Kinetic Modulation of Carbon Nanotube Growth in Direct Spinning for High-Strength Carbon Nanotube Fibers.

With impressive individual properties, carbon nanotubes (CNTs) show great potential in constructing high-performance fibers. However, the tensile strength of as-prepared carbon nanotube fibers (CNTFs) by floating catalyst chemical vapor deposition (FCCVD) is plagued by the weak intertube interaction between the essential CNTs. Here, we developed a chlorine (Cl)/water (H2O)-assisted length furtherance FCCVD (CALF-FCCVD) method to modulate the intertube interaction of CNTs and enhance the mechanical strength of macroscopic fibers. The CNTs acquired by the CALF-FCCVD method show an improvement of 731% in length compared to that by the conventional iron-based FCCVD system. Moreover, CNTFs prepared by CALF-FCCVD spinning exhibit a high tensile strength of 5.27 ± 0.27 GPa (4.62 ± 0.24 N/tex) and reach up to 5.61 GPa (4.92 N/tex), which outperforms most previously reported results. Experimental measurements and density functional theory calculations show that Cl and H2O play a crucial role in the furtherance of CNT growth. Cl released from the decomposition of methylene dichloride greatly accelerates the growth of the CNTs; H2O can remove amorphous carbon on the floating catalysts to extend their lifetime, which further modulates the growth kinetics and improves the purity of the as-prepared fibers. Our design of the CALF-FCCVD platform offers a powerful way to tune CNT growth kinetics in direct spinning toward high-strength CNTFs.

Carbon Nanotube-Directed 7 GPa Heterocyclic Aramid Fiber and Its Application in Artificial Muscles.

Poly(p-phenylene-benzimidazole-terephthalamide) (PBIA) fibers with excellent mechanical properties are widely used in fields that require impact-resistant materials such as ballistic protection and aerospace. The introduction of heterocycles in polymer chains increases their flexibility and makes it easier to optimize the fiber structure. However, the inadequate orientation of polymer chains is one of the main reasons for the large difference between the measured and theoretical mechanical properties of PBIA fibers. Herein, carbon nanotubes (CNTs) are selected as an orientation seed. Their structural features allow CNTs to orient during the spinning process, which can induce an orderly arrangement of polymers and improve the orientation of the fiber microstructure. To ensure the complete 1D topology of long CNTs (≈10 µm), PBIA is used as an efficient dispersant to overcome dispersion challenges. The p-CNT/PBIA fibers (10 µm single-walled carbon nanotube 0.025 wt%) exhibit an increase of 22% in tensile strength and 23% in elongation, with a maximum tensile strength of 7.01 ± 0.31 GPa and a reinforcement efficiency of 893.6. The artificial muscle fabricated using CNT/PBIA fibers exhibits a 34.8% contraction and a 25% lifting of a 2 kg dumbbell, providing a promising paradigm for high-performance organic fibers as high-load smart actuators.

Response of grassland productivity to climate change and anthropogenic activities in arid regions of Central Asia.

BACKGROUND: Quantitative evaluations of the relative impacts of climate change and anthropogenic activity on grasslands are significant for understanding grassland degradation mechanisms and controlling degraded grasslands. However, our knowledge about the effects of anthropogenic activities and climate change on the grassland in a mountain basin system in arid regions of Central Asia is still subject to great uncertainties. METHODS: In this research, we have chosen the net primary productivity (NPP) as an index for revealing grassland dynamics processes. Moreover, the human appropriation of net primary production (NPPH), which was calculated as the potential NPP (NPPP) minus the actual NPP (NPPA), was applied to distinguish the relative influences of climate change and human activities on the grassland NPP variations in a mountain basin system of Central Asia from 2001-2015. RESULTS: The results indicated that the grassland NPPA showed an increasing trend (35.88%) that was smaller than the decreasing trend (64.12%). The respective contributions of human activity, climate change and the two together to the increase in the NPPA were 6.19%, 81.30% and 12.51%, respectively. Human activity was largely responsible for the decrease in the grassland NPPA, with the area experiencing human-induced decreases accounting for 98.21% of the total decreased area, which mainly occurred during spring/autumn pasture and winter pasture. Furthermore, the average grazing pressure index (GPI) values of summer pastures, spring/autumn pasture and winter pastures were 1.04, 3.03 and 1.83, respectively, from 2001-2015. In addition, negative correlations between the NPP and GPI occupied most of the research area (92.41%). DISCUSSION: Our results indicate that: (i) anthropogenic activities were the primary cause of the reduction in the grassland NPP, especially grazing activities. (ii) For areas where the grassland NPP has increased, precipitation was the dominant climatic factor over temperature in controlling the grassland NPP changes in the study area. (iii) The findings of the current research indicate that some measures should be taken to reduce livestock pressure, and artificial grasslands can be built along the Irtysh River and the Ulungur River to relieve grazing pressure on spring/autumn pastures and winter pastures. Our results could provide reliable information for grassland management and the prevention of grassland degradation in arid regions of Central Asia.

Flexible Zinc-Ion Hybrid Fiber Capacitors with Ultrahigh Energy Density and Long Cycling Life for Wearable Electronics.

Emerging wearable electronics require flexible energy storage devices with high volumetric energy and power densities. Fiber-shaped capacitors (FCs) offer high power densities and excellent flexibility but low energy densities. Zn-ion capacitors have high energy density and other advantages, such as low cost, nontoxicity, reversible Faradaic reaction, and broad operating voltage windows. However, Zn-ion capacitors have not been applied in wearable electronics due to the use of liquid electrolytes. Here, the first quasisolid-state Zn-ion hybrid FC (ZnFC) based on three rationally designed components is demonstrated. First, hydrothermally assembled high surface area and conductive reduced graphene oxide/carbon nanotube composite fibers serve as capacitor-type positive electrodes. Second, graphite fibers coated with a uniform Zn layer work as battery-type negative electrodes. Third, a new neutral ZnSO4 -filled polyacrylic acid hydrogel act as the quasisolid-state electrolyte, which offers high ionic conductivity and excellent stretchability. The assembled ZnFC delivers a high energy density of 48.5 mWh cm-3 at a power density of 179.9 mW cm-3 . Further, Zn dendrite formation that commonly happens under high current density is efficiently suppressed on the fiber electrode, leading to superior cycling stability. Multiple ZnFCs are integrated as flexible energy storage units to power wearable devices under different deformation conditions.

Role of SIRT2 in Regulation of Stemness of Cancer Stem-Like Cells in Renal Cell Carcinoma.

BACKGROUND/AIMS: Cancer stem cells (CSCs) contribute to tumorgenesis, invasion and metastasis, and are typically resistant to chemotherapy. Recent reports showed that SIRT2 was upregulated in several cancers. However, whether SIRT2 may be a CSC marker in renal cell carcinoma (RCC) is not clear. METHODS: The SIRT2 levels in both RCC samples and the corresponding normal kidney samples (NT) were assessed by RT-qPCR and ELISA. The association between SIRT2 levels and patient survival was examined using Bivariate correlation analysis by Spearman's Rank Correlation Coefficients. The survival of the patients was analyzed using Kaplan-Meier curve. In vitro, 2 RCC cell lines were co-transduced with a lentivirus expressing both a green fluorescent protein and a luciferase reporter under a cytomegalovirus promoter, and another lentivirus expressing a nuclear red fluorescent protein reporter under the control of a SIRT2 promoter for differentiating SIRT2+ vs SIRT2- RCC cells by flow cytometry. The SIRT2+ vs SIRT2- RCC cells were examined for the potential of forming tumor sphere in a tumor sphere formation assay, resistance to fluorouracil-induced apoptosis by CCK-8 assay, and the frequency of forming tumor in vivo after serial adoptive transplantation by bioluminescence. RESULTS: The levels of SIRT2 were higher in RCC samples than NT. The prognosis of RCC patients with high SIRT2 was worse than that of with low SIRT2. Compared to SIRT2- cells, SIRT2+ cells formed more tumor spheres, appeared to be more resistant towards fluorouracil-induced apoptosis, and generated bigger tumors with higher frequency after serial adoptive transplantation. CONCLUSION: SIRT2 may be highly expressed in the RCC stem-like cells and regulates cancer metastasis. Selective knockout of SIRT2 or elimination of SIRT2+ cells may improve the therapeutic outcome for patients with RCC.

Scenario analysis of ecosystem service changes and interactions in a mountain-oasis-desert system: a case study in Altay Prefecture, China.

Scenario analysis of ecosystem services (ES) can provide a scientific basis for ecosystem management. The objective of this study was to reveal the effects of future land use scenarios on ES in a mountain-oasis-desert system (MODS). We first simulated land use changes for the period of 2015-2035 in Altay Prefecture under three different scenarios: business as usual (BAU), economic development (ED), and ecological conservation (EC). We then evaluated water yield (WY), crop production (CP), soil conservation (SC), sand fixation (SF), carbon sequestration (CS), and aesthetic value (AV) and investigated the multiple interactions among ES at the regional and grid scales. The results showed that SC, CS, and AV continually increased, WY continually decreased under the three scenarios. Our study revealed that the multiple interactions among ES were spatially heterogeneous in the MODS and the spatial heterogeneities changed across scenarios. The locations of and causes for the formation of the multiple interactions among ES were identified based on spatial analysis. This information can help decision-makers develop targeted and differentiated ecosystem management strategies. This study can increase the understanding of the multiple interactions among ES. Our findings can provide a reference for studies of other regions with the MODS structure.

Effects of climate warming and prolonged snow cover on phenology of the early life history stages of four alpine herbs on the southeastern Tibetan Plateau.

PREMISE OF THE STUDY: Much research has focused on plant responses to ongoing climate change, but there is relatively little information about how climate change will affect the early plant life history stages. Understanding how global warming and changes in winter snow pattern will affect seed germination and seedling establishment is crucial for predicting future alpine population and vegetation dynamics. METHODS: In a 2-year study, we tested how warming and alteration in the snowmelt regime, both in isolation and combination, influence seedling emergence phenology, first-year growth, biomass allocation, and survival of four native alpine perennial herbs on the southeastern Tibetan Plateau. KEY RESULTS: Warming promoted seedling emergence phenology of all four species and biomass per plant of two species but reduced seedling survival of three species. Prolonged snow cover partly mediated the affects of warming on Primula alpicola (survival and biomass), Pedicularis fletcheri (phenology, biomass, and root:shoot ratio) and Meconopsis integrifolia (survival). For the narrowly distributed species M. racemosa, seedling growth was additively decreased by warming and prolonged snow cover. CONCLUSIONS: Both warming and alteration of the snow cover regime can influence plant recruitment by affecting seedling phenology, growth, and survival, and the effects are largely species-specific. Thus, climate change is likely to affect population dynamics and community structure of the alpine ecosystem. This is the first experimental demonstration of the phenological advancement of seedling emergence in the field by simulated climate warming.

Effects of grazing exclusion on the grassland ecosystems of mountain meadows and temperate typical steppe in a mountain-basin system in Central Asia's arid regions, China.

Grazing exclusion has been proposed as a method of restoring degraded grassland ecosystems. However, its effectiveness remains poorly understood in mountain-basin grasslands in arid regions. Thus, we investigated the plant community characteristics, C and N storage levels, and soil organic carbon and total nitrogen concentrations and storage within the upper 0-40 cm soil layer in a grazed grassland (GG) and a fenced grassland (FG) with grazing exclusion in mountain meadow (MM) and temperate typical steppe (TTS) habitats in a mountain-basin ecosystem in an arid region of Central China, which are both vital grassland resources for livestock grazing and ecological conservation. In MM, our investigation revealed that grazing exclusion was beneficial to the productivity, coverage, height, diversity, and C and N storage of aboveground plants. However, grazing exclusion was not an effective option for soil C and N sequestration. In TTS, grazing exclusion effectively improved the plant productivity, coverage, height, plant and soil C and N sequestration, although it was not beneficial for maintaining plant diversity. Our findings suggest that reduced or rotational grazing may be a better choice than grazing exclusion in MM. In addition, considering the trade-off between biomass productivity and species diversity in TTS, short-term grazing exclusion should be considered. Additionally, grazing exclusion should be combined with other appropriate measures rather than operating on a standalone basis.

Andrographolide sensitizes prostate cancer cells to TRAIL-induced apoptosis.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising agent for anticancer therapy. The identification of small molecules that can establish the sensitivity of prostate cancer (PCa) cells to TRAIL-induced apoptosis is crucial for the targeted treatment of PCa. PC3, DU145, JAC-1, TsuPr1, and LNCaP cells were treated with Andrographolide (Andro) and TRAIL, and the apoptosis was measured using the Annexin V/PI double staining method. Real time-polymerase chain reaction (PCR) and Western blot analysis were performed to measure the expression levels of target molecules. RNA interference technique was used to down-regulate the expression of the target protein. We established a nude mouse xenograft model of PCa, which was used to measure the caspase-3 activity in the tumor cells using flow cytometry. In this research study, our results demonstrated that Andro preferentially increased the sensitivity of PCa cells to TRAIL-induced apoptosis at subtoxic concentrations, and the regulation mechanism was related to the up-regulation of DR4. In addition, it also increased the p53 expression and led to the generation of reactive oxygen species (ROS) in the cells. Further research revealed that the DR4 inhibition, p53 expression, and ROS generation can significantly reduce the apoptosis induced by the combination of TRAIL and Andro in PCa cells. In conclusion, Andro increases the sensitivity of PCa cells to TRAIL-induced apoptosis through the generation of ROS and up-regulation of p53 and then promotes PCa cell apoptosis associated with the activation of DR4.

Effects of land use and climate change on ecosystem services in Central Asia's arid regions: A case study in Altay Prefecture, China.

The sustainable use of ecosystem services (ES) can contribute to enhancing human well-being. Understanding the effects of land use and climate change on ES can provide scientific and targeted guidance for the sustainable use of ES. The objective of this study was to reveal the way in which land use and climate change influence the spatial and temporal variations of ES in the mountain-oasis-desert system (MODS). In this study, we assessed water yield, soil conservation, crop production, and sand fixation in 1990, 2000, and 2010 in Altay Prefecture, which is representative of the MODS, based on widely used biophysical models. Moreover, we analyzed the effects of different land use and climate change conditions on ES. The results show that the area of forest and bare land decreased in Altay Prefecture. In contrast, the area of grassland with low coverage and cropland increased. The climate of this area presented an overall warming-wetting trend, with warming-drying and cooling-wetting phenomena in some areas. Soil conservation in the mountain zone, water yield in the oasis zone, and sand fixation in the desert zone all decreased under the influence of land use change alone. The warming-drying trend led to decreased water yield in the oasis zone and increased wind erosion in the desert zone. Based on the results, we recommend that local governments achieve sustainable use of ES by planting grasslands with high coverage in the oasis zone, increasing investment in agricultural science and technology, and establishing protected areas in the mountain and desert zones. The methodology in our study can also be applied to other regions with a MODS structure.

Uni-Directional Transportation on Peristome-Mimetic Surfaces for Completely Wetting Liquids.

Liquid uni-directional transport on solid surface without energy input would advance a variety of applications, such as in bio-fluidic devices, self-lubrication, and high-resolution printing. Inspired by the liquid uni-directional transportation on the peristome surface of Nepenthes alata, here, we fabricated a peristome-mimicking surface through high-resolution stereo-lithography and demonstrated the detailed uni-directional transportation mechanism from a micro-scaled view visualized through X-ray microscopy. Significantly, an overflow-controlled liquid uni-directional transportation mechanism is proposed and demonstrated. Unlike the canonical predictions for completely wetting liquids spreading symmetrically on a high-energy surface, liquids with varied surface tensions and viscosities can spontaneously propagate in a single preferred direction and pin in all others. The fundamental understanding gained from this robust system enabled us to tailor advanced micro-computerized tomography scanning and stereo-lithography fabrication to mimic natural creatures and construct a wide variety of fluidic machines out of traditional materials.

Comparative metabolism of tussilagone in rat and human liver microsomes using ultra-high-performance liquid chromatography coupled with high-resolution LTQ-Orbitrap mass spectrometry.

RATIONALE: Tussilagone is a major component in Tussilago farfara that has been widely used as an anti-tussive herbal medicine for the treatment of bronchitis, cough and asthmatic disorders in the clinic. However, its metabolism has been poorly investigated. In order to clarify its in vitro metabolism, a comparative analysis of its metabolic profile in rat liver microsomes (RLMs) and human liver microsomes (HLMs) was carried out. Further, the cytochrome P450 isoforms (CYPs) involved in the metabolism were investigated. METHODS: In this work, the biotransformation of tussilagone in RLMs and HLMs was compared using ultra-high-performance liquid chromatography coupled with high-resolution LTQ-Orbitrap mass spectrometry (UHPLC/HRMS) and the CYPs involved in the metabolism were further investigated by recombinant human CYP enzymes. RESULTS: Totally, nine metabolites of tussilagone were identified in RLMs and HLMs based on the proposed MS/MS fragmentation pathways of tussilagone and the accurate MS/MS spectra. Among them, one metabolite (M9) was detected in both RLMs and HLMs while the other eight metabolites were only detected in HLMs. Three hydroxylation metabolites (M6, M7 and M8) were detected in the assay with individual recombinant P450s incubation. M6 was detected in all CYPs except CYP2A6 while M7 and M8 were only observed in CYP3A4. CONCLUSIONS: The HR-ESI-MS/MS fragmentation behavior of tussilagone and its metabolic profile in RLMs and HLMs were investigated for the first time. The results demonstrated that the biotransformation of tussilagone involved hydrolysis of ester bonds at C-14 and hydroxylation in the side chains at C-12, C-5' or C-6'. Among the CYPs, CYP3A4 played an important role in the hydroxylation reaction of tussilagone in vitro. Furthermore, the results indicated a species-related difference in the metabolism of tussilagone between RLMs and HLMs. This work provided basic information for the metabolism of tussilagone in RLMs and HLMs, which would help to better understand the pharmacological activities of tussilagone.

On the Relationship between Economic Development, Environmental Integrity and Well-Being: The Point of View of Herdsmen in Northern China Grassland.

Inner Mongolia is among the most important regions in terms of contribution to the socio-economic development of China. Furthermore, its grassland is a major ecological barrier for Northern China. The present study evaluates the changes in ecosystem services availability and human wellbeing based on a survey on864 herdsmen of the grassland and 20 governmental officials. The survey provided the following results: (1) The supporting and provisioning services of the grassland have recently declined, thus affecting the herdsmen's wellbeing. The intensity of grazing, coal exploitation and tourism development heavily limits the availability of ecosystem services, among which provisioning ones are perceived as the most important. Below a certain threshold, grazing and mining are likely to promote the improvement of herdsmen's wellbeing, while trespassing that point, the enhancement of the herdsmen's living standards is curbed. (2) The herdsmen's cultural exchange, health conditions and social relations are better now than before; however, the threats on herdsmen's health and safety have increased. (3) A better income is among the most urgent herdsmen's needs. Livestock revenues did not increase at the same rate as the damage to the grassland and human risk exposure did. (4) The governmental ecological compensation policy did not entirely solve the problem of grassland desertification and environmental degradation, although it is also true that the degree of implementation and effectiveness of government policies is related to the still insufficient herdsmen's understanding and acceptance of these policies.

UPLC-MS method for quantification of pterostilbene and its application to comparative study of bioavailability and tissue distribution in normal and Lewis lung carcinoma bearing mice.

A UPLC-MS method was developed for determination of pterostilbene (PTS) in plasma and tissues of mice. PTS was separated on Agilent Zorbax XDB-C18 column (50 × 2.1 mm, 1.8 µm) with gradient mobile phase at the flow rate of 0.2 ml/min. The detection was performed by negative ion electrospray ionization in multiple reaction monitoring mode. The linear calibration curve of PTS in mouse plasma and tissues ranged from 1.0 to 5000 and 0.50 to 500 ng/ml (r(2)>0.9979), respectively, with lowest limits of quantification (LLOQ) were between 0.5 and 2.0 ng/ml, respectively. The accuracy and precision of the assay were satisfactory. The validated method was applied to the study of bioavailability and tissue distribution of PTS in normal and Lewis lung carcinoma (LLC) bearing mice. The bioavailability of PTS (dose 14, 28 and 56 mg/kg) in normal mice were 11.9%, 13.9% and 26.4%, respectively; and the maximum level (82.1 ± 14.2 µg/g) was found in stomach (dose 28 mg/kg). The bioavailability, peak concentration (Cmax), time to peak concentration (Tmax) of PTS in LLC mice was increased compared with normal mice. The results indicated the UPLC-MS method is reliable and bioavailability and tissue distribution of PTS in normal and LLC mice were dramatically different.

UHPLC-MS method for determination of gambogic acid and application to bioavailability, pharmacokinetics, excretion and tissue distribution in rats.

A sensitive ultrahigh performance liquid chromatography tandem mass spectrometry (UHPLC-MS) method was developed for determination of gambogic acid (GA) in rat plasma, urine, bile and main tissues. GA was separated on an Agilent Zorbax XDB-C18 column (50 × 2.1 mm, 1.8 µm) with gradient mobile phase at the flow rate of 0.2 mL/min. The detection was performed by negative electrospray ionization with multiple reaction monitoring mode. The calibration curves of GA were linear between 1.0 and 1000 ng/mL in rat plasma and bile and between 1.0 and 500 ng/mL in urine and tissues. The lowest limit of quantification for all matrices was 1.0 ng/mL. Both accuracy and precision of the assay were satisfactory. This validated method was firstly applied to bioavailability (BA), pharmacokinetics, excretion and tissue distribution in rats. The BAs of GA (40 and 80 mg/kg) in rats were 0.25 and 0.32%, respectively. GA was distributed extensively in rats after oral administration and exhibited the highest level in liver. GA reached the cumulative excretion amount of 25.3 ± 1.7 µg in bile and 0.275 ± 0.08 µg in urine after i.g. 80 mg/kg to rats at 24 h. The present results would be helpful for further clinical use of GA as a potential anticancer drug.

Application of a sensitive and specific LC-MS/MS method for determination of eriodictyol-8-C-ß-d-glucopyranoside in rat plasma for a bioavailability study.

This study is the first to detail the development and validation of a rapid, sensitive and specific LC-ESI-MS/MS method for the determination of eriodictyol-8-C-ß-d-glucopyranoside (EG) in rat plasma. A simple protein precipitation method was used for plasma sample preparation. Chromatographic separation was successfully achieved on an Agilent Zorbax XDB C18 column (2.1 × 50 mm, 3.5 µm) using a step gradient program with the mobile phase of 0.1% formic acid aqueous solution and acetonitrile with 0.1% formic acid. EG and the internal standard (IS) were detected using an electrospray negative ionization mass spectrometry in the multiple reaction monitoring mode. This method demonstrated good linearity and did not show any endogenous interference with the active compound and IS peaks. The lower limit of quantification of EG was 0.20 ng/mL in 50 µL rat plasma. The average recoveries of EG and IS from rat plasma were both above 80%. The inter-day precisions (relative standard deviation) of EG determined over 5 days were all within 15%. The present method was successfully applied to a quantification and bioavailability study of EG in rats after intravenous and oral administration. The oral absolute bioavailability of EG in rats was estimated to be 7.71 ± 1.52%.

LC-ESI-MS/MS analysis and pharmacokinetics of plantainoside D isolated from Chirita longgangensis var. hongyao, a potential anti-hypertensive active component in rats.

Plantainoside D (PD) is a potential anti-hypertensive active ingredient newly isolated from the dried plants of Chirita longgangensis var. hongyao. A sensitive and specific LC-ESI-MS/MS method was first developed and validated for the analysis of PD in rat plasma using genistein as the internal standard (IS). The plasma samples were pretreated with methanol-acetonitrile (50:50, v/v) to precipitate protein, and then chromatographed on a reverse-phase Agilent Zorbax XDB C18 column (50 mm × 2.1 mm, 3.5 µm). Gradient elution was utilized, with a mobile phase consisting of water and acetonitrile both containing 0.1% formic acid, and the flow rate was set at 0.50 mL/min. The analytes were monitored by tandem-mass spectrometry with negative electrospray ionization. The precursor/product transitions (m/z) in the negative ion mode were 639.2 → 160.9 Thomson (Th) and 268.9 → 158.9 Thomson (Th) for PD and IS, respectively. Linearity was achieved in the 0.10-200 ng/mL range, with a lower limit of quantification of 0.10 ng/mL. The precision and accuracy for both intra- and inter-day determination of the analyte were all within ±15%. The present method has been applied for pharmacokinetic study of PD after oral and intravenous administration in rats. The oral absolute bioavailability (F) of PD in rats was estimated to be 1.12% ± 0.46% with an elimination half-life (t1/2) value of 1.63 ± 0.19 h, suggesting its poor absorption and/or strong metabolism in vivo.

Pharmacokinetics of plantamajoside and acteoside from Plantago asiatica in rats by liquid chromatography-mass spectrometry.

Plantago asiatica is a medicinal and dietary plant rich in polyphenolic compounds such as phenylpropanoid glycosides plantamajoside and acteoside. The aims of the present study were to develop a new and sensitive method for simultaneous determination of plantamajoside and acteoside and investigate their pharmacokinetic properties in rats. A sensitive and rapid liquid chromatography-tandem mass spectrometry (LC-MS/MS) method with multiple-reaction monitoring (MRM) mode was employed for quantification of two analytes in rat plasma. The calibration curve was linear over the range of 0.2-200ng/ml with correlation coefficient greater than 0.9983 for both analytes. The accuracy of plantamajoside and acteoside were between -4.2% and 8.1%, -3.8% and 8.9% relative error, respectively. Precision for the two analytes ranged from 2.7 to 10.2% relative standard deviation. The pharmacokinetic results showed plantamajoside and acteoside were quickly absorbed in rat with the time to maximum plasma concentration 16.7±2.8 and 13.3±2.8min, respectively. The elimination constants were 0.28±0.01 1h(-1) for plantamajoside and 0.47±0.03 1h(-1) for acteoside. The developed method and the pharmacokinetic data provide a basis for further studies on bioactivity of P. asiatica.

Interactive effects of warming and increased precipitation on community structure and composition in an annual forb dominated desert steppe.

To better understand how warming, increased precipitation and their interactions influence community structure and composition, a field experiment simulating hydrothermal interactions was conducted at an annual forb dominated desert steppe in northern China over 2 years. Increased precipitation increased species richness while warming significantly decreased species richness, and their effects were additive rather than interactive. Although interannual variations in weather conditions may have a major affect on plant community composition on short term experiments, warming and precipitation treatments affected individual species and functional group composition. Warming caused C4 grasses such as Cleistogenes squarrosa to increase while increased precipitation caused the proportions of non-perennial C3 plants like Artemisia capillaris to decrease and perennial C4 plants to increase.

Organic carbon storage in four ecosystem types in the karst region of southwestern China.

Karst ecosystems are important landscape types that cover about 12% of the world's land area. The role of karst ecosystems in the global carbon cycle remains unclear, due to the lack of an appropriate method for determining the thickness of the solum, a representative sampling of the soil and data of organic carbon stocks at the ecosystem level. The karst region in southwestern China is the largest in the world. In this study, we estimated biomass, soil quantity and ecosystem organic carbon stocks in four vegetation types typical of karst ecosystems in this region, shrub grasslands (SG), thorn shrubbery (TS), forest - shrub transition (FS) and secondary forest (F). The results showed that the biomass of SG, TS, FS, and F is 0.52, 0.85, 5.9 and 19.2 kg m(-2), respectively and the corresponding organic cabon storage is 0.26, 0.40, 2.83 and 9.09 kg m(-2), respectively. Nevertheless, soil quantity and corresponding organic carbon storage are very small in karst habitats. The quantity of fine earth overlaying the physical weathering zone of the carbonate rock of SG, TS, FS and F is 38.10, 99.24, 29.57 and 61.89 kg m(-2), respectively, while the corresponding organic carbon storage is only 3.34, 4.10, 2.37, 5.25 kg m(-2), respectively. As a whole, ecosystem organic carbon storage of SG, TS, FS, and F is 3.81, 4.72, 5.68 and 15.1 kg m(-2), respectively. These are very low levels compared to other ecosystems in non-karst areas. With the restoration of degraded vegetation, karst ecosystems in southwestern China may play active roles in mitigating the increasing CO2 concentration in the atmosphere.