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Spectral Patterns (spectral + pattern)
Selected AbstractsSignificant differences in proton trimethyl ammonium signals between human gastrocnemius and soleus muscleJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 5 2004Jiani Hu PhD Abstract Purpose To study the apparent heterogeneous characteristics of trimethyl ammonium (TMA) in healthy human muscles at rest, and to illustrate the importance of establishing the baseline characteristics of proton metabolites in muscles with a West Nile patient. Materials and Methods Point-resolved spectroscopy (PRESS) magnetic resonance spectroscopy imaging (MRSI) with lipid suppression and optional outer-volume presaturation were used to acquire 1H spectra of human muscles at rest at 1.5 Tesla. A total of 28 subjects (27 normal volunteers and 1 patient with West Nile disease) between the ages of 22 and 76 participated in the study. Results The apparent T2 values of TMA for soleus and gastrocnemius muscles in normal volunteers are 180 ± 50 and 80 ± 20 msec, respectively. This difference has profound effects on the apparent spectral pattern of 1H metabolites. The TMA/total creatine (tCr) spectral pattern of the soleus muscle of a West Nile patient resembles that of gastrocnemius muscle of healthy volunteers. Conclusion There are significant differences in the apparent T2 values of TMA between healthy soleus and gastrocnemius muscles at rest. It is important to establish the baseline characteristics of proton metabolites before clinical or physiological studies can be performed. J. Magn. Reson. Imaging 2004;19:617,622. © 2004 Wiley-Liss, Inc. [source] Evaluation of the reduction of imidazophenazine dye derivatives under fast-atom-bombardment mass-spectrometric conditions,JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 1 2006Marina V. Kosevich Abstract Satellite [M + 2]+, and [M + 3]+ peaks accompanying the common peak of the protonated molecule [M + H]+ that are known to indicate the occurrence of a reduction process were observed in the fast atom bombardment (FAB) mass spectra of imidazophenazine dye derivatives in glycerol matrix. The distribution of the abundances in the [M + nH]+ peak group varied noticeably for different derivatives. This indicated different levels of the reduction depending on the different structure variations of the studied molecules. In the search for correlations between the mass spectral pattern and the structural features of the dyes, ab initio HF/6-31++G** quantum chemical calculations were performed. They revealed that the abundances of the [M + 2]+, and [M + 3]+ ions show growth proportional to the decrease of the energy of the lowest unoccupied molecular orbital, i.e. proportional to the increase of the electron affinity of the dye molecule. A method for rapid screening of reductive properties of sets of dye derivatives on the basis of the FAB mass spectral data is discussed. Copyright © 2005 John Wiley & Sons, Ltd. [source] Phase behavior and photo-responsive studies of photoactive liquid crystalline hyperbranched polyethers containing benzylidene moietyJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 11 2009V. Srinivasa Rao Abstract Two sets of hyperbranched polyether epoxies were synthesized to study the effect of substituent, rigidity, and nature of photoactive unit on the thermal and photoresponsive properties. Each set was comprised of one molecule with an acyclic moiety in the repeating unit, and two molecules with a cyclic moiety of varying rigidity (cycle size) in the repeating unit. Two substituents on aromatic rings in the repeating unit were present in one set, and other set was without a substituent. The mesogenic and photoresponsive properties were studied and correlated to the varied structural parameters. The effects of varied molecular structural parameters on phase behavior and photoresponsive properties were very prominent. Out of six monomeric diols, only four have exhibited liquid crystalline phase while the polymers corresponding to all monomeric diols revealed mesophase. The findings in photoresponsive properties were further supported by molecular modeling studies. The changes in refractive index, photoviscosity, and fluorescence intensity with irradiation time substantiated the spectral pattern observed in UV-Vis spectroscopy. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2774,2786, 2009 [source] A physiochemical theory on the applicability of soft mathematical models,experimentally interpretedJOURNAL OF CHEMOMETRICS, Issue 7-8 2010L. Munck Abstract An extension of chemometric theory was experimentally explored to explain the physiochemical basis of the very high efficiency of soft modelling of data from nature. Soft modelling in self-organisation was interpreted by studying the unique chemical patterns of mutants in an isogenic barley model on endosperm development. Extremely reproducible, differential Near Infrared (NIR) spectral patterns specifically overviewed the effect on cell composition of each mutant cause. Extended Canonical Variates Analysis (ECVA) classified spectra in wild type, starch and protein mutants. The spectra were interpreted by chemometric data analysis and by pattern inspection to morphological, genetic, molecular and chemical information. Deterministic chemical reactions were defined in the glucan pathway. A drastic mutation in a gene controlling the starch/ß-glucan composition changed water activity that introduced a diffusive, stochastic effect on the catalysis of all active enzymes. ,Decision making' in self-organisation is autonomous and performed by the soft modelling of the chemical deterministic and stochastic reactions in the endosperm cell as a whole. Uncertainty in the analysis of endosperm emergence was experimentally delimited as the ,indeterminacy' in local molecular path modelling ,bottom up' and the ,irreducibility' of the phenomenological NIR spectra ,top down'. The experiment confirmed Ilya Prigogine's interpretation of self-organisation by his dynamic computer model programmed with a self-modeled non-local extension of quantum mechanics (QM). The significance of self- organisation explained by Prigogine here interpreted as physiochemical soft modelling introduces a paradigm shift in macroscopic science that forwards a major argument for soft mathematical modelling and chemometrics to obtain full scientific legitimacy. Copyright © 2010 John Wiley & Sons, Ltd. [source] Tikhonov regularization in standardized and general form for multivariate calibration with application towards removing unwanted spectral artifactsJOURNAL OF CHEMOMETRICS, Issue 1-2 2006Forrest Stout Abstract Tikhonov regularization (TR) is an approach to form a multivariate calibration model for y,=,Xb. It includes a regulation operator matrix L that is usually set to the identity matrix I and in this situation, TR is said to operate in standard form and is the same as ridge regression (RR). Alternatively, TR can function in general form with L,,,I where L is used to remove unwanted spectral artifacts. To simplify the computations for TR in general form, a standardization process can be used on X and y to transform the problem into TR in standard form and a RR algorithm can now be used. The calculated regression vector in standardized space must be back-transformed to the general form which can now be applied to spectra that have not been standardized. The calibration model building methods of principal component regression (PCR), partial least squares (PLS) and others can also be implemented with the standardized X and y. Regardless of the calibration method, armed with y, X and L, a regression vector is sought that can correct for irrelevant spectral variation in predicting y. In this study, L is set to various derivative operators to obtain smoothed TR, PCR and PLS regression vectors in order to generate models robust to noise and/or temperature effects. Results of this smoothing process are examined for spectral data without excessive noise or other artifacts, spectral data with additional noise added and spectral data exhibiting temperature-induced peak shifts. When the noise level is small, derivative operator smoothing was found to slightly degrade the root mean square error of validation (RMSEV) as well as the prediction variance indicator represented by the regression vector 2-norm thereby deteriorating the model harmony (bias/variance tradeoff). The effective rank (ER) (parsimony) was found to decrease with smoothing and in doing so; a harmony/parsimony tradeoff is formed. For the temperature-affected data and some of the noisy data, derivative operator smoothing decreases the RMSEV, but at a cost of greater values for . The ER was found to increase and hence, the parsimony degraded. A simulated data set from a previous study that used TR in general form was reexamined. In the present study, the standardization process is used with L set to the spectral noise structure to eliminate undesirable spectral regions (wavelength selection) and TR, PCR and PLS are evaluated. There was a significant decrease in bias at a sacrifice to variance with wavelength selection and the parsimony essentially remains the same. This paper includes discussion on the utility of using TR to remove other undesired spectral patterns resulting from chemical, environmental and/or instrumental influences. The discussion also incorporates using TR as a method for calibration transfer. Copyright © 2006 John Wiley & Sons, Ltd. [source] Performance Evaluation of the Scent Transfer UnitÔ (STU-100) for Organic Compound Collection and ReleaseJOURNAL OF FORENSIC SCIENCES, Issue 4 2006Brian A. Eckenrode Ph.D. ABSTRACT: The Scent Transfer UnitÔ (STU-100) is a portable vacuum that uses airflow through a sterile gauze pad to capture a volatiles profile over evidentiary items for subsequent canine presentation to assist law enforcement personnel. This device was evaluated to determine its ability to trap and release organic compounds at ambient temperature under controlled laboratory conditions. Gas chromatography-mass spectrometry (GC-MS) analyses using a five-component volatiles mixture in methanol injected directly into a capture pad indicated that compound release could be detected initially and 3 days after the time of collection. Additionally, 15 compounds of a 39-component toxic organic gaseous mixture (10,1000 parts per billion by volume [p.p.b.v]) were trapped, released, and detected in the headspace of a volatiles capture pad after being exposed to this mixture using the STU-100 with analysis via GC-MS. Component release efficiencies at ambient temperature varied with the analyte; however, typical values of c. 10% were obtained. Desorption at elevated temperatures of reported human odor/scent chemicals and colognes trapped by the STU-100 pads was measured and indicated that the STU-100 has a significant trapping efficiency at ambient temperature. Multivariate statistical analysis of subsequent mass spectral patterns was also performed. [source] Characterization of metabolites of tanshinone IIA in rats by liquid chromatography/tandem mass spectrometryJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 5 2006Peng Li Abstract The metabolism of tanshinone IIA was studied in rats after a single-dose intravenous administration. In the present study, 12 metabolites of tanshinone IIA were identified in rat bile, urine and feces with two LC gradients using LC-MS/MS. Seven phase I metabolites and five phase II metabolites of tanshinone IIA were characterized and their molecular structures proposed on the basis of the characteristics of their precursor ions, product ions and chromatographic retention time. The seven phase I metabolites were formed, through two main metabolic routes, which were hydroxylation and dehydrogenation metabolism. M1, M4, M5 and M6 were supposedly tanshinone IIB, hydroxytanshinone IIA, przewaquinone A and dehydrotanshinone IIA, respectively, by comparing their HPLC retention times and mass spectral patterns with those of the standard compounds. The five phase II metabolites identified in this research were all glucuronide conjugates, all of which showed a neutral loss of 176 Da. M9 and M12 were more abundant than other identified metabolites in the bile, which was the main excretion path of tanshinone IIA and the metabolites. M12 was the main metabolite of tanshinone IIA. M9 and M12 were proposed to be the glucuronide conjugates of two different semiquinones and these semiquinones were the hydrogenation products of dehydrotanshinone IIA and tanshinone IIA, respectively. This hydrogenized reaction may be catalyzed by the NAD(P)H: quinone acceptor oxidoreductase (NQO). The biotransformation pathways of tanshinone IIA were proposed on the basis of this research. Copyright © 2006 John Wiley & Sons, Ltd. [source] Raman spectroscopic study of the vivianite arsenate mineralsJOURNAL OF RAMAN SPECTROSCOPY, Issue 10 2003Ray L. Frost Abstract The molecular structures of the vivianite-type arsenate minerals were studied using a combination of Raman and infrared spectroscopy. The Raman spectra of the hydroxyl-stretching regions are complex with overlapping bands at 3419, 3209, 3185 and 3010 cm,1. This complexity is reflected in the water HOH bending modes with strong infrared bands in the 1660,1685 cm,1 region indicating strong hydrogen bonding to arsenate anions in adjacent layers. The Raman arsenate AsO stretching region shows strong similarity between the vivianite arsenate minerals. In the infrared spectra complexity exists with multiple antisymmetric stretching vibrations observed, indicating a reduction of symmetry. Strong infrared bands around 700 and 560 cm,1 are attributed to librational modes of water. Vibrational spectra enable the structure of the minerals to be determined and, whilst similarities exist in the spectral patterns, sufficient differences exist to determine the identification of the minerals. In particular, Raman spectroscopy assists in the identification of the complex isomorphous substitution in these vivianite arsenate minerals. Copyright © 2003 John Wiley & Sons, Ltd. [source] 1H- and 31P-MR spectroscopy of primary and recurrent human brain tumors in vitro: malignancy-characteristic profiles of water soluble and lipophilic spectral componentsNMR IN BIOMEDICINE, Issue 5 2001Fritz-Georg Lehnhardt Abstract In vitro NMR spectrocopy was performed on specimen of human brain tumors. From all patients, tissue samples of primary tumors and their first recurrences were examined. 31P- and 1H-spectra were recorded from samples of meningioma, astrocytoma and glioblastoma. A double extraction procedure of the tissue samples permitted acquisition of information from the membrane fraction and from the cytosolic fraction. 31P-spectra were used to analyze the lipophilic fraction (phospholipids of the membrane) of the tissue extracts, while the 1H-spectra reflected information on the metabolic alterations of the hydrophilic, cytosolic fraction of the tissue. The tumor types showed distinctive spectral patterns in both the 31P- and the 1H-spectra. Based on the total detectable 31P signal, the level of phosphatidylcholine was about 34% lower in primary astrocytomas than in primary glioblastomas (p,=,0.0003), whereas the level of sphingomyelin was about 45% lower in primary gioblastomas than in primary astrocytomas (p,=,0.0061). A similar tendency of these phospholipids was observed when comparing primary and recurrent astrocytoma samples from the same individuals [+15% (p,=,0.0103) and ,23% (p,=,0.0314) change, respectively]. 1H-spectra of gliomas were characterized by an increase of the ratios of alanine, glycine and choline over creatine as a function of the degree of malignancy. In agreement with findings in the 31P-spectra, the 1H-spectra of recurrent astrocytomas showed metabolic profiles of increased malignancy in comparison to their primary occurrence. Since gliomas tend to increase in malignancy upon recurrence, this may reflect evolving tumor metabolism. 1H-spectra of meningiomas showed the highest ratio of alanine over creatine accompanied by a near absence of myo-inositol. Phospholipid profiles of meningiomas showed higher fractional contents of phosphatidylcholine along with lower phosphatidylserine compared to astrocytomas, while higher phosphatidylethanolamine and sphingomyelin fractional contents distinguished meningiomas from glioblastomas. The extraction method being used in this study combined with high-resolution 1H- and 31P-MRS provides a wide range of biochemical information, which enables differentiation not only between tumor types but also between primary and recurrent gliomas, reflecting an evolving tumor metabolism. Copyright © 2001 John Wiley & Sons, Ltd. [source] Analysis of protein profiles of genetically modified potato tubers by matrix-assisted laser desorption/ionization time-of-flight mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 5 2003M. Careri Traceability of genetically modified (GM) foods demands the development of appropriate reliable techniques in order to identify and quantify peptide or nucleic acid residues in GM plants and food products through the food chain. In this study the applicability of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) was demonstrated for the characterization of proteins of transformed and untransformed potato (Solanum Tuberosum L.) tubers. In GM tubers the expression level of the G1-1 gene, which regulates transition from dormancy to sprouting tubers, was inhibited by antisense technology. The analysis of antisense transformed lines showed that several of them exhibited a significant delay in sprouting relative to the control lines, in accordance with a decrease in the transcript level. Preliminary attempts to compare the protein patterns obtained from transformed and control lines using traditional electrophoresis were not able to reveal differences in the low-kDa range. Instead, MALDI-TOFMS applied to total peptide extract without any purification was able to distinguish spectral patterns of transformed and untransformed lines. In particular, several characteristic peaks from m/z 4373 to 4932 were detected only in the mass spectra of GM tuber samples. Copyright © 2003 John Wiley & Sons, Ltd. [source] | |||||||||||||