Elastic and thermodynamic properties of the major clinker phases of Portland cement: Insights from first principles calculations

Portland based cement is one of the most popular materials used in the civil and construction applications. Reliable computational methods to provide an insight into the underlying mechanics of the major phases of this material are of great interest for cement design. The present work investigated the performance of density functional theory (DFT) calculations using the PBE-D2 method to predict the mechanical, thermodynamic properties of four major phases namely Alite C3S, Belite C2S, tricalcium aluminate C3A and tetracalcium aluminoferrite C4AF. The calculated elastic properties were in a good agreement with available experimental data. In addition, a deeper insight into the electron density of state, spin-polarization, atomic charge, as well as free energy and entropy properties were also presented. Further development is necessary to improve the established DFT models for predicting the mechanical properties of the ferrite phase of Portland clinker.publishedVersio

The impact of financial inclusion on income inequality in transition economies

inancial inclusion is considered as a critical factor that contributes to the reduction of income imbalance. This paper uses a two-stage least squares (2SLS) model and two different financial inclusion index to examine the impact of financial inclusion on income inequality in 22 transition economies over 11 years from 2005 to 2015. The paper finds that there was a negative relationship between the financial inclusion index and the GINI coefficient. The paper also suggests some policy recommendations to reduce income inequality through developing financial inclusion

The Relationship between Online Learning and Student Satisfaction with Training Quality in Private Universities during the COVID-19 Pandemic

This study aims to explore the relationship between the influential factors of online learning and the satisfaction of economics and business majors with the quality of their training in the context of the Covid-19 pandemic. A total of 900 students in private universities completed a questionnaire. The principal findings of this research are that the students are satisfied with their online learning and that learning conferencing software is the most important driving factor leading to the students’ satisfaction when compared with learning conditions and learning devices. Another interesting finding is that the experience of using learning conferencing software results in a slight difference in the students’ perceived level of satisfaction, adding that users with more than two years’ experience are more satisfied with their training quality than users with less than one year’s experience. However, the results also show that students want to switch to offline learning when the pandemic is over. This study should, therefore, be of value to higher education authorities wishing to understand their students’ perceptions of online learning. In addition, results from the study suggest more managerial approaches as well as improve the online teaching quality during the pandemic

Investigating the diversity of resistant starch in Vietnamese rice collection

The rapid increase of obesity and type 2 diabetes has recently posed an enormous burden on the healthcare system worldwide. Resistant starch (RS) in rice can escape digestion by enzymes in the small intestine, making its calories unavailable for cells to use. As a result, RS can be used by diabetes patients to prevent diabetes and for obese individuals who do not want extra energy. In our study, 75 Vietnamese rice accessions originating from diverse ecosystems were chosen as plant materials to investigate the diversity of RS content in this collection. The Megazyme kit was used to measure the amount of RS. The release of quinonimine was measured using a spectrophotometer at 510 nm. The results showed that approximately 70% of Vietnamese rice accessions had RS content ranging from 0.015 to 0.2% while only 4% of samples had RS content ranging from 0.6 to 0.8%. The Indica subgroups had significantly higher RS content than the Japonica subgroup. Higher RS content was found in medium- and short- grain rice rather than in long grain. Finally, rice plants grown in rainfed lowlands (RL) and irrigated ecosystems had higher RS content than those grown under mangrove and upland ecosystems. Our results firstly give information about the diversity of RS in Vietnamese rice and secondly may contribute to the field of nutrition by developing a suitable rice-based diet for patients with diabetes or obesity

Factors Affecting Cooperation in the International Supply Chain of Seafood Enterprises: the Case of Vietnamese

Purpose: The purpose of this research is to analyze and evaluate factors affecting cooperation in the international supply chain of Vietnamese seafood enterprises.   Theoretical framework: Operations in international business context are associated with high risks, so cooperation in supply chain helps to improve management flexibility. On the other hand, acccording to the theory of resource dependency, resource sharing and information sharing strategies can affect the quality and the level of cooperation among supply chain partners.   Design/methodology/approach: To achieve the aim of this study, a literature survey related to supply chain and supply chain cooperation is carried out, and empirical analysis is conducted among 327 partners in seafood industry with the results analyzed using Cronbach’s Alpha analysis, exploratory factor analysis (EFA), and linear regression analysis (RA).   Findings: Research results have confirmed that there are six main factors directly affecting the international supply chain cooperation of Vietnamese seafood enterprises including: (1) Trust; (2) Power; (3) Distance; (4) Government policy; (5) Cooperation strategies and (6) Information sharing.   Research/Practical & Social implication: The encouraging policies and simplified export regulations are to be implemented by the government, VASEP and enterprises so the knowledge about international supply chain cooperation will be promoted with the help of comprehensive future research directions.   Originality/value: This is literally one of the first research works in Vietnam to incorporate the information sharing component into the model of affecting factors for international supply chain cooperation. Regardless of business uncertainties, the study shed new light on supply chain cooperation and promote firms to gain an edge in the global marketplace

Ecological and behavioural risk factors of scrub typhus in central Vietnam: a case‑control study

Background: The risk factors for scrub typhus in Vietnam remain unknown. Scrub typhus caused by Orientia tsutsugamushi often presents as an undifferentiated febrile illness and remains under appreciated due to the limited availability of diagnostic tests. This tropical rickettsial illness is increasingly recognized as an important cause of non-malaria acute undifferentiated fever in Asia. This study aimed to investigate behavioural and ecological related risk factors of scrub typhus to prevent this potentially life-threatening disease in Vietnam. Methods: We conducted a clinical hospital-based active surveillance study, and a retrospective residence-enrolment date-age-matched case-control study in Khanh Hoa province, Vietnam, from August 2018 to March 2020. Clinical examinations, polymerase chain reaction and enzyme-linked immunosorbent assay IgM tests were applied to define cases and controls. All enrolled participants filled out a questionnaire including demographic socio-economic status, personal behaviors/protective equipment, habitat connections, land use, and possible exposure to the vector. Multivariable conditional logistic regression was used to define the scrub typhus associated risk factors. Results: We identified 44 confirmed cases and matched them with 152 controls. Among cases and controls, the largest age group was the 41-50 years old and males accounted for 61.4% and 42.8%, respectively. There were similarities in demographic characteristics between the two groups, with the exception of occupation. Several factors were significantly associated with acquisition of scrub typhus, including sitting/laying directly on household floor [adjusted OR (aOR) = 4.9, 95% CI: 1.6-15.1, P = 0.006], household with poor sanitation/conditions (aOR = 7.9, 95% CI: 1.9-32.9, P = 0.005), workplace environment with risk (aOR = 3.0, 95% CI: 1.2-7.6, P = 0.020), always observing mice around home (aOR = 3.7, 95% CI: 1.4-9.9, P = 0.008), and use of personal protective equipment in the field (aOR = 0.4, 95% CI: 0.1-1.1, P = 0.076). Conclusions: Ecological and household hygiene-related factors were more associated with scrub typhus infection,than individual-level exposure activities in the hyper-endemic area. These findings support local education and allow people to protect themselves from scrub typhus, especially in areas with limitations in diagnostic capacit

Study on synthesis of carboxymethyl cellulose from pineapple leaf waste and its potential applications as a thickener

In this study, cellulose and hemicellulose were successfully extracted from pineapple leaf waste at yields of 58.8 and 16.1% by dried weight, respectively. Carboxymethyl cellulose (CMC) was synthesised from pineapple leaf cellulose by an esterification process using sodium hydroxide (NaOH) and monochloroacetic acid (MCA) with isopropanol as the supporting medium. Preparation of CMC was investigated by varying three free factors, namely, NaOH concentration, MCA dose, and cellulose size. The carboxymethylation process was optimised to produce CMC with differing degrees of substitution (DS). The highest DS of CMC (0.86) was obtained with 15% (w/v) NaOH solution, 0.6 g of MCA/g cellulose, and 50 μm cellulose. The obtained CMC were characterised by FTIR spectroscopy, SEM images and XRD diffractions. Moreover, the thickening performance of obtained CMC was also determined. The influence of the CMC’s molecular weight and degree of substitution on the viscosity of 1% (w/v) aqueous solution was tested. The experimental results suggest that the viscosity of the solution increases with increasing molecular weight and degree of substitution of CMC

Retardation of arsenic transport through a Pleistocene aquifer

Groundwater drawn daily from shallow alluvial sands by millions of wells over large areas of south and southeast Asia exposes an estimated population of over a hundred million people to toxic levels of arsenic. Holocene aquifers are the source of widespread arsenic poisoning across the region. In contrast, Pleistocene sands deposited in this region more than 12,000 years ago mostly do not host groundwater with high levels of arsenic. Pleistocene aquifers are increasingly used as a safe source of drinking water and it is therefore important to understand under what conditions low levels of arsenic can be maintained. Here we reconstruct the initial phase of contamination of a Pleistocene aquifer near Hanoi, Vietnam. We demonstrate that changes in groundwater flow conditions and the redox state of the aquifer sands induced by groundwater pumping caused the lateral intrusion of arsenic contamination more than 120 metres from a Holocene aquifer into a previously uncontaminated Pleistocene aquifer. We also find that arsenic adsorbs onto the aquifer sands and that there is a 16–20-fold retardation in the extent of the contamination relative to the reconstructed lateral movement of groundwater over the same period. Our findings suggest that arsenic contamination of Pleistocene aquifers in south and southeast Asia as a consequence of increasing levels of groundwater pumping may have been delayed by the retardation of arsenic transport