Pulmonary Transit Time Assessment by CEUS in Healthy Rabbits: Feasibility, and the Effects of UCAs Dilution Concentration.

To evaluate the inter-observer variability and the intra-observer repeatability of pulmonary transit time (PTT) measurement using contrast-enhanced ultrasound (CEUS) in healthy rabbits, and assess the effects of dilution concentration of ultrasound contrast agents (UCAs) on PTT. Thirteen healthy rabbits were selected, and five concentrations UCAs of 1:200, 1:100, 1:50, 1:10, and 1:1 were injected into the right ear vein. Five digital loops were obtained from the apical 4-chamber view. Four sonographers obtained PTT by plotting the TIC of right atrium (RA) and left atrium (LA) at two time points (T1 and T2). The frame counts of the first appearance of UCAs in RA and LA had excellent inter-observer agreement, with intra-class correlations (ICC) of 0.996, 0.988, respectively. The agreement of PTT among four observers was all good at five different concentrations, with an ICC of 0.758-0.873. The reproducibility of PTT obtained by four observers at T1 and T2 was performed well, with ICC of 0.888-0.961. The median inter-observer variability across 13 rabbits was 6.5% and the median variability within 14 days for 4 observers was 1.9%, 1.7%, 2.2%, 1.9%, respectively; The PTT of 13 healthy rabbits is 1.01 ± 0.18 second. The difference of PTT between five concentrations is statistically significant. The PTT obtained by a concentration of 1:200 and 1:100 were higher than that of 1:1, while there were no significantly differences in PTT of a concentration of 1:1, 1:10, and 1:50. PTT measured by CEUS in rabbits is feasible, with excellent inter-observer and intra-observer reliability and reproducibility, and dilution concentration of UCAs influences PTT results.

CD47 blockade reduces ischemia/reperfusion injury in murine heart transplantation and improves donor heart preservation.

BACKGROUND: Myocardial ischemia-reperfusion injury (MIRI) is an important cause of early dysfunction and exacerbation of immune rejection in transplanted hearts. The integrin-related protein CD47 exacerbates myocardial ischemia-reperfusion injury by inhibiting the nitric oxide signaling pathway through interaction with thrombospondin-1 (TSP-1). In addition, the preservation quality of the donor hearts is a key determinant of transplant success. Preservation duration beyond four hours is associated with primary graft dysfunction. We hypothesized that blocking the CD47-TSP-1 system would attenuate ischemia-reperfusion injury in the transplanted heart and, thus, improve the preservation of donor hearts. METHODS: We utilized a syngeneic mouse heart transplant model to assess the effect of CD47 monoclonal antibody (CD47mAb) to treat MIRI. Donor hearts were perfused with CD47mAb or an isotype-matched control immunoglobulin (IgG2a) and were implanted into the abdominal cavity of the recipients after being stored in histidine-tryptophan-ketoglutarate (HTK) solution at 4 °C for 4 h or 8 h. RESULTS: At both the 4-h and 8-h preservation time points, mice in the experimental group perfused with CD47mAb exhibited prolonged survival in the transplanted heart, reduced inflammatory response and oxidative stress, significantly decreased inflammatory cell infiltration, and fewer apoptosis-related biomarkers. CONCLUSION: The application of CD47mAb for the blocking of CD47 attenuates MIRI as well as improves the preservation and prognosis of the transplanted heart in a murine heart transplant model.

Experimental impacts of grazing on grassland biodiversity and function are explained by aridity.

Grazing by domestic herbivores is the most widespread land use on the planet, and also a major global change driver in grasslands. Yet, experimental evidence on the long-term impacts of livestock grazing on biodiversity and function is largely lacking. Here, we report results from a network of 10 experimental sites from paired grazed and ungrazed grasslands across an aridity gradient, including some of the largest remaining native grasslands on the planet. We show that aridity partly explains the responses of biodiversity and multifunctionality to long-term livestock grazing. Grazing greatly reduced biodiversity and multifunctionality in steppes with higher aridity, while had no effects in steppes with relatively lower aridity. Moreover, we found that long-term grazing further changed the capacity of above- and below-ground biodiversity to explain multifunctionality. Thus, while plant diversity was positively correlated with multifunctionality across grasslands with excluded livestock, soil biodiversity was positively correlated with multifunctionality across grazed grasslands. Together, our cross-site experiment reveals that the impacts of long-term grazing on biodiversity and function depend on aridity levels, with the more arid sites experiencing more negative impacts on biodiversity and ecosystem multifunctionality. We also highlight the fundamental importance of conserving soil biodiversity for protecting multifunctionality in widespread grazed grasslands.

Land use intensification alters the relative contributions of plant functional diversity and soil properties on grassland productivity.

Understanding the mechanisms of grassland productivity variation is critical for global carbon cycling and climate change mitigation. Heretofore, it is unknown how different environmental factors drive small-scale spatial variation in productivity, and whether land use intensification, one of the most important global changes, can regulate the processes that drive productivity change. Here we performed an 18-year exclosure experiment across six sites with high-intensity mowing/grazing history in northern China to examine the effects of land use intensification on plant functional diversity, soil properties, and their relative contributions to above-ground net primary productivity (ANPP). We found that plant functional diversity and soil properties contributed to the variation in ANPP both independently and equally in enclosed grasslands (plant diversity: 20.6%; soil properties: 19.5%). Intensive land use significantly decreased the Rao's quadratic entropy (RaoQ) and community-weighted mean value (CWM) of plant height, and further suppressed the contributions of plant functional diversity to ANPP. In contrast, intensive land use increased soil available N, P, pH, electrical conductivity, and homogeneity of soil available P, and strengthened their contributions to ANPP (31.5%). Our results indicate that high-intensity land use practices in grasslands decrease the role of plant functional diversity, but strengthen the effects of soil properties on productivity. We, therefore, suggest that plant functional diversity can be used effectively to boost productivity in undisturbed grasslands, while soil properties might be a more critical consideration for grassland management in an areas with increased land use.

The relative and combined effects of herbivore assemblage and soil nitrogen on plant diversity.

Plant diversity can be affected by both herbivore grazing and soil resources. However, it is unclear if the joint effects of herbivores and soil resources might vary with components of plant diversity. Here, we evaluated the relative and combined effects of herbivore assemblage and soil nitrogen (N) quantity and heterogeneity on the α and ß components of plant diversity in a grassland that was subjected to four years of grazing under differing herbivore assemblages (no grazing, cattle grazing, sheep grazing, and mixed grazing). We found that herbivore assemblage combined with soil N quantity explained 41% of the variation in plant α-diversity, while herbivore assemblage combined with soil N heterogeneity explained 15% of the variation in plant ß-diversity. The independent effects of herbivore assemblage explained more than those of soil N for both α- and ß-diversity (α-diversity: 12% vs. 4%; ß-diversity: 18% vs. 16%). We concluded that the effects of herbivores are stronger than those of soil N, and that grazing-induced changes in soil resources are important drivers of plant diversity change, especially α-diversity. Therefore, we suggest that managing herbivore species by accounting for the effects that their grazing can have on soil resources may be significant for plant diversity maintenance.

Composite-Structure Material Design for High-Energy Lithium Storage.

High-energy storage devices are in demand for the rapid development of modern society. Until now, many kinds of energy storage devices, such as lithium-ion batteries (LIBs), sodium-ion batteries (NIBs), and so on, have been developed in the past 30 years. However, most of the commercially exploited and studied active electrode materials of these energy storage devices possess a single phase with low reversible capacity or unsatisfied cycle stability. Continuous and extensive research efforts are made to develop alternative materials with a higher specific energy density and long cycle life by element doping or surface modification. A novel strategy of forming composite-structure electrode materials by introducing structure units has attracted great attention in recent years. Herein, based on previous publications on these composite-structure materials, some important scientific points focusing on the design of composite-structure materials for better electrochemical performances reveal the distinction of composite structures based on average and local structure analysis methods, and an understanding of the relationship between these interior composite structures and their electrochemical performances is discussed thoroughly. The lithiation/delithiation mechanism and the remaining challenges and perspectives for composite-structure electrode materials are also elaborated.

[Inhibitory Effect of Phenol on Phosphorus Removal Performance of an EBPR System].

An SBR reactor was operated to study the inhibitory effect of different concentrations of phenol (5, 10, 30, 50, 100, 150, and 200 mg·L-1) on the phosphorus removal performance of an EBPR system. The results showed that when the phenol concentration was no higher than 50 mg·L-1, the removal efficiencies of COD and PO43--P were above 85%. The system showed efficient pollutant removal performance. However, when phenol was higher than 100 mg·L-1, phosphorus removal performance of the reactor decreased drastically. When phenol concentration was 200 mg·L-1, the system lost phosphorus removal performance after only 22 cycles. The average COD removal efficiency dropped to 61.3%, and high removal performance recovery was not observed in the short term. Meanwhile, it was found that long-term dosing of phenol inhibited phosphorus removal of the sludge subjected to EBPR. Furthermore, the inhibition on aerobic phosphate uptake was greater than that on anaerobic phosphate release. In addition, the limited sludge bulking disappeared gradually owing to acclimation of the sludge to toxicity with a low phenol concentration (≤ 50 mg·L-1). However, high concentration of phenol induced sludge bulking was difficult to recover. The short-term impact experiments showed that effluent COD and phosphorus fluctuation caused by phenol could be recovered gradually by removing phenol, suggesting that the inhibitory effect of phenol on phosphorus removal was reversible.

[Phosphorus Removal Performance in EBPR System under Extra-low Dissolved Oxygen Condition].

Two sequencing batch reactors (SBRs) were operated with alternating anaerobic/oxic (An/O) for 127 days to study the phosphorus removal efficiency and process performance of the EBPR under different dissolved oxygen gradient. For the reactor (R1) in which DO was not controlled and measured as high as 6 mg·L-1 during the aerobic stage, a stable phosphorus removal performance was achieved in the former 65 days during the operational period. The phosphorus removal efficiency was greater than 95.9% and the total phosphorus in effluent was less than 0.5 mg·L-1. However, the phosphorus removal performance subsequently deteriorated after 65 days and completely broke up until 97 day due to long-term excessive aeration. Throughout the operational period,only 39.4% of effluent TP met the national wastewater discharge standard A. For the test reactor (R2) in which DO was controlled at the levels of 2, 1, 0.5, 0.2, 0.1 mg·L-1 during the aerobic stage, respectively, the phosphorus removal performance showed a slight fluctuation at the beginning of each stage but rapidly increased to a stable state. According to the statistics, 94.6% of effluent TP in reactor R2 could meet the national wastewater discharge standard A throughout the operational period. In only 6 days out of the 127 days, effluent TP failed to meet the national standard and the process performance was far better than that of R1. The specific phosphate uptake rate under DO=2 mg·L-1 was found to be nearly the maximum, but it was greatly influenced by the low DO. In addition, limited filamentous bulking resulted from low organic matter degradation rate under extra-low DO level (0.1 mg·L-1) was observed. Nevertheless, 100% of effluent TP during this stage could meet the national standard. As a result, the phosphorus removal in micro-aerobic EBPR system for saving energy was feasible.