Semiempirical,squeeze flow,and intermolecular diffusion model. II. Model verification using laser microwelding

This article reviews the application of a coupled squeeze flow and intermolecular diffusion model, which was used to predict the quality and size of microwelds in plastics. Weld widths predictions were compared with previously presented experimental results using moving heat source models and temperature fields. The motivation for this work was to develop and verify a model based on fundamental principles that could accurately predict weld size and strength for conventional plastic welding techniques as well as novel techniques such as laser microwelding. It is envisioned that the resulting model could be used to predict proper welding parameters, including laser power and travel speed, to produce welds of varying size. Although insight into weld quality can be derived from this model, it was not the goal of this work to accurately predict weld strength for laser microwelding because of the difficulty in measuring weld strength on the micron scale. However, as reported in Part 1, weld strength for impulse welds were accurately predicted. In this model it was found that variable temperature histories, rather than a single value of maximum weld temperature, allows more accurate modeling of the welding process. In this work (Part 2), microwelds as small as 11 μm in width were produced with transmission infrared welding. In addition, welds over 150‐μm wide were also generated and the model was able to predict the range of weld widths that were found experimentally. It was found that the predictions were in very good agreement with the experimental results. There was some deviation between the experimental data and the model at the extreme parameters and it is believed that this was due to the temperature‐dependent material properties as well as optical aberrations. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Molecular follow-up of disease progression and interferon therapy in chronic myelocytic leukemia

We previously reported that the abl promoter (Pa) undergoes de novo DNA methylation in the course of chronic myelocytic leukemia (CML). The clinical implications of this finding are the subject of the present study in which samples of CML patients, including a group treated with interferon alpha (IFNalpha) were surveyed. The methylation status of the abl promoter was monitored by polymerase chain reaction (PCR) amplification of the Pa region after digestion with several site-methylation sensitive restriction enzymes. Some 74% of the DNA samples from blood and marrow drawn in the chronic phase were nonmethylated, similar to control samples from non-CML patients. The remaining 26% were partially methylated in the abl Pa region. The latter samples were derived from patients who were indistinguishable from the others on the basis of clinical presentation. Methylated samples were mostly derived from patients known to have a disease of longer duration (26 months v 7.5 months, P = .01). Samples of 30 IFNalpha-treated patients were sequentially analyzed in the course of treatment. Fifteen patients with no evidence of Pa methylation before treatment remained methylation-free. The remainder, who displayed Pa methylation before treatment, reverted to the methylation-free status. The outcome is attributed to IFNalpha therapy, as the Pa methylation status was not reversed in any of the patients treated with hydroxyurea. Methylation of the abl promoter indicates a disease of long-standing, most likely associated with a higher probability of imminent blastic transformation. It appears to predict the outcome of IFNalpha therapy far better than the cytogenetic response.     

"I Buy American": The American Image as Reflected in Israeli Advertising

Analysis of advertisements in Israeli newspapers over the past decade has shown that American symbols have been widely used to market an array of consumer goods. Products made in America, Israel, or other countries are marketed with some sort of American angle by invoking America's values, symbols, landscapes, or lifestyle. Using both qualitative and quantitative methods, we analyzed how central components of the nation-state/national sphere—language, flag, political leaders, borders, landscapes, and sights—are reflected in advertising. We attempt to show how social values metamorphose, shedding their "Israeliness" and taking on an American veneer. Using Israel as an example may provide a test case for the Americanization process in other societies at the turn of the millennium.     

RAFTK, a novel member of the focal adhesion kinase family, is phosphorylated and associates with signaling molecules upon activation of mature T lymphocytes

The related adhesion focal tyrosine kinase (RAFTK), a recently discovered member of the focal adhesion kinase family, has previously been reported to participate in signal transduction in neuronal cells, megakaryocytes, and B lymphocytes. We have found that RAFTK is constitutively expressed in human T cells and is rapidly phosphorylated upon the activation of the T cell receptor (TCR). This activation also results in an increase in the autophosphorylation and kinase activity of RAFTK. After its stimulation, there was an increase in the association of the src cytoplasmic tyrosine kinase Fyn and the adapter protein Grb2. This association was mediated through the SH2 domains of Fyn and Grb2. RAFTK also co-immunoprecipitates with the SH2 domain of Lck and with the cytoskeletal protein paxillin through its COOH-terminal proline-rich domain. The tyrosine phosphorylation of RAFTK after T cell receptor-mediated stimulation was reduced by the pretreatment of cells with cytochalasin D, suggesting the role of the cytoskeleton in this process. These observations indicate that RAFTK participates in T cell receptor signaling and may act to link signals from the cell surface to the cytoskeleton and thereby affect the host immune response.     

Ultrasonic welding of thermoplastics in the far-field

In far-field ultrasonic welding of plastic parts the distance between the ultrasonic horn and the joint is greater than 6 mm. This study investigated the farfield ultrasonic welding of amorphous (acrylo butadiene styrene and polystyrene) and semicrystalline (polyethylene and polypropylene) polymers. Far-field welding worked well for amorphous polymers. Weld strength improved substantially with increasing amplitude of vibration at the joint interface. Increasing the weld pressure and/or the weld time also resulted in higher weld strengths. Far-field ultrasonic welding was not successful for semicrystalline polymers. The parts melted and deformed at the horn/part interface with little or no melting at the joint interface. A model for wave propagation in viscoelastic materials, which was developed to predict the vibration amplitude experienced at the joint interface, indicates that increasing the length of the samples to a half a wavelength should improve the far-field welding of semicrystalline polymers by maximizing the amplitude of vibration at the joint interface.     

Computing the Ramsey number R(4,3,3) using abstraction and symmetry breaking

The number R(4, 3, 3) is often presented as the unknown Ramsey number with the best chances of being found “soon”. Yet, its precise value has remained unknown for almost 50 years. This paper presents a methodology based on abstraction and symmetry breaking that applies to solve hard graph edge-coloring problems. The utility of this methodology is demonstrated by using it to compute the value R(4, 3, 3) = 30. Along the way it is required to first compute the previously unknown set \(\mathcal {R}(3,3,3;13)\) consisting of 78,892 Ramsey colorings.     

Linear and nonlinear viscoelastic and viscoplastic analysis of asphalt binders with warm mix asphalt additives

Warm-Mix Asphalt (WMA) is a widely used product, which proved a contribution to the reduction in asphalt mixing and compaction temperatures. This reduction leads to lower fuel consumption and smoke emission in asphalt plants. Most of the characterisation of binders used in WMA has focused in the past on measuring linear viscoelastic properties and associated Superpave parameters. Several studies have shown that the average stresses and strains of the asphalt mixture remain mostly within the linear viscoelastic response. However, localised strains in the binder phase of the mixture could reach values high enough to induce nonlinear viscoelastic and viscoplastic deformations. Therefore, this study focuses on an experimental and analytical evaluation of linear, nonlinear viscoelastic and viscoplastic responses of selected binders modified for use in WMA. The first part of the paper analyses the linear viscoelastic material properties and their ability to evaluate permanent deformation resistance. Then, the non-recoverable creep compliance parameter obtained from the Multiple Stress Creep Recovery (MSCR) test is analysed to assess the nonlinear response and permanent deformation of asphalt binders. The paper utilises a nonlinear plasto-viscoelastic (NPVE) approach to assess and quantify the nonlinear plasto-viscoelastic response of binders by separating the recoverable and irrecoverable strains measured in the MSCR test. Two WMA additives were included in this study by mixing them with polymer-modified and unmodified asphalt binders. Analysis of results showed that the NPVE approach captured a higher percentage of recovery than the NLVE approach. However, binder’s performance evaluation and ranking did not change by adopting the NPVE approach. The nonlinear viscoelastic parameters provided insight on the behaviour of asphalt binders mixed with WMA additives during loading cycles. Sasobit showed higher influence than Advera on binders in resisting permanent deformation by increasing the recoverable strain during the unloading phase.     

NRP/B, a novel nuclear matrix protein, associates with p110(RB) and is involved in neuronal differentiation

The nuclear matrix is defined as the insoluble framework of the nucleus and has been implicated in the regulation of gene expression, the cell cycle, and nuclear structural integrity via linkage to intermediate filaments of the cytoskeleton. We have discovered a novel nuclear matrix protein, NRP/B (nuclear restricted protein/brain), which contains two major structural elements: a BTB domain-like structure in the predicted NH2 terminus, and a "kelch motif" in the predicted COOH-terminal domain. NRP/B mRNA (5.5 kb) is predominantly expressed in human fetal and adult brain with minor expression in kidney and pancreas. During mouse embryogenesis, NRP/B mRNA expression is upregulated in the nervous system. The NRP/B protein is expressed in rat primary hippocampal neurons, but not in primary astrocytes. NRP/B expression was upregulated during the differentiation of murine Neuro 2A and human SH-SY5Y neuroblastoma cells. Overexpression of NRP/B in these cells augmented neuronal process formation. Treatment with antisense NRP/B oligodeoxynucleotides inhibited the neurite development of rat primary hippocampal neurons as well as the neuronal process formation during neuronal differentiation of PC-12 cells. Since the hypophosphorylated form of retinoblastoma protein (p110(RB)) is found to be associated with the nuclear matrix and overexpression of p110(RB) induces neuronal differentiation, we investigated whether NRP/B is associated with p110(RB). Both in vivo and in vitro experiments demonstrate that NRP/B can be phosphorylated and can bind to the functionally active hypophosphorylated form of the p110(RB) during neuronal differentiation of SH-SY5Y neuroblastoma cells induced by retinoic acid. Our studies indicate that NRP/B is a novel nuclear matrix protein, specifically expressed in primary neurons, that interacts with p110(RB) and participates in the regulation of neuronal process formation.     

Novel nano polymeric system containing biosynthesized core shell silver/silica nanoparticles for functionalization of cellulosic based material

An innovative strategy for functional finishing of cellulosic based materials is based on the incorporation of a thin layer of surface modifying systems (SMS) in the form of stimuli-sensitive nanogels containing combining metal nanoparticles and silica. The silver–silica core–shell nanoparticles (NPs) were synthesized by simple one pot chemical method. Silica/silver nanoparticles have been synthesized using low concentration of dextran as reducing and stabilizing agent and using ascorbic acid as antioxidant agent. The core–shell NPs were characterized for their structural, morphological, compositional and optical behaviour using X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis. Stimuli-responsive nanogel was prepared by copolymerization of poly(N-isopropylacrylamide) with pullulan, results in a nanogel that is responsive to both temperature and pH, the nano-particulate hydrogel of poly-NiPAAm-pullulan copolymer was synthesized using surfactant-free emulsion method. The prepared nano-particles were used during the preparation steps of the pullulan nanogel to obtain nanogel/combining metal/silica NPs to produce a composite materials. The nanoparticle size in dry (collapsed) state is estimated at 250 nm by SEM and TEM, and effect of temperature and pH on gel-nanoparticles was investigated by DLS and UV–vis spectrophotometry. The incorporation of the nanoparticles to cellulosic material was done by a simple pad dry-cure procedure from aqueous nanoparticle dispersion that contained a cross-linking agent. This application method provided sufficient integrity to coating by maintaining the responsiveness of surface modifying system. The stimuli responsiveness of modified cellulosic materials has been confirmed in terms of regulating its water uptake in dependence of pH and temperature.