Chemical Characteristics Research Articles

Enhancing detection of thermal runaway gases: Exploiting doping and vacancy effects in GeS quantum dots

This study investigates chemical modifications on Germanium Sulfide (GeS) quantum dots (QDs) for selective detection of thermal runaway gases (TRGs). We examine how doping with oxygen, phosphorus, silicon, and introducing sulfur vacancies at edge and surface regions affect the structural, electronic, and optical properties of GeS-QDs and their derivatives. Our findings reveal significant changes in bond parameters, formation energy, electronic band gap, and light absorption behavior. Oxygen doping enhances stability, while other dopants and sulfur vacancies increase reactivity towards TRGs (H2, CO, CH4, C2H4). All materials show favorable adsorption for these gases, with C2H4 displaying the strongest binding affinity. Adsorption minimally affects core electronic structure (HOMO) but shifts surface electronic states (LUMO). Sulfur vacancies reduce the energy gap, enhancing conductivity and facilitating TRGs detection. These results suggest that GeS-QDs can be effectively tuned for selective TRG detection by manipulating their chemical composition and surface characteristics.

Modulation of fecal microbiota and reductions in fecal antibiotic resistance genes (ARGs) driven by Weissella-fermented feed in growing pigs

Probiotics-induced feed fermentation can improve the composition of microbiota, leading to benefits in pig production. However, the influence of probiotics-driven feed fermentation on pollution reduction is limited. This study aimed to analyze the impact of Weissella-based feed fermentation on the chemical characteristics, changes in microbial abundance, and antibiotic resistance genes (ARGs). Moreover, the possible mechanism and the association among them was also analyzed. First, pigs reared on fermented feed exhibited improved growth performance. The fermentation group showed a significant reduction in emissions of total phosphorus (TP), total carbon (TC), organic matter (OM), copper (Cu), and zinc (Zn) levels in feces compared to the control group. The fermentation group also showed a significant decrease in the ARGs, especially for the tetX, tetW, tetQ, tetL, tetO, tet32, tet44, ermG, ermF, CfxA2, CfxA3, aph3-III, aadA, and ant9-I, compared to the control group. The primary functional microbiota, characterized by increased levels of Bifidobacterium, Megasphaera, and Mitsuokella, and decreased levels of Methanosphaera, and Ruminiclostridium, displayed both negative and positive correlations with ARGs, TC, TP, OM, Cu, and Zn. Furthermore, a significant association was observed between the alterations in microbiota and ARGs and the lactic acid concentration in the fermented feed. The molecular docking results showed a good fit between lactate dehydrogenase and three antibiotics, particularly tetracycline. In conclusion, these results offer novel targets and strategies to address environmental pollutants associated with pig farming.

Chemical Characterization and Temporal Variability of Pasta Condiment By-Products for Sustainable Waste Management.

Sustainable waste management is an extremely important issue due to its environmental, economic, and social impacts. Knowledge of the chemical composition of the waste produced is a starting point for its valorization. This research focuses, for the first time, on the by-products of pasta condiment production, starting with their characterization. In particular, the presence of potential bioactive compounds and their variability over time have been studied. The latter aspect is crucial for the subsequent valorization of these by-products. In addition to acidity and total phenolic content, an untargeted strategy was adopted, using spectroscopic and chromatographic techniques coupled with chemometrics, to study waste samples coming from four single condiment production lines, i.e., Genoese pesto, tomato, ricotta, and ragù sauces. The presence of lycopene, polyphenols, and several valuable volatile compounds was highlighted. Their presence and relative amounts vary mainly according to the presence of tomatoes in the sauce. The results obtained at different storage times (after 0, 7, 10, and 15 days) showed that the samples studied, despite having similar chemical characteristics, underwent changes after one week of storage and then presented a relatively stable chemical profile. A general decrease is observed after 7 days for almost all the chemical variables monitored, so careful planning within the first days is required to obtain a high recovery.

Reformulation of gambang bread with additional pectin and coconut dregs powder as wheat flour and breadcrumb substitute

Gambang bread is a traditional no-yeast Indonesian bread characterized by its palm sugarlike brown colour, dense texture, and spice taste. Coconut dregs are high in dietary fiber but easy to spoil, so blanching is an effective way to prolong the coconut dregs' shelf life. This study investigated the effects of the blanching method and time on yield, water content, fat content, and dietary fiber content of coconut dregs powder. Moreover, the effects of coconut dregs powder substitution ratio and pectin concentration on the microstructure and physical characteristics of the bread (expansion volume and hardness) were studied. Hot water blanching produced coconut dregs powder with lower yield and fat content, as well as higher moisture and dietary fiber content than steam-blanched coconut dregs powder. Blanching time only affected dietary fiber content. 10 mins of blanching produced coconut dregs powder with higher dietary fiber content than 5 mins of blanching. Hot water blanching treatment for 10 mins was chosen as the best treatment. This treatment produced 43.12±0.64% coconut dregs powder. Moreover, the chemical characteristics of chosen coconut dregs powder were 5.40±0.01% water, 34.10±1.56% fat, 3.73±0.1% protein, 0.45±0.02% ash, 55.53±1.28% carbohydrate, and 73.90±0.02% dietary fiber. Higher substitution of coconut dregs powder increased hardness and decreased the expansion volume of gambang bread. Meanwhile, adding pectin significantly reduced the hardness of gambang bread. The best gambang bread was obtained from 10% substitution coconut dregs powder and 0.5% additional pectin. Bread microstructure showed that substituting coconut dregs disrupted the continuity gluten matrix more than control bread.

Highly efficient adsorption of eosin yellow dye from aqueous solutions using polymer-based nanocomposite developed from cross-linked chitosan-citrate and Co2O3 nanoparticles

The utilization of polymer-based nanocomposites offers a particularly interesting method for removing organic dyes from waterways. This study aimed to efficient removal of eosin yellow (EOY) dye from aqueous solutions using polymer-based nanocomposite (hereinafter, CHA-CIT/Co2O3 NPs) prepared from crosslinked chitosan-citrate (CHA-CIT) and Co2O3 nanoparticles (Co2O3 NPs). The CHA-CIT/Co2O3 NPs adsorbent was investigated by several approaches like XRD, BET analysis, FTIR spectroscopy, FESEM-EDX, and pHpzc analysis, to get a thorough understanding of its structural and chemical characteristics. Box-Behnken design (BBD) was adopted to systematically optimize crucial adsorption parameters, including CHA-CIT/Co2O3 NPs dose (0.01–0.07 g), starting solution pH (4–10), and contact duration (10–40 min). The CHA-CIT/Co2O3 NPs nanocomposite's BET surface area was found to be 19.85 m2/g. The mean pore diameter was determined to be 4.3 nm, and the total pore volume was measured to be 0.0213 cm3/g. The average crystallite size of 23.22 nm is indicative of the CHA-CIT/Co2O3 NPs nanocomposite's mainly polycrystalline characteristics. The kinetic investigations showed an agreement with the pseudo-first-order model, while the equilibrium results agreed well with the Freundlich isotherm model, suggesting the presence of multilayer adsorption behavior. The adsorption capacity of CHA-CIT/Co2O3 NPs for EOY was found to be 650.03 mg/g at a temperature of 25 °C, highlighting its exceptional adsorption ability. The work introduces a novel and efficient chitosan nanocomposite as a potential adsorbent for the high-performance removal of organic dyes from water-based solutions.

Assessment of soil chemical characteristics in the context of Bangladesh: A comprehensive review

This study presents a thorough examination of the chemical properties inherent to soil, with a focus on the unique context of Bangladesh. Soil functions are intricately linked to its chemical composition, which plays a vital role in determining agricultural productivity and ecological vitality. The soil within Bangladesh's geographical boundaries is characterized by its richness and fertility, contributing significantly to its agricultural output and overall ecosystem health. By delving into the chemical properties of Bangladeshi soil, this review aims to enhance our understanding of this dynamic ecosystem. Insights gained from this exploration can shed light on factors influencing soil fertility, nutrient availability, and overall ecosystem health, thereby informing strategies for sustainable land management and agricultural practices in Bangladesh and beyond.

Electronic structure, phonons, and optical properties of nitrogen-enriched 5-aminotetrazolium nitrate (5-ATN)

Tetrazoles, with their unique properties, are prominent candidates for advanced energetic materials in materials science. Understanding their physical and chemical characteristics is crucial for enhancing performance and innovating new tetrazole-based compounds. In this study, we utilize first-principles calculations to investigate the properties of nitrogen-enriched 5-Aminotetrazolium Nitrate (5-ATN), aiming to advance its application as an energetic material. Our extensive analysis includes the structural, mechanical, vibrational, optical, and electronic properties of 5-ATN. Theoretical results, especially with van der Waals (vdW) corrections, align well with experimental data. Elastic constants confirm mechanical stability and reveal differential shock sensitivities, particularly along the b-axis. Infrared spectral analysis identifies unique fingerprint peaks, crucial for detection. The electronic structure, determined using the Tran-Blaha modified Becke-Johnson (TB-mBJ) potential, yields an energy band gap of approximately 4.5 eV, overcoming the underestimation issues of traditional LDA and GGA methods. Optical constant variations indicate anisotropy and suggest potential photodecomposition in the ultraviolet (UV) spectrum. This investigation provides critical insights to guide the design and optimization of tetrazole-based energetic materials, enhancing their efficiency, stability, and performance in high-energy applications.

Unlocking higher yields in Urochloa brizantha: the role of basalt powder in enhancing soil nutrient availability

This study investigates the effect of basalt powder on soil fertility through changes in its chemical characteristics and the response of Urochloa brizantha to different application doses. The experiment was conducted in a greenhouse using two distinct soil types: Oxisol (OX) and Typic Quartzipsamment (TQ). Basalt powder dosages were determined based on the calcium levels required to adjust calcium contents in each soil (Ca2+) to recommended levels for the U. brizantha,ranging from 0 to 4 times the recommended amount. After 170 days of incubation, soil samples were collected for analysis to evaluate soil attributes. U. brizantha was then planted to assess the efficiency of basalt powder, which was harvested at 40 days after sowing (first cut) and 70 days after sowing (second cut). The accumulation of nutrients and shoot dry mass (SDM) production were subsequently measured. The findings revealed that applying the highest dose of basalt powder (96 Mg ha−1) substantially elevated pH, and increased concentrations of phosphorus (P), potassium (K+), calcium (Ca2+), magnesium (Mg2+), copper (Cu), boron (B), and silicon (Si) in Oxisol (OX), while decreasing aluminum (Al3+) contents in the same soil. Furthermore, an average increase in the SDM of both U. brizantha harvests was observed, with a 6% increase in TQ and a 27% increase in OX. Additionally, an increase in the accumulation of P, K, Ca, Mg, and sulphur (S) in the shoot dry mass of the plants was observed with the basalt powder doses. These findings suggest that basalt powder has the potential to be an environmentally friendly alternative for soil fertilization, with positive impacts on soil chemical attributes and plant growth and nutrition.

Bioflavonoid Daidzein: Therapeutic Insights, Formulation Advances, and Future Directions.

Bioflavonoids, are a diverse group of phytonutrients that are widely distributed in fruits, vegetables, grains, teas, and certain medicinal herbs. They are characterized by their antioxidant properties and play essential roles in plant biology, such as providing color to fruits and flowers, protecting plants from environmental stresses. Daidzein, a bioflavonoid classified under natural products, is sourced from plants like soybeans and legumes. It exists in forms such as glycosides and aglycones, with equol and trihydroxy isoflavone being key metabolites formed by gut bacteria. Known for its wide-ranging therapeutic potential, daidzein has shown effects on cardiovascular health, cancer, diabetes, skin conditions, osteoporosis, and neurodegenerative disorders. Its mechanisms include interaction with estrogen receptors, antioxidative and anti-inflammatory properties, and modulation of apoptosis and cell cycles. Recent advances in formulation technologies aimed at enhancing daidzein's bioavailability and efficacy are critically evaluated, including nanoparticle-based delivery systems and encapsulation strategies. Researchers have developed advanced formulations like nanoparticles and liposomes to enhance daidzein's solubility, stability, bioavailability, and targeted delivery. Considered a promising nutraceutical, daidzein warrants further exploration into its molecular actions and safety profile to fully realize its clinical potential. This review offers a succinct overview encompassing therapeutic benefits, chemical characteristics, historical uses, toxicology insights, recent advancements in delivery systems, and future directions for daidzein research.

Sensory and organoleptic assessment from the byproducts of mamoncillo or quenepa Melicoccus bijugatus Jacq: Alternative food processing and morpho-physiological characterization of the fruit

This research aims to analyze the morpho-physiological characteristics of ripe fruit and assess the feasibility and acceptability of agro-industrial byproducts derived from mamoncillo or quenepa (Melicoccus bijugatus Jacq) fruit. In addition to this, it was considered to be the optimal harvest point, which begins at 69% of the Maturity Index. In addition, evaluations of the chemical and morphological characteristics were carried out. To gather analytical scales and calibrator data, the two ripeness phases were analyzed and compared, using the maturity index to establish the optimal harvest point. Ripe fruits have increased shell, juice, pulp, seed, length, width, and thickness than unripe fruits, with 69% maturity being best. Further, it is possible to use the pulp of Melicoccus bijugatus to make syrup, jam, or jelly among other things. For this reason, the hedonic test was conducted with panelists who had not received any prior training in order to ascertain the level of acceptance of these innovative products. The analyses showed that the highest rank given through the panelists by the hedonic test and ranks of taste was "P-2 Pattern-2" with an X = 55.5 (Rank) which is a substitute pattern "Lychee in syrup", the second-highest was X = 52 which is "T-1 Treatment i.e. Melicoccus bijugatus Jelly"' followed by "T-2 Treatment i.e. M. bijugatus in syrup" with X = 51 Rank. According to the findings of the statistical analysis, the various agro-industrial byproducts derived from Melicoccus bijugatus were positively received.

Predicting the properties of bitumen using machine learning models trained with force field atom types and molecular dynamics simulations

This study enhances the molecular analysis of bitumen by transitioning from traditional chemical descriptors, such as SARA (Saturates, Aromatics, Resins, and Asphaltenes) fractions and elemental compositions, to specific force field atom types in Molecular Dynamics (MD) models. This shift improves the precision in predicting material properties critical for bituminous material characterization. Machine Learning Models (MLMs) were developed to use these atom types as input features, inherently reflecting fundamental chemical characteristics. Trained on data from over 1,770 LAMMPS simulations of diverse bitumen types and conditions, these MLMs enable the prediction of properties like density, heat capacity, solubility parameters, and thermal expansion coefficients without the need for additional MD simulations. The models utilize 30 chemical descriptors corresponding to specific atom types in the PCFF force field, which collectively account for over 95% of the influence on these properties. By accurately predicting fundamental, thermodynamic, and kinetic properties, the use of MLMs and force field atom types allows researchers to efficiently tweak the chemical nature of organic molecules and mixtures to achieve desired properties. With near-instantaneous prediction times, these MLMs offer valuable insights for advancing bitumen research in the construction and petroleum industries, reducing the need for more intensive simulation techniques.

Exploring Biosurfactants as Antimicrobial Approaches.

Antibacterial resistance is one of the most important global threats to human health. Several studies have been performed to overcome this problem and infection-preventive approaches appear as promising solutions. Novel antimicrobial preventive molecules are needed and microbial biosurfactants have been explored in that scope. Considering their structure, these biomolecules can be divided into different classes, glycolipids and lipopeptides being the most studied. Besides their antimicrobial activity, biosurfactants have the advantage of being biocompatible, biodegradable, and non-toxic, which favor their application in several areas, including the health sector. Often, the most difficult infections to fight are associated with biofilm formation, particularly in medical devices. Strategies to overcome micro-organism attachment are thus emergent, and it is possible to take advantage of the antimicrobial/antibiofilm properties of biosurfactants to produce surfaces that are more resistant to the deposition/attachment of bacteria. Approaches such as the covalent bond of biosurfactants to the medical device surface leading to repulsive physical-chemical interactions or contact killing can be selected. Simpler strategies such as the absorption of biosurfactants on surfaces are also possible, eliminating micro-organisms in the vicinity. This review will focus on the physical and chemical characteristics of biosurfactants, their antimicrobial activity, antimicrobial/antibiofilm approaches, and finally on their structure-activity relationship.

Biological activity and chemical characteristics studies of new oligomannose produced by Erwinia gerundensis

Natural polymers have attracted considerable attention in recent decades among scientists due to their potential therapeutic uses, particularly as antimicrobial and antitumor agents. In this research, novel EPSs were extracted from garlic rhizosphere bacteria. The antibacterial and antitumor activities of the polymer were evaluated through biological assays. The antibacterial activity was tested against gram-positive microorganisms (such as Listeria monocytogenes, Bacillus cereus, and Staphylococcus aureus) and gram-negative organisms (such as Shigella sonnei and Escherichia coli). The most significant inhibition zone was observed with Listeria monocytogenes and S. typhi, measuring 35 mm, while the most miniature antibacterial effect was seen with Staphylococcus aureus at 23.67 mm.Furthermore, the inhibitory effect of the crude polymer was assessed using a broth medium with two strains of E. coli and Bacillus cereus. Electron microscope images displayed varying degrees of damage to bacterial cells in the treated broth. The antitumor activity was determined using the MTT test on colon carcinoma cells (HCT-116), hepatocellular carcinoma cells (HepG-2), and CaCO2 (intestinal carcinoma cells), with IC50 values of 188.86±6.17 µg/mL, 221.66±8.02 µg/mL, and 203.65±7.43 µg/mL, respectively, after 48 h. The bacteria responsible for polymer production were isolated from garlic plant rhizospheres and identified as Erwinia gerundensis CCASU-2024–69 through 16S rRNA sequencing. FTIR and NMR techniques determined the crude EPS's main components and functional groups, including carbonyl, carboxylic, methylene, and silanol. GC–MS analysis revealed 34 bioactive compounds, while HPLC analysis indicated that the EPS was a hetero-monosaccharide consisting of d-xylose, d-glucose, l-arabinose, ribose, and d-mannose. This research study represents the initial exploration into the exopolysaccharide derived from Erwinia gerundensis. To assess the interaction between the exopolysaccharide and the active sites of Bacillus cereus and E. coli, molecular docking experiments were conducted using five monosaccharides: d-xylose, d-glucose, l-arabinose, ribose, and d-mannose. The data obtained from the molecular docking analysis strongly correlates with the findings from biological studies.Furthermore, these highly active compounds exhibit a favorable proposed ADMET profile. This particular exopolysaccharide shows potential as a natural antibiotic and holds promise in treating gastrointestinal cancer. A comprehensive assessment of laboratory animals is essential before its potential use as a prebiotic in nutrition.

Chemical, elemental, morphological and toxicological characteristics of traditional Indian Siddha formulation: Kasthuri Karuppu

AbstractThe chemical, elemental, morphological and toxicological characteristics of organometallic formulation (Kasthuri Karuppu) were assessed using UV-spectrophotometer, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, ICP-OES, Energy dispersive X-ray, XRD and Zeta potential. The physical properties such as size (10–80 nm), surface area (3.1 m2/g), surface charge (-36mV), and bandgap energy (3.6 eV) were correlated with reactivity. Based on the elemental distribution of Hg, As and S, the proportion favours HgS that is less toxic and reactive. There were no toxic effects of the tested formulation at concentration 60 µg/mL against normal and cancer cells (observed during 24 h). However, the increase in time duration (72 h) had lethal effects in both the cells. The developmental toxicity of the organometallic formulation was assessed in Zebrafish embryos. The safe dosage was found to be 100 µg/mL. The toxicity of the formulation in vitro and in vivo is based on the exposure time and dosage.

Prediction of strength activity index using chemical and physical properties of pozzolans

Reductions in cement use have essential benefits in reducing the embodied energy in concrete and CO2 emissions. Hence, effective assessment of potential pozzolanic materials is highly desirable to facilitate usage as sustainable supplementary cementitious materials (SCMs). However, assessment of pozzolanic reactivity using conventional experimental tests is typically time-consuming and expensive. Pozzolanic reactivity is mainly related to the chemical and physical characteristics of various pozzolans, such as amorphous silica and alumina contents and specific surface area. This study develops and presents an equation that can predict the strength activity index (SAI) as an indirect method for the assessment of potential pozzolans and their strength outcome using their chemical and physical properties. The development of a prediction equation not only saves time and resources but also helps with designing optimized and improved pozzolanic SCMs. The strength activity index (SAI) of seven different materials with varying pozzolanic properties was measured at an age of 90 days. The powdered test materials included pottery cull, brick powder, lightweight aggregate fines, glass powder, silica fume, dolostone, and Class C fly ash. In the second stage, correlation analyses were performed to find parameters (based on chemical and physical properties) that were highly correlated with SAI. An equation was then developed as a function of the chemical and physical properties of raw pozzolanic materials using an optimization tool. Consequently, an equation predicting SAI was derived which had a high degree of correlation (R = 0.972) with measured SAI.

Process and mechanism of termite impact on soil and plant.

Termites, as a kind of nesting social insects, are often confused as worldwide "pests" because some of their groups have great destructive effects. The vast majority of termites can regulate ecosystem functions and ser-vices by participating in biogeochemical cycles, known as "ecosystem engineers". We reviewed studies on the effects of termites on the physical, chemical and biological characteristics of mound soil ecosystems and the composition and diversity of plant communities. Termites could form unique soil "biogenic aggregates" and "resource heterogeneity patches", which affect microbial community structure, extracellular enzyme activity, physicochemical property and greenhouse gas emission, thereby affecting plant growth, community composition and structure, and vegetation productivity. However, this effect significantly differed among termite groups and functional groups, and was dependent on regional soil environment and microclimate conditions. Meanwhile, termite-mound could effectively improve ecosystem adaptation or resistance to environmental stress through the above process. Future research should focus on the following directions: 1) studying the trophic cascading effect of termite-centered soil multilevel biological network and the potential effect on biogeochemical cycle from microscale (aggregate level) to macroscale (landscape level); 2) exploring the potential of termite mound soil as a fertility amendment in tropical regions, and mining beneficial microbial functional genes to develop related products for termite control.

QUALITY AND SAFETY PARAMETERS BEFORE AND AFTER PASTEURIZATION OF APPLE JUICE

The research was carried out in September (2023) on the premises of the “Kosovo Agricultural Institute” in the city of Peja. The purpose of this research was to show the influence of pasteurization on the physical, chemical, and organoleptic characteristics of apple juice. During the study, several analyses of the physical, chemical, and sensory parameters of apple juice were carried out. The parameters that have been realized include: °Brix value, Total acidity, Vitamin C, pH and SO2, sensory parameters: aroma, color, taste, and clarity-turbidity. The purpose of this research is the importance of knowing the influence of some parameters on apple juice before and after pasteurization. Pasteurization of apple juice is of great importance due to various factors related to food safety, storage, and consumer health. In the analysis of sensory parameters, the juice before pasteurization had a milder and lighter aroma, had a lighter yellow color, tasted less sweet, less fresh, and had low acidity. Clarity was present but contained some turbidity. In the analysis of sensory parameters, the evaluation of physicochemical parameters and sensory parameters should contribute to valuable knowledge on the physicochemical transformations caused by pasteurization in apple juice. Understanding these changes is very important for maintaining product quality and ensuring customer satisfaction. The study provides a basis for optimizing pasteurization processes to minimize unwanted changes in juice characteristics.

An Innovative Water Splitting Process for a Sustainable In Situ Hydrogen Generation–Reduction of Nitrobenzenes Catalyzed by a New Bimetallic Nanocatalyst

ABSTRACTIn this research, bimetallic CdNi nanoparticles encapsulated in a magnetic spent coffee ground (Fe3O4@COFF/CdNi) was synthesized as a new nanocatalyst. The structural and chemical characteristics of Fe3O4@COFF/CdNi were comprehensively investigated using various techniques, including FT‐IR, XRD, XPS, TEM, VSM, EDS, TGA, BET, and ICP. Through XRD, XPS analysis, TEM images, and EDS mapping, the presence of CdNi nanoalloys was conclusively established. Fe3O4@COFF/CdNi exhibited remarkable catalytic activity for the hydrogen generation from water using iso‐propanol as a clean sacrificial agent. The high catalytic performance of Fe3O4@COFF/CdNi was attributed to the synergistic cooperative effect of Cd and Ni within CdNi nanoalloys. Interestingly, this process was performed for the in situ generated hydrogen from water to reduce a range of nitrobenzenes simultaneously into the corresponding anilines in high yields (93%–98%). The magnetic and hydrophilic characteristics of Fe3O4@COFF/CdNi facilitated its reusability over five runs. Using water as the most abundant hydrogen source, for the first time for in situ hydrogen generation–reduction of nitrobenzenes without demanding on external light sources or power supplies can be mentioned as a significant milestone of this field of study.

Evaluation of the Performance of Fiber-Reinforced Mortars Based on Dredged Sludge

River-carried solids, especially during floods, lead to dam sedimentation. Dredging extends dam life, but excess unusable sediment storage threatens the environment. The aim of this work is to investigate the influence of the recovery of calcined mud from Chorfa dam on the physico-mechanical and chemical characteristics of mortars fiber bundles. The sludge is used as a partial substitute for cement by volume at rates of 10%, 15%, 20% and 25%. All test specimens had water / binder (W/B) ratio and steel fibers ratio. Testing programme included measuring the fluidity, ultrasonic pulse velocity test, dynamic modulus of elasticity, flexural and compressive strengths. Compared to the control mortar, the fluidity represented by the diameter of M0, M15 and M25 mixtures decreased by approximately 11%, 14% and 22%, respectively. The compressive strength of M15 increased by 17.4% at 28 days, compared with the control specimen. At 7 days, the ultrasonic speed of the M25 mixture decreases by 1.7% compared to that of M15. The dynamic modulus of elasticity of M20 and M25 increases by 13% and 12% as the age ranges from 2 to 28 days. At 28 days, the flexural strength of the M20 blends increased by approximately 64%.

Local factors drive leaf breakdown in tropical streams

Plants of riparian forests provide abundant dead leaves for freshwater stream ecosystems which support detritus-based food webs. The increased replacement from natural riparian forests to Eucalyptus plantations, an exotic species distributed throughout the neotropic landscapes, alters leaf breakdown as a key ecosystem process. We evaluate the breakdown of native and exotic leaf species with distinct physical and chemical characteristics (traits) in two different tropical reference condition streams located in Cerrado and Atlantic Forest biomes. We tested the hypothesis that regardless of the leaves’ origin (native or non-native species), leaf litter with higher nutrients and less recalcitrant compounds has higher decay rates. Eucalyptus camaldulensis leaf breakdown was faster than the native species Miconia chartacea in both streams. Leaf breakdown was driven by local characteristics (context dependent) and the macrodecomposer community, with more intensity to the litter's intrinsic physical and chemical quality. The higher leaf breakdown of E. camaldulensis was evidenced in the Atlantic Forest stream, that with the most increased water flow, further accelerating the leaf breakdown. Our findings indicate that due to the innate physical and chemical characteristics of E. camaldulensis, its decomposition occurs at a faster rate compared to native tropical species, as evidenced by the stream flows.