bluuebunny/crossref_metadata_2025 huggingface dataset:
Intermediate States in the Melting Process of Low Molecular Weight Poly(Ethylene Oxide)
Authors: Zhou Hu , Feng Jiachun , Wu Peiyi
Published: October 2010

The melting behavior of low molecular weight poly(ethylene oxide) (PEO) fractions has been studied via generalized two-dimensional infrared (2D-IR) correlation spectroscopy and a new stochastic-pulse-based temperature modulation differential scanning calorimetry (DSC) technique (TOPEM®). 2D-IR correlation analysis of the melting of PEO shows that vs(CH2) and γa(CH2) vary prior to vs(COC). Moreover, the TOPEM® experiments show that reversible melting and crystallization is occurring during the melting of PEO. These suggest that the melting of PEO is possibly a process passing over intermediate states. Based on our results, a model of the melting process of PEO lamellae is presented: the intermediate states containing the distorted helical conformation are formed first at the front of the lamellae during the melting process.
An Improved Fe—Ni Sulfide Fire Assay Method for Determination of Re, Platinum Group Elements, and Os Isotopic Ratios by Inductively Coupled Plasma- and Negative Thermal Ionization—Mass Spectrometry
Authors: Sun Yali , Chu Zhuyin , Sun Min , Xia Xiaoping
Published: October 2010

An improved Fe–Ni sulfide fire assay method has been developed for determination of Re, the platinum group elements (PGE), and Os isotopic ratios using inductively coupled plasma–mass spectrometry (ICP-MS) and negative thermal ionization–mass spectrometry (NTI-MS). Recovery of Re using the neoclassical NiS fire assay technique is very low, but recoveries of up to 75% can be achieved by using Fe–Ni sulfide as a collector and Na2B4O7 as a flux. Using isotope dilution for determination of Re, a number of standard reference materials were analyzed for PGE and Re, and the results are consistent with their certified values. Multiple analyses of the reference standard GBW 07290 produced precisions ranging from 2.2% for Os to 5.9% for Ir. The detection limits are 2 pg g−1 for Ru, 1.5 pg g−1 for Rh, 25 pg g−1 for Pd, 23 pg g−1 for Re, 0.7 pg g−1 for Os, 1 pg g−1 for Ir, and 6 pg g−1 for Pt. The low procedural blank of Os (1.3 pg g−1) makes the Fe–Ni sulfide fire assay suitable for analysis of Os isotopic compositions. Using NTI-MS, the 187Os/188Os ratios were measured for WPR-1 and they are consistent with literature values.
An Iterative Algorithm for Background Removal in Spectroscopy by Wavelet Transforms
Authors: Galloway C. M. , Ru E. C. Le , Etchegoin P. G.
Published: October 2010

Wavelet transforms are an extremely powerful tool when it comes to processing signals that have very “low frequency” components or non-periodic events. Our particular interest here is in the ability of wavelet transforms to remove backgrounds of spectroscopic signals. We will discuss the case of surface-enhanced Raman spectroscopy (SERS) for illustration, but the situation it depicts is widespread throughout a myriad of different types of spectroscopies (IR, NMR, etc.). We outline a purpose-built algorithm that we have developed to perform an iterative wavelet transform. In this algorithm, the effect of the signal peaks above the background is reduced after each iteration until the fit converges close to the real background. Experimental examples of two different SERS applications are given: one involving broad backgrounds (that do not vary much among spectra), and another that involves single molecule SERS (SM-SERS) measurements with narrower (and varying) backgrounds. In both cases, we will show that wavelet transforms can be used to fit the background with a great deal of accuracy, thus providing the framework for automatic background removal of large sets of data (typically obtained in time-series or spatial mappings). A MATLAB® based application that utilizes the iterative algorithm developed here is freely available to download from http://www.victoria.ac.nz/raman/publis/codes/cobra.aspx .
Hydrogen Bonding Interactions in Three 2-Mercaptoethanol Systems: An Excess Infrared Spectroscopic Study
Authors: Wang Nan-Nan , Li Qing-Zhong , Yu Zhi-Wu
Published: October 2010

The hydrogen bonding properties of a representative molecule, 2-mercaptoethanol (ME), of which two functional groups OH and SH are believed to interact competitively or selectively with proton-accepting molecules, have been studied. Three binary systems, namely ME–CCl4, ME–dimethyl sulfoxide (DMSO), and ME–acetone, were investigated with excess infrared absorption spectroscopy. It is found that when DMSO or acetone is added into ME, they preferentially form hydrogen bonds with OH, and the hydrogen bonds in the ME–DMSO system are stronger than those in the ME–acetone system. When CCl4 is added into ME, the weak hydrogen bonds involving the SH group are broken preferentially with increasing CCl4 concentration. The dissociation process of ME in the inert diluent CCl4 over the entire concentration range has been discussed in detail. In the very low concentration range of CCl4, the highly hydrogen bonded ME multimers mainly break into medium-sized aggregates. The amount of the trimers and dimers first increases and then, at x(CCl4) = 0.77, begins to decrease. These results suggest that excess infrared spectroscopy can provide detailed molecular pictures in liquid solutions containing complex hydrogen bonding interactions. It can also help to locate individual peak positions in the deconvolution of overlapped absorption bands.
Application of the Kubelka—Munk Correction for Self-Absorption of Fluorescence Emission in Carmine Lake Paint Layers
Authors: Clementi Catia , Miliani Costanza , Verri Giovanni , Sotiropoulou Sophia , Romani Aldo , Brunetti Brunetto G. , Sgamellotti A.
Published: October 2010

The variations of the fluorescence emission of carmine lake travelling through an absorbing and scattering medium, such as a paint layer, were investigated by ultraviolet (UV)–visible absorption, fluorescence spectroscopy, and imaging techniques. Samples of the lake were studied in dilute and saturated solutions, on a reference test panel and a real case study. Relevant spectral modifications have been observed as a function of the lake concentration mainly consisting of a fluorescence quenching, red shift of emission maxima, and deformation of emission band. The application of a correction factor based on the Kubelka–Munk model allowed fluorescence spectra obtained in solution and on painted samples of known composition to be compared and correlated, highlighting that the fluorescence of the lake within paint layers is affected by both self-absorption and aggregation phenomena. This approach has been successfully applied on a painting by G. Vasari for the noninvasive identification of carmine lake. The results reported here emphasize the necessity of taking physical phenomena into account in the interpretation of the fluorescence spectra for a proper and reliable characterization and identification of painting materials in works of art.
Removing Cosmic Ray Features from Raman Map Data by a Refined Nearest Neighbor Comparison Method as a Precursor for Chemometric Analysis
Authors: Cappel Ute B. , Bell Ian M. , Pickard Laura K.
Published: October 2010

An algorithm to remove cosmic ray (CR) features from Raman spectra collected in mapping experiments using a charge-coupled device (CCD) is presented. Each spectrum is compared to spectra collected from adjacent points in space using correlation values. The most similar neighbor (MSN) spectrum is selected, offset, and used for identification of CRs. The offset values are defined in terms of the noise level for data with a low signal-to-noise ratio and in terms of the peak height for data with a high signal-to-noise ratio. Scaled intensity values of the MSN spectra are used for replacement of contaminated pixels, allowing for full recovery of underlying spectral features. The algorithm is applicable for any Raman map where the particle sizes within the analyzed mixture are larger than the sampling size or to any other data where the sampling is more frequent than the variation, e.g., time series or temperature profiles. Its application to several maps of pharmaceutical samples is discussed here. With an appropriate offset value for the MSN spectra, no misdetections occur, and all CRs more intense than the offset are removed, which includes the CRs that would have hampered subsequent chemometric analysis by methods such as principal component analysis (PCA).
A Study of Ablation, Spatial, and Temporal Characteristics of Laser-Induced Plasmas Generated by Multiple Collinear Pulses
Authors: Galbács G. , Jedlinszki N. , Herrera K. , Omenetto N. , Smith B. W. , Winefordner J. D.
Published: October 2010

Multi-pulse laser-induced breakdown spectroscopy (LIBS) in the collinear pulse configuration with time-integrating detection was performed on metallic samples in ambient air in an effort to clarify the contributing processes responsible for the signal enhancement observed in comparison with single-pulse excitation. Complementary experiments were also carried out on another LIBS setup using detection by an imaging spectrograph with high time resolution. The effects of laser bursts consisting of up to seven ns-range pulses from Nd-doped solid-state lasers operating at their fundamental wavelength and separated by 8.5–50 μs time gaps was studied. The ablation and emission characteristics of the generated plasmas were investigated using light profilometry, microscopy, plasma imaging, emission distribution mapping, time-resolved line emission monitoring, and plasma temperature calculations. The experimental data suggest that the two contributing processes mainly responsible for the signal enhancement effect are the plume reheating caused by the sequential laser pulses and, more dominantly, the increased material ablation attributed to the lower breakdown threshold for the preheated (molten) sample surface and/or the reduced background gas pressure behind the shockwave of preceding pulses.
Synchrotron Infrared Confocal Microspectroscopical Detection of Heterogeneity within Chemically Modified Single Starch Granules
Authors: Wetzel David L. , Shi Yong-Cheng , Reffner John A.
Published: October 2010

This reports the first detection of chemical heterogeneity in octenyl succinic anhydride modified single starch granules using a Fourier transform infrared (FT-IR) microspectroscopical technique that combines diffraction-limited infrared microspectroscopy with a step size that is less than the mask projected spot size focused on the plane of the sample. The high spatial resolution was achieved with the combination of the application of a synchrotron infrared source and the confocal image plane masking system of the double-pass single-mask Continuμm® infrared microscope. Starch from grains such as corn and wheat exists in granules. The size of the granules depends on the plant producing the starch. Granules used in this study typically had a median size of 15 μm. In the production of modified starch, an acid anhydride typically is reacted with OH groups of the starch polymer. The resulting esterification adds the ester carbonyl (1723 cm−1) organic functional group to the polymer and the hydrocarbon chain of the ester contributes to the CH2 stretching vibration to enhance the intensity of the 2927 cm−1 band. Detection of the relative modifying population on a single granule was accomplished by ratioing the baseline adjusted peak area of the carbonyl functional group to that of a carbohydrate band. By stepping a confocally defined infrared beam as small as 5 μm × 5 μm across a starch granule 1 μm at a time in both the x and y directions, the heterogeneity is detected with the highest possible spatial resolution.
The Characterization of Phospholipid Functional Group Probe Species on Respirable Silicon-Containing Dusts by Solid-State 13C and 31P Nuclear Magnetic Resonance Spectroscopy
Authors: Murray David K.
Published: October 2010

Solid-state nuclear magnetic resonance (NMR) spectroscopic studies are reported for the interactions of probe molecules with respirable silicon-containing dusts as experimental evidence complementing computational studies reported by Snyder and Madura recently in J. Phys. Chem. B 112, 7095 (2008). The selected probe molecules represent the individual functional groups of a model lung surfactant dipalmitoylphosphatidyl choline (DPPC) deposited on a respirable silica and kaolin from water solution. 13C and 31P solid-state NMR spectroscopies were employed to detect chemical shift, line width, and chemical shift anisotropy, providing experimental evidence of mobility and relaxation changes describing the site and orientation of surface-associated species. NMR results confirm that only the phosphate and adjacent carbons are immobilized by surface hydroxyls on kaolin, while these and the carbons of the cationic head group are likewise immobilized by surface silanols on Miu-U-Sil 5. The phosphates in phosphoryl- and phosphatidyl-cholines were the primary interaction sites, with additional weak coordination with the trimethyl-ammonium cation species. Covalent Al–O–P formation is not likely a factor in in vivo or in vitro toxicity mechanisms of respirable silicon-containing materials, but is rather the result of dehydration or demethoxylation reactions occurring over time or during heating or reduced pressure used in preparing materials for NMR spectroscopic study. Hydration is a critical factor in the formation and preparation for spectroscopic observation of coated dusts. Care must be taken to ensure that products formed and studied correspond to species formed in vivo under suitable concentration and hydration conditions.
Spectral Sharpening Algorithm for a Polychromatic Reflectometer in the Extreme Ultraviolet
Authors: Banyay M. , Juschkin L.
Published: October 2010

In this paper we present a practical approach to the analysis of spectra recorded from a table-top reflectometer operating in the extreme ultraviolet (UV) spectral range. Such in-lab tools, which utilize light from plasma based sources, are currently under investigation for a broad range of applications such as surface and thin-film analysis, near-edge X-ray absorption fine structure (NEXAFS) studies, or reflectivity measurements. In a polychromatic approach one is able to record surface-sensitive reflectometric spectra that are characteristic for each material or thin-film-layer stack. By monitoring the incident and emergent spectrum before and after the sample using two independent detectors, one can deduce its reflectivity. However, the analysis of the raw data, in terms of digitized spectrometric intensity values, can be difficult due to the nature of the quasi-continuous emission from such plasma sources, particularly with xenon, which is a good broad-band radiator in the 10–20 nm spectral range. The complexity of configurations involved in transitions of highly ionized xenon makes a line-by-line analysis very difficult as the real spectrum consists of thousands of unresolved transitions superimposed by distinctive lines. Additionally, sampling issues, detector geometry, and minor setup misalignments can distort the result. We propose a practical algorithm for spectral decomposition and sharpening of such data. Measurement results are presented that confirm the functionality of the algorithm.
Utilization of the Coherence Function with Welch's Method for Signal Analysis in Low Resolution Laser-Induced Breakdown Spectroscopy
Authors: O'Leary Brendon , Kelley Jude A.
Published: October 2010

This work presents a technique by which a low resolution (≈1 nm) fiber-optic spectrometer may be used to definitively identify elements and molecular fragments in laser-induced breakdown spectroscopy. Commercial laser-induced breakdown spectroscopy (LIBS) spectrometers have high resolution in the area of spectral interest, and software is used to identify elements via a look-up table containing known spectral lines. When analyzing spectra from a lower resolution fiber-optic spectrometer, software based on look-up tables can produce erroneous results, reporting elements absent from the sample. As a solution to this problem, an analysis using the coherence function in conjunction with Welch's method is used to compare sample spectra with a library of reference spectra, which contain peaks primarily from a single element. The analysis has proved to be adept at identifying specific elemental signatures in multi-component samples. The technique leverages the increased information content of concomitant atomic emission lines, which are easily collected with a low resolution broadband (200–1100 nm) fiber-optic spectrometer. This technique alleviates the need for the user to visually verify the vicinity of individual peaks during testing. While Pearson's method is generally used for this type of analysis, we show that Welch's method has the advantage of being less susceptible to problems caused by continuum background.
Demonstration of a New Laser Diagnostic Based on Photodissociation Spectroscopy for Imaging Mixture Fraction in a Non-Premixed Jet Flame
Authors: Zhao Yan , Tong Chenning , Ma Lin
Published: October 2010

The study of turbulent combustion calls for new diagnostics that can measure multidimensional mixture fraction under a wide range of flame conditions. A laser diagnostic technique based on photodissociation spectroscopy (PDS) is proposed to address this need. This paper describes the concept of the PDS-based diagnostic, reports its experimental demonstration in a non-premixed jet flame, and assesses its performance and applicable range. This new technique is centered around the creative use of photodissociation (PD) for flow visualization. A carefully chosen PD precursor is seeded into the flow of interest to measure mixture fraction. The precursor is chosen such that (1) both the precursor itself and the products formed from the precursor (if it reacts) can be completely and rapidly photodissociated; thus, the concentration of one of the photofragments forms a conserved scalar and can be used to infer the mixture fraction, and (2) the target photofragment offers friendly spectroscopic properties (e.g., strong laser-induced fluorescence signals and/or simple signal interpretation) so multidimensional imaging can be readily obtained. Molecular iodine (I2) was identified as a precursor satisfying both requirements and was seeded into a carbon monoxide (CO)–air jet flame for single-shot two-dimensional imaging of mixture fraction. This demonstration illustrates the potential of the PDS-based technique to overcome the limitations of existing techniques and to provide multidimensional measurements of mixture fraction in a variety of reactive flows.
Monitoring of the Thickness of Ultraviolet-Cured Pigmented Coatings and Printed Layers by Near-Infrared Spectroscopy
Authors: Heymann Katja , Mirschel Gabriele , Scherzer Tom
Published: October 2010

Near-infrared (NIR) reflection spectroscopy was used for the determination of the thickness or the coating weight, respectively, of white-pigmented acrylic coatings and layers of printing inks. The thickness of coatings was studied in the range from 5 to 60 μm, whereas the coating weights of the printed layers covered a range between 1 to 5 g m−2. Quantitative analysis of the spectral data relied on partial least squares (PLS) regression. A thickness gauge or gravimetry, respectively, were used to obtain reference data. Calibration models were typically based on six factors. The corresponding root mean square errors of prediction (RMSEP) were found to be on the order of 0. 87 for coatings and 0. 38 for printed layers. Monitoring of the coating thickness under process conditions was carried out on a pilot-scale roll coating machine. In order to simulate thickness changes during a coating process, either the nip between the applicator rolls or the web speed was varied. Data with high precision (standard deviation ∼1 μm for coatings, ∼0.4 g m−2 for printed layers) and an excellent correlation with off-line reference data were obtained. The investigations have shown that NIR spectroscopy can be used for process control in coating and curing technology.
Dual-Wavelength Raman Spectroscopy Approach for Studying Fluid-Phase Equilibria Using a Single Laser
Authors: Kiefer Johannes
Published: October 2010

A novel Raman spectroscopy setup for the investigation of multiphase fluid mixtures is proposed. The total output of a frequency-doubled Nd:YAG laser is separated into a strong 532 nm beam for generating Raman signals in the vapor phase and the weak residual of the fundamental 1064 nm radiation to be utilized as laser source for Raman scattering in the liquid phase. This approach will provide sufficient signal intensity from the gas (despite low density) for determination of mixture composition and at the same time it facilitates recording high-resolution spectra from the liquid in order to allow studying molecular physics phenomena together with concentration measurements.
The Use of Laser-Induced Breakdown Spectroscopy for Distinguishing between Bacterial Pathogen Species and Strains
Authors: Multari Rosalie A. , Cremers David A. , Dupre Joanne M. , Gustafson John E.
Published: October 2010

Laser-induced breakdown spectroscopy (LIBS) was used in a blind study to successfully differentiate bacterial pathogens, both species and strain. The pathogens used for the study were chosen and prepared by one set of researchers. The LIBS data were collected and analyzed by another set of researchers. The latter researchers had no knowledge of the sample identities other than that (1) the first five of fifteen samples were unique (not replicates) and (2) the remaining ten samples consisted of two replicates of each of the first five samples. Using only chemometric analysis of the LIBS data, the ten replicate bacterial samples were successfully matched to each of the first five samples. The results of this blind study show it is possible to differentiate the bacterial pathogens Escherichia coli, three clonal methicillin-resistant Staphylococcus aureus (MRSA) strains, and one unrelated MRSA strain using LIBS. This is an important finding because it demonstrates that LIBS can be used to determine bacterial pathogen species within a defined sample set and can be used to differentiate between clonal relationships among strains of a single multiple-antibiotic-resistant bacterial species. Such a capability is important for the development of LIBS instruments for use in medical, water, and food safety applications.
Variability in Raman Spectra of Single Human Tumor Cells Cultured in vitro: Correlation with Cell Cycle and Culture Confluency
Authors: Matthews Quinn , Jirasek Andrew , Lum Julian , Duan Xiaobo , Brolo Alexandre G.
Published: October 2010

In this work we investigate the capability of Raman microscopy (RM) to detect inherent sources of biochemically based spectral variability between single cells of a human tumor cell line (DU145) cultured in vitro. Principal component analysis (PCA) is used to identify differences in single-cell Raman spectra. These spectral differences correlate with (1) cell cycle progression and (2) changing confluency of a cell culture during the first 3 to 4 days after sub-culturing. Cell cycle regulatory drugs are used to synchronize the cell cycle progression of cell cultures, and flow cytometry is used to determine the cell cycle distribution of cell cultures at the time of Raman analysis. Spectral variability arising from cell cycle progression is (1) expressed as varying intensities of protein and nucleic acid features relative to lipid features, (2) well correlated with known biochemical changes in cells as they progress through the cell cycle, and (3) shown to be the most significant source of inherent spectral variability between cells. Furthermore, the specific biomolecules responsible for the observed spectral variability due to both cell cycle progression and changes in cell culture confluency can be identified in the first and second components of principal component analysis (PCA). Our characterization of the inherent sources of variability in Raman spectra of single human cells will be useful for understanding subtle spectral differences in RM studies of single cells.
Rapid Simultaneous Determination of Four Non-Steroidal Anti-Inflammatory Drugs by Means of Derivative Nonlinear Variable-Angle Synchronous Fluorescence Spectrometry
Authors: Pulgarín José A. Murillo , Molina Aurelia Alañón , Robles Ignacio Sánchez-Ferrer
Published: October 2010

A rapid, simple, and inexpensive spectrofluorimetric method has been proposed for the simultaneous quantification of diflunisal, salicylic acid, fenoprofen, and 6-methoxy-2-naphthylacetic acid (6MNA). First-derivative nonlinear variable-angle synchronous fluorescence spectrometry has been developed to improve the selectivity of fluorescence measurements without loss of sensitivity. It allows the simultaneous determination of different substances in a mixture from a single spectrum based on a single scan. The analyses were performed in an ethanol–water (70%) medium at a pH of 9.2, adjusted by using ammonium/ammonia (0.5 M) as a buffer solution. The linear concentration ranges are 30.0–100.0, 100.0–600.0, 50.0–150.0, and 30.0–100.0 ng/mL for salicylic acid, fenoprofen, diflunisal, and 6-methoxy-2-naphthylacetic acid, respectively, at λex/λem = 281.1/423.6, 241.2/301.2, 284.1/403.8, and 268.7/339.6 nm, respectively. Analytical parameters of the proposed method were calculated according to the error propagation theory. The sensitivity, repeatability, reproducibility, and limits of detection achieved with the proposed method are adequate for the determination of these anti-inflammatory drugs.
Evaluation of the Bioconjugation Efficiency of Different Quantum Dots as Probes for Immunostaining Tumor-Marker Proteins
Authors: Xu Hao , Chen Chuang , Peng Jun , Tang Hong-Wu , Liu Chun-Mei , He Yue , Chen Ze-Zhong , Li Yan , Zhang Zhi-Ling , Pang Dai-Wen
Published: October 2010

The differing bioconjugation efficiencies of quantum dots (QDs) are a practical obstacle to their popularization. Differences in bioconjugation efficiency based on immunostaining the same targeted molecules using different batches of QDs need to be evaluated prior to their application. In this paper, a quantitative method for evaluating the efficiency of QDs in staining tissues has been developed based on Hadamard transform (HT) spectral imaging. Proliferating cell nuclear antigens (PCNA) in breast cancer tissues were labeled with bioconjugated QD bioprobes using a 454 nm laser as the light source for fluorescence spectral imaging. Four-dimensional (4D) spectral imaging analysis of PCNA in cell nuclei was carried out using HT spectral microscopy based on immunostaining with different batches of QDs. The fluorescence intensity distributions in the cell nuclei were collected from the 4D images. Based on the information obtained from microscopic spectra and 4D images, differences in the bioconjugation efficiency among different batches of QDs were evaluated. The results demonstrate that it is possible to maintain uniform bioconjugation efficiencies with different QD bioconjugation processes in order to obtain accurate and reliable results in biomedical analysis and cancer diagnosis.
Comparison of the Use of Volume Fractions with other Measures of Concentration for Quantitative Spectroscopic Calibration Using the Classical Least Squares Method
Authors: Mark Howard , Rubinovitz Ronald , Heaps David , Gemperline Paul , Dahm Donald , Dahm Kevin
Published: October 2010

Since the commercial development of modern near-infrared spectroscopy in the 1970s, analysts have almost invariably used units of weight percent as the measure of analyte concentration, due largely to the historical precedent from other analytical methods, including other spectroscopic techniques. The application of the CLS algorithm to a set of binary and ternary liquid mixtures reveals that the spectroscopic measurement sees the sample differently; that the measured absorbance spectrum is in fact sensitive to the volume fraction of the various components of the mixture. Because there is not a one-to-one relationship between volume fraction and other measures of analyte concentration, nor is the relationship linear, this has important implications for the application of both the CLS algorithm and the various other, more conventional, calibration algorithms that are commonly used.
Fast Elemental Screening of Soil and Sediment Profiles Using Small-Spot Energy-Dispersive X-Ray Fluorescence: Application to Mining Sediments Geochemistry
Authors: Gonzalez-Fernandez Oscar , Queralt Ignacio
Published: October 2010

Elemental analysis of different sediment cores originating from the Cartagena–La Union mining district in Spain was carried out by means of a programmable small-spot energy-dispersive X-ray fluorescence (EDXRF) spectrometer to study the distribution of heavy metals along soil profiles. Cores were obtained from upstream sediments of a mining creek, from the lowland sedimentation plain, and from a mining landfill dump (tailings pile). A programmable two-dimensional (2D) stage and a focal spot resolution of 600 μm allow us to obtain complete core mapping. Geochemical results were verified using a more powerful wavelength-dispersion X-ray fluorescence (WDXRF) technique. The data obtained was processed in order to study the statistical correlations within the elemental compositions. The results obtained allow us to observe the differential in-depth distribution of heavy metals among the sampled zones. Dump site cores exhibit a homogeneous distribution of heavy metals, whereas the alluvial plain core shows accumulation of heavy metals in the upper part. This approach can be useful for the fast screening of heavy metals in depositional environments around mining sites.
Applications of Microstructured Silicon Wafers as Internal Reflection Elements in Attenuated Total Reflection Fourier Transform Infrared Spectroscopy
Authors: Schumacher Henrik , Künzelmann Ulrich , Vasilev Boris , Eichhorn Klaus-Jochen , Bartha Johann W.
Published: October 2010

A novel internal reflection element (IRE) for attenuated total reflection Fourier transform infrared (ATR-FT-IR) spectral acquisition is introduced and applied for several surface-sensitive measurements. It is based on microstructured double-side-polished (100) silicon wafers with v-shaped grooves of {111} facets on their backside. These facets of the so-called “microstructured single-reflection elements” (mSRE) are formed by a crystal-oriented anisotropic wet etching process within a conventional wafer structuring process. They are used to couple infrared radiation into and out of the IRE. In contrast to the application of the commonly used silicon multiple-reflection elements (MRE), the new elements provide single-reflection ATR measurements at the opposite wafer side by using simple reflection accessories without any special collimation. Due to the short light path, the spectral range covers the entire mid-infrared region with a high optical throughput, including the range of silicon lattice vibrations from 300 to 1500 cm−1. In addition to typical ATR applications, i.e., the measurement of bulk liquids and soft materials, the new reflection elements can be effectively used and customer-specifically designed for in situ and ex situ investigations of aqueous solutions, thin films, and monolayers on Si. Examples presented in this article are in situ etching of native as well as thermal SiO2 and characterization of polydimethylsiloxane (PDMS) films on Si under various measuring conditions.
Characterization of Fungal-Degraded Lime Wood by X-Ray Diffraction and Cross-Polarization Magic-Angle-Spinning 13C-Nuclear Magnetic Resonance Spectroscopy
Authors: Popescu Carmen-Mihaela , Larsson Per Tomas , Tibirna Carmen Mihaela , Vasile Cornelia
Published: October 2010

X-ray diffraction, scanning electron microscopy (SEM), and solid-state cross-polarization magic-angle-spinning (CP/MAS) 13C-NMR spectroscopy were applied to determine changes over time in the morphology and crystallinity of lime wood ( Tilia cordata Miller) generated by the soft-rot fungi. Wood samples were inoculated with Trichoderma viride Pers for various durations up to 84 days. Structural and morphological modifications were assessed by comparing the structural features of decayed lime wood samples with references. Significant morphology changes such as defibration or small cavities were clearly observed on the SEM micrographs of lime wood samples exposed to fungi. Following the deconvolution process of the diffraction patterns, the degree of crystallinity, apparent lateral crystallite size, the proportion of crystallite interior chains, and the cellulose fraction have been determined. It was found that all crystallographic data vary with the duration of exposure to fungi. The degree of crystallinity and cellulose fraction tend to decrease, whereas the apparent lateral crystallite size and the proportion of crystallite interior chains increase with prolonged biodegradation processes. The most relevant signals in CP/MAS 13C-NMR spectra were assigned according to literature data. The differences observed were discussed in terms of lignin and cellulose composition: by fixing the lignin reference signal intensity, the cellulose and hemicelluloses moieties showed a relative decrease compared to the lignin signals in decayed wood.
Dynamics within Site Selectively Templated and Tagged Xerogel Sensor Platforms
Authors: Bright Frank V. , Holthoff Ellen L.
Published: October 2010

In a nitrobenzo-2-oxa-1,3-diazole (NBD) -based, 9-anthrol-responsive site selectively templated and tagged xerogel (SSTTX) sensor platform, there are two reporter molecule site types (responsive and non-responsive) that are responsible for the observed fluorescence signals. These NBD sites function independently. Site 1 alone binds the target analyte and yields an analyte-dependent signal. This signal arises from analyte binding decreasing the photo-induced electron transfer (PET) efficiency between a strategically placed amine residue and the excited NBD reporter molecule within the template site. Site 2 does not respond to analyte, it is not fully formed, and it manifests itself as a background signal. In an n-octyl residue-free SSTTX, the local microviscosity sensed by the site 1 NBD reporter molecules in the absence and presence of target analyte is ∼260 cP and ∼540 cP, respectively. These local microviscosity values are substantially greater in comparison to free NBD dissolved in THF (η = 0.46 cP at 298 K, φ ∼ 25 ps). As the SSTTX n-octyl content is increased, the local microviscosity sensed by the site 1 NBD reporter molecules in the absence and presence of target analyte is ∼360 cP and ∼760 cP, respectively. This behavior is consistent with the n-octyl chains crowding the cybotactic region surrounding the site 1 NBD reporter molecules. This n-octyl-induced site 1 “crowding” is also associated with improved analyte binding to site 1 and better overall SSTTX analytical performance.
Characterization of the New Serum Protein Reference Material ERM-DA470k/IFCC: Value Assignment by Immunoassay
Authors: Zegers Ingrid , Keller Thomas , Schreiber Wiebke , Sheldon Joanna , Albertini Riccardo , Blirup-Jensen Søren , Johnson Myron , Trapmann Stefanie , Emons Hendrik , Merlini Giampaolo , Schimmel Heinz
Published: October 2010

BACKGROUND

The availability of a suitable matrix reference material is essential for standardization of the immunoassays used to measure serum proteins. The earlier serum protein reference material ERM-DA470 (previously called CRM470), certified in 1993, has led to a high degree of harmonization of the measurement results. A new serum protein material has now been prepared and its suitability in term of homogeneity and stability has been verified; after characterization, the material has been certified as ERM-DA470k/IFCC.

METHODS

We characterized the candidate reference material for 14 proteins by applying a protocol that is considered to be a reference measurement procedure, by use of optimized immunoassays. ERM-DA470 was used as a calibrant.

RESULTS

For 12 proteins [α2 macroglobulin (A2M), α1 acid glycoprotein (orosomucoid, AAG), α1 antitrypsin (α1-protease inhibitor, AAT), albumin (ALB), complement 3c (C3c), complement 4 (C4), haptoglobin (HPT), IgA, IgG, IgM, transferrin (TRF), and transthyretin (TTR)], the results allowed assignment of certified values in ERM-DA470k/IFCC. For CRP, we observed a bias between the lyophilized and liquid frozen materials, and for CER, the distribution of values was too broad. Therefore, these 2 proteins were not certified in the ERM-DA470k/IFCC. Different value transfer procedures were tested (open and closed procedures) and found to provide equivalent results.

CONCLUSIONS

A new serum protein reference material has been produced, and values have been successfully assigned for 12 proteins.
Oscillatory Dipoles As a Source of Phase Shifts in Field Potentials in the Mammalian Auditory Brainstem
Authors: Mc Laughlin Myles , Verschooten Eric , Joris Philip X.
Published: October 2010

A popular model of binaural processing, proposed by Jeffress (1948), states that external interaural time delays (ITDs) are compensated by internal axonal delays allowing ITD to be spatially represented by a population of coincidence detectors in the medial superior olive (MSO). Isolating single-neuron responses in MSO is difficult because of the presence of a strong extracellular field potential known as the neurophonic, so that few studies have tested Jeffress's key prediction. Phase delays in the nucleus laminaris neurophonic in owls have been observed and are consistent with a Jeffress-like model. Here, we recorded neurophonic responses in cat MSO to monaural tones at locations along its dendritic axis. Fourier analysis of the neurophonic was used to extract amplitude and phase at the stimulus frequency. Amplitude, as a function of depth, showed two peaks separated by a dip. A half-cycle phase shift was observed at depths close to the dip, over a wide frequency range. Current source density analysis for contralateral (ipsilateral) stimulation shows a current source close to the neurophonic amplitude peak and a sink a few hundred micrometers ventromedially (dorsolaterally). These results are consistent with a dipole configuration: contralateral (ipsilateral) excitation causes a current sink at the ventromedial (dorsolateral) dendrites and a source at the soma and dorsolateral (ventromedial) dendrites. Incorporating these results in a dipole model explains the phase and amplitude patterns observed. We conclude that the half-cycle phase shift is consistent with a current dipole, making it difficult to derive measurements of axonal delays from the neurophonic.
Spatiotemporal Coupling between Hippocampal Acetylcholine Release and Theta OscillationsIn Vivo
Authors: Zhang Hao , Lin Shih-Chieh , Nicolelis Miguel A. L.
Published: October 2010

Both acetylcholine (ACh) and theta oscillations are important for learning and memory, but the dynamic interaction between these two processes remains unclear. Recent advances in amperometry techniques have revealed phasic ACh releasesin vivo. However, it is unknown whether phasic ACh release co-occurs with theta oscillations. We investigated this issue in the CA1 region of urethane-anesthetized male rats using amperometric and electrophysiological recordings. We found that ACh release was highly correlated with the appearance of both spontaneous and induced theta oscillations. Moreover, the maximal ACh release was observed around or slightly above the pyramidal layer. Interestingly, such release lagged behind theta initiation by 25–60 s. The slow ACh release profile was matched by the slow firing rate increase of a subset of medial–septal low-firing-rate neurons. Together, these results establish, for the first time, thein vivocoupling between phasic ACh release and theta oscillations on spatiotemporal scales much finer than previously known. These findings also suggest that phasic ACh is not required for theta initiation and may instead operate synergistically with theta oscillations to promote neural plasticity in the service of learning and memory.
POSH is an Intracellular Signal Transducer for the Axon Outgrowth Inhibitor Nogo66
Authors: Dickson Heather M. , Zurawski Jonathan , Zhang Huanqing , Turner David L. , Vojtek Anne B.
Published: October 2010

Myelin-derived inhibitors limit axon outgrowth and plasticity during development and in the adult mammalian CNS. Nogo66, a functional domain of the myelin-derived inhibitor NogoA, signals through the PirB receptor to inhibit axon outgrowth. The signaling pathway mobilized by Nogo66 engagement of PirB is not well understood. We identify a critical role for the scaffold protein Plenty of SH3s (POSH) in relaying process outgrowth inhibition downstream of Nogo66 and PirB. Blocking the function of POSH, or two POSH-associated proteins, leucine zipper kinase (LZK) and Shroom3, with RNAi in cortical neurons leads to release from myelin and Nogo66 inhibition. We also observed autocrine inhibition of process outgrowth by NogoA, and suppression analysis with the POSH-associated kinase LZK demonstrated that LZK operates downstream of NogoA and PirB in a POSH-dependent manner. In addition, cerebellar granule neurons with an RNAi-mediated knockdown in POSH function were refractory to the inhibitory action of Nogo66, indicating that a POSH-dependent mechanism operates to inhibit axon outgrowth in different types of CNS neurons. These studies delineate an intracellular signaling pathway for process outgrowth inhibition by Nogo66, comprised of NogoA, PirB, POSH, LZK, and Shroom3, and implicate the POSH complex as a potential therapeutic target to enhance axon outgrowth and plasticity in the injured CNS.
Convergence of Presenilin- and Tau-Mediated Pathways on Axonal Trafficking and Neuronal Function
Authors: Peethumnongsin Erica , Yang Li , Kallhoff-Muñoz Verena , Hu Lingyun , Takashima Akihiko , Pautler Robia G. , Zheng Hui
Published: October 2010

Alzheimer's disease (AD) is a significant and growing health problem in the aging population. Although definitive mechanisms of pathogenesis remain elusive, genetic and histological clues have implicated the proteins presenilin (PS) and tau as key players in AD development. PS mutations lead to familial AD, and although tau is not mutated in AD, tau pathology is a hallmark of the disease. Axonal transport deficits are a common feature of several neurodegenerative disorders and may represent a point of intersection of PS and tau function. To investigate the contribution of wild-type, as opposed to mutant, tau to axonal transport defects in the context of presenilin loss, we used a mouse model postnatally deficient for PS (PS cDKO) and expressing wild-type human tau (WtTau). The resulting PS cDKO;WtTau mice exhibited early tau pathology and axonal transport deficits that preceded development of these phenotypes in WtTau or PS cDKO mice. These deficits were associated with reduced neurotrophin signaling, defective learning and memory and impaired synaptic plasticity. The combination of these effects accelerated neurodegeneration in PS cDKO;WtTau mice. Our results strongly support a convergent role for PS and tau in axonal transport and neuronal survival and function and implicate their misregulation as a contributor to AD pathogenesis.
Transcriptional Control ofKCNQChannel Genes and the Regulation of Neuronal Excitability
Authors: Mucha Mariusz , Ooi Lezanne , Linley John E. , Mordaka Pawel , Dalle Carine , Robertson Brian , Gamper Nikita , Wood Ian C.
Published: October 2010

Regulation of the resting membrane potential and the repolarization of neurons are important in regulating neuronal excitability. The potassium channel subunits Kv7.2 and Kv7.3 play a key role in stabilizing neuronal activity. Mutations inKCNQ2andKCNQ3, the genes encoding Kv7.2 and Kv7.3, cause a neonatal form of epilepsy, and activators of these channels have been identified as novel antiepileptics and analgesics. Despite the observations that regulation of these subunits has profound effects on neuronal function, almost nothing is known about the mechanisms responsible for controlling appropriate expression levels. Here we identify two mechanisms responsible for regulatingKCNQ2andKCNQ3mRNA levels. We show that the transcription factor Sp1 activates expression of bothKCNQ2andKCNQ3, whereas the transcriptional repressor REST (repressor element 1-silencing transcription factor) represses expression of both of these genes. Furthermore, we show that transcriptional regulation ofKCNQgenes is mirrored by the correlated changes in M-current density and excitability of native sensory neurons. We propose that these mechanisms are important in the control of excitability of neurons and may have implications in seizure activity and pain.
Role of the Cerebellar Cortex in Conditioned Goal-Directed Behavior
Authors: Burguière Eric , Arabo Arnaud , Jarlier Frederic , De Zeeuw Chris I. , Rondi-Reig Laure
Published: October 2010

Learning a new goal-directed behavioral task often requires the improvement of at least two processes, including an enhanced stimulus–response association and an optimization of the execution of the motor response. The cerebellum has recently been shown to play a role in acquiring goal-directed behavior, but it is unclear to what extent it contributes to a change in the stimulus–response association and/or the optimization of the execution of the motor response. We therefore designed the stimulus-dependent water Y-maze conditioning task, which allows discrimination between both processes, and we subsequently subjected Purkinje cell-specific mutant mice to this new task. The mouse mutants L7-PKCi, which suffer from impaired PKC-dependent processes such as parallel fiber to Purkinje cell long-term depression (PF-PC LTD), were able to acquire the stimulus–response association, but exhibited a reduced optimization of their motor performance. These data show that PF-PC LTD is not required for learning a stimulus–response association, but they do suggest that a PKC-dependent process in cerebellar Purkinje cells is required for optimization of motor responses.
Tuning Curves for Movement Direction in the Human Visuomotor System
Authors: Fabbri Sara , Caramazza Alfonso , Lingnau Angelika
Published: October 2010

Neurons in macaque primary motor cortex (M1) are broadly tuned to arm movement direction. Recent evidence suggests that human M1 contains directionally tuned neurons, but it is unclear which other areas are part of the network coding movement direction and what characterizes the responses of neuronal populations in those areas. Such information would be highly relevant for the implementation of brain–computer interfaces (BCIs) in paralyzed patients. We used functional magnetic resonance imaging adaptation to identify which areas of the human brain show directional selectivity and the degree to which these areas are affected by the type of motor act (to press vs to grasp). After adapting participants to one particular hand movement direction, we measured the release from adaptation during occasional test trials, parametrically varying the angular difference between adaptation and test direction. We identified multiple areas broadly tuned to movement direction, including M1, dorsal premotor cortex, intraparietal sulcus, and the parietal reach region. Within these areas, we observed a gradient of directional selectivity, with highest directional selectivity in the right parietal reach region, for both right- and left-hand movements. Moreover, directional selectivity was modulated by the type of motor act to varying degrees, with the largest effect in M1 and the smallest modulation in the parietal reach region. These data provide an important extension of our knowledge about directional tuning in the human brain. Furthermore, our results suggest that the parietal reach region might be an ideal candidate for the implementation of BCI in paralyzed patients.