EFFECT OF ANION GROUPS ON CORROSION INHIBITION BEHAVIOURS OF VIETNAM ORANGE PEEL ESSENTIAL OIL FOR MILD STEEL IN THE ACIDIC MEDIA

This paper deals with the effect of anion groups (SO42- and Cl-) on inhibition behaviours of Vietnam orange peel essential oil (OPE) for corrosion process of mild steel in acidic media. The electrochemical techniques (potentiodynamic, electrochemical impedance spectroscopy (EIS)), weight loss and scanning electron microscopy (SEM) analyses are used in this study. The results show that anion groups do not affect the inhibition mechanism of OPE. The OPE ­behaves as mixed inhibitor for mild steel corrosion in both 1N HCl and H2SO4 acid. The inhibition efficiency of OPE in 1N HCl is greater than that in 1N H2SO4 which implies that the adsorption of the inhibitor is influenced by the nature of anions in acidic solutions. Moreover, the OPE inhibits both general and pitting corrosion for mild steel in the acidic media.

JAPANESE COINS AND BANKNOTES RECOGNITION FOR VISUALLY IMPAIRED PEOPLE

Recent deep learning techniques are successfully integrated into devices to assist visually impaired people in their daily lives, particularly detecting coins/banknotes. Previous works have focused on well captured devices and examined high-quality images. In this work, we design a framework to recognize Japanese Coin/Banknote (JCB) for low-quality images under various criteria. Discriminate features usually disappear in low-quality images. Consequently, using the depth image in addition to RGB image in processing can be enhanced the accuracy of our system. In this work, we first leverage depth information by using a Monocular Depth Prediction network. Additionally, a pre-trained Deep Convolutional Neural Network process RGB and Depth images, respectively. At last, we combine two networks by an ensemble method to produce more accurate detections. By processing depth images in addition to RGB images, the detection results are thus accurate. As a result, our work achieves 74.1% mean Average Precision (mAP)

Factor substitution in rice production function: the case of Vietnam

Vietnamese rice production has achieved remarkable success over the last couple of decades. This is due to land and market reforms, known as ‘Doi Moi’. There were noticeable changes in policies, such as land and production systems, which were transformed from a collective to an individual contract system in the 1980s. Vietnam made progress in rice production through the legalisation of the privatisation of farm properties and a huge investment in irrigation systems. The country not only ensured its domestic demand, but also started exporting rice and gradually became the second largest exporter in the world. An estimate of the Constant Elasticity of Substitution function (CES) for Vietnam’s rice production is essential for the government to design effective policy on agricultural production. This study makes the first attempt to estimate the nested CES model for Vietnamese rice production in 2012. The paper finds that the elasticity of substitution of Vietnam’s nested CES model lies between 0.44 and 0.46. The results indicate the weak substitutability between land and the capital-labour composite in the nested CES model. This also suggests that it is impossible to take labour as the substitutable factor for land and capital

Two decades of studies on learning management system in higher education: A bibliometric analysis with Scopus database 2000-2020

Over the past twenty years, using learning management systems in higher education has attracted increasing interest from researchers around the globe. In this context, the current study aimed to explore the volume, growth trajectory, and geographic distribution of learning management systems in higher education literature, along with identifying impactful authors, sources, and publications, and highlight emerging research issues. The authors conducted bibliometric analysis on 1334 documents, related to the use of learning management systems in the context of higher education, extracted from Scopus database. The findings show a rapidly growing knowledge base on learning management systems in higher education, especially intensely in the years 2015-2020 and primarily from research in developed societies. This flourishing is consistent with the development trend of international education and the strong development of technology. In addition, the core literature was identified based on the volume of publications and citations. The results also reveal the emerging intellectual structure of the field and provide points of reference for scholars studying the discipline. This paper offers a knowledge map for future research assessments of learning management systems in higher education

FTIR Combined with Chemometrics for Fast Simultaneous Determination of Penicillin and Cephalexin in Pharmaceutical Tablets

In this research, the potential of combining chemometrics with FTIR techniques to provide a rapid and simultaneous quantitative analyses method for determination penicillin, cephalexin is studied. Unlike other methods, FTIR is considered as a time saving method due to its non-destructive and simple sample preparation. Due to the similarity of infrared spectral, PLS and PCR couples with spectral treatment techniques are applied to make the calibration model for penicillin and cephalexin determination at the same time. The result is also validated in term of RMSEP and R2 value using validation set. The FTIR combined with PLS method shows the best results

TÀI NGUYÊN VỊ THẾ CỤM ĐẢO THỔ CHU, PHÍA NAM VIỆT NAM

Located near center of the Gulf of Thailand, the Tho Chu island group is approximately far 160 km from Ca Mau southwestwards, and 100 km from Phu Quoc island northwestwards. This group consists of 8 islands, of which the largest Tho Chu island is of 12.15 km2 wide and 167 m high, and composes of clastic sedimentary rocks. Despite the greatest distance from the coast, this coastal island group has the characteristics of geological structure, morphology, spatial structure, area, height, ecological landscape, dynamics and stability of natural processes that create the great value of geo-natural position resources and favorable residential environment. Regarding value of geo-economic position resources, the island group belongs to Phu Quoc district, but it meets the good conditions to become a district-level administrative unit belonging to Kien Giang province. This is a priority site for sea-island economic development, the island group has a great potential to develop the marine economic sectors such as fisheries, natural conservation, tourism and other important services such as oil and gas extraction, navigation and search-rescue at sea. In terms of value of geo-political position resources, this island group includes Hon Nhan islet as the basic point of A1, so has the great value for Vietnam’s sovereignty, sovereign rights and interests in the Gulf of Thailand. Situating in the politically high sensitive region, the island group possesses the high value on the defense, could develop into a firmly military outpost contributing to national defense and security at sea.Nằm ở gần trung tâm vịnh Thái Lan, cụm đảo Thổ Chu cách mũi Cà Mau khoảng 160 km về phía tây nam, cách đảo Phú Quốc khoảng 100 km về phía tây bắc. Cụm đảo gồm 8 hòn, lớn nhất là đảo Thổ Chu rộng 12,15 km2, cao 167 m, cấu tạo từ đá trầm tích vụn thô. Mặc dù là cụm đảo ven bờ xa bờ nhất của Việt Nam ở vịnh Thái Lan, nhưng các đặc điểm về cấu tạo địa chất, hình thể và cấu trúc không gian, diện tích, độ cao và cảnh quan sinh thái; động lực và tính ổn định của các quá trình tự nhiên,… đã tạo ra giá trị lớn về tài nguyên địa-tự nhiên và môi trường sinh cư thuận lợi cho cụm đảo. Về giá trị tài nguyên vị thế địa-kinh tế, cụm đảo thuộc huyện Phú Quốc, nhưng hội tụ đủ các điều kiện trở thành đơn vị hành chính cấp huyện, thuộc tỉnh Kiên Giang. Đây là vị trí ưu tiên đối với phát triển kinh tế biển-đảo của đất nước, là địa bàn tiềm năng lớn phát triển các lĩnh vực kinh tế biển như thủy sản, bảo tồn thiên nhiên, du lịch và các dịch vụ quan trọng khác như khai thác dầu khí, hàng hải và tìm kiến-cứu nạn trên biển. Về giá trị tài nguyên vị thế địa-chính trị, cụm đảo có Hòn Nhạn là điểm cơ sở A1 có giá trị vô cùng to lớn về chủ quyền, quyền chủ quyền và lợi ích quốc gia trên vịnh Thái Lan. Nằm trong vùng địa-chính trị nhạy cảm cao, cụm đảo có giá trị lớn về phòng thủ, có thể phát triển thành một cụm cứ điểm quân sự vững chắc, góp phần bảo vệ Tổ quốc và đảm bảo an ninh trên biển

The responsibility of C-terminal domain in the thermolabile haemolysin activity of Vibrio parahaemolyticus and inhibition treatments by Phellinus sp. extracts

The thermolabile haemolysin (tlh) of Vibrio parahaemolyticus (Vptlh) from V. parahaemolyticus is a multiple-function enzyme, initially describes as a haemolytic factor activated by lecithin and phospholipase A2 enzymatic activity (Shinoda, 1991; Vazquez-Morado, 2021; Yanagase et al., 1970). Until now, the tlh structure has hypothesized including N-terminal and C-terminal domain, but what domain of the Vptlh structure does the haemolytic activity has not been refined yet. In this study, a 450-bp VpTLH nucleotide sequence of the entire Vptlh gene encoded the C-terminal domain cloned firstly to examine its responsibility in the activity of the Vptlh. The C-terminal domain fused with a 6-His-tag named the His-tag-VpC-terminal domain was expressed successfully in soluble form in the BL21 (DE3) PlysS cell. Remarkably, both expression and purification results confirmed a high agreement in the molecular weight of the His-tag-VpC-terminal domain was 47 kDa. This work showed the His-tag-VpC-terminal domain lysed the erythrocyte membranes in the blood agar and the phosphate buffered saline (0.9%) media without adding the lecithin substrate of the phospholipase enzyme. Haemolysis occurred at all tested diluted concentrations of His-tag-VpC-terminal domain (p < 0.05), providing evidence for the independent haemolytic activity of the His-tag-VpC-terminal domain. The content of 100 μg of the His-tag-VpC-terminal domain brought the highest haemolytic activity of 80% compared to that in the three remaining contents. Significantly, the His-tag-VpC-terminal domain demonstrated not to involve the phospholipase activity in Luria-Bertani agar supplemented with 1% (vol/vol) egg yolk emulsion. All results proved the vital responsibility of the His-tag-VpC-terminal domain in causing the haemolytic activity without the required activation by the phospholipase enzyme. Raw extracts of Phellinus igniarus and Phellinus pipi at 10-1 mg/mL inhibited the haemolytic activity of the His-tag-VpC-terminal domain from 67.7% to 87.42%, respectively. Hence applying the His-tag-VpC-terminal domain as a simple biological material to evaluate quickly potential derivatives against the Vptlh in vivo conditions will accessible and more advantageous than using the whole of the Vptlh