Dilution Effect Research Articles

Assessment of an automated titration system for batch measurements of total alkalinity

Total alkalinity (TA) is the measure of water's ability to neutralize acids. Discrete TA samples are typically measured by acid titration, with one sample processed at a time, which is tedious and time-consuming. In this study, we assessed an automated titration system for TA batch measurements that included the washing procedure between each sample analysis; and evaluated the impact of various factors on the precision of TA measurement, including the sample mass, sample salinity, temperature variation, and the dilution effect from the residual washing water. The results showed that temperature variation within ±1 °C, salinity ranging from 0 to 40, sample mass from 20 to 30 g, and the residual washing water within 2 g did not affect the precision of TA measurement (±2 μmol/kg). In addition, the automated titration system encoded with Gran calculation managed to determine the negative TA as low as −100 μmol/kg. Our study suggests that the automated titration system with an auto-sampler is capable of high-precision TA batch measurements.

Impact of legacy and unintentionally produced polychlorinated biphenyls (PCBs) in effluents from two wastewater treatment plants in rivers near Barcelona, Spain

Polychlorinated biphenyls (PCBs) are a family of 209 congeners listed as Persistent Organic Pollutants in the Stockholm Convention. Although there has been a lot of focus on those congeners present in the Aroclor or Clophen technical mixtures commercialized in the past (legacy PCBs), other industrial processes such as paint and pigment production can generate other congeners as byproducts (Unintentionally Produced PCBs or UP-PCBs). The present study focuses on the analysis of 72 PCB congeners (including 42 UP-PCBs) in the two major rivers surrounding the city of Barcelona -Llobregat and Besós rivers-, and their levels in two wastewater treatment plants during the production of effluents and reclaimed water. It was observed that WWTP can efficiently remove PCBs from untreated water during sludge production where concentrations are six orders of magnitude higher than in water (in the ng g−1 and pg L−1 ranges, respectively). Although PCB levels in the effluent and reclaimed water replenishing the rivers are not negligible, these do not significantly increase the concentrations already found in the studied rivers, and in most cases PCB concentrations in river water are reduced after merging with the reclaimed water due to dilution effect. The presence of UP-PCB-11 (not present in the Aroclor technical mixtures) in the analyzed water and sludge samples is significant (ranging from 22 to 25 % of the total PCB amount in the Besós river), being often one of the most abundant PCB congeners.

Effect of Polystyrene Microplastics on Pb(II) Adsorption onto a Loessial Soil (Sierozem) and Its Mechanism.

Microplastics (MPs) have received significant attention recently. However, their influence on soil heavy metal adsorption remains unclear. The effect of polystyrene (PS) MPs on the adsorption of Pb(II) onto a loessial soil (sierozem) was studied by batch experiments in single soil (S), soil with 1 mm PS (S-PS1), and soil with 100 μm PS (S-PS100) systems. The mechanisms of Pb(II) adsorption reduction were investigated. The adsorption of Pb(II) reached equilibrium within 12 h, and the pseudo-second-order model fitted the adsorption processes best. The Langmuir adsorption model provided a better fit to the isotherms, compared to the Freundlich one. The presence of PS decreased the level of adsorption of Pb(II). Larger PS particle size, dose, and fulvic acid (FA) concentration inhibited Pb(II) adsorption onto the soil. The solution pH value showed a positive correlation with the adsorption amount. The adsorption amounts (q e) of Pb(II) in binary metal systems (Cu-Pb and Cd-Pb) were lower than those in single Pb systems, indicating the competitive adsorption among the ions. The adsorption amount presented a trend of S > S-PS100 > S-PS1. The primary mechanism on which PS reduced the adsorption of Pb(II) was the "dilution effect" of MPs. Conclusively, the presence of MPs might elevate the availability of heavy metals by reducing the soil's adsorption capacity for them and then amplifying the risk of heavy metal contamination and migration.

CO formation characteristics in a centrally staged swirl combustor

Based on a validated numerical simulation methodology, this study focused on a centrally staged swirl combustor to investigate the combustion flow field inside the chamber under typical operating conditions. The CO formation characteristics of each region in the combustor were analyzed. In terms of elementary reactions, this study analyzed crucial reaction pathways contributing to CO formation in distinct regions utilizing the eddy dissipation concept model. Results reveal the occurrence of CO formation in the flame front and its rapid oxidation to form CO2 in the post-flame zone. CO2 partially dissociates into CO at high temperatures. Furthermore, air film quenching substantially impacts CO formation and emission, and air film greatly affects CO oxidation more than its formation. Local cooling and dilution effects from the air film contribute to the freezing of CO oxidation reactions. Therefore, a substantial quantity of CO remains unreacted, leading to increased CO emissions at the combustion chamber outlet.

Facilitated core-edge integration through divertor nitrogen seeding in the HL-2A tokamak

A divertor detachment with sustainable high-performance plasmas has been achieved through divertor nitrogen seeding in the HL-2A tokamak. The closed divertor structure facilitates achieving high divertor neutral pressure due to its efficient particle containment effect as demonstrated by both experimental and SOLPS simulation results, which aids in achieving the divertor detachment. The radiative divertor is conducive to high-frequency small edge localized modes (ELMs) operation, characterized by a reduced pedestal ion temperature gradient ∇Ti and the enhanced electron density gradient ∇ne . The presence of minority nitrogen at the edge plasma, which results from the divertor nitrogen seeding, contributes to the increase of ion temperature Ti in the confinement region by suppressing the turbulence through the impurity dilution effect and E×B shear. The increased ion temperature Ti and electron density ne compensate the energy loss resulting from the increased edge radiation during detachment, which contributes to the confinement sustainment combined with reduced pedestal energy loss caused by small ELMs. This work advances our understanding of the fundamental physics governing closed divertor detachment with sustainable high-performance plasmas through divertor nitrogen seeding.

Elucidating the role of recycled concrete powder in low-carbon ultra-high performance concrete (UHPC): Multi-performance evaluation

Reusing recycled powder as an alternative binder for ultra-high performance concrete (UHPC) offers a highly value-added approach to recycling concrete waste. This study shows the multi-performance evaluation of low-carbon UHPC containing recycled powder as a substitution of cement and silica fume. Recycled powder, which includes recycled concrete powder (RCP) and recycled paste powder (RPP), contains massive SiO2, CaCO3 and hydration products. Substituting recycled powder for cement reduces the cumulative hydration heat per gram binder, while increasing the cumulative hydration heat per gram cement of UHPC. Replacing high-volume cement and silica fume with recycled powder negatively impacts the micro-characteristics, increasing the drying shrinkage and transport properties. When using recycled powder as cement replacement, incorporating a moderate dosage of recycled powder has negligible impact and can even confer some beneficial effects on the mechanical strength. Substituting recycled powder for high-volume cement reduces the mechanical strength, yet the blended UHPC retains good mechanical strength. The compressive strength of UHPC containing RCP as 0 %, 30 %, 50 % and 70 % of cement is 157.6 MPa, 154.6 MPa, 145.0 MPa and 129.9 MPa, respectively. Due to its good dilution and active effects, the replacement of cement with recycled powder causes a significant increase in compressive strength per unit cement, and the mix of 70 % RCP increases the compressive strength per unit cement by 174.7 %. Besides, incorporating recycled powder as silica fume replacement causes a limited reduction in the mechanical strength of blended UHPC. The RCP-UHPC generally has better micro-macro properties than the RPP-UHPC. By optimizing recycled powder type and replacement rate, UHPC with excellent micro-macro performance can be achieved.

Microplastic dilemma: Assessing the unexpected trade-offs between biodegradable and non-biodegradable forms on plant health, cadmium uptake, and sediment microbial ecology

Despite extensive substitution of biodegradable plastics (BPs) for conventional plastics (CPs), research on their environmental ecological consequences as microplastics (MPs) is scarce. This study aimed to fill this gap by investigating the impacts of six prototypical MPs (categorized into BMPs and CMPs) on plant growth, cadmium (Cd) translocation, and bacterial communities in contaminated sediments. Results showed both BMPs and CMPs hindered plant development; yet interestingly, BMPs provoked more pronounced physiological and biochemical changes alongside increased oxidative stress due to reactive oxygen species accumulation. Notably, most MP types promoted the absorption of Cd by plant roots potentially via a “dilution effect”. BMPs also induced larger shifts in soil microbial metabolic functions compared to CMPs. Ramlibacter was identified as a key biomarker distinguishing BMPs from CMPs, with link to multiple N metabolic pathways and N assimilation. This study offers novel insights into intricate biochemical mechanisms and environmental chemistry behaviors underpinning MP-Cd interactions within the plant-microbe-sediment system, emphasizing BMPs’ higher potential ecological risks based on their significant effects on plant health and microbial ecology. This work contributes to enhancing the comprehensive understanding of their ecological implications and potential threats to environmental security.

The dominant influence of muddy bottom currents on organic-rich fine-grained sedimentary rocks: The lower Congo Basin, west Africa

The Madingo Formation in the Lower Congo Basin (LCB) of West Africa is a fine-grained strata, which is considered to be the most promising source interval during the drift stage. Despite the extensive studies of the internal sedimentary characteristics of the Lower Mading Formation (LMF), muddy bottom currents have not been previously identified in this area. Extensive seismic (2D and 3D data), wire - line measurements and cutting samples in the LCB offer a unique opportunity to study the influence of muddy bottom currents depositional system on organic matter, and related depositional environment of the region and its depositional model of organic rich fine-grained strata. This study aims to unravel the influence of muddy bottom currents on organic matter enrichment within the LMF and build a depositional model. In combination with drilling and thin sections analysis, the M-1 member suggests the initiation and cessation of muddy bottom currents. Utilizing 3D seismic data inversion techniques, geochemical analysis, and sedimentological assessment, we studied the effect of muddy bottom currents on organic matter enrichment from the perspectives of paleoproductivity, preservation conditions, terrigenous input, and total organic carbon (TOC) distribution. Results show that muddy bottom currents have a significant impact on the redistribution of shallow water shelf sediments. They promote the transportation of nutrients and organic matter to deep water shelves, improving paleoproductivity. Most notably, terrigenous input is a key factor affecting organic matter distribution, resulting in dilution effects in deep water shelf bottom current influence areas, but conducive to the preservation of deep organic matter in low-lying areas of shallow water shelf. Muddy bottom currents have a weaker influence on the preservation environment of deep water shelves, but they have a significant effect on redox indicators (eg. U/Th, Ni/Co, V/Cr). Specifically, they reduce the enrichment in particulate elements. We established the depositional models of organic-rich fine-grained sedimentary rocks for the M-1 and M-2 members in LCB. These insights not only provide practical depositional models for marine sources rocks in the LCB, but also improves the general understanding of marine organic matter accumulation in muddy bottom currents environments. Furthermore, they serve as a reference for the study of organic-rich fine-grained sedimentary rocks in similar basins.

Detection of Multiple Human Viruses, including Mpox, Using a Wastewater Surveillance Approach in Brazil.

Sewage surveillance can be used as an effective complementary tool for detecting pathogens in local communities, providing insights into emerging threats and aiding in the monitoring of outbreaks. In this study using qPCR and whole genomic sewage surveillance, we detected the Mpox virus along with other viruses, in municipal and hospital wastewaters in Belo Horizonte, Brazil over a 9-month period (from July 2022 until March 2023). MPXV DNA detection rates varied in our study, with 19.6% (11 out of 56 samples) detected through the hybrid capture method of whole-genome sequencing and 20% (12 out of 60 samples) through qPCR. In hospital wastewaters, the detection rate was higher, at 40% (12 out of 30 samples) compared to 13.3% (4 out of 30 samples) in municipal wastewaters. This variation could be attributed to the relatively low number of MPXV cases reported in the city, which ranged from 106 to 341 cases during the study period, and the dilution effects, given that each of the two wastewater treatment plants (WWTP) investigated serves approximately 1.1 million inhabitants. Additionally, nine other virus families were identified in both hospitals and municipal wastewaters, including Adenoviridade, Astroviridae, Caliciviridae, Picornaviridade, Polyomaviridae, Coronaviridae (which includes SARS-CoV-2), Herspesviridae, Papillomaviridae and Flaviviridae (notably including Dengue). These findings underscore the potential of genomic sewage surveillance as a robust public health tool for monitoring a wide range of viruses circulating in both community and hospitals environments, including MPXV.

A study of laser-remelted flame-sprayed NiCrBSi/W composite coatings: the influence of thermal diffusivity

The article presents research results on the microstructure of laser-remelted NiCrBSi coatings deposited with flame spraying. Two types of coating powders were used. Commercial Metco 15E powder is strengthened with chromium-based carbide and boride phases based on a eutectic form of Ni(Cr) solid solution matrix with borides and Ni silicides. The second powder was also Metco 15E but with the addition of 50 mass% metallic tungsten granules. In both cases, identical parameters of the flame spraying and laser melting processes were used. It was found that introducing tungsten significantly changes the morphology of the coating. This applies to the size of the heat-affected zone, its microstructural nature (grain growth), and the dilution effect. These elements influenced the level of hardness obtained, which was lower in the case of the modified coating. At the same time, however, the modified coating was characterised by a stable microhardness distribution in the cross section, especially in connection with the substrate material. This indicates a strong tendency of tungsten to annihilate the dilution effect and inhibits the decrease in the hardness of the carbide and boride phases associated with the increase in iron content. The factor responsible for the described effects is a significant difference in the thermal diffusivity of the materials used to produce the coatings. This size significantly impacts the scale of the created heat-affected zone and directly affects the mixing effect.

Numerical investigation of soot formation in methane/n-heptane laminar diffusion flame doped with hydrogen at elevated pressure

The addition of hydrogen in a dual-fuel mode based on natural gas and diesel offers great potential for improving engine efficiency and reducing emissions. Therefore, detailed numerical simulations have been used to explore the effects of soot formation characteristics of natural gas-diesel dual-fuel engines doped by hydrogen at elevated pressure. Numerical simulations are compared with available experimental data, the effects of H2 addition on soot formation in laminar CH4 + n-heptane, H2 + CH4 + n-heptane, FH2 + CH4 + n-heptane diffusion flames at 2, 4, 6 and 8 atm are simulated, FH2 is added to separate the H2 chemical effects. The results show that the dilution and thermal effects of H2 inhibit soot formation, while the chemical effects of H2 promote soot formation under different pressures. The addition of H2 increases the concentration of H and OH radicals, which promotes the formation of C2H2 and benzene (A1). By simplifying the reaction path and analyzing the production rate of A1, the mechanism of H2 addition to promote A1 formation is illustrated. The concentrations of polycyclic aromatic hydrocarbon (PAH) pyrene (A4), benzo(ghi)fluoranthene (BGHIF) and benzo(a)pyrene (BAPYR) are inhibited at higher pressures that result in lower inception and condensation rates. Therefore, the increase of hydrogen abstraction acetylene addition (HACA) rate is the main reason for the increase of soot formation under chemical effects. While the O2 oxidation rate decreases and the OH oxidation rate increases, that is due to the decrease of O2 concentration and the increase of OH concentration in the soot formation area under chemical effects.

The role of ruminant urine and faeces in the recycling of nutrients by forages

This study addresses the effect of using animal excreta on the nutritional content of forages, focusing on macro- and micro-element concentrations (nitrogen; N, phosphorus; P, sulphur; S, copper; Cu, zinc; Zn, manganese; Mn, selenium; Se) from animal feed to excreta, soil, and plants. Data were collected from pot and field trials using separate applications of sheep or cattle urine and faeces. Key findings indicate that soil organic carbon (SOC) and the type of excreta significantly influences nutrient uptake by forages, with varied responses among the seven elements defined above. Although urine contributes fewer micronutrients compared to faeces (as applied at a natural volume/mass basis, respectively), it notably improves forage yield and micronutrient accumulation, thus potentially delivering positive consequences at the farm level regarding economic performance and soil fertility when swards upon clayey soil types receive said urine in temperate agro-climatic regions (i.e., South West England in the current context). In contrast, faeces application in isolation hinders Se and Mn uptake, once again potentially delivering unintended consequences such as micronutrient deficiencies in areas of high faeces deposition. As it is unlikely that (b)ovine grazing fields will receive either urine or faeces in isolation, we also explored combined applications of both excreta types which demonstrates synergistic effects on N, Cu, and Zn uptake, with either synergistic or dilution effects being observed for P and S, depending largely on SOC levels. Additionally, interactions between excreta types can result in dilution or antagonistic effects on Mn and Se uptake. Notably, high SOC combined with faeces reduces Mn and Se in forages, raising concerns for grazed ruminant systems under certain biotic situations, e.g., due to insufficient soil Se levels typically observed in UK pastures for livestock growth. These findings underscore the importance of considering SOC and excreta nutritional composition when designing forage management to optimize nutrient uptake. It should be noted that these findings have potential ramifications for broader studies of sustainable agriculture through system-scale analyses, as the granularity of results reported herein elucidate gaps in knowledge which could affect, both positively and negatively, the interpretation of model-based environmental impact assessments of cattle and sheep production (e.g., in the case of increased yields [beneficial] or the requirement of additional synthetic supplementation [detrimental]).

Capturing the dilution effect of risk‐based grouping with application to COVID‐19 screening

AbstractWe investigate the problem of screening a large population for an infectious disease (i.e., classifying subjects as positive or negative) using group testing while considering important test and population‐level characteristics. Group testing, in which multiple samples are pooled together into a master sample and tested simultaneously, has the potential to significantly expand screening efforts, and, owing to the COVID‐19 pandemic, the topic has seen a surge of interest recently. In this paper, we construct optimal group testing designs that consider a heterogeneous population (i.e., with subject‐specific risk), imperfect tests, and while also modeling the dilution effect of grouping (a phenomenon in which the test accuracy of the master sample is affected by the concentration of the virus in the pool), which is often ignored in the literature. We conduct an exhaustive analysis under both a general dilution function and a specific (yet still calibratable) form of the dilution function. Our analytical results of the resulting challenging optimization problems unveil key structural properties that hold in an optimal solution, which we utilize to construct efficient solution schemes. We complement the analysis with two case studies, one on the screening of blood for the Hepatitis B Virus and the other on the screening of subjects for COVID‐19. Our results reveal significant benefits over current practices, individual testing, as well as prior studies that ignore the dilution effect. Such results underscore the importance of incorporating both test and population‐level characteristics into the modeling framework.

Strong and consistent effects of waterbird composition on HPAI H5 occurrences across Europe.

Since 2014, highly pathogenic avian influenza (HPAI) H5 viruses of clade 2.3.4.4 have been dominating the outbreaks across Europe, causing massive deaths among poultry and wild birds. However, the factors shaping these broad-scale outbreak patterns, especially those related to waterbird community composition, remain unclear. In particular, we do not know whether these risk factors differ from those of other H5 clades. Addressing this knowledge gap is important for predicting and preventing future HPAI outbreaks. Using extensive waterbird survey datasets from about 6883 sites, we here explored the effect of waterbird community composition on HPAI H5Nx (clade 2.3.4.4) spatial patterns in the 2016/2017 and 2020/2021 epidemics in Europe, and compared it with the 2005/2006 HPAI H5N1 (clade 2.2) epidemic. We showed that HPAI H5 occurrences in wild birds in the three epidemics were strongly associated with very similar waterbird community attributes, which suggested that, in nature, similar interspecific transmission processes operate between the HPAI H5 subtypes or clades. Importantly, community phylogenetic diversity consistently showed a negative association with H5 occurrence in all three epidemics, suggesting a dilution effect of phylogenetic diversity. In contrast, waterbird community variables showed much weaker associations with HPAI H5Nx occurrence in poultry. Our results demonstrate that models based on previous epidemics can predict future HPAI H5 patterns in wild birds, implying that it is important to include waterbird community factors in future HPAI studies to predict outbreaks and improve surveillance activities.

Effect of Hydrogen Addition on Soot Reduction in Diffusion Flames

This study explores the effects of hydrogen addition on soot reduction in methane-air diffusion flames, employing computational analysis coupled with chemical equilibrium and k-epsilon combustion turbulence models. By varying the fuel mixture with hydrogen mass percentages ranging from 0% to 11%, alterations in flame behaviour were observed. Results revealed a notable increase in maximum flame temperature at 1.3% hydrogen addition, attributed to enhance combustion efficiency, while subsequent additions led to temperature decrements due to dilution effects. Concurrently, soot production exhibited a general decrease, with reductions quantified up to 96.7% compared to baseline conditions, primarily due to improved oxidation and decreased carbon content. Additionally, the position of maximum flame temperature and soot mass fraction shifted along the axial direction owing to hydrogen's higher flammability compared to methane-air diffusion. These findings offer insights into optimizing flame characteristics for reduced particulate matter emissions, emphasizing the potential of hydrogen addition in mitigating soot formation in diffusion flames.

Intention to treat and per protocol analyses: differences and similarities

Randomized trials can take more explanatory or more pragmatic approaches. Pragmatic studies, conducted closer to real-world conditions, assess treatment effectiveness while considering factors like protocol adherence. In these studies, intention-to-treat (ITT) analysis is fundamental, comparing outcomes regardless of the actual treatment received. Explanatory trials, conducted closer to optimal conditions, evaluate treatment efficacy, commonly with a per protocol (PP) analysis, which includes only outcomes from adherent participants. ITT and PP are strategies used in the conception, design, conduct (protocol execution), analysis, and interpretation of trials. Each serves distinct objectives. While both can be valid, when bias is controlled, and complementary, each has its own limitations. By excluding nonadherent participants, PP analyses can lose the benefits of randomization, resulting in group differences in factors (influencing adherence and outcomes) that were present at baseline. Additionally, clinical and social factors affecting adherence can also operate during follow-up, that is, after randomization. Therefore, incomplete adherence may introduce postrandomization confounding. Conversely, ITT analysis, including all participants regardless of adherence, may dilute treatment effects. Moreover, varying adherence levels could limit the applicability of ITT findings in settings with diverse adherence patterns. Both ITT and PP analyses can be affected by selection bias due to differential losses and nonresponse (ie, missing data) during follow-up. Combining high-quality and comprehensive data with advanced statistical methods, known as g-methods, like inverse probability weighting, may help address postrandomization confounding in PP analysis as well as selection bias in both ITT and PP analyses.

Waste glass powder as a high temperature stabilizer in blended oil well cement pastes: Hydration, microstructure and mechanical properties

Recycling waste glass for diversified utilization has received increasing attention in recent years. This work aimed to reuse waste glass powder (GP) as a high temperature stabilizer to replace silica flour (SF) in blended G class oil well cement (GOWC) pastes. Blended pastes containing 40 % and 66.7 % GP were prepared and compared to pure GOWC paste and blended paste containing 40 % SF commonly used in the oil industry. Under simulated field conditions in a steam injection well, these pastes were cured at 50 °C for seven days, followed by three rounds of thermal cycling curing at high temperature and high pressure (HTHP, 300 °C/13 MPa) conditions. The effects of GP on the hydration kinetics, hydration products, microstructure, and mechanical properties of hardened pastes were evaluated. The results demonstrated that the addition of GP or SF reduced the compressive strength of the pastes at 50 °C due to dilution effect. Compared with SF, GP exhibited higher pozzolanic activity, prolonged the induction period, and promoted the formation of more C-(N)-S-H gels with lower Ca/Si ratios, which led to an increase in the gel pores content of the matrix and partially compensated for the loss of compressive strength due to the dilution effect. Additionally, due to the pozzolanic reaction of GP, the content of CH in the matrix decreased and its crystal size became smaller. After three rounds of thermal cycling curing, the incorporation of GP significantly increased the compressive strength of the hardened pastes. The compressive strengths of the hardened pastes with 40 % and 66.7 % GP were 20.33 MPa and 22.25 MPa, respectively, which were 7.62 % and 17.79 % higher than those of the hardened paste containing 40 % SF. In addition, the compressive strengths of hardened pastes containing 40 % and 66.7 % GP after three rounds of thermal cycling curing decreased by 22.49 % and 5.52 %, respectively, compared to the pastes at the low-temperature stage, while that of the pure GOWC pastes decreased by 83.8 %. Characterization analyses indicated that GP could further reduce the Ca/Si ratio of the system, modulate the crystallization of the gels at high temperatures, and generate foshagite or xonotlite phases with high polymerization structure and thermal stability, instead of reinhardbraunsite. These products effectively refined pore structure and enhanced microstructure densification. Furthermore, the precipitation of Na+ ions during hydration did not affect the microstructure of the matrix. This study offers some guidelines for recycling waste glass, conserving raw materials, and producing sustainable blended cement pastes.

Mosquito (Diptera: Culicidae) diversity and arbovirus detection across an urban and agricultural landscape

Fragmented landscapes in Mexico, characterized by a mix of agricultural, urban, and native vegetation cover, presents unique ecological characteristics that shape the mosquito community composition and mosquito-borne diseases. The extent to which landscape influences mosquito populations and mosquito-borne diseases is still poorly understood. This work assessed the effect of landscape metrics -agriculture, urban, and native vegetation cover- on mosquito diversity and arbovirus presence in fragmented tropical deciduous forests in Central Mexico during 2021. Among the 21 mosquito species across six genera we identified, Culex quinquefasciatus was the most prevalent species, followed by Aedes aegypti, Ae. albopictus, and Ae. epactius. Notably, areas with denser native vegetation cover displayed higher mosquito species richness, which could have an impact on phenomena such as the dilution effect. Zika and dengue virus were detected in 85% of captured species, with first reports of DENV in several Aedes species and ZIKV in multiple Aedes and Culex species. These findings underscore the necessity of expanding arbovirus surveillance beyond Ae. aegypti and advocate for a deeper understanding of vector ecology in fragmented landscapes to adequately address public health strategies.

Efficacy and safety of subcutaneous immunotherapy with polymerized allergen mixtures in polyallergic patients – ARES observational study

ABSTRACT Background Administration of allergen mixtures of many components comprises the most common approach for American allergists regarding the management of polyallergic patients. European allergists, however, are more reluctant to this type of treatment due to the potential drawbacks of mixing extracts. Research design and methods To assess the efficacy and safety of subcutaneous immunotherapy (SCIT) with polymerized allergen mixtures without dilutional effect in polyallergic patients. This observational, prospective, multicenter study included patients (between 5 and 60 years) with respiratory allergic diseases that had been prescribed with SCIT with mixtures of two pollen or mite extracts. Changes in Symptoms and Medication Score (SMS) and in rhinitis quality of life questionnaire (RQLQ), subjective clinical improvement, treatment satisfaction and tolerability were assessed after the 1-year treatment. Results A total of 115 patients were included in the assessment. Mean global SMS decreased from 3.5 (SD = 1.1) to 1.6 (SD = 1.2) points, with a mean absolute reduction of 1.6 (SD = 1.3) points in the RQLQ score (p < 0.001, Wilcoxon test). General subjective clinical improvements and a good treatment satisfaction and tolerability were observed. Conclusion SCIT with polymerized allergen mixtures from either pollen or mite extracts proved to be an effective and safe treatment option for polyallergic patients suffering from allergic respiratory diseases.

Spatiotemporal Dynamics of Carbon and Nitrogen in Subtropical Urban Streams (Santo André, SP, Brazil)

Urban sprawl poses a significant threat to urban stream water quality due to impermeabilization, reduced vegetation cover, and the release of diffuse pollutants. This study evaluates water quality in seven catchments in Santo André, SP, considering seasonality. Nutrient concentrations and in situ measurements were taken during both dry and rainy seasons. Comparisons were made using Kruskal–Wallis and Mann–Whitney tests. Streams showed significant differences in relation to water quality parameters. The Carapetuba, Jundiaí, and Apiaí streams were most adversely affected, underscoring the need for urgent water quality intervention (water conductivity above 500 μS/cm, dissolved oxygen below 2 mg/L, total dissolved carbon above 50 mg/L, and total dissolved nitrogen above 25 mg/L). Significant differences were observed across seasons. The dry season showed elevated temperatures (above 25 °C) and increased total dissolved carbon (above 50 mg/L) and nitrogen concentrations (above 30 mg/L), indicating reduced dilution effects from rainfall and heightened organic contamination. Conversely, the wet season demonstrated lower nutrient concentrations, emphasizing seasonal dynamics. Sustained, long-term monitoring of urban streams in Santo André and the implementation of sewage collection and treatment in irregular settlements are recommended. These measures are essential to mitigate the adverse impacts of urban expansion on water quality.