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Sedimentary δDn-alkane value is widely utilized as a reliable proxy for paleo-hydrological reconstruction. Applications of this proxy must be based upon a globally clear understanding of the relationship between leaf wax δDn-alkane values and precipitation δD (δDp), defined as apparent fractionation (eapp). However, there is a critical concern about whether relatively constant eapp values exist across different latitudes. In this study, we systematically analyzed the variations of available eapp with latitudes based upon two compiled-new databases of higher plants and sediments over the world. We found that the total average eapp was relatively constant, i.e., −116 ± 5‰ (n = 941), in higher plants across different latitudes without consideration of plant types (e.g., dicots, monocots, gymnosperms), and was still constant but slightly lower average eapp, i.e., −125 ± 6‰ (n = 460), in sediments across the latitudes. The slightly lower average eapp in sediments relative to higher plants probably derived from the contribution of aquatic plants with isotopically D-depleted eapp in lake sediments. Interestingly, with consideration of plant types, average eapp increased in dicots but decreased in monocots slightly from low to high latitudes. The counteraction of these competing trends generates relatively constant average eapp values in higher plants, and resultantly constant average eapp values occur in sediments at the global scale. It is important to elaborate relatively constant eapp values from higher plants and sediments across different latitudes when sedimentary δDn-alkane is utilized as a proxy for paleohydrological reconstruction.

Terrestrial ecosystems generally contain various plant types (e.g. dicots, monocots, gymnosperms), and an evaluation of the dominant plant type in an ecosystem is the key to understanding geological records in paleoenvironmental research. In this study, we examined n-alkane chain length distributions in terrestrial higher plants in the central Chinese Loess Plateau, and found that average chain length (ACL) could be utilized as an indicator for differentiating gymnosperms from angiosperms. ACL21–33 was less than 27 for gymnosperms, but more than 27 for angiosperms. Moreover, a derived Pv index from a selected n-alkane ratio, (i.e. (C31 + C33)/ΣCn(n=27–33)), provided a relative criterion for distinguishing between dicots and monocots within the angiosperms. When Pv 0.1, were dominated by monocots. Discrimination of the dominant plant type in an ecosystem is important when leaf wax n-alkanes are used as a proxy for paleoenvironmental reconstructions.

This paper presents an analysis of the transient contact solutions of wheel-rail frictional rolling impacts calculated by an explicit finite element model of the wheel-insulated rail joint (IRJ) dynamic interaction. The ability of the model to simulate the dynamic behavior of an IRJ has been validated against a comprehensive field measurement in a recent paper (Yang et al., 2018). In addition to the measured railhead geometry and bi-linear elastoplastic material model used in Yang et al. (2018), this study adopts a nominal railhead geometry and an elastic material model for the simulations to provide an overall understanding of the transient contact behavior of wheel-IRJ impacts. Each simulation calculates the evolution of the contact patch area, stress magnitude and direction, micro-slip distribution, and railhead nodal vibration velocity in the vicinity of the joint during the wheel-IRJ impacts. The simulations apply small computational and output time steps to capture the high-frequency dynamic effects at the wheel-IRJ impact contact. Regular wave patterns that indicate wave generation, propagation and reflection are produced by the simulations; this has rarely been reported in previous research. The simulated waves reflect continuum vibrations excited by wheel-rail frictional rolling and indicate that the simulated impact contact solutions are reliable.

Optimisation of manufacturing process parameters requires resource-intensive search in a high-dimensional parameter space. In some cases, physics-based simulations can replace actual experiments. But they are computationally expensive to evaluate. Surrogate-based optimisation uses a simplified model to guide the search for optimised parameter combinations, where the surrogate model is iteratively improved with new observations. This work applies surrogate-based optimisation to a composite textile draping process. Numerical experiments are conducted with a Finite Element (FE) simulation model. The surrogate model, a deep artificial neural network, is trained to predict the shear angle of more than 24,000 textile elements. Predicting detailed process results instead of a single performance scalar improves the model quality, as more relevant data from every experiment can be used for training. For the textile draping case, the approach is shown to reduce the number of resource-intensive FE simulations required to find optimised parameter configurations. It also improves on the best-known overall solution.

Titanium alloys have become attractive candidates for structural materials in aviation industry, benefited from their reliable mechanical properties. In the present investigation, dual laser beam bilateral synchronous welding experiments of Ti6Al4V alloy under various welding speeds were performed using optic fiber laser. Experimental results indicate that the heat affect zone has become the weakest region of the joints theoretically. Inappropriate welding speed lead to a severe coarsening of the equiaxed grains below the lower fusion zone, which is the main reason why the tensile strength of the construction decreased significantly. Additionally, the ultimate tensile strength of the T-joint under the welding speed of 22 mm/s has reached 808 MPa, exceeding 90% of the strength of the base metal. According to the fractographs, the T-joints adopted higher welding speeds have failed in the form of microporous aggregation fracture. In contrast to the others, it can be concluded that the fracture mode of the T-joint under the lowest welding speed is a mixed fracture composed of cleavage fracture and ductile fracture.

The microstructure and microtexture evolution of Ti–6Al–4V T-joints produced by dual laser beam bilateral synchronous welding (DLBSW) were investigated using the optical microscopy (OM) and electron back-scattered diffraction (EBSD) and correlated with the mechanical properties of the joint. We demonstrate important differences in temperature field, grain morphology, misorientation angles and texture intensity between the base material (BM), the skin-side heat-affected zone (SK-HAZ), the stringer-side heat-affected zone (ST-HAZ) and the weld seam (WS). Through in-depth crystallographic analysis, we demonstrate that the kernel average misorientation curve of the WS is steeper and the peak misorientation angle is larger, revealing that the WS has a lower geometrically necessary dislocations density and a smaller residual strain. Due to the different orientation of each a-phase colony at the interface of the two phases, it is not conducive to the deformation mode of dislocation slip, so a large number of twins are generated in the WS. Furthermore, the WS has a strong crystal preferential orientation and the maximum polar density of the pole figure is 17.05, which is significantly higher than the polar density of the base material. It is found that the gradient of microstructure variation in the narrow HAZ is higher than that in the WS, which leads to more heterogeneous properties in the HAZ compared to the weld. This research result is consistent with the phenomenon that all the fractures of the resultant T-joints occurred in the HAZ.

Reconstructing paleoelevation allows the temporal evolution of biogeochemical processes and hydroclimate regimes to be understood and quantified. A dual-isotope biomarker of clumped hydrogen and carbon isotopes of leaf wax n-alkanes was recently proposed in humid tropical forests, and it was proven to be superior to a single-isotope proxy that was previously reported. However, it remains unknown whether the dual-isotope biomarker is suitable in arid conditions. The present study investigated leaf wax n-alkane distribution, hydrogen (δ2Hwax) and carbon (δ13Cwax) isotopes in terrestrial plants along an arid mountainous transect. We found that the effects of seasonality on n-alkane distribution, δ2Hwax and δ13Cwax were minimal for all species (p > 0.05), and that species-specific δ2Hwax values remained almost unchanged for most species, in contrast to δ13Cwax values. Significant correlations between altitude and δ2Hwax values (R2 = 0.54, 0.58, and 0.75 for spring, summer, and autumn, respectively), instead of δ13Cwax values (R2 = 0.08, 0.43, and 0.12 with p = 0.24, 0.01, and 0.19 for spring, summer, and autumn, respectively), were observed, suggesting that δ2Hwax values, but not δ13Cwax values, can be reliably used as a proxy for reconstructing paleoelevation in arid conditions. Therefore, it will be necessary to identify other proxies to supplement δ2Hwax values under a dual-isotope approach in future research.

Some studies have demonstrated that leaf wax δDn-alkane values for a single species varied significantly with seasons. However, it is still not clear that the seasonality patterns of leaf wax δDn-alkane values in higher plants. Meanwhile, few efforts have been pursued to assess the effect of the light slopes (sunny vs. cloudy) on leaf wax δDn-alkane values. In this study, we systematically investigated plant wax δDn-alkane values and soil n-alkane δD values along different light slopes in different seasons (spring vs. autumn), as well as the relationship of n-alkane δD values between plant leaves and soil. We found that plant wax δDn-alkane values were D-enriched by ca. 20‰ in spring relative to autumn, and ca. 10‰ in the sunny slope than in the cloudy slope. Moreover, surface soil n-alkane δD values varied consistently with plant wax δDn-alkane values for different seasons and light slopes. More importantly, plant wax δDn-alkane values showed clear seasonal variations, but varied slightly with light slopes. The variations of plant wax δDn-alkane values can be recorded in soil n-alkane δDn-alkane values. In addition, we found that leaf wax δDn-alkane values in a majority of species differed significantly among woods, non-woods and grasses at a site. Therefore, we suggested a good choice to sample at the site dominated by woods when leaf wax δDn-alkane values are utilized as a proxy for the reconstruction of the paleoenvironment.

Using a regulatory change on the IPO lockup for institutional investors and a unique disclosure of institutional investor bidding information in China, we examine the impact of IPO lockup removal on IPO pricing. We document that the IPO lockup removal increases institutional investor bid price. The effect is stronger for sub-samples with less reputable underwriter and IPOs with high value uncertainty. The impact is channeled to a higher IPO offer price and a lower first day return. These results suggest that IPO lockup removal (IPO lockup) increases (decreases) IPO share valuation.

Isotope mass balance models have been widely applied for assessing the water balance of closed and open lake systems in remote regions with sparse monitoring gauges. The role of evaporation in determining the water balance of Qinghai Lake has been unclear in recent decades, when the lake level has continued to rise. In the current study, stable water isotopes (δ 18 O and δ 2 H) from precipitation, river water, and lake water were investigated and used to model the evaporation:inflow (E/I) ratio of Qinghai Lake between 2013 and 2014. The results revealed that the relationship between δ 18 O and δ 2 H in lake water (δ 2 H = 4.58δ 18 O − 1.4, R 2 = 0.836) differed from that in precipitation (δ 2 H = 8.17δ 18 O + 16.2, R 2 = 0.967). The δ 18 O and δ 2 H values in lake water with low mean deuterium excess values (− 7.23‰ ± 0.34‰) were more positive than those in precipitation and river water, implying that lake water had experienced stronger isotopic enrichment. Quantitative analysis using an isotope mass balance model showed that mean E/I ranged from 0.57 to 1.04 in Qinghai Lake during the study period. The interannual variability of E/I was mainly related to the changes in inflow water and isotopic compositions in atmospheric vapor. The changes in E/I indicated that both inflow and runoff have dominated the water balance of Qinghai Lake in recent years, partly explaining the recent increase in water level in the lake and the resulting expansion in its surface area. These results facilitate a better understanding of the current and future status of the water balance of lakes on the Tibetan Plateau and regional hydrological processes based on limited instrumental observations.

A series of revegetation programs have been carried out since 1950s, and a large area of cropland has been converted to forestland and grassland through tree plantation and natural vegetation restoration. However, it is still inadequately addressed how plant revegetation changes the characteristics of soil-plant waters. In this study, we compared δ18O and δ2H values of different waters from precipitation, soil water, root water, and leaf water between different herbaceous plants (understory of the planted forestland and natural recovered grassland) in two neighboring catchments. There was a temporal consistence in δ18O and δ2H among different waters, showing that root water and leaf water could record well the signals of soil water and precipitation, followed by temperature change over month. A series of water line equations between δ18O and δ2H indicate that herbaceous plants have higher soil evaporation for grassland than understory of the forestland, instead of leaf transpiration. Moreover, our study found significant differences in δ18O and δ2H between root water and soil water, probably associated with isotopic fractionation during root water uptake, leaf surface water pools and ecohydrological separation. This study will be helpful to better understand the effect of plant revegetation programmes (planted forestland catchment versus natural grassland catchment) on ecohydrological processes on the Chinese Loess Plateau.

Interactions between the Yangtze River and Poyang Lake are undergoing rapid changes due to intensive human activities and ongoing climate change. This study investigates the spatiotemporal variations of isotopic compositions (δ2H and δ18O) in river and lake water to explore the river–lake interactions in combination with water level and discharge in Poyang Lake watershed. The results showed that river and lake water isotopes (δ2H and δ18O) exhibited highly temporal heterogeneity across seasons but their spatial differences were not remarkable, which is closely related with water sources from local precipitation and groundwater, and lake hydrology. The homogeneous patterns of lake water δ2H and δ18O indicated that Poyang Lake is a well-mixed lake in spatial scales. By contrast, the river (10.7‰) and lake (10.8‰) water d-excess and lc-excess (−0.6‰) were close to precipitation d-excess and lc-excess suggesting that precipitation is the main source for the lake and river. The slope and intercept of the river water line were slightly lower than those of the local meteoric water line and lake water line, which could be attributed to a greater evaporative enrichment in river water impacted by water flow regulation in the watershed. Interactions between Poyang Lake and Yangtze River vary seasonally, as evidently shown by the variations of water discharge and isotope compositions in river and lake water. The δ2H and δ18O of the Yangtze River water become more positive in the downstream zone than those in the upstream zone, indicating that the water from Poyang Lake has a great impact on downstream river water. This result can also be demonstrated by the efflux rate from the Poyang Lake to the Yangtze River, ranging from 17.9% to 67.9% across seasons except for the outlier rate in October resulted from the backflow of water from Yangtze River to the Poyang Lake. The complex lake–river interactions between Poyang Lake and Yangtze River mainly resulted from the regulation of Three Gorges Dam and water discharge from Poyang Lake watershed. These findings of the complex lake–river interactions will help to improve understanding of the hydrological processes and transport of pollutants and solutes around the confluence zone of the Yangtze River and Poyang Lake.

The coplanar double lap-joint is the weld type mainly used for the connection of skin and stringer. The welding deformation in the component will reduce fabrication accuracy and bearing capacity and the excessive welding deformation can even render the product unusable. In the present work, a thermal-elastic-plastic finite element model is developed to investigate the characteristics of welding deformation in the coplanar double lap-joint. The experiment is carried out to verify the accuracy of simulated results. The results of the simulation shows a good agreement with the experimental measurements. The influence of welding direction on welding deformation is studied by finite element analysis. Moreover the mechanism of deformation mode in the coplanar double lap-joint is discussed. The results show that the change of welding direction has different effects on the distribution of residual deformation. Through the analysis of simulation results, the deformation mode of the joint is similar to a concave-convex mode.

Studies focused on field measurements have been conducted to investigate how leaf wax n-alkane δ13C values vary among photosynthetic pathways (C3 vs. C4) or plant types (dicots, monocots, gymnosperms, magnoliids), and how n-alkane δ13C values respond to climate factors (precipitation, temperature). However, a systematic global analysis of plant n-alkane δ13C values with respect to major plant groups is still lacking, and the corresponding mechanism remains unknown. In this study, we compiled globally published n-alkanes δ13C data in modern plants. We find significantly negative correlations between δ13Cwt values and mean annual precipitation (MAP) for C3 plants (R2 = 0.30; p

Soil water plays a critical role in determining plant survival and growth globally, especially in water-limited regions. This study explores water-use characteristics of Robinia pseudoacacia during the transition period between the dry and rainy seasons in the Chinese Loess Plateau (CLP). A stable isotope technique (δ18O and δD) and two complementary approaches (i.e., the direct inference method and the MixSIAR model) were used to distinguish water source changes during this transition period. Based on δ18O and δD distribution patterns, we subdivided a 500 cm soil profile into four potential water sources: shallow (0–40 cm), intermediate-shallow (40–120 cm), intermediate (120–200 cm) and deep (200–500 cm). During the transition period, R. pseudoacacia exhibited different water uptake patterns. In April 26.2% and 48.4% of water uptake derived from the 40 to 120 and 200 to 500 cm soil profile layers; in May, 21.5%, 24.5% and 37.4% of water was absorbed from the 0 to 40, 40 to 120 and 200 to 500 cm soil profile layers. In June and July, 51.6% and 53.6% of the water mainly derived from the 0 to 120 cm soil profile layer, respectively. During the dry season (April), the trend in water uptake shifted to the deep soil layer, potentially a key period for the onset of soil desiccation in this soil layer. As precipitation increased, the proportion of water uptake from the shallow and intermediate-shallow soil layers increased. Because water-use pattern characteristics could provide important information on the development of the dried soil layer (DSL), the stable isotope technique could help reveal the water sources used by trees while also offering insight into water movement mechanisms of local ecosystems. Given its usefulness, the application of the stable isotope technique should be expanded in analyzing practical ecohydrological issues that occur in deep soils in the future.

Many studies have observed that leaf wax δDn-alkanes values differed significantly between woods and grasses in modern plants, with grasses D-depleted by 40 ‰–70 ‰. The reasons for the differences in leaf wax δDn-alkane values between woods and grasses, however, remain unclear. In this study, we measured the δD values of soil water (δDsw), leaf water (δDlw), and leaf wax n-alkane (δDn-alkane) for woods and grasses. We found no significant differences in the δD values of soil water (P = 0.82) and leaf water (P = 0.74) between the two life forms of plants. Therefore, the differences in leaf wax δDn-alkane values between woods and grasses may correlate with inherent properties of different plant life forms, such as leaf structures, biosynthetic processes, and leaf morphologies. Moreover, it is also possible that soil water with different δDsw at different depths utilized by woods and grasses may be responsible for some of the differences in leaf wax δDn-alkane values between the two life forms of plants, if woods mainly use soil water from the >100 cm depth, whereas grasses mainly use soil water from the

Sedimentary δDn-alkane values have been widely used as a valuable proxy for paleoenvironmental reconstruction. A number of studies have focused on δDn-alkane values that derived exclusively from leaves, while less attention has been paid to the root-derived n-alkanes and their impact on sedimentary δDn-alkane values. In this study, we sampled modern plant leaf and root materials from different growth contexts (slopes and seasons) on the Chinese Loess Plateau to compare leaf-derived n-alkanes with root-derived n-alkanes. Our results demonstrated that total n-alkane (C27–C33) concentrations varied substantially between leaf and root materials, with average values of 209 and 29.5 μg/g observed in leaves and roots respectively. The results suggest that ca. 12% of the n-alkane concentrations in sediments may be derived from plant roots. Furthermore, leaf-derived δDn-alkane values for Stipa bungeana (grass), Artemisisa vestita (shrub) and Bothriochloa ischaemum (grass) averaged −184‰, −152‰ and −198‰, compared with their root-derived δDn-alkane values of −199‰, −179‰ and −163‰, respectively. These statistically significant differences in concentrations and δD values between leaf-derived and root-derived n-alkanes suggest that the contribution of n-alkanes derived from plant roots is important for evaluating the resultant n-alkane compositions of sediments for paleoenvironmental reconstruction. Our findings indicates that the effects of root-derived n-alkanes on total sedimentary δDn-alkane values should be considered carefully in future paleoenvironmental reconstruction efforts.

This study examines the clustering and discounting of offer prices in auction-style seasoned equity offerings (SEOs) in China. More importantly, using a unique dataset of detailed bidding data submitted by participating investors in SEOs using the uniform-price auction mechanism, we document the clustering of bid prices at integers, and find that the clustering and discounting of integer bid prices drive the clustering and discounting of integer offer prices. Further, we find evidence that bid prices tend to cluster at integers for SEOs with higher uncertainty, and the larger bid discounts associated with integer bids can be explained by bid shading.

A reaction calorimeter CPA-122 was used to determine the heats of absorption of CO 2 in 5 wt% NH 3 (aq), 0.86 mol PZ and the blended solutions (1.5–3.1 mol) NH 3 /(0.43–0.86 mol) PZ at 40 °C, 60 °C and 80 °C. The heat of absorption of CO 2 in 5 wt% NH 3 (aq) at low CO 2 loadings ( 2 /mol-Am) was measured to be 74.8 kJ/mol CO 2 at 40 °C and 65.9 kJ/mol CO 2 at 80 °C, and found to decrease gradually in the high loading interval (>0.5 mol-CO 2 /mol-Am). The heat of absorption of CO 2 in 0.86 mol PZ solution was measured to be 73 kJ/mol CO 2 in the low CO 2 loading interval ( 2 /mol-Am), and found to decrease gradually in the high loading interval (>0.5 mol-CO 2 /mol-Am) at 40 °C and 60 °C. The heat of absorption of CO 2 in 3.1 mol NH 3 + 0.86 mol PZ solution demonstrated a high degree of consistency with that of CO 2 in 3.1 mol NH 3 (aq), which indicated that blending a small amount of PZ does not have a significant effect on the heat of absorption. The mechanism of the absorption process of CO 2 in the mixtures is also discussed in depth in this paper.

A small wetted wall column (WWC) was used to study the kinetics of CO 2 absorbed in PZ and NH 3 /PZ blended solution. The experiments of CO 2 absorption into 0.1–0.4 M PZ and 0.53–4 M NH 3 /0.1–0.4 M PZ mixed solution at 10–40 °C have been done in wetted wall column under the driving force of 8–25 kPa in this paper. The ‘interface concentration corrected-pseudo first order’ mass transfer model and ‘Ternary-termolecular’ reaction mechanism were proposed to describe the CO 2 absorption into NH 3 /PZ system for the high driving force and low PZ concentration condition. Both of the models in this study used for CO 2 with NH 3 /PZ blended solution were in a good agreement with the experimental results.

Volatility is an important issue for aqueous ammonia used as an absorbent for post-combustion CO2 capture. Vapor–liquid equilibrium (VLE) of NH3 in aqueous ammonia and aqueous blends of ammonia and piperazine (PZ) were measured at 20 °C, 30 °C and 40 °C. The experimental VLE results for NH3 cover the mole fraction ranges 2.5–15% NH3 (aq) in aqueous ammonia and 2.5–15% NH3 in the 0.4 M PZ blended solutions. Vapor pressures of NH3 for 5%, 10% and 15% NH3 (aq) were compared with available data in the literature. Activity coefficients for NH3 in NH3 (aq) and aqueous blends of NH3 + PZ were calculated and compared for different temperatures to obtain the effect of PZ on the volatility of aqueous ammonia. The eNRTL model was used to model the results and a comparison between model predictions and experimental data shows good agreement.