In this paper, a fiber-optic surface plasmon resonance (SPR) biosensor is presented, in which a sheet of graphene acting as a sensing layer is coated around the gold film. A theoretical study of the ...proposed fiber-optic biosensor has been carried out by applying four-layer modal, which shows that by incorporating a graphene sensing layer, the sensitivity of the proposed SPR fiber biosensor can be greatly enhanced than the conventional gold film SPR fiber sensors. The relationship between resonance wavelengths and sensitivity of the proposed graphene sensing layer-based SPR fiber biosensor with the number of sensing layer has also been studied.
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•Biofertilizer reduced NH3 emission in farmland by 44%.•Biofertilizer decreased the conversion of fertilizer nitrogen to NH4+-N.•Biofertilizer increased the abundance of bacterial ...amoA and comammox amoA.•Biofertilizer shifted the soil nitrogen cycling microbiomes.
Excessive ammonia (NH3) emitted from nitrogen fertilizer application in farmland have caused serious disturbance to global environment, including reduction of visibility, formation of regional haze, and increase of nitrogen deposition. Application of biofertilizer has been considered as an effective approach for soil improvement and agriculture sustainability. In this study, a field experiment was conducted to evaluate the potential of B. subtilis biofertilizer on mitigating NH3 volatilization and to investigate the underlying mechanisms. Compared with organic fertilizer, the incorporation of B. subtilis biofertilizer reduced NH3 volatilization by up to 44%. Moreover, the application of B. subtilis biofertilizer reduced the abundance of ureC gene, and increased the abundance of functional genes (bacterial amoA and comammox amoA) and ammonia-oxidizing bacteria (AOB). This indicated that the conversion of fertilizer nitrogen to NH4+-N was decreased and the nitrification process was increased. In brief, the application of B. subtilis biofertilizer reduced the “source” and increased the “sink” of NH4+-N, thus reducing the retention of NH4+-N in alkaline soil, and mitigating NH3 volatilization. These results indicated that B. subtilis biofertilizer is an effective control strategy for agricultural NH3 emission, maintaining high crop yield and mitigating environmental disturbance.
We study the superconducting pairing correlations in the ground state of the doped Hubbard model—in its original form without hopping beyond nearest neighbor or other perturbing parameters—in two ...dimensions at intermediate to strong coupling and near optimal doping. The nature of such correlations has been a central question ever since the discovery of cuprate high-temperature superconductors. Despite unprecedented effort and tremendous progress in understanding the properties of this fundamental model, a definitive answer to whether the ground state is superconducting in the parameter regime most relevant to cuprates has proved exceedingly difficult to establish. In this work, we employ two complementary, state-of-the-art, many-body computational methods—constrained-path (CP) auxiliary-field quantum Monte Carlo (AFQMC) and density matrix renormalization group (DMRG) methods—deploying the most recent algorithmic advances in each. Systematic and detailed comparisons between the two methods are performed. The DMRG is extremely reliable on small width cylinders, where we use it to validate the AFQMC. The AFQMC is then used to study wide systems as well as fully periodic systems, to establish that we have reached the thermodynamic limit. The ground state is found to be nonsuperconducting in the moderate to strong coupling regime in the vicinity of optimal hole doping.
Competing inhomogeneous orders are a central feature of correlated electron materials, including the high-temperature superconductors. The two-dimensional Hubbard model serves as the canonical ...microscopic physical model for such systems. Multiple orders have been proposed in the underdoped part of the phase diagram, which corresponds to a regime of maximum numerical difficulty. By combining the latest numerical methods in exhaustive simulations, we uncover the ordering in the underdoped ground state. We find a stripe order that has a highly compressible wavelength on an energy scale of a few kelvin, with wavelength fluctuations coupled to pairing order. The favored filled stripe order is different from that seen in real materials. Our results demonstrate the power of modern numerical methods to solve microscopic models, even in challenging settings.
In the present study, a new turbomolecular pump (TMP) performance prediction algorithm is proposed according to the variable surface combined blade row (VSCBR) geometric model. The simulation ...calculation program is designed to perform structural optimization and flow field analysis. Research on the pumping performance of the traditional straight blade row (TSBR) indicates that when the blade velocity ratio is greater than 1, the increase in the pumping speed and compression ratio of the TMP gradually tends to stabilize. Response surface methodology is used to optimize the structural parameters of the first four stages of the combined blade row. The optimized VSCBR increases the pumping speed by 18.2% compared to that of the TSBR. The flow field analysis based on the optimized VSCBR shows that gas molecules reaching the rear blades are likely to approach the outlet, and the proportion of gas molecules in this region exceeds 50%. Therefore, the blades we designed should be conducive to additional gas molecules reaching the outlet.
We describe an algorithm to reduce the cost of auxiliary-field quantum Monte Carlo (AFQMC) calculations for the electronic structure problem. The technique uses a nested low-rank factorization of the ...electron repulsion integral (ERI). While the cost of conventional AFQMC calculations in Gaussian bases scales as O ( N 4 ) , where N is the size of the basis, we show that ground-state energies can be computed through tensor decomposition with reduced memory requirements and subquartic scaling. The algorithm is applied to hydrogen chains and square grids, water clusters, and hexagonal BN. In all cases, we observe significant memory savings and, for larger systems, reduced, subquartic simulation time.
•A novel sintered copper mesh wick was developed for improving the performance of ultra-thin heat pipes.•Capillary force of the deposited wick structures was experimentally examined by comparing with ...normal mesh wicks.•The capillary force of the deposited wick structures was larger than that of a normal wick.
A novel sintered copper mesh wick, fabricated by weaving, chemical deposition, and sintering, was developed for improving the performance of ultra-thin heat pipes. Capillary force of the deposited wick structures was experimentally examined by comparing with normal mesh wicks. In this study, the sintering process was used to enhance the adhesive strength of the surface structure. Capillary rate-of-rise tests with ethanol and acetone were performed to characterize the capillary force of wick structures. An infrared (IR) thermal imaging method was utilized to monitor the capillary rise processes. The effects of deposition time and sintering temperature on the capillary force were investigated. Test results indicate that the capillary force of the deposited wick structures was larger than that of a normal wick, and the rising velocity and capillary rise height increased as the deposition time increased from 5 to 20min. The sintering process maintains good integrity of the surface microstructures even after being subjected to ultrasonic vibrations for 2min, and also has a great influence on the capillary force of the deposited samples. The deposited wicks can achieve optimum operating efficiency by choosing deposition time of about 15min and a sintering temperature of around 500°C.
The sign problem is a major obstacle in quantum Monte Carlo simulations for many-body fermion systems. We examine this problem with a new perspective based on the Majorana reflection positivity and ...Majorana Kramers positivity. Two sufficient conditions are proven for the absence of the fermion sign problem. Our proof provides a unified description for all the interacting lattice fermion models previously known to be free of the sign problem based on the auxiliary field quantum Monte Carlo method. It also allows us to identify a number of new sign-problem-free interacting fermion models including, but not limited to, lattice fermion models with repulsive interactions but without particle-hole symmetry, and interacting topological insulators with spin-flip terms.
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