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The electromagnetic wave energy emitted by wireless communication equipment in coal mines can be coupled and absorbed by surrounding metal structures, which poses a risk of igniting explosive gases in the mine. The existing research on the safety of underground metal structure coupled electromagnetic waves only focuses on the analysis of the energy of metal structure equivalent impedance model coupled electromagnetic waves. It lacks research on the energy storage process of metal structure coupled electromagnetic wave energy accumulated over time. In order to solve the above problems, an equivalent energy storage structure model suitable for studying the coupling-accumulation-release electromagnetic wave energy of metal structures is proposed, namely the metal structure equivalent capacitive energy storage model and the metal structure equivalent inductive energy storage model. Firstly, by using a low attenuation transmission line model, the relationship between the output power of the transmitting antenna, the distance between the transmitting antenna and the metal structure, and the induced voltage at the receiving end is derived. Secondly, an equivalent energy storage model of metal structure is established. The mathematical relationship between the receiving end parameters and the discharge spark energy is derived. The influence of the receiving end parameters on the discharge spark energy is analyzed. Finally, the mathematical relationship between the output power of the transmitting antenna, the distance between the transmitting antenna and the metal structure, and the discharge spark energy is derived by analyzing the relationship between the induced voltage at the receiving end and the effective value of the induced voltage. The influence of the output power of the transmitting antenna and the distance between the transmitting antenna and the metal structure on the discharge spark energy is analyzed. The theoretical reference safety points of the equivalent energy storage models of the two metal structures are given under the condition of other parameters being determined. The simulation results show the following points. ① For the equivalent capacitive energy storage model of metal structures, the discharge spark energy increases with the increase of the effective values of the equivalent energy storage capacitor and the induced voltage at the receiving end, and the safety point shifts to the left. The safety requirements for the effective values of the equivalent energy storage capacitor and the induced voltage at the receiving end become stricter. ② The energy of the discharge spark increases with the increase of the transmitting antenna power, and decreases with the increase of the distance between the transmitting antenna and the metal structure. The theoretical reference safety point of the equivalent capacitive energy storage model of the metal structure is obtained. ③ For the equivalent inductive energy storage model of metal structures, the discharge spark energy increases with the increase of the effective values of the equivalent energy storage inductance and the induced voltage at the receiving end, and the safety point shifts to the left. The safety requirements for the effective values of the equivalent energy storage inductance and the induced voltage at the receiving end become stricter. ④ The energy of the discharge spark increases with the increase of the transmitting antenna power, and decreases with the increase of the distance between the transmitting antenna and the metal structure. The theoretical reference safety point of the equivalent inductive energy storage model of the metal structure is obtained. ⑤ Comparing the theoretical reference safety points of two metal structure energy storage models, it is concluded that the danger of the metal structure equivalent capacitive energy storage model is much greater than that of the metal structure equivalent inductive energy storage model.

To study the problem that there is a horizontal sidesway between transfer and receiver coils in magnetic resonance coupling wireless power transfer, the mutual inductance coupling theory and twoport network theory is adopting for modeling analysis.The expression of normalized transmission power and transmission efficiency expressed by s parameter by mathematical derivation.The HFSS software is utilized to simulate the impact of the horizontal sidesway on system's transmission performance under the condition of overcoupling, critical coupling and undercoupling.An optimal structure for improving the system is presented.In the end, the reliability of simulation results is verified by experiment, and the experiment proves that the optimized structure should eliminate the negative effect brought by the sidesway effectively, and improve the transmission efficiency of the system.

Principle of magnetic resonance coupling wireless power transmission system was analyzed by use of mutual inductance theory. Impedance matching theory and corresponding parameter calculation methods were introduced. A model of magnetic resonance coupling wireless power transmission system containing an impedance matcher was built by equaling variation of mutual inductance between sending coil and receiving coil to variation of the system impedance parameters. The simulation result proves that magnetic resonance coupling wireless power transmission system containing an impedance matcher can improve load power effectively under the same condition.

Requirements of coal mine underground were analyzed for wireless power energy transmission. Characteristics of three kinds of wireless power transmission technologies were researched including microwave type, electromagnetic induction and magnetic coupling resonant type as well as their applicability in coal mine underground. It was considered that magnetic coupling resonant type wireless power transmission technology could be applied in coal mine underground. Impacts of different obstacles were analyzed emphatically on transmission efficiency of magnetic coupling resonant wireless power transmission system. A simulation model of magnetic coupling resonant wireless power transmission system was built by using HFSS 3D electromagnetics simulation software, and simulated experiments were carried out using metallic obstacles and the nonmetallic ones. The experimental results show that nonmetallic obstacles have no influence on transmission efficiency of the system, and metallic obstacles reduce transmission efficiency, especially in condition of adding thickness or reducing lateral area of the metallic obstacles.

To explore the feasibility of developing fishery aquaculture in low salt water, this study compared and analyzed the desalination effect of Sinonovacula contricta under different domestication methods. In this experiment, three groups with different low-salt domestication methods were set up (group Da: isokinetic domestication group with salinity decreased by 3 per 48 h; Group Db: isokinetic domestication group with salinity decreased by 1.5 per 24 h; group Dc: segmented domestication group with salinity decreased by 3 per 48 h before 10 and salinity decreased by 1 per 24 h after 10) and undomesticated group (Ud : salinity 5), water salinity decreased from 20 to 5, and the desalination period was 10 d. The survival, oxygen consumption rate, ammonia nitrogen excretion rate, feeding rate and antioxidant enzyme activity of clams in each experimental group were measured. The results showed that the survival rate of S. contricta in all domesticated groups was significantly higher than that of undomesticated group (43%), and the survival rate of group Dc (86%) was the highest. The oxygen consumption rate and ammonia nitrogen excretion rate in group Dc were significantly lower than those in group Da and group Db. The feeding experiments showed the feeding rate of group Dc was significantly higher than group A and group B. S. constricta in group Dc showed the least fluctuation of activities of superoxide dismutase (SOD) and catalase (CAT). In brief, the segmented desalination mode with a lower desalination rate and gradually decreasing the desalination rate with the decrease of salinity had significant advantages, which provided a reference for the desalination culture of S. contricta in low-saline water. [ABSTRACT FROM AUTHOR]

Objective: To assess the clinical efficacy and health economic value of non-invasive prenatal testing (NIPT) for the prenatal screening of common fetal chromosomal aneuploidies., Methods: 10 612 pregnant women from October 2017 to December 2019 presented at the antenatal screening clinic of the General Hospital of Tianjin Medical University were selected as the study subjects. Results of NIPT and invasive prenatal diagnosis and follow-up outcome for the 10 612 pregnant women were retrospectively analyzed and compared. Meanwhile, NIPT data for two periods were analyzed for assessing the health economic value of NIPT as the second- or first-tier screening strategy for the prenatal diagnosis of fetal trisomies 21, 18 and 13., Results: The NIPT was successful in 10 528 (99.72%) subjects, with the sensitivity for fetal trisomies 21, 18 and 13 being 100%, 92.86% and 100%, and the positive predictive value (PPV) being 89.74%, 61.90% and 44.44%, respectively. The PPV of NIPT for sex chromosome aneuploidies was 34.21%. Except for one false negative case of trisomy 18, the negative predictive value for trisomy 21, trisomy 13 and other chromosomal abnormalities were 100%. For pregnant women with high risk by serological screening, advanced maternal age or abnormal ultrasound soft markers, NIPT has yielded a significantly increased high risk ratio. There was no statistical difference in the PPV of NIPT among pregnant women from each subgroup. NIPT would have higher health economic value as a second-tier screening until 2019, while compared to 2015 ~ 2017, its incremental cost-effectiveness ratio as a first-tier screening had declined clearly., Conclusion: The screening efficacy of NIPT for trisomies 21, 18 and 13 for a mixed population is significantly better than conventional serological screening, but it is relatively low for sex chromosomal abnormalities. NIPT can also be recommended for populations with relatively high risks along with detailed pre- and post-test genetic counselling. From the perspective of health economics, except for open neural tube defects, it is possible for NIPT to replace the conventional serological screening in the future as its cost continues to decrease.

Objective: To comprehensively understand the basic construction of intensive care unit (ICU) in the secondary and tertiary hospitals in Xinjiang Uygur Autonomous Region, and to provide a theoretical basis for the development direction of critical care medicine and the rational allocation of medical resources in our region., Methods: On the March 14th, 2020, a cross-sectional survey of 147 ICU in 122 hospitals in Xinjiang Uygur Autonomous Region was conducted using an online questionnaire. The survey included 6 modules: the basic conditions of the hospital, ICU profile, ICU human resources status, equipment allocation, technology development, and ICU quality control., Results: Among the 147 ICUs, there were 69 ICUs in tertiary hospital and 78 ICUs in secondary hospital. 75.51% (111/147) were comprehensive ICU and 24.49% (36/147) were specialized ICU. The total number of ICU beds was 1 818, accounted about 2.43% (1 818/74 912) of the total number of hospital beds. In ICU terms of human resourse, physicians/beds ratio was 0.54:1, and nurses/beds ratio was 1.55:1. Physicians/beds ratio in the secondary hospitals was 0.52:1, and nurses/beds was 1.45:1; physicians/beds ratio in the tertiary hospital was 0.56:1, and nurses/beds ratio was 1.79:1. The ICU management model was mainly closed management (82.99%, 122/147), and the proportion of closed management in tertiary hospitals was 88.41% (61/69), which was higher than that in secondary hospitals (78.21%, 61/78). In aspect of ICU equipment, the invasive ventilator/bed ratio, enteral nutrition infusion pump/bed ratio, and blood purifier/bed ratio in the tertiary hospitals were significantly higher than those in the secondary hospitals [0.70 (0.46, 1.00) vs. 0.45 (0.33, 0.67), 0.18 (0.00, 0.56) vs. 0.00 (0.00, 0.13), 0.08 (0.00, 0.13) vs. 0.00 (0.00, 0.10), respectively, all P < 0.01]. In the tertiary hospital, the chest sputum excretion device, blood gas analyzer, blood purification instrument, transport ventilator, fiber bronchoscope, enteral nutrition infusion pump, bedside ultrasound machine, continuous hemodynamics and oxygen metabolism monitor, electroencephalogram bispectral index monitor, bedside electroencephalography machine and extracorporeal membrane oxygenation (ECMO) were also superior to the secondary hospitals. ICU technologies, such as deep venipuncture, jejunal nutrition tube placement, percutaneous tracheotomy, invasive blood pressure monitoring, invasive hemodynamic monitoring, bedside ultrasound examination, continuous blood purification, fiber bronchoscopy, high frequency ventilation, intra-aortic balloon counterpulsation (IABP), and ECMO had also performed better than secondary hospitals. In the management of ICU medical quality control, in tertiary hospitals, the proportions of single or isolated room for patients with drug-resistant bacteria, 1-hour bundle and hemodynamic monitoring for patients with septic shock, routine prone position ventilation and lung recruitment for patients with acute respiratory distress syndrome (ARDS), common analgesic, and use of personal digital assistant (PDA) for pre-operation scan code by nurses and electronic medical record for routine rounds were significantly higher than those in secondary hospitals (91.30% vs. 85.90%, 68.12% vs. 48.72%, 85.51% vs. 70.51%, 28.99% vs. 12.82%, 85.51% vs. 61.54%, 76.81% vs. 61.54%, 71.01% vs. 29.49, 49.28% vs. 28.21%, respectively), and the differences were statistically significant (all P < 0.05). 89.74% (70/78) ICU in secondary hospitals and 89.86% (62/69) of tertiary hospitals used acute physiology and chronic health evaluation II (APACHE II) to evaluate the severity of critically ill patients; in terms of sequential organ failure assessment (SOFA), the difference between the secondary hospitals and the tertiary hospitals was not statistically significant (51.28% vs. 62.32%, χ 2 = 1.814, P = 0.178)., Conclusions: Although the ICU construction of the tertiary hospitals in Xinjiang Uygur Autonomous Region is more complete than secondary hospitals, there is a big gap between the requirements of the national guidelines and the developed regions in the east. The ICU's investment in human resource, equipment and supporting facilities allocation, promotion of suitable technology, and medical quality control management should be increased to promote the development of critical care medicine in Xinjiang Uygur Autonomous Region.

Objective: To investigate the effect of terlipressin on prognosis of adult septic shock patients., Methods: All randomized controlled clinical trials (RCT) of terlipressin in the treatment of adult septic shock patients from January 1980 to December 2019 were retrieved from CNKI, Wanfang, SinoMed, PubMed, Embase, Springer Link, Cochrane Library, Google Scholar, and etc. Patients in the treatment group received terlipressin while patients in the control group received norepinephrine or other vasopressors. Main outcome indicator was mortality. Secondary outcome indicators included the incidence of severe adverse events, limb peripheral ischemic events and renal complications. Literature screening, data extraction and quality evaluation were conducted by two researchers respectively. Meta-analysis was performed with RevMan 5.3 software. Funnel plot was used to analyze the publication bias., Results: A total of 507 related literatures were retrieved. According to the inclusion and exclusion criteria, 8 RCT studies were finally included, with a total of 811 patients. One study was considered to have a lower risk of bias, 6 studies had uncertain risk of bias, and 1 study had a higher risk of bias. The Meta-analysis showed that terlipressin did not significantly improve the mortality of septic shock patients compared with the control group [odds ratio (OR) = 0.89, 95% confidence interval (95%CI) was 0.67-1.19, P = 0.45]; increased the incidence of severe adverse events (OR = 2.98, 95%CI was 1.99-4.45, P < 0.000 01); there was a tendency to increase the incidence of limb peripheral ischemic events, but without statistical difference (OR = 10.81, 95%CI was 0.88-133.19, P = 0.06); and reduced the incidence of renal complications (OR = 0.30, 95%CI was 0.09-0.96, P = 0.04). Funnel plot analysis indicated that there might be publication bias in a study on case fatality and incidence of serious adverse events in the included literature. No significant publication bias was found in studies on the incidence of limb peripheral ischemic events and the incidence of kidney-related complications., Conclusions: The available evidence suggests that terlipressin could not significantly improve mortality in adult's septic shock patients, but it may reduce the incidence of renal complications. A tendency to increase the incidence of limb peripheral ischemic events in the terlipressin-treated group needs to be emphasized.

Objective: Sepsis is one of the leading causes of inpatient deaths worldwide and is a major challenge in clinical work. The diagnosis and treatment of sepsis has been a research hotspot in critical care medicine. Through the efforts during the past decades, deeper understanding of the pathophysiology of sepsis and progress in the treatment have been made. But the latest sepsis guidelines and bundle strategies remain controversial, and clinical researches on sepsis are mixed. So far, there is no specific therapy for sepsis, and the mortality is still very high. Important researches and viewpoints in the field of sepsis in recent years are summarized and analyzed, so as to provide reference for the treatment of sepsis patients.

Objective: To systematically evaluate the effect of vitamin C on prognosis of critically ill patients., Methods: Randomized controlled trials (RCT) about vitamin C treatment for critically ill patients were searched in CNKI, CBM, VIP database, Wanfang database, PubMed, Springer Link, Embase, Web of Science, and Cochrane Library from their inception to May 2019. Patients in the treatment group received ascorbic acid while patients in the control group received placebo or other treatment. Outcome measures included mortality, the length of intensive care unit (ICU) stay, the length of hospital stay, and incidence of atrial fibrillation. Two researchers were responsible for literature screening, data extraction and quality evaluation independently. Meta-analysis was performed with RevMan 5.2 software. The publication bias was analyzed by funnel plot., Results: A total of 28 RCTs were enrolled and 4 420 patients were included (2 207 in intervention group and 2 213 in control group). Meta-analysis showed that there was no significant difference in mortality between intervention group and control group [odds ratio (OR) = 0.90, 95% confidence interval (95%CI) = 0.75 to 1.08, P = 0.27]. The length of ICU stay [mean difference (MD) = -0.23, 95%CI = -0.29 to -0.16, P < 0.000 01] and the length of hospital stay (MD = -0.96, 95%CI = -1.21 to -0.70, P < 0.000 01) in intervention group were less than those in control group. Subgroup analysis showed that mortality of patients with sepsis and septic shock in intervention group was lower than that in control group (OR = 0.65, 95%CI = 0.43 to 0.99, P = 0.04). For patients undergoing cardiac surgery, the incidence of postoperative atrial fibrillation in intervention group was lower than that in control group (OR = 0.43, 95%CI = 0.34 to 0.54, P < 0.000 01). It was shown by funnel plot that there was less publication bias among studies., Conclusions: Vitamin C does not reduce mortality in critically ill patients, but it can reduce the length of ICU stay and hospital stay. In addition, vitamin C can reduce mortality of patients with sepsis and septic shock and reduce the incidence of atrial fibrillation post operation in patients undergoing cardiac surgery.

Objective: To systematically evaluate the effect of high-flow nasal cannula oxygen (HFNC) on improving the atelectasis and respiratory function in adults after cardiac surgeries., Methods: All randomized controlled trials (RCTs) about HFNC therapy for adults after cardiac surgeries published from January 2000 to March 2018 were searched through CNKI, CBM, VIP, Wanfang, PubMed, Springer Link, Embase, Web of Science, Cochrane Library. The references from relevant articles were searched. The experimental group was treated with HFNC while the control group treated with conventional oxygen therapy (COT). The outcome measurements included radiological atelectasis score (RAS), endotracheal reintubation rate and the length of intensive care unit (ICU) stay. Two researchers were responsible for literature screening, data extraction and quality evaluation respectively. Meta-analysis was performed with RevMan 5.2 software. Funnel plot was used to analyze the publication bias., Results: A total of 4 RCTs were enrolled and 643 patients were included (325 in experimental group and 318 in control group). Meta-analysis showed that the tracheal reintubation rate in experimental group was lower than that in control group [odds ratio (OR) = 0.26, 95% confidence interval (95%CI) = 0.09-0.74, P = 0.01], but there was no significant difference in RAS [mean difference (MD) = -0.15, 95%CI = -0.50-0.21, P = 0.41] and the length of ICU stay (MD = 0.09, 95%CI = -0.09-0.26, P = 0.33) between experimental group and control group. Sensitivity analysis was performed in two trials with low risk of bias, which demonstrated that there was no significant difference in RAS between the two groups (MD = 0.06, 95%CI = -0.26-0.37, P = 0.73). It was shown by the funnel analysis that there was bias in the study of the length of ICU stay in the literature, while the bias of RAS and tracheal reintubation rate was low., Conclusions: Compared with COT, HFNC could reduce the rate of tracheal reintubation in adults after cardiac surgeries, but no difference was found in improving atelectasis or reducing the length of ICU stay.

Objective: To investigate the diagnostic value of TruScreen (TS) as a novel option for cervical lesions screening., Methods: A total of 218 cases were selected between 2013 December and 2014 November from outpatients of the Department of Gynecology, PLA General Hospital. Using histopathology as the gold standard for diagnosis, the diagnostic efficacy of TS was compared with that of high-risk human papillomavirus (Hr-HPV) test., Results: (1) In 218 patients, there were 193 Hr-HPV positive cases accounting for 88.5%, 94 TS positive cases accounting for 43.1%. According to the histopathology, there were 112 cases of cervical intraepithelial neoplasia (CIN)1+, 71 cases of CIN2+, accounting for 51.4% and 32.6%, respectively. (2) The sensitivity of Hr-HPV was 98.2% and specificity was 21.7%. The sensitivity of TS was 51.8% and specificity 66.0%. (3) Sensitivity of TS for triaging cases of atypical squamous cells of undetermined signification (ASC-US) was 43.9%, specificity 65.7%, diagnostic accordance rate 53.9%. Those indexes for triaging cases of equivalent or more than atypical squamous cells-cannot exclude high-grade squamous intraepithelial lesion (ASC-H) were 56.3%, 66.2% and 61.3%. With regard to Hr-HPV test, those indexes for triaging cases of equivalent or more than ASC-H were 97.2%, 32.4% and 64.8%., Conclusions: Hr-HPV test shows higher sensitivity while TruScreen shows higher specificity for cervical lesions screening. More studies with larger sample size are still needed to evaluate which method is a better triage tool.

Background and Objective: It has been proven that increase of the awareness level of lung cancer prevention and control could enhance participation of lung cancer screening of lung cancer high risk group. The aim of this study is to investigate the awareness level of lung cancer prevention and control and the effect of individual characteristics on lung cancer awareness, and to provide evidence for comprehensive lung cancer prevention in high risk areas of lung cancer., Methods: Staffs of Tianjin Dagang Oil Field who participate low dose CT (LDCT) lung cancer screening by cluster sampling or according to voluntary principle were surveyed, data of lung cancer awareness were collected by questionnaire., Results: A total of 1,633 valid questionnaires were collected. The average age of respondents was 60.08±6.58. Most participants were males (82.2%) while female only accounted for 17.8%. The proportions of awareness about lung cancer in China, risk factors, screening methods and the knowledge of health examination were 64.5%, 77.1%, 43.7%, 49.6% respectively. Result of multiple logistic regression analysis showed that education level, smoking (pack-year), age, prior tuberculosis were the influencing factors of lung cancer awareness with adjusted Ors for education and age level as of 0.567 (95%CI: 0.439-0.733) and 1.373 (95%CI: 1.084-1.739) respectively. 80.3% of the participants can accept health examination once a year, while the ability to pay the medical expenses was not high. The influencing factors of health examination willingness were gender, age, income, the knowledge of lung cancer., Conclusions: Education level and smoking affect the awareness of lung cancer prevention and control, health education for lung cancer should be conducted especially in population with low education level. Comprehensive lung cancer control in high risk areas should combined lung cancer screening, tobacco control and health education.

Background and Objective: BAG genes (Bcl-2-associated athanogene) belong to a recently discovered multifunctional anti-apoptosis gene family that regulate various physiological processes which include apoptosis, tumorigenesis, neural differentiation, stress response and cell cycle and so on. The expression status of BAG family genes are related to certain tumor incidence and prognosis. The aim of this study is to explore the association of the BAG family gene expression status with the susceptibility of lung adenocarcinoma., Methods: The gene expression data of BAG family genes from 29 cases of lung adenocarcinoma tissues and matched pericancerous lung tissues were generated by microarray chips. Cox regression was used to analyze the association between the expression of BAG family genes and the susceptibility of lung adenocarcinoma and the results were verified by GEO database., Results: The expression levels of BAG-1, BAG-2, BAG-5 in cancer tissues were significantly downregulated compared with matched pericancerous lung tissues and were protective factors of lung adenocarcinoma (P < 0.05, OR < 1); while the expression level of BAG-4 in cancer tissues were remarkably upregulated compared with the matched pericancerous lung tissues and was risk factor of lung adenocarcinoma (P < 0.05, OR > 1)., Conclusions: BAG-1, BAG-2, BAG-5 might be the potential protective factors while BAG-4 is possible risk factor of lung adenocarcinoma.