Effect of acid treatment on thermal extraction yield in ashless coal production

Coals of different ranks were acid-treated in aqueous methoxyethoxy acetic acid (MEAA), acetic acid (AA), and HCl. The acid-treated coals were extracted with polar N-methyl-2-pyrrolidinone (NMP) and nonpolar 1-methylnaphthalene (1MN) solvents at temperatures from 200 to 360 °C for 10-60 min. The thermal extraction yields with NMP for some acid-treated low-rank coals increased greatly; for example, the extraction yield for Wyodak coal (%C; 75.0%) increased from 58.4% for the raw coal to 82.9% for coal treated in 1.0 M MEAA. Conversely, the extraction yields changed minimally for all the acid-treated coals extracted in 1-MN. The type and concentration of acid affected the extraction yield when NMP was used as the extraction solvent. With increasing MEAA concentration from 0.01 to 0.1 M, the extraction yield for Wyodak coal increased from 66.3 to 81.4%, and subsequently did not change clearly with concentration. Similar changes in the extraction yield with acid concentration were also observed with AA and HCl. The de-ashing ratio for coals acid-treated in MEAA, AA, and HCl also increased greatly with concentration from 0.01 to 0.1 M, which corresponded to the change in the thermal extraction yield in NMP. For the acid-treated coals, high extraction yields were obtained at lower extraction temperatures and shorter extraction times than for the raw coal. The mechanisms for the acid treatment and thermal extraction are discussed.     

Reduction of irreversible capacities of amorphous carbon materials for lithium ion battery anodes by Li2CO3 addition

Amorphous carbon materials for lithium ion battery anodes which contain a small amount of Li₂CO₃ were prepared by three methods. The obtained materials were characterized using X-ray diffraction (XRD) analysis, Raman spectroscopy and CO₂ adsorption experiments. Although the XRD profiles and Raman spectra of these materials were similar to those of carbon materials synthesized with no addition, the amount of CO₂ adsorbed was largely decreased by Li₂CO₃ addition. These results suggest that the micropores in these materials were plugged and/or filled with Li₂ CO₃. Galvanostatic lithium charging and discharging experiments showed that the irreversible capacity of the material can be significantly decreased by Li₂CO₃ addition, which is thought to be due to the plugging of the pore inlets by Li₂CO₃. Moreover, it was also found that the reversible capacities of the materials can be increased by adjusting both the amount of Li₂CO₃ addition and carbonization temperature.     

Synthesis of cyclic poly(methyl methacrylate) by the intramolecular cyclization of α-amino, ω-carboxyl heterodifunctional poly(methyl methacrylate)

Summary α-Amino, ω-carboxyl heterodifunctional poly(methyl methacrylate) was prepared by a living anionic polymerization of methyl methacrylate using N,N'-diphenylethylenediamine monolithium amide and succinic anhydride as an initiator and terminator, respectively. Its intramolecular cyclization was carried out to obtain a well-defined cyclic poly(methyl methacrylate). Received: 27 June 2001/Accepted: 16 July 2001     

Thermodynamic work of adhesion and peel adhesion energy of dimethoxysilyl‐terminated polypropylene oxide/epoxy resin system jointed with polymeric substrates

The characterization of the interfacial surface of a dimethoxysilyl‐terminated polypropylene oxide (DMSi–PPO)/diglycidylether of bisphenol A (DGEBA) system, which has the phase structure of DGEBA particles in a DMSi–PPO matrix, was investigated by using model joints with polymeric substrates. The surface free energy (γ) of the DMSi–PPO/DGEBA system had varied with the γ of each substrate. When the system contacted to low surface free energy materials such as Teflon, polypropylene, and polyethylene, the γ of the system showed about 14.3–31.6 mJ/m²; on the other hand, when the system contacted to high surface free energy substrates such as polyethylene–telephthalate and polyimide, the γ of the system showed 50.4 and 64.6 mJ/m², respectively, because the concentration of the DGEBA as a polar component in the system changed around these interfaces. In the low surface energy substrates used, the actual peel adhesion energy value was in good agreement with the thermodynamic work of adhesion (Wa) determined independently. However, in the high surface energy materials used, the peel adhesion energies were 10³–10⁴ times larger than Wa because the energy was dissipated viscoelastically at the jointed points. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1920–1930, 2001     

Liposome‐Based in Vitro Evolution of Aminoacyl‐tRNA Synthetase for Enhanced Pyrrolysine Derivative Incorporation

Methanosarcina species pyrrolysyl‐tRNA synthetase (PylRS) attaches Pyl to its cognate amber suppressor tRNA. The introduction of two mutations (Y384F and Y306A) into PylRS was previously shown to generate a mutant, designated LysZ‐RS, that was able to attach N‐benzyloxycarbonyl‐L ‐lysine (LysZ) to its cognate tRNA. Despite the potential of LysZ derivatives, further LysZ‐RS engineering has not been performed; consequently, we aimed to generate LysZ‐RS mutants with improved LysZ incorporation activity through in vitro directed evolution. Using a liposome‐based in vitro compartmentalization (IVC) approach, we screened a randomly mutagenized gene library of LysZ‐RS and obtained a mutant that showed increased LysZ incorporation activity both in vitro and in vivo. The ease and high flexibility of liposome‐based IVC should enable the evolution of not only LysZ‐RS that can attach various LysZ derivatives but also of other enzymes involved in protein translation.     

Measurement of High-Temperature Elastic Properties of Ceramics Using a Laser Ultrasonic Method

Young's modulus and Poisson's ratio of SiC ceramics at temperatures >1400°C were obtained using a laser ultrasonics method that included a Fabry-Pérot interferometer (LUFP). At temperatures <1000°C, Young's modulus and Poisson's ratio measured using the LUFP method agreed well with those measured using standard contact methods, such as the resonance method and the ultrasonic pulse method. These results showed that the LUFP method is a powerful tool for measuring high-temperature elastic properties of advanced ceramics in a noncontact manner.     

Heterodimerization of Group I Ribozymes Enabling Exon Recombination through Pairs of Cooperative trans‐Splicing Reactions

Group I (GI) self‐splicing ribozymes are attractive tools for biotechnology and synthetic biology. Several trans‐splicing and related reactions based on GI ribozymes have been developed for the purpose of recombining their target mRNA sequences. By combining trans‐splicing systems with rational modular engineering of GI ribozymes it was possible to achieve more complex editing of target RNA sequences. In this study we have developed a cooperative trans‐splicing system through rational modular engineering with use of dimeric GI ribozymes derived from the Tetrahymena group I intron ribozyme. The resulting pairs of ribozymes exhibited catalytic activity depending on their selective dimerization. Rational modular redesign as performed in this study would facilitate the development of sophisticated regulation of double or multiple trans‐splicing reactions in a cooperative manner.     

Stereoselective partitioning of organic substrates by thermoresponsive polymers in aqueous phases

Partitioning of organic substrates by thermoresponsive polymer having N‐acryloylaminoalcohol moieties in aqueous phase has been studied. Thermoresponsive polymers, such as poly(N‐isopropylacrylamide) (PNIPAAm) and poly(NIPAAm‐co‐N‐acryloyl‐(±)‐alaninol) (poly(NIPAAm‐co‐HIPAAm)), were found to concentrate several organic substrates into the hydrophobic field generated during their phase transition. The amount of the substrates recoverd from the polymer phase mainly depended on the hydrophobicity of the substrates. Aqueous solutions of PNIPAAm (lower critical solution temperature, LCST = 33°C) and poly(NIPAAm‐co‐HIPAAm) (LSCT = 41°C) containing 1‐phenylethanol showed LCSTs at 22°C and 33°C, respectively. The changes of LCSTs indicate that specific interactions such as hydrogen bonding between the side chain functionalities of the polymers and the substrates influence the phase transition behavior. Moreover, new optically active polymers having chiral aminoalcohol moieties have been synthesized by copolymerizations of NIPAAm with N‐acryloylaminoalcohols such as N‐acryloyl‐(S)‐alaninol and N‐acryloyl‐(S)‐prolinol. The (R)/(S) ratio of 1‐phenylethanol recovered from poly(NIPAAm‐co‐N‐acryloyl‐(S)‐alaninol) and poly(NIPAAm‐co‐N‐acryloyl‐(S)‐prolinol) were determined to be 75/25 and 68/32, respectively. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3458–3464, 2013     

miR-29 Represses the Activities of DNA Methyltransferases and DNA Demethylases

Members of the microRNA-29 (miR-29) family directly target the DNA methyltransferases, DNMT3A and DNMT3B. Disturbances in the expression levels of miR-29 have been linked to tumorigenesis and tumor aggressiveness. Members of the miR-29 family are currently thought to repress DNA methylation and suppress tumorigenesis by protecting against de novo methylation. Here, we report that members of the miR-29 family repress the activities of DNA methyltransferases and DNA demethylases, which have opposing roles in control of DNA methylation status. Members of the miR-29 family directly inhibited DNA methyltransferases and two major factors involved in DNA demethylation, namely tet methylcytosine dioxygenase 1 (TET1) and thymine DNA glycosylase (TDG). Overexpression of miR-29 upregulated the global DNA methylation level in some cancer cells and downregulated DNA methylation in other cancer cells, suggesting that miR-29 suppresses tumorigenesis by protecting against changes in the existing DNA methylation status rather than by preventing de novo methylation of DNA.