A Practical Approach for Determining Rectangular Stock Sizes

In this paper we address the problem of determining what rectangular sizes should be stocked in order to satisfy a bill of materials composed of smaller rectangles. As is common in many manufacturing operations, the stock material will be cut using two-staged guillotine cutting patterns. We first generate a large number of stock sizes ideally suited to the bill of materials. Then we use a facility location algorithm to consolidate the stock sizes down to an acceptable number. Given the solution of what rectangular sizes to stock, a second program is used to map bills of materials into the stock rectangles. The effectiveness of our approach is demonstrated by generating stock sizes for a real-world bill of materials with 392 distinct order sizes and over 7700 order pieces.     

Spectrum line profiles: A generalized Voigt function including collisional narrowing

Reduction of collision-narrowed line profile functions to dimensionless form analogous to the standard form of the Voigt profile simplifies mathematical treatment. New quadratures are given which allow the efficient calculation of collision-narrowed profiles over the full physically realizable range of both collisional broadening and narrowing.     

Studies directed toward the preparation of polyene macrolide mimics

Cyclodimerization of two symmetrical but dissimilar fragments provides a facile route to macrocyclic dilactones containing conjugated polyolefins. Methods have been developed for the stereoselective synthesis of $\text{cis}$-2,4,6-triacetoxyheptanedial and the simple acylation of alcohols with dimethyl phosphonoacetic acid.     

Efforts toward expansion of the genetic alphabet: structure and replication of unnatural base pairs

Expansion of the genetic alphabet has been a long-time goal of chemical biology. A third DNA base pair that is stable and replicable would have a great number of practical applications and would also lay the foundation for a semisynthetic organism. We have reported that DNA base pairs formed between deoxyribonucleotides with large aromatic, predominantly hydrophobic nucleobase analogues, such as propynylisocarbostyril (dPICS), are stable and efficiently synthesized by DNA polymerases. However, once incorporated into the primer, these analogues inhibit continued primer elongation. More recently, we have found that DNA base pairs formed between nucleobase analogues that have minimal aromatic surface area in addition to little or no hydrogen-bonding potential, such as 3-fluorobenzene (d3FB), are synthesized and extended by DNA polymerases with greatly increased efficiency. Here we show that the rate of synthesis and extension of the self-pair formed between two d3FB analogues is sufficient for in vitro DNA replication. To better understand the origins of efficient replication, we examined the structure of DNA duplexes containing either the d3FB or dPICS self-pairs. We find that the large aromatic rings of dPICS pair in an intercalative manner within duplex DNA, while the d3FB nucleobases interact in an edge-on manner, much closer in structure to natural base pairs. We also synthesized duplexes containing the 5-methyl-substituted derivatives of d3FB (d5Me3FB) paired opposite d3FB or the unsubstituted analogue (dBEN). In all, the data suggest that the structure, electrostatics, and dynamics can all contribute to the extension of unnatural primer termini. The results also help explain the replication properties of many previously examined unnatural base pairs and should help design unnatural base pairs that are better replicated.     

Characterization of peptides from Aplysia using microbore liquid chromatography with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry guided purification

Liquid chromatography (LC) has been used extensively for the separation and isolation of peptides due to its high selectivity and peak capacity. An approach combining microbore LC with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-MS) detection is described to identify peptides in cells and guide the purification of peptides from the marine mollusc Aplysia californica. Direct MALDI-MS of neurons and processes provides molecular mass information for unknown peptides with almost no sample preparation, and LC-MALDI-MS allows the isolation and purification of these peptides from pooled samples, thus enabling new putative neuropeptides to be isolated from complex cellular samples. Both direct MALDI-MS and LC-MALDI-MS are compared in terms of detecting peptides from neuronal samples. Using both approaches, two peaks from Aplysia californica connectives having molecular masses of 5013 and 5021 have been isolated, partially sequenced and identified as novel collagen-like peptides.     

Extreme-ultraviolet metrology at SURF III

Inelastic X-ray scattering (IXS) is a general experimental technique for studying lattice and electronic excitations, which has undergone rapid development following the advent of the third generation synchrotron radiation facilities. X-ray Raman scattering (XRS) is inelastic scattering of X-rays due to the excitation associated with bound electrons in an atom. Its very small scattering cross-section is compensated for by a high-flux beam generated from a strong photon source. Instrumentation for IXS is now highly sophisticated, and has been applied to study a broad range of condensed matter systems [1 Schülke, e.g., W., ed. 2007. “We would like to limit our discussion to electronic excitations. For a comprehensive survey in the field, see”. In Electron Dynamics by Inelastic X-ray Scattering, New York: Oxford University Press.  [Google Scholar]].