Synthesis and cyclo-oligomerization of 2-(bromomethyl)-3-aryl-2-propenoic acid derivatives

2-Bromomethyl-3-aryl-2-propenoic acids have been synthesized from Baylis-Hillman adducts derived from aromatic aldehydes and t-butyl acrylates as new precursors in MBH chemistry. Further triolides were synthesized by the cyclo-oligomerization of 2-bromomethyl-3-aryl-2-propenoic acids in the presence of Cs₂CO₃ demonstrating the synthetic utility of these motifs.     

Pyrolysis of poly(phenylene vinylene)s with polycaprolactone side chains

The thermal degradation characteristics of a new macromonomer poly(-caprolactone) with central 4,4′-dicarbaldehyde terphenyl moieties and poly(phenylene vinylene)s with well defined (-caprolactone), (PPV/PCL) as lateral substituents were investigated via direct pyrolysis mass spectrometry. The unexpectedly high thermal stability of the macromonomer was attributed to intermolecular acetylation of benzaldehyde yielding a hemiacetal and causing a crosslinked structure during the pyrolysis. Increased thermal stability of the PCL chains was detected for all samples. The increase in stability of PCL chains was much more pronounced than was detected for poly(p-phenylene)-graft-poly(-caprolactone) copolymer (PPP/PCL); the upward temperature shift was about 100 °C for PPV/PCL and only 20 °C for PPP/CL. This pronounced effect may be due to higher thermal stability of PPV compared to PPP and the decrease in steric hindrance for PPV with PCL side chains.     

Formation and shear-induced processing of quantum dot colloidal assemblies in a multiphase microfluidic chip

The controlled self-assembly of polymer-stabilized quantum dots (QDs) into mesoscale aqueous spherical assemblies termed quantum dot compound micelles (QDCMs) using a two-phase gas-segmented microfluidic reactor is described. Self-assembly is initiated by the fast mixing of water (approximately 1 s) with a blend solution of polystyrene-coated QDs and amphiphilic polystyrene-block-poly(acrylic acid) stabilizing chains via chaotic advection within liquid plugs moving through a sinusoidal channel. Subsequent recirculating flow within a post-formation channel subjects the dynamic QDCMs to shear-induced processing, controlled via the flow rate and channel length, before a final quench into pure water. During processing, larger QDCMs within the initial population undergo breakup into smaller particles, resulting in smaller mean particle sizes, smaller relative standard deviations, and more skewed distribution shapes, as the overall shear exposure is increased. For these cases, shear-induced size reduction is sufficient to dominate surface tension-driven growth.     

Reference intervals of serum folate and vitamin B12 developed from data of healthy subjects

 In this study the reference intervals for folate and vitamin B₁₂ were estimated according to the National Committee for Clinical Laboratory Standards Approved Guideline C28-A and International Federation of Clinical Chemistry recommendations. The study included 155 women and 124 men between ages 18–40. The health status was confirmed by history, physical examination and a questionnaire. The central 95% reference intervals of serum folate and vitamin B12 for women, determined non-parametrically, were found to be 3.9–18.1 ng/ml and 101–666.7 pg/ml, respectively. The reference values of serum folate and vitamin B12 for men were also found to be 2,5–17.6 ng/ml and 100–699.57 pg/ml, respectively. We did not observe subclass differences between females and males. Received: 15 April 2000 · Accepted: 15 April 2000     

Standardized method comparison for ACS:180 plus and Immulite sensitive PSA (sPSA) measurement methods

The aim of this study was to compare two immunoassay measurement methods, the ACS:180 Plus (Chiron Diagnostics) kit and the Immulite sPSA (DPC) kit. Method comparison analysis was performed according to EP9-A; approved guideline of NCCLS 51. Serum samples having a wide range of total prostate-specific antigen (PSA) concentrations were evaluated in split-sample analysis. F-test, t-test analysis and regression statistics were performed. In Deming regression analysis the coefficients were as follows; the slope=0.967; y-intercept=-0.148, r=0.989. An acceptable bias was seen since the systematical error was calculated to have a value less than the total allowable error calculated from biological variations. Non-parametric evaluation of the area under ROC curves for ACS:180 Plus and Immulite sPSA were 0.997 and 0.987, respectively. Diagnostic accuracy was at the level of p= 0.000 and no statistical difference was found between the two assay methods.     

Synthesis of new polyamidoximes and their crosslinking by transition metal ions

Three new polyamidoximes (PAO) having appropriate functionalities to bind transition metal ions were prepared. The polymers were obtained by the reaction of dichlorooximino ethane with the corresponding diamine. Characterization and crosslinking of PAOs via coordination with transition metal ions such as Ni(II), Co(II), Cu(II), and UO₂(II) are presented. The crosslinked polymer complexes exhibit good thermal stability. It was also found that both square planar and tetrahedral coordination structures are present in the crosslinked polymers.     

Cellulose‐Derived Functional Polyacetal by Cationic Ring‐Opening Polymerization of Levoglucosenyl Methyl Ether

The unsaturated bicyclic acetal levoglucosenyl methyl ether was readily obtained from sustainable feedstock (cellulose) and polymerized by cationic ring‐opening polymerization to produce a semicrystalline thermoplastic unsaturated polyacetal with relatively high apparent molar mass (up to ca. 36 kg mol^?1) and decent dispersity (ca. 1.4). The double bonds along the chain can undergo hydrogenation and thiol–ene reactions as well as crosslinking, thus making this polyacetal potentially interesting as a reactive functional material.     

In-plane and out-of-plane anisotropic magnetoresistances in La1 − x Pb x MnO3 thin films

The temperature and field dependences of in-plane (IP) and out-of-plane (OP) anisotropic magnetoresistances (AMRs) have been measured in La_{1 ? x} Pb _x MnO₃ (LPMO) thin films having different microstructures, namely the single-crystal (SC), nanocrystalline (NC) and polycrystalline (PC) microstructures. The OP AMR, irrespective of the microstructure, is found to be considerably larger than the IP AMR. The magnetization data show that the larger OP AMR arises because magnetization is favoured in the film plane owing to strain anisotropy. In addition, the temperature and field dependences of both IP and OP AMRs are governed by the crystallinity of the films, indicating that the AMRs are strongly influenced by the magnetization process.     

Effects of the bond dilution on the phase diagrams of a spin-1 transverse Ising model with crystal field interaction on a honeycomb lattice

A bond diluted spin-1 Ising model with crystal and transverse field interactions is examined for honeycomb lattice by introducing an effective field approximation that takes into account the correlations between different spins that emerge when expanding the identities. The effects of the crystal field as well as the transverse field and dilution on the phase diagrams and order parameter m_z are discussed in detail. A number of interesting and unusual phenomena such as reentrant phenomena and three successive phase transitions originating from the crystal field as well as the transverse field and bond dilution have been found.