ALBERT

Description: Abstract Dynamic changes in soil organic carbon (SOC) have become a popular topic in global research on organic carbon as part of the increasing attention being paid to food security and reducing greenhouse gas emissions. In this paper, the semiarid regions of China were selected as a research focus, and SOC data from 1980–2015 were analyzed using IBM SPSS Statistics 20.0 software. SOC in farmland varied according to cultivated land type, mulching material type, and planting method in the studied regions. The SOC content is 10.3–10.8 g/kg in supplementally irrigated land and flat dry land, 7.1–8.7 g/kg in terraced dry land and river beach land, and 6.2–6.4 g/kg in sloping dry land. The SOC content increased to 16.1–17.4 g/kg when crop stalks were used as mulch. The increase was only 11.5‐13.5 g/kg in soils mulched with film or sandstone. The SOC value in wheat, maize, and potatoes sown on single or double ridges was 2.4–3.2%, 35.7–36.4% and 4.4–4.8%, respectively, which are higher than the values for wheat, maize, and potatoes sown using the flat planting method. The SOC sequestering potential also varied according to the previously noted factors and was improved from 224.1–383.8% depending on cultivated land type, from 96.5–182.3% depending on mulching material type, and from 96.1–191.3% depending on planting method. The SOC sequestering potential can be improved by 453.2–757.4% with the integration of the optimal cultivated land type, mulching material type, and planting method. Thus, there is substantial soil carbon sequestration potential in China's semiarid regions. This article is protected by copyright. All rights reserved.

Description: Abstract Although the impact of El Niño–Southern Oscillation on the Tibetan Plateau (TP) is reflected through stable isotopes of precipitation and ice cores, the hydroclimate response of TP lakes to El Niño–Southern Oscillation is seldom investigated. Here we show that significant lake water deficit occurred on the central TP (CTP) due to a dramatic decrease in precipitation 2016 El Ni/2016 El Niño event, followed by extreme lake water surplus in 2016 and 2017 over most of the TP (except the eastern CTP). Similar but weaker lake shrinkage and afterward expansion can also be found during historical El Niño events. Further exploration reveals that the CTP dry anomaly during El Niño events tends to bridge the dry anomalies over India and northern China, thereby forming a dry zone along the northwestern edge of the Asian monsoon domain. This study may shed light on the prediction of lake level changes on the TP.

Description: ABSTRACT Numerical simulation in coupled elastic and poroelastic media is important in oil and gas exploration. However, the interface between elastic and poroelastic media is a challenge to handle. In order to deal with the coupled model, the first‐order velocity–stress wave equations are used to unify the elastic and poroelastic wave equations. In addition, an arbitrary high‐order discontinuous Galerkin method is used to simulate the wave propagation in coupled elastic–poroelastic media, which achieves same order accuracy in time and space domain simultaneously. The interfaces between the two media are explicitly tackled by the Godunov numerical flux. The proposed forms of numerical flux can be used efficiently and conveniently to simulate the wave propagation at the interfaces of the coupled model and handle the absorbing boundary conditions properly. Numerical results on coupled elastic–poroelastic media with straight and curved interfaces are compared with those from a software that is based on finite element method and the interfaces are handled by boundary conditions, demonstrating the feasibility of the proposed scheme in dealing with coupled elastic–poroelastic media. In addition, the proposed method is used to simulate a more complex coupled model. The numerical results show that the proposed method is feasible to simulate the wave propagation in such a media and is easy to implement.

Description: Angiotensin II (Ang II), a biologically active peptide of the renin–angiotensin system (RAS), plays an important role in promoting cell migration via Angiotensin II type 1 receptor (AT1R). In this study, we examined the mechanisms by which Ang II affected cell migration in AT1R-positive MDA-MB-231 human breast cancer cells. Ang II increased cell migration and expression of matrix metalloproteinase (MMP)-2,-9 in a dose-dependent manner. Ang II-mediated cell migration was reduced by specific blocking of MMP-2 and MMP-9, as well as with pretreatment with inhibitors of AT1R, phosphatidylinositol 3-kinase (PI3K), Akt, and NF-κB. Similarly, Ang II-mediated expression of MMP-2,-9 was downregulated by pretreatment with inhibitors of AT1R and PI3K. In addition, Ang II treatment significantly induced phosphorylation of PI3K, Akt, and resulted in increased NF-κB activity. These findings suggest that Ang II activates the AT1R/PI3K/Akt pathway, which further activates IKKα/β and NF-κB, resulting in enhanced expression of MMP-2,-9 and migration in human breast cancer cells. Therefore, targeting Ang II/AT1R/PI3K/Akt/NF-κB signaling could be a novel anti-metastatic therapy for breast cancer. J. Cell. Physiol. © 2014 Wiley Periodicals, Inc.

Description: With the development of high-performance aircraft, precise air data are necessary to complete challenging tasks such as flight maneuvering with large angles of attack and high speed. As a result, the flush air data sensing system (FADS) was developed to satisfy the stricter control demands. In this paper, comparative stuides on the solving model and algorithm for FADS are conducted. First, the basic principles of FADS are given to elucidate the nonlinear relations between the inputs and the outputs. Then, several different solving models and algorithms of FADS are provided to compute the air data, including the angle of attck, sideslip angle, dynamic pressure and static pressure. Afterwards, the evaluation criteria of the resulting models and algorithms are discussed to satisfy the real design demands. Futhermore, a simulation using these algorithms is performed to identify the properites of the distinct models and algorithms such as the measuring precision and real-time features. The advantages of these models and algorithms corresponding to the different flight conditions are also analyzed, furthermore, some suggestions on their engineering applications are proposed to help future research.

Description: Questions Above-ground, below-ground and individual mass–density relationships for perennial herbs were examined along a natural precipitation gradient in northern Tibet. We asked: (1) how do the self-thinning exponents respond to variation in precipitation; and (2) what mechanisms drive the observed population self-thinning? Location The alpine grassland of northern Tibet. Methods Forty-seven fenced sites along a precipitation gradient were established and surveyed in 2011 and 2012. Data (geographic coordinates, elevation, and vegetation information) were collected for Stipa purpurea populations at each site. Population self-thinning exponents were estimated using reduced major axis regression. Results The self-thinning exponents for below-ground (−1.27, −0.47) and individual biomass (−1.26, −0.46) increased with increasing mean annual precipitation, but those for above-ground biomass decreased with precipitation (0.18, −0.25). Soil resources (moisture and nutrients) are a more important constraining factor for below-ground components than light is for above-ground components. Root competition for below-ground resources dominated in S .  purpurea population self-thinning. The driving force of density regulation changed from above-ground competition to below-ground competition with increased drought stress. Our results indicate that an increased root/shoot ratio was linked to enhanced below-ground competition and weakened above-ground competition. Our study further confirmed the hypothesis that plant populations in different environments exhibit different biomass allocation patterns, which, in turn, leads to different biomass–density relationships. Conclusions Our study revealed the mechanisms of population self-thinning for perennial herbs in the extreme environment of northern Tibet, where below-ground processes play a critical role in regulating population self-thinning. Our study also advances understanding of the interactions between above- and below-ground processes, providing baseline knowledge useful for local grassland management. Above–ground, below–ground and individual mass–density relationships for Stipa purpurea populations were examined along a natural precipitation gradient in Northern Tibet. Our study revealed the mechanisms of population self–thinning for perennial herbs in the extreme environment of Northern Tibet, where below–ground process plays a critical role in regulating population self–thinning.

Description: A comprehensive method for the precise determination of Re, Os, Ir, Ru, Pt and Pd concentrations, as well as Os isotopic compositions in geological samples is presented. Samples were digested by the Carius tube method and the Os was extracted by conventional CCl 4 method. The Re, Ir, Ru, Pt and Pd were first subgroup separated from the matrix elements into Re-Ru, Ir-Pt and Pd by a 2 ml anion exchange column. Subsequently, the Re-Ru was further purified by a secondary 0.25 ml anion exchange column, or by microdistillation of Ru using CrO 3 -H 2 SO 4 as an oxidant followed by a secondary 0.25 ml anion exchange separation of Re. The Pd and Ir-Pt were further successively purified by an Eichrom-LN column to completely remove Zr and Hf, respectively. Rhenium, Ir, Ru, Pt and Pd were individually measured by multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS), except for Ru after micro-distillation purification was analysed by negative thermal ionisation mass spectrometry (N-TIMS). The analytical results for peridotite reference material WPR-1 agree well with the previously published data. Finally, several mafic rock reference materials including TDB-1, WGB-1, BHVO-2, BCR-2, BIR-1a and DNC-1a were analysed for Re-Os isotopes and platinum-group element concentrations to test their suitability for certification. This article is protected by copyright. All rights reserved.

Description: ABSTRACT As one of the most sensitive regions to climate change, the Qinghai-Xizang Plateau has been widely investigated as one unity for impacts of climate change on alpine grassland. However, previous findings might be confounded by distinct climate sensitivities at different elevations and different regional climates between Qinghai Province and Xizang Province, which lie at the two sides of Tanggula Mountains. In this study, we explored change trends of grassland vegetation, temperature and precipitation in growing season from 1982 to 2011, and elevation-dependent effects of climate change on grassland vegetation in the two provinces separately. The plateau grassland greenness gained improvement under climate warming and wetting during the past 30 years, especially in Qinghai Province. Temperature increased significantly with a warming magnitude of more than 1.5 °C over the plateau grassland. The interannual change of precipitation showed contrary trends between the two provinces. The main climate factor driving the grassland vegetation variation varied between the two provinces, with temperature being the main factor in Qinghai Province and precipitation being the main factor in Xizang Province. In particular, a more significant correlation between climate change and grassland vegetation variation was found at higher elevations, which reveals higher climate sensitivity in higher elevation areas of the plateau.

Description: Abstract Nitrous oxide (N2O) emissions from soil contribute to global warming and are in turn substantially affected by climate change. However, climate change impacts on N2O production across terrestrial ecosystems remain poorly understood. Here, we synthesised 46 published studies of N2O fluxes and relevant soil functional genes (SFGs, i.e. archaeal amoA, bacterial amoA, nosZ, narG, nirK and nirS) to assess their responses to increased temperature, increased or decreased precipitation amounts, and prolonged drought (no change in total precipitation but increase in precipitation intervals) in terrestrial ecosystem (i.e. grasslands, forests, shrublands, tundra and croplands). Across the dataset, temperature increased N2O emissions by 33%. However, the effects were highly variable across biomes, with strongest temperature responses in shrublands, variable responses in forests and negative responses in tundra. The warming methods employed also influenced the effects of temperature on N2O emissions (most effectively induced by open‐top chambers). Whole‐day or whole‐year warming treatment significantly enhanced N2O emissions, but day‐time, night‐time or short‐season warming did not have significant effects. Regardless of biome, treatment method and season, increased precipitation promoted N2O emission by an average of 55%, while decreased precipitation suppressed N2O emission by 31%, predominantly driven by changes in soil moisture. The effect size of precipitation changes on nirS and nosZ showed a U‐shape relationship with soil moisture; further insight into biotic mechanisms underlying N2O emission response to climate change remain limited by data availability, underlying a need for studies that report SFG. Our findings indicate that climate change substantially affects N2O emission and highlight the urgent need to incorporate this strong feedback into most climate models for convincing projection of future climate change.

Description: Abstract Since the 1980‐90s, international research efforts have augmented our knowledge of the physical and chemical properties of the Arctic Ocean water masses and recent studies have documented changes. Understanding the processes responsible for these changes is necessary to be able to forecast the local and global consequences of these property evolutions on climate. The present work investigates the distributions of geochemical tracers of particle fluxes and circulation in the Amerasian Basin and their temporal evolution over the last three decades (from stations visited between 1983 and 2015). Profiles of 230‐thorium (230Th) and 231‐protactinium (231Pa) concentration and neodymium isotopes (expressed as εNd) measured in the Amerasian Basin prior to 2000 are compared to a new, post‐2000s dataset. The comparison shows a large scale decrease in dissolved 230Th and 231Pa concentrations, suggesting intensification of scavenging by particle flux, especially in coastal areas. Higher productivity and sediment resuspension from the shelves appear responsible for the concentration decrease along the margins. In the basin interior, increased lateral exchanges with the boundary circulation also contribute to the decrease in concentration. This study illustrates how dissolved 230Th and 231Pa, with εNd support, can provide unique insights not only into changes in particle flux but also into the evolution of ocean circulation and mixing.