Thermoresponsive oligo(ethylene glycol) methacrylate colloids with antifouling surface properties

Thermoresponsive polymeric colloids attract great attention in several biotechnological applications owing to their ability to manipulate drug release characteristics in a controlled manner. Majority of these applications utilized N‐isopropylacrylamide (NIPAM)‐based particles for controlled drug release. Despite its advantages, such as easy chemical modification and well‐documented literature, a potentially important bottleneck for NIPAM in biological applications is its tendency for nonspecific protein adsorption. Herein, we report a simple way to prepare novel thermoresponsive colloids composed of oligo(ethylene glycol) side chains via precipitation polymerization technique. In addition to displaying highly reversible thermal response, these particles also have considerably low nonspecific protein adsorption when compared with NIPAM counterparts. These crosslinked poly(ethylene glycol) ethyl ether methacrylate particles were characterized using dynamic light scattering and transmission electron microscopy. The effects of co‐monomer, crosslinker and initiator on particle characteristics were investigated. Finally, particle toxicity studies were carried out using 3T3 fibroblast cell lines in MTT cytotoxicity assay. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Stability analysis of N-model systems under a static priority rule

We consider the stability of N-model systems that consist of two customer classes and two server pools. Servers in one of the pools can serve both classes, but those in the other pool can serve only one of the classes. The standard fluid models in general are not sufficient to establish the stability region of these systems under static priority policies. Therefore, we use a novel and a general approach to augment the fluid model equations based on induced Markov chains. Using this new approach, we establish the stability region of these systems under a static priority rule with thresholds when the service and interarrival times have phase-type distributions. We show that, in certain cases, the stability region depends on the distributions of the service and interarrival times (beyond their mean), on the number of servers in the system, and on the threshold value. We also show that it is possible to expand the stability region in these systems by increasing the variability of the service times (without changing their mean) while keeping the other parameters fixed. The extension of our results to parallel server systems and general service time distributions is also discussed.     

Numerical stabilities of loosely coupled methods for robust modeling of lightweight and flexible structures in incompressible and viscous flows

The growing interest to examine the hydroelastic dynamics and stabilities of lightweight and flexible materials requires robust and accurate fluid–structure interaction(FSI)models. Classically, partitioned fluid and structure solvers are easier to implement compared to monolithic methods;however, partitioned FSI models are vulnerable to numerical("virtual added mass") instabilities for cases when the solid to fluid density ratio is low and if the flow is incompressible.As a partitioned method, the loosely hybrid coupled(LHC)method, which was introduced and validated in Young et al.(Acta Mech. Sin. 28:1030–1041, 2012), has been successfully used to efficiently and stably model lightweight and flexible structures. The LHC method achieves its numerical stability by, in addition to the viscous fluid forces, embedding potential flow approximations of the fluid induced forces to transform the partitioned FSI model into a semi-implicit scheme. The objective of this work is to derive and validate the numerical stability boundary of the LHC. The results show that the stability boundary of the LHC is much wider than traditional loosely coupled methods for a variety of numerical integration schemes. The results also show that inclusion of an estimate of the fluid inertial forces is the most critical to ensure the numerical stability when solving for fluid–structure interaction problems involving cases with a solid to fluid-added mass ratio less than one.     

Non-isotopic symplectic tori in the same homology class

For any pair of integers and , we construct an infinite family of mutually non-isotopic symplectic tori representing the homology class of an elliptic surface , where is the homology class of the fiber. We also show how such families can be non-isotopically and symplectically embedded into a more general class of symplectic -manifolds.

     

Nickel ion as a template in the synthesis of macrocyclic imine-oxime complexes from carbonyl compounds and o-phenylenediamine

A new series of macrocyclic imine-oxime complexes prepared by template condensation of o-phenylenediamine, phthaldialdehyde, 2,6-diacetylpyridine and dichloroglyoxime in MeOH solution, have been characterized by i.r., electronic spectral data, elemental analyses, conductivity and magnetic susceptibility measurements. In the imine moiety of the complexes, the chloride ions coordinate to the nickel ion. From conductivity measurements, it was shown that the complexes are not all electrolytes. Their thermal behaviour has been studied by the t.g. and d.t.a. analysis. They decompose with loss of the organic ligand and halogen to leave the metal oxide.     

Optical phase cloaking of 700 nm light waves in the far field by a three-dimensional carpet cloak

Transformation optics is a design tool that connects the geometry of space and propagation of light. Invisibility cloaking is a corresponding benchmark example. Recent experiments at optical frequencies have demonstrated cloaking for the light amplitude only. In this Letter, we demonstrate far-field cloaking of the light phase by interferometric microscope-imaging experiments on the previously introduced three-dimensional carpet cloak at 700 nm wavelength and for arbitrary polarization of light.     

A review of recent research on green road freight transportation

Road freight transportation is a major contributor to carbon dioxide equivalent emissions. Reducing these emissions in transportation route planning requires an understanding of vehicle emission models and their inclusion into the existing optimization methods. This paper provides a review of recent research on green road freight transportation.     

Yolk-Shell Nanostars@Metal Organic Frameworks as Molecular Sieves for Optical Sensing and Catalysis

Hybrid composites between nanoparticles and metal organic frameworks (MOFs) have been described as optimal materials for a wide range of applications in optical sensing, drug delivery, pollutant removal or catalysis. These materials are usually core-shell single- or multi-nanoparticles, restricting the inorganic surface available for reaction. Here, we develop a method for the preparation of yolk-shells consisting in a plasmonic gold nanostar coated with MOF. This configuration shows more colloidal stability, can sieve different molecules based on their size or charge, seems to show some interesting synergy with gold for their application in photocatalysis and present strong optical activity to be used as SERS sensors.     

Copolymer formation of 9-(2-(benzyloxy)ethyl)-9H-carbazole and 1-tosyl-1H-pyrrole coated on glassy carbon electrode and electrochemical impedance spectroscopy

In this work, 9-(2-(benzyloxy)ethyl)-9H-carbazole (BzOCz) and 1-tosyl-1H-pyrrole (TsP) monomers were chemically synthesized and characterized by Fourier transform infrared reflectance (FTIR) and proton nuclear magnetic resonance (¹H-NMR) spectroscopy. BzOCz and TsP were electrocoated on glassy carbon electrode (GCE) in various molar fractions (X _TsP?=?0.5, 0.83, 0.91, and 0.98) in 0.1?M sodium perchlorate/acetonitrile. The detailed characterization of poly(BzOCz-co-TsP) was studied by cyclic voltammetry, FTIR-attenuated total reflection spectroscopy and electrochemical impedance spectroscopy (EIS). The effects of different molar fractions during the preparation of modified electrodes were studied by EIS technique. The AC impedance technique was used to determine the capacitive behaviors of modified GCE via Nyquist, Bode magnitude, and Bode phase plots. The highest low frequency capacitance value was obtained as C _LF?=?23.94?μF?cm^?2 for X _TsP?=?0.98. Therefore, synthesized copolymer has more capacitive behavior than its homopolymers, such as C _LF?=?7.5?μF?cm^?2 for poly(BzOCz) and C _LF?=?9.44?μF?cm^?2 for poly(TsP). In order to interpret the AC impedance spectra, R(Q(RW)) electrical equivalent circuit was employed with linear Kramers–Kronig test. A mechanism for electropolymerization has been proposed for copolymer formation.     

Testing a two-state model of nanoconfined liquids: conformational equilibrium of ethylene glycol in amorphous silica pores

Molecular dynamics simulations of the conformational equilibrium of ethylene glycol in roughly cylindrical nanoscale amorphous silica pores are presented and analyzed in the context of a two-state model of confined liquids. This model assumes that an observable property of a confined liquid can be decomposed into a weighted average arising from two subensembles with distinct physical attributes: molecules at the surface and molecules in the interior of the pore. It is further assumed that the molecules in the interior exhibit behavior that is indistinguishable from that of the bulk liquid. However, the present simulation results are not consistent with this two-state model. Neither the assumption of two distinct subensembles nor the assumption that the interior molecules possess bulk-like behavior is supported.