Origin of de-swelling and dynamics of dense ionic microgel suspensions

A direct consequence of the finite compressibility of a swollen microgel is that it can shrink and deform in response to an external perturbation. As a result, concentrated suspensions of these particles exhibit relaxation dynamics and rheological properties which can be very different with respect to those of a hard sphere suspension or an emulsion. We study the reduction in size of ionic microgels in response to increasing number of particles to show that particle shrinkage originates primarily from steric compression, and that the effect of ion-induced de-swelling of the polymer network is negligible. With increasing particle concentration, the single particle dynamics switch from those typical of a liquid to those of a super-cooled liquid and finally to those of a glass. However, the transitions occur at volume fractions much higher than those characterizing a hard sphere system. In the super-cooled state, the distribution of displacements is non-gaussian and the dependence of the structural relaxation time on volume fraction is describable by a Volger-Fulcher-Tammann function.     

Polymerization-induced phase separation as a one-step strategy to self-assemble alkanethiol-stabilized gold nanoparticles inside polystyrene domains dispersed in an epoxy matrix

The rational design of nanoparticle (NP)/polymer composites with advanced functional properties is based on controlling the distribution and self-assembly of NPs in the polymer matrix. In this study we report a new one-step strategy to produce the self-assembly of alkanethiol-stabilized Au NPs in one of the phases generated by polymerization-induced phase separation. The polymerization of a formulation composed of stoichiometric amounts of diglycidylether of bisphenol A (DGEBA) and m-xylylenediamine (mXDA), containing polystyrene (PS) and dodecanethiol-stabilized Au NPs as modifiers, produced the phase separation of PS and Au NPs into microdomains dispersed in the epoxy matrix. A subsequent phase separation and self-assembly of Au NPs took place inside the PS domains leading to an increase in their concentration in a region close to the interface as revealed by TEM images. SAXS spectra showed that NPs self-assembled as colloidal crystals with a body-centered cubic (bcc) structure. By an adequate selection of the amount of PS and the nature of the epoxy precursors, different morphologies of the final blend could be generated. This brings the possibility of controlling the dispersion and self-assembly of NPs in the final material.     

Integrated tunable liquid optical fiber

We present an integrated tunable liquid-core/liquid-cladding (L2) optical fiber, based on a novel three-dimensional hydrodynamic focusing scheme that enables the production of a tunable circular liquid core located in the center of the channel, regardless of the flow-rate ratio of the cladding and core liquids.     

Time evolution of non-lethal infectious diseases: a semi-continuous approach

A model describing the dynamics related to the spreading of non-lethal infectious diseases in a fixed-size population is proposed. The model consists of a non-linear delay-differential equation describing the time evolution of the increment in the number of infectious individuals and depends upon a limited number of parameters. Predictions are in good qualitative agreement with data on influenza, which is taken to be a representative type of non-lethal infectious disease.     

Re‐examination of the C6Li6 Structure: To Be,or not To Be Symmetric

The potential energy surface of C₆Li₆ was re‐examined and a new non‐symmetric global minimum was found. The new structure can be described as three C₂^2? fragments strongly aggregated through lithium bridges. At high temperatures, fluxionality is perceived instead of dissociation. At 600 and 900 K, the BOMD simulations show that the lithium mobility is high, indicating that the cluster behaves in a liquid‐like manner (BOMD=Born–Oppenheimer molecular dynamics).     

Observation of tunable optical filtering in photosensitive composite structures containing liquid crystals

We report on the investigation and characterization of an optically tunable filtering effect, observed in a waveguide grating made of alternated strips of photocurable polymer and a mixture of azo-dye-doped liquid crystal. The grating is sandwiched between two borosilicate glasses, one of which includes an ion-exchanged channel waveguide, which confines the optical signal to be filtered. Exposure to a low power visible light beam modifies the azo-dye molecular configuration, thus allowing the filtered wavelength to be tuned over a 6.6 nm range. Simulations of the filtering response are well described with our experimental findings.     

Assessment of calibration parameters for gamma-ray spectrometry systems

The Gamma-ray spectrometers are complex instruments and the quality of the data they provide depends strongly on their proper calibration. This paper describes the energy and efficacy calibration of two gamma-ray spectrometers in order to validate the method for measuring the activity of gamma-ray emitting radionuclides. The punctiform standard sources ⁶⁰Co, ¹³³Ba, ¹³⁷Cs and ²⁴¹Am were used in this study. Minimum Detectable Activity, Peak to Compton Ratio and the peak shape parameters were determinate. An inter-comparison of the results obtained with both systems was done. The results demonstrated that the activity values are comparable with low errors respecting with those for conventionally true activities.     

Combination of Heme Oxygenase-1 Inhibition and Sigma Receptor Modulation for Anticancer Activity

Cancer is a multifactorial disease that may be tackled by targeting different signaling pathways. Heme oxygenase-1 (HO-1) and sigma receptors (σRs) are both overexpressed in different human cancers, including prostate and brain, contributing to the cancer spreading. In the present study, we investigated whether HO-1 inhibitors and σR ligands, as well a combination of the two, may influence DU145 human prostate and U87MG human glioblastoma cancer cells proliferation. In addition, we synthesized, characterized, and tested a small series of novel hybrid compounds (HO-1/σRs) 1–4 containing the chemical features needed for HO-1 inhibition and σR modulation. Herein, we report for the first time that targeting simultaneously HO-1 and σR proteins may be a good strategy to achieve increased antiproliferative activity against DU145 and U87MG cells, with respect to the mono administration of the parent compounds. The obtained outcomes provide an initial proof of concept useful to further optimize the structure of HO-1/σRs hybrids to develop novel potential anticancer agents.