| 1. |
- Bilgic, Mehmet B., et al.
(författare)
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An unusual zig-zag 2D copper(i) coordination polymer as an outstanding catalyst for azide–alkyne “click” chemistry at room temperature
- 2022
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 51:46, s. 17543-17546
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Tidskriftsartikel (refereegranskat)abstract
- A straightforward method for the synthesis of a two-dimensional (2D) new copper(I) coordination polymer, namely Cu(bzpdc), containing the ligand benzophenone 4,4′-dicarboxylate, and its effective use as catalyst for the azide–alkyne click chemistry at room temperature is reported. Zig-zag formation caused by cuprophilic interactions resulted in an unprecedented crystal structure with a very high copper content (45.5% by weight). The catalyst was stable up until 300 °C and tolerant to various solvents, including water. Cu(bzpdc) showed excellent catalytic activity for click reactions of several organic azides and alkynes having different functional groups at room temperature and is comparable to its homogenous analogues. The recyclability of Cu(bzpdc) was also tested and proven to be effective.
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| 2. |
- Iseri, Emre, et al.
(författare)
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Slip-X-Chip: A sliding microfluidic platform with cross-flow
- 2022
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Ingår i: 2022 IEEE 35th International Conference on Micro Electro Mechanical Systems Conference (MEMS). - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 912-914
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Konferensbidrag (refereegranskat)abstract
- In sliding microfluidic platforms (“SlipChip” [1]), two plates with microfluidic wells slide in close contact to perform multiplexed reactions in a single operation. In- plane “sliding-flow” liquid transport, however, limits the potential assay operations to 1) sample compartmentalization/metering, 2) reagent addition, 3) mixing, and 4) aliquoting. Here, we introduce a three-plate sliding microfluidics platform, “Slip-X-Chip”, that additionally includes out-of-plane “cross-flow” liquid transport. Slip-X-Chip allows two additional assay operations: 5) sample concentration and 6) liquid exchange/washing, while retaining the simplicity of operation (one-step operation; no precise pipetting required; no external equipment). These additional assay operations extend the range and complexity of applications enabled by sliding microfluidics. We here demonstrate 1) splitting bead solutions in compartments with different concentrations and 2) compartmentalizing human cells from solution, followed by a viability assay. We foresee that Slip-X-Chip could be further adapted to, e.g., cell counting, cell staining, or ELISA.
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| 3. |
- Iseri, Emre, et al.
(författare)
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Tuneable Microparticle Filters
- 2019
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Ingår i: 2019 IEEE 32nd International Conference on Micro Electro Mechanical Systems (MEMS). - : IEEE. ; , s. 290-291
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Konferensbidrag (refereegranskat)abstract
- We introduce microparticle filters with temperature tuneable size cut-off and surface energy. At room temperature, the filter cut-off is 164 ±23 μm, and the filter is water-absorbing/oil-repelling (hydrophilic). At 50 °C, the filter cut-off is 695±31 μm, and the filter is oil-absorbing/water-repelling (hydrophobic).
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| 4. |
- Kaya, Kerem, et al.
(författare)
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Enhanced Solar CO2 Photoreduction to Formic Acid by Platinum Immobilization on Bipyridine Covalent Triazine Framework with Defects
- 2023
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Ingår i: Advanced Sustainable Systems. - 2366-7486. ; 7:8
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Tidskriftsartikel (refereegranskat)abstract
- The immobilization and structural analysis of platinum nanoparticles on a nitrogen-rich, bipyridine-containing covalent triazine framework (bpyCTF) having structural defects are disclosed by taking advantage of 15N solid-state nuclear magnetic resonance measurements at natural 15N isotope abundance and X-ray photoelectron spectroscopic analyses. The photocatalyst (Pt@bpyCTF) with structural defects reduces CO2 to formic acid (FA) at a rate of 152 µmol h−1g−1 and a selectivity higher than 95% over CO and H2 in water under simulated solar light. The presence of amine defects and the immobilization of Pt cause improvement in the photocurrent density and CO2 capture capacity (≈8% by weight) despite the moderate surface area (0.54 cm3 g−1)of the photocatalyst. Theoretical models and density functional theory calculations are employed to investigate the possible CO2 reduction reaction (CO2RR) mechanisms. Considering the exceptional CO2 capture capacity and high FA production using only CO2-bubbled water, this work highlights the great potential of nitrogen-rich CTFs for photocatalyzed CO2RRs under green conditions.
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| 5. |
- Kaya, Kerem, et al.
(författare)
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Nature-Inspired Depolymerization of Soda Lignin : Light-Induced Free Radical Promoted Cleavage of β-O-4 Bonds
- 2024
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Ingår i: Advanced Sustainable Systems. - 2366-7486. ; 8:3
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Tidskriftsartikel (refereegranskat)abstract
- The development of sustainable valorization methods for lignin is a challenging task because the vast majority of the reported studies involve either harsh conditions or expensive transition metal catalysts. Inspired by the sunlight degradation of lignin compounds, known as lignin yellowing, the use of a commercially available cheap organic photoinitiator, namely, phenacyl bromide (PAB) is reported here, for the efficient cleavage of lignin model compound 2-phenoxyacetophenone (2-PAP) and for the depolymerization of soda pulped lignin (SL) under UV-A irradiation and ambient conditions. Real-time NMR investigations of the photoreaction between 2-PAP and PAB shed light on the possible reaction mechanisms involving different radical species, HBr, and molecular oxygen. Interestingly, combined spectral, chromatographic, powder X-ray diffraction, and thermal studies of the photoreaction between PAB and SL indicate the formation of guaiacyl alcohol as the main product. The unprecedented performance of PAB is attributed to the excess generation of phenacyl radicals, the generation of photolabile brominated species, and HBr playing key roles in the cleavage of β-O-4 linkages. This work represents a new edge for sustainable lignin valorization under mild reaction conditions and offers the opportunity for large-scale production of valuable aromatics using technical lignins as feedstock.
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| 6. |
- Kaya, Kerem, et al.
(författare)
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Programmable Matter with Free and High-Resolution Transfiguration and Locomotion
- 2024
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Ingår i: Advanced Functional Materials. - : Wiley. - 1616-301X .- 1616-3028. ; 34:14
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Tidskriftsartikel (refereegranskat)abstract
- “Hot flow in the coldchanges shape in a dead worldcomes matter to life”Programmable matter that allows free shape transfiguration and locomotionon command promises ubiquitous access to objects or functions of interest.Current approaches for the autonomous reshaping of solid objects (smartmaterials, soft actuators, modular robotics) are limited in spatial resolution andshape. Solid-liquid phase change pumping as a mechanism for the contactlesstransfiguring and locomotion of solid objects is introduced. Thin objects aredeformed into any intended shape with sub-millimeter resolution and the abilityto freely change their topology is demonstrated, including adding or removingholes, splitting and merging. The unique locomotion of objects throughmillimeter-sized constrictions narrower than their body size is demonstrated,followed by restoring the original shape. This approach opens up avenues fordeveloping autonomous programmable matter with free shape transfiguration.
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| 7. |
- Kaya, Kerem, et al.
(författare)
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Programmable Switched-Capacitor Filter Design Tool for Biomedical Signal Acquisition
- 2023
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Ingår i: Proceedings. - : Institute of Electrical and Electronics Engineers (IEEE).
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Konferensbidrag (refereegranskat)abstract
- This paper presents an open source design support tool for a respiratory and cardiac signal acquisition system that utilizes programmable switched-capacitor analog filters in the analog front end. The proposed filter topologies are based on cascaded second-order-section filters and are designed to be programmable in terms of the cut-off frequency via the switching frequency. The design support tool is written in Python and is capable of calculating the capacitance ratios for a given second-order filter topology, generating a parameter file, and performing periodic AC simulations of the designed circuit in SpectreRF. The tool uses a simple estimation algorithm to find the best possible integer fit with an error cost function. Two sets of 6th-order switched-capacitor filter sets are designed using biquadratic sections in 180nm CMOS process. The proposed design methodology offers a better area fraction reduction compared to simple integer ratio designs. Post-layout simulation results demonstrate the effectiveness and efficiency of the proposed design support tool for switched-capacitor analog filters in respiratory and cardiac signal acquisition systems.
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| 8. |
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| 9. |
- Kaya, Kerem, et al.
(författare)
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Soft metamaterial with programmable ferromagnetism
- 2022
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Ingår i: Microsystems & Nanoengineering. - : Springer Nature. - 2055-7434. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Magnetopolymers are of interest in smart material applications; however, changing their magnetic properties post synthesis is complicated. In this study, we introduce easily programmable polymer magnetic composites comprising 2D lattices of droplets of solid-liquid phase change material, with each droplet containing a single magnetic dipole particle. These composites are ferromagnetic with a Curie temperature defined by the rotational freedom of the particles above the droplet melting point. We demonstrate magnetopolymers combining high remanence characteristics with Curie temperatures below the composite degradation temperature. We easily reprogram the material between four states: (1) a superparamagnetic state above the melting point which, in the absence of an external magnetic field, spontaneously collapses to; (2) an artificial spin ice state, which after cooling forms either; (3) a spin glass state with low bulk remanence, or; (4) a ferromagnetic state with high bulk remanence when cooled in the presence of an external magnetic field. We observe the spontaneous emergence of 2D magnetic vortices in the spin ice and elucidate the correlation of these vortex structures with the external bulk remanence. We also demonstrate the easy programming of magnetically latching structures.
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| 10. |
- Krivánková, Nikola, et al.
(författare)
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Copper-mediated synthesis of temperature-responsive poly(N-acryloyl glycinamide) polymers : a step towards greener and simple polymerisation
- 2023
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 13:42, s. 29099-29108
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Tidskriftsartikel (refereegranskat)abstract
- Stimuli-responsive materials with reversible supramolecular networks controlled by a change in temperature are of interest in medicine, biomedicine and analytical chemistry. For these materials to become more impactful, the development of greener synthetic practices with more sustainable solvents, lower energy consumption and a reduction in metallic catalysts is needed. In this work, we investigate the polymerisation of N-acryloyl glycinamide monomer by single-electron transfer reversible-deactivation radical polymerisation and its effect on the cloud point of the resulting PNAGA polymers. We accomplished 80% conversion within 5 min in water media using a copper wire catalyst. The material exhibited a sharp upper critical solution temperature (UCST) phase transition (10–80% transition within 6 K). These results indicate that UCST-exhibiting PNAGA can be synthesized at ambient temperatures and under non-inert conditions, eliminating the cost- and energy-consuming deoxygenation step. The choice of copper wire as the catalyst allows the possibility of catalyst recycling. Furthermore, we show that the reaction is feasible in a simple vial which would facilitate upscaling.
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