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1.
Immunol Lett ; 262: 7-17, 2023 10.
Artigo em Inglês | MEDLINE | ID: mdl-37634711

RESUMO

This study was designed to characterize mice bone marrow (BM) and bone marrow-derived dendritic cells (BMDC) and to compare the surface markers expression and inflammatory cytokine liberation in response to LPS and Bothrops jararacussu venom (BjV) stimulation. Typical morphology was observed in BM and BMDCs from the 4th up to the 8th day of culture using recombinant mouse GM-CSF and IL-4. A high basal level of MHC-II, CD1d, CD83, CD11c, CD80, and low CD86 was expressed by BM cells. After stimulation with GM-CSF/IL-4 for BMDCs differentiation, the BM cells differentiated into BMDCs presented MHC-II, CD1d, CD83, CD11c, CD86, and CD80 expression on the 4th - 8th day accompanied with high levels of TNF-α liberated. The difference between the surface markers' expression was observed in this time course in which CD1d, CD11c, and CD80 remained in high levels of expression, while MHC-II and CD83 showed moderate expression during the differentiation period. Also, cytokines liberation was monitored over the period of the BMDCs culture, and on the 6th day, low levels of IL-6 and IL-1ß were found, while high levels of TNF-α on the 4th and 8th days, both of which contributed to the maturity of the BMDCs. Maturation of DCs with LPS showed significant upregulation of surface markers (MHC-II, CD1d, CD83, CD86, CD80) and pro-inflammatory cytokines (IL-1ß, IL-6, TNF-α) liberation. On the other hand, BjV induced a decrease in CD1d, CD11c, CD83, and CD86 expression in mature BMDCs which was not observed when LPS was used to stimulate BMDCs which probably induces impairment in T-cell activation.


Assuntos
Fator Estimulador de Colônias de Granulócitos e Macrófagos , Fator de Necrose Tumoral alfa , Animais , Camundongos , Fator Estimulador de Colônias de Granulócitos e Macrófagos/farmacologia , Medula Óssea , Interleucina-4 , Interleucina-6 , Lipopolissacarídeos , Venenos de Serpentes , Citocinas , Células Dendríticas
6.
J Hosp Infect ; 105(1): 24-34, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32151673

RESUMO

BACKGROUND: Quality improvement (QI) methods are recommended to address healthcare-associated infections (HCAIs) in hospitals, but whereas internal initiatives have been widely studied, there is little evidence on the application and effect of a QI approach from an external system-wide perspective. AIM: To analyse the effect of a national system-wide QI initiative aimed at promoting HCAI prevention via regulatory interventions in Brazil. METHODS: A QI cycle approach designed and assessed with a before-and-after quasi-experimental design was implemented by the Brazilian Health Regulatory Agency (ANVISA), targeting 1869 hospitals. Eleven evidence-based quality indicators related to HCAI prevention and a composite measure were assembled, shared, and assessed; the intervention to improve was then based on participatory multifaceted regulatory actions. Absolute and relative improvements were estimated after the intervention. FINDINGS: In all, 563 hospitals (30.1% response) totalling 86,837 beds participated in the baseline assessment, and 681 hospitals (36.4% response) totalling 101,231 beds in the second. Ten of the 11 criteria improved (P < 0.05), as well as the composite indicator (P = 0.001) in all the regions of the country, particularly in the group of hospitals participating at baseline. 'Hand hygiene (HH) infrastructure' reached 100% (baseline: 97.9; P = 0.001), 'HH protocol' 96.9% (baseline: 92.9; P = 0.001), 'HH monitoring' 70% (baseline: 60.7; P < 0.001) and 'existence of antimicrobial prescription protocol' 80.7% (baseline: 73.2; P < 0.001), among others. The HCAI rates of the participating hospitals decreased after the intervention (P < 0.05). CONCLUSION: The QI cycle approach was useful in guiding system-wide interventions for patient safety. External regulation was feasible and effective in promoting internal HCAI prevention nationwide.


Assuntos
Infecção Hospitalar/prevenção & controle , Implementação de Plano de Saúde , Hospitais/estatística & dados numéricos , Controle de Infecções/métodos , Brasil , Humanos , Controle de Infecções/organização & administração , Programas Nacionais de Saúde , Segurança do Paciente , Melhoria de Qualidade
7.
J Med Entomol ; 54(2): 485-488, 2017 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-28011729

RESUMO

Culex (Melanoconion) pedroiSirivanakarn & Belkin 1980 and Culex (Melanoconion) ribeirensisForattini & Sallum 1985 are two morphologically very similar species of the Pedroi subgroup of mosquitoes in the Spissipes section of the subgenus Melanoconion of the genus Culex L. 1758. We carried out an analysis of the mitochondrial cytochrome c oxidase I (COI) DNA variation between these two species. The recent observation of sympatric coexistence in a forested area of Rio de Janeiro State (Brazil) triggered the need to validate these two species previously identified based on morphology. We concluded that the COI is a useful tool for identification of Cx. pedroi and Cx. ribeirensis.


Assuntos
Culex/classificação , Complexo IV da Cadeia de Transporte de Elétrons/genética , Proteínas de Insetos/genética , Mitocôndrias/genética , Animais , Brasil , Culex/enzimologia , Culex/genética , DNA Mitocondrial/genética , Variação Genética , Mitocôndrias/enzimologia
8.
Braz J Biol ; 75(4 Suppl 1): S192-5, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26602339

RESUMO

Morphological features that remained uncertain in previous identification keys and descriptions of Sabethes fabricii were evaluated based on species type material and two recently collected males. As a result, the following features of Sa. fabricii should be considered: proboscis with a white ventral spot beyond the middle and variably enlarged to the apex, possibly spatulate in males; setae over root of wing yellowish and may be occasionally brownish, mainly in their basal portion; and proctiger ending in four teeth. Additionally, the first record of bamboo as a natural breeding site for Sa. fabricii as well as the first register of this species in the state of Minas Gerais, Brazil are reported here.


Assuntos
Distribuição Animal , Culicidae/anatomia & histologia , Culicidae/fisiologia , Animais , Brasil , Culicidae/classificação , Ecossistema , Feminino , Masculino
9.
Braz. j. biol ; 75(4)Nov. 2015.
Artigo em Inglês | LILACS-Express | LILACS, VETINDEX | ID: biblio-1468339

RESUMO

Abstract Morphological features that remained uncertain in previous identification keys and descriptions of Sabethes fabricii were evaluated based on species type material and two recently collected males. As a result, the following features of Sa. fabricii should be considered: proboscis with a white ventral spot beyond the middle and variably enlarged to the apex, possibly spatulate in males; setae over root of wing yellowish and may be occasionally brownish, mainly in their basal portion; and proctiger ending in four teeth. Additionally, the first record of bamboo as a natural breeding site for Sa. fabricii as well as the first register of this species in the state of Minas Gerais, Brazil are reported here.


Resumo Caracteres morfológicos que permaneceram incertos em chaves para identificação anteriores e descrições de Sabethes fabricii, foram avaliados com base em material tipo e dois machos recentemente coletados. Como resultado, os seguintes caracteres de Sa. fabricii devem ser considerados: probóscide variavelmente alargada para o ápice, possivelmente espatulada em machos e com uma mancha branca ventral localizada além do seu ponto médio; cerdas sobre a raiz das asas amareladas, podendo ser ocasionalmente marrons, principalmente na sua porção basal, e proctiger com quatro dentes na porção terminal. Adicionalmente, registram-se pela primeira vez, o Bambu como um criadouro natural para Sa. fabricii, bem como a presença dessa espécie para o estado de Minas Gerais, Brasil.

10.
Braz. j. biol ; 75(4,supl.1): 192-195, Nov. 2015. graf
Artigo em Inglês | LILACS | ID: lil-768223

RESUMO

Abstract Morphological features that remained uncertain in previous identification keys and descriptions of Sabethes fabricii were evaluated based on species type material and two recently collected males. As a result, the following features of Sa. fabricii should be considered: proboscis with a white ventral spot beyond the middle and variably enlarged to the apex, possibly spatulate in males; setae over root of wing yellowish and may be occasionally brownish, mainly in their basal portion; and proctiger ending in four teeth. Additionally, the first record of bamboo as a natural breeding site for Sa. fabricii as well as the first register of this species in the state of Minas Gerais, Brazil are reported here.


Resumo Caracteres morfológicos que permaneceram incertos em chaves para identificação anteriores e descrições de Sabethes fabricii, foram avaliados com base em material tipo e dois machos recentemente coletados. Como resultado, os seguintes caracteres de Sa. fabricii devem ser considerados: probóscide variavelmente alargada para o ápice, possivelmente espatulada em machos e com uma mancha branca ventral localizada além do seu ponto médio; cerdas sobre a raiz das asas amareladas, podendo ser ocasionalmente marrons, principalmente na sua porção basal, e proctiger com quatro dentes na porção terminal. Adicionalmente, registram-se pela primeira vez, o Bambu como um criadouro natural para Sa. fabricii, bem como a presença dessa espécie para o estado de Minas Gerais, Brasil.


Assuntos
Animais , Feminino , Masculino , Distribuição Animal , Culicidae/anatomia & histologia , Culicidae/fisiologia , Brasil , Culicidae/classificação , Ecossistema
11.
Braz J Biol ; 75(1): 144-51, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25945631

RESUMO

Alterations in aquatic systems and changes in water levels, whether due to rains or dam-mediated control can cause changes in community structure, forcing the community to readjust to the new environment. This study tested the hypothesis that there is an increase in the richness and abundance of aquatic insects during the rainy season in the Serra da Mesa Reservoir, with the premise that increasing the reservoir level provides greater external material input and habitat diversity, and, therefore, conditions that promote colonization by more species. We used the paired t test to test the differences in richness, beta diversity, and abundance, and a Non-metric Multidimensional Scaling (NMDS) was performed to identify patterns in the community under study. Additionally, Pearson correlations were analyzed between the richness, abundance, and beta diversity and the level of the reservoir. We collected 35,028 aquatic insect larvae (9,513 in dry period and 25,515 in the rainy season), predominantly of the Chironomidae family, followed by orders Ephemeroptera, Trichoptera, and Odonata. Among the 33 families collected, only 12 occurred in the dry season, while all occurred in the rainy season. These families are common in lentic environments, and the dominance of Chironomidae was associated with its fast colonization, their behavior of living at high densities and the great tolerance to low levels of oxygen in the environment. The hypothesis was confirmed, as the richness, beta diversity, and abundance were positively affected by the increase in water levels due to the rainy season, which most likely led to greater external material input, greater heterogeneity of habitat, and better conditions for colonization by several families.


Assuntos
Biodiversidade , Insetos/classificação , Animais , Brasil , Água Doce , Densidade Demográfica , Estações do Ano , Clima Tropical
12.
Braz J Biol ; 74(4): 861-9, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25627596

RESUMO

Tributaries may serve as richness source for the river main channel and the zoobenthos community is a good tool to verify this kind of pattern. In this study, we aimed to characterize the benthic invertebrate assemblage in three tributaries associated to the Paraná River main channel, focusing in Oligochaeta community. We hypothesized that (i) in tributaries, Oligochaeta are richer than the main river (Paraná River) and (ii) dammed tributary (Paranapanema River) is poorly diverse than the others. Samples were conducted in Paranapanema, Baía and Ivinhema tributaries using a modified Petersen grab along three transects (samples conducted inside the tributary, in the mouth of each tributary and inside Paraná River). To analyze (i) the difference between the richness and density among the tributaries and the Paraná River and (ii) effect of each tributary transect on the Oligochaeta richness we used a nonparametric Kruskal-Wallis test. Changes in environmental variables and in richness and composition of Oligochaeta were summarized by Canonic Correspondence Analysis. It was registered 21 different benthic invertebrates taxa, being Oligochaeta assemblage with the highest density. Within Oligochaeta, Narapa bonettoi was the most abundant species, followed by Haplotaxis aedochaeta and Paranadrilus descolei. In our results we refused both hypotheses, because we did not found significant differences for richness and density between the tributaries and the main river, and also no difference between the three transects of each tributary were found. However, the tributaries less influenced by damming, especially the Baía recorded high richness. This corroborates their importance to diversity in the floodplain and the species of Oligochaeta reflect the peculiar characteristics of habitats within each tributaries.


Assuntos
Biodiversidade , Oligoquetos/classificação , Animais , Brasil , Oligoquetos/fisiologia , Densidade Demográfica , Dinâmica Populacional , Rios , Estações do Ano , Movimentos da Água
13.
Mol Genet Genomic Med ; 1(3): 142-154, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24073418

RESUMO

To date, only one genome-wide study has assessed the contribution of CNVs to Parkinson's Disease (PD). We conducted a genome-wide scan for CNVs in a case-control dataset of Ashkenazi Jewish (AJ) origin (268 PD cases and 178 controls). Using high-confidence CNVs, we examined the global genome wide burden of large (≥100Kb) and rare (≤1% in the dataset) CNVs between cases and controls. A total of 986 such CNVs were observed in our dataset of 432 subjects. Overall global burden analyses did not reveal significant differences between cases and controls in CNV rate, distribution of deletions or duplications or number of genes affected by CNVs. Overall deletions (total CNV size and >2x frequency) were found 1.4 times more often in cases than in controls (p=0.019). The large CNVs (>500kb) were also significantly associated with PD (p=0.046, 1.24-folder higher in cases than in controls). Global burden was elevated for rare CNV regions. Specifically, for OVOS2 on Chr12p11.21, CNVs were observed only in PD cases (n=7) but not in controls (p=0.028) and this was experimentally validated. A total of 81 PD cases carried a rare genic CNV that was absent in controls. Ingenuity pathway analysis (IPA) identified ATXN3, FBXW7, CHCHD3, HSF1, KLC1 and MBD3 in the same disease pathway with known PD genes.

14.
Rev. mex. enferm. cardiol ; 20(1): 7-11, ene-abr.2012. graf
Artigo em Espanhol | LILACS, BDENF - Enfermagem | ID: biblio-1035437

RESUMO

Introducción: La alianza mundial para la seguridad del paciente estableció medidas clave para reducir el número de eventos adversos que sufren los pacientes al recibir atención médica, entre ellos se encuentran las caídas, que se definen como cualquier acontecimiento que precipita al paciente al suelo en contra de su voluntad. Objetivo: Identificar los factores que influyen en las caídas de pacientes hospitalizados. Material y métodos: Estudio descriptivo, retrospectivo y transversal de enero a diciembre de 2008; se incluyeron los casos de pacientes hospitalizados que sufrieron caídas. Se elaboró un instrumento para recolectar datos de la base informática del Departamento de Calidad del Cuidado y del expediente clínico de los pacientes quienes sufrieron caída. Variables: edad, sexo, estado neurológico, acompañamiento, riesgo de caída, medidas de seguridad, sitio donde se originó la caída, presencia de lesiones. Resultados: Ingresaron 5,753 pacientes, de los cuales 39 presentaron caída durante su estancia hospitalaria; el 72% fue mayor de 50 años, predominó el sexo femenino con 56%; 31% correspondió a caída del Reposet; 100% de los pacientes estaban en estado de alerta y 74% se encontraban solos. El 92% tenía riesgo de caída alto. Conclusiones: El estudio identificó como factores para caída, la permanencia en el Reposet del paciente mayor de 50 años, con una valoración del riesgo de caída alto. Estos datos demuestran que existen áreas de oportunidad para la valoración, comunicación y vigilancia al paciente hospitalizado, por tal motivo es necesario enfatizar la manera correcta de llevar a cabo el estándar de prevención de caídas.


Introduction: The world alliance for patient safety established measurements to reduce the number of adverse events that patients suffer when in medical attention, among them there are the falls that are defined as any event which sends the patient to the floor against his will. Objective: Identify the factors that influence the falls in the hospitalized patient. Material and methods: A descriptive, transversal and retrospective study from January to December 2008; there were included 7 cases of hospitalized patients who suffer falls. An instrument to collect data from the base of the Health care Quality Department and from the patients’ files that suffer falls was created. Variables: Age, sex, neurologic status, accompaniment, risk of falling, security measurements, place of falling, lesions. Results: 5, 753 patients were admitted, 39 of them fell while in the hospital; 72% was older than 50 years, 56% were male; 31% fell from a recliner; 100% were in alertness, and 74% were alone. The 92% had a high risk of falling. Conclusions: The study identify as factors of falling the staying on the recliner from patients older than 50, assed with a high risk of falling. These data show that there are opportunity areas for the assessment, communication, monitoring, because of this is necessary to emphasize the correct way to carry out the prevention standard for fallings.


Assuntos
Humanos , Acidentes por Quedas/estatística & dados numéricos , Fatores de Risco , Cuidados Médicos
15.
Neurology ; 78(18): 1434-40, 2012 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-22442429

RESUMO

OBJECTIVE: To assess the cognitive phenotype of glucocerebrosidase (GBA) mutation carriers with early-onset Parkinson disease (PD). METHODS: We administered a neuropsychological battery and the University of Pennsylvania Smell Identification Test (UPSIT) to participants in the CORE-PD study who were tested for mutations in PARKIN, LRRK2, and GBA. Participants included 33 GBA mutation carriers and 60 noncarriers of any genetic mutation. Primary analyses were performed on 26 GBA heterozygous mutation carriers without additional mutations and 39 age- and PD duration-matched noncarriers. Five cognitive domains, psychomotor speed, attention, memory, visuospatial function, and executive function, were created from transformed z scores of individual neuropsychological tests. Clinical diagnoses (normal, mild cognitive impairment [MCI], dementia) were assigned blind to genotype based on neuropsychological performance and functional impairment as assessed by the Clinical Dementia Rating (CDR) score. The association between GBA mutation status and neuropsychological performance, CDR, and clinical diagnoses was assessed. RESULTS: Demographics, UPSIT, and Unified Parkinson's Disease Rating Scale-III performance did not differ between GBA carriers and noncarriers. GBA mutation carriers performed more poorly than noncarriers on the Mini-Mental State Examination (p = 0.035), and on the memory (p = 0.017) and visuospatial (p = 0.028) domains. The most prominent differences were observed in nonverbal memory performance (p < 0.001). Carriers were more likely to receive scores of 0.5 or higher on the CDR (p < 0.001), and a clinical diagnosis of either MCI or dementia (p = 0.004). CONCLUSION: GBA mutation status may be an independent risk factor for cognitive impairment in patients with PD.


Assuntos
Disfunção Cognitiva/genética , Análise Mutacional de DNA , Triagem de Portadores Genéticos , Glucosilceramidase/genética , Testes Neuropsicológicos , Doença de Parkinson/genética , Adulto , Doenças dos Gânglios da Base/diagnóstico , Doenças dos Gânglios da Base/genética , Disfunção Cognitiva/diagnóstico , Demência/diagnóstico , Demência/genética , Transtorno Depressivo/diagnóstico , Transtorno Depressivo/genética , Feminino , Testes Genéticos , Genótipo , Humanos , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina , Masculino , Transtornos da Memória/diagnóstico , Transtornos da Memória/genética , Entrevista Psiquiátrica Padronizada , Pessoa de Meia-Idade , Transtornos do Olfato/diagnóstico , Transtornos do Olfato/genética , Doença de Parkinson/diagnóstico , Fenótipo , Proteínas Serina-Treonina Quinases/genética , Ubiquitina-Proteína Ligases/genética , beta-Glucosidase/genética
16.
Artigo em Chinês | WPRIM (Pacífico Ocidental) | ID: wpr-672051

RESUMO

The purpose of this work was to introduce a new concept of coated pellets containing chitosan microspheres loaded with didadosine for oral administration,aiming at reducing the frequency of administration and improving the bioavailability by a suitable release profile.Chitosan microspheres were produced under fluidized bed,followed by extrusion and spheronization to obtain pellets with a mean diameter of about 1 mm.The pellets were then coated with Kollidon(R) VA64 and Kollicoat(R) MAE100P in water dispersion to depict a sustained release profile.Conventional hard gelatine capsules were loaded with these pellets and tested in vitro for their release profile of didadosine.Dissolution testing confirmed that chitosan microsphere pellets provides appropriate sustained release up to 2 h behavior for didanosine.

17.
Parkinsonism Relat Disord ; 17(10): 740-4, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21856206

RESUMO

BACKGROUND: Mutations in parkin are a known genetic risk factor for early onset Parkinson's disease (EOPD) but their role in non-motor manifestations is not well established. Genetic factors for depression are similarly not well characterized. We investigate the role of parkin mutations in depression among those with EOPD and their relatives. METHODS: We collected psychiatric information using the Patient Health Questionnaire and Beck Depression Inventory II on 328 genotyped individuals including 88 probands with early onset PD (41 with parkin mutations, 47 without) and 240 first and second-degree relatives without PD. RESULTS: Genotype was not associated with depression risk among probands. Among unaffected relatives of EOPD cases, only compound heterozygotes (n = 4), and not heterozygotes, had significantly increased risk of depressed mood (OR = 14.1; 95% CI 1.2-163.4), moderate to severe depression (OR = 17.8; 95% CI 1.0-332.0), depression (score ≥ 15) on the Beck Depression Inventory II (BDI-II) (OR = 51.9; 95% CI 4.1-657.4), and BDI-II total depression score (ß = 8.4; 95% CI 2.4-11.3) compared to those without parkin mutations. CONCLUSIONS: Relatives of EOPD cases with compound heterozygous mutations and without diagnosed PD may have a higher risk of depression compared to relatives without parkin mutations. These findings support evidence of a genetic contribution to depression and may extend the phenotypic spectrum of parkin mutations to include non-motor manifestations that precede the development of PD.


Assuntos
Depressão/genética , Predisposição Genética para Doença/genética , Doença de Parkinson/genética , Doença de Parkinson/psicologia , Ubiquitina-Proteína Ligases/genética , Adulto , Idade de Início , Análise Mutacional de DNA , Feminino , Genótipo , Heterozigoto , Humanos , Masculino , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase Multiplex , Mutação , Testes Neuropsicológicos , Fenótipo , Fatores de Risco
18.
Neurology ; 76(4): 319-26, 2011 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-21205674

RESUMO

BACKGROUND: While Parkinson disease (PD) is consistently associated with impaired olfaction, one study reported better olfaction among Parkin mutation carriers than noncarriers. Whether olfaction differs between Parkin mutation heterozygotes and carriers of 2 Parkin mutations (compound heterozygotes) is unknown. OBJECTIVE: To assess the relationship between Parkin genotype and olfaction in PD probands and their unaffected relatives. METHODS: We administered the University of Pennsylvania Smell Identification Test (UPSIT) to 44 probands in the Consortium on Risk for Early-Onset Parkinson Disease study with PD onset ≤50 years (10 Parkin mutation heterozygotes, 9 compound heterozygotes, 25 noncarriers) and 80 of their family members (18 heterozygotes, 2 compound heterozygotes, 60 noncarriers). In the probands, linear regression was used to assess the association between UPSIT score (outcome) and Parkin genotype (predictor), adjusting for covariates. Among family members without PD, we compared UPSIT performance in heterozygotes vs noncarriers using generalized estimating equations, adjusting for family membership, age, gender, and smoking. RESULTS: Among probands with PD, compound heterozygotes had higher UPSIT scores (31.9) than heterozygotes (20.1) or noncarriers (19.9) (p < 0.001). These differences persisted after adjustment for age, gender, disease duration, and smoking. Among relatives without PD, UPSIT performance was similar in heterozygotes (32.5) vs noncarriers (32.4), and better than in heterozygotes with PD (p = 0.001). CONCLUSION: Olfaction is significantly reduced among Parkin mutation heterozygotes with PD but not among their heterozygous relatives without PD. Compound heterozygotes with PD have olfaction within the normal range. Further research is required to assess whether these findings reflect different neuropathology in Parkin mutation heterozygotes and compound heterozygotes.


Assuntos
Doença de Parkinson/genética , Olfato , Ubiquitina-Proteína Ligases/genética , Adulto , Feminino , Heterozigoto , Humanos , Masculino , Pessoa de Meia-Idade , Mutação , Doença de Parkinson/fisiopatologia
19.
Appl Radiat Isot ; 69(8): 1159-61, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21190863

RESUMO

In commercial reactors where a 'pellet missing surface' is observed a cladding crack has also been observed several times. Chips are produced mainly by dynamic impacts during pellet production process as a whole, i.e. emptying the sintering boats, pellets handling, vibration in the bowl feeder and grinding. At this work UO(2) chipping behavior was investigated and showed that pellets with higher density resist more to impacts and also that at the lowest impact angle tested the pellet weight loss was quite high.


Assuntos
Cerâmica/análise , Teste de Materiais , Estresse Mecânico , Compostos de Urânio/análise , Força Compressiva , Porosidade , Propriedades de Superfície , Vibração
20.
Appl Radiat Isot ; 69(8): 1162-4, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21075001

RESUMO

Powder flowability characteristics are often intentionally modified in order to improve their production process. The UO(2) pellet manufacturing process can consist of many steps, e.g. milling, granulation, homogenization, die filling for pressing, etc. By the addition of flow additives, lubricants or glidants the desired workability can be achieved. Temperature also influences the powder processability, leading to an easier or more complex powder flow. The work aims to determine some flowability characteristics for UO(2) powder at different temperatures.


Assuntos
Lubrificantes/química , Compostos de Urânio/análise , Compostos de Urânio/química , Tamanho da Partícula , Pós , Ácidos Esteáricos/química , Propriedades de Superfície , Temperatura
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