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Purpose: This study aims to investigate the effect of V doping on the microstructure, chemical stability, mechanical and vacuum tribological behavior of sputtered MoS2 coatings. Design/methodology/approach: The MoS2-V coatings are fabricated via tuning V target current by magnetron sputtering technique. The structural characteristic and elemental content of the coatings are measured by field emission scanning electron microscopy, X-ray diffractometer, electron probe X-ray micro-analyzer, Raman, X-ray photoelectron spectroscopy, high resolution transmission electron microscope and energy dispersive spectrometer. The hardness of the deposited coatings are tested by a nanoindentation technique. The vacuum tribological properties of MoS2-V coatings are studied by a ball-on-disc tribometer. Findings: Introducing V into the MoS2 coatings results in a more compact microstructure. The hardness of the coatings increases with the doping of V. The MoS2-V coating deposited at a current of 0.2 A obtains the lowest friction coefficient (0.043) under vacuum. As the amount of V doping increases, the wear rate of the coating decreases first and then increases, among which the coating deposited at a current of 0.5 A has the lowest wear rate of 2.2 × 10–6 mm3/N·m. Originality/value: This work elucidates the role of V doping on the lubrication mechanism of MoS2 coatings in a vacuum environment, and the MoS2-V coating is expected to be applied as a solid lubricant in space environment. [ABSTRACT FROM AUTHOR]

Adequate water intake and optimal hydration status during pregnancy are crucial for maternal and infant health. However, research on water intake by pregnant women in China is very limited. This study mainly aimed to observe the daily total water intake (TWI) of pregnant women and its different sources and to investigate the relationship between their water intake and hydration biomarkers. From October to November 2020, a convenience sample of pregnant women in the second trimester (n = 21) was recruited. Under conditions close to daily life, they undertook a 3-day metabolic trial. Each participant was provided with sufficient bottled water, and the weight of what they drank each time was measured. The intake of other beverages and foods was measured using a combination of weighing and duplicate portion method. Fasting venous blood and 24 h urine samples were collected and analyzed for the hydration biomarkers, including the serum/urine osmolality, urine pH, urine specific gravity, and the concentrations of major electrolytes in urine and serum. The results showed that the mean daily TWI was 3151 mL, of which water from beverages and foods accounted for 60.1% and 39.9%, respectively. The mean total fluid intake (TFI) was 1970 mL, with plain water being the primary contributor (68.7%, r = 0.896). Among the participants, 66.7% (n = 14, Group 1) met the TWI recommendation set by the Chinese Nutrition Society. Further analysis revealed that the TFI, water from beverages and foods, plain water, and milk and milk derivatives (MMDs) were significantly higher in Group 1 than those who did not reach the adequate intake value (Group 2) (p < 0.05). The results of hydration biomarkers showed that the mean 24 h urine volume in Group 1 was significantly higher than that in Group 2 (p < 0.05), while the 24 h urine osmolality, sodium, magnesium, phosphorus, chloride, and creatinine concentrations in Group 1 were significantly lower than those in Group 2 (p < 0.05). However, no significant differences were observed in serum biomarkers. Partial correlation analysis showed that TWI was moderately positively correlated with 24 h urine volume (r = 0.675) and negatively correlated with urine osmolality, sodium, potassium, magnesium, calcium, phosphorus, and chloride concentrations (r = from−0.505 to −0.769), but it was not significantly correlated with serum biomarkers. Therefore, under free-living conditions, increasing the daily intake of plain water and MMDs is beneficial for pregnant women to maintain optimal hydration. The hydration biomarkers in urine are more accurate indicators of water intake and exhibit greater sensitivity compared to serum biomarkers. These findings provide a scientific basis for establishing appropriate water intake and hydration status for pregnant women in China. [ABSTRACT FROM AUTHOR]

(1‐x)(Li0.02Na0.5K0.48)(Nb0.95Sb0.05)O3‐x(Bi0.5Na0.5)(Zr0.97W0.01Fe0.02)O3 (LNKNbS‐xBiNZWF, x = 0.035, 0.04, 0.045, 0.05, and 0.055) lead‐free piezoceramics were fabricated by traditional solid‐state sintering method via two‐step sintering technique, where the effects of BiNZWF doping amount and ceramic processing were studied systematically. The formation of orthorhombic‐tetragonal (O‐T) phase boundary in the LNKNbS‐xBiNZWF system is confirmed by X‐ray diffraction Rietveld refinement and Raman spectroscopy, where the BiNZWF doping amount affects the O‐T phase proportion. The LNKNbS‐xBiNZWF ceramics approach to normal ferroelectrics but have apparent relaxation characteristic. Oxygen vacancies dominate the high‐temperature conduction in the LNKNbS‐0.04BiNZWF ceramics, which are generated by the volatilization of Bi and alkali metals during sintering. The LNKNbS‐0.04BiNZWF ceramics exhibit excellent electrical properties, correlating with using the two‐step sintering method, appropriate proportion of O phase and T phase, high densification and improved microstructure uniformity. [ABSTRACT FROM AUTHOR]

Boron nitride nanoplatelet (BNNPs) with superior mechanical properties can be a promising candidate as reinforcement to improve the toughness of glass–ceramics. Herein, glass–ceramics composites reinforced with well‐dispersed BNNPs are fabricated by spark plasma sintering. The addition of BNNP enhances the mechanical properties of glass–ceramics and inhibits the nucleation and growth of the diopside. The number of diopsides and the grain size gradually decrease with the increase of BNNP content. The mere addition of 1.0 wt% BNNPs can simultaneously increase the hardness and fracture toughness by 7.94% and 22.54%, respectively. Crack deflection, BNNP pull‐out, crack blocking, and crack bridging are the main toughening mechanisms, and the toughening model is established to optimize the design of BNNP‐reinforced composites. [ABSTRACT FROM AUTHOR]

The intercalation capacity at low potential of carbon‐based anode plays a significant role for developing potassium ion batteries (PIBs) with high energy density. However, the inferior rate and cyclic performance caused by repeated insertion/extraction of large K+ tremendously restricts the practical application of PIBs. Herein, a quasi‐graphite structure with abundant edge‐nitrogen doping, micropores structure, and enhanced graphite nanodomains via in situ polymerization of oligoaniline in‐between graphene oxide blocks and subsequent carbonization is proposed. The macro‐ordered multilayered structure with micro‐ordered graphite nanodomains can provide efficient K+ insertion/extraction channels, thus greatly increasing the intercalation capacity at low potentials. Moreover, the high edge‐nitrogen doping (97%) is of great importance for improving K+ transfer kinetics, particularly at high current densities. As a result, the anode exhibits a high discharge capacity below 0.5 V (303 mAh g−1 at 0.05 A g−1), outstanding rate performance (113 mAh g−1 at 5 A g−1), and long‐term cycle stability (176 mAh g−1 at 1 A g−1 after 2000 cycles). The K+ intercalation mechanism and enhanced kinetics are systematically probed by in situ Raman spectroscopy, ex situ X‐ray diffraction (XRD) spectra, and theoretical calculations. This results demonstrate that the construction of quasi‐graphite with heteroatom doping is feasible for large ion storage. [ABSTRACT FROM AUTHOR]

The efficiency of antimony selenide (Sb2Se3) solar cells is still limited by significant interface and deep‐level defects, in addition to carrier recombination at the back contact surface. This paper investigates the use of lithium (Li) ions as dopant for Sb2Se3 films, using lithium hydroxide (LiOH) as a dopant medium. Surprisingly, the LiOH solution not only reacts at the back surface of the Sb2Se3 film but also penetrate inside the film along the (Sb4Se6)n molecular chain. First, the Li ions modify the grain boundary's carrier type and create an electric field between p‐type grain interiors and n‐type grain boundary. Second, a gradient band structure is formed along the vertical direction with the diffusion of Li ions. Third, carrier collection and transport are improved at the surface between Sb2Se3 and the Au layer due to the reaction between the film and alkaline solution. Additionally, the diffusion of Li ions increases the crystallinity, orientation, surface evenness, and optical electricity. Ultimately, the efficiency of Sb2Se3 solar cells is improved to 7.57% due to the enhanced carrier extraction, transport, and collection, as well as the reduction of carrier recombination and deep defect density. This efficiency is also a record for CdS/Sb2Se3 solar cells fabricated by rapid thermal evaporation. [ABSTRACT FROM AUTHOR]

Briefly, 0.005-mol Sm3+-doped (Ba0.85Ca0.15)(Ti0.9Hf0.1)O3 ([(Ba0.85Ca0.15)0.995Sm0.005](Ti0.9Hf0.1)O3, BCTH:0.005Sm3+) lead-free ceramics were prepared via hydrothermal method and powder injection molding using paraffin and oleic acid as binders, and the effects of preparation method and sintering conditions on microstructure, dielectric behavior and optical properties were investigated. XRD Rietveld refinement reveals the coexistence of orthogonal, rhombohedral and tetragonal phases, in which the crystal structure and phase fraction are influenced greatly by sintering temperature and holding time. The ceramics present enhanced relaxor behavior and frequency dispersion phenomenon as compared with those prepared by the solid-state sintering method, and the diffusive index γ value is within 1.421–1.673. The transition mechanism and luminescence performance of BCTH:0.005 Sm3+ were analyzed by Blasse formula, photoluminescence spectrum and fluorescence lifetimes, where emission peaks show slight blueshift, fluorescence decay lifetime becomes shorter, electric multipole interaction dominates the energy transfer mechanism, and the down-conversion luminescence is one-photon absorption process. The CIE chromaticity color coordinate (0.4746, 0.5048), correlated color temperature 3134 K and color purity 93.58% are achieved, which reveals that the BCTH:0.005 Sm3+ ceramics express high quality yellow emission rather than orange-red light of the hydrothermal method synthesized nano-powder, and have potential application in optical field. [ABSTRACT FROM AUTHOR]