Mechanical reinforcement of electrospun poly(vinyl alcohol) by α‐FeOOH nanowires

The authors kindly acknowledge the financial support of the Estonian Research Council for the post-doctoral research grants of personal research funding in projects PUT1096 and PUTJD578 as well as Institutional Research Funding Projects, IUT20-17, and IUT23-7.We report the mechanical performance of α‐FeOOH nanowire reinforced poly(vinyl alcohol) (PVA) composite nanofiber mat, fabricated using straightforward aqueous processing methods. Goethite (α‐FeOOH) nanocrystals have a high elastic modulus and –OH rich surface, ensuring strong interactions with hydrophilic polymers and effective reinforcement. Needle‐less electrospinning resulted in alignment of the nanowires along fibre axis, as confirmed by transmittance electron microscopy studies. Produced composite PVA nanofibers containing 10 wt% goethite nanoparticles exhibited an outstanding fivefold increase in Young's modulus and 2.5‐fold improvement of tensile strength compared to mats of neat PVA. The addition of α‐FeOOH had a significant influence on glass transition temperature indicating formation of interphase regions around nanowire inclusions. Observed properties are explained by nanowire grafting in the precursor solution, extensive interactions between the adsorbed PVA chains and the matrix and percolation of interphase regions at 10 wt% α‐FeOOH.Estonian Research Council PUT1096 and PUTJD578; Institutional Research Funding Projects, IUT20-17, and IUT23-7; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

BEHAVIOUR OF 1-BUTOXY-9-TETRADECYNE IN SUPERBASIC MEDA/EDA MEDIA

Abstract. The first example of the isomerization of a non-propargylic alkoxyalkyne, 1-butoxy-9-tetradecyne, in superbasic media MEDA/EDA (M = Li, Na) is presented. The extent of the competitive elimination reaction and the influence of the type of metal in superbase on the composition of product were determined

Zn Mediated Regioselective Barbier Reaction of Propargylic Bromides in THF/aq. NH4Cl Solution

Abstract: The reaction of substituted and unsubstituted propargylic bromides with butanal in presence of zinc power in THF/saturated aqueous NH4Cl solution gave corresponding allenic and propargylic alcohols with high selectivity

Recycling of Low-Quality Carbon Black Produced by Tire Pyrolysis

Pyrolysis is a promising way to reuse of waste tires. However, the carbon black generated in the process is often contaminated with various pyrolysis products. This study aims to recycle low-quality recycled carbon black (rCB) from waste tire pyrolysis, addressing the challenges posed by organic residues (up to 5 wt% bituminous substances, 112.2 mg/kg PAH). This causes the agglomeration of particles and decreases the active specific surface area. Cavitational vortex milling (both wet and dry) emerges as a promising method to valorize contaminated rCB, allowing for a significant reduction in the concentration of contaminants. This novel method allows for the generation of hydrophilic and hydrophobic black pigments. In parallel experiments, low-quality rCB is incorporated into solid biofuel to enhance its calorific value. The addition of 10 wt% rCB) to peat residues significantly elevates the calorific value from 14.5 MJ/kg to 21.0 MJ/kg. However, this improvement is accompanied by notable increases in CO2 and SO2 emissions. This dual effect underscores the necessity of considering environmental consequences when utilizing recycled carbon black as a supplement to solid biofuels. The findings provide valuable insights into the potential of cavitational vortex milling for carbon black valorization and highlight the trade-offs associated with enhancing biofuel properties through the addition of rCB

Efficient methodology for selective alkylation of hydrazine derivatives

Formation and use of a nitrogen dianion for selective hydrazine alkylation is reported. The scope and limitations of a new method were demonstrated. The novel method provides fast and easy access to substituted hydrazines, which are widely used as drugs, pesticides, and precursors for a variety of compounds in organic synthesis

Systematic synthesis of phthalimide-protected unsaturated hydrazine heterocycles

<p>A four-step route for the synthesis of novel phthalimide-protected hydrazine heterocycles that include a C˭C double bond in the cycle was developed. Phthalimide-protected Boc-hydrazine was used as a starting material, which was alkylated with bromoalkenes in mild conditions. Further steps involved Boc-deprotection and second alkylation with bromoalkenes. Finally, the heterocycles were produced by ring-closing metathesis. This route allows access to these versatile building blocks without using electrophilic amination or nitrosylation, therefore, significantly reducing environmental and safety concerns. Phthalimide-protected heterocycles can be derivatized further by modifying the carbon–carbon double bond and by deprotection and subsequent functionalization of the primary amino group. During the current research, various five- to seven-membered hydrazine heterocycles and numerous novel intermediate compounds were synthesized and thoroughly characterized.</p

The Functional Role of eL19 and eB12 IntersubunitBridge in the Eukaryotic Ribosome

During translation, the two eukaryotic ribosomal subunits remain associated through 17 intersubunit bridges, five of which are eukaryote-specific. These are mainly localized to the peripheral regions and are believed to stabilise the structure of the ribosome. The functional importance of these bridges remains largely unknown. Here the essentiality of the eukaryote-specific bridge eB12 has been investigated. The main component of this bridge is ribosomal protein eL19 which is composed of an N-terminal globular domain, a middle region and a long C-terminal α-helix. Analysis of deletion mutants demonstrated that the globular domain and middle region of eL19 are essential for cell viability, most likely functioning in ribosome assembly. The eB12 bridge, formed by contacts between the C-terminal α-helix of eL19 and 18S rRNA in concert with additional stabilising interactions involving either eS7 or uS17, is dispensable for viability. Nevertheless, eL19 mutants impaired in eB12 bridge formation displayed slow growth phenotypes, altered sensitivity/resistance to translational inhibitors and enhanced hyperosmotic stress tolerance. Biochemical analyses determined that the eB12 bridge contributes to the stability of ribosome subunit interactions in vitro. 60S subunits containing eL19 variants defective in eB12 bridge formation failed to form 80S ribosomes regardless of Mg(2+) concentration. The reassociation of 40S and mutant 60S subunits was markedly improved in the presence of deacetylated tRNA, emphasising the importance of tRNAs during the subunit association. We propose that the eB12 bridge plays an important role in subunit joining and in optimizing ribosome functionality