Laser-based Analysis Research Articles

Feline reference intervals for the Sysmex XT-2000iV and the ProCyte DX haematology analysers in EDTA and CTAD blood specimens.

Laser-based haematology analysers are routinely used in veterinary clinical pathology laboratories, and are available to practitioners. However, feline haematological reference intervals (RIs) determined according to international recommendations are, to our knowledge, not available. Furthermore, platelet count RI is difficult to establish in cats because of the frequent occurrence of platelet aggregation in blood specimens. The purpose of this study was to establish feline haematological RIs with the Sysmex XT-2000iV and ProCyte DX analysers, in ethylenediamine tetra-acetic acid (EDTA) and in citrate, theophylline, adenosine and dipyridamole (CTAD), which is a combination of anticoagulants limiting platelet aggregation. Blood specimens from 120 healthy cats were analysed in duplicate, and the degree of platelet aggregation was assessed on blood smears. After exclusion of inadequate specimens, 81 sets of results (from 44 males and 37 females, aged from 6 to 116 months) were available for the determination of RIs by the non-parametric method. The effects of the anticoagulant, analyser and aggregation score were assessed. When the aggregation effect was significant, the RIs were determined using the subgroup of blood specimens with no or little aggregation. The effects of sex, age and weight were also investigated, but were moderate. The different RIs obtained with the Sysmex XT-2000iV and ProCyte DX analysers, and the two anticoagulants, were very similar to previous RIs established in EDTA with the ADVIA 120, another laser-based analyser, except for the platelet count in CTAD specimens. Its lower reference limit was higher in CTAD vs EDTA specimens, which confirms the interest in this anticoagulant in cats.

Evaluation of a new JMA aircraft flask sampling system and laboratory trace gas analysis system

Abstract. We established and evaluated a flask air sampling system on a cargo C-130H aircraft, as well as a trace gas measurement system for the flask samples, as part of a new operational monitoring program of the Japan Meteorological Agency (JMA). Air samples were collected during each flight, between Kanagawa Prefecture (near Tokyo) and Minamitorishima (an island located nearly 2000 km southeast of Tokyo), from the air-conditioning system on the aircraft. Prior to the operational employment of the sampling system, a quality assurance test of the sampled air was made by specially coordinated flights at a low altitude of 1000 ft over Minamitorishima and comparing the flask values with those obtained at the surface. Based on our storage tests, the flask samples remained nearly stable until analyses. The trace gas measurement system has, in addition to the nondispersive infrared (NDIR) and vacuum ultraviolet resonance fluorescence (VURF) analyzers, two laser-based analyzers using wavelength-scanned cavity ring-down spectroscopy (WS-CRDS) and off-axis integrated cavity output spectroscopy (ICOS). Laboratory tests of the laser-based analyzers for measuring flask samples indicated relatively high reproducibility with overall precisions of less than ±0.06 ppm for CO2, ±0.68 ppb for CH4, ±0.36 ppb for CO, and ±0.03 ppb for N2O. Flask air sample measurements, conducted concurrently on different analyzers were compared. These comparisons showed a negligible bias in the averaged measurements between the laser-based measurement techniques and the other methods currently in use. We also estimated that there are no significant isotope effects for CH4, CO and N2O using standard gases with industrial isotopic compositions to calibrate the laser-based analyzers, but CO2 was found to possess isotope effects larger than its analytical precision.

Comparison of the ProCyte Dx analyzer with the ADVIA 2120 and the manual differential for validation of equine and bovine hemograms

The aim of this study was to evaluate the laser-based in-house hematology analyzer ProCyte Dx performing a complete hemogram for bovine and equine blood samples. This is a prospective study of clinically healthy or ill horses (n = 175) and cattle (n = 115). EDTA-anticoagulated blood samples were analyzed within 3–6 h after sampling. Routine hemogram variables including differential counts were compared to reference methods (ADVIA 2120, 200-cell manual differential leukocyte count). Statistical analysis was performed twice, i.e., prior to and after exclusion of specimens with graphical reports (dot plots) indicative of invalid separation of cellular populations. Coefficient of variation was <3 % (CBC) and <7 % (differential count) except for eosinophils and monocytes (cattle) and platelets (PLTs) (horse). Linearity was excellent except for equine platelets. Spearman's rank correlation coefficients (r s) revealed a good to excellent (r s = 0.99–0.80) correlation between both analyzers for the majority of variables except for mean corpuscular hemoglobin concentration (MCHC) (r s = 0.33–0.65), equine platelets assessed with impedance count (r s = 0.79), and monocytes (both species). Biases were close to 0; however, for MCHC, hemoglobin (HGB), and PLTs large biases were seen for both species. There was a favorable correlation with the reference methods for the majority of variables. The large biases of HGB and HGB-derived variables were caused by the methodology of the ADVIA. As for other analyzers, correct PLT and monocyte count are difficult. Dot plot analysis is a useful tool to detect invalid separation of cellular populations and thus the necessity to perform a manual differential count.

Spectral contaminant identifier for off-axis integrated cavity output spectroscopy measurements of liquid water isotopes

Developments in cavity-enhanced absorption spectrometry have made it possible to measure water isotopes using faster, more cost-effective field-deployable instrumentation. Several groups have attempted to extend this technology to measure water extracted from plants and found that other extracted organics absorb light at frequencies similar to that absorbed by the water isotopomers, leading to δ(2)H and δ(18)O measurement errors (Δδ(2)H and Δδ(18)O). In this note, the off-axis integrated cavity output spectroscopy (ICOS) spectra of stable isotopes in liquid water is analyzed to determine the presence of interfering absorbers that lead to erroneous isotope measurements. The baseline offset of the spectra is used to calculate a broadband spectral metric, m(BB), and the mean subtracted fit residuals in two regions of interest are used to determine a narrowband metric, m(NB). These metrics are used to correct for Δδ(2)H and Δδ(18)O. The method was tested on 14 instruments and Δδ(18)O was found to scale linearly with contaminant concentration for both narrowband (e.g., methanol) and broadband (e.g., ethanol) absorbers, while Δδ(2)H scaled linearly with narrowband and as a polynomial with broadband absorbers. Additionally, the isotope errors scaled logarithmically with m(NB). Using the isotope error versus m(NB) and m(BB) curves, Δδ(2)H and Δδ(18)O resulting from methanol contamination were corrected to a maximum mean absolute error of 0.93 [per thousand] and 0.25 [per thousand] respectively, while Δδ(2)H and Δδ(18)O from ethanol contamination were corrected to a maximum mean absolute error of 1.22 [per thousand] and 0.22 [per thousand]. Large variation between instruments indicates that the sensitivities must be calibrated for each individual isotope analyzer. These results suggest that the properly calibrated interference metrics can be used to correct for polluted samples and extend off-axis ICOS measurements of liquid water to include plant waters, soil extracts, wastewater, and alcoholic beverages. The general technique may also be extended to other laser-based analyzers including methane and carbon dioxide isotope sensors.

Sulphur stable isotope systematics in diagenetic pyrite from the North Sea hydrocarbon reservoirs revealed by laser combustion analysis

Our study focuses on pyrite nodules developed in the Brent Group sandstones, which host the Brent Oilfield, one of the North Sea's greatest oil and gas producers. Timing of nodule formation is equivocal, but due to the forceful, penetrative textures that abound, it is considered late. This pyrite offers a research opportunity because it records the development of the supply of H2S in a hydrocarbon reservoir and its sulphur isotopic composition. Laser-based analysis of δ34S reveals an extraordinary diversity in values and patterns. The values range from−27 to+72‰, covering half the terrestrial range, with large variations at the submillimetre scale. Isotopically heavy (δ34S ∼+30‰ or higher) sulphide is endemic, but low δ34S pyrite is also present and appears to represent a temporally though not spatially (on the ∼cm scale) distinct pyritisation event. The distribution of δ34S values within individual concretions can be normal (Gaussian), but in some cases may reflect progressive isotope fractionation process(es), conceivably of Rayleigh type. The source of the sulphur and the identity of the isotope fractionation process(es) remain enigmatic.

Crown plasticity in mixed forests—Quantifying asymmetry as a measure of competition using terrestrial laser scanning

Interspecific competition is a key process determining the dynamics of mixed forest stands and influencing the yield of multispecies tree plantations. Trees can respond to competitive pressure from neighbors by crown plasticity, thereby avoiding competition. We employed a high-resolution ground-based laser scanner to analyze the 3-dimensional extensions and shape of the tree crowns in a near-natural broad-leaved mixed forest in order to quantify the direction and degree of crown asymmetry of 15 trees ( Fagus sylvatica, Fraxinus excelsior, Carpinus betulus) in detail. We also scanned the direct neighbors and analyzed the distance of their crown centres and the crown shape with the aim to predict the crown asymmetry of the focal tree from competition-relevant attributes of its neighbors. It was found that the combination of two parameters, one summarizing the size of the neighbor (DBH) and one describing the distance to the neighbor tree (HD), was most suitable for characterizing the strength of the competitive interaction exerted on a target tree by a given neighbor. By summing up the virtual competitive pressure of all neighbors in a single competitive pressure vector, we were able to predict the direction of crown asymmetry of the focal tree with an accuracy of 96° on the full circle (360°). The competitive pressure model was equally applicable to beech, ash and hornbeam trees and may generate valuable insight into competitive interactions among tree crowns in mixed stands, provided that sufficiently precise data on the shape and position of the tree crowns is available. Multiple-aspect laser-scanning proved to be an accurate and practicable approach for analyzing the complex 3-dimensional shape of the tree crowns, needed to quantify the plasticity of growth processes in the canopy. We conclude that the laser-based analysis of crown plasticity offers the opportunity to achieve a better understanding of the dynamics of canopy space exploration and also may produce valuable advice for the silvicultural management of mixed stands.

Tunable laser-based design and analysis for fractional lambda switches

Fractional lambda switching (FlambdaS) is a novel approach for traffic management over all-optical networks with sub-wavelength provisioning capability. The unique characteristic of FlambdaS is the utilization of UTC (coordinated universal time) for switching with minimum or no buffers. Several central research issues are still open in FlambdaS and need to be formally defined and analyzed. In this paper, we introduce three novel switch designs that are based on the use of tunable lasers (which can be replaced in the future with wavelength converters). First, the paper presents analytical results of scheduling feasibility, which measures the total number of possible different schedules for each switch design. Then it is shown that the architecture with the highest scheduling feasibility is strictly non blocking in the space domain. Next, the paper provides a closed form analysis of the blocking probability in the time domain, which is applicable for any strictly non-space blocking switch, using combinatorics. In addition, the paper provides measures of the switching hardware complexity, which, for the strictly non-blocking architecture, has the same switching complexity as Clos interconnection network, i.e., O(N'radic(N')) where N' is the number of optical channels.

Evaluation of a point-of-care hematology analyzer for use in dogs and cats receiving chemotherapeutic treatment

To compare WBC, neutrophil, and platelet counts and Hct values obtained with a point-of-care hematology analyzer with values obtained by a reference method for dogs and cats receiving chemotherapy. Cross-sectional study. 105 dogs and 25 cats undergoing chemotherapy. Blood samples were analyzed with a point-of-care hematology analyzer and with an impedance- and laser-based analyzer with manual differential WBC counts. Results for WBC, neutrophil, and platelet counts and Hct were compared. Sensitivity and specificity of the point-of-care analyzer to detect leukopenia, neutropenia, and anemia were calculated. 554 canine and 96 feline blood samples were evaluated. Correlation coefficients for dogs and cats, respectively, were 0.92 and 0.95 for total WBC count, 0.91 and 0.88 for neutrophil count, 0.95 and 0.92 for Hct, and 0.93 and 0.71 for platelet count. Sensitivity and specificity, respectively, of the point-of-care analyzer to detect leukopenia were 100% and 75% for dogs and 100% and 68% for cats; to detect neutropenia were 80% and 97% for dogs and 100% and 80% for cats; to detect anemia were 100% and 80% for dogs and 100% and 66% for cats; and to detect thrombocytopenia were 86% and 95% for dogs and 50% and 87% for cats. The point-of-care analyzer was reliable for monitoring CBCs of dogs and cats receiving chemotherapy. It had good to excellent correlation for WBC and neutrophil counts and Hct and accurately detected leukopenia, neutropenia, and anemia. Sensitivity of the analyzer for detecting thrombocytopenia was lower but acceptable.

Implementing Laser-Based Failure Analysis Methodologies Using Test Vehicles

Several test vehicles were designed in order to validate laser-based failure analysis and process validation techniques. Two vehicles concern defect localization in integrated circuits (ICs); the third one is designed for single event upset sensitivity study in digital ICs.

Liquid steel analysis with laser-induced breakdown spectrometry in the vacuum ultraviolet

Laser-induced breakdown spectrometry (LIBS) with multiple pulse excitation has been applied for the multielemental analysis of liquid steel. The laser beam and the measuring radiation are guided inside a moveable lance to gain access to the melt surface from the top. Low-alloy steel grades were investigated with a focus on the light elements phosphorus, sulfur, and carbon by use of emission wavelengths in the vacuum ultraviolet. Calibration curves were determined for the elements carbon, phosphorus, sulfur, nickel, and chromium in steel melts of 100 kg. The estimated limits of detection for the light elements phosphorus, sulfur, and carbon are below 21 microg/g for direct analysis of liquid steel with LIBS. The results demonstrate the potential of the laser-based analysis to fulfill the requirements for a process integrated on-line analysis in the secondary metallurgy of steel works.

Laser analysis of the 13C/12C isotope ratio in CO2 in exhaled air

Tunable diode lasers (TDLs) are applied to the diagnostics of gastroenterological diseases using respiratory tests and preparations enriched with the stable 13C isotope. This method of the analysis of the 13C/12C isotope ratio in CO2 in exhaled air is based on the selective measurement of the resonance absorption at the vibrational — rotational structure of 12CO2 and 13CO2. The CO2 transmission spectra in the region of 4.35 μm were measured with a PbEuSe double-heterostructure TDL. The accuracy of carbon isotope ratio measurements in CO2 of exhaled air performed with the TDL was ~0.5%. The data of clinical tests of the developed laser-based analyser are presented.

Determination of the octane number of a fuel by the IR spectroscopy method

The near-IR spectroscopy method of control of the octane number (o.n.) of a fuel is studied. An analysis is made of a device developed as an alternative of a measuring system based on a nonselective IR radiation source and of an analyzer based on a laser semiconductor diode. It is shown that the use of the methods of multicomponent regression analysis of spectral data allows measurement of the octane number with an accuracy of S ∼ 0.17 octane number units. The characteristics of the semiconductor laser-based analyzer are investigated and the parameters of radiators are discussed that provide the required sensitivity of the measuring system (up to 10−4 with respect to optical absorption) in controlling the octane number of a fucl.

Using a Road Surface Analyzer to Explain Noise Characteristics of Portland Cement Concrete Pavement Surface Texture

Uniformly spaced, transverse-tined portland cement concrete (PCC) pavements have been in extensive use in the United States since the early 1970s. Recent research by the Wisconsin Department of Transportation (WisDOT) and FHWA has led to an interim guideline for randomization of the tining pattern, with spacings varying from 10 to 40 mm and 50 percent of the spacings at or below 25 mm. At least five states have experimented with this random pattern. A six-state research study, funded by WisDOT and FHWA, was completed in 2000 by Marquette University and the HNTB Corporation. This study investigated 57 different PCC pavement textures, including a wide range of transverse and longitudinal tining patterns. One goal was to explain noise differences within and between various textures as well as to document noise and texture differences. The laser-based road surface analyzer (ROSAN), developed cooperatively by the Turner Fairbanks Research Center and private industry, was utilized for surface textural measurements. Before the advent of laser-based texture measurement devices, large studies of this type would have relied on manual volumetric (sand patch) measurements to quantify surface textural differences, making virtually impossible the determination of reasons for differences in noise characteristics of various textures. The use of ROSAN is described, tools developed to analyze textural variations and noise characteristics of tined pavement surfaces are presented, and correlations between ROSAN outputs and other variables, including noise level and sand patch measurements, are provided. Examples of simple and more subtle causes of noise discrepancies on random transverse tined PCC pavements are presented by use of ROSAN outputs. A great variation in surface texture, including tine spacing, width, and depth, was found among different PCC pavement sections constructed to identical tining specifications. Significant variations were also noted within any given test section in all states. A low correlation between ROSAN estimated texture depth and noise was observed. A more significant correlation between depth and width of tining was observed with use of ROSAN outputs. Recommendations include the need for quality control of tine depth, the need for a wet pavement accident study to determine tining depth requirements, and the development of an improved measurement device for measuring longitudinally tined PCC pavements.

Performance of Sonication and Microfluidization for Liquid–Liquid Emulsification

The purpose of this research was to evaluate and compare liquid–liquid emulsions (water-in-oil and oil-in-water) prepared using sonication and microfluidization. liquid–liquid emulsions were characterized on the basis of emulsion droplet size determined using a laser-based particle size analyzer. An ultrasonic-driven benchtop sonicator and an air-driven microfluidizer were used for emulsification. Sonication generated emulsions through ultrasound-driven mechanical vibrations, which caused cavitation. The force associated with implosion of vapor bubbles caused emulsion size reduction and the flow of the bubbles resulted in mixing. An increase in viscosity of the dispersion phase improved the sonicator's emulsification capability, but an increase in the viscosity of the dispersed phase decreased the sonicator's emulsification capability. Although sonication might be comparable to homogenization in terms of emulsification efficiency, homogenization was relatively more effective in emulsifying more viscous solutions. Microfluidization, which used a high pressure to force the fluid into microchannels of a special configuration and initiated emulsification via a combined mechanism of cavitation, shear, and impact, exhibited excellent emulsification efficiency. Of the three methodologies, sonication generated more heat and might be less suitable for emulsion systems involving heat-sensitive materials. Homogenization is in general a more effective liquid–liquid emulsification method. The results derived from this study can serve as a basis for the evaluation of large-scale liquid–liquid emulsification in the microencapsulation process.

Absolute and/or relative detection limits in laser-based analysis: the end justifies the means.

The absolute limit of detection usually expresses the minimum amount of analyte detectable, while the relative limit of detection refers to the minimum concentration of analyte detectable. These concepts and their differences are obviously familiar to all analytical spectroscopists. Nevertheless, the two definitions are used liberally in the literature. For example, it is not uncommon to refer to exceptional sub-femtograms detection limits for a technique used to analyse ultratrace levels of an element in water and to a modest part per million detection limit of another technique used to characterise the microdistribution of an element in a sample mass of about one microgram. In this paper, an attempt is made to point out that the terms "ultratrace analysis" and "microanalysis" must refer to two conceptually different approaches and that there are cases in which one definition is more appropriate than the other. It is argued that, while there is no objection in reporting both detection limits when a single technique is evaluated, one has to be careful in choosing the most appropriate definition when different analytical techniques are compared.

Thrombin and Parathyroid Hormone Mobilize Intracellular Calcium in Rat Osteosarcoma Cells by Distinct Pathways*

The mechanisms by which PTH and thrombin mobilize intracellular Ca2+ (Cai2+) were examined in UMR 106-H5 rat osteosarcoma cells. Bovine PTH-(1-34) (24 pM to 240 nM) produced a dose-dependent increase in Cai2+ (EC50, 3 nM), which returned to baseline within 75 sec. Human alpha-thrombin produced an increase in Cai2+ (ECmax, 10 U/ml) which was similar to that of PTH with respect to both magnitude and time course. Chelation of extracellular calcium with 5.0 mM EGTA did not alter the Cai2+ response to either PTH or thrombin. When added together at maximally effective concentrations, PTH and thrombin produced additive effects on Cai2+ in the presence and absence of EGTA. The additive effects of PTH and thrombin on Cai2+ were confirmed at the single cell level, using laser-based image analysis. Bradykinin (1 microM) produced a significant increase in Cai2+ in UMR 106-H5 cells which was of lesser magnitude than the peak 2- to 3-fold increase elicited by PTH or thrombin. Preexposure of cells to 10 U/ml thrombin for 2 min abolished the Cai2+ response to bradykinin, whereas preexposure to 240 nM PTH had no effect on the Cai2+ response to bradykinin. Thrombin elicited a rapid increase in the accumulation of 3H-labeled inositol phosphates (IP2 and IP3) in UMR 106-H5 cells, with increases in [3H]1,4,5-IP3 detectable as early as 15 sec after the addition of thrombin. Bradykinin increased [3H]IP production to a lesser extent than thrombin, whereas PTH neither increased [3H]IP accumulation nor potentiated the [3H]IP response to thrombin. The results suggest that thrombin and bradykinin mobilize Cai2+ from a shared IP3-responsive calcium pool, whereas PTH may use signals in addition to 1,4,5-IP3 to mobilize calcium from a distinct cellular calcium pool. Alternatively, specific calcium compartmentalization exists, and there is differential coupling of these agonists to the 1,4,5-IP3/Cai2+ pathway.

Comparison of the hematologic effects of 2-butoxyethanol using two types of hematology analyzers

Earlier reports from this laboratory indicated that 2-butoxyethanol (BE) causes acute hemolytic anemia in rats as evidenced by a time- and dose-dependent decrease in the number of red blood cells, in hemoglobin concentrations, and in hematocrits (HCT). Subsequent studies showed that treatment with BE causes an early increase in HCT and mean cell volume (MCV). Since this effect went undetected in our early work and resulted in the publication of inaccurate information, present studies were designed to reinvestigate the hematologic effects of BE using the laser-based hematology analyzer which was used in the early studies and an impedance-based hematology analyzer, simultaneously. Packed cell volumes (PCV; spun HCT) were also performed on all blood samples. Male F344 rats were treated with 0, 125, 250, or 500 mg BE/kg (po) and blood was collected from the retro-orbital venous plexus at 1, 2, 4, 8, and 24 hr after dosing. Hematology profiles of BE-treated rats obtained from the impedance-based analyzer showed an early dose- and time-dependent increase in HCTs and MCVs. In contrast, analysis of the same blood samples using the laser-based analyzer showed a dose- and time-dependent decrease in HCTs with little or no change in MCVs. Changes observed in PCVs were consistent with results obtained from the impedance-based analyzer. Therefore, under the experimental conditions of this and previous studies, the laser-based analyzer was unable to detect early increases in HCTs and MCVs in rats treated with BE. Finally, these data explain the different principles utilized to measure cell size by both instruments as they relate to the hematologic effects of BE. Moreover, present data show that BE-induced hemolysis of erythrocytes is preceded by a quantitatively unique and massive swelling suggesting the erythrocyte membrane as the target.

Extended leukocyte parameters for hematology analyzers.

Newly introduced, extended leukocyte parameters on laser-based hematology analyzers permit normal samples to be readily identified allowing these samples to be excluded from manual analysis. This enables more hematology laboratory resources to be focused on abnormal specimens. A new reagent that lyses erythrocytes while leaving the optical properties of the leukocytes unaltered is used. A special optical bench measures both narrow-angle forward light scatter (an indicator of cell size) and wide-angle light scatter (an indicator of cell granularity). The two scatter measurements are combined to produce a histogram in which lymphocytes, monocytes, and granulocytes are clearly delineated. A microprocessor detects the separation between histogram peaks, sets the proper thresholds, produces the three-part count, and indicates abnormal samples on the basis of histogram peak position, shape, and resolution. In a clinical study correlations between instrument counts and manual leukocyte differentials were very good. The potential for reducing the number of manual differentials of normal samples is significant.