Meticulously tailoring phase boundary in KNN-based ceramics to enhance piezoelectricity and temperature stability

Although KNN-based ceramics with high electrical properties are obtained through a variety of strategies, the temperature sensitivity is still one of the key technical bottlenecks hindering practical applications. Here, we use a new strategy, meticulously tailoring phase boundary, to refine the ferroelectric boundary of KNN-based ceramics, leading to high piezoelectricity companied with improving temperature stability. The highest d₃₃ value in this system reaches 501 pC/N with a T_C ∼ 240°C, whereas a large strain of ∼0.134% can be kept with 10% lower deterioration until 100°C. The origin of high piezoelectricity is mainly attributed to the well-preserved multiphase coexistence and the appearance of nanodomains, which greatly facilitate the polarization rotation. Instead of the changed intrinsic thermal insensitivity, the precision phase boundary engineering plays an important role in strengthening the temperature stability of electric-induced strain. This work provides a simple and effective method to obtain both high electrical properties and excellent thermal stability in KNN-based ceramics, which is expected to promote the practical applications in the future.     

Sea urchin-like LiAlO2@NiCoO2 hybrid composites with core-shell structure as high-performance Li storage materials

Sea urchin-like LiAlO₂@NiCoO₂ hybrid composites with core-shell structure assembled with nanoneedles have been successfully fabricated through a facile hydrothermal route followed by a calcination procedure in N₂ for the first time. The sea urchin-like architecture with large accessible surface can offer numerous active sites for redox reaction. The synergy of two advantages has dramatically improved the electrochemical behavior in terms of specific capacity, cycle performance and rate capability, especially at high current densities. The LiAlO₂(5.0 wt%)@NiCoO₂ displays charge capacities are 1309.0 and 933.6 mAh g^?1 at 0.5 and 1A g^?1, respectively, after 400 cycles. However, the charge capacities of bare NiCoO₂ are only 562.9 and 476.7 mAh g^?1 at corresponding rates. Especially, LiAlO₂(5.0 wt%)@NiCoO₂ preserves 358.1 mAh g^?1 after 500 cycles at 2A g^?1 with a capacity retention of 74%. The superior electrochemical property is related to the sea urchin-like nature and the ingenious composition design. In addition, the DFT calculation result shows that the formed stable, well-coordinated, and metallic interface between LiAlO₂ and NiCoO₂ are very helpful for reducing the interfacial impedance and beneficial for the improved rate capability of the materials. Therefore, such LiAlO₂@NiCoO₂ composites with unique morphology demonstrate a huge potential as electrode materials for Li-ion batteries.     

南方地区造纸车间钢屋面保温厚度的计算与分析

本文从内表面防结露、夏季隔热2个角度出发，对夏热冬冷及夏热冬暖地区代表城市采用的钢结构屋面的保温（隔热）层厚度进行计算分析。研究表明，在夏季室内温、湿度达到某一状态时，隔热厚度要大于冬季防结露的保温厚度。因此，夏热冬冷地区的造纸车间钢屋面保温层厚度应按夏季隔热计算确定，并进行冬季防结露验算；夏热冬暖地区按照冬季防结露计算即可。     

Research on the effects of surface modification of ceramic powder on cure performance during digital light processing (DLP)

Digital light processing (DLP) is one of the most important additive manufacture technologies to fabricate ceramic parts with complex geometries. Compared with pure photosensitive resin, the cure performance of ceramic suspensions is obviously different due to the optical property change after the addition of ceramic powders. In this paper, a unique oxidation process was used to modify the optical properties of nitride powders including AlN and Si₃N₄. The properties of oxidized ceramics were investigated and the cure performance of ceramic suspensions was then characterized. The effect of oxidation time on cure performance was evaluated. The results showed that for AlN, oxidation process leads to the smaller cure depth and smaller excess cure width as compared with non-oxidized AlN and for Si₃N₄, oxidation process leads to the larger cure depth and larger excess cure width as compared with non-oxidized Si₃N₄, indicating that both refractive index and light absorbance of ceramic powders have obvious effects on cure behaviors. Additionally, the cure behavior of oxidized ceramic suspension in this study shows that the relationship of cure depth vs. incident energy agrees well with Beer- Lambert model, but the excess cure width vs. incident energy is not consistent with quasi Beer-Lambert model due to the nature of digital micromirror device (DMD).     

Growth,mechanical properties,and tribological performance of TiAlN/NbN and NbN/TiAlN bilayer coatings

Three different coatings, namely TiAlN, TiAlN (external)/NbN (internal) and NbN (external)/TiAlN (internal), were deposited on cemented carbides by arc ion plating. The comparative investigation conducted in this study elucidates the effect of the NbN layer and coating systems on the growth, mechanical properties, and tribological performance of the coatings. The results showed that the surface of the TiAlN and TiAlN/NbN coatings was smoother when TiAlN served as the external layer. The NbN/TiAlN coating, wherein NbN formed the external layer, had a much rougher but more symmetrical surface. With the introduction of the NbN layer, the increased micro stress induced a lower adhesion strength in the TiAlN/NbN and NbN/TiAlN coatings. The TiAlN/NbN and NbN/TiAlN coatings exhibited higher hardness and hardness/effective elastic modulus (H/E*). During the friction test, when the temperature was elevated to 700 °C, the tribological performance of the monolayer TiAlN coating was the lowest because of the TiO₂-induced breakage of the dense tribo-oxide film. The NbN layer participated in the formation of a NbO_x film at elevated temperatures, which was responsible for the high tribological performance of the two bilayer coatings. When the NbN layer was on the outermost layer and in direct contact with the elevated temperature atmosphere, the NbN/TiAlN coating generated a tribo-oxide film with high integrity, and its coefficient of friction decreased by 27% of that at room temperature. Therefore, the NbN/TiAlN coating exhibited the highest wear resistance at 700 °C.     

Fabrication and thermoelectric properties of SrTiO3–TiO2 composite ceramics

The paper presents the results of preparing biphase SrTiO₃–TiO₂ ceramics as a promising system for n-type thermoelectrics using the features of a two-dimensional electron gas. Ceramics was obtained by reactive spark plasma sintering of SrCO₃ and TiO₂. The dynamics of phase transformations are shown; it is clarified that phase transformations are not the driving force of sintering. The mutual stabilization of the SrTiO₃ and TiO₂ phases is shown. Unique data on the assessment of the temperature gradient in the system have been obtained. A comparison of the thermoelectric characteristics of biphasic ceramics and its constituent phases allows concluding that the role of the two-dimensional electron gas is reduced to modulating the properties of bulk phases. Clear signs of size quantization were detected by the X-ray luminescence method, which is expressed in the blueshift of the luminescence spectrum by 22.3 ± 0.8 meV.     

Determination of olaquindox,carbadox and cyadox in animal feeds by ultra-performance liquid chromatography tandem mass spectrometry

Olaquindox, carbadox, and cyadox are chemically synthesised antibacterial and growth-promoting agents for animals. At high doses they may exert mutagenicity and hepatic and adrenal toxicities in animals. Regrettably, these substances are frequently abused or misused when added into animal feeds. Thus, developing a sensitive and reliable method for simultaneous determination of olaquindox, carbadox, and cyadox in different kinds of animal feeds is crucially important for food safety monitoring. In this paper we optimised instrumental conditions, extraction solvents, solid phase extraction cartridges, and pH of the loading solvents on the Oasis HLB cartridge. Under the optimal conditions, mean recoveries ranged from 74.1 to 111%, and intra-day and inter-day variations were lower than 14.6% and 10.8%, respectively. The limits of quantification for olaquindox, carbadox, and cyadox were 0.05 mg kg^?1, 0.10 mg kg^?1, and 0.025 mg kg^?1, respectively. The proposed method uses ultra-performance liquid chromatography tandem mass spectrometry and is sensitive and reliable for the simultaneous determination of olaquindox, carbadox, and cyadox in three kinds of animal feeds (specifically, mixed feed, concentrated feed, and additive premixed feed). This method has good precision, high sensitivity, and good reproducibility, and thus it can be used for convenient and accurate determination of olaquindox, carbadox, and cyadox in different kinds of animal feeds.     

分析铁路改良粉细砂填料应用性能试验

在设计铁路路基的填料时,最常出现的是在进行铁路建设的地方就地取材。在以粉细砂为主的地区通常会选择用粉细砂作为铁路的填料,在所有的填料中,粉细砂填料属于C组类型填料,但是因为两个方面的原因需要对其进行一定的改良,一方面是因为粉细砂的粒径比较单一、级配不好,K30不能够满足规范标准的要求;另一方面则是因为大型机械不能够进行施工。本文通过掺入不同体积A、B组砾砂填料到粉细砂填料中进行试验,结果显示这种操作可以在不同程度上提高K30的值,从而在达到相关设计要求的同时解决施工方面的难题。     

Chia Seed Oil Prevents High Fat Diet Induced Hyperlipidemia and Oxidative Stress in Mice

Hyperlipidemia is a common cardiovascular disease. At present, the influence of high fat diet (HFD) on this is being explored. Recently, vegetable oils rich in omega‐3 have been reported that can treat hyperlipidemia caused by HFD. However, the effects of chia seed oil (CSO) on HFD‐induced hyperlipidemia and oxidative stress are poorly studied. Hence, in this study, the effects of CSO on hyperlipidemia and oxidative stress induced by HFD in mice are analyzed by various commercial kits, section staining, and protein expression. The results show that CSO decreases body weight and organ index. Meanwhile, CSO reduces serum lipid levels of total cholesterol, triglyceride, and low‐density lipoprotein cholesterol. It can also elevate superoxide dismutase and glutathione peroxidase activities and reduce malondialdehyde content in serum and liver. The results of histopathological analysis prove that CSO improves hepatic steatosis and reduces lipid deposition. Further, the results of western blot demonstrate that CSO upregulates the expression of peroxisome proliferator‐activated receptor alpha and carnitine palmitoyltransferase 1a in the liver. As a result, CSO may be a potential lipid‐lowering oil to prevent and treat HFD‐induced hyperlipidemia and oxidative stress. Practical Applications CSO, as a byproduct of chia seed processing, is a rich source of α‐linolenic acid. This study investigates the effects of CSO on HFD‐induced hyperlipidemia and oxidative stress in mice. It is concluded that dietary CSO can improve the hyperlipidemia in HFD‐induced mice via analysis of lipid parameters, histopathology study of the liver, and lipid metabolism related genes. In addition, supplementation of CSO also can improve the oxidative stress in mice. Therefore, CSO can be used for the prevention of hyperlipidemia and oxidative stress. This research provides a theoretical basis for the comprehensive development and utilization of functional chia seed oil.     

Tribological behavior studies of chemically bonded phosphate ceramic coatings reinforced with modified multi-walled carbon nanotubes (MWCNTs)

To improve the wear resistance of the chemically bonded phosphate ceramic coatings, MWCNTs are selected as the reinforcement after the modification. The high temperature wear experiment is carried out to investigate the wear behavior of the coatings with different temperatures. The results suggest that, when the temperature is below 500℃, MWCNTs can decrease friction coefficient, and the lowest friction coefficient is about 0.28, but MWCNTs lose the lubricant function at 500℃ and the friction coefficient keeps at the level of ~ 0.68. In addition, the wear resistance of coatings is improved with the introduction of MWCNTs at 100℃ and 300℃ (the wear rate is below 15X10^-3mm³/Nm), but keeps similar level at 500℃ (the wear rate is ~ 22 × 10⁻³mm³/Nm). Besides, the wear mechanism of the coatings reinforced by MWCNTs is also investigated based on the wear behavior and microstructural characterizations. MWCNTs improve the fracture toughness by preventing the crack generation and forming the bridge when crack occurs, which leads to smooth wear tracks and good wear resistance of coatings. The coatings with MWCNTs achieve poor wear resistance at 500℃ because MWCNTs lose their strength and resistance to fatigue by oxidizing.