National Institute of Advanced Industrial Science and Technology

About: National Institute of Advanced Industrial Science and Technology is a government organization based out in Tsukuba, Ibaraki, Japan. It is known for research contribution in the topics: Catalysis & Thin film. The organization has 22114 authors who have published 65856 publications receiving 1669827 citations. The organization is also known as: Sangyō Gijutsu Sōgō Kenkyū-sho.

High thermoelectric performance in low-cost SnS 0.91 Se 0.09 crystals.

Abstract: Thermoelectric technology allows conversion between heat and electricity. Many good thermoelectric materials contain rare or toxic elements, so developing low-cost and high-performance thermoelectric materials is warranted. Here, we report the temperature-dependent interplay of three separate electronic bands in hole-doped tin sulfide (SnS) crystals. This behavior leads to synergistic optimization between effective mass (m*) and carrier mobility (μ) and can be boosted through introducing selenium (Se). This enhanced the power factor from ~30 to ~53 microwatts per centimeter per square kelvin (μW cm−1 K−2 at 300 K), while lowering the thermal conductivity after Se alloying. As a result, we obtained a maximum figure of merit ZT (ZTmax) of ~1.6 at 873 K and an average ZT (ZTave) of ~1.25 at 300 to 873 K in SnS0.91Se0.09 crystals. Our strategy for band manipulation offers a different route for optimizing thermoelectric performance. The high-performance SnS crystals represent an important step toward low-cost, Earth-abundant, and environmentally friendly thermoelectrics.

Induction of DNA methylation and gene silencing by short interfering RNAs in human cells

Abstract: Double-stranded RNAs (dsRNAs) induce post-transcriptional gene silencing in several species of animal and plant. In plants, dsRNAs targeted to CpG islands within a promoter can also induce RNA-directed DNA methylation; however, it remains unclear whether gene silencing mediated by DNA methylation can be induced by dsRNAs in mammalian cells. Here, we demonstrate that short interfering RNAs (siRNAs; 21-25-nucleotide RNA molecules) induce DNA methylation and histone H3 methylation in human cells. Synthetic siRNAs targeted to CpG islands of an E-cadherin promoter induced significant DNA methylation and histone H3 lysine 9 methylation in both MCF-7 and normal mammary epithelial cells. As a result, these siRNAs repressed expression of the E-cadherin gene at the transcriptional level. In addition, disrupting the expression of either one of two DNA methyltransferases (DNMT1 or DNMT3B) by specific siRNAs abolished the siRNA-mediated methylation of DNA. Moreover, vector-based siRNAs targeted to the erbB2 (also known as HER2) promoter also induced DNA methylation in MCF-7 cells. Thus, siRNAs targeted to CpG islands within the promoter of a specific gene can induce transcriptional gene silencing by means of DNA-methyltransferase-dependent methylation of DNA in human cells, and might have potential as a new type of gene therapeutic agent.

Prediction of Low-Thermal-Conductivity Compounds with First-Principles Anharmonic Lattice-Dynamics Calculations and Bayesian Optimization

Abstract: Compounds of low lattice thermal conductivity (LTC) are essential for seeking thermoelectric materials with high conversion efficiency. Some strategies have been used to decrease LTC. However, such trials have yielded successes only within a limited exploration space. Here, we report the virtual screening of a library containing 54,779 compounds. Our strategy is to search the library through Bayesian optimization using for the initial data the LTC obtained from first-principles anharmonic lattice-dynamics calculations for a set of 101 compounds. We discovered 221 materials with very low LTC. Two of them even have an electronic band gap <1 eV, which makes them exceptional candidates for thermoelectric applications. In addition to those newly discovered thermoelectric materials, the present strategy is believed to be powerful for many other applications in which the chemistry of materials is required to be optimized.

Carbon Nanotubes and Related Nanomaterials: Critical Advances and Challenges for Synthesis toward Mainstream Commercial Applications

Abstract: Advances in the synthesis and scalable manufacturing of single-walled carbon nanotubes (SWCNTs) remain critical to realizing many important commercial applications. Here we review recent breakthroughs in the synthesis of SWCNTs and highlight key ongoing research areas and challenges. A few key applications that capitalize on the properties of SWCNTs are also reviewed with respect to the recent synthesis breakthroughs and ways in which synthesis science can enable advances in these applications. While the primary focus of this review is on the science framework of SWCNT growth, we draw connections to mechanisms underlying the synthesis of other 1D and 2D materials such as boron nitride nanotubes and graphene.