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Structural, physicochemical and anticancer study of Zn complexes with pyridyl-based thiazolyl-hydrazones
- Jovana B. Araškov
- Natalia Maciejewska
- Mateusz Olszewski
- Aleksandar Višnjevac
- Vladimir Blagojević
- Henrique S. Fernandes
- Sérgio F. Sousa
- Adrián Puerta
- José M. Padrón
- Berta Barta Holló
- Miguel Monge
- María Rodríguez-castillo
- José M. López-de-luzuriaga
- Özlem Uğuz
- Atıf Koca
- Tamara R. Todorović
- Nenad R. Filipovići
2023 JOURNAL OF MOLECULAR STRUCTURE
Thiazolyl-hydrazones (THs) exhibit a wide spectrum of biological activity that can be enhanced by complexation with various metal ions. Zn(II) complexes with α-pyridine-1,3-TH ligands may represent an alternative to the standard platinum-based chemotherapeutics. In addition, they show photoluminescence properties and thus can be regarded as multifunctional materials. In this study, we synthesized and characterized three neutral Zn(II) complexes (1–3) with pyridine-based TH ligands HLS1‒3 in order to investigate the influence of the ligands charge on the structure and intermolecular interactions in the solid state, and consequently photophysical properties. The deprotonation of the ligands mainly affects the relative energies of electronic levels in the complexes, compared to cationic counterparts, resulting in similar photoluminescence mechanisms and quantum yields with a small shift in emission energy. The influence of the substitution at the ligands’ periphery on the selected quantum molecular descriptors of the complexes is localized to the substitution site. Also, the substituents did not considerably influence the redox responses of the complexes. However, predominant spectral changes were observed in the course of the first reduction and oxidation processes which caused distinct spectral colour changes indicating their possible functionality for electrochromic applications. In addition, complex 1 showed antiproliferative activity with GI50 values below 2 µM on all tested cancer cell lines.
Structurally well-defined functionalized polyolefins and graft copolymers thereof as bitumen modifiers
- Mateusz Malus
- Joanna Bojda
- Maciej Sienkiewicz
- Miloud Bouyahyi
- Lanti Yang
- Javier Francisco Navarro
- Maria Soliman
- Rob Duchateau
- Lidia Jasińska-Walc
2023 CONSTRUCTION AND BUILDING MATERIALS
Here we demonstrate the application of hydroxyl-functionalized propylene-based copolymers, poly(propylene-co-1-hexene-co-10-undecen-1-ol) (FPP) and poly(styrene-co-maleic anhydride) (SMA) graft copolymers derived thereof, poly(propylene-co-1- hexene-graft-styrene-co-maleic anhydride) (FPP-g-SMA) as bitumen modifiers. The FPP samples were synthesized via solution copolymerization, while FPP-g-SMA products were obtained via transesterification of FPP with SMA either in solution or by a melt-grafting process. FPP-g-SMA modifiers prepared in solution, having a SMA content of around 30 wt.%, performed very well as compatibilizer for bitumen, generating a polymer-modified compositions with a uniform morphology and improved nanomechanical properties, storage stability, rheological properties and high- temperature performance as compared to neat bitumen samples.
Structure redetermination, transport and thermal properties of the YNi3Al9 compound
- Ihor Oshchapovskyy
- Ebube E. Oyeka
- Thao Tran
- Tomasz Klimczuk
- Michał Winiarski
2023 Pełny tekst JOURNAL OF SOLID STATE CHEMISTRY
Single crystals of completely ordered variant of the YNi3Al9 compound were grown by self-flux method with excess of aluminum. The crystal structure of the title compound was redetermined from single crystal X-ray diffraction data. The structure adopts ErNi3Al9 type, space group R32, parameters of the unit cell a = 7.2838(2) Å, c = 27.4004(8) Å. The growth of relatively large single crystals of the YNi3Al9 compound, having completely ordered structure, indicates possible existence of region on phase diagram, where the title compound is in equilibrium with liquid. Comparison with the results in the literature on the investigations of the same and related compounds shows trend towards formation of more ordered structures in flux grown samples and more disordered ones in arc melted samples. Physical properties of the title compound - electrical resistivity, magnetoresistance and heat capacity - were measured for the first time. It shows metallic-like behavior with very high values of magnetoresistance up to 420% at low temperatures without presence of magnetic elements. Therefore electronic structure calculations were carried out. The phonon heat capacity reveals major Debye and minor Einstein contributions at the intermediate temperatures, and total heat capacity approaches Dulong-Petit limit at high temperatures. The calculated Debye temperature from the whole temperature range θD = 480(6) K is typical for aluminium-rich compounds. Corresponding Einstein temperature is θE = 198(8) K. The estimations of electron-phonon coupling constant λ = 0.092 show very weak coupling and absence of superconducting transition.
Structured deformation of granular material in the state of active earth pressure
- Leśniewska Danuta
- A. Tordesillas
- Magdale Pietrzak
- Shuo Zhou
- Michał Nitka
2023 Pełny tekst COMPUTERS AND GEOTECHNICS
The paper focuses on the ability of granular materials to undergo structured deformation by analysing the data from the retaining wall model tests and discrete element simulations. The structured deformation means the movement of a granular material which produces a stable, regular pattern of multiple shear bands. The paper's primary purpose is to study this kind of deformation for the selected data representing the state of active earth pressure of granular materials. The locations of high and negligible shear strains (shear zones and 'dead' zones) in the displacement fields are determined using the shear strains definition. A recently introduced metric called s-LID, expressing the perspective of collective grain motion, is applied to the same data. The s-LID analysis finds the detailed structure of the localisation pattern directly from displacement data without using the continuum mechanics concept of strains. It is entirely consistent with the digital image correlation analysis in the areas of significant displacement. It expands the knowledge of the deformation structure in small displacement areas, where the digital image correlation method loses its capability. Low s-LID and point-like representations in the displacement state space identify nearly rigid zones in the area of high displacements.
Structure-Property Relationship and Multiple Processing Studies of Novel Bio-Based Thermoplastic Polyurethane Elastomers
- Joanna Smorawska
- Marcin Włoch
- Ewa Głowińska
2023 Pełny tekst Materials
Currently, the growing demand for polymeric materials has led to an increased need to develop effective recycling methods. This study focuses on the multiple processing of bio-based thermoplastic polyurethane elastomers (bio-TPUs) as a sustainable approach for polymeric waste management through mechanical recycling. The main objective is to investigate the influence of two reprocessing cycles on selected properties of bio-TPUs. Two series of bio-based TPUs were synthesized via a solvent-free two-step method with the use of hexamethylene diisocyanate or hexamethylene diisocyanate/partially bio-based diisocyanate mixtures, bio-based poly(triamethylene ether) glycol, and bio-based 1,3 propanediol. Both the raw bio-TPUs and those subjected to two reprocessing cycles were examined with respect to their chemical, physical, thermal, thermomechanical, and mechanical properties. The conducted research revealed that reprocessing led to changes in the phase separation between the hard and soft segments, thereby affecting the bio-TPUs’ properties. Both series of materials showed similar chemical structures regardless of reprocessing (slight changes were observed in the range of carbonyl peak). The thermal properties of TPUs exhibited slight differences after each reprocessing cycle, but generally, the non-processed and reprocessed bio-TPUs were thermally stable up to about 300 °C. However, significant differences were observed in their mechanical properties. The tensile strength increased to 34% for the twice-reprocessed bio-TPUs, while the elongation at break increased by ca. 200%. On the other hand, the processing cycles resulted in a decrease in the hardness of both bio-TPU series (ca. 3–4 °ShA). As a result, the prepared bio-TPUs exhibited characteristics that were closer to those of the sustainable materials model, promoting the circular economy of plastics, with environmental benefits arising from their recyclability and their high content of bio-based monomers (78.4–78.8 wt.%).
Study of Soil Temperature and Moisture Changes in a Physical Model of an Underground Cable Line
- Stanisław Czapp
- Filip Ratkowski
- Seweryn Szultka
- Krzysztof Szuchnik
- Michał Kołtun
2023
The ampacity of power cables is highly dependent on the thermal resistivity of the soil in which they are laid. The lower it is, the higher this ampacity. The thermal resistivity of the soil decreases as its moisture increases. Therefore, it is preferable that the soil around the cables has high moisture. Unfortunately, the heat generated in heavily loaded cables causes the migration of moisture from the surrounding soil, which adversely affects the ampacity of these cables. However, it turns out that it is possible to stop the migration of moisture from the immediate vicinity of the cables. The paper presents the results of a long-term experiment (soil/betonite temperature and moisture measurements), which proves that proper protection of the medium around the cables makes it possible to stop the migration of moisture. This has a positive effect on the ampacity of the cables and, thus, on the level of transmitted power.
Study of various machine learning approaches for Sentinel-2 derived bathymetry
- Andrzej Chybicki
- Paweł Sosnowski
- Marek Kulawiak
- Tomasz Bieliński
- Waldemar Korlub
- Zbigniew Łubniewski
- Magdalena Kempa
- Jarosław Parzuchowski
2023 Pełny tekst PLOS ONE
In recent years precise and up-to-date information regarding seabed depth has become more and more important for companies and institutions that operate on coastlines. While direct, in-situ measurements are performed regularly, they are expensive, time-consuming and impractical to be performed in short time intervals. At the same time, an ever-increasing amount of satellite imaging data becomes available. With these images, it became possible to develop bathymetry estimation algorithms that can predict seabed depth and utilize them systematically. Since there are a number of theoretical approaches, physical models, and empirical techniques to use satellite observations in order to estimate depth in the coastal zone, the presented article compares the performance and precision of the most common one to modern machine learning algorithms. More specifically, the models based on shallow neural networks, decision trees and Random Forest algorithms have been proposed, investigated and confronted with the performance of pure analytical models. The particular proposed machine learning models differ also in a set of satellite data bands used as an input as well as in applying or not geographical weighting in the learning process. The obtained results point towards the best performance of the regression tree algorithm that incorporated as inputs information about data localization, raw reflectance data from four satellite data bands and a quotient of logarithms of B2 and B3 bands. The study for the paper was performed in relatively optically difficult and spatially variant conditions of the south Baltic coastline starting at Szczecin, Poland on the west (53˚26’17’’ N, 14˚32’32’’ E) to Hel peninsula (54˚43’04,3774’’ N 18˚37’56,9175’’ E). The reference bathymetry data was acquired from Polish Marine Administration. It was obtained through profile probing with single-beam sonar or direct in-situ probing.
Study of ZrS3-based field-effect transistors toward the understanding of the mechanisms of light-enhanced gas sensing by transition metal trichalcogenides
- Katarzyna Drozdowska
- Adil Rehman
- Sergey Rumyantsev
- Michelle Wurch
- Ludwig Bartels
- Alexander Balandin
- Janusz Smulko
- Grzegorz Cywiński
2023 Pełny tekst Materials Today Communications
Extending knowledge of the properties of low-dimensional van der Waals materials, including their reactivity to the ambiance, is important for developing innovative electronic and optoelectronic devices. Transition metal trichalcogenides with tunable optical band gaps and anisotropic conductivity are an emerging class among low- dimensional structures with the possibility of gate tunability and photoreactivity. These properties can be combined into light-enhanced field-effect transistor gas sensors. We demonstrated prototype zirconium trisulfide (ZrS3) sensors for nitrogen dioxide, ethanol, and acetone. Photoconductivity and photogating play a critical role in photoinduced gas sensing, with the dominance of the first for blue (470 nm) and green (515 nm) and the second one prevailing for red (700 nm) irradiations. Our results suggest that surface trap states lead both to trapping and scattering of the charge carriers in the channel. The gas detection is guided by charge transfer and modulation of the carrier mobility, resulting in distinct I-V characteristics for selected irradiation conditions.
Study on effective front region thickness of PCM in thermal energy storage using a novel semi-theoretical model
- Rafał Andrzejczyk
- Muhammad Saqib
- Tomasz Kowalczyk
- Hafiz Muhammad Ali
2023 Pełny tekst INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
Thermal energy storage in mobile applications, particularly battery of electric vehicles, is currently gaining a lot of importance. In this paper, a semi-theoretical time-dependent mathematical model of the phase change in a double shell thermal energy storage module has been developed where the inner tube is a heat exchange surface. An effective front region thickness for the melting and solidification process has been studied. The proposed model is calibrated based on our experimental data. The purpose of such a model is to enable the optimization of the geometry of the energy storage modules in terms of the PCM to the TES container mass ratio and enhancement of phase change rate. In addition, results obtained for a single tube can be used in the bundle of tubes in shell and tube TES design. The results have shown that for the larger diameter of the module (smaller difference between the working tube and shell diameter) the optimal working time is around 2000 s.
Study on Microstructure-Property Relationship of Inconel 617 Alloy/304L SS Steel Dissimilar Welds Joint
- Amit Kumar
- Krishna Guguloth
- Shailesh M. Pandey
- Dariusz Fydrych
- Sachin Sirohi
- Chandan Pandey
2023 METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
Welding of Inconel 617 (IN617) alloy and austenitic 304L SS steel has been attempted using the autogenous Laser Beam Welding (LBW) process. Characterization of dissimilar weldments was performed on either side of the fusion boundaries. The metallographic results showed that the inhomogeneous microstructure formation for weld metal contained columnar and cellular dendrites near the interface, whilst the columnar, cellular and equiaxed types of dendrites were in the weld centre. The energy dispersive spectroscopy (EDS) and electron probe microanalysis (EPMA) studies revealed the white layer near the interface on both sides of the fusion line, as well as a significant change in the concentration of alloying elements (Fe, Cr, Ni, Co, and Mo). The weld metal accompanied by Cr, Ti and Mo precipitates evolved in the inter-dendritic spaces. The Cr and Mo-rich M23C6 and Mo-rich M6C phases in IN617 heat-affected zone (HAZ) were found in SEM/EDS and EPMA studies. The 304L SS side showed a distinct HAZ, whilst on the IN617 side, no distinct HAZ was seen. Samples were prepared from the dissimilar weldments to evaluate their mechanical properties, such as tensile strength and hardness. The microhardness plot showed the non-uniformity in hardness along the weldments. The weld metal hardness was 253 ± 10 HV. The tensile test of the welded joint results was compared with the base metals. The tested results exhibited that the failure of the specimen from 304L SS base metal (BM) or from weld metal with tensile strength was marginally lower than the Inconel 617 base metal but significantly higher than the 304L SS BM. The fracture surface study revealed the presence of Mo and Cr segregation in inter-dendritic spaces, which impoverished the tensile properties. The order of impact toughness was measured as follows: 304L SS BM > 304L SS HAZ>IN617 BM>weld metal>IN617 HAZ. The IN617 HAZ was recognised as the weakest area of the weldments in terms of impact strength. The welded joint was considered safe for AUSC application because the stress-rupture properties were evaluated in between base metals data.
Study on transmission quality in cellular 4G and 5G networks between 2019–2021: Impact of the COVID-19 pandemic on the level of provided services by operating base transceiver stations
- Przemysław Falkowski-Gilski
- Tadeus Uhl
2023 Pełny tekst Zeszyty Naukowe Akademii Morskiej w Szczecinie
The COVID-19 pandemic has significantly limited user mobility, not least among students. Remote learning had a particular impact on resource allocation in relation to using terrestrial cellular networks, especially 4G systems in urban agglomerations. This paper presents the results of a quality evaluation of an outdoor environment, carried out between 2019 and 2021 on the campus of a technical university. Annual studies are conducted using our own custom-built mobile application, installed on 50 mobile devices (i.e., smartphones) running Android OS. This study aims to determine the impact of reduced user mobility on access parameters in mobile networks, that is, both download and upload throughput as well as delay (ping), with a particular focus on serving base transceiver stations (BTSs). This research scenario involves long-term evolution (LTE) compatible user equipment (UE) that operates under four Polish mobile network operators (MNO), which includes roaming connections and the newly launched 5G standard.
Substancje groźne, niebezpieczne i pożyteczne. Tom 2. Związki organiczne
- Aleksander Kołodziejczyk
- Aleksandra Kołodziejczyk
2023
Streszczenie W drugim tomie prezentowanej książki przedstawione zostały informacje nt. związków organicznych, ich występowania, otrzymywania, właściwości oraz zagrożeń jakie one stwarzają, a także korzyści, jakich dostarczają. Do związków organicznych zaliczane są te substancje, które zawierają atom lub atomy węgla, z pewnymi wyjątkami (szczegóły w książce). Szacunkowo, liczba znanych związków organicznych sięga kilkudziesięciu milionów (wg PubChem), a rocznie przybywa ich około 200 tys. W związkach organicznych obok węgla i wodoru najczęściej występują także tlen, azot i siarka, dlatego te pięć pierwiastków nazwano pierwiastkami organicznymi. Połączenia organiczne, które zawierają jeszcze inne atomy bezpośrednio związane z atomami węgla noszą nazwy wynikające z ich obecności np. związki z atomami metali nazywane są związkami metaloorganicznymi. Do najczęściej spotykanych należą też związki halogenoorganiczne, siarkoorganiczne czy fosforoorganiczne. Od ich nazw zatytułowane zostały poszczególne rozdziały książki. Z racji bardzo zróżnicowanych edukacyjnie potencjalnych czytelników książki poprzedzono je omówieniem głównych grup związków organicznych, a więc węglowodorów, alkoholi, eterów, związków karbonylowych, kwasów karboksylowych i ich pochodnych. Szczególny nacisk został położony na zagrożenia, jakie stwarzają najniebezpieczniejsze z nich, a także sposoby ochrony przed nimi. Przed przystąpieniem do pisania tej książki z niektórych zagrożeń nie zdawali sobie sprawy nawet jej autorzy, chemicy organicy z długoletnim doświadczeniem. Przykładem może być eteromania, nałóg narkotyzowania się eterem dietylowym, bardzo rozpowszechniony w okresie międzywojennym. Znamiennym przykładem ogromnego zagrożenia jest siarczan dimetylu, popularny odczynnik używany w laboratoriach chemicznych i biochemicznych. Powszechnie wiadomo, że jest to substancja szkodliwa, ale mało kto wie jak bardzo – był rozważany jako potencjalny gaz bojowy.
Succinite, Baltic Amber: A Chemical Masterpiece of Nature
- Ewa Wagner-Wysiecka
2023 Pełny tekst Journal of Gems & Gemmology
Succinite, Baltic amber, is one of the most appreciated fossil resins. Its beauty has fascinated people since prehistoric times. It is a substance, and also gemstone, whose uniqueness is due to its compelling, though still not fully understood, physicochemical nature. In this article, some facts about the physical and chemical properties of succinite in order to find an answer for questions about the unique properties of this resin, such as color, transparency, texture etc., are discussed. These properties are among the factors that determine the choice of Baltic amber as a gemstone. Commonly known properties of succinite, but also some less obvious features, have been linked to the organic and inorganic chemical composition and structural factors, including the sophisticated supramolecular structure masterfully created by nature. Changes of the properties of succinite used as a jewelry stone are discussed as a reflection of changes in its physicochemical nature. In this light, some methods that can be used to identify succinite (i.e., infrared spectroscopy and nuclear magnetic resonance spectroscopy) and their relevance to the classification of fossil resins are briefly discussed. This article highlights an important point: only by understanding the chemical and physical nature of the material we able to identify, modify and effectively use the goods that have been given to us by mother nature.
Suitableness of SLM Manufactured Turbine Blade for Aerodynamical Tests
- Janusz Telega
- Piotr Kaczynski
- Małgorzata Śmiałek-Telega
- Piotr Pawłowski
- Ryszard Szwaba
2023 Pełny tekst Materials
settingsOrder Article Reprints Open AccessArticle Suitableness of SLM Manufactured Turbine Blade for Aerodynamical Tests by Janusz Telega 1,*ORCID,Piotr Kaczynski 1ORCID,Małgorzata A. Śmiałek 2ORCID,Piotr Pawlowski 3ORCID andRyszard Szwaba 1ORCID 1 Institute of Fluid Flow Machinery Polish Academy of Sciences (IMP PAN), Fiszera 14, 80-231 Gdansk, Poland 2 Faculty of Mechanical Engineering and Ship Technology, Institute of Naval Architecture and Ocean Engineering, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk, Poland 3 Institute of Fundamental Technological Research Polish Academy of Sciences (IPPT PAN), Pawinskiego 5B, 02-106 Warsaw, Poland * Author to whom correspondence should be addressed. Materials 2023, 16(7), 2866; https://doi.org/10.3390/ma16072866 Received: 27 February 2023 / Revised: 24 March 2023 / Accepted: 29 March 2023 / Published: 4 April 2023 (This article belongs to the Topic Additive Manufacturing: Design, Opportunities, and Applications) Download Browse Figures Versions Notes Abstract This paper describes some insights on applicability of a Selective Laser Melting and Direct Metal Laser Sintering technology-manufactured turbine blade models for aerodynamic tests in a wind tunnel. The principal idea behind this research was to assess the possibilities of using ‘raw’ DLMS printed turbine blade models for gas-flow experiments. The actual blade, manufactured using the DLMS technology, is assessed in terms of surface quality (roughness), geometrical shape and size (outline), quality of counterbores and quality of small diameter holes. The results are evaluated for the experimental aerodynamics standpoint. This field of application imposes requirements that have not yet been described in the literature. The experimental outcomes prove the surface quality does not suffice to conduct quantitative experiments. The holes that are necessary for pressure measurements in wind tunnel experiments cannot be reduced below 1 mm in diameter. The dimensional discrepancies are on the level beyond acceptable. Additionally, the problem of ‘reversed tolerance’, with the material building up and distorting the design, is visible in elements printed with the DLMS technology. The results indicate the necessity of post-machining of the printed elements prior their experimental usage, as their features in the ‘as fabricated’ state significantly disturb the flow conditions.
Superconductivity in a breathing kagome metals ROs2 (R = Sc, Y, Lu)
- Karolina Górnicka
- Michał Winiarski
- Dorota I. Walicka
- Tomasz Klimczuk
2023 Pełny tekst Scientific Reports
We have successfully synthesized three osmium-based hexagonal Laves compounds ROs2 (R = Sc, Y, Lu), and discussed their physical properties. LeBail refinement of pXRD data confirms that all compounds crystallize in the hexagonal centrosymmetric MgZn2- type structure (P63/mmc, No. 194). The refined lattice parameters are a = b = 5.1791(1) Å and c = 8.4841(2) Å for ScOs2, a = b = 5.2571(3) Å and c = 8.6613(2) Å for LuOs2 and a = b = 5.3067(6) Å and c = 8.7904(1) Å for YOs2. ROs2 Laves phases can be viewed as a stacking of kagome nets interleaved with triangular layers. Temperature-dependent magnetic susceptibility, resistivity and heat capacity measurements confirm bulk superconductivity at critical temperatures, Tc, of 5.36, 4.55, and 3.47 K for ScOs2, YOs2, and LuOs2, respectively. We have shown that all investigated Laves compounds are weakly-coupled type-II superconductors. DFT calculations revealed that the band structure of ROs2 is intricate due to multiple interacting d orbitals of Os and R. Nonetheless, the kagome-derived bands maintain their overall shape, and the Fermi level crosses a number of bands that originate from the kagome flat bands, broadened by interlayer interaction. As a result, ROs2 can be classified as (breathing) kagome metal superconductors
Superconductivity in Bismuth Pyrochlore Lattice Compounds RbBi2 and CsBi2: The Role of Relativistic Effects
- Sylwia Gutowska
- Bartlomiej Wiendlocha
- Tomasz Klimczuk
- Michał Winiarski
2023 Pełny tekst Journal of Physical Chemistry C
Superconducting properties of two bismuthide intermetallic compounds, RbBi2 and CsBi2, were studied by means of experimental measurements and ab initio calculations. We show that in both compounds, the superconductivity emerges from the pyrochlore Bi lattice and its formation is heavily influenced by relativistic effects. Based on our analysis of the effect of spin–orbit coupling on the electron–phonon coupling, we suggest a possible criterion for finding new superconducting materials by looking for structures featuring relativistically stabilized hypervalent networks of heavy p-block elements.
Superconductivity of Ta-Hf and Ta-Zr alloys: Potential alloys for use in superconducting devices
- Tomasz Klimczuk
- Szymon Królak
- Robert J. Cava
2023 Pełny tekst Physical Review Materials
The electronic properties relevant to superconductivity are reported for bulk Ta-Hf and Ta-Zr body centered cubic alloys, in a large part to determine whether their properties are suitable for potential use in superconducting qbits. The body centered cubic unit cell sizes increase with increasing alloying. The results of magnetic susceptibility, electrical resistivity, and heat capacity characterization are reported. While elemental Ta is a type I superconductor, the alloys are type II strong coupling superconductors. Although decreasing the electron count per atom is expected to increase the density of electronic states at the Fermi level and thus the superconducting transition temperature (Tc) in these systems, we find that this is not sufficient to explain the significant increases in the superconducting Tc’s observed.
Superhydrophobic and superoleophilic melamine sponges impregnated with deep eutectic solvents for oil spill cleanup
- Patrycja Makoś-Chełstowska
- Edyta Słupek
2023 SEPARATION AND PURIFICATION TECHNOLOGY
The extensive extraction of oil from the bottom of seas and oceans and its transportation by tankers increase the risk of potential environmental disasters associated with hydrocarbon fractions entering water reservoirs. Therefore, this paper presents the preparation of a simple impregnation of a melamine sponge with deep eutectic solvents (DES), which can be obtained from natural sources, including coconut oil, palm kernel oil, seed oils, mammalian milk, and substances commonly used in pharmacological and physiological studies. A preselection method based on the COSMO-RS model was used to select the most suitable DES among 760 solvents. The selected DES were prepared and impregnated on melamine sponge (MS). Structural and surface analyses were performed by DES-MS. The process parameters that affect the sorption capacity of DES-MS and the affinity tests were performed for specific oil groups. The highest absorption capacities were obtained for MS impregnated with tetraethylammonium chloride and decanoic acid in a 1:2 M ratio. The prepared new DES-MS were characterized by very high sorption capacities ranging from 40.9 to 99.8 g/g, as well as superhydrophobicity (water contact angle 151°), superoleophobicity (oil contact angle 0°), low density (0.177 g/cm3), high porosity (88.25 %), high thermal, mechanical, and chemical stability, and the possibility of multiple regenerations without loss of sorption capacity. In addition, the preparation of DES-MS is simple and involves little time and consumption of toxic organic solvents. These results indicate that DES-MS may be a “green” and low-cost alternative to current approaches for removing oil from water.
Suppressors of lapC mutation identify new regulators of LpxC, which mediates the first committed step in lipopolysaccharide biosynthesis
- Akshay Maniyeri Suresh
- Alicja Wieczorek
- Aravind Ayyolath
- Weronika Sugalska
- Gracjana Klein-Raina
- Satish Raina
2023 Pełny tekst INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
Gram-negative bacteria, such as Escherichia coli, are characterized by an asymmetric outer membrane (OM) with lipopolysaccharide (LPS) located in the outer leaflet and phospholipids facing the inner leaflet. E. coli recruits LPS assembly proteins LapB, LapC and LapD in concert with FtsH protease to ensure a balanced biosynthesis of LPS and phospholipids. We recently reported that bacteria either lacking the periplasmic domain of the essential LapC protein (lapC190) or in the absence of LapD exhibit an elevated degradation of LpxC, which catalyzes the first committed step in LPS biosynthesis. To further understand the functions of LapC and LapD in regulating LPS biosynthesis, we show that the overproduction of the intact LapD suppresses the temperature sensitivity (Ts) of lapC190, but not when either its N-terminal transmembrane anchor or specific conserved amino acids in the C-terminal domain are mutated. Moreover, overexpression of srrA, marA, yceJ and yfgM genes can rescue the Ts phenotype of lapC190 bacteria by restoring LpxC amounts. We further show that MarA-mediated suppression requires the expression of mla genes, whose products participate in the maintenance of OM asymmetry, and the SrrA-mediated suppression requires the presence of cardiolipin synthase A.
Surfactants application in sample preparation techniques: Insights, trends, and perspectives
- Khrystyna Vakh
- Stanislawa Koronkiewicz
2023 TRAC-TRENDS IN ANALYTICAL CHEMISTRY
Since the implementation of Green Chemistry into analytical practice, significant efforts have been made to improve the sustainability of chemical analysis. These include reducing the use of hazardous chemicals and solvents, minimizing waste, and improving energy efficiency. Surfactants can be applied in chemical analysis as an environmentally friendly alternative to conventional solvents and chemicals. The use of surfactants can increase extraction efficiency by improving solubility, increasing selectivity, and reducing organic solvent consumption. In addition, surfactants can also reduce interference with the sample matrix and improve limits of detection. This review covers recent developments in surfactant-based extraction techniques, highlighting the use of surfactants in both liquid-phase and solid-phase extraction. The main principles of surfactant-based extraction methods are discussed, as well as their application as assisting agents or surface modifiers. The effects of deep eutectic solvents on surfactants micellization and the application of biocompatible surfactants are also discussed.