Complexity Results and Exact Algorithms for Robust Knapsack Problems

This paper studies the robust knapsack problem, for which solutions are, up to a certain point, immune from data uncertainty. We complement the works found in the literature, where uncertainty affects only the profits or only the weights of the items, by studying the complexity and approximation of the general setting with uncertainty regarding both the profits and the weights, for three different objective functions. Furthermore, we develop a scenario-relaxation algorithm for solving the general problem and present computational results.     

Do Sulfonamides Interact with Aromatic Rings?

Aromatic rings form energetically favorable interactions with many polar groups in chemical and biological systems. Recent molecular studies have shown that sulfonamides can chelate metal ions and form hydrogen bonds, however, it is presently not established whether the polar sulfonamide functionality also interacts with aromatic rings. Here, synthetic, spectroscopic, structural, and quantum chemical analyses on 2,6-diarylbenzenesulfonamides are reported, in which two flanking aromatic rings are positioned close to the central sulfonamide moiety. Fine-tuning the aromatic character by substituents on the flanking rings leads to linear trends in acidity and proton affinity of sulfonamides. This physical-organic chemistry study demonstrates that aromatic rings have a capacity to stabilize sulfonamides via through-space NH–π interactions. These results have implications in rational drug design targeting electron-rich aromatic rings in proteins.     

Single-pass and approximate dynamic-programming algorithms for order acceptance and capacity planning

This paper investigates dynamic order acceptance and capacity planning under limited regular and non-regular resources. Our goal is to maximize the profits of the accepted projects within a finite planning horizon. The way in which the projects are planned affects their payout time and, as a consequence, the reinvestment revenues as well as the available capacity for future arriving projects. In general, project proposals arise dynamically to the organization, and their actual characteristics are only revealed upon arrival. Dynamic solution approaches are therefore most likely to obtain good results. Although the problem can theoretically be solved to optimality as a stochastic dynamic program, real-life problem instances are too difficult to be solved exactly within a reasonable amount of time. Efficient and effective heuristics are thus required that supply a response without delay. For this reason, this paper considers both ‘single-pass’ algorithms as well as approximate dynamic-programming algorithms and investigates their suitability to solve the problem. Simulation experiments compare the performance of our procedures to a first-come, first-served policy that is commonly used in practice.     

Formation and photoinduced processes of a self-assembled subphthalocyanine-porphyrin-phthalocyanine supramolecular complex

We report herein the formation and excitation energy transfer property of a ternary supramolecular complex of subphthalocyanine-porphyrin-phthalocyanine held by host-guest interactions.     

Grain-boundary fluctuations in two-dimensional colloidal crystals

We study grain-boundary fluctuations in two-dimensional colloidal crystals in real space and time using video microscopy. The experimentally obtained static and dynamic correlation functions are very well described by expressions obtained using capillary wave theory. This directly leads to values for the interfacial stiffness and the interface mobility, the key parameters in curvature-driven grain-boundary migration. Furthermore, we show that the average grain-boundary position exhibits a one-dimensional random walk as recently suggested by computer simulations [Z. T. Trautt, M. Upmanyu, and A. Karma, Science 314, 632 (2006)]. The interface mobility determined from the mean-square displacement of the average grain-boundary position is in good agreement with values inferred from grain-boundary fluctuations.     

Ultra-low-angle microtomy and static secondary ion mass spectrometry for molecular depth profiling of UV-curable acrylate multilayers at the nanoscale

Development of sustainable materials requires methods capable of probing the molecular composition of samples not only at the surface but also in depth. Static secondary ion mass spectrometry (S-SIMS) characterises the distribution of organic and inorganic compounds at the surface. Ultra-low-angle microtomy (ULAM) has been studied as an alternative or complementing method to the molecular depth profiling with, e.g. C₆₀⁺ projectiles. Acrylate-based multilayers relevant to industrial inkjet printing have been sectioned at a cutting angle below 1°. In this way, analysis of the section over a distance of 1 μm allows a depth range in the order of a few nm in the original sample to be achieved. Adequate procedures to optimise the ULAM step and minimise or control the cutting artefacts have been developed. The combination of ULAM with S-SIMS has allowed a depth resolution of 10 nm to be obtained for components at a distance of 35 μm from the surface.     

Synthesis of 4,6‐Dimethyldibenzothiophene and 1,2,3,4‐Tetrahydro‐4,6‐dimethyldibenzothiophene via Tilak Annulation

1,2,3,4‐Tetrahydro‐4,6‐dimethyldibenzothiophene was prepared by coupling 2‐bromo‐3‐methylcyclohexanone with 2‐methylbenzenethiol and annulating the product with the aid of polyphosphoric acid. A mixture of 1,2,3,4‐tetrahydro‐4,6‐dimethyldibenzothiophene and 4,6‐dimethyldibenzothiophene was prepared by coupling 2‐bromo‐3‐methylcyclohex‐2‐en‐1‐one with 2‐methylbenzenethiol and annulating the product with the aid of polyphosphoric acid. 2‐Bromo‐3‐methylcyclohexanone was synthesized by conjugate addition of Me₃Al to 2‐bromocyclohex‐2‐en‐1‐one with CuBr as catalyst and 2‐bromo‐3‐methylcyclohex‐2‐en‐1‐one by bromination? elimination of 3‐methylcyclohex‐2‐en‐1‐one. 1,2,3,4,4a,9b‐Hexahydro‐4,6‐dimethyldibenzothiophene was prepared by reduction of 1,2,3,4‐tetrahydro‐4,6‐dimethyldibenzothiophene with Zn and CF₃COOH.