Numerical simulations of the impacts of mountain on oasis effects in arid Central Asia

The oases in the mountain-basin systems of Central Asia are extremely fragile. Investigating oasis effects and oasis-desert interactions is important for understanding the ecological stability of oases. However, previous studies have been performed only in oasis-desert environments and have not considered the impacts of mountains. In this study, oasis effects were explored in the context of mountain effects in the northern Tianshan Mountains (NTM) using the Weather Research and Forecasting (WRF) model. Four numerical simulations are performed. The def simulation uses the default terrestrial datasets provided by the WRF model. The mod simulation uses actual terrestrial datasets from satellite products. The non-oasis simulation is a scenario simulation in which oasis areas are replaced by desert conditions, while all other conditions are the same as the mod simulation. Finally, the non-mountain simulation is a scenario simulation in which the elevation values of all grids are set to a constant value of 300 m, while all other conditions are the same as in the mod simulation. The mod simulation agrees well with near-surface measurements of temperature, relative humidity and latent heat flux. The Tianshan Mountains exert a cooling and wetting effects in the NTM region. The oasis breeze circulation (OBC) between oases and the deserts is counteracted by the stronger background circulation. Thus, the self-supporting mechanism of oases originating from the OBC plays a limited role in maintaining the ecological stability of oases in this mountain-basin system. However, the mountain wind causes the cold-wet'' island effects of the oases to extend into the oasis-desert transition zone at night, which is beneficial for plants in the transition region

Improved atmospheric modelling of the oasis-desert system in Central Asia using WRF with actual satellite products

Because of the use of outdated terrestrial datasets, regional climate models (RCMs) have a limited ability to accurately simulate weather and climate conditions over heterogeneous oasis-desert systems, especially near large mountains. Using actual terrestrial datasets from satellite products for RCMs is the only possible solution to the limitation; however, it is impractical for long-period simulations due to the limited satellite products available before 2000 and the extremely time- and labor-consuming processes involved. In this study, we used the Weather Research and Forecasting (WRF) model with observed estimates of land use (LU), albedo, Leaf Area Index (LAI), and green Vegetation Fraction (VF) datasets from satellite products to examine which terrestrial datasets have a great impact on simulating water and heat conditions over heterogeneous oasis-desert systems in the northern Tianshan Mountains. Five simulations were conducted for 1-31 July in both 2010 and 2012. The decrease in the root mean squared error and increase in the coefficient of determination for the 2 m temperature (T2), humidity (RH), latent heat flux (LE), and wind speed (WS) suggest that these datasets improve the performance of WRF in both years; in particular, oasis effects are more realistically simulated. Using actual satellite-derived fractional vegetation coverage data has a much greater effect on the simulation of T2, RH, and LE than the other parameters, resulting in mean error correction values of 62%, 87%, and 92%, respectively. LU data is the primary parameter because it strongly influences other secondary land surface parameters, such as LAI and albedo. We conclude that actual LU and VF data should be used in the WRF for both weather and climate simulations

Agriculture intensification increases summer precipitation in Tianshan Mountains, China

The land-use and land-cover change has a significant impact on the climate at different spatio-temporal scales. In this study, we explored the long term oasis expansion effects on regional summer precipitation in the north slope of Tianshan Mountains, China using high-resolution regional climate model. The results indicate that the oasis expansion increases the summer precipitation in the middle Tianshan Mountains while it has only a small effect over the oasis regions itself. The results indicate further that the oasis expansion affects mainly the late afternoon summer convective precipitation. The advection of air with additional moisture from the oasis areas to the mountains due to the mountain/plain circulation system during the day triggers the orographic precipitation in the middle mountain regions. These new results indicate that the oasis expansion could attribute significantly to the recent finding from observational studies about the increasing trend of precipitation in the middle Tianshan Mountains

Numerical study of the interaction between oasis and urban areas within an arid mountains-desert system in Xinjiang, China

The rapid oasis expansion and urbanization that occurred in Xinjiang province (China) in the last decades have greatly modified the land surface energy balance and influenced the local circulation under the arid mountains-plain background system. In this study, we first evaluated the ALARO regional climate model coupled to the land surface scheme SURFEX at 4 km resolution using 53 national climatological stations and 5 automatic weather stations. We found that the model correctly simulates daily and hourly variation of 2 m temperature and relative humidity. A 4-day clear sky period has been chosen to study both local atmospheric circulations and their mutual interaction. Observations and simulations both show that a low-level divergence over oasis appears between 19:00 and 21:00 Beijing Time when the background mountain-plain wind system is weak. The model simulates a synergistic interaction between the oasis-desert breeze and urban-rural breeze from 16:00 until 22:00 with a maximum effect at 20:00 when the downdraft over oasis (updraft over urban) areas increases by 0.8 (0.4) Pa/s. The results show that the oasis expansion decreases the nocturnal urban heat island in the city of Urumqi by 0.8 degrees C, while the impact of urban expansion on the oasis cold island is negligible

Imaging receptor for advanced glycation end product expression in mouse model of hind limb ischemia

Background: The purpose of this study is to image the effect of diabetes on expression of receptor for advanced glycation endproducts (RAGE) in limb ischemia in live animals. Methods: Male wild-type C57BL/6 mice were either made diabetic or left as control. Two months later, diabetic and non-diabetic mice underwent left femoral artery ligation. The right leg served as lesion control. Five days later, mice were injected with 15.1 ± 4.4 MBq 99mTc-anti-RAGE F(ab’)2 and 4 to 5 h later (blood pool clearance) underwent SPECT/CT imaging. At the completion of imaging, mice were euthanized, hind limbs counted and sectioned, and scans reconstructed. Regions of interest were drawn on serial transverse sections comprising the hind limbs and activity in millicuries summed and divided by the injected dose (ID). Quantitative histology was performed for RAGE staining and angiogenesis. Results: Uptake of 99mTc-anti-RAGE F(ab')2 as %ID × 10−3 was higher in the left (ischemic) limbs for the diabetic mice (n = 8) compared to non-diabetic mice (n = 8) (1.20 ± 0.44% vs. 0.49 ± 0.40%; P = 0.0007) and corresponded to less angiogenesis in the diabetic mice. Uptake was also higher in the right limbs of diabetic compared to non-diabetic animals (0.82 ± 0.33% vs. 0.40 ± 0.14%; P = 0.0004). Conclusions: These data show the feasibility of imaging and quantifying the effect of diabetes on RAGE expression in limb ischemia

Imaging VEGF receptor expression to identify accelerated atherosclerosis

Background: The biology of the vulnerable plaque includes increased inflammation and rapid growth of vasa vasorum, processes that are associated with enhanced vascular endothelial growth factor (VEGF)/ imaging receptors for VEGF (VEGFR) signaling and are accelerated in diabetes. This study was designed to test the hypothesis that VEGFRs in atherosclerotic plaques with a SPECT tracer scVEGF-PEG-DOTA/99mTc (scV/Tc) can identify accelerated atherosclerosis in diabetes. Methods: Male apolipoprotein E null (ApoE−/−) mice (6 weeks of age) were made diabetic (n = 10) or left as non-diabetic (n = 13). At 26 to 28 weeks of age, 5 non-diabetic mice were injected with functionally inactivated scV/Tc (in-scV/Tc) that does not bind to VEGF receptors, while 8 non-diabetic and 10 diabetic mice were injected with scV/Tc. After blood pool clearance, at 3 to 4 h post-injection, mice were injected with CT contrast agent and underwent SPECT/CT imaging. From the scans, regions of interest (ROI) were drawn on serial transverse sections comprising the proximal aorta and the percentage of injected dose (%ID) in ROIs was calculated. At the completion of imaging, mice were euthanized, proximal aorta explanted for gamma well counting to determine the percentage of injected dose per gram (%ID/g) uptake and immunohistochemical characterization. Results: The uptake of scV/Tc in the proximal aorta, calculated from SPECT/CT co-registered scans as %ID, was significantly higher in the diabetic mice (0.036  ± 0.017%ID) compared to non-diabetic mice (0.017  ± 0.005%ID; P  < 0.01), as was uptake measured as %ID/g in harvested aorta, 1.81  ± 0.50%ID/g in the diabetic group vs. 0.98  ± 0.25%ID/g in the non-diabetic group (P  < 0.01). The nonspecific uptake of in-scV/Tc in proximal aorta was significantly lower than the uptake of functionally active scV/Tc. Immunostaining of the atherosclerotic lesions showed higher expression of VEGFR-1 and VEGFR-2 in the diabetic mice. Conclusion: These initial results suggest that imaging VEGFR with scV/Tc shows promise as a non-invasive approach to identify accelerated atherosclerosis

The responses of the ecosystems in the Tianshan North Slope under multiple representative concentration pathway scenarios in the middle of the 21st Century

The arid ecosystem is fragile and sensitive to the changes in climate and CO2 concentration. Exploring the responses of the arid ecosystem to the changes under different representative concentration pathways (RCPs) is of particular significance for the sustainable development of the ecosystem. In this study, the dynamics of net primary productivity (NPP), evapotranspiration (ET), and water use efficiency (WUE) for arid ecosystems in Tianshan North Slope are explored by running the arid ecosystem model at 25 km resolution under RCP2.6, RCP4.5, and RCP8.5. The climate in Tianshan North Slope presents a wet-warming trend during 2006-2055 under each RCP scenario with temporal and spatial heterogeneity. In response to the changes in climate and CO2, the regional annual NPP and ET increased during 2006-2055 by a respectively maximum rate of 2.15 g C m(-2) year(-1) and 0.52 mm year(-1) under RCP8.5. Both the NPP and ET share a similar temporal and spatial heterogeneity with climate change. Different vegetation types respond differently to the changes under different RCP scenarios with increasing WUE. Under each RCP, the non-phreatophyte, phreatophyte, and grass are more sensitive to the changes than in the others, and the broadleaf forest and cropland are less sensitive to the changes

The Prevalence of Cryptosporidium spp. and Giardia duodenalis in Marmota himalayana (Rodentia: Sciuridae) in the Qinghai Tibetan Plateau area, China

Background: Cryptosporidium and Giardia are well-known important intestinal zoonotic pathogens that can infect various hosts and cause diarrhoeal diseases. We aimed to determine the epidemiological prevalence and molecular characterization of Cryptosporidium and Giardia species in Himalayan marmot (Marmota himalayana, class Marmota) in the Qinghai Tibetan Plateau Area of Qinghai Province, Northwest China. Methods: Overall, 243 Himalayan marmot fecal samples were collected in 2017 and in 2019 and a two-step nested PCR technique was performed to amplify the fragments of the SSU rRNA gene of Cryptosporidium and 18S ribosomal RNA gene of Giardia. Molecular characterization of Cryptosporidium was performed with the primary primers N-DIAGF2 and N-DIAGR2, the secondary primers CPB-DIAGF and CPB-DIAGR. Similarly, molecular characterization of Giardia was used the first primers Gia2029 and Gia2150c, the secondary primers RH11 and RH4. The positive PCR products were sequenced and the sequences were processed by Clustal Omega and BLAST. Phylogenetic analysis was achieved by NJ method in MEGA. Results: The infection rate of Cryptosporidium spp. and G. duodenalis was 4.9% (12/243) and 0.8% (2/243) in M. himalayana, respectively. Cryptosporidium spp. are characterized as novel genotypes Cryptosporidium marmot genotype I (n=3) and Cryptosporidium marmot genotype II (n=9); G. duodenalis assemblage A (n=2) was found in M. himalayana. Conclusion: This is the first report of Cryptosporidium spp. and G. duodenalis infections in M. himalayana in Qinghai of Northwest China. The results indicate the existence of Cryptosporidium species and G. duodenalis infections that may have a potential public health significance

Integrated Assessment of Heavy Metal Contamination in Sediments from a Coastal Industrial Basin, NE China

The purpose of this study is to investigate the current status of metal pollution of the sediments from urban-stream, estuary and Jinzhou Bay of the coastal industrial city, NE China. Forty surface sediment samples from river, estuary and bay and one sediment core from Jinzhou bay were collected and analyzed for heavy metal concentrations of Cu, Zn, Pb, Cd, Ni and Mn. The data reveals that there was a remarkable change in the contents of heavy metals among the sampling sediments, and all the mean values of heavy metal concentration were higher than the national guideline values of marine sediment quality of China (GB 18668-2002). This is one of the most polluted of the world’s impacted coastal systems. Both the correlation analyses and geostatistical analyses showed that Cu, Zn, Pb and Cd have a very similar spatial pattern and come from the industrial activities, and the concentration of Mn mainly caused by natural factors. The estuary is the most polluted area with extremely high potential ecological risk; however the contamination decreased with distance seaward of the river estuary. This study clearly highlights the urgent need to make great efforts to control the industrial emission and the exceptionally severe heavy metal pollution in the coastal area, and the immediate measures should be carried out to minimize the rate of contamination, and extent of future pollution problems

Rotating electrode methods and oxygen reduction electrocatalysts

Rotating disk electrode (RDE) and rotating ring-disk electrode (RRDE) techniques are one kind of the important and commonly used methods in electrochemical science and technology, particularly, in the fundamental understanding of electrochemical catalytic reaction mechanisms such as electrocatalytic oxygen reduction reaction (ORR). The kinetics and mechanisms of ORR catalyzed by both noble metal- and nonnoble metal-based electrocatalysts are the most important aspects in fuel cell and other ORR-related electrochemical technologies. Using RDE and RRDE to evaluate the activities of catalysts and their catalyzed ORR mechanisms is necessary and also one of the most feasible approaches in the development of ORR electrocatalysts.Peer reviewed: YesNRC publication: Ye