Accuracy of the modified tooth-supported 3D printing surgical guides based on CT, CBCT, and intraoral scanning in maxillofacial region: A comparison study.

BACKGROUND: Tooth-supported surgical guides have demonstrated superior accuracy compared with bone-supported guides. This study aimed to modify the fabrication of tooth-supported guides for compatibility with tumor resection procedures and investigate their accuracy. METHODS: Patients with tumors who underwent osteotomy with the assistance of modified tooth- or bone-supported surgical guides were included. Virtual surgical planning (VSP) was employed to align three dimensional (3D) models extracted from intraoperative computed tomography (CT) images. The distances and angular deviations between the actual osteotomy plane and preoperative plane were recorded. A comparative analysis of osteotomy discrepancies between tooth-supported and bone-supported guides, as well as among tooth-supported guides based on CT, cone-beam CT (CBCT), or intraoral scanner (IOS) was conducted. The factors influencing the precision of the guides were analyzed. RESULTS: Sixty patients with 81 resection planes were included in this study. In the tooth-supported group, the mean deviations in the osteotomy plane and angle were 1.39 mm and 4.30°, respectively, whereas those of the bone-supported group were 2.16 mm and 4.95°. In the tooth-supported isotype guide groups, the mean deviations of the osteotomy plane were 1.39 mm, 1.47 mm, 1.23 mm across CT, CBCT, and IOS, respectively. The accuracy of the modified tooth-supported guides remained consistent regardless of number and position of the teeth supporting the guide and location of the osteotomy lines. CONCLUSIONS: The findings indicate that the modified tooth-supported surgical guides demonstrated high accuracy in the maxillofacial region, contributing to a reduction in the amount of surgically detached soft tissue.

Copper-Catalyzed C4-selective Carboxylation of Pyridines with CO2 via Pyridylphosphonium Salts.

Pyridine motifs are widespread pharmacophores in many drugs. Installing various substituents through pyridine C-H bond functionalization is significant for new drug design and discovery. Developments of late-stage functionalization reactions enrich the strategies for selective functionalization of pyridines. However, late-stage C-H carboxylation of pyridines is a long-standing challenge, especially selectively carboxylation with CO2 on pyridine motifs. Herein, we describe a practical method for C4-H carboxylation of pyridines via one-pot C-H phosphination and copper-catalyzed carboxylation of the resulted phosphonium salts with CO2 . The reaction is conducted under mild conditions and compatible with multiple active groups and several pyridine drugs, providing diverse valuable isonicotinic acid compounds, demonstrating the application potential of this strategy.

Exploring Trimethyl-Phosphate-Based Electrolytes without a Carbonyl Group for Li-Rich Layered Oxide Positive Electrodes in Lithium-Ion Batteries.

Li-rich layered oxides (LLOs) are one of the most attractive next-generation positive electrode materials as a result of their high energy density and low cost. However, the deterioration of cycling stability observed in LLOs remains one of the fundamental obstacles to commercialization. Carbonate-based electrolytes reacting with oxygen radicals evolved from the lattice of LLOs is the chief cause of their poor cyclability. Herein, we construct no carbonyl group, trimethyl phosphate (TMP)-based electrolytes with a fluorinated ether co-solvent and apply them to investigate the electrochemical behaviors of LLO batteries. These electrolytes can capture active oxygen species; the initial reversible capacity of cells reaches 295.5 mAh g-1; and the capacity retention remains 96.7% after 100 cycles. In contrast, the capacity retention of cells using carbonate-based electrolytes is only 54.7% after 60 cycles. These results would provide the scientific basis and theoretical support for building electrolytes of LLOs with high properties in the future.

Ruthenium(II)-Catalyzed Grignard-Type Nucleophilic Addition of C(sp2)-H Bonds to Unactivated Aldehydes.

The Grignard-type nucleophilic addition of C(sp2)-H bonds to aldehydes catalyzed by high-oxidation-state transition metal complexes is limited to activated aldehydes. Herein, we report the first example of Grignard-type nucleophilic addition of C(sp2)-H bonds to unactivated aldehydes catalyzed by high-oxidation-state ruthenium(II). The reaction has mild reaction conditions and good functional group tolerance. The corresponding alcohol products are obtained in good to excellent yields.