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Quinine-derived thiourea promoted enantioselective Michael addition reactions of 3-substituted phthalides to maleimides

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Science China Chemistry 2019年第5期62卷 649-652页

作者： Jie Wang Xin Li jin-pei Cheng State Key Laboratory of Elemento-Organic Chemistry Collaborative Innovation Center of Chemical Science and EngineeringCollege of ChemistryNankai University

A highly diastereoselective and enantioselective Michael addition/desymmetrization reaction of maleimides with prochiral 3-substituted phthalides catalyzed by quinine-derived bifunctional thiourea was realized. A broad range of the 3,3′-disubstituted phthalides bearing vicinal quaternary-tertiary stereogenic centers were synthesized in moderate to good yields(up to 96%) with high diastereoselectivities(up to >19:1 dr) and enantioselectivities(up to 96:4 er).

关键词： michael addition 3,3′-disubstituted phthalides vicinal quaternary-tertiary stereogenic centers

FDR Control for Pairwise Comparisons of Normal Means Based on Goodness of Fit Test

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Acta Mathematicae Applicatae Sinica 2016年第3期32卷 701-712页

作者： pei jin Xing-zhong XU Na LI School of Mathematics and Statistics Beijing Institute of Technology School of Economics and Management University of the Chinese Academy of Sciences

This study is undertaken to apply a bootstrap method of controlling the false discovery rate （FDR） when performing pairwise comparisons of normal means. Due to the dependency of test statistics in pairwise comparisons, many conventional multiple testing procedures can＇t be employed directly. Some modified pro- cedures that control FDR with dependent test statistics are too conservative. In the paper, by bootstrap and goodness-of-fit methods, we produce independent p-values for pairwise comparisons. Based on these indepen- dent p-values, plenty of procedures can be used, and two typical FDR controlling procedures are applied here. An example is provided to illustrate the proposed approach. Extensive simulations show the satisfactory FDR control and power performance of our approach. In addition, the proposed approach can be easily extended to more than two normal, or non-normal, balance or unbalance cases.

关键词： multiple testing false discovery rate goodness-of-fit test pairwise comparisons p-value resampling

Early changes to dry eye and ocular surface after smallincision lenticule extraction for myopia

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International Journal of Ophthalmology(English edition) 2016年第4期9卷 575-579页

作者： pei-jin Qiu Ya-Bo Yang Eye Center the Second Affiliated Hospital of Zhejiang University School of Medicine

AIM： To investigate the early changes in dry eye symptoms, tear function and ocular surface following small-incision lenticule extraction（SMILE） for myopia.·METHODS： Ninety-seven consecutive patients（193 eyes）who underwent SMILE for myopia were observed in this longitudinal and retrospective study. Parameters evaluated included： subjective dry eye symptoms（dryness, foreign body sensation and photophobia）, tear film breakup time（TBUT）, Schirmer Ⅰ test without anesthesia（S Ⅰ T）, tear meniscus height（TMH） and corneal fluorescein staining. Each parameter was evaluated before, and subsequently at 1d, 1wk, 1 and3 mo after surgery.·RESULTS： Compared with preoperative data, dryness was noted to be significantly increased at 1wk and 1mo postoperatively（P 〈0.01）. Symptoms of photophobia and foreign body sensation demonstrated significant differences at 1d and 1wk as compared with preoperative scores respectively（P 〈0.01）. These values were decreased at 1 and 3mo post-surgery（P 〉0.05）.Conversely the corneal staining scores were higher than the preoperative data at 1d, 1wk and 1mo（P 〈0.01）, but were close to the preoperative level at 3mo postoperatively. There was a significant decrease in TMH at 1wk and 1mo（P 〈0.01）, but the value was close to the preoperative level at 3mo postoperatively（P =0.16）. The examination outcomes of S Ⅰ T were significantly increased at 1d then reduced at 1wk after surgery（P 〈0.01）. Each value subsequently returned to the baseline value at 1 and 3mo（P 〉0.05）. TBUT was significantly decreased at all postoperative time points（P 〈0.01）.· CONCLUSION： SMILE resulted in mild dry eye symptoms, tear film instability and ocular surface damages; however, these complications can recover in a short period of time.

关键词： dry eye myopia ocular surface small incision lenticule extraction

Understanding how charge-charge interaction affects the stereochemistry of enamine fluorination by chiral primary amine catalysis

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Science China Chemistry 2023年第10期66卷 2828-2835页

作者： Yanfang Han Kai Yang Long Zhang Sanzhong Luo jin-pei Cheng Center of Basic Molecular Science(CBMS) Department of ChemistryTsinghua UniversityBeijing 100084China Haihe Laboratory of Sustainable Chemical Transformations Tianjin 300192China

Electrostatic interaction, especially electrostatic attraction, usually plays critical roles in controlling the reactivity and selectivity in catalytic transformations;however, the like-charge repulsion, which is ubiquitous in physical systems, is rarely applied in reaction control. Herein we disclosed an unexpected like-charge repulsion induced enantio-control mode in primary aminecatalyzed fluorination reactions with 1-fluoro-2,4,6-trimethylpyridinium triflate. The ionic reaction works favorably in both highly polar(methanol) and non-polar(hexane) solvents, a seldom observed phenomenon in asymmetric catalysis. Erying plot analysis showed that an inversion temperature existed in Me OH, which was explained by the solvent-solute cluster model under different temperatures. Density functional theory(DFT) study and energy decomposition analysis(EDA) verified that the likecharge repulsion takes effect in polar solvent methanol, while in nonpolar solvents, the steric repulsion associated with ion-pair was found to be the major effect for the observed enantioselectivity.

关键词： aminocatalysis fluorination like-charge repulsion iso-inversion temperature ion-pair effect

Mrakia psychrophila ***.,a new species isolated from Antarctic soil

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2007年第4期8卷 260-265页

作者： XIN Ming-xiu ZHOU pei-jin College of Life Sciences Beijing Normal University Beijing 100875 China Institute of Microbiology Academia Sinica Beijing 100080 China

The yeast strain （Y18） was isolated from a soil sample collected from Fildes Peninsula, Antarctica. The strain is a psychrophilic yeast with optimum and maximum growth temperatures of 10 ℃ and 18 ℃, respectively. Teliospores were formed after 7 d on malt agar, when the germination of teliospores was observed. Both inositol and D-glucuronate were assimilated. Positive results of the DBB （diazonium blue B） color reaction, urease test, and starch formation were observed. The major CoQ is Qs. All results indicated that Y18 belongs to the genes of Mrakia. The 18S rDNA sequence analyses showed that Y18 is closely related to Mrakiafrigida. DNA-DNA relatedness study, and some biochemistry characteristics indicated that Y18 represents a new species for which Mrakia psychrophila sp. nov. is proposed.

关键词： Mrakiapsychrophila Psychrophilic yeast 18S rDNA sequence Teliospores

Primary-Tertiary Diamine/Brønsted Acid Catalyzed α-Allylation of Carbonyl Compounds with Allylic Alcohols

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Chinese Journal of Chemistry 2014年第8期32卷 673-677页

作者： Lingyun Cui Long Zhang Sanzhong Luo jin-pei Cheng Beijing National Laboratory for Molecular Sciences(BNLMS) CAS Key Laboratory of Molecular Recognition and FunctionInstitute of ChemistryChinese Academy of SciencesBeijing 100190China

A simple and directα-allylic alkylation of unmodified aldehydes with allylic alcohols catalyzed by primary amine/Brønsted acid has been *** N,N-dimethylethylenediamine/TfOH was identified as the optimal catalyst to promote this transformation via an enamine process in high yields(up to 88%)and with good diastereoselectivities(up to 9∶1).

关键词： organocatalysis enamine primary-tertiary diamine α-allylic alkylation

Detection of Saponins and Oligosaccharides in Herbs Using Direct Analysis in Real-time Mass Spectrometry

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Chemical Research in Chinese Universities 2017年第2期33卷 172-178页

作者： HE Yangfang LIU Wenlong SU Rui XIU Yang pei jin School of Pharmaceutial Sciences Jilin University Changchun 130021 P R. China Jilin Ginseng Academy Changchun University of Chinese Medicine Changchun 130117 P. R. China The Second Hospital of Jilin University Changchunl 30041 P. R. China

The use of direct analysis m real-time（DART） mass spectrometry（MS） for direct detection of saponins andoligosaccharides is difficult mainly because of the strong polarity of these molecules, which results in challenges re-garding desorption and ionization of the compounds. Structure derivatization, such as methylation, is essential forimproving the volatility and the proton affinity of saponin and oligosaccharides. In this study, solid-phase methylationof saponins and oligosaccharides was accomplished in a stainless steel methylation column, and the methylatedproducts of astragaloside, salidroside, icariin, ginsenosides（Rbl, Rb2, Rb3, Rd, Re, Rf and Rgl）, maltose, isomaltose,sucrose and maltotriose were analyzed using DART-MS. Fragmentations occurred during ionization and tandem massspectrometry, and most fragments corresponded to the glycosidic bond, cross-ring cleavages, and the neutral loss ofCH3OH ions, but the aglycone cleavage fragment was not detected. Furthermore, the method was successfully used inthe rapid and simultaneous analysis of saponins and oligosaccharides in a ginseng extract; quantitative analysis ofginsenoside Rbl was also carried out, and consistent content results were obtained in DART-MS andhigh-performance liquid chromatography（HPLC）.

关键词： Saponin Oligosaccharide Direct analysis in real-time(DART) Methylation

Analysis and management of intraoperative complications during small-incision lenticule extraction

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International Journal of Ophthalmology(English edition) 2016年第11期9卷 1697-1700页

作者： pei-jin Qiu Ya-Bo Yang Eye Center the Second Affiliated Hospital of Zhejiang University School of Medicine

Dear Editor,Iam ***-jin Qiu,from Eye Center,the Second Affiliated Hospital of Zhejiang University School of Medicine in Hangzhou,Zhejiang Province,China.I write to present five cases of intraoperative complications du...

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A soluble polymer-supported NADH model:Synthesis and application

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Chinese Science Bulletin 2010年第25期55卷 2824-2828页

作者： MEI LianRui ZHU Xiao-Qing CHENG jin-pei Department of Chemistry and the State Key Laboratory of Elemento-Organic Chemistry Nankai University Tianjin 300071 China

A polyethylene glycol (PEG)-supported NADH model as a novel organic reductant was designed and synthesized. The reductions of various α,β-unsaturated ketones by the PEG-supported NADH model were examined,and the results showed that the reductions completely and quickly proceed with no catalyst at ambient temperature. The main advantages of this liquid-like PEG-supported NADH model are easy workup,and an optimal potential for recycling use and solvent-free for use in reactions.

关键词：辅酶模型可溶性聚合物合成应用聚乙二醇有机还原剂 NADH 环境温度