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This paper presents a dual-core two-parameter optical fiber sensor based on the surface plasmonic resonance (SPR) effect. It is analyzed by the finite element method. The proposed sensor is a dual-channel structure designed with photonic crystal fiber (PCF) as the base material: one channel is coated with a gold film to measure the refractive index (RI) of the solution to be measured, and the other channel is coated with a gold film and polydimethylsiloxane to measure the temperature of the solution to be measured. The exposed microslot structure on both sides reduces the complexity of sensing measurements. The results show that the maximum RI sensitivity of the sensor is 19,900 nm/RIU, and the maximum sensitivity to temperature is 8.7 nm/℃. This work is conducive to realizing a PCF sensor with high sensitivity, large measurement range, real-time monitoring, and easy preparation. As a result, the sensor is expected to be widely used in fields such as biology and chemicals. [ABSTRACT FROM AUTHOR]

The low sintering temperature (LST) is a great significance for the fabrication of sensors and electronic components. To exploit a system of LST negative temperature coefficient (NTC) thermistors, Mn/La co-doped WO3 ceramics (MnxLa0.03WO3+δ, x ≤ 0.1, denoted as xMLW) were prepared in this work by a traditional solid-state reaction technology. The phase component, microstructure, and electrical property of the prepared xMLW ceramics were investigated. The xMLW ceramics have the main phase with lattice structure as that of monoclinic WO3 with a space group of P21/n, and show typical NTC characteristics. By varying the concentration of Mn cations, the xMLW ceramics have adjustable room temperature resistivity (ρ25) ranging from 770 Ω·cm to 7.017 kΩ·cm and high thermal-sensitivity constants (B value) ranging from 2695 to 4219 K. The electrical conduction and NTC feature of the ceramics are discussed by analyzing impedance spectrum and lattice defect. [ABSTRACT FROM AUTHOR]

Surface plasmon resonance (SPR) sensing methods enable highly sensitive, fast response, and label-free analysis of biomolecular interactions. For SPR sensors, sensitivity and full width at half maximum (FWHM) are two incompatible performance parameters. We propose a refractive index (RI) sensor using a dual-core photonic crystal fiber (PCF) and SPR effects to achieve high sensitivity and a narrow FWHM simultaneously. The air holes of the sensor appear in a hexagonal arrangement, and polishing technology introduces two polishing planes into the cladding. A gold film is deposited on one side of the polished plane to form a highly sensitive RI sensing channel. Five gold nanowires are deposited on the other side of the polished plane to form a RI sensing channel with a narrow FWHM. We analyzed and optimized its structural parameters using the finite element method and determined the optimal structural parameters. The numerical results demonstrate that the maximum sensitivity of the sensor is 21,000 nm/RIU with the narrowest FWHM of 31 nm. Therefore, measuring the refractive index simultaneously with two sensing channels increases the detection accuracy of the measurement. In addition, the findings further indicate that variations in structural parameters do not significantly impact the sensing performance of the sensor, which makes the production of the sensor relatively simple. In conclusion, our work provides a new research method for realizing high sensitivity and a narrow FWHM simultaneously. [ABSTRACT FROM AUTHOR]

The negative temperature coefficient (NTC) thermosensitive ceramics with low sintering temperature are of great significance in the research and application of low-temperature co-firing sensitive components. In this work, bismuth-modified samarium cuprate (BixSm2-xCuO4, denoted as xBSCO, x ≤ 0.1) thermistors were prepared by a solid-state reaction method. All ceramics were sintered below 950 °C and show typical NTC effect. The phase component, microstructure, electrical properties of prepared ceramics were investigated. The substitution of Bi-ions reduces the room temperature resistivity (ρ25) of the ceramics. For various contents of Bi-ions, ρ25 of xBSCO ranges from 76 Ω cm to 1297 Ω cm, and all the ceramics have high temperature sensitivity with NTC material constants (B values) between 2237 and 5150 K. The temperature coefficient of resistance at 25 °C (TCR25) of xBSCO is in the range − 5.48% K−1 to − 2.30% K−1. The effect of Bi doping on the structure and property of Sm2CuO4 ceramics is discussed basing on the perspective of band structure. [ABSTRACT FROM AUTHOR]

Transition metal oxides are promising candidates for the next generation of spintronic devices due to their fascinating properties that can be effectively engineered by strain, defects, and microstructure. An excellent example can be found in ferroelastic LaCoO3 with paramagnetism in bulk. In contrast, unexpected ferromagnetism is observed in tensile-strained LaCoO3 films, however, its origin remains controversial. Here we simultaneously reveal the formation of ordered oxygen vacancies and previously unreported long-range suppression of CoO6 octahedral rotations throughout LaCoO3 films. Supported by density functional theory calculations, we find that the strong modification of Co 3d-O 2p hybridization associated with the increase of both Co-O-Co bond angle and Co-O bond length weakens the crystal-field splitting and facilitates an ordered high-spin state of Co ions, inducing an emergent ferromagnetic-insulating state. Our work provides unique insights into underlying mechanisms driving the ferromagnetic-insulating state in tensile-strained ferroelastic LaCoO3 films while suggesting potential applications toward low-power spintronic devices. Transition metal oxides are a promising class of materials to engineer multiferroic properties for next-generation spintronic devices. Here, the authors demonstrate an emergent and robust ferromagnetic-insulating state in ferroelastic LaCoO3 epitaxial films by strain-defect-microstructure manipulated electronic and magnetic states. [ABSTRACT FROM AUTHOR]

A D-shaped photonic crystal fiber (PCF) surface plasmon resonance (SPR) sensor is proposed to measure the refractive index in visible and near-infrared regions. Compared with traditional PCF, the use of D-shaped PCF can avoid filling materials and coatings in the hole. The plasma material of sensors is silver, and graphene is coated on the surface of the silver film. Graphene layer can not only prevent the oxidation of the silver but also improve the performance of the sensor. Then the influence of structural parameters on the sensor performance is studied by the finite element method (FEM). Results show that the performance of the sensor is not sensitive to the structural parameters, which makes the sensor has a good manufacturing tolerance. Moreover, when the refractive index (RI) of the analyte is 1.33 ~ 1.41, the maximum wavelength sensitivity is 13,750 nm/RIU, and the corresponding RI resolution is 7.27 × 10−6 RIU−1. In addition, the maximum figure of merit is 201 RIU−1. The proposed sensor is advanced with high sensitivity, simple structure and big fabrication tolerance, which could become a competitive candidate for water pollution monitoring, medical diagnosis, biochemical analysis, and detection fields. [ABSTRACT FROM AUTHOR]

The wide use of polyacrylamide (PAM) in enhanced oil recovery generates a large amount of polymer-bearing wastewater featuring high viscosity and difficult viscosity reduction, making the treatment of wastewater increasingly difficult. In this paper, the experimental study on reducing the viscosity of wastewater containing polyacrylamide by using the plasma generated by dielectric barrier discharge (DBD) and the synergistic effect of catalyst γ-Al2O3 is carried out. The law of plasma reducing the viscosity of wastewater containing polyacrylamide is studied under the different conditions of amounts of γ-Al2O3 catalyst, discharge voltages, and initial concentrations of polyacrylamide-containing wastewater. The mechanism of viscosity reduction of polyacrylamide is studied through environmental scanning electron microscope (ESEM), Fourier transform infrared (FTIR) spectrometer, and X-ray photoelectron spectroscopy (XPS). The results show that the catalytic viscosity reduction is the best when the discharge voltage is 18 kV and the discharge time is 15 min. With the increase in the input of the γ-Al2O3 catalyst, the viscosity of the PAM solution decreases gradually. When the amount of γ-Al2O3 is 375 mg, the shear rate changes from 0.5 1/sec to 28 1/sec, and the viscosity of the solution containing polyacrylamide changes from 434.5 mPa·s to 40.2 mPa·s. The viscosity reduction rate of the PAM solution is 90.7%. After the catalytic viscosity reduction, the functional groups of polyacrylamide do not change much. The elemental composition of the catalyst has not changed, which is still Al, C, and O. [ABSTRACT FROM AUTHOR]

Projecting how the East Asian summer monsoon (EASM) rainfall will change with global warming is essential for human sustainability. Reconstructing Holocene climate can provide critical insight into its forcing and future variability. However, quantitative reconstructions of Holocene summer precipitation are lacking for tropical and subtropical China, which is the core region of the EASM influence. Here we present high-resolution annual and summer rainfall reconstructions covering the whole Holocene based on the pollen record at Xinjie site from the lower Yangtze region. Summer rainfall was less seasonal and ~ 30% higher than modern values at ~ 10-6 cal kyr BP and gradually declined thereafter, which broadly followed the Northern Hemisphere summer insolation. Over the last two millennia, however, the summer rainfall has deviated from the downward trend of summer insolation. We argue that greenhouse gas forcing might have offset summer insolation forcing and contributed to the late Holocene rainfall anomaly, which is supported by the TraCE-21 ka transient simulation. Besides, tropical sea-surface temperatures could modulate summer rainfall by affecting evaporation of seawater. The rainfall pattern concurs with stalagmite and other proxy records from southern China but differs from mid-Holocene rainfall maximum recorded in arid/semiarid northern China. Summer rainfall in northern China was strongly suppressed by high-northern-latitude ice volume forcing during the early Holocene in spite of high summer insolation. In addition, the El Niño/Southern Oscillation might be responsible for droughts of northern China and floods of southern China during the late Holocene. Furthermore, quantitative rainfall reconstructions indicate that the Paleoclimate Modeling Intercomparison Project (PMIP) simulations underestimate the magnitude of Holocene precipitation changes. Our results highlight the spatial and temporal variability of the Holocene EASM precipitation and potential forcing mechanisms, which are very helpful for calibration of paleoclimate models and prediction of future precipitation changes in East Asia in the scenario of global warming. [ABSTRACT FROM AUTHOR]

Purpose: The aim of the study was to investigate habitual vitamin E intake and plasma α-tocopherol concentration and their relationship with plasma fatty acid profile in a healthy adult population. Methods: Vitamin E and fatty acid intake data were determined from the National Adult Nutrition Survey. Plasma α- and γ-tocopherol concentrations were quantified by high-performance liquid chromatography and the percentage of fatty acids in plasma by gas chromatography coupled with mass spectrometry. Participants ( n = 601) were divided into vitamin E intake quartiles and plasma α-tocopherol quartiles, and differences in fatty acid intake and plasma fatty acid profile were analyzed by a general linear model. Results: Dietary intake data showed that as vitamin E intake increased, intakes of total polyunsaturated fatty acid (PUFA) and α-linolenic acid increased significantly ( p < 0.001), but eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) did not. After adjusting for fatty acid intake, vitamin E intake was positively related to plasma n-3 PUFA (EPA and DHA) levels and plasma n-3/n-6 PUFA ratio. Plasma α-tocopherol concentration was positively related to the percentage of plasma total PUFA, n-3 PUFA and EPA and inversely related to the percentage of plasma n-6 PUFA. Conclusions: The study illustrates that there are statistical relationships between plasma fatty acid profile and both vitamin E intake and plasma α-tocopherol concentration. Vitamin E may play a role in the maintenance of plasma n-3 PUFA profile in humans with consequent desirable health effects. [ABSTRACT FROM AUTHOR]

Triple-frequency global navigation satellite systems allow the introduction of additional linear observation combinations. We define two geometry-free phase combinations and one geometry-free pseudorange minus phase linear combination to detect and correct cycle slip in real time. At first, the optimal BDS (BeiDou System) triple-frequency geometry-free phase combinations are selected for cycle slip detection. Then, a detailed analysis of the cycle slip detection is performed by examining whether some special cycle slip groups cannot be discovered by the selected combinations. Since there still remain some cycle slip groups undetectable by the two geometry-free phase combinations, we add a pseudorange minus phase linear combination which is linearly independent with these two phase combinations, to be sure that all the cycle slips can be detected. After that, an effective decorrelation search based on LAMBDA and least squares minimum principle is applied to calculate and determine the cycle slips. The method has been tested on triple-frequency undifferenced BDS data coming from a benign observation environment. Results show that the proposed method is able to detect and repair all the small cycle slips in the three carriers. [ABSTRACT FROM AUTHOR]

The temporal-spatial distribution features of prehistoric cultures since the Holocene in Zhejiang region were comparatively analyzed based on GIS spatial analysis. Results show that the prehistoric cultures expanded gradually in this region before 4000 cal. a BP. The notable expansions occurred twice, one in the Majiabang-Hemudu cultural period, the other in the Liangzhu cultural period. Meanwhile, the prehistoric cultures were disseminated from west to east coast along river valleys. After 4000 cal. a BP, as represented by the Maqiao Culture, the distributed area of each prehistoric culture contracted. This is obviously due to the termination of spreading trends to east coast, which was simultaneously accompanied by two different modes of production and economic transitions in the north and south Zhejiang region respectively. The distribution of prehistoric cultures was closely related with Holocene sea-level fluctuations, especially on the banks of Hangzhou Bay, where the distribution changes of prehistoric cultural sites were greatly affected by sea-level changes, with the closest relationships between them. After 7000 cal. a BP, the process of lowered sea-level and regression-epeirogenesis provided wider terrestrial living spaces for prehistoric inhabitants. Based on the comparative analyses of the changes of prehistoric cultures and the environmental evolution information recorded in the Qianmutian subalpine peat of Mt. Tianmu and muddy area on the inner shelf of the East China Sea, it is indicated that the changes of prehistoric cultures were synchronized with environmental changes in Zhejiang region. Before 4000 cal. a BP, the eastward expansion of prehistoric cultures in Zhejiang occurred under the background of the Holocene Optimum, and was the expansion and extension under the joint influences of agricultural civilization and maritime civilization. However, after 4000 cal. a BP, the geographical contraction of prehistoric cultures in Zhejiang occurred under the back ground of dry-cold climate trend and deterioration of coastal marine environment. It is evidenced from the above fact that the development, expansion and contraction of prehistoric cultures are positively correlated to environmental change. The change of the climatic environment is just the underlying reason for these changes and transitions of production modes and economic forms. Therefore, the climatic environment is the dominant factor of prehistoric culture vicissitudes in Zhejiang region, which has exerted great influence on distribution, dissemination, expansion and transmutation of the culture. [ABSTRACT FROM AUTHOR]

In order to understand physicochemical properties of water-soluble proteins obtained from crucian carp, turbidity, total sulfhydryl content, hydrophobicity and SDS-PAGE of crucian carp water-soluble proteins during heat treatment were investigated. Turbidity remained unchanged up to 44°C and considerably increased from 46°C to 54°C, one peak of increase rate was found at 50°C; total SH content decreased rapidly when heated from 50°C to 55°C; hydrophobicity increased sharply when heated up to 45°C, indicating the conformation of water-soluble proteins from crucian carp began to unfold and expose the buried nonpolar amino acids at temperatures above 45°C; analysis of SDS-PAGE indicating the formation of disulfide linkage of creatine kinase and glyceraldehy-3-phosphate dehydrogenase when the temperature reached 65°C and 80°C, respectively. [ABSTRACT FROM AUTHOR]

This study presents an analysis of the spatial-temporal distribution of 230 archaeological sites in Guizhou Province, Southwest China for three selected time periods from the Paleolithic Age to the Shang-Zhou Dynasties. The relationship between archaeological sites distribution and environmental changes is also discussed based on paleo-environmental proxies of δO and δC recorded in stalagmites from Southwest China. The results show that: in the Paleolithic Age (260−10 ka BP), archaeological sites were concentrated in the central, northwestern and southwestern parts of Guizhou, where the high-altitudinal karst landforms with many natural caves suitable for human habitation are developed. In the Neolithic Age (10−3.6 ka BP), most of human settlements were concentrated in the central, northwestern and southwestern parts, while, a fewer sites were found on river terraces in the southern and eastern parts, and the intermontane basins in the central and western Guizhou. During the Shang-Zhou Dynasties (3.6−2.2 ka BP), the sites were mainly distributed in the intermontane basins and on river terraces, which were suitable for primitive aerial farming. The analysis of paleo-environmental proxies of δO and δC since 260 ka BP suggested that climate fluctuations had little impact on human settlements in this study area. The distinct physical environment, especially the spatial patterns of karst landforms and arable land played an important role in the archaeological sites distribution of Guizhou. [ABSTRACT FROM AUTHOR]

Nb-doped SrSnO3 (SSNO) thin films were epitaxially grown on LaAlO3(001) single-crystal substrates using pulsed laser deposition under various oxygen pressures and substrate temperatures. The crystalline structure, electrical, and optical properties of the films were investigated in detail. X-ray diffraction results show that the cell volume of the films reduces gradually with increasing oxygen pressure while preserving the epitaxial characteristic. X-ray photoelectron spectroscopy analysis confirms the Nb5+ oxidation state in the SSNO films. Hall-effect measurements were performed and the film prepared at 0.2 Pa with the 780 °C substrate temperature exhibits the lowest room-temperature resistivity of 31.3 mΩcm and Hall mobility of 3.31 cm2/Vs with a carrier concentration at 6.03 × 1019/cm3. Temperature-dependent resistivity of this sample displays metal-semiconductor transition and is explained mainly by electron-electron effects. Optical transparency of the films is more than 70% in the wavelength range from 600 to 1800 nm. The band gaps increase from 4.35 to 4.90 eV for the indirect gap and 4.82 to 5.29 eV for the direct by lowering oxygen pressure from 20 to 1 × 10−3 Pa, which can be interpreted by Burstein-Moss effect and oxygen vacancies generated in the high vacuum. [ABSTRACT FROM AUTHOR]