Primer-induced labeling of pea and field bean chromosomes in situ and in suspension

A protocol for primed in situ DNA labeling (PRINS) was optimized for pea (Pisum sativum L.) and field bean (Vicia faba L.) chromosomes attached to coverslips. Cloned DNA or synthetic oligonucleotides were used as probes for repetitive DNA sequences (rDNA, Fok-element) and different reaction conditions were tested to achieve the highest specific signal-to-background ratio. A procedure based on direct labeling by fluorescein-dUTP was compared with an indirect one using digoxigenin detected by fluorescently labeled antibody. Under optimal conditions, strong and specific signals were obtained exclusively on chromosome regions known to contain respective DNA sequences. Compared to the direct labeling, significantly stronger signals were obtained when the indirect procedure was used. Both types of labeling were successfully applied to chromosomes in suspension and were shown to produce signals comparable to that obtained with chromosomes attached to coverslips. It is expected that primed in situ DNA labeling en suspension (PRINSES) will provide a basis for flow-cytometric discrimination and sorting of otherwise indistinguishable chromosomes according to their specific fluorescent labeling.     

Temperature and modulation characteristics of resonant-cavitylight-emitting diodes

Resonant-cavity light-emitting diodes (RCLED) are novel, high-efficiency light-emitting diodes which employ optical microcavities. These diodes have higher intensities and higher spectral purity as compared to conventional LEDs. Analytical formulas are derived for the enhancement of the spontaneous emission along the optical axis of the cavity. The design rules for high-efficiency operation of RCLEDs are established. The temperature dependence of the emission intensity is analyzed in the range 20-80° and it is described by an exponential dependence with a characteristic temperature of 112 K. The modulation characteristics of RCLEDs exhibit 3 dB frequencies of 580 MHz. Eye diagrams at transmission rates of 622 Mb/s are wide open indicating the suitability of RCLEDs for high-speed data transmission     

Protein adsorption onto poly(ether urethane ureas) containing Methacrol 2138F: a surface-active amphiphilic additive

Surface characterization and protein adsorption studies were carried out on a series of additive dispersed and additive coated poly(ether urethane ureas), PEUUs, to characterize early events in the blood compatibility of these materials. A hypothesis that is based on surface hydrophilicity, surface flexibility, and adsorption media has been developed to understand the modulated adsorption of plasma proteins by PEUU additives. Electron spectroscopy for chemical analysis (ESCA) and contact angle analysis were performed on two PEUU formulation as well as on PEUU formulations modified with Methacrol 2138F (co[diisopropylaminoethyl methacrylate (DIPAM)/decyl methacrylate (DM)][3/1]) or acrylate or methacrylate polymer or copolymer analogs of Methacrol 2138F. Methacrol 2138F is a commercially used amphiphilic copolymethacrylate. ESCA showed that the PEUUs loaded with Methacrol 2138F or with its hydrophilic component, homopoly (DIPAM) (h-(DIPAM)), had a higher percentage of nitrogen at their surfaces than did the base PEUUs. Contact angle analysis also showed that the air side of PEUU formulations loaded with Methacrol 2138F were more hydrophobic than was the air side of base PEUUs when films were cast from dimethylacetamide. However, during contact angle testing, the air side of PEUU films loaded with Methacrol 2138F rapidly became more hydrophilic than did the air side of the base PEUU films. A radioimmunoassay and whole or diluted human plasma were also used to characterize the presence of the proteins fibrinogen, immunoglobulin G, factor VIII/von Willebrand factor, Hageman factor (factor XII), and albumin, on the surface of the same PEUUs as analyzed by ESCA and contact angle. The protein adsorption assay showed that PEUU films loaded or coated with Methacrol 2138F, with a copolyacrylate analog of Methacrol 2138F (co(diisopropylaminoethyl acrylate [DIPAA]/decyl acrylate [DA]) [3/1]), or with the hydrophilic polyacrylate or polymethacrylate component analogs of Methacrol 2138F (h-DIPAM or h-DIPAA) adsorbed significantly lower amounts of the proteins than did either the base PEUU formulations or the homopoly(decyl methacrylate) (h-DM) or homopoly(decyl acrylate) (h-DA) coated or loaded PEUUs.