Magnetic poly(glycidyl methacrylate) microspheres prepared by dispersion polymerization in the presence of electrostatically stabilized ferrofluids

Fine magnetite nanoparticles, both electrostatically stabilized and nonstabilized, were synthesized in situ by precipitation of Fe(II) and Fe(III) salts in alkaline medium. Magnetic poly(glycidyl methacrylate) (PGMA) microspheres with core‐shell structure, where Fe₃O₄ is the magnetic core and PGMA is the shell, were obtained by dispersion polymerization initiated with 2,2′‐azobisisobutyronitrile (AIBN), 4,4′‐azobis(4‐cyanovaleric acid) (ACVA), or ammonium persulfate (APS) in ethanol containing poly(vinylpyrrolidone) or ethylcellulose stabilizer in the presence of iron oxide ferrofluid. The average microsphere size ranged from 100 nm to 2 μm. The effects of the nature of ferrofluid, polymerization temperature, monomer, initiator, and stabilizer concentration on the PGMA particle size and polydispersity were studied. The particles contained 2–24 wt % of iron. AIBN produced larger microspheres than APS or ACVA. Polymers encapsulating electrostatically stabilized iron oxide particles contained lower amounts of oxirane groups compared with those obtained with untreated ferrofluid. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5827–5837, 2004     

Planar Chromatography of Some 1-Arylpiperazines Behaving as Dopaminergic Ligands

JPC – Journal of Planar Chromatography – Modern TLC - The chromatographic behavior of fourteen 1-arylpiperazine derivatives has been studied by thin-layer chromatography on both silica...     

Implementation of an integrated glucose POCT system

In response to a change of the Belgian National Directives whereby hospital laboratories became responsible for all point-of-care testing (POCT) performed within hospital walls a standardized and automated POC glucose-testing system was implemented in our hospital. The system consists of 50 AccuCheck Inform instruments (Roche Diagnostics, Vilvoorde, Belgium), 50 docking stations, a DataCare Server, and connections to the medical laboratory information system (MOLIS, Sysmex, Barchon, Belgium) and to the hospital information system. Implementation involved many parties and extensive preparation and communication. Key issues were bar-coded patient and user identification, training, and responsibilities. One year after the hospital wide implementation of this system the quality of POC glucose testing has significantly increased, thereby improving patient safety. This study describes a stepwise change over involving the medical laboratory and with a focus on hands-on quality.Presented at the ninth conference on Quality in the Spotlight, 18–19 March 2004, Antwerp, Belgium.     

Rheological and physical properties of aliphatic hyperbranched polyesters

The effects of the size (pseudo‐generation number) and nature of end groups on physical and rheological properties were investigated for a series of hyperbranched polyesters based on an ethoxylated pentaerythritol core and 2,2‐bis‐(hydroxymethyl)propionic acid repeat units. The observed linear dependence of the melt viscosity on the molar mass in the high pseudo‐generation‐number limit indicated that entanglement effects were substantially absent. Moreover, the marked influence of end capping of the end groups on the physical and rheological properties suggested that intermolecular interactions were dominated by contacts between the outer shells of the molecules, in which the end groups were assumed to be concentrated. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1218–1225, 2004     

Augmented Lagrangian Algorithms Based on the Spectral Projected Gradient Method for Solving Nonlinear Programming Problems

The spectral projected gradient method SPG is an algorithm for large-scale bound-constrained optimization introduced recently by Birgin, Martínez, and Raydan. It is based on the Raydan unconstrained generalization of the Barzilai-Borwein method for quadratics. The SPG algorithm turned out to be surprisingly effective for solving many large-scale minimization problems with box constraints. Therefore, it is natural to test its perfomance for solving the sub-problems that appear in nonlinear programming methods based on augmented Lagrangians. In this work, augmented Lagrangian methods which use SPG as the underlying convex-constraint solver are introduced (ALSPG) and the methods are tested in two sets of problems. First, a meaningful subset of large-scale nonlinearly constrained problems of the CUTE collection is solved and compared with the perfomance of LANCELOT. Second, a family of location problems in the minimax formulation is solved against the package FFSQP.     

Cotangent cohomology of Stanley-Reisner rings

Simplicial complexes X provide commutative rings A(X) via the Stanley- Reisner construction. We calculated the cotangent cohomology, i.e., T¹ and T² of A(X) in terms of X. These modules provide information about the deformation theory of the algebro geometric objects assigned to X.     

Harnack inequality for some classes of Markov processes

In this paper we establish a Harnack inequality for nonnegative harmonic functions of some classes of Markov processes with jumps. Mathematics Subject Classification (2000): Primary 60J45, 60J75, Secondary 60J25.This work was completed while the authors were in the Research in Pairs program at the Mathematisches Forschungsinstitut Oberwolfach. We thank the Institute for the hospitality.The research of this author is supported in part by NSF Grant DMS-9803240.The research of this author is supported in part by MZT grant 0037107 of the Republic of Croatia.     

Generating cryptographically strong Boolean functions using partial information

Periodica Mathematica Hungarica - In our paper we study the usage of partially defined Boolean functions (PDBFs) for generating cryptographically strong Boolean functions. A PDBF can be considered...     

Novel liquid crystals based on [1]benzothieno[3,2- b ][1]benzothiophene

Four series of new [1]benzothieno[3,2- b ][1]benzothiophene derivatives have been synthesized. In the non-chiral series a SmA phase occurs, while the chiral series exhibits a rather wide antiferroelectric SmC * A phase just below the SmA phase. The SmA-SmC * A phase transition has been studied using DSC and dielectric spectroscopy. In the SmC * A phase the spontaneous quantities have been measured. The tilt angle shows a typical temperature dependence and the values of spontaneous polarization are rather moderate. The length of the helical pitch increases on increasing the length of the non-chiral alkyl chain.