Search Results (11)

Chromium pollution has emerged as a critical environmental concern, prompting extensive research into the chemical and mineralogical properties of refined ferrochrome (RFC) slag, the leaching of chromium using sulfuric acid, and the adsorption of chromium cations onto natural zeolite. The aim of the study is to analyze the chemical and mineralogical properties of purified ferrochrome slag (RFC) from the Aktobe Ferroalloy Plant and its leaching with sulfuric acid, as well as to study the effectiveness of Shankanai zeolite in the adsorption of chromium cations from a sulfuric acid solution to improve waste management in the ferrochrome industry. Semi-quantitative X-ray analysis reveals that the dominant phase in RFC slag is olivine (50.7% Ca₂SiO₄). The optimal chromium transition rate (16.67%) occurs in dilute H₂SO₄ (23%) after 145 min of leaching, while the highest transition efficiency (18.0–18.5%) is achieved at 90 °C with a leaching duration of 145–180 min. Chromium in the RFC slag cake is predominantly in the divalent state, existing as pentahydrate chromium (II) sulfate (CrSO₄•5H₂O). The chromium sorption process was studied in a sulfuric acid solution obtained after leaching of ferrochrome slags. The process of chromium sorption by Shankanai zeolite from sulfuric acid has been studied for the first time, and the influence of the main technological parameters of the process on the degree of its purification has been established. It was determined that the highest degree of purification of a chromium-containing sulfuric acid solution is achieved with a ratio of zeolite:chromium-containing sulfuric acid solution equal to 1:10, heated to 35 °C for 15 min, and it reaches (63.6–69.0%). The natural zeolite of the Shankanai deposit is an effective, and inexpensive sorbent for cleaning aggressive media, particularly media contaminated with chromium-containing sulfuric acid. X-ray diffraction analysis further confirmed that both chromium and sulfur ions participate in the sorption process, as evidenced by microstructural changes in the zeolite, including pore filling and smoothing observed in microphotographs. These findings underscore the potential of natural zeolite as an efficient and cost-effective adsorbent for the remediation of chromium-contaminated solutions following sulfuric acid leaching. Its ability to adsorb chromium ions highlights its significant applicability in environmental cleanup efforts. This study contributes to sustainability by offering an environmentally friendly and cost-effective method for chromium removal, reducing industrial waste impact and promoting circular economy principles by utilizing natural zeolite, a readily available and recyclable adsorbent. Full article

Dextro-transposition of the great arteries (D-TGA) is a critical congenital heart defect that can impact neurodevelopment due to cerebral perfusion and oxygenation disorders followed by alterations in synaptogenesis, gyrification, sulcation, and the microstructure. Brain injuries can occur both pre-operatively and postoperatively, especially white matter injuries, neuronal loss, and stroke. Materials and Methods: In a retrospective study conducted at a tertiary center between 2016 and 2023, we investigated the early effects of Prostaglandin E1 (PGE1) administration and balloon atrial septostomy (BAS) on cerebral blood flow and oxygenation in inborn neonates with D-TGA. Cerebral Doppler Ultrasound in the anterior cerebral artery (ACA) was performed to assess the resistive index (RI), Peak Systolic Velocity (PSV), and End-Diastolic Velocity (EVD) before PGE1, before the BAS procedure, and 24 h after birth. Cerebral regional saturations of oxygen (crSO₂) and cerebral fractional tissue oxygen extraction (cFTOE) were evaluated. D-TGA patients were divided into the PGE1 group and the PGE1 + BAS group. Age-matched healthy controls were used for comparison. Results: All 83 D-TGA newborns received PGE1 within two hours after delivery, of whom 46 (55.42%) underwent BAS. In addition, 77 newborns composed the control group. PGE1 administration increased crSO₂ from 47% to 50% in the PGE1 group, but lower than in controls at 24 h of life, while cFTOE remained elevated. The RI increased 24 h after delivery (0.718 vs. 0.769; p = 0.000002) due to decreased EDV (10.71 vs. 8.74; p < 0.0001) following PGE1 treatment. The BAS procedure resulted in a significant increase in crSO₂ from 42% to 51% at 24 h of life in the PGE1 + BAS group. Doppler parameters exhibited a similar trend as observed in the PGE1 group. Conclusions: PGE1 treatment and BAS are lifesaving interventions that may improve cerebral perfusion and oxygenation in newborns with D-TGA during the transition period, as reflected by increasing SpO₂ and crSO₂. Full article

The conventional synthesis of the Metal–Organic Framework (MOF) MIL-101(Cr)-SO₃H employs hydrofluoric acid as the modulator, posing handling challenges due to its irritating, corrosive, and toxic nature, as well as its reactivity with glass and metals. This study aims to find a new hydrofluoric acid-free synthesis route for MIL-101(Cr)-SO₃H, proposing acetic acid and nitric acid as modulator alternatives. Four MIL-101(Cr)-SO₃H samples were prepared: one without any modulator and the other three using a similar volume of either hydrofluoric acid, acetic acid, or nitric acid as the modulator. The so-obtained mass yield ranked as follows: without any modulator (32.6%) > acetic acid (29.6%) > nitric acid (25.2%) >> hydrofluoric acid (2.2%), whereas the total pore volume and BET surface area followed the order: hydrofluoric acid (0.87 cm³ g⁻¹, 1862 m² g⁻¹) > nitric acid (0.81 cm³ g⁻¹, 1554 m² g⁻¹) > acetic acid (0.72 cm³ g⁻¹, 1374 m² g⁻¹) > without any modulator (0.69 cm³ g⁻¹, 1342 m² g⁻¹). Despite the superior texture parameters obtained using hydrofluoric acid, the low synthesis yield and associated risks make this route non-viable. Acetic or nitric acid-based synthesis offers a promising alternative with a drastically higher yield, safer handling, and reduced environmental impact. In an attempt to improve the textural properties of the hydrofluoric acid-free MOFs, a series of samples were produced with increasing amounts of acetic acid, achieving BET surface areas of up to 1504 m² g⁻¹ and pore volumes of up to 0.81 cm³ g⁻¹. Full article

Background: During a newborn’s adaptation to extrauterine life, many changes take place that are influenced by various factors. The type of delivery and anaesthesia strategy utilised during labour can modify these adaptive modifications. In this regard, this study was designed to compare the effects of general and spinal anaesthesia on cerebral and renal oxygenation after elective caesarean deliveries. Methods: This randomised controlled study comprised sixty parturient women who were over 18 years old and had a gestational age between 37 and 41 weeks. All participants had an ASA (American Society of Anesthesiologists) classification of II. Neonatal cerebral (CrSO₂) and renal (RrSO₂) regional oxygen saturations were assessed using near-infrared spectroscopy. Additionally, the 1st–5th min Apgar scores, preductal and postductal peripheral oxygen saturation (SpO₂), and perfusion index were recorded in both the general anaesthesia and spinal anaesthesia groups. Results: There was no statistically significant difference between the two groups in terms of CrSO₂ or RrSO₂ values. The values of CrSO₂ and RrSO₂ in both groups showed a significant rise from the 10th to the 15th min, respectively. Conclusions: General and spinal anaesthesia techniques used for cesarean delivery have similar effects on neonatal cerebral and renal oxygenation. Full article

The potential benefits of microwave irradiation for fructose dehydration into 5 hydroxymethylfurfural (5-HMF) have been quantified over a sulfonated metal–organic framework (MOF), MIL 101(Cr)-SO₃H. The effects of temperature (140–170 °C), batch time (5–300 min), and catalyst-to-substrate ratio (0.1–0.01 g/g) were systematically mapped. After 10 min of microwave (MW) irradiation at 140 °C in a DMSO–acetone reaction medium, practically complete fructose conversion was obtained with a 70% yield of 5-HMF. Without MW, i.e., using conventional heating (CH) at the same conditions, the fructose conversion was limited to 13% without any 5-HMF yield. Rather, 90 min of CH was required to reach a similarly high conversion and yield. The profound impact of moving from CH towards MW conditions on the reaction kinetics, also denoted as the microwave effect, has been quantified through kinetic modeling via a change in the Gibbs free energy of the transition state. The modeling results revealed an eight-fold rate coefficient enhancement for fructose dehydration owing to MW irradiation, while the temperature dependence of the various reaction steps almost completely disappeared in the investigated range of operating conditions. Full article

Purpose: To determine the effects of non-ictal electroencephalogram (EEG) changes on cerebrovascular autoregulation (AR) using the cerebral oximetry index (COx). Materials and Methods: Mean arterial blood pressure (MAP), cerebral tissue oxygenation (CrSO2), and EEG were acquired for 96 h. From all of the EEG recordings, 30 min recording segments were extracted using the endotracheal suction events as the guide. EEG recordings were classified as EEG normal and EEG abnormal groups. Each 30 min segment was further divided into six 5 min epochs. Continuous recordings of MAP and CrSO2 by near-infrared spectroscopy (NIRS) were extracted. The COx value was defined as the concordance (R) value of the Pearson correlation between MAP and CrSO2 in a 5 min epoch. Then, an Independent-Samples Mann-Whitney U test was used to analyze the number of epochs within the 30 min segments above various R cutoff values (0.2, 0.3, and 0.4) in normal and abnormal EEG groups. A p-value < 0.05 was considered significant, and all analyses were two-tailed. Results: Among 16 sedated, mechanically ventilated children, 382 EEG recordings of 30 min segments were analyzed. The proportions of epochs in each 30 min segment above the R cutoff values were similar between the EEG normal and EEG abnormal groups (p > 0.05). The median concordance values for CSrO₂ and MAP in EEG normal and EEG abnormal groups were similar (0.26 (0.17–0.35) and 0.18 (0.12–0.31); p = 0.09). Conclusions: Abnormal EEG patterns without ictal changes do not affect cerebrovascular autoregulation in sedated and mechanically ventilated children. Full article

Body temperature (BT) management remains a challenge in neonatal intensive care, especially during resuscitation after birth. Our aim is to analyze whether there is an association between the BT and cerebral and peripheral tissue oxygen saturation (crSO₂/cTOI and prSO₂), arterial oxygen saturation (SpO₂), and heart rate (HR). The secondary outcome parameters of five prospective observational studies are analyzed. We include preterm and term neonates born by Caesarean section who received continuous pulse oximetry and near-infrared spectroscopy monitoring during the first 15 min, and a rectal BT measurement once in minute 15 after birth. Four-hundred seventeen term and 169 preterm neonates are included. The BT did not correlate with crSO₂/cTOI and SpO₂. The BT correlated with the HR in all neonates (ρ = 0.210, p < 0.001) and with prSO₂ only in preterm neonates (ρ = −0.285, p = 0.020). The BT was lower in preterm compared to term infants (36.7 [36.4–37.0] vs. 36.8 [36.6–37.0], p = 0.001) and prevalence of hypothermia was higher in preterm neonates (29.5% vs. 12.0%, p < 0.001). To conclude, the BT did not correlate with SpO₂ and crSO₂/cTOI, however, there was a weak positive correlation between the BT and the HR in the whole cohort and a weak correlation between the BT and prSO₂ only in preterm infants. Preterm neonates had a statistically lower BT and suffered significantly more often from hypothermia during postnatal transition. Full article

Tanneries produce significant quantities of hazardous waste/waters and, according to international environmental organizations, their further recycling/reuse/exploitation in the context of circular economy is considered mandatory. A relevant case study is the recovery of Cr(III), used in large amounts during the tanning process, which can be recovered from the corresponding industrial waste/sludge. The aim of this work is to optimize the Cr(III) hydrometallurgical recovery from the tannery sludge by examining the major experimental conditions that affect the efficiency of its different sequential steps, namely extraction/leaching and precipitation. The chemical characterization revealed that tannery sludge contains high amounts of Cr(III) (14.1%), Ca (14.8%), and organic matter (22%). The extraction of Cr(III) was examined by applying various common acids (H₂SO₄, HNO₃, HCl) in the concentration range of 0.02–2 N. The highest selectivity and efficiency (93%) were obtained by the addition of H₂SO₄ as the insoluble CaSO₄ and soluble CrSO₄⁺ species were formed. Regarding the experimental conditions, only the increase in temperature showed a positive effect on Cr recovery. The Cr(III) can be further precipitated from the resulting leaching solution by increasing the equilibrium pH; the precipitate with the higher purity in Cr(OH)₃ (70%) was obtained by the application of NaOH and could possibly be reused by tanneries. Full article

The effluent of tanneries is a hazardous waste and a combination of physical-chemical and biological techniques is required for its treatment. As a result of the previous processes, a sludge with high chromium content is produced. So, the aim of this study is the hydrometallurgical recovery of chromium in the context of a circular economy. According to chemical characterization, the only form of metal that existed in the sludge was the trivalent, while its content was up to 14.8% w/w. Among the examined acids, the highest efficiency in Cr(III) leaching was achieved by the H₂SO₄ (93%), due to the formation of the soluble CrSO₄⁺. Regarding the step of precipitation, no significant varions were observed between the two alkaline medias that were tested, namely NaOH and Ca(OH)₂. Full article

Background: To evaluate the effectiveness/side-effects of osteopathic manipulation treatment (OMT) performed on the 7th post-natal day, on cerebro–splanchnic oximetry, tissue activation and hemodynamic redistribution in late preterm (LP) infants by using near infrared spectroscopy (NIRS). Methods: Observational pretest-test study consisting in a cohort of 18 LPs who received OMT on the 7th post-natal day. NIRS monitoring was performed at three different time-points: 30 min before (T0), (30 min during (T1) and 30 min after OMT (T2). We evaluated the effects of OMT on the following NIRS parameters: cerebral (c), splanchnic (s) regional oximetry (rSO2), cerebro–splanchnic fractional tissue oxygen extraction (FTOE) and hemodynamic redistribution (CSOR). Results: crSO2 and cFTOE significantly (P < 0.001) improved at T0-T2; srSO2 significantly (P < 0.001) decreased and sFTOE increased at T0-T1. Furthermore, srSO2 and sFTOE significantly improved at T1-T2. Finally, CSOR significantly (P < 0.05) increased at T0-T2. Conclusions: The present data show that OMT enhances cerebro–splanchnic oximetry, tissue activation and hemodynamic redistribution in the absence of any adverse clinical or laboratory pattern. The results indicate the usefulness of further randomized studies in wider populations comparing the effectiveness of OMT with standard rehabilitation programs. Full article

Crude rubber seed oil (CRSO) is a promising but currently underutilized biodiesel feedstock alternative, extracted by pressing the seeds of the rubber tree (Hevea brasiliensis). Rubber trees are cultivated across more than 11.4 million hectares worldwide, mainly in Southeast Asia. Despite their suitability as a biodiesel feedstock source, rubber seeds are currently treated as waste in the monocultural plantation system. To date, no assessments have been performed to examine the potential impact of rubber seed-based biodiesel production on GHG emissions. This study analyses the global warming potential of rubber seed methyl ester (RSME) production in Southeast Asia. The functional unit used is 1 MJ of biodiesel. A sensitivity analysis assesses the influence of key parameters (e.g., rubber seed yield) on the GHG mitigation potential. A scenario analysis evaluates the effect of using RSME by-products for energy generation. In comparison to fossil diesel, RSME has a carbon mitigation potential of 67 g CO₂.eq. MJ⁻¹, based on allocation by mass. On the condition of compliance with international sustainability standards that call for deforestation-free value chains, the generation of RSME biodiesel on rubber tree plantations in Southeast Asia would have a total mitigation potential of around 2.8 million tonnes of CO₂ eq. per year. Full article