223 research outputs found
Fig. 4 in The effect of β-cyclocitral treatment on the carotenoid content of transgenic Marsh grapefruit (Citrus paradisi Macf.) suspension-cultured cells
No full textFig. 4. The effect of β-cc (0.5 mM) treatment on the carotenoid content and composition of transgenic citrus suspension-cultured cells at different growth stages. Error bars represent standard deviation (SD) of three biological replications.Published as part of Zheng, Xiongjie, Zhu, Kaijie, Ye, Junli, Price, Elliott J., Deng, Xiuxin & Fraser, Paul D., 2020, The effect of β-cyclocitral treatment on the carotenoid content of transgenic Marsh grapefruit (Citrus paradisi Macf.) suspension-cultured cells, pp. 1-8 in Phytochemistry (112509) 180 on page 4, DOI: 10.1016/j.phytochem.2020.112509, http://zenodo.org/record/819421
Yan yuan zi wo xiu yang.
No full text海普固特英譯 ; 鄭君里, 章泯同漢譯.附: 註釋斯坦尼斯拉夫斯基在莫斯科藝術劇場的工作年表術語對照表等.本電子書乃根據《香港版權條例(第528章)》而複製, 並只可在大學圖書館系統內的獨立電子書系統上使用.Haipugute Ying yi ; Zheng Junli, Zhang Min tong Han yi.Ben dian zi shu nai gen ju "Xianggang ban quan tiao li (Di 528 zhang)" er fu zhi, bing zhi ke zai da xue tu shu guan xi tong nei de du li dian zi shu xi tong shang shi yong.Fu: Zhu shi Sitannisilafusiji zai Mosike yi shu ju chang de gong zuo nian biao shu yu dui zhao biao deng
Bridging the gap between research and practice: construction and validation of a CDA-informed English reading test for China's twelfth graders
No full textAssessment should be made more useful for promoting students' learning success. Although recent research advances in cognitive diagnostic assessment (CDA) move in this direction, most CDA studies of second language (L2) reading tend to identify examinees' mastery of skills by using the existing tests that were not originally designed for diagnostic purposes (e.g., Buck, Tatsuoka, & Kostin, 1997; Kasai, 1997).This has led to inaccurate and/or unsatisfactory diagnostic inferences, as many skills are rarely, if ever, measured in such tests (e.g., Alderson, 2010; Jang, 2009).
By constructing a CDA-informed test, this study aims to diagnose Chinese twelfth graders' strengths and weaknesses in reading comprehension, and thus contribute to enhanced instruction and learning. Approximately 1,311 students and their English teachers from one high schools in China participated in this research . Using Cognitive Design System (CDS) approach (Embretson, 1994, 1998), this study integrated a cognitive framework from the outset into the whole test development primarily concerning three key issues: what to diagnose, how to diagnose, and how to use the diagnostic information. An integrated mixed methods research design (Greene, 2007) was developed over the following four phases to address the issues.
In the first stage, this study built a cognitive model, identified eight skills, and specified their hierarchical relationships. The cognitive model was built and iteratively refined by integrating information from a thorough literature review, students’ think-aloud protocols, and opinions from content experts. The results from the statistical analysis also demonstrate that the cognitive model is appropriate for this study, since the value of hierarchy consistency index (HCI) is .66, and about 60% of the variance on item difficulty in the regression analysis can be explained by the skills specified in the model. In the second stage, the test specifications were designed to provide a generative requirement for creating test tasks, and the Q matrix was for guiding the writing of each specific item. Thirty multiple-choice items were initially created and refined iteratively through pilot tests.
Then, at the third and fourth stage, the test response data were analyzed, and both quantitative and qualitative evidence was used to support test inferences. Quantitatively, the response data was first analyzed in the conventional Reparametrized Unified Model (RUM), then in the reduced Re-parameterized Unified Model (r-RUM) by incorporating the attribute hierarchy in data analysis (i.e., the new model was referred to as the rRUM-AH). As presented in the empirical and simulation studies, both the MCMC chain and burn-in period were shorter in the rRUM-AH than the RUM, indicating that it is comparatively easier to get converged in the rRUM-AH than the RUM. In addition, the model-data fit and skill classification accuracy in the rRUM-AH were compared to several other cognitive diagnostic models (CDMs) with attribute hierarchy to determine which model was best for this study. Furthermore, qualitative evidence (e.g., interviews, classroom observations, and surveys) was collected for the evaluation of diagnostic feedback on learning.
Situated at the intersection of theories of L2 reading, cognition, and measurement, this dissertation project narrates a validation process for developing a CDA-informed English reading test. Thus it strengthens validity arguments and enhances understanding of the complexity of CDA test construction. As one of the first to develop a CDA-informed L2 reading test, this study is also unique in incorporating the hierarchical structures of the reading skills in test design, development and validation.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2018-08-01The student, Junli Wei, accepted the attached license on 2016-07-12 at 12:36.The student, Junli Wei, submitted this Dissertation for approval on 2016-07-12 at 12:38.This Dissertation was approved for publication on 2016-07-13 at 09:28.DSpace SAF Submission Ingestion Package generated from Vireo submission #9890 on 2016-11-10 at 12:20:31Made available in DSpace on 2016-11-10T18:27:47Z (GMT). No. of bitstreams: 4
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Previous issue date: 2016-07-13Embargo set by: Seth Robbins for item 95363
Lift date: 2018-11-10T18:28:02Z
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Label-free electrochemical impedance detection of kinase and phosphatase activities using carbon nanofiber nanoelectrode arrays
No full textWe demonstrate the feasibility of a label-free electrochemical method to detect the kinetics of phosphorylation and dephosphorylation of surface-attached peptides catalyzed by kinase and phosphatase, respectively. The peptides with a sequence specific to c-Src tyrosine kinase and protein tyrosine phosphatase 1B (PTP1B) were first validated with ELISA-based protein tyrosine kinase assay and then functionalized on vertically aligned carbon nanofiber (VACNF) nanoelectrode arrays (NEAs). Real-time electrochemical impedance spectroscopy (REIS) measurements showed reversible impedance changes
upon the addition of c-Src kinase and PTP1B phosphatase. Only a small and unreliable impedance variation was observed during the peptide phosphorylation, but a large and fast impedance decrease was observed during the peptide dephosphorylation at different PTP1B concentrations. The REIS data of dephosphorylation displayed a well-defined exponential decay following the Michaelis–Menten heterogeneous enzymatic model with a specific constant, k[subscript]c[subscript]a[subscript]t/K[subscript]m, of (2.1 ± 0.1) × 10[superscript]7 M[superscript]−[superscript]1 s[superscript]−[superscript]1. Consistent values of the specific constant was measured at PTP1B concentration varying from 1.2 to 2.4 nM with the corresponding electrochemical signal decay constant varying from 38.5 to 19.1 s. This electrochemical method can be potentially used as a label-free method for profiling enzyme activities in fast reactions
Electrochemical protease biosensor based on enhanced AC voltammetry using carbon nanofiber nanoelectrode arrays
No full textWe report an electrochemical method for measuring the activity of proteases using nanoelectrode arrays (NEAs) fabricated with vertically aligned carbon nanofibers (VACNFs). The VACNFs of ~150 nm in diameter and 3 to 5 μm in length were grown on conductive substrates and encapsulated in SiO[subscript 2] matrix. After polishing and plasma etching, controlled VACNF tips are exposed to form an embedded VACNF NEA. Two types of tetrapeptides specific to cancer-mediated proteases legumain and cathepsin B are covalently attached to the exposed VACNF tip, with a ferrocene (Fc) moiety linked at the distal end. The redox signal of Fc can be measured with AC voltammetry (ACV) at ~1 kHz frequency on VACNF NEAs, showing distinct properties from macroscopic glassy carbon electrodes due to VACNF’s unique interior structure. The enhanced ACV properties enable the kinetic measurements of proteolytic cleavage of the surface-attached tetrapeptides by proteases, further validated with a fluorescence assay. The data can be analyzed with a heterogeneous Michaelis-Menten model, giving “specificity constant” k[subscript cat]/K[subscript m] as (4.3 ± 0.8) x 10[superscript 4] Mˉ¹sˉ¹ for cathepsin B and (1.13 ± 0.38) x 10[superscript 4] Mˉ¹sˉ¹ for legumain. This method could be developed as portable multiplex electronic techniques for rapid cancer diagnosis and treatment monitoring
Syntheses, neural protective activities, and inhibition of glycogen synthase kinase-3beta of substituted quinolines.
No full textA new series of fifteen 5-, 6-, and 8-appended 4-methylquinolines were synthesized and evaluated for their neural protective activities. Selected compounds were further examined for their inhibition of glycogen synthase kinase-3β (GSK-3β) and protein kinase C (PKC). Two most potent analogs, compounds 3 and 10, show nanomolar protective activities in amyloid β-induced MC65 cells and enzymatic inhibitory activities against GSK-3β, but poor PKC inhibitory activities. Using normal mouse model, the distribution of the most potent analog 3 in various tissues and possible toxic effects in the locomotors and inhibition of liver transaminases activities were carried out. No apparent decline of locomotor activity and no inhibition of liver transaminases were found. The compound appears to be safe for long-term use in Alzheimer’s disease mouse model
Chemically derived ziconia toughened alumina via sol-gel processing, 1997
No full textSol-gel processing methods were used to prepare ZTA ceramic powders from high purity materials. The precursor systems used for this research were zirconium butoxide, zirconium isopropoxide, alumium tri-sec butoxide, and yttrium isopropoxide. Other reagents were also used. The emphasis was on mixing the precursor system, performing aging experiments, and heat treatment studies to prepare the final ZTA ceramics. The effects of processing conditions on the sol to gel transition were examined by varying the water ratios, the ZTA precursor composition and the molar ratio of TEA/alkoxide. It was observed that the TEA/alkoxide molar ratio played an important role in the time for gel formation. The presence of poorly hydrolyzable ligands slows down the hydrolysis condensation process. The total amount of water for hydrolysis had an effect on the time of gel-formation. Rheological measurements made during the aging process indicated an increase in viscosity with aging time, which was consistent with changing structure. XRD was used to determine the phase composition after heat treatment. From XRD diagram, alumina is transformed into the a phase after calcination at 1200�C, the tetragonal 7I02 phase was retained on cooling to room temperature in the mixture containing. TG/DTA was also used to deteramine optimum heating schedules. In the presene of zirconia, the alumina phase transformation takes place at a considerably higher temperature than in pure alumina, the more volume percent of Z1O2, the higher the transformation temperature
The mechanism of ovarian cancer chemoresistance
No full textOvarian cancer (OC) is the leading cause of female reproductive tract cancer mortality in the world. Although cytoreductive surgery followed by platinum/taxane acts a standard therapy and contributes to a high initial response rate, most patients will ultimately develop tumour recurrence and succumb to chemoresistant disease. Therefore, improved targeting therapies and chemosensitisation strategies are essential for reducing the mortality of this devastating malignancy.
This thesis investigates roles of epithelial-mesenchymal transition (EMT), cancer stem cells (CSC), as well as the PI3K/Akt/mTOR signalling pathway in OC chemoresistance, and provides a range of potential candidate chemoresistant biomarkers with proteomic technologies.
The aims of this study were to: 1) compare the expression differences of EMT, CSC and PI3K/Akt/mTOR pathway related biomarkers between the chemosensitive and the corresponding chemoresistant cell lines, and identify whether they are related to OC chemoresistance; 2) investigate the treatment effect of a dual PI3K/Akt/mTOR pathway inhibitor (BEZ235) on OC chemoresistant cell lines, and explore the potential mechanism involved; 3) identify novel potential OC chemoresistant biomarkers with the application of proteomics technology; 4) study the expression of the selected biomarkers on human OC tissues, which includes EMT, CSC and PI3K/Akt/mTOR pathway related biomarkers, as well as the identified potential chemoresistant biomarkers in proteomics experiment, and correlate the expression levels with clinical statistics.
The results indicate that EMT, CSC and PI3K/Akt/mTOR pathway play a critical role in OC chemoresistance, which is further confirmed on human OC tissues. The inhibition of the PI3K/Akt/mTOR pathway eliminates the subpopulation with CSC characteristics, reverses EMT, and increases the chemosensitivity to cisplatin in chemoresistant OC cell lines. In addition, some novel candidate chemoresistant biomarkers were identified by proteomic technologies and further confirmed by validation study.
In conclusion, this study revealed the critical role of EMT, CSC and PI3K/Akt/mTOR pathway, and provided a promising targeted therapy strategy with the PI3K/Akt/mTOR pathway inhibitor. In addition, the novel chemoresistant biomarkers identified could also have an import impact on the prognosis and treatment of OC chemoresistance in the future
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