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In order to meet the needs of accurate traceability of dose monitoring instruments in domestic medical, security inspection and other pulse radiation places, a 50-120 kV millisecond pulse X-ray reference radiation field that meets the requirements of norms and standards was established, based on the gate control technology, and its pulse width can be adjustable in the range of 1-6 300 ms. The pulse X-ray reference waveform was established by studying and testing the tube voltage stability, dose linearity, repeatability, pulse waveform and other key parameters of the radiation field, and the pulse dose rate was measured using a cylindrical ionization chamber with a sensitive volume of 30 cm3, and obtained the following research results: when the tube voltage was preset to 60 kV, the relative deviation of the intervened and non-intervened measuring tube voltage did not exceed ±1.5%; the minimum pulse width of the reference waveform pulse output was 20 ms, and a 95% uniform radiation field with a diameter of about 5.5 cm could be generated at 1 m. Moreover, the dose rate range of N series and RQR series radiation quality was extended to 0.002-10 mGy/s and 0.03-250 mGy/s, respectively, which can be used for the metrological traceability of protective instruments.

Human eye lens is an organ vulnerable to radiation damage. Through self-developed human skull model, a spherical ionization chamber was embedded in the ball to directly measure the eye lens individual dose equivalent Hp(3). Aiming at the accuracy evaluation of Hp(3) in radiation environment, the following research was carried out in this paper: Firstly, the instrument was calibrated under the S-Cs γ-ray radiation quality condition specified in the GB/T 12162.1 standard, and a calibration factor was obtained, NH=1.19 μSv/pC. Then, the correction factors k(E,α) were determined under different energy and incident angle conditions. At the same time, the background current and polarization effect were experimentally measured. Without the correction of energy and incident angle, the relative error of the energy response was -0.9%-12.6% in the energy range of 33 keV-1.25 MeV, and the relative error of the angle response was -7.9%-0% in the range of -60°-60°. At the same time, the factors affecting the accuracy of the measured value of the chamber were discussed. The relative expanded uncertainty of the calibration factor was 5.6% (k=2); when the energy and incident angle were known and unknown, the relative expanded uncertainty of the measured value of Hp(3) were 9.4% (k=2) and 18% (k=2) respectively. For radiation fields with unknown energy and incident angle, the Hp(3) value in the radiation field can be obtained directly by using the ionization chamber within the uncertainty range. This study can provide a reference for the accurate measurement of individual dose equivalent of eye lens.

In order to accurately measure the environmental level dose rate, based on the G(E) function method and conversion of complete spectra without deconvolution method, the energy spectrum and dose rate of X/γ ray was measured for calculating spectrum-dose conversion coefficient. And finally the conversion of energy spectrum to dose rate is realized. The residual difference between the calculated dose rate by the energy spectrum-dose method and the measured dose rate value is approximately 0, which proves that the method is self-consistent. Experiments have been conducted in 137Cs and 60Co radiation fields, and the maximum relative error of dose rate is ±10%, which proves that the G(E) function method and Conversion of complete spectra without deconvolution method are feasible for energy spectrum-dose conversion.

The confluence area serves as the pivotal control unit in natural rivers, and the implementation of spur dikes at the confluence enables regulation of flow patterns, influences pollutant mixing, and safeguards against river scouring. This study establishes a three-dimensional hydrodynamic model for the 90° confluence with dikes, aiming to explore the impact of the number, angle, and spacing of the dikes on hydrodynamic characteristics at 90° confluence. The results show that (i) the closer the spacing between the dikes, the wider the range of low water level area upstream becomes. An increased number of dikes makes it easier for the downstream water level to recover. (ii) The area of the high turbulent kinetic energy region increases with the increase in the number of dikes. Among the three angle deployments, the dike deployment angle of 60° corresponds to the largest area of high turbulent kinetic energy. When the spacing between dikes is 0.225 m, it results in the largest area of high turbulent kinetic energy. (iii) The number or spacing of dikes exhibits a negative correlation with the shape parameters of the separation and backflow behind the dikes, whereas there is a positive correlation between the angle of dikes and these shape parameters. (iv) Influenced by the deployment of dikes, novel helical flows will be generated around the dikes at the confluence. The helicity of the clockwise helical flow is comparatively smaller than that of its counterclockwise counterpart. Subsequently, newly generated helical flows undergo fusion and division as it progresses downstream. [ABSTRACT FROM AUTHOR]

Solid–liquid organic phase-change micro/nanocapsules are potential candidates for energy storage. Recently, significant progress has been made regarding phase-change micro/nanocapsules in terms of their synthesis, properties, and applications. Extensive research has been conducted to enhance their thermal properties, such as thermal storage capacity, thermal conductivity, and thermal reliability. However, factors that influence the thermal properties of micro/nanocapsules have received little attention. This study presents a comprehensive review of phase-change micro/nanocapsules focusing on their thermal properties and their influencing factors. In addition, the thermal properties of the major solid–liquid organic pure phase-change materials are summarized. Furthermore, common micro/nanoencapsulation methods and their influence on the thermal properties were analyzed. Finally, the potential applications of these phase-change micro/nanocapsules were also investigated. This study was devoted to enhancing the thermal properties of micro/nanocapsules, which play a crucial role in their practical applications. [ABSTRACT FROM AUTHOR]

Objective To investigate the changes of the upper airway shape and respiratory function in patients with mild and moderate obstructive sleep apnea⁃hypopnea syndrome (OSAHS) before and after wearing mandibular ad⁃ vancement snore stopping devices (MASSD), providing a reference and basis for the treatment mechanisms and clinical efficacy of MASSD for patients with mild and moderate OSAHS. Methods Sixty patients who were diagnosed with mild and moderate OSAHS by polysomnography were selected. Snoring frequency, the apnea hypopnea index and lowest oxygen saturation in 60 patients before and after treatment were compared. The patients’upper airways were scanned by CBCT before and after wearing MASSD. In Vivo Dental software was used to reconstruct the three⁃dimensional shape of upper airway. The upper airway sagittal diameter, the coronal diameter, the minimum cross⁃sectional area and the vol⁃ ume of each segment were measured. The snoring frequency, the apnea hypopnea index and the lowest oxygen satura⁃tion were compared before and after treatment. Results Before wearing MASSD, the snoring frequency, the apnea hy⁃ popnea index, and the minimum oxygen saturation of 60 patients were [946 (542,1 010)], (20.61 ± 5.19), and (78 ± 8)%, respectively. After wearing MASSD, the snore frequency [19(11,30)] and the respiratory disorder index (10.86 ± 4.31) decreased significantly and the minimum oxygen saturation increased (92 ± 3)% . Compared with before wearing MASSD, no statistically significance differences were detected (P > 0.05) except for the sagittal diameter and coronal di⁃ ameter of the surface of the palatum durum. The sagittal diameter and the coronal diameter of each plane of the airway increased, and the minimum cross⁃sectional area of each section of the airway and the volume of each section of the air⁃ way displayed varying degrees of significant increases (P < 0.001) after wearing MASSD. Conclusion Wearing MASSD can open the airways of patients with mild and moderate OSAHS and increase the airway volume of the upper airway to improve the respiratory function.

The Yellow River flows through multiple provinces in China, shaping the North China Plain, the largest alluvial plain in China. As the control node of basin ecological environment, the confluence of Weihe River and Yellow River is deemed as the gateway to North China Plain. In this study, a numerical simulation of the Weihe River–Yellow River confluence is conducted using a 2D hydrodynamic model and a coupled transport model for dissolved oxygen–biochemical oxygen demand. The results show that: (i) The typical flow field with multiple backflow areas is formed at the stagnant area where main stream and tributary converge and abrupt channel change area in different hydrological periods. The spur dike here mainly affects the velocity of the Weihe River outlet. (ii) There is an obvious concentration transition mixing zone downstream of the confluence, and the width of the mixing zone gradually linear increases with the direction of water flow. (iii) The self‐purification ability of the confluence is strongest in dry period, weaker in level period, and weakest in wet period. Water bodies have stronger self‐purification capacity on riverbanks than in the middle, and it is stronger in the upper reaches of Weihe River compared to Yellow River. Lower reaches also have a stronger self‐purification capacity than upper reaches. The study results can serve as a scientific reference for protecting the ecological environment of the Yellow River. [ABSTRACT FROM AUTHOR]

The quality of broadband power line carrier communication mainly depends on the carrier communication frequency. However, there is a lack of fast and effective optimal carrier frequency selection method. One frequency selection method based on frequency point optimization neural network is proposed by this paper. This method combines transmission line theory and voltage partial reflection theory to build a power line carrier channel mathematical model of the distribution network. The input frequency point sample set is used as the training set of the frequency point optimization neural network to obtain a neural network model that can predict the local optimal frequency point set. Then the actual distribution network is taken as an example for simulation analysis. When inputting any frequency range, the model outputs the corresponding optimal frequency point set. Simulation results show that the algorithm saves a lot of input impedance or channel strength testing time, while the error rate is limited to about 3%.

For the purpose of obtaining the smaller uncertainties for H p(3) and D p lens in 90Sr/90Y beta reference fields, a new dose determination method based on the Monte-Carlo simulation was proposed. The conversion coefficients from the absorbed dose in air, at the reference point of the extrapolation ionisation chamber, D air, det to H p(3; α) and the conversion factors from D air, det to D p lens(α) were calculated with EGSnrc, respectively, for the irradiation angles from 0° to 60°. Compared with the dose determination method in International Organization for Standardization (ISO) 6980 standard, the uncertainty reductions of 7.7–52.8% for H p(3; α) and 7.9–55.0% for D p lens(α) were achieved, respectively. In addition, for the conversion coefficients from the reference absorbed dose D R to H p(3; α), the calculations were performed for more irradiation conditions, which are not included in the current ISO 6980 standard. For the calculations of the conversion factors from D R to D p lens(α), the eye and head phantoms with Chinese characteristics were utilised, which makes the conversion factors more suitable for use in China. [ABSTRACT FROM AUTHOR]

This article proposes a novel dual-three-phase high-power high-speed permanent magnet assisted synchronous reluctance starter generator (PMaSynR SG) for aviation application, which has the characteristics of high efficiency, high power density, high reliability, and excellent antishort-circuit ability. The proposed PMaSynR SG can obtain higher efficiency and power density by embedding permanent magnet in the rotor topology compared with the synchronous reluctance generator, and has better antishort-circuit ability compared with the permanent magnet synchronous starter-generator. Moreover, design of dual-three-phase winding is adopted, which not only reduces the phase current, but also improves the reliability. In this article, the topological structure, characteristics and principle of PMaSynR SG are systematically studied at first. Second, a simplified dq-axis equivalent magnetic circuit model is established, and the expressions of dq-axis inductance and permanent magnet flux linkage are derived on the basis of the basic parameter selection. Then, combined with parameter sensitivity analysis, the influence law of rotor structural parameters on antishort-circuit ability and electromagnetic performance is revealed. Finally, a 40 kW 24 000 r/min PMaSynR SG is designed and manufactured. The simulation and experimental results show that the proposed PMaSynR SG has excellent electromagnetic performance with the power density of 3.1 kW/kg and the efficiency of 94%, while the short-circuit current is only 59% of its rated value. [ABSTRACT FROM AUTHOR]

Background and Aim: Serum pepsinogens (PGs) are biomarkers for gastric mucosal damage and have been reported to be associated with atherosclerosis. Its correlation with atherosclerotic cardiovascular disease (ASCVD) is still unknown. This study aimed to explore the association between serum PGs and ASCVD for providing physicians with an integrative picture to make rational plans in the diagnosis and treatment of ASCVD.Methods and Results: The concentrations of serum PGs and their distributions between ASCVD and non-ASCVD were compared by non-parametric test, Chi-squared test and Fisher exact test. The correlation between variables was analyzed by Spearman's correlation test. The association of serum PGs with ASCVD was analyzed by the binary logistic regression and two-piecewise linear regression. A total of 8355 recruited cases were eligible for the study. The concentrations of serum PGs were significantly different between the ASCVD and non-ASCVD groups (P = 0.025, P < 0.001). The lower PGI and PGR levels were significantly correlated with a high risk of ASCVD presence after adjustment for 26 potential covariates. Moreover, there was a linear relationship between the high level of PGII and the high risk of ASCVD [adjusted OR = 1.16 (1.00, 1.37), P = 0.07]. A nonlinear relationship of PGI/PGR and ASCVD (P = 0.08/<0.001) was also revealed. The risk of ASCVD increased with a range of log PGI ≥2.13 (PGI≥131 ng/mL) [adjusted OR = 4.67 (1.00, 23.17)], and decreased with a range of log PGR ≥0.22 (1.65) [adjusted OR = 0.59 (0.48, 0.74), P < 0.001].Conclusions: Serum PGI and PGR are nonlinearly correlated with ASCVD, while PGII is linearly correlated with ASCVD. Among all PGs, PGR may serve as a reliable biomarker for ASCVD. [ABSTRACT FROM AUTHOR]

Bangladesh is one of the most densely populated countries in the world. There are 57 trans‐frontier rivers in the country, the widest being the Brahmaputra River. The river's channels have frequently changed course, but the relationship between such river migrations and human settlement patterns has remained unstudied. In this paper, optically stimulated luminescence and radiocarbon dating techniques were applied to sedimentary and organic materials in the oldest urban center (Wari‐Bateshwar) in Bangladesh. The results showed that the landscape around the urban center was dominated by floodplain and peatland facies between 7.9–7.6 and 4.7–1.6 ka, respectively. Humans occupied this area at ~3.2 ka, and manufactured delicate semi‐precious gemstone beads between ~2.4 and 1.8 ka. The urban center might be the same as an important city of the Gangaridai described in historical records. Due to fluvial migration at ~1.8 ka, the area surrounding the urban center was covered by fluvial sand. Humans might have been forced to abandon the urban center, leading to the bead processing technology in Bangladesh being lost forever. [ABSTRACT FROM AUTHOR]

The development of life beyond planet Earth is a long-standing quest of the human race, but whether normal mammalian embryonic development can occur in space is still unclear. Here, we show unequivocally that preimplantation mouse embryos can develop in space, but the rate of blastocyst formation and blastocyst quality are compromised. Additionally, the cells in the embryo contain severe DNA damage, while the genome of the blastocysts developed in space is globally hypomethylated with a unique set of differentially methylated regions. The developmental defects, DNA damage and epigenetic abnormalities can be largely mimicked by the treatment with ground-based low-dose radiation. However, the exposure to simulated microgravity alone does not cause major disruptions of embryonic development, indicating that radiation is the main cause for the developmental defects. This work advances the understanding of embryonic development in space and reveals long-term extreme low-dose radiation as a hazardous factor for mammalian reproduction. [ABSTRACT FROM AUTHOR]