Influence of Molecular Dipole Orientations on Long-Range Exponential Interaction Forces at Hydrophobic Contacts in Aqueous Solutions

Strong and particularly long ranged (>100 nm) interaction forces between apposing hydrophobic lipid monolayers are now well understood in terms of a partial turnover of mobile lipid patches, giving rise to a correlated long-range electrostatic attraction. Here we describe similarly strong long-ranged attractive forces between self-assembled monolayers of carboranethiols, with dipole moments aligned either parallel or perpendicular to the surface, and hydrophobic lipid monolayers deposited on mica. We compare the interaction forces measured at very different length scales using atomic force microscope and surface forces apparatus measurements. Both systems gave a long-ranged exponential attraction with a decay length of 2.0 +/- 0.2 nm for dipole alignments perpendicular to the surface. The effect of dipole alignment parallel to the surface is larger than for perpendicular dipoles, likely due to greater lateral correlation of in-plane surface dipoles. The magnitudes and range of the measured interaction forces also depend on the surface area of the probe used: At extended surfaces, dipole alignment parallel to the surface leads to a stronger attraction due to electrostatic correlations of freely rotating surface dipoles and charge patches on the apposing surfaces. In contrast, perpendicular dipoles at extended surfaces, where molecular rotation cannot lead to large dipole correlations, do not depend on the scale of the probe used. Our results may be important to a range of scale-dependent interaction phenomena related to solvent/water structuring on dipolar and hydrophobic surfaces at interfaces

Optimalization of Freight Railway Transport

1 Introduction 2 Optimization models used in the rail transport 2.1 Distributional models 2.1.1 Transportation Problem 2.1.2 General Transportation Problem 2.1.3 Travelling Salesman Problem 2.2 Introduction to the Blocking Problem 2.2.1 Describtion of the Blocking Problem 2.2.2 Network Design Model 2.2.3 Objective Function 2.2.4 Column Generation 2.2.5 Branch and Price Algorithm 2.2.6 Evaluation of Model 3 Conclusion 4 List of the Literatur

Nano-nosičový systém pro neutronovou záchytovou terapii - nová řešení BNCT

Presenting of results dealing with carriers for boron drug delivery for treatment of cancer. We discussed future development and biological tests necessary for application

The Depandance of Development of Shares on Technical Analysis Indicators

The aim of the Thesis is to determine the influence of technical analysis to the profitability of shares by O2 Telefónica, Komerční banka and ČEZ whan applied to a predeterminated trading model and judge the validity of Efective Markets Theory. It will be also followed up the influence of trading signals of technical indicators on the shape and characteristics of conditional distribution set by those signals. The Crystal Ball was used as the main software tool. This software dispose of all tools necesarry for the analysis. There is also desribed the theoretical background of areas like shares, technical analysis, random quantity distribution, generating of random numbers and other related areas in the Thesis, so the reader who does not understand the problemacy could understand the best.Cílem diplomové práce je určit vliv technické analýzy na výši zhodnocení akciových titulů společností O2 Telefónica, Komerční banka a ČEZ při aplikaci na předem určený obchodní model a posoudit platnost teorie efektivních trhů u týchž akciových titulů. Rovněž bude sledován vliv obchodních signálů technických indikátorů na tvar a charakteristiky podmíněných rozdělení jimi danými. Jako hlavní softwarový nástroj byl použit doplněk Microsoft Excellu Crystal Ball. Tento software disponuje všemi potřebnými nástroji pro výše zmíněnou analýzu. V práci jsou rovněž představena teoretická východiska z oblastí akcií, technické analýzy, rozdělení náhodných veličin, generování náhodných čísel a jim blízkých oblastí tak, aby jí co nejlépe porozuměl i čtenář neznalý problematiky

Reversible capture of small molecules on bimetallaborane clusters: Synthesis, structural characterization, and photophysical aspects

Metallaborane compounds containing two adjacent metal atoms, [(PMe2Ph)4MM′B10H10] (where MM′ = Pt2, 1; PtPd, 7; Pd2, 8), have been synthesized, and their propensity to sequester O2, CO, and SO2 and to then release them under pulsed and continuous irradiation are described. Only [(PMe2Ph)4Pt2B10H10], 1, undergoes reversible binding of O2 to form [(PMe2Ph)4(O2)Pt2B10H10] 3, but solutions of 1, 7, and 8 all quantitatively take up CO across their metal–metal vectors to form [(PMe2Ph)4(CO)Pt2B10H10] 4, [(PMe2Ph)4(CO)PtPdB10H10] 10, and [(PMe2Ph)4(CO)Pd2B10H10] 11, respectively. Crystallographically determined interatomic M–M distances and infrared CO stretching frequencies show that the CO molecule is bound progressively more weakly in the sequence {PtPt} > {PtPd} > {PdPd}. Similarly, SO2 forms [(PMe2Ph)4(SO2)Pt2B10H10] 5, [(PMe2Ph)4(SO2)PtPdB10H10] 12, and [(PMe2Ph)4(SO2)Pd2B10H10] 13 with progressively weaker binding of the SO2 molecule. The uptake and release of gas molecules are accompanied by changes in their absorption spectra. Nanosecond transient absorption spectroscopy clearly shows that the O2 and CO molecules are liberated from the bimetallic binding site with high quantum yields of about 0.6. For 3, in addition to dioxygen release in the triplet ground state, singlet oxygen O2(1Δg) was also detected with a quantum yield 1 ns). All these compounds may have potential to serve as light-triggered local and instantaneous sources of the studied gases.This work was supported by the Czech Science Foundation (Nos. P207/11/1577, P208/10/1678), the Grant Agency of the Academy of Sciences of the Czech Republic (KAN400480701), and the Spanish Ministry of Science Innovation (projects CSD2009-50, CTQ2009-10132, and a sabbatical leave, SAB2009-0191, to J.B.).Peer reviewe

Decaborane thiols as building bBlocks for self-assembled monolayers on metal surfaces

Three nido-decaborane thiol cluster compounds, [1-(HS)-nido-B10H13] 1, [2-(HS)-nido-B10H13] 2, and [1,2-(HS)2-nido-B10H12] 3 have been characterized using NMR spectroscopy, single-crystal X-ray diffraction analysis, and quantum-chemical calculations. In the solid state, 1, 2, and 3 feature weak intermolecular hydrogen bonding between the sulfur atom and the relatively positive bridging hydrogen atoms on the open face of an adjacent cluster. Density functional theory (DFT) calculations show that the value of the interaction energy is approximately proportional to the number of hydrogen atoms involved in the interaction and that these values are consistent with a related bridging-hydrogen atom interaction calculated for a B18H22·C6H6 solvate. Self-assembled monolayers (SAMs) of 1, 2, and 3 on gold and silver surfaces have been prepared and characterized using X-ray photoelectron spectroscopy. The variations in the measured sulfur binding energies, as thiolates on the surface, correlate with the (CC2) calculated atomic charge for the relevant boron vertices and for the associated sulfur substituents for the parent B10H13(SH) compounds. The calculated charges also correlate with the measured and DFT-calculated thiol 1H chemical shifts. Wetting-angle measurements indicate that the hydrophilic open face of the cluster is directed upward from the substrate surface, allowing the bridging hydrogen atoms to exhibit a similar reactivity to that of the bulk compound. Thus, [PtMe2(PMe2Ph)2] reacts with the exposed and acidic B–H–B bridging hydrogen atoms of a SAM of 1 on a gold substrate, affording the addition of the metal moiety to the cluster. The XPS-derived stoichiometry is very similar to that for a SAM produced directly from the adsorption of [1-(HS)-7,7-(PMe2Ph)2-nido-7-PtB10H11] 4. The use of reactive boron hydride SAMs as templates on which further chemistry may be carried out is unprecedented, and the principle may be extended to other binary boron hydride clusters.This work was supported by the Grant Agency of the Czech Republic (Grants P207/11/1577 and P205/10/0348) and by the Grant Agency of the Academy of Sciences of the Czech Republic (Grants KAN400480701, KAN100400702, IAA 400320901, M200320904). J.B. wishes to thank the Spanish Ministry of Science Innovation for sabbatical funding (SAB2009-0191).Peer reviewe

10-Vertex closo-carborane: a unique ligand platform for porous coordination polymers

1,10-Dicarboxy-1,10-dicarba-closo-decaborane, a classical dicarboxylate spacer ligand type similar to the prototypical terephthalic acid, proved to be different not only from the latter, but also from its closest relative compound, 1,12-dicarboxy-closo-1,12-dicarbadecaborane, with regard to the topology of its derived PCPs. Highly porous and robust compounds of zinc (rob net) and cobalt (‘quasi’ pcu) as well as a topologically unexpected copper compound (lvt) define the individuality of the 10-vertex carborane cage as a new fundamental spacer type in PCP chemistry. A combination of a lower steric demand compared to the 12-vertex analogue, a preferred orientation angle of 45° between the carboxylate planes and a moderately low rotation barrier are held responsible for the uniqueness of the 10-vertex analogue.crosscheck: This document is CrossCheck deposited related_data: Supplementary Information related_data: Crystal Structure Data copyright_licence: The Royal Society of Chemistry has an exclusive publication licence for this journal history: Received 20 December 2015; Accepted 15 February 2016; Accepted Manuscript published 16 February 2016; Advance Article published 1 March 2016; Version of Record published 14 March 2016status: publishe

Surface Dipole Control of Liquid Crystal Alignment.

Detailed understanding and control of the intermolecular forces that govern molecular assembly are necessary to engineer structure and function at the nanoscale. Liquid crystal (LC) assembly is exceptionally sensitive to surface properties, capable of transducing nanoscale intermolecular interactions into a macroscopic optical readout. Self-assembled monolayers (SAMs) modify surface interactions and are known to influence LC alignment. Here, we exploit the different dipole magnitudes and orientations of carboranethiol and -dithiol positional isomers to deconvolve the influence of SAM-LC dipolar coupling from variations in molecular geometry, tilt, and order. Director orientations and anchoring energies are measured for LC cells employing various carboranethiol and -dithiol isomer alignment layers. The normal component of the molecular dipole in the SAM, toward or away from the underlying substrate, was found to determine the in-plane LC director orientation relative to the anisotropy axis of the surface. By using LC alignment as a probe of interaction strength, we elucidate the role of dipolar coupling of molecular monolayers to their environment in determining molecular orientations. We apply this understanding to advance the engineering of molecular interactions at the nanoscale