings as a function of the curing conditions. It is shown by infrared spectroscopic ellipsometry (IRSE) how the curing causes changes in the chemistry of silane films deposited on aluminium. Indeed, IRSE combines the advantages of the traditional Fourier transform infrared spectroscopy method (molecular information via knowledge of the infrared absorption bands) with those of spectroscopic ellipsometry (morphological information such as film thickness and optical information such as refractive index and extinction coefficient). Copyright © 2002 John Wiley & Sons, Ltd.

Determination of the mass fraction of methyl esters in mixed fuels

This paper presents the results of two methods employed to determine the methyl ester (ME) fraction in mixed fuels prepared from MEs of higher fatty acids and fossil Diesel fuel. The first method is based on determining the ester number of the mixed fuel. The second one utilises the measurement of the carbonyl band intensity in the mixed fuel by infrared (IR) spectroscopy. The ME fraction in the tested mixed fuels was always set to 30 wt-%. Applying the first method the ester numbers of mixed fuels were determined and the ME fraction was defined using an averaged molar mass of ME. The differences between the values of the measured and real fraction of ME varied between -0.2 and +0.8 wt-%. If the value of the average molar mass of ME was not known, the molar mass of methyl oleate was used as a reference. Thereby the differences in determining the ME fraction in mixed fuels ranged between -0.1 and +0.9 wt-%. Employing the IR spectroscopy method the differences between the measured and the real fraction of ME varied between -1.0 and +0.5 wt-%. Both methods are suitable to determine the ME fraction in mixed fuels. Cette etude presente les resultats de deux methodes de determination de la fraction d'ester methylique (EM) dans des melanges de carburants prepares a partir d'EM d'acides gras superieurs et de diesel fossile. La premiere methode calcule l'indice d'ester du melange de carburants. La seconde methode mesure l'intensite de la bande d'absorption du groupement carbonyle par spectroscopie IR.

Vinpocetine increases cerebral blood flow and oxygenation in stroke patients: a near infrared spectroscopy and transcranial Doppler study

Objective: To investigate the effect of vinpocetine on cerebral blood flow (CBF) in the compromised circulation of a stroke affected hemisphere using transcranial Doppler (TCD) and near infrared spectroscopy (NIRS) methods. Methods: 43 patients with ischemic stroke were randomized into vinpocetine (VP) and placebo group in a double blind, placebo-controlled study of the effect of a single-dose i.v. infusion of vinpocetine on cerebral blood perfusion and oxygenation. In the VP group 20 mg VP in 500 ml saline, in the placebo group 500 ml saline alone were administered. The concentrations of oxy-, reduced- and total hemoglobin were measured by NIRS frontolaterally on the side of lesion while the mean cerebral blood flow velocity (CBFV), the pulsatility index (PI) and Doppler spectral intensity (DSI) were monitored by TCD in the middle cerebral artery on the same side. Values were averaged for the first 5 min prior to the infusion and for the last 5 min of infusion and they were compared between groups. Results: The concentration of all three chromophores increased during infusion in the VP group (mean dHbT=1.03, CI 95=0.84, P=0.058; mean dHbO=0.92, CI 95=0.91, P=0.071; mean dHb=0.10, CI 95=0.21, P=0.297). The HbT and HbO showed a substantially smaller increase in the placebo group (mean dHbT=0.31, CI 95=0.74, P=0.22; mean dHbO=0.57, CI 95=0.80, P=0.094) while the Hb decreased (mean dHb=−0.26, CI 95=0.29, P=0.05). Comparing to the placebo group Hb increased significantly in the VP group ( P=0.027) while the increase of HbO and HbT did not reach the level of significance ( P=0.29 and 0.11). DSI showed a significantly larger increase in the VP than in placebo group (dDSI=25.8 CI 95=8.8 [VP]; dDSI=3.3, CI 95=3.7 [Placebo], P<0.005). The CBFV and PI did not differ significantly between groups. (dVm=5.0±2.98 cm/s [VP], dVm=4.1±2.57 cm/s [Placebo], P=0.28; dPI=0.08 [VP], dPI=0.09 [Placebo]; P=0.47). Conclusion: VP increases cerebral perfusion and parenchymal oxygen extraction as well. The increased perfusion was indicated by NIRS and by TCD measurement of DSI while conventional velocity and pulsatility measurements failed to detect theses effects. NIRS is a sensitive, feasible method of measuring changes in regional blood flow and tissue oxygenation in the superficial cortex.

Computational and Experimental Studies of the Effect of Substituents on the Singlet−Triplet Energy Gap in Phenyl(carbomethoxy)carbene

The effect of aromatic substitution on the singlet-triplet energy gap in substituted phenyl(carbomethoxy)carbene (X-Ph-C-CO(2)CH(3), PCC) has been explored by time-resolved infrared (TRIR) spectroscopy and gas-phase computational methods. The ground state of para-substituted PCC is calculated to change from the triplet state in p-NO(2)-PCC (Delta G(ST) = 6.1 kcal/mol) to the singlet state in p-NH(2)-PCC (Delta G(ST) = -2.8 kcal/mol). The absence of solvent perturbation in the TRIR spectra of p-N(CH(3))(2)-PCC (which should have electronic properties similar to p-NH(2)-PCC) and parent PCC is consistent with their ground states lying > +/-2 kcal/mol from the next available electronic state, in line with the computational results. The observation of solvent perturbation in the TRIR spectra of p-OCH(3)-PCC and p-CH(3)-PCC implies that their ground states lie < +/-1 kcal/mol from their next available electronic state. This is in agreement with our computational results, which predict a gas-phase Delta G(ST) of -0.8 and 1.6 kcal/mol for p-OCH(3)-PCC and p-CH(3)-PCC as compared to Delta G(ST) values of -3.9 and -1.3 kcal/mol from polarizable continuum model (PCM) calculations with acetonitrile as a solvent. Gas-phase computational results for the meta- and ortho-substituted PCC species are also presented, along with selected linear free energy (LFE) relationships for the para and meta species.

Prediction of the Quality of Petroleum Tars and Bitumens by Infrared Spectroscopic and X-ray Diffraction Methods

The degree of aromaticity of petroleum tars, bitumens, and their fractions is characterized by infrared spectroscopy and X-ray diffraction.

Drying Phenomenon of Moroccan Natural Phosphates Under Microwave Irradiation: Part II: Comparative studies with drying to conventional heating

ill this article, we present parallel studies on the structural, textural and morphological aspects as well as on the kinetic mechanisms of drying natural humid phosphate by conventional heating and by microwave irradiation. Experiments of drying under atmospheric pressure and under controlled temperature and incident microwave power; have been realized in the isothermal and non-isothermal regimes either in a programmable electrical oven or in a specially adapted microwave cavity. Analysis of samples was performed by various techniques: X-ray Diffraction, Scanning Electron Microscopy, Infrared Spectroscopy and BET method. The experimental results obtained under microwave irradiation are discussed and compared with these obtained by conventional heating. These comparative studies allowed to situate the action of the microwave field and compare it with the classical heating.

Characterisation of stearatestearic acid coated fillers

Selected magnesium hydroxide and calcium carbonate fillers were dry coated with stearic acid and calcium, magnesium, and zinc stearates. The course of the coating reaction was monitored using a quantitative diffuse reflectance Fourier transform infrared spectroscopy method and by thermal analysis. The coated fillers were also examined by wide angle X-ray diffraction and by X-ray photoelectron spectroscopy. These techniques were shown to produce complementary information. When the dry coating process was useded, complex reactions occurred. Stearic acid reacted to produce stearate, while the stearates melted and formed coatings, but in some cases they also appeared to form polymorphic metal stearates. Stearic acid produced the best coverage on calcium carbonate, but the poorest on magnesium hydroxide. Of the metal stearates, the best filler coverage was produced when zinc stearate was used, while calcium stearate was the least effective coating.

Quality Control During Processing of Feta Cheese—NIR Application

This work examines the possibility of using near infrared (NIR) spectroscopic method for the production process control of the traditional Greek feta cheese. A NIR apparatus (Instalab 600-Dickey–John) was employed. Moisture, fat and protein determinations were selected as calibration set for the instrument. Samples were drawn from well-defined critical points of production. In all the samples conventional chemical methods were applied for the quantitative determination of the above ingredients. Results were compared with the respective data from NIR apparatus. All data were processed by a suitable computer program so that the calibration constants could be calculated and then stored in the apparatus. Their accuracy was verified using an independent set of analyzed samples. Because the NIR apparatus used in this work was not suitable for liquid products, a novel technique was developed using “quartz fine granular washed and calcined GR” (pro analysi). This technique proved to be reliable with a significant accuracy. From this study it can be concluded that NIR technique can be applied successfully for the on-line quality control of the feta cheese production. The reliability, significant reduction of human errors, precision and quickness of NIR spectroscopy experienced during this work, support the implementation of this method.

IR spectra and their application for evaluating physical properties of fluorophosphate glasses

Infrared (IR) absorbance spectra in the range 500–4000 cm −1 of the glasses in the system Ba(PO 3) 2–MgF 2–CaF 2–AlF 3 have been studied with increasing fluoride content. Quantitative justification for assignment of some bands has been attempted. The spectra reveal that the glass structure changes with fluoride addition from metaphosphate, (PO 3 −) n to P 2(O,F) 7 and P(O,F) 4 along with the formation of Al(O,F) 6,[AlF 6] 3− and [AlF 4] −. As a result of these structural changes density ( d), refractive index n e) and IR band absorption coefficient at ∼2170 cm −1(α IR ) of the glasses vary exhibiting maxima at ∼ 36 mol% fluoride. Statistical analyses show that d and n e are correlated with α IR by linear equations. Each of these equations gives a high correlation coefficient ( r) and low residual standard deviation (RSD), and may, thus, be employed for the evaluation of physical properties of fluorophosphate glasses. Physical properties of some fluorophosphate glasses of this work and the published literature have been calculated by using these equations to test their validity. The experimental properties of the glasses present a very good fit of data within 95% confidence interval of the calculated mean values. These facts indicate the suitability of this IR spectroscopic method for the determination of physical properties of fluorophosphate glasses.