Magnetic field alignment of rod-coil block copolymers is shown to proceed through coupling to the diamagnetic moment of individual rod blocks. Block copolymer self-assembly then leads to alignment of the interfaces perpendicular to the field lines and long range order on a 10 nm lengthscale. This is in contrast to previously demonstrated alignment techniques, which couple to the block copolymer interfaces rather than individual molecules. Furthermore, alignment occurs without direct physical contact to samples millimeters in size.

The ability to strongly and sequence-specifically attach modifications such as fluorophores and haptens to individual double-stranded (ds) DNA molecules is critical to a variety of single-molecule experiments. We propose using modified peptide nucleic acids (PNAs) for this purpose and implement them in two model single-molecule experiments where individual DNA molecules are manipulated via microfluidic flow and optical tweezers, respectively. We demonstrate that PNAs are versatile and robust sequence-specific tethers.

This review is a practical guide for experimentalists interested in specifically labeling internal sequences on double-stranded (ds) DNA molecules for single-molecule experiments. We describe six labeling approaches demonstrated in a single-molecule context and discuss the merits and drawbacks of each approach with particular attention to the amount of specialized training and reagents required. By evaluating each approach according to criteria relevant to single-molecule experiments, including labeling yield and compatibility with cofactors such as Mg2+, we provide a simple reference for selecting a labeling method for given experimental constraints. Intended for non-specialists seeking accessible solutions to DNA labeling challenges, the approaches outlined emphasize simplicity, robustness, suitability for use by non-biologists, and utility in diverse single-molecule experiments.

The physical properties of bitumen (i.e., asphalt) are a topic of consistent interest in the fields of oil, gas, and mining. In this study, the relationship between bitumen viscosity and the rotation of asphaltene clusters was empirically explored via broadband dielectric spectroscopy (BDS). Cluster size was found to be independent of the concentration, and BDS was found to be a reliable means to predict viscosity in neat bitumen and concentrated solutions. Because of the simplicity and portability of modern impedance analyzers, this technique offers a unique method for estimating a wide range of oil viscosities in the field (from <101 to >105 cP) and even offers the possibility of in situ oil viscosity monitoring in pipelines or oil-lubricated mechanical systems.