Humboldt University of Berlin

About: Humboldt University of Berlin is a education organization based out in Berlin, Germany. It is known for research contribution in the topics: Population & Transplantation. The organization has 33671 authors who have published 61781 publications receiving 1908102 citations. The organization is also known as: Humboldt-Universität zu Berlin & Universitas Humboldtiana Berolinensis.

Review of AdS/CFT Integrability: An Overview

Abstract: This is the introductory chapter of a review collection on integrability in the context of the AdS/CFT correspondence. In the collection we present an overview of the achievements and the status of this subject as of the year 2010.

Acidity Differences between Inorganic Solids Induced by Their Framework Structure. A Combined Quantum Mechanics/Molecular Mechanics ab Initio Study on Zeolites

Abstract: The influence of the zeolite framework type (FAU, CHA, MOR, MFI) and the crystallographic position on the acidity of zeolites is investigated. The most stable Bronsted acid sites of the high-silica frameworks are considered: O1−H (FAU), O1−H (CHA), Al4−O2(H)−Si (MOR), and Al7−O17(H)−Si4 (MFI, sinusoidal channel). The latter is compared with the less stable Al12-O24(H)-Si12 position (MFI, channel intersection). Both the heat of the deprotonation and the heat of ammonia adsorption are considered as measures of acid strength. A novel hybrid computational scheme is used that combines the quantum mechanical cluster description (QM) of the active site with interatomic potentials (Pot) for the periodic zeolite framework. Specifically, the Hartree−Fock method (QM) is combined with ab initio shell model potentials (Pot) for the zeolite framework and its interaction with ammonia and ammonium ions. Complete relaxation of the framework is possible within this scheme and long-range corrections to the reaction energie...

Thermosensitive Au-PNIPA yolk-shell nanoparticles with tunable selectivity for catalysis.

Abstract: Metallic nanoparticles have been the subject of intense research recently because of their catalytic properties, which may differ considerably from the bulk metal. As the free nanoparticles tend to aggregate and are difficult to handle in catalytic applications, colloidal carrier systems have been developed that encapsulate and stabilize the particles. 5] More recently, so-called smart carrier systems, such as thermosensitive microgels, have become the focus of research. These hybrids react on external stimuli and allow the catalytic properties to be altered accordingly. Thus, thermosensitive polystyrene (PS)-poly(N-isopropylacrylamide) (PNIPA) core–shell microgels were applied as the active nanoreactor for the immobilization of metal nanoparticles. The catalytic activity of immobilized metal nanoparticles can be tuned by the swelling and shrinking of the microgels. Liz-Marz n et al. have developed a AuPNIPA core–shell colloidal system. They found that the thermoresponsive PNIPA shell with limited cross-linking allows for particularly efficient control of the catalysis of encapsulated Au nanoparticles. Recently, yolk–shell structures that consist of a single metal nanoparticle within an inorganic or polymeric shell 19] have become the subject of intense research. These systems can be used to tune the catalytic activity of the enclosed nanoparticle by a suitable architecture of the shell. Yolk–shell structures have the clear advantages in that individual metal nanoparticles are enclosed in a compartment that prevents aggregation with other nanoparticles. Furthermore, the embedded gold nanoparticle has a free surface that is not blocked by any surface group or polymer compared to the Au-PNIPA core–shell system. Moreover, the permeability of the shell may be tuned to a certain extent. Therefore, yolk– shell systems may be regarded as true nanoreactors that allow the catalytic activity of single nanoparticles to be studied in a defined environment. Herein we present a thermosensitive yolk–shell system that uses temperature as a trigger for reaction. Figure 1a shows the underlying principle of these systems: A single Au nanoparticle is encapsulated in a hollow thermosensitive PNIPA shell. The porosity and the hydrophobicity of this shell can be tuned in a well-defined manner by temperature while the colloidal stability of the entire hybrid is fully maintained. We show this by monitoring the reduction of hydrophilic 4-

Lockdown, quarantine measures, and social distancing: Associations with depression, anxiety and distress at the beginning of the COVID-19 pandemic among adults from Germany.

Abstract: The COVID-19 pandemic is suggested to have a negative impact on mental health. To prevent the spread of Sars-CoV-2, governments worldwide have implemented different forms of public health measures ranging from physical distancing recommendations to stay-at-home orders, which have disrupted individuals' everyday life tremendously. However, evidence on the associations of the COVID-19 pandemic and public health measures with mental health are limited so far. In this study, we investigated the role of sociodemographic and COVID-19 related factors for immediate mental health consequences in a nationwide community sample of adults from Germany (N = 4335). Specifically, we examined the effects of different forms and levels of restriction resulting from public health measures (e.g. quarantine, stay-at-home order) on anxiety and depression symptomatology, health anxiety, loneliness, the occurrence of fearful spells, psychosocial distress and life-satisfaction. We found that higher restrictions due to lockdown measures, a greater reduction of social contacts and greater perceived changes in life were associated with higher mental health impairments. Importantly, a subjectively assumed but not an officially announced stay-at-home order was associated with poorer mental health. Our findings underscore the importance of adequate risk communication and targeted mental health recommendations especially for vulnerable groups during these challenging times.