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 & Medicine. 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.

Antigen processing by the proteasome

Abstract: The proteasome is an essential part of our immune surveillance mechanisms: by generating peptides from intracellular antigens it provides peptides that are then 'presented' to T cells. But proteasomes--the waste-disposal units of the cell--typically do not generate peptides for antigen presentation with high efficiency. How, then, does the proteasome adapt to serve the immune system well?

Dirac Operators in Riemannian Geometry

Abstract: Clifford algebras and spin representation Spin structures Dirac operators Analytical properties of Dirac operators Eigenvalue estimates for the Dirac operator and twistor spinors Seiberg-Witten invariants Principal bundles and connections Bibliography Index.

Two-Dimensional Nanostructured Materials for Gas Sensing

Abstract: Two-dimensional (2D) nanostructures are highly attractive for fabricating nanodevices due to their high surface-to-volume ratio and good compatibility with device design. In recent years 2D nanostructures of various materials including metal oxides, graphene, metal dichalcogenides, phosphorene, BN and MXenes, have demonstrated significant potential for gas sensors. This review aims to provide the most recent advancements in utilization of various 2D nanomaterials for gas sensing. The common methods for the preparation of 2D nanostructures are briefly summarized first. The focus is then placed on the sensing performances provided by devices integrating 2D nanostructures. Strategies for optimizing the sensing features are also discussed. By combining both the experimental results and the theoretical studies available, structure-properties correlations are discussed. The conclusion gives some perspectives on the open challenges and future prospects for engineering advanced 2D nanostructures for high-performance gas sensors devices.

On elementary flux modes in biochemical reaction systems at steady state

Abstract: A mathematical definition of the concept of elementary mode is given so as to apply to biochemical reaction systems subsisting at steady state. This definition relates to existing concepts of null-space vectors and includes a condition of simplicity. It is shown that for systems in which all flux- have fixed signs, all elementary modes are given by the generating vectors of a convex cone and can, thus, be computed by an existing algorithm. The present analysis allows for the more general case that some reactions can proceed in either direction. Basic ideas on how to compute the complete set of elementary modes in this situation are outlined and verified by way of several examples, with one of them repraenting glycolysis and gluconeogenesis. These examples show that the elementary modes can be interpreted in terms of the particular biochemical functions of the network. The relationships to (futile) substrate cycles are elucidated.