A novel complex [Ni(H2O)4(TO)2](NO3)2·2H2O (TO = 1,2,4-triazole-5-one) was synthesized and structurally characterized by X-ray crystal diffraction analysis. The decomposition reaction kinetic of the complex was studied using TG-DTG. A multiple heating rate method was utilized to determine the apparent activation energy (Ea) and pre-exponential constant (A) of the former two decomposition stages, and the values are 109.2 kJ mol?1, 1013.80 s?1; 108.0 kJ mol?1, 1023.23 s?1, respectively. The critical temperature of thermal explosion, the entropy of activation (ΔS≠), enthalpy of activation (ΔH≠) and the free energy of activation (ΔG≠) of the initial two decomposition stages of the complex were also calculated. The standard enthalpy of formation of the new complex was determined as being ?1464.55 ± 1.70 kJ mol?1 by a rotating-bomb calorimeter. 相似文献
Infrared multiphoton dissociation (IRMPD) on a linear ion trap mass spectrometer is applied for the sequencing of small interfering
RNA (siRNA). Both single-strand siRNAs and duplex siRNA were characterized by IRMPD, and the results were compared with that
obtained by traditional ion trap-based collision induced dissociation (CID). The single-strand siRNA anions were observed
to dissociate via cleavage of the 5′ P—O bonds yielding c- and y-type product ions as well as undergo neutral base loss. Full
sequence coverage of the siRNA anions was obtained by both IRMPD and CID. While the CID mass spectra were dominated by base
loss ions, accounting for ∼25% to 40% of the product ion current, these ions were eliminated through secondary dissociation
by increasing the irradiation time in the IRMPD mass spectra to produce higher abundances of informative sequence ions. With
longer irradiation times, however, internal ions corresponding to cleavage of two 5′ P—O bonds began to populate the product
ion mass spectra as well as higher abundances of [a − Base] and w-type ions. IRMPD of siRNA cations predominantly produced
c- and y-type ions with minimal contributions of [a − Base] and w-type ions to the product ion current; the presence of only
two complementary series of product ions in the IRMPD mass spectra simplified spectral interpretation. In addition, IRMPD
produced high abundances of protonated nucleobases, [G + H]+, [A + H]+, and [C + H]+, which were not detected in the CID mass spectra due to the low-mass cut-off associated with conventional CID in ion traps.
CID and IRMPD using short irradiation times of duplex siRNA resulted in strand separation, similar to the dissociation trends
observed for duplex DNA. With longer irradiation times, however, the individual single-strands underwent secondary dissociation
to yield informative sequence ions not obtained by CID. 相似文献
The influence of vertex angles on the extraordinary optical transmission (EOT) characteristics of isosceles triangular apertures is numerically investigated with a three-dimensional finite-difference time-domain (FDTD) method. It has been found that the resonant peak characteristics are dependent on the vertex angles of triangular aperture (TA) and the polarized directions of incident light. The resonant peak amplitude is dramatically decreased, when the vertex angle is increased. A blue-shift/red-shift phenomenon is observed in both of the two cases. Detailed studies indicate that the transmission peak characteristics are due to the effects of localized surface plasmon modes excited along the sidewalls and Fabry–Pérot-like resonance. The EOT performance of TA arrays is compared with that of the rectangular aperture arrays. In addition, a bow-tie-shaped aperture (BTA) can be recognized as two overlapped TAs. The EOT properties of BTA with varying bow angles are also studied and analyzed. 相似文献
A method has been developed for confirmation and quantitation of ten sulfonylurea herbicides (nicosufuron, thifensulfuron-methyl,
metsulfuron-methyl, sulfometuron-methyl, chlorsulfuron, ethametsulfuron-methyl, tribenuron, bensulfuron-methyl, pyrazosulfuron-ethyl
and chlorimuron-ethyl) in water samples. Herbicides were extracted from water by off-line solid-phase extraction (SPE). Different
types of absorbents were evaluated: silica-based ODS-C18 and two polymeric sorbents, Cleanert HXN and Oasis HLB. Analyte determination and quantitation was performed by liquid chromatography
with electrospray mass spectrometry (LC-ESI-MS) instrumentation, equipped with ion trap mass filter. Confirmatory analysis was carried out by LC/MS/MS. MS data acquisition
was performed by a single or two-ion extracted ion monitoring program. The ten herbicides were measured in fortified tap water.
Average recoveries of the nine analytes (except for tribenuron) from water samples were in the range of 77–109%, and the RSD
ranged from 0.3 to 14.5%. The limit of detections (LODs) varied from 6 to 34.8 ng/L. 相似文献
Selective and specific dihydrogenation of benzene and other arenes has been observed in a low‐temperature helium plasma. A surface Birch reduction mechanism has been proposed in which benzene molecules adsorbed on the discharge surface capture low‐energy surface‐adsorbed electrons and subsequently undergo protonation (see picture). Gas‐phase oxidation processes accompany the reduction reaction.
Exchange for the better : Mesoporous sodalite and NaA zeolite exchanged with Pd2+ exhibit remarkably high activity and reusability in C? C coupling reactions under aerobic atmosphere. It is proposed that the catalytic reactions are mediated by a molecular Pd0 species generated in situ within the pores (see picture), which is oxidized back to Pd2+ by O2, preventing the formation of catalytically inactive Pd0 agglomerates.
The interaction of phenosafranine (PSF) with a glycosaminoglycan of heparin (Hep) in aqueous solution was characterized by cyclic voltammetry (CV) and linear sweep voltammetry (LSV) in this paper and further used for Hep detection. In pH 1.5 Britton‐Robinson (B‐R) buffer solution PSF had a well‐defined voltammetric reductive peak at ?0.256 V (vs SCE), and the electrochemical response was faded by the addition of Hep. Cyclic voltammetric experiments indicated that the electrochemical behaviors of free PSF didn't change no matter whether Hep was presented in PSF solution or not. Based on the decrease of the peak current, a second order derivative linear sweep voltammetry was used to establish a sensitive electroanalytical method for Hep. The peak current was proportional to the concentration of Hep in the range of 0.7~20.0 mg L?1, demonstrating that this method was suitable for routine Hep detection. Under optimal conditions, the linear regression equation for the Hep determination was ΔIp”(nA) = 46.30 C (mg L?1) + 343.31 (n = 11, γ = 0.991) with a detection limit of 0.08 mg L?1 (3σ). The established method was further successfully applied to heparin sodium injection samples determination. The interaction mechanism was discussed based on the electrostatic attraction of the negatively charged Hep with the positively charged PSF, and the stoichiometry of Hep‐PSF was calculated by the voltammetric method. 相似文献