Search

Abstract Background Effective management strategies are crucial in minimizing the adverse consequences associated with the leafhopper, Amrasca devastans (Dist.) (Hemiptera: Cicadellidae). Economic limitations to entomopathogenic fungi production present a substantial challenge, particularly in developing countries. This study aimed to investigate a cost-effective solid-state fermentation (SSF) for large-scale production of Purpureocillium lilacinum PL1 conidia to manage A. devastans infestations in okra cultivation. Results Rice and maize were demonstrated as highly suitable substrates for producing conidia densities of over 2 × 1010 conidia g−1. Furthermore, the influence of agricultural phytosanitary agents on the growth rates of P. lilacinum PL1 was evaluated. Certain pesticides were ineffective on the expansion of P. lilacinum PL1 colonies, while fungicides exhibited complete inhibition. The laboratory investigation revealed that 1 × 107 conidia ml−1 of P. lilacinum PL1 exhibited a success rate of 88.66% in decreasing the population of A. devastans nymphs in vitro. Furthermore, field investigations carried out in okra plantations demonstrated that the utilization of P. lilacinum PL1 at the concentration of 1 × 107 conidia ml−1 of resulted in a significant reduction of the pest nymph population by 72.87% subsequent to the 2 applications. Conclusion In conclusion, the cost-effective mass production of P. lilacinum PL1 conidia through SSF presents a promising solution for managing A. devastans infestations in okra farming, particularly in economically challenged regions.

Seasonal changes in freshwater phytoplankton assemblages at Tuyen Lam Reservoir in the Central Highlands of Vietnam were classified into 23 functional groups based on physiological, morphological, and ecological characteristics. A total of 168 species were recorded during 10 surveys from 2015 to 2019 at 7 sampling sites, with Chlorophyta dominating in number of species. Phytoplankton abundance varied from 0.18×105 to 21.2×105 cells/L during the study period, mainly due to cyanobacteria. Seven of the 23 functional groups were considered to be dominant (relative density > 5%). The dominant functional groups were groups M and G in the dry season and groups M, G, P, and E in the rainy season. Group M (Microcystis aeruginosa) was the most common in both seasons, while group P (Closterium, Staurastrum, Aulacoseira), group E (Dinobryon, Synura), and group G (Sphaerocystis, Eudorina) were more common in the rainy season. The Shannon diversity index (H¢) showed that phytoplankton communities were relatively diverse and that most of the study sites were lightly polluted. However, the ecological status has deteriorated at some locations due to the overgrowth of group M, leading to eutrophication in this reservoir. This study highlights the usefulness of functional groups in the study of seasonal changes in phytoplankton dynamics. Functional groups are applied for the first time at Tuyen Lam Reservoir and can be used to predict early-stage cyanobacterial blooms in future studies.

Objective There are no reports on the burden of suicidal ideation and suicide attempts in the general population of French Polynesia (FP). We aimed to improve suicide prevention and mental health care by assessing the prevalence of suicide risk and major mental health disorders and care among adults in FP. Methods We conducted the Mental Health in General Population Survey in FP during 2015 to 2017. Participants were selected using the quota method to obtain a representative sample of the general population. Suicide risk and psychiatric diagnoses were assessed using the Mini International Neuropsychiatric Interview. Results We included 968 people aged 18 years or older. The prevalence of current suicidal ideation (13.1%) and current (2.6%) and lifetime suicide attempts (18.6%), as well as mental health disorders (42.8%), was high in FP. A notable proportion of participants with these conditions did not seek medical assistance. Conclusion A high prevalence of suicide risk and mental health disorders was found in the general population of FP. Suicide prevention and mental health plans are needed in FP that include better access to primary care for the diagnosis and treatment of mental health disorders. Further research is needed to clarify cultural risk and protective factors.

Steel-concrete composite beams are ubiquitous in construction, especially in bridge building. This paper addresses the harvesting of energy from a beam subjected to a moving harmonic load using analytical methods. The harvesting is performed by attaching a thin piezoelectric patch directly to the bottom surface of the steel beam. Based on the assumptions of the Euler-Bernoulli beam theory for the relationship between displacement and deformation, the differential equation for the vibration of a beam is derived using Hamiltonian principles. A theoretical formulation is presented for the problem of harvesting energy from a harmonic moving load on a simply supported beam. The dynamic responses are determined in exact form using analytical methods, and the energy harvested from the piezoelectric material layer is calculated. The influence of the speed of the load on the energy harvesting of the piezoelectric material layer is investigated in detail. [ABSTRACT FROM AUTHOR]

This paper deals with an analytical approach to the static behavior of Steel Concrete Composite (SCC) slabs. The Classical Plate Theory (CPT) and Refined Plate Theory (RPT) are considered when constructing governing equations describing the behavior of steel concrete plates. The displacement fields are represented by trigonometric series to find the exact solution by applying Navier's approach. Various numerical examples have been compared with the considered ones showing their high accuracy. The influence of plate parameters such as the thickness of steel and concrete layers on displacement was investigated in detail. [ABSTRACT FROM AUTHOR]

Phaeocystis globosa is a marine phytoplankton species that forms deleterious blooms in temperate and tropical waters. In some locations, "giant" colonies form, although the controls on its size are unknown. During a "giant" colony bloom, measurements were completed to characterize photosynthesis–irradiance relationships, nitrogen uptake kinetics, and nitrogen–irradiance relationships of P. globosa colonies to understand its growth characteristics and their relationship to colony size. The photosynthetic capacity (Fv/Fm) varied from 0.65 to 0.68 among colony sizes ranging from 3.0 to 11.0 mm, indicating that all colonial cells were physiologically robust. The maximum chl a‐specific photosynthetic rates (PmaxB) ranged from 0.89 to 1.92 μg C · μg−1 chl · h−1, were maximal in the mid‐sized colonies (5.5–6.5 mm) and decreased with size. The relatively low PmaxB values may be related to the high cellular chl a of colonial cells and their acclimation to in situ irradiance. Nitrate Vmax and KS values were greater than those of ammonium, although N affinity was greater for ammonium. No differences in light‐limited rates in either nitrate or ammonium uptake among colony sizes were observed, and no dark uptake occurred. Both ammonium and nitrate uptake showed a saturation response as a function of irradiance. While the driving forces for the formation of giant colonies remain unknown, their impacts on coastal systems are substantial and a further assessment of their growth is warranted. [ABSTRACT FROM AUTHOR]

Phaeocystis globosa is an important bloom‐forming marine phytoplankton species that often accumulates to large levels in temperate and tropical waters and has significant impacts on food webs and biogeochemical cycles. It can form "giant" colonies that reach 3 cm in diameter. Microscopic observations, colony elemental composition, and pigment composition were analyzed to assess the characteristics of colonies as a function of colony size. Particulate organic carbon (POC) per unit surface area, colonial cell density, and chlorophyll a per unit surface area all increased with colony size, in contrast to results from temperate waters. Cellular chl a averaged 0.85 pg chl · cell−1. Colonies had both photosynthetic and protective pigments, with fucoxanthin being the dominant accessory pigment. Based on chl a and pigment levels, it appears colonies were acclimated to relatively low irradiances, likely due to their life cycle and the extremely turbulent environment in which they grew. Mucous carbon ranged from 16.2% to 79.2% of the total POC, and mucous carbon per unit surface area increased with colony size, suggesting that the mucous envelope did not thin as the colony grew. Based on elemental composition, nitrogen did not appear to limit growth, but phosphorus:carbon ratios were similar to those of P‐limited cultures. Giant colonies represent an extreme response to the environment, but they do not appear to have greatly different characteristics than other tropical strains. [ABSTRACT FROM AUTHOR]

This empirical study aims to identify and evaluate the crucial factors that influence customer satisfaction and loyalty in homestays in Da Lat City. The research utilizes the SERVQUAL framework, and related research suggests seven factors: responsiveness, assurance, empathy, tangibles, satisfaction, and loyalty. A PLS-SEM structural model is used to test hypotheses by evaluating data from 250 residents of Ho Chi Minh City. The finding points out that adolescents' loyalty to homestay services in Da Lat is stimulated directly by empathy and satisfaction and indirectly by responsiveness and assurance. Meanwhile, young people's satisfaction with homestay service is affected by 4 out of 5 factors: responsiveness, assurance, empathy, and tangibles. This study provides insights into homestay services and the key elements influencing young customers' satisfaction levels toward loyalty to the homestay. Homestay managers should use this model approach to restructure and improve their homestay services to meet the demands and desires of their target clients in a competitive marketplace. [ABSTRACT FROM AUTHOR]

This paper develops a finite element method for double beams subjected to static loading. The double beam consists of two Euler-Bernoulli beams connected continuously by an elastic spring connection. The finite element for a double beam is formulated with eight degrees of freedom based on the Euler-Bernoulli beam theory. The finite element method is implemented in MATLAB software to analyze the behavior of the double beams. The MATLAB code calculates the displacements of both the upper and lower beams. Numerical examples are compared with the analytical solution to demonstrate the high accuracy of the proposed method. [ABSTRACT FROM AUTHOR]