A Nanoparticle Autocatalytic Sensor for Ag⁺ and Cu²⁺ Ions in Aqueous Solution with High Sensitivity and Selectivity and Its Application in Test Paper

A novel nanoparticle autocatalytic sensor for the detection of Ag+ and Cu2+ has been constructed based on the oxidative ability of Ag+ and Cu2+ toward o-phenylenediamine (OPDA). Ag+ and Cu2+ can be reduced to zerovalent silver and copper, respectively, and then such zerovalent Ag and Cu species form silver and copper nanoparticles that can catalyze the reaction between OPDA and Ag+ and Cu2+. In the reaction, OPDA is oxidized to 2,3-diaminophenazine (OPDAox), which has a fluorescence emission at 568 nm. Under the optimal conditions, Ag+ and Cu2+ can be detected in the concentration ranges from 60 nM to 60 μM and from 2.5 nM to 25 μM, respectively. Through this facile approach, Ag+ and Cu2+ can be detected down to 60 nM and 2.5 nM, respectively. In addition, the sensor is utilized for the detection of Ag+ and Cu2+ in sewage, and we have obtained very good results that are consistent with those of inductively coupled plasma–mass spectroscopy (ICP-MS). Moreover, such a nanoparticle autocatalytic sensor is applied to test paper for the detection of Ag+ and Cu2+ with the naked eye. With such test paper, Ag+ and Cu2+ could be detected at levels as low as 0.06 nmol and 0.3 nmol, respectively, with detection ranges of 0.06–60 nmol for Ag+ and 0.3–60 nmol for Cu2+, under the irradiation of UV light (365 nm). The test paper could be potentially used in the rapid detection of Ag+ and Cu2+ in real samples

Recycling without Fiber DegradationStrong Paper Structures for 3D Forming Based on Nanostructurally Tailored Wood Holocellulose Fibers

Cellulosic paper products based on sustainable resources are of interest as a replacement for petroleum-based plastics, for example, in packaging applications. Improvements are desired for mechanical performance, recyclability, and possibilities to shape fiber networks into complex geometries. Commercial bleached wood fibers from the kraft process have insufficient mechanical properties for many applications, even with beating and additives. In addition, mechanical properties of paper structures are significantly reduced after recycling. Here, recycling and 3D shaping performance of holocellulose fibers are compared with kraft fibers and investigated in the context of wood fiber tailoring for eco-friendly materials. Holocellulose fibers from wood are prepared by mild peracetic acid delignification for well-preserved nanostructures and hemicellulose content (28 wt %). Paper structures of about 50% porosity are prepared from both types of fibers by vacuum filtration and drying. Mechanical tensile tests are performed, and fracture surfaces are investigated. The effects of recycling on the fiber structure (chemical composition, morphology, and crystallite size in fibers) and mechanical paper properties are reported. 3D-shaping performance is studied using compression molding with a double-curved mold. Holocellulose paper structures showed much better mechanical properties than kraft fiber paper (Young’s modulus 10 GPa, ultimate tensile strength 100 MPa), as well as better recycling performance (only 26% decrease in strength after 5 cycles) and 3D formability. The well-preserved cellulose and hemicellulose components are important, as well as the homogeneity of the fiber cell wall nanostructure. This preserves the intrinsic mechanical properties of fibers, reduces hornification effects, and provides strong interfiber adhesion. Furthermore, the water-soluble hemicelluloses present at the cellulose–cellulose interface are able to facilitate recycling and 3D forming

Chemically Cross-Linked Cellulose Nanocrystal Aerogels with Shape Recovery and Superabsorbent Properties

Cellulose nanocrystals (CNCs) are entering the marketplace as new high-strength nanoadditives from renewable resources. These high aspect ratio particles have potential applications as rheological modifiers, reinforcing agents in composites, coatings, and porous materials. In this work, chemically cross-linked CNC aerogels were prepared based on hydrazone cross-linking of hydrazide and aldehyde-functionalized CNCs. The resulting aerogels were ultralightweight (5.6 mg/cm³) and highly porous (99.6%) with a bimodal pore distribution (mesopores <50 nm and macropores >1 μm). Chemically cross-linked CNC aerogels showed enhanced mechanical properties and shape recovery ability, particularly in water, compared to previous reports of physically cross-linked CNC aerogels. Specifically, the aerogel shape recovered more than 85% after 80% compression, even after 20 compress and release cycles. These CNC aerogels can absorb significant amounts of both water (160 ± 10 g/g of aerogel) and dodecane (72 ± 5 g/g of aerogel) with cyclic absorption capacity. We demonstrate that CNC aerogels can be used as superabsorbents and for oil/water separations and they may also find application as insulating or shock-absorbing materials. The cross-linking technology developed here presents new ways to design CNC networked structures and suggests an alternate route to incorporate CNCs into matrix materials, such as epoxies and foams

Preserving Cellulose Structure: Delignified Wood Fibers for Paper Structures of High Strength and Transparency

To expand the use of renewable materials, paper products with superior mechanical and optical properties are needed. Although beating, bleaching, and additives are known to improve industrially produced Kraft pulp papers, properties are limited by the quality of the fibers. While the use of nanocellulose has been shown to significantly increase paper properties, the current cost associated with their production has limited their industrial relevance. Here, using a simple mild peracetic acid (PAA) delignification process on spruce, we produce hemicellulose-rich holocellulose fibers (28.8 wt %) with high intrinsic strength (1200 MPa for fibers with microfibrillar angle smaller than 10°). We show that PAA treatment causes less cellulose/hemicellulose degradation and better preserves cellulose nanostructure in comparison to conventional Kraft pulping. High-density holocellulose papers with superior mechanical properties (Young’s modulus of 18 GPa and ultimate strength of 195 MPa) are manufactured using a water-based hot-pressing process, without the use of beating or additives. We propose that the preserved hemicelluloses act as “glue” in the interfiber region, improving both mechanical and optical properties of papers. Holocellulose fibers may be affordable and applicable candidates for making special paper/composites where high mechanical performance and/or optical transmittance are of interest

Mechanistic Insights into Electroreductive C–C Coupling between CO and Acetaldehyde into Multicarbon Products

Production of valuable multicarbon (C3+) products through the electrochemical CO2 and CO reduction reactions (CO2RR and CORR) is desirable; however, mechanistic understanding that enables C–C coupling beyond the self-coupling of CO to valuable products is lacking. In this work, we elucidate the C–C coupling mechanism between CO and acetaldehyde, a reactive intermediate in both CO2RR and CORR, via combined isotopic labeling and in situ spectroscopic investigations. CO attacks the carbonyl carbon of acetaldehyde in the coupling, and the carbon in CO ends up in the hydroxymethyl group (−CH2OH) of the produced 1-propanol. While the coupling between CO and acetaldehyde does occur when the CORR is conducted with added acetaldehyde, only a minor fraction (up to 36%) of 1-propanol is from this pathway, and the majority of it is produced in the CORR by the self-coupling among CO. The adsorbed methylcarbonyl is proposed as the likely intermediate where the reaction pathway bifurcates to C2 and C3 products; i.e., it could either be hydrogenated to acetaldehyde and ethanol or couple with CO leading to the formation of 1-propanol

Bibliometric analysis of scientific papers on adverse reactions to COVID-19 vaccines published between 2019 and 2023

The Coronavirus Disease 2019 (COVID-19) pandemic has now persisted globally for four years, resulting in a staggering death toll of over 4 million individuals. The COVID-19 vaccine has emerged as a highly effective tool in controlling the spread of this virus. However, as the number of individuals receiving COVID-19. In this context, the investigation of adverse reactions related to COVID-19 vaccines holds paramount importance in relevant research. The purpose is to evaluate the current research status regarding adverse reactions associated with COVID-19 vaccines, offering insights for future research. A total of 3,746 articles were included in this analysis, and there has been a notable upward trajectory in the volume of published articles. The CiteSpace v6.1.R6, VOSviewer, SCImago Graphica, and Excel 2019 were employed to analyze and visualize the results. The institutions, countries, journals, authors, co-cited references, and keywords of these articles were analyzed. Furthermore, this study delves into the characteristics of articles on adverse reactions associated with COVID-19 vaccines. It was observed that the number of studies on COVID-19 vaccines has increased year by year since 2019 and witnessed a surge in output in 2021. The vast majority of studies have affirmed the overall safety of COVID-19 vaccines, with adverse reactions tending to be more concentrated in specific diseases. These findings provide valuable ideas for future research in this field and suggest the importance of strengthening international cooperation on adverse reactions to COVID-19 vaccines.</p

Injectable Polysaccharide Hydrogels Reinforced with Cellulose Nanocrystals: Morphology, Rheology, Degradation, and Cytotoxicity

Injectable hydrogels based on carboxymethyl cellulose and dextran, reinforced with rigid rod-like cellulose nanocrystals (CNCs) and aldehyde-functionalized CNCs (CHO–CNCs), were prepared and characterized. The mechanical properties, internal morphology, and swelling of injectable hydrogels with unmodified and modified CNCs at various loadings were examined. In all cases, gelation occurred within seconds as the hydrogel components were extruded from a double-barrel syringe, and the CNCs were evenly distributed throughout the composite, as observed by scanning and transmission electron microscopy. When immersed in purified water or 10 mM PBS, all CNC-reinforced hydrogels maintained their original shape for more than 60 days. The maximum storage modulus was observed in hydrogels with 0.250 wt % of unmodified CNCs and 0.375 wt % of CHO–CNCs. CHO–CNCs acted as both a filler and a chemical cross-linker, making the CHO–CNC-reinforced hydrogels more elastic, more dimensionally stable, and capable of facilitating higher nanoparticle loadings compared to hydrogels with unmodified CNCs, without sacrificing mechanical strength. No significant cytotoxicity to NIH 3T3 fibroblast cells was observed for the hydrogels or their individual components. These properties make CNC-reinforced injectable hydrogels of potential interest for various biomedical applications such as drug delivery vehicles or tissue engineering matrices