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The loess hilly area consists of a slope–gully system, which promotes erosion; as such. it is one of the most intensely eroded areas in the world. The construction of check dams can effectively control water and soil loss of slope gullies. However, existing studies focus on the benefits of intercepting runoff and sediments at dam sites, while ignoring the change law of hydrological processes with respect to progressing dam land sedimentation. Moreover, past studies focus on the "runoff–sediment" or "flood–sediment" relationships, but rarely consider the "hydrodynamics–runoff" and "hydrodynamics–sediment" dynamics. Therefore, in this study, we developed five physical models of slope–gully systems for dam land sedimentation depths of 0, 1, 2, 3, and 4 m, in order to explore the effects of sedimentation on runoff–sediment–hydrodynamic processes. The runoff and sediment yield of the slope–gully system decreased with increasing siltation depth. The spatial and temporal distributions of the hydrodynamic parameters were different. The Reynolds number (Re), runoff energy consumption (ΔE), and runoff power (P) increased with rainfall time, whereas runoff shear stress (τ) and Froude number (Fr) did not show a significant trend over time. Re and ΔE could better describe the runoff process of the slope–gully system, while P and ΔE could better simulate the sedimentation process. Notably, our study can provide a scientific basis for establishing effective erosion prediction models to estimate the water erosion process of slope–gully systems. [ABSTRACT FROM AUTHOR]

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In the two-step preparation of perovskite solar cells, the ambient temperature is the main factor affecting the performance of the cells and controlling the crystallization of perovskite films. In this paper, we demonstrate the importance of resting temperature in the preparation of perovskite solar cells based on the morphology of PbI2 film and perovskite film. The ambient temperature around the PbI2 film directly influences its morphology after resting, and then affects the morphology of the annealed perovskite film. The experimental results show that the optimum ambient temperature for resting PbI2 is 28 °C at which solar cell conversion efficiency is improved to 22.2%. This study is of great significance to the preparation of high-performance PVSCs. [ABSTRACT FROM AUTHOR]

A sensitive element for realizing the pressure sensing at high temperature is experimentally prepared using the microelectromechanical systems (MEMS) fabrication technology and consists of a 50-μm-thick, 1400-μm-wide square multilayer component membrane (including silicon, silicon dioxide, and silicon nitride) and a monolayer graphene with meander pattern. The prepared sample is characterized and analyzed using various techniques including atomic force microscopy, Raman spectroscopy, and the finite element method. The strain distribution in the pressed membrane is simulated by the finite element method. The pressure sensing based on the monolayer graphene with meander pattern can be realized according to the strain distribution and the high-temperature measurements for the sensitive element. Accordingly, a new pressure sensor based on the sensitive element is proposed for exploring the sensing performance depending on the piezoresistive property of monolayer graphene at high temperature. The sensing performance can be obtained by the theoretical analysis for electromechanical measurements at high temperature for the sensitive element. The results demonstrate that the performances of the sensor are excellent at high temperature. In particular, the sensitivity is much higher than that of previous high-temperature MEMS pressure sensors. Our results can provide insights for realizing the high-temperature applications of graphene in electronic devices. [ABSTRACT FROM AUTHOR]

Soil organic carbon (SOC) plays an essential role in the carbon cycle and global warming mitigation, and it varies spatially in relation to other soil and environmental properties. But the national distributions and the impact mechanisms of SOC remain debated in China. Therefore, how soil texture and climate factors affect the SOC content and the regional differences in SOC content were explored by analyzing 7857 surface soil samples with different land-use. The results showed that the SOC content in China, with a mean value of 11.20 g·kg−1, increased gradually from north to south. The SOC content of arable land in each geographical area was lower than in grassland and forest-land. Although temperature also played a specific role in the SOC content, precipitation was the most critical climate factor. The SOC content was positively correlated with the silt and clay content. The lower the temperature, the greater the effect of environmental factors on SOC. In contrast, the higher the temperature, the more significant impact of soil texture on SOC. The regional difference in SOC highlights the importance of soil responses to climate change. Temperature and soil texture should be explicitly considered when predicting potential future carbon cycle and sequestration. [ABSTRACT FROM AUTHOR]

Ferroelectric hafnium oxide (HfO2) thin film has been widely studied as a promising material candidate for microelectronic devices. In this paper, HfO2/Hf/HfO2 stacked films were deposited by reactive magnetron sputtering to investigate the effects of metal Hf on the phase transition and electric properties. An interesting phenomenon is that HfO2 film inserted with a thin layer of metal Hf exhibits ferroelectricity after high-field cycling (wake-up). The generation of ferroelectricity is due to a region in HfO2 film with a gradient distribution of oxygen vacancies resulting in the formation of orthorhombic HfO2, which is caused by the oxidation of metal Hf in HfO2 film. Inserted with 0.2-nm-thick metal Hf layer, the stacked film shows the coercive field of 3.4 MV/cm and remanent polarization of 4.2 μC/cm2, respectively. An increase in the Hf layer thickness from 0.2 to 1.5 nm causes the leakage current density of the stacked film increasing from 8.2 × 10–6 to 6.2 × 10–4 A/cm2. The results provide a strong evidence for the important role of inhomogeneous oxygen vacancies played in introduction of the ferroelectricity of HfO2 film. [ABSTRACT FROM AUTHOR]

Purpose: As an epigenetic regulation mechanism after transcription, RNA modification is installed by endogenous "writer" enzymes and is widely involved in a variety of physiological processes, including cancer progression. This study explored the RNA modification patterns of cervical cancer to clarify overall effect of RNA modification on tumor microenvironment (TME) characteristics and immune/targeted therapy. Methods: 26 RNA modification "writers" were clustered, and the RNA modification patterns and TME characteristics of cervical cancer patients in TCGA were systematically evaluated. Based on differentially expressed genes (DEGs) between different RNA modification patterns, an RNA modification "writer" score (WM score) system was developed to assess the RNA modification of a single sample. Results: Two different RNA modification patterns of cervical cancer were identified, and these patterns were significantly related to the prognosis and TME infiltration characteristics of patients. WM score was an independent risk factor for the prognosis of cervical cancer. High WM score was characterized by poor prognosis, low immune infiltration and low tumor mutation burden (TMB), while low-WM score was related to relatively long overall survival (OS), more immune components in TME and increased TMB. In addition, the low-WM score group was expected to be more sensitive to programmed cell death protein 1 (PD-1) therapy and showed lower predicted IC50 of chemotherapy drugs paclitaxel and cisplatin treatment. Conclusions: This study identified and characterized RNA modification patterns, and clarified potential relationship between RNA modification patterns and immune infiltration characteristics and immunotherapy of cervical cancer, offering a new evaluation scheme for treatment of cervical cancer patients. [ABSTRACT FROM AUTHOR]

In this paper, a wafer-level package with hermetic sealing by low-temperature Cu/Sn transient liquid phase (TLP) bonding for a micro-electromechanical system was introduced. A Cu bump with a Sn cap and sealing ring were fabricated simultaneously by electroplating. The model of Cu/Sn TLP bonding was established and the thicknesses of Cu and Sn were optimized after a series of bonding experiments. Cu/Sn wafer-level bonding was undertaken at 260°C for 30 min under a vacuum condition. An average shear strength of 50.36 MPa and a fine leak rate of 1.9 × 10 atm cc/s were achieved. Scanning electron microscope photos of the Cu/Sn/Cu interlayers were presented, and energy dispersive x-ray analysis was conducted simultaneously. The results showed that the Sn was completely consumed to form the stable intermetallic compound CuSn. An aging test of 200 h at 200°C was conducted to test the performance of the hermetic sealing, while the results of shear strength, fine leak rate and bonding interface were also set out. [ABSTRACT FROM AUTHOR]

In this study, well-crystallized mesoporous anatase TiO spheres (TiO-MS) were prepared via a simple sol-gel process followed by subsequent hydrothermal treatment and then used as photoelectrode for quantum-dot-sensitized solar cell (QDSC) application. The mesoporous structure exhibits efficient QD loading and good light-scattering properties for light harvesting. In the meantime, both surface photovoltage technique based on lock-in amplifier and transient photovoltage measurement reveal that the QDs-sensitized mesoporous TiO sphere photoelectrode is conducive to promote the separation of photo-induced charges and reduce the charge recombination owing to the efficient charge transfer. As a result, the QDSCs based on mesoporous TiO spheres photoelectrode shows a power conversion efficiency of 1.34 %, which is significantly higher than that derived from P25 nanoparticle electrode. The relation between the performance of QDSCs and their photovoltage characterization was also discussed. [ABSTRACT FROM AUTHOR]

Effective appearance models are one critical factor for robust object tracking. In this paper, we introduce foreground feature saliency concept into the background modelling, and put forward a novel foreground saliency-based background-weighted histogram scheme (FSBWH) for target representation and tracking, which exploits salient features from both foreground and background. We think that background and foreground salient features are both crucial for target representation and tracking. Experimental results show that the proposed FSBWH scheme can improve the robustness and performance of tracker significantly especially in complex occlusions and similar background scenes. [ABSTRACT FROM AUTHOR]

Purpose: Amniotic fluid mesenchymal stem cells (AF-MSCs) are promising candidates for cell-based therapy. This review presents a comprehensive overview of the features and therapeutic applications of these cells. Methods: This is a literature review combined with experience of practice. Conclusion: Although the long-term risks of AF-MSCs require further investigation, these cells are increasing in popularity in the fields of regenerative medicine and targeting therapy because of their unique properties. [ABSTRACT FROM AUTHOR]

Motivated by a phenomenon in an experiment conducted in the Northwestern Pacific indicating that the energy of the received signal around the sound channel axis is much greater than that at shallower depths, we study sound propagation from the transitional area (shelfbreak) to deep water. Numerical simulations with different source depths are first performed, from which we reach the following conclusions. When the source is located near the sea surface, sound will be strongly attenuated by bottom losses in a range-independent oceanic environment, whereas it can propagate to a very long range because of the continental slope. When the source is mounted on the bottom in shallow water, acoustic energy will be trapped near the sound channel axis, and it converges more evidently than the case where the source is located near the sea surface. Then, numerical simulations with different source ranges are performed. By comparing the relative energy level in the vertical direction between the numerical simulations and the experimental data, the range of the air-gun source can be approximated. [ABSTRACT FROM AUTHOR]

By using the surface photovoltage (SPV) technique based on a lock-in amplifier, surface states located 3.1 eV below the conduction band of TiO have been detected in TiO nanotube arrays prepared by anodization of titanium foil in fluoride-based ethylene glycol solution. The photo-induced charge transportation behavior of TiO nanotube arrays was also studied by qualitatively analyzing their SPV phase spectra measured under different external bias. When a negative bias was applied, carriers excited from surface states have the same transportation properties as those excited from the valence band; in contrast, when a positive bias was applied, these two kinds of photo-excited carriers exhibit different transportation behavior. [ABSTRACT FROM AUTHOR]

Highly photocatalytically active cobalt-doped ZnO (ZnO:Co) nanorods have been prepared by a facile hydrothermal process. X-ray diffraction, X-ray photoelectron spectroscopy, Raman scattering and UV-vis diffuse reflectance spectroscopy confirmed that the dopant ions substitute for some of the lattice zinc ions, and furthermore, that Co and Co ions coexist. The as-prepared ZnO:Co samples have an extended light absorption range compared with pure ZnO and showed highly efficient photocatalytic activity, only requiring 60 min to decompose ∼93% of alizarin red dye under visible light irradiation ( λ > 420 nm). The photophysical mechanism of the visible photocatalytic activity was investigated with the help of surface photovoltage spectroscopy. The results indicated that a strong electronic interaction between the Co and ZnO was present, and that the incorporation of Co promoted the charge separation and enhanced the charge transfer ability and, at the same time, effectively inhibited the recombination of photogenerated charge carriers in ZnO, resulting in high visible light photocatalytic activity. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

facile and reproducible method has been developed for the synthesis of ordered anatase Mn-TiO nanospheres with controllable sizes in the range 200-300 nm by simply varying the amount of manganese(II) chloride added. The samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and transmission electron microscope (TEM) measurements, and it was found that the manganese exists in multivalent forms (Mn/ Mn) and substitutes for some of the Ti in the anatase TiO lattice. The presence of Mn significantly influences the morphology and high-temperature stability of TiO, and extends its light absorption range. Surface photovoltage and photocurrent measurements revealed that an electronic interaction between the Mn and TiO was present, in which Mn served as an electron acceptor and effectively inhibited the charge recombination in TiO; this is thought to be responsible for the highly efficient photocatalytic activity of the material in the degradation of rhodamine B (RhB) under visible-light irradiation ( λ > 420 nm). [ABSTRACT FROM AUTHOR]

The synthesis of graphene-semiconductor nanocomposites has attracted increasing attention due to their interesting optoelectronic properties. However the synthesis of such nanocomposites, with decorated particles well dispersed on graphene, is still a great challenge. This work reports a facile, one-step, solvothermal method for the synthesis of graphene-CdS and graphene-ZnS quantum dot nanocomposites directly from graphene oxide, with CdS and ZnS very well dispersed on the graphene nanosheets. Photoluminescence measurements showed that the integration of CdS and ZnS with graphene significantly decreases their photoluminescence. Transient photovoltage studies revealed that the graphene-CdS nanocomposite exhibits a very unexpected strong positive photovoltaic response, while separate samples of graphene and CdS quantum dots (QDs) of a similar size do not show any photovoltaic response. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

We propose a variational algorithm to jointly estimate the shape, albedo, and light configuration of a Lambertian scene from a collection of images taken from different vantage points. Our work can be thought of as extending classical multi-view stereo to cases where point correspondence cannot be established, or extending classical shape from shading to the case of multiple views with unknown light sources. We show that a first naive formalization of this problem yields algorithms that are numerically unstable, no matter how close the initialization is to the true geometry. We then propose a computational scheme to overcome this problem, resulting in provably stable algorithms that converge to (local) minima of the cost functional. We develop a new model that explicitly enforces positivity in the light sources with the assumption that the object is Lambertian and its albedo is piecewise constant and show that the new model significantly improves the accuracy and robustness relative to existing approaches. [ABSTRACT FROM AUTHOR]

Identifies the self-excited vibration of rolling mill drive trains in rolling slippage in China. Number of classical engineering problems associated with torsional vibration; Cause of the breakage of train elements; Factors influencing torque amplification.

Despite great efforts dedicated to enhance power conversion efficiency (PCE) of quantum dot-sensitized solar cells (QDSSCs) in the past two decades, the efficiency of QDSSCs is still far behind its theoretical value. The present approaches for improving PCE are mainly focused on tailoring the bandgap of QDs to broadening light-harvesting and optimizing interfaces of component parts. Herein, a new solar cell architecture is proposed by integrating concentrating solar cell (CPV) concept into QDSSCs with double photoanode design. The Cu2S mesh is used as a counter electrode and sandwiched between two photoanodes. This designed battery structure can increase the PCE by 260% compared with a single photoanode. With the most extensively used CdS/CdSe QD sensitizers, a champion PCE of 8.28% (Voc = 0.629 V, Jsc = 32.247 mA cm−2) was achieved. This is mainly due to the increase in Jsc due to the double photoanode design and adoption of the CPV concept. In addition, another reason is that concentrated sunshine illumination induced a photothermal effect, accelerating the preceding chemical reactions associated with the conversion of polysulfide species. The cell fabrication and design reported here provides a new insight for further development of QDSSCs. [ABSTRACT FROM AUTHOR]