Spectrometry Data Research Articles

The Impact of Fluid Mechanical Stress on Saccharomyces Cerevisiae Cells During Continuous Cultivation in an Agitated, Aerated Bioreactor; its Implication for Mixing in the Brewing Process and Aerobic Fermentations

The introduction of mechanical agitation or re-circulation of CO 2 from the headspace to facilitate the natural CO 2 -driven mixing in anaerobic brewing fermentations has the potential to cause damage to yeast cells through increased hydrodynamic stress. In addition, such damage has been reported in aerobic yeast fermentations. Here, a reproducible, duplicate series of aerobic, carbon-limited, continuous culture yeast fermentations have been carried out up to approximately 340 h. In the first series, mean specific energy dissipation rates, e ¯ T from ∼4.5 × 10 –2 to ∼6.0 W kg −1 were used, the former mimicking for approximately 20 h the maximum level found in anaerobic fermentations at the large scale and the latter a higher value than that usually found in aerobic fermentations. In the second, e ¯ T was held at ∼4.5 x 10 −2 W kg −1 and two aeration rates (1 and 3 vvm) were used. Both values are very high for brewing, even if headspace CO 2 recirculation is used. The latter value is also high for aerobic fermentations. In all cases, the dissolved oxygen level was held constant by gas blending at 40% of saturation. At e ¯ T > ∼4.5 W kg −1 , a transient effect on the cells as measured by multi-parameter flow cytometry was found, but all other measured parameters, including mass spectrometry and classical microbiological data, showed that, statistically, there was no effect on cellular morphology or physiology. For all other conditions of agitation and aeration, all measured parameters remained constant. This study indicates that the potentially deleterious effects of agitation or CO 2 gas recirculation can be largely discounted with respect to brewing fermentations and for more intense aerobic fermentations up to ∼6 W kg −1 and 3 vvm.

Microstructure and microchemistry of silicon particles formed during electrical-discharge machining

The structure and morphology of particles representing the byproduct of electrical-discharge machining (EDM) were analyzed using transmission electron microscopy (TEM). The EDM process involved high-efficiency and high-accuracy fine boring of a single-crystal silicon ingot by high-frequency electrical spark discharges. As the silver electrode advanced, spark-discharge-melted or vaporized small particles of the silicon workpiece were produced and the particles were flushed away and collected in deionized water. Standard TEM and analytical electron microscopy (AEM) observations were carried out. Bright-field (BF) images, diffraction, and energy-dispersive X-ray spectrometry (EDXS) data were obtained to completely characterize the EDM particles. BF images indicated the presence of large silicon particles decorated by smaller silver particles originating from the electrode as the byproducts of the EDM processing. Analysis of the particle-size distribution resulted in an average silicon particle size of about 500 nm decorated by smaller silver particles of an average size of about 65 nm. EDXS spectra depicted individual silicon and silver particles with characteristic peaks that identify the elements present. Selected-area electron diffraction (SAED) pattern confirmed the presence of crystalline silicon. Finally, a set of SAED patterns, EDXS profiles, and TEM images is included that fully describe the particles' chemistry, structure, and morphology, respectively.

Novel synthesis of cyclic methylvinylsiloxanes by the reaction of methylvinyl diethoxysilane with phosphorous pentachloride

We report a novel synthesis of the cyclic oligomers [(H2CCH)(CH3)SiO]n obtained by the reaction between phosphorous pentachloride and methylvinyl diethoxysilane. According to gas chromatography/mass spectrometry data, the reaction product consisted of a mixture of cyclic oligomers in which the most important fractions were composed of cycles with n = 5, 6, or 7. The reaction product was also characterized by Fourier transform infrared and 1H and 13C NMR spectroscopy. Experimental results suggested a new kind of reaction between the phosphorous pentachloride and terminal olefins directly bonded to silicon, which was probably associated with sterical effects favoring COSi bond cleavage of ethoxy groups instead of the conventional addition of phosphorous pentachloride to olefinic linkages. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3182–3189, 2002

Fragmentation Mechanism of Trans‐α‐Aryl‐β‐enamino Esters

AbstractElectron impact‐induced fragmentation mechanisms of trans‐α‐aryl‐β‐enamino esters were investigated using mass‐analyzed ion kinetic energy (MIKE) spectrometry and high resolution accurate mass data. It was found that the main characteristic fragmentations of compounds studied were: an odd electron ion M+ ‐ EtOH was formed by losing a neutral molecule of ethanol; and the skeletal rearrangements took place; and the ring opening reaction happened after losing a carbon monoxide; and the typical McLafferty rearrangement underwent in ester group. The cyclization reaction caused by losing neutral molecule of TsNH2 due to the ortho‐effects of substituted group of aromatic ring was also observed.

New algorithms for processing and peak detection in liquid chromatography/mass spectrometry data.

Two new algorithms for automated processing of liquid chromatography/mass spectrometry (LC/MS) data are presented. These algorithms were developed from an analysis of the noise and artifact distribution in such data. The noise distribution was analyzed by preparing histograms of the signal intensity in LC/MS data. These histograms are well fit by a sum of two normal distributions in the log scale. One new algorithm, median filtering, provides increased performance compared to averaging adjacent scans in removing noise that is not normally distributed in the linear scale. Another new algorithm, vectorized peak detection, provides increased robustness with respect to variation in the noise and artifact distribution compared to methods based on determining an intensity threshold for the entire dataset. Vectorized peak detection also permits the incorporation of existing algorithms for peak detection in ion chromatograms and/or mass spectra. The application of these methods to LC/MS spectra of complex biological samples is described.

Development and validation of a competitive immunoassay for urinary S-phenylmercapturic acid and its application in benzene biological monitoring

An immunoassay that quantifies urinary S-phenylmercapturic acid (PMA), a benzene-specific biomarker, has been developed and its potential usefulness as a screening tool for monitoring occupational exposure to benzene has been demonstrated. Analytical reliability has been confirmed by correlation of results with gas chromatography-mass spectrometry (GC/MS) data (R = 0.92). The assay has been configured as a competitive enzyme-linked immunosorbent assay (ELISA) to facilitate rapid throughput of samples. The ELISA has a working range of 40-1200 nmol l-1 urinary PMA and appears to be unaffected by the presence of structurally related urinary metabolites. Background levels of 0-1.9μmol PMA/mol creatinine (mean 0.9 μmol mol-1, n = 32) were measured in non-smoking control subjects. Recent exposures to benzene (8 h time-weighted averages-TWA), during diverse industrial processes, over the range 0-4.8ppm were identified by application of the assay in biological monitoring programmes.

Cation distribution and magnetic properties of manganese ferrite powder prepared by coprecipitation from MnO2 and FeSO4·7H2O

Based on X-ray diffraction and Mössbauer spectrometry data, SEM and ferromagnetic measurements, the authors present some results concerning the microstructure and magnetic properties of manganese ferrite powder prepared by coprecipitation from MnO2 and FeSO4·7H2O as raw materials.

OARS - A New System for Mapping Surface Mineralogy Simultaneously with Airborne Geophysics

The Operational Airborne Research Spectrometer (OARS) is a novel hyperspectral profiling reflectance spectrometer developed by the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and Fugro Airborne Surveys (FAS) to examine alternative means to collect and deliver exploration data, based on the principles of reflectance spectroscopy. OARS is a component of CSIRO's "Airborne Mineralogy" concept.OARS can be integrated with other airborne geophysical instruments that principally collect magnetic, gamma-ray spectrometry and digital elevation data, and can be flown simultaneously on exactly the same flight lines. OARS will measure ground reflectance spectra from contiguous 8-m pixels from an altitude of 80 m.After data processing, interpolated images of relative mineral abundance can be reconstructed using differential GPS (DGPS) positioning data to produce a variety of mineralogical maps.The OARS system consists of a downward and an upwardlooking spectrometer. Each spectrometer covers 190 spectral channels in the visible to short-wave infrared range, with an average spectral resolution of 12 nm. This wavelength range allows OARS to map most species of phyllosilicates, clays, sulphates, carbonates and iron oxides, that occur in alteration zones, regolith and host rocks. Green and dry vegetation can also be identified. A CCD camera (Charge Coupled Device – Silicon Array) allows monitoring of the flight path while flight attitude sensors and DGPS are used for geo-location.The instrument was first tested in late 1998. Subsequent test surveys in early 1999, over a more challenging geological area in NW Australia, verified its ability to deliver new mineralogical data and its capability as part of an integrated system incorporating magnetic and gamma-ray spectrometry surveying. The resulting case study shows that this line profiling spectrometer can deliver useful interpolated mineral maps with potential synergistic benefits from co-registered magnetic and gamma ray images.

Quantitative Secondary Ion Mass Spectrometry (SIMS) of III-V Materials

AbstractSecondary ion mass spectrometry (SIMS) provides direct methods to characterize the chemical composition of III-V materials at major, minor and trace level concentrations as a function of layer depth. SIMS employs keV primary ions to sputter the surface and sensitive mass spectrometry techniques to mass analyze and detect sputtered secondary ions which are characteristic of the sample composition. In-depth compositional analysis of these materials by SIMS relies on a number of its unique features including: (1) keV primary ion sputtering yielding nanometer depth resolutions, (2) the use of MCs+ detection techniques for quantifying major and minor constituents, and (3) ion implant standards for quantifying trace constituents like dopants and impurities. Nanometer depth resolution in SIMS sputtering provides accurate detection of diffusion of dopants, impurities and major constituents. MCs+ refers to the detection of “molecular” ions of an element (M) and the Cs+ primary beam. MCs+ minimizes SIMS matrix effects in analysis for major and minor constituents, thus providing good quantification. This paper presents a SIMS study of AlxGa1−xAs structures with three different x values. MCs+ (M=Al or Ga) data are presented for the accurate determination of major and minor components. Rutherford backscattering spectrometry (RBS) and x-ray diffraction (XRD) data were crosscorrelated with the MCs+ results. Three specimens with different x values were ion implanted with H, C, O, Mg, Si, Zn and Se to study quantification of trace levels. SIMS data acquired on a double focusing instrument (CAMECA IMS-4f) and a quadrupole instrument (PHI ADEPT 1010) are also compared. Lastly, we discuss our efforts to improve the analysis precision for pand n-type dopants in AlGaAs which currently is ± 3% (1 sigma).

Identification and reactivity of the major metabolite (ß-1-glucuronide) of the anti-tumour agent 5,6-dimethylxanthenone-4-acetic acid (DMXAA) in humans

1. The novel anti-tumour agent 5,6-dimethylxanthenone-4-acetic acid (DMXAA) is extensively metabolized by glucuronidation and 6-methylhydroxylation, resulting in DMXAA acyl glucuronide (DMXAA-G) and 6-hydroxymethyl-5-methylxanthenone-4-acetic acid (6-OH-MXAA). 2. The major human urinary metabolite of DMXAA was isolated and purified by a solid-phase extraction (SPE) method. The isolated metabolite was hydrolysed to free DMXAA by strong base, and by β-glucuronidase. Liquid chromatography-mass spectrometry (LC-MS) and spectral data indicated the presence of a molecular ion [M + 1]+ at m/z 459, which was consistent with the molecular weight of protonated DMXAA-G. 3. The glucuronide was unstable in buffer at physiological pH, plasma and blood with species variability in half-life. Hydrolysis and intramolecular migration were major degradation pathways. 4. In vitro and in vivo formation of DMXAA-protein adducts was observed. The formation of DMXAA-protein adducts in cancer patients receiving DMXAA was significantly correlated with plasma DMXAA-G concentration and maximum plasma DMXAA concentration. 5. At least five metabolites of DMXAA were observed in patient urine, with up to 60% of the total dose excreted as DMXAA-G, 5.5% as 6-OH-MXAA and 4.5% as the glucuronide of 6-OH-MXAA. 6. These data suggest that the major metabolite in patients’ urine is DMXAA β-1- glucuronide, which may undergo hydrolysis, molecular rearrangement and covalent binding to plasma protein. The reactive properties of DMXAA-G may have important implications for the pharmacokinetics, pharmacodynamics and toxicity of DMXAA.

Influences of the basin brines on extractable bitumen of Kupferschiefer from southwestern Poland

A study of the influences of the basin brines on hydrocarbon generation of the Kupferschiefer in southwestern Poland has been carried out. The samples from the Konrad and Polkowice mines were analyzed by organic geochemical, microscopic and FTIR methods. The results indicate that organic matter of Kupferschiefer tends to decrease with the ascending, oxidizing brines. In the Konrad profile, the Kupferschiefer was strongly oxidized. The extract yields were depleted up to 50mg Ext/g Corg. Gas chromatography (GC) and gas chromatography-mass spectrometry (GC/MS) data indicate that the depletion occurred predominantly in saturated hydrocarbon compounds. The identified n-alkanes in sample KD1 were depleted at least to 5000 μg/g Corg. The aromatic compounds show a different trend of variation. The concentrations of phenanthrene + alkylphenanthrenes (Ph-PAH) and naphthalene + alkylnaphthalenes (Na-PAH) show a decrease, whereas sulfur polyaromatic hydrocarbons (S-PAH) and oxygen polyaromatic hydrocarbons (O-PAH) show an increase under the influences of oxidizing brines. In the Polkowice profile, organic matter under the influences of oxidizing fluids shows a similar trend of variation as in the Konrad mine. Analyses of polar compounds shed light on the oxidation processes at the molecule level. The dominant products of oxidation are aliphatic acid, alcohol and ester. FTIR results indicate that the oxidation of organic matter led to a decrease in aliphatic CH3 and an increase in C-O, C=O bands.

Application of partial least squares calibration for multicomponents determination by flow injection-solid phase spectrophotometry

This article reports the use of solid phase spectrophotometry associated with flow injection technique for simultaneous determination of zinc and nickel with 1-(2-thiazolylazo)-2-naphthol (TAN) immobilized on a C18 bonded silica support in the concentration range from 0.30 to 1.0 μg mL −1 of both ions. The multicomponent analysis was implemented using the absorbance signals in different intervals of time in a flow injection analysis peak for each sample solution inserted into the analytical path. A partial least squares (PLS) algorithm for model construction was developed in QuickBasic 4.5 as a subrotine in order to assemble it in a data acquisition program, permitting the concentration estimation in real time. The proposed method was successfully applied to nickel and zinc determination in synthetic mixtures with analytical throughput of 43 samples per hour. The results obtained with the proposed method were compared with Inductively Coupled Plasma Atomic E Mission Spectrometry (ICP-AES) data, and the results agreed with 95% confidence level. © 2000 John Wiley & Sons, Inc. Lab Robotics and Automation 12:305–311, 2000

An integrated method for spectrum extraction and compound identification from gas chromatography/mass spectrometry data

A method is presented for extracting individual component spectra from gas chromatography/mass spectrometry (GC/MS) data files and then using these spectra to identify target compounds by matching spectra in a reference library. It extends a published “model peak” approach which uses selected ion chromatograms as models for component shape. On the basis of this shape, individual mass spectral peak abundance profiles are extracted to produce a “purified” spectrum. In the present work, ion-counting noise is explicitly treated and a number of characteristic features of GC/MS data are taken into account. This allows spectrum extraction to be reliably performed down to very low signal levels and for overlapping components. A spectrum match factor for compound identification is developed that incorporates a number of new corrections, some of which employ information derived from chromatographic behavior. Test results suggest that the ability of this system to identify compounds is comparable to that of conventional analysis.

Effect of polymer architecture on self-diffusion of LC polymers

Two LC side-group poly(methacrylates) were synthesized, and their melt dynamics were compared with each other and a third, main-chain side-group combined LC polymer. A new route was developed for the synthesis of the poly(methacrylate) polymers which readily converts relatively inexpensive perdeuteromethyl methacrylate to other methacrylate monomers. Self-diffusion data was obtained through the use of forward recoil spectrometry, while modulus and viscosity data were measured using rotational rheometers in oscillatory shear. Diffusion coefficients and complex viscosity were compared to previous experiments on liquid crystal polymers of similar architecture to determine the effect of side-group interdigitation and chain packing on center of mass movement. The decyl terminated LC side-group polymer possessed an interdigitated smectic phase and a sharp discontinuity in the self-diffusion behavior at the clearing transition. In contrast, the self-diffusion behavior of the methyl terminated LC side-group polymer, which possessed head-to-head side-group packing, was seemingly unaffected by the smectic-nematic and nematic-isotropic phase transitions. The self-diffusion coefficients of both polymers were relatively insensitive to the apparent glass transition. The presence of moderately fast sub-T g chain motion was supported by rheological measurements that provided further evidence of considerable molecular motion below T g . The complex phase behavior of the combined main-chain side-group polymer heavily influenced both the self-diffusion and rheological behavior. Differences between the self-diffusion and viscosity data of the main-chain side-group polymer could be interpreted in terms of the defect structure.

Effects of Thickness and Oxygen Content on Thermomechanical Behavior of Thin Cu Films Passivated with Ain

AbstractThe thermomechanical behavior of a Cu thin film can be dramatically influenced (“oxygen effect”) by exposing the film to a small amount of air or oxygen prior to passivation. Film exposure is accomplished by breaking vacuum at some point prior to passivation. When the top surface is exposed immediately before passivation, the oxygen effect is produced when the passivation material is Si3N4, but no effect is seen with AIN passivations. However, the effect is seen in AIN passivated films when the Cu film surface is exposed to air or O2 and additional Cu is deposited before passivation. This suggests that conditions at the film/passivation interface are an important factor in this anomalous plasticity effect. We have investigated the effects of film thickness and oxygen concentration on these behaviors by preparing films with different thicknesses and oxygen contents for thermomechanical analysis. The thermomechanical behavior is correlated with secondary ion mass spectrometry (SIMS) data that shows oxygen concentration vs. film depth. The presence of the “oxygen effect” in thermomechanical behavior is found to be correlated with an increased oxygen concentration near the film/passivation and film/barrier interfaces.

New software tools for visualization of analytical data

Efforts towards using advanced computer graphics for improved visualization of three-dimensional (3-D) secondary ion mass spectrometry (SIMS) data are described. The application of the Visualization Toolkit (vtk), a freely available C++ class library for 3-D graphics and visualization for both PC and Unix systems, is demonstrated. Various available algorithms are used to analyze and visualize features otherwise hidden within data. A selection of examples is presented to demonstrate the capabilities of data visualization.

Development of Immunoassays for Type II Synthetic Pyrethroids. 2. Assay Specificity and Application to Water, Soil, and Grain.

Cross-reactions of a panel of immunoassays developed for type II (alpha-cyano-) synthetic pyrethroids were evaluated with type I and II compounds. Cross-reactions of both groups were affected by alkali treatment. The treatment typically increased sensitivities of type II compounds, and decreased cross-reactions of type I compounds. After isomerization, each of the 12 combinations studied provided more sensitive detection of deltamethrin than the other compounds, even in the case of antisera and enzyme conjugates based on cypermethrin, cyhalothrin, or their fragments. Several immunoassays were selective for deltamethrin. Assays with the broadest specificities detected type I and II compounds with IC(50) values of 20-400 µg/L. None of the assays detected compounds lacking a cyclopropane ring (fenvalerate, fluvalinate). Spike and recovery studies for deltamethrin in water, soil, and wheat grain indicated that the selected immunoassays quantified it with high precision and good recoveries. Good correlations between immunoassay and gas chromatography/mass spectrometry data were also obtained for incurred residues of deltamethrin and bifenthrin extracts of water and soil samples.

SYNTHESIS OF α-THIOPHENE OLIGOMERS VIA ORGANOTIN COMPOUNDS

A versatile synthetic route involving the use of organotin compounds has been applied for the preparation of functionalized oligothiophenes. Thus, substituted α-bithiophenes have been synthesized via the coupling reaction of 2-bromothiophenes with 2-trimethylstannylthiophene. The latter reagent couples with 2,5-dibromothiophenes to give the α-terthiophenes which are also accessible through the reaction of 5-trimethylstannyl-α-bithiophene with 2-bromothiophenes. 2,5-Bis(trimethylstannyl) thiophene and 5,5′-bis(trimethylstannyl)-α-bithiophene react with 2-bromothiophenes to give α-terthiophenes and α-quaterthiophenes, respectively. α-Quaterthiophene is also produced via the reaction of 5-trimethylstannylthiophene with 5,5′- dibromo-α-bithiophene. The coupling reaction of 5-tnmethylstannyl-α-bithiophene with 2.5-dibromothiophene affords the α-quinquethiophene. The structures of the new compounds were confirmed by elemental analysis, Mass spectrometry, 1H- and 13CNMR spectral data.

A study of the solid state `amorphization' reaction in by diffraction and Mössbauer spectrometry

The solid state `amorphization' reaction produced by the mechanical alloying (MA) of samples of the eutectic alloy has been studied using x-ray and neutron diffraction and Mössbauer spectrometry. The consumption of the parent elements as a function of time of MA treatment has been derived from the reduction in intensity of their Bragg peaks in the diffraction patterns. The change of volume fraction of the parent -iron phase with increasing time of MA treatment has been determined from the reduction in intensity of the sextet in the Mössbauer spectra. The diffraction data and spectrometry data are in good overall agreement and both show that the reaction is very rapid in this eutectic alloy and that the parent iron and tantalum powders are transformed into an amorphous phase after only 6 h MA treatment in a conventional Spex 8000 high-energy ball mill. In detail, the consumptions of the parent elements derived from the two kinds of measurement are slightly different. This is possibly because the diffraction data represent an average over the whole sample while the Mössbauer spectrometry data are site specific.

Homozinniol, a New Phytotoxic Metabolite from Alternaria solani

A bioassay-guided fractionation of the phytotoxic crude extract of Alternaria solani resulted in the isolation of two phytotoxic metabolites identified as zinniol (1) and a new polyketide: homozinniol (2). A third metabolite, 6-[(3‘,3‘-dimethylallyl)oxy]-4-methoxy-5-methylphthalide (3) was also isolated and identified. Structural assignment of the metabolites was based primarily on the analysis of their mass spectrometry and 1H NMR spectroscopy data. Keywords: Alternaria solani; Solanum tuberosum; Lycopersicon esculentum; phytotoxin; zinniol; homozinniol; polyketide; phthalide