SYNTHESIS AND APPLICATION OF CROWN ETHERS

Mono- and bis-benzo-15-crown-5-ether derivatives have been synthesized and determined their potentiometric K+ selectivity factors. Of bis-crown ether urethanes highly selective Iigands were found some of which was used as active ingredient in potassium selective membrane electrode. Sugar based crown ethers, aza-crowns and cryptands were also prepared and applied as chiral catalyst in enantioselective reactions

FOULING AS INDICATOR OF AQUACULTURE INFLUENCE ON ENVIRONMENT

Ekološkim osvješćivanjem cjelokupne zajednice i širenjem akvakulturne aktivnosti na Jadranu sve se češće postavlja pitanje utjecaja akvakulture na okoliš. Kao jedan od temeljnih ciljeva u priobalnoj akvakulturi ističe se provođenje ekološke zaštite prirodnog okoliša. Proces obrastanja mreža koje se rabe za izradu kaveza pojavljuje se u određenom stupnju na svim lokacijama gdje se provodi uzgoj ribe. Periodičnim ispitivanjem obraštajnih organizama može se, uz već prije ustaljeni monitoring (kemizma sedimenta, kemizma vode, bentosne biote i fitoplanktona), pratiti utjecaj postojeće akvakulturne aktivnosti na okoliš. Kvalitativni i kvantitativni sastav obraštajnih organizama može upozoriti na određene promjene u okolišu. Također, postoje vrste koje svojom prisutnošću upozoravaju na promjene, tj. mogu se iskoristiti kao indikatori ekoloških promjena.By ecological awarening of the whole community and by the broadening of the aquacultural activity on the Adriatic, the influence of the aquaculture on the environment is more questionable. The opholding of the ecological protection of the natural environment is pointed out as one of the basic goals in the by–coastal aquaculture. The processes of the net fouling, which are used for the construction of the cages, is present to a certain degree at all locations of the fish breeding. By periodical investigation of the fouling organisms it is possible, with the earlier set monitoring (chemisms of the sediments, chemisms of the water, benthic biotes and phytoplankton) to follow the influence of the existing aquacultural activity on the environment. Qualitative and quantitative constitution of the fouling organisms can indicate certain changes in the environment. There are also species that can indicate changes by their presence, i. e. they can be used as indicators of the ecological changes

FOULING AS INDICATOR OF AQUACULTURE INFLUENCE ON ENVIRONMENT

Ekološkim osvješćivanjem cjelokupne zajednice i širenjem akvakulturne aktivnosti na Jadranu sve se češće postavlja pitanje utjecaja akvakulture na okoliš. Kao jedan od temeljnih ciljeva u priobalnoj akvakulturi ističe se provođenje ekološke zaštite prirodnog okoliša. Proces obrastanja mreža koje se rabe za izradu kaveza pojavljuje se u određenom stupnju na svim lokacijama gdje se provodi uzgoj ribe. Periodičnim ispitivanjem obraštajnih organizama može se, uz već prije ustaljeni monitoring (kemizma sedimenta, kemizma vode, bentosne biote i fitoplanktona), pratiti utjecaj postojeće akvakulturne aktivnosti na okoliš. Kvalitativni i kvantitativni sastav obraštajnih organizama može upozoriti na određene promjene u okolišu. Također, postoje vrste koje svojom prisutnošću upozoravaju na promjene, tj. mogu se iskoristiti kao indikatori ekoloških promjena.By ecological awarening of the whole community and by the broadening of the aquacultural activity on the Adriatic, the influence of the aquaculture on the environment is more questionable. The opholding of the ecological protection of the natural environment is pointed out as one of the basic goals in the by–coastal aquaculture. The processes of the net fouling, which are used for the construction of the cages, is present to a certain degree at all locations of the fish breeding. By periodical investigation of the fouling organisms it is possible, with the earlier set monitoring (chemisms of the sediments, chemisms of the water, benthic biotes and phytoplankton) to follow the influence of the existing aquacultural activity on the environment. Qualitative and quantitative constitution of the fouling organisms can indicate certain changes in the environment. There are also species that can indicate changes by their presence, i. e. they can be used as indicators of the ecological changes

The optical microscopy with virtual image breaks a record: 50-nm resolution imaging is demonstrated

We demonstrate a new 'microsphere nanoscope' that uses ordinary SiO2 microspheres as superlenses to create a virtual image of the object in near field. The magnified virtual image greatly overcomes the diffraction limit. We are able to resolve clearly 50-nm objects under a standard white light source in both transmission and reflection modes. The resolution achieved for white light opens a new opportunity to image viruses, DNA and molecules in real time

Network-based dissolution

We introduce a novel graph-theoretic dissolution model which applies to a number of redistribution scenarios such as gerrymandering or work economization. The central aspect of our model is to delete some vertices and redistribute their "load" to neighboring vertices in a completely balanced way. We investigate how the underlying graph structure, the pre-knowledge about which vertices to delete, and the relation between old and new "vertex load" influence the computational complexity of the underlying easy-to-describe graph problems, thereby identifying both tractable and intractable cases

Visualizing Escherichia coli Sub-Cellular Structure Using Sparse Deconvolution Spatial Light Interference Tomography

Studying the 3D sub-cellular structure of living cells is essential to our understanding of biological function. However, tomographic imaging of live cells is challenging mainly because they are transparent, i.e., weakly scattering structures. Therefore, this type of imaging has been implemented largely using fluorescence techniques. While confocal fluorescence imaging is a common approach to achieve sectioning, it requires fluorescence probes that are often harmful to the living specimen. On the other hand, by using the intrinsic contrast of the structures it is possible to study living cells in a non-invasive manner. One method that provides high-resolution quantitative information about nanoscale structures is a broadband interferometric technique known as Spatial Light Interference Microscopy (SLIM). In addition to rendering quantitative phase information, when combined with a high numerical aperture objective, SLIM also provides excellent depth sectioning capabilities. However, like in all linear optical systems, SLIM's resolution is limited by diffraction. Here we present a novel 3D field deconvolution algorithm that exploits the sparsity of phase images and renders images with resolution beyond the diffraction limit. We employ this label-free method, called deconvolution Spatial Light Interference Tomography (dSLIT), to visualize coiled sub-cellular structures in E. coli cells which are most likely the cytoskeletal MreB protein and the division site regulating MinCDE proteins. Previously these structures have only been observed using specialized strains and plasmids and fluorescence techniques. Our results indicate that dSLIT can be employed to study such structures in a practical and non-invasive manner

X-ray resonant photoexcitation: line widths and energies of K{\alpha} transitions in highly charged Fe ions

Photoabsorption by and fluorescence of the K{\alpha} transitions in highly charged iron ions are essential mechanisms for X-ray radiation transfer in astrophysical environments. We study photoabsorption due to the main K{\alpha} transitions in highly charged iron ions from heliumlike to fluorinelike (Fe 24+...17+) using monochromatic X-rays around 6.6 keV at the PETRA III synchrotron photon source. Natural linewidths were determined with hitherto unattained accuracy. The observed transitions are of particular interest for the understanding of photoexcited plasmas found in X-ray binaries and active galactic nuclei.Comment: Revised versio

Capping of the N-terminus of PSD-95 by calmodulin triggers its postsynaptic release

Postsynaptic density protein-95 (PSD-95) is a central element of the postsynaptic architecture of glutamatergic synapses. PSD-95 mediates postsynaptic localization of AMPA receptors and NMDA receptors and plays an important role in synaptic plasticity. PSD-95 is released from postsynaptic membranes in response to Ca2+ influx via NMDA receptors. Here, we show that Ca2+/calmodulin (CaM) binds at the N-terminus of PSD-95. Our NMR structure reveals that both lobes of CaM collapse onto a helical structure of PSD-95 formed at its N-terminus (residues 1-16). This N-terminal capping of PSD-95 by CaM blocks palmitoylation of C3 and C5, which is required for postsynaptic PSD-95 targeting and the binding of CDKL5, a kinase important for synapse stability. CaM forms extensive hydrophobic contacts with Y12 of PSD-95. The PSD-95 mutant Y12E strongly impairs binding to CaM and Ca 2+-induced release of PSD-95 from the postsynaptic membrane in dendritic spines. Our data indicate that CaM binding to PSD-95 serves to block palmitoylation of PSD-95, which in turn promotes Ca2+-induced dissociation of PSD-95 from the postsynaptic membrane. Synopsis Ca2+ influx promotes Ca2+/calmodulin binding to the N-terminus of PSD-95, which blocks PSD-95 palmitoylation leading to reduced retention of PSD-95 at synapses. This effect will likely decrease postsynaptic glutamate receptor content and thereby synaptic strength. Ca2+/calmodulin forms a collapsed structure around the N-terminal helix of PSD-95 that sequesters the palmitoylation sites (Cys3 and Cys5) and a key tyrosine (Tyr12). Binding of Ca2+/calmodulin to the N-terminus of PSD-95 decreases its palmitoylation to release PSD-95 from postsynaptic sites Binding of Ca 2+/calmodulin also displaces the serine/threonine kinase CDKL5 from PSD-95, which otherwise helps augment synaptic strength A point mutation of PSD-95 that prevents Ca2+/calmodulin binding turns the Ca 2+-induced reduction in PSD-95 at synapses into an increase, uncovering the existence of a second mechanism that augments postsynaptic PSD-95 enrichment upon Ca2+ influx. Ca2+ influx promotes Ca 2+/calmodulin binding to the N-terminus of PSD-95, which blocks PSD-95 palmitoylation leading to reduced retention of PSD-95 at synapses

Phase diagrams in nonlocal PNJL models constrained by Lattice QCD results

Based on lattice QCD-adjusted SU(2) nonlocal Polyakov--Nambu--Jona-Lasinio (PNJL) models, we investigate how the location of the critical endpoint in the QCD phase diagram depends on the strenght of the vector meson coupling, as well as the Polyakov-loop (PL) potential and the form factors of the covariant model. The latter are constrained by lattice QCD data for the quark propagator. The strength of the vector coupling is adjusted such as to reproduce the slope of the pseudocritical temperature for the chiral phase transition at low chemical potential extracted recently from lattice QCD simulations. Our study supports the existence of a critical endpoint in the QCD phase diagram albeit the constraint for the vector coupling shifts its location to lower temperatures and higher baryochemical potentials than in the case without it.Comment: 23 pages, 10 figures. Version accepted in Phys. Part. Nucl. Lett. (to appear), references adde

Monte Carlo Simulations indicate that Chromati: Nanostructure is accessible by Light Microscopy

A long controversy exists about the structure of chromatin. Theoretically, this structure could be resolved by scattering experiments if one determines the scattering function - or equivalently the pair distribution function - of the nucleosomes. Unfortunately, scattering experiments with live cells are very difficult and limited to only a couple of nucleosomes