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This study synthesized cellulose-g-poly(acrylic acid) with high water absorbency using the cellulose extracted from pineapple leaves. The synthesis experiment used a novel combination of ethylene glycol dimethacrylate (EGDMA) and azobisisobutyronitrile (AIBN) as the cross-linker and the initiator, respectively. Experimental results showed that the concentrations of AIBN and EGDMA had significant effects on the structure and the water absorbency of the cross-linked materials. The cellulose-g-poly(acrylic acid) synthesized with 0.5 wt% AIBN and 0.5 wt% EGDMA had an excellent swelling capacity of 1900 g/g in distilled water, significantly larger than previously reported ones. Compared with poly(acrylic acid), the cross-linked product demonstrated an absorbency improvement of 1.65 times in distilled water and 1.27 times in 8.6 ppm NaCl solution that was the highest salinity level in Ben Tre, Vietnam, in March 2020. Therefore, the obtained product showed high potential for agricultural applications, especially in coastal regions facing a growing thread of saltwater intrusion.

This thesis consists of three key papers, which are presented in chapters 2, 3 and 4. The three chapters examine three different issues in financial risk management and corporate investment. Chapter 2 evaluates the effects of International Monetary Fund (IMF) programs on corporate default risk. Chapter 3 investigates the relationship between internal capital market efficiency and and diversified firm default risk. Chapter 4 studies the role of internal capital market efficiency in predicting the subsequent stock returns of diversified firms. Chapter 3 is the bridge that links the three key chapters in this thesis together. It shares the same scope with chapter 2 in the financial risk management area and with chapter 4 in the corporate investment area. Using firm-level expected default frequency (EDF) metrics from Moody's KMV and an event study style approach, chapter 2 investigates how corporate default risk responds to IMF intervention and whether the magnitude and direction of the effect are different for the financial versus non-financial sector and for various program sizes and types during the period from 1996 to 2012. Our findings suggest that corporate default risk increases consistently before and after IMF announcements, and is mainly driven by the financial sector in the countries receiving Standby Arrangement (SBA). We also find that countries receiving the smallest IMF program sizes experience greater increases in corporate default risk than the ones receiving the largest loan sizes. These results are robust to the control for the issue of endogeneity. Sharing the same scope with chapter 2 in the financial risk management area, chapter 3 seeks to establish the link between corporate investment and corporate default risk by studying the effect of Internal Capital Market Efficiency (ICM) on diversified firm default risk, and how this effect varies in firms with different levels of external financial constraints during the period 1997-2014. Following Billett and Mauer (2003), we define ICM as the movements of funds from the segments with low return on assets to the segments with high return on assets. Using panel data of 11,202 firm-year observations in the US, we find a negative association between diversified firm default risk and their use of internal funds. However, this relationship is only economically significant in highly leveraged firms. Our findings are robust to the three measures of credit risk: Merton-style default probabilities, the Altman Z-score and S&P credit rating. In addition, though the theory suggests that ICM has a stronger effect on the default risk of financially constrained firms, we find weak evidence supporting this argument. Our result shows that ICM only has a larger impact on financially constrained firm default risk in the case of the Altman Z-score. Taking the ICM computed in chapter 3 as a proxy for diversified firms' expected profitability, chapter 4 investigates the role of this measure in predicting stock returns of diversified firms during the period 1997-2015. Our expected profitability proxy is distinguished from other proxies suggested in the literature since our measure takes into account the firm's current level of external financial constraints. We find that ICM can help predict stock returns, and this predictive ability is incremental to the other stock return predictors identified in the literature such as book to market ratio, firm size, default risk, accruals and Piotroski's (2000) F-score. Furthermore, when examining the relationship between ICM and future stock returns separately for financially constrained and non-financially constrained firms, we find that ICM is only important in predicting stock returns in the former group.

This is a preliminary study of a material comprising gelatin (Gel), silver nanoparticles (AgNPs) and curcumin (Cur) aimed for wound-healing treatment. Gelatin was used to stabilize AgNPs and encapsulate curcumin to form a therapeutic composite (GelCurAg) for their strong bactericidal and antioxidant properties. GelCurAg formulations with different gelatin concentrations were characterized to attain information about their physiochemical properties and the loading efficiency of therapeutic agents. In vitro assessment of GelCurAg focused on antibacterial, antioxidant and cytotoxic aspects. The results suggested that Gel1CurAg (synthesized from 1% gelatin solution) could be utilized as potential therapeutic agents in treating infectious wound owing to its bactericidal and antioxidant effects and low toxicity for clinical uses., GRAPHICAL ABSTRACT

This study primordially aimed at determining the effects of different factors affecting employee’s motivation at Groz-Beckert Vietnam Co. Ltd. Upon perusal and review of related literature, the researchers found out that there is a dearth of studies that have been conducted relative to this subject appertaining to MNCs in Asian countries. Thus, this paper intends to provide empirical evidences towards the link between and among selected variables being covered in this study. The researchers used the quantitative research analysis method which have surveyed and floated questionnaires to 300 employees from various units, departments, divisions at Groz-Beckert Vietnam Company Ltd and retrieved 265 validated responses. Research result further revealed that, out of the 7 factors: income and benefit, superior, work result, colleague, work condition, training and promotion, work nature positively and significantly impacts the staffs and workers of the said organization. Based on research results and findings, the researchers will provide some viable and palatable recommendations for the human resource development policies and such proposals can enhance employee’s motivation in the said entity. For ease of data collection, convenience sampling was adopted. Data were analyzed using SPSS version 21 that included descriptive and inferential statistics. The outcomes of the study showed that almost all the variables have positive correlation with the workers motivation in performing their jobs at the workplace.

Titanium (Ti) abutment is a supporting structure of dental implant which anchors and provides retention for fixed or removable tooth restoration. However, bio-inert property of Ti leaves the soft tissue to detach from the abutment, partly leading to implant failure. Meanwhile previous studies have mainly focused on enhancing the osseointegration of Ti implant, the dislocation and imbalance of dental implant still occur since the connective tissue defect at the abutment. This study aimed to investigate the interaction between fibroblast and the modified Ti in which type 1 collagen (Col-1) was modified on Ti surface. Ti/Col-1 modification was performed by electrochemical deposition (ECD) based on the polyelectrolyte property of Col-1 and conductivity of Ti under electric field. Parameters optimized for ECD were investigated including Col-1 concentration, pH of electrolyte, and deposition potential. Fibroblast's cell adhesion/spreading, and cell viability/proliferation assays were analyzed between the coated Ti/Col-1 with optimized ECD conditions and uncoated Ti. Scanning Electron Microscope (SEM) observation indicated that Col-1 was modified successfully on Ti while fibroblast cell adhered and proliferated well in Ti/Col-1 compared with the uncoated Ti. This study suggested the influence of Col-1 modification on the attachment of fibroblast cells around the Ti abutment.

This study was aimed to develop a tissue engineering scaffold by incorporation of Bombyx mori silk fiber (BMSF) and agar. This promised the improvement in enhancing their advantageous properties as well as limiting their defects without occurring chemical reactions or crosslink formation. The morphology and chemical structure of scaffolds were observed using scanning electron microscope (SEM) observation and Fourier transform infrared (FT-IR) spectra. The SEM results show that scaffolds containing BMSF have microporous structures, which are suitable for cell adhesion. Agar scaffolds, by contrast, had much more flat morphology. FT-IR spectra confirm that no modifications to BMSF happened in scaffolds, which indicates that there was no chemical reaction or crosslink formation between silk and agar in this process. Furthermore, the biocompatibility of scaffolds was performed in the mouse’s subcutaneous part of the dorsal region for 15 days, followed by Haematoxylin and Eosin (H&E) staining. H&E staining results demonstrate that scaffolds had good biocompatibility and there was no sign of the body rejection in all of samples. The results from animal study show that SA scaffolds have the most stable structure for cell adhesion compared with those single materials.

In the paper, we propose a navigation method using fuzzy line tracking and D∗Lite algorithm based on a QR code map. Path planning using D∗Lite is implemented on the server. Fuzzy line tracking is developed by using image processing technique. At first, we design a virtual map which is composed of QR code nodes. We generate an optimized path for navigation on the map. Accuracy of the navigation is enhanced by fuzzy line tracking method. The proposed method is verified by simulation study as well as experiment on a real environment.

In this paper, a navigation method using fuzzy line tracking, QR code recognition and path planning algorithm is proposed for the transportation robot. We build a grid map by attaching QR codes on a floor and using lines that are gaps between tiles. The transportation robot is developed with a camera to capture floor images that is used to detect QR code and extract lines’ parameters by applying linear equation and FIR filter. A fuzzy decision-maker is designed to solve the deviation problem occurring during a navigation process between QR codes. The QR code is used to get the current position and recognize the direction to neighbor QR codes. Finally, the D*Lite algorithm is applied to search for an optimal path from the robot position to a goal position on the grid map using QR codes. The proposed method is verified by the navigation experiments of the transportation robot in the real environment. The robot can follow the optimal path obtained from planning algorithm with high stability and accuracy.