Reference Band Research Articles

Age-Related Reference Ranges for Growth Parameters

We propose an approach to the computation of age-related reference ranges which guarantees that the proportion of sampled data points covered by the reference band has an arbitrarily specified value. Unlike other approaches in the literature, this method does not have to rely on parametric distributional assumptions. The boundaries of the bands are given by smooth curves, and for modeling the mean as a function of age, a sufficiently flexible class of monotonically increasing functions is used, since in the applications all measured variables are biological growth parameters. The width of the reference band is allowed to be proportional to any suitably fixed function of age which we propose in practice to be taken linear. The approach is illustrated by examples from a large-scale study of the distribution of fetal size measurements obtained by routine prenatal sonography.

Determination of Molecular Spatial Orientation on Polymeric Surfaces Using Internal Total Reflection Infrared Dichroism

A simple arithmetic procedure is developed so as to be able to band-ratio dichroic measurements from ATR-IR spectroscopy to measure the surface molecular orientation of any polymer showing dichroism. This development eliminates the need to get a reproducible contact area or a reference band which does not show dichroism upon drawing

Structural analysis of polyamide-6,6 reinforced with glass fibre by the use of Fourier transform infra-red spectroscopy with photoacoustic detection and differential scanning calorimetry

The effect of fibre reinforcement, industrial processing and subsequent annealing on the structure of polyamide-6,6 was analysed in this paper from the correlation between photoacoustic Fourier transform infra-red (PA FTi.r.) spectroscopic and differential scanning calorimetry (d.s.c.) thermal measurements. Using the band situated at 1650 cm −1 as an internal reference band, no spectral change was detected in the bands at 936 and 1146 cm −1. Furthermore, the bands centred at 1335 and 1224 cm −1, which are related to chain-folding, appear in the unannealed composite, whereas in the matrix these were only detected at the highest annealing temperatures. It seems that the manufacturing process used for the composite determines its microstructure and the subsequent annealing does not produce further conformational changes. On the other hand, the composite satisfies a two-phase conformational model, different from that of the matrix, which can be related to the strong interactions between the polymer and the glass fibres with surface treatment. In the thermal analysis, in contrast to the spectroscopic results, substantial changes in the endothermic melting peaks and in the degree of crystallinity can be noted. Up to an annealing temperature of ∼ 120–150°C, the composite crystallinity is constant and lower than the matrix crystallinity, but above this temperature the value rises and tends towards the values of the matrix. Furthermore, there was a more homogeneous crystalline distribution detected in the unannealed matrix, along with a greater size and perfection of the crystals than that seen in those of the unannealed composite. We suggest that the d.s.c. variation in the crystallinity can be attributed to an improvement in the fibre-matrix interface, in which the crystals of the interfacial phase change to more perfect ones as a result of the annealing treatment.

Rapid diagnosis of schistosomiasis by antigen detection in urine with a reagent strip

For the rapid and simple diagnosis of schistosomiasis, a reagent strip assay for detection of circulating cathodic antigen (CCA) in urine was developed. The test was based on a previously developed sandwich enzyme-linked immunosorbent assay (ELISA) using a combination of two anti-CCA monoclonal antibodies. For the reagent strip assay, as the capture matrix, monoclonal antibody was coated onto a nitrocellulose membrane and mounted on polyvinyl chloride strips. Urine samples were then tested in an assay consisting of a combined incubation step of the urine sample and biotinylated detecting antibody followed by incubation in streptavidin peroxidase and a subsequent staining. The specificity and the sensitivity of the assay, as determined with urine samples of 61 uninfected controls and 67 Schistosoma mansoni-infected individuals, were 96.7 and 95.5%, respectively. The results of the reagent strip assay compared very well with microscopical parasitological diagnosis by the standard Kato-Katz method for the same individuals. The reagent strip test has a lower detection limit of 1 ng of CCA per ml and can be completed in 75 min. By the inclusion of two reference bands on the strips, standardized reading could be achieved. This reagent strip assay is a promising tool for qualitative diagnosis of S. mansoni infections in control programs.

Structural analysis of injection-moulded semicrystalline polymers by Fourier-transform infra-red spectroscopy with photoacoustic detection and differential scanning calorimetry: 2. Polyamide-6,6

In this paper, a study of the structural changes due to annealing of injection-moulded polyamide-6,6 has been carried out. The spectroscopic behaviour of polyamide-6,6 is quite similar to that of poly(ethylene terephthalate) (PET). Using the band at 1650 cm −1 as an internal reference band, the intensity changes of the bands situated at 1146 and 936 cm −1 were followed. The former decreases when the annealing temperature exceeds 180°C whereas the latter increases. Furthermore, the bandwidth of the band at 936 cm −1 decreases from 23 to 20 cm −1 for annealing above 180°C. These spectroscopic changes were related to gauche/trans isomerism induced by the thermal treatment. Moreover, polyamide-6,6 verifies a two-phase conformational model, similarly to PET. As far as the thermal behaviour is concerned, two endothermic peaks at low (LM peak) and high (HM peak) temperature were found in thermograms of samples annealed above 150°C, and these displayed similar behaviour to those found in PET. The LM peak can be attributed to melting of crystals with increasing perfection and fold-surface smoothing of the crystalline layers due to the annealing treatment, and the HM peak to melting of the recrystallized crystalline structure during heating in differential scanning calorimetry (d.s.c.). On the other hand, the influence of the fabrication process in polyamide-6,6 seems not to be as important as in PET. The correlation between Fourier-transform infra-red spectroscopy with photoacoustic detection (p.a.- FTi.r.) and d.s.c. measurements show that the amide group works as an important constraint that limits the mobility of the crystalline molecules, and most of the conformational changes occur in the amorphous phase for annealing temperatures above 180°C. In the ordered phase, a slight crystallinity increase beyond this temperature can be related to crystalline perfection and fold-surface smoothing.

Polarized internal reflectance spectroscopic studies of oriented poly(ethylene terephthalate)

AbstractPolarized internal reflectance spectroscopy (IRS) has been used to evaluate molecular orientation and crystallinity of poly(ethylene terephthalate) film surfaces. Measurements were taken using samples stretched in both uniaxial and biaxial modes. All bands of interest were normalized with a reference band near 1410 cm−1, resulting from phenylene ring vibrations. Normalization was performed in order to overcome problems with sample contact and effective thickness. Results obtained using bands representing trans and gauche rotational isomers, present, respectively, at 1340 and 1370 cm−1, have been related to data acquired using density and birefringence techniques. The polarized IRS technique discussed is well suited for investigations of polymer orientation and crystallinity, since it avoids limitations related to sample thickness and clarity imposed by polarized transmission infrared spectroscopy. Parameters such as orientation functions, attenuation indices, dichroic ratios, and structural factors have been determined from data collected in each of the three spatial directions. Results are correlated with corresponding density, birefringence, and refractive index values and are found to give good agreement with these methods. © 1994 John Wiley & Sons, Inc.

Investigation of melamine-formaldehyde cure by Fourier transform Raman spectroscopy

Fourier transform (FT) Raman spectroscopy has been used for characterization of melamine-formaldehyde (MF) resins. Band assignments were based on a combination of literature band assignments, a study of the Raman spectra of model compounds and well characterized MF adducts and resins. The triazine ring breathing band at 975 cm −1 and the C-H stretching bands around 3000 cm −1 can be used as internal reference bands in the Raman spectra of MF resins. It is shown that FT-Raman spectroscopy, in combination with 13C nuclear magnetic resonance and liquid chromatography can bring further elucidation on the methylolation and ether- and methylene-bridge formation in (cured) MF resins.

Photoluminescence of heavily Zn-doped Ga0.85In0.15As grown by low-pressure metalorganic vapor phase epitaxy

Zn-doped, p-type, Ga0.85In0.15As samples grown by low-pressure metalorganic vapor phase epitaxy, with free carrier concentrations in the range of 3.22×1015–1.95×1020 cm−3, have been studied by photoluminescence as a function of temperature. At low doping levels, recombinations involving discrete impurity states and free excitons provided a measurement of both the 0 K reference band gap, Eg(0)=(1.296±0.003) eV, and of the Zn acceptor binding energy, E(Zn0)=(25±3) meV in the Ga0.85In0.15As alloy. High doping concentrations cause a band gap shrinkage ‖ΔEg‖ which has been observed with photoluminescence experiments. A model taking into account Kane band tails and assuming a constant matrix element for the relevant optical transitions has been fitted to the photoluminescence spectra of layers with doping levels in the range of 1.6×1019–1.95×1020 cm−3. This provided a good description of the experimental results. The 0 K band gap shrinkage, which appeared to be smaller than in GaAs, follows the relation ‖ΔEg‖=1.4×10−8p1/3 for Ga0.85In0.15As, with ‖ΔEg‖ in eV and p in cm−3.

Fourier deconvolution of infrared spectra using a reference band

A method of Fourier deconvolution of infrared (IR) spectra using a reference band is developed. The deconvolution function is given by an expression of the type exp[−(Δ x) ρ], where Δ is the deconvolution half-width and the parameter ρ is determined by the experimental reference band shape. The specific experimental conditions are additionally taken into account by the ratio R( x), in which deconvolution function is modified with the normalized experimental interferogram of the reference spectrum. The proposed procedure allows overdeconvolution to be controlled. The reference band is selected either from the IR spectrum being studied or from the spectrum of another compound. Two principal restrictions are included: the reference band should be symmetric and must be recorded under the same conditions as the IR spectrum, subject to the deconvolution.

Application of ATR-IR to the Analysis of Surface Structure and Orientation in Uniaxially Drawn Poly(Ethyleneterephthalate)

A critical examination of the use of ATR-IR for the examination of surface composition and orientation in uniaxially drawn poly(ethyleneterephthalate) (PET) films has been performed. This work has identified the band at 1410 cm−1 as a satisfactory reference band in ATR-IR analyses for surface composition and orientation analyses in oriented PET films. Other commonly used reference bands at 790 and 1510 cm−1 have been shown to be influenced by both incident infrared polarization and orientation within the polymer films. Control of sample clamping pressure in a conventional ATR-IR clamp has been shown to afford optimized sample contact, needed in conjunction with the use of valid reference bands to obtain reproducible in-plane surface dichroism measurements of films with varying degrees of orientation.

Solid state quantum yield determination of a novel base photogenerator

The photoefficiency of a new class of base photogenerating materials, based on the photoremoval of the α,α-dimethyl-3,5-dimethoxybenzyloxycarbonyl (Ddz) group from masked amine-type bases, was investigated. The solid state quantum yield for the photogeneration of cyclohexylamine from its corresponding Ddz carbamate was evaluated at 280 nm using a number of quantitative IR methods. A value of 0.10 was found using the optimal method involving a comparison of the intensities of a strong IR reference band solely associated with the polymer matrix with the decreasing carbonyl absorption of the Ddz substrate. Comparable quantum yields were also found by using an intense band associated with the Ddz-masked amine, thus indicating the overall applicability and reliability of the method provided that careful choice of the reference band was made. The value of the quantum efficiency for the photodeprotection of Ddz-masked amines is sufficiently high for practical applications requiring the use of photogenerated base.

Diagnosis of infective and inflammatory disorders by flow cytometric analysis of blood neutrophils.

The utility of neutrophil parameters provided by two flow cytometric hematologic analyzers (the H-1 and H6000, Technicon Instruments Corporation, Tarrytown, NY) was investigated for the diagnosis of infective and/or inflammatory disorders. The test population of 156 hospital patients was selected on the basis of a blood culture request. Positivity or negativity for infective and/or inflammatory disease was inferred from chart review. The parameters evaluated included the absolute neutrophil count, the lobularity index, and the left shift flag from the H-1, the percentage of high peroxidase cells from the H6000, the routine laboratory band count, and a reference band count. Significant intercorrelations were observed between these parameters. The diagnostic performance of the routine laboratory band count was significantly inferior to that of all other parameters. At equivalent points on their receiver operating characteristic curves, the diagnostic efficiencies of the remaining tests ranged from 61.5% for the lobularity index to 67% for the left shift flag and the percentage of high peroxidase cells. These differences were not significant statistically.

Intensity measurement of resonance Raman spectra of dye solutions with the divided Raman cell

AbstractThe resonance Raman intensities of methyl orange and brilliant blue FCF in aqueous solutions were measured by using a rotating divided Raman cell which provides an external intensity standard. The logarithms of the apparent intensities of the sample bands revealed a good linear dependence on the light path length. The relative Raman scattering coefficients of the samples with respect to a common reference band were determined from the intercepts. The effects of the excitation wavelength and the presence of surfactant on the apparent Raman intensities and the relative Raman scattering coefficients are discussed.

Barley Cultivar Identification by Polycrylamide Gel Electrophoresis of Hordein Proteins: Catalog of Cultivars1

Polyacrylamide gel electrophoresis (PAGE) of hordein polypeptides was used to identify and catalog barley (Hordeum vulgare L.) cultivars. An electrophoregram formula was prepared for each cultivar using relative band mobility (based on the ‘Betzes’ reference band 0.50). Forty cultivars were separated into 17 groups. Group was largest with 12 cultivars, six other groups contained more than one cuitivar, and only 10 cultivars showed unique hordein band patterns. Some differences, mainly due to presence or absence of faint bands, were observed among cultivars within groups. It was possible to differentiate cultivars currently grown in North Dakota into five groups which included: 1) ‘Glenn’, ‘Morex’, ‘Robust’, ‘Hazen’, and ‘Bumper’; 2) ‘Azure’; 3) ‘Larker’; 4) ‘Bedford’; and 5) ‘Hector’. Banding patterns of Glenn, Morex, Robust, Hazen, and Bumper were identical. The malting cultivars Robust and Morex and the feed types Bedford and ‘Klondike’ have similar kernel characteristics. Using PAGE, it was possible to differentiate the two malting types from the two feed types and also differentiate between Bedford and Klondike. Also, hordein band patterns of six single kernels from each of 38 cultivars were compared with a meal sample from each cultivar with Betzes as a reference. In general, single kernels gave hordein band patterns identical to those of meal samples, but intensity of bands usually was fainter. Single kernels gave better resolution than meal samples. Of the cultivars analyzed, 25 showed identical hordein band patterns in single kernels and their corresponding meal samples, while 13 showed differences between their meal and/or among single kernel bands.

Spatial Sharpening Of Thematic Mapper Data Using A Multiband Approach

A new image enhancement technique has been applied to enhance Landsat-4 Thematic Mapper (TM) thermal infrared (IR) imagery and has improved its effective ground resolution from 120 m to 30 m. The technique is based on an adaptive multiband least squares (LS) method for computing an optimal image estimate from reference images, and a frequency domain replacement step. The approach relies on the assumption that at a sufficiently small resolution registered TM imagery data are locally correlated across the bands. Using the local correlation property, visible and IR reference bands are used to predict the thermal IR image data. The prediction estimate is then used to augment the spatial high frequency information in the original thermal data. Preliminary experiments enhancing 120 m IR imagery (simulated degradation) to 30 m resolution show a signal-to-noise ratio improvement of 19 dB.

The Influence of Experimental Conditions in Quantitative Analysis of Powdered Samples by Fourier Transform Infrared Photoacoustic Spectroscopy

Photoacoustic Spectroscopy (PAS) is now well-established as a useful technique for obtaining optical absorption spectra from strongly scattering and/or opaque materials which are difficult to study by conventional photometric methods. However, its quantitative application to solids in the UV-visible region has been somewhat restricted by the phenomenon of photoacoustic (PA) signal saturation, in which the intensity of the stronger bands in the spectrum becomes insensitive to changes in analyte concentration. By comparison, with the recent advent of Fourier Transform Infrared Photoacoustic Spectroscopy (FT-IR/PAS), this problem is expected to be much less serious in view of the low absorptivities characteristic of IR bands. Indeed, recent work in our laboratory has shown that when NH3 is sorbed stepwise into the bulk of 12-tungstophosphoric acid, H3PW12O40, the base is quantitatively converted to NH4+ ion, and the calibration curve of the analyte peak area (standardized against a reference band of the substrate) vs. analyte concentration is virtually linear up to stoichiometric loading. With the use of this method, several salts of the parent acid were found to exist in partial (Bronsted) acid form, and adjusted molecular formulae thus calculated were consistent with those obtained in dependently by elemental analysis.

WHEAT CULTIVAR IDENTIFICATION BY GLIADIN ELECTROPHOREGRAMS. I. APPARATUS, METHOD AND NOMENCLATURE

An apparatus and method are described for polyacrylamide gel electrophoresis of gliadins. Since the gliadin pattern (electrophoregram) is a genotypic character, electrophoresis offers a promising means for identifying wheat cultivars. Electrophoregrams are presented for a number of wheat cultivars to illustrate the results that can be obtained by the method described. A new nomenclature for gliadin bands (components) separated by this method is also presented. The nomenclature uses a major band in the electrophoregram of the Canadian hard red spring wheat cultivar Marquis as the reference. It was assigned an arbitrary mobility of 0.50; all other bands of Marquis and other cultivars are identified on the basis of electrophoretic mobility relative to 0.50 for the reference band under identical electrophoresis conditions.

Spectrophotometric determinations of aryldiazonium salts of complex halides used as photoinitiators in u.v.-cured epoxide systems

Methods for the determination of aryldiazonium salts of complex halides are reported. These salts serve as photoinitiators of polymerization in thin films of u.v.-cured epoxides and in coating solutions. The methods can be applied at the 0.5–4.0 wt.-% level, for determining the quantum yields of photolyses of initiators such as aryldiazonium hexafluorophosphate and tetrafluoroborate. Thin films on reflective substrates are analyzed by spectroreflectometry and films on transparent substrates are analyzed by transmission. An absorbance ratio calculation is used so that the methods are independent of variations in film thickness. Significant analytical bands are the diazonium band at 280–403 nm, depending on the specific initiator, and a series of internal reference bands of the polymer which absorb in different regions of the- u.v. and i.r. spectra. The coating solutions are monitored by a differential i.r. method sensitive to less than 0.04 wt.-% of the initiator in a multicomponent system.

Die rotationsisomerie des bicyclopropyls.: II . Die gauche/trans-isomerisierungsenthalpie und-entropie von bicyclopropyl aus ir-intensitäts-messungen. Ein experimenteller test

The determination of the enthalpy Δ H and entropy Δ S of the isomerization bicyclopropy l( trans)⇌ bicyclopropyl( gauche) in the liquid phase by the IR intensity method is described. It is assumed that the ratio of the integral absorption coefficients of the two reference bands at 1351 cm −1 ( gauche) and 1291 cm −1 ( trans), which both belong to the same type of vibration, is temperature independent. The two values Δ H = −160 ± 40 cal Mol −1 and Δ S = −0.4 ± 0.5 cal (Mol · Grad) −1 respectively. Δ S U = −1.8 ± 0.5 cal (Mol · Grad) −1 thus determined agree well with the corresponding results obtained from NMR and electron diffraction measurements. However, from the pair of reference bands at 695 cm −1 ( gauche) and 1291 cm −1 ( trans), which do not belong to the same type of vibration, strongly differing values for Δ H and Δ Sresult under the same assumption as above, which apparently is not applicable in this case. It is shown through these data that the “Fateley-Test” does not provide a suitable tool to decide whether the absorption coefficients of the reference bands are temperature independent or not. The reason for this insignificance is the relatively poor accuracy and reproducibility of measured IR band intensities obtainable up to now. The relative density of bicyclopropyl between −60°C and + 50°C was determined.

Über die bestimmung von isomerisierungsenthalpien und -entropien mit der IR-intensitätsmethode

Among the many sources of error which may affect the results for the enthalpy Δ H and entropy Δ S of isomerization determined by the IR-intensity method, the influence of the temperature dependence of the absorptivities of the reference bands, α g( T) and α t ( T), is studied theoretically. Based on the general case I, the following three special cases II–IV are examined, in which increasingly stronger constraints are imposed on the compound-specific functions α g ( T) and α T ( T): II. Constant ratio α g ( T)/α T ( T), III. α g ( T) and α T ( T) both temperature independent and different, IV. α g ( T) and α T ( T) both temperature independent and equal. For each case the formulae for the evaluation of Δ H and Δ S as well as the kind and the number of the quantities to be measured are given. Moreover, in the cases I and II new methods for the analysis of the measured data are suggested. In each case the plots of the normalized band intensities A g and A t and the temperature T versus each other in different two-dimensional diagrams have been examined to find out whether one of the simpler special cases is applicable for the respective pair of reference bands. It is shown that these plots are not a suitable tool because of the relatively poor accuracy and reproducibility of measured IR-band intensities obtainable up to now.