Science & Technology Development Journal: Natural Sciences

Vaccine for enterotoxigenic Escherichia coli causing post-weaning diarrhea (PWD) in piglets

2024-07-10T04:01:37+07:00

Post-weaning diarrhea (PWD) in piglets is primarily caused by the enterotoxigenic Escherichia coli (ETEC) strains. ETEC expresses adhesins attached to the intestinal mucosa, specifically fimbriae such as F4, F5, F6, F7 and F18. F4 and F18 are particularly prevalent in strains that cause PWD. ETEC then releases enterotoxins that play a central role in the pathogenic process, such as heat-labile enterotoxin (LT), heat-stable enterotoxin (ST), and a small amount of enteroaggregative heat-stable toxin 1 (EAST1), which lead to dehydration, electrolyte imbalances, damage to the intestine, reduced nutrient absorption, growth rate, and resulting in death. Vaccination is the most effective preventive measure against PWD. Although there is an existing ETEC vaccine based on fimbrial immunization, enterotoxins are the primary cause of diarrhea in ETEC. Therefore, the development of new-generation vaccine that target both adhesins and enterotoxins has been carried out. In recent years, many studies have successfully generated fusion antigens of these two factors and tested for their ability to induce immune responses in mouse, rabbit, and pig models. Along with the development of targeted M cell strategies, this opens a promising new direction for the creation of both general and specific ETEC oral vaccines. In this paper, the development strategies for vaccines based on fimbrial adhesins and enterotoxins to protect piglets from PWD are summarized. These studies also serve as a basis for the development of ETEC vaccines in humans.

Preparation of cellulose nanocrystal/ silver nanoparticle composite as a catalyst for 4-nitrophenol reduction

2024-07-10T03:49:18+07:00

This paper presented the cellulose nanocrystals (CNC) were synthesized from the Vietnamese agricultural waste, sugarcane bagasse, by a chemical method and then acid hydrolysis. The composite based on CNC and Ag (CNC/Ag) was fabricated by directly synthesizing Ag−NPs on the CNC template with the support of a cationic surfactant, hexadecyltrimethylammonium bromide (CTAB). The morphology, chemical structure and composition of the materials were analyzed by physicochemical methods, ultraviolet-visible spectroscopy (UV-Vis), X-ray diffraction (XRD), Fourier−transform infrared spectroscopy (FT−IR), and transmission electron microscopy (TEM). The TEM image results determined that the CNC material was a fibre with an average length and diameter of 400 ± 12 nm and 10 ± 2 nm, respectively. The CNC/Ag composite was used as a catalyst in the 4-nitrophenol (4-NP) reduction to produce 4-aminophenol (4-AP). The 4-NP reduction reaction in the presence of the CNC/Ag catalyst followed a pseudo-first-order reaction kinetics where the catalytic rate constant (kapp) and the catalytic activity factor (k) were 0.25 ± 0.02 min-1 and 20.82 ± 1.4 min^-1. g^-1, respectively. The CNC/Ag catalyst helped this reaction to overcome the kinetic barrier by directly transferring electrons from the BH4− ion to 4-NP through the Ag NPs as an intermediate. In addition, the CNC/Ag material showed the antibacterial activity against both Gram-positive bacteria, Staphylococcus aureus and Gram-negative bacteria, Escherichia coli.

Study on genetic diversity of Rose varieties (Rosa spp.) in Sa Dec, Dong Thap using PCR-RAPD technique

2024-07-10T04:06:05+07:00

Roses (Rosa spp.) are highly valuable ornamental plants known for their diverse flower shapes and colors. Rose plants are widely used in Vietnam for decoration, essential oil production, and the cosmetics industry. In Sa Dec Flower Village (Dong Thap province), the Roses plant plays a crucial role in the agricultural economy development. Therefore, techniques for cultivating and developing new varieties of Roses are increasingly emphasized, focusing on diversification to increase the collection of varieties, diversify types and species, preserve forms, and enhance economic efficiency. In this study, PCR-RAPD technique was used on 18 Sa Dec’s rose varieties, resulting in a total of 66 polymorphic bands, with 87.88% being polymorphic and 12.12% monomorphic. The dendrogram analysis revealed that the 18 rose varieties from Sa Dec could be divided into two main groups with several smaller subgroups. The correlation between genetic variations in the genome and morphological markers of the 18 rose varieties was analyzed and discussed. The results lay the initial background for understanding the genetic relationships among 18 rose varieties from Sa Dec Flower Village, which could serve as a foundation for collecting, preserving, and developing genetic resources, as well as selecting and designing hybrid pairs to create new rose varieties in Sa Dec Flower Village.

Collection of human derived acellular dermal matrix by a combination of ultrasonic technique and sodium dodecyl sulfate solution

2024-07-10T04:19:26+07:00

Extracellular matrix (ECM) from the human skin is a potential source of materials for regenerative medicine in some applications: treatment of skin loss lesions, replacement of lost tissues or 3D bioprinting ink preparation. The ECM could only be used when the cellular component that induced the immune response was removed. Common decellularization methods could be divided into three categories: physical, chemical, and biological. This study showed that these categories could attain optimal when they were combined together rather than be individually used. This paper presented the study in which the human skin was collected and preserved in 1X phosphate buffered saline (PBS) supplemented with antibiotics in 24 hours. After that, the obtained skin samples were decellularized by three methods including using ultrasonic combining with sodium dodecyl sulfate (SDS) solution, hypertonic NaCl solution combining with SDS solution and a trypsin solution at some concentrations. The cell reduction efficiency was assessed by a histological staining and quantification of residual DNA concentrations. The results showed that the ultrasonic combining with SDS completely removed the cellular component and better preserved the structure of the ECM and the ECM was not cytotoxic to human fibroblasts in vitro. The result could be the basis for obtaining the acellular ECM from human skin for biomedical applications.

Effect of magnetic field on the quantum capacitance of silicene

2024-07-10T04:33:27+07:00

This paper presents a theoretical study of the quantum magnetocapacitance of spin and valley-polarized silicene in an external perpendicular magnetic field. From the low−energy effective electronic Hamiltonian, the energy spectrum and the wave function of electrons in a monolayer of silicene have been computed in detail. The numerical results show that the electric and magnetic fields have a strong influence on the energy spectrum of electrons. For example, the band gap could be adjusted by the external electric field, and the energy levels exhibit spin splitting, including the zero level. The electronic properties of silicene differ from those of the well-known graphene due to the strong intrinsic spin-orbit interaction and buckled structure of silicene, graphene is a monolayer material with a flat geometric structure, and the spin–orbit interaction is so small that it can be ignored. By analyzing the density of states function, the quantum capacitance is evaluated in relation to Shubnikov–de Haas oscillations calculated using the Poisson summation formula. The numerical results indicated that when the electric field energy was larger than the spin–orbit interaction energy, the capacitance was zero at the Fermi energy level E_F = 0. This indicated that the presence of spin−orbit and electric field interactions lead to the emergence of a beating pattern at low magnetic fields and a peak would split at the higher fields. This behavior could be attributed to the interference of Shubnikov–de Haas oscillations at the two frequencies of the split Landau levels. The calculation presented in this paper on the quantum capacitance of silicene was also valid for germanene with an even stronger spin–orbit coupling .

Synthesis of copper/silica nanocomposites for application in preventing Ralstonia solanacearum bacteria causing the wilt disease

2024-07-10T04:42:07+07:00

This paper presented the synthesis at room temperature of copper/silica (Cu/SiO2) nanocomposites by the chemical reduction method with sodium borohydride as a reducing agent and polyvinylpyrrolidone as a stabilizer. The physicochemical properties of Cu/SiO2 were studied through ultraviolet–visible absorption spectrum, X-ray diffraction pattern, Fourier transform infrared spectrum, transmission electron microscope and energy-dispersive X-ray spectrum. Analytical results indicated that Cu/SiO2 contained copper nanoparticles with an average size of 6.78 nm, evenly distributed in the silica structure through chemical bonds. The antibacterial activity of Cu/SiO2 was evaluated by testing its activity against Ralstonia solanacearum bacteria that caused the wilt disease in plants. Cu/SiO2 could completely inhibit the growth of R. solanacearum bacteria at a concentration of 36 ppm, two times more effective than copper nanoparticles. The results showed that Cu/SiO2 nanocomposites would be potential for practical applications to replace traditional chemical pesticides in agriculture.

Synthesis of TiO2/C composite material for capacitive deionization (CDI) technology

2024-07-14T20:29:20+07:00

Hybrid Capacity Deionization (HCDI), a water treatment method currently undergoing significant development, offers advantages in efficiency and the desalination speed. With its high specific surface area and excellent electrical conductivity, carbon-based materials such as graphene, activated carbon (AC), carbon nanotubes (CNTs) and their composite materials are being used as electrodes in the HCDI. This paper presented the synthesis of a composite of TiO2 and some carbon materials like graphene, carbon black (C65) and CN using the sol-gel method for HCDI electrodes. The results showed that the TiO2/C composite could store energy via both a double-layer capacitance and a pseudocapacitance mechanism, with a maximum specific capacitance of 101.7 F.g-1 when using TiO2/CNTs as the electrode in a 1 M Na2SO4 solution at a scan rate of 5 mV.s-1. The salt adsorption was investigated with a 200 ppm NaCl solution, and the specific adsorption capacity (SAC) and the average salt adsorption rate (ASAR) of this electrode at 1.2 V were 27.1 mg.g-1 and 7.10 mg.g-1.min-1, respectively. Based on these results, the TiO2/C composite material has potential for use as an electrode material in salt adsorption processes.

Effect of gamma irradiation dose on strawberry preservation

2024-07-14T20:39:15+07:00

Strawberries are well-known to people all over the world for their distinct flavor and nutritional value. Preserving strawberries and extending its shelf life has been a huge challenge due to its perishable nature. To reduce spoilage of strawberries during storage, farmers around the world usually use synthetic chemicals to minimize such losses and extend storage time. However, chemical treatments can have harmful health risks. The purpose of this work was to evaluate the effect of gamma irradiation doses ranging from 0 Gy to 1,600 Gy on the shelf life, microbial inactivation, weight loss, total soluble solids (TSS), titratable acidity, and pH value of strawberries stored at room temperature. In this research, 60Co isotope source was used to evaluate the effect of gamma-irradiation on the physicochemical properties of strawberries for a maximum period of 15 days. Strawberries were exposed to gamma irradiation at dose levels of 200 Gy, 400 Gy, 600 Gy, 800 Gy, 900 Gy, 1,000 Gy, 1,100 Gy, 1,200 Gy, 1,400 Gy, and 1,600 Gy for the treatment of strawberry berries that are an agricultural product of Dalat city. The results show that strawberry berries irradiated with 1,000 Gy had significantly prolonged storage life of 12 days when compared to non-irradiated strawberry (3 days). Non-irradiated strawberry samples showed maximum decay of 70%, and weight loss of 15.2% at only the 6th day of storage. The storage time and gamma irradiation dose also had a significant effect on the titratable acidity and pH of the strawberries. Results showed that radiation doses of 1,000 Gy might be used as consumer- acceptable doses for shelf life extension, minimum weight loss and decay, without affecting the chemical quality of strawberry.

Chemical constituents from ethyl acetate extract of stems of Uvaria micrantha (A. DC.) Hook. f. et. Thoms.

2024-07-15T03:33:31+07:00

Ky huong, scientifically known as Uvaria micrantha (A. DC.) Hook. F. et. Thoms., belongs to the Annonaceae family, is utilized in traditional medicine, and is employed in herbal remedies for purposes such as relieving respiratory issues, aiding digestion, and alleviating pain. Studies on the chemical composition of U. micrantha have revealed the presence of compound groups such as benzoquinones, triterpenoids, chalcones, flavonoids, oxoaporphine alkaloids, hydroxycinnamic acid amides, and acetogenins. These compounds found in U. micrantha have been associated with anti-cancer properties, particularly against blood and breast cancer cells. Despite the medicinal potential of U. micrantha, there is a limited amount of research on this species both in Vietnam and globally. Therefore, a new study has been conducted to investigate the chemical components of the U. micrantha, contributing to the enrichment of its overall value. Through the use of silica gel column chromatography combined with thin-layer chromatography using various solvent systems, five pure compounds were obtained from the ethyl acetate extract. Based on 1D NMR and MS spectral data, along with comparison to reference materials, the chemical structures of these five compounds were identified as oleanoic acid (1), lup-20(29)-en-3-ol (2), stigmastane-3,6-dione (3), stigmast-4-en-3-one (4), and 1H-indole-3-carbaldehyde (5). All five compounds are reported here for the first time as isolated from the Ky huong.

Some polyphenolic compounds isolated from the whole plant Balanophora fungosa

2024-07-15T03:46:35+07:00

Balanophora fungosa, commonly known as "Ngọc cẩu" or "Dó đất" in Vietnamese, is a parasitic plant belonging to the Balanophoraceae family. This plant was found in mountainous regions of the Northern and Central Highlands provinces in Vietnam. Traditionally, B. fungosa has been utilized in folk medicine, mainly for the enhancement of vitality, hemorrhage treatment, fever reduction, abdominal pain alleviation, and general body pain relief. There are few studies that reported the presence of bioactive compounds in this species, including triterpenoid and polyphenolic compounds, and their biological activities were antioxidant, anti-inflammatory, and melanin synthesis inhibition. In this research, the chemical composition of the EtOAc extract of B. fungosa was investigated, leading to the isolation of 10 compounds comprising p-hydroxybenzaldehyde (1), p-hydroxybenzoic acid (2), vanillic acid (3), syringic acid (4), cinnamic acid (5), p-coumaric acid (6), caffeic acid (7), ferulic acid (8), 4-hydroxy-3-methoxycinnamaldehyde (9), and ω-hydroxypropioguaiacone (10). The structural compounds had been elucidated using nuclear magnetic resonance spectroscopy and comparison with previous references. This study contributes to the database of natural compound structures, particularly those constituents isolated from B. fungosa. All compounds, except for 5 - 7, are new ones found in the whole plant of B. fungosa now.