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The controllable modulation of the electronic properties of two-dimensional van der Waals (vdW) heterostructures is crucial for their applications in the future nanoelectronic and optoelectronic devices. In this paper, the electronic properties of a graphene/AlP heterostructure are theoretically studied by first-principles calculation. The results show that due to the weak vdW interaction between graphene and the AlP monolayer, both the Dirac semi-metallic properties of graphene and the semiconductivity properties of monolayer AlP are well retained. The graphene/AlP heterostructure forms a 0.41 eV p-type Schottky contact, and the barrier height and contact type can be successively controlled by the applied external electric field and vertical stress. When the applied electric field exceeds −0.5 V Å−1, the heterostructure interface changes from a p-type Schottky contact to an n-type Schottky contact. When the applied electric field exceeds 0.4 V Å−1 or the interlayer spacing is less than 3.1 Å, the interface contact type changes to Ohmic contact. These results indicate that the graphene/AlP heterostucture behaves as tunable Schottky barrier for potential applications in nano-devices.

Exploration of native microbes is a feasible way to develop microbial agents for ecological restoration. This study was aimed to explore the impact of Bacillus amyloliquefaciens PDR1 from karst adaptive plant on the activity of root plasma membrane H+-ATPase in Arabidopsis thaliana. A. thaliana was cultured in presence or absence of B. amyloliquefaciens PDR1 and its effects on the growth were evaluated by measuring the taproot length and dry weight. The rhizosphere acidification capacity was detected by a pH indicator, a pH meter and non-invasive micro-test techniques (NMT). The nutrient uptake was performed using appropriate methods. A combination of transcriptome sequencing and real-time quantitative polymerase chain reaction (qRT-PCR) was used to measure the expression of functional genes that regulate the plasma membrane H+-ATPase activity in A. thaliana roots. Functional analysis was performed to understand how B. amyloliquefaciens regulates biological processes and metabolic pathways to strengthen A. thaliana resistance to alkaline stress. Here, we show that volatile organic compounds (VOCs) from B. amyloliquefaciens PDR1 promoted the growth and development of A. thaliana, enhanced the plasma membrane H+-ATPase activity, and affected ion absorption in Arabidopsis roots. Moreover, B. amyloliquefaciens PDR1 VOCs did not affect the expression of the gene coding for plasma membrane H+-ATPase, but affected the expression of genes regulating the activity of plasma membrane H+-ATPase. Our findings illuminate the mechanism by which B. amyloliquefaciens regulates the growth and alkaline stress resistance of A. thaliana, and lay a foundation for wide and efficient application for agricultural production and ecological protection.

Bacillus amyloliquefaciens is a non-pathogenic and plant growth-promoting rhizobacterium that enhances plant resistance to drought and diseases. Arabidopsis thaliana is a multipurpose model plant for exploring microorganism-plant interactions and a crucial vegetal tool for molecular research. Non-coding RNAs are RNA molecules involved in the regulation of various biological functions and constitute a research hotspot in the field of plant biology. In this study, the effect of B. amyloliquefaciens treatment on the resistance of A. thaliana to high calcium stress was analyzed. The transcriptome sequencing of A. thaliana roots under four treatment conditions was performed to screen differentially expressed lncRNAs, mRNAs and miRNAs. Functional analysis was also performed to understand the potential mechanism by which B. amyloliquefaciens-regulated lncRNAs, miRNAs and mRNAs affect the resistance of A. thaliana to high calcium stress. The results indicated that B. amyloliquefaciens treatment increased the resistance of A. thaliana to high calcium stress. A set of differentially expressed lncRNAs, mRNAs and miRNAs were screened between the high calcium and control group on one hand, and high calcium and high calcium + B. amyloliquefaciens groups on the other hand. Functional analysis indicated that the differentially expressed mRNAs and miRNA were involved in various biological functions and that transcriptional dysregulation caused by high calcium stress involves metabolic processes rather than defense responses. Conclusively, B. amyloliquefaciens may improve the resistance of A. thaliana to high calcium stress via a lncRNA-miRNA-mRNA regulatory network. These findings will contribute to the development of agriculture in karst regions with high calcium content.

Feature extraction is the core step to achieve speech recognition and is the key to the correctness of the speech recognition system. Feature extraction is to obtain effective information for speech recognition and remove redundant information. This article briefly describes the MFCC feature extraction process and optimizes the MFCC algorithm by changing the pre-emphasis parameter and the parameter addition method to adapt to the characteristics of short-word embedded speech recognition systems.