Photoinduced Doughnut-Shaped Nanostructures

We show that an incoherent unpolarized single-beam illumination is able to photoinduce nano-doughnuts on the surface of azopolymer thin films. We demonstrate that individual doughnut-shaped nano-objects as well as clusters of several adjacent nano-doughnuts can be formed and tailored with wide range of typical sizes, thus providing a rich field for applications in nanophotonics and photochemistry.Comment: 13 pages, 3 figures, first version to chem. phys. lett. 201

A macroscopic quantum state analysed particle by particle

Explaining how microscopic entities collectively produce macroscopic phenomena is a fundamental goal of many-body physics. Theory predicts that large-scale entanglement is responsible for exotic macroscopic phenomena, but observation of entangled particles in naturally occurring systems is extremely challenging. Synthetic quantum systems made of atoms in optical lattices have been con- structed with the goal of observing macroscopic quantum phenomena with single-atom resolution. Serious challenges remain in producing and detecting long-range quantum correlations in these systems, however. Here we exploit the strengths of photonic technology, including high coherence and efficient single-particle detection, to study the predicted large-scale entanglement underlying the macroscopic quantum phenomenon of polarization squeezing. We generate a polarization-squeezed beam, extract photon pairs at random, and make a tomographic reconstruction of their joint quantum state. We present experimental evidence showing that all photons arriving within the squeezing coherence time are entangled, that entanglement monogamy dilutes entanglement with increasing photon density and that, counterintuitively, increased squeezing can reduce bipartite entanglement. The results provide direct evidence for entanglement of macroscopic numbers of particles and introduce micro-analysis to the study of macroscopic quantum phenomena

Dependence of nonlinear refractive index of ZnSe on Be and Mg content

The values of the nonlinear refractive index n(2) and the two-photon absorption coefficient beta of ternary and quaternary ZnSe-based mixed crystals were extracted from the standard backward degenerate four wave mixing (DFWM) and nonlinear transmission measurements at 532 nm, respectively. Studied crystals were grown by the modified high-pressure Bridgman method. We found that the value of the nonlinear refractive index n(2) for Zn(0.79)Be(0.21)Se is higher than that for Zn(0.80)Mg(0.20)Se. However, the opposite behaviour was found in the case of two-photon absorption coefficient beta for these compounds. We also found that the values of the nonlinear refractive index n(2) and the two-photon absorption coefficient beta for Zn(0.83)Be(0.04)Mg(0.13)Se are about five times lower and three times higher than that for Zn(0.80)Mg(0.13)Se, respectively. In the case of ternary ZnSe-based crystals we noticed that the value of the nonlinear refractive index n2 decreases with increasing Mg or Be content. However, the value of the two-photon absorption coefficient beta increases with increasing Mg or Be content

Biomaterials with potential use in bone tissue regeneration-collagen/chitosan/silk fibroin scaffolds cross-linked by EDC/NHS

Blending of different biopolymers, e.g., collagen, chitosan, silk fibroin and cross-linking modifications of these mixtures can lead to new materials with improved physico-chemical properties, compared to single-component scaffolds. Three-dimensional scaffolds based on threecomponent mixtures of silk fibroin, collagen and chitosan, chemically cross-linked, were prepared and their physico-chemical and biological properties were evaluated. A mixture of EDC (N-(3- dimethylaminopropyl)-N’-ethylcarbodiimide hydrochloride) and NHS (N-hydroxysuccinimide) was used as a cross-linking agent. FTIR was used to observe the position of the peaks characteristic for collagen, chitosan and silk fibroin. The following properties depending on the scaffold structure were studied: swelling behavior, liquid uptake, moisture content, porosity, density, and mechanical parameters. Scanning Electron Microscopy imaging was performed. Additionally, the biological properties of these materials were assessed, by metabolic activity assay. The results showed that the three-component mixtures, cross-linked by EDC/NHS and prepared by lyophilization method, presented porous structures. They were characterized by a high swelling degree. The composition of scaffolds has an influence on mechanical properties. All of the studied materials were cytocompatible with MG-63 osteoblast-like cells.This research was founded by National Science Centre, grant 2018/31/N/ST8/01391 and by Polish National Agency for Academic Exchange, Iwanowska project PPN/IWA/2018/1/00064/U/00001

Near-Field Optical control of Doughnut-Shaped Nanostructures

The application of a local near-field optical excitation can be used to control step-by-step the reshape of individual doughnut-shaped azopolymer nano-objects by varying the time of illumination demonstrating its promising performance as a functional nano-object. The possibility to provide both photoinduced reshaping opens a way to the fundamental study of size-dependent scaling laws of optical properties, photoinduced reshaping efficiency and nanoreactor or nanoresonator behavior at nanometer scale. As an example the nano-object is used to self-assembly polystyrene nanospheres in a supraball.Comment: 15 pages, 6 figure

Smart nanogels at the air/water interface: structural studies by neutron reflectivity

STFC for provision of consumables and subsistence and access to the ILL facility through the STFC managed UK contribution to the facility (EXP: 9-13-530, 9-11-1721 and 9-11-17446). The European Commission (FP7 Marie Curie Actions, NANOLEM, PIEF-GA-2013-627146 to KZ) and the Chinese Scholarship Council (studentship to HS) are gratefully acknowledged for financial support