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1.
Sci Rep ; 11(1): 21398, 2021 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-34725365

RESUMO

Our study evaluated the association between Demodex infestation and recurrent hordeola and examined the clinical features associated with these eyelid lesions. This was an observational, comparative study. We reviewed 250 patients and divided them into the recurrent hordeolum (n = 153) and control (n = 97) groups. Demodex infestation was detected by epilating eyelashes around the lesion/s and viewing them under a light microscope. Patient medical records and photographs were retrospectively analyzed to identify the clinical characteristics of Demodex-associated recurrent hordeola. Demodex was detected in 91 (59.5%) and 17 (17.5%) patients in the recurrent hordeolum and control groups (p < 0.001), respectively. In the recurrent hordeolum group, Demodex mites were found in 74 (68.5%) and 17 (37.8%) of the adult and pediatric patients (p < 0.001), respectively. Among patients with recurrent hordeola, patients in their 20s were most likely to have concomitant Demodex infestation. Patients with Demodex infestations were also more likely to develop recurrent lesions within a shorter period of time from the primary incision and curettage. The most common presentation of Demodex-associated recurrent lesions was external hordeola (67%) (p = 0.002). Demodex infestation may cause recurrent hordeola in adults and children. These mites may play a greater role in the development of lesions in adult patients. The strongest association between Demodex infestation and recurrent lesions was seen in patients in their 20s. Our results suggest that if the hordeola recur within a short period of time with the clinical characteristics of external location of eyelid, multiple numbers of lesions, or anterior blepharitis, eyelash epilation should be performed to identify the presence of Demodex mites.

2.
Artigo em Inglês | MEDLINE | ID: mdl-34648155

RESUMO

This experimental study analyzed the use of solar photovoltaic energy for operating a novel twin-circuit DC milk chiller without batteries using water-based cold thermal energy storage for different seasons in Chennai, India. HFC-134a and HC-600a were used as refrigerants in the two individual circuits. For each season, the test was conducted continuously for 18 days to analyze the quantity of generated ice that could be utilized to chill 10 L of milk in the morning and in the evening. The average quantity of ice formed per day in the ice bank during monsoon, winter, and summer seasons was found to be 3.61, 19.75, and 27.97 kg, respectively. Thus, it is evident that the use of solar energy with thermal energy storage is effective for operating the milk chilling unit for two seasons, namely winter and summer. However, the system requires an additional power source for continuous operation during the monsoon season. It is noteworthy to mention that the use of a solar milk chiller instead of a conventional milk chiller resulted in 91.15% lesser CO2 emission with 27.6% less LCC. In this study, solar photovoltaic power was observed to be a good choice for chilling milk in the context of global warming and energy consumption. The use of thermal energy storage also allows the initial cost to be reduced.

3.
Artigo em Inglês | MEDLINE | ID: mdl-34491501

RESUMO

This research article discusses properties such as density, thermal conductivity, and electrical conductivity of solar glycol with amine-functionalized graphene and multi-walled carbon nanotubes (MWCNTs). The hybrid nanofluid is prepared by dispersing the amine-functionalized graphene (AFG) and MWCNTs (50:50 in % by weight ratio) in pure solar glycol. The AFG and MWCNTs are dispersed in different volume concentrations of 0.05%, 0.1%, and 0.15% through the classical two-step homogenizing technique. Good colloidal stability nanofluid are prepared with Gum Arabic (non-covalent) as the surfactant. The stability of nanofluids is ensured through scanning electron microscopy, UV-Vis spectrometer, and zeta potential analyzer. The nanofluid thermal conductivity is measured with varying the nanomaterial loading from 0.05 to 0.15 vol% using a KD2 pro thermal analyzer. The thermal conductivity and electrical conductivity of nanofluid augmentations are considerably with an increasing volume concentration of AFG and MWCNT loading. The thermal conductivity of the AFG-MWCNT-based hybrid nanofluid is augmented by 8.59% for the maximum concentration of 0.15 vol% at 50 °C. The electrical conductivity of the solar glycol-based nanofluids is enhanced linearly with increased operating temperatures. The maximum electrical conductivity enhancement attained is ~28.85% at a nanoparticle loading of 0.15 vol% and 70 °C.

4.
Artigo em Inglês | MEDLINE | ID: mdl-34528193

RESUMO

This work aims to develop a novel nanofluid using Therminol-55 (T-55) as heat transfer fluid and multi-wall carbon nanotubes (MWCNTs) as dispersants with various volume concentrations of 0.05, 0.1, 0.3, and 0.5% and assess its thermo-physical properties for solar-thermal applications. The pH values of nanofluid MWCNT/T-55 with various particle loading were too far-flung from the pH (I) value, which confirmed the good dispersion stability of nanofluid. The measured density shows tremendous deviation from predicted density with increasing MWCNT loading owing to the non-considering of microstructural parameters in Pak & Cho correlation predication. The highest augmentation in nanofluid thermal conductivity was 16.83% for 0.5 vol. % MWCNT at 60 °C. The maximum improvement in dynamic viscosity of nanofluid with 0.5 vol. % of MWCNT is found to be 44%, and this rise is reduced at higher temperatures. The thermal effectiveness of the nanofluids demonstrates that nanofluid with all volume fractions of MWCNTs was favorable at higher temperatures in the laminar region. Mouromtseff number ratio decreases with a rise in temperature and MWCNT volume concentration. It is concluded that the excellent thermo-physical properties and prolonged thermal stability of the MWCNT will be highly beneficial in improving the overall performance of various kinds of heat transfer fluids (HTFs) for process heating and solar-thermal applications.

5.
Artigo em Inglês | MEDLINE | ID: mdl-34585351

RESUMO

This work aims to explore the optical and thermal conversion characteristics of activated carbon-solar glycol nanofluids with various volume fractions namely 0.2, 0.4, and 0.6%, respectively. Kigelia africana leaves were synthesized into porous activated carbon nanomaterials by using the high-temperature sintering process and the pyrolysis process in a muffle furnace. The experimental investigation was carried out with different nanofluid concentrations by using the solar simulator. Nanofluids were heated with the assistance of a solar simulator test system and the convection/conduction heat loss was decreased by using the glass as an insulating material around the test section. Prepared nanofluid with 0.6 vol% activated carbon augmented the thermal conductivity by 14.36% at 60°C. The maximum temperature difference of 10°C was attained at 0.6% volume concentrations of nanofluid as compared with base fluid (solar glycol). In addition, maximum receiver efficiency of 94.51% was attained at 0.6% volume fractions of activated carbon-based nanofluid compared with solar glycol thru a light radiation time of 600 s. Moreover, activated carbon-based nanofluid exhibited significantly higher absorption efficiency as the majority of the radiation was absorbed by the nanofluid. It is concluded that activated carbon-based nanofluids could be a suitable low-cost highly stable material for developing working fluid for direct absorbance solar collector-based applications.

6.
Materials (Basel) ; 14(11)2021 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-34205219

RESUMO

Heavy metal pollution in the environment is a critical issue, engendering ecosystem deterioration and adverse effects on human health. The main objective of this study was to evaluate heavy metal adsorbents by modifying industrial byproducts. The bottom ash was sintered and evaluated for Cd and Pb sorption. Three adsorbents (bottom ash, sintered bottom ash (SBA), and SBA mixed with microorganisms (SBMA)) were tested to evaluate the sorption kinetics and mechanism using a lab-scale batch experiment. The results showed that the highest sorption efficiency was observed for Cd (98.16%) and Pb (98.41%) with 10% SBA. The pseudo-second-order kinetic model (R2 > 0.99) represented the sorption kinetics better than the pseudo-first-order kinetic model for the SBA and SBMA, indicating that chemical precipitation could be the dominant sorption mechanism. This result is supported by X-ray photoelectron spectroscopy analysis, demonstrating that -OH, -CO3, -O, and -S complexation was formed at the surface of the sintered materials as Cd(OH)2 and CdCO3 for Cd and PbO, and PbS for Pb. Overall, SBA could be utilized for heavy metal sorption. Further research is necessary to enhance the sorption capacity and longevity of modified industrial byproducts.

7.
J Hazard Mater ; 419: 126470, 2021 10 05.
Artigo em Inglês | MEDLINE | ID: mdl-34216960

RESUMO

Biological desulfurization processes of landfill gas yield an enormous amount of biologically produced S (BPS) as a byproduct. Capability of BPS to remove Cd2+ from aqueous solutions was tested and its removal efficiency was compared to that of granular activated carbon (GAC). Kinetics of Cd2+ removal by BPS was a two-stage process with an initial rapid adsorption showing 45% of initial Cd2+ was removed within 5 min, followed by a slower adsorption. Cadmium adsorption onto the BPS fitted the Langmuir isotherm model and maximum adsorption capacity of the BPS (63.3 mg g-1) was 1.8 times higher than that of GAC (36.1 mg g-1). Thermodynamic parameters showed that Cd2+ adsorption by BPS was favorable and endothermic. Data from XPS proved the main adsorption mechanism to be complexation of Cd2+ with sulfides in the BPS. Results demonstrated that BPS can be recycled as a novel adsorbent for Cd2+ removal from wastewater.


Assuntos
Cádmio , Poluentes Químicos da Água , Adsorção , Cádmio/análise , Carvão Vegetal , Concentração de Íons de Hidrogênio , Cinética , Soluções , Enxofre , Termodinâmica , Poluentes Químicos da Água/análise
8.
Korean J Ophthalmol ; 35(3): 231-234, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-34120422

RESUMO

PURPOSE: Silicone tube intubation is the most common method for treatment of nasolacrimal drainage disorder or repair of lacerated canaliculus. However, some cases are prolapsed earlier than expected, subsequently affecting the success rate of silicone tube intubation. The author introduced a successful reposition of the prolapsed silicone tube. METHODS: This study is a retrospective case series of 11 patients who were treated with reposition of prolapsed silicone tube using hole and lacrimal probe method. In all cases, the tubes were prolapsed within 2 months after the first surgery due to careless rubbing of the medial canthus by the patient. In all 11 cases, the development of a biofilm on tube was not observed at the time when the tube was prolapsed. All patients underwent immediate reposition of prolapsed tube without local anesthesia in the outpatient operating room on the day they visited. RESULTS: In all 11 cases, the prolapsed silicone tube was repositioned without any complications using this hole and lacrimal probe method. At 6-month follow-up examination, all patients presented with a well-positioned silicone tube up to the day of extubation without replacing it with a new silicone tube. CONCLUSIONS: This hole and lacrimal probe method is effective for the repositioning of prolapsed silicone tube after bicanalicular intubation of lacrimal system. This procedure includes easy performance in a short time and without local anesthesia in the outpatient operating room.


Assuntos
Dacriocistorinostomia , Aparelho Lacrimal , Obstrução dos Ductos Lacrimais , Ducto Nasolacrimal , Humanos , Obstrução dos Ductos Lacrimais/terapia , Ducto Nasolacrimal/cirurgia , Estudos Retrospectivos , Elastômeros de Silicone , Silicones
9.
Saf Health Work ; 11(4): 405-417, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33329906

RESUMO

Background: Electrical socket outlets are used continuously until a failure occurs because they have no indication of manufacturing date or exchange specifications. For this reason, 659 electrical fires related to electrical socket outlets broke out in the Republic of Korea at 2018 only, an increase year on year. To reduce electrical fires from electrical socket outlets, it is necessary to perform an accelerated test and analyze the thermal, insulation resistance, and material properties of electrical socket outlets by installation years. Methods: Thermal characteristics were investigated by measured the temperature increase of electrical socket outlets classified according to year with variation of the current level. Insulation resistance characteristics was measured according to temperature for an electrical socket outlets by their years of use. Finally, to investigate the thermal and insulation resistance characteristics in relation to outlet aging, this study analyzed electrical socket outlets' conductor surface and content, insulator weight, and thermal deformation temperature. Results: Analysis showed, regarding the thermal characteristics, that electrical socket outlet temperature rose when the current value increased. Moreover, the longer the time that had elapsed since an accelerated test and installation, the higher the electrical socket outlet temperature was. With respect to the insulation resistance properties, the accelerated test (30 years) showed that insulation resistance decreased from 110 °C. In relation to the installation year (30 years), insulation resistance decreased from 70 °C, which is as much as 40 °C lower than the result found by the accelerated test. Regarding the material properties, the longer the elapsed time since installation, the rougher the surface of conductor contact point was, and cracks increased. Conclusion: The 30-year-old electrical socket outlet exceeded the allowable temperature which is 65 °C of the electrical contacts at 10 A, and the insulation resistance began to decrease at 70 °C. It is necessary to manage electrical socket outlets that have been installed for a long time.

11.
Molecules ; 24(14)2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31311184

RESUMO

Herein, contaminants remaining in distillate and distillers' stillage were quantitatively measured after distillation. After rice bran powder was contaminated with 10 ppm of lead (Pb) and cadmium (Cd) or 0.02-1.27 ppm of five pesticides (terbufos, fenthion, iprobenfos, flutolanil, and ethoprophos) followed by fermentation, single-stage distillation was performed. In the obtained distillate, no Pb or Cd was found, as expected. However, when the pesticides were added as contaminants, trace-0.05 ppm of some pesticides were detected in the distillate, possibly due to the high vapor pressure (e.g., that of ethoprophos) and contamination amount (e.g., that of flutolanil, terbufos, and fenthion). In contrast, none of the contaminating pesticides were observed in the distilled spirits when a fermented liquefaction contaminated with 0.04-4 ppm of six pesticides (fenthion, terbufos, ethoprophos, iprobenfos, oxadiazon, and flutolanil) was distilled using a pilot-plant scale distillation column, indicating that the pesticides hardly migrate to the distilled spirits.


Assuntos
Bebidas Alcoólicas/análise , Contaminação de Alimentos/análise , Oryza/química , Resíduos de Praguicidas/análise , Anilidas/análise , Cádmio/análise , Destilação , Fention/análise , Fermentação , Chumbo/análise , Compostos Organotiofosforados/análise , Projetos Piloto
12.
SAGE Open Med Case Rep ; 7: 2050313X18823415, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30719306

RESUMO

Cyanoacrylate ablation, along with mechanochemical ablation, is one of the best-known non-thermal ablation treatment methods for superficial venous reflux. Cyanoacrylate ablation is comparable to thermal ablation in terms of efficacy and safety, and offers the benefit of not requiring tumescent injections and the use of compression stockings. Here, we report about a patient who developed recurrent reflux in the residual stump after cyanoacrylate ablation. As a refluxing long residual stump can be a risk factor for late recurrence, improvements are needed to make the protocol more refined, including leaving the stump as short as possible.

13.
ACS Appl Mater Interfaces ; 10(39): 33112-33123, 2018 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-30192505

RESUMO

The chemical environments of the interlayer Na sites of layered titanate are finely controlled by the intercalation of n-alkylamine with various alkyl chain lengths to explore an effective way to improve its electrode functionality for sodium-ion batteries (SIBs). The n-alkylamine intercalation via ion-exchange and exfoliation-restacking routes allows the modification of in-plane structures of layered titanate to be tuned. Among the present n-alkylamine-intercalates, the n-pentylamine-intercalated titanate shows the largest discharge capacity with the best rate characteristics, underscoring the critical role of optimized intracrystalline structure in improving the SIB electrode performance of layered titanate. The creation of turbostratic in-plane structure degrades the SIB electrode performance of layered titanate, indicating the detrimental effect of in-plane structural disorder on electrode activity. 23Na magic-angle spinning nuclear magnetic resonance spectroscopy demonstrates that the n-alkylamine-intercalated titanates possess two different interlayer Na+ sites near ammonium head groups/titanate layers and near alkyl chains. The intercalation of long-chain molecules increases the population of the latter site and the overall mobility of Na+ ions, which is responsible for the improvement of electrode activity upon n-alkylamine intercalation. The present study highlights that the increased population of interlayer metal sites remote from the host layers is effective in improving the electrode functionality of layered metal oxide for SIBs and multivalent ion batteries.

14.
Ophthalmic Plast Reconstr Surg ; 34(4): e121-e123, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29923967

RESUMO

Kimura disease has been known as a chronic inflammatory disease of unknown etiology, since the first report in 1937 and characterized by an increased eosinophil fraction in peripheral blood, increased serum immunoglobulin E (IgE) levels, and lymphoid granuloma with eosinophilic infiltration on histopathological examination. The authors present a 30-year-old man who visited their clinic with a 3-month history of protrusion and conjunctival injection of the right eye. Surgical mass resection was performed, and initial histopathology revealed Kimura disease. Additional immunohistochemical examination revealed IgG4-related disease in another hospital, which showed more than 80 IgG4-positive plasma cells per high-power field and an IgG4+/IgG+ ratio more than 40%. There are histopathological similarities, and several reports have suggested a relationship between Kimura disease and IgG4-related disease. Thus, it is difficult to classify them as completely different diseases. Kimura disease and IgG4 can be considered a part of a clinical spectrum of abnormal immune reactions.


Assuntos
Hiperplasia Angiolinfoide com Eosinofilia/diagnóstico , Imunoglobulina G/sangue , Doenças Orbitárias/diagnóstico , Adulto , Humanos , Masculino
15.
Mitochondrial DNA B Resour ; 3(2): 570-571, 2018 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-33474245

RESUMO

Here, we report the complete mitogenome of Myotis frater with the GenBank accession number MH177276 as a first step to elucidate genetic characteristics of this species. Its mitogenome was 17,089 bp long and consisted of 13 protein-coding genes (PCGs), two rRNA genes, 22 tRNA genes, and a control region. The gene order and composition of M. frater was similar to that of most other vertebrates. The base composition of the 13 PCG in descending order was A (33.8%), C (22.7%), T (30.4%), and G (13.1%), with an AT content of 64.2%. Four overlapping regions in ATP8/ATP6, ATP6/COX3, ND4L/ND4, and ND5/ND6, among the 13 PCGs were found. The 935 bp long control region is located between tRNA-Pro and tRNA-Phe with 4 ATTACATAATACATTATATGTATAATCGTACATTAAATTAACTCCCACATGAATATTAAGCATGTCCATACTAATATTAAT-repeat at 5' region and 45 ACGCAT-repeat at 3' terminus. Phylogenetic analysis suggested that M. frater is most closely related to M. bechsteinii (KX757757), it was supported by 100% bootstrap under both ML and NJ tree.

16.
J Craniomaxillofac Surg ; 45(10): 1687-1691, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28847622

RESUMO

OBJECTIVE: To compare the effectiveness of the Quickert suture (Q-suture) with that of the lateral tarsoligamentous sling in treating lower eyelid involutional entropion in Asians. METHOD: We reviewed the charts of all patients who underwent repair of an involutional lower eyelid entropion in Hangil Eye Hospital between September 2011 and March 2016. A single surgeon (S. C. Kim) performed the procedure in every case. Patients underwent either Q-suturing or lateral tarsoligamentous sling. We analyzed the results using Mann-Whitney and Chi-square tests, as well as Kaplan-Meier survival analysis. A p-value of <0.05 was considered to indicate significance. RESULTS: A total of 50 patients (61 eyes) were included in the study. Of the 50 patients, 24 (30 eyelids) received Q-suture and 26 patients (31 eyelids) underwent lateral tarsoligamentous sling. In all patients who underwent lateral tarsoligamentous sling, the entropion was successfully corrected and did not recur. Furthermore, none of the patients experienced any significant postoperative complications. In contrast, entropion recurred in 16 (36.67%) of the patients who underwent Q-suture (mean of 10.88 ± 9.02 months after surgery). The recurrence rate was not significantly correlated with age (p = 0.093); it was higher in men than in women, although this was not a significant difference (46.67% vs 26.6.7%; p = 0.175 by Chi-squared test). Kaplan-Meier survival analysis showed that the recurrence rate after Q-suture differed significantly from that after lateral tarsoligamentous sling (36.67% vs 0%, respectively; p = 0.007). CONCLUSION: This study suggests that lateral tarsoligamentous sling is an effective surgical method for correcting lower eyelid involutional entropion; the technique is not associated with recurrence or significant complications in Asians.


Assuntos
Entrópio/cirurgia , Técnicas de Sutura , Idoso , Idoso de 80 Anos ou mais , Grupo com Ancestrais do Continente Asiático , Humanos , Pessoa de Meia-Idade , Estudos Retrospectivos , Resultado do Tratamento
17.
Environ Geochem Health ; 39(2): 345-352, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28213721

RESUMO

Remediation of potentially toxic trace elements (PTEs) in paddy fields is fundamental for crop safety. In situ application of chemical amendments has been widely adapted because of its cost-effectiveness and environmental safety. The main purpose of this research was to (1) evaluate the reduction in dissolved concentrations of cadmium (Cd) and arsenic (As) with the application of chemical amendments and (2) monitor microbial activity in the soil to determine the remediation efficiency. Three different chemical amendments, lime stone, steel slag, and acid mine drainage sludge, were applied to paddy fields, and rice (Oryza sativa L. Milyang 23) was cultivated. The application of chemical amendments immobilized both Cd and As in soil. Between the two PTEs, As reduction was significant (p < 0.05) with the addition of chemical amendments, whereas no significant reduction was observed for Cd than that for the control. Among six soil-related variables, PTE concentration showed a negative correlation with soil pH (r = -0.70 for As and r = -0.54 for Cd) and soil respiration (SR) (r = -0.88 for As and r = -0.45 for Cd). This result indicated that immobilization of PTEs in soil is dependent on soil pH and reduces PTE toxicity. Overall, the application of chemical amendments could be utilized for decreasing PTE (As and Cd) bioavailability and increasing microbial activity in the soil.


Assuntos
Arsênio/farmacocinética , Cádmio/farmacocinética , Recuperação e Remediação Ambiental/métodos , Microbiologia do Solo , Poluentes do Solo/farmacocinética , Arsênio/análise , Disponibilidade Biológica , Biomassa , Cádmio/análise , Carbonato de Cálcio , Oryza , Melhoria de Qualidade , República da Coreia , Esgotos , Solo/química , Poluentes do Solo/análise
18.
J Comput Assist Tomogr ; 41(2): 236-241, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-27680420

RESUMO

OBJECTIVE: This study examined the effect of coronary artery calcification score by lifestyle and correlation with coronary artery stenosis in persons who underwent coronary artery computed tomography (CT) angiography among health examinees for heart diseases in Korea. METHODS AND MATERIALS: The study included 506 subjects (256 men and 250 women) who underwent coronary artery CT angiography among health examines for heart diseases at the Incheon Branch of the Korea Association of Health Promotion between January 2, 2014, and December 31, 2014. The demographical variables of the subjects were determined by frequency analysis, and the difference by sex was compared and analyzed using χ independence test. Independent 2-sample t test was performed to determine any difference in main factors by coronary artery calcification. RESULTS: According to the results, 175 (34.6%) had calcification, men showed statistically higher scores than women, and calcification seemed higher in those who were older, taller, heavier, and thicker in waist. Regarding blood pressure, calcification was shown if contraction phase and relaxation blood pressure was higher, blood sugar before meal was higher, and neutral fat was higher. By lifestyle, calcification seemed to be higher in those with more alcohol drinking per week, long past smoking years, and higher smoking amount per day in the past and present. In addition, coronary artery stenosis rate showed statistical correlation with calcification from the left anterior descending artery, right coronary artery, left circumflex artery, and left main coronary artery in sequence. CONCLUSIONS: In conclusion, coronary artery calcification score CT is deemed to be a suitable method for the estimation of coronary artery stenosis with short examination time, low radiation exposure, and noninvasive method.


Assuntos
Calcinose/diagnóstico por imagem , Angiografia por Tomografia Computadorizada/métodos , Angiografia Coronária/métodos , Estenose Coronária/diagnóstico por imagem , Estilo de Vida , Tomografia Computadorizada Multidetectores/métodos , Fatores Etários , Composição Corporal , Vasos Coronários/diagnóstico por imagem , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , República da Coreia , Fatores de Risco , Fatores Sexuais
19.
Inorg Chem ; 55(17): 8359-70, 2016 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-27494550

RESUMO

Eu(2+)-activated M5(PO4)3X (M = Ca, Sr, Ba; X = F, Cl, Br) compounds providing different alkaline-earth metal and halide ions were successfully synthesized and characterized. The emission peak maxima of the M5(PO4)3Cl:Eu(2+) (M = Ca, Sr, Ba) compounds were blue-shifted from Ca to Ba (454 nm for Ca, 444 nm for Sr, and 434 nm for Ba), and those of the Sr5(PO4)3X:Eu(2+) (X = F, Cl, Br) compounds were red-shifted along the series of halides, F → Cl → Br (437 nm for F, 444 nm for Cl, and 448 nm for Br). The site selectivity and occupancy of the activator ions (Eu(2+)) in the M5(PO4)3X:Eu(2+) (M = Ca, Sr, Ba; X = F, Cl, Br) crystal lattices were estimated based on theoretical calculation of the 5d → 4f transition energies of Eu(2+) using LCAO. In combination with the photoluminescence measurements and theoretical calculation, it was elucidated that the Eu(2+) ions preferably enter the fully oxygen-coordinated sites in the M5(PO4)3X:Eu(2+) (M = Ca, Sr, Ba; X = F, Cl, Br) compounds. This trend can be well explained by "Pauling's rules". These compounds may provide a platform for modeling a new phosphor and application in the solid-state lighting field.

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