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FeS2-embedded in porous carbon (FeS2/C) was prepared by simultaneous sulfidation and carbonization of an iron-based metal-organic framework precursor, and subsequently immobilized in polyvinylidene fluoride membranes (FeS2/C@PVDF) for organics removal via peroxymonosulfate (PMS) activation. The composition, structure, and morphology of the FeS2/C@PVDF membrane were extensively characterized. Scanning electron microscopy images manifest that the FeS2/C nanoparticles with an average diameter of 40 nm are assembled on the external and internal membrane surface. The as-prepared FeS2/C@PVDF membrane exhibits excellent performances over a wide pH range of 1.53-9.50, exceeding carbon-free syn-FeS2@PVDF. The effective degradation could be improved by inner pyrite FeS2 cores and thus enhanced the electron transfer between carbon shell and PMS. Electron paramagnetic resonance and quenching experiments elucidated that radical ( HO ∙ , SO 4 ∙ - ) and nonradical (1O2) species were the predominant reactive oxidants. In addition, FeS2/C@PVDF exhibited high stability with low Fe leaching (0.377 mg/L) owing to the effective protection of the outer carbon skeleton. Plentiful porosity of PVDF membranes not only affords a controlled size and confined uniform distribution of the immobilized FeS2/C nanoparticles, but also enables a persistent exposure of active sites and enhanced mass transfer efficiency. Our findings demonstrate a promise for utilizing the novel FeS2/C@PVDF membrane as an efficient catalyst for the environmental cleanup.

Background Examine the association of household financial indebtedness with depressive symptoms in old age, and investigate whether social network and support anticipation moderate the association. Methods Data were obtained from Sample Survey on Vulnerable Populations from Poor Families in Urban/Rural China (2018), with a sample of 5 934 older adults included. Center for Epidemiologic Studies Depression Scales was applied to measure depressive symptoms. Household indebtedness was measured in several ways, including whether the household was indebted, the amount of debts, and types of debts. We used the 6-item Lubben Social Network Scale to measure individual's social network. Socio-demographic, socioeconomic status and physical health variables were included as covariates. Results Household indebtedness, in form of being indebted and increased amount of debts, was associated with greater depressive symptoms in the Chinese elderly. The association of indebtedness and depressive symptoms may be driven by consumption and emergency debts. The moderating roles of social network and anticipation of support in the association of household indebtedness and depressive symptoms were found. Among those with household debts, older adults with larger size of social network and/or higher anticipation of being supported in the future reported with less symptoms of depressed. Limitations Due to a lack of information on the duration and debtor of household debt, we were not able to present a precise estimate for the exact impact of household indebtedness on mental health of elderly. Conclusion Familial financial strain was associated with aging mental well-being, increased social networks and social protections benefit aging health.

Benazir Income Support Program (BISP) is one of social protection programs providing unconditional financial assistance to poor women. The present study was conducted to explore the role of BISP in empowering women. This quantitative research was conducted in two districts of Punjab randomly selected out of 36 using face-to-face interviews with a sample size of 160 women beneficiaries of BISP. Research findings show that the majority of beneficiaries (78.8%) were married, with rural background (88%). A huge number (80%) of beneficiaries were illiterate. Similarly, overwhelming majority (81.9%) of respondents has labor as source of income. Most of the respondents were strongly agree (65%) and agree (95%) that the assistance should be more than Rs.5000/month or Rs.10000/month. Similarly, 69.4% and 71.3% of respondents agreed that female adults should take household decision and children should attend school regardless of gender. The government should provide appropriate assistance allowance for needy families especially for the empowerment of women. Moreover, the government should also launch massive programs to maximize girls' education with motive to empower women.

Side information has been shown useful for improving the performance of matrix completion applications. However, in most cases, only partial side information of either the column or row space is available. In this work, we propose a novel regularization based model to incorporate partial side information in matrix completion. We provide theoretical guarantees to ensure the success of the proposed model. It is proved that the proposed model achieves the state-of-the-art sample complexity when the given partial side information is exact, and an error bound for inexact partial side information is also provided. Moreover, we provide a deterministic rule for the selection of regularization parameter. We conduct extensive experiments on both synthetic and real-world data-sets. Experimental results show that our model succeeds to incorporate partial side information, and outperforms the state-of-the-art models on most data-sets.

The coexistence of minerals, heavy metals and microplastics in sediment has been widely reported, while the interactions between minerals and heavy metals may be affected by the presence of microplastics. Therefore, to elucidate the effect of microplastics on the interactions between heavy metals and sediment minerals, this study conducted a series of experiments using polystyrene (PS) microplastics, Pb/Cr/Cd and ferrihydrite (Fh). The presence of PS microplastics with ferrihydrite (Fh-MPs200, mass ratio of ferrihydrite to PS of 200:1) improved the adsorption capacity of ferrihydrite, especially with an increase of 36 % for Pb. Morphological characterization demonstrated that the nano-ferrihydrite particles were dispersed on the surface of the PS microplastics, increasing the available reaction sites of the ferrihydrite particles. Furthermore, the results of zeta potential and pH effect showed that the reduction in electrostatic repulsion after adding PS was another critical reason for the increase in Pb adsorption by Fh-MP200. As a result, the presence of PS microplastics enhanced the complexation of Pb ions and the hydroxyl groups on the ferrihydrite surface. This study demonstrated that the presence of microplastics in the sedimentary environment can alter the dispersion and surface properties of minerals, thereby affecting the accumulation and transportation of heavy metals at the water-sediment interface.

Due to the influence of residual stress on material properties, residual stress measurement is particularly important for the optimization of structure designs and the condition monitoring of machines. In this paper, the influence of residual stress on materials nonlinearity was reported. Firstly, the propagation model of ultrasonic surface waves was established by the finite element method and the effect of frequency was studied to determine an appropriate frequency of acoustic nonlinearity parameters. Then, the different residual stresses were produced into specimen by adding internal stress in the material and the impact on acoustic nonlinearity parameter was studied. The results show that the nonlinearity of the material increases monotonously with the increase of residual stress. Experiments were done by using the nonlinear ultrasonic surface wave on three 7075Al alloy specimens under different residual stresses. Experimental data matched well with the simulation results. It has been shown that the nonlinear ultrasonic surface wave method has great potential in the residual stress detection and evaluation.

A rapid growing number of cases on victimization among left-behind children were reported and child victimization has become an important social issue in China. The frequent victimization events, together with its negative impact, lead the Chinese government to actively embark on innovation in protection service against victimization for left-behind children, especially at school and community levels. Drawing on representative data from Survey on Children and Old Adults Left-behind in Rural China, this study aims to test whether school-based and community-based protection service innovations have significant association with left-behind children's victimization incidence in China. According to the regression results, this study found that there was significantly negative association between protection service and victimization incidence among left-behind children in China. To be specific, school-based protection service was significantly associated with left-behind children's lower victimization incidence, and furthermore, combined protection service (both school-based and community-based protection services), which has significantly negative association with victimization incidence as well, achieved a more pronounced effect than school-based protection service only. Protection service innovations launched by Chinese government were proved to be effective in protecting left-behind children from victimization. The government shall lay more emphasis on innovation in protection service, as well as speed up the implementation of protection service policy nationwide.

Despite extensive research on carbon dots (CDs), rare studies have been performed on the photostability of CDs. Here, the photostability of CDs synthesized with 3-aminobenzoic acid were systematically investigated under different pH conditions (5.0, 7.4 and 9.0). The results showed that under Xenon lamp irradiation, the fluorescence (FL) intensity of the CDs exhibited an increase first and then a decrease, with a gradual shift of the maximum emission wavelength to longer wavelength. Further investigation indicated that the irradiation induced the change of the CD surface functional groups and gave rise to aggregation, resulting in the formation of larger particles. This study provided important reference value towards research on CDs properties.

This study aims at study effects of blending long-chain alcohol (n-butanol or n-pentanol) with diesel on the spray characteristics and compare the differences of those spray characteristics between n-butanol-diesel blends and n-pentanol-diesel blends. Results showed that with the addition of long-chain alcohols, the spray tip penetration decreased, the spray cone angle increased and the spray area increased, while with the increasing proportions of long-chain alcohols in blended fuels, the spray area decreased whereas the peak tip velocity increased. Under the same blended ratios, n-butanol-diesel blends showed longer tip penetration, larger cone angle, larger spray area and lower peak tip velocity compared to n-pentanol-diesel blends in the same injection conditions. Furthermore, from the comparison between spray morphology of each tested fuel with each other, it can be inferred that n-butanol-diesel blends have largest spray areas and thinnest spray boundaries, followed by n-pentanol-diesel blends and then pure diesel fuel.

Earth fissures are a geologic phenomenon that mainly affects the medium with shallow surface soil and mainly developed in the Quaternary sediment cover. In the Yellow River-Qinghe River - Zhanghe River shallow buried paleochannel Band (HQZ-Qh2-II Band) on the North China Plain, 93 earth fissures are developed. Among them, 29 fissures are evolved in the Daming zone in the upper reaches of the paleochannel band. Thus, the zone belongs to a densely grouped fissure area. This study, through a series of field trenching and surveying, revealed that these earth fissures have unique plane distribution rules and profile structure features of short length (several meters to several hundred meters), shallow depth (smaller than 10 m) and good correspondence to Daming paleochannels. These basic characteristics reveal that unlike other tectonic earth fissures, Daming earth fissures are a new and unknown type of fissures, i.e., paleochannel-controlled earth fissures. Theoretical analysis of their features showed that they were formed due to the actions of gravity, primary joint factors and groundwater pumping activities and controlled by ancient river factors including paleochannels, sediments and groundwater. Among them, the process of Mode I can be summed up as “self-gravity action - tensile cracks - surface water scouring - earth fissures”. The process of Mode II is “primary join - surface water infiltration - piping - cave in - earth fissures”. The process of Mode III is “groundwater extraction - aquifer compression - inhomogeneous ground subsidence - earth fissures”. These formation mechanisms of paleochannel-induced earth fissures can be used to predict the fine distribution of shallow buried paleochannels and the overall migration process of the rivers. Thus, this kind of earth fissures is of great significance for understanding the underground paleogeomorphology (buried paleochannel) of the North China Plain and other alluvial plains of the world.

The study of aerated irrigation (AI) in conjunction with different irrigation levels on economic and environmental effects has important scientific significance for the selection of optimal irrigation and reasonable greenhouse management practices. In this paper, a two-year experiment was conducted to investigate tomato yield, water use efficiency (WUE), CO2, N2O, CH4 emissions, net global warming potential (NGWP), and carbon footprint (CF) differences for a greenhouse tomato system in Northwestern China in 2016 and 2017. Based on the amount of irrigation needed to provide an adequate water supply (W), 60%W, 80%W and 100%W were set as the three irrigation levels, with two aeration regimes (aeration and control), totaling six treatments. Compared to the control, AI significantly increased tomato yield by 32.0%, WUE by 32.0% and CF by 24.0% on average (p 0.05). With respect to the treatment of 100%W, 80%W over the two years had no obvious effect on tomato yield, WUE and CF (p>0.05), while 60%W reduced yield by 23.4% and CF by 32.6% but increased WUE by 35.1% significantly (p 0.05). The main inputs in this arid and semi-arid region were electricity for irrigation and fertilizers, contributing 87.9%–92.9% of the total impact. Overall, the treatment of aerated full irrigation was suitable for crop production, water saving and carbon sequestration with WUE of 24.05 (in 2016) and 19.95 kg m−3 (in 2017), a net greenhouse gas intensity of 0.103 (in 2016) and 0.086 (in 2017) t t−1, and with a carbon footprint per tomato yield of 0.350 (in 2016) and 0.426 (in 2017) kg CO2-eq kg−1.

Chatter monitoring is an essential requirement for high-precision machining systems. Chatter vibration is characterized by amplitude modulation when the beat-frequency effect or geometric eccentricities exist, which hinders methods based on the transient characteristic index. Here, moving average difference spectrum analysis (MADSA) is proposed for detection of modulated chatter; the method can detect chatter frequency and track its amplitude from low signal-to-noise vibration signals early on. MADSA utilizes a moving average to smooth the amplitude trend of chatter frequency candidates obtained by the difference spectrum analysis, and the chatter frequency is detected using monotonicity analysis. MADSA was validated in both simulations and gear-milling machine experiments, and comparisons between wavelet packet-energy entropy method and MADSA are described, to illustrate the performance of the latter.

Angle beam wedge transducers are widely used in nonlinear Rayleigh wave experiments as they can generate Rayleigh wave easily and produce high intensity nonlinear waves for detection. When such a transducer is used, the spurious harmonics (source nonlinearity) and wave diffraction may occur and will affect the measurement results, so it is essential to fully understand its acoustic nature. This paper experimentally investigates the nonlinear Rayleigh wave beam fields generated and received by angle beam wedge transducers, in which the theoretical predictions are based on the acoustic model developed previously for angle beam wedge transducers [S. Zhang, et al., Wave Motion, 67, 141–159, (2016)]. The source of the spurious harmonics is fully characterized by scrutinizing the nonlinear Rayleigh wave behavior in various materials with different driving voltages. Furthermore, it is shown that the attenuation coefficients for both fundamental and second harmonic Rayleigh waves can be extracted by comparing the measurements with the predictions when the experiments are conducted at many locations along the propagation path. A technique is developed to evaluate the material nonlinearity by making appropriate corrections for source nonlinearity, diffraction and attenuation. The nonlinear parameters of three aluminum alloy specimens – Al 2024, Al 6061 and Al 7075 – are measured, and the results indicate that the measurement results can be significantly improved using the proposed method.

Coal slime, a low-calorific-value fuel, is a by-product during coal washing, which can be disposed in quantity and fully utilized in circulating fluidized bed (CFB) boiler. This research paid attention to the ignition and combustion behaviors of single coal slime particles, which affect the normal combustion, operation stability and burning efficiency in circulating fluidized bed boiler. The ignition and combustion behaviors including ignition mechanism, ignition delay, ignition temperature and combustion process of single coal slime particles in a vertical heating tube furnace in CO2/O2 atmosphere were researched under different operation condition parameters, for different gas temperatures (Tg = 923, 1073, and 1173 K), gas flow rates (V = 0–20 L/min), and oxygen mole concentrations (O2% = 5–80%). Coal slime particle had three ignition mechanisms in CO2/O2 atmosphere, namely, homogeneous ignition of volatiles at the windward and leeside of particle, heterogeneous ignition of char and heterogeneous ignition of coal. Only heterogeneous ignition of char and homogeneous ignition of volatiles at the windward of particle occurred in quiescent atmosphere. However, homogeneous ignition region decreased while heterogeneous ignition region increased gradually with the increasing flow rates in the oxygen concentration-gas temperature plane. Different ignition mechanisms were accompanied with various combustion processes. The combustion processes corresponding to heterogeneous ignition of char changed from flameless combustion to flaming combustion as oxygen concentration increased. Moreover, the critical oxygen concentration elevated from 30% to 50% with the increasing flow rate. The ignition temperatures and ignition delays decreased with the increasing gas temperature and oxygen concentration. As the flow rate increased, the trends became more obvious in medium-to-low oxygen concentrations. Compared with the ignition characteristics and combustion processes of coal slime particles in N2/O2 atmosphere, those in CO2/O2 atmosphere were suppressed due to the higher mole heat capacity and lower diffusion rate of oxygen molecule in CO2.

Poly-victimization of children attracts increasing concerns in China, and a rapid growing number of cases on poly-victimization among left-behind children were reported. This study aims to test the association and mediating mechanism between poverty and poly-victimization of left-behind children in rural China. Representative survey data on left-behind children in rural China was analyzed in this study. Frequency and percentage were reported in descriptive analyses; Logistic Regression and mediating effects analysis were employed to test the association and detailed pathways between poverty and poly-victimization. About 27.50% of left-behind children suffered from at least one kind of victimization, and >10% suffered from poly-victimization (at least two kinds of victimization in the present study). Regression results revealed that poverty was significantly and consistently associated with poly-victimization when controlling for covariates. Furthermore, the mediating mechanism analysis showed that, in the association between poverty and poly-victimization, it is the increased vulnerability from individual (individual psychological and behavioral health) and family (quality of family care) rather than vulnerability from surrounding interactions, plays a significant mediating role. This study stresses the importance of poverty alleviation in policy making for the protection of left-behind children from victimization in China. Also, support from family and school in protecting left-behind children should be paid additional attention.

Exploring highly stable and efficient non-precious metal catalysts for decontamination of various non-biodegradable contaminants is a major challenge. Herein, Fe, Cu-coordinated ZIF-derived bimetal encapsulated N-doped carbon nanotubes (Fe-Cu@N-C) were developed and employed as novel bifunctional catalysts for organic oxidation and CrVI reduction. Pyrolysis of ZIF-8 containing Fe2+ and Cu2+ has successfully produced Cu nanoparticles and atom-dispersed Fe bimetals embedded in N-doped carbon nanotube catalysts. It was observed that the obtained optimal Fe-Cu@N-C possessed outstanding activity and stability for efficient degradation of organic contaminants via PMS activation, and toxic CrⅥ reduction with Formic acid (FA) as the reductant. Singlet oxygen (1O2·) was verified as the dominant active species for organic oxidation, while surface-adsorbed atomic hydrogen (H*) was responsible for effective reduction of CrVI to CrIII in the Fe-Cu@N-C/FA system. Compared with other ZIF derived systems such as Fe@N-C, Cu@N-C, and metal-free N-C, Fe-Cu@N-C exhibited prominent catalytic activities, which were attributed to bimetallic active sites (Fe-Nx and Cu-Nx), high N-doped level, large surface area and conductivity of porous carbon structure for fast mass and electron transport. This report provides a new approach to design highly efficient multifunctional catalysts for the purification of water to remove various types of pollutants.

Sensors for detecting slippage are widely used in various types of end-effective devices, and the performance of these sensors is one of the most important indicators of a robot's "soft gripping" ability. At present, sliding detection is mainly based on piezoelectric materials, acousto-electric principles, photoelectric sensing, etc. But the above-mentioned sensors have complex structures and signal processing processes, and they all require external power supply during operation. This paper proposes a self-powered sliding tactile sensor based on triboelectric effect and electrostatic induction, which uses the electrical signal generated by the sliding of the object as the detection signal by the triboelectric nanogenerator, and the detection of sliding speed and sliding distance can be realized at the same time. In addition, it can also realize the judgment of the force loading and unloading of the object to be grasped. Furthermore, we developed a non-contact working mode of the sliding tactile sensor, which can realize sliding detection without direct contact with the object. This work provides a feasible solution for the intelligent detection of a new generation of end effector.

The ignition characteristics and combustion processes of single coal slime particle in a vertical heating tube furnace in N2/O2 oxidant atmosphere were investigated under different hot-coflow conditions, including variations in coflow temperature (Tc = 923, 1073, and 1173 K), gas flow rate (V = 0–30 L/min), and oxygen concentration (O2% = 5%–100%). All investigated hot-coflow conditions exhibited three ignition behaviors, homogeneous ignition of volatiles, heterogeneous ignition of char, and heterogeneous ignition of coal. Additionally, three corresponding ignition regimes were observed in the oxygen concentration-coflow temperature plane. Critical conditions for the transitions of the three ignition mechanisms varied as flow was increased from 0 to 30 L/min. Various ignition mechanisms resulted in various combustion processes. Under medium-to-low oxygen concentration and low coflow temperature, the heterogeneous ignition of char resulted in flameless combustion. The ignition temperature and ignition delay decreased as coflow temperature and oxygen concentration were increased. The trends became more obvious when test conditions progressed in medium-to-low oxygen concentrations. As the flow rate increased, ignition temperature and delay became increasingly sensitive to oxygen concentration. Experimental results are then discussed in conjunction with the various observed trends influencing mechanisms of different hot-coflow conditions.

Solution-processed solar cells are promising as low-cost alternatives to the first-generation solar cells. Combining two solution-processed devices in a tandem structure can potentially achieve a high efficiency while maintaining a relatively low fabrication cost. Here we present a tandem combining solution-processed perovskite and CZTSSe solar cells in a reflective configuration. The perovskite cell with a large bandgap acts as a spectral filter reflecting the sub-bandgap photons to a low bandgap CZTSSe cell. A total efficiency of 16.1% has been obtained in a four-terminal measurement, higher than each of the sub-cells. These results show the potential of solution-processed tandem solar cell with perovskite and kesterite in achieving a high efficiency with a low fabrication cost.

This paper introduces a sparse total focus method (TFM) as a viable solution to the trade -off between the imaging precision and computational efficiency. A corrected two-layer TFM algorithm is first established; then the element layout in the sparse arrays is optimized by the genetic algorithm to improve the spatial resolution and contrast resolution. Using the effective aperture theory, the weighting functions of the optimized sparse array elements are investigated, and the corrected sparse-TFM algorithm is developed. Experiments are conducted on the side-drilled holes in a wedged specimen. Results indicate that the proposed sparse-TFM can greatly increase the computational efficiency while maintaining a relatively low error.

The pulse-echo nonlinear acoustic wave fields generated by focused transducers are calculated numerically and verified experimentally. Simulation results show that in the reflection direction, phase differences between newly generated second harmonic and reflected waves are about π/2, regardless of the rigid and stress-free boundaries; thus, the total second harmonic wave will neither be strongly enhanced nor be cancelled. Experiments are conducted with a focused transducer working in pulse-echo mode and the measured amplitudes of nonlinear waves reflected after water-air and water-aluminum/steel interfaces agree with the simulated results. This work helps advance applications using pulse-echo nonlinear acoustics.

Nonlinear Rayleigh wave fields generated by an angle beam wedge transducer are modeled in this study. The calculated area sound sources underneath the wedge are used to model the fundamental Rayleigh sound fields on the specimen surface, which are more accurate than the previously used line sources with uniform or Gaussian amplitude distributions. A general two-dimensional nonlinear Rayleigh wave equation without parabolic approximation is introduced and the solutions are obtained using the quasilinear theory. The second harmonic Rayleigh wave due to material nonlinearity is given in an integral expression with these fundamental Rayleigh waves radiated by the wedge transmitter acting as a forcing function. Multi-Gaussian beam (MGB) models are employed to simplify these integral solutions and to extract the diffraction and attenuation correction terms explicitly. The effect of nonlinearity of generating sources on the second harmonic Rayleigh wave fields is taken into consideration; simulation results show that it will affect the magnitude and diffraction correction of the second harmonic waves in the region close to the Rayleigh wave sound sources. This research provides a theoretical improvement to alleviate the experimental restriction on analyzing the effects of diffraction, attenuation and source nonlinearity when using angle beam wedge transducers as transmitters.

Efficient and accurate nondestructive testing of surface or sub-surface flaws is essential for metal components. This study focuses on the high-quality image reconstruction of these flaws. An imaging detection method is introduced which combines the leaky Rayleigh waves testing and the synthetic aperture focusing technique (SAFT) with an immersion pulse-echo scanning. The principal component analysis (PCA) is used to reduce the noise of the leaky Rayleigh waves, and then the imaging is obtained using the SAFT algorithm. The experimental results show that the PCA-SAFT imaging method can reduce structural noise and imaging artifacts comparing with the B-scan imaging method. The lateral resolution of defects is improved and the mean error of defects sizing can be reduced by 48.81%. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the ultrasonic image are increased by 6.95 dB and 4.20 dB respectively. The proposed method can be a new choice for effective evaluating the surface quality of key components.

Early crack signals in critical infrastructure components of major equipment are hardly to be extracted due to its low signal noise ratio (SNR). A de-noising method combined wavelet packet (WP) technology with sparse code shrinkage (SCS) is proposed in this study. Firstly, WP reconstruction technology is used to reserve the crack signal with a specified frequency range. That is, the signal is decomposed by Meyer wavelet into five layers, and the signal with the frequency range from 187.5 kHz to 609.375 kHz is reserved. Then SCS method removes noise within the specified frequency range. Namely, the probability density function (PDF) of the signal independent coefficients is estimated via the generalized Gaussian model (GGM) in the independent component analysis (ICA) space. The nonlinear de-noising is finished by utilizing maximum a posteriori (MAP) estimate. The results obtained by the combined method are compared with those generated by the SCS method and the WP de-noising method. It demonstrates that the combined method is the best one among the three methods in extracting weak signals. Its output SNR is −2.38 dB and the correlation coefficient (CC) is 0.54 when the input SNR is −20 dB. They are higher than those obtained by the SCS method (SNR −4.46 dB and CC 0.51). The WP method is the worst (SNR −3.54 dB and CC −0.003). Therefore, the combined method is quite suitable for weak signal extraction.

A three-dimensional finite element model is developed to simulate multi-layer deposition of AlSi10Mg in selective laser melting (SLM) by using commercial ANSYS software. The temperature distribution, thermal history, molten pool depth, remelting depth, cooling rate and solidification morphology parameter in multi-layer buildup process are investigated. Furthermore, the effect of laser energy input on the melting and solidification process is evaluated. The results show that the temperature and molten pool depth gradually increases with new layers and energy input. The cooling rate increases progressively while the solidification morphology parameter decreases with the increase of energy input. It leads to obtain fine grains with low energy input. To verify the accuracy of simulated results, experiments are performed. Compared simulated results with experimental ones, good agreement is obtained.

Artificial sweeteners (ASs) are emerging polar organic contaminants, which can chelate with heavy metals in the environment. Recently, the ASs have been widely detected in the aquatic environment. However, little is known about the influence of ASs on the mobility and toxicity of heavy metals associated in sediment. In the present study, the release of heavy metals from a lake sediment and the toxicity to a green algae Scenedesmus obliquus were examined in the presence of two most frequently detected ASs, acesulfame and sucralose, and humic acid (HA), respectively. The existence of 1.00–100 mg/L of acesulfame, sucralose, and HA enhanced the release rates (Rrelease) of Cd, Cu, and Pb from the virgin lake sediment significantly by up to 46.7%, 86.0%, and 79.9%, respectively. Further, the results from microcosm experiments revealed that the existence of 1.00–10.0 mg/L of acesulfame, sucralose, and HA in the water phase prompted the release and toxicity of heavy metals associated with Cd- and Cu-spiked sediment, and the promotion capacity followed the order of HA > acesulfame > sucralose. The inhibitions on cell-specific growth rate (μ) of the algae were found increasing significantly with the elevated levels of acesulfame and HA (p

We develop a new relativistic model which can describe the dynamics on electron-impact excitation (EIE) of ions within a quantum plasma environment. An exemplary excitation 1s1/2 → 2p3/2 of Fe XXVI by electron impact with the exponential cosine-screened Coulomb potential (ECSCP) is presented, i.e., 25 times ionized atoms of Fe, exist in laser-produced plasmas, astrophysical objects, and electron beam ion trap experiments. For the atomic structure of target ion, using the same potential, a Ritz variational method with a trial wave function that contains unknown variational parameters is also proposed for comparison purposes. In this method, an analytical formula of bound energy is derived from the energy equation, and the variational parameters are determined by the minimization of the energy. The energies obtained from our two methods are compared with each other and other theoretical predictions based on the non-relativistic model and found to be in good agreement. For the collision dynamics, the continuum wave function is determined by solving the modified Dirac equations, in which the ECSCP is included for the solution of the continuum orbital. The total cross sections, magnetic sublevel cross sections, and the degrees of linear polarization of emitted x-rays are calculated as a function of the incident energy and screening parameter by using the distorted-wave method in the relativistic frame. Since there are no experiments or other calculations for EIE cross sections on this ion, the obtained results have been compared with those for an isolated ion. The effect of quantum plasma leads to a reduction in the total and magnetic sublevel cross-sections and thus reduces the degrees of linear polarization of emitted x-rays. Comparative analysis allows to estimate the quality of the proposed approximations. Our dynamic model is practicable and easy to apply, which may provide an alternative route towards information with fluorescence polarization in a quantum plasma environment.

An evaluation model based on the multi-scale ultrasonic attenuation coefficient was developed to control both systematic error and random error. AISI 304 stainless steel was used to validate the presented model. Wavelet transformation was used to obtain the variation of ultrasonic signal over time and scale. Particle swarm optimization was utilized to correlate the coefficient with grain sizes. The model shows the attenuation of all scales increased with the grain size, and ultrasound attenuates faster on smaller scales. Compared with the ultrasonic velocity method and the traditional attenuation method, the proposed method has less systematic error and random error.

In most object tracking algorithms based on sparse representation, the optimization problem is often formulated as an l1 or l2 minimization problem, because its primal l0-norm minimization problem is NP-hard. In this paper, a visual tracking method is proposed based upon l0-norm minimization which directly seeks solution to the primal l0 problem. To avoid solving a large number of l0 minimization problems, we introduce to encode all samples simultaneously in a multi-task manner, which means that the number of minimization problem to be solved is only one, and an algorithm is presented to solve the minimization problem. Our tracking algorithm is then implemented under the framework of particle filter. Experiments on different challenging video sequences demonstrate that our method can achieve robust tracking results.

With China's urbanization and its development in market economy, mass rural-to-urban migration greatly expanded over the past decades. Consequently, migrant and left-behind children have greatly increased in number. Using data from the 2011 Survey on Social Integration of Migrant Children in Wuhan, China, this study examined psychological and behavioral problems of migrant and left-behind children. Results showed that left-behind and migrant children had poorer psychological and behavioral outcomes than local children. However, the difference disappeared after controlling for family and school characteristics. The findings provided implications on improving psychological and behavioral outcomes of migrant and left-behind children through family intervention and education policy reform.

The transformation of acesulfame in water under environmentally relevant conditions, including direct and indirect photolysis, biodegradation, and hydrolysis, was systematically evaluated. Under natural sunlight, both direct and indirect photolysis of acesulfame were negligible in sterilized systems at neutral or alkaline pH, whereas direct photolysis occurred at pH of 4 with a rate constant of 0.0355 d−1 in deionized water. No significant reduction in acesulfame contents was found in the dark controls or in the incubation experiments, indicating acesulfame was resistant to hydrolysis and biodegradation. In unsterilized systems, photolysis was substantially enhanced, implying that there was a joint effect of photolysis and biodegradation or that the sterilization process had the secondary effect of inactivating some photosensitizers. The near-surface summer half-life of acesulfame in the water from the Haihe River was 9 d. Specific experiments revealed the involvement of 1O2/3DOM* in acesulfame photolysis, whereas OH exhibited only a slight contribution in the presence of DOM or bicarbonate. As indicated by the total organic carbon data, no significant mineralization occurred in both sterilized and unsterilized systems after acesulfame was irradiated under simulated sunlight for 7 d, suggesting the generation of persistent intermediates. Finally, major degradation intermediates were analyzed, and the degradation pathways of acesulfame under environmentally relevant conditions were proposed for the first time.

The advanced accumulator is designed to improve the safety and reliability of CPR1000 by providing a small injection flow to keep the reactor core in flooded condition. Thus, the core still stays in a cooling state without the intervention of low pressure safety injection and the startup grace time of the low pressure safety injection pump can be greatly extended. A new model for the advanced accumulator, which is based on the basic conservation equations, is developed and incorporated into RELAP5/MOD 3.3. The simulation of the advanced accumulator can be carried out and results show that the behavior of the advanced accumulator satisfied its primary design target. There is a large flow in the advanced accumulator at the initial stage. When the accumulator water level is lower than the stand pipe, a vortex appears in the damper, which results in a large pressure drop and a small flow. And then the sensitivity analysis is performed and the major factors which affected the flow rate of the advanced accumulator were obtained, including the damper diameter, the initial volume ratio of the water and the nitrogen and the diameter ratio of the standpipe and the small pipe. Additionally, the primary coolant loop cold leg double-ended guillotine break LBLOCA in CPR1000 with advanced accumulator is analyzed. The results show that the criterion for maximum cladding temperature limit (1477 K) ( NRC, 1992 ) can be met ever with 200 s after the startup of the low pressure safety injection. From this point of view, passive advanced accumulator can strive a longer grace time for LPSI. Thus the reliability, safety and economy of the reactor system can be improved.

A sandwich structural CoS/graphene sheet (CoS/GS) electrode was prepared by repeating electrophoretic deposition of graphene sheets and deposition of CoS nanoparticles. We found the graphene sheets play a key role in controlling the morphology of the nanostructure. The obtained CoS/graphene nanocomposite counter electrode has a high specific surface area and displays an excellent electrochemical activity toward the polysulfide electrolyte. Consequently, the quantum dot-sensitized solar cell based on CoS/GS counter electrode shows an improved photovoltaic performance.

Cu2ZnSnS4 (CZTS) can be potentially used as a counter electrode in dye-sensitized solar cells (DSSCs) because of its excellent catalytic performance. In this paper, stoichiometric CZTS was prepared and was applied in DSSCs. The DSSCs with CZTS counter electrodes showed relatively low photoelectric conversion efficiency (PCE) of 4.77%. However, the PCE was clearly enhanced by adding graphene to CZTS and a maximum PCE of 7.81% was achieved, which was superior to the value of 6.66% shown by the Pt counterpart. The influence of graphene that results in the improvement of the performance of the DSSCs is discussed in detail.

To improve dye adsorption and conversion efficiency of dye-sensitized solar cells (DSSCs) based on electrospun TiO 2 nanofibers, surface treatment combining acidification and oxygen plasma treatment has been adopted. TiO 2 nanofiber cell with a thickness of ∼50 μm gives a conversion efficiency ( PCE ) of 7.96%. After acidification, PCE is increased to 8.59%. Subsequently O 2 plasma treatment further improves the PCE to 9.33%, reflecting a 17% increase compared to the cell without surface treatment.

The biosorption characteristics of Cs(I) ions from aqueous solution using exopolymers (PFC02) produced from Pseudomonas fluorescens C-2 were investigated as a function of pH, biosorbent dosage, contact time and initial concentration. pH played a major role in the adsorption process, and the optimum pH for the removal of Cs(I) was 8.0. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models were applied to describe the biosorption isotherm of the Cs(I) ions by PFC02. The Lagergren first-order, pseudo second-order kinetic and intraparticle diffusion models were used to test the kinetic data. Langmuir model and D-R model fitted the equilibrium data better than the Freundlich isotherm. The monolayer adsorption capacities of PFC02 as obtained from Langmuir isotherm at 25 degrees C was found to be 32.63 mg/g. From the D-R isotherm model, the mean free energy was calculated as 26.73 kJ/mol, indicating that the biosorption of cesium was chemisorption. The biosorption process was rapid, and the kinetic rates were best fitted to the pseudo second-order model, which indicated the biosorption process operated through chemisorption mechanism. FT-IR analysis of PFC02 showed the possible functional groups responsible for cesium adsorption were hydroxyl, carboxyl, carbonyl and sulphonate groups. SEM analysis showed the porous structure of the material while EDX analysis confirmed the adsorption of Cs(I) on PFC02. Cesium adsorbed onto the PFC02 could be desorbed efficiently using 1 mol/L HNO3, and the enrichment factor was 50.0. Furthermore, PFC02 could be reused five times with only about 8.25% regeneration loss. The developed method was successfully utilized for the removal of Cs(I) ions from aqueous solution.

This paper assesses the sustainable biomass resource for energy in China. Assessment has been carried out for the following resources: (i) agricultural residues, (ii) forest residues, and (iii) municipal solid waste (MSW). The potential of each resource is estimated for the base years 2008, 2008, and 2007. The energy potentials of these resources in 2008, 2008, and 2007 are estimated to be 14.7, 3.9, and 0.2 EJ, respectively. The total potential including the energy of 6.4 EJ from the proposed low-input high-diversity (LIHD) grassland biomass on the untilled lands for the base years 1996 is equal to about 30.2% of China’s energy consumption in 2008. Furthermore it is projected that sustainable biomass use for energy will reduce net emissions of green house gases (GHG) of 3276.7 million tonnes, and help in emission-reduction target of China and the world.