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1.
Pediatr Allergy Immunol ; 32(1): 77-85, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-32786104

RESUMO

BACKGROUND: Currently, there are no reliable clinical tools available for predicting asthma in pre-school-aged children with recurrent wheezing. The aim of this study was to evaluate the usefulness of serum periostin, YKL-40, and osteopontin biomarkers in wheezy pre-school-aged children for predicting the development of asthma in school ages. METHODS: The study was prospectively conducted between 2011 and 2017. The clinical features of the pre-school-aged children with recurrent wheezing and the levels of serum periostin, YKL-40, and osteopontin were measured. The same participants were reevaluated in school-age period, and participants with asthma were identified. Relative risk (RR) for the development of asthma was analyzed. RESULTS: Of the 197 pre-school-aged children with recurrent wheezing who were reevaluated in school-age years, 32% of them had asthma. Serum periostin, YKL-40, and osteopontin levels at admission could not predict participants who would have asthma symptoms in school-age years. The RR for continuing of asthma symptoms was higher in participants who had their first wheezing episode before 1 year of age, preterm birth, cesarean section delivery, prenatal smoking exposure, multi-trigger wheezing, parental asthma, modified asthma predictive index positivity, prophylactic vitamin D intake ≤ 12 months, breastfeeding time ≤ 12 month, and aeroallergen sensitivity [RR (95% CI) and P value: 2.813 (1.299-6.091), 0.002; 1.972 (1.274-3.052), 0.009; 1.929 (1.195-3.114), 0.004; 2.232 (1.463-3.406), <0.001; 3.152 (1.949-5.097), <0.001; 1.730 (1.144-2.615), 0.016; 2.427 (1.559-3.777), <0.001; 2.955 (1.558-5.604), <0.001; 1.767 (1.084-2.881), 0.016; 0.765 (0.556-1.053), 0.016; respectively]. CONCLUSION: Results have shown that clinical features were more valuable than biomarkers in predicting having asthma in school-age years in participants who had recurrent wheezing in pre-school-age period.


Assuntos
Asma , Nascimento Prematuro , Asma/diagnóstico , Asma/epidemiologia , Moléculas de Adesão Celular , Cesárea , Criança , Pré-Escolar , Proteína 1 Semelhante à Quitinase-3 , Feminino , Humanos , Lactente , Recém-Nascido , Osteopontina , Gravidez , Sons Respiratórios , Fatores de Risco
2.
Acta Endocrinol (Buchar) ; 17(4): 455-461, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-35747869

RESUMO

Context: Papillary thyroid carcinoma(PTC)s are the indolent progressive tumours. Survivin is a unique bifunctional protein with cell cycle regulation and apoptosis inhibition. The expression of this protein has been shown to be increased in thyroid tumours correlated with aggressive behavior from well differentiated to anaplastic. Objective: In this study, we aimed to investigate the relationship between immunohistochemically survivin expression and tumour-associated prognostic factors in papillary thyroid carcinomas. Design: In patients with thyroidectomy, we compared the clinicopathological findings and immunohistochemical positivity for survivin. Subjects and Methods: In 109 patients, sex, age, tumour size, histological tumour variant, tumour focality, tumour border pattern, tumour peripheral/intratumoural lymphocytic and stromal response, intraglandular spread, extrathyroideal spread, lymph node metastases, lymphocytic tiroiditis and relationships of these findings with survivin positivity were investigated. Results: When we indicated the tumour size and compared it with survivin expression, tumour size correlates with, survivin expression (p = 0.016). Survivin expression was correlated statistically significant with lymphovascular invasion, without stromal response and with intraglandular extension respectively (p<0.001, p = 0.043, p<0.001). No significant correlation was found between other clinicopathological parameters and survival. Conclusion: Few studies have investigated the relationship of survivin expression with prognosis in thyroid papillary carcinomas and showed that survivin was a poor prognostic marker. If its expression is detected in preoperative cytology smears, it may affects the surgical treatment strategy. When it is detected in the tissue, postoperative radioactive iodine treatment plan may be modified and the need for more aggressive follow-up may be considered.

3.
J Pediatr Gastroenterol Nutr ; 70(5): 574-579, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32044836

RESUMO

OBJECTIVE: Continued progress in our understanding of the food protein-induced allergic proctocolitis (FPIAP) will provide the development of diagnostic tests and treatments. We aimed to identify precisely the clinical features and natural course of the disease in a large group of patients. Also, we investigated the predicting risk factors for persistent course since influencing parameters has not yet been established. METHODS: Infants who were admitted with rectal bleeding and had a diagnosis of food protein-induced allergic proctocolitis in 5 different allergy or gastroenterology outpatient clinics were enrolled. Clinical features, laboratory tests, and prognosis were evaluated. Risk factors for persistent course were determined by logistic regression analyses. RESULTS: Among the 257 infants, 50.2% (n = 129) were girls and cow's milk (99.2%) was the most common trigger. Twenty-four percent of the patients had multiple food allergies and had more common antibiotic use (41.9% vs 11.8%), atopic dermatitis (21% vs 10.2%), wheezing (11.3% vs 1.5%), colic (33.8% vs 11.2%), and IgE sensitization (50% vs 13.5%) compared to the single-food allergic group (P < 0.001, P = 0.025, P = 0.003, P < 0.001, respectively). In multivariate logistic regression analysis, presence of colic (odds ratio [OR]: 5.128, 95% confidence interval [CI]: 1.926-13.655, P = 0.001), IgE sensitization (OR: 3.964, 95% CI: 1.424-11.034, P = 0.008), and having allergy to multiple foods (OR: 3.679, 95% CI: 1.278-10.593, P = 0.001] were found to be risk factors for continuing disease after 1 year of age. CONCLUSION: Although most children achieve tolerance at 1 year of age, IgE sensitization, allergy to multiple foods, and presence of colic were risk factors for persistent course and late tolerance. In this context, these children may require more close and extended follow-up.


Assuntos
Hipersensibilidade Alimentar , Hipersensibilidade a Leite , Proctocolite , Alérgenos , Animais , Bovinos , Criança , Feminino , Hipersensibilidade Alimentar/complicações , Hipersensibilidade Alimentar/diagnóstico , Hipersensibilidade Alimentar/epidemiologia , Humanos , Tolerância Imunológica , Lactente , Masculino , Hipersensibilidade a Leite/complicações , Hipersensibilidade a Leite/diagnóstico , Hipersensibilidade a Leite/epidemiologia , Proctocolite/diagnóstico , Proctocolite/etiologia , Fatores de Risco
4.
Luminescence ; 32(5): 786-790, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27958667

RESUMO

In this study, the thermoluminescence (TL) characteristics of Ag-doped and undoped lithium tetraborate (Li2 B4 O7 , LTB) materials, grown using the Czochralski method, were reported. The TL properties of LTB:Ag, such as glow curve structure, dose response, fading and reproducibility, were investigated. The glow curve of the Li2 B4 O7 :Ag single crystal consists of four peaks located at approximately 75, 130, 190 and 275°C; in undoped LTB, the single crystal shows a broad glow curve with peaks at 65, 90, 125, 160 and 190°C using a heating rate of 5°C/s in the 50-350°C temperature region. The high temperature peak of Ag-doped sample at 275°C has a nonlinear dose response within the range from 33 mGy to 9 Gy. There is a linear response in the range of 33-800 mGy; after which, a sublinear region appears up to 9 Gy for Ag-doped LTB single crystal. For undoped single crystal, the dose response is supralinear for low doses and linear for the region between 1 and 9 Gy. The thermal fading ratio of the undoped material is almost 60% for the high temperature peak after 7 days. Ag-doped LTB single crystal exhibits different behaviour over a period of 7 days.


Assuntos
Boratos/química , Medições Luminescentes/métodos , Prata/química , Dosimetria Termoluminescente/métodos , Cristalização , Reprodutibilidade dos Testes , Temperatura
5.
Pediatr Allergy Immunol ; 27(1): 50-4, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26619970

RESUMO

BACKGROUND: Skin testing has a limited role in the diagnosis of non-immediate beta-lactam hypersensitivity in children. The aim of this study was to report the results of oral provocation tests performed without skin tests in children with non-immediate mild cutaneous reactions without systemic symptoms caused by beta-lactam antibiotics. METHODS: Oral provocation tests with suspected antibiotics were performed to patients with non-immediate mild cutaneous reactions without systemic symptoms caused by beta-lactam antibiotics. Skin tests were not performed before provocation tests. A total of five doses were administered with half-an-hour intervals in increasing doses. Provocation was continued for 5 days. RESULTS: A total of 119 patients with a median age of 4.3 (IQR: 2-7.5) years, of whom 58% were males, were included in the study. Amoxicillin-clavulanic acid was the most frequently responsible agent in 87 (73.1%) patients, and most common type of rash was maculopapular in 74 (62.2%) patients. Four patients (3.4%) had an urticarial reaction during the provocation test. CONCLUSION: We did not experience any severe reactions during oral provocation test without previous skin tests performed to children with non-immediate mild cutaneous reactions without systemic symptoms. Omitting skin tests before oral provocation test in this group of children can help decreasing the burden of allergy clinics and alleviating the discomfort of children.


Assuntos
Antibacterianos/administração & dosagem , Antibacterianos/efeitos adversos , Toxidermias/diagnóstico , Hipersensibilidade Tardia/diagnóstico , Testes Imunológicos , Pele/efeitos dos fármacos , beta-Lactamas/administração & dosagem , beta-Lactamas/efeitos adversos , Administração Oral , Criança , Pré-Escolar , Toxidermias/imunologia , Toxidermias/patologia , Feminino , Humanos , Hipersensibilidade Tardia/induzido quimicamente , Hipersensibilidade Tardia/imunologia , Hipersensibilidade Tardia/patologia , Masculino , Valor Preditivo dos Testes , Reprodutibilidade dos Testes , Índice de Gravidade de Doença , Pele/imunologia , Pele/patologia , Testes Cutâneos , Fatores de Tempo
6.
Acta Orthop Belg ; 82(2): 271-274, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27682288

RESUMO

The aim of the current study was to assess the changes of plantar foot pressures with pedobarography in -patients with Achilles tendon repair by minimally -invasive surgical technique. This retrospective study consisted of 15 consecutive patients who were treated for acute Achilles' tendon repair with minimally invasive technique in our clinic in a two year period between 2010 and 2012. All patients were male. The mean age was 28.7 years (24-42) and the mean follow-up time was 2.3 years (1.5- 3). All patients had sports related Achilles' tendon rupture and all had undergone surgery in 24-48 hours. After surgery, extremity was immobilized with short leg cast for 6 weeks. Peak and mean heel and forefoot pressures in injured extremity were measured by -pedobarograph and compared with noninvolved foot. There wasn't any complication associated with -surgery such as wound problems, re rupture or -neurologic injury. Only three patients had some numbness at the incision site. When we compare the mean foot pressures between the operated foot and the normal foot, there was no statistical difference about peak and mean heel and forefoot plantar pressure between involved site and non involved site. As a result, Achilles tendon repair with minimal invasive technique and early rehabilitation may prevent changes of plantar foot pressure distribution.


Assuntos
Tendão do Calcâneo/lesões , Tendão do Calcâneo/cirurgia , Pé/fisiologia , Procedimentos Cirúrgicos Minimamente Invasivos , Tendão do Calcâneo/fisiopatologia , Adulto , Humanos , Masculino , Pressão , Estudos Retrospectivos , Ruptura/fisiopatologia , Ruptura/cirurgia , Resultado do Tratamento , Adulto Jovem
7.
Acta Endocrinol (Buchar) ; 12(2): 219-223, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-31149090

RESUMO

Calciphylaxis, also known as calcific uremic arteriolopathy (CUA), is usually observed in women and it is a serious complication of hyperparathyroidism secondary to chronic renal failure. CUA is characterized by ischemic tissue loss secondary to progressive vascular degeneration. Although it is rare, it may end up with sepsis and organ failure and can be fatal. Its pathogenesis is not fully understood, but it is thought that it occurs secondary to increased calcification activators such as oxidized LDL, TNF- α, calcitriol, fibronectin, collagen-I, and TGF-1α. The most effective treatment is managing underlying pathology and decreasing serum calcium and phosphorus levels. In this report, we aimed to present an end stage renal failure case with coexisting hyperparathyroidism, hyperthyroidism and calciphylaxis in whom cutaneous manifestations were healed 6 months after parathyroidectomy.

8.
Acta Endocrinol (Buchar) ; 12(1): 72-76, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-31258804

RESUMO

BACKGROUND: Occult papillary thyroid carcinoma presented as isolated cervical lymphadenopathy without clinical and radiologic findings has been rarely reported. CASE REPORT: A 47 years old female patient admitted to otorhinolaryngology clinic with 4X3 cm sized cervical mass. Physical examination of the patient was noted as a nontender, firm, mobile lymph node at right lateral cervical region. There was no inflammatory or infection disease in the history of patients anamnesis and no abnormal value on laboratory tests. Ultrasound screening of the neck detected a lymph node with suspicious features for malignancy. Head and neck examination was normal and there is no evidence of a tumoral mass or nodule in the thyroid gland. Whole body scan of MRI showed no pathologic sign both in the neck and body. Excisional biopsy was performed and revealed a carcinoma with papillary morphology. Immunohistochemical staining features of the tumor confirmed a papillary carcinoma derived from the thyroid gland. Second look USG of the neck and thyroid was performed but it revealed no tumoral mass. The patient underwent total thyroidectomy with right functional and central lymph node dissection. Histological examination of the thyroid gland showed multicentric 2 mm sized, three foci of papillary carcinoma located in bilateral thyroid lobes and metastatic lymph nodes in the right side of the neck. CONCLUSION: A metastatic cervical lymph node can be evidence of a clinically undetected occult papillary thyroid carcinoma. Specific immunohistochemistry staining of specimen may lead to appropriate surgery and progression of carcinoma may be hindered by application of additional RAI therapy.

9.
J Pediatr Gastroenterol Nutr ; 61(1): 69-73, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-26039942

RESUMO

OBJECTIVES: The dietary protein proctocolitis, also known as allergic proctocolitis (AP), is characterized by the presence of mucoid, frothy, and bloody stools in an otherwise healthy infant. The aim of this study was to describe a group of children with AP, diagnosed according to the criterion-standard method, food challenge to provide clinicians with more information on typical presentation, and an overview on nutritional management strategies and prognosis. METHODS: We collected data on infants with AP in our allergy and gastroenterology outpatient clinics. Any other conditions that may cause bloody diarrhea were ruled out. Skin prick tests and atopy patch tests were performed for diagnosis, and patients were studied for resolution. To the patients whose rectal bleeding did not recover with oligoantigenic maternal diet in addition to amino acid-based formula, endoscopic evaluation was performed to confirm the diagnosis and to exclude other reasons of rectal bleeding. RESULTS: Sixty patients were diagnosed as having AP. The age of onset was 1.7 ±â€Š1.32 months. All of the patients were triggered by milk, 6.6% with milk and egg, 3.3% with milk and chicken, 1.7% with milk and wheat, 1.7% with milk and potato, and 3.3% had multiple food allergy. 53.3% (n = 32) acquired tolerance by age 1, 25.0% (n = 15) by 2 years, 5% (n = 3) by 3, and 1.7% (n = 1) by 4 years. CONCLUSIONS: Milk was a triggering factor for all of the patients. Resolution of AP is usually within 1 year but symptoms of some patients may continue even longer. An extension of the follow-up period is required according to our study.


Assuntos
Dieta/efeitos adversos , Proteínas Alimentares/imunologia , Hipersensibilidade Alimentar/complicações , Leite/imunologia , Proctocolite/etiologia , Idade de Início , Animais , Dermatite Atópica/etiologia , Feminino , Hipersensibilidade Alimentar/sangue , Hemorragia Gastrointestinal/etiologia , Humanos , Imunoglobulina E/sangue , Lactente , Recém-Nascido , Masculino , Hipersensibilidade a Leite/sangue , Hipersensibilidade a Leite/complicações , Proctocolite/sangue , Proctocolite/diagnóstico , Proctocolite/imunologia , Prognóstico
11.
Allergy Asthma Proc ; 36(5): 386-93, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26314820

RESUMO

BACKGROUND: Nonsteroidal anti-inflammatory drugs (NSAID) are the second-most frequent drugs that cause hypersensitivity reactions among children. Studies related to NSAIDs hypersensitivity in children are limited. In this study, we aimed to evaluate children admitted with suspicion of NSAIDs reaction. METHOD: Between January 1, 2011, and November 30, 2014, we included patients with suspicion of NSAIDs hypersensitivity in our clinic. For evaluation, skin tests and oral provocation tests with the drug (suspected or alternative) were proposed. Reactions were classified and defined according to the latest European Academy of Allergy and Clinical Immunology position paper on NSAID hypersensitivity. RESULTS: During the study period, 123 patients (with 136 drug reactions) were admitted to our clinic with suspected NSAID hypersensitivity. The mean (standard deviation) age of the patients, 67 female (55%), was 83.10 ± 56.05 months. Thirteen patients described reactions to more than one chemically unrelated NSAID, and 110 patients described reactions with chemically similar drugs. Eight patients were not included because they did not have provocation tests. Thus, 115 patients were evaluated. A hundred and thirty provocations were performed. Twenty patients (17.4%) were diagnosed with NSAID hypersensitivity (13 patients diagnosed by provocation tests and 7 patients diagnosed according to their history). The most frequently encountered agent was ibuprofen (50% [10/20]). Eighty percent (16 patients) of the reactions were considered "non-cross-reactive type." Fifteen patients (75%) were classified as having single-NSAID-induced urticaria and/or angioedema, three patients were classified as having NSAID-induced urticaria and/or angioedema, one patient was classified as having NSAID-exacerbated respiratory disease, and the other patients were classified as having single-NSAID-induced delayed hypersensitivity reactions. CONCLUSION: Detailed history and drug provocation tests are important to verify NSAID hypersensitivity. The most common type is the non-cross-reactive type, and, in our study, the most common responsible drug was ibuprofen.


Assuntos
Alérgenos/uso terapêutico , Anti-Inflamatórios não Esteroides/uso terapêutico , Hipersensibilidade a Drogas/diagnóstico , Ibuprofeno/uso terapêutico , Acetaminofen/uso terapêutico , Administração Oral , Anti-Inflamatórios não Esteroides/efeitos adversos , Anti-Inflamatórios não Esteroides/classificação , Criança , Pré-Escolar , Reações Cruzadas , Hipersensibilidade a Drogas/terapia , Feminino , Humanos , Ibuprofeno/efeitos adversos , Imunização , Lactente , Masculino , Testes Cutâneos
12.
Pediatr Allergy Immunol ; 25(7): 685-90, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25283219

RESUMO

BACKGROUND: The negative predictive value of the drug provocation test is important for both the patient and the physician. However, in children, this predictive value is unresolved. METHODS: The study included patients who had drug provocation test with a suspected drug and was diagnosed as 'not allergic to the drug'. Three months after allergy workup, the patients were contacted and asked for reexposure to the tested drug. Patients who have reported reactions during reexposure were reevaluated with skin tests and drug provocation. RESULTS: During the study period, 217 provocations were performed to 203 patients. Of these, 163 patients (80.3%) with 175 negative drug provocation tests could be contacted. Ninety-one (52%) of the 175 cases reported to use the tested drug again, and 11 (12%) of these cases declared that they had a new reaction. Two of the eleven cases refused reevaluation. Nine cases were evaluated by drug allergy workup. Two of the nine cases were classified as allergic after retests. Collectively, the negative predictive value was 95.6% (87 of 91 cases) for all drug challenges. CONCLUSIONS: The negative predictive value of the drug provocation test is abundant in children; however, negative drug provocation tests do not necessarily predict tolerance for the drug.


Assuntos
Alérgenos/imunologia , Antibacterianos/imunologia , Anti-Inflamatórios não Esteroides/imunologia , Hipersensibilidade a Drogas/diagnóstico , Imunização/métodos , Administração Oral , Adolescente , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Masculino , Valor Preditivo dos Testes , Testes Cutâneos
13.
Appl Radiat Isot ; 205: 111169, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38157794

RESUMO

SrGd2O4 phosphors doped with Eu3+ were successfully synthesized through a sol-gel combustion method, covering a range of dopant concentrations from 0.25 mol% to 3 mol%. The structural analysis of these phosphor materials was comprehensively conducted utilizing various techniques, including X-ray powder diffraction analysis (XRD), Energy Dispersive X-ray (EDX), and Fourier-transform infrared spectroscopy (FTIR). In addition to unveiling the structural characteristics, these analyses provide valuable insights into the compositional aspects, enhancing our understanding of the synthesized SrGd2O4:Eu3+ phosphors across different doping levels. XRD analysis findings validate the successful generation of the intended SrGd2O4 host, demonstrating orthorhombic system structures consistent with JPCD card number 98-019-3592. FTIR analyses conducted on the phosphor samples not only identify bending modes but also reveal intricate details about small vibration bonds within the material. When excited by the 349 nm laser, SrGd2O4:xEu3+ phosphors exhibit distinct photoluminescence (PL) properties like red emission at 614 nm from Eu3+. From the emission spectra, one can clearly observe that Eu3+ with an ionic radius close to the Gd3+ ion preferentially occupies the symmetry sites of the host lattice. The optimal doping concentration was determined to be 0.5 mol%, as revealed by the data in our study. Additionally, a deeper understanding of the luminescence quenching mechanism was attained, pinpointing the involvement of dipole-dipole (d-d) energy transfer in this intriguing phenomenon. This optimal concentration not only enhances the material's properties but also underscores the pivotal role of d-d interactions in governing the luminescence behavior within the doped system.

14.
Spectrochim Acta A Mol Biomol Spectrosc ; 321: 124711, 2024 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-38941750

RESUMO

In this study, an investigation was conducted on the structural and photoluminescence (PL) characteristics of LaAl2B4O10 (LAB) phosphors initially incorporated with Dy3+ and Eu3+ ions. Subsequently, the impact of varying Eu3+ concentration while maintaining a constant Dy3+ concentration was examined. Structural characterization was performed using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and energy-dispersive X-ray spectroscopy (EDS). XRD analysis confirmed the effective embedding of both dopants into the hexagonal framework of the LAB. The PL emission spectra revealed characteristic emissions of Dy3+ (blue and yellow) and Eu3+ (red) ions. The optimized dopant concentrations of both Dy3+ and Eu3+ were observed to be 3 wt%. The dominant mechanism for concentration quenching in doped LAB phosphors was determined to be the electric dipole-dipole interaction. Co-doping with Eu3+ led to a substantial decrease in Dy3+ emission intensity (∼0.18-fold) while enhancing Eu3+ emission intensity (∼3.72-fold). The critical energy transfer distance (RC = 11.64 Å) and the analysis based on the Dexter theory confirmed that the energy transfer mechanism corresponds to dipole-dipole interaction. The color purities and correlated color temperatures (CCT) were estimated, suggesting the potential of these phosphors for warm white and red lighting applications, respectively. The observed energy transfer and luminescence properties, along with the structural and compositional characterization, highlight the promising potential of LAB:Dy3+/Eu3+ co-doped phosphors for advanced lighting and display technologies.

15.
Appl Radiat Isot ; 208: 111308, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38555847

RESUMO

This study explores the structural and optical qualities of LaCa4O(BO3)3 (LACOB) phosphors doped with Eu3+, Dy3+, and Tb3+ using a microwave-assisted sol-gel technique. It uncovers oxygen-related luminescence defects in LACOB, highlighting emission peaks at 489 and 585 nm for Dy3+, a distinct sharp peak at 611 nm for Eu3+ in the red spectrum, and a notable green emission for Tb3+ due to specific transitions. The photoluminescence (PL) analysis indicates that luminescence is optimized through precise doping, leveraging dipole interactions, and localized resonant energy transfer, which are influenced by dopant concentration and spatial configuration. Temperature studies show emission intensity variations, particularly noticeable below 100 K for Tb3+ doped samples, demonstrating the nuanced balance between thermal quenching and luminescence efficiency. This temperature dependency, alongside the identified optimal doping conditions, underscores the potential of these materials for advanced photonic applications, offering insights into their thermal behavior and emission mechanisms under different conditions.

16.
Appl Radiat Isot ; 206: 111214, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38324934

RESUMO

An investigation into the luminescent behavior of YCOB (Yttrium Calcium Oxyborate) doped with Eu3+ and Dy3+ ions, synthesized via the combustion method, is presented. The study, employing X-ray diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR), and Energy-Dispersive X-ray Spectroscopy (EDS) analyses, confirms the structural integrity and purity of the synthesized nanophosphors. An XRD pattern exhibiting distinct crystalline peaks indicates that the dopant ions were successfully integrated into the YCOB lattice. The photoluminescence (PL) response of YCOB with Eu3+ and Dy3+ ions is thoroughly examined, uncovering distinct excitation and emission spectra. In the case of Eu3+ doping, excitation spectra reveal a significant charge transfer (CT) band at 254 nm, indicative of electron transfer between oxygen and europium ions. This CT transition enhances our understanding of the excitation behavior, with the dominant and Laporte-forbidden 5D0 → 7F2 transition. Characteristic peaks at 345 nm in the excitation spectra efficiently stimulate YCOB:Dy3+ when Dy3+ is used as a dopant. The primary emission peak at 585 nm corresponds to the hypersensitive electric dipole transition 4F9/2-6H13/2. Concentration quenching phenomena are observed, with a maximum Eu3+ concentration of 7 wt % attributed to the dipole-quadrupole interaction. Dy3+ doping, with a maximum concentration of 2 wt % primarily shows multipolar interactions, especially dipole-dipole interactions. The study extends to CIE chromaticity analysis, emphasizing Eu3+ doping's suitability for white light-emitting diode (WLED) applications and ensuring color stability. Conversely, varying Dy3+ concentrations do not yield consistent chromaticity coordinates. These findings have significant implications for the development of advanced phosphor materials across diverse applications, offering a roadmap for optimizing their optical performance.

17.
Appl Radiat Isot ; 214: 111529, 2024 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-39332268

RESUMO

This study investigates the structural and photoluminescence (PL) characteristics of Tb3+-incorporated K3Y(BO2)6 (KYBO) phosphors synthesized via a microwave-assisted sol-gel technique. X-ray diffraction (XRD) and Rietveld refinement confirmed the formation of a pure hexagonal phase, with lattice expansion due to Tb³âº doping. PL studies revealed strong green emissions centered at 541 nm, attributed to the 5D4 → 7F5 transitions of Tb³âº ions, with the highest intensity observed at 5 wt% Tb³âº. A decrease in emission was observed at higher concentrations due to concentration quenching. Temperature-dependent PL measurements revealed reverse thermal quenching enhancing PL intensity. Chromaticity analysis based on CIE 1931 coordinates showed stable green emission across all concentrations, with a maximum color purity of 89.74% observed for the KYBO:3 wt% Tb³âº sample. The results, along with reverse thermal quenching behavior observed between 470K and 550K, suggest that these phosphors exhibit excellent potential for lighting and display technologies.

18.
Appl Radiat Isot ; 210: 111380, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38830278

RESUMO

This study explores the structural and luminescent properties of terbium (Tb³âº)-doped lanthanum aluminium borate (LaAl2B4O10, abbreviated as LAB) phosphors, a novel host lattice for Tb³âº doping. LAB:Tb³âº phosphors, with varying dopant concentrations, were synthesized using a microwave-assisted combustion synthesis approach and characterized using X-ray diffraction (XRD), Rietveld refinement, and photoluminescence spectroscopy at both room and low temperatures. The structural analysis confirmed the hexagonal crystal structure of LAB and revealed successful incorporation of Tb³âº ions without altering the fundamental lattice. Luminescence studies demonstrated that the LAB:Tb³âº phosphors show strong green emission primarily attributed to the 5D4→7F5 transition of Tb³âº. The optimal doping concentration was determined to be 5 wt% Tb³âº, which provided maximum luminescence efficiency. This concentration also allowed for a critical study of energy transfer mechanisms within the phosphor, revealing dipole-dipole interactions with a critical distance of 9.80 Å between Tb³âº ions. Additionally, the CIE chromaticity coordinates of LAB:0.05 Tb³âº were precisely determined to be (0.289, 0.4460), indicating the potential for high-quality green emission suitable for solid-state lighting and display technologies. This work not only demonstrates the potential of LAB:Tb3+ as a highly efficient green luminescent material, but also sheds light on the mechanisms responsible for energy transfer and concentration quenching.

19.
Appl Radiat Isot ; 208: 111301, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38522263

RESUMO

This study examines the thermoluminescent (TL) properties of undoped Ca4YO(BO3)3 phosphor, focusing on how it behaves under a variety of experimental conditions. The IRSL-TL 565 nm was chosen as the appropriate detection filter among various optical detection filter combinations. During the preheating trials conducted at a rate of 2 °C/s, the TL peak exhibited increased intensity, particularly around 200 °C. The experimental outcomes demonstrated a reliable linear relationship (R2 = 0.996 and b = 1.015) in the dose response of undoped preheated Ca4YO(BO3)3 within the range of 1-200 Gy. The investigation encompasses a range of techniques, including the TM-Tstop method, computerized glow curve deconvolution (CGCD) analysis, and theoretical modelling. The application of the TM-Tstop method to samples irradiated with a 5 Gy dose revealed distinct zones on the TM versus Tstop diagram, signifying the presence of at least two discernible components within the TL glow curve, specifically, a single general order kinetics peak and a continuous distribution. The analysis of activation energy versus preheated temperature exhibited a stepwise curve, indicating five trap levels with depths ranging between 1.13 eV and 1.40 eV. The CGCD method also revealed the superposition of at least five distinct TL glow peaks. It was observed that their activation energies were consistent with the Tm-Tstop experiment. Furthermore, the low Figure of Merit (FOM) value of 1.18% indicates high reliability in the goodness-of-fit measure. These findings affirm the reliability and effectiveness of the employed methods in characterizing the TL properties of the Ca4YO(BO3)3 phosphor under investigation. Theoretical models, including the semi-localized transition model, were introduced to explain anomalous observations in TL glow peak intensities and heating rate patterns. While providing a conceptual framework, these models may require adjustments to accurately capture the specific characteristics uncovered through CGCD analysis. As a potential application, the study suggests that the characterized TL properties of Ca4YO(BO3)3 phosphor could be utilized in dosimetric applications, such as radiation dose measurements, owing to its reliable linear response within a broad dose range.

20.
Pediatr Allergy Immunol ; 24(5): 456-62, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23772635

RESUMO

BACKGROUND: Although food allergy is an important health problem in Western countries, the prevalence varies among geographic regions. There is limited data on the prevalence of food allergy especially for adolescent age group, and the data from Turkey and Mediterranean region are even scarce. METHODS: The study is a cross-sectional survey including a questionnaire followed by phone survey with families that have reported food allergy and clinical evaluation of children having a history compatible with food allergy after phone survey. The sample number of students has been calculated 9096 of a total of 210.000 students at the second stage (6th, 7th, and 8th grades) of state elementary schools in the metropolitan counties of Ankara province with the assumption of food allergy prevalence (P) = 1% and a δ value = 0.2 (α < 0.05, ß = 0.8). RESULTS: Of 11,233 questionnaires distributed at 34 schools, 10,096 (89.4%) have been returned. The number of reported food allergy was 1139 (11.2%), and it was reduced to 133 (1.3%) after phone survey. After clinical evaluation by skin test, specific IgE and double-blind placebo-controlled food challenge (DBPCFC), proven IgE-mediated food allergy was determined in 15 (0.15%) children. The foods most commonly resulting food allergy were peanut 0.05% and treenuts 0.05%. CONCLUSION: The prevalence of food allergy among adolescent age group has been confirmed to be comparatively low in Turkey. Peanuts and treenuts were determined to be the most common causes of IgE-mediated food allergy.


Assuntos
Alérgenos/imunologia , Arachis/imunologia , Hipersensibilidade a Amendoim/epidemiologia , Adolescente , Criança , Estudos Transversais , Feminino , Humanos , Imunoglobulina E/imunologia , Imunoglobulina E/metabolismo , Masculino , Hipersensibilidade a Amendoim/imunologia , Prevalência , Turquia
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