Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 109
Filtrar
1.
BMC Endocr Disord ; 24(1): 58, 2024 Apr 30.
Artículo en Inglés | MEDLINE | ID: mdl-38689308

RESUMEN

OBJECTIVE: The objective of this study was to evaluate the association between hyperthyroidism and the risk of developing erectile dysfunction (ED). METHODS: A comprehensive search of multiple databases, including PubMed, Embase, Cochrane, and Web of Science, was conducted to identify relevant studies investigating the relationship between hyperthyroidism and ED in men. The quality of the included studies was assessed using the Newcastle‒Ottawa Quality Rating Scale, and a meta-analysis was performed using Stata 16.0 and RevMan 5.3 software. RESULTS: A total of four papers encompassing 25,519 study subjects were included in the analysis. Among these, 6,429 individuals had hyperthyroidism, while 19,090 served as controls. The overall prevalence of ED in patients with hyperthyroidism was determined to be 31.1% (95% CI 0.06-0.56). In patients with uncomplicated hyperthyroidism, the incidence of ED was 21.9% (95% CI 0.05-0.38). The combined odds ratio (OR) for the four studies was 1.73 (OR: 1.73; 95% CI [1.46-2.04]; p < .00001). CONCLUSION: Our findings demonstrate a higher incidence of ED in patients with hyperthyroidism. These results provide valuable information for healthcare professionals and can facilitate discussions surrounding appropriate treatment options for ED in patients with hyperthyroidism.


Asunto(s)
Disfunción Eréctil , Hipertiroidismo , Humanos , Hipertiroidismo/epidemiología , Hipertiroidismo/complicaciones , Disfunción Eréctil/epidemiología , Disfunción Eréctil/etiología , Masculino , Prevalencia
2.
J Hazard Mater ; 471: 134413, 2024 Jun 05.
Artículo en Inglés | MEDLINE | ID: mdl-38669935

RESUMEN

Heavy metal pollution at an abandoned smelter pose a significant risk to environmental health. However, remediation strategies are constrained by inadequate knowledge of the polymetallic distribution, speciation patterns, and transformation factors at these sites. This study investigates the influence of soil minerals, heavy metal occurrence forms, and environmental factors on heavy metal migration behaviors and speciation transformations. X-ray diffraction analysis revealed that the minerals associated with heavy metals are mainly hematite, franklinite, sphalerite, and galena. Sequential extraction results suggest that lead and zinc are primarily present in the organic-sulfide fractions (F4) and residual form (F5) in the soil, accounting for over 70% of the total heavy metal content. Zinc displayed greater instability in carbonate-bound (16%) and exchangeable (2%) forms. The migration and diffusion patterns of heavy metals in the subsurface environment were visualized through the simulation of labile state heavy metals, demonstrating high congruence with groundwater pollution distribution patterns. The key environmental factors influencing heavy metal stable states (F4 and F5) were assessed by integrating random forest models and redundancy analysis. Primary factors facilitating Pb transformation into stable states were available phosphorus, clay content, depth, and soil organic matter. For Zn, the principal drivers were Mn oxides, soil organic matter, clay content, and inorganic sulfur ions. These findings enhance understanding of the distribution and transformation of heavy metal speciation and can provide valuable insights into controlling heavy metal pollution at non-ferrous smelting sites.

3.
J Gastroenterol Hepatol ; 39(4): 658-666, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38251791

RESUMEN

BACKGROUND AND AIM: Fexuprazan is a novel potassium-competitive acid blocker (P-CAB). This study aimed to explore the noninferior efficacy and safety of fexuprazan to esomeprazole in treating erosive esophagitis (EE). METHODS: This was a phase III, randomized, double-blind multicenter study. Patients with endoscopically confirmed EE were randomized to receive fexuprazan 40 mg or esomeprazole 40 mg once a daily for 4-8 weeks. The healing rates of EE, symptom response, GERD-health-related quality life (GERD-HRQL), and treatment-emergent adverse events (TEAEs) were compared between fexuprazan group and esomeprazole group. RESULTS: A total of 332 subjects were included in full analysis set (FAS) and 311 in per-protocol set (PPS). The healing rates of fexuprazan and esomeprazole groups at 8 weeks were 88.5% (146/165) and 89.0% (145/163), respectively, in FAS and 97.3% (145/149) and 97.9% (143/146), respectively, in PPS. Noninferiority of fexuprazan compared with esomeprazole according to EE healing rates at 8 weeks was demonstrated in both FAS and PPS analysis. No significant difference was found between groups in EE healing rates at 4 weeks, symptom responses, and changes of GERD-HRQL. The incidence of drug-related AEs was 19.4% (32/165) in fexuprazan arm and 19.6% (32/163) in esomeprazole arm. CONCLUSION: This study demonstrated noninferior efficacy of fexuprazan to esomeprazole in treating EE. The incidence of TEAEs was similar between fexuprazan and esomeprazole. Trial registration number NCT05813561.


Asunto(s)
Aminas , Esofagitis Péptica , Reflujo Gastroesofágico , Úlcera Péptica , Pirroles , Humanos , Esomeprazol/efectos adversos , Esofagitis Péptica/tratamiento farmacológico , Esofagitis Péptica/etiología , Resultado del Tratamiento , Reflujo Gastroesofágico/tratamiento farmacológico , Reflujo Gastroesofágico/complicaciones , Úlcera Péptica/complicaciones , Método Doble Ciego , Inhibidores de la Bomba de Protones/efectos adversos
4.
ACS Pharmacol Transl Sci ; 6(10): 1508-1517, 2023 Oct 13.
Artículo en Inglés | MEDLINE | ID: mdl-37854615

RESUMEN

Cisplatin (DDP) is a first-line chemotherapeutic drug against lung cancer. Nonetheless, the effectiveness of this drug is hampered by drug resistance. Overcoming drug resistance is crucial for improving the outcomes of lung cancer treatment. Here, we reported the effect of CX-23, an activated triptolide analogue that targets NAD (P)H quinone dehydrogenase 1 (NQO1), on DDP-resistant lung cancer and sensitizes DDP-resistant lung cancer to chemotherapy. Our findings unveiled the antiproliferative activity of CX-23 against both A549- and DDP-resistant A549 (A549/DDP) cells while enhancing the chemosensitivity of these cells to DDP. Notably, CX-23 demonstrated no toxicity toward normal lung cells. Further investigations revealed that CX-23 exerts its effects by blocking AKT phosphorylation, leading to reduced expression of Mcl-1 and Bcl-2, and upregulating cleaved-caspase-3 levels, ultimately inducing apoptosis in cancer cells. CX-23 can be rapidly transformed in both A549 and A549/DDP cell lysates while remaining stable in mouse plasma and normal lung tissues. Pharmacokinetic analysis showed that CX-23 can distribute to lung tissues. Moreover, in vivo studies showed that CX-23 can prevent DDP-resistant lung cancer progression without causing any toxicity in the liver, kidneys, or lungs after 6 weeks of treatment. The combination of CX-23 and DDP not only significantly inhibited tumor progression compared to DDP alone but also attenuated DDP-induced kidney toxicity. These findings suggest that CX-23 alone or in combination with DDP may provide an alternative therapeutic option for DDP-resistant lung cancer.

5.
Front Pharmacol ; 14: 1218201, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37274112
6.
Comput Biol Med ; 159: 106858, 2023 06.
Artículo en Inglés | MEDLINE | ID: mdl-37087778

RESUMEN

Foot ulcers are a common complication of diabetes mellitus, which is associated with high morbidity and mortality among diabetic patients. The present study aims to investigate novel wound healing pathways in diabetic foot ulcers (DFU) through proteomics and a network pharmacology analysis. Tandem mass tag (TMT) labeled quantitative proteomics method was performed to evaluate the protein expression profile in wound tissues from healthy controls (HC) and DFU. Kyoto Encyclopedia of Genes (KEGG) and Genomes enrichment analysis (GO) was conducted based on differentially expressed proteins (DEPs) to discover the potential pathways associated with DFU. Western blot analysis was used to confirm the probable DFU-related targets. Proteomics analysis discovered 509 DEPs (248 upregulated and 261 downregulated proteins). Go and KEGG further evaluated the DEPs to discover the DFU-related pathways. According to network pharmacology study, three main targets (metalloproteinase 9 (MMP9), Fatty acid-binding protein 5 (FABP5), and integrin subunit alpha M (ITGAM)) play crucial roles in signaling pathways. Staphylococcus aureus infection and leukocyte transendothelial migration pathways significantly enriched in DFU. In addition, it was confirmed that three critical targets were elevated in diabetes mouse wound tissues. The study confirmed the presence of protein alterations in the wound-healing process of DFU mice and may provide fresh insights into the molecular mechanisms driving DFU.


Asunto(s)
Diabetes Mellitus , Pie Diabético , Ratones , Animales , Pie Diabético/genética , Proteómica , Cicatrización de Heridas
7.
World J Clin Cases ; 11(9): 2029-2035, 2023 Mar 26.
Artículo en Inglés | MEDLINE | ID: mdl-36998943

RESUMEN

BACKGROUND: The standard treatment for advanced T2 gastric cancer (GC) is laparoscopic or surgical gastrectomy (either partial or total) and D2 lymphadenectomy. A novel combined endoscopic and laparoscopic surgery (NCELS) has recently been proposed as a better option for T2 GC. Here we describe two case studies demonstrating the efficacy and safety of NCELS. CASE SUMMARY: Two T2 GC cases were both resected by endoscopic submucosal dissection and full-thickness resection and laparoscopic lymph nodes dissection. This method has the advantage of being more precise and minimally invasive compared to current methods. The treatment of these 2 patients was safe and effective with no complications. These cases were followed up for nearly 4 years without recurrence or metastasis. CONCLUSION: This novel method provides a minimally invasive treatment option for T2 GC, and its potential indications, effectiveness and safety needs to be further evaluated in controlled studies.

8.
J Environ Manage ; 337: 117749, 2023 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-36940603

RESUMEN

Opal (SiO2·nH2O, amorphous silica), the by-product of alumina extraction from coal fly ash (CFA), has a strong adsorption capacity and is also an important component of clay minerals in soils. The combining of opal with sand to form artificial soils is an effective disposal strategy for large-scale CFA stockpiles and reduction of environmental risk. Nevertheless, its poor physical condition limits plant growth. Organic matter (OM) amendments have broad potential applications for water-holding and improving soil aggregation. Effects of OMs (vermicompost (VC), bagasse (BA), biochar (BC) and humic acid (HA)) on the formation, stability and pore characteristics of opal/sand aggregates were evaluated through 60-day laboratory incubation experiments. Results demonstrated that four OMs could reduce pH, with BC having the most significant effect, VC significantly increasing the electrical conductivity (EC) and TOC content of the aggregates. Except for HA, other OMs could improve the aggregates' water-holding capacity. The mean weight diameter (MWD) and percentage of >0.25 mm aggregates (R0.25) of BA-treated aggregates were the largest, and BA had the most noticeable contribution to macro-aggregate's formation. The best aggregate stability was obtained with HA treatment, meanwhile the percentage of aggregate destruction (PAD0.25) decreased with the addition of HA. After amendments, the proportion of organic functional groups increased, which favored aggregate's formation and stability; the surface pore characteristics were improved, with the porosity ranging from 70% to 75%, reaching the level of well-structured soil. Overall, the addition of VC and HA can effectively promote aggregates' formation and stabilization. This research may play a key role in converting CFA or opal into artificial soil. The combining of opal with sand to form artificial soil will not only solve the environmental problems caused by large-scale CFA stockpiles but will also enable the comprehensive utilization of siliceous materials in agriculture.


Asunto(s)
Arena , Dióxido de Silicio , Suelo/química , Agua
9.
Front Plant Sci ; 13: 1071458, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36544877

RESUMEN

Camellia petelotii (Merr.) Sealy and Camellia impressinervis Chang & Liang belong to the golden subgroup of Camellia (Theaceae). This subgroup contains the yellow-flowering species of the genus, which have high medicinal and ornamental value and a narrow geographical distribution. These species differ in their tolerance to high light intensity. This study aimed to explore the differences in their light-stress responses and light damage repair processes, and the effect of these networks on secondary metabolite synthesis. Two-year-old plants of both species grown at 300 µmol·m-2·s-1 photosynthetically active radiation (PAR) were shifted to 700 µmol·m-2·s-1 PAR for 5 days shifting back to 300 µmol·m-2·s-1 PAR for recovery for 5 days. Leaf samples were collected at the start of the experiment and 2 days after each shift. Data analysis included measuring photosynthetic indicators, differential transcriptome expression, and quantifying plant hormones, pigments, and flavonoids. Camellia impressinervis showed a weak ability to recover from photodamage that occurred at 700 µmol·m-2·s-1 compared with C. petelotii. Photodamage led to decreased photosynthesis, as shown by repressed transcript abundance for photosystem II genes psbA, B, C, O, and Q, photosystem I genes psaB, D, E, H, and N, electron transfer genes petE and F, and ATP synthesis genes ATPF1A and ATPF1B. High-light stress caused more severe damage to C. impressinervis, which showed a stronger response to reactive oxygen species than C. petelotii. In addition, high-light stress promoted the growth and development of high zeatin signalling and increased transcript abundance of adenylate dimethylallyl transferase (IPT) and histidine-containing phosphotransferase (AHP). The identification of transcriptional differences in the regulatory networks that respond to high-light stress and activate recovery of light damage in these two rare species adds to the resources available to conserve them and improve their value through molecular breeding.

10.
ACS Pharmacol Transl Sci ; 5(9): 819-828, 2022 Sep 09.
Artículo en Inglés | MEDLINE | ID: mdl-36110377

RESUMEN

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and fatal lung disease. Rho-associated protein kinases (ROCK) 1/2 are promising therapeutic targets for the treatment of IPF. However, a single inhibition of each of them is insufficient to prevent bleomycin-induced lung fibrosis. The current work reported that bleomycin-induced lung fibrosis can be reduced by dual inhibition of ROCK1/2 with compound 1. We evaluated the dual-selective ROCK1/2 inhibition activity of compound 1, its toxicity, and its preliminary efficacy on bleomycin-induced lung fibrosis. In vitro, compound 1 served as the ROCK1/2 inhibitor with half-maximal inhibitory concentration (IC50) values of 165 ±10.4 nM for ROCK1 and 16.1 ± 2.82 nM for ROCK2. In NIH/3T3 cells, compound 1 inhibited the mRNA expression of COL 1A1 and α-SMA. At therapeutic levels, compound 1 exhibited neither hepatic nor cardiac toxicity, also no CYP450 enzyme inhibition. In vivo, compound 1 had good pharmacokinetic properties, and its oral administration reduced bleomycin-induced pulmonary fibrosis in rats. All the outcomes prove the drug-like characteristics of compound 1 for the treatment of IPF.

11.
ACS Pharmacol Transl Sci ; 5(8): 555-561, 2022 Aug 12.
Artículo en Inglés | MEDLINE | ID: mdl-35983271

RESUMEN

There exists a paucity of information on the pathogenesis of pterygium, a benign ocular tumor that scars the cornea and can lead to vision loss. The main recourse for pterygium is surgery; however, recurrence is observed. Matrix metalloproteinases (MMPs) are involved in the pathology of pterygium. The determination of the specific MMP involved among the 24 human enzymes has not been established due to challenges in MMP profiling. We used an affinity resin that binds specifically to the active forms of MMPs in the complex mixture of the cellular proteome. The proteomics analysis identified active MMP-14 and three related metalloproteinases, ADAM9, ADAM10, and ADAM17, in human pterygia. Inhibition of MMP-14 with the small-molecule inhibitor (R)-ND-336 was assessed in cell migration and collagen contraction assays. (R)-ND-336 attenuated human conjunctiva fibroblast migration and mitigated collagen contraction, both activities required for the formation of pterygium. (R)-ND-336 holds the promise of a therapeutic recourse for pterygium as an orphan disease.

12.
ACS Pharmacol Transl Sci ; 5(8): 548-554, 2022 Aug 12.
Artículo en Inglés | MEDLINE | ID: mdl-35983283

RESUMEN

Idiopathic pulmonary fibrosis (IPF), a fatal disease characterized by excessive matrix degradation and fibrosis, destroys the lung architecture and results in the inability of the lungs to absorb oxygen. The cause(s) of IPF is unknown and current treatments are palliative. Matrix metalloproteinases (MMPs) and A Disintegrin And Metalloproteinases (ADAMs) likely play roles in IPF progression. However, specific MMPs and ADAMs in IPF have not been identified due to challenges in MMP/ADAM profiling. We employed a designer affinity resin that binds exclusively to the active forms of MMPs and ADAMs and found by mass spectrometry higher levels of active MMP-1, ADAM9, ADAM10, and ADAM17 in lung tissues of IPF patients. Inhibition of MMP-1 and ADAM10 with the small-molecule inhibitor GI254023X in an in vitro lung fibrosis assay decreased the profibrotic protein α-smooth muscle actin (α-SMA). Our results indicate that inhibition of MMP-1 and ADAM10 may hold promise in treatment of IPF.

13.
ACS Chem Biol ; 17(6): 1357-1363, 2022 06 17.
Artículo en Inglés | MEDLINE | ID: mdl-35670779

RESUMEN

Pressure ulcers (PUs) are chronic wounds that lead to amputations and death. Little is known about why PUs are recalcitrant to healing. Wound healing is mediated by matrix metalloproteinases (MMPs). The 24 MMPs in humans each exist in three forms, of which only one is catalytically competent. We analyzed human PU samples using an affinity resin that exclusively binds to the catalytically competent MMPs. We identified by mass spectrometry the active forms of MMP-1, MMP-8, MMP-9, and MMP-14. Concentrations of MMP-8, MMP-9, and MMP-14 were higher in human PUs compared to the healthy tissue, whereas those for MMP-1 did not change. Decreasing levels of active MMP-9 as the PU improved argued for a detrimental role for this enzyme. In a mouse model of PUs, a highly selective inhibitor for MMP-9 and MMP-14, (R)-ND-336, accelerated wound closure in parallel with significant amelioration of ulcer stage. (R)-ND-336 holds promise as a first-in-class treatment for PUs.


Asunto(s)
Úlcera por Presión , Animales , Metaloproteinasa 1 de la Matriz , Metaloproteinasa 14 de la Matriz , Metaloproteinasa 8 de la Matriz/metabolismo , Metaloproteinasa 9 de la Matriz/metabolismo , Metilaminas , Ratones , Úlcera por Presión/tratamiento farmacológico , Proteómica , Sulfuros , Supuración
14.
J Biol Chem ; 298(7): 102095, 2022 07.
Artículo en Inglés | MEDLINE | ID: mdl-35660018

RESUMEN

Ascl2 has been shown to be involved in tumorigenesis in colorectal cancer (CRC), although its epigenetic regulatory mechanism is largely unknown. Here, we found that methylation of the Ascl2 promoter (bp -1670 ∼ -1139) was significantly increased compared to the other regions of the Ascl2 locus in CRC cells and was associated with elevated Ascl2 mRNA expression. Furthermore, we found that promoter methylation was predictive of CRC patient survival after analyzing DNA methylation data, RNA-Seq data, and clinical data of 410 CRC patient samples from the MethHC database, the MEXPRESS database, and the Cbioportal website. Using the established TET methylcytosine dioxygenase 2 (TET2) knockdown and ectopic TET2 catalytic domain-expression cell models, we performed glucosylated hydroxymethyl-sensitive quatitative PCR (qPCR), real-time PCR, and Western blot assays to further confirm that hypermethylation of the Ascl2 promoter, and elevated Ascl2 expression in CRC cells was partly due to the decreased expression of TET2. Furthermore, BCLAF1 was identified as a TET2 interactor in CRC cells by LC-MS/MS, coimmunoprecipitation, immunofluorescence colocalization, and proximity ligation assays. Subsequently, we found the TET2-BCLAF1 complex bound to multiple elements around CCGG sites at the Ascl2 promoter and further restrained its hypermethylation by inducing its hydroxymethylation using chromatin immunoprecipitation-qPCR and glucosylated hydroxymethyl-qPCR assays. Finally, we demonstrate that TET2-modulated Ascl2-targeted stem gene expression in CRC cells was independent of Wnt signaling. Taken together, our data suggest an additional option for inhibiting Ascl2 expression in CRC cells through TET2-BCLAF1-mediated promoter methylation, Ascl2-dependent self-renewal of CRC progenitor cells, and TET2-BCLAF1-related CRC progression.


Asunto(s)
Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico , Neoplasias Colorrectales , Metilación de ADN , Dioxigenasas , Proteínas Represoras , Proteínas Supresoras de Tumor , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/genética , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Línea Celular Tumoral , Cromatografía Liquida , Neoplasias Colorrectales/genética , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Dioxigenasas/genética , Dioxigenasas/metabolismo , Regulación Neoplásica de la Expresión Génica , Humanos , Regiones Promotoras Genéticas , Proteínas Represoras/genética , Proteínas Represoras/metabolismo , Espectrometría de Masas en Tándem , Proteínas Supresoras de Tumor/genética , Proteínas Supresoras de Tumor/metabolismo
15.
Pathogens ; 11(4)2022 Apr 07.
Artículo en Inglés | MEDLINE | ID: mdl-35456121

RESUMEN

Sclerotinia sclerotiorum is a notorious soilborne fungal pathogen that causes serious economic losses globally. The necrosis and ethylene-inducible peptide 1 (NEP1)-like proteins (NLPs) were previously shown to play an important role in pathogenicity in fungal and oomycete pathogens. Here, we generated S. sclerotiorum necrosis and ethylene-inducible peptide 2 (SsNEP2) deletion mutant through homologous recombination and found that SsNEP2 contributes to the virulence of S. sclerotiorum without affecting the development of mycelia, the formation of appressoria, or the secretion of oxalic acid. Although knocking out SsNEP2 did not affect fungal sensitivity to oxidative stress, it did lead to decreased accumulation of reactive oxygen species (ROS) in S. sclerotiorum. Furthermore, Ssnlp24SsNEP2 peptide derived from SsNEP2 triggered host mitogen-activated protein kinase (MAPK) activation, increased defense marker gene expression, and enhanced resistance to Hyaloperonospora arabidopsidis Noco2. Taken together, our data suggest that SsNEP2 is involved in fungal virulence by affecting ROS levels in S. sclerotiorum. It can serve as a pathogen-associated molecular pattern (PAMP) and trigger host pattern triggered immunity to promote the necrotrophic lifestyle of S. sclerotiorum.

16.
RSC Adv ; 12(7): 4162-4174, 2022 Jan 28.
Artículo en Inglés | MEDLINE | ID: mdl-35425423

RESUMEN

The conversion of Al-substituted goethite (Al-goethite) to hematite in gibbsitic bauxite is conducive to alumina extraction during the Bayer process and the enrichment of iron minerals in red mud. In this work, mineralogical characteristics of gibbsitic bauxite were identified by AMICS analysis, and the low-temperature thermal conversion behavior of both synthetic Al-goethite and natural Al-goethite in gibbsitic bauxite were investigated through thermal gravity analysis, phase transformation, and microstructure studies. Results show that the proportion of aluminum in Al-goethite reached 12.68% of the total aluminum content in gibbsitic bauxite. The conversion of synthetic Al-goethite to hematite starts at ∼280 °C, while that of natural Al-goethite starts at ∼320 °C, and the addition of NaOH can accelerate the conversion. The formed hematite inherits the needle-like appearance of the original Al-goethite, has many holes on the surface due to dehydroxylation, and no migration of aluminum elements occurs during the roasting process, indicating that Al-goethite transformed into porous Al-substituted hematite (Al-hematite), which is beneficial to the extraction of the aluminum retained in the hematite structure during Bayer digestion. To confirm the above results, digestion experiments (without or with roasting for typical Bayer digestion or low-temperature roasting-Bayer digestion) were carried out with gibbsitic bauxite and the one roasted at 400 °C for 30 min as raw materials, respectively. Compared to the typical Bayer digestion, the relative alumina recovery of low-temperature roasting-Bayer digestion increased from 90.06% to 95.65%, the red mud yield decreased from 36.32% to 34.08%, and the grade of Fe in red mud increased from 48.45% to 52.88% at 270 °C for 60 min. Enhanced transformation of Al-goethite significantly improves alumina recovery and the resultant iron-rich red mud can be easily co-processed in the steel industry, thus significant emission reduction of red mud from the Bayer system might be achieved.

17.
RSC Adv ; 12(8): 4562-4571, 2022 Feb 03.
Artículo en Inglés | MEDLINE | ID: mdl-35425491

RESUMEN

Fine activated alumina (FAA) acting as an adsorbent for phosphate was synthesized from an industrial sodium aluminate solution based on phase evolution from Al(OH)3 and NH4Al(OH)2CO3. This material was obtained in the form of γ-Al2O3 with an open mesoporous structure and a specific surface area of 648.02 m2 g-1. The phosphate adsorption capacity of the FAA gradually increased with increases in phosphate concentration or contact time. The maximum adsorption capacity was 261.66 mg g-1 when phosphate was present as H2PO4 - at a pH of 5.0. A removal efficiency of over 96% was achieved in a 50 mg L-1 phosphate solution. The adsorption of phosphate anions could be explained using non-linear Langmuir or Freundlich isotherm models and a pseudo-second-order kinetic model. Tetra-coordinate AlO4 sites acting as Lewis acids resulted in some chemisorption, while (O) n Al(OH)2 + (n = 4, 5, 6) Brønsted acid groups generated by the protonation of AlO4 or AlO6 sites in the FAA led to physisorption. Analyses of aluminum-oxygen coordination units using Fourier transform infrared and X-ray photoelectron spectroscopy demonstrated that physisorption was predominant. Minimal chemisorption was also verified by the significant desorption rate observed in dilute NaOH solutions and the high performance of the regenerated FAA. The high specific surface area, many open mesopores and numerous highly active tetra-coordinate AlO4 sites on the FAA all synergistically contributed to its exceptional adsorption capacity.

18.
Bull Environ Contam Toxicol ; 109(1): 163-168, 2022 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-35394141

RESUMEN

The hydrothermal hydrogen reduction process for treating high-iron bauxite residue (red mud) was investigated, and the optimum conditions of alumina extraction as well as the enrichment of iron minerals were verified by experiments. Results show that the surface magnetization of Al-goethite under the function of hydrogen reduction accelerates its conversion to hematite and/or magnetite. This conversion releases the substituted Al in goethite as well as the undigested gibbsite/boehmite and further enriches the iron content in residue. After hydrothermal hydrogen reduction with H2/Red mud ratio of 0.085 mol/20 g at 270°C for 60 min, the alumina relative recovery ratio reaches 95.40% and the grade of iron (total iron in the form of iron element) in the residue can be enriched to 55.85%. Further, co-processing of the obtained iron-rich residue in the steel industry can achieve a significant reduction of red mud discharge.


Asunto(s)
Óxido de Aluminio , Hidrógeno , Hierro/química
19.
Bull Environ Contam Toxicol ; 109(1): 20-29, 2022 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-35088100

RESUMEN

Bauxite residue is a highly alkaline waste from alumina refining, and is mainly disposed by stacking with high environmental risks. Here, the migration of alkaline constituents and the restoration evaluation with phosphogypsum were discussed by soil column experiments to investigate the alkaline regulation in bauxite residue disposal areas (BRDAs). The pH, free alkali, exchangeable sodium in the top layer (0-25 cm depth) covered with BR and phosphogypsum mixtures were reduced from 10.89 ± 0.02, 285.45 ± 21.15 mmol/kg, 385.63 ± 30.34 mg/kg to 9.00 ± 0.50, 12.50 ± 1.50 mmol/kg, 97.00 ± 10.50 mg/kg. For the sublayers, including depths of 35, 45, 55 cm, these values dropped to 9.86, 10.06, 10.03; 38.23, 86.12, 148.00 mmol/kg; 152.90, 246.00, 305.00 mg/kg, respectively. These results indicated alkaline indicators for phosphogypsum amended BR declined dramatically, and the parameters for sublayers were also decreased due to the migration of alkaline constituents. The physicochemical properties for amended BR could meet the conditions for plant growth. This research provided a reference for alkalinity regulation in BRDAs by phosphogypsum.


Asunto(s)
Óxido de Aluminio , Suelo , Desarrollo de la Planta , Suelo/química
20.
Org Lett ; 23(24): 9543-9547, 2021 12 17.
Artículo en Inglés | MEDLINE | ID: mdl-34860537

RESUMEN

Nickel-catalyzed arylcarbamoylation reactions of alkenes of N-(o-haloaryl)acrylamides with CO and nitroarenes via reductive aminocarbonylation to produce carbamoyl-substituted oxindoles with an all-carbon quaternary stereogenic center are presented. Starting with N-(o-haloaryl)acrylamides, simple CO, and inexpensive nitroarenes and using a Ni catalyst, a dinitrogen-based ligand, a Zn reductant, a TMSCl additive, and a base system, this protocol enables the synthesis of various carbamoyl-substituted oxindoles and allows the efficient late-stage derivatization of valuable molecules.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA