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•A ultra-facile technique is reported for synthesis of cobalt deficient Co(OH)2 nanosheets.•Vco-Co(OH)2 had large surface area, low impedance, high heterogeneous rate constant than ...that of defect-free Co(OH)2.•Vco-Co(OH)2-based disposable sensor shows excellent electrochemical sensing performance for Glucose and l-Cysteine.
Engineering of nanomaterials with atomic defects has becoming an effective way to boost the sensitivity of the electrochemical biosensors but challenging. Herein, a rational, facile and in-situ strategy has been reported to obtain cobalt hydroxide nanosheets (VCo-Co(OH)2) with abundant cobalt vacancies. The cobalt defects greatly enriched electroactive sites and charge transfer rates, thereby delivered excellent electrocatalytic oxidation performance towards glucose and l-cysteine. The dynamic range and low limit of detection of glucose at VCo-Co(OH)2 electrodes were found as 0.4 μM–8.23 mM and 295 nM respectively. Besides, VCo-Co(OH)2 electrodes accurately sensed the l-cysteine with lowest detection limit (76.5 nM), and broad linear sensing range (200 nM-1.94 mM), which are better than the performance of defect-free Co(OH)2 electrodes, evidence that construction of cobalt vacancy significantly boosted the electrocatalysis. Importantly, fabricated sensors had excellent interference immunity against the many biomolecules, owns good stability and reproducibility. Present work not only proposed a novel and simplistic approach to prepare the metal hydroxides with copious metal cation vacancies for electrocatalysis but also provides economical, precise, high-sensitive and disposable biosensors for clinical analysis glucose and l-cysteine.
•The DGGB consists of a volcano-sedimentary assemblage intruded by TTGs and diorites.•A volcano-sedimentary assemblage represents a fore-arc subduction-accretion complex.•Amphibolites formed in a ...fore-arc setting and yield a 2.5Ga metamorphism age.•TTGs and diorites formed in an arc-related setting and yield a 2.5Ga intrusion age.•A 2.5Ga subduction-accretion-collision event is proposed in the Southern NCC.
The Dengfeng granite-greenstone belt (DGGB), located in the southern segment of the Central Orogenic Belt (COB) of the North China Craton (NCC), consists of a volcano-sedimentary assemblage, intruded by tonalite, trondhjemite, granodiorite (TTG suite), diorite, granites and late mafic dikes. The volcano-sedimentary assemblage in the DGGB mainly consists of tectonically imbricated basaltic amphibolites, meta-gabbroic rocks with minor ultramafic rocks, and metagreywacke, marble and quartzite, consistent with characterisitics of typical Phanerozoic subduction-accretion complexes. The basaltic amphibolites yield a metamorphic zircon 207Pb/206Pb age of 2507±26 Ma, interpreted to represent the peak age of amphibolite facies metamorphism that took place during subduction/accretion of the basaltic protolith. The basaltic amphibolites are characterized by a tholeiitic affinity, and flat LREE patterns with minor negative Nb and Zr anomalies. Based on mixed MORB- and arc-affinities, the basaltic amphibolites in the DGGB are interpreted to have formed in a fore-arc tectonic setting. One late potassic granite dike cutting across the fabrics of the volcano-sedimentary assemblage yields an intrusion age of 2492±35 Ma, constraining the minimum deformation age for tectonic assembly of the package. The TTG gneisses and diorites intruded the western margin and the center of the subduction-accretion complex, respectively. One TTG sample and one diorite sample yield igneous zircon 207Pb/206Pb ages of 2514±26 Ma and 2518±36 Ma, respectively, constraining their intrusion ages. The TTG gneisses display high ratios of (La/Yb)cn and Sr/Y, and depletion in HFSE with negative Nb, Ta and Ti anomalies, consistent with those of typical Archean TTGs. The TTG gneisses are therefore considered to be generated from partial melting of a shallowly subducting oceanic slab and/or accreted arc amphibolites. The diorites have high concentrations of MgO (2.89–6.05wt.%), Ni (148–178ppm) and Cr (85.7–120.6ppm), and highly fractionated REE patterns and are depleted in HFSEs with negative Nb, Ta, Zr, Hf and Ti anomalies. We suggest that the high-Mg diorites in the DGGB may have been derived from a hydrated mantle wedge which was previously metasomatized by subduction-derived melts and/or fluids. Collectively, a Neoarchean subduction-accretion-collision event is therefore proposed to have generated the DGGB. The volcano-sedimentary assemblage in the DGGB represents a fore-arc subduction-accretion complex, which is interpreted to be related to the suture zone of ca. 2.5 Ga arc-continent collision between a TTG-dominated arc terrane in the COB and the Eastern Block of the NCC. We further propose a long N-S striking Neoarchean suture zone occurring in the eastern margin of the COB mainly consists of the ca. 2.5 Ga subduction-accretion complex in the DGGB to the south, the ca. 2.5 Ga mélange belt in the Zanhuang Complex in the central, and the ca. 2.5 Ga ophiolitic mélange belt in the Zunhua-Dongwanzi structural belt to the north, which separate an arc terrane in the COB from the Eastern Block of the NCC.
This paper presents an efficient and compact MATLAB code for three-dimensional stress-based sensitivity analysis. The 146 lines code includes the finite element analysis and p-norm stress sensitivity ...analysis based on the adjoint method. The 3D sensitivity analysis for p-norm global stress measure is derived and explained in detail accompanied by corresponding MATLAB code. The correctness of the analytical sensitivity is verified by comparison with finite difference approximation. The nonlinear optimization solver is chosen as the Method of moving asymptotes (MMA). Three typical volume-constrained stress minimization problems are presented to verify the effectiveness of sensitivity analysis code. The MATLAB code presented in this paper can be extended to resolve different stress related 3D topology optimization problems. The complete program for sensitivity analysis is given in the Appendix and is intended for educational purposes. MATLAB code is additionally provided in electronic supplementary material for a simple cantilever beam optimization.
Defects are generally regarded to have negative impacts on carrier recombination, charge transport, and ion migration in materials, which thus lower the efficiency, speed, and stability of ...optoelectronic devices. Meanwhile, lots of efforts which focused on minimizing defects have greatly improved the performances of devices. Then, can defects be positive in optoelectronic devices? Herein, relying on in‐depth understanding of defect‐associated effects in semiconductors, trapping of photo‐generated carriers by defects is applied to enlarge photoconductive gain in photodetection. Therefore, the record photoconductive gain, gain‐bandwidth product, and detection limit are achieved in this photodetector. Exceeding the general concept that defects are harmful, a new view that the defects can be positive in photodetection is identified, which may guide to design high‐performance photodetectors.
Relying on in‐depth understanding of defect‐associated effects in semiconductors, trapping of photo‐generated carriers by defects is applied to enlarge photoconductive and the record performances are achieved in this photodetector. Exceeding the general concept that defects are harmful, a new view that defects are positive in optoelectronics is identified, which will guide us to design high‐performance devices in the future.
Abstract
Ammonia and nitric acid are two key platform chemicals to introduce nitrogen atoms into organic molecules in chemical industry. Indeed, nitric acid is mostly produced through the oxidation ...of ammonia. The ideal nitrogenation would involve direct use of dinitrogen (N
2
) as a N source to construct N-containing organic molecules. Herein, we report an example of direct catalytic nitrogenation to afford valuable diarylamines, triarylamines, and N-heterocycles from easily available organohalides using dinitrogen (N
2
) as the nitrogen source in a one-pot/two-step protocol. With this method,
15
N atoms are easily incorporated into organic molecules. Structurally diversified polyanilines are also generated in one pot, showing great potential for materials chemistry. In this protocol, lithium nitride, generated in situ with the use of lithium as a reductant, is confirmed as a key intermediate. This chemistry provides an alternative pathway for catalytic nitrogenation to synthesize highly valuable N-containing chemicals from dinitrogen.
High-resolution TEM (HRTEM) is a powerful tool for structure characterization. However, methylammonium lead iodide (MAPbI3) perovskite is highly sensitive to electron beams and easily decomposes into ...lead iodide (PbI2). Misidentifications, such as PbI2 being incorrectly labeled as perovskite, are widely present in HRTEM characterization and would negatively affect the development of perovskite research field. Here misidentifications in MAPbI3 perovskite are summarized, classified, and corrected based on low-dose imaging and electron diffraction (ED) simulations. Corresponding crystallographic parameters of intrinsic tetragonal MAPbI3 and the confusable hexagonal PbI2 are presented unambiguously. Finally, the method of proper phase identification and some strategies to control the radiation damage in HRTEM are provided. This warning paves the way to avoid future misinterpretations in HRTEM characterization of perovskite and other electron beam-sensitive materials.
Laterally extensive belts of mélange characterize Phanerozoic convergent plate margins, but are rare in Archean terranes. We document a late Archean mélange in the Zanhuang Massif of the North China ...Craton (NCC). The Zanhuang mélange separates a passive margin to foreland basin sequence developed on the western edge of the Eastern Block of the NCC from an arc terrane consisting of trondhjemitic, tonalitic and granodioritic (TTG) gneisses in the Central Orogenic Belt (COB) of the NCC. The mélange belt contains a structurally complex tectonic mixture of metapelites, metapsammites, marbles and quartzites mixed with exotic tectonic blocks of ultramafic and metagabbroic rocks, metabasalts that locally include relict pillow structures, and TTG gneisses. All units in the mélange have been intruded by mafic dikes that were subsequently deformed, and are now preserved as garnet–amphibolite boudins. We interpret the mélange to mark the suture zone between the Eastern Block and the arc terrane in the COB. Field relationships and geochemistry suggest that the exotic ultramafic–metagabbroic–metabasaltic blocks are possible slivers of an intra-oceanic arc or fore-arc ophiolite incorporated into the mélange during the arc–continent collision process. A circa 2.5Ga granitic pluton intrudes the mélange and undeformed circa 2.5Ga pegmatites cut the mélange. Tectonic models for the evolution of the COB are varied, but include models that favor collision at 2.5Ga, 2.1Ga, and 1.8Ga. This work shows clearly, from field structural relationships and geochronology, that the first collision must have occurred prior to 2.5Ga, consistent with late Archean suturing of the western margin of the Eastern Block with an arc terrane (Fuping terrane) during an arc–continent collision. The presence of an Archean mélange with exotic blocks in a suture zone between an Archean arc and continental margin is clear evidence for the operation of plate tectonics at circa 2.5Ga.
•We document a late Archean mélange in the North China Craton (NCC).•The mélange formed during accretion of an arc to the Eastern Block of the NCC.•Results show modern plate tectonics and accretionary processes operated at 2.5Ga.
Beginning in 2013, China's photovoltaic (PV) market-development strategy witnessed a series of policy changes aimed at making distributed-generation PV (DG PV) development an equal priority with ...large-scale PV development. This article reviews the DG PV policy changes since 2013 and examines their effect on China's domestic DG PV market. Based on a 2014 survey of DG PV market and policy participants, we present cost and time breakdowns for installing DG PV projects in China, and we identify the main barriers to DG PV installation. We also use a cash flow model to determine the relative economic attractiveness of DG PV in several eastern provinces in China. The main factors constraining DG PV deployment in China include financial barriers resulting from the structure of the self-consumption feed-in tariff (FIT), ambivalence about DG PV within grid companies, complicated ownership structures for buildings/rooftops/businesses, and the inherent time lag in policy implementation from the central government to provincial and local governments. We conclude with policy implications and suggestions in the context of DG PV policy changes the Chinese government implemented in September 2014.
•We review China's distributed PV market development and policy changes since 2013.•We present cost and time requirements for installing distributed PV in China.•We conduct IRR analysis of distributed PV under different policy frameworks.•We identify barriers to China's distributed PV, especially feed-in tariff barriers.
We report an experiment to test quantum interference, entanglement, and nonlocality using two dissimilar photon sources, the Sun and a semiconductor quantum dot on the Earth, which are separated by ...∼150 million kilometers. By making the otherwise vastly distinct photons indistinguishable in all degrees of freedom, we observe time-resolved two-photon quantum interference with a raw visibility of 0.796(17), well above the 0.5 classical limit, providing unambiguous evidence of the quantum nature of thermal light. Further, using the photons with no common history, we demonstrate postselected two-photon entanglement with a state fidelity of 0.826(24) and a violation of Bell inequality by 2.20(6). The experiment can be further extended to a larger scale using photons from distant stars and open a new route to quantum optics experiments at an astronomical scale.
Although a massive research has been devoted on the exploration of noble metal–based nanozyme, less progress has been made in the investigation of palladium (Pd) nanozyme and the interaction between ...ions and Pd nanozyme. In this study, a new type of Pd nanozyme was prepared by a facile one-pot approach by using carboxylated chitosan as the stabilizer. Owing to the synergistic effect of carboxylated chitosan stabilized Pd nanoparticles (CC-PdNPs) can effectively catalyze the H
2
O
2
-mediated oxidation of 3,3′,5,5′-tetramethylbenzidine sulfate (TMB) accompanied by a blue color change (oxidized TMB), indicating the peroxidase-like activity of CC-PdNPs. Furthermore, the Michaelis-Menten constants and catalytic stability of CC-PdNPs render them suitable for environmental analysis and bio-detection. Here, we found that while introducing the iodine ions (I
−
) into the reaction medium, the peroxidase-like activity of CC-PdNPs has been rapidly and effectively inhibited through the formation of Pd-I bond; thus, the active sites of PdNPs can be blocked by I
−
. Based on this specific inhibition by I
−
, a facile colorimetric assay has been performed for the detection of I
−
with an extremely low limit of detection (0.19 nM). Furthermore, the practicality of the proposed sensor also has been demonstrated in tap water, and the satisfactory recoveries were obtained. Our study not only demonstrated a novel Pd–based nanozyme but also provided guidance for I
−
sensing for environmental analysis, food inspection, and bio-detection.
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