Lithium‐Ion Endohedral Fullerene (Li+@C60) Dopants in Stable Perovskite Solar Cells Induce Instant Doping and Anti‐Oxidation

Herein, we report use of [Li⁺@C₆₀]TFSI^? as a dopant for spiro‐MeOTAD in lead halide perovskite solar cells. This approach gave an air stability nearly 10‐fold that of conventional devices using Li⁺TFSI^?. Such high stability is attributed to the hydrophobic nature of [Li⁺@C₆₀]TFSI^? repelling moisture and absorbing intruding oxygen, thereby protecting the perovskite device from degradation. Furthermore, [Li⁺@C₆₀]TFSI^? could oxidize spiro‐MeOTAD without the need for oxygen. The encapsulated devices exhibited outstanding air stability for more than 1000 h while illuminated under ambient conditions.     

Velocity field after wave breaking

The velocity field in breaking water waves is considered in this paper. A numerical simulation describes in detail the transition from a primary overturning and consequent rebounding jets into a bore front, where the vorticity in the coherent large‐scale eddy structures devolves into turbulence. Spatial changes in the frequency spectra of the kinetic energy and the enstrophy are associated with the production, transport and dissipation of the Reynolds stress and the various wave and turbulent mixing length scales. Mean velocity fields and the wave and kinetic energy in a surf zone are evaluated. Fourier and wavelet spectral analysis is applied to study both the surface elevation and energy changes, and the distinction that must be made between spilling and plunging breakers is clarified in this paper. Copyright © 2002 John Wiley & Sons, Ltd.     

Phase transition of collagen and gelatin

Summary In order to investigate physical properties of semicrystalline high polymer, such as collagen or gelatin, over a wide temperature range, the phase change which might occur in this range is first of all required to elucidate. For this purpose, experiments seeking for the temperature dependence of linear thermal expansion, retractive stress, complex dynamic elasticity moduli, and equilibrium stress, the time rate of change of stress at constant temperatures, differential thermal analysis, and wide-angle X-ray diffraction analysis were performed on dried steer Achilles tendon fiber and gelatin film. The following conclusions were obtained. Tendon fiber consists of three regions of different structure: amorphous region having a second order phase transition point at 120 °C, less oriented unstable crystalline region having widely distributed melting temperatures over the range between 80–100° and 180 °C, and stable crystalline region having sharply distributed melting temperatures around 200 °C. Gelatin also consists of the same three regions, and the stable crystalline region is stabilized further by the higher degree of cross-linking having bonds of ionic nature and possesses its melting temperatures around 220 °C.

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Zusammenfassung Um physikalische Eigenschaften teilkristalliner Hochpolymerer wie Kollagen oder Gelatine zu untersuchen, wurde über einen weiten Temperaturbereich der Phasenwechsel, der in diesem Bereich eintritt, untersucht. Zu diesem Zweck wurde die Temperatur abh?ngigkeit der linearen thermischen Ausdehnung, die Zugkraft, der komplexe Elastizit?tsmodul, der Gleichgewichtszug, die Geschwindigkeit der ?nderung des Zugs bei konstanter Temperatur, ‘differential-thermoanalytische Daten und Weitwinkel-R?ntgenstreuung an getrockneter Stier-Achilles-Sehne und Gelatinefilm durchgeführt. Es ergaben sich folgende Schlüsse: Fasern der Sehnen bestehen aus drei Bereichen verschiedener Struktur: amorphen Bereichen, die einen Phasenübergang zweiter Ordnung bei 120 °C zeigen, weniger orientierten instabilen kristallinen Bereichen mit weit verteilten Schmelztemperaturen im Bereich zwischen 80–100 und 180 °C und stabilen kristallinen Bereichen mit scharf verteilten Schmelztemperaturen um 200° herum. Auch Gelatine besteht aus denselben drei Anteilen, und die stabilen kristallinen Bezirke sind au?erdem durch einen h?heren Grad von Vernetzung mit Bindungen ionischer Natur stabilisiert und besitzen Schmelztemperaturen um 220 °C.

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With 13 figures in 18 details and 1 table

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Dedicated to Prof. Dr. R. Hilsch for his 60th birthday.     

Mössbauer spectroscopic study of frozen solutions of57Co using a specially designed cryostat for time differential coincidence emission Mössbauer spectroscopy of237Np

Experiments on the⁵⁷Fe Mössbauer effect in frozen solutions were carried out in order to demonstrate the capabilities of a cryostat which was developed for the emission Mössbauer spectroscopy of²³⁷Np. We confirmed the existence of an aliovalent state of⁵⁷Fe in the temperature range from 5.5 to 35 K. However, the relative amounts of Fe(II) and Fe(III) in the frozen matrix were almost constant for the temperature range from 5.5 to 150 K. The design, operation and capabilities of the cryostat are also described.     

Vapor-liquid equilibria for polyisobutylene solutions

Vapor sorption isotherms in binary solutions of polyisobutylene (PIB), (M_η = 4.7 × 10⁶ g/mol) in hydrocarbons (cyclopentane; cyclohexane; n-heptane; 2,2-dimethyl butane; and 2,2,4-trimethyl pentane) and chlorinated methanes [carbon tetrachloride (CCI₄) and chloroform (CHCI₃)] have been determined at 23.5°C using the piezoelectric sorption method. The polymer-solvent interaction parameter χ obtained agrees with previously published values determined by using gas-liquid chromatography and a quartz-helix vapor sorption apparatus. The Flory theory of corresponding-states has been applied to the experimental results through the χ parameter and affords a good prediction of the concentration dependence of χ for solutions of chloroform, carbon tetrachloride, n-heptane, and 2,2-dimethyl butane in PIB. The experimental values of \documentclass{article}\pagestyle{empty}\begin{document}$ [\partial (a_1 /\psi _1 )/\partial a_1 ]_{T,P} $\end{document} for the PIB solutions are constant over the measured concentration range, for example \documentclass{article}\pagestyle{empty}\begin{document}$ [\partial (a_1 /\psi _1 )/\partial a_1 ]_{T,P} $\end{document} = ?4.1 for CCI₄, ?3.65 for CHCI₃, ?3.0 for 2,2-dimethyl butane and n-heptane, ?2.7 for 2,2,4-trimethyl pentane, ?2.7 for cyclohexane, and ?1.7 for cyclopentane, where a₁ is the solvent activity and ψ₁ is the solvent segment fraction. The correlations between the values of \documentclass{article}\pagestyle{empty}\begin{document}$ [\partial (a_1 /\psi _1 )/\partial a_1 ]_{T,P} $\end{document} and the theories of Guggenheim, Miller, Huggins, and Flory are discussed.     

The site distribution of Ti and V and the metal-metal interaction in the ternary system (V,Ti)5S8

The phase relations of the ternary system V_1?xTi_xS_1.57 are presented on the basis of X-ray diffractometry. The site distribution of Ti and V atoms in the structure is clarified through an NMR absorption study at room temperature. The phase relations and the site distribution of Ti and V, which appear to be closely related to each other, are discussed in terms of the metal-metal interaction of the face-shared octahedra in the metal-deficient distorted NiAs structure.     

The effect of polymer side chains on vapor sorption in polyacrylate and polymethacrylate solutions

The segment fraction Ψ₁ activity coefficients, a₁/Ψ₁, of solvents have been determined by the piezoelectric sorption method for 0.1 ≤ Ψ₁ ≤ 0.5 in binary solutions of chlorinated methanes [carbon tetrachloride (CCl₄), chloroform (CHCl₃), and dichloromethane (CH₂Cl₂)] with aromatic hydrocarbons (benzene and toluene) in poly(methyl methacrylate), poly(methyl acrylate), poly(ethyl methacrylate), and poly(n-butyl acrylate) at 23.5°C. The present results for toluene in PMMA agree with previously published values obtained by gas-liquid chromatography. For CCl₄ and the aromatic hydrocarbons, the polymer–solvent interaction parameter χ is positive and constant, while for the polar solvents (CHCl₃ and CH₂Cl₂), χ is negative and increases with increasing Ψ₁. The effect of the polymer side chains on vapor sorption in nonpolar and polar solvent systems is discussed in terms of the χ parameter.     

Vapor-liquid equilibria for polybutadiene and polyisoprene solutions

Vapor-liquid equilibria in binary solutions of hydrocarbons (n-hexane, benzene, toluene, cyclohexane) and chlorinated methanes [carbon tetrachloride (CCl₄), chloroform (CHCl₃), and dichloromethane (CH₂Cl₂)] in polybutadiene (PBD) and polyisoprene have been determined at 23.5°C by using the piezoelectric sorption method. The weight-fraction activity coefficient of solvent (a₁/w₁) in cis-PBD (98% cis-1,4 addition) and random cis-trans-PBD (r-PBD, 34.3% cis-1,4 addition; 54.3% trans-1,4 addition; 11.4% vinyl-1,2 addition) are almost equal for CCI₄, CHCI₃, CH₂CI₂, benzene, and toluene solutions, while the values of a₁/w₁ in n-hexane and cyclohexane solutions in cis-PBD are larger than those in r-PBD solutions. The values of a₁/w₁ for solutions of hydrocarbons and chlorinated methanes in cis-1,4 polyisoprene (95% cis-1,4 addition) have been compared with those for cis-PBD.