Fe(III) grafted MoO3 nanorods for effective electrocatalytic fixation of atmospheric N2 to NH3

Electrocatalytic nitrogen reduction reaction (ENRR) offers a carbon-neutral process to fix nitrogen into ammonia, but its feasibility depends on the development of highly efficient electrocatalysts. Herein, we report that Fe ion grafted on MoO₃ nanorods synthesized by an impregnation technique can efficiently enhance the electron harvesting ability and the selectivity of H⁺ during the NRR process in neutral electrolyte. In 0.1 M Na₂SO₄ solution, the electrocatalyst exhibited a remarkable NRR activity with an NH₃ yield of 9.66 μg h^?1 mg^?1_cat and a Faradaic efficiency (FE) of 13.1%, far outperforming the ungrafted MnO₃. Density functional theory calculations revealed that the Fe sites are major activation centers along the alternating pathway.     

滇黔相邻区二叠系宣威组富稀土黏土岩综合研究进展

在滇黔相邻区峨眉山玄武岩之上，二叠系宣威组下部广泛分布一套富稀土黏土岩。作为一种新类型的潜在稀土资源，诸多学者对其进行了研究，包括成矿条件、赋存状态，富集规律、综合利用方式等多个方面都有了较大的进展。该类型稀土具有非常大的资源潜力，区域连续性好、集中程度高，富含高价值的稀土元素镨、钕、铽、镝，经济价值和开发利用潜力巨大。本文全面总结了宣威组稀土目前的研究进展和存在的关键问题，提出了下一步研究方向。当前对于宣威组富稀土黏土岩中稀土元素的富集机理尚未明确，进一步开展成矿理论研究是找矿突破的关键；赋存状态的研究亟待突破，对该新类型稀土的综合利用技术突破，后期绿色勘查开发具有重要的意义；综合利用方面，经济可行的绿色选冶技术、伴生的铝、铌、锆、镓、钛等有价元素的综合回收、尾矿的资源化消纳等方面是下一步的主攻方向。      

Sealing behaviour of glass-based composites for oxygen transport membranes

In this study, seven different filler materials in different proportions were added to a Ba-Ca-Si glass matrix “H” to investigate new sealant with higher thermal expansion coefficient (CTE) value and good sealing performance for application in oxygen transport membrane (OTM). SrTi_0.75Fe_0.25O_3-δ (STF25) was used as an OTM, and the sealing partners were ferritic steel Aluchrom and pre-oxidized Aluchrom. Compatibility tests were carried out to investigate the feasibility of the composites. Higher CTE values were found in dilatometer tests on composite samples by adding 40 wt% Ag (HAg40) and 30 wt% Ni-Cr (HNC30). Gas-tightness measurements of sandwiched samples produced appropriate helium leakage rates in the range of 10^?6 mbar·l·s^?1. Sealing behaviour of sealants HAg40 and HNC30 were investigated by joining STF25 and as-delivered/pre-oxidized Aluchrom together. Scanning electron microscopy (SEM) on cross-sections of the joints revealed a homogeneous microstructure and good adherence of the glass sealants to support metals and STF25.     

Application of web embedded system and machine learning in english corpus vocabulary recognition

Built-in applications built on a stand-alone device, TCP / IP network and interconnected are a need for high integration with other systems. The system provided through Web services interconnects service-oriented distributed architecture. The TCP / IP network is widely employed to integrate business applications. This integration is still not provided through the embedded application. The applications connected to the Internet are an especially difficult problem in embedded systems to interpret the sensor data. Real-time sensor function generates a training/classification result for IoT application selected, customized, or data structure design. It has an integrated hardware/software system to achieve the continuous training and real-time data analysis and re-training of Machine Learning (ML) algorithm. World of English native speakers on top of all, this is the database of words that have been separated from the local and non-collection English. It also reported a variety of methods that are used in the English vocabulary recognition system. Please check the study of learners of mediation based on the part of the corpus. Students, in writing, too much-advanced technology and general vocabulary. These students, publicly their discourse in and contributed to the professional corpus of "existence" I mentioned that there is a professional writer, is better. To stimulate the different means of integration, it evaluated several network technology today, discussing the balance between the use of shared with this integration in the adaptability and built-in the field of Web network technology of today.     

Preparation and electrochemical characterization of Ti-based amorphous metallic glass with high strength

Ti-based amorphous metallic glasses have excellent mechanical, physical, and chemical properties, which is an important development direction and research hotspot of metal composite reinforcement. As a stable, simple, efficient, and large-scale preparation technology of metallic powders, the gas atomization process provides an effective way of preparing amorphous metallic glasses. In this study, the controllable fabrication of a Ti-based amorphous powder, with high efficiency, has been realized by using gas atomization. The scanning electron microscope, energy-dispersive spectrometer, and X-ray diffraction are used to analyze surface morphology, element distribution, and phase structure, respectively. A microhardness tester is used to measure the mechanical property. An electrochemical workstation is used to characterize corrosion behavior. The results show that as-prepared microparticles are more uniform and exhibit good amorphous characteristics. The mechanical test shows that the hardness of amorphous powder is significantly increased as compared with that before preparation, which has the prospect of being an important part of engineering reinforced materials. Further electrochemical measurement shows that the corrosion resistance of the as-prepared sample is also significantly improved. This study has laid a solid foundation for expanding applications of Ti-based metallic glasses, especially in heavy-duty and corrosive domains.     

High-surface-area mesoporous silica-yttria-zirconia ceramic materials prepared by coprecipitation method ― the role of silicon

A high surface area is one of desired properties for yttria-zirconia (Y₂O₃–ZrO₂) ceramic materials given their catalytic applications. The objective of this study is to develop high-surface-area Y₂O₃–ZrO₂ materials by silicon (Si) modification and investigate the role of Si. Si-modified yttrium-zirconium hydroxides were prepared via a one-step precipitation process and calcined at 800 or 950 °C to form Si-modified Y₂O₃–ZrO₂ (denoted as SiO₂–Y₂O₃–ZrO₂) materials containing 0-20 wt% Si as SiO₂. These hydroxides or materials were characterized by ²⁹Si NMR, XPS, TG-DSC, XRD, UV Raman, TEM, and N₂ physisorption measurements. Si species uniformly distributed in the hydroxides tended to be enriched on the material surface at high temperatures. These Si species dominated by the silicates blocked the migration of Y and Zr atoms, which resisted the crystallite growth of Y₂O₃–ZrO₂ components and reduced their crystallite size. Therefore, the SiO₂–Y₂O₃–ZrO₂ possessed a surface area of 59-112 m²/g after calcination at 950 °C for 9 h, which was significantly higher than that of the Y₂O₃–ZrO₂ (23 m²/g). This study may stimulate ideas for developing high-surface-area crystalline ceramic materials calcined at high temperatures.     

Adaptive GLR-, Rao- and Wald-based CFAR detectors for a subspace signal embedded in structured Gaussian interference

The problem of detecting a subspace signal embedded in subspace Gaussian interference and thermal noise is studied in this paper. In this problem, both the signal-independent and signal-dependent interferences are assumed to be present, therefore the overall interference subspace covers the signal subspace. The approach of this paper extends previous works involving either of those two kinds of interferences. A set of secondary data containing only interference plus noise is employed to estimate the interference covariance matrix and the noise power. Three new detectors are designed via the generalized likelihood ratio (GLR), Rao and Wald tests, respectively. Their probabilities of false alarms (PFAs) and detections are analytically derived. The PFAs show that the new detectors have the constant false alarm rate (CFAR) property against the interference and noise. Numerical results show that the new detectors outperform their counterparts for the studied problem. Furthermore, the new detectors are less sensitive to the secondary data size and to the mismatched subspace signal than some other detectors, such as the GLR detector (GLRD), the adaptive matched filter (AMF), the adaptive subspace detector (ASD), etc.     

Effect of strontium substitution on the structure and dielectric properties of unfilled tungsten bronze Ba4-xSrxSmFe0.5Nb9.5O30 ceramics

The effects of Sr²⁺ substitution for Ba²⁺ on phase structure, microstructure, dielectric and electric properties for Ba_4-xSr_xSmFe_0.5Nb_9.5O₃₀ (x = 0, 1, 2, 3 and 4) ceramics were systematically researched. X-ray diffraction patterns show that Ba_4-xSr_xSmFe_0.5Nb_9.5O₃₀ (x = 0, 1, 2 and 3) ceramics are tetragonal tungsten bronze compound with a space group of P4bm, while the sample for x = 4 is an orthorhombic structure compound. The result can be corroborated by the analysis of Raman spectroscopy. As the Sr²⁺ contents increase from 0 to 3, the full width at half maximum of Raman lines of all samples increase gradually, indicating that the degree of lattice distortion increase. All tetragonal tungsten bronze ceramics exhibited a broad permittivity peaks, accompanied by frequency dispersion, indicating all samples are relaxor. The electrical properties of BSSFN ceramics were further studied by complex impedance spectroscopy. XPS spectrum shows that Fe²⁺ and Fe³⁺ coexist in Ba_4-xSr_xSmFe_0.5Nb_9.5O₃₀ ceramics, and their proportion varies with the concentration of Sr²⁺.     

芽孢杆菌Bacillus sp.dwc-2对模拟地下水中U(Ⅵ)的还原行为研究

在厌氧条件下研究了西南地区一种典型土壤微生物芽孢杆菌Bacillus sp.dwc-2对模拟地下水中U(Ⅵ)的还原行为，重点考察了时间、无机阴离子、腐殖酸（HA）及富里酸（FA）对还原的影响，并利用TEM、EDS、SAED和XPS对还原后的样品进行了表征。结果表明：在pH=7.0、c_NaHCO3=5 mmol/L和T=303 K条件下，Bacillus sp.dwc-2对U(Ⅵ)的还原率随时间的增加而增加，24 h内最大还原率为12.2%，此后则随时间的增加逐渐降低；HA和FA对U(Ⅵ)的微生物还原行为有一定影响，其中HA和FA浓度为25 mg/L时，U(Ⅵ)的还原在24 h最明显，其还原率分别为14.2%和16.2%，但随着HA和FA浓度的继续增加，因在U(Ⅵ)离子与HA、FA形成的配合物表面形成致密的腐殖层，抑制了电子的转移，阻止了U(Ⅵ)的还原。此外，研究表明HCO₃^-也会抑制U(Ⅵ)的还原。TEM-SAED和XPS分析证实了还原过程中U(Ⅳ)的存在。上述结果可为真实环境中微生物还原U(Ⅵ)提供基础数据和参考。     

Irradiation-induced large bubble formation and grain growth in super nano-grained ceramic

In this work, 0.5TRPO•0.5Gd₂Zr₂O₇ ceramic with an average grain size of only ∼15 nm was prepared by a high pressure (5 GPa/520 °C) sintering method. Phase evolutions and microstructure changes of the as-fabricated super nano and micron-grained ceramics under a high-dose displacement damage induced by 300 keV Kr²⁺ ions were investigated. The results show that the super nano-grained ceramic has low degree of amorphization, obvious grain growth (2–3 times in grain size) and big Kr bubbles (10–68 nm) formation after irradiation. The micron-grained ceramic was severely amorphized after irradiation and many microcracks were formed parallel to its surface. The formation mechanism of Kr bubbles in the super nano-grained ceramic is on account of grain boundary diffusion and migration induced by the accumulation of the injecting Kr ions and irradiation defects. Nevertheless, microcracks formed in the micron-grained sample are caused by the accumulation of Kr atoms.