Granulocyte-activating mediators (GRAM)

In the present study we investigated the capability of human epidermal cells to generate granulocyte-activating mediators (GRAM). It could be shown that human epidermal cells as well as an epidermoid carcinoma cell line (A431) produce an epidermal cell-derived granulocyte-activating mediator (EC-GRAM) which stimulates human granulocytes to release significant levels of toxic oxygen radicals as measured by a lucigenin-dependent chemiluminescence (CL). For further characterization of EC-GRAM the A431 cell line was used. Supernatants of A431 cells usually contained maximal EC-GRAM levels within 24 h of incubation. Factor production was enhanced by bacterial lipopolysaccharide (LPS), but not by silica particles and PHA. Moreover, freeze-thaw lysates of A431 cells and extracts of heat-separated human epidermis contained significant levels of EC-GRAM. Preincubation of granulocytes with EC-GRAM resulted in an enhanced response to subsequent stimulation with the chemotactic peptide f-met-phe. In contrast EC-GRAM did not affect the response to PMA or zymosan particles. However, EC-GRAM treated granulocytes were unresponsive to restimulation with EC-GRAM. Upon high performance liquid chromatography (HPLC) gel filtration EC-GRAM eluted within two major peaks exhibiting a molecular weight of 17 kD and 44 kD. According to its biochemical and biological properties EC-GRAM can be separated from other cytokines such as ETAF/-interleukin 1, interleukin 2, interferons, granulocyte colony-stimulating factor (G-CSF) and tumor necrosis factor (TNF). However, an antibody to human GM-CSF neutralized about 75% of the activity. These results indicate that EC-GRAM activity stimulating the generation of reactive oxygen species by granulocytes is probably due to GM-CSF

Spinodal phase separation in semi-interpenetrating polymer networks - polystyrene-cross-polymethacrylate

Morphology control in semi-interpenetrating polymer networks has been achieved by means of a two-step process, separating morphology formation and polymerization/crosslinking. Phase textures formed during spinodal liquid/liquid demixing of a solution of atactic polystyrene in methacrylate monomers were arrested by thermoreversible gelation of the polymer-rich phase as this phase passed its glass transition temperature. The phase separated structure was permanently stabilized by low-temperature crosslinking ultraviolet (UV) polymerization of the methacrylate monomer, and studied by transmission electron microscopy. Thus, it was directly observed how the initial demixing process depended on the initial viscosity of the polymer solution and the mode of quenching. Arrest of the earliest stage of spinodal demixing resulted in separated domains of 0.05-0.08 m thickness, which were separated by a distance of the spinodal wavelength . A cocontinuous network only developed in a relatively late stage of demixing

Intrazeolite phototopotaxy. EXAFS analysis of precursor 8{W(CO)6}-Na56Y and photooxidation products 16(WO3)-Na56Y and 28(WO3)-Na56Y

The intrazeolite photooxidation chemistry of alpha-cage encapsulated hexacarbonyltungsten(0) in Na56Y with O2, denoted n{W(CO)6}-Na56Y/O2/hv, which has previously been shown to provide a novel synthetic pathway to alpha-cage located tungsten(VI) oxide, denoted n(WO3)-Na56Y, is now the subject of an extended X-ray absorption fine structure (EXAFS) analysis. The EXAFS data of a precursor 8{W(CO)6}Na56Y, which contains on average one W(CO)6 per alpha-cage shows that the W(CO)6 guest maintains its structural integrity with only minor observable perturbations of the skeletal WC and ligand CO bonds compared to those found for the same molecule in the free state. The EXAFS analysis results for the photoxidation products 16(WO3)-Na56Y and 28(WO3)-Na56Y are very similar and display the presence of two terminal tungsten-oxygen bonds (1.75-1.77 angstrom) and two bridging tungsten-oxide bonds (1.94-1.95 angstrom), together with a short distance to a second tungsten (3.24-3.30 angstrom). This bond length and coordination number information for n = 16 and 28 samples is best interpreted in terms of the formation of a single kind of tungsten trioxide dimer unit (WO3)2, most likely interacting with extraframework Na+ cations, denoted ZONa...O2W(mu-O)2WO2...NaOZ. In conjunction with earlier chemical and spectroscopic information on this system, the EXAFS data support the contention that 16(WO3)-Na56Y contains a uniform array of single size and shape tungsten (VI) oxide dimers (WO3)2 housed in the 13-angstrom supercages of the zeolite Y host. The sequential addition of WO3 units to the 16(WO3)-Na56Y sample appears to increase the (WO3)2 dimer population, causing a buildup of alpha-cage encapsulated dimers-of-dimers {(WO3)2}2 rather than further cluster growth to trimers (WO3)2 and/or tetramers (WO3)4

Stabilization of colloidal palladium particles by a block copolymer of polystyrene and a block containing amide sidegroups

A block copolymer of polystyrene and poly(tert-butylmethacrylate) was prepared by anionic polymerization. The ester groups of the poly(tert-butylmethacrylate) were hydrolyzed, after wich the remaining carboxyl groups were reacted with pyrrolidine. The resulting block copolymer with amide sidegroups was used for stabilization of a palladium colloid in toluene

Correlations and enlarged superconducting phase of tt-J⊥J_\perp chains of ultracold molecules on optical lattices

We compute physical properties across the phase diagram of the $t$-$J_\perp$ chain with long-range dipolar interactions, which describe ultracold polar molecules on optical lattices. Our results obtained by the density-matrix renormalization group (DMRG) indicate that superconductivity is enhanced when the Ising component $J_z$ of the spin-spin interaction and the charge component $V$ are tuned to zero, and even further by the long-range dipolar interactions. At low densities, a substantially larger spin gap is obtained. We provide evidence that long-range interactions lead to algebraically decaying correlation functions despite the presence of a gap. Although this has recently been observed in other long-range interacting spin and fermion models, the correlations in our case have the peculiar property of having a small and continuously varying exponent. We construct simple analytic models and arguments to understand the most salient features.Comment: published version with minor modification

A scanning force microscopy study on the morphology of elastomer-coagent blends

Atomic force scanning microscopy (AFM) was used to investigate the dispersion of low molecular weight compounds in ethylene-propylene copolymers (EPM). Where other microscopical techniques failed to provide morphological details of this type of blend, as a result of the restricted resolution (light microscopy) or the volatility of the low molecular weight component (SEM), the AFM technique provided surface images, which show inclusions in the matrix of the uncrosslinked polymers