A structure preserving approach to the simulation of non-smooth dynamics

The investigated multibody dynamics involve perfectly elastic, partially elastic and perfectly plastic contacts and a structure preserving approach is used in forward dynamics and optimal control simulations. The applied mechanical integrator is based on a constrained version of the Lagrange-d’Alembert principle and it represents exactly the behaviour of the analytical solution concerning the consistency of momentum maps and symplecticity: it is called symplectic momentum scheme. To guarantee the geometric exactness during the establishing or releasing of contacts, the non-smooth problem is solved including the computation of the contact configuration, time and force, instead of relying on a smooth approximation of the contact problem via a penalty potential. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Flows over time in time-varying networks: Optimality conditions and strong duality

There has been much research on network flows over time due to their important role in real world applications. This has led to many results, but the more challenging continuous time model still lacks some of the key concepts and techniques that are the cornerstones of static network flows. The aim of this paper is to advance the state of the art for dynamic network flows by developing the continuous time analogues of the theory for static network flows. Specifically, we make use of ideas from the static case to establish a reduced cost optimality condition, a negative cycle optimality condition, and a strong duality result for a very general class of network flows over time.     

On the spectral density function of the Laplacian of a graph

Let X$X$ be a finite graph. Let |V|$\left|V\right|$ be the number of its vertices and d$d$ be its degree. Denote by _F1(X)$F_1\left(X\right)$ its first spectral density function which counts the number of eigenvalues ≤λ²$\le {\lambda }^2$ of the associated Laplace operator. We provide an elementary proof for the estimate _F1(X)(λ)−_F1(X)(0)≤2⋅(|V|−1)⋅d⋅λ$F_1\left(X\right)\left(\lambda \right)-F_1\left(X\right)\left(0\right)\le 2\cdot (\left|V\right|-1)\cdot d\cdot \lambda$ for 0≤λ<1$0\le \lambda <1$ which has already been proved by Friedman (1996) [3] before. We explain how this gives evidence for conjectures about approximating Fuglede–Kadison determinants and L²$L^2$-torsion.     

Maximal Plurifinely Plurisubharmonic Functions

The main purpose of this paper is to introduce and study the notion of -maximal \(\mathcal {F}\) -plurisubharmonic functions, which extends the notion of maximal plurisubharmonic functions on a Euclidean domain to an -domain of ? ⁿ in a natural way. Our main result is that a finite -plurisubharmonic function u on a plurifine domain U satisfies (d d ^c u) ⁿ = 0 if and only if u is -locally -maximal outside some pluripolar set. In particular, a finite -maximal plurisubharmonic function u satisfies (d d ^c u) ⁿ = 0.     

Simultaneous Determination of 12 Sulfonylurea Herbicides in Drinking Water after SPE by LC-DAD

A liquid chromatographic method (LC) with diode array detection (DAD) for the routine screening and quantification of highly applicated polar herbicides in drinking water samples was developed. The investigated herbicides consisted of 12 sulfonylurea herbicides (amidosulfuron, flazasulfuron, foramsulfuron, iodosulfuron-methyl Na, mesosulfuron-methyl, metsulfuron-methyl, nicosulfuron, prosulfuron, thifensulfuron-methyl, triasulfuron and tritosulfuron) together with 6 polar pesticides of relevance (atrazine, desethylatrazine, desisopropylatrazine, chlortoluron, diuron, fluoxypyr). The herbicides were extracted and concentrated by off-line solid-phase extraction and subsequently eluates were analyzed by LC-DAD. Recoveries obtained from fortified water samples at 100 ng L^?1 were in the range of 84–107% with RSD’s <20%. The limit of detection varied from 2 to 16 ng L^?1.     

Setup for evaluation of fatigue crack growth in rubber: Pure shear sample geometries tested in tension-compression mode

A novel measurement setup is developed to determine fatigue crack growth and heat build-up in rubber. Loading conditions include tensile and compressional loads. Deviations in the crack shape are detected with special features (swivel arm and additional light sources) and provide the possibility of a subsequent manual correction of the shadow crack length. This results in improved reproducibility and a worst-case scenario is obtained.     

Efficiency of Different Methods and Solvents for the Extraction of Polycyclic Aromatic Hydrocarbons from Soils

The efficiencies of supercritical fluid extraction (SFE), accelerated solvent extraction (ASE), Soxhlet, and ultrasonic extraction in the analysis of polycyclic aromatic hydrocarbons (PAHs) in soils were evaluated. Solvents with different polarity were used to extract the PAHs from two soils, one with high and one with low contamination level. ASE showed good results with all solvents almost independent of the solvent polarity and the best results with acetone-toluene (1 : 1). Ultrasonic extraction with acetone-toluene for the uncontaminated soil and acetone-ethanolamine for the highly contaminated also showed good recoveries. The time-consuming Soxhlet extraction with pentane or dichloromethane was less effective. The PAH recovery from SFE was related to the soil matrix or the contamination level. The best extraction conditions (CO 2 /10% pentane) are successful for the soil with a low contamination level and a high humic acid content whereas the extractions of the highly contaminated soil gave poor results irrespective of the solvent used.     

Synthesis of a Novel Series of (E,E)-4,6-bis(styryl)-2-O-Glucopyranosyl-Pyrimidines and Their Potent Multidrug Resistance (MDR) Reversal Activity Against Cancer Cells

A novel series of methoxy or benzyloxy substituted (E,E)-4,6-bis(styryl)-2-O-glucopyranosyl-pyrimidines as curcuminoid analogs were synthesized in four steps with total yields of 21.5% to 33.9%. A549 and HL60 cells were employed for the anticancer activity testing. The results demonstrated that 5a, 5c, and 5e have some inhibitory activity against the HL-60 cell line. Unfortunately, no compound displayed inhibitory activity against A549 except for 5c. MDR reversal activity results demonstrated that compounds 4a (RF = 12.3) and 4b (RF = 18.5) showed strong reversal activity to the P-gp-mediated LCC6MDR cells compared to verapamil (RF = 3.2) and no cytotoxicity to cancer or normal cell lines even at a high concentrations (100 μM).     

C‐Glycosyl Amino Acids through Hydroboration–Cross‐Coupling of exo‐Glycals and Their Application in Automated Solid‐Phase Synthesis

O‐Glycosylation is one of the most important post‐translational modifications of proteins. The attachment of carbohydrates to the peptide backbone influences the conformation as well as the solubility of the conjugates and can even be essential for binding to specific ligands in cell–cell interactions or for active transport over membranes. This makes glycopeptides an interesting class of compounds for medical applications. To enhance the long‐term availability of these molecules in vivo, the stabilization of the glycosidic bond between the amino acid residue and the carbohydrate is of interest. The described modular approach affords β‐linked C‐glycosyl amino acids by a sequence of Petasis olefination of glyconolactones, stereoselective hydroboration and a mild B‐alkyl‐Suzuki coupling reaction. The coupling products were transformed to C‐glycosyl amino acid building‐blocks suitable for solid‐phase synthesis and successfully incorporated into a partial sequence of the tumor‐associated MUC1‐glycopeptide. The resulting C‐glycopeptides are candidates for the development of long‐term stable mimics of O‐glycopeptide vaccines.     

(Hexafluorosilicato‐κ2F,F′)bis(1,10‐phenanthroline‐κ2N,N′)zinc(II) methanol monosolvate

The title compound, [Zn(SiF₆)(C₁₂H₈N₂)₂]·CH₃OH, contains a neutral heteroleptic tris‐chelate Zn^II complex, viz. [Zn(SiF₆)(phen)₂] (phen is 1,10‐phenanthroline), exhibiting approximate molecular C₂ point‐group symmetry. The Zn^II cation adopts a severely distorted octahedral coordination. As far as can be ascertained, the title complex represents the first structurally characterized example of a Zn^II complex bearing a bidentate‐bound hexafluorosilicate ligand. A density functional theory study of the isolated [Zn(SiF₆)(phen)₂] complex was undertaken to reveal the influence of crystal packing on the molecular structure of the complex. In the crystal structure, the methanol solvent molecule forms a hydrogen bond to one F atom of the hexafluorosilicate ligand. The hydrogen‐bonded assemblies so formed are tightly packed in the crystal, as indicated by a high packing coefficient (74.1%).