Melatonin protects against COPD by attenuating apoptosis and endoplasmic reticulum stress via upregulating SIRT1 expression in rats

The apoptosis of bronchial and alveolar epithelial cells plays a key role in COPD. The endoplasmic reticulum (ER) stress induced by cigarette smoke contributes to apoptosis. Previous studies demonstrated that melatonin prevented the development of COPD. In addition, silent information regulator 1 (SIRT1) had a protective effect against COPD. However, it remains unclear whether SIRT1 is involved in the protection of melatonin against COPD. In this study, thirty-two male Wistar rats were randomly assigned to four groups: Control group, COPD group, COPD+Mel group and COPD+Mel+EX527 group. Rats were challenged with cigarette smoke and lipopolysaccharide with or without melatonin or EX527 (a selective inhibitor of SIRT1). The lung histopathology, apoptotic index as well as the protein expressions of cleaved caspase-3, SIRT1, CHOP and caspase-12 in the lung tissues were measured. These results demonstrated that melatonin attenuated apoptosis and ER stress in the lung tissues of rats with COPD. In addition, melatonin increased SIRT1 expression in lung tissues of rats with COPD, while inhibition of SIRT1 by EX527 upregulated ER stress and abolished the protective effect of melatonin against apoptosis. In conclusion, these findings suggested that melatonin protected against COPD by attenuating apoptosis and ER stress via upregulating SIRT1 expression in rats.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Using Lidar technology to assess regional air pollution and improve estimates of PM2.5 transport in the North China Plain

Air pollutants seriously impact climate change and human health. In this study, the gridpoint statistical interpolation (GSI) three-dimensional variational data assimilation system was extended from ground data to vertical profile data, which reduced the simulation error of the model in the vertical layer. The coupled GSI-Lidar-WRF-Chem system was used to improve the accuracy of fine particulate matter (PM _2.5 ) simulation during a wintertime heavy pollution event in the North China Plain in late November 2017. In this experiment, two vehicle-mounted Lidar instruments were utilized to make synchronous observations around the 6th Ring Road of Beijing, and five ground-based Lidars were used for long-term network observations on the North China Plain. Data assimilation was then performed using the PM _2.5 vertical profile retrieved from the seven Lidars. Compared with the model results, the correlation of assimilation increased from 0.74–0.86, and the root-mean-square error decreased by 36.6%. Meanwhile, the transport flux and transport flux intensity of the PM _2.5 were analyzed, which revealed that the PM _2.5 around the 6th Ring Road of Beijing was mainly concentrated below 1.8 km, and there were obvious double layers of particles. Particulates in the southwest were mainly input, while those in the northeast were mainly output. Both the input and output heights were around 1 km, although the input intensity was higher than the output intensity. The GSI-Lidar-WRF-Chem system has great potential for air quality simulation and forecasting

Functional Nanoclay Suspension for Printing-Then-Solidification of Liquid Materials

Additive manufacturing (AM) enables the freeform fabrication of complex structures from various build materials. The objective of this study is to develop a novel Laponite nanoclay-enabled “printing-then-solidification” additive manufacturing approach to extrude complex three-dimensional (3D) structures made of various liquid build materials. Laponite, a member of the smectite mineral family, is investigated to serve as a yield-stress support bath material for the extrusion printing of liquid build materials. Using the printing-then-solidification approach, the printed structure remains liquid and retains its shape with the help of the Laponite support bath. Then the completed liquid structures are solidified in situ by applying suitable cross-linking mechanisms. Finally, the solidified structures are harvested from the Laponite nanoclay support bath for any further processing as needed. Due to its chemical and physical stability, liquid build materials with different solidification/curing/gelation mechanisms can be fabricated in the Laponite bath using the printing-then-solidification approach. The feasibility of the proposed Laponite-enabled printing-then-solidification approach is demonstrated by fabricating several complicated structures made of various liquid build materials, including alginate with ionic cross-linking, gelatin with thermal cross-linking, and SU-8 with photo-cross-linking. During gelatin structure printing, living cells are included and the postfabrication cell viability is above 90%

Self-Supporting Nanoclay as Internal Scaffold Material for Direct Printing of Soft Hydrogel Composite Structures in Air

Three dimensional (3D) bioprinting technology enables the freeform fabrication of complex constructs from various hydrogels and is receiving increasing attention in tissue engineering. The objective of this study is to develop a novel self-supporting direct hydrogel printing approach to extrude complex 3D hydrogel composite structures in air without the help of a support bath. Laponite, a member of the smectite mineral family, is investigated to serve as an internal scaffold material for the direct printing of hydrogel composite structures in air. In the proposed printing approach, due to its yield-stress property, Laponite nanoclay can be easily extruded through a nozzle as a liquid and self-supported after extrusion as a solid. Its unique crystal structure with positive and negative charges enables it to be mixed with many chemically and physically cross-linked hydrogels, which makes it an ideal internal scaffold material for the fabrication of various hydrogel structures. By mixing Laponite nanoclay with various hydrogel precursors, the hydrogel composites retain their self-supporting capacity and can be printed into 3D structures directly in air and retain their shapes before cross-linking. Then, the whole structures are solidified in situ by applying suitable cross-linking stimuli. The addition of Laponite nanoclay can effectively improve the mechanical and biological properties of hydrogel composites. Specifically, the addition of Laponite nanoclay results in a significant increase in the Young’s modulus of each hydrogel–Laponite composite: 1.9-fold increase for the poly­(ethylene glycol) diacrylate (PEGDA)–Laponite composite, 7.4-fold increase for the alginate–Laponite composite, and 3.3-fold increase for the gelatin–Laponite composite

Climatic and Topographical Effects on the Spatiotemporal Variations of Vegetation in Hexi Corridor, Northwestern China

Oases, as complex geographical landscapes, are strongly influenced by both natural variation and human activities. However, they have degenerated because of unplanned land use and water resource development. The research of oasis changes has mostly discussed single components, but multiple components, especially spatial changes to oasis vegetation, need further strengthening. Land use and NDVI were extracted based on Landsat 5/8 and Mod13A3, respectively, and a transfer matrix was constructed to analyze changes of land use in the Hexi Corridor during 2000–2020. The significant changes in the area of each land use were also quantified. Combined with regional temperature and precipitation, interpolated from meteorological data, the correlations between regional temperature, precipitation, and vegetation coverage were calculated, especially in the quantized areas with significant associations. The results showed that the area of bare land or desert decreased, while the areas of agricultural and residential land increased. The normalized difference NDVI of the studied oases increased at the rate of 0.021 per decade, which was positively related to precipitation (p < 0.05), rather than temperature; of which, farmland and planted grass land were 55.65% and 33.79% in the significantly increased area. In the area of significant positive relation between NDVI and precipitation, the ratio of grassland, farmland, and forest was 79.21%, 12.82%, and 4.06%, respectively. Additionally, changes in oasis vegetation were determined primarily by agricultural activities, which reflected a combination of natural and anthropic influences

Spatiotemporal Variation of Snow Cover Frequency in the Qilian Mountains (Northwestern China) during 2000–2020 and Associated Circulation Mechanisms

Linking snow cover frequency (SCF) and atmospheric circulation is vital for comprehension of hemispheric-scale change mechanisms and for accurate forecasting. This study combined MODIS imagery with meteorological observations to investigate the variation of annual SCFs in the Qilian Mountains. Results indicated that more than 80% of annual SCF is distributed at high elevations and mostly on northern slopes, and that SCF is greater in the west than in the east. Abrupt change in the increase in annual SCF was not detected; however, significant (0.05 confidence level) variation with quasi-3-year and quasi-5-year periods indicated potential connection with monsoons. Topographically, SCF increased at high elevations and decreased in valleys. Moreover, SCF increased significantly with a rise in slope below 23° and then decreased between 23° and 45°, and it decreased with a change in aspect from 70° to 200° and then increased from 200° to 310°. Annual SCF variation in the Qilian Mountains is dominated by precipitation rather than by temperature. In the years with high SCFs, southeasterly winds associated with an anticyclone over southeastern China and southwesterly winds associated with the cyclone over the Iranian Plateau brought warm moisture across northwestern China, favoring snowfall in the Qilian Mountains. Meanwhile, cold moisture outbreaks from the Arctic into the mid-latitudes are conducive to maintaining snow cover. However, in the years with low SCFs, the cold air might be difficultly transporting out of the Arctic region due to the strengthening polar vortex. Moreover, the water vapor was less than that of the mean state and divergence over the Qilian Mountains, which difficultly conduced snowfall over the Qilian Mountains

Spatiotemporal Variation of Snow Cover Frequency in the Qilian Mountains (Northwestern China) during 2000&ndash;2020 and Associated Circulation Mechanisms

Linking snow cover frequency (SCF) and atmospheric circulation is vital for comprehension of hemispheric-scale change mechanisms and for accurate forecasting. This study combined MODIS imagery with meteorological observations to investigate the variation of annual SCFs in the Qilian Mountains. Results indicated that more than 80% of annual SCF is distributed at high elevations and mostly on northern slopes, and that SCF is greater in the west than in the east. Abrupt change in the increase in annual SCF was not detected; however, significant (0.05 confidence level) variation with quasi-3-year and quasi-5-year periods indicated potential connection with monsoons. Topographically, SCF increased at high elevations and decreased in valleys. Moreover, SCF increased significantly with a rise in slope below 23&deg; and then decreased between 23&deg; and 45&deg;, and it decreased with a change in aspect from 70&deg; to 200&deg; and then increased from 200&deg; to 310&deg;. Annual SCF variation in the Qilian Mountains is dominated by precipitation rather than by temperature. In the years with high SCFs, southeasterly winds associated with an anticyclone over southeastern China and southwesterly winds associated with the cyclone over the Iranian Plateau brought warm moisture across northwestern China, favoring snowfall in the Qilian Mountains. Meanwhile, cold moisture outbreaks from the Arctic into the mid-latitudes are conducive to maintaining snow cover. However, in the years with low SCFs, the cold air might be difficultly transporting out of the Arctic region due to the strengthening polar vortex. Moreover, the water vapor was less than that of the mean state and divergence over the Qilian Mountains, which difficultly conduced snowfall over the Qilian Mountains