Search

The influence of water permeates almost all areas including biochemistry, chemistry, physics and is particularly evident in phenomena occurring at the interfaces of solid surface such as SiC nanocrystals, which are promising nanomaterials and exhibit unique surface chemical properties. In this paper, the quantum confinement effect and stability of 3C-SiC nanocrystals in aqueous solution as well as photoluminescence properties in water suspensions with different pH values are reviewed based on design and analysis of surface structures. On this basis, the significant progress of 3C-SiC nanocrystals in efficiently splitting water into usable hydrogen is summarized and the relative mechanisms are described. In addition, the water-soluble 3C-SiC quantum dots as robust and nontoxic biological probes and labels also are introduced as well as future prospects given.

Exploiting the valley degree of freedom to store and manipulate information provides a novel paradigm for future electronics. A monolayer transition-metal dichalcogenide (TMDC) with a broken inversion symmetry possesses two degenerate yet inequivalent valleys, which offers unique opportunities for valley control through the helicity of light. Lifting the valley degeneracy by Zeeman splitting has been demonstrated recently, which may enable valley control by a magnetic field. However, the realized valley splitting is modest (∼0.2 meV T

Chimeric oligonucleotides with the novel morpholino modification and the phosphoramidate linkers have been synthesized and characterized. These oligonucleotides showed moderate thermal stability with complementary RNA and DNA, and enhanced resistance toward the nuclease (t1/2 > 10 h). The phosphoramidate linker made the synthesis of such oligonucleotides applicable on a DNA synthesizer. Under the acidic condition (pH 3.0), the phosphoramidate linkers were readily cleaved, and such property might be useful for the DNA-sequence determination.

Monolayer two-dimensional transition metal dichalcogenides (TMDCs) such as MoS2 with broken inversion symmetry possesses two degenerate yet inequivalent valleys that can be selectively excited by circularly polarized light. This unique property renders interesting valley physics. The ability to manipulate valley degrees of freedom with light or external field makes them attractive for optoelectronic and spintronic applications. There is great demand for large area monolayer (ML) TMDCs for certain measurements and device applications. Recent reports on large area ML TDMCs focus on chemical vapor deposition growth. In this work, we report a facile approach to grow largescale continuous ML MoS2 nearly free of overgrowth and voids, by sulfurizing evaporated molybdenum trioxide ultrathin films. Photo conductivity scales with device sizes up to 4.5 mm, suggesting excellent film uniformity. The growth mechanism is found to be vaporization, diffusion, sulfurization and lateral growth, all at local micrometer scale. Our approach provides a new pathway for large-area ML TMDC growth and lithography-free device fabrication.

siRNAs modified with morpholino nucleoside analogues were synthesized and their biological properties were examined in details. The gene silence abilities of modified siRNAs were correlated to the positions of the modifications, some of which appeared to be more potent than the native siRNA. The 3'-end modification improved the stability of siRNAs in serum significantly. Furthermore, the dose-response and time-course experiments demonstrated that the siRNAs with 3'-end modification have potent gene silence activity at lower concentration and prolonged action time. These favorable properties make the morpholino modified siRNA a potentially useful tool in therapeutic applications.

Hypoxia-activated pro-oligonucleotides were synthesized through the commercial phosphoramidite method, and could be readily cleaved to form normal oligos with good hypoxia selectivity in vitro under the effect of reductases, as well as in tumor cell extract.