Nha Trang City Research Articles

Remote sensing assessment of wildfire using high-resolution PlanetScope satellite observations: A case study on Co Tien Mountain, Nha Trang City, Vietnam

In this study, high spatial resolution (3 m) PlanetScope (PS) imagery was utilized to map burned areas caused by a wildfire occurring on January 10, 2024, on Co Tien Mountain in Nha Trang city, Khanh Hoa province, South Central Coast of Vietnam. A pre-fire image, acquired ten days earlier, on December 31, 2023, and a post-fire one, acquired nearly one month after, on February 04, 2024, were used to create pre- and post-fire Normalized Difference Vegetation Index (NDVI) maps of the study area, then the difference of NDVI (dNDVI). A threshold (T = 0.20), proposed by the author, was applied to the histogram of the dNDVI product to classify the study area into two clusters: burned pixels (dNDVI > T) and unburned pixels (dNDVI <= T). Classification results estimate that a total of 16.11 ha of grass, reeds, small shrubs and vegetation have been burned out during the wildfire. A field trip is required to map the burned areas using unmanned aerial vehicles (UAVs) for an accurate validation of results derived purely from PS satellite observations. Although lacking a ground truth dataset for validation is a significant limitation, the proposed approach remains beneficial for local managers and decision-makers. It enables the rapid assessment of damages caused by small wildfires and provides essential data for effective disaster management and recovery planning, particularly in remote areas.

Shell shape variation of the symbiotic gastropod Phenacovolva rosea in Vietnam

This study investigates the shell variability of Phenacovolva rosea, a symbiotic gastropod inhabiting octocorals, in relation to geographical location and host coral species. We analyzed shells from 53 adult specimens collected at three locations in the north of Vietnam and one in the vicinities of Nha Trang City (southern Vietnam). To describe the shells' outlines, elliptical Fourier descriptors were applied. Based on the shell outline data, principal component analysis was performed. Additionally, height and width of P. rosea shells were measured. Only the first two principal components were effective, with the first principal component accounting for 92.8% of the variation. It closely correlated with width-to-height ratio of shells. According to dispersion analysis (ANOVA), shells in Nha Trang were significantly slimmer with longer terminal processes compared to those from the three northern locations. The coral host species also impacted shell shape when considering the entire dataset. However, this difference may have stemmed from shell variations between locations, as coral composition is not independent of location. When regional samples were analyzed separately, no significant impact of the host was detected. The factors that differed between northern locations and Nha Trang were then discussed, along with the mechanisms underlying their influence. We suggest that predation risk, influenced by water turbidity, is greater in the clearer waters of Nha Trang. This increased predator pressure may explain the presence of long terminals on P. rosea shells found in Nha Trang, potentially providing protection against some fish predators. Furthermore, the shorter and wider shells found in northern locations may be advantageous in waters with higher current speeds, whereas the long-teminal shells with narrow apertures observed in Nha Trang may be better suited for slower currents. The climate disparity, encompassing temperature and salinity mediated through precipitation, could also potentially influence shell morphology. However, the underlying mechanism remains unclear due to the complex nature of these interactions and the scarcity of literature data. Isolating host-specific shell shape traits from other factors proved challenging, given the close association between host species composition and location. Laboratory experiments modeling each factor independently may provide a solution to this issue.

Could prophylactic antivirals reduce dengue incidence in a high-prevalence endemic area?

Prophylactic drugs against dengue are currently under development. In this study, we explored how such prophylactic approaches might affect dengue cases in four communes of Nha Trang City, Vietnam. A community level dengue transmission survey indicated high levels of previous exposure to dengue (89.7%; 95% CI: 87.2,92.0). We fitted a spatially explicit model to an observed outbreak and simulated likely effectiveness of Case-Area Targeted Interventions (CATI) and One-Time Mass Distribution (OTMD) of drug and vector control strategies. Increasing radius and effectiveness and decreasing delay of CATI was most effective, with drugs being more effective in averting dengue cases than vector control. Using an OTMD approach early in the outbreak required the least number of treatments to avert a case, suggesting that OTMD strategies should be considered as pre-emptive rather than reactive strategies. These findings show that pre-emptive interventions can substantially reduce the burden of dengue outbreaks in endemic settings.

Research on service life prediction and decorative properties of acrylic paint in Vietnam's marine atmosphere by acceleration test

Vietnam is located in a tropical climate zone, especially coastal climates that quickly destroy coating materials that protect steel structures. Therefore, the service life of coatings is always of concern to manufacturers and users. This article presents the results of surveying changes in gloss, color and service life prediction of acrylic paint by accelerated tests, that have simulated according to marine tropical conditions, which are correlated with the atmosphere at Dam Bay station (Hon Tre Island, Nha Trang city, Khanh Hoa province, Vietnam). Gloss is determined according to ISO 2813:2014, and color change is determined according to standard ASTM E308-12. The service life of the acrylic paint system is determined according to standard GOST 9.401-2018. Calculation results based on accelerated test data show that the corrosion time of the acrylic paint system reaches Ri 3 (according to ISO 4628-3:2016 assessment), the service life of acrylic paint Tar 5366 is 2.91 years, and acrylic paint AR-752 is 2.66 years.

The Impact of Brand Value Factors on Online Booking Intention of Domestic Tourists in Nha Trang City, Vietnam

The study clarifies the relationship between brand value and domestic tourists' online booking behavior. There were 450 surveys sent out and 412 surveys were collected. During the data entry and data cleaning process, there were 22 invalid answer sheets. As a result, 390 surveys met the requirements to be used for data analysis. Convenience sampling was used to gather data from 390 visitors who stayed at 15 1 to 2 star accommodations in the city of Nha Trang, Khanh Hoa province, Vietnam. SPSS 22.0 is used to analyze to find the optimal research model and determine the level of impact between the variables in the model. The researcher conducted Cronbach's alpha reliability analysis and EFA exploratory factor analysis to measure and test the convergence of variables. Besides, the researcher conducted regression analysis to test research hypotheses and research models. Finally, there is the T-test and Anova test. The research’s results show that brand awareness, brand image, perceived quality and brand loyalty have, from high to low, impacts on the online booking intention of domestic tourists. In particular, brand awareness has the most positive impact on the online booking intention of domestic tourists, especially after the Covid-19 pandemic. The results contribute to help hotels better understand the components that impact online booking intentions of domestic tourists in Nha Trang through tourists' perception and behaviors when booking online. Simultaneously, the research propose managerial implications and solutions to improve business efficiency of accommodation establishments.

The Urbanization Process in Nha Trang City (Khanh Hoa Province,Vietnam) From 1989 To 1999

In 1989, Khanh Hoa province underwent restructuring to facilitate the full utilization of the region's potential. Despite initial hurdles during the renovation period, the urbanization of Nha Trang city progressed dynamically, spurred by the positive effects of renovation policies, industrialization, and modernization efforts. Transitioning from a type III urban area, by 1999, Nha Trang had advanced to a type II urban area. Industries and services took precedence in the economic landscape, while significant investments were made to upgrade urban infrastructure. Consequently, population density surged, accompanied by gradual enhancements in both the physical and psychological well-being of the populace. Drawing upon information provided by the Khanh Hoa Provincial Statistics Office, the Party Committee of Nha Trang city, and neighborhood administrations, this article employs historical and logical approaches intricately intertwined with analytical, synthetic, and comparative methods. Through this comprehensive framework, the aim is to elucidate the accomplishments and challenges encountered by Nha Trang city throughout its urbanization journey from 1989 to 1999 across various domains.

Experiment of a stepped solar still water distillation divice combine with auxiliary condenser

At the present, there were many research and manufacture subjects the distilled water equipment by using solar energy in Viet Nam. Most of them were designed on traditional type which have a complex shape, cumbersome and low performance. With the aim of this study is to make a simpler, lighter equipment and enhanced production of distilled water, we fabricated a water distillation device which has ladder shape combine with a condensing auxiliary and using solar energy with an area of 1 m2 (evaporation area). The experimental study has established at inclined angles 200, 250, 300 ; circulate and does not circulate steam under conditions at Nha Trang City in 10/2023. The results showed that when the depth distilled water layer is 1cm at the inclined angle 250, the device gave the highest yield, production of distilled water reach 4.9l/m2 (from 7am to 17pm) corresponding to the average radiation of 635W/m2. The efficiency of the distillation equipment with circulation 7.1% higher than does not steam.

Các nhân tố ảnh hưởng đến tiếp cận tín dụng chính thức của hộ ngư dân đánh bắt xa bờ tại thành phố Nha Trang

This study aimed at finding factors affecting the offshore fishing household’s access to formal credit in Nha Trang city. The study used Logit model to measure impacts of independent variables on dependent variables. The analysis results from 120 households show that the proportion of offshore fishing households in the area having access to formal credit is low. Dectected factors include: educational level, professional experience of the head of household, number of trips and voyage time. The research results also suggest that educational policies and credit policies, especially in oder to prevent credit risks and change the perception of fishermen in borrowing, should be considered to improve the offshore fishing household’s access to formal credit in Nha Trang city

Weather Resistance of Organosilicate Coatings in a Tropical Climate Depending on the Choice of the Pigment

The results of a study of the weather resistance of protective and decorative organosilicate coatings prepared using organosilicate compositions based on polydimethylphenylsiloxane as a binder and hydrosilicates as fillers are presented. The color of the coatings varies due to the use of pigments: natural FeOx minerals of yellow, red-brown, and brown shades of flowers. Using X-ray phase and X-ray fluorescence (XRF) analysis, it is established that the composition of minerals is primarily determined by iron oxides in the crystalline modification of hematite (α-Fe2O3) and goethite (α-FeO(OH)). Pigments contain a small number of impurity compounds of a number of elements that contribute to the color range of the coatings. Organosilicate coatings are exposed for 11 months in the tropical climate of two climatic zones of Vietnam (in the suburbs of Nha Trang and Ho Chi Minh City). The high corrosion resistance and color stability of the coatings are established during the entire test period. According to slight changes in the color and gloss, revealed by spectrophotometric and photoelectric methods, it is shown that higher resistance to solar radiation and other adverse climatic factors is typical for coatings with a brown pigment based on hematite; and the lowest, with a yellow pigment based on goethite.

Sea and island economy development with environmental protection in Nha trang city, Khanh hoa province

Sea and island economic development associated with environmental protection is an issue of concern for research. In this article, we will focus on answering three questions: Why should marine and island economic development be associated with environmental protection?; What are the benefits of protecting the marine and island environment for economic development? Is it possible to protect the marine and island environment without economic development or develop an economy without protecting the environment? To answer those three questions, we clarify the reality of economic development associated with environmental protection in Nha Trang city, Khanh Hoa province, the result of the economic development of sea and islands for environmental protection and the effect of environmental protection to the development of sea and island economy.

Wooden traps can replace coral stone traps harvesting the wild lobster seed in mitigating the negative impact on the marine environment

Lobster seacage aquaculture has a significant social-economic contribution to many coastal communities throughout the central provinces of Vietnam. One of the issues of lobster aquaculture is that the industry entirely relies on the wild juvenile lobster (lobster seed) captured using traps made of coral stones, which affects the coastal ecology and environment. The present study was carried out to compare the catch efficiency of traps made of round timber poles (wooden trap) with conventional dead corals (coral stones) during the juvenile lobster fishing season in 2019 in the coastal area of Nha Trang city, Vietnam. Results showed that experimental wooden traps maintained the conventional catch rate level, with a significant proportion of Panulirus ornatus caught at larger carapace length than those caught by the coral stone traps. Our findings show the biological and environmental benefits of using alternative fishing methods would eliminate collecting coral stones to make lobster seed traps and contribute to coastal protection while maintaining the fishing operation and seed supplies for the lobster seacage farmers.

Logistics and Legitimation: Religious Pluralism in the Bà Tower, Nha Trang City, Vietnam

Abstract: Today, in the space of Poh Nagar Stupa in Nha Trang City, Khánh Hòa province, Vietnam, there exists a diverse abundance of religious practices. For many people from Bóng village and the Vietnamese communities who work as seafarers around the area, the deity located in the Stupa is the holy Mother Thiên Y A Na Diễn Ngọc Phi, a local goddess. For other Việt, especially the members of the Patronage Association of the Bà Stupa, the Goddess that they worship in the main Stupa is the embodiment of Nam Hải Guan Yin Bodhisattva. In the consciousness and practices of the Chăm people, especially the Chăm groups from Ninh Thuận and Bình Thuận provinces, the supreme deity in the Stupa is their Poh Nagar Goddess of Land. In tandem with this diversity of religious beliefs is a symbiosis of different ritual practices. The Chăm people practice the ritual in the traditional way of worshiping the Poh Nagar Mother Goddess of the Land. The Việt people of the Patronage Association practice Buddhist rituals. The ritual practice of the Bóng villagers follows procedures for rituals dedicated to the tutelary God of a Việt traditional village festival. Viewed from the practitioner's perspective, the co- existence of the diversity of religious practices at the Stupa reveals an ongoing need for compromise and sometimes contestation.

Morphological Alterations of Fish Erythrocytes as Their Response to Environmental Conditions

Fish bodies respond to changes in environmental conditions in various ways and degrees. Seven fish species were collected from three study locations, including two nearshore sites (Ha Tinh province and Nha Trang city, Khanh Hoa province) and one offshore site (Toc Tan island, Khanh Hoa province) to evaluate alterations in erythrocyte morphology under certain environmental conditions. Heavy metal concentrations at all study sites were analyzed and met the acceptable technical criteria for each site. Fish blood samples were taken from the tail veins, anticoagulated with heparin, and stained with Giemsa stain. The blood cell morphological study was performed using an optical microscope. The results revealed two types of morphological abnormalities of fish erythrocytes, including nuclear deformation and nuclear-matter distribution.

Phân bố cá ở hạ lưu sông Cái, thành phố Nha Trang, tỉnh Khánh Hòa 12

The lower Cai river in Nha Trang city, which is transitional water area between the freshwater area and the marine protected area of Nha Trang Bay, has an extremely important role in the socio-economic development of this region. And plays an abundant source of nutrition for coastal fish. This study was carried out at 09 sites, representing 03 watersheds (marine, brackish, and freshwater), with continuous monthly sampling from July to December 2019. The results show that the distribution of fish in the study area was influenced by time and space factors, the composition of fish species caught in the dry season was more diverse than in the rainy season, and the water near the estuary (salt water, brackish) was more diverse than the freshwater. The proportion of fish ecological groups was significantly different between sampling periods and sampling locations. Among 155 fish species recorded, 70 species have migratory phenomena to reproduce and find food. In which, the group of species moving between sea and river to find food accounts for the highest proportion with 26 species (16.8%). This result is the first scientific basis for the distribution of fish in the lower Cai River, Khanh Hoa Province, contributed to providing a data source for research, protection, and sustainable exploitation of fish resources in this area.

Environmental factors influence the local establishment of Wolbachia in Aedes aegypti mosquitoes in two small communities in central Vietnam.

Background: The wMel strain of Wolbachia has been successfully introduced into Aedes aegypti mosquitoes and subsequently shown to reduce transmission of dengue and other pathogens, under both laboratory and field conditions. Here we describe the entomological outcomes of wMel Wolbachia mosquito releases in two small communities in Nha Trang City in central Vietnam. Methods: The wMel strain of Wolbachia was backcrossed into local Aedes aegypti genotype and mosquito releases were undertaken by community members or by staff. Field monitoring was undertaken to track Wolbachia establishment in local Ae. aegypti mosquito populations. Ecological studies were undertaken to assess relationships between environmental factors and the spatial and temporal variability in Wolbachia infection prevalence in mosquitoes. Results: Releases of wMel Wolbachia Ae. aegypti mosquitoes in two small communities in Nha Trang City resulted in the initial establishment of Wolbachia in the local Ae. aegypti mosquito populations, followed by seasonal fluctuations in Wolbachia prevalence. There was significant small-scale spatial heterogeneity in Wolbachia infection prevalence in the Tri Nguyen Village site, resulting in the loss of wMel Wolbachia infection in mosquitoes in north and center areas, despite Wolbachia prevalence remaining high in mosquitoes in the south area. In the second site, Vinh Luong Ward, Wolbachia has persisted at a high level in mosquitoes throughout this site despite similar seasonal fluctuations in wMel Wolbachia prevalence. Conclusion: Seasonal variation in Wolbachia infection prevalence in mosquitoes was associated with elevated temperature conditions, and was possibly due to imperfect maternal transmission of Wolbachia. Heterogeneity in Wolbachia infection prevalence was found throughout one site, and indicates additional factors may influence Wolbachia establishment.

Factor Structure and Measurement Invariance of the Very Short Form of Infant Behavior Questionnaire-Revised (IBQR-VSF): A Study among Vietnamese Children.

The Infant Behavior Questionnaire-Revised (IBQ-R) assesses the temperament of infants in Western and non-Western countries. Although its factor analyses revealed three factors—surgency, negative affectivity, and effortful control—in the Western culture, the degree to which these are universal or culturally specific is unclear. This study developed a Vietnamese version of the IBQ-Revised Very Short Form (R-VSF) and examined its factor structure in a Vietnamese population. The Vietnamese IBQ-R VSF was administered to 292 mothers of infants between the ages of 3 and 18 months in Nha Trang city, Vietnam, between July and September 2019. After deleting items to achieve sufficient Cronbach’s alphas for each scale (surgency, negative affectivity, and orienting/regulation), the remaining 28 items were aggregated to parcels subjected to exploratory factor analyses (EFAs). EFAs revealed a 3-factor model corresponding to the original theory, and confirmatory factor analyses indicated a good fit of this structural model. The final 3-factor model with parcels indicated measurement and structural invariance between mothers of boys and girls.

Positive Parenting Program to Promote Child Development Among Children 1 to 3 Years Old: A Quasi-Experimental Research.

Introduction:Child development receives lack of concern and the role of parents in promoting child development is not frequently mentioned in Vietnam. This study aimed to examine the effectiveness of Positive Parenting Program to Promote Child Development on maternal knowledge and practice and development of children aged 1 to 3 years.Methods:This is a quasi-experimental study conducted in Nha Trang city, Vietnam. There are a total of 60 mothers whose children were identified as suspected developmental delayed participated in the study. There were 30 mothers who attended the program as experimental group and 30 mothers who joined the study as comparison group. Ages and Stages Questionnaires, Third Edition (ASQ-3) were applied to assess the child development. Descriptive analysis and paired and independent-samples t-test were applied to examine the research objectives.Results:The findings suggested that after the program implementation, the maternal knowledge of child development and child development of the experimental group were significantly higher than pre-program and the improvements of these variables were better than the comparison group (P < .05) while the maternal practice to promote child development was significantly better only within the experimental group.Conclusions:The program was effective in improving several maternal outcomes and child development. The study recommends applying the Positive Parenting Program to Promote Child Development to enhance mother’s knowledge of child development and child development.

Blood cells and some hematological parameters of red drum (Linnaeus, 1766) in Vietnam.

This research focuses on hematological characteristics, erythrocyte morphology and some biochemical parameters of red drum Sciaenops ocellatus (Perciformes: Sciaenidae), cultured in natural water environment in areas near river mouth (L1), estuaries (L2) in Ha Tinh province and coastal areas (L3) in Nha Trang city, Khanh Hoa province of Vietnam. A total of 18 speciments were examined in research, six in each location. Blood was drawn from the tail vein, using a microscope to research morphology and automated gauges to determine blood biochemical parameters. Analysis of blood samples showed that the rate of red drum's erythrocyte morphology disorders in all three locations was quite high. The two main types of disorders were nuclear deformity and nuclear-matter distribution. Changes in erythrocyte size, shape and nuclear were related to salt concentration at culture locations. Blood hemoglobin content was stable in all three regions. Other hematological parameters such as the number of erythrocytes, blood biochemical parameters (glucose, SGOT, SGPT, urea, creatine, plasma iron, albumin, and protein) have differences among the locations, which showed the different reactions of the same species with different environmental conditions.

Environmental factors influence the local establishment of Wolbachia in Aedes aegypti mosquitoes in two small communities in central Vietnam

Background: The wMel strain of Wolbachia has been successfully introduced into Aedes aegypti mosquitoes and subsequently shown to reduce transmission of dengue and other pathogens, under both laboratory and field conditions. Here we describe the entomological outcomes of wMel Wolbachia mosquito releases in two small communities in Nha Trang City in central Vietnam. Methods: The wMel strain of Wolbachia was backcrossed into local Aedes aegypti genotype and mosquito releases were undertaken by community members or by staff. Field monitoring was undertaken to track Wolbachia establishment in local Ae. aegypti mosquito populations. Ecological studies were undertaken to assess relationships between environmental factors and the spatial and temporal variability in Wolbachia infection prevalence in mosquitoes. Results: Releases of wMel Wolbachia Ae. aegypti mosquitoes in two small communities in Nha Trang City resulted in the initial establishment of Wolbachia in the local Ae. aegypti mosquito populations, followed by seasonal fluctuations in Wolbachia prevalence. There was significant small-scale spatial heterogeneity in Wolbachia infection prevalence in the Tri Nguyen Village site, resulting in the loss of wMel Wolbachia infection in mosquitoes in north and center areas, despite Wolbachia prevalence remaining high in mosquitoes in the south area. In the second site, Vinh Luong Ward, Wolbachia has persisted at a high level in mosquitoes throughout this site despite similar seasonal fluctuations in wMel Wolbachia prevalence. Conclusion: Seasonal variation in Wolbachia infection prevalence in mosquitoes was associated with elevated temperature conditions, and was possibly due to imperfect maternal transmission of Wolbachia. Heterogeneity in Wolbachia infection prevalence was found throughout one site, and indicates additional factors may influence Wolbachia establishment.

Validation of an analytical method for the determination of inorganic, organic, and total arsenic in fish sauce based on hydride generation atomic absorption spectrometry

An atomic absorption spectrometric (AAS) method was performed to determine the total, inorganic, and organic arsenic in fish sauce. The total organic arsenic was calculated from the total and inorganic arsenic values quantified using the hydride generation AAS (HG-AAS). Under optimal experimental conditions at the absorbance wavelength of 193.7 nm, the concentration of inorganic arsenic in fish sauce ranged from 0.05 to 1.2 mg/L, with a limit of detection (LOD) of 0.015 mg/L. The detectable total arsenic concentrations varied widely, ranging from 0.03 to 2.5 mg/L with the LOD of as low as 0.01 mg/L. The practical applicability of the method was demonstrated with the recovery in the range from 97 to 102% for inorganic arsenic, and 97 to 101% for organic arsenic. The method was applied to the analysis of commercial products from Nha Trang, Phan Thiet, and Phu Quoc City, Vietnam. The total organic arsenic in fish sauce samples determined by HG-AAS was compared with the results of liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP/MS). The f-test and t-test showed null hypothesis for acceptable variance and mean at a confidence level of 95%. The results showed that the HG-AAS method had high efficiency, accuracy, and sensitivity in quantifying inorganic and total organic arsenic in fish sauce using simple instrumentation.