Radical-based destruction of nitramines in water: kinetics and efficiencies of hydroxyl radical and hydrated electron reactions

In support of the potential use of advanced oxidation and reduction process technologies for the removal of carcinogenic nitro-containing compounds in water reaction rate constants for the hydroxyl radical and hydrated electron with a series of low molecular weight nitramines (R(1)R(2)-NNO(2)) have been determined using a combination of electron pulse radiolysis and transient absorption spectroscopy. The hydroxyl radical reaction rate constant was fast, ranging from 0.54-4.35 × 10(9) M(-1) s(-1), and seen to increase with increasing complexity of the nitramine alkyl substituents suggesting that oxidation primarily occurs by hydrogen atom abstraction from the alkyl chains. In contrast, the rate constant for hydrated electron reaction was effectively independent of compound structure, (k(av) = (1.87 ± 0.25) × 10(10) M(-1) s(-1)) indicating that the reduction predominately occurred at the common nitramine moiety. Concomitant steady-state irradiation and product measurements under aerated conditions also showed a radical reaction efficiency dependence on compound structure, with the overall radical-based degradation becoming constant for nitramines containing more than four methylene groups. The quantitative evaluation of these efficiency data suggest that some (～40%) hydrated electron reduction also results in quantitative nitramine destruction, in contrast to previously reported electron paramagnetic measurements on these compounds that proposed that this reduction only produced a transient anion adduct that would transfer its excess electron to regenerate the parent molecule.     

Large-scale profiling of diterpenoid glycosides from Stevia rebaudiana using ultrahigh performance liquid chromatography/tandem mass spectrometry

The plant Stevia rebaudiana accumulates a suite of diterpenoid metabolites that are natural sweeteners finding increased use as sugar substitutes. To guide breeding of stevia plants that accumulate substances with desirable flavor in high yield, rapid and accurate methods are needed to profile these substances in plant populations. This report describes an 8-min ultrahigh performance liquid chromatography-tandem mass spectrometry method for separation and quantification of seven stevia glycosides including steviolbioside; stevioside; rebaudiosides A, B, and C; rubusoside; and dulcoside as well as aglycones steviol and isosteviol. This negative mode electrospray ionization/multiple reaction monitoring method yielded low limits of detection <1 ng/mL for steviol, 6 ng/mL for isosteviol, and <15 ng/mL for all stevia glycosides. Stevioside and Reb A, B, and C were quantified in more than 1,100 extracts from stevia leaves as part of a large-scale profiling exercise. Leaf tissue levels in this population spanned about two orders of magnitude for stevioside (2-125 mg/g dry weight), Reb A (2.5-164 mg/g), Reb B (0.5-50 mg/g), and Reb C (1.5-125 mg/g), but levels of individual metabolites exhibited independent variation. The wide spread of metabolite levels highlights the utility and importance of performing targeted metabolic profiling for large plant populations.     

(Bbpy)(HSO_4)_2无卤素可重复使用 Brnsted 离子液体催化剂用于一锅法多组分合成非对称多氢喹啉衍生物（英文）

1,1'‐Butylenebispyridinium hydrogen sulfate is an efficient, halogen‐free and reusable Brnsted ionic liquid catalyst for the synthesis of ethyl‐4‐aryl/heteryl‐hexahydro‐trimehtyl‐5‐ oxoquino‐line‐3‐carboxylates by the one‐pot condensation of dimedone, aryl/heteryl aldehydes, ethyl aceto‐acetate, and ammonium acetate under solvent‐free conditions. This method has the advantages of high yield, clean reaction, simple methodology, and short reaction time. The ionic liquid can be re‐cycled five times without significant loss of the catalytic activity.     

Corrigendum to: Discussion on Active aeroelastic control of 2-D wing-flap systems operating in an incompressible flowfield and impacted by a blast pulse by Librescu et al., Journal of Sound and Vibration 283 (3–5) (2005) 685–706 [Journal of Sound Vibration 332 (13) (2013) 3351–3358]

This corrigendum supplies a corrected statement of an equation in our discussion paper recently appearing in Journal of Sound and Vibration 332 (13) (2013) 3351–3358. This equation concerns the control input coefficient matrix of the state-space representation of the aeroelastic system. It illustrates the influence of the error in the calculation of aeroelastic impulse, step, and ramp responses, as well as demonstrating the accuracy and legitimacy of the present model in comparison to well-established literature data.