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•A novel Co3O4 architecture was created with a well-defined porous cubic feature.•The Co3O4 crystals were directly served as the ink to screen-print a biosensor microchip.•The chip ...shows ultrahigh glutamate sensitivity with excellent usage stability for more than 300-times test in 30 days.
Although l-glutamate is an important biological analyte for the clinic diagnosis and food industry, rare capable glutamate biosensor has been developed in the practical detection. The electrochemical biosensor is an advanced technique due to its on-site and real-time concentration recognition, however, the unsatisfactory performance in the glutamate detection blocks its production transfer. In this work, we proposed a novel screen-printed glutamate biosensor chip fabricated in large-scale through designing a porous nanocubic Co3O4. This material is prepared via a facile thermal oxidation strategy by using the cobalt hexacyanoferrate (CoHCF) as a precursor to construct its regular geometric morphology. The obtained Co3O4 crystal is of both regular nanocubic outline and abundant interconnected pores to generate high electrocatalysis on the glutamate enzymatic oxidation. It was directly served as the screen-printing ink to fabricate a microchip which integrated all three-electrode components. In detection, with loading a small amount of glutamate oxidation, this biosensor chip can still exhibit a high sensitivity of 20.12 μA mM−1 cm−2, as well as a wide linear range from 10 to 600 μM and a low LOD = 10 μM. Besides, under a very low working potential of -0.2 V. Moreover, the biosensor chip possesses an excellent anti-interference ability and usage stability to withstand more than 300 tests in 30 days.
To deal with corner separation in high-load axial compressors, this paper proposes a new end wall contouring method aimed at controlling the end wall secondary flow in more than one local area, ...generating a geometry with fewer control variables that is applicable for multiple working conditions. The new method defines more than one surface unit function, with different effects on end wall secondary flow. Then, the geometry of these surface unit functions will be superposed to generate the end wall contouring, to combine their flow control effects. After applying the new method to a bi-objective optimization design process, with 15 design variables aimed at minimizing the loss of cascade at 0° and 4° incidence, the optimal design reduces the total pressure loss of the high-load cascade by 5% under the former incidence and by 3% under the latter. The most effective design rule is constructing an end wall surface with the rising suction side and sinking pressure side in the blade channel, while locally raising the SS corner with a gentle upstream slope. According to the analysis, the design variables of the new method show an intuitive influence on the variation of end wall geometry and the movement of secondary flow. The corner separation has been effectively suppressed, with fewer control variables than before. It, thus, indicates the advantage of the newly developed end wall contouring method compared with previous studies.
•A novel Ag@PB core-shell nanocube composite was designed as the biosensing materials.•Core-shell nanostructure enhanced synergetic effects of Ag and PB to improve performance of chip.•An accurate, ...portable and ultrasensitive flexible biosensing chip was printed by using the ink.•The chip shows ultrahigh sensitive detections of H2O2 and glucose with the wide linear range and LOD.•This chip can also achieve the accurate and fast recognition of blood sugar in the serum.
A real-time, portable, ultrahigh sensitive and selective biosensing chip is desired to satisfy the urgent requirement of the practical application. In this study, a novel three-dimensional (3D) silver nanocubes@Prussian blue (AgNCs@PB) core-shell material has been designed to develop an ultrasensitive biosensing chip by a seed-mediated interfacial assembly approach. A Prussian blue (PB) shell with the 30.12 nm thickness was precisely controlled to in-situ grow on the whole surface of AgNCs through the electrostatic interaction. A flexible and portable biosensing chip was printed and functionalized by using this 3D AgNCs@PB biosensing material to integrate the superior conductivity from AgNCs and electrocatalytic activity from PB for the remarkable performance enhancement. This chip can realize about four times increase of the sensitivity compared with the other PB based screen-printing electrode (SPE), as well as a very wide linear response from 0.01 mM to 1.3 mM and an ultralow limit of detection (LOD) of 0.005 mM for the glucose detection with an excellent anti-interference ability. Especially, it also presented an ultra-accurate detection of the blood sugar in a real serum with a low deviation (3.37%).
The felsic volcanic rocks in orogenic belts are vital probes to understand the tectonic evolution and continental crust growth. Here, we present a comprehensive study on the zircon U–Pb ...geochronology, whole-rock geochemistry, and zircon Lu-Hf isotopes of Early felsic volcanic rocks from the Hongshuichuan Formation, East Kunlun Orogen, Northern Tibet, aiming to explore their petrogenesis and implications for the Paleo-Tethyan orogeny and crustal evolution. The studied felsic volcanics comprise rhyolite porphyry and rhyolite, exhibiting coeval zircon U–Pb ages of ca. 247–251 Ma. Rhyolite porphyries show metaluminous to peraluminous nature (A/CNK = 0.88–1.24) with high SiO2 contents (72.1–78.9 wt%) and moderate Mg# values (22–40), and they display enrichment of LREE with (La/Yb)N ratios of 6.02–17.9 and depletion of high field strength elements. In comparison, the rhyolites are strongly peraluminous (A/CNK = 1.09–1.74) with high SiO2 contents (71.7–74.3 wt%) and high Mg# values (43–52) and are also enriched in LREE ((La/Yb)N of 6.65–18.4) and depleted in HFSE (e.g., Nb, Ta, Ti). Combining with their different zircon Lu-Hf isotopes, i.e., enriched isotopes for the rhyolite porphyries (εHf(t) = −7.3 to −3.8) and depleted Hf isotopes for the rhyolites (ɛHf = −0.6 to +3.0), we interpret that the studied rhyolite porphyries and rhyolites were derived by partial melting of Mesoproterozoic metagreywacke sources followed by plagioclase-dominated fractional crystallization, but the latter shows the significant contribution of crust–mantle magma mixing. The mixed mantle-derived magma comes from an enriched lithospheric mantle source that had been metasomatized by subduction-related fluids. Combining with other geological evidence, we propose that the studied Early Triassic felsic volcanic rocks were formed in a subduction arc setting, and the reworking of ancient continental crust with crust–mantle magma mixing is the major mechanism of crustal evolution in the East Kunlun Paleo-Tethyan orogenic belt.
There is a magmatic lull period in the East Kunlun orogen (EKO) during the Jurassic to the Cretaceous. However, due to the lack of records of magmatic activity restricts our understanding of the late ...Mesozoic magmatic-tectonic evolution of the EKO. Herein, an integrated study of geochronology, whole-rock geochemistry and Sr-Nd isotopes were conducted for the Cretaceous mafic dykes in the EKO, Northern Tibet Plateau, to reveal their petrogenesis and geodynamic implications. LA-ICP-MS Zircon U-Pb dating reveals that the studied mafic dykes comprising diabase and diabase porphyry emplaced at ca. 80.9 ± 0.8 Ma. The Cretaceous mafic dykes have low contents of SiO2 (46.36 wt.%~47.40 wt.%) but high contents of MgO (6.79 wt.%~7.38 wt.%), TiO2 (1.91 wt.%~2.13 wt.%), Nb (12.4~18.3 ppm) and Nb/U ratio (31~39), resembling Nb-enriched mafic dykes. They exhibit chondrite-normalized rare earth element (REE) and primitive mantle-normalized trace element patterns, remarkably similar but not identical to the oceanic island basalts (OIB). The moderate REE fractionation ((La/Yb)N = 3.55~5.37), weak negative Eu anomalies (δEu = 0.87~0.97) and relative enrichment of Rb, Ba, K, as well as high contents of Cr and Ni and slightly depleted Sr-Nd isotopes (εNd(t) = −0.18~1.33), suggest that the studied dykes originate from a partial melting of spinel lherzolite and a little of garnet which was previously modified by subducted sediments. Combined with other evidence, we propose that the studied Cretaceous Nb-enriched mafic dykes in the Northern Tibet Plateau were formed in the intraplate setting, which may be a partial melting of the enriched mantle in the lower lithosphere caused by the activity of the East Kunlun strike-slip fault.
To further control corner separation in high-load axial compressors, this study proposes a new end wall contouring method. It defines multiple standard “surface units” with particular flow control ...effects and then applies a linear combination, finally forming the geometry of the end wall surface. Based on design experiences, three different end wall contouring cases are generated and calculated on a high-load compressor cascade in the first step. The results show that the new method achieves a clear and intuitive influence on the end wall geometry, with a proper number of design variables, and can effectively combine variables with the development of secondary flow. In the second step, the new method was applied to an axial compressor, with an improvement in the design variables. Although the end wall contouring only improved the efficiency of the compressor stage on the right part of its operating map, the experimental results of the flow field show that the corner separation and end wall loss are suppressed at multiple inflow conditions. The results thus verified the practical effect of the newly developed end wall contouring method.
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