Templated biological synthesis of polymers of abiological monomers

A general method for the in vivo incorporation of amino acid analogues into artificial proteins is described. The method involves the construction of an artificial gene encoding the sequence of interest (with the corresponding natural amino acid encoded in place of the analogue), transformation of a bacterial host strain that cannot synthesize the natural amino acid, and induction of protein synthesis in a host culture enriched in the analogue. Results are described for the amino acid analogues selenomethionine, p-fluorophenylalanine, trifluoroleucine and 3-thienylalanine.     

Migration behaviour of vacancies and damage structure recovery in a Fe-based Fe-Cr-Mn-Cu-Mo multi-component alloy

ABSTRACT

A Fe-based multi-component alloy, 60Fe-12Cr-10Mn-15Cu-3Mo, which presents higher yield stress than typical stainless steels (such as 304, 316, and 340), was used to investigate the thermal stability of irradiation-induced defects. Neutron irradiation was carried out at approximately 323 and 643?K using up to 1.3 × 10^?3 and 4.5 × 10^?4 dpa (displacements per atom), respectively. While no defects were accumulated at the high temperature of 643?K, single vacancies were formed after irradiation at the low temperature of 323?K to 1.3 × 10^?3 dpa, and the vacancies became mobile at 423?K. As a result, vacancy clusters were formed. However, as the annealing temperature increased the size of vacancy clusters decreased. Coincidence Doppler broadening measurements indicated that Cu precipitates were the sites of vacancy cluster formation, and the recovery of vacancy clusters became prominent while annealing the irradiated sample at temperatures higher than 423?K. Recovery of vacancy clusters at 573?K, which was not a high temperature, was also observed even in the sample that was irradiated using 2.5?MeV Fe ions at room temperature to 0.6 dpa at damage peak.     

Design and Evaluation of Tumor-Specific Dendrimer Epigenetic Therapeutics

Histone deacetylase inhibitors (HDACi) are promising therapeutics for cancer. HDACi alter the epigenetic state of tumors and provide a unique approach to treat cancer. Although studies with HDACi have shown promise in some cancers, variable efficacy and off-target effects have limited their use. To overcome some of the challenges of traditional HDACi, we sought to use a tumor-specific dendrimer scaffold to deliver HDACi directly to cancer cells. Here we report the design and evaluation of tumor-specific dendrimer–HDACi conjugates. The HDACi was conjugated to the dendrimer using an ester linkage through its hydroxamic acid group, inactivating the HDACi until it is released from the dendrimer. Using a cancer cell model, we demonstrate the functionality of the tumor-specific dendrimer–HDACi conjugates. Furthermore, we demonstrate that unlike traditional HDACi, dendrimer–HDACi conjugates do not affect tumor-associated macrophages, a recently recognized mechanism through which drug resistance emerges. We anticipate that this new class of cell-specific epigenetic therapeutics will have tremendous potential in the treatment of cancer.     

Demonstration of diamond field effect transistors by AlN/diamond heterostructure

This is the first report on an AlN/diamond heterojunction field effect transistor (HFET). The AlN epilayer is grown on oxygen‐terminated (111) diamond substrates using metalorganic vapor phase epitaxy at a temperature as high as 1240 °C. The transistor and gate capacitance–voltage characteristics indicate that the HFET behaves as a p‐channel FET with a normally‐on depletion mode. The HFET channel is located at the AlN/diamond interface, and holes are accumulated in diamond close to the interface. The development of the AlN/diamond HFET creates a new possibility for diamond‐based power electronics. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Degradable and chemically recyclable epoxy resins containing acetal linkages: Synthesis,properties, and application for carbon fiber‐reinforced plastics

Four sorts of epoxy resins containing degradable acetal linkages were synthesized by the reaction of bisphenol A (BA) or cresol novolak (CN) resin with vinyl ethers containing a glycidyl group [4‐vinlyoxybutyl glycidyl ether (VBGE) and cyclohexane dimethanol vinyl glycidyl ether (CHDMVG)] and cured with known typical amine‐curing agents. The thermal and mechanical properties of the cured resins were investigated. Among the four cured epoxy resins, the CN‐CHDMVG resin (derived from CN and CHDMVE) exhibited relatively high glass transition temperature (T_g = ca. 110 °C). The treatment of these cured epoxy resins with aqueous HCl in tetrahydrofuran (THF) at room temperature for 12 h generated BA and CN as degradation main products in high yield. Carbon fiber‐reinforced plastics (CFRPs) were prepared by heating the laminated prepreg sheets with BA‐CHDMVG (derived from BA and CHDMVE) and CN‐CHDMVG, in which strands of carbon fibers are impregnated with the epoxy resins containing conventional curing agents and curing accelerators. The obtained CFRPs showed good appearance and underwent smooth breakdown with the aqueous acid treatment in THF at room temperature for 24 h to produce strands of carbon fiber without damaging their surface conditions and tensile strength. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Effects of water content on magnesium deposition from a Grignard reagent-based tetrahydrofuran electrolyte

It is well known that water causes decomposition of Grignard reagents. When these reagents are used, water or moisture should be eliminated. However, it is possible that a very small amount of water, for example, trapped in the walls of the glassware used, can enter the system even in a well-controlled Ar glove box. Therefore, in this work, the effect of very low concentrations of water on Mg deposition from a Grignard reagent-based electrolyte was studied. It was shown that a minute amount of water, although insufficient to cause destruction of the Grignard reagent, affects the overpotential for Mg deposition, resulting in Mg deposits of different morphology. For reproducible and reversible Mg deposition and dissolution, it is desirable that the water content of the electrolyte is kept as low as possible and the electrolyte is left to stand for at least several hours after preparation.     

Dissipative crystallization of poly-d-lysine hydrobromide, poly-l-lysine hydrobromide, and their low-molecular-weight analogs

Drying dissipative structures of aqueous solutions of poly-d-lysine hydrobromide, poly-l-lysine hydrobromide, and their low-molecular-weight analogs were studied on a cover glass, a watch glass, and a Petri glass dish. Size of the broad rings, one of the typical macroscopic patterns, decreased as the solute concentration decreased. Microscopic drying crystal patterns of polylysine hydrobromides and their low-molecular-weight analogs, i.e., d-, l-, and dl-lysine hydrochloride changed as a function of the distance from the film center, which is one of the typical features of dissipative crystallization. Macroscopic and microscopic drying patterns were quite similar to each other irrespective of their stereospecificity. The crystal patterns of the mixtures of poly-d-lysine hydrobromide and poly-l-lysine hydrobromide were also similar to those of the corresponding single-component polymers. The stereospecific effects were not observed in this work.