Investigating sorption on iron-oxyhydroxide soil minerals by solid-state NMR spectroscopy: a 6Li MAS NMR study of adsorption and absorption on goethite

High-resolution 2H MAS NMR spectra can be obtained for nanocrystalline particles of goethite (alpha-FeOOH, particle size approximately 4-10 nm) at room temperature, facilitating NMR studies of sorption under environmentally relevant conditions. Li sorption was investigated as a function of pH, the system representing an ideal model system for NMR studies. 6Li resonances with large hyperfine shifts (approximately 145 ppm) were observed above the goethite point of zero charge, providing clear evidence for the presence of Li-O-Fe connectivities, and thus the formation of an inner sphere Li+ complex on the goethite surface. Even larger Li hyperfine shifts (289 ppm) were observed for Li+-exchanged goethite, which contains lithium ions in the tunnels of the goethite structure, confirming the Li assignment of the 145 ppm Li resonance to the surface sites.     

Simultaneous profiling analysis of alkylphenols and amines by gas chromatography and gas chromatography–mass spectrometry

Two-phase O-ethoxycarbonylation was performed to alkylphenols in acidic solution with ethyl chloroformate present in dichloromethane phase fortified with triethylamine with subsequent N-ethoxycarbonylation of amines after adjusting to alkaline pH. The resulting ethoxycarbonyl derivatives were subjected to pentafluoropropionylation, clean-up and concentration for analysis by gas chromatography and gas chromatography–mass spectrometry. The present method was linear (r ≥ 0.9959) in the range of 0.5–10.0 μg ml^−l with good precision (≤9.5%) and accuracy (−8.9 to 9.5%) for 20 phenols and 27 amines examined, allowing simultaneous screening for a total of one alkylphenol and four amines from wine and beer.     

Multifunctionality and crystal dynamics of a highly stable, porous metal-organic framework [Zn4O(NTB)2

A porous metal-organic framework [Zn(4)O(NTB)(2)].3DEF.EtOH (1), in which (3,6)-connected nets are doubly interpenetrated to generate curved three-dimensional channels, has been prepared. Framework 1 exhibits high permanent porosity (Langmuir surface area, 1121 m(2)/g; pore volume, 0.51 cm(3)/cm(3)), high thermal stability (up to 430 degrees C), high hydrogen adsorption capacity (1.9 wt % at 77 K and 1 atm), selective organic guest binding ability (K(f)()( )(): MeOH > pyridine > benzene > dodecane), and guest-dependent blue luminescence (lambda(max) depending on guest identity). Most interestingly, the framework sustains single crystallinity even at 400 degrees C and 10(-)(5) Torr, and the framework components undergo reversible dynamics, mainly rotational motion, in response to removal and rebinding of the guest molecules.     

Isoflavone glycosides from the bark of Amorpha fruticosa

Four known isoflavone glucosides have been isolated from the bark of Amorpha fruticosa, which is a traditional remedy plant, for the first time. They were elucidated as 3′-hydroxy-4′-methoxyisoflavone-7-O-β-D-glucopyranoside (1), 4′,6-dimethoxyisoflavone-7-O-β-D-glucopyranoside (2), 4′-methoxyisoflavone-7-O-β-D-glucopyranoside (3), and 3′,5-dihydroxy-4′-methoxyisoflavone-7-O-β-D-glucopyranoside (4), based on the UV, FT-IR, EIMS, FABMS, HREIMS, and NMR (¹H and ¹³C, DEPT, COSY, NOESY, HMQC, and HMBC) data. Published in Khimiya Prirodnykh Soedinenii, No. 4, pp. 336–338, July–August, 2006.     

Copper–Organic Framework Fabricated with CuS Nanoparticles: Synthesis,Electrical Conductivity,and Electrocatalytic Activities for Oxygen Reduction Reaction

To apply electrically nonconductive metal–organic frameworks (MOFs) in an electrocatalytic oxygen reduction reaction (ORR), we have developed a new method for fabricating various amounts of CuS nanoparticles (nano‐CuS) in/on a 3D Cu–MOF, [Cu₃(BTC)₂?(H₂O)₃] (BTC=1,3,5‐benzenetricarboxylate). As the amount of nano‐CuS increases in the composite, the electrical conductivity increases exponentially by up to circa 10⁹‐fold, while porosity decreases, compared with that of the pristine Cu‐MOF. The composites, nano‐CuS(x wt %)@Cu‐BTC, exhibit significantly higher electrocatalytic ORR activities than Cu‐BTC or nano‐CuS in an alkaline solution. The onset potential, electron transfer number, and kinetic current density increase when the electrical conductivity of the material increases but decrease when the material has a poor porosity, which shows that the two factors should be finely tuned by the amount of nano‐CuS for ORR application. Of these materials, CuS(28 wt %)@Cu‐BTC exhibits the best activity, showing the onset potential of 0.91 V vs. RHE, quasi‐four‐electron transfer pathway, and a kinetic current density of 11.3 mA cm^?2 at 0.55 V vs. RHE.     

Target metabolic profiling analysis of free amino acids in plasma as EOC/TBDMS derivatives by GC-SIM-MS

Metabolic profiling analysis of free amino acids (AAs) in plasma (20 microL) was performed by gas chromatography-mass spectrometry in selected ion monitoring mode after ethoxycarbonyl/tert-butyldimethylsilyl derivatives. Characteristic fragment ions, including [M - 57](+) ions, permitted sensitive and selective detection of most of the AAs in the presence of co-extracted carboxylic acids, including free fatty acids, at much higher levels. The overall method was linear (r > or = 0.9991), reproducible (relative standard deviation = 2.3-8.8%) and accurate (relative error = -7.3-7.7%) with detection limits of 0.01-1.9 ng/mL. A total of 18 AAs, 15 protein AAs and three nonprotein AAs were quantitatively screened in a normal human plasma sample. This selective and simple method using a minimal sample volume was effective for the quantitation of plasma free AAs.     

Simultaneous clinical monitoring of lactic acid, pyruvic acid and ketone bodies in plasma as methoxime/tert-butyldimethylsilyl derivatives by gas chromatography-mass spectrometry in selected ion monitoring mode

Simultaneous determination of lactic acid, pyruvic acid, 3-hydroxybutyric acid and acetoacetic acid for clinical monitoring of lactic acidosis and ketone body formation in human plasma (20 microL) was performed by gas chromatography-mass spectrometry in selected ion monitoring (SIM) mode after generating methoxime/tert-butyldimethylsilyl derivatives. All of the targeted carboxylic acids were detected by characteristic fragment ions, which permitted sensitive and selective identification in the presence of co-extracted free fatty acids and other acidic metabolites at much higher levels. The method was linear (r>or=0.9991), reproducible (% relative standard deviation=1.2-5.8), and accurate (% relative error=-7.2-7.6), with detection limits of 0.05-1.7 ng/mL. This rapid, accurate and selective method using minimal plasma samples (20 microL) is useful in the clinical monitoring of lactic acidosis and ketone body formation in plasma.     

Effect of working gases on thermal plasma waste treatment

An electric arc melter used for waste treatment processing is numerically studied. The effects of different plasma working gases are studied by using a laboratory scale test reactor. A two-dimensional finite difference approximation is used to solve the set of governing equations. The Navier-Stokes equations coupled with the combined Maxwell's equation for the electromagnetic fields is used to obtain the temperature and flow fields in the are melter. It is found that the energy efficiency of the air plasma is lower than that of an argon plasma. However, the melted soil volumes are larger using the air plasma than those using the argon plasma. The overall energy efficiency increases cis the gap between the cathode and the soil surface decreases. More uniform gas temperatures are found for the air plasma than that for the argon plasma. Result obtained from the laboratory-scale are melter is used as an input of the energy absorbed into the soil for the USBM arc melter simulation. Results show a maximum temperature of 2195 K at the center of the heat generation and a molten soil exit temperature of 1600 K.