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Galimov AI, Kazanov DR, Poshakinskiy AV, Rakhlin MV, Eliseyev IA, Toropov AA, Remškar M, Shubina TV. Direct observation of split-mode exciton-polaritons in a single MoS 2 nanotube. Nanoscale Horiz 2024. [PMID: 38647350 DOI: 10.1039/d4nh00052h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
A single nanotube synthesized from a transition metal dichalcogenide (TMDC) exhibits strong exciton resonances and, in addition, can support optical whispering gallery modes. This combination is promising for observing exciton-polaritons without an external cavity. However, traditional energy-momentum-resolved detection methods are unsuitable for this tiny object. Instead, we propose to use split optical modes in a twisted nanotube with the flattened cross-section, where a gradually decreasing gap between the opposite walls leads to a change in mode energy, similar to the effect of the barrier width on the eigenenergies in the double-well potential. Using micro-reflectance spectroscopy, we investigated the rich pattern of polariton branches in single MoS2 tubes with both variable and constant gaps. Observed Rabi splitting in the 40-60 meV range is comparable to that for a MoS2 monolayer in a microcavity. Our results, based on the polariton dispersion measurements and polariton dynamics analysis, present a single TMDC nanotube as a perfect polaritonic structure for nanophotonics.
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Affiliation(s)
- A I Galimov
- Ioffe Institute, 26 Politekhnicheskaya, St. Petersburg, 194021, Russia.
| | - D R Kazanov
- Ioffe Institute, 26 Politekhnicheskaya, St. Petersburg, 194021, Russia.
| | - A V Poshakinskiy
- Ioffe Institute, 26 Politekhnicheskaya, St. Petersburg, 194021, Russia.
| | - M V Rakhlin
- Ioffe Institute, 26 Politekhnicheskaya, St. Petersburg, 194021, Russia.
| | - I A Eliseyev
- Ioffe Institute, 26 Politekhnicheskaya, St. Petersburg, 194021, Russia.
| | - A A Toropov
- Ioffe Institute, 26 Politekhnicheskaya, St. Petersburg, 194021, Russia.
| | - M Remškar
- Jozef Stefan Institute, 39 Jamova cesta, Ljubljana, 1000, Slovenia
| | - T V Shubina
- Ioffe Institute, 26 Politekhnicheskaya, St. Petersburg, 194021, Russia.
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2
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Potisk T, Remškar M, Pirker L, Filipič G, Mihelič I, Ješelnik M, Čoko U, Ravnik M. Single-Layer and Double-Layer Filtration Materials Based on Polyvinylidene Fluoride-Co-hexafluoropropylene Nanofibers Coated on Melamine Microfibers. ACS Appl Nano Mater 2023; 6:15807-15819. [PMID: 37706065 PMCID: PMC10496027 DOI: 10.1021/acsanm.3c02592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Accepted: 08/08/2023] [Indexed: 09/15/2023]
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.
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Affiliation(s)
- Tilen Potisk
- Laboratory
for Molecular Modeling, National Institute
of Chemistry, SI-1001 Ljubljana, Slovenia
- Faculty
of Mathematics and Physics, University of
Ljubljana, SI-1001 Ljubljana, Slovenia
| | - Maja Remškar
- Jožef
Stefan Institute, SI-1000 Ljubljana, Slovenia
| | - Luka Pirker
- Jožef
Stefan Institute, SI-1000 Ljubljana, Slovenia
- J. Heyrovsky
Institute of Physical Chemistry, Czech Academy
of Sciences, 182 23 Prague 8, Czech Republic
| | | | | | | | - Urban Čoko
- Laboratory
for Molecular Modeling, National Institute
of Chemistry, SI-1001 Ljubljana, Slovenia
- Faculty
of Mathematics and Physics, University of
Ljubljana, SI-1001 Ljubljana, Slovenia
| | - Miha Ravnik
- Faculty
of Mathematics and Physics, University of
Ljubljana, SI-1001 Ljubljana, Slovenia
- Jožef
Stefan Institute, SI-1000 Ljubljana, Slovenia
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3
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Conradi M, Podgornik B, Remškar M, Klobčar D, Kocijan A. Tribological Evaluation of Vegetable Oil/MoS 2 Nanotube-Based Lubrication of Laser-Textured Stainless Steel. Materials (Basel) 2023; 16:5844. [PMID: 37687537 PMCID: PMC10488841 DOI: 10.3390/ma16175844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 08/21/2023] [Accepted: 08/24/2023] [Indexed: 09/10/2023]
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.
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Affiliation(s)
- Marjetka Conradi
- Institute of Metals and Technology, Lepi Pot 11, 1000 Ljubljana, Slovenia; (B.P.); (A.K.)
| | - Bojan Podgornik
- Institute of Metals and Technology, Lepi Pot 11, 1000 Ljubljana, Slovenia; (B.P.); (A.K.)
| | - Maja Remškar
- Jozef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia;
| | - Damjan Klobčar
- Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva 6, 1000 Ljubljana, Slovenia;
| | - Aleksandra Kocijan
- Institute of Metals and Technology, Lepi Pot 11, 1000 Ljubljana, Slovenia; (B.P.); (A.K.)
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Filipič G, Pirker L, Krajnc AP, Ješelnik M, Remškar M. Enhanced Filtration Efficiency of Natural Materials with the Addition of Electrospun Poly(vinylidene fluoride-co-hexafluoropropylene) Fibres. Materials (Basel) 2023; 16:2314. [PMID: 36984195 PMCID: PMC10054789 DOI: 10.3390/ma16062314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 03/09/2023] [Accepted: 03/11/2023] [Indexed: 06/18/2023]
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.
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Affiliation(s)
- Gregor Filipič
- Jozef Stefan Institute, Jamova Cesta 39, 1000 Ljubljana, Slovenia
| | - Luka Pirker
- Jozef Stefan Institute, Jamova Cesta 39, 1000 Ljubljana, Slovenia
- Department of Electrochemical Materials, J. Heyrovsky Institute of Physical Chemistry, Dolejškova 3, 182 23 Prague, Czech Republic
| | - Anja Pogačnik Krajnc
- Jozef Stefan Institute, Jamova Cesta 39, 1000 Ljubljana, Slovenia
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska Ulica 19, 1000 Ljubljana, Slovenia
| | - Marjan Ješelnik
- smartMelamine d.o.o., Tomšičeva Cesta 9, 1330 Kočevje, Slovenia
| | - Maja Remškar
- Jozef Stefan Institute, Jamova Cesta 39, 1000 Ljubljana, Slovenia
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Schock RTK, Neuwald J, Möckel W, Kronseder M, Pirker L, Remškar M, Hüttel AK. Non-Destructive Low-Temperature Contacts to MoS 2 Nanoribbon and Nanotube Quantum Dots. Adv Mater 2023; 35:e2209333. [PMID: 36624967 DOI: 10.1002/adma.202209333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 12/15/2022] [Indexed: 06/17/2023]
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.
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Affiliation(s)
- Robin T K Schock
- Institute for Experimental and Applied Physics, University of Regensburg, 93040, Regensburg, Germany
| | - Jonathan Neuwald
- Institute for Experimental and Applied Physics, University of Regensburg, 93040, Regensburg, Germany
| | - Wolfgang Möckel
- Institute for Experimental and Applied Physics, University of Regensburg, 93040, Regensburg, Germany
| | - Matthias Kronseder
- Institute for Experimental and Applied Physics, University of Regensburg, 93040, Regensburg, Germany
| | - Luka Pirker
- Solid State Physics Department, Jožef Stefan Institute, 1000, Ljubljana, Slovenia
- J. Heyrovský Institute of Physical Chemistry, v.v.i., Czech Academy of Sciences, 182 23, Prague, Czech Republic
| | - Maja Remškar
- Solid State Physics Department, Jožef Stefan Institute, 1000, Ljubljana, Slovenia
| | - Andreas K Hüttel
- Institute for Experimental and Applied Physics, University of Regensburg, 93040, Regensburg, Germany
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Sterniša M, Gradišar Centa U, Drnovšek A, Remškar M, Smole Možina S. Pseudomonas fragi biofilm on stainless steel (at low temperatures) affects the survival of Campylobacter jejuni and Listeria monocytogenes and their control by a polymer molybdenum oxide nanocomposite coating. Int J Food Microbiol 2023; 394:110159. [PMID: 36924752 DOI: 10.1016/j.ijfoodmicro.2023.110159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 02/20/2023] [Accepted: 02/22/2023] [Indexed: 03/03/2023]
Abstract
Pseudomonas spp. are widely distributed bacteria on surfaces in the food production and processing environment, where they form extracellular polymeric substance rich biofilms that interact with other bacteria. In this study, the influence of biofilm of Pseudomonas fragi ATCC 4973 on Listeria monocytogenes ATCC 19115 and Campylobacter jejuni NCTC 11168 was investigated at 5 °C and 15 °C on stainless steel in broth and food homogenates (fish or chicken meat). Stainless steel was then coated with PVDF-HFP/PVP/MoO3 nanocomposite and examined for surface changes (scanning electron microscope, static contact angle, Vickers hardness and elastic modulus). The effect of the prepared nanocomposite coating on P. fragi and on L. monocytogenes and C. jejuni was evaluated in mono- and co-culture. P. fragi produced more biofilm at 15 °C than at 5 °C, especially when food homogenates were used as growth media. Co-cultivation with pathogens did not affect biofilm production by P. fragi, but significant changes were observed in L. monocytogenes and C. jejuni, resulting in a decrease and increase, respectively, in the determined number of culturable biofilm cells. The first change was probably due to competition for the surface, and the second to the oxygen gradient. Stainless steel was then coated with a PVDF-HFP/PVP/MoO3 nanocomposite, which was characterised by lower roughness and higher wettability, but lower hardness compared to uncoated stainless steel. The prepared nanocoating showed bactericidal activity when tested in phosphate buffered saline. When used in food homogenates, a reduction of over 95 % in bacterial counts was observed. An abundant biofilm of P. fragi proved protective to L. monocytogenes and C. jejuni against the functionalised nanocomposite surface when tested in food homogenates. The control of spoilage Pseudomonas spp., which are common in the food production and processing environment, is important for reducing the contamination of food with spoilage bacteria and with pathogens such as L. monocytogenes and C. jejuni, which may be present in the same environment. The PVDF-HFP/PVP/MoO3 nanocomposite showed good potential for use as a coating for food contact surfaces, but possible migration of nanoparticles from the nanocomposite coating to food should be evaluated before its commercial use.
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Affiliation(s)
- Meta Sterniša
- Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana, Slovenia.
| | - Urška Gradišar Centa
- Condensed Matter Physics Department, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia; Laboratory for Experimental Mechanics, Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva 6, 1000 Ljubljana, Slovenia
| | - Aljaž Drnovšek
- Department of Thin Films and Surfaces, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
| | - Maja Remškar
- Condensed Matter Physics Department, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
| | - Sonja Smole Možina
- Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana, Slovenia
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Višić B, Pirker L, Opačić M, Milosavljević A, Lazarević N, Majaron B, Remškar M. Influence of crystal structure and oxygen vacancies on optical properties of nanostructured multi-stoichiometric tungsten suboxides. Nanotechnology 2022; 33:275705. [PMID: 35358963 DOI: 10.1088/1361-6528/ac6316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 03/31/2022] [Indexed: 06/14/2023]
Abstract
Four distinct tungsten suboxide (WO3-x) nanomaterials were synthesized via chemical vapour transport reaction and the role of their crystal structures on the optical properties was studied. These materials grow either as thin, quasi-2D crystals with the WnO3n-1formula (in shape of platelets or nanotiles), or as nanowires (W5O14, W18O49). For the quasi-2D materials, the appearance of defect states gives rise to two indirect absorption edges. One is assigned to the regular bandgap occurring between the valence and the conduction band, while the second is a defect-induced band. While the bandgap values of platelets and nanotiles are in the upper range of the reported values for the suboxides, the nanowires' bandgaps are lower due to the higher number of free charge carriers. Both types of nanowires sustain localized surface plasmon resonances, as evidenced from the extinction measurements, whereas the quasi-2D materials exhibit excitonic transitions. All four materials have photoluminescence emission peaks in the UV region. The interplay of the crystal structure, oxygen vacancies and shape can result in changes in optical behaviour, and the understanding of these effects could enable intentional tuning of selected properties.
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Affiliation(s)
- Bojana Višić
- Department of Condensed Matter Physics, Jozef Stefan Institute, Jamova Cesta 39, 1000 Ljubljana, Slovenia
- Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia
| | - Luka Pirker
- Department of Condensed Matter Physics, Jozef Stefan Institute, Jamova Cesta 39, 1000 Ljubljana, Slovenia
| | - Marko Opačić
- Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia
| | - Ana Milosavljević
- Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia
| | - Nenad Lazarević
- Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia
| | - Boris Majaron
- Department of Complex Matter, Jozef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
- Faculty of Physics and Mathematics, University of Ljubljana, Jadranska 19, Slovenia
| | - Maja Remškar
- Department of Condensed Matter Physics, Jozef Stefan Institute, Jamova Cesta 39, 1000 Ljubljana, Slovenia
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Pirker L, Višić B, Kovač J, Škapin SD, Remškar M. Synthesis and Characterization of Tungsten Suboxide W nO 3n-1 Nanotiles. Nanomaterials (Basel) 2021; 11:nano11081985. [PMID: 34443817 PMCID: PMC8398204 DOI: 10.3390/nano11081985] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 07/30/2021] [Accepted: 07/30/2021] [Indexed: 11/16/2022]
Abstract
WnO3n-1 nanotiles, with multiple stoichiometries within one nanotile, were synthesized via the chemical vapour transport method. They grow along the [010] crystallographic axis, with the thickness ranging from a few tens to a few hundreds of nm, with the lateral size up to several µm. Distinct surface corrugations, up to a few 10 nm deep appear during growth. The {102}r crystallographic shear planes indicate the WnO3n-1 stoichiometries. Within a single nanotile, six stoichiometries were detected, namely W16O47 (WO2.938), W15O44 (WO2.933), W14O41 (WO2.928), W13O38 (WO2.923), W12O35 (WO2.917), and W11O32 (WO2.909), with the last three never being reported before. The existence of oxygen vacancies within the crystallographic shear planes resulted in the observed non-zero density of states at the Fermi energy.
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Affiliation(s)
- Luka Pirker
- Jožef Stefan Institute, Jamova Cesta 39, 1000 Ljubljana, Slovenia; (L.P.); (J.K.); (S.D.Š.); (M.R.)
| | - Bojana Višić
- Jožef Stefan Institute, Jamova Cesta 39, 1000 Ljubljana, Slovenia; (L.P.); (J.K.); (S.D.Š.); (M.R.)
- Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia
- Correspondence:
| | - Janez Kovač
- Jožef Stefan Institute, Jamova Cesta 39, 1000 Ljubljana, Slovenia; (L.P.); (J.K.); (S.D.Š.); (M.R.)
| | - Srečo D. Škapin
- Jožef Stefan Institute, Jamova Cesta 39, 1000 Ljubljana, Slovenia; (L.P.); (J.K.); (S.D.Š.); (M.R.)
| | - Maja Remškar
- Jožef Stefan Institute, Jamova Cesta 39, 1000 Ljubljana, Slovenia; (L.P.); (J.K.); (S.D.Š.); (M.R.)
- Faculty for Mathematics and Physics, University of Ljubljana, Jadranska Ulica 19, 1000 Ljubljana, Slovenia
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Pogačnik Krajnc A, Pirker L, Gradišar Centa U, Gradišek A, Mekjavic IB, Godnič M, Čebašek M, Bregant T, Remškar M. Size- and Time-Dependent Particle Removal Efficiency of Face Masks and Improvised Respiratory Protection Equipment Used during the COVID-19 Pandemic. Sensors (Basel) 2021; 21:1567. [PMID: 33668141 PMCID: PMC7956512 DOI: 10.3390/s21051567] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/16/2021] [Accepted: 02/20/2021] [Indexed: 12/21/2022]
Abstract
Size- and time-dependent particle removal efficiency (PRE) of different protective respiratory masks were determined using a standard aerosol powder with the size of particles in the range of an uncoated SARS-CoV-2 virus and small respiratory droplets. Number concentration of particles was measured by a scanning mobility particle sizer. Respiratory protective half-masks, surgical masks, and cotton washable masks were tested. The results show high filtration efficiency of FFP2, FFP3, and certified surgical masks for all sizes of tested particles, while protection efficiency of washable masks depends on their constituent fabrics. Measurements showed decreasing PRE of all masks over time due to transmission of nanoparticles through the mask-face interface. On the other hand, the PRE of the fabric is governed by deposition of the aerosols, consequently increasing the PRE.
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Affiliation(s)
- Anja Pogačnik Krajnc
- Jožef Stefan Institute, Jamova Cesta 39, 1000 Ljubljana, Slovenia; (A.P.K.); (U.G.C.); (A.G.); (I.B.M.); (M.R.)
| | - Luka Pirker
- Jožef Stefan Institute, Jamova Cesta 39, 1000 Ljubljana, Slovenia; (A.P.K.); (U.G.C.); (A.G.); (I.B.M.); (M.R.)
| | - Urška Gradišar Centa
- Jožef Stefan Institute, Jamova Cesta 39, 1000 Ljubljana, Slovenia; (A.P.K.); (U.G.C.); (A.G.); (I.B.M.); (M.R.)
| | - Anton Gradišek
- Jožef Stefan Institute, Jamova Cesta 39, 1000 Ljubljana, Slovenia; (A.P.K.); (U.G.C.); (A.G.); (I.B.M.); (M.R.)
| | - Igor B. Mekjavic
- Jožef Stefan Institute, Jamova Cesta 39, 1000 Ljubljana, Slovenia; (A.P.K.); (U.G.C.); (A.G.); (I.B.M.); (M.R.)
| | - Matej Godnič
- Novo Mesto General Hospital, Šmihelska Cesta 1, 8000 Novo Mesto, Slovenia;
| | - Metod Čebašek
- HYLA d.o.o., Brnčičeva Ulica 47, 1231 Ljubljana, Slovenia;
| | | | - Maja Remškar
- Jožef Stefan Institute, Jamova Cesta 39, 1000 Ljubljana, Slovenia; (A.P.K.); (U.G.C.); (A.G.); (I.B.M.); (M.R.)
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska Cesta 19, 1000 Ljubljana, Slovenia
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Pirker L, Krajnc AP, Malec J, Radulović V, Gradišek A, Jelen A, Remškar M, Mekjavić IB, Kovač J, Mozetič M, Snoj L. Sterilization of polypropylene membranes of facepiece respirators by ionizing radiation. J Memb Sci 2021; 619:118756. [PMID: 33024349 PMCID: PMC7528844 DOI: 10.1016/j.memsci.2020.118756] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 08/28/2020] [Accepted: 08/31/2020] [Indexed: 11/24/2022]
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.
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Affiliation(s)
- Luka Pirker
- Jožef Stefan Institute, Jamova Cesta 39, 1000, Ljubljana, Slovenia
| | | | - Jan Malec
- Jožef Stefan Institute, Jamova Cesta 39, 1000, Ljubljana, Slovenia
| | | | - Anton Gradišek
- Jožef Stefan Institute, Jamova Cesta 39, 1000, Ljubljana, Slovenia
| | - Andreja Jelen
- Jožef Stefan Institute, Jamova Cesta 39, 1000, Ljubljana, Slovenia
| | - Maja Remškar
- Jožef Stefan Institute, Jamova Cesta 39, 1000, Ljubljana, Slovenia
| | - Igor B Mekjavić
- Jožef Stefan Institute, Jamova Cesta 39, 1000, Ljubljana, Slovenia
| | - Janez Kovač
- Jožef Stefan Institute, Jamova Cesta 39, 1000, Ljubljana, Slovenia
| | - Miran Mozetič
- Jožef Stefan Institute, Jamova Cesta 39, 1000, Ljubljana, Slovenia
| | - Luka Snoj
- Jožef Stefan Institute, Jamova Cesta 39, 1000, Ljubljana, Slovenia
- University of Ljubljana, Faculty of Mathematics and Physics, Jadranska Ulica 19, 1000, Ljubljana, Slovenia
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Lukežič T, Pikl Š, Zaburannyi N, Remškar M, Petković H, Müller R. Heterologous expression of the atypical tetracycline chelocardin reveals the full set of genes required for its biosynthesis. Microb Cell Fact 2020; 19:230. [PMID: 33341113 PMCID: PMC7749508 DOI: 10.1186/s12934-020-01495-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 12/05/2020] [Indexed: 12/02/2022] Open
Abstract
Background Chelocardin (CHD) exhibits a broad-spectrum antibiotic activity and showed promising results in a small phase II clinical study conducted on patients with urinary tract infections. Importantly, CHD was shown to be active also against tetracycline-resistant Gram-negative pathogens, which is gaining even more importance in today’s antibiotic crisis. We have demonstrated that modifications of CHD through genetic engineering of its producer, the actinomycete Amycolatopsis sulphurea, are not only possible but yielded even more potent antibiotics than CHD itself, like 2-carboxamido-2-deacetyl-chelocardin (CD-CHD), which is currently in preclinical evaluation. A. sulphurea is difficult to genetically manipulate and therefore manipulation of the chd biosynthetic gene cluster in a genetically amenable heterologous host would be of high importance for further drug-discovery efforts. Results We report heterologous expression of the CHD biosynthetic gene cluster in the model organism Streptomyces albus del14 strain. Unexpectedly, we found that the originally defined CHD gene cluster fails to provide all genes required for CHD formation, including an additional cyclase and two regulatory genes. Overexpression of the putative pathway-specific streptomyces antibiotic regulatory protein chdB in A. sulphurea resulted in an increase of both, CHD and CD-CHD production. Applying a metabolic-engineering approach, it was also possible to generate the potent CHD analogue, CD-CHD in S. albus. Finally, an additional yield increase was achieved in S. albus del14 by in-trans overexpression of the chdR exporter gene, which provides resistance to CHD and CDCHD. Conclusions We identified previously unknown genes in the CHD cluster, which were shown to be essential for chelocardin biosynthesis by expression of the full biosynthetic gene cluster in S. albus as heterologous host. When comparing to oxytetracycline biosynthesis, we observed that the CHD gene cluster contains additional enzymes not found in gene clusters encoding the biosynthesis of typical tetracyclines (such as oxytetracycline). This finding probably explains the different chemistries and modes of action, which make CHD/CD-CHD valuable lead structures for clinical candidates. Even though the CHD genes are derived from a rare actinomycete A. sulphurea, the yield of CHD in the heterologous host was very good. The corrected nucleotide sequence of the CHD gene cluster now contains all gene products required for the production of CHD in a genetically amenable heterologous host, thus opening new possibilities towards production of novel and potent tetracycline analogues with a new mode of action.
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Affiliation(s)
- Tadeja Lukežič
- Department of Microbial Natural Products, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS)-Helmholtz Centre for Infection Research (HZI), and Department of Pharmacy, Saarland University Campus, Campus E8.1, 66123, Saarbrücken, Germany.,German Center for Infection Research (DZIF), Partner Site Hannover-Braunschweig, 38124, Braunschweig, Germany.,National Institute of Biology, Večna pot 111, 1000, Ljubljana, Slovenia
| | - Špela Pikl
- Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000, Ljubljana, Slovenia
| | - Nestor Zaburannyi
- Department of Microbial Natural Products, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS)-Helmholtz Centre for Infection Research (HZI), and Department of Pharmacy, Saarland University Campus, Campus E8.1, 66123, Saarbrücken, Germany.,German Center for Infection Research (DZIF), Partner Site Hannover-Braunschweig, 38124, Braunschweig, Germany
| | - Maja Remškar
- Department of Microbial Natural Products, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS)-Helmholtz Centre for Infection Research (HZI), and Department of Pharmacy, Saarland University Campus, Campus E8.1, 66123, Saarbrücken, Germany.,German Center for Infection Research (DZIF), Partner Site Hannover-Braunschweig, 38124, Braunschweig, Germany
| | - Hrvoje Petković
- Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000, Ljubljana, Slovenia.
| | - Rolf Müller
- Department of Microbial Natural Products, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS)-Helmholtz Centre for Infection Research (HZI), and Department of Pharmacy, Saarland University Campus, Campus E8.1, 66123, Saarbrücken, Germany. .,German Center for Infection Research (DZIF), Partner Site Hannover-Braunschweig, 38124, Braunschweig, Germany.
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12
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Božinović K, Nestić D, Centa UG, Ambriović-Ristov A, Dekanić A, de Bisschop L, Remškar M, Majhen D. In-vitro toxicity of molybdenum trioxide nanoparticles on human keratinocytes. Toxicology 2020; 444:152564. [DOI: 10.1016/j.tox.2020.152564] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 08/14/2020] [Accepted: 08/22/2020] [Indexed: 12/14/2022]
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13
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Liu M, Wei S, Shahi S, Jaiswal HN, Paletti P, Fathipour S, Remškar M, Jiao J, Hwang W, Yao F, Li H. Enhanced carrier transport by transition metal doping in WS 2 field effect transistors. Nanoscale 2020; 12:17253-17264. [PMID: 32329484 DOI: 10.1039/d0nr01573c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
High contact resistance is one of the primary concerns for electronic device applications of two-dimensional (2D) layered semiconductors. Here, we explore the enhanced carrier transport through metal-semiconductor interfaces in WS2 field effect transistors (FETs) by introducing a typical transition metal, Cu, with two different doping strategies: (i) a "generalized" Cu doping by using randomly distributed Cu atoms along the channel and (ii) a "localized" Cu doping by adapting an ultrathin Cu layer at the metal-semiconductor interface. Compared to the pristine WS2 FETs, both the generalized Cu atomic dopant and localized Cu contact decoration can provide a Schottky-to-Ohmic contact transition owing to the reduced contact resistances by 1-3 orders of magnitude, and consequently elevate electron mobilities by 5-7 times. Our work demonstrates that the introduction of transition metal can be an efficient and reliable technique to enhance the carrier transport and device performance in 2D TMD FETs.
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Affiliation(s)
- Maomao Liu
- Department of Electrical Engineering, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA.
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14
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Pirker L, Višić B, Škapin SD, DraŽić G, Kovač J, Remškar M. Multi-stoichiometric quasi-two-dimensional W nO 3n-1 tungsten oxides. Nanoscale 2020; 12:15102-15114. [PMID: 32644095 DOI: 10.1039/d0nr02014a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Quasi-two-dimensional tungsten oxide structures, which nucleate by epitaxial growth on W19O55 nanowires (NW) and grow as thin platelets, were identified. Both the nanowires and the platelets accommodate oxygen deficiency by the formation of crystallographic shear planes. Stoichiometric phases, W18O53 (WO2.944), W17O50 (WO2.941), W16O47 (WO2.938), W15O44 (WO2.933), W14O41 (WO2.929), W10O29 (WO2.9), and W9O26 (WO2.889), syntactically grow inside a single platelet. These layered crystals show a new kind of polycrystallinity, where crystallographic shear planes accommodate oxygen deficiency and at the same time stabilize this multi-stoichiometric structure.
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Affiliation(s)
- Luka Pirker
- JoŽef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia.
| | - Bojana Višić
- JoŽef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia. and Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia
| | - Srečo D Škapin
- JoŽef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia. and JoŽef Stefan International Postgraduate School, Jamova cesta 39, 1000 Ljubljana, Slovenia
| | - Goran DraŽić
- JoŽef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia. and JoŽef Stefan International Postgraduate School, Jamova cesta 39, 1000 Ljubljana, Slovenia and National Institute of Chemistry, Hajdrihova 19, 1001 Ljubljana, Slovenia
| | - Janez Kovač
- JoŽef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia.
| | - Maja Remškar
- JoŽef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia.
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Zheng F, Pozzi G, Migunov V, Pirker L, Remškar M, Beleggia M, Dunin-Borkowski RE. Quantitative measurement of charge accumulation along a quasi-one-dimensional W 5O 14 nanowire during electron field emission. Nanoscale 2020; 12:10559-10564. [PMID: 32162633 DOI: 10.1039/d0nr00739k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We use an electron holographic method to determine the charge distribution along a quasi-one-dimensional W5O14 nanowire during in situ field emission in a transmission electron microscope. The results show that the continuous charge distribution along the nanowire is not linear, but that there is an additional accumulation of charge at its apex. An analytical expression for this additional contribution to the charge distribution is proposed and its effect on the field enhancement factor and emission current is discussed.
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Affiliation(s)
- Fengshan Zheng
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany.
| | - Giulio Pozzi
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany. and Department of Physics and Astronomy, University of Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy
| | - Vadim Migunov
- Central Facility for Electron Microscopy (GFE), RWTH Aachen University, Ahornstrasse 55, 52074 Aachen, Germany
| | - Luka Pirker
- Jozef Stefan Institute, Solid-State Physics Department, Jamova 39, SLO-1000 Ljubljana, Slovenia
| | - Maja Remškar
- Jozef Stefan Institute, Solid-State Physics Department, Jamova 39, SLO-1000 Ljubljana, Slovenia
| | - Marco Beleggia
- DTU Nanolab, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Rafal E Dunin-Borkowski
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany.
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16
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Olatunji S, Yu X, Bailey J, Huang CY, Zapotoczna M, Bowen K, Remškar M, Müller R, Scanlan EM, Geoghegan JA, Olieric V, Caffrey M. Structures of lipoprotein signal peptidase II from Staphylococcus aureus complexed with antibiotics globomycin and myxovirescin. Nat Commun 2020; 11:140. [PMID: 31919415 PMCID: PMC6952399 DOI: 10.1038/s41467-019-13724-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 11/20/2019] [Indexed: 01/22/2023] Open
Abstract
Antimicrobial resistance is a major global threat that calls for new antibiotics. Globomycin and myxovirescin are two natural antibiotics that target the lipoprotein-processing enzyme, LspA, thereby compromising the integrity of the bacterial cell envelope. As part of a project aimed at understanding their mechanism of action and for drug development, we provide high-resolution crystal structures of the enzyme from the human pathogen methicillin-resistant Staphylococcus aureus (MRSA) complexed with globomycin and with myxovirescin. Our results reveal an instance of convergent evolution. The two antibiotics possess different molecular structures. Yet, they appear to inhibit identically as non-cleavable tetrahedral intermediate analogs. Remarkably, the two antibiotics superpose along nineteen contiguous atoms that interact similarly with LspA. This 19-atom motif recapitulates a part of the substrate lipoprotein in its proposed binding mode. Incorporating this motif into a scaffold with suitable pharmacokinetic properties should enable the development of effective antibiotics with built-in resistance hardiness. The enzyme LspA from the human pathogen Staphylococcus aureus (MRSA) contributes to the integrity and function of the bacterial cell envelope. Here, authors provide crystal structures of LspA in complex with two natural antibiotics, which have profoundly different structures but inhibit LspA in an identical way.
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Affiliation(s)
- Samir Olatunji
- Membrane Structural and Functional Biology Group, School of Medicine and School of Biochemistry and Immunology, Trinity College Dublin, Dublin, D02 R590, Ireland
| | - Xiaoxiao Yu
- Membrane Structural and Functional Biology Group, School of Medicine and School of Biochemistry and Immunology, Trinity College Dublin, Dublin, D02 R590, Ireland
| | - Jonathan Bailey
- Membrane Structural and Functional Biology Group, School of Medicine and School of Biochemistry and Immunology, Trinity College Dublin, Dublin, D02 R590, Ireland
| | - Chia-Ying Huang
- Swiss Light Source, Paul Scherrer Institute, CH-5232, Villigen, Switzerland
| | - Marta Zapotoczna
- Moyne Institute of Preventive Medicine, Department of Microbiology, School of Genetics and Microbiology, Trinity College Dublin, Dublin, D02, Ireland
| | - Katherine Bowen
- School of Chemistry, Trinity College Dublin, Dublin, D02 R590, Ireland
| | - Maja Remškar
- Department Microbial Natural Products, Helmholtz-Institute for Pharmaceutical Research Saarland, Helmholtz Centre for Infection Research and Department of Pharmacy, Saarland University Campus E8 1, D-66123, Saarbrücken, Germany
| | - Rolf Müller
- Department Microbial Natural Products, Helmholtz-Institute for Pharmaceutical Research Saarland, Helmholtz Centre for Infection Research and Department of Pharmacy, Saarland University Campus E8 1, D-66123, Saarbrücken, Germany
| | - Eoin M Scanlan
- School of Chemistry, Trinity College Dublin, Dublin, D02 R590, Ireland
| | - Joan A Geoghegan
- Moyne Institute of Preventive Medicine, Department of Microbiology, School of Genetics and Microbiology, Trinity College Dublin, Dublin, D02, Ireland
| | - Vincent Olieric
- Swiss Light Source, Paul Scherrer Institute, CH-5232, Villigen, Switzerland
| | - Martin Caffrey
- Membrane Structural and Functional Biology Group, School of Medicine and School of Biochemistry and Immunology, Trinity College Dublin, Dublin, D02 R590, Ireland.
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Hug JJ, Bader CD, Remškar M, Cirnski K, Müller R. Concepts and Methods to Access Novel Antibiotics from Actinomycetes. Antibiotics (Basel) 2018; 7:E44. [PMID: 29789481 PMCID: PMC6022970 DOI: 10.3390/antibiotics7020044] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 05/14/2018] [Accepted: 05/17/2018] [Indexed: 12/25/2022] Open
Abstract
Actinomycetes have been proven to be an excellent source of secondary metabolites for more than half a century. Exhibiting various bioactivities, they provide valuable approved drugs in clinical use. Most microorganisms are still untapped in terms of their capacity to produce secondary metabolites, since only a small fraction can be cultured in the laboratory. Thus, improving cultivation techniques to extend the range of secondary metabolite producers accessible under laboratory conditions is an important first step in prospecting underexplored sources for the isolation of novel antibiotics. Currently uncultured actinobacteria can be made available by bioprospecting extreme or simply habitats other than soil. Furthermore, bioinformatic analysis of genomes reveals most producers to harbour many more biosynthetic gene clusters than compounds identified from any single strain, which translates into a silent biosynthetic potential of the microbial world for the production of yet unknown natural products. This review covers discovery strategies and innovative methods recently employed to access the untapped reservoir of natural products. The focus is the order of actinomycetes although most approaches are similarly applicable to other microbes. Advanced cultivation methods, genomics- and metagenomics-based approaches, as well as modern metabolomics-inspired methods are highlighted to emphasise the interplay of different disciplines to improve access to novel natural products.
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Affiliation(s)
- Joachim J Hug
- Department Microbial Natural Products, Helmholtz-Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research (HZI) and Department of Pharmacy, Saarland University, Campus E8.1, 66123 Saarbrücken, Germany.
- German Center for Infection Research (DZIF), Partner Site Hannover-Braunschweig, 38124 Braunschweig, Germany.
| | - Chantal D Bader
- Department Microbial Natural Products, Helmholtz-Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research (HZI) and Department of Pharmacy, Saarland University, Campus E8.1, 66123 Saarbrücken, Germany.
- German Center for Infection Research (DZIF), Partner Site Hannover-Braunschweig, 38124 Braunschweig, Germany.
| | - Maja Remškar
- Department Microbial Natural Products, Helmholtz-Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research (HZI) and Department of Pharmacy, Saarland University, Campus E8.1, 66123 Saarbrücken, Germany.
- German Center for Infection Research (DZIF), Partner Site Hannover-Braunschweig, 38124 Braunschweig, Germany.
| | - Katarina Cirnski
- Department Microbial Natural Products, Helmholtz-Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research (HZI) and Department of Pharmacy, Saarland University, Campus E8.1, 66123 Saarbrücken, Germany.
- German Center for Infection Research (DZIF), Partner Site Hannover-Braunschweig, 38124 Braunschweig, Germany.
| | - Rolf Müller
- Department Microbial Natural Products, Helmholtz-Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research (HZI) and Department of Pharmacy, Saarland University, Campus E8.1, 66123 Saarbrücken, Germany.
- German Center for Infection Research (DZIF), Partner Site Hannover-Braunschweig, 38124 Braunschweig, Germany.
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Lang A, Ovsenik M, Verdenik I, Remškar M, Oblak Č. Nanoparticle concentrations and composition in a dental office and dental laboratory: A pilot study on the influence of working procedures. J Occup Environ Hyg 2018; 15:441-447. [PMID: 29370575 DOI: 10.1080/15459624.2018.1432864] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
During material treatment in dentistry particles of different size are released in the air. To examine the degree of particle exposure, air scanning to dental employees was performed by the Scanning Mobility Particle Sizer. The size, shape and chemical composition of particles collected with a low-pressure impactor were determined by scanning electronic microscopy and X-ray dispersive analysis. The average concentrations of nanoparticles during working periods in a clean dental laboratory (45,000-56,000 particles/cm3), in an unclean dental laboratory (28,000-74,000 particles/cm3), and in a dental office (21,000-50,000 particles/cm3), were significantly higher compared to average concentrations during nonworking periods in the clean dental laboratory (11,000-24,000 particles/cm3), unclean laboratory (14,000-40,000 particles/cm3), and dental office (13,000-26,000 particles/cm3). Peak concentration of nanoparticles in work-intensive periods were found significantly higher (up to 773,000 particles/cm3), compared to the non-working periods (147,000 particles/cm3) and work-less intensive periods (365,000 particles/cm3). The highest mass concentration value ranged from 0.055-0.166 mg/m3. X-ray dispersive analysis confirmed the presence of carbon, potassium, oxygen, iron, aluminum, zinc, silicon, and phosphorus as integral elements of dental restorative materials in form of nanoparticle clusters, all smaller than 100 nm. We concluded that dental employees are exposed to nanoparticles in their working environment and are therefore potentially at risk for certain respiratory and systematic diseases.
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Affiliation(s)
- Andreja Lang
- a Faculty of Medicine , University of Ljubljana , Ljubljana , Slovenia
| | - Maja Ovsenik
- b Department of Orthodontics and Jaw Orthopaedics, Faculty of Medicine , University of Ljubljana , Ljubljana , Slovenia
| | - Ivan Verdenik
- c Department of Obstetrics and Gynecology , University Medical Center , Ljubljana , Slovenia
| | - Maja Remškar
- d Solid-State Physics Department , Josef Stefan Institute , Ljubljana , Slovenia
| | - Čedomir Oblak
- e Department of Prosthodontics, Faculty of Medicine , University of Ljubljana , Ljubljana , Slovenia
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Rodríguez Ripoll M, Tomala A, Gabler C, DraŽić G, Pirker L, Remškar M. In situ tribochemical sulfurization of molybdenum oxide nanotubes. Nanoscale 2018; 10:3281-3290. [PMID: 29384160 DOI: 10.1039/c7nr05830f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
MoS2 nanoparticles are typically obtained by high temperature sulfurization of organic and inorganic precursors under a S rich atmosphere and have excellent friction reduction properties. We present a novel approach for making the sulfurization unnecessary for MoO3 nanotubes during the synthesis process for friction and wear reduction applications while simultaneously achieving a superb tribological performance. To this end, we report the first in situ sulfurization of MoO3 nanotubes during sliding contact in the presence of sulfur-containing lubricant additives. The sulfurization leads to the tribo-chemical formation of a MoS2-rich low-friction tribofilm as verified using Raman spectroscopy and can be achieved both during sliding contact and under extreme pressure conditions. Under sliding contact conditions, MoO3 nanotubes in synergy with sulfurized olefin polysulfide and pre-formed zinc dialkyl dithiophosphate tribofilms achieve an excellent friction performance. Under these conditions, the tribochemical sulfurization of MoO3 nanotubes leads to a similar coefficient of friction to the one obtained using a model nanolubricant containing MoS2 nanotubes. Under extreme pressure conditions, the in situ sulfurization of MoO3 nanotubes using sulfurized olefin polysulfide results in a superb load carrying capacity capable of outperforming MoS2 nanotubes. The reason is that while MoO3 nanotubes are able to continuously sulfurize during sliding contact conditions, MoS2 nanotubes progressively degrade by oxidation thus losing lubricity.
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Affiliation(s)
| | - Agnieszka Tomala
- AC2T research GmbH, Wiener Neustadt, Austria. and Institute for Sustainable Technologies, Radom, Poland
| | | | - Goran DraŽić
- National Institute of Chemistry, Ljubljana, Slovenia and Institute JoŽef Stefan, Ljubljana, Slovenia
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Varlec A, Eršte A, Bobnar V, Remškar M. Influence of preparation conditions on structural and dielectric properties of PVDF–MoS2 nanotubes composite films. J Polym Res 2016. [DOI: 10.1007/s10965-016-0930-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Imani R, Drašler B, Kononenko V, Romih T, Eleršič K, Jelenc J, Junkar I, Remškar M, Drobne D, Kralj-Iglič V, Iglič A. Growth of a Novel Nanostructured ZnO Urchin: Control of Cytotoxicity and Dissolution of the ZnO Urchin. Nanoscale Res Lett 2015; 10:441. [PMID: 26573932 PMCID: PMC4646880 DOI: 10.1186/s11671-015-1145-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 11/05/2015] [Indexed: 06/05/2023]
Abstract
The applications of zinc oxide (ZnO) nanowires (NWs) in implantable wireless devices, such as diagnostic nanobiosensors and nanobiogenerators, have recently attracted enormous attention due to their unique properties. However, for these implantable nanodevices, the biocompatibility and the ability to control the behaviour of cells in contact with ZnO NWs are demanded for the success of these implantable devices, but to date, only a few contrasting results from their biocompatibility can be found. There is a need for more research about the biocompatibility of ZnO nanostructures and the adhesion and viability of cells on the surface of ZnO nanostructures. Here, we introduce synthesis of a new nature-inspired nanostructured ZnO urchin, with the dimensions of the ZnO urchin's acicula being controllable. To examine the biocompatibility and behaviour of cells in contact with the ZnO urchin, the Madin-Darby canine kidney (MDCK) epithelial cell line was chosen as an in vitro experimental model. The results of the viability assay indicated that, compared to control, the number of viable cells attached to the surface of the ZnO urchin and its surrounding area were reduced. The measurements of the Zn contents of cell media confirmed ZnO dissolution, which suggests that the ZnO dissolution in cell culture medium could lead to cytotoxicity. A purposeful reduction of ZnO cytotoxicity was achieved by surface coating of the ZnO urchin with poly(vinylidene fluorid-co-hexafluoropropylene) (PVDF-HFP), which changed the material matrix to slow the Zn ion release and consequently reduce the cytotoxicity of the ZnO urchin without reducing its functionality.
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Affiliation(s)
- Roghayeh Imani
- Laboratory of Biophysics, Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, Ljubljana, SI-1000, Slovenia.
- Laboratory of Clinical Biophysics, Faculty of Health Sciences, University of Ljubljana, Ljubljana, SI-1000, Slovenia.
| | - Barbara Drašler
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, SI-1000, Ljubljana, Slovenia.
| | - Veno Kononenko
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, SI-1000, Ljubljana, Slovenia.
| | - Tea Romih
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, SI-1000, Ljubljana, Slovenia.
| | - Kristina Eleršič
- Department of Surface Engineering and Optoelectronics, Jožef Stefan Institute, Jamova 39, Ljubljana, SI-1000, Slovenia.
| | - Janez Jelenc
- Solid State Physics Department, Jožef Stefan Institute, Jamova 39, SI-1000, Ljubljana, Slovenia.
| | - Ita Junkar
- Department of Surface Engineering and Optoelectronics, Jožef Stefan Institute, Jamova 39, Ljubljana, SI-1000, Slovenia.
| | - Maja Remškar
- Solid State Physics Department, Jožef Stefan Institute, Jamova 39, SI-1000, Ljubljana, Slovenia.
| | - Damjana Drobne
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, SI-1000, Ljubljana, Slovenia.
| | - Veronika Kralj-Iglič
- Laboratory of Clinical Biophysics, Faculty of Health Sciences, University of Ljubljana, Ljubljana, SI-1000, Slovenia.
| | - Aleš Iglič
- Laboratory of Biophysics, Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, Ljubljana, SI-1000, Slovenia.
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Novak S, Drobne D, Vaccari L, Kiskinova M, Ferraris P, Birarda G, Remškar M, Hočevar M. Effect of ingested tungsten oxide (WOx) nanofibers on digestive gland tissue of Porcellio scaber (Isopoda, Crustacea): fourier transform infrared (FTIR) imaging. Environ Sci Technol 2013; 47:11284-11292. [PMID: 23952740 DOI: 10.1021/es402364w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Tungsten nanofibers are recognized as biologically potent. We study deviations in molecular composition between normal and digestive gland tissue of WOx nanofibers (nano-WOx) fed invertebrate Porcellio scaber (Iosopda, Crustacea) and revealed mechanisms of nano-WOx effect in vivo. Fourier Transform Infrared (FTIR) imaging performed on digestive gland epithelium was supplemented by toxicity and cytotoxicity analyses as well as scanning electron microscopy (SEM) of the surface of the epithelium. The difference in the spectra of the Nano-WOx treated and control cells showed up in the central region of the cells and were related to lipid peroxidation, and structural changes of nucleic acids. The conventional toxicity parameters failed to show toxic effects of nano-WOx, whereas the cytotoxicity biomarkers and SEM investigation of digestive gland epithelium indicated sporadic effects of nanofibers. Since toxicological and cytological measurements did not highlight severe effects, the biochemical alterations evidenced by FTIR imaging have been explained as the result of cell protection (acclimation) mechanisms to unfavorable conditions and indication of a nonhomeostatic state, which can lead to toxic effects.
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Affiliation(s)
- Sara Novak
- Department of Biology, Biotechnical Faculty, University of Ljubljana , Ljubljana, Slovenia
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Millaku A, Drobne D, Torkar M, Novak S, Remškar M, Pipan-Tkalec Ž. Use of scanning electron microscopy to monitor nanofibre/cell interaction in digestive epithelial cells. J Hazard Mater 2013; 260:47-52. [PMID: 23742956 DOI: 10.1016/j.jhazmat.2013.04.041] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 04/25/2013] [Accepted: 04/26/2013] [Indexed: 06/02/2023]
Abstract
We provide data obtained by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) on the interaction of ingested tungsten nanofibers with epithelial cells of the digestive tubes of a test organism Porcellio scaber. Conventional toxicity endpoints including feeding behaviour, weight loss and mortality were also measured in each investigated animal. No toxicity was detected in any of exposed animals after 14 days of feeding on tungsten nanofiber dosed food, but when nanofibers enter the digestive system they can react with epithelial cells of the digestive tubes, becoming physically inserted into the cells. In this way, nanofibers can injure the epithelial cells of digestive gland tubes when they are ingested with food. Our SEM data suggest that peristaltic forces may have an important role, not predicted by in vitro experiments, in the interactions of nanomaterials with digestive intestinal cells.
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Affiliation(s)
- Agron Millaku
- Limnos-Company for Applied Ecology Ltd, Podlimbarskega 31, 1000 Ljubljana, Slovenia.
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Likon M, Remškar M, Ducman V, Švegl F. Populus seed fibers as a natural source for production of oil super absorbents. J Environ Manage 2013; 114:158-67. [PMID: 22516250 DOI: 10.1016/j.jenvman.2012.03.047] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 03/16/2012] [Accepted: 03/21/2012] [Indexed: 05/26/2023]
Abstract
The genus Populus, which includes poplars, cottonwoods and aspen trees, represents a huge natural source of fibers with exceptional physical properties. In this study, the oil absorption properties of poplar seed hair fibers obtained from Populus nigra italica when tested with high-density motor oil and diesel fuel are reported. Poplar seed hair fibers are hollow hydrophobic microtubes with an external diameter between 3 and 12 μm, an average length of 4±1 mm and average tube wall thickness of 400±100 nm. The solid skeleton of the hollow fibers consists of lignocellulosic material coated by a hydrophobic waxy coating. The exceptional chemical, physical and microstructural properties of poplar seed hair fibers enable super-absorbent behavior with high absorption capacity for heavy motor oil and diesel fuel. The absorption values of 182-211 g heavy oil/g fiber and 55-60 g heavy oil/g fiber for packing densities of 0.005 g/cm(3) and 0.02 g/cm(3), respectively, surpass all known natural absorbents. Thus, poplar seed hair fibers obtained from Populus nigra italica and other trees of the genus Populus are an extremely promising natural source for the production of oil super absorbents.
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Affiliation(s)
- Marko Likon
- Insol Ltd, Cankarjeva 16 a, SI-6230 Postojna, Slovenia.
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Novak S, Drobne D, Valant J, Pipan-Tkalec Ž, Pelicon P, Vavpetič P, Grlj N, Falnoga I, Mazej D, Remškar M. Cell membrane integrity and internalization of ingested TiO(2) nanoparticles by digestive gland cells of a terrestrial isopod. Environ Toxicol Chem 2012; 31:1083-90. [PMID: 22447647 DOI: 10.1002/etc.1791] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Revised: 09/25/2011] [Accepted: 12/12/2011] [Indexed: 05/23/2023]
Abstract
The present study was motivated by the paucity of reports on cellular internalization of ingested titanium dioxide (TiO(2)) nanoparticles (nano-TiO(2)). The model invertebrate (Porcellio scaber, Isopoda, Crustacea) was exposed to food dosed with nano-TiO(2) containing 100, 1,000, 3,000, or 5,000 µg nano-TiO(2) per gram of food. After 14 d of exposure, the amount of Ti in the entire body was analyzed by inductively coupled plasma-mass spectrometry, and elemental analyses of tissue cross sections were performed by particle induced X-ray emission. In addition, a series of toxicological markers including feeding parameters, weight change, and survival, as well as cytotoxic effects such as digestive gland cell membrane stability, were monitored. Internalization of ingested nano-TiO(2) by the isopod's digestive gland epithelial cells was shown to depend on cell membrane integrity. Cell membranes were found to be destabilized by TiO(2) particles, and at higher extracellular concentrations of nano-TiO(2), the nanoparticles were internalized.
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Affiliation(s)
- Sara Novak
- University of Ljubljana, Biotechnical Faculty, Department of Biology, Ljubljana, Slovenia
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Naffakh M, Díez-Pascual AM, Remškar M, Marco C. New inorganic nanotube polymer nanocomposites: improved thermal, mechanical and tribological properties in isotactic polypropylene incorporating INT-MoS2. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm33422d] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Naffakh M, Remškar M, Marco C, Gómez-Fatou MA. Dynamic Crystallization Kinetics and Nucleation Parameters of a New Generation of Nanocomposites Based on Isotactic Polypropylene and MoS2 Inorganic Nanotubes. J Phys Chem B 2011; 115:2850-6. [DOI: 10.1021/jp1115788] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mohammed Naffakh
- Departamento de Física e Ingeniería de Polímeros, Instituto de Ciencia y Tecnología de Polímeros, CSIC, c/Juan de la Cierva, 3, 28006, Madrid, Spain
| | - Maja Remškar
- Jožef Stefan Institute, Jamona 39, SI-1000 Ljubljana, Slovenia
- Centre of Excellence PoliMat, Tehnoloski Park 24, SI-1000 Ljubljana, Slovenia
| | - Carlos Marco
- Departamento de Física e Ingeniería de Polímeros, Instituto de Ciencia y Tecnología de Polímeros, CSIC, c/Juan de la Cierva, 3, 28006, Madrid, Spain
| | - Marián A. Gómez-Fatou
- Departamento de Física e Ingeniería de Polímeros, Instituto de Ciencia y Tecnología de Polímeros, CSIC, c/Juan de la Cierva, 3, 28006, Madrid, Spain
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Naffakh M, Remškar M, Marco C, Gómez-Fatou MA, Jiménez I. Towards a new generation of polymer nanocomposites based on inorganic nanotubes. ACTA ACUST UNITED AC 2011. [DOI: 10.1039/c0jm04471g] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Chambers M, Finkelmann H, Remškar M, Sánchez-Ferrer A, Zalar B, Žumer S. Liquid crystal elastomer–nanoparticle systems for actuation. ACTA ACUST UNITED AC 2009. [DOI: 10.1039/b812423j] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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30
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Milošev I, Remškar M. In vivoproduction of nanosized metal wear debris formed by tribochemical reaction as confirmed by high-resolution TEM and XPS analyses. J Biomed Mater Res A 2008; 91:1100-10. [DOI: 10.1002/jbm.a.32301] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Chambers M, Zalar B, Remškar M, Finkelmann H, Zumer S. Piezoresistivity and electro-thermomechanical degradation of a conducting layer of nanoparticles integrated at the liquid crystal elastomer surface. Nanotechnology 2008; 19:155501. [PMID: 21825613 DOI: 10.1088/0957-4484/19/15/155501] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
When a liquid crystal elastomer (LCE) is reprocessed with conducting nanosized particles a conducting layer can be formed at the LCE surfaces. Here, two different LCE materials and two different conducting carbon particles were used. These four reprocessed LCEs were investigated when subject to a thermal phase transition and mechanical extension. Here it is shown that the resistance change with strain ('piezoresistivity') for these reprocessed LCEs can be described through lattice percolation and geometrical changes in the LCE shape. The mechanisms and rate of degradation are also described for the conducting layer as a function of the number of electro-thermomechanical strain cycles performed.
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Dominko R, Bele M, Gaberšček M, Meden A, Remškar M, Jamnik J. Structure and electrochemical performance of Li2MnSiO4 and Li2FeSiO4 as potential Li-battery cathode materials. Electrochem commun 2006. [DOI: 10.1016/j.elecom.2005.11.010] [Citation(s) in RCA: 348] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Godec M, Remškar M, Mandrino D, Šuštaršič B, Jenko M. The development of a Fe74Si11B14Ni1 soft magnetic powder used for SMC materials. SURF INTERFACE ANAL 2004. [DOI: 10.1002/sia.1799] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Jagličić Z, Jeromen A, Trontelj Z, Mihailović D, Arčon D, Remškar M, Mrzel A, Dominko R, Gaberšček M, Martinez-Agudo JM, Gómez-Garcia CJ, Coronado E. Magnetic properties of MoS 2 nanotubes doped with lithium. Polyhedron 2003. [DOI: 10.1016/s0277-5387(03)00181-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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35
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Tonti D, Varsano F, Decker F, Ballif C, Regula M, Remškar M. Preparation and Photoelectrochemistry of Semiconducting WS2 Thin Films. J Phys Chem B 1997. [DOI: 10.1021/jp962550i] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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