The effects of a crowded environment on DNA-mediated electron transfer were evaluated using a pyrene-modified oligonucleotide containing a hole-trapping nucleobase in poly(ethylene glycol) mixed ...solutions. Rapid decompositions of hole-trapping bases in condensed and noncondensed DNA showed that more efficient electron transfer occurred under crowded conditions than in dilute solutions.
The frontier of lifecycle assessment (LCA) case studies has moved from understanding conventional technologies to analyzing emerging technologies at the research and development (R&D) phase. One new ...challenge in LCA that aims to deal with this phenomenon is the development of methods to estimate the environmental impacts of emerging technologies in the R&D phase while considering manufacturing at scale. This study proposes a simple and feasible method that allows LCA practitioners to consider scaling effects of energy consumption during production in a case study of the super growth method of producing carbon nanotubes. In this case, the greenhouse gas (GHG) impact of producing 1 kg of carbon nanotubes decreases from 47.05 t-CO2eq to 21.33 t-CO2eq by scaling up the process. Although the total GHG impacts at the commercial scale estimated from the lab scale inventory are similar to those estimated from the pilot scale inventory, the share of GHG emissions of materials are different because of a change in substrate and a change from batch processing to continuous processing. Carbon nanotube production by the super growth method is competitive with those made by other processes from the viewpoint of GHG impact and product quality.
•LCA framework considering upscaling of process is developed.•47 t-CO2eq of carbon nanotubes decreases to under 21 t-CO2eq by upscaling.•GHG impact changes by upscaling method of direct or indirect method.•GHG impact and their distribution differ by the phases of technology.
Spermidine, a trivalent organic cation, induced DNA structural changes and suppressed guanine photooxidative decomposition via electron transfer through pyrene-modified DNA. On the other hand, adding ...higher concentrations of spermidine resulted in DNA condensation. The efficiency of guanine decomposition in condensed pyrene-modified DNA was promoted remarkably.
It is known that double-stranded DNA (dsDNA) turns into a liquid crystalline phase by the addition of a high concentration of polymer with salt. SYBR Green I (SG) is a well-known sensitive ...fluorescent stain for dsDNA, and is intercalated in liquid crystalline DNA. Formation of the liquid crystalline dsDNA-SG complex has been confirmed by CD spectral measurements, fluorescence spectral measurements and confocal fluorescence microscopy. SG in dsDNA was also used as a singlet oxygen generator. We conducted photoirradiation experiments using three kinds of 42-mer oligonucleotides with SG. The amount of guanine decomposition by selective irradiation of SG was analyzed using HPLC after digestion of dsDNA in each sample solution. We found that singlet oxygen produced in liquid crystalline DNA promoted guanine damage much more efficiently than in homogeneous solution.
We report the interplay between the carbon nanotube (CNT) structure (wall number and diameter) and assembly structure (packing density) on the electrical conductivity of CNT thin films. By ...controlling the CNT average wall number from 1.0 to 5.5 (and inevitably changing of the diameter from 3.0 to 8.7nm), the electrical conductivity of CNT films showed a unique and unexpected phenomenon, i.e. peaking for films made from an average wall number of ∼2.7 that was ∼3-times higher than that from single-walled CNTs and ∼1.6-times higher than that from 5.5-walled CNTs. By developing a first-order model, the individual contributions of individual CNT structure and assembly structure were estimated, and we found that the peak arose from offsetting factors: increase in the effective CNT electrical conductivity and decrease in the packing density with increased wall number. The synergetic effect between the CNT structure and the assembly structure would provide a scientific framework to deeply understand CNT assemblies.
A wafer‐scale integrated energy device circuit (IEDC) consisting of electrochemically isolated microsupercapacitor cells that could be connected in parallel and in series, as well as in arbitrarily ...arrangements. Such an IEDC possesses the same capacitance, operational voltage, and order relaxation time constant, although it is 1/1000th‐times smaller than an equivalent Al electrolytic capacitor.
We report the highly efficient synthesis of sub-2-nm diameter single-walled carbon nanotube (SWCNT) forests with homogenous and controllable diameter (1.5–2.8 nm), millimeter-scale height, and ...extremely high purity. This control was achieved by combining a previously reported sandwich catalyst (Al/Fe/Al) with an atmospheric synthesis process and the water-assisted thermal chemical vapor deposition method. In this way, a dense array of small and stable catalyst nanoparticles, suitable to support vertical growth, while avoiding gas diffusion limitations, could be prepared from which SWCNT forests could be synthesized efficiently to achieve both high purity and mm-scale height. The mm-tall sub-2-nm diameter SWCNT forests showed good quality (Raman G/D ratio of ∼40) and exceptionally high as-grown purity (outer specific surface area of 1215 m2/g; ideal: 1315 m2/g), which can be directly used without additional post-growth purification process to avoid any potential damage to the CNTs. This result represents a significant advance in synthesizing highly pure, mm-scale length SWCNT forests with sub-2-nm diameters.
Clothes represent a unique textile, as they simultaneously provide robustness against our daily activities and comfort (i.e., softness). For electronic devices to be fully integrated into clothes, ...the devices themselves must be as robust and soft as the clothes themselves. However, to date, no electronic device has ever possessed these properties, because all contain components fabricated from brittle materials, such as metals. Here, we demonstrate robust and soft elastomeric devices where every component possesses elastomeric characteristics with two types of single-walled carbon nanotubes added to provide the necessary electronic properties. Our elastomeric field effect transistors could tolerate every punishment our clothes experience, such as being stretched (elasticity: ∼ 110%), bent, compressed (>4.0 MPa, by a car and heels), impacted (>6.26 kg m/s, by a hammer), and laundered. Our electronic device provides a novel design principle for electronics and wide range applications even in research fields where devices cannot be used.
Millimeter waves (30−300 GHz) are starting to be used in next generation high-speed wireless communications. To avoid electromagnetic interference in this wireless communication, finding a suitable ...electromagnetic wave absorber in the millimeter wave range is an urgent matter. In this work, we prepared a high-performance millimeter wave absorber composed of a series of aluminum-substituted ε-iron oxide, ε-Al x Fe2−x O3, nanomagnets (0 ≤ x ≤ 0.40) with a particle size between 25 and 50 nm. The materials in this series have an orthorhombic crystal structure in the Pna21 space group, which has four nonequivalent Fe sites and Al ion that predominantly occupies the tetrahedral FeO4 site. The field-cooled magnetization curves showed that the T C values were 448, 480, and 500 K for x = 0.40, 0.21, and 0, respectively. The magnetization versus external magnetic field showed that the coercive field H c values at 300 K were 10.2, 14.9, and 22.5 kOe for x = 0.40, 0.21, and 0, respectively. The millimeter wave absorption properties were measured at room temperature by terahertz time domain spectroscopy. The frequencies of the absorption peaks for x = 0.40, 0.30, 0.21, 0.09, 0.06, and 0 were observed at 112, 125, 145, 162, 172, and 182 GHz, respectively. These absorptions are due to the natural resonance achieved by the large magnetic anisotropies in this series. Such frequencies are the highest ones for magnetic materials. Because aluminum is the third most abundant atom, aluminum-substituted ε-iron oxide is very economical, and thus these materials are advantageous for industrial applications.
A continuous and wide range control of the diameter (1.9−3.2 nm) and density (0.03−0.11 g cm−3) of single‐walled carbon nanotube (SWNT) forests is demonstrated by decoupling the catalyst formation ...and SWNT growth processes. Specifically, by managing the catalyst formation temperature and H2 exposure, the redistribution of the Fe catalyst thin film into nanoparticles is controlled while a fixed growth condition preserved the growth yield. The diameter and density are inversely correlated, where low/high density forests would consist of large/small diameter SWNTs, which is proposed as a general rule for the structural control of SWNT forests. The catalyst formation process is modeled by considering the competing processes, Ostwald ripening, and subsurface diffusion, where the dominant mechanism is found to be Ostwald ripening. Specifically, H2 exposure increases catalyst surface energy and decreases diameter, while increased temperature leads to increased diffusion on the surface and an increase in diameter.
A continuous and wide range control of the diameter of single‐walled carbon nanotube (SWNT) forests is demonstrated by decoupling the catalyst formation and SWNT growth processes. The diameter and density are inversely correlated, where low/high density forests would consist of large/small diameter SWNTs, which is proposed as a general rule. The model for the catalyst formation process shows that the dominant mechanism is Ostwald ripening.
