2‐Aminopyrimidine–3,3,3‐triphenylpropanoic acid (1/1)

The title bimolecular compound, C₄H₅N₃·C₂₁H₁₈O₂, constructed from 2‐aminopyrimidine and 3,3,3‐triphenylpropanoic acid, forms a tetramolecular hydrogen‐bonded motif via O—H...N, N—H...O and N—H...N contacts. This aggregate organizes to give crystal‐packing motifs with hydrophilic and hydrophobic regions.     

Optimal control methods applied on the ionization processes of alkali dimers

We present two novel optimization methods by employing shaped fs-laser pulses in a closed feedback loop. The first describes control pulse cleaning where extraneous features were removed by applying genetic pressure on certain pulse components. The second reports parametric optimization with intuitive parameters such as subpulse distances, chirps, phase differences, and spectral peak patterns. These methods were conducted on the ionization process of alkali dimers produced in a molecular beam and improved the performances of the optimized pulses compared with short pulses at the same pulse energy. Moreover, we attempt to analyze the obtained pulse shapes regarding the underlying optimized processes. Further investigations concerning isotope selective fragmentation and optimal control of excitation processes of ultracold rubidium dimers in a magneto-optical trap (MOT) are also shown.     

Higher Sucrose Analogs: Homologation of a Glucose Unit of Sucrose by Two Carbon Atoms

Abstract

The primary hydroxyl groups (at C-6 and C-6′) in 2,3,4,3′4′-penta-O-benzyl-l′-O-methoxymethyl sucrose (2) can be reactively differentiated with tert-butyldiphenylsilyl chloride. Reaction of 2 with TBDPSCl afforded only one monosilylated product protected at C-6′ (6). The regioisomeric monoprotected sucrose 8 was prepared by selective deprotection of the double silylated derivative 7. Compound 6 was converted into 2,3,4,3′,4′-penta-O-benzyl-6-carbomethoxymethylidene-1′-O-methoxymethylsucrose 10 in three steps. Osmylation of the double bond in 10 afforded stereoisomeric homologated sucroses: 11a [6(S),7(R)] and 11b [6(R),7(S)] in the ratio 3:2. A large downfield shift of the H-1 (up to 0.5 ppm) was observed for 6′-silylated derivatives.     

Synthesis and Structural Analysis of Higher Analogs of Sucrose

ABSTRACT

Three sucrose monoalcohols with free hydroxyl groups at C-1', C-6, and C-6' (1, 4, and 6) were prepared selectively and in good yield from 2,3,3',4,4'-penta-O-benzylsucrose. These compounds were oxidized to aldehydes and reacted with stabilized ylide, Ph₃P=CHCO₂Me to afford appropriate α,β-unsaturated esters 10, 11, and 12. Each olefin was cis-hydroxylated with OsO₄/NMO to stereoisomeric diols 13/14, 15/16, and 17/18, configurations of which were assigned by chemical correlation and CD evaluation. Stereoselectivity of the osmylation reaction was surprisingly low (ca 3:2), especially as compared to a similar process performed on simple derivatives of 6,7-unsaturated methyl glycosides for which the ratio of isomeric diols was assigned as 10:1. The osmylation of 11 (derivative homologated by a C₂-unit at the glucose part) did not obey Kishi's rule. Horner-Emmons reaction of sucrose aldehyde 7 with a sugar-derived phosphonate 22 afforded α,β-unsaturated derivative 24, homologated by a C₇-unit at the glucose end.     

Using invariants to determine change detection in dynamical system with chaos

The problem of change detection in dynamical systems originated from ordinary differential equations and real world phenomena is covered. Until now suitable methods for detecting changes for linear systems and nonlinear systems have been elaborated but there are no such method for chaotic systems. In this paper we propose the method of change detection based on the fractal dimension, which is the one of characteristics dynamical system invariants. The application of the method is illustrated with simulations.     

Exact Pollard-like internal water waves

In this paper we construct a new solution which represents Pollard-like three-dimensional nonlinear geophysical internal water waves. The Pollard-like solution includes the effects of the rotation of Earth and describes the internal water wave which exists at all latitudes across Earth and propagates above the thermocline. The solution is provided in Lagrangian coordinates. In the process we derive the appropriate dispersion relation for the internal water waves in a stable stratification and discuss the particles paths. An analysis of the dispersion relation for the constructed model identifies one mode of the internal water waves.     

Influence of superabsorbent polymers on hydration of cement pastes with low water-to-binder ratio

Internal curing with superabsorbent polymers (SAP) is a method for promoting hydration of cement and limiting self-desiccation, shrinkage and cracking in high-performance, and ultra high-performance concrete with low water-to-binder ratio. SAP are introduced in the dry state during mixing and form water-filled inclusions by absorbing pore solution. The absorbed solution is later released to the cement paste during hydration of the cement. In this paper, cement pastes with low water-to-binder ratios incorporating superplasticizer and different dosages of SAP and corresponding additional water were prepared. Reference cement pastes without SAP but with the same amount of water and superplasticizer were also mixed. Isothermal calorimetry was used to measure hydration heat flow. Water entrainment by means of SAP increased the degree of hydration at later hydration times in a manner similar to increasing the water-to-binder ratio. Addition of SAP also delayed the main calorimetric hydration peak compared to the reference pastes, however, in a less prominent manner than the increase in water-to-cement ratio.     

On the graph labellings arising from phylogenetics

We study semigroups of labellings associated to a graph. These generalise the Jukes-Cantor model and phylogenetic toric varieties defined in [Buczynska W., Phylogenetic toric varieties on graphs, J. Algebraic Combin., 2012, 35(3), 421–460]. Our main theorem bounds the degree of the generators of the semigroup by g + 1 when the graph has first Betti number g. Also, we provide a series of examples where the bound is sharp.