Technical University of Berlin

About: Technical University of Berlin is a education organization based out in Berlin, Germany. It is known for research contribution in the topics: Quantum dot & Laser. The organization has 27292 authors who have published 59342 publications receiving 1414623 citations. The organization is also known as: Technische Universität Berlin & TU Berlin.

Introduction to the Algebraic Theory of Graph Grammars (A Survey)

Abstract: The aim of this survey is to motivate and introduce the basic constructions and results which have been developed in the algebraic theory of graph grammars up to now The complete material is illustrated by several examples, especially by applications to a "very small data base system", where consistent states are represented as graphs, operation rules and operations as productions and derivations in a graph grammar respectively Further applications to recursively defined functions, record handling, compiler techniques and development and evolution in Biology are sketched in the introduction This survey is divided into the following sections: 1 INTRODUCTION 2 GLUING CONSTRUCTIONS FOR GRAPHS 3 SEQUENTIAL GRAPH GRAMMARS 4 CHURCH-ROSSER PROPERTIES, PARALLELISM — AND CONCURRENCY THEOREMS 5 PROPERTIES OF DERIVATION SEQUENCES 6 PARALLEL GRAPH GRAMMARS 7 LOCALLY STAR GLUING FORMULAS 8 GRAPH LANGUAGES 9 APPENDIUM: CONCEPTS OF CATEGORY THEORY USED IN THE ALGEBRAIC THEORY OF GRAPH GRAMMARS 10 REFERENCES

Metal‐Doped Nitrogenated Carbon as an Efficient Catalyst for Direct CO2 Electroreduction to CO and Hydrocarbons

Abstract: This study explores the kinetics, mechanism, and active sites of the CO2 electroreduction reaction (CO2RR) to syngas and hydrocarbons on a class of functionalized solid carbon-based catalysts. Commercial carbon blacks were functionalized with nitrogen and Fe and/or Mn ions using pyrolysis and acid leaching. The resulting solid powder catalysts were found to be active and highly CO selective electrocatalysts in the electroreduction of CO2 to CO/H2 mixtures outperforming a low-area polycrystalline gold benchmark. Unspecific with respect to the nature of the metal, CO production is believed to occur on nitrogen functionalities in competition with hydrogen evolution. Evidence is provided that sufficiently strong interaction between CO and the metal enables the protonation of CO and the formation of hydrocarbons. Our results highlight a promising new class of low-cost, abundant electrocatalysts for synthetic fuel production from CO2 .

Effects of elevated (CO2) on photosynthesis in European forest species: a meta-analysis of model parameters

Abstract: The effects of elevated atmospheric CO2 concentration on growth of forest tree species are difficult to predict because practical limitations restrict experiments to much shorter than the average life-span of a tree. Long-term, processbased computer models must be used to extrapolate from shorter-term experiments. A key problem is to ensure a strong flow of information between experiments and models. In this study, meta-analysis techniques were used to summarize a suite of photosynthetic model parameters obtained from 15 field-based elevated [CO2] experiments on European forest tree species. The parameters studied are commonly used in modelling photosynthesis, and include observed light-saturated photosynthetic rates (Amax), the potential electron transport rate (Jmax), the maximum Rubisco activity (Vcmax) and leaf nitrogen concentration on mass (Nm) and area (Na) bases. Across all experiments, light-saturated photosynthesis was strongly stimulated by growth in elevated [CO2]. However, significant down-regulation of photosynthesis was also observed; when measured at the same CO2 concentration, photosynthesis was reduced by 10‐20%. The underlying biochemistry of photosynthesis was affected, as shown by a down-regulation of the parameters Jmax and Vcmax of the order of 10%. This reduction in Jmax and Vcmax was linked to the effects of elevated [CO2] on leaf nitrogen concentration. It was concluded that the current model is adequate to model photosynthesis in elevated [CO2]. Tables of model parameter values for different European forest species are given.