Soybean molasses can be used as a substitute for corn in grazing beef cattle supplements during the rainy season.

Soybean molasses (SBMO) is a byproduct derived from the production of soy protein concentrate, obtained through solubilization in water and alcohol. The utilization of SBMO as an animal feed ingredient shows promising potential, primarily due to its low cost and as a potential energy concentrate. This study aimed to assess the intake, digestibility, ruminal parameters (pH and ruminal ammonia - NH3), nitrogen retention (NR) and microbial protein synthesis in grazing beef cattle supplemented with SBMO as a substitute for corn during the rainy season. Five Nellore (10-month-old) bulls with an average initial weight of 246 ± 11.2 kg were utilized in a 5 × 5 Latin square design. The animals were housed in five paddocks, each consisting of 0.34 ha of Marandu grass (Urochloa brizantha). Five isonitrogenous protein-energy supplements (300 g crude protein [CP]/kg supplement) were formulated, with SBMO replacing corn at varying levels (0, 0.25, 0.50, 0.75, or 1.00 g-1 g). The supplements were provided daily at a quantity of 2.0 kg-1 animal. The inclusion of SBMO at any level of corn substitution did not significantly affect the intake of pasture dry matter or total dry matter (P > 0.10). Likewise, the intake of CP and, consequently, the ruminal concentration of NH3 did not differ among the SBMO levels. Increasing the inclusion of SBMO did not have a significant impact on NR (P > 0.10), indicating that animals receiving supplements containing 100% SBMO as a substitute for corn may perform similarly to animals receiving supplements with 100% corn (0% SBMO). Soybean molasses represents a viable alternative energy source for grazing beef cattle during the rainy season and can entirely replace corn without adversely affecting animal nutritional performance.

Efficient trihalomethane quantification in drinking water for minimally-equipped water treatment plants labs.

Chlorine is a common disinfectant used in water treatment. However, its reaction with organic matter can lead to the formation of harmful byproducts, such as trihalomethanes (THMs), which are potentially carcinogenic. To address this issue, the aim of this work was to enhance a colorimetric method capable of quantifying THMs in drinking water through UV/Vis Spectrophotometry, using cost-effective equipment, and validate this methodology for the first time according to established validation protocols. The method's innovation involved replacing the solvent pentane with the more common hexane, along with adjusting the heating ramp, elucidating the mechanisms involved in the process. This method involves the reaction between THMs, pyridine, and NaOH to produce a colored compound, which is then monitored through molecular absorption spectroscopy in the visible region. The method was thoroughly validated, achieving a limit of detection of 13.41 µg L-1 and a limit of quantification of 40.65 µg L-1. Recovery assays ranged from 86.1 % to 90.7 %, demonstrating high accuracy. The quality of the linear fit for the analytical curve exceeded R2 > 0.98. The method was applied to real samples, revealing concentrations ranging from 13.58 to 55.46 µg L-1, all way below the legal limit in Brazil (Maximum Contaminant Levels (MCL) = 100 µg L-1). This cost-effective and straightforward method is suitable for integration into water treatment plant laboratories.

Updates in inspiratory muscle training for older adults: A systematic review.

Systematic reviews support the benefits of inspiratory muscle training (IMT) for exercise performance. Recently, many health benefits from IMT have been reported in older adults. Therefore, this work reviewed the literature focusing on IMT effects beyond physical performance in older adults, such as cardiorespiratory, metabolic, and postural balance outcomes. Searches were conducted with the following terms: ("respiratory muscle training" OR "inspiratory muscle training") OR ("inspiratory muscle strength training") AND ("elderly" OR "older" OR "aging" OR "aging"), and using the databases: MEDLINE (PubMed), SCOPUS and EUROPE PMC. Of the 356 articles found, 13 matched the inclusion criteria after screening. Based on reviewed studies, four to eight weeks of IMT (Mostly from 50 % up to 75 % of MIP, 7 days/week) improve cardiac autonomic control at rest and post-exercise, cerebrovascular response to orthostatic stress, static and dynamic balance, blood pressure control, endothelial function, and oxidative stress in older adults. The benefits of IMT in cardiac autonomic and vascular functions are reversed after training cessation. It thus appears that IMT promotes broad physiological gains for the older population. It is necessary to carry out more randomized clinical trials on the subject to confirm the findings of this research.

Clinical and molecular characterization of limb-girdle muscular dystrophy 2G/R7 in a large cohort of Brazilian patients.

Limb-girdle muscular dystrophy type 2G/R7 (LGMD2G/R7) is an ultra-rare condition initially identified within the Brazilian population. We aimed to expand clinical and genetic information about this disease, including its worldwide distribution. A multicenter historical cohort study was performed at 13 centers in Brazil in which data from index cases and their affected relatives from consecutive families with LGMD2G/R7 were reviewed from July 2017 to August 2023. Additionally, a systematic literature review was conducted to identify case reports and series of the disease worldwide. Forty-one LGMD2G/R7 cases were described in the Brazilian cohort, being all subjects homozygous for the c.157C>T/(p.Gln53*) variant in TCAP. Survival curves showed that the median disease duration before individuals required walking aids was 21 years. Notably, women exhibited a slower disease progression, requiring walking aids 13 years later than men. LGMD2G/R7 was frequently reported not only in Brazil but also in China and Bulgaria, with 119 cases identified globally, with possible founder effects in the Brazilian, Eastern European, and Asian populations. These findings are pivotal in raising awareness of LGMD2G/R7, understanding its progression, and identifying potential modifiers. This can significantly contribute to the development of future natural history studies and clinical trials for this disease.

Action of dithiocarbimates salts on the honey bee and its pathogen Nosema ceranae.

Apis mellifera, crucial pollinators for both native and cultivated plants, also yield various products such as honey, wax, royal jelly, and propolis, extensively utilized in the food, pharmaceuticals, and cosmetics industries. Nosema ceranae, a prevalent microsporidian worldwide, stands as a significant pathogen for A. mellifera, showing resistance to conventional antibiotics. Consequently, the exploration of novel compounds for N. ceranae control becomes imperative. Dithiocarbimate derivatives emerge as promising antifungal candidates under evaluation for combating various pathogens, particularly those affecting plants. This study assessed the toxicity profile of six dithiocarbimate derivatives on A. mellifera worker survival and N. ceranae pathogen. Among these, four compounds exhibited minimal bee mortality and proceeded to further evaluation against N. ceranae. In vitro assays demonstrated their inhibitory effects on spore germination. Remarkably, the most potent compound suppressed N. ceranae spores by 62% at a concentration of 20 µmol L-1in vivo. Thus, these dithiocarbimate derivatives represent promising new antifungal agents for combatting nosemosis in honey bee populations.

The Relationship between Inspiratory Muscle Strength and Cycling Performance: Insights from Hypoxia and Inspiratory Muscle Warm-Up.

Hypoxia increases inspiratory muscle work and consequently contributes to a reduction in exercise performance. We evaluate the effects of inspiratory muscle warm-up (IMW) on a 10 km cycling time trial in normoxia (NOR) and hypoxia (HYP). Eight cyclists performed four time trial sessions, two in HYP (FiO2: 0.145) and two in NOR (FiO2: 0.209), of which one was with IMW (set at 40% of maximal inspiratory pressure-MIP) and the other was with the placebo effect (PLA: set at 15% MIP). Time trials were unchanged by IMW (NORIMW: 893.8 ± 31.5 vs. NORPLA: 925.5 ± 51.0 s; HYPIMW: 976.8 ± 34.2 vs. HYPPLA: 1008.3 ± 56.0 s; p > 0.05), while ventilation was higher in HYPIMW (107.7 ± 18.3) than HYPPLA (100.1 ± 18.9 L.min-1; p ≤ 0.05), and SpO2 was lower (HYPIMW: 73 ± 6 vs. HYPPLA: 76 ± 6%; p ≤ 0.05). A post-exercise-induced reduction in inspiratory strength was correlated with exercise elapsed time during IMW sessions (HYPIMW: r = -0.79; p ≤ 0.05; NORIMW: r = -0.70; p ≤ 0.05). IMW did not improve the 10 km time trial performance under normoxia and hypoxia.

Photogrammetry scans for neuroanatomy education - a new multi-camera system: technical note.

Photogrammetry scans has directed attention to the development of advanced camera systems to improve the creation of three-dimensional (3D) models, especially for educational and medical-related purposes. This could be a potential cost-effective method for neuroanatomy education, especially when access to laboratory-based learning is limited. The aim of this study was to describe a new photogrammetry system based on a 5 Digital Single-Lens Reflex (DSLR) cameras setup to optimize accuracy of neuroanatomical 3D models. One formalin-fixed brain and specimen and one dry skull were used for dissections and scanning using the photogrammetry technique. After each dissection, the specimens were placed inside a new MedCreator® scanner (MedReality, Thyng, Chicago, IL) to be scanned with the final 3D model being displayed on SketchFab® (Epic, Cary, NC) and MedReality® platforms. The scanner consisted of 5 cameras arranged vertically facing the specimen, which was positioned on a platform in the center of the scanner. The new multi-camera system contains automated software packages, which allowed for quick rendering and creation of a high-quality 3D models. Following uploading the 3D models to the SketchFab® and MedReality® platforms for display, the models can be freely manipulated in various angles and magnifications in any devices free of charge for users. Therefore, photogrammetry scans with this new multi-camera system have the potential to enhance the accuracy and resolution of the 3D models, along with shortening creation time of the models. This system can serve as an important tool to optimize neuroanatomy education and ultimately, improve patient outcomes.

Associative Bacteria and Arbuscular Mycorrhizal Fungus Increase Drought Tolerance in Maize (Zea mays L.) through Morphoanatomical, Physiological, and Biochemical Changes.

Water deficiency has been recognized as a major abiotic stress that causes losses in maize crops around the world. The maize crop is very important due to the range of products that are derived from this plant. A potential way to reduce the damages caused by water deficiency in maize crops is through the association with plant growth-promoting bacteria (PGPB) and arbuscular mycorrhizal fungi (AMF). To define the mechanisms developed by associative PGPB and AMF in maize that are involved in protection against moderate drought (MD), this study evaluated the biometrical, anatomical, biochemical, and physiological parameters of maize grown under MD and inoculated with different PGPB (Azospirillum brasilense strain Ab-V5 and Bacillus sp. strain ZK) and with AMF. The relative water content did not change in the treatments. The association with ZK increased the shoot:total ratio, total dry weight, maximum quantum yield of photosystem II, vascular cylinder thickness, and vascular cylinder area. The Ab-V5 inoculation led to an increment in root dry weight, the area of metaxylem vessel elements, and nitrate reductase activity. The AMF association did not lead to changes in the measured parameters. The results indicate that the association with PGPB is a relevant alternative to contribute to reducing losses in maize crops under drought. However, AMF is not indicated for this crop under drought.

Influence of plant growth-promoting bacteria on leaf carbon and nitrogen metabolism of two drought-stressed neotropical tree species: a metabolomic approach.

Deforestation of Atlantic Forest has caused prolonged drought events in the last decades. The need for reforestation is growing, and the development of native seedlings that are more tolerant to drought stress is necessary. A biotechnological tool that improves plant tolerance is the use of plant growth-promoting bacteria (PGPB) as inoculants. Two species of PGPB were inoculated in drought-stressed seedlings of two neotropical tree species that have been used in environmental restoration programs: Cecropia pachystachya and Cariniana estrellensis. Biometrical, physiological, and metabolomic parameters from carbon and nitrogen pathways were evaluated. We found that the PGPB positively influenced photosynthesis and growth parameters in both trees under drought. The enzymes activities, the tricarboxylic acid cycle intermediates, the amino acids, and protein contents were also influenced by the PGPB treatments. The results allowed us to find the specific composition of secondary metabolites of each plant species. This study provides evidence that there is not a single mechanism involved in drought tolerance and that the inoculation with PGPB promotes a broad-spectrum tolerance response in Neotropical trees. The inoculation with PGPB appears as an important strategy to improve drought tolerance in Atlantic Forest native trees and enhance environmental restoration programs' success. MAIN CONCLUSION: The association with plant growth-promoting bacteria improved the tolerance to drought in Neotropical trees through biochemical, physiological, and biometrical parameters. This can enhance the success of forest restoration programs.

Burden of liver disease in Brazil, 1996-2022: a retrospective descriptive study of the epidemiology and impact on public healthcare.

Background: Liver disease is a major cause of mortality and morbidity worldwide and its epidemiology depends on the genetic background, exposure to risk factors, access to healthcare and other sociodemographic characteristics. Brazil is a large country with diverse multicultural and ethnic heritages and important socioeconomic inequalities. The burden of liver disease in Brazil, its regions and population is unknown. Methods: We retrieved data from the Unified Health System regarding liver diseases and analyzed the mortality and morbidity from 1996 to 2022 by gender, race/ethnicity, age, region and overall. We calculated the age-specific risk of deaths by liver disease, age-standardization of the data, mean hospitalization and liver transplant-associated costs. Findings: Malignant neoplasm of the liver and intrahepatic bile ducts, alcohol-associated liver disease, fibrosis, and cirrhosis of the liver, other diseases of the liver, hepatic failure, chronic viral hepatitis were identified as the major causes of death and morbidity in Brazil in the period analyzed. The epidemiology of these diseases was diverse, with variations according to geographic regions, gender and race/ethnicity. The major economic burden of liver disease is related to liver transplants, a common outcome of the progression of these diseases. Interpretation: Liver disease in Brazil is a serious issue for the public health system due to the high number of deaths and increasing mortality rate. Our study contributes as a necessary prerequisite for the development of tailored public health policies aimed at mitigating the increasing burden of liver diseases in specific populations and regions. Funding: CNPq, INCT, CAPES, FAPEMIG.

Forensic Geochemistry Reveals International Ship Dumping as a Source of New Oil Spill in Brazil's Coastline (Bahia) in Late 2023.

In the present study, we applied forensic geochemistry to investigate the origin and fate of spilled oils like tarballs stranded at the beaches of Bahia, in northeastern Brazil, in September 2023, based on their fingerprints. Saturated and aromatic compounds were assessed by gas chromatography, and the oceanic surface circulation patterns were deciphered to determine the geographic origin of the spill. Contamination by petroleum represents an enormous threat to the unique, species-rich ecosystems of the study area. The geochemical fingerprint of the oil spilled in 2023 did not correlate with those of previous events, including the one in 2019, the one in early 2022 in Ceará, and an extensive spill across the Brazilian Northeast in late 2022. However, the fingerprint did correlate with crude oils produced by Middle Eastern countries, most likely Kuwait. The oil of the 2023 spill had a carbonate marine origin from early mature source rocks. These findings, together with the moderate weathering of the 2023 tarballs and the ocean circulation patterns at the time of the event, indicate that the oil was discharged close to the shore of Brazil, to the east or southeast of Salvador, by a tanker on an international route in the South Atlantic.

A comparative genomics study of the microbiome and freshwater resistome in Southern Pantanal.

This study explores the resistome and bacterial diversity of two small lakes in the Southern Pantanal, one in Aquidauana sub-region, close to a farm, and one in Abobral sub-region, an environmentally preserved area. Shotgun metagenomic sequencing data from water column samples collected near and far from the floating macrophyte Eichhornia crassipes were used. The Abobral small lake exhibited the highest diversity and abundance of antibiotic resistance genes (ARGs), antibiotic resistance classes (ARGCs), phylum, and genus. RPOB2 and its resistance class, multidrug resistance, were the most abundant ARG and ARGC, respectively. Pseudomonadota was the dominant phylum across all sites, and Streptomyces was the most abundant genus considering all sites.

Use of hormones and risk of venous thromboembolism.

•The risk of venous thromboembolism (VTE) is not increased in women using long-acting reversible contraceptive methods (LARCs) with progestogens. •Oral contraceptives with levonorgestrel or norgestimate confer half the risk of VTE compared to oral contraceptives containing desogestrel, gestodene or drospirenone. •Progestogen-only pills do not confer an increased risk of VTE. •Women using transdermal contraceptive patches and combined oral contraceptives (COCs) are at an approximately eight times greater risk of VTE than non-users of hormonal contraceptives (HCs), corresponding to 9.7 events per 10,000 women/years. •Vaginal rings increase the risk of VTE by 6.5 times compared to not using HC, corresponding to 7.8 events per 10,000 women/years. •Several studies have demonstrated an increased risk of VTE in transgender individuals receiving hormone therapy (HT). •Hormone therapy during menopause increases the risk of VTE by approximately two times, and this risk is increased by obesity, thrombophilia, age over 60 years, surgery and immobilization. •The route of estrogen administration, the dosage and type of progestogen associated with estrogen may affect the risk of VTE in the climacteric. •Combined estrogen-progesterone therapy increases the risk of VTE compared to estrogen monotherapy. •Postmenopausal HT increases the risk of thrombosis at atypical sites.

Signature of excitonic insulators in phosphorene nanoribbons.

Phosphorene is a recently developed two-dimensional (2D) material that has attracted tremendous attention because of its unique anisotropic optical properties and quasi-one-dimensional (1D) excitons. We use first-principles calculations combined with the maximally localized Wannier function tight binding Hamiltonian and Bethe-Salpeter equation (BSE) formalism to investigate quasiparticle effects of 2D and quasi-1D blue and black phosphorene nanoribbons. Our electronic structure calculations shows that both blue and black monolayered phases are semiconductors. On the other hand black phosphorene zigzag nanoribbons are metallic. Similar behavior is found for very thin blue phosphorene zig-zag and armchair nanoribbon. As a general behavior, the exciton binding energy decreases as the ribbon width increases, which highlights the importance of quantum confinement effects. The solution of the BSE shows that the blue phosphorene monolayer has an exciton binding energy four times higher than that of the black phosphorene counterpart. Furthermore, both monolayers show a different linear optical response with respect to light polarization, as black phosphorene is highly anisotropic. We find a similar, but less pronounced, optical anisotropy for blue phosphorene monolayer, caused exclusively by the quasi-particle effects. Finally, we show that some of the investigated nanoribbons show a spin-triplet excitonic insulator behavior, thus revealing exciting features of these nanoribbons and therefore provides important advances in the understanding of quasi-one dimensional phosphorus-based materials.

3D Models as a Source for Neuroanatomy Education: A Stepwise White Matter Dissection Using 3D Images and Photogrammetry Scans.

White matter dissection (WMD) involves isolating bundles of myelinated axons in the brain and serves to gain insights into brain function and neural mechanisms underlying neurological disorders. While effective, cadaveric brain dissections pose certain challenges mainly due to availability of resources. Technological advancements, such as photogrammetry, have the potential to overcome these limitations by creating detailed three-dimensional (3D) models for immersive learning experiences in neuroanatomy. This study aimed to provide a detailed step-by-step WMD captured using two-dimensional (2D) images and 3D models (via photogrammetry) to serve as a comprehensive guide for studying white matter tracts of the brain. One formalin-fixed brain specimen was utilized to perform the WMD. The brain was divided in a sagittal plane and both cerebral hemispheres were stored in a freezer at -20 °C for 10 days, then thawed under running water at room temperature. Micro-instruments under an operating microscope were used to perform a systematic lateral-to-medial and medial-to-lateral dissection, while 2D images were captured and 3D models were created through photogrammetry during each stage of the dissection. Dissection was performed with comprehensive examination of the location, main landmarks, connections, and functions of the white matter tracts of the brain. Furthermore, high-quality 3D models of the dissections were created and housed on SketchFab®, allowing for accessible and free of charge viewing for educational and research purposes. Our comprehensive dissection and 3D models have the potential to increase understanding of the intricate white matter anatomy and could provide an accessible platform for the teaching of neuroanatomy.

Concerted regulation of skeletal muscle metabolism and contractile properties by the orphan nuclear receptor Nr2f6.

BACKGROUND: The maintenance of skeletal muscle plasticity upon changes in the environment, nutrient supply, and exercise depends on regulatory mechanisms that couple structural and metabolic adaptations. The mechanisms that interconnect both processes at the transcriptional level remain underexplored. Nr2f6, a nuclear receptor, regulates metabolism and cell differentiation in peripheral tissues. However, its role in the skeletal muscle is still elusive. Here, we aimed to investigate the effects of Nr2f6 modulation on muscle biology in vivo and in vitro. METHODS: Global RNA-seq was performed in Nr2f6 knockdown C2C12 myocytes (N = 4-5). Molecular and metabolic assays and proliferation experiments were performed using stable Nr2f6 knockdown and Nr2f6 overexpression C2C12 cell lines (N = 3-6). Nr2f6 content was evaluated in lipid overload models in vitro and in vivo (N = 3-6). In vivo experiments included Nr2f6 overexpression in mouse tibialis anterior muscle, followed by gene array transcriptomics and molecular assays (N = 4), ex vivo contractility experiments (N = 5), and histological analysis (N = 7). The conservation of Nr2f6 depletion effects was confirmed in primary skeletal muscle cells of humans and mice. RESULTS: Nr2f6 knockdown upregulated genes associated with muscle differentiation, metabolism, and contraction, while cell cycle-related genes were downregulated. In human skeletal muscle cells, Nr2f6 knockdown significantly increased the expression of myosin heavy chain genes (two-fold to three-fold) and siRNA-mediated depletion of Nr2f6 increased maximal C2C12 myocyte's lipid oxidative capacity by 75% and protected against lipid-induced cell death. Nr2f6 content decreased by 40% in lipid-overloaded myotubes and by 50% in the skeletal muscle of mice fed a high-fat diet. Nr2f6 overexpression in mice resulted in an atrophic and hypoplastic state, characterized by a significant reduction in muscle mass (15%) and myofibre content (18%), followed by an impairment (50%) in force production. These functional phenotypes were accompanied by the establishment of an inflammation-like molecular signature and a decrease in the expression of genes involved in muscle contractility and oxidative metabolism, which was associated with the repression of the uncoupling protein 3 (20%) and PGC-1α (30%) promoters activity following Nr2f6 overexpression in vitro. Additionally, Nr2f6 regulated core components of the cell division machinery, effectively decoupling muscle cell proliferation from differentiation. CONCLUSIONS: Our findings reveal a novel role for Nr2f6 as a molecular transducer that plays a crucial role in maintaining the balance between skeletal muscle contractile function and oxidative capacity. These results have significant implications for the development of potential therapeutic strategies for metabolic diseases and myopathies.

Development of a green and low-cost method to determine mercury content in sediments affected by oil spill on the Brazilian coast.

Tons of crude oil were found on the Brazilian coast in 2019, and studies assessing its chemical composition are still scarce. This study aimed to develop a new and simple technique of cold vapor generation using infrared irradiation coupled with atomic absorption spectrometry to determine mercury content in sediments contaminated by crude oil. Experimental conditions were evaluated, including formic acid concentration, reactor temperature, and carrier gas flow rate. The accuracy of the method was validated by comparison with mercury contents in a certified reference material (PACS-2). The detection limit was found to be 0.44 µg kg-1. The developed method was applied to determine the total mercury content in marine sediment samples collected from beaches in Ceará State. Mercury concentrations ranged from 0.41 to 0.95 mg kg-1. The proposed method is efficient, simple, low-cost, and adequate for its purpose.

Essential oil and fenchone extracted from Tetradenia riparia (Hochstetter.) Codd (Lamiaceae) induce oxidative stress in Culex quinquefasciatus larvae (Diptera: Culicidae) without causing lethal effects on non-target animals.

We investigated the larvicidal activity of the essential oil (EO) from Tetradenia riparia and its majority compound fenchone for controlling Culex quinquefasciatus larvae, focusing on reactive oxygen and nitrogen species (RONS), catalase (CAT), glutathione S-transferase (GST), acetylcholinesterase (AChE) activities, and total thiol content as oxidative stress indicators. Moreover, the lethal effect of EO and fenchone was evaluated against Anisops bouvieri, Diplonychus indicus, Danio rerio, and Paracheirodon axelrodi. The EO and fenchone (5 to 25 µg/mL) showed larvicidal activity (LC50 from 16.05 to 18.94 µg/mL), followed by an overproduction of RONS, and changes in the activity of CAT, GST, AChE, and total thiol content. The Kaplan-Meier followed by Log-rank (Mantel-Cox) analyses showed a 100% survival rate for A. bouvieri, D. indicus, D. rerio, and P. axelrodi when exposed to EO and fenchone (262.6 and 302.60 µg/mL), while α-cypermethrin (0.25 µg/mL) was extremely toxic to these non-target animals, causing 100% of death. These findings emphasize that the EO from T. riparia and fenchone serve as suitable larvicides for controlling C. quinquefasciatus larvae, without imposing lethal effects on the non-target animals investigated.

Co3O4/activated carbon nanocomposites as electrocatalysts for the oxygen evolution reaction.

The Oxygen Evolution Reaction (OER) is crucial in various processes such as hydrogen production via water splitting. Several electrocatalysts, including metal oxides, have been evaluated to enhance the reaction efficiency. Zeolitic Imidazolate Framework-67 (ZIF-67) has been employed as a precursor to produce Co3O4, showing high OER activity. Additionally, the formation of composites with carbon-based materials improves the activity of these materials. Thus, this work focuses on synthesizing ZIF-67 and commercial activated carbon (AC) composites, which were used as precursors to obtain Co3O4/C electrocatalysts by calculating ZIF-67/CX (X = 10, 30, and 50, the mass percentage of AC). The obtained materials were thoroughly characterized by employing X-ray powder diffraction (XRD), confirming the cobalt oxide structure with a sphere-like morphology as observed in the TEM images. The presence of oxygen vacancies was confirmed by infrared spectroscopy and EPR measurements. The electrocatalytic performance in the OER was investigated by linear sweep voltammetry (LSV), which revealed an overpotential of 325 mV at 10 mA cm-2 and a Tafel slope value of 65.32 mV dec-1 for Co3O4/C10, superior in activity to several previously reported studies in the literature and electrochemical stability of up to 8 hours. The reduced value of charge transfer resistance, high double-layer capacitance, and the presence of Co3+ ions justify the superior performance of the Co3O4/C10 electrocatalyst.