ADSORPTION OF MERCURIC ION FROM AQUEOUS SOLUTIONS USING MODIFIED FLY ASH

In this study, fly ash was treated with NaOH solution (FAN) before modifying with (3-mercaptopropyl) triethoxysilane - MPTMS (FAMPS). By using FTIR, FESEM, XRD, EDX, and BET techniques, the change in structure, composition and morphology of FAN and FAMPS was evaluated. The FTIR spectra of FAN and FAMPS showed that there is no chemical reaction between the MPTMS and FAN. After modification, the FAMPS has a rough surface with composition difference from the FAN. Mercuric ion adsorption behavior as well as adsorptionisotherm models (Langmuir and Freundlich) of the FAN and FAMPS were also investigated and discussed. Thanks to FAN modification, the mercuric ion removal percent of the FAMPS was higher than that of the FAN. Owing to the adsorption data, Freundlich isotherm modelwas fitted for the mercuric ion adsorption process

Effects of oil and grape seed tannin extract on intakes, digestibility, milk yield and composition of Saanen goats

An experiment was conducted as a 4×4 Latin square design using 4 lactating Saanen goats, 19 months old and 47.9±1.04 kg of body weight, to evaluate the effect of oil and grape seed tannin extract (GSTE) supplementation on feed intake, digestibility, milk yield and milk composition. Each experimental period lasted for 21 days including 16 days for adjustment and 5 days for sampling. Goats were fed a control diet (Ctrl) consisting of 60% concentrate and 40% fresh Para grass (dry matter, DM, basis) while other 3 treatments were supplementation of 2.5% soybean oil (SO); 2.5% soybean oil + tuna fish oil at 3:2 w:w (SFO); 2.5% soybean oil + tuna fish oil at 3:2 w:w + 0.8% GSTE (OCT). The results showed that oil and GSTE did not affect feed intake, digestibility, milk yield and composition of goats (P > 0.05). However, digestibility of EE was higher (P < 0.05) in SFO and OCT diets (85.4% and 84.7%, respectively) compared with Ctrl (76.2%). Combined data suggested that feeding 2.5% oil blend with or without 0.8% GSTE increased EE digestibility in goats without affecting intake, animal performance and milk composition

Impact of Oxygen on Corrosion and Hydrogen Permeation of Pure iron in the Presence of H2S

International audienceThis paper examines the influence of oxygen traces on corrosion and hydrogen charging of steel in H 2 S containing environment. It is well known that H 2 S is the driving force for many types of steel failures such as hydrogen induced cracking (HIC), sulfide stress cracking (SSC), and stress-oriented hydrogen induced cracking (SOHIC). Since it is a huge concern for oil and gas industries, standard test methods have been developed and published as NACE technical methods (e.g. NACE TM0284 and NACE TM0177). Though it is recognized that oxygen pollution shall be avoided during H 2 S cracking tests, there is still a lack of experimental data to illustrate the potential impacts of a small oxygen pollution. The aim of the present study was to check if oxygen traces can modify corrosion mechanisms and hydrogen charging of steel in H 2 S medium. Experiments consisted in hydrogen permeation measurements through thin pure iron membrane. They were performed at corrosion potential in order to be in realistic environmental conditions. Corrosion rate was also evaluated through weight loss measurements. Analysis of test solutions was performed in order to identify reaction products between H 2 S and O 2

Determinants of electronic word of mouth in the restaurant industry: An evidence from Vietnam

The food and beverage industry in Vietnam has developed dramatically, resulting in a highly competitive market. To win the competition, the restaurant managers not only strive to increase customer satisfaction but also create customers’ positive electronic Word-Of-Mouth (eWOM). This study aims to investigate the relationship between customer satisfaction, customer trust, customer loyalty, and eWOM. The quantitative method was implemented to examine the hypotheses in the research model. Data were collected from Ho Chi Minh City respondents using a convenient sampling method. Self-administrated questionnaires were delivered via the Internet for data collection. After data screening, 299 responses were qualified for analysis. Partial Least Squares Structural Equation Modeling (PLS-SEM) analysis was employed by SmartPLS software version 3.0. The measurement model test showed that one item of customer trust has a factor loading of less than 0.7 as a result, this item was removed from the research model. The structural model evaluation revealed the highly predictive accuracy of the model as all dependent variables have R2 values above 0.5. A bootstrapping test with 5,000 subsamples also showed that customer loyalty significantly influences eWOM, but customer trust does not. Customer satisfaction directly and significantly impacts customer trust and loyalty but has little influence on eWOM. However, the relationship between customer satisfaction and eWOM is significant without the presence of customer loyalty and trust. The indirect effect test also determines the full mediation role of customer loyalty in the relationship between customer satisfaction and eWOM

Corrosion and hydrogen permeation of low alloy steel in H2S-containing environments : the effect of test buffer solution chemistry

International audienceH 2 S-containing (sour) service environments present a considerable risk of hydrogen induced cracking (HIC) and sulfide stress cracking (SSC) to steel line pipe, pressure vessel and tubular components during upstream oil and gas production, through the ability of H 2 S to corrode and promote hydrogen entry into the material bulk via a cathodic reaction process. Materials selection for sour service is made via standard test methods such as NACE TM0284 and NACE TM0177. A commonly used test solution (NACE TM0177 solution A) comprises sodium chloride (5.0%) + acetic acid (0.5%), to work in a range between pH 2.8-4.0. When pH stability is essential over long testing periods, solutions that are buffered by acetic acid with sodium acetate are proposed. NACE TM0177 solution B (5.0% NaCl + 0.4% sodium acetate + 2.5% acetic acid) presents an initial pH of 3.4-3.6, specified not to exceed pH 4.0 over the testing duration. Newer, alternative solutions from the high-strength line pipe (HLP) research committee from the Iron and Steel Institute of Japan (ISIJ) propose higher acetic acid/acetate concentrations for enhanced buffering capacity. This may offer practical testing advantages, although material corrosion rates and hydrogen uptake are possibly affected. In this conference proceeding, we report on the corrosion and hydrogen uptake performance of a sour-grade X65 steel exposed to NACE Solutions A and B, and an HLP solution (at the same pH as NACE B solution, i.e. pH 3.5) under continuous H 2 S purging (0.1 MPa, T = 24°C) over 720 hours. Electrochemical methods measure electrochemical impedance at the entry face of, and hydrogen permeation across, the X65 membrane. Overall, the differences we note are linked to the different weak acid/conjugate base concentration. Keywords Hydrogen permeation, acetic acid, hydrogen sulfide, X65 steel

Burden of diarrheal diseases from biogas wastewater exposure among smallholder farmers in Ha Nam province, Vietnam

Livestock production has developed rapidly in Vietnam in recent years, particularly at the small-scale which account for 65% of the total livestock production. Biogas systems are commonly used to treat livestock waste, however, the health risks from biogas wastewater exposure at smallholder farms are not yet well understood. A quantitative microbial risk assessment approach was applied to estimate the burden of diarrheal diseases from biogas wastewater exposure among 451 smallholder farmers using biogas systems in Ha Nam province. A total of 150 biogas wastewater samples were collected and analysed for E. coli, Giardia, and Cryptosporidium. The study showed that farmers faced diarrheal disease risks due to exposure to biogas wastewater at different exposure scenarios. The calculated annual risk of diarrheal disease by E. coli ranked from 0.15 to 0.21; by Giardia ranked from 0.022 to 0.095; and by Cryptosporidium ranked from 0.006 to 0.015. The estimated diarrheal diseases burden from pathogens in all exposure scenarios largely exceeded the reference level of health outcome target of 10-6DALYs loss per person per year recommended by WHO. The results suggest the importance in reducing concentrations of pathogens in biogas wastewater before use in the fields as a means for mitigating public health impacts

STRESS AND COPING STRATEGIES OF SECONDARY SCHOOL TEACHERS IN TRA CU DISTRICT, TRA VINH PROVINCE, VIETNAM

By using a cross-sectional study, this study aimed to determine the ratio of occupational stress, stress levels and the relationship between stress status and social characteristics of the sample, factors at work, as well as how secondary school teachers respond to stress in Tra Cu District, Tra Vinh Province. The study conducted a survey to investigate 466 teachers currently teaching at 14 secondary schools in Tra Cu District, Tra Vinh Province, from May 2020 to June 2020. Research results showed that the percentage of teachers who suffered mild stress and severe stress was 18.9% and 8.1%, respectively. The signs of stress in teachers correlated with several factors such as job demand, work control and ways of coping at work. When the average score of the assessment “job demand” or “work control” increased by one point, the rate of stress on teachers was reduced by 23% (95% CI: 0.73 – 0.81) and 12% (95% CI: 0.84 – 0.93) respectively. By contrast, the average score of “confrontation” increased by one point  leading to 3.21 times higher (95% CI: 2.61 – 3.96) possibility of causing stress. As well as the average score of "avoidance" increased by one point, the possibility of causing stress in teachers increased 3.03 times (95% CI: 2.45 – 3.74). The findings showed that mental health problems in teachers at secondary schools, in general and in Tra Cu District, Tra Vinh Province in particular, had not received sufficient attention. Therefore, the problems should be taken seriously not only by teachers school administration