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The karst region in southwestern China is particularly prominent and has become a core issue constraining ecological environment restoration and sustainable development in this area. This study utilized long-term remote sensing data to reveal the spatial pattern evolution characteristics of rocky desertification in the region in 2000, 2010, and 2020. Meanwhile, it analyzed the dynamic trend of vegetation coverage recovery in the area from 2000 to 2020, as well as the analysis of related factors. The results showed that the spatial distribution of the Normalized Difference Vegetation Index (NDVI) remained highly clustered, though the clustering gradually weakened over time. When NDVI exceeded 0.6, the probability of rocky desertification reversal increased. Currently, a core contradiction of “quantity increases but quality stagnates” exists in regional vegetation cover, characterized by a continuous rise in NDVI mean values coexisting with reduced spatial clustering. This phenomenon reflects the evolution of vegetation patterns under the combined effects of ecological engineering interventions, adjustments in human-land relationships, and constraints of karst landforms. Through factor analysis, slope and humidity were identified as key factors influencing vegetation restoration. The findings provide an important theoretical foundation and practical reference for targeted rocky desertification management, optimization of ecological restoration projects, and coordinated human-land development in karst regions.

The biophysical effects of vegetation changes are important in determining future climate changes using climate model. However, compared to observations, model has biases in energy exchange between vegetation and the lower atmosphere modulated by leaf area index and albedo. In this study, land-use induced anthropogenic influences, estimated as the differences between present land-use and idealized natural vegetation, on near-surface temperature were investigated using a regional climate model. Results show that present land-use transitions over China brings a cooler summer and winter accompanied by reduced diurnal temperature ranges by 0.11 °C and 0.25 °C respectively, which are mainly determined by the overwhelming increased evaporation and latent heat flux in summer and reduced net radiation in winter. Three vegetation pairs (i.e., forest and cropland, grassland and cropland, grassland and forest) were selected using observational datasets to evaluate vegetation induced climatic impact without atmospheric feedbacks across various climatic regimes. Albedo led absorbed radiation plays a dominate role in middle to north region while both LAI and albedo are significant below 30° N for latitudinal temperature changes between cropland and forest transitions. Model results have inconsistencies with observations on temperature trends caused by vegetation pairs, indicating summer cropland and forest over southern China is the most sensitive to the atmosphere conditions and forest and grassland pair is the least. These findings demonstrate the heterogeneous biophysical effect of vegetation in different climate zones and imply that a region-oriented parameterization of vegetation types should be applied in the land surface model to reduce uncertainties in future climate prediction.

Polymer scaffold systems consisting of poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) have proven to be possible matrices for the three-dimensional growth of chondrocyte cultures. However, the engineered cartilage grown on these PHBV scaffolds is currently unsatisfactory for clinical applications due to PHBV's poor hydrophilicity, resulting in inadequate thickness and poor biomechanical properties of the engineered cartilage. It has been reported that the incorporation of Bioglass (BG) into PHBV can improve the hydrophilicity of the composites. In this study, we compared the effects of PHBV scaffolds and PHBV/BG composite scaffolds on the properties of engineered cartilage in vivo. Rabbit articular chondrocytes were seeded into PHBV scaffolds and PHBV/BG scaffolds. Short-term in vitro culture followed by long-term in vivo transplantation was performed to evaluate the difference in cartilage regeneration between the cartilage layers grown on PHBV and PHBV/BG scaffolds. The results show that the incorporation of BG into PHBV efficiently improved both the hydrophilicity of the composites and the percentage of adhered cells and promoted cell migration into the inner part the constructs. With prolonged incubation time in vivo, the chondrocyte-scaffold constructs in the PHBV/BG group formed thicker cartilage-like tissue with better biomechanical properties and a higher cartilage matrix content than the constructs in the PHBV/BG group. These results indicate that PHBV/BG scaffolds can be used to prepare better engineered cartilage than pure PHBV.

Cartilage regeneration is still a challenge for clinicians because of avascularity, denervation, load-bearing, synovial movement, and the paucity of endogenous repair cells. We constructed a multilayered osteochondral bionic scaffold and examined its repair capacity using a rabbit osteochondral defect model. The cartilage phase and interface layer of the scaffold were prepared by freeze-drying, whereas the bone phase of the scaffold was prepared by high-temperature sintering. The three-phase osteochondral bionic scaffold was formed by joining the hydroxyapatite (HAp) and silk fibroin (SF) scaffolds using the repeated freeze-thaw method. Different groups of scaffolds were implanted into the rabbit osteochondral defect model, and their repair capacities were assessed using imaging and histological analyses. The cartilage phase and the interface layer of the scaffold had a pore size of 110.13±29.38 and 96.53±33.72 μm, respectively. All generated scaffolds exhibited a honeycomb porous structure. The polydopamine- (PDA-) modified scaffold released platelet-derived growth factor (PDGF) for 4 weeks continuously, reaching a cumulative release of 71.74±5.38%. Synovial mesenchymal stem cells (SMSCs) adhered well to all scaffolds, but demonstrated the strongest proliferation ability in the HSPP (HAp-Silk-PDA-PDGF) group. Following scaffold-induced chondrogenic differentiation, SMSCs produced much chondrocyte extracellular matrix (ECM). In in vivo experiments, the HSPP group exhibited a significantly higher gross tissue morphology score and achieved cartilage regeneration at an earlier stage and a significantly better repair process compared with the other groups (P<0.05). Histological analysis revealed that the new cartilage tissue in the experimental group had a better shape and almost filled the defect area, whereas the scaffold was nearly completely degraded. The new cartilage was effectively fused with the surrounding normal cartilage, and a substantial amount of chondrocyte ECM was formed. The SF/HAp three-layer osteochondral bionic scaffold exhibited favorable pore size, porosity, and drug sustained-release properties. It demonstrated good biocompatibility in vitro and encouraging repair effect at osteochondral defect site in vivo, thereby expected to enabling the repair and regeneration of osteochondral damage.

Interaction of anthropogenic particles with radiation and clouds plays an important role in Arctic climate change. The mixing state of aerosols is a key parameter to influence aerosol radiation and aerosol–cloud interactions. However, little is known of this parameter in the Arctic, preventing an accurate representation of this information in global models. Here we used transmission electron microscopy with energy-dispersive X-ray spectrometry, scanning electron microscopy, nanoscale secondary ion mass spectrometry, and atomic forces microscopy to determine the size and mixing state of individual sulfate and carbonaceous particles at 100 nm to 2 µm collected in the Svalbard Archipelago in summer. We found that 74 % by number of non-sea-salt sulfate particles were coated with organic matter (OM); 20 % of sulfate particles also had soot inclusions which only appeared in the OM coating. The OM coating is estimated to contribute 63 % of the particle volume on average. To understand how OM coating influences optical properties of sulfate particles, a Mie core–shell model was applied to calculate optical properties of individual sulfate particles. Our result shows that the absorption cross section of individual OM-coated particles significantly increased when assuming the OM coating as light-absorbing brown carbon. Microscopic observations here suggest that OM modulates the mixing structure of fine Arctic sulfate particles, which may determine their hygroscopicity and optical properties.

While titanium (Ti) implants have been extensively used in orthopaedic and dental applications, the intrinsic bioinertness of untreated Ti surface usually results in insufficient osseointegration irrespective of the excellent biocompatibility and mechanical properties of it. In this study, we prepared surface modified Ti substrates in which silicon (Si) was doped into the titanium dioxide (TiO2) nanotubes on Ti surface using plasma immersion ion implantation (PIII) technology. Compared to TiO2 nanotubes and Ti alone, Si-doped TiO2 nanotubes significantly enhanced the expression of genes related to osteogenic differentiation, including Col-I, ALP, Runx2, OCN, and OPN, in mouse pre-osteoblastic MC3T3-E1 cells and deposition of mineral matrix. In vivo, the pull-out mechanical tests after two weeks of implantation in rat femur showed that Si-doped TiO2 nanotubes improved implant fixation strength by 18% and 54% compared to TiO2-NT and Ti implants, respectively. Together, findings from this study indicate that Si-doped TiO2 nanotubes promoted the osteogenic differentiation of osteoblastic cells and improved bone-Ti integration. Therefore, they may have considerable potential for the bioactive surface modification of Ti implants.

Knowledge of aerosol size and composition is important for determining radiative forcing effects of aerosols, identifying aerosol sources and improving aerosol satellite retrieval algorithms. The ability to extrapolate aerosol size and composition, or type, from intensive aerosol optical properties can help expand the current knowledge of spatiotemporal variability in aerosol type globally, particularly where chemical composition measurements do not exist concurrently with optical property measurements. This study uses medians of the scattering Ångström exponent (SAE), absorption Ångström exponent (AAE) and single scattering albedo (SSA) from 24 stations within the NOAA/ESRL Federated Aerosol Monitoring Network to infer aerosol type using previously published aerosol classification schemes. Three methods are implemented to obtain a best estimate of dominant aerosol type at each station using aerosol optical properties. The first method plots station medians into an AAE vs. SAE plot space, so that a unique combination of intensive properties corresponds with an aerosol type. The second typing method expands on the first by introducing a multivariate cluster analysis, which aims to group stations with similar optical characteristics and thus similar dominant aerosol type. The third and final classification method pairs 3-day backward air mass trajectories with median aerosol optical properties to explore the relationship between trajectory origin (proxy for likely aerosol type) and aerosol intensive parameters, while allowing for multiple dominant aerosol types at each station. The three aerosol classification methods have some common, and thus robust, results. In general, estimating dominant aerosol type using optical properties is best suited for site locations with a stable and homogenous aerosol population, particularly continental polluted (carbonaceous aerosol), marine polluted (carbonaceous aerosol mixed with sea salt) and continental dust/biomass sites (dust and carbonaceous aerosol); however, current classification schemes perform poorly when predicting dominant aerosol type at remote marine and Arctic sites and at stations with more complex locations and topography where variable aerosol populations are not well represented by median optical properties. Although the aerosol classification methods presented here provide new ways to reduce ambiguity in typing schemes, there is more work needed to find aerosol typing methods that are useful for a larger range of geographic locations and aerosol populations

A heavy pollution episode (HPE) that lasted for seven days occurred over the North China Plain in December 2016. An in situ Ambient Ion Monitor was applied to analyze the chemical composition of PM 2.5 (fine particulate matter with diameters less than 2.5 µm) and gaseous HONO concentration during that event. A representative explosive growth in the pollution cumulative stage was selected to investigate the pollution mechanism during the HPE in Beijing. PM 2.5 cumulative explosive growth processes were observed to occur commonly under high relative humidity (RH) condition. Our results demonstrated that the aqueous-phase oxidation of SO 2 by NO 2 to sulfate could contribute to the cumulative explosive growth. Nitrate produced by secondary formation was another factor in the growth of PM 2.5. Depending on the relative humidity, temperature, and chemical species, the deliquescence relative humidity was calculated to 82%, 81%, and 83% for (NH 4 ) 2 SO 4 , NH 4 NO 3 , and NH 4 Cl, respectively. The preexisting PM 2.5 surface changed from solid to liquid when RH > 81%. Coincidentally, both the sulfur oxidation ratio (SOR) and reaction product HONO displayed an evident exponential relationship with RH and increased more quickly when RH was larger than 80%. In addition, sufficiently excessive NO 2 made the aqueous-phase oxidation of SO 2 efficiently proceed even at relative low SO 2 concentrations (below 15 µg m −3 ). Potential H + in the reactions was neutralized by NH 3 , resulting in fully neutralized PM 2.5 during HPE. The chemical evolution of these reactions was discussed in detail in this study.

High mobility group protein A2 (HMGA2) is a transcription factor that plays an important role in the invasion and metastasis of gastric carcinoma (GC). The term vasculogenic mimicry (VM) refers to the unique ability of aggressive tumour cells to mimic the pattern of embryonic vasculogenic networks. However, the relationship between HMGA2 and VM formation remains unclear. In the present study, we examined concomitant HMGA2 expression and VM in 228 human GC samples and 4 GC cell lines. Our data indicate that HMGA2 is not only significantly associated with VM formation but also influences the prognosis of patients with gastric carcinoma. Overexpression of HMGA2 significantly increased cell motility, invasiveness, and VM formation both in vitro and in vivo . A luciferase reporter assay, Co-IP and ChIP demonstrated that HMGA2 induced the expression of Twist1 and VE-cadherin by binding to the Twist1 promoter. Moreover, we observed a decrease in VE-cadherin following Twist1 knockdown in cells overexpressing HMGA2. This study indicates that HMGA2 promotes VM in GC via Twist1-VE-cadherin signalling and influences the prognosis of patients with GC.

Purpose: Chondrosarcoma is a malignancy affecting cartilage and is chemo- and radio-resistant. Novel immune checkpoint inhibitors may play a role in treatment; however, expression of programmed cell death ligand 1/2 (PD-L1/PD-L2) in chondrosarcoma is unreported. Methods: Chondrosarcoma sections were collected and stained immunohistochemically for PD-L1, PD-L2, Ki-67, and TP53. Clinicopathological parameters were collected and analyzed statistically for associations and correlations. PD-L1/PD-L2 positivity was designated using 1% and 5% cutoffs, respectively. Results: A total of 59 chondrosarcoma samples excised between 1997 and 2017 were collected. There were 40 samples assessed as PD-L1-positive and 25 samples as PD-L2-positive. In univariate analysis, PD-L1 positivity was significantly associated with younger age (P = .001), larger tumor (P = .025), advanced tumor grade (P < .001), and recurrence (P < .001). PD-L1 positivity was not associated with gender, location, serum level of lactate dehydrogenase, or serum level of alkaline phosphatase. PD-L2 positivity was solely significantly associated with younger age (P = .015). The associations were however insignificant in multivariate analysis. PD-L1 expression was significantly correlated with Ki-67 (P < .001) and TP53 (P = .02) expressions. PD-L2 expression was not correlated with either Ki-67 or TP53 expression. When grouped as combined expression (both negative vs. either positive), PD-L1/PD-L2 expression was associated with earlier recurrence (P < .001), and was negatively correlated with expression of Ki-67 (P < .001) but not with the expression of TP53. Conclusion: PD-L1/PD-L2 is positively expressed in chondrosarcoma and is associated with advanced clinical phenotype. PD-L1/PD-L2 expression is also associated with Ki-67 expression. Our results support the application of immune checkpoint blockade in chondrosarcoma.