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Band Profiles (band + profile)

Distribution by Scientific Domains

Life Sciences	40%
Chemistry	20%

Selected Abstracts

Prediction of Band Profiles of Mixtures of Bradykinin and Kallidin from Data Acquired by Competitive Frontal Analysis

BIOTECHNOLOGY PROGRESS, Issue 3 2003
Dongmei Zhou
The competitive adsorption isotherms of two closely related peptides, bradykinin and kallidin, were measured by frontal analysis on a Zorbax SB-C18 microbore column. An aqueous soluton at 20% acetonitrile (0.1% TFA) was used as the mobile phase. The competitive isotherm data were fitted to four different models: Langmuir, Bilangmuir, Langmuir-Freundlich, and Toth. These data fitted best to a Bilangmuir isotherm model. The influence of the pressure on the retention factors of the two peptides was found to be small and was not investigated in detail. The band profiles of large samples of the single components and of their mixtures were recorded. The overloaded profiles calculated using either the equilibrium-dispersive or POR model are in excellent agreement with the experimental profiles in all cases. Our results confirm that the competitive isotherm data derived from mixtures may suffice for a reasonably accurate prediction of the band profiles of all mixtures of the two components, provided their composition is close to 1/1. [source]

Raman spectroscopy of dimethyl sulphoxide and deuterated dimethyl sulphoxide at 298 and 77 K

JOURNAL OF RAMAN SPECTROSCOPY, Issue 2 2002
Wayde N. Martens
Raman spectroscopy was used to determine the molecular behaviour of DMSO and DMSO- d6, and to compare it with that of DMSO in DMSO-intercalated kaolinites. For DMSO at 298 K two bands are observed at 2994 and 2913 cm,1 and are assigned to the antisymmetric and symmetric CH stretching modes. At 77 K the degeneracy of these bands is lost. Bands are now observed as antisymmetric bands at 3001, 2995 and 2988 cm,1 and symmetric bands at 2923, 2909 and 2885 cm,1, respectively. For the DMSO-intercalated low-defect kaolinite, the 2913 cm,1 band resolves into five component bands at 2882, 2907, 2917, 2920 and 2937 cm,1. The CD antisymmetric and symmetric stretching modes in the 298 K spectrum are found at 2250 and 2125 cm,1, respectively. Both bands show some asymmetry and further bands may be resolved at 2256 and 2244 cm,1 in the antisymmetric stretching region and at 2118 cm,1 in the symmetric stretching region. The spectra of the SO stretching region of DMSO and DMSO- d6 are complex with a band profile centred at 1050 cm,1. Three bands are curve resolved at 1058, 1042 and 1026 cm,1 attributed to the unassociated monomer and the out-of-phase and the in-phase vibrations of the dimer, respectively. Upon cooling to liquid nitrogen temperature, these three bands are observed at 1057, 1038 and 1019 cm,1. The spectra of the SO stretching region of DMSO- d6 are more complex because of the overlap of the DCD deformation modes with the SO stretching modes. The antisymmetric and symmetric stretching CS modes of DMSO are observed at 698 and 667 cm,1, shifting at 77 K to 705 and 672 cm,1. It is concluded that the structure of DMSO in DMSO-intercalated kaolinite is different from those of both liquid DMSO at 298 K and solid DMSO measured at 77 K. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Monitoring of biomass composition from microbiological sources by means of FT-IR spectroscopy

BIOTECHNOLOGY & BIOENGINEERING, Issue 1 2009
Arthur M.A. Pistorius
Abstract An FT-IR spectroscopic method was developed for the simultaneous quantitative analysis of biomacromolecular components in biomass, originating from various microbiological sources. For the determination of protein, lipid and carbohydrate content, creatine phosphokinase, egg phosphatidyl choline and starch hydrolysate were chosen as external standards. This selection was based on spectral similarity and ease of availability. Protein content was based on the area under the amide II band profile around 1,545 cm,1. Because of the heterogeneous lipid composition in the different species, lipid content was determined using integration over the CH stretching vibrational population between 2,984 and 2,780 cm,1. Carbohydrate content was determined using integration over a CO and COC stretching band area between 1,180 and 1,133 cm,1. Linear regression analysis provided three calibration lines, according to which biomasses from ten species were analyzed. This approach showed good intra-batch reproducibility. With this method we could demonstrate good reproducibility between batches of the same species with similar growth conditions while large differences in biomass composition were observed between the various species. Protein content as determined by FT-IR spectroscopy compared well with the results obtained from elemental analysis. Biotechnol. Bioeng. 2009;103: 123,129. © 2008 Wiley Periodicals, Inc. [source]

Modeling l-dopa purification by chiral ligand-exchange chromatography

AICHE JOURNAL, Issue 3 2007
Nooshafarin Sanaie
Abstract A model describing elution-band profiles that combines multiple chemical equilibria theory with the nonideal equilibrium,dispersion equation for solute transport is used to predict and characterize the separation of l,d-dopa by chiral ligand-exchange chromatography (CLEC). Formation constants and stoichiometries for all equilibrium complexes formed in the interstitial volume and pore liquid are taken from standard thermodynamic databases and independent potentiometric titration experiments. Formation constants for complexes formed with the stationary phase ligand (N-octyl-3-octylthio-d-valine) are determined from potentiometric titration data for a water-soluble analogue of the ligand. This set of pure thermodynamic parameters is used to calculate the spatially discretized composition of each column volume element as a function of time. The model includes a temperature-dependent pure-component parameter, determined by regression to a single elution band for the pure component, that corrects for subtle effects associated with immobilizing the N-octyl-3-octylthio-d-valine ligand onto the stationary phase. The model is shown to accurately predict elution chromatograms and separation performance as a function of key column operating variables. The model is then used to better understand the connection between chemical equilibria within the system and changes in band profiles and band separation resulting from changes in column operating conditions. © 2007 American Institute of Chemical Engineers AIChE J, 2007 [source]

rpoB -PCR amplified gene and temporal temperature gradient gel electrophoresis: a rapid tool to analyse bacterial strains representative of cold-smoked salmon microflora

LETTERS IN APPLIED MICROBIOLOGY, Issue 2 2004
S. Giacomazzi
Abstract Aim:, To evaluate rpoB gene as a biomarker of microbial biodiversity associated to cold-smoked salmon by a novel nested-polymerase chain reaction/temporal temperature gradient gel electrophoresis (PCR/TTGE) technique applied on pure cultures of reference strains. Methods and Results:, DNA obtained from pure cultures of reference strains was used in a succession of a first PCR amplification of rpoB fragment with degenerated nonclamped primers and a nested-PCR with nondegenerated clamped primers. PCR products were then applied on a TTGE gel in order to analyse strains profile. High quantity of nested-PCR products were obtained for each tested strain and TTGE profiles showed a good separation between the different reference bacteria and an easy way to associate one band to one species. Conclusion:, The nested-PCR/TTGE technique used in this study is a promising way of investigating bacterial community structure of cold-smoked salmon or other food matrix. Significance and Impact of the Study:, Because of its single copy state leading to single band profiles in TTGE, rpoB constitute a good potential molecular marker for further development of cold-smoked salmon biodiversity analysis. [source]

Determination of genomic damage in neuroblastic tumors by arbitrarily primed PCR: MYCN amplification as a marker for genomic instability in neuroblastomas

NEUROPATHOLOGY, Issue 3 2006
Jorge Muñoz
The aim of this study is to establish an estimation of the global genomic alteration in neuroblastic tumors (ganglioneuromas, ganglioneuroblastomas and neuroblastomas) and correlate them with different clinical parameters (age, sex, diagnosis, Shimada index, proliferation index, tumor location, and 1p and v-myc avian myelocitomatosis viral-related (MYCN) status) in order to find new molecular and/or prognostic markers for neuroblastoma. To assess the genomic damage in neuroblastic tumors, we used an arbitrarily primed PCR approach, a technique based on the reproducibility of band profiles obtained by a PCR with a low annealing temperature in its first cycles. Genomic damage was assessed by comparing band profiles of tumors and normal paired samples. Gains and losses in the intensity of the bands were computerized and referred to the total number of bands analyzed. We found a higher genomic damage fraction (GDF) in the female's group (U-Mann,Whitney, P = 0.025), but we could not find any association between GDF and tumor location, proliferation index, diagnosis or age of the patient. There was no relationship between 1p status and GDF, but tumors with MYCN amplification had a slightly higher GDF. MYCN amplification might in some way contribute to genomic instability of neuroblastomas. [source]

Self-consistent calculation for energy band profiles and energy levels of cubic quantum dots

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 14 2005
Johnson Lee
Abstract We have performed a self-consistent calculation for the energy band profiles and energy levels of cubic quantum dots, solving both the Schrödinger and Poisson's equations. In particular, we examined the effect of doping on these levels both in the presence and absence of a positive test charge. We found that the number of levels the cubic dot supported depended on the size of the dot, and that the energy of the levels decreased in the presence of a positive test charge. Moreover, we found that the energy levels of both the singlet and triplet states in the dot increased with the doping density. The quasi-Fermi level was found to be lower in the presence of a positive test charge than in its absence, and the quasi-Fermi level increased sharply with increasing doping density both in the absence and presence of the test charge. With very high doping the Fermi level is located in the barrier while with low doping the Fermi level is located down below the ground state energy which implies that the probability of finding an electron in a dot is very small. We also find that at high doping levels the lowest energy states are no longer confined in the dot. The potential energy profile was found to be dramatically affected by both the doping and the presence of a positive test charge. The profile was found to become asymmetric when the test charge was displaced from the center of the dot. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]