Protein‐like structure and activity in synthetic polymers

The structure and activity of proteins is the gold standard for functional polymeric materials. This highlight seeks to calibrate the reader with respect to recent attempts to mimic the various structural and functional traits of proteins using the techniques of modern polymer chemistry. From advances in sequence‐controlled polymers (primary structure), to peptidomimetics, foldamers, single‐chain nanoparticles (secondary and tertiary structure), accessing the various structural aspects of protein chemistry is a vibrant research area. Likewise, the properties and utility of proteins in applications such as catalysis and molecular recognition are being emulated in the laboratory to great effect. Rather than provide an exhaustive review on any one of these topics, this article seeks to highlight the common thread among them, encouraging discussion and collaboration that will result in the next generation of smart materials with advanced structure and function. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 191–206     

Infrared and Raman spectroscopy at high pressures

Pressure is accepted theoretically as a useful variable. However in a studies on liquid or solid samples, it is still relatively unusual for pressure to be used as an experimental variable. The reluctance of experimentalists to use this theoretically attractive variable is caused mainly by the technical difficulties associated with the use of sufficiently high pressures. In this talk I will try to show that in many cases the experimental limitations are no longer those introduced by the use of high pressures. High pressure spectroscopic studies clearly imply the use of high pressure spectroscopic cells. A brief account will therefore be given of the various types of high pressure optical cells which are currently being used for spectroscopic studies. Each individual high pressure spectroscopic study has its own special justification. However there are a few quite general observations that can be made which cover many of the specific objectives of individual high pressure spectroscopic studies. For example:(i) pressure induced frequency shifts carry unambiguous information about anharmonic terms in the relevant potential function (i.e. the potential V is a function of distance d. therefore pressure can be used to change d and study V.)(ii) all known materials undergo structural phase transitions if the form which is thermodynamically stable under ambient conditions is compressed to high enough pressures: these high pressure phases should be studied.(iii) as the application of pressure forces a material towards a phase transition, the spectroscopic study can be used to gain information about the approaching structural instability.(iv) virtually all infrared and Raman spectra contain examples of Fermi resonance which confuse the interpretation of the spectra and the effects of pressure are valuable aids to the correct assignment of the resonating levels.(v) pressure induced frequency shifts can often give extra information to help with the more reliable assignment of features within a spectrum.The above points will be discussed and illustrated by examples chosen mainly from recent work by members of the spectroscopy group at King's College London.     

Study of π−π− correlations in the reaction pp → π−π−+ anything at 28.5 GeV/c

Correlations between π^?π^? pairs are studied in the reaction pp → π^?π^?+ anything at 28.5 GeV/c. We find that if we examine the data for each multiplicity separately, the major portion of the data (90%) shows no significant two-particle correlations.     

The enumeration of bipartite graphs

The standard construction of graphs with n connected components is modified here for bicolored graphs by letting S_n × H act on the function space $\text{Y}{}^1\text{where}\text{X={1,2,…,n}, Y}$ is the set of connected bicolored graphs, and H is the group that interchanges the vertex colors. Then DeBruijn's Generalization of Polya's Theorem is applied to arrive at a direct algebraic relationship between the generating functions for bicolored and connected bicolored graphs. As the former generating function is easily computable, this relationship gives us the latter generating function which is precisely the generating function for connected bipartite graphs.     

Current and target jets produced in high energy neutrino-deuterium interactions

In an analysis of ≈ 7000 charged current events produced in high energy neutrino-deuterium interactions, we observe that the struck quark jet has a wider spread in P_t than that from the recoiling diquark jet for events with hadronic energy W > 9 GeV. This suggests that the effect signals the onset of gluon emission from the single quark.     

Human Enzymes for Organic Synthesis

Human enzymes have been widely studied in various disciplines. The number of reactions taking place in the human body is vast, and so is the number of potential catalysts for synthesis. Herein, we focus on the application of human enzymes that catalyze chemical reactions in course of the metabolism of drugs and xenobiotics. Some of these reactions have been explored on the preparative scale. The major field of application of human enzymes is currently drug development, where they are applied for the synthesis of drug metabolites.     

The chromatic polynomial of an unlabeled graph

We investigate the chromatic polynomial χ(G, λ) of an unlabeled graph G. It is shown that $\text{χ(G, λ) = (}\text{1}\text{|A(g)|}\text{) Σ}{}_{\mathrm{\pi \; \in \; A(g)}}\text{χ(g, π, λ)}$, where g is any labeled version of G, A(g) is the automorphism group of g and χ(g, π, λ) is the chromatic polynomial for colorings of g fixed by π. The above expression shows that χ(G, λ) is a rational polynomial of degree n = |V(G)| with leading coefficient $\text{1}\text{|A(g)|}$. Though χ(G, λ) does not satisfy chromatic reduction, each polynomial χ(g, π, λ) does, thus yielding a simple method for computing χ(G, λ). We also show that the number N(G) of acyclic orientations of G is related to the argument λ = ?1 by the formula $\text{N(G) = (}\text{1}\text{|A(g)|}\text{) Σ}{}_{\mathrm{\pi \; \in \; A(g)}}\text{(?1)}{}^{\mathrm{s(\pi )}}\text{χ(g, π, ?1)}$, where s(π) is the number of cycles of π. This information is used to derive Robinson's (“Combinatorial Mathematics V” (Proc. 5th Austral. Conf. 1976), Lecture Notes in Math. Vol. 622, pp. 28–43, Springer-Verlag, New York/Berlin, 1977) cycle index sum equations for counting unlabeled acyclic digraphs.