Composition and structure of extraction residue of direct coal liquefaction residue and recycle of active phase of iron catalyst

In order to solve the problem of iron source supply for large-scale direct liquefaction catalyst, and meanwhile realize the harmless separated-utilization of extraction residue from coal liquefaction, this paper conducted a research on the recovery of iron catalyst from extraction residue, and explored the feasibility of enriching recovery of iron catalyst by using physical magnetic separation method. Firstly, the characterization methods, such as particle size analysis, XRF, XRD, SEM, TG, SEM-EDX, were used to comprehensively characterize and analyze the physical and chemical properties of the extraction residue, and therefore determine the contents and existence forms of iron catalyst. From the results analysis, it can be seen that the extraction residue from industrial equipment is mainly composed of carbon in unreacted coal and residual carbon, volatile matter and ash, with uniform particle size and no agglomeration. The mass fraction of iron is 5.96%, and the iron species still exist as the active phase of paramagnetic Fe1−xS, which doped and coated by unreacted coal and residual asphalt, and uniformly mixed and distributed in the extracts with various elements such as Ca, Si, Al, O, etc. On this basis, four types of magnetic separation equipment were selected for magnetic separation enrichment under different magnetic field strengths, and the enriched samples were then used as catalysts for direct coal liquefaction reaction to investigate their performances in direct liquefaction reaction. The experimental results show that：On the one hand, the high gradient magnetic force generated by the wet vertical ring pulsating high gradient magnetic separator is applied to the magnetic catalyst fine powder. Together with using water as dispersion medium and washing medium, the fine separation of iron catalyst powder from extraction residue was realized more effectively. With the magnetic field strength of 640 000 A/m, the material enrichment rate of the iron-containing catalyst was 10.48%, and the mass fraction of iron was 11.37%, the extraction oil yield of high-pressure autoclave 41.96%, which was 7.17% higher than that without the catalyst, and 8.99% higher than that with the extraction residue. It can be mixed into fresh catalyst to achieve an effective reuse, to some extent solving the problem of catalyst iron source shortage

Microstructure Evolution of AlSi10Mg(Cu) Alloy Related to Isothermal Exposure

The mechanical properties and corrosion resistance changes of AlSi10Mg(Cu) alloy under different isothermal exposure conditions have been investigated by tensile experiments and electrochemical testing. The results show that isothermal exposure has a significant influence on the mechanical properties and corrosion resistance. Tensile strength is more sensitive to the higher exposure temperature, while the corrosion resistance is greater affected by the lower exposure temperature and shorter time. Microstructure evolution of AlSi10Mg(Cu) alloy related to different isothermal exposure condition has also been studied by using transmission electron microscopy (TEM). The results indicate that the isothermal exposure changed the type and density of nanoscale precipitates in the alloy, which in turn induced the change of performance of the alloy

Research on Methods of Active Steering Control Based on Receding Horizon Control

Active steering technology is a key technology for automatic driving vehicles to achieve route tracking and obstacle avoidance and risk avoidance, and its performance will affect the stability control of the vehicle. For solving the stability control issues of vehicles, which have uncertainty in model and robustness in system, this paper proposes an active steering control method based on the receding horizon control model. It calculates the optimal control law by this method by using the real-time vehicle state so that it can compensate for the uncertainty caused by model mismatch, interference, etc. The design of the controller is implemented by using the yaw rate deviation of the vehicle as the input of the receding horizon linear quadratic controller model and then inputting the calculated superposition angle into the vehicle model in real time. We built a Simulink control model to implement co-simulation with CarSim to verify the control effect of the controller. In addition, we built a steering hardware-in-the-loop platform based on the LabVIEW RT system. The experimental results show that the active steering system adopting a receding horizon control method had better system robustness and robust stability

Letrozole versus laparoscopic ovarian drilling in clomiphene citrate-resistant women with polycystic ovary syndrome: a systematic review and meta-analysis of randomized controlled trials

Abstract The objective of this systematic review was to examine the literature and to compare the effectiveness of letrozole (LE) versus laparoscopic ovarian drilling (LOD) for the induction of ovulation in women with clomiphene citrate (CC)-resistant polycystic ovary syndrome (PCOS). The PUBMED, Web of Science, and EMBASE databases were searched systematically for eligible randomized controlled trials (RCTs) from English language articles published from database inception to September 2018. Data were independently extracted and analyzed using the fixed-effects model or random-effects model according to the heterogeneity of the data. Four RCTs including 621 patients (309 in the LE group and 312 in the LOD group) met the inclusion criteria. There were no differences with regard to ovulation rate (relative risk [RR] 1.12; 95% confidence interval [CI] 0.93 to 1.34; P = 0.12, I2 = 90%, 541 patients, three studies), pregnancy rate (RR 1.21; 95% CI 0.95 to 1.53; P = 0.12, I2 = 0%, 621 patients, four studies), live birth rate (RR 1.27; 95% CI 0.96 to 1.68; P = 0.09, I2 = 19%, 541 patients, three studies), and abortion rate (RR 0.7; 95% CI 0.3 to 1.61; P = 0.40, I2 = 0%, 621 patients, four studies) between the two groups. These results indicated that LE and LOD appear to be equally effective in achieving live birth rate in patients with CC-resistant PCOS

Soil Enzyme Activity Differs among Native Species and Continuously Planted Eucalyptus Plantations

In recent years, monoculture and multi-rotation successional Eucalyptus plantations have given rise to several environmental issues, including the degradation of soil quality and nutrient imbalance, and the conversion of logging sites to multi-rotation Eucalyptus plantations has attracted considerable attention from the scientists involved. However, the effects of different management strategies on soil extracellular enzyme activities (EEAs) and enzyme stoichiometry (ES) in degraded Eucalyptus plantations are not clear. In this study, we investigated the responses and mechanisms of soil physicochemical properties, microbial biomass, carbon, and nitrogen- and phosphorus-acquiring enzyme activities, as well as the microbial resource requirements of Eucalyptus plantations, under different management strategies. The findings revealed that second-rotation (TWE) and third-rotation (THE) continuous plantings of pure Eucalyptus plantations resulted in significant decreases in soil organic carbon (SOC), total nitrogen (TN) and effective available phosphorus (AP) contents, while soil nutrient contents increased after the introduction of Manglietia glauca to form mixed forests (EM) with Eucalyptus or pure Manglietia glauca (M). Meanwhile, phosphorus-acquiring enzymes significantly increased with successive rotations of Eucalyptus (TWE and THE), while EEAC:P and EEAN:P gradually decreased and phosphorus limitation gradually increased compared to that of a native-species-mixed plantation (CK). After the introduction of Manglietia glauca (EM and M), phosphorus-acquiring enzyme activities showed lower levels and there were significant increases in EEAC:P and EEAN:P compared to those of continuous plantings of pure Eucalyptus plantations, which reduced microbial phosphorus demand. Moreover, soil nutrients played a more significant role in altering the EEAs and ES than did microbial biomass (0–10 cm: 72.7% > 53.3%, 10–20 cm: 54.5% > 32.6%). The results showed that EM and M improved soil fertility quality conditions and alleviated soil nutrient phosphorus limitations for soil microorganisms. Therefore, the introduction of Manglietia glauca, either to form mixed forests with Eucalyptus or in rotation with Eucalyptus, can be used as technical means for the conversion of multi-rotation successive Eucalyptus plantations

Association between recreational drug use and sexual practices among people who inject drugs in Southwest China:A cross-sectional study

Objective To describe the differences in sexual practices among individuals with various drug administration patterns. Setting A detoxification centre in Southwest China, a part of the Chinese national sentential surveillance network for hepatitis C virus (HCV), HIV and syphilis infections, was recruited. Participants A total of 610 newly enrolled injection drug users (IDUs) from detoxification centre were included during 2015. Primary and secondary outcome measures Self-reported sexual activities, drug-related practices and laboratory-confirmed HCV, HIV and syphilis infection status were collected. Results Of the 610 IDU, 295 (48.4%) used heroin only, 277 (45.4%) poly-drug users reported the mixed use of synthetic drugs (SDs) with heroin and 38 (6.2%) used SDs only. The average daily drug injection frequency for poly-drug users (3.3±1.2 times) was the highest, followed by heroin-only (2.2±0.8 times) and SD-only users (1.2±0.4 time). SD-only drug users reported the highest proportion (86.8%) of engaging in sexual activities in the previous month, with more than half (54.5%) reporting any condomless sex. A higher frequency of daily injecting in heroin-only users was significantly correlated with the less likelihood of sex, condomless sex in the past month, having sex with fixed partners, condomless commercial sex in the previous 12 months (all p0.05). Different patterns of HCV, HIV and syphilis infections prevalence rates were shown among the IDU depending on the roles and length of exposure. Conclusions The daily drug injecting frequency of heroin-only and poly-drug users was negatively associated with sexual activities, but SD-only users kept a high frequent engagement in sex. The interventions for relevant diseases should adapt to characteristics of IDU

Determining appropriate screening tools and cut-points for cognitive impairment in an elderly Chinese sample

The establishment of normative data and screening cut-points for cognitive tasks is important to ensure the effective and timely detection of mild cognitive impairment (MCI) and Alzheimer’s disease (AD). These need to be culturally relevant and account for known factors that impact on cognition such as age, education, and gender. In this study, 1,068 elderly Chinese residents of Shanghai completed a comprehensive series of cognitive tasks as part of a community screening study with 1027 meeting criteria for analysis, age M(SD) = 72.54 (8.40). MCI was detected in 267 individuals, AD in 50, and 710 had normal cognition. Receiver Operator Characteristic curve analysis indicated that the Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA) best differentiated normal cognition from MCI and AD. We present suggested cut-points to differentiate between normal cognition and MCI and AD for the total sample, and when split according to education levels, age, and gender. Trends suggest that the MoCA was better suited to detecting MCI, and the MMSE was better for detecting AD. For younger and more educated participants, only a slight impairment was necessary to meet screening criteria, while a larger impairment was necessary for older and less educated participants. Both tasks had a high negative predictive values for MCI and AD, and variable positive predictive values. The cut-points presented can be used to inform future work using the MMSE and MoCA to screen for MCI and AD in older Chinese people