Climate change, especially precipitation change, will significantly change soil moisture, which then influences root growth, further affecting yield and grain quality. Previous studies focused on the ...drought or flood effects on summer maize growth. However, few studied the effects of drought-flood abrupt alternation (DFAA) on the growth of summer maize. We explored the DFAA impacts on the roots, leaf area index (LAI), yield, and grain quality in field. The main results show that DFAA had different impacts on the summer maize growth in the seeding-jointing stage (SJS) and tasseling-grain filling stage (TGS). In general, the DFAA reduced the yield. Roots at the depth of 40 cm had obviously positive impacts on the yield. The DFAA reduced the LAI and promoted the maximum LAI achieving in advance. The grain crude protein augmented under DFAA. The drought had evidently negative impacts on the grain crude fat in the TGS, while it had no obvious influence in the SJS. DFAA had no apparent impact on the grain crude starch. These results could provide some references for the effects and adaptation-strategies study of extreme climate events and their impacts on growth of summer maize.
A COVID-19 outbreak in the rural areas of Shijiazhuang City was attributed to the complex interactions among vaccination, host, and non-pharmaceutical interventions (NPIs). Herein, we investigated ...the epidemiological characteristics of all reported symptomatic cases by picking Shijiazhuang City, Hebei Province in Northern China as research objective. In addition, we established a with age-group mathematical model to perform the optimal fitting and to investigate the dynamical profiles under three scenarios.
All reported symptomatic cases of Shijiazhuang epidemic (January 2-February 3, 2021) were investigated in our study. The cases were classified by gender, age group and location, the distributions were analyzed by epidemiological characteristics. Furthermore, the reported data from Health Commission of Hebei Province was also analyzed by using an age-group mathematical model by two phases and three scenarios.
Shijiazhuang epidemic caused by SARS-CoV-2 wild strain was recorded with the peak 84 cases out of 868 reported symptomatic cases on January 11, 2021, which was implemented with strong NPIs by local government and referred as baseline situation in this study. The research results showed that R0 under baseline situation ranged from 4.47 to 7.72, and Rt of Gaocheng Distinct took 3.72 with 95% confidence interval from 3.23 to 4.35 on January 9, the declining tendencies of Rt under baseline situation were kept till February 3, the value of Rt reached below 1 on January 19 and remained low value up to February 3 for Gaocheng District and Shijiazhuang City during Shijiazhuang epidemic. This indicated Shijiazhuang epidemic was under control on January 19. However, if the strong NPIs were kept, but remote isolation operated on January 11 was not implemented as of February 9, then the scale of Shijiazhuang epidemic reached 9482 cases from age group who were 60 years old and over out of 31,017 symptomatic cases. The investigation also revealed that Shijiazhuang epidemic reached 132,648 symptomatic cases for age group who were 60 years old and over (short for G2) under risk-based strategies (Scenario A), 58,048 symptomatic cases for G2 under late quarantine strategies (Scenario B) and 207,124 symptomatic cases for G2 under late quarantine double risk strategies (Scenario C), and that the corresponding transmission tendencies of Rt for three scenarios were consistently controlled on Jan 29, 2021. Compared with baseline situation, the dates for controlling Rt below 1 under three scenarios were delayed 10 days.
Shijiazhuang epidemic was the first COVID-19 outbreak in the rural areas in Hebei Province of Northern China. The targeted interventions adopted in early 2021 were effective to halt the transmission due to the implementation of a strict and village-wide closure. However we found that age group profile and NPIs played critical rules to successfully contain Shijiazhuang epidemic, which should be considered by public health policies in rural areas of mainland China during the dynamic zero-COVID policy.
In the water system, antibiotic pollution significantly impacts the human body and the environment. Therefore, it is essential to quickly identify the types of antibiotics in the system and detect ...their concentration. It has been reported that many metal ions interact with antibiotics, and some of them can also change the enzyme-like catalytic properties of gold clusters (AuNCs). In the experiments, we found significant differences in the experimental results when different antibiotics and metal ions were placed in a TMB-H2O2 system with AuNCs as catalysts. Based on this result, we devised a simple and sensitive colorimetric method for the simultaneous detection of multiple antibiotics using AuNCs-metal ions as the sensor, a multifunctional microplate detector as the detection instrument, and LDA as the analytical method. This method was successfully applied for the identification of antibiotics and the detection of their concentrations in river water.
Habitat quality has great significance in terms of regional ecological conservation and human welfare. In this study, we evaluated the spatial and temporal characteristics of land use and habitat ...quality in the temperate desert sub-region of the Ordos Plateau using patch-generating land use simulation (PLUS) and integrated valuation of ecosystem services and trade-offs (InVEST) models. From 2000 to 2020, the areas of grassland, cropland, and unused land in the study area increased significantly; the areas of water bodies and woodland increased slightly; and the area of wasteland decreased significantly. Moreover, the habitat quality in the temperate desert subzone of the Ordos Plateau showed a trend of initial increase and then decrease between 2000 and 2020. The areas of lower and low habitat quality first decreased and then increased, and the overall area decreased over time. Conversely, the areas of high and higher habitat quality initially increased and then decreased, and the overall area increased over time. The area of medium habitat quality first decreased and then increased, although the overall change was minimal. Based on the PLUS model, the predicted habitat quality of the study area in 2025 under the natural development scenario was compared to that predicted under the ecological conservation scenario. The comparison of results showed higher habitat quality and lower habitat degradation under the ecological conservation development scenario. These results can be used to provide a scientific basis and decision reference for the sustainable use of land resources and encouragement of high-quality socio-economic development in the temperate desert sub-region of the Ordos Plateau.
Gas shale has shown considerable force in gas production worldwide, but little attention has been paid to its electrical properties, which are essential for reservoir evaluation and differentiating ...absorbed gas and free gas. In this study, experiments are designed to research water saturation establishment methods and electrical properties of gas shale. Nuclear magnetic resonance (NMR) with short echo space (TE) is used to identify water saturation and distribution of saturated pores which contribute to the conductivity. The experimental results indicate that NMR with shorter TE can estimate porosity and fluid distribution better than NMR with longer TE. A full range of water saturation is established by the combination of new-type spontaneous imbibition and semi-permeable plate drainage techniques. Spontaneous imbibition gains water saturation from 0% to near irreducible water saturation, and, semi-permeable plate drainage desaturates from 100% to irreducible water saturation. The RI-Sw curve shows a nonlinear relationship, and can be divided into three parts with different behaviors. The comparative analysis of transverse relaxation time (T2) distribution and RI-Sw curves, indicates that free water, and water trapped by capillarity in the non-clay matrix, differ in terms of electrical conductivity from water absorbed in clay. The new experiments prove the applicability of imbibition, drainage and NMR in investigating electrical properties of gas shale and differentiating fluid distribution which makes contribution to conductivity.
Elevated triglycerides are associated with an increased risk of cardiovascular disease (CVD). Therefore, it is very important to understand the metabolism of triglyceride-rich lipoproteins (TRLs) and ...their atherogenic role in animal models. Using low-density lipoprotein receptor knockout (LDLR
−/−
) Syrian golden hamsters, this study showed that unlike LDLR
−/−
mice, when LDLR
−/−
hamsters were fed a high cholesterol high-fat diet (HFD), they had very high plasma levels of triglycerides and cholesterol. We found that LDLR
−/−
hamsters exhibited increased serum TRLs and the ApoB100 and 48 in these particles after being fed with HFD. Treatment with ezetimibe for 2 weeks decreased these large particles but not the LDL. In addition, ezetimibe simultaneously reduced ApoB48 and ApoE in plasma and TRLs. The expression of LRP1 did not change in the liver. These findings suggested that the significantly reduced large particles were mainly chylomicron remnants, and further, the remnants were mainly cleared by the LDL receptor in hamsters. After 40 days on an HFD, LDLR
−/−
hamsters had accelerated aortic atherosclerosis, accompanied by severe fatty liver, and ezetimibe treatment reduced the consequences of hyperlipidemia. Compared with the serum from LDLR
−/−
hamsters, that from ezetimibe-treated LDLR
−/−
hamsters decreased the expression of vascular adhesion factors in vascular endothelial cells and lipid uptake by macrophages. Our results suggested that in the LDLR
−/−
hamster model, intestinally-derived lipoprotein remnants are highly atherogenic and the inflammatory response of the endothelium and foam cells from macrophages triggered atherosclerosis. The LDL receptor might be very important for chylomicrons remnant clearance in the Syrian golden hamster, and this may not be compensated by another pathway. We suggest that the LDLR
−/−
hamster is a good model for the study of TRLs-related diseases as it mimics more complex hyperlipidemia.
•Thickness of gas hydrate stability zone is re-calculated.•Factors influencing the thickness of gas hydrate stability zone are listed.•Effect of gas composition on the thickness of gas hydrate ...stability zone is presented.•Production feasibility is discussed for permafrost gas hydrate and marine gas hydrate.
Naturally-occurring gas hydrate, either in deepwater continental margins or in permafrost regions, is a promising unconventional energy resource which has attracted a lot attention from governments and researchers. In this paper, we studied the phase behavior for methane hydrate and mixed-gas hydrate. Four permafrost hydrates and three marine hydrate deposits were selected for analysis. They were Messoyakha (Russia), Mount Elbert (Alaska), Mackezie (Canada), Qilian Mountain (China) in permafrost regions and Blake Ridge (West Coast of US), Shenhu (South China Sea), and Nankai Trough (Japan Sea) in deepwater continental margins. The thickness of the gas hydrate stability zone (GHSZ) was calculated and compared. Our results show that the thickness of the GHSZ in permafrost regions is 1.3 to 4.5 times thicker than that in marine regions due to three factors: lower mudline temperature, smaller geothermal gradients and higher percentage of non-methane gases. The ramifications are that both the gas initially-in-place and the gas production rate will likely be higher in the permafrost environment. In addition, like other unconventional reservoirs, sustained gas production from a gas hydrate reservoir will likely require constantly drilling new wells to replace declining production from existing wells. All these suggest that development of gas hydrate in deep marine environment may be cost prohibitive. On the other hand, the well cost and drilling challenges will be significantly lower in the onshore permafrost environment where the resource density is also higher. Consequently, we see more potential for commercial development of permafrost hydrates than marine hydrates.
Permeability is an important parameter that helps understand the gas mass transport behavior in tight porous media. However, measuring the permeability of tight porous media accurately is an arduous ...task. Gas flow differs from liquid flow in regards to high compressibility, slippage effect, and sometimes adsorption. Slippage effect can be significant when the pressure is low or the pore diameter is small. Increasing pressure eliminates the slippage effect; however, high pressure is not always achievable under lab or field production conditions. The measurement of permeability during gas flow in a porous media is also greatly affected by the adsorption-induced surface diffusion process. In this study, a combined experimental–mathematical method for determining the permeability of tight porous media was developed. Steady-state measurements were conducted to obtain methane flux under different pressures for shale and tight reservoirs. The apparent permeability and permeability without slippage were calculated. Using the measured parameters, a mathematical model was derived to determine the intrinsic permeability, and the viability was tested with experimental results. This work provides an alternative approach to estimate the permeability of tight porous media during the gas mass transport process by considering both the slippage effect and gas surface adsorption. Parameters in the model can be easily measured through experiments for low pressures. Experimental verification shows that the error of permeability estimation can be decreased by approximately 10%.
Apoptosis plays a crucial role in many biological processes and pathogenesis of various malignancies and diseases of the immune system. In this paper, we described a novel method for sensitive ...detection of drug-induced apoptosis by using fluorescence correlation spectroscopy (FCS). The principle of this method is based on the assay of DNA fragmentation in the process of the drug-induced apoptosis. FCS is a single molecule method, and it can be used for sensitive and selective assay of DNA fragmentation without separation. We first developed a highly sensitive method for characterization of DNA fragments using a home-built FCS system and SYBR Green I as fluorescent DNA-intercalating dye, and then established a model of drug-induced apoptosis using human pancreatic cancer cells and a drug lidamycin. Furthermore, FCS method established was used to directly detect the fragmentation of DNA extracted from apoptotic cells or in the apoptotic cell lysate. In FCS assay, the single-component model and the multiple-components model were used to fit raw FCS data. The characteristic diffusion time of DNA fragments was used as an important parameter to distinguish the apoptotic status of cells. The obtained data documented that the characteristic diffusion time of DNA fragments from apoptotic cells significantly decreased with an increase of lidamycin concentration, which implied that DNA fragmentation occurred in lidamycin-induced apoptosis. The FCS results are well in line with the data obtained from flow cytometer and gel electrophoresis. Compared to current methods, the method described here is sensitive and simple, and more importantly, our detection volume is less than 1 fL, and the sample requirement can easily be reduced to nL level using a droplets array technology. Therefore, our method probably becomes a high throughput detection platform for early detection of cell apoptosis and screening of apoptosis-based anticancer drugs.
PDF
