Replication of genetic information with self-encoded replicase in liposomes

In all living systems, the genome is replicated by proteins that are encoded within the genome itself. This universal reaction is essential to allow the system to evolve. Here, we have constructed a simplified system involving encapsulated macromolecules termed a "self-encoding system", in which the genetic information is replicated by self-encoded replicase in liposomes. That is, the universal reaction was reconstituted within a microcompartment bound by a lipid bilayer. The system was assembled by using one template RNA sequence as the information molecule and an in vitro translation system reconstituted from purified translation factors as the machinery for decoding the information. In this system, the catalytic subunit of Qbeta replicase is synthesized from the template RNA that encodes the protein. The replicase then replicates the template RNA that was used for its production. This in-liposome self-encoding system is one of the simplest such systems available; it consists of only 144 gene products, while the information and the function for its replication are encoded on different molecules and are compartmentalized into the microenvironment for evolvability.     

Behavior of Liquefied Sands Under Extremely Large Strain Levels in Cyclic Torsional Shear Tests

In order to study the cyclic behavior of liquefied sands at extremely large strain levels up to double amplitude shear strain of about 100%, a series of undrained cyclic torsional shear tests while keeping the specimen height constant was performed on saturated Toyoura sand under different densities, two kinds of in-situ frozen sandy samples and their reconstituted specimens. Due correction was made for the effect of membrane force on the measured shear stress. After exceeding a certain level of overall shear strain, the specimen deformation became non-uniform, which is called as “strain localization” in the present study. The initiation of such localization was associated with the changes in the cyclic amplitude of deviator stress and the increment of shear strain. In the case of Toyoura sand, the limiting value of shear strain to initiate strain localization was found to increase with decrease in the relative density, and such a trend was consistent with the empirical correlation of soil liquefaction when the relative density is higher than 30%. In the case of in-situ frozen sandy samples, their limiting shear strain values were smaller than those of the reconstituted specimens, suggesting that their soil structures were different from each other under different degrees of natural aging effects.     

A Hierarchically Ordered TiO2 Hemispherical Particle Array with Hexagonal‐Non‐Close‐Packed Tops: Synthesis and Stable Superhydrophilicity Without UV Irradiation

A hierarchical TiO₂ ordered hemispherical particle array with hexagonal‐non‐close‐packed (hncp) tops is prepared by pulsed laser deposition (PLD) using a polystyrene colloidal monolayer as a template. Compared with conventional lithography, the route presented has the advantage of low cost for producing hncp nanostructured arrays. This hierarchical particle array exhibits excellent superhydrophilicity with a water contact angle of 0° without further UV irradiation. The superhydrophilic property originates from oxygen defects or vacancies on the surface of the TiO₂ nanoparticles produced by PLD and the increased roughness of the hierarchical particle arrays. More importantly, this property is very stable for half a year and could be used in self‐cleaning surfaces and microfluidic devices.     

Unsolved issues related to thermal-hydraulics in the suppression chamber during Fukushima Daiichi accident progressions

ABSTRACT

On 11 March 2011, the Great East Japan Earthquake and Tsunami hit the Fukushima Daiichi Nuclear Power Station. The Fukushima Daiichi Units 1–3 lost all DC and AC power supplies, which set in motion a chain of events that led to releases of radioactivity to the environment. Since then, TEPCO has made many efforts to investigate the accident progressions and the status of the reactors and containment vessels. However, there still exist several tens of unsolved issues to be investigated for the fully understanding of the accident. In this paper, we introduce the unsolved issues related to thermal-hydraulics in the suppression chamber during the Fukushima Daiichi accident progressions. Especially, in Units 2 and 3, there are possibilities that thermal stratification inside their suppression chambers played an important role. It is important that these phenomena are addressed following both theoretical and experimental approaches as support to severe accident simulations.     

Electron holography for the study of magnetic nanomaterials

Transmission electron microscopes fitted with field-emission guns (to provide coherent electron waves) can be adapted to record the magnetic fields within and surrounding nanoparticles or metal clusters, for example, the lines of force of a nanoferromagnet encapsulated within a multiwalled carbon nanotube. Whereas most chemists are aware that electron microscopy readily identifies crystallographic symmetries and phases, solves structures, and, in conjunction with electron energy-loss spectroscopy, yields valence states and electronic information of materials, relatively few know that it can also provide important quantitative information, with nanometer-scale spatial resolution, pertaining to such materials' magnetic properties. In this Account, with the aid of representative examples embracing solid-state chemistry, geochemistry, and bio-inorganic phenomena, we illustrate how off-axis electron holography affords deep insight into magnetic phenomena on the nanoscale. Specifically, we describe the unprecedented level of information available regarding the magnetic nature of magnetotactic bacteria, magnetic nanoparticle chains and chiral bracelets, and geochemically relevant phenomena involving exsolution (the un-mixing of two mineral phases, as in the magnetite-ulv?spinel system). It is, for example, possible to reveal vortices and multidomain states that have no net magnetization in minute blocks of magnetite. With the current burgeoning interest and activity in nanoscience and nanotechnology, our Account concludes with examples of some existing enigmas that electron holography, especially when augmented by the related technique of electron tomography, might play an important experimental role in resolving, such as the occurrence of ferromagnetism in nanocrystals of silver within carbon tubes and in clusters of alkali metals incarcerated within zeolites.     

In situ fibrous structure oriented polymer blends composed of poly(lactic acid) and polycaprolactone containing peroxide

A fibrous dispersed phase stuffed with polycaprolactone (PCL) was constructed in a poly(lactic acid) (PLA) matrix during an injection‐molding process. The injection‐molding process showed efficiency in forming dispersions with fibrous shapes, and they could impart the ductile property of PCL to the brittle PLA matrix, with appropriate interfacial adhesion arising from the cocrosslinking structure at the PLA/PCL interface by dicumyl peroxide (DCP). However, the addition of excess DCP caused a split of the dispersions resulting from the compatibility increment and the excess crosslinking reaction at the interface and inside each phase. The addition of a small amount of DCP could adhere the interface without splitting of the dispersions. The observed internal structure in the injection moldings showed a morphology transition that changed gradually from a fine fibrous morphology to a coarse morphology at a deeper position in the injection moldings. The tensile properties of sliced local layers, which were fabricated with a sliding microtome, proved that the fibrous morphology was effective in the improvement of ductility of the blends. An X‐ray analysis showed that the shear flow increased the crystalline orientation and formed a different crystalline structure only in the PCL dispersed phase, but its crystalline structure was not the main factor for ductility improvement. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

High-pressure atom transfer radical polymerization of methyl methacrylate for well-defined ultrahigh molecular-weight polymers

The feasibility of high-pressure atom transfer radical polymerization (ATRP) for synthesizing well-defined polymers of extraordinarily high molecular weights was demonstrated. ATRP of methyl methacrylate (MMA) under pressures up to 500 MPa was investigated at 60 °C. The addition of a small amount of a Cu(II)Cl₂/ligand complex along with the general benefits of high pressure of enhancing propagation and suppressing termination brought about an excellent control of polymerization even with an extremely low concentration of ATRP initiator. For example, there was produced PMMA with a number-average molecular weight M_n of 3.6 × 10⁶ and a polydispersity index of 1.24, which had never been achieved by conventional ATRP.     

Compact ellipsometer employing a static polarimeter module with arrayed polarizer and wave-plate elements

A portable ellipsometer with a compact static polarimeter using an arrayed polarizer, an arrayed wave plate, and a CCD image sensor is developed. A high level of repeatability at a measurement speed of 0.3 s is demonstrated by measurement of SiO(2) films ranging from 2 to 300 nm in thickness deposited on an Si wafer. There is the potential to realize an ultracompact ellipsometer module by integrating the optical source and receiver, suitable for deployment in a variety of manufacturing equipment and measurement instruments.     

Seasonal and spatial trends of suspended-particle associated polycyclic aromatic hydrocarbons in urban Shizuoka, Japan

We characterized the monthly variations of 21 polycyclic aromatic hydrocarbons (PAHs) associated with suspended particles in the city of Shizuoka, Japan, over 12 months during 2001 and 2002. The fraction of fine particles (less than 2.5 microm diameter (PM2.5)) ranged from 40 to 60% of total suspended particles over the 12 months of the study, and their concentrations ranged from 19.3 to 41.7 microg/m(3). Almost all the PAHs were found in the PM2.5 fraction, in which the summed concentration (sigma PAH) of the 21 PAHs ranged from 1.0 to 8.4 ng/m(3). PAH concentrations were elevated in the colder seasons, but the concentrations of the PM2.5 fraction of suspended particles were not. The composition of PAHs associated with PM2.5 changed little during the year of our study, indicating that seasonal sources such as heating have little effect. Factor analysis showed that three factors explain little of the seasonal variations in the sources of PAHs. Contour maps showed high concentrations of indicator PAHs for gasoline and diesel engine sources distributed along major roads and near factories on the outskirts of the city. We concluded that the contribution of vehicle exhausts to particle-associated PAHs is significant not only in the central city, but also in outer areas associated with major ring roads, and suggest that air pollution in outskirts of urban area also is concerned for health risk associated with the exposure.