Effects of Hydrogenation on the Corrosion Behavior of Zircaloy-4.

Hydrogen plays an important role in the corrosion of zirconium alloys, and the degree of influence highly depends on the alloy composition and conditions. In this work, the effects of hydrogenation on the corrosion behavior of Zircaloy-4 in water containing 3.5 ppm Li + 1000 ppm B at 360 °C/18.6 MPa were investigated. The results revealed that hydrogenation can shorten the corrosion transition time and increase the corrosion rates of Zircaloy-4. The higher corrosion rates can be ascribed to the larger stress in the oxide film of hydrogenated samples, which can accelerate the evolution of the microstructure of the oxide film. In addition, we also found that hydrogenation has little effect on the t-ZrO2 content in the oxide film and there is no direct correspondence between the t-ZrO2 content and the corrosion resistance of the Zircaloy-4.

Automated Segmentation and Classification of Knee Synovitis Based on MRI Using Deep Learning.

OBJECTIVES: To develop a deep learning (DL) model for segmentation of the suprapatellar capsule (SC) and infrapatellar fat pad (IPFP) based on sagittal proton density-weighted images and to distinguish between three common types of knee synovitis. MATERIALS AND METHODS: This retrospective study included 376 consecutive patients with pathologically confirmed knee synovitis (rheumatoid arthritis, gouty arthritis, and pigmented villonodular synovitis) from two institutions. A semantic segmentation model was trained on manually annotated sagittal proton density-weighted images. The segmentation results of the regions of interest and patients' sex and age were used to classify knee synovitis after feature processing. Classification by the DL method was compared to the classification performed by radiologists. RESULTS: Data of the 376 patients (mean age, 42 ± 15 years; 216 men) were separated into a training set (n = 233), an internal test set (n = 93), and an external test set (n = 50). The automated segmentation model showed good performance (mean accuracy: 0.99 and 0.99 in the internal and external test sets). On the internal test set, the DL model performed better than the senior radiologist (accuracy: 0.86 vs. 0.79; area under the curve [AUC]: 0.83 vs. 0.79). On the external test set, the DL diagnostic model based on automatic segmentation performed as well or better than senior and junior radiologists (accuracy: 0.79 vs. 0.79 vs. 0.73; AUC: 0.76 vs. 0.77 vs. 0.70). CONCLUSION: DL models for segmentation of SC and IPFD can accurately classify knee synovitis and aid radiologic diagnosis.

[Determination of furosine in liquid milk by high performance liquid chromatography-quadrupole time-of-flight mass spectrometry].

Furosine is often used both domestically and internationally as an indicator of the degree of heating to evaluate milk quality. However, in actual detection, the complexity of the milk matrix may lead to the inaccurate quantification of furosine in liquid milk. Therefore, in this study, an efficient and accurate method based on high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (HPLC-Q-TOF/MS) was established to determine furosine in liquid milk. A 2.00 mL milk sample was hydrolyzed with 5 mL 12.00 mol/L hydrochloric acid solution and 1 mL water at 110 ℃ for 12 h. After hydrolysis, vortex-mixing and filtration were performed. The filtrate was diluted six times with 6.00 g/L ammonium acetate solution and then analyzed. Gradient elution was performed with 0.20% formic acid aqueous solution and acetonitrile solution as mobile phases, followed by chromatographic separation on an AQ-C18 column (150 mm×3.5 mm, 5 µm). The data were collected by Q-TOF/MS with an electrospray ionization source operated in positive-ion mode. The accuracy of the quantification of furosine in milk was assessed by investigating the effects of the hydrochloric acid concentration (0.30, 1.25, and 3.00 mol/L) in the furosine solution on the MS response. The results showed that high hydrochloric acid concentrations inhibited the response signals. A good linear relationship was obtained in the mass concentration range of 0.05-2.00 mg/L, with a correlation coefficient (r) of 0.994. The limit of detection of the method was 0.50 mg/100 g, which meets the requirements of actual sample detection. The average recoveries of furosine ranged from 79.9% to 119.7% at three spiked levels of 1.52, 3.03, and 15.17 mg/100 g, with relative standard deviations of 1.4%-2.6%. The method was applied to detect 303 samples from 101 batches of pasteurized milk sold in the market, and the contents of furosine in these samples ranged from 5.1 to 11.9 mg/100 g. The proposed method is characterized with high efficiency, recovery, sensitivity, and accuracy. Thus, it can be used for the determination of large quantities of samples and provides technical support for the continuous promotion of the high-quality development of the whole dairy industry chain.

Unraveling different influences of the fraction of the tetragonal phase in oxide films on the corrosion resistance of Zr alloys from the phase transition mechanism.

The mechanism of Sn and Nb influence on the fraction of tetragonal ZrO2 in oxide films on Zr alloys and their influence mechanism on corrosion resistance of Zr alloys, despite decades of research, are ambiguous due to the lack of kinetic knowledge of phase evolution of ZrO2 with doping. Using stochastic surface walking and density functional theory calculations, we investigate the influence of Nb and Sn on the stability of tetragonal (t) and monoclinic (m) ZrO2, and t-m phase transition in oxide films. We found that though Nb and Sn result in similar apparent variation trends in the t-phase fraction in oxide films, their influences on t-m phase transition differ significantly, which is the underlying origin of different influences of the t-phase fraction in oxide films on the corrosion resistance of Zr alloys with Sn and Nb alloying. These results clarify an important aspect of the relationship between the microstructure and corrosion resistance of Zr alloys.

Evaluation of Deep Learning-Based Automated Detection of Primary Spine Tumors on MRI Using the Turing Test.

Background: Recently, the Turing test has been used to investigate whether machines have intelligence similar to humans. Our study aimed to assess the ability of an artificial intelligence (AI) system for spine tumor detection using the Turing test. Methods: Our retrospective study data included 12179 images from 321 patients for developing AI detection systems and 6635 images from 187 patients for the Turing test. We utilized a deep learning-based tumor detection system with Faster R-CNN architecture, which generates region proposals by Region Proposal Network in the first stage and corrects the position and the size of the bounding box of the lesion area in the second stage. Each choice question featured four bounding boxes enclosing an identical tumor. Three were detected by the proposed deep learning model, whereas the other was annotated by a doctor; the results were shown to six doctors as respondents. If the respondent did not correctly identify the image annotated by a human, his answer was considered a misclassification. If all misclassification rates were >30%, the respondents were considered unable to distinguish the AI-detected tumor from the human-annotated one, which indicated that the AI system passed the Turing test. Results: The average misclassification rates in the Turing test were 51.2% (95% CI: 45.7%-57.5%) in the axial view (maximum of 62%, minimum of 44%) and 44.5% (95% CI: 38.2%-51.8%) in the sagittal view (maximum of 59%, minimum of 36%). The misclassification rates of all six respondents were >30%; therefore, our AI system passed the Turing test. Conclusion: Our proposed intelligent spine tumor detection system has a similar detection ability to annotation doctors and may be an efficient tool to assist radiologists or orthopedists in primary spine tumor detection.

Determination of 22 alternative plasticizers in wrap film by solid phase extraction and ultra-high performance supercritical fluid chromatography-tandem mass spectrometry.

A rapid, accurate and novel analytical method based on ultra-high performance supercritical fluid chromatography-tandem mass spectrometry for determination of 22 alternative plasticizers in wrap film was developed. Instrumental analysis and sample preparation procedures were systematically optimized. The targets were separated on Torus 1-AA column (100 mm × 3 mm, 1.7 µm). Mobile phase A was supercritical carbon dioxide, and mobile phase B was ethanol/methanol (7:3, v/v) containing 0.1% formic acid and 0.5 mM ammonium acetate. Gradient elution was performed. The analytes were extracted by 10 mL n-hexane/dichloromethane (1:1, v/v), and further purified on silica solid phase extraction cartridges. The analytes were quantified by ultra-high performance supercritical fluid chromatography-tandem mass spectrometry with electrospray ionization source, and detection was performed on multiple reaction monitoring mode. Two commercially available isotopically-labelled internal standards were used for quantification calibration, and analytes were divided into two groups according to the more appropriate internal standards (chemistry similarity, closeness of retention time). Method validation was performed in terms of recovery, repeatability, linearity, sensitivity and matrix effect. Linearity was assessed using matrix-matched standard calibration. Satisfactory linearity (r2 ≥ 0.995), intra-day precision (RSDs ≤ 9.6%), inter-day precision (RSDs ≤ 10.9%), recovery (75.6-124.5%) as well as good selectivity was observed. The limits of detection were 0.04-10 µg/kg, while the limits of quantification were 1.0-50 µg/kg. Most targets did not show significant matrix effect. Validation results verified that the proposed method was efficient, rapid and sensitive. Eventually it was successfully applied to food wrap film analysis, and results indicated that DEHA, ATBC, DBA and TnBP were the most frequently detected plasticizers in wrap film samples,which was worthy of attention.

First-Principles Calculations to Investigate the Influence of Irradiation Defects on the Swelling Behavior of Fe-13Cr Alloys.

Ferritic/martensitic (F/M) steels whose matrix is Fe-Cr are important candidate materials for fuel cladding of fast reactors, and they have excellent irradiation-swelling resistance. However, the mechanism of irradiation-swelling of F/M steels is still unclear. We use a first-principles method to reveal the influence of irradiation defects, i.e., Frenkel pair including atomic vacancy and self-interstitial atom, on the change of lattice volume of Fe-13Cr lattice. It is found that vacancy causes lattice contraction, while a self-interstitial atom causes lattice expansion. The overall effect of a Frenkel pair on the change of lattice volume is lattice expansion, leading to swelling of the alloy. Furthermore, the diffusion properties of point defects in Fe-13Cr are investigated. Based on the diffusion barriers of the vacancies and interstitial atoms, we find that the defects in Fe-13Cr drain out to surfaces/grain boundaries more efficiently than those in pure α-Fe do. Therefore, the faster diffusion of defects in Fe-13Cr is one of important factors for good swelling resistance of Fe-13Cr compared to pure α-Fe.

[Simultaneous determination of eight additives in polyethylene food contact materials by ultrahigh-performance liquid chromatography].

Measurement of additive residues in food contact materials is important for safety monitoring at the initial stage. Most of the current studies focus on the determination of the migration amounts of chemical hazards from food contact materials into food simulants. Studies on chemical hazard residues in food contact materials are limited to monomers, oligomers, heavy metals, phthalic acid esters, and biphenols, which are known environmental pollutants. Only a few studies have investigated analysis methods for additive residues in food contact materials. In this study, the main factors (monitoring wavelength, chromatographic column, mobile phase, extraction solvent, etc.) that affect the accuracy and sensitivity of eight compounds, including three antioxidants, three light stabilizers, and two plasticizers, were investigated during sample preparation and instrument analysis. A method based on ultrahigh-performance liquid chromatography (UPLC) was developed for the simultaneous determination of these eight additives in polyethylene (PE). The PE food contact material sample was ground to homogenize the particle sizes under freeze-grinding. After comparing the extraction efficiencies of methylbenzene, chloroform, acetone, and acetonitrile, 2.0 g of the sample was extracted with methylbenzene at 80 ℃ and 10.34-11.72 MPa (1500-1700 psi) by accelerated solvent extraction (ASE) for 10 min once. The exaction solvent (10 mL) was transferred and concentrated to near dryness under a gentle stream of nitrogen gas and then re-dissolved in 10 mL of the initial mobile phase (70% (v/v) methanol in water). Finally, the eight compounds were analyzed by UPLC. After optimization of the analytical column and mobile phases, the eight analytes were separated on an ACQUITY UPLC BEH C8 chromatographic column (100 mm×2.1 mm, 1.7 µm) by gradient elution using water and acetonitrile as the mobile phases. The column oven temperature, flow rate of the mobile phase, and injection volume were 30 ℃, 0.3 mL/min, and 5 µL, respectively. The analytes were detected by a diode assay detector (DAD) in the scanning range of 210 nm to 400 nm. The monitoring wavelength was set at 230 nm, 250 nm, 280 nm, and 330 nm. External standard calibration curves were used for quantification. Under the optimized conditions, the calibration curves for the eight compounds showed good linearity in the range of 0.2 µg/mL to 10 µg/mL, and the correlation coefficients were >0.999. The recoveries in spiked blank polyethylene samples at the level of 0.05% were in the range of 83.8% to 103.4%, with relative standard deviations (RSDs) ranging from 0.14% to 7.86%. To validate the method, PE reference materials containing these eight compounds were manufactured at the content level of 0.2% to 0.9%. The recoveries using the prepared reference materials ranged from 63.5% to 118.5%, and the RSDs were in the range of 4.61% to 15.6%. The limits of detection (LODs, S/N=3) of all the eight compounds were 0.005% and the limits of quantification (LOQs, S/N=10) were 0.02%, in compliance with the current legislation. To assess the feasibility and potential of the proposed approach for routine analyses of these eight compounds, the developed method was applied to the analysis of these compounds in ten PE food packages and PE gloves. In six samples, tris(2,4-di-tert-butylphenyl)phosphite (Irganox 168) was detected at a level of 0.02%-0.07%, which was lower than the maximum level of this compound in PE food contact material products regulated in GB 9685-2016 at 0.2%. The method is compliant with the current legislation, and it can be used for the monitoring and supervision of these eight additives in PE food contact materials.

The Distribution of Li Ions in the Oxide Film Formed on Zircaloy-4 Corroded in Lithiated Water at 633 K.

Transmission electron microscopy (TEM), second ion mass spectrum (SIMS) and atom probe tomography (APT) techniques are used to study the Li ion distribution in the oxide formed on the rolling surface (SN) of Zircaloy-4 corroded in lithiated water with 0.01 M LiOH at 633 K/18.6 MPa. The results showed that the Li ions segregated in the grain boundaries and subgrain boundaries in the oxide film, but nearly no Li ions were found in the oxide around the interface between the oxide and matrix. Finally, we discussed the mechanism of the LiOH influence on the corrosion resistance of Zircaloy-4.

Simultaneous determination of 17 bisphenols in polycarbonate by ultra-high performance supercritical fluid chromatography with tandem mass spectrometry.

A novel method was developed for the first time for the determination of 17 bisphenols by ultra-high performance supercritical fluid chromatography with tandem mass spectrometry. Under the optimal conditions, 17 bisphenols were separated successfully on a high density diol column in 9 min using methanol and carbon dioxide as mobile phase. 0.02% ammonium hydroxide/methanol v/v was used as the post-column compensation solvent to improve response of mass spectrometry. Linear relations of matrix-matched calibration curve were favorable over the selected concentration range of 1-100 µg/kg with correlation coefficients greater than 0.9981. The method limit of detection and limit of quantitation were 0.1-0.5 µg/kg and 0.5-2.5 µg/kg, respectively. The average recoveries at three spiked levels in polycarbonate were in the range of 81.8-114.5%. Intra-day and inter-day precisions for six replicates were below 15.0%. This method was successfully applied to determine bisphenols in polycarbonate.

Effects of oxygen chemical potential on the anisotropy of the adsorption properties of Zr surfaces.

The anisotropy of metal oxidation is a fundamental issue, and the oxidation of Zr surfaces also attracts much attention due to the application of Zr alloys as cladding materials for nuclear fuels in nuclear power plants. In this study, we systematically investigate the diagram of O adsorption on low Miller index Zr surfaces by using first-principles calculations based on density functional theory calculations. We find that O adsorption on the basal surface, Zr(0001), is more favourable than that on the prism surfaces, Zr(112[combining macron]0) and Zr(101[combining macron]0), under strong O-reducing conditions, while O adsorption on the prism surface is more favourable than that of the basal surface under weak O-reducing conditions and the O-rich conditions. Our findings reveal that the anisotropy of adsorption properties of O on the Zr surfaces is dependent on the O chemical potential in the environment. Furthermore, the ability of the prism for O adsorption is stronger than that of the basal surface under the O-rich condition, which is consistent with the experimental observation that the oxidation of the prism Zr surface is easier than that of the basal surface. Systematic surveys show the adsorption ability of the surface under strong O-reducing conditions is determined by the low coordination numbers of surface atoms and surface geometrical structures, while the adsorption ability of the surface under weak O-reducing conditions and O-rich conditions is only determined by the low coordination number of surface atoms. These results can provide an atomic scale understanding of the initial oxidation of Zr surfaces, which inevitably affects the growth of protective passivation layers that play critical roles in the corrosion resistance of Zr cladding materials.

Simultaneous Analysis of Simple Coumarins and Furocoumarines in Cigarettes by Solid-Phase Extraction with Gas Chromatography-Mass Spectrometry.

A sensitive, high-throughput analytical method based on a GC-MS method was established for the simultaneous quantitative determination of two categories of harmful coumarins: simple coumarins (coumarin, 6-methylcoumarin, 7-methoxycoumarin, 3,4-dihydrocoumarin, and 7-ethoxy-4-methylcoumarin) and furocoumarines (psoralen, 8-methoxypsoralen, 5-methoxypsoralen, and trioxysalen). The nine analytes were extracted with ethyl acetate, purified with Oasis HLB solid-phase extraction (SPE) cartridges, and identified and quantitatively determined by GC-MS in selected-ion monitoring mode. The LODs and LOQs of these compounds were in the ranges of 12.5-21.2 and 41.6-70.0 µg/kg, respectively. Average recoveries for the nine analytes ranged from 72.7 to 86.6% at LOQ, 1.5× LOQ, and 2× LOQ spike levels, with RSDs that were typically lower than 5.1%. The SPE-GC-MS method developed in this study was initially applied to research coumarins in cigarette samples; it proved to be accurate, sensitive, convenient, and practical.

Simultaneous Determination of Coumarin and Its Derivatives in Tobacco Products by Liquid Chromatography-Tandem Mass Spectrometry.

In this paper an analytical method based on high performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) for the determination of coumarin and its derivatives in tobacco products was developed. The MS/MS fragmentation pathways of the eight coumarins were elucidated. The new analytical method was defined based on two main axes, an extraction procedure with acetonitrile and analyte detection performed by HPLC-MS/MS in electron impact mode. The excellent selectivity and sensitivity achieved in multiple reaction monitoring (MRM) mode allowed satisfactory confirmation and quantitation for the coumarin flavor additives. Under the optimized gradient elution conditions, it took only 4.5 min to separate all eight coumarins. Good linearity for all the analytes were confirmed by the correlation coefficient r², ranging from 0.9987 to 0.9996. The limits of detection (LODs) and limits of quantitation (LOQs) of these compounds were in the range of 0.5-1.7 µg/kg and 1.7-5.2 µg/kg, respectively. The average recoveries at three spiked levels (LOQ, 1.5LOQ, 2LOQ) were all in the range of 69.6%-95.1% with RSDs (n = 6) lower than 5.3%. The method of HPLC-MS/MS developed in this study was initially applied to the research of coumarin flavor additives in tobacco products collected from the located market in Beijing from China and proved to be accurate, sensitive, convenient and practical.