419 research outputs found
Yi tai er yang hua tai de zhi bei he biao zheng ji qi zai guang cui hua zhong de xing neng fen xi
No full textDing, Zhimin = 遺態二氧化鈦的製備和表徵及其在光催化中的性能分析 / 丁志敏.Thesis (M.Phil.)--Chinese University of Hong Kong, 2011.Includes bibliographical references.Abstracts in English and Chinese.Ding, Zhimin = Yi tai er yang hua tai de zhi bei he biao zheng ji qi zai guang cui hua zhong de xing neng fen xi / Ding Zhimin.ABSTRACT --- p.i摘要 --- p.iiiAcknowledgement --- p.vTable of Contents --- p.viList of Figures --- p.ixList of Tables --- p.xiiiChapter Chpater 1 --- Introduction --- p.1Chapter 1.1 --- Titanium dioxide --- p.1Chapter 1.1.1 --- Lattice structure --- p.2Chapter 1.1.2 --- Phase transition --- p.3Chapter 1.1.3 --- Energy band structure --- p.4Chapter 1.1.3.1 --- Band structure of titanium dioxide --- p.4Chapter 1.1.3.2 --- Quantum size effect --- p.6Chapter 1.1.4 --- Principle of photocatalysis --- p.8Chapter 1.1.5 --- Improvement of the TiO2 photocatalyst --- p.10Chapter 1.1.5.1 --- Noble metal deposition --- p.10Chapter 1.1.5.2 --- Coiq)led semiconductor --- p.11Chapter 1.1.5.3 --- Ion doping --- p.12Chapter 1.2 --- Biomorphic materials --- p.13Chapter 1.3 --- Cotton template --- p.14Chapter 1.3.1 --- Composition of cotton --- p.14Chapter 1.3.2 --- Cotton structure --- p.15Chapter 1.4 --- Methyl orange --- p.16Chapter 1.5 --- Objectives and thesis layout --- p.18References --- p.19Chapter Chapter 2 --- Methodology and Instrumentation --- p.27Chapter 2.1 --- Sample preparation --- p.27Chapter 2.1.1 --- Template and precursors --- p.27Chapter 2.1.2 --- Synthesis of the Ti02-TTIP samples --- p.28Chapter 2.1.2.1 --- Methodology --- p.28Chapter 2.1.2.2 --- Fabrication procedures --- p.31Chapter 2.1.3 --- Synthesis of the TiO2-TALH samples --- p.32Chapter 2.1.3.1 --- Methodology --- p.32Chapter 2.1.3.2 --- Fabrication procedures --- p.33Chapter 2.2 --- Characterization --- p.33Chapter 2.2.1 --- Scanning electron microscope (SEM) --- p.33Chapter 2.2.2 --- Transmission electron microscope (TEM) --- p.34Chapter 2.2.3 --- Raman spectroscopy (RS) --- p.34Chapter 2.2.4 --- X-ray diffractometry (XRD) --- p.34Chapter 2.2.5 --- Thermo gravimetric analysis (TGA) --- p.35Chapter 2.2.6 --- Differential thermal analysis (DTA) --- p.36Chapter 2.2.7 --- Ultraviolet-visible spectroscopy (UV-vis) --- p.36Chapter 2.3 --- Photocatalytic performance --- p.37Chapter 2.3.1 --- Lambert-Beer's law --- p.37Chapter 2.3.2 --- "Verification of Beer,s Law" --- p.38Chapter 2.3.3 --- Photocatalytic evaluation procedures --- p.39Chapter 2.3.3.1 --- Glass beaker --- p.39Chapter 2.3.3.2 --- Quartz vessel --- p.40References --- p.41Chapter Chapter 3 --- Results of Characterizations --- p.43Chapter 3.1 --- Characterization of Ti02-TTIP --- p.43Chapter 3.1.1 --- Effect of calcination temperature on the samples --- p.43Chapter 3.1.1.1 --- DTA and TGA results --- p.43Chapter 3.1.1.1.1 --- Pure cotton --- p.43Chapter 3.1.1.1.2 --- Sol-infiltrated cotton --- p.45Chapter 3.1.1.2 --- XRD results --- p.47Chapter 3.1.1.3 --- Raman spectra results --- p.51Chapter 3.1.1.4 --- SEM results --- p.54Chapter 3.1.2.5 --- TEM results --- p.58Chapter 3.1.1.6 --- UV-visible absorption spectra --- p.60Chapter 3.1.2 --- Effect of calcination duration on the properties of samples --- p.61Chapter 3.1.2.1 --- XRD results --- p.62Chapter 3.1.2.2 --- Raman spectra results --- p.65Chapter 3.2 --- Characterization ofTiO2 -TALH --- p.67Chapter 3.2.1 --- DTA and TGA results --- p.67Chapter 3.2.2 --- XRD results --- p.69Chapter 3.2.3 --- Raman spectra results --- p.72Chapter 3.2.4 --- SEM results --- p.73Chapter 3.2.5 --- TFM rpcnltc --- p.76Chapter 3.2.6 --- UV-visible absorption spectra --- p.78References --- p.79Chapter Chapter 4 --- Photocatalytic Performance --- p.81Chapter 4.1 --- Verification of Beer's Law --- p.81Chapter 4.2 --- Photocatalytic results --- p.82Chapter 4.2.1 --- MO solution contained by glass beaker --- p.83Chapter 4.2.2 --- MO solution contained by quartz vessel --- p.86Chapter 4.2.3 --- Photocatalytic performance of TiO2-TALH sample prepared at 600°C --- p.90Chapter 4.3 --- Discussions --- p.92References --- p.94Chapter Chapter 5 --- Conclusions and Future Works --- p.95Chapter 5.1 --- Conclusions --- p.95Chapter 5.2 --- Future works --- p.98References --- p.9
Processing optimisation, molecular characterisation, and anti-cancer activities of arabinoxylans extracted from corn bran in vitro
No full textBackground: Arabinoxylans (AXs) are the main non-starch polysaccharides that widely exist in by-products of cereal processing. The anti-cancer activities, such as inhibiting cancer cell proliferation and promoting apoptosis, of AXs which are extracted from various cereal materials have been reported recently. However, the possible relationship between the structures and anti-cancer activities of AXs have not yet been established and proposed. The anti-cancer mechanisms of AXs are unknown. The aims of this study were to develop and optimise the AXs combined extraction treatment from selected cereals, characterise the molecular structure and measure the anti-cancer activities of AXs extracts in vitro to explore the possible relationship between their structures and anti-cancer activity, and propose the potential mechanisms.
Methods: The alkaline (A) extraction method, hydrothermal (H) extraction method, and a low concentration alkaline-assisted hydrothermal (LAH) extraction method were used to extract AXs from cereal materials. The high-performance liquid chromatography (HPLC) methods were used to characterise the molecular structure and monocular composi6on of extracted AXs. The anti-cancer effects of extracted AXs on the viability, proliferation cycle and apoptosis of human gastric adenocarcinoma cell line (AGS) cells were assessed in vitro using flow cytometry. The mRNA expressions of selected genes related to cell growth and apoptosis control were measured by RT-qPCR analysis and the protein expressions were tested by Western blot assay.
Results: Under the optimum extraction condi6ons of LAH, the extraction rate of AXs reached 33.31%, which is about 7 6mes of H extraction (4.65%) and no significant difference when compared with that of A-AXs (32.34%) (p ≥ 0.05). Compared to molecular characteristics of AAXs., LAH-AXs extracts have a lower percentage (23.68%) of low molecular weight range (0.01KDa to 10.00KDa), which is 29.71%, and a higher ferulic acid (FA) content (0.64 mg/g), which is 7 6mes compared to A-AXs (0.09mg/g). In vitro studies showed that both LAH-AXs and A-AXs at optimised concentra6on of 50 μg /ml were able to significantly inhibit the proliferation of AGS and significantly promote apoptosis in AGS cells in 24 hrs treatment (p ≤0.05). Furthermore, in the examination of the mechanism of AXs anti-cancer activities, the cell cycle analysis results demonstrated that both LAH-AXs and A-AXs treatment significantly increased the accumula6on of AGS cells in the S phase, which is 1.4-fold compared with negative control (p ≤ 0.05). Furthermore, both LAH-AXs and A-AXs significantly up-regulated the mRNA expressions of cyclin-dependent kinase (CDK) inhibitor p21 and pro-apoptosis genes Bad and Bid. Differently, LAH-AXs significantly up-regulated caspase-8 mRNA expression (2.33-fold) and pERK protein expression levels (1.4-fold) compared with negative control (p ≤ 0.05), whereas A-AXs did not show a significant impact in this regard.
Conclusions: At optimal conditions for LAH-AXs-C extraction, the extraction rate can reach levels comparable to those achieved with high alkaline concentrations (8%). Molecular characterisations indicate variations in molecular distribution, molecular composition and FA content between LAH-AXs-C and A-AXs-C. The distinct effects of LAH-AXs-C and A-AXs-C on the cell cycle arrest occurring at different stages. A decrease in cell viability and induction of apoptosis in AGS cells, may be attributed to the differences in their structures. The underlying mechanisms of their anti-cancer activities possibly involve regulation through the Bcl-2 family signalling pathway and the ERK signalling pathway, which are suggested by the up-regulation of mRNA expressions level of p21 and the pro-apoptosis genes Bad, Bid and protein pERK. Moreover, the upregulation in caspase-8 (2.33-fold) expression indicates the activation of extrinsic pathway. This study optimised the extraction method for AXs, which significantly increased the extraction rate (р≤0.05). It also characterised the structure of AXs and explored their potential anti-cancer effects, providing an initial understanding of the relationship between the structure and bioactivities of AXs at the molecular level
Cross-Section of Returns, Predictors Credibility, and Method Issues
No full textThe paper focuses on the relationship between firms’ characteristics and cross-section returns. The author reviews and critically assesses the most recent contributions in the literature. After comparing the abnormal returns (Alpha) and t statistics of the original works with those of replication works, the author concludes that 94 characteristics are robust. The limitation of the paper is that measurement errors in the COMPUSTAT could affect the predictability of cross-section returns. The practical implication of the paper is that the author validates the practice of fundamental analysis. Investors could benefit from those discovered characteristics. The author validates the policy consequence and connects the theoretical frameworks with empirical results. The author evaluates the empirical methodology and proposes several methods to improve future research
Financial Report Readability and Accounting Conservatism
No full textAccounting conservatism could affect the quantitative information on a financial statement. In this paper, the author focuses on qualitative information on financial statements. The author investigates the association between financial report readability and accounting conservatism and uses the FOG index to measure financial report readability. By using management discussion and analysis (MD&A) from 1996 to 2019, the author finds that financial report readability is positively associated with accounting conservatism. Additionally, the author separates the samples into high-compensation incentive and low-compensation incentive subsamples. The results show that the above association is stronger in the high-compensation incentive samples than in the low-compensation incentive samples. This result implies that accounting conservatism could mitigate managerial opportunism in the qualitative disclosure setting
Visible Light–Excited Pt(II) Acetylide Complexes Bearing red Emission: Synthesis, Characterization, X‐Ray Structure Analysis, Photoluminescence, and TD‐DFT Investigations
No full textThe advancement of visible-light harvesting Pt(II) complexes with extended excited state lifetimes is crucial, as these properties are essential for their applications in photocatalysis, nonlinear optics, photodynamic therapy, among other areas. In this study, we synthesized platinum complexes with main ligands bearing sulfur (S) donor atoms, which not only shifted the absorption into the visible range but also increased the excited state lifetimes in solution as well as in solid state. In this context, two series of platinum complexes (C1a–C6a and C1b–C6b) were synthesized in excellent isolated yields in a single step reaction catalyzed by CuI in the presence of base from precursor complexes (PC1a–PC6a and PC1b–PC6b) bearing chloride ancillary ligand. These complexes were characterized by multiple analytical techniques, among them five complexes (C1a, C5a, C6a, C2b, and C6b) were analyzed in solid state by single crystal X-ray analysis that showed the exact orientation of the ligands around Pt and intramolecular/intermolecular bonding in these complexes. The solid-state structure demonstrated dimeric structures interacting through noncovalent π⋯π stacking that could be responsible for extended lifetime, longer wavelength emission, and phosphorescence. These complexes absorbed mainly around 240 to 260 and 420 to 500-nm visible region assigned to ligand–ligand charge transfer (LLCT) and metal-to-ligand charge transfer (MLCT), respectively. The photoluminescence was observed in 630-nm region when excited at 450-nm visible wavelength in both solution and solid state. The absorption and emission properties of all these complexes were further investigated by time-dependent density functional theory (TD-DFT) calculations that rationalized the effect of different constituents on the main SNO donor ligand. The strong absorption in the visible region and emission in the near-infrared (NIR) region in both solid and solution state suggested that these complexes could have potential applications in various fields of optoelectronics, materials science, and photodynamic therapy
A video camera recording method for measuring terminal velocity of seed dispersal by wind
No full textAn accurate and convenient method is essential for measuring the terminal velocity of seeds dispersed by wind. Systematic and random errors produced by existing methods lower the accuracy and convenience in determining seed terminal velocity. In this study, a video camera was used to record the falling process of forty-one species of wind-borne seed with eight appendage structures and seven aerodynamic behaviors in a settling tower at a speed of 50 frames per second (fps). The videos were analyzed by Quick Time Player to determine seed acceleration height, acceleration time, and terminal velocity. The results showed that acceleration height and time, terminal velocity, and the difference between terminal velocity and descent velocity (DTD) increased with wing loading. Compared with dropping methods, the camera recording method eliminated the effect of acceleration and corrected seed terminal velocity. Based on wing loading, release heights were determined for accurate measurement of terminal velocity of different seeds. This method, due to its inexpensive equipment, high accuracy, easy observation and operation, can be applied to measure the terminal velocity of wind dispersed seeds, and provides a promising method in exploring the dispersal process of seeds.Fil: Liu, Minghu. Chinese Academy Of Forestry; ChinaFil: Xin, Zhiming. Chinese Academy Of Forestry; ChinaFil: Su, Zhi. Chinese Academy Of Forestry; ChinaFil: Zhao, Yingming. Chinese Academy Of Forestry; ChinaFil: Li, Xinle. Chinese Academy Of Forestry; ChinaFil: Liu, Zhimin. Chinese Academy of Sciences; República de ChinaFil: Cony, Mariano Anibal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; ArgentinaFil: Liang, Wei. Chinese Academy of Sciences; República de ChinaFil: Qin, Xuanping. Chinese Academy of Sciences; República de ChinaFil: Qian, Jianqiang. Henan Agricultural University; ChinaFil: Cui, Xue. Station Of Forest And Grassland Pest Control And Quarantine; ChinaFil: Zhou, Quanlai. Chinese Academy of Sciences; República de Chin
Laman xiao ying yin qi de zi xuan-gui dao ou he leng bo se yuan zi zhi you guan ke ti
No full textCheung, Chi Man = 拉曼效應引起的自旋-軌道耦合冷玻色原子之有關課題 / 張智敏.Thesis M.Phil. Chinese University of Hong Kong 2014.Includes bibliographical references (leaves 62-66).Abstracts also in Chinese.Title from PDF title page (viewed on 20, December, 2016).Cheung, Chi Man = Laman xiao ying yin qi de zi xuan-gui dao ou he leng bo se yuan zi zhi you guan ke ti / Zhang Zhimin
High production of glutathione by in vitro enzymatic cascade after thermostability enhancement
No full textEnvironmental Catalysis and the Corresponding Catalytic Mechanism
No full textThis eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contac
The Study on the Curriculum Setting and Characteristics of Cambridge Undergraduate Philosophy Major
No full textEducation of philosophy is both an old and new topic. It is an important approach for human thoughts propagation and theoretical studies. At theUniversityofCambridge, philosophy teaching and learning activities have been existed for 804 years, born at the same time with the university. . This thesis aims to examine the developmental process of philosophy education at the undergraduate level,, to investigate the curriculum of philosophy education of the latest ten years, and to summarize the characteristics of philosophy education at the University of Cambridge
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