•SOC and TSN contents are mainly concentrated in the surface layer among land types.•Soil erosion, land-use change and landscape position have great effects on SOC and TSN stocks at a landscape ...scale.•Artificial forestland is an optimal choice to increase C and N sequestration.
Erosion influences the vertical and horizontal distribution patterns of soil and soil organic carbon (SOC) at a landscape scale. To further understand the effect of erosion on SOC and total soil nitrogen (TSN) stocks in relation to land use types after the implementation of the “Grain for Green” program in the Loess hill-gully region, the SOC, TSN, and Caesium-137 (137Cs) contents were analyzed at three selected landscape positions under three land-use types: artificial grassland (AGL), native grassland (NGL) and artificial plantation of Robinia pseudoacacia (AFL). The results showed that all land uses experienced considerable net erosion since the mid-1950s, with an average total loss depth of 2.05cm for AFL, 1.49cm for AGL, and 0.54cm for NGL. The SOC stocks in AFL and NGL were 72.3% and 26.2% lower, respectively, than that in AGL in the 0–100cm soil layer, and significant positive correlation between SOC and TSN stocks on each layer in the soil profile was observed (R2>0.90). The result showed that compared with other land-use types, AGL had a greater SOC and TSN sequestration capacity. The contents of SOC and TSN were positively correlated with the amount of 137Cs in AFL and NGL (R2=0.97, 0.97 for AFL, respectively, and R2=0.90, 0.90 for NGL, respectively; n=3), whereas no significant correlation was found in AGL (R2=0.41, 0.01, respectively; n=3). The results indicated that AGL was an optimal choice to mitigate soil carbon and nitrogen loss and to increase C and N sequestration in the Loess hilly–gully region. A complex process should be considered for the distribution patterns of SOC and TSN after afforestation since 1999.
The coupling of soil erosion (especially interrill erosion by water) and the dynamics of soil organic carbon (SOC) in agricultural landscapes has been widely studied over the past two decades. To ...date, however, the role of soil erosion in global C cycle remains a topic of debate. Numerous questions remain to be addressed before determining the C sink/source effect of soil erosion, especially for the mineralization and sequestration of eroded SOC upon erosion, transport and deposition. In this review, we provide a comprehensive cross-disciplinary review on SOC mineralization and sequestration at sites of erosion, along the transport pathway and at depositional sites. The current state of knowledge on the impacts of erosion-induced soil aggregate breakdown and formation, removal of SOC from eroding sites and deep burial of SOC at depositional sites on the mineralization and sequestration of SOC are presented. Furthermore, we provide an overview of the conceptual relations between soil biological properties (microbial abundance, species diversity, community composition and enzyme activity) and the mineralization and sequestration of SOC in eroded agricultural landscapes, which are often overlooked by previous research and reviews. The comprehensive understanding of physical, chemical and biological mechanisms affecting the mineralization and sequestration of eroded SOC provides important insights to balance the global carbon budget and finally holds the answer on the carbon sink/source controversy.
•Dynamic replacement of OC at eroding site induces a positive priming effect•Erosion-induced decline in fungal:bacterial ratio increases SOC turnover rate•The breakdown of soil aggregates during transport accelerates SOC mineralization•Deep burial of eroded SOC prolongs its mean residence time in soil•High enzyme activities at depositional sites negatively impact SOC sequestration
Deregulation or mutation of the
gene causes various tumors, including clear cell renal cell carcinoma (ccRCC). Although several splice variants of EZH2 have been identified, little is known about how ...EZH2 splicing is regulated or the contribution of alternative splicing to its protumorigenic functions.
We conducted RT-PCR, Western blot analysis, and IHC techniques to examine EZH2 and its alternative splicing transcript expression in renal cancer tissue and renal cancer cell lines. Proliferation, migration, clonogenicity, and tumorigenicity of renal cancer cells either exhibiting knockdown of EZH2 or its splicing factor SF3B3 were assessed by CCK8, Transwell assay, and murine xenograft experiments.
We found that the inclusion of alternative EZH2 exon 14 was significantly increased in ccRCC samples and renal cancer cell lines. In ccRCC lines, enforced expression of EZH2Δ14 inhibited, and EZH2 promoted, cell growth, migration, proliferation, and tumorigenicity in a xenograft model. Mechanistic studies demonstrated that EZH2Δ14 isoform functions as a dominant-negative inhibitor of full-length EZH2. Coexpression of EZH2Δ14 variant with full-length EZH2 not only abrogated DAB2IP and HOXA9 suppression but also inhibited EZH2-driven tumorigenesis. Strikingly, the splicing factor SF3B3 stimulates inclusion of exon14 and has pro-proliferative activity. Importantly, the upregulation of SF3B3 expression observed in clinical ccRCC samples parallels the increased inclusion of EZH2 exon14, and the SF3B3 level is associated with higher tumor stage and poor overall survival.
These results suggest SF3B3 as a key regulator of EZH2 pre-mRNA splicing and SF3B3 may represent a novel prognostic factor and potential therapeutic target in ccRCC.
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•We proposed a method for assessing trade-offs between ecological and urbanization.•Trade-off of land-use analysis aids understanding ecosystem services (ESs)•We assessed changes of ESs and confirmed ...their synergies and trade-offs.•Urbanization within reasonable range does not negatively affect ESs at basin scale.•ESs should be taken into account in policy making for developing regions.
The trade-offs between ecological construction and urbanization changes in land-use, which can affect ecosystem services. This study aimed to analyze the trade-offs between urbanization and ecological construction through land-use change, and then to explore its impact on ecosystem services. We developed a coefficient for analyzing LUCC caused by ecological construction and urbanization. The spatio-temporal patterns of three ecosystem services (Water yield, Net primary production, Soil conservation) in the Xiangjiang River Basin (XRB) of China were identified and the trade-offs and synergies between ecosystem services explored at different spatial scales. The average trade-off coefficients between ecological construction and urbanization of upstream, midstream, downstream, and the whole basin were 0.20, −0.27, −0.46 and −0.37 respectively show that the LUCC was dominated by urbanization in the XRB from 2000 to 2015. However, ecological construction improved ecosystem services. The growth rates in NPP, soil conservation, and water yield were 10.88%, 2.23%, and 19.82%, respectively, between 2000 and 2015. We also confirmed three ecosystem services were spatially dominated by synergies (0<R<0.3, p<0.01). Temporally, three ecosystem services went from negative synergy or trade-off to positive synergy. Consequently, our results indicate that the trade-off between within reasonable range ecological construction and urbanization does not mean ecosystem services inevitably decline at the whole basin scale. However, land-use planning and policy making for rapidly urbanizing regions should take ecosystem services into account to preserve natural ecosystems.
•Multiple tracers were employed to identify the sources of eroded OM in sediments.•Gully banks were the main contributing sources to eroded bulk OM at multiple scales.•Sediment bulk OM mainly sourced ...from the region with light erosion intensity.•Biological production of OM impacted on the dynamics of water-extractable OM.
Erosion is a fundamental phenomenon that governs the biogeochemical cycle of carbon (C) in the Earth system. Understanding the fate of eroded C at the watershed scale thus provides essential guidance for balancing the C budget and evaluating soil management strategies. In this study, we collected a total of 229 topsoils of source materials land use types (forests, grassland, cropland, orchard, and fallow) and gully bank and a total of 56 surface sediment samples main river channel (18) and three tributaries (38) with different erosion intensity. Multiple tracers (C and nitrogen (N) isotopes, molecular n-alkane biomarker, and spectroscopic indices) applied widely were then analyzed to determine relative source contributions to eroded organic matter (OM) (including bulk OM and water-extractable OM) in sediments at a broader watershed on the Loess Plateau of China. The results from an isotopic mixing model analysis showed that gully bank was the primary contributor of bulk OM in sediments, accounting for mean probability estimate (MPE) 55.3%, followed by “grassland” (MPE 21.0%), “cropland” (MPE 14.4%), and “forests” (MPE 9.3%). The contributions of grassland and cropland showed an increasing trend from upstream to downstream sections of the studied watershed. The contribution of forests was found higher in upstream than those of midstream and downstream. Along with previous evidences, our results show that erosion intensity mainly affects the proportion of C source, where gully bank was found as the highest contributor in three associated catchments, especially in region with light erosion intensity. We further demonstrated that the sediment bulk OM deposited was mainly derived from the region with light erosion intensity at the broader watershed scale. Moreover, results of n-alkane ratios and spectroscopic indices also implied that biological production of OM other than terrestrial sources (i.e., soil OM) might play a critical role in source contribution of water-extractable OM in sediments of main river channel.
High accumulation of hyaluronan (HA) in the tumor microenvironment leads to an increase in the interstitial pressure and reduction perfusion of drugs. Furthermore, high molecular-weight (HMW)-HA ...suppresses M1 macrophage polarization, enhances M2 polarization, and induces immunosuppression. Hyaluronidase treatment have attempted to decrease the quantity of HA in tumors. However, hyaluronidase-driven HA degradation driven accelerates tumor cell metastasis, which is a major cause of mortality in cancer patients. Thus, we designed a novel exosome-based drug delivery system (DDS), named Exos-PH20-FA, using genetic engineering to express human hyaluronidase (PH20) and self-assembly techniques to modify the exosomes with folic acid (FA). Our results show that Exos-PH20-FA degraded HMW-HA to low-molecular-weight (LMW)-HA. Moreover, LMW-HA polarized macrophages to the M1 phenotype and reduced the number of relevant immunosuppressive immunocytes which changed the immune microenvironment from an immunosuppressive to immunosupportive phenotype. Furthermore, we demonstrated Exos-PH20-FA directly reduced hyaluronidase-induced metastasis of tumor cells. This tumor treatment also allowed an enhanced delivery of chemotherapy by tumor-targeting effect with FA modification. Our findings indicate that Exos-PH20-FA improves tumor treatment efficiency and reduces the side effects of hyaluronidase treatment, namely tumor cell metastasis. This all-in-one exosome-based HA targeting DDS maybe a promising treatment that yields more efficient and safer results.
•High molecular-weight hyaluronan is related to tumor progression.•The degradation of hyaluronan enhance cancer cell migration and metastasis.•Folic acid can target tumor and inhibit tumor cell migration.•Exosomes are ideal carriers for chemotherapeutics, folic acid and hyaluronidase.
Soil erosion is a key variable in the biogeochemical cycle of carbon (C) on the Earth's surface. However, questions remain about the roles of land use and erosion intensity on the composition, ...source, and fate of soil C eroded from terrestrial to fluvial systems. In this study, chemical characteristics of eroded water-extractable organic matter (WEOM) in soils and sediments, as well as subsequent source identification, were inferred from UV–Visible absorption and fluorescence excitation emission matrix (EEM)-parallel factor analysis (PARAFAC) in study sites that include land uses and gully banks, experiencing three levels of erosion intensity in a semi-arid region of China. 13C and 15N isotopic signatures along with elemental ratios were also successfully employed to explore the source of bulk soil organic matter (SOM) in sediments. We found a much greater contribution of condensed aromatic structures and hydrophobic fraction of soluble organic compounds in forest soils compared to croplands at eroding sites, where these variables were greater than those of depositional sites. The results from fluorescence analysis in soil materials showed that erosion intensity has a negligible influence on WEOM quality. The EEM-PARAFAC with fluorescence indices indicated that biological production of soil substrates can also play a key role in the dynamics of WEOM induced by soil erosion. Our results from an isotopic mixing model analysis showed that gully bank soil was the primary sources of sedimentary SOM in all regions with different erosion intensities (mean probability estimate (MPE) 100% for the region with light erosion intensity, 36.18% for the region with high erosion intensity, and 99.25% for the region with extremely high erosion intensity). However, orchard and grassland were also the main contributors for the SOM in sediments in regions with high erosion intensity, accounting for MPE 29.93% and 33.89%, respectively. Our findings demonstrate that land use and erosion intensity have significant effect on nature of eroded OM.
•Spectroscopic indices and EEM-PARAFAC were used to characterize chemical composition of WEOM.•Greater presence of aromatics in soils at eroding sites than at depositional sites was found.•Biological activities play a key role in dynamics of soluble organic C induced by soil erosion.•The OM of sediments in higher erosion intensity regions originated mainly from cropland and orchard.
Continuous-wave (CW) lasers are widely used in laser polishing, but with CW laser polishing, it is difficult to reduce the surface roughness to 0.2 µm from an original value exceeding 1.0 µm. The aim ...of this study is to develop an innovative method of laser polishing assisted by a steady magnetic field to overcome that bottleneck and produce smoother surfaces. Two experiments confirm the hypothesis that the molten pool overflows during melting peaks to flow into valleys in CW laser polishing, resulting in secondary roughness that causes the aforementioned quality bottleneck. To either reduce or eliminate this secondary roughness, a steady magnetic field is used during CW laser polishing to suppress the overflow of the molten pool. A three-dimensional surface profiler, a scanning electron microscope, and a nanometer indentation tester are used to characterize and analyze the microstructure and properties of the materials. The experimental results show that the Lorentz force due to the steady magnetic field plays an important suppression role in reducing the secondary roughness.
The powder transport characteristics and flow field structure can significantly affect the quality of laser direct metal deposition (LDMD), which are in relation to nozzle structure and powder ...feeding parameters. Numerical simulation based on the gas-solid two-phase theory is the most effective way to study those. In this work, a double-ring coaxial nozzle was developed, and a 3D numerical model of this nozzle considering particle collision was established to obtain particle space trajectory and powder jet structure. Combining with experiments, the aerodynamics of the nozzle, the transport phenomenon, flow field, and deposition forming of powder particles in the LDMD were studied. Moreover, their internal relation was discussed. Results show that the developed nozzle could transport powder well and prepare excellent deposited layers. The numerical model can accurately predict the structure and transport characteristics of powder jet flow. The powder jet flow is easier to converge, and the focus moves up due to the collision. With the increase of powder feeding rate, the powder jet flow becomes divergent, and the focal points are separated so that the axial concentration distribution presents a “double-peak” characteristic, which is beneficial to reduce the laser attenuation rate on the transmission channel and to ensure the formation of the molten pool by the substrate. The appropriate size of the deposited layer can be obtained at the powder-carrying gas flow rate of 4 L/min and the powder feeding rate of 2.0–3.6 g/min, with the powder utilization ratio up to 54.2% and the microstructure being uniform and dense, meeting the requirement of industrial application.
Optical fiber Fabry–Perot sensors have long been the focus of researchers in sensing applications because of their unique advantages, including highly effective, simple light path, low cost, compact ...size, and easy fabrication. Microcantilever-based devices have been extensively explored in chemical and biological fields while the interrogation methods are still a challenge. The optical fiber probe microcantilever sensor is constructed with a microcantilever beam on an optical fiber, which opens the door for highly sensitive, as well as convenient readout. In this review, we summarize a wide variety of optical fiber probe microcantilever sensors based on Fabry–Perot interferometer. The operation principle of the optical fiber probe microcantilever sensor is introduced. The fabrication methods, materials, and sensing applications of an optical fiber probe microcantilever sensor with different structures are discussed in detail. The performances of different kinds of fiber probe microcantilever sensors are compared. We also prospect the possible development direction of optical fiber microcantilever sensors.
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