Thiol-Functionalized Palladium Nanoparticles Networks: Synthesis,Characterization, and Room Temperature (Toxic) Vapor Detection

The preparation of three different functionalized palladium nanoparticles (PdNPs) systems for room temperature BTX (benzene, toluene, p-xylene) sensing detection and their morphostructural characterization is described. PdNPs are prepared through a two-phase water/toluene wet chemical reduction method in the presence of bifunctional organic thiols as stabilizing agents suitable for the formation of covalently linked PdNPs networks: p-terphenyl-4,4″-dithiol (PdNPs-TR), biphenyl-4,4′-dithiol (PdNPs-BP), or with 9,9-didodecyl-2,7-bis(acetylthio)fluorene (PdNPs-FL). Comparing the hydrodynamic diameter values, TR and BP ligands help to obtain networks consisting of spherical NPs of about 2 nm, in which each bifunctional ligand act as a bridge between PdNPs. In contrast, PdNPs-FL show a population centered at <2R_H> = 45 ± 5 nm. To perform preliminary gas sensing measurements, PdNPs networks are cast deposited on interdigitated electrodes to study their resistive response toward volatile organic compounds (VOCs) such as benzene (0–5%), toluene (0–1.7%), and p-xylene (0–0.4%) (BTX) and common interfering gases (H₂S, NH₃, SO₂, and relative humidity, RH). PdNPs-FL show enhanced response to BTX with an appreciable response also toward H₂S and RH. PdNPs-TR exhibit a better ability to discriminate benzene gas with a negligible response after H₂S exposure. Moreover, all the PdNPs systems show little to no response to NH₃ and SO₂ gases, offering an interesting perspective in practical sensing applications.     

Quantum state-resolved probing of strong-field-ionized xenon atoms using femtosecond high-order harmonic transient absorption spectroscopy

Femtosecond high-order harmonic transient absorption spectroscopy is used to resolve the complete |j,m quantum state distribution of Xe+ produced by optical strong-field ionization of Xe atoms at 800 nm. Probing at the Xe N4/5 edge yields a population distribution rhoj,|m| of rho3/2,1/2ratiorho1/2,1/2ratiorho3/2,3/2=75+/-6 :12+/-3 :13+/-6%. The result is compared to a tunnel ionization calculation with the inclusion of spin-orbit coupling, revealing nonadiabatic ionization behavior. The sub-50-fs time resolution paves the way for tabletop extreme ultraviolet absorption probing of ultrafast dynamics.     

Ratiometric photoacoustic sensing of pH using a "sonophore"

This work describes ratiometric photoacoustic chemical sensing of pH, and describes how these measurements can be applied as a ratiometric biomedical imaging modality to image pH in intact biological tissue.     

Newtonian law with memory

In this study we analyzed the Newtonian equation with memory. One physical model possessing memory effect is analyzed in detail. The fractional generalization of this model is investigated and the exact solutions within Caputo and Riemann–Liouville fractional derivatives are reported.     

Desorption chemical ionization tandem mass spectrometry of polyprenyl and dolichyl phosphates

Negative-ion desorption chemical ionization (DCI) tandem mass spectrometry was applied to the analysis of nanomole quantities of semisynthetic polyisoprenyl phosphates, the chain length of which ranged from 7 to 20 isoprene units. The DCI spectrum of all the compounds tested show the presence of independently generated ions [M-HPO₃-H]^?, [M-H₃PO₂-H]^? and [M-H₃PO₄-H]^? resulting from the loss of a part of or the entire phosphate group of a polyisoprenyl-P. In tandem mass spectrometry, the [M-H₃PO₄-H]^? fragment produces series of ions 68 mass units apart, indicative of the polyisoprenoid nature of a compound. Studies with deuterated and α-saturated polyisoprenyl phosphates demonstrated that fragmentations of the [M-H₃PO₄-H]^? ion proceed from both ends (α and ω) of a polyisoprenoid chain and may occur at either allylic (A) or vinylic (V) sites. Fragments of masses equal to [n×68 ? 1] and [n×68 ? 13] (where n is the number of isoprene units and 3≤n is less than the total number of isoprene residues within a polyisoprenoid chain) comprise the αA and ωV series, respectively, and represent the most abundant ions in tandem mass spectra of the [M-H₃PO₄-H]^? fragment of polyprenyl phosphates, α-Saturated dolichyl phosphates can be distinguished easily from corresponding polyprenyl phosphates not only on the basis of a 2-u shift of the [M-H₃PO₄-H]^? ion and the α series of fragments, but also because of the presence of an additional (A+14) series of ions 14 u heavier than fragments resulting from the allylic cleavages of an α-saturated polyisoprenoid chain. Possible mechanisms of the collision-induced dissociation reactions of polyprenyl phosphates are discussed.     

Clustering properties,Jack polynomials and unitary conformal field theories

Recently, Jack polynomials have been proposed as natural generalizations of Zk${\mathbb{Z}}_k$ Read–Rezayi states describing non-Abelian fractional quantum Hall systems. These polynomials are conjectured to be related to correlation functions of a class of W-conformal field theories based on the Lie algebra A_k−1$A_{k-1}$. These theories can be considered as non-unitary solutions of a more general series of CFTs with Zk${\mathbb{Z}}_k$ symmetry, the parafermionic theories. Starting from the observation that some parafermionic theories admit unitary solutions as well, we show, by computing the corresponding correlation functions, that these theories provide trial wavefunctions which satisfy the same clustering properties as the non-unitary ones. We show explicitly that, although the wavefunctions constructed by unitary CFTs cannot be expressed as a single Jack polynomial, they still show a fine structure where the mathematical properties of the Jack polynomials play a major role.     

A Model for Coagulation with Mating

We consider in this work a model for aggregation, where the coalescing particles initially have a certain number of potential links (called arms) which are used to perform coagulations. There are two types of arms, male and female, and two particles may coagulate only if one has an available male arm, and the other has an available female arm. After a coagulation, the used arms are no longer available. We are interested in the concentrations of the different types of particles, which are governed by a modification of Smoluchowski’s coagulation equation—that is, an infinite system of nonlinear differential equations. Using generating functions and solving a nonlinear PDE, we show that, up to some critical time, there is a unique solution to this equation. The Lagrange Inversion Formula allows in some cases to obtain explicit solutions, and to relate our model to two recent models for limited aggregation. We also show that, whenever the critical time is infinite, the concentrations converge to a state where all arms have disappeared, and the distribution of the masses is related to the law of the size of some two-type Galton-Watson tree. Finally, we consider a microscopic model for coagulation: we construct a sequence of Marcus-Lushnikov processes, and show that it converges, before the critical time, to the solution of our modified Smoluchowski’s equation.     

Molecular,Macromolecular, and Supramolecular Glucuronide Prodrugs: Lead Identified for Anticancer Prodrug Monotherapy

In this work, a tumor growth intervention by localized drug synthesis within the tumor volume, using the enzymatic repertoire of the tumor itself, is presented. Towards the overall success, molecular, macromolecular, and supramolecular glucuronide prodrugs were designed for a highly potent toxin, monomethyl auristatin E (MMAE). The lead candidate exhibited a fold difference in toxicity between the prodrug and the drug of 175, had an engineered mechanism to enhance the deliverable payload to tumours, and contained a highly potent toxin such that bioconversion of only a few prodrug molecules created a concentration of MMAE sufficient enough for efficient suppression of tumor growth. Each of these points is highly significant and together afford a safe, selective anticancer measure, making tumor‐targeted glucuronides attractive for translational medicine.     

Raman spectroscopy: a tool for biomechanical characterization of Stratum Corneum

The mechanical properties of the Stratum Corneum (SC) have been studied by different authors at the macroscopic level, but the modification of its ultra structure during mechanical extension remains unknown. Moreover, little is described about the effect of the mechanical stress on SC barrier function. In this study, we have examined the SC structure changes, at the molecular level, during uniaxial tensile experiments. This was performed on isolated SC samples using Raman spectroscopy. We could identify the strain status of the analyzed samples by using combination of Raman spectra and Partial Least Squares processing. In addition, this approach provided information about lipids and proteins behavior during the sample extension. The structure of the intercellular lipids bilayer became less organized up to ~9% deformation. For higher strains, a plateau corresponding to the minimum organization is observed till the complete failure of the sample. In the same time, protein structures including desmosomes, were characterized by monotonic secondary structure modifications for deformations up to ~9% followed by a plateau. These observations are relevantly demonstrating the effect of extension on the skin barrier state. Such an approach could be objectively used for clinical applications to evaluate skin discomfort degree and skin elastic behavior. This could therefore help with proof of efficacy for cosmetic and dermatologic products. Copyright © 2013 John Wiley & Sons, Ltd.