A New Machine Learning Approach Based on Range Corrected Deep Potential Model for Efficient Vibrational Frequency Computation

Vibrational spectrum simulation, as an ensemble average result, can be very time consuming when using high accuracy methods. Here, we introduce a new machine learning approach based on the range corrected deep potential (DPRc) model to improve computing efficiency. The approach was applied to computing \ch{C=O} stretching vibrational frequency shifts of formic acid-water solution. DPRc is adapted for frequency shift calculation. The system was divided into ``probe region'' and ``solvent region'' by atom. Three kinds of ``probe region'' were tested: single atom with atomic contribution correction, a single atom, and a single molecule. All data sets were prepared using by Quantum Vibration Perturbation (QVP) approach. The deep potential (DP) model was also adapted for frequency shift calculation for comparison, and different interaction cut-off radii were tested. The single molecule ``probe region'' results show the best accuracy, running roughly ten times faster than regular DP, while reducing the training time by a factor of about four, making it fully applicable in practice. The results show that dropping information of interaction distances between solvent atoms can significantly increase computing and training efficiency while ensuring little loss of accuracy. The protocol is practical, easy to apply, and extendable to calculating other physical quantities

Volterra Series identification Based on State Transition Algorithm with Orthogonal Transformation

A Volterra kernel identification method based on state transition algorithm with orthogonal transformation (called OTSTA) was proposed to solve the hard problem in identifying Volterra kernels of nonlinear systems. Firstly, the population with chaotic sequences was initialized by using chaotic strategy. Then the orthogonal transformation was used to finish the mutation operator of the selected individual. OTSTA was used on the identification of Volterra series, and compared with particle swarm optimization (called PSO) and state transition algorithm (STA). The simulation results showed that OTSTA has better identification precision and convergence than PSO and STA under non-noise interference. And when there is noise, the identification precision, convergence and anti-interference of OTSTA are also superior to PSO and STA

High-responsivity vertical-illumination Si/Ge uni-traveling-carrier photodiodes based on silicon-on-insulator substrate

Si/Ge uni-traveling carrier photodiodes exhibit higher output current when space-charge effects are overcome and thermal effects are suppressed, which is highly beneficial for increasing the dynamic range of various microwave photonic systems and simplifying high-bit-rate digital receivers in different applications. From the point of view of packaging, detectors with vertical-illumination configuration can be easily handled by pick-and-place tools and are a popular choice for making photo-receiver modules. However, vertical-illumination Si/Ge uni-traveling carrier (UTC) devices suffer from inter-constraint between high speed and high responsivity. Here, we report a high responsivity vertical-illumination Si/Ge UTC photodiode based on a silicon-on-insulator substrate. The maximum absorption efficiency of the devices was 2.4 times greater than the silicon substrate owing to constructive interference. The Si/Ge UTC photodiode was successfully fabricated and had a dominant responsivity at 1550 nm of 0.18 A/W, a 50% improvement even with a 25% thinner Ge absorption layer.Comment: 5pages,2figure

Anti-hyperprolactinemia mechanism of Radix bupleuri extract in rats

Purpose: To determine the mechanism underlying the anti-hyperprolactinemia effects of Radix bupleuri extract (RBE) in rats.Methods: Rats were divided into six groups (n=10 each group): healthy controls, untreated hyperprolactinemic rats, hyperprolactinemic rats treated with bromocriptine (0.6 mg/kg), and hyperprolactinemic rats treated with RBE (4.8, 9.6, or 19.2 g/kg). After 30 days, hypothalamic protein levels of dopamine D2 receptor, protein kinase A (PKA), and cyclic adenosine monophosphate (cAMP) were determined.Results: Dopamine D2 receptor levels were lower in untreated hyperprolactinemic rats than in healthy controls (p < 0.01), but this decrease was attenuated by RBE (p < 0.05). Elevated PKA levels in untreated hyperprolactinemic rats (0.61 ± 0.04 μg/ml, p < 0.01) were decreased by RBE (4.8 g/kg, 0.42 ± 0.03 μg/ml, p < 0.05; 9.6 g/kg, 0.33 ± 0.02 μg/ml, p < 0.01; 19.2 g/kg, 0.27 ± 0.03 μg/ml, p < 0.01). Similarly, elevated cAMP levels in hyperprolactinemic rats (2.4 ± 0.4 ng/ml) were decreased by RBE (4.8 g/kg, 1.8 ± 0.3 ng/ml, p < 0.05; 9.6 g/kg, 1.5 ± 0.3 ng/ml, p < 0.01; 19.2 g/kg, 1.2 ± 0.2 ng/ml, p < 0.01).Conclusions: RBE anti-hyperprolactinemia activity is mediated by dopamine D2 receptor signaling via the cAMP/PKA pathway.Keywords: Hyperprolactinemia, Radix bupleuri, Dopamine D2 receptor, cAMP/PK

Oriented Graphene Nanoribbons Embedded in Hexagonal Boron Nitride Trenches

Graphene nanoribbons (GNRs) are ultra-narrow strips of graphene that have the potential to be used in high-performance graphene-based semiconductor electronics. However, controlled growth of GNRs on dielectric substrates remains a challenge. Here, we report the successful growth of GNRs directly on hexagonal boron nitride substrates with smooth edges and controllable widths using chemical vapour deposition. The approach is based on a type of template growth that allows for the in-plane epitaxy of mono-layered GNRs in nano-trenches on hexagonal boron nitride with edges following a zigzag direction. The embedded GNR channels show excellent electronic properties, even at room temperature. Such in-plane hetero-integration of GNRs, which is compatible with integrated circuit processing, creates a gapped channel with a width of a few benzene rings, enabling the development of digital integrated circuitry based on GNRs.Comment: 32 pages, 4 figures, Supplementary informatio

Compressive Property Comparisons Between Laser Engineered Net Shaping of In Situ TiBw-TMCs and Cp-Ti Materials

Titanium (Ti) and its alloys are widely used in chemical, astronautical, and biomedical industries. However, their poor load endurance properties affect their fields of applications especially under severe loading conditions. To enhance these properties, TiBw reinforcement was synthesized by in situ chemical reaction between elemental Ti and boron. Strong interfacial bonding between TiBw reinforcement and Ti matrix was obtained due to the in situ chemical reaction. Owing to its capability of producing difficult-to-machine bulk composites with uniform properties, laser engineered net shaping (LENS) technique was utilized to fabricate TiBw reinforced Ti matrix bulk composites. Few researches have been reported on these three-dimensional metal based bulk composites by using LENS. In this work, effects of TiBw reinforcement and laser power on compressive properties were investigated. The microstructures of the fabricated parts were observed and analyzed by using scanning electron microscopy.Mechanical Engineerin

Direct evidence for active site-dependent formic acid electro-oxidation by topmost-surface atomic redistribution in a ternary PtPdCu electrocatalyst

The active site-dependent electrochemical formic acid oxidation was evidenced by the increased coverage of Pt in the topmost mixed PtPd alloy layer of ternary PtPdCu upon potential cycling, which demonstrated two catalytic pathways only in one catalyst owing to surface atomic redistribution in an acidic electrolyte environment