Synthesis of biodegradable conjugated polymers with controlled backbone flexibility

A series of flexible, highly bright fluorescent poly(p‐phenyleneethynylene)s (PPEs) was prepared by employing a disulfide containing nonconjugated monomer at various ratios under Sonogashira reaction conditions. PPEs with flexible linkers exhibited fluorescence properties comparable to those of a fully conjugated PPE when less than 50% of flexible monomers were incorporated into the backbone. To evaluate the self‐assembly properties of PPEs, a series of conjugated polymer nanoparticles (CPNs) was fabricated by treating PPEs with organic acids followed by dialysis. CPNs containing linkers exhibited different complexation behavior with polysaccharides, warranting further investigation into how flexibility and biodegradability of CPNs influence their cellular interaction and entry. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1403–1412     

Cluster analysis of local convergent sequences of structures

The cluster analysis of very large objects is an important problem, which spans several theoretical as well as applied branches of mathematics and computer science. Here we suggest a novel approach: under assumption of local convergence of a sequence of finite structures we derive an asymptotic clustering. This is achieved by a blend of analytic and geometric techniques, and particularly by a new interpretation of the authors' representation theorem for limits of local convergent sequences, which serves as a guidance for the whole process. Our study may be seen as an effort to describe connectivity structure at the limit (without having a defined explicit limit structure) and to pull this connectivity structure back to the finite structures in the sequence in a continuous way. © 2017 Wiley Periodicals, Inc. Random Struct. Alg., 51, 674–728, 2017     

Limits of structures and the example of tree semi-lattices

The notion of left convergent sequences of graphs introduced by Lovász et al. (in relation with homomorphism densities for fixed patterns and Szemerédi’s regularity lemma) got increasingly studied over the past $10$ years. Recently, Ne?et?il and Ossona de Mendez introduced a general framework for convergence of sequences of structures. In particular, the authors introduced the notion of $QF$-convergence, which is a natural generalization of left-convergence. In this paper, we initiate study of $QF$-convergence for structures with functional symbols by focusing on the particular case of tree semi-lattices. We fully characterize the limit objects and give an application to the study of left convergence of $m$-partite cographs, a generalization of cographs.     

Development of headspace SPME method for analysis of volatile organic compounds present in human biological specimens

In recent years, interest has increased regarding the identification of volatile organic compounds (VOCs) for metabolic profiling, human scent identification of the living and deceased, and diagnostic potentials for certain diseases that are known for its association with distinct odor. In this study, a method has been developed that is capable of sampling, identifying, and differentiating the VOCs present in various biological specimens of forensic importance (blood, breath, buccal cells, and urine) taken from the same individuals. The developed method requires a pretreatment step to remove targeted VOCs from the sampling apparatus prior to sampling of the individual specimens. The VOCs collected from the biological specimens were characterized by solid-phase microextraction and gas chromatography/mass spectrometry with ratios of the most abundant and frequent VOCs compared using qualitative and semiquantitative methods. Blood, breath, and buccal cells required extraction procedures ranging from 18 to 21 h in order to optimize the limit of detection, which averaged 5–15 ng across these specimens. The optimal method for measuring urine VOCs was complete in less than an hour; however, the limit of detection was higher with a range of 10–40 ng quantifiable. The demonstrated sensitivity and reproducibility of the methods developed allow for population studies of human scent VOCs from various biological specimen collection kits used in the forensic and clinical fields.     

Conjugated polymer nanoparticles for small interfering RNA delivery

Loosely aggregated conjugated polymer nanoparticles (CPNs) were used as nontoxic and efficient small interfering RNA (siRNA) delivery vehicles with delivery visualization. A significant down regulation (94%) of a target gene was achieved by transfection of HeLa cells with the CPNs/siRNA complexes, supporting CPN as a promising siRNA delivery carrier.     

Nanoparticle Size and Concentration Dependence of the Electroactive Phase Content and Electrical and Optical Properties of Ag/Poly(vinylidene fluoride) Composites

This paper describes the processing of silver‐nanoparticle‐doped poly(vinylidene fluoride). The effects of the concentration and size of the filler on the electroactive phase of the polymer and the optical and electrical properties are discussed. Spherical silver nanoparticles incorporated into the poly(vinylidene fluoride) polymeric matrix induce nucleation of the electroactive γ phase. The electroactive phase content strongly depends on the content and size of the nanoparticles. In particular, there is a critical nanoparticle size, below which the filler losses its nucleation efficiency due to its small size relative to that of the polymer macromolecules. Furthermore, the presence of surface plasmon resonance absorption in the composites is observed, which once again shows a strong dependence on the concentration and size of the particles. The absorption is larger for higher concentrations, and for a given concentration increases with particle size. This behavior is correlated to the electrical response and is related to the extra bands and electrons provided by the nanoparticles in the large energy band gap of the polymer.     

Approximate analytic solutions to Radulet equations for the analysis of electromagnetic transients in single-phase power transmission lines

In this work, an analytic development for a transmission line with a corona effect for simulating an electromagnetic transient is presented. The asymptotic solution for the Radulet equations in which a nonlinear term is presented is obtained. The study is carried out for a single-phase transmission line. The electrical parameters for an overhead line are defined and several formulations for their calculation are presented. The frequency dependence of the electrical parameters is considered. In the first part, the linear problem solution is found; the Fourier and Laplace transforms are applied with respect to distance and time respectively. After finding the solution in the Fourier–Laplace domain, which is expressed in terms of a Green’s function integral, an approximate analytical solution is obtained in the distance–time domain by means of asymptotic methods. Finally, the nonlinear solution is found using as a first approach the linear solution. The results obtained show an attenuation in the voltage wave due to the corona effect.     

Formulations of the 3+1 evolution equations in curvilinear coordinates

Following Brown (Phys Rev D79:104029, 2009), in this paper we give an overview of how to modify standard hyperbolic formulations of the 3+1 evolution equations of General Relativity in such a way that all auxiliary quantities are true tensors, thus allowing for these formulations to be used with curvilinear sets of coordinates such as spherical or cylindrical coordinates. After considering the general case for both the Nagy–Ortiz–Reula and the Baumgarte–Shapiro–Shibata–Nakamura (BSSN) formulations, we specialize to the case of spherical symmetry and also discuss the issue of regularity at the origin. Finally, we show some numerical examples of the modified BSSN formulation at work in spherical symmetry.     

Precision determination of the D0 mass

A precision measurement of the D0 meson mass has been made using approximately 281 pb(-1) of e+e- annihilation data taken with the CLEO-c detector at the psi(3770) resonance. The exclusive decay D0-->K_{S}phi has been used to obtain M(D0)=1864.847+/-0.150(stat)+/-0.095(syst) MeV. This corresponds to M(D0D*0)=3871.81+/-0.36 MeV, and leads to a well-constrained determination of the binding energy of the proposed D0D*0 molecule X(3872), as Eb=0.6+/-0.6 MeV.