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453.
Effect of sucrose concentration on streptococcus mutans adhesion to dental material surfaces
Anamarija Zore, Franc Rojko, Nives Matijaković Mlinarić, Jona Veber, Aleksander Učakar, Roman Štukelj, Andreja Pondelak, Andrijana Sever Škapin, Klemen Bohinc, 2024, izvirni znanstveni članek

Povzetek: Enamel demineralization, known as dental caries, is instigated by the bacterium Streptococcus mutans, which generates acid during carbohydrate metabolism. Among carbohydrates, sucrose is the most cariogenic and capable of biofilm formation. This study aimed to explore and comprehend Streptococcus mutans’ adherence to two prevalent dental material surfaces, i.e., a cobalt–chromium(Co-Cr) alloy and a resin-based composite, under the influence of various sucrose concentrations. To understand bacterial adhesion, the surfaces were characterized using profilometry, tensiometry, and surface charge measurements. Bacterial adhesion was evaluated using scanning electron microscopy and crystal violet dye methods. Results revealed that the composite surface exhibited greater rough-ness compared with the Co-Cr alloy surface. Both surfaces displayed hydrophilic properties and a negative surface charge. Bacterial adhesion experiments indicated lower bacterial adherence to the Co-Cr alloy than to the composite surface before the addition of sucrose. However, the introduction of sucrose resulted in biofilm development on both surfaces, showcasing a similar increase in bacterial adhesion, with the highest levels being observed at a 5% sucrose concentration in the bacterial suspension. In conclusion, the findings suggest sucrose-rich foods could facilitate bacterial adaptation despite less favorable surface characteristics, thereby promoting biofilm formation.
Ključne besede: bacterial adhesion, streptococcus mutans, dental material surfaces, sucrose concentration
Objavljeno v DiRROS: 31.01.2024; Ogledov: 128; Prenosov: 52
.pdf Celotno besedilo (4,28 MB)
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454.
The influence of different fibres quantity on mechanical and microstructural properties of alkali-activated foams
Katja Traven, Mark Češnovar, Barbara Horvat, Vilma Ducman, 2022, objavljeni znanstveni prispevek na konferenci

Povzetek: Alkali activated foams (AAFs) were produced using electric arc furnace steel slag (EAF) and ladle furnace basic slag (LS), obtained from two metallurgical companies in Slovenia. They were activated with a mixture of sodium water glass (Na2SiO3) and solid NaOH and foamed with hydrogen peroxide (H2O2). Pores were stabilized with the addition of Triton as a surfactant. Four types of fibres were added to the studied mixture (polypropylene (PP), polyvinyl-alcohol (PVA), basalt (B), and glass wool (GW)) in five different quantities: 0.5, 1.0, 1.25, 1.5 and 2.0 vol % in order to additionally stabilize the structure and thus improve its mechanical properties. The results of mechanical properties showed, that compressive strength was increased in all 20 specimens, partially due to the increased density as well as to the fibre addition. Flexural strength on the other hand was the most improved in the samples where PP and PVA fibres were added. The samples with the addition of B and GW fibres on the other hand showed only small or no improvement in flexural strength in comparison to the referenced sample. Additionally, the microstructure of used fibres and selected foams was also investigated by the means of SEM analysis.
Ključne besede: fibers, alkali activated foams, properties
Objavljeno v DiRROS: 31.01.2024; Ogledov: 117; Prenosov: 48
.pdf Celotno besedilo (4,05 MB)
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455.
Bio-solution for global sand crisis and sustainable organic agriculture in desert states
Darina Štyriaková, Iveta Štyriakova, Jaroslav Šuba, Felix Föhre, 2022, objavljeni znanstveni prispevek na konferenci

Povzetek: Sand is an important component of many everyday items, and currently sand is the second most extracted resource on earth after water, but it is not sustainable: we are running out of sand! The black market is booming, and the sand mafia is mining sand at any price. Desert sand is unusable, even Dubai must import it. The smooth surface and iron impurities prevent its industrial use. In this study, bacteria in the bioleaching test attacked the surface of the mineral grains and dissolved impurities including iron through organic acids. Furthermore, the liquid residue containing dissolved iron, organic acids and bacteria stimulated the growth plant what can be a valuable biofertilizer and biostimulant for organic agriculture. Desert states have fertility problems. Despite this, Qatar, for example, is aiming for self-sufficiency in vegetables “in five years”. Results showed that bioleaching combined with magnetic separation resulted in iron removal of 73.23%. The sand after treatment can be suitable to produce clear flat glass, coloured container glass, insulating glass fibres or ceramics. The integrated technology based ecological study revealed overall as utilization potential of the desert sand and the liquid residue could support glass and food production in desert states.
Ključne besede: materials, sand, bioleaching, sustainable organic agriculture, desert states
Objavljeno v DiRROS: 31.01.2024; Ogledov: 155; Prenosov: 92
.pdf Celotno besedilo (443,33 KB)
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456.
Rejuvenator obtained by pyrolysis of waste tires for use in asphalt mixtures with added reclaimed asphalt
Lidija Ržek, Mojca Ravnikar Turk, Marjan Tušar, 2022, samostojni znanstveni sestavek ali poglavje v monografski publikaciji

Povzetek: Although in recent years, big progress has been made in the field of recovering waste tires, they still represent an unwanted waste and their production is constantly increasing. We can use waste tires as a raw material for a new product. In our study, multiple liquid products were produced by pyrolysis of waste tires. After extensive testing of their properties, we selected the most suitable pyrolytic product for the purpose of rejuvenation. Rejuvenators are designed to soften the old, brittle and stiff aged bitumen in reclaimed asphalt. Bitumen with its viscoelastic characteristics is the most important component of asphalt and dictates its behaviour. Commonly bitumen, after adding rejuvenator, becomes less viscous, more ductile and its coating properties are restored. By using a pyrolytic rejuvenator, the proportion of reclaimed asphalt added to the asphalt mixture was increased. The reuse of reclaimed asphalt and waste tires means a reduction in waste material and is therefore important for the preservation of the environment and sustainable development.
Ključne besede: pyrolyse, rejuvenator, bitumen, reclaimed asphalt, waste tires
Objavljeno v DiRROS: 31.01.2024; Ogledov: 119; Prenosov: 50
.pdf Celotno besedilo (840,71 KB)
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457.
Development of an advanced methodology for assessing the environmental impacts of refurbishments
Tajda Potrč Obrecht, Sabina Jordan, Andraž Legat, Marcella Ruschi Mendes Saade, Alexander Passer, 2022, objavljeni znanstveni prispevek na konferenci

Povzetek: The refurbishment of the building stock is one of the key tasks for reducing the future environmental emissions in building sector. The assessment of the environmental impacts (EI) of refurbishments with LCA methodology remains a challenge. In the current practice, the refurbishment is threated as the beginning of the new lifecycle and all the impacts associated with the previous life cycle are generally neglected. The exclusion of materials and components used prior to the refurbishment produces a data gap at the end-of-life since information about materials that remained in the building after the refurbishment are missing. Furthermore, no information about what impacts have already been considered in the past bears the risk that some of the impacts are double-counted. In order to overcome these problems, an advanced methodology for the assessment of the embodied impacts in the case of refurbishment was developed that combines two sub-methodologies that can also be used separately. The first submethodology is used for remodelling the input data in order to make them time corresponding. The second sub-methodology is used for the assessment of the EI in the residual value of building materials and components and is including the allocation of EI between the life cycle before and after the refurbishment. The combination of the two sub-methodologies enables a more realistic and accurate assessment of the environmental impacts. The methodology is illustrated on the case on the case of a façade refurbishment. Five different allocation approaches are investigated and the residual value is calculated after a selected time period before and after the refurbishment. For all the inputs time-corresponding data is modelled and used. The study showed that for the life cycle before the refurbishment the EI and the residual value are generally higher if time-corresponding data is used since the EI of the electricity mix are higher. It turned out that the use of different allocation approaches is favouring either the use of recycled or reused materials or the recycling of the materials at the end. The PEF and the cut-off approach with module D are both enhancing the circular economy. It can be assumed that they are likely to prevail in the future.
Ključne besede: LCA, refurbishment, allocation, module D, dynamic LCA
Objavljeno v DiRROS: 31.01.2024; Ogledov: 112; Prenosov: 53
.pdf Celotno besedilo (1,62 MB)
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458.
Cysteine proteinase inhibitors stefin A and stefin B in operable carcinoma of the head and neck : Inhibitorji cisteinskih proteinaz stefin A in stefin B pri operabilnem karcinomu glave in vratu
Primož Strojan, Marjan Budihna, Alojz Šmid, Branka Svetic, Ivan Vrhovec, Janko Kos, Janez Škrk, 2002, izvirni znanstveni članek

Povzetek: Purpose. To evaluate the significance of cysteine proteinase inhibitors stefins (Stefs) A and B for a treatment decision and prognosis in operable squamous cell carcinoma of the head and neck (SCCHN). Patients and methods. Stefs A and B concentrations were determined immunobiochemically using ELISAs in cytosols prepared from the tumor and adjacent normal mucosa from 91 patients with operable SCCHN. The median follow-up period of patients alive atthe close-out date was 5.8 years (range, 5-9.3 years). Results. Stef A concentrations were significantly higher in tumor compared to normal mucosa (FM.05). When a subgroup with clinically palpable nodes) at presentation was taken into consideration (n=57), a significant difference in Stef A (P=0.03) and Stef B (P=0.02) concentrations between those with negative and positive necks, as determined on histopathological examination, was observed. On the univariate survival analysis, higher Stefsć concentrations turned to be prognostically advantageous. Stef A proved its independent prognostic significance also on multivariate setting. Conclusions. With the capability todifferentiate between the pN0- and pN+-stages of the disease in the patientsoriginally presented as node-positive, Stefs A and B could be useful markers when deciding on the extent of neck surgery. In addition, both Stefs proved to be reliable prognosticators for survival in patients with operable SCCHN.
Objavljeno v DiRROS: 31.01.2024; Ogledov: 120; Prenosov: 30
.pdf Celotno besedilo (114,91 KB)

459.
460.
Cathepsins and cystatins in extracellular fluids - useful biological markers in cancer
Janko Kos, Ana Schweiger, 2002, kratki znanstveni prispevek

Objavljeno v DiRROS: 31.01.2024; Ogledov: 93; Prenosov: 27
.pdf Celotno besedilo (59,57 KB)

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