In-Orbit Instrument Performance Study and Calibration for POLAR Polarization Measurements

POLAR is a compact space-borne detector designed to perform reliable measurements of the polarization for transient sources like Gamma-Ray Bursts in the energy range 50-500keV. The instrument works based on the Compton Scattering principle with the plastic scintillators as the main detection material along with the multi-anode photomultiplier tube. POLAR has been launched successfully onboard the Chinese space laboratory TG-2 on 15th September, 2016. In order to reliably reconstruct the polarization information a highly detailed understanding of the instrument is required for both data analysis and Monte Carlo studies. For this purpose a full study of the in-orbit performance was performed in order to obtain the instrument calibration parameters such as noise, pedestal, gain nonlinearity of the electronics, threshold, crosstalk and gain, as well as the effect of temperature on the above parameters. Furthermore the relationship between gain and high voltage of the multi-anode photomultiplier tube has been studied and the errors on all measurement values are presented. Finally the typical systematic error on polarization measurements of Gamma-Ray Bursts due to the measurement error of the calibration parameters are estimated using Monte Carlo simulations.Comment: 43 pages, 30 figures, 1 table; Preprint accepted by NIM

Authenticating Tibetan pork in China by tracing the species and geographical features based on stable isotopic and multi-elemental fingerprints

peer reviewedA potential tool for authenticating Tibetan pork based on species and geographical origins was investigated by isotopic and multi-elemental fingerprints to compare Tibetan pork and plain pork from various regions in China. In this study, carbon, nitrogen, hydrogen and oxygen isotope compositions and concentrations of 50 elements of a total of 93 pork samples (Tibetan pork from Tibet and Sichuan, Jilin pork from Jilin and DLY pork from Liaoning) were determined and subjected to multivariate analysis, including linear discriminant analysis (LDA), partial least squares discriminant analysis (PLS-DA) and correlation analysis. The trace elements Fe, Cu, Rb, Mo, Cs, Ir, Co, Sr, Sm and four stable isotopes were determined as potential markers for identifying Tibetan pork. The discriminant model revealed good discrimination among pork samples based on species and regions, and the high accuracies of K-fold cross-validation (95.74% and 97.84%) indicated the reliability and stability of classification models. This study has demonstrated the efficiency of isotopic and multi-elemental technology in identifying Chinese high-altitude indigenous pigs

Discrimination of geographical origin and species of China's cattle bones based on multi-element analyses by inductively coupled plasma mass spectrometry.

peer reviewedConsumers have an increasing concern in the provenance of the foods they consume. Methods for discriminating geographical origins and species of cattle bone product are essential to provide veracious information for consumers and avoid the adulteration and inferior problems. In this study, 50 element contents of a total of 143 cattle bone samples from eight producing regions in China, were determined by inductively coupled plasma mass spectrometry (ICP-MS). Element contents were used as chemical indicators to discriminate species and geographical origins of cattle bone samples by multivariate data analysis, including hierarchical cluster analysis (HCA) and linear discriminant analysis (LDA). The K-fold cross validation accuracy for species and geographical origin discrimination was 99.3% and 94.5%, respectively. This study reveals that multi-element analysis accompanied by LDA is an effective technique to ensure the information reliability of cattle bone samples, and this strategy may be a potential tool for standardizing market

Morphological changes of mitochondria-related to apoptosis during postmortem aging of beef muscles

This study aimed to investigate how postmortem muscle cells' mitochondria changed in morphology from three aspects: the outer membrane, cristae, and fission/fusion. Atomic force microscopy (AFM) results showed that mitochondria underwent a morphology transformation from normal to swelling and collapse. Meanwhile, the cleavage of OPA1, upregulation of OMA1, downregulation of Mic60 and transmission electron microscope micrographs revealed that mitochondrial cristae ruptured with an aging time extended. Additionally, the increased expressions of Fis1 and Drp1, and the AFM topographic images mutually confirmed mitochondrial fission. These results further proved from the perspective of mitochondrial morphology that the degree of mitochondrial damage increased with the postmortem aging time extended, which was consistent with the results of the release of cytochrome c caused by the increase of mitochondrial permeability transition pore opening and the decrease of mitochondrial membrane permeability, and further induced the apoptosis of postmortem muscle cells

Preparation of cattle bone collagen peptides-calcium chelate and its structural characterization and stability

peer reviewedIn this study, cattle bone collagen peptides (CPs) were applied to prepare peptides-calcium chelate (CPs-Ca), and the physicochemical, structural properties, and stability of the CPs-Ca were characterized. The optimized preparation conditions were determined by single factor test, and the maximum calcium-chelating capacity was 42.70 ± 1.09 μg/mg. Physicochemical analysis indicated that CPs-Ca was a new substance compared with CPs. Structural analysis demonstrated that calcium ions chelated CPs via the sites of carboxyl oxygen, hydroxyl oxygen and amino nitrogen atom. Morphology analysis showed that CPs-Ca aggregated to large particles due to the crosslinking of calcium ions. According to the stability analysis, CPs-Ca was stable in thermal processing and gastrointestinal digestion. The acid environment was the major factor of CPs-Ca dissociation. The findings put forward a scientific basis for preparing a novel calcium supplement and high-value utilization of cattle bone

Evolution of sensory attributes and physicochemical indexes of Gouqi fermented wine under different aging treatments and their correlations

This study investigated the evolution of physicochemical indexes and taste parameters of Gouqi fermented wine during storage process, and further test if different aging treatments could affect the evolution pattern of these parameters. Results showed that bottle-aged wine exhibited an increase in the sourness, bitterness, and astringency compared to tank-aged wine during storage. Meanwhile, the umami, richness, and saltiness were weakened in wine aged in bottle. The sourness taste exhibited a positive correlation with the bitterness and astringency but was negatively correlated with the umami and richness in wine. Pearson coefficient analysis revealed that protein and total phenols were positively correlated with the umami. However, these physicochemical indexes showed a negative correlation with the wine sourness. The increase in the lactic acid concentration in bottle-aged wine during storage enhanced the wine bitterness. However, its content decrease lowered the umami taste in bottle-aged wine. Practical applications Wine aging process can result in Gouqi fermented wine with turbidity and further affect its sensory features. This present study indicated that different aging treatments altered taste and physicochemical parameters of Gouqi fermented wine during storage. The findings from this study could provide reference on the quality control of Gouqi fermented wine

The value of bronchodilator response in FEV1 and FeNO for differentiating between chronic respiratory diseases: an observational study

Abstract Background There is no uniform standard for a strongly positive bronchodilation test (BDT) result. In addition, the role of bronchodilator response in differentiating between asthma, chronic obstructive pulmonary disease (COPD), and asthma–COPD overlap (ACO) in patients with a positive BDT result is unclear. We explored a simplified standard of a strongly positive BDT result and whether bronchodilator response combined with fractional exhaled nitric oxide (FeNO) can differentiate between asthma, COPD, and ACO in patients with a positive BDT result. Methods Three standards of a strongly positive BDT result, which were, respectively, defined as post-bronchodilator forced expiratory volume in 1-s responses (ΔFEV1) increasing by at least 400 mL + 15% (standard I), 400 mL (standard II), or 15% (standard III), were analyzed in asthma, COPD, and ACO patients with a positive BDT result. Receiver operating characteristic curves were used to determine the optimal values of ΔFEV1 and FeNO. Finally, the accuracy of prediction was verified by a validation study. Results The rates of a strongly positive BDT result and the characteristics between standards I and II were consistent; however, those for standard III was different. ΔFEV1 ≥ 345 mL could predict ACO diagnosis in COPD patients with a positive BDT result (area under the curve [AUC]: 0.881; 95% confidence interval [CI] 0.83–0.94), with a sensitivity and specificity of 90.0% and 91.2%, respectively, in the validation study. When ΔFEV1 was < 315 mL combined with FeNO < 28.5 parts per billion, patients with a positive BDT result were more likely to have pure COPD (AUC: 0.774; 95% CI 0.72–0.83). Conclusion The simplified standard II can replace standard I. ΔFEV1 and FeNO are helpful in differentiating between asthma, COPD, and ACO in patients with a positive BDT result