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1.
Braz. j. biol ; 82: e238665, 2022. tab
Artigo em Inglês | LILACS-Express | LILACS | ID: biblio-1153463

RESUMO

Abstract Malakand region is an endemic area for cutaneous leishmaniasis (CL). However, there are limited number of studies of this disease in Pakistan. Therefore, a study was conducted to understand the level of awareness attitude and practice among the residents of Makaland towards CL and the disease vectors. This study adopted a cross-sectional approach with a total of 400 respondents (n=93 rural and n= 307 urban). Overall, the population in Malakand region (61.2%) were well-informed in the role of sand fly in transmitting diseases, but most lack knowledge on the vector's behavior and almost a quarter (24.5%) were unable to provide knowledge on proper control measures. Alarmingly, the practice and attitudes of the general population was not satisfactory as close to half (49.8%) of the population did adopt any control method. This study calls for increase in awareness through health education campaign to reduce the risk of cutaneous leishmaniasis outbreaks in the future.


Resumo A região de Malakand é uma área endêmica para leishmaniose cutânea (CL). No entanto, há um número limitado de estudos sobre esta doença no Paquistão. Portanto, foi realizado um estudo para entender o nível de atitude e prática de conscientização entre os residentes de Makaland em relação aos CL e os vetores da doença. Este estudo adotou uma abordagem transversal com um total de 400 entrevistados (n = 93 rural e n = 307 urbano). No geral, a população da região de Malakand (61,2%) estava bem informada sobre o papel da mosca na transmissão de doenças, mas a maioria não possui conhecimento sobre o comportamento do vetor e quase um quarto (24,5%) foi incapaz de fornecer conhecimento sobre medidas de controle adequadas . De maneira alarmante, a prática e as atitudes da população em geral não foram satisfatórias, pois cerca da metade (49,8%) da população adotou algum método de controle. Este estudo apela ao aumento da conscientização por meio de campanhas de educação em saúde para reduzir o risco de surtos de leishmaniose cutânea no futuro.

2.
Braz J Biol ; 82: e238665, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33825759

RESUMO

Malakand region is an endemic area for cutaneous leishmaniasis (CL). However, there are limited number of studies of this disease in Pakistan. Therefore, a study was conducted to understand the level of awareness attitude and practice among the residents of Makaland towards CL and the disease vectors. This study adopted a cross-sectional approach with a total of 400 respondents (n=93 rural and n= 307 urban). Overall, the population in Malakand region (61.2%) were well-informed in the role of sand fly in transmitting diseases, but most lack knowledge on the vector's behavior and almost a quarter (24.5%) were unable to provide knowledge on proper control measures. Alarmingly, the practice and attitudes of the general population was not satisfactory as close to half (49.8%) of the population did adopt any control method. This study calls for increase in awareness through health education campaign to reduce the risk of cutaneous leishmaniasis outbreaks in the future.


Assuntos
Leishmaniose Cutânea , Psychodidae , Animais , Estudos Transversais , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Leishmaniose Cutânea/epidemiologia , Paquistão/epidemiologia , População Rural , População Urbana
3.
Braz J Biol ; 82: e238665, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33787717

RESUMO

Malakand region is an endemic area for cutaneous leishmaniasis (CL). However, there are limited number of studies of this disease in Pakistan. Therefore, a study was conducted to understand the level of awareness attitude and practice among the residents of Makaland towards CL and the disease vectors. This study adopted a cross-sectional approach with a total of 400 respondents (n=93 rural and n= 307 urban). Overall, the population in Malakand region (61.2%) were well-informed in the role of sand fly in transmitting diseases, but most lack knowledge on the vector's behavior and almost a quarter (24.5%) were unable to provide knowledge on proper control measures. Alarmingly, the practice and attitudes of the general population was not satisfactory as close to half (49.8%) of the population did adopt any control method. This study calls for increase in awareness through health education campaign to reduce the risk of cutaneous leishmaniasis outbreaks in the future.


Assuntos
Leishmaniose Cutânea , Psychodidae , Animais , Estudos Transversais , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Leishmaniose Cutânea/epidemiologia , Paquistão/epidemiologia , População Rural , População Urbana
4.
Surgeon ; 2020 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-33257272

RESUMO

INTRODUCTION: The COVID-19 pandemic has placed a significant strain on healthcare resources and utilisation globally. The appearance of the disease in the Republic of Ireland resulted in a broad postponement of scheduled and routine surgical care. The influence of the novel coronavirus, and the associated imposition of public health measures such as school closures and social distancing, on the burden of emergency surgical disease is less clear. AIM: The aim of this study was to examine the impact of COVID-19 on the number of patients presenting to our institution with emergent surgical illnesses or requiring emergency general surgical procedures. METHODS: All patients attending our service between March 1st 2020 and April 30th 2020 were identified retrospectively by examining electronic handover and electronic discharge summaries, and data were collected relating to demographics, presenting illness, critical care utilisation, length of stay, operative or endoscopic procedure performed, and in-hospital mortality. Similar data were collected March 1st to April 30th 2019, 2018, and 2017 respectively to allow direct comparison. RESULTS: 151 patients were admitted during the study period, compared to a total of 788 during the proceeding three years (mean 2.49 admissions per night versus 4.35 per night, 42.8% reduction, p < 0.001). Median age of admitted patients was 51.8 years, compared to 50.3 years formerly (p = 0.35). 53 emergency procedures were performed, compared to a median of 70 over the same period in the previous years (mean 0.87 per day versus 1.16 per day, 25.4% reduction, p = 0.05). CONCLUSION: A significant overall reduction in the number of patients being admitted to our unit and requiring emergency surgical procedures during March and April 2020 was seen, in line with patterns reported internationally.

5.
J Appl Microbiol ; 2020 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-33174331

RESUMO

AIM: The family Arcobacteraceae formerly genus Arcobacter has recently been reclassified into six genera. Among nine species of the genus Aliarcobacter, Aliarcobacter faecis and Aliarcobacter lanthieri have been identified as emerging pathogens potentially cause health risks to humans and animals. This study was designed to develop/optimize, validate and apply Arcobacteraceae family- and two species-specific (A. faecis and A. lanthieri) loop-mediated isothermal amplification (LAMP) assays to rapidly detect and quantify total number of cells in various environmental niches. METHODS AND RESULTS: Three sets of LAMP primers were designed from conserved and variable regions of 16S rRNA (family-specific) and gyrB (species-specific) genes. Optimized Arcobacteraceae family-specific LAMP assay correctly amplified and detected 24 species, whereas species-specific LAMP assays detected A. faecis and A. lanthieri reference strains as well as 91 pure and mixed culture isolates recovered from aquatic and faecal sources. The specificity of LAMP amplification of A. faecis and A. lanthieri was further confirmed by restriction fragment length polymorphism analysis. Assay sensitivities were tested using variable DNA concentrations extracted from simulated target species cells in an autoclaved agricultural water sample by achieving a minimum detection limit of 10 cells mL-1 (10 fg). Direct DNA-based quantitative detection, from agricultural surface water, identified A. faecis (17%) and A. lanthieri (1%) at a low frequency compared to family-level (93%) with the concentration ranging from 2·1 × 101 to 2·2 × 105 cells 100 mL-1 . CONCLUSIONS: Overall, these three DNA-based rapid and cost-effective novel LAMP assays are sensitive and can be completed in less than 40 min. They have potential for on-site quantitative detection of species of family Arcobacteraceae, A. faecis and A. lanthieri in food, environmental and clinical matrices. SIGNIFICANCE AND IMPACT OF THE STUDY: The newly developed LAMP assays are specific, sensitive, accurate with higher reproducibility that have potential to facilitate in a less equipped lab setting and can help in early quantitative detection and rate of prevalence in environmental niches. The assays can be adopted in the diagnostic labs and epidemiological studies.

6.
Artigo em Inglês | MEDLINE | ID: mdl-33224247

RESUMO

In December, 2019 in Wuhan city of China, a novel coronavirus (SARS-CoV-2) has garnered global attention due to its rapid transmission. World Health Organization (WHO) termed the infection as Coronavirus Disease 2019 (COVID-19) after phylogenic studies with SARS-CoV. The virus causes severe respiratory infections with dry cough, high fever, body ache and fatigue. The virus is primarily transmitted among people through respiratory droplets from COVID-19 infected person. WHO declared this COVID-19 outbreak a pandemic and since February, 2020 affected countries have locked down their cities, industries and restricted the movement of their citizens to minimize the spread of the virus. In spite of the negative aspects of coronavirus on the globe, the coronavirus crises brought a positive impact on the natural environment. Countries where the movement of citizens was seized to stop the spread of coronavirus infection have experienced a noticeable decline in pollution and greenhouse gases emission. Recent research also indicated that this COVID-19-induced lockdown has reduced the environmental pollution drastically worldwide. In this review, we have discussed some important positive impacts of coronavirus on environmental quality by compiling the recently published data from research articles, NASA (National Aeronautics and Space Administration) and ESA (European Space Agency).

7.
Artigo em Inglês | MEDLINE | ID: mdl-33074196

RESUMO

BACKGROUND: Phototherapy is the primary treatment for hyperbilirubinemia in neonates. Hypocalcemia is a lesser known but potential detrimental effect of phototherapy. It has been hypothesized that phototherapy inhibits pineal secretion of melatonin, which blocks the effect of cortisol on bone calcium. Therefore, unchecked cortisol increases bone uptake of calcium and induces hypocalcemia. Covering head during phototherapy in order to prevent light reaching to the pineal gland which eventually leads to the prevention of hypocalcemia is hypothesized to prevent hypocalcemia but it lacks sufficient evidence worldwide. METHOD: It is a prospective, randomized controlled study. 112 neonates were randomized into two groups of 56 neonates. Group A underwent phototherapy without head cover and group B with head covered by a cap. RESULT: The mean decline in serum ionic calcium after 48 hours of phototherapy in group A and group B was 0.57±0.37 mg/dl and 0.34±0.24 mg/dl respectively. This decline in serum ionic calcium was significantly higher in group A. (p <  0.001). 26.8% newborns from group A developed hypocalcemia while in group B only 14.3% developed hypocalcemia however it was not found to be statistically significant. Incidence of symptomatic hypocalcemia between the two groups was also not significant. CONCLUSION: There was significant reduction in serum calcium in neonates undergoing phototherapy without head cover as compared to neonates with head cover but risk of hypocalcemia was not significant. Further studies with larger sample size including preterm are recommended.

8.
Clin Exp Immunol ; 202(1): 93-105, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32580239

RESUMO

Behçet's disease (BD) is a vasculitis of unknown aetiology typified by chronic recurrent oral ulcers and systemic inflammatory manifestations. Neutrophils, and specifically their protease neutrophil elastase (NE), have been implicated in its pathology. Although NE is an effective anti-microbial, excessive NE can damage host tissue. Recurrent oral ulceration is a primary BD symptom, therefore we hypothesized that excessive neutrophil infiltration evidenced by increased NE and a reduction in specific endogenous inhibitors, secretory leucocyte protease inhibitor (SLPI) and alpha1-anti-trypsin (α1AT) contributes to BD mucosal instability. NE, SLPI and α1AT were quantified in saliva from BD patients with active oral ulcers (BDa) and quiet without ulcers (BDq), recurrent aphthous stomatitis (RASa; RASq) and healthy controls (HC). Although BDq saliva had marginally higher median NE levels (1112 ng/ml) compared to both RASq (1043 ng/ml) and HC (999 ng/ml), SLPI was significantly reduced in BDq (P < 0·01). Despite decreased SLPI protein, mRNA expression was significantly increased in BDq buccal epithelial swabs compared to RASq and HC (P < 0·05, P < 0·001). NE remained enzymatically active, although α1AT levels were at least eight times higher than SLPI in all groups, suggesting that α1AT does not have a primary role in counteracting NE in saliva. Furthermore, NE levels in BDa patients medicated with both azathioprine (AZA) and colchicine (COLC) were significantly lower than those on COLC (P = 0·0008) or neither (P = 0·02), indicating that combining AZA + COLC may help to regulate excessive NE during ulceration. This study showed that enzymatically active NE coupled with reduced SLPI in BD saliva may contribute to recurrent oral ulcerations.

9.
J Adv Res ; 24: 463-474, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32566282

RESUMO

Fractional calculus (FC) is widely used in many interdisciplinary branches of science due to its effectiveness in describing and investigating complicated phenomena. In this work, nonlinear dynamics for a new physical model using nonlocal fractional differential operator with singular kernel is introduced. New Routh-Hurwitz stability conditions are derived for the fractional case as the order lies in [0,2). The new and basic Routh-Hurwitz conditions are applied to the commensurate case. The local stability of the incommensurate orders is also discussed. A sufficient condition is used to prove that the solution of the proposed system exists and is unique in a specific region. Conditions for the approximating periodic solution in this model via Hopf bifurcation theory are discussed. Chaotic dynamics are found in the commensurate system for a wide range of fractional orders. The Lyapunov exponents and Lyapunov spectrum of the model are provided. Suppressing chaos in this system is also achieved via two different methods.

10.
Br Dent J ; 228(11): 817-818, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32541720
12.
Sci Rep ; 10(1): 8327, 2020 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-32433475

RESUMO

In current study natural convection flow of second grade fluid in an oscillating infinite vertical cylinder is investigated. The dimensionless governing equations for temperature and velocity are obtained by introducing the non-dimensional variables. Exact solutions for temperature and velocity field are computed by means of integral transformation. Solutions for cosine and sine oscillations of velocity field are introduced in the form of transient and post-transient arrangements. A special case for Newtonian fluid is obtained from general results and transients solutions are computed in terms of tables. In the end, the impact of dimensionless numbers (Grashof and Prandtl numbers) at different values of time is presented in graphical form and found that velocity for Newtonian fluid has greater values than the second grade fluid. Furthermore, there are some comparisons of calculated solutions with existing solutions in literature.

13.
Community Dent Health ; 37(4): 247-252, 2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-32338835

RESUMO

OBJECTIVE: Describe the inequalities in oral health in children treated in a hospital located in a deprived urban area in the UK. RESEARCH DESIGN: Case-note review of 1911 0-17-year-olds who underwent dental extractions under a general anaesthetic (DGA). MAIN OUTCOME MEASURES: Associations between Age, Ethnicity, Year-of-Treatment and Index of Multiple Deprivation (IMD) with the number of teeth extracted. Analysis used multilevel modelling assuming a Poisson distribution. RESULTS: Mean number of teeth extracted was higher in the youngest children treated aged 0-5 years (relative risk coefficient, (RR=exp(ß)=1.39; 95% CI 1.24 to 1.56) compared to those aged 6-17 years and in 'Other Whites' (predominantly immigrants from Eastern Europe) (RR=exp(ß)=1.34; 95% CI 1.25 to 1.43), 'South Asians' (RR=exp(ß)=1.15; 95% CI 1.08 to 1.23) but fewer in the 'Black' ethnic group (RR=exp(ß)=0.85; 95% CI 0.76 to 0.95). DGA increased during the study with more teeth extracted in 2015, 2016 and 2017 (RR=exp(ß)=1.12, 95% CI 1.22, 1.25) and with a negative gradient in the rate of DGA's (per decile) in children from the most deprived to most affluent locations (RR=exp(ß)=0.98; 95% CI 0.97 to 0.99). CONCLUSIONS: Significant oral health inequalities exist in children from a deprived urban area in the UK. A preventive approach to children's oral health is needed to reduce such inequalities, including public health and healthcare agencies to informing parents of children whose first language is not English about dental caries.

15.
Chem Commun (Camb) ; 55(70): 10456-10459, 2019 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-31411211

RESUMO

A bio-orthogonal chemistry-based approach for fluorescent labelling of ribosomal RNA is described. It involves an adenosine analogue modified with trans-cyclooctene and masked 5'-phosphate group using aryl phosphoramidate. The incorporation into rRNA has been confirmed using agarose gel electrophoresis, as well as a highly sensitive UHPLC-MS/MS method. Fluorescent labelling of rRNA has been achieved in live HeLa cells via an inverse electron demand Diels-Alder reaction with a tetrazine conjugated to an Oregon Green fluorophore. This communication describes the stepwise approach that led to the development and characterization of the probe. The results demonstrate a new strategy towards development of future fluorescent probes to investigate the biochemistry of nucleic acids.


Assuntos
Corantes Fluorescentes/química , RNA Ribossômico/química , Cromatografia Líquida de Alta Pressão/métodos , Reação de Cicloadição , Células HeLa , Humanos , Espectrometria de Massas em Tandem/métodos
16.
J Dairy Sci ; 102(11): 10395-10410, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31447151

RESUMO

Neutrophils are the most important polymorphonuclear leukocytes (PMNL), representing the front-line defense involved in pathogen clearance upon invasion. As such, they play a pivotal role in immune and inflammatory responses. Isolated PMNL from 5 mid-lactating Holstein dairy cows were used to evaluate the in vitro effect of methionine (Met) and choline (Chol) supplementation on mRNA expression of genes related to the Met cycle and innate immunity. The target genes are associated with the Met cycle, cell signaling, inflammation, antimicrobial and killing mechanisms, and pathogen recognition. Treatments were allocated in a 3 × 3 factorial arrangement, including 3 Lys-to-Met ratios (L:M, 3.6:1, 2.9:1, or 2.4:1) and 3 levels of supplemental Chol (0, 400, or 800 µg/mL). Three replicates per treatment group were incubated for 2 h at 37°C and 5% atmospheric CO2. Both betaine-homocysteine S-methyltransferase and choline dehydrogenase were undetectable, indicating that PMNL (at least in vitro) cannot generate Met from Chol through the betaine pathway. The PMNL incubated without Chol experienced a specific state of inflammatory mediation [greater interleukin-1ß (IL1B), myeloperoxidase (MPO), IL10, and IL6] and oxidative stress [greater cysteine sulfinic acid decarboxylase (CSAD), cystathionine gamma-lyase (CTH), glutathione reductase (GSR), and glutathione synthase (GSS)]. However, data from the interaction L:M × Chol indicated that this negative state could be overcome by supplementing additional Met. This was reflected in the upregulation of methionine synthase (MTR) and toll-like receptor 2 (TLR2); that is, pathogen detection ability. At the lowest level of supplemental Chol, Met downregulated GSS, GSR, IL1B, and IL6, suggesting it could reduce cellular inflammation and enhance antioxidant status. At 400 µg/mL Chol, supplemental Met upregulated PMNL recognition capacity [higher TLR4 and L-selectin (SELL)]. Overall, enhancing the supply of methyl donors to isolated unstimulated PMNL from mid-lactating dairy cows leads to a low level of PMNL activation and upregulates a cytoprotective mechanism against oxidative stress. Enhancing the supply of Met coupled with adequate Chol levels enhances the gene expression of PMNL pathogen-recognition mechanism. These data suggest that Chol supply to PMNL exposed to low levels of Met effectively downregulated the entire repertoire of innate inflammatory-responsive genes. Thus, Met availability in PMNL during an inflammatory challenge may be sufficient for mounting an appropriate biologic response.


Assuntos
Bovinos/sangue , Colina/administração & dosagem , Metionina/administração & dosagem , Neutrófilos/metabolismo , 5-Metiltetra-Hidrofolato-Homocisteína S-Metiltransferase , Animais , Antioxidantes/metabolismo , Bovinos/imunologia , Bovinos/fisiologia , Colina/genética , Colina/metabolismo , Dieta/veterinária , Regulação para Baixo , Feminino , Expressão Gênica , Imunidade Inata/genética , Inflamação/genética , Inflamação/veterinária , Lactação/efeitos dos fármacos , Metionina/genética , Metionina/metabolismo , Neutrófilos/imunologia , Estresse Oxidativo/genética , RNA Mensageiro/metabolismo
17.
Int J Biometeorol ; 63(10): 1331-1346, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31280374

RESUMO

A supplement which ameliorates temperature-humidity menace in food producing livestock is a prerequisite to develop climate smart agricultural packages. A study was conducted to investigate the heat stress ameliorative efficacy of alpha lipoic acid (ALA) in male Murrah water buffaloes (Bubalus bubalis). Eighteen animals (293.61 ± 4.66Kg Bwt) were randomly allocated into three groups (n = 6); NHSC (non-heat-stressed control), HS (heat-stressed) and HSLA (heat-stressed-supplemented with ALA@32 mg/kg Bwt orally) based on the temperature humidity index (THI) and ALA supplementation. HS and HSLA were exposed to simulated heat challenge in a climatically controlled chamber (40 °C) for 21 consecutive days, 6 h daily. Physiological responses viz. Respiration rate (RR), Pulse rate (PR) and Rectal temperature (RT) were recorded daily before and after heat exposure. Blood samples were collected at the end of heat exposure on days 1, 6, 11, 16, and 21 and on day 28 (7th day post exposure which is considered as recovery) for peripheral blood mononuclear cells (PBMCs) separation, followed by RNA and Protein extraction for Real time quantitative PCR and Western blot analysis respectively, of heat shock proteins (HSPs). Two-way repeated measure ANOVA was performed between groups at different experimental periods. RR (post exposure) in HS and HSLA was significantly higher (P < 0.05) than NHSC from day 1 onwards but HSLA varied significantly from the HS 8th day onwards. Post exposure RT and PR in both HS and HSLA varied (P < 0.05) from NHSC throughout the study; but between HS and HSLA, RT significantly varied on initial 2 days and last 6 days (from days 16 to 21). HSP70 mRNA expression significantly up regulated in high THI groups with respect to the low THI group throughout the experimental period. During chronic stress (days 16 and 21) HSP70 significantly (P < 0.05) increased in HS but not in HSLA (P > 0.05) with respect to NHSC. ALA supplementation up-regulates and sustains (P < 0.05) the expression of HSP90 in HSLA in comparison to the HS and NHSC. HSP105 expression was significantly up-regulated (P < 0.05) in HS on days 16 and 21 (during long-term exposure) but only on day 21 (P < 0.05) in HSLA. HSP70, HSP90, and HSP105 protein expression dynamics were akin to the mRNA transcript data between the study groups. In conclusion, supplementing ALA ameliorates the deleterious effect of heat stress as reflected by improved physiological and cellular responses. ALA supplementation improved cellular antioxidant status and sustained otherwise easily decaying heat shock responses which concertedly hasten the baton change from a limited window of thermo tolerance to long run acclimatization.


Assuntos
Búfalos , Suplementos Nutricionais , Temperatura Alta , Ácido Tióctico , Animais , Umidade , Leucócitos Mononucleares , Masculino , Distribuição Aleatória
18.
Analyst ; 144(11): 3488-3493, 2019 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-30939183

RESUMO

The speciation of highly-diluted elements by X-ray absorption spectroscopy in a diverse range of materials is extremely challenging, especially in biological matrices such as articular cartilage. Here we show that using a high energy resolution fluorescence detected X-ray absorption spectroscopy (HERFD-XAS) technique coupled to an array of crystal analyzers, selenium speciation down to 400 ppb (µg kg-1) within articular cartilage can be demonstrated. This is a major advance in the speciation of highly-diluted elements through X-ray absorption spectroscopy and opens new possibilities to study the metabolic role of selenium and other elements in biological samples.


Assuntos
Cartilagem Articular/química , Selênio/análise , Animais , Bovinos , Fluorescência , Humanos , Análise dos Mínimos Quadrados , Limite de Detecção , Masculino , Análise de Componente Principal , Espectroscopia por Absorção de Raios X/métodos
19.
Artigo em Inglês | MEDLINE | ID: mdl-30743072

RESUMO

Traditional melt-quenching technique is adopted for synthesis of Sm2O3 doped lithium barium gadolinium silicate (LBGS: Li2O-BaO-Gd2O3-SiO2) glasses. These glass samples are characterized by different spectroscopic techniques under ambient conditions. Density and molar volume of the present LBGS glass samples increase with increasing Sm3+ ion-concentration. JO intensity parameters Ωλ (where λ = 2, 4 and 6) are evaluated by using Judd-Ofelt theory and Ω4 > Ω2 > Ω6 trend is observed. Furthermore, these parameters are used to evaluate radiative properties like radiative transition probability, branching ratio, radiative lifetime and stimulated emission cross-section for state 4G5/2 of Sm3+ ion. The measured color coordinates for the title glass fall within orange region of CIE diagram. For the present LBGS glasses, the correlated color temperature values are less than warm. The lifetime for the 4G5/2 decreases from 2.468 to 0.566 ms when concentration increases from 0.1 to 2.0 mol% of Sm3+ ions. The analysis of non-exponential behavior of the decay profile through Inokuti-Hirayama model for S = 6 indicates that the energy transfer between Sm3+ ions is due to dipole-dipole interactions. Further energy transfer parameters (Q), critical distance (Ro, Å) and donor-acceptor interaction parameters (CDA x 10-40 cm6/s) of Sm3+ ions doped LBGS glasses were evaluated and compared to other glasses. From the evaluated results it is suggested that the present novelty of the work emphasizes on new matrix LBGS doped with Sm3+ ions showing increasing energy transfer rate with increasing in concentration of Sm2O3 content indicating these glasses are potential candidate for orange-light emitting device applications.

20.
Artigo em Inglês | MEDLINE | ID: mdl-30428428

RESUMO

Li2O-BaO-Gd2O3-SiO2 glasses with different concentration of Eu3+ ions were developed by the traditional melt quenching technique and characterized via FTIR, absorption, excitation, emission and CIE color coordinates analysis for visible red emission application. The FTIR shows strong band at position 740 cm-1 which is attributed to Si-O-Si symmetric stretching mode. Density and molar volume of LBGSEu glasses increases with Eu3+ ions concentration. The covalent nature of bond between the Eu3+ ions and surrounding ligands was confirmed from the bonding parameter (δ). From absorption spectra JO-parameters and oscillator strength are evaluated for LBGSEu6 glass. From JO-parameters, Eu3+ ions have asymmetric coordination environment and stronger covalency. The phonon line PSB (22,522 cm-1) confirm the phonon energy ≈971 cm-1, that corresponds to the energy of one phonon associated with maximum energy of the vibrational mode couple to Eu3+ ions. Under 275 nm and 393 nm excitation, intense red emission was observed at 613 nm, we observe efficient energy transfer phenomena from Gd3+ → Eu3+ in these glasses. Increasing trend of IR with increasing concentration of Eu2O3 indicates the asymmetric environment around Eu3+ ions in LBGS. Moreover, from JO analysis, LBGS glasses have high capability for red laser device with high lasing power and energy extraction ratio. The fluorescence lifetimes show decreasing trend in lifetime with increasing concentration of Eu2O3 is due to radiative transition. From CIE color coordinate, the CIE color coordinates of LBGSEu6 glass fall in reddish region close to orange region and can be useful for optical display devices.

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