Shuangancistrotectorines A–E,Dimeric Naphthylisoquinoline Alkaloids with Three Chiral Biaryl Axes from the Chinese Plant Ancistrocladus tectorius

Five novel dimeric naphthylisoquinoline alkaloids, shuangancistrotectorines A ( 3 a ), B ( 3 b ), C ( 4 ), D ( 5 a ), and E ( 5 b ), have been isolated from the twigs of the Chinese plant Ancistrocladus tectorius. Their absolute stereostructures were determined by spectroscopic and chiroptical methods in combination with quantum chemical CD calculations. In contrast to all other known dimeric naphthylisoquinoline alkaloids, in which the central binaphthalene axis is 6′,6′′‐coupled and thus not rotationally hindered, the dimers described here are linked via the sterically more hindered 3′,3′′‐ or 1′,1′′‐positions of the naphthalene units. They are thus the first such dimers—and even the very first natural products at all—that have three consecutive stereogenic axes. Hence, including the stereogenic centers, they have up to seven stereogenic units in total. Some of the compounds, in particular shuangancistrotectorines A, B, and D ( 3 a , 3 b , and 5 a ) exhibit very good, and specific, antiplasmodial activities.     

Sequencing and scheduling for filling lines in dairy production

We consider an integrated sequencing and scheduling problem arising at filling lines in dairy industry. Even when a processing sequence is decided, still a scheduling problem has to be solved for the sequence. This incorporates typical side constraints as they occur also in other sequencing problems in practice. Previously, we proposed a framework for general sequencing and scheduling problems: A genetic algorithm is utilized for the sequencing, incorporating a problem specific algorithm for the fixed-sequence scheduling. In this paper, we investigate how this approach performs for filling lines. Based on insights into structural properties of the problem, we propose different scheduling algorithms. In cooperation with Sachsenmilch GmbH, the algorithm was implemented for their bottleneck filling line, and evaluated in an extensive computational study. For the real data from production, our algorithm computes almost optimal solutions. However, as a surprising result, our simple greedy algorithms outperform the more elaborate ones in many aspects, showing interesting directions for future research.     

Effective mass anisotropy of hot electrons in nonparabolic conduction bands of n-doped InGaAs films using ultrafast terahertz pump-probe techniques

The anisotropic effective mass of energetic electrons in an isotropic, nonparabolic conduction band is revealed using ultrafast THz-pump-THz-probe techniques in a n-doped InGaAs semiconductor thin film. A microscopic theory is applied to identify the origin of the observed anisotropy and to show that the self-consistent light-matter coupling contributes significantly to the THz response.     

Hot-electron-driven enhancement of spin-lattice coupling in Gd and Tb 4f ferromagnets observed by femtosecond x-ray magnetic circular dichroism

Femtosecond x-ray magnetic circular dichroism was used to study the time-dependent magnetic moment of 4f electrons in the ferromagnets Gd and Tb, which are known for their different spin-lattice coupling. We observe a two-step demagnetization with an ultrafast demagnetization time of 750 fs identical for both systems and slower times which differ sizeably with 40 ps for Gd and 8 ps for Tb. We conclude that spin-lattice coupling in the electronically excited state is enhanced up to 50 times compared to equilibrium.     

Scheduling with few changes

In this work we consider scheduling problems where a sequence of assignments from products to machines – or from tasks to operators, or from workers to resources – has to be determined, with the goal of minimizing the costs (=money, manpower, and/or time) that are incurred by the interplay between those assignments. To account for the different practical requirements (e.g. few changes between different products/tasks on the same machine/operator, few production disruptions, or few changes of the same worker between different resources), we employ different objective functions that are all based on elementary combinatorial properties of the schedule matrix. We propose simple and efficient algorithms to solve the corresponding optimization problems, and provide hardness results where such algorithms most likely do not exist.     

A posteriori error estimation for arbitrary order FEM applied to singularly perturbed one-dimensional reaction-diffusion problems

FEM discretizations of arbitrary order r are considered for a singularly perturbed one-dimensional reaction-diffusion problem whose solution exhibits strong layers. A posteriori error bounds of interpolation type are derived in the maximum norm. An adaptive algorithm is devised to resolve the boundary layers. Numerical experiments complement our theoretical results.