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Background: Large uncertainty in modeling land carbon (C) uptake heavily impedes the accurate prediction of the global C budget. Identifying the uncertainty sources among models is crucial for model improvement yet has been difficult due to multiple feedbacks within Earth System Models (ESMs). Here we present a Matrix-based Ensemble Model Inter-comparison Platform (MEMIP) under a unified model traceability framework to evaluate multiple soil organic carbon (SOC) models. Using the MEMIP, we analyzed how the vertically resolved soil biogeochemistry structure influences SOC prediction in two soil organic matter (SOM) models. By comparing the model outputs from the C-only and CN modes, the SOC differences contributed by individual processes and N feedback between vegetation and soil were explicitly disentangled. Results: Results showed that the multi-layer models with a vertically resolved structure predicted significantly higher SOC than the single layer models over the historical simulation (1900–2000). The SOC difference between the multi-layer models was remarkably higher than between the single-layer models. Traceability analysis indicated that over 80% of the SOC increase in the multi-layer models was contributed by the incorporation of depth-related processes, while SOC differences were similarly contributed by the processes and N feedback between models with the same soil depth representation. Conclusions: The output suggested that feedback is a non-negligible contributor to the inter-model difference of SOC prediction, especially between models with similar process representation. Further analysis with TRENDY v7 and more extensive MEMIP outputs illustrated the potential important role of multi-layer structure to enlarge the current ensemble spread and the necessity of more detail model decomposition to fully disentangle inter-model differences. We stressed the importance of analyzing ensemble outputs from the fundamental model structures, and holding a holistic view in understanding the ensemble uncertainty. [ABSTRACT FROM AUTHOR]

A systematic procedure for the determination of purity values of amino acid reference materials was developed by use of mass balance method where four categories of impurities (related structure impurities (RSIs), water, organic solvent residue (OSR), and non-volatile residue (NVR)) were quantified separately. The amount of RSIs was determined using a combination of three quantification methods. To ensure metrological traceability in the determination of RSIs, at least one such impurity in each candidate amino acid reference material was quantified using liquid chromatography–isotope dilution tandem mass spectrometry (LC-IDMS/MS). Other RSIs were determined using external calibration liquid chromatography–tandem mass spectrometry (LC-MS/MS) or o-phthaldialdehyde (OPA) derivatization, followed by liquid chromatography–ultraviolet (LC-UV) measurement. As the UV absorption of most RSIs came basically from the same chromophore after OPA derivatization, a relative peak area approach was used in the LC-UV method to quantify the amount of RSIs by comparing their peak areas with that of a reference RSI. The reference RSI was pre-selected and the amount determined by LC-IDMS/MS separately. The absence of D-amino acids was confirmed using Marfey's reagent derivatization, followed by LC-UV analysis. The amounts of water, OSR, and NVR were measured using Karl Fischer coulometry, gas chromatography–mass spectrometry (GC-MS) and thermogravimetry, respectively. By using this procedure, four amino acid (L-valine, L-leucine, L-isoleucine, and L-phenylalanine) certified reference materials (CRMs) were developed from the candidate materials. The homogeneity and stability of the CRMs were demonstrated by use of LC-IDMS/MS or OPA-LC-UV method, following the principles in ISO 17034 and ISO Guide 35. Graphical abstract [ABSTRACT FROM AUTHOR]

Background: Ischemic stroke is a serious cardiovascular disease with high morbidity and mortality rates that affects millions of people worldwide.Currently, the only therapy with proven efficacy for acute ischemic stroke is alteplase, however, it still has many shortcomings and limitations. Therefore,we screen new compounds from traditional Chinese medicine to explore their efficacy against ischemic reperfusion injury. Procyanidins, a natural productextracted from grapes seed, which have been shown can ameliorate cerebral ischemic injury. However, the underlying mechanism is still not very clear. Theaim of this study was to investigate the effect of procyanidins on middle cerebral artery occlusion/reperfusion (MCAO/R)-mediated cerebral ischemic injuryand its underlying possible mechanisms. Methods: SD rats were used to evaluate the effect of procyanidins on MCAO/R induced cerebral ischemic injury in vivo. Histological analysis was used toassess neuronal apoptosis. Cell signaling was assayed by Western blot. Results: In this study, we found that procyanidins can significantly ameliorate the middle cerebral artery occlusion/reperfusion (MCAO/R)-mediatedneurological deficits, and relieved brain edema, cerebral infarction volume, histopathological damage and apoptosis in rats. In addition, procyanidins canalso markedly inhibit MCAO/R and oxygen-glucose deprivation/reoxygenation (OGD/R)-mediated activation of TLR4-p38-NF-κB-NLRP3 signalingpathway in vitro and in vivo. Moreover, procyanidins can inhibit MCAO/R and OGD/R-induced the production of inflammatory cytokines such asinterleukin-1β (IL-1β) in vitro and in vivo. Besides, treatment with TLR4 inhibitor (Cli-095) in BV2 cell also shows the same effect. Conclusion: Altogether, these data suggested that procyanidins exerted a potential neuroprotective effect may by inhibit the TLR4-p38-NF-κB-NLRP3signaling pathway in the brain in MCAO/R rats. [ABSTRACT FROM AUTHOR]

Testosterone in human serum is commonly tested in clinical laboratories using immunoassay methods as well as liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods. To standardize and ensure the accuracy of the measurement results, reference procedures with higher metrological order are required. A simple measurement procedure based on one-step liquid-liquid extraction (LLE) and liquid chromatography-isotope dilution tandem mass spectrometry (LC-IDMS/MS) was developed for total testosterone in human serum. The procedure involved serum spiked with 13C3-testosterone, equilibration for 2 h, and extraction with an organic solvent. Testosterone certified reference material (CRM) was used as the calibration standard to ensure the traceability to the International System of Units (SI). Testosterone in serum CRMs from the National Institute for Standards and Technology (NIST) and LGC were used to validate the accuracy of the newly developed method. The deviations of the obtained values from the NIST and LGC certified values ranged from −0.55% to 0.45%. Similarly, the coefficient of variations (CVs) of the replicate measurements were in the range of 0.55% and 0.78%, respectively. The relative expanded uncertainties were comparable with those of the certified materials. The newly developed LC-IDMS/MS procedure demonstrated adequate trueness and precision, and was simple to perform. The method can be used for value assignment of testosterone in external quality assessment (EQA) materials as well as certification of CRMs in the future. [ABSTRACT FROM AUTHOR]

The Cu(I)-catalyzed alkyne-azide cycloaddition (CuAAC) has been developed into a powerful polymerization reaction for the synthesis of new polytriazoles with versatile properties. However, research on recyclable and reusable copper catalyst for click polymerization to meet the requirement of green chemistry was rarely reported. Copper nanoparticles were reported to be capable catalysts for CuAAC. Replacing conventional copper catalyst with copper nanoparticles may realize the recycle and reuse of the copper catalyst in click polymerization. In this paper, copper nanoparticles were prepared and used as an effective catalyst for click polymerization, and soluble polytriazoles with high molecular weights were obtained in excellent yields under optimized reaction conditions. Importantly, the copper nanoparticles can be recycled and reused for up to 11 times for the click polymerization. Moreover, introducing aggregation-induced emission (AIE)-active moiety of tetraphenylethylene into the monomers makes the resultant polymers retain the AIE feature. This work not only provides an efficient recyclable catalytic system for the azide-alkyne click polymerization, but also might inspire polymer chemists to use recyclable copper species to catalyze other polymerizations. [ABSTRACT FROM AUTHOR]

This paper aims to reveal the responses of global natural vegetation to future climate change in the twenty-first century. Thus, the dynamics of terrestrial net primary productivity (NPP) in three time slices, namely, 2030s, 2050s and 2070s are projected using a segmentation model that utilized 25 global climate models under the Representative Concentration Pathway 2.6 (RCP2.6) scenario. The results showed that forests would expand at the expense of grasslands and deserts in the current century. Terrestrial NPP is projected to increase globally from 127.04 ± 1.74 Pg DW·a in 2030s to 127.62 ± 2.57 Pg DW·a in 2070s. Temperate forest, the largest distributed vegetation, would contribute the most to the overall increase (548.50 Tg DW·a). The NPP of warm desert, savanna, and tropical forest is projected to increase by 31.03, 248.45 and 111.25 Tg DW·a, respectively. By contrast, the NPP of all the other vegetations would decline at the end of this century. In the tropical and the south temperate zones, terrestrial NPP is projected to decrease by 99.32 and 25.56 Tg DW·a, respectively, with the difference lying in the increasing-decreasing trend in the former and the continually decreasing trend in the latter. However, terrestrial NPP in the north temperate and north frigid zones is projected to increase consistently by 639.43 and 57.73 Tg DW·a, respectively. The 'increase-peak-decline' trend of greenhouses gases described in the RCP2.6 would lead to the warming and cooling periods during this century. The vegetation NPP of various ecosystems or climate zones would respond differently to the future climate change. In general, ecosystems in northern high latitudes would become more vulnerable to future climate change compared to other vegetations. [ABSTRACT FROM AUTHOR]

Grassland degradation received considerable concern because of its adverse impact on agronomic productivity and its capacity to provide goods and service. Climate change and human activities are commonly recognized as the two broad underlying drivers that lead to grassland degradation. In this study, a comprehensive method based on net primary productivity (NPP) was introduced to assess quantitatively the relative roles of climate change and human perturbations on worldwide grassland degradation from 2000 to 2010. The results revealed that at a global scale, 49.25 % of grassland ecosystems experienced degradation. Nearly 5 % of these grasslands experienced strong to extreme significant degradation. Climate change was the dominant cause that resulted in 45.51 % of degradation compared with 32.53 % caused by human activities. On the contrary, 39.40 % of grassland restoration was induced by human interferences, and 30.6 % was driven by climate change. The largest area of degradation and restoration both occurred in Asia. NPP losses ranged between 1.40 Tg C year (in North America) and 13.61 Tg C year (in Oceania) because of grassland degradation. Maximum NPP increase caused by restoration was 17.57 Tg C year (in North America). Minimum NPP was estimated at 1.59 Tg C year (in Europe). The roles of climate change and human activities on degradation and restoration were not consistent at continental level. Grassland ecosystems in the southern hemisphere were more vulnerable and sensitive to climate change. Therefore, climate change issues should be gradually integrated into future policies and plans for domestic grassland management and administration. [ABSTRACT FROM AUTHOR]

GIMMS (Global Inventory Modeling and Mapping Studies) NDVI (Normalised Difference Vegetation Index) from 1982 to 2006 and MODIS (Moderate Resolution Imaging Spectroradiometer) NDVI from 2001 to 2010 were blended to extract the grass coverage and analyze its spatial pattern. The response of grass coverage to climatic variations at annual and monthly time scales was analyzed. Grass coverage distribution had increased from northwest to southeast across China. During 1982-2010, the mean nationwide grass coverage was 34% but exhibited apparent spatial heterogeneity, being the highest (61.4%) in slope grasslands and the lowest (17.1%) in desert grasslands. There was a slight increase of the grass coverage with a rate of 0.17% per year. Increase in slope grasslands coverage was as high as 0.27% per year, while in the plain grasslands and meadows the grass coverage increase was the lowest (being 0.11% per year and 0.1% per year, respectively). Across China, the grass coverage with extremely significant increase (P<0.01) and significant increase (P<0.05) accounted for 46.03% and 11% of the total grassland area, respectively, while those with extremely significant and significant decrease accounted for only 4.1% and 3.24%, respectively. At the annual time scale, there are no significant correlations between grass coverage and annual mean temperature and precipitation. However, the grass coverage was somewhat affected by temperature in alpine and sub-alpine grassland, alpine and sub-alpine meadow, slope grassland and meadow, while grass coverage in desert grassland and plain grassland was more affected by precipitation. At the monthly time-scale, there are significant correlations between grass coverage with both temperature and precipitation, indicating that the grass coverage is more affected by seasonal fluctuations of hydrothermal conditions. Additionally, there is one-month time lag-effect between grass coverage and climate factors for each grassland types. [ABSTRACT FROM AUTHOR]

Purpose: To delineate the pterygoid canal (PC) configuration and its position in relation to surrounding important anatomical landmarks using three-dimensional reconstructive technology based on CT for the Chinese. Methods: The computerized tomography arteriography (CTA) data of 137 patients were retrospectively evaluated using neuroimaging three-dimensional reconstructive software. The morphological parameters of the PC as well as the spatial relationship and distance between the PC relative to internal carotid artery (ICA) and the foramen rotundum were evaluated. Results: 83.9 % of the PC can be identified by our neuroimaging three-dimensional reconstructive software. The mean distance from the PC to the ICA was 2.6 ± 1.2 mm. The mean distance between medial aspects of bilateral ICA was 19.6 ± 2.7 mm. The distal vertical and horizontal distances between the PC and foramen rotundum were 5.2 ± 3.2 and 6.1 ± 2.8 mm, respectively. All the proximal end of the PC were inferior-lateral to the ICA. The PC mainly (92.9 %) ran posteriorly with a medial to lateral direction. The distance from the PC to ICA was positively correlated with the distance between bilateral ICA and the distal diameter of the PC. The vertical distance between the PC and foramen rotundum was positively correlated with the length of the PC and the horizontal distance between the PC and foramen rotundum. Conclusions: Understanding the configuration and spatial relationship of the PC may be helpful to improve the accuracy and safety of operation during the expanded transnasal endoscopic approaches to skull base. The three-dimensional reconstructive virtual anatomic technology may be a useful tool to delineate the PC configuration and its position to surrounding important anatomical landmarks. [ABSTRACT FROM AUTHOR]

Hemoglobin (Hb) released from extravasated erythrocytes may have a critical role in the process of blood-brain barrier (BBB) disruption and subsequent edema formation after intracerebral hemorrhage (ICH). Excessive nitric oxide (NO) production synthesized by nitric oxide synthase (NOS) has been well documented to contribute to BBB disruption. However, considerably less attention has been focused on the role of NO in Hb-induced BBB disruption. This study was designed to examine the hypothesis that Hb-induced NOS overexpression and excessive NO production may contribute to the changes of tight junction (TJ) proteins and subsequent BBB dysfunction. Hemoglobin was infused with stereotactic guidance into the right caudate nucleus of male Sprague Dawley rats. Then, we investigated the effect of Hb on the BBB permeability, changes of TJ proteins (claudin-5, occludin, zonula occludens-1 (ZO-1), and junctional adhesion molecule-1 (JAM-1)), iron deposition, expression of inducible NOS (iNOS) and endothelial NOS (eNOS), as well as NO production. Hb injection caused a significant increase in BBB permeability. Significant reduction of claudin-5, ZO-1, and JAM-1 was observed after Hb injection as evidenced by PCR and immunofluorescence. After a decrease at early stage, occludin showed a fivefold increase in mRNA level at 7 days. Significant iron deposition was detectable from 48 h to 7 days in a time-dependent manner. The iNOS and eNOS levels dramatically increased after Hb injection concomitantly with large quantities of NO released. Furthermore, enhanced iNOS or eNOS immunoreactivity was co-localized with diffused or diminished claudin-5 staining. We concluded that overexpressed NOS and excessive NO production induced by Hb may contribute to BBB disruption, which may provide an important potential therapeutic target in the treatment of ICH. [ABSTRACT FROM AUTHOR]

The vegetation coverage dynamics and its relationship with climate factors on different spatial and temporal scales in Inner Mongolia during 2001-2010 were analyzed based on MODIS-NDVI data and climate data. The results indicated that vegetation coverage in Inner Mongolia showed obvious longitudinal zonality, increasing from west to east across the region with a change rate of 0.2/10°N. During 2001-2010, the mean vegetation coverage was 0.57, 0.4 and 0.16 in forest, grassland and desert biome, respectively, exhibiting evident spatial heterogeneities. Totally, vegetation coverage had a slight increasing trend during the study period. Across Inner Mongolia, the area of which the vegetation coverage showed extremely significant and significant increase accounted for 11.25% and 29.13% of the area of whole region, respectively, while the area of which the vegetation coverage showed extremely significant and significant decrease accounted for 7.65% and 26.61%, respectively. On inter-annual time scale, precipitation was the dominant driving force of vegetation coverage for the whole region. On inter-monthly scale, the change of vegetation coverage was consistent with both the change of temperature and precipitation, implying that the vegetation growth within a year is more sensitive to the combined effects of water and heat rather than either single climate factor. The vegetation coverage in forest biome was mainly driven by temperature on both inter-annual and inter-monthly scales, while that in desert biome was mainly influenced by precipitation on both the two temporal scales. In grassland biome, the yearly vegetation coverage had a better correlation with precipitation, while the monthly vegetation coverage was influenced by both temperature and precipitation. In grassland biome, the impacts of precipitation on monthly vegetation coverage showed time-delay effects. [ABSTRACT FROM AUTHOR]