Two new triterpenoid saponins and two new goodyerosides isolated from the whole plant of Tournefortia sibirica.

Two new triterpenoid saponins (oleanolic acid 2ß-hydroxyl-3-O-ß-D-glucuronopyranoside-6'-O-buthyl ester (1) and oleanolic acid 2ß-hydroxyl-3-O-[ß-D-glucuronopyranosyl-6'-O-methylester]-28-O-ß-D-glucopyranoside (2)) and two new goodyerosides (4-methylenefuran-2(5H)-one (6'-O-vanilloyl)-ß-D-glucopyranoside (3), 3-hydroxy-2(5H)-furanone, 4-(6'-O-vanilloyl)-ß-D-glucopyranoside (4)), together with seven known compounds (5-11) were isolated from the whole plant of Tournefortia sibirica L. The chemical structures of the compounds were determined by spectroscopic analysis (1D and 2D NMR) and HR-ESI-MS. Compounds 1, 6 and 9 showed significant cytotoxicity towards A549, SK-Hep1 and HeLa cells, with IC50 values ranging from 1.68 ± 0.09 to 6.87 ± 0.13 µM.

Prevalence, distribution, and risk factors of bovine tuberculosis in dairy cattle in central China.

Bovine tuberculosis (bTB) is one of the priority epidemic diseases in dairy cattle in China. Continuous surveillance and evaluation of the control programs will help on improving the efficiency of bTB control policy. We designed this study to investigate both animal and herd level prevalence of bTB, as well as to determine the associated factors in dairy farms in Henan and Hubei provinces. A cross-sectional study was conducted from May 2019 to September 2020 in central China (Henan and Hubei provinces). We sampled 40 herds in Henan and six herds in Hubei via stratified systematic sampling and administrated a questionnaire consisting of 35 factors. A total of 4900 whole blood samples were collected from 46 farms, including 545 calves < six months old and 4355 cows ≥ six months old. This study demonstrated a high animal-(18.65%, 95% CI: 17.6-19.8) and herd-level (93.48%, 95%CI: 82.1-98.6) prevalence of bTB in dairy farms in central China. The Least Absolute Shrinkage and Selection Operator (LASSO) and negative binomial regression models showed that herd positivity was associated with the practice of introducing new animals (RR = 1.7, 95%CI: 1.0-3.0, p = 0.042), and changing the disinfectant water in the wheel bath at the farm entrance every three days or less (RR = 0.4, 95%CI: 0.2-0.8, p = 0.005) which reduced the odds of herd positivity. In addition, the result illustrated that testing cows with a higher age group (≥ 60 months old) (OR=1.57, 95%CI: 1.14-2.17, p = 0.006) and within the early stage of lactation (DIM=60-120 days, OR=1.85, 95%CI: 1.19-2.88, p = 0.006) and the later stage of lactation (DIM≥301 days, OR=2.14, 95%CI: 1.30-3.52, p = 0.003) could maximize the odds of detecting seropositive animals. Our results have plenty of benefit to improve bTB surveillance strategies in China and elsewhere in the world. The LASSO and the negative binomial regression models were recommended when dealing with high herd-level prevalence and high dimensional data in questionnaire-based risk studies.

Expansion of the Sahara Desert and shrinking of frozen land of the Arctic.

Expansion of the Sahara Desert (SD) and greening of the Arctic tundra-glacier region (ArcTG) have been hot subjects under extensive investigations. However, quantitative and comprehensive assessments of the landform changes in these regions are lacking. Here we use both observations and climate-ecosystem models to quantify/project changes in the extents and boundaries of the SD and ArcTG based on climate and vegetation indices. It is found that, based on observed climate indices, the SD expands 8% and the ArcTG shrinks 16% during 1950-2015, respectively. SD southern boundaries advance 100 km southward, and ArcTG boundaries are displaced about 50 km poleward in 1950-2015. The simulated trends based on climate and vegetation indices show consistent results with some differences probably due to missing anthropogenic forcing and two-way vegetation-climate feedback effect in simulations. The projected climate and vegetation indices show these trends will continue in 2015-2050.

Assessing aerosol indirect effect on clouds and regional climate of East/South Asia and West Africa using NCEP GFS.

Aerosols can act as cloud condensation nuclei and ice nuclei, resulting in changes in cloud droplet/particle number/size, and hence altering the radiation budget. This study investigates the interactions between aerosols and ice clouds by incorporating the latest ice clouds parameterization in an atmospheric general circulation model. The simulation shows a decrease in effective ice cloud crystal size corresponding to aerosol increase, referred to as the aerosol first indirect effect, which has not been comprehensively studied. Ice clouds with smaller particles reflect more shortwave radiation and absorb more infrared radiation, resulting in radiation change by 0.5-1.0 W/m2 at the top of the atmosphere (TOA). The TOA radiation field is also influenced by cloud cover change due to aerosol-induced circulation change. Such aerosol effects on precipitation highly depend on the existence of a deep convection system: interactions between aerosols and ice clouds create dipole precipitation anomalies in the Asian monsoon regions; while in West Africa, enhanced convections are constrained by anticyclone effects at high levels and little precipitation increase is found. We also conduct an experiment to assess interactions between aerosols and liquid clouds and compare the climatic effects with that due to ice clouds. Radiation and temperature changes generated by liquid clouds are normally 1-2 times larger than those generated by ice clouds. The radiation change has a closer relationship to liquid cloud droplet size than liquid cloud cover, in contrast with what we find for ice clouds.

Influence of Tibetan Plateau snow cover on East Asian atmospheric circulation at medium-range time scales.

The responses of atmospheric variability to Tibetan Plateau (TP) snow cover (TPSC) at seasonal, interannual and decadal time scales have been extensively investigated. However, the atmospheric response to faster subseasonal variability of TPSC has been largely ignored. Here, we show that the subseasonal variability of TPSC, as revealed by daily data, is closely related to the subsequent East Asian atmospheric circulation at medium-range time scales (approximately 3-8 days later) during wintertime. TPSC acts as an elevated cooling source in the middle troposphere during wintertime and rapidly modulates the land surface thermal conditions over the TP. When TPSC is high, the upper-level geopotential height is lower, and the East Asia upper-level westerly jet stream is stronger. This finding improves our understanding of the influence of TPSC at multiple time scales. Furthermore, our work highlights the need to understand how atmospheric variability is rapidly modulated by fast snow cover changes.

Influence of the Madden-Julian oscillation on Tibetan Plateau snow cover at the intraseasonal time-scale.

The Tibetan Plateau (TP), known as the third pole of the Earth, has snow cover with intraseasonal to decadal variability that affects weather and climate both inside and outside the TP. However, the factors that generate the TP snow cover (TPSC) anomalies at the intraseasonal time-scale are unclear. This report reveals the influence of the Madden‒Julian oscillation (MJO), which is the most dominant component of the tropical intraseasonal variability, on TPSC. We focus on wintertime snow cover over the central and eastern TP, where the intraseasonal variability is large. TPSC increases/decreases in the MJO phases 8‒1/4-5, when the eastward-propagating MJO suppressed/enhanced convection locates over the Maritime Continent. Such a change in TPSC leads to the most dominant positive/negative anomalies of TPSC in the following phases 2‒3/6‒7 due to the non-significant change of TPSC in these phases. There is anomalous moisture advection over the upstream of the TP caused by MJO-excited large-scale atmospheric circulation. The advection process generates the low-frequency eastward-propagating anomalous water vapour from upstream to the TP that influences precipitation and, eventually, TPSC.

West African monsoon decadal variability and surface-related forcings: Second West African Monsoon Modeling and Evaluation Project Experiment (WAMME II).

The second West African Monsoon Modeling and Evaluation Project Experiment (WAMME II) is designed to improve understanding of the possible roles and feedbacks of sea surface temperature (SST), land use land cover change (LULCC), and aerosols forcings in the Sahel climate system at seasonal to decadal scales. The project's strategy is to apply prescribed observationally based anomaly forcing, i.e., "idealized but realistic" forcing, in simulations by climate models. The goal is to assess these forcings' effects in producing/amplifying seasonal and decadal climate variability in the Sahel between the 1950s and the 1980s, which is selected to characterize the great drought period of the last century. This is the first multi-model experiment specifically designed to simultaneously evaluate such relative contributions. The WAMME II models have consistently demonstrated that SST forcing is a major contributor to the 20th century Sahel drought. Under the influence of the maximum possible SST forcing, the ensemble mean of WAMME II models can produce up to 60% of the precipitation difference during the period. The present paper also addresses the role of SSTs in triggering and maintaining the Sahel drought. In this regard, the consensus of WAMME II models is that both Indian and Pacific Ocean SSTs greatly contributed to the drought, with the former producing an anomalous displacement of the Intertropical Convergence Zone (ITCZ) before the WAM onset, and the latter mainly contributes to the summer WAM drought. The WAMME II models also show that the impact of LULCC forcing on the Sahel climate system is weaker than that of SST forcing, but still of first order magnitude. According to the results, under LULCC forcing the ensemble mean of WAMME II models can produces about 40% of the precipitation difference between the 1980s and the 1950s. The role of land surface processes in responding to and amplifying the drought is also identified. The results suggest that catastrophic consequences are likely to occur in the regional Sahel climate when SST anomalies in individual ocean basins and in land conditions combine synergistically to favor drought.

Regions of strong coupling between soil moisture and precipitation.

Previous estimates of land-atmosphere interaction (the impact of soil moisture on precipitation) have been limited by a lack of observational data and by the model dependence of computational estimates. To counter the second limitation, a dozen climate-modeling groups have recently performed the same highly controlled numerical experiment as part of a coordinated comparison project. This allows a multimodel estimation of the regions on Earth where precipitation is affected by soil moisture anomalies during Northern Hemisphere summer. Potential benefits of this estimation may include improved seasonal rainfall forecasts.