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High-temperature oxidation of boiler steels at 650 °C
Jaka Burja, Barbara Šetina, Borut Žužek, Tilen Balaško, 2023, original scientific article

Abstract: This study presents a comprehensive investigation of the formation, composition and behaviour of oxide layers during the high-temperature oxidation of four different steel alloys (16Mo3, 13Cr, T24 and P91) at a uniform temperature of 650 °C. The study is aimed at assessing the oxidation damage due to short-term overheating. The research combines CALPHAD (CALculation of PHAse Diagrams) calculations, thermogravimetric analysis (TGA) and advanced microscopy techniques, in- cluding scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD), to elucidate the complex mechanisms controlling oxidation kinetics and oxide layer development. CALPHAD calculations were used to determine the thermodynamically stable phases for each steel type at 650 ◦C and different oxygen activities. The results showed different phase compositions, highlighting the importance of the chromium content in steel for the formation of oxide layers. The different oxidation kinetics and oxide layer compositions are presented and associated with the increased risk of material degradation due to overheating. These results have significant implications for industrial applications, mainly the susceptibility to oxidation of low-alloyed steels like 16Mo3 and 13 Cr and contribute to a deeper understanding of oxidation processes in steels.
Keywords: high-temperature oxidation, thermogravimetric analysis, kinetics, CALPHAD, boiler steels, SEM, EBSD
Published in DiRROS: 26.01.2024; Views: 191; Downloads: 77
.pdf Full text (12,99 MB)
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13.
Radical irradiation of the prostate. Combination of percutaneous irradiation and irradiation with LDR Ir-192 implants
Borut Kragelj, Franc Guna, Janez Burger, 2001, original scientific article

Abstract: Background. The irradiation of the carcinomas of the prostate with the doses above the tolerable ones of standard radiotherapy improves the local control of the disease. The aim of this study is to determine the acute toxicity and tolerability of the high-dose prostate irradiation combining external beam radiotherapy (EBRT) and interstitial low dose rate (LDR) brachyradiotherapy (BRT) Ir-192 of the prostate. Material and methods. We examined medical records of 8 patients with localized carcinoma of the prostate (T2-T3 No-x Mo)treated from August 1999 until February 2000. The initial PSA was 2.7-37.5 ng/ml (median 13.7) and Gleason score 4-9 (median 7). Radiotherapy consisted of 48.6-50.4 Gy of EBRT to the prostate and seminal vesicles (4 patients) or the whole pelvis (4 patients) and 20.0-28.0 Gy of interstital LDR Ir-192 BRT given as a single fraction, fluoroscopic guided transperineal Implantation of the prostate. The cumulative doses of percutaneous and interstitial irraditations to the prostate were 68.6 - 79.1 Gy. Results. Acute toxic effects of irradiation though observed in all patients were of only mild intensity. According to the RTOG criteria, 20/30 toxicities were assessed as grade 1, 9/30 as grade 2, and 1/30 as grade 3. In none of the patients, toxic effects required any specific modification of the treatment regimen. Conclusions. The very first experiences indicate moderate toxicity and optimaltolerance of the treatment by patients. An improvement of implantation techniques may be expected with regular CT controls of the implants and extra attentive care of the implants in the urethra region.
Published in DiRROS: 25.01.2024; Views: 143; Downloads: 31
.pdf Full text (223,53 KB)

14.
Improving the quality of life of patients with TCC by sequential chemoradiothrapy
Borut Kragelj, Boris Sedmak, Jožica Červek, Tanja Čufer, 2000, published scientific conference contribution abstract

Published in DiRROS: 25.01.2024; Views: 142; Downloads: 33
.pdf Full text (94,20 KB)

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Assessment of renal function from creatinine clearance measurement and 131I-hippuran renography in cancer patients before chemotherapy
Borut Štabuc, Tine Hajdinjak, Tomaž Edvard Cizej, 1999, original scientific article

Abstract: Background. Serum creatinine and endogenous creatinine clearance (CrCl) are widely used measures of renal function before prescribing nephrotoxic chemotherapy. This study compares the precision and bias in glomerular filtration rate (GFR) estimation without the need to collect urine by using Cockcroft-Gault formula on a single serum creatinine concentration (CrCo) and 131I- hippuran clearance (HC) determined from the renographic curves. Patientsand methods. Fourty-seven patients aged between 27 and 73 years were studied. In all patients, we determined serum creatinine concentration, CrCl, CrCo and HC simultaneously before treatment by combined chemotherapy with cisplatin (CDDP) and in 31 patients, before the third cycle. Serum and urine creatinine concentrations were determined with a Hitachi 911, an automated biochemical analyser CrCl was calculated from the urine flow, from the ratio between the serum and urine creatinine concentrations and was standardized forthe body surface area. Serum creatinine was used to estimate CrCo using a Cockcroft and Gault formula. HC was determined from 131I-hippuran uptake by both kidneys, results were compared to our Nuclear Medicine Department normal values with regard to the age of each patient. For the evaluation of results, Pearson's correlation coefficient and t-test with 95 % confidence interval were used. Results. The sensitivity of serum creatinine, CrCo and HC to predict CrCl<78 mL/min/1.73m2 was 41 %, 68% and 46% and specificity was 95%, 71 % and 76% respectively. Value of CoCr for prediction of reduced CrCl (sensitivity) was statistically significantly better than the HC (p=0.03). Value of CoCr fnr prediction of normal CrCl (specificity) was as good as HC (p=0.3). Conclusions. CrCl for the GFR estimation in the patients treated withnephrotoxic chemotherapy cannot be changed by CrCo and/or HC.
Published in DiRROS: 22.01.2024; Views: 141; Downloads: 38
.pdf Full text (463,87 KB)

17.
Phase II study of fluorouracil, leucovorin and interferon alpha-2a in patients with advanced colon cancer
Borut Štabuc, Aleksandra Markovič, Erik Brecelj, Samir Bešlija, Tomaž-Edvard Cizej, 1998, original scientific article

Abstract: Based on in viro studies that have demonstrated synergy between fluorouracil (5-FU) and leucovorin (LV) as well as between 5-FU and recombinant alpha-2a interferon (IFN) against colon cancer cell lines a phase II study was carried out to evaluate the toxicity and clinical activity of 5-FU modulated with LV and IFN in patients with metastatic colon cancer. Twenty-two chemotherapy naive patients with measurable metastases of colon cancer have been treated with daily doses of 5-FU 600 mg/m2 in 6-hr intravenous infusion, and of LV 20 mg/m2 intravenously and IFN 6 MU subcutaneously, for 5 days every 4 weeks. Median age was 60 years, median PS (ECOG) was 1 (range 0-2). Liver, soft tissue and lung metastases were found in 12, 5 and 8 patients, respectively. Nineteen patients had a single metastatic site, two double, whereas one had more than two metastatic sites. Patients had 2-9 (mean 5) cycles of treatment.Objective response was observed in 7 patients (32%), and stable disease in 7 patients (32%). Overall median survival was 12.5 months, and for responders 14.4 months. Responses were generally short and median time for progression was 5.5 months. The most frequent adverse reactions were flu-like syndrome (50%), nausea/vomiting (36%), diarhoea (13Č), stomatitis (27%) and leucopenia (13%). This regimen of 5-FU with LV and IFN administration does notappear to be superior to previously published shedules of 5-FU with IFN or 5-FU with LV.
Published in DiRROS: 19.01.2024; Views: 135; Downloads: 40
.pdf Full text (430,62 KB)

18.
Acceptability of simultaneous irradiation and mono/polichemotherapy with cis/carboplatin
Borut Kragelj, 1998, original scientific article

Published in DiRROS: 19.01.2024; Views: 128; Downloads: 34
.pdf Full text (329,93 KB)

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