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  1. Article: Enhanced Filtration Efficiency of Natural Materials with the Addition of Electrospun Poly(vinylidene fluoride-co-hexafluoropropylene) Fibres.

    Filipič, Gregor / Pirker, Luka / Krajnc, Anja Pogačnik / Ješelnik, Marjan / Remškar, Maja

    Materials (Basel, Switzerland)

    2023  Volume 16, Issue 6

    Abstract: Pollutants and infectious diseases can spread through air with airborne droplets and aerosols. A respiratory mask can decrease the amount of pollutants we inhale and it can protect us from airborne diseases. With the onset of the COVID-19 pandemic, masks ...

    Abstract Pollutants and infectious diseases can spread through air with airborne droplets and aerosols. A respiratory mask can decrease the amount of pollutants we inhale and it can protect us from airborne diseases. With the onset of the COVID-19 pandemic, masks became an everyday item used by a lot of people around the world. As most of them are for a single use, the amount of non-recyclable waste increased dramatically. The plastic from which the masks are made pollutes the environment with various chemicals and microplastic. Here, we investigated the time- and size-dependent filtration efficiency (FE) of aerosols in the range of 25.9 to 685.4 nm of five different natural materials whose FE was enhanced using electrospun poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF) fibres. A scanning electron microscope (SEM) was used to determine the morphology and structure of the natural materials as well as the thickness of the PVDF fibres, while the phase of the electrospun fibres was determined by Raman spectroscopy. A thin layer of the electrospun PVDF fibres with the same grammage was sandwiched between two sheets of natural materials, and their FE increased up to 80%. By varying the grammature of the electrospun polymer, we tuned the FE of cotton from 82.6 to 99.9%. Thus, through the optimization of the grammage of the electrospun polymer, the amount of plastic used in the process can be minimized, while achieving sufficiently high FE.
    Language English
    Publishing date 2023-03-14
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2487261-1
    ISSN 1996-1944
    ISSN 1996-1944
    DOI 10.3390/ma16062314
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Influence of crystal structure and oxygen vacancies on optical properties of nanostructured multi-stoichiometric tungsten suboxides.

    Višić, Bojana / Pirker, Luka / Opačić, Marko / Milosavljević, Ana / Lazarević, Nenad / Majaron, Boris / Remškar, Maja

    Nanotechnology

    2022  Volume 33, Issue 27

    Abstract: Four distinct tungsten suboxide ( ... ...

    Abstract Four distinct tungsten suboxide (WO
    Language English
    Publishing date 2022-04-20
    Publishing country England
    Document type Journal Article
    ZDB-ID 1362365-5
    ISSN 1361-6528 ; 0957-4484
    ISSN (online) 1361-6528
    ISSN 0957-4484
    DOI 10.1088/1361-6528/ac6316
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article: The Potential of Macroporous Silica-Nanocrystalline Cellulose Combination for Formulating Dry Emulsion Systems with Improved Flow Properties: A DoE Study.

    Pohlen, Mitja / Pirker, Luka / Dreu, Rok

    Pharmaceutics

    2021  Volume 13, Issue 8

    Abstract: The objective of this study was to explore the possible use of a new combination of two excipients, i.e., nanocrystalline cellulose (NCC) and macroporous silica (MS), as matrix materials for the compounding of dry emulsion systems and the effects these ... ...

    Abstract The objective of this study was to explore the possible use of a new combination of two excipients, i.e., nanocrystalline cellulose (NCC) and macroporous silica (MS), as matrix materials for the compounding of dry emulsion systems and the effects these two excipients have on the characteristics of dry emulsion powders produced by the spray drying process. A previously developed liquid O/W nanoemulsion, comprised of simvastatin, 1-oleoyl-rac-glycerol, Miglyol 812 and Tween 20, was employed. In order to comprehend the effects that these two matrix formers have on the spray drying process and on dry emulsion powder characteristics, alone and in combination, a DoE (Design of Experiment) approach was used. The physicochemical properties of dry emulsion samples were characterised by atomic force microscopy, scanning electron microscopy, mercury intrusion porosimetry, energy-dispersive X-ray spectroscopy and laser diffraction analysis. Additionally, total release and dissolution experiments were performed to assess drug release from multiple formulations. It was found that the macroporous silica matrix drastically improved flow properties of dry emulsion powders; however, it partially trapped the oil-drug mixture inside the pores and hindered complete release. NCC showed its potential to reduce oil entrapment in MS, but because of its rod-shaped particles deposited on the MS surface, powder flowability was deteriorated.
    Language English
    Publishing date 2021-07-30
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2527217-2
    ISSN 1999-4923
    ISSN 1999-4923
    DOI 10.3390/pharmaceutics13081177
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article: One-Step Plasma Synthesis of Nitrogen-Doped Carbon Nanomesh.

    Vesel, Alenka / Zaplotnik, Rok / Primc, Gregor / Pirker, Luka / Mozetič, Miran

    Nanomaterials (Basel, Switzerland)

    2021  Volume 11, Issue 4

    Abstract: A one-step method for plasma synthesis of nitrogen-doped carbon nanomesh is presented. The method involves a molten polymer, which is a source of carbon, and inductively coupled nitrogen plasma, which is a source of highly reactive nitrogen species. The ... ...

    Abstract A one-step method for plasma synthesis of nitrogen-doped carbon nanomesh is presented. The method involves a molten polymer, which is a source of carbon, and inductively coupled nitrogen plasma, which is a source of highly reactive nitrogen species. The method enables the deposition of the nanocarbon layer at a rate of almost 0.1 µm/s. The deposited nanocarbon is in the form of randomly oriented multilayer graphene nanosheets or nanoflakes with a thickness of several nm and an area of the order of 1000 nm
    Language English
    Publishing date 2021-03-25
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2662255-5
    ISSN 2079-4991
    ISSN 2079-4991
    DOI 10.3390/nano11040837
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Non-Destructive Low-Temperature Contacts to MoS

    Schock, Robin T K / Neuwald, Jonathan / Möckel, Wolfgang / Kronseder, Matthias / Pirker, Luka / Remškar, Maja / Hüttel, Andreas K

    Advanced materials (Deerfield Beach, Fla.)

    2023  Volume 35, Issue 13, Page(s) e2209333

    Abstract: Molybdenum disulfide nanoribbons and nanotubes are quasi-1D semiconductors with strong spin-orbit interaction, a nanomaterial highly promising for quantum electronic applications. Here, it is demonstrated that a bismuth semimetal layer between the ... ...

    Abstract Molybdenum disulfide nanoribbons and nanotubes are quasi-1D semiconductors with strong spin-orbit interaction, a nanomaterial highly promising for quantum electronic applications. Here, it is demonstrated that a bismuth semimetal layer between the contact metal and this nanomaterial strongly improves the properties of the contacts. Two-point resistances on the order of 100 kΩ are observed at room temperature. At cryogenic temperature, Coulomb blockade is visible. The resulting stability diagrams indicate a marked absence of trap states at the contacts and the corresponding disorder, compared to previous devices that use low-work-function metals as contacts. Single-level quantum transport is observed at temperatures below 100 mK.
    Language English
    Publishing date 2023-02-21
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 1474949-X
    ISSN 1521-4095 ; 0935-9648
    ISSN (online) 1521-4095
    ISSN 0935-9648
    DOI 10.1002/adma.202209333
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article: Synthesis and Characterization of Tungsten Suboxide W

    Pirker, Luka / Višić, Bojana / Kovač, Janez / Škapin, Srečo D / Remškar, Maja

    Nanomaterials (Basel, Switzerland)

    2021  Volume 11, Issue 8

    Abstract: ... ...

    Abstract W
    Language English
    Publishing date 2021-08-02
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2662255-5
    ISSN 2079-4991
    ISSN 2079-4991
    DOI 10.3390/nano11081985
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Single-Layer and Double-Layer Filtration Materials Based on Polyvinylidene Fluoride-Co-hexafluoropropylene Nanofibers Coated on Melamine Microfibers.

    Potisk, Tilen / Remškar, Maja / Pirker, Luka / Filipič, Gregor / Mihelič, Igor / Ješelnik, Marjan / Čoko, Urban / Ravnik, Miha

    ACS applied nano materials

    2023  Volume 6, Issue 17, Page(s) 15807–15819

    Abstract: In this work, we demonstrate selected optimization changes in the simple design of filtration masks to increase particle removal efficiency (PRE) and filter quality factor by combining experiments and numerical modeling. In particular, we focus on single- ...

    Abstract In this work, we demonstrate selected optimization changes in the simple design of filtration masks to increase particle removal efficiency (PRE) and filter quality factor by combining experiments and numerical modeling. In particular, we focus on single-layer filters fabricated from uniform thickness fibers and double-layer filters consisting of a layer of highly permeable thick fibers as a support and a thin layer of filtering electrospun nanofibers. For single-layer filters, we demonstrate performance improvement in terms of the quality factor by optimizing the geometry of the composition. We show significantly better PRE performance for filters composed of micrometer-sized fibers covered by a thin layer of electrospun nanofibers. This work is motivated and carried out in collaboration with a targeted industrial development of selected melamine-based filter nano- and micromaterials.
    Language English
    Publishing date 2023-08-22
    Publishing country United States
    Document type Journal Article
    ISSN 2574-0970
    ISSN (online) 2574-0970
    DOI 10.1021/acsanm.3c02592
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article: Nanoparticle exposure due to pyrotechnics during a football match

    Pirker, Luka / Gradišek, Anton / Višić, Bojana / Remškar, Maja

    Atmospheric environment. 2020 July 15, v. 233

    2020  

    Abstract: Use of pyrotechnic articles is a common, though forbidden practice at football matches. While the fans, especially the members of the ultras groups, view pyrotechnic displays as a part of their culture, these devices can be dangerous for the public. In ... ...

    Abstract Use of pyrotechnic articles is a common, though forbidden practice at football matches. While the fans, especially the members of the ultras groups, view pyrotechnic displays as a part of their culture, these devices can be dangerous for the public. In addition to the risks of burning, hand flares and similar items release toxic combustion by-products, including particulate matter – inhaling of which is harmful both for the spectators and players. In order to assess the amounts and composition of the aerosol particles released at a typical event, we performed a study using both a scanning mobility particle sizer and a low-pressure cascade impactor. The number concentration of nanoparticles was clearly correlated with the burning events. Several elements were identified in the collected samples, including heavy metals, while the majority of the sample consisted of amorphous carbon. The nanoparticle number concentration increased up to 12-fold immediately after the beginning of the flares burning, with the largest contribution of particles 155 nm in diameter. The cumulative dose the players inhaled during the match was around 7 × 10⁸ particles/kg, which is 300% higher than the dose one would get in a low-pollution environment. We discuss the results in view of similar pyrotechnical events, especially fireworks.
    Keywords aerosols ; carbon ; combustion ; environment ; particulates ; toxicity
    Language English
    Dates of publication 2020-0715
    Publishing place Elsevier Ltd
    Document type Article
    Note NAL-AP-2-clean
    ZDB-ID 216368-8
    ISSN 0004-6981 ; 1352-2310
    ISSN 0004-6981 ; 1352-2310
    DOI 10.1016/j.atmosenv.2020.117567
    Database NAL-Catalogue (AGRICOLA)

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  9. Article: Sterilization of polypropylene membranes of facepiece respirators by ionizing radiation

    Pirker, Luka / Krajnc, Anja Pogačnik / Malec, Jan / Radulović, Vladimir / Gradišek, Anton / Jelen, Andreja / Remškar, Maja / Mekjavić, Igor B / Kovač, Janez / Mozetič, Miran / Snoj, Luka

    Journal of membrane science. 2021 Feb. 01, v. 619

    2021  

    Abstract: Ionizing radiation has been identified as an option for sterilization of disposable filtering facepiece respirators in situations where the production of the respirators cannot keep up with demand. Gamma radiation and high energy electrons penetrate ... ...

    Abstract Ionizing radiation has been identified as an option for sterilization of disposable filtering facepiece respirators in situations where the production of the respirators cannot keep up with demand. Gamma radiation and high energy electrons penetrate deeply into the material and can be used to sterilize large batches of masks within a short time period. In relation to reports that sterilization by ionizing radiation reduces filtration efficiency of polypropylene membrane filters on account of static charge loss, we have demonstrated that both gamma and electron beam irradiation can be used for sterilization, provided that the respirators are recharged afterwards.
    Keywords energy ; filtration ; gamma radiation ; irradiation ; polypropylenes
    Language English
    Dates of publication 2021-0201
    Publishing place Elsevier B.V.
    Document type Article
    Note NAL-AP-2-clean
    ZDB-ID 194516-6
    ISSN 0376-7388
    ISSN 0376-7388
    DOI 10.1016/j.memsci.2020.118756
    Database NAL-Catalogue (AGRICOLA)

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  10. Article ; Online: A redispersible dry emulsion system with simvastatin prepared via fluid bed layering as a means of dissolution enhancement of a lipophilic drug.

    Pohlen, Mitja / Pirker, Luka / Luštrik, Matevž / Dreu, Rok

    International journal of pharmaceutics

    2018  Volume 549, Issue 1-2, Page(s) 325–334

    Abstract: The purpose of the study was to develop a redispersible dry emulsion, containing a lipophilic, poorly water soluble model drug simvastatin, by employing fluid bed coating technology. The presented dry emulsion manufacturing approach produces pellets in a ...

    Abstract The purpose of the study was to develop a redispersible dry emulsion, containing a lipophilic, poorly water soluble model drug simvastatin, by employing fluid bed coating technology. The presented dry emulsion manufacturing approach produces pellets in a way, where a layer of the dry emulsion is applied to a neutral core. In the preliminary formulation development phase 1-oleoyl-rac-glycerol was chosen as the oily lipid phase, based on the high drug solubility and potential bioavailability enhancement capability. Mannitol, HPMC and Tween 20 were selected as the solid carriers and surfactant, respectively. The design of experiments, specifically the mixture design approach, was used to obtain the optimal formulation composition. The emulsion reconstitution ability and stability were the main responses, used as the decisive parameters for formulation optimisation. Optimised formulations showed narrow droplet size distribution upon reconstitution, high stability, suitable drug loading and enhanced dissolution profile, compared to a non-lipid based tablet and the pure drug. The scanning electron microscopy, Raman spectroscopy and image analysis disclosed a uniform morphology of the applied layer with separated droplets with simvastatin and uniform size distribution and a circular shape of coated pellets. The study represents the proof of concept of designing redispersible dry emulsions using a fluid bed layering approach.
    MeSH term(s) Drug Carriers ; Drug Compounding ; Drug Liberation ; Emulsions ; Glycerides/chemistry ; Hydroxymethylglutaryl-CoA Reductase Inhibitors/chemistry ; Hypromellose Derivatives/chemistry ; Kinetics ; Mannitol/chemistry ; Particle Size ; Polysorbates/chemistry ; Proof of Concept Study ; Simvastatin/chemistry ; Solubility ; Surface Properties ; Surface-Active Agents/chemistry ; Technology, Pharmaceutical/methods
    Chemical Substances Drug Carriers ; Emulsions ; Glycerides ; Hydroxymethylglutaryl-CoA Reductase Inhibitors ; Polysorbates ; Surface-Active Agents ; Hypromellose Derivatives (3NXW29V3WO) ; Mannitol (3OWL53L36A) ; Simvastatin (AGG2FN16EV) ; 1-monooleoyl-rac-glycerol (D3AEF6S35P)
    Language English
    Publishing date 2018-08-01
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 428962-6
    ISSN 1873-3476 ; 0378-5173
    ISSN (online) 1873-3476
    ISSN 0378-5173
    DOI 10.1016/j.ijpharm.2018.07.064
    Database MEDical Literature Analysis and Retrieval System OnLINE

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