41. Tribological evaluation of vegetable ▫$oil/MoS_2$▫ nanotube-based lubrication of laser-textured stainless steelMarjetka Conradi, Bojan Podgornik, Maja Remškar, Damjan Klobčar, Aleksandra Kocijan, 2023, original scientific article Abstract: In the present work, the functionalisation of austenitic stainless steel, AISI 316L surfaces via nanosecond Nd:YAG laser texturing in order to modify the surface morphology with crosshatch and dimple patterns is presented. A tribological analysis under lubrication with sunflower and jojoba oil with and without the addition of a solid lubricant, MoS2 nanotubes, was performed. In conjunction with friction/wear response laser-textured surface wettability, oil spreadability and oil retention capacity were also analysed. It was shown that the crosshatch pattern generally exhibited lower friction than the dimple pattern, with the addition of MoS2 nanotubes not having any significant effect on the coefficient of friction under the investigated contact conditions. This was found in addition to the better oil spreadability and oil retention capacity results of the crosshatch-textured surface. Furthermore, texturing reduced the wear of the stainless-steel surfaces but led to an approximately one order of magnitude larger wear rate of the steel counter-body, primarily due to the presence of hard bulges around the textured patterns. Overall, the crosshatch pattern showed better oil retention capacity and lower friction in combination with different vegetable oils, thus making it a promising choice for improving tribological performance in various environmentally friendly applications.
Keywords: tribology, stainless steel, vegetable oil lubrication, MoS2 nanotubes
Published in DiRROS: 02.02.2024; Views: 126; Downloads: 72
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42. Predicting the quality of grain refiners from electrical resistance measurements of aluminumMaja Vončina, Irena Paulin, Jože Medved, Mitja Petrič, 2023, original scientific article Keywords: Al-Ti-B grain-refiners, quality, TiB2 particles, Al3Ti particles, electrical resistance measurements
Published in DiRROS: 01.02.2024; Views: 169; Downloads: 72
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44. Vehicle–bridge interaction modelling using precise 3D road surface analysisMaja Kreslin, Peter Češarek, Aleš Žnidarič, Darko Kokot, Jan Kalin, Rok Vezočnik, 2024, original scientific article Abstract: Uneven road surfaces are the primary source of excitation in the dynamic interaction between a bridge and a vehicle and can lead to errors in bridge weigh-in-motion (B-WIM) systems. In order to correctly reproduce this interaction in a numerical model of a bridge, it is essential to know the magnitude and location of the various roadway irregularities. This paper presents a methodology for measuring the 3D road surface using static terrestrial laser scanning and a numerical model for simulating vehicle passage over a bridge with a measured road surface. This model allows the evaluation of strain responses in the time domain at any bridge location considering different parameters such as vehicle type, lateral position and speed, road surface unevenness, bridge type, etc. Since the time domain strains are crucial for B-WIM algorithms, the proposed approach facilitates the analysis of the different factors affecting the B-WIM results. The first validation of the proposed methodology was carried out on a real bridge, where extensive measurements were performed using different sensors, including measurements of the road surface, the response of the bridge when crossed by a test vehicle and the dynamic properties of the bridge and vehicle. The comparison between the simulated and measured bridge response marks a promising step towards investigating the influence of unevenness on the results of B-WIM.
Keywords: interakcija vozilo in most, terestično lasersko skeniranje, neravnost vozišča, numerično modeliranje
Published in DiRROS: 26.01.2024; Views: 214; Downloads: 87
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45. Can we rely on cancer mortality data? Checking the validity of cervical cancer mortality data for SloveniaMaja Primic-Žakelj, Vera Pompe-Kirn, Fani Škrlec, Jožica Šelb-Šemerl, 2001, original scientific article Abstract: Background. Valid inference on cervical cancer mortality is very difficult since - on the basis of death certificates - it is not always possible to distinguish between cervix, corpus and unspecified uterine cancer deaths. Our aim was to estimate the extent to which cervical cancer as the official cause of death reflects the true mortality from cervical cancer in Slovenia. Material and methods. The data on 2245 deaths from cervix, corpus uteri, and uterus-unspecified cancers for the period 1985-1999 were linked to the Cancer Registry of Slovenia database from the mortality database of Slovenia. Results. Officially, in the period 1985-1999, there were 878 cervical cancer deaths. The comparison of these causes of death with the cancer sites registered in the Cancer Registry revealed that they include only 87.7 % patients with a previous diagnosis of cervical cancer. Of 650 corpus uteri cancer deaths, 17.1% of patients were registered to have cervical cancer, and of 717 unspecified uterine cancer deaths, 31.4% were registered. Taking into account the correctly identified cervical cancer cases among cervical cancer deaths and misclassified cervical cancer deaths as corpus uteri and unspecified uterine, the corrected number of deaths would be 1106. Conclusions. When evaluating the impact of cervical cancer mortality from national mortality rates, the stated underestimation should be taken into account. However, this does not hold for some other cancers.
Published in DiRROS: 26.01.2024; Views: 126; Downloads: 36
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46. MRI macromolecular contrast agents as indicators of changed tumor blood flowTeodora Ivanuša, Katarina Beravs, Maja Čemažar, Vladimir Jevtič, Franci Demšar, Gregor Serša, 2001, original scientific article Abstract: Background. A rapid mapping technique derived from dynamic contrast enhanced MRI data was used to identify and characterize reduction of blood flow in fibrosarcoma SA-1 tumors treated either by application of electric pulses or vinblastine. Materials and methods. Tissue permeability surface area product (PS) and fractional blood volume (BV) were calculated on a pixel-by-pixel basis using dynamic MRI intensity data after administration of gadomer - 17 orpolylysine-Gd-DTPA; prototypic macromolecular contrast agents designed for blood pool enhancement. PS and BV values of untreated tumors were compared to those of tumors treated by local application of 8 electric pulses (amplitude/distance ratio, 1300 V/cm; duration, 100 us, frequency, 1 Hz) percutaneously to the tumor or by systemic administration of vinblastine (2.5 mg/kg). Results. Both treatments transiently, but significantly reduced tumor blood flow, application of electric pulses to the tumors being by 40% more effective in reducing tumor blood flow than systemic administration of vinblastine. PS and BV values derived with polylysine-Gd-DTPA-enhanced MRI were lower compared to those with gadomer-17, due to larger molecular size. Interestingly, Gd-DTPA-enhanced MRI did not show any significant changes of PSand BV between untreated and treated tumors. Conclusion. This study demonstrates that dynamic contrast enhanced MRI can be effectively used to qualitatively monitor tumor blood flow, and quantitatively by means of BV and PS.
Published in DiRROS: 25.01.2024; Views: 160; Downloads: 35
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47. Computer systems for determination od pressure distribution in the hip joint articular surface : validation and resultsVlado Stankovski, Dragica Smrke, 2001, original scientific article Abstract: Background. In this work, we describe the computer systems Viprecox and ActiveContours that are used in the process of realistic estimation of some biomechanical parameters of the hip joint, including the maximal value of the stress in the hip joint p max. The computer system Active Contours uses standard anteroposterior radiographs of the whole pelvis and both hips for itscalculations and Viprecox in its kernel uses a relatively simple three-dimensional mathematical model of stress distribution in the hip-joint articular surface which has been extensively elsewhere (e.g. Iglič 1996). Material and methods. Both state-of-the-art computer systems were tested by analysing the calculated values of p max for 81 patients (37 males and 44 females). Conclusions. In this way we prove that the described computer systems can be used for the determination of the contact stress distribution from standard AP radiographs.
Published in DiRROS: 25.01.2024; Views: 154; Downloads: 29
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48. Antitumor effectiveness of bleomycin on SA-1 tumor after pretreatment with vinblastineMaja Čemažar, Marija Auersperg, Gregor Serša, 2000, original scientific article Abstract: In our previous study, vinblastine (VLB) was shown to increase the plasma membrane fluidity. This effect of VLB might be exploited for better transport of drugs through the plasma membrane. The aim of the present study was to determine whether pretreatment with VLB can increase the cytotoxic effect of BLM on intraperitoneal SA-1 tumors in mice. Materials and methods. BLM and VLBwere used as single agents or in various combinations, i.e. BLM injected 24h before VLB or vice-versa, VLB injected 24 h before BLM. Cell and animal survival together with DNA histograms were the end-points used to determine the effect of these combined treatments. Results. Both drugs, either as singletreatment or in different combined therapy schedules reduced significantly the number of cells in peritoneal lavage, compared to control, saline treated animals. The combination of VLB, followed by BLM after 24 h reduced significantly the number of cells in peritoneal lavage, compared to the treatment in which BLM was followed by VLB or to the treatment with singledrugs alone. Median survival time of mice treated with VLB alone, BLM alone and combination of both drugs was significantly prolonged compared to the control untreated mice. When VLB and BLM were combined, both treatment combinations were more effective than monochemotherapies with VLB or BLM. The best results were obtained when VLB was followed by BLM after 24 h. The DNA histogram of cells treated with VLB showed a decreased number of cells in S phase and an increased number of cells with DNA values greater than in G2M compartment compared to the control untreated cells. BLM in the dosage used inthese experiments did not affect the progression of cells through cell cycle. Both combinations of VLB and BLM produced similar cell kinetic effect as VLB alone. Conclusion. (Abstract truncated at 2000 characters.)
Published in DiRROS: 23.01.2024; Views: 149; Downloads: 30
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49. Cathepsin D and plasminogen activator inhibitor type 1 in normal, benign and alignant ovarian tissues : a preliminary reportMarina Šprem, Damir Babić, Marija Abramić, Duško Miličić, Ivan Vrhovec, Janez Škrk, Maja Osmak, 2000, original scientific article Abstract: Background. The aim of the present study was to determine the concentration ofcathepsin D (Cath D) and plasminogen activator inhibitor type 1 (PAI-1) in normal ovarian tissues, benign and malignant ovarian tumor tissues, and to asses relationship between Cath D and PAI-1 content, and some clinical and pathohistological parameters. Materials and methods. Cath D contents and PAI-1concentrations were determined (using immunoradiometric ELSA-Cath D assayand commercial IMUDIND R ELISA immunoassay, respectively) in 35 samples: 10 normal ovarii, 10 benign, 10 primary malignant and 5 metastatic ovarian tumors. Results. The concentrations of Cath D were significantly higher in malignant (32.89+-14.26 pmol/mg protein ) and metastatic (31.42+-10.24 pmol/mgprotein), than in normal (13.68+-4.03 pmol/mg protein) and benign (17.89+-13.13 pmol/mg protein) ovarian tissues. There was no statistical differences in the concentrations of PAI-1 between normal, benign, malignant and metastatic tumor specimens. The concentrations of Cath D as well as PAI-1 did not correlate to the age of patients, menopausal status, parity, GOG risk group, clinical stage or pathohistological grading. Conclusion. Concentrationsof Cath D (but not PAI-1) were significantly increased in malignant and metastatic ovarian tumor tissues when compared to normal and benign ovarian tumor samples; they were independent from pathohistological andclinical parameters.
Published in DiRROS: 23.01.2024; Views: 156; Downloads: 52
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50. Comprehensive permanent remote monitoring system of a multi-span highway bridgeAndrej Anžlin, Uroš Bohinc, Doron Hekič, Maja Kreslin, Jan Kalin, Aleš Žnidarič, 2021, published scientific conference contribution Abstract: As part of the reconstruction of a multi-span viaduct on a Slovenian highway, a permanent remote monitoring system with over 200 sensors was established. Several parameters are monitored on different parts of the viaduct by means of temperature sensors, accelerometers, strain gauges, long-gauge deformation and Fibre Bragg Grating (FBG) sensors. In this way strains, frequencies and temperatures on external prestressed beam cables, carbon fibre rebarsused for the flexural strengthening of a deck overhang, pier caps and prestressed beams are measured and stored into the on-site central data acquisition system. This paper presents architecture of the permanent bridge monitoring system and preliminary results of the measurements.
Keywords: permanent monitoring, structural health monitoring, bridge WIM, sensors, viaduct
Published in DiRROS: 22.01.2024; Views: 231; Downloads: 105
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