A Study on Factors Impacting on Profitability: The Case of Vietnam

This study is conducted to investigate factors influencing the profitability of the Vietnamese food processing firms. Data was collected from audited financial statements from listed food processing firms on the Vietnam Stock Exchange. Panel regression model was applied in this study (PLS). The testing methods used in this research were Pearson model; Modified Wald Test, Wooldridge test (for autocorreclation in panel data), Hausman model, especially the relationship between FEM and REM as well as Multicollinearity test based on VIF coeficient. The results shows that DR, SDR and LDR have negative impacts on profitability. In contrast, TDTELT have positive impacts on the profitability. FATA and SIZE impact return on asset (ROA) without statistical significance. SIZE has positive impact on return on equity (ROE) while it impacts negatively on profit margin (PM). Moreover, AGE, GDP growth, and inflation do not have impact on profitability. Keywords: Factors, Return on assets, Food processing firms, Vietnam DOI: 10.7176/RJFA/11-10-07 Publication date:May 31st 202

Spatiotemporal evolution of SARS-CoV-2 Alpha and Delta variants during large nationwide outbreak of COVID-19, Vietnam, 2021

We analyzed 1,303 SARS-CoV-2 whole-genome sequences from Vietnam, and found the Alpha and Delta variants were responsible for a large nationwide outbreak of COVID-19 in 2021. The Delta variant was confined to the AY.57 lineage and caused >1.7 million infections and >32,000 deaths. Viral transmission was strongly affected by nonpharmaceutical interventions

Evaporation-induced assembly of colloidal clusters into superclusters with nonconvex deltahedral geometry

Using small colloidal clusters with dumbbell, triplet, tetrahedral, octahedral geometry as elementary building blocks, we investigate the templated-assisted cluster-cluster aggregation into hierarchical clusters, namely superclusters, by means of Monte Carlo simulations. We find that the colloidal superclusters made of dumbbells and triplets produces a unique structural motif that is similar to that of clusters of single colloids, whereas the superclusters composed of tetrahedral and octahedral clusters possess a more complex structure. However, despite their complexity, such structures can be predicted based on a decomposition using triplets as a core and the number of initial “building block” clusters. In particular, a majority of the observable superclusters are members of a particular category of nonconvex deltahedra (Cundy deltahedra). These findings could be useful in preparation of complex colloidal molecules

Systematic and zoogeographical characteristics of the oribatid mite fauna (Acari: Oribatida) of Vietnam

The article is a synthesis of the studies on oribatid mites carried out in Vietnam during the period of 1980-2013, and is based on the oribatid materials obtained throughout the country. The oribatid mite fauna (Acari: Oribatida) of Vietnam is diversified, and has high specialization. It is diverse by the number of superfamilies, families, genera and species recorded. However, the number of genera per family, as well as the number of species and subspecies per genus, is not high. 43.75% and 37.50% of the total 64 families and subfamilies consist of one and of 2-3 genera, respectively. The only one family Oppiidae Grandjean, 1954 consists of 23 genera. The majority of the genera, 68.10% of the total, are represented by one species. The only two genera are represented by more than 10 species, namely Galumna Heyden, 1826 and Pergalumna Grandjean, 1936, with 13 and 11 species, respectively. The main zoogeographical characteristics of the oribatid mite fauna of Vietnam are the Oriental species, representing 60.30% of the total number. It also includes the elements of the Palaearctic – Oriental (12.2%), the Cosmopolitan (10.6%), the Afrotropical (Ethiopical) – Oriental (6.9%), the Australian – Oriental (5.0%), the Neotropical – Oriental (3.8%), the Nearctic – Oriental (0.9%), and the Pacific - Oriental (0.3%).Để đánh giá cấu trúc phân loại và đặc điểm địa động vật của khu hệ ve giáp Việt Nam (Acari: Oribatida), trên cơ sở mẫu vật nghiên cứu thu từ toàn lãnh thổ quốc gia, công trình đã tổng hợp và phân tích các kết quả nghiên cứu về ve giáp trong giai đoạn 1980-2013. Khu hệ động vật ve giáp Việt Nam có tính chuyên biệt cao, và rất đa dạng về số lượng họ, giống và loài xác định được. Tuy nhiên số lượng giống trong 1 họ, cũng như số lượng loài trong 1 giống lại không cao. 43,75% và 37,50% của 64 họ và phân họ, tương ứng chỉ xác định được có 2 và 3 giống. Duy nhất có họ Oppiidae Grandjean, 1954 ghi nhận được 23 giống. 68,10% tổng số giống, chỉ xác định được 1 loài. Duy nhất có 2 giống ghi nhận được hơn 10 loài, là Galumna Heyden, 1826 và Pergalumna Grandjean, 1936, tương ứng có 13 và 11 loài. Đặc điểm địa động vật cơ bản của khu hệ ve giáp Việt Nam là tính chất Đông phương (Oriental), với 60,30% tổng số loài xác định được. Tính chất địa động vật của nó còn bao gồm các yếu tố sau: Cổ bắc - Đông phương (Palaearctic-Oriental, 12,2% tổng số loài xác định được), Toàn cầu (Cosmopolite, 10,6%), Nhiệt đới Phi châu - Đông phương (Afrotropical (Ethiopical)-Oriental, 6,9%), Úc châu - Đông phương (Australian-Oriental, 5,0%), Tân nhiệt đới - Đông phương (Neotropical-Oriental, 3.8%), Vùng cực - Đông phương (Nearctic-Oriental, 0.9%), và Thái Bình Dương - Đông phương (Pacific-Oriental, 0,3%)

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 effects of high temperature on cardiovascular admissions in the most populous tropical city in Vietnam

This study examined the short-term effects of temperature on cardiovascular hospital admissions (CHA) in the largest tropical city in Southern Vietnam. We applied Poisson time-series regression models with Distributed Lag Non-Linear Model (DLNM) to examine the temperature-CHA association while adjusting for seasonal and long-term trends, day of the week, holidays, and humidity. The threshold temperature and added effects of heat waves were also evaluated. The exposure-response curve of temperature-CHA reveals a J-shape relationship with a threshold temperature of 29.6 °C. The delayed effects temperature-CHA lasted for a week (0–5 days). The overall risk of CHA increased 12.9% (RR, 1.129; 95%CI, 0.972–1.311) during heatwave events, which were defined as temperature ≥ the 99th percentile for ≥2 consecutive days. The modification roles of gender and age were inconsistent and non-significant in this study. An additional prevention program that reduces the risk of cardiovascular disease in relation to high temperatures should be developed

Optimization of Dressing Parameters for Minimum Surface Roughness and Maximum Material Removal Rate in Internal Grinding of SKD11 Tool Steel

This paper introduces a study on multi-objective optimization of dressing parameters in internal grinding of SKD 11 tool steel using Grey based Taguchi method. The L27 orthogonal array of the Taguchi method was selected to design the experiments. The input parameters of the dressing process are the depth of fine, the time of fine dressing, the depth of coarse dressing, the time of coarse dressing, non-feeding dressing, and dressing feed rate. The output factors are surface roughness (SR) and material removal rate (MRR). A grey relation grade was determined by using the signal-to-noise ratio. The ANOVA was applied to find out the effect of input factors on the grey relation grade. In conclusion, the fine dressing times is the parameter that has the strongest impact on multiple performance characteristics, followed by the coarse dressing times. Also, the optimum dressing parameters to get minimum SR and maximum MRR is the depth of coarse dressing of 0.03mm, the time of coarse dressing of 2 times, the depth of fine dressing of 0.01 mm, the time of fine dressing of 2 times, non-feeding dressing of 2 times, and dressing feed rate of 1.2mm/min

Synthesis and Characterization of Broccoli-like Ag/Cu₂O Nanostructures on ZnO Nanowires Using the Plasma–Liquid Interaction Method

We have designed an excellent visible-light-driven and high-performance photocatalyst with a Ag-Cu2O-ZnO nanowire heterostructure in our work by combining the hydrothermal approach with plasma–liquid technology. The structural and morphological characteristics and optical properties of the samples were evaluated using X-ray diffraction, field-emission scanning electron microscopy, and spectrophotometry, respectively. The results show that the Ag nanoparticles are mainly positioned on the Cu2O nanoclusters compared with the ZnO nanowire surface, forming broccoli-like Ag-Cu2O nanoclusters during the Ar gas plasma treatment process in an aqueous solution. The diameter of the Ag/Cu2O nanoclusters ranges from 150 to 180 nm. The Ag-Cu2O-ZnO nanowires exhibited improved photocatalytic performance, decomposing approximately 98% methyl orange dye in 30 min. This is a consequence of the synergistic interactions between the p-n heterojunction formed at the Cu2O-ZnO interfaces and the localized surface plasmon resonance (LSPR) effect of the Ag nanoparticles, which broaden the visible light absorption range and effectively separate the photogenerated charge carriers