Zur Nachweisung von Phosphor in organischen Massen

Ohne Zusammenfassung     

Characterisation of the surface composition in electrospun nanowebs with static secondary ion mass spectrometry (S-SIMS)

Electrospinning is a recently rediscovered method to produce non-woven nanowebs of which the individual polymer fibres have diameters of 50-500 nm. Applications require specific functionalities to be present at the surface. The use of additives in the electrospun solution provides an elegant alternative to functionalised polymers. This study has focused on the use of the static secondary ion mass spectrometry (S-SIMS) to characterise the surface composition of nanofibres electrospun from acetone solutions containing 15% (w/w) of poly(?-caprolactone) (PCL, molecular weight 40,000) and 0-15 mol% (relative to PCL) cetyltrimethylammonium bromide (CTAB). Specifically, the calibration of the relative signal intensities of structural ions from PCL and CTAB as a function of the local concentrations requires adequate reference samples to be prepared. In general, this step becomes a major bottleneck in nanoscale analysis. A relatively simple method using a combination of spincoating and hand barcoating of solutions has been developed. Its applicability and limitations for monitoring the surface enrichment of CTAB in PCL nanowebs are discussed.     

Sparse partition universal graphs for graphs of bounded degree

In 1983, Chvátal, Trotter and the two senior authors proved that for any Δ there exists a constant B such that, for any n, any 2-colouring of the edges of the complete graph KN with N?Bn vertices yields a monochromatic copy of any graph H that has n vertices and maximum degree Δ. We prove that the complete graph may be replaced by a sparser graph G that has N vertices and edges, with N=⌈B^′n⌉ for some constant B^′ that depends only on Δ. Consequently, the so-called size-Ramsey number of any H with n vertices and maximum degree Δ is . Our approach is based on random graphs; in fact, we show that the classical Erd?s–Rényi random graph with the numerical parameters above satisfies a stronger partition property with high probability, namely, that any 2-colouring of its edges contains a monochromatic universal graph for the class of graphs on n vertices and maximum degree Δ.The main tool in our proof is the regularity method, adapted to a suitable sparse setting. The novel ingredient developed here is an embedding strategy that allows one to embed bounded degree graphs of linear order in certain pseudorandom graphs. Crucial to our proof is the fact that regularity is typically inherited at a scale that is much finer than the scale at which it is assumed.     

Weak quasi‐randomness for uniform hypergraphs

We study quasi‐random properties of k‐uniform hypergraphs. Our central notion is uniform edge distribution with respect to large vertex sets. We will find several equivalent characterisations of this property and our work can be viewed as an extension of the well known Chung‐Graham‐Wilson theorem for quasi‐random graphs. Moreover, let K_k be the complete graph on k vertices and M(k) the line graph of the graph of the k‐dimensional hypercube. We will show that the pair of graphs (K_k,M(k)) has the property that if the number of copies of both K_k and M(k) in another graph G are as expected in the random graph of density d, then G is quasi‐random (in the sense of the Chung‐Graham‐Wilson theorem) with density close to d. © 2011 Wiley Periodicals, Inc. Random Struct. Alg., 2011     

Density theorems and extremal hypergraph problems

We present alternative proofs of density versions of some combinatorial partition theorems originally obtained by E. Szemerédi, H. Furstenberg and Y. Katznelson. These proofs are based on an extremal hypergraph result which was recently obtained independently by W. T. Gowers and B. Nagle, V. Rödl, M. Schacht, J. Skokan by extending Szemerédi’s regularity lemma to hypergraphs.     

Base information content in organic formulas

Three questions are addressed concerning organic formulas at their most primitive level: (1) What is the information per atomic symbol? (2) What is the level of system redundancy? (3) How are high-information formulas distinguished from low-information ones? The results are simple yet interesting. Carbon chemistry embodies a code which is low in base information and high in redundancy, irrespective of database size. Moreover, code units associated with halocarbons, proteins, and polynucleotides are especially high in information. Low-information units are more often associated with simple alkanes, aromatics, and common functional groups. Overall, the work for this paper quantifies the base information content in organic formulas; this contributes to research on symbolic language, chemical information, and molecular diversity.     

Toward extracting $$\gamma $$ from $$B\rightarrow DK$$ without binning

SABRE (Sodium iodide with Active Background REjection) is a direct detection dark matter experiment based on arrays of radio-pure NaI(Tl) crystals. The experiment aims at achieving an ultra-low background rate and its primary goal is to confirm or refute the results from the DAMA/LIBRA experiment. The SABRE Proof-of-Principle phase was carried out in 2020–2021 at the Gran Sasso National Laboratory (LNGS), in Italy. The next phase consists of two full-scale experiments: SABRE South at the Stawell Underground Physics Laboratory, in Australia, and SABRE North at LNGS. This paper focuses on SABRE South and presents a detailed simulation of the detector, which is used to characterise the background for dark matter searches including DAMA/LIBRA-like modulation. We estimate an overall background of 0.72 cpd/kg/\(\hbox {keV}_{\hbox {{ee}}}\) in the energy range 1–6 \(\hbox {keV}_{\hbox {{ee}}}\) primarily due to radioactive contamination in the crystals. Given this level of background and considering that the SABRE South has a target mass of 50 kg, we expect to exclude (confirm) DAMA/LIBRA modulation at \(4~(5)\sigma \) within 2.5 years of data taking.