Vietnam Journal of Science, Technology and Engineering - C

Effects of humidity and temperature on quality factor of micro-beam resonators in atmospheric pressure and gas rarefaction

Fri, 15 Mar 2024 00:00:00 +0700

At atmospheric pressure (p=101325 Pa), the effects of humidity and temperature on moist air become important when discussing the quality factor of micro-cantilever and micro-bridge resonators. The squeeze film damping (SFD) problem, the dominant damping source for micro-beam resonators, is modelled using the modified molecular gas lubrication (MMGL) equation with finite element modelling (FEM) in the eigenvalue problem.

Effect of annealing temperature and doping concentrations on structure and optical properties of Eu3+-doped TiO2 nanomaterials

Fri, 15 Mar 2024 00:00:00 +0700

In this study, we successfully synthesized europium-doped TiO₂(TiO2:Eu³⁺) nanomaterials (NMs) with crystalline sizes ranging from 6.5 to 71.7 nm through a sol-gel method. Analysis of X-ray diffraction (XRD) patterns and ultraviolet-visible (UV-Vis) spectra indicates that the substitution of smaller-sized Ti⁴⁺ions (0.745 Å) by larger-sized Eu³⁺ions (0.947 Å) was more efficient at higher doping concentrations and annealing temperatures...

Analysis of hydraulic drive circuit selection for a carrot collecting system

Ngoc Danh Dang*, Xuan Thiet Nguyen — Fri, 15 Mar 2024 00:00:00 +0700

Compared to conventional mechanical transmissions, hydraulic transmission has the disadvantage of lower energy efficiency. However, it is widely employed in various working machines such as construction machines, off-road vehicles, forest logging machines, and especially agricultural machinery, owing to its flexibility in design, geometric arrangement, and simplicity in operation...

Study on the equilibrium and kinetics of nickel (II) adsorption on cellulose from peanut shell modified with chitosan

Thi Lan Phung*, Thi Kim Giang Nguyen, Phuong Hien Ho, Thanh Nga Pham — Fri, 15 Mar 2024 00:00:00 +0700

In this study, cellulose was produced by activating peanut shells with 5% NaOH as an alkaline agent and bleaching with 5 wt.% H₂O₂. Before being modified with chitosan, the cellulose was slightly oxidized withammonium persulfate to introduce carboxyl groups...

Preparation of pyridinium-based ionic liquid and application as a green catalyst for the synthetic route of 4H-1-benzopyran-5(6H)-ones

Fri, 15 Mar 2024 00:00:00 +0700

1-(4-sulfobutyl)pyridinium chlorozincate ionic liquid was synthesised in high yield (89%) through a simple route and characterised using FT-IR, NMR, and HRMS spectroscopy. The one-pot reaction was employed for the condensation reaction of benzaldehydes, 5,5-dimethyl-1,3-cyclohexanedione, and dicyanomethane, utilising the prepared ionic liquid catalyst...

Antifungal activity of a methanolic extract of Glycyrrhiza uralensis Fisch. root against Fusarium oxysporum and Phytophthora capsici

Fri, 15 Mar 2024 00:00:00 +0700

In the present study, we investigated the antifungal activity of a methanolic extract of Glycyrrhiza uralensis Fisch. root, which inhibited the growth of the plant pathogens Fusarium oxysporum and Phytophthora capsici. The EC 50 values of the G. uralensis Fisch...

Development of direct C-3 difluoromethylation reaction for application in synthesis of quinoline-related drugs

Thanh Tung Truong*, John Nielsen — Fri, 15 Mar 2024 00:00:00 +0700

Fluorine holds a prominent position within the realm of drug discovery and development, substantiated by its presence in approximately 25% of drugs approved by the US Food and Drug Administration (FDA). Consequently, the advancement of new fluorination reactions stands as a pivotal area in medicinal chemistry...

Vietnamese cassava varieties progression across 50 years

Fri, 15 Mar 2024 00:00:00 +0700

Vietnamese cassava varieties constitute the fundamental and pivotal element in the sustainable development programme for cassava. This article aims to encapsulate the advancements made over nearly five decades in breeding and enhancing Vietnamese cassava varieties...

Nursery rearing freshwater prawn, Macrobrachium rosenbergii, in biofloc system integrated with red seaweed, Gracilaria tenuistipitata, at different stocking densities under zero water exchange

Tien Hai Ly, Le Hoang Vu, Ly Van Khanh, Nguyen Thi Ngoc Anh* — Fri, 15 Mar 2024 00:00:00 +0700

This study was conducted to assess the effects of stocking densities on the water quality, survival and growth of the freshwater prawn

Macrobrachium rosenbergii postlarvae (PL) cultured in a biofloc system integrated with red seaweed (Gracilaria tenuistipitata). Postlarvae prawns weighing 0.012±0.001 g were stocked at densities of 1,000, 1,500, 2,000, and 2,500 PL/m³, noted as D1, D1.5, D2, and D2.5, respectively...

RNA isolation by two different methods in analysing adipose-biomarkers of mouse adipose tissues

Dinh Toi Chu, Hue Vu Thi*, Ngoc Hoan Le — Fri, 15 Mar 2024 00:00:00 +0700

The RNeasy Mini Kit and the TRI Reagent protocol are commonly employed techniques for extracting total RNA and are widely utilised in research pertaining to the expression of adipose biomarkers. This study was undertaken to establish and determine an appropriate method for isolating RNA from frozen adipose tissue, with the objective of analysing adipose biomarkers...

Expression of several deubiquitinase and tyrosine phosphatase genes involved in inflammatory response in lymphoma

Nguyen Hoang Giang, Nguyen Thi Xuan*, Nguyen Trong Ha — Fri, 15 Mar 2024 00:00:00 +0700

Lymphoma represents a heterogeneous group of cancers affecting the lymphatic system, encompassing non-Hodgkin lymphoma (NHL) and Hodgkin lymphoma (HL). The majority of NHL cases originate from B cells. HL is characterized by the presence of rare Hodgkin and Reed-Sternberg cells...

Anti-inflammatory effect of gallic acid-conjugated chitooligosaccharides in lipopolysaccharide-stimulated RAW 264.7 macrophages

Fri, 15 Mar 2024 00:00:00 +0700

The aim of the present study is to investigate the anti-inflammatory effect of gallic acid grafted onto COS chains (GA-COS), focusing on the reduction of nitric oxide production, downregulation of inflammatory signals such as inducible nitric oxide synthase (iNOS), gene expression of cytokines such as TNF-α, IL-1β, IL-6, and nuclear factor kappa B (NF-κB) signalling, including the p50 and p65 subunits...

Factors affecting the coagulation of milk protein during quark cheese processing in Vietnam

Fri, 15 Mar 2024 00:00:00 +0700

In recent years, cheese consumption in Vietnam is markedly rising, leading to the attention of local milk processors on cheese making. Quark-type cheese, a traditional food in Central Europe, is a type of well-known acid-coagulated cheese product...

Development of a lateral flow immunoassay with HRP enhancement for spiked SARS-CoV-2 protein N detection in human saliva

Fri, 15 Mar 2024 00:00:00 +0700

The Coronavirus (SARS-CoV-2) is an enveloped RNA virus that caused a dangerous COVID-19 pandemic following an outbreak in Wuhan, China in 2019. In response to the pandemic, the development of lateral flow assays (LFAs) has been crucial for the detection of viruses, commonly targeting the spike (S) or nucleocapsid (N) protein in nasopharyngeal swab (NS) specimens...

Environmental and health impacts of air pollution: A mini-review

Fri, 15 Mar 2024 00:00:00 +0700

Air pollution is one of the leading risk factors for death but also a significant contributor to the global disease burden, affecting quality of life. According to a World Health Organisation (WHO) report, seven million people die from air pollution every year, and 9 out of 10 people worldwide breathe polluted air...