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Applications of Ambient Ionization Mass Spectrometry to Detect Phthalates on the Skin and Monitor the Ongoing State of Biochemical Reactions.
No full textAmbient ionization mass spectrometry has improved the understanding of samples for biological and environmental studies. This technique utilizes specialized ionization sources to generate ions from the sample under ambient conditions. This thesis presents potential Thermal Desorption Electrospray Ionization Mass Spectrometry (TD-ESI/MS) applications to detect phthalates on the skin and monitor the ongoing state of biochemical reactions. It consists of three sections: i) association between dermal phthalate exposure and phthalate pollution in Taiwan; ii) monitoring the release of bioactive compound from Pleurotus ostreatus for the Study of the Ergothioneine pathway; and iii) monitoring the formation of Alkylpyrazines from L-Serine and L-Threonine.
The most obvious advantage of this approach is its simplicity and quickness, with the whole procedure taking only a few minutes. Multiple probes assist with dealing with sample collection delays and handling large sample amounts. After collecting the sample, the probes can be assembled rapidly and simply connected to the probe holder. The probes are then delivered to the TD-ESI source for analysis. Thermal adsorption is used in this technique to heat the analytes with thermally stable chemical compounds and volatile molecules. The simplicity of these steps contributes to the strengths of this method, which include being easy, rapid, non-invasive, requiring no sample preparation, and having high throughput.
TD-ESI/MS has become a powerful detection tool for quantifying small molecules in various samples. Its ability to analyze multiple chemical compounds in a single analysis made it an attractive method for researchers in different fields. Therefore, this study shows the potential of TD-ESI/MS in biological and environmental factor studies by using insight-target analyte samples that affect biological and environmental systems.
Environmental pollution is a significant concern worldwide, impacting human health. Traditional methods have limitations, making it crucial to find more efficient and reliable analytical techniques. This study aimed to substantiate the effectiveness of TD-ESI/MS for analyzing environmental pollution using human skin samples. Thai and Taiwanese volunteers were exposed to four phthalates, which can lead to contamination indoors and outdoors. The results showed a significant positive relationship between phthalate intensity and nationality, emphasizing the promising capabilities of TD-ESI/MS as an efficient and reliable analytical technique.
Mushrooms, known for their rapid growth and short life cycle, are fascinating subjects of study. Under favorable conditions, they can grow rapidly, but in unfavorable conditions, they may become damaged or unable to continue. This study utilized TD-ESI/MS to examine the ergothioneine pathway in oyster mushrooms, focusing on its impact on the release of bioactive compounds. Ergothioneine, a natural antioxidant, responds to cellular oxidative stress, acting as a natural protective mechanism for oyster mushrooms against environmental stress factors. The study utilized a probe to collect samples without pretreatment, enabling sensitive, and real-time monitoring of ergothioneine release in Pleurotus ostreatus.
By monitoring the reaction, the study delves into the formation of alkylpyrazines and the identification of side products that emerge alongside the primary reaction pathway. The investigation aims to uncover the potential of ambient mass spectrometry (TD-ESI/MS) for detecting and characterizing alkylpyrazines and their side products. This work illustrates the technique's capability in identifying and characterizing various intermediates as well as rapid decay processes.
This study highlights the substantial benefits of utilizing TD-ESI/MS as a valuable tool for conducting factor evaluation studies and environmental monitoring. The findings from this research significantly contribute to our understanding of phthalate pollution, the response of mushrooms to oxidative stress, and the dynamics of chemical reactions. These insights have important implications for environmental monitoring, human health, biochemical reactions, and the advancement of innovative analytical techniques. Furthermore, this study demonstrates that TD-ESI/MS facilitates high-throughput analysis, making it user-friendly and easy to operate as a potential analytical technique
A Study of Indian Teachers' Burnout: Relationship with Interpersonal Self-Efficacy and Work Experience
No full textThe purpose of this study is to investigate the relationship between teachers' interpersonal self-efficacy, work experience, and burnout among educators in India. A survey was conducted, gathering data from 168 practicing teachers across various educational institutions in the country. The established scales used for data collection were Teachers' Interpersonal Self-Efficacy and Teachers' Burnout. Multiple regression analysis was employed to determine the relationship between the variables. The results revealed a significant predictive model for teachers' burnout based on their interpersonal self-efficacy and work experience. Specifically, teachers' interpersonal self-efficacy (\uce\ub2 = -.661, p < .001) and work experience (\uce\ub2 = -.182, p < .05) were found to have a significant negative impact on burnout. These findings emphasize the significance of enhancing teachers' interpersonal self-efficacy and teaching experience in reducing burnout levels. The implications of this study emphasize the necessity of providing support to teachers in developing and maintaining high levels of interpersonal self-efficacy, implementing stress management strategies, and recognizing the significance of mental health in the workplace to prevent burnout
Seasonal variations in phenology and seed bank of Halophila ovalis in the waters of Dongsha Island.
No full textPhenology, the cyclic biological events in relation to environmental factors, provides insights into the organisms\ue2 role and function in the ecosystem. The seed bank, referring to dormant seeds in sediment, plays a crucial role in assessing population resilience. The seasonal variations in the phenology of seagrass may have a great influence on the dynamic of the seedbank. Halophila ovalis, a pioneer species in seagrass ecosystems, heavily relies on persistent seed banks for population maintenance. The unique environmental characteristics of the lagoon on Dongsha Island, with its semi-enclosed water and significant differences from the coastal environment, may lead to variations among populations. However, the spatiotemporal variation in phenology and seed bank of H. ovalis at Dongsha Island is not yet been studied. Thus, this study aims to explore the influence of the environment of the lagoon on Dongsha Island on the phenology and spatiotemporal dynamics of the seed bank of H. ovalis populations.
The data were collected for five seasons at three sampling sites: the southern coast (SC), the lagoon interior (L), and the lagoon mouth (LM) using the transect method from November 2020 to March 2022. Phenological events (leafing, flowering, fruiting) and seed bank density were quantified for each season, and environmental factors (salinity, temperature) were recorded. Statistical analysis, including Kruskal-Wallis test, correlation analysis, and Principal Component Analysis by R software. We found significant differences in environmental factors among the sampling sites, with the southern coast (SC) exhibiting relatively stable seawater temperature and salinity variations. Phenological traits showed significant differences among the sampling sites, with low population abundance observed during the summer and autumn seasons at the southern coast (SC), while the other sites exhibited the opposite trend. The seed bank density also displayed significantly different patterns among the sites, with the highest seed density observed during winter (12.8 seeds/m2) at the southern coast, summer (11.2 seeds/m2) in the lagoon interior, and spring/summer (1.6 seeds/m2) at the lagoon mouth. The result suggests that the lagoon on Dongsha Island and the coastal environment exhibit significant spatiotemporal differences in environmental factors (water temperature and salinity), which drove in the phenological trends and seed bank dynamics of H. ovalis populations. Flowering periods were observed throughout the year on Dongsha Island, with the main flowering and fruiting period occurring in autumn and winter. Seed bank exhibited not only seasonal but also geographic variations in the coastal area of Dongsha Island
The Mechanistic Study of Organic Photocatalyst Reaction Using Time-Resolved Spectroscopy
No full textThe mechanism study is essential in understanding chemical reactions. Knowing how a molecule transforms from the reactant to the product would help us improve the reaction efficiency by modifying the crucial parameters instead of trial and error. The critical point of the mechanism study is to catch the short-lived intermediates in the reaction process. Recently, studies of photocatalytic chemical reactions have been an active field for their vital applications in organic synthesis and green chemistry. To study underlying reaction mechanisms and intermediates of a visible-light-driven photocatalytic organic synthesis, we have constructed an in situ time-resolved (transient) absorption spectrometer. This setup can perform transient (hundred nanoseconds to a few milliseconds) or long-term (over minutes) time-resolved UV-vis absorption spectroscopy measurements according to experimental demands. The candidate systems of the photocatalytic organic synthesis in this thesis are 1,1-diphenyl-3-(5-(trimethylsilyl)furan-2-yl) propan-1-ol, trimethyl(5-methylfuran-2-yl)silane, and (5-decylfuran-2-yl) trimethyl silane reacting with 1O2 generated by photocatalyst through energy transfer.
Additionally, we have used NMR (nuclear magnetic resonance), steady-state absorption spectra of IR (infrared) and UV-vis (ultraviolet-visible) to measure the NMR chemical shifts of starting materials and products and the associated absorption bands of starting materials, photocatalysts, and products, respectively.
Furthermore, to connect studies of the photocatalytic synthesis experiments in the organic chemistry lab, we have constructed a photocatalytic reactor with green LEDs to conduct the same reactions. Subsequently, the resulting sample solutions at different reaction times were examined using NMR and steady-state absorption spectra to capture the evidence of reaction intermediates. In the analysis of UV-vis spectra, we obtained the consuming time of the reactants in the photocatalytic reaction. Besides, with the help of Prof. Wu (Department of Applied Chemistry, National Chiayi University), the steady-state UV-vis absorption spectra of the starting materials, products, and intermediates speculated in the reaction mechanism were calculated and compared with the experimental results. The UV-vis spectral results from the current experiments show similar spectrum features with the calculated spectrum bands of the suspected intermediates. Different spectroscopic methods and more in-depth reaction kinetics studies will be carried out in the future. However, we cannot accurately measure the wavelength range of 200-230 nm for the in situ transient absorption measurements due to the wavelength limit of the probe light source of the home-built setup. A deuterium lamp will be added to improve the spectrum resolution in the 200-250 nm wavelength range. Lastly, we conducted two well-known photocatalytic reactions, sodium persulfate and tris (bipyridyl) ruthenium) chloride hexahydrate, to compare the performance of our home-built transient absorption setup with the commercial one (Edinburgh Instrument LP980). The acquired time information from our setup is similar to the results from the commercial setup. However, some oscillating noises superimposed on the time traces need to be suppressed. In the future, we will construct a time-resolved infrared spectroscopy setup and a femtosecond-to-nanosecond transient UV-vis absorption spectroscopy system to study the mechanism of various photocatalytic reactions
Structural change of brain associated with sarcopenia by using voxel-based and surface-based morphometry
No full textSarcopenia is an age-related disease and characterized by the progressive loss of muscle mass and muscle function, which usually leads to adverse health problems or inconvenient daily life, such as falls, disabilities, increased disease incidence, and mortality. Previous studies shown that cognitive impairment is quite common among individuals with sarcopenia, but the sarcopenia-related abnormalities of brain structure is rarely seen. Moreover, volumetric measurement or feature evaluation of a relatively large region has been usually performed in previous publications, limiting it to a large-scale observation of brain structure. Therefore, voxel-based and surface-based morphometry is applied in this study to measure the gray matter volume and cortical thickness on a voxel-wise basis. Covariates of brain structure, such as cognitive function, age, and sex, have been adjusted to investigate the structural change of brain associated with sarcopenia.
3D T1-weighted MRI of 301 elderly participants aged over 63 has been collected at 3 Tesla. Each participant was also requested to measure muscle mass, gait speed, and handgrip strength. Among all participants, 210 have been diagnosed with mild cognitive impairment (MCI). After data exclusion due to imaging artifacts, a total of 203 MCI participants were included in the analysis. Based on the diagnostic criteria for sarcopenia established by the Asian Working Group for Sarcopenia in 2019, the participants were divided into the sarcopenia group (n=119) and the control group (n=83). This study also divided the participants into two groups based on gait speed, handgrip strength, and muscle mass, respectively, for group comparison. Furthermore, the linear relationship between gray matter volume and three quantitative measurements, including gait speed, handgrip strength, and muscle mass, has been evaluated.
Results show that no significant difference in gray matter volume and cortical thickness on MCI subjects when either of sarcopenia, low gait speed, low handgrip strength, and low muscle mass groups was compared with the corresponding controls. Also, no linear relationship between gray matter volume and either of gait speed, handgrip strength, or muscle mass has been observed
Measurements of absorption cross sections of the \u1d4973 band of the simplest Criegee intermediate (CH2OO) and the kinetics of the CH2OO reaction with H2O2 by integrated cavity output spectroscopy
No full textThe ozonolysis of unsaturated hydrocarbons is considered to be an important pathway for secondary organic aerosol (SOA) formation. However, the mechanism of SOA formation via Criegee chemistry is still poorly understood. In the atmosphere, H2O2 is an important source of OH radicals and an oxidant for SO2 to form H2SO4. Therefore, the reaction of CH2OO + H2O2 has a significant impact on the formation of SOA and OH radicals in the atmosphere. In addition, the reaction between H2O2 and OH radicals has a considerable influence on the HOx-related atmospheric chemistry. Therefore, knowing the reaction rate of CH2OO + H2O2 may contribute significantly to the subsequent HOx-related research. However, so far the reaction rate of CH2OO + H2O2 has only been theoretically calculated, so this thesis mainly explores the infrared spectrum of CH2OO and its reaction kinetics with H2O2.
We used home-built off-axis integrated cavity output spectroscopy (OA-ICOS) to detect the simplest Criegee intermediate CH2OO. Two mirrors with high reflectivity (R\ue299.99%) form a resonant cavity. When the laser enters the cavity, it will reflect several times in the cavity, which can greatly extend the absorption path length and improve the sensitivity of the system. In the experiment, we will measure the absorption cross section of CH2OO molecule at 1434.5cm\ue21 in \u1d4973 vibration mode, which is ("1.9" 7\uc2\ub1 0.17) \uc3 10\ue220 cm2 molecule\ue21 and calculate the lowest detection limit of this system, which is 1.14\uc3 1011 molecule cm\ue23 molecule cm\ue23.
There are also studies that indicate that in places where large of biomass burned, the concentration of H2O2 in that area will be higher than other areas. And usually this air pollution is more serious in places where Criegee intermediates are also produced, so it is necessary to understand the reaction kinetics of CH2OO + H2O2. We measure the reaction rate of CH2OO+H2O2 and fit the experimental data with simulated data to obtain the reaction rate of this reaction, which is (1.10\uc2\ub10.05)\uc310\ue213 cm3 molecule\ue21 s\ue21
Automatic APT Attack Reconstruction Supporting Lateral Movement
No full textAn Advanced Persistent Threat (APT) attack involves the use of sophisticated techniques and methods to infiltrate target systems over an extended period. The objective is to steal sensitive information, disrupt system operations, or engage in other malicious activities. However, due to the sensitive nature of APT attacks that often involve confidential information, there are limited publicly available real-world APT attack datasets. This limitation hampers the ability of cybersecurity experts to conduct research and develop effective defense measures. To address this issue, an increasing number of researchers are utilizing techniques such as simulation and machine learning to generate artificial APT attack datasets. These datasets can assist cybersecurity professionals in training and evaluating the capabilities of defense systems, enhancing the ability to detect and defend against APT attacks. However, these artificial datasets often lack completeness and have limited scalability in their simulation. Furthermore, the construction process of these datasets is not well-documented in the research, preventing other researchers from reproducing the datasets and limiting the scope of related studies.
This work propose a framework for generating datasets that allows users to adjust the APT attack techniques within it. The framework utilizes the MITRE ATT&CK framework to label the attack traffic based on the Tactics, Techniques, and Procedures (TTP), facilitating researchers in utilizing the datasets for model training. Meanwhile, this work utilizes the framework to reconstruct the APT29 attack process and collect a dataset to validate the feasibility of the framework
Neuregulin-1 (NRG1) modulates cell viability and autophagy of esophageal squamous cell carcinoma
No full textHigh expression of NRG1 has been found in many different types of cancer. But, the mechanism of NRG1 in esophageal squamous cell carcinoma (ESCC) is still unknown. In order to understand the role of NRG1 in ESCC, we used siRNA to silence the expression of NRG1 in ESCC cells, including CE48T, CE81T and CE146T cells. We discussed whether silencing NRG1 with siNRG1 affected growth, death and autophagic activity of ESCC cells. In our study, siNRG1 diminished the expression of NRG1 mRNA and protein, and further reduced its downstream signaling factors, including p-AKT and p-RAF. Moreover, siNRG1 transfection inhibited the cell growth, colony formation, migration and increased dead cell population of tumorsphere in three different ESCC cell lines. Knockdown of NRG1 slightly increased subG1 phase without altering proportion of each phase in cell cycle, suggesting silencing NRG1 induces cell death of ECSS cells. In addition, ablation of NRG1-induced cell death were partially reversed by ROS scavenger (N-Acetyl-L-cysteine or MitoTEMPO) and inhibitors of death factors (Ferrostatin-1, GSK872, Necrostatin-1 or Z-VAD-FMK) in ESCC cells, suggesting various types of cell death were involved in silencing NRG1-induced death. Besides, AKT may negatively regulate autophagy activity through mTOR activation. We also noticed that knockdown of NRG1 decreased protein levels of p62 and induced LC3B-II turnover. Silencing NRG1 also increased autophagosome formation, autolysosome activity and fusion with active mitochondria. Treatment of autophagy inhibitor CQ synergized cytotoxic effects of siNRG1 in ESCC cells, suggesting that autophagy/mitophagy was induced and served as a cytoprotective role in NRG1-silenced ESCC cells. Taken together, NRG1 may modulate survival signaling to diminish autophagy of ESCC, while targeting NRG1 may induce cytoprotective autophagy/mitophagy. Thus, NRG1 may be a novel biomarker and potential therapeutic target for ESCC, and the combination of siNRG1and CQ would be a potential treatment of ESCC
Optimizing Voltage Control for Distribution Networks with Distributed Energy Resources
No full textThis thesis aims to assess the effectiveness of voltage control measures in maintaining acceptable voltage quality in low-voltage distribution networks while considering economic factors and the integration of renewable energy resources. The objectives are to optimize distributed energy resources (DERs) utilization by developing strategies that balance renewable energy integration and voltage management, encourage active voltage regulation by zonal prosumers through coordinated operations, and evaluate the financial benefits and profitability for zonal prosumers through voltage regulation.
This research analyzes different control approaches for distributed voltage regulation services in low-voltage distribution networks. The proposed approach utilizes local energy resources to regulate voltage while optimizing economic retribution for the DERs involved in solving voltage violations within a defined timeframe. Schedulable DERs generation, capacity, and load consumption in a low-voltage distribution network are utilized to validate the effectiveness of the proposed mechanism. The flexibility in harnessing the capacity of renewable assets in the grid and the potential of leveraging renewable energy resources to manage voltage within acceptable limits are emphasized.
The presented test cases simulation results provide evidence for the efficacy of the proposed approach in increasing PV generation utilization, providing voltage regulation, and attaining economic viability
Analysis of environmental DNA horizontal distribution in the unsheltered coastal waters using metabarcoding and ocean color satellite image
No full textMetabarcoding of environmental DNA (eDNA) has emerged as a promising tool for monitoring communities and estimating biodiversity. However, its application in the unsheltered coastal waters has received limited attention, mainly due to the complex nature of water movement. Previous studies have predominantly focused on freshwater systems, which are relatively isolated from contaminations from other water bodies. On the contrary, this study aimed to assess the capability and reliability of eDNA survey in the unsheltered coastal waters. However, it is difficult to track the origin and destination of water mass in the unsheltered coastal waters. Therefore, this study inferred the Gaoping River plume as a potential source of eDNA shed by freshwater and brackish water fishes and as the alternative of water mass in the surface ocean since previous studies showed that the Gaoping river plume could potentially disperse as far as the vicinity of the Xiaoliuqiu Island. If the eDNA signals of freshwater and brackish water fishes can be detected far from the Gaoping River mouth, it indicates that the distribution of eDNA in unsheltered coastal waters is influenced by water mass, leading to the transportation of these signals to areas where they are not typically distributed. Therefore, this hypothesizes that eDNA cannot properly reflect the fish community structure in the unsheltered coastal waters. To investigate this hypothesis, a total of 135 water samples were collected along three radial transects extending 10,500 m from the Gaoping River mouth. The eDNA metabarcoding analysis revealed presence of 178 species from 135 genera, belonging to 75 families. The eDNA signal of freshwater and brackish water fish was detected at distances of up to 8,500 m, 6,500 m, and 10,500 m from the river mouth in transects A, B, and C, respectively. Interestingly, ocean color satellite image corroborated these results by displaying a similar pattern between the Gaoping River plume and the eDNA survey. Principal coordinate analysis (PCoA) further indicated a significant effect of the river plume on the eDNA signal. Collectively, the results from the eDNA survey suggest that the Gaoping River plume can indeed influence eDNA signal distribution. Consequently, the findings emphasize that eDNA can be influenced by the movement of water mass and is not a suitable tool for properly reflecting spatial and temporal fish community structure in the unsheltered coastal waters