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Gold cyanidation facilities in the Arequipa Region of Peru are challenged by the availability and quality of water for processing in an arid environment. The facilities reuse decant water which recycles residual cyanide but also undesirable constituents. To understand the impact of intensive water recycling on cyanide and metals concentrations, we collected barren water, decant water, and tailings samples from six gold cyanidation facilities with ore capacities of 10-430 tons per day. Processing facilities in Arequipa recycle all effluents, with decant waters making up 58 ± 11 % of process waters. Decant water contained non-target metals: copper (394 ± 161 mg/L), iron (59 ± 34 mg/L), and zinc (74 ± 42 mg/L). In addition, decant water mean free and complexed cyanide concentrations were 534 ± 129 mg/L and 805 ± 297 mg/L, respectively. Complexed cyanide concentrations remained more constant than free cyanide concentrations with 786 ± 299 mg/L for barren water and 805 ± 297 mg/L for decant water. Cyanide mass balances showed between 21 % and 42 % of unaccounted free cyanide from the start of gold cyanidation and discharge to the tailings storage facility (TSF). Free cyanide estimated losses due to volatilization were 0.8 kg and 2.5 kg of hydrogen cyanide per ton of ore processed at barren water pH of 10.1 and 9.7. Together these results indicate two acute hazards: 1) volatilization of free cyanide during processing and 2) loading and retention of cyanides and metals into TSFs. This study elucidates the extent of uncontrolled vapor phase cyanide release during gold processing operation and contaminant concentrations in the tailings storage facilities. The data highlights the need for improvement oversight, accountability, and regulation of gold processing facilities practicing intensive recycling and zero discharge.

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The recovery of gold by adsorption using activated carbon from sodium cyanide and thiourea leached solutions are reported in this study. The leached solutions were obtained under real operating conditions from the beneficiation plant "Paz Borja", Machala-Ecuador. Calgon Carbon DG-11 6X12 type, widely used in the local metallurgical industry was used as adsorbent material. The operational parameters varied during the adsorption process experiments included the concentration of leaching agent, agitation speed, dose of activated carbon and initial concentration of gold. The control parameters included density, percentage of solid, pH, temperature, and solution potential. The obtained results were adjusted to mass transfer model by diffusion through the interface and the Freundlich model for the equilibrium isotherms. The analysis of the results indicates a higher adsorption rate of the gold di-cyanide complex on activated carbon compared to gold-thiourea complexes.

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BACKGROUND: Basal energetic metabolism in sperm, particularly oxidative phosphorylation, is known to condition not only their oocyte fertilising ability, but also the subsequent embryo development. While the molecular pathways underlying these events still need to be elucidated, reactive oxygen species (ROS) could have a relevant role. We, therefore, aimed to describe the mechanisms through which mitochondrial activity can influence the first stages of embryo development. RESULTS: We first show that embryo development is tightly influenced by both intracellular ROS and mitochondrial activity. In addition, we depict that the inhibition of mitochondrial activity dramatically decreases intracellular ROS levels. Finally, we also demonstrate that the inhibition of mitochondrial respiration positively influences sperm DNA integrity, most likely because of the depletion of intracellular ROS formation. CONCLUSION: Collectively, the data presented in this work reveals that impairment of early embryo development may result from the accumulation of sperm DNA damage caused by mitochondrial-derived ROS.

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BACKGROUND: Basal energetic metabolism in sperm, particularly oxidative phosphorylation, is known to condition not only their oocyte fertilising ability, but also the subsequent embryo development. While the molecular pathways underlying these events still need to be elucidated, reactive oxygen species (ROS) could have a relevant role. We, therefore, aimed to describe the mechanisms through which mitochondrial activity can influence the first stages of embryo development. RESULTS: We first show that embryo development is tightly influenced by both intracellular ROS and mitochondrial activity. In addition, we depict that the inhibition of mitochondrial activity dramatically decreases intracellular ROS levels. Finally, we also demonstrate that the inhibition of mitochondrial respiration positively influences sperm DNA integrity, most likely because of the depletion of intracellular ROS formation. CONCLUSION: Collectively, the data presented in this work reveals that impairment of early embryo development may result from the accumulation of sperm DNA damage caused by mitochondrial-derived ROS.

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BACKGROUND: Cassava roots are widely consumed in tropical regions of Asia, Africa, and Latin America. Although the protein, vitamin, carotenoid, and mineral content in the leaves makes them a nutritionally attractive option, their consumption is limited due to their high levels of cyanogenic compounds (CCs). In this study, the CC content in different parts of the plant (leaves, storage root cortex, and parenchyma) was assessed at harvest for 50 landrace genotypes representative of cassava diversity in Latin America. The changes in CC in leaves at different physiological ages (3, 6, 9, and 11 months after planting) were also investigated. RESULTS: The average CC was higher in the cortex (804 ppm) and leaves (655 ppm) than in root parenchyma (305 ppm). Genotypes from different regions of Latin America, as identified by seven genetic diversity groups, differed significantly in CC levels. The Andean and Amazon groups had, respectively, the lowest (P = 0.0008) and highest (P < 0.0001) CC levels in all three parts of the plants. Cyanogenic compound concentrations were higher in leaves from young plants (P < 0.0001) and decreased with increasing physiological age. CONCLUSION: The results help to guide the selection of parental lines with low CC levels for breeding and to contribute to the expanded use of cassava and its by-products for food and feed. Cassava for fresh consumption, especially, requires varieties with low total CC content, especially in the root cortex and parenchyma. COL1108 (204, 213, and 174 ppm, respectively, in the parenchyma, cortex, and leaves) and PER297 (83, 238, and 299 ppm, respectively, in the parenchyma, cortex, and leaves) can fulfill this requirement. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

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Cyanide is a highly toxic substance present in wastewater from various industries. This study investigates the removal of cyanide species (CS) from aqueous solutions using the ZnTiO3/TiO2/H2O2/UVB system. ZnTiO3/TiO2 nanoparticles synthesized by the sol-gel method were characterized by powder X-ray diffractometry (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). The adsorption capacity of nanoparticles was tested by varying the pH of the solution, adsorbent concentration, and contact time. The adsorption of CS on ZnTiO3 and TiO2 surfaces was verified by Density Functional Theory (DFT) calculations. Photocatalytic experiments were achieved under UVB irradiation (λ = 310 nm). The response surface methodology (RSM) was used to optimize the CS removal efficiency. The detoxification effect was evaluated by acute toxicity tests with brine shrimp. The theoretical results show that the adsorption of CS is energetically more favorable on the ZnTiO3 surface than on the TiO2 surface. The experimental results show that the system consisting of ZnTiO3/TiO2 (200 mg L-1), H2O2 (0.1%), and UVB light removes 99% of CS from aqueous solutions after 60 min and reduces the mortality of nauplii in 90% after 90 min. This system was reused in five consecutive cycles with a total loss of efficiency of 30%.

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Inducing carotid body anoxia through the administration of cyanide can result in oxygen deprivation. The lack of oxygen activates cellular responses in specific regions of the central nervous system, including the Nucleus Tractus Solitarius, hypothalamus, hippocampus, and amygdala, which are regulated by afferent pathways from chemosensitive receptors. These receptors are modulated by the brain-derived neurotrophic factor receptor TrkB. Oxygen deprivation can cause neuroinflammation in the brain regions that are activated by the afferent pathways from the chemosensitive carotid body. To investigate how microglia, a type of immune cell in the brain, respond to an anoxic environment resulting from the administration of NaCN, we studied the effects of blocking the TrkB receptor on this cell-type response. Male Wistar rats were anesthetized, and a dose of NaCN was injected into their carotid sinus to induce anoxia. Prior to the anoxic stimulus, the rats were given an intracerebroventricular (icv) infusion of either K252a, a TrkB receptor inhibitor, BDNF, or an artificial cerebrospinal fluid (aCSF). After the anoxic stimulus, the rats were perfused with paraformaldehyde, and their brains were processed for microglia immunohistochemistry. The results indicated that the anoxic stimulation caused an increase in the number of reactive microglial cells in the hypothalamic arcuate, basolateral amygdala, and dentate gyrus of the hippocampus. However, the infusion of the K252a TrkB receptor inhibitor prevented microglial activation in these regions.

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El nitroprusiato de sodio fue aprobado desde 1974 como medicamento para las crisis hipertensivas. Desde entonces existe controversia sobre el potencial tóxico del mismo. La toxicidad por cianuro es una complicación poco común del nitroprusiato de sodio, que puede ser difícil de diagnosticar en pacientes críticamente enfermos. Dentro de los factores de riesgo está la utilización de infusiones prolongadas y dosis altas, por lo que se sugiere que la dosis no exceda 2 µg/kg/min. A continuación, se reporta el caso de un paciente de 49 años que ingresa a un servicio de urgencias después de un síndrome cerebrovascular y una emergencia hipertensiva que requirió infusión de nitroprusiato de sodio, seguida de signos y síntomas, los cuales sugirieron toxicidad. Entre dichos síntomas predominaban los cambios neurológicos, por lo cual fue manejado con hiposulfito de sodio y hubo una buena respuesta. El objetivo de este reporte de caso es sensibilizar al personal de salud sobre la necesidad de un uso adecuado del nitroprusiato y sobre la importancia de sospechar toxicidad en paciente con factores de riesgo.

Sodium Nitroprusside has been approved since 1974 as a medication for hypertensive crises. However, there has been ongoing controversy regarding its potential toxicity. Cyanide toxicity is a rare complication of Sodium Nitroprusside, which can be challenging to diagnose in critically ill patients. Risk factors include prolonged infusions and high doses; hence it is suggested that the dose should not exceed 2 µg/kg/min. Here, we present the case of a 49-year-old patient who entered the emergency department after a cerebrovascular event and a hypertensive emergency that required Sodium Nitroprusside infusion, followed by signs and symptoms suggestive of toxicity. Neurological changes were predominant among these symptoms, and the patient was managed with sodium thiosulfate, resulting in a good response. The objective of this case report is to raise awareness among healthcare professionals about the need for appropriate use of Sodium Nitroprusside and the importance of suspecting toxicity in patients with risk factors.

O nitroprussiato de sódio foi aprovado desde 1974 como medicamento para crises hipertensivas. Desde então tem havido controvérsia sobre o seu potencial tóxico. A toxicidade por cianeto é uma complicação rara do nitroprussiato de sódio, que pode ser difícil de diagnosticar em pacientes gravemente enfermos. Entre os fatores de risco está o uso de infusões prolongadas e altas doses, por isso sugere-se que a dose não ultrapasse 2 µg/kg/min. Relata-se a seguir o caso de uma paciente de 49 anos admitida em pronto-socorro após síndrome cerebrovascular e emergência hipertensiva com necessidade de infusão de nitroprussiato de sódio acompanhada de sinais e sintomas sugestivos de toxicidade. Dentre esses sintomas, predominaram as alterações neurológicas, para as quais foi tratado com hipossulfito de sódio e apresentou boa resposta. O objetivo deste relato de caso é sensibilizar os profissionais de saúde sobre a necessidade do uso adequado do nitroprussiato e sobre a importância de suspeitar de toxicidade em pacientes com fatores de risco.

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In this study, zeolites prepared by the hydrothermal method from Ecuadorian clay were combined with the precursor clay and with the semiconductor ZnTiO3/TiO2 prepared by the sol-gel method to adsorb and photodegrade cyanide species from aqueous solutions. These compounds were characterized by X-ray powder diffraction, X-ray fluorescence, scanning electron microscopy, energy-dispersive X-rays, point of zero charge, and specific surface area. The adsorption characteristics of the compounds were measured using batch adsorption experiments as a function of pH, initial concentration, temperature, and contact time. The Langmuir isotherm model and the pseudo-second-order model fit the adsorption process better. The equilibrium state in the reaction systems at pH = 7 was reached around 130 and 60 min in the adsorption and photodegradation experiments, respectively. The maximum cyanide adsorption value (73.37 mg g-1) was obtained with the ZC compound (zeolite + clay), and the maximum cyanide photodegradation capacity (90.7%) under UV light was obtained with the TC compound (ZnTiO3/TiO2 + clay). Finally, the reuse of the compounds in five consecutive treatment cycles was determined. The results reflect that the compounds synthesized and adapted to the extruded form could potentially be used for the removal of cyanide from wastewater.

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Artisanal and small-scale gold mining (ASGM) is the largest source of anthropogenic Hg emissions on the planet. In addition, Hg-contaminated tailings are often reprocessed with sodium cyanide (NaCN) to extract the residual gold remaining in the material. This leads to the formation of mercury cyanide (Hg(CN)2) complexes, which are often discharged in untreated form into local drainages, leading to large amounts of free cyanide being released. However, data on mercury-cyanide interactions are scarce. In this study, we investigated the impact of cyanide and Hg bioavailability in zebrafish when added as Hg(CN)2. Different concentrations of Hg(CN)2 and NaCN were used, leading to an LC50 of 0.53 mg.L-1 for NaCN and 0.16 mg.L-1 for Hg(CN)2. Analyzing free cyanide concentrations in aquarium water, >40% dissociation was observed for NaCN and about 5% for Hg(CN)2. The accumulation of total Hg (THg) in the brain, gills, muscle and kidney was quantified. All fish exposed to Hg(CN)2 had higher THg levels than their controls and kidney was the tissue with higher Hg(CN)2 accumulation. Histological effects on the kidney and gills of both cyanides in D. rerio tissues were investigated, suggesting renal alterations in fish exposed to Hg(CN)2 and showing hyperplasia in the gills of animals exposed to NaCN and Hg(CN)2. The results alert to the risks of the presence of these complexes in aquatic environments.

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