Another look at complete positivity in generalized quantum dynamics: Reply to Raggio and Primas

In this rejoinder to a critique by Raggio and Primas of our paper, On Completely Positive Maps in Generalized Quantum Dynamics, we acknowledge that, contrary to our original assertion, the Bloch equations are indeed completely positive. We then explain briefly why this modification of our analysis does not alter its main conclusions.     

A comparative study on methods of optimal sample preparation for the analysis of oligonucleotides by matrix-assisted laser desorption/ionization mass spectrometry

Metal adducts (e.g., Na+ and K+) significantly hinder the analysis of oligonucleotides by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Although a number of sample purification methods exist, to date no comparative study exists to determine the most efficient method for purifying oligonucleotides. The objective of this work was to perform such a study. Several different oligonucleotide samples were synthesized. Aliquots of these samples were then purposely contaminated with sodium acetate to generate representative contaminated (salted) oligonucleotide samples. A number of popular oligonucleotide purification techniques were then tested as to their effectiveness at removing Na+ from the salted samples. The effectiveness of Na+ removal was qualitatively assessed by comparing the MALDI mass spectra of the original sample, the salted sample, and the salted sample after purification. Micropipet tips packed with C18 reversed-phase packing material (e.g., Zip Tips) appear to be the most effective means of purifying the oligonucleotides investigated. Minidialysis was found to be an effective alternative for purifying higher molecular weight oligonucleotides (> 10,000 u).     

The hall effect in some liquid alloys

The Hall coefficient has been measured for (a) liquid CuTe, AgTe and AuTe₂ and (b) liquid Cu-Sn alloy. The results are discussed in terms of the possible semiconducting nature of liquids comprising group (a) and in terms of bound state formation around the Sn atoms for those in group (b).     

Phase Transfer Catalysis Preparation of Acyl Isothiocyanates

The use of phase transfer catalysis, PTC, for nucleophillic substitution reactions is well documented.^1,2 Included among these reactions is the preparation of both alkyl³ and aryl⁴ thiocyanates. However, PTC reactions at an acyl carbon are much less common. Brándstróm⁵ has reported the preparation of acyl azides and Weber⁶ has used PTC to prepare benzoyl cyanide. Recently Illi⁷ has used PTC to acylate sterically crowded phenols.     

Synthesis of fused indolines by interrupted Fischer indolization in a microfluidic reactor

This study describes our development of a microfluidic reaction scheme for the synthesis of fused indoline ring systems found in several bioactive compounds. We have utilized a continuous-flow microfluidic reactor for the reaction of hydrazines with latent aldehydes through the interrupted Fischer indolization reaction to form fused indoline and azaindoline products. We have identified optimal conditions and evaluated the scope of this microfluidic reaction using various hydrazine and latent aldehyde surrogates. This green chemistry approach can be of general utility to rapidly produce indoline scaffolds and intermediates in a continuous manner.     

Phase Transfer Catalysis Preparation of Arvl,Thiocyanates

Phase transfer catalvsis, PTC, has become a common preparative method in organic chemistry. Numerous aliphatic substitution reactions have been performed yielding cvanides,¹ azides,² thiocyanates,³ ethers,⁴ and many other types of substitution products.¹     

Nanostructured Materials Synthesis in a Mixed Surfactant Mesophase

The mixed surfactant system of bis (2-ethylhexyl) sodium sulfosuccinate (AOT) and α-phosphatidylcholine (lecithin) forms a rigid gel-like mesophase in the presence of equal volumes of water and a hydrocarbon (isooctane). Small angle neutron scattering (SANS) results indicate that these structures undergo transitions from columnar hexagonal geometries to lamellar geometries depending on the water content and/or the temperature. The system is used to synthesize nanostructured ceramics (silica) in the aqueous microphase. Interpenetrating networks of poly-(hydroxyethylmethacrylate) and poly(styrene) are also synthesized using the aqueous microphase to support the water soluble monomer (hydroxyethyl methacrylate) and the organic microphase (styrene). SANS results indicate that the template structure is maintained during materials synthesis.