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RATIONALE Despite various porous materials having been widely adopted as spraying tips for direct sample analysis using electrospray ionization mass spectrometry (ESI-MS), the effect of surface property and porosity of spraying tip materials on their analytical performances is not clear. Investigation of their relationships could provide insight into the proper choice and/or design of spraying tip materials for direct sample analysis. METHODS The effect of spraying tip materials with different polarities, including polyester and polyethylene (hydrophobic) and wood (hydrophilic), on the detection sensitivity for a variety of compounds, and on the ESI onset voltage, were studied using ESI-MS. The porosity of each type of spraying tip was characterized by scanning electron microscopy (SEM). Factors governing the detection sensitivity were determined based on the correlation of the detection sensitivity to the ESI onset voltage, the polarity, and the porosity of the spraying tip materials. RESULTS Hydrophobic tips (i.e., polyester and polyethylene) show better detection sensitivity for polar compounds but not for non-polar compounds, while hydrophilic tips (wooden tips) show the opposite effect. This phenomenon could be due to the difference in interaction between the analytes and the tips, causing the analytes to adsorb on the tip to different extents. In addition, the micro-porous nature of the tips could facilitate solvent diffusion for transporting analytes to the tip and maintain a stable spray for recording MS data. With the proper choice of spraying tip materials, trace amount of analytes at the picomole level can be detected with minimal sample pretreatment. CONCLUSIONS Both the polarity and the porosity of the spraying tip materials could significantly affect detection sensitivity for a wide variety of analytes. With proper choice of spraying tip material, ESI on a porous spraying tip could be a sensitive method for the direct analysis of daily life samples. Copyright © 2013 John Wiley & Sons, Ltd.

Gold nanoparticles (AuNPs) were applied and optimized as matrix for matrix-assisted laser desorption/ionization mass spectrometry analysis of animal tissues, and enabled histological analysis of animal tissues at molecular level by imaging mass spectrometry (IMS). AuNPs were coated on animal tissue in a solvent-free manner via argon ion sputtering. Metabolites, including neurotransmitters, fatty acids and nucleobases, were directly detected from mouse brain tissue. Based on region-specific chemical profiles, fine histological features of mouse brain tissue and heterogeneous regions of tumor tissue were both revealed. Copyright © 2011 John Wiley & Sons, Ltd.

Tissue-spray ionization mass spectrometry is developed for the in situ chemical analysis of raw herbs under ambient conditions. We demonstrated that analyte molecules could be directly sprayed and ionized from solvent-wetted ginseng tissues upon the application of high electrical voltage to the tissue sample. Abundant phytochemicals/ metabolites, including ginsenosides, amino acids and oligosaccharides, could be detected from ginseng tissues when the tissue-spray experiments were conducted in positive ion mode. Thermally labile and easily hydrolyzed malonyl-ginsenosides were also detected in negative ion mode. The tissue-spray ionization method enables the direct detection of analytes from raw herb samples and preserves the sample integrity for subsequent morphological and/ or microscopic examination. In addition, this method is simple and fast for chemical profiling of wild-type and cultivated-type American ginsengs with differentiation.

We assessed the relationship between the hemodynamic changes and shock intensity in transvenous atrial defibrillation for chronic AF. The correlation between the clinical profile and atrial DFT and the factors predicting maintenance of SR after successful defibrillation were also investigated. Atrial defibrillation using entirely transvenous leads has been investigated as an alternative means of managing patients with AF. However, the hemodynamic consequence of this technique and the clinical factors predicting defibrillation efficacy have not been evaluated. Thirty-seven patients with chronic AF (4 weeks to 60 months) underwent transvenous atrial defibrillation. Defibrillation was performed by delivering R wave synchronized, biphasic (3/3 ms) shocks with step-up voltages (20-400 V) between defibrillation catheters in the anterolateral right atrium and the distal coronary sinus. Clinical profile of the patients, the DFT, arterial blood pressure, and RR interval during defibrillation and the 6-month recurrence rate were determined. SR was restored in 33 (89%) of 37 patients and the DFT was 3.7 +/- 1.4 J (317 +/- 58 V). Transvenous atrial defibrillation resulted in a mild reduction in blood pressure (6 +/- 10 mmHg), but substantial prolongation of longest postshock RR intervals (507 +/- 546 ms), which were significantly related to the shock intensity (r = 0.5, P < 0.001). There was no ventricular proarrhythmia. The patients' age, body weight, duration of AF, left atrial diameter, and ejection fraction were not related to the success of defibrillation, not the 6-month maintenance rate of SR (39%). However, the patients' age was related to DFT. Apart from transient reduction in blood pressure and shock related pauses that may require backup pacing, transvenous biatrial defibrillation was a highly effective and well-tolerated technique. The absence of clinical determinant for successful defibrillation suggests that restoring SR by transvenous atrial defibrillation could be attempted in most patients with chronic AF.

A series of C2 symmetric chiral ketones were designed and synthesized for catalytic asymmetric epoxidation of unfunctionalized olefins. Among those ketones screened, (R)-7, (R)-9, and (R)-10 were found to be highly efficient catalysts for epoxidation of trans-stilbenes with enantioselectivities in the range of 84−95%. Convincing evidence was provided for a spiro transition state of dioxirane epoxidation. Through the 18O-labeling experiment, chiral dioxiranes were found to be the intermediates in chiral ketone catalyzed epoxidation reactions.

In our effort to search for C2 symmetric and conformationally rigid chiral ketones as catalysts for asymmetric epoxidation, a series of cyclic ketones 4−10 were prepared from the corresponding diacids. Compared with acyclic ketones for epoxidation of trans-stilbene, those 9-, 10-, and 11-membered-ring cyclic ketones were found to have much higher catalytic activities, which were attributed to steric effects, electronic effects, and ring strains. By using the homogeneous acetonitrile−water solvent system, unfunctionalized olefins with various substitution patterns (with 5 mol % of ketone 9) and strongly electron-deficient olefins (with a 1:1 ketone 9:substrate ratio) were epoxidized with Oxone as terminal oxidant in 75−96% yield at room temperature and neutral pH. In addition, oxidation of alcohols (with 20 mol % of ketone 9) was carried out successfully with good isolated yields of aldehydes or ketones (75−88%).