Novel Synthesis and Characterization of Doxycycline‐Loaded Gold Nanoparticles: The Golden Doxycycline for Antibacterial Applications

Doxycycline (DOXY) is a tetracycline antibiotic with a potent antibacterial activity against a wide variety of bacteria. One potential strategy to enhance the penetration and the antibacterial activity of antibiotics is the use of nanotechnology. In this work, an innovative synthesis of stable PEGylated‐gold nanoparticles (PEG‐AuNPs) loaded with DOXY is reported. As far as it is known, this is the first report on the combination of DOXY with AuNPs as polymeric complex. The obtained nanoparticles are fully characterized by transmission electron microscopy, dynamic light scattering, zeta‐potential, and UV–vis and Raman spectroscopy. The stability and sustained activity of the drug in nanoparticles is determined on a panel of Gram‐positive and Gram‐negative bacteria in comparison with the native form of the drug. This combined therapeutic agent restores the susceptibility of DOXY and shows an antibacterial activity against major human pathogens.     

Single drop microextraction—Development,applications and future trends

Single drop microextraction (SDME) has emerged over the last 10–15 years as one of the simplest and most easily implemented forms of micro-scale sample cleanup and preconcentration. In the most common arrangement, an ordinary chromatography syringe is used to suspend microliter quantities of extracting solvent either directly immersed in the sample, or in the headspace above the sample. The same syringe is then used to introduce the solvent and extracted analytes into the chromatography system for identification and/or quantitation. This review article summarizes the historical development and various modes of the technique, some theoretical and practical aspects, recent trends and selected applications.     

Ascending Runs in Dependent Uniformly Distributed Random Variables: Application to Wireless Networks

We analyze in this paper the longest increasing contiguous sequence or maximal ascending run of random variables with common uniform distribution but not independent. Their dependence is characterized by the fact that two successive random variables cannot take the same value. Using a Markov chain approach, we study the distribution of the maximal ascending run and we develop an algorithm to compute it. This problem comes from the analysis of several self-organizing protocols designed for large-scale wireless sensor networks, and we show how our results apply to this domain.     

Syntheses and NLO properties of metal alkynyl dendrimers

Metal-containing (particularly organometallic) dendrimers are briefly introduced, the origin of nonlinear optical (NLO) effects in molecules is briefly summarized, and the syntheses of metal alkynyl dendrimers and progress in employing metal alkynyl dendrimers as NLO materials are reviewed.     

Quantitative microarray profiling of DNA-binding molecules

A high-throughput Cognate Site Identity (CSI) microarray platform interrogating all 524 800 10-base pair variable sites is correlated to quantitative DNase I footprinting data of DNA binding pyrrole-imidazole polyamides. An eight-ring hairpin polyamide programmed to target the 5 bp sequence 5'-TACGT-3' within the hypoxia response element (HRE) yielded a CSI microarray-derived sequence motif of 5'-WWACGT-3' (W = A,T). A linear beta-linked polyamide programmed to target a (GAA)3 repeat yielded a CSI microarray-derived sequence motif of 5'-AARAARWWG-3' (R = G,A). Quantitative DNase I footprinting of selected sequences from each microarray experiment enabled quantitative prediction of Ka values across the microarray intensity spectrum.     

Continuous-time, stage-structured, multiple-species model with applications to amphibians

Since the 1980s, biologists have noticed a major decline in amphibian population. The reason this is so alarming is because amphibians have been seen as a “Canary in the mine” when it comes to the world’s environmental changes. With global warming and CO₂ emissions all over the news, we have become more aware of how we are impacting our world. If the decline of amphibians is a precursor to what is happening with the environment, then we need to find a good model to give us estimates on what is going to happen in the future. Here we used a predator-prey-competition model to help investigate how three amphibians might interact when confined to the same area.     

Empirical Polygon Simulation and Central Limit Theorems for the Homogenous Poisson Line Process

For the Poisson line process the empirical polygon is defined thanks to ergodicity and laws of large numbers for some characteristics, such as the number of edges, the perimeter, the area, etc... One also has, still thanks to the ergodicity of the Poisson line process, a canonical relation between this empirical polygon and the polygon containing a given point. The aim of this paper is to provide numerical simulations for both methods: in a previous paper (Paroux, Advances in Applied Probability, 30:640–656, 1998) one of the authors proved central limit theorems for some geometrical quantities associated with this empirical Poisson polygon, we provide numerical simulations for this phenomenon which generates billions of polygons at a small computational cost. We also give another direct simulation of the polygon containing the origin, which enables us to give further values for empirical moments of some geometrical quantities than the ones that were known or computed in the litterature. This work was partially supported by the PSMN at ENS-Lyon.     

Understanding the preferential adsorption of CO2 over N2 in a flexible metal-organic framework

The unusual uptake behavior and preferential adsorption of CO(2) over N(2) are investigated in a flexible metal-organic framework system, Zn(2)(bdc)(2)(bpee), where bpdc = 4,4'-biphenyl dicarboxylate and bpee = 1,2-bis(4-pyridyl)ethylene, using Raman and IR spectroscopy. The results indicate that the interaction of CO(2) with the framework induces a twisting of one of its ligands, which is possible because of the type of connectivity of the carboxylate end group of the ligand to the metal center and the specific interaction of CO(2) with the framework. The flexibility of the bpee pillars allows the structure to respond to the twisting, fostering the adsorption of more CO(2). DFT calculations support the qualitative picture derived from the experimental analysis. The adsorption sites at higher loading have been identified using a modified van der Waals-Density Functional Theory method, showing that the more energetically favorable positions for the CO(2) molecules are closer to the C═C bond of the bpee and the C-C bond of the bpdc ligands instead of the benzene and pyridine rings of these ligands. These findings are consistent with changes observed using Raman spectroscopy, which is useful for detecting both specific guest-host interactions and structural changes in the framework.