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2.
Nanotechnology ; 35(20)2024 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-38320322

RESUMO

The increasing use of nanomaterials in consumer products is expected to lead to environmental contamination sometime soon. As water pollution is a pressing issue that threatens human survival and impedes the promotion of human health, the search for adsorbents for removing newly identified contaminants from water has become a topic of intensive research. The challenges in the recyclability of contaminated water continue to campaign the development of highly reusable catalysts. Although exfoliated 2D MXene sheets have demonstrated the capability towards water purification, a significant challenge for removing some toxic organic molecules remains a challenge due to a need for metal-based catalytic properties owing to their rapid response. In the present study, we demonstrate the formation of hybrid structure AuNPs@MXene (Mo2CTx) during the sensitive detection of Au nanoparticle through MXene sheets without any surface modification, and subsequently its applications as an efficient catalyst for the degradation of 4-nitrophenol (4-NP), methyl orange (MO), and methylene blue (MB). The hybrid structure (AuNPs@MXene) reveals remarkable reusability for up to eight consecutive cycles, with minimal reduction in catalytic efficiency and comparable apparent reaction rate constant (Kapp) values for 4-NP, MB, and MO, compared to other catalysts reported in the literature.

3.
iScience ; 27(2): 108920, 2024 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-38352227

RESUMO

Rapid industrialization and untreated industrial effluents loaded with toxic and carcinogenic contaminants, especially dyes that discharge into environmental waters, have led to a rise in water pollution, with a substantial adverse impact on marine life and humankind. Photocatalytic techniques are one of the most successful methods that help in degradation and/or removal of such contaminants. In recent years, semiconductor quantum dots are being substituted by carbon dots (CDs) as photocatalysts, due to the ease of formation, cost-effectiveness, possible sustainability and scalability, much lower toxicity, and above all its high capacity to harvest sunlight (UV, visible, and near infrared) through electron transfer that enhances the lifetime of the photogenerated charge carriers. A better understanding between the properties of the CDs and their role in photocatalytic degradation of dyes and contaminants is required for the formation of controllable structures and adjustable outcomes. The focus of this review is on CDs and its composites as photocatalysts obtained from different sustainable green as well as chemical precursors. Apart from the synthesis, characterization, and properties of the CDs, the study also highlights the effect of different parameters on the photocatalytic properties of CDs and their composites for catalytic dye degradation mechanisms in detail. Besides the present research development in the field, potential challenges and future perspectives are also presented.

4.
Sci Total Environ ; 920: 170991, 2024 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-38365028

RESUMO

Heavy metal-rich environments can promote the selection of metal-resistance genes (MRGs) in bacteria, often leading to the simultaneous selection of antibiotic-resistance genes (ARGs) through a process known as co-selection. To comprehensively evaluate the biological pollutants at electronic-waste (e-waste) recycling facilities, air, soil, and river samples were collected at four distinct Swiss e-waste recycling facilities and analyzed for ARGs, MRGs, mobile genetic elements (MGEs), endotoxins, and bacterial species, with correlations drawn to heavy metal occurrence. To our knowledge, the present work marks the first attempt to quantify these bio-pollutants in the air of e-waste recycling facilities, that might pose a significant health risk to workers. Although ARG and MRG's profiles varied among the different sample types, intl1 consistently exhibited high relative abundance rates, identifying it as the predominant MGE across all sample types and facilities. These findings underscore its pivol role in driving diverse bacterial adaptations to extreme heavy metal exposure by selection and dissemination of ARGs and MRGs. All air samples exhibited consistent profiles of ARGs and MRGs, with blaTEM emerging as the predominant ARG, alongside pbrT and nccA as the most prevalent MRGs. However, one facility, engaged in batteries recycling and characterized by exceptionally high concentrations of heavy metals, showcased a more diverse resistance gene profile, suggesting that bacteria in this environment required more complex resistance mechanisms to cope with extreme metal exposure. Furthermore, this study unveiled a strong association between gram-negative bacteria and ARGs and less with MRGs. Overall, this research emphasizes the critical importance of studying biological pollutants in the air of e-waste recycling facilities to inform robust safety measures and mitigate the risk of resistance gene dissemination among workers. These findings establish a solid foundation for further investigations into the complex interplay among heavy metal exposure, bacterial adaptation, and resistance patterns in such distinctive ecosystems.


Assuntos
Resíduo Eletrônico , Poluentes Ambientais , Metais Pesados , Humanos , Antibacterianos/farmacologia , Genes Bacterianos , Ecossistema , Bactérias/genética , Metais Pesados/toxicidade
5.
Environ Pollut ; 336: 122404, 2023 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-37625772

RESUMO

Antimicrobial resistance (AMR) is a serious issue that is continuously growing and spreading, leading to a dwindling number of effective treatments for infections that were easily treatable with antibiotics in the past. Animal farms are a major hotspot for AMR, where antimicrobials are often overused, misused, and abused, in addition to overcrowding of animals. In this study, we investigated the risk of AMR transmission from a farm to nearby residential areas by examining the overall occurrence of endotoxins, antibiotic resistance genes (ARGs), and mobile genetic elements (MGEs) in the air of a cattle farm. We assessed various factors, including the season and year, day and nighttime, and different locations within the farm building and its vicinity. The most abundant ARGs detected were tetW, aadA1, and sul2, genes that encode for resistances towards antibiotics commonly used in veterinary medicine. While there was a clear concentration gradient for endotoxin from the middle of the farm building to the outside areas, the abundance of ARGs and MGEs was relatively uniform among all locations within the farm and its vicinity. This suggests that endotoxins preferentially accumulated in the coarse particle fraction, which deposited quickly, as opposed to the ARGs and MGEs, which might concentrate in the fine particle fraction and remain longer in the aerosol phase. The occurrence of the same genes found in the air samples and in the manure indicated that ARGs and MGEs in the air mostly originated from the cows, continuously being released from the manure to the air. Although our atmospheric dispersion model indicated a relatively low risk for nearby residential areas, farm workers might be at greater risk of getting infected with resistant bacteria and experiencing overall respiratory tract issues due to continuous exposure to elevated concentrations of endotoxins, ARGs and MGEs in the air of the farm.


Assuntos
Endotoxinas , Genes Bacterianos , Animais , Bovinos , Fazendas , Endotoxinas/genética , Antibacterianos/farmacologia , Esterco/microbiologia , Resistência Microbiana a Medicamentos/genética , Alemanha , Sequências Repetitivas Dispersas
6.
Int J Oral Maxillofac Surg ; 52(12): 1282-1285, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37550130

RESUMO

This report highlights the role of local amphotericin B (AMB) injection in cases of maxillary mucormycosis. The COVID-19 pandemic has resulted in a dramatic rise in the number of rhino-orbital mucormycosis cases. Although extensive surgical debridement remains the gold standard treatment, tissue salvage is desirable. The cases of two patients treated with local AMB are reported here, indicating that early intervention for maxillary fungal sinusitis in the form of local AMB may avoid the need for more invasive treatment.


Assuntos
Sinusite Maxilar , Mucormicose , Doenças Orbitárias , Sinusite , Humanos , Anfotericina B/uso terapêutico , Mucormicose/tratamento farmacológico , Mucormicose/microbiologia , Antifúngicos/uso terapêutico , Sinusite Maxilar/tratamento farmacológico , Pandemias , Sinusite/tratamento farmacológico , Doenças Orbitárias/tratamento farmacológico
7.
AJNR Am J Neuroradiol ; 44(8): 934-938, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37414456

RESUMO

BACKGROUND: Transophthalmic artery embolization of intracranial meningiomas is thought to be associated with a high complication risk. PURPOSE: With advances in endovascular techniques, we systematically reviewed the current literature to improve our understanding of the safety and efficacy of transophthalmic artery embolization of intracranial meningiomas. DATA SOURCES: We performed a systematic search using PubMed from inception until August 3, 2022. STUDY SELECTION: Twelve studies with 28 patients with intracranial meningiomas embolized through the transophthalmic artery were included. DATA ANALYSIS: Baseline and technical characteristics and clinical and safety outcomes were collected. No statistical analysis was conducted. DATA SYNTHESIS: The average age of 27 patients was 49.5 (SD, 13) years. Eighteen (69%) meningiomas were located in the anterior cranial fossa, and 8 (31%), in the sphenoid ridge/wing. Polyvinyl alcohol particles were most commonly (n = 8, 31%) used to preoperatively embolize meningiomas, followed by n-BCA in 6 (23%), Onyx in 6 (23%), Gelfoam in 5 (19%), and coils in 1 patient (4%). Complete embolization of the target meningioma feeders was reported in 8 (47%) of 17 patients; partial embolization, in 6 (32%); and suboptimal embolization, in 3 (18%). The endovascular complication rate was 16% (4 of 25), which included visual impairment in 3 (12%) patients. LIMITATIONS: Selection and publication biases were limitations. CONCLUSIONS: Transophthalmic artery embolization of intracranial meningiomas is feasible but is associated with a non-negligible complication rate.


Assuntos
Embolização Terapêutica , Neoplasias Meníngeas , Meningioma , Humanos , Adulto , Meningioma/terapia , Neoplasias Meníngeas/terapia , Cuidados Pré-Operatórios/métodos , Embolização Terapêutica/métodos , Artérias , Resultado do Tratamento , Estudos Retrospectivos
8.
J Cancer Res Clin Oncol ; 149(10): 7717-7728, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37004598

RESUMO

AIM: To summarise our centre's experience managing patients with neuroendocrine tumours (NETs) in the first 5 years after the introduction of peptide receptor radionuclide therapy (PRRT) with [177Lu]Lu-DOTA-octreotate (LUTATE). The report emphasises aspects of the patient management related to functional imaging and use of radionuclide therapy. METHODS: We describe the criteria for treatment with LUTATE at our centre, the methodology for patient selection, and the results of an audit of clinical measures, imaging results and patient-reported outcomes. Subjects are treated initially with four cycles of ~ 8 GBq of LUTATE administered as an outpatient every 8 weeks. RESULTS: In the first 5 years offering LUTATE, we treated 143 individuals with a variety of NETs of which approx. 70% were gastroentero-pancreatic in origin (small bowel: 42%, pancreas: 28%). Males and females were equally represented. Mean age at first treatment with LUTATE was 61 ± 13 years with range 28-87 years. The radiation dose to the organs considered most at risk, the kidneys, averaged 10.6 ± 4.0 Gy in total. Median overall survival (OS) from first receiving LUTATE was 72.5 months with a median progression-free survival (PFS) of 32.3 months. No evidence of renal toxicity was seen. The major long-term complication seen was myelodysplastic syndrome (MDS) with a 5% incidence. CONCLUSIONS: LUTATE treatment for NETs is a safe and effective treatment. Our approach relies heavily on functional and morphological imaging informing the multidisciplinary team of NET specialists to guide appropriate therapy, which we suggest has contributed to the favourable outcomes seen.


Assuntos
Tumores Neuroendócrinos , Masculino , Feminino , Humanos , Adulto , Pessoa de Meia-Idade , Idoso , Idoso de 80 Anos ou mais , Tumores Neuroendócrinos/patologia , Medicina de Precisão , Octreotida/uso terapêutico , Imagem Molecular , Receptores de Peptídeos , Radioisótopos
9.
Med Oral Patol Oral Cir Bucal ; 28(2): e99-e107, 2023 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-36806020

RESUMO

BACKGROUND: Coronavirus disease 2019 (COVID-19) in the recent times have instilled signs of immunosuppression globally which has further precipitated increasing range of opportunistic infections. Mucormycosis is a distressing opportunistic fungal infection with a high incidence and is the third commonest acute invasive infection following candidiasis and aspergillosis. The aim of the present observational study is to delineate the enigmatic histopathological profile between mucormycosis cases seen prior to pandemic (PPM) and pandemic associated mucormycosis (PAM). MATERIAL AND METHODS: Tissue archives of 105 histopathologically diagnosed cases of mucormycosis were included and analysed for demographical details and histopathological parameters like fungal load and localization, granuloma formation, necrosis, inflammatory infiltrate and tissue invasion. RESULTS: 0ut of 105 included cases, 11/105 (10.48%) were reported PPM and 94/105 (89.52%) PAM. Among 94 cases of PAM, 51/94 (54%) cases also showed COVID-19 positivity, while 43/94 (46%) did not. Of all the histological variables, increased fungal load and necrosis were observed in PAM relative to PPM cases. CONCLUSIONS: The histopathological variables like fungal load, necrosis, granuloma formation and tissue invasion, could help the clinician in assessing the clinical status at the time of tissue diagnosis and improve the treatment accordingly.


Assuntos
COVID-19 , Mucormicose , Humanos , Mucormicose/diagnóstico , Mucormicose/tratamento farmacológico , Mucormicose/epidemiologia , Pandemias , COVID-19/epidemiologia , Necrose/complicações , Necrose/epidemiologia , Granuloma
11.
AJNR Am J Neuroradiol ; 44(1): 95-104, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36549846

RESUMO

BACKGROUND AND PURPOSE: A high-intensity zone identified on preprocedural MR imaging is known to correlate with pain at provocation lumbar discography. The correlation between enhancing annular fissures and pain at provocation lumbar discography has not been comprehensively evaluated. The purpose of this study was to assess the pain response and imaging features at enhancing annular fissure nonoperated disc levels identified on preprocedural MR imaging with comparison with the high-intensity zone and nonenhancing disc levels in patients referred for provocation lumbar discography. MATERIALS AND METHODS: One-hundred nonoperated discs in 44 patients were retrospectively evaluated for an enhancing annular fissure on sagittal postcontrast T1-weighted pre-discogram MR imaging. Enhancing annular fissure discs were graded on the sagittal T2-weighted sequence (Grade 4: like CSF to Grade 1: negative/barely visible) for high-intensity-zone conspicuity. High-intensity-zone detection was performed independently. In the primary assessment, enhancing annular fissure and high-intensity zones were associated with pain response at provocation lumbar discography. Additional analysis included intradiscal anesthetic response and postdiscogram CT appearance. RESULTS: Thirty-nine discs demonstrated an enhancing annular fissure, with 23/39 demonstrating a high-intensity zone. The presence of a high-intensity zone predicted severe pain (concordant + nonconcordant; P = .005, sensitivity of 40%, specificity of 94%) and concordant pain (P = .007, sensitivity of 39%, specificity of 86%) at provocation lumbar discography. Enhancing annular fissures without a detected high-intensity zone were more frequently observed among severely painful (50%) and concordant (36%) discs than among discs negative for pain (9%; P = .01). This finding resulted in a substantially greater overall sensitivity of enhancing annular fissures for severe (P < .001, 64%) and concordant pain (P = .008, 61%), significantly improving the overall predictive ability of a high-intensity zone alone. A high-intensity zone went undetected in 9/11 Grade 1 disc levels with concordant pain present in 7/9. CONCLUSIONS: Consideration of enhancing annular fissures on preprocedural MR imaging substantially improves the prediction of severe/concordant pain in provocation lumbar discography.


Assuntos
Anestésicos , Deslocamento do Disco Intervertebral , Disco Intervertebral , Dor Lombar , Humanos , Disco Intervertebral/diagnóstico por imagem , Dor Lombar/diagnóstico , Dor Lombar/etiologia , Estudos Retrospectivos , Vértebras Lombares/diagnóstico por imagem , Imageamento por Ressonância Magnética
12.
Diabetes Res Clin Pract ; 182: 109115, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34718051

RESUMO

AIMS: UCP1 and PRDM16 genes, primarily involved in browning of adipose tissue that can affect lipid metabolism are also associated with diabetes risk. Therefore, we planned to study the adipose tissue expression of UCP1 and PRDM 16 genes in subjects with glucose intolerance to find out its association with postprandial triglyceride (PPTg) measures and T2DM. METHODS: A total of 30 subjects were recruited in three groups i.e., NGT, prediabetes and T2DM (NDDM + known T2DM) who were matched for age, sex and BMI. An 8-hour standardized fat challenge test was performed to study lipemic responses. UCP1 and PRDM16 genes quantification in adipose tissue was performed by real-time PCR followed by SDS PAGE. RESULTS: UCP1 gene expression in SAT was significantly lower in T2DM and prediabetes as compared to NGT group while PRDM16 gene expression was significantly lower in T2DM group as compared to NGT group. UCP1 gene expression correlated with PPTg measures as well as with glycaemic measures while PRDM16 gene expression correlated with glycaemic measures only. CONCLUSION: This study found downregulation of PRDM16 and UCP1 gene expression in SAT in subjects with glucose intolerance. The association of UCP1 gene expression with PPTg dysmetabolism may contribute to greater predisposition to T2DM.


Assuntos
Intolerância à Glucose , Proteína Desacopladora 1 , Tecido Adiposo , Proteínas de Ligação a DNA/genética , Intolerância à Glucose/genética , Humanos , Metabolismo dos Lipídeos , Fatores de Transcrição/genética , Triglicerídeos , Proteína Desacopladora 1/metabolismo
14.
Nanotechnology ; 32(38)2021 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-34010824

RESUMO

We report the fabrication of nitrogen-doped carbon dots-zinc oxide hybrid (NCDs-ZnO) nanostructures utilizing simple chemical procedures. The role of NCDs in ZnO nanostructured matrix has been analyzed through XRD, SEM, FTIR and PL characterization techniques. The introduction of NCDs was found to modify not only their aspect ratio, observed by a reduction in the preferredc-axis growth compared to thea- andb-axis, but also induced an additional emission around 441 nm, which is typical of NCDs. The hybrid nanostructures were utilized as catalyst for methylene blue dye degradation showing a 95% degradation after 2 h of UV irradiation in comparison to the ∼70% degradation obtained by utilizing pristine ZnO, while the dye half-life (t1/2) was reduced by ∼65% by utilizing NCDs-ZnO hybrid nanostructures when compared to the pristine ZnO. The reusability of the fabricated hybrid structures was tested up to eight times with no significant loss in their photocatalytic performance (>90%). The stability of the hybrid structures was verified through Z-potential measurements prior and after reutilization. Excellent reusability and simple processing presented by NCDs-ZnO hybrid nanostructures makes them promising for industrial level photocatalyst for the waste water treatment.

15.
Clin Radiol ; 76(4): 314.e17-314.e23, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33526255

RESUMO

AIM: To analyse the technical challenges, clinical success, and associated complications of endovascular and percutaneous embolisation of pancreatitis-related pseudoaneurysms. MATERIALS AND METHODS: A retrospective study of patients referred for embolisation of pancreatitis-related pseudoaneurysms between January 2014 and March 2019 was conducted. Computed tomography angiography (CTA) was performed to assess the morphology of the aneurysms prior to any intervention. Percutaneous or endovascular embolisation was performed. Details of CTA and methods of embolisation were recorded. Technical success, clinical success, and complications were reported. RESULTS: A total of 80 patients (mean age, 40.69 ± 13.41 years, 73 male) underwent embolisation during the study period. Pseudoaneurysms were related to chronic pancreatitis (CP) in 44 (55%) patients and acute pancreatitis (AP) in 36 (45%) patients. Pseudoaneurysms were detected in 65 (81.2%) patients on CTA. The most common site of pseudoaneurysms was gastroduodenal artery (GDA) followed by splenic artery. Seven patients were treated with percutaneous thrombin injection and five were treated with percutaneous glue injection under ultrasound/fluoroscopy guidance. The remaining patients (n=68) underwent catheter angiography with endovascular embolisation. Technical success was achieved in 4/7 (57%) percutaneous thrombin cases and in all the cases (5/5, 100%) with percutaneous glue or endovascular (68/68,100%) embolisation. CONCLUSION: Endovascular or percutaneous embolisation of pseudoaneurysms has high technical success with an excellent safety profile.


Assuntos
Falso Aneurisma/terapia , Embolização Terapêutica/métodos , Procedimentos Endovasculares/métodos , Pancreatite/complicações , Doença Aguda , Adolescente , Adulto , Idoso , Falso Aneurisma/diagnóstico por imagem , Falso Aneurisma/etiologia , Artérias/diagnóstico por imagem , Criança , Angiografia por Tomografia Computadorizada , Duodeno/irrigação sanguínea , Embolização Terapêutica/efeitos adversos , Procedimentos Endovasculares/efeitos adversos , Feminino , Adesivo Tecidual de Fibrina/administração & dosagem , Artéria Gástrica/diagnóstico por imagem , Humanos , Índia , Masculino , Pessoa de Meia-Idade , Pancreatite Crônica/complicações , Recidiva , Estudos Retrospectivos , Artéria Esplênica/diagnóstico por imagem , Centros de Atenção Terciária , Trombina/administração & dosagem , Adulto Jovem
16.
Anaesthesia ; 76(4): 520-536, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33027841

RESUMO

This international multidisciplinary consensus statement was developed to provide balanced guidance on the safe peri-operative use of opioids in adults. An international panel of healthcare professionals evaluated the literature relating to postoperative opioid-related harm, including persistent postoperative opioid use; opioid-induced ventilatory impairment; non-medical opioid use; opioid diversion and dependence; and driving under the influence of prescription opioids. Recommended strategies to reduce harm include pre-operative assessment of the risk of persistent postoperative opioid use; use of an assessment of patient function rather than unidimensional pain scores alone to guide adequacy of analgesia; avoidance of long-acting (modified-release and transdermal patches) opioid formulations and combination analgesics; limiting the number of tablets prescribed at discharge; providing deprescribing advice; avoidance of automatic prescription refills; safe disposal of unused medicines; reducing the risk of opioid diversion; and better education of healthcare professionals, patients and carers. This consensus statement provides a framework for better prescribing practices that could help reduce the risk of postoperative opioid-related harm in adults.


Assuntos
Analgésicos Opioides/efeitos adversos , Transtornos Relacionados ao Uso de Opioides/prevenção & controle , Analgésicos Opioides/uso terapêutico , Humanos , Transtornos Mentais/complicações , Transtornos Relacionados ao Uso de Opioides/etiologia , Dor Pós-Operatória/complicações , Dor Pós-Operatória/tratamento farmacológico , Cuidados Pós-Operatórios , Uso Excessivo de Medicamentos Prescritos , Fatores de Risco
17.
Sci Rep ; 10(1): 8555, 2020 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-32444609

RESUMO

We present a spectroscopic ellipsometry study of Mo-doped VO2 thin films deposited on silicon substrates for the mid-infrared range. The dielectric functions and conductivity were extracted from analytical fittings of Ψ and Δ ellipsometric angles showing a strong dependence on the dopant concentration and the temperature. Insulator-to-metal transition (IMT) temperature is found to decrease linearly with increasing doping level. A correction to the classical Drude model (termed Drude-Smith) has been shown to provide excellent fits to the experimental measurements of dielectric constants of doped/undoped films and the extracted parameters offer an adequate explanation for the IMT based on the carriers backscattering across the percolation transition. The smoother IMT observed in the hysteresis loops as the doping concentration is increased, is explained by charge density accumulation, which we quantify through the integral of optical conductivity. In addition, we describe the physics behind a localized Fano resonance that has not yet been demonstrated and explained in the literature for doped/undoped VO2 films.

18.
Waste Manag ; 107: 66-73, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-32278217

RESUMO

Efficient recovery of REEs present in the battery waste is a modern problem that has proven to be difficult to solve in an efficient manner. The raw material investigated in the current study is mixed alkaline rare earth element (REE) double sulfate (DS) precipitate, originating from the sulfuric acid leachate of nickel-metal hydride battery (NiMH) waste. Typically, REE can be precipitated as a mixture of REE double sulfates, however the real challenge is the separation of REEs from each other's into pure fraction. The study elucidates the process by which the DS are transformed into hydroxides with simultaneous in-situ conversion of Ce(III) to Ce(IV) by air. Air flow rate (0-1 L/h), temperature (30-60 °C), liquid-solid ratio (L/S, 12.5-100 g/L), 3REE/NaOH mol ratio (1-1.6) and time (60-240 min) were varied in the study of oxidation and double sulfate conversion. Best oxidation achieved was 93% along near-complete dissociation of double sulfate matrix (52767 ppm Na reduced to 48 ppm Na). After parameter optimization, a larger batch was produced to conduct selective dissolution of REE(III) into HNO3 media, leaving concentrated impure Ce(OH)4 as the end product.


Assuntos
Metais Terras Raras , Níquel , Hidrólise , Metais , Sulfatos
19.
Ultrasonics ; 108: 106113, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32278501

RESUMO

A novel experimental technique based on point contact and Coulomb coupling is devised and optimized for ultrasonic imaging of bulk and guided waves propagation in piezo-ceramics. The Coulomb coupling technique exploits the coupling and transfer of electric field to mechanical vibrations by excitation of phonons. The point contact excitation and detection technique facilitates the spatial-temporal imaging of ultrasonic waves. The motivation of this research is the diagnosis and localization of surface cracks in the piezoelectric sensors and actuators. The underlying principle of the detection scheme is that any discontinuity on the surface causes high localization of electric gradient. The localized electric field at the defect boundaries enables then to behave as secondary passive ultrasonic sources resulting in strong back reflections. However, due to the interference between transmitted and reflected wave components from rigid boundaries and defect, the resolution on the localization of the damage is challenging. Therefore, an algorithm based on the two-dimensional spectral decomposition is utilized for selective suppression of the transmitted wave. The algorithm includes data transformation and vectorization in polar coordinates for efficient spectral decomposition. In the spectral domain, the complex wave component (phase and amplitude) are suppressed for the transmitted wave field. The reflected wave component in the spectral domain is retained and retrieved back using inverse spectral transformation. The algorithm is successful in retaining and exemplifying only the reflected wave sources arising from the strong scattering of ultrasonic waves from the surface and sub-surface defects. In summary, a novel experimental technique based on Coulomb coupling and spectral decomposition technique has been implemented for localization of surface defect in piezo-ceramic structures.

20.
RSC Adv ; 10(38): 22522-22532, 2020 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-35514557

RESUMO

Methanol (MeOH) adulteration in alcoholic beverages resulting in irreparable health damage demands highly sensitive and cost-effective sensors for its quantification. As carbon dots are emerging as new biocompatible and sustainable light-emitting detectors, this work demonstrates the hydrothermally prepared nitrogen-doped oxidized carbon dots (NOCDs) as on-off fluorescent nanoprobes to detect MeOH traces in water and alcoholic beverages. The presence of 1% of MeOH in distilled water is found to decrease the NOCD fluorescent emission intensity by more than 90% whereas up to 70% ethanol (EtOH) content changes the signal to within 20% of its initial value. HR-TEM analysis reveals the agglomeration of the nanoprobes suspended in MeOH. Due to their selectivity towards MeOH, the fluorescent nanoprobes were successfully tested using a few MeOH spiked branded and unbranded Mexican alcoholic beverages. Varying degrees of signal quenching is observed from the fluorescent nanoprobes dispersed in different pristine beverages with a detection limit of less than 0.11 v%. Herein, we establish a new perspective towards economically viable non-toxic fluorescent probes as a potential alternative for the detection of MeOH in alcoholic beverages.

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