Rotaxane‐Like Structures Threaded through the Pores of Hollow Porous Nanocapusles

Nanocapsules with molecules threaded through the porous shells may lead to advanced cell‐mimicking functional devices. Herein, we show the feasibility of synthesizing such hybrid nanostructures by using vesicle‐templated polymer nanocapsules with controlled nanopores. Ship‐in‐a‐bottle assembly inside a nanocapsule created an internal unit. An external unit was then connected to an entrapped internal unit through pre‐attached linker threaded through a nanopore in the shell of the nanocapsule. Both internal and external units are larger than the pore size and cannot cross the shell, producing a rotaxane‐like structure. Successful synthesis was achieved with fairly short linkers (six and ten carbon atoms in a chain), creating an opportunity for facile synthesis of functional devices capable of cross‐shell communication.     

Parallelizing Tabu Search on a Cluster of Heterogeneous Workstations

In this paper, we present the parallelization of tabu search on a network of workstations using PVM. Two parallelization strategies are integrated: functional decomposition strategy and multi-search threads strategy. In addition, domain decomposition strategy is implemented probabilistically. The performance of each strategy is observed and analyzed. The goal of parallelization is to speedup the search in finding better quality solutions. Observations support that both parallelization strategies are beneficial, with functional decomposition producing slightly better results. Experiments were conducted for the VLSI cell placement, an NP-hard problem, and the objective was to achieve the best possible solution in terms of interconnection length, timing performance (circuit speed), and area. The multiobjective nature of this problem is addressed using a fuzzy goal-based cost computation.     

Calculation and Experimental Study of a Two-Way Reinforced Rubber-Cord Composite in Tension

A rubber-cord composite, reinforced in two directions with fibers of polyamide cord, under large tensile deformations is investigated based on calculations of a rubber-cord composite material and on tensile tests of specimens made of the casing of a diagonal truck tire. A method of the experimental tensile testing of rubber-cord composite specimens is described. The calculations are based on the carcass theory of composite materials. The calculated and experimental parameters of the macroscopic strains of the rubber tire cord and of its structure in a deformed configuration are given. The manifestation of edge effects in relation to the reinforcement angle is described.     

Berührungslose Geschwindigkeitsmessung eines Fadens durch punktofömige radioaktive Markierung

Es wird ein Verfahren beschrieben, das zur Messung eines sich bewegenden Fadens geeignet ist. Die Messung erfolgt ohne Berührung des Fadens. Vor der Messung werden unter Verwendung von radioaktiver Phosphorsäure (³²P) auf dem Faden einzelne Stellen markiert. Die Messung der Geschwindigkeit erfolgt durch eine Zeitintervallmessung. Es werden handelsübliche Geräte verwendet, die durch ihre Ein- und Ausgänge nach einem bestimmten Funktionsplan verbunden sind. Als praktisches Beispiel dienen Messungen an einer Falschdraht-Texturiermaschine.     

Valve Tissue Engineering with Living Absorbable Threads

Tissue engineering (TE) depends on the population of scaffolds with appropriate cells, arranged in a specific physiological direction using a variety of techniques. Here, a novel technique of creating “living threads” is described based on thin (poly(ε‐caprolactone) fibers of different diameters (23–243 μm). The fibers readily attract human mesenchymal stem cells (MSCs), which are firmly adhered. These versatile fibers can be used to produce dimensional shapes identical in shape to the cup‐like structure of a normal human valve, while preserving the specific orientation of both the cells and the fibers. The MSCs on leaflets and the cells cultured in flask shown similar epitopes expression when analyzed by fluorescence activated cell sorting. Together, these characteristics have important functional implications as living absorbable fibers can be a valuable resource in TE of living tissues, including heart valves.

     

Polymer “threads” and drag reduction

A number of different polymer fluids were ejected on the centerline of a water pipe-flow facility. Two distinct flow regions were identified: Reynolds numbers above 25000, where centerline injection acted as a rather efficient mixing device for water-soluble polymer — and no drag-reduction resulted from non water-soluble materials; and Reynolds numbers from 10000 to 25000, where strong evidence exists that under certain conditions, a viscoelastic fluid thread can interact with turbulence eddies and reduce the overall flow friction in the pipe.On Sabbatical leave from San Diego State University.     

The influence of surface treatment of stitch threads and stitching on interlaminar properties of unidirectional laminates

An experimental investigation was carried out to study the influence of graft treatment for Kevlar stitch threads on the interlaminar properties of stitched unidirectional laminates. The surfaces of Kevlar stitch threads were immersed in a solution of Dimethyl sulfoxide mixed with NaH for some time, and then alkoxysilane was grafted onto the surface of modified Kevlar threads. The corresponding physical and chemical changes in the surface of Kevlar threads were carefully evaluated using XPS, SEM, water absorption, and tensile measurement. Results show that the treated Kevlar threads have much rougher surface morphologies, its tensile strength is slightly improved, and their wettability are greatly improved. The stitched carbon /epoxy composite using surface-treated Kevlar threads has excellent hydrothermal property. The resins can better wet the surface treatment of Kevlar stitch threads, and the sizes of rich resin can be reduced. The moisture uptake of stitched composites decreases by 53.3% and its residue ratio of interlaminar shear strength in a wet state improves by 13.1%.     

New multifunctional biocomposite material for hydrocarbon detection and reclamation on the surface of water areas

1. Download : Download high-res image (222KB)
2. Download : Download full-size image

     

Surface‐enhanced Raman scattering (SERS) and complementary techniques applied for the investigation of an Italian cultural heritage canvas

A cultural heritage canvas from the early 19^th century, painted by the Vaccaro brothers for the church of Niscemi, province of Caltanissetta, Sicily, was analyzed using Fourier transform (FT)‐Raman, attenuated total reflectance‐FT‐infrared and surface enhanced Raman scattering (SERS) spectroscopy. The painting, still used in religious rites related to the Easter mass (‘la calata da tila’), depicts the scene of the Crucifixion and is executed in a scarce palette, with white, green and blue colors. Analysing vibrational data in conjunction with scanning electron microscopy and solid ‐state ¹³C‐NMR signals of the linen threads, we were able to offer valuable insight into the painting technique, unknown prior to this study. SERS is usually employed in artwork diagnosis for the identification of organic lakes and dyes. Due to its sensitivity, SERS has been successfully applied for the detection of either organic painting materials (indigo) that are usually not resolved by conventional Raman spectroscopy or of inorganic pigments difficult to observe in the presence of highly fluorescent aged organic supports or binders. To the best of our knowledge, this is also the first report on the SERS investigation of flax used in linen from cultural heritage objects using Ag colloidal nanoparticles. Copyright © 2012 John Wiley & Sons, Ltd.     

Analytical Solutions of Nonlinear Static Problems for Threads of Finite Stiffness Under Active Loading

The behavior of elastoplastic threads of finite stiffness under lateral bending is analyzed. Geometrical and physical nonlinearities are taken into account. The material is assumed to be elastoplastic. The nonlinear equations describing the stress—strain state of threads are derived using the virtual-displacement principle. Numerical results are discussed __________ Translated from Prikladnaya Mekhanika, Vol. 41, No. 6, pp. 121–129, June 2005.