Li+/H+ exchange of Li7La3Zr2O12 single and polycrystals investigated by quantitative LIBS depth profiling

Li7La3Zr2O12 (LLZO) garnets are highly attractive to be used as solid electrolyte in solid-state Li batteries. However, LLZO suffers from chemical interaction with air and humidity, causing Li+/H+ exchange with detrimental implication on its performance, processing and scalability. To better understand the kinetics of the detrimental Li+/H+ exchange and its dependence on microstructural features, accelerated Li+/H+ exchange experiments were performed on single crystalline and polycrystalline LLZO, exposed for 80 minutes to 80 °C hot water. The resulting chemical changes were quantified by analytical methods, i.e. inductively coupled plasma optical emission spectroscopy (ICP-OES) and laser induced breakdown spectroscopy (LIBS). From the time dependence of the Li+ enrichment in the water, measured by ICP-OES, a bulk interdiffusion coefficient of Li+/H+ could be determined (7 × 10−17 m2 s−1 at 80 °C). Depth dependent concentrations were obtained from the LIBS data for both ions after establishing a calibration method enabling not only Li+ but also H+ quantification in the solid electrolyte. Short interdiffusion lengths in the 1 μm range are found for the single crystalline Ga:LLZO, in accordance with the measured bulk diffusion coefficient. In polycrystalline Ta:LLZO, however, very long diffusion tails in the 20 μm range and ion exchange fractions up to about 70% are observed. Those are attributed to fast ion interdiffusion along grain boundaries. The severe compositional changes also strongly affect the electrical properties measured by impedance spectroscopy. This study highlights that microstructural effects may be decisive for the Li+/H+ ion exchange kinetics of LLZO

Impact of Age and Body Site on Adult Female Skin Surface pH

Background: pH is known as an important parameter in epidermal barrier function and homeostasis. Aim: The impact of age and body site on skin surface pH (pH(SS)) of women was evaluated in vivo. Methods: Time domain dual lifetime referencing with luminescent sensor foils was used for pH(SS) measurements. pH(SS) was measured on the forehead, the temple, and the volar forearm of adult females (n = 97, 52.87 +/- 18.58 years, 20-97 years). Every single measurement contained 2,500 pH values due to the luminescence imaging technique used. Results: pH(SS) slightly increases with age on all three investigated body sites. There are no significant differences in pH(SS) between the three investigated body sites. Conclusion: Adult pH(SS) on the forehead, the temple and the volar forearm increases slightly with age. This knowledge is crucial for adapting medical skin care products. Copyright (C) 2012 S. Karger AG, Base

TIMolol Nasal Spray as a Treatment for Epistaxis in Hereditary Hemorrhagic Telangiectasia (TIM-HHT)—A Prospective, Randomized, Double-Blind, Controlled, Cross-Over Trial

To date, there is no approved local therapeutic agent for the treatment of epistaxis due to hereditary hemorrhagic telangiectasia (HHT). Several case reports suggest the topical use of timolol. This monocentric, prospective, randomized, placebo-controlled, double-blinded, cross-over study investigated whether the effectiveness of the standard treatment with a pulsed diode laser can be increased by also using timolol nasal spray. The primary outcome was severity of epistaxis after three months, while the main secondary outcome was severity of epistaxis and subjective satisfaction after one month. Twenty patients were allocated and treated, of which 18 patients completed both 3-month treatment sequences. Timolol was well tolerated by all patients. Epistaxis Severity Score after three months, the primary outcome measure, showed a beneficial, but statistically nonsignificant (p = 0.084), effect of additional timolol application. Epistaxis Severity Score (p = 0.010) and patients’ satisfaction with their nosebleeds after one month (p = 0.050) showed statistically significant benefits. This placebo-controlled, randomized trial provides some evidence that timolol nasal spray positively impacts epistaxis severity and subjective satisfaction in HHT patients when additively applied to standard laser therapy after one month. However, the effect of timolol was observed to diminish over time. Trials with larger sample sizes are warranted to confirm these findings

SARS-CoV2 evokes structural brain changes resulting in declined executive function

Background Several research has underlined the multi-system character of COVID-19. Though effects on the Central Nervous System are mainly discussed as disease-specific affections due to the virus’ neurotropism, no comprehensive disease model of COVID-19 exists on a neurofunctional base by now. We aimed to investigate neuroplastic grey- and white matter changes related to COVID-19 and to link these changes to neurocognitive testings leading towards a multi-dimensional disease model. Methods Groups of acutely ill COVID-19 patients (n = 16), recovered COVID-19 patients (n = 21) and healthy controls (n = 13) were prospectively included into this study. MR-imaging included T1-weighted sequences for analysis of grey matter using voxel-based morphometry and diffusion-weighted sequences to investigate white matter tracts using probabilistic tractography. Comprehensive neurocognitive testing for verbal and non-verbal domains was performed. Results Alterations strongly focused on grey matter of the frontal—basal ganglia—thalamus network and temporal areas, as well as fiber tracts connecting these areas. In acute COVID-19 patients, a decline of grey matter volume was found with an accompanying diminution of white matter tracts. A decline in executive function and especially verbal fluency was found in acute patients, partially persisting in recovered. Conclusion Changes in gray matter volume and white matter tracts included mainly areas involved in networks of executive control and language. Deeper understanding of these alterations is necessary especially with respect to long-term impairments, often referred to as ‘Post-COVID’

Li+/H+ exchange of Li7La3Zr2O12 single and polycrystals investigated by quantitative LIBS depth profiling

Li7La3Zr2O12 (LLZO) garnets are highly attractive to be used as solid electrolyte in solid-state Li batteries. However, LLZO suffers from chemical interaction with air and humidity, causing Li+/H+ exchange with detrimental implication on its performance, processing and scalability. To better understand the kinetics of the detrimental Li+/H+ exchange and its dependence on microstructural features, accelerated Li+/H+ exchange experiments were performed on single crystalline and polycrystalline LLZO, exposed for 80 minutes to 80 °C hot water. The resulting chemical changes were quantified by analytical methods, i.e. inductively coupled plasma optical emission spectroscopy (ICP-OES) and laser induced breakdown spectroscopy (LIBS). From the time dependence of the Li+ enrichment in the water, measured by ICP-OES, a bulk interdiffusion coefficient of Li+/H+ could be determined (7 × 10−17 m2 s−1 at 80 °C). Depth dependent concentrations were obtained from the LIBS data for both ions after establishing a calibration method enabling not only Li+ but also H+ quantification in the solid electrolyte. Short interdiffusion lengths in the 1 μm range are found for the single crystalline Ga:LLZO, in accordance with the measured bulk diffusion coefficient. In polycrystalline Ta:LLZO, however, very long diffusion tails in the 20 μm range and ion exchange fractions up to about 70% are observed. Those are attributed to fast ion interdiffusion along grain boundaries. The severe compositional changes also strongly affect the electrical properties measured by impedance spectroscopy. This study highlights that microstructural effects may be decisive for the Li+/H+ ion exchange kinetics of LLZO