Synthesis and characterization of some novel organometallic aromatic polyamides

Some novel ferrocene containing aromatic polyamides were prepared by low‐temperature solution phase polycondensation of 1,1′‐ferrocenedicarboxylic acid chloride with some newly synthesized aromatic diamines in tetrahydrofuran, in the presence of triethylamine. The amorphous polymers were derived in good yields, and did not melt at >350 °C. The monomers and the resulting polymers were characterized by their physical properties, elemental analysis, ¹H‐NMR, FTIR spectroscopy, differential scanning calorimetry and thermogravimetric analyses. The polymeric products were insoluble in common solvents tested. However, all were miscible in concentrated H₂SO₄, forming reddish brown solutions at ambient conditions. The glass transition temperatures (T_g) of these polymers were quite high, which is characteristic of aramids. They are stable up to 500 °C, with 10% mass loss observed in the range 400–650 °C. The activation energies of pyrolysis for each of the products were calculated by Horowitz and Metzger's method. Solution viscosities of the polymers were reduced in concentrated sulfuric acid, which is due to their non‐Newtonian behavior. Copyright © 2006 John Wiley & Sons, Ltd.     

Sectional image reconstruction and three-dimensional microscopy of small particles by angular spectrum method

In this letter, we demonstrate sectional image reconstruction and three-dimensional microscopy of small particles. We demonstrate sectional image reconstruction and holographic methods to obtain 2D and 3D images of small particles. A single hologram is sufficient to obtain a section containing only the focused parts of the reconstructed image. One can obtain images of different plane sections of a specimen in addition to its 3D display. The reconstruction of a digital hologram is based on the plane-wave expansion of the diffracted wave fields using Fourier optics (this method is also known as the angular spectrum method). With this method, the object-to-hologram distance can be quite small because the minimum-distance requirement does not apply. Furthermore, numerical reconstruction of transparent objects by this method may be interesting for micro-structure measurement.     

Solid‐state 13C, 15N and 29Si NMR characterization of block copolymers with CO2 capture properties

Natural abundance solid‐state multinuclear (¹³C, ¹⁵N and ²⁹Si) cross‐polarization magic‐angle‐spinning NMR was used to study structures of three block copolymers based on polyamide and dimethylsiloxane and two polyamides, one of which including ferrocene in its structure. Assignment of most of the resonance lines in ¹³C, ¹⁵N and ²⁹Si cross‐polarization magic‐angle‐spinning NMR spectra were suggested. A comparative analysis of ¹³C isotropic chemical shifts of polyamides with and without ferrocene has revealed a systematic shift towards higher δ ‐values (de‐shielding) explained as the incorporation of paramagnetic ferrocene into the polyamide backbone. In addition, the ¹³C NMR resonance lines for ferrocene‐based polyamide were significantly broadened, because of paramagnetic effects from ferrocene incorporated in the structure of this polyamide polymer. Single resonance lines with chemical shifts ranging from 88.1 to 91.5 ppm were observed for ¹⁵N sites in all of studied polyamide samples. ²⁹Si chemical shifts were found to be around ?22.4 ppm in polydimethylsiloxane samples that falls in the range of chemical shifts for alkylsiloxane compounds. The CO₂ capture performance of polyamide‐dimethylsiloxane‐based block copolymers was measured as a function of temperature and pressure. The data revealed that these polymeric materials have potential to uptake CO₂ (up to 9.6 cm³ g^?1) at ambient pressures and in the temperature interval 30–40 °C. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis and characterization of bulk amorphous steels

Bulk amorphous steels (BASs) are a novel class of advanced materials having very attractive physical, thermal and mechanical properties and have applications as structural materials. Two BASs Fe₅₀Cr₁₄Mo₁₄C₁₄B₆M₂ (M = Y and Dy) were designed following the Greer’s confusion principle and cylinders of thickness 3-5 mm were synthesized by Cu mold casting technique. Characterization was carried out by techniques of X-ray diffraction (XRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) with attachment of energy dispersive spectroscopy (EDS). The alloys show high glass-forming ability (GFA) as well as high thermal stability. Hardness and elastic moduli of the present steels were found to be about 3-4 times higher as compared to the conventional steels. Steel containing Dy has superior mechanical and thermal properties as compared to the steel containing Y.     

Isolation and structure determination of a new indene derivative from endophytic fungus Aspergillus flavipes Y-62

As part of the search for naturally derived secondary metabolites, a novel indene derivative, compound 1, together with nine known metabolites (2–10) have been purified from an ethyl acetate extract of the plant-associated fungus Aspergillus flavipes Y-62, isolated from Suaeda glauca (Bunge) Bunge which was collected along Zhoushan coast, Zhejiang province, East China. The structure of the new compound 1 was elucidated by extensive use of spectroscopic techniques like 1D, 2D NMR, and HR-TOF-MS, while the known metabolites were established based on both spectral methods as well as by comparison with the previous literature. Compound 1 exhibited antimicrobial activities against the gram-negative pathogen Pseudomonas aeruginosa and Klebsiella pneumoniae with equal MIC values of 32 µg/ml.     

Location of delamination in laminated composite plates by pulsed laser holography

The location of delamination in composite laminates based on their vibration characteristics is presented in this paper. Composite materials are widely used as structural materials for aerospace engineering, because of its excellent mechanical properties such as light weight, high stiffness and anti-corrosion characteristics. This paper uses pulsed electronic speckle pattern interferometry (Pulsed-ESPI) to perform non-destructive evaluation of carbon fiber reinforced plastic (CFRP) laminate plates containing various sizes of artificial defects located at the centre of the specimen, based on vibration characteristic using double-pulsed Ruby laser with a pulse duration of 30 ns. The pulsed separation can be adjusted in between 2 and 800 μs. The main advantage of this technique over conventional ESPI is the ability to carry out measurements even under harsh environmental conditions. From the results, it seems to be effective for the detection of defects in various kinds of composite materials. In this paper, the basic principles of the technique are described briefly.     

Modeling primary substrate controlled biotransformation and transport of halogenated aliphatics in porous media

In situ biorestoration is a groundwater remediation technique in which the indigenous aquifer bacteria are stimulated by injecting compounds to provide carbon source and energy. Stimulated bacteria may transform the target contaminants such as tetrachloroethylene (PCE) and trichloroethylene (TCE) into intermediate products. In this study, we developed a model to simulate the substrate-limited biotransformation of the halogenated solvents present in anoxic groundwater by sequential reductive dehalogenation under methanogenic conditions. The model consists of conservation of mass equations for the primary substrate, immobile indigenous biomass, organic solvents such as PCE and TCE, and their intermediate products trichloroethylene, dichloroethylene, and vinyl chloride. The utilization of primary substrate and the biotransformation of organic solvents are assumed to follow Monod kinetics. The limiting factor on bacterial growth is assumed to be the primary substrate. The microbial yield coefficient is determined from the stoichiometric equation describing the anaerobic process. The model is solved by using a finite difference technique. Results are presented for three different case studies: continuous injection of primary substrate (acetate), single-pulse injection, and double-pulse injection. The single-pulse or double-pulse injection techniques were found to be more effective than continuous injection of primary substrate. Double-pulse technique reduces the clogging of injection wells caused by excessive microbial growth around boreholes and achieves a more uniform distribution of microbial growth in the subsurface. In all cases target compounds were effectively removed. The results, however, indicate substantial levels of intermediate product accumulation. Numerical results of a simplified model which assumes an abundance of primary substrate and a constant population of biomass, compare favorably with experimental data reported in the literature.