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3.
Actas Dermosifiliogr ; 113(1): T78-T81, 2022 Jan.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-35249719

RESUMO

Malassezia folliculitis is an under-recognized entity commonly affecting the face and upper trunk. Clinical picture mimics acne vulgaris and diagnosis is challenging at times. Ten percent potassium hydroxide examination is usually performed to confirm the diagnosis. This study sought to describe the dermoscopic features in Malassezia folliculitis. Patients diagnosed clinically with Malassezia folliculitis and confirmed by 10% potassium hydroxide preparation were included in the study. Dermoscopy was performed with a videodermatoscope (Dino-Lite AM413ZT; Polarizer) from the most representative lesion. A total of 45 patients (M:F=1:0.8) were recruited. All patients had monomorphic papulo-pustular lesions. Itching was present in 64.4% patients. Dermoscopy reveled folliculocentricity (100%), perilesional background erythema (100%), dotted/linear/tortous vessels (88.9%), dirty white scaling (77.8%), hypopigmentation of hair follicle (64.4%), coiled/looped hairs (57.8%) and broken hairs (13.3%). In conclusion, dermoscopy shows typical features in Malassezia folliculitis and can serve as a office-based tool for identification of this entity.

4.
Actas Dermosifiliogr ; 113(1): 78-81, 2022 Jan.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-35244544

RESUMO

Malassezia folliculitis is an under-recognizedentity commonly affecting the face and upper trunk. Clinical picture mimics acne vulgaris and diagnosis is challenging at times. 10% potassium hydroxide examination is usually performed to confirm the diagnosis. This study sought to describe the dermoscopic features in Malassezia folliculitis. Patients diagnosed clinically with Malassezia folliculitis and confirmed by 10% potassium hydroxide preparation were included in the study. Dermoscopy was performed with a videodermatoscope [Dinolite AM413ZT; Polarising] from the most representative lesion. A total of 45 patients (M:F = 1:0.8 ) were recruited. All patients had monomorphic papulo-pustular lesions. Itching was present in 64.4% patients. Dermoscopy reveled folliculocentricity (100%), perilesional background erythema (100%), dotted/linear/tortous vessels (88.9%), dirty white scaling (77.8%), hypo pigmentation of hair follicle (64.4%), coiled/looped hairs (57.8%) and broken hairs (13.3%). In conclusion, dermoscopy shows typical features in Malassezia folliculitis and can serve as a office based tool for identification of this entity.

5.
Actas dermo-sifiliogr. (Ed. impr.) ; 113(1): 78-81, Ene. 2022. ilus
Artigo em Inglês | IBECS | ID: ibc-205279

RESUMO

Malassezia folliculitis is an under-recognizedentity commonly affecting the face and upper trunk. Clinical picture mimics acne vulgaris and diagnosis is challenging at times. 10% potassium hydroxide examination is usually performed to confirm the diagnosis. This study sought to describe the dermoscopic features in Malassezia folliculitis. Patients diagnosed clinically with Malassezia folliculitis and confirmed by 10% potassium hydroxide preparation were included in the study. Dermoscopy was performed with a videodermatoscope [Dinolite AM413ZT; Polarising] from the most representative lesion. A total of 45 patients (M:F = 1:0.8 ) were recruited. All patients had monomorphic papulo-pustular lesions. Itching was present in 64.4% patients. Dermoscopy reveled folliculocentricity (100%), perilesional background erythema (100%), dotted/linear/tortous vessels (88.9%), dirty white scaling (77.8%), hypo pigmentation of hair follicle (64.4%), coiled/looped hairs (57.8%) and broken hairs (13.3%). In conclusion, dermoscopy shows typical features in Malassezia folliculitis and can serve as a office based tool for identification of this entity (AU)


La foliculitis por Malassezia es una entidad que no está debidamente reconocida y que afecta normalmente a la cara y tronco superior. El cuadro clínico remeda el acné vulgar, siendo a veces difícil su diagnóstico. Normalmente se realiza un examen con hidróxido de potasio al 10% para confirmar el mismo. El objetivo de este estudio fue describir las características dermatoscópicas de la foliculitis por Malassezia, incluyéndose en el mismo a los pacientes diagnosticados clínicamente y confirmados mediante aplicación de hidróxido de potasio al 10%. La dermatoscopia fue realizada con un videodermatoscopio [Dinolite AM413ZT; Polarising] en la lesión más representativa. Se incluyó a un total de 45 pacientes (V:M = 1:0.8). Todos los pacientes tenían lesiones monomórficas papulopustulosas. El 64% de los pacientes presentó prurito. La dermatoscopia reveló foliculocentricidad (100%), eritema circundante perilesional (100%), vasos punteados/lineales/tortuosos (88,9%), escamas de color gris parduzco (77,8%), hipopigmentación del folículo piloso (64,4%), pelos en espiral/enrollados (57,8%) y rotura del pelo (13,3%). En conclusión, la dermatoscopia muestra las características típicas de la foliculitis por Malassezia, pudiendo servir de ayuda en consulta como herramienta para la identificación de esta entidad (AU)


Assuntos
Humanos , Masculino , Feminino , Criança , Adolescente , Adulto Jovem , Dermatomicoses/diagnóstico por imagem , Foliculite/diagnóstico por imagem , Foliculite/microbiologia , Malassezia , Dermoscopia
6.
Actas dermo-sifiliogr. (Ed. impr.) ; 113(1): t78-t81, Ene. 2022. ilus
Artigo em Espanhol | IBECS | ID: ibc-205280

RESUMO

La foliculitis por Malassezia es una entidad que no está debidamente reconocida y que afecta normalmente a la cara y tronco superior. El cuadro clínico remeda el acné vulgar, siendo a veces difícil su diagnóstico. Normalmente se realiza un examen con hidróxido de potasio al 10% para confirmar el mismo. El objetivo de este estudio fue describir las características dermatoscópicas de la foliculitis por Malassezia, incluyéndose en el mismo a los pacientes diagnosticados clínicamente y confirmados mediante aplicación de hidróxido de potasio al 10%. La dermatoscopia fue realizada con un videodermatoscopio [Dinolite AM413ZT; Polarising] en la lesión más representativa. Se incluyó a un total de 45 pacientes (V:M = 1:0.8). Todos los pacientes tenían lesiones monomórficas papulopustulosas. El 64% de los pacientes presentó prurito. La dermatoscopia reveló foliculocentricidad (100%), eritema circundante perilesional (100%), vasos punteados/lineales/tortuosos (88,9%), escamas de color gris parduzco (77,8%), hipopigmentación del folículo piloso (64,4%), pelos en espiral/enrollados (57,8%) y rotura del pelo (13,3%). En conclusión, la dermatoscopia muestra las características típicas de la foliculitis por Malassezia, pudiendo servir de ayuda en consulta como herramienta para la identificación de esta entidad (AU)


Malassezia folliculitis is an under-recognizedentity commonly affecting the face and upper trunk. Clinical picture mimics acne vulgaris and diagnosis is challenging at times. 10% potassium hydroxide examination is usually performed to confirm the diagnosis. This study sought to describe the dermoscopic features in Malassezia folliculitis. Patients diagnosed clinically with Malassezia folliculitis and confirmed by 10% potassium hydroxide preparation were included in the study. Dermoscopy was performed with a videodermatoscope [Dinolite AM413ZT; Polarising] from the most representative lesion. A total of 45 patients (M:F = 1:0.8 ) were recruited. All patients had monomorphic papulo-pustular lesions. Itching was present in 64.4% patients. Dermoscopy reveled folliculocentricity (100%), perilesional background erythema (100%), dotted/linear/tortous vessels (88.9%), dirty white scaling (77.8%), hypo pigmentation of hair follicle (64.4%), coiled/looped hairs (57.8%) and broken hairs (13.3%). In conclusion, dermoscopy shows typical features in Malassezia folliculitis and can serve as a office based tool for identification of this entity (AU)


Assuntos
Humanos , Masculino , Feminino , Criança , Adolescente , Adulto Jovem , Dermatomicoses/diagnóstico por imagem , Foliculite/diagnóstico por imagem , Foliculite/microbiologia , Malassezia , Dermoscopia
7.
Lett Appl Microbiol ; 74(2): 159-184, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34402087

RESUMO

Bacterial species capable of performing both nitrification and denitrification in a single vessel under similar conditions have gained significance in the wastewater treatment scenario considering their unique character of performing the above reactions under heterotrophic and aerobic conditions respectively. Such a novel strategy often referred to as simultaneous nitrification and denitrification (SND) has a tremendous potential in dealing with various wastewaters having low C : N content, considering that the process needs very little or no external carbon source and oxygen supply thus adding to its cost-effective and environmentally friendly nature. Though like other micro-organisms, heterotrophic nitrifiers and aerobic denitrifiers convert inorganic or organic nitrogen-containing substances into harmless dinitrogen gas in the wastewater, their ecophysiological role in the global nitrogen cycle is still not fully understood. Attempts to highlight the role played by the heterotrophic nitrifiers and aerobic denitrifiers in dealing with nitrogen pollution under various environmental operating conditions will help in developing a mechanistic understanding of the SND process to address the issues faced by the traditional methods of aerobic autotrophic nitrification-anaerobic heterotrophic denitrification.


Assuntos
Nitrificação , Purificação da Água , Aerobiose , Desnitrificação , Nitrogênio , Águas Residuárias
8.
J Phys Condens Matter ; 34(1)2021 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-34614485

RESUMO

The optical properties of graphene in monolayer and bilayer structure is essential for the development of optical devices viz surface plasmon resonance (SPR) based bio-sensors. The band structure of the twisted bilayer graphene (BLG) is remarkably different than the normal AA or AB stacking. This provides an opportunity to control the optical and electrical properties of BLG by applying an in-plane twist to one of the layer relative to other in a BLG system. Here, we calculated the refractive index (RI) of AA and AB stacking of BLG system using density functional theory. Though the spectrum for AA stacking shows some similarity with that of monolayer graphene, the spectrum for AB stacking was found to be remarkably different. The spectrum of AB stacked layer is red-shifted and the absorption peaks in low energy regime increases nearly by three-folds. A large dependency of the twist angle on RI of twisted BLG were found. Based on the calculation, a schematic of phase diagram showing material behavior of such twisted BLG systems as a function of twist angle and photon energy was constructed. The twisted AA stacked BLG shows largely dielectric behavior whereas the twisted AB stacked BLG shows predominately semimetallic and semiconducting behavior. This study presents a RI landscape of twisted BLG dependent on important parameters viz photon energy and inplane relative twist angle. Our studies will be very useful for the design and development of optical devices employing BLG systems particularly SPR based bio-sensors which essentially measures change in RI due to adsorption of analytes.

9.
Malays Orthop J ; 15(2): 12-17, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34429817

RESUMO

INTRODUCTION: Bone-patellar tendon-bone (BPTB) and semitendinosus-gracilis (STG) are the commonest grafts used for ACL reconstruction. However even after having been debated for years, there is no consensus about the ideal graft. Moreover, the literature is deficient about STG graft with preserved tibial insertion (STGPI) which preserves the proprioception. Our aim is to compare the outcome of BPTB, free STG and STGPI grafts after ACL reconstruction in professional sports persons. We compared the outcome in terms of mechanical stability, functional outcome, return to sports activity and degenerative changes. MATERIAL AND METHODS: Professional sports persons aged between 16-50 years operated for ACL tear using BPTB, free STG and STGPI grafts with minimum follow-up of two years were identified from hospital records. Patients with associated knee injuries were excluded. Patients, divided in three groups according to graft used, were compared in terms of mechanical stability (arthrometric examination KT-1000 score), functional outcome (Lysholm Score), return to sports activity (Tegner score and difference in thigh circumference) and degenerative changes (KL grading). RESULTS: BPTB graft group was found to be better than free STG and STGPI graft groups in terms of KT-1000 score. There was no statistically significant difference among the groups in terms of Lysholm score, Tegner score, difference in thigh circumference and KL grading. CONCLUSION: BPTB graft is better than free STG and STGPI grafts in terms of knee stability. When compared for patient reported outcome, return to sports activity, osteoarthritic changes and graft failure there is no significant difference among the three types of grafts.

10.
Urban Clim ; 39: 100945, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34377634

RESUMO

The present study deals with the impact of the pandemic outbreak of COVID-19 on the ambient air quality in the capital city of India. Real-time data were collected from eight continuous ambient air quality monitoring stations measuring important air quality parameters (NO2, PM10 and PM2.5). Results revealed that the city's air quality had improved significantly during the lockdown period due to COVID-19 outbreak. The concentration of gaseous and particulate matter during the lockdown period (March-May 2020) declined significantly compared with the preceding years' data from the same timeframe. However, the ambient air quality deteriorates with the onset of unlocking phases and post-monsoon season (October 2020). Higher concentration of NO2, PM10 and PM2.5 were recorded at industrial (S1 and S2) and hotspot (S4 and S5) sites. The lowest concentrations of studied pollutants were observed during the first phase of lockdown (March 24 - May 14, 2020). The present study, once again, establishes the direct effect of anthropogenic activities and deteriorating ambient air quality of Delhi.

11.
Indian J Pediatr ; 88(Suppl 1): 131-137, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33403615

RESUMO

OBJECTIVE: To determine the clinical and epidemiological profile of Intussusception in children aged <2 y after introduction of rotavirus vaccine in Universal Immunization Programme of Rajasthan. METHOD: This was a hospital-based multi-centric surveillance study conducted at three tertiary care sentinel sites in Rajasthan over a period of 2 y. Children <2 y of age admitted with intussusception as per Brighton's criteria 1 were enrolled. Demographic details including age, sex, clinical presentation, diagnostic methods, duration of symptoms, mode of treatment, and complications were recorded and analyzed. RESULTS: During the study period of 2 y, the authors identified 164 cases of intussusception based on level-1 Brighton's criteria. Median age at presentation was 7 mo [Interquartile range (IQR) 5-10 mo] with a male to female ratio of 2:1. Pain abdomen and blood stained stool were the commonest presenting complaints (88.4% and 81.7%, respectively). Commonest site of intussusception was Ileocolic (82.32%). Pathological lead point was identified in 18.9% cases. Distinct seasonality was observed as maximum cases of intussusception were detected in the months of Jan-March (34.1%). Surgical intervention was required in the 89.63% cases. The median time duration between onset of symptoms and admission at sentinel site was 2 d (IQR 1-3 d). Proportion of cases that required surgery increased as the time interval between onset of symptoms and admission increases. CONCLUSION: Intussusception is a common surgical condition among children under-two years of age with majority of cases occurring during infancy. Case management is dependent primarily on time duration elapsed between symptoms onset and admission to tertiary care centre. Early case detection and timely referral may provide an opportunity to avoid surgical interventions.


Assuntos
Intussuscepção , Infecções por Rotavirus , Vacinas contra Rotavirus , Idoso , Criança , Feminino , Humanos , Índia/epidemiologia , Lactente , Intussuscepção/diagnóstico , Intussuscepção/epidemiologia , Masculino , Estudos Retrospectivos
12.
Appl Opt ; 60(1): 89-97, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33362083

RESUMO

A decrease in photon intensity due to carbon contamination on optical elements is a serious issue in synchrotron radiation (SR) beamlines. Photon intensity can be regained by refurbishment of optical elements using suitable techniques. In the literature, three suitable techniques [radio frequency (RF) plasma, ultraviolet (UV) radiation (λ=172nm), and infrared (IR) laser (λ=1064nm) exposure] are reported to remove carbon contaminations from optical elements. These techniques are used independently to remove carbon, and, to the best of our knowledge, no systematic study is available on their relative efficiencies and effects on a mirror surface. We have applied these techniques independently for removal of carbon contamination from a gold surface, and detailed surface characterizations are carried out using soft x-ray reflectivity, x-ray photoelectron spectroscopy, Raman spectroscopy, and atomic force microscopy techniques. Characterization results suggest that all three techniques are capable of removing carbon contamination with certain limitations. Here, detailed relative effects on a gold surface after cleaning experiments with three techniques are discussed.

13.
Indian J Pediatr ; 88(Suppl 1): 90-96, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33247377

RESUMO

OBJECTIVES: To estimate the proportion of rotavirus diarrhea among hospitalized children aged under-five years, to determine the circulating rotavirus genotypes and to know impact rotavirus vaccine on prevalence and severity of rotavirus diarrhea. METHODS: This study was a hospital based cross-sectional observational study conducted over a period of 29 mo (September 2017 through January 2020). Stool samples were collected from children who fall within the age range of 0-59 mo with acute diarrhea attending emergency or needing admission. Stool samples were tested for rotavirus by the enzyme linked immune-sorbent assay (ELISA) and genotyped using published methods. RESULTS: Out of 1480 samples, 360 (24.32%) cases were positive for rotavirus by ELISA, majority of them were male (62.97%). Maximum rotavirus positivity was found in the age group of <11 mo (55.27%). Statistically significance difference was seen in episodes of diarrhea and experience of vomiting in rotavirus diarrhea cases. Highest prevalence has been seen during winter season. The most prevalent G and P type combinations were G3P [8] strains [122 (34.08%)], G2P [4] [83 (23.18%)], G1P [8] [27 (7.54%)] and G9P [4] [20 (5.59%)]. Mixed strains contribute a significant proportion of stool sample. CONCLUSIONS: Rotavirus is an important cause of diarrhea in hospitalized children. There is continued circulation of G9 and G12 strains and the emergence of G3P [8] as most common strain.


Assuntos
Gastroenterite , Infecções por Rotavirus , Rotavirus , Criança , Estudos Transversais , Diarreia/epidemiologia , Fezes , Feminino , Gastroenterite/epidemiologia , Genótipo , Humanos , Índia/epidemiologia , Lactente , Masculino , Epidemiologia Molecular , Prevalência , Rotavirus/genética , Infecções por Rotavirus/epidemiologia , Infecções por Rotavirus/prevenção & controle , Centros de Atenção Terciária , Vacinação
14.
Malays Orthop J ; 14(2): 120-125, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32983386

RESUMO

INTRODUCTION: To assess the results of Milch osteotomy in terms of deformity correction and functional outcome in the absence of ulnar nerve transposition. MATERIAL AND METHODS: Nine patients with cubitus valgus deformity greater than 20° with tardy ulnar nerve palsy (TUNP) operated between 2012 and 2017 were evaluated. Correction by Milch osteotomy and fixation was done in each case, without osteosynthesis of the non-union lateral condyle humerus or transposition of the ulnar nerve. At one year post-operatively, carrying angle, elbow function (Mayo Elbow Performance Score) and ulnar nerve symptoms were assessed. RESULTS: The mean carrying angle pre-operatively was 30.8° on the affected side which improved to a mean of 8.3° postoperatively with an average correction of 22.5°. The mean elbow flexion pre-operatively was 129.4° which improved to 133.3° post-operatively. The mean preoperative MEP score was 76.7 which improved to a mean of 92.2 post-operatively (p < 0.01). TUNP recovered completely in all the patients. CONCLUSION: Milch osteotomy is an effective procedure for cubitus valgus deformity correction and its associated tardy ulnar nerve palsy without a decrease in elbow ROM. Correction of even severe valgus deformities without concurrent anterior transposition of the ulnar nerve is likely to improve ulnar nerve symptoms.

15.
Malays Orthop J ; 14(2): 151-153, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32983394
16.
Colloids Surf B Biointerfaces ; 196: 111335, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32927339

RESUMO

Silver nanoparticles (AgNPs) exhibit excellent anti-microbial and bactericidal properties. Due to bacterial abhorrence for AgNPs, it is difficult to develop a label-free, sensitive and low-cost bacteria sensor using them. In the present article, we report that an ultrathin and uniform Langmuir-Schaefer (LS) film of AgNPs can be employed for bacteria sensing effectively as compared to that of non-uniform and randomly distributed AgNPs in spin coated film. The uniformly distributed AgNPs in the LS film offer a relatively larger contact surface for bacteria as compared to that of spin coated film. Due to higher contact surface, adsorption of the bacteria on LS film is strongly preferable as compared to that of spin coated film leading to an enhanced sensing performance of the LS film than that of spin coated film. Soil bacteria was grown by the standard protocol and were utilized as model system for bacteria sensing application. The soil bacteria sensing was done by monitoring the piezoresponse and dissipation parameters using a quartz crystal microbalance, simultaneously. Our study indicates that the LS film of AgNPs not only facilitates the adsorption of the soil bacteria but also kills them.


Assuntos
Nanopartículas Metálicas , Prata , Antibacterianos/farmacologia , Bactérias , Escherichia coli
17.
Nanotechnology ; 31(36): 365605, 2020 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-32422619

RESUMO

Triphenylene based discotic liquid crystal (TP) molecules are rich in π-electrons which facilitate π-stacking interaction of the molcules leading to formation of one dimensional nanowires. These nanowires can assemble to form nanoribbons due to a lateral cohesive force among the nanowires. The flat nanoribons undergo a morphological transformation due to incorporation of silver nanoparticles (SNP) into the matrix of TP molecules. The presence of SNP induces a chiral twisting to the nanoribbons and therefore the flat nanoribbons transform into a helical nanoribbon structure. The global chiral structure exhibited by the composition of achiral constituents is due to the creation of topological defects like disclination and dislocation. These defects can lead to a geometrical frustration in the nanoribbons which relaxes with the formation of twisted helical nanoribbons. A minor change in morphology of the supramolecular assembly can have a remarkable effect on the physicochemical properties of the nanoribbons. In this article, we demonstrate that even a minor change in the geometry of aliphatic chains on the surface of nanoribbons can be employed for sensing organic solvents such as acetone and ethanol. The sensing was performed at room temperature. Relative humidity has no effect on the sensing response.

18.
AJNR Am J Neuroradiol ; 41(2): 238-245, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32029467

RESUMO

BACKGROUND AND PURPOSE: Spiral MR imaging has several advantages compared with Cartesian MR imaging that can be leveraged for added clinical value. A multicenter multireader study was designed to compare spiral with standard-of-care Cartesian postcontrast structural brain MR imaging on the basis of relative performance in 10 metrics of image quality, artifact prevalence, and diagnostic benefit. MATERIALS AND METHODS: Seven clinical sites acquired 88 total subjects. For each subject, sites acquired 2 postcontrast MR imaging scans: a spiral 2D T1 spin-echo, and 1 of 4 routine Cartesian 2D T1 spin-echo/TSE scans (fully sampled spin-echo at 3T, 1.5T, partial Fourier, TSE). The spiral acquisition matched the Cartesian scan for scan time, geometry, and contrast. Nine neuroradiologists independently reviewed each subject, with the matching pair of spiral and Cartesian scans compared side-by-side, and scored on 10 image-quality metrics (5-point Likert scale) focused on intracranial assessment. The Wilcoxon signed rank test evaluated relative performance of spiral versus Cartesian, while the Kruskal-Wallis test assessed interprotocol differences. RESULTS: Spiral was superior to Cartesian in 7 of 10 metrics (flow artifact mitigation, SNR, GM/WM contrast, image sharpness, lesion conspicuity, preference for diagnosing abnormal enhancement, and overall intracranial image quality), comparable in 1 of 10 metrics (motion artifacts), and inferior in 2 of 10 metrics (susceptibility artifacts, overall extracranial image quality) related to magnetic susceptibility (P < .05). Interprotocol comparison confirmed relatively higher SNR and GM/WM contrast for partial Fourier and TSE protocol groups, respectively (P < .05). CONCLUSIONS: Spiral 2D T1 spin-echo for routine structural brain MR imaging is feasible in the clinic with conventional scanners and was preferred by neuroradiologists for overall postcontrast intracranial evaluation.


Assuntos
Encéfalo/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos , Neuroimagem/métodos , Adulto , Idoso , Artefatos , Feminino , Humanos , Aumento da Imagem/métodos , Masculino , Pessoa de Meia-Idade
19.
J Nanosci Nanotechnol ; 20(4): 2526-2537, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31492272

RESUMO

The widespread use of miniature electronic devices calls for energy-dense storage strategies. The supercapacitor-based energy storage devices with high areal capacitance are desired energy storage alternative. It is still a challenge to fabricate supercapacitor-based energy devices with consistent performance. The porous metal oxides with large areal capacitance are desired materials for electrode, but there exists a limited understanding of the influence of synthesis parameters on microstructural properties, which largely govern their electrochemical performance. In the present work, hierarchal spinel nickel cobaltite (NiCo2O4) nanostructures were synthesized in the presence of the varying amount of hydrolyzing agent via a simple hydrothermal method coupled with a simple post-annealing process. This work focuses on understanding the influence of hydrolyzing agent in controlling the microstructure and hence ensuing electrochemical properties of the NiCo2O4 based electrode. Based on the urea hydrolyzing content, the as synthesized NiCo2O4 nanostructure varied from the rod, plate to nanoflower. The mesoporous nanostructures, with urea content 1.49 gm, exhibit a sizeable BJH surface area (79.2 m² g-1) and high mesopore volume (0.140 cm³ g-1). Remarkably, the NiCo2O4 nanoflower shows high specific capacitance of 3143.451 F/g at 2 mV/s scan rate, 1264.5 F/g at 1 A/g current density, energy density of 56 Wh/kg and power density of 8,400 W/kg in 3 M KOH electrolyte. The capacitance loss after 5000 cycles is 48% at the current density of 10 A/g, indicating their excellent cycling stability. The impressive electrocatalytic activity is largely ascribed to the high intrinsic electronic conductivity, superior mesoporous nanostructures and rich surface Ni active species of the NiCo2O4 materials, which can largely boost the interfacial electroactive sites and charge transfer rates indicating promising applications as electrodes in future supercapacitors.

20.
J Nanosci Nanotechnol ; 20(5): 3182-3194, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-31635663

RESUMO

Template-assisted facile synthesis of tubular Co3O4 microstructures and its electrochemical performance was studied to understand its use as a potential electrode material for supercapacitors. Tubular porous Co3O4 microstructures were synthesized using cotton fibers as bio-template. The as-obtained templated Co3O4 structure inherits the morphology and microstructure of cotton fiber. The electrochemical performance of the electrode made up of tubular Co3O4 structure was evaluated in 3 M KOH, NaOH, and LiOH aqueous electrolytes. The large-surface-area of tubular Co3O4 microstructure has a noticeable pseudocapacitive performance with a capacitance of 401 F/g at 1 A/g and 828 F/g at 2 mV/s, a Coulombic efficiency averaging ~100%, and excellent cycling stability with capacitance retention of about 80% after 5,000 cycles. Overall, the tubular Co3O4 microstructure displayed superior electrochemical performance in 3 M KOH electrolyte with peak power density reaching 5,500 W/kg and energy density exceeding 22 Wh/kg. The superior performance of tubular Co3O4 microstructure electrode is attributed to its high surface area and adequate pore volume distribution, which allows effective redox reaction and diffusion of hydrated ions. The facile synthesis method can be adapted for preparing various metal oxide microstructures for possible applications in catalysis, electrochemical, sensors, and fuel cells applications.

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