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Ab initio calculations on the anisotropic relaxation of a CuO/TiO2 surface under electric fields and the visible light absorption of these relaxed surfaces are reported. We compare the relaxation of the CuO/TiO2 surface under the electric fields in the direction of [001] or [010]. Fewer Cu–O bonds with highly coordinated Cu-ions are found in the CuO/TiO2 relaxed surface under the electric field in the [010] direction. The Cu–O bonds in the interface of the CuO/TiO2 surface led to an improved visible light absorption in the polarization direction of [001]. The CuO/TiO2 relaxed surface under the electric field in the [010] direction exhibits a more effective absorption of visible light. However, the electric field in the [001] direction induces more relaxation on the CuO/TiO2 surface, breaking the Cu–O bonds. This leads to the partial reduction of CuO to Cu2O on the CuO/TiO2 relaxed surface under the electric field in the [001] direction and inefficient absorption of visible light is observed for this surface. [ABSTRACT FROM AUTHOR]

• A physical model of kink in GaN devices was proposed. • This model describes the relation between kink and gate voltage. • It gives how the physical parameters of GaN devices affect the kink. • It can explain the kink phenomenon in experiments. The kink in the source-drain current of GaN devices has been not clarified. Based on the Maxwell-Boltzmann distribution of hot channel electrons, the generation of excess carriers in the L valleys of GaN and the origin of the kink had been modeled. This proposed model can predict how the kink depends on the gate voltage in experiments. It provides the reason why the kink partially disappears or disappears by sweeping the source-drain voltage from high voltage to low voltage, disappears under illumination, is more obvious at a lower temperature, and can be affected by different traps. All above experimental phenomena are associated with excess carriers in the L valleys of gain due to the hot channel carrier via internal transport. This model gives physical insight into how physical parameters of GaN devices affect the kink in the source-drain current. Thus, it can be used to optimize the physical parameters of GaN devices for reducing the kink. [ABSTRACT FROM AUTHOR]

The properties and behavior of a single Au atom supported anatase TiO2(001) surface are calculated using density functional theory (DFT) methods. The structures and energies of adsorbed single Au on an anatase TiO2(001) surface with surface oxygen vacancy, as well as subsurface oxygen vacancy, are systematically determined. Initially, the surface threefold coordinated oxygen vacancy adjacent to a single Au atom, rather than the surface two‐fold coordinated oxygen vacancy and subsurface threefold coordinated oxygen vacancy, results in more stability for anatase TiO2(001) surface with an Au adatom. Afterwards, the CO molecule is more strongly adsorbed on the single Au‐supported TiO2(001) surface with surface threefold coordinated oxygen vacancy when comparing to other structures. This is attributed to the more negatively charged Au single‐atom caused by a surface threefold coordinated oxygen vacancy presents concededly active for CO adsorption. The structures and energies of adsorbed single Au on anatase TiO2(001) surface with various oxygen vacancies are systematically addressed. The surface oxygen vacancy adjacent the adsorbed atomic Au increased the stability of atomic Au and further improved the adsorption of CO molecules. This is attributed to the oxygen vacancy above resulting in the presence of a charge reservoir in atomic Au. [ABSTRACT FROM AUTHOR]

• The order of thermotolerance of four rhododendrons was determined. • ROS and secondary metabolites played important roles in rhododendrons heat response. • TFs related to heat response of rhododendrons was screened out. • Abundant genomic information of rhododendrons was provided. Rhododendrons are prominent ornamental plants worldwide. The molecular mechanism of thermotolerance in the Rhododendron genus is still largely unknown. Here, R. molle, R. delavayi, R. irroratum , and R. decorum were selected to determine the molecular mechanism of the heat stress response in rhododendrons by transcriptomic studies. According to the heat injury index, the order of thermotolerance was R. molle > R. irroratum > R. decorum > R. delavayi. R. delavayi was sequenced with the reference genome, while other rhododendrons were sequenced without the reference genome. Two sequencing libraries of each rhododendron, namely one control and one heat stress-treated sample, were constructed for comparative transcriptomic analysis. In R. delavayi , 90.99% clean reads were mapped, and 86,621, 121,343, and 99,992 unigenes were identified in R. molle, R. irroratum , and R. decorum , respectively. Unigenes were annotated in the KEGG, GO, and Nr databases. According to the Nr annotation results, rhododendrons had a high gene similarity with Actinidia chinensis and Camellia sinensis. Between two sequencing libraries of R. molle, R. delavayi, R. irroratum , and R. decorum , 9017, 6916, 5243, and 11751 transcripts, respectively, were further identified as differentially expressed genes (DEGs). Transcription factor (TF) families enriched in DEGs mainly include ERF, bHLH, MYB, WRKY, and MYB_related, and several TFs were commonly regulated in all plants, such as BBR / BPC7, bZIP1, bZIP12, COL15, BBX22, ERF118-2, DREB2C, HsfC1, HSF8, LBD41, PHERES, RADIALIS-like 4, SPL14, SPL9 bHLH041, Dof5.4, ERF061 , and PTI6. The data obtained in this study can provide abundant genomic information for future research and help to clarify the molecular mechanisms of rhododendrons' heat stress response. [ABSTRACT FROM AUTHOR]

Cut rhododendron flowers have high ornamental value and are loved by consumers. It is important to clarify the senescence mechanism of cut rhododendron flowers to prolong their vase life. Transcriptome sequencing was used to investigate flower senescence in four stages of Rhododendron 'Hong Shanhu.' Using RNA sequencing, we generated approximately 100.17 Gb clean data and 173,502 annotated unigenes. Ethylene biosynthesis genes, ACOs , had different expression trends, and most ethylene signaling genes had low expression levels. The ethylene release rate and the activities of ACS and ACO were on the rise during cut flower development. The effects of 200 mg/L ethephon and 0.1 mM/L spermidine on vase life and fresh weight were limited. Most of the LEA and Dehydrin were upregulated with cut flower development and the fresh weight was decreased during fully flowering stage. Based on the different expression trends, differentially expressed genes were classified into 10 clusters. Cluster 2 showed significant upregulation between Z4 and Z3, suggesting that the genes in this cluster were upregulated, probably due to the senescence of cut flowers. The overall trend of Cluster 7 was positively correlated with the opening process of cut flowers. Cluster 9 had a peak at Z3, which indicated that the unigenes started the senescence process. bZIP53 , RAP2.4 , UIF1 , HAT5 , ILR3 , DEAR3 , SCL8 , TZF10 , MYB70 , ERF5 , ERF9 , and CBF1 had higher expression levels than the other transcription factors in these clusters, indicating that they are probably the key transcription factors involved in petal senescence. Our results indicated that 'Hong Shanhu' cut flowers were ethylene-insensitive, and their senescence was probably related to water stress. These results contribute to understanding the mechanism of senescence in cut rhododendron flowers. • 'Hong Shanhu' cut flowers are ethylene-insensitive. • Their senescence was probably related to water stress. • Most of LEA and dehydrin were upregulated during the aging process. • The ethylene release rate was on the rise throughout cut flower development. • The TFs involved in petal senescence were screened. [ABSTRACT FROM AUTHOR]

To illustrate the impacts of stress/strain effect on nano-scale transistor, a theoretical investigation of stress/strain and transition region of interface are presented in this paper. It is found that the residual stress changes from −1.8098 to 0.3159 GPa with Si layer thickness increasing. At the same time, Si Si average bond length reduces from 2.397 Α ο to 2.355 Α ο and finally approaches to 2.352 Α ο (the bond length of ideal silicon crystal). The further calculations demonstrate that the above mentioned changes also decrease surface potential. And the relative decrease in the surface potential becomes larger with the applied gate voltage decreasing especially when it is less than 1.5 V. Moreover, when the doping concentration is 1 × 10 19 cm −3 , the threshold voltage and subthreshold swing (SS) reduce from 2.9 V to 2 V and 551mV/dec to 198mV/dec respectively. It implies that we can get a better device performance by growing appropriate thickness of silicon. [ABSTRACT FROM AUTHOR]

The ab initio calculations about the properties of the interstitials doping in the rutile TiO2 and their impact on the transport coefficients are reported. As the doping of the Zr or Ti interstitials in the TiO2, the lattice Ti4+ ions acquire the excess electrons so reduced to the Ti3+ or Ti2+ ions. However, the Cu interstitials could not lose enough electrons to reduce the lattice Ti4+ ions. Furthermore, the Ti or Cu interstitials in the ZrO2 also are unable to promote the lattice Zr4+ ions to form the lattice Zr3+ or Zr2+ ions. The high transport coefficients are observed in the defected TiO2 with the Ti or Zr interstitials as the high concentration of the Ti3+ or Ti2+ ions. So, the Zr interstitials are the favorable choice for the extra-doping to improve the transport properties in the TiO2-based resistive random access memory. [ABSTRACT FROM AUTHOR]

[Display omitted] • Higher activation energy reduced CO catalytic property on Pt SAC. • Surface construction was on Pt3 atoms model but not on Pt SAC. • Worst tensile properties revealed weak P–O bonding in Pt3 atoms model. CuO layers coated with single noble metal atoms has been used in CO oxidation, but understanding of its mechanism is still ambiguous. A series of first-principles calculations were performed in this study to investigate the properties of a single Pt atom and triple Pt (Pt3) atoms supported on a CuO(1 1 0) layer on a Cu(1 1 0) substrate and their role in CO oxidation reactions. Calculations on the adsorption energies of O 2 and CO 2 as well as the subsequent energy evolution revealed that the Pt3 atoms were more active than the single Pt atom in CO oxidation. The catlyts surface with Pt3 atoms was reconstructed by CO oxidation, while no reconstruction phenomenon was found on the surface with the single Pt atom. Further, tensile properties along the [1 1 0] and [0 0 1] directions elucidated that the weak bonding between the Pt3 atoms and the substrate could result in the surface reconstruction. [ABSTRACT FROM AUTHOR]

The sintering deactivates CO oxidation in a single Au catalyst. Understanding the mechanism of sintering at a reduced atmosphere seems important for improving sintering resistance. Here, we employ the first principle calculations to evaluate the barrier energy of Au atoms on reduced rutile TiO 2 (110) surface and to demonstrate a favorable channel for their diffusion at an early stage in sintering. In the current DFT + U calculations, 16 structural configurations with oxygen vacancies and Au atoms are considered. This shows that Au atoms prefer to mobilize on fivefold-coordinated Ti (Ti 5c) row rather than moving perpendicularly from this Ti 5c row to a twofold-coordinated O (O 2c) row. We regard a trap center involving a complex of Au‒oxygen vacancy on an O 2c row as the initial nucleation site during sintering. It will capture the unstable Au atom on a Ti 5c row, and hence, a highly stable Au dimer would be produced as the primary nucleation pattern. • DFT + U calculations are performed on Au supported rutile TiO 2 (110) surface. • Calculated barrier energies are plotted based on16 structural configurations. • A V O adjacent an Au atom on an O 2c row attracted another Au atom on a Ti 5c row. • An Au dimer with the highest stability thereby appeared. • A complex of Au‒V O was concluded as an initial nucleation site during sintering. [ABSTRACT FROM AUTHOR]

Exploring the state of MoS 2 with different layers is a matter of interest in band gap and electrical engineering. In this paper, metal-oxide-semiconductor field-effect transistors based on MoS 2 are studied, with respect to the number of MoS 2 layers in the channel. The residual stress changes from 0.4568 to 1.9234 GPa with number of MoS 2 layers increasing from one to five. At the same time, the band gap of the MoS 2 decreases by 45.4% from 1.727 to 0.943 eV. Our simulations show that when residual stress increases, the Schottky barrier height and the MoS 2 /H–SiO 2 interface barrier height can significantly decrease and the drain-source and direct tunneling currents will inevitably increase. The results in this paper provide a theoretical basis for the fabrication of strained MoS 2 devices. • A novel approach to the number of layers and stress-strain in MoS 2 /SiO 2. • Relationship between layer numbers and stress/strain is revealed. • The effect of layers on tunneling current is explained. • Tunability of characteristics of MoS 2 devices by changing the number of MoS 2 layers. [ABSTRACT FROM AUTHOR]

The catalytic performance of CO oxidation on the TiO 2 -supported gold catalysts would be affected by the O vacancies on a TiO 2 surface. First-principle studies here are focused on how the O vacancy addresses the performance of single atom catalysts on CO oxidation. Three possible configurations of gold adatoms and O vacancies on anatase TiO 2 (001) support are considered as follows: A gold adatom above an O vacancy, a gold adatom or two gold adatoms above an O vacancy dimer. The O vacancy dimer favors the binding of negatively charged gold adatoms on anatase TiO 2 (001) support. However, the dual gold adatoms slightly increase the barrier energy in CO oxidation through the Au-assisted Mars-van Krevelen mechanism. The formation of a stable carbonate on the initial-existing O vacancy reveals that the extra O vacancy deteriorates the catalytical performance of CO oxidation. In final, the high catalytic performances of TiO 2 /Au catalyst are attributed to the synergistic effects between a negatively charged Au adatom and a lower-coordinated Ti3+ ion. • A stable carbonate occurs at the site of extra O vacancy. • O vacancy dimer reduces the catalytical performance of CO oxidation. • Synergistic effects exist between a negatively charged Au atom and a Ti3+ ion. [ABSTRACT FROM AUTHOR]

Medicinal plants provide crucial ecosystem services, especially in developing countries such as China, which harbors diverse endemic medicinal plant species with substantial cultural and economic value. Accordingly, understanding the patterns and drivers of medicinal plant distribution is critical. However, few studies have investigated the patterns and drivers of endemic medicinal plants distribution in China. Here, we linked endemic medicinal plants distribution with possible explanatory variables, i.e., paleoclimate change, contemporary climate, altitudinal range and ethnic minority human population size at the prefecture city level in China. Our results show that endemic medicinal plants are concentrated in southern China, especially in southwestern China. Notably, both endemic medicinal plant species richness and the ratio of endemic medicinal plant species richness are negatively associated with glacial-interglacial anomaly in temperature, and positively associated with contemporary precipitation and altitudinal range. In addition, we found that endemic medicinal plant species richness is positively associated with ethnic minority population sizes as well as its ratio to the overall population size. These findings suggest that the distribution of endemic medicinal plants is determined by multiple drivers. Furthermore, our findings stress that dramatic future climate changes and massive anthropogenic activities in southern China pose great challenges to the conservation of China's endemic medicinal plants., Competing Interests: These authors have no conflict in interest., (© 2022 Kunming Institute of Botany, Chinese Academy of Sciences. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co., Ltd.)