Simple Coupling Research Articles

Uniform Contractivity in Wasserstein Metric for the Original 1D Kac’s Model

We study here a very popular 1D jump model introduced by Kac: it consists of $N$ velocities encountering random binary collisions at which they randomly exchange energy. We show the uniform (in $N$) exponential contractivity of the dynamics in a non-standard Monge-Kantorovich-Wasserstein: precisely the MKW metric of order 2 on the energy. The result is optimal in the sense that for each $N$, the contractivity constant is equal to the $L^2$ spectral gap of the generator associated to Kac's dynamic. As a corollary, we get an uniform but non optimal contractivity in the MKW metric of order $4$. We use a simple coupling that works better that the parallel one. The estimates are simple and new (to the best of our knowledge).

An integrative toy model of cell flattening, spreading, and ruffling.

The processes of cell spreading and crawling are frequently associated with mysterious waves and ruffling cycles of the leading edge. To develop a physical model that can account for these phenomena based on a few simple and plausible rules governing adhesion, contractility, polymerization of cytoskeleton, and membrane tension. Extension of a continuum mechanical model of phagocytosis [J Cell Sci. (2006);119(Pt 9):1903-13] adding a simple coupling between membrane curvature and cytoskeletal polymerization. We show that our generalized model has just the right nonlinearity needed for triggering of stochastic/chaotic cycles of ruffling similar to those that are observed in real cells. The cycles are caused by a branching instability at the leading edge that leads to bifurcations of protrusion into forward moving lamellipodium and upward and rearward folding ruffles. The amplitude of the instability is modulated by the surface tension, with higher tension stabilizing against ruffling (but inhibiting protrusion) and lower tension promoting ruffling and protrusion.

Transition metal-free intramolecular regioselective couplings of aliphatic and aromatic C-H bonds.

Cross-dehydrogenative couplings of two different C-H bonds have emerged as an attractive goal in organic synthesis. However, achieving regioselective C-H activation is a great challenge because C-H bonds are ubiquitous in organic compounds. Actually, the regioselective couplings promoted by enzymes are a common occurrence in nature. Herein, we have developed simple, efficient and general transition metal-free intramolecular couplings of alphatic and aromatic C-H bonds. The protocol uses readily available aryl triazene as the radical initiator, cheap K2S2O8 as the oxidant, and the couplings were performed well with excellent tolerance of functional groups. Interestingly, α-carbon configuration of some amino acid residues in the substrates was kept after the reactions, and the couplings for substrates with substituted phenylalanine residues exhibited complete β-carbon diastereoselectivity for induction of the chiral α-carbon. Therefore, the present study should provide a novel strategy for regioselective cross-dehydrogenative couplings of two different C-H bonds.

Nonlinear Excitation of Subcritical Instabilities in a Toroidal Plasma.

In a collisionless plasma, it is known that linearly stable modes can be destabilized (subcritically) by the presence of structures in phase space. However, nonlinear growth requires the presence of a seed structure with a relatively large threshold in amplitude. We demonstrate that, in the presence of another, linearly unstable (supercritical) mode, wave-wave coupling can provide a seed, which is significantly below the threshold, but can still grow by (and only by) the collaboration of fluid and kinetic nonlinearities. By modeling the subcritical mode kinetically, and the impact of the supercritical mode by simple wave-wave coupling equations, it is shown that this new kind of subcritical instability can be triggered, even when the frequency of the supercritical mode is rapidly sweeping. The model is applied to the bursty onset of geodesic acoustic modes in a LHD experiment. The model recovers several key features such as relative amplitude, time scales, and phase relations. It suggests that the strongest bursts are subcritical instabilities, driven by this mechanism of combined fluid and kinetic nonlinearities.

Polymer grafted magnetic nanoparticles for delivery of anticancer drug at lower pH and elevated temperature

Efficient and controlled delivery of therapeutics to tumor cells is one of the important issues in cancer therapy. In the present work, a series of pH- and temperature-responsive polymer grafted iron oxide nanoparticles were prepared by simple coupling of aminated iron oxide nanoparticle with poly(N-isopropylacrylamide-ran-poly(ethylene glycol) methyl ether acrylate)-block-poly(acrylic acid) (P(NIPA-r-PEGMEA)-b-PAA). For this, three water soluble block polymers were prepared via reversible addition fragmentation transfer (RAFT) polymerization technique. At first, three different block copolymers were prepared by polymerizing mixture of NIPA and PEGMEA (with varying mole ratio) in presence of poly(tert-butyl acrylate) (PtBA) macro chain transfer agent. Subsequently, P(NIPA-r-PEGMEA)-b-PAA copolymers were synthesized by hydrolyzing tert-butyl acrylate groups of the P(NIPA-r-PEGMEA)-b-PtBA copolymers. The resulting polymers were then grafted to iron oxide nanoparticles, and these functionalized nanoparticles were thoroughly characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), zeta potential measurements, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), vibrating sample magnetometer (VSM) and Fourier transform infrared spectroscopy (FTIR). Doxorubicin (DOX), an anti-cancer drug, was loaded into the polymer coated nanoparticles and its release behavior was subsequently studied at different pH and temperatures. The drug release pattern revealed a sustained release of DOX preferentially at the desired lysosomal pH of cancer cells (pH 5.0) and slightly above the physiological temperature depending upon the composition of the copolymers. The potential anticancer activity of the polymer grafted DOX loaded nanoparticles were established by MTT assay and apoptosis study of cervical cancer ME 180cells in presence of the nanoparticles. Thus, these particles can be utilized for controlled delivery of anticancer drugs at the desired lysosomal pH and/or by slightly heating the cells using magnetic hyperthermia.

On the Phase Coupling of Two Components Mixing in Empirical Mode Decomposition

This paper investigates frequency mixing effect of empirical mode decomposition (EMD) and explores whether it can be explained by simple phase coupling between components of the input signal. The input is assumed to be a linear combination of harmonic oscillators. The hypothesis was tested assuming that phases of input signals’ components would couple according to Kuramoto’s model. Using a Kuramoto’s model with as many oscillators as the number of intrinsic mode functions (result of EMD), the model’s parameters were adjusted by a particle swarm optimization (PSO) method. The results show that our hypothesis is plausible, however, a different coupling mechanism than the simple sine-coupling Kuramoto’s model are likely to give better results.

Preserving the adhesion of catechol-conjugated hydrogels by thiourea-quinone coupling.

Mussel adhesion has inspired the development of catechol-based adhesive polymers. However, conventional strategies require basic pH conditions and lead to the loss of adhesion. To solve the problem, we report the first attempt to use thiourea-functionalized polymers for preserving hydrogel adhesion. We believe that this simple thiourea-quinone coupling chemistry is instrumental to synthetic adhesive materials.

Dispersive liquid–liquid microextraction coupled with single-drop microextraction for the fast determination of sulfonamides in environmental water samples by high performance liquid chromatography-ultraviolet detection

A simple coupling of low-density solvent-based solvent-demulsification dispersive liquid–liquid microextraction (2-min pre-extraction) and single-drop microextraction (15-min back-extraction).

Enhancements in ElectroKinetic Remediation Technology: Environmental assessment in comparison with other configurations and consolidated solutions

The extraction of contaminants from an earthy matrix using the ElectroKinetic Remediation Technology (EKRT) requires suitable electric fields to be applied through the soil. In some cases, the further addition of appropriate chemicals helps the dissolution and thus the removal of the pollutants.EKRT has the potential to achieve results similar to other on-site and/or off-site interventions, but with substantially higher levels of acceptability, thus representing a very interesting approach in dealing with contamination by heavy metals. However, due to the use of consumable materials and basically high energy consumption, this technology can heavily impact on the environment, if non appropriately configured.In this study, the electrokinetic approach for the remediation of a multi-metal contaminated real site in terms of environmental assessment has been investigated by using the GaBi LCA software, to demonstrate that, in spite of expectation, a suitable system configuration can make this technology an excellent choice also in terms of environmental sustainability. The environmental assessment was conducted in terms of Global Warming Potential (GWP-100years): the proposed technology has been compared with a different EKRT configuration taken from the literature, and the environmental impact evaluated against that of a conventional treatment, i.e. the excavation and disposal of contaminated soil in landfill. Despite the different configuration, the results show the advantages of the EKRT and in particular, how the specific improvements introduced are effective for reducing the ecological footprint. Moreover, having decreased the impacts related to the installation of the system above all, its simple coupling with alternative solutions for the production of energy could further increase the advantages of the approach, bringing the intervention to very high levels of environmental sustainability.

Controlling the Architecture, Coordination, and Reactivity of Nanoparticle Coating Utilizing an Amino Acid Central Scaffold.

We have developed a versatile strategy to prepare a series of multicoordinating and multifunctional ligands optimized for the surface-functionalization of luminescent quantum dots (QDs) and gold nanoparticles (AuNPs) alike. Our chemical design relies on the modification of l-aspartic acid precursor to controllably combine, through simple peptide coupling chemistry, one or two lipoic acid (LA) groups and poly(ethylene glycol) (PEG) moieties in the same ligand. This route has provided two sets of modular ligands: (i) bis(LA)-PEG, which presents two lipoic acids (higher coordination) appended onto a single end-functionalized PEG, and (ii) LA-(PEG)2 made of two PEG moieties (higher branching, with various end reactive groups) appended onto a single lipoic acid. These ligands are combined with a new photoligation strategy to yield hydrophilic and reactive QDs that are colloidally stable over a broad range of conditions, including storage at nanomolar concentration and under ambient conditions. AuNPs capped with these ligands exhibit excellent stability in various biological conditions and improved resistance against NaCN digestion. This route also provides compact nanocrystals with tunable surface reactivity. As such, we have covalently coupled QDs capped with bis(LA)-PEG-COOH to transferrin to facilitate intracellular uptake. We have also characterized and quantified the coupling of dye-labeled peptides to QD surfaces using fluorescence resonance energy transfer interactions in QD-peptide-dye assemblies.

Abstract 15031: Defining a Coupling Ratio: Tissue Doppler Velocities in Systole and Diastole Predict Greater Diastolic Than Systolic Impairment in Hypertrophic Cardiomyopathy

Introduction: Mitral annular velocities, E’ and S’, (cm/s) measured by Tissue Doppler Imaging, are used in clinical cardiology and in research as important descriptors of systolic and diastolic function. We hypothesized that the relationship between these velocities in normal individuals would be linear, and would define a ventricular systolic/diastolic coupling ratio. We further hypothesized that departure from this normal coupling ratio might provide insight into certain disease states. Methods: We reviewed consecutive ECHOs performed at our institution to define the coupling ratio in normal individuals (n=57) and in 2 disease states dilated cardiomyopathy (DCM) (n=20), and hypertrophic cardiomyopathy (HCM) (n=19). The average of peak septal and lateral velocities, obtained in systole and diastole were compared (ANOVA). Results: Baseline characters as depicted in the table. In normals, there is a linear relationship between S’ and E’. While the S’ and E’ velocities are lower in absolute terms in DCM, the coupling ratio is similar to that seen in Normals. HCM, by contrast shows a relatively lower coupling ratio than Normals or DCM (Figure attached). Conclusion: We have defined a simple coupling ratio of systolic and diastolic velocities in normal and cardiomyopathy. The greater relative impairment on diastolic velocities in HCM appears to reflect a greater relative impairment in diastolic filling than in systolic shortening. In other words, for a given degree of systolic fiber shortening, fiber lengthening/stretch and perhaps utilization of the Frank Starling mechanism would be disproportionately impaired.

Multimodal vibration damping of a beam with a periodic array of piezoelectric patches connected to a passive electrical network

A multimodal damping strategy is implemented by coupling a beam to its analogue electrical network. This network comes from the direct electromechanical analogy applied to a transverse lattice of point masses that represents the discrete model of a beam. The mechanical and electrical structures are connected together through an array of piezoelectric patches. A discrete and a semi-continuous model are proposed to describe the piezoelectric coupling. Both are based on the transfer matrix formulation and consider a finite number of patches. It is shown that a simple coupling condition gives a network that approximates the modal properties of the beam. A multimodal tuned mass effect is then obtained and a wide-band damping is introduced by choosing a suitable positioning for resistors in the network. The strategy and the models are experimentally validated by coupling a free-free beam to a completely passive network. A multimodal vibration reduction is observed, which proves the efficiency of the control solution and its potential in term of practical implementation.

The superexchange interactions and magnetic ordering in low-dimentional ludwigite Ni5GeB2O10

The ludwigite Ni5Ge(BO5)2 belongs to a family of oxyborates which have low-dimensional subunits in the form of three-leg ladders unit structure. This material was studied by magnetic and thermodynamic measurements. Ni5Ge(BO5)2 does not show full long-range magnetic order, but one goes into a partial ordering or spin-glass state at 87K. The superexchange interactions were calculated in the framework of a simple indirect coupling model. Different models of magnetic structure of Ni5Ge(BO5)2 and its unique magnetic behaviour was discussed.

Manganese-Mediated Coupling Reaction of Vinylarenes and Aliphatic Alcohols.

Alcohols and alkenes are the most abundant and commonly used organic building blocks in the large-scale chemical synthesis. Herein, this is the first time to report a novel and operationally simple coupling reaction of vinylarenes and aliphatic alcohols catalyzed by manganese in the presence of TBHP (tert-butyl hydroperoxide). This coupling reaction provides the oxyalkylated products of vinylarenes with good regioselectivity and accomplishes with the principles of step-economies. A possible reaction mechanism has also been proposed.

Quantum field theory of relic nonequilibrium systems

In terms of the de Broglie-Bohm pilot-wave formulation of quantum theory, we develop field-theoretical models of quantum nonequilibrium systems which could exist today as relics from the very early universe. We consider relic excited states generated by inflaton decay, as well as relic vacuum modes, for particle species that decoupled close to the Planck temperature. Simple estimates suggest that, at least in principle, quantum nonequilibrium could survive to the present day for some relic systems. The main focus of this paper is to describe the behaviour of such systems in terms of field theory, with the aim of understanding how relic quantum nonequilibrium might manifest experimentally. We show by explicit calculation that simple perturbative couplings will transfer quantum nonequilibrium from one field to another (for example from the inflaton field to its decay products). We also show that fields in a state of quantum nonequilibrium will generate anomalous spectra for standard energy measurements. Possible connections to current astrophysical observations are briefly addressed.

ChemInform Abstract: Simple and Expeditious Pinacol Coupling of Non Usual α,β‐Unsaturated Carbonyl Compounds in Water.

Abstractusing zinc as cheap and readily available reductant

An efficient method to functionalize soybean protein fiber for fuse wire application

An etchant-free surface pre-treatment process for the preparation of copper/soybean protein fiber (Cu/SPF) via electroless plating was studied. A tight, dense and continuous structure of copper coating was obtained in this process. 3-Aminopropyltrimethoxysilane molecule was successfully grafted onto the SPF via a simple coupling reaction. In addition, Au, Ag or Pd nanoparticles were immobilized on the SPF substrate as catalyst sites for electroless plating. All the copper coatings via different metal activation were firmly adhered to the SPF substrate, as determined by an adhesive scotch®-tape test. The measurement of the electrothermal property of the Cu/SPF composites was carried out by a home-made direct current circuit. The composite from Ag activation process held a relatively higher rated current and a lower melting point, which indicated that it was more suitable to be made as the fuse wire than the composites from Au or Pd activation process.

From lattice gauge theories to hydrogen atoms

We construct canonical transformations to obtain a complete and most economical realization of the physical Hilbert space Hp of pure SU(2)2+1 lattice gauge theory in terms of Wigner coupled Hilbert spaces of hydrogen atoms. One hydrogen atom is assigned to every plaquette of the lattice. A complete orthonormal description of the Wilson loop basis in Hp is obtained by all possible angular momentum Wigner couplings of hydrogen atom energy eigenstates |n l m〉 describing electric fluxes on the loops. The SU(2) gauge invariance implies that the total angular momenta of all hydrogen atoms vanish. The canonical transformations also enable us to rewrite the Kogut–Susskind Hamiltonian in terms of fundamental Wilson loop operators and their conjugate electric fields. The resulting loop Hamiltonian has a global SU(2) invariance and a simple weak coupling (g2→0) continuum limit. The canonical transformations leading to the loop Hamiltonian are valid for any SU(N). The ideas and techniques can also be extended to higher dimension.

ChemInform Abstract: Nickel‐Catalyzed Reductive Heck Type Coupling of Saturated Alkyl Halides with Acrylates and Oxabenzonorbornadiene.

The Heck reaction is a well-established transition-metal catalyzed reaction for coupling alkenes with sp2 alkyl halides to give novel unsaturated compounds. Herein we report an analogous Heck-inspired, simple efficient coupling of sp3 alkyl halides with electron-withdrawing alkenes to form reductive coupling products where saturated esters are obtained. A range of acrylates were coupled with sp3 alkyl halides in the presence of Ni(PPh3)2Cl2 catalyst, Zn metal powder, CH3CN solvent, and water, at 80 °C to form the reductive Heck type saturated ester products in good yields. This strategy was further extended to couple oxabenzonorbornadiene with the alkyl halides resulting in ring opening to give rise to bicyclic alcohol products. The mechanism for both the reactions appears to be the usual oxidative-addition driven alkene insertion reaction where the water appears to act as the protonating agent.

Transport- and surface reaction-controlled SON68 glass dissolution at 30 °C and 70 °C and pH = 13.7

We report the modelling and experimental studies of SON68 glass dissolution in hyperalkaline solution (pH=13.7) at 30 and 70°C for more than 300days. In the experiments at 30°C and the first 100days at 70°C, the concentrations of B, Mo, alkalis and even Si showed square root of time dependence indicative of a diffusion-controlled process. At 70°C fast dissolution resumed after about 100days due to crystallization of aluminosilicates, and glass dissolution became surface reaction-controlled. For the experiment at 30°C, a simple model coupling dissolution of the glass and precipitation of secondary phases can also produce a good result for non-conservative elements, such as Ca and Al.