Replicate Measurements Research Articles

Electrochemically deposition of ionic liquid modified graphene oxide for circulated headspace in-tube solid phase microextraction of naphthalene from honey samples followed by on-line liquid chromatography analysis.

In this work, an inexpensive, fast, and selective ionic liquid modified graphene oxide (GO-IL) was synthesized and electrochemically deposited on the inner surface of a stainless-steel tube. Then, it was applied for circulated headspace in-tube solid-phase microextraction (CHS-IT-SPME) of naphthalene from honey samples. Next, the coated tube was replaced with the sample loop of a six-port injection valve for on-line desorption and further HPLC-UV analysis of naphthalene. The sorbent was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), and energy-dispersive X-ray spectroscopy (EDX). Different parameters affecting the procedure efficiency, including extraction temperature, extraction time, salt concentration, and sample volume were optimized by central composite design and response surface methodology. Under the optimum conditions, the calibration curve was linear within the range of 0.3-200 ng mL-1, with a regression coefficient of 0.9972. The limits of detection (LOD) and quantification (LOQ) were found to be 0.1 ng mL-1 and 0.3 ng mL-1, respectively. Intra-day and inter-day RSDs% for three replicate measurements of naphthalene at the concentration of 10 ng mL-1 were obtained 3.9% and 5.0%, respectively. Also, good tube-to-tube reproducibility of 5.3% was achieved. Finally, the method was successfully applied for measuring trace amounts of naphthalene in honey samples. Relative recoveries were calculated within the range of 90.0-106.5%, indicating excellent efficiency of the proposed method.

Two-step separation and determination of inorganic As species in water, soil and sediment samples by implementing two ionic liquids in dispersive liquid–liquid microextraction with electrothermal atomic absorption spectrometry detection

A highly efficient liquid–liquid microextraction method based on two magnetic ionic liquids (MILs) as extraction solvents for the determination of inorganic As species in water, soil and sediment samples, with electrothermal atomic absorption spectrometry detection, was developed. First, As(III) species was separated by chelation with ammonium pyrrolidine dithiocarbamate and then extracted by the MIL trihexyl(tetradecyl)phosphonium hexachlorodisprosiate ([P6,6,6,14]3DyCl6). The As(V) species remaining in the aqueous phase was preconcentrated by extraction in the MIL trihexyl(tetradecyl)phosphonium tetrachloroferrate ([P6,6,6,14]FeCl4) at 2 mol L-1 HCl. The MIL phase containing As(V) was separated by a magnetic rod and diluted in chloroform. Then, an aliquot was injected into the graphite furnace for As determination. Total inorganic As was determined using the MIL [P6,6,6,14]FeCl4 as the extraction solvent at 0.5 mol L-1 HCl to achieve the same extraction efficiency for both species. The concentration of As(III) was calculated by the difference between total inorganic As and As(V) concentration. An extraction efficiency of 99% for As(V) and an enhancement factor of 35 were obtained with 5 mL of sample. The method detection limits were 17 ng L-1, 0.11 ng g−1 and 0.13 ng g−1 for As(V) and 20 ng L-1, 0.13 ng g−1 and 0.14 ng g−1 for As(III) in water, soil and sediment samples, respectively. The relative standard deviations for six replicate measurements of 3 µg L-1 for As(V) and As(III) were 3.1% and 3.9% respectively. The calibration linear range was 0.05–13 µg L-1. The method was successfully applied for inorganic As species determination in water, soil and sediment samples.

The Sexual and Reproductive Health Burden Index: Development, Validity, and Community-Level Analyses of a Composite Spatial Measure.

The Sexual and Reproductive Health Burden Index (SRHBI) was developed to provide a composite spatial measure of sexual and reproductive health (SRH) indicators that can be widely adopted by urban public health departments for the planning of SRH services. The index was constructed using eight indicators: teen births, low birthweight, infant mortality, new HIV diagnoses, people living with HIV, and incidences of gonorrhea, chlamydia, and syphilis. Chicago Department of Public Health data (2014-2017) were used to calculate index scores for Chicago community areas; scores were mapped to provide geovisualization and global Moran's I was calculated to assess spatial autocorrelation. Cronbach's alpha was calculated to assess internal reliability of the SRHBI. Pearson correlations were conducted to assess concurrent validity and correlation with community-level factors. Linear regression was conducted to assess community-level predictors of the SRHBI. Application of the SRHBI in Chicago demonstrates substantial variation in SRH burden across Chicago's urban landscape with significant spatial autocorrelation of scores (I = .580, p = .001). Internal reliability of the measure was excellent with α = .937. The SRHBI was significantly correlated with other indicators of SRH including rate of prenatal care initiation in the first trimester, rate of preterm births, reported sexual assault incidence, cervical cancer incidence, prostate cancer incidence, and rate of smoking during pregnancy. This suggests good concurrent validity of the measure. Linear regression revealed that the percent of Black residents, percent of household couples that are same-sex, community violence, economic hardship, and population density were significant predictors of the SRHBI. The SRHBI provides a valid, useful, and replicable measure to assess and communicate community-level SRH burden in urban environments. The SRHBI may be scaled through a multi-city public data dashboard and utilized by urban public health departments to optimally target and tailor SRH interventions to communities.

Rethinking hyperactivity in pediatric ADHD: Preliminary evidence for a reconceptualization of hyperactivity/impulsivity from the perspective of informant perceptual processes.

Hyperactivity is a core ADHD symptom that has been both positively and negatively associated with cognition and functional outcomes. The reason for these conflicting findings is unclear but may relate to subjective assessments that conflate excess physical movement (hyperactivity) with verbally intrusive/impulsive behaviors. The current study adopted a model-driven, rational-empirical approach to distinguish excess physical movement symptoms from other, auditorily perceived behaviors assessed under the "hyperactivity/impulsivity" umbrella. We then tested this alternative conceptualization's fit, reliability, replicability, convergent/divergent validity via actigraphy, and generalizability across informants (parents, teachers) in a well-characterized, clinically evaluated sample of 132 children ages 8-13 years (M = 10.34, SD = 1.51; 47 girls; 67% White/non-Hispanic). The current DSM hyperactivity/impulsivity item pool can be reliably reclassified by knowledgeable judges into items reflecting excess physical movement (visual hyperactivity) and auditory interruptions (verbal intrusion). This bifactor structure showed evidence for multidimensionality and superior model fit relative to traditional hyperactivity/impulsivity models. The resultant visual hyperactivity factor was reliable, replicable, and showed strong convergent validity evidence via associations with objectively assessed hyperactivity. The verbal intrusion factor also showed evidence for reliability and explained a substantive portion of reliable variance, but demonstrated lower estimated replicability. These findings provide preliminary support for conceptualizing ADHD symptoms from the perspective of their cognitive-perceptual impact on others, as well as differentiating excess physical movement (hyperactivity) from other behaviors assessed under the hyperactivity/impulsivity umbrella. "Verbal intrusion" appears to provide a better explanation than "impulsivity" for the reliable, non-hyperactivity variance assessed by these items, but the current item set appears insufficient for replicable measurement of this construct. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Correction: Quantification of glucose-6-phosphate dehydrogenase activity by spectrophotometry: A systematic review and meta-analysis.

[This corrects the article DOI: 10.1371/journal.pmed.1003084.].

Determination of Gemfibrozil in Drug Matrix and Human Biological Fluid by Dispersive Liquid-Liquid Microextraction with High Performance Liquid Chromatography

A simple and rapid dispersive liquid-liquid microextraction technique coupled with high performance liquid chromatography (HPLC) was developed for the extraction and analysis of gemfibrozil in drug matrix and biological fluids like human plasma and urine samples. In this method, carbon tetrachloride at microliter volume level and methanol were used as extraction and disperser solvents, respectively. The effects of factors including the type and volume of disperser and extraction solvents, pH and extraction time on the performance of the sample preparation were carefully evaluated. Under optimum conditions, the obtained enrichment factors were between 9.2 - 9.3 and extraction recoveries were high and ranged between 91.2 - 93.2%. The calibration curve was linear in the range of 0.1 - 100 mg/L with a detection limit of 12.3 µg/L. The relative standard deviation (RSD) for ten replicate measurements of gemfibrozil was 1.3%. The performance of the method was checked by the analysis of the gemfibrozil in presence of other drugs in water samples.

Simultaneous Separation of Sb(III) and Sb(V) by High Performance Liquid Chromatography (HPLC) – Inductively Coupled Plasma – Mass Spectrometry (ICP-MS) with Application to Plants, Soils, and Sediments

The simultaneous separation and determination of inorganic trivalent antimony Sb(III) and pentavalent antimony Sb(V) in plant, soil, and sediment samples was carried out by high performance liquid chromatography – inductively coupled plasma – mass spectrometry (HPLC-ICP-MS). The chromatographic conditions (composition and concentration of competing ion, pH value and flow rate of mobile phase) and the operating parameters for inductively coupled plasma – mass spectrometry were optimized by single factor experiments. The separation of the Sb species was achieved within 6 min using the optimized chromatographic conditions. The detection limits of the method were 0.016 μg/L and 0.021 μg/L for Sb(III) and Sb(V), respectively. The retention times of Sb(V) and Sb(III) were 2.7 min and 4.5 min, respectively. The relative standard deviations for replicate measurements (n = 6) of low (5 μg/L), medium (20 μg/L), and high (40 μg/L) concentrations of Sb(III) and Sb(V) were less than 4%. The results of spiking and recovery experiments for the extracting solutions of soil, sediments, and plants showed that the spiked recoveries of the two species ranged from 92% to 103%. This method has been used to determine the antimony species in extracts of environmental samples.

Nature inspired poly (dopamine quinone -vanadyl) as new modifier for voltammetric determination of uric acid.

Thepreparation of a novel polymer (poly(dopamine quinone-vanadyl) (polyDQV)) bearing dopaminequinone and VOIV redox groupsis described. PolyDQV was characterized using field emission scanning electron microscopy (FESEM), energy dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy (XPS), Fourier transform infra-red (FTIR) spectroscopy, UV-Vis spectroscopy as well as electrochemical methods such as differential pulse voltammetry, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). The electrocatalytic activity of polyDQV was studied toward electrooxidation of uric acid using differential pulse voltammetry as well as cyclic voltammetry. PolyDQV presents interesting electrocatalytic activity toward UA oxidation in phosphate buffer solution (0.1M, pH2) to a well-defined oxidation peak at 0.65V (vs. Ag/AgCl). The polyDQV-modified carbon paste electrode (CPE/polyDQV) presents a precise linear signal-concentration relationship in the ranges of 0.3-5μM and 5 to 200μM with a detection limit (S/N = 3) of 0.02μM. The %RSD values for ten replicate measurements of 0.5 and 50μM UA were 1.8 and 3%, respectively, indicating good repeatability of analytical signals. Appropriate recovery values (in the range 96 to 103%) and good selectivity for UA over common coexisting species (such as ascorbic acid and dopamine) exhibit that CPE/polyDQV is a promising novel platform for sensing UA in human blood serum and urine samples. Graphical abstract.

Intra-laboratory assessment of a method for the detection of TiO2 nanoparticles present in sunscreens based on multi-detector asymmetrical flow field-flow fractionation

In this study, an intra-laboratory assessment was carried out to establish the effectiveness of a method for the detection of TiO2 engineered nanoparticles (ENPs) present in sunscreen containing nano-scale TiO2 and a higher nanometer-range (approx. 200–500 nm) TiO2, as well as iron oxide particles. Three replicate measurements were performed on five separate days to generate the measurement uncertainties associated with the quantitative asymmetrical flow field-flow fractionation (AF4) measurement of the hydrodynamic radius rh,mode1 (MALS), rh,mode1 (ICP-MS), rh,mode2 (ICP-MS), and calculated mass-based particle size distribution (d10, d50, d90). The validation study demonstrates that the analysis of TiO2 ENPs present in sunscreen by AF4 separation-multi detection produces quantitative data (mass-based particle size distribution) after applying the sample preparation method developed within the NanoDefine project with uncertainties based on the precision (uIP) of 3.9–8.8%. This method can, therefore, be considered as the method with a good precision. Finally, the bias data shows that the trueness of the method (ut = 5.5–52%) can only be taken as a proxy due to the lack of a sunscreen standard containing certified TiO2 ENPs.

Accurate and simple determination of oxcarbazepine in human plasma and urine samples using switchable-hydrophilicity solvent in GC-MS.

This work presents a sensitive and rapid analytical method for the determination of oxcarbazepine in human plasma and urine samples. A vortex-assisted switchable hydrophilicity solvent-based liquid phase microextraction (VA-SHS-LPME) was used to preconcentrate oxcarbazepine from the samples before the determination by gas chromatography mass spectrometry. The switchable hydrophilicity solvent was synthesized by protonating N,N-dimethylbenzylamine with carbon dioxide to make it totally miscible with an equivalent volume of water. Parameters of the VA-SHS-LPME method including volume of switchable hydrophilicity solvent, concentration/volume of sodium hydroxide and vortex period were systematically optimized. Under the optimum conditions, good linearity ranging from 27.03 to 353.47 μg/kg was obtained for the analyte. Limit of detection and quantitation values were found to be 6.2 and 21 μg/kg (mass base), respectively. The relative standard deviation was calculated as 6.9% for six replicate measurements of the lowest concentration of the calibration plot. Satisfactory recovery results were calculated in the range of 97-100% for human plasma and urine samples spiked at five different concentrations.

Spiking and homogenization of biological matrices for production of reference materials using cryogenic processes.

Biological reference materials (RMs) are essential for quality assurance, traceability of measurement results and for method validation. When addressing new measurement questions or emerging regulatory issues, rigorous large-scale CRM production may not be time efficient or economically practical using current production methods. By amending a relatively small matrix batch with a compound(s) of interest at the homogenization step, the National Institute of Standards and Technology (NIST) can create a custom material on an "as-needed" basis and circumvent the time delay inherent in large-batch production, thereby generating a fit-for-purpose, rapid-response RM. Here, Coho salmon (Oncorhynchus kisutch) was cryohomogenized and spiked with an aquaculture antibiotic and antibiotic metabolite. The resultant material was analyzed using liquid chromatography-high resolution tandem mass spectrometry (LC-HRMS/MS) to determine the effectiveness of the amendment technique in a fresh-frozen matrix by assessing homogeneity and accuracy to the target concentration (e.g. mass fraction). Target mass fractions were achieved for both spike components, with RSDs below 5% in replicate measurements of each compound (n = 8). The stability of the spiked compounds was assessed oneyear post-production and mass fractions were stable, within 1-6% of the initial measurement results, indicating minimal change to the amended analyte concentrations over time. The results support this method as a promising new technique for custom, small-batch RM generation.

Disruption of oligodendrocyte progenitor cells is an early sign of pathology in the triple transgenic mouse model of Alzheimer's disease

There is increasing evidence that myelin disruption is related to cognitive decline in Alzheimer's disease (AD). In the CNS, myelin is produced by oligodendrocytes, which are generated throughout life by adult oligodendrocyte progenitor cells (OPCs), also known as NG2-glia. To address whether alterations in myelination are related to age-dependent changes in OPCs, we analyzed NG2 and myelin basic protein (MBP) immunolabelling in the hippocampus of 3×Tg-AD mice at 6 and 24 months of age, compared with non-Tg age-matched controls. There was an age-related decrease in MBP immunostaining and OPC density, together with a decline in the number of OPC sister cells, a measure of OPC replication. Notably, the loss of myelin and OPC sister cells occurred earlier at 6 months in 3xTg-AD, suggesting accelerated aging, although there was not a concomitant decline in OPC numbers at this age, suggesting the observed changes in myelin were not a consequence of replicative exhaustion, but possibly of OPC disruption or senescence. In line with this, a key finding is that compared to age-match controls, OPC displayed marked morphological atrophy at 6 months in 3xTg-AD followed by morphological hypertrophy at 24 months, as deduced from significant changes in total cell surface area, total cell volume, somata volume and branching of main processes. Moreover, we show that hypertrophic OPCs surround and infiltrate amyloid-β (Aβ) plaques, a key pathological hallmark of AD. The results indicate that OPCs undergo complex age-related remodeling in the hippocampus of the 3xTg-AD mouse model. We conclude that OPC disruption is an early pathological sign in AD and is a potential factor in accelerated myelin loss and cognitive decline.

Common institutional design, divergent results: A comparative case study of collaborative governance platforms for regional water planning

Environmental governance challenges often span geographic and sectoral boundaries, requiring collaboration between diverse stakeholders and multilateral decision making. To facilitate such efforts, policymakers and public managers create and support platforms that provide a structured framework for promoting collaborative governance. As the collaborative platform model is often centrally initiated – e.g., when state or national actors create a system of local collaborative resource management platforms – cross-case comparison is particularly important for understanding how a common design leads to variance in procedures and outputs in local contexts. Many collaborative platforms leave a “paper trail” of documents such as meeting records and plans. This analysis compares 10 identically designed and simultaneously initiated regional water planning platforms in the State of Georgia. Drawing on 106 meeting reports, we apply topic modeling to these meeting documents to generate replicable and scalable measures of how participant actions and interest representation unfold over time. Specifically, we measure topical focus on water planning issues over time, and compare these process-phase measures between councils and against the content of the resulting plan developed by each planning council. While existing literature has focused on how institutional design features such as representation and decision-rules shape procedural outcomes and outputs, we observe considerable variation in procedural behavior and plan outputs despite the fact that all 10 platforms share a common design. The consulting firm selected to direct each local platform is shown to be associated with both the topical focus of each regions’ planning discussion and the BMPs selected in regional plans. This comports with recent evidence pointing to the important – and largely overlooked – role that technical consultants play in environmental governance and regulatory processes.

A novel preconcentration/extraction method for fenitrothion residues and its electrochemical sensing in pistachio kernels

The accumulation of organophosphate pesticides (OPPs) in the environment has turned into a predicament for ecological balance and human health. So in this study, a sensitive, easy, and efficient method has been offered for the preconcentration and quantification of the low levels of fenitrothion, one of the prevalent organophosphates, in pistachio kernels. In this technique, at the first step, fenitrothion from aqueous medium was extracted into a few microliters of chloroform using dispersive liquid–liquid microextraction method. After centrifugation and separation of the fenitrothion-containing chloroform drop, it was casted on the surface of a glassy carbon electrode modified with carbon nanotubes. Then, chloroform was allowed to be evaporated at room temperature. Finally, the electrode was immersed into 0.10 M phosphate buffer solution (pH 7.0), where cyclic voltammogram of the deposited fenitrothion was recorded. After optimization of different experimental parameters affecting extraction and electrochemical steps, the concentration linear range of fenitrothion was obtained to be 0.54–6.84 µM. Detection limit was 0.090 µM and the relative standard deviation for seven replicate measurements of the 1.80 µM fenitrothion solution was 3.3%.

AgNP-“Zeolite A”/NG as a Novel Nanocatalyst for Methanol Electro-Oxidation in Alkaline Setting

In this research, the glassy carbon electrode was modified by silver nanoparticles zeolite type A composite, hybridized with the nitrogen-doped graphene (AgNP-“zeolite A”/NG). The electrocatalytic oxidation of methanol was investigated at the surface of the modified electrode in alkaline solution using cyclic voltammetry, chronoamperometry and linear sweep voltammetry methods, and followingly, excellent electrocatalytic activity was observed. The structure and morphology of the resulting AgNP-“zeolite A”/NG were characterized by scanning electron microscopy, dynamic light scattering, X-ray diffraction, Fourier transform infrared spectroscopy and Raman spectroscopy techniques. This electrode was found as a good candidate for application in the anode pole of the direct methanol fuel cell. Silver incorporated in this modified electrode played a key role for oxidation of methanol. The results confirmed the adsorption-controlled reaction at the surface of the modified electrode. Also, the effect of some parameters such as pH, scan rate of potential and the concentration of methanol were explored. Moreover, the kinetic parameters such as transfer coefficient (ko) and exchange current (io) were obtained 1.199 × 10−7 and 2.18 × 10−4 A, respectively, for methanol electro-oxidation process by the AgNP-“zeolite A”/NG. The relative standard deviation of ten replicate measurements, performed on a single electrode in 1.5 × 10−4 M of methanol in alkaline setting, was calculated 2.1% too.

Quantification of glucose-6-phosphate dehydrogenase activity by spectrophotometry: A systematic review and meta-analysis.

The radical cure of Plasmodium vivax and P. ovale requires treatment with primaquine or tafenoquine to clear dormant liver stages. Either drug can induce haemolysis in individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency, necessitating screening. The reference diagnostic method for G6PD activity is ultraviolet (UV) spectrophotometry; however, a universal G6PD activity threshold above which these drugs can be safely administered is not yet defined. Our study aimed to quantify assay-based variation in G6PD spectrophotometry and to explore the diagnostic implications of applying a universal threshold. Individual-level data were pooled from studies that used G6PD spectrophotometry. Studies were identified via PubMed search (25 April 2018) and unpublished contributions from contacted authors (PROSPERO: CRD42019121414). Studies were excluded if they assessed only individuals with known haematological conditions, were family studies, or had insufficient details. Studies of malaria patients were included but analysed separately. Included studies were assessed for risk of bias using an adapted form of the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool. Repeatability and intra- and interlaboratory variability in G6PD activity measurements were compared between studies and pooled across the dataset. A universal threshold for G6PD deficiency was derived, and its diagnostic performance was compared to site-specific thresholds. Study participants (n = 15,811) were aged between 0 and 86 years, and 44.4% (7,083) were women. Median (range) activity of G6PD normal (G6PDn) control samples was 10.0 U/g Hb (6.3-14.0) for the Trinity assay and 8.3 U/g Hb (6.8-15.6) for the Randox assay. G6PD activity distributions varied significantly between studies. For the 13 studies that used the Trinity assay, the adjusted male median (AMM; a standardised metric of 100% G6PD activity) varied from 5.7 to 12.6 U/g Hb (p < 0.001). Assay precision varied between laboratories, as assessed by variance in control measurements (from 0.1 to 1.5 U/g Hb; p < 0.001) and study-wise mean coefficient of variation (CV) of replicate measures (from 1.6% to 14.9%; p < 0.001). A universal threshold of 100% G6PD activity was defined as 9.4 U/g Hb, yielding diagnostic thresholds of 6.6 U/g Hb (70% activity) and 2.8 U/g Hb (30% activity). These thresholds diagnosed individuals with less than 30% G6PD activity with study-wise sensitivity from 89% (95% CI: 81%-94%) to 100% (95% CI: 96%-100%) and specificity from 96% (95% CI: 89%-99%) to 100% (100%-100%). However, when considering intermediate deficiency (<70% G6PD activity), sensitivity fell to a minimum of 64% (95% CI: 52%-75%) and specificity to 35% (95% CI: 24%-46%). Our ability to identify underlying factors associated with study-level heterogeneity was limited by the lack of availability of covariate data and diverse study contexts and methodologies. Our findings indicate that there is substantial variation in G6PD measurements by spectrophotometry between sites. This is likely due to variability in laboratory methods, with possible contribution of unmeasured population factors. While an assay-specific, universal quantitative threshold offers robust diagnosis at the 30% level, inter-study variability impedes performance of universal thresholds at the 70% level. Caution is advised in comparing findings based on absolute G6PD activity measurements across studies. Novel handheld quantitative G6PD diagnostics may allow greater standardisation in the future.

Establishment of a longitudinal pre-clinical model of lyssavirus infection

Traditional mouse models of lyssavirus pathogenesis rely on euthanizing large groups of animals at various time points post-infection, processing infected tissues, and performing histological and molecular analyses to determine anatomical sites of infection. While powerful by some measures, this approach is limited by the inability to monitor disease progression in the same mice over time. In this study, we established a novel non-invasive mouse model of lyssavirus pathogenesis, which consists of longitudinal imaging of a luciferase-expressing Australian bat lyssavirus (ABLV) reporter virus. In vivo bioluminescence imaging (BLI) in mice revealed viral spread from a peripheral site of inoculation into the central nervous system (CNS), with kinetically and spatially distinct foci of replication in the footpad, spinal cord, and hindbrain. Detection of virus within the CNS was associated with onset of clinical disease. Quantification of virus-derived luminescent signal in the brain was found to be a reliable measure of viral replication, when compared to traditional molecular methods. Furthermore, we demonstrate that in vivo imaging of ABLV infection is not restricted to the use of albino strains of mice, but rather strong BLI signal output can be achieved by shaving the hair from the heads and spines of pigmented strains, such as C57BL/6. Overall, our data show that in vivo BLI can be used to rapidly and non-invasively identify sites of lyssavirus replication and to semi-quantitatively determine viral load without the need to sacrifice mice at multiple time points.

Selective determination of Cr(Ⅵ) and non-chromatographic speciation analysis of inorganic chromium by chemical vapor generation-inductively coupled plasma mass spectrometry

A novel and sensitive method for the selective determination of Cr(VI) and non-chromatographic speciation of Cr(VI) and Cr(III) was developed based on chemical vapor generation (CVG) in KBH4-acid system for sample introduction into an inductively coupled plasma mass spectrometer (ICP-MS) for detection. The CVG of Cr(VI), rather than Cr(III), was found to be remarkably enhanced in the presence of sodium diethylaminodithioformate (DDTC). After the oxidation of Cr(III) to Cr(VI) by KMnO4, the quantitation of Cr(III) could be obtained based on the difference between the concentration of total chromium and that of Cr(VI). Parameters affecting the CVG reaction and determination of Cr(VI) were evaluated in detail, including the concentrations of DDTC, hydrochloric acid and KBH4, the sample flow rate, as well as the length of reaction and transferring tubing. Under optimal conditions, the CVG efficiency and the limit of detection (LOD) of Cr(VI) were found to be 28% and 0.2 ng mL−1, respectively. The relative standard deviations for seven replicate measurements of 20 ng mL−1 of Cr(Ⅵ) was 1.8%. Furthermore, with excess DDTC (100 μg mL−1) added to the test solutions, possible interferences from Cu2+ (up to 400 ng mL−1) could be eliminated. The proposed method was thus successfully applied to the determination of Cr(VI) in three real water samples and one certified reference water sample, as well as two simulated water samples of Cr(VI) and Cr(III), all with satisfactory results. The possible reasons were discussed for the varied degrees of enhancement between Cr(III) and Cr(VI).

Chemical Separation of Uranium and Precise Measurement of 234U/238U and 235U/238U Ratios in Soil Samples Using Multi Collector Inductively Coupled Plasma Mass Spectrometry

A new chemical separation has been developed to isolate uranium (U) using two UTEVA columns to minimize iron and thorium interferences from high background area soil samples containing minerals like monazites and ilmenite. The separation method was successfully verified in some certified reference materials (CRMs), for example, JSd-2, JLk-1, JB-1 and JB-3. The same method was applied for purification of U in Fukushima soil samples affected by the Fukushima dai-ichi nuclear power station (FDNPS) accident. Precise and accurate measurement of 234U/238U and 235U/238U isotope ratios in chemically separated U were carried out using a multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS). In this mass spectrometric method, an array of two Faraday cups (1011 Ω, 1012 Ω resistor) and a Daly detector were simultaneously employed. The precision of U isotope ratios in an in-house standard was evaluated by replicate measurement. Relative standard deviation (RSD) of 234U/238U and 235U/238U were found to be 0.094% (2σ) and 0.590% (2σ), respectively. This method has been validated using a standard reference material SRM 4350B, sediment sample. The replicate measurements of 234U/238U in SRM shows 0.7% (RSD). This developed method is suitable for separation of U and its isotope ratio measurement in environmental samples.

Do pride and shame track the evaluative psychology of audiences? Preregistered replications of Sznycer et al. (2016, 2017).

Are pride and shame adaptations for promoting the benefits of being valued and limiting the costs of being devalued, respectively? Recent findings indicate that the intensities of anticipatory pride and shame regarding various potential acts and traits track the degree to which fellow community members value or disvalue those acts and traits. Thus, it is possible that pride and shame are engineered to activate in proportion to others' valuations. Here, we report the results of two preregistered replications of the original pride and shame reports (Sznycer et al. 2016 Proc. Natl Acad. Sci. USA 113, 2625–2630. (doi:10.1073/pnas.1514699113); Sznycer et al. 2017 Proc. Natl Acad. Sci. USA 114, 1874–1879. (doi:10.1073/pnas.1614389114)). We required the data to meet three criteria, including frequentist and Bayesian replication measures. Both replications met the three criteria. This new evidence invites a shifting of prior assumptions about pride and shame: these emotions are engineered to gain the benefits of being valued and avoid the costs of being devalued.