Fabrication of pH-Responsive Zn2+-Releasing Glass Particles for Smart Antibacterial Restoratives

The on-demand release of antibacterial components due to pH variations caused by acidogenic/cariogenic bacteria is a possible design for smart antibacterial restorative materials. This study aimed to fabricate pH-responsive Zn²⁺-releasing glass particles and evaluate their solubilities, ion-releasing characteristics, and antibacterial properties in vitro. Three kinds of silicate-based glass particles containing different molar ratios of Zn (PG-1: 25.3; PG-2: 34.6; PG-3: 42.7 mol%) were fabricated. Each particle was immersed in a pH-adjusted medium, and the solubility and concentration of the released ions were determined. To evaluate the antibacterial effect, Streptococcus mutans was cultured in the pH-adjusted medium in the presence of each particle, and the bacterial number was counted. The solubility and concentration of Zn²⁺ released in the medium increased with a decrease in medium pH. PG-3 with a greater content of Zn demonstrated higher concentrations of released Zn²⁺ compared with PG-1 and PG-2. PG-2 exhibited bactericidal effects at pH 5.1, whereas PG-3 demonstrated bactericidal effects at pH values of 5.1 and 6.1, indicating that PG-3 was effective at inhibiting S. mutans even under slightly acidic conditions. The glass particle with 42.7 mol% Zn may be useful for developing smart antibacterial restoratives that contribute to the prevention of diseases such as caries on root surfaces with lower acid resistance.     

Die titrimetrische Bestimmung der Ortho-,Pyro- und Metaphosphors?ure

Ohne Zusammenfassung     

2‐Iso­propyl‐4‐methyl‐4‐phenyl‐1,2,3,4‐tetra­hydro­iso­quinoline‐1‐thione

The title compound, C₁₉H₂₁NS, is the photoproduct obtained from N‐iso­propyl‐N‐[(E)‐2‐phenyl­propenyl]­thio­benz­amide. Recrystallization showed a spontaneous resolution.     

Tensor force manifestations in ab initio study of the 2H(d,γ)4He, 2H(d,p)3H, and 2H(d,n)3He reactions

The (2)H(d,p)(3)H, (2)H(d,n)(3)He, and (2)H(d,γ)(4)He reactions are studied at low energies in a multichannel ab initio model that takes into account the distortions of the nuclei. The internal wave functions of these nuclei are given by the stochastic variational method with the AV8' realistic interaction and a phenomenological three-body force included to reproduce the two-body thresholds. The obtained astrophysical S factors are all in very good agreement with the experiment. The most important channels for both transfer and radiative capture are identified by comparing to calculations with an effective central force. They are all found to dominate thanks to the tensor force.     

Light Emitting Diodes Fabricated from Liquid Phase Epitaxial InAs/InAsxP1‐x‐ySby/InAsx'P1‐x'‐y'Sby' and InAs/InAs1‐xSbx Multi‐Layers

Mid‐infrared light emitting diodes (LED) in 3‐5μm wavelength range have been fabricated from InAs/InAs_xP_1‐x‐ySb_y/InAs_x'P_1‐x'‐y'Sb_y' composition graded layer and InAs/InAsSb multilayers. The heterostructures were grown by liquid phase epitaxy (LPE) between 600 and 520°C. An output power of 3.1 mW at 11K and of 10 μW at 300 K have been obtained under a peak current of 100 mA (50 % duty ratio) from InAsSb multilayers. Recombination mechanisms for these diodes were studied by temperature‐dependent emission spectra using Fourier transform infrared (FTIR) measurement system with double modulation. The output powers of the LEDs decrease rapidly at temperatures above 153 K suggesting that nonradiative and Auger recombinations are the main limitation of the device performance at high temperatures.     

Low-temperature 1H, 13C, 77Se,and 125Te NMR studies on the apical-apical ligand exchange via the hypervalent tellurium and selenium ate complexes [10-M-3(C3); M = Se,Te] in the reactions of diaryl tellurides and selenides with aryllithium reagents

Pentafluorophenyl phenyl telluride ( 1 ) and 3,5-dichloro-2,4,6-trifluorophenyl phenyl telluride ( 2 ) react with pentafluorophenyllithium or 3,5-dichloro-2,4,6-trifluorophenyllithium in THF at low temperatures to form the corresponding tellurium ate complexes ( A ) and ( B ) as sole intermediates in the ligand exchange on the hypervalent tellurium atom. The corresponding selenides ( 3 ) and ( 4 ) also react with identical aryllithium reagents in THF to form the discrete intermediates, selenium ate complexes ( C ) and ( D ), in the exchange reactions. In these ligand exchange reactions of tellurides and selenides, electron-withdrawing ligands occupy the apical positions and the exchange takes place between these apical-oriented groups. The low-temperature ¹H, ¹³C, ⁷⁷Se, and ¹²⁵Te NMR spectroscopic techniques are effective methods for detection of unstable tellurium and selenium ate complexes.