Laser desorption/ionization-mass spectrometry for the analysis of interphases in lithium ion batteries.

Laser desorption/ionization-mass spectrometry (LDI-MS) is introduced as a complementary technique for the analysis of interphases formed at electrode|electrolyte interfaces in lithium ion batteries (LIBs). An understanding of these interphases is crucial for designing interphase-forming electrolyte formulations and increasing battery lifetime. Especially organic species are analyzed more effectively using LDI-MS than with established methodologies. The combination with trapped ion mobility spectrometry and tandem mass spectrometry yields additional structural information of interphase components. Furthermore, LDI-MS imaging reveals the lateral distribution of compounds on the electrode surface. Using the introduced methods, a deeper understanding of the mechanism of action of the established solid electrolyte interphase-forming electrolyte additive 3,4-dimethyloxazolidine-2,5-dione (Ala-N-CA) for silicon/graphite anodes is obtained, and active electrochemical transformation products are unambiguously identified. In the future, LDI-MS will help to provide a deeper understanding of interfacial processes in LIBs by using it in a multimodal approach with other surface analysis methods to obtain complementary information.

Mechanistic Origins of Regioselectivity in Cobalt-Catalyzed C(sp2)-H Borylation of Benzoate Esters and Arylboronate Esters.

Synthetic and mechanistic investigations into the C(sp2)-H borylation of various electronically diverse arenes catalyzed by bis(phosphine)pyridine (iPrPNP) cobalt complexes are reported. Borylation of various benzoate esters and arylboronate esters gave remarkably high selectivities for the position para to the functional group; in both cases, this regioselectivity was found to override the ortho to fluorine regioselectivity previously reported for (iPrPNP)Co borylation catalysts which arises from thermodynamic control of C(sp2)-H oxidative addition. Mechanistic studies support two distinct pathways that result in para-to-ester and para-to-boronate ester regioselectivity by thermodynamic and kinetic control, respectively, of C(sp2)-H oxidative addition. Borylation of a particularly electron-deficient fluorinated arylboronate ester resulted in acceleration of C(sp2)-H oxidative addition and concomitant inversion of regioselectivity, demonstrating that subtle changes in the relative rates of individual steps of the catalytic cycle can enable unique and switchable site selectivities.

Efficacy of a Culturally and Linguistically Competent Community Health Coach Intervention for Chinese with Hypertension.

Purpose: To develop and pilot test the efficacy of a culturally and linguistically sensitive, community health coach (CHC)-based intervention in Chinese immigrants in improving blood pressure control and medication adherence. Design: This study was conducted in 2017 with a cross-sectional design (n = 23). A CHC intervention was implemented using one 25-minute group educational presentation plus one 10-minute question and answer session at baseline, followed by four, 10-minute bi-weekly group question-and-answer sessions. Findings: There was a significant reduction in both systolic and diastolic blood pressure from baseline to week 8: Systolic BP -17.33 (±11.32) (p < 0.005) and diastolic BP -9.58 (±6.57) (p < 0.005). The mean score for medication adherence was 10.56 (±3.24) (possible range 3-15) at baseline and there was no significant change at week 8 (mean 10.89 ± 3.95) (p = 0.86). Conclusion: The CHC-based hypertension management program showed significant reductions in both systolic and diastolic blood pressures in Chinese immigrants. Since the proposed CHC-based hypertension management program is low cost and easy to establish, further investigation is recommended to generate more results for comparison. Practice Implications: There is potential for the CHC intervention to be implemented in clinical settings to help Chinese immigrants at large achieve optimal blood pressure control.

Visible-Light-Induced, Metal-Free Carbene Insertion into B-H Bonds between Acylsilanes and Pinacolborane.

Carbene insertion reactions with B-H bonds are a challenging but promising method for the synthesis of organoboranes. Herein, we report visible-light-induced B-H insertions of HBpin with acylsilane. This metal-free and operationally simple reaction proceeds in an atom-economical way with broad substrate scope under mild reaction conditions, affording a variety of important α-alkoxyorganoboronate esters in quantitative yields. Control experiments and density functional theory calculations suggest that the siloxycarbene generation from the T1 state of acylsilane and the carbene insertion into the B-H bond occurred in a concerted manner.

Palladium-Catalyzed Decarboxylative Heck-Type Coupling of Activated Aliphatic Carboxylic Acids Enabled by Visible Light.

The palladium-catalyzed coupling reaction of N-hydroxyphthalimide esters and styrenes to deliver exclusively (E)-substituted olefins under irradiation with visible light is reported. This method tolerates N-hydroxyphthalimide esters derived from primary, secondary, tertiary as well as benzylic carboxylic acids. Notably, Pd(PPh3 )4 is employed as an inexpensive palladium source and no addition of base or classical photocatalyst is required. Mechanistic studies suggest a light-mediated single-electron reduction of the activated acid by a photoexcited palladium(0) species to access alkyl radicals through decarboxylation.

Influence of surface and heat treatments on the flexural strength of a glass-infiltrated alumina/zirconia-reinforced dental ceramic.

OBJECTIVES: The purpose of this study was to investigate the influence of sandblasting, grinding, grinding orientation and polishing before and after heat treatment, on the flexural strength of a glass-infiltrated alumina/zirconia-reinforced dental ceramic (In-Ceram Zirconia). METHODS: The uniaxial flexural strength was calculated on 160 bar-shaped specimens (20 x 4 x 1.2mm) divided equally into eight groups as follows: sandblasted; sandblasted heated; polished; polished heated; ground parallel to the tensile axis; ground parallel heated; ground perpendicular; and ground perpendicular heated. Data were analyzed with multiple regression analysis, one-way ANOVA and Tukey's pairwise multiple comparisons and Weibull analysis. The treated and fractured surfaces were observed with SEM. The relative content of the monoclinic phase was quantified with an X-ray diffraction analysis. RESULTS: A thin layer of glass was present on the surface of the specimens after heat treatment and contributed to an improvement of the flexural strength. Surface treatment (not followed by heat treatment) generated phase transformation which, however, was not sufficient to avoid strength degradation caused by the flaws introduced with the surface treatments. Sandblasting caused the most marked strength degradation. Polishing alone increased the reliability, but did not improve the strength. The orientation of grinding in respect of the direction of the tensile stresses did not influence the ultimate tensile strength. SIGNIFICANCE: The present study suggests that any surface treatment performed on In-Ceram Zirconia should always be followed by heat treatment to avoid strength degradation.

Influence of surface and heat treatments on the flexural strength of Y-TZP dental ceramic.

OBJECTIVE: The aim of the investigation was to assess the influence of sandblasting, grinding, grinding orientation, polishing and heat treatment on the flexural strength of a yittria stabilized tetragonal zirconia polycrystals ceramic (Y-TPZ). METHODS: The specimens (160 beams) were equally divided into four groups according to the surface treatment (sandblasted, polished, ground parallel to the tensile axis, ground perpendicular). Twenty specimens from each group underwent heat treatment under the firing conditions used to fire a layer of porcelain and glaze. After treatment, the three-point flexure test was used to calculate the flexural strength and X-ray diffraction analysis was used to estimate the relative amount of monoclinic phase. The reliability of strength was assessed through the Weibull distribution. Statistical analysis was conducted with multiple regression analysis, one-way ANOVA and Tukey's pairwise multiple comparisons. Treated and fractured surfaces were observed with SEM. RESULTS: The following values of strength and relative content of monoclinic phase of zirconia were measured for each group: sandblasted (1540MPa; 9.5%); ground parallel (1330MPa; 8.3%); ground perpendicular (1525MPa; 8.3%); ground parallel and heated (1225MPa; monoclinic content not detectable); ground perpendicular and heated (1185MPa; monoclinic content not detectable); polished and heated (1165MPa; monoclinic content not detectable); polished (1095MPa; 0.8%); sandblasted and heated (955MPa; 0.3%). CONCLUSIONS: The present study suggests that sandblasting and grinding may be recommended to increase the strength of dental Y-TZP, provided they are not followed by heat treatment. Fine polishing may remove the layer of compressive stresses and therefore, lower the mean flexural strength.

Strength, reliability and mode of fracture of bilayered porcelain/zirconia (Y-TZP) dental ceramics.

The aim of this study was to investigate the biaxial flexural strength, reliability and the mode of fracture of bilayered porcelain/zirconia (Y-TZP) disks. For this purpose, 80 specimens were made from conventional dental porcelain and Y-TZP core ceramic, and equally divided into four groups as follows: monolithic specimens of porcelain; monolithic specimens of core material; bilayered specimens with the porcelain on top (facing the loading piston during testing); bilayered specimens with core material on top. The maximum load at fracture was calculated with a biaxial flexural test and finite element analysis was used to estimate the maximum tensile stress at fracture. Results were analyzed with one-way ANOVA, Tukey HSD. The reliability of strength was analyzed with the Weibull distribution. SEM was used to identify the initial crack and characterize the fracture mode. Monolithic core specimens and bilayered sample with the core material on the bottom were statistically significantly stronger than monolithic porcelain disks and bilayered samples with the porcelain on the bottom. The study, which was conducted with sample configurations that reproduce the clinical situation of crowns and fixed partial dentures, indicates that the material which lies on the bottom surface dictates the strength, reliability and fracture mode of the specimens. The contribution of strong and tough core materials to the performance of all-ceramics restorations may be offset by the weaker veneering porcelain if the actual distribution of the tensile stresses within the restoration is not taken into consideration.

Influence of grinding, sandblasting, polishing and heat treatment on the flexural strength of a glass-infiltrated alumina-reinforced dental ceramic.

The influence of processing-introduced flaws and heat treatment on the strength degradation of the dental core material has recently been observed. However, there are insufficient studies which investigate the role of grinding, grinding orientation, sandblasting, polishing and heat treatment on the strength of In-Ceram Alumina (IA), one of the most used glass-infiltrated alumina-reinforced dental core ceramics. To address these issues, the uniaxial flexural strength and reliability of eight groups of specimens (sandblasted, ground parallel to the tensile axis, ground perpendicular, and polished with and without heat treatment) were assessed. Statistical analyses indicate that heat treatment significantly improved the flexural strength of the material regardless of the surface treatment. Conversely, any surface treatment caused strength degradation, if it was not followed by heat treatment. Sandblasting caused the most marked strength degradation. Polishing alone (without heat treatment) did not strengthen the ceramic. The orientation of grinding in respect of the direction of the tensile stresses did not influence the ultimate tensile strength. The present study suggests that, in the case of IA, sandblasting, grinding and polishing should always be followed by heat treatment in order to avoid strength degradation of the material.