Group 4 initiators for the stereoselective ROP of rac-β-butyrolactone and its copolymerization with rac-lactide

In this paper we demonstrate the utility of Group 4 metals for the well-controlled and stereoselective (syndiotactic) ring opening polymerization (ROP) of rac-β-butyrolactone (BBL) and their ability to form copolymers.     

Thermal stability of functionalized carbon nanotubes studied by in-situ transmission electron microscopy

The thermal stability of funtionalized carbon nanotubes (CNTs) has been studied experimentally by direct in-situ observations using a heating stage in a transmission electron microscope, from room temperature (RT) to about 1000 °C. It was found that the thermal stability of the functionalized CNTs was significantly reduced during the in-situ heating process. Their average diameter dramatically expanded from RT to about 500 °C, and then tended to be stable until about 1000 °C. The X-ray energy dispersive spectroscopy analysis suggested that the diameter expansion was associated with coalescence of the carbon structure instead of deposition with additional foreign elements during the heating process.     

Selective pressurized liquid extraction of estrogenic compounds in soil and analysis by gas chromatography-mass spectrometry

A selective pressurized liquid extraction (SPLE) method, followed by gas chromatography–mass spectrometry (GC–MS), for the simultaneous extraction and clean-up of estrone (E1), 17β-estradiol (E2), 17α-ethynylestradiol (EE2), estriol (E3) and bisphenol A (BPA) from soil samples is described. The on-line clean-up of soil by SPLE was achieved using different organic matter retainers, including silica, alumina and Florisil, the most effective being silica. Thus, different amounts of silica, in conjunction with different extraction solvents (acetone, ethyl acetate, isohexane and dichloromethane), either alone or in combination, were used to extract the target chemicals from spiked soil samples. It was shown that 3 g silica resulted in satisfactory rates of recovery of target compounds and acetone:dichloromethane (1:3, v/v) was efficient in extracting and eluting estrogenic compounds for SPLE. Variables affecting the SPLE efficiency, including temperature and pressure were studied; the optimum parameters were 60 °C and 1500 psi, respectively. The limits of detection (LODs) of the proposed method were 0.02–0.37 ng g⁻¹ for the different estrogenic chemicals studied. The outputs using the proposed method were linear over the range from 0.1 to 120 ng g⁻¹ for E1, E2, EE2, 0.2–120 ng g⁻¹ for E3, and 0.5–120 ng g⁻¹ for BPA. The optimized method was further verified by performing spiking experiments in natural soil matrices; good rates of recovery and reproducibility were achieved for all selected compounds and the method was successfully applied to soil samples from Northeast Scotland, for the determination of the target compounds.     

The separation of tellurium and selenium by polyurethane foam sorbents

Tellurium and selenium can be sorbed from hydrochloric acid and hydrobromic acid solution by both polyether and polyester-based polyurethane foam. Although some acid is needed, the substitution of sodium chloride or sodium bromide increases the extraction significantly. Tellurium is extracted rapidly with > 99% sorbed in 2 min from 1.0/5.0M and 2.0/4.0M hydrochloric acid/sodium bromide. Selenium can also be sorbed quantitatively but much more slowly so that a separation is possible based on the relative rates of extraction. The capacity of polyether foam is 3% by weight of tellurium.     

High-spin [2 x 2] [Fe(III)2Ni(II)2] heterometallic square grid with an S = 3 ground state

A [2 x 2] heterometallic [Fe(III)2Ni(II)2] ferrimagnetic, square-grid complex has been synthesized by the self-assembly reaction of a mononuclear Fe(III) precursor with Ni(NO3)2. Intramolecular antiferromagnetic exchange through the resulting hydrazone O-bridging framework (M-O-M 133.3-136.4 degrees) leads to an S = 3 ground state. Structural and magnetic properties are discussed.     

Vibrational spectroscopy of N-phenylmaleimide

A combination of infrared, Raman and inelastic neutron scattering (INS) spectroscopies with density functional theory (DFT) calculations is used to provide a complete assignment of the vibrational spectra of N-phenylmaleimide and N-(perdeuterophenyl)maleimide. DFT is shown to give very good results for the frequencies and atomic displacements in the modes. These are used to generate INS spectra which are excellent agreement with the observed. The calculated infrared and Raman spectra are much less reliable, although this may be more of a presentation problem than a real failing.     

HPLC post column derivatization of aromatic amines usingN-methyl-9-chloroacridinium triflate

An HPLC post column chemical derivatization procedure based on the interaction between an acridinium triflate and amines to form highly colored derivatives on-line is described for the determination of aromatic amines. Benzocaine and butesin, local anesthetic agents that contain the aromatic amine group, were used as model compounds. Reversed-phase HPLC conditions were developed for both the separation of analytes and the reaction between analytes and the acridinium triflate in the system. Three-dimensional knitted teflon shape coils and the internal diameter and length of the coils were important parameters in reducing band broadening and background noise.N-Methyl-9-chloroacridinium triflate was shown to be applicable to the determination of primary aromatic amines, selected secondary aromatic amines, hydrazides, and hydrazines. Application of the on-line chemical derivatization procedure to the analysis of pharmaceutical dosage forms containing procainamide (primary aromatic amine), isoniazid (hydrazide), and hydralazine (hydrazine) is also described.     

Imaging the cardiovascular system: seeing is believing.

From the basic light microscope through high-end imaging systems such as multiphoton confocal microscopy and electron microscopes, microscopy has been and will continue to be an essential tool in developing an understanding of cardiovascular development, function, and disease. In this review we briefly touch on a number of studies that illustrate the importance of these forms of microscopy in studying cardiovascular biology. We also briefly review a number of imaging modalities such as computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, and positron emission tomography (PET) that, although they do not fall under the realm of microscopy, are imaging modalities that greatly complement microscopy. Finally we examine the role of proper imaging system calibration and the potential importance of calibration in understanding biological tissues, such as the cardiovascular system, that continually undergo deformation in response to strain.