Subtropical Areas Research Articles

Experimental investigation on vibration characteristics of sympodial tree

Sympodial trees are prevalent in tropical and subtropical urban areas while suffering the threat of wind storms every year, which leads to unpredictable economic losses and secondary hazards. However, the research on the dynamics of sympodial tree, which exhibits extremely complex structures, is limited. Therefore, this study conducts wind tunnel tests to systematically investigate vibration characteristics for trees with different crown configurations. Results show that as the scaled Cauchy number increases, the base overturning moment coefficient (CM) gradually reduces, yet its reduction rate decreases. Subsequently, a higher spectral peak and narrower bandwidth of CM is observed with the extent of pruning severity. Finally, an energy coefficient (CE) is developed to depict the wind energy absorption ability of trees. It is revealed that CE displays a declining trend with an increase in LAI1 (leave area / ground area) and LAI2 (leaf area / frontal area). Furthermore, it is found that trees characterized by robust and squat trunks along with dense foliage possess an enhanced capacity for wind energy dissipation.

Occurrence and management of the emerging pathogen Epicoccum sorghinum.

Epicoccum sorghinum is a notorious fungal pathogen that causes leaf spot symptoms on a wide range of plants, leading to devastating losses in crop production and quality. Here, all reports regarding the occurrence and management of E. sorghinum are covered for the first time. E. sorghinum has been detected in tropical and subtropical climate areas during the rainy season, mainly from March to August, since 2016. Although E. sorghinum shows broad host spectrum, the disease incidence is especially notorious in cereal crops and ornamental plants, suggesting that these plants are especially susceptible. Control methods based on synthetic fungicides, plant extracts, and microbial biocontrol agents have been reported. However, most agents were applied using only in vitro conditions, restricting the information about their actual applicability in field conditions. Additionally, E. sorghinum can colonize cereal grains and synthesize the carcinogenic mycotoxin tenuazonic acid, posing an enormous hazard for human health. Furthermore, although E. sorghinum is an emerging pathogen that is currently causing yield penalties in important crops, there is lack of information about its pathogenic mechanisms and virulence factors, and there is currently no commercial antifungal agent to manage E. sorghinum. Collectively, it is imperative to conduct in vivo studies to determine the efficacy of antifungal agents and the most effective methods of application in order to develop suitable management strategies against E. sorghinum.

Seroprevalence and Clinical Profile of Leptospirosis and Scrub Typhus in Clinically Suspected Patients at a Tertiary Care Center: A Retrospective Study from Theni, Tamil Nadu

Abstract Background: Leptospirosis and Scrub typhus are zoonotic illnesses that are found worldwide. Scrub typhus is a rickettsial infection caused by Orientia tsutsugamushi and spread through the biting of a mite’s chigger. Leptospirosis is an anthropozoonotic illness that can be found anywhere but is most common in tropical and subtropical areas. In this study, we report the seroprevalence of Scrub typhus and Leptospirosis with relation to demographic factors in clinically suspected patients attending a tertiary care hospital in Theni, Tamil Nadu. Methods: This is a retrospective study in which 9574 serum samples from clinically suspected cases were collected from January 2018 to December 2023 and tested for immunoglobulin M (IgM) antibodies for Scrub typhus using the enzyme-linked immunosorbent assay (ELISA) and rapid test. A blood sample was taken from each patient, and an IgM ELISA was performed to make the diagnosis. The ELISA cut-off was determined. Results: In this study, 9574 probable cases, 4306 were examined for Leptospira IgM ELISA and 5268 for Scrub typhus IgM ELISA. Out of 4306 suspected Leptospira cases, 167 (3.8%) were positive and 485 (9.2%) were positive in 5268 suspected Scrub typhus cases. The bulk of Leptospirosis and Scrub typhus cases were in the 21–40 years’ age range, followed by the 0–20 years’ age range. Males were found to have higher seroprevalence (57.1%) than females (42.9%). Conclusions: Scrub typhus and leptospirosis are developing infections, and prompt treatment can save many lives. It is strongly advised to take a programmatic approach to the prevention, control, and management of these developing diseases.

Integrating multispectral remote sensing and geological investigation for gold prospecting in the Borongo-Mborguene gold field, eastern Cameroon

Multispectral remote sensing data has great promise for mineral prospecting via regional-scale mapping of alteration zones and geological structures, once the method is calibrated using in-situ geological observations. The Borongo-Mborguene area, located in eastern Cameroon at the transition from sub-tropical to arid climates, hosts several alluvial gold deposits. In this investigation, maps developed by processing of Landsat-8 OLI images, ASTER satellite images, and SRTM DEM data were compared to results of a comprehensive field survey to locate zones of hydrothermal alteration and regional structural lineaments, and to verify the association of these features with gold mineralization. Specific Landsat-8 and ASTER band ratios, as well as principal component analysis of the multispectral images, were selected to isolate spectral signals that characterize particular groups of alteration minerals, such as clays, hydrated carbonates, hydrated sulphates, iron oxides, and iron hydroxides. Lineaments and their preferred orientations were extracted by filtering of the digital elevation data. A fuzzy logic approach was subsequently applied to the ensemble of resulting maps to highlight five areas of concentrated hydrothermal alteration and structural complexity as potential gold prospects (Mborguene, Boutila, Nandoungue, Borongo and Ouaden villages). Petrographic study of samples collected from the remotely-identified alteration zones revealed a hydrothermal ore assemblage of gold, galena, pyrite and hematite in mineralized quartz veins. Structural control of the alteration zones in the Borongo-Mborguene gold field was confirmed by field mapping along a shear zone. Hence, our petrographic and field studies indicate that the multispectral remote sensing data and data processing methods developed herein are appropriate for mineral exploration in remote sub-tropical areas of Africa. More generally, the computationally efficient and simple procedure developed here should yield accurate preliminary maps of the spatial distribution of hydrothermal halos and related mineral deposits in challenging mixed-type vegetated terrain around the globe.

Análise epidemiológica e hematológica de cães naturalmente infectados por Hepatozoon spp. da região central do Brasil – estudo retrospectivo

Hepatozoonosis is a hemoparasitosis caused by intracellular protozoa of the genus Hepatozoon, transmitted to dogs and other carnivores by parasitized ticks, such as Rhipicephalus sanguineus and Amblyomma spp. Its prevalence varies by geographic region, favoring tropical and subtropical areas. Hepatozoon spp. infection cause nonspecific clinical manifestation. This longitudinal retrospective study aims to highlight the epidemiological and hematological aspects of dogs naturally infected with Hepatozoon spp. in the municipality of Mineiros, state of Goiás, Brazil, between 2018–2022. This study considered the following information: age, sex, breed, distribution of cases over the years, seasonality, and hematological profile. A total of 272 domestic dogs were found to be parasitized by Hepatozoon spp. using the blood smear technique. Adult dogs were more likely to be affected by hepatozoonosis, with no breed or sexual predisposition. This study showed an exponential increase in cases diagnosed over the years, particularly in autumn and winter (the dry season). Within the study’s evaluation criteria, most dogs had anemia, thrombocytopenia, and hyperproteinemia; however, there were no changes in the total leukocyte count.

Climate Variability and Malaria Transmission: Unraveling the Complex Relationship

Climate change, an emerging issue, significantly impacts international health, particularly malaria, a critical issue that affects tropical and subtropical areas. Researchers have identified climate variability as a major determinant of malaria transmission and distribution. This review aims to disentangle the interplay between climate variability and malaria transmission, with a focus on temperature, rainfall, humidity, and extreme weather events and their influence on the Anopheles mosquito and Plasmodium parasites' life cycles. Writing this review article involved consulting several scientific databases and compiling information from them. Thus, incorporating data from epidemiology, ecology, climatology, and public health, this paper aimed at integrating knowledge on how climatic factors influence malaria incidence, distribution, and transmission density. This study emphasizes the importance of cross-disciplinary approaches in addressing these issues and highlights the need for synergy in implementing climate change mitigation, improved health care systems, advanced surveillance, and community mobilization to mitigate and manage malaria in the changing climate. Awareness of the factors determining climate variability and their relationship with malaria transmission patterns is important in formulating adequate strategies to cushion the impact of climate change on malaria incidence and secure world health.

A Study of Growth and Yield of Four Peanut Varieties with Rhizobia Inoculation under Field Conditions

The symbiotic nitrogen fixation between rhizobia and peanuts offers an advantage in reducing nitrogen fertilizer inputs, decreasing the incidence rate of peanuts, and enhancing soil fertility. Inoculating rhizobia agent is an effective pathway to improve both the quality and yield of peanuts, contributing to food security and promoting sustainable agricultural practices. This study conducted a one-year field experiment in a subtropical humid monsoon climate area in Southeast China to investigate the effects of rhizobia agents on the growth and crop yield of four peanut varieties (i.e., Taihua No.4, No.6, No.8, and No.10). Our research showed that inoculation with rhizobia agent can increase the plant height, lateral branch length, fresh root weight, and leaf area of the four peanut varieties. Meanwhile, inoculation with a rhizobia agent can significantly (p < 0.05) increase the ~50% number of root nodules. Especially for the early-maturing and drought-resistant variety, Taihua No.4 exhibited the highest number of nodules and peanut fruits per plant in the pod-setting stage after inoculation with rhizobia agent, i.e., 24.5 and 18.0, respectively. Under the conventional fertilization conditions (N-P2O5-K2O 15-15-15, 450 kg/hm2), Taihua No.4 and No.6 inoculated with rhizobia agent achieved higher yield increase rates of 11.0% and 11.6% compared to other peanut varieties. This study indicated that the Taihua No.4 and No.6 are the most suitable peanut varieties for rhizobia inoculation and promotion, with enormous potential for yield increase. Meanwhile, optimizing rhizobia inoculation techniques and evaluating soil health status, economic benefits of peanuts, and applicable regions should be explored in the future.

Extreme climate events and future population exposure under climate change in the Huaihe River basin of China based on CMIP6 multimodel ensembles projections

AbstractThe Huaihe River basin (HRB) of China located in the climate transition zone between warm temperate and subtropical areas is highly sensitive to climatic change. However, the changes in future climate extreme events under anthropogenic warming and the population exposure to these climate extremes in HRB remain unexplored. Here, using the eight commonly used extreme climate indices and based on the bias‐corrections of 16 global climate models (GCMs) in CMIP6, we present a projection and uncertainty analysis of extreme events and investigate the corresponding population exposure risk in HRB under three shared socioeconomic pathways (SSP1‐2.6, SSP2‐4.5, SSP5‐8.5). The 16‐GCM ensemble mean projects an evident warming trend under all three scenarios with a total increase of 25.6–68.0 days in summer days (>25°C) by the end of the century in HRB. Larger increases (decreases) in maximum and minimum temperatures (frost days) are projected in the western HRB. Very heavy rain days (R20mm), maximum 5‐day precipitation (RX5day) and simple daily intensity index (SDII) will experience intensification across most of HRB (especially in southern and western HRB). The consecutive dry days is projected to decrease in northwestern HRB and increase in southern HRB. However, there is a large spatial variability in GCM uncertainty with a higher SSP scenario generally having higher uncertainty. Increases in summer days and R20mm exacerbate population exposure in HRB in near future (2030–2059), but in far future (2070–2099) although summer days (R20mm) continues to rise, population exposure is expected to decrease due to the rapid decline in population density.

Dengue in Wardha City: Addressing Social and Clinical Challenges

Dengue fever, a major public health concern in tropical and subtropical areas, is a critical issue in Wardha city. The purpose of this study was to analyze Wardha inhabitants’ awareness, knowledge, and habits about dengue illness. The survey, which took place between November 2023 and April 2024, used a structured questionnaire and was delivered to a representative sample of 50 participants from various wards of the city. The questionnaire inquired about respondents’ knowledge of dengue symptoms, mechanisms of transmission, preventative measures, and attitudes toward local dengue control initiatives. Preliminary data show that, while many locals are aware of dengue and its symptoms, there are significant gaps in knowledge about effective preventative techniques, as well as widespread misunderstandings regarding transmission. The poll also preventative measures. Furthermore, the survey found diverse degrees of community engagement in dengue management operations, with many respondents advocating for more thorough and accessible teaching campaigns. These findings show the critical need for targeted educational initiatives and increased community engagement in Wardha city to improve dengue prevention and control. Public health experts and politicians are encouraged to use these findings to create and execute more effective, context-specific dengue control measures.

Illness perceptions of people living with chronic heart failure and limited community disease management.

To explore the cognitive representations and emotional responses to living with chronic heart failure of people receiving limited community disease management. Individuals living with heart failure face self-care and emotional challenges due to the overwhelming nature of adapting to lifestyle changes, particularly in subtropical areas. Qualitative descriptive. We applied Leventhal's Common Sense Model of Self-Regulation as the framework for interviews and analyses. Twenty patients with chronic heart failure were interviewed during a hospital admission for exacerbation of their condition in a tertiary hospital in Thailand. Analysis of the components of Leventhal's model of cognitive representations of illness revealed two themes relating to Illness Identity: (1) lack of knowledge of the diagnosis and how to recognise symptoms of the disease, and (2) recognition of symptoms of an exacerbation of CHF was based on past experience rather than education. These resulted in delays responding to cardiac instability and confusion about the intent of treatment. Participants recognised the chronicity of their disease but experienced it as an unrelenting cycle of relative stability and hospitalisations. Perceived Controllability was low. Two themes were: (1) Low perceived trust in the efficacy of medical treatment and lifestyle changes, and (2) Low perceived trust in their ability to comply with recommended lifestyle changes. The Consequences were significant emotional distress and high burden of disease. The two themes of emotional responses were (1) Frustration and hopelessness with the uncertainty and unpredictability of the disease, and (2) Sense of loss of independence, functional capacity and participation in life's activities. Chronically ill patients need support to understand their illness and make better treatment and lifestyle decisions. Improving patients' self-efficacy to manage treatment and symptom fluctuations has the potential to improve their mental well-being and minimise the impact of their condition on suffering and participation in employment and community. Leventhal's Common Sense Model of Self-Regulation can be used to examine cognitive and emotional elements of illness perceptions, which link to individuals' ability to make informed decisions about disease management and influence health behaviours. Understanding illness perceptions underpins strategies for enhancing and sustaining self-management behaviours. The study findings accentuate the need to establish long-term condition support programs in low-middle income countries where the burden of heart failure is increasing exponentially. The Consolidated Criteria for Reporting Qualitative Research (COREQ) guideline was used to explicitly and comprehensively report our qualitative research. Patients contributed to the conduct of the study by participating in the data collection via face-to-face interviews.

Testing Antioxidant Activity of Pineapple (Ananas Comossus Merr.) Rinds Using UV-Vis Spectrophotometry Method

Pineapple (Ananas comossus Merr.) is one of the plants that is widespread in tropical and subtropical areas. This plant content vitamin C and antioxidant activity. This study was conducted to identify the class of secondary metabolite compounds and determine the antioxidant activity of pineapple fruit peel. Antioxidant activity testing on pineapple fruit peel was conducted using UV-Vis spectophotometric method with wavelength of 514 nm. The identification of secondary metabolite compounds showed that the methanol extract of pineapple fruit peel contains alkaloid, flavonoid, phenol, tannin and saponin compounds. Antioxidant activity of methanol extract of pineapple fruit peel carried out by DPPH (1,1-diphenyl-2-picryldhydrazyl) method shows IC50 value of 92.87 ppm with strong category, while vitamin C as a comparison has IC50 value of 9.31 ppm with very strong category. This is due to the pineapple fruit peel containing high levels of vitamin C. In addition, pineapple fruit peel contains secondary metabolites, especially flavonoids, phenols and tannins which are a class of polyphenolic compounds.

Late Quaternary hydroclimate variability in Madagascar and its connection to atmospheric circulation patterns

Large uncertainties still exist about the long-term mechanisms influencing the hydroclimate variability of southeast Africa where proxy data and model simulations indicate rainfall dipoles between subtropical and tropical areas. The topography of Madagascar, located off the southeastern coast of Africa, modulates these dipoles while its climate is influenced by the position of the Intertropical Convergence Zone (ITCZ) and the Subtropical High as well as the sea surface temperature (SST) of SW Indian Ocean. The island can thus be considered a key location for the understanding of the tropical SE African climatic variability and the interplay between atmospheric patterns. However, the scarcity of continuous records from Madagascar has made the evolution of regional late Quaternary climate and its driving mechanisms difficult to assess. Here, we present a 26-kyr record of the deuterium/hydrogen isotope ratio (δD) of biomarkers (n-alkanes) from the central eastern part of the island at Antananarivo at around 1250 m a.s.l. Preliminary summary pollen data are also presented as a comparison. The δD profiles of aquatic plant and terrestrial plant-derived n-alkanes generally exhibit similar trends implying that they all record changes in the isotope composition of source water, namely meteoric water that recharges soil and lake waters. In this tropical region, the δD variability of precipitation is mainly influenced by the amount effect reflecting the intensity of precipitation associated with the monsoon. We observe: (i) stable and wet conditions during the Last Glacial Maximum, (ii) drier conditions from 18.5 to 15 ka (ka before present) during the Heinrich Stadial 1 (iii) high humidity after 15 ka culminating at the Younger Dryas (YD), (iv) drier conditions from 11.7 ka to 8.2 ka, (v) a return to humid climate until 2.8 ka, and (vi) an arid phase followed by increased wetness after 0.9 ka, although the record is likely influenced by human-induced vegetation changes the last 1.2 ka. This climate signal is similar to other records from the Mozambique Channel but opposite to records from the East African mainland and the subtropical southern Africa, especially between 20 and 25°S. Although there is a good correspondence of our record with insolation- driven migrations of ITCZ during the LGM and the early Holocene, the dipoles are largely consistent with the modern rainfall anomaly and are best explained by the interlinked effects of the SST changes and the variability of the Mozambique Channel Trough.

Successful management of chromoblastomycosis utilizing conventional antifungal agents and imiquimod therapy

Chromoblastomycosis (CBM), a chronic fungal infection affecting the skin and subcutaneous tissues, is predominantly caused by dematiaceous fungi in tropical and subtropical areas. Characteristically, CBM presents as plaques and nodules, often leading to scarring post-healing. Besides traditional diagnostic methods such as fungal microscopy, culture, and histopathology, dermatoscopy and reflectance confocal microscopy can aid in diagnosis. The treatment of CBM is an extended and protracted process. Imiquimod, acting as an immune response modifier, boosts the host’s immune response against CBM, and controls scar hyperplasia, thereby reducing the treatment duration. We present a case of CBM in Guangdong with characteristic reflectance confocal microscopy manifestations, effectively managed through a combination of itraconazole, terbinafine, and imiquimod, shedding light on novel strategies for managing this challenging condition.

Afforestation of a floodplain system in Paraguay with eucalyptus: Effects on soil properties and nutrient stocks

The gramineous species Andropogon lateralis and Paspalum notatum dominate lowland habitats in Paraguay. These habitats include wetlands and aquifers that provide essential ecosystem services, such as soil C storage, biodiversity, water flow regulation and water quality. Large areas of these valuable natural ecosystems have been transformed into intensive agricultural systems, including sugarcane and eucalyptus plantations. The transformation potentially affects water flow and lake and stream recharge and threatens the native biodiversity of the ecoregion. The soils in these zones are characterised by high C stocks, high acidity, nutrient limitation (low cation exchange capacity and base saturation) and a sandy texture, and they may be sensitive to perturbations. This study aimed to assess the impact of eucalyptus plantations on soil properties and nutrient and C stocks in afforested lowland regions in a subtropical area and to generate information relevant to sustainable management. For this purpose, 62 eucalyptus plantations of ages between 2 and 10 years and 8 native grassland plots were selected for study. The experimental design enabled us to estimate the amounts of nutrients extracted throughout the plantation rotation and to evaluate the impacts on soil properties (at 0–40 cm depth) and on soil carbon and nutrient stocks. The eucalyptus biomass production amounted to 215 Mg ha−1 after 10 years. The significant loss of soil C, which had decreased to 40 % after a decade, was attributed to the initial soil preparation, intensive drainage and the lower input of organic remains than in the natural grasslands. The significant decreases in soil nutrient stocks (N, P, Ca, Mg, and K), reaching between 50 % and 60 % throughout the rotation, were attributed to uptake of these elements by the trees. The bulk density increased by up to 1.3 g cm−3. The data suggest that establishing eucalyptus plantations in these lowland habitats leads to soil degradation and may reduce the environmental services supplied by the ecosystems. Local authorities must develop and implement territorial land plans and silvicultural practices in order to prevent degradation of these critical ecosystems.

Effect of Foliar Feeding of Plant Growth Regulator and Nutrients on Phenological Attributes of Guava (Psidium guajava L.) cv Apple Colour

Guava, (Psidium guajava L.), small tropical tree or shrub of the family Myrtaceae, cultivated for its edible fruits. Guava trees are native to tropical America and are grown in tropical and subtropical areas worldwide. Nutrients and PGR play a crucial role in flowering and fruit production and their deficiency can significantly impact the yield, productivity, and quality of fruits. Therefore, keeping these points in view, the present investigation was carried out on a 10-year-old guava plant in a high-density plantation (3x3) at the Fruit Research Station Imaliya, Department of Horticulture, J.N.K.V.V., Jabalpur (M.P.) during the mrig-bahar season of 2022-23. The study employed a Factorial Randomised Block Design (FRBD) with 20 treatment combinations involving Plant Growth Regulators (PGR) like salicylic acid and various nutrients, replicated three times. Results indicated that the combination of salicylic acid (200 ppm) + borax (0.5%) significantly influenced several phenological parameters. This treatment resulted in the earliest flower bud initiation (18.33 days) after foliar application, the highest average number of flower buds per shoot (7.05), minimum days to 50% flowering (33.67 days), maximum average number of flowers per shoot (6.95), the highest fruit set percentage (92.18%), the highest fruit retention percentage (81.23%), and the lowest fruit drop percentage (18.77%). The application of salicylic acid at 200 ppm in conjunction with borax at 0.5% (S2 M4) followed by salicylic acid at 300 ppm with borax at 0.5% (S3 M4) demonstrated exceptional efficacy in significantly optimizing phenological parameters when compared to the control.

Phytochemicals of Alpinia zerumbet: A Review.

Alpinia zerumbet (Pers.) B.L.Burtt & R.M.Sm is a perennial plant of the Zingiberaceae family widely distributed in the subtropical and tropical areas of South America, Oceania, and Asia. Multiple plant parts of A. zerumbet have been traditionally used as medicinal sources, each with different clinical uses. These variations may arise from differences among the chemical components and/or accumulations of the active compounds in each part. Therefore, this review summarizes previous studies on the phytochemicals in A. zerumbet and reveals the similarities and differences among the chemical constituents of its multiple medicinal parts, including the leaves, rhizomes, fruits, seeds, and flowers. The results contribute to the scientific validation of the traditional understanding that A. zerumbet possesses different medicinal properties in each plant part. In addition, this review provides directions for further studies on the phytochemicals of this plant.

Adsorption of metals on aged microplastics in intensive mariculture areas: Aggravating the potential ecological risks to marine organisms

Field determination of the metal adsorption capacity of microplastics (MPs) by using a passive sampler had been done in typical subtropical mariculture area in China. The adsorption of eight metals (Fe, Mn, Cu, Zn, As, Pb, Cr and Cd) by five types of MPs (low-density polyethylene, polypropylene, polystyrene, poly(ethylene terephthalate) and poly(vinyl chloride) (PVC) was compared, including metal types, mariculture types (cage and longline culture), metal residue content in ambient environment, polymer types and particle sizes of MPs. The results showed that Cu, Zn, As, Cd, Pb and Cr in the mariculture environment were contaminated compared with the quality criteria. The concentrations of these six metals adsorbed on five MPs increased linearly with those in seawater. More enriched Cu and As in MPs in marine cage culture than in longline culture, due to the obvious endogenous pollution emissions for the artificial diets, fish medicine and disinfectants. Aged PVC with more cracks and pores showed higher metal adsorption capacity than any other polymers. MPs with a smaller size range of 50–74 μm tended to accumulate higher amounts of metals than those with a larger size range of 74–178 μm, consisting with the surface characteristics of MPs. The significant positive relationship between the concentrations of nutrients in seawater and the adsorption amounts of Cu, Zn and As on MPs implies that the eutrophication would promote their pollution. Based on the ecological risk assessment, the occurrence of MPs could aggravate the potential risk of metals to marine organisms in intensive mariculture areas. This is the first time to reveal the impacts of the adsorption of metals on aged MPs on the potential ecological risks of metals to organisms under the realistic environmental condition.

Comparative Analysis of Chloroplast Genome Variation and Evolutionary Analysis of the Endangered Species Dendrobium flexicaule and its Relative Species

Globally, the genus Dendrobium (Family: Orchidaceae) exhibits widespread distribution, predominantly occupying the tropical and subtropical areas of Asia. Although the chloroplast genomes (cpDNAs) of certain Dendrobium species have been documented, the evolutionary relationships among these species remain largely unexplored. In this pioneering investigation, a comprehensive analysis of the complete cpDNAs from Dendrobium species is presented, including Dendrobium flexicaule along with three closely related taxa (D. nobile, D. officinale, and D. huoshanense). The size of the novel complete cpDNAs ranged from 150,529 to 152,588 bp, and their cpDNA structure exhibits a unique quadrifoliate structure reminiscent of female quadrivalents, including large single copy, small single copy (SSC), and inverted repeat regions. A total of 175 simple sequence repeats were identified in the D. flexicaule cpDNA. A few pseudogenes of the NA(D)H dehydrogenase-like (NDH) genes were found in the annotated cpDNAs of the four Dendrobium species. Within the shared pseudogenes ndhF and ndhG, ndhF frequently undergoes mutations. Additionally, the phylogenetic analysis showed that D. flexicaule and D. scoriarum were close sister species. The research findings provide crucial genetic information for the molecular phylogenetic system of D. flexicaule.

Forecasting daily rainfall in a humid subtropical area: an innovative machine learning approach

ABSTRACT Hydrological modeling is one of the most complicated tasks in sustainable water resources management, particularly in terms of predicting rainfall. Predicting rainfall is critical to build a sustainable society in terms of hydropower operations, agricultural planning, and flood control. In this study, a hybrid model based on the integration of k-nearest neighbor (KNN), XGBoost (XGB), decision tree (DCT), and Random Forest (RF) has been developed and implemented for forecasting daily rainfall for the first time at Sydney airport, Australia. Daily rainfall, temperature, evaporation, and humidity have been selected as input parameters. Three statistical measurements, namely, root mean square error (RMSE), coefficient of determination (R2), mean absolute error (MAE), and Normalized Root Mean Square Error (NRMSE) have been utilized in order to check the accuracy of the proposed model. A sensitivity analysis was conducted, and the results indicated that for the purpose of prediction, the temperature, humidity, and evaporation were highly sensitive to the rainfall data. According to the results, the developed hybrid model was capable of predicting daily rainfall with high performance for both training and testing parts with RMSE = 0.124, R2 = 0.999, MAE = 0.007, NRMSE = 0.04 and RMSE = 1.246, R2 = 0.991, MAE = 0.109, NRMSE = 0.339, respectively.

Discovery of azaleatin as a potential allosteric inhibitor for dengue NS2B-NS3 protease using in vitro and in silico studies

The rise in dengue cases in tropical and sub-tropical areas has become a significant health concern. At present, there is no definitive cure for dengue fever, which underscores the importance of identifying potent inhibitors. Dengue NS2B-NS3 protease is the prime drug target due to its vital function for replication. Quercetin, a flavone, has anti-dengue virus properties but is limited by low bioavailability. Previous studies have shown that methoxy substitution in flavones improves bioavailability and metabolic stability. Azaleatin is a derivative of quercetin with a methoxy substitution at the C5 position, however its ability to inhibit dengue is unknown. In this study, azaleatin was investigated for its inhibition against dengue NS2B-NS3 protease using in vitro and in silico techniques. The fluorescence assay was used to determine the IC50 value and inhibition kinetics. The molecular interaction between azaleatin and NS2B-NS3 was studied using CB-Dock2 and AutoDock Vina. The complex’s stability was then analysed using GROMACS. Besides, the ADMETlab 2.0 was utilized to predict pharmacokinetic of the azaleatin. Results showed that azaleatin inhibits dengue NS2B-NS3 protease non-competitively with a Ki of 26.82 µg/ml and an IC50 of 38 µg/ml. Molecular docking indicated binding of the azaleatin to the allosteric pocket of NS2B-NS3 with a docking score of −8.2 kcal/mol. Azaleatin was found stable in the pocket along 100 ns, supporting its inhibitory mode. The compound has favourable pharmacokinetic profiles and conformed to Lipinski’s Rule of Five. Taken together, azaleatin inhibits NS2B-NS3 protease in a non-competitive mode, suggesting its potential as safer anti-dengue compound. Communicated by Ramaswamy H. Sarma