In vitro selection of functional lantipeptides

In this report we present a method to identify functional artificial lantipeptides. In vitro translation coupled with an enzyme-free protocol for posttranslational modification allows preparation of more than 10(11) different lanthionine containing peptides. This diversity can be searched for functional molecules using mRNA-lantipeptide display. We validated this approach by isolating binders toward Sortase A, a transamidase which is required for virulence of Staphylococcus aureus. The interaction of selected lantipeptides with Sortase A is highly dependent on the presence of a (2S,6R)-lanthionine in the peptide and an active conformation of the protein.     

On the birational anabelian program initiated by Bogomolov I

Recall that a program initiated by Bogomolov in 1990 aims at reconstructing function fields K|k with td(K|k)>1 and k algebraically closed from the maximal pro-ℓ abelian-by-central Galois group P^c  _K\Pi ^{\hbox to1pt{}{\rm c}_{\phantom {g}}}_{K} of K, where ℓ is any prime number ≠char(k). In this paper we complete that program in the case k is an algebraic closure of a finite field.     

Controlled/Living Surface‐Initiated ATRP of Antifouling Polymer Brushes from Gold in PBS and Blood Sera as a Model Study for Polymer Modifications in Complex Biological Media

The use of PBS, 10% FBS or 10% CS as media for SI‐ATRP is reported. Controlled/living SI‐ATRP of MeOEGMA in PBS is achieved leading to better control than in water. The livingness is confirmed by chain extension with MeOEGMA or carboxybetaine acrylamide. This technique is successfully adopted for the polymerization of MeOEGMA in 10% FBS or CS as models for complex biological media with reasonable control of the brush growth. All prepared brushes show excellent antifouling properties.

     

Epicatechin B-ring conjugates: first enantioselective synthesis and evidence for their occurrence in human biological fluids

Herein, the first enantioselective total synthesis of a number of biologically relevant (-)-epicatechin conjugates is described. The success of this synthesis relied on (i) optimized conditions for the stereospecific cyclization step leading to the catechin C ring; on (ii) efficient conjugation reactions; and on (iii) optimized deprotection sequences. These standard compounds have been subsequently used to elucidate for the first time the pattern of (-)-epicatechin conjugates present in four different human biological fluids following (-)-epicatechin absorption.     

Shunting yard operations: Theoretical aspects and applications

Almost ever since freight has been transported via rail, shunting yards (also called classification or marshaling yards) are operated in order to separate freight trains and reassemble new trains. The efficient use of shunting yards has a deep impact on the efficiency and reliability of rail freight services. Thus, much research on shunting yards has been published, starting from the 1950s. Lately, several publications mostly focusing on the sorting procedures have livened up research on shunting yards. This paper reviews the literature on the operational processes at shunting yards over the last 40 years and discusses the operational challenges of freight transshipment. The approaches are classified according to different sorting strategies which allows an easy access to the models for both, researchers and practitioners. The paper concludes with an overview on future research challenges.     

In-situ Raman spectroscopy used to study and control the initial growth phase of microcrystalline absorber layers for thin-film silicon solar cells

The continuous deposition of microcrystalline silicon has been monitored with in-situ Raman spectroscopy. The process and measurement settings were chosen such that one spectrum was taken during approximately 9 nm of layer growth. This allows observing the crystallinity in the initial growth phase of microcrystalline silicon absorber layers. The influence of different p-doped seed layers has been studied. Under constant deposition conditions, an initial decrease in crystallinity was observed over the first tens of nanometers. By profiling the process gas flows during the initial phase it was possible to reduce the amount of amorphous material that was detected during the initial phase of deposition.     

On the largest prime factor of numerators of Bernoulli numbers

We prove that for almost all $n$, the numerator of the Bernoulli number $B_{2n}$ is divisible by a large prime.     

A performance analysis of channel fragmentation in dynamic spectrum access systems

Dynamic Spectrum Access systems offer temporarily available spectrum to opportunistic users capable of spreading transmissions over a number of non-contiguous subchannels. Such methods can be highly beneficial in terms of spectrum utilization, but excessive fragmentation degrades performance and hence off-sets the benefits. To get some insight into acceptable levels of fragmentation, we present experimental and analytical results derived from a mathematical model. According to the model, a system operates at capacity serving requests for bandwidth by assigning a collection of one or more gaps of unused bandwidth to each request as bandwidth becomes available. Our main result is a proof that, even if fragments can be arbitrarily small, the system remains stable in the sense that the average total number of fragments remains bounded. Within the class of dynamic fragmentation models, including models of dynamic storage allocation that have been around for many decades, this result appears to be the first of its kind. In addition, we provide extensive experimental results that describe behavior, at times unexpected, of fragmentation as parameter values are varied. Different scanning rules for searching gaps of available spectrum, all covered by the above stability result, are also studied. Our model applies to dynamic linked-list storage allocation, and provides a novel analysis in that domain. We prove that, interestingly, a version of the 50?% rule of the classical, non-fragmented allocation model holds for the new model as well. Overall, the paper provides insights into the behavior of practical fragmentation algorithms.     

On the number of nonzero digits of the partition function

Let p(n) be the function that counts the number of partitions of n. Let b ≥ 2 be a fixed positive integer. In this paper, we show that for almost all n the sum of the digits of p(n) in base b is at least log n/(7log log n). Our proof uses the first term of Rademacher’s formula for p(n).