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With the continuous petroleum extraction from deep-water subsea gas fields, many long distance offshore natural gas pipelines have been constructed. The design parameters directly affect the gas flow velocity in pipelines, which may introduce high wall shear stresses on the pipeline internal wall. Moreover, corrosive medium like CO2, H2S, O2, and Cl- always exists in subsea pipelines under high velocity gas flow, which induces erosion-corrosion. Many pipelines in China have entered the middle or late stage of service, and this has increased the risks and failures induced by erosion-corrosion. Furthermore, more natural gas storages are being built for transportation, which require a high-velocity gas flow for gas injection and production processes. A certain amount of corrosive mediums such as residual drilling fluid, hydrochloric acid, condensate water, CO2, and H2S can be found in natural gas, and when combined with a high gas flow velocity, internal erosion-corrosion might occur in the tubing in downhole systems. In this study, a high temperature-high pressure flow loop was applied to investigate the corrosion behavior of L80 steel in a wet gas pipeline with a high gas velocity. The extreme conditions created by the flow loop is 30 m·s-1 gas velocity, 0.0007% water cut, 0.5 MPa CO2 partial pressure, and 55℃ environmental temperature. Corrosion rates at different testing periods were calculated through weight-loss measurements. Confocal laser scanning microscopy and scanning electron microscopy were applied to observe the corrosion morphology. The corrosion product constituents were analyzed using X ray diffraction and energy dispersive spectroscopy (EDS), and the results reveal that severe corrosion occurs and a large number of micro pits appear on the L80 coupons surfaces. Moreover, instead of an integral corrosion prod-uct film, FeCO3 corrosion product chips and Fe3C are present on the steel.

Aiming at Smith controller' weakness of dealing with system disturbance, this paper presented a novel LM-Smith controller based on neural network identification. This algorithm used Levenberg-Marquardt neural network as Smith predictive model. Through online identification, predictive model could follow controlled object real-time, which solved Smith control' s inefficiency when control models mismatch. Simulation show that the controlling algorithm get the better of static characters, preferable dynamic quality and strong robustness. [ABSTRACT FROM AUTHOR]

The primary goal of national parks is to protect ecological environment, but also with the functions of scientific research, education, and recreation. Aiming for the realization of universal sharing, we used the analytic hierarchy process (AHP) to construct an ecotourism suitability evaluation system by selecting four factors, including landscape resources, ecological environment carrying capacity, recreation utilization capacity and social condition, taking Xiaoxiangling area of Giant Panda National Park and the surrounding communities as an example. We evaluated the ecotourism suitability based on GIS, and conducted a questionnaire survey of tourists, to propose suggestions on the functional zoning in terms of ecotourism suitability and subjective choice preferences of tourists. The results showed that the ecotourism suitability of the evaluation area could be classified into five levels. The most suitable areas were located nearby the natural landscape resources and far away from the core conservation area, and the least suitable areas distributed at the edge of the core conservation area. According to the results of suitability analysis, the evaluation area was divided into suitable development area, moderate development area, and restricted development area. Combined with the tourist preferences, we divided the recreational activities in the evaluation area into seven activities, namely, ecotourism, eco-camping, science education, leisure vacation, agricultural and animal husbandry culture experience, eco-education, and mountain adventure. These findings could help provide suitable services for different tourists and offer reference for the ecotourism developmental planning of the Xiaoxiangling area of the Giant Panda National Park.

The application of exogenous growth-regulating substances is an effective technique to enhance plant stress tolerance. Here, a hydroponic experiment was conducted to investigate the effects of exogenous basal application of 0.1 mmol·L -1 spermidine (Spd) on both the physiology and molecular biology of ryegrass root systems under varying degrees (0, 5, and 10 mg·L -1 ) of cadmium (Cd) stress using ryegrass as the test plants. The results of physiological studies revealed that Cd stress significantly reduced the physiological functions of the ryegrass root system, whereas the addition of Spd effectively alleviated the negative effects caused by Cd. The most significant effect was on the root soluble protein content, which increased by 90.91% and 158.35% compared with 5 mg·L -1 and 10 mg·L -1 Cd alone. Spd also inhibited the accumulation of oxidative stress products malondialdehyde (MDA) and hydrogen peroxide (H 2 O 2 ) by increasing the ascorbic acid (ASA) and glutathione (GSH) content and peroxidase (POD) activity, whereas the effects on root activity and superoxide dismutase (SOD) activity were not significant. The results of molecular biology studies demonstrated that 10 mg·L -1 Cd stress caused differential expression of a large number of genes in ryegrass roots, and the number of differentially expressed genes, differential significance, and differential multiplicity were significantly reduced after the application of exogenous Spd. The most significant part of the GO enrichment analysis shifted from responding to organic cyclic compounds and aldehyde/ketone group transferase activity to responding to trivalent iron ions and 2'-deoxymugineic-acid 2'-dioxygenase activity. Single gene expression heat map analysis revealed that exogenous Spd upregulated the expression of genes encoding zinc-iron transporter protein and 2'-deoxymugineic-acid 2'-dioxygenase, which improved the uptake and utilization of iron by the root system. In conclusion, the application of certain concentrations of Spd could effectively regulate the response of ryegrass roots to Cd stress, enhance its tolerance physiology, and mitigate the toxic effects of Cd.

To systemically evaluate the effect of Qishen Yiqi Dripping Pills combined with Western medicine on adverse cardiovascular events and quality of life after percutaneous coronary intervention(PCI). A total of 7 Chinese and English databases including CNKI, Wanfang, VIP, SinoMed, PubMed, Cochrane Library and Web of Science were searched by computer to collect the randomized controlled trials(RCTs) on Qishen Yiqi Dripping Pills combined with Western medicine in the treatment of patients with coronary heart disease after PCI with the retrieval time from the database establishment to April 1, 2020. Two researchers independently conducted li-terature screening, data extraction and bias risk assessment. Then, Meta-analysis was performed by using RevMan 5.3 software. A total of 31 RCTs were included, involving 3 537 patients. The results of Meta-analysis showed that in terms of major adverse cardiovascular events(MACE) after PCI, the combination of Qishen Yiqi Dripping Pills could significantly reduce the recurrence of angina pectoris, incidence of arrhythmia, heart failure and re-revascularization, and the effect was better than that of Western medicine treatment alone. However, there was no significant difference between the two groups in the improvement of non-fatal myocardial infarction, cardiac death, stent restenosis, stroke and other adverse cardiovascular events. In terms of improving left ventricular ejection fraction(LVEF), 6 min walking test(6 MWT), high-sensitivity C-reactive protein(hs-CRP) and Seattle angina pectoris scale(SAQ), the combination of Qishen Yiqi Dripping Pills and Western medicine treatment had obvious advantages over Western medicine treatment alone in increasing LVEF, 6 MWT and SAQ, and reducing the level of hs-CRP, with statistically significant differences. There were few adverse reactions in both groups, and there was no significant difference between the two groups. The main manifestations were gastrointestinal reactions, rash, gingiva and other small bleeding, and no serious adverse reactions occurred. The above reactions could disappear after drug withdrawal or symptomatic treatment. The application of Qishen Yiqi Dripping Pills combined with Western medicine in the treatment of patients after PCI could reduce the occurrence of MACE, improve the clinical efficacy, quality of life and prognosis in a safe and reliable manner. However, due to the quantity and quality limitations of included studies, more standardized, rigo-rous and high-quality clinical studies are still needed to further verify the above conclusions.

Objective: To explore the compliance rate of patients and its influential factors on topical antifungal treatment of onychomycosis., Methods: Dermatology life quality index (DLQI) and self-administered questionnaires were employed in this study., Results: The overall compliance rate of the topical antifungal treatment was 23.9% (92/385). The cure rates on onychomycosis in patients with good compliance was 63.04% (58/92), but only 2.05% (6/293) in those noncompliant patients, respectively. Regarding the influencing factors as age, sex, level of awareness, occupation, course of disease, personal income, inconvenience in access to the treatment, keep forgetting in taking the medicine, being impatient, lack of confidence, misunderstanding on topical as 'dirty' and the process of drug taking was troublesome, together with the quality of life were identified. There were significant differences between those compliant or noncompliant patients. For some factors as adverse effects of drug, number of affected nails, site of the disease, too busy in daily life, lack of related knowledge etc., no significant differences were found between the compliant or noncompliant patients., Conclusion: Our results showed that onychomycosis patients had poor compliance in topical antifungal treatment which significantly influencing the therapeutic effects. Age, sex, level of awareness on the disease, occupation, course of disease, personal income, inconvenience in receiving the treatment, forgetting to take the medicine, lack of patience, lack of confidence, different kinds of misunderstanding about the disease and quality of life etc. might affect the compliance rate of the disease.