Hypercyclicity of the adjoint of weighted composition operators

In the present paper we investigate the hypercyclicity of the adjoint of weighted composition operator in special function spaces.     

Comparison Between the Induced Changes in the Intensities of Mid and Near Infrared Absorption Bands of Poly[Vinyl Alcohol] Due to Temperature and Solvents

The temperature induced changes in the intensities of the infrared absorption bands of PVA in both MID and NIR regions are presented. The absorption band at 1141cm^-1 is the only band among the bands in the mid region which is markedly affected by temperature. This band is taken as a measure of crystallinity of PVA. PVA shows two phase transitions at 80c⁰ and 120c⁰. The absorbances of the 1940nm in the near region is also temperature sensititve. The temperature dependence of the other bands in either mid or near regions is very weak. The effect of non polar and polar solvents such as n-hexane, carbon tetrachloride, toluene, chloroform, methanol and acetone is discussed. Comparison between the solvent induced changes in the intensities of the bands in mid and near regions is carried out. The data demonstrate that the bands in the near region ( overtone and combinations) are more sensitive to solvents than the bands in the mid regions. The combined effect of temperature and solvents on the intensities of absorption bands of PVA is also studied.     

Sorption of Hydrophobic Organic Compounds by Aqueous Latexes

Summary: Optical absorption measurements are used for the first time to investigate the uptake of pure organic solvents or solutions by latex particles. Sorption into glassy polymer particles is a two‐stage process with distinctly different characteristic times, which reflects that an initial softening of the outer particle layer facilitates further uptake. The sorption of solutions containing highly water‐insoluble compounds allows the preparation of composite nanoparticles, which are hardly accessible by other routes.

Photograph of the neat 100 nm latex (right) particles and the particles after dying by sorption with the hydrophobic pigment Sudan IV (left).     

Studies on pyrrolidinones. Preparation of 1,5,6‐10b‐tetrahydro‐2H‐pyrrolo[1,2‐c]quinazoline‐3‐ones from pyroglutamic acid

Tetrahydro‐2H‐pyrrolo[1,2‐c]quinazoline‐3‐ones are easily obtained from the Friedel‐Crafts cyclization of N‐arylaminomethyl pyroglutamic acids. This reaction occurrs via an acyliminium salt formed by decarboxylation of the acid function.     

Loading of ZIF-67 on silk with sustained release of iodine as biocompatible antibacterial fibers

Antibacterial fibers have great potential in numerous applications, including bandages, surgical robes, and surgical sutures, and play a significant role in our everyday lives. Here, zeolitic imidazolate framework-67 was synthesized using a green method on silk fibers through a layer-by-layer process under ultrasonic irradiation (ZIF-67@silk [U]) and without ultrasonic irradiation (ZIF-67@silk [B]). Then, iodine was loaded on ZIF-67@silk samples and were assessed as antibacterial fibers with iodine release. Four samples of ZIF-67@silk and I₂@ZIF-67@silk were characterized by FT-IR, PXRD, FE-SEM, TGA, BET, and UV–Vis spectroscopy. Finally, antibacterial activity of ZIF-67@silk (B and U) and I₂@ZIF-67@silk (B and U) on Staphylococcus aureus as Gram-positive bacteria and Escherichia coli as Gram-negative bacteria was investigated. In addition to ZIF-67@silk samples, iodine-loaded samples showed excellent antimicrobial facility.     

New Synthetic Route for Reaching Higher Phase Stabilization in LAMOX-Based Electrolyte for Solid Oxide Fuel Cells

S-substituted La₂Mo₂O₉ were synthesized by a solid-state procedure employing ammonium sulfate (NH₄)₂SO₄ as a sulfur source. The synthesized powders were examined using X-ray diffraction (XRD), thermogravimetric analysis (TGA), infrared, and Raman spectroscopies. The results divulged that the stabilization of the β-La₂Mo₂O₉ polymorph occurred in the interval of sulfur composition 0.1≤y≤0.6. This substitution generates a linear dwindling of the unit cell volume. The decomposition of all substituted samples started above 900 °C with a total weight loss linearly dependent on the sulfur content. Electrical studies confirmed that substituting S⁶⁺ for Mo⁶⁺ suppresses the phase transition of La₂Mo₂O₉ and stabilizes the cubic polymorph down to ambient temperature. It was also remarkable that this substitution caused a decrease in the conductivity, and unfortunately, none of the tested compositions allowed exceeding the conductivity of La₂Mo₂O₉. Infrared and Raman spectra confirmed the presence of the characteristic peaks of sulfates and molybdates groups.     

Converting Waste Plastic to Liquid Organic Hydrogen Carriers

The accumulation of waste plastics in landfills and the environment, as well as the contribution of plastics manufacturing to global warming, call for the development of new technologies that would enable circularity for synthetic polymers. Thus far, emerging approaches for chemical recycling of plastics have largely focused on producing fuels, lubricants, and/or monomers. In a recent study, Junde Wei and colleagues demonstrated a new catalytic system capable of converting oxygen-containing aromatic plastic waste into liquid organic hydrogen carriers (LOHCs), which can be used for hydrogen storage. The authors utilized Ru−ReO_x/SiO₂ materials with zeolite HZSM-5 as a co-catalyst for the direct hydrodeoxygenation (HDO) of oxygen-containing aromatic plastic wastes that yield cycloalkanes as LOHCs with a theoretical hydrogen capacity of ≈5.74 wt % under mild reaction conditions. Subsequent efficiency and stability tests of cycloalkane dehydrogenation over Pt/Al₂O₃ validated that the HDO products can serve as LOHCs to generate H₂ gas. Overall, their approach not only opens doors to alleviating the severe burden of plastic waste globally, but also offers a way to generate clean energy and ease the challenges associated with hydrogen storage and transportation.