41. |
42. |
43. Influence of magnesium sulphate infusion before total thyroidectomy on transient hypocalcemia - a randomised studyNikola Bešić, Špela Žagar, Gašper Pilko, Barbara Perić, Marko Hočevar, 2008, original scientific article Abstract: Background. Transient hypocalcemia is the most common complication after thyroidectomy. Normomagnesemia is needed for normal secretion of PTH and end-organ responsiveness. Our aim was to determine the influence of infusion of magnesium sulphate before thyroidectomy on the incidence of laboratory and clinical transient hypocalcemia. Methods. In our prospective study, 48 patients (5 men, 43 women; age 22-73 years, median 45 years), who underwent total or near-total thyroidectomy, were randomised preoperatively. Half of them received intravenously 4 ml of 1M magnesium sulphate at the beginning of the surgical procedure, the other half were the control group. Serum concentrations of calcium, ionised calcium, magnesium, phosphate, albumin and PTH were measured prior to surgery and on the first day after surgery. Results. Laboratory postoperative hypocalcemia was present in 27% of patients and 23% of patients had clinical signs and/or symptoms of postoperative hypocalcemia. The concentration of total calcium (p=0.024) and of albumin (p=0.01) was lower in the group that received magnesium sulphate. Conclusions.The patients who received infusion of magnesium sulphate before total thyroidectomy had lower concentration of total serum calcium and albuminin comparison to the control group. There was no statistical differencein the incidence of clinical transient hypocalcemia.
Published in DiRROS: 08.03.2024; Views: 89; Downloads: 25
 Full text (72,12 KB) |
44. The use of paper industry side product in constructionBarbara Likar, Laura Vovčko, 2020, published scientific conference contribution Abstract: The amount of waste material and side products of various industrial plants is increasing, which leads into waste accumulation and lack of space in disposal landfills. Paper industry, with its side products paper sludge and ash, faces these same issues. To reduce the accumulation of these materials, we explored the possibility of their use in construction. At first a series of geomechanical tests was conducted on a product consisting of fly ash and bottom ash. Based on the laboratory results test fields were constructed, where the preparation and installation technologies were tested. The fields were exposed to the atmospheric conditions, so durability of the product in the natural environment was proven. Since the composition of both fly ash and bottom ash depends on the paper industry process, a continuous monitoring of their characteristics was established.
Keywords: paper industry, fly ash, bottom ash, construction material, geomechanical properties
Published in DiRROS: 05.03.2024; Views: 134; Downloads: 48
Full text (521,45 KB)
This document has many files! More... |
45. Thermal insulation and flammability of composite waste polyurethane foam encapsulated in geopolymer for sustainable building envelopeBarbara Horvat, Nataša Knez, Uroš Hribar, Jakob Koenig, Branka Mušič, 2024, original scientific article Abstract: Polyurethane foam (PUR) is a lightweight, thermally insulating, widely used, and highly flammable material that has after its use an adverse effect on the environment, i.e., PUR disposal is considered hazardous. Its flammability can be mitigated using various fire retardants, but they do not change the hazardous nature of waste PUR. Therefore, in the current study, waste PUR with and without flame retardants based on N and P was incorporated into a geopolymer, the alkali-activated material (AAM) based solely on metakaolin, to evaluate the potential recycling route of waste PUR while taking into account its flammability, so it can enter safely into the circular economy through the building industry. To enhance the mechanical properties of the composite, a fresh mixture was irradiated with microwaves. However, the irradiation of geopolymer containing PUR negatively influenced mechanical performance, which led to the evaluation of the behaviour of the complex dielectric constant of PUR and fire retardants. Materials and composites were evaluated regarding their chemistry, mineralogy, microstructure, and porosity to connect the structure with extrinsic properties like geometrical density, thermal conductivity, and fire properties. Nonetheless, positive influences of PUR being encapsulated in the geopolymer were lowered density (from 1.8 to 1.6 kg/l) and improved thermal insulation ability (from 940 to 860 mW/(m·K)) of the composites: with the inclusion of <5 % of PUR, thermal insulation improved by nearly 10 %. However, the contribution of PUR to the composite originated from its skeleton, which has more than 15 times bigger geometrical density (0.81 kg/l) compared to the density of the skeleton (0.047 kg/l). This offers an open field for further advancements of thermal properties, but would also lead to a decrease of the compressive strength, which was already lowered from 90 MPa for 30 % with <5 % of added grated PUR. Furthermore, the flammable nature of PUR and its other drawbacks can be controlled by permanent embedding in the noncombustible structure of geopolymer, making the envelope of sustainable buildings green and safer. Overall, including grated waste PUR in geopolymer represents a promising, easy, cost-effective recycling path with low energy consumption, where the composite cannot develop fire on a scale of pure PUR, even in the worst-case scenario, but only if the composite is designed in a way, that flammable materials cannot join flames during their combustion. This paper gives prospects to other flammable waste materials to be safely used in the circular economy, and to porous materials to shape properties of the composite by their intrinsic and/or extrinsic properties.
Keywords: waste polyurethane foam, polymeric flame retardants, alkali activated material, metakaolin, microwave irradiation, thermal-fire behaviour, mechanical strength
Published in DiRROS: 01.03.2024; Views: 178; Downloads: 162
Full text (29,74 MB)
This document has many files! More... |
46. Foundry wastes as a potential precursor in alkali activation technologyBarbara Horvat, Alenka Sešek Pavlin, Vilma Ducman, 2020, published scientific conference contribution Abstract: In this study the amount of amorphous phase of elements useful in alkali activation of waste materials produced by the foundry industry was determined. Waste foundry sands, foundry flue gas and waste casting cores were alkali activated, and waste green ceramics and bottom ash were added to one of the foundry sand samples to shorten the time for producing measurable compressive strength from 1.5 years to 1 week.
Keywords: alkali activated materials, foundry wastes, compressive strength, upcycling, circular ecnomy
Published in DiRROS: 01.03.2024; Views: 117; Downloads: 49
 Link to file
This document has many files! More... |
47. Enhancing ductility of hot-work tool steel through isothermal bainitic transformationAnže Bajželj, Aleš Nagode, Tilen Balaško, Barbara Šetina, Jaka Burja, 2024, published scientific conference contribution Abstract: Hot-work tool steels are extensively used in industrial applications that require high resistance to mechanical and chemical degradation at elevated temperatures. To meet these requirements, hot-work tool steels must exhibit good mechanical properties, including high tensile strength, hardness, wear resistance, and tempering resistance, as well as high thermal conductivity and ductility. This study investigates the ductility of the hot-work tool steel HTCS-130, which suffers from low ductility due to the presence of stable molybdenum-tungsten carbides (M6C) on the prior austenite crystal grain boundaries. Increasing austenitisation temperatures or prolonging the dwelling time at temperature can promote intensive migration of grain boundaries, leading to negative effects on the mechanical properties of the steel. To address this issue, isothermal transformation in the bainitic area between 350 and 500 °C was performed. Isothermal transformation at around 350 °C leads to the formation of lower bainite, which has similar hardness to tempered martensite. As the temperature of isothermal transformation increases, the hardness of the material decreases, due to the formation of upper bainite. The hardness analysis was measured using the Vickers method, the impact toughness of the steel samples was measured using a Charpy test with V-notched samples. The microstructure characterization was performed using optical and scanning electron microscopy. The improvement of ductility can be achieved by controlling the isothermal transformation of bainite and adjusting the heat treatment conHot-work tool steels are extensively used in industrial applications that require high resistance to mechanical and chemical degradation at elevated temperatures. To meet these requirements, hot-work tool steels must exhibit good mechanical properties, including high tensile strength, hardness, wear resistance, and tempering resistance, as well as high thermal conductivity and ductility. This study investigates the ductility of the hot-work tool steel HTCS-130, which suffers from low ductility due to the presence of stable molybdenum-tungsten carbides (M6C) on the prior austenite crystal grain boundaries. Increasing austenitisation temperatures or prolonging the dwelling time at temperature can promote intensive migration of grain boundaries, leading to negative effects on the mechanical properties of the steel. To address this issue, isothermal transformation in the bainitic area between 350 and 500 °C was performed. Isothermal transformation at around 350 °C leads to the formation of lower bainite, which has similar hardness to tempered martensite. As the temperature of isothermal transformation increases, the hardness of the material decreases, due to the formation of upper bainite. The hardness analysis was measured using the Vickers method, the impact toughness of the steel samples was measured using a Charpy test with V-notched samples. The microstructure characterization was performed using optical and scanning electron microscopy. The improvement of ductility can be achieved by controlling the isothermal transformation of bainite and adjusting the heat treatment conditions. These findings provide useful insights into the design and optimization of heat treatment processes for hot-work tool steels.ditions. These findings provide useful insights into the design and optimization of heat treatment processes for hot-work tool steels.
Keywords: hot-work tool steel, austempering, bainitic transformation, ductility, dilatometry
Published in DiRROS: 28.02.2024; Views: 131; Downloads: 60
Full text (1,02 MB)
This document has many files! More... |
48. Testing of mechanisms of action of rituximab and clinical results in high-risk patients with aggressive CD20+ lymphomaBarbara Jezeršek Novaković, Vladimir Kotnik, Tanja Južnič Šetina, Marjeta Vovk, Srdjan Novaković, 2007, original scientific article Abstract: Background. Rituximab has been applied successfully in the treatment of indolent and aggressive CD20 positive B cell lymphomas, yet the exact in vivo mechanisms of its action have not been unambiguously explained. This study wastherefore aimed to confirm the presumed major mechanisms of action of rituximab and concomitantly to assess the effectiveness of first-line chemoimmunotherapy in high-risk patients with aggressive CD20 lymphomas. Patients, materials and methods. The activity of rituximab was tested in vitroon Raji and SU-DHL-4 cells using the cell proliferation assay and flow cytometry. In the clinical part of the study, 20 high-risk patients with aggressive CD 20 lymphomas were treated with R-CHOP. Results. Only complement-mediated cytotoxicity was observed under the in vitro applied experimental conditions. Neither the direct apoptotic effect nor the antibody-dependent cell-mediated cytotoxicity was detected probably due to a too low concentration of rituximab and a too low ratio of cytotoxic lymphocytes to tumor cells. The treatment outcome in patients was excellent since complete remissions were achieved in 90% of poor-risk patients at the end of primary treatment and 80% of patients were disease free at 18.5 months median observation period. Conclusions. According to our results, the complement-dependent cytotoxicity is an important mechanism of rituximab action in vitro. To achieve direct apoptosis, higher concentrations than 20 micro g/ml of rituximab should be used, while for an effective antibody-dependent cell-mediated cytotoxicity, the ratio of cytotoxic lymphocytes to tumor cells should be higher than 1:1. In the high- risk patients with aggressive CD20 lymphomas, the addition of rituximab to CHOP substantially improves the therapeutic results.
Published in DiRROS: 22.02.2024; Views: 136; Downloads: 36
Full text (232,23 KB) |
49. PUR in geopolymerBarbara Horvat, Nataša Knez, Uroš Hribar, Jakob Koenig, Branka Mušič, 2024, complete scientific database of research data Abstract: The dataset supports the results shown in the tables and figures in the article entitled “Thermal insulation and flammability of composite waste polyurethane foam encapsulated in geopolymer for sustainable building envelope” (doi: 10.1016/j.jclepro.2024.141387). It contains measurements of fire-behaviour characteristics, thermal conductivity, the behaviour of the material in the electromagnetic field in relation to the frequency, mechanical and structural evaluation, as well as chemical and mineralogical analysis.
Keywords: measurements, waste polyurethane foam, polymeric flame retardants, alkali activated material, metakaolin, microwave irradiation, thermal-fire behaviour, mechanical strength
Published in DiRROS: 20.02.2024; Views: 251; Downloads: 167
 Research data (2,51 MB)
This document is also a collection of 1 document! |
50. Rituximab affects the prognosis of patients with nonHodgkin's lymphomasBarbara Jezeršek Novaković, Marjeta Vovk, Simona Borštnar, Radka Tomšič, 2004, original scientific article Abstract: Backround. Rituximab - the most widely used monoclonal antibody in the B cell lymphoid malignancies has been applied successfully in the treatment of relapsed and refractory indolent CD20 positive B cell lymphomas and more recently, also in the treatment of aggressive lymphomas in combination with standard chemotherapy. Albeit the chemo-immunotherapy has a wide range of potential applications, there are still several issues that have to be resolved: (1) the optimal scheduling of antibody-chemotherapy combinations, (2) the most active of these combinations, as well as (3) the predictors of response to rituximab. Patients and methods. To facilitate addressing the first two questions, we performed an analysis in 25 patients with different histological types of CD20 positive nonHodgkin's lymphomas (10 aggressive and 15 indolent). Seventeen patients were treated with chemo-immunotherapy for a relapse, and just in 8 patients rituximab was added to first line chemotherapy. Most of the responders received the CHOP regimen, but also otherregimens (FC, BVCPP) were effective in combination with rituximab. Results. The overall response rate was 76%, with 68% complete remissions. The median response duration has not been reached yet. The response was markedly better in the group of previously untreated patients, where the overall response rate reached 100%, with 7 patients in complete and 1 patient in partial remission. Most of the treatment failures occurred in heavily pretreated patients with aggressive lymphomas. No serious adverse effects wereobserved. Conclusion The chemo-immunotherapy improves the treatment outcomes in patients with untreated and relapsed CD20 positive nonHodgkin's lymphomas in comparison to chemotherapy alone. The combined treatment is the most effective when used as soon as possible (preferably as the first line treatment). (Abstract truncated at 2000 characters).
Published in DiRROS: 07.02.2024; Views: 178; Downloads: 39
Full text (4,61 MB) |
