Improving the antifouling properties of polypropylene surfaces by melt blending with polyethylene glycol diblock copolymers

Protein‐resistant polyethylene‐block‐poly(ethylene glycol) (PE‐b‐PEG) copolymers of different molecular weights at various concentrations were compounded by melt blending with polypropylene (PP) polymers in order to enhance their antifouling properties. Phase separation of the PE‐b‐PEG copolymer and its migration to the surface of the PP blend, was confirmed by attenuated total reflectance–Fourier transform infrared, X‐ray photoelectron spectroscopy, and static water contact angle measurements. Enrichment of PEG chains at the surface of the blends increased with increasing PE‐b‐PEG copolymer concentration and molecular weight. The PP blends compounded with PE‐b‐PEG copolymer having the lowest molecular weight (875 g mol^?1), at the lowest concentration (1 wt %), gave the lowest bovine serum protein adsorption (30% less) compared to that of neat PP. At higher concentrations (5 and 10 wt %), and higher molecular weights (920, 1400, and 2250 g mol^?1), the PE‐b‐PEG copolymers leached‐out resulting in protein adsorption comparable to that of neat PP. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46122.     

Performance analysis of parallel identical machines with a generalized shortest queue arrival mechanism

In this paper we study a production system consisting of a group of parallel machines producing multiple job types. Each machine has its own queue and it can process a restricted set of job types only. On arrival a job joins the shortest queue among all queues capable of serving that job. Under the assumption of Poisson arrivals and identical exponential processing times we derive upper and lower bounds for the mean waiting time. These bounds are obtained from so-called flexible bound models, and they provide a powerful tool to efficiently determine the mean waiting time. The bounds are used to study how the mean waiting time depends on the amount of overlap (i.e. common job types) between the machines.

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Received: February 8, 2000 / Accepted: November 28, 2000     

The shape of action.

How do people understand the everyday, yet intricate, behaviors that unfold around them? In the present research, we explored this by presenting viewers with self-paced slideshows of everyday activities and recording looking times, subjective segmentation (breakpoints) into action units, and slide-to-slide physical change. A detailed comparison of the joint time courses of these variables showed that looking time and physical change were locally maximal at breakpoints and greater for higher level action units than for lower level units. Even when slideshows were scrambled, breakpoints were regarded longer and were more physically different from ordinary moments, showing that breakpoints are distinct even out of context. Breakpoints are bridges: from one action to another, from one level to another, and from perception to conception. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Deep level defects in Au/ZnSe Schottky diodes

Properties of deep level defects in heteroepitaxially grown ZnSe have been investigated using transient capacitance spectroscopy. A total of five electron traps were observed with activation energies of 0.33, 0.35, 0.42, 0.71 and 0.86 eV in Au/ZnSe Schottky diodes. Trap concentrations ranged from 1012 to 1014 cm?3.     

The MIRD perspective 1999. Medical Internal Radiation Dose Committee

The MIRD schema is a general approach for medical internal radiation dosimetry. Although the schema has traditionally been used for organ dosimetry, it is also applicable to dosimetry at the suborgan, voxel, multicellular and cellular levels. The MIRD pamphlets that follow in this issue and in coming issues, as well as the recent monograph on cellular dosimetry, demonstrate the flexibility of this approach. Furthermore, these pamphlets provide new tools for radionuclide dosimetry applications, including the dynamic bladder model, S values for small structures within the brain (i.e., suborgan dosimetry), voxel S values for constructing three-dimensional dose distributions and dose-volume histograms and techniques for acquiring quantitative distribution and pharmacokinetic data.     

Testing of Frank's hypothesis on a containerless packing of macroscopic soft spheres and comparison with mono-atomic metallic liquids

It is well-known that metallic liquids can exist below their equilibrium melting temperature for a considerable time. To explain this, Frank [1] proposed that icosahedral ordering, incompatible with crystalline long-range order, is prevalent in the atomic structure of these liquids, stabilizing them and enabling them to be supercooled. Some studies of the atomic structures of metallic liquids using Beam-line Electrostatic Levitation (BESL; containerless melting), and other techniques, support this hypothesis [2], [3]. Here we examine Frank's hypothesis in a system of macroscopic, monodisperse deformable spheres obtained by containerless packing under the influence of centripetal force. The local structure of this packing is analyzed and compared with atomic ensembles of liquid transition metals obtained by containerless melting using the BESL method.     

Inorganic Halide Perovskitoid TlPbI3 for Ionizing Radiation Detection

Room temperature semiconductor detector (RTSD) materials for γ-ray and X-ray radiation are in great demand for the nonproliferation of nuclear materials as well as for biomedical imaging applications. Halide perovskites have attracted great attention as emerging and promising RTSD materials. In this contribution, the material synthesis, purification, crystal growth, crystal structure, photoluminescence properties, ionizing radiation detection performance, and electronic structure of the inorganic halide perovskitoid compound TlPbI₃ are reported on. This compound crystallizes in the ABX₃ non-perovskite crystal structure with a high density of d = 6.488 g·cm^–3, has a wide bandgap of 2.25 eV, and melts congruently at a low temperature of 360 °C without phase transitions, which allows for facile growth of high quality crystals with few thermally-activated defects. High-quality TlPbI₃ single crystals of centimeter-size are grown using the vertical Bridgman method using purified raw materials. A high electrical resistivity of ≈10¹² Ω·cm is readily obtainable, and detectors made of TlPbI₃ single crystals are highly photoresponsive to Ag K_α X-rays (22.4 keV), and detects 122 keV γ-rays from ⁵⁷Co radiation source. The electron mobility-lifetime product µ_eτ_e was estimated at 1.8 × 10^–5 cm²·V^–1. A high relative static dielectric constant of 35.0 indicates strong capability in screening carrier scattering and charged defects in TlPbI₃.     

Three-dimensional nanoscale composition mapping of semiconductor nanowires

We demonstrate the three-dimensional composition mapping of a semiconductor nanowire with single-atom sensitivity and subnanometer spatial resolution using atom probe tomography. A new class of atom probe, the local electrode atom probe (LEAP) microscope, was used to map the position of single Au atoms in an InAs nanowire and to image the interface between a Au catalyst and InAs in three dimensions with 0.3-nm resolution. These results establish atom probe tomography as a uniquely powerful tool for analyzing the chemical composition of semiconductor nanostructures.