Peak Height Ratio Research Articles

An unbalanced tri-allelic pattern at the D10S1248 locus: Characteristics, genetic basis and transmission.

To address issues related to unbalanced tri-allelic patterns, an example at the D10S1248 locus characterized by the sum of heights of alleles 13 and 15 approximately equal to allele 14 was intensively investigated. The coexistence of these three alleles was confirmed by profiling the rs2246512-D10S1248 marker using fluorescently labelled primers and allelic sequencing. Multi-tissue genotyping revealed that this pattern had chimeric characteristics, and pedigree analysis found that allele 13 or allele 14 were inherited to offspring independently of the other two alleles. These evidences suggest that the pattern should stem from a somatic mutation in early embryonic development and that peak height ratio is not an accurate indicator of mutation time point and direction. The rs2246538-D10S1248-rs2246512 marker was subsequently used to determine the mutation from allele 15 to allele 13. Notably, allele 13 with the lowest peak height was misidentified as a stutter peak when genotyped using next generation sequencing.

A comparative study of whole genome amplification and low-template DNA profiling

Generation of high-quality STR profiles from trace amounts of cells remains challenging. Although increasing the number of PCR cycles improves the sensitivity of STR analysis, stochastic effects may complicate interpretation and deem the profiles inconclusive. Whole Genome Amplification (WGA) has been successfully employed to improve the outcome of subsequent STR analysis by increasing the number of available DNA template. However, there is limited information on how WGA performs in comparison to the elevated PCR cycles.This study aims to evaluate the quality of STR profiles obtained from 10 and 25 pg of DNA that had undergone WGA, against that from 32-PCR cycle protocol. Buccal cell DNA was subjected to 16-h WGA using REPLI-g® Single Cell Kit followed by 28-cycle STR amplification with AmpFLSTR™ Identifiler™ Plus PCR Amplification Kit. The results showed that the WGA yielded significantly lower allele detection rates than the 32-cycle PCRs, although the mean peak height ratios were comparable. Few allelic drop-ins were also observed in profiles derived from the WGA products, while none was present in the 32-cycle PCR profiles. These preliminary data suggested that the WGA protocol examined did not offer any improvement on DNA profile quality over the elevated PCR cycle method. However, the success rates of the WGA in this study seemed to contradict the previous reports, thus modifications to the protocol used would be further investigated.

Evaluation of vaginal mRNA markers in women from different age groups: A GeFI collaborative study

Forensic mRNA profiling assays normally include a set of vaginal-specific markers. Although it is known that vagina undergoes characteristic age-related morphological and physiological changes over a lifetime, few studies have evaluated the efficacy of proposed forensic vaginal mRNA markers in women from different age groups.In this collaborative study involving ten GeFI (Italian working group of ISFG) laboratories, a 19-plex mRNA profiling assay including three vaginal-specific markers (CYP2B7P1, MUC4, MYOZ1) was tested in a collection of vaginal swabs obtained from female volunteer donors in their reproductive years (n = 84) and postmenopausa (n = 55).Differential expression of vaginal markers in the two age categories was assessed by means of: a) overall success rate of mRNA profiling (vaginal mucosa “observed” in the tested sample according to scoring protocol) b) average peak height ratios between vaginal-specific markers within mRNA profiling replicates.Other factors potentially influencing mRNA profiling outcomes, like time interval between vaginal swab collection and analysis, concurrence of menstrual cycle and recent sexual activity at the time of sampling were also investigated.

Evaluation of Dry-Wet Transition in PEFC Under Load Changes Based on Laser Spectroscopy Using Fiber-Optic Probe

The low-humidity operations of a polymer electrolyte fuel cell (PEFC) unfortunately induce the membrane dehydration and deteriorate the proton conductivity through the membrane. Especially, when the output current rapidly rises in steps under load-change conditions, the remarkable decrease of the water concentration on the anode side temporarily occurs and it causes the sudden drop of cell voltage called the “undershoot”. To alleviate this issue, it’s necessary to grasp the dry-wet transition in a PEFC operated under low-humidity and load-change conditions. In the previous studies, the transient water distribution along flow fields of operating PEFCs was vigorously investigated using gas chromatography (GC) [1]. Although GC techniques provide more accurate gas concentrations in flow channels, it takes a long time (at least two minutes) to collect a gas sample and identify a species. As an alternative approach, several researchers have applied tunable diode laser absorption spectroscopy (TDLAS) to the measurement of the water transport in working PEFCs [2,3]. TDLAS is one of the high-speed and high-sensitive absorption spectroscopy techniques which detect the absorbance of a chemical species and identify its concentration using infrared diode laser. Since the laser beam is directly injected into gas channels of PEFCs, the in-situ monitoring of water vapor concentration can be performed on operational fuel cells with a high time resolution of millisecond. However, it’s difficult to sufficiently secure the laser beam path within millimeter-scale narrow channels. In addition, the injection of laser beam into narrow channels tends to generate optical fringe noise due to the multiple reflection. To further enhance the sensitivity and accuracy of gas sensing, it’s necessary to improve the optical system of TDLAS inside fuel cell channels. The authors developed a new TDLAS-based gas sensing system with a single-ended fiber-optic probe to highly accurately measure the water vapor distribution in narrow flow channels of fuel cells at high speed. Fig. 1 shows the schematic diagram of the gas sensor developed in this study. The small-size single-ended probe with pitch and catch fibers enables the in-situ laser diagnostics within millimeter-scale narrow channels. In this measurement system, wavelength modulation spectroscopy (WMS) technique is adopted for high-sensitive gas detection. Furthermore, multiple detection signals are synthesized to cancel the fringe noise and improve the S/N ratio. The fiber-optic probe is directly inserted into the serpentine flow field (241 mm length, 1.0 mm width, 1.0 mm depth) of the experimental fuel cell, and the triangular modulated beam emitted from a DFB laser diode (Wavelength: 1392.5 nm) is injected into a channel through the single-mode pitch fiber. The back-reflection lights from the electrode surface are captured by six multi-mode catch fibers and converted electric signals by six photodiodes (PDs). After six signals are synthesized, the composite signal is transmitted to a lock-in amplifier and the second-harmonic (2f) spectra are obtained by phase-sensitive detection. The mole fraction of water vapor can be estimated from the peak height ratio of 2f and 4f spectra. This gas sensor was applied to evaluate the dry-wet transition in the anode channel of an operating PEFC under low-humidity and load change conditions. Fig. 2 presents the dynamic response of cell voltage and the transient water concentrations along the anode channel of a PEFC during the low-humidity and current-cycling operation. The repetitive current cycling was performed between 0.2 A/cm2 for 23 s, and 0.6 A/cm2 for 23 s. The inlet gas humidifications of the anode and cathode are 45 and 0% RH, respectively. When the current density is rapidly increased from 0.2 to 0.6 A/cm2, the large undershoot of cell voltage is observed because the water content at the anode side of the membrane is suddenly decreased by the strong electro-osmotic effect and the proton conductivity is deteriorated. It can also be seen that the water vapor concentration in the anode channel temporarily and largely drops in the downstream section (x/L=0.5-0.8). After the voltage undershoot, the cell voltage is gradually recovered because the back-diffusion of product water hydrates the membrane from the cathode to anode and reduces its ohmic resistance. The water concentration in the anode channel is gradually increased by the back-diffusion effect. It was found that the TDLAS-based gas sensing technique enables to detect the instantaneous fluctuation of water concentration in flow channels of PEFCs during load-change operations.

Differences in Meibum and Tear Lipid Composition and Conformation.

The compositional, structural, and functional relationships of meibum may provide insights into the loss of tear film stability. Although the conformation of meibum lipids has been studied rigorously, that of tear lipids has not. Tear lipids (TLHSCT) and meibum (MHSCT) from patients who had hematopoietic stem cell transplantation were pooled prospectively. The infrared spectra of meibum from donors with (MMGD) and without (Mn) meibomian gland dysfunction were retrospectively analyzed to measure the lipid composition and structure. The infrared CH stretching region was used to measure the relative content of CH3 and CH2 moieties in the meibum. The 3 major findings of the current study are as follows: 1) compared with Mn, MHSCT and MMGD had 18% fewer CH3 moieties; 2) compared with MHSCT, the phase transition temperature, cooperativity, and order were approximately 20% greater for TLHSCT; and 3) compared with Mn and MMGD, MHSCT and TLHSCT contained fewer double bonds. Tear lipids are more ordered than meibum lipids, which could have functional consequences. The human meibum peak height ratio of the CH3/CH2 bands is not a factor related to tear film stability with age or sex. The amount of CH3 moieties relative to CH2 moieties and saturation could contribute to a higher meibum lipid order associated with a younger age, meibomian gland dysfunction, and dry eye from hematopoietic stem cell transplantation. Therefore, the hydrocarbon order may be a marker of or contribute to an unstable tear film layer.

Classification of iron oxide aerosols by a single particle soot photometer using supervised machine learning

Abstract. Single particle soot photometers (SP2) use laser-induced incandescence to detect aerosols on a single particle basis. SP2s that have been modified to provide greater spectral contrast between their narrow and broad-band incandescent detectors have previously been used to characterize both refractory black carbon (rBC) and light-absorbing metallic aerosols, including iron oxides (FeOx). However, single particles cannot be unambiguously identified from their incandescent peak height (a function of particle mass) and color ratio (a measure of blackbody temperature) alone. Machine learning offers a promising approach for improving the classification of these aerosols. Here we explore the advantages and limitations of classifying single particle signals obtained with a modified SP2 using a supervised machine learning algorithm. Laboratory samples of different aerosols that incandesce in the SP2 (fullerene soot, mineral dust, volcanic ash, coal fly ash, Fe2O3, and Fe3O4) were used to train a random forest algorithm. The trained algorithm was then applied to test data sets of laboratory samples and atmospheric aerosols. This method provides a systematic approach for classifying incandescent aerosols by providing a score, or conditional probability, that a particle is likely to belong to a particular aerosol class (rBC, FeOx, etc.) given its observed single particle features. We consider two alternative approaches for identifying aerosols in mixed populations based on their single particle SP2 response: one with specific class labels for each species sampled, and one with three broader classes (rBC, anthropogenic FeOx, and dust-like) for particles with similar SP2 responses. Predictions of the most likely particle class (the one with the highest mean probability) based on applying the trained random forest algorithm to the single particle features for test data sets comprising examples of each class are compared with the true class for those particles to estimate generalization performance. While the specific class approach performed well for rBC and Fe3O4 (≥99 % of these aerosols are correctly identified), its classification of other aerosol types is significantly worse (only 47 %–66 % of other particles are correctly identified). Using the broader class approach, we find a classification accuracy of 99 % for FeOx samples measured in the laboratory. The method allows for classification of FeOx as anthropogenic or dust-like for aerosols with effective spherical diameters from 170 to >1200 nm. The misidentification of both dust-like aerosols and rBC as anthropogenic FeOx is small, with <3 % of the dust-like aerosols and <0.1 % of rBC misidentified as FeOx for the broader class case. When applying this method to atmospheric observations taken in Boulder, CO, a clear mode consistent with FeOx was observed, distinct from dust-like aerosols.

Fourier transform infrared microspectroscopic characterization of Neoproterozoic organic microfossils from the Fifteenmile Group in Yukon, Canada

AbstractConventional and synchrotron radiation‐based (SR) Fourier transform infrared microspectroscopies (micro‐FTIR) were applied to four types of ~ 810 Ma organic‐walled microfossils together with diffuse organic matter (OM) and one irregularly shaped structure from the Fifteenmile Group, in Yukon, Canada, for their chemical characterization. The microfossils comprised one filamentous type and three coccoidal types. Micro‐FTIR mapping analysis revealed the micrometer‐scale, spatial distribution of organic components (aliphatic C‐H bonds) and carbonate in the microfossils. Based on comparisons of CH3/CH2 peak height ratios (R3/2) and morphologies of the microfossils (without the diffuse OM) to those of previously described Proterozoic microfossils, possible affinities of the microfossils are suggested, as follows. Palaeolyngbya? and Glenobotrydion belong to bacteria. Myxococcoides is not clearly characterized due to the significant mixing with diffuse OM containing abundant aliphatic C‐H groups. The irregularly shaped structure may represent a eukaryote. The diffuse OM may represent a mixture of decomposed microbial cells and extracellular polymeric substances (EPS). SR micro‐FTIR measurements of two coccoid types (Glenobotrydion and Unnamed Coccoid Form D) revealed that the R3/2 values of the internal spots with wall structures are similar to those without wall structures in Glenobotrydion: those values from Unnamed Coccoid Form D were different. The results suggest that these two coccoids are different chemically as well as morphologically. Micro‐FTIR characterization of the organic‐walled microfossils together with morphological analysis provides new insight into their biological affinities.

Characterisation, verification and genetic basis of anomalous STR patterns: a report of four cases of X-chromosome STR biallelic patterns in human males.

Analysis of the characteristics and genetic basis of the anomalous short tandem repeat (STR) pattern encountered in forensic cases has been shown to be useful for analysing STR profiles in routine forensic casework. Here, we report biallelic patterns at several X-chromosome STR (X-STR) loci in human males revealed by forensic parameters investigation using the commercial AGCU X19 Kit. The presence of these patterns was verified by reanalysis using new samples and bidirectional Sanger sequencing of the singleplex polymerase chain reaction (PCR) products. And the genetic basis for their production was inferred based on the relative peak heights at the amelogenin locus and the affected locus (DXS10159, DXS10134 and DXS10079) and the normalised peak height ratios between the affected locus and adjacent loci relative to the control sample 9947A. The inference results suggested that two cases of biallelic pattern at the DXS10159 locus would be caused by local duplications, while in the other two cases, both the biallelic patterns at loci DXS10134 and DXS10079 would be due to somatic mutations. One case where the male showed a biallelic pattern at the DXS10159 locus (Xp11.21) was further analysed. Quantitative PCR (qPCR) revealed a microduplication (< 0.2Mb) spanning at least 13.9 kb in Xp11.21 encompassing the DXS10159 locus. Finally, a workflow for analysing anomalous STR patterns was summarised. In conclusion, this study is a detailed report of X-STR biallelic patterns in human males, which serves as an effective complement to the database and provides an example for the analysis of anomalous STR patterns.

Classification of the likelihood of colon cancer with machine learning techniquesusing FTIR signals obtained from plasma

Colon cancer is one of the major causes of human mortality worldwide and the same can be said for Turkey. Various methods are used for the determination of cancer. One of these methods is Fourier transform infrared (FTIR) spectroscopy, which has the ability to reveal biochemical changes. The most common features used to distinguish patients with cancer and healthy subjects are peak densities, peak height ratios, and peak area ratios. The greatest challenge of studies conducted to distinguish cancer patients from healthy subjects using FTIR signals is that the signals of cancer patients and healthy subjects are similar. In the current study, a method in which the area and height ratios of the FTIR signal, as well as various statistical features, are proposed in order to overcome this difficulty. Blood samples (plasma) were collected from 30 colon cancer patients and 40 healthy subjects, and FTIR measurements were performed. A total of 16 features were obtained, including five height ratios, five area ratios, and six statistical features, from each FTIR signal. The 16 features were classified with a multilayer perceptron neural network and support vector machines using cross-validation and their performances were then compared. The current study demonstrated that different features obtained from plasma FTIR spectra can be used together in order to distinguish colon cancer patients from healthy individuals.

Mixture deconvolution by massively parallel sequencing of microhaplotypes

Short tandem repeat polymorphisms (STRs) are the standard markers for forensic human identification. STRs are highly polymorphic loci analyzed using a direct PCR-to-CE (capillary electrophoresis) approach. However, STRs have limitations particularly when dealing with complex mixtures. These include slippage of the polymerase during amplification causing stutter fragments that can be indistinguishable from minor contributor alleles, preferential amplification of shorter alleles, and limited number of loci that can be effectively co-amplified with CE. Massively parallel sequencing (MPS), by enabling a higher level of multiplexing and actual sequencing of the DNA, provides forensic practitioners an increased power of discrimination offered by the sequence of STR alleles and access to new sequence-based markers. Microhaplotypes (i.e., microhaps or MHs) are emerging multi-allelic loci of two or more SNPs within < 300bp that are highly polymorphic, have alleles all of the same length, and do not generate stutter fragments. The growing number of loci described in the literature along with initial mixture investigations supports the potential for microhaps to aid in mixture interpretation and the purpose of this study was to demonstrate that practically. A panel of 36 microhaplotypes, selected from a set of over 130 loci, was tested with the Ion S5™ MPS platform (Thermo Fisher Scientific) on single-source samples, synthetic two-to-six person mixtures at different concentrations/contributor ratios, and on crime scene-like samples. The panel was tested both in multiplex with STRs and SNPs and individually. The analysis of single-source samples showed that the allele coverage ratio across all loci was 0.88 ± 0.08 which is in line with the peak height ratio of STR alleles in CE. In mixture studies, results showed that the input DNA can be much higher than with conventional CE, without the risk of oversaturating the detection system, enabling an increased sensitivity for the minor contributor in imbalanced mixtures with abundant amounts of DNA. Furthermore, the absence of stutter fragments simplifies the interpretation. On casework-like samples, MPS of MHs enabled the detection of a higher number of alleles from minor donors than MPS and CE of STRs. These results demonstrated that MPS of microhaplotypes can complement STRs and enhance human identification practices when dealing with complex imbalanced mixtures.

Dynamic susceptibility contrast parametric imaging using accelerated dual-contrast echo planar imaging with keyhole.

Echo planar imaging (EPI) is one of the methods of choice in dynamic susceptibility contrast MRI (DSC-MRI) because it provides a sufficient temporal resolution. However, the relatively long readout duration of EPI often imposes limitations on increased spatial coverage or the use of multiple contrasts. To develop a DSC-MRI method using EPIK (EPI with keyhole) to provide dual-contrast (TE1 and TE2 ) information with a higher spatial coverage than EPI. To compare results from the community-standard EPI method and the proposed EPIK method. Prospective. One healthy subject and 17 brain tumor patients. 3 T/accelerated EPI and dual-contrast EPIK sequences. After an initial evaluation using healthy in vivo images, the use of the proposed method for DSC-MRI was verified with brain tumor patients. The parametric images (eg, CBF and CBV) and arterial input function (AIF), obtained from both the EPI and EPIK, were compared. The ratio of AIF peak height of the proposed method to that of EPI was computed. The ratio computation was also performed for the time-to-peak (TTP) in the AIF curves. From the obtained CBF and CBV maps, the tumor-to-brain (TBR) ratio was also calculated for each imaging method and the results were compared. For the same temporal resolution (1.5 sec), EPIK yielded dual-contrast (TEs of 13/33 msec) with an increased spatial coverage (24 slices) and less geometric distortions than EPI; EPI provided single contrast (TE of 32 msec) with 20 slices. The obtained parametric values (eg, AIF peak, TTP, and TBR) had similar characteristics between EPI and the proposed method. The dual-contrast data produced by EPIK in DSC-MRI allowed T1 -corrected parametric images without the need of second contrast injection and an enhanced estimation of the AIF. 1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;50:628-640.

The transiogram as a graphic metric for characterizing the spatial patterns of landscapes

Landscape metrics play an important role in measurement, analysis, and interpretation of spatial patterns of landscapes. There are a variety of different landscape metrics widely used in landscape ecology. However, existing landscape metrics are mostly non-graphic and single-value indices, which may not be sufficient to describe the complex spatial correlation and interclass relationships of various landscapes. As a transition probability diagram over the lag distance, the transiogram, which emerged in recent years, essentially provides a new graphic metric for measuring and visualizing the auto and cross correlations of landscape categories. To explore the capability of the transiogram for measuring spatial patterns of categorical landscape maps and compare it with existing landscape metrics. Sixteen commonly-used landscape metrics and transiograms (including auto- and cross-transiograms) were estimated and compared for land cover/use classes in four areas with different landscapes. Results show that (1) these transiograms can provide visual information about the proportions, aggregation levels, interclass adjacencies, and intra-class/interclass correlation ranges of landscape classes; (2) sills and auto-correlation ranges of transiograms are correlated with the values of some landscape metrics; and (3) the peak height ratios of idealized transiograms can effectively represent the juxtaposition strength of neighboring class pairs. The transiogram can be an effective graphic metric for characterizing the auto-correlation of single classes (through auto-transiograms) and the complex interclass relationships, such as interdependency and juxtaposition, between different landscape classes (through cross-transiograms).

Improving Photoplethysmographic Measurements Under Motion Artifacts Using Artificial Neural Network for Personal Healthcare

Photoplethysmographic (PPG) measurements are susceptible to motion artifacts (MA) due to movement of the peripheral body parts. In this paper, we present a new approach to identify the MA corrupted PPG beats and then rectify the beat morphology using artificial neural network (ANN). Initially, beat quality assessment was done to identify the clean PPG beats by a pre-trained feedback ANN to generate a reference beat template for each person. The PPG data was decomposed using principal component analysis (PCA) and reconstructed using fixed energy retention. A weight coefficient was assigned for each PPG samples in such a way that when they are multiplied , the modified beat morphology matches the reference template. A particle swarm optimization (PSO) based technique was utilized to select the best weight weight vector coefficients to tune another feedback ANN, fed with a set of significant features generated by an auto encoder from PCA reconstructed data. For real time implementation, this pre-trained ANN was operated in feed-forward mode to directly generate the weight vectors for any subsequent measurements of PPG. The method was validated with PPG data collected from 55 human subjects. An average RMSE of 0.28 and SNR improvement of 14.54 dB was obtained, with an average improvement of 36% and 47% measurement accuracy on crest time and systolic to diastolic peak height ratio respectively. With IEEE Signal Processing Cup 2015 Challenge database, Pearson's correlation coefficient between PPG estimated and ECG derived heart rate was 0.990. The proposed method can be useful for personal health monitoring applications.

Assessing UO2 sample quality with μ-Raman spectroscopy

μ-Raman spectroscopy of UO2 has demonstrated its value as a tool in nuclear forensics and for analyzing nuclear fuels, but its ability to evaluate UO2 sample quality has been relatively unexplored. To investigate this potential, a three-pronged study that uses Raman spectroscopy to analyze 1) three distinct qualities of UO2 single crystals with two different excitation lasers, 2) a high quality single crystal UO2 sample that is progressively damaged with a laser, and 3) a single crystal of UO2 grown on top of a ThO2 substrate was undertaken. The results demonstrate that the peak height ratio between the second order longitudinal optical phonon signal near 1145 cm−1 and the T2g peak located near 450 cm−1 is directly correlated with crystal quality when a 532 nm excitation source is used. Furthermore, this observed pattern relies upon the two most intense peaks that are present in the Raman spectra, making it more robust to lower signal-to-noise ratios than similar trends present in the peak height ratio between the first order longitudinal optical phonon signal near 565 cm−1 and the T2g peak. Both peak height ratios are more sensitive indicators of the crystal quality than the width ratios of the same signals or the associated wavenumber shift in the T2g peak location. The correlation between the 2LO and T2g peak heights and the overall crystal quality offers the potential to directly assess and compare the quality of different samples of single crystal UO2.

Screening and quantitation of forty-six drugs of abuse and toxic compounds in human whole blood by capillary electrophoresis: Application to forensic cases

A novel capillary electrophoresis method, coupled with photo-diode array detection, was established for the analysis of forty-six drugs of abuse, including opiates, cocaine, amphetamines, benzodiazepines, and alkaloids, in human whole blood. Doxapram was used as the internal standard, and an Oasis HLB column was used for solid-phase extraction of drugs from human whole blood. This method was applied to analyze real blood samples in forensic cases. The separation was performed on a fused-silica capillary (75 μm I.D. × 50.2 cm, with 40 cm of effect length). In this study, the running buffer was 150 mM phosphate buffer (pH 2.4) containing 20% methanol. Samples were injected at a pressure of 0.5 psi for 10 s and separated at a running voltage of 16 kV. The precision, accuracy, sensitivity, linear range, limit of detection, and recovery of the method were evaluated. The time taken for the entire separation process was 18.5 min. All compounds were identified by relative retention times, and the peak height ratios (the ratio between the target analyte peak height and the internal standard peak height) were monitored at 200 nm and 210 nm in corresponding ultraviolet spectra. 210 nm was used as quantitative detection wavelength. Calibration curves were established for all compounds of interest. For human blood samples, the detection limits were 8–80 ng/mL, and the linear range was 0.03–10 μg/mL. The intraday and interday precisions were both less than 13%. This method offers simple and effective screening and quantitation of drugs of abuse and toxic compounds in human blood at toxicologically relevant concentrations, and was applied to analyze blood samples from forensic cases.

Measuring Perchlorate and Sulfate in Planetary Brines Using Raman Spectroscopy

Liquid water likely exists on the surface of Mars and below the icy crusts of Europa, Enceladus, and Titan. Pluto, Ceres, and Ganymede also show evidence of liquid water at or near the surface. Quantitative solute analyses would provide critical data needed to understand geochemical conditions throughout our solar system, including potential habitability of planetary bodies. We have developed and tested a Raman spectroscopic method for measuring perchlorate and sulfate in brines and dilute waters that utilizes simple Raman peak height ratios rather than peak area ratios. Ratios of the target anion and OH- bending water peaks yield linear fits with positive slopes and r2 values >0.99. Calibration fits for each solute–brine combination and ultrapure water yield similar linear equations, suggesting this method can detect and quantitatively measure solutes in complex aqueous solutions. No sample preparation or physical contact with the sample is required. Therefore, this method can be employed without contami...

The CANDELLE Experiment for Characterization of Neutron Sensitivity of LiF TLDs

As part of the design studies of future power and research nuclear reactors, the validation of neutron and photon calculation schemes requires the implementation of nuclear heating measurements. Such measurements are usually performed in very low-power reactors, whose core dimensions are accurately known and where irradiation conditions are entirely controlled. The use of thermoluminescent dosimeters is particularly well suited to gamma heating measurements, although the TLDs are also sensitive to neutrons depending on their composition. Hence, for gamma heating assessment in a mixed gamma–neutron field, the neutron sensitivity correction factors of TLDs has to be accurately determined to ensure a better interpretation of doses measured in a reactor with reduced uncertainties. This paper presents the CANDELLE experiment, which is dedicated to the implementation of a pure neutron field calibration of lithium-enriched TLDs, by using the Platform for Studies and Research on Nuclear Energy platform of LPSC. This calibration step is part of a promising approach that has been recently developed at INFN for medical purposes, aiming at determining the gamma and neutron contributions to the doses measured by LiF TLDs in the mixed field, from the peak height ratios of the gamma and neutron calibration glow curves of this type of TLDs. The test irradiations conducted at LPSC within the first phase of the CANDELLE project allowed retrieving the peak height of LiF TLDs in fast neutron field, hence providing an early assessment of the neutron components of doses measured in the EOLE reactor at CEA Cadarache with around 10% uncertainty at $1\sigma$ . From these preliminary results, the second phase of the project will be devoted, on the one hand, to the use of moderator screens aiming at achieving a thermal neutron field while avoiding a too strong attenuation of the flux, and on the other hand, to the determination of the neutron spectrum at different locations within the irradiation area.

Ratios and distances of pull-up peaks observed in GlobalFiler kit data.

Short tandem repeat (STR) analysis is widely used for forensic examinations with a capillary electrophoresis instrument such as the 3500xL Genetic Analyzer. This instrument adapts multi-locus STR kits to examine up to 27 loci using a 6-fluorescent dye system and corrects the spectral overlap between each dye. However, inaccurate spectral correction can cause pull-up peaks. Here, we examined the pull-up peaks observed in GlobalFiler kit data in terms of their peak height ratios and distances from their parent allele peaks when using the 3500xL and the 3130xl Genetic Analyzers. With the 3500xL, 546 pull-up peaks were observed, and their pull-up ratios averaged 1.03 ± 0.32% (range 0.260-2.80%). Of the 546 pull-up peaks, 534 peaks (97.8%) were within ±1 bp from their parent allele peaks. Overall, the pull-up peaks toward adjacent shorter wavelength channels (e.g., from yellow to green) tended to be observed in the left side (shorter bp) of the corresponding parent allele peaks, and the opposite side tendency was observed for those pull-up peaks toward adjacent longer wavelength channels. These tendencies were also observed in the GlobalFiler data generated with the 3130xl and in the data obtained by injecting a J6 matrix standard with LIZ 500 or 600 v2 size standard into the 3500xL and 3130xl. Inspection of raw data revealed that the shift of pull-up peaks from their parent allele peaks was derived from sigmoid, pull-down, or slightly shifted pull-up shapes. Based on the obtained data, we propose a standard for assessment of questionable pull-up peaks.

A method to reveal bulk and surface crystallinity of Polypropylene by FTIR spectroscopy - Suitable for fibers and nonwovens

The crystallinity of polymers is usually determined via Differential Scanning Calorimetry (DSC), X-ray diffraction (XRD) or density measurements. Even though DSC is an easy and fast way to determine crystallinity, it suffers of several disadvantages in the case of fibers and nonwovens. In DSC studies, the sample preparation of fiber material may be difficult, results are not calibration free and heat is introduced in the measuring process, which might lead to transitions in instable crystal structures in the polymer. XRD is able to overcome these problems but is also time consuming and complicated in terms of sample preparation and evaluation of the measurements. Furthermore, it is not possible to determine surface crystallinity or crystallinity gradients inside the specimen with both methods.Based on approaches found in literature, a method was developed which is capable of measuring the degree of crystallinity in the bulk and at the surface of Polypropylene via Fourier transformed infrared spectroscopy. A broad set of calibration samples with a wide range of degrees of crystallinity but without a crystallinity gradient was produced by cooling samples with cooling rates from 1 to 3500 K min−1. The degree of crystallinity was then determined from the ratio of the maximum peak height at 974 cm−1 and the maximum peak height at 998 cm−1 multiplied by 61.4%.Consecutively, the transferability of the method to the measurement of fibers and nonwovens is demonstrated and verified via procedures which are already well described in literature. This method has an excellent reproducibility, spatial resolution and is capable of determining the degree of crystallinity in less than 5 min. Furthermore, this method is easy to implement and does not require further sample preparation.

Changes of aliphatic C-H bonds in cyanobacteria during experimental thermal maturation in the presence or absence of silica as evaluated by FTIR microspectroscopy.

Aliphatic C-H bonds are one of the major organic signatures detected in Proterozoic organic microfossils, and their origin is a topic of interest. To investigate the influence of the presence of silica on the thermal alteration of aliphatic C-H bonds in prokaryotic cells during diagenesis, cyanobacteria Synechocystis sp. PCC6803 were heated at temperatures of 250-450°C. Changes in the infrared (IR) signals were monitored by micro-Fourier transform infrared (FTIR) spectroscopy. Micro-FTIR shows that absorbances at 2,925cm-1 band (aliphatic CH2 ) and 2,960cm-1 band (aliphatic CH3 ) decrease during heating, indicating loss of the C-H bonds, which was delayed by the presence of silica. A theoretical approach using solid-state kinetics indicates that the most probable process for the aliphatic C-H decrease is three-dimensional diffusion of alteration products under both non-embedded and silica-embedded conditions. The extrapolation of the experimental results obtained at 250-450°C to lower temperatures implies that the rate constant for CH3 (kCH3 ) is similar to or lower than that for CH2 (kCH2 ; i.e., CH3 decreases at a similar rate or more slowly than CH2 ). The peak height ratio of 2,960cm-1 band (CH3 )/2,925cm-1 band (CH2 ; R3/2 values) either increased or remained constant during the heating. These results reveal that the presence of silica does affect the decreasing rate of the aliphatic C-H bonds in cyanobacteria during thermal maturation, but that it does not significantly decrease the R3/2 values. Meanwhile, studies of microfossils suggest that the R3/2 values of Proterozoic prokaryotic fossils from the Bitter Springs Group and Gunflint Formation have decreased during fossilization, which is inconsistent with the prediction from our experimental results that R3/2 values did not decrease after silicification. Some process other than thermal degradation, possibly preservation of specific classes of biomolecules with low R3/2 values, might have occurred during fossilization.