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ε-Fe2O3 is a rare and metastable iron (III) oxide phase. ε-Fe2O3/SiO2 composites were prepared by combining the reverse-micelle and sol-gel methods. An appropriate amount of Ba2+ was needed in this system to promote the formation of ε-Fe2O3 nanorods in SiO2. The size of nanorods varied with different Ba2+ addition amount and sintering procedure. Then pure ε-Fe2O3 nanorods were obtained after stripping SiO2 by etching due to NaOH aqueous solution. The as-synthesized ε-Fe2O3 nanorods were discussed using X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM). Interestingly, metastable ε-Fe2O3 nanorods showed a promising performance for the response for ethanol, compared with the stable phases of α-Fe2O3 and γ-Fe2O3. It indicates that nanostructure ε-Fe2O3 (including ε-Fe2O3 nanorods) could be a valuable material for the fabrication of advanced sensing devices.

In order to improve the compatibility between SiC particles and aluminum, the SiC/Cu composite powders were prepared by using chemical plating method to coat a Cu layer on the SiC particles surface. The obtained powders were made into preform and then put it into molten aluminium. SiC/Cu-Al composite were produced by using pressureless infiltration method under argon gas. By scanning electron microscopy (SEM), optical microscopy (OM), X-ray diffraction (XRD),the phase structure and microstructure of SiC/Cu composite powders and SiC/Cu-Al composite were analysed. Moreover, the temperature and soaking time on the effect of SiC/Cu-Al composite infiltration depth and effect were studied. The results show that: Cu coating on the SiC particles surface distributed uniformly; SiC/Cu-Al composite prepared at the condition of 800℃ and 2 hours soaking time has a densification microstructure, SiC particles uniformly distributed in the aluminum matrix and there is no Al4C3 brittle phase formation; at 700℃～900℃ infiltration, as the temperature growing, infiltration depth increases at first and then decreases; the microstructure of SiC/Cu-Al composite which infiltrated 2 hours is more compact than that 1 hour; Cu coating effectively improved the wettability between SiC particles and molten aluminum, and inhibited the formation of harmful interfacial reaction.

Despite the prokaryotic origins of chloroplasts, a plant chloroplast tRNA precursor is processed in a homologous in vitrosystem by a pathway distinct from that observed in Escherichia coli, but identical to that utilized for maturation of nuclear pre‐tRNAs. The mature tRNA 5′ terminus is generated by the site‐specific endonucleolytic cleavage of an RNase P (or P‐type) activity. The 3′ end is likewise produced by a single precise endonucleolytic cut at the 3′ terminus of the encoded tRNA domain. This is the first complete structural characterization of an organellar tRNA processing system using a homologous substrate. In contrast to eubacterial RNase P, chloroplast RNase P does not appear to contain an RNA subunit. The chloroplast activity bands with bulk protein at 1.28 g/ml in CsCI density gradients, whereas E.coliRNase P bands as ribonucleoprotein at 1.73 g/ml. Chloroplast RNase P activity survives treatment with micrococcal nuclease (MN) at levels 10‐ to 100‐fold higher than those required to totally inactivate the E.colienzyme. The chloroplast system is sensitive to a suppression of tRNA processing, caused by binding of inactive MN to pre‐tRNA substrate, which is readily overcome by addition of carrier RNA to the assay.

Despite the prokaryotic origins of chloroplasts, a plant chloroplast tRNA precursor is processed in a homologous in vitrosystem by a pathway distinct from that observed in Escherichia coli, but identical to that utilized for maturation of nuclear pre‐tRNAs. The mature tRNA 5′ terminus is generated by the site‐specific endonucleolytic cleavage of an RNase P (or P‐type) activity. The 3′ end is likewise produced by a single precise endonucleolytic cut at the 3′ terminus of the encoded tRNA domain. This is the first complete structural characterization of an organellar tRNA processing system using a homologous substrate. In contrast to eubacterial RNase P, chloroplast RNase P does not appear to contain an RNA subunit. The chloroplast activity bands with bulk protein at 1.28 g/ml in CsCI density gradients, whereas E.coliRNase P bands as ribonucleoprotein at 1.73 g/ml. Chloroplast RNase P activity survives treatment with micrococcal nuclease (MN) at levels 10‐ to 100‐fold higher than those required to totally inactivate the E.colienzyme. The chloroplast system is sensitive to a suppression of tRNA processing, caused by binding of inactive MN to pre‐tRNA substrate, which is readily overcome by addition of carrier RNA to the assay.

Block copolymers with different backbone compositions have been prepared by the condensation of dimethylamino terminated poly(dimethylsiloxane) (PDMS) and hydroquinone terminated poly(phthalazinone ether nitrile) (PPEN) in the presence of chlorobenzene/N-methyl pyrrolidone (NMP) as solvents. The products were characterized by FTIR, 1H NMR and gel permeation chromatography. Differential scanning calorimetry analysis indicated that the block copolymers showed separated microphase.

A series of novel poly(aryl ether nitrile)s containing phthalazinone moiety were synthesized by the nucleophilic displacement reaction of bisphenol-like monomers (I) with 2,6-difluorobenzonitrile. The inherent viscosities ranged from 0.46 to 1.07dLg−1. The glass transition temperatures were in the range of 277–295°C, and the temperatures for 10% weight loss in nitrogen atmosphere were found between 495 and 527°C. The structures of these resultant polymers were confirmed by FT-IR and 1H NMR. Moreover, the properties of poly(aryl ether nitrile)s including solubility and crystallinity were also studied.

Inhibition of an RNA processing reaction after treatment with the Ca2+- dependent micrococcal nuclease (MN) is often used as a criterion for the presence of a required RNA or ribonucleoproteln component in the system. Following MN digestion, the nuclease is inactivated with EGTA and radiolabeled substrate is added to assay for remaining RNA processing activity. We found previously that inhibition of RNA processing by MN need not involve RNA hydrolysis: EGTA-inactivated MN can suppress RNA processing if the assay is performed in the absence of carrier RNA. We now demonstrate both by native gel electrophoresis and by nitrocellulose filter retention that EGTA-inactivated MN forms a complex with free RNA which can be dissociated by addition of synthetic polynucleotldes or heparin. In the absence of Ca2+ , nuclease binds to precursor tRNA with an apparent KD ≃ 1.4 × 10−6 M, comparable to its reported affinity for DNA. In an assay for endonucleolytlc tRNA maturation, inactivated MN bound to radiolabeled pre-tRNA physically blocks the sites of endonuclease cleavage and prevents tRNA processing. We call this phenomenon ‘substrate masking’. Addition of excess carrier RNA competes with pre-tRNA for MN binding and restores normal processing.