Development of chlorine dioxide sustained-release device using carboxymethyl cellulose-polyvinyl alcohol-ß-cyclodextrin ternary hydrogel and a new sustained-release kinetic model.

Owing to unique physiochemical and biological properties as well as the ability to be combined with a wide variety of materials for both biocompatibility and hydrophilia, carboxymethyl cellulose (CMC) is an excellent choice as a carrier. Loading Chlorine dioxide (ClO2) into biodegradable carrier for its good disinfection performance and high safety factors has attracted significantattention. Therefore, in this study, we used ClO2 as a model drug, and a sustained-ClO2-gas-release gel was developed from degradable materials, such as carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and ß-cyclodextrin (ßCD), through a simple and benign crosslinking strategy. Notably, the gel had sustained-release property in a wide temperature range of 4-35 â„ƒ and released ClO2 gas effectively for more than 30 days. Furthermore, a loss factor was proposed based on the incomplete release of the drug in the sustained release process to a chieve a good fit with the gas diffusion process. A new diffusion model was designed based on the Korsmeyer-Peppas model, and an excellent fit was obtained. This sustained-ClO2-gas-release gel provides theoretical and technical guidance for the development of sustained-disinfectant-release agents for use in space and offers new insights into the sustained release model of skeleton-soluble hydrogels. Supplementary Information: The online version contains supplementary material available at 10.1007/s10570-023-05070-6.

Synthesis and Characterization of Starch-Based Acid- and Alkali-Resistant Hydrogels Optimized by Box-Behnken Response Surface Methodology.

Applying gel-type solid chlorine dioxide for the sustained release of chlorine dioxide has several shortcomings, such as no resistance to acid and alkali corrosion and poor mechanical properties. However, introducing quaternary ammonium, carboxyl, and amino groups into the hydrogel system can enhance its acid and alkali resistance. In this study, the effects of concentration of dry heat-modified starch, quaternized carboxymethyl cellulose, and chitin on the swelling behavior and mechanical properties of starch-based acid- and alkali-resistant hydrogels are investigated. The feasibility of the actual and predicted values of the tentative results is verified based on the response surface design to determine the optimal concentration ratio of acid- and alkali-resistant hydrogels. The results reveal that optimized process parameters are reliable. The maximum swelling ratio and compressive stress of the hydrogel are 5358.00% and 44.45 kPa, respectively, and its swelling behavior conforms to the pseudo second-order kinetic model. Thus, the present study can provide a new method of developing efficient starch-based chlorine dioxide hydrogels for the sustained release of chlorine dioxide.

Synthesis and Optimization of a Free-Radical/Cationic Hybrid Photosensitive UV Curable Resin Using Polyurethane Acrylate and Graphene Oxide.

Cost-effective, practical, and efficiently performing photosensitive resin composite materials are essential, as the current materials are expensive, lack better alternatives, and do not meet 3D printing standards. In this study, based on orthogonal experiments for photosensitive resin curing, we prepared a free-radical/cationic hybrid photosensitive UV cured resin (UVR) using acrylic ester and epoxy resin as the prepolymers, tripropylenediol diacrylate (TPGDA) as the active diluent, and triaryl sulfonium salt (I-160) and 2,2-dimethyl-α-hydroxy acetophenone (1173) as the photoinitiators, in the optimized formula of acrylic-ester:epoxy-resin:TPGDA:I-160:1173 = 37.5:37.5:20:2.5:2.5. Further, we investigated the effects of polyurethane acrylates (PUA) and Graphene oxide (GO) on the surface morphology, chemical structure, hydrophobicity, mechanical strength, and gelation rate of the hybrid resin. We observed that 20% PUA improved tensile strength to the maximum of 36.89 MPa from 16.42 MPa of the unmodified hybrid resin, whereas 1% GO reduced volume shrinkage to the minimum of 2.89% from 3.73% of the unmodified hybrid resin. These photosensitive resins with higher tensile strength and lower volume shrinkage can be used to synthesize high performance functional materials in the future.

Intrinsic chirality and prochirality at Air/R-(+)- and S-(-)-limonene interfaces: spectral signatures with interference chiral sum-frequency generation vibrational spectroscopy.

We report in this work detailed measurements of the chiral and achiral sum-frequency vibrational spectra in the C-H stretching vibration region (2800-3050 cm(-1)) of the air/liquid interfaces of R-(+)-limonene and S-(-)-limonene, using the recently developed high-resolution broadband sum-frequency generation vibrational spectroscopy (HR-BB-SFG-VS). The achiral SFG spectra of R-limonene and S-limonene, as well as the RS racemic mixture (50/50 equal amount mixture), show that the corresponding molecular groups of the R and S enantiomers are with the same interfacial orientations. The interference chiral SFG spectra of the limonene enantiomers exhibit a spectral signature from the chiral response of the Cα-H stretching mode, and a spectral signature from the prochiral response of the CH(2) asymmetric stretching mode, respectively. The chiral spectral feature of the Cα-H stretching mode changes sign from R-(+)-limonene to S-(-)-limonene surfaces, and disappears for the RS racemic mixture surface. While the prochiral spectral feature of the CH(2) asymmetric stretching mode is the same for R-(+)-limonene and S-(-)-limonene surfaces, and also surprisingly remains the same for the RS racemic mixture surface. Therefore, the structures of the R-(+)-limonene and the S-(-)-limonene at the liquid interfaces are nevertheless not mirror images to each other, even though the corresponding groups have the same tilt angle from the interfacial normal, i.e., the R-(+)-limonene and the S-(-)-limonene at the surface are diastereomeric instead of enantiomeric. These results provide detailed information in understanding the structure and chirality of molecular interfaces and demonstrate the sensitivity and potential of SFG-VS as a unique spectroscopic tool for chirality characterization and chiral recognition at the molecular interface.

Bimetallic catalysts for hydrogen generation.

Research interest in bimetallic catalysts is mainly due to their tunable chemical/physical properties by a number of parameters like composition and morphostructure. In catalysis, numerous bimetallic catalysts have been shown to exhibit unique properties which are distinct from those of their monometallic counterparts. To meet the growing energy demand while mitigating the environmental concerns, numerous endeavors have been made to seek green and sustainable energy resources, among which hydrogen has been identified as the most promising one with bimetallic catalysts playing important roles. This tutorial review intends to summarize recent progress in bimetallic catalysts for hydrogen production, specifically focusing on that of reforming technologies as well as the relevant processes like water-gas shift (WGS) and CO preferential oxidation (PROX), and emphasizing on the fundamental understanding of the nature of catalytic sites responsible for generating high purity hydrogen and minimizing carbon monoxide formation. Meanwhile, some important synthesis and characterization methods of bimetallic catalysts developed so far are also summarized.

Morphologic evolution of Au nanocrystals grown in ionic liquid by plasma reduction.

Shape controlled Au nanocrystal growth in ionic liquid has been studied by glow discharge plasma reduction. In an 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF(4)]) solution with poly(vinyl pyrrolidone) (PVP) as surfactant, Au nanocrystals grow from faceted NPs to peanut-like particle aggregates, and eventually worm-like nanorods and nanowires as the growth time increases. This process is further found to be dependent on the concentration of employed surfactant. Based on systematic microscopic analysis and control experiments, a polymer-assisted oriented attachment mechanism is proposed to explain the observed morphologic evolution. Our work may have great implications for the employment of ionic liquids for shape controlled synthesis of nanocrystals.