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Cash holdings, corporate governance and firm performance in hospitality industry / Kwan Jing Hui
Get PDFThis thesis consists of three essays on corporate cash holdings. The central theme of the dissertation is to study the impact of internal and external corporate governance mechanisms on firms’ corporate cash management policy, and firm performance in the hospitality industry. The first essay of the dissertation examines the determinants of cash holdings using a sample of public listed hospitality firms in Malaysia firms from year 2002 to 2013. The non-parametric Wilcoxon-Mann-Whitney test was carried out to examine the time and sectoral differences in cash holdings. In addition, the panel regression techniques are used to investigate the relationships between firm characteristics and level of corporate cash holdings. The result revealed that larger and higher leveraged companies have lesser cash. Similarly, capital expenditures and liquid assets substitutes are found to have a negative effect on the level of cash. However, the cash flow, cash flow variability, growth opportunities and, dividend dummy were found to have a positive relationship with cash holdings decision. The result shows that cash holdings theories such as trade-off theory, the pecking order theory, and the agency theory, help explain corporate cash holdings behaviour of firms in emerging market, such as Malaysia. Besides, the findings show a significant impact of the tourism crisis on cash holdings in the industry. The second essay studies the relationships between corporate governance mechanisms and cash holdings, and joint effects on firm performance at the firm level. Using a panel data analysis of a sample of public listed hospitality firms in Malaysia and Singapore during the period from 2002 to 2013, the relationship between corporate governance and cash holdings is investigated. The results show that characteristics such as board duality and large board size are significantly related to corporate cash policies. The paper provides important evidence that corporate cash serves as a valuable strategic asset, especially during a crisis. This study finds that the relationship between firm performance and cash holding are significantly moderated during tourism crisis. The results show that the stock market places a higher value on corporate cash holdings during the sudden crisis. Finally, the third essay presents a cross-country study using 1274 firm-year observations from 2001 to 2013 from public listed hospitality firms in ASEAN to test the impact of corporate governance on cash holdings. The relationship between external governance mechanism and cash holdings behaviour of firms at country-level are studied. The results show positive and significant relationship between the country-level control of corruption, regulatory quality, the rule of law, and corporate liquidity. However, there is no significant relationship between country-level political stability, voice and accountability and corporate liquidity. Further investigation was carried out to test the effect of tourism crisis and corporate liquidity. The results shall benefit various parties including the legislators and policy makers. Not only it serves as a strategic deterrence, but also helps firms to gauge opportunities
Effects of gender and socioeconomic status towards Form Four Pupils’ statistical thinking abilities / Ong Jing Hui
No full textStatistical thinking abilities of Form Four students are not known as there is a lack of studies that measures it. Despite the fact that the students were exposed to the same curriculum and pedagogy, the thinking abilities of students varied in terms of gender. There is also uncertainty in whether socio-economic status is a cause that affects statistical thinking abilities due to lack of research in that particular area.
This study aimed to examine the effects of gender and socio-economic status on statistical thinking abilities of Form Four students. To answer the three research questions of this study, survey descriptive design and causal comparative design were employed. 180 Form Four students (90 males, 90 females) of three socio-economic status groups mainly low socio-economic status group (N = 65), middle socio-economic status group (N = 98), and high socio-economic status group (N = 17) from several secondary schools in the area of Shah Alam, Selangor participated in this study.
Statistical thinking abilities consist of three levels mainly ability to organize and reduce data, ability to represent data, and ability to analyze and interpret data. An instrument called the Statistical Thinking Abilities Test (STAT) was used to measure Form Four students’ statistical thinking abilities levels. The result of analysis of descriptive statistics showed that most Form Four students were at level 1 (42.2%) and level 2 (46.1%) of statistical thinking abilities levels.
The result from the Mann-Whitney U test revealed that the level of statistical thinking abilities of male students (Mean rank = 95.61) was different with female students (Mean rank = 85.39). The result indicated no significant differences of students’ statistical thinking abilities by gender, U = 3590, p = .148. The result from Kruskal Wallis H test shown significant differences in students’ statistical thinking abilities by socio-economic status, χ2(2) = 34.591, p = .001, with mean rank statistical thinking abilities low socio-economic status (60.07), middle socio-economic status (101.06), and high socio-economic status (145.97).
This study has implication to teachers, researchers, curriculum planners, and teaching educators. Teachers are able to utilize the rubric to gauge the statistical thinking abilities levels of the students and prepare suitable lesson plans accordingly. Researchers can pursue further study by looking at other factors that affect statistical thinking abilities and the interaction effect among them. Curriculum planners benefit from this study through better understanding of the statistical thinking abilities to incorporate them into the mathematics curriculum. Teaching educators also benefit from this study by utilizing the ideas and operations of statistical thinking abilities to monitor students’ development pace of statistical thinking abilities from various socio-economic status backgrounds.
In conclusion, past researches’ findings shown gaps in students’ statistical thinking in comprehending statistical concepts, which prompted the study to measure the statistical thinking abilities levels of Form Four students and the factors that affect it. The findings shown evidence of significant effect of socio-economic status on statistical thinking abilities of Form Four students where most of them are at the first and second level of statistical thinking abilities
Covalent organic framework-supported Zn single atom catalyst for highly efficient N-formylation of amines with CO2 under mild conditions
No full textTransformation of CO2 into value-added chemicals with efficient and recyclable catalyst is an effective way to reduce carbon emissions. It is valuable to develop an efficient catalyst that can promote the N-formylation reaction under mild conditions with a high activity and excellent recyclability. Single atom catalysts (SACs) possess ultimate atom utilization efficiency and outstanding catalytic performance. Herein, we synthesize Zn SACs (Zn-TpPa) anchored on a COF (TpPa-1) using a facile solution method. Catalyzed by Zn-TpPa, CO2 and N-methylamine are transformed into N-methylformanilide under mild reaction conditions with a TOF of 17,155 h−1, which is the highest among all reported recyclable Zn-based catalysts. Zn-TpPa can also catalyze N-formylation of many other amines with excellent yields. The higher reactivity was attributable to the well-dispersed Zn active sites on COF and outstanding adsorption of CO2 owing to high surface area of COF. Our research provides a facile method for constructing SACs as well as an effective pathway for CO2 transformation and environmental protection.
Graphical abstract
Zn Single atom catalysts anchored on COF (TpPa-1) are prepared in a facile method and characterized. Zn-TpPa promotes N-formylation of N-methylaniline with CO2 and phenylsilane under mild conditions with the highest TOF among all reported recyclable Zn-catalysts. Besides, Zn-TpPa can catalyze N-formylation of many other amines with excellent yields. The work provides a facile method for constructing SACs.
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Introduction
Carbon dioxide (CO2), known as the main factor for green-house effect, has stimulated much effort to develop efficient technologies and methods for decreasing the CO2 level in the atmosphere. [[1], [2], [3], [4], [5]] As CO2 is a non-toxic, abundant, renewable C1 building block, easily available and environmentally benign feedstock, in view of green and sustainable chemistry, designing recyclable catalysts for the transformation of CO2 into value-added chemicals has recently emerged as an attractive route. [[6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23]] One interesting route to fix CO2 is synthesis of formamides through N-formylation of amines using CO2 in the presence of reducing agent. Many catalysts were reported to promote this reaction. [10,16,[24], [25], [26], [27], [28], [29], [30]] However, those reported N-formylation catalysis either have a limited turnover frequency (TOF) [21,[31], [32], [33], [34], [35], [36]] or require harsh conditions, such as high reaction temperatures (>60 °C) [7,15,21,25,34,[36], [37], [38]] or high CO2 pressure (>1 Mpa) [6,7,[13], [14], [15],21,32,33,[37], [38], [39], [40]] and poor recyclability [35]. It is highly desirable to develop an efficient catalyst that can promote the N-formylation reaction under mild conditions with a high TOF and excellent recyclability.
Single-atom catalysts (SACs), containing single metal atoms anchored on solid supports, represent the utmost utilization of metallic catalysts and thus maximize catalytic reactivity. [[41], [42], [43], [44], [45]] Several fabrication processes for SACs have been reported [46], including atomic layer deposition, [47] wet chemistry [48], MOF derivative [49], potential cycling [50], acid leaching [51] and photodeposition [52]. However, they usually either require harsh conditions, such as high temperature, high pressure, acids or complicated reaction procedures. Considering the large-scale production in future industrialization, a simple and efficient way to achieve SACs is more favorable. An appropriate support is critical to interact strongly with isolated atoms, and thus prevents the movement and aggregation of isolated atoms [[53], [54], [55]], creating stable, finely dispersed active sites.
Covalent organic frameworks (COFs) represent an important type of covalent porous materials with high surface area and well-defined structures. [56,57] The periodic and permanent porosity endow COFs an excellent substrate for SACs [58]. The bottom-up synthesis using different building blocks endows COFs with tunable skeleton structure, pore size, and topology schemes [53,59,60]. With the bottom-up synthesis of COFs followed by post-metalation, it offers unprecedented opportunities for constructing SACs with well-defined catalytic centers in high metal loading [61].
Herein, we demostrate Zn single atom catalyts can be prepared on COF (TpPa-1) with high loading amount by facile dropwise adding Zn2+ solution into TpPa-1 suspension (Scheme 1) [62,63]. Catalyzed by Zn-TpPa, N-methylformanilide is produced by reacting N-methylaniline with CO2 and hydrosilanes under mild reaction conditions (1 bar CO2 pressure at room temperature) in 3 h with a TOF of 17,155 h−1, which is the highest among reported recyclable Zn-based catalysts. Besides, Zn-TpPa could catalyze N-formylation of many other amines with excellent yields. Our research provides a simple yet efficient method for constructing SACs as well as provides an effective and sustainable pathway for CO2 transformation and environmental protection.
Section snippets
Materials and characterizations
1,3,5-triformylphloroglucinol (Tp) and p-phenylenediamine (Pa-1) were purchased from Shanghai Macklin Biochemical Co. Ltd. N-methylaniline, aniline, p-toluidine, N-methyl-p-toluidine, 4-methoxy-N-methylaniline, 4-bromo-N-methylaniline, N-methylcyclohexylamine, diethylamine, pyrrolidine, morpholine, 1,2,3,4-Tetrahydro-1-methylquinoline, and phenylsilane were obtained from J&K Scientific Ltd. N, N-dimethylformamide, acetonitrile mesitylene, dioxane and methanol were obtained from Aladdin
Characterization of materials
We synthesized single atom catalysts Zn-TpPa by adding the aqueous Zn salt solution into TpPa-1 suspension (Scheme 1), which was synthesized according to the method as previously reported. [62,63] The composition of TpPa-1 and Zn-TpPa was assessed with X-ray photoelectron spectroscopy. The peaks at 1020 eV and 1045 eV in Zn 2p XPS (Fig. S1d) spectrum indicated the presence of Zn element in Zn-TpPa. Besides, the Zn loading in the Zn-TpPa reached 0.5 wt%, as determined by inductively coupled
Conclusion
In conclusion, Zn single atom catalyst on COF with high loading were facially prepared. Zn-TpPa showed excellent catalyst activity, selectivity and recyclability for N-formation under mild condition with CO2 and phenysilane. It showed the highest TOF normalized to single Zn sites as 17,155 h−1 among all reported Zn-based catalysts. Importantly, Zn-TpPa showed the highest TOF among all reported catalysts which promoted N-formylation of N-methylaniline with CO2 and hydrosilanes with good
CRediT authorship contribution statement
Qiang Cao: Investigation, Conceptualization, Writing - original draft. Long-Long Zhang: Data curation. Chang Zhou: Resources. Jing-Hui He: Supervision, Writing - review & editing, Funding acquisition. Antonio Marcomini: Writing - review & editing. Jian-Mei Lu: Resources, Writing - review & editing, Supervision, Funding acquisition.
Declaration of Competing Interest
The authors report no declarations of interest.
Acknowledgements
We gratefully acknowledge the financial support provided by National Natural Science Foundation of China (21978185, 21938006, 21776190), the National Key R&D Program of China (2020YFC1818401, 2017YFC0210906), Basic Research Project of Leading Technology in Jiangsu Province (BK20202012), Suzhou Science and Technology Bureau Project (SYG201935) and the project supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Effect of the fractions and sub-fractions of adlay seed ethanolic extracts on the growth of human cancer cells
No full text近年來研究指出薏苡籽實萃取物具有抗腫瘤的生理活性。本研究探討薏苡籽實不同部位乙醇萃取物之區分層和次區分層對於人類肝癌 (Hep 3B和Hep G2)、乳癌 (MCF7)、胃癌 (AGS)和子宮頸癌 (HeLa)細胞株生長的影響及可能的作用機制。薏苡籽實不同部位之乙醇萃取物包含薏苡殼 (AHE)、薏苡種皮 (ATE)、薏苡麩皮 (ABE)及精白薏仁 (PAE)。並依極性不同，可將薏苡籽實不同部位之乙醇萃取物 (AHE、ATE、ABE和PAE)區分成正己烷層 (He)、乙酸乙酯層 (Ea)、正丁醇 (Bu)和水層 (Wa)。由MTT分析法結果顯示，AHE-Ea和ATE-Ea對於所有癌細胞生長具有顯著的抑制能力且具有濃度效應，因此更進一步經由管柱層析區分出次區分層。結果顯示AHE-Ea-K、AHE-Ea-L、ATE-Ea-E和ATE-Ea-F次區分層經72小時處理後可抑制婦癌細胞株 (MCF7和HeLa)之細胞存活率，IC50值介於13.7-58.2 μg/mL。由細胞週期分析可知AHE-Ea-K、AHE-Ea-L、ATE-Ea-E和ATE-Ea-F會誘導MCF7之細胞週期停滯於G0/G1期。此外，經AHE-Ea-K和AHE-Ea-L處理後HeLa之細胞週期會停滯於S期，而ATE-Ea-E和ATE-Ea-F則是誘導HeLa之細胞週期停滯於G0/G1期。根據流式細胞儀的檢測結果指出AHE-Ea-K、AHE-Ea-L、ATE-Ea-E和ATE-Ea-F會經由活化caspase-3誘導MCF7和HeLa產生細胞凋亡。綜合以上結果，AHE-Ea-K、AHE-Ea-L、ATE-Ea-E和ATE-Ea-F可經誘導MCF7和HeLa細胞凋亡以抑制其生長。A number of recent studies have shown the physiological activity in anti-tumor effects of adlay extracts. The study was to investigate the effect of fractions and sub-fractions of adlay seed ethanolic extract on the human liver (Hep 3B and Hep G2), breast (MCF7), stomach (AGS) and cervical (HeLa) cancer cell lines and their possible mechanisms. The ethanolic extracts from different parts of adlay seed were named as AHE (hull), ATE (testa), ABE (bran) and PAE (polished adlay). Based on the degree of polarity, these ethanolic extracts (AHE, ATE, ABE and PAE) were separated to hexane layer (He), ethyl acetate layer (Ea), 1-butanol layer (Bu) and water layer (Wa). The results of 3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl- tetrazolium bromide (MTT) assay showed that AHE-Ea and ATE-Ea had the significant capacity against growth of all cancer cells and in the dose-dependent manner, so further partitioned into their sub-fractions via column chromatography. The results showed that AHE-Ea-K, AHE-Ea-L, ATE-Ea-E and ATE-Ea-F sub-fractions inhibited the cell viability of gynecological cancer cell lines (MCF7 and HeLa) for 72 hr, and their IC50 values were 13.7-58.2 μg/mL. The results of cell cycle analysis showed that AHE-Ea-K, AHE-Ea-L, ATE-Ea-E and ATE-Ea-F induced MCF7 cell cycle arrest in G0/G1 phase. Furthermore, cell cycle of HeLa arrest in S phase by AHE-Ea-K and AHE-Ea-L, but ATE-Ea-E and ATE-Ea-F induced its cell cycle arrest in G0/G1 phase. According to the results of flow cytometric analysis, it indicated that AHE-Ea-K, AHE-Ea-L, ATE-Ea-E and ATE-Ea-F induced MCF7 and HeLa apoptosis through induction of caspase-3 activity. In conclusion, AHE-Ea-K, AHE-Ea-L, ATE-Ea-E and ATE-Ea-F could be through inducing apoptosis of MCF7 and HeLa cell lines to inhibit their viability.中文摘要 I
英文摘要 II
英文縮寫對照表 III
目錄 IV
圖目錄 VII
表目錄 IX
第一章 前言 1
第二章 文獻整理 3
2.1 癌症 3
2.1.2 肝癌 5
2.1.3 乳癌 6
2.1.4 胃癌 7
2.1.5 子宮頸癌 8
2.2 薏苡抑癌文獻回顧 11
2.2.1 薏苡簡介 11
2.2.2 薏苡抑癌作用 12
2.2.3 薏苡之成分 13
2.3 細胞週期 21
2.3.1 細胞週期的分期 21
2.3.2 細胞週期的調控 22
2.4 細胞凋亡 26
2.4.1 細胞凋亡之定義 26
2.4.2 細胞凋亡的特徵 27
2.4.3 細胞凋亡與細胞壞死之分別 27
2.4.4 細胞凋亡的測試方法 30
2.4.5 Caspase家族與細胞凋亡之相關性 31
第三章 研究目的與實驗設計 33
3.1 研究目的 33
3.2 實驗架構 34
第四章 實驗材料與方法 35
4.1 實驗材料 35
4.2 實驗細胞株 36
4.2.1 人類肝癌細胞株-Hep G2和Hep 3B 36
4.2.2 人類乳癌細胞株-MCF7 36
4.2.3 人類胃癌細胞株-AGS 36
4.2.4 人類子宮頸癌細胞株-HeLa 36
4.3 化學藥品與溶劑 36
4.3.1 化學藥品 36
4.3.2 溶劑 37
4.4 儀器設備 37
4.4.1 細胞培養用儀器 37
4.4.2 樣品分析用儀器 38
4.5 實驗方法 38
4.5.1 細胞培養 38
4.5.2 細胞存活率分析－MTT assay 40
4.5.3 細胞形態觀察 40
4.5.4 細胞週期分析 41
4.5.5 Caspase-3活性之分析 42
4.6 統計分析 43
第五章 結果 44
5.1 薏苡籽實不同部位乙醇萃取物之區分層及次區分層對Hep G2、Hep 3B、MCF7、AGS和HeLa等癌細胞存活率之影響 44
5.2 AHE-Ea-K和L與ATE-Ea-E和F對MCF7和HeLa之細胞週期和細胞凋亡的影響 50
第六章 討論 54
6.1 薏苡籽實不同部位乙醇萃取物之區分層及次區分層對Hep G2、Hep 3B、MCF7、AGS和HeLa等癌細胞存活率之影響 54
6.2 AHE-Ea-K和L與ATE-Ea-E和F對MCF7和HeLa之細胞週期和細胞凋亡的影響 57
第七章 結論 60
參考文獻 97
附錄 10
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