Harnessing Pb-S Interactions for Long-Term Water Stability in Cesium Lead Halide Perovskite Nanocrystals.

Lead halide perovskite nanocrystals (LHP NCs) have garnered attention as promising light-harvesting materials for optoelectronics and photovoltaic devices, attributed to their impressive optoelectronic properties. However, their susceptibility to moisture-induced degradation has hindered their practical applications. Despite various encapsulation strategies, challenges persist in maintaining their stability and optoelectronic performance simultaneously. Here, a ligand exchange approach is proposed using (11-mercaptoundecyl)-N,N,N-trimethylammonium bromide (MUTAB) to enhance the stability and dispersibility of CsPbBr3 (CPB) NCs in aqueous environments. MUTAB enables effective surface passivation of the CPB NCs via robust Pb-S interactions at the S-terminal while concurrently directing water molecules through the unbound cationic N-terminal or vice versa, ensuring water dispersibility and stability. Spectroscopic analysis confirms retained structural and optical integrity post-ligand exchange. Crucially, MUTAB-bound CPB NCs exhibit sustained charge transfer properties, demonstrated by aqueous colloidal oxidation reactions. This ligand exchange strategy offers a promising pathway for advancing LHP NCs toward practical optoelectronic and photocatalytic applications.

Insights into interfacial mechanisms: CsPbBr3 nanocrystals as sustainable photocatalysts for primary amine oxidation.

CsPbBr3 nanocrystals (NCs) employed as a photocatalyst resulted in efficient benzylamine oxidation under oxygen atmosphere. Improved reaction yields stem from favorable -NH2 functional group interactions on the NC surface, while additional interactions with -OMe or -SMe functional groups post-product formation result in lower yields. These insights into interfacial interactions and mechanistic aspects advance sustainable chemical transformations through cost-effective and recyclable CsPbBr3 NC-catalyzed primary amine oxidation.

Enhancing Photocatalytic Attributes of Perovskite Nanocrystals in Aqueous Media via Ligand Engineering.

The remarkable catalytic potential of perovskite nanocrystals (NCs) remains underutilized due to their limited stability in polar media, resulting from the vulnerability of their structure to disruption by polar solvents. In this study, we address this challenge by employing the bolaamphiphilic NKE-12 ligand, which features multiple denticities to effectively shield the surface of CsPbBr3 NCs from polar solvent interactions without compromising their light-harvesting properties. Our research, utilizing electrochemical impedance and photocurrent response measurements, highlights efficient charge separation and charge transfer enabled by NKE-12 ligands, which feature multiple ionic groups and peptide bonds, compared to conventional oleylamine/oleic acid ligands on CsPbBr3 NCs. Through the utilization of purely ligand-derived water-dispersed CsPbBr3/NKE-12 NCs, we successfully showcased their photocatalytic activity for acrylamide polymerization. A series of control experiments unveil a radical-based reaction pathway and suggest the synergistic involvement of photogenerated electrons and holes in producing the O2·- and OH· free radicals, respectively. Our findings emphasize the crucial role of ligand engineering in stabilizing perovskites in water and harnessing their exceptional photocatalytic attributes. This study opens new avenues for applying perovskite NCs in various catalytic processes in polar media.

Comparison of the incidence of postoperative pain in single sitting root canal treatment after using two reciprocating systems and two continuous rotary systems: An in vivo study.

Aim: The aim of the present study was to compare the incidence of postoperative pain in single sitting root canal treatment after using two reciprocating and two continuous rotating file systems. Methodology: One hundred and four permanent mandibular canine and first premolar teeth were selected for the study and were divided into two groups 1 and 2 comprising 52 teeth each. Group 1 was treated using reciprocating file systems and was subdivided into two subgroups A and B using WaveOne Gold (WOG) and Reciproc Blue (RB), respectively. Group 2 was treated using continuous rotating file systems and was divided into two subgroups A and B using One Curve (OC) and Vortex Blue (VB), respectively. Treatments were performed in a single sitting. After the visit, the patients were given a prescription for ibuprofen 400 mg to be taken every 6 h if they experience pain. Participants were asked to rate the intensity of the postoperative pain on a visual analog scale according to four classes (no pain, mild pain, moderate pain, and severe pain) after 24 h, 48 h, 72 h, and 7 days. Patients were also asked to record the number of prescribed analgesic medication tablets taken at these time points. Results: There was a statistically significant difference (P = 0.00) among the reciprocating file systems and continuous file systems regarding the incidence of postoperative pain after 24, 48, and 72 h which signifies that pain incidence and duration is less with respect to reciprocation instrumentation as compared to continuous instrumentation. Conclusion: The use of Reciproc instrumentation system (WOG and RB) showed significantly less intensity and duration of posttreatment pain compared to the single-file rotary system (OC and VB) in patients with symptomatic irreversible pulpitis with apical periodontitis.

Direct Pulp Capping with Mineral Trioxide Aggregate and Biodentine in Cariously Exposed Molar Teeth: 1-Year Follow-up - An In vivo Study.

Aim: To assess and compare the treatment outcome of direct pulp capping with mineral trioxide aggregate (MTA) and Biodentine, after complete excavation of caries in permanent dentition with a 2-visit treatment protocol. Materials and Methods: Direct pulp capping with white MTA was performed in 70 teeth. Direct pulp capping with Biodentine was also done in 72 teeth. In the subsequent visits after 2 weeks, pulp sensibility tests were attempted in both studied groups. All clinical outcomes were categorized as success or failure. Results: The success rate of the pulp capping procedure in the MTA group at the end of 12 months study was 94.3% in the Class I subgroup and 93.3% in the Class II subgroup. Conclusion: Direct pulp capping with MTA and Biodentine, after pulp exposure during excavation of deep caries could maintain pulp vitality in permanent teeth.

Efficacy of articaine versus mepivacaine administered as different supplementary local anesthetic techniques after a failed inferior alveolar nerve block with lidocaine in patients with irreversible pulpitis: An in vivo study.

Aim: The aim of the present study was to assess the efficacy of articaine versus mepivacaine administered as different supplementary local anesthetic techniques after a failed inferior alveolar nerve block (IANB) with lidocaine in patients with irreversible pulpitis. Materials and Methods: A total of 120 patients were included in the study. Patients were given IANB with 2 ml of 2% lidocaine hydrochloride with 1:80,000 epinephrine. Patients who showed subjective symptoms of IANB but did not secure pulpal anesthesia were randomly allocated to one of the following four groups by random sampling for supplementary local anesthesia - Group 1: buccal infiltration (BI) with 4% articaine with 1:100,000 epinephrine, Group 2: four-site intraligamentary (IL) injection with 4% articaine with 1:100,000 epinephrine, Group 3: BI with 2% mepivacaine with 1:100,000 epinephrine, and Group 4: four-site IL injection with 2% mepivacaine with 1:100,000 epinephrine. Results: Group 1 - BI with articaine provided anesthesia success in 27 cases (90%, n = 30). Group 2 - IL injection with articaine provided anesthesia success in 20 cases (66.67%, n = 30). Group 3 - BI with mepivacaine provided anesthesia success in 21 cases (70%, n = 30). Group 4 - IL injection with mepivacaine provided anesthesia success in 15 cases (50%, n = 30). A significant difference between the four groups was found. Conclusion: In patients with a mandibular first molar exhibiting symptomatic irreversible pulpitis, block injection with lidocaine along with supplemental BI with articaine allowed more pain-free treatments. Articaine showed better results when compared with mepivacaine.

A single-step, electrochemical synthesis of nitrogen doped blue luminescent phosphorene quantum dots.

Herein, we report a one-step strategy for the electrochemical synthesis of nitrogen doped blue luminescent phosphorene quantum dots (NPQDs) from black phosphorus at room temperature. Nitrogen percentage in NPQDs can be varied by the appropriate choice of solvent and supporting electrolyte. NPQDs [average size 6 ± 1.5 nm (N = 50)] obtained in this work exhibit ca. 88.7% quantum efficiency.