RESUMO
Leishmaniasis causes significant morbidity and mortality worldwide. In our country, there has been a significant increase in the number of cases of leishmaniasis in the last decade. In our study, the effects of Hypericum thymbrifolium, Hypericum scabrum and Eryngium creticum plant extracts were tested on Leishmania major, Leishmania tropica and Leishmania infantum/donovani, which were clinically resistant by not responding to Glucantime® therapy. Cytotoxicity of these extracts were evaluated by XTT method in the human fibroblast cell line. Possible active ingredients were detected by GC-MS analysis from plant extracts. Glucantime® resistance was detected at concentrations of 50 µg/mL and lower in 4 of the 7 strains tested. No living leishmania parasites were found in leishmania strains treated with plant extracts at concentrations of 100 µg/mL or higher. The concentrations of plant extracts included in the study on the WI-38 human fibroblast cell line were not cytotoxic. According to the GC-MS analysis, several active substances with biological activities and anti-parasitic effects, such as Thiophene, Germacrene-D, trans-Geranylgeraniol, Pyridine, and Maleimides, were identified. Based on the findings of the study, it is believed that these identified active substances when supported by in-vivo studies, will pave the way for future research and have the potential to be developed as anti-leishmania drugs.
Assuntos
Eryngium , Hypericum , Leishmania infantum , Leishmania major , Leishmania tropica , Extratos Vegetais , Extratos Vegetais/farmacologia , Extratos Vegetais/química , Humanos , Hypericum/química , Leishmania infantum/efeitos dos fármacos , Leishmania tropica/efeitos dos fármacos , Leishmania major/efeitos dos fármacos , Linhagem Celular , Eryngium/química , Antiprotozoários/farmacologia , Fibroblastos/efeitos dos fármacos , Leishmania donovani/efeitos dos fármacos , Cromatografia Gasosa-Espectrometria de MassasRESUMO
@#Leishmaniasis causes significant morbidity and mortality worldwide. In our country, there has been a significant increase in the number of cases of leishmaniasis in the last decade. In our study, the effects of Hypericum thymbrifolium, Hypericum scabrum and Eryngium creticum plant extracts were tested on Leishmania major, Leishmania tropica and Leishmania infantum/donovani, which were clinically resistant by not responding to Glucantime® therapy. Cytotoxicity of these extracts were evaluated by XTT method in the human fibroblast cell line. Possible active ingredients were detected by GC-MS analysis from plant extracts. Glucantime® resistance was detected at concentrations of 50 µg/mL and lower in 4 of the 7 strains tested. No living leishmania parasites were found in leishmania strains treated with plant extracts at concentrations of 100 µg/mL or higher. The concentrations of plant extracts included in the study on the WI-38 human fibroblast cell line were not cytotoxic. According to the GC-MS analysis, several active substances with biological activities and anti-parasitic effects, such as Thiophene, Germacrene-D, trans-Geranylgeraniol, Pyridine, and Maleimides, were identified. Based on the findings of the study, it is believed that these identified active substances when supported by in-vivo studies, will pave the way for future research and have the potential to be developed as anti-leishmania drugs.
RESUMO
The aim of this study was to determine the effects of multi-purpose activities on the quality of life of elderly individuals living either in a nursing home or in their own homes. Sixty-seven volunteers aged >60 were surveyed: 34 living in a nursing home and 33 living at-home. Participants performed activities consisting of physical, cognitive tasks, and handicrafts twice weekly for 12 weeks. Each participant completed the 36-item Short Form Health Survey both before and after the program, and the results were compared between the groups. At the completion of the program, the general health, vitality, physical functioning, physical role, energy level, and social functioning parameters of the survey of the at-home group were better than were those of the nursing home group. When the data of both groups were compared, an improvement in the social functioning, general health, physical functioning, energy level, and mental health parameters were seen for the at-home group, but not among the nursing home participants. Companionship enabled easy and efficient performance of activities of at-home participants, thereby positively affecting their quality of lives.
Assuntos
Atividades Cotidianas , Qualidade de Vida , Idoso , Humanos , Qualidade de Vida/psicologia , Atividades Cotidianas/psicologia , Casas de Saúde , Inquéritos Epidemiológicos , Inquéritos e QuestionáriosRESUMO
BACKGROUND: Pulmonary arterial hypertension (PAH), is a rare manifestation of systemic lupus erythematosus (SLE), characterized by pulmonary arterial remodeling leading to right ventricular failure and death. To date, optimal management of SLE-associated PAH should be clarified, especially regarding the respective places of immunosuppressants and PAH vasodilator treatments. CASE REPORT: We report the case of a 48-year-old woman with SLE and secondary Sjogren syndrome, associated with severe PAH and lupus peritonitis with massive ascites, who showed a remarkable response, both for SLE flare and PAH, to a treatment combining immunosuppressants and pulmonary arterial vasodilator treatment. CONCLUSION: This observation highlights the interest of combining immunosuppressive therapy in SLE-PAH, whose modalities in association with PAH treatments should be clarified.
Assuntos
Imunossupressores/uso terapêutico , Lúpus Eritematoso Sistêmico/tratamento farmacológico , Hipertensão Arterial Pulmonar/tratamento farmacológico , Vasodilatadores/uso terapêutico , Ascite/etiologia , Feminino , Humanos , Lúpus Eritematoso Sistêmico/complicações , Pessoa de Meia-Idade , Hipertensão Arterial Pulmonar/etiologia , Síndrome de Sjogren/complicaçõesRESUMO
An internal consistency test of the calculation of coincidence-summing correction factors FC for volume sources is presented. The test is based on exact equations relating the values of FC calculated for three ideal measurement configurations. The test is applied to a number of 33 sets of FC values sent by 21 teams. Most sets passed the test, but not the results obtained using the quasi-point source approximation; in the latter case the test qualitatively indicated the magnitude of the bias of FC.
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BACKGROUND: Biomarkers play an important role in the risk stratification of patients with heart failure (HF). Recent studies have shown that soluble suppression of tumorigenicity 2 (sST2), a member of the interleukin 1 receptor family, is associated with disease prognosis in acute and chronic HF. In this study we aimed to investigate the relation between sST2 level and functional capacity in outpatients with systolic HF. PATIENTS AND METHODS: This study included 120 HF patients with reduced ejection fraction (HFrEF; EF ≤ 40%). The mean age of patients was 66 ± 11 years. Advanced HF (New York Heart Association [NYHA] functional class III-IV) was observed in 35 patients (29%). RESULTS: sST2 levels were on average higher in patients with NYHA functional classes III and IV than in patients with NYHA functional classes I and II (51 [9-198] vs. 25 ng/ml [9-118], p < 0.001). In a multiple logistic regression model, sST2 level (OR: 1.044, p = 0.004, 95% CI: 1.014-1.075), hemoglobin level (OR: 0.590, p = 0.001, 95% CI: 0.433-0.805), total cholesterol level (OR: 0.977, p = 0.004, 95% CI: 0.962-0.993), and age (OR: 1.066, p = 0.047, 95% CI: 1.001-1.136) were associated with poor functional capacity. In receiver operating characteristic (ROC) curve analysis, the optimal cut-off value of sST2 for predicting poor functional capacity was >42 ng/ml, with 63% sensitivity and 88% specificity (AUC: 0.810, 95% CI: 0.728- 0.875). CONCLUSION: Higher sST2 levels were strongly associated with poor NYHA functional class, independent of cardiac risk factors, in outpatients with HFrEF.
Assuntos
Biomarcadores , Insuficiência Cardíaca , Idoso , Biomarcadores/sangue , Feminino , Insuficiência Cardíaca/sangue , Insuficiência Cardíaca/diagnóstico , Humanos , Proteína 1 Semelhante a Receptor de Interleucina-1 , Masculino , Pessoa de Meia-Idade , Pacientes Ambulatoriais , Prognóstico , Volume Sistólico , Função Ventricular EsquerdaRESUMO
BACKGROUND: The current study aimed to evaluate the influence of regular annual influenza vaccinations on cardiovascular (CV) death and heart failure-related hospitalizations (HFrH) in stable outpatients with heart failure with reduced ejection fraction. METHODS: The Turkish research team-HF (TREAT-HF) is a network undertaking multicenter, observational cohort studies in HF. This study is a subgroup analysis of TREAT-HF outpatient cohorts who completed a questionnaire on influenza vaccination status and for whom follow-up data were available. A total of 656 patients with available follow-up data for CV death and HFrH including recurrent hospitalization were included in the study. Patients were classified into two groups: those who received regular influenza vaccination (40 %) and those who did not receive vaccination. RESULTS: During a mean follow-up of 15 ±6 months, 113 (18 %) patients had CV death and 471 (72 %) patients had at least one HFrH. The CV death rate was similar in both groups of patients (16 vs. 19 %, p = 0.37), whereas, HFrH and recurrent HFrH were significantly less frequently encountered in patients who received regular influenza vaccination than in those who did not receive vaccination (43 vs. 92 % and 16 vs. 66 %, p < 0.001, respectively). In a multivariate Cox proportional hazards model - in addition to a few clinical factors - vaccination status (HR = 0.30, 95 % CI = 0.17-0.51, p < 0.001) and graduation from university (HR = 0.35, 95 % CI = 0.17-0.72, p = 0.004) remained independently associated with the risk of recurrent HFrH. CONCLUSION: Regular influenza vaccination does not influence CV deaths; however, it decreases HFrH including recurrent episodes of HFrH in outpatients with heart failure with reduced ejection fraction.
Assuntos
Morte Súbita Cardíaca/epidemiologia , Insuficiência Cardíaca/mortalidade , Vacinas contra Influenza/uso terapêutico , Influenza Humana/mortalidade , Influenza Humana/prevenção & controle , Readmissão do Paciente/estatística & dados numéricos , Vacinação/estatística & dados numéricos , Comorbidade , Morte Súbita Cardíaca/prevenção & controle , Feminino , Seguimentos , Insuficiência Cardíaca/prevenção & controle , Humanos , Masculino , Pessoa de Meia-Idade , Prevalência , Fatores de Risco , Turquia/epidemiologiaRESUMO
OBJECTIVE: Elevated cancer antigen 125 (CA-125) levels are associated with cardiopulmonary disorders such as acute and chronic heart failure (HF), coronary artery disease, chronic obstructive pulmonary disease, and atrial fibrillation (AF). The development of atrial fibrillation (AF) is related to morbidity and mortality in patients with HF: therefore, it is important to identify patients with increased risk for development of AF. We investigated whether plasma CA-125 levels in patients with hospitalized systolic HF could predict the development of AF. PATIENTS AND METHODS: A total of 149 consecutive patients with sinus rhythm who were admitted to the emergency department with hospitalized systolic HF were evaluated prospectively. Serum CA-125 levels were obtained after initial stabilization during their hospital stay. RESULTS: AF developed in 36 (% 24.2) patients during a follow-up period of 22.1 ± 11 months (range 3-61). CA-125 levels were significantly higher in patients who developed AF than in patients with sinus rhythm [99 U/ml (48-172) vs. 47 U/ml (18-108), p = 0.001]. The optimal cut-off level of CA-125 to predict development of AF was found to be > 68.49 U/ml. CA-125 > 68.49 U/ml, left atrial diameter, right ventricular dilatation, moderate to severe mitral and tricuspid regurgitations were found to have prognostic significance in univariate analysis. In a multivariate Cox proportional hazards model with the backward stepwise method, CA-125 > 68.49 U/ml (HR = 2.693, % 95 CI = 1.285-5.641, p = 0.009) and moderate to severe mitral regurgitation (HR = 2.708, % 95 CI = 1.295-5.663, p = 0.008) were associated with an increased risk of new-onset AF after adjustment for variables found to be statistically significant in univariate analysis and correlated with CA-125 level. CONCLUSION: CA-125 level is associated with the development of AF in patients with hospitalized systolic HF.
Assuntos
Fibrilação Atrial/sangue , Fibrilação Atrial/epidemiologia , Antígeno Ca-125/sangue , Insuficiência Cardíaca/sangue , Insuficiência Cardíaca/epidemiologia , Hospitalização/estatística & dados numéricos , Fibrilação Atrial/diagnóstico , Biomarcadores/sangue , Comorbidade , Feminino , Insuficiência Cardíaca/diagnóstico , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Prognóstico , Reprodutibilidade dos Testes , Medição de Risco/métodos , Sensibilidade e Especificidade , Turquia/epidemiologiaRESUMO
The energy dependence of the response of BC-408 plastic scintillator (PS), an approximately water-equivalent material, has been investigated by employing standardized x-ray beams. IEC RQA and ISO N series x-ray beam qualities, in the range of 40-100 kVp, were calibrated using a PTW-type ionization chamber. The energy response of a thick BC-408 PS detector was measured using the multichannel pulse height analysis method. The response of BC-408 PS increased gradually with increasing energy in the energy range of 40-80 kVp and then showed a flat behavior at about 80 to 120 kVp. This might be due to the self-attenuation of scintillation light by the scintillator itself and may also be partly due to the ionization quenching, leading to a reduction in the intensity of the light output from the scintillator. The results indicated that the sensitivity drop in BC-408 PS material at lower photon energies may be overcome by adding some high-Z elements to its polyvinyltoluene (PVT) base. The material modification may compensate for the drop in the response at lower photon energies. Thus plastic scintillation dosimetry is potentially suitable for applications in diagnostic radiology.
Assuntos
Fótons , Plásticos , Contagem de Cintilação/instrumentação , Contagem de Cintilação/métodos , Calibragem , Método de Monte Carlo , Raios XRESUMO
OBJECTIVES: ST segment elevation myocardial infarction (STEMI) is an important cause of the morbidity and mortality in coronary artery disease. The aim of this study is to investigate the relationship between hematologic parameters and post primary PCI coronary no-reflow. PATIENTS AND METHODS: A total of 145 consecutive STEMI patients (mean age=58.2±12.3 years) and healthy volunteer admitted within 6 hours from symptom onset were enrolled to the study in the cardiology clinics. The STEMI patients were divided into 2 groups based on the Thrombolysis In Myocardial Infarction (TIMI) flow grade. No-reflow was defined as post-PCI TIMI Flow Grade 0, 1 or 2 and angiographic success was defined as TIMI Grade 3 Flow. RESULTS: Diabetes mellitus hypertension and smoking status were similar between groups. With respect to baseline laboratory status, fasting glucose, blood urea nitrogen, creatinine levels were not significantly different between groups. The neutrophil/lymphocyte (N/L) ratio was also significantly higher in STEMI group (7.1±4.6 vs. 2.3±1.7, p < 0.001). Additionally, N/L ratio was also significantly higher in No-reflow group (TIMI Flow Grade 0, 1 or 2) group (13.1±4.5 vs. 5.3±2.7, p < 0.001). CONCLUSIONS: The N/L ratio, which is cheaply and easily measurable laboratory data is independently associated with post primary PCI coronary no-reflow.
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Linfócitos/metabolismo , Infarto do Miocárdio/fisiopatologia , Neutrófilos/metabolismo , Fenômeno de não Refluxo/epidemiologia , Idoso , Estudos de Casos e Controles , Angiografia Coronária , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Infarto do Miocárdio/terapia , Intervenção Coronária Percutânea/métodosRESUMO
A performance study was performed for CdZnTe coplanar grid (CPG) detectors when used as γ-ray spectrometers. The detectors have the crystal volumes of 1, 1.6875 and 2.25 cm(3), respectively. Time stability of each CdZnTe CPG detector was investigated in a long-term operation (time span of 0.25 to about 100 h). The spectroscopic performances were measured at different bias voltages and at various photon energies ranging from 59.6 keV ((241)Am) to 1332.5 keV ((60)Co) for each detector, and evaluated by using the following parameters: energy resolution in FWHM, peak tailing in peak-to-valley (P/V) ratio and in FWHM/FW.25 M ratio, and photofraction using the acquired γ-ray spectra. No polarization effect was observed in terms of count rate, energy resolution and peak centroid shift. The obtained results indicate that better time stability and excellent spectroscopic performances of the present CdZnTe CPG detectors are shown for a room temperature γ-ray spectroscopy.
RESUMO
In the γ-ray spectrometric analysis of the radionuclides, a correction factor is generally required for the spectral interfering γ-rays in determining the net areas of the analytical peaks because some interfering γ-rays often might contribute to the analytical peaks of interest. In present study, a correction methodology for the spectral interfering γ-rays (CSI) is described. In particular, in the analysis of (232)Th contained in samples, the interfering γ-rays due to (226)Ra, (235)U, (238)U and their decay products often overlap to the peaks of interest from (232)Th decay products, and vise versa. For the validation of the proposed CSI method, several certified reference materials (CRM) containing U and Th were measured by using a 76.5% efficient n-type Ge detector. The required correction factors were quantified for spectral interference, self-absorption and true coincidence summing (TCS) effects for the relevant γ-rays. The measured results indicate that if one ignores the contributions of the interfering γ-rays to the analytical peaks at 583.2 keV of (208)Tl and 727.3 keV of (212)Bi, this leads to a significantly systematic influence on the resulted activities of (232)Th. The correction factors required for spectral interference and TCS effects are estimated to be â¼13.6% and â¼15.4% for 583.2 keV peak. For the 727.3 keV peak, the correction factor is estimated to be â¼15% for spectral interference, and â¼5% for the TCS effects at the presently used detection geometry. On the other hand, the measured results also indicate that ignoring the contribution of the interfering γ-rays to the areas of the analytical peaks at 860.6 keV of (208)Tl, 338.3 and 911.2 keV of (228)Ac does not lead to any significant systematic influence on the (232)Th analysis. Because these factors are remained generally less than â¼5%, i.e., within overall uncertainty limits. The present study also showed that in view of both the spectral interference and TCS effects, the "cleaner" analytical peaks are seen at 338.3 keV (11.25%) and 911.2 keV (26.13%) of (228)Ac when high resolution γ-rays spectrometry was used in the (232)Th activity measurements. Therefore, they can be adopted as the "reference" peaks in the (232)Th analysis.
Assuntos
Artefatos , Radioisótopos/análise , Espectrometria gama/métodos , Tório/análise , Urânio/análise , Algoritmos , Raios gama , Doses de Radiação , Radioisótopos/química , Padrões de Referência , Tório/química , Urânio/químicaRESUMO
Primary squamous cell carcinoma (SCC) of the thyroid gland is a rare diagnosis, since there is no squamous epithelium in the thyroid gland. SCC of the thyroid is highly aggressive with a poor prognosis. We present a case of primary SCC of the thyroid: this 88-year-old male patient had a history of hyperthyroidism which was treated with radioactive iodine 25 years earlier. Whether this treatment could be related to SCC of the thyroid is not clear. We treated our patient with thyroidectomy and subsequent intensified radiotherapy. Six months after treatment our patient is doing well and there is no sign of local reoccurrence. Our work-up is described, including the differentiation from metastatic disease. The origin of squamous cell carcinoma in the thyroid is uncertain; we discuss some theoretical considerations. We conclude that after excluding metastatic disease, thyroidectomy combined with radiotherapy is the treatment of choice.
Assuntos
Carcinoma de Células Escamosas/etiologia , Radioisótopos do Iodo/efeitos adversos , Neoplasias Induzidas por Radiação/etiologia , Neoplasias da Glândula Tireoide/etiologia , Idoso de 80 Anos ou mais , Humanos , Hipotireoidismo/radioterapia , Radioisótopos do Iodo/uso terapêutico , MasculinoRESUMO
In this study, true coincidence-summing (TCS) correction factors have been measured for the sources (22)Na, (60)Co, (133)Ba and (152)Eu by use of three large volume coplanar grid CdZnTe (acronym: CZT) detectors. In case of a close-in detection geometry, two different TCS calculation algorithms were used to compute the required TCS correction factors. Both of the algorithms are based on the measured total-to-peak (TTP) ratio and full-energy peak (FEP) efficiency values that were obtained using almost "single" energy and coincidence-free nuclides. The results for TCS correction factors obtained by two different algorithms were agreeable to each other. The obtained TCS factors were ranged from about 7% to 30.5% in a 2250 mm(3) CZT detector when a close counting geometry was used. For other two detectors with a volume of 1000 and 1687.5mm(3), the resulted TCS correction factors were relatively smaller and varied between about 0.1% and 20% at the close counting geometry condition. Therefore, the results indicate that there is a need for the estimation of TCS corrections in CZT detectors, especially when their crystal volumes are greater than 1cm(3) and these detectors are used in the case of a close-in detection geometry.
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Alagille syndrome is largely unknown to the general internist because the diagnosis is usually made by a paediatrician. Nevertheless, it is important to be aware of this syndrome because it sometimes manifests later in life with a great variability in clinical presentation and important consequences for the individual patient. We therefore discuss this syndrome using a patient with the usual characteristics of this syndrome.
Assuntos
Síndrome de Alagille/diagnóstico , Rim/anormalidades , Insuficiência Renal/etiologia , Adulto , Aorta Abdominal/patologia , Colestase , Feminino , Doenças Genéticas Inatas , Humanos , Rim/patologia , Transplante de Rim , Linhagem , Estenose da Valva Pulmonar , Artéria Renal/patologia , Insuficiência Renal/cirurgiaRESUMO
BACKGROUND: Universal neonatal hearing screening programmes are encouraged to define and manage hearing loss in early ages of life. The aim of this study is to introduce our 14-month three-step hearing screening programme results with 16 975 births in Turkey. METHODS: In healthy neonates, Transient Evoked Otoacoustic Emission (TEOAE) is served as the initial screening in the first day of life. In newborns that did not meet pass criteria TEOAE was repeated in 10-day period. If the second test was 'refer' again, the screening was completed with auditory brainstem response (ABR). Additionally, ABR was performed for the neonates with neonatal intensive care unit (NICU) requirement and at high audiologic risk. Neonates who failed the screening test with ABR were referred for further evaluation. RESULTS: A total of 15 323 newborns and 1652 NICU infants were tested. The screening coverage was 94.4%; 14 521 neonates (94.7%) passed the first screening step (TEOAE), while 802 (5.2%) neonate failed. In total, 322 (40.1%) of the neonates out of 802 was subjected to the second TEOAE after 10 days have failed and ABR was applied. From the neonates participated the third step (ABR) totalling 1974, 43 (2.17%) of neonates obtained a 'refer' response. Out of these 43 neonates, 17 neonates were (39.5%) NICU infants. From the 43 neonates, 38 cases (88.4%) were found to have hearing impairment. The false-positive rate for first step screening with TEOAE was 4.9%; second step with TEOAE was 1.85% and for ABR was 0.25%. CONCLUSIONS: It is apparent that three step national hearing screening programme which has been applied for the latest years in Turkey is an accurate and non-invasive method to determine the congenital hearing loss. In the future, screening programmes could be rearranged with two steps as initial with TEOAE and retest with ABR and the coverage of the screening programme can be extended.
Assuntos
Transtornos da Audição , Triagem Neonatal/normas , Audição/fisiologia , Transtornos da Audição/congênito , Transtornos da Audição/diagnóstico , Transtornos da Audição/epidemiologia , Testes Auditivos/normas , Humanos , Lactente , Recém-Nascido , Programas de Rastreamento/normas , Triagem Neonatal/métodos , Emissões Otoacústicas Espontâneas , Fatores de Risco , Turquia/epidemiologiaRESUMO
When the high-resolution gamma-ray spectrometry was used in the analysis of (234)U and (230)Th in samples, there is a much more need to correct for the measured activity results of (234)U and (230)Th mainly due to self-absorption effects and the interfering lines from (226)Ra, (235)U, (238)U and their decay products that often might be present in the samples. Therefore, in the present study, the methods for the spectral interference corrections for the analytical peaks of (234)U and (230)Th are suggested to take into account the contributions of the overlapping gamma rays to these peaks. For the method validation, direct gamma-ray spectrometric measurements were carried out using certified reference materials (CRM) by use of a 76.5 % n-type Ge detector. The activities measured for the CRM samples were corrected for spectral interferences, self-absorption and true coincidence-summing (TCS) effects. The obtained results indicate that ignoring of the contribution of the interference gamma rays to the main analytical peak at 53.2 keV of (234)U leads to a lager systematic error of 87.3-90.4 % for the measured activities of (234)U, and similarly if one ignores the contributions of the interference gamma rays to the main analytical peak at 67.7 keV of (230)Th, this leads to a much smaller systematic error of 2.1-2.7 % for the activities of (230)Th. Therefore, the required correction factors for spectral interferences to the analytical peaks of (234)U and (230)Th are not negligible and thus they should also be considered besides necessary self-absorption factors to determine more accurate activities in the samples. On the other hand, it is estimated that although the TCS effects on the main analytical peaks of both (234)U and (230)Th are negligibly small, those TCS correction factors for their interference gamma rays to these peaks should be taken into account when direct measurements are performed in a close-counting geometry condition. Otherwise, the resulted activities can have serious erroneous results for both (234)U and (230)Th while using gamma-ray spectrometry, thereby leading to inaccuracies in their derived quantities, for instance, the corresponding age determinations of the samples.
Assuntos
Artefatos , Espectrometria gama/métodos , Tório/análise , Urânio/análise , Algoritmos , Humanos , Doses de Radiação , Padrões de ReferênciaRESUMO
In this study, the spectral interferences are investigated for the analytical peaks at 63.3 keV of (234)Th and 1001.0 keV of (234m)Pa, which are often used in the measurement of (238)U activity by the gamma-ray spectrometry. The correction methods are suggested to estimate the net peak areas of the gamma-rays overlapping the analytical peaks, due to the contribution of (232)Th that may not be negligible in materials rich in natural thorium. The activity results for the certified reference materials (CRMs) containing U and Th were measured with a well type Ge detector. The self-absorption and true coincidence-summing (TCS) effects were also taken into account in the measurements. It is found that ignoring the contributions of the interference gamma-rays of (232)Th and (235)U to the mixed peak at 63.3 keV of (234)Th ((238)U) leads to the remarkably large systematic influence of 0.8-122% in the measured (238)U activity, but in case of ignoring the contribution of (232)Th via the interference gamma-ray at 1000.7 keV of (228)Ac to the mixed peak at 1001 keV of (234m)Pa ((238)U) results in relatively smaller systematic influence of 0.05-3%, depending on thorium contents in the samples. The present results showed that the necessary correction for the spectral interferences besides self-absorption and TCS effects is also very important to obtain more accurate (238)U activity results. Additionally, if one ignores the contribution of (232)Th to both (238)U and (40)K activities in materials, the maximum systematic influence on the effective radiation dose is estimated to be ~6% and ~1% via the analytical peaks at 63.3 and 1001 keV for measurement of the (238)U activity, respectively.
Assuntos
Algoritmos , Artefatos , Espectrometria gama/métodos , Tório/análise , Tório/química , Urânio/análise , Urânio/química , Doses de RadiaçãoRESUMO
In this paper, the known multigroup gamma-ray analysis method for uranium (MGAU) as one of the non-destructive gamma-ray spectrometry methods has been applied to certified reference nuclear materials (depleted, natural and enriched uranium) containing (235)U isotope in the range of 0.32-4.51% atom (235)U. Its analysis gives incorrect results for the low component (235)U in depleted and natural uranium samples where the build-up of the decay products begins to interfere with the analysis. The results reveal that the build-up of decay products seems to be significant and thus the algorithms for the presence of decay products should be improved to resulting in the correct enrichment value. For instance, for the case of (235)U analysis in depleted uranium or natural ore samples, self-induced X-rays such as 94.6 keV and 98.4 keV lying in UXK(alpha) spectral region used by MGAU can be excluded from the calculation. Because the significant increases have been observed in the intensities of uranium self-induced X-rays due to gamma-ray emissions with above 100 keV energy arising from decay products of (238)U and (235)U and these parents. Instead, the use of calibration curve to be made between the intensity ratios of self-fluorescence X-rays to 92(*)keV gamma-ray and the certified (235)U abundances is suggested for the determination of (235)U when higher amounts of decay products are detected in the gamma-ray spectrum acquired for the MGAU analysis.
Assuntos
Espectrometria gama/métodos , Urânio/análise , Fluorescência , Raios gama , Raios XRESUMO
Sugar syrup decolorization was studied using two commercial and eight beet pulp based activated carbons. In an attempt to relate decolorizing performances to other characteristics, surface areas, pore volumes, bulk densities and ash contents of the carbons in the powdered form; pH and electrical conductivities of their suspensions and their color adsorption properties from iodine and molasses solution were determined. The color removal capabilities of all carbons were measured at 1/100 (w/w) dosage, and isotherms were determined on better samples. The two commercial activated carbons showed different decolorization efficiencies; which could be related to their physical and chemical properties. The decolorization efficiency of beet pulp carbon prepared at 750 degrees C and activated for 5h using CO2 was much better than the others and close to the better one of the commercial activated carbons used. It is evident that beet pulp is an inexpensive potential precursor for activated carbons for use in sugar refining.