Comprehensive two‐dimensional GC for the analysis of low‐molecular‐weight oxygenates in three different matrices from a petrochemical pilot plant using a single calibration

A method using comprehensive ²DGC with flame ionisation detection was developed to quantify 17 low‐molecular‐weight oxygenates in three different matrices, namely water, oil and gas, using a single calibration. The method was required for the pilot‐plant experiments of a chemical process unit. From an analytical perspective, the first task was to find a suitable analytical method with sufficient selectivity and sensitivity to analyse the selected oxygenates at low levels in the presence of high levels of hydrocarbons. The second was the accurate quantitation of oxygenates in the water, oil and gas fractions, using the same instrument and calibration. Both these requirements were met by using comprehensive ²DGC in the inverse configuration and calibrating the detector with the number of moles injected versus response. The method was successfully applied for the characterisation of the reactor product stream of the chemical process unit and made it possible to determine the fate of the selected oxygenates after passing through the reactor. The development of the method and some of the results are described in this paper.     

Syntheses of 5′‐Nucleoside Monophosphate Derivatives with Unique Aminal,Hemiaminal, and Hemithioaminal Functionalities: A New Class of 5′‐Peptidyl Nucleotides

A number of synthetically useful transformations have been developed to generate novel 5′‐peptidyl nucleoside monophosphate analogues that incorporate sensitive phosphoaminal, ‐hemiaminal or ‐hemithioaminal functionalities. The strategies adopted entailed the coupling between dipeptides, which enclose a reactive Cα‐functionalized glycine residue and phosphate or phosphorothioate moieties. These developments led to potentially powerful and general methodologies for the preparation of α‐phosphorylated pseudopeptides as well as nucleoside monophosphate mimics. The resulting conjugates are of interest for a variety of important applications, which range from drug development to synthetic biology, as pronucleotides or artificial building blocks for the enzymatic synthesis of xenobiotic information systems. The potential of all dipeptide‐TMP conjugates as pyrophosphate mimics in the DNA polymerization reaction was tested, and the influence of the nature of the linker was evaluated by in vitro chain elongation assay in the presence of wild‐type microbial DNA polymerases.     

Loss reserving using loss aversion functions

This article discusses the determination of risk capital based on “aversion” functions. Aversion functions weigh different outcomes according to perceived severity. Many practical and popular risk measures are usefully viewed in terms of aversion functions including those arising from distortion operators and risk margin loadings. The approach of this paper builds on, unifies, and extends existing disparate approaches discussed in the literature. Analytical and computer generated illustrations are given as well as suggestions for the practical determination of aversion functions.     

Highly selective hydroaminomethylation of internal alkenes to give linear amines

The application of phenoxaphosphino-modified Xantphos-type ligands (1-9) in the rhodium-catalyzed hydroaminomethylation of internal olefins to give linear amines is reported. Excellent chemo- and regioselectivities have been obtained through the use of 0.1 mol % [Rh(cod)2]BF(4)/0.4 mol % xantphenoxaphos (1), providing a practical and environmentally attractive synthetic route for the preparation of amines from internal alkenes. For the first time, both functionalized internal olefins and mixtures of internal and terminal olefins have been converted highly selectively into linear amines. Investigations of the effects of the calculated natural bite angles of ligands on hydroaminomethylation shows that the regioselectivity for the linear product follows a similar trend to that seen in the hydroformylation of internal alkenes with the aid of these ligands. Hydroaminomethylation and each of its individual steps were monitored by high-pressure infrared spectroscopy. The results suggest that hydroaminomethylations take place by a sequential isomerization/hydroformylation/amination/hydrogenation pathway.     

General framework for testing Poisson‐Voronoi assumption for real microstructures

Modeling microstructures is an interesting problem not just in materials science, but also in mathematics and statistics. The most basic model for steel microstructure is the Poisson‐Voronoi diagram. It has mathematically attractive properties and it has been used in the approximation of single‐phase steel microstructures. The aim of this article is to develop methods that can be used to test whether a real steel microstructure can be approximated by such a model. Therefore, a general framework for testing the Poisson‐Voronoi assumption based on images of two‐dimension sections of real metals is set out. Following two different approaches, according to the use or not of periodic boundary conditions, three different model tests are proposed. The first two are based on the coefficient of variation and the cumulative distribution function of the cells area. The third exploits tools from to topological data analysis, such as persistence landscapes.     

Multiplying after the turn

In education multiplying is usually viewed as repeated joining together and dividing as repeated taking away or, which comes to the same thing, as an equal distribution. This presentation springs from Antiquity, when thought was mostly concrete. In modern mathematics we have relation-numbers instead of, image-numbers and likewise multiplying is a facet of relational thinking. The view that children merely can learn through the concrete is often biassedly understood in the sense that the concrete has to be abstracted, which characterizes substantial thinking. However, in the case of relational thinking, learning through the concrete means that to achieve insight the mathematical activities have to be applied to reality, a crucial point, for most people have difficulties with applying multiplication, much more than with, the inherent algorithms. It appears that they do not really know what multiplication is, particularly not its space structure. The more general the structure the more and wider the applications. This thesis infers that multiplying as multiple of classes is much less useful than multiplying as space form. Questing for the essence of multiplication is the major topic of this paper. Which changes has its structure undergone and how can education deal with them? At the end it is illustratively explained why probability, based on the established multiplication, is usually such a tough domain.     

Structure–Activity Relationship Study of a Potent α-Thrombin Binding Aptamer Incorporating Hexitol Nucleotides

The replacement of one or more nucleotide residues in the potent α-thrombin-binding aptamer NU172 with hexitol-based nucleotides has been devised to study the effect of these substitutions on the physicochemical and functional properties of the anticoagulant agent. The incorporation of single hexitol nucleotides at the T9 and G18 positions of NU172 substantially retained the physicochemical features of the parent oligonucleotide, as a result of the biomimetic properties of the hexitol backbone. Importantly, the NU172- T ^H9 mutant exhibited a higher binding affinity toward human α-thrombin than the native aptamer and an improved stability even after 24 h in 90 % human serum, with a significant increase in the estimated half-life. The anticoagulant activity of the modified oligonucleotide was also found to be slightly preferable to NU172. Overall, these results confirm the potential of hexitol nucleotides as biomimetic agents, while laying the foundations for the development of NU172-inspired α-thrombin-binding aptamers.     

3′-(1,2,3-Triazol-1-yl)-2′,3′-dideoxythymidine and 3′-(1,2,3-triazol-1-yl)-2′,3′-dideoxyuridine

Cycloaddition of different acetylenic compounds on the azido function of 3′-azido-2′,3′-dideoxythymidine and 3′-azido-2′,3′-dideoxyuridine afforded products with a 1,2,3-triazol-1-yl substituent in the 3′-position. In contrast with the parent compounds, these triazolyl derivatives had no appreciable activity against human immunodeficiency virus (HIV-1).