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Development of a fast and precise method for simultaneous quantification of the PLGA monomers lactic and glycolic acid by HPLC

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Journal of Pharmaceutical Analysis 2019年第2期9卷 100-107页

作者： marcel Pourasghar Aljoscha Koenneke Peter Meiers Marc Schneider Department of Pharmacy Biopharmaceutics and Pharmaceutical TechnologySaarland University

Poly(lactide-co-glycolide acid)(PLGA) is an extraordinary well-described polymer and has excellent pharmaceutical properties like high biocompatibility and good biodegradability. Hence, it is one of the most used materials for drug delivery and biomedical systems, also being present in several US Food and Drug Administration-approved carrier systems and therapeutic devices. For both applications, the quantification of the polymer is inalienable. During the development of a production process, parameters like yield or loading efficacy are essential to be determined. Although PLGA is a well-defined biomaterial,it still lacks a sensitive and convenient quantification approach for PLGA-based systems. Thus, we present a novel method for the fast and precise quantification of PLGA by RP-HPLC. The polymer is hydrolyzed into its monomers, glycolic acid and lactic acid. Afterwards, the monomers are derivatized with the absorption-enhancing molecule 2,4′-dibromoacetophenone. Furthermore, the wavelength of the derivatized monomers is shifted to higher wavelengths, where the used solvents show a lower absorption,increasing the sensitivity and detectability. The developed method has a detection limit of 0.1 mg/mL,enabling the quantification of low amounts of PLGA. By quantifying both monomers separately, information about the PLGA monomer ratio can be also directly obtained, being relevant for degradation behavior. Compared to existing approaches, like gravimetric or nuclear magnetic resonance measurements, which are tedious or expensive, the developed method is fast, ideal for routine screening, and it is selective since no stabilizer or excipient is interfering. Due to the high sensitivity and rapidity of the method, it is suitable for both laboratory and industrial uses.

关键词： Poly(lactide-co-glycolide acid)(PLGA) Alkaline hydrolysis Quantification Drug delivery system RP-HPLC

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狐狸界的“妲己” 赤狐近亲相残究竟为什么？

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环球人文地理 2024年第5期 74-81页

作者：鲨鲨张扬的小强滕洪亮 M.Leonard Photo marcel Rudolph-Gajda Kcapaldo mihiro＿wildlife Zyabich vladk213

因美丽而招致杀身之祸，为生存而近亲相残。狐狸界的妲己——赤狐，到底是祥瑞，还是祸水？从古至今，民间流传的神话传说、志怪传记都少不了狐狸们的身影。早在远古时期，华夏领袖大禹的妻子涂山九尾狐还是正面形象，可随后一个全然相...

因美丽而招致杀身之祸，为生存而近亲相残。狐狸界的妲己——赤狐，到底是祥瑞，还是祸水？从古至今，民间流传的神话传说、志怪传记都少不了狐狸们的身影。早在远古时期，华夏领袖大禹的妻子涂山九尾狐还是正面形象，可随后一个全然相反的狐狸形象诞生——妲己，她的知名度远远超过涂山氏，并在一定程度上定义了狐狸的妖媚概念。

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An integrated suspended sediment transport monitoring and analysis concept

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International Journal of Sediment Research 2014年第2期29卷 135-148页

作者： Marlene HAIMANN marcel LIEDERMANN Petra LALK Helmut HABERSACK Christian Doppler Laboratory for Advanced Methods in River Monitoring Modelling and EngineeringInstitute of Water ManagementHydrology and Hydraulic Engineering Department of WaterAtmosphere and EnvironmentBOKU-University of Natural Resources and Life SciencesVienna

A new integrated suspended sediment monitoring strategy applying direct and indirect technologies is *** sensors continuously record the turbidity at one point in the channel cross section close to the river bank and are calibrated by water samples taken close to the *** measurements are performed to establish the distribution of suspended sediment in a cross section(bottle samples combined with acoustic devices).Using correction factors(probe and cross-sectional factor) these monitoring methods are combined and it is,thus,possible to fully document the temporal and spatial variability of the suspended sediment transport and to estimate the suspended sediment load for certain time *** monitoring strategy was implemented at various measurement sites in Austria as well as at the Hainburg Road Bridge site on the Danube *** has already been successfully applied for three years at this measurement site and suspended sediment loads during high discharges up to a 15 year flood event have been *** evaluate the new monitoring methods the results were compared with load estimation methods found in the literature including averaging and ratio estimators as well as rating *** results prove that with the new methodology,the temporal variability of the suspended sediment transport can be detected more accurately compared with the other *** also demonstrate that the additional consideration of the spatial distribution of the suspended sediment concentration in the cross section is crucial as the mean concentration in the cross section can significantly exceed the concentration near the banks,especially at large rivers like the Danube River.

关键词： Suspended sediment Integrated suspended sediment monitoring programme Turbidity sensor Acoustic devices Load estimates

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Jasmonates differentially affect interconnected signal-transduction pathways of Pieris rapae-induced defenses in Arabidopsis thaliana

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Insect Science 2011年第3期18卷 249-258页

作者： Tjeerd A.L. Snoeren Colette Broekgaarden marcel Dicke Laboratory of Entomology Wageningen UniversityWageningen University and Research Centre 6708PB Wageningen the Netherlands Plant Research International Wageningen University and Research Centre 6708PB Wageningen the Netherlands

The jasmonic acid （JA） pathway is the main signal-transduction pathway induced by insect folivory. Mutant plants affected in the jasmonate pathway （18：0 and/or 16：0-oxylipin routes） were studied to assess the effects of JA and its oxylipin intermediates 12-oxophytodienoic acid （OPDA） and dinor-OPDA （dnOPDA） on interconnected signal- transduction pathways that underlie induced defenses in Arabidopsis. Our data show that the oxylipin jasmonates dnOPDA, OPDA and JA have different roles in defense signaling induced after feeding by the chewing-biting caterpillar Pieris rapae. Jasmonic acid, and not OPDA or dnOPDA, is the major signaling compound required for the induction of the defense-related genes LOX2 （Lipo：~vgenase 2）, OPR3 （12-Oxophytodienoate reductase 3）, ACX1 （Acyl-CoA oxidase 1） and PAL1 （Phenvlalanine ammonia-lyase 1）. Monitoring PAL1 transcript levels clearly showed that accumulation of JA upon P rapae feeding results in the induction of the salicylic acid pathway. Furthermore, JA is the major signaling compound required for the P rapae-induced expression of the defense-related gene HPL1 （Hydroperoxide lyase 1）. The jasmonate dnOPDA influences the induction of the HPk- branch as well, yet its effect is antagonistic to the effect of JA. Our data show that these jasmonates may be used to fine-tune Arabidopsis＇ herbivore-induced responses in terms of the HPL-branch from the oxylipin pathway.

关键词： gene transcript level herbivory Lepidoptera mutants oxylipin qRT-PCR

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Clinical Presentation, Therapeutic Aspects and Results of Urogental Prolapse in Yaounde

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Open Journal of Urology 2024年第2期14卷 83-94页

作者： Junior Barthelemy Mekeme Mekeme Pierre Joseph Fouda Marie Josiane Ntsama Essomba Jean Cedric Fouda Marie Salome Eko’o Neme marcel Junior Yon Mekeme Achille Y. Kpanou Bright Che Awondo Philip Fernandez Owon’Abessolo marcella Biyouma Achille Aurele Mbassi Robinson Mbu Robinson Fru Angwafo III Department of Urology and Andrology Yaounde Central Hospital Yaounde Cameroon Faculty of Medicine and Biomedical Sciences University of Yaounde I Yaounde Cameroon Department of Surgery Yaounde University Teaching Hospital Yaounde Cameroon Faculty of Medicine and Pharmaceutical Sciences Douala Douala Cameroon Department of Urology and Andrology Laquintini Hospital Douala Douala Cameroon Department of Obstetrics and Gynaecology Yaounde Obstetrics Gynaecology and Pediatrics Hospital Yaounde Cameroon

Introduction: Urogenital prolapse is the descent of one or more elements of the abdominal-pelvic contents into the vaginal cavity. The anterior, middle and posterior anatomical compartments may be involved giving rise to several types of genital prolapse. However, there are various therapeutic modalities ranging from observational procedures to surgery. In Yaounde, urogenital prolapse appears to be a rare clinical entity, and its treatment has not been clearly stated. There is limited data about this subject in our context. Our aim was to study the clinical and therapeutic aspects of urogenital prolapse in Yaounde. Methods: We conducted a descriptive cross-sectional study with retrospective data collection at the Yaounde Gynaecological Obstetric and Pediatric Hospital (YGOPH) and the Yaounde Central Hospital (YCH) over a period of 05 months (from February 2022 to June 2022). All women aged ≥30 years and all women with documented urogenital prolapse admitted to the maternity and urology departments of these two health facilities were included. Data were collected using a structured questionnaire. Data was analyzed using IBM SPSS (statistical package for social sciences) software version 23.0 and the data were reported as mean, standard deviation, frequencies and percentages. Results: A total of 50 patients were recruited;the mean age was 45.8 ± 17 years. The age range was from 21 to 72 years. Majority of the patients were aged more than 55 years (32%). Most of the patients attended primary education (48%). Forty percent of the patients were housewives. The majority of the patients were from West Cameroon (26%). The most common reason for consultation was pelvic heaviness (54%). The most prevalent clinical sign was cystocele (56%), followed by hysterocele (54%). According to the Baden Walker classification, one-third of the patients were classified as first degree (36%). More than half (58%) of patients had the condition located at the first stage. Surgery was perform

关键词： Urogenital Prolapse Cystocele Hysterocele Clinical Surgery

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Materials databases for the computational materials scientist

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International Journal of Minerals,Metallurgy and Materials 2011年第3期18卷 303-308页

作者： marcel H.F. Sluiter Darko Simonovic Emre S. Tasci Materials Science and Engineering 3ME Delft University of Technology Materials innovation institute M2i Física de la Materia Condensada Universidad del Pais Vasco

Until recently, many computational materials scientists have shown little interest in materials databases. This is now changing be-cause the amount of computational data is rapidly increasing and the potential for data mining provides unique opportunities for discovery and optimization. Here, a few examples of such opportunities are discussed relating to structural analysis and classification, discovery of correlations between materials properties, and discovery of unsuspected compounds.

关键词： database systems materials data mining ab initio prediction structural analysis

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Philosophy and Science Dialogue： Free Will

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Frontiers of Philosophy in China 2018年第3期13卷 361-376页

作者： marcel Brass Derk Pereboom Department of Experimental Psychology Ghent University 9000 Gent Belgium Sage School of Philosophy Comell University Ithaca NY 14850 USA

In this dialogue Derk Pereboom and marcel Brass discuss the free will problem from the perspective of philosophy and cognitive neuroscience. First, they give their opinion on how the two disciplines contribute to the free will problem. While Pereboom is optimistic regarding the contribution of science, Brass is more pessimistic and questions the usefulness of an empirical approach to the question whether free will exists or not. Then they outline their position on the free will problem. The idea of a transcendental agent is discussed in more detail. Furthermore, it is discussed whether free will scepticism is a politically, socially, psychologically viable position. Pereboom argues that promoting the idea of free will scepticism can have a positive impact on retributive emotions and the political practice regarding retributive punishment. Brass argues that retributive emotions are deeply rooted in evolution and therefore difficult to change via high-level beliefs about free will. Finally, the future of the free will debate is discussed. Both agree that the dialogue between philosophy and psychology should be intensified. Philosophy can benefit from taking empirical research more seriously. Psychology and neuroscience can benefit from philosophy by appreciating the sophistication and conceptual clarity of the philosophical debate. Both have to find a common language and define common problems that can be tackled from both perspectives.

关键词： free will neuroscience moral responsibility retribution reactive attitudes skepticism

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Ethernet based time synchronization for Raspberry Pi network improving network model verification for distributed active turbulent flow control

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Control Theory and Technology 2015年第2期13卷 204-210页

作者： marcel DUECK Mario SCHLOESSER Stefan van WAASEN Michael SCHIEK Central Institute of Engineering Electronics and Analytics ZEA-2: Electronic SystemsForschungszentrum Juelich Gmb H ZEA-2 Wilhelm-Johnen-Straβe University of Duisburg-Essen Faculty of Engineering

Friction drag primarily determines the total drag of transport systems. A promising approach to reduce drag at high Reynolds numbers(> 104) are active transversal surface waves in combination with passive methods like a riblet surface. For the application in transportation systems with large surfaces such as airplanes, ships or trains, a large scale distributed real-time actuator and sensor network is required. This network is responsible for providing connections between a global flow control and distributed actuators and sensors. For the development of this network we established at first a small scale network model based on Simulink and True Time. To determine timescales for network events on different package sizes we set up a Raspberry Pi based testbed as a physical representation of our first model. These timescales are reduced to time differences between the deterministic network events to verify the behavior of our model. Experimental results were improved by synchronizing the testbed with sufficient precision. With this approach we assure a link between the large scale model and the later constructed microcontroller based real-time actuator and sensor network for distributed active turbulent flow control.

关键词： Raspberry Pi True Time distributed actuator and sensor network network model

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The increased severity of acute pancreatitis in the elderly is mainly related to intestinal barrier dysfunction

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Hepatobiliary & Pancreatic Diseases International 2018年第6期17卷 575-577页

作者： marcel Cerqueira Cesar Machado Heraldo Possolo Souza Emergency Department Faculdade de Medicina Universidade de Sao Paulo

To the Editor:Severeacutepancreatitisintheelderlyischaracterizedby significantmorbidityandmortalityrates,withahigherfinancial impact when compared to the same disease in younger patients [1]. There are some obvious di... 详细信息

关键词： elderly severity younger populations older permeability translocation interleukin mucosal inflammation

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Spatiotemporal distribution of seasonal bird assemblages on land-bridge islands: linking dynamic and static views of metacommunities

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Avian Research 2019年第3期10卷 250-261页

作者： Chuanwu Chen marcel Holyoak Yanping Wang Xingfeng Si Ping Ding College of Life Sciences Zhejiang University Hangzhou 310020China Jiangsu Key Laboratory for Biodiversity and Biotechnology College of Life SciencesNanjing Normal University Nanjing 210046China Department of Environmental Science and Policy University of CaliforniaDavisCA 95616USA School of Ecological and Environmental Sciences East China Normal UniversityShanghai 200241China

Background: Although assessing temporal dynamics of populations is crucial for understanding metacommunities, empirical studies have primarily analyzed only static snapshots of communities. Here, we present a holistic view of how species traits and habitat characteristics relate to metacommunity dynamics and use it to test for differences in the spatiotemporal distribution of seasonal bird assemblages. Methods: We surveyed forest birds in breeding and winter seasons within 36 islands for 9 years. We then grouped birds into four landbird assemblages, selected on the basis of published differences in biology or ecology: winter residents, migratory winter visitors, breeding summer residents, and migratory summer visitors. We estimated dynamic species colonization and extirpation through the 9-year period, and evaluated the associations among island attributes, species attributes and community composition. Results: Overall, winter and summer residents showed strong associations between composition and habitat structure of the islands. In addition, winter and summer residents on large islands had lower extirpation and turnover than winter and summer visitors. Visitor assemblages showed no significant habitat associations, and in winter had high extirpation rates and small body sizes. By contrast, local extirpation of summer visitors was correlated with local species richness, indicating a likely effect of competition on extirpation. Conclusions: Our results demonstrated repeated patterns among species composition, bird traits, habitat/island characteristics and observed metacommunity dynamics. Winter and summer residents best matched species sorting and patch dynamics, respectively, due to differences in resource availability and requirements of overwinter survival versus breeding. Summer visitors were consistent with species sorting and winter visitors were randomly distributed, likely because of interactions with resident competitors. Our results highlight that coexist

关键词： Body size Colonization Competition Extirpation Island turnover Metacommunity

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