Photoleucine Survives Backbone Cleavage by Electron Transfer Dissociation. A Near-UV Photodissociation and Infrared Multiphoton Dissociation Action Spectroscopy Study

We report a combined experimental and computational study aimed at elucidating the structure of N-terminal fragment ions of the c type produced by electron transfer dissociation of photo-leucine (L*) peptide ions GL*GGKX. The c ₄ ion from GL*GGK is found to retain an intact diazirine ring that undergoes selective photodissociation at 355 nm, followed by backbone cleavage. Infrared multiphoton dissociation action spectra point to the absence in the c ₄ ion of a diazoalkane group that could be produced by thermal isomerization of vibrationally hot ions. The c ₄ ion from ETD of GL*GGK is assigned an amide structure by a close match of the IRMPD action spectrum and calculated IR absorption. The energetics and kinetics of c ₄ ion dissociations are discussed.

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Weak properties and robustness of t-Hill estimators

We describe a novel method of heavy tails estimation based on transformed score (t-score). Based on a new score moment method we derive the t-Hill estimator, which estimates the extreme value index of a distribution function with regularly varying tail. t-Hill estimator is distribution sensitive, thus it differs in e.g. Pareto and log-gamma case. Here, we study both forms of the estimator, i.e. t-Hill and t-lgHill. For both estimators we prove weak consistency in moving average settings as well as the asymptotic normality of t-lgHill estimator in iid setting. In cases of contamination with heavier tails than the tail of original sample, t-Hill outperforms several robust tail estimators, especially in small samples. A simulation study emphasizes the fact that the level of contamination is playing a crucial role. The larger the contamination, the better are the t-score moment estimates. The reason for this is the bounded t-score of heavy-tailed distributions (and, consequently, bounded influence functions of the estimators). We illustrate the developed methodology on a small sample data set of stake measurements from Guanaco glacier in Chile.     

Application of isothermal and isoperibolic calorimetry to assess the effect of zinc on cement hydration

The amount of zinc in the clinker or in the secondary raw materials has been increasing in recent years. Zinc can get to Portland cement from solid waste or tires which are widely used as a fuel for burning in a rotary kiln. The aim of this work was to determine the effect of zinc on Portland cement hydration. This effect was studied by isothermal and isoperibolic calorimetry. Both calorimetry methods are suitable for measurements during the first days of hydration. Isoperibolic calorimetry monitors hydration process in real-life conditions, while isothermal calorimetry does it at a defined chosen temperature. Zinc was added to the cement in the form of two soluble salts of Zn(NO₃)₂, ZnCl₂ and a poorly soluble compound ZnO. The concentration of zinc added was chosen as 0.05, 0.1, 0.5 and 1 mass%. The results show that increasing amounts of zinc ions in cement pastes lead to hydration retardation and reduce both the maximum temperature and the maximum heat flow due to the retarding effect of zinc. The newly formed compounds during hydration were identified by X-ray diffraction method.     

Manipulating Band Structure through Reconstruction of Binary Metal Sulfide for High‐Performance Thermoelectrics in Solution‐Synthesized Nanostructured Bi13S18I2

Reconstructing canonical binary compounds by inserting a third agent can significantly modify their electronic and phonon structures. Therefore, it has inspired the semiconductor communities in various fields. Introducing this paradigm will potentially revolutionize thermoelectrics as well. Using a solution synthesis, Bi₂S₃ was rebuilt by adding disordered Bi and weakly bonded I. These new structural motifs and the altered crystal symmetry induce prominent changes in electrical and thermal transport, resulting in a great enhancement of the figure of merit. The as‐obtained nanostructured Bi₁₃S₁₈I₂ is the first non‐toxic, cost‐efficient, and solution‐processable n‐type material with z T=1.0.     

Restrictions on classical distance-regular graphs

Let \(\varGamma \) be a distance-regular graph with diameter \(d \ge 2\). It is said to have classical parameters \((d, b, \alpha , \beta )\) when its intersection array \(\{b_0,b_1,\dots ,b_{d-1};c_1,c_2,\dots ,c_d\}\) satisfies

$$\begin{aligned} b_i= & {} ([d]_b - [i]_b)(\beta - \alpha [i]_b) \qquad \text {and} \qquad c_{i+1} = [i+1]_b (1 + \alpha [i]_b)\\&\quad (0 \le i \le d-1), \end{aligned}$$

where \([i]_b := 1 + b + \cdots + b^{i-1}\). Apart from the well-known families, there are many sets of classical parameters for which the existence of a corresponding graph is still open. It turns out that in most such cases we have either \(\alpha = b-1\) or \(\alpha = b\). For these two cases, we derive bounds on the parameter \(\beta \), which give us complete classifications when \(b = -2\). Distance-regular graphs with classical parameters are antipodal iff \(b=1\) and \(\beta =1+\alpha [d-1]_b\). If we drop the condition \(b=1\), it turns out that one obtains either bipartite or tight graphs. For the latter graphs, we find closed formulas for the parameters of the CAB partitions and the distance partition corresponding to an edge. Finally, we find a two-parameter family of feasible intersection arrays for tight distance-regular graphs with classical parameters \((d,b,b-1,b^{d-1})\) (primitive iff \(b \ne 1\)) and apply our results to show that it is realized only by d-cubes (\(b = 1\)).

     

DG method for the numerical pricing of two-asset European-style Asian options with fixed strike

The evaluation of option premium is a very delicate issue arising from the assumptions made under a financial market model, and pricing of a wide range of options is generally feasible only when numerical methods are involved. This paper is based on our recent research on numerical pricing of path-dependent multi-asset options and extends these results also to the case of Asian options with fixed strike. First, we recall the three-dimensional backward parabolic PDE describing the evolution of European-style Asian option contracts on two assets, whose payoff depends on the difference of the strike price and the average value of the basket of two underlying assets during the life of the option. Further, a suitable transformation of variables respecting this complex form of a payoff function reduces the problem to a two-dimensional equation belonging to the class of convection-diffusion problems and the discontinuous Galerkin (DG) method is applied to it in order to utilize its solving potentials. The whole procedure is accompanied with theoretical results and differences to the floating strike case are discussed. Finally, reference numerical experiments on real market data illustrate comprehensive empirical findings on Asian options.