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Rheological and Thermal Behavior of High-density Polyethylene (HdPE) at different Temperatures

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Materials Sciences and Applications 2014年第13期5卷 923-931页

作者： cynthia d’avila carvalho erbetta Getúlio F. Manoel Ana Paula Lelis Rodrigues Oliveira Maria Elisa Scarpelli Ribeiro e Silva Roberto Fernando Souza Freitas Ricardo Geraldo Sousa Polymer Science and Technology Laboratory Chemical Engineering Department Engineering School Federal University of Minas Gerais Belo Horizonte Brazil

In the present work, rheological properties of HdPE samples were measured at temperatures of 150°C, 190°C and 230°C. It was shown, by oscillatory tests, at low frequencies, that, for temperatures of 150°C and 190°C, there was a predominance of the viscous behavior over the elastic one. At 230°C, there was a predominance of the elastic contribution, and there was an increase of the molar mass compared with the ones obtained from the tests at 150°C and 190°C. The results obtained from the temperature ramp oscillatory test showed that, up to around 248°C, the viscous behavior prevailed, the opposite being observed at higher temperatures. At 230°C the sample showed significantly lower values of strain when compared with the ones observed at 150°C and 190°C. Oxidative induction time (OIT), melting point and degree of crystallinity were determined by differential scanning calorimetry (dSC). The dSC results and the rheological measurements showed a completely different behavior for the HdPE samples at 230°C compared with the 150°C and the 190°C ones, suggesting that HdPE, at the temperature of 230°C, underwent thermo-oxidative degradation with the initial predominance of crosslinking.

关键词： HdPE Rheology degradation dSC FTIR

Cerium alleviates drought-induced stress in Phaseolus vulgaris

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Journal of Rare Earths 2020年第3期38卷 324-331页

作者： Olívia Graziela Gelioli Salgado Jéssica Cristina Teodoro Joyce Pereira Alvarenga cynthia de Oliveira Teotonio Soares de carvalho débora domiciano Paulo Eduardo Ribeiro Marchiori Luiz Roberto Guimaraes Guilherme department of Soil Science Federal University of LavrasCP 3037Campus UFLALavras37200-000Brazil department of Biology Federal University of LavrasCP 3037Campus UFLALavras37200-000Brazil

Extreme drought events are expected to be one of the main challenges for tropical agriculture and,consequently,for global food *** this reason,it is urgent to develop strategies to increase water use efficiency,as well as to increase crops’ ability to cope with *** rare earth elements(REEs) are known to alleviate damages in plants under abiotic stresses,we hypothesized that addition of Ce^3+to nutrient solution would promote the growth of common bean,especially under simulated drought *** test this hypothesis,we conducted an experiment evaluating the effect of six Ce^3+concentrations on the development and physiological traits of common bean grown in nutrient solution under normal condition and under induced drought stress,caused by the addition of polyethylene glycol6000 to the nutrient *** results show that Ce^3+alleviates water stress in common bean plants,increasing their survival rate and *** addition,Ce^3+application increases photosynthesis rate,chlorophyll content and water use efficiency under water ***,we observe no significant effect of Ce^3+on plants growing under normal ***,Ce3+seems to be a promising attenuator of drought stress for common bean.

关键词： Water stress Polyethylene glycol Rare earth elements Cerium nitrate Mitigation Common bean

Rheological Study of Polymers Used as Viscosity Index Improvers for Automotive Lubricant Oils

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Journal of Modern Physics 2014年第12期5卷 1085-1093页

作者： Ana Paula Pena Almeida Ana Paula Lelis Rodrigues de Oliveira cynthia d’ávila carvalho erbetta Ricardo Geraldo de Sousa Roberto Fernando de Souza Freitas Maria Elisa Scarpelli Ribeiro e Silva Polymer Science and Technology Laboratory Chemical Engineering Department Engineering School Federal University of Minas Gerais Belo Horizonte Brazil

In this work, a rheological study of automotive lubricant oils, neutral light paraffinic (NLP) and neutral medium paraffinic (NMP), additivated with two commercial viscosity index improvers-VIIs, based on hydrogenated poly (isoprene-co-styrene), at different concentrations, was carried out. The study included the determination of the kinematic viscosity of the mixtures, the calculation of the viscosity indexes and their behavior when subjected to various rheometric experiments, including stress sweep, steady state flow, creep and recovery, and temperature ramp oscillatory tests. The obtained results showed the efficacy of the additives as viscosity index improvers, enabling a significant increase in the viscosity index of the pure oils at relatively low concentrations. The determination of the storage (G’) and of the loss (G”) moduli for the mixtures oil/VII additives showed a large predominance of the viscous effect over the elastic one. Except when under low shear stress, the mixtures showed a pseudoplastic behavior, with the flow curves being adjusted to fit the Ostwald-de-Waele model (Power Law), with negative flow behavior indexes.

关键词： Viscosity Index Improvers Automotive Lubricants Rheology Viscosity Index Polymer Additives

Characterization of the Stem Cell Fraction in Pancreatobiliary Carcinomas: The Notch Signaling Pathway as a Potential Therapeutic Target

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Journal of Cancer Therapy 2018年第6期9卷 480-502页

作者： Elisabeth Seidel cynthia de carvalho Fischer Christopher Neumann Anja Reutzel-Selke Andreas Andreou Joseph Gassner Julia Gogolok Peter Tang Anja Schirmeier Fritz Klein Igor M. Sauer Johann Pratschke Marcus Bahra Rosa B. Schmuck Charité—Universitatsmedizin Berlin Corporate Member of Freie Universitat Berlin Humboldt-Universitatzu Berlin and Berlin Institute of Health Institute of Surgery Augustenburger Platz 1 Berlin Germany

Pancreatic adenocarcinoma (PdAC) and extrahepatic cholangiocarcinoma (ECC) are highly lethal malignancies with limited treatment options. Both a small subpopulation of cancer stem cells (CSC) and the deregulation of the notch pathway have been considered potential sources of tumor formation. In this study, flow cytometry (FCM) was conducted to identify the CSC population and Notch-associated proteins in ECC and PdAC cell lines. Additionally, the treatment effect of Gemcitabine and the specific notch-inhibitor dAPT on ECC and PdAC cell lines was evaluated. Our results show that the amount of SP cells in ECC cell lines is significantly higher than in PdAC cell lines, and that SP-ECC cells show a higher sensitivity to therapy. In conclusion, inhibition of Notch signaling with dAPT may be of therapeutic value in ECC, but seems to show no effect on more aggressive PdAC. As it could be essential for the improvement in outcomes of the ECC patients, other trials are needed to determine the role of further Notch components.

关键词： Notch Pathway Cancer Stem Cells Pancreatic Adenocarcinoma Extrahepatic Cholangiocarcinoma Targeted Therapy

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重症先天性肌无力综合征的产科和麻醉管理

麻醉与镇痛 2009年第5期5卷 85-87页

作者： Nico Terblanche cynthia Maxwell Johannes Keunen Jose C. A. carvalho FANZCA, FRCPC 俞欣(译) 方向明(校) departments of Anesthesia and Pain Management departments of Obstetrics and Gynecology Mount Sinai Hospital University of Toronto Toronto Canada 不详

先天性肌无力综合征是一组表现为神经肌肉传递障碍的异质性遗传疾病。尽管它与后天免疫性重症肌无力综合征具有共同特征——肌肉疲劳，但两者在病理生理、诊断、治疗和病程进展等方面存在着不同。本文报道1例28岁先天性肌无力综合征的... 详细信息

先天性肌无力综合征是一组表现为神经肌肉传递障碍的异质性遗传疾病。尽管它与后天免疫性重症肌无力综合征具有共同特征——肌肉疲劳，但两者在病理生理、诊断、治疗和病程进展等方面存在着不同。本文报道1例28岁先天性肌无力综合征的产妇，在腰麻下行择期剖宫产术。患者由于肌力失衡和肌力减弱致脊柱侧弯和慢性呼吸衰竭，麻醉医师在超声引导下完成腰麻操作，手术中给予无创正压通气保持肺容积、有效地防止呼吸功能的恶化。

关键词：先天性肌无力综合征麻醉管理重症产科神经肌肉传递择期剖宫产术慢性呼吸衰竭无创正压通气

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年轻视网膜中央静脉阻塞患者的临床进程

眼科新进展 2005年第3期25卷 200-200页

作者： Franco M.Recchia cynthia A.carvalho-Recchia Tarek S.Hassan

目的描述55岁以下的视网膜中央静脉阻塞(CR-VO)患者的临床进程。设计和方法回顾性非比较性的连续病例分析。复习了67例患者的人口统计学、影像、临床和视力数据。对其中随访6个月以上(平均29.2个月)的病例资料进行了统计学分析。主要结... 详细信息

目的描述55岁以下的视网膜中央静脉阻塞(CR-VO)患者的临床进程。设计和方法回顾性非比较性的连续病例分析。复习了67例患者的人口统计学、影像、临床和视力数据。对其中随访6个月以上(平均29.2个月)的病例资料进行了统计学分析。主要结果测定最佳矫正视力和眼内新生血管形成的发病率。结果在连续的67例(男性55%,平均年龄45岁)患者中,视力平均为20/50。其中45例(67%)患者被查出至少有1种全身性疾病。在57例随访6个月以上的患者中,最终视力20/40(含)以上的占42%,20/50-20/100的占18%,20/200(含)以下的占40%.在CRVO发病的3-6个月内,绝大部分患者出现了视力减退。在发病的12个月以后,出现视力提高的极少见。就诊视力在20/40(含)以上的22例患者中,36%的患者在最近的1次检查中视力下降到了20/400甚至更低。就诊视力在20/200-20/400的10例患者中,8例视力提高到20/60甚至更高。就诊视力在数指或者更差的6例患者中,没有1例视力得到改善。在CRVO发病的1-9个月内,10例(18%)患者被诊断为眼内新生血管形成。其中前节新生血管形成的患者有6例(11%),包括3例(5%)新生血管性青光眼。新生血管形成的发生与患者的性别、年龄、有无伴随疾病、症状的持续时间和就诊视力均没有明显关系。结论年轻患者的CRVO有着多变的临床过程?

关键词：视网膜中央静脉阻塞新生血管患者视力 CRVO 进程