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Understanding the near-ground vertical and temporal photochemical O3 formation mechanism is important to mitigate O3 pollution. Here, we measured the vertical profiles of O3 and its precursors at six different heights, ranging from 5 to 335 m, using a newly built vertical observation system in the Pearl River Delta (PRD) region of China. The net photochemical ozone production rate (P(O3)net) and O3 formation sensitivities at various heights were diagnosed using an observation-based model coupled with the Master Chemical Mechanism (MCM v3.3.1). Moreover, to assess model performance and identify the causative factors behind O3 pollution episodes, the P(O3)net was measured at 5 m above ground level with a custom-built detection system. In total, three O3 pollution episodes and two non-episodes were captured. The identified O3 pollution episodes were found to be jointly influenced by both photochemical production and physical transport, with local photochemical reactions playing a major role. The high index of agreement (IOA) calculated by comparing the modelled and measured P(O3)net values indicated the rationality of investigating the vertical and temporal variability in O3 formation mechanisms using model results. However, the measured P(O3)net values were generally higher than the modelled P(O3)net values, particularly under high-NOx conditions, which may indicate a potential underestimation of total RO2 by the model. Throughout the measurement period, the contribution of different reaction pathways to O3 production remained consistent across various heights, with HO2 + NO as the major O3 production pathway, followed by RO2 + NO. We observed that P(O3)net decreased with an increase in measurement height, which was primarily attributed to the reduction in O3 precursors, such as oxygenated volatile organic compounds (OVOCs) and non-methane hydrocarbons (NMHCs). The O3 formation regimes were similar at different heights during both episodes and non-episodes, either being located in the VOC-sensitive regime or in the transition regime that is more sensitive to VOCs. Diurnally, photochemical O3 formation typically remained in the VOC-sensitive regime during the morning and noon, but it transitioned to the transition regime and was more sensitive to VOCs in the afternoon at around 16:00 LT (local time). Vertical and temporal photochemical O3 formation is most sensitive to OVOCs, suggesting that targeting specific VOCs for control measures is more practical and feasible at the observation site. The vertical temporal analysis of O3 formation mechanisms near the ground surface in this study provides critical foundational knowledge that can be used to formulate effective short-term emergency and long-term control strategies to combat O3 pollution in the PRD region of China.

Plant phenology refers to cyclic plant growth events, and is one of the most important indicators of climate change. Integration of plant phenology information is crucial for understanding the ecosystem response to global change and modeling the material and energy balance of terrestrial ecosystems. Utilizing 24 552 in situ phenological observations of 24 representative woody plant species from the Chinese Phenology Observation Network (CPON), we have developed maps delineating species phenology (SP) and ground phenology (GP) of forests over China from 1951 to 2020. These maps offer a detailed spatial resolution of 0.1∘ and a temporal resolution of 1 d. Our method involves a model-based approach to upscale in situ phenological observations to SP maps, followed by the application of weighted average and quantile methods to derive GP maps from the SP data. The resulting SP maps for the 24 woody plants exhibit a high degree of concordance with in situ observations, manifesting an average deviation of 6.9 d for spring and 10.8 d for autumn phenological events. Moreover, the GP maps demonstrate robust alignment with extant land surface phenology (LSP) products sourced from remote sensing data, particularly within deciduous forests, where the average discrepancy is 8.8 d in spring and 15.1 d in autumn. This dataset provides an independent and reliable phenology data source for China on a long-time scale of 70 years, and contributes to more comprehensive research on plant phenology and climate change at both regional and national scales. The dataset can be accessed at https://doi.org/10.57760/sciencedb.07995 (Zhu and Dai, 2023).

Surgical resection remains the prefer option for bladder cancer treatment. However, the effectiveness of surgery is usually limited for the high recurrence rate and poor prognosis. Consequently, intravesical chemotherapy synergize with immunotherapy in situ is an attractive way to improve therapeutic effect. Herein, a combined strategy based on thermo-sensitive PLEL hydrogel drug delivery system was developed. GEM loaded PLEL hydrogel was intravesical instilled to kill tumor cells directly, then PLEL hydrogel incorporated with CpG was injected into both groins subcutaneously to promote immune responses synergize with GEM. The results demonstrated that drug loaded PLEL hydrogel had a sol-gel phase transition behavior in response to physiological temperature and presented sustained drug release, and the PLEL-assisted combination therapy could have better tumor suppression effect and stronger immunostimulating effect in vivo. Hence, this combined treatment with PLEL hydrogel system has great potential and suggests a clinically-relevant and valuable option for bladder cancer.

Current process-based research mainly uses box models to evaluate photochemical ozone production and destruction rates, and it is unclear to what extent the photochemical reaction mechanisms are elucidated. Here, we modified and improved a net photochemical ozone production rate (NPOPR, P(O3)net) detection system based on the current dual-channel reaction chamber technique, which makes the instrument applicable to different ambient environments, and its various operating indicators were characterized, i.e., “airtightness”, light transmittance, wall losses of the reaction and reference chambers, conversion rate of O3 to NO2, air residence time, and performance of the reaction and reference chambers. The limits of detection of the NPOPR detection system were determined to be 0.07, 1.4, and 2.3 ppbv h−1 at sampling flow rates of 1.3, 3, and 5 L min−1, respectively. We further applied the NPOPR detection system to field observations at an urban site in the Pearl River Delta (China). During the observation period, the maximum value of P(O3)net was 34.1 ppbv h−1, which was ∼ 0 ppbv h−1 at night within the system detection error and peaked at approximately noon local time. The daytime (from 06:00–18:00 LT) average value of P(O3)net was 12.8 (± 5.5) ppbv h−1. We investigated the detailed photochemical O3 formation mechanism in the reaction and reference chambers of the NPOPR detection system using a zero-dimensional box model. We found that the photochemical reactions in the reaction chamber were very close to those in ambient air, but there was not zero chemistry in the reference chamber because the reaction related to the production and destruction of RO2 (= HO2 + RO2) continued in the reference chamber, which led to a small amount of P(O3)net. Therefore, the P(O3)net measured here can be regarded as the lower limit of the real P(O3)net in the atmosphere; however, the measured P(O3)net was still ∼ 7.5 to 9.3 ppbv h−1 higher than the modeled P(O3)net value depending on different modeling methods, which may be due to the inaccurate estimation of HO2 / RO2 radicals in the modeling study. Short-lived intermediate measurements coupled with direct P(O3)net measurements are needed in the future to better understand O3 photochemistry. Our results show that the NPOPR detection system can achieve high temporal resolution and continuous field observations, which helps us to better understand photochemical O3 formation and provides a key scientific basis for continuous improvement of air quality in China.

The mixing of oil and gas forms the foundation of deep-sea oil and gas extraction and transportation. However, traditional conveying equipment has low efficiency and high failure rates. In this study, a spiral axial flow gas and liquid multiphase pump was used as the base model. The Eulerian multiphase flow model and RNG turbulence model were used for numerical simulations to analyze the internal flow field of the multiphase pump. A modification scheme was proposed to twist the airfoil shape and create a twisted vane. The twisted blade with the center of the hub-side flange chord length as the twisting center was twisted in the counterclockwise direction to help reduce the relative volume of gas in the flow channel. When the twisted vane with the hub-side airfoil type trailing edge point as the twisting center was twisted in the suction side direction, it helped to accelerate the movement of the gas-liquid mixture at the trailing edge of the back of the vane and further reduced the low velocity zone at the back of the vane. When the twist center is located at the hub side wing type trailing edge point of the twist vane, the twist degree is 0.214. This results in the maximum head and efficiency of the pump, improves gas phase aggregation phenomenon, and enhances the performance of the multiphase pump.

Low activation isotopic boron (11B) based magnesium diboride (Mg11B2) superconductors doped with biomass-derived activated carbon were synthesized using 11B and magnesium powder via solid-state reaction. The effect of carbon doping on the lattice structure and superconducting properties of Mg11B2 bulks were evaluated using X-ray powder diffraction, high resolution transmission electron microscopy, scanning electron microscopy and magnetization measurements. Precise refinement of structural parameters indicates successful substitution of carbon in Mg11B2 bulks. The critical current density (Jc) of carbon doped Mg11B2 synthesized at 650 °C was enhanced more than two times compared with the pure Mg11B2 bulk. Similar improvement was observed for the Mg11B2 bulks heat-treated at 800 °C. This enhancement is due to successful substitution of biomass-derived carbon with high surface area into Mg11B2 lattice. The flux pinning mechanism of pure and doped Mg11B2 bulks were investigated using the Dew-Hughes model. This study provides information regarding enhancement of the Jc of low activation Mg11B2 superconductors suitable for next-generation fusion magnets.

Coordinated control of fine particulate matter (PM2.5) and ozone (O3) has become a new and urgent issue for China's air pollution control. Biogenic volatile organic compounds (BVOCs) are important precursors of O3 and secondary organic aerosol (SOA) formation. China experienced a rapid increase in BVOC emissions as a result of increased vegetation biomass. We applied WRF-Chem3.8 coupling with MEGAN2.1 to conduct long-term simulations for impacts of BVOC emissions on O3 and SOA during 1981–2018, using the emission factors extrapolated by localized emission rates and annual vegetation biomass. In summer 2018, BVOC emissions were 9.91 Tg (in June), which led to an average increase of 8.6 ppb (16.75 % of the total) in daily maximum 8 h (MDA8) O3 concentration and 0.84 µg m−3 (73.15 % of the total) in SOA over China. The highest contribution to O3 is concentrated in the Great Khingan Mountains, Qinling Mountains, and most southern regions while in southern areas for SOA. Isoprene has the greatest contribution to O3, while monoterpene has the largest SOA production. BVOC emissions have distinguished impacts in different regions. The Chengdu–Chongqing (CC) region has the highest O3 and SOA generated by BVOCs, while the Beijing–Tianjin–Hebei (BTH) region has the lowest. From 1981 to 2018, the interannual variation of BVOC emissions caused by increasing leaf biomass resulted in O3 concentration increasing by 7.38 % at an average rate of 0.11 ppb yr−1 and SOA increasing by 39.30 % at an average rate of 0.008 µg m−3 yr−1. Due to the different changing trends of leaf biomass by region and vegetation type, O3 and SOA show different interannual variations. The Fenwei Plain (FWP), Yangtze River Delta (YRD), and Pearl River Delta (PRD) regions have the most rapid O3 increment, while the increasing rate of SOA in CC is the highest. BTH has the smallest enhancement in O3 and SOA concentration. This study will help to recognize the impact of historical BVOC emissions on O3 and SOA and further provide a reliable scientific basis for the precise prevention and control of air pollution in China.

With the global climate change and rapid urbanization, urban flood disasters spread and become increasingly serious in China. Urban rainstorms and waterlogging have become an urgent challenge that needs to be monitored in real time and further predicted for the improvement of urbanization construction. We trained a recurrent neural network (RNN) model to classify microblogging posts related to urban waterlogging and establish an online monitoring system of urban waterlogging caused by flood disasters. We manually curated more than 4400 waterlogging posts to train the RNN model so that it can precisely identify waterlogging-related posts of Sina Weibo to timely determine urban waterlogging. The RNN model has been thoroughly evaluated, and our experimental results showed that it achieved higher accuracy than traditional machine learning methods, such as the support vector machine (SVM) and gradient boosting decision tree (GBDT). Furthermore, we build a nationwide map of urban waterlogging based on recent 2-year microblogging data.

We present multi-period modulation of energetic electron flux observed by the BeiDa Imaging Electron Spectrometer (BD-IES) on board a Chinese navigation satellite on 13 October 2015. Electron flux oscillations were observed at a dominant period of ∼190 s in consecutive energy channels from ∼50 to ∼200 keV. Interestingly, flux modulations at a secondary period of ∼400 s were also unambiguously observed. The oscillating signals at different energy channels were observed in sequence, with a time delay of up to ∼900 s. This time delay far exceeds the oscillating periods, by which we speculate that the modulations were caused by localized ultra-low-frequency (ULF) waves. To verify the wave–particle interaction scenario, we revisit the classic drift-resonance theory. We adopt the calculation method therein to derive the electron energy change in a multi-period ULF wave field. Then, based on the modeled energy change, we construct the flux variations to be observed by a virtual spacecraft. The predicted particle signatures well agree with the BD-IES observations. We demonstrate that the particle energy change might be underestimated in the conventional theories, as the Betatron acceleration induced by the curl of the wave electric field was often omitted. In addition, we show that azimuthally localized waves would notably extend the energy width of the resonance peak, whereas the drift-resonance interaction is only efficient for particles at the resonant energy in the original theory.

Southeast Asian peatland-draining rivers have attracted much attention due to their high dissolved organic carbon (DOC) yield and high CO2 emissions under anthropogenic influences. In August 2016, we carried out a field investigation of the Rajang River and its estuary, a tropical system located in Sarawak, Malaysia. The Rajang has peatland in its estuary, while the river basin is covered by tropical rainforest. DOC-δ13C in the Rajang ranged from −28.7 ‰ to −20.1 ‰, with a U-shaped trend from river to estuary. For particulate organic carbon (POC), δ13C ranged between −29.4 ‰ and −31.1 ‰ in the river, and there was a clear increasing trend towards more enriched δ13C values with higher salinity. In the estuary, there was a linear conservative dilution pattern for dissolved organic matter composition (as quantified by D- and L-amino acid enantiomers) plotted against DOC-δ13C, whereas when plotted against salinity, dissolved D- and L-amino acid enantiomer values were higher than the theoretical dilution value. Together, these data indicate that the addition of DOC to the estuary (by peatland) not only increased the DOC concentration but also altered its composition, by adding more biodegraded, 13C-depleted organic matter into the bulk dissolved organic matter. Alteration of organic matter composition (addition of a more degraded subpart) was also apparent for the particulate phase, but patterns were less clear. The Rajang was characterized by DOC to DON (dissolved organic nitrogen) ratios of 50 in the river section, with loss of DON in the estuary increasing the ratio to 140, suggesting an unbalanced export of organic carbon and nitrogen. Where affected by anthropogenic activities, further assessment of organic carbon to nitrogen ratios is needed.

Mirror-mode structures widely exist in various space plasma environments. Here, we investigate a train of mirror-mode structures in the terrestrial plasma sheet on 11 August 2017 based on the Magnetospheric Multiscale mission. We find that bipolar current densities exist in the cross section of two hole-like mirror-mode structures, referred to as magnetic dips. The bipolar current density in the magnetic dip with a size of ∼2.2 ρi (the ion gyro radius) is mainly contributed by variations of the electron velocity, which is mainly formed by the magnetic gradient–curvature drift. For another magnetic dip with a size of ∼6.6 ρi, the bipolar current density is mainly caused by an ion bipolar velocity, which can be explained by the collective behaviors of the ion drift motions. The current density inside the mirror dip contributes to the maintenance of the hole-like structure's stable. Our observations suggest that the electrons and ions play different roles in the formation of currents in magnetic dips with different sizes.

To quantify climate change impact and difference on basin-scale river runoff under the limiting global warming thresholds of 1.5 and 2.0 ∘C, this study examined four river basins covering a wide hydroclimatic setting. We analyzed projected climate change in four basins, quantified climate change impact on annual and seasonal runoff based on the Soil Water Assessment Tool, and estimated the uncertainty constrained by the global circulation model (GCM) structure and the representative concentration pathways (RCPs). All statistics for the two river basins (the Shiyang River, SYR, and the Chaobai River, CBR) located in northern China indicated generally warmer and wetter conditions, whereas the two river basins (the Huaihe River, HHR, and the Fujiang River, FJR) located in southern China projected less warming and were inconsistent regarding annual precipitation change. The simulated changes in annual runoff were complex; however, there was no shift in seasonal runoff pattern. The 0.5 ∘C global warming difference resulted in 0.7 and 0.6 ∘C warming in basins in northern and southern China, respectively. This led to a projected precipitation increase by about 2 % for the four basins and to a decrease in simulated annual runoff of 8 % and 1 % in the SYR and the HHR, respectively, but to an increase of 4 % in the CBR and the FJR. The uncertainty in projected annual temperature was dominated by the GCMs or the RCPs; however, that of precipitation was constrained mainly by the GCMs. The 0.5 ∘C difference decreased the uncertainty in the annual precipitation projection and the annual and monthly runoff simulation.

Peatlands are a large source of methane (CH4) to the atmosphere, yet the uncertainty around the estimates of CH4 flux from peatlands is large. To better understand the spatial heterogeneity in temperate peatland CH4 emissions and their response to physical and biological drivers, we studied CH4 dynamics throughout the growing seasons of 2017 and 2018 in Flatiron Lake Bog, a kettle-hole peat bog in Ohio. The site is composed of six different hydro-biological zones: an open water zone, four concentric vegetation zones surrounding the open water, and a restored zone connected to the main bog by a narrow channel. At each of these locations, we monitored water level (WL), CH4 pore-water concentration at different peat depths, CH4 fluxes from the ground and from representative plant species using chambers, and microbial community composition with a focus here on known methanogens and methanotrophs. Integrated CH4 emissions for the growing season were estimated as 315.4±166 mgCH4m-2d-1 in 2017 and 362.3±687 mgCH4m-2d-1 in 2018. Median CH4 emission was highest in the open water, then it decreased and became more variable through the concentric vegetation zones as the WL dropped, with extreme emission hotspots observed in the tamarack mixed woodlands (Tamarack) and low emissions in the restored zone (18.8–30.3 mgCH4m-2d-1). Generally, CH4 flux from above-ground vegetation was negligible compared to ground flux ( %), although blueberry plants were a small CH4 sink. Pore-water CH4 concentrations varied significantly among zones, with the highest values in the Tamarack zone, close to saturation, and the lowest values in the restored zone. While the CH4 fluxes and pore-water concentrations were not correlated with methanogen relative abundance, the ratio of methanogens to methanotrophs in the upper portion of the peat was significantly correlated to CH4 transfer velocity (the CH4 flux divided by the difference in CH4 pore-water concentration between the top of the peat profile and the concentration in equilibrium with the atmosphere). Since ebullition and plant-mediated transport were not important sources of CH4 and the peat structure and porosity were similar across the different zones in the bog, we conclude that the differences in CH4 transfer velocities, and thus the flux, are driven by the ratio of methanogen to methanotroph relative abundance close to the surface. This study illustrates the importance of the interactions between water-level and microbial composition to better understand CH4 fluxes from bogs and wetlands in general.

Improving the accuracy of the anthropogenic volatile organic compound (VOC) emission inventory is essential for reducing air pollution. In this study, we established an emission inventory of anthropogenic VOCs in the Beijing–Tianjin–Hebei (BTH) region of China for 2015 based on the emission factor (EF) method. Online ambient VOC observations were conducted in one urban area of Beijing in January, April, July, and October, which, respectively, represented winter, spring, summer, and autumn in 2015. Furthermore, the developed emission inventory was evaluated by a comprehensive verification system based on the measurements and satellite retrieval results. Firstly, emissions of the individual species of the emission inventory were evaluated according to the ambient measurements and emission ratios versus carbon monoxide (CO). Secondly, the source structure of the emission inventory was evaluated using source appointment with the Positive Matrix Factorization (PMF) model. Thirdly, the spatial and temporal distribution of the developed emission inventory was evaluated by a satellite-derived emission inventory. According to the results of the emission inventory, the total anthropogenic VOC emissions in the BTH region were 3277.66 Gg in 2015. Online measurements showed that the average mixing ratio of VOCs in Beijing was approximately 49.94 ppbv in 2015, ranging from 10.67 to 245.54 ppbv. The annual emissions for 51 of 56 kinds of non-methane hydrocarbon species derived from the measurements agreed within ±100 % with the results of the emission inventory. Based on the PMF results and the emission inventory, it is evident that vehicle-related emissions dominate the composition of anthropogenic VOCs in Beijing. The spatial correlation between the emission inventory and satellite inversion result was significant (p) with a correlation coefficient of 0.75. However, there were discrepancies between the relative contributions of fuel combustion, emissions of oxygenated VOCs (OVOCs), and halocarbons from the measurements and inventory. To obtain a more accurate emission inventory, we propose the investigation of the household coal consumption, the adjustment of EFs based on the latest pollution control policies, and the verification of the source profiles of OVOCs and halocarbons.

Synthetic Aperture Radar (SAR) plays an important role in the classification and recognition of ship targets because of its all-weather working ability and fine resolution. In SAR images, besides the sea clutter, the influence of the sea surface on the radar echo is also known as the so-called multipath effect. These multipath effects will generate some extra "pseudo images", which may cause the distortion of the target image and affect the estimation of the characteristic parameters. In this paper,the multipath effect of rough sea surface and its influence on the estimation of ship characteristic parameters are studied. The imaging of the first and the secondary reflection of sea surface is presented . The artifacts not only overlap with the image of the target itself, but may also appear in the sea near the target area. It is difficult to distinguish them, and this artifact has an effect on the length and width of the ship.

Hyperspectral remote sensing is a completely non-invasive technology for measurement of cultural relics, and has been successfully applied in identification and analysis of pigments of Chinese historical paintings. Although the phenomenon of mixing pigments is very usual in Chinese historical paintings, the quantitative analysis of the mixing pigments in the ancient paintings is still unsolved. In this research, we took two typical mineral pigments, vermilion and stone yellow as example, made precisely mixed samples using these two kinds of pigments, and measured their spectra in the laboratory. For the mixing spectra, both fully constrained least square (FCLS) method and derivative of ratio spectroscopy (DRS) were performed. Experimental results showed that the mixing spectra of vermilion and stone yellow had strong nonlinear mixing characteristics, but at some bands linear unmixing could also achieve satisfactory results. DRS using strong linear bands can reach much higher accuracy than that of FCLS using full bands.

The Hippo pathway is a major orchestrator of organ development and homeostasis. Here Azad and colleagues develop a biosensor to monitor the activity of the Hippo pathway component LATS and identify VEGF signalling as an upstream regulator of LATS, supporting a role for Hippo signalling during angiogenesis.

Low temperature plasma (LTP) has emerged as a new research hotspot of promising therapy to fight against cancer. Autophagy is a multifunctional process that digests and recycles cellular contents within lysosomes to maintain homeostasis, which is the underlying mechanism of cancer cell death and anti-cancer treatment. This study aimed at investigating whether autophagy of HepG2 cells could be induced by LTP and revealing the related molecular mechanism. For this purpose, the atmospheric pressure plasma jet (APPJ) in helium was utilized to generate plasma-actived medium (PAM) to treat HepG2 cells in vitro. Catalase (CAT), superoxide dismutase (SOD) and 3-methyladenine (3-MA) were respectively added into the PAM as the intervention group. The cell viability, formation of autophagosomes, intracellular reactive oxygen species (ROS) level, expression levels of autophagy-associated proteins and key proteins involved in PI3K/AKT/mTOR pathways were detected. The results showed that LTP inhibited cell viability in a dose- and time-dependent manner. Autophagy was induced through the formation of autophagosomes, conversion of LC3-II/LC3-I, increased expression of beclin 1 and degradation of p62. The mechanism was deduced that LTP enhanced the intracellular ROS level and decreased the phosphorylation level of key proteins in PI3K/AKT/mTOR/p70S6K pathway. However, these effects were blocked by the autophagy inhibitor 3-MA and ROS scavengers (CAT and SOD). The therapeutic efficacy of LTP against HepG2 cells may involve autophagy via suppressing PI3K/AKT/mTOR signaling pathway by LTP-mediated ROS.

This paper describes a new modeling framework for microscopic to reservoir-scale simulations of hydraulic fracturing and production. The approach builds upon a fusion of two existing high-performance simulators for reservoir-scale behavior: the GEOS code for hydromechanical evolution during stimulation and the TOUGH+ code for multi-phase flow during production. The reservoir-scale simulations are informed by experimental and modeling studies at the laboratory scale to incorporate important micro-scale mechanical processes and chemical reactions occurring within the fractures, the shale matrix, and at the fracture-fluid interfaces. These processes include, among others, changes in stimulated fracture permeability as a result of proppant behavior rearrangement or embedment, or mineral scale precipitation within pores and microfractures, at µm to cm scales. In our new modeling framework, such micro-scale testing and modeling provides upscaled hydromechanical parameters for the reservoir scale models. We are currently testing the new modeling framework using field data and core samples from the Hydraulic Fracturing Field Test (HFTS), a recent field-based joint research experiment with intense monitoring of hydraulic fracturing and shale production in the Wolfcamp Formation in the Permian Basin (USA). Below, we present our approach coupling the reservoir simulators GEOS and TOUGH+ informed by upscaled parameters from micro-scale experiments and modeling. We provide a brief overview of the HFTS and the available field data, and then discuss the ongoing application of our new workflow to the HFTS data set.

A longstanding puzzle in isotope studies of C3 plant species is that heterotrophic plant organs (e.g., stems, roots, seeds, and fruits) tend to be enriched in 13C compared to the autotrophic organ (leaves) that provides them with photosynthate. Our inability to explain this puzzle suggests key deficiencies in understanding post-photosynthetic metabolic processes. It also limits the effectiveness of applications of stable carbon isotope analyses in a variety of scientific disciplines ranging from plant physiology to global carbon cycle studies. To gain insight into this puzzle, we excavated whole plant architectures of Nitraria tangutorum Bobrov, a C3 species that has an exceptional capability of fixing sands and building sand dunes, in two deserts in northwestern China. We systematically and simultaneously measured carbon isotope ratios and nitrogen and phosphorous contents of different parts of the excavated plants. We also determined the seasonal variations in leaf carbon isotope ratios on nearby intact plants of N. tangutorum. We found, for the first time, that higher nitrogen contents in heterotrophic organs were significantly correlated with increased heterotrophic 13C enrichment compared to leaves. However, phosphorous contents had no effect on the enrichment. In addition, new leaves had carbon isotope ratios similar to roots but were progressively depleted in 13C as they matured. We concluded that a nitrogen-mediated process, hypothesized to be the refixation of respiratory CO2 by phosphoenolpyruvate (PEP) carboxylase, was responsible for the differences in 13C enrichment among different heterotrophic organs, while processes such as fractionating foliar metabolism and preferentially loading into phloem of 13C-enriched sugars may contribute to the overall autotrophic–heterotrophic difference in carbon isotope compositions.

Terrestrial carbon and water cycles are interactively linked at various spatial and temporal scales. Evapotranspiration (ET) plays a key role in the terrestrial water cycle, altering carbon sequestration of terrestrial ecosystems. The study of ET and its response to climate and vegetation changes is critical in China because water availability is a limiting factor for the functioning of terrestrial ecosystems in vast arid and semiarid regions. To constrain uncertainties in ET estimation, the process-based Boreal Ecosystem Productivity Simulator (BEPS) model was employed in conjunction with a newly developed leaf area index (LAI) data set, MODIS land cover, meteorological, and soil data to simulate daily ET and water yield at a spatial resolution of 500 m over China for the period from 2000 to 2010. The spatial and temporal variations of ET and water yield were analyzed. The influences of climatic factors (temperature and precipitation) and vegetation (land cover types and LAI) on these variations were assessed. Validations against ET measured at five ChinaFLUX sites showed that the BEPS model was able to simulate daily and annual ET well at site scales. Simulated annual ET exhibited a distinguishable southeast to northwest decreasing gradient, corresponding to climate conditions and vegetation types. It increased with the increase of LAI in 74% of China's landmass and was positively correlated with temperature in most areas of southwest, south, east, and central China. The correlation between annual ET and precipitation was positive in the arid and semiarid areas of northwest and north China, but negative in the Tibetan Plateau and humid southeast China. The national annual ET varied from 345.5 mm in 2001 to 387.8 mm in 2005, with an average of 369.8 mm during the study period. The overall rate of increase, 1.7 mm yr−1 (R2 = 0.18, p = 0.19), was mainly driven by the increase of total ET in forests. During 2006–2009, precipitation and LAI decreased widely and consequently caused a detectable decrease in national total ET. Annual ET increased over 62.2% of China's landmass, especially in the cropland areas of the southern Haihe River basin, most of the Huaihe River basin, and the southeastern Yangtze River basin. It decreased in parts of northeast, north, northwest, south China, especially in eastern Qinghai-Tibetan Plateau, the south of Yunnan Province, and Hainan Province. Reduction in precipitation and increase in ET caused vast regions in China, especially the regions south of Yangtze River, to experience significant decreases in water yield, while some sporadically distributed areas experienced increases in water yield. This study shows that the terrestrial water cycles in China's terrestrial ecosystems appear to have been intensified by recent climatic variability and human induced vegetation changes.

Free vibration equations for non-cylindrical (conical, barrel, and hyperboloidal types) helical springs with noncircular cross-sections, which consist of 14 first-order ordinary differential equations with variable coefficients, are theoretically derived using spatially curved beam theory. In the formulation, the warping effect upon natural frequencies and vibrating mode shapes is first studied in addition to including the rotary inertia, the shear and axial deformation influences. The natural frequencies of the springs are determined by the use of improved Riccati transfer matrix method. The element transfer matrix used in the solution is calculated using the Scaling and Squaring method and Pad'e approximations. Three examples are presented for three types of springs with different cross-sectional shapes under clamped-clamped boundary condition. The accuracy of the proposed method has been compared with the FEM results using three-dimensional solid elements (Solid 45) in ANSYS code. Numerical results reveal that the warping effect is more pronounced in the case of non-cylindrical helical springs than that of cylindrical helical springs, which should be taken into consideration in the free vibration analysis of such springs.

Beam-beam effects present one of the major factors limiting the luminosity of colliders. In the energy recovery linac (ERL) based eRHIC design, the electron beam, accelerated in a superconducting ERL, collides with the proton beam circulating in the RHIC ring. During such collisions the electron beam undergoes a very strong beam-beam interaction with the protons, which warrants careful examination. We evaluated transverse disruption and linear mismatch effects in the electron beam caused by collisions and considered several countermeasures to mitigate the emittance growth from these interactions. The minimum required aperture of transport lines is calculated that should allow the transport of the electron beam during the deceleration process.