Iskanje po repozitoriju

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Ključne besede: SPOZNAJ, odprta znanost, Matlab, programski jezik, programsko okolje, uporabniški vmesnik
Objavljeno v DiRROS: 15.04.2025; Ogledov: 60; Prenosov: 18
Celotno besedilo (2,02 MB)
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Povzetek: There is an increasing concern about the management of municipal solid waste incineration bottom ash (BA), of which approximately 300,000 tons are generated annually in Finland. As an alternative to the landfilling of this waste, which is the most common practice in the industry, this study investigates the feasibility of upcycling BA for clay brick production. Here, kaolinitic and illitic clays were selected as the precursors. Kaolinitic or illitic clays containing 10, 20, and 30 wt% BA and their counterparts without BA were fired at 1000 ◦C. The materials and prepared bricks were characterized using X-ray diffraction, thermogravimetry, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, mass loss, visual appearance, linear shrinkage, water ab- sorption, apparent density, compressive strength, freeze–thaw, and leaching tests. The experimental results show that the incorporation of BA as an admixture positively influenced the properties of illitic clay-based bricks, which exhibited a reduction in cracks, mass loss, and water absorption while having higher apparent density, compressive strength, and residual strength than kaolinitic clay-based bricks. This is mainly ascribed to the difference in their sintering behavior and chemical and mineralogical composition; more notably, it is ascribed to the higher content of alkali oxides (K2O and Na2O) in the illitic clay than in the kaolinitic clay. The water ab- sorption of the bricks varied from 4 % to 25 %, and the compressive strength varied from 12 to 19 MPa depending on the BA content and clay type. Nevertheless, the compressive strength of all bricks satisfied the ASTM C62 standard for bricks subjected to negligible weathering, and the residual strength of some samples after exposure to 50 freeze–thaw cycles demonstrated their resistance to severe weathering. The dual effects of sintering and BA addition resulted in more stable crystalline phases and a densified microstructure. Moreover, the heavy metals in BA were encapsulated in kaolinitic and illitic clay bricks and satisfied EU regulations for inert and nonhazardous materials.
Ključne besede: municipality incineration ash, bricks, recycling
Objavljeno v DiRROS: 15.04.2025; Ogledov: 51; Prenosov: 17
Celotno besedilo (12,19 MB)
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Ključne besede: biodiversity, phytoplankton, zooplankton, expert group
Objavljeno v DiRROS: 15.04.2025; Ogledov: 52; Prenosov: 0
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Ključne besede: biodiversity, phytoplankton, zooplankton, expert group, Mediterranean Sea
Objavljeno v DiRROS: 15.04.2025; Ogledov: 44; Prenosov: 0
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Povzetek: The medically important immunosuppressant FK506 is a structurally complex macrolactone biosynthesized by a combined polyketide synthase and a nonribosomal peptide synthetase enzyme complex. Its acyltransferase domain 4 (AT4) selects an unusual extender unit, resulting in an allyl moiety on carbon 21 of the macrolactone backbone. Based on the AT4 domain, chemobiosynthetic processes have been developed that enable the introduction of diverse moieties at the carbon 21 position. However, the novel moieties that were introduced into the polyketide backbone are chemically inert. Reported here is a novel and efficient chemobiosynthetic approach that ensures high titer of an FK506 analogue containing a propargyl moiety. The novel FK506 analogue displays lower immunosuppression activity than FK506 with significantly reduced cytotoxicity. More importantly, the propargyl moiety contains a terminal alkyl group, which makes click chemistry reactions possible; this approach may potentially be translated to other medically important drugs of polyketide origin.
Objavljeno v DiRROS: 15.04.2025; Ogledov: 64; Prenosov: 10
Celotno besedilo (3,26 MB)