Cycle Activation Research Articles

Application of Learning Media " Tree Chart" to Improve Student Learning Outcomes for Tarikh Islam Lesson class 3 at Darussalam Modern Islamic Boarding School Gontor Ponorogo

One of the subject matter contained in Islamic education is Tarikh Islam lessons. Tarikh Islam are one of the required lessons for students to be taught at Darussalam Modern Islamic Boarding School, which is lesson learns about Islamic history including the story of Rasulullah, Khulafaur Rashidin, Companions of Rasulullah and others. In teaching and learning activities, media is one of the important factors in learning. In view of the scores obtained by grade 3 H students in Islamic date lessons, there are 20 out of 37 students or 53% of students who get scores below the passing score standard, it is due to the lack of teachers in providing innovation in learning activities so that students become bored and do not pay attention to the lessons taught. And one of the innovations that can be used is with (Tree Chart) media learning. This study aims to, improve student activeness and learning outcomes in Islamic date subjects Class 3 H at at Darussalam Modern Islamic Boarding School by using Tree Chart learning media. This type of research is Classroom Action Research. In this study, researchers as teaching teachers and assisted by an Observer who supervises the condition of students. This research consists of the first cycle and the second cycle which consists of: Planning, Implementation, Observation, and Reflection. Data collection techniques and tools in this study are using descriptive analysis techniques on data in the form of documentation of student learning outcomes, observation sheets and test results The results of this study show that (1) the application of tree chart learning media can increase student activity. With the presentation value of student activeness in the first cycle which reached 61.37% and increased in the second cycle which reached 84.12% with the presntase there was a difference between the first and second cycles which reached 22.75%. (2) The application of tree chart learning media can improve student learning outcomes. The percentage in the first cycle of students who completed learning was 22 students out of 37 students or reached 59.45% with an average score of 5.91 and in the second cycle as many as 37 students or reached 100% with an average score of 7.78. With the explanation above, it can be concluded that tree chart learning media can increase student activeness and learning outcomes. Keywords: Student Activeness, Learning Outcomes, Tarikh Islam Lessons, Tree Chart Learning Media

Improving Socio-Emotional Skilss Through Project Method in Islamic Elementary School Student

The purpose of this study is to improve the social emotional of group B children at RA Alkhoeriyah Rajadesa, Ciamis Regency through watermelon seed planting activities using the project method. The project method is one way that can be used in teaching to train children's ability to solve problems in everyday life and can move children to work together with other children where each part of the work is individual or in small groups to achieve shared goals. The research method in this article uses the classroom action research method with the research subjects being teachers and students of group B RA Alkhoeriyah consisting of 12 children, 4 boys and 5 girls. From the data on melon seed planting activities in cycle I, it was found that 6 students or 50.00% of the total children in group B received the MB category, 4 students or 33.34% of the total children in group B received the BSH category, while there were still 2 children receiving the BB category. Meanwhile, from the data of cycle II actions, it was found that 4 children or 33.34% of the total children in the class received the BSB category, 6 children or 50.00% of the total children in the class received the BSH category, while 2 students received the MB category, with a percentage value of 16.67%.

Global distribution pattern of soil phosphorus-cycling microbes under the influence of human activities.

Human activities have profoundly altered the Earth's phosphorus (P) cycling process and its associated microbial communities, yet their global distribution pattern and response to human influences remain unclear. Here, we estimated the abundances of P-cycling genes from 3321 global soil metagenomic samples and mapped the global distribution of five key P-cycling processes, that is, organic phosphoester hydrolysis, inorganic phosphorus solubilization, two-component system, phosphotransferase system, and transporters. Structural equation modeling and random forest analysis were employed to assess the impact of anthropogenic and environmental factors on the abundance of P-cycling genes. Our findings suggest that although less significant than the climate and soil profile, human-related factors, such as economic activities and population, are important drivers for the variations in P-cycling gene abundance. Notably, the gene abundances were increased parallel to the extent of human intervention, but generally at low and moderate levels of human activities. Furthermore, we identified critical genera, such as Pseudomonas and Lysobacter, which were sensitive to the changes in human activities. This study provides insights into the responses of P-cycling microbes to human activities at a global scale, enhancing our understanding of soil microbial P cycling and underscoring the importance of sustainable human activities in the Earth's biogeochemical cycle.

Characterization of Intrinsically Disordered Proteins in Healthy and Diseased States by Nuclear Magnetic Resonance.

Intrinsically Disordered Proteins (IDPs) are active in different cellular procedures like ordered assembly of chromatin and ribosomes, interaction with membrane, protein, and ligand binding, molecular recognition, binding, and transportation via nuclear pores, microfilaments and microtubules process and disassembly, protein functions, RNA chaperone, and nucleic acid binding, modulation of the central dogma, cell cycle, and other cellular activities, post-translational qualification and substitute splicing, and flexible entropic linker and management of signaling pathways. The intrinsic disorder is a precise structural characteristic that permits IDPs/IDPRs to be involved in both one-to-many and many-to-one signaling. IDPs/IDPRs also exert some dynamical and structural ordering, being much less constrained in their activities than folded proteins. Nuclear magnetic resonance (NMR) spectroscopy is a major technique for the characterization of IDPs, and it can be used for dynamic and structural studies of IDPs. This review was carried out to discuss intrinsically disordered proteins and their different goals, as well as the importance and effectiveness of NMR in characterizing intrinsically disordered proteins in healthy and diseased states.

Soil physicochemical and microbial properties affect nitrogen cycling in technogenically transformed coal dump soils

Mining industrial sectors deteriorate local and regional environmental quality, contributing to global ecosystem contamination. The activities of microorganisms and enzymes involved in nitrogen cycling processes were investigated in coal dump soils that had undergone technogenic transformations and reclamation. Compared to the background uncontaminated soil, the heavy metal concentrations increased to high contamination levels (the contents of mobile forms of Zn, Ni, and Cu were 66.9; 35.6; 12.9 mg/kg, respectively), salinity increased to 0.1–2.41 %. The activities of nitrification and denitrification as well as the abundance of ammonifiers reduced due to high concentrations of mobile forms, the presence of coal particles, and the salinity of soil samples. The urease activity decreased due to reduced content of soluble organic matter in disturbed soils (2.3 times lower than the background soils). Mechanical reclamation leads to a 4-fold decrease in soil toxicity levels; however, it does not enhance nitrogen cycling activity. The activity of nitrification and urease decreased by >4 times as compared to the soil of the protected area. Microbial community composition of coal mine soils was similar to that of undisturbed soil. Nitrifiers in coal mine soil were represented by the genera Nitrososphaera, Candidatus Nitrosocosmicus, Nitrosospira, Nitrosomonas, Nitrosococcus, Nitrospira, Nitrobacter. The results indicated that the disruption of nitrification process led to low nitrate content in technogenically transformed coal dump soils.

Streptomyces-Secreted Fluvirucin B6 as a Potential Bio-Fungicide for Managing Banana Fusarium Wilt and Mycotoxins and Modulating the Soil Microbial Community Structure.

Banana Fusarium wilt caused by Fusarium oxysporum f. sp. cubense (Foc TR4) is the most destructive soil-borne fungal disease. Until now, there has been a lack of effective measures to control the disease. It is urgent to explore biocontrol agents to control Foc TR4 and the secretion of mycotoxin. In this study, fluvirucin B6 was screened from Streptomyces solisilvae using an activity-guided method. Fluvirucin B6 exhibited strong antifungal activity against Foc TR4 (0.084 mM of EC50 value) and significantly inhibited mycelial growth and spore germination. Further studies demonstrated that fluvirucin B6 could cause the functional loss of mitochondria, the disorder of metabolism of Foc TR4 cells, and the decrease of enzyme activities in the tricarboxylic acid cycle and electron transport chain, ultimately inhibiting mycotoxin metabolism. In a pot experiment, the application of fluvirucin B6 significantly decreased the incidence of banana Fusarium wilt and the amount of Foc TR4 and controlled fungal toxins in the soil. Additionally, fluvirucin B6 could positively regulate the changes in the structure of the banana rhizosphere microbial community, significantly enriching beneficial microbes associated with disease resistance. In summary, this study identifies fluvirucin B6, which plays versatile roles in managing fungal diseases and mycotoxins.

ALTMAN: A Novel Method for Cell Cycle Analysis.

Accurate analysis of S-phase fraction is crucial for the assessment of cell proliferation levels, tumor malignancy and prognostic effects of treatment. Most of the currently developed methods for S-phase cell analysis rely on flow cytometric analysis of DNA content determination. However, the lack of standardized procedures for sample analysis and interpretation of cell cycle fitting graphs poses a significant limitation in clinical practice for utilizing flow cytometry to measure the cell cycle based on DNA content. Herein, we developed an approach for analyzing S-phase cells based on telomerase activity determination. Briefly, this approach distinguishes S-phase cells in cell populations via direct fluorescence tracking of telomerase activity within individual cells. The dynamic analysis of telomerase activity in different cell cycles was made possible by the ALTMAN strategy developed in our previous studies, which has been successfully employed to distinguish S-phase cells in cultured cells. This method offers a novel avenue for the assessment of cell cycle status and the evaluation of the proliferation status of tumor cells and the prognosis effect of tumor patients via analyzing the differences in telomerase activity during different cell cycle processes.

Metformin Restrains the Proliferation of CD4+ T Lymphocytes by Inducing Cell Cycle Arrest in Normo- and Hyperglycemic Conditions.

CD4+ T lymphocytes play a key role in the modulation of the immune response by orchestrating both effector and regulatory functions. The effect of metformin on the immunometabolism of CD4+ T lymphocytes has been scarcely studied, and its impact under high glucose conditions, particularly concerning effector responses and glucose metabolism, remains unknown. This study aims to evaluate the effect of metformin on the modulation of the effector functions and glucose metabolism of CD4+ T lymphocytes under normo- and hyperglycemic conditions. CD4+ T lymphocytes, obtained from peripheral blood from healthy volunteers, were anti-CD3/CD28-activated and cultured for 4 days with three concentrations of metformin (0.1 mM, 1 mM, and 5 mM) under normoglycemic (5.5 mM) and hyperglycemic (25 mM) conditions. Effector functions such as proliferation, cell count, cell cycle analysis, activation markers and cytokine secretion were analyzed by flow cytometry. Glucose uptake was determined using the 2-NBDG assay, and levels of glucose, lactate, and phosphofructokinase (PFK) activity were assessed by colorimetric assays. Metformin at 5 mM restrained the cell counts and proliferation of CD4+ T lymphocytes by arresting the cell cycle in the S/G2 phase at the beginning of the cell culture, without affecting cell activation, cytokine production, and glucose metabolism. In fact, CD69 expression and IL4 secretion by CD4+ T lymphocytes was higher in the presence of 5 mM than the untreated cells in both glucose conditions. Overall, metformin inhibited proliferation through mechanisms associated with cell cycle arrest, leading to an increase in the S/G2 phases at the expense of G1 in activated CD4+ T lymphocytes in normo- and hyperglycemic conditions. Despite the cell cycle arrest, activated CD4+ T lymphocytes remained metabolically, functionally, and phenotypically activated.

Bioactive extract of Morchella esculenta ameliorates cyclophosphamide-induced mitochondrial dysfunction and cardiotoxicity by modulating KEAP1/NRF2 and pro-inflammatory genes expression

Prevention of anticancer drugs-induced cardiotoxicity remains an imperative area of oncology research as it continues to be a major challenge in cancer chemotherapy. This study was undertaken to investigate the protective effect of methanol extract of Morchella esculenta (ME) against cyclophosphamide (CP)-induced cardiotoxicity. Myocardial damage was assessed by biochemical and histopathological methods. Proinflammatory cytokines gene expression was determined by RT-PCR analysis. To assess the mitochondrial dysfunction, TCA cycle and electron transport chain complexes enzymes activities were determined. Chemical finger print of ME was accomplished by HPTLC. CP (200 mg/kg) treated animals showed elevation in cardiac injury markers which was attenuated by ME (p < 0.05). CP-induced decline of antioxidant status and expression of nuclear factor erythroid 2-related factor 2 were restored by ME. CP-induced expression of NF-ĸB, IL1-β, IL-6, TNF-α, COX-2 and iNOS (p < 0.05) was attenuated by ME (500 mg/kg). Bioactive compounds namely, 5-eicosapentaenoicacid (C20H30O2), 8-hydroxyoctadecadienoic acid (C18H32O3), 4,4-dipo-zetacarotene (C30H44), CynarosideA (C21H32O10) present in the extract might be responsible for cardioprotection. The findings reveal the protective effect of ME against CP-induced cardiomyopathy.

Penggunaan Media Audio Visual untuk Meningkatkan Kemampuan Memahami Isi Teks Narasi pada Siswa Kelas IV SD

This research aims to improve the understanding of class IV students at SD Negeri 25 Palembang by utilizing audio-visual sources. The four steps of classroom action research (CAR) are planning, implementing, observing, and reflecting. This process is completed in two cycles. Two ways of collecting data are through observation and assessment of learning outcomes. Meanwhile, the data analysis procedure includes qualitative descriptive data, the research instrument uses observation sheets and multiple choice evaluation questions. Based on research findings, fourth grade students at SD Negeri 25 Palembang understand fairy tales more deeply than their friends. Observing instructor activities in cycle I produced findings that were in the good category at 80%, while cycle II obtained results that were in the very good category at 94%. In cycle II the results of monitoring student activities were 91% in the very good category, while in cycle I the results were 78% in the good category. After completing the first cycle of learning, there were 14 students who obtained a learning achievement of 45.16%, while 17 students obtained a learning achievement of 54.84%. The results of cycle II showed that student learning outcomes were appropriate, namely 29 students had completed their studies with a learning achievement score of 93.54%, and 2 students had not completed their studies with an exposure score of 6.46%. This shows that fourth grade students at SD Negeri 25 Palembang can understand narrative texts better if they use audio-based visual media.

Investigation of the Contribution of Five Broadcast Ionospheric Models (GPSK, NTCMG, NEQG, BDGIM, and BDSK) and IRTG to GNSS Positioning During Different Solar Activities in Solar Cycle 25

AbstractAdditional ionospheric information is essential for mitigating errors in single‐frequency (SF) Global Navigation Satellite Systems (GNSS) positioning. The increasing number of low‐cost dual‐frequency (DF) receiver users faces limitations in tracking DF observables compared to traditional geodetic receivers. Consequently, ionospheric correction algorithms (ICAs) are also essential for low‐cost DF devices in hybrid‐frequency positioning. To evaluate the performance of commonly used ICAs during solar cycle 25, our study presents a global statistical investigation of the contribution of five broadcast ionospheric models (BIMs) and the International GNSS Service (IGS) combined real‐time global ionospheric maps (IRTG) to the positioning domain, covering both quiet and perturbed ionospheric conditions. The BIMs investigated include the GPS Klobuchar (GPSK), Galileo NequickG (NEQG), NTCM‐GlAzpar (NTCMG), BDS‐2 Klobuchar (BDSK), and BeiDou Global Ionospheric delay correction Model (BDGIM). Experimental results from standard point positioning indicate that IRTG demonstrates superior overall accuracy compared to all BIMs, with a mean 3D root mean squared (RMS) of 2.76 m during perturbed period. Specifically, GPSK, NTCMG, NEQG, BDGIM, and BDSK exhibit RMS values of 2.03, 1.67, 1.72, 1.62, and 2.36 m during quiet conditions, and 4.02, 3.17, 2.86, 3.14, and 4.44 m during perturbed conditions, respectively. Among the BIMs, NEQG demonstrates superior performance at middle and high latitudes but exhibits lower accuracy than NTCMG and BDGIM at low latitudes during daytime under quiet conditions. BDGIM performs slightly better than NTCMG at low latitudes but slightly worse at high latitudes. BDSK shows notable improvement for high‐ and mid‐latitude regions since 3 June 2020.

Can plants build their niche through modulation of soil microbial activities linked with nitrogen cycling? A test with Arabidopsis thaliana.

In natural systems, different plant species have been shown to modulate specific nitrogen (N) cycling processes so as to meet their N demand, thereby potentially influencing their own niche. This phenomenon might go beyond plant interactions with symbiotic microorganisms and affect the much less explored plant interactions with free-living microorganisms involved in soil N cycling, such as nitrifiers and denitrifiers. Here, we investigated variability in the modulation of soil nitrifying and denitrifying enzyme activities (NEA and DEA, respectively), and their ratio (NEA : DEA), across 193 Arabidopsis thaliana accessions. We studied the genetic and environmental determinants of such plant-soil interactions, and effects on plant biomass production in the next generation. We found that NEA, DEA, and NEA : DEA varied c. 30-, 15- and 60-fold, respectively, among A. thaliana genotypes and were related to genes linked with stress response, flowering, and nitrate nutrition, as well as to soil parameters at the geographic origin of the analysed genotypes. Moreover, plant-mediated N cycling activities correlated with the aboveground biomass of next-generation plants in home vs away nonautoclaved soil, suggesting a transgenerational impact of soil biotic conditioning on plant performance. Altogether, these findings suggest that nutrient-based plant niche construction may be much more widespread than previously thought.

Penerapan Model Discovery Learning Berbantuan Geogebra Untuk Meningkatkan Hasil Belajar Siswa Kelas XI MIA SMAN 1 Wulla Waijelu Kabupaten Sumba Timur Pada Materi Lingkaran

This research was motivated by the low learning outcomes of class XI MIA at SMAN 1 Wulla Waijelu, East Sumba Regency on circle material. The aim of this research is to describe the application of the geogebra-assisted discovery learning model to improve the learning outcomes of class XI MIA students at SMAN 1 Wulla Waijelu, East Sumba Regency on circle material. The research method used is Classroom Action Research (PTK), with qualitative and quantitative data types. This research was carried out in class XI MIA at SMAN 1 Wulla Waijelu, East Sumba Regency, totaling 22 students. Data collection techniques in this research were through observation, tests and questionnaires, with the instruments used namely teacher and student observation sheets, test questions and student response questionnaires. Implementation of this Classroom Action Research has 4 stages, namely 1) Planning; 2) Implementation of action (action); 3) Observation; 4) Reflection. The research results show that the percentage of completeness of students' classical learning outcomes at the end of cycle I reached 85.71%, which meets the success indicators of this research. The implementation of the teacher ability level score (TKG) in cycle I reached 93.96 and was in the very good category. In addition, the implementation score of student activities in cycle I reached 88.33 and was in the very good category.

Research on cycling power estimation and prototype of a GPS bike computer based on system-on-chip platform

A GPS (Global Positioning System) bike computer is a specialized electronic device that allows for recording the traveled trajectory and training parameters of cycling activities. Current GPS bike computer devices on the market often do not provide cycling power parameter to support the riders. This paper presents a method to efficiently estimate cycling power based on the ground speed and altitude variation of the bike. The suggested method can be applied in the design and implementation of bike computers on embedded systems. The paper also presents the design and implementation of a GPS bike computer prototype based on a System-on-Chip platform.

Pengaruh Penggunaan Media Film Terhadap Peningkatan Keterampilan Menulis Teks Tanggapan di SMP Negeri 4 Madiun

Through the research activities carried out, students are invited to change their views, so that writing responses becomes a fun learning activity. The aim of the research was to see the effect of using film media on improving response text writing skills. In this activity, the type of research is classroom action research (PTK), then the method used is qualitative and quantitative descriptive analysis with the target subject being class VII D students at SMP Negeri 4 Madiun. Based on data sources using primary data obtained from research subjects through initial stage collection techniques of tests, interviews and observations. Checking the validity of the data uses the results of students' grades by considering the increase in learning outcomes in each phase of the cycle starting from the pre-cycle, cycle I and cycle II stages. Analysis of research data carried out qualitative and quantitative analysis. The results of the research show that there is an influence of the use of film media on response text writing skills which has increased starting from the initial pre-cycle results with a percentage of 46.87% up to the first cycle stage showing quite good improvement with a completion percentage of 56.25% and cycle activities. II with a completion score percentage of 84.37% which shows an increase.

Efforts to Improve Students' Analytical Skills in Islamic Religious Education Learning by Using the Discovery Learning Model

The purpose of this study is to improve students' analytical skills in Islamic Religious Education subjects. This classroom action research was carried out with a time allocation of 3 teaching hours, 2 meetings and implemented in 2 cycles. If the first cycle has not shown the expected results, it will be continued in the next cycle (cycle II). iii Actions in cycle II are improvements and refinements of the actions carried out in cycle I. Therefore, the actions in cycle II were carried out by looking at the results of observations of teaching and learning activities and student learning outcomes in cycle I. The material taught in accordance with the Mapping of Competency Standards, Basic Competencies and Indicators in class XI is material about faith in the books of Allah. The learning outcomes obtained by students through written tests at the end of the lesson for cycle I were 10 students (50%) who had achieved learning completion and there were still 10 students (50%) who had not achieved learning completion with student absorption reaching 77.69%. In cycle II there was an increase to 20 people (100%) who achieved learning completion with student absorption reaching 83.9%. Observations on teaching and learning activities in cycle I 5 aspects (62.5%) obtained good criteria and 3 aspects (37.5%) obtained sufficient criteria. In the second cycle increased to 7 aspects (87.5%) obtained good criteria and only 1 aspect (12.5%) obtained sufficient criteria Based on the results of the research and discussion conducted, it is clear that through the Discovery Learning Learning Model and its use in Islamic Religious Education subjects for the material of faith in the books of Allah, students experienced an increase in learning outcomes. Likewise, in the implementation of learning there was an increase in Suggestions, the use of appropriate and interesting media, time allocation and student organization need to be considered in order to achieve efficiency and effectiveness of student learning outcomes.

Penerapan Model Pembelajaran Picture And Picture Untuk Meningkatkan Hasil Belajar Siswa Materi Bangun Datar Pelajaran Matematika Kelas I SD Alfityah Pekanbaru

The low learning outcomes of students in flat shapes material in grade 1 elementary school mathematics lessons is the main problem faced. Students often have difficulty understanding the basic concepts of flat shapes taught conventionally. The aim of the research is to improve student learning outcomes by using the Picture and Picture learning model for Flat Building Material in Mathematics Lessons. This research method includes Classroom Action Research (PTK) which was carried out in two cycles. Each cycle consists of four stages, namely design, implementation, observation and reflection. The research results obtained are (1) teacher activity in cycle I using the Picture and Picture learning model from 83.92% to 92.85% in the cycle II, (2) student activities in cycle I using the Picture and Picture model 75% to 91% in cycle II and (3) learning outcomes for Flat Figure material in Mathematics lessons in cycle I using the Picture and Picture model 60% to 90% in cycle II. This shows that the student learning outcomes for Mathematics Lesson Flat Figure Material using the Picture and Picture Learning model show very positive results.

Design, Fabrication, and Evaluation of 3D Biopotential Electrodes and Intelligent Garment System for Sports Monitoring.

This study presents the development and evaluation of an innovative intelligent garment system, incorporating 3D knitted silver biopotential electrodes, designed for long-term sports monitoring. By integrating advanced textile engineering with wearable monitoring technologies, we introduce a novel approach to real-time physiological signal acquisition, focusing on enhancing athletic performance analysis and fatigue detection. Utilizing low-resistance silver fibers, our electrodes demonstrate significantly reduced skin-to-electrode impedance, facilitating improved signal quality and reliability, especially during physical activities. The garment system, embedded with these electrodes, offers a non-invasive, comfortable solution for continuous ECG and EMG monitoring, addressing the limitations of traditional Ag/AgCl electrodes, such as skin irritation and signal degradation over time. Through various experimentation, including impedance measurements and biosignal acquisition during cycling activities, we validate the system's effectiveness in capturing high-quality physiological data. Our findings illustrate the electrodes' superior performance in both dry and wet conditions. This study not only advances the field of intelligent garments and biopotential monitoring, but also provides valuable insights for the application of intelligent sports wearables in the future.

Sezonowa i przestrzenna zmienność jakości wody w systemie jezior Lumina-Rosu w delcie Dunaju w Rumunii

The main aim of the present scientific paper is to assess water quality of the surface water of various lakes located in the Lumina-Rosu interdistributary depression, Danube Delta, Romania. As specific objectives, the paper considered to spot the main potential sources of contamination and their environmental impacts on aquatic ecosystems. Equally, the purpose of the article is to emphasize the importance of monitoring the water quality of the Danube Delta, for preserving these unique natural water resources and their ecosystem services (fresh water, biodiversity, flood control, recreation, nutrient cycling, fishing and other traditional activities, ecotourism). Surface water samples collected from several control sections situated on the main tributaries and canals, as well as from lakes were investigated physically (To - C, EC - μS/cm, TDS - mg/L, turbidity - NTU units, TSS - mg/L) and chemically (pH - units, DO - mg/L, N-NO2- - mg/L, N-NO3- - mg/L, P-PO43-- mg/L, Chla - mg/L, SiO2 - mg/L, TOC - mg/L, SO42- - mg/L, S2- - mg/L, H2S - mg/L and synthetic detergents - mg/L). Generally, the hydro-physical-chemical characteristics and water quality assessment of the surface waters of the lakes manifest the combined effect of both processes occurred in the catchment (weathering, sediment supply and transport), as well as the in situ lake processes (photosynthesis, sediment mixing, biogeochemical cycling, evaporation, eutrophication, productivity changes). Overall, the physical and chemical characteristics of the sampling sites investigated at high waters of the Danube are quite similar to those measured at low waters. The differences that mainly occurred within the lakes are more related to the limnological variables and the local environmental conditions. Anyway, a significant seasonal variation was noticed in the lakes, during the dry period, when different physical and chemical characteristics appeared to be influenced by high air temperature, lack of precipitation, low water level regime, low dissolved oxygen level regime, all related to climate change effects etc. Moreover, the anthropogenic factor that left its mark on some physical-chemical characteristics of water should not be omitted either. However, the results obtained within this study did not show such alarming values as might have dangerous effects on the investigated aquatic environments. The water quality information within this case study may be used for improving the understanding of the water quality issues and to better coordinate and plan for future monitoring activities in and around the Danube Delta environment. The results will contribute to updating the existing database with relevant information for a sustainable future of the Danube Delta and in similar areas that are subjected to such environmental challenges.

Drought stress impacts soil microbial nutrient limitation more strongly than O3 pollution

Summer drought conditions generally coincide with exposure to high ground-level concentrations of ozone (O3). These two stressors compromise the availability of water, energy, and nutrients to vegetation and microbial communities present within the soil. However, relatively little is known regarding the responses of rhizosphere and non-rhizosphere soil microbial nutrient acquisition to conditions of drought and O3 exposure. Here, we used ecoenzymatic stoichiometry modeling and vector analyses to decipher the resource constraints on rhizosphere and non-rhizosphere soil microbial metabolic limitation within the soil of hybrid poplars exposed to two watering regimens (well-watered or reduced water of 40 %) and two chronic O3 treatments (charcoal-filtered air or ambient air +40 ppb of O3). Results show that, simulated drought stress resulted in stronger effects on the structure of soil microbial communities and associated enzymatic activity relative to exposure to elevated O3 levels. Exposure to these two stressors induced a microbial phosphorus (P) limitation response, with these limitation effects being more pronounced in the rhizosphere soil relative to non-rhizosphere soil. Structural equation modeling revealed that drought-associated declines in soil water availability and pH values were the primary factors influencing this microbial P limitation. Reduced soil water levels resulted in the exacerbation of microbial P limitation as a consequence of the inhibition of P mineralization and availability of C and N, whereas declining soil pH values had the opposite effect, alleviating microbial P limitations by reducing soil alkalinity and thereby aiding in the dissolution of the insoluble P present in alkaline soil. These results emphasize the complex responses of rhizosphere and non-rhizosphere soil microbial metabolic activity to elevated O3 levels and drought stress, providing invaluable insight into the importance of elemental stoichiometry-driven microbial metabolic variability of nutrient cycling activity at the root-soil interface in O3-polluted and drought-exposed ecosystems.