Phase Behavior of Melts of Diblock-Copolymers with One Charged Block

In this work we investigated the phase behavior of melts of block-copolymers with one charged block by means of dissipative particle dynamics with explicit electrostatic interactions. We assumed that all the Flory-Huggins \c{hi} parameters were equal to 0 and showed that the charge correlation attraction solely can cause microphase separation with long-range order; a phase diagram was constructed by varying the volume fraction of the uncharged block and the electrostatic interaction parameter {\lambda}. The obtained phase diagram was compared to the phase diagram of corresponding neutral diblock-copolymers. Surprisingly, the differences between these phase diagrams are rather subtle; the same phases are observed, and the positions of the ODT points are similar if the {\lambda}-parameter is considered as an "effective" \c{hi}-parameter. Next, we studied the position of the ODT for lamellar structure depending on the chain length N. It turned out that while for the uncharged diblock-copolymer the product \c{hi}crN was almost independent of N, for the diblock-copolymers with one charged block we observed a significant increase in {\lambda}crN upon increasing N. It can be attributed to the fact that the counterion entropy prevents the formation of ordered structures. This was supported by studying the ODT in diblock-copolymers with charged blocks and counterions cross-linked to the charged monomer units. The ODT for such systems was observed at significantly lower values of {\lambda} with the difference being more pronounced at longer chain lengths N. The diffusion of counterions in the obtained ordered structures was studied and compared to the case of a system with the same number of charged groups but homogeneous structure; the diffusion coefficient in a direction in the lamellar plane was found to be higher than in any direction in homogeneous structure

Green function for hyperbolic media

We revisit the problem of the electromagnetic Green function for homogeneous hyperbolic media, where longitudinal and transverse components of the dielectric permittivity tensor have different signs. We analyze the dipole emission patterns for both dipole orientations with respect to the symmetry axis and for different signs of dielectric constants, and show that the emission pattern is highly anisotropic and has a characteristic cross-like shape: the waves are propagating within a certain cone and are evanescent outside this cone. We demonstrate the coexistence of the cone-like pattern due to emission of the extraordinary TM-polarized waves and elliptical pattern due to emission of ordinary TE-polarized waves. We find a singular complex term in the Green function, proportional to the $\delta-$function and governing the photonic density of states and Purcell effect in hyperbolic media.Comment: 10 pages, 7 figure

The Sediments Flow of the Main Baikal Rivers and Its Sensitivity to the Environmental Change (East Siberia, Russia)

The results of the analysis of water and sediments flows’ changes of main inflowing Baikal rivers over the observation period are presented. Long-term observation record of sediments flow is divided into two periods differ with average values and a scale fluctuations of annual averages values. During the first period dynamics of sediments flow of rivers is determined by hydro-climatic factors, i.e. fluctuations of sediments flow, in general, are synchronous to fluctuations of water flow. During the second period (from the second half of 1970s) there is the downward trend of sediments flow’s change (decrease by 48 – 81%) against the background of increased water content of rivers. This trend is caused by both anthropogenic influence in basins of rivers under review and natural processes, connected to global and regional changes of climatic characteristics. In general, natural processes of sediments flow’s changes in the different areas of Baikal basin are adjusted by anthropogenic factors to a greater or lesser extent. The present article can be used as information and analytical material for the further research and forecast of sediments flow’s changes in Baikal basin as well as in other rift-valley lakes of the world. Keywords: Lake Baikal, water and sediments flow, trends, antropogenic factor, climate chang

Adaptive microgels in complexes and at interfaces

Microgels are macromolecular networks swollen by the solvent they are dissolved in. They are unique systems that are distinctly different from common colloids, such as, e.g., rigid nanoparticles, flexible macromolecules, micelles or vesicles. When swollen, they are soft and have a fuzzy surface with dangling chains and the presence of cross-links provides structural integrity - in contrast to linear and (hyper-) branched polymers. Obviously, the cross-linker content will allow controlling whether microgels behave more ”colloidal” or ”macromolecular”. Finally, microgels reveal interfacial activity without being amphiphilic. The combination of being soft and porous while still having a stable structure through the cross-linked network allows for the possibility to introduce chemical functionality at different positions. The architectural diversity and compartmentalization of reactive groups enable thus short-range coexistence of otherwise unstable combinations of chemical reactivity. The capability of microgels to adjust both their shape and volume in response to external stimuli provides the opportunity to reversibly tune their physico-chemical properties. From a physics point of view, microgels are particularly intriguing and challenging, since their intra-particle properties are intimately linked to their inter-particle behavior. We will discuss the interaction of microgels of different architecture as, e.g., core-shell, hollow and multi-shell hollow microgels with polyelectrolytes and proteins. The formation of polyelectrolyte complexes was studied and especially amphoteric microgels enable controlled uptake and release. The solution structure was determined by means of neutron and light scattering as well as by (super-resolved) fluorescence microscopy. Furthermore, we investigate the influence of the structure of microgels on their behavior at interfaces. Here, the structure was probed by means of scanning force and electron microscopy. Compression isotherms of the microgel-laden oil-water interfaces reveal spreading of the microgels at the interface and counter-intuitive influences of charged groups and cross-link density on the compression modulus. The experimental results are fully supported by computer simulations and illustrate the special behavior of soft microgels at interfaces. Plamper, F. A.; Richtering, W. Functional Microgels and Microgel Systems. Accounts of Chemical Research 2017, 50, 131–140. Yaroslavov, A.; Panova, I.; Sybachin, A.; Spiridonov, V.; Zezin, A.; Mergel, O.; Gelissen, A.; Tiwari, R.; Plamper, F.; Richtering, W.; et al. Payload Release by Liposome Burst: Thermal Collapse of Microgels Induces Satellite Destruction. Nanomedicine: nanotechnology, biology, and medicine 2017, DOI:10.1016/j.nano.2017.02.001 Gelissen, A. P. H.; Oppermann, A.; Caumanns, T.; Hebbeker, P.; Turnhoff, S. K.; Tiwari, R.; Eisold, S.; Simon, U.; Lu, Y.; Mayer, J.; et al. 3D Structures of Responsive Nanocompartmentalized Microgels. Nano Lett. 2016, 16, 7295–7301. Schmid, A. J.; Dubbert, J.; Rudov, A. A.; Pedersen, J. S.; Lindner, P.; Karg, M.; Potemkin, I. I.; Richtering, W. Multi-Shell Hollow Nanogels with Responsive Shell Permeability. Scientific Reports 2016, 6, 22736. Sigolaeva, L. V.; Mergel, O.; Evtushenko, E. G.; Gladyr, S. Y.; Gelissen, A. P. H.; Pergushov, D. V.; Kurochkin, I. N.; Plamper, F. A.; Richtering, W. Engineering Systems with Spatially Separated Enzymes via Dual-Stimuli- Sensitive Properties of Microgels. Langmuir 2015, 31, 13029–13039. Geisel, K.; Isa, L.; Richtering, W. The Compressibility of pH-Sensitive Microgels at the Oil-Water Interface: Higher Charge Leads to Less Repulsion. Angew. Chem. Int. Ed. Engl. 2014, 53, 4905–4909

Bryophytes of Mordovia State Nature Reserve (European Russia)

The present study compiles the results of bryophyte species inventories made at the Mordovia State Nature Reserve from 2014 till 2016. The reserve is located near southern limit of deciduous-coniferous forest subzone. In total 96% of the reserve is covered by forests, where about half are pine forests. The annotated bryophyte checklist includes 142 moss species and 23 liverwort species. The data on collecting site characteristics, habitats, substrates, bryophyte species frequency, and sporophyte presence are provided. Presented treatment is a key contribution to the bryophyte flora of Mordovia and important for the knowledge on bryophyte distribution of this forested area within strongly anthropogenically disturbed European Russian landscape.

Regulation of Zn2+ and aggregation affects Aβ1-42- induced changes in cell culture viability.

In the story of the pathogenesis of Alzheimer’s Disease, Amyloid-Beta (Aβ) is believed to play a key role. However, evidence suggests that metal ions, in particular Zn2+, may have strong modulatory, or even causative effects on the development of the disease. This study aimed to shed more light on the relationship between Aβ and Zn2+, especially with regards to their effects on cell viability. First, a protocol for the production of recombinant Aβ1-42 was followed to produce and purify the peptide. The next step was to establish a consistent cellular insult paradigm using Aβ1-42 in SH-SY5Y neuroblastoma cells, paying particular attention to aggregating the peptide – an important factor in Aβ toxicity. Subsequently this study aimed to investigate the effect of addition of exogenous Zn2+ on cell viability and its interaction with Aβ1-42. The production and purification protocol was successful in yielding quantities of pure Aβ. However, this protocol may require further optimisation. It was noted that while many research groups continue to use the MTT assay to measure cell viability, the large variability of the assay and the reported biochemical interaction with the Aβ peptide make it inappropriate. As such, this study used the resazurin assay. This research was unable to establish a consistent cellular insult paradigm in either SH-SY5Y neuroblastoma cells or cultured rat hippocampal or cortical cells (p>0.05; n=3). This was despite an ageing protocol able to produce oligomers and protofibrils of Aβ, species previously shown to have toxic effects on cell cultures. In fact, protofibril-containing samples of the peptide at 20 and 40 µM increased cell viability of neuroblastoma cultures above the control (by 0.22±0.039 and 0.36±0.041 respectively; p0.1;n=4). Finally, addition of exogenous Zn2+ in some cases complimented Aβ-induced increases in cell viability, although this effect was inconsistent. This research highlighted some of the difficulties in examining Aβ in cell culture. In particular, it seemed important to not only identify the aggregation state of Aβ peptides, but also isolate and test specific species. This research suggests, however, that Zn2+ does modulate the effects of Aβ on cell viability and this relationship requires further investigation

CASH AT E-COMMERCE: METHOD FOR DISBURSING CASH TO A CARDHOLDER USING AN E-COMMERCE PLATFORM

The present disclosure relates to a method for disbursing cash to a cardholder using an e-commerce platform. The present disclosure discloses a method of provisioning a user to initiate a transaction by ordering a product or service using an eCommerce application or a website. The user can also request an additional cashback amount along with the ordered product/service during the transaction. After successful authentication of the request, the ordered product/service and the requested cashback amount (i.e., the cash) are delivered to the user