Non-Cartesian sampling schemes and the acquisition of 2D NMR correlation spectra from single-scan experiments

1994 ◽  
Vol 222 (4) ◽  
pp. 371-377 ◽  
Author(s):  
Lucio Frydman ◽  
Jian Peng
Keyword(s):  
2D Nmr ◽  
Methodology ◽  
2012 ◽  
Vol 8 (2) ◽  
pp. 71-80 ◽  
Author(s):  
Juan Botella ◽  
Manuel Suero

In Reliability Generalization (RG) meta-analyses, the importance of bearing in mind the problems of range restriction or biased sampling and their influence on reliability estimation has often been highlighted. Nevertheless, the presence of heterogeneous variances in the included studies has been diagnosed in a subjective way and has not been taken into account in later analyses. Procedures to detect the presence of a variety of sampling schemes and to manage them in the analyses are proposed. The procedures are further explained with an example, by applying them to 25 estimates of Cronbach’s alpha coefficient in the Hamilton Scale for Depression.


1994 ◽  
Vol 91 ◽  
pp. 697-703 ◽  
Author(s):  
B Gillet ◽  
BT Doan ◽  
C Verre-Sebrie ◽  
O Fedeli ◽  
JC Beloeil ◽  
...  

Author(s):  
Benjamin D. McPheron ◽  
Jeffrey L. Schiano ◽  
Brian F. Thomson ◽  
Kiran K. Shetty ◽  
William W. Brey

2013 ◽  
Vol 12 (10) ◽  
pp. 695-701
Author(s):  
Herve Martial Poumale Poumale ◽  
Alphonsine Nkapwa Guedem ◽  
Louis Pergaud Sandjo ◽  
Bonaventure Tchaleu Ngadjui ◽  
Yoshihito Shiono

A new lupane type triterpene (1), together with betulinic acid (2), friedelin (3), aristolochic acid I (4), alpinumisoflavone (5) and 4’-O-methylepinumisoflavone (6) have been isolated from the leaves of Thecacoris annobonea. The structure of the new compound was elucidated on the basis of 1 and 2D NMR experiments. The isolated compounds were evaluated for their phytotoxicity and antimicrobial activity. 1 exhibited significant antimicrobial activity at 30 μg/ml and compounds 1, 2, 3, 4, 5 and 6 inhibited root growth lettuce at 100 μg/ml. 


2014 ◽  
Vol 22 (2) ◽  
pp. 217-224
Author(s):  
Houlong JIANG ◽  
Shuduan LIU ◽  
Anding XU ◽  
Chao YANG

2019 ◽  
Vol 16 (6) ◽  
pp. 474-477 ◽  
Author(s):  
Pham Van Khang ◽  
Nguyen Thi Hien Lan ◽  
Le Quang Truong ◽  
Mai Thi Minh Chau ◽  
Mai Xuan Truong ◽  
...  

In this report, two new steroidal glycosides were isolated and determined from n-butanol fraction of A.asphodeloides. The structures were confirmed in comparison with the spectral data of known compounds by using different spectroscopic analysis approaches including 1D & 2D-NMR techniques and HRMS. The anti-proliferation screening against cancer cell lines A549 and HeLa indicated that compound 1 exhibited good inhibitory activities with IC50 values of 0.79 and 0.55 µg/mL, respectively.


2020 ◽  
Vol 17 (2) ◽  
pp. 185-196
Author(s):  
Shyamal K. Jash ◽  
Dilip Gorai ◽  
Lalan C. Mandal ◽  
Rajiv Roy

Flavonoids are considered as a significant class of compounds among the natural products, exhibiting a variety of structural skeletons as well as multidirectional biological potentials. In structural elucidations of natural products, Nuclear Magnetic Resonance (NMR) spectroscopy has been playing a vital role; the technique is one of the sharpest tools in the hands of natural products chemists. The present resume deals with hard-core applications of such spectral technique, particularly in structural elucidation of flavonoids; different NMR techniques including 1H-NMR, 13C-NMR, and 2D-NMR [viz. 1H-1H COSY, COLOC, HMBC, HMQC] are described in detail.


2019 ◽  
Vol 19 (11) ◽  
pp. 1399-1404 ◽  
Author(s):  
Yangcheng Liu ◽  
Wei Liu ◽  
Changlan Chen ◽  
Zheng Xiang ◽  
Hongwei Liu

Background and Purpose:: Patrinia villosa Juss is an important Chinese herbal medicine widely used for thousands of years, but few reports on the ingredients of the herb have been presented. In this study, we aim to isolate the bioactive compound from the plant. Material and Methods:: The air-dried leaves of P. villosa (15kg) were extracted three times with 70% EtOH under reflux. The condensed extract was suspended in H2O and partitioned with light petroleum, dichloromethane and n-BuOH. The dichloromethane portion was then subjected to normal-phase silica gel column chromatography, ODS silica gel column chromatography and semi-preparative HPLC to yield compound 1. Cytotoxicities of 1 were assayed on HepG2, A549 and A2780 cell lines. The mechanism of apoptosis and cell cycle on A549 was confirmed subsequently. Results: A new impecylone (Impecylone A) was isolated from the leaves of Patrinia villosa Juss, and its structures were established using 1D, 2D-NMR spectra and HR-ESI-MS. Impecylone A could selectivity inhibit HepG2 and A549 cell lines. The compound could induce apoptosis of A549 and arrest the cell cycle at G2/M phase in a dose-dependent manner. Conclusion: Impecylone A is a novel compound from Patrinia villosa Juss and could be a potential antitumor agent especially in the cell lines of A549.


2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Xichuan Liu ◽  
Taichang Gao ◽  
Yuntao Hu ◽  
Xiaojian Shu

In order to improve the measurement of precipitation microphysical characteristics sensor (PMCS), the sampling process of raindrops by PMCS based on a particle-by-particle Monte-Carlo model was simulated to discuss the effect of different bin sizes on DSD measurement, and the optimum sampling bin sizes for PMCS were proposed based on the simulation results. The simulation results of five sampling schemes of bin sizes in four rain-rate categories show that the raw capture DSD has a significant fluctuation variation influenced by the capture probability, whereas the appropriate sampling bin size and width can reduce the impact of variation of raindrop number on DSD shape. A field measurement of a PMCS, an OTT PARSIVEL disdrometer, and a tipping bucket rain Gauge shows that the rain-rate and rainfall accumulations have good consistencies between PMCS, OTT, and Gauge; the DSD obtained by PMCS and OTT has a good agreement; the probability of N0, μ, and Λ shows that there is a good agreement between the Gamma parameters of PMCS and OTT; the fitted μ-Λ and Z-R relationship measured by PMCS is close to that measured by OTT, which validates the performance of PMCS on rain-rate, rainfall accumulation, and DSD related parameters.


Author(s):  
Gediminas Skvarnavičius ◽  
Zigmantas Toleikis ◽  
Vilma Michailovienė ◽  
Christian Roumestand ◽  
Daumantas Matulis ◽  
...  
Keyword(s):  
2D Nmr ◽  

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