Ultrafast Optical and X-ray Absorption Studies of Solvation Dynamics

Solvation dynamics, the process of solvent reorganization upon electronic excitation of a solute, is central to our understanding chemical reactions in liquid phase. Ultrafast optical studies of solvation dynamics have so far been carried out on polyatomic molecules, which have internal degrees of freedom. This property does not allow the unambiguous extraction dynamics of the solvent shell. Because of their atomic character (i.e. lacking internal degrees of freedom) and of their solvent sensitive absorption bands (the so-called CTTS or charge-transfer-to-solvent bands), atomic halides represent ideal systems for the study of electronic solvation dynamics. Although these systems have received detailed attention in femtosecond optical studies, very little has been learned about the response of the caging solvent, which results from the fact that optical tools do not extract structural movement in a direct fashion. In this thesis, we combined ultrafast laser and structure-sensitive X-ray spectroscopies to probe in real-time the formation and decay of a nascent iodine atom created by photodetachment of a valence electron from the parent iodide anion. Optical pump-probe experiments are used to assess the photoproduct concentrations on time scales ranging from femtoseconds to nanoseconds. We also carried out detailed optical studies employing 1- and multiphoton detachment of the valence 5p electron from iodide, and confirmed an ultrafast thermal heating of the entire sample on a ps time scale. Static L1 and L3-edge X-ray absorption spectra of aqueous iodide have been recorded and analysed in terms of simulations based on classical, quantum mechanical molecular mechanics (QMMM) and density functional theory (DFT) molecular dynamics. QMMM yields the solvent shell structure that best fits the EXAFS spectrum. Picosecond X-ray absorption near edge structure (XANES) spectra were recorded from 50 ps up to several tens of nanoseconds. They were analyzed with respect to the different photoproducts observed on these time scales, delivering for the first time new spectra for the intermediate reaction products, I0 and I-2. By analyzing the transient extended x-ray absorption fine structure (EXAFS) data of the iodine atoms, we derived a dramatic expansion of ∼0.6 Å of the solvent shell with respect to that of iodide. Femtosecond XANES studies reveal an increase in the binding energies of the 5p and 2s, with respect to those at 50 ps. An increase in the 2s →5 p transition probability is consistent with the increase of the ionization energy of 2s electron of iodine atom at 300 fs, as compared to 50 ps. The 2s →5 p transition probability is found to decrease by ∼1.1 times from 300 fs to 50 ps

Adaptation options for agricultural cultivation systems in the South Central Coast under the context of climate change: Assessment Report.

This report highlights the results of consultation meetings and field visits organized by the Department of Crop Production and the CGIAR Research Program on Climate Change, Agriculture and Food Security in Southeast Asia in association with the three offices of the Department of Agriculture and Rural Development in the South Central Coast provinces of Binh Thuan, Ninh Thuan, and Khanh Hoa, in combination with consultation with the provinces in the conference: “Summing up crops production in the Winter-Spring season in 2018-2019, implementing the Summer-Autumn season, Main rice season in 2019 for the South Central Coast and the Central Highlands” held by the Ministry of Agriculture and Rural Development in Tam Ky City, Quang Nam Province on 12 April 2019. The meetings underlined the progress made by the provinces on climate change adaptation and mitigation, options for risk reductions in agricultural production, and conversion of crop structure as results of implementing the guidelines of the provinces and the Sector, especially, solutions for reservation and efficient and economic use of water under the context of climate change. This assessment report also reviews some issues related to the agricultural transformation of the region in adapting to risks caused by climate change. They are based on comparative advantages in terms of geographical location and market of key agricultural products. This report also points out shortcomings in using land and unreasonable points in managing and using important natural resources, especially water, and provides recommendations for the agricultural transformation and inter-regional connection with the Central Highlands and the Southeast. The team also introduces climate-related risks maps and adaptation plans (CS MAP) which is applied in the five provinces in the Mekong Delta Region, and hopes this solution’s expansion shall be supported by the Ministry of Agriculture and Rural Development and the provinces

Knowledge and attitudes about research ethics among social researchers in Vietnam: A cross-sectional study

Social research has attracted significant attention in Vietnam during recent years with more questions and discussions about how to promote the research outputs and publications in this area. However, there is limited information about the knowledge and attitudes of social researchers for research ethics in Vietnam. This paper aims to assess the knowledge and attitudes of social researchers about research ethics in Vietnam. A survey with 1200 questionnaires, through convenience sampling, was sent either printed copies or email to social researchers in the universities and research institutions in Vietnam. Our response rate was 65% (782), with mean age: 35.9 years (sd=.307). The results show that around one fifth had been trained with research ethics (23.5%), which led to significant responses to the "do not know" about the research ethics principles and research ethics committee with 14.3% and 55.3%, respectively. Despite such few experiences on the research ethics, the participants presented a positive understanding of the general principles of research ethics and positive attitudes to the importance of the related general ethics principles to social research in Vietnam. Such understandings and attitudes also led to the readiness to apply the research ethics values and principles while there are no formal ethical guidelines in Vietnam social research. These findings suggest that Vietnamese social researchers understood most critical ethics principles in social research and expect formal ethical guidelines

Study on structure of the Earth’s crust in Thua Thien-Hue province and adjacent areas by using gravity and magnetic data in combination

This paper presents the structural characteristics of the Earth’s crust in Thua Thien-Hue province and adjacent area based on interpretation of gravity and magnetic data in combination. Research results have shown that: The depth of crystalline basement varies complicatedly, in the range of 0–11 km. The depth of Conrad surface increases from Northeast (12 km) to Southwest (18 km) and the depth of Moho surface is 23–34 km; The density of sedimentary layer changes from 2.61 g/cm3 to 2.65 g/cm3. Meanwhile, the density of granitic layer is in the range of 2.68–2.73 g/cm3. The basaltic layer has the density value of 2.88–2.93 g/cm3 and the average density of lower layer of the Earth’s crust is about 3.30 g/cm3; The depth of second-order faults, Red River and A Luoi - Rao Quan, is through the Earth’s crust. Meanwhile, the depth of influence of third-order faults, Chay river, Dong Ha - Phu Vang, Vinh Linh, Hue - Son Tra and Tam Ky - Phuoc Son, is within the thickness of the Earth’s crust

Dry Eyes Status on Des Scale and Related Factors in Outpatients at Vietnam National Institute of Ophthalmology

BACKGROUND: Dry eye (DE) can effect on quality of life by pain, inability to perform certain activities that require prolonged attention (driving, reading,…) and productivity at work and finally effect to Q0L associated with DE. OSDI is scale questionnaire is created team to measure the quality of life related to ocular surface disease. AIM: To describe the dry eye disease according to OSDI scale and related factors of this disease. METHODS: A cross-sectional descriptive study was carried out on outpatients (≥ 16-year-old) who were examined and diagnosed with dry eyes at Vietnam National Institute Of Ophthalmology from April to July 2018. Data was collected using the OSDI questionnaire. RESULTS: The average age of participants was 44.6 years; 80.9% of patients were female; 39.9% were identified having mild dry eye. The related factors have been identified that associated with severe dry eye, including age OR = 1.03 (95%CI: 1.01-1.05, p = 0.005), binocular good vision OR = 0.11 (95%CI: 0.05-0.23; p < 0.0001), medical history OR = 17.09 (95%CI: 2.24-130.25; p < 0.0001), chronic conjunctivitis OR = 0.36 (95%CI: 0.14-0.91; p = 0.027), refractive errors OR = 0.14 (95%CI: 0.04-0.48; p < 0.0001), Sjogren's syndrome OR = 31.13 (95%CI: 7.08-136.76; p < 0.0001). CONCLUSION: Several related factors have been identified associated with severe dry eye, including: age, binocular good vision, medical history, chronic conjunctivitis, refractive errors, Sjogren's syndrome

Control of Vibrio parahaemolyticus (AHPND strain) and improvement of water quality using nanobubble technology

Nanobubble technology is used in wastewater treatment, but its disinfectant properties in aquaculture have not been clearly demonstrated. This study investigated the ability of nanobubbles to reduce Vibrio parahaemolyticus (AHPND strain) and to improve water quality. Two laboratory experiments were conducted over a one‐week period, that is (a) assessing the effects of air and oxygen nanobubbles for 60 minutes per day and (b) comparing effects of ozone nanobubble treatments for 2, 4 and 6 minutes per day. Experiments were done in triplicate 100 L tanks with 15‰ saline water, inoculated with an initial bacterial concentration of 106 CFU/ml. At the end of experiment 1, the bacterial concentration of the air and oxygen nanobubble groups was counted for 69% and 46% of the control group respectively. At the end of experiment 2, the bacterial concentration of the 2‐, 4‐ and 6‐minute ozone nanobubble groups were counted for 23%, 2.2% and 0% of the control group respectively. Oxygen and ozone nanobubbles significantly increased oxygen reduction potential and oxygen values. Results indicate that under effective dosages nanobubbles can be used in the production farms to control V.parahaemolyticus and increase oxygen levels

Some preliminary results of paleo-tsunami study in the coastal region of the Nghe An province, Vietnam

In the coastal region of the Nghe An province, the geomorphology is characterized by appearances of fields of arca granosa with placura placenta and hills of placura placenta with arca granosa, namely: The hills of placura placenta with the arca granosa shells in the Quynh Van and Nghi Tien communes; the fields of arca granosa with the placura placenta: deep-seated in the Quynh Nghia, Dien Chau and along the Nghi Yen coast  which have age of 4,500 - 4,300 yrs.; The appearance of the placura placenta-arca granosa shell’s fields and hills which do not originate from either marine transgression in the Holocene epoch, tectonic movement or artificiality; Our results suggest that there were three tsunami events occurring in the past during the periods of 4,500 - 4,300; 4,100 - 3,900 and 900 - 600 yrs., respectively in the region