The effect of alumina, carbon-coated alumina (CCA), and two commercial activated carbons (ACs) supports on trimetallic KCoMoS2 catalysts for ethanol conversion was studied. Supports and catalysts were characterized using high-resolution transmission electron (HRTEM) microscopy, UV spectral analysis of pyridine adsorption, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and N2 physisorption to study their structural properties and morphology. The reactions were carried out under hydrogen and helium reaction atmospheres in a fixed-bed reactor. Catalysts supported on various ACs were found to be more active than those supported on γ-Al2O3 and CCA. The turnover frequency (TOF) in all the studied reactions increased both with an increase in the average length (L¯) and with a decrease in dispersion (D). Product yields were higher under a helium atmosphere compared to a hydrogen atmosphere. Conversion of ethanol is supposed to occur on MoS2-based catalysts with account for the nature of the support and effects of the reaction atmosphere. The influence of catalyst acidity on product distribution and conversion was investigated; acidity was found to have no direct effect on total conversion, yet it influenced product yields.
Engineered nanostructures are materials with promising properties, enabled by precise design and fabrication, as well as size-dependent effects. Biomedical applications of nanomaterials in disease-specific prevention, diagnosis, treatment, and recovery monitoring require precise, specific, and sophisticated approaches to yield effective and long-lasting favorable outcomes for patients. In this regard, carbon nanofibers (CNFs) have been indentified due to their interesting properties, such as good mechanical strength, high electrical conductivity, and desirable morphological features. Broadly speaking, CNFs can be categorized as vapor-grown carbon nanofibers (VGCNFs) and carbonized CNFs (e.g., electrospun CNFs), which have distinct microstructure, morphologies, and physicochemical properties. In addition to their physicochemical properties, VGCNFs and electrospun CNFs have distinct performances in biomedicine and have their own pros and cons. Indeed, several review papers in the literature have summarized and discussed the different types of CNFs and their performances in the industrial, energy, and composites areas. Crucially however, there is room for a comprehensive review paper dealing with CNFs from a biomedical point of view. The present work therefore, explored various types of CNFs, their fabrication and surface modification methods, and their applications in the different branches of biomedical engineering.
Intensive clear-cutting of natural forests and conversion to monoculture plantations are ongoing worldwide, leading to the degradation of soil quality and microbial functions. Here, we compared soil quality index (SQI) and fungal communities in a natural forest (Forest) and four 5-year-old monoculture plantations, including Camellia oleifera (Oil), Amygdalus persica (Peach), Myrica rubra (Berry) and Cunninghamia lanceolate (Fir) in a subtropical region of China. After conversion, soil pH in the plantations rose up to 0.31, but organic carbon and total nitrogen contents, sucrase, acid protease, glutaminase, acid and alkaline phosphatase activities decreased by 83%, 59%, 40%, 64%, 66%, 94% and 59%, respectively. Correspondingly, the SQI dropped by 65%. High-throughput sequencing of the ITS1 region demonstrated an increase in α-diversity and a striking difference in β-diversity of fungi following conversion. Changes in the dominant fungal taxa following forest conversion to plantations were interpreted by r- and K-selection of life strategies. Conversion increased the fungal groups with r-strategies, such as Ascomycota and Zygomycota, but decreased the fungal groups with K-strategies, such as Basidiomycota. Genera affiliated to those phyla including Pseudophialophora, Rhytisma increased, but Russula decreased. Redundancy analysis and structural equation modeling indicated that the diversity and composition of fungal communities changed with soil degradation, which was mainly driven by increased pH and total phosphorus content, but decreased C/N ratio and C and N related enzymes activities. Overall, the conversion of forest to monoculture plantations decreased soil quality and the abundance of K-strategists, retarded the decomposition of persistent organic matter, but boosted the prevalence of r-strategists in a more diverse fungal community.
Under a precise nonlinearity-diffusivity assumption we establish the decay of entropy solutions of a degenerate nonlinear parabolic equation with initial data being a sum of periodic function and a function vanishing at infinity in the appropriate sense.
Biochar plays an important role in soil carbon (C) sequestration, while the effectiveness of sequestration is mostly determined by microbial preferences to utilize the different biochar components (i.e. labile substances or fused aromatic backbone). Thus, it is important to investigate the responses of the bacterial community and specific taxa, and associated C metabolic functions to biochar labile C (i.e. easily mineralizable C) or aromatic backbone (i.e. persistent C). Here, we separated the biochar components into labile C and aromatic backbone, and used the 16S sequencing in conjunction with the addition of an internal standard to quantify the absolute copy number of various bacterial taxa. The aromatic backbone decreased microbial metabolic quotient by 47 %, incorporating more C into biomass and contributing to C sequestration rather than releasing it into the atmosphere, while the labile C caused the opposite trends. The bacterial generalists utilizing aromatic backbone and labile C were mainly from Oxalobacteraceae (Proteobacteria) and Sporosarcina (Firmicutes). The bacterial specialists responsive for aromatic backbone were from Myxococcaceae and Flavisolibacter, while those responsive to labile C were from Ktedonobacteraceae and Bradyrhizobiaceae. Microbial abundance of specialists responsive to labile C was 3.3 times larger than those responsive to aromatic backbone, indicating the preferences of labile C specialists for energy sources and aromatic C specialists for slow utilization of persistent C in versatile habitats. Our work revealed microbial strategies for utilization of organic substances of very contrast availability, and their contributions to soil C sequestration depending on biochar components.
The release of organic compounds from plant roots (rhizodeposits) and their subsequent utilization by soil microbial communities is a key process linking atmospheric and terrestrial carbon (C) and nutrient cycling. However, the effects of land-use types on rhizodeposit-mediated alteration of microbial community structure and its consequences for soil C cycle are still, largely, unknown. Therefore, we used ¹³C-PLFA-SIP to evaluate the rhizosphere C fluxes to microorganisms in a monoculture crop (oilseed rape, Brassica napus L.), a mixed grassland (dominated by Lolium perenne L. mixed with clover Trifolium repens L.), and a tree (willow, Salix schwerinii E.L. Wolf and Salix viminalis L.) within an agroforestry system. Though harboring similar total microbial biomass, less ¹³C was recovered in microorganisms in soil under willow (0.017 % of ¹³C input) after 14 days as compared to rape (0.03 %) and grassland (0.09 %). Across three land use types, gram negative bacteria incorporated most of the ¹³C (28–42 % of total ¹³C labeled PLFAs), followed by fungi and gram positive bacteria (12–18 %) and less abundance groups (e.g. actinomycetes, <5 %). The arbuscular mycorrhizal fungal biomarker 16:1ω5c was enriched with ¹³C in soil under grassland (8 % of total ¹³C labeled PLFAs). The ¹³C incorporation into gram positive bacteria was higher in soil under willow than under grassland and rape. By contrast, 42 % of total ¹³C labeled PLFAs were attributed to gram negative bacteria in soil under rape. Overall, our results demonstrated that pronounced differences in microbial community structure and subsequent microbial C utilization between land-use types could affect soil C cycles and storage.
This study aims to elucidate the effect of Multi-Stage HTL with a constant resident time of 30 min for three different feedstocks including kitchen wastewater sludge (KwWs), freshwater microalgae Chlorella sorokiniana (UUIND6), Co-HTL (KwWs + UUIND6) to obtain the maximum bio-oil yield. According to the results obtained, KwWs appears to be the most suitable for conversion into energy-dense bio-oil under a sustainable biorefinery approach for increased bio-oil yields i.e., 72.75 ± 0.37 wt%, with HHV of 40.52 MJ/kg and energy recovery of 53.64 wt%. Further, the bio-oils and bio-chars derived from different types of biomasses obtained at different temperature conditions were analyzed by GC–MS, NMR, FTIR, and Raman spectroscopy to identify variations in the bio-crude compounds.
Nutrient acquisition strategies of plants regulate water flow and mass transport within ecosystems, shaping earth surface processes. Understanding plant strategies under current conditions is important to assess and predict responses of natural ecosystems to future climate and environmental changes. Nitrogen (N) and potassium (K) (re-)utilization from topsoil and their acquisition from subsoil and saprolite were evaluated in a continental transect, encompassing three study sites – an arid shrubland, a mediterranean woodland, and a temperate rainforest – on similar granitoid parent material in the Chilean Coastal Cordillera. The short-term (<1 year) plant N and K acquisition was traced with ¹⁵N and the K analogs rubidium and cesium. To do so, the tracers were either injected into topsoil, subsoil, or saprolite, in the immediate vicinity of eight individual plants per study site and injection depth. The long-term (>decades) K uplift by plants was investigated by the vertical distribution of exchangeable K⁺ and Na⁺. Recoveries of ¹⁵N and K analogs by arid shrubland plants were similar from topsoil, subsoil, and saprolite. Mediterranean woodland shrubs recovered the tracers primarily from topsoil (i.e., 89 % of recovered ¹⁵N and 84 % of recovered K analogs). Forest plants recovered the tracers from topsoil (¹⁵N = 49 %, K analogs = 57 %) and partially from greater depth: 38 % of recovered ¹⁵N and 43 % of recovered K analogs were acquired from subsoil and saprolite, respectively. Low nutrient accessibility in the topsoil (e.g., because of frequent droughts) drives shrubland plants to expand their N and K uptake to deeper and moister soil and saprolite. Woodland and forest plants dominantly recycled nutrients from topsoil. In the forest, this strategy was complemented by short-term uplift of N and K from depth. The vertical distribution of exchangeable K indicated long-term uplift of K by roots in all three sites. This highlighted that long-term K uplift from depth complements the nutrient budget across the continental transect.
We consider the algebra A of bounded operators on L2(Rn) generated by quantizations of isometric affine canonical transformations. The algebra A includes as subalgebras noncommutative tori of all dimensions and toric orbifolds. We define the spectral triple (A,H,D) with H=L2(Rn,Λ(Rn)) and the Euler operator D, a first order differential operator of index 1. We show that this spectral triple has simple dimension spectrum: For every operator B in the algebra Ψ(A,H,D) generated by the Shubin type pseudodifferential operators and the elements of A, the zeta function ζB(z)=Tr(B|D|−2z) has a meromorphic extension to C with at most simple poles. Our main result then is an explicit algebraic expression for the Connes-Moscovici cocycle. As a corollary we obtain local index formulae for noncommutative tori and toric orbifolds.
IgG Fc fragments that expose regulatory rheumatoid factor epitopes (regRF epitopes) have emerged as a promising immunosuppressive drug. Immunization of rats with such Fc fragments reduced symptoms of experimental autoimmune diseases. The immunosuppressive effect of Fc fragments is based on stimulating the production of regRF, which kills activated CD4 T lymphocytes. The formation of regRF epitopes on Fc fragments was previously shown to be associated with a reduction in disulfide bonds in the fragments’ hinge region. However, the structure of Fc fragments that bear regRF epitopes remained largely unclear. Infrared spectra were compared for lyophilized Fc fragments displaying regRF epitopes and Fc fragments without such epitopes. FTIR spectroscopy found no differences in the amide I, amide II, and amide III bands, indicating that there are no distinctive features in the secondary structure of Fc fragments bearing regRF epitopes. The distinctive feature of Fc fragments bearing regRF epitopes, irrespective of whether the free SH groups in the hinge were preserved or lost after lyophilization, is the presence of a band or a fine structure in the region containing the bending vibrations of the SH groups. Furthermore, the Fc fragments with regRF epitopes differ from those without in that they have a band in the absorption region of aromatic amino acid rings. Taken together, these facts suggest that the appearance of regRF epitopes results from changes in the tertiary structure of the hinge and the domains that occur when the hinge is reduced, and they also indicate that these conformational changes are resistant to subsequent changes in the state of cysteine residues in the hinge. Bands in the regions of aromatic amino acids and the bending vibrations of SH groups are markers of the presence of regRF epitopes on IgG Fc fragments. FTIR spectroscopy can be used to detect these epitopes.
Reclamation has been widely used to alleviate the degradation of cultivated upland and support the increasing grain demand. However, the response of soil ecosystem functioning and soil health to the reclamation of coastal wetlands remains unclear. A reclaimed soil chronosequence over 1000 years in Hangzhou Bay, China, was analyzed to assess two key approaches to evaluate soil health. We used the minimum data set along with the soil quality index (SQI) area and the sensitivity–resistance approaches. The physicochemical properties of the reclaimed soils changed drastically at the initial stage (during the first 60 years) but only marginally thereafter. Owing to continuous freshwater irrigation, plant cultivation, fertilization, and desalination, from natural tidal flats converted to vegetable fields, the SQI and soil multifunctional index increased along the reclamation chronosequence. The soil properties sensitive to the reclamation of coastal wetlands (electrical conductivity, exchangeable potassium, and enzyme activities) explained most of the variation in the SQI area, followed by the resistance indicators. This suggests that small changes in the sensitivity indicators might have considerable impacts on the improvement of soil quality. The most resistant properties with the slowest changes included pH and physical characteristics—water content, bulk density, and aggregate size classes. The quality indicators identified for reclaimed soils in Hangzhou Bay based on the SQI area and sensitivity–resistance approaches can be useful for soil health evaluation for soils affected by natural and anthropogenic factors. These approaches and indicators can be effectively used to evaluate soil quality and develop sustainable agriculture.
Potentially toxic heavy metals commonly exist in industrial wastewaters, presenting a critical global health threat to human health and environment, therefore, making their treatment is more challenging. In this study, an attractive polymer composite (CS-EDTA) adsorbent was developed by immobilization of ethylenediaminetetraacetic acid (EDTA) onto chitosan (CS) through cross-linking for the adsorptive removal of multiple heavy metals from industrial wastewater. The adsorption of heavy metals, i.e., Pb(II), Cd(II), and Cu(II) onto the developed composite was investigated by performing batch experiments with varying contact time and metal ion concentration in the mono-component system. The adsorption data fitted to the monolayer Langmuir isotherm; the maximum adsorption capacities were calculated as 370.37 ± 14.26, 243.90 ± 12.47, and 227.27 ± 15.33 mg g⁻¹ for Pb(II), Cd(II), and Cu(II), respectively. The kinetics of the adsorption followed the pseudo-second order (PSO) models, and obtained the rate constant values of 0.009 ± 0.0004, 0.001 ± 0.0001, and 0.0007 ± 0.0001 g mg⁻¹ min⁻¹ for Pb(II), Cd(II), and Cu(II), respectively. The adsorption of the heavy metals was attributed to the electrostatic interactions between the metals and different functional groups (OH, NH2, and COOH) of the adsorbent and complexation with EDTA, which was confirmed by the elemental mapping, EDS and FT-IR techniques. The reusability of the polymer composite was also tested and obtained >92 % efficiency even after five consecutive adsorption-desorption cycles which clearly demonstrating the high stability of the adsorbent. Lastly, the developed polymer composite was applied for real industrial wastewater. Excellent removal efficiencies (>84 %) were obtained, which makes it a potential candidate for the removal of heavy metals from real industrial wastewater.
The evolution of 6TiSCH networks is greatly increasing in the field of IIoT which supports reliable communication in IIoT environments. However, there is a lot of research gaps in the field of IIoT using 6TiSCH networks in terms of high latency, more energy consumption which degrades the overall performance of the IIoT environment. To address the above limitation in existing IIoT 6TiSCH approaches, an Edge-assisted 6TiSCH network for IIoT is proposed to overcome the above challenges such as Low latency and more energy consumption by efficient task scheduling and edge offloading considering risk in IIoT environment. The proposed work consists of three layers namely the 6TiSCH layer, Edge layer, and Cloud layer. In the 6TiSCH layer, initially, devices are registered by their credentials and authenticated by TA using Enhanced Advanced Encryption Standard (EAES) which reduces the unwanted energy consumption and latency by dropping the malicious devices. After authentication, only the verified devices are allowed for network construction using CORONA-based DODAG construction for selecting optimal parent which reduces the energy consumption. The optimal parent is selected by using Red Colobuses Monkey (RCM) optimization algorithm. Then two-level task scheduling is done namely Slot frame length optimization using Stochastic Gradient Descent (SGD) algorithm and adaptive partitioning using XG boost algorithm. In the Edge layer, effective offloading is done by using the Soft Actor-Critic (SAC) algorithm for reducing the energy consumption during offloading. Finally, all the processed data are sent to the cloud layer for access. The proposed work is experimented with using the Cooja simulation tool with Contiki 3 OS. The performance of the proposed work is compared to the existing works in terms of Latency (42 ms-20.4 ms) low, energy consumption (28.8 J-12 J) low in 6TiSCH layer, Latency (40 ms-20.4 ms) low, energy consumption (24.8 J-13.6 J) low in Edge layer, and overall comparison achieves throughput (508.8Kbps-322Kbps) high, packet delay ratio (8 %-4.6 %) high, end-to-end delay (6 s-9 s) low and efficiency (14.6 %-7.8 %) high. The experimental results show that our proposed work performs well than existing works.
Liquid transportation biofuel production is a promising strategy to reduce greenhouse gas emissions. Hydrothermal gasification (HTG) has shown great potential as an effective method for valorizing wet biomass. The high-quality syngas produced using the HTG process can be chemically/biochemically converted to liquid biofuels. Therefore, this paper aims to comprehensively review and critically discuss syngas production from biomass using the HTG process and its conversion into liquid biofuels. The basics and mechanisms of biomass HTG processing are first detailed to provide a comprehensive and deep understanding of the process. Second, the effects of the main operating parameters on the performance of the HTG process are numerically analyzed and mechanistically discussed. The syngas cleaning/conditioning and Fischer-Tropsch (FT) synthesis are then detailed, aiming to produce liquid biofuels. The economic performance and environmental impacts of liquid biofuels using the HTG-FT route are evaluated. Finally, the challenges and prospects for future development in this field are presented. Overall, the maximum total gas yield in the HTG process is obtained at temperature, pressure, and residence time in the range of 450–500 °C, 28–30 MPa, and 30–60 min, respectively. The highest C5+ liquid hydrocarbon selectivity in the FT process is achieved at temperatures between 200 and 240 °C. Generally, effective conversion of biomass to syngas using the HTG process and its successful upgrading using the FT process can offer a viable route for producing liquid biofuels. Future studies should use HTG technology in the biorefinery context to maximize biomass valorization and minimize waste generation.
We consider fully symmetric quadrature rules with positive weights, and with nodes lying inside the 3,…,6 dimensional simplex (so-called PI-type). PI-type fully symmetric quadrature rules up to 20-th order on the tetrahedron, 16-th order on 4-simplex, 10-th order on 5- and 6-simplexes are presented. The number of nodes of the presented quadrature rules for the corresponding orders does not exceed the known ones, and most of them are new. In the calculation we applied the modified Levenberg-Marquardt methods for solving nonlinear equations with convex constraints. The corresponding programs are implemented in MAPLE-FORTRAN environment, and the weights and nodes are first calculated using a FORTRAN program with an accuracy of 10−25 and refined up to accuracy of 10−50 using a MAPLE program.
The leakage, caused by design problems, pipe breakage, and fittings' failure, is a critical challenge that the beneficiaries face in the water distribution networks (WDNs). Control and management of the network pressure have always been considered helpful solutions to reduce the leakage in these systems. In the present study, locating and setting of the five pressure reducer valves (PRVs) have been optimized using GA (genetic algorithm) to minimize the leakage and make uniform pressure. Results show that the network leakage has reduced 21% from 34.53 lit/s to 27.26 lit/s. In the next step, the PRVs are replaced by two pumps as turbines (PATs) at two desirable points for converting extra elevation head of the real gravity WDN to generate electricity. It is also found that the performance of PATs in reducing the amount of leakage is similar to PRV, and there are slight differences. Therefore, nearly 153 MW/year is generated using two PATs that resulted in 15,000 $/year in cost-saving. As estimated, the cost for installing and operating two PATs is $14,000, so the return on capital will be at least one year.
- K.A. Dokukina
- V.V. Khiller
- V.B. Khubanov
- M.A. Yakushik
Eclogites exposed along the northeastern boundary of the Belomorian orogen in the eastern Fennoscandian Shield formed as a result of Mesoarchean–Neoarchean subduction. Highly-deformed banded TTG gneisses with eclogitized mafic pods, lenses and dykes in the Gridino association of metamorphic rocks have been modified locally to have typical migmatite structures that formed as HP rocks decompressed through HP granulite-facies metamorphic conditions (16–12 kbar, 800–850 °C) to amphibolite-facies conditions (10–9 kbar, 600–700 °C). The migmatites are located with the boundaries between felsic and mafic lithologies, which are the most suitable place for partial melting, fluid migration, and component diffusion. Symplectic intergrowths of hydrous minerals (mica, epidote) together with quartz in the leucosome are important markers of arrested reaction textures that formed by reversed hydration crystallization of residual melts or by fluids where their infiltrated through migmatite areas. There are two potassic granitic leucosomes with contrasting geochemical signatures. Garnet and phengite-bearing leucosome replaces the host TTG gneiss and percolates mafic rocks. This leucosome is distinguished by a high Ba content, striking positive Eu and Sr anomalies and corresponding low concentrations of all other trace elements. The compositions of the leucosome record initial segregation and migration of melt away from the residual source and subsequent crystal fractionation, dominated by feldspars, of the escaped melt. Migration of anatectic melts led to the formation of small bodies of leucogranite that are characterized by high contents of trace elements and negative Eu and Sr anomalies. Leucogranites formed from portions of fractionated melt that percolated the migmatites and solidified. Anatexis occurred during the Neoarchean time (∼2.7 Ga). U-rich zircon domains were partly or completely affected by radiation damage that yield discordant scattered dates between 2.7 and 1.9 Ga, which are interpreted as reflecting a thermal and fluid overprint during evolution of Belomorian province that produced recrystallization and Pb loss in Neoarchean zircons.
Organic matter input regulates the rate and temperature sensitivity (expressed as Q 10) of soil organic matter (SOM) decomposition by changing microbial composition and activities. It remains unclear how the incorporation of litter-made biochar instead of litter affects the Q 10 of SOM decomposition. Using a unique combination of two-and three-source partitioning methods (isotopic discrimination between C3/C4 pathways and 14 C labeling), we investigated: (1) how maize litter versus litter-made biochar (of C4 origin) addition influenced the Q 10 of SOM (C3 origin) under 10°C warming, and (2) how the litter or biochar amendments affected the Q 10 of 14 C-labeled fresh organic matter (FOM) after long-term incubation. Compared with biochar addition, litter increased the rates and Q 10 of mass-specific respiration, SOM and FOM decomposition, as well as the contents of SOM-derived dissolved organic C (DOC) and total phospholipid fatty acids (PLFA). Litter-amended soils have much higher activities (V max) of β-glucosidase, N-acetyl-β-glucosaminidase, and leucine aminopeptidase, suggesting larger enzyme pools than in soils with biochar. The Q 10 of enzyme V max (1.6-2.0) and K m (1.2-1.4) were similar between litter-and biochar-amended soils, and remained stable with warming. However, warming reduced microbial biomass (PLFA) and enzyme activity (V max), suggesting decreased enzyme production associated with smaller microbial biomass or faster enzyme turnover at higher temperatures. Reductions in PLFA content and enzyme V max due to warming were larger in litter-amended soils (by 31%) than in the control and biochar-amended soils (by 4-11%), implying the active litter-feeding microorganisms have a smaller degree of heat tolerance than the inactive microorganisms under biochar amendments. The reduction in enzyme activity (V max) by warming was lower in soils with biochar than in the control soil. Our modeling suggested that the higher Q 10 in litter-amended soils was mainly caused by faster C loss under warming, linked to (2022) Contrasting effects of maize litter and litter-derived biochar on the temperature sensitivity of paddy soil organic matter decomposition. Frontiers in Microbiology 02 frontiersin.org reductions in microbial biomass and growth efficiency, rather than the slightly increased SOM-originated substrate availability (DOC). Overall, using straw-made biochar instead of straw per se as a soil amendment lowers the Q 10 of SOM and FOM by making microbial communities and enzyme pools more temperature-tolerant, and consequently reduces SOM losses under warming.
Due to the increasing environmental pollution caused by human activities, environmental remediation has become an important subject for humans and environmental safety. The quest for beneficial pathways to remove organic and inorganic contaminants has been the theme of considerable investigations in the past decade. The easy and quick separation made magnetic solid-phase extraction (MSPE) a popular method for the removal of different pollutants from the environment. Metal−organic frameworks (MOFs) are a class of porous materials best known for their ultrahigh porosity. Moreover, these materials can be easily modified with useful ligands and form various composites with varying characteristics, thus rendering them an ideal candidate as adsorbing agents for MSPE. Herein, research on MSPE, encompassing MOFs as sorbents and Fe3O4 as a magnetic component, is surveyed for environmental applications. Initially, assorted pollutants and their threats to human and environmental safety are introduced with a brief introduction to MOFs and MSPE. Subsequently, the deployment of magnetic MOFs (MMOFs) as sorbents for the removal of various organic and inorganic pollutants from the environment is deliberated, encompassing the outlooks and perspectives of this field.
Malic acid (MA) is one of the organic acids that has been less studied for its effects on fish growth performance and gut health. The present study aimed to assess the effects of dietary MA supplementation on growth performance, antioxidant and immunological parameters, and intestinal gene expressions in rainbow trout, Oncorhynchus mykiss. Fish with ~25 g body weight were randomly distributed into 12 tanks at a density of 15 fish per tank and were fed with diets containing 0 (control), 0.25, 0.5, and 1% MA over 8 weeks. The results indicated that dietary MA persuaded no significant changes in growth performance and survival rate. There were elevations in serum alanine aminotransferase (ALT; 0.5 and 1% MA), aspartate aminotransferase (AST; 0.5 and 1% MA), lysozyme (0.25, 0.5 and 1% MA), catalase (CAT; 0.5 and 1% MA), superoxide dismutase (SOD; 1% MA), glutathione peroxidase (GPx; 0.25 and 0.5% MA) activities, and total immunoglobulin (Ig) level (0.5% MA) in the fish MA-supplemented diets, compared to the control. Serum alkaline phosphatase (ALP) activity showed a decrease in 0.5% MA treatment compared to the control. Skin mucus lysozyme (0.25% MA), alternative complement activity (ACH50; 0.5% MA), and total Ig (0.25 and 0.5% MA) showed significant elevations, whereas skin mucus ALP (0.5% MA) exhibited a significant decrease in MA-treated fish, compared to the control fish. Intestinal il-1β (0.5 and 1% MA), hsp70 (0.5% MA), tnf-α (0.5% MA), tgf-β (1% MA), caspase 3 (1% MA), and caspase 9 (1% MA) expressions significantly increased in M-treated fish, compared to the control. In conclusion, this study showed that dietary inclusion of malic acid at the rate of 0.25% in O. mykiss diets improved the antioxidant status and immune responses of fish without any negative effect on growth performance.
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