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The ventilation work is an important step to be completed before the start of the positive pressure explosion-proof robot. The existing explosion-proof technology uses constant pressure inflation, which will cause explosive gas to accumulate in the corner area of the cavity for a long time. In order to solve this problem, a ventilation method with periodic pulse intake is proposed. Based on the finite element method, the cleaning and ventilation process of the positive pressure explosion-proof robot is simulated and analyzed. The concentration of explosive gas in the robot cavity with time under constant pressure intake and pulse intake with different periods and amplitudes is compared. The simulation results show that the pulse intake is beneficial to the ventilation of the corner position. The period and amplitude of the pulse intake has an effect on the ventilation efficiency, when the period is the same, the greater the amplitude of the pulse intake, the higher the ventilation efficiency; when the amplitude is the same, the smaller the period of the pulse intake, the higher the ventilation efficiency. After experimental verification, the validity of the simulation results is proved. This study helps to improve the ventilation efficiency of positive-pressure explosion-proof robots and provides guidance for practical applications. [ABSTRACT FROM AUTHOR]

The founding processes of the first state of ancient China with a known written record, the Shang dynasty (3600–3046 cal BP), have been poorly understood. Recent discoveries of a host of archaeological sites dating to the proto-Shang culture (4000–3600 cal BP) have helped elucidate the transition to the Shang culture. Nevertheless, there are few investigations about the mode of subsistence and economy of the proto-Shang culture, and how this might have shaped the transition to statehood. In this present study, we analyzed the starch grains preserved in dental calculus and teeth surfaces from 16 samples from the site of Nancheng in order to gain a better understanding of the subsistence strategy and plant consumption of proto-Shang people. We also performed experiments to test how different cooking methods may lead to size changes in the starches of four Poaceae plants, in order to identify the processing methods used by the proto-Shang people. The results indicate that Triticum aestivum, Coix lacryma-jobi, Setaria italica and some yet-unidentified roots and tubers were consumed by these individuals. These data indicate a broader spectrum of plant consumption than that seen by previous archaeobotanical and stable isotope analyses. Such a broad spectrum of plant consumption provided a substantial economic base for proto-Shang people and might be one of the factors supporting the subsequent development of the Shang state culture. [ABSTRACT FROM AUTHOR]

Electrocardiographic and electrophysiological characteristics of VAs originating from the vicinity of the TA are not fully understood. Hence, 104 patients (mean age 52.6 ± 17.9 years; 62 male) with VAs originating from the vicinity of the TA were enrolled. After electrophysiological evaluation and ablation, data were compared among those patients. The ECGs and the correction of the ECGs based on the long axis of the heart calculated from the chest X-Ray were also analyzed. VAs originating from the vicinity of TA had distinctive ECG characteristics that were useful for identifying the precise origin. Our localization algorithm adjusted by the angle between the cardiac long axis and the horizon was found to be accurate in predicting the exact ablation site in 92.3% (n = 96) cases. Logistic regression analysis showed fractionated electrograms, the magnitudes of the local atrial electrograms and a/V ratio were critical factors for successful ablation. Among the 104 patients with VAs, complete elimination could be achieved by RFCA in 96 patients (success rate 92.3%) during a follow-up period of 35.2 ± 19.6 months. This study suggests that the ablation site could be localized by ECG analysis adjusted by the angle between the cardiac long axis and the horizon. Fractionated electrograms, the magnitudes of the local atrial electrograms and a/V ratio were demonstrated to be critical factors for successful ablation. [ABSTRACT FROM AUTHOR]

In current palaeodietary research, gelatinization is the main method to extract insoluble collagen (ISC) from ancient bones. However, the degradation products of ISC, i.e., soluble collagen (SC), is often neglected and abandoned. In this work, we try to separate the extracts of ancient bones using gel chromatography and compare the contents of carbon and nitrogen, atomic C/N ratio, and stable carbon and nitrogen isotopic values of the extracts from three peaks to determine which peak can be attributed to SC. At last, the potential application of SC in palaeodietary research is discussed based on the comparison of stable isotopic values between ISC and SC. Among the three peaks, the second with the retention time between 17.5 min and 27.5 min had the most broad peak shape, indicating that the molecular weights of proteins collected were most variable. Besides, the contents of carbon and nitrogen and atomic C/N ratio of extracts in this peak were closest to the corresponding ISC. Based on the above, we conclude that the extract in second peak is SC. More important, the δC and δN values of ISC and SC are very similar. For ISC and SC with atomic C/N ratios within the normal range (2.9-3.6), the mean difference of δC value was only (0.3±0.2)‰ ( n=2) while δN value was (0.6±0.1)‰ ( n=2). Although the atomic C/N ratios of some SC are slightly beyond the normal range, the mean differences of δC and δN values were still only (0.4±0.1)‰ and (0.3±0)‰ ( n=2) respectively. These isotopic differences are quite below the isotope fractionation in one trophic level ( δC values of 1‰-1.5‰ and δN values of 3‰-5‰), suggesting that SC had great application potentials in palaeodietary research. [ABSTRACT FROM AUTHOR]

Historical records and archaeological remains indicate that the Chinese agricultural economy changed significantly from the Warring States (475-221 BC) to Han Dynasties (206 BC-220 AD), i.e., from rice-millet based agriculture to rice-millet-wheat based agriculture. However, the variation of human diets and the inner relationship between human diets and the agricultural transition during this period remain poorly understood. In this paper, the C and N stable isotopes from human and animal bones at the Shenmingpu site (SMPS), Xichuan County, Henan Province were analyzed. If some outliers (M34, M36, M102) were excluded, the mean δC value ((−16.7±0.8)‰, n=15) of humans in Han Dynasties was dramatically lower than that in the Warring States ((−12.7±0.8)‰, n=14), indicating that the cultivation of rice and wheat, especially wheat, had been more widely popularized in Han Dynasties. Meanwhile, the range of δN values of humans (6.6‰-9.3‰) in Han Dynasties was narrower than that of the Warring States (6.2‰-10.4‰), suggesting that the animal protein resources in human foods during Han Dynasties were more concentrated. The transition of human diets and the close relationship with the change of agricultural economy in SMPS were due to more stable society, the carryout of new agricultural policies, and the emergence of new agricultural tools in Han Dynasties [ABSTRACT FROM AUTHOR]