Home About us Contact
|
Home About us Contact | ||
|
|
||
Near-infrared Spectroscopy (near-infrared + spectroscopy)
Selected AbstractsNear-Infrared Spectroscopy for Plaque CharacterizationJOURNAL OF INTERVENTIONAL CARDIOLOGY, Issue 6 2008SERGIO WAXMAN M.D. A near-infrared (NIR) spectroscopy catheter-based system has been developed for intracoronary detection of lipid-rich plaques, capable of scanning an artery through blood and during cardiac motion. The lipid-rich plaque chemometric algorithm was validated in an ex vivo study using coronary artery specimens from autopsy hearts. A parallel clinical study was performed to demonstrate safety of the system in patients and the similarity of spectra acquired in vivo to data from the ex vivo study. Proof of spectral similarity between data obtained in patients and data from autopsy specimens is required to demonstrate the applicability of the algorithm to patients, in whom tissue for analysis is not available. A preliminary analysis in an unblinded cohort of patients from the clinical study reported promising results. The final results of the clinical study will be submitted for publication. The potential clinical value of this NIR spectroscopy device is discussed. [source] Optical imaging of infants' neurocognitive development: Recent advances and perspectivesDEVELOPMENTAL NEUROBIOLOGY, Issue 6 2008Yasuyo Minagawa-Kawai Abstract Near-infrared spectroscopy (NIRS) provides a unique method of monitoring infant brain function by measuring the changes in the concentrations of oxygenated and deoxygenated hemoglobin. During the past 10 years, NIRS measurement of the developing brain has rapidly expanded. In this article, a brief discussion of the general principles of NIRS, including its technical advantages and limitations, is followed by a detailed review of the role played so far by NIRS in the study of infant perception and cognition, including language, and visual and auditory functions. Results have highlighted, in particular, the developmental changes of cerebral asymmetry associated with speech acquisition. Finally, suggestions for future studies of neurocognitive development using NIRS are presented. Although NIRS studies of the infant brain have yet to fulfill their potential, a review of the work done so far indicates that NIRS is likely to provide many unique insights in the field of developmental neuroscience. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008 [source] Near-infrared spectroscopy for the determination of lipid oxidation in cereal food productsEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 12 2006Abderrahmane Aït Kaddour Abstract The present study was aimed at determining the ability of near-infrared (NIR) spectroscopy to in situ describe fat oxidation kinetics in three different cereal-based products: salted crackers (20% saturated palm oil and lauric oil, sprayed on surface); healthy crackers (10% unsaturated rapeseed oil, homogeneously distributed inside the product matrix); and moist pasteurised Asian noodles (1.5% unsaturated rapeseed oil, sprayed on surface). Products were stored under accelerated oxidation conditions at 40,°C. Lipid oxidation rates were determined from peroxide value (PV) measurements. We observed no significant changes in PV for the dry crackers (3,meq/kg after 60,days), a slight linear increase in PV for the healthy crackers (40,meq/kg after 60,days), and a rapid increase for the Asian noodles (80,meq/kg after 20,days). The NIR spectra were recorded between 1000 and 2500,nm by using a Fourier Transform NIR spectrometer, using an external probe. Measurements were done directly in situ on the product, on the ground samples, and on the extracted fat phase. The analysis of NIR spectral data by PLS statistical methods demonstrated some correlation trends (R2,=,0.575,0.897; RMSEC,=,17,55%) for the products having a significant increase in PV. It was not possible to propose predictive models to calculate the oxidation rate. [source] A near-infrared spectroscopic investigation of relative density and crushing strength in four-component compactsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 3 2009Steven M. Short Abstract Near-infrared spectroscopy (NIRS) is commonly employed for the analysis of chemical and physical attributes of intact pharmaceutical compacts. Specifically, NIRS has proven useful in the nondestructive measurement of tablet hardness or crushing strength. Near-infrared (NIR) reflectance and transmittance spectra were acquired for 174 13-mm compacts, which were produced according to a four-constituent mixture design (29 points) composed of anhydrous theophylline, lactose monohydrate, microcrystalline cellulose, and soluble starch. Six compacts were produced for each design point by compacting at multiple pressures. Physical testing and regression analyses were used to model the effect of variation in relative density (and crushing strength) on NIR spectra. Chemometric analyses demonstrated that the overall spectral variance was strongly influenced by anhydrous theophylline as a result of the experimental design and the component's spectroscopic signature. The calibration for crushing strength was more linear than the relative density model, although accuracy was poorer in comparison to the density model due to imprecision of the reference measurements. Based on the consideration of reflectance and transmittance measurements, a revised rationalization for NIR sensitivity to compact hardness is presented. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:1095,1109, 2009 [source] Near-infrared spectroscopy can predict the composition of organic matter in soil and litterJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 2 2006Thomas Terhoeven-Urselmans Abstract The usefulness and limitations of near-infrared reflectance spectroscopy (NIRS) for the assessment of several soil characteristics are still not sufficiently explored. The objective of this study was to evaluate the ability of visible and near-infrared reflectance (VIS-NIR) spectroscopy to predict the composition of organic matter in soils and litter. Reflectance spectra of the VIS-NIR region (400,2500 nm) were recorded for 56 soil and litter samples from agricultural and forest sites. Spectra were used to predict general and biological characteristics of the samples as well as the C composition which was measured by 13C-CPMAS-NMR spectroscopy. A modified partial least-square method and cross-validation were used to develop equations for the different constituents over the whole spectrum (1st to 3rd derivation). Near-infrared spectroscopy predicted well the C : N ratios, the percentages of O-alkyl C and alkyl C, the ratio of alkyl C to O-alkyl C, and the sum of phenolic oxidation products: the ratios of standard deviation of the laboratory results to standard error of cross-validation (RSC) were greater than 2, the regression coefficients (a) of a linear regression (measured against predicted values) ranged from 0.9 to 1.1, and the correlation coefficients (r) were greater than 0.9. Satisfactorily (0.8 , a , 1.2, r , 0.8, and 1.4 , RSC , 2.0) assessed were the contents of C, N, and production of DOC, the percentages of carbonyl C and aromatic C and the ratio of alkyl C to aromatic C. However, the N-mineralization rate and the microbial biomass were predicted unsatisfactorily (RSC < 1.4). The good and satisfactory predictions reported above indicate a marked usefulness of NIRS in the assessment of biological and chemical characteristics of soils and litter. [source] Near-infrared spectroscopy of the very low mass companion to the hot DA white dwarf PG 1234+482MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2007P. R. Steele ABSTRACT We present a near-infrared spectrum of the hot (Teff, 55 000 K) hydrogen atmosphere (DA) white dwarf PG 1234+482. We confirm that a very low mass companion is responsible for the previously recognized infrared photometric excess. We compare spectra of M and L dwarfs, combined with an appropriate white dwarf model, to the data to constrain the spectral type of the secondary. We find that uncertainties in the Two-Micron All-Sky Survey HK photometry of the white dwarf prevent us from distinguishing whether the secondary is stellar or substellar, and assign a spectral type of L0±1 (M9,L1).Therefore, this is the hottest and youngest (,106 yr) DA white dwarf with a possible brown dwarf companion. [source] WR 143: a Wolf,Rayet binaryMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2006Watson P. Varricatt ABSTRACT Near-infrared spectroscopy and photometry of the Wolf,Rayet star WR 143 (HD 195177) were obtained in the JHK photometric bands. High-resolution spectra observed in the J and H bands exhibit a narrow 1.083-,m He i line and the H i Pa, and Brackett series lines in emission superposed on the broad emission-line spectrum of the Wolf,Rayet star, giving strong indications of the presence of a companion. From the narrow emission lines observed, the companion is identified to be an early-type Be star. The photometric magnitudes exhibit variations in the JHK bands, which are probably due to the variability of the companion star. The flux density distribution is too steep for a Wolf,Rayet atmosphere. This is identified to be mainly due to the increasing contribution from the early-type companion star towards shorter wavelengths. [source] A noninvasive estimation of mixed venous oxygen saturation using near-infrared spectroscopy by cerebral oximetry in pediatric cardiac surgery patientsPEDIATRIC ANESTHESIA, Issue 6 2005TIA A. TORTORIELLO MD FAAP Summary Background :,Near-infrared spectroscopy (NIRS) is a noninvasive optical monitor of regional cerebral oxygen saturation (rSO2). The aim of this study was to validate the use of NIRS by cerebral oximetry in estimating invasively measured mixed venous oxygen saturation (SvO2) in pediatric postoperative cardiac surgery patients. Methods :,Twenty patients were enrolled following cardiac surgery with intraoperative placement of a pulmonary artery (PA) or superior vena cava (SVC) catheter. Five patients underwent complete biventricular repair , complete atrioventricular canal (n = 3) and other (n = 2). Fifteen patients with functional single ventricle underwent palliative procedures , bidirectional Glenn (n = 11) and Fontan (n = 4). Cerebral rSO2 was monitored via NIRS (INVOS 5100) during cardiac surgery and 6 h postoperatively. SvO2 was measured from blood samples obtained via an indwelling PA or SVC catheter and simultaneously correlated with rSO2 by NIRS at five time periods: in the operating room after weaning from cardiopulmonary bypass, after sternal closure, and in the CICU at 2, 4, and 6 h after admission. Results :,Each patient had five measurements (total = 100 comparisons). SvO2 obtained via an indwelling PA or SVC catheter for all patients correlated with rSO2 obtained via NIRS: Pearson's correlation coefficient of 0.67 (P < 0.0001) and linear regression of r2 = 0.45 (P < 0.0001). Separate linear regression of the complete biventricular repairs demonstrated an r = 0.71, r2 = 0.50 (P < 0.0001). Bland,Altman analysis showed a bias of +3.3% with a precision of 16.6% for rSO2 as a predictor of SvO2 for all patients. Cerebral rSO2 was a more accurate predictor of SvO2 in the biventricular repair patients (bias ,0.3, precision 11.8%), compared with the bidirectional Glenn and Fontan patients. Conclusions :,Regional cerebral oximetry via NIRS correlates with SvO2 obtained via invasive monitoring. However, the wide limits of agreement suggest that it may not be possible to predict absolute values of SvO2 for any given patient based solely on the noninvasive measurement of rSO2. Near-infrared spectroscopy, using the INVOS 5100 cerebral oximeter, could potentially be used to indicate trends in SVO2, but more studies needs to be performed under varying clinical conditions. [source] Low-temperature photopolymerization and post-cure characteristics of acrylatesPOLYMER INTERNATIONAL, Issue 6 2007Xia Gao Abstract Near-infrared spectroscopy was used to investigate the post-cure characteristics of acrylates polymerized from , 75 °C up to room temperature. The results obtained showed that the double bond conversion increased with increasing initiator concentration. Post-cure was much more striking for samples cured at lower temperatures. The chemical structure of monomer and photoinitiator had a great effect on the post-cure process. The greater the functionality, the lower the final double bond conversion and the more distinct the post-cure effect. Copyright © 2006 Society of Chemical Industry Society of Chemical Industry [source] Understanding the kinetics and network formation of dimethacrylate dental resinsPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 6 2001Lale G. Lovell Abstract Dimethacrylate monomers are commonly used as the organic phase of dental restorative materials but many questions remain about the underlying kinetics and network formation in these highly crosslinked photopolymer systems. Several novel experimental and modeling techniques that have been developed for other multifunctional (meth)acrylates were utilized to gain further insight into these resin systems. Specifically, this work investigates the copolymerization behavior ofbis-GMA (2,2-bis[p-(2-hydroxy-3-methacryloxyprop-1-oxy)-phenyl]propane) and TEGDMA (triethylene glycol dimethacrylate), two monomers typically used for dental resin formulations. Near-infrared spectroscopy, electron paramagnetic resonance spectroscopy, as well as dynamic mechanical and dielectric analysis were used to characterize the kinetics, radical populations, and structural properties of this copolymer system. In addition, a kinetic model is described that provides valuable information about the network evolution during the formation of this crosslinked polymer. The results of these numerous studies illustrate that all of the aforementioned techniques can be readily applied to dental resin systems and consequently can be used to obtain a wealth of information about these systems. The application of these techniques provides insight into the complex polymerization kinetics and corresponding network formation, and as a result, a more complete understanding of the anomolous behaviors exhibited by these systems, such as diffusion controlled kinetics and conversion dependent network formation, is attained. Copyright © 2001 John Wiley & Sons, Ltd. [source] Near-infrared spectroscopy grades the severity of intermittent claudication in diabetics more accurately than ankle pressure measurement,BRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 4 2000Dr T. Komiyama Background: The aim of this study was to evaluate near-infrared spectroscopy (NIRS), combined with a treadmill-walking test, as a method of assessment of intermittent claudication (IC) in diabetic patients. Methods: Some 208 symptomatic legs in 153 consecutive patients who complained of calf IC due to atherosclerotic disease were studied with NIRS and resting ankle: brachial pressure index (ABPI). Results: There was good reproducibility of NIRS measurements. Three distinct types of IC were detected by NIRS. ABPI was significantly different between these three types in non-diabetic patients, but could not grade the severity of IC in diabetic patients. Recovery time (RT) of muscle oxygenation differentiated more accurately between severe and moderate claudication than ABPI in diabetics, although RT and ABPI had similar accuracy in non-diabetics. There was a significant correlation between RT and ABPI in non-diabetic patients and patients who had been diabetic for less than 10 years, while there was no correlation in patients who had had diabetes for over 10 years. Conclusion: Measurement of muscle oxygenation during exercise by NIRS graded the severity of IC in diabetic patients more accurately than resting ABPI. © 2000 British Journal of Surgery Society Ltd [source] Cerebral oxygenation decreases but does not impair performance during self-paced, strenuous exerciseACTA PHYSIOLOGICA, Issue 4 2010F. Billaut Abstract Aim:, The reduction in cerebral oxygenation (Cox) is associated with the cessation of exercise during constant work rate and incremental tests to exhaustion. Yet in exercises of this nature, ecological validity is limited due to work rate being either fully or partly dictated by the protocol, and it is unknown whether cerebral deoxygenation also occurs during self-paced exercise. Here, we investigated the cerebral haemodynamics during a 5-km running time trial in trained runners. Methods:, Rating of perceived exertion (RPE) and surface electromyogram (EMG) of lower limb muscles were recorded every 0.5 km. Changes in Cox (prefrontal lobe) were monitored via near-infrared spectroscopy through concentration changes in oxy- and deoxyhaemoglobin (,[O2Hb], ,[HHb]). Changes in total Hb were calculated (,[THb] = ,[O2Hb] + ,[HHb]) and used as an index of change in regional blood volume. Results:, During the trial, RPE increased from 6.6 ± 0.6 to 19.1 ± 0.7 indicating maximal exertion. Cox rose from baseline to 2.5 km (,,[O2Hb], ,,[HHb], ,,[THb]), remained constant between 2.5 and 4.5 km, and fell from 4.5 to 5 km (,,[O2Hb], ,,[HHb], ,,[THb]). Interestingly, the drop in Cox at the end of the trial coincided with a final end spurt in treadmill speed and concomitant increase in skeletal muscle recruitment (as revealed by higher lower limb EMG). Conclusion:, Results confirm the large tolerance for change in Cox during exercise at sea level, yet further indicate that, in conditions of self-selected work rate, cerebral deoxygenation remains within a range that does not hinder strenuous exercise performance. [source] The effect of hypoxia on pulmonary O2 uptake, leg blood flow and muscle deoxygenation during single-leg knee-extension exerciseEXPERIMENTAL PHYSIOLOGY, Issue 3 2004Darren S. DeLorey The effect of hypoxic breathing on pulmonary O2 uptake (VO2p), leg blood flow (LBF) and O2 delivery and deoxygenation of the vastus lateralis muscle was examined during constant-load single-leg knee-extension exercise. Seven subjects (24 ± 4 years; mean ±s.d.) performed two transitions from unloaded to moderate-intensity exercise (21 W) under normoxic and hypoxic (PETO2= 60 mmHg) conditions. Breath-by-breath VO2p and beat-by-beat femoral artery mean blood velocity (MBV) were measured by mass spectrometer and volume turbine and Doppler ultrasound (VingMed, CFM 750), respectively. Deoxy-(HHb), oxy-, and total haemoglobin/myoglobin were measured continuously by near-infrared spectroscopy (NIRS; Hamamatsu NIRO-300). VO2p data were filtered and averaged to 5 s bins at 20, 40, 60, 120, 180 and 300 s. MBV data were filtered and averaged to 2 s bins (1 contraction cycle). LBF was calculated for each contraction cycle and averaged to 5 s bins at 20, 40, 60, 120, 180 and 300 s. VO2p was significantly lower in hypoxia throughout the period of 20, 40, 60 and 120 s of the exercise on-transient. LBF (l min,1) was approximately 35% higher (P > 0.05) in hypoxia during the on-transient and steady-state of KE exercise, resulting in a similar leg O2 delivery in hypoxia and normoxia. Local muscle deoxygenation (HHb) was similar in hypoxia and normoxia. These results suggest that factors other than O2 delivery, possibly the diffusion of O2, were responsible for the lower O2 uptake during the exercise on-transient in hypoxia. [source] TATA Box-Binding Protein gene is associated with risk for schizophrenia, age at onset and prefrontal functionGENES, BRAIN AND BEHAVIOR, Issue 4 2009K. Ohi Schizophrenia is a common polygenic disease in distinct populations, while spinocerebellar ataxia type 17 (SCA17) is a rare autosomal dominant neurodegenerative disorder. Both diseases involve psychotic symptoms. SCA17 is caused by an expanded polyglutamine tract in the TATA box-binding protein (TBP) gene. In the present study, we investigated the association between schizophrenia and CAG repeat length in common TBP alleles with fewer than 42 CAG repeats in a Japanese population (326 patients with schizophrenia and 116 healthy controls). We found that higher frequency of alleles with greater than 35 CAG repeats in patients with schizophrenia compared with that in controls (p = 0.042). We also examined the correlation between CAG repeats length and age at onset of schizophrenia. We observed a negative correlation between the number of CAG repeats in the chromosome with longer CAG repeats out of two chromosomes and age at onset of schizophrenia (p = 0.020). We further provided evidence that TBP genotypes with greater than 35 CAG repeats, which were enriched in patients with schizophrenia, were significantly associated with hypoactivation of the prefrontal cortex measured by near-infrared spectroscopy during the tower of Hanoi, a task of executive function (right PFC; p = 0.015, left PFC; p = 0.010). These findings suggest possible associations of the genetic variations of the TBP gene with risk for schizophrenia, age at onset and prefrontal function. [source] Enhancement of activity of the primary visual cortex during processing of emotional stimuli as measured with event-related functional near-infrared spectroscopy and event-related potentialsHUMAN BRAIN MAPPING, Issue 1 2008Martin J. Herrmann Abstract In this study we investigated whether event-related near-infrared spectroscopy (NIRS) is suitable to measure changes in brain activation of the occipital cortex modulated by the emotional content of the visual stimuli. As we found in a previous pilot study that only positive but not negative stimuli differ from neutral stimuli (with respect to oxygenated haemoglobin), we now measured the event-related EEG potentials and NIRS simultaneously during the same session. Thereby, we could evaluate whether the subjects (n = 16) processed the positive as well as the negative emotional stimuli in a similar way. During the task, the subjects passively viewed positive, negative, and neutral emotional pictures (40 presentations were shown in each category, and pictures were taken from the International Affective Picture System, IAPS). The stimuli were presented for 3 s in a randomized order (with a mean of 3 s interstimulus interval). During the task, we measured the event-related EEG potentials over the electrode positions O1, Oz, O2, and Pz and the changes of oxygenated and deoxygenated haemoglobin by multichannel NIRS over the occipital cortex. The EEG results clearly show an increased early posterior negativity over the occipital cortex for both positive as well as negative stimuli compared to neutral. The results for the NIRS measurement were less clear. Although positive as well as negative stimuli lead to significantly higher decrease in deoxygenated haemoglobin than neutral stimuli, this was not found for the oxygenated haemoglobin. Hum Brain Mapp 29:28,35, 2008. © 2007 Wiley-Liss, Inc. [source] Simultaneous measurements of cerebral oxygenation changes during brain activation by near-infrared spectroscopy and functional magnetic resonance imaging in healthy young and elderly subjectsHUMAN BRAIN MAPPING, Issue 1 2002D. Jannet Mehagnoul-Schipper Abstract Near infrared spectroscopy (NIRS) and functional magnetic resonance imaging (fMRI) both allow non-invasive monitoring of cerebral cortical oxygenation responses to various stimuli. To compare these methods in elderly subjects and to determine the effect of age on cortical oxygenation responses, we determined motor-task-related changes in deoxyhemoglobin concentration ([HHb]) over the left motor cortex in six healthy young subjects (age 35 ± 9 years, mean ± SD) and five healthy elderly subjects (age 73 ± 3 years) by NIRS and blood-oxygen-level-dependent (BOLD) fMRI simultaneously. The motor-task consisted of seven cycles of 20-sec periods of contralateral finger-tapping at a rate as fast as possible alternated with 40-sec periods of rest. Time-locked averages over the seven cycles were used for further analysis. Task-related decreases in [HHb] over the motor cortex were measured by NIRS, with maximum changes of ,0.83 ± 0.38 ,mol/L (P < 0.01) for the young and ,0.32 ± 0.17 ,mol/L (P < 0.05) for the elderly subjects. The BOLD-fMRI signal increased over the cortex volume under investigation with NIRS, with maximum changes of 2.11 ± 0.72% (P < 0.01) for the young and 1.75 ± 0.71% (P < 0.01) for the elderly subjects. NIRS and BOLD-fMRI measurements showed good correlation in the young (r = ,0.70, r2 = 0.48, P < 0.001) and elderly subjects (r = ,0.82, r2 = 0.67, P < 0.001). Additionally, NIRS measurements demonstrated age-dependent decreases in task-related cerebral oxygenation responses (P < 0.05), whereas fMRI measurements demonstrated smaller areas of cortical activation in the elderly subjects (P < 0.05). These findings demonstrate that NIRS and fMRI similarly assess cortical oxygenation changes in young subjects and also in elderly subjects. In addition, cortical oxygenation responses to brain activation alter with aging. Hum. Brain Mapping 16:14,23, 2002. © 2002 Wiley-Liss, Inc. [source] Noncontact measurement of deep tissue absorption coefficient using Spatially Resolved Near-Infrared SpectroscopyIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 4 2007Masatsugu Niwayama Member Abstract We examined the influence of probe-tissue distance on the relationship between the deep tissue absorption coefficient and the spatial profile of light intensity by Monte Carlo simulation and in vivo experiments, using noncontact spatially resolved near-infrared spectroscopy (SRS). These results suggest that noncontact SRS can be reliably used for noncontact measurement of the absorption coefficient and oxygen saturation of deep tissues. © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] Bayesian regularization: application to calibration in NIR spectroscopyJOURNAL OF CHEMOMETRICS, Issue 11 2009C. E. Alciaturi Abstract The use of a Bayesian regularization algorithm is proposed for calibration in near-infrared spectroscopy (NIR) with linear models. The algorithm used in this work is based upon the concepts developed by MacKay for inference and model comparison in artificial neural networks. It is demonstrated that this algorithm is fast, easy to use, and shows good generalization properties without previous dimensionality reduction. Examples are shown for NIR spectroscopy calibration and synthetic data. Copyright © 2009 John Wiley & Sons, Ltd. [source] A new family of genetic algorithms for wavelength interval selection in multivariate analytical spectroscopyJOURNAL OF CHEMOMETRICS, Issue 6 2003Héctor C. Goicoechea Abstract A new procedure is presented for wavelength interval selection with a genetic algorithm in order to improve the predictive ability of partial least squares multivariate calibration. It involves separately labelling each of the selected sensor ranges with an appropriate inclusion ranking. The new approach intends to alleviate overfitting without the need of preparing an independent monitoring sample set. A theoretical example is worked out in order to compare the performance of the new approach with previous implementations of genetic algorithms. Two experimental data sets are also studied: target parameters are the concentration of glucuronic acid in complex mixtures studied by Fourier transform mid-infrared spectroscopy and the octane number in gasolines monitored by near-infrared spectroscopy. Copyright © 2003 John Wiley & Sons, Ltd. [source] Monitoring of a batch organic synthesis by near-infrared spectroscopy: modeling and interpretation of three-way dataJOURNAL OF CHEMOMETRICS, Issue 7 2002Paul Geladi Abstract Three-way data of the type batch,×,time,×,NIR wavelength were obtained by NIR spectroscopic multivariate monitoring of an organic synthesis as a batch process. The model synthesis, an ester synthesis, was carried out as an experimental design. Unexpected technical problems caused a blocking effect that forced a modification of the design. After preprocessing of a reduced three-way array, the spectral data in the three-way array were subjected to parallel factor analysis (PARAFAC). The loadings from this analysis could be interpreted and explained as a function of the synthesis studied. For the spectral interpretation, spectra of pure chemicals were needed. The paper is an illustration of what can be done with three-way modeling in order to increase the understanding of a reaction, and it attempts to show how the results can be interpreted and presented. The data sets are available from the authors. Copyright © 2002 John Wiley & Sons, Ltd. [source] The effect of pneumoperitoneum in the steep Trendelenburg position on cerebral oxygenationACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 7 2009E. Y. PARK Background: daVinci® robot-assisted laparoscopic radical prostatectomy (RALP) requires pneumoperitoneum in the steep Trendelenburg position, which results in increased intracranial pressure and cerebral blood flow. The aim of this study was to evaluate the effect of pneumoperitoneum in a 30° Trendelenburg position on cerebral oxygenation using regional cerebral oxygen saturation (rSO2). Methods: Thirty-two male patients of ASA I and II physical status without previous episodes of cerebral ischemia or hemorrhage undergoing daVinci® RALP were enrolled. The rSO2 was continuously monitored with near-infrared spectroscopy (INVOS® 5100Ô) during the study period. Measurements were obtained immediately after anesthesia induction (T0; baseline), 5 min after a 30° Trendelenburg position (T1), 5 min after 15 mmHg pneumoperitoneum in a supine position (T2), 30, 60 and 120 min after the pneumoperitoneum in a Trendelenburg position (T3, T4 and T5, respectively) and after desufflation in a supine position (T6). Results: The change in the left and right rSO2 was statistically significant (Left P=0.004 and Right P=0.023). Both the right and the left rSO2 increased significantly during pneumoperitoneum in a Trendelenburg position (from T3 to T5) and at T6 compared with the baseline value at T0. The partial pressure of carbon dioxide (PaCO2) was increased significantly at T2, T3, T5 and T6 compared with the baseline value at T0. Conclusions: During daVinci® RALP, cerebral oxygenation, as assessed by rSO2, increased slightly, which suggests that the procedure did not induce cerebral ischemia. The PaCO2 should be maintained within the normal limit during pneumoperitoneum in a Trendelenburg position in patients undergoing daVinci® RALP because the rSO2 increased in conjunctions with the increase in PaCO2. [source] Determination of fluidized bed granulation end point using near-infrared spectroscopy and phenomenological analysisJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 3 2005W. Paul Findlay Abstract Simultaneous real-time monitoring of particle size and moisture content by near-infrared spectroscopy through a window into the bed of a fluidized bed granulator is used to determine the granulation end point. The moisture content and particle size determined by the near-infrared monitor correlates well with off-line moisture content and particle size measurements. The measured particle size is modeled using a population balance approach, and the moisture content is shown to follow accepted models during drying. Given a known formulation, with predefined parameters for peak moisture content, final moisture content, and final granule size, the near-infrared monitoring system can be used to control a fluidized bed granulation by determining when binder addition should be stopped and when drying of the granules is complete. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:604,612, 2005 [source] Prediction of model pools for a long-term experiment using near-infrared spectroscopyJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 1 2010Kerstin Michel Abstract Fourty-one soil samples from the "Eternal Rye" long-term experiment in Halle, Germany, were used to test the usefulness of near-infrared spectroscopy (NIRS) to differentiate between C derived from C3 and C4 plants by using the isotopic signature (,13C) and to predict the pools considered in the Rothamsted Carbon (RothC) model, i.e., decomposable plant material, resistant plant material, microbial biomass, humified organic matter, and inert organic matter. All samples were scanned in the visible-light and near-infrared region (400,2500 nm). Cross-validation equations were developed using the whole spectrum (first to third derivative) and a modified partial least-square regression method. ,13C values and all pools of the RothC model were successfully predicted by NIRS as reflected by RSC values (ratio between standard deviation of the laboratory results and standard error of cross-validation) ranging from 3.2 to 3.4. Correlations analysis indicated that organic C can be excluded as basis for the successful predictions by NIRS in most cases, i.e., 11 out of 16. [source] Influence of substituents on the kinetics of epoxy/aromatic diamine resin systemsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 13 2004Heping Liu Abstract Eleven different epoxy/diamine systems, including tetraglycidyl-4,4,-diaminodiphenylmethane (TGDDM), triglycidyl p -aminophenol (TGAP), and diglycidyl ether of bisphenol A (DGEBA) with 4,4,-diaminodiphenylsulfone (DDS), diethyltoluenediamine (DETDA), dimethylthiotoluenediamine (DMTDA), and meta -phenylenediamine (m -PDA), were studied with near-infrared spectroscopy at different temperatures. The reactivities of the epoxies were determined and found to be in the following order when reacted with the same amine: DGEBA > TGAP > TGDDM. When the primary amine was reacted with the same epoxy, the order was DETDA > DDS > DMTDA; for the secondary amine, the order was DETDA > DMTDA > DDS. The relative reaction rates of the secondary amine to the primary amine were compared and discussed in terms of the structural differences and the corresponding substitution effect. It was concluded that the increase in the secondary amine reactivity of DETDA and DMTDA was caused by the deconjugation of the benzene-ring , electrons from the lone pair on the N atom. The overall order of the secondary amine relative reactivity was DMTDA > DETDA > DDS for the same epoxy and TGDDM > TGAP > DGEBA for the same amine. The m -PDA systems had no significant positive or negative substitution effects. Molecular orbital calculations were performed, and the results showed the most significant deconjugation effect in the secondary amine of DETDA. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3143,3156, 2004 [source] High-Temperature Propagation and Termination Kinetics of Styrene to High Conversion Investigated by Electron Paramagnetic Resonance SpectroscopyMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 6 2004Per B. Zetterlund Abstract Summary: The free radical bulk polymerization of styrene at 120,°C has been investigated over almost the entire conversion range using electron paramagnetic resonance spectroscopy, Fourier-transform near-infrared spectroscopy and gel permeation chromatography. The free radical concentration went through a sharp maximum that coincided with the peak in the rate of polymerization during the gel effect, and shifted to higher conversion with increasing initiator concentration. The termination rate coefficient (kt), decoupled from the initiator efficiency (f) by use of the instantaneous degree of polymerization, remained close to constant up to as high as approximately 80% conversion, at which a dramatic decrease occurred. Both the propagation rate coefficient (kp) and f fell orders of magnitude near 80% conversion in spite of the temperature being above the glass transition temperature of the system. The value of kp increased with the initiator concentration at a given conversion in the highest (diffusion-controlled) conversion range. Termination rate coefficient (kt) versus conversion for bulk free radical polymerization of St initiated by TBP at 120,°C. [TBP],=,0.15 (,), 0.10 (,) and 0.05 M (). [source] The effect of bloodless pump prime on cerebral oxygenation in paediatric patientsACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 5 2004S. H. Han Background:, In paediatric patients, crystalloid prime for cardiopulmonary bypass (CPB) causes further haemodilution in comparison with blood-containing prime. Thus it may affect the cerebral oxygen supply/demand balance. The purpose of the study was to compare the effect of bloodless pump prime with that of blood-containing prime on cerebral oxygenation in children. Methods:, Thirty-six paediatric patients scheduled for elective repair of atrial or ventricular septal defect were enrolled. In Group C (n = 18), the CPB circuit was primed only with crystalloid. In Group B (n = 18), red blood cells were added to achieve a haematocrit (Hct) of 20% during CPB. The regional cerebral oxygen saturation (rSO2) value measured by near-infrared spectroscopy was compared between the two groups. Results:, In both groups, rSO2 decreased below baseline at the start of CPB and during rewarming (P < 0.001, for both groups during each period). At the start of CPB, haemodilution was greater in Group C than in Group B (Hct 16.1 ± 0.7% vs. 20.7 ± 0.5%; P < 0.01), and there was a greater reduction in rSO2 in Group C (49.0 ± 5.4% vs. 59.2 ± 7.0%; P < 0.01). During rewarming, rSO2 was significantly lower in Group C than in Group B (57.8 ± 5.3% vs. 62.8 ± 6.2%; P < 0.01). Conclusions:, In paediatric patients, the haemodilution associated with crystalloid priming causes a greater reduction in rSO2 than with blood-containing prime at the starting period of CPB and the rewarming period. [source] Impaired oxygen extraction in metabolic myopathies: Detection and quantification by near-infrared spectroscopyMUSCLE AND NERVE, Issue 4 2007Bruno Grassi MD Abstract Patients with mitochondrial myopathies (MM) or myophosphorylase deficiency (McArdle's disease, McA) show impaired capacity for O2 extraction, low maximal aerobic power, and reduced exercise tolerance. Non-invasive tools are needed to quantify the metabolic impairment. Six patients with MM, 6 with McA, 25 with symptoms of metabolic myopathy but negative biopsy (patient-controls, P-CTRL) and 20 controls (CTRL) underwent an incremental cycloergometric test. Pulmonary O2 uptake (V,O2) and vastus lateralis oxygenation indices (by near-infrared spectroscopy, NIRS) were determined. Concentration changes of deoxygenated hemoglobin and myoglobin (,[deoxy(Hb + Mb)]) were considered an index of O2 extraction. ,[deoxy(Hb + Mb)] peak (percent limb ischemia) was lower in MM (25.3 ± 12.0%) and McA (18.7 ± 7.3) than in P-CTRL (62.4 ± 3.9) and CTRL (71.3 ± 3.9) subjects. V,O2 peak and ,[deoxy(Hb + Mb)] peak were linearly related (r2 = 0.83). In these patients, NIRS is a tool to detect and quantify non-invasively the metabolic impairment, which may be useful in the follow-up of patients and in the assessment of therapies and interventions. Muscle Nerve, 2006 [source] Surgical closure of patent ductus arteriosus reduces the cerebral tissue oxygenation index in preterm infants: a near-infrared spectroscopy and Doppler studyPEDIATRICS INTERNATIONAL, Issue 3 2006PATRIZIA ZARAMELLA Abstract Background: The aim of this study was to investigate the effects of patent ductus arteriosus (PDA) ligature on cerebral oxygen saturation, cerebral blood volume (CBV) and cerebral blood flow velocity by means of near-infrared spectroscopy (NIRS) and transcranial Doppler simultaneous examinations. Methods: This is an observational study considering 16 babies of gestational age 24,34 weeks diagnosed with PDA who underwent surgical ligation. The cerebral oxygen saturation, CBV and blood gases values were obtained 35 min before ligation, so also around the 14th and 27th min after the clip's insertion. Results: Cerebral oxygen saturation, measured as tissue oxygenation index (TOI), decreased significantly after PDA ligation from a basal value of 61.1 (3.8) before surgery to 56.6 (3.3) and 55.8 (2.6)%, for the 14th and 27th min, respectively (P < 0.04). CBV before and after clipping was unvaried. A negative correlation was found between ,pH and ,CBV after ligation (R = 0.52, P = 0.03), whilst a positive correlation was found between ,CBV and ,PaCO2 (R = 0.62, P = 0.009). pH increased at the 27th min post-ligation. Conclusions: NIRS is a tool for obtaining information on cerebral oxygen saturation and CBV changes during surgical PDA ligation at the bedside. A fall in TOI suggests an increased oxygen extraction during PDA surgery. The lack of increase in ,CBV or in diastolic flow velocity show that the PDA before the clipping did not limit cerebral blood flow, the drop in TOI suggests increased oxygen consumption over the clip and the need for accurate monitoring of oxygen utilization after the surgical treatment. [source] Activation of the prefrontal cortex to trauma-related stimuli measured by near-infrared spectroscopy in posttraumatic stress disorder due to terrorismPSYCHOPHYSIOLOGY, Issue 4 2003Koji Matsuo Abstract To develop a noninvasive method for psychophysiological assessment of posttraumatic stress disorder (PTSD), 34 victims of the Tokyo Subway Sarin Attack in 1995 including 8 diagnosed as PTSD and 12 controls were examined by a multichannel near-infrared spectroscopy (NIRS) system. Hemodynamic response in the prefrontal cortex was monitored during the presentation of trauma-related and control stimuli by video images. Skin conductance response (SCR) was also examined. Oxygenated hemoglobin significantly increased during the trauma-related image in the victims with or without PTSD. Deoxygenated hemoglobin significantly decreased only in victims with PTSD. No significant alteration was found in controls. Significantly enhanced SCR was also observed in the victims with PTSD during trauma-related stimuli. The findings suggest that measurement of cerebral hemodynamic response by NIRS is useful for psychophysiological assessment of PTSD. [source] Changes in cerebral oxygenation in children undergoing surgical repair of ventricular septal defectsANAESTHESIA, Issue 1 2003Y. Morimoto Summary There have been few published studies on changes in cerebral oxygenation during paediatric cardiac surgery as measured by conventional near-infrared spectroscopy. We studied changes in cerebral oxygenation in 16 children undergoing surgical repair of ventricular septal defects. Fifteen of the patients showed similar patterns of changes: brain tissue concentrations of oxyhaemoglobin decreased significantly during cardiopulmonary bypass, whereas there was no significant change in brain tissue concentrations of deoxyhaemoglobin. In the remaining patient, who suffered decreased blood flow to the lower body during surgery, the pattern of changes was different to that of the other subjects. This patient suffered postoperative respiratory and renal failure. This study suggests that conventional near-infrared spectroscopy may be useful for clinical monitoring during ventricular septal defect repair. [source] | |||||||||||||||||||||||||||||||