Random Copolymers with 2,2′-Dioxy-1,1′-biphenyl-phosphazene and Chiral 2,2′-dioxy-1,1′-binaphthylphosphazene Units Functionalized in the 6,6′-Positions with PPh<Subscript>2</Subscript> Groups as Precursors for Ru(arene) Catalysts

The chiral phosphazene copolymers {[NP(O₂C₁₂H₈)]_0.9[NP(O₂C₂₀H₁₂)]_0.1} (1) and {[NP(O₂C₁₂H₈)]_0.9[NP(O₂C₂₀H₁₀Br₂)]_0.1} _n (2) [(O₂C₁₂H₈) = 2,2′-dioxy-1,1′-biphenyl; (O₂C₂₀H₁₂) = R-2,2′-dioxy-1,1′-binaphthyl and (O₂C₂₀H₁₀Br₂) = R-6,6′-dibromo-2,2′-dioxy-1,1′-binaphthyl] were prepared by sequential substitution from [NPCl₂] _n and the corresponding dihydroxy-biphenyl or binaphthyl reagents in the presence of Cs₂CO₃ and K₂CO₃. The reaction of (2) with ^tBuLi in THF, followed by addition of PPh₂Cl and a treatment with SiHCl₃/PPh₃ to eliminate any oxidized OC₆H₄P(O)Ph₂ groups, gave the phosphine containing copolymer {[NP(O₂C₁₂H₈)]_0.9[NP(O₂C₂₀H₁₀[PPh₂]₂)]_0.1} _n (3), that was used as a chiral ligand to support [Ru(p-cymene)Cl] complexes. The resulting catalyst was active for hydrogen transfer from isopropyl alcohol to acetophenone but the placement of the Ru centers in the 6,6′-positions of the binaphthoxyphosphazene units induced no enantioselectivity. Dedicated to Professor Christopher Allen.     

Restructuring butterfat through blending and chemical interesterification. 3. Rheology

Interesterified and noninteresterified butterfat-canola oil blends, ranging from 100% butterfat to 60∶40 butterfat-canola oil (w/w) in 10% increments, were evaluated for hardness index (HI), dropping point, viscosity, and viscoelastic properties at small deformation. Both blending and chemical interesterification diminished HI in a nonlinear fashion. HI changes in interesterified blends were more pronounced than in noninteresterified blends. Dropping points yielded information on the structure of the blends. Butterfat’s dropping point (DP) was 34.4°C, whereas that of interesterified butterfat was 37.0°C, which is indicative of a more structured network for the latter. DP values of blends with 60–90% butterfat (interesterified vs. noninteresterified) were not significantly different (P<0.05). Interesterified blends had a higher crystallization onset temperature than did noninteresterified blends. All blends in the liquid state displayed Newtonian behavior. Oscillatory frequency sweep measurements at small amplitude showed that interesterified blends generally had lower storage moduli (G′) than their noninteresterified counterparts. BothG′ andG″ were frequency-dependent. Replacement of 30% butterfat by canola oil led to notable changes in small deformation measurements, whereas replacement of 20% butterfat led to big changes in large deformation measurements.     

<Emphasis Type="Italic">In situ</Emphasis> monitoring of solid fat content by means of pulsed nuclear magnetic resonance spectrometry and ultrasonics

An ultrasonic technique was developed to study the crystallization process of edible fats on-line. A chirp wave was used instead of the conventional pulser signal, thus achieving a higher signal-to-noise ratio. This enabled measurements to be made in concentrated systems [≈20% solid fat content (SFC)] through a 8.11-cm thick sample without significant signal loss. Fat samples were crystallized at 20, 25, and 30°C at a constant agitation rate of 400 rpm for 90 min. The crystallization process was followed by ultrasonic spectroscopy and a low-resolution pulsed nuclear magnetic resonance spectrometer. Specific relationships were found between ultrasonic parameters [integrated response, time of flight (TF), and full width half maximum] and SFC. TF, which is an indirect measurement of the ultrasonic velocity (v), was highly correlated to SFC (r ²>0.9) in a linear fashion (v=2.601 SFC+1433.0).     

Analytic expressions for the isosteric heat of adsorption from adsorption isotherm models and two-dimensional SAFT-VR equation of state

The isosteric heat of adsorption is an important thermodynamic property used to characterize and optimize adsorption processes. In this work, analytic expressions for isosteric heats of adsorption are derived for a collection of commonly used isotherm models and a two-dimensional molecular equation of state based on the SAFT-VR approach. The use of these expressions is presented with an example of adsorption of nitrous oxide, N₂O, on biochar, which is a waste biomass charcoal that exhibits high adsorption potential. The results show that accurate fitting of the adsorption isotherms leads to consistent results obtained with different approaches; however, the predicted isosteric heat of adsorption exhibits strong variations in the regions where experimental data is insufficient such in the region of low pressure/low coverage. Convergence on the prediction of the isosteric heat of adsorption by the different models is only observed in the region where no extrapolation of experimental data is needed.     

Influence of deposited amine-functionalized Si-MCM-41 in polyacrylonitrile electrospun membranes applied for separation of water in oil emulsions

Among several oil/water emulsion separation technologies, the utilization of nanoparticle-decorated membranes with diverse functionalities has received considerable attention in recent years, particularly if the antifouling capacity can be improved. In this article, we propose a new membrane based on surface-hydrolyzed polyacrylonitrile electrospun membranes and/or decorated with amine-functionalized Si-MCM-41 nanoparticles to be used as oil/water emulsion separation treatment and to determine their antifouling ability. X-Ray photoelectron spectrometry, attenuated total reflectance Fourier transform infrared spectroscopy, and toluidine blue O assay, scanning electron microscopy, contact angle measurements for oil under water and thermogravimetry were used for characterizing the membranes and an assay of permeability was developed to quantify the diffusion of oil molecules across the electrospun membrane. The electrospun and/or decorated membranes showed an underwater oleophobic wettability, which can separate oil-in-water emulsions with 87% separation efficiency, results of fouling experiments, evaluated in terms of rejection and flux recovery ratio, exhibited good antifouling ability, but the membrane decoration process did not lead to superior outcomes compared with undecorated membranes.     

Performance modeling and analysis of message-oriented event-driven systems

Message-oriented event-driven systems are becoming increasingly ubiquitous in many industry domains including telecommunications, transportation and supply chain management. Applications in these areas typically have stringent requirements for performance and scalability. To guarantee adequate quality-of-service, systems must be subjected to a rigorous performance and scalability analysis before they are put into production. In this paper, we present a comprehensive modeling methodology for message-oriented event-driven systems in the context of a case study of a representative application in the supply chain management domain. The methodology, which is based on queueing Petri nets, provides a basis for performance analysis and capacity planning. We study a deployment of the SPECjms2007 standard benchmark on a leading commercial middleware platform. A detailed system model is built in a step-by-step fashion and then used to predict the system performance under various workload and configuration scenarios. After the case study, we present a set of generic performance modeling patterns that can be used as building blocks when modeling message-oriented event-driven systems. The results demonstrate the effectiveness, practicality and accuracy of the proposed modeling and prediction approach.     

GMAC: An overlay multicast network for mobile agent platforms

The lack of proper support for multicast services in the Internet has hindered the widespread use of applications that rely on group communication services such as mobile software agents. Although they do not require high bandwidth or heavy traffic, these types of applications need to cooperate in a scalable, fair and decentralized way. This paper presents GMAC, an overlay network that implements all multicast related functionality–including membership management and packet forwarding–in the end systems. GMAC introduces a new approach for providing multicast services for mobile agent platforms in a decentralized way, where group members cooperate in a fair way, minimize the protocol overhead, thus achieving great scalability. Simulations comparing GMAC with other approaches, in aspects such as end-to-end group propagation delay, group latency, group bandwidth, protocol overhead, resource utilization and failure recovery, show that GMAC is a scalable and robust solution to provide multicast services in a decentralized way to mobile software agent platforms with requirements similar to MoviLog.     

Building Illumination Coherent 3D Models of Large-Scale Outdoor Scenes

Systems for the creation of photorealistic models using range scans and digital photographs are becoming increasingly popular in a wide range of fields, from reverse engineering to cultural heritage preservation. These systems employ a range finder to acquire the geometry information and a digital camera to measure color detail. But bringing together a set of range scans and color images to produce an accurate and usable model is still an area of research with many unsolved problems. In this paper we address the problem of how to build illumination coherent integrated texture maps from images that were taken under different illumination conditions. To achieve this we present two different solutions. The first one is to align all the images to the same illumination, for which we have developed a technique that computes a relighting operator over the area of overlap of a pair of images that we then use to relight the entire image. Our proposed method can handle images with shadows and can effectively remove the shadows from the image, if required. The second technique uses the ratio of two images to factor out the diffuse reflectance of an image from its illumination. We do this without any light measuring device. By computing the actual reflectance we remove from the images any effects of the illumination, allowing us to create new renderings under novel illumination conditions.     

Linear quadratic gaussian optimization approach for signal-to-noise ratio constrained control over network

The research area of control over networks has attracted great interest in recent years. Inserted in this research area is the study of control feedback limitations imposed by the presence of a communication channel. In this paper we analyze the fundamental limitations in control feedback stabilizability imposed by a class of Signal-to-Noise Ratio (SNR) constrained communication channels. We solve the SNR constrained control over network problem as a linear quadratic Gaussian (LQG) optimization with loop transfer recovery (LTR). If the communication channel is located on the feedback path then the LTR is said to be performed at the output. Vice versa, if the communication channel is on the control path, then the recovery is said to be performed at the input. In the present paper we address both cases, namely the LQG optimization with LTR at the output and the LQG optimization with LTR at the input to solve an LTI SNR constrained problem. We then explore the link between these two solutions.     

SO(3) nonlinear σ model for a spiral phase in the spin-fermion model

Starting from a doped spin-fermion model for the CuO₂ planes in high-T_c superconductors, we derive an effective continuum theory for the spin degrees of freedom by means of a gradient expansion. We assume an incommmensurate, spiral configuration for the spins. Extending our previous treatment of a planar spiral, we allow for three-dimensional fluctuations of the spin fields, which are described by an S0(3) matrix order parameter. The continuum limit is obtained by a systematic expansion in powers of a short distance cutoff. The occurring infinite series is summed to all orders using a combinatorial method which exploits the constraint obeyed by the S0(3) order parameter. The resulting continuum theory is given by an S0(3) quantum nonlinear model, where the influence of doping is contained in the fermionic susceptibilities that enter into the coupling constants of the model.