The stress relaxation process in spread dipalmitoyl phosphatidyl glycerol (DPPG) monolayers was investigated by using the pendant drop technique as a microfilm balance in combination with the axisymmetric drop shape analysis. The stress relaxation caused by a transient drop volume change was analysed by a new model, which takes into account material inhomogeneity by means of a distribution of relaxation times. The surface pressure decay in the DPPG monolayers at 35 and 40 ºC is governed by 2 main relaxation times. One is of the order of 20 s, the other one is in the range of 200-600 s. The π/A isotherms, the surface dilational modulus, and the higher relaxation times are influenced by temperature and by the presence of electrolyte in the subphase; 0.15 mol dm -3 NaCl yields a smaller area demand per molecule in the monolayer. Harmonic oscillation experiments were carried out and the dilational elasticities and viscosities were determined for different frequencies in the range between the two main relaxation times. Both the elasticities and the viscosities, depend on frequency. The surface rheological behaviour is structurally viscous, i.e. high viscosities at small frequencies, which decrease at faster deformations. The results are related to the surface dilational rheological behaviour of dipalmitoyl phosphatidyl choline (DPPC) monolayers.
A high vaccination rate of older and particularly chronically ill people against coronavirus disease-2019 (COVID-19) is likely one of the most important factors in containing the pandemic. When Germany’s vaccination campaign started on December 2020, vaccination prioritization was initially carried out starting with older population groups. Side effect rates in 1065 individuals who had received the first dose of the messenger ribonucleic acid (mRNA) vaccine BNT162b2 Tozinameran from BioNTech/Pfizer three weeks earlier were examined retrospectively. An age- and gender-graded data analysis showed clear age and gender differences with regard to vaccine-related adverse effects. In 77% of all individuals over 80 years of age, no local or systemic side effects were reported after the first vaccination, whereas in the age group up to 80 years, only 37% showed no side effects. In the whole study population, 64% of females and 73% of males reported no adverse effects. The initial vaccination with mRNA vaccine BNT162b2 shows an overall low profile of side effects. Particularly in those over 80 years, an extraordinarily good tolerance with equally good effectiveness is evident. The sex comparison showed that women suffer more often from adverse vaccination reactions. In order to achieve sufficient herd immunity, both age- and gender-dependent vaccination reactions and any difference in the maintenance of immunity should be considered in future vaccination strategies.
The temperature behaviour of GaAdGaAIAs DQW-GRINSCH high-power laser diodes is calculated by means of a numerical model. The model includes a microscopic description of gain and spontaneous radiative recombination, a phenomenological description of interface and Auger recombination, and includes a pumping-current-dependent leakage. Based on the model, the temperature dependences of the macroscopic parameters of threshold current, external differential efficiency and wavelength are calculated. The resulting numerical values for these parameters are in excellent agreement with our experiments. Spontaneous radiative recombination is shown to be the dominant loss mechanism,
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