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Abstract Pelvic organ prolapse (POP) and urinary incontinence (UI) are common disorders that significantly impact women’s quality of life. Studies have demonstrated that cytokines, including pro- and anti-inflammatory immune mediators, play a role in illness genesis and progression. Research on the inflammatory milieu of the pelvic floor has shown that POP patients have increased inflammation in vaginal tissues. This evidence revealed that significant changes in the inflammatory milieu of the pelvic floor are an aspect of the pathogenesis of POP. POP patients exhibit increased levels of inflammatory cytokines (IL-1, TNF, IFN, and others) in the front vaginal wall, which may alter collagen metabolism and contribute to POP. Studies indicate that cytokines such as IL-6, IL-10, and TGF, which are involved in inflammation, remodelling, and repair, have dual effects on POP and UI. They can promote tissue healing and regeneration but also exacerbate inflammation and fibrosis, contributing to the progression of these conditions. Understanding the dual roles of these cytokines could help us improve the vaginal microenvironment of women and treat POP and UI. Given the considerable changes in these cytokines, this review addresses studies published between 2000 and 2024 on the molecular mechanisms by which pro- and anti-inflammatory cytokines affect women with POP and UI. Furthermore, we explain novel therapeutic strategies for cytokine regulation, emphasizing the possibility of personalized treatments that address the underlying inflammatory milieu of the vagina in POP and UI patients. This thorough analysis aims to establish a foundation for future research and clinical applications, ultimately improving patient outcomes via designed cytokine-based therapies.

Abstract Oceanic submesoscale processes are ubiquitous in the North Pacific Subtropical Gyre (NPSG), where the biological carbon pump is generally ineffective. Due to difficulties in collecting continuous observations, however, it remains uncertain whether episodic submesoscale processes can drive significant changes in particulate organic carbon (POC) export into the mesopelagic ocean. Here we present observations from high-frequency Biogeochemical-Argo floats in the NPSG, which captured the enhanced POC export fluxes during the intensifying stages of a submesoscale front and a cyclonic eddy compared to their other life stages. A higher percentage of POC export flux was found to be transferred to the base of mesopelagic layer at the front compared to that at the intensifying eddy and the mean of previous studies (37% vs. ~10%), suggesting that the POC export efficiency was significantly strengthened by submesoscale dynamics. Such findings highlight the importance of submesoscale fronts for carbon export and sequestration in subtropical gyres.

Diaphragm couplings are prone to developing diaphragm cracks under prolonged high-speed operating conditions, which can lead to degradation in the performance of the transmission system and affect the dynamics of the shafting system. To investigate the effects of diaphragm cracks on the dynamics of couplings and the shafting system, a finite element model of a diaphragm coupling with a crack failure is established using ANSYS finite element software to analyze the time-varying characteristics of the diaphragm coupling’s angular and radial stiffness. A shaft dynamics model of the diaphragm coupling with a crack is developed using Timoshenko beam elements to analyze the impact of different crack lengths and locations on the dynamics of the shafting system. The validity of the dynamic model for a diaphragm coupling with a crack is verified through a constant speed experiment conducted on a rotor test bench. The results indicate that diaphragm crack failure causes a change in the periodicity of the time-varying stiffness of the diaphragm coupling, leading to a distinct 2× component appearing in the frequency domain of the transmission shaft system.

The AT-hook motif nuclear localized (AHL) gene family is a highly conserved transcription factors involved in plant growth, development, and stress responses. However, AHLs have not been systematically analyzed in radish (Raphanus sativus). Therefore, we performed genome-wide identification and expression pattern, gene structure, and function verifications of radish AHLs. We identified 52 radish AHLs (RsAHL1–RsAHL52), which were unevenly distributed across nine chromosomes. Phylogenetic analysis showed that the RsAHLs were divided into two clades (A and B) and subdivided into three types (I, II, and III). Collinearity analysis revealed that the 52 RsAHLs produced 49 repeat events. Tissue expression profiles revealed differential expression of RsAHLs across different tissues, with higher expression observed in flower organs, particularly petals and anthers. qRT-PCR results indicated that RsAHLs responded to abscisic acid, methyl jasmonate, and abiotic stress (low and high temperatures and drought). Additionally, RsAHL14 induced a dwarf phenotype in tomato plants, and RsAHL14-overexpression tomato plants presented significantly decreased expression levels of the gibberellin (GA) synthetic genes ent-Copalyl diphosphatase, GA3ox-3/-4/-5, and GA20ox-1/-2/-3, but significantly increased expression of the degradation gene GA2ox-1/-3. Thus, RsAHL14 might affect plant growth by regulating GA content. Collectively, our study comprehensively identified RsAHLs in radish and provided a reference for further research on these genes.

BackgroundWork-related musculoskeletal disorders (WMSDs) seriously affect work efficiency and quality of life of nurses. Currently, there are significant differences in the published studies on WMSDs in nurses. ObjectiveTo systematically evaluate the prevalence of WMSDs among nurses in the mainland of China and analyze its main influencing factors. MethodsEight databases (CNKI, Wanfang data, VIP, SinoMed, PubMed, Cochrane Library, Web of Science, and Embase) were selected for searching literature reporting prevalence and influencing factors of WMSDs among clinical nurses in China from inception to December 31, 2022. The literature was included according to a pre-set criteria of inclusion and exclusion. The quality of cross-sectional studies was assessed using the criteria recommended by the Agency for Healthcare Research and Quality (AHRQ), and the extracted data were analyzed by Stata 15.0 software. A random effect model or a fixed effect model was selected to calculate combined effects based on heterogeneity of included studies. ResultsA total of 19 studies were included in this meta-analysis, including 14 studies published in Chinese and 5 in English, involving 17852 nurses in total. The estimated prevalence rate of WMSDs since work among clinical nurses in China was 85.5% (95%CI: 79.8%, 91.1%), the estimated annual prevalence rate was 81.0% (95%CI: 75.2%, 86.8%), and the estimated weekly prevalence rate was 65.0% (95%CI: 48.5%, 81.5%). The results of subgroup analysis showed that the prevalence rate of WMSDs among nurses in specific departments of emergency, ICU, and midwifery was 88.6% (95%CI: 82.6%, 94.6%), higher than that among nurses in general departments [79.0% (95%CI: 72.5%, 85.5%)]. The reported prevalence of WMSDs from 2018 to 2022 was 82.2% (95%CI: 75.0%, 89.4%), which was higher than that from 2004 to 2017 [76.8% (95%CI: 67.2%, 86.4%)]. Age >40 years (OR=2.34, 95%CI: 1.69, 3.24), length of service >10 years (OR=2.12, 95%CI: 1.43, 3.15), obesity (OR=2.73, 95%CI: 1.56, 4.77), night shift (OR=2.03, 95%CI: 1.81, 2.28), lifting heavy objects (OR=3.80, 95%CI: 1.79, 8.07), rest during work (OR=0.49, 95%CI: 0.30, 0.83), and bending (OR=3.47, 95%CI: 2.37, 5.08) were influencing factors of WMSDs in nurses. ConclusionThe prevalence rate of WMSDs among Chinese nurses is high, and it is increasing year by year. Nurses in specific departments such as emergency, ICU, and midwifery show higher prevalence rates than those in general departments. Age > 40 years, length of service >10 years, obesity, night shifts, lifting heavy objects, and bending are risk factors for WMSDs among nurses, while rest during work is a protective factor. Therefore, early prevention actions should be taken targeting the above factors, such as increasing auxiliary assistance facilities and improving work patterns, so as to reduce the risk of WMSDs.

Two problems exist in the study of the trajectory optimization problem of powered hypersonic gliding vehicles (HGVs) due to insufficient consideration of the overall design constraints as well as the strong couplings among relevant disciplines: (1) the engine and thrust models are not compatible with the existing HGV; (2) configuration parameters of the HGV are not included as design variables during trajectory optimization (i.e., propulsion discipline is decoupled in the process of the HGV configuration design), thus failing to fully explore the effect of power to improve the performance of the HGV. Therefore, the application of multidisciplinary design optimization (MDO) in the overall design of powered HGVs should be investigated. First, a MDO task analysis and a multidisciplinary model analysis are carried out for the powered HGV. Second, the multidisciplinary optimization problem is defined, and the couplings between disciplines of the powered HGV are analyzed so that a six-discipline model is established that is suitable for the overall design process, including the parameterized configuration geometry, aerodynamics, propulsion, mass properties, trajectory, and aerodynamic heat/thermal protection system (TPS). Finally, a surrogate model is used to replace the time-consuming accurate model, and numerical optimization examples verify the effectiveness of the method. The optimization results show that the method has a good convergence speed, which increases the gliding range of the optimized vehicle by 8.37%. In addition, by decoupling the propulsion discipline, the validation shows that the coupled propulsion discipline during the overall design can increase the range of the powered HGV by 3.87% compared to the powered HGV optimized with the decoupled propulsion discipline. The work done in this paper provides a new design idea for the overall design of a powered HGV.

Continental marginal seas are key systems in the global carbon cycle. Carbon stocks represent the ability to store carbon, thus quantifying the carbon stocks in marine sediments would help to better understand their importance in the carbon cycle. In this study, 17 sediment cores in the mud areas of the South Yellow Sea and the East China Sea were measured for total organic carbon (TOC) and its stable isotope (δ13C), and dry bulk density; and from which the carbon stocks and carbon stock accumulation rate as well as marine/terrestrial carbon stocks/carbon stock accumulation rate were calculated. The carbon stocks in the mud area of the South Yellow Sea showed a decreasing trend during 1855 to 1950 caused by the relocation of the Yellow River Estuary in 1855, but increased after 1950s due to increased sediment input via the enhancement of South Shandong Coastal Current. In the Min-Zhe belt of the East China Sea, carbon stocks showed an overall high marine proportion due to the phytoplankton bloom induced by high nutrient level, but the decreased carbon stocks in recent decades were mainly caused by the construction of reservoirs in the Yangtze River that reduced sediment transports. The average carbon stocks in 1 m sediments from the South Yellow Sea (45.2 t ha-1) and Min-Zhe belt (52.8 t ha-1) were low compared to that of global marine sediments (66.6 t ha-1), while the carbon stock accumulation rate showed much higher values (0.1 t ha-1 yr-1 in South Yellow Sea and 0.31 t ha-1 yr-1 in the Min-Zhe belt) because of higher sedimentation rates. Although carbon stocks of Chinese marginal seas were also lower than that of the tidal flats (70.7 t ha-1) and wetland (123.6 t ha-1) in China, their much larger area could store 0.75 Pg C in marine sediments. Our temporal records suggest that anthropogenic activities have reduced carbon stocks in the marginal seas since 1950, causing carbon to re-enter the atmosphere to impact climate changes.

The issue of hypersonic boundary layer transition prediction is a critical aerodynamic concern that must be addressed during the aerodynamic design process of high-speed vehicles. In this context, we propose an advanced mesoscopic method that couples the gas kinetic scheme (GKS) with the Langtry–Menter transition model, including its three high-speed modification methods, tailored for accurate predictions of high-speed transition flows. The new method incorporates the turbulent kinetic energy term into the Maxwellian velocity distribution function, and it couples the effects of high-speed modifications on turbulent kinetic energy within the computational framework of the GKS solver. This integration elevates both the transition model and its high-speed enhancements to the mesoscopic level, enhancing the method’s predictive capability. The GKS-coupled mesoscopic method is validated through a series of test cases, including supersonic flat plate simulation, multiple hypersonic cone cases, the Hypersonic International Flight Research Experimentation (HIFiRE)-1 flight test, and the HIFiRE-5 case. The computational results obtained from these cases exhibit favorable agreement with experimental data. In comparison with the conventional Godunov method, the new approach encompasses a broader range of physical mechanisms, yielding computational results that closely align with the true physical phenomena and marking a notable elevation in computational fidelity and accuracy. This innovative method potentially satisfies the compelling demand for developing a precise and rapid method for predicting hypersonic boundary layer transition, which can be readily used in engineering applications.

Planetary reducer box undertakes the vibration transmitted from gear transmission system to bearing, and further transmits the vibration to the base. Research on the transmission path contribution of reducer box has an important guiding role in reducing vibration. This paper first analyzed the contribution of each vibration path of the gearbox based on the velocity intervention loss, so as to identify the main transmission path of the gearbox vibration; then the vibration test of the gearbox is carried out to verify the correctness of the transmission path model. The results show that the vibration transmission path of the right bearing of the gearbox is the main transmission path, and the established vibration transmission path dynamics model of the gearbox can well reveal the contribution law of the vibration transmission path of the gearbox.

Abstract To overcome the defects of traditional rarefied numerical methods such as the Direct Simulation Monte Carlo (DSMC) method and unified Boltzmann equation schemes and extend the covering range of macroscopic equations in high Knudsen number flows, data-driven nonlinear constitutive relations (DNCR) are proposed first through the machine learning method. Based on the training data from both Navier-Stokes (NS) solver and unified gas kinetic scheme (UGKS) solver, the map between responses of stress tensors and heat flux and feature vectors is established after the training phase. Through the obtained off-line training model, new test cases excluded from training data set could be predicated rapidly and accurately by solving conventional equations with modified stress tensor and heat flux. Finally, conventional one-dimensional shock wave cases and two-dimensional hypersonic flows around a blunt circular cylinder are presented to assess the capability of the developed method through various comparisons between DNCR, NS, UGKS, DSMC and experimental results. The improvement of the predictive capability of the coarse-graining model could make the DNCR method to be an effective tool in the rarefied gas community, especially for hypersonic engineering applications.

Abstract Background Ascorbic acid (Vitamin C, AsA) is an antioxidant metabolite involved in plant development and environmental stimuli. AsA biosynthesis has been well studied in plants, and MIOX is a critical enzyme in plants AsA biosynthesis pathway. However, Myo-inositol oxygenase (MIOX) gene family members and their involvement in AsA biosynthesis and response to abiotic stress remain unclear. Results In this study, five tomato genes encoding MIOX proteins and possessing MIOX motifs were identified. Structural analysis and distribution mapping showed that 5 MIOX genes contain different intron/exon patterns and unevenly distributed among four chromosomes. Besides, expression analyses indicated the remarkable expression of SlMIOX genes in different plant tissues. Furthermore, transgenic lines were obtained by over-expression of the MIOX4 gene in tomato. The overexpression lines showed a significant increase in total ascorbate in leaves and red fruits compared to control. Expression analysis revealed that increased accumulation of AsA in MIOX4 overexpression lines is possible as a consequence of the multiple genes involved in AsA biosynthesis. Myo inositol (MI) feeding in leaf and fruit implied that the Myo-inositol pathway improved the AsA biosynthesis in leaves and fruits. MIOX4 overexpression lines exhibited a better light response, abiotic stress tolerance, and AsA biosynthesis capacity. Conclusions These results showed that MIOX4 transgenic lines contribute to AsA biosynthesis, evident as better light response and improved oxidative stress tolerance. This study provides the first comprehensive analysis of the MIOX gene family and their involvement in ascorbate biosynthesis in tomato.

The helicopter tail drive shaft system is a typical multi-point supported drive shaft system, with a long span that can lead to serious vibration problems. Shaft vibration can be effectively reduced by installing a rubber-silicone oil combined damper between the bearing and bearing pedestal at the support point along the tail drive shaft. Stiffness and damping characteristics of the rubber-silicone oil combined damper are important factors affecting shaft vibration. In this study, the effects of silicone oil on the stiffness and damping of rubber-silicone oil combined damper were analyzed through simulations. The simulation method was experimentally verified and factors influencing the static stiffness, dynamic stiffness, and damping characteristics of the damper were investigated. In addition, the influence of damper dimensions and external excitation frequency on the stiffness and loss factor of the damping ring in the presence and absence of silicone oil were examined. The presence of silicone oil increases the difference between the dynamic stiffness and the loss factor. As the viscosity of the silicone oil increases, the static stiffness, dynamic stiffness, and loss factor of rubber-silicone oil combined dampers increase. The results have important guiding significance in the design of dampers for shafting systems.

The Huanghe (Yellow River) supplies large amount of sediments and terrestrial organic carbon (OC) to the eastern Chinese marginal seas. A relocation of the Huanghe outlet from the southern Yellow Sea (YS) to the Bohai Sea occurred in 1855 AD, however, detailed knowledge about the impact of this relocation on sedimentary source and OC burial in Chinese marginal seas is still critically lacking. In this study, we present total OC content and its isotope (δ13C), along with bulk total organic carbon (TOC)/total nitrogen (TN) molar ratio and lipid biomarker contents, in a sediment core HH12 from the southern YS with sediment age spanning the last 300 years. We find that TOC and terrestrial lipid biomarker mass accumulation rates were lower between 1855 AD and 1950 AD than that prior to 1855 AD in core HH12; and in accordance, both TOC/TN ratio and δ13C records indicate a gradual decrease of terrigenous source contributions to sedimentary OC. This suggests that the relocation of the Huanghe outlet reduced the transport of terrestrial OC to the southern YS. However, the δ13C record also indicates a relative increase of terrestrial OC contribution to sedimentary OC after 1950 AD, and the most likely explanation is increased contributions from the old Huanghe delta erosion and Korean rivers. Future studies should focus on better constraining the variations of terrestrial and marine endmembers with δ13C and Δ14C analyses of specific biomarkers to examine these linkages.

At present, the thermal analysis of oil-air-lubricated angular-contact ball bearings uses empirical heat transfer coefficients to calculate heat transfer. This approach presents problems such as simulating the actual lubrication flow field and ignoring the internal heat conduction in the bearing ring. This paper proposes a CFD steady-state analysis model of oil-air-lubricated angular-contact ball bearings based on fluid-solid conjugate heat transfer to analyze the flow field and temperature field. A temperature rise test of oil-air-lubricated angular-contact ball bearings was carried out to verify the positive determination of the simulation analysis results. Based on a fluid-solid conjugate heat transfer steady-state analysis model, the effects of lubrication parameters, operating conditions, and rolling element materials on the temperature rise characteristics of oil-air-lubricated angular-contact ball bearings were studied. The research results provide a method for analyzing the temperature rise characteristics of oil-lubricated bearings and provide a basis for the analysis of oil-lubricated bearing life.

The rotational energy of diatomic gases would be activated by the process of intermolecular collisions in high-temperature hypersonic flows. In this paper, a multi-temperature nonlinear coupled constitutive model has been proposed for simulating the transfer of energy between translational and rotational motions in hypersonic non-equilibrium flows. In this model, the nonlinear coupled constitutive equations are modified by introducing a rotational energy relaxation model and a changeable viscosity ratio related to local temperature. To confirm its accuracy, the new model is applied to investigate steady shock wave structures and high-speed gas flows around a cylinder and across a flat plate. The computational results are compared with the multi-temperature Navier–Stokes (NS) equations, the direct simulation Monte Carlo (DSMC) solutions, and the experiment data. The final results show the new model would reproduce the NS results at low Knudsen numbers but behave quite differently from the NS results as the non-equilibrium degree is enhanced. The new model is in better agreement with the DSMC solutions and the experimental data than the NS solutions in the far-from-equilibrium regions, which demonstrates the potential of the new relaxation model in the simulation of hypersonic non-equilibrium flows.

Garcinia oblongifolia Champ. ex Benth is rich in bioactive molecules with immense remedial qualities and has pharmaceutical potentials. In this study, we reported the complete chloroplast genome (cpDNA) of G. oblongifolia, which is 156,577 bp in length, including a large single copy region (LSC) of 85,393 bp, a small single copy region (SSC) of 17,064 bp, and a pair of inverted repeats (IR) regions of 27,060 bp inserted between LSC and SSC. 129 genes are encoded, including 83 protein-encoding genes, 8 ribosomal RNA genes, and 36 transfer RNA genes. The overall GC content of the chloroplast genome is 36.2%, wherein the corresponding values in the LSC, SSC and IR regions are 33.6%, 30.3%, and 42.2%, respectively. Phylogenetic analysis showed that G. oblongifolia is sister to G. gummi-gutta with strong bootstrap support.

Tomato (Solanum lycopersicum) is one of the highest-value vegetable crops worldwide. Understanding the genetic regulation of primary metabolite levels can inform efforts aimed toward improving the nutrition of commercial tomato cultivars, while maintaining key traits such as yield and stress tolerance. We identified 388 suggestive association loci (including 126 significant loci) for 92 metabolic traits including nutrition and flavor-related loci by genome-wide association study from 302 accessions in two different environments. Among them, an ascorbate quantitative trait locus TFA9 (TOMATO FRUIT ASCORBATEON CHROMOSOME 9) co-localized with SlbHLH59, which promotes high ascorbate accumulation by directly binding to the promoter of structural genes involved in the D-mannose/L-galactose pathway. The causal mutation of TFA9 is an 8-bp InDel, named InDel_8, located in the promoter region of SlbHLH59 and spanned a 5'UTR Py-rich stretch motif affecting its expression. Phylogenetic analysis revealed that differentially expressed SlbHLH59 alleles were selected during tomato domestication. Our results provide a dramatic illustration of how ascorbate biosynthesis can be regulated and was selected during the domestication of tomato. Furthermore, the findings provide novel genetic insights into natural variation of metabolites in tomato fruit, and will promote efficient utilization of metabolite traits in tomato improvement.

A proper hardening depth is critical to the load-bearing capacity of a part, and heat treatment, including carburizing and quenching, can highly determine the hardness distribution in the part’s surface after manufacturing. This paper proposes a ‘hardness prediction and parameter optimization’ approach that deploys the finite element method (FEM), the artificial neural network (ANN), and the Genetic Algorithm (GA), to describe the relationships between the carburizing/quenching parameters and the hardening depths and conversely to determine the optimized parameters for a given hardening depth. First, the numerical models for carburizing, quenching, and the hardness field are built respectively. And based on these models, the finite element simulation model is designed to predict the carbon content, the microstructure and the hardness of the part. A BP network is then trained by using the data obtained from the finite element simulation, and the model between the carburizing/quenching parameters and the hardening depths on part is established. The optimization model for the carburizing/quenching parameters is finally established through GA, which can determine the optimized parameters for a given hardening depth. The effectiveness of the ‘prediction-optimization’ approach is verified by a series of experiments. The hardening depth predicted by the proposed approach holds a 10% relative error from that measured in the carburizing and quenching experiment. And the optimized parameters for the heat treatment process can work as a meaningful reference for the heat treatment.

This paper describes an experimental study of the cooling capabilities of microchannel and micro-pin-fin based on-chip cooling systems. The on-chip cooling systems integrated with a micro heat sink, simulated power IC (integrated circuit) and temperature sensors are fabricated by micromachining and silicon-to-silicon direct bonding. Three micro heat sink structures: a microchannel heat sink (MCHS), an inline micro-pin-fin heat sink (I-MPFHS) and a staggered micro-pin-fin heat sink (S-MPFHS) are tested in the Reynolds number range of 79.2 to 882.3. The results show that S-MPFHS is preferred if the water pump can provide enough pressure drop. However, S-MPFHS has the worst performance when the rated pressure drop of the pump is lower than 1.5 kPa because the endwall effect under a low Reynolds number suppresses the disturbance generated by the staggered micro pin fins but S-MPFHS is still preferred when the rated pressure drop of the pump is in the range of 1.5 to 20 kPa. When the rated pressure drop of the pump is higher than 20 kPa, I-MPFHS will be the best choice because of high heat transfer enhancement and low pressure drop price brought by the unsteady vortex street.

In order to improve the machining accuracy of a gantry machining center, structural bionic design for column was conducted. Firstly, the bionic design method for stiffener plate structure was established based on distribution principles of gingko root system. The bionic design method was used to improve column structure of the gantry machining center, and three kinds of bionic columns were put forward. The finite element analysis on original and bionic columns indicates that the mass of the column with the best bionic stiffener plate structure is reduced by 2.74% and the first five order natural frequencies are increased by 6.62% on average. The correctness of column's bionic design method proposed in this paper was verified by the static and dynamic experiments. Finally, the bionic principles for stiffener plate of column were concluded, which provides a new idea for updating traditional design concepts and achieving lightweight structure of machine tool components.

A new method for calibrating a parallel robot is proposed as part of a project aimed at developing a calibration method for spacecraft docking mechanism motion simulator. To implement this method, a calibration equation is built by generating the constraint conditions of the end-effector's motion in the workspace using a three-dimensional coordinate measuring machine. According to the established calibration equation and the simulation, the geometrical parameters of the parallel robot are identified. The effectiveness of the calibration method with a coordinate measuring machine is verified through random pose test experiment.

This research aimed to characterize the physical and chemical properties of municipal solid waste (MSW) incineration fly ash, as well as to investigate the leaching of heavy metals during toxicity characteristics leaching procedure (TCLP) process. To understand the leaching behaviour, concentrations of heavy metals, chloride, sulphate and calcium at various leaching, time was monitored together with pH of the leaching solution. Results showed that the chemical compositions of fly ashes led to differences in leaching environment. For the two fly ashes under study, one resulted in a leaching environment with pH of 10-12 while the other had pH about 6-7. Based on pH, anions and cations concentrations, Minteq software was employed to investigate the speciation of heavy metals. Results showed that the shift in precipitation/dissolution balance of carbonate and hydroxides of heavy metals could explain the fluctuation in metal concentrations during the leaching process, which indicates that leaching was probably controlled by these reactions. On the other hand, addition of EDTA changed the controlling reactions. Chelating reactions between heavy metals and EDTA led to much higher leaching toxicity due to the presence of heavy metals, showing that the presence of chelating organics in natural environment may facilitate heavy metal leaching. [ABSTRACT FROM AUTHOR]

We conducted high vertical resolution samplings of total and particulate 234Th along with particulate organic carbon (POC) in the summer of 2017 to examine nutrient-dependent structures of export productivity within the euphotic zone (Ez) of the oligotrophic basin of the South China Sea (SCS). Nitrate concentrations throughout the study area were below detection limit in the nutrient-depleted layer (NDL) above the nutricline, while they sharply increased with depth in the nutrient-replete layer (NRL) across the nutricline until the base of the Ez. Based on our high resolution vertical profilings of 234Th/238U disequilibria, this study for the first time estimated POC export fluxes both out of the NDL and at the horizon of the Ez base. Total 234Th deficit relative to 238U occurred in the NDL at all study sites, while 234Th was mostly in equilibrium with 238U in the NRL except at the northmost station SEATS (116o E, 18o N), where the 234Th deficit could also be observed in the NRL. By combining 1D steady-state 234Th fluxes and POC/234Th ratios, we derived vertical patterns of POC export fluxes. Values were 1.6±0.6 mmol C m-2 d-1 at the NDL base, representing approximately half of the flux estimated at the base of the Ez at station SEATS; for the rest of the sampling sites, POC export fluxes at the NDL base (averaged at 2.3±1.1 mmol C m-2 d-1) were identical within error to those at the base of the Ez (1.9±0.5 mmol C m-2 d-1), suggesting rapid export of POC out of the NDL. This finding fundamentally changes our traditional view that the NDL, being depleted in nutrients, would not be a net exporter of POC. Based on the positive relationship between POC export fluxes at the NDL base and supply potential of subsurface nutrients (i.e., nutricline depth and nutrient concentrations), we found that POC export fluxes (averaged at 3.4±1.2 mmol C m-2 d-1) at the NDL base at stations with shallow nutriclines and high subsurface nutrient concentrations were ~100% higher than the fluxes (averaged at 1.6±0.5 mmol C m-2 d-1) at other stations. We used a two-endmember mixing model based on the mass and 15N-isotopic balances to further evaluate the potential sources of new nitrogen that could support the observed particle export at stations SEATS and SS1, located respectively in the northern and southern basin of the SCS with different hydrological features. We showed that more than 50% of the particle flux out of the NDL was supported by nitrate sources other than atmospheric deposition and nitrogen fixation: likely supply from depth associated with episodic intrusions. However, the exact mechanisms and pathways for subsurface nutrients to support the export production from the NDL merit careful and dedicated studies. [ABSTRACT FROM AUTHOR]

This paper describes the computations of hypersonic flows in a diatomic gas in rotational nonequilibrium using a newly developed simplified set of Burnett equations designated as simplified conventional Burnett equations. Since the original formulation by Burnett, a number of variations to the original Burnett equations have been proposed, and the differences among these variants and their merits/shortcomings have been described in the literature. A new variant is created based on the conventional Burnett equations for hypersonic flows by neglecting higher-order terms that are inversely proportional to the Mach number. This set of simplified conventional Burnett equations is linearly stable for small disturbances in contrast to the conventional Burnett equations that suffer from Bobylev instability. To simulate the rotational nonequilibrium effect in a diatomic gas, both the Navier-Stokes and the simplified conventional Burnett equations are modified by including a rotational nonequilibrium relaxation model. The flow variables (density and translational and rotational temperature) for one-dimensional shock structure, flow past a twodimensional cylinder, and an axisymmetric bicone in nitrogen are computed using both the simplified conventional Burnett and Navier-Stokes equations in the continuum-transition regime and are compared with the direct simulation Monte Carlo results. Simplified conventional Burnett calculations are in close agreement with the direct simulation Monte Carlo results at high Mach numbers. [ABSTRACT FROM AUTHOR]

Because of errors in the kinematic parameters of parallel robots, it is necessary to identify them to improve the pose accuracy for accurate task performance of semi-physical simulation platform. In this paper, a methodical way of kinematic parameter identification is introduced. It requires measurements of all legs and the pose information provided by a coordinate measuring machine. Nonlinear least squares algorithm is employed to determine the kinematic parameters. The measurement errors in the leg sensors are considered during kinematic modeling and kinematic parameter identification. Simulations and experimental studies on a Stewart parallel robot built in the Institute of Electro-hydraulic Servo Simulation & Test System of Harbin Institute of Technology reveal the convenience and effectiveness of the proposed robot parameter identification algorithm and calibration method for parallel robots. [ABSTRACT FROM AUTHOR]

Workpiece deformation must be controlled in the numerical control machining process. Fixture layout and clamping force are two main aspects that influence the degree and distribution of machining deformation. In this paper, a multi-objective model was established to reduce the degree of deformation and to increase the distributing uniformity of deformation. The finite element method was employed to analyze the deformation. A genetic algorithm was developed to solve the optimization model. Finally, an example illustrated that a satisfactory result was obtained, which is far superior to the experiential one. The multi-objective model can reduce the machining deformation effectively and improve the distribution condition. [ABSTRACT FROM AUTHOR]

This research focused on removing arsenic (As) from groundwater by coupling iron-tailored activated carbon with iron solubilization. This was achieved by solubilizing iron grains that were interspersed within the tailored activated carbon. A commercially available bituminous coal carbon was preloaded with iron by an evaporation method. With natural groundwater as the source, the media processed 25,000 bed volumes (BV) of water before >10 µg/L As breakthrough occurred. In comparison, when 30% zero-valent iron (NI) grains were interspersed with iron-preloaded bituminous coal carbon, As breakthrough > 10 µg/L occurred at 45,000 BV. The As breakthrough corresponded to when most of the NI source had become visibly corroded. Although some solubilized iron escaped through the granular activated carbon media, this iron could be captured in a subsequent sand or activated carbon filter in order to yield water that would meet both primary and secondary drinking water standards. Field-scale tests are required to determine whether results at large scale corroborate the laboratory findings. [ABSTRACT FROM AUTHOR]

Abstract  We utilized 234Th, a naturally occurring radionuclide, to quantify the particulate organic carbon (POC) export rates in the northern South China Sea (SCS) based on data collected in July 2000 (summer), May 2001 (spring) and November 2002 (autumn). Th-234 deficit was enhanced with depth in the euphotic zone, reaching a subsurface maximum at the Chl-a maximum in most cases, as commonly observed in many oceanic regimes. Th-234 was in general in equilibrium with 238U at a depth of ∼100 m, the bottom of the euphotic zone. In this study the 234Th deficit appeared to be less significant in November than in July and May. A surface excess of 234Th relative to 238U was found in the summer over the shelf of the northern SCS, most likely due to the accumulation of suspended particles entrapped by a salinity front. Comparison of the 234Th fluxes from the upper 10 m water column between 2-D and traditional 1-D models revealed agreement within the errors of estimation, suggesting the applicability of the 1-D model to this particular shelf region. 1-D model-based 234Th fluxes were converted to POC export rates using the ratios of bottle POC to 234Th. The values ranged from 5.3 to 26.6 mmol C m−2d−1 and were slightly higher than those in the southern SCS and other oligotrophic areas. POC export overall showed larger values in spring and summer than in autumn, the seasonality of which was, however, not significant. The highest POC export rate (26.6 mmol C m−2d−1) appeared at the shelf break in spring (May), when Chl-a increased and the community structure changed from pico-phytoplankton (µm) dominated to nano-phytoplankton (2–20 µm) and micro-phytoplankton (20–200 µm) dominated. [ABSTRACT FROM AUTHOR]

Arsenic is of concern in water treatment because of its health effects. This research focused on incorporating hydrous ferric oxide (HFO) into granular activated carbon (GAC) for the purpose of arsenic removal. Iron was incorporated into GAC via incipient wetness impregnation and cured at temperatures ranging from 60 to 90 °C. X-ray diffractions and arsenic sorption as a function of pH were conducted to investigate the effect of temperature on final iron oxide (hydroxide) and their arsenic removal capabilities. Results revealed that when curing at 60 °C, the procedure successfully created HFO in the pores of GAC, whereas at temperatures of 80 and 90 °C, the impregnated iron oxide manifested a more crystalline form. In the column tests using synthetic water, the HFO-loaded GAC prepared at 60 °C also showed higher sorption capacities than media cured at higher temperatures. These results indicated that the adsorption capacity for arsenic was closely related to the form of iron (hydr)oxide for a given iron content. For the column test using a natural groundwater, HFO-loaded GAC (Fe, 11.7%) showed an arsenic sorption capacity of 26mg As/g when the influent contained 300 μg/L As. Thus, the preloading of HFO into a stable GAC media offered the opportunity to employ fixed carbon bed reactors in water treatment plants or point-of-use filters for arsenic removal. [ABSTRACT FROM AUTHOR]

Abstract Background There are few data available on the prevalence, incidence, and residual risk of transfusion-transmitted HBV (TT-HBV) infections among Chinese blood donors. This study investigated the demographic characteristics of blood donors, as well as the prevalence, incidence, and residual risk (RR) of TT-HBV infections in six large blood centers in different regions of China. Methods The demographic characteristics and HBV screening test results of blood donors from six blood centers in different regions in China were collected and analyzed. The hepatitis B surface antigen (HBsAg) yield approach was used to estimate the incidence of HBV. Then, the RR of TT-HBV infections was evaluated using the incidence-window period model. Results The majority of donors were between 18 and 35 years old (including 35), with the exception of the Changzhi Blood Center where a majority of donors were between 35 and 55 years old (including 55). The prevalences of HBV were 0.13%, 0.078%, 0.16%, 0.07%, 0.20%, 0.25% in Hefei, Dalian, Changzhi, Kaifeng, Mianyang and Fujian, respectively. The estimated corresponding incidences were 213.44, 161.59, 989.80, 278.05, 125.31 and 352.19 per 105 person-years. Using an infectious window period of 59 days, the RR for HBV was estimated to be 34.14, 25.85, 158.35, 44.48, 20.04 and 56.35 per 105 person-years in Hefei, Dalian, Changzhi, Kaifeng, Mianyang and Fujian, respectively. Conclusion Despite the introduction of more sensitive assays in blood screening, our data revealed that the current residual risk of TT-HBV infection was still high (overall 56.53 per 105 py). A continuous monitoring of the residual risk of transfusion-transmitted infections is crucial for safe blood management.

Due to the various requirements of users and large volume of machine tools, most machine tool manufacturers are adopting the small-lot production mode, which largely prolongs the product development cycle. To raise the design efficiency and reduce the complexity, modular design is becoming widely used in serial production of machine tools, especially large gantry machining centers. In this paper, we introduced a function and structure decomposition method to construct the function and structure correlations between components and employed a clustering method based on atomic theory to solve the module clustering problems. The clustering algorithm is modified by integrating the function and structure matrices in order that it applies to modularization of large machine tools. Furthermore, an evaluation method based on the concept of entropy is proposed here to evaluate and optimal select module partition schemes. Finally, we took the large gantry machining center QLMT6300 as an example and compiled the program with Microsoft Visual C++ 6.0 to illustrate the validity of the methods proposed. The presented clustering and evaluation method can be easily applied to different machine tools for modular design, reducing the work amount of designers. [ABSTRACT FROM AUTHOR]

The linear Navier-Stokes-Fourier (NSF) constitutive relations are derived on the assumption of the small deviation from local thermodynamic equilibrium, and consequently they may fail in describing flows removed far from local equilibrium, like rarefied hypersonic flows. In this paper, a nonlinear constitutive model of diatomic gases named as "nonlinear coupled constitutive relations" (NCCR) is presented. The model conceptually starts from Eu's generalized hydrodynamics and is developed for simulating rarefied hypersonic gas flows with a goal of recovering NSF's solutions in near-continuum regime and more accurate in transition regime. To enhance stable computation, an undecomposed algorithm is further developed for the nonlinear constitutive model within finite volume framework. An analysis is carried out to compare the algorithm with Myong's original decomposed algorithm. Local nonequilibrium flow regions are also investigated for rarefied hypersonic flows over a cone tip, a hollow cylinder-flare, and a hypersonic technology vehicle-type flying vehicle. The convergent solutions of NCCR model are compared with NSF, direct simulation Monte Carlo (DSMC) calculations, and experimental data. It is demonstrated from results of general flow-field and surface properties that the NCCR model is as computationally efficient as the NSF model in continuum regime, and, at the same time, more accurate in comparison with DSMC and experimental data than NSF in nonequilibrium flows. [ABSTRACT FROM AUTHOR]

Past studies of plasma sheaths enveloping vehicles have shown that the distribution of plasma is time-varying and results in communication and navigation problems. This paper aims to investigate the dynamic characteristics of the plasma sheath through the simulations of the Radio Attenuation Measurements-C II vehicle and the Apollo command module flowfields. The numerical methodology is based on the unsteady Reynolds-averaged Navier-Stokes model and the detached-eddy simulation model, and the thermochemical nonequilibrium effect is considered. The stable flows of both vehicles with a steady plasma sheath widely distributed in the shock-wave layer are first obtained. For the Radio Attenuation Measurements-C II vehicle, the dynamic plasma arising from the vehicle pitching oscillation has the same frequency as the vehicle oscillation, and the magnitude of the disturbance to plasma is related to the oscillation velocity. For the Apollo command module, the oscillation period of the electron density is the same as the evolution period of the vortex structures in the leeward regions. The time-varying surface electron density and pressure reveal a similar variation trend with the phase difference. In addition, the periodicity of the dynamic plasma disappears as the flow instability intensifies in the Apollo command module flowfields, whereas periodic plasma exists for a long time in the Radio Attenuation Measurements-C II vehicle oscillation flowfields. [ABSTRACT FROM AUTHOR]