Pressurized water reactor loss-of-coolant accidents by hypothetical vessel rupture

Also issued by the 1st author as an Sc. D. thesis, Massachusetts Institute of Technology. Dept. of Nuclear Engineering, 1972Includes bibliographical references (leaves 331-349

Chemical examination of Hydrocotyle bonariensis L. (Apiaceae)

Hydrocotyle bonariensis, growing in the Mekong-delta, is used as vegetable and has not yet been chemically studied. From the aerial parts of H. bonariensis, three compounds had been isolated: a triterpene squalene (1) and a mixture of two lignans: hinokinin (2) and α-[3,4-methylendioxy phenylmethylidene]-β-[3,4-methylendioxyphenylmethyl]-γ-butyrolactone (3). The fresh plant was divided into stem-leaf and flower and each part was distilled with steam to afford essential oils. The major components of stem-leaf are: (Z)-3-hexen-1-ol, trans-caryophyllene, α-farnesene, copaene while the major components of flower are: α-pinene, 2-β-pinene, β-myrcene, limonene, α-caryophyllene, epibicyclosesquiphellandrene. The essential oil of the stem-leaf showed cytotoxic activities in vitro on RD and Hep-G2 cancer cells with the IC50 values of 16.1 and 19.9µg/ml, respectively. The study on the plant is being continued

Preimplantation Genetic Testing of Aneuploidy by Next Generation Sequencing: Association of Maternal Age and Chromosomal Abnormalities of Blastocyst

BACKGROUND: Aneuploidy is a major cause of miscarriages and implantation failure. Preimplantation genetic testing for aneuploidy (PGT-A) by Next Generation Sequencing (NGS) is able to detect of the numeral and structural chromosomal abnormalities of embryos in vitro fertilization (IVF). AIM: This study was aimed to assess the relationship between maternal age and chromosomal abnormalities NGS technology. METHODS: 603 human trophectoderm (TE) biopsied samples were tested by Veriseq kit of Illumina. The relation of marternal age and chromosomal abnormality of blastocyst embryo was evaluated. RESULTS: Among the 603 TE samples, 247 samples (42.73%) presented as chromosomal abnormalities. The abnormalities occurred to almost chromosomes, and the most popular aneuploidy observed is 22. Aneuploidy rate from 0.87% in chromosome 11 to 6.06% in chromosome 22. The rate of abnormal chromosome increased dramatically in group of mother's ages over 37 (54.17%) comparing to group of mother's ages less than 37 (38.05%) (p < 0.000). The Abnormal chromosome and maternal age has a positive correlation with r = 0.4783 (p<0.0001). CONCLUSION: These results showed high rate abnormal chromosome and correlated with advanced maternal age of blastocyst embryos

The Association Between Ambient Temperatures and Hospital Admissions Due to Respiratory Diseases in the Capital City of Vietnam

This study aimed to examine the short-term effects of ambient temperature on hospital admissions due to respiratory diseases among Hanoi residents. We collected 34,653 hospital admissions for 365 days (November 1, 2017, to November 31, 2018) from two hospitals in Hanoi. A quasi-Poisson regression model with time series analysis was used to explore the temperature-health outcome relationship's overall pattern. The non-linear curve indicated the temperatures with the lowest risk range from 22 degrees (Celcius) to 25 degrees (Celcius). On average, cold temperatures showed a higher risk than hot temperatures across all genders and age groups. Hospital admissions risk was highest at 13 degrees (Celcius) (RR = 1.39; 95% CI = 1.26–1.54) for cold effects and at 33 degrees (Celcius) (RR = 1.21, 95% CI = 1.04–1.39) for the hot effects. Temporal pattern analysis showed that the most effect on respiratory diseases occurred at a lag of 0 days for hot effect and at a lag of 1 day for cold effect. The risk of changing temperature among women and people over 5 years old was higher than other groups. Our results suggest that the risk of respiratory admissions was greatest when the temperature was low. Public health prevention programs should be enhanced to improve public awareness about the health risks of temperature changes, especially respiratory diseases risked by low temperatures

Insights On Muscle Myosin Relaxation States And Actin-Based Drug Discovery

University of Minnesota Ph.D. dissertation. 2020. Major: Biochemistry, Molecular Bio, and Biophysics. Advisor: David Thomas. 1 computer file (PDF); 112 pages.Healthy muscle function hinges upon balanced contraction and relaxation cycling of muscle proteins. The main proteins involved are myosin and actin, making them desirable therapeutic targets for modulating muscle dysfunctions. In relaxation, the two heads of myosin have been shown to form an auto-associated state, that is hypothesized to be an auto-inhibited state with extremely slow ATP turnover, termed the super-relaxed state (SRX). Numerous efforts are underway to understand the biophysical properties of the SRX and its physiological roles in skeletal, cardiac, and smooth muscle. SRX is involved in resting skeletal muscle thermogenesis and in cardiac muscle contractility, with profound implications for health issues such as obesity, aging, and heart disease. Part of my thesis research focuses on the relationship of SRX to aging in skeletal muscle, as measured by quantitative epifluorescence microscopy, to fill in the knowledge gap between basic biophysics and muscle physiology. This is the first time that myosin SRX is directly studied through the physiological lens of aging. The long-term goal is to establish the role of SRX in age-related attenuation of muscle function, especially in humans, and to use these insights to design therapeutic approaches. Progress on this topic is presented and discussed in Chapter 2 (correlation of SRX with aging in mouse muscle) and Chapter 3 (the first SRX measurements in human muscle, correlated with fiber type). Some of this work has been published previously1, and that article has been adapted, with permissions, to fit the format of this dissertation. Actin, the main binding partner of myosin, is the focus of Chapter 4. I established biochemical and biophysical assays that can be used to complement the fluorescence resonance energy transfer (FRET)-based technology our lab has pioneered for drug discovery targeting actin. These assays allow us to further identify potential therapeutic compounds that are specific to skeletal or cardiac muscle. Overall, my studies lay the groundwork for applying biophysical techniques, such as optical spectroscopy, to translational science, to elucidate the molecular basis of disease and to set the stage for development of new treatments

Age affects myosin relaxation states in skeletal muscle fibers of female but not male mice

The recent discovery that myosin has two distinct states in relaxed muscle–disordered relaxed (DRX) and super-relaxed (SRX)–provides another factor to consider in our fundamental understanding of the aging mechanism in skeletal muscle, since myosin is thought to be a potential contributor to dynapenia (age-associated loss of muscle strength independent of atrophy). The primary goal of this study was to determine the effects of age on DRX and SRX states and to examine their sex specificity. We have used quantitative fluorescence microscopy of the fluorescent nucleotide analog 2′/3′-O-(N-methylanthraniloyl) ATP (mantATP) to measure single-nucleotide turnover kinetics of myosin in skinned skeletal muscle fibers under relaxing conditions. We examined changes in DRX and SRX in response to the natural aging process by measuring the turnover of mantATP in skinned fibers isolated from psoas muscle of adult young (3–4 months old) and aged (26–28 months old) C57BL/6 female and male mice. Fluorescence decays were fitted to a multi-exponential decay function to determine both the time constants and mole fractions of fast and slow turnover populations, and significance was analyzed by a t-test. We found that in females, both the DRX and SRX lifetimes of myosin ATP turnover at steady state were shorter in aged muscle fibers compared to young muscle fibers (p ≤ 0.033). However, there was no significant difference in relaxation lifetime of either DRX (p = 0.202) or SRX (p = 0.804) between young and aged male mice. No significant effects were measured on the mole fractions (populations) of these states, as a function of sex or age (females, p = 0.100; males, p = 0.929). The effect of age on the order of myosin heads at rest and their ATPase function is sex specific, affecting only females. These findings provide new insight into the molecular factors and mechanisms that contribute to aging muscle dysfunction in a sex-specific manner.peerReviewe

Evaluating the Performance of a Diffusive Gradient in Thin Film Embedded with Montmorillonite for the Determination of Labile Cd, Pb, Mn, and Zn in Natural River Water

Montmorillonite (MMT), a natural clay mineral with high ion-exchange capacity and trace metal adsorbability, has been demonstrated to be a suitable binding phase in the diffusive gradient in thin film (DGT) technique for the determination of labile trace metals in synthetic water samples. However, in situ working performance of DGT-MMT with natural river water has not yet been investigated. The present study examined the performance of a DGT containing montmorillonite (MMT) for the in situ isolation and determination of labile Cd, Pb, Mn, and Zn fractions in Lach Tray River water, North Vietnam. The repeatability and accuracy of the DGT-MMT probe were assessed on the basis of seven measurement replicates performed on Cd2+, Pb2+, Mn2+, and Zn2+ standard solutions. Then, the DGT-MMT probes were deployed in Lach Tray River water at different sampling sites to determine the labile metal fractions present in river water. By comparing the total and dissolved metal concentrations in the river water, the distributions of the four tested trace metals were constructed. The proportions of the dissolved fractions of Cd, Pb, Mn, and Zn were 46.7–73.7%, 38.5–63.9%, 36.4–41.6%, and 49.8–67.7%, respectively. The results also showed that the high accuracy and reproducibility of the DGT-MMT data were comparable with measurements obtained by the commonly used DGT-Chelex-100 method. In comparison with the data obtained from anodic stripping voltammetry (ASV), a traditional technique for the determination of non-in situ speciation of trace metals, labile metal concentrations measured by DGT-MMT were in similar ranges. These findings indicate that naturally available montmorillonite can be used as an alternative binding material in DGT probes for the in situ determination of labile metal concentrations in natural watercourses