Rapid SABRE Catalyst Scavenging Using Functionalized Silicas

In recent years the NMR hyperpolarisation method signal amplification by reversible exchange (SABRE) has been applied to multiple substrates of potential interest for in vivo investigation. Unfortunately, SABRE commonly requires an iridium-containing catalyst that is unsuitable for biomedical applications. This report utilizes inductively coupled plasma-optical emission spectroscopy (ICP-OES) to investigate the potential use of metal scavengers to remove the iridium catalytic species from the solution. The most sensitive iridium emission line at 224.268 nm was used in the analysis. We report the effects of varying functionality, chain length, and scavenger support identity on iridium scavenging efficiency. The impact of varying the quantity of scavenger utilized is reported for the three scavengers with the highest iridium removed from initial investigations: 3-aminopropyl (S1), 3-(imidazole-1-yl)propyl (S4), and 2-(2-pyridyl) (S5) functionalized silica gels. Exposure of an activated SABRE sample (1.6 mg mL−1 of iridium catalyst) to 10 mg of the most promising scavenger (S5) resulted in <1 ppm of iridium being detectable by ICP-OES after 2 min of exposure. We propose that combining the approach described herein with other recently reported approaches, such as catalyst separated-SABRE (CASH-SABRE), would enable the rapid preparation of a biocompatible SABRE hyperpolarized bolus.

Development and mechanical properties of three-dimensional flat-knitted fabrics with reinforcement yarns

Three-dimensional (3D) flat-knitted fabrics have become a topic of interest in the field of composites in recent years because of the growing need for rapid preparation of complicated shape preforms. In order to improve the mechanical properties of 3D flat-knitted fabrics, two types of 3D flat-knitted fabrics with reinforcement yarn (FKFR) were developed using ultra-high molecular weight polyethylene (UHMWPE) yarn. Their basic structures were composed of plain structure and interlock structure with tuck stitch, respectively, and the reinforcement yarn was integrated into the fabric as the weft inlay. The tensile, bending, drape, and bursting properties of the two fabrics were characterized. Results showed that the basic structure of the fabric has impacted on the mechanical properties of the fabric significantly. The tensile and bending properties of the fabric with interlock structure were better than that of the fabric with plain structure. During the transverse stretching process, the surface structure of the fabric with interlock structure was more stable. Moreover, transverse yarn strength utilization of the fabric with interlock structure was 1.05, which reached the level of ordinary woven fabric. In addition, the bursting force of the fabric with excellent tensile properties was lower than that of the fabric with a plain structure because the latter has better extensibility.

Rapid Preparation of Fluorescent Carbon Dots from Pine Needles for Chemical Analysis

Fluorescent carbon dots with blue, green, and red emissions were rapidly prepared from modified pine needles through microwave irradiation in a one-pot reaction. The fluorescence intensity and emission versatility for a carbon source were experimentally optimized. The reaction times were under 10 min and the reaction temperatures were lower than 220 °C. Potential applications of magnetic fluorescence-linked immunoassays of carcinoembryonic antigen (CEA) and tumor necrosis factor-alpha (TNF-α) were presented. The detection limits for CEA and TNF-α (3.1 and 2.8 pg mL−1, respectively) are lower than those presented in other reports, whereas the linear ranges for CEA and TNF-α (9 pg mL−1 to 18 ng mL−1 and 8.5 pg mL−1 to 17 ng mL−1, respectively) are wider than those presented in other reports. Magnetic immunoassays with fluorescent CDs prepared from pine needles can enable rapid, sensitive, and selective detections for biochemical analysis.

Tunable aziridinium ylide reactivity: non-covalent interactions enable divergent product outcomes

Methods for rapid preparation of densely functionalized and stereochemically complex N-heterocyclic scaffolds are in demand for exploring potential new bioactive chemical space. This work describes experimental and computational studies to better understand the features of aziridinium ylides as intermediates for the synthesis of highly substituted dehydromorpholines. The development of this chemistry has enabled the extension of aziridinium ylide chemistry to the concomitant formation of both a C–N and a C–O bond in a manner that preserves the stereochemical information embedded in the substrate. The chemistry is tolerant of a wide range of functionalities that can be employed for DNA-encoded library (DEL) synthesis to prepare diverse libraries of heterocycles with potential bioactivity. In addition, we have uncovered several key insights that describe the importance of steric effects, rotational barriers around the C–N bond of the aziridinium ylide, and non-covalent interactions (NCIs) on the ultimate reaction outcome. These critical insights will assist in the further development of this chemistry to generate novel and complex N-heterocycles that will further expand complex amine chemical space.

Microstructure and mechanical properties of melt-grown alumina-mullite/glass composites fabricated by directed laser deposition

Melt-grown alumina-based composites are receiving increasing attention due to their potential for aerospace applications; however, the rapid preparation of high-performance components remains a challenge. Herein, a novel route for 3D printing dense (< 99.4%) high-performance melt-grown alumina-mullite/glass composites using directed laser deposition (DLD) is proposed. Key issues on the composites, including phase composition, microstructure formation/evolution, densification, and mechanical properties, are systematically investigated. The toughening and strengthening mechanisms are analyzed using classical fracture mechanics, Griffith strength theory, and solid/glass interface infiltration theory. It is demonstrated that the composites are composed of corundum, mullite, and glass, or corundum and glass. With the increase of alumina content in the initial powder, corundum grains gradually evolve from near-equiaxed dendrite to columnar dendrite and cellular structures due to the weakening of constitutional undercooling and small nucleation undercooling. The microhardness and fracture toughness are the highest at 92.5 mol% alumina, with 18.39±0.38 GPa and 3.07±0.13 MPa·m1/2, respectively. The maximum strength is 310.1±36.5 MPa at 95 mol% alumina. Strength enhancement is attributed to the improved densification due to the trace silica doping and the relief of residual stresses. The method unravels the potential of preparing dense high-performance melt-grown alumina-based composites by the DLD technology.