Browsing by Author "Kucuk N."
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Item Doping Sm3+ into ZnB2O4 phosphors and their structural and cathodoluminescence properties(Elsevier Ltd, 2018) Kucuk N.; Bulcar K.; Dogan T.; Garcia Guinea J.; Portakal Z.G.; Karabulut Y.; Ayvacikli M.; Canimoglu A.; Topaksu M.; Can N.In this study, ZnB2O4:xSm3+ (0.01 ≤ x ≤ 0.05 mol) powder phosphors have been synthesized by low temperature chemical synthesis method. The structure and morphological observation of the phosphor samples were systematically monitored by X-ray powder diffraction (XRD) and environmental scanning electron microscope (ESEM) coupled to an energy dispersive X-ray spectrometer (EDS). The all diffraction peaks are well assigned to standard data card (PDF#39-1126). Emission properties of the samples were explored using light emission induced by an electron beam (i.e cathodoluminescence, CL) at room temperature (RT). When excited with electron beam, CL spectral measurements of scrutinized phosphors exhibit orange-red luminescence at 572 nm, 606 nm and 658 nm due to various transition from ground state to 6H5/2,6H7/2 and 4G5/2 states, respectively. The transition 4G5/2 → 6H7/2 located at 606 nm can occur as hypersensitive transition having the selection rule ΔJ = ±1. The observed peaks are in the region of yellow reddish light of Sm3+. Experimental results verify that the optimum Sm3+ content in terms of intense luminescence for this series of phosphors was 2%. Beyond 2% of Sm3+ ions concentration, luminescence quenching occurs due to an enhanced probability of the energy transfer from one Sm3+ to another that matches in energy via cross-relaxation and dipole-dipole interactions according to Dexter theory. A suitable energy transfer model between two adjacent Sm3+ ions in the ZnB2O4 phosphors was accomplished by the electric dipole-dipole interaction. The critical transfer distance (Rc) for non-radiative energy transfer was found to be 21.52 Å at 2 mol % Sm3+ doped ZnB2O4. Additionally, thermoluminescence (TL) glow curves of undoped and Sm activated ZnB2O4 under beta irradiation of 10 Gy are also discussed here. © 2018 Elsevier B.V.Item Thermoluminescence behavior of Sm3+ activated ZnB2O4 phosphors synthesized using low temperature chemical synthesis method(Elsevier B.V., 2018) Bulcar K.; Dogan T.; Akça S.; Yüksel M.; Ayvacikli M.; Karabulut Y.; Kucuk N.; Canimoglu A.; Can N.; Topaksu M.This study is mainly centered on thermoluminescence (TL) behavior under beta excitation at room temperature (RT) of Sm3+ activated ZnB2O4 phosphors synthesized by low temperature chemical synthesis method. The prepared phosphors were characterized by the X-ray powder diffraction (XRD) method. The effects of dopant concentration, beta radiation dose (0.115–69 Gy) and heating rate (0.5–10 °C/s) on TL intensity of Sm3+ doped ZnB2O4 phosphors and reproducibility are investigated using a lexsyg smart TL/OSL reader system. The activation energy values, E obtained from the analysis of the TL glow curve were calculated with initial rise (IR) method and peak shape (PS) method over the deconvoluted glow curves. The Ea–Tstop and CGCD methods indicated that the glow curve of this phosphor is the superposition of at least six components, which were called to as P1–P6, in the temperature range between RT and 400 °C. The results reveal that 2% Sm3+ doped ZnB2O4 gives optimum TL response, the relative intensity of the glow peak increases linearly with increase of beta dose and, the peaks of TL glow curves shift towards the higher temperature side with increase in heating rate as the total area under the glow peak remains the same. The maximum variation of reproducibility for ten successive irradiation cycles of 20.7 Gy is less than 3% from the average value and the sample doped 2% Sm3+ shows a good stability for the reusability. Additionally, the results obtained from IR and PS methods indicates that the complex glow curve is composed of six distinguishable peaks. © 2018 Elsevier B.V.Item Thermoluminescence dose and heating rate dependence and kinetic analysis of ZnB2O4:0.05Dy3+ phosphor(Elsevier B.V., 2018) Balci-Yegen S.; Yüksel M.; Kucuk N.; Karabulut Y.; Ayvacikli M.; Can N.; Topaksu M.The intention of this study is to explore the thermoluminescence (TL) behavior of beta irradiated 5% Dy3+ doped zinc borate (Zn(BO2)2:0.05Dy3+) phosphor prepared using the nitric acid method. The TL glow curve corresponding from 1 Gy to 80 Gy beta irradiation (preheated at 140 °C) shows a maxima at c.a. 180 °C. The dependence of heating rate was tested and found out that thermal quenching effect was dominating on TL glow curves as the heating rate increases. The dose response of the phosphor material exposed to beta radiation was investigated. Deconvolution was applied using the peak fit method on the glow curve for optimized conditions. Also peak shape (PS), various heating rates (VHR) and computerized glow curve deconvolution (CGCD) methods were used to evaluate the trapping level parameters, namely trap depth (E), frequency factor (s) and order of kinetics (b) associated with the main glow curve in Zn(BO2)2:0.05Dy3+ phosphor after beta irradiation of 20 Gy. The values of trap depth corresponding with the TL glow peak at 180 °C were found to be 0.93 eV, 0.92 ± 0.05 and 1.05 ± 0.02 respectively. Furthermore W and c parameters characterizing thermal quenching based on the Mott-Seitz theory were determined as 0.31 ± 0.04 eV and 162.55. The TL mechanism appears more likely to get second order kinetics, suggesting the probability of re-trapping of charge carriers by emptied traps. © 2017 Elsevier B.V.Item Cathodoluminescence and thermoluminescence of ZnB2O4:Eu3+ phosphors prepared via wet-chemical synthesis(Elsevier Ltd, 2019) Dogan T.; Tormo L.; Akca S.; Kucuk N.; Guinea J.G.; Karabulut Y.; Ayvacikli M.; Oglakci M.; Topaksu M.; Can N.In present work, a series of Eu doped zinc borate, ZnB2O4, phosphors prepared via wet chemical synthesis and their structural, surface morphology, cathodoluminescence (CL) and thermoluminescence (TL) properties have been studied. Phase purity and crystal structure of as-prepared samples are confirmed by X-ray diffraction measurements (XRD) and they were well consistent with PDF card No. 39-1126, indicating the formation of pure phase. The thermoluminescence (TL) behaviors of Eu activated ZnB2O4 host lattice are studied for various beta doses ranging from 0.1 to 10 Gy. The high-temperature peak of Eu activated sample located at 192 °C exhibited a linear dose response in the range of 0.1–10 Gy. Initial rise (IR) and peak shape (PS) methods were used to determine the activation energies of the trapping centres. The effects of the variable heating rate on TL behaviour of Eu activated ZnB2O4 were also studied. When excited using an electron beam induced light emission (i.e cathodoluminescence, CL) at room temperature (RT), the as-prepared phosphors generate reddish-orange color due to predominant emission peaks of Eu3+ ions located at 576–710 nm assigned to the 5D0→7FJ (J=1,2,3, and 4) transitions. The maximum CL intensity for Eu3+ ions at 614 nm with transition 5D0→7F2 was reached Eu3+ concentration of 5 mol%; quenching occurred at higher concentrations. Strong emission peak for Eu3+ ions at 614 nm with transition 5D0→7F2 is observed. The CL experimental data indicate that ZnB2O4:Eu3+ phosphor as an orange-red emitting phosphor may be promising luminescence materials for the optoelectronic applications. © 2018 Elsevier Ltd and Techna Group S.r.l.Item Thermoluminescence properties of Tb doped Mg2SiO4 after beta irradiation(Elsevier B.V., 2019) Akça S.; Portakal Z.G.; Dogan T.; Kucuk N.; Canimoglu A.; Topaksu M.; Can N.In this study, we performed Thermoluminescence (TL) experiments to extract the trapping parameters and dosimetric properties of Tb-doped Mg2SiO4 phosphors. Glow peaks located at 193, 270, and 350 °C were observed in the glow curve but the peak at 193 °C was especially investigated as a dosimetric peak in this study. We also observed an anomalous heating rate effect in which the maximum TL intensity of the glow curve augmented with an increasing heating rate. The computerized glow curve deconvolution (CGCD) method, initial rise (IR) and Hoogenstraaten's method were used to determine the activation energies of associated trapping centers for both BSL-TL 365 nm and IRSL-TL wideband blue filters. The TL characteristics of this phosphor indicate that Mg2SiO4:Tb3+ could be a promising material for dosimetric applications. Efforts should be made to improve the fading behaviour by adding other activators as co-dopants. © 2019 Elsevier B.V.Item Thermoluminescence spectra of Tm doped ZnB 2 O 4 phosphor prepared via a wet-chemical synthesis(Elsevier Ltd, 2019) Bulcar K.; Kucuk N.; Topaksu M.; Can N.In this paper we describe the thermoluminescence (TL) characteristics of 0.8 mol% Tm 3+ doped ZnB 2 O 4 phosphors prepared by a wet-chemical method. The TL glow curves of the phosphor sample consisted of three peaks located at 181 °C, 213 °C and 351 °C. The glow peak TL temperature (T m ) at which the TL glow peak occurs shifts toward the higher temperature side whilst the heating ramp rate increases and also the peak TL intensity (I m ) decreases. The TL glow curves are characterized by evaluating various dosimetric characteristics of scrutinized samples. The T m −T stop investigations on regenerated TL signals revealed that there are five different traps in the phosphor with energy values in the range of 0.61–1.71 eV. The dose responses increased in a linear way for 3 peaks with the beta-ray exposure in the dose range of 0.11–60 Gy. The process of applying 10 Gy dose was repeated for ten successive irradiation cycles to check reproducibility and the maximum variation was found to be less than 1% from the average value. These results provide valuable knowledge for use of the characteristics of T m doped ZnB 2 O 4 in dosimetry research. © 2019 Elsevier LtdItem Thermoluminescence analysis of beta irradiated ZnB 2 O 4 : Pr 3+ phosphors synthesized by a wet-chemical method(Elsevier Ltd, 2019) Akca S.; Oglakci M.; Portakal Z.G.; Kucuk N.; Bakr M.; Topaksu M.; Can N.In this paper we describe the thermoluminescence (TL) characteristics of ZnB 2 O 4 :Pr 3+ phosphors with Pr concentrations varying between 0.2 and 1 mol% prepared by a wet-chemical method. The TL glow curves of the phosphor sample consisted of three peaks located at 71 °C (P1), 124 °C (P2) and 233 °C (P3). The TL intensity increased with the beta dose ranging from ∼0.1 to ∼20 Gy. Dose response, reproducibility and trapping parameters of TL glow curves were evaluated to clearly reveal thermoluminescence features. We observed that TL intensity of P2 and P3 peaks decreases as the heating rate increases. Trap parameters were estimated via the Hoogenstraaten, Booth-Bohun-Parfianovitch, the initial rise methods combined with T m −T stop experiment and TLanal CGCD program. Heating rates were varied to use in the Hoogenstraaten analyses. The T m −T stop investigations on regenerated TL signals for P1 and P2 peaks indicated that ZnB 2 O 4 :Pr 3+ phosphor has four electron trap levels with energy values in the range of 0.5–1.5 eV These four traps have first order kinetic and are formed at high temperature region. Resulting values are utilized as a reference for the CGCD procedure and the trapping parameters from the TL glow curves are calculated. The figure of merit (FOM) of the TL glow curve during curve fitting procedures is found to be 2.019%. The intensities of the main dosimetric peaks appeared at 124 °C and 233 °C exhibits good linear dose response up to 20 Gy. These results provide valuable knowledge for use of the characteristics of Pr doped ZnB 2 O 4 in dosimetry research, just need to eliminate low temperature TL peak. © 2019 Elsevier LtdItem Comparative studies on thermoluminescence characteristics of non-doped Mg2SiO4 prepared via a solid-state reaction technique and wet-chemical method: An unusual heating rate dependence(Elsevier Ltd, 2019) Dogan T.; Akça S.; Yüksel M.; Kucuk N.; Ayvacikli M.; Karabulut Y.; Canimoglu A.; Topaksu M.; Can N.Magnesium orthosilicate (Mg2SiO4)was synthesized via a traditional solid-state reaction and a wet chemical route. This study primarily reported the thermoluminescence (TL)behavior of Mg2SiO4 host. X-ray diffraction pattern revealed that Mg2SiO4 exhibits orthorhombic structure matched with JCPDS card 900-6398. Dose response, reproducibility and trap parameters of TL glow curves were evaluated to clearly reveal TL features. Two TL glow peaks situated at 81 °C and 192 °C were monitored at a heating rate of 2 °Cs−1. We observed anomalous heating rate effect for the peak centered at 192 °C whilst TL intensity of the peak at 81 °C decreases with elevating heating rate. Trap depths of the electrons within the trap centers were found to be 1.04 ± 0.01eV and 1.37 ± 0.01eV for both methods using peak shape (PS)method. Distribution of trap centers was examined using the Tmax−Tstop method and this case indicated that the glow curves consist of single TL peaks. The intensity of TL glow curves exhibited a good linear dose response under total area up to 20 Gy. A comparison of the two preparation techniques revealed that TL characteristics of this phosphor are partly dependent and Mg2SiO4 could be a promising material for dosimetric application. © 2019 Elsevier B.V.Item Enhancing the blue luminescence behaviour of the Li co-doped novel phosphor ZnB2O4: Tm3+(Elsevier Ltd, 2020) Kucuk N.; Kaynar Ü.H.; Akca S.; Alajlani Y.; Yin L.; Wang Y.; Garcia Guinea J.; Bulcar K.; Dogan T.; Karabulut Y.; Ayvacikli M.; Canimoglu A.; Topaksu M.; Can N.Here we report a detailed structural analysis, and properties of the cathodoluminescence (CL), photoluminescence (PL) and 3D thermoluminescence spectra of the Tm3+ incorporated ZnB2O4 phosphor successfully synthesized through wet-chemical synthesis. The formation of a single-phase compound is verified through X-ray diffraction (XRD) studies. The phosphor shows an efficient blue emission located at 458 nm corresponding to 1D2→3F4 under both a low voltage electron beam and UV excitation. The optimal concentration of the doped Tm3+ is 0.5 mol% in CL and PL measurements. The corresponding concentration quenching mechanism is confirmed to be a multipole-multipole interaction, and the critical distance between Tm3+ ions is estimated to be 34 Å. Incorporating Li+ remarkably enhances the luminescence intensity probably because of the charge compensation effect. Li ions are speculated to fill the defects in the ZnB2O4 host and then the excitation energy transfers from the host to Tm3+. Surprisingly, the thermoluminescence spectra of ZnB2O4:Tm3+ and Li+ co-doped ZnB2O4:Tm3+ recorded in the temperature range 30–400 °C follow a different pattern compared with PL and CL data. The dominant signals come from Tm3+ sites. Above room temperature, the Tm3+ ions do not show the peak temperature movement, but do exhibit a different pattern with the addition of co-doped Li+ ions. These results indicate that these phosphors are promising candidates for luminescence-based optoelectronic devices. © 2020 Elsevier B.V.Item Urinary HSP70 improves diagnostic accuracy for urinary tract infection in children: UTILISE study(Springer Science and Business Media Deutschland GmbH, 2023) Yilmaz A.; Afonso A.C.; Akil I.; Aksu B.; Alpay H.; Atmis B.; Aydog O.; Bayazıt A.K.; Bayram M.T.; Bilge I.; Bulut I.K.; Buyukkaragoz B.; Comak E.; Demir B.K.; Dincel N.; Donmez O.; Durmus M.A.; Dursun H.; Dusunsel R.; Duzova A.; Ertan P.; Gedikbasi A.; Goknar N.; Guven S.; Hacihamdioglu D.; Jankauskiene A.; Kalyoncu M.; Kavukcu S.; Kenan B.U.; Kucuk N.; Kural B.; Litwin M.; Montini G.; Morello W.; Nayir A.; Obrycki L.; Omer B.; Ozdemir E.M.; Ozkayin N.; Paripovic D.; Pehlivanoglu C.; Saygili S.; Schaefer S.; Sonmez F.; Tabel Y.; Tas N.; Tasdemir M.; Teixeira A.; Tekcan D.; Tulpar S.; Turkkan O.N.; Uysal B.; Uysalol M.; Vaiciuniene D.; Yavuz S.; Yel S.; Yildirim T.; Yildirim Z.Y.; Yildiz N.; Yuksel S.; Yurtseven E.; Schaefer F.; Topaloglu R.Background: The accuracy of conventional urinalysis in diagnosing urinary tract infection (UTI) in children is limited, leading to unnecessary antibiotic exposure in a large fraction of patients. Urinary heat shock protein 70 (uHSP70) is a novel marker of acute urinary tract inflammation. We explored the added value of uHSP70 in discriminating UTI from other infections and conditions confused with UTI. Methods: A total of 802 children from 37 pediatric centers in seven countries participated in the study. Patients diagnosed with UTI (n = 191), non-UTI infections (n = 178), contaminated urine samples (n = 50), asymptomatic bacteriuria (n = 26), and healthy controls (n = 75) were enrolled. Urine and serum levels of HSP70 were measured at presentation in all patients and after resolution of the infection in patients with confirmed UTI. Results: Urinary (u)HSP70 was selectively elevated in children with UTI as compared to all other conditions (p < 0.0001). uHSP70 predicted UTI with 89% sensitivity and 82% specificity (AUC = 0.934). Among the 265 patients with suspected UTI, the uHSP70 > 48 ng/mL criterion identified the 172 children with subsequently confirmed UTI with 90% sensitivity and 82% specificity (AUC = 0.862), exceeding the individual diagnostic accuracy of leukocyturia, nitrite, and leukocyte esterase positivity. uHSP70 had completely normalized by the end of antibiotic therapy in the UTI patients. Serum HSP70 was not predictive. Conclusions: Urine HSP70 is a novel non-invasive marker of UTI that improves the diagnostic accuracy of conventional urinalysis. We estimate that rapid urine HSP70 screening could spare empiric antibiotic administration in up to 80% of children with suspected UTI. Graphical abstract: A higher resolution version of the Graphical abstract is available as Supplementary information [Figure not available: see fulltext.] © 2022, The Author(s), under exclusive licence to International Pediatric Nephrology Association.Item The relationship between urine heat shock protein 70 and congenital anomalies of the kidney and urinary tract: UTILISE study(Frontiers Media SA, 2023) Aksu B.; Afonso A.C.; Akil I.; Alpay H.; Atmis B.; Aydog O.; Bakkaloglu S.; Bayazıt A.K.; Bayram M.T.; Bilge I.; Bulut I.K.; Cetinkaya A.P.G.; Comak E.; Demir B.K.; Dincel N.; Donmez O.; Durmus M.A.; Dursun H.; Dusunsel R.; Duzova A.; Ertan P.; Gedikbasi A.; Goknar N.; Guven S.; Hacihamdioglu D.; Jankauskiene A.; Kalyoncu M.; Kavukcu S.; Kenan B.U.; Kucuk N.; Kural B.; Litwin M.; Montini G.; Morello W.; Obrycki L.; Omer B.; Misirli Ozdemir E.; Ozkayin N.; Paripovic D.; Pehlivanoglu C.; Saygili S.; Schaefer F.; Schaefer S.; Sonmez F.; Tabel Y.; Tas N.; Tasdemir M.; Teixeira A.; Tekcan D.; Topaloglu R.; Tulpar S.; Turkkan O.N.; Uysal B.; Uysalol M.; Vitkevic R.; Yavuz S.; Yel S.; Yildirim T.; Yildirim Z.Y.; Yildiz N.; Yuksel S.; Yurtseven E.; Yilmaz A.Background: Congenital anomalies of the kidney and urinary tract (CAKUT) are defined as structural malformations of the kidney and/or urinary tract. Heat shock proteins (HSPs) are expressed in the kidney in response to cellular changes, such as thermal, hemodynamic, osmotic, inflammatory, and mechanical stresses. This study aimed to assess uHSP70 levels during acute urinary tract infections (UTI) and non-infection periods in patients with CAKUT, and to evaluate whether uHSP70 is elevated in CAKUT subtypes. Methods: Among patients with CAKUT, 89 patients with UTI (CAKUT-A), 111 without UTI (CAKUT-B), and 74 healthy children were included in the study. uHSP70 levels were measured using enzyme-linked immunosorbent assay (ELISA). Results: uHSP70 level was significantly higher in the CAKUT-A group than in the CAKUT-B and healthy control groups (p < 0.0001). Moreover, the level of uHSP70 was significantly higher in the CAKUT-B group than in the control group (p < 0.0001), but was not different between the CAKUT subtypes (p > 0.05). Conclusion: Urine HSP70 can also be used to predict UTI in patients with CAKUT. Moreover, uHSP70 levels were higher in children with CAKUT during the non-infectious period than in healthy controls. This suggests that children with CAKUT are at risk of chronic non-infectious damage. Copyright © 2024 Aksu, Afonso, Akil, Alpay, Atmis, Aydog, Bakkaloglu, Bayazıt, Bayram, Bilge, Bulut, Cetinkaya, Comak, Demir, Dincel, Donmez, Durmus, Dursun, Dusunsel, Duzova, Ertan, Gedikbasi, Goknar, Guven, Hacihamdioglu, Jankauskiene, Kalyoncu, Kavukcu, Kenan, Kucuk, Kural, Litwin, Montini, Morello, Obrycki, Omer, Misirli Ozdemir, Ozkayin, Paripovic, Pehlivanoglu, Saygili, Schaefer, Schaefer, Sonmez, Tabel, Tas, Tasdemir, Teixeira, Tekcan, Topaloglu, Tulpar, Turkkan, Uysal, Uysalol, Vitkevic, Yavuz, Yel, Yildirim, Yildirim, Yildiz, Yuksel, Yurtseven and Yilmaz.Item Urine soluble TLR4 levels may contribute to predict urinary tract infection in children: the UTILISE Study(Springer Science and Business Media Deutschland GmbH, 2024) Aksu B.; Afonso A.C.; Akil I.; Alpay H.; Atmis B.; Aydog O.; Bayazıt A.K.; Bayram M.T.; Bilge I.; Bulut I.K.; Buyukkaragoz B.; Comak E.; Demir B.K.; Dincel N.; Donmez O.; Durmus M.A.; Dursun H.; Dusunsel R.; Duzova A.; Ertan P.; Gedikbasi A.; Goknar N.; Guven S.; Hacihamdioglu D.; Jankauskiene A.; Kalyoncu M.; Kavukcu S.; Kenan B.U.; Kucuk N.; Kural B.; Litwin M.; Montini G.; Morello W.; Obrycki L.; Omer B.; Oner H.A.; Ozdemir E.M.; Ozkayin N.; Paripovic D.; Pehlivanoglu C.; Saygili S.; Schaefer F.; Schaefer S.; Sonmez F.; Tabel Y.; Tas N.; Tasdemir M.; Teixeira A.; Tekcan D.; Topaloglu R.; Tulpar S.; Turkkan O.N.; Uysal B.; Uysalol M.; Vitkevic R.; Yavuz S.; Yel S.; Yildirim T.; Yildirim Z.Y.; Yildiz N.; Yuksel S.; Yurtseven E.; Yilmaz A.Background: One of the most common bacterial infections in childhood is urinary tract infection (UTI). Toll-like receptors (TLRs) contribute to immune response against UTI recognizing specific pathogenic agents. Our aim was to determine whether soluble TLR4 (sTLR4), soluble TLR5 (sTLR5) and interleukin 8 (IL-8) can be used as biomarkers to diagnose UTI. We also aimed to reveal the relationship between urine Heat Shock Protein 70 (uHSP70) and those biomarkers investigated in this study. Methods: A total of 802 children from 37 centers participated in the study. The participants (n = 282) who did not meet the inclusion criteria were excluded from the study. The remaining 520 children, including 191 patients with UTI, 178 patients with non-UTI infections, 50 children with contaminated urine samples, 26 participants with asymptomatic bacteriuria and 75 healthy controls were included in the study. Urine and serum levels of sTLR4, sTLR5 and IL-8 were measured at presentation in all patients and after antibiotic treatment in patients with UTI. Results: Urine sTLR4 was higher in the UTI group than in the other groups. UTI may be predicted using 1.28 ng/mL as cut-off for urine sTLR4 with 68% sensitivity and 65% specificity (AUC = 0.682). In the UTI group, urine sTLR4 levels were significantly higher in pyelonephritis than in cystitis (p < 0.0001). Post-treatment urine sTLR4 levels in the UTI group were significantly lower than pre-treatment values (p < 0.0001). Conclusions: Urine sTLR4 may be used as a useful biomarker in predicting UTI and subsequent pyelonephritis in children with UTI. Graphical abstract: [Figure not available: see fulltext.]. © 2023, The Author(s), under exclusive licence to International Pediatric Nephrology Association.