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991.
The known phosphonium chloride [HO(Me)CH]4PCl was prepared at ambient conditions from PH3 and acetaldehyde in aqueous HCl, and characterized by elemental analysis and 1H and 31{1H} NMR spectroscopy. Attempts to obtain the tertiary phosphine [HO(Me)CH]3P via reaction of [HO(Me)CH]4PCl with Na2SO3 or Et3N in aqueous media under Ar revealed that [HO(Me)CH]3P is unstable and equilibrates with the secondary phosphine [HO(Me)CH]2PH and acetaldehyde. A 1:4 reaction of [HO(Me)CH]4PCl with NaHSO3 at room temperature under Ar affords first the oxide [HO(Me)CH]2P(O)H and then the phosphinic acid [HO(Me)CH]2P(O)OH. A 1:1 reaction of [HO(Me)CH]4PCl with Na2S2O3 affords the sulfide [HO(Me)CH]3PS. 31{1H} and 1H NMR data for all the (α-hydroxyethyl)phosphorus species are reported for the first time. 相似文献
992.
Bharathi Avula Babu L. Tekwani Narayan D. Chaurasiya NP Dhammika Nanayakkara Yan‐Hong Wang Shabana I. Khan Vijender R. Adelli Rajnish Sahu Mahmoud A. Elsohly James D. McChesney Ikhlas A. Khan Larry A. Walker 《Journal of mass spectrometry : JMS》2013,48(2):276-285
Therapeutic efficiency and hemolytic toxicity of primaquine (PQ), the only drug available for radical cure of relapsing vivax malaria are believed to be mediated by its metabolites. However, identification of these metabolites has remained a major challenge apparently due to low quantities and their reactive nature. Drug candidates labeled with stable isotopes afford convenient tools for tracking drug‐derived metabolites in complex matrices by liquid chromatography‐tandem mass spectrometry (LC‐MS‐MS) and filtering for masses with twin peaks attributable to the label. This study was undertaken to identify metabolites of PQ from an in vitro incubation of a 1:1 w/w mixture of 13C6‐PQ/PQ with primary human hepatocytes. Acquity ultra‐performance LC (UHPLC) was integrated with QTOF‐MS to combine the efficiency of separation with high sensitivity, selectivity of detection and accurate mass determination. UHPLC retention time, twin mass peaks with difference of 6 (originating from 13C6‐PQ/PQ), and MS‐MS fragmentation pattern were used for phenotyping. Besides carboxy‐PQ (cPQ), formed by oxidative deamination of PQ to an aldehyde and subsequent oxidation, several other metabolites were identified: including PQ alcohol, predictably generated by oxidative deamination of PQ to an aldehyde and subsequent reduction, its acetate and the alcohol's glucuronide conjugate. Trace amounts of quinone‐imine metabolites of PQ and cPQ were also detected which may be generated by hydroxylation of the PQ/cPQ quinoline ring at the 5‐position and subsequent oxidation. These findings shed additional light on the human hepatic metabolism of PQ, and the method can be applied for identification of reactive PQ metabolites generated in vivo in preclinical and clinical studies. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
993.
994.
Yan Li Dr. Kazuki Fukushima Dr. Daniel J. Coady Dr. Amanda C. Engler Dr. Shaoqiong Liu Yuan Huang Dr. John S. Cho Dr. Yi Guo Dr. Lloyd S. Miller Dr. Jeremy P. K. Tan Dr. Pui Lai Rachel Ee Dr. Weimin Fan Prof. Yi Yan Yang Dr. James L. Hedrick 《Angewandte Chemie (International ed. in English)》2013,52(2):674-678
995.
Dr. Jing Xu Dominica H. C. Wong James D. Byrne Kai Chen Dr. Charles Bowerman Prof. Joseph M. DeSimone 《Angewandte Chemie (International ed. in English)》2013,52(26):6580-6589
Particle replication in nonwetting templates (PRINT) is a continuous, roll‐to‐roll, high‐resolution molding technology which allows the design and synthesis of precisely defined micro‐ and nanoparticles. This technology adapts the lithographic techniques from the microelectronics industry and marries these with the roll‐to‐roll processes from the photographic film industry to enable researchers to have unprecedented control over particle size, shape, chemical composition, cargo, modulus, and surface properties. In addition, PRINT is a GMP‐compliant (GMP=good manufacturing practice) platform amenable for particle fabrication on a large scale. Herein, we describe some of our most recent work involving the PRINT technology for application in the biomedical and material sciences. 相似文献
996.
Solvent-modified (toluene) copolymers have been prepared from styrene cross-linked with commercial divinylbenzene, m-divinylbenzene, and p-divinylbenzene at divinyl monomer contents of 16 mole % and 32 mole % at FM = 0.50. The resultant copolymers have been characterized by swelling-ratio determinations and rates of sulfonation at 60 and 80°C. The solvent-modified 16 mole % cross-linked copolymers sulfonated at rates slightly greater than those characterizing the 8 mole % cross-linked copolymers prepared in the absence of diluent. The order of decreasing sulfonation rates for both the conventional 8 mole % cross-linked systems and for the solvent-modified 16 mole % cross-linked copolymers is commercial divinylbenzene/styrene, p-divinylbenzene/styrene, m-divinylbenzene styrene. The 32 mole % cross-linked systems exhibit a different order of decreasing sulfonation rates: commercial divinylbenzene/styrene, m-divinylbenzene/styrene, p-divinylbenzene/styrene. The swelling ratios of the 32 mole % solvent-modified copolymers were comparable to those of the conventional 8 mole % cross-linked systems. 相似文献
997.
Kimberly A. Kaplan Veronica M. Chiu Peter A. Lukus Xing Zhang William F. Siems James O. Schenk Herbert H. Hill Jr 《Analytical and bioanalytical chemistry》2013,405(6):1959-1968
We report results of studies of global and targeted neuronal metabolomes by ambient pressure ion mobility mass spectrometry. The rat frontal cortex, striatum, and thalamus were sampled from control nontreated rats and those treated with acute cocaine or pargyline. Quantitative evaluations were made by standard additions or isotopic dilution. The mass detection limit was ~100 pmol varying with the analyte. Targeted metabolites of dopamine, serotonin, and glucose followed the rank order of distribution expected between the anatomical areas. Data was evaluated by principal component analysis on 764 common metabolites (identified by m/z and reduced mobility). Differences between anatomical areas and treatment groups were observed for 53 % of these metabolites using principal component analysis. Global and targeted metabolic differences were observed between the three anatomical areas with contralateral differences between some areas. Following drug treatments, global and targeted metabolomes were found to shift relative to controls and still maintained anatomical differences. Pargyline reduced 3,4-dihydroxyphenylacetic acid below detection limits, and 5-HIAA varied between anatomical regions. Notable findings were: (1) global metabolomes were different between anatomical areas and were altered by acute cocaine providing a broad but targeted window of discovery for metabolic changes produced by drugs of abuse; (2) quantitative analysis was demonstrated using isotope dilution and standard addition; (3) cocaine changed glucose and biogenic amine metabolism in the anatomical areas tested; and (4) the largest effect of cocaine was on the glycolysis metabolome in the thalamus confirming inferences from previous positron emission tomography studies using 2-deoxyglucose. Figure
Instrumental schematic of an ion mobility mass spectrometer used for measuring changes in neuronal metabolomes of varying anatomical regions. Two-dimensional data is generated for each anatomical area of interest 相似文献
998.
Jeanice B. Thomas James H. Yen Katherine E. Sharpless 《Analytical and bioanalytical chemistry》2013,405(13):4539-4548
The vitamin C concentrations in three food-matrix Standard Reference Materials (SRMs) from the National Institute of Standards and Technology (NIST) have been determined by liquid chromatography (LC) with absorbance detection. These materials (SRM 1549a Whole Milk Powder, SRM 1849a Infant/Adult Nutritional Formula, and SRM 3233 Fortified Breakfast Cereal) have been characterized to support analytical measurements made by food processors that are required to provide information about their products’ vitamin C content on the labels of products distributed in the United States. The SRMs are primarily intended for use in validating analytical methods for the determination of selected vitamins, elements, fatty acids, and other nutrients in these materials and in similar matrixes. They can also be used for quality assurance in the characterization of test samples or in-house control materials, and for establishing measurement traceability. Within-day precision of the LC method used to measure vitamin C in the food-matrix SRMs characterized in this study ranged from 2.7 % to 6.5 %. 相似文献
999.
The impact of Cu leveling additives on electrodeposited Cu topography and subsequent planarization behaviour was studied on both the pattern and wafer scales. The leveling agent significantly reduces as-deposited Cu topography, especially “mounding”. The reduction in topography results in a higher effective Cu removal rate during subsequent Cu planarization, both at the pattern and wafer scales. On the wafer scale, this effect is more evident for lower overburdens as the topography must be eliminated in a shorter total polish time. For Cu electrodeposited from leveler additive-free chemistries, significant pattern-scale topography persists throughout almost the entire planarization process, whereas for Cu deposited using a leveling agent only very wide features (~ > 100 μm) show any significant topography evolution during Cu polish. It is shown that excess electrodeposited Cu topography can lead to poor in-plane Cu wiring leakage performance. 相似文献
1000.
Readily available tricyclo[3.2.2.02,4]non-6-en-8-one is converted into the tricyclo ring system of the aristolane sesquiterpenes via an alkoxide accelerated [3, 3]-sigmatropic rearrangement. 相似文献