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Acta Geologica Sinica(English Edition) 2016年第S1期90卷 31-33页

作者： david a.d.evans dep't.of Geology & Geophysics Yale University

The iconic image of a giant radiating dyke swarm subsequently fragmented into three pieces via supercontinental breakup was produced by Paul May in1971(see next page).That figure presented a large part of

关键词： and Contrasting Basement Geological Provinces Long-Lived Lips Advancing beyond May 1971 How do We deal with the Possibility of Complicated dyke Geometries

Efficacy of nonsolvent flower pollen extracts in healthy women with urinary incontinence:A randomized,double-blind,placebo-controlled,parallel study

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Current Urology 2024年第3期18卷 203-211页

作者： Marc Moulin Erin d.Lewis david C.Crowley Colleen E.May Malkanthi evans KGK Science Inc. LondonOntarioCanada Graminex L.L.C.SaginawMIUSA

Background Urinary incontinence(UI)is a debilitating and common condition that adversely affects quality of *** and surgical approaches for managing UI symptoms may result in undesirable risks and *** randomized,double-blind,placebo-controlled,parallel study investigated the efficacy of 2 nonsolvent flower pollen extracts on UI in healthy *** and methods One-hundred and fourteen women aged 40–75 years who scored≥5 on the International Consultation on Incontinence Questionnaire-Urinary Incontinence Short Form(ICIQ-SF)were randomized to receive either Graminex®RCT Fem™UI,Graminex®PollenBerry®,or placebo for 24 *** primary outcome was the change in the ICIQ-SF score between the trial and placebo groups after 24 weeks of *** secondary outcomes included changes in the frequency of nocturia(recorded in 3-day void diaries)and 24-hour leakage volume(assessed via pad weight)after 6,12,18,and 24 weeks of supplementation and changes in stress-induced urinary leakage volume(after completion of a provocative maneuver challenge)after 24 weeks of *** All the groups demonstrated improvement in ICIQ-SF scores at week 24(pd the greatest improvement in ICIQ-SF scores(−4.07±3.4),followed by the PollenBerry®group(−3.34±2.87)and placebo group(−2.61±3.52).The RCT Fem™UI group had corresponding improvements in 24-hour leakage volume(−17.68±39.84 g)and frequency of nocturia(−0.52±1.26)(p≤0.05).PollenBerry®supplementation significantly improved stress-induced urinary leakage volume(−7.12±15.64 g)at week *** study products demonstrated safe hematological and chemical *** RCT Fem™UI supplementation resulted in significant and clinically meaningful reductions in UI severity,with corresponding improvements in daily urinary leakage volume and frequency of ***®significantly improved stress-induced urinary leakage volume,suggesting that it may be eff

关键词： Urinary incontinence Pollen extract Healthy women dietary supplement ICIQ-SF Urinary leakage

Enantioselective iridium-catalyzed allylic substitution with a Reformatsky reagent: direct construction of β-stereogenic homoallylic esters

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Science China Chemistry 2024年

作者： debasis Pal Kirana d.Veeranna Yuk Fai Wong P.Andrew evans department of Chemistry Queen's University(Canada) Xiangya School of Pharmaceutical Sciences Central South University

The Reformatsky reagent derived from ethyl bromoacetate circumvents the challenge associated with the direct regio-and enantioselective iridium-catalyzed allylic alkylation with an unstabilized aliphatic ester enolate. Notably, this work represents the first example of using a Reformatsky reagent in a metal-allyl reaction, which permits the direct construction of enantioenriched β-stereogenic homoallylic esters without preactivation of the pronucleophile or post-reaction modification of the product(e.g., thermal decarboxylation of a 1,3-dicarbonyl). Moreover, the process allows the coupling of a broad range of sterically and electronically diverse electrophiles bearing aryl, heteroaryl and alkenyl derivatives, including the significantly more challenging alkyl-substituted allylic carbonates. The versatility of the ester product is exemplified by a series of functional group manipulations and the development of a concise and efficient enantioselective total synthesis of the natural product,(+)-descurainolide A. Finally, mechanistic studies indicate that the zinc enolate behaves as a soft nucleophile that undergoes outer-sphere alkylation.

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Layer-by-layer assembly of long-afterglow self-supporting thin films with dual-stimuli-responsive phosphorescence and antiforgery applications

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Nano Research 2017年第10期10卷 3606-3617页

作者： Rui Gao dongpeng Yan david G. evans Xue duan State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical Technology Beijing 100029 China Beijing Key Laboratory of Energy Conversion and Storage Materials College of Chemistry Beijing Normal University Beijing 100875 China

The assembly of thin films （TFs） having long-lasting luminescence can be expected to play an important role in the development of new-generation smart sensors, anti-counterfeiting materials, and information-encryption systems. However, such films are limited compared with their powder and solution counterparts. In this study, by exploiting the self-organization of phosphors in the two-dimensional （2d） galleries between clay nanosheets, we developed a method for the ordered assembly of long-afterglow TFs by utilizing a hydrogen-bonding layer-by-layer （LBL） process. Compared with the pristine powder, the TFs exhibit high polarization and up-conversion room-temperature phosphorescence （RTP）, as well as enhanced quantum yields and luminescence lifetimes, allowing them to be used as room-temperature phosphorescent sensors for humidity and oxygen. Moreover, modified clay-based hybrids with multicolor RTP can serve as anti-counterfeiting marks and triple-mode 2d barcode displays. We anticipate that the LBL assembly process can be extended to the fabrication of other inorganic--organic room-temperature phosphorescent hybrids with smart luminescent sensor and antiforgery applications.

关键词： layer-by-layer self-supporting thin film two-dimensional (2d) ultrathin nanosheets sensor phosphorescence

Immobilization of Penicillin G Acylase on Calcined Layered double Hydroxides

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Chemical Research in Chinese Universities 2003年第3期19卷 324-329页

作者： evans d.G. Key Laboratory of Science & Technology of Controllable Chemical Reactions

A hydrotalcite-like Mg 2+ /Al 3+ layered double hydroxide(LdH) material was prepared by means of a modified coprecipitation method involving a rapid mixing step followed by a separate aging process. LdH calcined at 500 ℃, denoted as CLdH, was characterized by XRd, IR and BET surface area measurements. CLdH has a poor crystalline MgO-like structure with a high surface area and porosity. CLdH was used as a support for the immobilization of penicillin G acylase(PGA). The effect of varying the immobilization conditions, such as pH, contact time and the ratio of enzyme to support, on the activity of the immobilized enzyme in the hydrolysis of penicillin G has been studied. It was found that the activity of the immobilized enzyme decreased slightly with decreasing pH and reached a maximum after a contact time of 24 h. The activity of the immobilized enzyme increased with increasing the ratio of enzyme to support. It was found that the adsorption of PGA inhibited the expected reaction of CLdH with an aqueous medium to regenerate a LdH phase. Its original activity(36%) after 15 cycles of reuse of the immobilized enzyme was retained, but no further loss in the activity was observed.

关键词： Immobilized enzyme Penicillin G acylase Layered double hydroxide Calcination

Synthesis of layered LiMnO_2 by in situ oxidation-intercalation and a study of the reaction mechanism and electrochemical performance

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Chinese Science Bulletin 2005年第3期50卷 213-216页

作者： d.G.evans Key Laboratory of Science and Technology of Controllable Chemical Reactions Ministry of EducationBeijing University of Chemical Tech- nologyBeijing 100029China

Using Mn(OH)2 as precursor, LiOH as lithiat- ing agent and (NH4)2S2O8 as oxidant, layered o-LiMnO2 was obtained by a novel method——in situ oxidation-intercalation under mild conditions (80℃). The product was characterized by XRd, ICP, TEM and Li-NMR. The results reveal that 7 orthorhombic LiMnO2 with high purity and good crystallin- ity can be obtained by this method. during electrochemical tests, a LiMnO2/Li cell shows an initial reversible capacity of 208 mAh·g?1 and a reversible capacity of 180 mAh·g?1 after 30 cycles at room temperature.

关键词： LiMnO2 氧化反应电化学特性锂离子电池分析方法

Structure, flame retarding and smoke suppressing properties of Zn-Mg-Al-CO3 layered double hydroxides

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Chinese Science Bulletin 2005年第11期50卷 1101-1104页

作者： evans d. G. Key Laboratory for Science and Technology of Controllable Chemical Reactions Ministry of Education Beijing University of Chemical Tech- nology Beijing 100029 China

Zn-Mg-Al-CO3 layered double hydroxides (LdHs) have been synthesized by a new method involving separate nucleation and aging steps. The Zn-Mg-Al-CO3 LdHs were characterized by XRd, FT-IR, ICP and TG-dTA. The limiting oxygen index and smoke density of composites of the LdHs with EVA-28 were determined. Incorporation of Zn2+ in the layers of the LdHs was found promoting mate- rial charring and smoke suppression. The mechanism of flame retardation and smoke suppression is discussed. The results show that Zn-Mg-Al-CO3 LdHs have better flame retarding and smoke suppressing effects than Mg-Al-CO3 LdHs.

关键词：分层双氢氧化物烟尘控制成核现象火焰延迟

Comparative susceptibility and immune responses of Asian and European honey bees to the American foulbrood pathogen, Paenibacillus larvae

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Insect Science 2019年第5期26卷 831-842页

作者： Sasiprapa Krongdang Jay d.evans Yanping Chen Wannapha Mookhploy Panuwan Chantawannakul 1Bee Protection Laboratory Department of BiologyFaculty of ScienceChiang Mai UniversityChiang MaiThailand Interdisciplinary Program in Biotechnology Graduate SchoolChiang Mai UniversityChiang MaiThailand USdA-ARS Bee Research LaboratoryBeltsvilleMarylandUSA Environmental Science Research Center Faculty of ScienceChiang Mai UniversityChiang MaiThailand

American foulbrood (AFB) disease is caused by Paenibacillus larvae. Currently, this pathogen is widespread in the European honey bee— Apis mellifera. However, little is known about infectivity and pathogenicity of P. lan'ae in the Asiatic cavity-nesting honey bees, Apis cerana. Moreover, comparative knowledge of P. larvae infectivity and pathogenicity between both honey bee species is scarce. In this study, we examined susceptibility, larval mortality, survival rate and expression of genes encoding antimicrobial peptides (AMPs) including defensin, apidaecin, abaecin, and hymenoptaecin in A. mellifera and A. cerana when infected with P. larvae. Our results showed similar effects of P. larvae on the survival rate and patterns of AMP gene expression in both honey bee species when bee larvae are infected with spores at the median lethal concentration (LC5 0 ) for A. mellifera. All AMPs of infected bee larvae showed significant upregulation compared with noninfected bee larvae in both honey bee species. However, larvae of A. cerana were more susceptible than A. mellifera when the same larval ages and spore concentration of P. larvae were used. It also appears that A. cerana showed higher levels of AMP expression than A. mellifera. This research provides the first evidence of survival rate, LC50 and immune response profiles of Asian honey bees, A. cerana, when infected by P. larvae in comparison with the European honey bee, A. mellifera.

关键词： Apis cerana Apis mellifera honey bee immune gene Paenibacillus larvae susceptibility

Multi-dimensional, light-controlled switch of fluorescence resonance energy transfer based on orderly assembly of 0d dye@micro-micelles and 2d ultrathin-layered nanosheets

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Nano Research 2016年第12期9卷 3828-3838页

作者： Zhixiong Li Ruizheng Liang Simin Xu Wendi Liu dongpeng Yan Min Wei david G. evans Xue duan State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical Technology Beijing 100029 China

Fluorescence resonance energy transfer （FRET） systems have broad applications in visual detection, intelligent materials, and biological imaging, all of which favor the transmission of light through multiple dimensions and in diverse directions. Herein, we have demonstrated multi-dimensional （0d and 2d） FRET within a multi-layer ultrathin film （UTF） by employing a layer-by-layer （LBL） assembly technique. The anionic block copolymer micelle poly（tert-butyl acrylate- co-ethyl acrylate-co-methacrylic acid）（PTBEM） is chosen as a molecular carrier for the incorporation of bis（8-hydroxyquinolate） zinc （Znq2） and open-ring merocyanine （MC）（denoted as （Znq2/MC）@PTBEM）. Alternatively, electrostatic assembly is performed with cationic layered double hydroxide （LdH） nanosheets （denoted as [（Znq2/MC）@PTBEM/LdH]n）. This [（Znq2/MC）@PTBEM/ LdH]n system offers a multi-dimensional propagation medium and ensures that the FRET donor and acceptor are located within their F6rster radii in each direction. The system demonstrates a FRET process that can be switched via alternating ultraviolet/visible （UV/vis） irradiation, with tunable blue-green/red fluorescence, resulting in a FRET efficiency as high as 81.7%. It is expected that this assembly method, which uses 0d micelles on a 2d layered material, can be extended to other systems for further development of multi-dimensional FRET.

关键词： bis(8-hydroxyquinolate)zinc (Znq2) open-ring merocyanine layered double hydroxide layer-by-layerself-assembly multi-dimensionalfluorescence resonanceenergy transfer

Stem cells and tissue engineering in plastic surgery:an update

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Plastic and Aesthetic Research 2020年第5期7卷 63-72页

作者： Gregory R.d.evans Alan d.Widgerow department of Plastic Surgery University of CaliforniaIrvineOrangeCA 92868USA

Stem cells and tissue engineering have made great strides in plastic *** review of the literature evaluates some current background information and recent advances in our laboratory to bring these areas more into the ... 详细信息

关键词： Stem cells plastic surgery fat