Study on imbibition during the CO2 enhanced oil recovery in fractured tight sandstone reservoirs

CO2 enhanced oil recovery (CO2-EOR) is a key technology for improving the oil recovery of fractured tight reservoirs, and imbibition has been recognized as an important mechanism for oil recovery in low-permeability reservoirs. To clarify the imbibition role and influencing factors during the CO2-EOR process in fractured tight oil reservoirs and also improve the EOR mechanism, a high-temperature and high-pressure CO2 imbibition experiment was performed based on the nuclear magnetic resonance technology. The results show that high pressure and high permeability are beneficial to imbibition efficiency. The salinity of the imbibition fluid is not very sensitive to the imbibition recovery. In addition, the CO2 increases the imbibition speed and can also significantly improve the production rate and oil recovery. It is beneficial to increase the CO2 concentration to shorten the imbibition equilibrium time and enhance oil recovery. According to the results of the nuclear magnetic resonance study, although the nanopore can provide a greater imbibition force, the oil flow resistance is also larger, but CO2 can reduce the flow resistance of oil and be conducive to oil production in smaller pores. The inclusion of imbibition into the research category of CO2-EOR mechanism will be more in line with field practice and more scientific in fractured tight reservoirs, thus providing theoretical support for the development and improvement of the CO2-EOR technology.Document Type: Original articleCited as: Wang, Y., Shang, Q., Guo, J., Zhou, L. Study on imbibition during the CO2 enhanced oil recovery in fractured tight sandstone reservoirs. Capillarity, 2023, 7(3): 47-56. https://doi.org/10.46690/capi.2023.06.0

A Systematic Review of Xuezhikang, an Extract from Red Yeast Rice, for Coronary Heart Disease Complicated by Dyslipidemia

Objective. This systematic review aims to evaluate the benefit and side effect of Xuezhikang for coronary heart disease (CHD) complicated by dyslipidemia. Methods. All randomized clinical trials (RCTs) with Xuezhikang as a treatment for CHD combined with dyslipidemia were considered for inclusion. Data extraction and analyses and quality assessment were conducted according to the Cochrane standards. Results. We included 22 randomized trials. Xuezhikang showed significant benefit on the incidence of all-cause deaths, CHD deaths, myocardial infarction, and revascularization as compared with placebo based on conventional treatment for CHD. It remarkably lowered total cholesterol (TC), triglyceride (TG), and low-density lipoprotein-cholesterol (LDL-C) as compared with the placebo or inositol nicotinate group, which was similar to statins group. Xuezhikang also raised high-density lipoprotein cholesterol (HDL-C) compared to placebo or no intervention, which was similar to Inositol nicotinate and slightly inferior to statins. The incidence of adverse events did not differ between the Xuezhikang and control group. Conclusions. Xuezhikang showed a comprehensive lipid-regulating effect and was safe and effective in reducing cardiovascular events in CHD patients complicated by dyslipidemia. However, more rigorous trials with high quality are needed to give high level of evidence

The Effect of Sodium Tanshinone IIA Sulfate and Simvastatin on Elevated Serum Levels of Inflammatory Markers in Patients with Coronary Heart Disease: A Study Protocol for a Randomized Controlled Trial

Background. Coronary heart disease (CHD) due to atherosclerotic inflammation remains a significant threat to global health despite the success of the lipid-lowering, anti-inflammatory statins. Tanshinone IIA, a potent anti-inflammatory compound derived from Traditional Chinese Medicine (TCM), may be able to supplement statins by further reducing levels of circulating inflammatory markers correlated to cardiovascular risk. Here, we present the protocol of a randomized controlled trial (RCT) that will investigate the synergistic effect of sodium tanshinone IIA sulfate and simvastatin on reducing elevated inflammatory markers in patients with CHD. Participants: Seventy-two inpatients with confirmed CHD, elevated serum high-sensitivity C-reactive protein (Hs-CRP) level, and a TCM diagnosis of blood stasis syndrome will be enrolled and randomized 1 : 1 into the control or experimental group. Intervention. All subjects will receive a standard Western therapy including 20 mg simvastatin orally once per evening. Patients in the experimental group will additionally receive a daily 80 mg dose of sodium tanshinone IIA sulfate intravenously, diluted into 250 mL 0.9% NaCl solution. The treatment period will be 14 days. Outcomes. Primary outcome parameter: serum Hs-CRP level. Secondary outcome parameters: other circulating inflammatory markers (including IL-6, TNFα, VCAM-1, CD40, sCD40L, MCP-1, and MMP-9), improvement in symptoms of angina and blood stasis syndrome, and safety. This trial is registered with ChiCTR-TRC-12002361

Complex Networks Approach for Analyzing the Correlation of Traditional Chinese Medicine Syndrome Evolvement and Cardiovascular Events in Patients with Stable Coronary Heart Disease

This is a multicenter prospective cohort study to analyze the correlation of traditional Chinese medicine (TCM) syndrome evolvement and cardiovascular events in patients with stable coronary heart disease (CHD). The impact of syndrome evolvement on cardiovascular events during the 6-month and 12-month follow-up was analyzed using complex networks approach. Results of verification using Chi-square test showed that the occurrence of cardiovascular events was positively correlated with syndrome evolvement when it evolved from toxic syndrome to Qi deficiency, blood stasis, or sustained toxic syndrome, when it evolved from Qi deficiency to blood stasis, toxic syndrome, or sustained Qi deficiency, and when it evolved from blood stasis to Qi deficiency. Blood stasis, Qi deficiency, and toxic syndrome are important syndrome factors for stable CHD. There are positive correlations between cardiovascular events and syndrome evolution from toxic syndrome to Qi deficiency or blood stasis, from Qi deficiency to blood stasis, or toxic syndrome and from blood stasis to Qi deficiency. These results indicate that stable CHD patients with pathogenesis of toxin consuming Qi, toxin leading to blood stasis, and mutual transformation of Qi deficiency and blood stasis are prone to recurrent cardiovascular events

Features of visibility variation at Great Wall Station, Antarctica

The variation of visibility at Great Wall Station (GWS) was analyzed using manual observational data for the period of 1986 to 2012. Results show that the frequencies of occurrence of high (≥10 km) and low visibility (0―1 km) are 61.0% and 8.0%, respectively. Visibility at GWS shows an evident seasonal variation: The highest visibility between November and March, and the lowest visibility from June to October. Sea fog and precipitation are the main factors for low visibility during summer, whereas frequent adverse weather, such as falling snow, blowing snow, or blizzards, are responsible for low visibility in winter. The frequency of occurrence of low visibility has decreased significantly from 1986 to 2012. Conversely, the frequency of occurrence of high visibility has shown a significant increasing trend, especially during winter. The decreasing tendencies of fog, blowing snow, and snowfall have contributed to the increasing trend of high visibility during winter. Visibility at GWS exhibits significant synoptic-scale (2.1 to 8.3 d), annual, and inter-annual periods (2 a, 4.1 a, and 6.9 a to 8.2 a), among which the most significant period is 4.1 a. The visibility observed during 2012 indicates that instrumental observation can be applied in the continuous monitoring of visibility at GWS

Oral Panax notoginseng

This systematic review aims to evaluate current evidence for the benefit and side effect of oral Panax notoginseng preparation for coronary heart disease (CHD). We included 17 randomized clinical trials (17 papers and 1747 participants). Comparing with no intervention on the basis of conventional therapy, oral Panax notoginseng did not show significant effect on reducing cardiovascular events, but it could alleviate angina pectoris (including improving the symptoms of angina pectoris [RR 1.20; 95% CI 1.12 to 1.28; 7 trials, n=791], improving electrocardiogram [RR 1.35; 95% CI 1.19 to 1.53; 8 trials, n=727], decreasing the recurrence of angina pectoris [RR 0.38; 95% CI 0.16 to 0.94; 1 trials, n=60], duration of angina pectoris [RR −1.88; 95% CI −2.08 to −1.69; 2 trials, n=292], and dosage of nitroglycerin [MD −1.13; 95% CI −1.70 to −0.56; 2 trials, n=212]); oral Panax notoginseng had no significant difference compared with isosorbide dinitrate on immediate effect for angina pectoris [RR 0.96; 95% CI 0.81 to 1.15; 1 trial, n=80]. In conclusion, oral Panax notoginseng preparation could relieve angina pectoris related symptoms. However, the small sample size and potential bias of most trials influence the convincingness of this conclusion. More rigorous trials with high quality are needed to give high level of evidence, especially for the potential benefit of cardiovascular events

Traditional Medicine in China, Korea, and Japan: A Brief Introduction and Comparison

Background and Purpose. Traditional medicine (TM) has been widely used in China (including the Taiwan region), Korea, and Japan. The purposes of this paper are to summarize the basic data on TM systems in these three countries and to compare them in terms of overall policy, education, and insurance. Methods. Government websites, national statistics, and authoritative papers from each country were fully searched. Further data were gathered by TM experts from each country. Results. China and Korea showed similar patterns in TM systems, whereas Japan showed different patterns. In China and Korea, TM was practiced in a dual system with conventional medicine (CM), and TM education was 6-year training programs on average for TM doctors, and acupuncture, moxibustion, and cupping were completely insured. Whereas, CM was dominant in Japan, and TM was practiced by each health care worker who has received different TM education respectively, and main TM therapies were partially insured. Conclusions. TM was developed similarly or somewhat differently based on differences in cultural background and national policies in East Asia. We cautiously propose that this study could contribute to the development of TM and also be used for reference in complementary and alternative medicine systems

Crop Monitoring and Classification Using Polarimetric RADARSAT-2 Time-Series Data Across Growing Season: A Case Study in Southwestern Ontario, Canada

Multitemporal polarimetric synthetic aperture radar (PolSAR) has proven as a very effective technique in agricultural monitoring and crop classification. This study presents a comprehensive evaluation of crop monitoring and classification over an agricultural area in southwestern Ontario, Canada. The time-series RADARSAT-2 C-Band PolSAR images throughout the entire growing season were exploited. A set of 27 representative polarimetric observables categorized into ten groups was selected and analyzed in this research. First, responses and temporal evolutions of each of the polarimetric observables over different crop types were quantitatively analyzed. The results reveal that the backscattering coefficients in cross-pol and Pauli second channel, the backscattering ratio between HV and VV channels (HV/VV), the polarimetric decomposition outputs, the correlation coefficient between HH and VV channel ρHHVV, and the radar vegetation index (RVI) show the highest sensitivity to crop growth. Then, the capability of PolSAR time-series data of the same beam mode was also explored for crop classification using the Random Forest (RF) algorithm. The results using single groups of polarimetric observables show that polarimetric decompositions, backscattering coefficients in Pauli and linear polarimetric channels, and correlation coefficients produced the best classification accuracies, with overall accuracies (OAs) higher than 87%. A forward selection procedure to pursue optimal classification accuracy was expanded to different perspectives, enabling an optimal combination of polarimetric observables and/or multitemporal SAR images. The results of optimal classifications show that a few polarimetric observables or a few images on certain critical dates may produce better accuracies than the whole dataset. The best result was achieved using an optimal combination of eight groups of polarimetric observables and six SAR images, with an OA of 94.04%. This suggests that an optimal combination considering both perspectives may be valuable for crop classification, which could serve as a guideline and is transferable for future research.This research was funded in part by the National Natural Science Foundation of China (Grant No. 41,804,004, 41,820,104,005, 41,531,068, 41,904,004), the Canadian Space Agency SOAR-E Program (Grant No. SOAR-E-5489), the Fundamental Research Funds for the Central Universities, China University of Geosciences (Wuhan) (Grant No. CUG190633), and the Spanish Ministry of Science, Innovation and Universities, State Research Agency (AEI) and the European Regional Development Fund under project TEC2017-85244-C2-1-P

Evaluation of reanalysis and satellite-based sea surface winds using in situ measurements from Chinese Antarctic Expeditions

Sea surface winds from reanalysis (NCEP-2 and ERA-40 datasets) and satellite-based products (QuikSCAT and NCDC blended sea winds) are evaluated using in situ ship measurements from the Chinese National Antarctic Research Expeditions (CHINAREs) from 1989 through 2006, with emphasis on the Southern Ocean (south of 45°S). Compared with ship observations, the reanalysis winds have a positive mean bias (0.32 m∙s-1 for NCEP-2 and 0.13 m∙s-1 for ERA-40), and this bias is more pronounced in the Southern Ocean (0.57 m∙s-1 and 0.45 m∙s-1, respectively). However, mean biases are negative in the tropics and subtropics. The satellite-based winds also show positive mean biases, larger than those of the reanalysis data. All four wind products overestimate ship wind speed for weak winds (10 m∙s-1). Differences between the reanalysis and satellite winds are examined to identify regions with large discrepancies