Kinetic Basicities of Aqueous Binary Mixtures: A Surprisingly Good Linear Correlation with the Gas Phase Basicity of the Organic Cosolvent

A remarkably good correlation between the rate of proton transfer from excited protonated 1-aminopyrene and the gas phase basicities of the organic component in water: organic solvent binary mixtures has been found. We suggest that use of anilinium acids minimizes the effect of anion solvation and Coulomb interactions and enables the influence of the organic cosolvent on the proton transfer to be clearly observed. The model proposed is one in which the proton is always transferred to a water molecule and a concerted proton transfer to a water molecule solvated by the organic cosolvent also occurs. The cosolvent influence is then on this latter species via hydrogen bond interactions. The correlation holds in pure water but not in pure organic solvents where, clearly, the proton must be transferred to the organic molecule.     

Compiling OR-parallelism into AND-parallelism

This paper suggests a general method for compiling OR-parallelism into AND-parallelism. An interpreter for an AND/OR-parallel language written in the AND-parallel subset of the language induces a source-to-source transformation from the full language into the AND-parallel subset. This transformation can be identified and implemented as a special purpose compiler or applied using a general purpose partial evaluator. The method is demonstrated to compile a variant of Concurrent Prolog into an AND-parallel subset of the language called Flat Concurrent Prolog (FCP). It is also shown applicable to the compilation of OR-parallel Prolog to FCP. The transformation identified is simple and efficient. The performance of the method is discussed in the context of programming examples. These compare well with conventionally compiled Prolog programs.     

Fair,biased, and self-balancing merge operators: Their specification and implementation in Concurrent Prolog

The problem of allowing a dynamically changing set of processes fair access to a shared resource is considered, in the context of communication-stream based systems. It is argued that fair binary merge operators alone cannot solve this problem satisfactorily. Two solutions are proposed. One employs binary merge operators with a programmable bias; the other binary and ternary fair merge operators capable of self-balancing, using the concept of 2–3 trees. A Concurrent Prolog implementation of these operators is described. The implementation of the self-balancing merge operators illustrates the expressive power of incomplete messages, a programming technique that supports messages that contain communication channels as arguments. In the course of implementing the self-balancing merge operator, it was necessary to develop a distributed variant of the 2–3 tree deletion algorithm.     

Object oriented programming in Concurrent Prolog

It is shown that the basic operations of object-oriented programming languages — creating an, object, sending and receiving messages, modifying an object’s state, and forming class-superclass hierarchies — can be implemented naturally in Concurrent Prolog. In addition, a new object-oriented programming paradigm, called incomplete messages, is presented. This paradigm subsumes stream communication, and greatly simplifies the complexity of programs defining communication networks and protocols for managing shared resources. Several interesting programs are presented, including a multiple-window manager. All programs have been developed and tested using the Concurrent Prolog interpreter described in.¹⁾     

Fast geodesic active contours

We use an unconditionally stable numerical scheme to implement a fast version of the geodesic active contour model. The proposed scheme is useful for object segmentation in images, like tracking moving objects in a sequence of images. The method is based on the Weickert-Romeney-Viergever (additive operator splitting) AOS scheme. It is applied at small regions, motivated by the Adalsteinsson-Sethian level set narrow band approach, and uses Sethian's (1996) fast marching method for re-initialization. Experimental results demonstrate the power of the new method for tracking in color movies.     

The effect of polyethylene crystallinity and polarity on thermal stability and controlled release of essential oils in antimicrobial films

Antimicrobial packaging can preserve and increase shelf life of free preservatives food products. Active materials present in the packaging material can migrate, in a controlled manner, to the food surface, avoiding bacterial and fungal proliferation and keeping the food product edible for longer periods of time. Essential oils (EO) are natural antimicrobial agents that can be released to the headspace with no direct contact between the package and the food. To minimize loses of EO during high heat melt processing, a three stages process was implemented and tested. Antimicrobial films were prepared by melt mixing a variety of polyethylene copolymers in the presence of organo‐modified montmorillonite nano clay (NC) and thymol, an EO present in oregano and thyme. A controlled EO desorption from films can be achieved by changing the polymer crystallinity and polarity. As the crystallinity increased, the thermal stability of the EO during the extrusion process improved. The addition of NC affects the structure and homogeneity of the crystals. The combination of high polymer crystallinity and chemical affinity between EO and NC increased the thermal stability of the EO during film processing, enabling to control the desorption rate. The effect of multilayer structure based on varied densities and polarities was also studied. Increasing the polarity of the outer layers in multilayered film reduced the EO desorption rate as a result of chemical interactions between the polymer and the EO. The final antimicrobial activity of the films was also found to be dependent on the EO partitioning. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40309.     

Catalytic Formation of C−N Bonds: ICS Symposium Honoring Wolf Prize Laureates Stephen L. Buchwald and John F. Hartwig: May 29, 2019, Technion-Israel Institute of Technology,Haifa, Israel

This report covers two exciting events in the scientific landscape of the State of Israel: the traditional Wolf Prize Symposium of the ICS and the Wolf Prize Ceremony in the Knesset. The symposium, dedicated to the science of Stephen L. Buchwald and John F. Hartwig, highlighted the catalytic formation of C−N bonds. In a general sense, the two Wolf Prize laureates may be considered as molecular architects who produced efficient molecular-scale machines that make important molecules for the benefit of humanity. After receiving the Wolf Prize from Israel's President, Buchwald commented, “There are many who believe that support for research should focus exclusively on endeavors that have specific practical applications in mind. With this mindset, our work would have never been possible. Time and time again experience shows that it is exceedingly difficult to predict which scientific discoveries will lead to major advances. So often, it is the scientist following his or her own intellectual curiosity whose work leads to a breakthrough. I believe that basic curiosity-driven research and societal and economic progress are inextricably linked.” And Hartwig comments, “We all know the principles of science know no boundaries, but maybe less appreciated, or taken for granted, is that the assembly of research teams in many places knows no boundaries. If we recognize and nurture talent in people from all corners and all backgrounds we can address and maybe solve today's most important problems in health, energy, and environmental sustainability that are urgently facing us.”