Contact-engineered reconfigurable two-dimensional Schottky junction field-effect transistor with low leakage currents

Abstract Two-dimensional (2D) materials have been considered promising candidates for future low power-dissipation and reconfigurable integrated circuit applications. However, 2D transistors with intrinsic ambipolar transport polarity are usually affected by large off-state leakage currents and small on/off ratios. Here, we report the realization of a reconfigurable Schottky junction field-effect transistor (SJFET) in an asymmetric van der Waals contact geometry, showing a balanced and switchable n- and p-unipolarity with the I ds on/off ratio kept >106. Meanwhile, the static leakage power consumption was suppressed to 10−5 nW. The SJFET worked as a reversible Schottky rectifier with an ideality factor of ~1.0 and a tuned rectifying ratio from 3 × 106 to 2.5 × 10−6. This empowered the SJFET with a reconfigurable photovoltaic performance in which the sign of the open-circuit voltage and photo-responsivity were substantially switched. This polarity-reversible SJFET paves an alternative way to develop reconfigurable 2D devices for low-power-consumption photovoltaic logic circuits

Characterization of CO and/or NO Adsorbed on Reduced Rh-V/SiO2 Catalyst by Infraed Spectroscopy

In situ infrared spectroscopy has been used to study CO and/or NO adsorbed on reduced Rh/SiO2 and Rh-V/SiO2 catalysts. On Rh/SiO2 catalyst reduced at 573K, CO adsorption results in the formation of linear and bridged CO species as well as gem-dicarbonyl to give adsorption bands at 2060, 1867, 2085 and 2028cm(-1) respectively; NO adsorption bands appeared at 1726 and 1650cm(-1). However, on V/SiO2 catalyst reduced at 573K, no CO bands were observed, and two NO bands appeared at 1907 and 1810cm(-1). Furthermore, the NO bands shifted to 1890 and 1756cm(-1) when the V/SiO2 catalyst was reduced at 773K. Introduction of vanadium to the Rh/SiO2 catalyst showed a slight effect on the intensity of the gem-dicarbonyl shifted upwards by about 10cm(-1). These results indicate that the electron transfer from Rh-0 to vanadium ions was enhanced in Rh-V/SiO2 catalyst. Also promotion of reduction of V oxide by Rh was observed during the pretreatment of Rh-V/SiO2 catalyst as detected by ESR experiment. From the results of CO and NO coadsorption, it was found that the absorbed NO sepcies decreased CO adsorption on Rh, particularly, the linear CO species was completely disappeared. For the effects of NO adsorption on CO adsorption, there are two possibilities: (1) direct replacement of CO with NO; (2) oxidation of Rh-0 sites through NO dissociative adsorption. During the coadsorption, two possible intermediates, i.e., RhCONO and Rh(CO)(2)NO, were suggested for the surface process, which requires further investigation

Study of tissue engineered vascularised oral mucosa-like structures based on ACVM-0.25% HLC-I scaffold in vitro and in vivo

AbstractPurpose To explore the feasibility of constructing tissue-engineered vascularised oral mucosa-like structures with rabbit ACVM-0.25% HLC-I scaffold and human gingival fibroblasts (HGFs), human gingival epithelial cells (HGECs) and vascular endothelial-like cells (VEC-like cells).Method Haematoxylin and Eosin (H&E) staining, immunohistochemical, immunofluorescence, 5-ethynyl-2′-deoxyuridine (EdU) staining and scanning electron microscope (SEM) were performed to detect the growth status of cells on the scaffold complex. After the scaffold complex implanted into nude mice for 28 days, tissues were harvested to observe the cell viability and morphology by the same method as above. Additionally, biomechanical experiments were used to assess the stability of composite scaffold.Results Immunofluorescence and Immunohistochemistry showed positive expression of Vimentin, S100A4 and CK, and the induced VEC-like cells had the ability to form tubule-like structures. In vitro observation results showed that HGFs, HGECs and VEC-like had good compatibility with ACVM-0.25% HLC-I and could be layered and grow in the scaffold. After implanted, the mice had no immune rejection and no obvious scar repair on the body surface. The biomfechanical test results showed that the composite scaffold has strong stability.Conclusion The tissue-engineered vascularised complexes constructed by HGFs, HGECs, VEC-like cells and ACVM-0.25% HLC-I has good biocompatibility and considerable strength

Non-RBM Mutations Impaired SARS-CoV-2 Spike Protein Regulated to the ACE2 Receptor Based on Molecular Dynamic Simulation

<jats:p>The emergence of novel coronavirus mutants is a main factor behind the deterioration of the epidemic situation. Further studies into the pathogenicity of these mutants are thus urgently needed. Binding of the spinous protein receptor binding domain (RBD) of SARS-CoV-2 to the angiotensin-converting enzyme 2 (ACE2) receptor was shown to initiate coronavirus entry into host cells and lead to their infection. The receptor-binding motif (RBM, 438–506) is a region that directly interacts with ACE2 receptor in the RBD and plays a crucial role in determining affinity. To unravel how mutations in the non-RBM regions impact the interaction between RBD and ACE2, we selected three non-RBM mutant systems (N354D, D364Y, and V367F) from the documented clinical cases, and the Q498A mutant system located in the RBM region served as the control. Molecular dynamics simulation was conducted on the mutant systems and the wild-type (WT) system, and verified experiments also performed. Non-RBM mutations have been shown not only to change conformation of the RBM region but also to significantly influence its hydrogen bonding and hydrophobic interactions. In particular, the D364Y and V367F systems showed a higher affinity for ACE2 owing to their electrostatic interactions and polar solvation energy changes. In addition, although the binding free energy at this point increased after the mutation of N354D, the conformation of the random coil (Pro384-Asp389) was looser than that of other systems, and the combined effect weakened the binding free energy between RBD and ACE2. Interestingly, we also found a random coil (Ala475-Gly485). This random coil is very sensitive to mutations, and both types of mutations increase the binding free energy of residues in this region. We found that the binding loop (Tyr495-Tyr505) in the RBD domain strongly binds to Lys353, an important residue of the ACE2 domain previously identified. The binding free energy of the non-RBM mutant group at the binding loop had positive and negative changes, and these changes were more obvious than that of the Q498A system. The results of this study elucidate the effect of non-RBM mutation on ACE2-RBD binding, and provide new insights for SARS-CoV-2 mutation research.</jats:p&gt

Pushing the efficiency of high open-circuit voltage binary organic solar cells by vertical morphology tuning

The tuning of vertical morphology is critical and challenging for organic solar cells (OSCs). In this work, a high open-circuit voltage (VOC ) binary D18-Cl/L8-BO system is attained while maintaining the high short-circuit current (JSC ) and fill factor (FF) by employing 1,4-diiodobenzene (DIB), a volatile solid additive. It is suggested that DIB can act as a linker between donor or/and acceptor molecules, which significantly modifies the active layer morphology. The overall crystalline packing of the donor and acceptor is enhanced, and the vertical domain sizes of phase separation are significantly decreased. All these morphological changes contribute to exciton dissociation, charge transport, and collection. Therefore, the best-performing device exhibits an efficiency of 18.7% with a VOC of 0.922 V, a JSC of 26.6 mA cm-2 , and an FF of 75.6%. As far as it is known, the VOC achieved here is by far the highest among the reported OSCs with efficiencies over 17%. This work demonstrates the high competence of solid additives with two iodine atoms to tune the morphology, particularly in the vertical direction, which can become a promising direction for future optimization of OSCs.Published versionG.C. and X.L. acknowledge the financial support from Research Grants Council (RGC) of Hong Kong (General Research Fund No. 14303519 and NSFC/RGC Joint Research Scheme (Grant No. N_CUHK418/17). Z.C. and H.Z. acknowledge the financial support from the National Key Research and Development Program of China (Program No. 2017YFA0207700). X.Z. thanks NSFC (51761165023)