Preliminary data on the aquatic invertebrate fauna of the Ma River, Thanh Hoa province: Research article

A field survey for the invertebrate fauna conducted in the Ma River, Thanh Hoa province in 2013. The research applied multivariable analysis performed by the Primer v.6 software, such as CLUSTER, one-way ANOSIM, BEST and DIVERSE. The results showed a list of 138 aquatic invertebrate species. Of these, most were freshwater wide-distributing species coupled with others characterized for brackish and marine waters. The biodiversity status was quite high compared to several other rivers in the North of Vietnam. The list contained many economic-valued species and 2 of these were listed in the Red Data Book of Vietnam. The aquatic invertebrates showed a significant relation to the two different combinations of physiochemical factors for zooplanktons and zoobenthos, respectively. The values of the species number, abundance and Shannon-Weiner index for both of zooplanktons and zoobenthos showed a curved trend from the upper river segments to lower river segments. These figures for zooplanktons peaked in the middle river segments, whereas the numbers for zoobenthos achieved the highest numbers in the estuaries. The species composition of the estuaries differentiated significantly from that of other freshwater habitats.Năm 2013 đã tiến hành một đợt điều tra khu hệ động vật không xương sống sông Mã, tỉnh Thanh Hóa. Nghiên cứu sử các phân tích đa biến thông qua phần mền Primer v.6, bao gồm: CLUSTER, one-way ANOSIM, BEST và DIVERSE. Kết quả phân tích thu được 138 loài với thành phần loài chủ yếu là những loài nước ngọt thường gặp và phân bố rộng, ngoài ra còn có các loài đặc trưng cho nước lợ và mặn. Trong số các loài thu được, nhiều loài có giá trị kinh tế và 2 loài có tên trong Sách Đỏ Việt Nam. Khu hệ động vật không xương sống sông Mã có quan hệ chặt với hai nhóm chỉ số thủy lý hóa học khác nhau, tương ứng cho động vật nổi và động vật đáy. Giá trị các chỉ số sinh học gồm số lượng loài, mật độ và Shannon-Weiner hồi quy theo đường cong phi tuyến từ thượng lưu tới hạ lưu; đạt giá trị cao nhất tại cửa sông đối với động vật đáy và vùng trung lưu với động vật nổi. Thành phần loài cửa sông khác biệt rõ rệt với thành phần loài các sinh cảnh nước ngọt khác

Застосування методів багатокритеріального прийняття рішень при виборі мастильно-охолоджуючої емульсії

Many machining processes would not be possible without the presence of cutting oils. There are many diffe­rent types of cutting oils on the market today, each with different properties. The difference of oils is manifested in many parameters such as viscosity, combustion temperature, recyclability, pollution tendency, stability, price, etc. Choosing the best oil is a difficult and tedious task for customers. In this work, we present the results of a study on the selection of cutting oil using multi­criteria decision­making (MCDM) methods. The selection of the best oil is made on the basis of ranking of seven different types. Two MCDM methods used in this study are Proximity Indexed Value (PIV) and Collaborative Unbiased Rank List Integration (CURLI). This two methods have been used to rank cutting oils. These are two methods with completely different characteristics. When using the PIV method, it is necessary to standardize the data and determine the weights for the criteria. Meanwhile, if using the CURLI method, these two tasks are not needed. In addition, three different weight methods were also used to calculate the weights for the criteria including EQUAL, Rank Order Centroid weight (ROC weight) and Rank Sum weight (RS weight). These three methods have been used to determine the weights for the criteria of cutting oil. The PIV method was used three times corresponding to three different weight methods. The results showed that out of the four ranking results (three using the PIV method and one using the CURLI method), the same best oil was unani­mously identified. It is recommended that the CURLI method should be used if weighting of criteria and data normalization are not desiredБагато процесів механічної обробки були б неможливі без наявності мастильно­охолоджуючих емульсій. Сьогодні на ринку представлено безліч різних видів мастильно­охолоджуючих емульсій, кожна з яких володіє різними властивостями. Різниця між емульсіями проявляється у багатьох параметрах, таких як в’язкість, температура горіння, можливість переробки, схильність до забруднення, стійкість, ціна тощо. Вибір кращої емульсії є складним та стомлюючим завданням для покупців. У даній роботі представлені результати дослідження щодо вибору мастильно­охолоджуючої емульсії з використанням методів багатокритеріального прийняття рішень (MCDM). Вибір кращої емульсії проводиться на основі ранжування семи різних видів. У дослідженні використовувалися два методи MCDM: індексоване за близькістю значення (PIV) та спільна інтеграція незміщеного списку рангів (CURLI). Ці два методи використовуються для ранжування мастильно­охолоджуючих емульсій і мають абсолютно різні характеристики. При використанні методу PIV необхідно стандартизувати дані та визначити ваги критеріїв. Тим часом, при використанні методу CURLI ці два завдання не потрібні. Крім того, для розрахунку ваг критеріїв також використовувались три різні вагові методи, включаючи рівний (EQUAL), вагу центроїда порядку ранжування (вага ROC) та вагу суми рангів (вага RS). Дані три методи також використовувалися для визначення ваг критеріїв мастильно­охолоджуючої емульсії. Метод PIV застосовувався тричі відповідно до трьох різних вагових методів. Результати показали, що з чотирьох результатів ранжування (три з використанням методу PIV і один з використанням методу CURLI) була одноголосно визначена одна і та ж краща емульсія. Метод CURLI рекомендується використовувати, якщо не потрібне зважування критеріїв та нормалізація дани

The COVID-19 Pandemic and Its Impacts on Tourism Business in a Developing City: Insight from Vietnam

The COVID-19 pandemic has generally destroyed the global tourism industry and threatened the recovery of destinations in developing countries facing more challenges from increasingly serious waves of the pandemic. Although many studies have attempted to measure the general impacts of COVID-19, very little research has been conducted to assess its overall impact on specific tourism destinations throughout many waves of the pandemic. This research aims to explore how a tourism economy in a developing country context has been damaged after many waves of COVID-19. A typical emerging city in Vietnam experiencing three waves of the COVID-19 pandemic was selected as a case study. The study recruited 40 representatives of tourism-related organizations for in-depth interviews, while 280 questionnaires were distributed to participants from different tourism organizations. The findings indicate that the majority of tourism businesses in the examined case study seriously suffered from the pandemic, and very few tourism-related enterprises were able to recover after the first wave of infection. Unfortunately, the tourism business sectors were found to be on the brink of bankruptcy or facing permanent shutdown after the third wave. All tourism enterprises generally appeared to experience a sharp drop in the number of customers, tourism revenue, service facilities and exploitation, as well as employee downsizing, but the degree of downturn differed among the examined enterprises. Among the tourism enterprises, travel agencies and the accommodation sector were found to suffer the greatest economic losses compared to other stakeholders. In general, the COVID-19 pandemic’s impact on the tourism business in Vietnam is a big concern, which may require a timely economic policy response and financial scheme to better support local enterprises in coping with the challenges during post-pandemic recovery

The COVID-19 Pandemic and Its Impacts on Tourism Business in a Developing City: Insight from Vietnam

The COVID-19 pandemic has generally destroyed the global tourism industry and threatened the recovery of destinations in developing countries facing more challenges from increasingly serious waves of the pandemic. Although many studies have attempted to measure the general impacts of COVID-19, very little research has been conducted to assess its overall impact on specific tourism destinations throughout many waves of the pandemic. This research aims to explore how a tourism economy in a developing country context has been damaged after many waves of COVID-19. A typical emerging city in Vietnam experiencing three waves of the COVID-19 pandemic was selected as a case study. The study recruited 40 representatives of tourism-related organizations for in-depth interviews, while 280 questionnaires were distributed to participants from different tourism organizations. The findings indicate that the majority of tourism businesses in the examined case study seriously suffered from the pandemic, and very few tourism-related enterprises were able to recover after the first wave of infection. Unfortunately, the tourism business sectors were found to be on the brink of bankruptcy or facing permanent shutdown after the third wave. All tourism enterprises generally appeared to experience a sharp drop in the number of customers, tourism revenue, service facilities and exploitation, as well as employee downsizing, but the degree of downturn differed among the examined enterprises. Among the tourism enterprises, travel agencies and the accommodation sector were found to suffer the greatest economic losses compared to other stakeholders. In general, the COVID-19 pandemic’s impact on the tourism business in Vietnam is a big concern, which may require a timely economic policy response and financial scheme to better support local enterprises in coping with the challenges during post-pandemic recovery

Outcomes of gamma knife radiosurgery for drug-resistant primary trigeminal neuralgia

Objective: To evaluate the result of gamma knife radiosurgery (GKRS) for drug-resistant primary trigeminal neuralgia (TN). Methods: Patients who were diagnosed with drug-resistant primary TN were treated with GKRS at the Nuclear Medicine and Oncology Center, Bach Mai Hospital from January 2015 to June 2020. Using the pain rating scale of the Barrow Neurological Institute (BNI), follow-ups and evaluations were conducted at 1 month, 3 months, 6 months, and 9 month, and 1, 2 years, 3 years, and 5 years after radiosurgery. Comparisons of pain levels was performed before and after radiosurgery according to the BNI scale. Results: From January 2015 to June 2020, 33 patients were treated with GKS. There were 23 female patients and 10 male patients; the average age was 61.9. The average onset time of disease was 4.42 years. Among all patients, 84.8% of patients were relieved from pain and 78.8% were pain-free without medication. The mean time for pain relief was 3 months and was not related to the dose of GKS (<80 Gy and ≥80 Gy). The efficacy of pain relief is not related to blood vessel contact with the trigeminal nerve, the dose of GKS, and the onset of disease. The rate of recurrence after the first pain relief was low (14.3%). Conclusions: Gamma knife is an effective method for the treatment of primary drug-resistant TN, especially in elderly patients with underlying medical conditions. The analgesic effect does not depend on the presence of nerve-vascular conflict

Fractional Order Active Disturbance Rejection Control for Canned Motor Conical Active Magnetic Bearing-Supported Pumps

Active magnetic bearings (AMBs) are electromagnetic mechanism systems in which non-contact bearings support a rotating shaft using attractive forces generated by electromagnets through closed-loop control. For complete support of a five degree of freedom (DOF) rotor system, most AMB structures include two radial actuators and one for the axial direction. Conical active magnetic bearings (CAMBs) is one of the development directions of conventional magnetic bearings in which the requirement of the axial bearing can be eliminated. In this paper, we propose a structure with a CAMB integrated into a canned motor pump to eliminate the need for mechanical bearings and shaft seals. However, this system necessitates a more complicated control strategy due to a significant coupling effect between rotor motion and hydrodynamic disturbances. This paper presents a fractional order active disturbance rejection control (FOADRC) including a fractional order extend state observer (FOESO) and a proportional derivative controller (PD) to track and reject lumped disturbances actively. The proposed controller achieves better performance than the integer-type ADRC and traditional PID controller. The control performance of the proposed FOADRC is illustrated in terms of very good disturbance rejection capability that is demonstrated through MATLAB/Simulink simulation results

Magnetic nanoparticles embedded in microlasers for controlled transport in different sensing media

In recent years, whispering gallery mode microlasers have attracted tremendous interest in sensing due to their ultra-high sensitivity at atomic levels. However, due to the non-magnetic properties, it is difficult to locate the microlasers at hard-to-reach positions, thus, limiting their sensing potential in many in-vitro and in-vivo applications. In this work, we report magnetic microlasers fabricated by encapsulating Ni0.2Zn0.8Fe2O4 magnetic nanoparticles (MNPs) within their cavity made of bovine serum albumin. The presence of MNPs allows the transportable actuation of the magnetic microlasers while maintaining lasing emission characteristics. Microlasers with various concentrations of MNPs are investigated to identify the optimum concentration that can balance a good magnetization, a low lasing threshold, and a high quality (Q) factor. These magnetic microlasers can be employed for sensing applications where sensors need to be navigated through different sensing media. As a proof of concept, we observed a clear shift of lasing wavelength of a magnetic microlaser while dragging it through different adjacent media by magnetic navigation. This result demonstrates the potential applications of magnetic microlasers for future biological and chemical applications.11Nsciescopu

The Effect of Multiwalled Carbon Nanotubes on the Thermal Conductivity and Cellular Size of Polyurethane Foam

Polyurethane (PU) foam is known as the popular material for the applications in many fields of industry and life. To improve the mechanical and thermal properties of this material, in this research, PU foam was reinforced with aniline-modified multiwalled carbon nanotubes (MWCNTs). Fourier transform infrared FTIR spectrum of modified MWCNTs showed the aniline was grafted on the surface of MWCNTs through the appearance of –NH2 stretches. The effect of MWCNTs with and without modification on the density, porosity, compressive strength, and heat conductivity of PU/MWCNT foam nanocomposites was investigated. The dispersibility of MWCNTs in the PU matrix was enhanced after modification with aniline. Compressive strength of PU nanocomposite reached the highest value after adding 3 wt.% of modified MWCNTs into PU foam. Besides, the water uptake of PU nanocomposites using 3 wt.% of MWCNTs was decreased to 13.4% as compared to that using unmodified MWCNTs. The improvement in thermal conductivity of PU/aniline-modified MWCNT nanocomposite was observed due to the change in the cellular size of PU foam in the presence of MWCNTs as shown by SEM images

Metagenomic analysis of bacterial community structure and diversity of lignocellulolytic bacteria in Vietnamese native goat rumen

Objective In a previous study, analysis of Illumina sequenced metagenomic DNA data of bacteria in Vietnamese goats’ rumen showed a high diversity of putative lignocellulolytic genes. In this study, taxonomy speculation of microbial community and lignocellulolytic bacteria population in the rumen was conducted to elucidate a role of bacterial structure for effective degradation of plant materials. Methods The metagenomic data had been subjected into Basic Local Alignment Search Tool (BLASTX) algorithm and the National Center for Biotechnology Information non-redundant sequence database. Here the BLASTX hits were further processed by the Metagenome Analyzer program to statistically analyze the abundance of taxa. Results Microbial community in the rumen is defined by dominance of Bacteroidetes compared to Firmicutes. The ratio of Firmicutes versus Bacteroidetes was 0.36:1. An abundance of Synergistetes was uniquely identified in the goat microbiome may be formed by host genotype. With regard to bacterial lignocellulose degraders, the ratio of lignocellulolytic genes affiliated with Firmicutes compared to the genes linked to Bacteroidetes was 0.11:1, in which the genes encoding putative hemicellulases, carbohydrate esterases, polysaccharide lyases originated from Bacteroidetes were 14 to 20 times higher than from Firmicutes. Firmicutes seem to possess more cellulose hydrolysis capacity showing a Firmicutes/Bacteroidetes ratio of 0.35:1. Analysis of lignocellulolytic potential degraders shows that four species belonged to Bacteroidetes phylum, while two species belonged to Firmicutes phylum harbouring at least 12 different catalytic domains for all lignocellulose pretreatment, cellulose, as well as hemicellulose saccharification. Conclusion Based on these findings, we speculate that increasing the members of Bacteroidetes to keep a low ratio of Firmicutes versus Bacteroidetes in goat rumen has resulted most likely in an increased lignocellulose digestion