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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.

Tandem solar cells combining a wide bandgap, efficient perovskite absorber with a low bandgap photovoltaic module, such as a c-Si cell, can potentially achieve a high theoretical efficiency of over 30%. Instead of using the conventional parallel stacking tandem, we report here a reflective tandem configuration, with the perovskite solar cell acting as the spectral filter that absorbs high energy photons, while sub-bandgap photons are reflected to a Si sub-cell using a highly reflective back metal electrode. The perovskite solar cell exhibits a high reflectance of over 60% in the near infrared spectral region, which allows the subsequent silicon cell to absorb photons in this region, resulting in a high current density of 13.03 mA cm−2. In such a tandem configuration, we achieved a combined efficiency of 23.1% using a four-terminal measurement. This result demonstrates the promise of employing perovskite solar cells in a reflective tandem for a high efficiency solar energy conversion system, with an efficiency of up to 30%.

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.

Phosphorus (P) in the river sediment plays an important role in the fate and transport of heavy metals at sediment-water interface of the aquatic eutrophication environment. To explicate the effect of P loading, the sediments with different P contents were employed in this study to experimentally investigate the adsorption/desorption of Pb2+ and Cd2+ and the releasing behavior of P during the adsorption/desorption processes. Results illustrated a strong affinity between Pb2+ ions and the P-containing sediments in both single Pb and binary Pb + Cd systems. In single-metal systems, the Pb2+ adsorption capacities of all types of sediments (15.04–19.44 mg g−1) were higher than those for Cd2+ (4.68–5.56 mg g−1). While in binary-metal systems, the Pb2+ adsorption was slightly influenced by the coexisting Cd2+, but the Cd2+ adsorption capacities were decreased by over 5 times. Moreover, the adsorption amount and retention ability of Pb2+ on sediment were enhanced by increasing content of P in the sediment. Meanwhile, the releasing of P was also closely depended and significantly inhibited by the Pb2+ attached on the sediment. The P release amounts during the desorption processes of Pb- and Pb + Cd-loaded sediments were over 50 times lower than those from the raw sediments (sediments without heavy metals adsorbed), but the values decreased by a factor of two for the single Cd-loaded sediments. Furthermore, the results of X-ray photoelectron spectroscopy indicated the crucial role of P loading in Pb transport in the sediment and overlaying water. The findings in this study showed important implications for the transport of heavy metals and P at the sediment-water interface and offered new insights for further explicating the mechanisms of secondary pollution caused by heavy metals and P in aquatic eutrophication environment.

Organic-inorganic hybrid perovskites have emerged in recent years as one of the most promising materials for solution-processed electronics and optoelectronics including solar cells, light-emitting diodes (LED) and field-effect transistors (FET). Combining the rigid inorganic framework with soft organic materials, these hybrid perovskites provide the opportunity for investigating organic-inorganic interactions at the molecular scale. Using a molecular approach, this Ph.D. work explored a series of novel organic-inorganic hybrid perovskites targeting luminescence-related applications including LEDs and color-conversion phosphors. The structure-property relation was investigated and the underlying photophysical mechanism for the versatile luminescence was studied. The applications of these perovskites as light emitters in multicolored LED, white LED and long-lifetime phosphors were demonstrated... Doctor of Philosophy

Background: Few studies have examined intrinsic motivation that is related to turnover intention among geriatric nurses employed in nursing homes in China.Objectives: This study aims at investigati...

Recent references have showed crucial roles of several miRNAs in neural stem cell differentiation and proliferation. However, the expression and role of miR‐485‐3p remains unknown. In our reference, we indicated that miR‐485‐3p expression was down‐regulated during NSCs differentiation to neural and astrocytes cell. In addition, the TRIP6 expression was up‐regulated during NSCs differentiation to neural and astrocytes cell. We carried out the dual‐luciferase reporter and found that overexpression of miR‐485‐3p decreased the luciferase activity of pmirGLO‐TRIP6‐wt but not the pmirGLO‐TRIP6‐mut. Ectopic expression of miR‐485‐3p decreased the expression of TRIP6 in NSC. Ectopic miR‐485‐3p expression suppressed the cell growth of NSCs and inhibited nestin expression of NSCs. Moreover, elevated expression of miR‐485‐3p decreased the ki‐67 and cyclin D1 expression in NSCs. Furthermore, we indicated that miR‐485‐3p reduced proliferation and induced differentiation of NSCs via targeting TRIP6 expression. These data suggested that a crucial role of miR‐485‐3p in self‐proliferation and differentiation of NSCs. Thus, altering miR‐485‐3p and TRIP6 modulation may be one promising therapy for treating with neurodegenerative and neurogenesis diseases.

Background In 2016, the tiered healthcare model featuring “specialists + general practitioners + health managers” in Xiamen was recognized by the Medical Reform Office of State Council and was promoted as a model to replace hospital-centric care with community-based care. This study evaluated the impact of the Xiamen's tiered healthcare system reform on health outcomes and healthcare spending among chronic disease patients. Methods Data were derived from Xiamen's electronic health record (EHR) and medical claims systems. The sample included 154,651 individuals with hypertension and 50,722 individuals with diabetes from Xiamen between 2012 and 2016. The dependent variables included rates of disease under control and total treatment costs. Patients were grouped by the types of chronic disease management: precision management, regular management, or without management. Kaplan-Meier, Cox survival analysis and PSM + DID method (Propensity score matching and difference-in-difference method) were used to compare the management outcomes by group. Findings The precision management group showed better clinical quality performance than the regular management group. Under-control disease rates in the precision management group showed a continuous improvement trend, while the regular management group showed a ceiling effect after ten months. Under-control rates in the precision management group increased over 40% for hypertension and over 30% for diabetes, higher than that increases found in the regular management group. Reform was also associated with consistent reductions in annual per capita total treatment costs across groups. The cost-savings in the precision management group between 2014 and 2016 was 381 Chinese yuan (CNY) for hypertension and 1117 CNY for diabetes, compared with the group without management. Interpretation The results in this study demonstrated the associations between tiered healthcare system reform and better clinical quality performance and improved treatment cost-saving. Developing methods to promote the policy and increase implementation are also important aspects of healthcare reform.

PERC solar cell passivated on the backside with AlOx and SiNx was introduced to construct the perovskite/silicon four-terminal tandem solar cell, because of its outstanding spectral response at the long wavelength region and much lower cost than SHJ and IBC. Different from the vast majority of the related reports, which were focused on the improvement of perovskite top cell, the silicon bottom cell was optimized here to promote the tandem efficiency. The central wavelength of antireflection was adjusted to further reduce the reflectance and enhance the spectral response of PERC cell in long wavelengths, in order to make the most of long-wavelength light transmitted through the perovskite top cell. Along with the increase of central wavelength, the external quantum efficiency of PERC cell at near-infrared wavelengths increases resulting in better short circuit current density and photoelectric conversion efficiency when filtered by the perovskite cell. A tandem efficiency gain of 0.07% (abs.) has been achieved. This report provides a facile way to improve the efficiency of perovskite/silicon four-terminal tandem solar cell based on the optimization of long-wavelength spectral response.

This work discusses how the behaviour of the fill factor (FF) of devices calculated from current-voltage (I-V) measurements at different light intensities can be used as a basis to assess the trap density of methylammonium lead triiodide (MAPbI₃) solar cells. Solar cells with different trap densities are prepared using varying molar ratios of methylammonium iodide (MAI) and lead iodide (PbI₂) precursors. Excess MAI in the precursor solution yields more traps/defects in perovskite films and when the trap density increases, trap-filling is the dominant loss mechanism, which results in a low FF in perovskite solar cells with excess MAI; this is especially the case at low light intensities. The FF of perovskite solar cells with excess MAI also shows a non-monotonic dependence on light intensity: the FF first increases, followed by a decrease with increasing light intensity. This non-monotonic dependence of the FF on light intensity suggests that both trap-filling and bimolecular recombination are involved in the determination of the FF in perovskite solar cells in cases where a high density of traps exists. Furthermore, we also observed that a stoichiometric precursor solution could lead to a monotonic light intensity-dependence for the FF in perovskite solar cells: the FF continuously decreases as the light intensity is increased from 1.7 to 100 mW cm⁻². This monotonic dependence of the FF on light intensity implies that bimolecular recombination is the main reason for the loss in FF in perovskite solar cells when a low density of trap states exists. In addition, the peak light intensity (Ppeak), at which the FF shows the highest value, would shift to a smaller value when the amount of excess MAI in the precursor solution is decreased and it approaches the stoichiometric ratio of one. These results suggest that by looking at how the FF varies with light intensity we can deduce the contribution of traps in the performance of perovskite solar cells. This will help tremendously in focusing on areas for improvement for such solar cells. Ministry of Education (MOE) Nanyang Technological University Y. M. L. acknowledges financial support from grants from Innovation Fund Denmark (ALTCELL) and Ministry of Education, Singapore, Tier 1 Funding (RG105/18). We would like to acknowledge the Facility for Analysis, Characterization, Testing and Simulation (FACTS), Nanyang Technological University, Singapore, for use of their electron microscopy, Auger Electron Spectroscopy and XRD facilities.

in order to study the influence of ground fissures on the construction of expressway, a ground fissure (F1) with a strike of NE20∼45° and length of 120km in Yunnan Province is selected as the research object. The FLAC3D numerical software is used to study the characteristics of displacement and stress. The results show that: (1) under normal fault activity, vertical displacement mainly develops hanging wall. (2) The overall variation law of the surface subsidence curve presents an “s“ type distribution. (3) The stress of the two plates changes with the fracture activity, which is manifested in the stress increasing area in the footwall and the stress decreasing area in the hanging wall.

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.

At fusion plasma electron temperature and number density regimes of 1 × 103–1 × 107 K and 1 × 1028–1 × 1031/m3, respectively, the excited states and radiative transition of hydrogen-like ions in fusion plasmas are studied. The results show that quantum plasma model is more suitable to describe the fusion plasma than the Debye screening model. Relativistic correction to bound-state energies of the low-Z hydrogen-like ions is so small that it can be ignored. The transition probability decreases with plasma density, but the transition probabilities have the same order of magnitude in the same number density regime.

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.

From eastern to western areas, per- and polyfluoroalkyl substances (PFASs) were detected at substantial levels in the outdoor dust across mainland China. Urban samples generally showed higher levels compared with those of rural samples. Compared with neutral PFASs, ionizable PFASs (C4-C12 perfluoroalkyl carboxylic acids and C4/C8 perfluoroalkyl sulfonic acids) were more abundant, with the highest total concentration up to 1.6 × 10(2) ng/g and perfluorooctanoic acid (PFOA) being a predominant analogue. Fluorotelomer alcohols (FTOHs) and polyfluoroalkyl phosphoric acid diesters (DiPAPs) were both detected in most samples with total concentrations of 0.12-32 and 0.030-20 ng/g, respectively. Perfluorooctane sulfonamidoethanols/sulfonamides (FOSE/As) were detected at low frequencies (

Background According to the theory of compensating differentials, caregivers with high levels of intrinsic motivation should exhibit a higher-than-average satisfaction with their pay. Whereas studies conducted in Western countries have provided empirical evidence for the theory of compensating differentials in various care settings, few studies have been conducted in China that focus on caregivers employed in residential homes for the elderly (RHE). The sociodemographic characteristics of caregivers in China different significantly from their counterparts in Western countries. Purpose This study was developed to analyze the mediating role of job burnout to assess the influence of intrinsic motivation on pay satisfaction among caregivers in RHE. Methods Structural equation modeling was used to examine the influences of intrinsic motivation on pay satisfaction in a sample of 1,212 caregivers employed in RHE in China by analyzing the mediating role of job burnout. Results Intrinsic motivation was found to relate positively to pay satisfaction (β = .11, p < .05). Negative relationships were identified between intrinsic motivation and job burnout (β = −.46, p < .01) and between job burnout and pay satisfaction (β = −.13, p < .01). Job burnout was found to have a significant mediating effect on the relationship between intrinsic motivation and pay satisfaction (β = .06, p < .01). Conclusions/Implications for Practice A significant relationship was found between intrinsic motivation and pay satisfaction, with job burnout playing a mediating role in caregivers employed in RHE in China. This research has profound implications for nursing education, practice, and research. First, greater efforts should be focused on instilling nursing values in nursing students to foster intrinsic motivation. Second, nonpecuniary rewards may be offered to caregivers to acknowledge the values of care work and strengthen intrinsic motivation. Third, a supportive working climate should be fostered to reduce job burnout. Fourth, caregivers should be informed of their rights to decent pay and their right to bargain collectively through unions. Fifth, appropriate public policies should be implemented to provide pay for caregivers at levels that recognize and appreciate their intrinsic motivation.

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.

We propose a method that obtains a discriminative visual dictionary and a nonlinear classifier for visual tracking tasks in a sparse coding manner based on the globally linear approximation for a nonlinear learning theory. Traditional discriminative tracking methods based on sparse representation learn a dictionary in an unsupervised way and then train a classifier, which may not generate both descriptive and discriminative models for targets by treating dictionary learning and classifier learning separately. In contrast, the proposed tracking approach can construct a dictionary that fully reflects the intrinsic manifold structure of visual data and introduces more discriminative ability in a unified learning framework. Finally, an iterative optimization approach, which computes the optimal dictionary, the associated sparse coding, and a classifier, is introduced. Experiments on two benchmarks show that our tracker achieves a better performance compared with some popular tracking algorithms.

The ultrasonic phased array total focusing method (TFM) has the advantages of full-range dynamic focusing and high imaging resolution, but the problem of long imaging time limits its practically industrial applications. To reduce the imaging calculation demand of TFM, the locations of active array elements in the sparse array are optimized by combining almost different sets with the genetic algorithm (ADSGA), and corrected based on the consistency of the effective aperture with the equivalent point diffusion function. At the same time, to further increase the imaging efficiency, a sparse-TFM image with lower resolution is obtained by reducing the number of focus points and then interpolated by the new edge-directed interpolation algorithm (NEDI) to obtain a high quality sparse-TFM image. Compared with TFM, the experimental results show that the quantitative accuracy of the proposed method is only decreased by 1.09% when the number of sparse transmitting elements reaches 8 for a 32-element transducer, and the imaging speed is improved by about 16 times with the same final pixel resolution.

We describe a new approach for preparing organic-inorganic perovskite solar cells for electron beam-induced current (EBIC) measurements in plan-view geometry. This method substantially reduces sample preparation artefacts, provides good electrical contact and keeps the preparation steps as close as possible to those for real devices. Our EBIC images were acquired simultaneously with annular dark-field scanning transmission electron microscopy images using a home-made highly sensitive EBIC amplifier. High-angle annular dark-field images and energy dispersive X-ray maps were recorded from the same area immediately afterwards. This allowed the EBIC contrast to be correlated with regions containing N and a deficiency of O. The EBIC contrast was also found to be similar to secondary electron contrast recorded with a scanning electron microscope. By identifying the generation and absorption electron processes, we determine that EBIC cannot be separated from the secondary electron and absorbed currents. This means that careful analysis needs to be performed before conclusions can be made on the origin of the current measured across p-n or p-i-n junctions. Nanyang Technological University We are grateful to Thomas Duden for the fabrication and operation of the amplifier during the EBIC experiments. M.D. acknowledges fi- nancial support from Nanyang Technological University start-up grant M4081924

Background Despite decades of study, debates exist surrounding the relationship between education and functional health status transition among elderly populations. This study aims to add evidence to the debates using China as a case study. Specifically, this study analysed the association of education with functional health status transition and then the mechanism behind that association using the budget constraint relax hypothesis and the efficiency improvement hypothesis among elderly population in China. Methods Based on data from the Chinese Longitudinal Healthy Longevity Surveys from 2008 and 2011, this study focussed on adults aged 65 years and above, with a final sample size of 12,112. A generalised structural equation model was used to analyse the relationship between education and functional health status transition and the mechanism behind that association. Results During the three examined years, among elderly adults who were nondisabled at baseline, 53.1% stayed nondisabled, 14.6% became disabled, and 32.3% died; among those disabled in 2008, 8.1% recovered, 21.6% stayed disabled, and 70.3% died. Compared with older adults without any education, those who had attended primary schools had both lower mortality and disability, whereas those who had attended high schools and above only had a lower mortality rate. The budget constraint relax hypothesis and the efficiency improvement hypothesis explained the majority of the relationship between education and transition from non-disability to death, but hardly explained the transition from non-disability to disability. Furthermore, once a person was disabled, education had no significant relationship with functional ability recovery or mortality. Conclusions Attending primary school seems to provide the highest benefit to functional health status transition among older and nondisabled persons in China. Those who attended high schools and above are expected to live a longer life with disability. The mechanism between education and the onset of disability needs more discussion.

Background Depressive symptom disparity between urban and rural older adults is an important public health issue in China. Social support is considered as an effective way to alleviate depression of older adults. This study aimed to investigate the extent to which social support could explain the depressive symptom disparity between urban and rural older adults in China. Methods This study used data drawn from the 2011 China Health and Retirement Longitudinal Study with 6,772 observations. Multiple data analysis strategies were adopted, including descriptive analyses, bivariate analyses, regression analyses and decomposition analyses. Results There were significant depressive symptom disparities between urban and rural older adults in China. Social support had significant association with depressive symptom of older adults while adjusting for covariates. About 25%–28% of the depressive symptom disparities could be attributed to urban–rural gaps in social support, in which community support contributed 21%–25%. Educational level and physical health status also contributed to the disparities. Limitation This study only established correlations between social support and depressive symptom disparity rather than casual relationships; and the self-reported measurement of depressive symptom and the unobservable cultural factors might cause limitations. Conclusions The urban–rural gap in social support, especially community support was a prime explanation for depressive symptom disparities between urban and rural older adults in China. To reduce the depressive symptom disparities, effective community construction in rural China should be put into place, including improving the infrastructure construction, strengthening the role of social organizations, and encouraging community interpersonal interactions for older adults.

Hybrid inorganic-organic perovskites have recently attracted much interest because of both rich fundamental sciences and potential applications such as the primary energy-harvesting material in solar cells. However, an understanding of electronic and optical properties, particularly the complex dielectric function, of these materials is still lacking. Here, we report on the electronic and optical properties of selective perovskites using temperature-dependent spectroscopic ellipsometry, x-ray absorption spectroscopy supported by first-principles calculations. Surprisingly, the perovskite FA0.85Cs0.15PbI2.9Br0.1 has a very high density of low-energy excitons that increases with increasing temperature even at room temperature, which is not seen in any other material. This is found to be due to the strong, unscreened electron-electron and partially screened electron-hole interactions, which then tightly connect low- and high-energy bands caused by doping. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) Published version

Sparse coding methods have achieved great success in visual tracking, and we present a strong classifier and structural local sparse descriptors for robust visual tracking. Since the summary features considering the sparse codes are sensitive to occlusion and other interfering factors, we extract local sparse descriptors from a fraction of all patches by performing a pooling operation. The collection of local sparse descriptors is combined into a boosting-based strong classifier for robust visual tracking using a discriminative appearance model. Furthermore, a structural reconstruction error based weight computation method is proposed to adjust the classification score of each candidate for more precise tracking results. To handle appearance changes during tracking, we present an occlusion-aware template update scheme. Comprehensive experimental comparisons with the state-of-the-art algorithms demonstrated the better performance of the proposed method.

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.

The spray characteristics of diesohol fuel have a direct effect on the thermal efficiency and combustion emissions performance of diesel engines. In this research, we investigated the spray characteristics of diesohol fuel under different fuel injection pressures (Pinj) in a high-pressure common-rail injection system and at various spray ambient pressures (Pamb) in a constant-volume pressure vessel by using high-speed photography technology. The research results support the concept of adding a certain percentage of ethanol to diesel, creating diesohol fuel, which can reduce the environmental impacts of vehicle emissions. Experiments on the spray characteristics were performed and the results suggested that the addition of ethanol has no significant effect on the spray tip penetration, spray cone angle, and spray tip speed. However, atomization conditions such as injection pressure and ambient pressure have a significant impact on the spray characteristics of the blended fuel.

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.

Considering the quantum effects of diffraction and the collective screening effects, the potential of test charge in semiclassical plasmas is derived. It is generalized exponential screened Coulomb potential. Using the Ritz variational method incorporating this potential, the effects of semiclassical plasma on the energy levels and radiative transitions are investigated systematically, taking highly charged H-like ion as an example. The Debye plasma model is also employed for comparison purposes. Comparisons and analysis are made between these two sets of results and the differences are discussed.

Glypican-3 (GPC3), the cellular membrane proteoglycan, has been established as a tumor biomarker for early diagnosis of hepatocellular carcinoma (HCC). GPC3 is highly expressed in more than 70% HCC tissues detected by antibody-based histopathological systems. Recently, aptamers, a short single-strand DNA or RNA generated from systematic evolution of ligands by exponential enrichment (SELEX), were reported as potential alternatives in tumor-targeted imaging and diagnosis. In this study, a total of 19 GPC3-bound aptamers were successfully screened by capillary electrophoresis (CE)-SELEX technology. After truncated, AP613-1 was confirmed to specifically target GPC3 with a dissociation constant (KD) of 59.85 nM. When modified with a phosphorothioate linkage, APS613-1 targeted GPC3 with a KD of 15.48 nM and could be used as a specific probe in living Huh7 and PLC/PRF/5 imaging, GPC3-positive cell lines, but not in L02 or A549, two GPC3-negative cell lines. More importantly, Alexa Fluor 750-conjugated APS613-1 could be used as a fluorescent probe to subcutaneous HCC imaging in xenograft nude mice. Our results indicated that modified AP613-1, especially APS613-1, was a potential agent in GPC3-positive tumor imaging for HCC early diagnosis. Keywords: GPC3, CE-SELEX, ssDNA aptamer, flow cytometry, cell imaging

In this paper, we present an approach to recognize the Machine-printed Mongolian characters by CNN (convolutional neural network). Firstly, a training set of traditional Mongolian characters is collected in advance. There are 85 categories in all and each category is trained and recognized by the CNN. And then, we set a CNN with seven layers. There are three convolution layers, two subsampling layers, one full connected layer and an output layer in the CNN. The experimental results show that the CNN is superior to the BP neural networks for the Machine-printed traditional Mongolian characters. In the BP neural network, the average accuracy is 88.34%. The proposed CNN based method can improve the average accuracy from 88.34% to 99.39% and the improvement rate can be attained to 12.51%.

This article explores the effects of SiO2/Al2O3 ratios (S/A) on sintering characteristics and provides guidance for alleviating ash depositions in a large-scale circulation fluidized bed. Five synthetic coal ash (SCA) samples with different S/As were treated in a muffle furnace for 12 h at different temperatures (from 773 K to 1373 K, in 100 K intervals). The morphological and chemical results of the volume shrinkage ratio (VSR), thermal deformation analysis by dilatometer (DIL), scanning electron microscope (SEM), X-ray photoelectron spectrometer (XPS), and X-ray diffraction (XRD) were combined to describe the sintering characteristics of different samples. The results showed that the sintering procedure mainly occurred in the third sintering stage when the temperature was over 1273 K, accompanied with significant decreases in the VSR curve. Excess SiO2 (S/A = 4.5) resulted in a porous structure while excess Al2O3 (S/A = 0.5) brought out large aggregations. The other three samples (S/A = 1.5, 2.5, 3.5) are made up of an amorphous compacted structure and are composed of low fusion temperature materials (e.g., augite and wadsleysite.). Sintering temperatures first dramatically decrease to a low level and then gradually rise to a high level as S/A increases, suggesting that Al2O3-enriched additives are more effective than SiO2enriched additives in alleviating depositions.

Surface roughness of a sample has a great effect on the calculated grain size when measurements are based on ultrasonic attenuation. Combining modified transmission and reflection coefficients at the rough interface with a Multi-Gaussian beam model of the transducer, a comprehensive correction scheme for the attenuation coefficient is developed. An approximate inverse model of the calculated attenuation, based on Weaver's diffuse scattering theory, is established to evaluate grain size in polycrystals. The experimental results showed that for samples with varying surface roughness and matching microstructures, the fluctuation of evaluated average grain size was ±1.17μm. For polished samples with different microstructures, the relative errors to optical microscopy were no more than ±3.61%. The presented method provides an effective nondestructive tool for evaluating the grain size in metals with rough surfaces.

Hydraulic turbine runner has a complex structure, and traditional location methods can't meet its requirement. This paper describes a source location of cracks in turbine blades by combining kernel independent component analysis (KICA) with wavelet neural network (WNN). The research shows that the location accuracy of WNN combined with KICA feature extraction is the best comparing with the results of WNN and back propagation neural network (BPNN). The method decreases the dimension of input parameters and improves the accuracy of location as well.

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.