Polyhalogenoheterocyclic compounds: Part 51. [1] Macrocycles from 4-alkoxy-tetrafluoropyridine derivatives

4-Alkoxy-tetrafluoropyridine derivatives were used as building blocks for the synthesis of 14- and 16-membered macrocyclic ring systems comprising pyridine and either poly-ether or amine subunits; two of the macrocycles were characterised by X-ray crystallography.     

Tuning the magnetic properties of Zn1-xCoxO films

We compare the magnetic properties of two types of Co-doped ZnO films grown on sapphire with distinct structural quality. SQUID magnetometry as well as element-specific synchrotron studies reveal pure paramagnetic behavior for the samples with the highest structural quality, whereas samples with reduced structural quality exhibit superparamagnetic blocking behavior. In this sample signatures of phase separation are detected by X-ray diffraction and X-ray linear dichroism which accounts for the superparamagnetic blocking.     

In-depth study into the interaction of single walled carbon nanotubes with anthracene and p-terphenyl

Solubilization of single walled carbon nanotubes (SWNT) in the presence of polycyclic aromatic hydrocarbons (PAHs) such as p-terphenyl and anthracene has been shown. The suspensions formed are stable for periods greater than 48 months but to date experimental research is scarce regarding the interactions that are taking place. Spectroscopic analysis such as Raman and fluorescence are used to probe the interactions occurring between the PAHs and the SWNT over a wide concentration range. Previous studies show the fluorescence of the PAHs is quenched on interaction with SWNT and in the case of p-terphenyl, the spectrum is red shifted. This result prompted a study of a large range of concentrations to quantify the degree of interaction between the SWNT and PAHs. It was found at high concentrations that both the PAHs and SWNT formed aggregates and at lower concentrations it was found that free PAHs and isolated SWNT were interacting. The radial breathing modes (RBMs) in Raman spectroscopy gave detail as to how diameter selective the PAH samples are when compared to the pristine SWNT modes. An increase in the wavenumber of the RBMs for both composite spectra was observed and it is believed that such a result is due to the debundling of the SWNT on interaction with the PAHs. It was also found that anthracene and p-terphenyl selectively interact with SWNT and the selected SWNT were found to be within a distinct diameter range and possessed unique physical properties.     

Stratified waveguide grating coupler for normal fiber incidence

We propose a new stratified waveguide grating coupler (SWGC) to couple light from a fiber at normal incidence into a planar waveguide. SWGCs are designed to operate in the strong coupling regime without intermediate optics between the fiber and the waveguide. Two-dimensional finite-difference time-domain simulation in conjunction with microgenetic algorithm optimization shows that approximately 72% coupling efficiency is possible for fiber (core size of 8.3 microm and delta=0.36%) to slab waveguide (1.2-microm core and delta=3.1%) coupling. We show that the phase-matching and Bragg conditions are simultaneously satisfied through the fundamental leaky mode.     

Programming the Allocation of Funds Subject to Restrictions on Reported Results

A method is described of allocating funds between projects in a firm with the following characteristics: most investments are financed from internal sources; reasonable predictions can be made of investment opportunities arising several years ahead; management wishes to take account of the way the allocation will affect other published financial results besides cash flows. A numerical example shows how each allocation affects return on gross assets, current ratio and profit after tax in successive years. These measures are related in a linear programming formulation. The solution demonstrates how particular projects may attract funds by offering ways of altering published results. Related solutions show how the existence and timing of future opportunities affect the optimal current allocation and the value of the programme. Criteria are also developed for whether and when to borrow. It is shown that the returns to incremental borrowing may be much greater than the returns on any available investment considered in isolation, and may fall to zero although profitable single opportunities still exist.     

An Improved Synthesis of 5-Fluorothiophene-2-Carboxylic Acid

A new and efficient route to 5-fluorothiophene-2-carboxylic acid 1 was secured in two steps and 62% yield overall.     

Comparison of Proteins in Whole Blood and Dried Blood Spot Samples by LC/MS/MS

Dried blood spot (DBS) sampling methods are desirable for population-wide biomarker screening programs because of their ease of collection, transportation, and storage. Immunoassays are traditionally used to quantify endogenous proteins in these samples but require a separate assay for each protein. Recently, targeted mass spectrometry (MS) has been proposed for generating highly-multiplexed assays for biomarker proteins in DBS samples. In this work, we report the first comparison of proteins in whole blood and DBS samples using an untargeted MS approach. The average number of proteins identified in undepleted whole blood and DBS samples by liquid chromatography (LC)/MS/MS was 223 and 253, respectively. Protein identification repeatability was between 77 %–92 % within replicates and the majority of these repeated proteins (70 %) were observed in both sample formats. Proteins exclusively identified in the liquid or dried fluid spot format were unbiased based on their molecular weight, isoelectric point, aliphatic index, and grand average hydrophobicity. In addition, we extended this comparison to include proteins in matching plasma and serum samples with their dried fluid spot equivalents, dried plasma spot (DPS), and dried serum spot (DSS). This work begins to define the accessibility of endogenous proteins in dried fluid spot samples for analysis by MS and is useful in evaluating the scope of this new approach.

Iridium‐Catalyzed Reductive Nitro‐Mannich Cyclization

A new chemoselective reductive nitro‐Mannich cyclization reaction sequence of nitroalkyl‐tethered lactams has been developed. Relying on the rapid and chemoselective iridium(I)‐catalyzed reduction of lactams to the corresponding enamine, subsequent nitro‐Mannich cyclization of tethered nitroalkyl functionality provides direct access to important alkaloid natural‐product‐like structures in yields up to 81 % and in diastereoselectivities that are typically good to excellent. An in‐depth understanding of the reaction mechanism has been gained through NMR studies and characterization of reaction intermediates. The new methodology has been applied to the total synthesis of (±)‐epi‐epiquinamide in four steps.